Heat pump water heater

Abstract

To avoid generation of overload of a drive motor due to non-rotation of an impeller at start of an unfreezing operation after freezing.SOLUTION: A heating control device 50 receives an unfreezing instruction via an operation switch while drain plugs D1, D2 of a heating return pipe 6 remain open when air vent of a hot water storage tank 2 and a heating circulation circuit 4 could not be completed (S10), starts an unfreezing operation for supplying a refrigerant heated by a refrigerant circulation circuit 30 to a water refrigerant heat exchanger 15 (S20), and drives a heating circulation pump 19 (S30) after waiting in a predetermined period after staring of the unfreezing operation (S25). Due to this, since the driving of the heating circulation pump 19 is started after melting of a frozen portion around an impeller is sufficiently progressed, generation of overload of a drive motor due to non-rotation of the impeller can be avoided.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a heat pump water heater. [Background technology]

[0002] Conventionally, in this type of heat pump water heater, as described in Patent Document 1, if there is a possibility that the water heat exchanger has frozen between the completion of the previous hot water storage operation and the start of the current hot water storage operation, a thawing hot water storage operation is performed at the start of the hot water storage operation, in which hot water is stored in the hot water storage tank while the water heat exchanger is thawed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-184144 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional system, during the defrosting hot water storage operation, a process of starting the heat pump to heat the water heat exchanger and a process of starting the circulation pump thereafter are carried out successively. If a heat pump water heater will not be used for an extended period of time, it may be possible to drain the water from the hot water storage tank, water heat exchanger, circulation pump, and the piping connecting them to prevent damage due to freezing. However, even if the water is drained, the remaining water in the water heat exchanger and circulation pump may freeze. In particular, if the remaining water in the circulation pump freezes, the impeller in the circulation pump may become locked. Therefore, if the conventional defrost hot water storage operation is performed under such circumstances, there is a problem that starting the circulation pump may cause an overload on the pump's drive motor, which may lead to a malfunction. [Means for solving the problem]

[0005] In order to solve the above problems, claim 1 of the present invention provides a hot water circulation circuit including a hot water storage tank for storing hot water, a heat pump type heating means for heating a refrigerant, a heat exchanger for exchanging heat between the refrigerant heated by the heating means and the hot water in the hot water storage tank, a forward pipe from the bottom of the hot water storage tank to the heat exchanger, and a return pipe from the heat exchanger to the top of the hot water storage tank; A circulation pump that circulates the hot and cold water in the hot and cold water circulation circuit; The return pipe downstream and below the heat exchanger and the circulating pump Established in When open, air can be removed from inside the pipe. Drain valve installed in D1 and ,before The heating means and the circulation pump are controlled, and the circulation pump is driven while heating is being performed by the heating means, whereby the hot water introduced into the heat exchanger through the forward pipe and heated by heat exchange with the refrigerant is returned to the hot water storage tank through the return pipe. fart A heat pump type hot water heater having a control means for performing a boiling operation to supply hot water, The opening is also provided when water is refilled to remove air from the hot water storage tank and the hot water circulation circuit. State of the drain plug D1 No water flows out from 、 When freezing occurs in the heat exchanger, a thawing command is sent. The user The control means has an executable operating means, and executes a thawing instruction reception process that receives the thawing instruction via the operating means, a thawing operation start process that controls the heating means and starts a thawing operation in which heated refrigerant is supplied to the heat exchanger when the thawing instruction is received by the thawing instruction reception process, a standby process that waits for a predetermined period of time after the thawing operation is started by the thawing operation start process, and a pump drive process that drives the circulating pump after waiting for the predetermined period of time by the standby process.

[0006] In addition, in claim 2, the control means further controls the heating means when a predetermined condition is satisfied, and executes a thawing operation stop process to terminate the thawing operation started by the thawing operation start process.

[0007] In addition, in claim 3, the predetermined condition is that the temperature detected by the hot and cold water temperature detection means provided in the return pipe is equal to or higher than a predetermined first threshold value, and the rotation speed of the circulation pump is equal to or higher than a predetermined second threshold value.

[0008] In claim 4, the operating means is a switch provided on an outdoor unit that includes the heating means. Effect of the Invention

[0009] According to claim 1 of this invention, the hot water storage tank and the heat exchanger are connected by the forward pipe and the return pipe of the hot water circulation circuit, and in the heat exchanger, heat exchange is performed between the refrigerant heated by the heat pump type heating means and the hot water in the hot water storage tank. That is, under the control of the control means, the circulation pump is driven while heating is performed by the heating means, and the hot water introduced into the heat exchanger via the forward pipe and heated is supplied to the hot water storage tank via the return pipe (boiling operation).

[0010] According to claim 1, the return pipe has a drain plug. D1 When the heat pump water heater is not to be used for a long period of time, for example, the user may turn off the drain valve. D1 By opening the drain and draining the water from the hot and cold water circulation circuit, damage caused by freezing in the hot and cold water circulation circuit, heat exchanger, and circulation pump due to low temperatures can be prevented. After that, when the non-use period ends and you want to resume using the heat pump water heater, D1 The water drain valve must be opened to allow water to flow again and remove the air from the hot water storage tank and the hot water circulation circuit. However, since there is a possibility that residual water from the above-mentioned water drainage may cause freezing in the heat exchanger, if the air removal is not completed, the user must open the water drain valve. D1 With the window open, a decompression instruction is given via the operating means.

[0011] Then, the control means receives the thawing instruction (thawing instruction receiving process), and the thawing operation is started (thawing operation starting process). That is, the refrigerant heated by the heating means based on the control of the control means is supplied to the heat exchanger. As a result, even if the heat exchanger has frozen, the frozen portion begins to melt due to the heat received from the heated refrigerant. As time passes, the melting progresses, and the drain plug in the heat exchanger D1 As a result of this water flow starting, even if the impeller inside the circulating pump has been locked due to the remaining water in the pump being frozen, water also gradually starts to flow near the impeller, resulting in the frozen area around the impeller gradually melting.

[0012] Here, if the circulation pump is driven continuously immediately after the start of the thawing operation, the frozen areas around the impeller described above may not melt sufficiently, causing the impeller to not rotate, which may result in overloading the circulation pump's drive motor. In order to avoid this, according to claim 1, the control means executes a standby process for waiting for a predetermined period of time after the start of the thawing operation by the thawing operation start process, and after the completion of this standby period, the circulation pump is driven (pump drive process). As a result, the circulation pump starts to be driven after the frozen parts around the impeller have sufficiently melted, so that it is possible to avoid overloading of the drive motor due to the non-rotation of the impeller.

[0013] In addition, since the circulation pump is driven to ensure that water flows through the hot and cold water circulation circuit, even if a thaw command is mistakenly issued when the water is not frozen, heat from the heated refrigerant is sequentially supplied to the water flowing through the heat exchanger, so that overheating does not occur inside the heat exchanger.

[0014] Furthermore, according to claim 2, the control means executes a process for stopping the thawing operation, so that the thawing operation started as described above can be smoothly terminated when a predetermined condition is satisfied.

[0015] In addition, according to claim 3, when the detected temperature in the return pipe becomes high to a certain extent and the rotation speed of the circulation pump also becomes high to a certain extent, it is possible to accurately detect that the frozen areas around the impeller have melted and sufficient water is circulating (= it is a state in which the thawing operation can be terminated).

[0016] Furthermore, according to claim 4, the operating means can be configured as a switch located in a position that can prevent inadvertent erroneous operation during normal use and that can be reliably operated when freezing is suspected. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of an entire configuration of a heat pump water heater according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a side view showing a schematic installation state of a heat pump unit and a tank unit. [Diagram 3] A functional block diagram showing the functional configuration of a heating control device [Figure 4] FIG. 2 is an exploded perspective view showing the internal structure of the heat pump unit. [Diagram 5] A diagram showing the operation of a heat pump water heater during boiling operation [Figure 6] FIG. 1 is a flowchart showing a control procedure executed by a defrosting operation control unit of a heating control device. [Figure 7] A graph showing the behavior over time of the electronic expansion valve, outdoor fan, compressor, and heating circulation pump after the start of defrosting operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, an embodiment of the present invention will be described with reference to the drawings.

[0019] <Outline configuration> 1 and 2, a heat pump 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. As shown in Fig. 2, this example shows a case where the heat pump water heater 100 is used in a cold region, and the heat pump unit 3 is installed on a stand 60 to increase the installation height so that it is not buried in snow.

[0020] As shown in FIG. 1, the heat pump unit 3 is configured as a so-called outdoor unit, and includes a water-refrigerant heat exchanger 15 (corresponding to a 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-refrigerant heat exchanger 15 has a refrigerant-side flow path 15b having a refrigerant inlet 15A and a refrigerant outlet 15B for circulating the refrigerant, and a water-side flow path 15a having a hot water inlet 15C and a hot water outlet 15D, 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 (corresponding to a forward pipe) that runs from the lower part of the hot water storage tank 2 to the water-refrigerant heat exchanger 15, and a heating return pipe 6 (corresponding to a return pipe) that runs from the water-refrigerant heat exchanger 15 back to the upper part of the hot water storage tank 2, and a heating circulation circuit 4 is formed as a hot water circulation circuit that spans the tank unit 1 and the heat pump unit 3.

[0021] The heating supply pipe 5 is connected to a lower part of the hot water storage tank 2, and the heating return pipe 6 is connected to an upper part 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 within the heating circulation circuit 4 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 circulation pump 19 is driven by a drive motor 19m.

[0022] At this time, the heating return pipe 6 is provided across the heat pump unit 3 and the tank unit 1, and is exposed to the outside of the heat pump unit 3 via a connection port C1, and is connected to the inside of the tank unit 1 via a connection port C2. A drain plug D1 is provided near the connection port C1 in the heat pump unit 3, and a drain plug D2 is provided near the connection port C2 in the tank unit 1. Note that a check valve B is provided on the heating return pipe 6 closer to the hot water storage tank 2 than the drain plug D2, which allows a flow from the water-refrigerant heat exchanger 15 to the hot water storage tank 2 and prevents a reverse flow from the hot water storage tank 2 to the water-refrigerant heat exchanger 15. Similarly, the heating supply pipe 5 is provided across the tank unit 1 and the heat pump unit 3, and is exposed to the outside of the tank unit 1 through a connection port C3, and is connected to the inside of the heat pump unit 3 through a connection port C4. A drain plug D3 is provided in the heat pump unit 3 near the connection port C4.

[0023] In addition, the heating supply pipe 5 is provided with an inlet water temperature sensor 23 which detects the inlet water temperature T1 of the hot water flowing into 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 hot water temperature detection means) which detects the boiling temperature Tb of the hot water flowing out from the water side flow path 15a toward the hot water storage tank 2.

[0024] In the tank unit 1, a plurality of hot water temperature sensors 12 for detecting the temperature Tw of the hot water in the hot water tank 2 are provided vertically on the side of the hot water tank 2. A water supply pipe 7 for supplying water to the hot water tank 2 is connected to the lower part of the hot water tank 2, and a hot water outlet pipe 8 for outletting the stored high temperature water is connected to the upper part of the hot water tank 2. The hot water outlet pipe 8 has a negative pressure intake function that opens to introduce air into the hot water tank 2 when the pressure inside the hot water tank 2 becomes negative, and is provided with a pressure relief valve 119 that opens to release pressure when the pressure inside the hot water tank 2 exceeds the valve opening pressure, and a water supply bypass pipe 9 is provided branching off from the water supply pipe 7. The pressure relief valve 119 is provided with a manual lever (not shown) for manually opening the valve.

[0025] Further provided are 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 a set hot water supply temperature, a hot water supply pipe 108a for supplying the hot water mixed by the mixing valve 10 to a hot water supply terminal 125, and a hot water supply temperature sensor 11 that detects the hot water supply temperature in the hot water supply pipe 108a. A check valve 117 is provided midway through the water supply pipe 7, which reduces the city water pressure to a certain water supply pressure (for example, a set pressure value of 380 kPa) and prevents the hot water in the hot water storage tank 2 from flowing back upstream.

[0026] 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 the hot water supply pipes 108a and 108b. A freeze-proof faucet 120 for stopping the water supply and draining the primary side faucet 121 and the hot water supply pipe 108b is buried underground below the freezing depth in the primary side faucet 121 of the check valve 117 outside the tank unit 1 and in the branch faucet 123 branching off from the hot water supply pipe 108b. The freeze-proof faucet 120 includes an operating handle 120a, a drain outlet 120b, and a hot water discharge outlet 120c.

[0027] The heat pump unit 3 also includes a compressor 14 that compresses the refrigerant, a four-way valve 31, 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 a heat source side heat exchanger that exchanges heat between the air as a heat source and the refrigerant, and an outdoor fan 67 that sends outside air to the air heat exchanger 17. The compressor 14, the four-way valve 31, 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 circular shape by refrigerant piping 18 to form a refrigerant circulation circuit 30.

[0028] The four-way valve 31 is a valve having four ports, and switches which of the two ports for the remaining pipe sections 18a, 18c is connected to each of the two ports for the pipe sections 18b, 18d (constituting the main refrigerant path) of the refrigerant pipe 18. The two ports for the pipe sections 18a, 18c are connected to each other by a secondary refrigerant path consisting of the pipe sections 18a, 18c arranged in a loop, and the compressor 14 is provided on this secondary refrigerant path. The compressor 14 is driven by a drive motor 14m.

[0029] For example, when the four-way valve 31 is switched to the state shown in FIG. 1, the piping section 18a on the discharge side of the compressor 14 is connected to the piping section 18b on the inlet side of the water-refrigerant heat exchanger 15, so that the air heat exchanger 17 functions as an evaporator that evaporates the low-temperature, low-pressure refrigerant from the electronic expansion valve 16, and the refrigerant in the refrigerant piping 18 is radiated in the water-refrigerant heat exchanger 15 to release heat and generate hot water in the heating circulation circuit 4. The generated hot water is supplied to the hot water storage tank 2 through the heating return pipe 6 by the flow of hot water in the heating circulation circuit 4 induced by the heating circulation pump 19, and the temperature of the hot water in the hot water storage tank 2 can be increased (=boiling operation). When the four-way valve 31 is switched to another state, the piping section 18a is connected to the piping section 18d on the air heat exchanger 17 side, so that the air heat exchanger 17 functions as a condenser, and the frost generated on the air heat exchanger 17 can be melted (=defrosting operation). The refrigerant circulation circuit 30 and the compressor 14, the four-way valve 31, the air heat exchanger 17, and the electronic expansion valve 16 connected thereto correspond to the heating means.

[0030] A heat pump cycle is formed by circulating, for example, an R32 refrigerant in the refrigerant circulation circuit 30. A discharge temperature sensor 20 for detecting a refrigerant discharge temperature Tout of the refrigerant discharged from the compressor 14 is provided in the refrigerant pipe 18 between the compressor 14 and the refrigerant-side flow path 15b of the water-refrigerant heat exchanger 15, and an outside air temperature sensor 22 for detecting an outside air temperature Tair is provided on the air inlet side of the air heat exchanger 17.

[0031] The tank unit 1 is provided with a hot water storage control device 40 to which the detection results of the sensors 11 and 12 are input. Similarly, the heat pump unit 3 is provided with a heating control device 50 (corresponding to a control means) to which the detection results of the sensors 20, 22, 23 and 24 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 control the operation of each device in the tank unit 1 and the heat pump unit 3 while cooperating with each other based on the detection results of the sensors 11, 12, 20, 22, 23 and 24, etc.

[0032] For example, the heating control device 50 controls the drive motor 19m of the heating circulation pump 19, the compressor 14, the four-way valve 31, the outdoor fan 67, the electronic expansion valve 16, etc., and drives the heating circulation pump 19 at a predetermined rotation speed while performing heating using the heat pump unit 3, thereby performing the boiling operation in which hot water is introduced into the water-refrigerant heat exchanger 15 via the heating forward pipe 5 and heated by heat exchange with the refrigerant, and is supplied to the hot water storage tank 2 via the heating return pipe 6.

[0033] Note that there may be a master-slave relationship in terms of control between the heating control device 50 and the hot water control device 40, where, for example, the hot water control device 40 outputs an operation command based on the detection results of the sensors 11 and 12 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 and the detection results of each sensor 20, 22, 23, and 24. In the following, this specification will be described taking such a case as an example.

[0034] <Heating control device> Next, a description will be given of the heating control device 50 provided in the heat pump unit 3. Although detailed illustration is omitted, the heating control device 50 includes a storage unit that stores various data and programs, and a control unit that performs calculation and control processing. The functional configuration of this heating control device 50 will be described with reference to FIG.

[0035] As shown in FIG. 3, the heating control device 50 functionally includes a four-way valve control unit 410A, a compressor control unit 410B, an expansion valve control unit 410C, an outdoor fan control unit 410D, a pump control unit 410F, and a defrosting operation control unit 410H.

[0036] The heat pump unit 3 of this embodiment performs various controls based on an operation command output from the hot water storage control device 40. That is, the operation command output by the hot water storage control device 40 is input to the four-way valve control unit 410A. In response to the operation command, the four-way valve control unit 410A determines whether the heat pump unit 3 actually causes the air heat exchanger 17 to function as an evaporator or a condenser. The four-way valve control unit 410A outputs an opening / closing signal corresponding to the operation mode represented by the operation command to the four-way valve 31, and switches the four-way valve 31.

[0037] Furthermore, the four-way valve control unit 410A outputs operation information corresponding to the determination result to the compressor control unit 410B, the expansion valve control unit 410C, the outdoor fan control unit 410D, the pump control unit 410F, and the defrosting operation control unit 410H. Note that this operation information includes the hot water temperature Tw 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.

[0038] 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, and the operation information corresponding to the operation command of the hot water storage control device 40 (these may be input directly or indirectly; the same applies below). In this example, the compressor control unit 410B sets a target rotation speed of the compressor 14 based on the input outside air temperature Tair and boiling temperature Tb, and controls the rotation speed of the drive motor 14m of the compressor 14 to increase or decrease so as to reach this target rotation speed.

[0039] 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.

[0040] 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. In this example, 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 to the target rotation speed.

[0041] The pump control unit 410F includes a target rotation speed setting unit 410Fa, a drive signal output unit 410Fb, and a rotation speed detection unit 410Fd. The boiling temperature Tb detected by the boiling temperature sensor 24, the outside air temperature Tair detected by the outside air temperature sensor 22, the inlet water temperature T1 detected by the inlet water temperature sensor 23, and the operation information corresponding to the operation command of the hot water storage control device 40 are input to the pump control unit 410F. The target rotation speed setting unit 410Fa sets a target rotation speed of the drive motor 19m of the heating circulation pump 19 based on these. The drive signal output unit 410Fb outputs a drive signal that increases or decreases the rotation speed of the drive motor 19m so as to reach the set target rotation speed. The rotation speed detection unit 410Fd detects the actual rotation speed N of the drive motor 19m of the heating circulation pump 19, and outputs the value to the defrosting operation control unit 410H described later.

[0042] The defrosting operation control unit 410H will be described later.

[0043] <Internal structure of heat pump unit> Next, the internal structure of the heat pump unit 3 will be described with reference to Fig. 4. As shown in Fig. 4, the heat pump unit 3 includes a housing 206 formed in a substantially hollow rectangular parallelepiped shape that forms the outer contour of the heat pump unit 3. The housing 206 includes an upper cover 206a consisting of a top plate 206a1, a front upper plate 206a2, and a rear upper plate 206a3, a front panel 206b in the front lower portion, and a right side plate 206c.

[0044] A vertical partition wall 221 is provided inside the housing 206, separating an air blowing chamber 219 in which the outdoor fan 67 is disposed and a machine room 220 in which the compressor 14 is disposed. A horizontal partition wall 222 is provided inside the housing 206, located above the air blowing chamber 219 and the machine room 220 and disposed so as to cross the air blowing chamber 219 and the machine room 220. A hot water circuit chamber 223 in which the water-refrigerant heat exchanger 15 is disposed is formed above the air blowing chamber 219 and the machine room 220 via the horizontal partition wall 222. As a result, inside the housing 206, the space above the horizontal partition wall 222 is partitioned as a hot water circuit chamber 223, and in the space below the horizontal partition wall 222, one side of the vertical partition wall 221 in the left-right direction (the left side in this example) is partitioned as an air blower chamber 219, and the other side of the vertical partition wall 221 in the left-right direction (the right side in this example) is partitioned as a machine chamber 220.

[0045] The hot water circuit chamber 223 is provided with a mounting base (not shown) for mounting the water-refrigerant heat exchanger 15, and the mounting base is fixed on the horizontal partition wall 222. As a result, the water-refrigerant heat exchanger 15 is disposed with a predetermined gap (not shown) between the horizontal partition wall 222 and the water-refrigerant heat exchanger 15. In the gap S formed between the horizontal partition wall 222 and the water-refrigerant heat exchanger 15, the refrigerant pipe 18 connected to the refrigerant inlet 15A or the refrigerant outlet 15B, the heating forward pipe 5, and the heating return pipe 6 are disposed (not shown in detail). In this example, the water-refrigerant heat exchanger 15 is disposed on the blower chamber 219 side in the left-right direction of the hot water circuit chamber 223. That is, the water-refrigerant heat exchanger 15 is disposed in the hot water circuit chamber 223 at a position corresponding to the upper part of the blower chamber 219. The heating circulation pump 19 is disposed on the right side of the water-refrigerant heat exchanger 15 in the hot water circuit chamber 223 (above the horizontal partition wall 222).

[0046] In the machine room 220, the compressor 14, the four-way valve 31, the electronic expansion valve 16, etc., which are connected by refrigerant piping 18, are arranged.

[0047] <Configuration near the right side panel> The right side plate 206c provided to cover the right side of the machine chamber 220 includes an upper opening 211 and a lower opening 212. A terminal block mounting bracket 213 for mounting a terminal block (not shown) to which a signal line and a power line (not shown) are connected is attached from the inside (left side) of the right side plate 206c at a position corresponding to the upper opening 211 of the right side plate 206c. At this time, the terminal block mounting bracket 213 is attached to the right side plate 206c in such a manner that its outer end (right end) is exposed outward from the upper opening 211, and the exposed outer end (right end) is covered by a terminal block cover 214 attached to close the upper opening 211 from the right side. The terminal block mounting bracket 213 is provided with an operation switch (not shown) for starting a thawing operation described later, and the operation switch can be manually operated from the outside through an operation window 214a provided in the terminal block cover 214 by removing a piping cover 225 described later.

[0048] On the other hand, the portion of the heating forward pipe 5 in the heat pump unit 3 on the side of the connection port C4 is inserted into a side panel 215 having a substantially flat plate shape arranged in a substantially vertical direction, and the connection port C4 is provided at the end of the insertion. Similarly, the portion of the heating return pipe 6 in the heat pump unit 3 on the side of the connection port C1 is also inserted into the side panel 215, and the connection port C1 is provided at the end of the insertion. The side panel 215 to which the heating forward pipe 5, the connection port C4, the heating return pipe 6, and the connection port C1 are attached in this manner is attached to the right side plate 206c in a manner in which it is arranged to protrude outward (to the right) from the lower opening 212. As a result, the piping cover 225 described later is removed to expose the side panel 215, and the drain plug D1 located near the connection port C1 and the drain plug D3 located near the connection port C4 can be manually operated from the outside.

[0049] As described above, the terminal block mounting bracket 213 and the terminal block cover 214 are attached near the upper opening 211, and the side panel 215 is attached near the lower opening 212. The outer side (right side) of the right side plate 206c is covered by a removable piping cover 225.

[0050] <Boiling operation> The boiling operation performed in the above-described configuration will be described with reference to Fig. 5. That is, when the boiling operation is performed, the four-way valve control unit 410A switches the four-way valve 31 so that the air heat exchanger 17 functions as an evaporator, and the compressor control unit 410B controls the drive of the drive motor 14m of the compressor 14 to reach a target rotation speed. In addition, the expansion valve control unit 410C controls the opening of the electronic expansion valve 16 so that the refrigerant discharge temperature Tout reaches a desired target temperature for control, and the outdoor fan control unit 410D controls the drive of the outdoor fan 67 to reach a target rotation speed.

[0051] Furthermore, the target rotation speed of heating circulation pump 19 is set to a normal rotation speed by target rotation speed setting unit 410Fa of pump control unit 410F. Then, a drive signal for executing rotation at the target rotation speed set by target rotation speed setting unit 410Fa is generated by drive signal output unit 410Fb and output to drive motor 19m of heating circulation pump 19.

[0052] 5, in the heating circulation circuit 4, hot water passes through the water-refrigerant heat exchanger 15 → heating return pipe 6 → hot water storage tank 2 → heating forward pipe 5 → water-refrigerant heat exchanger 15 →..., and hot water is circulated in the heating circulation circuit 4. Meanwhile, in the refrigerant circulation circuit 30, the refrigerant passes through the water-refrigerant heat exchanger 15 → electronic expansion valve 16 → air heat exchanger 17 → compressor 14 → water-refrigerant heat exchanger 15 →..., and refrigerant is circulated in the refrigerant circulation circuit 30. As a result, in the water-refrigerant heat exchanger 15, the refrigerant in the flow path 15b releases heat to the hot water in the flow path 15a to generate hot water, and the generated hot water is supplied to the hot water storage tank 2, and the temperature of the hot water in the hot water storage tank 2 increases.

[0053] <Background and Features of the Embodiment> In this embodiment, the drain plug D1 is provided on the heating return pipe 6, and the drain plug D3 is also provided on the heating supply pipe 5. When the user will not be using the heat pump water heater 100 for a long period of time, for example, the user can operate the antifreeze valve 120 to stop the water supply and open the drain plugs D1 and D3 to drain the water from the heating circulation circuit 4, the water-refrigerant heat exchanger 15, the heating circulation pump 19, and the hot water storage tank 2, thereby preventing damage caused by freezing in the heating circulation circuit 4, the water-refrigerant heat exchanger 15, the heating circulation pump 19, and the hot water storage tank 2 due to low temperatures.

[0054] Thereafter, when the period of non-use ends and the user resumes use of the heat pump water heater 100, the antifreeze tap 120 is operated to resume water supply to the heat pump water heater 100, and water is passed through the hot water storage tank 2 again to remove air from within the hot water storage tank 2. Once the air has been bled from the hot water tank 2, the drain plug D1 or D2 is opened to allow water to flow again through the heating supply pipe 5, the heating circulation pump 19, the water-refrigerant heat exchanger 15, and the heating return pipe 6 up to the drain plug D1 or D2, thereby bleed-off the air from these heating circulation circuits 4. At this time, water is prevented from passing through the route from the top of the hot water tank 2 to the drain plugs D1, D2 by the action of the check valve B. Note that instead of the check valve B, a manual on-off valve may be provided on the heating return pipe 6 between the drain plugs D1, D2 and the top of the hot water tank 2, and the on-off valve may be manually closed when bleed-off the air from the heating circulation circuit 4. Then, when it is confirmed that water has flowed out from the drain valve D1 or D2, it is determined that air bleeding from the heating circulation circuit 4 is complete, and the drain valves D1, D2 are closed and the use of the heat pump water heater 100 is resumed.

[0055] However, even if the water is drained as described above, the small amount of remaining water that is not completely drained from the water-refrigerant heat exchanger 15 or the heating circulation pump 19 may freeze. If the flow path is blocked due to the freezing of the remaining water in the water-refrigerant heat exchanger 15, water cannot flow out from the water drain plugs D1 and D2. In addition, if the remaining water at the bottom of the heating circulation pump 19 or the remaining water on the shaft of the impeller freezes, the impeller may lock. If water does not come out from the open water drain plugs D1 and D2 even after waiting for a predetermined time and air bleeding cannot be completed, the user recognizes that freezing has occurred in the water-refrigerant heat exchanger 15 and executes a predetermined thawing operation. The feature of this embodiment is the control mode of the heating control device 50 when the thawing operation is executed. For this purpose, as shown in FIG. 3, the heating control device 50 is provided with a thawing operation control unit 410H, which controls the corresponding parts. The details will be described below with reference to FIG. 6 and FIG. 7.

[0056] Fig. 6 is a flow chart showing a control procedure executed by the defrosting operation control unit 410H of the heating control device 50 when the defrosting operation is performed. Figs. 7(a) to (d) are graphs showing the behavior over time of the electronic expansion valve 16, the outdoor fan 67, the compressor 14, and the heating circulation pump 19 after the start of the defrosting operation.

[0057] As a preparation procedure, the user first operates the antifreeze water tap 120 to resume water supply to the heat pump water heater 100, and operates the manual lever of the pressure relief valve 119 to open the pressure relief valve 119, and re-passes water through the hot water storage tank 2 to bleed air from the hot water storage tank 2. At this time, the heating circulation circuit 4 has a larger pressure loss than the hot water storage tank 2, so water does not pass through even if the drain valves D1 and D2 are open. When it is confirmed that the air in the hot water storage tank 2 has been released and water has flowed out from the pressure relief valve 119, the user operates the manual lever of the pressure relief valve 119 to close the pressure relief valve 119, assuming that the air bleed from the hot water storage tank 2 has been completed. Next, the user opens the drain valves D1 and D2 to bleed air from the heating circulation circuit 4. In this state, first in S5 in FIG. 6, the power supply, which was in the OFF state at this time due to the non-use, is turned ON in response to an appropriate operation by the user.

[0058] Thereafter, as described above, when the piping cover 225 of the housing 206 of the heat pump unit 3 is removed and the operation switch (corresponding to the operation means) of the terminal block mounting bracket 213 is operated by the user, the operation is accepted in S10. Note that the operation of the operation switch corresponds to a defrosting instruction, and the process executed by the defrosting operation control unit 410H in S10 corresponds to a defrosting instruction acceptance process. Instead of the operation switch, an appropriate operation means such as a remote control provided on the tank unit 1 side may be used. In this case, an operation signal corresponding to the user's operation of the remote control or the like is acquired by the defrosting operation control unit 410H of the heating control device 50 directly or via the hot water storage control device 40, and the operation is accepted in S10. When the operation in S10 is accepted, if it is determined that there is no risk of freezing based on the detection result of the outside air temperature Tair (for example, in summer), the acceptance of the defrosting operation may be canceled to suppress the execution of unnecessary defrosting operations.

[0059] Thereafter, in S15, an LED (not shown: preferably provided near the operation switch) that indicates the execution of the defrosting operation and that is provided in the housing 206 or an appropriate location inside it starts blinking. Then, in S20, in the refrigerant circulation circuit 30 of the heat pump unit 3, the heat pump is started in the same manner as in the boiling operation, and the defrosting operation is started (see time t0 in FIGS. 7(a) to (d)). The process executed by the defrosting operation control unit 410H in S20 corresponds to the defrosting operation start process.

[0060] That is, by outputting an operation command to the four-way valve control unit 410A, the four-way valve 31 is switched so that the air heat exchanger 17 functions as an evaporator. Also, by outputting an operation command to the compressor control unit 410B, the compressor 14 is driven and controlled so as to have a predetermined target rotation speed in the defrosting operation (see FIG. 7(c)). Also, by outputting an operation command to the expansion valve control unit 410C, the opening degree of the electronic expansion valve 16 is controlled so that the refrigerant discharge temperature Tout becomes a predetermined target temperature in the defrosting operation (see FIG. 7(a)). Furthermore, by outputting an operation command to the outdoor fan control unit 410D, the outdoor fan 67 is driven and controlled so as to have a predetermined target rotation speed in the defrosting operation (see FIG. 7(b)).

[0061] As a result, in the same manner as in the boiling operation, the refrigerant circulates in the refrigerant circulation circuit 30 in the order of water-refrigerant heat exchanger 15 → electronic expansion valve 16 → air heat exchanger 17 → compressor 14 → water-refrigerant heat exchanger 15 → · ·, and as a result, heat is released from the refrigerant in the flow path 15b in the water-refrigerant heat exchanger 15. As a result, even if freezing has occurred in the water-refrigerant heat exchanger 15, the frozen portion begins to melt by receiving heat from the refrigerant heated in the refrigerant circulation circuit 30.

[0062] Then, as the melting progresses over time, water gradually starts to flow toward the heating return pipe 6 toward the drain plugs D1, D2 in the water-refrigerant heat exchanger 15. With this start of water flow, even if the impeller in the pump has been locked due to the freezing of residual water in the heating circulation pump 19, water also gradually starts to flow near the impeller, resulting in the frozen area around the impeller gradually melting. Here, if heating circulation pump 19 is started immediately after the heat pump is started in S20, the frozen areas around the impeller described above may not melt sufficiently, causing the impeller to not rotate, which may result in overloading drive motor 19m of heating circulation pump 19.

[0063] In order to avoid this, in this embodiment, after the heat pump is started in S20, it is determined in S25 whether or not the system has waited for a predetermined waiting period (e.g., 2 minutes, which corresponds to the predetermined period). Until the waiting period has elapsed, the result is No and the system waits in a loop (corresponding to a waiting process), and once the waiting period has elapsed, the result is Yes and the system proceeds to S30.

[0064] In S30, heating circulation pump 19 is started by outputting an operation command to pump control unit 410F, and the target rotation speed is controlled to be a predetermined target rotation speed in the thawing operation (see time t1 in FIG. 7(d)). The process executed by thawing operation control unit 410H in S30 corresponds to the pump drive process. In this way, heating circulation pump 19 is driven after the predetermined period of standby is completed, and as a result, heating circulation pump 19 starts to be driven after the frozen portion around the impeller has sufficiently melted, so that it is possible to avoid overloading of drive motor 19m due to non-rotation of the impeller.

[0065] Then, the process proceeds to S35, where it is determined whether the boiling temperature Tb detected by the boiling temperature sensor 24 is equal to or higher than a predetermined temperature (corresponding to a first threshold value, 3°C in this example; the same applies below) and whether the actual rotation speed N input from the rotation speed detection unit 410Fd of the pump control unit 410F is equal to or higher than a predetermined rotation speed (corresponding to a second threshold value, 500 rpm in this example; the same applies below). If Tb≧3°C and N≧500 rpm (=corresponding to a predetermined condition), the result is Yes, it is determined that the frozen residual water is in a melted state, and the process proceeds to S50 described below. If Tb<3°C or N<500 rpm, the result is No, and the process proceeds to S40. It should be noted that the above-mentioned determination conditions may be supplemented with a condition of Tb>T1 to improve the accuracy of the melting state determination.

[0066] In S40, after execution of S30, it is determined whether a predetermined timeout period (30 minutes in this example; the same applies below) has elapsed. If 30 minutes have elapsed, the result is Yes, and the process proceeds to S50, which will be described later. If 30 minutes have not elapsed, the result is No, and the process proceeds to S45.

[0067] In S45, it is determined whether or not a forced termination operation has been performed by the user via an appropriate termination operation means (not shown) that has been prepared in advance for forced termination. If a forced termination operation has been performed, the result is Yes, and the process proceeds to S50, which will be described later. If a forced termination operation has not been performed, the process returns to S35, and the same procedure is repeated.

[0068] In S50, the heat pump that has been started in S20 is stopped, and the defrosting operation is ended (see time t2 in Figs. 7(a) to 7(c)). That is, the compressor 14 and the outdoor fan 67 are stopped and the electronic expansion valve 16 is set to a predetermined stop opening degree by outputting operation commands to the compressor control unit 410B, the outdoor fan control unit 410D, and the expansion valve control unit 410C. Note that the process executed by the defrosting operation control unit 410H in S50 corresponds to the defrosting operation stop process. Then, immediately thereafter, in S55, the heating circulation pump 19 that has been started in S30 is stopped (see time t2 in Fig. 7(d)).

[0069] Then, in S60, the LED that has been blinking since S15 is turned off, and this flow ends. The user closes the drain valves D1 and D2 that were opened as described above. This allows the device to return to a state in which normal operations such as the boiling operation can be performed.

[0070] <Effects of the embodiment> As described above, in this embodiment, when the user resumes use of the heat pump water heater 100 after the end of the non-use period, the drain plugs D1 and D2 are opened to allow water to flow again and bleed air from the hot water storage tank 2 and the heating circulation circuit 4. If air bleed cannot be completed, the user executes a thawing command via the operation switch with the drain plug D1 (or alternatively, D2) left open to start a thawing operation, and the refrigerant heated by the heating of the refrigerant circulation circuit 30 is supplied to the water-refrigerant heat exchanger 15 (S20). As a result, even if freezing has occurred in the water-refrigerant heat exchanger 15 during the non-use period, the frozen portion can be melted by receiving heat from the heated refrigerant.

[0071] At this time, after the start of the thawing operation in S20, and after the completion of a predetermined period (2 minutes in the above example) (S25), the heating circulation pump 19 is driven (S30). As a result, the melting progresses, water starts to flow toward the drain plugs D1 and D2 in the water-refrigerant heat exchanger 15, and the driving of the heating circulation pump 19 starts after the melting of the frozen parts around the impeller has progressed sufficiently, so that it is possible to avoid an overload of the driving motor caused by the non-rotation of the impeller, which occurs when the heating circulation pump 19 is driven continuously immediately after the start of the thawing operation. In addition, since the driving of the heating circulation pump 19 ensures that water flows through the heating circulation circuit 4, even if a thawing command is mistakenly issued using the operation switch when the water is not frozen, heat from the heated refrigerant is sequentially supplied to the water flowing through the water-refrigerant heat exchanger 15. Therefore, excessive temperature rise does not occur within the water-refrigerant heat exchanger 15.

[0072] Furthermore, in particular in this embodiment, the defrosting operation started in S20 as described above can be smoothly terminated (S50) when a predetermined condition (Tb≧3°C and N≧500 rpm in the above example) is satisfied.

[0073] In particular, in this embodiment, the predetermined conditions are Tb≧3° C. and N≧500 rpm. This makes it possible to accurately detect that the detected temperature in the heating return pipe 6 has increased to a certain degree, and the rotation speed of the heating circulation pump 19 has also increased to a certain degree, so that the frozen portion around the impeller has melted and sufficient water is circulating (= it is a state in which the thawing operation may be terminated).

[0074] In particular, in this embodiment, the operation switch is a switch provided in the heat pump unit 3 including the refrigerant circulation circuit 30 equipped with the compressor 14. This allows the operation switch to be configured as a switch located at a position that can prevent inadvertent erroneous operation during normal use and that can be reliably operated when freezing is suspected.

[0075] The present invention is not limited to the above-mentioned aspects, and can be applied within the scope of the present invention.

[0076] For example, the heat pump cycle 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 having 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 heat is exchanged 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 and the refrigerant exchange heat in the heat source side heat exchanger. In addition, a heat source side heat exchanger may be provided underground or in a relatively large-capacity water source, and the heat source side heat exchanger may exchange heat between the refrigerant and the underground or water source. Furthermore, a composite heat source type may be configured with a heat pump circuit using heat from the underground or water source and another heat pump circuit using air heat. Furthermore, in place of the liquid, the outside air, or the water source, other materials (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, and 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 4 Heating circulation circuit (hot water circulation circuit) 5. Heating supply pipe (supply pipe) 6 Heating return pipe (return pipe) 12 Hot water temperature sensor 14 Compressor (heating means) 15 Water refrigerant heat exchanger (heat exchanger) 16 Electronic expansion valve (heating means) 17 Air heat exchanger (heating means) 19 Heating circulation pump (circulation pump) 22 Outside air temperature sensor 23 Inlet water temperature sensor 24 Boiling temperature sensor (hot water temperature detection means) 30 Refrigerant circulation circuit (heating means) 31 Four-way valve (heating means) 40 Hot water storage control device 50 Heating control device (control means) 100 Heat pump water heater 410F Pump Control Unit T1 Inlet water temperature Tair Outside temperature Tb boiling temperature Tout Refrigerant discharge temperature

Claims

1. A hot water storage tank for storing hot water; A heat pump type heating means for heating a refrigerant; a heat exchanger for exchanging heat between the refrigerant heated by the heating means and the hot water in the hot water storage tank; A hot water circulation circuit including a forward pipe from the lower part of the hot water storage tank toward the heat exchanger and a return pipe from the heat exchanger back to the upper part of the hot water storage tank; A circulation pump that circulates the hot and cold water in the hot and cold water circulation circuit; A drain plug D1 is provided in the return pipe downstream and below the heat exchanger and the circulation pump, and in an open state allows air to be bled from inside the pipe; a control means for controlling the heating means and the circulating pump, and driving the circulating pump while heating with the heating means, thereby executing a boiling operation in which the hot water introduced into the heat exchanger through the supply pipe and heated by heat exchange with the refrigerant is supplied to the hot water storage tank through the return pipe; In a heat pump water heater having The water drain valve D1 does not flow out of the open state even when water is refilled to bleed air from the hot water storage tank and the hot water circulation circuit, and an operation means is provided that allows a user to execute a thawing instruction when freezing occurs in the heat exchanger, The control means a decompression instruction receiving process for receiving the decompression instruction via the operation means; a defrosting operation start process for starting a defrosting operation in which, when the defrosting instruction is received by the defrosting instruction receiving process, the heating means is controlled to supply heated refrigerant to the heat exchanger; a standby process of waiting for a predetermined period of time after the start of the defrosting operation by the defrosting operation start process; a pump drive process of driving the circulation pump after waiting for the predetermined period of time in the standby process; A heat pump water heater characterized by carrying out the above.

2. The control means further comprises: When a predetermined condition is satisfied, the heating means is controlled, and a thawing operation stop process is executed to end the thawing operation started by the thawing operation start process.

2. The heat pump water heater according to claim 1.

3. The predetermined condition is:

3. The heat pump type water heater according to claim 2, wherein the temperature detected by the hot and cold water temperature detection means provided in the return pipe is equal to or higher than a predetermined first threshold value, and the rotation speed of the circulation pump is equal to or higher than a predetermined second threshold value.

4. The operation means includes: A switch provided on an outdoor unit that includes the heating means. The heat pump water heater according to any one of claims 1 to 3.

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