GB2599514A

GB2599514A - Refrigeration cycle system

Info

Publication number: GB2599514A
Application number: GB2116301.9A
Authority: GB
Inventors: Hirosaki Hiroki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-07-17
Filing date: 2019-07-17
Publication date: 2022-04-06
Anticipated expiration: 2039-07-17
Also published as: WO2021009881A1; GB2599514B; JP7259962B2; JPWO2021009881A1; GB202116301D0

Abstract

This refrigeration cycle system comprises: a detection means for detecting a relevant physical quantity, which is a physical quantity relating to the state of a refrigerant circuit; and a control means for executing a circuit state determination mode after starting a compressor and before starting a normal operation mode in which the refrigeration cycle operation by the refrigerant circuit is performed. The control means switches from the circuit state determination mode to the normal operation mode if a first comparison value CQ1 obtained by comparing a first detection value PQ1, which is the value of the relevant physical quantity at the point in time at which a first time has elapsed from the start time of the circuit state determination mode, and a second detection value PQ2, which is the value of the relevant physical quantity at the point in time at which a second time longer than the first time has elapsed from the start time, is smaller than a normal determination value A. Otherwise, the circuit state determination mode is continued.

Description

Description Title

REFRIGERATION CYCLE SYSTEM

Field

[0001] The present invention relates to a refrigeration cycle system

Background

[0002] In Patent literature 1 below, as a technique for determining an anomaly in a refrigerant circuit of a heat pump water heater, a technique is disclosed that is provided with a current value detection means for detecting a value of a current flowing through a compressor and stops the operation of the compressor if the value of the current detected by the current value detection means exceeds a predetermined value within a predetermined time after the compressor is started.

Citation List Patent Literature [0003] [PTL 11 JP 2010-071603 A

Summary

Technical Problem [0004] In the conventional system described above, even if the refrigerant circuit is normal, a normal operation cannot be started because it is not possible to determine that the refrigerant circuit is normal until the above-described predetermined time has elapsed In addition, there are variations in characteristics among detectors due to individual differences within the normal range Therefore, in the conventional system described above, there are some errors in the measured current values Further, among elements of the refrigerant circuit (for example, decompressors), there are also variations in characteristics due to individual differences within the normal range In the conventional system described above, in order to prevent erroneous determination caused by such variations due to individual differences within the normal range, it is necessary to set the predetermined time to be long. As a result, even if the refrigerant circuit is normal, it takes a long time from the start of the compressor to the start of the normal operation, which is accompanied by a problem that an increased power consumption is caused.

[0005] An object of the present invention, which has been made to solve the problem as described above, is to provide a refrigeration cycle system that is advantageous in shortening the time to start the normal operation after the start of the compressor. Solution to Problem [0006] A refrigeration cycle system according to the present invention includes: a refrigerant circuit including a compressor for compressing refrigerant, a cooler for cooling the refrigerant compressed by the compressor, a decompressor for decompressing the refrigerant that has passed through the cooler, and an evaporator for evaporating the refrigerant that has passed through the decompressor; detection means for detecting a related physical quantity that is a physical quantity related to a state of the refrigerant circuit; and control means for executing a circuit state determination mode after starting -j -the compressor and before starting a normal operation mode in which a refrigeration cycle operation using the refrigerant circuit is performed. The control means is configured to switch from the circuit state determination mode to the normal operation mode if a first comparison value obtained by comparing a first detection value, which is a value of the related physical quantity at a point of time at which a first time has elapsed from a starting point of time of the circuit state determination mode, with a second detection value, which is a value of the related physical quantity at a point of time at which a second time longer than the first time has elapsed from the starting point of time, is smaller as compared with a normality determination value, or continue the circuit state determination mode if not Advantageous Effects of Invention [0007] According to the present invention, it is possible to provide a refrigeration cycle system that is advantageous in shortening the time to start the normal operation after the start of the compressor.

Brief Description of Drawings

[0008] Fig. 1 is a diagram showing a refrigeration cycle system according to a first embodiment.

Fig. 2 is a flowchart showing an example of processing executed by a control unit in a circuit state determination mode.

Fig. 3 is a diagram showing an example of a time-dependent change in a related physical quantity after a start of a compressor. 4 -

Fig 4 is a diagram showing an example of a time-dependent change in a related physical quantity after the start of the compressor when an evaporator inlet temperature is used as the related physical quantity.

Description of Embodiments

[0009] Hereinafter, embodiments will be described with reference to the drawings. The common or corresponding elements in the drawings are designated by the same reference numerals to simplify or omit the common descriptions.

[0010] First embodiment Fig. 1 is a diagram showing a refrigeration cycle system according to a first embodiment. As shown in Fig. 1, a refrigeration cycle system 1 is provided with a refrigerant circuit 2, a measurement unit 7, and a control unit 8 The refrigerant circuit 2 is provided with a compressor 3 that compresses a refrigerant, a cooler 4 that cools a high-pressure refrigerant compressed by the compressor 3, a decompressor 5 that decompresses the high-pressure refrigerant that has passed through the cooler 4, and an evaporator 6 that evaporates a low-pressure refrigerant that has been decompressed by the decompressor 5. The compressor 3, the cooler 4, the decompressor 5, and the evaporator 6 are connected via a refrigerant pipe to form an annular circuit. A low-pressure refrigerant gas flowing out of the evaporator 6 is sucked into the compressor 3 and circulates in the refrigerant circuit 2 again. The refrigerant circuit 2 is operated by electric power.

[0011] -5 -The refrigerant sealed in the refrigerant circuit 2 is not particularly limited, but may be, for example, any one of carbon dioxide, ammonia, propane, isobutane, fluorocarbon such as HFC, HFO-1123, and HF0-1234yf [0012] The cooler 4 corresponds to a heat exchanger that exchanges heat between the high-pressure refrigerant discharged from the compressor 3 and a first fluid having a temperature lower than that of the high-pressure refrigerant In the cooler 4, the temperature of the first fluid increases by being heated by the high-pressure refrigerant. The first fluid may be, for example, a liquid such as water or any other liquid heat medium, or a gas such as outdoor air or indoor air. The refrigeration cycle system 1 may be provided with a first fluid actuator (not shown), for example, such as a pump or a blower, for allowing the first fluid to flow to the cooler 4.

[0013] The decompressor 5 expands the high-pressure refrigerant into the low-pressure refrigerant. The decompressor 5 may be an expansion valve that is adjustable in an opening degree to a refrigerant passage. The low-pressure refrigerant that has passed through the decompressor 5 is in a gas-liquid two-phase state.

[0014] The evaporator 6 corresponds to a heat exchanger that exchanges heat between the low-pressure refrigerant decompressed by the decompressor 5 and a second fluid having a temperature higher than that of the low-pressure refrigerant. The refrigerant in the evaporator 6 evaporates by absorbing the heat of the second fluid. The second fluid may be, for example, a gas such as outdoor air or indoor air, or a liquid such as water or any other liquid heat medium. The refrigeration cycle system 1 may be provided with a second fluid actuator (not shown), for example, such as a blower or a pump, for allowing the second fluid to flow to the evaporator 6.

[0015] The refrigeration cycle system 1 may be used for the purpose of heating the first fluid by the cooler 4, or may be used for the purpose of cooling the second fluid by the evaporator 6 For example, the refrigeration cycle system 1 may be used in at least one of a heat pump hot water supply system, a heat pump heating system, and an air conditioning system.

[0016] A physical quantity related to a state of the refrigerant circuit 2 is hereinafter referred to as the "related physical quantity". The measurement unit 7 has a detector for detecting the related physical quantity. The detector corresponds to a detection means for detecting the related physical quantity. The measurement unit 7 can measure a value of the related physical quantity by using the detector. The measurement unit 7 detects at least one kind of related physical quantities The measurement unit 7 in the present embodiment detects a compressor current, which is a current flowing through an electric motor included in the compressor 3, as the related physical quantity. The compressor current is correlated with a drive load of the compressor 3. The higher the pressure on the high pressure side of the refrigerant circuit 2, the higher the drive load of the compressor 3 tends to be. As a result, the compressor current also tends to be higher. Therefore, it can be said that the compressor current is a kind of related physical quantity. [0017] The measurement unit 7 may detect only a current supplied to the compressor 3 as the compressor current, or may detect a current including the current supplied to the compressor 3 and a current supplied to other devices (for example, the first fluid actuator and the second fluid actuator) as the compressor current. Since the current supplied to the other devices is smaller as compared with the current supplied to the compressor 3, the current supplied to the other devices can be substantially ignored. In the case of the alternating current, the measurement unit 7 may detect an effective value of the current as the compressor current.

[0018] The control unit 8 corresponds to a control means for controlling an operation of the refrigeration cycle system 1. Each actuator and each sensor included in the refrigeration cycle system 1 are electrically connected to the control unit 8. The control unit 8 has a timer function for managing the time. The control unit 8 may be able to communicate with a user interface device (not shown).

[0019] Each function of the control unit 8 may be implemented by processing circuitry. The processing circuitry of the control unit 8 may be provided with an at least one processor 8a and an at least one memory 8b. The at least one processor 8a may implement each function of the control unit 8 by reading and executing a program stored in the at least one memory 8b. Each processing circuitry of the control unit 8 may be provided with an at least one dedicated hardware The configuration is not limited to the configuration in which the operation is controlled by the single control unit 8 as in the illustrated example, and the operation may be controlled by the cooperation of a plurality of control devices.

[0020] The control unit 8 controls an operation of the compressor 3 and the decompressor 5 The control unit 8 may control an operating speed of the compressor 3 in such a mariner as to be variable, for example, by inverter control. The control unit 8 may adjust an opening degree of the decompressor 5. Further, the control unit 8 may control an operating speed of at least one of the first fluid actuator and the second fluid actuator in such a manner as to be variable, for example, by inverter control.

[0021] The control unit 8 can execute a normal operation mode in which the refrigeration cycle operation using the refrigerant circuit 2 is performed. At the time of the normal operation mode, the following may be performed. The control unit 8 may control the operating speed of the compressor 3 in response to a heating capacity or a cooling capacity to be targeted. The control unit 8 may adjust the opening degree of the decompressor 5 in response to a temperature or a pressure of the refrigerant discharged from the compressor 3. The control unit 8 may control the operating speed of the first fluid actuator in response to at least one of a temperature of the first fluid flowing into the cooler 4 and a temperature of the first fluid flowing out of the cooler 4. The control unit 8 may control the operating speed of the second fluid actuator in response to at least one of a temperature of the second fluid flowing into the evaporator 6 and a temperature of the second fluid flowing out of the evaporator 6.

[0022] The control unit 8 executes a circuit state determination mode for determining a state of the refrigerant circuit 2 after starting the compressor 3 and before starting the normal operation mode A starting point of time of the circuit state determination mode is hereinafter referred to as the "starting point of time". As the starting point of time, the -9 -control unit 8 may use a point of time at which the compressor 3 is started. In the circuit state determination mode, it is desirable that the control unit 8 maintains the operating speed of the compressor 3 at a predetermined constant speed. With this, the state of the refrigerant circuit 2 can be determined more accurately. Further, in the circuit state determination mode, it is desirable that the control unit 8 maintains the operating speed of the first fluid actuator at a predetermined constant speed or stops the first fluid actuator, and maintains the operating speed of the second fluid actuator at a predetermined constant speed or stop the second fluid actuator. This makes it possible to determine the state of the refrigerant circuit 2 more accurately.

[0023] Fig. 2 is a flowchart showing an example of processing executed by the control unit 8 in the circuit state determination mode. Fig. 3 is a diagram showing an example of a time-dependent change in the related physical quantity after the start of the compressor 3. In the present embodiment, the time-dependent change in the related physical quantity shown in Fig. 3 corresponds to a time-dependent change in the compressor current. In Fig. 3, time tO corresponds to the starting point of time.

[0024] In the present embodiment, the control unit 8 switches from the circuit state determination mode to the normal operation mode if a first comparison value CQ1 obtained by comparing a first detection value PQ1, which is a value of the compressor current at a point of time at which a predetermined first time has elapsed from the starting point of time, with a second detection value PQ2, which is a value of the compressor current at a point of time at which a predetermined second time longer than the first time has elapsed from the starting point of time is smaller as compared with a predetermined -10 -normality determination value A Otherwise, the circuit state determination mode is continued. In Fig. 3, a time from time tO to time t1 corresponds to the first time, and a time from time tO to time t2 corresponds to the second time.

[0025] The first comparison value CQ1 may be a difference between the first detection value PQ1 and the second detection value PQ2 In this case, the control unit 8 may calculate the first comparison value CQ1 by, for example, the following equation CQ1 = PQ2 -PQ1 (1) [0026] Alternatively, the first comparison value CQ1 may be an increase/decrease rate between the first detection value PQ1 and the second detection value PQ2 In this case, the control unit 8 may calculate the first comparison value CQ1 by, for example, the following equation CQ1 = PQ2 / PQ1 -11 (2) [0027] As shown in Fig. 3, after the start of the compressor 3, the compressor current gradually increases When the element of the refrigerant circuit 2 (for example, the decompressor 5) is normal, the operation of the element maintains an inside of the refrigerant circuit 2 at an appropriate pressure As a result, around the time ti at which the first time has elapses from the starting point of time, the degree of increase in the compressor current slows down and the compressor current converges within a substantially constant range. In such a case, since the second detection value PQ2 is close to the first detection value PQ1, the first comparison value CQ1 is smaller as compared with the normality determination value A. Therefore, if the first comparison value CQ1 is smaller as compared with the normality determination value A, it can be determined that the refrigerant circuit 2 is clearly normal. Then, there is no problem in starting the normal operation mode.

[0028] While the circuit state determination mode is being executed, the heating capacity or the cooling capacity to be targeted may not be obtained, the first fluid may not be sufficiently heated, or the second fluid may not be sufficiently cooled For this reason, it is not preferable that the time to shift from the circuit state determination mode to the normal operation mode is delayed.

[0029] In the present embodiment, by comparing the first comparison value CQ1 with the normality determination value A, if the refrigerant circuit 2 is clearly normal, that fact can be determined at an early point Therefore, there is an advantage that shift to the normal operation mode can be made at an early point.

[0030] In contrast to this, if there is an anomaly in the element of the refrigerant circuit 2, the pressure inside the refrigerant circuit 2 is not appropriate For example, if there is an anomaly in which a refrigerant flow path of the decompressor 5 is blocked, the pressure on the downstream side of the compressor 3 increases in an abnormal manner. As a result, the drive load of the compressor 3 becomes excessive, the degree of increase in the compressor current does not slow down even after the first time has elapsed from the starting point of time, and the compressor current does not converge within a substantially constant range. In such a case, since the difference between the second detection value PQ2 and the first detection value PQ1 is large, the first comparison value -12 -CQ1 is larger as compared with the normality determination value A. In the present embodiment, if the first comparison value CQ1 is equal to or larger than the normality determination value A, the circuit state determination mode is continued. This can reliably prevent the normal operation mode from being started at a point of time at which it is not yet possible to confirm that the refrigerant circuit 2 is normal.

[0031] In general, among the detectors that detect the related physical quantity such as the compressor current, there are variations in characteristics due to individual differences. For this reason, there are some errors in the values of the related physical quantity measured by the measurement unit 7. Assuming that the measured value itself of the related physical quantity is compared with the determination value, there is a possibility that erroneous determination is made by the influence of the error of the measured value caused by the variations of the detectors. In contrast to this, in the present embodiment, an error included in the first detection value PQ1 and an error included in the second detection value PQ2 cancel each other out, which makes the first comparison value CQ not easily affected by the error. For this reason, in the present embodiment, by comparing the first comparison value CQ1 with the normality determination value A, the influence of the error can be reliably reduced. As a result, the erroneous determination can be reliably prevented.

[0032] In the following description, with respect to the element of the refrigerant circuit 2, among a plurality of normal products Inspected in an inspection of a characteristic of the element alone, an individual having a statistical median value of the characteristic is referred to as the "median product". For example, a decompressor 5 which is the -13 -median product corresponds to an individual in which the flow rate characteristic thereof is a statistical median value among the plurality of normal products. Further, among the plurality of normal products, an individual belonging to the lower limit of the statistical distribution of the above characteristic is referred to as the "lower limit product". For example, a decompressor S which is the lower limit product is an individual in which the refrigerant flow rate is lower as compared with that of the median product of the decompressor 5 under the same setting The lower limit product is included in the normal products Therefore, the refrigerant circuit 2 in which the lower limit product is used is included in the normal range.

[0033] Fig. 3 shows a graph of the related physical quantity when the median product is used and a graph of the related physical quantity when the lower limit product is used. In the case of the lower limit product, since the refrigerant flow rate passing through the decompressor 5 is lower than that of the median product, the pressure on the downstream side of the compressor 3 is higher than that of the median product. As a result, the compressor current in the case of the lower limit product is higher than the compressor current in the case of the median product. Further, in the case of the lower limit product, the time at which the degree of increase in the compressor current slows down is later than the time at which the degree of increase in the compressor current slows down in the case of the median product. As a result, in the case of the lower limit product, although the refrigerant circuit 2 is normal, the difference between the second detection value PQ2 and the first detection value PQ I is large, which makes the first comparison value CQ1 larger as compared with the normality determination value A. [0034] -14 -In the present embodiment, the respective values of the first time, the second time, and the normality determination value A are defined as values that can determine that the refrigerant circuit 2 is normal when the median product is used. For example, the first time is set to be a time such that the related physical quantity converges within substantially constant range when the median product is used. In the present embodiment, if the refrigerant circuit 2 is clearly normal as in the case in which the median product is used, that fact can be determined at an earlier point As a result, shift to the normal operation mode can be made at an earlier point.

[0035] If the circuit state determination mode is continued even after the second time has elapsed, that is, if the first comparison value CQ1 is not smaller as compared with the normality determination value A, the control unit 8 may perform the following. The control unit 8 switches from the circuit state determination mode to the normal operation mode if a second comparison value CQ2 obtained by comparing a third detection value PQ3, which is a value of the compressor current at a point of time at which a third time longer than the second time has elapsed from the starting point of time, with a fourth detection value PQ4, which is a value of the compressor current at a point of time at which a fourth time longer than the third time has elapsed from the starting point of time, is smaller as compared with a predetermined anomaly determination value B [0036] The second comparison value CQ2 may be a difference between the third detection value PQ3 and the fourth detection value PQ4 In this case, the control unit 8 may calculate the second comparison value CQ2 by, for example, the following equation.

CQ2 = PQ4 -PQ3 (3) -15 -[0037] Alternatively, the first comparison value CQ I may be an increase/decrease rate between the third detection value PQ3 and the fourth detection value PQ4 In this case, the control unit 8 may calculate the second comparison value CQ2 by, for example, the following equation.

CQ2 = PQ4 / PQ3 -11 (4) [0038] In the present embodiment, an error included in the third detection value PQ3 and an error included in the fourth detection value PQ4 cancel each other out, which makes the second comparison value CQ2 not easily affected by the error of the measured value by the measurement unit 7. For this reason, in the present embodiment, by comparing the second comparison value CQ2 with the anomaly determination value B, the influence of the error can be reliably reduced As a result, the erroneous determination can be reliably prevented.

[0039] As shown in Fig. 3, when the lower limit product is used, around the time t3 at which the third time has elapses from the starting point of time, the degree of increase in the compressor current slows down and the compressor current converges within a substantially constant range In such a case, since the fourth detection value PQ4 is close to the third detection value PQ3, the second comparison value CQ2 is smaller as compared with the anomaly determination value B. Therefore, if the comparison value CQ2 is smaller as compared with the anomaly determination value B, it can be determined that the refrigerant circuit 2 is normal Then, there is no problem in starting the normal operation mode.

-16 -[0040] In contrast to this, if there is an anomaly in the element of the refrigerant circuit 2, for example, if there is an anomaly in which the refrigerant flow path of the decompressor 5 is blocked, the degree of increase in the compressor current does not slow down even after the third time has elapsed from the starting point of time, and the compressor current does not converge within a substantially constant range. In such a case, since the fourth detection value PQ4 has a large difference from the third detection value PQ3, the second comparison value CQ2 is not smaller as compared with the anomaly determination value B. When the second comparison value CQ2 is not smaller as compared with the anomaly determination value B, the control unit 8 stops the compressor 3. With this, continued operation of the compressor 3 while the refrigerant circuit 2 is in an abnormal state can be reliably prevented. As a result, the refrigerant circuit 2 can be protected.

[0041] In the present embodiment, the respective values of the third time, the fourth time, and the anomaly determination value B are defined as values that can determine that the refrigerant circuit 2 is normal when the lower limit product is used. For example, the third time is set to be a time such that the related physical quantity converges within a substantially constant range when the lower limit product is used In the present embodiment, when the lower limit product is used, it is possible to reliably prevent the erroneous determination that the refrigerant circuit 2 is abnormal.

[0042] The present embodiment is more advantageous in starting the normal operation mode at an early point by performing the normality determination using the first -17 -comparison value CQ1 and the normality determination value A, before the anomaly determination using the second comparison value CQ2 and the anomaly determination value B. [0043] Hereinafter, an example of processing of the circuit state determination mode will be described with reference to a flowchart of Fig. 2. After the start of the compressor 3, the control unit 8 starts the circuit state determination mode. As step SI, the control unit 8 stores the first detection value PQ1 measured by the measurement unit 7 at the point of time ti at which only the first time has elapsed from the starting point of time. Next, as step S2, the control unit 8 stores the second detection value PQ2 measured by the measurement unit 7 at the point of time t2 at which only the second time has elapsed from the starting point of time. Next, as step S3, the control unit 8 determines whether or not the first comparison value CQ1 is smaller than the normality determination value A. If the first comparison value CQ1 is smaller than the normality determination value A, the control unit 8 determines, as step S7, that the refrigerant circuit 2 is normal, ends the circuit state determination mode, and starts the normal operation mode.

[0044] In contrast to this, if the first comparison value CQ1 is equal to or larger than the normality determination value A, the control unit 8 continues the circuit state determination mode. In this case, as step S4, the control unit 8 stores the third detection value PQ3 measured by the measurement unit 7 at the point of time t3 at which only the third time has elapsed from the starting point of time Next, as step S5. the control unit 8 stores the fourth detection value PQ4 measured by the measurement unit 7 at the point of time t4 at which only the fourth time has elapsed from the starting point of time.

-18 -Next, as step S6, the control unit 8 determines whether or not the second comparison value CQ2 is smaller than the anomaly determination value B. If the second comparison value CQ2 is smaller than the anomaly determination value B, the control unit 8 determines, as step S8, that the refrigerant circuit 2 is normal, ends the circuit state determination mode, and starts the normal operation mode. In contrast to this, if the second comparison value CQ2 is equal to or larger than the anomaly determination value B, the control unit 8 determines, as step 59, that the refrigerant circuit 2 is abnormal, stops the compressor 3, and ends the operation of the refrigerant circuit 2.

[0045] As described above, in the present embodiment, the normal operation mode can be started if the anomaly in the refrigerant circuit 2 is not detected. Further, if the anomaly in the refrigerant circuit 2 is detected, the operation of the refrigerant circuit 2 is stopped, which can reliably prevent an occurrence of a fa lure [0046] Second Embodiment Next, a second embodiment will be described, but the differences from the first embodiment described above will be mainly described, and the description of the same or corresponding parts will be simplified or omitted.

[0047] The second embodiment is different from the first embodiment in that a compressor temperature is used as the related physical quantity instead of the compressor current. The compressor temperature is a temperature of the compressor 3. The measurement unit 7 has a detector for detecting the compressor temperature. The compressor temperature may be, for example, a temperature of a shell included in the -19 -compressor 3. In the compressor 3 of the high-pressure shell type, the inside of the shell is filled with the high-pressure refrigerant before being discharged from the compressor 3. The higher the pressure on the high-pressure side of the refrigerant circuit 2, the higher the drive load of the compressor 3 tends to be. Then, the higher the drive load of the compressor 3 the higher the compressor temperature tends to be. Therefore, it can be said that the compressor temperature is a kind of related physical quantity.

[0048] The time-dependent change in the compressor temperature after the start of the compressor 3 shows the same tendency as that of the graph of Fig. 3. In the second embodiment, the control unit 8 executes the same processing as that of the first embodiment by using a detection value of the compressor temperature instead of the detection value of the compressor current in the first embodiment. Thereby, the same effect as that of the first embodiment can be obtained [0049] Third Embodiment Next, a third embodiment will be described, but the differences from the first embodiment described above will be mainly described, and the description of the same or corresponding parts will be simplified or omitted.

[0050] The third embodiment is different from the first embodiment in that a discharged refrigerant temperature is used as the related physical quantity instead of the compressor current. The discharged refrigerant temperature is a temperature of the refrigerant discharged from the compressor 3 The measurement unit 7 has a detector for detecting the temperature of the discharged refrigerant.

-20 -[0051] The time-dependent change in the discharged refrigerant temperature after the start of the compressor 3 shows the same tendency as that of the graph of Fig. 3. In the third embodiment, the control unit 8 executes the same processing as that of the first embodiment by using a detection value of the discharged refrigerant temperature instead of the detection value of the compressor current in the first embodiment. Thereby, the same effect as that of the first embodiment can be obtained [0052] Fourth Embodiment Next, a fourth embodiment will be described, but the differences from the first embodiment described above will be mainly described, and the description of the same or corresponding parts will be simplified or omitted.

[0053] The fourth embodiment is different from the first embodiment in that an evaporator inlet temperature is used as the related physical quantity instead of the compressor current The evaporator inlet temperature is a temperature of the refrigerant flowing into the evaporator 6. The measurement unit 7 has a detector for detecting the evaporator inlet temperature [0054] Fig. 4 is a diagram showing an example of the time-dependent change in the related physical quantity after the start of the compressor 3 when the evaporator inlet temperature is used as the related physical quantity. Fig. 4 shows a graph of the related physical quantity when a decompressor 5 which is the median product is used, a graph of the related physical quantity when a decompressor 5 which is the lower limit product is -21 -used, and a graph of the related physical quantity when a decompressor 5 which is an abnormal product is used. The refrigerant flow rate of the decompressor 5 is in the order of the median product > the lower limit product > the abnormal product.

Therefore, the decompression amount of the decompressor 5 under the same setting is in the order of the median product < the lower limit product < the abnormal product, and the evaporator inlet temperatures show the time-dependent change as shown in Fig. 4 due to the differences in the refrigerant pressures on the low-pressure side In the fourth embodiment, the control unit 8 executes the same processing as that of the first embodiment by using a detection value of the evaporator inlet temperature instead of the detection value of the compressor current in the first embodiment. Thereby, the same effect as that of the first embodiment can be obtained [0055] Fifth Embodiment Next, a fifth embodiment will be described, but the differences from the first embodiment described above will be mainly described, and the description of the same or corresponding parts will be simplified or omitted.

[0056] The fifth embodiment is different from the first embodiment in that an evaporator outlet temperature is used as the related physical quantity instead of the compressor current. The evaporator outlet temperature is a temperature of the refrigerant flowing out of the evaporator 6 The measurement unit 7 has a detector for detecting the evaporator outlet temperature.

[0057] -22 -The time-dependent change in the evaporator outlet temperature after the start of the compressor 3 shows the same tendency as that of the graph of Fig. 4. In the fifth embodiment, the control unit 8 executes the same processing as that of the first embodiment by using a detection value of the evaporator outlet temperature instead of the detection value of the compressor current in the first embodiment. Thereby, the same effect as that of the first embodiment can be obtained.

[0058] It should be noted that the measurement unit 7 may detect, as the related physical quantities, two or more of the compressor current, the compressor temperature, the discharged refrigerant temperature, the evaporator inlet temperature, and the evaporator outlet temperature described in each of the above-described embodiments.

Reference Signs List [0059] 1 refrigeration cycle system 2 refrigerant circuit 3 compressor 4 cooler decompressor 6 evaporator 7 measurement unit 8 control unit 8a processor 8b memory

Claims

-23 -Claims [Claim 1] A refrigeration cycle system, comprising: a refrigerant circuit including a compressor for compressing refrigerant, a cooler for cooling the refrigerant compressed by the compressor, a decompressor for decompressing the refrigerant that has passed through the cooler, and an evaporator for evaporating the refrigerant that has passed through the decompressor; detection means for detecting a related physical quantity that is a physical quantity related to a state of the refrigerant circuit and control means for executing a circuit state determination mode after starting the compressor and before starting a normal operation mode in which a refrigeration cycle operation using the refrigerant circuit is performed, wherein the control means is configured to switch from the circuit state determination mode to the normal operation mode if a first comparison value obtained by comparing a first detection value, which is a value of the related physical quantity at a point of time at which a first time has elapsed from a starting point of time of the circuit state determination mode, with a second detection value, which is a value of the related physical quantity at a point of time at which a second time longer than the first time has elapsed from the starting point of time, is smaller as compared with a normality determination value, or continue the circuit state determination mode if not.[Claim 2] The refrigeration cycle system according to claim 1, wherein the control means is configured to, when the circuit state determination mode is continued even after the second time has elapsed, switch from the circuit state determination mode to the normal -24 -operation mode if a second comparison value obtained by comparing a third detection value, which is a value of the related physical quantity at a point of time at which a third time longer than the second time has elapsed from the starting point of time, with a fourth detection value, which is a value of the related physical quantity at a point of time at which a fourth time longer than the third time has elapsed from the starting point of time, is smaller as compared with an anomaly determination value.[Claim 3] The refrigeration cycle system according to claim 2, wherein the control means is configured to stop the compressor if the second comparison value is not smaller as compared with the anomaly determination value.[Claim 4] The refrigeration cycle system according to any one of claims 1 to 3, wherein the detection means is configured to detect, as the related physical quantity, at least one of a current flowing through the compressor, a temperature of the compressor, a discharged refrigerant temperature that is a temperature of the refrigerant discharged from the compressor, an evaporator inlet temperature that is a temperature of the refrigerant flowing into the evaporator, and an evaporator outlet temperature that is a temperature of the refrigerant flowing out of the evaporator.[Claim 5] The refrigeration cycle system according to any one of claims 1 to 4, wherein the first comparison value is a difference or an increase/decrease rate between the first detection value and the second detection value.