JP2007040555A - Heat pump type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable heat pump type water heater. <P>SOLUTION: The heat pump type water heater is provided with a heat pump circuit sequentially connecting a compressor 11, a hot water supply heat exchanger 12, a solenoid expansion valve 13, and an evaporator 14 by a refrigerant pipe arrangement 15, a hot water supply circuit producing hot water in the hot water supply heat exchanger 12, and a control means for controlling operation of the compressor 11. The reliable heat pump type water heater is provided by not operating the compressor 11 at a maximum operation frequency of hot water supply operation for a predetermined time after finishing defrosting operation of the evaporator 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a refrigeration cycle and control technology during a defrosting operation.

  Conventionally, this type of heat pump type hot water heater performs a defrosting operation when the evaporator is frosted (see, for example, Patent Document 1). A conventional heat pump type water heater will be described below with reference to the drawings.

  FIG. 7 is a diagram illustrating a configuration of a conventional heat pump type hot water heater. As shown in FIG. 7, the heat pump type water heater 100 includes a tank unit 101 and a heat pump unit 102.

  The tank unit 101 includes a hot water tank 103, a circulation pump 104, a mixing valve 105, and a flow rate adjustment valve 106. The bottom pipe of the hot water storage tank 103 is connected to a water supply pipe such as a water pipe through a flow rate adjusting valve 106. Further, the hot water storage tank 103 is connected to the inflow side of the water piping of the hot water supply heat exchanger 107 through the circulation pump 104 from the bottom piping. The upper circulation pipe of the hot water storage tank 103 is connected to the outflow side of the water pipe.

  The heat pump unit 102 is configured by sequentially connecting a hot water supply heat exchanger 107, an expansion valve 108A, a capillary tube 108B, an evaporator 109, and a compressor 110 through a refrigerant pipe 111. Further, a temperature sensor 112 for detecting the temperature of the intake air of the evaporator 109 and a temperature sensor 113 for detecting the temperature near the outlet of the evaporator 109 are provided.

  The operation of the hot water supply operation of the conventional heat pump type hot water heater 100 configured as described above will be described below.

  The operation signal from the hot water storage tank 103 is received, and the operation of the heat pump unit 102 is started. In the heat pump unit 102, the refrigerant compressed by the compressor 110 dissipates heat in the hot water supply heat exchanger 107, is decompressed by the expansion valve 108A and the capillary tube 108B, absorbs heat in the evaporator 109, and is compressed in a gas state. Inhaled into machine 110.

  On the other hand, by the operation of the circulation pump 104, the water in the hot water storage tank 103 is led to the water pipe through the bottom pipe, and the hot water heated by the water pipe passes through the upper circulation pipe to the hot water storage tank 103. Returned.

  Next, the operation of the defrosting operation of the conventional heat pump type hot water heater 100 will be described.

After the defrosting operation is started, the flow rate controlled by the circulation pump 104 is set to a small flow rate so that the heat amount for defrosting is not dissipated by the hot water supply heat exchanger 107. Thereafter, the expansion valve 108A is set to the maximum opening, and the operation frequency of the compressor 110 is increased. And according to the condition of the temperature sensor 113, a defrost operation is complete | finished and a normal hot water supply operation is restarted.
JP-A-2005-147609

However, after the defrosting operation as in the prior art is completed, the capability of the heat pump type hot water heater must be rapidly increased. In order to quickly start up the capacity of the heat pump type hot water heater, it is conceivable to operate the compressor at the maximum operating frequency during hot water supply operation, but if the operation is started at the maximum operating frequency immediately after the defrosting operation is completed. There has been a problem that the pressure of the refrigerant discharged from the compressor rises and exceeds the design pressure.

  This invention solves the said conventional subject, and it aims at providing a reliable heat pump type hot water heater.

  In order to solve the conventional problems, a heat pump type hot water heater of the present invention includes a compressor, a hot water heat exchanger, a decompression means, a heat pump circuit in which an evaporator is sequentially connected by a refrigerant pipe, and the hot water heat exchanger. A hot water supply circuit for generating hot water and a control means for controlling the operation of the compressor, and after the defrosting operation of the evaporator, the compressor has a maximum operating frequency during a hot water supply operation for a predetermined time. I don't drive.

  Thereby, when the heat pump type hot water heater starts normal operation after completion of the defrosting operation, even when the frequency of the compressor during normal operation is set higher than the frequency of the compressor during defrosting operation, An increase in the pressure of the refrigerant discharged from the compressor can be suppressed.

  The present invention can provide a heat pump type hot water heater with high reliability.

A first invention includes a heat pump circuit in which a compressor, a hot water supply heat exchanger, a decompression unit, and an evaporator are sequentially connected by a refrigerant pipe, a hot water supply circuit that generates hot water in the hot water supply heat exchanger, and the compressor Control means for controlling the operation of
After the defrosting operation of the evaporator, the compressor does not operate at a maximum operation frequency during a hot water supply operation for a predetermined time. Thereby, when the heat pump water heater starts normal operation after completion of the defrosting operation, even when the frequency of the compressor during normal operation is set higher than the frequency of the compressor during defrosting operation, Since an increase in the pressure of the refrigerant discharged from the compressor can be suppressed, wear of parts constituting the compressor can be prevented and reliability can be improved.

  The second invention is characterized in that, in particular, in the first invention, the upper limit value of the operating frequency of the compressor is increased stepwise. As a result, wear of parts constituting the compressor is prevented, and the hot water supply operation capacity rises quickly after the defrosting operation is completed.

  The third invention is characterized in that, in particular, in the first or second invention, the refrigerant used in the heat pump circuit is carbon dioxide. As a result, the refrigerant in the hot water supply heat exchanger is pressurized to a critical pressure or higher in order to heat water or air, so it will condense even if heat is taken away by the water in the hot water supply heat exchanger. There is nothing. Therefore, it becomes easy to form a temperature difference between the refrigerant and water over the entire area of the heat exchanger for hot water supply, high-temperature hot water can be obtained, and heat exchange efficiency can be increased.

  However, by using carbon dioxide as the refrigerant, the refrigerant in the hot water heat exchanger is pressurized to a critical pressure or higher. Therefore, by using the first and second inventions described above, even if the refrigerant is pressurized to a critical pressure or higher, it is possible to prevent wear of components constituting the compressor and improve reliability.

In addition, by using relatively inexpensive and stable carbon dioxide for the refrigerant, it is possible to reduce the product cost and improve the reliability. Furthermore, since carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 of the alternative refrigerant HFC-407C, it can provide a product that is friendly to the global environment.

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

(Embodiment 1)
FIG. 1 is a diagram illustrating a configuration of a heat pump type hot water heater in Embodiment 1 of the present invention, and FIG. 2 is a diagram illustrating control of the heat pump type hot water heater in Embodiment 1 of the present invention.

  In FIG. 1, a heat pump type water heater includes a hot water storage tank 16, a water pump 17, a heat exchanger 12 for hot water supply connected in a circular fashion by a pipe 18, a compressor 11, a heat exchanger 12 for hot water supply, a pressure reducing means. A temperature sensor 31 that is a first temperature detection means that detects the temperature of the refrigerant discharged from the compressor 11, and is constituted by a heat pump circuit in which the electromagnetic expansion valve 13 and the evaporator 14 that are A temperature sensor 32 as second temperature detecting means for detecting the temperature of the refrigerant in the vicinity of the outlet of the evaporator 14 is disposed on the heat pump circuit. The temperature sensors 31 and 32 and the electromagnetic expansion valve 13 are controlled by the microcomputer 30. Moreover, since the compressor 11 is a structure without an accumulator, it is small and lightweight. In addition, carbon dioxide is used as the refrigerant circulating in the heat pump circuit.

  In this embodiment, the pressure reducing means is an electromagnetic expansion valve. However, the pressure reducing means is not limited to this, and any pressure reducing means that can determine the opening degree according to the temperature may be used. Further, the refrigerant to be used is not limited to carbon dioxide, and the same effect can be obtained as long as the refrigerant is pressurized to a critical pressure or higher. Further, the temperature sensors 31 and 32 and the electromagnetic expansion valve 13 are controlled by the microcomputer 30, but the microcomputer 30 is not limited to one and may be controlled by using a plurality of microcomputers. In the present embodiment, the temperature of the refrigerant in the vicinity of the outlet of the evaporator 14 is detected to detect the temperature of the refrigerant in the evaporator. The temperature of the refrigerant at the intermediate point of the evaporator 14 or the inlet may be detected without being limited to the outlet.

  Next, the control of the heat pump type hot water heater will be described with reference to FIG. In order to control the temperature of the refrigerant discharged from the compressor 11 detected by the temperature sensor 31 to a desired temperature, the opening degree of the electromagnetic expansion valve 13 is controlled by the pressure reducing device based on the temperature detected by the temperature sensor 31. Controlled by means 33. Further, based on the temperature detected by the temperature sensor 32, the opening degree of the electromagnetic expansion valve 13 is controlled by the pressure reducing device control means 33, and the operation of the compressor 11 is controlled by the compressor operating frequency control means 34. A microcomputer 30 is used for the decompression device control means 33 and the compressor operating frequency control means 34.

  The operation and action of the heat pump type water heater configured as described above will be described below.

  FIG. 3 is a flowchart showing a flow of frequency control of the compressor of the heat pump type hot water heater in Embodiment 1 of the present invention. First, in step 1, after completion of the defrosting operation of the heat pump type hot water heater, when a control start condition such as an increase in the target operating frequency of the compressor 11 is satisfied, the maximum operating frequency of the compressor 11 is set to a predetermined time. Control to limit to a predetermined value is performed.

  In step 2, a timer is started and an upper limit value is set for the operating frequency of the compressor 11 to suppress an increase in the operating frequency of the compressor 11 for a predetermined time. That is, the compressor 11 is suppressed for a predetermined time so as not to operate at the maximum operation frequency during the hot water supply operation.

In step 3, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed, the process returns to step 2 to continue the present control. The control is terminated and the normal hot water supply operation is resumed.

FIG. 4 is a graph showing the operation of the compressor of the heat pump type hot water heater according to Embodiment 1 of the present invention. The dotted line is compared with the conventional control, and the solid line is compared with the main control. In FIG. 4, in the prior art, the pressure of the refrigerant discharged from the compressor 11 exceeds the design pressure and the system is down. By using the control of the present invention, the upper limit of the operating frequency of the compressor 11 is achieved. Since the value is suppressed, the discharge pressure does not exceed the design pressure.
Therefore, it turns out that the overshoot of the temperature and pressure of the refrigerant | coolant discharged from the compressor 11 is prevented by using this invention. Conventionally, the temperature and pressure of refrigerant discharged from the compressor rises, the compressor stops, and it takes time for the compressor to restart, and the heat capacity of the compressor decreases, so it takes a long time to start up. Thus, there is a problem that the hot water supply efficiency is deteriorated, but the problem is also solved, and the transition to the hot water supply operation can be smoothly performed after the defrosting operation is completed.

  As described above, in the first embodiment of the present invention, after the defrosting operation is completed, the operation frequency higher than the operation frequency at the time of defrosting is set by providing an upper limit value for the operation frequency of the compressor 11 and operating for a predetermined time. Even when operating at a frequency, the pressure of the refrigerant discharged from the compressor can be prevented, the compressor can be stopped due to overcurrent of the compressor motor, the compressor can be prevented from being worn, and the equipment constituting the refrigeration cycle can be protected Is possible.

(Embodiment 2)
The heat pump type water heater in the second embodiment of the present invention has the same configuration as that of the first embodiment, and the same parts are denoted by the same reference symbols and description thereof is omitted. Hereinafter, the operation and action in the second embodiment will be described.

  FIG. 5 is a flowchart showing a flow of frequency control of the compressor of the heat pump type hot water heater in Embodiment 2 of the present invention. First, in step 1, after completion of the defrosting operation of the heat pump type hot water heater, when a control start condition such as an increase in the target operating frequency of the compressor 11 is satisfied, the operating frequency of the compressor 11 is determined for a predetermined time. Control to limit to the value.

  In step 2, the timer is started, the current operating frequency of the compressor 11 is stored as α, and the compressor 11 is operated with the maximum operating frequency as α + β until the timer count reaches a predetermined time T. That is, during a predetermined time T, the maximum operating frequency of the compressor 11 is limited to α + β, and is suppressed so as not to be operated beyond that.

  In step 3, it is determined whether the count of the timer has passed a predetermined time T. If the predetermined time T has not passed, the operation is continued with the maximum operating frequency of the compressor 11 being α + β. If T has elapsed, go to Step 4.

  In Step 4, it is determined whether or not the current operating frequency of the compressor 11 has reached the target operating frequency. If the target operating frequency has not been reached, the process returns to Step 2 to newly increase the upper limit value by β, This control is continued, but if the target operating frequency has been reached, this control ends and returns to the normal hot water supply operation.

  FIG. 6 is a graph showing the operation of the compressor of the heat pump type hot water heater according to Embodiment 2 of the present invention, and the dotted line is compared with the conventional control, and the solid line is compared with the main control. In FIG. 6, in the conventional technology, the pressure of the refrigerant discharged from the compressor 11 exceeds the design pressure and the system is down. In this control, the frequency of the compressor 11 is set to α only at a predetermined time T. Since the pressure is not increased, the discharge pressure of the compressor does not exceed the design pressure.

  Therefore, it turns out that the overshoot of the temperature and pressure of the refrigerant | coolant discharged from the compressor 11 is prevented by using this invention. Conventionally, the temperature and pressure of refrigerant discharged from the compressor rises, the compressor stops, and it takes time for the compressor to restart, and the heat capacity of the compressor decreases, so it takes a long time to start up. Thus, there is a problem that the hot water supply efficiency is deteriorated, but the problem is also solved, and the transition to the hot water supply operation can be smoothly performed after the defrosting operation is completed.

  As described above, in the second embodiment of the present invention, after the defrosting operation is completed, the upper limit value of the operation frequency of the compressor 11 is provided in a stepwise manner and operated for a predetermined time, so that the operation frequency at the time of defrosting is obtained. Even when operating at a high operating frequency, it is possible to prevent an increase in the pressure of refrigerant discharged from the compressor, to prevent the compressor from being stopped due to an overcurrent of the compressor motor, to prevent wear of the compressor, and to configure a refrigeration cycle Equipment can be protected.

  As described above, the heat pump type hot water heater according to the present invention prevents an increase in the pressure of the refrigerant discharged from the compressor and can protect the equipment constituting the refrigeration cycle, and thus is limited to the heat pump type hot water heater. However, the present invention can be applied as long as it uses a refrigeration cycle.

The block diagram of the heat pump type water heater in Embodiment 1 of this invention Control diagram of the heat pump water heater Flow chart after completion of defrosting operation of the same heat pump type water heater Comparison of the operation of the compressor of the heat pump type hot water heater with the conventional method The flowchart after completion | finish of the defrost operation of the heat pump type water heater in Embodiment 2 of this invention Comparison of the operation of the compressor of the heat pump type hot water heater with the conventional method Configuration diagram of conventional heat pump water heater

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Compressor 12 Heat exchanger for hot water supply 13 Electromagnetic expansion valve 14 Evaporator 15 Refrigerant piping 16 Hot water storage tank 17 Water pump 18 Piping 30 Microcomputer 31 Temperature sensor 32 Temperature sensor

Claims (3)

A heat pump circuit in which a compressor, a hot water supply heat exchanger, a decompression means, and an evaporator are sequentially connected by a refrigerant pipe, a hot water supply circuit that generates hot water in the hot water supply heat exchanger, and a control that controls the operation of the compressor And the compressor is not operated at the maximum operating frequency during the hot water supply operation for a predetermined time after the defrosting operation of the evaporator is completed. The heat pump type hot water heater according to claim 1, wherein the upper limit value of the operating frequency of the compressor is increased stepwise. The heat pump type water heater according to claim 1 or 2, wherein the refrigerant is carbon dioxide.

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