JP6907110B2 - Heat pump device - Google Patents

Description

The present invention relates to a heat pump device that performs a defrosting operation for melting frost in an air heat exchanger.

Conventionally, this type has a heat pump circuit in which a compressor, a four-way valve, a liquid refrigerant heat exchanger, an expansion valve, and an air heat exchanger are connected by a refrigerant pipe, and in the liquid refrigerant heat exchanger, the refrigerant and the circulating liquid are exchanged. Some perform a heating operation in which heat is exchanged and the circulating liquid heated by the heat exchange is supplied to a heat exchange terminal such as a floor heating panel to heat the space to be air-conditioned. Depending on the conditions such as the size of the heating load and the size of the heating load, the air heat exchanger may frost, and if the air heat exchanger frosts, the heat exchange efficiency will decrease, so it is necessary to defrost the air heat exchanger. be. In this case, the four-way valve is switched so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, and the refrigerant discharged from the compressor is directly supplied to the air heat exchanger to be the air heat exchanger. There was a so-called reverse cycle defrosting operation that melts the frost generated in the air. (See, for example, Patent Document 1.)

Japanese Unexamined Patent Publication No. 2016-156602

By the way, in this conventional one, when the reverse cycle defrosting operation is started, the refrigerant that had been in the air heat exchanger until then goes around the expansion valve side and flows into the liquid refrigerant heat exchanger. However, the air heat exchanger functions as an evaporator during the heating operation before the start of the reverse cycle defrosting operation, and the refrigerant temperature in the air heat exchanger at this time is lower than the outside air temperature, and the air heat exchanger is When frost is formed, the temperature of the refrigerant in the air heat exchanger is in the negative range.

The reverse cycle defrosting operation is started in the above state, but when the reverse cycle defrosting operation is started, the refrigerant in the minus range temperature held in the air heat exchanger becomes a liquid refrigerant. As it flows into the heat exchanger, the liquid refrigerant heat exchanger is cooled rapidly, and the circulating liquid that has been heat-exchanged with the refrigerant in the negative range temperature in the liquid refrigerant heat exchanger may freeze, and the circulating liquid may freeze. There was a risk of damage to the liquid refrigerant heat exchanger due to freezing.

In order to solve the above problems, in claim 1, the present invention includes a compressor for compressing the refrigerant, a flow path switching means, a liquid refrigerant heat exchanger for heat exchange between the circulating liquid and the refrigerant, and an expansion valve. A heat pump circuit that has an air heat exchanger that exchanges heat between the outside air and the refrigerant, and circulates the circulating liquid in the liquid refrigerant heat exchanger and the liquid refrigerant heat exchanger. A circulation circuit having a pump and circulating the circulating liquid, an outside air temperature detecting means for detecting the outside air temperature, and a control device for controlling the operation are provided, and the heat pump circuit is operated and the circulation pump is driven. In the heat pump device that performs the heating operation to heat the circulating liquid, when the control device executes the defrosting operation to melt the frost generated in the air heat exchanger during the heating operation, the flow of the refrigerant The flow path switching means is controlled so that the direction is the same as the flow direction of the refrigerant during the heating operation, and the opening degree of the expansion valve is expanded as compared with that during the heating operation to circulate the refrigerant. After the normal cycle defrosting operation is executed for a predetermined time set longer as the outside air temperature detected by the outside air temperature detecting means is lower, the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation. The flow path switching means is switched so as to execute the reverse cycle defrosting operation for circulating the refrigerant, and the predetermined defrosting end condition is satisfied during the execution of the reverse cycle defrosting operation. Then, the reverse cycle defrosting operation is terminated and the heating operation is restarted, and the predetermined time is required to raise the temperature of the refrigerant in the air heat exchanger to a temperature at which the circulating fluid does not freeze. The time was set in advance.

Further, in claim 2, the circulation pump is driven at the maximum rotation speed during the reverse cycle defrosting operation.

According to claim 1 of the present invention, when the control device executes the defrosting operation during the heating operation, the flow path switching means so that the flow direction of the refrigerant is the same as the flow direction of the refrigerant during the heating operation. After performing a normal cycle defrosting operation in which the refrigerant is circulated by expanding the opening of the expansion valve compared to the heating operation, the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation. By switching the flow path switching means so as to execute the reverse cycle defrosting operation in which the refrigerant is circulated, the refrigerant temperature is the highest among the refrigerants circulating in the heat pump circuit by the normal cycle defrosting operation. The minimum temperature value of the refrigerant in the low air heat exchanger is raised to a temperature at which the circulating fluid does not freeze, and then the reverse cycle defrosting operation is performed. Therefore, during the reverse cycle defrosting operation, the refrigerant flows out of the air heat exchanger and expands. Even if the refrigerant flowing from the valve side flows into the liquid refrigerant heat exchanger, the circulating liquid in the liquid refrigerant heat exchanger will not freeze, and the liquid refrigerant heat exchanger will not be damaged due to the freezing of the circulating liquid. Is.

Further, according to claim 1, when the defrosting operation is executed, the lower the outside air temperature detected by the outside air temperature detecting means, the longer the time for executing the positive cycle defrosting operation is made. This is because the refrigerant in the air heat exchanger absorbs heat from the outside air during the heating operation, and the lower the outside air temperature, the lower the refrigerant temperature in the air heat exchanger. The circulating liquid in the liquid refrigerant heat exchanger does not freeze by performing the positive cycle defrosting operation as the defrosting operation with the lowest temperature value of the refrigerant in the air heat exchanger having the lowest refrigerant temperature. This is due to the change in the time required to raise the temperature. Therefore, by making the length of time for executing the positive cycle defrosting operation longer as the outside air temperature is lower, the positive cycle is equal to the time corresponding to the refrigerant temperature in the air heat exchanger corresponding to the outside air temperature. Since the defrosting operation is performed, the lowest temperature value of the refrigerant in the air heat exchanger, which has the lowest refrigerant temperature among the refrigerants circulating in the heat pump circuit during the heating operation, is set to the temperature at which the circulating fluid does not freeze in the positive cycle defrosting operation. When the reverse cycle defrosting operation is performed after the normal cycle defrosting operation, the refrigerant at a temperature that freezes the circulating liquid does not flow into the liquid refrigerant heat exchanger. It is a thing.

Further , according to claim 2 , during the reverse cycle defrosting operation, the heat on the circulation circuit side is transferred from the circulating liquid side to the refrigerant side via the liquid refrigerant heat exchanger by driving the circulation pump at the maximum rotation speed. It can be positively applied to the air heat exchanger and used for defrosting, and the time during which the defrosting operation is performed can be shortened.

The schematic block diagram of the heat pump apparatus of one Embodiment of this invention. The schematic block diagram explaining the operation in the heating operation and the normal cycle defrosting operation of a heat pump device. The schematic block diagram explaining the operation at the time of the reverse cycle defrosting operation of a heat pump apparatus. A time chart showing the operation when the defrosting operation is executed during the heating operation of the heat pump device. The figure which shows the correspondence relationship between the outside air temperature and a predetermined time.

Next, the configuration of the heat pump device according to the embodiment of the present invention will be described in detail with reference to the drawings. Although this heat pump device can function as a heating device and a cooling device, the components and operations when the heat pump device is mainly used as a heating device will be described in the following embodiments.

Reference numeral 1 denotes a heat pump unit as a heat pump type heat source machine for supplying a heated circulating fluid. The heat pump unit 1 is a compressor 2 having a variable rotation speed for compressing a refrigerant in its housing, and four sides as a flow path switching means. A valve 3, a liquid refrigerant heat exchanger that exchanges heat between the refrigerant and the circulating fluid, an expansion valve 5 as a depressurizing means, and an air heat exchanger that exchanges heat with the air (outside air) sent by the operation of the blower fan 6. 7 and 7 are connected in a ring shape by a refrigerant pipe 8 to form a heat pump circuit 9 in which a refrigerant circulates. The liquid refrigerant heat exchanger 4 is composed of, for example, a plate type heat exchanger. In the plate type heat exchanger, a plurality of heat transfer plates are laminated, and a refrigerant flow path through which a refrigerant flows and a liquid through which a circulating liquid flows. The flow paths are formed alternately with each heat transfer plate as a boundary. As the refrigerant that circulates in the heat pump circuit 9, any refrigerant such as an HFC refrigerant or a carbon dioxide refrigerant can be used.

Reference numeral 10 denotes an outside air temperature sensor that detects the outside air temperature, and reference numeral 11 denotes a refrigerant temperature sensor that is provided in the refrigerant pipe 8 from the expansion valve 5 to the air heat exchanger 7 and detects the refrigerant temperature.

The four-way valve 3 provided in the refrigerant pipe 8 has a function of switching the flow direction of the refrigerant in the heat pump circuit 9, and uses the refrigerant discharged from the compressor 2 as a liquid refrigerant heat exchanger 4, an expansion valve 5, and air. The air heat exchanger allows the refrigerant discharged from the compressor 2 to be circulated in the order of the heat exchanger 7 to form a flow path for returning to the compressor 2 (during the heating operation and the state during the normal cycle defrosting operation). It is possible to switch to a state in which the expansion valve 5 and the liquid refrigerant heat exchanger 4 are circulated in this order to form a flow path for returning to the compressor 2 (state during reverse cycle defrosting operation).

Reference numeral 12 denotes a heat exchange terminal to which the circulating liquid heated by the heat pump unit 1 is supplied and air-conditioning the air-conditioned space by utilizing the heat of the supplied circulating liquid. The heat exchange terminal 12 is a dedicated heating terminal. A certain floor heating panel, radiator, radiation panel, fan coil, etc., which are terminals for both heating and cooling, are used. Although only one is provided in FIG. 1, a plurality of them may be provided, and the quantity and specifications are not particularly limited.

Reference numeral 13 denotes a circulation circuit in which the liquid refrigerant heat exchanger 4 and the heat exchange terminal 12 are connected in a ring shape by a liquid pipe 14 to circulate the circulating liquid (for example, water, antifreeze liquid, etc.). A circulation pump 15 having a variable rotation speed for circulating the circulating fluid, a return temperature sensor 16 for detecting the temperature of the circulating fluid flowing into the liquid refrigerant heat exchanger 4 from the heat exchange terminal 12, and a circulation circuit 13 for storing the circulating fluid. It is equipped with a systurn 17 that adjusts the pressure of the.

Reference numeral 18 denotes a control device including a storage means for storing various data and programs and a control means for performing calculation / control processing, and controlling the operation of the heat pump device. The control device 18 is a control device for various sensors in the heat pump unit 1. It receives a signal or a signal from the remote control 19 and controls the drive of the compressor 2, the four-way valve 3, the expansion valve 5, the blower fan 6, and the circulation pump 15.

The control device 18 operates the heat pump circuit 9 and drives the circulation pump 15, heats the circulating liquid in the liquid refrigerant heat exchanger 4, supplies the heated circulating liquid to the heat exchange terminal 12, and is air-conditioned. During the heating operation for heating the space, if it is determined that the predetermined defrosting start condition is satisfied, the defrosting operation for melting the frost of the air heat exchanger is executed.

When the control device 18 determines that the predetermined defrosting start condition is satisfied during the heating operation, the refrigerant flow during the heating operation is performed as the defrosting operation without changing the flow direction of the refrigerant from the heating operation. After executing a normal cycle defrosting operation in which the direction is the same as the direction and the refrigerant is circulated to melt the frost generated in the air heat exchanger 7, the flow direction of the refrigerant becomes opposite to the flow direction of the refrigerant during the heating operation. By switching the four-way valve 3 as described above, the high-temperature refrigerant discharged from the compressor 2 is directly circulated to the air heat exchanger 7 to execute a reverse cycle defrosting operation for melting the frost generated in the air heat exchanger 7. It is a thing. The detailed operation of the defrosting operation will be described later.

Further, the start of the defrosting operation is, for example, whether or not the outside air temperature detected by the outside air temperature sensor 10 has reached a preset defrosting start temperature, or the outside air temperature and the refrigerant temperature detected by the outside air temperature sensor 10. The control device 18 determines whether or not the refrigerant temperature detected by the sensor 11 has reached the preset defrosting start temperature, that is, the control device 18 determines whether or not the predetermined defrosting start condition is satisfied. Then, when it is determined that the defrosting start condition is satisfied, the defrosting operation can be started. Further, when the defrosting operation is completed, the control device 18 determines whether or not the temperature of the refrigerant flowing through the air heat exchanger 7 detected by the refrigerant temperature sensor 11 has reached a preset defrosting end temperature. The control device 18 determines whether or not the predetermined defrosting end condition is satisfied, and if it is determined that the defrosting end condition is satisfied, the defrosting operation can be terminated.

Next, the operation of the heat pump device during the heating operation will be described with reference to FIG. The arrow lines in FIG. 2 indicate the flow direction of the refrigerant flowing through the heat pump circuit 9, and the flow direction of the circulating liquid flowing through the circulation circuit 13, respectively. Although the heat pump device of the present embodiment can perform the cooling operation, only the operation during the heating operation will be described here, and the description of the cooling operation will be omitted.

When the remote control 19 gives an instruction for a heating operation in which the liquid refrigerant heat exchanger 4 heats the circulating liquid and supplies it to the heat exchange terminal 12, the control device 18 causes the four-way valve 3 to be in the state during the heating operation. The flow path is switched, the compressor 2, the expansion valve 5, and the blower fan 6 are driven to operate the heat pump circuit 9, and the circulation pump 15 is driven to start the heating operation. 3. Liquid refrigerant heat exchanger 4, expansion valve 5, air heat exchanger 7, four-way valve 3, compressor 2 circulate in this order (see the arrow in heat pump circuit 9 in FIG. 2), and the circulating liquid is liquid refrigerant. It is circulated from the heat exchanger 4 to the heat exchange terminal 12 and returned from the heat exchange terminal 12 to the liquid refrigerant heat exchanger 4 again (see the arrow line in the circulation circuit 13 in FIG. 2). At this time, the liquid refrigerant heat exchanger 4 functions as a condenser, and the air heat exchanger 7 functions as an evaporator.

The control device 18 sets the rotation speed of the compressor 2 so that the detection value of the return temperature sensor 16 that detects the temperature of the circulating fluid during the heating operation becomes the target temperature set based on the set temperature of the remote controller 19. It controls.

During the heating operation, in the heat pump circuit 9, the liquid refrigerant heat exchanger 4 functions as a condenser, and the high temperature and high pressure vapor phase refrigerant discharged from the compressor 2 in the liquid refrigerant heat exchanger 4 and the circulation pump 15 The circulating liquid is heat-exchanged with the circulating liquid circulated by the refrigerant, and the circulating liquid is heated by the heat of the refrigerant. On the other hand, the air heat exchanger 7 functions as an evaporator, and is blown by driving the low-temperature low-pressure gas-liquid two-phase state refrigerant discharged from the expansion valve 5 and the blower fan 6 by the air heat exchanger 7. The heat is exchanged with the outside air, the refrigerant absorbs heat from the outside air, changes to the gas phase state, and returns to the compressor 2.

Further, during the heating operation, in the circulation circuit 13, the circulating liquid heated by the liquid refrigerant heat exchanger 4 is supplied to the heat exchange terminal 12 by the drive of the circulation pump 15 and dissipates heat to the inside air of the air-conditioned space. The air-conditioned space is heated, and the circulating liquid flowing out of the heat exchange terminal 12 is returned to the liquid refrigerant heat exchanger 4 and heated.

If the control device 18 determines that the predetermined defrosting start condition is satisfied during this heating operation, the execution of the defrosting operation is started. As the defrosting operation, first, the normal cycle defrosting operation is performed for a predetermined time. conduct. As shown in FIG. 2, the mode of the normal cycle defrosting operation is a mode in which the refrigerant is circulated in the same direction as during the heating operation (see the arrow line of the heat pump circuit 9 in FIG. 2), and a specific normal cycle defrosting operation is performed. As an operation of the frost operation, the control device 18 controls the rotation speed of the compressor 2 to a preset rotation speed at the time of defrosting, and the expansion valve 5 has a predetermined opening degree as compared with the heating operation before the defrosting operation. The number of revolutions of the circulation pump 15 is set to a preset number of revolutions during defrosting. At this time, the high-temperature refrigerant discharged from the compressor 2 exchanges heat with the circulating liquid in the liquid refrigerant heat exchanger 4, flows out of the liquid refrigerant heat exchanger 4, passes through the expansion valve 5, and is an air heat exchanger. It is supplied to the air heat exchanger 7 to defrost the air heat exchanger 7. During this positive cycle defrosting operation, the expansion valve 5 expands by expanding the opening degree to a predetermined opening degree. In the valve 5, the refrigerant passes through without being depressurized, the refrigerant is supplied to the air heat exchanger 7 while being warm, and the frost generated in the air heat exchanger 7 is melted.

When the forward cycle defrosting operation is performed for a predetermined time, the reverse cycle defrosting operation is then started as the defrosting operation. In the reverse cycle defrosting operation, as shown in FIG. 3, the refrigerant is used as a compressor 2, a four-way valve 3, an air heat exchanger 7, an expansion valve 5, a liquid refrigerant heat exchanger 4, a four-way valve 3, and a compressor. It is a form in which the refrigerant is circulated in the order of 2 and the refrigerant is circulated in the direction opposite to that during the heating operation (see the arrow line of the heat pump circuit 9 in FIG. 3). 18 switches the four-way valve 3 so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, and controls the rotation speed of the compressor 2 to the same rotation speed during defrosting as in the normal cycle defrosting operation. At the same time, the expansion valve 5 is fully opened and the circulation pump 15 is driven at the maximum rotation speed. At this time, the high-temperature refrigerant discharged from the compressor 2 is directly supplied to the air heat exchanger 7 to melt the frost generated in the air heat exchanger 7. The low-temperature refrigerant that has dropped in temperature due to heat exchange with frost in the air heat exchanger 7 and has flowed out of the air heat exchanger 7 passes through the expansion valve 5 without being depressurized by the expansion valve 5, and is a liquid refrigerant heat exchanger. In No. 4, heat is exchanged with the circulating fluid, heat is absorbed from the circulating fluid, and the compressor returns to the compressor 2 again.

Next, as a characteristic operation, the time chart of FIG. 4 shows the operation of the heat pump device 1 when the defrosting operation for melting the frost generated in the air heat exchanger 7 is executed during the heating operation. It will be described using. The time t0 in FIG. 4 is an arbitrary time after the heating operation is stabilized.

The four-way valve 3 is controlled so that the refrigerant is a refrigerant flow path during heating operation in which the refrigerant circulates in the order of the compressor 2, the liquid refrigerant heat exchanger 4, the expansion valve 5, the air heat exchanger 7, and the compressor 2. 2. The expansion valve 5 and the blower fan 6 are driven, and the circulation pump 15 is driven. The liquid refrigerant heat exchanger 4 heat exchanges the refrigerant and the circulating liquid to heat the circulating liquid, and the heated circulating liquid. Is being supplied to the heat exchange terminal 12 to heat the air-conditioned space, and the control device 18 determines that the defrosting start condition is satisfied from the outside air temperature detected by the outside air temperature sensor 10. In this case (time t1), the control device 18 starts a positive cycle defrosting operation for a predetermined time as a defrosting operation for melting the frost generated in the air heat exchanger 7 (time t1 to). At this time, the control device 18 does not switch the flow path of the refrigerant in the four-way valve 3 and is in the same state as in the heating operation (the refrigerant is the compressor 2, the liquid refrigerant heat exchanger 4, the expansion valve 5, and the air heat exchanger 7). , The state of circulation in the order of the compressor 2) is controlled, the rotation speed of the compressor 2 is controlled to a preset rotation speed at the time of defrosting, and the expansion valve 5 is opened at a predetermined time as compared with the heating operation. It is controlled to expand to a degree, here to fully open, and the rotation speed of the circulation pump 15 is controlled to a preset rotation speed during defrosting, here the same rotation speed as during heating operation. The rotation speed of the circulation pump 15 during defrosting may be the same as that during the heating operation as described above, or may be a preset predetermined rotation speed during defrosting that is different from that during the heating operation.

During the positive cycle defrosting operation, the high-temperature refrigerant discharged from the compressor 2 exchanges heat with the circulating liquid in the liquid refrigerant heat exchanger 4 and dissipates heat to the circulating liquid, and flows out of the liquid refrigerant heat exchanger 4. Later, it passes through the expansion valve 5 and is supplied to the air heat exchanger 7, and the air heat exchanger 7 is defrosted. During this positive cycle defrosting operation, the opening degree of the expansion valve 5 is set to a predetermined value. By expanding to the fully open opening, the refrigerant passes through the expansion valve 5 without being depressurized, and the refrigerant flows out of the liquid refrigerant heat exchanger 4 with almost no temperature drop of the refrigerant when passing through the expansion valve 5. Is supplied to the air heat exchanger 7 to melt the frost generated in the air heat exchanger 7, and the expansion valve 5 is fully opened for a predetermined time by executing the normal cycle defrosting operation. By circulating the refrigerant in the heat pump circuit 9 during the time t1 to time t2), the expansion valve 5 whose temperature was low on the low pressure side during the heating operation was heated to the flow path of the refrigerant in the air heat exchanger 7. A refrigerant having a temperature higher than that during operation flows, whereby the flow path of the refrigerant of the air heat exchanger 7 is heated from the expansion valve 5 and the temperature gradually rises, and among the refrigerants circulating in the heat pump circuit 9, the refrigerant The lowest temperature value of the refrigerant in the air heat exchanger 7 having the lowest temperature (more accurately, the lowest temperature value of the refrigerant in the refrigerant flow path from the expansion valve 5 outlet to the air heat exchanger 7 outlet) is also, for example. The temperature gradually rises from -5 ° C to -2 ° C and from -2 ° C to 0 ° C.

Further, the positive cycle defrosting operation is performed for a predetermined time (time t1 to time t2), and this predetermined time is when the outside air temperature is −5 ° C. or higher and lower than 0 ° C. as shown in FIG. Is set to 1 minute when the outside air temperature is -10 ° C or more and less than -5 ° C, 3 minutes when the outside air temperature is less than -10 ° C, and 5 minutes when the outside air temperature is less than -10 ° C. The predetermined time is changed according to the outside air temperature detected by the outside air temperature sensor 10. Specifically, the lower the outside air temperature detected by the outside air temperature sensor 10, the longer the predetermined time. Is set longer. To explain this, first, the air heat exchanger 7 functions as an evaporator during the heating operation, and in the air heat exchanger 7, heat exchange is performed between the outside air and the refrigerant, and the refrigerant absorbs heat from the outside air. Above, the refrigerant temperature is lower than the outside air temperature, and the lower the outside air temperature, the lower the refrigerant temperature correspondingly. Then, in executing the positive cycle defrosting operation during the heating operation, the length of the predetermined time for executing the positive cycle defrosting operation is made uniform regardless of the outside air temperature, and the outside air temperature is, for example, -1 ° C. Comparing the state after the positive cycle defrosting operation between the case where the temperature was -10 ° C and the case where the temperature was -10 ° C, when the outside air temperature was -1 ° C, the air heat exchanger 7 was compared with the case where the outside air temperature was -10 ° C. Since the temperature of the refrigerant inside is high, as a result of the positive cycle defrosting operation for a predetermined time set uniformly, the lowest of the refrigerants in the air heat exchanger 7 having the lowest refrigerant temperature among the refrigerants circulating in the heat pump circuit 9 The temperature value also rises, and when the reverse cycle defrosting operation after the normal cycle defrosting operation is started, the temperature of the refrigerant flowing out of the air heat exchanger 7 and flowing into the liquid refrigerant heat exchanger 4 is determined. The temperature can be raised to a temperature at which the circulating liquid in the liquid refrigerant heat exchanger 4 is not frozen. On the other hand, when the outside air temperature is -10 ° C, the original refrigerant temperature is lower than when the outside air temperature is -1 ° C. When the reverse cycle defrosting operation after the cycle defrosting operation is started, the circulating liquid in the liquid refrigerant heat exchanger 4 cannot be raised to a temperature that does not freeze, and the circulating liquid may be frozen. There is.

Of the above comparative examples, it is conceivable to uniformly set the length of the predetermined time based on the lower outside air temperature (-10 ° C. in the above example), but in that case, when the outside air temperature is high (the above example). Then, at -1 ° C), the positive cycle defrosting operation is excessively performed, which causes unnecessary heat dissipation loss. Therefore, the length of the predetermined time is preferably set according to the outside air temperature, and the lower the outside air temperature, the longer the time for executing the positive cycle defrosting operation is set. The correspondence between the outside air temperature and the predetermined time shown in FIG. 5 is an example, but by conducting an experiment in advance, the refrigerant temperature among the refrigerants circulating in the heat pump circuit 9 at the end of the normal cycle defrosting operation is changed. The time during which the minimum temperature value of the refrigerant in the lowest air heat exchanger 7 can be raised to a temperature that does not freeze the circulating fluid is determined according to the outside air temperature, and the outside air temperature in FIG. 5 is determined. A data table showing the correspondence between the temperature and the predetermined time is stored in the control device 18 in advance. Further, the predetermined time is set by the control device 18 based on the outside air temperature detected by the outside air temperature sensor 10 at the timing (time t1) when it is determined that the defrosting start condition is satisfied.

Then, when the control device 18 determines that a predetermined time (time t1 to time t2) has elapsed from the start of execution of the normal cycle defrosting operation, the normal cycle defrosting operation is terminated, and then the air heat exchanger 7 is generated. The reverse cycle defrosting operation is started as the defrosting operation for melting the frost (time t2-). At this time, the control device 18 stops the drive of the compressor 2, and the refrigerant circulates through the four-way valve 3 in the order of the compressor 2, the air heat exchanger 7, the expansion valve 5, the liquid refrigerant heat exchanger 4, and the compressor 2. It is switched so that the refrigerant flow path is reversed from that during the heating operation (time t2). Further, the opening degree of the expansion valve 5 at this time is fully open, and the rotation speed of the circulation pump 15 maintains the rotation speed at the time of defrosting.

Then, the control device 18 eliminates the differential pressure between the discharge side (high pressure side) and the suction side (low pressure side) of the compressor 2 and takes time to safely start the functional parts such as the compressor 2 at the next startup. The compressor 2 is stopped for a certain period of time t2 to time t3, and then the rotation speed of the compressor 2 is set to a preset rotation speed at the time of defrosting to start driving, and the circulation pump 15 is operated at the maximum rotation speed. Drive (time t3 to time t4). At this time, the high-temperature refrigerant discharged from the compressor 2 is directly supplied to the air heat exchanger 7 to melt the frost generated in the air heat exchanger 7, and the refrigerant flowing out from the air heat exchanger 7 expands. It passes through the expansion valve 5 without being depressurized by the valve 5, exchanges heat with the circulating liquid in the liquid refrigerant heat exchanger 4, absorbs heat from the circulating liquid, and returns to the compressor 2 again.

During this reverse cycle defrosting operation, the refrigerant flowing out of the air heat exchanger 7 goes around the expansion valve 5 side and is circulated to the liquid refrigerant heat exchanger 4, but the positive cycle defrosting before the reverse cycle defrosting operation is executed. During operation, the minimum temperature value of the refrigerant is raised to a temperature at which the circulating liquid in the liquid refrigerant heat exchanger 4 is not frozen. Therefore, during the reverse cycle defrosting operation, the refrigerant flows out of the air heat exchanger 7 and the expansion valve 5 Even if the refrigerant flowing from the side flows into the liquid refrigerant heat exchanger 4, the circulating liquid in the liquid refrigerant heat exchanger 4 does not freeze, and the liquid refrigerant heat exchanger 4 may be damaged due to the freezing of the circulating liquid. There is no such thing.

Further, during the reverse cycle defrosting operation, by setting the rotation speed of the circulation pump 15 to the maximum rotation speed, the heat on the circulation circuit 13 side is positively transferred from the circulation liquid side to the refrigerant side via the liquid refrigerant heat exchanger 4. It can be used for defrosting the air heat exchanger 7 to shorten the time during which the defrosting operation is performed.

Then, when the reverse cycle defrosting operation is being performed, the control device 18 determines that the defrosting end condition is satisfied from the temperature of the refrigerant flowing through the air heat exchanger 7 detected by the refrigerant temperature sensor 11. , The drive of the compressor 2 is stopped, the rotation speed of the circulation pump 15 is controlled to be driven from the maximum rotation speed to the rotation speed at the time of defrosting (time t4), and the suction side (high pressure side) of the compressor 2 and the suction side. In order to eliminate the differential pressure on the side (low pressure side) and safely start the functional parts such as the compressor 2 at the next startup, the compressor 2 is stopped for a certain period of time t4 to time t5, and the reverse cycle defrosting operation is performed. After that, the control device 18 uses the four-way valve 3 as the compressor, the liquid refrigerant heat exchanger 4, the expansion valve 5, the air heat exchanger 7, and the compressor 2. The compressor is switched to the refrigerant flow path that circulates in order during the heating operation, the compressor 2 is started to be driven, and the opening degree of the expansion valve 5 is returned from the fully opened state to the opening degree during the heating operation. Is returned from the number of revolutions during defrosting to the number of revolutions during heating operation, and the heating operation is restarted (time t5).

As described above, in the present embodiment, when the defrosting start condition is satisfied during the heating operation, the normal cycle defrosting operation is executed for a predetermined time, and then the reverse cycle defrosting operation is performed. If the defrosting start condition is satisfied during the heating operation and the reverse cycle defrosting is suddenly performed, the low temperature refrigerant held in the air heat exchanger 7 that functioned as the evaporator during the heating operation. (Negative temperature refrigerant) flows from the air heat exchanger 7 to the liquid refrigerant heat exchanger 4 from the air heat exchanger 7 around the expansion valve 5 side without any temperature rise, and as a result, the liquid refrigerant heat exchanger. 4 is cooled rapidly, and the circulating liquid that has been heat-exchanged with the low-temperature refrigerant in the liquid refrigerant heat exchanger 4 may freeze, and the liquid refrigerant heat exchanger 4 may be damaged due to the freezing of the circulating liquid. However, since the normal cycle defrosting operation is executed for a predetermined time and then the reverse cycle defrosting operation is performed, the refrigerant temperature of the refrigerant circulating in the heat pump circuit 9 due to the positive cycle defrosting operation for a predetermined time. The lowest temperature value of the refrigerant in the air heat exchanger 7 is raised to a temperature at which the circulating fluid does not freeze, and then the reverse cycle defrosting operation is performed. Therefore, during the reverse cycle defrosting operation, the air heat exchanger 7 Even if the refrigerant flowing out from the expansion valve 5 and flowing into the liquid refrigerant heat exchanger 4 does not freeze, the circulating liquid in the liquid refrigerant heat exchanger 4 does not freeze, and the liquid refrigerant due to the freezing of the circulating liquid does not freeze. The heat exchanger 4 is not damaged. Further, the reverse cycle defrosting operation is performed after the normal cycle defrosting operation is executed for a predetermined time to raise the minimum temperature value of the refrigerant circulating in the heat pump circuit 9, so that the liquid refrigerant is operated during the reverse cycle defrosting operation. The temperature drop of the circulating fluid on the circulation circuit 13 side, which exchanges heat with the refrigerant in the heat exchanger 4, is reduced as compared with the case where only the reverse cycle defrosting operation is performed, and the deterioration of the heating feeling can be alleviated. Is.

Further, in the present embodiment, the length of the predetermined time for executing the positive cycle defrosting operation is made longer as the outside air temperature is lower, but this is because the refrigerant in the air heat exchanger 7 is used during the heating operation. Since heat is absorbed from the outside air, the lower the outside air temperature detected by the outside air temperature sensor 10, the lower the refrigerant temperature in the air heat exchanger 7. Therefore, among the refrigerants circulating in the heat pump circuit 9 during the heating operation, the refrigerant temperature is one. The time required to raise the minimum temperature value of the refrigerant in the lowest air heat exchanger 7 to a temperature value at which the circulating liquid in the liquid refrigerant heat exchanger 4 does not freeze by performing a positive cycle defrosting operation. It is due to change. Therefore, by making the length of the predetermined time for executing the positive cycle defrosting operation longer as the outside air temperature is lower, the time corresponding to the outside air temperature is adjusted to the refrigerant temperature in the air heat exchanger 7. Since the normal cycle defrosting operation is performed, the lowest temperature value of the refrigerant in the air heat exchanger 7 having the lowest refrigerant temperature among the refrigerants circulating in the heat pump circuit 9 during the heating operation is set to the circulating fluid by the normal cycle defrosting operation. Can be appropriately raised to a temperature at which the refrigerant does not freeze, and when the reverse cycle defrosting operation is performed after the normal cycle defrosting operation, the liquid refrigerant heat exchanger 4 is provided with a refrigerant having a temperature at which the circulating liquid freezes. It does not flow in.

Further, during the reverse cycle defrosting operation, the heat of the circulation circuit 13 side is positively transferred from the circulating liquid side to the refrigerant side via the liquid refrigerant heat exchanger 4 by driving the circulation pump 15 as the maximum rotation speed. It can be given as a target and used for defrosting the air heat exchanger 7, and the time during which the defrosting operation is performed can be shortened.

The present invention is not limited to the one embodiment described above. In the present embodiment, in the heat pump device that can be used not only as a heating device but also as a cooling device, the defrosting operation of the present invention is performed during the heating operation. However, in a heat pump device that can be used only as a heating device, the defrosting operation of the present invention may be applied during the heating operation.

Further, in the present embodiment, the normal cycle defrosting operation is executed for a predetermined time, and among the refrigerants circulating in the heat pump circuit 9 during the heating operation, the lowest temperature value of the refrigerant in the air heat exchanger 7 having the lowest refrigerant temperature. Was raised to a temperature at which the circulating fluid does not freeze by the normal cycle defrosting operation, and then the reverse cycle defrosting operation was performed. However, the refrigerant temperature sensor 11 detects the normal cycle defrosting operation. The normal cycle defrosting operation may be performed until the refrigerant temperature rises to a temperature at which the circulating fluid does not freeze, and then the reverse cycle defrosting operation may be performed. Similarly, by the positive cycle defrosting operation, the minimum temperature value of the refrigerant in the air heat exchanger 7, which has the lowest refrigerant temperature among the refrigerants circulating in the heat pump circuit 9, is raised to a temperature at which the circulating liquid does not freeze. Then, since the reverse cycle defrosting operation is performed, even if the refrigerant flowing out of the air heat exchanger 7 and flowing from the expansion valve 5 side flows into the liquid refrigerant heat exchanger 4 during the reverse cycle defrosting operation, the liquid refrigerant The effect that the circulating liquid in the heat exchanger 4 does not freeze and the liquid refrigerant heat exchanger 4 is not damaged due to the freezing of the circulating liquid can be exhibited.

2 Compressor 3 Four-way valve 4 Liquid refrigerant heat exchanger 5 Expansion valve 7 Air heat exchanger 9 Heat pump circuit 10 Outside air temperature sensor 13 Circulation circuit 15 Circulation pump 18 Control device

Claims (2)

A compressor for compressing the refrigerant, a flow path switching means, a liquid refrigerant heat exchanger for heat exchange between the circulating liquid and the refrigerant, an expansion valve, and an air heat exchanger for heat exchange between the outside air and the refrigerant. A heat pump circuit that has and circulates the refrigerant,
A circulation circuit having a liquid refrigerant heat exchanger and a circulation pump for circulating the circulating liquid in the liquid refrigerant heat exchanger, and circulating the circulating liquid.
Outside air temperature detecting means for detecting outside air temperature,
Equipped with a control device to control the operation
In a heat pump device that operates the heat pump circuit and drives the circulation pump to perform a heating operation for heating the circulating liquid.
When the control device executes a defrosting operation for melting the frost generated in the air heat exchanger during the heating operation, the flow direction of the refrigerant becomes the same as the flow direction of the refrigerant during the heating operation. The positive cycle defrosting operation in which the refrigerant is circulated by controlling the flow path switching means and expanding the opening degree of the expansion valve as compared with the heating operation is detected by the outside air temperature detecting means. The lower the outside air temperature, the longer the execution for a predetermined time, and then the flow path switching means is switched so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, so that the refrigerant is used. The reverse cycle defrosting operation to be circulated is executed, and when the predetermined defrosting end condition is satisfied during the execution of the reverse cycle defrosting operation, the reverse cycle defrosting operation is terminated and the heating operation is restarted. Let me
The heat pump device is characterized in that the predetermined time is predetermined as a time required to raise the temperature of the refrigerant in the air heat exchanger to a temperature at which the circulating fluid does not freeze. The heat pump device according to claim 1, wherein the circulation pump is driven at a maximum rotation speed during the reverse cycle defrosting operation.

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