JP2010133598A - Heat pump type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump type water heater enabling stable operation even when a water inflow temperature from a tank to a water heat exchanger is increased during operation maintaining a discharge temperature of a refrigerant to the water heat exchanger in a predetermined range and capable of suppressing cost increase, in the water heater in which refrigerant pressure on the high pressure side is set to exceed critical pressure. <P>SOLUTION: While executing control to adjust the discharge temperature of the refrigerant to the water heat exchanger 21 to the predetermined range, a control part 33 performs control to suppress heat exchange in an evaporator 25 based on rise in the water inflow temperature of water made to flow in to the water heat exchanger 21 through water inflow piping 27. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat pump type water heater.

In general, a heat pump type water heater is a refrigerant circuit in which a compressor, a water heat exchanger, an expansion valve, and an evaporator are connected in this order by piping, a tank in which water is stored, and water in this tank is sent to the water heat exchanger It has a hot water storage circuit having an incoming water pipe and a hot water outlet pipe for returning water heated by the water heat exchanger to the tank (for example, Patent Document 1).
JP 2003-222396 A

  By the way, heat pump type water heaters are used not only for heating water for hot water supply but also for applications such as reheating baths and heating circulating water for floor heating. It tends to be expensive. Further, in the heat pump type hot water supply apparatus, it is necessary to maintain the discharge temperature of the refrigerant from the compressor to the water heat exchanger within a predetermined range in order to maintain the temperature of the hot water from the water heat exchanger to the tank at a predetermined temperature.

  However, in a heat pump water heater that is operated by using, for example, carbon dioxide as the refrigerant and setting the refrigerant pressure on the high-pressure side to be equal to or higher than the critical pressure, when trying to maintain the discharge temperature of the refrigerant from the compressor to the water heat exchanger in a predetermined range, As the incoming water temperature from the tank to the water heat exchanger increases, the refrigerant discharge pressure from the compressor to the water heat exchanger increases. If the discharge pressure rises excessively, a high-pressure protection switch for protecting the device may be activated to stop the operation and prevent normal operation.

  In addition, in the case of a heat pump type water heater that operates with the refrigerant pressure on the high pressure side exceeding the critical pressure, the refrigerant pressure in each device such as a compressor and a water heat exchanger becomes very high. Originally designed to withstand refrigerant pressure. However, if each device is designed with a high safety factor so that it can sufficiently withstand an excessive increase in the discharge pressure as described above, there is a problem that costs increase.

  Accordingly, the present invention has been made in view of such a point, and an object of the present invention is to set a predetermined refrigerant discharge temperature to the water heat exchanger in a water heater that sets the refrigerant pressure on the high-pressure side to a critical pressure or higher. An object of the present invention is to provide a heat pump type hot water heater capable of stable operation even when the temperature of water entering from the tank to the water heat exchanger rises when operating in the range, and suppressing the increase in cost. .

  The heat pump type water heater of the present invention has a compressor (19), a water heat exchanger (21), a pressure reducing mechanism (23), an evaporator (25), and a pipe connecting them, and has a high pressure. The refrigerant circuit (13) for circulating the refrigerant with the refrigerant pressure on the side being equal to or higher than the critical pressure, the tank (15) for storing water, and the water in the tank (15) are sent to the water heat exchanger (21) A hot water storage circuit (17) having a water inlet pipe (27) and a hot water outlet pipe (29) for returning water heated by the water heat exchanger (21) to the tank (15), and the water heat exchanger (21 ) On the basis of an increase in the incoming water temperature of the water flowing into the water heat exchanger (21) through the incoming water pipe (27), while controlling the discharge temperature of the refrigerant to a predetermined range. Control means (33) for performing control to suppress heat exchange in the vessel (25) It has a, and.

  In this configuration, based on the rise of the incoming water temperature, control is performed to adjust the discharge temperature of the refrigerant to the water heat exchanger (21) within a predetermined range in the water heater that sets the high-pressure side refrigerant pressure to a critical pressure or higher. And a control means (33) for executing control for suppressing heat exchange in the evaporator (25). Therefore, by controlling the refrigerant discharge temperature to the water heat exchanger (21) within a predetermined range, the temperature of the hot water from the water heat exchanger (21) to the tank (15) is maintained at the predetermined temperature. On the other hand, it is possible to suppress the increase in the evaporation temperature (evaporation pressure) by executing the control for suppressing the heat exchange in the evaporator (25) based on the increase in the incoming water temperature.

  In the water heater that sets the refrigerant pressure on the high-pressure side to be equal to or higher than the critical pressure, control is performed to adjust the refrigerant discharge temperature to the water heat exchanger (21) within a predetermined range, and the evaporator (25) based on the rise of the incoming water temperature. The conventional water heater that does not control the suppression of heat exchange has the following problems. That is, when the incoming temperature of the water flowing into the water heat exchanger (21) rises, the required evaporation capacity decreases. In this case, when the operation is performed without suppressing the heat exchange in the evaporator (25) and the control is performed to adjust the discharge temperature of the refrigerant to the water heat exchanger (21) within a predetermined range, the evaporator (25) The temperature difference between the refrigerant and the heat exchange object such as the outside air that the evaporator (25) exchanges heat becomes small. That is, the evaporation temperature (evaporation pressure) increases. As a result, in the system in which control is performed to adjust the refrigerant discharge temperature to the water heat exchanger (21) within a predetermined range, refrigerant discharge from the compressor (19) to the water heat exchanger (21) is performed. Pressure will rise.

  On the other hand, in this configuration, the control means (33) controls heat exchange with the refrigerant by suppressing heat exchange in the evaporator (25) so as to meet the required evaporation capacity based on the rise in the incoming water temperature. It can suppress that the temperature difference with a thing becomes small. As a result, an increase in the evaporation temperature (evaporation pressure) can be suppressed, so that an increase in the refrigerant discharge pressure to the hydrothermal exchanger (21) can be suppressed.

  As described above, since the discharge pressure of the refrigerant to the water heat exchanger (21) can be suppressed while maintaining the discharge temperature of the refrigerant to the water heat exchanger (21) within a predetermined range, the apparatus is protected. It is possible to control the operation of the high-pressure protection switch and to design each device by setting the safety factor to an appropriate value. Thereby, the hot water heater can be operated stably, and an increase in cost can be suppressed.

  Specifically, a fan (43) that blows air toward the evaporator (25) is further provided, and the control means (33) adjusts the rotational speed of the fan (43) to adjust the evaporator (25). It is preferable to execute control for suppressing heat exchange in step (b). Thus, the evaporation capability of the evaporator (25) can be controlled by a simple control of adjusting the rotational speed of the fan (43).

  In the present invention, a predetermined reference value serving as a reference for the incoming water temperature is set, and when the incoming water temperature is higher than the reference value, the control means (33) sets the fan (43). It is preferable to execute control for lowering the number of rotations by a predetermined value.

  In this configuration, the predetermined reference value as described above is set, and the rotation speed of the fan (43) is controlled based on this reference value. The number of changes can be reduced. Thereby, control can be simplified, pressing down the important point which should reduce the rotation speed of a fan (43).

  In the present invention, the reference value is a first reference value, and a second reference value having a temperature lower than the first reference value is further set, and the control means (33) is configured to provide the first reference value. After the incoming water temperature becomes higher than the value and the rotational speed of the fan (43) is lowered, the rotational speed of the fan (43) is increased when the incoming water temperature becomes lower than the second reference value. It is preferable to execute the control.

  In this configuration, since the rotation speed of the fan (43) can be controlled not only when the incoming water temperature rises but also when the incoming water temperature falls, the evaporation capacity of the evaporator (25) once lowered can be set to the incoming water temperature. It can be raised again when is lowered. As a result, the hot water heater can be operated more stably by appropriately controlling the rotational speed of the fan (43) even when the incoming water temperature fluctuates up and down over a long period of time.

  Moreover, in this invention, the 3rd reference value of the temperature higher than the said 1st reference value is further set, The said control means (33) becomes the said incoming water temperature higher than the said 1st reference value, and the said After the rotational speed of the fan (43) is lowered, it is preferable to execute stepwise control for further lowering the rotational speed of the fan (43) when the incoming water temperature becomes higher than the third reference value. .

  In this configuration, since stepwise control is performed as described above, the rotational speed of the fan (43) can be decreased stepwise in accordance with the degree of increase in the incoming water temperature. Thereby, since the evaporation capability of an evaporator (25) can be reduced in steps, the discharge pressure of the refrigerant | coolant to a water heat exchanger (21) can be adjusted more finely. Therefore, the operation of the water heater can be further stabilized.

  Further, in the present invention, a fourth reference value having a temperature higher than the second reference value and lower than the third reference value is further set, and the control means (33) is set higher than the third reference value. After the incoming water temperature becomes higher and the rotational speed of the fan (43) is lowered, the rotational speed of the fan (43) is increased in a case where the incoming water temperature becomes lower than the fourth reference value. It is preferable to execute such control.

  In this configuration, since stepwise control is possible even when the incoming water temperature is lowered, the water heater can be further controlled by appropriately controlling the rotational speed of the fan (43) even when the incoming water temperature fluctuates up and down over a long period of time. It is possible to drive stably.

  The control means (33) may execute continuous control for decreasing the rotational speed of the fan (43) as the incoming water temperature increases.

  In this configuration, since the rotation speed of the fan (43) is continuously increased as the incoming water temperature increases, the rotational speed of the fan (43) can be controlled more finely and continuously as the incoming water temperature increases. it can. Thereby, the stability of the water heater can be further improved.

  The control means (33) may execute continuous control for increasing the rotational speed of the fan (43) as the incoming water temperature decreases.

  In this configuration, since the rotational speed of the fan (43) is increased as the incoming water temperature decreases, the rotational speed of the fan (43) is appropriately controlled even when the incoming water temperature fluctuates up and down over a long period of time. Can be effectively suppressed over a long period of time.

  As described above, according to the present invention, it is possible to suppress an increase in the refrigerant discharge pressure to the water heat exchanger while keeping the refrigerant discharge temperature to the water heat exchanger within a predetermined range, thereby protecting the device. It is possible to suppress the operation of the high-pressure protection switch for performing the operation, and it is possible to design each device by setting the safety factor to an appropriate value. Thereby, the hot water heater can be operated stably, and an increase in cost can be suppressed.

  Hereinafter, a heat pump type water heater according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the heat pump type water heater 11 according to the present embodiment boils low temperature water by heat exchange between a refrigerant circuit 13 that circulates refrigerant and the refrigerant in the refrigerant circuit 13, and supplies high-temperature water to a tank 15. And a hot water storage circuit 17 for storing hot water.

  The refrigerant circuit 13 includes a compressor 19, a water heat exchanger 21, an expansion valve (decompression mechanism) 23, an evaporator 25, a pipe connecting them, and a fan 43 that blows air toward the evaporator 25. Have. In the present embodiment, carbon dioxide is used as the refrigerant circulating in the refrigerant circuit 13. This carbon dioxide is compressed to a critical pressure or higher by the compressor 19. The refrigerant exchanges heat with water circulating in the hot water storage circuit 17 in the water heat exchanger 21 to heat the water, and exchanges heat with the outside air in the evaporator 25 to absorb heat from the outside air.

  The hot water storage circuit 17 supplies the tank 15 with water heated by heat exchange between the tank 15 in which water is stored, a water inlet pipe 27 that sends water from the tank 15 to the water heat exchanger 21, and the water heat exchanger 21. A hot water supply pipe 29 to be returned and a pump 31 for circulating water in the hot water storage circuit 17 are provided.

  The temperature of water flowing into the water heat exchanger 21 from the incoming water pipe 27 (hereinafter referred to as incoming water temperature) is measured by a temperature sensor 39 provided in the incoming water pipe 27 in the vicinity of the connecting portion with the water heat exchanger 21. The The temperature of the water whose temperature has been adjusted by the water heat exchanger 21 (hereinafter referred to as the tapping temperature) is measured by a temperature sensor 41 disposed in a tapping pipe 29 in the vicinity of the connection with the water heat exchanger 21.

  The water heater 11 includes a control unit (control means) 33 that controls the refrigerant circuit 13 and the hot water storage circuit 17. The control unit 33 drives the compressor 19 of the refrigerant circuit 13 and also drives the pump 31 of the hot water storage circuit 17, so that low-temperature water in the tank 15 passes through the water inlet pipe 27 from the water outlet provided at the bottom of the tank 15. It is sent to the water heat exchanger 21. The low-temperature water sent to the water heat exchanger 21 is heated in the water heat exchanger 21 and returned to the tank 15 from a water inlet provided in the upper part of the tank 15 through the hot water piping 29. Thereby, in the tank 15, hot water is stored in the upper part, and the temperature of the water is lowered toward the lower part.

  The tank 15 includes a hot water supply pipe 35 for taking out the stored hot water from the upper part of the tank 15 and supplying hot water to a bathtub or the like, and a water supply pipe 37 for supplying low temperature water such as tap water to the bottom of the tank 15. I have.

  FIG. 4 shows the control of adjusting the refrigerant discharge temperature to the water heat exchanger in a predetermined range in the water heater that sets the refrigerant pressure on the high pressure side to a critical pressure or higher, and the heat of the evaporator based on the rise of the incoming water temperature. It is a Mollier diagram in the conventional hot water heater which does not control exchange suppression, and illustrates the refrigeration cycle when the incoming water temperature is 10 ° C, 30 ° C and 50 ° C.

  As described above, when the incoming water temperature rises, the required evaporation capacity decreases accordingly. In this case, if the operation is performed without suppressing the heat exchange in the evaporator and the discharge temperature of the refrigerant to the water heat exchanger is controlled to be substantially constant, the refrigerant temperature (evaporation temperature) in the evaporator is controlled. ) And the outside air that the evaporator exchanges heat.

  Specifically, for example, as shown in FIG. 4, when the incoming water temperature is 10 ° C., 30 ° C., and 50 ° C., for example, the outside air temperature is 8 ° C., and the refrigerant temperature (evaporation temperature) in the evaporator 25 is When the incoming water temperature is 10 ° C., it is about 2 ° C., when the incoming water temperature is 30 ° C., it is about 3 ° C., and when the incoming water temperature is 50 ° C., it is about 4 ° C. When the incoming water temperature increases in this way, the evaporation temperature (evaporation pressure) increases, and as a result, the difference between the evaporation temperature and the outside air temperature becomes smaller.

  The refrigerant that has left the evaporator 25 is compressed by the compressor 19. At this time, in the system that performs control for adjusting the refrigerant discharge temperature to the water heat exchanger 21 to be substantially constant, the refrigerant discharge pressure from the compressor 19 to the water heat exchanger 21 increases. (Refer to the region surrounded by the two-dot chain line in FIG. 4).

  On the other hand, FIG. 2 is a Mollier diagram in the water heater according to the present embodiment, and illustrates refrigeration cycles when the incoming water temperature is 10 ° C., 30 ° C., and 50 ° C., respectively. In this embodiment, the control part 33 performs control which suppresses the heat exchange in the evaporator 25 so that it may correspond to the required evaporation capability based on the raise of incoming water temperature, as shown in the following control examples. Thereby, in the evaporator 25, it can suppress that the temperature difference of external air and a refrigerant | coolant becomes small. As a result, an increase in the evaporation temperature (evaporation pressure) can be suppressed, so that an increase in the refrigerant discharge pressure to the hydrothermal exchanger 21 can be suppressed.

  Next, a control example of the water heater 11 according to the present embodiment will be described. FIG. 3 is a flowchart showing a control example of the water heater 11. In this control example, carbon dioxide is used as the refrigerant, and control for adjusting the discharge temperature of the refrigerant to the water heat exchanger 21 is performed to be substantially constant, and the heat exchange suppression control of the evaporator 25 based on the rise of the incoming water temperature is performed. Execute. In this control example, the heat exchange suppression of the evaporator 25 is performed by reducing the rotational speed of the fan 43 that blows air toward the evaporator 25.

  In this control example, the case where the incoming water temperature at the start of operation is 10 ° C. and the control for decreasing the rotational speed of the fan 43 every time the incoming water temperature rises by 20 ° C. will be described as an example. That is, 30 ° C., which is 20 ° C. higher than the start of operation, is set as the first reference value of the incoming water temperature. Perform stepwise control as a value. In the flowchart of FIG. 3, the temperature rise values from the start of operation are indicated by A1 and A2, and A1 = 20 and A2 = 40, respectively.

  In this control example, the second reference value and the fourth reference value are further set as the reference values for the incoming water temperature. The second reference value is the rotation speed of the fan 43 when the incoming water temperature drops below the first reference value after the incoming water temperature becomes higher than the first reference value and the rotational speed of the fan 43 is lowered. This is a reference value to be raised (returned to the rotation speed at the start of operation). The second reference value is set to 25 ° C., which is 5 ° C. lower than the first reference value (d1 = 5 in the flowchart of FIG. 3). The fourth reference value is the rotation of the fan 43 when the incoming water temperature drops below the third reference value after the incoming water temperature becomes higher than the third reference value and the rotational speed of the fan 43 is lowered. This is the standard value to increase the number. The fourth reference value is set to 45 ° C., which is 5 ° C. lower than the third reference value (d2 = 5 in the flowchart of FIG. 3).

  As shown in FIG. 3, when the operation of the water heater 11 is started, in step S1, the control unit 33 determines the rotational speed of the fan 43 of the evaporator 25 from the outside air temperature, the incoming water temperature, etc., and proceeds to step S2. . The refrigeration cycle when the incoming water temperature is 10 ° C. at the start of operation is as shown in FIG. 2, and the temperature of the refrigerant (evaporation temperature) in the evaporator 25 at this time is about 2 ° C.

  In step S2, the controller 33 determines whether or not the incoming water temperature is higher than a first reference value (for example, 30 ° C.). When the incoming water temperature is higher than the first reference value, the control unit 33 proceeds to step S3. When the incoming water temperature is equal to or lower than the first reference value, the control unit 33 repeats the determination in step S2.

  In step S3, since it is determined in step S2 that the incoming water temperature is higher than the first reference value, the controller 33 evaporates by reducing the rotational speed of the fan 43 by B1 (rpm) from the rotational speed at the start of operation. After suppressing heat exchange in the vessel 25, the process proceeds to step S4. In this control example, as shown in FIG. 2, the rotation speed reduction amount B1 is approximately the same value (about 2 ° C.) as the refrigerant temperature (evaporation temperature) in the evaporator 25 when the incoming water temperature is 30 ° C. It is adjusted to become.

  As described above, when the evaporation capacity required as the incoming water temperature increases, the heat exchange in the evaporator 25 is suppressed to match the temperature difference between the refrigerant in the evaporator 25 and the outside air. The temperature difference can be made substantially the same as when the operation is started, and the temperature difference can be suppressed from becoming small. As a result, it is possible to suppress an increase in the evaporation temperature and the evaporation pressure, and thus it is possible to suppress an increase in the discharge pressure of the refrigerant to the hydrothermal exchanger 21 (see the region surrounded by the two-dot chain line in FIG. 2). ).

  Next, in step S4, the control unit 33 determines whether or not the boiling end condition is satisfied. When the temperature of water at a predetermined height in the tank 15 is equal to or higher than a predetermined value, it is determined that boiling has ended, and the operation ends. If the boiling end condition is not satisfied, the process proceeds to step S5 in order to continue boiling.

  In step S5, the controller 33 determines whether or not the incoming water temperature is lower than a second reference value (for example, 25 ° C.). The second reference value is determined that the incoming water temperature is higher than the first reference value, and after the rotational speed of the fan 43 has been reduced by B1 (rpm) from the start of operation, the incoming water temperature is again increased with time. This is a reference value provided to determine whether or not to increase the rotational speed of the fan 43 and return it to the rotational speed at the start of operation when it falls below the reference value. Therefore, since the incoming water temperature is higher than the second reference value immediately after it is determined in step S2 that the incoming water temperature is higher than the first reference value, the control unit 33 proceeds to step S7 in step S5.

  In step S7, the controller 33 determines whether or not the incoming water temperature is higher than a third reference value (for example, 50 ° C.). The third reference value is determined when the incoming water temperature is further increased over time after it is determined that the incoming water temperature is higher than the first reference value and the rotational speed of the fan 43 is decreased by B1 (rpm). This is a reference value provided for determining whether or not to further reduce the rotational speed of 43. The controller 33 proceeds to step S8 when the incoming water temperature is higher than the third reference value, and returns to step S5 when the incoming water temperature is equal to or lower than the third reference value.

  In step S8, since it is determined in step S7 that the incoming water temperature is higher than the third reference value, the rotation speed of the fan 43 is lowered to B2 (rpm) smaller than the value at the start of operation, and the evaporator 25 After suppressing the heat exchange in step S9, the process proceeds to step S9. In the present control example, the rotational speed reduction amount B2 is larger than the rotational speed reduction amount B1 in step S3 (B2> B1), and in the evaporator 25 when the incoming water temperature is 50 ° C. as shown in FIG. The temperature of the refrigerant (evaporation temperature) is adjusted to be approximately the same value (about 2 ° C.) as at the start of operation.

  In step S9, the control unit 33 determines whether or not the boiling end condition is satisfied. When the temperature of water at a predetermined height in the tank 15 is equal to or higher than a predetermined value, it is determined that boiling has ended, and the operation ends. If the boiling end condition is not satisfied, the process proceeds to step S10 in order to continue boiling.

  In step S10, the control unit 33 determines whether or not the incoming water temperature is lower than a fourth reference value (for example, 45 ° C.). The fourth reference value is determined as the incoming water temperature is higher than the third reference value, and the rotational speed of the fan 43 is lowered to be B2 (rpm) lower than that at the start of operation, and then the incoming water temperature is increased with time. Is a reference value provided to determine whether or not to increase the rotational speed of the fan 43 again when the value falls below the third reference value again. The fourth reference value is set to a temperature that is higher than the second reference value and lower by d2 ° C. (for example, 5 ° C.) than the third reference value.

  Therefore, immediately after it is determined in step S7 that the incoming water temperature is higher than the third reference value, the incoming water temperature is higher than the fourth reference value. Therefore, in step S10, the control unit 33 returns to step S9, and step S9. And the condition judgment of S10 is repeated. While repeating the condition judgment of steps S9 and S10, for example, when the incoming water temperature falls below the fourth reference value, the control unit 33 proceeds to step S11. On the other hand, if the boiling end condition is satisfied while repeating the above condition determination, the control unit 33 ends the operation.

  In step S11, since it is determined in step S10 that the incoming water temperature has become lower than the fourth reference value, the controller 33 evaporates by increasing the rotational speed of the fan 43 to a value smaller by B1 than at the start of operation. After increasing the heat exchange capacity of the vessel 25, the process returns to step S5.

  In step S5, the controller 33 determines whether or not the incoming water temperature is less than the second reference value. If the incoming water temperature falls below the second reference value, the control unit 33 proceeds to step S6.

  In step S6, since it is determined in step S5 that the incoming water temperature has decreased below the second reference value, the control unit 33 returns the rotational speed of the fan 43 to the same value as at the start of operation, and performs heat exchange of the evaporator 25. After increasing the capability, the process returns to step S2 to repeat the above control.

  As described above, in the above-described embodiment, the control is performed to adjust the refrigerant discharge temperature to the refrigerant circuit 13, the hot water storage circuit 17, and the water heat exchanger 21 within a predetermined range. Since the control part 33 which performs control which suppresses the heat exchange in the evaporator 25 based on the raise of the incoming temperature of the water which flows into the heat exchanger 21 is provided, the temperature difference of the refrigerant | coolant in the evaporator 25 and external air Can be suppressed. As a result, the evaporating temperature and the evaporating pressure can be suppressed from increasing, and the refrigerant discharge pressure to the hydrothermal exchanger 21 can be suppressed from increasing.

  Moreover, in the said embodiment, since the fan 43 which ventilates toward the evaporator 25 is further provided and the control part 33 adjusts the rotation speed of the fan 43, it performs control which suppresses the heat exchange in the evaporator 25. The evaporation capability of the evaporator 25 can be controlled by a simple control of adjusting the rotation speed of the fan 43.

  Moreover, in the said embodiment, the predetermined | prescribed 1st reference value used as the reference | standard of incoming water temperature is set, and when the incoming water temperature becomes higher than the 1st reference value, the control part 33 changes the rotation speed of the fan 43. Since the control for lowering by a predetermined value is executed, the rotation speed change of the fan 43 can be determined as a key point and the number of rotation speed changes can be suppressed. Thereby, it is possible to simplify the control while pressing the important point where the rotational speed of the fan 43 should be reduced.

  Moreover, in the said embodiment, the 2nd reference value of temperature lower than a 1st reference value is further set, and the control part 33 becomes higher than a 1st reference value, and the water-inflow temperature becomes low, and reduces the rotation speed of the fan 43. After that, when the incoming water temperature becomes lower than the second reference value, the control for increasing the rotation speed of the fan 43 is executed. Therefore, the evaporation capacity of the evaporator 25 once lowered is increased again when the incoming water temperature decreases. be able to. Thus, the hot water heater can be operated more stably by appropriately controlling the rotational speed of the fan 43 even when the incoming water temperature is fluctuated up and down over a long period of time.

  Moreover, in the said embodiment, the 3rd reference value of temperature higher than a 1st reference value is further set, and the control part 33 becomes higher in water temperature than a 1st reference value, and reduces the rotation speed of the fan 43. After that, when the incoming water temperature becomes higher than the third reference value, stepwise control for further reducing the rotational speed of the fan 43 is executed. Therefore, the rotational speed of the fan 43 is changed stepwise according to the rising degree of the incoming water temperature. Can be lowered. Thereby, since the evaporation capability of the evaporator 25 can be lowered stepwise, the discharge pressure of the refrigerant to the hydrothermal exchanger 21 can be adjusted more finely. Therefore, the operation of the water heater can be further stabilized.

  Moreover, in the said embodiment, the 4th reference value of the temperature higher than a 2nd reference value and lower than a 3rd reference value is further set, and the control part 33 has a higher water inlet temperature than a 3rd reference value. Since the step-by-step control for increasing the rotation speed of the fan 43 is performed when the incoming water temperature becomes lower than the fourth reference value after the rotational speed of the fan 43 is lowered, the fluctuation of the incoming water temperature is increased and decreased over a long period of time. In contrast, the water heater can be more stably operated by appropriately controlling the rotational speed of the fan 43.

  The present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the method of reducing the rotation speed of the evaporator fan is used as a means for suppressing the heat exchange of the evaporator, but the heat exchange suppressing means of the evaporator is not limited to this method. Other methods may be used.

  In the above embodiment, the case where the stepwise control is performed by setting the first reference value to the fourth reference value and setting the rotation speed of the fan of the evaporator to three steps has been described as an example. The control may be four steps or more.

  Moreover, in the said embodiment, the case where the 1st reference value-the 4th reference value are set to 30 degreeC, 25 degreeC, 50 degreeC, and 45 degreeC, respectively is mentioned as an example, when the inflow temperature at the time of an operation start is 10 degreeC. Although explained, each of these reference values is not limited to the above numerical values, and can be appropriately set according to the respective conditions such as the incoming water temperature at the start of operation, the specifications of the hot water heater, and the area of use.

  In the above-described embodiment, the case where stepwise control is performed has been described as an example. However, the control unit may execute continuous control for decreasing the rotational speed of the fan as the incoming water temperature increases. In this embodiment, continuous control is performed to reduce the rotational speed of the fan as the incoming water temperature rises, so that the heat exchange capability (efficiency) in the evaporator can be continuously suppressed as the incoming water temperature increases. Thereby, the stability of the water heater can be further improved.

  In addition to this, the control means may execute continuous control for increasing the rotational speed of the fan as the incoming water temperature decreases. In this configuration, the fan speed is increased as the incoming water temperature decreases, so the fan speed is appropriately controlled even when the incoming water temperature fluctuates up and down over a long period of time. Can be suppressed.

  When such continuous control is executed, for example, the refrigerant temperature (evaporation temperature) and the evaporator pressure (low pressure side pressure) in the evaporator become substantially constant regardless of the rise or fall of the incoming water temperature. An example of control for adjusting the rotational speed of the fan is given.

  In the above embodiment, when the incoming water temperature rises, the fan speed reduction amounts B1 and B2 are set such that the evaporation temperature and the low-pressure side pressure are substantially the same as at the start of operation as shown in FIG. However, the fan rotational speed reduction amount is not limited to the above setting, and the evaporation temperature and the low pressure side pressure may be set to values different from those at the start of operation.

It is a lineblock diagram showing the heat pump type water heater concerning one embodiment of the present invention. It is a Mollier diagram in the hot water supply apparatus concerning this embodiment, and each illustrates the refrigerating cycle when incoming water temperature is 10 degreeC, 30 degreeC, and 50 degreeC. It is a flowchart which shows the flow of control of the water heater concerning this embodiment. It is a Mollier diagram in the conventional water heater, and illustrates the refrigeration cycle when the incoming water temperature is 10 ° C, 30 ° C, and 50 ° C.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Hot water supply machine 13 Refrigerant circuit 15 Tank 17 Hot water storage circuit 19 Compressor 21 Hydrothermal exchanger 23 Expansion valve 25 Evaporator 27 Incoming pipe 29 Hot water outlet 31 Pump 33 Control part 35 Hot water supply pipe 37 Hot water supply pipe 39 Temperature sensor 41 Temperature sensor

Claims (8)

It has a compressor (19), a water heat exchanger (21), a decompression mechanism (23), an evaporator (25), and piping connecting them, and the refrigerant pressure on the high pressure side is set to a critical pressure or higher. A refrigerant circuit (13) for circulating the refrigerant,
A tank (15) in which water is stored, a water inlet pipe (27) for sending water from the tank (15) to the water heat exchanger (21), and water heated by the water heat exchanger (21) A hot water storage circuit (17) having a hot water supply pipe (29) returning to the tank (15);
The incoming water temperature of water flowing into the water heat exchanger (21) through the incoming water pipe (27) while executing control for adjusting the discharge temperature of the refrigerant to the water heat exchanger (21) within a predetermined range. And a control means (33) for executing control to suppress heat exchange in the evaporator (25) based on the rise of the heat pump. A fan (43) for blowing air toward the evaporator (25);
The heat pump type hot water heater according to claim 1, wherein the control means (33) executes control for suppressing heat exchange in the evaporator (25) by lowering a rotational speed of the fan (43). A predetermined reference value serving as a reference for the incoming water temperature is set,
The heat pump hot water supply according to claim 2, wherein the control means (33) performs control to reduce the rotational speed of the fan (43) by a predetermined value when the incoming water temperature becomes higher than the reference value. Machine. The reference value is a first reference value, and a second reference value having a temperature lower than the first reference value is further set.
In the control means (33), the incoming water temperature becomes higher than the first reference value, and after the rotational speed of the fan (43) is lowered, the incoming water temperature becomes lower than the second reference value. The heat pump type hot water heater according to claim 3, wherein control for increasing the rotational speed of the fan (43) is executed. A third reference value having a temperature higher than the first reference value is further set;
In the control means (33), the incoming water temperature is higher than the first reference value, and the incoming water temperature is higher than the third reference value after the rotational speed of the fan (43) is reduced. The heat pump type hot water heater according to claim 4, wherein stepwise control for further reducing the rotational speed of the fan (43) is executed. A fourth reference value that is higher than the second reference value and lower than the third reference value is further set;
In the control means (33), the incoming water temperature becomes higher than the third reference value, and after the rotational speed of the fan (43) is lowered, the incoming water temperature becomes lower than the fourth reference value. The heat pump type hot water heater according to claim 5, wherein stepwise control for increasing the rotational speed of the fan (43) is executed.   The heat pump type hot water heater according to claim 2, wherein the control means (33) performs continuous control to lower the rotational speed of the fan (43) as the incoming water temperature rises. The heat pump type hot water heater according to claim 7, wherein the control means (33) executes continuous control for increasing the rotational speed of the fan (43) as the incoming water temperature decreases.

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