Heat pump water warming device

Abstract

To prevent a stop of a hot water generating operation if there is a possibility of recovering a state where a compressor does not exceed an operable pressure range even when the rotation speed is minimum.SOLUTION: A compressor control part 410B and an expansion valve control part 410C stop a boiling operation in cooperation with each other in a first state where a freezing cycle of refrigerant satisfies a predetermined cycle temperature stability condition and a state controlled to a compressor rotation speed N=Nmin continues for a first predetermined period of time, or a second state where the freezing cycle does not satisfy the predetermined cycle temperature stability condition and the state controlled to the compressor rotation speed N=Nmin continues for a short second predetermined period of time. Even when the compressor 14 shows the minimum rotation speed Nmin, the boiling operation continues while the first state or the second state is established. Thus, while there is a possibility of returning within an operable pressure range of the compressor 14, the boiling operation can be prevented from being stopped.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a heat pump water heater that generates hot water on the hot water circulation circuit side by heat exchange with a refrigerant on the heat pump device side in a water-refrigerant heat exchanger.

Background Art

[0002] Conventionally, in this type of heat pump water heater, as described in Patent Document 1, when an instruction to suppress power consumption in the heat pump device is input, the heat pump device is controlled so as to be below an upper limit value corresponding to the instruction. Also, as described in Patent Document 2, the target opening degree of the expansion valve is feedback-controlled so that the temperature difference between the discharge temperature of the refrigerant discharged from the compressor and the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger becomes a predetermined target temperature difference calculated based on the target boiling temperature, the outside air temperature, and the inlet temperature of the hot water flowing into the water-cooled refrigerant heat exchanger.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When power suppression control is performed so that the power consumption of the heat pump device is within the upper limit value as in the case described in Patent Document 1 above, specifically, for example, when the heat pump device operates receiving power supply from a household power supply of AC100V, etc. can be considered. In such a case, in order to share the limited power supply capacity between the heat pump device and ordinary household electrical appliances, the rotational speed of the compressor is restricted so that the power consumption of the heat pump device is within the power consumption upper limit value.

[0005] Here, for example, in a configuration where the opening degree of an expansion valve is feedback-controlled according to state detection values in a refrigerant circulation circuit such as a discharge temperature and an outlet temperature, as described in Patent Document 2, it is conceivable that power suppression control as described in Patent Document 1 is performed. In this case, when the upper limit value of the allowable power consumption becomes low due to the power suppression control, the rotational speed of the compressor is limited to be low, so the discharge temperature decreases, and the boiling-up temperature becomes lower than the target boiling-up temperature. As a result, the above-described target temperature difference corresponding to the target boiling-up temperature cannot be realized, and an inefficient refrigeration cycle state is reached. As a result, the power consumption increases, and in some cases, the rotational speed of the compressor further decreases to the minimum value due to the power suppression control.

[0006] Generally, in a compressor, an operable pressure range is determined in advance as an operation range in which a predetermined durability can be guaranteed. When the rotational speed of the compressor is controlled to decrease to the minimum value as described above, there is a possibility that the compressor may be operated outside the operable pressure range. Therefore, usually, there has been a problem that the operation is forcibly stopped when the rotational speed of the compressor decreases to the minimum value.

[0007] However, according to the study by the inventors of the present application, even when the rotational speed of the compressor is reduced to the minimum value as described above, it has been found that it may be possible to return to a state where the operable pressure range is not exceeded and stabilize in that state by controlling the subsequent expansion valve and controlling a circulation pump that circulates hot water in a hot and cold water circulation circuit.

Means for Solving the Problems

[0008] In order to solve the above problems, in claim 1 of the present invention, there is provided a heat pump device in which a compressor, an expansion valve, and an air heat exchanger are connected in a ring shape by a refrigerant pipe to form a refrigerant circulation circuit, a water-refrigerant heat exchanger that receives the supply of refrigerant from the heat pump device through the refrigerant pipe and generates hot water to the hot and cold water circulation circuit side by heat exchange with water, a circulation pump that circulates the hot water generated by the water-refrigerant heat exchanger, pump control means for controlling the circulation pump so that the temperature of the hot water generated by the water-refrigerant heat exchanger in the hot and cold water circulation circuit becomes a predetermined target hot water temperature, power suppression determination means for determining whether or not a power suppression signal for instructing suppression of power consumption in the heat pump device is input, a target rotation speed corresponding to the outside air temperature and the target hot water temperature, and when it is determined by the power suppression determination means that the power suppression signal is input, compressor control means for increasing or decreasing the rotation speed of the compressor within a predetermined range so as to become the target rotation speed corresponding to the upper limit value of the power consumption allowed by the power suppression signal, and expansion valve control means for increasing or decreasing the opening degree of the expansion valve so that the state detection value in the refrigerant circulation circuit becomes a desired target value. In the heat pump hot water device, the compressor control means, the expansion valve control means, and the pump control means cooperate with each other to perform a hot water generation operation for generating hot water to the hot and cold water circulation circuit. When the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit satisfies a predetermined cycle temperature stability condition and the rotation speed of the compressor is controlled to the lowest rotation speed in the predetermined range and continues for a first predetermined time in a first state, or when the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit does not satisfy the predetermined cycle temperature stability condition and the state where the rotation speed of the compressor is controlled to the lowest rotation speed continues for a second predetermined time shorter than the first predetermined time in a second state, they cooperate with each other to stop the hot water generation operation.

[0009] Further, in claim 2, in the second state, when the cycle temperature stabilization condition is not satisfied by the refrigeration cycle, and the opening degree of the expansion valve is increased by a predetermined amount by the expansion valve control means, and the state where the rotational speed of the compressor is controlled to the minimum rotational speed continues for the second predetermined time, the hot water generation operation is stopped by the cooperation of the compressor control means, the expansion valve control means, and the pump control means.

[0010] Further, in claim 3, the cycle temperature stabilization condition includes satisfying Tbo ≦ Tb + A (A: constant) where the target hot water temperature is Tbo and the hot water temperature is Tb.

[0011] Further, in claim 4, the expansion valve control means controls the opening degree of the expansion valve so that the temperature difference between the discharge temperature of the refrigerant from the compressor and the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger becomes a predetermined target temperature difference calculated based on the target hot water temperature and the inlet temperature of the hot and cold water flowing into the water-refrigerant heat exchanger.

[0012] Further, in claim 5, the cycle temperature stabilization condition includes satisfying ΔH ≦ Tout - T2 + B (B: constant) where the target temperature difference is ΔH, the discharge temperature is Tout, and the outflow temperature is T2.

[0013] Further, in claim 6, the expansion valve control means controls the opening degree of the expansion valve so that the temperature difference between the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger and the inlet temperature of the hot and cold water flowing into the water-refrigerant heat exchanger becomes constant, or so that the discharge temperature of the refrigerant from the compressor becomes the target discharge temperature.

[0014] Further, according to claim 7, it further has a hot water storage tank for storing hot and cold water, and an auxiliary heater capable of heating the hot and cold water discharged from the hot water storage tank. The hot and cold water circulation circuit is connected to the lower part of the hot water storage tank and includes an outgoing pipe for leading out the hot and cold water in the hot water storage tank, and a return pipe connected to the upper part of the hot water storage tank for returning the hot water generated by the water-refrigerant heat exchanger into the hot water storage tank.

Advantages of the Invention

[0015] According to claim 1 of the present invention, the refrigerant from the heat pump device is introduced into the water-refrigerant heat exchanger through the refrigerant pipe, and heat exchange between the refrigerant and water is performed in the water-refrigerant heat exchanger, thereby generating hot water on the hot and cold water circulation circuit side (= hot water generation operation). When such a hot water generation operation is performed, the compressor is controlled by the compressor control means so that the target rotation speed is controlled according to the outside air temperature and the target hot water temperature. In particular, when a power suppression signal is input, the target rotation speed is increased or decreased within a predetermined range so as to be a value corresponding to the upper limit value of the allowable power consumption. The expansion valve is controlled by the expansion valve control means so that the opening degree is controlled so that the state detection value in the refrigerant circulation circuit becomes a desired target value. The circulation pump is controlled by the pump control means so that the hot water temperature generated by the water-refrigerant heat exchanger becomes a predetermined target hot water temperature. As described above, when the upper limit value of the allowable power consumption is lowered by the power suppression control, the rotation speed of the compressor is limited to a low level, so the discharge temperature decreases, and the target temperature difference corresponding to the target boiling-up temperature cannot be realized, resulting in an increase in power consumption. In some cases, the rotation speed of the compressor may further decrease to the minimum value. According to claim 1, in response to the above, when the rotation speed of the compressor thus decreases to the minimum value (= the lowest rotation speed), if the refrigeration cycle of the refrigerant circulation circuit satisfies the cycle temperature stability condition (= stable state) for a first predetermined time (= the first state), or if the refrigeration cycle of the refrigerant circulation circuit does not satisfy the cycle temperature stability condition (= unstable state) for a second predetermined time shorter than the first predetermined time (the second state), the stop control of the hot water generation operation is performed. In other words, even when the compressor reaches its minimum rotational speed, as long as the first state or the second state is not established, the stop control is not performed, and the hot water generation operation continues. This makes it possible to prevent the hot water generation operation from stopping while there is a possibility of returning to a state where the operable pressure range of the compressor is not exceeded by controlling the expansion valve by the expansion valve control means and controlling the circulation pump by the pump control means.

[0016] Also, according to claim 2, when continuing the hot water generation operation without stopping in the second state, the expansion valve control means further increases the opening degree of the expansion valve by a predetermined amount. This can further enhance the possibility of returning to a state where the operable pressure range of the compressor is not exceeded.

[0017] Also, according to claim 3, a state satisfying Tbo ≦ Tb + A is set as the cycle temperature stability condition. This allows the cycle to be regarded as stable in terms of this temperature relationship when the state where the hot water temperature generated in the water-refrigerant heat exchanger is lower than the target hot water temperature but is close to it to some extent continues for a certain period.

[0018] Also, according to claim 4, in a configuration where so-called ΔH control is performed, in which the expansion valve is controlled by the expansion valve control means so that the temperature difference between the refrigerant discharge temperature and the refrigerant outflow temperature becomes the target temperature difference based on the target hot water temperature and the hot and cold water inlet temperature, in order to achieve high efficiency of the refrigeration cycle, as long as there is a possibility of achieving the target temperature difference and returning to a state where the operable pressure range is not exceeded, the hot water generation operation can be prevented from stopping.

[0019] Also, according to claim 5, a state satisfying ΔH ≦ Tout - T2 + B is set as the cycle temperature stability condition. This allows the cycle to be regarded as stable in terms of this temperature relationship when the state where the temperature difference between the refrigerant discharge temperature of the compressor and the refrigerant outflow temperature from the water-refrigerant heat exchanger is lower than the predetermined target temperature difference but is close to it to some extent continues for a certain period.

[0020] Further, according to Claim 6, in order to achieve high efficiency of the refrigeration cycle, the expansion valve is controlled by the expansion valve control means so that the temperature difference between the refrigerant outlet temperature and the hot water inlet temperature becomes constant (so-called ΔT control), or the expansion valve is controlled so that the refrigerant discharge temperature becomes the target discharge temperature (so-called discharge temperature control). In such a configuration, while there is a possibility of returning to a state where the temperature difference is constant or the target discharge temperature is achieved without deviating from the operable pressure range, the hot water generation operation can be prevented from stopping.

[0021] Further, according to Claim 7, a boiling-up operation can be performed in which the hot water generated by the heat exchange in the water-refrigerant heat exchanger is supplied into the hot water storage tank through the return pipe. Also, by making it possible to heat the hot water discharged from the hot water storage tank with an auxiliary heater, hot water heated to a temperature desired by the user can be provided.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0023] Next, an embodiment of the present invention will be described with reference to the drawings.

[0024] <Schematic circuit configuration> As shown in FIG. 1, the heat pump water heater 100 according to the present embodiment includes a tank unit 1 having a hot water storage tank 2 for storing hot water and a heat pump unit 3.

[0025] The heat pump unit 3 includes a water-refrigerant heat exchanger 15 for heating the hot water in the hot water storage tank 2 and a heating circulation pump 19 (corresponding to a circulation pump). The water-refrigerant heat exchanger 15 has a refrigerant-side flow path 15b through which refrigerant flows and a water-side flow path 15a, and exchanges heat between the high-temperature and high-pressure refrigerant and the hot water in the hot water storage tank 2. That is, the water-side flow path 15a of the water-refrigerant heat exchanger 15 and the hot water storage tank 2 are annularly connected by a heating forward pipe 5 (corresponding to a forward pipe) and a heating return pipe 6 (corresponding to a return pipe), and a heating circulation circuit 4 as a hot water circulation circuit extending between the tank unit 1 and the heat pump unit 3 is formed.

[0026] The heating forward pipe 5 is connected to the lower part of the hot water storage tank 2, and the heating return pipe 6 is connected to the upper part of the hot water storage tank 2. The heating circulation pump 19 is provided in the middle of the heating forward pipe 5, and circulates the hot water in the hot water storage tank 2 while allowing the hot water from the heating forward pipe 5 to flow through the water-side flow path 15a to the heating return pipe 6. An inlet water temperature sensor 23 for detecting the inlet water temperature T1 (the inlet temperature of the hot water) flowing from the hot water storage tank 2 into the water-side flow path 15a of the water-refrigerant heat exchanger 15 is provided in the heating forward pipe 5, and a boiling temperature sensor 24 for detecting the boiling temperature Tb flowing out from the water-side flow path 15a toward the hot water storage tank 2 is provided in the heating return pipe 6.

[0027] In the tank unit 1, a plurality of hot water storage temperature sensors 12 for detecting the temperature Tw of the hot water in the hot water storage tank 2 are provided vertically on the side surface of the hot water storage tank 2. Also, a water supply pipe 7 for supplying water to the hot water storage tank 2 is connected to the lower part of the hot water storage tank 2, and a hot water outlet pipe 8 for discharging the stored high-temperature water is also connected to the upper part of the hot water storage tank 2. The hot water outlet pipe 8 is provided with a negative pressure intake valve having a function of opening the valve to introduce air into the hot water storage tank 2 when the inside of the hot water storage tank 2 becomes negative pressure, and a pressure relief valve 119 that opens the valve to release pressure when the pressure inside the hot water storage tank 2 exceeds the opening pressure. A water supply bypass pipe 9 branches from the water supply pipe 7. The pressure relief valve 119 is provided with a manual lever (not shown) for manually opening the valve.

[0028] Furthermore, a mixing valve 10 for mixing the hot water from the hot water outlet pipe 8 and the water from the water supply bypass pipe 9 to obtain hot water at the hot water supply set temperature, a hot water supply pipe 108a for supplying the hot water mixed by the mixing valve 10 to the hot water supply terminal 125, and a hot water supply temperature sensor 11 for detecting the hot water supply temperature in the hot water supply pipe 108a are provided.

[0029] Note that a hot water supply pipe 108b is provided on the hot water supply terminal 125 side of the hot water supply pipe 108a outside the tank unit 1, and a gas heat source machine 130 (corresponding to an auxiliary heater) capable of heating the hot water mixed by the mixing valve 10 is provided between these hot water supply pipes 108a and 108b.

[0030] The heat pump unit 3 also includes a compressor 14 for compressing the refrigerant, an electronic expansion valve 16 as a decompressor for decompressing the refrigerant after passing through the water-refrigerant heat exchanger 15, an air heat exchanger 17 as a heat source side heat exchanger for performing heat exchange between the air as the heat source and the refrigerant, and an outdoor fan 67 for sending outside air into the air heat exchanger 17. The compressor 14, the refrigerant side flow path 15b of the water-refrigerant heat exchanger 15 through which the refrigerant discharged from the compressor 14 flows, the electronic expansion valve 16, and the air heat exchanger 17 are connected in a ring shape by a refrigerant pipe 18 to form a refrigerant circulation circuit 30. The electronic expansion valve 16 is driven by a pulse motor that can grasp, for example, the current position as the "pulse number position".

[0031] The refrigerant pipe 18 connects the discharge side of the compressor 14 to the inlet side of the water-refrigerant heat exchanger 15 and connects the suction side of the compressor 14 to the outlet side of the air heat exchanger. Note that the refrigerant pipe 18, the compressor 14 connected thereto, the air heat exchanger 17, and the electronic expansion valve 16 correspond to a heat pump device. In this embodiment, a dedicated power supply is not provided for the heat pump unit 3 including the compressor 14 and the like that constitute the heat pump device and the tank unit 1. The heat pump unit 3 and the tank unit 1 are both configured to operate by receiving power supply from, for example, a household power supply of AC100V or a storage battery.

[0032] In the refrigerant circulation circuit 30, for example, R32 refrigerant is used as the refrigerant to form a heat pump cycle. A discharge temperature sensor 20 for detecting the refrigerant discharge temperature Tout of the refrigerant discharged from the compressor 14 is provided at a portion on the discharge side of the compressor 14 of the refrigerant pipe 18. An outflow temperature sensor 21 for detecting the outflow temperature T2 (refrigerant outlet temperature) of the refrigerant flowing out from the refrigerant side flow path 15b and heading toward the electronic expansion valve 16 is provided in the refrigerant pipe 18 between the refrigerant side flow path 15b and the electronic expansion valve 16. An outside air temperature sensor 22 for detecting the outside air temperature Tair is provided on the air inlet side of the air heat exchanger 17.

[0033] A hot water storage control device 40 into which the detection results of the above-mentioned respective sensors 12, 11 are input is provided in the tank unit 1. Similarly, a heating control device 50 into which the detection results of the above-mentioned respective sensors 20, 22, 24, 21, 23 are input is provided in the heat pump unit 3. The heating control device 50 and the hot water storage control device 40 are communicably connected to each other, and based on the detection results of the respective sensors 12, 11, 20, 22, 24, 21, 23, etc., they cooperate with each other to control the operation of each device in the tank unit 1 and the heat pump unit 3.

[0034] Note that there is a master-slave relationship in control between the heating control device 50 and the hot water storage control device 40. For example, the hot water storage control device 40 outputs an operation command or a power suppression signal (described later) based on the detection results of the sensors 12 and 11 to the heating control device 50, and the heating control device 50 controls the operation of each device in the heat pump unit 3 based on this operation command or power suppression signal and the detection results of the sensors 20, 22, 24, 21, and 23. Hereinafter, in this specification, such a case will be described as an example.

[0035] <Heat pump input voltage and current detection device> The heat pump unit 3 is provided with a heat pump input voltage detection device 210 and a heat pump input current detection device 220 that detect the voltage value and current value input from the external power source to the heat pump unit 3 using known sensors.

[0036] <Heat pump power consumption detection device> Furthermore, the heat pump unit 3 is provided with a heat pump power consumption detection device 200 that detects the power consumed within the heat pump unit 3 (hereinafter, simply referred to as "HP power consumption" as appropriate. The same applies to the illustration). The input voltage value detected by the heat pump input voltage detection device 210 and the input voltage value detected by the heat pump input current detection device 220 are respectively output to the heat pump power consumption detection device 200. The heat pump power consumption detection device 200 calculates the HP power consumption (corresponding to the actual power consumption value in the heat pump device) by integrating the voltage value detected by the heat pump input voltage detection device 210 and the current value detected by the heat pump input current detection device 220. The calculated HP power consumption is output to the heating control device 50.

[0037] <Heating control device> Next, the heating control device 50 provided in the heat pump unit 3 will be described. Although detailed illustration is omitted, the heating control device 50 includes a storage unit that stores various data and programs, and a control unit that performs arithmetic and control processing. The functional configuration of this heating control device 50 will be described with reference to FIG. 2.

[0038] As shown in FIG. 2, the heating control device 50 functionally includes an operation switching unit 410A, a compressor control unit 410B (corresponding to compressor control means), an expansion valve control unit 410C (corresponding to expansion valve control means), an outdoor fan control unit 410D, and a pump control unit 410F (corresponding to pump control means).

[0039] The heat pump unit 3 of the present embodiment performs various controls based on an operation command output from the hot water storage control device 40. That is, an operation command output by the hot water storage control device 40 is input to the operation switching unit 410A. The operation switching unit 410A determines whether to perform a boiling-up operation (described later) in which the air heat exchanger 17 functions as an evaporator according to the operation command. Further, the operation switching unit 410A outputs operation information corresponding to the determination result to the compressor control unit 410B, the expansion valve control unit 410C, the outdoor fan control unit 410D, and the pump control unit 410F. This operation information includes the temperature Tw of the hot water in the hot water storage tank 2 detected by the hot water storage temperature sensor 12, the target boiling-up temperature Tbo (corresponding to the target warm water temperature) determined as appropriate, and the like.

[0040] In this example, the outside air temperature Tair detected by the outside air temperature sensor 22, the boiling-up temperature Tb detected by the boiling-up temperature sensor 24, the operation information corresponding to the operation command of the hot water storage control device 40, the power suppression signal from the hot water storage control device 40, and the HP power consumption from the heat pump power consumption detection device 200 are input to the compressor control unit 410B (in addition to the case of direct input, it may be input indirectly. The same applies hereinafter). The compressor control unit 410B also includes a steady state determination unit 410Ba, a maximum rotation speed setting unit 410Bb, a target rotation speed determination unit 410Bc, and a power suppression determination unit 410Bd.

[0041] The maximum rotation speed setting unit 410Bb determines the maximum value (maximum target rotation speed) of the target rotation speed of the compressor 14. The target rotation speed determination unit 410Bc sets the target rotation speed of the compressor 14 within the range (corresponding to a predetermined range) between the maximum target rotation speed set by the maximum rotation speed setting unit 410Bb and a preset minimum value Nmin, based on the input outside air temperature Tair, the target boiling temperature Tbo, and the power suppression signal, and controls the increase and decrease of the rotation speed of the compressor 14 so as to reach this target rotation speed. Note that the power suppression determination unit 410Bd and the steady state determination unit 410Ba will be described later.

[0042] In this example, the refrigerant discharge temperature Tout detected by the discharge temperature sensor 20, the refrigerant outflow temperature T2 detected by the outflow temperature sensor 21, the outside air temperature Tair detected by the outside air temperature sensor 22, the incoming water temperature T1 detected by the incoming water temperature sensor 23, the operation information corresponding to the operation command of the hot water storage control device 40, and the power suppression signal from the hot water storage control device 40 are input to the expansion valve control unit 410C. The expansion valve control unit 410C also includes a target temperature difference calculation unit 410Ca, a drive signal output unit 410Cb, a steady state determination unit 410Cc, and a power suppression determination unit 410Ce.

[0043] The target temperature difference calculation unit 410Ca calculates a target temperature difference for performing so-called target temperature difference control. That is, in the expansion valve control unit 410C of the present embodiment, so-called target temperature difference control is performed to control the opening degree of the electronic expansion valve 16 so that the temperature difference (corresponding to the state detection value in the refrigerant circulation circuit) between the refrigerant discharge temperature Tout from the compressor 14 and the refrigerant outflow temperature T2 flowing out from the water-refrigerant heat exchanger 15 becomes a predetermined target temperature difference △H (corresponding to a desired target value). Therefore, in the target temperature difference calculation unit 410Ca, the target temperature difference △H is calculated based on the target boiling temperature Tbo determined as appropriate as described above, the outside air temperature Tair, and the incoming water temperature T1 of the hot water flowing into the water-refrigerant heat exchanger 15. The drive signal output unit 410Cb generates a drive signal (control pulse) for the electronic expansion valve 16 to achieve the target temperature difference ΔH calculated by the target temperature difference calculation unit 410Ca, and outputs it to the pulse motor that drives the electronic expansion valve 16, thereby controlling the opening degree of the electronic expansion valve 16 to increase or decrease. Here, the target opening degree corresponds one-to-one to the "pulse number position" of the pulse motor that drives the electronic expansion valve 16. The control of increasing or decreasing the opening degree of the electronic expansion valve 16 is performed, for example, when the target opening degree is at the 80-pulse position and the current position of the pulse motor is at the 60-pulse position, the pulse motor is driven in the opening direction by 20 pulses. These 20 pulses become the operation amount of the electronic expansion valve 16. Note that the power suppression determination unit 410Ce and the stable state determination unit 410Cc will be described later.

[0044] The outdoor fan control unit 410D receives the outside air temperature Tair detected by the outside air temperature sensor 22 and the operation information corresponding to the operation command of the hot water storage control device 40. The outdoor fan control unit 410D sets the target rotation speed of the outdoor fan 67 based on the input operation information and the outside air temperature Tair, and controls the increase or decrease of the rotation speed of the outdoor fan 67 so that the rotation speed becomes the target rotation speed.

[0045] The pump control unit 410F receives the boiling temperature Tb detected by the boiling temperature sensor 24 and the operation information corresponding to the operation command of the hot water storage control device 40, and based on these, controls the rotation speed of the heating circulation pump 19 so that the detected boiling temperature Tb becomes the target boiling temperature Tbo.

[0046] <Boiling operation> As described above, in the heat pump unit 3 of the present embodiment, the discharge side of the compressor 14 communicates with the inlet side of the water-refrigerant heat exchanger 15, and the suction side of the compressor 14 communicates with the outlet side of the air heat exchanger. As a result, the air heat exchanger 17 functions as an evaporator that evaporates the low-temperature and low-pressure refrigerant from the electronic expansion valve 16. That is, heat is released by heat radiation from the refrigerant in the refrigerant pipe 18 in the water-refrigerant heat exchanger 15, and hot water is generated in the heating circulation circuit 4. The generated hot water is supplied into the hot water storage tank 2 through the heating return pipe 6 by the flow of the hot water in the heating circulation circuit 4 induced by the heating circulation pump 19, whereby the temperature of the hot water in the hot water storage tank 2 can be raised (= the boiling-up operation as the hot water generation operation).

[0047] <Power Suppression Control> Here, when the compressor 14 and the like of the heat pump unit 3 operate receiving power supply from a household power source or a storage battery as described above, the limited power supply capacity is shared with the tank unit 1 and each home appliance etc. in the home. Therefore, in the present embodiment, a power suppression signal instructing suppression of the power consumption in the compressor 14 and the like is input from the hot water storage control device 40 to the operation switching unit 410A, the compressor control unit 410B, and the expansion valve control unit 410C of the heating control device 50. The power suppression signal instructs the upper limit value of the power consumption allowed to be consumed in the compressor 14 and the like.

[0048] As described above, the compressor control unit 410B is provided with a power suppression determination unit 410Bd. This power suppression determination unit 410Bd determines whether or not the power suppression signal has been input. When it is determined that the power suppression signal has been input, the power suppression determination unit 410Bd outputs the value of the upper limit value of the power consumption specified by the power suppression signal to the target rotation speed determination unit 410Bc. The target rotation speed determination unit 410Bc sets the target rotation speed of the compressor 14 within the range of the maximum target rotation speed set by the maximum rotation speed setting unit 410Bb and within the range where the HP power consumption input from the heat pump power consumption detection device 200 is equal to or less than the power consumption upper limit value, and increases and decreases the rotation speed of the compressor 14 within a predetermined operable pressure range (details will be described later) so as to reach this target rotation speed.

[0049] <When the expansion valve control is performed during the power suppression control> Incidentally, when the expansion valve opening control is performed by the target temperature difference calculation unit 410Ca of the expansion valve control unit 410C such that Tout - T2 = ΔH in the state where the above-mentioned power suppression control is being performed, as shown in FIG. 3, it is conceivable that the upper limit value of the allowable power consumption becomes lower due to the power suppression control (refer to time to in FIG. 3). In such a case, since the rotation speed N of the compressor 14 is further restricted to be lower than before by the target rotation speed determination unit 410Bc of the compressor control unit 410B (refer to times t1 to t6), the discharge temperature Tout decreases, and the boiling-up temperature Tb tends to be lower than the target boiling-up temperature Tbo (refer to times t1 and t2). At this time, even if the opening degree x of the electronic expansion valve 16 is sequentially reduced by the target temperature difference calculation unit 410Ca (refer to times to to t3), the target temperature difference ΔH corresponding to the target boiling-up temperature Tbo cannot be realized, resulting in an inefficient refrigeration cycle state, and the HP power consumption may increase. In this case, in response to the above-mentioned power suppression control, the rotation speed of the compressor 14 will be further reduced to the minimum value Nmin by the target rotation speed determination unit 410Bc of the compressor control unit 410B.

[0050] <Operable pressure range> Here, generally, in the compressor 14, an operable pressure range is defined in advance as an operating range in which a predetermined durability can be guaranteed. For example, as shown in an example in FIG. 4, when the rotational speed N of the compressor 14 is taken on the horizontal axis and the discharge pressure P of the compressor 14 is taken on the vertical axis, the region on and inside the boundary line k is the operating range (= the above-mentioned operable pressure range) in which the predetermined durability of the compressor 14 is guaranteed, and the region outside the boundary line k is the operating range in which the predetermined durability is not guaranteed. As described above, when the compressor rotational speed N is controlled to decrease to the minimum value Nmin, there is a possibility that the compressor 14 will operate in the operating range outside the boundary line k where the durability is not guaranteed. Therefore, usually, when the compressor rotational speed N decreases to the minimum value Nmin, the operation of the heat pump unit 3 is controlled to be forcibly stopped.

[0051] However, according to the studies (analysis, simulation, etc.) conducted by the inventors of the present application based on a configuration equivalent to that of FIG. 1, when the compressor rotational speed N is controlled to decrease to the minimum value Nmin in this way, not only does the compressor 14 operate in the operating range outside the boundary line k where the durability is not guaranteed (see the "NG region" in FIGS. 3 and 4), but also, by subsequent control of the electronic expansion valve 16 and the heating circulation pump 19, it may be possible to return to the operable pressure range inside the boundary line k (see time t4 in FIG. 3) and stabilize at the rotational speed Ns (see FIG. 4) in that state (see time t4 to t6 in FIG. 3, see the "OK region" in FIGS. 3 and 4). This is a newly discovered fact.

[0052] Therefore, based on the above findings, in the present embodiment, a power suppression determination unit 410Bd and a stable state determination unit 410Ba are provided in the compressor control unit 410B, and a power suppression determination unit 410Ce and a stable state determination unit 410Cc are provided in the expansion valve control unit 410C.

[0053] <Method in the compressor control unit> The power suppression determination unit 410Bd of the compressor control unit 410B determines whether or not the power suppression signal is input from the hot water storage control device 40. The steady state determination unit 410Ba determines whether the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit 30 satisfies a predetermined first cycle temperature stability condition. In this example, the first cycle temperature stability condition is that Tbo ≦ Tb + A (A: a predetermined constant) ·· (Equation 1) this relationship is maintained for an appropriate period of time (e.g., 5 seconds). Note that A is, for example, 5 [°C]. The determination result by the steady state determination unit 410Ba is input to the operation switching unit 410A.

[0054] Based on the above-mentioned studies, the inventors of the present application have found that there is a possibility of shifting from the aforementioned NG region to the OK region while the state in which the rotational speed N of the compressor 14 is controlled to the minimum value Nmin by the compressor control unit 410B continues for a certain period of time in a state where the first cycle temperature stability condition is satisfied. Therefore, in the present embodiment, first, when the state in which the first cycle temperature stability condition is satisfied continues for 10 minutes (corresponding to the first predetermined time) (corresponding to an example of the first state), it is considered that there is no possibility of shifting from the NG region to the OK region, and control to stop the boiling operation is performed (refer to the flow of FIG. 5 described later). The inventors of the present application have also found that there is still a possibility of shifting from the aforementioned NG region to the OK region even in a state where the first cycle temperature stability condition is not satisfied. However, in that case, it has also been found that the determination of the duration during which the compressor rotational speed N is the minimum value Nmin should be shorter than the above-mentioned first predetermined time. Therefore, in the present embodiment, further, when the state in which the first cycle temperature stability condition is not satisfied continues for 3 minutes (corresponding to the second predetermined time) (corresponding to an example of the second state), it is considered that there is no possibility of shifting from the NG region to the OK region, and control to stop the boiling operation is performed (refer to the flow of FIG. 5 described later).

[0055] <Method in the expansion valve control unit> The power suppression determination unit 410Ce of the expansion valve control unit 410C determines whether the power suppression signal has been input from the hot water storage control device 40. The steady state determination unit 410Cc determines whether the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit 30 satisfies a predetermined second cycle temperature stability condition. In this example, the second cycle temperature stability condition is that △H≦Tout-T2+B (B: a predetermined constant) ··(Equation 2) the relationship is maintained for an appropriate time (for example, 5 seconds). Note that B is, for example, 5 [°C]. The determination result by the steady state determination unit 410Cc is input to the operation switching unit 410A.

[0056] Based on the above-mentioned studies, the inventors of the present application have found that there is a possibility that the rotation speed N of the compressor 14 can be shifted from the above-mentioned NG region to the OK region while the state in which the rotation speed N of the compressor 14 is controlled to the minimum value Nmin by the compressor control unit 410B continues for a certain period of time in a state where the second cycle temperature stability condition is satisfied. Therefore, in the present embodiment, first, when the state in which the second cycle temperature stability condition is satisfied continues for 10 minutes (corresponding to the first predetermined time) (corresponding to another example of the first state), it is considered that there is no possibility of shifting from the NG region to the OK region, and control to stop the boiling operation is performed (see the flow of FIG. 5 described later). The inventors of the present application have also found that there is still a possibility of shifting from the above-mentioned NG region to the OK region even in a state where the second cycle temperature stability condition is not satisfied. However, in that case, it has also been found that the determination of the duration during which the compressor rotation speed N is the minimum value Nmin should be shorter than the first predetermined time. Therefore, in the present embodiment, further, when the state in which the second cycle temperature stability condition is not satisfied continues for 3 minutes (corresponding to the second predetermined time) (corresponding to another example of the second state), it is considered that there is no possibility of shifting from the NG region to the OK region, and control to stop the boiling operation is performed (see the flow of FIG. 5 described later).

[0057] <Control Procedure> To realize the above method, the control procedure executed by the heating control device 50 of the present embodiment will be described with reference to the flowchart of FIG. 5.

[0058] In FIG. 5, first at S10, based on the operation information from the operation switching unit 410A corresponding to the operation command from the hot water storage control device 40, the boiling-up operation is started.

[0059] Thereafter, at S15, the target opening degree of the electronic expansion valve 16 is determined by the target temperature difference calculation unit 410Ca and the drive signal output unit 410Cb of the expansion valve control unit 410C such that Tout - T2 becomes the predetermined target temperature difference ΔH (so-called target temperature difference control). A drive instruction signal is output from the drive signal output unit 410Cb to the aforementioned pulse motor so as to achieve the target opening degree determined by this target temperature difference control.

[0060] Then, at S20, it is determined by the power suppression determination units 410Bd and 410Ce of the compressor control unit 410B and the expansion valve control unit 410C whether the aforementioned power suppression signal has been input.

[0061] If the power suppression signal has not been input, S20 is determined as No, and the process proceeds to S55 described later. If the power suppression signal has been input, S20 is determined as Yes, and the process proceeds to S25. At S25, the power suppression determination unit 410Bd of the compressor control unit 410B determines whether the value of the HP power consumption from the heat pump power consumption detection device 200 is greater than the power consumption upper limit value allowed by the power suppression signal. If HP power consumption ≤ power consumption upper limit value, S25 is determined as No, and the process proceeds to S55 described later. If HP power consumption > power consumption upper limit value, S25 is determined as Yes, and the process proceeds to S30.

[0062] At S30, the maximum target rotation speed of the compressor 14 is changed (reduced) to a value such that the HP power consumption becomes equal to or less than the power consumption upper limit value by the maximum rotation speed setting unit 410Bb of the compressor control unit 410B.

[0063] Thereafter, in S35, it is determined by the maximum rotation speed setting unit 410Bb of the compressor control unit 410B whether or not the rotation speed N of the compressor 14 has reached the aforementioned minimum value Nmin. At this time, the actual rotation speed N of the compressor 14 detected by a known method is used for the determination. If N > Nmin, S35 is determined as No and the process proceeds to S55.

[0064] In S55, the operation switching unit 410A determines whether or not it is the timing to end the boiling operation, such as when the temperature Tw in the hot water storage tank 2 reaches a predetermined value. If it is the timing to end, it is determined as Yes and the process proceeds to S60 described later. If it is not yet the timing to end the boiling operation in S55, it is determined as No and the process returns to S10, and the boiling operation (accompanied by the target temperature difference control in S15) continues.

[0065] On the other hand, if N = Nmin in S35, it is determined as Yes and the process proceeds to S40. In S40, the stability state determination units 410Ba and 410Cc of the compressor control unit 410B and the expansion valve control unit 410C determine whether or not the aforementioned first cycle temperature stability condition (refer to the aforementioned formula 1) or the second cycle stability condition (refer to the aforementioned formula 2) regarding the refrigeration cycle is satisfied.

[0066] If the first cycle temperature condition or the second cycle temperature condition is satisfied, S40 is determined as Yes and the process proceeds to S42. In S42, it is determined whether or not the state where N = Nmin, S35 is determined as Yes, and the refrigeration cycle is stable and S40 is determined as Yes continues for a first predetermined time (10 minutes in the aforementioned example). If it does not continue for the first predetermined time, it is determined as No and the process returns to S35 and the same procedure is repeated. If it continues for the first predetermined time, it is determined as Yes and the process proceeds to S60 described later.

[0067] On the other hand, if neither the first cycle temperature condition nor the second cycle temperature condition is satisfied in S40, S40 determines No and proceeds to S52. In S52, it is determined whether or not the state where S35 determines Yes with N = Nmin and the refrigeration cycle is still unstable and S40 determines No continues for a second predetermined time (3 minutes in the above example). If it does not continue for the second predetermined time, it is determined No, returns to S35, and the same procedure is repeated. If it continues for the second predetermined time, it is determined Yes and proceeds to S60 described below.

[0068] In S60, based on the operation information (indicating the stop of the boiling operation) from the operation switching unit 410A, the compressor 14 is stopped by the compressor control unit 410B, the boiling operation ends, and this flow ends.

[0069] <Effects of the Embodiment> As described above, in the present embodiment, the refrigerant from the refrigerant circulation circuit 30 is introduced into the water-refrigerant heat exchanger 15 via the refrigerant pipe 18, and heat exchange between the refrigerant and water is performed in the water-refrigerant heat exchanger 15, thereby supplying warm water to the heating circulation circuit 4 side (= boiling operation). When such a boiling operation is performed, the compressor 14 has its target rotational speed controlled by the compressor control unit 410B according to the outside air temperature Tair and the target boiling temperature Tbo. In particular, when a power suppression signal is input, the target rotational speed is increased or decreased within a predetermined range so as to be a value corresponding to the allowable upper limit value of power consumption. The electronic expansion valve 16 has its opening degree x controlled by the expansion valve control unit 410C so that the state detection value (Tout - T2 in the above example) in the refrigerant circulation circuit 30 becomes a desired target value (ΔH in the above example). The heating circulation pump 19 is controlled by the pump control unit 410F so that the boiling temperature Tb of the warm water generated in the water-refrigerant heat exchanger 15 becomes a predetermined target boiling temperature Tbo.

[0070] As described above, when the upper limit value of the power consumption allowed by the power suppression control becomes low, the rotational speed N of the compressor is limited to a low value, so the discharge temperature Tout decreases, and the target temperature difference ΔH corresponding to the target boiling temperature Tbo cannot be achieved, the power consumption increases, and the rotational speed N of the compressor may further decrease to the minimum value Nmin. According to the present embodiment, in response to the above, when the rotational speed N of the compressor thus decreases to the minimum value Nmin (= the lowest rotational speed), if the refrigeration cycle of the refrigerant circulation circuit 30 continues in a state (= stable state) satisfying the cycle temperature stability condition for a first predetermined time (= first state), or if the refrigeration cycle of the refrigerant circulation circuit 30 continues in a state (= unstable state) not satisfying the cycle temperature stability condition for a second predetermined time shorter than the first predetermined time (second state), the stop control of the boiling operation is performed (see S60 in FIG. 5).

[0071] In other words, even when the compressor 14 reaches the lowest rotational speed Nmin, while the first state or the second state is not established (S42, S52: No), the stop control is not performed, and the boiling operation continues. Thereby, while there is a possibility of returning within the operable pressure range of the compressor 14 by the control of the electronic expansion valve 16 by the expansion valve control unit 410C and the control of the heating circulation pump 19 by the pump control unit 410F, it is possible not to stop the boiling operation.

[0072] Further, in particular, in the present embodiment, a state satisfying Tbo ≤ Tb + A is set as the cycle temperature stability condition (first cycle temperature stability condition). Thereby, when the boiling temperature Tb generated in the water-refrigerant heat exchanger 15 is lower than the target boiling temperature Tbo but remains at a value close to it for a certain period, it can be regarded that the cycle is stable in this temperature relationship.

[0073] Further, in particular in this embodiment, in order to achieve high efficiency of the refrigeration cycle, the electronic expansion valve 16 is controlled by the expansion valve control unit 410C so that the temperature difference Tout - T2 between the refrigerant discharge temperature Tout and the refrigerant outlet temperature T2 becomes the target temperature difference ΔH based on the target boiling temperature Tbo and the hot water inlet temperature T1. That is, so-called target temperature difference control is performed (see S15). And in the configuration where such target temperature difference control is performed, while there is a possibility of achieving the target temperature difference ΔH and returning within the operable pressure range, the boiling operation can be prevented from stopping.

[0074] Further, in particular in this embodiment, a state satisfying ΔH ≦ Tout - T2 + B is defined as the cycle temperature stabilization condition (second cycle temperature stabilization condition). Thereby, when the temperature difference Tout - T2 between the refrigerant discharge temperature Tout of the compressor 14 and the refrigerant outlet temperature T2 from the water-refrigerant heat exchanger 15 is lower than the predetermined target temperature difference ΔH but is close to it to some extent and continues for a certain period, the cycle can be regarded as being stable in this temperature relationship.

[0075] Further, in particular in this embodiment, the heating circulation circuit 4 includes a heating supply pipe 5 that leads out the hot water in the hot water storage tank 2, and a heating return pipe 6 that returns the hot water generated in the water-refrigerant heat exchanger 15 to the hot water storage tank 2. Thereby, the boiling operation can be performed by supplying the hot water generated by the heat exchange in the water-refrigerant heat exchanger 15 into the hot water storage tank 2 via the heating return pipe 6. Also, by making it possible to heat the hot water discharged from the hot water storage tank 2 with the gas heat source machine 130, hot water heated to the temperature desired by the user can be provided.

[0076] Note that the present invention is not limited to the above aspects and is applicable without changing its gist. Hereinafter, such modified examples will be described.

[0077] (1) When correcting the expansion valve opening degree in the opening direction The functional configuration of the heating control device in this modified example is shown in FIG. 6. In the heating control device 50 shown in FIG. 6, a target opening degree correction unit 410Cd is provided in the expansion valve control unit 410C. The target opening correction unit 410Cd adds a correction amount in the opening direction to the target opening determined by the drive signal output unit 410Cb according to the determination result of the steady state determination unit 410Cc. The drive signal output unit 410Cb controls the increase and decrease of the opening of the electronic expansion valve 16 so that it becomes the target opening after correction by the target opening correction unit 410Cd.

[0078] In this modification, the control procedure executed by the heating control device 50 is shown in the flowchart of FIG. 7 corresponding to FIG. 5. In the flowchart shown in FIG. 7, S45 and S50 are added between S40 and S52. When neither the first cycle temperature condition nor the second cycle temperature condition is satisfied in S40 and S40 is determined to be No, the process proceeds to newly provided S45.

[0079] In S45, the target opening correction unit 410Cd determines the correction amount in the opening direction to be added to the target opening of the electronic expansion valve 16 determined by the drive signal output unit 410Cb based on the target temperature difference control started in S15. After that, in S50, in the drive signal output unit 410Cb, the correction amount (fixed value, for example, 10 pulses) determined in S45 is added to the target opening of the electronic expansion valve 16 determined based on the target temperature difference control from S15, and this is output as the operation amount to the pulse motor of the electronic expansion valve 16. Then, the process proceeds to S52. Note that the processing of S45 and S50 is performed only once.

[0080] That is, in this modification, when the refrigeration cycle does not satisfy the cycle temperature stability condition (S40: N0), and accordingly, in S45 and S50, the expansion valve opening x is corrected by a predetermined amount by the expansion valve control unit 410C and the compressor rotational speed N is controlled to the minimum value Nmin, and this state continues for the second predetermined time, S52 is determined to be Yes and the boiling-up operation is stopped. The processing other than the above is the same as that in FIG. 5, and the description is omitted.

[0081] In this modification, when the refrigeration cycle continues the boiling-up operation without stopping under a condition where the cycle temperature stability condition is not satisfied, the expansion valve control unit 410C further corrects the expansion valve opening degree x by a predetermined amount. Thereby, the possibility of returning the compressor 14 to within the operable pressure range can be further increased.

[0082] (2) Others In the above, the case where the expansion valve control unit 410C performs the target temperature difference control for determining the target opening degree of the electronic expansion valve 16 such that the temperature difference between the refrigerant discharge temperature Tout and the refrigerant outflow temperature T2 becomes ΔH based on the target boiling-up temperature Tbo, the outside air temperature Tair, and the inlet water temperature T1 has been described as an example, but it is not limited thereto. That is, discharge temperature control may be performed to control the valve opening degree of the electronic expansion valve 16 so that the refrigerant discharge temperature Tout matches a predetermined target discharge temperature. Alternatively, discharge pressure control may be performed to control the valve opening degree of the electronic expansion valve 16 so that the discharge pressure of the refrigerant discharged from the compressor 14 becomes a desired value. Alternatively, other control may be performed to control the opening degree of the electronic expansion valve 16 so that an appropriate state detection value in the heat pump cycle of the heat pump unit 3 becomes a desired target value. Also in these cases, the same effects can be obtained by the same method as described above.

[0083] Further, in the above embodiment, the hot water generated as described above in the water-refrigerant heat exchanger 15 is supplied to the hot water storage tank 2 by connecting the hot water storage tank 2 via the heating circulation circuit 4 including the heating supply pipe 5 and the heating return pipe 6 on the load side of the water-refrigerant heat exchanger 15, and the boiling-up operation is performed. However, it is not limited thereto. That is, an appropriate heat exchange terminal such as a fan coil, a floor heating panel, or a panel convector may be connected via a circulation circuit that circulates hot water similar to the heating circulation circuit 4, and heating operation as hot water generation operation may be performed by supplying hot water to the heat exchange terminal. In this case, for example, the target return temperature corresponding to the set temperature level of the remote control for operating the heat exchange terminal corresponds to the target hot water temperature described above. Also in this case, the same effects can be obtained by the same method as described above.

[0084] Also, as the heat pump cycle in the above embodiment, an ejector cycle using an ejector as a decompressor may be used.

[0085] Also, in the above embodiment, as the heat source machine, taking the case of an air source heat pump in which an outdoor fan 67 that blows outside air while passing refrigerant through an air heat exchanger 17 as a heat source side heat exchanger is used, and the outside air as a heat source and the refrigerant are heat-exchanged, has been described as an example, but it is not limited thereto. That is, the heat source machine may be configured such that water or antifreeze is supplied to the heat source side heat exchanger and heat exchange between these liquids and the refrigerant takes place in the heat source side heat exchanger. Also, a heat source side heat exchanger may be provided in the ground or in a relatively large-capacity water source, and the ground or the water source and the refrigerant may be heat-exchanged in this heat source side heat exchanger. Furthermore, a composite heat source type configuration including a heat pump circuit using the heat of the ground or the water source and another heat pump circuit using air heat may be used. Furthermore, as long as it can heat-exchange with the refrigerant in the heat source side heat exchanger, instead of the liquid, the outside air, or the water source, other things (for example, gases including smoke, exhaust gas, various high-temperature gases, etc., and flowing solids including hot sand, dust, various particles, etc.) may be passed through the heat source side heat exchanger, or heat from sunlight, reflected light, other radiation, etc. may be supplied to and used by the heat source side heat exchanger.

Explanation of Signs

[0086] 1 Tank unit 2 Hot water storage tank 3 Heat pump unit 4 Heating circulation circuit (hot water circulation circuit) 5 Heating forward pipe (forward pipe) 6 Heating return pipe (return pipe) 14 Compressor 15 Water-refrigerant heat exchanger 16 Electronic expansion valve (expansion valve) 17 Air heat exchanger 18 Refrigerant pipe 19 Heating circulation pump (circulation pump) 20 Discharge Temperature Sensor 21 Outlet Temperature Sensor 22 Ambient Temperature Sensor 23 Inlet Water Temperature Sensor 30 Refrigerant Circulation Circuit 40 Hot Water Storage Control Device 50 Heating Control Device 100 Heat Pump Water Heater 130 Gas Heat Source Machine (Auxiliary Heater) 410A Operation Switching Unit 410B Compressor Control Unit (Compressor Control Means) 410Bd Power Suppression Judgment Unit (Power Suppression Judgment Means) 410C Expansion Valve Control Unit (Pressure Reducing Device Control Means) 410Cb Drive Signal Output Unit 410Cd Target Opening Degree Correction Unit 410Ce Power Suppression Judgment Unit (Power Suppression Judgment Means) 410F Pump Control Unit (Pump Control Means) Tair Ambient Temperature Tb Boiling Temperature (Hot Water Temperature) Tbo Target Boiling Temperature (Target Hot Water Temperature) Tout Refrigerant Discharge Temperature T1 Inlet Water Temperature T2 Outlet Temperature

Claims

1. A heat pump device in which a compressor, an expansion valve, and an air heat exchanger are annularly connected by refrigerant pipes to form a refrigerant circulation circuit, a water-refrigerant heat exchanger that receives the supply of refrigerant from the heat pump device via the refrigerant pipes and generates hot water for the hot and cold water circulation circuit side by heat exchange with water, a circulation pump for circulating the hot water generated by the water-refrigerant heat exchanger, pump control means for controlling the circulation pump so that the temperature of the hot water generated by the water-refrigerant heat exchanger in the hot and cold water circulation circuit becomes a predetermined target hot water temperature, power suppression determination means for determining whether a power suppression signal for instructing suppression of power consumption in the heat pump device is input, a target rotation speed corresponding to the outside air temperature and the target hot water temperature, and when it is determined by the power suppression determination means that the power suppression signal is input, the rotation speed of the compressor is increased or decreased within a predetermined range so as to be the target rotation speed corresponding to the upper limit value of the allowable power consumption permitted by the power suppression signal, compressor control means, expansion valve control means for increasing or decreasing the opening degree of the expansion valve so that the state detection value in the refrigerant circulation circuit becomes a desired target value, having, In the heat pump water heater, the compressor control means, the expansion valve control means, and the pump control means cooperate with each other to perform a hot water generation operation for generating hot water for the hot and cold water circulation circuit. In a first state where the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit satisfies a predetermined cycle temperature stability condition and the rotation speed of the compressor is controlled to the lowest rotation speed in the predetermined range for a first predetermined time, or, In a second state where the refrigeration cycle of the refrigerant flowing through the refrigerant circulation circuit does not satisfy the predetermined cycle temperature stability condition and the state where the rotation speed of the compressor is controlled to the lowest rotation speed continues for a second predetermined time shorter than the first predetermined time, stopping the hot water generation operation A heat pump water heater characterized by the above.

2. In the second state, when the state where the rotation speed of the compressor is controlled to the lowest rotation speed continues for the second predetermined time with the opening degree of the expansion valve increased by a predetermined amount by the expansion valve control means in response to the refrigeration cycle not satisfying the cycle temperature stability condition, the hot water generation operation is stopped by the cooperation of the compressor control means, the expansion valve control means, and the pump control means.

2. The heat pump hot water system according to claim 1.

3. The cycle temperature stability condition is When the target hot water temperature is Tbo and the hot water temperature is Tb, Tbo≦Tb+A (A: constant) This includes satisfying 3. The heat pump hot water system according to claim 1 or 2.

4. The expansion valve control means A heat pump hot water device as described in claim 1 or claim 2, characterized in that the opening degree of the expansion valve is controlled so that the temperature difference between the discharge temperature of the refrigerant from the compressor and the outlet temperature of the refrigerant flowing out of the water-refrigerant heat exchanger becomes a predetermined target temperature difference calculated based on the target hot water temperature and the inlet water temperature of the hot water flowing into the water-refrigerant heat exchanger.

5. The cycle temperature stability condition is When the target temperature difference is ΔH, the discharge temperature is Tout, and the outflow temperature is T2, △H≦Tout−T2+B (B: constant) This includes satisfying 5. The heat pump hot water system according to claim 4.

6. The expansion valve control means The temperature difference between the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger and the inflow temperature of the hot and cold water flowing into the water-refrigerant heat exchanger is constant. Or, The discharge temperature of the refrigerant from the compressor is set to a target discharge temperature.

3. The heat pump hot water system according to claim 1, wherein an opening degree of the expansion valve is controlled.

7. A hot water storage tank for storing hot water; An auxiliary heater capable of heating hot water discharged from the hot water storage tank; and The hot water circulation circuit includes: A supply pipe connected to a lower portion of the hot water storage tank and for discharging hot water from the hot water storage tank; A return pipe connected to an upper portion of the hot water storage tank and returning the hot water generated in the water-refrigerant heat exchanger into the hot water storage tank; Includes 2. The heat pump hot water system according to claim 1.

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