Refrigeration cycle device

Abstract

This refrigeration cycle device comprises: a refrigerant circuit that includes a compressor that has a compression mechanism and a motor for driving the compression mechanism; a refrigerant that circulates through the refrigerant circuit; and a protection mechanism that is activated on the basis of the temperature inside the compressor, the pressure inside the compressor, or the value of the current flowing through the motor, and suppresses increases in at least one among the temperature and the pressure. The refrigerant is an ethylenic HFO refrigerant or a mixed refrigerant that includes an ethylenic HFO refrigerant. When V (cm3) is the stroke volume of the compression mechanism and Q (W) is the rated output of the motor, Q / V is 25–300.

Description

Refrigeration cycle equipment

[0001] This disclosure relates to a refrigeration cycle system.

[0002] Patent Document 1 discloses a refrigeration cycle device. This refrigeration cycle device comprises a refrigeration cycle circuit configured by connecting a compressor, condenser, expansion valve, and evaporator in a ring. The refrigeration cycle circuit is filled with a refrigerant containing 1,1,2-trifluoroethylene or difluoromethane. An accumulator is provided on the suction side of the compressor.

[0003] The compressor is equipped with a temperature-sensing switch. This switch is located in the communication passage connecting the compressor's discharge refrigerant space to the accumulator. The temperature-sensing switch opens when the temperature in the discharge refrigerant space reaches a predetermined temperature. This allows the refrigerant discharged from the compressor to be released into the accumulator. The compressor motor is equipped with a thermal protector. The thermal protector shuts off the input to the motor when the temperature rises, stopping the compressor. These temperature-sensing switch and thermal protector mechanisms suppress the rise in refrigerant temperature.

[0004] Japanese Patent Publication No. 2019-27654

[0005] The above-mentioned refrigeration cycle system is equipped with a temperature-sensing switch and a thermal protector as protective mechanisms that operate based on the temperature inside the compressor. Other refrigeration cycle systems may also be equipped with protective mechanisms that operate based on the pressure inside the compressor or the current value flowing through the motor coil. However, these protective mechanisms have the problem that they may not operate reliably depending on the rate at which the temperature, pressure, or current value rises.

[0006] This disclosure is made to solve the problems described above and aims to provide a refrigeration cycle device that can operate the protection mechanism more reliably.

[0007] The refrigeration cycle device according to this disclosure comprises a refrigerant circuit including a compressor having a compression mechanism and a motor that drives the compression mechanism; a refrigerant circulating in the refrigerant circuit; and a protective mechanism that operates based on the temperature inside the compressor, the pressure inside the compressor, or the current value flowing to the motor, and suppresses the rise of at least one of the temperature and the pressure, wherein the refrigerant is an ethylene-based HFO refrigerant or a mixed refrigerant containing an ethylene-based HFO refrigerant, and the stroke volume of the compression mechanism is V [cm ３ When the rated output of the motor is Q [W], Q / V is 25 or more and 300 or less.

[0008] According to this disclosure, the protection mechanism of the refrigeration cycle system can be made to operate more reliably.

[0009] This is a refrigerant circuit diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 1. This is a cross-sectional view showing the configuration of the compressor of a refrigeration cycle device according to Embodiment 1. This is a schematic diagram explaining the relationship between the normal operating range and the self-decomposition reaction range of a refrigeration cycle device according to Embodiment 1. This is a graph showing the relationship between Q / V and ΔT / ΔT_ARI60rps in a refrigeration cycle device according to Embodiment 1. This is a graph showing the relationship between Q / V and ΔP in a refrigeration cycle device according to Embodiment 1. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 2. This is a graph showing an example of the time change in the current value flowing to the motor when a compressor failure occurs in a refrigeration cycle device according to Embodiment 2. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 3. This is a graph showing an example of the time change in the current value flowing to the motor when a compressor failure occurs in a refrigeration cycle device according to Embodiment 3. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 4. This is a graph showing an example of the time change in temperature when a compressor failure occurs in a refrigeration cycle device according to Embodiment 4. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to a modified version of Embodiment 4. This is a graph showing an example of the temperature change when the compressor is in vacuum operation or a near-vacuum state in a refrigeration cycle device according to Embodiment 4. This is a graph showing an example of temperature change over time when a compressor failure occurs in a refrigeration cycle device according to Embodiment 5. This is a graph showing an example of temperature change over time when a compressor failure occurs in a refrigeration cycle device according to a comparative example. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 6. This is a graph showing an example of the change over time of discharge refrigerant pressure when a compressor failure occurs in a refrigeration cycle device according to Embodiment 6. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 7. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 8. This is a block diagram showing the schematic configuration of a refrigeration cycle device according to Embodiment 9.

[0010] The embodiments relating to this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below, and can be modified in various ways without departing from the spirit of this disclosure. Furthermore, this disclosure includes all possible combinations of the configurations shown in each of the embodiments described below. In particular, the combinations of components are not limited to the combinations in each embodiment, and components described in one embodiment can be applied to another embodiment. In addition, in the following description, terms indicating direction (e.g., "up," "down," "right," "left," "front," "back," etc.) may be used as appropriate to facilitate understanding, but these are for illustrative purposes only and do not limit this disclosure. Also, in each drawing, components with the same reference numerals are the same or equivalent, and this is common throughout the entire specification. Note that the relative dimensions or shapes of each component in each drawing may differ from those of the actual components.

[0011] Embodiment 1. A refrigeration cycle device according to Embodiment 1 will be described. Figure 1 is a refrigerant circuit diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. The refrigeration cycle device of this embodiment is used in refrigeration and air conditioning equipment such as air conditioners and refrigerators. As shown in Figure 1, the refrigeration cycle device 200 has a refrigerant circuit 201, a control device 300, and a protection mechanism 310. The refrigerant circuit 201 has a compressor 100, a four-way valve 103, an outdoor heat exchanger 104, a throttling device 105 such as an electronic expansion valve, and an indoor heat exchanger 106. The compressor 100, the four-way valve 103, the outdoor heat exchanger 104, the throttling device 105, and the indoor heat exchanger 106 are connected in a ring shape via refrigerant piping. Refrigerant is sealed in the refrigerant circuit 201. The refrigerant circulates through the refrigerant circuit 201.

[0012] The refrigerant used in this embodiment is an ethylene-based HFO refrigerant or a mixed refrigerant containing an ethylene-based HFO refrigerant. Ethylene-based HFO refrigerants include HFO1141 (fluoroethene), HFO1132(E) (trans-1,2-difluoroethene), HFO1132(Z) (cis-1,2-difluoroethene), HFO1132a (2,2-difluoroethene), HFO1123 (1,2,2-trifluoroethene), and HFO1114 (tetrafluoroethene). Mixed refrigerants containing an ethylene-based HFO refrigerant include, for example, R474A, R474B, and R479A. R474A and R474B are mixed refrigerants of R1132(E) and R1234yf. R479A is a mixed refrigerant of R1132(E), R32, and R1234yf.

[0013] The four-way valve 103 is configured to switch the flow of refrigerant in the refrigerant circuit 201. The four-way valve 103 is connected to the discharge side of the compressor 100 in the refrigerant circuit 201. Generally, in refrigeration and air conditioning systems such as air conditioners, the indoor heat exchanger 106 is mounted on the indoor unit installed inside a room. The compressor 100, four-way valve 103, outdoor heat exchanger 104, and throttling device 105 are mounted on the outdoor unit installed outside.

[0014] The control device 300 is configured to control the entire refrigerant circuit 201, including the compressor 100. The protection mechanism 310 is configured to operate based on the temperature or pressure inside the compressor 100. The temperature inside the compressor 100 refers to the temperature of parts that become relatively hot inside the compressor 100, such as the temperature of the high-pressure space inside the compressor 100, the discharge temperature of the compressor 100, and the temperature of the motor inside the compressor 100. The pressure inside the compressor 100 refers to the pressure of parts that become relatively high inside the compressor 100, such as the pressure of the high-pressure space inside the compressor 100 and the discharge pressure of the compressor 100. By providing the protection mechanism 310, the rise in temperature and pressure inside the compressor 100 can be suppressed.

[0015] Furthermore, the current flowing through the motor of the compressor 100 has a positive correlation with the temperature inside the compressor 100. For this reason, the protection mechanism 310 may be configured to operate based on the current flowing through the motor of the compressor 100. The rise in temperature and pressure inside the compressor 100 can also be suppressed by the protection mechanism 310 that operates based on the current value.

[0016] Figure 2 is a cross-sectional view showing the configuration of a compressor in a refrigeration cycle device according to this embodiment. In this embodiment, a single-cylinder rotary compressor is exemplified as the compressor. As shown in Figure 2, the compressor 100 includes a compression mechanism 20 for compressing refrigerant gas, a motor 30 for driving the compression mechanism 20, and a sealed container 10 that houses the compression mechanism 20 and the motor 30. The sealed container 10 includes a cylindrical body 11, an upper lid 12 that closes the upper opening of the body 11, and a lower lid 13 that closes the lower opening of the body 11. A discharge pipe 102 is provided in the upper lid 12. The compression mechanism 20 is located in the lower part of the sealed container 10. The motor 30 is located above the compression mechanism 20 within the sealed container 10.

[0017] The motor 30 has a stator 32 and a rotor 31. The stator 32 is fixed to the inner circumferential surface of the sealed container 10. The rotor 31 is provided on the inner circumferential side of the stator 32. The inner circumferential surface of the stator 32 and the outer circumferential surface of the rotor 31 face each other with an air gap in between. A rotating shaft 21 is fixed to the center of the rotor 31.

[0018] The stator 32 comprises a stator core 32a and a stator winding 32b wound around the stator core 32a. The weight of the stator winding 32b is preferably in the range of 50g to 500g, more preferably in the range of 100g to 450g, and even more preferably in the range of 150g to 400g. Generally, as the weight of the stator winding 32b increases, the amount of heat generated by the stator winding 32b when energized increases.

[0019] The rated output of motor 30 is Q [W]. The rated output of motor 30 can be determined based on the specifications of the compressor 100 or the refrigeration cycle device 200.

[0020] The compression mechanism 20 is connected to the rotor 31 by a rotating shaft 21. The rotational force of the motor 30 is transmitted to the compression mechanism 20 via the rotating shaft 21. The compression mechanism 20 compresses the refrigerant gas using the transmitted rotational force and discharges it into the sealed container 10. The inside of the sealed container 10 is filled with compressed high-temperature, high-pressure refrigerant gas.

[0021] The stroke volume of the compression mechanism 20 is V [cm] ３ The stroke volume V of the compression mechanism 20 can be determined based on the specifications of the compressor 100 or the refrigeration cycle device 200. The stroke volume V is preferably 1 cm ３ More than 200cm ３ The following range, more preferably 2 cm ３ Over 180cm ３ The following range, and more preferably 3 cm ３ More than 150cm ３ It is within the range of [the specified range].

[0022] Refrigerant oil 14 for lubricating the compression mechanism 20 is stored at the bottom of the sealed container 10. In Figure 2, the refrigerant oil 14 is hatched. An oil pump (not shown) is provided below the rotating shaft 21. As the rotating shaft 21 rotates, the oil pump draws up the refrigerant oil from the bottom of the sealed container 10 and supplies it to the sliding parts of the compression mechanism 20. This ensures the mechanical lubrication of the compression mechanism 20.

[0023] The rotating shaft 21 has a main shaft portion 21a, an eccentric shaft portion 21b, and a sub-shaft portion 21c. The main shaft portion 21a, the eccentric shaft portion 21b, and the sub-shaft portion 21c are arranged in this order along the axial direction of the rotating shaft 21. The rotor 31 of the motor 30 is fixed to the main shaft portion 21a by shrink fitting or press fitting. A cylindrical rolling piston 22 is slidably fitted to the eccentric shaft portion 21b.

[0024] The compression mechanism 20 includes a cylinder 23, a rolling piston 22, an upper bearing 24, a lower bearing 25, and vanes (not shown). The cylinder 23 is formed in a hollow cylindrical shape. Inside the cylinder 23 is a cylindrical space, i.e., a cylinder chamber 23a, with both ends in the axial direction open.

[0025] The cylinder chamber 23a houses an eccentric shaft 21b, a rolling piston 22, and vanes. The eccentric shaft 21b performs eccentric rotational motion within the cylinder chamber 23a as the rotation of the rotating shaft 21 occurs. The rolling piston 22 is fitted onto the outer circumference of the eccentric shaft 21b. The space formed by the inner circumferential surface of the cylinder 23 and the outer circumferential surface of the rolling piston 22 is partitioned by vanes.

[0026] The upper bearing 24 rotatably supports the main shaft portion 21a of the rotating shaft 21. The upper bearing 24 also serves as an end plate that closes one of the axial openings of the cylinder chamber 23a. The upper bearing 24 has an almost inverted T-shape when viewed from the side.

[0027] The lower bearing 25 rotatably supports the sub-shaft portion 21c of the rotating shaft 21. The lower bearing 25 also serves as an end plate that closes the other axial opening of the cylinder chamber 23a. The lower bearing 25 is approximately T-shaped when viewed from the side.

[0028] The cylinder 23 is provided with an intake port 23b for drawing refrigerant gas into the cylinder chamber 23a from outside the sealed container 10. The upper bearing 24 is provided with a discharge port (not shown) for discharging compressed refrigerant gas to the outside of the cylinder chamber 23a.

[0029] A discharge valve (not shown) is provided at the discharge port of the upper bearing 24. The discharge valve controls the timing of refrigerant gas discharge. Specifically, the discharge valve is closed until the pressure of the refrigerant gas in the cylinder chamber 23a rises to a predetermined pressure. When the pressure of the refrigerant gas in the cylinder chamber 23a rises above the predetermined pressure, the discharge valve opens, and the high-temperature, high-pressure refrigerant gas is discharged to the outside of the cylinder chamber 23a through the discharge port.

[0030] In the cylinder chamber 23a, the suction, compression, and discharge operations are repeated, so the refrigerant gas is discharged intermittently from the discharge port. This can generate noise such as pulsating sounds. To reduce noise, a discharge muffler 27 is attached to the outside of the upper bearing 24, that is, on the motor 30 side of the upper bearing 24, so as to cover the upper bearing 24. The discharge muffler 27 is provided with discharge holes. The refrigerant gas compressed in the cylinder chamber 23a passes through the discharge port, is discharged into the space inside the discharge muffler 27, and then discharged into the sealed container 10 from the discharge holes.

[0031] An intake muffler 101 is provided on the side of the sealed container 10. The intake muffler 101 is provided on the intake side of the compressor 100 to prevent liquid refrigerant from being directly drawn into the cylinder chamber 23a. Generally, the compressor 100 receives a mixture of low-pressure refrigerant gas and liquid refrigerant from an external refrigerant circuit. If liquid refrigerant flows into the cylinder chamber 23a and is compressed by the compression mechanism 20, it will cause the compression mechanism 20 to malfunction. For this reason, the intake muffler 101 separates the liquid refrigerant and refrigerant gas, and only the refrigerant gas is sent to the cylinder chamber 23a. The intake muffler 101 is connected to the intake port of the cylinder 23 by an intake connecting pipe 101a. The low-pressure refrigerant gas sent from the intake muffler 101 is drawn into the cylinder chamber 23a via the intake connecting pipe 101a.

[0032] In the compression mechanism 20, the rotational motion of the rotating shaft 21 causes the eccentric shaft portion 21b to rotate within the cylinder chamber 23a. As a result, the rolling piston 22 rotates eccentrically along the inner circumferential surface of the cylinder 23. The volume of the working chamber, partitioned by the inner circumferential surface of the cylinder 23, the outer circumferential surface of the rolling piston 22, and the vanes, increases or decreases with the rotation of the eccentric shaft portion 21b. First, the working chamber and the intake port come into contact, and low-pressure refrigerant gas is drawn into the working chamber. Next, the intake port is closed, the volume of the working chamber decreases, and the refrigerant gas inside the working chamber is compressed. Next, the working chamber and the discharge port come into contact. When the pressure of the refrigerant gas inside the working chamber reaches a predetermined pressure, the discharge valve opens, and the compressed refrigerant gas is discharged to the outside of the cylinder chamber 23a.

[0033] The high-temperature, high-pressure refrigerant gas discharged from the cylinder chamber 23a into the sealed container 10 via the discharge muffler 27 passes through the motor 30 and rises within the sealed container 10. The high-temperature, high-pressure refrigerant gas is discharged to the outside of the sealed container 10 from the discharge pipe 102 located at the top of the sealed container 10. The refrigerant discharged from the compressor 100 circulates through the refrigerant circuit 201 and returns to the intake muffler 101.

[0034] In this embodiment, a rotary compressor is exemplified as the compressor 100, but various types of compressors, such as scroll compressors, can be used as the compressor 100.

[0035] Next, the flow of refrigerant in the refrigerant circuit 201 will be explained. For example, in the heating operation of the air conditioner, the four-way valve 103 is switched to form the flow path shown by the solid line in Figure 1. The high-temperature, high-pressure refrigerant gas compressed by the compressor 100 flows through the four-way valve 103 into the indoor heat exchanger 106. The refrigerant gas that flows into the indoor heat exchanger 106 condenses and liquefies through heat exchange with the indoor air, becoming liquid refrigerant. The liquid refrigerant that flows out of the indoor heat exchanger 106 is depressurized by the throttling device 105 and flows into the outdoor heat exchanger 104 in a low-temperature, low-pressure two-phase state. The two-phase refrigerant that flows into the outdoor heat exchanger 104 evaporates and gasifies through heat exchange with the outdoor air, becoming refrigerant gas. The refrigerant gas that flows out of the outdoor heat exchanger 104 returns to the intake muffler 101 of the compressor 100 through the four-way valve 103. In other words, the refrigerant circulates in the refrigerant circuit as shown by the solid arrow in Figure 1. In the outdoor heat exchanger 104, which acts as an evaporator, the refrigerant absorbs heat from the outdoor air. In the indoor heat exchanger 106, which acts as a condenser, the indoor air is warmed by the heat released from the refrigerant.

[0036] During the cooling operation of the air conditioner, the four-way valve 103 is switched to form the flow path shown by the dashed line in Figure 1. The high-temperature, high-pressure refrigerant gas compressed by the compressor 100 flows through the four-way valve 103 into the outdoor heat exchanger 104. The refrigerant gas flowing into the outdoor heat exchanger 104 condenses and liquefies through heat exchange with the outdoor air, becoming liquid refrigerant. The liquid refrigerant flowing out of the outdoor heat exchanger 104 is depressurized by the throttling device 105, becoming a low-temperature, low-pressure two-phase state, and flows into the indoor heat exchanger 106. The two-phase refrigerant flowing into the indoor heat exchanger 106 evaporates and gasifies through heat exchange with the indoor air, becoming refrigerant gas. The refrigerant gas flowing out of the indoor heat exchanger 106 returns to the intake muffler 101 of the compressor 100 through the four-way valve 103. In other words, the refrigerant circulates through the refrigerant circuit as shown by the dashed arrow in Figure 1. When switching from heating to cooling operation, the indoor heat exchanger 106 changes from a condenser to an evaporator, and the outdoor heat exchanger 104 changes from an evaporator to a condenser. In the indoor heat exchanger 106, which is an evaporator, the indoor air is cooled as the refrigerant absorbs heat from the indoor air. In the outdoor heat exchanger 104, which is a condenser, the refrigerant releases heat to the outdoor air.

[0037] The ethylene-based HFO refrigerant used in this embodiment undergoes a disproportionation reaction when a certain amount of ignition energy is applied. Furthermore, when the temperature or pressure of the refrigerant exceeds a certain level, a chain reaction of disproportionation occurs, causing a significant increase in temperature and pressure. If a chain reaction of disproportionation occurs within the compressor 100, the sealed container 10 of the compressor 100 may be damaged. By mixing the ethylene-based HFO refrigerant with other refrigerants, the temperature and pressure at which the chain reaction of disproportionation occurs can be shifted to the high-temperature and high-pressure sides. Hereinafter, the disproportionation reaction may be referred to as a "self-decomposition reaction."

[0038] FIG. 3 is a schematic diagram for explaining the relationship between the normal operation range of the refrigeration cycle device according to the present embodiment and the self-decomposition reaction occurrence region. The horizontal direction in the figure represents pressure, and the vertical direction in the figure represents temperature. As shown in FIG. 3, the normal operation range of the refrigeration cycle device 200 is lower in temperature and pressure than the self-decomposition reaction occurrence region where the self-decomposition reaction of the refrigerant can occur. A protection margin range is provided between the normal operation range and the self-decomposition reaction occurrence region. The protection margin range is the range of temperature and pressure at which the protection mechanism 310 operates. The protection mechanism 310 operates when the temperature, pressure, or current value flowing through the motor 30 in the compressor 100 rises above a threshold value. When the protection mechanism 310 operates, the rise in the temperature and pressure of the refrigerant is suppressed.

[0039] When the operation of the compressor 100 cannot be controlled due to a failure of the compressor 100 or when a lock occurs in the compressor 100, an abnormality in temperature, pressure, or current value occurs. When these abnormalities occur, the temperature or pressure of the refrigerant may rise above the normal operation range. However, when the temperature or pressure of the refrigerant rises and reaches the protection margin range, the protection mechanism 310 operates, and the temperature and pressure of the refrigerant decrease. Therefore, the occurrence of the self-decomposition reaction of the refrigerant is prevented.

[0040] Examples of the protection mechanism 310 include a thermal protector, a current protector, a motor protector, etc. The thermal protector is a temperature protection mechanism that disconnects the circuit contact based on temperature and stops the operation of the compressor 100. The current protector is a current protection mechanism that disconnects the circuit contact based on the current value and stops the operation of the compressor 100. The motor protector is a protection mechanism having the functions of both the thermal protector and the current protector. The motor protector may be used instead of the thermal protector or the current protector.

[0041] In this embodiment, a one-stage or multi-stage protection mechanism is provided in the refrigeration cycle device 200. When a multi-stage protection mechanism is provided, the protection mechanism 310 includes a first protection mechanism and a second protection mechanism that operates after the first protection mechanism. Thereby, when an abnormality in temperature, pressure, or current value occurs, it is possible to reliably suppress an increase in temperature and pressure.

[0042] Generally, when the rate of increase in temperature or pressure is low, the protection mechanism 310 may not operate at a suitable timing. In this embodiment, by adjusting the rated output Q of the motor 30 and the stroke volume V of the compression mechanism 20, the rate of increase in temperature or pressure is increased so that the protection mechanism 310 operates more suitably.

[0043] FIG. 4 is a graph showing the relationship between Q / V and ΔT / ΔT_ARI60rps in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents Q / V. Q / V is the ratio of the rated output Q [W] of the motor 30 to the stroke volume V [cm ３ of the compression mechanism 20. The vertical axis of the graph represents ΔT / ΔT_ARI60rps. ΔT / ΔT_ARI60rps is a value obtained by normalizing the temperature rise ΔT of the stator winding 32b with the temperature rise ΔT_ARI60rps of the stator winding 32b under ARI conditions of 60 rps. The ARI conditions are condensation temperature / evaporation temperature = 54.4 / 7.2 °C, subcooling degree / superheat degree = 8.3 / 11.1 °C, and dew point method.

[0044] FIG. 5 is a graph showing the relationship between Q / V and ΔP in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents Q / V as in FIG. 4. The vertical axis of the graph represents the differential pressure ΔP [MPaG] between the discharge refrigerant pressure and the suction refrigerant pressure of the compressor 100.

[0045] As shown in FIGS. 4 and 5, the range of Q / V in which ΔT / ΔT_ARI60rps increases and the range of Q / V in which ΔP increases generally overlap. In other words, by adjusting the range of Q / V, both ΔT / ΔT_ARI60rps and ΔP can be increased.

[0046] Range A shown in Figures 4 and 5 is the range where Q / V is between 25 and 300. When Q / V is within range A, ΔT / ΔT_ARI60rps is 2 or greater, and ΔP is 2 or greater. The value of ΔT / ΔT_ARI60rps represents how easily the temperature rises inside the compressor 100. The value of ΔP represents how easily the pressure rises inside the compressor 100. Therefore, by setting Q / V to the range of 25 or more and 300 or less, a more rapid temperature rise and a more rapid pressure rise can be obtained inside the compressor 100, thereby enabling the protection mechanism 310 to operate more reliably.

[0047] Range B shown in Figures 4 and 5 is the range where Q / V is between 50 and 230. When Q / V is within range B, ΔT / ΔT_ARI60rps becomes 4 or greater, and ΔP becomes 2.3 or greater. Therefore, in order to reliably operate the protection mechanism 310, it is desirable that Q / V be within the range of 50 or greater and 230 or less.

[0048] The range C shown in Figures 4 and 5 is the range where Q / V is between 50 and 180. When Q / V is within range C, ΔT / ΔT_ARI60rps becomes 4 or greater, and ΔP becomes 2.4 or greater. Therefore, in order to reliably operate the protection mechanism 310, it is even more desirable that Q / V be within the range of 50 or greater and 180 or less.

[0049] As described above, the refrigeration cycle device 200 according to this embodiment includes a refrigerant circuit 201, a refrigerant circulating through the refrigerant circuit 201, and a protection mechanism 310. The refrigerant circuit 201 includes a compressor 100. The compressor 100 has a compression mechanism 20 and a motor 30 that drives the compression mechanism 20. The protection mechanism 310 operates based on the temperature inside the compressor 100, the pressure inside the compressor 100, or the current value flowing to the motor 30, and suppresses the rise of at least one of the temperature and pressure. The refrigerant is an ethylene-based HFO refrigerant or a mixed refrigerant containing an ethylene-based HFO refrigerant. The protection mechanism 310 includes a first protection mechanism and a second protection mechanism that operates after the first protection mechanism. The stroke volume of the compression mechanism 20 is V [cm ３ When the rated output of the motor 30 is Q [W], Q / V is between 25 and 300.

[0050] With this configuration, a more rapid temperature rise and a more rapid pressure rise can be obtained inside the compressor 100, thereby enabling the protection mechanism 310 to operate more reliably.

[0051] Embodiment 2. A refrigeration cycle device according to Embodiment 2 will be described. Figure 6 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 6, the compressor 100 is connected to the power supply 320 via a current protector 311, an inverter 301, and an overcurrent circuit breaker 312. Power is supplied from the power supply 320 to the compressor 100, passing through the overcurrent circuit breaker 312, the inverter 301, and the current protector 311 in that order.

[0052] The current protector 311 and the overcurrent circuit breaker 312 are mechanical current protection mechanisms installed in the power path between the power supply 320 and the compressor 100. The current protector 311 is attached to the compressor 100. The current protector 311 is provided as a first protection mechanism. The overcurrent circuit breaker 312 is provided as a second protection mechanism that operates after the first protection mechanism. The overcurrent circuit breaker 312 may also be a protective current interruption for the inverter 301. The first and second protection mechanisms are not operated and controlled by the same microcontroller, for example, but are designed to stop the compressor 100 independently. The inverter 301 is provided as part of the control device 300. The inverter 301 controls the frequency of the compressor 100.

[0053] If the compressor 100 malfunctions and its operation becomes uncontrollable, or if the compressor 100 locks up, an abnormal temperature may occur inside the compressor 100. Figure 7 is a graph showing an example of the time change in the current value flowing to the motor when a compressor malfunction occurs in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents the elapsed time since the malfunction occurred. The vertical axis of the graph represents the current value flowing to the motor 30.

[0054] As shown in Figure 7, if a malfunction occurs in the compressor 100, the abnormal operation of the compressor 100 will cause the current value to become higher than normal. The excessive current flowing through the motor 30 will cause the temperature of the motor 30 to rise. If a protection mechanism is not provided, the rise in the temperature of the motor 30 may cause a disproportionation reaction of the refrigerant.

[0055] In this embodiment, a current protector 311 is provided as a first protection mechanism. Therefore, at time t1, the current protector 311 is activated due to an increase in the current value. That is, the increase in the current value causes the bimetal of the current protector 311 to disconnect, and the power supply to the compressor 100 is cut off. This makes it possible to forcibly stop the compressor 100.

[0056] In this embodiment, an overcurrent circuit breaker 312 is provided as a second protection mechanism. The threshold current value at which the overcurrent circuit breaker 312 activates is greater than the threshold current value at which the current protector 311 activates. In other words, when an excessive current flows to the motor 30 due to a failure of the compressor 100, the overcurrent circuit breaker 312 activates after the current protector 311. Therefore, even if the bimetal of the current protector 311 fails due to some factor such as poor contact welding, the overcurrent circuit breaker 312 will activate at a subsequent time t2, and the power supply to the compressor 100 will be reliably cut off.

[0057] It is preferable that the overcurrent circuit breaker 312 is a manually reset type that does not automatically reset once activated. This ensures that power to the compressor 100 is reliably stopped in the event of a malfunction, thereby preventing disproportionation reactions.

[0058] As described above, in the refrigeration cycle device 200 according to this embodiment, the protection mechanism includes a first protection mechanism and a second protection mechanism that operates after the first protection mechanism.

[0059] With this configuration, even if the first protection mechanism fails to operate for some reason, the second protection mechanism can suppress the rise in temperature and pressure inside the compressor 100. Therefore, disproportionation reactions in the refrigerant can be prevented more reliably.

[0060] In the refrigeration cycle device 200 according to this embodiment, the first protection mechanism is a current protector 311 attached to the compressor 100. The second protection mechanism is an overcurrent circuit breaker 312 provided in the power path between the power supply 320 and the compressor 100 of the refrigeration cycle device 200.

[0061] Disproportionation of the refrigerant occurs due to temperature and pressure. When the motor current is high, the temperature of the motor 30 rises, and the temperature of the refrigerant rises. To reliably suppress the motor current, motor stopping by the current protector 311 is reliable. However, the current protector 311 may not operate due to its lifespan. Even in that case, the compressor 100 can be reliably stopped by the overcurrent circuit breaker 312, which has a threshold current value higher than the threshold current value of the current protector 311. Therefore, in a refrigeration cycle device 200 using ethylene-based HFO refrigerant or a mixed refrigerant containing ethylene-based HFO refrigerant, it is desirable to perform protection in the order described above.

[0062] Embodiment 3. A refrigeration cycle device according to Embodiment 3 will be described. Figure 8 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 8, the refrigeration cycle device 200 of this embodiment has the same configuration as the refrigeration cycle device 200 of Embodiment 2. In this embodiment, current protection by control and physical current protection are combined.

[0063] In this embodiment, the control device 300 performs protective control that reduces the output when the motor current exceeds a certain threshold. This protective control realizes the first protection mechanism. The compressor 100 is provided with a current protector 311. In addition, an overcurrent circuit breaker 312 is provided in the power path between the power supply 320 and the compressor 100. The current protector 311 and the overcurrent circuit breaker 312 are provided as a second protection mechanism. The threshold current value at which the current protector 311 operates and the threshold current value at which the overcurrent circuit breaker 312 operates are both greater than the threshold current value at which the protective control is executed. The protective control in the control device 300, the current protector 311, and the overcurrent circuit breaker 312 are all current protection mechanisms.

[0064] Figure 9 is a graph showing an example of the time change in the current value flowing to the motor when a compressor failure occurs in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents the elapsed time since the failure occurred. The vertical axis of the graph represents the current value flowing to the motor 30.

[0065] As shown in Figure 9, at time t1, protective control is executed due to an increase in the current value. This reduces the output (e.g., rotational speed) of the compressor 100. Alternatively, if the current value exceeds a certain threshold, the operation of the compressor 100 is stopped by protective control. Due to these protective controls, the current value usually decreases.

[0066] If the protective control fails and the current value does not decrease, the current protector 311 or the overcurrent circuit breaker 312 will activate at a subsequent time t2. When the current protector 311 or the overcurrent circuit breaker 312 activates, the power supply to the compressor 100 is stopped. This ensures that the compressor 100 is stopped reliably.

[0067] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protective control performed by the control device 300 based on the current value flowing through the stator winding 32b. The second protection mechanism is a current protector 311 provided on the compressor 100, or an overcurrent circuit breaker 312 provided in the power path between the power supply 320 of the refrigeration cycle device and the compressor 100.

[0068] With this configuration, even if current protection by protective control fails and the current value does not decrease, the compressor 100 can be reliably stopped by the current protector 311 or the overcurrent circuit breaker 312. When considering safe stopping to ensure the quality of the refrigeration cycle, protection by control is the best option. However, when using ethylene-based HFO refrigerant, there is a possibility of disproportionation reaction occurring. If a certain threshold temperature and pressure are exceeded, a rapid increase in pressure and temperature occurs due to the disproportionation reaction, so it is necessary to reliably stop the compressor 100 before this reaction occurs. Therefore, in this embodiment, if a control failure occurs, the compressor 100 is reliably stopped by stopping the motor with the current protector 311 or the overcurrent circuit breaker 312. Note that repeated stopping by the bimetal may cause deterioration of the bimetal. For this reason, by setting the threshold current value by control lower than the threshold current value for bimetal disconnection, a refrigeration cycle system with optimal safety devices can be provided.

[0069] Embodiment 4. A refrigeration cycle device according to Embodiment 4 will be described. Figure 10 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 10, a discharge pipe temperature sensor 313 is provided in the discharge pipe of the compressor 100. The discharge pipe temperature sensor 313 is attached to the outer wall surface of the discharge pipe and detects the temperature of the discharge pipe. The temperature of the discharge pipe is a correlation temperature that correlates with the temperature inside the compressor 100. The control device 300 performs protective control based on the temperature detected by the discharge pipe temperature sensor 313. This protective control realizes the first protective mechanism.

[0070] A mechanical thermal protector 314 is provided inside the compressor 100, including inside the motor 30 and the terminal section of the compressor 100. The thermal protector 314 is a second protection mechanism that protects the compressor 100 based on the temperature inside the compressor 100. The threshold temperature at which the thermal protector 314 activates is higher than the threshold temperature at which the control device 300 performs protection control. Furthermore, as will be described later, the threshold temperature at which the thermal protector 314 activates is set so that the thermal protector 314 activates after the control device 300 performs protection control.

[0071] In this embodiment, when the temperature rises abnormally due to factors such as a malfunction of the compressor 100 or no gas flow due to vacuum operation, the system operates as follows. Figure 11 is a graph showing an example of the change in temperature over time when a compressor failure occurs in the refrigeration cycle system according to this embodiment. The horizontal axis of the graph represents the elapsed time since the failure occurred. The vertical axis of the graph represents the temperature. The solid line in the graph represents the change in refrigerant temperature (or the temperature of the stator winding 32b). The long dashed line in the graph represents the change in the discharge pipe temperature of the compressor 100 (or the shell temperature, which will be described later).

[0072] As shown in Figure 11, when the refrigerant temperature rises due to a compressor 100 malfunction or the like, the discharge pipe temperature rises with a delay. A discrepancy occurs between the discharge pipe temperature and the refrigerant temperature. When the discharge pipe temperature exceeds the threshold temperature (time t1), the control device 300 performs temperature protection control, which stops the power supply to the motor 30. When temperature protection control is performed, the refrigerant temperature and discharge pipe temperature usually decrease.

[0073] If the refrigerant temperature does not decrease for any reason, the thermal protector 314 will activate at a subsequent time t2. When the thermal protector 314 activates, power to the compressor 100 is cut off. This ensures that the compressor 100 is stopped, thereby suppressing the occurrence of disproportionation reactions. The threshold temperature at which the thermal protector 314 activates is set to take into account the difference between the discharge pipe temperature and the refrigerant temperature, so that the thermal protector 314 activates after the protective control is executed by the control device 300.

[0074] Figure 12 is a block diagram showing a schematic configuration of a refrigeration cycle device according to a modified example of this embodiment. As shown in Figure 12, in this modified example, a shell temperature sensor 315 is provided instead of a discharge pipe temperature sensor 313. The shell temperature sensor 315 is attached to the outer wall surface of the sealed container 10 and detects the shell temperature of the compressor 100. The shell temperature of the compressor 100 is a correlated temperature that correlates with the temperature inside the compressor 100. Since the shell temperature changes with a lag behind the refrigerant temperature, it changes in the same way as the discharge pipe temperature shown in Figure 13. Temperature protection control by the control device 300 may be performed based on the shell temperature.

[0075] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protective control performed by the control device 300 based on the temperature inside the compressor 100 or a correlated temperature correlated with that temperature. The second protection mechanism is a thermal protector 314 provided in the compressor 100.

[0076] In this embodiment, considering the possibility that the first protection mechanism may not provide adequate protection, a more reliable mechanical thermal protector 314 is used as the second protection mechanism. This ensures that the occurrence of disproportionation reactions is reliably suppressed.

[0077] Disproportionation reactions occur due to temperature and pressure. By using a temperature sensor attached to the sealed container 10 or discharge pipe of the compressor 100 for protection control, the compressor 100 can be safely stopped, eliminating the need for sudden stops by adjusting the rotational speed of the compressor 100 or controlling the unit. For this reason, it is desirable to protect the compressor 100 by using temperature sensor protection control whenever possible.

[0078] However, depending on the mounting position, the temperature sensor attached to the sealed container 10 or the discharge pipe may not be able to accurately measure the refrigerant temperature. Figure 13 is a graph showing an example of temperature change when the compressor is in vacuum operation or close to it in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents time. The vertical axis of the graph represents temperature. The solid line in the graph represents the change in refrigerant temperature (or the temperature of the stator winding 32b) inside the compressor 100. The dashed line in the graph represents the change in shell top surface temperature and discharge pipe temperature.

[0079] If the circuit connected to the suction side of the compressor 100 becomes blocked (for example, the gas pipe being closed during cooling, or the expansion valve being clogged or blocked), the compressor 100 will enter a vacuum operation state or a state close to it. When the compressor 100 enters a vacuum operation state, there is no gas to draw in, and the flow of discharged gas also ceases. When there is no gas flow, the heat generated by the motor 30 cannot be transported out of the compressor 100, and as shown in Figure 13, the winding temperature and the gas refrigerant temperature around the winding rise. Also, because there is no gas flow, the difference between the temperature inside the compressor 100, especially near the motor 30, and the shell top surface temperature and discharge pipe temperature becomes large. For this reason, in the initial stages of temperature rise, the shell top surface temperature and discharge pipe temperature are much lower than the temperature inside the compressor 100. For this reason, if protective control is performed based on the shell top surface temperature or discharge pipe temperature, even if the temperature inside the compressor 100 rises to the temperature at which thermal protection should be performed, the protective control may be delayed or not performed at all. Furthermore, if the temperature sensor is removed from its proper mounting position, temperature protection control will not be performed at all.

[0080] In contrast, in this embodiment, a thermal protector 314 is provided as a second protection mechanism. The thermal protector 314 detects the temperature inside the compressor 100 and operates generally based on the refrigerant temperature. In this embodiment, when the refrigerant temperature rises due to abnormal operation, the power supply to the compressor 100 is forcibly cut off by the thermal protector 314, so that the compressor 100 can be reliably stopped.

[0081] Embodiment 5. A refrigeration cycle device according to Embodiment 5 will be described. The refrigeration cycle device 200 of this embodiment has the same configuration as the refrigeration cycle device 200 of Embodiment 4. However, in this embodiment, the first protection mechanism and the second protection mechanism are reversed compared to Embodiment 4. That is, in the refrigeration cycle device 200 of this embodiment, a thermal protector 314 is used as the first protection mechanism. The thermal protector 314 is installed inside the compressor 100 (inside the motor 30, the terminals of the compressor 100, etc.). The control device 300 performs protection control based on the temperature detected by the discharge pipe temperature sensor 313 or the shell temperature sensor 315. This protection control realizes the second protection mechanism.

[0082] When the temperature rises abnormally due to factors such as a malfunction of the compressor 100 or no gas flow due to vacuum operation, the system operates as follows. Figure 14 is a graph showing an example of the change in temperature over time when a compressor failure occurs in the refrigeration cycle system according to this embodiment. The horizontal axis of the graph represents the elapsed time since the failure occurred. The vertical axis of the graph represents the temperature. The solid line in the graph represents the change in refrigerant temperature (or the temperature of the stator winding 32b). The long dashed line in the graph represents the change in the discharge pipe temperature (or shell temperature) of the compressor 100.

[0083] As shown in Figure 14, if the refrigerant temperature rises due to a malfunction of the compressor 100 or the like, the discharge pipe temperature or shell temperature will rise with a delay. When the refrigerant temperature exceeds the threshold temperature of the thermal protector 314 (time t1), the thermal protector 314 activates and the power supply to the motor 30 is stopped.

[0084] If the thermal protector 314 fails to activate for any reason and the discharge pipe temperature or shell temperature exceeds the protection control threshold temperature (time t2), the control device 300 performs temperature protection control, which stops the power supply to the motor 30.

[0085] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is a thermal protector 314 provided on the compressor 100. The second protection mechanism is realized by protection control performed by the control device 300 based on the temperature inside the compressor 100 or a correlated temperature correlated with that temperature.

[0086] According to this embodiment, even if the first protection mechanism, the thermal protector 314, does not activate, the second protection mechanism performs temperature protection control based on the discharge pipe temperature or shell temperature, and the power supply to the motor 30 is stopped. This ensures that the compressor 100 is stopped and suppresses the occurrence of disproportionation reactions.

[0087] In this embodiment, in order to activate the thermal protector 314 before the protection control, the threshold temperature of the thermal protector 314 is set to be less than or equal to the threshold temperature of the protection control (threshold temperature of thermal protector 314 ≤ threshold temperature of protection control). The thermal protector 314 is more sensitive to changes in refrigerant temperature in the compressor 100 than the discharge pipe temperature sensor 313 and the shell temperature sensor 315. Therefore, when the refrigerant temperature rises, the temperatures detected by the discharge pipe temperature sensor 313 and the shell temperature sensor 315 become lower than the temperatures detected by the thermal protector 314. Consequently, the thermal protector 314 can be activated before the protection control not only when its threshold temperature is lower than the threshold temperature of the protection control, but also when its threshold temperature is the same as the threshold temperature of the protection control.

[0088] Disproportionation reactions increase rapidly when temperature and pressure exceed a certain threshold. Therefore, to ensure reliable protection, it is desirable to stop the motor 30 using a thermal protector 314 located inside the compressor 100. However, due to factors such as lifespan, the thermal protector 314 may not always operate reliably. For this reason, in this embodiment, a second protection mechanism is implemented: temperature protection control based on the discharge pipe temperature or shell temperature. This ensures that the compressor 100 is reliably stopped, thereby suppressing the occurrence of disproportionation reactions.

[0089] Figure 15 is a graph showing an example of the time change of temperature when a compressor failure occurs in a refrigeration cycle system according to the comparative example. In the comparative example shown in Figure 15, the refrigerant temperature reaches the disproportionation reaction temperature at time t3, before the discharge pipe temperature reaches the threshold temperature for protection control, and a disproportionation reaction occurs. Therefore, in order to suppress the occurrence of the disproportionation reaction as a second protection mechanism using temperature protection control based on the discharge pipe temperature or shell temperature, it is necessary to set the threshold temperature for protection control as shown in Figure 14, not Figure 15. That is, the threshold temperature for temperature protection control based on the discharge pipe temperature or shell temperature needs to be set to a temperature lower than the discharge pipe temperature or shell temperature obtained when the refrigerant temperature reaches the disproportionation reaction temperature.

[0090] Embodiment 6. A refrigeration cycle device according to Embodiment 6 will be described. Figure 16 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 16, a pressure sensor 316 is provided in the high-pressure piping on the discharge side of the compressor 100. The pressure sensor 316 detects the discharge refrigerant pressure, that is, the pressure inside the compressor 100. The control device 300 performs protective control based on the discharge refrigerant pressure. This protective control realizes the first protective mechanism.

[0091] Furthermore, a pressure switch 317 is provided in the high-pressure piping on the discharge side of the compressor 100. The pressure switch 317 is a second protection mechanism that provides pressure protection based on the discharge refrigerant pressure, i.e., the pressure inside the compressor 100. The threshold pressure at which the pressure switch 317 is activated is higher than the threshold pressure at which protection control is performed by the control device 300. When the pressure switch 317 is activated, power is cut off to the compressor 100.

[0092] It is desirable that the pressure switch 317 be a manually reset type that does not automatically reset once activated. If the pressure switch 317 is activated, there is a high probability that the pressure sensor 316 is faulty or there is a control malfunction. Therefore, by making the pressure switch 317 a manually reset type, it is possible to prevent the compressor 100 from restarting.

[0093] If the discharge refrigerant pressure of the compressor 100 rises abnormally due to a malfunction in the refrigeration cycle device 200, the system operates as follows. Figure 17 is a graph showing an example of the change in discharge refrigerant pressure over time when a compressor failure occurs in the refrigeration cycle device according to this embodiment. The horizontal axis of the graph represents the elapsed time since the failure occurred. The vertical axis of the graph represents the pressure.

[0094] As shown in Figure 17, if the discharge refrigerant pressure rises abnormally due to a malfunction of the compressor 100 or the like, protective control is executed at time t1. For example, if the discharge refrigerant pressure exceeds the protective control threshold pressure, the control device 300 reduces the rotational speed of the compressor 100 and executes protective control to suppress the rise in discharge refrigerant pressure. Furthermore, if the control device 300 cannot suppress the rise in discharge refrigerant pressure, it executes protective control to stop the operation of the compressor 100. Due to these protective controls, the discharge refrigerant pressure usually decreases.

[0095] If the discharge refrigerant pressure does not decrease for any reason, the pressure switch 317 will be activated at a subsequent time t2. When the pressure switch 317 is activated, power to the compressor 100 is cut off. This ensures that the compressor 100 is stopped.

[0096] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protective control performed by the control device 300 based on the pressure in the compressor 100. The second protection mechanism is a pressure switch 317 that operates based on the pressure in the compressor 100.

[0097] According to this embodiment, pressure protection can normally be performed by protective control using the pressure sensor 316. Even if protective control is not possible due to a malfunction of the pressure sensor 316 or a control failure, the compressor 100 can be forcibly stopped by the pressure switch 317. Therefore, disproportionation reactions can be prevented more reliably.

[0098] In typical refrigeration cycle systems, pressure protection is provided only by a pressure switch, and malfunctions of the pressure switch are not anticipated. However, when using ethylene-based HFO refrigerants or mixed refrigerants containing ethylene-based HFO refrigerants, more reliable pressure protection is required. Therefore, in this embodiment, a two-stage pressure protection mechanism is provided, and from the viewpoint of safe shutdown, the threshold pressure of the first protection mechanism is set lower than the threshold pressure of the second protection mechanism.

[0099] Embodiment 7. A refrigeration cycle device according to Embodiment 7 will be described. Figure 18 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 18, a discharge pipe temperature sensor 313 is provided in the discharge pipe of the compressor 100. The discharge pipe temperature sensor 313 is attached to the outer wall surface of the discharge pipe and detects the temperature of the discharge pipe. The temperature of the discharge pipe is a correlated temperature that correlates with the temperature inside the compressor 100. The control device 300 performs temperature protection control based on the temperature detected by the discharge pipe temperature sensor 313. Alternatively, a shell temperature sensor 315 may be provided instead of the discharge pipe temperature sensor 313, and temperature protection control may be performed based on the temperature detected by the shell temperature sensor 315.

[0100] A mechanical thermal protector 314 is provided inside the compressor 100, including the motor 30 and the terminal section of the compressor 100. The thermal protector 314 provides temperature protection for the compressor 100 based on the temperature inside the compressor 100. The above protection control, or temperature protection by the thermal protector 314, corresponds to the first protection mechanism.

[0101] A pressure sensor 316 is provided in the high-pressure piping on the discharge side of the compressor 100. The pressure sensor 316 detects the discharge refrigerant pressure, that is, the pressure inside the compressor 100. The control device 300 performs pressure protection control based on the discharge refrigerant pressure. This pressure protection control corresponds to a second protection mechanism that operates after the first protection mechanism.

[0102] The order of operation of temperature protection and pressure protection may be reversed. That is, pressure protection control using the pressure sensor 316 may correspond to the first protection mechanism, and temperature protection control using the discharge pipe temperature sensor 313 or the shell temperature sensor 315 may correspond to the second protection mechanism.

[0103] If the discharge refrigerant temperature and discharge refrigerant pressure of the compressor 100 rise abnormally due to a malfunction in the refrigeration cycle device 200, the following actions will be taken: If the discharge refrigerant temperature rises abnormally and the temperature detected by the discharge pipe temperature sensor 313 or the shell temperature sensor 315 exceeds a threshold temperature, the control device 300 will stop supplying power to the motor 30. Alternatively, the thermal protector 314 will stop supplying power to the motor 30 if it exceeds a certain threshold temperature.

[0104] On the other hand, if the discharge refrigerant pressure rises abnormally and exceeds the threshold pressure, the control device 300 reduces the rotational speed of the compressor 100 and performs protective control to suppress the rise in discharge refrigerant pressure. Furthermore, if the control device 300 cannot suppress the rise in discharge refrigerant pressure, it performs protective control to stop the operation of the compressor 100.

[0105] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protection control performed by the control device 300 based on the temperature inside the compressor 100 or a correlated temperature correlated with that temperature, or by a thermal protector 314 provided in the compressor 100. The second protection mechanism is realized by protection control performed by the control device 300 based on the pressure inside the compressor 100.

[0106] In this embodiment, temperature protection and pressure protection of the compressor 100 can be performed independently. Therefore, even if one of the protections fails, the rise in temperature and pressure can be suppressed. Consequently, disproportionation reactions can be prevented more reliably.

[0107] Embodiment 8. A refrigeration cycle device according to Embodiment 8 will be described. Figure 19 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 19, a discharge pipe temperature sensor 313 is provided in the discharge pipe of the compressor 100. The discharge pipe temperature sensor 313 is attached to the outer wall surface of the discharge pipe and detects the temperature of the discharge pipe. The temperature of the discharge pipe is a correlated temperature that correlates with the temperature inside the compressor 100. The control device 300 performs protective control based on the temperature detected by the discharge pipe temperature sensor 313. A shell temperature sensor 315 may be provided instead of the discharge pipe temperature sensor 313, and protective control may be performed based on the temperature detected by the shell temperature sensor 315. Alternatively, instead of protective control using the discharge pipe temperature sensor 313 or the shell temperature sensor 315, a thermal protector 314 may be provided inside the compressor 100, such as inside the motor 30 or the terminals of the compressor 100. These temperature protections correspond to the first protection mechanism.

[0108] The compressor 100 is connected to the power supply 320 via a current protector 311, an inverter 301, and an overcurrent circuit breaker 312. Power is supplied from the power supply 320 to the compressor 100, passing through the overcurrent circuit breaker 312, the inverter 301, and the current protector 311 in that order. The current protector 311 and the overcurrent circuit breaker 312 are mechanical current protection mechanisms installed in the power path between the power supply 320 and the compressor 100. Instead of mechanical current protection mechanisms, the control device 300 may perform protective control to reduce the output of the compressor 100 or stop the compressor 100 when the motor current exceeds a certain threshold. These current protections correspond to a second protection mechanism.

[0109] The operating order of temperature protection and current protection may be reversed. That is, the current protection described above may correspond to the first protection mechanism, and the temperature protection described above may correspond to the second protection mechanism.

[0110] If a malfunction occurs in the refrigeration cycle device 200, causing an abnormal rise in the discharge refrigerant temperature of the compressor 100 and the current flowing to the motor 30, the following actions will be taken: If the discharge refrigerant temperature rises abnormally and the temperature detected by the discharge pipe temperature sensor 313 or the shell temperature sensor 315 exceeds a threshold temperature, the control device 300 will stop the power supply to the motor 30. Alternatively, the thermal protector 314 will stop the power supply to the motor 30 if it exceeds a certain threshold temperature.

[0111] On the other hand, if the current value flowing to the motor 30 rises abnormally and exceeds the threshold current value of the current protector 311, the compressor 100 is forcibly stopped by disconnecting the bimetal of the current protector 311. Alternatively, if the current value exceeds the threshold current value of the overcurrent circuit breaker 312, the compressor 100 is forcibly stopped by overcurrent interruption. Alternatively, if the current value exceeds the threshold current value of the protection control, the compressor 100 is stopped by the protection control of the control device 300.

[0112] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protection control performed by the control device 300 based on the temperature inside the compressor 100 or a correlated temperature correlated with that temperature. Alternatively, the first protection mechanism is a thermal protector 314 provided in the compressor 100. The second protection mechanism is a current protector 311 provided in the compressor 100. Alternatively, the first protection mechanism is an overcurrent circuit breaker 312 provided in the power path between the power supply 320 of the refrigeration cycle device 200 and the compressor 100. Alternatively, the first protection mechanism is realized by protection control performed by the control device 300 based on the current value.

[0113] In this embodiment, temperature protection and current protection of the compressor 100 can be performed independently. Therefore, even if one of the protections fails, the rise in temperature and current values ​​can be suppressed. Consequently, disproportionation reactions can be prevented more reliably.

[0114] Embodiment 9. A refrigeration cycle device according to Embodiment 9 will be described. Figure 20 is a block diagram showing the schematic configuration of the refrigeration cycle device according to this embodiment. As shown in Figure 20, a pressure sensor 316 is provided in the high-pressure piping on the discharge side of the compressor 100. The pressure sensor 316 detects the discharge refrigerant pressure, that is, the pressure inside the compressor 100. The control device 300 performs pressure protection control based on the discharge refrigerant pressure. This pressure protection control corresponds to the first protection mechanism.

[0115] The compressor 100 is connected to the power supply 320 via a current protector 311, an inverter 301, and an overcurrent circuit breaker 312. Power is supplied from the power supply 320 to the compressor 100, passing through the overcurrent circuit breaker 312, the inverter 301, and the current protector 311 in that order. The current protector 311 and the overcurrent circuit breaker 312 are mechanical current protection mechanisms installed in the power path between the power supply 320 and the compressor 100. These current protections correspond to the second protection mechanism.

[0116] The operating order of pressure protection and current protection may be reversed. That is, the current protection described above may correspond to the first protection mechanism, and the pressure protection described above may correspond to the second protection mechanism.

[0117] If a malfunction occurs in the refrigeration cycle device 200, causing an abnormal increase in the discharge refrigerant pressure of the compressor 100 and the current flowing to the motor 30, the control device 300 will operate as follows: If the discharge refrigerant pressure increases abnormally and exceeds the threshold pressure, the control device 300 will reduce the rotational speed of the compressor 100 and perform protective control to suppress the increase in discharge refrigerant pressure. Furthermore, if the control device 300 is unable to suppress the increase in discharge refrigerant pressure, it will perform protective control to stop the operation of the compressor 100.

[0118] On the other hand, if the current value flowing to the motor 30 rises abnormally and exceeds the threshold current value of the current protector 311, the compressor 100 is forcibly stopped by disconnecting the bimetal of the current protector 311. Alternatively, if the current value exceeds the threshold current value of the overcurrent circuit breaker 312, the compressor 100 is forcibly stopped by overcurrent interruption. Alternatively, if the current value exceeds the threshold current value of the protection control, the compressor 100 is stopped by the protection control of the control device 300.

[0119] As described above, the refrigeration cycle device 200 according to this embodiment further includes a control device 300 that controls the refrigerant circuit 201. The first protection mechanism is realized by protection control performed by the control device 300 based on the pressure in the compressor 100. The second protection mechanism is a current protector 311 provided in the compressor 100. Alternatively, the second protection mechanism is an overcurrent circuit breaker 312 provided in the power path between the power supply 320 of the refrigeration cycle device 200 and the compressor 100. Alternatively, the second protection mechanism is realized by protection control performed by the control device 300 based on the current value flowing through the motor 30.

[0120] In this embodiment, pressure protection and current protection of the compressor 100 can be performed independently. Therefore, even if one of the protections fails, the rise in pressure and current values ​​can be suppressed. Consequently, disproportionation reactions can be prevented more reliably.

[0121] 10 Sealed container, 11 Body, 12 Top lid, 13 Bottom lid, 14 Refrigerant oil, 20 Compression mechanism, 21 Rotating shaft, 21a Main shaft, 21b Eccentric shaft, 21c Sub-shaft, 22 Rolling piston, 23 Cylinder, 23a Cylinder chamber, 23b Intake port, 24 Upper bearing, 25 Lower bearing, 27 Discharge muffler, 30 Motor, 31 Rotor, 32 Stator, 32a Stator core, 32b Stator winding, 100 Compressor, 101 Intake muffler, 101a Intake connecting pipe, 102 Discharge pipe, 103 Four-way valve, 104 Outdoor heat exchanger, 105 Throttle device, 106 Indoor heat exchanger, 200 Refrigeration cycle device, 201 Refrigerant circuit, 300 Control device, 301 Inverter, 310 Protection mechanism, 311 current protector, 312 overcurrent circuit breaker, 313 discharge pipe temperature sensor, 314 thermal protector, 315 shell temperature sensor, 316 pressure sensor, 317 pressure switch, 320 power supply.

Claims

1. A refrigerant circuit including a compressor having a compression mechanism and a motor that drives the compression mechanism; a refrigerant circulating through the refrigerant circuit; and a protective mechanism that operates based on the temperature inside the compressor, the pressure inside the compressor, or the current value flowing to the motor, and suppresses the rise of at least one of the temperature and the pressure, wherein the refrigerant is an ethylene-based HFO refrigerant or a mixed refrigerant containing an ethylene-based HFO refrigerant, and the stroke volume of the compression mechanism is V [cm ３ A refrigeration cycle device in which, when the rated output of the motor is Q [W], Q / V is 25 or more and 300 or less.

2. The refrigeration cycle apparatus according to claim 1, wherein the protection mechanism includes a first protection mechanism and a second protection mechanism that operates after the first protection mechanism.

3. The refrigeration cycle apparatus according to claim 2, wherein the first protection mechanism is a current protector attached to the compressor, and the second protection mechanism is an overcurrent circuit breaker provided in the power path between the power supply of the refrigeration cycle apparatus and the compressor.

4. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the current value, and the second protection mechanism is a current protector provided on the compressor, or an overcurrent circuit breaker provided in the power path between the power supply of the refrigeration cycle apparatus and the compressor.

5. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the temperature or a correlated temperature correlated with the temperature, and the second protection mechanism is a thermal protector provided on the compressor.

6. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is a thermal protector provided on the compressor, and the second protection mechanism is realized by protection control performed by the control device based on the temperature or a correlated temperature correlated with the temperature.

7. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the pressure, and the second protection mechanism is a pressure switch that operates based on the pressure.

8. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the temperature or a correlated temperature, or is a thermal protector provided on the compressor, and the second protection mechanism is realized by protection control performed by the control device based on the pressure.

9. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the temperature or a correlated temperature correlated with the temperature, or is a thermal protector provided on the compressor, and the second protection mechanism is realized by current protector provided on the compressor, an overcurrent circuit breaker provided in the power path between the power supply of the refrigeration cycle apparatus and the compressor, or by protection control performed by the control device based on the current value.

10. The refrigeration cycle apparatus according to claim 2, further comprising a control device for controlling the refrigerant circuit, wherein the first protection mechanism is realized by protection control performed by the control device based on the pressure, and the second protection mechanism is realized by a current protector provided on the compressor, an overcurrent circuit breaker provided in the power path between the power supply of the refrigeration cycle apparatus and the compressor, or protection control performed by the control device based on the current value.

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