Heat pump hot water system

Abstract

To prevent undershoot of a hot water temperature in switching from normal output operation to high output operation under execution of power suppression control.SOLUTION: In a heat pump water heater 100, a target opening of an electronic expansion valve 16 is determined by a target opening determination portion 410Cc of an expansion valve control portion 410C so that a temperature difference between a refrigerant discharge temperature Tout and a refrigerant outflow temperature T2 is a prescribed target temperature difference ▵H. Upon switching from operation in a rated mode to operation in a high-performance mode, a correction amount in an opening direction is added to the target opening determined as mentioned above by the target opening determination portion 410Cc, by a target opening correction portion 410Cb. In a case when a power suppression signal is input from outside to execute power suppression control, the correction amount in the opening direction determined by the target opening correction portion 410Cb is reduced by the correction amount adjustment portion 410Cd in comparison with a case when the power suppression signal is not input. As a result, inconvenience such as occurrence of undershoot can be prevented.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This invention relates to a heat pump water heater that generates hot water by heat exchange with a refrigerant in a water-refrigerant heat exchanger.

Background Art

[0002] [[ID=ll]] Conventionally, in this type of heat pump water heater, as described in Patent Document 1, the target opening degree of a pressure reducer is feedback-controlled so that the temperature difference between the discharge temperature of the refrigerant discharged from a compressor and the outflow temperature of the refrigerant flowing out from a water-refrigerant heat exchanger becomes a predetermined target temperature difference calculated based on a target boiling temperature, an outside air temperature, and the inlet temperature of the hot and cold water flowing into the water-refrigerant heat exchanger.

[0003] Also, as described in Patent Document 2, there is a device that switches between operation in a normal mode for obtaining a predetermined normal heating capacity when the load is small and operation in a high-output mode for obtaining a heating capacity greater than that in the normal mode when the load is large.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When performing feedback control of the pressure reducer according to Patent Document 1, when switching from normal output operation to high-output operation as in the technique of Patent Document 2, in order to prevent an excessive increase (so-called overshoot) in the refrigerant pressure and hot water temperature due to an increase in the compressor rotation speed, a correction amount in the opening direction may be added to the target opening degree of the pressure reducer by the feedback control. In this specification, the target opening of the pressure reducer (for example, expressed as an opening of XX [%]) may be expressed as the pulse position of the driving means that drives the pressure reducer to that target opening, such as a pulse motor. In this case, since the target opening and the pulse position correspond one-to-one, when the pressure reducer is driven in the opening or closing direction, the difference between these two pulse positions, that is, the difference between the current pulse position and the pulse position after driving (target position), becomes the "operated variable". On the other hand, the "correction amount" refers to the deviation of the target opening degree before and after correction in the opening degree control of the pressure reducer, that is, the difference in opening degree between the target opening degree before correction and the target opening degree after correction (the same applies hereinafter).

[0006] On the other hand, in recent years, a configuration has been proposed in which the heat pump device operates by receiving power from, for example, a household AC100V power supply or a storage battery, without providing a dedicated AC200V power supply. In this case, since the limited power capacity is shared between the heat pump device and various electrical appliances in a typical household, a power suppression signal instructing the heat pump device to suppress power consumption may be input from an external source. The power suppression signal indicates the upper limit of power consumption that the heat pump device is allowed to consume. When the power suppression signal is input, power suppression control is performed so that the power consumed by the heat pump device is within the upper limit of power consumption, and the rotation speed of the compressor is limited.

[0007] When switching from normal output operation to high output operation occurs while this power suppression control is in place, the control system applies a correction amount to the opening direction of the pressure reducer while the compressor rotation speed is limited. This causes the compressor discharge temperature to drop too low, resulting in a decrease in the hot water temperature (a so-called undershoot).

[0008] Furthermore, the same problems arise not only when feedback control of the pressure reducer is performed as described above, but also when so-called discharge temperature control is performed, which controls the opening degree of the pressure reducer so that the discharge temperature from the compressor reaches the target discharge temperature. In other words, as the compressor speed increases when transitioning from normal mode to high-power mode, the discharge temperature tends to rise. Therefore, in discharge temperature control, as described above, a correction amount is sometimes added to the target opening of the pressure reducer in order to prevent overshoot of the hot water temperature. Therefore, as described above, when switching to high-output operation occurs during power suppression control, the control that applies the correction amount in the opening direction is performed while the compressor rotation speed is limited, which can cause the compressor discharge temperature to drop too low and result in undershoot. [Means for solving the problem]

[0009] To solve the above problems, claim 1 of the present invention provides a heat pump hot water device comprising: a heat pump device in which a compressor, a pressure reducer, and an air heat exchanger are connected by refrigerant piping; and a water-refrigerant heat exchanger that receives refrigerant supplied from the heat pump device via the refrigerant piping and generates hot water for the hot water circulation circuit side by heat exchange with water, wherein the heat pump hot water device is capable of selectively performing operation in a normal mode in which hot water is generated for the hot water circulation circuit side with a predetermined normal output, and operation in a high output mode in which hot water is generated for the hot water circulation circuit side with an output greater than the normal output, wherein the heat pump hot water device comprises: a compressor control means that controls the rotation speed of the compressor to increase or decrease to a target compressor rotation speed corresponding to each mode, depending on whether it is operating in the normal mode or the high output mode; and a pressure reducer control means that controls the opening degree of the pressure reducer, wherein the pressure reducer control means controls the discharge temperature of the refrigerant discharged from the compressor or a value corresponding to the discharge temperature to control the opening degree of the hot water generated. The system includes: a target opening determination means for determining a target opening of the pressure reducer that is a target value calculated based on the standard water temperature; an operation switching determination means for determining whether or not a switch has been made from operation in the normal mode to operation in the high-power mode; a target opening correction means for adding a correction amount in the opening direction to the target opening determined by the target opening determination means when the operation switching determination means determines that a switch has been made to operation in the high-power mode; a power suppression determination means for determining whether or not a power suppression signal instructing the suppression of power consumption in the heat pump device has been input; and a correction amount adjustment means for adjusting the correction amount in the opening direction by the target opening correction means when the power suppression determination means determines that the power suppression signal has been input to be smaller than the correction amount in the opening direction when the power suppression determination means does not determine that the power suppression signal has been input.

[0010] Furthermore, in claim 2, the correction amount adjustment means adjusts the correction amount variably according to the upper limit of power consumption that is permitted by the power suppression signal when the power suppression determination means determines that the power suppression signal has been input.

[0011] Furthermore, in claim 3, if the power suppression determination means determines that the power suppression signal has been input, the correction amount is further adjusted variably according to the ambient temperature.

[0012] Furthermore, in claim 4, the correction amount adjustment means, when the power suppression determination means determines that the power suppression signal has been input, reduces the correction amount to a smaller value when the power consumption upper limit is small than when it is large, and reduces the correction amount to a smaller value when the outside air temperature is low than when it is high.

[0013] Furthermore, in claim 5, the target opening correction means adds a correction amount in the opening direction to the target opening determined by the target opening determination means, after the operation switching determination means has determined that a switch to operation in high output mode has been made, for a predetermined number of limited times. [Effects of the Invention]

[0014] According to claim 1 of this invention, the target opening degree determination means determines the target opening degree of the pressure reducer by the pressure reducer control means such that the discharge temperature of the refrigerant from the compressor or a value corresponding to the discharge temperature becomes a target value calculated based on the target hot water temperature of the generated hot water, thereby maximizing the efficiency of the heat pump device.

[0015] If the operation switching determination means determines that the operation has been switched from normal mode to high-output mode, the target opening correction means applies a correction amount in the opening direction to the target opening determined by the target opening determination means. This prevents an excessive rise in refrigerant pressure or hot water temperature (so-called overshoot) due to an increase in compressor rotation speed.

[0016] On the other hand, if the power suppression determination means determines that a power suppression signal has been input from an external source for the purpose of executing power suppression control, the correction amount adjustment means adjusts the correction amount in the opening direction determined by the target opening correction means to be smaller than the correction amount in the opening direction when it is not determined that a power suppression signal has been input. In other words, the correction amount in the opening direction of the pressure reducer is kept low in response to the limited rotational speed of the compressor. As a result, problems such as the occurrence of undershoot can be avoided.

[0017] Furthermore, the method of increasing or decreasing the correction amount in correcting the target opening of the pressure reducer has the following significance. In this case, the target rotational speed of the compressor is maintained at a relatively high speed, the same as before the switch from normal mode to high output mode and before the power suppression signal was input. Therefore, the compressor can operate at the highest possible rotational speed while satisfying the power consumption limit imposed by power suppression control, thus reliably avoiding undershoot depending on the environmental conditions and operating state at the time.

[0018] Furthermore, according to claim 2, the amount of correction in the opening direction (the difference in opening degree before and after correction) when the pulse motor operates the opening degree of the pressure reducer is variably adjusted according to the upper limit of power consumption allowed by the power suppression signal. By performing such variable adjustment of the correction amount, for example, when the upper limit of power consumption is 800[W], the correction amount expressed in terms of pulse position of the pulse motor is reduced by 5[pulses] to the negative side compared to when there is no power limit, resulting in the correction amount in the opening direction being 15[pulses]. When it is 600[W], the correction amount is reduced by 10[pulses] to the negative side, resulting in the correction amount in the opening direction being 10[pulses]. When it is 400[W], the correction amount is reduced by 15[pulses] to the negative side, resulting in the correction amount in the opening direction being 5[pulses]. In this way, a suitable opening degree control mode can be set according to the upper limit value that limits the rotational speed of the compressor.

[0019] Also, generally, the lower the temperature of the pressure reducer, the greater the influence on the refrigerant temperature even with a small amount of opening operation. According to claim 3, in response to this, the correction amount adjustment means variably adjusts the value of the correction amount according to the outside air temperature. Thereby, for example, when the upper limit value of power consumption is 800 [W], on the relatively low temperature side, the correction amount is adjusted by reducing it by 5 [pulses] on the negative side, so that the correction amount in the opening direction is 15 [pulses], and on the high temperature side, the correction amount is adjusted by reducing it by 0 [pulses] on the negative side, so that the correction amount in the opening direction is 20 [pulses], and so on. In this way, it is possible to achieve a preferable opening degree control mode in which the correction amount in the opening direction on the low temperature side is suppressed according to the outside air temperature.

[0020] Also, according to claim 4, for example, when the upper limit value of power consumption is 800 [W], on the low temperature side, the correction amount is adjusted by reducing it by 5 [pulses] on the negative side, so that the correction amount in the opening direction is 15 [pulses], and on the high temperature side, the correction amount is adjusted by reducing it by 0 [pulses] on the negative side, so that the correction amount in the opening direction is 20 [pulses]. Also, when it is 600 [W], on the low temperature side, the correction amount is adjusted by reducing it by 10 [pulses] on the negative side, so that the correction amount in the opening direction is 10 [pulses], and on the high temperature side, the correction amount is adjusted by reducing it by 5 [pulses] on the negative side, so that the correction amount in the opening direction is 15 [pulses]. When it is 400 [W], on the low temperature side, the correction amount is adjusted by reducing it by 15 [pulses] on the negative side, so that the correction amount in the opening direction is 5 [pulses], and on the high temperature side, the correction amount is adjusted by reducing it by 10 [pulses] on the negative side, so that the correction amount in the opening direction is 10 [pulses], and so on. In this way, it is possible to achieve a preferable opening degree control mode according to the outside air temperature. [[ID=�]]

[0021] Also, according to claim 5, instead of permanently correcting the target opening degree by the target opening degree correction means, by setting a limit to a predetermined number of times, while avoiding the complication of the control logic from the conventional control content and aiming for simplification, it is possible to avoid the inconvenience of the occurrence of undershoot.

Brief Description of the Drawings

[0022] [Figure 1]Schematic configuration diagram of a heat pump water heater according to an embodiment of the present invention [Figure 2] Functional block diagram showing the functional configuration of the heating control device [Figure 3] Explanatory diagram showing the behavior of the upper limit value of power consumption, outside air temperature, and correction amount of the target opening degree of the electronic expansion valve during power suppression control [Figure 4] Flowchart showing the control procedure executed by the heating control device [Figure 5] Explanatory diagrams respectively showing the behavior of the operation mode switching state, boiling-up temperature, opening degree of the electronic expansion valve, rotational speed of the compressor, and refrigerant discharge pressure when the correction amount adjustment is performed

Mode for Carrying Out the Invention

[0023] Next, an embodiment of the present invention will be described based on 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-cooled medium heat exchanger 15 (corresponding to a water-refrigerant heat exchanger) and a heating circulation pump 19 (corresponding to a circulation pump) for heating the hot water in the hot water storage tank 2. The water-cooled medium 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-cooled medium 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 over the tank unit 1 and the heat pump unit 3 is formed.

[0026] The heating supply 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 installed in the middle of the heating supply pipe 5 and circulates the hot water in the hot water storage tank 2 while allowing the hot water from the heating supply pipe 5 to flow to the heating return pipe 6 via the water-side flow path 15a. The heating supply pipe 5 is equipped with an inlet water temperature sensor 23 that detects the inlet water temperature T1 (hot water inlet temperature) flowing into the water-side flow path 15a of the water-refrigerant heat exchanger 15, and the heating return pipe 6 is equipped with a boiling temperature sensor 24 that detects the boiling temperature Tb flowing out from the water-side flow path 15a toward the hot water storage tank 2.

[0027] In the tank unit 1, multiple hot water temperature sensors 12 for detecting the temperature Tw of the hot water inside the hot water storage tank 2 are provided on the side of the hot water storage tank 2, extending both vertically and horizontally. A water supply pipe 7 is connected to the lower part of the hot water storage tank 2 to supply water to the hot water storage tank 2, and a hot water outlet pipe 8 is connected to the upper part of the hot water storage tank 2 to discharge the hot water stored therein. The hot water outlet pipe 8 is equipped with a negative pressure intake valve 119 that opens when the inside of the hot water storage tank 2 becomes negative pressure to introduce air into the hot water storage tank 2, and a water supply bypass pipe 9 is branched off from the water supply pipe 7. Furthermore, the system includes a mixing valve 10 that mixes hot water from the outlet pipe 8 with cold water from the water supply bypass pipe 9 to produce hot water at the 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 temperature sensor 11 for detecting the hot water temperature in the hot water supply pipe 108a.

[0028] Furthermore, 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 unit 130 capable of heating the hot water mixed by the mixing valve 10 is provided between these hot water supply pipes 108a and 108b.

[0029] The heat pump unit 3 also includes a compressor 14 for compressing the refrigerant, an electronic expansion valve 16 as a pressure reducer for reducing the pressure of the refrigerant after it has passed through the water-refrigerant heat exchanger 15, an air heat exchanger 17 as a heat source-side heat exchanger for heat exchange between air as a heat source and the refrigerant, and an outdoor fan 67 for supplying outside air to 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 refrigerant piping 18 to form a refrigerant circulation circuit 30. The electronic expansion valve 16 is driven, for example, by a pulse motor capable of determining its current position as a "pulse count position".

[0030] The refrigerant piping 18 connects the discharge side of the compressor 14 to the inlet side of the water refrigerant heat exchanger 15, and the suction side of the compressor 14 to the outlet side of the air heat exchanger. The refrigerant piping 18 and the compressor 14, air heat exchanger 17, and electronic expansion valve 16 connected thereto constitute a heat pump device. In this embodiment, the heat pump unit 3 and tank unit 1, which include the compressor 14 and other components that constitute the heat pump device, do not have dedicated power supplies. Both the heat pump unit 3 and the tank unit are configured to operate by receiving power from, for example, a household AC 100V power supply or a storage battery.

[0031] In the refrigerant circulation circuit 30, for example, R32 refrigerant is used as the refrigerant, and a heat pump cycle is formed. A discharge temperature sensor 20 is provided at the discharge side of the compressor 14 of the refrigerant piping 18 to detect the refrigerant discharge temperature Tout of the refrigerant discharged from the compressor 14. An outlet temperature sensor 21 is provided in the refrigerant piping 18 between the refrigerant-side flow path 15b and the electronic expansion valve 16 to detect the outlet temperature T2 (refrigerant outlet temperature) of the refrigerant flowing out from the refrigerant-side flow path 15b toward the electronic expansion valve 16. An outside air temperature sensor 22 (corresponding to an outside air temperature detection means) is provided at the air inlet side of the air heat exchanger 17 to detect the outside air temperature Tair.

[0032] The tank unit 1 is equipped with a hot water storage control device 40 to which the detection results of the aforementioned sensors 12 and 11 are input. Similarly, the heat pump unit 3 is equipped with a heating control device 50 to which the detection results of the aforementioned sensors 20, 22, 24, 21, and 23 are input. The heating control device 50 and the hot water storage control device 40 are connected to each other so as to be able to communicate with each other, and they cooperate with each other to control the operation of the respective devices in the tank unit 1 and the heat pump unit 3 based on the detection results of the aforementioned sensors 12, 11, 20, 22, 24, 21, and 23.

[0033] Furthermore, there may be a master-slave control relationship between the heating control device 50 and the hot water storage control device 40. For example, the hot water storage control device 40 may output operation commands and power suppression signals (described later) based on the detection results of sensors 12 and 11 to the heating control device 50, and the heating control device 50 may control the operation of each device in the heat pump unit 3 based on these operation commands and power suppression signals and the detection results of sensors 20, 22, 24, 21, and 23. In the following description, this case will be used as an example.

[0034] <Heat pump power consumption detection device> The heat pump unit 3 is equipped with a heat pump power consumption detection device 200 that detects the power consumed within the heat pump unit 3 (hereinafter referred to as "HP power consumption" as appropriate; the same applies to the figures). The heat pump power consumption detection device 200 detects the voltage and current values ​​supplied to the heat pump unit 3 using known sensors, and calculates the HP power consumption by integrating these voltage and current values. The calculated HP power consumption is output to the heating control device 50.

[0035] <Heating control device> Next, the heating control device 50 provided in the heat pump unit 3 will be described. Although detailed illustrations are omitted, the heating control device 50 includes a storage unit for storing various data and programs, and a control unit for performing calculation and control processing. The functional configuration of this heating control device 50 will be explained with reference to Figure 2.

[0036] As shown in Figure 2, the heating control device 50 functionally includes an operation switching unit 410A, a compressor control unit 410B (corresponding to a compressor control means), an expansion valve control unit 410C (corresponding to a pressure reducer control means), an outdoor fan control unit 410D, and a pump control unit 410F.

[0037] In this embodiment, the heat pump unit 3 is equipped with two selectable modes: a rated mode (equivalent to the normal mode) that generates hot water to the hot water storage tank 2 with a predetermined rated output (for example, around 2.5 kW, equivalent to the normal output), and a high-performance mode (equivalent to the high-output mode) that generates hot water with a higher output than the rated output (for example, around 4.0 kW, equivalent to a higher output than the normal output). Which of these modes the heat pump unit 3 is operated in is determined based on the operation command output from the hot water storage control device 40.

[0038] In other words, the operation switching unit 410A receives an operation command output by the hot water storage control device 40. The operation switching unit 410A determines, in response to the operation command, which of the two modes the heat pump unit 3 will actually operate in, and whether or not to perform the boiling operation in which the air heat exchanger 17 functions as an evaporator. The operation switching unit 410A also outputs operation information corresponding to the decision 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, and the target boiling temperature Tbo, which is determined as appropriate.

[0039] In this example, the compressor control unit 410B receives the following inputs: the outside air temperature Tair detected by the outside air temperature sensor 22, the boiling temperature Tb detected by the boiling 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 (these may be input directly or indirectly; the same applies hereinafter). The compressor control unit 410B also includes an operation mode determination unit 410Ba, a maximum rotation speed setting unit 410Bb, a target rotation speed determination unit 410Bc, and a power suppression determination unit 410Bd.

[0040] The operating mode determination unit 410Ba determines, based on the operating information from the operating mode switching unit 410A, which of the aforementioned rated mode and high-performance mode the unit is operating in. The maximum rotational speed setting unit 410Bb determines the maximum value of the target rotational speed (maximum target rotational speed) for the corresponding compressor 14 based on the determination result from the operating mode determination unit 410Ba. For example, in rated mode, the maximum target rotational speed is set to 50 [rps], and in high-performance mode, the maximum target rotational speed is set to 90 [rps]. The target rotation speed determination unit 410Bc sets a target rotation speed for the compressor 14 within the set maximum target rotation speed range, based on the input ambient temperature Tair, boiling temperature Tb, and power suppression signal, and controls the rotation speed of the compressor 14 to increase or decrease to achieve this target rotation speed. The power suppression determination unit 410Bd will be described later.

[0041] In this example, the expansion valve control unit 410C receives the following inputs: the refrigerant discharge temperature Tout detected by the discharge temperature sensor 20, the refrigerant discharge temperature T2 detected by the discharge temperature sensor 21, the ambient temperature Tair detected by the ambient temperature sensor 22, the inlet water temperature T1 detected by the inlet 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. The expansion valve control unit 410C also includes an operation switching determination unit 410Ca, a target opening degree correction unit 410Cb, a target opening degree determination unit 410Cc, a correction amount adjustment unit 410Cd, and a power suppression determination unit 410Ce.

[0042] The target opening degree determination unit 410Cc determines the target opening degree of the electronic expansion valve 16 such that the temperature difference Tout-T2 (corresponding to a value corresponding to the discharge temperature) between the refrigerant discharge temperature Tout and the refrigerant outflow temperature T2 becomes a predetermined target temperature difference △H (corresponding to a target value) calculated based on the target boiling temperature Tbo (corresponding to the target hot water temperature), the ambient temperature Tair, and the inlet water temperature T1. Here, the target opening degree corresponds one-to-one with the "pulse count position" of the pulse motor that drives the electronic expansion valve 16.

[0043] The operation switching determination unit 410Ca determines, based on the operation information from the operation switching unit 410A, whether or not a switch has been made from operation in the rated mode to operation in the high-performance mode. When the operation switching determination unit 410Ca determines that the operation has been switched to the high-performance mode, the target opening degree correction unit 410Cb adds a correction amount in the opening direction to the target opening degree determined by the target opening degree determination unit 410Cc. The correction amount adjustment unit 410Cd and the power suppression determination unit 410Ce will be described later.

[0044] The outdoor fan control unit 410D receives the outdoor air temperature Tair detected by the outdoor air temperature sensor 22 and the operation information corresponding to the operation command of the hot water storage control device 40. Based on the input operation information and the outdoor air temperature Tair, the outdoor fan control unit 410D sets a target rotational speed for the outdoor fan 67 and controls the rotational speed of the outdoor fan 67 to increase or decrease so that it reaches the target rotational 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 controls the rotation speed of the heating circulation pump 19 based on these.

[0046] <Boiling operation> As described above, in the heat pump unit 3 of this embodiment, the discharge side of the compressor 14 is connected to the inlet side of the water-refrigerant heat exchanger 15, and the suction side of the compressor 14 is connected to the outlet side of the air heat exchanger, thereby causing the air heat exchanger 17 to function as an evaporator that evaporates the low-temperature, low-pressure refrigerant from the electronic expansion valve 16. That is, heat is released in the water-refrigerant heat exchanger 15 by heat dissipation from the refrigerant in the refrigerant piping 18, and hot water is generated in the heating circulation circuit 4. The generated hot water is supplied to the hot water storage tank 2 via the heating return pipe 6 by the flow of hot water in the heating circulation circuit 4 induced by the heating circulation pump 19, thereby raising the temperature of the hot water in the hot water storage tank 2 (= boiling operation as a hot water generation operation).

[0047] <Power Suppression Control> Here, as described above, when the compressor 14 of the heat pump unit 3 operates by receiving power from a household power supply or storage battery, the limited power capacity is shared with the tank unit 1 and various household electrical appliances. Therefore, in this embodiment, a power suppression signal instructing the suppression of power consumption in the compressor 14 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 indicates the upper limit of power consumption that the compressor 14 is allowed to consume.

[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. If it is determined that the power suppression signal has been input, the power suppression determination unit 410Bd outputs the value of the power consumption upper limit specified by the power suppression signal to the target rotational 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 in which the HP power consumption input from the heat pump power consumption detection device 200 is less than or equal to the power consumption upper limit, and controls the rotation speed of the compressor 14 to increase or decrease to achieve this target rotation speed.

[0049] <When a power reduction control system is activated and a change in operation occurs> By the way, when the above-mentioned power suppression control is being performed and the system switches from operation in the rated mode to operation in the high-performance mode, the rotational speed of the compressor 14 is limited by the target rotational speed determination unit 410Bc of the compressor control unit 410B as described above. In this state, the target opening degree correction unit 410Cb of the expansion valve control unit 410C applies a correction amount to the opening direction of the electronic expansion valve 16 as described above. As a result, the refrigerant discharge temperature Tout from the compressor 14 may drop too low, causing the temperature of the hot water in the heating circulation circuit 4 to decrease (a so-called undershoot occurs).

[0050] Therefore, in this embodiment, the expansion valve control unit 410C is provided with a correction amount adjustment unit 410Cd and a power suppression determination unit 410Ce. The power reduction determination unit 410Ce determines whether or not the power reduction signal has been input from the hot water storage control device 40. When the power suppression determination unit 410Ce determines that the power suppression signal has been input, the correction amount adjustment unit 410Cd adjusts the amount of correction for the opening of the electronic expansion valve 16 in the opening direction by the target opening degree correction unit 410Cb to be smaller than the amount of correction for the opening direction when it is not determined that the power suppression signal has been input. In detail, when the correction amount adjustment unit 410Cd determines that the power suppression signal has been input, it variably adjusts the correction amount in the opening direction of the opening of the electronic expansion valve 16 according to the power consumption upper limit value specified by the power suppression signal. In particular, in this example, the correction amount adjustment unit 410Cd variably adjusts the correction amount according to both the power consumption upper limit value and the outside air temperature Tair. If the target opening degree correction unit 410Cb has made a correction, the expansion valve control unit 410C controls the opening of the electronic expansion valve 16 to achieve the corrected target opening degree. If the target opening degree correction unit 410Cb has not made a correction, the expansion valve control unit 410C controls the opening of the electronic expansion valve 16 to achieve the target opening degree determined by the target opening degree determination unit 410Cc. Here, the control of increasing or decreasing the opening of the electronic expansion valve 16 is performed such that, for example, if 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 20 pulses in the opening direction. These 20 pulses constitute the aforementioned manipulated amount.

[0051] An example of the variable adjustment of the correction amount is shown in Figure 3. Figure 3 shows the adjustment behavior of the correction amount in the opening direction of the opening degree of the electronic expansion valve 16, with the outside air temperature Tair on the horizontal axis, as indicated by the number of pulses of the drive instruction signal to the pulse motor that drives the electronic expansion valve 16 (the larger the number of pulses, the more the opening degree of the electronic expansion valve 16 is driven in the opening direction).

[0052] As shown in Figure 3, in this example, if no power suppression signal is input and there is no upper limit on power consumption, the opening correction amount for the electronic expansion valve 16 in the opening direction is set to 20 [pulses], regardless of the value of the outside air temperature Tair. When the power consumption limit is 800[W], the correction amount is adjusted to 15[pulses] if the ambient temperature Tair is less than -5[°C], and the correction amount is adjusted to 20[pulses] if the ambient temperature Tair is -5[°C] or higher. When the power consumption limit is 600[W], the correction amount is adjusted to 10[pulses] if the ambient temperature Tair is less than 0[°C], and the correction amount is adjusted to 15[pulses] if the ambient temperature Tair is 0[°C] or higher. When the power consumption limit is 400[W], the correction amount is adjusted to 5[pulses] if the ambient temperature Tair is less than 5[°C], and the correction amount is adjusted to 10[pulses] if the ambient temperature Tair is 5[°C] or higher.

[0053] As described above, in this example, when the upper limit of power consumption is small, the correction amount becomes smaller than when it is large, and when the outside air temperature Tair is low, the correction amount becomes smaller than when it is high.

[0054] <Control Procedure> A control procedure performed by the heating control device 50 of this embodiment, including the adjustment of the opening correction amount of the electronic expansion valve shown as an example in Figure 3, will be explained with reference to the flowchart in Figure 4.

[0055] In Figure 4, first, at S10, the boiling operation is started based on the operation information from the operation switching unit 410A corresponding to the operation command from the hot water storage control device 40.

[0056] Subsequently, in S15, the target opening degree determination unit 410Cc of the expansion valve control unit 410C determines the target opening degree of the electronic expansion valve 16 such that Tout-T2 becomes the predetermined target temperature difference ΔH (so-called ΔH control). To achieve the target opening degree determined by this ΔH control, a drive instruction signal is output from the target opening degree correction unit 410Cb to the pulse motor at a predetermined period t (see Figure 5 described later).

[0057] Then, in S20, the power suppression determination unit 410Ce of the expansion valve control unit 410C determines whether or not the power suppression signal has been input.

[0058] If no power suppression signal is input, S20 is determined to be No, and the process proceeds to S25. In S25, the correction amount adjustment unit 410Cd uniformly sets the amount of correction in the opening direction of the opening of the electronic expansion valve 16, which is executed by the target opening correction unit 410Cb when the operation is switched from the rated mode to the high-performance mode (in other words, when the operation switching determination unit 410Ca determines that the operation has been switched to the high-performance mode), to a predetermined fixed value (20 [pulses] in the example of Figure 3). If a power suppression signal is input, S20 is determined to be Yes, and the process proceeds to S30. In S30, the correction amount adjustment unit 410Cd variably calculates the amount of correction in the opening direction of the opening of the electronic expansion valve 16, which is executed by the target opening correction unit 410Cb when the operation is switched to the high-performance mode, as shown in an example in Figure 3. After S25 and S30, the program will transition to S35.

[0059] In S35, the operation switching determination unit 410Ca of the expansion valve control unit 410C determines whether or not the system has switched from the rated mode to the high-performance mode. If the system has not switched, the determination is No, and the process returns to S10 and the same procedure is repeated. If the system switches from rated mode to high-performance mode, a "Yes" determination is made (the operating mode determination unit 410Ba of the compressor control unit 410B also determines that it has entered high-performance mode), and the system proceeds to S40.

[0060] In S40, the maximum rotational speed setting unit 410Bb of the compressor control unit 410B changes the maximum target rotational speed of the compressor 14 from that for rated mode to that for high-performance mode. Following the example above, the maximum target rotational speed is changed from 50 [rps] to 90 [rps], and the rotational speed of the compressor 14 is increased so as not to exceed the HP power consumption limit.

[0061] Then, in S45, the target opening degree determination unit 410Cc of the expansion valve control unit 410Cc determines the target opening degree of the electronic expansion valve 16, which is first executed as △H control after the mode switching detected in S35 (hereinafter, as appropriate, this will be simply referred to as "initial control," "first," etc., and the same applies to the figures).

[0062] Subsequently, in S50, the target opening correction unit 410Cb adds to the target opening of the electronic expansion valve 16, which was calculated in S30 or determined in S25, the amount of correction in the opening direction of the opening of the electronic expansion valve 16 that was determined in S45. In other words, in this example, after switching from the rated mode to the high-performance mode, a correction amount in the opening direction of the electronic expansion valve 16 is applied to the target opening determined by the target opening determination unit 410Cc for a predetermined number of times (1 time in this example) in order to perform ΔH control, and in the next control cycle, only normal ΔH control is performed.

[0063] In S55, the operation switching unit 410A determines whether it is time to terminate the boiling operation, such as when the temperature Tw in the hot water storage tank 2 has reached a predetermined value. If it is time to terminate, a Yes determination is made, and the boiling operation is terminated based on the operation information from the operation switching unit 410A, ending this flow. If it is not yet time to terminate the boiling operation in S55, a No determination is made, and the process returns to S10, where the boiling operation (with △H control in S15) continues.

[0064] <Effects of the Embodiment> As described above, in the heat pump hot water system 100 of this embodiment, the target opening degree of the electronic expansion valve 16 is determined by the target opening degree determination unit 410Cc of the expansion valve control unit 410C so that the value corresponding to the discharge temperature Tout of the refrigerant from the compressor 14 becomes a target value calculated based on the target hot water temperature. Specifically, in this example, the ΔH control performed by the target opening degree determination unit 410Cc determines the target opening degree of the electronic expansion valve 16 so that the temperature difference Tout-T2 between the discharge temperature Tout of the refrigerant from the compressor 14 and the outflow temperature T2 of the refrigerant from the water refrigerant heat exchanger 15 becomes a predetermined target temperature difference ΔH. This maximizes the efficiency of the heat pump system, which includes the compressor 14, the electronic expansion valve 16, and the air heat exchanger 17.

[0065] If the operation switching determination unit 410Ca determines that the system has switched from rated mode to high-performance mode, the target opening correction unit 410Cb adds a correction amount in the opening direction to the target opening determined by the target opening determination unit 410Cc as described above. This prevents an excessive rise in refrigerant pressure and hot water temperature (so-called overshoot) due to an increase in the compressor 14 rotational speed.

[0066] On the other hand, if the power suppression determination unit 410Ce determines that a power suppression signal has been input from outside the heating control device 50 in order to execute power suppression control, the correction amount adjustment unit 410Cd adjusts the correction amount in the opening direction determined by the target opening degree correction unit 410Cb as described above to be smaller than the correction amount in the opening direction when it is not determined that a power suppression signal has been input.

[0067] Figures 5(a) to (e) show examples of the behavior of each part due to the above adjustments. Figure 5(a) shows the switching state of the operating mode, Figure 5(b) shows the behavior of the boiling temperature Tb, Figure 5(c) shows the behavior of the opening degree of the electronic expansion valve 16, Figure 5(d) shows the behavior of the rotational speed of the compressor 14, and Figure 5(e) shows the behavior of the refrigerant discharge pressure. In this example, the case where the upper limit of power consumption due to the input power suppression signal is 400 [W] is shown as an example. In Figures 5(b) to (e), the case where the correction amount of the opening degree of the electronic expansion valve 16 is not adjusted according to this embodiment is shown by a dashed line as a comparative example.

[0068] As shown in Figure 5(a), when the operation switches from rated mode to high-performance mode at time t0, the rotational speed of the compressor 14 does not increase easily due to the power consumption limit imposed by the power suppression signal (see times t0 to t5), as shown in Figure 5(d). In this state, if the control that adds a correction amount to the opening direction for the ΔH control of the electronic expansion valve 16 is simply performed (without adjustment by the correction amount adjustment unit 410Cd), the refrigerant discharge pressure from the compressor 14 (see Figure 5(e)) and the refrigerant discharge temperature Tout may drop too low, and a phenomenon in which the boiling temperature Tb decreases (so-called undershoot; see times t0 to t2), as shown in Figure 5(b), may occur.

[0069] Therefore, in this embodiment, as shown in Figure 5(c), the initial correction amount for the opening direction of the electronic expansion valve 16 is adjusted to the negative direction (compared to the comparative example shown by the dashed line) by the method described above, and the value of the correction amount becomes smaller (see times t0 to t1). As a result, the decrease in refrigerant discharge pressure and refrigerant discharge temperature Tout from the compressor 14 can be suppressed (see times t0 to t2 in Figure 5(e)), and the decrease in boiling temperature Tb can be prevented (see times t0 to t2 in Figure 5(b)), thus avoiding the occurrence of the aforementioned undershoot.

[0070] In this embodiment, instead of directly controlling the target rotational speed of the compressor 14 in response to the power suppression signal, the method of increasing or decreasing the correction amount in the correction of the target opening of the electronic expansion valve 16 has the following significance. That is, by using this method, the target rotational speed of the compressor 14 is maintained at a relatively high target rotational speed (90 [rps] in the above example), the same as before the switch from rated mode to high-performance mode and before the power suppression signal was input. Therefore, the compressor 14 can operate at the highest possible rotational speed while satisfying the power consumption limit imposed by power suppression control, thus reliably avoiding undershoot depending on the environmental conditions and operating state at the time.

[0071] Furthermore, in this embodiment, as described above using Figure 3, the value of the correction amount is variably adjusted according to the upper limit of power consumption allowed by the power suppression signal. For example, in the above example, when the upper limit of power consumption is 800[W], the correction amount, expressed in terms of pulse position of the pulse motor, is adjusted to a negative value of 5[pulses] compared to when there is no power limit, so that the correction amount in the opening direction of the electronic expansion valve 16 is 15[pulses]. Similarly, in the case of 600[W], the correction amount is adjusted to a negative value of 10[pulses] so that the correction amount in the opening direction is 10[pulses], and in the case of 400[W], the correction amount is adjusted to a negative value of 15[pulses] so that the correction amount in the opening direction is 5[pulses], and so on. In this way, a suitable opening degree control mode can be set according to the value of the upper limit of power consumption that limits the rotational speed of the compressor 14.

[0072] Furthermore, generally speaking, the electronic expansion valve 16 has a greater impact on the refrigerant temperature even with a small amount of opening operation at lower temperatures. This embodiment specifically addresses this, and as described above using Figure 3, the correction amount adjustment unit 410Cd variably adjusts the value of the correction amount according to the ambient temperature Tair. As a result, as shown in Figure 3, for example, when the power consumption upper limit is 800 [W], the correction amount is adjusted to decrease by 5 [pulses] on the lower temperature side to set the correction amount in the opening direction to 15 [pulses], and on the higher temperature side, the correction amount is adjusted to decrease by 0 [pulses] on the lower temperature side to set the correction amount in the opening direction to 20 [pulses], and so on. In this way, a suitable opening degree control can be achieved, in which the correction amount in the opening direction on the lower temperature side is kept relatively low according to the ambient temperature Tair.

[0073] Furthermore, in this embodiment, as described above with reference to Figure 3, when the upper limit of power consumption is small, the value of the correction amount is made smaller than when it is large, and when the outside air temperature Tair is low, the value of the correction amount is made smaller than when it is high. As shown in Figure 3, for example, when the power consumption limit is 800[W], the correction amount for the opening direction is set to 15[pulses] on the low-temperature side by reducing the correction amount by 5[pulses] to the negative side, and to 20[pulses] on the high-temperature side by reducing the correction amount by 0[pulses] to the negative side. When the power consumption limit is 600[W], the correction amount for the opening direction is set to 10[pulses] on the low-temperature side by reducing the correction amount by 10[pulses] to the negative side, and to 15[pulses] on the high-temperature side by reducing the correction amount by 5[pulses] to the negative side. When the power consumption limit is 400[W], the correction amount for the opening direction is set to 5[pulses] on the low-temperature side by reducing the correction amount by 15[pulses] to the negative side, and to 10[pulses] on the high-temperature side by reducing the correction amount by 10[pulses] to the negative side, and so on. In this way, a suitable opening degree control mode can be set according to the outside air temperature Tair.

[0074] Furthermore, in this embodiment in particular, after switching to the high-performance mode, the target opening correction unit 410Cb applies a correction amount in the opening direction to the target opening determined by the target opening determination unit 410Cc for a predetermined number of times (in the above example, only for the first time). By limiting the correction of the target opening by the target opening correction unit 410Cb to a predetermined number of times rather than performing it permanently, it is possible to simplify the control logic by avoiding the complexity of conventional control content while avoiding the inconvenience of undershoot occurring.

[0075] Furthermore, the present invention is not limited to the embodiments described above, and is applicable without changing its spirit.

[0076] In other words, in the above embodiment, the example given was a case in which the target opening degree determination unit 410Cc of the expansion valve control unit 410Cc determines the target opening degree of the electronic expansion valve 16 by performing ΔH control, such that the temperature difference between the refrigerant discharge temperature Tout and the refrigerant outflow temperature T2 is ΔH based on the target boiling temperature Tbo, the ambient temperature Tair, and the inlet water temperature T1. However, the invention is not limited to this. That is, the expansion valve control unit 410C may also perform feedback control of the opening degree of the electronic expansion valve 16 (so-called discharge temperature control) so that the refrigerant discharge temperature Tout becomes the target boiling temperature Tbo plus a constant value [°C]. In this case as well, if the control is simply performed by adding a correction amount in the opening direction to the discharge temperature control while there is a limit on the power consumption upper limit, the same undershoot as described above may occur. Therefore, by reducing the value of the correction amount in the opening direction of the electronic expansion valve 16 using the same method as described above, the occurrence of the undershoot can be avoided.

[0077] Furthermore, in the above embodiment, the hot water storage tank 2 is connected to the load side of the water-refrigerant heat exchanger 15 via a heating circulation circuit 4 consisting of a heating supply pipe 5 and a heating return pipe 6, thereby performing the boiling operation in which the hot water generated in the water-refrigerant heat exchanger 15 is supplied to the hot water storage tank 2. However, the system is not limited to this. That is, a heating operation as a hot water generation operation may be performed by connecting an appropriate heat exchange terminal such as a fan coil, floor heating panel, or panel convector via a circulation circuit that circulates hot water similar to the heating circulation circuit 4, and supplying hot water to the heat exchange terminal to perform heating. In this case, for example, the target return temperature corresponding to the set temperature level of the remote control that operates the heat exchange terminal corresponds to the target hot water temperature. In this case as well, the same effect can be obtained using the same method as described above.

[0078] Furthermore, the heat pump cycle in the above embodiment may also be an ejector cycle using an ejector as a pressure reducer.

[0079] Furthermore, in the above embodiment, the heat source unit was described as an air-source type heat pump that has an outdoor fan 67 that blows outside air while passing a refrigerant through an air heat exchanger 17 which serves as a heat source side heat exchanger, and heat is exchanged between the outside air as a heat source and the refrigerant, but it is not limited to this. That is, the heat source unit may be configured such that water or antifreeze is supplied to the heat source side heat exchanger, and heat is exchanged between these liquids and the refrigerant in the heat source side heat exchanger. Alternatively, a heat source-side heat exchanger may be installed underground or in a relatively large-capacity water source, and this heat source-side heat exchanger may be configured to exchange heat between the ground or water source and the refrigerant. Furthermore, a combined heat source type configuration may be provided, comprising a heat pump circuit using the heat from the ground or water source and another heat pump circuit using air heat. Furthermore, as long as it can exchange heat with the refrigerant in the heat source side heat exchanger, other substances (for example, gases including smoke, exhaust gas, various high-temperature gases, etc., or fluid solids including hot sand, dust, various particles, etc.) may be passed through the heat source side heat exchanger instead of the liquid, the outside air, or the water source, or heat from sunlight, reflected light, or other radiation may be supplied to the heat source side heat exchanger. [Explanation of symbols]

[0080] 1 Tank Unit 2. Hot water storage tank 3. Heat pump unit 4 Heating circulation circuit (hot water circulation circuit) 5. Heating supply pipe (supply pipe, hot and cold water piping) 6. Heating return pipe (return pipe, hot and cold water piping) 14 Compressor 15 Water-refrigerant heat exchanger (water-refrigerant heat exchanger) 16. Electronic expansion valve (pressure reducer) 17. Air heat exchanger 18 Refrigerant Piping 19. Heating circulation pump 20 Discharge temperature sensor 21 Outlet temperature sensor 22 Outdoor temperature sensor 23 Inlet water temperature sensor 30 Refrigerant circulation circuit 40. Hot water storage control device 50 Heating control device 100 Heat pump hot water system 410A Operation Switching Unit 410B Compressor control unit (compressor control means) 410C Expansion valve control unit (pressure reducer control means) 410Ca Operation Switching Determination Unit (Operation Switching Determination Means) 410Cb Target opening correction section (target opening correction means) 410Cc Target opening determination unit (target opening determination means) 410Cd Correction amount adjustment section (correction amount adjustment means) 410Ce Power suppression judgment unit (power suppression judgment means) Tair outside temperature Tout refrigerant discharge temperature T1 Inlet Water Temperature T2 outflow temperature

Claims

1. A heat pump system consisting of a compressor, pressure reducer, and air heat exchanger connected by refrigerant piping, A water-refrigerant heat exchanger receives a refrigerant from the heat pump device via the refrigerant piping and generates hot water for the hot water circulation circuit side through heat exchange with water, It has, In a heat pump hot water system capable of selectively performing operation in a normal mode in which hot water is generated on the hot water circulation circuit side with a predetermined normal output, and operation in a high-output mode in which hot water is generated on the hot water circulation circuit side with an output greater than the normal output, A compressor control means that controls the rotational speed of the compressor to increase or decrease to a target compressor rotational speed corresponding to each mode, depending on whether it is operating in the normal mode or the high-power mode. A pressure reducer control means for controlling the opening degree of the pressure reducer, It has, The pressure reducer control means is A target opening determination means for determining the target opening of the pressure reducer such that the discharge temperature of the refrigerant discharged from the compressor, or a value corresponding to the discharge temperature, becomes a target value calculated based on the target hot water temperature of the hot water produced, A means for determining whether or not a switch has been made from operation in the normal mode to operation in the high-power mode, When the operation switching determination means determines that a switch to operation in high-power mode has been performed, the target opening degree correction means adds a correction amount in the opening direction to the target opening degree determined by the target opening degree determination means, A power suppression determination means for determining whether or not a power suppression signal instructing the suppression of power consumption in the heat pump device has been input, A correction amount adjustment means adjusts the amount of correction in the opening direction by the target opening degree correction means to be smaller than the amount of correction in the opening direction when the power suppression determination means determines that the power suppression signal has been input, A heat pump hot water system characterized by having the following features.

2. The correction amount adjustment means is If the power suppression determination means determines that the power suppression signal has been input, the correction amount is adjusted variably according to the upper limit of power consumption that is permitted by the power suppression signal. The heat pump hot water device according to claim 1, characterized by the feature.

3. The correction amount adjustment means is If the power suppression determination means determines that the power suppression signal has been input, the correction amount is further adjusted variably according to the ambient temperature. The heat pump hot water device according to feature 2.

4. The correction amount adjustment means is If the power suppression determination means determines that the power suppression signal has been input, the correction amount is reduced to be smaller than when the power consumption upper limit is large if the power consumption upper limit is small, and the correction amount is reduced to be smaller than when the outside air temperature is high if the outside air temperature is low. The heat pump hot water device according to claim 3.

5. The aforementioned target opening degree correction means is After the operation switching determination means determines that the operation has been switched to the high-power mode, a correction amount in the opening direction is applied to the target opening determined by the target opening determination means, for a predetermined number of limited times. A heat pump hot water device according to any one of claims 1 to 4.

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