Storage-type water heater

Abstract

To secure the durability of a compressor even when power suppressing control and boil ending control are performed while being superimposed.SOLUTION: When an inflow water temperature T1 during operation in a boil ending operation mode is determined to satisfy a second temperature condition by a temperature condition determination part 410Be provided in a compressor control part 410B of a heating control device 50, a compressor 14 is stopped to end a boiling operation by an ending control part 410Bf. When a power suppression signal is determined to be input by a power suppression determination part 410Bd, the second temperature condition is changed into a condition for easily ending the boiling operation by a temperature condition change part 410Bg. This can prevent the durability of the compressor 14 from lowering while falling outside an operation possible pressure range because of a low rotating speed and a high discharge pressure of the compressor 14.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a hot water storage type water heater capable of boiling hot water in a hot water storage tank. [Background technology]

[0002] Conventionally, in this type of storage-type water heater, as described in Patent Document 1, the limiting current value of the compressor has been calculated from the compressor rotation speed, and the refrigerant discharge pressure of the compressor has been prevented from exceeding the limiting pressure value corresponding to the limiting current value. In addition, as described in Patent Document 2, there is also a system that performs end-of-boiling control by reducing the compressor rotation speed just before the end of boiling operation, thereby suppressing the increase in discharge pressure and making it possible to boil water with a relatively high supply water temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-33429 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-340402 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when the outside air temperature is high, such as in summer, the compressor rotation speed is low, and when the target boiling temperature is high, the discharge pressure also becomes high. In such a situation, if the inlet water temperature becomes high near the end of the boiling operation and the compressor rotation speed is reduced by the boiling end control as in Patent Document 2, the compressor falls outside the predetermined operable pressure range, which places a load on the compressor and shortens its lifespan.

[0005] In recent years, a configuration has been proposed for the heat pump device that operates by receiving power from, for example, a 100V AC household power source or a storage battery without providing a dedicated power source. In this case, the limited power supply capacity is shared between the heat pump device and various electrical appliances in a typical home, so a power suppression signal may be input from outside to instruct the heat pump device to suppress its power consumption. The power suppression signal indicates the upper limit of power consumption allowed in the heat pump device. 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, and the compressor rotation speed is limited.

[0006] When the end-of-boiling control is performed under such power suppression control, the durability of the compressor is further increased. In the above-mentioned Patent Document 1, damage to the compressor and other components is prevented and protected by limiting the refrigerant discharge pressure of the compressor, but no special consideration is given to the case where the power suppression control and the end-of-boiling control are performed simultaneously, which poses a problem in terms of ensuring the durability of the compressor. [Means for solving the problem]

[0007] In order to solve the above problems, claim 1 of the present invention provides a heat pump type heating means including a compressor, a water-refrigerant heat exchanger, a pressure reducer, and an evaporator, a heating circulation circuit that connects the hot water storage tank and a water-side flow path of the water-refrigerant heat exchanger of the heat pump type heating means in a circular manner, a circulation pump that circulates hot water in the heating circulation circuit, inlet water temperature detection means that detects the temperature of inlet water sent from the hot water storage tank to the water-refrigerant heat exchanger in the heating circulation circuit, boiling temperature detection means that detects the boiling temperature of water sent from the water-refrigerant heat exchanger to the hot water storage tank in the heating circulation circuit, outside air temperature detection means that detects outside air temperature, and control means that controls the compressor and the circulation pump, wherein the control means controls the compressor to have a predetermined first rotation speed and controls the flow rate of the circulation pump so that the boiling temperature detected by the boiling temperature detection means becomes a target boiling temperature in a normal boiling operation mode, or in the normal boiling operation mode, when the inlet water temperature detected by the inlet water temperature detection means reaches a target boiling temperature a final-boiling operation mode in which, when the first temperature condition is met, the compressor is controlled to a second rotation speed which is lower than the first rotation speed and the flow rate of the circulation pump is controlled to a flow rate higher than that in the normal boiling operation mode, and a storage-type water heater that performs boiling operation to heat hot water in the storage tank by either of these modes, the storage-type water heater comprises: a power reduction determination means that determines whether a power reduction signal instructing the heat pump heating means to reduce power consumption has been input; a temperature condition determination means that determines whether the inlet water temperature detected by the inlet water temperature detection means at the start of or after the start of the boiling operation in the final-boiling operation mode satisfies a second temperature condition for stopping operation; a termination processing means that stops the compressor and terminates the boiling operation when it is determined by the temperature condition determination means that the second temperature condition is met; and a temperature condition change means that changes the second temperature condition to a condition that makes it easier to terminate the boiling operation when it is determined by the power reduction determination means that the power reduction signal has been input.

[0008] In addition, in claim 2, the second temperature condition includes the inlet water temperature reaching a limit value that is variably set in response to at least one of the power indication value indicated by the power suppression signal, seasonal conditions, and the target boiling temperature.

[0009] In addition, in claim 3, the termination processing means stops the compressor at the timing when the power reduction determination means determines that the power reduction signal has been input and the temperature condition determination means determines that the first temperature condition is satisfied.

[0010] In addition, in claim 4, the temperature condition changing means changes the second temperature condition so as to advance the timing of ending the boiling operation. [Effects of the Invention]

[0011] According to claim 1 of this invention, when the temperature condition determination means determines that the inlet water temperature during the final boiling operation mode satisfies the temperature condition (second temperature condition) for stopping operation, the termination processing means stops the compressor and terminates the boiling operation. Then, when a power reduction signal is input by the power reduction determination means, the temperature condition change means changes the second temperature condition to a condition that makes it easier to terminate the boiling operation. This prevents the compressor from falling outside its operable pressure range due to low compressor rotation speed and high discharge pressure, which could reduce the compressor's durability. Furthermore, if there is another heating means other than the heat pump heating means that can heat the hot water in the hot water storage tank, the desired boiling temperature can be achieved by heating the hot water in the tank after the boiling operation has ended.

[0012] According to claim 2, the lower the power command value of the power suppression signal, the lower the compressor rotation speed is suppressed, and the compressor rotation speed is lower in summer because the outside air temperature is higher than in winter. Furthermore, the higher the target boiling temperature, the higher the compressor discharge pressure, resulting in a higher load on the compressor. Accordingly, according to claim 2, the limit value for the inlet water temperature is variably set in accordance with the power command value, seasonal conditions, target boiling temperature, etc., thereby reliably preventing a decrease in the durability of the compressor.

[0013] According to claim 3, the boiling operation is stopped immediately when the inlet water temperature satisfies the first temperature condition while the power reduction signal is input (in other words, when the operation mode switches from the normal boiling operation mode to the end-of-boiling operation mode). This makes it possible to quickly prevent a decrease in the durability of the compressor.

[0014] According to claim 4, the temperature condition changing means changes the second temperature condition so as to bring forward the timing of ending the boiling operation, thereby making it possible to reliably prevent a decrease in the durability of the compressor. [Brief explanation of the drawings]

[0015] [Figure 1] Schematic diagram of a hot water storage type water heater according to one embodiment of the present invention. [Figure 2] Functional block diagram showing the functional configuration of the heating control device [Figure 3] An explanatory diagram illustrating the switching behavior between normal boiling operation mode and end-of-boiling operation mode [Figure 4] 10 is an explanatory diagram showing an example of the behavior of the operation mode switching state, compressor rotation speed, boiling temperature, current consumption in the heat pump unit, discharge flow rate of the heating circulation pump, and inlet water temperature when switching from the normal boiling operation mode to the final boiling operation mode. [Figure 5]10A and 10B are explanatory diagrams showing examples of the behavior of the operation mode switching state, compressor rotation speed, boiling temperature, current consumption in the heat pump unit, discharge flow rate of the heating circulation pump, and inlet water temperature when switching from the normal boiling operation mode to the boiling end operation mode during power reduction control, and when the second temperature condition is changed by the method of one embodiment of the present invention and the boiling operation ends. [Figure 6] 1 is an explanatory diagram showing an operating range in which a predetermined durability of a compressor is guaranteed, and an operating range in which the durability is not guaranteed, respectively. [Figure 7] Table showing an example of limit value of inlet water temperature (boiling stop temperature) as the second temperature condition [Figure 8] Table showing another example of limit value of inlet water temperature (boiling stop temperature) as the second temperature condition [Figure 9] A flowchart showing a control procedure executed by the heating control device. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, an embodiment of the present invention will be described with reference to the drawings.

[0017] <Schematic circuit configuration> As shown in FIG. 1, the hot water storage type water heater 100 according to this embodiment includes a tank unit 1 having a hot water storage tank 2 for storing hot water, and a heat pump unit 3 (corresponding to a heat pump type heating means).

[0018] The heat pump unit 3 includes a water-refrigerant heat exchanger 15 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-refrigerant heat exchanger 15 has a refrigerant-side flow path 15b through which the refrigerant flows and a water-side flow path 15a, and exchanges heat between the high-temperature, 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 connected in a ring shape by a heating forward pipe 5 and a heating return pipe 6, and a heating circulation circuit 4 is formed between the tank unit 1 and the heat pump unit 3.

[0019] The heating supply pipe 5 is connected to the bottom of the hot water storage tank 2, and the heating return pipe 6 is connected to the top of the hot water storage tank 2. The heating circulation pump 19 is provided midway along the heating supply pipe 5, and circulates the hot water in the hot water storage tank 2 while circulating the hot water from the heating supply pipe 5 to the heating return pipe 6 via the water-side flow path 15a. The heating supply pipe 5 is provided with an inlet water temperature sensor 23 (corresponding to an inlet water temperature detection means) that detects an inlet water temperature T1 (hot water inlet temperature) of the water sent from the hot water storage tank 2 to the water-side flow path 15a of the water-refrigerant heat exchanger 15, and the heating return pipe 6 is provided with a boiling temperature sensor 24 (corresponding to a boiling temperature detection means) that detects a boiling temperature Tb of the water sent from the water-side flow path 15a to the hot water storage tank 2.

[0020] In the tank unit 1, a plurality of hot water temperature sensors 12 are provided on the side surface of the hot water tank 2, extending from top to bottom, for detecting the temperature Tw of hot water at each corresponding location in the hot water tank 2. A water supply pipe 7 that supplies water to the hot water storage tank 2 is also connected to the bottom of the hot water storage tank 2, and a hot water outlet pipe 8 that discharges the stored high-temperature water is also connected to the top of the hot water storage tank 2. The hot water outlet pipe 8 is provided with a negative pressure intake valve 119 that opens to introduce air into the hot water storage tank 2 when negative pressure occurs inside the hot water storage tank 2, and a water supply bypass pipe 9 branches off from the water supply pipe 7. Furthermore, there is provided a mixing valve 10 that mixes hot water from the hot water outlet pipe 8 with water from the water supply bypass pipe 9 to produce hot water at the set hot water supply temperature, a hot water supply pipe 108a that supplies the hot water mixed by the mixing valve 10 to the hot water supply terminal 125, and a hot water supply temperature sensor 11 that detects the hot water temperature in the hot water supply pipe 108a.

[0021] In addition, 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 capable of heating the hot water mixed in the mixing valve 10 is provided between these hot water supply pipes 108a and 108b.

[0022] The heat pump unit 3 also includes a compressor 14 that compresses the refrigerant, an electronic expansion valve 16 as a pressure reducer that reduces the pressure of the refrigerant after passing through the water-refrigerant heat exchanger 15, an air heat exchanger 17 as an evaporator that exchanges heat between the refrigerant and air that serves as a heat source, and an outdoor fan 67 that sends outside air to the air heat exchanger 17. The compressor 14, a 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 circular shape by refrigerant piping 18, thereby forming a refrigerant circulation circuit 30.

[0023] Refrigerant piping 18 connects the discharge side of compressor 14 to the inlet side of the water-refrigerant heat exchanger 15, and also connects the suction side of compressor 14 to the outlet side of the air heat exchanger. In this embodiment, no dedicated power supplies are provided for the heat pump unit 3 and the tank unit 1, and both the heat pump unit 3 and the tank unit are configured to operate by receiving power from, for example, an AC 100V household power source or a storage battery.

[0024] A heat pump cycle is formed in the refrigerant circulation circuit 30, using, for example, an R32 refrigerant as a refrigerant. A discharge temperature sensor 20 is provided at a portion of the refrigerant piping 18 on the discharge side of the compressor 14 to detect a refrigerant discharge temperature Tout of the refrigerant discharged from the compressor 14, an outflow temperature sensor 21 is provided at the refrigerant piping 18 between the refrigerant-side flow path 15b and the electronic expansion valve 16 to detect an 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, and an outside air temperature sensor 22 (corresponding to outside air temperature detection means) is provided at the air inlet side of the air heat exchanger 17 to detect an outside air temperature Tair.

[0025] The tank unit 1 is provided with a hot water storage control device 40 to which the detection results of the sensors 12 and 11 are input. Similarly, the heat pump unit 3 is provided with a heating control device 50 to which the detection results of the 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 that they can communicate with each other, and control the operation of each device in the tank unit 1 and the heat pump unit 3 while coordinating with each other based on the detection results of the sensors 12, 11, 20, 22, 24, 21, and 23. The heating control device 50 and the hot water storage control device 40 correspond to control means.

[0026] Note that there may be a master-slave relationship in terms of control between the heating control device 50 and the hot water storage control device 40, where, 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. In the following, this specification will be described taking such a case as an example.

[0027] <Heat pump power consumption detector> 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, and the same applies in the drawings). 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.

[0028] <Heating control device> Next, we will explain the heating control device 50 provided in the heat pump unit 3. Although detailed illustrations are omitted, the heating control device 50 includes a storage unit that stores various data and programs, and a control unit that performs calculation and control processing. The functional configuration of this heating control device 50 will be explained with reference to Figure 2.

[0029] As shown in FIG. 2, the heating control device 50 functionally includes an operation switching unit 410A, a compressor control unit 410B, an expansion valve control unit 410C, an outdoor fan control unit 410D, and a pump control unit 410F.

[0030] The operation switching unit 410A receives an operation command and a power suppression signal (described in detail below) output by the hot water storage control device 40. In response to the operation command, the operation switching unit 410A determines whether or not to perform a boiling operation (described below) that causes the air heat exchanger 17 to function as an evaporator. The operation switching unit 410A also 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. Note that this operation information includes the temperature Tw of the hot water in the hot water storage tank 2 detected by the hot water temperature sensor 12, an appropriately determined target boiling temperature Tbo, and the like.

[0031] In this example, the compressor control unit 410B receives 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 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, the power reduction 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 below). The compressor control unit 410B also has an operation mode determination unit 410Ba, a maximum rotation speed setting unit 410Bb, a target rotation speed determination unit 410Bc, a power reduction determination unit 410Bd, a temperature condition change unit 410Bg, a temperature condition determination unit 410Be, and a termination control unit 410Bf.

[0032] The operation mode determination unit 410Ba determines, based on the inlet water temperature T1 from the inlet water temperature sensor 23, whether to operate in the normal boiling operation mode or the end-of-boiling operation mode, which are pre-prepared for the heat pump unit 3 of this embodiment.

[0033] That is, the normal boiling operation mode is a mode in which the rotation speed of the compressor 14 is controlled to a predetermined target rotation speed (corresponding to a first rotation speed) based on the outside air temperature Tair detected by the outside air temperature sensor 22 and the target boiling temperature Tbo, and the rotation speed of the heating circulation pump 19 is increased or decreased so that the boiling temperature Tb detected by the boiling temperature sensor 24 matches the target boiling temperature Tbo. The pump discharge flow rate of the heating circulation pump 19 at this time will be referred to as a "first flow rate" hereinafter as appropriate. The end-of-boiling operation mode is a mode in which, when the inlet water temperature T1 detected by the inlet water temperature sensor 23 during operation in the normal boiling operation mode satisfies the temperature condition before the end of boiling (corresponding to the first temperature condition), the target rotation speed of the compressor 14 is controlled to be a rotation speed (second rotation speed) lower than the first rotation speed, and the discharge flow rate of the heating circulation pump 19 is controlled to be a flow rate (hereinafter referred to as the second flow rate) higher than the flow rate (first flow rate) in the normal boiling operation mode. The result of the operation mode determination by the operation mode determination unit 410Ba is input to the pump control unit 410F.

[0034] The maximum rotation speed setting unit 410Bb determines the maximum value of the target rotation speed (maximum target rotation speed) of the corresponding compressor 14 based on the result of the operation mode determination by the operation mode determination unit 410Ba. The target rotation speed determination unit 410Bc sets a target rotation speed of the compressor 14 based on the input outside air temperature Tair, the boiling temperature Tb, and the power suppression signal within the range of the maximum target rotation speed set by the maximum rotation speed setting unit 410Bb as described above, and controls the rotation speed of the compressor 14 to increase or decrease so as to achieve this target rotation speed.

[0035] A specific method for switching between the normal boiling operation mode and the final boiling operation mode is shown in FIG. 3. In this example, the first temperature condition is defined by the difference between the target boiling temperature Tbo and the inlet water temperature T1. That is, when the difference between Tbo and T1 decreases to Tbo-T1=15°C during operation while the operation mode is switched to the normal boiling operation mode by the operation mode determination unit 410Ba, the operation mode determination unit 410Ba switches from the normal boiling operation mode to the final boiling operation mode. As a result, the maximum rotation speed setting unit 410Bb and the target rotation speed determination unit 410Bc control the target rotation speed of the compressor 14 from the first rotation speed to the second rotation speed, which is smaller than the first rotation speed.

[0036] Conversely, if the difference between Tbo and T1 increases to Tbo - T1 = 17°C during operation in the end-of-boiling operation mode, the operation mode determination unit 410Ba switches from the end-of-boiling operation mode to the normal boiling operation mode. As a result, the target rotation speed of the compressor 14 is controlled by the maximum rotation speed setting unit 410Bb and the target rotation speed determination unit 410Bc so as to change from the second rotation speed to the first rotation speed, which is greater than the second rotation speed.

[0037] The power restriction determination unit 410Bd (corresponding to the power restriction determination means), temperature condition determination unit 410Be (corresponding to the temperature condition determination means), termination control unit 410Bf, and temperature condition change unit 410Bg provided in the compressor control unit 410B will be described later.

[0038] In this example, the expansion valve control unit 410C receives the refrigerant discharge temperature Tout detected by the discharge temperature sensor 20 and the operation information corresponding to the operation command of the hot water storage control device 40. In this example, the expansion valve control unit 410C controls the opening degree of the electronic expansion valve 16 to increase or decrease so that the refrigerant discharge temperature Tout becomes a desired target temperature for control.

[0039] 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. The outdoor fan control unit 410D sets a target rotation speed of the outdoor fan 67 based on the input operation information and the outdoor air temperature Tair, and controls the rotation speed of the outdoor fan 67 to increase or decrease so that it reaches the target rotation speed.

[0040] The pump control unit 410F receives the boiling temperature Tb detected by the boiling temperature sensor 24 and the operation information (including the target boiling temperature Tbo) corresponding to the operation command from the hot water storage control device 40, and controls the rotation speed of the heating circulation pump 19 based on these information so that the boiling temperature Tb coincides with the target boiling temperature Tbo. As already mentioned, the operation mode determined by the operation mode determination unit 410Ba of the compressor control unit 410B is also input to the pump control unit 410F. As a result, when the operation mode determination unit 410Ba switches from the normal boiling operation mode to the end-of-boiling operation mode, the rotation speed is increased so that the discharge rate of the heating circulation pump 19 becomes a larger flow rate than the previous flow rate. Conversely, when the operation mode determination unit 410Ba switches from the end-of-boiling operation mode to the normal boiling operation mode, the rotation speed is decreased so that the discharge rate of the heating circulation pump 19 becomes a smaller flow rate than the previous flow rate.

[0041] <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 17, 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, in the water-refrigerant heat exchanger 15, heat is released by heat dissipation from the refrigerant in the refrigerant pipe 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 hot water generation operation).

[0042] <Switching to end-of-boiling operation> For example, as shown schematically in FIG. 4, when the normal boiling operation mode is selected by the operation mode determination unit 410Ba during the boiling operation, the rotation speed N of the compressor 14 is controlled to be the first rotation speed N1 as described above, and the rotation speed of the heating circulation pump 19 is controlled so that the pump discharge flow rate V becomes the first flow rate V1. Then, after operation in this normal boiling operation mode is performed for a certain period of time, the boiling of the hot water in the hot water storage tank 2 progresses, and when the inlet water temperature T1 satisfies the first temperature condition, the operation mode determination unit 410Ba switches to the boiling end operation mode at timing to. As a result, the rotation speed N of the compressor 14 is controlled to the second rotation speed N2, which is lower than before, and the pump discharge flow rate V of the heating circulation pump 19 is controlled to the second flow rate V2, which is higher than before, as a result of the control to match the boiling temperature Tb with the target boiling temperature Tbo. As a result, even if the temperature of the hot water circulating in the heating circulation circuit 4 becomes relatively high, the boiling temperature Tb can be maintained approximately constant while suppressing an increase in the discharge pressure of the compressor 14, and boiling can be continued. Furthermore, as a result of the increase in the pump discharge flow rate V of the heating circulation pump 19, in other words, the increase in the pump rotation speed, the current consumption I (here, this is explained as current consumption, but it can also be power consumption) in the heat pump unit 3 after switching to the end-of-boiling operation mode increases significantly compared to the normal boiling operation mode.

[0043] <Concerns regarding boil-off operation> Here, for example, when the outside air temperature Tair is high, as in summer, the rotation speed of the compressor 14 during boiling operation is reduced, and when the target boiling temperature Tbo is high, the discharge pressure of the compressor 14 is increased. In such a state, if the inlet water temperature T1 becomes high near the end of the boiling operation, the operation mode is switched to the end-of-boiling operation mode, and the rotation speed of the compressor 14 is reduced, an excessive load is placed on the compressor 14, which may shorten the life of the compressor 14.

[0044] <Power suppression control> On the other hand, when the compressor 14 and other components of the heat pump unit 3 operate by receiving power from a household power source or a storage battery as described above, the limited power capacity is shared with the tank unit 1 and various household electrical appliances. Therefore, in this embodiment, a power reduction signal instructing reduction in power consumption in the compressor 14 and other components is input from the hot water storage control device 40 to the operation switching unit 410A and compressor control unit 410B of the heating control device 50 as described above. The power reduction signal indicates an upper limit of power consumption permitted to be consumed by the compressor 14 and other components.

[0045] As described above, the compressor control unit 410B is provided with a power restriction determination unit 410Bd. This power restriction determination unit 410Bd determines whether or not the power restriction signal has been input. If it is determined that the power restriction signal has been input, the power restriction determination unit 410Bd outputs the value of the power consumption upper limit specified by the power restriction signal to the target rotation speed determination unit 410Bc. The target rotation speed determination unit 410Bc sets a 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 a range in which 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 controls the rotation speed of the compressor 14 to increase or decrease so as to achieve this target rotation speed.

[0046] <Concerns about switching to end-of-boil operation mode during power reduction control> However, when the normal boiling operation mode is switched to the end-of-boiling operation mode while the power suppression control described above is being performed, the target rotation speed of the compressor 14 is further restricted by the power suppression control in addition to the state in which the target rotation speed determination unit 410Bc of the compressor control unit 410B restricts the rotation speed of the compressor 14 to the second target rotation speed, as described above.

[0047] FIG. 5(a), which corresponds to FIG. 4, shows an example of behavior when switching from the normal boiling operation mode to the end-of-boiling operation mode during power restriction control. In the example of FIG. 5(a), when the inlet water temperature T1 rises to satisfy the condition Tbo-T1=15°C at time t0, the normal boiling operation mode is switched to the end-of-boiling operation mode. This reduces the rotation speed N of the compressor 14, and the rotation speed of the heating circulation pump 19 is increased to maintain the boiling temperature Tb at the target boiling temperature Tbo, thereby increasing the pump discharge flow rate V. As a result, the rotation speed N of the compressor 14 is further reduced to prevent an increase in the current consumption I even when the rotation speed of the heating circulation pump 19 increases. This behavior is repeated, resulting in a downward trend in the rotation speed N of the compressor 14, as shown in the figure. This further increases concerns about the durability of the compressor 14, as described above.

[0048] That is, as shown in Figure 6, if the rotation speed of compressor 14 is plotted on the horizontal axis and the discharge pressure from compressor 14 on the vertical axis, the lower right side is typically the operating range in which a predetermined durability of compressor 14 is guaranteed, and the upper left side is the operating range in which that predetermined durability is not guaranteed. These two ranges are separated by boundary line k. As described above, when the end-of-boil operation mode is superimposed during power reduction control, the increase in discharge pressure in response to an increase in inlet water temperature T1 also acts, and the operating point of compressor 14 shifts from c1 to c2 to c3 to c4 to c5 as inlet water temperature T1 increases, eventually crossing boundary line k to c6, entering an operating range in which the durability of compressor 14 is not guaranteed.

[0049] <End of boiling operation process> Therefore, in this embodiment, the compressor control unit 410B is provided with the temperature condition determination unit 410Be, termination control unit 410Bf, and temperature condition change unit 410Bg.

[0050] <Temperature condition judgment section> The temperature condition determination unit 410Be determines whether the inlet water temperature T1 detected by the inlet water temperature sensor 23 satisfies a predetermined temperature condition (corresponding to the second temperature condition) for stopping the boiling operation at the start or after the start (in other words, during the operation) of the boiling operation in the boiling end operation mode as described above. This determination is made regardless of whether the power restriction determination unit 410Bd determines that the power restriction signal has been input.

[0051] <End control section> When the temperature condition determination unit 410Be determines that the second temperature condition is satisfied, the termination control unit 410Bf performs processing to stop the compressor 14 and terminate the boiling operation. In other words, the second temperature condition is also a boiling termination condition. <Temperature condition change section> When the power restriction signal is input by the power restriction determination unit 410Bd, the temperature condition change unit 410Bg changes the second temperature condition used for determination by the temperature condition determination unit 410Be to a condition that makes it easier to end the boiling operation. An example of the second temperature condition when no change is made by the temperature condition change unit 410Bg, and an example of the second temperature condition when change is made by the temperature condition change unit 410Bg are shown in Figure 7.

[0052] 7, the left column shows an example in which the power restriction signal is not input and the change is not made (indicated as "no power restriction"). In this example, the second temperature condition is that the temperature Tw detected by the sensor 12 at a predetermined position (for example, the lowest position) among the multiple hot water temperature sensors 12 provided in the hot water storage tank 2 is higher than the target boiling temperature Tbo by: Tw≧Tbo-5[℃] (Formula 1) The state where the above condition is satisfied continues for a predetermined period (5 seconds in this example), or the inlet water temperature T1 is higher than the target boiling temperature Tbo. T1≧Tbo-5[℃] (Formula 2) The condition that satisfies the above condition continues for a predetermined period (5 seconds in this example).

[0053] On the other hand, the right column of FIG. 7 shows an example where the power suppression signal is input and the change is made (denoted as "power limit"). In this example, the power consumption upper limit value (corresponding to the power instruction value) indicated by the power suppression signal is 550 [VA] and 450 [VA]. The second temperature condition in this example is that the inlet water temperature T1 reaches the boiling stop temperature (corresponding to the limit value) represented by the numerical values ​​shown. As shown in the figure, the boiling stop temperature is set to be variable in response to at least one of the power consumption upper limit value, seasonal conditions (summer or spring / fall), and target boiling temperature Tbo (in this example, it is set to be variable in response to all of them).

[0054] In the case where the power consumption upper limit is 550 VA, in the summer, if the target boiling temperature Tbo = 50°C, the boiling stop temperature is set to 40°C, and if the target boiling temperature Tbo = 55°C, the boiling stop temperature is set to 25°C. In the spring and autumn, if the target boiling temperature Tbo = 50°C, the boiling stop temperature is set to 35°C, and if the target boiling temperature Tbo = 55°C, the boiling stop temperature is set to 20°C. Note that the summer and spring and autumn seasons can be identified, for example, by a calendar means appropriately provided in the hot water storage control device 40, the heating control device 50, etc., which identifies June, July, and August as summer and March, April, May, September, October, and November as spring and autumn. Alternatively, the temperature at an appropriate location in the circuit shown in Figure 1 that is less affected by the operating state (for example, the water supply temperature in the water supply pipe 7 or the water supply bypass pipe 9) may be used as a representative temperature, and identification may be performed by comparing this with a predetermined threshold value.

[0055] When the power consumption upper limit is 450 [VA], in summer, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 30 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 20 [°C]. In spring and autumn, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 25 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 15 [°C].

[0056] In addition, in order to more quickly stop the compressor 14 by the termination control unit 410Bf (for example, to immediately stop the compressor 14 when the temperature condition determination unit 410Be determines that the second temperature condition is satisfied), the boiling stop temperature (limit value) may be set to an extremely low value, for example, as shown in Figure 8. In the illustrated example, when the power consumption upper limit is 550 [VA], in summer, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 3 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 1 [°C]. In spring and autumn, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 2 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 1 [°C]. When the power consumption upper limit is 450 [VA], in summer, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 2 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 1 [°C]. In spring and autumn, if the target boiling temperature Tbo = 50 [°C], the boiling stop temperature is set to 1 [°C], and if the target boiling temperature Tbo = 55 [°C], the boiling stop temperature is set to 1 [°C]. For example, by setting it as described above, the compressor 14 can be immediately stopped when the normal boiling operation mode is switched to the end-of-boiling operation mode (in other words, the operation in the end-of-boiling operation mode is not actually performed).

[0057] In addition, each value of the boiling stop temperature that is variably set as described above is stored in an appropriate memory means provided, for example, in the hot water storage control device 40 or the heating control device 50, in the form of a table as shown in Figures 7 and 8, or in other form such as a graph.

[0058] Figure 5(b), which corresponds to Figure 5(a), shows an example of the behavior when switching from normal boiling operation mode to end-of-boiling operation mode during power suppression control, which is performed by the temperature condition determination unit 410Be and the termination control unit 410Bf when the above-mentioned change is made by the temperature condition change unit 410Bg.

[0059] As shown in Figure 5(b), as a result of the change made by the temperature condition change unit 410Bg as described above, at the time when the operation mode is switched to the end of boiling (time to), the inlet water temperature T1 reaches the boiling stop temperature illustrated in Figure 7 and the second temperature condition is satisfied, so that the compressor 14 is then promptly stopped and the boiling operation is stopped.

[0060] <Control procedure> The control procedure executed by the heating control device 50 of this embodiment to realize the above method will be described with reference to the flowchart of FIG.

[0061] 9, this flow starts in the operating state in the normal boiling operation mode. That is, the operation mode determination unit 410Ba determines operation in the normal boiling operation mode, and based on the determination result, the compressor 14 is controlled to the first rotation speed via the maximum rotation speed setting unit 410Bb and the target rotation speed determination unit 410Bc. In addition, the rotation speed is controlled by the pump control unit 410F so that the discharge rate of the heating circulation pump 19 becomes the first flow rate. First, in S10, operation mode determination unit 410Ba determines whether inlet water temperature T1 from inlet water temperature sensor 23 satisfies the condition for switching to the end-of-boiling operation mode (end-of-boiling condition). In the example shown in Figure 3, it determines whether the difference between Tbo and T1 has decreased to Tbo - T1 = 15°C. If the end-of-boiling condition is not met, the determination is No, and the process proceeds to S20.

[0062] In S20, the operation in the normal boiling operation mode that has been started as described above continues. That is, as described above, the compressor 14 is controlled to have the first rotation speed, and the rotation speed is controlled so that the discharge rate of the heating circulation pump 19 becomes the first flow rate.

[0063] Thereafter, in S30, the operation mode determination unit 410Ba determines whether the boiling end condition (second temperature condition) is met.

[0064] If the boiling end condition is met, S30 is judged as Yes, and the process proceeds to S70 (described later). If the boiling end condition is not met, S30 is judged as No, and the process returns to S10 and the same procedure is repeated, and boiling operation in the normal boiling operation mode continues.

[0065] Thereafter, if the end-of-boiling condition is met in S10, a Yes determination is made, and the process proceeds to S40. In S40, operation in the end-of-boiling operation mode is initiated. That is, the operation mode determination unit 410Ba determines operation in the end-of-boiling operation mode, and based on the determination result, the compressor 14 is controlled to the second rotation speed via the maximum rotation speed setting unit 410Bb and the target rotation speed determination unit 410Bc. In addition, the pump control unit 410F controls the rotation so that the discharge rate of the heating circulation pump 19 becomes the second flow rate.

[0066] Then, in S60, the power restriction determination unit 410Bd determines whether the power restriction signal has been input. If the power restriction signal has not been input, the determination is No, and the process proceeds to S30, where the same procedure is repeated, and boiling operation in the end-of-boiling operation mode continues. If the power restriction signal has been input, the determination is Yes, and the process proceeds to S65.

[0067] In S65, the temperature condition change unit 410Bg changes the second temperature condition. For example, in the example shown in Figure 7, the condition described in the "No power limit" column on the left (Equation (1) and Equation (2) hold) is changed to the condition described in the "Power limit" column on the right (inlet water temperature T1 reaches the limit value shown). Thereafter, the process proceeds to S30, where the same procedure is repeated, and boiling operation in the final boiling operation mode continues.

[0068] In S70, operation mode determination unit 410Ba stops operation of compressor 14, and the boiling operation is stopped. At this time, pump control unit 410F also stops driving heating circulation pump 19. The function of heating control device 50 to stop heating circulation pump 19 and compressor 14 corresponds to the termination processing means.

[0069] <Effects of the embodiment> As described above, according to this embodiment, if the temperature condition determination unit 410Be determines that the inlet water temperature T1 during the end-of-boiling operation mode satisfies the second temperature condition for stopping operation, the termination control unit 410Bf stops the compressor 14 and terminates the boiling operation. If the power reduction determination unit 410Bd determines that a power reduction signal has been input, the temperature condition change unit 410Bg changes the second temperature condition to a condition that makes it easier to terminate the boiling operation. This prevents the compressor 14 from falling outside the operable pressure range due to a low rotation speed and high discharge pressure, which could reduce the durability of the compressor 14. After the boiling operation is completed, the insufficient heating can be appropriately compensated for by heating using another auxiliary heating means.

[0070] Furthermore, typically, the lower the power consumption upper limit value indicated by the power curtailment signal, the lower the rotation speed of compressor 14 is suppressed, and since the outside air temperature is higher in summer than in winter, the rotation speed of compressor 14 is lower. Furthermore, the higher the target boiling temperature Tbo, the higher the discharge pressure of compressor 14, and the higher the load on compressor 14. In response to this, particularly in this embodiment, as illustrated in Figure 7, the boiling stop temperature is variably set in accordance with the power indication value, seasonal conditions, and target boiling temperature Tbo, so that a decrease in the durability of compressor 14 can be reliably prevented.

[0071] In this embodiment, the boiling stop temperature corresponding to the power consumption upper limit, seasonal conditions, target boiling temperature Tbo, etc. is stored in advance in the storage means. By reading out the boiling stop temperature stored in the storage means, deterioration of the durability of the compressor 14 can be prevented with simple and quick control.

[0072] 8, the boiling operation is immediately stopped when the inlet water temperature T1 satisfies the first temperature condition (in other words, when the normal boiling operation mode is switched to the end-of-boiling operation mode) while the power suppression signal is input. This makes it possible to quickly prevent a decrease in the durability of the compressor 14 (without actually operating in the end-of-boiling operation mode).

[0073] In particular, in this embodiment, the temperature condition changing unit 410Bg changes the second temperature condition so as to hasten the end timing of the boiling operation, thereby reliably preventing the durability of the compressor 14 from decreasing.

[0074] The present invention is not limited to the above embodiments, and can be applied within the scope of the present invention.

[0075] That is, in the above description, the hot water storage tank 2 is connected to the load side of the water-refrigerant heat exchanger 15 via the heating circulation circuit 4 consisting of the heating supply pipe 5 and the 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, this is not limited to this. That is, heating operation as a hot water generating 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 for heating. In this case, the target return temperature corresponding to the temperature setting level of a remote control that operates the heat exchange terminal, for example, corresponds to the target boiling temperature. In this case, the same effect can be obtained by the same method as described above.

[0076] The heat pump cycle in the above embodiment may be an ejector cycle using an ejector as a pressure reducer.

[0077] In the above embodiment, the heat source unit is an air-source heat pump that has an outdoor fan 67 that blows outside air while passing a refrigerant through the air heat exchanger 17 as a heat source-side heat exchanger, and exchanges heat between the outside air as a heat source and the refrigerant, but the present invention is not limited to this. That is, the heat source unit may be configured such that water or antifreeze liquid is supplied to the heat source-side heat exchanger, and the liquid exchanges heat with the refrigerant in the heat source-side heat exchanger. Alternatively, a heat source-side heat exchanger may be provided underground or in a relatively large-capacity water source, and heat may be exchanged between the underground or the water source and the refrigerant through the heat source-side heat exchanger.Furthermore, a combined heat source configuration may be provided, which includes a heat pump circuit using heat from the underground or the water source and another heat pump circuit using air heat. Furthermore, in place of the liquid, the outside air, or the water source, other substances (for example, gases including smoke, exhaust fumes, and various high-temperature gases, or fluid solids including hot sand, dust, and various particles) may be passed through the heat source side heat exchanger, as long as they are capable of exchanging heat with the refrigerant in the heat source side heat exchanger, or heat from sunlight, reflected light, or other radiation may be supplied to the heat source side heat exchanger. [Explanation of symbols]

[0078] 1 Tank Unit 2 Hot water tank 3 Heat pump unit (heat pump type heating means) 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 (circulation pump) 20 Discharge temperature sensor 21 Outlet temperature sensor 22 Outside air temperature sensor (outside air temperature detection means) 23 Inlet water temperature sensor (inlet water temperature detection means) 24 Boiling temperature sensor (boiling temperature detection means) 30 Refrigerant circulation circuit 40 Hot water storage control device (control means) 50 Heating control device (control means) 100 Storage water heater 410A Operation Switching Unit 410B Compressor control unit 410Bd Power suppression determination unit (power suppression determination means) 410Be Temperature condition judgment section (temperature condition judgment means) 410Bf End control section 410Bg Temperature condition change unit (temperature condition change means) Tair Outside temperature Tout Refrigerant discharge temperature T1 Inlet water temperature T2 Outflow temperature

Claims

1. A hot water storage tank for storing hot water; a heat pump type heating means including a compressor, a water-refrigerant heat exchanger, a pressure reducer, and an evaporator; a heating circulation circuit that connects the water-side flow path of the water-refrigerant heat exchanger of the heat pump type heating means and the hot water storage tank in a circular manner; a circulation pump that circulates hot water in the heating circulation circuit; an inlet water temperature detection means for detecting the temperature of inlet water sent from the hot water storage tank to the water-refrigerant heat exchanger in the heating circulation circuit; a boiling temperature detection means for detecting a boiling temperature of water sent from the water-refrigerant heat exchanger to the hot water storage tank in the heating circulation circuit; an outside air temperature detection means for detecting an outside air temperature; a control means for controlling the compressor and the circulation pump; and The control means In a hot water storage type water heater that performs a boiling operation to heat hot water in the hot water storage tank by either a normal boiling operation mode in which the compressor is controlled to a predetermined first rotation speed and the flow rate of the circulation pump is controlled so that the boiling temperature detected by the boiling temperature detection means becomes a target boiling temperature, or a boiling end operation mode in which, in the normal boiling operation mode, when the inlet water temperature detected by the inlet water temperature detection means satisfies a first temperature condition before the end of boiling, the compressor is controlled to a second rotation speed which is smaller than the first rotation speed and the flow rate of the circulation pump is controlled to a flow rate which is larger than that in the normal boiling operation mode, a power reduction determination means for determining whether a power reduction signal instructing reduction of power consumption in the heat pump heating means has been input; a temperature condition determination means for determining whether the inlet water temperature detected by the inlet water temperature detection means satisfies a second temperature condition for stopping operation at the start of or after the start of the boiling operation in the boiling end operation mode; a termination processing means for stopping the compressor and terminating the boiling operation when the temperature condition determination means determines that the second temperature condition is satisfied; a temperature condition changing means for changing the second temperature condition to a condition that makes it easier to end the boiling operation when the power reduction determination means determines that the power reduction signal has been input; A hot water storage type water heater characterized by having:

2. The second temperature condition is The inlet water temperature reaches a limit value that is variably set in response to at least one of the power indication value indicated by the power suppression signal, seasonal conditions, and a target boiling temperature.

2. The hot water storage type water heater according to claim 1.

3. The termination processing means The compressor is stopped at a timing when the power reduction determining means determines that the power reduction signal has been input and when the temperature condition determining means determines that the first temperature condition is satisfied.

2. The hot water storage type water heater according to claim 1.

4. The temperature condition changing means The second temperature condition is changed so that the timing of ending the boiling operation is advanced.

3. The hot water storage type water heater according to claim 1 or 2.

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