JPH09145169A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormally high pressure from being generated in a refrigerating circuit with a simple construction and prevent an operation capacity from being lowered. SOLUTION: According to an air conditioner, when a pressure sensor 2a detects the prescribed high pressure of the discharging side of a compressor in a refrigerating circuit using a mixed refrigerant as a refrigerant, a pressure reducing valve 2c for controlling to open and close a bypass circuit 2b which connects the discharge side of the compressor to a suction side is opened, so that the refrigerant of the discharge side of the compressor is returned to the suction side. Thus, the discharge pressure of the compressor in the refrigerating circuit is reduced and the generation of the abnormally high pressure can be prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a compressor, a condenser,
The present invention relates to an air conditioner having a refrigerant circuit having a decompression device, an evaporator, and the like, and particularly to an air conditioner using a mixed refrigerant in which two kinds of refrigerants having different characteristics are mixed.

[0002]

2. Description of the Related Art Generally, a refrigerant circuit of an air conditioner is constructed by connecting a compressor, a four-way switching valve, a condenser, a pressure reducer and an evaporator with a refrigerant pipe, and circulating a refrigerant in the refrigerant circuit. There is.

Since the refrigerant circuit compresses and discharges the refrigerant and circulates the refrigerant circuit, a predetermined refrigerant pressure is generated in the refrigerant circuit, but it is designed to be sufficiently safe to withstand the predetermined pressure. However, as in the case where the outside air temperature rises unexpectedly, the pressure in the refrigerant circuit may abnormally rise above the assumed pressure due to the influence of the external environment and the like. When the refrigerant pressure in the refrigerant circuit becomes abnormally high as described above, the refrigerant circuit may be damaged, so the pressure relief valve provided in the refrigerant circuit is opened to release the pressure, and the refrigerant circuit It prevents the abnormal increase of pressure inside.

On the other hand, as the refrigerant filled in the refrigerant circuit,
Conventionally, R-12 or having a chlorine group was used, but since it has the potential of depleting the ozone layer above the ground, R-22 (chlorodifluoromethane) or a low content of chlorine group is used for the purpose of environmental protection. , Chlorine-free R-32 (difluoromethane), R-125 (pentafluoroethane), R
-134a (tetrafluoroethane) or a mixture thereof (hereinafter referred to as "HFC-based refrigerant") is used as an alternative refrigerant.

When such an HFC type refrigerant is used as the refrigerant, the operating pressure is higher than that of the conventional single refrigerant (for example, R-22) due to the nature of the mixed refrigerant, so that the refrigerant circuit is abnormal. It is easy to generate high pressure.

[0006]

When an HFC type refrigerant having a high pressure during operation is used as a refrigerant, if the conventional refrigerant circuit (refrigerant pipe, refrigerant device, etc.) is used as it is, the refrigerant circuit The pressure relief valve described above is required to prevent damage.

However, if the pressure relief valve is opened during operation, the operating capacity of the air conditioner is interrupted, and the pressure relief valve is often opened, especially when a mixed refrigerant having a high pressure during operation is used. This is not preferable because the operation is frequently interrupted.

It is also possible to review the pressure resistance of the refrigerant circuit. However, reviewing the pressure resistance requires changing the strength setting of the components such as the refrigerant pipe and the refrigerant equipment, and the thickness of the refrigerant pipe becomes thick. There are problems such as an increase in weight and an increase in size.

The present invention has been made in order to solve the above problems, and provides an air conditioner capable of preventing an abnormally high pressure from being generated in a refrigerant circuit with a simple structure and at the same time preventing a decrease in operating capacity. It is provided.

[0010]

According to a first aspect of the present invention, in a refrigerant circuit having a compressor, a condenser, a pressure reducer, and an evaporator, a mixed refrigerant in which at least two kinds of refrigerants having different characteristics are mixed. In an air conditioner configured to be circulated in the air conditioner, a pressure detection unit that is provided on the discharge side of the compressor and detects the refrigerant pressure, and a bypass circuit that connects between the discharge side and the suction side of the compressor. A pressure reducing valve that opens and closes the bypass circuit, and a control device that controls the opening degree of the pressure reducing valve based on the pressure detected by the pressure detecting means.

According to the invention described in claim 1, when the discharge side pressure of the compressor is higher than a predetermined pressure, the control device opens the pressure reducing valve of the bypass circuit and discharges from the compressor. A part of the refrigerant is released to the suction side to relatively reduce the discharge pressure of the compressor. This prevents the occurrence of abnormally high pressure in the refrigerant circuit, and in particular, even when a mixed refrigerant is used as the refrigerant, the conventional pressure-resistant designed refrigerant circuit can be used. In addition, since continuous operation can be performed without interruption of operation, it is possible to prevent the air conditioner from significantly deteriorating its performance.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressure reducing valve is a multi-stage throttle valve or expansion valve whose opening degree is variable in a plurality of stages, and the control device. Is for opening the pressure reducing valve at a predetermined opening based on the pressure detected by the pressure detecting means.

According to the second aspect of the present invention, since the pressure reducing valve can be set to a predetermined opening according to the detected pressure, the degree of pressure reduction at high pressure can be minimized. As a result, it is possible to maintain the inside of the refrigerant circuit at a predetermined pressure while minimizing the decrease in the operating capacity of the air conditioner.

According to a third aspect of the present invention, a mixed refrigerant in which at least two kinds of refrigerants having different characteristics are mixed is circulated in a refrigerant circuit having a compressor, a condenser, a pressure reducer and an evaporator. In the air conditioner, a bypass circuit connecting the discharge side and the suction side of the compressor, and a pressure valve provided in the bypass circuit and opened in response to the pressure on the discharge side are provided. Is.

According to the third aspect of the invention, when the pressure on the discharge side increases, the valve opens in response to the increased pressure without the need for the pressure detecting means for detecting the pressure of the refrigerant,
Since the refrigerant on the discharge side of the compressor is released to the suction side, the pressure in the refrigerant circuit can be prevented from increasing with a simpler structure.

[0016]

Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a general household air conditioner. This type of air conditioner is composed of a use side unit A arranged indoors and a heat source side unit B arranged outdoors, both of which are connected by a refrigerant pipe 300.

FIG. 2 is a refrigerant circuit diagram showing a refrigeration cycle of the air conditioner shown in FIG.

Reference numeral 1 denotes a compressor which comprises a motor section and a compression section driven by the motor section. In this embodiment, the high pressure of the refrigerant circuit is dealt with by returning the discharged refrigerant from the bypass circuit as described later.

Although not shown, a muffler is provided to suppress vibration and noise due to the pulsation of the refrigerant discharged from the compressor 1.

Reference numeral 3 is a four-way switching valve for switching the flow of refrigerant during cooling / heating operation. 4 is a heat source side heat exchanger,
Reference numeral 5 is a capillary tube, 6 is a screen filter, 7 is a use side heat exchanger, 8 is a muffler, and 9 is an accumulator.

Here, a bypass structure for bypassing the refrigerant on the discharge side of the compressor to the suction side of the compressor in order to prevent the refrigerant circuit from becoming abnormally high in pressure will be described.

Reference numeral 2a is a pressure sensor as pressure detecting means for detecting the refrigerant pressure on the discharge side of the compressor 1. Also,
Reference numeral 2b is a bypass circuit that connects between the discharge side of the compressor 1 and the suction side accumulator 9, and 10 is an electromagnetic on-off valve. Further, the pressure sensor 2 is provided in the bypass circuit 2b.
The bypass circuit 2 based on the refrigerant pressure detected in a.
Similar to the pressure reducing valve for controlling the opening / closing of b, for example, the electromagnetic opening / closing valve 10, a throttle valve 2c that is switched in multiple stages by current control is provided. The pressure sensor 2a and the throttle valve 2c are connected to the control device 41, and the opening degree of the throttle valve 2a is controlled based on the detection signal of the pressure sensor 2a.

With such a configuration of the refrigerant circuit, the refrigerant discharged from the compressor 1 is indicated by a solid arrow (cooling operation) and a dotted line according to the switching position of the four-way switching valve 3 and the opening / closing of the electromagnetic opening / closing valve 10. The direction of flow is determined according to the three modes, as indicated by the arrow (heating operation) and the arrow at the midpoint of the solid line (defrosting operation).

During the cooling operation, the heat source side heat exchanger 4 functions as a condenser and the use side heat exchanger 7 functions as an evaporator.
Further, during the heating operation, the use side heat exchanger 7 functions as a condenser and the heat source side heat exchanger 4 functions as an evaporator. During the defrosting operation (during the heating operation), a part of the high-temperature refrigerant discharged from the compressor 1 is directly supplied to the heat source side heat exchanger 4 in order to raise the temperature of the heat source side heat exchanger 4. Is done. As a result, the temperature of the heat source side heat exchanger 4 rises and defrosting is performed.
When the defrosting operation does not function sufficiently (especially when the outside air temperature is low), defrosting is forcibly performed by reverse cycle defrosting (flow indicated by a solid arrow).

FIG. 3 is a control circuit diagram of the air conditioner.
The left side shows the control circuit of the utilization side unit A, and the right side shows the control circuit of the heat source side unit B with the dashed line in the center of FIG. 3 as the boundary. Both control circuits have power line 10
0 and the control line 200.

The user side unit A includes a rectifying circuit 11 and
A power supply circuit 12 for the motor, a power supply circuit 13 for the control, a motor drive circuit 15, a switch board 17,
The receiving circuit 18a, the display board 18, and the flap motor 1
9 and 9 are provided.

The rectifier circuit 11 rectifies the 100V AC voltage supplied by the plug 10a. The motor power supply circuit 12 adjusts the DC voltage supplied to the DC fan motor 16 to a voltage of 10 to 36V. The DC fan motor 16 is for blowing out conditioned air into the room to be conditioned according to a signal sent from the microcomputer 14.

The control power supply circuit 13 generates a 5V DC voltage supplied to the microcomputer 14. The motor drive circuit 15 includes a microcomputer 14
In response to the signal from, the rotation speed is controlled by controlling the energization timing to the stator winding based on the rotation position information of the DC fan motor 16. The switch board 17 is fixed to the operation panel of the utilization side unit A, and the switch board 17 is provided with an on / off switch, a trial run switch, and the like. The receiving circuit 18a receives a remote operation signal (for example, an on / off signal, a cooling / heating switching signal, a room temperature setting signal, or the like) from the wireless remote controller 60. The display board 18 displays the operating state of the air conditioner. The flap motor 19 functions to move a flap that changes the blowing direction of cold / warm air.

Further, the control circuit includes a room temperature sensor 20 for measuring the room temperature, a heat exchanger temperature sensor 21 for measuring the temperature of the utilization side heat exchanger, and a room humidity sensor. A humidity sensor 22 is provided. The measured values detected by these sensors are A / D converted and taken into the microcomputer 14. The control signal from the microcomputer 14 is sent to the heat source side unit B through the serial circuit 23 and the terminal board T3. Further, the triac 26 and the heater relay 27 are controlled by the microcomputer 14 through the driver 24, thereby stepwise controlling the electric power supplied to the reheat heater 25 used during the dry operation.

Reference numeral 30 is an external ROM that stores specific data indicating the type and characteristics of the air conditioner. These specific data are taken out from the external ROM immediately after the power switch is input and the operation is stopped. When the power switch is input, commands are input from the wireless remote controller 60 or ON / OFF until the extraction of specific data from the external ROM 30 is completed.
The state of the switch or the trial run switch (operation will be described later) is not detected.

Next, the control circuit of the heat source side unit B will be described.

In the heat source side unit B, the terminal board T'1
, T'2, T'3 are respectively connected to terminal plates T1, T2, T3 arranged in the use side unit A. Reference numeral 31 is a varistor connected in parallel to the terminal plates T'1 and T'2, 32 is a noise filter, 34 is a reactor, 35 is a voltage doubler rectifier that doubles the voltage, and 36 is a noise filter.

Reference numeral 39 is a serial circuit for converting the control signal supplied from the user side unit A through the terminal board T'3, and the converted signal is transmitted to the microcomputer 41. 40 is the heat source side unit B
And a current detector that detects the current supplied to the load in the current transformer (CT) 33, rectifies the current into a DC voltage, and applies the DC voltage to the microcomputer 41.
Reference numeral 41 is a microcomputer, and 42 is a switching power supply circuit for generating power for operating the microcomputer 41.

Reference numeral 43 designates the compressor 1 of the refrigeration cycle.
And 44 is a discharge side temperature sensor for detecting the temperature of the refrigerant on the discharge side of the compressor. Reference numeral 45 is a fan motor whose speed is controlled in three stages and sends air to the outdoor heat exchanger, and the four-way switching valve 3 and the electromagnetic valve 10 switch the refrigerant passage of the refrigeration cycle as described above. Further, the heat source side unit B has an outdoor temperature sensor 48 for detecting the outdoor temperature.
However, the outdoor heat exchanger temperature sensor 49 for detecting the temperature of the outdoor heat exchanger is disposed in the vicinity of the air intake port. Further, a pressure sensor 2a for detecting the refrigerant pressure
Are arranged on the discharge side of the compressor 1. The detected values obtained by the temperature sensors 48 and 49 and the pressure sensor 2a are A / D converted and are taken into the microcomputer 41. Then, based on the control signal from the microcomputer 41, the throttle valve 2c operates as the bypass circuit 2
Switching control is performed so that a is controlled to be opened and closed to reduce the refrigerant pressure in the refrigerant circuit.

Reference numeral 50 is an external ROM of the user side unit A.
It is an external ROM having the same function as 30. The specific data of the heat source side unit B is the same as that described for the external ROM 30, but is stored in the ROM 50.

The symbol F in each control circuit of the heat source side unit B and the use side unit A is a fuse.

Each of the microcomputers (control circuits) 14 and 41 is a ROM that stores a program in advance,
A RAM that stores reference data and a CPU that calculates a program are stored in the same container (87C196MC (MC sold by Intel Corporation).
S-96 series)).

Next, the refrigerant will be described.

The present embodiment is suitable for a refrigerant having a high pressure during operation, and either single refrigerant or mixed refrigerant can be used. For example, R-41
0A and R-410B are used. R-410A is 2
It is a mixed refrigerant of a component system and has a composition of R-32 of 50 wt% and R-125 of 50 wt% and a boiling point of -52.2.
C, dew point is -52.2C. The R-410B has a composition of 45 Wt% for R-32 and 55 Wt% for R-125.

In such a two-component mixed refrigerant, HCFC
When compared with the conventional single refrigerant of No. 22, the discharge temperature of the compressor is 66.0 ° C for HCFC-22 and 73.6 ° C for R-410A under the specified conditions, and the condensing pressure is HCFC- 22 has 17.35 bar, while R-410A has 27.30 bar, and the vapor pressure is 6.79 bar with HCFC-22, while R-410A has the characteristic of 10.86 bar, As a whole refrigerant circuit, conventional HCFC-2
The temperature and pressure are higher than when using a single refrigerant of 2.

On the other hand, when a mixed refrigerant such as R-410A and R-410B is used, since the boiling points of the refrigerants of the respective components are close to each other, it is difficult for the refrigerant composition to change, and the refrigerant composition changes. There is no need to consider the problems such as temperature glide that occur. Therefore, control during driving becomes easy.

Next, the operation of this embodiment will be described.

During the cooling operation, as shown by the solid arrow in FIG. 2, the refrigerant discharged from the compressor 1 includes a muffler 2, a four-way switching valve 3, a heat source side heat exchanger (outdoor heat exchanger) 4, a pressure reducer. The capillary tube 5, the screen filter 6, the use side heat exchanger (outdoor heat exchanger) 7, the muffler 8, the four-way switching valve 3, and the accumulator 9 circulate through the refrigerant circuit in this order, and the use side heat exchanger 7 evaporates. Function as a container,
The pressure is reduced in the capillary tube 5. During heating operation,
As shown by the broken line arrow, the refrigerant discharged from the compressor 1 includes a muffler 2, a four-way switching valve 3, a muffler 8, a use side heat exchanger (outdoor heat exchanger) 7, a screen filter 6,
The capillary tube 5, the heat source side heat exchanger (outdoor heat exchanger) 4, the four-way switching valve 3, and the accumulator 9 circulate through the refrigerant circuit in this order, and the heat source side heat exchanger 4 functions as an evaporator. The pressure is reduced.

In the present embodiment, as described above, since R-410A and R-410B, which are two-component mixed refrigerants, are used as the refrigerants, as compared with the case where a single refrigerant is used,
The refrigerant pressure in the refrigerant pipe during operation is high. For this reason,
Conventionally, the pressure relief valve is appropriately opened to keep the pressure in the refrigerant circuit below a specified value. Therefore, in the embodiment of the present invention, the conventional pressure relief valve is not used, and the refrigerant on the discharge side of the compressor is returned to the suction side to prevent the occurrence of abnormally high pressure in the refrigerant circuit.

The control operation for preventing the high pressure generation in the refrigerant circuit will be described below with reference to FIG.

In step S1, the pressure sensor 2a detects the discharge pressure of the compressor and sends the detection signal to the control device 41. The pressure sensor 2a may detect the pressure every predetermined time, or may emit a detection signal when a certain pressure value is exceeded. In the present embodiment, the pulsation of the compressor is taken into consideration, and 0.
A pressure signal is issued to the control device 41 every 1 microsecond.

In the case where the microcomputer is not used, it is desirable that the control device 41 be configured to issue a pressure signal which is a value obtained by rectifying a value obtained by rectifying a voltage obtained by averaging the voltage based on the pressure detected by the pressure sensor.

In step S2, the control device 41 calculates the deviation from the reference pressure value based on the detection signal from the pressure sensor 2a. This deviation is obtained by calculating an average value every 30 seconds, for example.

In step S3, the opening of the throttle valve 2c is determined based on the deviation calculated in step S2. The opening degree of the throttle valve 2c can be set in multiple stages, and in the present embodiment, it is controlled in 0 to 256 stages.

In this case, it is desirable to set a plurality of target values and control the opening of the throttle valve 2c according to each target value.

For example, when the target pressure value A is set and reaches the target pressure value A, the pressure is detected every 30 seconds, and the throttle valve 2c is opened in 10 steps in accordance with the detected pressure value. When the detected pressure value B is higher than the target pressure value A, the pressure is detected every 2 or 3 seconds, and the opening is controlled step by step according to the detected pressure value. If control is performed to set such a plurality of target values, a sudden change in pressure does not occur, and stable operation can be performed.

As the target pressure value, the pressure resistance safety of the refrigerant circuit varies depending on the type of the air conditioner. Generally, when the pressure target value is 25 to 30 kg / cm 2, for example,
The target pressure value A is set to 20 Kg / cm2 and the target pressure value B is set to 2
5 kg / cm2.

In step S4, the throttle valve 2c is opened to a predetermined opening based on the opening command from the control device 41.

As a result, as shown in FIG. 2, the high-pressure refrigerant on the discharge side of the compressor 1 is released to the low-pressure side on the suction side of the compressor through the bypass circuit 2b, and the compressor 1 is relatively moved. The discharge pressure of is reduced, and generation of high pressure in the refrigerant circuit can be prevented. Further, by controlling the throttle valve 2c to have a multi-step opening corresponding to a plurality of upper limit pressure values, the pressure relief amount is minimized to achieve stable operation, and the capacity during cooling / heating operation is further enhanced. You can

In this embodiment, as described above, by providing the bypass circuit 2c, it is possible to prevent the abnormal high pressure from being generated in the refrigerant circuit, and in particular, even when the mixed refrigerant is used as the refrigerant, the conventional pressure resistance design is performed. The refrigerant circuit can be used. Also, without interrupting the operation of the air conditioner,
Can be operated continuously.

Next, another embodiment of the present invention will be described.

In the second embodiment of the present invention, as shown in FIG. 5, the bypass circuit 2b includes a multi-stage throttle valve 2 as described above.
An on-off valve 2e that only opens and closes is provided instead of c, and a capillary tube 2f that gives resistance to the low-pressure side is arranged, and the other parts have the same configuration as the above-described embodiment shown in FIG. I have.

In the second embodiment, the pressure sensor 2
When a detects a high pressure, even if the on-off valve 2e is opened and the high-pressure refrigerant is returned to the suction side of the compressor 1, the operation of the refrigerant circuit of the refrigerant circuit can be performed without interruption as in the above-described embodiment. It can prevent the generation of abnormal high pressure.

In the third embodiment of the present invention, without using the pressure sensor 2a, the valve opens and closes in response to the refrigerant pressure,
The configuration is such that the high pressure refrigerant is released to the low pressure side. That is, FIG.
As shown in FIG. 2, the bypass circuit 2b is provided with a pressure expansion valve 2g that opens and closes in response to the received pressure, and a capillary tube 2f that imparts a predetermined resistance to prevent the low-pressure side refrigerant from returning. 2 and the other parts have the same configuration as the above-described embodiment shown in FIG.
In the case of this embodiment, since no pressure sensor or control device is required, the mechanism for preventing the generation of high pressure can have a simple structure. Further, it is easy to set the response pressure of the pressure expansion valve 2b for each model.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, the pressure sensor 2a is not limited to being arranged in the vicinity of the discharge port of the compressor 1, but the same effect can be obtained if it is on the high pressure side of the refrigerant circuit.

Even if a temperature sensor is used instead of the pressure sensor 2a and the opening degree of the opening / closing valve is controlled based on the detected temperature, the same effect can be obtained. In this case, since the relationship between the pressure and the temperature varies depending on the characteristics of the refrigerant, it is desirable to find the relationship between the temperature and the pressure based on the experimental data conducted in advance. Furthermore, instead of the pressure expansion valve that opens and closes in response to the pressure used in the third embodiment, a thermal expansion valve that operates in response to heat can be used.

Further, in the above-described first to third embodiments, the bypass circuit may be constructed so as to be built in the compressor 1, and the refrigerant escapes from the high pressure side to the low pressure side of the refrigerant circuit. It suffices as long as the discharge port of the compressor 1 and the suction port of the compressor 1 are bypassed.

If a pressure reducing valve whose opening is changed by current control is used as the pressure reducing valve, abnormal high pressure in the refrigerant circuit can be prevented while performing continuous and smooth operation.

[0066]

According to the first aspect of the present invention, in the air conditioner configured to circulate the mixed refrigerant in the refrigerant circuit, the pressure reduction in the bypass circuit is performed based on the refrigerant pressure detected by the pressure detection means. Since the valve opening is controlled, it is possible to prevent a part of the refrigerant discharged from the compressor from being discharged to the suction side when the refrigerant pressure becomes high, thereby preventing abnormal high pressure in the refrigerant circuit. Further, a conventional pressure-resistant designed refrigerant circuit can be used, and continuous operation can be continued without interruption of operation, which can prevent a significant decrease in capacity of the air conditioner.

According to the invention described in claim 2, according to claim 1
In addition to the invention described in (1), since the pressure reducing valve can be set to a predetermined opening according to the detected pressure, the pressure reducing amount at the time of high pressure can be minimized. As a result, it is possible to maintain the inside of the refrigerant circuit at a predetermined pressure while minimizing the decrease in the operating capacity of the air conditioner.

According to the third aspect of the invention, the pressure detecting means for detecting the pressure of the refrigerant is not required, and when the pressure on the discharge side becomes high, the valve opens in response to the increased pressure and the compression is performed. Since the refrigerant on the discharge side of the machine is made to escape to the suction side, the pressure increase in the refrigerant circuit can be prevented with a simpler structure.

[0069]

[Brief description of the drawings]

FIG. 1 is a perspective view of an air conditioner applied to an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of the air conditioner shown in FIG.

FIG. 3 is a control circuit diagram of the air conditioner shown in FIG. 1.

4 is a flowchart showing a control operation of the refrigerant circuit of FIG.

FIG. 5 is a circuit diagram showing a main part of a refrigerant circuit according to another embodiment.

FIG. 6 is a circuit diagram showing a main part of a refrigerant circuit according to another embodiment.

[Explanation of symbols]

 1 Compressor 2a Pressure sensor 2b Bypass circuit 2c Throttle valve (pressure reducing valve) 2e Open / close valve (pressure reducing valve) 2g Pressure expansion valve (pressure valve) 41 Control device

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Koizumi Friend 2-5-5 Keihan Hon-dori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Mikiyasu Mitsuyasu 2-chome, Keihan-hondori, Moriguchi No. 5 within Sanyo Electric Co., Ltd. (72) Inventor Shigeya Ishigaki 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Within Sanyo Electric Co., Ltd. (72) Norio Akutagawa, 2 Keihan Hondori, Moriguchi City, Osaka Prefecture 5-5, Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. An air conditioner configured to circulate a mixed refrigerant, in which at least two kinds of refrigerants having different characteristics are mixed, in a refrigerant circuit having a compressor, a condenser, a pressure reducer, and an evaporator, A pressure detection unit provided on the discharge side of the compressor for detecting the refrigerant pressure, a bypass circuit connecting the discharge side and the suction side of the compressor, a pressure reducing valve for opening and closing the bypass circuit, and the pressure An air conditioner comprising: a control device that controls the opening of the pressure reducing valve based on the pressure detected by the detection means. 2. The pressure reducing valve is a multi-stage throttle valve or expansion valve whose opening is variable in a plurality of stages, and the control device controls the pressure reducing valve based on the pressure detected by the pressure detecting means. The air conditioner according to claim 1, wherein the air conditioner opens at a predetermined opening. 3. An air conditioner configured to circulate a mixed refrigerant, in which at least two kinds of refrigerants having different characteristics are mixed, in a refrigerant circuit having a compressor, a condenser, a pressure reducer, and an evaporator. An air conditioner comprising: a bypass circuit that connects between a discharge side and a suction side of a compressor; and a pressure valve that is provided in the bypass circuit and that opens in response to pressure on the discharge side. .