Refrigeration cycle device

Abstract

To restrain a disproportionation reaction.SOLUTION: In a refrigeration cycle device, a refrigerant circuit is filled with a refrigerant. The refrigerant includes a refrigerant having the property of producing a disproportionation reaction. The refrigerant circuit is provided with a bypass pipe connecting a discharge side pipe and a suction side pipe of a compressor. The refrigeration cycle device comprises a solenoid valve for controlling the passage of the refrigerant flowing through the bypass pipe, and a control unit for controlling the opening / closing of the solenoid valve on the basis of the discharge side pressure of the compressor and the temperature of the compressor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a refrigeration cycle device. [Background technology]

[0002] The R410A refrigerant, which is the mainstream refrigeration and freezing equipment, and commercial air conditioners, has a high global warming potential (GWP) of 2090, and in order to prevent global warming, it is necessary to switch to refrigerants with lower GWP values. For example, R1234yf, R1132(E), R1123, etc. have been proposed as next-generation low-GWP candidate refrigerants.

[0003] When R1123 and R1132(E) are used as components of mixed refrigerants, if a disproportionation reaction (autolysis reaction) occurs, a large amount of heat is released and the pressure rises, so ensuring the reliability of the compressor and refrigeration cycle becomes an issue. It is known that disproportionation reactions occur when high energy is added in an excessively high-temperature and high-pressure refrigerant atmosphere.

[0004] Patent Document 1 discloses a system configuration for suppressing the rotation speed of a compressor based on a disproportionation reaction pressure value of a refrigerant calculated from the discharge gas temperature of the refrigerant discharged from the compressor and the condenser outlet temperature as a means for suppressing a disproportionation reaction. Patent Document 2 discloses a configuration in which a pressure-vulnerable portion is provided in a part of the outer shell of the compressor, and when a disproportionation reaction occurs, the working fluid is discharged to the outside, and the motor drive device that controls the compressor's motor is destroyed by a vulnerable member, thereby stopping the compressor. Patent Document 3 discloses a configuration in which high and low pressure bypass piping is provided to connect the discharge side piping and the suction side piping of the compressor, and the bypass circuit is opened and closed by a fusible plug or a pressure valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6289611 [Patent Document 2] Patent No. 6805794 [Patent Document 3] Patent No. 6857815 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 has a problem that the disproportionation reaction cannot be sufficiently suppressed when the effect of reducing the pressure and temperature by suppressing the rotation speed of the compressor is poor. For example, in the case of a scroll compressor, regardless of the rotation speed, the refrigerant sucked in at the suction pressure is compressed to the discharge pressure based on the compression ratio set by the scroll tooth profile, so it is considered that the discharge pressure will not be reduced simply by lowering the rotation speed. In addition, if the refrigerant circulation amount decreases due to the suppression of the rotation speed, the heat dissipation effect of the refrigerant flowing in the sealed container will be weakened, and the temperature reduction may not be sufficient.

[0007] The technology described in Patent Document 2 has a safety issue because the pressure-vulnerable portion of the compressor outer casing is destroyed and high-temperature, high-pressure refrigerant is released to the outside. In particular, in the case of products used in densely populated residential areas or stores, there is a concern that explosion sounds due to the destruction and smoke, etc. will be generated due to the release of refrigerant. Furthermore, if the pressure-vulnerable portion is destroyed, the product becomes unusable and needs to be replaced, which is inconvenient.

[0008] In the technology described in Patent Document 3, the disproportionation reaction occurs under excessively high temperature and pressure conditions, so that opening and closing with a fusible plug or pressure valve is only able to sense either the temperature or the pressure, and furthermore, because sensing is physical, there is a concern that reaction delays and deterioration over time, such as corrosion, may occur.

[0009] The present invention has been made in consideration of such problems, and has an object to suppress the disproportionation reaction. [Means for solving the problem]

[0010] The present invention is a refrigeration cycle device in which a refrigerant circuit is filled with a refrigerant, the refrigerant including a refrigerant having a property of causing a disproportionation reaction, the refrigerant circuit is provided with a bypass piping connecting a discharge side piping and a suction side piping of a compressor, and is equipped with a solenoid valve that controls the passage of refrigerant flowing through the bypass piping, and a control unit that controls opening and closing of the solenoid valve based on the discharge side pressure of the compressor and the temperature of the compressor. Effect of the Invention

[0011] According to the present invention, the disproportionation reaction can be suppressed. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing the refrigeration cycle of the air conditioner. [Diagram 2] FIG. [Diagram 3] 13 is a flowchart showing an example of a solenoid valve control process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] FIG. 1 is a diagram showing the refrigeration cycle of an air conditioner 1. Here, the air conditioner 1 is an example of a refrigeration cycle device. Examples of refrigerants circulating through the refrigeration cycle include mixed refrigerants obtained by mixing R1234yf with R1132(E), mixed refrigerants obtained by mixing R1234yf with R1123, and mixed refrigerants in which R1234yf is replaced with R1234ze. The air conditioner 1 of this embodiment uses such mixed refrigerants and suppresses disproportionation reactions. The refrigeration cycle device is not limited to the air conditioner 1, and may be, for example, a refrigerator.

[0014] The air conditioner 1 includes an outdoor unit 1A and an indoor unit 1B. The outdoor unit 1A includes a compressor 2, an oil separator 3, a four-way valve 4, an outdoor fan 5, an outdoor heat exchanger 6, a heating expansion valve 7, and a receiver 8. The compressor 2 compresses a low-temperature, low-pressure gas refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. An accumulator 15 is provided in a suction-side refrigerant pipe 13 of the compressor 2, and an oil separator 3 is provided in a discharge-side refrigerant pipe 14 of the compressor 2. The oil accumulated in the oil separator 3 is returned to the compressor 2 via an oil return pipe 12. A pressure sensor 21 is provided in the discharge-side refrigerant pipe 14 of the compressor 2 to detect the pressure in the pipe, i.e., the discharge-side pressure of the compressor 2. In addition, a temperature sensor 22 is provided in the discharge-side refrigerant pipe 14 of the compressor 2 to detect the temperature of the compressor 2 (compressor temperature).

[0015] In the outdoor heat exchanger 6, heat exchange takes place between the refrigerant flowing through its heat transfer tubes and the outside air sent in by the outdoor fan 5. The outdoor heat exchanger 6 operates as a condenser or an evaporator by switching the four-way valve 4. The outdoor fan 5 is installed near the outdoor heat exchanger 6 and sends outside air to the outdoor heat exchanger 6. The expansion valve 7 has the function of reducing the pressure of the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 6 and the indoor heat exchanger 11). The refrigerant reduced in pressure in the expansion valve 7 is led to the "evaporator" (the other of the outdoor heat exchanger 6 and the indoor heat exchanger 11).

[0016] The indoor unit 1B is equipped with an expansion valve 9, an indoor fan 10, and an indoor heat exchanger 11. In the indoor heat exchanger 11, heat exchange takes place between the refrigerant flowing through its heat transfer tube and the indoor air sent in from the indoor fan 10. The indoor heat exchanger 11 operates as a condenser or an evaporator by switching the four-way valve 4. The indoor fan 10 is installed near the indoor heat exchanger 11. The indoor fan 10 sends indoor air to the indoor heat exchanger 11. The outdoor unit 1A and the indoor unit 1B are connected by a connecting refrigerant piping 16 to form a closed refrigeration cycle.

[0017] Furthermore, in this embodiment, a bypass pipe 17 is provided to connect the suction side refrigerant pipe 13 and the discharge side refrigerant pipe 14 of the compressor 2, and a solenoid valve 18 is provided in the bypass pipe 17. More specifically, the bypass pipe 17 is provided in the suction side refrigerant pipe 13 between the four-way valve 4 and the accumulator 15, and between the discharge side refrigerant pipe 14. The outdoor unit 1A is also provided with a control unit 23 that controls the opening and closing of the solenoid valve 18. The control unit 23 includes a CPU, RAM, ROM, etc. (not shown), and controls the solenoid valve 18 by executing a program stored in the ROM, etc. As another example, the control unit 23 may be configured by a circuit, etc.

[0018] When the air conditioner 1 is in cooling operation, the mixture of high-temperature, high-pressure gaseous refrigerant and oil discharged from the compressor 2 is separated into refrigerant and oil in the oil separator 3. The separated oil is returned directly to the oil reservoir at the bottom of the compressor 2. The separated refrigerant passes through the four-way valve 4 and condenses by dissipating heat to the outside air in the outdoor heat exchanger 6, becoming a high-pressure liquid refrigerant. After passing through the receiver 8, the liquid refrigerant flows through the connecting refrigerant pipe 16 to the indoor unit 1B side, where it is decompressed by the action of the cooling expansion valve 9 into a low-temperature, low-pressure gas-liquid two-phase state, and evaporates by absorbing heat from the indoor air in the indoor heat exchanger 11. The refrigerant evaporated in the indoor heat exchanger 11 returns to the outdoor unit 1A through the connecting refrigerant pipe 16, flows to the compressor 2 through the four-way valve 4, and is compressed again in the compressor 2.

[0019] Next, the case where the air conditioner 1 performs heating operation will be described. In the case of heating operation, the refrigerant flow path is switched from that in the case of cooling operation by the four-way valve 4. In the case of heating operation, the mixture of high-temperature and high-pressure gaseous refrigerant and oil discharged from the compressor 2 is separated into refrigerant and oil by the oil separator 3. The separated oil is directly returned to the oil reservoir at the bottom of the compressor 2. The separated refrigerant flows to the indoor unit 1B side through the four-way valve 4 and the connecting refrigerant pipe 16. The refrigerant that entered the indoor unit 1B is condensed by releasing heat to the indoor air in the indoor heat exchanger 11, and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows to the outdoor unit 1A side through the connecting refrigerant pipe 16. The high-pressure liquid refrigerant that entered the outdoor unit 1A is decompressed by the heating expansion valve 7, becomes a low-temperature low-pressure gas-liquid two-phase state, flows to the outdoor heat exchanger 6, and evaporates by absorbing heat from the outdoor air, becoming a gaseous refrigerant. The refrigerant that has become gaseous in the outdoor heat exchanger 6 flows through the four-way valve 4 to the compressor 2, where it is compressed again.

[0020] 2 is a vertical cross-sectional view of the compressor 2. The compressor 2 of this embodiment is a scroll compressor having an over-compression valve 37. The compressor 2 is a high-pressure chamber type compressor configured such that the discharge gas compressed by the compression mechanism 31 is discharged into the sealed container 30, and the pressure inside the sealed container 30 becomes approximately the discharge pressure.

[0021] In the compressor 2 shown in Fig. 2, a compression mechanism section 31 and an electric motor section 32 are housed in a substantially cylindrical sealed container (high-pressure container) 30. The compression mechanism section 31 includes a fixed scroll 31a and an orbiting scroll 31b, and is disposed in the upper space of the sealed container 30. An over-compression valve 37 and an over-compression valve retaining plate 38 are provided on the upper portion of the compression mechanism section 31, and when the pressure becomes excessive, the over-compression valve 37 opens to reduce the pressure. The electric motor section 32 includes a stator 32a and a rotor 32b. The compressor 2 is structured such that the rotation of the electric motor section 32 is transmitted to the compression mechanism section 31 by a rotating shaft 33.

[0022] The compressor 2 further includes a suction pipe 34, a discharge pipe 35, and an oil return pipe 36, which allow fluid to flow in and out of the sealed container 30. The suction pipe 34 serves as an inlet for allowing refrigerant to flow into the sealed container 30, and is connected to the suction side refrigerant pipe 13 shown in Fig. 1. The discharge pipe 35 serves as an outlet for discharging a mixture of refrigerant and a small amount of oil, and is connected to the discharge side refrigerant pipe 14 shown in Fig. 1. The oil return pipe 36 serves as an inlet for returning the oil separated from the mixture to the inside of the sealed container 30, and is connected to the oil return pipe 12 shown in Fig. 1.

[0023] When the electric motor unit 32 is operated, its rotation is transmitted to the compression mechanism unit 31 by the rotary shaft 33, causing the orbiting scroll 31b to orbit. As the orbiting scroll 31b and the fixed scroll 31c move relative to each other, the refrigerant is sucked from the suction pipe 34 into the compression mechanism unit 31 and compressed.

[0024] Next, the control of the solenoid valve 18 will be described. The circuit including the bypass piping 17 is used to reduce the startup load of the air conditioner 1. In the bypass circuit connecting the discharge side refrigerant piping 14 and the suction side refrigerant piping 13 of the compressor 2, by opening the solenoid valve 18, the pressure inside the compressor 2 is balanced to the low pressure side, and the high temperature discharge side refrigerant and the low temperature suction side refrigerant are mixed together, lowering the temperature of the discharge side refrigerant. This makes it possible to reduce the pressure and temperature by opening and closing the solenoid valve 18 for about 30 seconds.

[0025] In the air conditioner 1 of this embodiment, a bypass circuit including this bypass piping 17 is used to suppress the disproportionation reaction. Specifically, the control unit 23 performs the solenoid valve control process shown in FIG. 3. FIG. 3 is a flowchart showing the solenoid valve control process. First, in step S100, the control unit 23 acquires the discharge side pressure from the pressure sensor 21. Next, in step S102, the control unit 23 acquires the compressor temperature from the temperature sensor 22.

[0026] Next, in step S104, the control unit 23 compares the acquired discharge pressure with a preset first pressure threshold, and compares the acquired compressor temperature with a preset first temperature threshold. Then, the control unit 23 checks whether the discharge pressure and the compressor temperature satisfy a first condition. Here, the first condition is that the acquired discharge pressure is higher than the first pressure threshold, and the acquired compressor temperature is higher than the first temperature threshold. If the first condition is satisfied (Y in step S104), the control unit 23 opens the solenoid valve 18 (step S106). Here, the first pressure threshold and the first temperature threshold are the pressure and the temperature at which the disproportionation reaction occurs, respectively. The first pressure threshold is preferably 4.3 MPaG, for example. The first temperature threshold is preferably 130° C., for example. Since the first pressure threshold and the first temperature threshold are set in this way, the solenoid valve 18 can be opened before the disproportionation reaction occurs.

[0027] If the first condition is not satisfied, that is, if at least either the acquired discharge pressure is equal to or lower than the first pressure threshold or the acquired compressor temperature is equal to or lower than the first temperature threshold (N in step S104), the control unit 23 advances the process to step S100. In this case, the control unit 23 periodically repeats the processes of steps S100 to S104 until the discharge pressure and the compressor temperature satisfy the first condition. In this way, by opening the solenoid valve 18 when the first condition is satisfied, the disproportionation reaction can be suppressed.

[0028] After the process of step S106, in step S108, the control unit 23 again acquires the discharge side pressure from the pressure sensor 21. Next, in step S110, the control unit 23 acquires the compressor temperature from the temperature sensor 22. Next, in step S112, the control unit 23 compares the acquired discharge side pressure with a preset second pressure threshold, and compares the acquired compressor temperature with a preset second temperature threshold. Here, the second pressure threshold is set to a value equal to the first pressure threshold. Also, the second temperature threshold is set to a value equal to the first temperature threshold.

[0029] Then, the control unit 23 checks whether the discharge side pressure and temperature satisfy a second condition. Here, the second condition is that the acquired discharge side pressure is lower than a second pressure threshold and the acquired compressor temperature is lower than a second temperature threshold. If the second condition is satisfied (Y in step S112), the control unit 23 closes the solenoid valve 18 (step S114). Thereafter, the control unit 23 advances the process to step S100, and periodically repeats the processes of steps S100 to S104 until the discharge side pressure and the compressor temperature satisfy the first condition. In this way, if the second condition is satisfied, the solenoid valve 18 is closed, thereby preventing the discharge side pressure and the temperature of the compressor 2 from dropping too much.

[0030] On the other hand, if the second condition is not satisfied, that is, if at least one of the following cases is true: the acquired discharge pressure is equal to or higher than the second pressure threshold value, or the acquired compressor temperature is equal to or higher than the second temperature threshold value (N in step S112), the control unit 23 proceeds to step S108. In this case, the control unit 23 periodically repeats the processes of steps S108 to S112 until the discharge pressure and the compressor temperature satisfy the second condition.

[0031] As described above, the air conditioner 1 of this embodiment performs a process to prevent disproportionation reactions based on not only the discharge pressure of the compressor 2 or only the temperature of the compressor 2, but both of them. Disproportionation reactions occur in an excessively high-temperature and high-pressure refrigerant atmosphere. Therefore, in order to suppress the disproportionation reaction, it is necessary to quickly reduce the high temperature and high pressure. Therefore, in this embodiment, when the compressor temperature and pressure reach or exceed the threshold value, the solenoid valve 18 of the circuit including the bypass pipe 17 is opened to reduce the discharge pressure and the compressor temperature. This makes it possible to prevent the disproportionation reaction from occurring.

[0032] It should be noted that the present invention is not limited to the specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims, for example, by applying a modified example of one embodiment to another embodiment.

[0033] As a first modification, the second pressure threshold value referred to in the solenoid valve control process may be lower than the first pressure threshold value, and the second temperature threshold value may be lower than the first temperature threshold value, thereby preventing the solenoid valve 18 from being frequently opened and closed.

[0034] As a second modified example, the surface temperature of the compressor 2 may be acquired as the compressor temperature. Here, the surface temperature of the compressor 2 is detected by a temperature sensor provided on the surface of the compressor 2.

[0035] As a third modified example, the control unit 23 may control the solenoid valve 18 based on the discharge pressure and compressor temperature of the compressor 2, and the specific control method is not limited to the embodiment. For example, the control unit 23 may further adjust the opening degree of the solenoid valve 18, for example, increasing the opening degree of the solenoid valve 18 as the discharge pressure or the compressor temperature increases. [Explanation of symbols]

[0036] 1. Air conditioner 1A outdoor unit 1B Indoor unit 2. Compressor 3 Oil separator 4. Four-way valve 5 Outdoor fan 6 Outdoor heat exchanger 7 Expansion valve 8 Receiver 9 Expansion valve 10 Indoor Fan 11 Indoor heat exchanger 13 Suction side refrigerant piping 14 Discharge side refrigerant piping 15 Accumulator 16 Refrigerant connection piping 17 Bypass piping 18 Solenoid valve 21 Pressure Sensor 22 Temperature Sensor 23 Control Unit 31 Compression mechanism 31a Fixed Scroll 31b Swivel Scroll 32 Electric motor section 32a stator 32b Rotor 33 Rotation axis 34 Suction pipe 35 Discharge piping 36 Oil return pipe 37 Overcompression valve 38 Overcompression valve restraining plate

Claims

1. A refrigeration cycle device in which a refrigerant circuit is filled with a refrigerant, The refrigerant includes a refrigerant that has a property of causing a disproportionation reaction, The refrigerant circuit is provided with a bypass pipe connecting a discharge side pipe and a suction side pipe of the compressor, a solenoid valve for controlling the passage of the refrigerant through the bypass pipe; a control unit that controls opening and closing of the solenoid valve based on a discharge side pressure and a compressor temperature of the compressor; A refrigeration cycle device comprising:

2. The refrigeration cycle apparatus according to claim 1 , wherein the control unit opens the solenoid valve when the discharge side pressure is equal to or higher than a first pressure threshold and the compressor temperature is equal to or higher than a first temperature threshold.

3. The refrigeration cycle apparatus according to claim 2 , wherein the control unit closes the solenoid valve when the discharge side pressure is less than a second pressure threshold and the compressor temperature is less than a second temperature threshold.

4. 2. The refrigeration cycle apparatus according to claim 1, wherein the refrigerant capable of causing a disproportionation reaction is a mixed refrigerant containing R1132(E) or R1123.

5. The refrigeration cycle apparatus according to claim 1 , wherein the compressor is a scroll compressor having an overcompression valve.

6. The refrigeration cycle apparatus according to claim 1 , wherein the compressor temperature is acquired by a temperature sensor provided in the discharge side pipe of the compressor.

7. The refrigeration cycle apparatus according to claim 1 , wherein the compressor temperature is acquired by a temperature sensor provided on a surface of the compressor.

8. 2. The refrigeration cycle apparatus according to claim 1, wherein the compressor is of a high-pressure chamber type in which discharge gas compressed by a compression mechanism is discharged into a sealed container of the compressor, and the pressure inside the sealed container becomes approximately the discharge pressure.

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