JP7569713B2 - Heat pump equipment - Google Patents

Description

This invention relates to a heat pump device that performs heating operation by using heat received from a refrigerant to warm the circulating liquid to a load terminal.

Conventionally, in this type of heat pump device, as described in Patent Document 1, refrigerant is supplied from a heat pump device equipped with a compressor and a heat source side heat exchanger to a load side heat exchanger via a refrigerant pipe, and the circulating liquid to the load terminal is heated to perform heating. When temporarily stopping heating, some heat pump devices raise the circulating liquid temperature once (so-called hot charge) and then stop driving the heat source.

JP 2006-46700 A JP 2014-40954 A

In general, in this type of heat pump device, frost forms on the heat source side heat exchanger after a certain period of heating operation, and a defrosting operation is required to melt the frost.

For example, the technology described in the above Patent Document 1 does not specifically mention defrosting operation, but normally, the load side heat exchanger functions as an evaporator and the heat source side heat exchanger functions as a condenser. That is, from heating operation in which the discharge side of the compressor is connected to the load side heat exchanger as a condenser and the suction side of the compressor is connected to the heat source side heat exchanger as an evaporator by a switching valve (four-way valve), the compressor is stopped and the switching valve is switched to connect the discharge side of the compressor to the heat source side heat exchanger as a condenser and the suction side of the compressor to the load side heat exchanger as an evaporator. When the compressor is started after the switching, the refrigerant that has exchanged heat with the circulating liquid in the load side heat exchanger and evaporated is introduced to the compressor and compressed to a high temperature and high pressure, and then introduced to the heat source side heat exchanger to condense while releasing heat, and the heat released at this time can melt the frost that has formed as described above. In addition, if hot charging is performed as described above just before the compressor is stopped when starting the defrosting operation, the circulating fluid temperature can be kept relatively high during the defrosting operation, preventing a decrease in comfort in the heating environment.

When this defrosting operation is completed, the compressor is stopped and the switching valve is switched again, so that the discharge side of the compressor is connected to the load side heat exchanger and the suction side of the compressor is connected to the heat source side heat exchanger, as described above. By starting the compressor after this switching, heating operation can be resumed, as described above.

In general, the compressor speed when the defrosting operation is completed and the heating operation is resumed as described above is set to the same as the speed immediately before the defrosting operation was started, so that the circulating fluid is heated quickly. However, if the speed is set in this way when hot charging is performed immediately before the defrosting operation is started as described above, the heat accumulated in the circulating fluid piping, the load terminal, and the refrigerant piping causes the circulating fluid temperature to rise sharply and greatly exceed the target temperature when the heating operation is resumed after the defrosting operation is completed (overshoot). The compressor speed is usually temperature-controlled so that the actual circulating fluid temperature becomes a predetermined target temperature. As a result of the above-mentioned overshoot, the compressor stops and the heating operation stops, even though the heating operation should continue.

As described above, a technique for maintaining a relatively high circulating fluid temperature during defrosting operation to prevent a decrease in comfort in the heating environment includes providing a circulating fluid heating auxiliary means (auxiliary heater) in the circulating fluid piping through which the circulating fluid circulates, and heating the circulating fluid to the load terminal during defrosting operation, as described in Patent Document 2. Even with this method, if the compressor speed when the heating operation is resumed is set to the same as the speed immediately before the defrosting operation started, the heat accumulated in the circulating fluid piping and the load terminal during the defrosting operation can cause an overshoot similar to that described above, causing the heating operation to stop.

In order to solve the above problems, in claim 1 of the present invention, there is provided a heat pump mechanism in which a compressor, an expansion valve, and a heat source side heat exchanger are connected by refrigerant piping; a load side heat exchanger that receives refrigerant from the heat pump mechanism through the refrigerant piping and heats the circulating liquid to a load terminal by heat exchange with the circulating liquid; a first switching position that connects the discharge side of the compressor to the load side heat exchanger as a condenser and connects the suction side of the compressor to the heat source side heat exchanger as an evaporator; and a second switching position for connecting the intake side of the compressor to the load side heat exchanger as an evaporator; an actual temperature detection means for detecting an actual temperature of the circulating fluid; and a compressor control means including a temperature adjustment control means for controlling a rotation speed of the compressor so that the actual temperature detected by the actual temperature detection means becomes a predetermined target temperature, the heat pump device performing a heating operation in which the switching valve is switched to the first switching position and the circulating fluid to the load terminal is heated by using heat received from a refrigerant in the load side heat exchanger, a start determination means for determining whether a predetermined defrost start condition is satisfied in the defrost start control means, a defrost start control means for switching the switching valve to the second switching position and starting a defrosting operation of the heat source side heat exchanger by using heat received by the refrigerant in the load side heat exchanger after the start determination means has determined that the defrost start condition is satisfied, an end determination means for determining whether a predetermined defrost end condition is satisfied in the defrost start control means, and a start determination means for determining whether a predetermined defrost end condition is satisfied in the defrost start control means when the end determination means has determined that the defrost end condition is satisfied. and heating restart control means for switching the switching position to the first switch position and restarting the heating operation, wherein the compressor control means includes rotation speed adjustment means for adjusting a rotation speed Nt5 of the compressor at the time when the heating operation is restarted by the heating restart control means to a rotation speed Nt2-X that is lower by X than the rotation speed Nt2 of the compressor immediately before the start of the defrosting operation, and the rotation speed adjustment means determines X in response to the actual temperature of the circulating fluid detected by the actual temperature detection means after the heating operation is restarted, or the target temperature of the circulating fluid .

In addition, claim 2 further includes a target temperature correction means for correcting the target temperature of the circulating fluid to a higher value when the start determination means determines that the defrost start condition is satisfied, and the defrost start control means switches the switching valve to the second switching position to start the defrost operation after the actual temperature of the circulating fluid detected by the actual temperature detection means reaches the target temperature corrected to a higher value by the target temperature correction means.

In addition, in claim 3, a circulating fluid heating auxiliary means is provided in the circulating fluid piping through which the circulating fluid flows, and the circulating fluid is heated by this circulating fluid heating auxiliary means during the defrosting operation.

In addition, in claim 4 , the compressor control means adjusts the rotation speed of the compressor when the heating operation is resumed to Nt2-X based on the X determined by the rotation speed adjustment means, and when the actual temperature of the circulating fluid detected by the actual temperature detection means after the heating operation is resumed becomes lower than the target temperature by a predetermined value, the compressor control means controls the rotation speed of the compressor in accordance with a deviation between the actual temperature and a predetermined target temperature.

In order to solve the above problem, a fifth aspect of the present invention provides a heat pump mechanism in which a compressor, an expansion valve, and a heat source side heat exchanger are connected by refrigerant piping; a load side heat exchanger that receives refrigerant from the heat pump mechanism through the refrigerant piping and heats the circulating liquid to a load terminal by heat exchange with the circulating liquid; and a switching valve that is switchable between a first switching position where a discharge side of the compressor is connected to the load side heat exchanger serving as a condenser and a suction side of the compressor is connected to the heat source side heat exchanger serving as an evaporator, and a second switching position where the discharge side of the compressor is connected to the heat source side heat exchanger serving as a condenser and a suction side of the compressor is connected to the load side heat exchanger serving as an evaporator. a compressor control means including an actual temperature detection means for detecting an actual temperature of the circulating fluid, and a temperature regulation control means for controlling a rotation speed of the compressor so that the actual temperature detected by the actual temperature detection means becomes a predetermined target temperature, and the heat pump device performs a heating operation in which the changeover valve is switched to the first changeover position and the circulating fluid to the load terminal is heated by using heat received from the refrigerant in the load-side heat exchanger, the heat pump device further comprising a start determination means for determining whether or not a predetermined defrost start condition is satisfied during the heating operation, and a start determination means for determining whether or not the defrost start condition is satisfied after it is determined by the start determination means that the defrost start condition is satisfied, the start determination means for determining whether or not .... the defrost start control means for starting a defrosting operation of the heat source side heat exchanger, an end determination means for determining whether or not a predetermined defrost end condition is satisfied after the defrosting operation is started by the defrost start control means, and a heating restart control means for switching the changeover valve to the first changeover position and restarting the heating operation when it is determined by the end determination means that the defrost end condition is satisfied, the compressor control means includes a rotation speed adjustment means for adjusting the rotation speed of the compressor at the time of restarting the heating operation by the heating restart control means to a rotation speed lower than the rotation speed of the compressor immediately before the start of the defrosting operation, and the rotation speed adjustment means adjusts the rotation speed of the compressor at the time of restarting the heating operation by the heating restart control means to a rotation speed lower than the rotation speed of the compressor immediately before the start of the defrosting operation, The compressor control means adjusts the rotation speed of the compressor when the heating operation is resumed to a predetermined rotation speed according to the actual temperature of the circulating fluid detected by the actual temperature detection means after the heating operation is resumed or the target temperature of the circulating fluid, and the compressor control means adjusts the rotation speed of the compressor when the heating operation is resumed to the predetermined rotation speed by the rotation speed adjustment means, and controls the rotation speed of the compressor by the temperature adjustment control means in accordance with the deviation between the actual temperature of the circulating fluid detected by the actual temperature detection means and the actual temperature detected by the actual temperature detection means at the time the heating operation is resumed, when a predetermined threshold value is reached.

According to claim 1 of this invention, in the heat pump mechanism, the compressor, the expansion valve, and the heat source side heat exchanger are connected by refrigerant piping. During heating operation, the switching valve is switched to the first switching position, and the discharge side of the compressor is connected to the load side heat exchanger as a condenser, and the suction side of the compressor is connected to the heat source side heat exchanger as an evaporator. By starting the compressor in this state, the refrigerant that exchanges heat with the outside air in the heat source side heat exchanger and evaporates is led to the compressor and compressed to a high temperature and high pressure, and then led to the load side heat exchanger and condenses while releasing heat. This warms the circulating fluid, and the warmed circulating fluid is led to the load terminal to perform heating. At that time, the rotation speed of the compressor is controlled by the temperature control means provided in the compressor control means so that the actual temperature of the circulating fluid becomes a predetermined target temperature (so-called temperature control).

When the heating operation continues for a certain period of time, frost forms on the heat source side heat exchanger that exchanges heat with the outside air, and it is necessary to perform a defrosting operation to melt the frost. According to claim 1, the start determination means determines whether a predetermined defrosting operation start condition is satisfied. When the defrosting operation start condition is satisfied by the continuation of the heating operation, the defrosting start control means then switches the switching valve to the second switching position. This causes the discharge side of the compressor to communicate with the heat source side heat exchanger as a condenser, and the suction side of the compressor to communicate with the load side heat exchanger as an evaporator. By starting the compressor after this switching, the refrigerant that has exchanged heat with the circulating liquid in the load side heat exchanger and evaporated is introduced to the compressor and compressed to a high temperature and high pressure, and then introduced to the heat source side heat exchanger where it condenses while releasing heat, and the heat released at this time can melt the frost that has formed as described above.

Then, the end determination means determines whether or not a predetermined defrost end condition is met, and when the condition is met, the defrost operation ends, and the compressor is stopped, and the switching valve is switched again by the heating restart control means. That is, as described above, the discharge side of the compressor is connected to the load side heat exchanger, and the suction side of the compressor is connected to the heat source side heat exchanger. By starting the compressor after this switching, the heating operation can be resumed in the same manner as described above.

According to claim 1, the rotation speed Nt5 of the compressor when the heating operation is resumed is adjusted to Nt2-X by the rotation speed adjustment means provided in the compressor control means, which is lower by X than the rotation speed Nt2 of the compressor immediately before the start of the defrosting operation. This makes it possible to prevent overshooting of the circulating fluid temperature due to accumulated heat even if the circulating fluid temperature is kept high during the defrosting operation to prevent a decrease in comfort in the heating environment and heat is accumulated in the circulating fluid piping and the load terminals. As a result, the heating operation can be continued without stopping the compressor due to the temperature adjustment control by the temperature adjustment control means.
According to claim 1, when the rotation speed of the compressor at the time of restarting the heating operation is adjusted to be lower by X as described above in order to prevent the overshoot, the value of the rotation speed at the time of restart can be finely set in accordance with the actual temperature of the circulating fluid or the target temperature of the circulating fluid after the heating operation is restarted.

According to claim 2, when the defrosting operation start condition is satisfied by the continuation of the heating operation, the target temperature of the circulating fluid is corrected higher by the target temperature correction means. As a result, the rotation speed of the compressor increases due to the temperature control, so that heat can be accumulated in the circulating fluid pipe, the load terminal, and the refrigerant pipe before the compressor is stopped to start the defrosting operation (so-called hot charge). After that, when the actual temperature of the circulating fluid reaches the target temperature corrected higher by the target temperature correction means, the defrosting operation is started by the defrosting start control means. In this way, by performing hot charge just before the compressor is stopped at the start of the defrosting operation, the circulating fluid temperature during the defrosting operation can be reliably maintained relatively high, and a decrease in comfort in the heating environment can be reliably prevented.

According to claim 3, when the defrosting operation is performed, the circulating fluid heating auxiliary means provided in the circulating fluid piping heats the circulating fluid. This ensures that the circulating fluid temperature during the defrosting operation can be maintained relatively high, and the comfort of the heated environment can be prevented from decreasing.

According to claim 4 , after the value of the compressor rotation speed when the heating operation is restarted is set as described above, the set value can be maintained at least until the actual temperature of the circulating fluid becomes lower than the target temperature by a predetermined value, and then the original temperature adjustment control can be restored.

According to claim 5 of the present invention, after the value of the compressor rotation speed at the time of resuming the heating operation is set as described above, the set value can be maintained until the temperature deviation between the fluctuating actual temperature of the circulating fluid and the actual temperature of the circulating fluid at the time of resumption reaches a predetermined threshold value, and then the original temperature adjustment control can be restored.

FIG. 1 is an external configuration diagram of a main unit of a heat pump device according to an embodiment of the present invention. Overall circuit diagram of heat pump device Diagram explaining operation during heating operation Functional configuration diagram of the control device Diagram explaining operation during defrosting operation FIG. 1 is a time chart showing various behaviors in a comparative example in which the compressor rotation speed is not limited. FIG. 1 is a time chart showing various behaviors in an embodiment of the present invention in which the compressor rotation speed is limited. FIG. 1 is a flowchart showing a control procedure executed by a control device. FIG. 1 is an explanatory diagram showing a method for limiting the compressor rotation speed.

One embodiment of the present invention will be described below with reference to Figures 1 to 9.

The external configuration of the main units of a heat pump device 1 of this embodiment to which the present invention is applied is shown in FIG. 1. In FIG. 1, the heat pump device 1 of this embodiment has a heat pump unit 5 (corresponding to a heat pump mechanism) and a terminal circulation circuit 30 that circulates a circulating liquid L (e.g., water or antifreeze) to a heat exchange terminal 36 (corresponding to a load terminal).

The overall circuit configuration of the heat pump device 1 of this embodiment is shown in Figure 2. As shown in Figure 2, the heat pump device 1 has a refrigerant circulation circuit 50 that is provided in the heat pump unit 5 and can heat or cool the circulating liquid L on the heat exchange terminal 36 side by using an air heat source, and the terminal circulation circuit 30.

The refrigerant circulation circuit 50 includes a variable capacity compressor 53, a heat exchanger 51 as a load-side heat exchanger, an expansion valve 54, and an air heat exchanger 55 as a heat source-side heat exchanger, which are connected in a ring shape by refrigerant piping 52. The air heat exchanger 55 is provided with a blower fan 56 for blowing outside air through the air heat exchanger 55. The refrigerant piping 52 is also provided with a four-way valve 58 (corresponding to a switching valve) that switches the flow direction of refrigerant C2 (see Figures 3 and 5 described below) in the refrigerant circulation circuit 50.

The heat exchanger 51 is, for example, a plate-type heat exchanger, in which the refrigerant flow path for the refrigerant C2 and the fluid flow path for the circulating liquid L are alternately formed on each heat transfer plate.

The temperature of the refrigerant C2 discharged from the compressor 53 is detected by a refrigerant discharge temperature sensor 52a. Similarly, the refrigerant temperature on the low pressure side (when heating) or high pressure side (when cooling or defrosting) is detected by a refrigerant temperature sensor 52b provided in the refrigerant piping 52 from the expansion valve 54 to the air heat exchanger 55. In this embodiment, the temperature detected by the refrigerant temperature sensor 52b essentially functions as the refrigerant temperature in the air heat exchanger 55. Furthermore, the temperature of the outside air is detected by an outside air temperature sensor 57 as an outside air temperature detection means. The detection results of the refrigerant discharge temperature sensor 52a, the refrigerant temperature sensor 52b, and the outside air temperature sensor 57 are input to the control device 62.

The refrigerant C2 in the refrigerant circulation circuit 50 can be any refrigerant, such as an HFC refrigerant such as R410A or R32, or a carbon dioxide refrigerant.

In the terminal circulation circuit 30, the heat exchanger 51 and two heat exchange terminals 36A, 36B (hereinafter collectively referred to as "heat exchange terminals 36") such as fan coils, floor heating panels, and panel convectors are connected in a ring shape in order from the upstream side by the load piping 31 as a circulating liquid piping. In this example, the two heat exchange terminals 36 are connected in parallel to each other in the terminal circulation circuit 30 via an appropriate header (not shown). The load piping 31 is provided with a circulating liquid circulation pump 32 that circulates the circulating liquid L in the terminal circulation circuit 30, and a cistern 35 that stores the circulating liquid L and adjusts the pressure of the terminal circulation circuit 30. In FIG. 2, two heat exchange terminals 36 are provided in parallel, but one or three or more may be provided, and the number and specifications are not particularly limited.

The load pipe 31 is provided with a return liquid temperature sensor 34 as an actual temperature detection means for detecting the return temperature (corresponding to the actual temperature) of the circulating liquid L flowing from the heat exchange terminal 36 into the heat exchanger 51, and the detection result is input to the control device 62.

Here, the heat pump device 1 can selectively perform heating operation, cooling operation, or defrosting operation (details will be described later) by switching the four-way valve 58. Each operating mode will be described in order below.

<Heating operation>
3 shows the state during heating operation. During heating operation shown in FIG. 3, in the refrigerant circulation circuit 50, the four-way valve 58 is switched to the illustrated switching position (corresponding to the first switching position), so that the refrigerant C2 discharged from the compressor 53 flows through the heat exchanger 51, the expansion valve 54, and the air heat exchanger 55 in this order, and then returns to the compressor 53. As a result, the refrigerant C2 in a gas state sucked in at a low temperature and low pressure is compressed by the compressor 53 to become a high temperature and high pressure gas, and then in the heat exchanger 51 functioning as a condenser, it exchanges heat with the circulating liquid L flowing through the terminal circulation circuit 30, releasing heat to the circulating liquid L, and changing into a high pressure liquid while heating. The refrigerant C2 thus turned into a liquid is decompressed in the expansion valve 54 to become a low pressure liquid, which is in a state that is easy to evaporate, and in the air heat exchanger 55 functioning as an evaporator, it exchanges heat with the air sent by the operation of the blower fan 56, evaporates, and changes into a gas, absorbing heat, and returns to the compressor 53 again as a low temperature and low pressure gas.

In the terminal circulation circuit 30, the circulating liquid L sent by the circulating liquid circulation pump 32 is heated in the heat exchanger 51 by heat exchange with the refrigerant C2 that has been heated as described above by heat exchange with the outside air in the air heat exchanger 55. The heated circulating liquid L is then supplied to the heat exchange terminal 36 to heat the conditioned space.

<Cooling operation>
Although the above has been explained using heating operation as an example, when a terminal capable of cooling is used as the heat exchange terminal 36, the four-way valve 58 can be switched to form a flow path that circulates the refrigerant C2 discharged from the compressor 53 through the air heat exchanger 55, the expansion valve 54, and the heat exchanger 51 in that order, and then returns it to the compressor 53, thereby allowing cooling operation to be performed (detailed explanation is omitted).

<Control device>
Next, a description will be given of the control device 62. Although not shown in detail, the control device 62 includes a storage unit that stores various data and programs, and a control unit that performs calculation and control processing.

As shown in FIG. 4, the control device 62 functionally includes a compressor control unit 62A (corresponding to a compressor control means), an expansion valve control unit 62B, a fan control unit 62C, and a four-way valve control unit 62D. The control device 62 is also communicatively connected to the main remote control 60a (see FIG. 1 and FIG. 2).

The compressor control unit 62A controls the rotation speed of the compressor 53 according to the return hot water temperature (see FIG. 3) detected by the return liquid temperature sensor 34. In this example, a temperature adjustment control unit 62Aa (corresponding to a temperature adjustment control means) provided in the compressor control unit 62A performs temperature adjustment control, and the rotation speed of the compressor 53 is controlled according to the deviation between the return hot water temperature detected by the return liquid temperature sensor 34 and a desired target return hot water temperature (corresponding to a predetermined target temperature) corresponding to, for example, the operation of the main remote control 60a. In this particular example, the rotation speed of the compressor 53 is controlled by the temperature adjustment control unit 62Aa so that the return hot water temperature becomes the target return hot water temperature. The target temperature correction unit 62Ab and the rotation speed adjustment unit 62Ac will be described later.

The expansion valve control unit 62B controls the valve opening of the expansion valve 54 according to the refrigerant discharge temperature of the refrigerant C2 detected by the refrigerant discharge temperature sensor 52a. In this example in particular, the expansion valve control unit 62B controls the valve opening of the expansion valve 54 so that the refrigerant discharge temperature of the refrigerant C2 detected by the refrigerant discharge temperature sensor 52a becomes, for example, a desired target temperature for control.

The fan control unit 62C controls the rotation speed of the blower fan 56 according to the outside air temperature detected by the outside air temperature sensor 57.

The four-way valve control unit 62D receives an operation command (e.g., a control signal instructing the start and stop of heating operation, cooling operation, etc.) corresponding to the operation command issued by the main remote control 60a. The four-way valve control unit 62D also receives the outdoor air temperature detected by the outdoor air temperature sensor 57 and the refrigerant temperature of the refrigerant C2 detected by the refrigerant temperature sensor 52b. In response to these inputs, the four-way valve control unit 62D determines in what operating mode (cooling operation, heating operation, defrosting operation, etc.) the heat pump device 1 will actually be operated, and outputs the corresponding operating information to the compressor control unit 62A, the expansion valve control unit 62B, and the fan control unit 62C, and outputs a control signal corresponding to the determined operating mode to the four-way valve 58 to switch the four-way valve 58.

<Frost formation>
Here, when the heating operation continues for a certain period of time, frost forms in the air heat exchanger 55. In this embodiment, when frost forms in the air heat exchanger 55 during the heating operation in which the compressor 53 and the like are operating, the control device 62 performs a predetermined defrosting operation to melt the frost in the air heat exchanger 55.

<Defrosting operation>
5 shows the state during defrosting operation. In the refrigerant circulation circuit 50, the four-way valve 58 is switched to the illustrated switching position (corresponding to the second switching position), so that the inlet side of the air heat exchanger 55 is connected to the discharge side of the compressor 53, and the outlet side of the air heat exchanger 55 is connected to the inlet side of the heat exchanger 51 whose outlet side is connected to the suction side of the compressor 53. That is, a flow path is formed in which the refrigerant C2 discharged from the compressor 53 flows through the air heat exchanger 55, the expansion valve 54, and the heat exchanger 51 in this order, and then returns to the compressor 53. The refrigerant C2 in a gas state sucked in at a low temperature and low pressure is compressed by the compressor 53 to become a high-temperature and high-pressure gas, and then in the air heat exchanger 55 functioning as a condenser, it exchanges heat with the air sent by the operation of the blower fan 56, and changes into a high-pressure liquid while releasing heat. The heat at this time melts the frost in the air heat exchanger 55. The refrigerant C2 that has become liquid is reduced in pressure in the expansion valve 54 to become a low-pressure state that is easy to evaporate, and in the heat exchanger 51 that functions as an evaporator, it evaporates by exchanging heat with the circulating liquid L flowing through the terminal circulation circuit 30, and then returns to the compressor 53 again as a low-temperature, low-pressure gas.

At this time, in the terminal circulation circuit 30, the circulating liquid L that flows into the heat exchanger 51 by the circulating liquid circulation pump 32 exchanges heat with the low-pressure refrigerant C2 in the heat exchanger 51, dissipates heat to the refrigerant C2, and then flows back into the heat exchanger 51 via the heat exchange terminal 36.

<Features of the embodiment>
In the heat pump device 1 having the above-mentioned basic configuration and operation, the feature of this embodiment is the control mode of the compressor in hot charging immediately before starting the defrosting operation and when the defrosting operation is ended and the heating operation is resumed. The details thereof will be described below in order.

<Hot Charge>
That is, in this embodiment, when the heating operation is switched to the defrosting operation, the compressor 53 is stopped once, and then the four-way valve 58 is switched (from the first switching position to the second switching position). When the driving of the compressor 53 is stopped to temporarily stop the heating, the temperature of the circulating fluid L is temporarily increased before the heating is stopped, that is, a so-called hot charge is performed. Specifically, the target temperature correction unit 62Ab (corresponding to the target temperature correction means) provided in the compressor control unit 62A corrects the target temperature of the circulating fluid L to be high. As a result, the rotation speed of the compressor 53 is increased by the temperature adjustment control performed by the temperature adjustment control unit 62Aa, so that heat can be accumulated in the load pipe 31, the heat exchange terminal 36, and the refrigerant pipe 52 before the compressor 53 is stopped to start the defrosting operation. As a result, when the defrosting operation shown in FIG. 5 is performed thereafter, the temperature of the circulating fluid L during the defrosting operation can be maintained relatively high, and a decrease in comfort in the air-conditioned space can be prevented.

<Problems that may occur when heating is restarted after defrosting operation>
When the defrosting operation is completed, the compressor 53 is stopped again and then the four-way valve 58 is switched again from the second position to the first position, and similarly to the above, the discharge side of the compressor 53 is connected to the heat exchanger 51 and the suction side of the compressor 53 is connected to the air heat exchanger 55. By starting the compressor 53 after this switching, the heating operation similar to the above can be resumed (see FIG. 3).

Here, normally, the rotation speed of the compressor 53 when the defrosting operation ends and the heating operation resumes as described above is set to the same as the rotation speed immediately before the defrosting operation starts, so that the circulating liquid can be heated quickly. An example of such behavior is shown in Figure 6 as a comparative example.

6, this example shows a case where the target temperature of the circulating fluid L is 40°C and the corresponding rotation speed of the compressor 53 is 80 rps. In this example, before the defrosting operation (see time t3 to t4 described later) is performed, the target temperature of the circulating fluid L is raised (increased correction) from 40°C to 50°C by the target temperature correction unit 62Ab in order to perform the hot charge (see time t0 to time t1). Accordingly, the rotation speed of the compressor 53 increases from 80 rps to 90 rps, and the heating output by the heat pump unit 5 increases from 6 kW to 7 kW. As a result, the power consumption by the heat pump unit 5 also increases from 2 kW to 3 kW.

In this state, the compressor 53 is stopped at time t2, and the four-way valve 58 is switched (from the first switching position to the second switching position). At this time t2, the heating output of the heat pump unit 5 becomes 0 [kW], and the power consumption is also 0 [kW]. After the switching of the four-way valve 58 is completed, the compressor 53 is started at a rotation speed of 90 [rps] at time t3, and the defrosting operation is started. The defrosting operation is performed until time t4, during which the rotation speed of the compressor 53 is maintained at 90 [rps]. The power consumption is also maintained at 3 [kW]. When the defrosting operation ends at time t4, the compressor 53 is stopped again, and the four-way valve 58 is switched (from the second switching position to the first switching position). At this time t4, the power consumption of the heat pump unit 5 becomes 0 [kW] again.

On the other hand, after time t2, heating by the heat pump unit 5 is stopped, and the temperature of the circulating fluid L drops gradually until time t5. However, due to hot charging caused by the correction of the target temperature by the target temperature correction unit 62Ab, the temperature of the circulating fluid L is still maintained at a relatively high temperature of about 34°C even at time t4 when the defrosting operation ends.

After the switching of the four-way valve 58 is completed, the compressor 53 resumes the heating operation at time t5. In this comparative example, the rotation speed of the compressor 53 when the heating operation is resumed (at time t5) is controlled to 90 [rps], which is the same as the rotation speed immediately before the defrosting operation is started (at time t2). As a result of setting the rotation speed in this way, the temperature of the circulating liquid L rises sharply after time t5 when the heating operation is resumed due to the heat accumulated in the load pipe 31, the heat exchange terminal 36, and the refrigerant pipe 52. Therefore, the rotation speed of the compressor 53 is rapidly reduced from 90 [rps] after time t6 due to the temperature control of the temperature control unit 62Aa, and the heating output and power consumption also decrease sharply, but the temperature of the circulating liquid L reaches about 50 [°C] at time t7, which is significantly higher than the target temperature of 40 [°C] (overshoot).

In response to this overshoot, the rotation speed of the compressor 53 controlled by the temperature adjustment control unit 62Aa becomes 0 [rps] at the following time t8. In other words, the compressor 53 is stopped again. In this way, if the rotation speed of the compressor 53 when the heating operation is restarted is controlled to be the same as that immediately before the defrosting operation was started, a problem occurs in that the compressor 53 is stopped and the heating operation stops even though the heating operation should be continued (because the defrosting operation has ended and the heating operation has been restarted).

<Features of the embodiment>
Therefore, in this embodiment, the rotation speed of the compressor 53 when the heating operation is resumed is adjusted by a rotation speed adjustment unit 62Ac (corresponding to a rotation speed adjustment means) provided in the compressor control unit 62A to a rotation speed lower than the rotation speed of the compressor 53 immediately before the start of the defrosting operation. Details of the adjustment are shown in Fig. 7 corresponding to Fig. 6.

As shown in FIG. 7, in this embodiment, after the behavior from time t0 to time t4 similar to that in FIG. 6, the rotation speed of the compressor 53 when the heating operation is resumed (time t5) is limited to 60 [rps], which is lower than the rotation speed (90 [rps]) immediately before the defrosting operation is started (time t2). In this example, the rotation speed is even lower than the rotation speed (80 [rps]) controlled by the temperature adjustment control unit 62Aa corresponding to the target temperature (40 [°C]) of the circulating liquid L before the hot charge is performed. In other words, in this case, the adjustment by the rotation speed adjustment unit 62Ac takes precedence over the control of the rotation speed of the compressor 53 by the temperature adjustment control by the temperature adjustment control unit 62Aa.

This low adjusted rotation speed of the compressor 53 is then maintained for a predetermined period of time, in this example, until time t16. As a result, unlike the comparative example described above in which the rotation speed is the same as before the defrosting operation started, the temperature of the circulating fluid L continues to rise slowly after time t5, reaching approximately 35°C at time t16. In addition, between times t5 and t16, the heating output of the heat pump unit 5 is kept at 5 kW, and power consumption is also kept at approximately 1 kW.

After that, in this example, after time t16, the rotation speed restriction by the rotation speed adjustment unit 62Ac is released, and the rotation speed of the compressor 53 slowly increases due to the control of the temperature adjustment control unit 62Aa corresponding to the target temperature (40 [°C]) of the circulating liquid L. Correspondingly, the temperature of the circulating liquid L also slowly increases after time t16, reaches the target temperature (40 [°C]) at time t17, and thereafter stabilizes at this target temperature. Similarly, after time t16, the heating output of the heat pump unit 5 also slowly increases, reaching 6 [kW] at time t17 and stabilizing, and the power consumption also slowly increases, reaching 2 [kW] at time t17 and stabilizing. In this example, at time t18 after time t17, the rotation speed of the compressor 53 becomes 70 [rps] and stabilizes.

As described above, in this embodiment, the rotation speed of the compressor 53 when the heating operation is resumed (time t5) is adjusted to be lower than the rotation speed immediately before the defrosting operation is started (time t2), so that the heating operation can be continued without the compressor 53 being stopped as in the comparative example.

<Control procedure>
FIG. 8 shows a control procedure executed by the control device 62 to realize the above-mentioned method.

In FIG. 8, first in S2, it is determined whether or not an instruction to start heating operation has been given by the operator via the operation of a heating operation switch (not shown) provided on the remote control 60. Hereinafter, the operation of this heating operation switch will be referred to as "operation switch ON" as appropriate (as in the illustration). If the operation switch is ON, the determination is Yes, and the process proceeds to S4.

In S4, the compressor 53 is started by the compressor control unit 62A (with the four-way valve 58 in the first switching position) and heating operation is started. Then, the temperature adjustment control unit 62Aa of the compressor control unit 62A starts temperature adjustment control of the rotation speed of the compressor 53. Then, the process proceeds to S65.

In S6, it is determined whether a predetermined defrost preparation operation condition is satisfied. The defrost preparation operation condition is an index for determining whether frost has formed in the air heat exchanger 55 during heating operation and defrosting is necessary. Here, the defrost preparation operation condition is defined based on the outdoor air temperature detected by the outdoor air temperature sensor 57 and the refrigerant temperature in the air heat exchanger 55 detected by the refrigerant temperature sensor 52b. In detail, the outdoor air temperature detected by the outdoor air temperature sensor 57 is within a predetermined range (e.g., -10°C or higher and less than 2°C), and the temperature difference obtained by subtracting the refrigerant temperature in the air heat exchanger 55 from the outdoor air temperature detected by the outdoor air temperature sensor 57 is within a predetermined range (e.g., greater than 8°C). That is, when the outdoor air temperature is quite low and the temperature of the refrigerant in the air heat exchanger 55 is considerably lower than the outdoor air temperature, it is estimated that the amount of frost is so large that defrosting is necessary. Then, in S6, if the defrost preparation operation condition is satisfied, the determination is Yes, and the process proceeds to S15.

In S15, it is determined whether or not a predetermined defrost start condition is met. The control device 62 that executes S15 functions as a start determination means. In this example, the defrost start condition is the condition in S6 above, that is, the outside air temperature is within the predetermined range (e.g., -10°C or higher and less than 2°C) and the temperature difference between the outside air temperature and the refrigerant temperature in the air heat exchanger 55 is within a predetermined range (e.g., greater than 8°C) and a predetermined time (e.g., several minutes) has elapsed. If the defrost start condition is met, S15 is determined as Yes and the process proceeds to S16.

In S16, the target temperature of the circulating fluid L is corrected higher by the target temperature correction unit 62Ab. As described above, this increase in target temperature results in heat accumulation in the load pipe 31, the heat exchange terminal 36, and the refrigerant pipe 52 as a result of control by the temperature adjustment control unit 62Aa, and the hot charge is performed.

Then, in S17, it is determined whether the return temperature detected by the return liquid temperature sensor 34 at this time has reached the target temperature after correction in S16. Until the target temperature is reached, the result is No and the process waits in a loop, and once the target temperature is reached, the result is Yes and the process moves to S18.

In S18, the compressor control unit 62A stops the operation of the compressor 53. Then, in S19, the four-way valve control unit 62D switches the four-way valve 58 from the first switching position to the second switching position to perform defrosting operation. As a result, the four-way valve 58 is switched so that the inlet side of the air heat exchanger 55 is connected to the discharge side of the compressor 53, and the outlet side of the air heat exchanger 55 is connected to the inlet side of the heat exchanger 51, the outlet side of which is connected to the suction side of the compressor 53. Then, the process proceeds to S20.

In S20, the compressor 53 is started by the compressor control unit 62A, and the defrosting operation shown in FIG. 5 is started. The four-way valve control unit 62D that executes S19 and the compressor control unit 62A that executes S20 function as a defrosting start means.

Then, in S30, the compressor control unit 62A determines whether a predetermined defrosting end condition is satisfied. The compressor control unit 62A that executes S30 functions as an end determination means. The defrosting end condition is an index for determining whether the frost in the air heat exchanger 55 has sufficiently melted and the defrosting has been completed during the defrosting operation. In this case, the defrosting end condition is specified based on the refrigerant temperature in the air heat exchanger 55 detected by the refrigerant temperature sensor 52b. In detail, the condition is that the state in which the refrigerant temperature in the air heat exchanger 55 is equal to or higher than a predetermined value (e.g., 8°C) continues for a certain period of time (e.g., about 60 seconds). If this condition is satisfied, it is estimated that the frost in the air heat exchanger 55 has sufficiently melted and the defrosting has been completed. Then, if the defrosting end condition is satisfied in S30, a Yes determination is made and the process proceeds to S35.

In S35, the compressor control unit 62A stops the operation of the compressor 53. Then, in S40, the four-way valve control unit 62D switches the four-way valve 58 back to the first switching position. That is, the four-way valve 58 is switched so that the inlet side of the heat exchanger 51 is connected to the discharge side of the compressor 53, and the outlet side of the heat exchanger 51 is connected to the inlet side of the air heat exchanger 55, the outlet side of which is connected to the suction side of the compressor 53.

Then, in S50, the compressor control unit 62A starts the compressor 53, and the defrosting operation shown in FIG. 3 is started. The four-way valve control unit 62D that executes S40 and the compressor control unit 62A that executes S50 function as heating restart control means.

After that, in S60, the rotation speed adjustment unit 62Ac starts limiting (adjusting) the rotation speed of the compressor control unit 62A to a lower rotation speed than the rotation speed of the compressor 53 immediately before the start of the defrosting operation. Specifically, for example, the rotation speed is adjusted to a predetermined rotation speed that is obtained by subtracting X from the value of the rotation speed of the compressor 53 immediately before the start of the defrosting operation (all units are [rpm]). This value of X is determined according to the return temperature of the circulating liquid L detected by the return liquid temperature sensor 34 after the heating operation is resumed in S50, or the target temperature of the circulating liquid L.

An example of such a method for determining the value of X is explained with reference to FIG. 9. As shown in FIG. 9, in this example, the value of X is divided into four categories: X = 50 [°C], X = 40 [°C], X = 30 [°C], and X = 20 [°C]. These four categories are designed to provide hysteresis on the temperature rise side and the temperature fall side in order to prevent control hunting and improve control stability.

That is, when the return temperature or the target temperature (hereinafter referred to as "circulating fluid return temperature, etc." as appropriate) is rising, the range of the circulating fluid return temperature, etc. < 40 [°C] is determined to be X = 20 [°C], the range of 40 [°C] ≦ circulating fluid return temperature, etc. < 50 [°C] is determined to be X = 30 [°C], the range of 50 [°C] ≦ circulating fluid return temperature, etc. < 60 [°C] is determined to be X = 40 [°C], and the range of 60 [°C] < circulating fluid return temperature, etc. is determined to be X = 50 [°C].

On the other hand, if the circulating fluid return temperature, etc. is decreasing, the range of circulating fluid return temperature, etc. > 55 [°C] is determined to be X = 50 [°C], the range of 55 [°C] ≥ circulating fluid return temperature, etc. > 45 [°C] is determined to be X = 40 [°C], the range of 45 [°C] ≥ circulating fluid return temperature, etc. > 35 [°C] is determined to be X = 30 [°C], and the range of 35 [°C] > circulating fluid return temperature, etc. is determined to be X = 20 [°C].

However, the value of X may be set as a fixed constant.

Returning to FIG. 8, after S60, the process proceeds to S70 when a predetermined condition is satisfied, and the restriction on the rotation speed of the compressor 53 that was initiated in S60 is lifted. As a result, the rotation speed of the compressor 53 is subsequently controlled by the temperature control by the temperature adjustment control unit 62Aa. The predetermined condition may be, for example, the following two conditions (a) and (b).

(A) the return temperature of the circulating fluid L detected after the heating operation is resumed is lower than the target temperature by a predetermined value;
For example, this is the case when the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 becomes lower than the target temperature by Y [°C]. The value of Y can be a value that does not cause the overshoot, for example, 10 to 15.
Alternatively, this is the case where the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 has remained lower than the target temperature by Z [°C] or more for five minutes. The value of Z is a condition that predicts that the return temperature will not reach the target temperature, and can be, for example, 10 to 15.

(a) A temperature deviation ΔT between the return temperature of the circulating fluid L detected after the heating operation is restarted and the return temperature of the circulating fluid L detected at the time of the heating operation being restarted has reached a predetermined threshold value;
For example, this is the case where the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 after the heating operation is restarted is higher by Y' [°C] than the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 at the time of restarting the heating operation. The value of Y' can be a value that keeps the rise in the return temperature within a range where the overshoot does not occur, for example, between 5 and 10.

Once the restriction on the rotation speed of the compressor 53 is lifted in S70 as described above, the process proceeds to S80.

In S80, it is determined whether or not the operator has issued an instruction to stop the heating operation via the operation stop switch (not shown) provided on the main remote control 60a. Hereinafter, the operation of this operation stop switch will be referred to as "operation switch OFF" (as in the drawings). As long as the operation switch is not turned OFF, S80 is determined as No, and the process returns to S5 and the above-mentioned procedure is repeated. If the operation switch is turned OFF, S80 is determined as Yes and the process proceeds to S85, where the compressor control unit 62A stops driving the compressor 53, stopping the heating operation, and this flow ends.

Effects of the embodiment
As described above, in the heat pump device 1 of this embodiment, the temperature adjustment control unit 62Aa provided in the compressor control unit 62A controls the rotation speed of the compressor 53 so that the return temperature of the circulating fluid L becomes a predetermined target temperature (so-called temperature adjustment control). Then, when a defrosting operation is performed to melt the frost formed on the air heat exchanger 55 after the heating operation has continued for a certain period of time, it is first determined whether a predetermined defrosting operation start condition is satisfied (see S15). When the defrosting operation start condition is satisfied by the continuation of the heating operation, the target temperature of the circulating fluid is corrected higher by the target temperature correction unit 62Ab. As a result, the rotation speed of the compressor 53 is increased by the temperature adjustment control, so that heat can be accumulated in the circulating fluid pipe, the heat exchange terminal 36, and the refrigerant pipe 52 (so-called hot charge) before the compressor 53 is stopped to start the defrosting operation described later.

Then, the four-way valve 58 is switched to the second switching position and the compressor 53 is started, thereby starting the defrosting operation (see S19, S20), and the frost that has formed as described above can be melted by the heat released from the air heat exchanger 55. Also, at this time, as described above, hot charging is performed immediately before the compressor 53 is stopped at the start of the defrosting operation, so that the temperature of the circulating fluid L during the defrosting operation can be maintained relatively high, preventing a decrease in comfort in the heated environment.

After that, it is determined whether a predetermined defrost end condition is satisfied (see S30), and if the condition is satisfied, the defrost operation ends, the compressor 53 is stopped, and the four-way valve 58 is switched back to the first switching position (see S40, S50). In other words, by starting the compressor 53 after this switching, the heating operation can be resumed in the same manner as described above.

At this time, in this embodiment, the rotation speed adjustment unit 62Ac provided in the compressor control unit 62A adjusts the rotation speed of the compressor 53 when the heating operation is resumed to a lower rotation speed than the rotation speed of the compressor 53 immediately before the start of the defrosting operation. This makes it possible to prevent an overshoot of the circulating fluid temperature due to the accumulated heat, as in the comparative example in which the rotation speed of the compressor 53 at this time is the same as the rotation speed before the start of the defrosting operation. As a result, the heating operation can be continued without stopping the compressor 53 due to the temperature control of the temperature adjustment control unit 62Aa.

Furthermore, particularly in this embodiment, the rotation speed adjustment unit 62Ac adjusts the rotation speed of the compressor 53 when the heating operation is resumed to a predetermined rotation speed according to the return temperature of the circulating fluid L detected by the return liquid temperature sensor 34 after the heating operation is resumed, or the target temperature of the circulating fluid L.
As a result, when adjusting the rotation speed of the compressor 53 to a low value when the heating operation is resumed as described above in order to prevent the overshoot, the value of the rotation speed when the heating operation is resumed can be finely set according to the return temperature of the circulating fluid L after the heating operation is resumed or the target temperature of the circulating fluid L.

Furthermore, particularly in this embodiment, when the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 after the heating operation is resumed becomes lower than the target temperature by a predetermined value, the compressor control unit 62A controls the temperature of the compressor 53 using the temperature adjustment control unit 62Aa.
As a result, after the value of the rotation speed of the compressor 53 when the heating operation is resumed is set as described above, the set value is maintained at least until the return temperature of the circulating fluid L becomes lower than the target temperature by a predetermined value, and then the original temperature adjustment control can be restored.

Furthermore, particularly in this embodiment, when the temperature deviation between the return temperature of the circulating fluid L detected by the return liquid temperature sensor 34 and the return temperature of the circulating fluid L detected by the return liquid temperature sensor 34 at the time of resumption of the heating operation reaches a predetermined threshold value, the compressor control unit 62A controls the temperature of the rotation speed of the compressor 53 using the temperature control unit 62Aa.
As a result, after the rotation speed value of the compressor 53 when the heating operation is resumed is set as described above, the set value is maintained until the temperature deviation between the fluctuating return temperature of the circulating fluid L and the return temperature of the circulating fluid L when the heating operation is resumed reaches a predetermined threshold value, and then the original temperature adjustment control can be resumed.

In the above, so-called return temperature control is performed to control the rotation speed of the compressor 53 according to the return temperature of the circulating fluid L detected by the return fluid temperature sensor 34 on the inlet side (inlet side) of the heat exchanger 51, but this is not limited to the above. That is, a forward temperature sensor may be provided on the outlet side (outlet side) of the heat exchanger 51, and so-called forward temperature control may be performed to control the rotation speed of the compressor 53 according to the forward temperature of the circulating fluid L detected by the forward temperature sensor. In this case, the forward temperature corresponds to the actual temperature of the circulating fluid L, and the forward temperature sensor corresponds to the actual temperature detection means.

In the above, the method of solving the problem of the heating operation being stopped due to the overshoot caused by the hot charge performed before the defrosting operation is started has been described. However, the application of the present invention is not limited to the configuration of performing such hot charge. That is, for example, there is a method of providing an auxiliary heater as a circulating fluid heating auxiliary means in the load pipe 31 through which the circulating fluid L circulates, and heating the circulating fluid L to the heat exchange terminal 36 by the auxiliary heater during the defrosting operation. In this case, as in the above, (even without performing the hot charge), the temperature of the circulating fluid L during the defrosting operation can be maintained relatively high, and a decrease in comfort in the heating environment can be prevented. In this method, if the rotation speed of the compressor 53 when the heating operation is resumed is the same as the rotation speed immediately before the defrosting operation is started, there is a risk of an overshoot similar to the above due to the heat accumulated in the load pipe 31, the heat exchange terminal 36, etc. during the defrosting operation. Therefore, by applying the above method of the present invention, it is possible to obtain the effect of avoiding the stop of the compressor 53 due to the temperature control and continuing the heating operation, as in the above.

Furthermore, the present invention may be applied to a configuration in which a heat exchanger capable of receiving heat from a second heat source other than the outside air used as a heat source via the air heat exchanger 55 (in this case, this heat exchanger corresponds to the circulating fluid heating auxiliary means) is provided in the terminal circulation circuit 30, and the circulating fluid L is heated using the heat received from the second heat source in the heat exchanger. The second heat source may be, for example, a gas heater or a geothermal heat exchanger that pumps geothermal heat. In this case, as the heating of the circulating fluid L from the heat pump unit 5 is lost during the defrosting operation, the temperature of the circulating fluid L during the defrosting operation can be maintained relatively high, and a decrease in comfort in the heated environment can be prevented. However, when the defrosting operation is terminated and the heating of the circulating liquid L by the heat pump unit 5 is resumed, as described above, if the rotation speed of the compressor 53 at the time of the restart is the same as the rotation speed immediately before the defrosting operation started, the heating capacity for the circulating liquid L may become excessive in combination with the second heat source, causing an overshoot similar to that described above. Therefore, in such a case, as described above, the occurrence of an overshoot can be avoided by adjusting the rotation speed of the compressor 53 at the time of the restart of heating of the circulating liquid L by the heat pump unit 5 to be lower than the rotation speed immediately before the defrosting operation started, thereby obtaining the same effect.

In addition, the arrows in Figure 4 above show an example of signal flow and do not limit the direction of signal flow.

Furthermore, the flowchart shown in FIG. 8 does not limit the present invention to the steps shown in the above flow, and steps may be added or deleted or the order may be changed without departing from the spirit and technical concept of the invention.

In addition to the above, the methods according to the above embodiments and their variations may be used in combination as appropriate.

Although we will not provide specific examples, the present invention can be implemented with various modifications without departing from the spirit of the invention.

1 Heat pump device 5 Heat pump unit (heat pump mechanism)
30 Terminal circulation circuit 31 Load piping (circulating fluid piping)
34 Return liquid temperature sensor (actual temperature detection means)
36 Heat exchange terminal (load terminal)
50 Heat pump circuit 51 Heat exchanger (load side heat exchanger)
52 Refrigerant piping 53 Compressor 54 Expansion valve 55 Air heat exchanger (heat source side heat exchanger)
57 Outside air temperature sensor 58 Four-way valve (switching valve)
62 Control device 62A Compressor control unit (compressor control means)
62Aa Temperature control unit (temperature control means)
62Ab Target temperature correction section (target temperature correction means)
62Ac Rotation speed adjustment unit (rotation speed adjustment means)
L Circulating fluid

Claims (5)

a heat pump mechanism in which a compressor, an expansion valve, and a heat source side heat exchanger are connected by refrigerant piping;
a load-side heat exchanger that receives a refrigerant from the heat pump mechanism through the refrigerant pipe and heats the circulating liquid to a load terminal by heat exchange with the circulating liquid;
a switching valve switchable between a first switching position at which a discharge side of the compressor is connected to the load side heat exchanger serving as a condenser and a suction side of the compressor is connected to the heat source side heat exchanger serving as an evaporator, and a second switching position at which the discharge side of the compressor is connected to the heat source side heat exchanger serving as a condenser and a suction side of the compressor is connected to the load side heat exchanger serving as an evaporator;
an actual temperature detection means for detecting an actual temperature of the circulating fluid;
a compressor control means including a temperature adjustment control means for controlling a rotation speed of the compressor so that the actual temperature detected by the actual temperature detection means becomes a predetermined target temperature;
having
In a heat pump apparatus performing a heating operation in which the switching valve is switched to the first switching position and the circulating liquid to the load terminal is heated by heat received from a refrigerant in the load side heat exchanger,
a start determination means for determining whether or not a predetermined defrost start condition is satisfied during the heating operation;
a defrost start control means for switching the switching valve to the second switching position after it is determined by the start determination means that the defrost start condition is satisfied, and starting a defrosting operation of the heat source side heat exchanger by using heat received by a refrigerant in the load side heat exchanger;
an end determination means for determining whether or not a predetermined defrost end condition is satisfied after the defrost operation is started by the defrost start control means;
a heating restart control means for switching the switching valve to the first switching position and restarting the heating operation when the termination determination means determines that the defrost termination condition is satisfied;
having
The compressor control means
A rotation speed adjustment means is provided for adjusting the rotation speed Nt5 of the compressor when the heating operation is resumed by the heating restart control means to a rotation speed Nt2-X that is lower by X than the rotation speed Nt2 of the compressor immediately before the start of the defrosting operation,
The rotation speed adjusting means is
the heat pump device, wherein the X is determined in response to the actual temperature of the circulating fluid detected by the actual temperature detection means after the heating operation is resumed, or in response to the target temperature of the circulating fluid. a target temperature correction means for correcting the target temperature of the circulating fluid to be higher when the start determination means determines that the defrosting start condition is satisfied,
The defrosting start control means
2. The heat pump device according to claim 1, wherein after the actual temperature of the circulating fluid detected by the actual temperature detection means reaches the target temperature corrected higher by the target temperature correction means, the switching valve is switched to the second switching position to start the defrosting operation. 2. The heat pump device according to claim 1, wherein a circulating fluid heating auxiliary means is provided in a circulating fluid pipe through which the circulating fluid passes, and the circulating fluid is heated by the circulating fluid heating auxiliary means during the defrosting operation. The compressor control means
The rotation speed of the compressor when the heating operation is resumed is adjusted to Nt2-X based on the X determined by the rotation speed adjustment means,
2. The heat pump device according to claim 1, wherein, when the actual temperature of the circulating fluid detected by the actual temperature detection means becomes lower than the target temperature by a predetermined value after the heating operation is resumed , the rotation speed of the compressor is controlled by the temperature adjustment control means in accordance with a deviation between the actual temperature and a predetermined target temperature. a heat pump mechanism in which a compressor, an expansion valve, and a heat source side heat exchanger are connected by refrigerant piping;
a load-side heat exchanger that receives a refrigerant from the heat pump mechanism through the refrigerant pipe and heats the circulating liquid to a load terminal by heat exchange with the circulating liquid;
a switching valve switchable between a first switching position at which a discharge side of the compressor is connected to the load side heat exchanger serving as a condenser and a suction side of the compressor is connected to the heat source side heat exchanger serving as an evaporator, and a second switching position at which the discharge side of the compressor is connected to the heat source side heat exchanger serving as a condenser and a suction side of the compressor is connected to the load side heat exchanger serving as an evaporator;
an actual temperature detection means for detecting an actual temperature of the circulating fluid;
a compressor control means including a temperature adjustment control means for controlling a rotation speed of the compressor so that the actual temperature detected by the actual temperature detection means becomes a predetermined target temperature;
having
In a heat pump apparatus performing a heating operation in which the switching valve is switched to the first switching position and the circulating liquid to the load terminal is heated by heat received from a refrigerant in the load side heat exchanger,
a start determination means for determining whether or not a predetermined defrost start condition is satisfied during the heating operation;
a defrost start control means for switching the switching valve to the second switching position after it is determined by the start determination means that the defrost start condition is satisfied, and starting a defrosting operation of the heat source side heat exchanger by using heat received by a refrigerant in the load side heat exchanger;
an end determination means for determining whether or not a predetermined defrost end condition is satisfied after the defrost operation is started by the defrost start control means;
a heating restart control means for switching the switching valve to the first switching position and restarting the heating operation when the termination determination means determines that the defrost termination condition is satisfied;
having
The compressor control means
A rotation speed adjustment means for adjusting the rotation speed of the compressor when the heating operation is resumed by the heating restart control means to a rotation speed lower than the rotation speed of the compressor immediately before the start of the defrosting operation,
The rotation speed adjusting means is
adjusting a rotation speed of the compressor when the heating operation is resumed by the heating restart control means to a predetermined rotation speed according to the actual temperature of the circulating fluid detected by the actual temperature detection means after the heating operation is resumed or the target temperature of the circulating fluid;
The compressor control means
The rotation speed of the compressor when the heating operation is resumed is adjusted to the predetermined rotation speed by the rotation speed adjusting means,
and when a temperature deviation between the actual temperature of the circulating fluid detected by the actual temperature detection means and the actual temperature detected by the actual temperature detection means at the time of restarting the heating operation reaches a predetermined threshold, the rotation speed of the compressor is controlled by the temperature adjustment control means in accordance with the deviation between the actual temperature and a predetermined target temperature.

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