JP6318021B2 - Heat pump chiller - Google Patents

Description

  The present invention relates to a heat pump chiller that cools a liquid to be cooled by heat exchange with a refrigerant circulating in a refrigeration cycle.

  As a conventional heat pump chiller, Patent Document 1 discloses a configuration shown in FIG. 9 in order to prevent freezing of a chiller using a refrigerator. The chiller of Patent Document 1 executes a refrigeration cycle with a compressor 501, a condenser 502, an expansion valve 503, and an evaporator 504, and cools a liquid to be cooled by heat exchange with a refrigerant circulating in the cycle. .

  In the chiller of Patent Document 1, a liquid electromagnetic valve 505 is provided on the primary side of the expansion valve 503, and the temperature on the primary side of the liquid electromagnetic valve 505 is monitored by the first temperature sensor 506 at the time of activation. When the temperature detected by the first temperature sensor 506 is equal to or lower than the first set value, the bypass valve 507 is opened while the liquid electromagnetic valve 505 is closed, and the refrigerant discharged from the compressor 501 is supplied to the second expansion valve 503. Bypass to the next side. By bypassing the refrigerant in this way, the refrigerant does not circulate in the refrigeration cycle, and freezing of the circulating water (cooled liquid) from the cold water tank 510 in the evaporator (heat exchanger) 504 can be prevented.

Japanese Patent No. 5098472

  However, in the configuration of Patent Document 1, the temperature on the primary side of the liquid electromagnetic valve 505 increases when reaching a steady operation, and thus it is difficult to divert the above technique to prevent freezing during operation.

  An object of this invention is to provide the heat pump type chiller which can aim at the freezing prevention of a to-be-cooled liquid including the driving | operation from start.

  In order to achieve the above object, a heat pump chiller according to the present invention includes a compressor that sucks and discharges refrigerant, a refrigerant-air heat exchanger, an expansion valve, and a refrigerant-circulating liquid heat that exchanges heat between the circulating liquid and the refrigerant. A heat pump chiller provided with an exchanger and provided with a circulation pump in the flow path of the circulating fluid, wherein temperature sensors are respectively provided at the circulating fluid inlet, the circulating fluid outlet, and the surface of the refrigerant-circulating fluid heat exchanger. And a pressure sensor is provided in the refrigerant suction path of the compressor, and one of a temperature detected by the three temperature sensors or a refrigerant evaporation temperature converted from the pressure detected by the pressure sensor is equal to or lower than a predetermined temperature. When this is detected, the compressor is stopped and the circulating pump is operated.

  According to the above configuration, by monitoring the temperature corresponding to the temperature of the circulating fluid, it is possible to prevent the circulating fluid from freezing over the entire operation period of the chiller.

  In the heat pump chiller, a plurality of controllers may receive the detection signals from the three temperature sensors and the pressure sensor in a distributed manner.

  According to said structure, the risk reduction with respect to controller abnormality can be aimed at by distributing the receiving controller of a sensor signal.

  In the heat pump chiller, the first controller receives signals from the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the pressure sensor at the refrigerant suction path of the compressor, and the refrigerant- The second controller receives signals from the circulating fluid outlet of the circulating fluid heat exchanger and the surface temperature sensor, and the first controller has a function of detecting an abnormality in the received signal itself. At start-up, the circulating pump is operated before the compressor is driven, and after the operation of the circulating pump and before the compressor is started, detection by the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger The absolute value of the temperature difference between the temperature and the temperature detected by the temperature sensor at the circulating fluid outlet is greater than or equal to the first predetermined value, or When it is detected that the absolute value of the temperature difference from the temperature detected by the temperature sensor is greater than or equal to a second predetermined value greater than the first predetermined value, the driving of the compressor is stopped. it can.

  According to said structure, the presence or absence of abnormality of a temperature sensor can be confirmed before a compressor is driven, and the reliability of freezing prevention detection improves.

  In the heat pump chiller, the first controller receives signals from the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the pressure sensor at the refrigerant suction path of the compressor, and the refrigerant- A connection relay that receives signals from the circulating fluid outlet of the circulating fluid heat exchanger and the surface temperature sensor, and is opened and closed by the first controller, and is connected between the circulating pump and the power source. A first connection relay provided and a connection relay opened and closed by the second controller, wherein a second connection relay provided between the circulation pump and a power source can be provided in parallel.

  According to the above configuration, since power can be supplied to the circulation pump from any controller of the first controller and the second controller, the operational safety of the circulation pump against controller abnormality is improved.

  The heat pump chiller according to the present invention is provided with a temperature sensor at each of a circulating fluid inlet, a circulating fluid outlet, and a surface of a refrigerant-circulating fluid heat exchanger, and a pressure sensor at a refrigerant suction path of the compressor. When it is detected that one of the temperature detected by two temperature sensors or the refrigerant evaporation temperature converted from the pressure detected by the pressure sensor is equal to or lower than a predetermined temperature, the compressor is stopped and the circulation Operate the pump.

  As a result, the temperature corresponding to the temperature of the circulating fluid is monitored, and the anti-freezing control of the circulating fluid is performed based on these temperatures, thereby preventing the circulating fluid from being frozen over the entire operation period of the chiller. Play.

It is a block diagram which shows schematic structure of the heat pump type chiller which concerns on this Embodiment. It is a block diagram which shows the control system which performs the freeze prevention control of the circulating fluid in the heat pump chiller which concerns on this Embodiment. FIG. 3 is a diagram for explaining anti-freezing control at normal time in the control system shown in FIG. 2. FIG. 3 is a diagram illustrating freeze prevention control when the main CPU is abnormal in the control system shown in FIG. 2. FIG. 3 is a diagram for explaining anti-freezing control when a sensor input to the main CPU is abnormal in the control system shown in FIG. 2. FIG. 3 is a diagram illustrating a control operation of anti-freezing control when a sub CPU is abnormal in the control system shown in FIG. 2. FIG. 3 is a diagram for explaining anti-freezing control when a sensor input to the sub CPU is abnormal in the control system shown in FIG. 2. It is a flowchart which shows sensor abnormality detection operation | movement in the heat pump chiller which concerns on this Embodiment. It is a block diagram which shows schematic structure of the conventional heat pump type chiller.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a heat pump chiller (hereinafter simply referred to as a chiller) 100 according to the present embodiment. The chiller 100 generally includes a refrigerant circuit 110 that circulates a refrigerant and a circulating fluid circuit 200 that circulates a circulating fluid. The control device 140 controls the operation of the entire chiller 100.

  The refrigerant circuit 110 includes the compressor 10, the refrigerant-air heat exchanger 20, the expansion valve 40, and the refrigerant-circulating liquid heat exchanger 50. The chiller 100 performs the refrigeration cycle by circulating the refrigerant in the order of the compressor 10, the refrigerant-air heat exchanger 20, the expansion valve 40, and the refrigerant-circulated liquid heat exchanger 50. The chiller 100 cools the circulating fluid by heat exchange (heat exchange between the circulating fluid and the refrigerant) in the refrigerant-circulating fluid heat exchanger 50 (cooling operation).

  In the refrigerant circuit 110, the compressor 10 compresses and discharges the sucked refrigerant. The refrigerant-air heat exchanger 20 exchanges heat between the refrigerant and air (specifically, outside air). The expansion valve 40 expands the refrigerant compressed by the compressor 10. The refrigerant-circulating liquid heat exchanger 50 exchanges heat between the circulating liquid and the refrigerant. The compressor 10 may be a unit in which a plurality of compressors are connected in parallel. Similarly, the refrigerant-air heat exchanger 20 is a unit in which a plurality of refrigerant-air heat exchangers are connected in parallel. There may be.

  The expansion valve 40 can adjust the opening degree by an instruction signal from the control device 140. Thereby, the expansion valve 40 can adjust the circulation amount of the refrigerant in the refrigerant circuit 110. Specifically, the expansion valve 40 is formed by connecting a plurality of expansion valves that can be closed in parallel. By doing so, the expansion valve 40 can adjust the circulation amount of the refrigerant in the refrigerant circuit 110 by combining the expansion valves to be opened.

  In the chiller 100 shown in FIG. 1, the refrigerant-air heat exchanger fan 30 is provided to efficiently perform heat exchange in the refrigerant-air heat exchanger 20. The engine 60 is provided as a drive source that drives the compressor 10. However, in the present invention, the drive source for driving the compressor 10 is not limited to the engine, and another drive source (for example, a motor) may be used.

  The chiller 100 according to the present embodiment is configured to perform a heating operation in addition to the cooling operation. For this reason, the chiller 100 includes a four-way valve 111 and a bridge circuit 112 on the refrigerant discharge side of the compressor 10.

  The four-way valve 111 switches the refrigerant flow direction between the cooling operation and the heating operation according to an instruction signal from the control device 140. That is, during the cooling operation, the inflow port (lower side in FIG. 1) and one connection port (left side in FIG. 1) are connected, and the other connection port (right side in FIG. 1) and the outflow port ( 1 (upper line in FIG. 1). Further, during the heating operation, the inlet (lower side in FIG. 1) and the other connection port (right side in FIG. 1) are connected, and one connection port (left side in FIG. 1) and the outlet ( 1 (upper line in FIG. 1).

  The bridge circuit 112 automatically switches the flow direction of the refrigerant between the cooling operation and the heating operation. The bridge circuit 112 includes four check valves (a first check valve 112a, a second check valve 112b, a third check valve 112c, and a fourth check valve 112d). The first check valve 112a and the second check valve 112b are connected in series so that the refrigerant flows in the same direction, and constitute a first check valve train. The third check valve 112c and the fourth check valve 112d are connected in series so that the refrigerant flows in the same direction, and constitute a second check valve train. The first check valve row and the second check valve row are connected in parallel so that the refrigerant flows in the same direction.

  In the bridge circuit 112, a connection point between the first check valve 112a and the second check valve 112b is a first intermediate connection point P1, and the connection between the first check valve 112a and the third check valve 112c. The connection point between the third check valve 112c and the fourth check valve 112d is the second intermediate connection point P3, and the second check valve 112b and the fourth check point 112b. A connection point with the check valve 112d is an inflow connection point P4.

  During the cooling operation of the chiller 100, the refrigerant flow path includes the compressor 10, the four-way valve 111, the refrigerant-air heat exchanger 20, the bridge circuit 112 (P1 to P2), the expansion valve 40, and the bridge circuit 112 (P4 to P3). The refrigerant-circulating fluid heat exchanger 50, the four-way valve 111, and the compressor 10 become the refrigeration cycle. Further, during the heating operation of the chiller 100, the refrigerant flow path includes the compressor 10, the four-way valve 111, the refrigerant-circulating fluid heat exchanger 50, the bridge circuit 112 (P3 to P2), the expansion valve 40, and the bridge circuit 112 (P4). To P1), the refrigerant-air heat exchanger 20, the four-way valve 111, and the compressor 10 are performed, and the heating cycle is executed.

  In the present embodiment, chiller 100 further includes an oil separator 81, an accumulator 82, and a receiver 83. The oil separator 81 separates the lubricating oil of the compressor 10 contained in the refrigerant, and returns the separated lubricating oil to the compressor 10. The accumulator 82 separates the refrigerant liquid that has not completely evaporated in the refrigerant-circulated liquid heat exchanger 50 acting as an evaporator or the refrigerant-air heat exchanger 20 acting as an evaporator. The receiver 83 temporarily stores the high-pressure liquid refrigerant from the bridge circuit 112.

  The chiller 100 according to the present embodiment includes a four-way valve 111 and a bridge circuit 112 so that the cooling operation and the heating operation can be switched. The present invention is characterized by the operation during the cooling operation. It is what has. For this reason, this invention is applicable also to the chiller which can implement only a cooling operation.

  Next, the circulating fluid circuit 200 will be described. The circulating fluid flowing through the circulating fluid circuit 200 becomes a liquid to be cooled that is cooled by heat exchange in the refrigerant-circulating fluid heat exchanger 50 during the cooling operation. Further, during the heating operation, the liquid to be heated is heated by heat exchange in the refrigerant-circulating liquid heat exchanger 50. The circulating fluid is used, for example, as cold water or hot water used in a building air conditioning system. For example, water is used as the circulating fluid, but the present invention is not limited to this, and a solution in which an antifreeze or the like is mixed in water may be used.

  The circulating fluid circuit 200 includes an inflow pipe 211, an outflow pipe 212, and a circulation pump 300. The circulating fluid is introduced into the refrigerant-circulating fluid heat exchanger 50 via the inflow pipe 211, and the temperature is adjusted in the refrigerant-circulating fluid heat exchanger 50. The circulating fluid whose temperature has been adjusted is discharged from the chiller 100 through the outflow pipe 212. The circulating fluid circuit 200 included in the chiller 100 basically forms only a part of a closed circuit through which the circulating fluid flows. That is, when the chiller 100 according to the present embodiment is used for an air conditioning system in a building, the circulating fluid circuit on the air conditioning system side and the circulating fluid circuit 200 on the chiller 100 side are connected to form a closed circuit. Circulating fluid flows in the circuit. The circulation pump 300 is a pump for circulating the circulating fluid in the closed circuit. In the configuration shown in FIG. 1, the circulation pump 300 is provided in the outflow pipe 212, but may be provided in the inflow pipe 211.

  The chiller 100 according to the present embodiment includes an inflowing circulating fluid temperature sensor TWR, an outflowing circulating fluid temperature sensor TWL, a heat exchanger surface temperature sensor TWS, and a pressure sensor PL in order to prevent the circulating fluid from freezing during the cooling operation. I have.

  The inflowing circulating liquid temperature sensor TWR is provided in the inflow pipe 211 and detects the temperature of the circulating liquid (specifically, the circulating liquid in the inflow pipe 211) flowing into the refrigerant-circulating liquid heat exchanger 50. The outflow circulating fluid temperature sensor TWL is provided in the outflow pipe 212 and detects the temperature of the circulating liquid flowing out from the refrigerant-circulating liquid heat exchanger 50 (specifically, the circulating liquid in the outflow pipe 212). The heat exchanger surface temperature sensor TWS is provided on the surface of the refrigerant-circulating liquid heat exchanger 50 and detects the surface temperature. The pressure sensor PL is provided in the refrigerant suction path of the compressor 10 and detects the pressure of the refrigerant flowing out from the refrigerant-circulated liquid heat exchanger 50. Note that the refrigerant evaporating temperature of the refrigerant flowing out of the refrigerant-circulating fluid heat exchanger 50 is obtained from the pressure detected by the pressure sensor PL.

  The control device 140 performs the following control based on detection signals from various sensors in order to prevent the circulating fluid from freezing during the cooling operation. Specifically, the temperature detected by any of the inflowing circulating fluid temperature sensor TWR, the outflowing circulating fluid temperature sensor TWL, and the heat exchanger surface temperature sensor TWS, or the refrigerant evaporation temperature converted from the detected pressure of the pressure sensor PL is predetermined. When it is detected that the temperature is lower than (eg, 2 ° C.), the compressor 10 is stopped and the circulation pump 300 is operated.

  That is, when it is detected that any one of the four temperatures is equal to or lower than a predetermined temperature (for example, 2 ° C.), it is determined that the circulating fluid may be frozen if the cooling operation is continued as it is. Control for preventing this is executed. Specifically, the refrigeration cycle of the refrigerant circuit 110 is stopped by stopping the compressor 10, and the circulating pump 300 is operated to make it difficult to freeze the circulating fluid in the circulating fluid circuit 200. Note that the above operation is continued until all of the four temperatures are equal to or higher than a predetermined temperature. As described above, in the chiller 100 according to the present embodiment, freezing can be prevented over the entire operation period of the chiller by constantly monitoring the temperature corresponding to the temperature of the circulating fluid.

  In the chiller 100 according to the present embodiment, the control device 140 is preferably formed by a plurality of controllers, and the detection signals of the three temperature sensors and the pressure sensors are distributed and received by the plurality of controllers. In this way, by distributing the sensor signal reception controllers, it is possible to reduce the risk of controller abnormality. A configuration for distributing the reception controllers will be described in detail below.

  As shown in FIG. 2, the control device 140 includes a main board 141 and a sub board 142. A main CPU (first controller) 143 is mounted on the main board 141, and a sub CPU ( A second controller 144 is mounted. The main CPU 143 and the sub CPU 144 are connected via a communication line 145 so that they can communicate with each other.

  In the example of FIG. 2, the detection signal of the outflow circulating fluid temperature sensor TWL and the detection signal of the pressure sensor PL are input to the main CPU 143, and the detection signal of the inflowing circulating fluid temperature sensor TWR and the heat exchanger surface temperature sensor TWS are input to the sub CPU 144. It is assumed that the detection signal is input.

  Further, the main CPU 143 can supply power to the motor 301 by controlling the connection relay RY1 (first connection relay) in the power board 146. The sub CPU 144 can control the connection relay RY2 (second connection relay) and the connection relay RY (MC) (second connection relay) to supply power to the motor 301. The motor 301 is a motor for driving the circulation pump 300, and the circulation pump 300 operates by supplying power to the motor 301. That is, a first connection relay (connection relay RY1) opened and closed by the main CPU 143 and a second connection relay (connection relay RY2 and connection relay RY (MC)) opened and closed by the sub CPU 144 are provided in parallel. The motor 301 can be supplied with power to the circulation pump from either the main CPU 143 or the sub CPU 144. Thereby, the operational safety of the circulation pump 300 with respect to controller abnormality improves.

  First, the control operation of the antifreezing control at the normal time will be described with reference to FIG. Under normal conditions, both the main CPU 143 and the sub CPU 144 are operating normally, and from all of the inflowing circulating fluid temperature sensor TWR, the outflowing circulating fluid temperature sensor TWL, the heat exchanger surface temperature sensor TWS, and the pressure sensor PL. A normal detection signal is input.

  In this case, the freeze prevention control described above is performed by the main CPU 143. Detection signals from the outflow circulating fluid temperature sensor TWL and the pressure sensor PL are directly input to the main CPU 143, and detection signals from the inflowing circulating fluid temperature sensor TWR and the heat exchanger surface temperature sensor TWS are input via the sub CPU 144. Entered. The main CPU 143 monitors the temperatures detected from these four signals, and performs the above-described antifreezing control when any of them falls below a predetermined temperature (for example, 2 ° C.).

  Specifically, the main CPU 143 controls the connection relay RY1 to supply power to the motor 301 and operate the circulation pump 300. Further, the main CPU 143 performs control for closing the gas valve GV. In this example, the gas valve GV is a valve that adjusts the fuel supply to the engine 60. By closing the gas valve GV, the engine 60 stops and the compressor 10 stops. The closing of the gas valve GV is an example of control for stopping the compressor 10, and the present invention is not limited to this. For example, when the drive source of the compressor 10 is an engine and the compressor 10 is stopped before the engine completely starts driving, control for stopping power supply to the starter of the engine may be performed. Or when the drive source of the compressor 10 is a motor, the control which stops the electric power feeding to this motor may be sufficient.

  Next, the control operation of the freeze prevention control when the main CPU 143 is abnormal will be described with reference to FIG. When the main CPU 143 is abnormal, detection signals from the outflow circulating fluid temperature sensor TWL and the pressure sensor PL input to the main CPU 143 cannot be detected. In this case, if the freeze prevention control is performed based only on the remaining detection signals, the circulating fluid may freeze due to incomplete control. For this reason, when the main CPU 143 is abnormal, the sub CPU 144 performs anti-freezing control regardless of the detection result of each sensor.

  In this case, the sub CPU 144 detects an abnormality of the main CPU 143 due to a communication error with the main CPU 143. When the sub CPU 144 detects an abnormality in the main CPU 143, the sub CPU 144 controls the connection relay RY2 and the connection relay RY (MC) to supply power to the motor 301 and operate the circulation pump 300.

  Moreover, as control which stops the compressor 10, although sub CPU144 may perform control which closes the gas valve GV, the case where auxiliary CPU147 performs this control is illustrated here. That is, the auxiliary CPU 147 can detect an abnormality of the main CPU 143 by a communication error with the main CPU 143. When the auxiliary CPU 147 detects an abnormality in the main CPU 143, the auxiliary CPU 147 closes the gas valve GV and stops the compressor 10.

  Next, the control operation of the freeze prevention control when the sensor input to the main CPU 143 is abnormal will be described with reference to FIG. The sensor input abnormality to the main CPU 143 is when the outflow circulating fluid temperature sensor TWL or the pressure sensor PL is abnormal and the detection signal is not output, or the detection signal of these sensors is input to the main CPU 143 due to the disconnection of the signal line. It refers to the case where it is no longer done. Also in this case, if the freeze prevention control is performed based only on the incomplete sensor input, the circulation fluid may be frozen due to the incomplete control. For this reason, the main CPU 143 performs the following freeze prevention control regardless of the detection result of each sensor.

  When the detection signal of the outflow circulating fluid temperature sensor TWL or the pressure sensor PL is no longer input to the main CPU 143, the main CPU 143 detects a sensor input abnormality. The main CPU 143 that has detected the sensor input abnormality controls the connection relay RY1 to operate the circulation pump 300 and closes the gas valve GV to stop the compressor 10.

  Next, the control operation of the freeze prevention control when the sub CPU 144 is abnormal will be described with reference to FIG. When the sub CPU 144 is abnormal, detection signals from the inflowing circulating fluid temperature sensor TWR and the heat exchanger surface temperature sensor TWS input to the sub CPU 144 cannot be detected. In this case, if the freeze prevention control is performed based only on the remaining detection signals, the circulating fluid may freeze due to incomplete control. For this reason, when the sub CPU 144 is abnormal, the main CPU 143 performs anti-freezing control regardless of the detection result of each sensor.

  In this case, the main CPU 143 detects an abnormality in the sub CPU 144 based on a communication error with the sub CPU 144. When the main CPU 143 detects an abnormality in the sub CPU 144, the main CPU 143 controls the connection relay RY1 to operate the circulation pump 300, and closes the gas valve GV to stop the compressor 10.

  Next, the control operation of the freeze prevention control when the sensor input to the sub CPU 144 is abnormal will be described with reference to FIG. Abnormal sensor input to the sub CPU 144 means that the detection signal is not output due to an abnormality in the inflowing circulating fluid temperature sensor TWR or the heat exchanger surface temperature sensor TWS, or the detection signal of these sensors is due to the disconnection of the signal line. This indicates a case where the input to the sub CPU 144 is stopped. Also in this case, if the freeze prevention control is performed based only on the incomplete sensor input, the circulation fluid may be frozen due to the incomplete control. For this reason, the main CPU 143 performs the following freeze prevention control regardless of the detection result of each sensor.

  When detection signals from the inflowing circulating fluid temperature sensor TWR or the heat exchanger surface temperature sensor TWS are not input to the sub CPU 144, these detection signals are not input to the main CPU 143 as well. Thereby, the main CPU 143 detects a sensor input abnormality. The main CPU 143 that has detected the sensor input abnormality controls the connection relay RY1 to operate the circulation pump 300 and closes the gas valve GV to stop the compressor 10.

  In addition, the chiller 100 according to the present embodiment has a function of detecting whether there is an abnormality in the inflowing circulating fluid temperature sensor TWR, the outflowing circulating fluid temperature sensor TWL, the heat exchanger surface temperature sensor TWS, and the pressure sensor PL at the time of starting. Have This sensor abnormality detection operation will be described with reference to FIG. That is, when the chiller 100 is activated, the control device 140 performs the operation shown in the flowchart of FIG. 8 in order to detect the presence or absence of sensor abnormality.

  When the chiller 100 is activated, the control device 140 first detects an abnormality in the outflow circulating fluid temperature sensor TWL and the pressure sensor PL (ST1). That is, the control device 140 has a self-check function for detecting an abnormality in the signal itself received by the main CPU 143 for the outflow circulating fluid temperature sensor TWL and the pressure sensor PL that input signals to the main CPU 143. Abnormalities in the outflow circulating fluid temperature sensor TWL and the pressure sensor PL in this case are detected by the main CPU 143. This abnormality detection can be determined, for example, by confirming the presence / absence of detection signals in the outflow circulating fluid temperature sensor TWL and the pressure sensor PL and whether the signal value is within a specified range. Specifically, when there is no detection signal or when there is a signal but not within a specified range, it can be determined that the sensor is abnormal. If there is no abnormality in outflow circulating fluid temperature sensor TWL and pressure sensor PL (YES in ST1), the process proceeds to ST2, and if there is an abnormality, YES in ST1, the process proceeds to ST5. It is assumed that the compressor 10 is not driven until sensor abnormality detection is completed.

  In ST2, the control device 140 acquires the detected temperature from each of the inflowing circulating fluid temperature sensor TWR, the outflowing circulating fluid temperature sensor TWL, and the heat exchanger surface temperature sensor TWS.

  Next, the control device 140 obtains a detected temperature difference between the inflowing circulating fluid temperature sensor TWR and the outflowing circulating fluid temperature sensor TWL, and the absolute value of the temperature difference is not less than a first predetermined value (for example, 2.0 ° C.). Whether or not is determined (ST3). Immediately after the start of the chiller 100, the circulating fluid is neither cooled nor heated, so it is considered that there is almost no difference between the detected temperature of the inflowing circulating fluid temperature sensor TWR and the detected temperature of the outflowing circulating fluid temperature sensor TWL. Therefore, in ST3, when the temperature difference is equal to or higher than the predetermined temperature (YES in ST3), it is determined that the inflowing circulating fluid temperature sensor TWR is abnormal, and the process proceeds to ST5.

  In ST3, when the temperature difference is less than 2.0 (NO in ST3), control device 140 obtains a detected temperature difference between outflow circulating fluid temperature sensor TWL and heat exchanger surface temperature sensor TWS, and It is determined whether or not the absolute value of the temperature difference is equal to or greater than a second predetermined value (> first predetermined value; for example, 3.0 ° C.) (ST4). If the temperature difference is equal to or higher than the predetermined temperature in ST4 (YES in ST4), it is determined that there is an abnormality in the heat exchanger surface temperature sensor TWS, and the process proceeds to ST5.

  In ST5, the control device 140 closes the gas valve GV to stop the compressor 10 (that is, does not start driving the compressor 10), starts the operation of the circulation pump 300, and causes an abnormality in the sensor. An alarm is sent to inform you that the In ST4, when the temperature difference is less than the predetermined temperature (NO in ST4), there is no abnormality in all the sensors, so that the process proceeds to ST6 and the operation of the chiller 100 is started.

  Thus, the reliability of the anti-freezing detection is improved by confirming whether the temperature sensor is abnormal before driving the compressor 10.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Compressor 20 Refrigerant-air heat exchanger 30 Refrigerant-air heat exchanger fan 40 Expansion valve 50 Refrigerant-circulating liquid heat exchanger 60 Engine 100 Heat pump chiller 110 Refrigerant circuit 140 Controller 143 Main CPU (first controller)
144 Sub CPU (second controller)
147 Auxiliary CPU
200 Circulating fluid circuit 211 Inflow pipe 212 Outflow pipe 300 Circulating pump TWR Inflowing circulating fluid temperature sensor TWL Outflow circulating fluid temperature sensor TWS Heat exchanger surface temperature sensor PL Pressure sensor GV Gas valve RY1 Connection relay (first connection relay)
RY2 connection relay (second connection relay)
RY (MC) connection relay (second connection relay)

Claims (3)

A compressor for sucking and discharging refrigerant, a refrigerant-air heat exchanger, an expansion valve, and a refrigerant-circulating liquid heat exchanger for exchanging heat between the circulating liquid and the refrigerant, and a circulation pump provided in the flow path of the circulating liquid In heat pump chiller,
A temperature sensor is provided for each of the circulating fluid inlet, the circulating fluid outlet, and the surface of the refrigerant-circulating fluid heat exchanger, and a pressure sensor is provided for the refrigerant suction path of the compressor,
When it is detected that any one of the temperature detected by the three temperature sensors or the refrigerant evaporation temperature converted from the pressure detected by the pressure sensor is equal to or lower than a predetermined temperature, the compressor is stopped, Operating the circulation pump ,
When starting the chiller, operate the circulation pump before driving the compressor,
After the operation of the circulating pump and before the start of driving of the compressor, the temperature difference between the temperature detected by the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the temperature detected by the temperature sensor at the circulating fluid outlet The absolute value is a first predetermined value or more, or the absolute value of the temperature difference between the temperature detected by the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the temperature detected by the surface temperature sensor is the first predetermined value. The heat pump chiller is characterized by stopping the driving of the compressor when it is detected that the second predetermined value is greater than the second predetermined value . In the heat pump chiller according to claim 1,
A plurality of controllers receive the detection signals of the three temperature sensors and the pressure sensor in a distributed manner,
The first controller receives signals from the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the pressure sensor at the refrigerant suction path of the compressor, and the circulating fluid outlet of the refrigerant-circulating fluid heat exchanger The second controller receives the temperature sensor signal of the surface portion and the surface portion,
The first controller has a function of detecting an abnormality of a received signal itself, and is a heat pump chiller. A compressor for sucking and discharging refrigerant, a refrigerant-air heat exchanger, an expansion valve, and a refrigerant-circulating liquid heat exchanger for exchanging heat between the circulating liquid and the refrigerant, and a circulation pump provided in the flow path of the circulating liquid In heat pump chiller,
A temperature sensor is provided for each of the circulating fluid inlet, the circulating fluid outlet, and the surface of the refrigerant-circulating fluid heat exchanger, and a pressure sensor is provided for the refrigerant suction path of the compressor,
When it is detected that any one of the temperature detected by the three temperature sensors or the refrigerant evaporation temperature converted from the pressure detected by the pressure sensor is equal to or lower than a predetermined temperature, the compressor is stopped, Operating the circulation pump,
A plurality of controllers receive the detection signals of the three temperature sensors and the pressure sensor in a distributed manner,
The first controller receives signals from the temperature sensor at the circulating fluid inlet of the refrigerant-circulating fluid heat exchanger and the pressure sensor at the refrigerant suction path of the compressor, and the circulating fluid outlet of the refrigerant-circulating fluid heat exchanger The second controller receives the temperature sensor signal of the surface portion and the surface portion,
A connection relay that is opened and closed by the first controller, a first connection relay provided between the circulation pump and a power source, and a connection relay that is opened and closed by the second controller, the circulation pump and the power source A heat pump chiller characterized in that a second connection relay provided in between is provided in parallel.

Images