JP6152689B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump hot water supply device, and more particularly to a device that performs defrosting using a defrost valve during a defrosting operation.

  2. Description of the Related Art Conventionally, heat exchange type heat pump water heaters using a refrigerant have been widely used. This type of heat pump water heater includes a heat pump unit that heats hot water with a refrigerant, a hot water storage tank that stores heated hot water, a heating circuit that circulates hot water between the heat pump unit and the hot water storage tank, etc. Use cheap power to circulate hot water in the hot water tank through the heating circuit and heat it with the heat pump unit, and return the hot water to the hot water tank for storage. Hot water is supplied to the hot water supply destination.

  The above heat pump unit is configured by connecting a compressor, a hot water supply heat exchanger, an expansion valve, and an evaporative heat exchanger via a refrigerant pipe, and uses a refrigerant enclosed in a refrigerant circuit to perform hot water supply heating operation. Is done. In this hot water supply heating operation, the compressor and the blower fan for the evaporative heat exchanger are respectively driven, and heat exchange is performed between the refrigerant flowing through the refrigerant circuit and the hot water flowing through the heating circulation circuit by the hot water supply heat exchanger. Hot water is heated.

  By the way, in the heat pump unit described above, due to the structure in which the refrigerant absorbs heat from the outside air with the evaporative heat exchanger, frost is generated by freezing water vapor in the atmosphere attached to the surface of the evaporative heat exchanger in cold regions and winter. May occur. If frost adheres to the evaporative heat exchanger, the endothermic efficiency in the evaporative heat exchanger is significantly reduced, resulting in a problem that the operation efficiency of the heat pump hot water supply device is reduced.

  For this reason, the heat pump hot water supply device is generally provided with a function of a defrosting operation for removing the frost adhering to the evaporation heat exchanger by stopping the hot water supply heating operation. As such a defrosting operation, various techniques described below have been put into practical use.

  For example, in the conventional defrosting operation, the compressor is provided with a four-way valve, and during the defrosting operation, the refrigerant heated by the compressor is caused to flow through the four-way valve in the direction opposite to that during normal operation. Directly flow to the evaporative heat exchanger to remove frost on the evaporative heat exchanger, or provide a bypass circuit that bypasses the hot water heat exchanger, and provides a defrost valve in this bypass circuit. A technique for removing the frost from the evaporation heat exchanger by opening the valve and heating the refrigerant heated by the compressor directly to the evaporation heat exchanger via a bypass circuit has been put into practical use.

  In the refrigeration cycle apparatus of Patent Document 1, a structure is disclosed that includes the bypass circuit and the defrost valve, and an expander that converts energy when the refrigerant expands into electric power or power instead of the expansion valve. ing. During the defrosting operation, the defrost valve is opened to allow the refrigerant to flow into the bypass circuit and increase the rotation speed of the expander to flow the refrigerant into the refrigerant circuit, thereby increasing the refrigerant flow rate to the evaporative heat exchanger. To defrost.

Japanese Patent No. 4053082

  In the conventional structure including the bypass circuit and the defrost valve, when the defrost operation is started, the defrost valve is opened, and the non-compressed refrigerant is discharged from the compressor. Although the defrosting is performed by circulating the refrigerant, the temperature of the refrigerant rapidly decreases in the evaporative heat exchanger. Therefore, the defrosting cannot be effectively performed even if the refrigerant whose temperature has decreased is circulated. That is, since the refrigerant after heat exchange in the evaporative heat exchanger has a shortage of heat, it takes time for defrosting, and the operating efficiency of the heat pump hot water supply device is significantly reduced.

  Further, in the defrosting operation of Patent Document 1, by controlling the rotation speed of the expander, the refrigerant is caused to flow through two circuits, a bypass circuit where the defrost valve is installed and a refrigerant circuit where the expander is installed. Although the refrigerant flow rate to the evaporative heat exchanger is increased, it takes time and effort to control the rotational speed of the expander, which may increase the cost.

  An object of the present invention is to provide a heat pump hot water supply apparatus that can easily and surely shorten the defrosting operation time, and to provide a heat pump hot water supply apparatus that can prevent liquid return to the compressor during the defrosting operation. And so on.

A heat pump hot water supply apparatus according to claim 1 is a heat pump unit in which a compressor, a hot water supply heat exchanger, an expansion means, and an evaporative heat exchanger are connected by a refrigerant circuit, and a bypass provided in the refrigerant circuit and bypassing the expansion means. A heat pump hot water supply device including a circuit and a defrost valve provided in the bypass circuit, and when the frost formation of the evaporative heat exchanger is detected, heat exchange in the heat exchanger for hot water supply is performed. In the heat pump hot water supply apparatus including a defrosting operation control unit that stops and starts the defrosting operation, the defrosting operation control unit is configured to perform the defrosting operation according to a discharge refrigerant temperature of the compressor during the defrosting operation. The defrosting valve is controlled to open and close.

The heat pump hot water supply apparatus according to a second aspect is the invention according to the first aspect , wherein the defrosting operation control means sets the expansion means fully open for a predetermined time at the start of the defrosting operation, and after the predetermined time has elapsed, Control is performed so as to start opening / closing control of the defrost valve.

According to a third aspect of the present invention, there is provided the heat pump hot-water supply apparatus according to the first aspect , wherein the defrosting operation control means sets the expansion means at a start of the defrosting operation until a discharged refrigerant temperature of the compressor becomes a set temperature or lower. It is set to be fully open, and control is performed so as to start opening / closing control of the defrost valve when the temperature becomes equal to or lower than a set temperature.

According to the invention of claim 2, when the heat pump hot water supply device detects frost formation on the evaporative heat exchanger, the heat pump hot water supply device stops the heat exchange in the hot water supply heat exchanger and starts the defrosting operation. Control means, and the defrosting operation control means controls opening and closing of the defrosting valve in accordance with the refrigerant discharge temperature of the compressor during the defrosting operation. When high-temperature and high-pressure refrigerant is stored in the heat exchanger and the defrost valve is open, the high-temperature refrigerant stored in the hot water heat exchanger flows into the evaporative heat exchanger, and the switching control of the open / close state is controlled by the compressor. Defrosting is performed by repeatedly performing according to the discharge refrigerant temperature .
Accordingly, since the high-temperature refrigerant can be repeatedly flowed to the evaporative heat exchanger, the temperature of the refrigerant used for defrosting can be kept high during the defrosting operation, and therefore the defrosting operation time can be shortened. Since it can implement | achieve easily and reliably, the energy saving of a heat pump hot-water supply apparatus can be achieved.

According to the invention of claim 2, the defrosting operation control means sets the expansion means to be fully open for a predetermined time at the start of the defrosting operation, and starts opening / closing control of the defrosting valve after the predetermined time has elapsed. Therefore, at the start of the defrosting operation, the refrigerant is squeezed by the expansion means smaller than the refrigerant circuit cross-sectional area even in the fully opened state, the refrigerant temperature is lowered, the temperature difference between the refrigerant temperature and the outside air temperature is reduced, and the heat of evaporation By limiting the flow rate of the refrigerant to the exchanger, it is possible to suppress a rapid temperature change of the refrigerant in the evaporative heat exchanger and prevent liquid return to the compressor.

According to the invention of claim 3 , at the start of the defrosting operation, the defrosting operation control means sets the expansion means to fully open until the refrigerant discharge refrigerant temperature becomes equal to or lower than the set temperature, and becomes lower than the set temperature. In this case, the opening / closing control of the defrost valve is started, so that the same effect as in the second aspect can be obtained.

It is a schematic block diagram of the heat pump hot-water supply apparatus which concerns on Example 1 of this invention. It is a flowchart of defrost operation control. It is the diagram which showed the refrigerant temperature change at the time of a defrost operation. 6 is a flowchart of defrosting operation control according to the second embodiment.

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

First, the whole structure of the heat pump hot-water supply apparatus 1 of this invention is demonstrated.
As shown in FIG. 1, a heat pump hot water supply apparatus 1 controls a hot water storage hot water supply apparatus 2 having a hot water storage tank 5 for storing hot water, a heat pump heat source apparatus 3 for heating hot water in the hot water storage tank 5, and a heat pump hot water supply apparatus 1. It comprises circulation pipes 8a and 8b for circulating hot water between the control unit 4, the hot water storage hot water supply device 2 and the heat pump heat source unit 3.

  As shown in FIG. 1, a hot water storage and hot water supply apparatus 2 includes a hot water storage tank 5 having a vertically long cylindrical outer peripheral surface, various pipes 6, 7, 8 a and 8 b, a hot water circulation pump 11, an on-off valve 12, a mixing valve 13, A control unit 16, an outer case 17, and the like are provided. The hot water storage tank 5 stores high-temperature hot water (for example, 80 to 90 ° C.) heated by the heat pump heat source unit 3.

  A water supply pipe 6 and a circulation pipe 8 a are connected to the 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 clean water to the hot water storage tank 5. A circulation pipe 8b and a hot water discharge pipe 7 are connected to the upper end of the hot water storage tank 5, and hot hot water returned from the circulation pipe 8b is stored in the hot water storage tank 5. When hot water is supplied, the high temperature in the hot water storage tank 5 is stored. Hot water can be supplied to the hot water supply pipe 7.

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

Next, the heat pump heat source machine 3 will be described.
As shown in FIG. 1, a heat pump heat source unit 3 includes a compressor 21, a hot water supply heat exchanger 22 as a condenser, an expansion valve 23 that rapidly expands a high-pressure refrigerant to lower the temperature and pressure, and evaporation A heat exchanger 24 for absorbing outside air as a heat exchanger, and these devices 21 to 24 are connected via a refrigerant circuit 25 to constitute a heat pump unit 20, and use the refrigerant accommodated in the refrigerant circuit 25. Perform hot water heating operation.

  The heat pump heat source machine 3 further includes a blower fan 27 for an evaporation heat exchanger driven by a blower motor 27a, an auxiliary control unit 33 connected to the main control unit 16 and controlling the heat pump heat source machine 3, and these. An exterior case 35 and the like for housing are provided.

  The compressor 21 is a known hermetic compressor that adiabatically compresses a refrigerant in a gas phase state to increase the temperature. During the defrosting operation, when the defrosting solenoid valve 32 is closed, the compressor 21 adiabatically compresses the refrigerant. When the defrosting solenoid valve 32 is open, the compressor 21 does not compress the refrigerant. And the compressor 21 discharges refrigerant in an uncompressed state.

  The hot water supply heat exchanger 22 is constituted by a double pipe having a heat exchanger passage portion 22 a installed between the circulation pipes 8 a and 8 b and an internal passage 22 b which is a part of the refrigerant circuit 25. In the hot water supply heat exchanger 22, heat is exchanged between the refrigerant flowing through the internal passage 22b and the hot water supplied to the heat exchanger passage portion 22a from the circulation pipe 8a, and the hot water is heated and the refrigerant is cooled and liquefied.

  The expansion valve 23 (corresponding to the expansion means) is for adiabatic expansion of the refrigerant in the liquid phase state to lower the temperature. The expansion valve 23 is a control valve having a variable throttle amount. The expansion valve 23 has a cross-sectional area smaller than that of the refrigerant circuit 25 even in the fully opened state, that is, the expansion valve 23 performs a throttling function even in the fully opened state set during the defrosting operation. There is a temperature difference or a pressure difference between the refrigerant on the outlet side and a bypass circuit 31 described later (see the expansion valve inlet temperature and the expansion valve outlet temperature in FIG. 3).

  The outside air heat absorption heat exchanger 24 includes an evaporator passage portion 24a included in the refrigerant circuit 25. The evaporator passage portion 24a includes a heat transfer tube and a plurality of fins. In the evaporator 24, heat is exchanged between the refrigerant flowing through the evaporator passage portion 24a and the outside air, and the refrigerant absorbs heat from the outside air and vaporizes.

  In the refrigerant circuit 25, a compressor discharge-side temperature sensor 29 a that is provided on the discharge side of the compressor 21 and detects the refrigerant temperature discharged from the compressor 21, and is provided on the outlet side of the heat exchanger 24 for absorbing outside air heat and outside air An evaporative heat exchanger outlet side temperature sensor 29b for detecting the refrigerant temperature flowing out from the heat absorption heat exchanger 24, an expansion valve inlet side for detecting the refrigerant temperature provided on the inlet side of the expansion valve 23 and flowing into the expansion valve 23 There are provided a temperature sensor 29c, an expansion valve outlet side temperature sensor 29d that is provided on the outlet side of the expansion valve 23 and detects the refrigerant temperature flowing out of the expansion valve 23, and the like.

  The refrigerant circuit 25 is provided with a bypass circuit 31 connected to the inlet side and the outlet side of the expansion valve 23 so as to bypass the expansion valve 23. The bypass circuit 31 is provided with a defrosting electromagnetic valve 32 (corresponding to a defrosting valve) that is connected in parallel with the expansion valve 23 and controlled to open and close by the auxiliary control unit 33 during the defrosting operation.

  During the hot water supply heating operation of the heat pump heat source unit 3, the heated refrigerant compressed to a high pressure by the compressor 21 is sent to the hot water supply heat exchanger 22, and the hot water circulation pump 11 is driven to lower the lower end of the hot water storage tank 5. Then, heat is exchanged with water flowing into the heat exchanger passage portion 22a through the circulation pipe 8a to warm the water, and the refrigerant whose temperature is lowered is sent to the expansion valve 23, and the heated hot water passes through the circulation pipe 8b. The hot water is stored in the hot water storage tank 5 of the hot water storage hot water supply device 2 and the hot water is stored in the hot water storage tank 5 by repeating the heating operation via the heat pump heat source unit 3.

Next, the control unit 4 will be described.
As shown in FIG. 1, the heat pump hot water supply apparatus 1 is controlled by a control unit 4 including a main control unit 16 and an auxiliary control unit 33. Detection signals from various temperature sensors and the like are transmitted to the control unit 4, and the control unit 4 controls the operation of the hot water storage hot water supply device 2 and the heat pump heat source unit 3, the operation / stop of various pumps, and the open / close states of various valves. Various operations (heating circulation operation, hot water supply operation, defrosting operation, etc.) are executed by controlling switching and opening degree adjustment.

  The main control unit 16 can perform data communication with the operation remote controller 36 that can be operated by the user. When the target hot water temperature is set by operating the switch of the operation remote controller 36, the target hot water temperature data is transferred from the operation remote controller 36. It is transmitted to the main control unit 16. The auxiliary control unit 33 is capable of data communication with the main control unit 16, and in accordance with instructions from the main control unit 16, various devices (the compressor 21, the expansion valve 23, the blower motor 27 a, the removal device) of the heat pump heat source unit 3. The drive control of the frost electromagnetic valve 32 and the like is performed.

  Next, regarding the defrosting operation control for the outside air heat absorption heat exchanger 24, which is automatically performed when frost formation of the outside air heat absorption heat exchanger 24 is detected, the flowchart of FIG. 2 and the defrosting of FIG. A description will be given based on a diagram showing a temperature change after the start of operation. In the figure, the symbol Si (i = 1, 2,...) Indicates each step. The control program for the defrosting operation control is stored in the control unit 4 in advance.

  In the flowchart of FIG. 2, when this control is started, it is first determined in S1 whether or not a defrosting operation start condition is satisfied. When the condition for starting the defrosting operation is established, that is, when the determination of S1 is Yes, the process proceeds to S2, and when the determination of S1 is No, S1 is repeated.

  As the defrosting operation start condition, for example, the detection signal of the evaporative heat exchanger outlet side temperature sensor 29b is read, and the temperature of the refrigerant discharged from the outside heat absorption heat exchanger 24 is a constant temperature (for example, −5 ° C.). ) The defrosting operation may be started in the following cases, and it is possible to detect that frost is attached to the outside air heat absorption heat exchanger 24 and is installed near the outer periphery of the outside air heat absorption heat exchanger 24. It may be based on a detection signal from the frosting sensor, and various conditions can be adopted and there is no need to particularly limit them.

Next, in S2, the heat exchange in the hot water supply heat exchanger 22 is stopped and the defrosting operation is started (time Ta in FIG. 3), and the process proceeds to S3. Specifically, in the S2, in the savings Yukyu hot water device 2 side, the main control unit 16 stops the driving of the hot water circulating pump 11 stops the hot water supply heating operation.

On the other hand, on the heat pump heat source device 3 side, the auxiliary control unit 33 stops the blower motor 27a, drives the compressor 21, and sets the expansion valve 23 to a fully open state. In this setting, the refrigerant is compressed by the compressor 21 and reaches the expansion valve 23 in a high temperature state without heat exchange in the hot water heat exchanger 22. Even if the expansion valve 23 is set to the fully open state, the expansion function is exerted, so that the refrigerant from the hot water supply heat exchanger 22 is throttled by the expansion valve 23 and the temperature is lowered and flows into the outside air heat absorption heat exchanger 24. To do.

  In this way, the refrigerant temperature of the high-temperature refrigerant is reduced by the fully opened expansion valve 23 to reduce the temperature difference between the refrigerant temperature and the outside air temperature, and the refrigerant flow rate to the outside air heat absorption heat exchanger 24 is limited. Thus, liquid return to the compressor 21 that occurs when a high-temperature refrigerant flows through the outside air heat absorption heat exchanger 24 at once is prevented.

  Next, in S3, the detection signal of the compressor discharge side temperature sensor 29a is read, and it is determined whether or not the temperature of the refrigerant discharged from the compressor 21 is, for example, 50 ° C. or less. In S3, as shown in FIG. 3, the temperature of the refrigerant discharged from the compressor 21 gradually decreases due to the effect of heat exchange in the outside air heat absorption heat exchanger 24 (between time Ta and Tb in FIG. 3). ) When the refrigerant temperature becomes, for example, 50 ° C. or less (time Tb in FIG. 3), that is, when the determination of S3 is Yes, the process proceeds to S4, and when the determination of S3 is No, S3 is repeatedly executed. .

  Next, in S4, the defrosting electromagnetic valve 32 is opened, the bypass circuit 31 is set in a conducting state, 1 is set in the flag F, and the process proceeds to S5. In S4, the compressor 21 is driven as a pump without compressing the refrigerant in accordance with the conduction of the bypass circuit 31, so that the refrigerant in the uncompressed state from the compressor 21 passes through the bypass circuit 31 without flowing through the expansion valve 23. It flows and flows into the outside air heat absorption heat exchanger 24 at a stretch to perform defrosting.

  Next, in S5, the detection signal of the compressor discharge side temperature sensor 29a is read, and it is determined whether or not the temperature of the refrigerant discharged from the compressor 21 is, for example, 28 ° C. or less. In S5, as shown in FIG. 3, the flow rate of the refrigerant increases with the conduction of the bypass circuit 31, and the amount of heat exchange in the outside air heat absorption heat exchanger 24 increases, so the refrigerant discharged from the compressor 21 When the temperature rapidly decreases (between time Tb and Tc in FIG. 3) and the refrigerant temperature becomes 28 ° C. or lower (time Tc in FIG. 3), that is, when the determination of S5 is Yes, the process proceeds to S6. If the determination in S5 is No, the process proceeds to S7.

  Next, in S6, the defrosting electromagnetic valve 32 is closed, the bypass circuit 31 is set to the shielding state, the flag F is set to 0, and the process proceeds to S7. In S6, as shown in FIG. 3, the refrigerant is compressed by the compressor 21, and the refrigerant is stored in the hot water supply heat exchanger 22, whereby the heat storage operation is performed in which the temperature and pressure of the refrigerant rise (see FIG. 3). 3 time Tc-Td). During the heat storage operation, the expansion valve 23 may be maintained in a fully open state or may be fully closed.

  Next, in S7, it is determined whether or not the flag F is 0. In S7, it is determined whether the defrosting electromagnetic valve 32 is in an open state or a closed state. If the defrosting electromagnetic valve 32 is in a closed state (F = 0), that is, if the determination in S7 is Yes, the process proceeds to S8. If the defrosting solenoid valve 32 is open (F = 1), that is, if the determination in S7 is No, the process proceeds to S10.

Next, in S8, the detection signal of the compressor discharge side temperature sensor 29a is read, and it is determined whether or not the temperature of the refrigerant discharged from the compressor 21 is 40 ° C. or higher, for example. In the S8, as shown in FIG. 3, since the thermal storage operation in hot water supply heat exchanger 22 is being performed, the temperature of the refrigerant in the discharge side of the compressor 21 gradually rises, coolant temperature 40 When the temperature is higher than or equal to ° C. (time Td in FIG. 3), that is, when the determination of S8 is Yes, the process proceeds to S9, and when the determination of S8 is No, the process proceeds to S10.

  Next, in S9, the defrosting electromagnetic valve 32 is opened, the bypass circuit 31 is set in a conducting state, 1 is set in the flag F, and the process proceeds to S10. In S9, as in S4, the compressor 21 is driven as a pump with the conduction of the bypass circuit 31, so that the refrigerant in the non-compressed state from the compressor 21 does not flow through the expansion valve 23 but on the bypass circuit 31 side. And flows into the outside air heat absorption heat exchanger 24 at a stretch to perform defrosting.

  Next, in S10, the detection signal of the evaporative heat exchanger outlet side temperature sensor 29b is read to determine whether or not the temperature of the refrigerant discharged from the outside air heat absorption heat exchanger 24 is equal to or higher than a certain temperature (for example, 5 ° C.). . In this S10, as shown in FIG. 3, when the defrosting of the frost adhering to the outside air heat absorption heat exchanger 24 is completed and the refrigerant temperature becomes 5 ° C. or higher (time Te in FIG. 3), that is, When determination of S10 is Yes, it transfers to S11, complete | finishes a defrost operation, and restarts a normal hot water supply heating operation. When the temperature of the refrigerant is 5 ° C. or lower, the defrosting is not completed and the frost is still attached, so the determination in S10 is No, the process returns to S5, and S5 to S9 are repeated.

  Here, as shown in FIG. 3, the temperature of the refrigerant discharged from the outside air heat absorption heat exchanger 24 gradually increases after the start of the defrosting operation (between time Ta and Td). If a high-temperature refrigerant is passed through the outside air heat absorption heat exchanger 24 at a time Td when the defrosting is completed to some extent, the temperature of the refrigerant discharged from the outside air heat absorption heat exchanger 24 rises rapidly. (Time Td-Te), defrosting is completed. If the defrosting electromagnetic valve 32 is maintained in the open state at the time Tb and the defrosting operation is performed, a rapid temperature rise of the refrigerant as described above cannot be expected. Therefore, the defrosting electromagnetic valve 32 is not expected. Compared with the case where the opening / closing control is repeated, the defrosting time becomes longer.

  As described above, the control unit 4 controls the opening / closing of the defrosting electromagnetic valve 32 in accordance with the discharge refrigerant temperature of the compressor 21 detected by the compressor discharge-side temperature sensor 29a, whereby heat exchange for heat absorption by the outside air is performed. Since the high-temperature refrigerant is repeatedly flowed to the heat exchanger 24 to efficiently heat the heat transfer tubes and fins of the heat exchanger 24 for absorbing outside air heat, the defrosting of the heat exchanger 24 for absorbing outside air heat can be performed in a short time. .

  The defrosting operation end condition is based on the detection signal from the evaporative heat exchanger outlet side temperature sensor 29b that detects the temperature of the refrigerant flowing out from the outside air heat absorption heat exchanger 24 in the above. It is not necessary to limit, and based on the detection signal from the frosting sensor which is installed in the vicinity of the outer peripheral portion of the outside air heat absorption heat exchanger 24 and can detect that frost has adhered to the outside air heat absorption heat exchanger 24. Various conditions can be adopted, and there is no need to specifically limit them.

Next, the operation and effect of the heat pump hot water supply apparatus of the present invention will be described.
In the heat pump hot water supply apparatus 1, when the frost formation of the heat exchanger 24 for absorbing outside air heat is detected, the control unit 4 (defrosting operation control means) detects the compressor 21 detected by the compressor discharge side temperature sensor 29a. The defrosting solenoid valve 32 is controlled to open and close according to the discharged refrigerant temperature.

  That is, when the defrosting solenoid valve 32 is in the closed state, high-temperature and high-pressure refrigerant is stored in the hot water supply heat exchanger 22, and when the defrosting electromagnetic valve 32 is in the open state, it is stored in the hot water supply heat exchanger 22. Defrosting is performed by allowing a high-temperature refrigerant to flow through the heat exchanger 24 for absorbing outside air heat, and repeatedly performing switching control of the open / closed state according to the discharge refrigerant temperature of the compressor 21.

  As described above, the control unit 4 performs control to alternately switch the open / close state of the defrosting electromagnetic valve 32 during the defrosting operation, so that the high-temperature refrigerant can be repeatedly flowed to the outside heat absorption heat exchanger 24. Therefore, the temperature of the refrigerant used for the defrosting can be kept high during the defrosting operation, and therefore the defrosting operation time can be shortened easily and reliably. 1 energy saving can be achieved.

  In addition, when the defrosting operation is started, the control unit 4 sets the expansion valve 23 to be fully open until the discharge refrigerant temperature of the compressor 21 becomes equal to or lower than the set temperature, and when the temperature becomes equal to or lower than the set temperature, the defrosting solenoid valve Since the control is performed so as to start the opening / closing control of the refrigerant 32, at the start of the defrosting operation, the refrigerant is throttled by the expansion valve 23 smaller than the sectional area of the refrigerant circuit even in the fully opened state, and the refrigerant temperature is lowered. And the refrigerant flow rate to the outside air heat absorption heat exchanger 24 is restricted, thereby suppressing the rapid temperature change of the refrigerant in the outside air heat absorption heat exchanger 24, and the compressor 21. It is possible to prevent liquid return to the water.

  Next, a second embodiment in which the heat pump hot water supply apparatus 1 of the first embodiment is partially changed will be described. In the first embodiment, the mode for controlling the opening / closing of the defrosting electromagnetic valve 32 according to the discharged refrigerant temperature of the compressor 21 during the defrosting operation has been described. However, in the second embodiment, the cycle is performed during the defrosting operation. A mode for controlling opening / closing of the defrosting electromagnetic valve 32 will be described.

  Defrosting operation control for the outside air heat absorption heat exchanger 24 that is automatically performed when frost formation on the outside air heat absorption heat exchanger 24 is detected will be described with reference to the flowchart of FIG. 4. In the figure, the symbol Si (i = 1, 2,...) Indicates each step. The control program for the defrosting operation control is stored in the control unit 4 in advance. In addition, since S1-S3 and S11 are the same as that of Example 1, description is abbreviate | omitted.

  In S21, the defrosting electromagnetic valve 32 is opened to set the bypass circuit 31 to the conductive state, the flag F is set to 1, a timer is started, and the process proceeds to S22. In S21, the compressor 21 is driven as a pump without compressing the refrigerant in accordance with the conduction of the bypass circuit 31, so that the non-compressed refrigerant from the compressor 21 does not flow through the expansion valve 23 and bypass circuit 31. And flows into the outside air heat absorption heat exchanger 24 at once, and defrosting is performed.

  In step S22, a timer signal is read to determine whether a predetermined time has elapsed. In S22, when a predetermined time has elapsed (for example, 2 minutes when the defrosting solenoid valve 32 is in the open state, 3 minutes when the defrosting electromagnetic valve 32 is in the closed state), that is, if the determination in S22 is Yes, S23 If the predetermined time has not elapsed, that is, if the determination in S22 is No, the process proceeds to S26.

  Next, in S23, it is determined whether or not the flag F is 1. In S23, it is determined whether the defrosting electromagnetic valve 32 is in an open state or a closed state. If the defrosting electromagnetic valve 32 is in an open state (F = 1), that is, if the determination in S23 is Yes, the process proceeds to S24. If the defrosting solenoid valve 32 is closed (F = 0), that is, if the determination in S23 is No, the process proceeds to S25.

  Next, in S24, the defrosting electromagnetic valve 32 is closed and the bypass circuit 31 is set to the shielding state, the flag F is set to 0, the timer is reset once, the start setting is performed, and the process proceeds to S26. . In S24, the refrigerant is compressed by the compressor 21, and the refrigerant is stored in the hot water supply heat exchanger 22, whereby the heat storage operation in which the pressure and temperature of the refrigerant rises is performed.

  On the other hand, in S25, similarly to S21, the defrosting electromagnetic valve 32 is opened to set the bypass circuit 31 to the conductive state, the flag F is set to 1, the timer is reset once, and the start setting is performed. Migrate to

  Next, in S26, the detection signal of the evaporative heat exchanger outlet side temperature sensor 29b is read, and it is determined whether or not the temperature of the refrigerant discharged from the outside air heat absorption heat exchanger 24 is equal to or higher than a certain temperature (for example, 5 ° C.). . As in S10 of the first embodiment, when the defrosting of the frost adhering to the outdoor air heat absorption heat exchanger 24 is completed, the temperature of the refrigerant discharged from the outdoor air heat absorption heat exchanger 24 is increased, and the refrigerant temperature is increased. When it becomes 5 degreeC or more (ie, when determination of S26 becomes Yes), it transfers to S11 and complete | finishes a defrost operation. When the temperature of the refrigerant is 5 ° C. or less, the defrosting is not completed and the frost is still attached, so the determination in S26 is No, the process returns to S22, and S22 to S25 are repeated.

  As described above, the control unit 4 periodically opens and closes the defrosting electromagnetic valve 32, thereby repeatedly flowing a high-temperature refrigerant to the outside air heat absorption heat exchanger 24, and thus the outside air heat absorption heat exchanger 24. Since the heat transfer tubes and fins are efficiently heated, the outside air heat absorption heat exchanger 24 can be defrosted in a short time. Other configurations, operations, and effects are the same as those of the first embodiment, and thus description thereof is omitted.

Next, a mode in which the first and second embodiments are partially changed will be described.
[1] In the first and second embodiments, in S3 of the control program for the defrosting operation control, the expansion valve 23 is set to fully open at the start of the defrosting operation, and the defrosting is performed according to the discharge refrigerant temperature of the compressor 21. While opening the use electromagnetic valve 32, in particular not necessarily limited to this control, the expansion valve 23 is set to a predetermined time fully opened, after the elapse of a predetermined time, the control to open the defrosting electromagnetic valve 32 You may do it.

[2] In the first and second embodiments, instead of the compressor discharge side temperature sensor 29a, a hot water supply heat exchanger inlet side sensor for detecting the refrigerant temperature at the inlet of the hot water supply heat exchanger 22 is provided, and this hot water supply heat exchange is performed. The opening / closing control of the defrosting electromagnetic valve 32 may be performed based on the detection signal of the device inlet side sensor.

[3] In the first and second embodiments, the bypass circuit 31 is provided so as to bypass the expansion valve 23, but may be provided so as to bypass the hot water supply heat exchanger 22 and the expansion valve 23. good. In the case of this structure, during the defrosting operation, the heat storage operation is performed in the refrigerant circuit 25 between the compressor 21 and the expansion valve 23.

[4] In the first and second embodiments, an accumulator may be installed between the heat exchanger 24 for absorbing outside air heat and the compressor 21. In the case of this structure, the liquid return to the compressor 21 can be more reliably prevented by the accumulator.

[5] In addition, those skilled in the art can implement the present invention in various forms with various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. It is.

DESCRIPTION OF SYMBOLS 1 Heat pump hot water supply apparatus 4 Control unit 20 Heat pump unit 21 Compressor 22 Heat exchanger 23 for hot water supply Expansion valve 24 Heat exchanger 25 for external heat absorption 25 Refrigerant circuit 29a Compressor discharge side temperature sensor 29b Evaporative heat exchanger outlet side temperature sensor 31 Bypass circuit 32 Solenoid valve for defrosting

Claims (3)

A heat pump unit in which a compressor, a hot water supply heat exchanger, expansion means, and an evaporative heat exchanger are connected by a refrigerant circuit, a bypass circuit provided in the refrigerant circuit and bypassing the expansion means, and provided in the bypass circuit A heat pump hot water supply device having a defrosting valve, and when frosting of the evaporative heat exchanger is detected, heat exchange in the hot water heat exchanger is stopped and a defrosting operation is started. In the heat pump hot water supply apparatus provided with the defrosting operation control means,
The defrosting operation control means, said during defrosting operation, in response to said discharged refrigerant temperature of the compressor, the heat pump water heater, characterized in that the defrosting valve opening and closing control. The defrosting operation control means sets the expansion means to be fully open for a predetermined time at the start of the defrosting operation, and controls to start opening / closing control of the defrost valve after the predetermined time has elapsed. The heat pump hot water supply apparatus according to claim 1 . The defrosting operation control means sets the expansion means to full open until the refrigerant discharge temperature of the compressor falls below a set temperature at the start of the defrosting operation, and when the defrosting operation control means falls below the set temperature, the defrosting The heat pump hot water supply apparatus according to claim 1, wherein control is performed so as to start valve opening / closing control .