JP2016056976A - Step-out detection system and step-out detection method for compressor in refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a step-out detection system for a compressor with components included generally in a refrigeration cycle of a heat pump system.SOLUTION: A refrigeration cycle comprises: a compressor 12, a condenser and an evaporator (an outdoor heat exchanger 14 and an indoor heat exchanger 32), a selector valve 13, an expansion valve 15, and a control part 40. Temperature detectors (temperature detectors 22, 23) are arranged between a discharge part of the compressor 12 and an intake of the condenser, and an outlet of the evaporator and a suction part of the compressor 12. The control part 40 determines a step-out state of the compressor 12 when the compressor 12 continues to operate for a predetermined time while a temperature difference in detected temperature between both the temperature detectors (temperature detectors 22, 23) is less than a predetermined value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a compressor step-out detection system and a step-out detection method in a refrigeration cycle.

  Heat pump refrigeration cycles are used in various devices such as air conditioners, refrigerators, water heaters, washing machines with drying functions, and vending machines. The refrigeration cycle includes a compressor that sends out high-temperature and high-pressure refrigerant, but depending on the conditions, the compressor may be stepped out. The compressor step-out must be detected and resolved promptly.

  Various measures for preventing step-out have been proposed for compressors used in heat pump refrigeration cycles. Examples thereof can be seen in Patent Documents 1 to 3.

  In Patent Document 1, in a motor drive control device that drives a motor having a large load torque fluctuation during one rotation of the rotor, such as a motor used in a one-piston rotary compressor, the torque control means determines the torque. When the torque command amount and the values detected by the pipe temperature detecting means and the outside air temperature detecting means are larger than the preset values, the target rotational speed is corrected by the target rotational speed correcting means to avoid the low speed region, An electric motor drive device that suppresses an increase in vibration and noise of an electric motor during an overload and prevents the electric motor from stepping out is described.

  In Patent Document 2, in a torque control device for an electric motor that drives an electric motor having a large variation in load torque during one rotation of the rotor, such as an electric motor used for a one-piston rotary compressor, it is determined by a torque control means. If the detected torque command amount and the value detected by the pipe temperature detecting means are larger than the preset value, the target rotational speed is corrected by the target rotational speed correcting means to avoid the low speed region and An electric motor drive device that suppresses an increase in vibration and noise and prevents the motor from stepping out is described.

  Patent Document 3 discloses a torque determined by a torque control unit in an electric motor driving apparatus that drives an electric motor having a large variation in load torque during one rotation of the rotor, such as an electric motor used in a one-piston rotary compressor. When the command amount and the value detected by the outside air temperature detecting means are larger than the preset value, the target rotational speed is corrected by the target rotational speed correcting means, thereby avoiding the low speed region and the vibration of the motor during overload. An electric motor drive device that suppresses an increase in noise and prevents the motor from stepping out is described.

JP2011-188628A JP 2011-120365 A JP 2010-239762 A

  Even if the step-out prevention technique described in Patent Documents 1 to 3 is implemented, step-out can not be completely prevented. In the unlikely event that a step-out occurs, it is also important to have a technology that detects it and links it to a step-out resolution measure.

  A conventional compressor out-of-step detection method is to monitor the current consumption of the compressor and to determine that the step-out occurs when the current value suddenly decreases. If it is determined that the step-out has occurred, the compressor has been restarted to eliminate the step-out.

  The above method has the following disadvantages. That is, in order to monitor the current consumption of the compressor, a current measuring means is necessary. By disposing current measuring means that are not originally related to temperature management, the cost is increased accordingly.

  The present invention has been made in view of the above points, and an object of the present invention is to configure a compressor step-out detection system with components that are generally included in a heat pump refrigeration cycle. It is another object of the present invention to provide a compressor step-out detection method performed by components generally included in a heat pump refrigeration cycle.

  In the compressor step-out detection system in the refrigeration cycle according to the present invention, the refrigeration cycle includes a compressor, a condenser, an evaporator, a switching valve, an expansion valve, and a control unit, and the discharge unit of the compressor And a temperature detector are arranged between the inlet of the condenser and between the outlet of the evaporator and the suction part of the compressor. The controller determines that the compressor is out of step when the operation of the compressor continues for a specified time in a state where the temperature difference between the detected temperatures of the two temperature detectors is less than a specified value. .

In the compressor step-out detection system in the refrigeration cycle having the above configuration, the control unit includes:
It is preferable to perform restart control of the compressor after determining that the compressor has stepped out.

  In the compressor step-out detection system in the refrigeration cycle having the above configuration, the control unit causes the compressor to step out even when the opening of the expansion valve changes more than a specified value and more than a specified speed. It is preferable to make a determination that it is present.

  In the compressor step-out detection method in the refrigeration cycle according to the present invention, the refrigeration cycle includes a compressor, a condenser, an evaporator, a switching valve, an expansion valve, and a control unit, and the discharge unit of the compressor Temperature detectors are arranged between the inlet of the condenser and the inlet of the condenser and between the outlet of the evaporator and the suction part of the compressor. The controller receives the temperature data output from the two temperature detectors, compares the temperature data from the two temperature detectors to calculate a temperature difference, and the temperature difference is less than a specified value. If the operation time of the compressor in that state is measured and the operation of the compressor in a state where the temperature difference is less than a specified value continues for a specified time, the compressor steps out. And sequentially performing a step of making a determination that the

  In the compressor step-out detection method in the refrigeration cycle having the above-described configuration, in addition to the step, the control unit monitors the opening of the expansion valve, and the opening is changed by a specified value or more and a specified speed or more. If so, it is preferable to perform a step of determining that the compressor is out of step.

  According to the present invention, a temperature detector generally provided in a heat pump refrigeration cycle is used, and the compressor step-out is determined by the temperature difference between the detected temperatures of the two temperature detectors. It is not necessary to add an additional component, and a step-out detection system and a step-out detection method can be provided at low cost.

It is a schematic block diagram of an air conditioner, and shows the state at the time of cooling operation. It is a schematic block diagram of an air conditioner, and shows the state during heating operation. It is a control block diagram of an air conditioner. It is a 1st flowchart explaining control of an air conditioner. It is a 2nd flowchart explaining control of an air conditioner. It is a 3rd flowchart explaining control of an air conditioner. It is a graph explaining the example of the compressor step-out determination at the time of air_conditionaing | cooling operation. It is a graph explaining the example of the compressor step-out determination at the time of heating operation, and shows an example when the outside air temperature is not so low. It is a graph explaining the example of the compressor step-out determination at the time of heating operation, Comprising: An example when external temperature is low is shown. It is a graph which shows the actual value of the compressor speed at the time of a step-out determination. It is a graph which shows the actual value of the expansion valve opening degree at the time of step-out determination. It is a graph which shows the 1st measured value of the temperature change of the temperature detector at the time of a step-out determination. It is a graph which shows the actual value of the target superheat degree at the time of a step-out determination, and actual superheat degree. It is a graph which shows the 2nd measured value of the temperature change of the temperature detector at the time of a step-out determination. It is a graph which shows the actual value of AC current at the time of a step-out determination. It is a graph which shows the 3rd measured value of the temperature change of the temperature detector at the time of a step-out determination.

<First Embodiment>
A compressor step-out detection system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4 and FIGS. 7 to 9. The compressor step-out detection system is realized in the air conditioner 1. The air conditioner 1 is a separate type air conditioner in which a heat pump refrigeration cycle is incorporated, and includes an outdoor unit 10 and an indoor unit 30.

  The outdoor unit 10 accommodates a compressor 12, a switching valve 13, an outdoor heat exchanger 14, an expansion valve 15, an outdoor fan 16, and the like in a housing 11 composed of sheet metal parts and synthetic resin parts. Yes. The switching valve 13 is a four-way valve. As the outdoor heat exchanger 14, a fin-and-tube heat exchanger or a parallel flow heat exchanger can be used. The outdoor heat exchanger 14 functions as a condenser during the cooling operation, and functions as an evaporator during the heating operation. As the expansion valve 15, a valve whose opening degree can be controlled is used. The outdoor fan 16 is a combination of a propeller fan and a motor.

  The outdoor unit 10 is connected to the indoor unit 30 through two refrigerant pipes 17 and 18. The refrigerant pipe 17 is mainly intended to flow a liquid refrigerant, and a pipe that is thinner than the refrigerant pipe 18 is used. Therefore, the refrigerant pipe 17 may be referred to as “liquid pipe”, “narrow pipe”, or the like. The refrigerant pipe 18 is mainly intended to flow a gaseous refrigerant, and a thicker pipe is used as compared with the refrigerant pipe 17. Therefore, the refrigerant pipe 18 may be referred to as “gas pipe”, “thick pipe”, or the like. For example, HFC R410A or R32 is used as the refrigerant.

  In the refrigerant pipe inside the outdoor unit 10, a two-way valve 19 is provided in the refrigerant pipe connected to the refrigerant pipe 17, and a three-way valve 20 is provided in the refrigerant pipe connected to the refrigerant pipe 18. The two-way valve 19 and the three-way valve 20 are closed when the refrigerant pipes 17 and 18 are removed from the outdoor unit 10 to prevent the refrigerant from leaking from the outdoor unit 10 to the outside. When it is necessary to release the refrigerant from the outdoor unit 10 or from the entire refrigeration cycle including the indoor unit 30, the refrigerant is discharged through the three-way valve 20.

  The indoor unit 30 houses an indoor heat exchanger 32, an indoor fan 33, and the like in a housing 31 formed of synthetic resin parts. The indoor heat exchanger 32 is a combination of three indoor heat exchangers 32 </ b> A, 32 </ b> B, and 32 </ b> C like a roof that covers the indoor fan 33. As the indoor heat exchangers 32A, 32B, and 32C, fin-and-tube heat exchangers and parallel flow heat exchangers can be used. The indoor heat exchanger 32 functions as an evaporator during the cooling operation and functions as a condenser during the heating operation. The indoor fan 33 is a combination of a motor and a cross flow fan.

  In order to control the operation of the air conditioner 1, it is indispensable to know the temperature of each place. For this purpose, temperature detectors are arranged in the outdoor unit 10 and the indoor unit 30. In the outdoor unit 10, a temperature detector 21 is disposed in the outdoor heat exchanger 14, a temperature detector 22 is disposed in a discharge pipe 12 a serving as a discharge unit of the compressor 12, and a suction pipe serving as a suction unit of the compressor 12. A temperature detector 23 is arranged at 12 b, a temperature detector 24 is arranged in the refrigerant pipe between the expansion valve 15 and the two-way valve 19, and a temperature detector 25 for measuring the outside air temperature at a predetermined location inside the housing 11. Is placed. In the indoor unit 30, the temperature detector 34 is arrange | positioned at the indoor heat exchanger 32, and the temperature detector 35 is arrange | positioned at the blower outlet. Each of the temperature detectors 21, 22, 23, 24, 25, 34, and 35 is formed of a thermistor.

  The control unit 40 shown in FIG. 3 controls the overall control of the air conditioner 1. The control unit 40 performs control so that the room temperature reaches a target value set by the user.

  The control unit 40 issues operation commands to the compressor 12, the switching valve 13, the expansion valve 15, the outdoor fan 16, and the indoor fan 33. The control unit 40 receives output signals of the detected temperatures from the temperature detectors 21 to 25 and the temperature detector 34. The control unit 40 issues operation commands to the compressor 12, the outdoor fan 16, and the indoor fan 33 while referring to output signals from the temperature detectors 21 to 25 and the temperature detectors 34 and 35, and the switching valve 13 and the expansion valve 13 are expanded. A command for switching the state is issued to the valve 15.

  FIG. 1 shows a state in which the air conditioner 1 is performing a cooling operation or a defrosting operation. At this time, the compressor 12 circulates the refrigerant in a cooling mode, that is, a circulation mode in which the refrigerant discharged from the compressor 12 first enters the outdoor heat exchanger 14.

  The high-temperature and high-pressure refrigerant discharged from the compressor 12 enters the outdoor heat exchanger 14 where heat exchange with outdoor air is performed. The refrigerant dissipates heat to the outdoor air and condenses. The refrigerant which is condensed to become liquid enters the expansion valve 15 from the outdoor heat exchanger 14 and is decompressed there. The decompressed refrigerant is sent to the indoor heat exchanger 32, expands to a low temperature and low pressure, and lowers the surface temperature of the indoor heat exchanger 32. The indoor heat exchanger 32 whose surface temperature has fallen absorbs heat from the indoor air, thereby cooling the room. After the heat absorption, the low-temperature gaseous refrigerant returns to the compressor 12. The air flow generated by the outdoor fan 16 promotes heat dissipation from the outdoor heat exchanger 14, and the air flow generated by the indoor fan 33 promotes heat absorption of the indoor heat exchanger 32.

  FIG. 2 shows a state where the air conditioner 1 is performing a heating operation. At this time, the switching valve 13 is switched to reverse the refrigerant flow during the cooling operation. The compressor 12 circulates the refrigerant in a circulation mode during heating, that is, in a circulation mode in which the refrigerant discharged from the compressor 12 first enters the indoor heat exchanger 32.

  The high-temperature and high-pressure refrigerant discharged from the compressor 12 enters the indoor heat exchanger 32 where heat exchange with room air is performed. The refrigerant dissipates heat to the room air, and the room air is warmed. The refrigerant that has dissipated heat and is condensed to become liquid enters the expansion valve 15 from the indoor heat exchanger 32 and is decompressed there. The decompressed refrigerant is sent to the outdoor heat exchanger 14 and expands to a low temperature and low pressure, thereby lowering the surface temperature of the outdoor heat exchanger 14. The outdoor heat exchanger 14 whose surface temperature has dropped absorbs heat from the outdoor air. After the heat absorption, the low-temperature gaseous refrigerant returns to the compressor 12. The air flow generated by the indoor fan 33 promotes heat dissipation from the indoor heat exchanger 32, and the air flow generated by the outdoor fan 16 promotes heat absorption by the outdoor heat exchanger 14.

  In the compressor step-out detection system according to the present invention, the detected temperatures output from the two temperature detectors are used to detect the step-out of the compressor 12. The first temperature detector is a temperature detector arranged between the discharge part of the compressor 12 and the inlet of the condenser. In the first embodiment, this corresponds to the temperature detector 22 arranged in the discharge pipe 12a. The second temperature sensor is a temperature sensor arranged between the outlet of the evaporator and the suction part of the compressor 12. In the first embodiment, this corresponds to the temperature detector 23 arranged in the suction pipe 12b.

  The temperature detector used to detect the step-out of the compressor 12 is not limited to the temperature detector 22 and the temperature detector 23. At the time of the cooling operation, the temperature detector 22 can be used as long as the temperature detector is disposed in a section having both ends of the discharge pipe 12a and the inlet of the outdoor heat exchanger 14. Further, as long as the temperature detector is disposed in a section having both the outlet of the indoor heat exchanger 32 and the suction pipe 12b as both ends, it can be replaced with the temperature detector 23. At the time of heating operation, as long as the temperature detector is disposed in a section having both ends of the discharge pipe 12a and the inlet of the indoor heat exchanger 32, the temperature detector 22 can be used instead. Further, as long as the temperature detector is disposed in a section having both the outlet of the outdoor heat exchanger 14 and the suction pipe 12b as both ends, it can be replaced with the temperature detector 23. Here, the description proceeds based on a configuration in which the detected temperatures output from the temperature detectors 22 and 23 are used for step-out detection of the compressor 12.

  The control of the compressor step-out detection system according to the first embodiment of the present invention is performed as shown in the flowchart of FIG.

  The step-out detection of the compressor 12 starts its function when the operation of the compressor 12 is stabilized.

  In step # 101, the control unit 40 receives the detected temperatures output from the temperature detectors 22 and 23.

  In subsequent step # 102, the control unit 40 checks whether or not the detected temperature input from the temperature detectors 22 and 23 is lower than a specified value. If so, the process proceeds to step # 103.

  In step # 103, the control unit 40 compares the detected temperatures input from the temperature detectors 22 and 23 and calculates a temperature difference. If the compressor 12 is operating normally without causing step-out, the temperature between the discharge part of the compressor 12 and the inlet of the condenser, and the temperature between the outlet of the evaporator and the suction part of the compressor 12 There is a reasonable temperature difference between

  In subsequent step # 104, the control unit 40 checks whether or not the temperature difference calculated in step # 103 is less than a specified value. If the temperature difference does not reach the specified value, there is a suspicion of step-out, and the process proceeds to step # 105. If the temperature difference satisfies the specified value, there is no fear of step-out, and the process returns to step # 101.

  In step # 105, the control unit measures how long the operation of the compressor 12 continues in a situation where the temperature difference between the detected temperatures of the temperature detectors 22 and 23 is less than a specified value.

  In subsequent step # 106, the control unit 40 checks whether or not the operation continuation time of the compressor 12 measured in step # 105 has reached a specified time (for example, 10 seconds). When the operation continuation time reaches the specified time, the control unit 40 determines that the compressor 12 has stepped out. When the result that the operation continuation time of the compressor 12 does not reach the specified time is reached, the control unit 40 determines that there has been some problem in the processing so far, and performs step-out detection again from step # 101.

  After determining that the compressor 12 has stepped out, the control unit 40 performs restart control of the compressor 12 to eliminate stepping out.

  Examples of step-out determination are shown in the graphs of FIGS. In each graph, the horizontal axis is the cooling / heating capacity (unit: kW), and the vertical axis is the temperature between the discharge part of the compressor and the inlet of the condenser, and between the outlet of the evaporator and the suction part of the compressor. Temperature difference (unit: ° C.). The graph of FIG. 7 is an example of cooling operation at an outside air temperature of 35 ° C., the graph of FIG. 8 is an example of heating operation at an outside air temperature of 7 ° C., and FIG. 9 is an example of heating operation at an outside air temperature of 2 ° C. If the temperature difference remains in the area below the broken line drawn below the actual plot value (the lower broken line in the two broken lines in the figure), the compressor is out of step. Is made.

Second Embodiment
In the compressor step-out detection system according to the second embodiment of the present invention, control is performed according to the flowchart of FIG.

  The step-out detection of the compressor 12 starts its function when the operation of the compressor 12 is stabilized.

  In Step # 201, the control unit 40 receives the detected temperatures output from the temperature detectors 22 and 23.

  In subsequent step # 202, the control unit 40 checks whether or not the detected temperature input from the temperature detectors 22 and 23 is below a specified value. If not, the process proceeds to step # 203.

  The controller 40 constantly monitors the opening degree of the expansion valve 15. In both the outdoor heat exchanger 14 and the indoor heat exchanger 32, a refrigerant flow rate equal to or higher than a specified value is required in order to bring predetermined overheating to the overheating region. When the refrigerant flow rate decreases due to the step-out, the decrease in the refrigerant flow rate is compensated by increasing the opening of the expansion valve 15. In such a case, the opening degree of the expansion valve 15 changes greatly and rapidly. Therefore, the step-out of the compressor 12 can also be detected by monitoring the opening degree of the expansion valve 15.

  Specifically, monitoring the opening degree of the expansion valve 15 means monitoring the operation of the stepping motor for opening and closing the expansion valve 15. In step # 203, the control unit 40 checks whether or not the opening degree of the expansion valve 15 has changed more than a specified value and more than a specified speed. When a large movement of the stepping motor of the expansion valve 15 occurs, for example, 30 steps in a total number of steps of 500 within a specified short time, a change of “more than a specified value and more than a specified speed” has occurred. The control unit 40 determines. At this time, the determination “step out according to the determination criterion of the opening degree of the expansion valve” is made, and the process proceeds to step # 204.

  In step # 204, the control unit 40 compares the detected temperatures input from the temperature detectors 22 and 23 and calculates a temperature difference. If the compressor 12 is operating normally without causing step-out, the temperature between the discharge part of the compressor 12 and the inlet of the condenser, and the temperature between the outlet of the evaporator and the suction part of the compressor 12 There is an appropriate temperature difference between and, but this is not the case if there is a step-out.

  In subsequent step # 205, the control unit 40 checks whether or not the temperature difference calculated in step # 204 is less than a specified value. If the temperature difference does not reach the specified value, it means that there is a suspicion of step-out even in light of this criterion, and the process proceeds to step # 206. If the temperature difference satisfies the specified value, it means “step out according to the criterion of expansion valve opening”, but the “step out” determination cannot be confirmed yet. Returning to 201, the step-out detection is performed again.

  In step # 206, the control unit measures how long the operation of the compressor 12 continues in a situation where the temperature difference between the temperatures detected by the temperature detectors 22 and 23 is less than a specified value.

  In subsequent step # 207, the control unit 40 checks whether or not the operation continuation time of the compressor 12 measured in step # 206 has reached a specified time (for example, 10 seconds). When the operation continuation time reaches the specified time, the control unit 40 determines that the compressor 12 is out of step. When the result that the operation continuation time of the compressor 12 does not reach the specified time is reached, the control unit 40 determines that there has been some problem in the processing so far, and repeats step-out detection from step # 201.

  After determining that the compressor 12 has stepped out, the control unit 40 performs restart control of the compressor 12 to eliminate stepping out.

  In the flowchart of FIG. 5, after determining “step out” with the change in the opening of the expansion valve 15, the step out determination is performed again with the temperature difference between the detected temperatures input from the temperature detectors 22 and 23, and the step out determination is performed. However, the step-out determination may be determined when it is determined as “step out” from the change in the opening degree of the expansion valve 15.

<Third Embodiment>
In the compressor step-out detection system according to the third embodiment of the present invention, the temperature between the discharge portion of the compressor and the inlet of the condenser in the step-out determination, and between the outlet of the evaporator and the suction portion of the compressor. As a determination material for determining the temperature difference between the two, a means different from the expansion valve opening degree of the second embodiment is proposed. That is, the change in the blow-out temperature of the indoor unit is monitored, and the step-out determination is performed in consideration of the temperature change amount. In the third embodiment, the control is performed according to the flowchart of FIG.

  The step-out detection of the compressor 12 starts its function when the operation of the compressor 12 is stabilized.

  In step # 301, the control unit 40 receives the detected temperatures output from the temperature detectors 22 and 23.

  In subsequent step # 302, the control unit 40 checks whether or not the detected temperature input from the temperature detectors 22 and 23 is lower than a specified value. If not, the process proceeds to step # 303.

  The control unit 40 constantly monitors the temperature of air blown from the indoor unit 30. In both the outdoor heat exchanger 14 and the indoor heat exchanger 32, a refrigerant flow rate equal to or higher than a specified value is required in order to bring predetermined overheating to the overheating region. When the refrigerant flow rate is reduced due to the step-out, the blowout temperature of the indoor unit 30 changes greatly. Therefore, the step-out of the compressor 12 can be detected also by monitoring the blow-out temperature of the indoor unit 30.

  Monitoring the blowout temperature of the indoor unit 30 specifically means monitoring the temperature detected by the temperature detector 35 disposed at the blowout port of the indoor unit 30. In step # 303, the control unit 40 checks whether or not the blowout temperature of the indoor unit 30 has changed by more than a specified value. For example, when a normal operation is performed at a cooling operation set temperature of 18 ° C., and a change in the blowing temperature in a range of 18 ° C. to ± 1 to 3 ° C. occurs within a specified short time, a change of “above a specified value” occurs. The controller 40 determines that it has occurred. At this time, the determination “step out according to the determination criterion of indoor unit outlet temperature” is made, and the process proceeds to step # 304.

  In step # 304, the control unit 40 compares the detected temperatures input from the temperature detectors 22 and 23 and calculates a temperature difference. If the compressor 12 is operating normally without causing step-out, the temperature between the discharge part of the compressor 12 and the inlet of the condenser, and the temperature between the outlet of the evaporator and the suction part of the compressor 12 There is an appropriate temperature difference between and, but this is not the case if there is a step-out.

  In subsequent step # 305, the control unit 40 checks whether or not the temperature difference calculated in step # 304 is less than a specified value. If the temperature difference does not satisfy the specified value, it means that there is a suspicion of step-out even in light of this criterion, and the process proceeds to step # 306. If the temperature difference satisfies the specified value, it means “step out according to the criterion of expansion valve opening”, but the “step out” determination cannot be confirmed yet. Returning to 301, step-out detection is performed again.

  In step # 306, the control unit measures how long the operation of the compressor 12 continues in a situation where the temperature difference between the temperatures detected by the temperature detectors 22 and 23 is less than a specified value.

  In subsequent step # 307, the control unit 40 checks whether or not the operation continuation time of the compressor 12 measured in step # 206 has reached a specified time (for example, 10 seconds). When the operation continuation time reaches the specified time, the control unit 40 determines that the compressor 12 is out of step. When the result that the operation continuation time of the compressor 12 does not reach the specified time is reached, the control unit 40 determines that there has been some problem in the processing so far, and repeats step-out detection from step # 301.

  After determining that the compressor 12 has stepped out, the control unit 40 performs restart control of the compressor 12 to eliminate stepping out.

  The graphs of FIGS. 10 to 16 show examples of actually measured values of each parameter at the time of step-out determination. The horizontal axis of each graph is time, but the vertical axis is different for each graph. That is, the vertical axis of the graph of FIG. 10 is the rotation speed of the compressor and is expressed in rpm. The vertical axis of the graph of FIG. 11 represents the opening degree of the expansion valve, and is represented by the step number stp of the stepping motor. The vertical axis of the graph in FIG. 12 is the temperature detected by the outdoor heat exchanger and the temperature detector disposed in the indoor heat exchanger, and is expressed in ° C. The vertical axis of the graph in FIG. 13 represents the target superheat degree and the actually measured superheat degree, and is expressed in deg. The vertical axis of the graph of FIG. 14 is the temperature detected by the temperature detectors arranged at the discharge part and the suction part of the compressor and the temperature detector arranged for measuring the outside air temperature, and is expressed in ° C. . The vertical axis of the graph of FIG. 15 is the AC current flowing through the motor of the compressor, and is represented by A. The vertical axis of the graph of FIG. 16 is the temperature detected by the temperature detectors arranged at the discharge part and the suction part of the compressor and the temperature detector arranged for measuring the outside air temperature, and is expressed in ° C. . FIG. 15 shows that the actual value of the temperature difference is about 92 ° C. while the specified value of the temperature difference between the discharge portion and the suction portion of the compressor is 70 ° C. under the condition of the outside air temperature of 2 ° C. This is an example.

  In each of the graphs from FIG. 10 to FIG. 16, the numerical value fluctuates with respect to the vertical axis in the time zone from 16:40:00 to 16:45:00. That is, the compressor stepped out here.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention is widely applicable to a heat pump type refrigeration cycle.

DESCRIPTION OF SYMBOLS 1 Air conditioner 10 Outdoor unit 11 Case 12 Compressor 13 Switching valve 14 Outdoor heat exchanger 15 Expansion valve 16 Outdoor fan 21, 22, 23, 24, 25 Temperature detector 30 Indoor unit 31 Case 32, 32A, 32B , 32C Indoor heat exchanger 33 Indoor fan 34, 35 Temperature detector

Claims (5)

In a refrigeration cycle including a compressor, a condenser, an evaporator, a switching valve, an expansion valve, and a control unit,
Temperature detectors are arranged between the discharge part of the compressor and the inlet of the condenser and between the outlet of the evaporator and the suction part of the compressor, respectively.
The controller determines that the compressor is out of step when the operation of the compressor continues for a specified time in a state where the temperature difference between the detected temperatures of the two temperature detectors is less than a specified value. A step-out detection system for a compressor in a refrigeration cycle.   The step-out of the compressor in the refrigeration cycle according to claim 1, wherein the control unit performs restart control of the compressor after determining that the compressor is out of step. Detection system.   2. The control unit according to claim 1, wherein the control unit determines that the compressor is out of step even when the opening degree of the expansion valve changes more than a specified value and more than a specified speed. 3. A step-out detection system for a compressor in the refrigeration cycle according to 2. A compressor, a condenser, an evaporator, a switching valve, an expansion valve, and a control unit, and are arranged between the discharge unit of the compressor and the inlet of the condenser and between the outlet of the evaporator and the compressor. In the refrigeration cycle in which the temperature detectors are arranged between the suction parts,
The control unit is
Receiving temperature data output by both the temperature detectors;
Comparing temperature data from both temperature detectors to calculate a temperature difference;
If the temperature difference is less than a specified value, measuring the operating time of the compressor in that state;
A step of determining that the compressor is out of step when the operation of the compressor in a state where the temperature difference is less than a specified value continues for a specified time;
The step-out detection method of the compressor in the refrigerating cycle characterized by performing sequentially. The method for detecting a step-out of a compressor in a refrigeration cycle according to claim 4, wherein the control unit performs the following step in addition to the step:
Monitoring the opening of the expansion valve, and determining that the compressor has stepped out when the opening changes more than a specified value and more than a specified speed.

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