Sick of foreign countries getting rich from the money we spend???

YES I am sick and tired of the taxes and rising prices of petrol / diesel fuels and other essential commodities.

I pay all this money just to pay crappy things of all types to crappy people. The same people (government & co.) told us then to conserve on fuel, check the air in your tires, use cruise control, and drive slower. They told it to us day and night, on television, in newspapers, the radio, on billboards, in school, everywhere you went. Wind power, air power, sun power, waterpower, and even manure power, blah, blah, blah.

Did we learn anything from all this wonderful and informative tax-paid education? No. As soon as the crisis (which is a fake organized business to fuckup..........see dumpsters and recycling sites) was over, gas stabilized in the dollar range, staying that way until the last several years. The only ones who learned anything in all this were the Middle Eastern countries.

Now instead of just cutting us off, they slow the supply down and raise the price (and feed us more invasions of "migrants" wich are only resource consumers / stealers and land destroyers) If we do not do our part, then we should stop running to the politicians and complaining, because they will not be much help anyway.............(to be clear nothing if not worse)

In a European country or the USA, I might pay upto 50% tax, but fortunately i've decided to change winter warming technology from oil to this...............here today.

From my previsions and calculations the price to obtain same and higlhy more efficient warming in winter seasons and further cooling in more rising summer temperatures will be reduced to at least 1/4 if not better with this machinery........................a refrigerator........which coooooools...............and warms up....................let's see.....................

The MITSUBISHI PKA-RP100KAL + MITSUBISHI PUHZ-ZRP100VKA MR.SLIM POWER INVERTER AIR CONDITIONER R410A Wall Mounted System,Advanced inverter technology makes the Mr Slim Power Inverter the number one choice for improving comfort. They provide energy savings of up to 70% annually when compared to a previous non-inverter model.

Air conditioning is regarded as a significant user of energy in buildings across the EU. The Ecodesign Directive is focusing on this
area in a bid to reduce overall energy consumption, and to accelerate market transformation to more energy efficient products.
An air conditioner will vary performance over changing seasons which means calculating seasonal performance is important to ascertain
the true performance of an air conditioning system. Ecodesign Directive reflects this by setting minimum efficiency requirements and a
new method of measuring performance introduced across the EU and hence new energy ratings are achievable. The European Standard
BSEN14825:2012 sets the seasonal performance calculation for an air conditioning system under 12kW of which the energy efficiency
class for each product specification is shown.

The Mr Slim range offers Standard Inverter models, highly efficient Power Inverter
models and unique Zubadan models which provide optimum performance at
low ambient temperature conditions.
The full Mr Slim range has been completely redesigned to meet the new
Ecodesign Directive for Energy Related Products (ErP).
This enables the entire range to be one of the most efficient in the
industry with energy efficiency class up to A++.

PKA-RP Power Inverter Heat Pump.

FEATURES:

Flat panel, compact indoor unit design
Adjustable louvres for uniform air distribution
Internal pipe connection to wall mounted unit for easy and neat installation,

PKA-RP100KAL Indoor Unit
Capacity (kW):
Heating (Nominal) (Low - High)   11.20 (4.50 - 14.00)
Cooling (Nominal) (Low - High)   10.00 (4.90 - 11.40)
Heating (UK) (Low - High)   9.50 (3.85 - 11.90)
Cooling (UK) (Low - High)   9.20 (4.50 - 10.50)
SHF R410A (Nominal)   0.73
COP / EER (Nominal)   3.61 / 3.45
Energy Label Heating / Cooling   A / A
Width - mm   1170
Depth - mm   295
Height - mm   365
Weight - kg   21
Airflow (m3/min) - Lo-Mi-Hi   20-23-26
Noise (dBA) - Lo-Mi-Hi   41-45-49
Electrical Supply   Fed by Outdoor Unit
Phase   Single
Fuse Rating (BS88) - HRC (A)   6
Interconnecting Cable No. Cores   4

P Series Air Conditioner and Heat Pump
The Attraction of Being Untraditional
Mr. Slim P-Series is the ductless solution for demanding environments that require an efficient and reliable heating or cooling system. P-Series ductless systems are stylish, compact, and more attractive than traditional systems. Advanced technology also means your Mr. Slim ductless system will run more efficiently than a conventional unit, saving you from rising energy costs.

Designed for the Toughest Environment
No two buildings are alike. Each design, each floor plan, each room offers its own challenges for something as important as proper air conditioning and circulation. Mr. Slim systems are designed to adapt to your needs. Reliable, easy to install, and extremely quiet. Mr. Slim systems are powerful enough for the toughest situations, from offices and server rooms to equipment rooms. restaurants and retail locations.

PUHZ-ZRP100VKA POWER INVERTER R410A Outdoor Unit (The BEAST)

Electrical Supply   Fed by Mains to indoor unit
SystemPower Input (kW) - Heating (Nominal)   3.1
SystemPower Input (kW) - Cooling (Nominal)   2.9
SystemPower Input (kW) - Heating (UK)   2.76
SystemPower Input (kW) - Cooling (UK)   2.47
Starting Current (A)   5
SystemRunning Current (A) - Heating / Cooling   14.15 / 13.25.

Variable Compressor Speed Inverter Technology:MITSUBISHI ELECTRIC PUHZ-ZRP100VKA

At the heart of Mr. Slim P-Series ductless air conditioners and heat pumps lies Variable Compressor Speed Inverter (VCSI) technology Unlike conventional machines which only cycle between On and Off, VCSI systems detect changes in room temperature and readjust the compressor Speed to provide high-speed cooling or heating as needed. This means the space maintains a consistent, accurate temperature for the ultimate in comfort, all while using only the power that's needed. By adjusting the air conditioning capacity to run more efficiently, your energy costs are reduced.

VCSI technology saves energy in two ways:

VCSI system varies the compressor speed to match the additional load with the potential capacity. When the needs of a room expand - more people in a conference room or auditorium, or an increase in equipment in a server room-so do the needs to maintain consistent temperature levels. By allocating potential capacity to meet the changing demands, VCSI system uses only the energy needed in any given situation.

VCSI system operates efficiently at partial load conditions. Once the desired temperature of the room is reached, the compressor slows down to maintain a constant temperature. By slightly adjusting compressor speed rather than shutting off and on again, energy consumption is kept at a minimum. This is because VCSI system is operating at partial load for maximum efficiency, thus no more excess energy use wasted for running maximum capacity unnecessary on a fixed speed system.An object is to provide an inverter device capable of realizing exact protection of the winding of a motor. An inverter device for generating a pseudo alternating current by switching a direct current to drive a motor, comprises a controller that executes vector control on the basis of a secondary current applied to the motor. The controller calculates a current density from the secondary current to execute a predetermined protection operation on the basis of the calculated current density. The controller imposes a restriction on the operation frequency of the motor on the basis of the current density.

Highly Efficient DC Scroll Compressor

The scroll compressor is equipped with a Frame Compliance Mechanism that allows movement in the axial direction of the frame supporting the cradle scroll. This reduces both leaking and friction loss. allowing very high efficiency throughout the speed range.An air conditioner equipped with a compressor, an indoor heat exchanger and an outdoor heat exchanger includes: an inverter circuit that drives a motor of the compressor; an inverter-power detecting unit that detects power of the inverter circuit; a PWM-signal generating unit that inverter-current detecting unit generates PWM signals for controlling the inverter circuit; a voltage-command-value generating unit that outputs voltage command values to the PWM-signal generating unit; and an accumulation detecting unit that detects accumulation of a liquid refrigerant within the compressor and outputs to the voltage-command-value generating unit, wherein when accumulation of a liquid refrigerant within the compressor is detected, the voltage-command-value generating unit outputs the voltage command value so that power of the inverter circuit has a predetermined power value.
According to a conventional air conditioner, when a refrigerating cycle is stopped for a long period of time and a compressor is maintained at a low temperature, a liquid refrigerant accumulates in a compressor suction pipe-line, liquid compression occurs when the air conditioner is activated, and thus a shaft torque becomes excessive. This results in breakage of the compressor.
To provide a compressor driving device for an air conditioner that enables efficient heating from inside of a compressor when the compressor itself is at a low temperature, there has been known a compressor driving device for an air conditioner that applies a fixed alternating-current voltage, which cannot be followed by a movable part of the compressor and has a frequency higher than that of the normal operation, to the compressor at a regular time interval while the operation of the compressor is stopped, and continuously applies a fixed alternating-current voltage to the compressor when a current detecting unit detects a current value higher than a predetermined set value at that time.In order to solve the aforementioned problems, an air conditioner including a compressor, an indoor heat exchanger and an outdoor heat exchanger according to one aspect of the present invention is configured in such a manner as to include: an inverter circuit that drives a motor of the compressor; an inverter-power detecting unit that detects power of the inverter circuit; a PWM-signal generating unit that generates PWM signals for controlling the inverter circuit; a voltage-command-value generating unit that outputs voltage command values to the PWM-signal generating unit; and an accumulation detecting unit that detects accumulation of a liquid refrigerant within the compressor and outputs to the voltage-command-value generating unit, wherein when accumulation of a liquid refrigerant within the compressor is detected, the voltage-command-value generating unit outputs the voltage command value so that power of the inverter circuit has a predetermined power value.

Reluctance DC Rotor

The rotor is equipped with powerful neodymium magnets that use reluctance torque to produce magnetic torque for more efficient operation.
A neodymium magnet (also known as NdFeB, NIB or Neo magnet), the most widely used
type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed in 1982 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet made.

Rare earth magnets, made from alloys of rare earth elements, are substantially stronger than ceramic magnets or Alnico magnets. Adams offers them in block, ring or disc form, and in a variety of sizes and grades.

The tetragonal Nd2Fe14B crystal structure has exceptionally high uniaxial magnetocrystalline anisotropy (HA~7 teslas). This gives the compound the potential to have high coercivity (i.e., resistance to being demagnetized). The compound also has a high saturation magnetization (Js ~1.6 T or 16 kG) and typically 1.3 teslas. Therefore, as the maximum energy density is proportional to Js2, this magnetic phase has the potential for storing large amounts of magnetic energy (BHmax ~ 512 kJ/m3 or 64 MG·Oe), considerably more than samarium cobalt (SmCo) magnets, which were the first type of rare earth magnet to be commercialized. In practice, the magnetic properties of neodymium magnets depend on the alloy composition, microstructure, and manufacturing technique employed.

Some important properties used to compare permanent magnets are: remanence (Br), which measures the strength of the magnetic field; coercivity (Hci), the material's resistance to becoming demagnetized; energy product (BHmax), the density of magnetic energy; and Curie temperature (TC), the temperature at which the material loses its
magnetism. Neodymium magnets have higher remanence, much higher coercivity and energy product, but often lower Curie temperature than other types. Neodymium is alloyed with terbium and dysprosium in order to preserve its magnetic properties at high temperatures.

Strong as these strong magnets are, there are situations where another type of magnet might be preferable. A Neodymium magnet, the most common type of strong (rare earth) magnet, requires extremely high magnetizing fields, as well as a protective coating for certain applications.

Additionally, there are temperature constraints, and in all circumstances workers must always use caution when handling these magnets because of their exceptional magnetic force.

Grades of Neodymium magnets N35-N52 33M-48M 30H-45H 30SH-42SH 30UH-35UH 28EH-35EH.

Super-Quiet Technology Ultra-Silent Outdoor Unit

Inside the unit, the multi-angled heat exchanger has a modified fin shape that reduces air resistance for a smoother, quieter airflow. This lowers noise level to only 27dB(A) during normal operation for the new cassette units, making it one of the quietest indoor units in the industry.

MITSUBISHI ELECTRIC Mr.SLIM PKA-RP100KAL + MITSUBISHI ELECTRIC PUHZ-ZRP100VKA POWER INVERTER Technology Explained, MITSUBISHI ELECTRIC PUHZ-ZRP100VKA AIR-CONDITIONING APPARATUS with power receiver:

In an air-conditioning apparatus equipped with an outdoor unit having outdoor devices including a compressor that compresses a refrigerant, a flow switching valve that switches the flowing direction of the refrigerant, an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a first expansion valve that reduces the pressure of the refrigerant, an excess-refrigerant container that retains an excess refrigerant of the refrigerant, and a second expansion valve that reduces the pressure of the refrigerant; and an indoor unit having an indoor heat exchanger that exchanges heat between the refrigerant and indoor air, the air-conditioning apparatus includes an outdoor-heat-exchanger refrigerant injection port provided in a refrigerant pipe that is directly connected to the outdoor heat exchanger, and an excess-refrigerant-container refrigerant injection port provided in a refrigerant pipe that is directly connected to the excess-refrigerant container.

1. An air-conditioning apparatus comprising: an outdoor unit having outdoor devices including a compressor that compresses a refrigerant, a flow switching valve that switches a flowing direction of the refrigerant, an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a first expansion valve that reduces pressure of the refrigerant, an excess-refrigerant container that retains an excess refrigerant of the refrigerant, and a second expansion valve that reduces the pressure of the refrigerant; and an indoor unit having an indoor heat exchanger that exchanges heat between the refrigerant and indoor air, wherein the outdoor devices and the indoor heat exchanger are sequentially connected by refrigerant pipes so that a refrigeration cycle is formed, wherein the air-conditioning apparatus further comprises an outdoor-heat-exchanger refrigerant injection port provided in the refrigerant pipe that is directly connected to the outdoor heat exchanger, and an excess-refrigerant-container refrigerant injection port provided in the refrigerant pipe that is directly connected to the excess-refrigerant container.

2. The air-conditioning
apparatus of claim 1, wherein the excess-refrigerant container refrigerant injection port is provided in both or at least either one of the refrigerant pipe extending between the first expansion valve and the excess-refrigerant container and the refrigerant pipe extending between the second expansion valve and the excess-refrigerant container.

3. The air-conditioning apparatus of claim 1, wherein the outdoor-heat-exchanger refrigerant injection port is provided in both or at least either one of the refrigerant pipe extending between the flow switching valve and the outdoor heat exchanger and the refrigerant pipe extending between the first expansion valve and the outdoor heat exchanger.

4. The air-conditioning apparatus of claim 1, wherein the indoor unit comprises a plurality of indoor units.

5. The air-conditioning apparatus of claim 1, further comprising a heat exchanging unit that exchanges heat between the refrigerant flowing through the refrigerant pipe connected to a suction side of the compressor and the refrigerant retained in the excess-refrigerant container, wherein the refrigerant to be suctioned into the compressor is suctioned into the compressor after exchanging heat with the refrigerant retained in the excess-refrigerant container at the heat exchanging unit.

6. The air-conditioning apparatus of claim 2, wherein the outdoor-heat-exchanger refrigerant injection port is provided in both or at least either one of the refrigerant pipe extending between the flow switching valve and the outdoor heat exchanger and the refrigerant pipe extending between the first expansion valve and the outdoor heat exchanger.

7. The air-conditioning apparatus of claim 2, further comprising a heat exchanging unit that exchanges heat between the refrigerant flowing through the refrigerant pipe connected to a suction side of the compressor and the refrigerant retained in the excess-refrigerant container, wherein the refrigerant to be suctioned into the compressor is suctioned into the compressor after exchanging heat with the refrigerant retained in the excess-refrigerant container at the heat exchanging unit.

8. The air-conditioning apparatus of claim 3, further comprising a heat exchanging unit that exchanges heat between the refrigerant flowing through the refrigerant pipe connected to a suction side of the compressor and the refrigerant retained in the excess-refrigerant container, wherein the refrigerant to be suctioned into the compressor is suctioned into the compressor after exchanging heat with the refrigerant retained in the excess-refrigerant container at the heat exchanging unit.

9. The air-conditioning apparatus of claim 4, further comprising a heat exchanging unit that exchanges heat between the refrigerant flowing through the refrigerant pipe connected to a suction side of the compressor and the refrigerant retained in the excess-refrigerant container, wherein the refrigerant to be suctioned into the compressor is suctioned into the compressor after exchanging heat with the refrigerant retained in the excess-refrigerant container at the heat exchanging unit.

10. The air-conditioning apparatus of claim 6, further comprising a heat exchanging unit that exchanges heat between the refrigerant flowing through the refrigerant pipe connected to a suction side of the compressor and the refrigerant retained in the excess-refrigerant container, wherein the refrigerant to be suctioned into the compressor is suctioned into the compressor after exchanging heat with the refrigerant retained in the excess-refrigerant container at the heat exchanging unit.

Description:

TECHNICAL FIELD
The present invention relates to air-conditioning apparatuses, and in particular, relates to a configuration for injecting a refrigerant into a refrigerant circuit of an air-conditioning apparatus.

BACKGROUND ART
A common air-conditioning apparatus is equipped with an outdoor unit having a compressor, a four-way valve serving as flow switching means for switching the flowing direction of a refrigerant, an outdoor heat exchanger and a pressure-reducing capillary tube connected to an outlet of the outdoor heat exchanger, and an electronic expansion valve that further reduces the pressure of the refrigerant after having passed through the capillary tube; and an indoor unit having an indoor heat exchanger. The aforementioned devices contained in the outdoor unit and the indoor unit are sequentially connected by refrigerant pipes in the form of a circuit, and the refrigerant circulates through the refrigerant circuit, whereby a refrigeration cycle is formed. When the indoor heat exchanger operates as an evaporator and the outdoor heat exchanger operates as a condenser, indoor cooling is achieved. On the other hand, when the indoor heat exchanger operates as a condenser and the outdoor heat exchanger operates as an evaporator, indoor heating is achieved. The four-way valve provided at the discharge side of the compressor switches the flowing direction of the refrigerant so that the refrigerant discharged from the compressor is condensed by the indoor heat exchanger or the outdoor heat exchanger. Fans are disposed near the indoor heat exchanger and the outdoor heat exchanger and send indoor air and outdoor air thereto, respectively.
In recent years, outdoor units that can be used in various ways and can be connected to various types of indoor units in accordance with users' demands are in demand. In this case, since the capacity of and the amount of air for the indoor heat exchanger vary depending on the type of indoor unit, the amount of refrigerant for allowing the refrigeration cycle to exhibit maximum performance would also vary. In order to properly adjust the amount of refrigerant circulating through the refrigerant circuit, an excess-refrigerant container is provided in the refrigerant circuit for retaining an excess refrigerant. A receiver serving as this excess-refrigerant container is often disposed in a suction pipe of the compressor or at a position where a liquid refrigerant exists, such as a position between an outlet of the condenser and an inlet of the evaporator.

In the air-conditioning apparatus having such a configuration, if a large amount of refrigerant that covers the entire refrigerant circuit is to be injected into the refrigerant circuit during production or maintenance of the air-conditioning apparatus, the refrigerant is injected from a refrigerant injection port provided in the refrigerant circuit. In particular, a configuration is disclosed in which the refrigerant is injected into the refrigerant circuit from a refrigerant injection port provided in the suction pipe of the compressor, an inlet pipe of a heat exchanger, or an outlet pipe of the heat exchanger (e.g., see Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 5-312439 (paragraph 0025, FIG. 5)

SUMMARY OF INVENTION

Technical Problem
Among the devices constituting the refrigerant circuit of the air-conditioning apparatus, the refrigerant is retained mainly in the compressor, the heat exchanger, and the excess-refrigerant container. Therefore, upon injection of the refrigerant into the refrigerant circuit, it is necessary to inject the refrigerant so that the refrigerant flows into the devices in which a large amount of refri

gerant is to be retained. In the apparatus in the conventional art, the refrigerant is injected from a certain location of the refrigerant circuit, such as from the refrigerant injection port provided in the suction pipe of the compressor, the inlet pipe of the heat exchanger, or the outlet pipe of the heat exchanger. Even if the refrigerant is injected from the refrigerant injection port provided at any of these locations, the electronic expansion valve, the capillary tube, and the like that are provided for reducing the pressure of the refrigerant in the refrigerant circuit act as pressure-reducing members, making it impossible to reliably inject the refrigerant into the aforementioned devices, in which the refrigerant is to be mainly retained, in a well-balanced manner within a short period of time. Specifically, it takes time for the refrigerant to pass through the pressure-reducing members, thus requiring a long time for the refrigerant injection process. In addition, the pressure-reducing members act as resistance that causes the refrigerant to be injected lopsidedly to a specific device, which is a problem in that a liquid-sealed state may possibly occur. When this liquid-sealed state occurs, a liquid refrigerant expands in response to a temperature change, sometimes causing an abnormal increase in internal pressure.
Furthermore, with regard to a separate-type air-conditioning apparatus in which the indoor unit installed indoors and the outdoor unit installed outdoors are separated from each other, there is a problem in that, when an amount of refrigerant required in the entire refrigerant circuit is to be injected into the outdoor unit, an optimal position for a refrigerant injection port for reliably injecting the refrigerant in a well-balanced manner is not clearly defined.
The present invention has been made to solve the aforementioned problems and an object thereof is to provide an air-conditioning apparatus in which an amount of refrigerant required in a refrigerant circuit is reliably injected into the refrigerant circuit in a well-balanced manner within a short period of time at an outdoor-unit side so that the occurrence of a liquid-sealed state can be prevented.

Solution to Problem
An air-conditioning apparatus according to the present invention includes an outdoor unit having outdoor devices including a compressor that compresses a refrigerant, a flow switching valve that switches a flowing direction of the refrigerant, an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a first expansion valve that reduces pressure of the refrigerant, an excess-refrigerant container that retains an excess refrigerant of the refrigerant, and a second expansion valve that reduces the pressure of the refrigerant; and an indoor unit having an indoor heat exchanger that exchanges heat between the refrigerant and indoor air. The outdoor devices and the indoor heat exchanger are sequentially connected by refrigerant pipes so that a refrigeration cycle is formed. The air-conditioning apparatus further includes an outdoor-heat-exchanger refrigerant injection port provided in the refrigerant pipe that is directly connected to the outdoor heat exchanger, and an excess-refrigerant-container refrigerant injection port provided in the refrigerant pipe that is directly connected to the excess-refrigerant container.

Advantageous Effects of Invention
In the air-conditioning apparatus according to the present invention, the refrigerant is injected into the outdoor heat exchanger from the outdoor-heat-exchanger refrigerant injection port, and the refrigerant is injected into the excess-refrigerant container from the excess-refrigerant-container refrigerant injection port, so that the refrigerant is injected into the outdoor heat exchanger and the excess-refrigerant container, which have large capacities, without the refrigerant being retained lopsidedly in one device in the refrigerant circuit. Thus, an amount of refrigerant required in the refrigerant circuit can be reliably injected thereto in a well-balanced manner within a short period of time, whereby a safe air-conditioning apparatus that prevents the occurrence of a liquid-sealed state is obtained.

BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a pressure-versus-specific-enthalpy graph of a refrigeration cycle according to Embodiment 1 of the present invention.
FIG. 3 includes schematic diagrams illustrating refrigerant injection ports according to Embodiment 1 of the present invention.
FIG. 4 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to Embodiment 1 of the present invention.
FIG. 5 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to Embodiment 1 of the present invention.
FIG. 6 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to Embodiment 1 of the present invention.
FIG. 7 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 2 of the present invention.
FIG. 8 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 3 of the present invention.
FIG. 9 is a pressure-versus-specific-enthalpy graph of a refrigeration cycle according to Embodiment 3 of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiment 1

FIG. 1 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 1 of the present invention. This air-conditioning apparatus has an outdoor unit 1 and an indoor unit 8. The outdoor unit 1 contains outdoor devices, which include a compressor 2 that compresses a refrigerant; a four-way valve 3 serving as a flow switching valve that switches the flowing direction of the refrigerant; an outdoor heat exchanger 4 that exchanges heat between the refrigerant and outdoor air; a pressure-reducing capillary tube 5 connected to an outlet of the outdoor heat exchanger 4; a first expansion valve 11 and a second expansion valve 13, in this case, a first electronic expansion valve 11 and a second electronic expansion valve 13 serving as electronic pressure-reducing means, which further reduce the pressure of the refrigerant reduced in pressure by the capillary tube 5; and an intermediate-pressure receiver 12 provided between the first electronic expansion valve 11 and the second electronic expansion valve 13 and serving as an excess-refrigerant container that retains an excess refrigerant. The indoor unit 8 contains an indoor heat exchanger 9 that exchanges heat between the refrigerant and indoor air. The outdoor devices (i.e., the compressor 2, the four-way valve 3, the outdoor heat exchanger 4, the capillary tube 5, the first electronic expansion valve 11, the intermediate-pressure receiver 12, and the second electronic expansion valve 13) constituting the outdoor unit 1 and the indoor heat exchanger 9 are sequentially connected by refrigerant pipes. These refrigerant pipes are filled with, for example, R410A, which is an HFC-based refrigerant, so that a refrigeration cycle is formed. Furthermore, an outdoor-heat-exchanger charge port 14 serving as an outdoor-heat-exchanger refrigerant injection port is provided between the four-way v
alve 3 and the outdoor heat exchanger 4, and a receiver charge port 15 serving as an excess-refrigerant-container refrigerant injection port is provided between the intermediate-pressure receiver 12 and the second electronic expansion valve 13. The refrigerant is injected into the refrigerant circuit via the outdoor-heat-exchanger charge port 14 and the receiver charge port 15. Fans 7 and 10 are provided near the outdoor heat exchanger 4 and the indoor heat exchanger 9 and send outdoor air and indoor air to the outdoor heat exchanger 4 and the indoor heat exchanger 9, respectively, so as to make the refrigerant and the air exchange heat with each other at the outdoor heat exchanger 4 and the indoor heat exchanger 9. In the drawing, arrows denote the circulating direction of the refrigerant. Specifically, solid-line arrows correspond to the case where an indoor cooling operation is performed, whereas dotted-line arrows correspond to the case where an indoor heating operation is performed. When this air-conditioning apparatus is performing a cooling operation or a heating operation, the outdoor-heat-exchanger charge port 14 and the receiver charge port 15 are closed and are not involved with the operation of the refrigeration cycle.

FIG. 2 is a pressure-versus-specific-enthalpy graph of the refrigeration cycle according to Embodiment 1. The following description based on FIGS. 1 and 2 relates to the refrigeration cycle in the case where the air-conditioning apparatus is in operation. In FIG. 2, the abscissa axis denotes the specific enthalpy, whereas the ordinate axis denotes the pressure. In the case where an indoor cooling operation is performed, black dots (A, B, C, D, and E) indicate the state of the refrigerant at positions denoted by black dots (A, B, C, D, and E), respectively, in FIG. 1. In the case where a heating operation is performed, black dots (a, b, c, d, and e) indicate the state of the refrigerant at positions denoted by black dots (a, b, c, d, and e), respectively, in FIG. 1.

The cooling operation will be described below. The indoor heat exchanger 9 contained in the indoor unit 8 operates as an evaporator, and the outdoor heat exchanger 4 contained in the outdoor unit 1 operates as a condenser. A low-temperature low-pressure refrigerant (A) is suctioned into the compressor 2 and is discharged therefrom as a high-temperature high-pressure gas refrigerant (B). Subsequently, the high-temperature high-pressure gas refrigerant (B) travels through the four-way valve 3 and transfers heat to outdoor air sent by the fan 7 by exchanging heat with the outdoor air at the outdoor heat exchanger 4 serving as a condenser, so that the temperature of the refrigerant itself decreases. Then, the refrigerant is slightly reduced in pressure (C) by the capillary tube 5 disposed at the outlet of the outdoor heat exchanger 4, and is further reduced in pressure by the first electronic expansion valve 11, thereby becoming an intermediate-temperature intermediate-pressure two-phase gas-liquid refrigerant (D). This intermediate-temperature intermediate-pressure refrigerant (D) flows into the intermediate-pressure receiver 12, and a portion of the refrigerant is retained therein in accordance with the opening degree of the second electronic expansion valve 13, whereas the remaining portion of the refrigerant flows out from the intermediate-pressure receiver 12 and is reduced in pressure by the second electronic expansion valve 13 so as to become a low-temperature low-pressure refrigerant (E), which then circulates from the outdoor unit 1 to the indoor unit 8. In the indoor unit 8, the refrigerant removes heat from indoor air sent by the fan 10 by exchanging heat with the indoor air at the indoor heat exchanger 9 operating as an evaporator, whereby indoor cooling is performed at this point. The refrigerant flowing out from the indoor unit 8 flows into the outdoor unit 1 again, travels through the four-way valve 3, and is suctioned into the compressor 2 again as a low-temperature low-pressure refrigerant (A). The above-described series of cycle is repeated.
In the case of the heating operation, the four-way valve 3 is switched so that the refrigerant flows through a circuit denoted by dotted lines in the four-way valve 3. The refrigerant discharged from the compressor 2 travels through the four-way valve 3 so as to flow to the indoor unit 8. The indoor heat exchanger 9 operates as a condenser, whereas the outdoor heat exchanger 4 operates as an evaporator. Specifically, the refrigerant circulates through the refrigerant circuit in a direction inverse to that in the cooling operation so that indoor heating is performed. The changes in the state of the refrigeration cycle are the same as those in the cooling operation. In the indoor heat exchanger 9, the refrigerant transfers heat to indoor air so that the state of the refrigerant changes from (b) to (c). Subsequently, the refrigerant is reduced to intermediate pressure by the second electronic expansion valve 13, and an intermediate-temperature intermediate-pressure refrigerant (d) is retained in the intermediate-pressure receiver 12. The refrigerant flowing out from the intermediate-pressure receiver 12 is reduced to a low pressure (e) by the first electronic expansion valve 11 and flows into the outdoor heat exchanger 4 via the capillary tube 5. Then, after exchanging heat with outdoor air, the refrigerant becomes a low-temperature low-pressure refrigerant (a), which is then suctioned into the compressor 2.
The volume and the operational state of the indoor unit 8 vary depending on, for example, users' environment. Therefore, a configuration that allows not only a predetermined indoor unit but also an indoor unit with a different volume or a different number of indoor units to be connectable to a single outdoor unit is demanded. In that case, since the capacity of and the amount of air for the indoor heat exchanger vary from indoor unit to indoor unit, the amount of refrigerant required for allowing the refrigeration cycle to exhibit maximum performance would also vary. In addition, the amount of required refrigerant differs between the heating operation and the cooling operation. In Embodiment 1, in order to properly adjust the amount of refrigerant circulating through the refrigerant circuit, the intermediate-pressure receiver 12 is provided as an excess-refrigerant container, and this intermediate-pressure receiver 12 is configured to retain an excess refrigerant in an intermediate-temperature intermediate-pressure state during operation.
In the refrigeration cycle, the condensing temperature and the evaporating temperature of the refrigerant will respectively be referred to as “high temperature” and “low temperature”, and the condensing pressure and the evaporating pressure of the refrigerant will respectively be referred to as “high pressure” and “low pressure”. An intermediate temperature is a temperature that is lower than the condensing temperature of the refrigerant but higher than the evaporating temperature, and an intermediate pressure is a pressure that is lower than the condensing pressure of the refrigerant but higher than the evaporating pressure. Specifically, the temperature and the pressure of the refrigerant retained in the intermediate-pressure receiver 12 vary depending on the refrigerant circulating through the refrigerant circuit.
The intermediate-pressure receiver 12 is provided at a position that is located between the outdoor heat exchanger 4 and the indoor uni

t 8 and where an intermediate-pressure liquid refrigerant exists. In detail, a refrigerant flowing out from a heat exchanger operating as a condenser is reduced in pressure in two stages by at least two pressure-reducing means, that is, the first electronic expansion valve 11 and the second electronic expansion valve 13, and an intermediate-temperature intermediate-pressure refrigerant after being reduced in pressure by the upstream-side pressure-reducing means (i.e., the first electronic expansion valve 11 during cooling or the second electronic expansion valve 13 during heating) is retained in the intermediate-pressure receiver 12. Specifically, by disposing the first electronic expansion valve 11 and the second electronic expansion valve 13 in front of and behind the intermediate-pressure receiver 12, the intermediate-temperature intermediate-pressure refrigerant can be retained in the intermediate-pressure receiver 12 even if the circulating direction of the refrigerant flowing through the refrigerant pipes is reversed between the cooling operation and the heating operation.
With the intermediate-pressure receiver 12 provided between the first electronic expansion valve 11 and the second electronic expansion valve 13, the electronic expansion valve located upstream of the intermediate-pressure receiver 12 in the circulating direction of the refrigerant (i.e., the first electronic expansion valve 11 during cooling or the second electronic expansion valve 13 during heating) reduces the pressure of a high-pressure refrigerant to an intermediate pressure. Furthermore, the opening degree of the electronic expansion valve located downstream of the intermediate-pressure receiver 12 in the circulating direction of the refrigerant (i.e., the second electronic expansion valve 13 during cooling or the first electronic expansion valve 11 during heating) is adjusted so that the intermediate-pressure refrigerant is reduced to a low pressure and the amount of liquid refrigerant retained in the intermediate-pressure receiver 12 is optimized. For example, when a container that retains an excess refrigerant is installed at a position where a high-temperature refrigerant may possibly flow into the container, it is desired that the container have high resistance to pressure. In Embodiment 1, since an intermediate-temperature intermediate pressure refrigerant (D or d) reduced in pressure by an electronic expansion valve provided upstream of the intermediate-pressure receiver 12 is retained in the intermediate-pressure receiver 12, a refrigerant reduced in pressure to some extent is made to flow into the intermediate-pressure receiver 12. This allows for improved reliability without requiring the pressure resistance as in the configuration that retains a high-pressure refrigerant.
The following description relates to a

case where a refrigerant is injected into the refrigerant circuit of the air-conditioning apparatus during production thereof. In view of the volumes (capacities) of the devices constituting the air-conditioning apparatus, the outdoor heat exchanger 4 normally has the largest volume, the intermediate-pressure receiver 12 has the second largest volume, and then the indoor heat exchanger 9 and the compressor 2 and so on. For example, the outdoor heat exchanger 4 has a volume of about 5000 cc, the intermediate-pressure receiver 12 has a volume of about 3000 cc, the indoor heat exchanger 9 has a volume of about 500 to 1000 cc, and the compressor 2 has a volume of about 500 cc. In particular, in a separate-type air-conditioning apparatus in which the indoor unit 8 and the outdoor unit 1 are separated from each other, a refrigerant is injected into the outdoor unit 1 in advance at a factory, etc. At an installation location, operation is performed after connecting the indoor unit 8 to the refrigerant pipes of the outdoor unit 1. This allows for a safe and easy process in view of assembly and installation. Therefore, upon injection of a refrigerant into the outdoor unit 1, a large amount of refrigerant that can cover the entire refrigerant circuit is injected, meaning that a sufficient amount of refrigerant that at least fills the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 having large capacities needs to be reliably injected. In addition, the refrigerant needs to be injected in a well-balanced manner in accordance with the capacities of the outdoor heat exchanger 4 and the intermediate-pressure receiver 12.

FIG. 3 includes schematic diagrams illustrating an example of the outdoor-heat-exchanger charge port 14 serving as an outdoor-heat-exchanger refrigerant injection port and the receiver charge port 15 serving as an intermediate-receiver refrigerant injection port, which are used for injecting a refrigerant into the refrigerant circuit. FIG. 3(a) illustrates the outdoor-heat-exchanger charge port 14 provided in a refrigerant pipe 16a that is directly connected to the outdoor heat exchanger 4. To the refrigerant pipe 16a is connected a branch pipe 17 whose one end is connected to a valve 18 having an opening-and-closing function. The valve 18 is opened and is attached to, for example, a refrigerant pipe 19 or a refrigerant hose (denoted by a dotted line) connected to a refrigerant container (not shown) so that the refrigerant in the refrigerant container is injected into the outdoor heat exchanger 4 from the refrigerant pipe 16a via the refrigerant pipe 19, the valve 18, and the branch pipe 17. After injecting the refrigerant, the valve 18 is closed.
The refrigerant pipe directly connected to the outdoor heat exchanger 4 is a refrigerant pipe that is connected to a pipe in the outdoor heat exchanger 4 without any intervening devices that are constituent of e the refrigerant circuit, for example, pressure-reducing members such as the capillary tube 5 and the electronic expansion valves 11 and 13. The outdoor-heat-exchanger charge port 14 is connected to the outdoor heat exchanger 4 only via the refrigerant pipe.
The receiver charge port 15 provided in a refrigerant pipe 16b that is directly connected to the intermediate-pressure receiver 12 has a similar configuration. In FIG. 3(b), a branch pipe 17 whose one end is connected to a valve 18 having an opening-and-closing function is connected to the refrigerant pipe 16b directly connected to the intermediate-pressure receiver 12. This valve 18 is opened and, for example, a refrigerant pipe 19 (denoted by a dotted line) connected to a refrigerant container (not shown) is attached to the valve 18 so that the refrigerant in the refrigerant container is injected into the intermediate-pressure receiver 12 from the refrigerant pipe 16b via the refrigerant pipe 19, the valve 18, and the branch pipe 17. After injection of the refrigerant, the valve 18 is closed.
Similar to the above, the refrigerant pipe directly connected to the intermediate-pressure receiver 12 is a refrigerant pipe that is connected to a pipe in the intermediate-pressure receiver 12 without any intervening devices that are the constituents of the refrigerant circuit, for example, pressure-reducing members such as the capillary tube 5 and the electronic expansion valves 11 and 13. The receiver charge port 15 is connected to the intermediate-pressure receiver 12 only via the refrigerant pipe.
In a configuration provided with a single charge port in the entire refrigerant circuit, as in the apparatus in the conventional art, for example, if the refrigerant is to be injected into the refrigerant circuit from the charge port 14 provided near the outdoor heat exchanger 4, the existence of the capillary tube 5 and the first electronic expansion valve 11 serving as pressure-reducing members creates resistance that makes it difficult for the refrigerant to move and flow into the intermediate-pressure receiver 12, causing most of the refrigerant to be retained in the outdoor heat exchanger 4. Because the upstream side and the downstream side of the intermediate-pressure receiver 12 are respectively connected to the electronic expansion valves 11 and 13, it is difficult to inject the refrigerant into the intermediate-pressure receiver 12 if the charge port is provided near the outdoor heat exchanger 4, or it is difficult to inject the refrigerant into the outdoor heat exchanger 4 if the charge port is provided near the intermediate-pressure receiver 12. Although the refrigerant may gradually flow into the intermediate-pressure receiver 12 or the outdoor heat exchanger 4 by passing through the pressure-reducing members, the injection time is too long.
In contrast, in Embodiment 1, the refrigerant is reliably injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14. Furthermore, since there are no pressure-reducing members between the outdoor-heat-exchanger charge port 14 and the outdoor heat exchanger 4, the refrigerant is injected smoothly within a short period of time. Likewise, the refrigerant is reliably injected into the intermediate-pressure receiver 12 from the receiver charge port 15, and since there are no pressure-reducing members between the receiver charge port 15 and the intermediate-pressure receiver 12, the refrigerant is injected smoothly w

ithin a short period of time. Accordingly, since an amount of refrigerant required in the refrigerant circuit is distributively injected into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12, the occurrence of a liquid-sealed state caused by the refrigerant being injected lopsidedly to a specific device in the refrigerant circuit is prevented, whereby the refrigerant is safely injected.
Furthermore, a required amount of refrigerant can be injected from the outdoor-heat-exchanger charge port 14 in accordance with the capacity of the outdoor heat exchanger 4. Likewise, a required amount of refrigerant can be injected from the receiver charge port 15 in accordance with the capacity of the intermediate-pressure receiver 12. Therefore, an amount of refrigerant required in the refrigerant circuit can be distributively injected into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 in a well-balanced manner. Accordingly, a required amount of refrigerant can be injected in accordance with the different capacities of the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 constituting the refrigerant circuit.
Either of the refrigerant injection processes may precede the other. For example, the refrigerant may be injected into the intermediate-pressure receiver 12 from the receiver charge port 15 after the injection of the refrigerant into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14. Alternatively, the refrigerant may be injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14 after the injection of the refrigerant into the intermediate-pressure receiver 12 from the receiver charge port 15. Furthermore, injecting the refrigerant simultaneously into the intermediate-pressure receiver 12 and the outdoor heat exchanger 4 shortens the time required for the refrigerant injection process.
The configurations of the outdoor-heat-exchanger charge port 14 and the receiver charge port 15 are not limited to those described above, and alternative configurations are permissible. For example, if the refrigerant is to be preliminarily injected into the refrigerant circuit during the manufacturing process, the branch pipes may simply be connected to the refrigerant pipes and be closed by, for example, brazing after the refrigerant is injected through these branch pipes. In this case, if an injection is necessary again, the injection process can be performed again by cutting the brazed sections.
Accordingly, the outdoor-heat-exchanger charge port 14 is provided in the refrigerant pipe that is directly connected to the large-capacity outdoor heat exchanger 4 constituting the refrigerant circuit, and the receiver charge port 15 is provided in

the refrigerant pipe that is directly connected to the intermediate-pressure receiver 12, so that the refrigerant can be reliably injected into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12, thereby allowing for improved reliability of the refrigerant injection process and also achieving a shorter injection time. In particular, an amount of refrigerant required in the refrigerant circuit can be injected thereto at the outdoor-unit side. Although the refrigerant injection process performed during the manufacturing process is described above, the present invention is not limited to this. For example, even if there is a need to additionally inject the refrigerant into the refrigerant circuit after installation, an amount of refrigerant required in the refrigerant circuit can be injected from the outdoor-heat-exchanger charge port 14 and the receiver charge port 15, whereby the refrigerant can be injected reliably in a well-balanced manner within a short period of time, advantageously.
According to Embodiment 1, the air-conditioning apparatus includes the outdoor unit 1 having outdoor devices, which include the compressor 2 that compresses the refrigerant, the flow switching valve 3 that switches the flowing direction of the refrigerant, the outdoor heat exchanger 4 that exchanges heat between the refrigerant and outdoor air, the first expansion valve 11 that reduces the pressure of the refrigerant, the excess-refrigerant container 12 that retains an excess refrigerant of the refrigerant, and the second expansion valve 13 that reduces the pressure of the refrigerant; and the indoor unit 8 having the indoor heat exchanger 9 that exchanges heat between the refrigerant and indoor air. The outdoor devices and the indoor heat exchanger 9 are sequentially connected by the refrigerant pipes so that a refrigeration cycle is formed. The air-conditioning apparatus further includes the outdoor-heat-exchanger refrigerant injection port 14 provided in the refrigerant pipe 16a that is directly connected to the outdoor heat exchanger 4, and the excess-refrigerant-container refrigerant injection port 15 provided in the refrigerant pipe 16b that is directly connected to the excess-refrigerant container 12. Thus, the refrigerant can also be injected into the large-capacity excess-refrigerant container 12 in a well-balanced manner without a large amount of refrigerant being lopsidedly injected only into the outdoor heat exchanger 4. Consequently, an air-conditioning apparatus is provided in which an amount of refrigerant required in the refrigerant circuit can be reliably and safely injected thereto within a short period of time, advantageously.

FIG. 4 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to the present invention. With regard to the position of the outdoor-heat-exchanger charge port, in the configuration in FIG. 1, the outdoor-heat-exchanger charge port 14 is provided in the refrigerant pipe 16a that serves as a refrigerant pipe directly connected to the outdoor heat exchanger 4 and that extends between the four-way valve 3 and the outdoor heat exchanger 4. In the exemplary configuration shown in FIG. 4, a capillary tube is not provided between the outdoor heat exchanger 4 and the first electronic expansion valve 11, and an outdoor-heat-exchanger charge port 20 is provided in a refrigerant pipe 16d extending between the outdoor heat exchanger 4 and the first electronic expansion valve 11.
This configuration is similar to that in FIG. 1 in that the refrigerant can be injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 20 and in that the refrigerant can be injected into the intermediate-pressure receiver 12 from the receiver charge port 15. A required amount of refrigerant can be reliably injected in a well-balanced manner without the refrigerant being lopsided to one of the outdoor heat exchanger 4 and the intermediate-pressure receiver 12, which are large-capacity devices among the devices constituting the outdoor unit 1, thereby allowing for improved reliability of the refrigerant injection process and also achieving a shorter injection time.
FIG. 5 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to the present invention. With regard to the position of the receiver charge port, in the configurations in FIG. 1 and FIG. 4, the receiver charge port 15 is provided in the refrigerant pipe 16b that serves as a refrigerant pipe directly connected to the intermediate-pressure receiver 12 and that extends between the intermediate-pressure receiver 12 and the second electronic expansion valve 13.

In the exemplary configuration shown in FIG. 5, a receiver charge port 21 is provided in a refrigerant pipe 16c extending between the first electronic expansion valve 11 and the intermediate-pressure receiver 12.
This configuration is similar to that in FIG. 1 in that the refrigerant can be injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14 and in that the refrigerant can be injected into the intermediate-pressure receiver 12 from the receiver charge port 21. A required amount of refrigerant can be reliably injected in a well-balanced manner without the refrigerant being lopsided to one of the outdoor heat exchanger 4 and the intermediate-pressure receiver 12, which are large-capacity devices among the devices constituting the outdoor unit 1, thereby allowing for improved reliability of the refrigerant injection process and also achieving a shorter injection time.
By providing the receiver charge port 21 in the refrigerant pipe 16c extending between the first electronic expansion valve 11 and the intermediate-pressure receiver 12 in the configuration in FIG. 4, a similar advantage can be achieved.

FIG. 6 is a schematic diagram illustrating another exemplary configuration of the air-conditioning apparatus according to the present invention. In this exemplary configuration, three charge ports 14, 15, and 21 are provided. Specifically, the outdoor-heat-exchanger charge port 14 is provided in the refrigerant pipe 16a directly connected to the outdoor heat exchanger 4, the receiver charge port 15 is provided in one refrigerant pipe 16b directly connected to the intermediate-pressure receiver 12, and the receiver charge port 21 is provided in the other refrigerant pipe 16c directly connected to the intermediate-pressure receiver 12. The refrigerant is injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14, and the refrigerant is injected into the intermediate-pressure receiver 12 from the two receiver charge ports 15 and 21. In this exemplary configuration, because the refrigerant can be injected into the intermediate-pressure receiver 12 simultaneously from the two receiver charge ports 15 and 21, the time required for the process of filling the intermediate-pressure receiver 12 with the refrigerant can be shortened, whereby a sufficient amount of refrigerant can be reliably injected into the refrigerant circuit.
Furthermore, in the case where the outdoor heat exchanger 4 and the first electronic expansion valve 11 are connected by the refrigerant pipe 16d as in

FIG. 4, two outdoor-heat-exchanger charge ports 14 and 20 may be provided. By injection of the refrigerant into the outdoor heat exchanger 4 from the two outdoor-heat-exchanger charge ports 14 and 20, the time required for the process of filling the outdoor heat exchanger 4 with the refrigerant can be shortened, whereby a sufficient amount of refrigerant can be reliably injected into the refrigerant circuit.
According to Embodiment 1, the excess-refrigerant-container refrigerant injection port 15 or 21 is provided for both or at least either one of the refrigerant pipe 16c, extending between the first expansion valve 11 and the excess-refrigerant container 12, and the refrigerant pipe 16b, extending between the second expansion valve 13 and the excess-refrigerant container 12, whereby an air-conditioning apparatus is obtained in which a required amount of refrigerant can be reliably injected into the intermediate-pressure receiver 12 within a short period of time, advantageously.
Furthermore, the outdoor-heat-exchanger refrigerant injection port 14 or 20 is provided for at least one of or each of the refrigerant pipe 16a extending between the flow switching valve 3 and the outdoor heat exchanger 4 and the refrigerant pipe 16d extending between the first expansion valve 11 and the outdoor heat exchanger 4, whereby an air-conditioning apparatus is obtained in which a required amount of refrigerant can be reliably injected into the outdoor heat exchanger 4 within a short period of time, advantageously.

Embodiment 2

FIG. 7 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 2 of the present invention. In the drawing, reference numerals or characters that are the same as those in FIG. 1 denote the same or equivalent components. The configuration of Embodiment 2 is one to which a plurality of, that is, n (which is an integer greater than 1) number of indoor units 8-1 to 8-n are connectable. In the configuration, branch sections 22a and 22b of the refrigerant circuit are provided in the outdoor unit 1, and n number of second electronic expansion valves 13-1 to 13-n that respectively correspond to the indoor units 8-1 to 8-n are provided. In this case, the outdoor-heat-exchanger charge port 14 is provided in the refrigerant pipe 16a that is directly connected to the outdoor heat exchanger 4, and the receiver charge port 15 is provided in the refrigerant pipe 16b that is directly connected to the intermediate-pressure receiver 12. In the drawing, solid-line arrows denote the circulating direction of the refrigerant when a cooling operation is performed by the indoor units 8, and dotted-line arrows denote the circulating direction of the refrigerant when a heating operation is performed by the indoor units 8.
In the case where the plurality of indoor units 8-1 to 8-n are provided, indoor heat exchangers 9-1 to 9-n provided therein are connected in parallel to the outdoor heat exchanger 4, and the refrigerant pipes are ramified into n number of refrigerant pipes at the branch sections 22a and 22b. The amount of refrigerant flowing through the indoor heat exchangers 9-1 to 9-n is adjusted by the second electronic expansion valves 13-1 to 13-n provided in the respective refrigerant pipes.
Because the configuration according to Embodiment

2 is provided with the plurality of indoor units 8-1 to 8-n, a larger amount of refrigerant is required in the refrigerant circuit that achieves this configuration, as compared with that in Embodiment 1. For example, if all of the indoor units 8-1 to 8-n operate at the same time, the outdoor unit 1 would be constituted of an outdoor heat exchanger 4 with a large capacity in correspondence with the plurality of indoor heat exchangers 9-1 to 9-n in operation. Therefore, the amount of refrigerant required in the refrigerant circuit is larger than that in the configuration provided with a single indoor unit 8, meaning that a large amount of refrigerant is injected into the refrigerant circuit. However, there is also a case where only one of the indoor units 8-1 to 8-n operates. In this case, the amount of refrigerant circulating through the refrigerant circuit is small, resulting in a large amount of excess refrigerant. For this reason, a large amount of excess refrigerant becomes retained in the intermediate-pressure receiver 12, making it necessary for the intermediate-pressure receiver 12 to have a large capacity. Specifically, in the air-conditioning apparatus equipped with the plurality of indoor units 8-1 to 8-n, the outdoor heat exchanger 4 and

the intermediate-pressure receiver 12 provided have larger capacities than those in the configuration in FIG. 1.
In the air-conditioning apparatus equipped with the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 that have large capacities, the refrigerant is injected into the outdoor heat exchanger 4 from the outdoor-heat-exchanger charge port 14 provided in the refrigerant pipe 16a directly connected to the outdoor heat exchanger 4, and the refrigerant is injected into the intermediate-pressure receiver 12 from the receiver charge port 15 provided in the refrigerant pipe 16b directly connected to the intermediate-pressure receiver 12. By injecting the refrigerant into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 constituting the outdoor unit 1 in this manner, an amount of refrigerant required in the refrigerant circuit can be reliably injected thereto in a well-balanced manner in accordance with the capacities of the outdoor heat exchanger 4 and the intermediate-pressure receiver 12. Therefore, because of absence of a liquid-sealed state being caused, the safety of the refrigerant injection process can be ensured, the reliability thereof can be improved, and a shorter refrigerant injection time can be achieved. Furthermore, by injecting the refrigerant simultaneously into the intermediate-pressure receiver 12 and the outdoor heat exchanger 4, the refrigerant injection time can be further shortened.
Accordingly, with the plurality of indoor units 8-1 to 8-n provided in Embodiment 2, an outdoor unit 1 is obtained that can comply with various configurations, so that an air-conditioning apparatus in which an amount of refrigerant required in the refrigerant circuit can be reliably and safely injected thereto within a short period of time at the outdoor-unit side, advantageously.

Embodiment 3

FIG. 8 is a schematic diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 3 of the present invention. In the drawing, reference numerals or characters that are the same as those in FIG. 1 denote the same or equivalent components. In Embodiment 3, a heat exchanging unit 24 where the refrigerant flowing through a refrigerant pipe 23 (this refrigerant pipe 23 will be referred to as “suction pipe”) connected to the suction side of the compressor 2 exchanges heat with the refrigerant retained in the intermediate-pressure receiver 12 serving as an excess-refrigerant container is provided. The heat exchanging unit 24 is configured such that the suction pipe 23 extends through the liquid refrigerant retained in the intermediate-pressure receiver 12. Although the refrigerant pipe in the heat exchanging unit 24 is indicated by a thick line in the drawing to provide an easier understanding of the heat exchanging unit 24, the refrigerant pipe may have a same or similar thickness or diameter as the other refrigerant pipes in an actual configuration.
A low-temperature low-pressure refrigerant in the suction pipe 23 is made to exchange heat with the excess refrigerant retained in the intermediate-pressure receiver 12 by the heat exchanging unit 24 so as to receive heat from the intermediate-temperature intermediate-pressure excess refrigerant retained in the intermediate-pressure receiver 12. Subsequently, the refrigerant is suctioned into the compressor 2. By receiving heat from the intermediate-temperature intermediate-pressure excess refrigerant, the

refrigerant at the suction side of the compressor 2 can be reliably turned into a gas state as indicated by
AA shown in a pressure-versus-specific-enthalpy diagram in FIG. 9. In other words, superheat (S) at the right side of a saturated vapor line can be ensured for the refrigerant to be suctioned into the compressor 2. If a refrigerant in a liquid state is suctioned into the compressor 2, the compressor 2 may possibly result in a failure, or the efficiency thereof may decrease. In the configuration according to Embodiment 3, since superheat (S) can be ensured so that the refrigerant can be reliably suctioned into the compressor 2 in a gas state, the reliability of the compressor 2 can be improved, and the load on the compressor 2 can be reduced, thereby improving the efficiency. The pressure-versus-specific-enthalpy diagram shown in FIG. 9 is a graph in which the abscissa axis denotes the specific enthalpy and the ordinate axis denotes the pressure. In the graph, D-DD and A-AA denote sections where the refrigerant retained in the intermediate-pressure receiver 12 and the refrigerant flowing through the suction pipe 23 exchange heat with each other at the heat exchanging unit 24 of the intermediate-pressure receiver 12.
In the refrigerant circuit having the intermediate-pressure receiver 12 and also having the heat exchanging unit 24 that exchanges heat between the refrigerant flowing through the suction pipe 23 and the excess refrigerant, as in this configuration, the outdoor-heat-exchanger charge port 14 and the receiver charge port 15 are provided so that the refrigerant can be injected into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12. Thus, the refrigerant can be injected in a well-balanced manner into the outdoor heat exchanger 4 and the intermediate-pressure receiver 12 that have large capacities among the devices contained in and constituting the outdoor unit 1, whereby an air-conditioning apparatus is obtained in which an amount of refrigerant required in the refrigerant circuit can be reliably and safely injected thereto within a short period of time.
In particular, in this configuration, the heat of the excess refrigerant in the intermediate-pressure receiver 12 can be effectively utilized.
According to Embodiment 3, the heat exchanging unit 24 that exchanges heat between the refrigerant flowing through the refrigerant pipe 23 connected to the suction side of the compressor 2 and the refrigerant retained in the excess-refrigerant container 12 is provided, so that the refrigerant to be suctioned into the compressor 2 is suctioned into the compressor 2 after exchanging heat with the refrigerant retained in the excess-refrigerant container 12 at the heat exchanging unit 24. Thus, the heat in the excess-refrigerant container 12 is effectively utilized so that a circuit configuration with improved reliability of the compressor 2 is achieved. In this circuit configuration, the outdoor-heat-exchanger refrigerant injection port 14 and the excess-refrigerant-container refrigerant injection port 15 are provided so that the refrigerant can be injected into the outdoor heat exchanger 4 and the excess-refrigerant container 12. Consequently, the refrigerant can be injected in a well-balanced manner into the outdoor heat exchanger 4 and the excess-refrigerant container 12 that have large capacities among the devices contained in and constituting the outdoor unit 1, whereby an air-conditioning apparatus is obtained in which an amount of refrigerant required in the refrigerant circuit can be reliably and safely injected thereto within a short period of time.
Although the heat exchanging unit 24 is configured such that the suction pipe 23 extends through the refrigerant retained in the intermediate-pressure receiver 12 in

FIG. 8, the configuration thereof is not limited to this. For example, the suction pipe 23 may be wound in close contact with the inner wall or the outer wall of the intermediate-pressure receiver 12. Any configuration is permissible so long as the refrigerant to be suctioned into the compressor 2 is suctioned into the compressor 2 after exchanging heat with the excess refrigerant retained in the intermediate-pressure receiver 12.Similar to Embodiment 1, in Embodiment 2 and Embodiment 3, the charge port 15 may be replaced with a charge port that is provided in the refrigerant pipe 16c directly connected to the intermediate-pressure receiver 12, or a charge port may be provided in each of the two refrigerant pipes 16b and 16c such that the refrigerant is injected into the intermediate-pressure receiver 12 from both charge ports.
Furthermore, the charge port 14 may be replaced with a charge port that is provided in the refrigerant pipe 16d

(see FIG. 4) directly connected to the outdoor heat exchanger 4, or a charge port may be provided in each of the two refrigerant pipes 16a and 16d such that the refrigerant is injected into the outdoor heat exchanger 4 from both charge ports. By injection of the refrigerant from a plurality of charge ports, the refrigerant injection time can be further shortened.

MITSUBISHI ELECTRIC PUHZ-ZRP100VKA POWER INVERTER Scroll compressor having step portions for reducing leakage of fluid:

A scroll compressor for reducing fluid leakage at step portions of scroll members and improving the compression efficiency is disclosed. The reduction of leakage and a high compression efficiency can be realized without increasing the precision in t

he manufacture of the members. Between the engaged scroll members, a high-pressure space is formed close to the spiral center, and among points at which the spiral walls contact with each other immediately before the innermost closed space communicates with the high-pressure space, the innermost point is defined as a base point. The angular distance from the base point to the outer end of the spiral, measured along the inner-peripheral face of the spiral wall, is approximately 4π rad. The angular distance from the base point to the step portion of each end plate, measured along the inner-peripheral face of the spiral wall, is equal to or more than approximately 3π rad.

1. A scroll compressor comprising: a fixed scroll member which has an end plate and a spiral wall provided on a face of this end plate and is fixed at a specific position; and a revolving scroll member which has an end plate and a spiral wall provided on a face of this end place and is supported in a manner such that the spiral walls are engaged with each other and the revolving scroll member can revolve, wherein: the face of the end plate of each scroll member, on which the spiral wall is provided, is divided into a plurality of areas which include a high portion closer to the center of the spiral, an adjacent low portion closer to the outer end of the spiral, and a step portion formed at the boundary of the high and low portions, wherein the high potion is higher than the low portion; the edge of each spiral wall has a low edge which corresponds to the high portion and is closer to the outer end of the spiral, a high edge which corresponds to the low portion and is closer to the outer end of the spiral, and a step portion formed at the boundary of the high and low edges; when the scroll members are engaged with each other, the end plates, the spiral walls, and the step portions partially contact each other, so that closed spaces are generated between the scroll memb

ers; the revolving scroll member is made to revolve so that the closed spaces gradually move from the outer end to the center of the spiral and the capacities of the closed spaces are gradually reduced and a fluid in the closed spaces is compressed; between the engaged scroll members, a high-pressure space which communicates with a discharge chamber is formed close to the center of the spiral, and among contact points at which the spiral walls of both scroll members contact with each other immediately before the innermost closed space communicates with the high-pressure space, the innermost contact point is defined as a base point; an angular distance from the base point to the outer end of each spiral wall, measured along the inner-peripheral face of the spiral wall, is approximately 4π rad; and an angular distance from the base point to the step portion of each end plate, measured along the inner-peripheral face of the corresponding spiral wall, is equal to or more than approximately 3π rad.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scroll compressor which is built into an air conditioner, refrigerating machine, or the like, and in particular, relates to the shape of scroll members therein.

2. Description of the Related Art

FIG. 8 is a cross-sectional view of a well-known scroll compressor. This scroll compressor comprises a fixed scroll member 101 which is fixedly attached to a housing 100 and a revolving scroll member 102 which is revolutionarily freely supported in the housing 100.
The fixed scroll member 101 has a fixed end plate 101a and a spiral wall 101b, and the revolving scroll member 102 has a revolving end plate 102a and a spiral wall 102b. The fixed and revolving scroll members 101 and 102 face each other in a manner such that the spiral walls 101b and 102b are engaged with each other with a phase difference of 180°, and the revolving scroll member 102 is made to revolve around the axis of the fixed scroll member 101 via the shaft 103, so that the capacities of compression chambers, which are formed between the spiral walls 101b and 102b, are gradually reduced and the fluid in the compression chambers is compressed, thereby finally discharging the high-pressure fluid from a discharge port 104 which is provided in a center portion of the fixed end plate 101a.
In this scroll compressor, the capacity of a crescent-shaped closed space formed at the outermost area of the spiral corresponds to the capacity for the introduced fluid which is gradually compressed. Therefore, in order to increase the capacity for the introduced fluid, that is, the capacity for the fluid to be compressed, the number of coils (or turns) of the spiral must be increased, or alternatively, the height of the spiral walls must be increased.
However, an increase in the number of turns of the spiral leads to an increase in the diameter of the compressor, and an increase in the height of the spiral walls causes a decrease in the rigidity of the spiral walls relative to the pressure of the compressed fluid.

Japanese Patent No. 1296413 (refer to Japanese Examined Patent Application, Second Publication No. Sho 60-17956) discloses an example structure for solving these problems.

FIGS. 6A and 6B are perspective views which respectively show a fixed scroll member 1 and a revolving scroll member 2 employed in this example. The fixed scroll member 1 has an end plate 1a and a spiral wall 1b which is formed on a face of the end plate 1a. Similarly, the revolving scroll member 2 has an end plate 2a and a spiral wall 2b which is formed on a face of the end plate 2a. In the above faces of the end plates 1a and 2a, step portions 3 and 3 are each formed, and in each step portion 3, the side closer to the center of the spiral is higher than the side closer to the outer end of the spiral. In addition, step portions 4 and 4 corresponding to the step portions 3 and 3 are each formed in the upper ends of the spiral walls 1b and 2b of the scroll members 1 and 2. In each step portion 4, the side closer to the center of the spiral is lower than the side closer to the outer end of the spiral.
Therefore, the above-explained scroll compressor has a feature that the spiral walls and end plates are respectively formed to have step portions, that is, in the spiral walls, the outer side (of the spiral) is higher and the center side is lower, while in the end plates, the outer side is lower and the center side is higher so as to correspond to the spiral walls.

FIG. 7 shows the engagement state in which the spiral walls 1b and 2b are engaged with each other with a phase difference of 180°. As shown in the figure, compression chambers C2 and C3 and the like are formed between the spiral walls 1b and 2b, by the end plates and/or the slide planes of the step portions of the end plates and spiral walls. In this state, when the revolving scroll member 2 revolves around the axis of the fixed scroll member 1, the capacities of the compression chambers gradually decrease, thereby compressing the relevant fluid.
In the above scroll compressor, the height of the compression chamber closer to the outer side of the spiral is relatively high; thus, the capacity for the introduced fluid can be increased without increasing the outer diameter of the compressor. In addition, the height of the compression chamber closer to the center can be low, so that high rigidity of the walls can be obtained.
However, in comparison with general scroll compressors having walls of a uniform height, each step portion 3 and the corresponding step portions 4 partially slide on each other, that is, the engagement of the step portions occurs. Therefore, even if a very slight gap between the engaged portions exists due to the working or assembling tolerance of the scroll members, the fluid may leak through the gap, and thus the compression efficiency is reduced.

In addition, in order to solve the above problem, the scroll members should be manufactured to a very high accuracy; thus, the productivity is very low and the manufacturing cost is very high.

SUMMARY OF THE INVENTION

In consideration of the above circumstances, the present invention relates to scroll compressors, which comprise scroll members having step portions, and an object of the present invention is to provide a scroll compressor for reducing leakage of the fluid occurring at the step portions as much as possible and improving the compression efficiency. Another object of the present invention is to provide a scroll compressor which has less leakage of the fluid and can realize a high compression efficiency without increasing the precision in the manufacture of the scroll members.
Therefore, the present invention provides a scroll compressor comprising:
a fixed scroll member which has an end plate and a

spiral wall provided on a face of this end plate and is fixed as a specific position; and
a revolving scroll member which has an end plate and a spiral wall provided on a face of this end plate and is supported in a manner such that the spiral walls are engaged with each other and the revolving scroll member can revolve while rotation is prohibited, wherein:
the face of each scroll member, on which the spiral wall is provided, is divided into a plurality of areas which include a high portion closer to the center of the spiral, an adjacent low portion closer to the outer end of the spiral, and a step portion formed at the boundary of the high and low portions, where the high portion is higher than the low portion;
the edge of each spiral wall has a low edge which corresponds to the high portion and is closer to the center of the spiral, a high edge which corresponds to the low portion and is closer to the outer end of the spiral, and a step portion formed at the boundary of the high and low edges;
when the scroll members are engaged with each other, the end plates, the spiral walls, and the step portions partially contact with each other, so that closed spaces are generated between the scroll members;
the revolving scroll member is made to revolve so that the closed spaces gradually move from the outer side to the center side of the spiral and the capacities of the closed spaces are gradually reduced and a fluid in the closed spaces is compressed;
between the engaged scroll members, a high-pressure space which communicates with a discharge chamber is formed close to the center of the spiral, and among contact points at which the spiral walls of both scroll members contact with each other immediately before the innermost closed space communicates with the high-pressure

space, the innermost contact point is defined as a base point;

the angular distance from the base point to the outer end of each spiral wall, measured along the inner-peripheral face of the spiral wall, is approximately 4π rad; and
the angular distance from the base point to the step portion of each end plate, measured along the inner-peripheral face of the corresponding spiral wall, is equal to or more than approximately 3π rad.
According to the above structure, each step portion can be placed in a preferable area of the scroll members. Therefore, it is possible that after the moment when the innermost closed space (called the first closed space) communicates with the high-pressure space (which communicates with the discharge chamber), the step portions do not participate in the formation of the first closed space. The high-pressure fluid reversely flows from the high-pressure space due to the communication of the first closed space with the high-pressure space, and the pressure of the fluid in the first closed space increases. Accordingly, even when the differential pressure between the first closed space and the second closed space (which is adjacent to the first closed space and is placed closer to the outer end of the spiral) increases, the step portions do not participate in the formation of the first closed space; thus, the leakage of the fluid due to the presence of the step portions can be avoided. That is, the step portions may participate in the formation of the second closed space or more distant closed spaces, thereby reducing the leakage of the fluid due to the presence of the step portions as much as possible and improving the compression efficiency. Such an improved compression efficiency can be realized without improving the precision in the manufacture of the scroll members.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a fixed scroll member as a constituent of the scroll compressor of an embodiment according to the present invention, which is viewed from a face on which a spiral wall is formed.
FIG. 2 is a view showing a revolving scroll member as another constituent of the scroll compressor of the embodiment, which is viewed from a face on which a spiral wall is formed.
FIG. 3 is a cross-sectional view showing a state in which the fixed and revolving scroll members of the scroll compressor are engaged with each other, which is viewed from a cross section perpendicular to the axis of the discharge port towards the fixed scroll member.
FIG. 4A is an enlarged view of area A in FIG. 3, while FIG. 4B is an enlarged view of area B in FIG. 3.
FIG. 5A is a graph showing changes in the pressure in each compression chamber versus the rotation angle of the revolving scroll member during the operation of the scroll compressor of the embodiment, and FIG. 5B is a graph showing changes in the pressure in each compression chamber along the rotation angle of the revolving scroll member during the operation of a conventional scroll compressor.
FIGS. 6A and 6B are perspective views which respectively show a fixed scroll member and a revolving scroll member employed in a conventional scroll compressor.
FIG. 7 is a cross-sectional view showing a state in which the fixed and revolving scroll members of the conventional scroll compressor are engaged with each other, which is viewed from a cross section perpendicular to the axis of the discharge port towards the fixed scroll member.
FIG. 8 is a cross-sectional view of the general structure of the conventional scroll compressor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the scroll compressor according to the present invention will be explained with reference to the drawings. The present invention is not limited to this embodiment. In addition, portions other than the scroll members have the same structures as those of the above-explained conventional scroll compressor; thus, detailed explanations thereof are omitted and the structure of the scroll members which are distinctive features of the present invention, in particular, the position where each step portion is formed, will be explained in detail below.

FIG. 1 is a view showing a fixed scroll member as a constituent of the scroll compressor of the present embodiment, which is viewed from a face on which a spiral wall is formed. FIG. 2 is a view showing a revolving scroll member as another constituent of the scroll compressor of the present embodiment, which is viewed from a face on which a spiral wall is formed. FIG. 3 is a cross-sectional view showing a state in which the fixed and revolving scroll members are engaged with each other, which is viewed from a cross section perpendicular to the axis of the discharge port towards the fixed scroll member. FIG. 4A is an enlarged view of area A in FIG. 3, while FIG. 4B is an enlarged view of area B in FIG. 3. FIG. 5A is a graph showing changes in the pressure in each compression chamber versus the rotation angle of the revolving scroll member dung the operation of the scroll compressor of the present embodiment. FIG. 5B is a graph showing changes in the pressure in each compression chamber along the rotation angle of the revolving scroll member during the operation of a conventional scroll compressor.
As shown in FIG. 1, a spiral wall 12b is formed on an end plate 12a of a fixed scroll member 12, and the face on which the spiral wall 12b is provided has a shallow bottom face 12f closer to the center of the spiral and a deep bottom farce 12g closer to the outer end of the spiral. A step portion 42 is formed at the boundary of the shallow portion 12f and the deep portion 12g, and a joint wall 12h stands vertically with respect to the axis of the fixed scroll member 12, between the bottom faces 12f and 12g.
Additionally, the edge of the spiral wall 12b has a lower edge 12c closer to the enter of the spiral and a higher edge 12d closer to the outer end of the spiral. Therefore, a step portion is also formed between the adjacent edges 12c and 12d and a joint edge 12e is formed between the edges 12c and 12d, which is vertically formed with respect to the axis of the fixed scroll member 12.

As shown in FIG. 2, a revolving scroll member 13 has an almost mirror-symmetrical shape with respect to the fixed scroll member 12. More specifically, an end plate 13a of the revolving scroll member 13 has a deep bottom face 13g and a shallow bottom face 13f are formed, which respectively correspond to the higher edge 12d and the lower edge 12c of the fixed scroll member 12, and a step portion 43 is formed between the deep bottom face 13g and the shallow bottom face 13f. A joint wall 13h, which stands vertically, is also formed at the boundary between the bottom faces 13f and 13g.
In addition, a spiral wall 13b of the revolving scroll member 13 has a higher edge 13d and a lower edge 13c which respectively correspond to the deep bottom fare 12g and the shallow bottom face 12f of the end plate 12a of the fixed scroll member 12, and at the boundary of the higher and lower edges 13c and 13d, a joint edge 13e is formed, which stands vertically with respect to the axis of the revolving scroll member 13.
When the revolving scroll member 13 is engaged with the fixed scroll member 12, the lower edge 13c contacts the shallow bottom face 12f and the higher edge 13d contacts the deep bottom face 12g. Simultaneously, the higher edge 12d contacts the deep bottom face 13g and the lower edge 12c contacts the shallow bottom face 13f.

Accordingly, as shown in FIG. 3, the space between the fixed and revolving scroll members 12 and 13 is divided into a plurality of compression chambers by the end plates 12a and 13a (which face each other) and the spiral walls 12b and 13b. According to the revolution of the revolving scroll member 13, the capacities of these compression chambers are gradually reduced while the compression chambers gradually move from the outer side to the center side of the spiral, thereby compressing the fluid, and finally, the high-pressure fluid is discharged from a discharge port 25 which is provided in a center area of the end plate 12a of the fixed scroll member 12.
Below, the positions of the step portions 42 and 43 (which are distinctive features of the present invention) will be explained. In the fixed scroll member 12 and the revolving scroll member 13, the spiral walls 12b and 13b have symmetrical forms with each other, and the end plates 12a and 13a also have symmetrical forms. Therefore, the structure of the fixed scroll member 12 will be explained in detail, and a detailed explanation of the structure of the revolving scroll member 13 (i.e., the position of the step portion 43) is omitted.

FIG. 3 shows a state in which the fixed scroll member 12 and the revolving scroll member 13 are engaged with each other. Between the spiral walls 12b and 13b, a high-pressure chamber C1 which communicates with the discharge port 25 of the fixed scroll member 12, and two crescent-shaped compression chambers C2 and C3 (corresponding to the closed spaces of the present invention) are formed, where the compression chambers C2 and C3 are each adjacent to the high-pressure chamber C1. FIG. 3 shows a specific state immediately before the compression chamber C2 is communicated with the high-pressure chamber C1. In the following explanations, this state will be called the “engagement state immediately before communication with the high-pressure space”. In this state, a sealed position between the high-pressure chamber C1 and the compression chamber (i.e., closed space) C2, that is, a sealed point between spiral walls 12b and 13b, is defined as a base point P1.
In the scroll members of the present embodiment, the spiral end 13i of the spiral wall 13b is away from the base point P1 by an angular distance of 4π rad measured along the inner-peripheral face of the spiral wall 13b. Therefore, the number of coils (or turns) of the spiral is relatively small. In addition, P2 is a position away from the base point P1 by an angular distance of 3π rad measured along the inner-peripheral face of the spiral wall 12b, and the angular distance between the base point PI and the step portion 42 is 3π rad or more, that is, the step portion 42 is positioned at P2 or a more distant point.
As explained above, the base point P1 is defined based on the state immediately before the compression chamber C2 communicates with the discharge port 25 (i.e., high-pressure chamber C1) at point P3 (see FIG. 4A). Therefore, if the revolving scroll member 13 further revolves very slightly, this communication occurs. Under this “engagement state immediately before communication with the high-pressure space”, the inner-peripheral face 12x of an end portion 12E at the center side of the spiral wall 12b and the outer-peripheral face 13x of an end portion 13E at the center side of the spiral wall 13b make linear contact at the base point P1

(i.e., “point contact” in the observation direction of FIG. 4A). This base point P1 is a starting point for measuring the angular distance and defining the above position P2; thus, the position of the base point P1 is defined as 0 rad.
When a spiral figure is drawn from the base point P1 along the inner-peripheral face 12x towards the outer end of the spiral wall 12b (see FIG. 4B), the line between the base curve for drawing an involute which corresponds to the spiral figure and the base point P1 on the involute is defined as 0 rad. The angular distance from the base point P1 to the position P2 is 3π rad. In the spiral wall 12b, the contact position x between the step portion 42 and the inner-peripheral face 12x is placed at P2 or a position closer to the outer end of the spiral. In FIG. 4, the step portion 42 is placed at the innermost position under this condition, that is, the position P2 overlaps with the contact position x.

In FIG. 4B, reference character 12y indicates the outer peripheral face of the inner wall adjacent to the wall including the point P2, and reference characters C3 and C4 indicate adjacent compression chambers. The contact position y between the step portion 42 and the outer-peripheral face 12y is placed on the line between the above base curve (for the involute) and the contact position x. The step portion 42 has a semicircle form which has two end points corresponding to the contact positions x and y. Here, the contact position y does not overlap with the compression chamber C3 and thus no portion of the step portion 42 is present in the area of th

e compression chamber C3 under the above-explained engagement state immediately before communication with the high-pressure space.

FIGS. 5A and 5B are diagrams for explaining the effects obtained by the scroll compressor having the above-explained structure. FIG. 5A shows a correlation between the pressure of each compression chamber and the rotation angle of the crank shaft in the present invention, while FIG. 5B shows a correlation between the pressure of each compression chamber and the rotation angle of the crank shaft in a structure in which the step portions 42 and 43 are shifted to the center side of the spiral (i.e., corresponding to the conventional example as shown in FIG. 7). In the operation conditions of the compressor which were employed, the defined low pressure is 0.4 Mpa while the defined high pressure is 25 Mpa.
The rate of change of the capacity of the compression chamber depends on the positions of the step portions 42 and 43; thus, even with the same rotation angle of the crank shaft, the rising point P of the pressure of the compression chamber changes according to the positions of the step portions 42 and 43. In FIG. 5A, the line indicated by reference numeral 200 (i.e., solid line) shows the variation of the pressure when the step portions 42 and 43 according to the present invention are formed. If the positions of these step portions 42 and 43 are shifted along the spiral towards the center side so as to have the structure shown in the conventional example (refer to FIG. 7), the variation of the pressure is shown by the line 201 (i.e., solid line) in FIG. 5B.

Each point P in FIGS. 5A and 5B corresponds to the above-explained engagement state immediately before communication with the high-pressure space. In the pressure range higher than P (i.e., the right side of P in each figure), the compression chamber communicates with the high-pressure chamber C1, and accordingly, the high-pressure fluid remaining in the high-pressure chamber C1 reversely flows into the compression chamber. As a result, the pressure of the compression chamber increases suddenly, that is, the pressure of the compression chamber suddenly increases immediately after the point P.
The line indicated by reference numeral 300 (i.e., dotted line) shows a variation of the adjacent compression chamber which is closer to the outer side of the spiral (i.e., adjacent to the compression chamber having the variation of pressure indicated by reference numeral 200) in the scroll compressor of the present embodiment. Similarly, the line indicated by reference numeral 301 (i.e., dotted line) shows a variation of the adjacent compression chamber which is closer to the outer side of the spiral (i.e., adjacent to the compression chamber having the variation of pressure indicated by reference numeral 201) in the scroll compressor of the conventional example.
With reference to FIGS. 5

A and 5B, the distinctive features of the present embodiment in comparison with the conventional example will be explained. In the conventional scroll compressor shown by FIG. 5B, the range in which the engaged portions at the step portions 42 and 43 (corresponding to the step portions 3, 3 in FIG. 7) participate in the formation of the compression chambers is L1, which corresponds to a rotation angle of the crank shaft of 180 degrees. Conversely, in the scroll compressor according to the present invention shown by FIG. 5A, the range in which the engaged portions at the step portions 42 and 43 participate in the formation of the compression chambers is L0, which corresponds to a rotation angle of the crank shaft of 180 degrees.
Each engaged portion at the step portions 42 and 43 has a minute gap due to a tolerance for the mechanical processing or assembly. The leakage of fluid through the gap corresponds to the differential pressure of the fluid within the range where the engaged portions at the step portions 42 and 43 participate in the formation of the compression chambers, that is, (i) differential pressure ΔP1 between the lines 201 and 301 in the conventional example and (ii) differential pressure ΔP0 between the lines 200 and 300 in the present embodiment within that range. With reference to FIGS. 5A and 5B, it is obvious that ΔP1>ΔP0. Accordingly, in the present embodiment, it is possible to reduce the leakage of fluid through a gap of the engaged portions at the step portions 42 and 43 (which are provided in the scroll members), thereby improving the compression efficiency.

That is, in the scroll compressor having the step portions 42 and 43 of the present embodiment, the step portion 42 is placed at the position P2 or a position closer to the outer end of the spiral, where the angular distance from the base point P1 to the position P2 (measured along the inner-peripheral face of the spiral wall 12b) is 3π rad, and similarly, the step portion 43 is placed at the corresponding position (3π rad) or a more distant position. According to this structure, as shown in FIG. 5A, the engaged portions at the step portions 42 and 43 do not relate to the formation of the compression chambers in the pressure range higher than the point P, where the pressure of the compression chamber is very high. Therefore, the leakage of fluid through a gap at the step portions 42 and 43 can be reduced as much as possible, thereby improving the compression efficiency.
In the present embodiment, the angular distance from the base point P1 to the spiral end 13i measured along the inner-peripheral face of the spiral wall 13b is 4π rad. However, practically, this angular distance may be selected from 3.3π rad to 5π rad so as to obtain similar effects of the present invention. In addition, similar variations can be applied to the spiral wall 12b.
Also in the present embodiment, the angular distance from the base point P1 to the step portion 42 measured along the inner-peripheral face of the spiral wall 12b is 3π rad or more. However, if this angular distance is slightly smaller than 3π rad (e.g., 2.7π rad, that is, 0.3π rad closer to the center of the spiral), the corresponding reduction of the compression efficiency is small and effects similar to those of the present invention can also be obtained. In addition, similar variations can be applied to the step portion 43