JP5045656B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater that supplies hot water by storing heated hot water in a hot water storage tank, and particularly relates to an operation method under an operating condition in which an evaporator may be frosted.

  A conventional heat pump water heater is composed of a heat source unit that heats water using a refrigeration cycle and a hot water storage tank unit. The heat source unit includes a compressor that compresses the refrigerant to high temperature and high pressure, a radiator that heats low-temperature water using the refrigerant compressed by the compressor, a decompressor that decompresses the refrigerant cooled by the radiator, and a decompressor And an evaporator for evaporating the refrigerant depressurized in.

  The heat source unit and the hot water storage tank unit are configured such that the low temperature water in the lower part of the hot water storage tank provided in the hot water storage tank unit is supplied to the radiator in the heat source unit, and then the hot water heated by the radiator is It is connected by water piping via a water supply pump so that it may be supplied to the upper part. In the hot water storage tank, low temperature water at the bottom and high temperature water at the top are stored together through a mixed layer.

  The heat pump water heater performs a boiling operation for heating low-temperature water to a predetermined temperature (set boiling temperature). The set boiling temperature is determined from the amount of hot water predicted based on detection values of temperature sensors installed at regular intervals in the vertical direction of the hot water storage tank, the amount of hot water used up to the previous day, and the like. For example, when the amount of hot water used is large, the set boiling temperature is about 85 ° C., and when the amount of hot water used is small, the set boiling temperature is about 65 ° C.

  If the heat pump water heater is kept in a boiling operation under conditions where the outside air temperature is low and there is a lot of moisture in the outside air, the evaporator may form frost and the heating capacity may be reduced.

  Conventionally, as an operation method that can efficiently defrost the frost on the evaporator, the set boiling temperature during the boiling operation can be set in the case where the evaporator is frosted or in the operating conditions where the evaporator may be frosted. A method for increasing the amount of heat stored in the radiator has been proposed (for example, see Patent Document 1).

  According to this, the amount of heat stored in the radiator can be used to quickly melt the frost in the evaporator during the defrosting operation.

  Also, as another conventional operation method, a method of increasing the amount of heat stored in the radiator by performing a defrost preparation operation to increase the set boiling temperature or the discharge temperature of the compressor immediately before entering the defrost operation is also proposed. (For example, refer to Patent Document 2).

Furthermore, in the conventional technique, in order to determine whether or not the operating condition is that the evaporator is frosted, the determination is made that the outside air temperature, the evaporation temperature, or the suction temperature is equal to or lower than a predetermined temperature.
JP 2008-20147 A JP 2007-333341 A

  Originally, it is desirable that the high-temperature water stored in the hot water storage tank has a uniform temperature. If the temperature of the hot water in the hot water storage tank is uneven, when the user uses hot water in the kitchen or bath, the hot water temperature changes greatly, and the hot water tank is installed at regular intervals in the vertical direction. When the amount of hot water stored in the hot water storage tank is predicted based on the detected value of the temperature sensor, there is a problem that an error in the predicted amount of hot water storage becomes large.

  According to the technique described in Patent Document 1, there is a problem that the temperature of the high-temperature water stored in the hot water storage tank becomes nonuniform by changing the set boiling temperature. Moreover, according to the technique described in Patent Document 2, hot water heated by a radiator in a transient state in which the operation mode is switched by performing three operation modes of boiling operation, defrost preparation operation, and defrost operation. As a result, the temperature of the hot water stored in the hot water storage tank becomes uneven.

  Furthermore, in the determination conditions used to determine whether or not the conventional evaporator is in an operating condition for frosting, the outside air temperature is low even under conditions where there is little moisture in the outside air and in fact the frost does not form on the evaporator 14. Therefore, it may be erroneously determined that the operating condition is that the evaporator is frosted. For this reason, an unnecessary defrosting operation is performed, and there is a problem that the temperature of the high-temperature water stored in the hot water storage tank becomes uneven.

  In order to solve the above-described conventional problems, the present invention provides a heat pump water heater that can realize efficient boiling operation and defrosting operation without causing high-temperature water stored in a hot water storage tank to be uneven. The purpose is to do.

In order to solve the conventional problems, the present invention includes a refrigeration cycle formed of a compressor, a radiator, a decompressor, and an evaporator, and a control unit, and the control unit is attached to the evaporator. The defrosting operation determining means for determining the necessity of the defrosting operation for defrosting the frost, and the defrosting operation determining means during the operation of the boiling operation in which water is heated to a predetermined set temperature by the radiator. When the defrosting operation is determined to be necessary, the defrosting operation is performed, and when the boiling operation is performed again after the defrosting operation is completed , the compression is performed more than the boiling operation before the defrosting operation is started. The heat pump water heater is characterized by raising the discharge temperature of the machine, and the discharge temperature is raised without changing the set boiling temperature, so the temperature of the hot water stored in the hot water storage tank is Efficient boiling operation and defrosting without becoming uniform Door can be carried out.

  In addition, the target discharge temperature is not changed during the boiling operation, and the target discharge temperature is changed from the boiling operation immediately after the defrosting operation is performed. Since the temperature of the hot water does not become unstable, efficient boiling operation and defrosting operation can be performed without the temperature of the hot water stored in the hot water storage tank becoming uneven.

  ADVANTAGE OF THE INVENTION According to this invention, the high temperature water stored in a hot water storage tank can be provided, and the heat pump water heater which can implement | achieve efficient boiling operation and defrost operation can be provided.

1st invention is equipped with the refrigerating cycle formed from a compressor, a heat radiator, a decompressor, and an evaporator, and a control means, The said control means defrost operation which defrosts the frost adhering to the said evaporator The need for
A defrosting operation determining unit for determining, and when the defrosting operation determining unit determines that the defrosting operation is necessary during the operation of the boiling operation in which water is heated to a predetermined set temperature by the radiator. When the defrosting operation is performed and the boiling operation is performed again after the defrosting operation is finished , the discharge temperature of the compressor is increased from the boiling operation before the defrosting operation is started. Since the discharge temperature is increased without changing the set boiling temperature, the temperature of the high-temperature water stored in the hot water tank is not uneven, and efficient boiling operation and removal are performed. Frost operation can be performed.

  In addition, the target discharge temperature is not changed during the boiling operation, and the target discharge temperature is changed from the boiling operation immediately after the defrosting operation is performed. Since the temperature of the hot water does not become unstable, efficient boiling operation and defrosting operation can be performed without the temperature of the hot water stored in the hot water storage tank becoming uneven.

  The second invention is characterized in that the boiling operation after the completion of the defrosting operation is performed by raising the target discharge temperature of the compressor and lowering the target frequency of the compressor. Since the target frequency is lowered and the discharge temperature is raised without changing the heating temperature and without changing the set boiling temperature, it can be stored in the hot water storage tank. Efficient boiling operation and defrosting operation can be performed without the temperature of the high-temperature water becoming uneven.

  In addition, the target discharge temperature and target frequency are not changed during the boiling operation, and the target discharge temperature and target frequency are changed from the boiling operation immediately after the defrosting operation is performed. Therefore, the temperature of the hot water heated by the radiator does not become unstable, so the temperature of the hot water stored in the hot water storage tank does not become uneven, and efficient boiling operation and defrosting operation are performed. It can be carried out.

  The third invention includes an incoming water temperature detecting means for detecting the temperature of the water flowing into the radiator and an outside air temperature detecting means for detecting the temperature of the air flowing into the evaporator, and the incoming water temperature detecting means detects the temperature. The target discharge temperature of the compressor is determined based on the received water temperature, the outside air temperature detected by the outside air temperature detecting means, and the boiling set temperature, and the water inlet temperature, the outside air temperature, the setting Even if the boiling temperature changes, the optimum discharge temperature is obtained, and efficient boiling operation and defrosting operation can be performed.

  4th invention is equipped with the incoming water temperature detection means which detects the temperature of the water which flows into a radiator, and the external temperature detection means which detects the temperature of the air which flows into an evaporator, The said incoming water temperature detection means detects The target frequency of the compressor is determined based on the received water temperature, the outside air temperature detected by the outside air temperature detecting means, and the boiling upper set temperature, and the water temperature, the outside air temperature, the set boiling temperature are determined. Even if the upper temperature changes, the optimum target frequency of the compressor is obtained, and efficient boiling operation and defrosting operation can be performed.

  5th invention is equipped with the evaporator temperature detection means which detects the temperature of an evaporator, and performs defrost operation, when the evaporator temperature detected by the evaporator temperature detection means falls more than predetermined temperature within predetermined time. Since the time-dependent change tendency of the evaporator temperature during the boiling operation is used as the determination condition as to whether or not the operation condition requires the defrosting operation, the evaporator is actually High temperature water that is stored in the hot water storage tank without unnecessary defrosting operation because there is no misjudgment that it is an operating condition that requires defrosting operation even though it is not frosted. Efficient boiling operation and defrosting operation can be performed without causing the temperature of the water to become uneven.

The sixth invention is characterized in that when the defrosting operation is continued for a predetermined defrosting time or more, the next boiling operation is performed by increasing the discharge temperature of the compressor. Since the discharge temperature of the compressor increases, the amount of heat stored in the compressor and the radiator during the boiling operation increases. As a result, in the defrosting operation immediately after the next boiling operation, the amount of heat supplied to the evaporator increases, the frost of the evaporator can be melted efficiently, and the efficiency of the defrosting operation is improved.

  The seventh invention is characterized in that when the defrosting operation is performed a predetermined number of times or more within a predetermined operation time, the next boiling operation is performed by increasing the discharge temperature of the compressor. However, since the discharge temperature of the compressor becomes high, the amount of heat stored in the compressor and the radiator during the boiling operation increases. As a result, in the defrosting operation immediately after the next boiling operation, the amount of heat supplied to the evaporator increases, the frost of the evaporator can be melted efficiently, and the efficiency of the defrosting operation is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of the heat pump water heater of the first embodiment. The heat pump water heater includes a heat source unit 50 that heats water using a refrigeration cycle and a hot water storage tank unit 51.

  The heat source unit 50 includes a compressor 11 that compresses the refrigerant to a high temperature and a high pressure, a radiator 12 that heats low-temperature water using the refrigerant compressed by the compressor 11, and a decompression that depressurizes the refrigerant cooled by the radiator 12. And an evaporator 14 for evaporating the refrigerant decompressed by the decompressor 13. The compressor 11, the radiator 12, the decompressor 13, and the evaporator 14 are connected to each other by a refrigerant pipe 15 so that the refrigerant circulates in this order, thereby constituting a refrigeration cycle circuit.

  The refrigeration cycle circuit is filled with carbon dioxide (R744) as a refrigerant. A fan 16 is provided adjacent to the evaporator 14. The fan 16 supplies the outside air to be exchanged with the refrigerant in the evaporator 14 to the evaporator 14.

  In the heat source unit 50 and the hot water storage tank unit 51, low-temperature water in the lower part of the hot water storage tank 30 provided in the hot water storage tank unit 51 is supplied to the radiator 12 in the heat source unit 50 and then heated by the radiator 12. The hot water is connected by a water pipe 32 via a water supply pump 31 so that hot water is supplied to the upper part of the hot water storage tank 30.

  The radiator 12 mainly includes a refrigerant channel 12a and a water channel 12b. The refrigerant flow path 12a and the water flow path 12b are configured so that the refrigerant and water flowing in the respective tubes flow in opposite directions, and the refrigerant and water exchange heat efficiently.

  Further, the discharge temperature detecting means 21 for detecting the refrigerant temperature at any position from the outlet of the compressor 11 to the inlet of the radiator 12, and at any position from the refrigerant inlet to the refrigerant outlet of the evaporator 14 An evaporator temperature detecting means 22 for detecting the refrigerant temperature, an outside air temperature detecting means 23 for detecting the temperature of the outside air flowing into the evaporator 14, and an incoming water temperature detecting means 24 for detecting the temperature of the water flowing into the radiator 12. A hot water temperature detecting means 25 for detecting the temperature of hot water flowing out of the radiator 12 is provided.

  Further, control for controlling the frequency of the compressor 11, the opening of the decompressor 13, the rotational speed of the fan 16 and the water supply pump 31, etc., based on the detected values of the discharge temperature detecting means 21 and the evaporator temperature detecting means 22. Means 40 are provided. In the control means 40, the defrosting operation determining means 41 for determining whether or not the operating condition is necessary to perform the defrosting operation, and the operating condition for which the defrosting operation determining means 41 is required to perform the defrosting operation. A boiling operation control means 42 is provided for controlling so as to perform different boiling operations depending on whether the determination is made or not.

  The compressor 11 may employ a positive displacement fluid mechanism such as a scroll type, a reciprocating type, or a rotary type. A heat exchanger such as a double tube type or a plate type can be adopted as the radiator 12. The evaporator 14 is an air heat exchanger represented by a fin tube type heat exchanger.

  The main operation of the heat pump water heater configured as described above will be described.

  First, the boiling operation will be described. The control means 40 determines the set boiling temperature from the amount of hot water predicted based on the detected value of a temperature sensor (not shown) installed in the hot water storage tank 30, the amount of hot water used up to the previous day, and the like. The boiling operation control means 42 is based on the incoming water temperature detected by the incoming water temperature detection means 24, the outside air temperature detected by the outside air temperature detection means 23, the set boiling temperature, and the determination result of the defrosting operation determination means 41. The target frequency and target discharge temperature of the compressor 11 are selected from a predetermined table. Thereby, even if the incoming water temperature, the outside air temperature, and the set boiling temperature change, it is possible to control so that the optimum target frequency and discharge temperature of the compressor 11 are obtained.

  The compressor 11 is operated by the control means 40 so as to reach the target frequency. The refrigerant is compressed by the compressor 11 to be in a high temperature and high pressure state. Then, after the frequency of the compressor 11 reaches the target frequency, the opening degree of the decompressor 13 is controlled by the control means 40 so that the discharge temperature of the compressor 11 (detected value of the discharge temperature detecting means 21) becomes the target discharge temperature. Controlled by When the refrigerant in the high temperature and high pressure state flows through the refrigerant channel 12 a of the radiator 12, it dissipates heat to the water flowing through the water channel 12 b of the radiator 12 and is cooled.

  The refrigerant that has flowed out of the radiator 12 is decompressed by the decompressor 13, becomes a low-temperature and low-pressure gas-liquid two-phase state, and is supplied to the evaporator 14. In the evaporator 14, the refrigerant is heated by the outside air sent by the fan 16 to be in a gas-liquid two-phase or gas state. The refrigerant that has flowed out of the evaporator 14 is again sucked into the compressor 11.

  On the other hand, the water is sent from the bottom of the hot water supply tank 30 to the water flow path 12b of the radiator 12 by the water supply pump 31, and is heated by the refrigerant flowing through the refrigerant flow path 12a of the radiator 12 to become hot hot water. The hot water is stored from the top of the hot water storage tank 30 through the water pipe 32. At this time, the feed water pump 31 is controlled by the control means 40 so that the hot water temperature (the detected value of the hot water temperature detection means 25) which is the temperature of the hot water flowing out from the radiator 12 becomes the set boiling temperature.

  Next, the defrosting operation will be described. When the heat pump water heater continues the boiling operation under a condition where the outside air temperature is low and the outside air has a lot of moisture, frost is generated in the evaporator 14 and the heating capacity may be reduced. The defrosting operation is an operation for melting the frost of the evaporator 14 in such a case. As a method for the defrosting operation, for example, there is a method in which the rotation speed of the fan 16 and the water supply pump 31 is reduced and the opening of the decompressor 13 is made larger than that in the boiling operation. According to this, the refrigerant that has left the compressor 11 supplies the heat stored in the compressor 11 and the radiator 12 to the evaporator 14 during the boiling operation, and as a result, melts the frost in the evaporator 14. Can do. When the frost in the evaporator 14 melts, the defrosting operation is terminated and the boiling operation is performed again.

  Two operation modes of boiling operation and defrosting operation are repeatedly performed as necessary, and necessary hot water is stored in the hot water storage tank 30 from a detection value of a temperature sensor (not shown) installed in the hot water storage tank 30. Continue driving until it is determined that

  A specific control method for the defrosting operation and the boiling operation described above will be described with reference to the flowchart of FIG. In the present embodiment, since it is not possible to determine whether the defrosting operation needs to be performed before the start of operation or immediately after the start of operation, the defrosting operation determination unit 41 temporarily performs the defrosting operation. It is determined that the operating condition is not necessary.

  For this reason, in step 101 of the flowchart, the boiling operation control means 42 is determined not to be an operation condition that requires the incoming water temperature, the outside air temperature, the set boiling temperature, and the defrosting operation of the defrosting operation determining means 41 to be performed. Based on the result, the target frequency A (Hz-A) and the target discharge temperature A (Td-A) of the compressor 11 are selected from a predetermined table.

  In step 102, boiling operation A is started. In the boiling operation A, the compressor 11 has the target frequency A (Hz-A), and the opening of the decompressor 13 is such that the discharge temperature of the compressor 11 becomes the target discharge temperature A (Td-A). As described above, it is controlled by the control means 40. In step 103, the temperature of the evaporator 14 is detected by the evaporator temperature detecting means 22.

  In step 104, the current evaporator temperature (Te (current)) detected in step 103 and the evaporator temperature (Te (t0 hours before)) detected in step 103 before a predetermined time (t0). An evaporator temperature change amount (ΔTe) which is a difference is calculated. In step 105, it is determined whether or not the evaporator temperature change amount (ΔTe) calculated in step 104 is equal to or greater than a predetermined temperature change amount (ΔTe0). If the evaporator temperature change amount (ΔTe) is equal to or greater than the predetermined temperature change amount (ΔTe0), it is considered that the frost attached to the evaporator 14 grows and the temperature of the evaporator 14 is decreasing.

  For this reason, the defrosting operation determination means 41 determines that the operating condition requires the defrosting operation, and proceeds to step 106. On the other hand, if the evaporator temperature change amount (ΔTe) is less than the predetermined temperature change amount (ΔTe0), it is determined that there is no need to perform the defrosting operation, and the routine returns to step 101 to continue the boiling operation A. To do. In step 106, the defrosting operation is started, and if a predetermined determination condition (not shown) is satisfied, the defrosting operation is terminated. After the defrosting operation is completed, the boiling operation is performed again.

  However, in the present embodiment, the boiling operation after the completion of the defrosting operation is set as the boiling operation B so as to perform a boiling operation different from the boiling operation A before the defrosting operation is performed. That is, in step 107, the boiling operation control means 42 is based on the determination result that the incoming water temperature, the outside air temperature, the set boiling temperature, and the defrosting operation of the defrosting operation determining means 41 are necessary. Based on this, a target frequency B (Hz-B) and a target discharge temperature B (Td-B) of the compressor 11 are selected from a predetermined table.

  Here, the target discharge temperature B (Td-B) is set to be higher than the target discharge temperature A (Td-A), and the target frequency B (Hz-B) is the target frequency A (Hz). It is set to be the same as or lower than -A). In the boiling operation A, the compressor 11 has a target frequency B (Hz-B), and the opening of the decompressor 13 is such that the discharge temperature of the compressor 11 becomes the target discharge temperature B (Td-B). Controlled by the control means 40.

  In step 109, the temperature of the evaporator 14 is detected. In step 110, the difference between the current evaporator temperature (Te (current)) detected in step 109 and the evaporator temperature (Te (t1 hour ago)) detected in step 109 before a predetermined time (t1). An evaporator temperature change amount (ΔTe ′) is calculated. In step 111, it is determined whether the evaporator temperature change amount (ΔTe ′) calculated in step 110 is equal to or greater than a predetermined temperature change amount (ΔTe1).

If the evaporator temperature change amount (ΔTe ′) is equal to or greater than the predetermined temperature change amount (ΔTe1), the defrosting operation determination means 41 determines that the operating condition requires the defrosting operation, and returns to step 106. Then, the defrosting operation is performed again. On the other hand, if the evaporator temperature change amount (ΔTe ′) is less than the predetermined temperature change amount (ΔTe1), it is determined that there is no need to perform the defrosting operation, and Step 1
Proceed to 12.

  In step 112, it is determined whether or not the operation time of the boiling operation B is equal to or longer than a predetermined time (t2). In step 112, when the operation time of the boiling operation B is less than the predetermined time (t2), the process returns to step 107 and the boiling operation B is continued. On the other hand, when the operation time of the boiling operation B is equal to or longer than the predetermined time (t2), it is determined again that the operation condition is not necessary to perform the defrosting operation, the process returns to Step 101, and the boiling operation A is started. Transition.

  Here, if the predetermined time (t2) is set to a sufficiently long time, the transition from the boiling operation B to the boiling operation A, that is, the change of the target discharge temperature and the target frequency during the boiling operation is almost the same. Does not happen. The flowchart of FIG. 2 shows the boiling operation A or the boiling operation B and the defrosting operation until it is determined that necessary hot water has accumulated in the hot water storage tank 30 under a predetermined determination condition (not shown). Repeat.

  By performing such control, in the boiling operation B, the discharge temperature of the compressor 11 becomes higher than the normal boiling operation (boiling operation A). Therefore, the compressor 11 and the radiator are disposed during the boiling operation. The amount of heat stored in 12 increases. As a result, in the defrosting operation immediately after the boiling operation B, the amount of heat supplied to the evaporator 14 is increased, the frost of the evaporator 14 can be efficiently melted, and the efficiency of the defrosting operation is improved.

  Note that if the target discharge temperature B (Td-B) in the boiling operation B is too high, the efficiency during the operation of the boiling operation B decreases, and even if the efficiency of the defrosting operation is improved, The overall efficiency of operation and defrosting operation may decrease. For this reason, it is desirable to set the target discharge temperature B (Td−B) so as to improve the overall efficiency of the boiling operation and the defrosting operation.

  Further, by increasing the target discharge temperature B (Td−B) in the boiling operation B, the heating capacity in the boiling operation B may be higher than the heating capacity in the boiling operation A. Higher heating capacity is not necessarily a good thing, such as changing the operation time required to make a predetermined amount of hot water, so the target frequency B (Hz-B) set in the boiling operation B is It is desirable to make it lower than the target frequency A (Hz-A) set in the boiling operation A.

  According to the present embodiment, the discharge temperature is raised without changing the set boiling temperature, so that the temperature of the high-temperature water stored in the hot water storage tank 30 does not become uneven, and efficient boiling is achieved. An upper operation and a defrosting operation can be performed.

  In addition, the target discharge temperature and target frequency are not changed during the boiling operation, and the target discharge temperature and target frequency are changed from the boiling operation immediately after the defrosting operation is performed. Since the temperature of hot water heated by the radiator 12 does not become unstable, the temperature of the hot water stored in the hot water storage tank 30 does not become uneven, and efficient boiling operation and defrosting operation are performed. And can be done.

  Furthermore, since the target discharge temperature is raised and the target frequency is lowered, there is no problem that the heating capacity changes. Moreover, since the temporal change tendency of the temperature of the evaporator 14 during the boiling operation is used as the determination condition as to whether or not the operation condition requires the defrosting operation, the determination is made before the boiling operation. It is not possible.

  However, since the evaporator 14 is not actually frosted, it is not erroneously determined that the operating condition is necessary to perform the defrosting operation, so that unnecessary defrosting operation is not performed. Efficient boiling operation and defrosting operation can be performed without the temperature of the hot water stored in the hot water storage tank 30 becoming uneven.

(Embodiment 2)
The second embodiment will be described with reference to the flowchart of FIG. In FIG. 3, the same steps as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  When the process proceeds to step 106, the defrosting operation is started, and if a predetermined determination condition (not shown) is satisfied, the defrosting operation is terminated. It progresses to step 201 after completion | finish of a defrost operation. In step 201, the defrosting time is compared with a predetermined time (t3). If the defrosting time is shorter than the predetermined time (t3), the defrosting operation is actually performed although the evaporator 14 is hardly frosted. It returns to step 101, and after step 101, boiling operation A is performed again. On the other hand, when the defrosting time is longer than the predetermined time (t3), the process proceeds to step 107, and the boiling operation B is performed after step 107.

  According to the present embodiment, in addition to the effect described in the first embodiment, the defrosting operation that actually melts the frost of the evaporator 14 in the determination condition as to whether or not the operation condition requires the defrosting operation. Therefore, it is not erroneously determined that the operating condition requires the defrosting operation even though the evaporator 14 is not frosted.

  For this reason, since unnecessary defrosting operation is not performed, the temperature of the high-temperature water stored in the hot water storage tank 30 is further non-uniform, and efficient boiling operation and defrosting operation are performed. It can be performed.

(Embodiment 3)
The third embodiment will be described with reference to the flowchart of FIG. In FIG. 4, the description of the same operation as in FIG. 2 is omitted.

  As preparation before operation, in step 301, the count of the number of defrosts is reset, and in step 302, measurement of the operation time is started after resetting the operation time measurement timer. In step 303, the boiling operation control means 42 is based on the incoming water temperature, the outside air temperature, the set boiling temperature, and the determination result that the defrost operation of the defrost operation determination means 41 is not necessary. The target frequency A (Hz-A) and the target discharge temperature A (Td-A) of the compressor 11 are selected from a predetermined table.

  In step 304, the boiling operation A is started. In the boiling operation A, the compressor 11 has the target frequency A (Hz-A), and the opening of the decompressor 13 is such that the discharge temperature of the compressor 11 becomes the target discharge temperature A (Td-A). As described above, it is controlled by the control means 40. If it is determined that defrosting is necessary in a step that is not shown, the defrosting operation is performed in step 305, and if the predetermined determination condition (not shown) is satisfied, the defrosting operation is terminated. It progresses to step 306 after completion | finish of a defrost operation.

  In step 306, one defrosting count is added. In step 307, the defrosting frequency is compared with a predetermined frequency (n0). If the defrosting frequency is less than the predetermined frequency (n0), the process returns to step 301 and the boiling operation A is performed again after step 301.

  On the other hand, when the defrosting frequency is equal to or greater than the predetermined frequency (n0), the process proceeds to step 308. In step 308, the operation time is compared with a predetermined time (t4). If the operation time is longer than the predetermined time (t4), it is determined that the operation condition does not require frequent defrosting operation, and the process returns to step 301. After step 301, the boiling operation A is performed again.

On the other hand, if the operation time is shorter than the predetermined time (t4), the process proceeds to step 309. In step 309, the boiling operation after the completion of the defrosting operation is set as a boiling operation B, and the boiling operation different from the boiling operation A before the defrosting operation is performed is controlled.

  That is, the boiling operation control means 42 compresses based on the incoming water temperature, the outside air temperature, the set boiling temperature, and the determination result that the defrost operation of the defrost operation determination means 41 is necessary. The target frequency B (Hz-B) and the target discharge temperature B (Td-B) of the machine 11 are selected from a predetermined table.

  Here, the target discharge temperature B (Td-B) is set to be higher than the target discharge temperature A (Td-A), and the target frequency B (Hz-B) is the target frequency A (Hz). It is set to be the same as or lower than -A). In step 310, the boiling operation B is started. In the boiling operation B, the opening degree of the decompressor 13 is set so that the discharge temperature of the compressor 11 becomes the target discharge temperature B (Td-B) so that the compressor 11 becomes the target frequency B (Hz-B). Controlled by the control means 40.

  According to the present embodiment, in addition to the effects described in the first embodiment, on the basis of the fact that the defrosting operation is frequently performed as the determination condition as to whether or not the operation condition requires the defrosting operation. Therefore, it is not erroneously determined that the operating conditions require the defrosting operation even though the evaporator 14 is not frosted.

  For this reason, since unnecessary defrosting operation is not performed, the temperature of the high-temperature water stored in the hot water storage tank 30 is further non-uniform, and efficient boiling operation and defrosting operation are performed. It can be performed.

  The heat pump water heater of the present invention can be applied to a wide range of uses regardless of home use or business use.

1 is a schematic configuration diagram of a heat pump water heater in Embodiment 1 of the present invention. Flow chart of the operation control Flowchart of operation control according to Embodiment 2 of the present invention Flowchart of operation control according to Embodiment 3 of the present invention

DESCRIPTION OF SYMBOLS 11 Compressor 12 Radiator 13 Decompressor 14 Evaporator 16 Fan 21 Discharge temperature detection means 22 Evaporator temperature detection means 23 Outside air temperature detection means 24 Incoming water temperature detection means 25 Hot water temperature detection means 30 Hot water storage tank 31 Water supply pump 40 Control means 41 Defrosting operation determination means 42 Boiling operation control means 50 Heat source unit 51 Hot water storage tank unit

Claims (7)

A refrigeration cycle formed from a compressor, a radiator, a decompressor, and an evaporator, and a control unit are provided, and the control unit determines the necessity of a defrosting operation for defrosting the frost attached to the evaporator. When the defrosting operation determining unit determines that the defrosting operation is necessary during the boiling operation in which water is heated to a predetermined set temperature by the radiator, the defrosting operation determining unit is included. When the frost operation is performed and the boiling operation is performed again after the defrost operation is completed , the discharge temperature of the compressor is increased from the boiling operation before the defrost operation is started. Heat pump water heater. 2. The heat pump water heater according to claim 1, wherein the boiling operation after the defrosting operation is performed by increasing the target discharge temperature of the compressor and decreasing the target frequency of the compressor. An incoming water temperature detecting means for detecting the temperature of water flowing into the radiator, and an outside air temperature detecting means for detecting the temperature of air flowing into the evaporator, the incoming water temperature detected by the incoming water temperature detecting means, The heat pump water heater according to claim 1 or 2, wherein the target discharge temperature of the compressor is determined based on the outside air temperature detected by the outside air temperature detecting means and the boiling upper set temperature. An incoming water temperature detecting means for detecting the temperature of water flowing into the radiator, and an outside air temperature detecting means for detecting the temperature of air flowing into the evaporator, the incoming water temperature detected by the incoming water temperature detecting means, 3. The heat pump water heater according to claim 2, wherein the target frequency of the compressor is determined based on the outside air temperature detected by the outside air temperature detecting means and the set boiling temperature. An evaporator temperature detecting means for detecting the temperature of the evaporator is provided, and a defrosting operation is performed when the evaporator temperature detected by the evaporator temperature detecting means falls below a predetermined temperature within a predetermined time. The heat pump water heater according to any one of 1 to 4. 6. When the defrosting operation continued for a predetermined defrosting time or longer is performed, the next boiling operation is performed by increasing the discharge temperature of the compressor. The heat pump water heater according to item. If the defrosting operation is performed more than a predetermined number of times within the predetermined operation time, the next boiling operation is
The heat pump water heater according to any one of claims 1 to 6, wherein the discharge is performed by increasing a discharge temperature of the compressor.

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