Refrigeration cycle equipment

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 Art

[0002] The R410A refrigerant, which is the mainstream in refrigerators, freezers, commercial air conditioners, etc., has a high global warming potential (GWP) of 2090, and it is necessary to change to a refrigerant with a low GWP value for the purpose of global warming prevention. For example, as next-generation low-GWP candidate refrigerants, R1234yf, R1132(E), R1123, etc. have been proposed.

[0003] When R1123 or R1132(E) is used as a component of a mixed refrigerant, if a disproportionation reaction (self-decomposition reaction) occurs, the pressure will increase with a large amount of heat release, so ensuring the reliability of the compressor and the refrigeration cycle becomes an issue. It is known that the disproportionation reaction occurs when high energy is added in a refrigerant atmosphere that becomes excessively high temperature and high pressure, starting from this point.

[0004] Patent Document 1 discloses a system configuration that suppresses the rotation speed of a compressor based on the disproportionation reaction pressure value of the refrigerant obtained from the discharge gas temperature of the refrigerant discharged from the compressor and the condenser outlet temperature as a means for suppressing the disproportionation reaction. Patent Document 2 discloses a configuration in which a pressure vulnerable part is provided in a part of the outer shell of the compressor, and when the disproportionation reaction occurs, the working fluid is released to the outside, and the compressor is stopped by destroying the motor drive device that controls the motor of the compressor with a vulnerable member. Patent Document 3 discloses a configuration in which a high-low pressure bypass pipe that connects the discharge side pipe and the suction side pipe of the compressor is provided, 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 Document 2

[0006] However, the technology described in Patent Document 1 has the problem that disproportionation reactions cannot be sufficiently suppressed when the effect of reducing pressure and temperature by suppressing the compressor rotation speed is insufficient. For example, in the case of a scroll compressor, regardless of the rotation speed, the refrigerant drawn in by the suction pressure is compressed to the discharge pressure based on the compression ratio set by the scroll tooth profile, so it is conceivable that the discharge pressure will not decrease simply by reducing the rotation speed. In addition, if the amount of refrigerant circulated decreases due to the suppression of the rotation speed, the heat dissipation effect of the refrigerant flowing in the sealed container will weaken, and it is conceivable that the temperature reduction will not be sufficient.

[0007] The technology described in Patent Document 2 raises safety concerns because the pressure-vulnerable part of the compressor casing ruptures, releasing high-temperature, high-pressure refrigerant to the outside. In particular, for products used in densely populated residential areas or shops, there are concerns about the explosion noise and smoke generated by the release of refrigerant that may occur when the rupture occurs. Furthermore, if the pressure-vulnerable part is ruptured, the product becomes unusable and must be replaced, resulting in poor convenience.

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

[0009] This invention has been made in view of the above problems and aims to suppress disproportionation reactions. [Means for solving the problem]

[0010] The present invention relates to a refrigeration cycle device in which a refrigerant is filled into a refrigerant circuit, wherein the refrigerant includes a refrigerant that undergoes a disproportionation reaction, the refrigerant circuit is provided with a bypass pipe connecting the discharge side pipe and the suction side pipe of a compressor, a solenoid valve that controls the passage of the refrigerant flowing through the bypass pipe, and a control unit that controls the opening and closing of the solenoid valve based on the discharge side pressure of the compressor and the temperature of the compressor, wherein the compressor temperature is The discharge side piping of the compressor or the surface of the compressor The temperature sensor located at the above location acquires the value, and the control unit determines that the discharge side pressure is a first pressure threshold. Higher than, Furthermore, the compressor temperature is the first temperature threshold. Higher In that case, The solenoid valve is opened, and the discharge pressure is less than a second pressure threshold (which is less than or equal to the first pressure threshold), and the compressor temperature is less than a second temperature threshold (which is less than or equal to the first temperature threshold), and the solenoid valve is closed. The opening and closing of the solenoid valve is controlled. [Effects of the Invention]

[0011] According to the present invention, disproportionation reactions can be suppressed. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram showing the refrigeration cycle of an air conditioner. [Figure 2] This is a cross-sectional view of the compressor. [Figure 3] This is a flowchart showing the solenoid valve control process. An example is shown in the figure. [Modes for carrying out the invention]

[0013] Figure 1 shows the refrigeration cycle of the air conditioner 1. Here, the air conditioner 1 is an example of a refrigeration cycle device. Examples of refrigerants circulating in the refrigeration cycle include a mixed refrigerant of R1234yf and R1132(E), a mixed refrigerant of R1234yf and R1123, and a mixed refrigerant in which R1234yf is replaced with R1234ze. The air conditioner 1 of this embodiment suppresses disproportionation reactions while using such a mixed refrigerant. Note that the refrigeration cycle device is not limited to the air conditioner 1, but may be a refrigerator, for example.

[0014] The air conditioner 1 comprises an outdoor unit 1A and an indoor unit 1B. The outdoor unit 1A comprises 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 low-temperature, low-pressure gaseous refrigerant and discharges it as high-temperature, high-pressure gaseous refrigerant. An accumulator 15 is provided in the suction-side refrigerant piping 13 of the compressor 2, and an oil separator 3 is provided in the discharge-side refrigerant piping 14 of the compressor 2. The oil accumulated in the oil separator 3 is returned to the compressor 2 via the oil return piping 12. A pressure sensor 21 is provided in the discharge-side refrigerant piping 14 of the compressor 2 to detect the pressure in the piping, i.e., the discharge-side pressure of the compressor 2. In addition, a temperature sensor 22 is provided in the discharge-side refrigerant piping 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 supplied by the outdoor fan 5. The outdoor heat exchanger 6 operates as either 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 supplies outside air to it. The expansion valve 7 has the function of reducing the pressure of the refrigerant condensed in the "condenser" (either the outdoor heat exchanger 6 or the indoor heat exchanger 11). The refrigerant reduced in pressure by the expansion valve 7 is then led to the "evaporator" (the other of the outdoor heat exchanger 6 or the indoor heat exchanger 11).

[0016] The indoor unit 1B includes an expansion valve 9, an indoor fan 10, and an indoor heat exchanger 11. Heat exchange takes place in the indoor heat exchanger 11 between the refrigerant flowing through its heat transfer tubes and the indoor air supplied by the indoor fan 10. The indoor heat exchanger 11 operates as either a condenser or an evaporator by switching a four-way valve 4. The indoor fan 10 is installed near the indoor heat exchanger 11. The indoor fan 10 supplies indoor air to the indoor heat exchanger 11. The parts of the outdoor unit 1A and the indoor unit 1B are connected by connecting refrigerant piping 16 to form a closed-cycle refrigeration cycle.

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

[0018] When the air conditioner 1 is operated in the cooling mode, the mixture of the high-temperature and high-pressure gaseous refrigerant and oil discharged from the compressor 2 is separated into the refrigerant and the oil by the oil separator 3. The separated oil is directly returned to the oil sump at the bottom inside the compressor 2. The separated refrigerant passes through the four-way valve 4 and radiates heat to the outside air in the outdoor heat exchanger 6 to be condensed into a high-pressure liquid refrigerant. The liquid refrigerant passes through the receiver 8 and then flows to the indoor unit 1B side through the connecting refrigerant pipe 16, is decompressed by the action of the expansion valve 9 for cooling to become a low-temperature and low-pressure gas-liquid two-phase state, and evaporates by absorbing the heat of 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 through the four-way valve 4 to the compressor 2, and is compressed again by 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 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 sump at the bottom inside the compressor 2; The separated refrigerant flows toward the indoor unit 1B through the four-way valve 4 and the connecting refrigerant pipe 16. The refrigerant that enters the indoor unit 1B condenses by releasing heat to the indoor air in the indoor heat exchanger 11 and becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows toward the outdoor unit 1A through the connecting refrigerant pipe 16. The high-pressure liquid refrigerant that enters the outdoor unit 1A is depressurized by the expansion valve for heating 7, becomes a low-temperature and low-pressure gas-liquid two-phase state, flows into the outdoor heat exchanger 6, evaporates by absorbing the heat of the outdoor air, and becomes gaseous refrigerant. The refrigerant that becomes gaseous in the outdoor heat exchanger 6 flows through the four-way valve 4 to the compressor 2 and is compressed again by the compressor 2.

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

[0021] In the compressor 2 shown in FIG. 2, the compression mechanism portion 31 and the electric motor portion 32 are housed in a substantially cylindrical sealed container (high-pressure container) 30. The compression mechanism portion 31 includes a fixed scroll 31a and a swivel scroll 31b and is disposed in the upper space of the sealed container 30. Further, an over-compression valve 37 and an over-compression valve holding plate 38 are provided above the compression mechanism portion 31, and when the pressure rises too much, the over-compression valve 37 can be opened to reduce the pressure. The electric motor portion 32 includes a stator 32a and a rotor 32b. The compressor 2 has a structure in which the rotation of the electric motor portion 32 is transmitted to the compression mechanism portion 31 by the rotating shaft 33.

[0022] The compressor 2 is further equipped with a suction pipe 34, a discharge pipe 35, and an oil return pipe 36, which allow fluid to enter and exit the building. The suction pipe 34 is the inlet for the refrigerant to flow into the sealed container 30 and is connected to the suction-side refrigerant pipe 13 shown in Figure 1. The discharge pipe 35 is the 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 Figure 1. The oil return pipe 36 is the inlet for returning the oil separated from the mixture back into the sealed container 30 and is connected to the oil return pipe 12 shown in Figure 1.

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

[0024] Next, the control of the solenoid valve 18 will be explained. The circuit including the bypass piping 17 is used to reduce the starting 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, opening the solenoid valve 18 balances the internal pressure of the compressor 2 to the low-pressure side, and the high-temperature discharge side refrigerant and the low-temperature suction side refrigerant mix together, thereby lowering the temperature of the discharge side refrigerant. As a result, the pressure and temperature can be reduced by opening and closing the solenoid valve 18 for about 30 seconds.

[0025] In the air conditioner 1 of this embodiment, the bypass circuit including the bypass piping 17 is used to suppress the disproportionation reaction. Specifically, the control unit 23 performs the solenoid valve control processing shown in Figure 3. Figure 3 is a flowchart of the solenoid valve control processing. First, in step S100, the control unit 23 obtains the discharge side pressure from the pressure sensor 21. Next, in step S102, the control unit 23 obtains 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. The control unit 23 then checks whether the discharge pressure and 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 temperature at which the disproportionation reaction occurs, respectively. The first pressure threshold is preferably, for example, 4.3 MPaG. The first temperature threshold is preferably, for example, 130°C. In this way, since the first pressure threshold and the first temperature threshold are set, the solenoid valve 18 can be opened before the disproportionation reaction occurs.

[0027] If the first condition is not met, that is, if the acquired discharge pressure is below the first pressure threshold, or if the acquired compressor temperature is below the first temperature threshold, the control unit 23 proceeds to step S100 (N in step S104). In this case, the control unit 23 periodically repeats the process from step S100 to step S104 until the discharge pressure and compressor temperature meet the first condition. In this way, by opening the solenoid valve 18 when the first condition is met, the disproportionation reaction can be suppressed.

[0028] After processing in step S106, in step S108, the control unit 23 again acquires the discharge 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 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 be equal to the first pressure threshold. Also, the second temperature threshold is set to be equal to the first temperature threshold.

[0029] The control unit 23 then checks whether the discharge pressure and temperature satisfy the second condition. Here, the second condition is that the acquired discharge pressure is lower than the second pressure threshold and the acquired compressor temperature is lower than the second temperature threshold. If the second condition is satisfied (Y in step S112), the control unit 23 closes the solenoid valve 18 (step S114). After that, the control unit 23 proceeds to step S100 and periodically repeats the process from steps S100 to S104 until the discharge pressure and compressor temperature satisfy the first condition. In this way, by closing the solenoid valve 18 when the second condition is satisfied, it is possible to prevent the discharge pressure and the temperature of the compressor 2 from dropping too low.

[0030] On the other hand, if the second condition is not met, that is, if the acquired discharge pressure is equal to or greater than the second pressure threshold, or if the acquired compressor temperature is equal to or greater than the second temperature threshold, the control unit 23 proceeds to step S108 in at least one of these cases (N in step S112). In this case, the control unit 23 periodically repeats the process from step S108 to step S112 until the discharge pressure and compressor temperature meet the second condition.

[0031] As described above, the air conditioner 1 of this embodiment performs a process to prevent disproportionation reaction based not only on the discharge pressure of the compressor 2 or only on the temperature of the compressor 2, but on both. Disproportionation reaction occurs in a refrigerant atmosphere that is excessively high in temperature and pressure. Therefore, in order to suppress disproportionation reaction, it is necessary to quickly reduce the high temperature and high pressure. Accordingly, in this embodiment, when the compressor temperature and pressure exceed a threshold, the solenoid valve 18 of the circuit including the bypass piping 17 is opened to lower the discharge pressure and compressor temperature. This prevents the occurrence of disproportionation reaction.

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

[0033] In this first modification, the second pressure threshold referenced in the solenoid valve control process may be lower than the first pressure threshold, and the second temperature threshold may be lower than the first temperature threshold. This prevents the solenoid valve 18 from being opened and closed too frequently.

[0034] As a second variation, the surface temperature of the compressor 2 may be obtained 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] Furthermore, as a third modification, 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 this embodiment. For example, the control unit 23 may further adjust the opening degree of the solenoid valve 18, such as increasing the opening degree as the discharge pressure and compressor temperature increase. [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 Receivers 9. Expansion valve 10 Indoor Fans 11 Indoor heat exchanger 13. Intake side refrigerant piping 14. Discharge side refrigerant piping 15 Accumulator 16. Connecting refrigerant 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 piping 35 Discharge piping 36. Oil return piping 37 Overcompression valve 38 Overcompression valve retaining plate

Claims

1. A refrigeration cycle device in which a refrigerant is filled into the refrigerant circuit, The aforementioned refrigerant includes a refrigerant that has the property of causing a disproportionation reaction. The refrigerant circuit is provided with a bypass pipe connecting the discharge side pipe and the suction side pipe of the compressor. A solenoid valve controls the passage of refrigerant through the bypass piping, A control unit that controls the opening and closing of the solenoid valve based on the discharge pressure and compressor temperature of the compressor, Equipped with, The compressor temperature is obtained by a temperature sensor provided on the discharge side piping of the compressor or on the surface of the compressor. The control unit controls the opening and closing of the solenoid valve, opening it when the discharge pressure is higher than a first pressure threshold and the compressor temperature is higher than a first temperature threshold, and closing the solenoid valve when the discharge pressure is less than a second pressure threshold (which is equal to or less than the first pressure threshold) and the compressor temperature is less than a second temperature threshold (which is equal to or less than the first temperature threshold).

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

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

4. The refrigeration cycle apparatus according to claim 1, wherein the compressor temperature is obtained by the temperature sensor.

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

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