JP2020003093A - Heat pump water heater - Google Patents

Abstract

To provide a heat pump water heater capable of promptly determining failure of a defrosting valve.SOLUTION: A heat pump water heater includes: a heat pump type heat source machine configured by connecting a compressor, a condensation heat exchanger, expansion means and an evaporation heat exchanger by a refrigerant circuit; a hot water storage tank; and control means for controlling a hot water storage operation for storing hot water heated by the heat pump type heat source machine in the hot water storage tank. The refrigerant circuit includes: a bypass passage bypassing the expansion means; and a defrosting valve for opening/closing the bypass passage. When frost formation on the evaporation heat exchanger is detected, the control means opens the defrosting valve and closes the expansion means so as to perform a defrosting operation. The heat pump water heater further includes failure determination means for making a failure determination of the defrosting valve on the basis of a change of an electric current value or electric power consumption of the compressor when the control means performs opening control of the defrosting valve.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat pump water heater, and more particularly to a heat pump water heater that performs a defrosting operation using a defrost valve provided in a bypass passage that bypasses an expansion valve.

  BACKGROUND ART Conventionally, a heat pump hot water supply device that performs a hot water storage operation of storing hot water heated by a heat pump heat source device in a hot water storage tank and uses the stored hot water for hot water supply has been widely used. The heat pump type heat source device is configured by connecting a compressor, a condensation heat exchanger, expansion means, and an evaporation heat exchanger by a refrigerant circuit.

  In the hot water storage operation, the refrigerant absorbs heat from the outside air in the evaporative heat exchanger of the heat pump heat source device, and the heat of the refrigerant is used for heating hot water. Therefore, particularly when the outside air temperature is low, moisture contained in the outside air whose temperature has been lowered due to heat absorption is easily condensed and frost is easily formed on the evaporative heat exchanger. Since the frost formation of the evaporative heat exchanger prevents heat absorption from the outside air, if the frost formation proceeds to some extent during the hot water storage operation, a defrosting operation for removing the frost formation is performed.

  The defrosting operation is performed by flowing a high-temperature refrigerant through the evaporative heat exchanger. For this defrosting operation, the refrigerant circuit is provided with a bypass passage for bypassing the expansion means and a defrost valve for opening and closing this bypass passage. The defrost valve is closed during the hot water storage operation and is opened during the defrost operation, so that if the defrost valve fails, the defrost operation and the hot water storage operation cannot be performed.

  For example, if a failure in closing the defrost valve occurs due to, for example, biting of a foreign object, a high-temperature refrigerant is continuously supplied to the compressor, and the heat pump heat source device may be broken. Therefore, for example, as in Patent Literature 1, a technique is known in which a compressor is stopped when a temperature switch on the outlet side of an evaporative heat exchanger detects an abnormally high temperature of a refrigerant.

  Further, when an opening failure occurs due to sticking to the defrost valve or the like, even if the defrost operation is started, high-temperature refrigerant is not supplied to the evaporative heat exchanger and defrost cannot be performed. Therefore, for example, as disclosed in Patent Document 2, there is known a technique for detecting a defective opening of the defrost valve based on a change in the temperature of the refrigerant before and after the start of the defrost operation detected by a temperature sensor on the inlet side of the evaporative heat exchanger. Have been.

JP-A-63-162272 JP 2015-1350 A

  The heat pump type heat source unit is provided with an outside air temperature sensor, an incoming water temperature sensor, and an outgoing water temperature sensor for detecting the temperature of incoming and outgoing hot and cold water. The refrigerant circuit is provided with an inlet-side temperature sensor and an outlet-side temperature sensor of the evaporative heat exchanger for detecting the temperature of the refrigerant, and a discharge-side temperature sensor of the compressor. Therefore, it has been considered to eliminate the temperature sensor on the inlet side of the evaporative heat exchanger.

  In this case, it is possible to detect a change in the temperature of the refrigerant as in Patent Literature 2 using an outlet-side temperature sensor of the evaporative heat exchanger as in Patent Literature 1. However, since the gas passes through the frosted evaporative heat exchanger, the distance from the defrost valve to the outlet-side temperature sensor becomes longer, and the time from when the defrosting operation is started to when a temperature change is detected becomes longer, and the temperature increases. There is a problem that the change becomes small and the detection becomes difficult. An object of the present invention is to provide a heat pump water heater that can quickly determine a failure of a defrost valve.

  The invention according to claim 1 is a heat pump type heat source device configured by connecting a compressor, a condensation heat exchanger, expansion means, and an evaporative heat exchanger by a refrigerant circuit, a hot water storage tank, and heating by the heat pump type heat source device. Control means for controlling a hot water storage operation for storing the supplied hot and cold water in the hot water storage tank; a bypass passage for bypassing the expansion means in the refrigerant circuit; and a defrost valve for opening and closing the bypass passage. In a heat pump water heater in which when the frost formation of the exchanger is detected, the control means opens the defrost valve and closes the expansion means to perform a defrost operation, wherein the control means controls the opening of the defrost valve. In this case, there is provided a failure determining means for performing a failure determination of the defrost valve based on a change in a current value or a power consumption value of the compressor.

  According to the above configuration, the heat pump hot water supply device performs a defrosting operation when frost formation on the evaporative heat exchanger is detected during the hot water storage operation. If the high-temperature refrigerant discharged from the compressor flows through the bypass passage when the defrosting operation is started and the defrost valve is controlled to open, the pressure on the discharge side of the compressor immediately decreases, and the load on the compressor decreases. , The current value or the power consumption value of the compressor decreases. On the other hand, if the bypass passage is closed due to the failure of the defrost valve when the defrost valve is opened, the pressure on the discharge side of the compressor does not change, and the load on the compressor does not change. The current value or the power consumption value does not change. Therefore, the failure determination means can quickly determine the failure of the defrost valve based on a change in the current value or the power consumption value of the compressor after the defrost valve is opened.

  According to a second aspect of the present invention, in the first aspect of the present invention, the refrigerant circuit further includes a temperature detection unit for detecting a refrigerant temperature during the defrosting operation, and the failure determination unit determines that the failure of the defrost valve is normal. After the determination, when the control unit controls the closing of the expansion unit, the failure determination unit performs a failure determination of the expansion unit based on a change in refrigerant temperature detected by the temperature detection unit. I have.

  According to the above configuration, the expansion means is controlled to close after the defrost valve is normally opened. Therefore, even when the bypass passage is closed, the discharge side of the compressor is not closed, and an excessive load is not applied to the compressor, so that failure of the compressor can be prevented. Further, when the expansion means is closed, the low-temperature refrigerant does not flow, so that the temperature detection means detects a large change in the refrigerant temperature. On the other hand, if the expansion means is not closed due to a failure, the low-temperature refrigerant flows while being mixed with the high-temperature refrigerant, so that the defrosting ability decreases and the change in the refrigerant temperature detected by the temperature detection means decreases. Therefore, the failure determination unit can determine the failure of the expansion unit based on the change in the refrigerant temperature detected by the temperature detection unit.

  According to a third aspect of the present invention, in the second aspect, the temperature detecting means is disposed on a refrigerant outlet side of the evaporative heat exchanger or on a discharge side of the compressor.

  According to the above configuration, the failure determination unit can perform the failure determination of the expansion unit using the existing temperature detection unit.

  ADVANTAGE OF THE INVENTION According to the heat pump hot-water supply apparatus of this invention, failure of a defrost valve can be determined quickly. Further, it is possible to determine the failure of the expansion means.

It is a figure showing composition of a heat pump hot water supply device concerning an example of the present invention. It is a flowchart which shows a failure determination control.

  Hereinafter, embodiments for carrying out the present invention will be described based on examples.

First, the overall configuration of the heat pump water heater 1 of the present invention will be described.
As shown in FIG. 1, a heat pump hot water supply device 1 controls a hot water storage / hot water supply unit 2 having a hot water storage tank 5 for storing hot water, a heat pump type heat source device 3 for heating the hot water in the hot water storage tank 5, and the heat pump hot water supply device 1. The control means 4 includes circulation pipes 8a and 8b for circulating hot water between the hot water supply unit 2 and the heat pump type heat source unit 3.

  The hot water supply unit 2 includes a hot water storage tank 5 having a vertically long cylindrical outer peripheral surface, a water supply pipe 6, a hot water supply pipe 7, a circulation pipe 8a, 8b, a circulation pump 11, an on-off valve 12, a mixing valve 13, a main control unit 16, An outer case 17 and the like are provided. The hot water storage tank 5 stores high-temperature hot water heated by the heat pump type heat source device 3.

  A water supply pipe 6 and a circulation pipe 8 a are connected to a lower end of the hot water storage tank 5. The water supply pipe 6 is provided with an on-off valve 12 for supplying low-temperature water to the hot water storage tank 5. A circulation pipe 8b and a hot water supply pipe 7 are connected to the upper end of the hot water storage tank 5, and the high-temperature hot water returned from the circulation pipe 8b is stored in the hot water storage tank 5. Hot water can be supplied to the tapping pipe 7.

  In the hot water storage tank 5, a plurality of temperature sensors 5a to 5d are arranged at predetermined intervals in the height direction, and the temperature detection signals of the temperature sensors 5a to 5d are transmitted to the main control unit 16. The outer case 17 is formed in a box shape made of a thin steel plate, and includes a hot water storage tank 5, a water supply pipe 6, a hot water supply pipe 7, most of the circulation pipes 8a and 8b, a circulation pump 11, an on-off valve 12, a mixing valve 13, and various types. Temperature sensors 15a to 15d, a main control unit 16, and the like.

Next, the heat pump type heat source device 3 will be described.
The heat pump type heat source unit 3 is configured by connecting a compressor 21, a condensation heat exchanger 22, an expansion valve 23 (expansion means), and an evaporation heat exchanger 24 by a refrigerant circuit 25 in which a refrigerant is sealed. The heat pump type heat source unit 3 includes a blower fan 27 for sending outside air to the evaporative heat exchanger 24, a bypass passage 31 for defrosting operation for removing frost from the evaporative heat exchanger 24, and a defrost valve including an electromagnetic valve. 32, an auxiliary control unit 33 connected to the main control unit 16 and controlling the heat pump type heat source unit 3, and an outer case 35 for accommodating them.

  The compressor 21 supplies the condensing heat exchanger 22 with the high-temperature and high-pressure refrigerant that has been adiabatically compressed and raised in temperature. The condensing heat exchanger 22 is constituted by a double pipe having a heat exchanger passage 22a provided between the circulation pipes 8a and 8b and an internal passage 22b which is a part of the refrigerant circuit 25. In the condensing heat exchanger 22, heat is exchanged between high-temperature and high-pressure refrigerant flowing through the internal passage 22b and hot water supplied from the circulation pipe 8a to the heat exchanger passage 22a to heat the hot water. I do.

  The expansion valve 23 is a control valve whose throttle amount is variable by driving an electric motor, and rapidly expands a high-pressure refrigerant whose temperature has been lowered by heat exchange to lower the refrigerant temperature to a temperature lower than the outside air temperature. The evaporating heat exchanger 24 has an internal passage 24a that is a part of the refrigerant circuit 25, and the internal passage 24a is configured by a heat transfer tube on which a plurality of fins are mounted. In the evaporative heat exchanger 24, by exchanging heat between the partially liquefied refrigerant flowing through the internal passage 24a and the outside air, the refrigerant absorbs heat from the outside air, rises in temperature, and is vaporized.

  In the hot water storage operation, the hot water is heated using the refrigerant sealed in the refrigerant circuit 25 in the heat pump type heat source device 3 and stored in the hot water storage tank 5. The high-temperature and high-pressure refrigerant discharged from the compressor 21 is supplied to the condensing heat exchanger 22 to be cooled by heat exchange with hot and cold water, sent to the expansion valve 23 and rapidly expanded to a temperature lower than the outside air temperature, and evaporated. The heat is sent to the heat exchanger 24, absorbs heat from the outside air, and returns to the compressor 21. In the condensation heat exchanger 22, the low-temperature hot water supplied from the lower end of the hot water storage tank 5 through the circulation pipe 8a is heated by the driving of the circulation pump 11, and the heated hot water is stored through the circulation pipe 8b. Hot water is stored from above the tank 5.

  The refrigerant circuit 25 includes a refrigerant passage 25a connecting the discharge side of the compressor 21 and the inlet side of the condensing heat exchanger 22, a refrigerant passage 25b connecting the outlet side of the condensing heat exchanger 22 and the inlet side of the expansion valve 23, and expansion. A refrigerant passage 25c connects the outlet side of the valve 23 and the inlet side of the evaporative heat exchanger 24, and a refrigerant passage 25d connects the outlet side of the evaporative heat exchanger 24 and the inlet side of the compressor 21.

  A discharge temperature sensor 28 for detecting the temperature of the refrigerant discharged from the compressor 21 is provided in the refrigerant passage 25a, and an outlet for detecting the temperature of the refrigerant supplied from the refrigerant outlet of the evaporative heat exchanger 24 is provided in the refrigerant passage 25d. A temperature sensor 29 is provided. The discharge temperature sensor 28 or the outlet temperature sensor 29 is a temperature detecting means for detecting the refrigerant temperature in the defrosting operation.

  In the refrigerant circuit 25, a bypass passage 31 branched from the refrigerant passage 25a and connected to the refrigerant passage 25c is provided in order to bypass the condensation heat exchanger 22 and the expansion valve 23. The bypass passage 31 is provided with a defrost valve 32 that is opened and closed by the auxiliary control unit 33 during the defrost operation.

  The frost formation on the evaporative heat exchanger 24 is caused, for example, when the outside air temperature detected by the outside air temperature sensor 30 is equal to or lower than a predetermined outside air temperature (for example, 5 ° C.). It is detected when the temperature exceeds a predetermined reference value (for example, 10 ° C.). When detecting the frost formation on the evaporative heat exchanger 24, the control means 4 opens the defrost valve 32 to perform the defrost operation. By opening the defrost valve 32, the high-temperature refrigerant discharged from the compressor 21 flows through the bypass passage 31 and is supplied to the evaporative heat exchanger 24.

Next, the control means 4 will be described.
The control means 4 includes a main control unit 16 provided in the hot water supply unit 2 and an auxiliary control unit 33 provided in the heat pump type heat source unit 3. Various operations are controlled based on detection signals from sensors and the like. That is, the control means 4 performs drive control of the circulation pump 11 and the compressor 21, adjustment of the opening degree of the mixing valve 13 and the expansion valve 23, and control of opening and closing of the defrost valve 32. And so on.

  An operation terminal 36 operable by a user is connected to the main control unit 16 via communication. When, for example, a target hot water supply temperature is set by operating the operation terminal 36, the target hot water supply temperature is transmitted to the main control unit 16. The auxiliary control unit 33 can communicate with the main control unit 16, and controls the compressor 21, the expansion valve 23, the defrost valve 32, and the like of the heat pump heat source unit 3 according to a command from the main control unit 16. . For example, the auxiliary control unit 33 transmits a driving speed and the like to the compressor 21 and receives a current value or a power consumption value when the compressor 21 is driven.

  The control means 4 starts the defrosting operation when the frost formation of the evaporative heat exchanger 24 is detected during the hot water storage operation, and functions as a failure determination means for performing a failure determination of the defrost valve 32 and the expansion valve 23 during the defrosting operation. However, an independent failure determination unit communicatively connected to the control unit 4 may be provided. The failure determination control in the defrosting operation will be described based on the flowchart of FIG. .. In the figure (i = 1, 2,...) Represent steps.

  In S1, it is determined whether frost formation on the evaporative heat exchanger 24 has been detected during the hot water storage operation. If frost formation is detected and the determination is Yes, the process proceeds to S2, and if the determination is No, the process returns to S1. Next, in S2, opening control of the defrost valve 32 is performed, and the process proceeds to S3. The defrost valve 32 is, for example, a normally-closed solenoid valve, and can be opened and closed instantaneously by energization control.

  Next, in S3, within a predetermined time (for example, within 5 seconds) after performing the opening control of the defrost valve 32, the current value or the power consumption value of the compressor 21 is not less than a predetermined value (for example, 1A or more or 100W or more). It is determined whether a drop has been detected. If the defrost valve 32 operates normally, the failure determination of the defrost valve 32 is performed by utilizing the fact that the load on the compressor 21 decreases immediately after opening and the current value or power consumption value of the compressor 21 decreases. Can be done quickly. When the determination is Yes, the process proceeds to S4, and when the determination is No, the process proceeds to S12.

  Next, in S4, since the defrost valve 32 operates normally, the closing control of the expansion valve 23 is performed, and the process proceeds to S5. Since the expansion valve 23 is closed while the defrost valve 32 is open, the discharge side of the compressor 21 is not closed and an excessive load is not applied to the compressor 21. Then, in S5, it is determined whether or not a rise in the refrigerant temperature equal to or higher than a predetermined temperature (for example, 40 ° C.) is detected within a predetermined time (for example, within 40 seconds) after the closing control of the expansion valve 23 is performed. . When the determination is Yes, the process proceeds to S8, and when the determination is No, the process proceeds to S6.

  If the determination in S5 is No, in S6, it is determined that the expansion valve 23 has failed, and the process proceeds to S7. Then, in S7, a failure of the expansion valve 23 is notified, and the process proceeds to S8. The notification of the failure of the expansion valve 23 is performed by, for example, displaying a lamp on the operation terminal 36 or outputting an audio alarm from the operation terminal 36.

  Next, in S8, after the defrosting operation is continued until the defrosting is completed (for example, until a predetermined time elapses or the temperature detected by the outlet temperature sensor 29 reaches a predetermined temperature), the process proceeds to S9. Next, in S9, the expansion valve 23 is opened and the process proceeds to S10. In S10, the defrost valve 32 is closed and the defrosting operation is terminated, and the operation returns to the hot water storage operation.

  On the other hand, if the determination in S3 is No, in S11, it is determined that the defrost valve 32 has failed, and the process proceeds to S12. Then, in S12, the failure of the defrost valve 32 is notified and the defrosting operation is ended to stop the hot water storage operation. The notification of the failure of the defrost valve 32 is performed, for example, by displaying the operation terminal 36 with a lamp or the like or outputting an audio alarm from the operation terminal 36.

Next, the operation and effect of the heat pump water heater 1 of the present invention will be described.
If frost formation on the evaporative heat exchanger 24 is detected during the hot water storage operation, the defrost operation is performed. If the high-temperature refrigerant discharged from the compressor 21 flows through the bypass passage 31 when the defrosting operation is started and the defrosting valve 32 is controlled to open, the pressure on the discharge side of the compressor 21 decreases and the compressor Since the load on the compressor 21 decreases, the current value or the power consumption value of the compressor 21 decreases. On the other hand, if the bypass passage 31 is closed due to the failure of the defrost valve 32 when the defrost valve 32 is controlled to open, the pressure on the discharge side of the compressor 21 does not change and the load on the compressor 21 does not change. Therefore, the current value or power consumption of the compressor 21 does not change. Therefore, it is possible to quickly determine the failure of the defrost valve 32 based on a change in the current value or the power consumption of the compressor 21.

  After the defrost valve 32 is normally opened, the expansion valve 23 is controlled to close. Accordingly, when the bypass passage 31 is closed, the discharge side of the compressor 21 is not closed, and an excessive load is not applied to the compressor 21, so that the failure of the compressor 21 can be prevented. When the expansion valve 23 is closed, low-temperature refrigerant does not flow, so that the defrosting ability does not decrease, and a large change in the refrigerant temperature is detected by the discharge temperature sensor 28 or the outlet temperature sensor 29 as the temperature detecting means. On the other hand, if the expansion valve 23 is not closed due to a failure, the low-temperature refrigerant mixes with the high-temperature refrigerant in the bypass passage 31 and circulates, so that the change in the refrigerant temperature detected by the temperature detecting means is small. Therefore, the failure of the expansion valve 23 can be determined based on the change in the refrigerant temperature detected by the temperature detecting means.

  In addition, the temperature detecting means is the existing discharge temperature sensor 28 or the outlet temperature sensor 29, and the failure of the expansion valve 23 can be determined using the existing temperature detecting means.

  After it is determined that the expansion valve 23 has failed, the defrosting operation may be stopped. The defrosting operation is also executed when the hot water storage is completed, and at this time, the failure determination control of the defrosting valve 32 and the expansion valve 23 may be performed. Further, the heat pump hot water supply device may include, for example, a combustion type auxiliary heating device. In addition, those skilled in the art can implement the above-described embodiment in variously modified forms without departing from the gist of the present invention, and the present invention includes such modified forms.

1: Heat pump hot water supply device 3: Heat pump type heat source device 4: Control means 5: Hot water storage tank 16: Main control unit 21: Compressor 22: Condensing heat exchanger 23: Expansion valve (expansion means)
24: Evaporation heat exchanger 28: Discharge temperature sensor 29: Outlet temperature sensor 30: Outside air temperature sensor 31: Bypass passage 32: Defrost valve 33: Auxiliary control unit

Claims (3)

A heat pump type heat source device configured by connecting a compressor, a condensation heat exchanger, an expansion means, and an evaporative heat exchanger by a refrigerant circuit; a hot water storage tank; and the hot water tank heated by the heat pump type heat source device. Control means for controlling a hot water storage operation for storing hot water in the refrigerant circuit, the refrigerant circuit has a bypass passage for bypassing the expansion means, and a defrost valve for opening and closing the bypass passage, and frost formation on the evaporative heat exchanger is detected. In the case of the heat pump hot water supply device in which the control means opens the defrost valve and closes the expansion means to perform a defrost operation when performed.
When the control unit controls the opening of the defrost valve, a failure determination unit that determines a failure of the defrost valve based on a change in a current value or a power consumption value of the compressor is provided. Heat pump water heater. The refrigerant circuit includes a temperature detection unit that detects a refrigerant temperature during the defrosting operation,
After the failure determination unit determines that the defrost valve is normal in the failure determination, when the control unit controls the closing of the expansion unit, the failure determination unit determines a change in the refrigerant temperature detected by the temperature detection unit. The heat pump hot water supply apparatus according to claim 1, wherein a failure determination of the expansion unit is performed based on the following.   The heat pump hot water supply apparatus according to claim 2, wherein the temperature detection means is disposed on a refrigerant outlet side of the evaporative heat exchanger or on a discharge side of the compressor.