JP4978777B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus. The refrigeration cycle apparatus means an apparatus that performs a refrigerant compression process, a condensation process, an expansion process, and an evaporation process.

  As a refrigeration cycle apparatus, as shown in FIG. 16, a compressor 1Y that performs a compression process for compressing a refrigerant, a heat exchanger 2Y that performs a condensation process for condensing the refrigerant that has passed through the compressor 1Y, and a refrigerant that has undergone a condensation process One having an expansion valve 3Y to be expanded and an air heat exchanger 41Y for performing an evaporation process for evaporating the refrigerant that has passed through the expansion valve 3Y is known. Examples of such a refrigeration cycle apparatus include Patent Documents 1 to 4.

  According to this, the high-temperature and high-pressure refrigerant that has passed through the compressor 1Y performs a condensation step in the condensation heat exchanger 2Y, releases condensation heat, and performs heating. The refrigerant that has undergone the condensing step is expanded by the expansion valve 3Y to reduce the pressure. The refrigerant whose pressure has been reduced by the expansion valve 3Y reaches the air heat exchanger 41Y as an evaporator, performs an evaporation step, and gasification of the refrigerant proceeds. Thereafter, the refrigerant returns to the compressor 1Y and is compressed again. Here, as the above operation continues, the air near the air heat exchanger 41Y is cooled by the air heat exchanger 41Y, and depending on the conditions, moisture of the air causes frost on the surface of the air heat exchanger 41Y. May be generated. As described above, when frost formation on the surface of the air heat exchanger 41Y grows, the heat exchange capacity of the air heat exchanger 41Y decreases, which affects the operation of the refrigeration cycle apparatus.

As described above, when frost is generated on the surface of the air heat exchanger 41Y, the heat exchange efficiency of the air heat exchanger 41Y is lowered, and the heating operation capacity is lowered. In this case, the evaporation temperature in the air heat exchanger 41Y gradually decreases. Therefore, the temperature difference ΔT (ΔT = T1−T2) between the evaporation temperature T2 and the air temperature T1 in the air heat exchanger 41Y increases. Patent Document 1 is that the frost on the surface of the air heat exchanger and 41Y that have occurred discloses a technique for detecting, based on [Delta] T.
Japanese Utility Model Publication No. 61-58433 JP 2002-89992 A JP-A-8-291950 JP-A-5-319077

  In the refrigeration cycle apparatus described above, as shown in FIG. 17, a heat source heat exchanger 42Y that exchanges heat with heat from an external heat source (heated water) is attached to the air heat exchanger 41Y. Yes. According to this apparatus, as shown in FIG. 17, the heat exchanger that performs the evaporation step includes an air heat exchanger 41Y that exchanges heat with air, and a heat source heat exchanger that exchanges heat with the heat of heated water that has cooled the engine. 42Y. In this case, the refrigerant evaporation process is performed in both the air heat exchanger 41Y and the heat source heat exchanger 42Y.

  In this case, if the operation is continued, there is a possibility that the temperature of the refrigerant in the air heat exchanger 41Y will rise due to the transfer of heat from the heat source heat exchanger 42Y. In this case, despite the occurrence of frost formation in the air heat exchanger 41Y, the temperature difference ΔT (ΔT = T1-T2) between the evaporation temperature T2 and the air temperature T1 in the air heat exchanger 41Y decreases. Since it tends to be small, frost formation may not be detected well based on ΔT.

  The present invention has been made in view of the above circumstances, and an evaporation heat exchanger that performs an evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with the heat of the heat source. It is an object of the present invention to provide a refrigeration cycle apparatus that can detect frost formation in an air heat exchanger even when it is provided.

(1) The refrigeration cycle apparatus according to aspect 1 expands a compressor that performs a compression process that compresses the refrigerant, a heat exchanger for condensation that performs a condensation process that condenses the refrigerant that has passed through the compressor, and a refrigerant that has undergone the condensation process. An refrigeration cycle apparatus comprising: an expansion valve to be evaporated; an evaporation heat exchanger that performs an evaporation process for evaporating the refrigerant that has passed through the expansion valve; and a control unit that controls the expansion valve.
(I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with the heat from the heat source.
(Ii) The control unit (a) normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger; ) Operation to reduce the amount of heat transfer per unit time from the heat source heat exchanger to the refrigerant as compared with that in the normal operation mode while flowing the refrigerant through the expansion valve to the air heat exchanger and exchanging heat in the air heat exchanger performed and frost formation determination mode for,
(Iii) The expansion valve is a first expansion valve provided between the heat exchanger for condensation and the air heat exchanger, and a second expansion provided between the heat exchanger for condensation and the heat source heat exchanger. With a valve,
In the frost determination mode, the control unit sets the opening of the second expansion valve connected to the heat source heat exchanger to 0 or reduces the opening of the second expansion valve as compared with the normal operation mode, The refrigerant flow rate per unit time flowing toward the heat exchanger is reduced to 0 or less than in the normal operation mode .

According to this aspect, in the normal operation mode, the control unit exchanges heat in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to both the air heat exchanger and the heat source heat exchanger. I do. Thereby, the refrigerant | coolant evaporation process is implemented.

  A control part performs frosting determination mode regularly or irregularly. In the frosting determination mode, the control unit flows the refrigerant that has passed through the expansion valve to the air heat exchanger and performs heat exchange in the air heat exchanger, and also calculates the heat transfer amount per unit time from the heat source heat exchanger to the refrigerant. Decrease than in normal operation mode. In this case, the heat of the heat source heat exchanger is suppressed from being transmitted to the air heat exchanger.

  Here, when frost is generated on the surface of the air heat exchanger, the heat exchange efficiency in the air heat exchanger is lowered, and the evaporation capability in the air heat exchanger is lowered. Therefore, the evaporation process of the refrigerant in the air heat exchanger is impaired, and the pressure of the refrigerant in the air heat exchanger gradually decreases. In this case, the evaporation temperature in the air heat exchanger gradually decreases, and the evaporation temperature T2 in the air heat exchanger gradually decreases. Therefore, the temperature difference ΔT (ΔT = T1−T2) between the air temperature T1 and the evaporation temperature T2 in the air heat exchanger increases. Since the temperature difference ΔT increases in this way, it is effectively detected based on ΔT that frost formation has occurred in the air heat exchanger.

According to this aspect , in performing the frost determination mode, an operation is performed to reduce the amount of heat transfer per unit time from the heat source heat exchanger to the refrigerant as compared to the normal operation mode. For this reason, in the frost determination mode, the amount of heat transfer from the heat source heat exchanger to the air heat exchanger is suppressed. As a result, the evaporation temperature T2 in the air heat exchanger decreases. Therefore, the temperature difference ΔT (ΔT = T1−T2) between the air temperature T1 and the evaporation temperature T2 in the air heat exchanger can be increased. Therefore the temperature difference [Delta] T is increased so, that the frost in the air heat exchanger that has occurred can be well detected on the basis of the [Delta] T.

In this case, the control unit, in the frost determination mode, (i) a heat transfer amount reducing means for reducing the heat transfer amount per unit time from the heat source heat exchanger to the refrigerant than in the normal operation mode, and (ii) air The form provided with the temperature difference means which measures the temperature difference of the evaporation temperature in a heat exchanger and air temperature, and the frost determination means which determines a frost state based on a temperature difference is illustrated. The frost determining means, Ru can be satisfactorily performed on the basis of the determination of the frosting condition in the air heat exchanger to the temperature difference ΔT as described above.

According to the refrigeration cycle apparatus according to this aspect , the expansion valve includes the first expansion valve provided between the condensation heat exchanger and the air heat exchanger, the condensation heat exchanger, and the heat source heat exchanger. And the control unit sets the opening of the second expansion valve to 0 or sets the opening of the second expansion valve to the normal operation mode in the frosting determination mode. It is characterized by being reduced more than the case. Thereby, the refrigerant | coolant flow volume per unit time which flows into a heat-source heat exchanger is stopped or reduced rather than the case of normal operation mode. As a result, in the frosting determination mode, the heat transfer amount per unit time from the heat source heat exchanger to the refrigerant can be reduced as compared with the normal operation mode. Therefore, the temperature difference ΔT described above is ensured. For this reason, frost formation is satisfactorily detected based on the temperature difference ΔT.

(2) The refrigeration cycle apparatus according to aspect 2 expands the compressor that performs the compression process for compressing the refrigerant, the heat exchanger for condensation that performs the condensation process for condensing the refrigerant that has passed through the compressor, and the refrigerant that has undergone the condensation process. An refrigeration cycle apparatus comprising: an expansion valve to be evaporated; an evaporation heat exchanger that performs an evaporation step for evaporating the refrigerant that has passed through the expansion valve; and a control unit that controls the expansion valve.
  (I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with the heat from the heat source.
  (Ii) The control unit
  (A) a normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger;
  (B) The refrigerant that has passed through the expansion valve is passed through the air heat exchanger to perform heat exchange in the air heat exchanger, and the amount of heat transferred from the heat source heat exchanger to the refrigerant per unit time is greater than that in the normal operation mode. And the frosting determination mode to perform the operation to reduce the
  (Iii) The expansion valve is a common expansion valve formed by a three-way valve having a port connected to the heat exchanger for condensation, a port connected to the air heat exchanger, and a port connected to the heat source heat exchanger,
  In the frost determination mode, the control unit sets the opening degree of the port connected to the heat source heat exchanger in the common expansion valve to 0 or decreases it compared to the case of the normal operation mode, thereby toward the heat source heat exchanger. The flow rate of the refrigerant per unit time is reduced to 0 or less than in the normal operation mode.

  According to this aspect, in the frost determination mode, the control unit sets the opening degree of the port connected to the heat source heat exchanger in the common expansion valve to 0 or decreases it compared to the normal operation mode. The refrigerant flow rate per unit time flowing toward the heat exchanger is reduced as compared with the normal operation mode.

  (3) The refrigeration cycle apparatus according to aspect 3 expands the refrigerant that has undergone the compression process, the heat exchanger for condensation that performs the condensation process that condenses the refrigerant that has passed through the compressor, and the refrigerant that has undergone the condensation process. An refrigeration cycle apparatus comprising: an expansion valve to be evaporated; an evaporation heat exchanger that performs an evaporation process for evaporating the refrigerant that has passed through the expansion valve; and a control unit that controls the expansion valve.
  (I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with the heat from the heat source.
  (Ii) The control unit
  (A) a normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger;
  (B) The refrigerant that has passed through the expansion valve is passed through the air heat exchanger to perform heat exchange in the air heat exchanger, and the amount of heat transferred from the heat source heat exchanger to the refrigerant per unit time is smaller than that in the normal operation mode. And the frosting determination mode for performing the operation
  (Iii) The expansion valve is provided between the heat exchanger for condensation, the air heat exchanger, and the heat source heat exchanger,
  In the frosting determination mode, the control unit adjusts the opening degree of the expansion valve connected to the heat source heat exchanger so that the refrigerant flow rate per unit time flowing toward the heat source heat exchanger is 0 or in the normal operation mode. Is also reduced.

  In the frosting determination mode, the control unit adjusts the opening degree of the expansion valve connected to the heat source heat exchanger so that the refrigerant flow rate per unit time flowing toward the heat source heat exchanger is 0 or in the normal operation mode. Also reduce.

  According to the present invention, in carrying out the frosting determination mode, the amount of heat transfer per unit time from the heat source heat exchanger to the refrigerant is reduced as compared with the normal operation mode. For this reason, in carrying out the frost determination mode, it is possible to increase the above-described temperature difference ΔT that serves as a standard for frost determination. Therefore, the accuracy of frost determination can be improved. Therefore, even when the evaporation heat exchanger performing the evaporation process includes an air heat exchanger that exchanges heat with air and a heat source heat exchanger that exchanges heat with the heat of the heat source, the heat source heat exchanger The amount of heat transferred from the air to the air heat exchanger is limited. Therefore, frost formation in the frost determination mode can be determined satisfactorily.

  The refrigeration cycle apparatus is an apparatus that performs a refrigeration cycle of a refrigerant compression process, a refrigerant condensation process, a refrigerant expansion process, and a refrigerant evaporation process, and has a heating function and / or a cooling function. An example of the heating function is a heating function. The cooling function includes a cooling function.

  -When performing the normal operation mode, the operation mode may be switched to the frost determination mode as necessary. Switching to the frosting determination mode may be performed after the set time has elapsed from the start of the normal operation mode, may be repeated every set time, or after the set time has elapsed since the end of the defrost mode described later. Also good.

  -In the frosting determination mode, the refrigerant flow rate per unit time flowing through the heat source heat exchanger may be stopped or decreased as compared with the normal operation mode. In this case, the refrigerant circulation amount in the refrigeration cycle apparatus is reduced. Therefore, the flow rate per unit time of the refrigerant flowing through the evaporating heat exchanger decreases, and the evaporation amount in the evaporating heat exchanger that performs the evaporating process may decrease. In this case, the amount of condensation heat released from the condensation heat exchanger that performs the condensation process per unit time may be reduced, and the capacity of the refrigeration cycle apparatus may be reduced.

  Then, in such a case, it is illustrated that a control part implements a 1st control form and a 2nd control form. According to the 1st control form, in the frost determination mode, the opening degree of the 1st expansion valve connected with an air heat exchanger is increased rather than the case of normal operation mode. Thereby, the refrigerant | coolant flow rate per unit time which flows through an air heat exchanger increases compared with the case of normal operation mode. As a result, the flow rate per unit time of the refrigerant flowing through the evaporation heat exchanger performing the evaporation step is ensured. Therefore, the evaporation amount in the evaporation heat exchanger that performs the evaporation process is secured. In this case, a decrease in the amount of condensation heat released from the heat exchanger for condensation that performs the condensation step is suppressed. Therefore, the capability fall of a refrigerating cycle device is controlled.

  -As mentioned above, in the frost determination mode, the refrigerant circulation amount in the refrigeration cycle apparatus may decrease. Therefore, according to the second control mode, the control unit increases the rotation speed (drive amount) of the compressor per unit time in the frost determination mode than in the normal operation mode. In this case, since the refrigerant circulation amount in the refrigeration cycle apparatus is ensured, a decrease in the capacity of the refrigeration cycle apparatus is suppressed.

  -The smaller the temperature difference described above, the smaller the degree of frost formation in the air heat exchanger. The greater the temperature difference described above, the greater the degree of frost formation in the air heat exchanger. Therefore, in the frosting determination mode, the control unit detects the temperature difference while shifting the time, and detects that the temperature difference is increasing with time, and determines that the frost is growing. The form which has a frost growth determination means is illustrated. When it is determined that the frost is growing, the control unit preferably increases the defrosting capability for increasing the defrosting time and / or the defrosting capability in the defrosting process.

  Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 shows a system diagram of a refrigeration cycle apparatus (cooling cycle apparatus). The evaporation temperature of the refrigeration cycle does not mean the freezing point or lower, but includes a form in which the evaporation temperature is higher than the freezing point. As shown in FIG. 1, the refrigeration cycle apparatus includes a compressor 1 that performs a compression step of compressing a refrigerant to obtain a high temperature and high pressure, and a heat exchange for condensation that performs a condensation step of condensing the high temperature and high pressure refrigerant that has passed through the compressor 1. 2, expansion valve 3 that expands the pressure of the refrigerant that has undergone the condensing process to lower the pressure, heat exchanger 4 for evaporation that performs the evaporating process of evaporating the refrigerant that has passed through expansion valve 3, and the degree of opening of expansion valve 3 is controlled And a control unit 6 for performing the above operation. The control unit 6 has a memory 60 and a CPU 61.

  The condensation heat exchanger 2 is disposed indoors and functions as an indoor heat exchanger. The heat exchanger 2 for condensing has a fan 2f and enhances heat exchange with the indoor air (medium). The evaporation heat exchanger 4 that performs the evaporation step includes an air heat exchanger 41 that exchanges heat with air, and a heat source heat exchanger 42 that exchanges heat with heat from the heat source. Since the air heat exchanger 41 is disposed outdoors, it functions as a first outdoor heat exchanger. Since the heat source heat exchanger 42 is disposed outside, it functions as a second outdoor heat exchanger. The air heat exchanger 41 has a fan 41f and enhances heat exchange with indoor air (medium).

  The heat source heat exchanger 42 has a heated water passage 43 (heated fluid passage) that is connected to the heat generation source 45 while flowing heated water (heated liquid) in a hot water state. The heat generation source 45 may be an engine, an electric heater, a fuel cell system, or a gas engine cogeneration (power generation and heat utilization). Since the heated water receives heat from the heat generation source 45 and is in a warm water state, it functions as a heat source that promotes evaporation of the refrigerant in the heat source heat exchanger 42. The heating water passage 43 is provided with a supply valve 44v (heating liquid supply element) and a pump 44p (heating liquid conveyance source). The opening degree of the supply valve 44v and the driving force of the pump 44p affect the amount of heat transferred to the heat source heat exchanger 42. Accordingly, the supply valve 44v and the pump 44p function as a heat amount adjusting unit that adjusts the amount of heat transferred to the heat source heat exchanger 42.

  Further, as shown in FIG. 1, an air temperature sensor 51 is provided for detecting the temperature T1 of the air (outside air) where the air heat exchanger 41 is arranged. A heat exchange temperature sensor 52 that detects the evaporation temperature T2 in the air heat exchanger 41 is provided. The heat exchanger temperature sensor 52 is provided on the outlet 41o side of the air heat exchanger 41 in consideration of the evaporation of the refrigerant in the air heat exchanger 41. However, the present invention is not limited thereto, and when the heat exchange passage length in the air heat exchanger 41 is relatively displayed as 100, the heat is placed at a position within 70 or 50 from the outlet 41o of the air heat exchanger 41 toward the inlet 41i. An alternating temperature sensor 52 can also be arranged. Temperature signals from the air temperature sensor 51 and the heat exchanger temperature sensor 52 are input to the control unit 6. The control unit 6 controls the first expansion valve 31, the second expansion valve 32, the compressor 1, the supply valve 44v, and the pump 44p.

  As shown in FIG. 1, the air heat exchanger 41 and the heat source heat exchanger 42 are in parallel with each other, but are in series with the heat exchanger 2 for condensation. A first expansion valve 31 is provided between the condensation heat exchanger 2 and the air heat exchanger 41. A second expansion valve 32 is provided between the condensation heat exchanger 2 and the heat source heat exchanger 42. The first expansion valve 31 and the second expansion valve 32 can be variable valves whose opening degree is variable continuously or in multiple stages, but may be on / off valves whose opening degree can be switched between 100% and 0%.

  According to the normal operation mode, the compressor 1 is driven to generate a high-temperature and high-pressure gaseous refrigerant. The gaseous high-temperature and high-pressure refrigerant compressed by the compressor 1 is discharged from the discharge port 1o of the compressor 1 and performs a condensation step in the condensation heat exchanger 2 to release the condensation heat. Thus, the heating operation is performed. The rotation of the fan 2f ensures the release of condensation heat. The refrigerant that has undergone the condensing step is branched at the branch point 9a. The branched refrigerant is expanded by the first expansion valve 31 and reduced in pressure (gas-liquid mixed state), and then flows into the air heat exchanger 41 to perform heat exchange in the air heat exchanger 41. Further, the branched refrigerant is expanded by the second expansion valve 32 and reduced in pressure (gas-liquid mixed state), and then flows into the heat source heat exchanger 42 to perform heat exchange in the heat source heat exchanger 42.

  Thereby, the evaporation process of the refrigerant is performed in both the air heat exchanger 41 and the heat source heat exchanger 42. That is, the refrigerant whose pressure has been reduced by the first expansion valve 31 reaches the air heat exchanger 41 as an evaporator, performs an evaporation process, and gasification of the refrigerant proceeds. The refrigerant whose pressure has been reduced by the second expansion valve 32 reaches the heat source heat exchanger 42 as an evaporator, performs an evaporation process, and the gasification of the refrigerant proceeds. Thereafter, the evaporated refrigerant returns to the suction port 1s of the compressor 1, is compressed again, and is discharged from the discharge port 1o toward the condensation heat exchanger 2. Thus, the heating operation in the normal operation mode is performed.

Here, when the heating operation in the normal operation mode described above continues, the air near the air heat exchanger 41 is cooled by the air heat exchanger 41. Depending on conditions, moisture in the air may generate frost on the surface of the air heat exchanger 41. When frosting occurs on the surface of the air heat exchanger 41 in this manner, the heat exchange efficiency of the air heat exchanger 41 is reduced, so that the heat exchange efficiency in the air heat exchanger 41 is lowered. Therefore, the refrigerant evaporation process in the air heat exchanger 41 is impaired, the refrigerant evaporation amount is suppressed, and the refrigerant pressure in the air heat exchanger 41 gradually decreases. In this case, the evaporation temperature T2 (the temperature detected by the heat exchanger temperature sensor 52) in the air heat exchanger 41 gradually decreases. Therefore, the temperature difference ΔT between the air temperature T1 and the evaporation temperature T2 in the air heat exchanger 41 increases. Therefore, the frost in the air heat exchanger 41 that has occurred is detected by the control unit 6 on the basis of the [Delta] T.

  However, according to the present embodiment, as shown in FIG. 1, the heat source heat exchanger 42 for exchanging heat between the heat of the heat source (heated water in the hot water state) and the heat of the refrigerant is provided. In this case, the refrigerant evaporation process is performed in both the air heat exchanger 41 that exchanges heat with air and the heat source heat exchanger 42 that exchanges heat with heat from the heat source. In this case, if the operation is continued, the refrigerant pressure of the air heat exchanger 41 increases due to the transfer of heat from the heat source (heated water in the hot water state) of the heat source heat exchanger 42, and the temperature of the refrigerant of the air heat exchanger 41 increases. May rise. In this case, the temperature difference ΔT (ΔT = T1−T2) between the air temperature T1 and the evaporation temperature T2 in the air heat exchanger 41 is decreased despite the occurrence of frost formation on the surface of the air heat exchanger 41. To do. For this reason, although frost formation has occurred in the air heat exchanger 41, the frost formation may not be detected well. Therefore, according to the present embodiment, the controller 6 performs the frost determination mode regularly or irregularly while performing the heating operation. In this case, during the heating operation, the control unit 6 flows the refrigerant that has passed through the first expansion valve 31 to the air heat exchanger 41 to perform heat exchange in the air heat exchanger 41 and closes the second expansion valve 32. Thus, the refrigerant does not flow through the heat source heat exchanger 42. Or the opening degree of the 2nd expansion valve 32 is made smaller than the case of the heating operation of normal operation mode, and the refrigerant | coolant amount which flows into the heat-source heat exchanger 42 is decreased. In this case, the heat of the heat source (heated water in the hot water state) of the heat source heat exchanger 42 is not actively transmitted to the air heat exchanger 41. For this reason, the heat transfer amount per unit time from the heat source heat exchanger 42 to the air heat exchanger 41 can be considerably reduced as compared with the heating operation in the normal operation mode.

  In this case, the heat source in the evaporation process basically depends on the air heat exchanger 41. For this reason, if frosting occurs on the surface of the air heat exchanger 41, the heat exchange efficiency in the air heat exchanger 41 is lowered. Therefore, the refrigerant evaporation process in the air heat exchanger 41 is impaired, the refrigerant evaporation amount is reduced, and the refrigerant pressure in the air heat exchanger 41 is gradually reduced. In this case, the evaporation temperature in the air heat exchanger 41, that is, the temperature T2 detected by the heat exchange temperature sensor 52 gradually decreases. Here, since it is estimated that the air temperature T1 basically does not fluctuate, the temperature difference ΔT between the air temperature T1 and the temperature T2 of the heat exchange temperature sensor 52 (evaporation temperature in the air heat exchanger 41) increases.

  When frost forms on the surface of the air heat exchanger 41 as described above, the temperature difference ΔT described above increases due to the operation of the second expansion valve 32 in the valve closing direction. For this reason, it is well detected by the control unit 6 based on ΔT that frost formation has occurred on the surface of the air heat exchanger 41. In this way, while performing the heating operation in the normal operation mode, if the frosting determination mode is performed periodically or irregularly and the temperature difference ΔT is obtained, the surface of the air heat exchanger 41 is based on the magnitude of ΔT. The presence or absence of frost formation in is detected. Here, if the magnitude of ΔT is equal to or greater than a predetermined value, it is determined that frost is formed on the surface of the air heat exchanger 41. If the magnitude of ΔT is less than the predetermined value, it is determined that frost is not formed on the surface of the air heat exchanger 41. When frost formation on the air heat exchanger 41 is detected, it is preferable to appropriately perform a defrosting (defrost) process for reducing or eliminating frost on the surface of the air heat exchanger 41.

  In addition, when the rotation speed of the compressor 1 decreases and the refrigerant circulation amount in the refrigeration cycle apparatus is relatively small, ΔT tends to be small. For this reason, even if frost is formed on the surface of the air heat exchanger 41, frost formation tends to be difficult to detect. Therefore, according to the present embodiment, the relationship between the refrigerant circulation amount per unit time in the refrigeration cycle apparatus and the magnitude of ΔT for determining the presence or absence of frost formation is determined in a predetermined area of the memory 60 mounted in the control unit 6. Can be stored. In the frosting determination mode, the refrigerant circulation amount per unit time in the refrigeration cycle apparatus is obtained, and the magnitude of a predetermined value related to ΔT that determines the presence or absence of frosting is determined according to the obtained refrigerant circulation amount. The control unit 6 can be set.

  FIG. 2 and FIG. 3 show data of test examples performed on actual machines. The horizontal axis of FIG. 2 indicates time (relative display), and the vertical axis indicates temperature (relative display). The change in the air temperature T1 is shown as a characteristic line T10. The evaporation temperature T2 of the air heat exchanger 41 is shown as a characteristic line T20. From time t0 to time t1, the first expansion valve 31 and the second expansion valve 32 are opened, and the heating operation in the normal operation mode in which the condensation heat exchanger 2 releases the heat of condensation is performed. In this case, the temperature T2 of the air heat exchanger 41 is relatively high from time t0 to time t1 because it is affected by the heat of the heated water in the heated water passage 43 flowing through the heat source heat exchanger 42. It becomes. The frost determination mode A is performed from time t1 to time t2. In the frosting determination mode A, the first expansion valve 31 is opened at time t1, but the second expansion valve 32 is switched from the open state to the closed state. In the frosting determination mode A, since the second expansion valve 32 is closed, the refrigerant basically does not flow to the heat source heat exchanger 42. For this reason, the refrigerant of the air heat exchanger 41 is not easily affected by the heat of the heated water (heat source) in the hot water state flowing through the heat source heat exchanger 42. Therefore, the temperature T2 of the air heat exchanger 41 is relatively lowered between time t1 and time t2. However, since the surface of the air heat exchanger 41 is not yet frosted, it can be said that the temperature difference ΔTa (ΔTa = T1−T2) shown in FIG. 2 is small.

  From time t2 to time t3, the frost determination mode A is completed, and the heating operation in the normal operation mode is performed. Therefore, the 1st expansion valve 31 and the 2nd expansion valve 32 are opened, and the heating operation which discharge | releases condensation heat with the heat exchanger 2 for condensation is implemented. The surface of the air heat exchanger 41 was frosted between time t2 and time t3. At time t3, the first expansion valve 31 is opened, but the second expansion valve 32 is closed. That is, the frosting determination mode B is performed from time t3 to time t4. In the frosting determination mode B, the second expansion valve 32 is closed as described above, and basically the refrigerant does not flow to the heat source heat exchanger 42. For this reason, the air heat exchanger 41 is not easily affected by the heat of the heated water (heat source) in the hot water state flowing through the heat source heat exchanger 42. For this reason, between the time t3 and the time t4, as shown as the characteristic line T20, the temperature T2 of the air heat exchanger 41 is relatively lowered. In this case, ΔTb (ΔTb = T1−T2) in the frost determination mode B is larger than ΔTa in the frost determination mode A (ΔTb> ΔTa). Thus, according to this test example, when the surface of the air heat exchanger 41 is not frosted, ΔT (ΔT = T1−T2) is detected by the control unit 6 as being small. Thereby, frost formation is detected. On the other hand, when the surface of the air heat exchanger 41 is frosted, ΔTb, that is, ΔT (ΔT = T1-T2) is detected by the control unit 6 as being large.

  The horizontal axis of FIG. 3 indicates time (relative display), and the vertical axis indicates temperature (relative display) and refrigerant pressure (relative display). In FIG. 3, the characteristic line P <b> 1 indicates the pressure of the high-pressure refrigerant on the discharge port 1 o side of the compressor 1. A characteristic line P2 indicates the pressure of the low-pressure refrigerant on the suction port 1s side of the compressor 1. A characteristic line T40 indicates the temperature (blowing temperature) T4 of the air from the heat exchanger 2 for condensation. As can be understood from FIG. 3, even if the frosting determination modes A and B are performed during the heating operation, the temperature of the air from the heat exchanger 2 for condensation changes so much as shown by the characteristic line T40. There is no. That is, even if the frost determination modes A and B are performed during the heating operation, it means that the decrease in the heating operation capability can be suppressed.

  In the present embodiment, the following form may be adopted.

(I) The above-described determination of the temperature difference ΔT is made after a set time has elapsed since the start of the frost determination mode. Examples of the set time include 3 minutes, 5 minutes, and 7 minutes. The set time is preferably 1 to 10 minutes, more preferably 2 to 7 minutes and 3 to 5 minutes. If the set time is too short, the temperature difference is too small and the determination accuracy is lowered. If the set time is too long, the stop time in the normal operation mode becomes long, which is not preferable for heating operation.

(Ii) The above-described measurement of the temperature difference ΔT can also be performed when the evaporation temperature of the air heat exchanger 41 is stabilized. When the evaporation temperature is stabilized, for example, the temperature change amount is measured every set time (for example, 10 seconds), and the temperature change amount per minute is within ± 1 ° C. The measurement time interval for both temperatures is much shorter than the set time (for example, 0.1 second).

(Iii) Instead of determining by the temperature difference ΔT between the air temperature and the evaporation temperature of the air heat exchanger 41, the evaporating temperature of the air heat exchanger 41 at the start of the frost determination mode and the set time elapse from the start of the frost determination mode. You may determine by the temperature difference with the evaporation temperature of the air heat exchanger 41 after. In this case, the above (i) and (ii) are similarly applied.

(Iv) Instead of determining by the temperature difference ΔT between the air temperature and the evaporation temperature of the air heat exchanger 41, the temperature difference ΔTo between the air temperature at the start of the frosting determination mode and the evaporation temperature of the air heat exchanger 41 is obtained, The temperature difference ΔT between the air temperature and the evaporation temperature of the air heat exchanger after the set time has elapsed from the start of the frosting determination mode is determined, and it is determined whether or not the ratio (ΔT / ΔTo) between the two is greater than the set value. Also good. For example, if the ratio is greater than 2, the control unit 6 determines that frost formation has occurred. In this case, the above (i) and (ii) are similarly applied.

(V) Instead of determining by the temperature difference ΔT between the air temperature and the evaporation temperature of the air heat exchanger 41, the presence or absence of frost is determined by the rate of change of the evaporation temperature of the air heat exchanger 41 at the start of the frost determination mode. You may do it. For example, if the rate of change is greater than 2 ° C./min, it is determined that frost formation has occurred. This rate of change can be the rate of change from the start of the frost determination mode until the set time has elapsed. As the set time, it can be performed in a shorter time (for example, 1 minute) than the determination by the temperature difference.

  FIG. 4 shows a third embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. As shown in FIG. 4, a bypass passage 71 that connects the discharge port 1 o of the compressor 1 and the inlet side of the air heat exchanger 41 is provided so as to bypass the condensation heat exchanger 2. A bypass valve 72 is provided in the bypass passage 71. The bypass valve 72 may be a variable valve whose opening is variable continuously or stepwise, or may be an on / off valve whose opening is switched to 100% or 0%. When performing the heating operation in the normal operation mode, the bypass valve 72 is closed. Therefore, the high-temperature and high-pressure refrigerant compressed by the compressor 1 is not supplied to the air heat exchanger 41 through the bypass passage 71. In contrast, after it is determined that frost is present in the frost determination mode, the control unit 6 performs the defrost mode for a set time. When carrying out the defrosting mode, the controller 6 opens the opening of the bypass valve 72. The opening degree may be 100% or a slight opening degree. Therefore, the high-temperature and high-pressure gaseous refrigerant compressed by the compressor 1 is supplied toward the inlet 41 i side of the air heat exchanger 41 through the bypass passage 71 and the bypass valve 72. As a result, the high-temperature and high-pressure gaseous refrigerant that has been compressed by the compressor 1 and passed through the bypass passage 7 is merged with the refrigerant that has completed the condensation process in the condensation heat exchanger 2 at the junction 9e. As a result, the refrigerant that has finished the condensing step is supplied to the inlet 41i of the air heat exchanger 41 in a heated state. Thereby, the frost frosting on the surface of the air heat exchanger 41 is reduced or removed. When the defrosting is completed, the bypass valve 72 is closed.

FIG. 5 shows a control mode A of the fourth embodiment. FIG. 5 shows a flowchart of a control form A executed by the CPU 61 of the control unit 6. Y corresponds to YES. N corresponds to NO. As shown in FIG. 6, first, the controller 6 performs heating operation in the normal operation mode when the power is turned on (step S2). The controller 6 determines whether or not a set time β1 (for example, 30 minutes) has elapsed since the start of the heating operation, whether or not the set time β1 has elapsed since the end of the defrosting mode, It is determined whether or not a set time β1 (for example, 30 minutes) has elapsed since the end of (no frost) (step S4). If the set time β1 has elapsed (YES in step S4), the control unit 6 performs a frost determination mode (step S6). The frost determination mode, the control unit 6, while opening the first expansion valve 31, or closing the second expansion valve 32, as well as much smaller than the opening degree of the opening degree of heating the normal mode, the air temperature sensor The air temperature T1 detected at 51 and the temperature T2 detected by the heat exchanger temperature sensor 52 are read. A temperature difference ΔT between T1 and T2 is obtained. Next, it is determined whether or not ΔT is higher than a threshold temperature α1 (for example, 7 ° C.) (step S8). If the temperature difference ΔT is larger than the threshold temperature α1 (for example, 7 ° C.), the control unit 6 estimates that the surface of the air heat exchanger 41 is frosted, and the control unit 6 executes the defrosting mode. (Step S10). When the defrosting mode ends, the process returns to step S4. If ΔT (ΔT = T1−T2) is equal to or lower than a threshold temperature α1 (for example, 7 ° C.), it is estimated that the surface of the air heat exchanger 41 is not frosted, and the control unit 6 executes the defrosting mode. Without returning to step S4. Step S8 functions as frost formation determination means.

  FIG. 6 shows a control mode B of the fourth embodiment. FIG. 6 shows a flowchart of a control mode B executed by the CPU 61 of the control unit 6. As shown in FIG. 6, first, the controller 6 performs heating operation in the normal operation mode when the power is turned on (step SB2). The controller 6 determines whether or not a set time β1 (for example, 30 minutes) has elapsed since the start of the heating operation, whether or not the set time β1 has elapsed since the end of the defrosting mode, It is determined whether or not a set time β1 (for example, 30 minutes) has elapsed since the end of (no frost) (step SB4). If setting time (beta) 1 has passed, the control part 6 will implement frosting determination mode (step SB6). In the frosting determination mode, the controller 6 closes the second expansion valve 32 while opening the first expansion valve 31, or makes the opening degree considerably smaller than the opening degree in the heating operation in the heating normal mode. . If the number of times that the frosting determination mode is executed is counted and the number of continuous executions of the frosting determination mode is less than the threshold number η1 (NO in step SB8), the surface of the air heat exchanger 41 is frosted. Since it is estimated that it is not, the control part 6 does not perform defrost mode, but returns to step SB4. However, if the number of continuous executions in the frosting determination mode is equal to or greater than the threshold number η1 (YES in step SB8), it is estimated that there is a high possibility of frosting on the surface of the air heat exchanger 41. Unit 6 executes the defrosting mode (step SB10). If defrost mode is complete | finished, the control part 6 will return to step SB4. Here, when the defrost mode is executed, the count number of the continuous execution times of the frost determination mode is reset (reset even if the frost determination is performed in the frost determination mode and the defrost mode is executed). . The reason for performing this control is to reliably perform defrosting even if frost formation is missed in the frost determination mode (for example, there is a possibility that a frost determination error may occur in the case of insufficient refrigerant).

  FIG. 7 shows a control mode C of the fourth embodiment. FIG. 7 shows a flowchart of a control mode C executed by the CPU 61 of the control unit 6. As shown in FIG. 7, first, the controller 6 performs heating operation in the normal operation mode when the power is turned on (step SC2). The controller 6 determines whether or not a set time β1 (for example, 30 minutes) has elapsed since the start of the heating operation, whether or not the set time β1 has elapsed since the end of the defrosting mode, It is determined whether or not a set time β1 (for example, 30 minutes) has elapsed since the end of (no frost) (step S4B). If setting time (beta) 1 has passed, the control part 6 will implement frost formation determination mode (step SC6). In the frosting determination mode, the control unit 6 opens the first expansion valve 31 and closes the second expansion valve 32 or makes the opening degree considerably smaller than the opening degree in the heating normal mode. Further, the supply valve 44v of the heating water circuit 43 is closed (step SC7). In some cases, the opening of the supply valve 44v is made smaller than in the heating operation in the normal operation mode. This further suppresses the heat of the heating water (heat source) of the heat generation source 45 such as the engine from being transmitted to the air heat exchanger 41.

  Furthermore, in the frosting determination mode described above, the air temperature T1 and the temperature T2 of the heat exchange temperature sensor 52 are read. If ΔT, which is T1-T2, is equal to or lower than a threshold temperature α1 (eg, 7 ° C.) (NO in step SC8), the supply valve is used to continue the heating operation in the normal operation mode without executing the defrost mode. The supply valve 44v is opened so that the opening degree of 44v returns to the opening degree of the heating operation in the normal operation mode (step SC12), and the process returns to step SC4. On the other hand, if ΔT is larger than the threshold temperature α1 (for example, 7 ° C.) (YES in step SC8), it is estimated that the surface of the air heat exchanger 41 is frosted, and the control unit 6 removes it. The frost mode is executed (step SC10). According to the control mode C, the supply valve 44v is closed in step SC7 and the supply valve 44v is opened in step SC12. However, the present invention is not limited to this. In step SC7, the opening degree of the supply valve 44v is maintained. The water flow rate of the pump 44p in the heating water passage 43 may be zero or reduced. In step SC12, the water flow rate of the pump 44p is returned to the water flow rate of the heating operation in the normal operation mode.

  FIG. 8 shows a fifth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. The heat source heat exchanger 42 has a heated water passage 46 a through which hot water generated in the hot water storage tank of the fuel cell system 46 flows. The heat of the hot water flowing through the heating water passage 46a functions as a heat source that promotes evaporation of the refrigerant in the heat source heat exchanger 42. The heated water passage 46a is provided with a hot water supply valve 47v and a pump 47p. According to the heating operation in the normal operation mode, the hot water supply valve 47v is opened and the pump 47p is driven to supply hot water to the heat source heat exchanger 42, thereby promoting the vaporization of the refrigerant in the heat source heat exchanger 42. According to the frosting determination mode, the hot water supply valve 47v is closed and the pump 47p is turned off. Alternatively, the opening degree of the hot water supply valve 47v and the rotational speed per unit time of the pump 47p are reduced as compared with the heating operation in the normal operation mode. Thereby, heat transfer from the heat source heat exchanger 42 to the air heat exchanger 41 is suppressed in the frost determination mode. As described above, when the heat transfer to the air heat exchanger 41 is suppressed, ΔT increases and the detection accuracy of frost increases.

  FIG. 9 shows a sixth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. The heat source heat exchanger 42 has a heater 48. The heat of the heater 48 functions as a heat source that promotes evaporation of the refrigerant in the heat source heat exchanger 42. According to the heating operation in the normal operation mode, the heater 48 generates heat, and the vaporization of the refrigerant in the heat source heat exchanger 42 is promoted. According to the frosting determination mode, the heater 48 is turned off or the amount of heat generated by the heater 48 is reduced as compared with the heating operation in the normal operation mode. Thereby, heat transfer from the heat source heat exchanger 42 to the air heat exchanger 41 is suppressed in the frost determination mode.

  Example 7 will be described with reference to FIG. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. In carrying out the frosting determination mode for determining whether or not the surface of the air heat exchanger 41 is frosted, the second expansion valve 32 is opened while the first expansion valve 31 shown in FIG. 1 is opened. Close or lower the degree. In this case, the refrigerant flow rate per unit time flowing through the heat source heat exchanger 42 is stopped or reduced as compared with the normal operation mode (normal heating operation). In this case, the refrigerant circulation amount in the refrigeration cycle apparatus may be reduced. As a result, the flow rate per unit time of the refrigerant flowing through the evaporating heat exchanger 4 is decreased, and the evaporation amount in the evaporating heat exchanger 4 performing the evaporating process may be greatly decreased. In this case, when carrying out the frost determination mode, the heating capacity of the refrigeration cycle apparatus may be reduced.

  Therefore, according to the present embodiment, the control unit 6 implements the first control mode. According to the first control mode, in the frost determination mode, the opening degree of the second expansion valve 32 is closed or reduced while basically maintaining the rotational speed of the compressor 1, and the air heat exchanger 41. The opening degree of the first expansion valve 31 connected to is increased as compared with the heating operation in the normal operation mode. Thereby, the refrigerant | coolant flow rate per unit time which flows through the air heat exchanger 41 in frost formation determination mode increases from the case of the heating operation in normal operation mode. Here, the refrigerant flow rate per unit time flowing through the air heat exchanger 41 can be increased by, for example, about 3 to 60% or about 5 to 30%, compared to the heating operation in the normal operation mode. As a result, the flow rate per unit time of the refrigerant flowing through the air heat exchanger 41 of the evaporation heat exchanger 4 that performs the evaporation step is ensured. Therefore, the evaporation amount in the evaporation heat exchanger 4 that performs the evaporation process is secured. In this case, a decrease in the amount of condensation heat released from the condensation heat exchanger 2 that performs the condensation step is suppressed. Therefore, a decrease in the heating capacity of the refrigeration cycle apparatus is suppressed while the frost determination mode is performed.

  Example 8 will be described with reference to FIG. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. In carrying out the frosting determination mode for determining whether or not the surface of the air heat exchanger 41 is frosted, the opening degree of the second expansion valve 32 is closed or reduced. In this case, the refrigerant flow rate per unit time flowing through the heat source heat exchanger 42 is stopped or reduced as compared with the normal operation mode (normal heating operation). In this case, the refrigerant circulation amount in the refrigeration cycle apparatus may be reduced. As a result, the flow rate per unit time of the refrigerant flowing through the heat exchanger for condensation 2 may be reduced. In this case, the amount of heat released per unit time of the heat of condensation from the heat exchanger 2 for condensing that performs the condensing step may be reduced, and the heating capacity of the refrigeration cycle apparatus may be reduced.

  As described above, in the frost determination mode, the refrigerant circulation amount in the refrigeration cycle apparatus may decrease. Therefore, according to the present embodiment, the control unit 6 implements the second control mode. According to the second control mode, in the frost determination mode, the control unit 6 determines the number of revolutions per unit time of the compressor 1 in the case of the heating operation in the normal operation mode when there is remaining capacity of the compressor 1. Also increase. The number of rotations per unit time of the compressor 1 can be increased by, for example, about 3 to 60% and about 5 to 30%, compared to the heating operation in the normal operation mode. In this case, the refrigerant circulation amount in the refrigeration cycle apparatus is ensured, and a decrease in the heating capacity of the refrigeration cycle apparatus is suppressed. When the compressor 1 is driven by an engine, the fuel supply amount and intake air amount per unit time to the engine are increased.

  FIG. 10 shows a ninth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. A common expansion valve 49 is provided as a three-way valve that also functions as the first expansion valve and the second expansion valve. In the common expansion valve 49, the port 49 f is connected to the condensation heat exchanger 2, the port 49 s is connected to the air heat exchanger 41, and the port 49 t is connected to the heat source heat exchanger 42. In the frosting determination mode, by adjusting the opening degree of the common expansion valve 49, the opening degree connected to the heat source heat exchanger 42 is reduced as compared with the normal operation mode (normal heating operation), and the air heat exchanger The opening degree connected to 41 is increased as compared with the case of the normal operation mode (normal heating operation). As a result, the refrigerant flow rate per unit time flowing through the heat source heat exchanger 42 decreases, and the refrigerant flow rate per unit time flowing through the air heat exchanger 41 increases. As a result, the flow rate per unit time of the refrigerant flowing through the air heat exchanger 41 that performs the evaporation step is ensured. In this case, a decrease in the amount of condensation heat released from the condensation heat exchanger 2 that performs the condensation step is suppressed. Therefore, a decrease in the heating capacity of the refrigeration cycle apparatus is suppressed while the frost determination mode is performed.

  FIG. 11 shows a tenth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. In the frosting determination mode, if the opening degree of the second expansion valve 32 is reduced or set to 0, the flow rate of the refrigerant flowing through the heat source heat exchanger 42 per unit time is reduced as compared with that in the normal operation mode. Can do. Similarly, the flow rate per unit time of the refrigerant flowing through the air heat exchanger 41 can be increased as compared with the normal operation mode. Therefore, in the frosting determination mode, the amount of heat transferred per unit time from the heat source (hot water in the hot water flowing through the heating water passage 43) to the refrigerant in the heat source heat exchanger 42 should be reduced as compared with that in the normal operation mode. Can do. As a result, the temperature difference ΔT between the air temperature T1 and the temperature T2 of the heat exchanger temperature sensor 52 (evaporation temperature in the air heat exchanger 41) increases. As a result, the control unit 6 detects that frost formation has occurred on the surface of the air heat exchanger 41 based on ΔT. While performing the heating operation in the normal operation mode as described above, if the frosting determination mode is performed periodically or irregularly and the temperature difference ΔT is obtained, the surface of the air heat exchanger 41 is based on the temperature difference ΔT. The presence or absence of frost formation in is well detected. When frost formation is detected, it is preferable to appropriately perform a defrosting process for reducing or eliminating frost on the surface of the air heat exchanger 41.

  FIG. 12 shows Example 11. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. According to the data relating to this test example shown in FIG. 2, ΔT is small when the surface of the air heat exchanger 41 is not frosted. On the other hand, when the surface of the air heat exchanger 41 is frosted, ΔT is large. For this reason, the smaller the temperature difference ΔT, the smaller the degree of frost formation of the air heat exchanger 41. The greater the temperature difference ΔT, the greater the degree of frost formation. Therefore, according to the present embodiment, the control unit 6 obtains ΔT at intervals of time, and when detecting that ΔT is increasing in time, determines that frost is growing, and defrosts. Increase the time to execute the mode. Moreover, if frost formation has not grown, the time which implements defrost mode is shortened.

  FIG. 12 shows an example of a flowchart executed by the CPU 61 of the control unit 6. First, ΔT in the current frost determination mode is obtained (step SF2). This ΔT is stored in a predetermined area of the memory 60 of the control unit 6 (step SF4). ΔT in the previous frost determination mode is read from the memory 60 (step SF6). ΔT in the previous frost determination mode is compared with ΔT in the current frost determination mode, and the rate of change of ΔT is obtained (step SF8). It is determined whether the change rate of ΔT is higher than the threshold value ω. That is, it is determined whether or not ΔT is increased (step SF10). If the change rate of ΔT is equal to or greater than the threshold value ω, a command to the effect that frost has grown on the surface of the air heat exchanger 41 is output (step SF12). A command for increasing the time for performing the defrosting mode to be longer than the normal time is output (step SF14), and the process returns to the main routine.

  On the other hand, if the change rate of ΔT is less than the threshold value ω, a command indicating that frost has not grown so much on the surface of the air heat exchanger 41 is output (step SF22). And the command which makes time to implement defrost mode normal time (it shortens defrost mode implementation time rather than the case where frosting is growing) is outputted (Step SF24), and it returns to a main routine. In addition, it may replace with operation which increases the time which implements defrost mode, and may output the instruction | command which increases defrost capability. In order to increase the defrosting capacity, for example, in the case shown in FIG. 4, the opening degree of the bypass valve 72 is increased, and high-temperature and high-pressure gaseous refrigerant is supplied to the air heat exchanger 41 via the bypass valve 72. That's fine.

  FIG. 13 shows a twelfth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. The heat source heat exchanger 42 and the air heat exchanger 41 constituting the evaporation heat exchanger 4 are arranged in series. The heat source heat exchanger 42 is disposed upstream of the air heat exchanger 41 (on the condensation heat exchanger 2 side). A parallel flow path 42x is provided in parallel to the heat source heat exchanger 42 that functions as a bypass path that bypasses the heat source heat exchanger 42, and the first expansion valve 31 is provided in the parallel flow path 42x. In some cases, the first expansion valve 31 may be eliminated and replaced with a capillary. In the frost formation determination mode, the second expansion valve 32 may be closed or throttled.

  FIG. 14 shows a thirteenth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. In the following, different parts will be mainly described. The heat source heat exchanger 42 and the air heat exchanger 41 constituting the evaporation heat exchanger 4 are arranged in series. The heat source heat exchanger 42 is disposed closer to the compressor 1 than the air heat exchanger 41. A parallel flow path 42 y is provided in parallel with the heat source heat exchanger 42. The parallel flow path 42 y is a bypass passage that bypasses the heat source heat exchanger 42 and the second expansion valve 32. The first expansion valve 31 is disposed between the air heat exchanger 41 and the condensation heat exchanger 2. The second expansion valve 32 is disposed upstream of the heat source heat exchanger 42 (on the air heat exchanger 41 side). In the frosting determination mode, the supply valve 44v can be closed or the rotation speed of the pump 44p can be reduced. The upstream and downstream are premised on the heating operation. In the frost formation determination mode, the second expansion valve 32 may be closed or throttled. In some cases, the first expansion valve 31 may be eliminated and replaced with a capillary.

  FIG. 15 shows a fourteenth embodiment. This embodiment basically has the same configuration and operational effects as the first embodiment. FIG. 15 is a piping diagram of an air conditioner (gas engine heat pump) showing a typical example of a refrigeration cycle apparatus. The air conditioner includes a plurality of indoor units 80 that perform indoor air conditioning, and an outdoor unit 81 that adjusts a refrigerant that performs indoor air conditioning. As shown in FIG. 15, the indoor unit 80 is disposed indoors, and the indoor heat exchanger 2X that functions as a condensation heat exchanger that performs heat exchange between the refrigerant and the indoor air for air conditioning functions during heating operation. And an indoor expansion valve 116 for expanding the refrigerant as a basic element. The number of indoor units 80 may be any number.

  The outdoor unit 81 is arranged outdoors. The outdoor unit 81 includes an engine 100 (drive source) driven by gaseous fuel, an accumulator 101 that stores the refrigerant in a state where the gaseous refrigerant and the liquid refrigerant are separated, and an accumulator that is driven by the engine 100 and driven. A plurality of compressors 1 that sucks and compresses 101 gaseous refrigerant, an air heat exchanger 41 that functions as an outdoor heat exchanger that performs heat exchange of the refrigerant for air conditioning, and a heat source heat exchanger 42 As a basic element. The compressor 1 is interlocked by the engine 100 via a power transmission member 102 such as a timing belt. Therefore, the engine 100 functions as a drive source for the compressor 1. The compressor 1 has a suction port 1s that sucks gaseous refrigerant from the accumulator 101 into a compression chamber, and a discharge port 1o that discharges high-pressure gaseous refrigerant compressed in the compression chamber.

  As will be described later, in the return direction (arrow K1 direction) in which the refrigerant returns from the indoor unit 80 to the outdoor unit 81 during the heating operation, upstream of the air heat exchanger 41, the first expansion valve 31 as an electronic adjustment valve and A check valve 103 is arranged in parallel. The check valve 103 allows the flow of refrigerant from the air heat exchanger 41 of the outdoor unit 81 to the indoor unit 80, but blocks the flow of refrigerant from the indoor unit 80 to the air heat exchanger 41 of the outdoor unit 81. . The opening degree of the first expansion valve 31 can be adjusted continuously or in multiple stages by electrical control. A fan 41f that blows air toward the air heat exchanger 41 and a fan 2f that blows air toward the indoor heat exchanger 2X are provided.

  In the defrosting mode, the refrigerant discharged from the compressor 1 is sent to the oil separator 105 and the four-way valve 111. The refrigerant is sent from the first port 111 f of the four-way valve 111 to the air heat exchanger 41. The high temperature refrigerant sent to the air heat exchanger 41 melts frost that forms on the air heat exchanger 41 (the refrigerant condenses). A part of the refrigerant discharged from the air heat exchanger 41 mainly passes through the check valve 103 and is sent to the indoor heat exchanger 2X via the expansion valve 116, and partly passes through the second expansion valve 32. It is sent to the heat source heat exchanger 42 by the refrigerant flow path 9p. The fan 2f of the indoor heat exchanger 2X stops in order not to flow cool air into the room. At this time, there is a case where the expansion valve 116 is set to the maximum opening degree and a case where the expansion valve 116 is closed. In the former case, the refrigerant passes through the indoor heat exchanger 2X without being used as an expansion valve. In the latter case, the refrigerant is not sent to the indoor heat exchanger 2X. In any case, there is no heat transfer in the indoor heat exchanger 2X. The refrigerant discharged from the heat source heat exchanger 42 is sent to the actuator 101 through the refrigerant flow path 9w. When the refrigerant is sent to the indoor heat exchanger 2X, the refrigerant is sent to the actuator 101 via the refrigerant flow paths 9i and 9h, the four-way valve 111, and the refrigerant flow path 9w.

(During heating operation)
First, the case where the room is heated will be described. When the engine 100 is driven using fuel gas as fuel, the compressor 1 is driven, and the gaseous refrigerant in the accumulator 101 is sucked from the suction port 101s of the accumulator 101 and the suction port 1s of the compressor 1 through the flow path 9e and compressed. It is compressed in the compression chamber of the machine 1. The gaseous refrigerant compressed to high temperature and high pressure is discharged from the discharge port 1o of the compressor 1 and reaches the flow path 9f and the oil separator 105. As described above, oil is separated from the refrigerant in the oil separator 105. The gaseous high-temperature and high-pressure refrigerant from which the oil has been separated passes through the third port 111t of the four-way valve 111, passes through the flow path 9h, the valve 115b, and the flow path 9i to the indoor heat exchanger 2X that functions as a condenser. Finally, heat is exchanged with indoor air in the indoor heat exchanger 2X to condense (liquefy). Since the condensation heat is released into the room, the room is heated. Heating operation is performed in this way. During the heating operation, the refrigerant that has been liquefied through the indoor heat exchanger 2X enters a liquid phase state or a gas-liquid two phase state, reaches the indoor expansion valve 116, is expanded by the indoor expansion valve 116 of the indoor unit 80, and has a low pressure. Become. Further, the low-pressure refrigerant flows through the flow path 9k, the valve 115a, and the flow path 9m in the direction of the arrow K1 (in the direction of returning from the indoor unit 80 to the outdoor unit 81 during the heating operation) and flows to the first expansion valve 31. The pressure is expanded by the first expansion valve 31 to reduce the pressure, and the air heat exchanger 41 is reached. The refrigerant evaporates in the air heat exchanger 41 and exchanges heat with air. Therefore, the air heat exchanger 41 functions as an evaporator during the heating operation of the indoor unit 80.

  Further, the refrigerant returns to the return port 101r of the accumulator 101 through the flow path 9n, the first port 111f, the second port 111s, and the flow path 9w of the four-way valve 111. The returned refrigerant is stored in a state where it is separated into a liquid refrigerant and a gaseous refrigerant by the accumulator 101.

  As shown in FIG. 15, a heat source heat exchanger 42 is arranged in parallel with the air heat exchanger 41. Here, when the second expansion valve 32 is opened, the refrigerant flows to the heat source heat exchanger 42 via the flow path 9p. When the second expansion valve 32 is closed, the refrigerant does not flow to the heat source heat exchanger 42 via the flow path 9p. As shown in FIG. 15, a pump 44 p, an engine 100, a first valve 300, and a second valve 400 functioning as a conveyance source are provided in the heated water passage 43 connected to the heat source heat exchanger 42. When the temperature of the engine heating water in the heating water passage 43 that has cooled the engine 100 is low, the port 301 and the port 302 of the first valve 300 are communicated, but the port 303 is closed. In this case, heated water does not flow through the heat source heat exchanger 42 and the radiator 150. When the temperature of the heating water in the heating water passage 43 rises, the port 301 and the port 302 of the first valve 300 are communicated, but the port 301 and the port 303 of the first valve 300 are communicated. However, although the port 401 and the port 402 of the second valve 400 are communicated, the port 401 and the port 403 of the second valve 400 are not communicated. Accordingly, warm heated water flows through the flow path 42w of the heat source heat exchanger 42, but does not flow through the radiator 150 having a large heat release amount. The flow path 42w of the heat source heat exchanger 42 functions as a heat source for heating the refrigerant in the heat source heat exchanger 42. When the temperature of the heated water in the heated water passage 43 further increases, the port 401 and the port 402 of the second valve 400 are communicated, and the port 401 and the port 403 are communicated. Thus, warm heated water flows into the flow path 42w of the heat source heat exchanger 42, and also flows into the radiator 150 through the flow path 43r, and returns to the pump 44p side through the flow path 43t. Note that the radiator 150 is larger than the heat source heat exchanger 42 with respect to the heat exchange amount per unit time. Therefore, the heat radiation amount of the radiator 150 is made larger than that of the heat source heat exchanger 42. When the temperature of the heated water in the heated water passage 43 rises excessively, the pressure cap 151 on the radiator 150 side is opened and stored in the reservoir 152. When the temperature of the heated water cools again, the pressure cap 151 on the radiator 150 side is opened, and the heated water stored in the reservoir 152 returns to the radiator 150 side.

(When cooling indoor unit 80)
Next, a description will be given of a case where the indoor unit 80 performs a cooling operation in the room. When the engine 100 is driven using fuel gas as fuel, the compressor 1 is driven, and the gaseous refrigerant in the accumulator 101 is sucked from the suction port 101 s of the accumulator 101 and the suction port 1 s of the compressor 1, and the compression chamber of the compressor 1 is driven. It is compressed with. The gaseous refrigerant compressed to high temperature and high pressure is discharged from the discharge port 1o of the compressor 1 and reaches the flow path 9f and the oil separator 105. Oil is separated from the refrigerant in the oil separator 105. The high-temperature and high-pressure refrigerant from which the oil has been separated passes through the flow path 9u, the first port 111f of the four-way valve 111 as the flow path switching valve, and the flow path 9n, and reaches the air heat exchanger 41. The high-temperature and high-pressure refrigerant is heat-exchanged with air by the air heat exchanger 41 to be cooled and liquefied. The liquefied refrigerant (liquid phase state or gas-liquid two-phase state) reaches the indoor expansion valve 116 via the check valve 103, the flow path 9m, the valve 115a and the flow path 9k, and expands in the indoor expansion valve 116. It becomes low temperature.

  Furthermore, it reaches the indoor heat exchanger 2X, and heat is exchanged with indoor air in the indoor heat exchanger 2X to cool the room. Furthermore, the refrigerant returns to the return port 101r of the accumulator 101 through the flow path 9i, the valve 115b, the flow path 9h, the third port 111t of the four-way valve 111, the second port 111s of the four-way valve 111, and the flow path 9w. The refrigerant returned to the accumulator 101 is accommodated in a state where it is separated into a liquid refrigerant and a gaseous refrigerant by the accumulator 101.

(Other)
The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications without departing from the scope of the invention. Although one air heat exchanger 41 is mounted, a plurality of air heat exchangers 41 may be used. Although one heat source heat exchanger 42 is mounted, a plurality of heat source heat exchangers 42 may be used.

  The present invention can be used for a refrigeration cycle apparatus such as an air conditioner.

1 is a configuration diagram illustrating a concept of a refrigeration cycle apparatus according to Embodiment 1. FIG. 6 is a graph showing test data according to Example 2. 6 is a graph showing test data according to Example 2. It is a block diagram which concerns on Example 3 and shows the concept of a refrigerating-cycle apparatus. 10 is a flowchart according to control mode A executed by a control unit according to a fourth embodiment. 10 is a flowchart according to a control mode B executed by a control unit according to a fourth embodiment. 12 is a flowchart according to a control mode C executed by a control unit according to a fourth embodiment. FIG. 10 is a configuration diagram illustrating a concept of a refrigeration cycle apparatus according to a fifth embodiment. FIG. 10 is a configuration diagram illustrating a concept of a refrigeration cycle apparatus according to a sixth embodiment. It is a block diagram which shows the concept of a refrigeration cycle apparatus in connection with Example 9. It is a block diagram which concerns on Example 10 and shows the concept of a refrigerating-cycle apparatus. 18 is a flowchart executed by the control unit according to the eleventh embodiment. It is a block diagram which concerns on Example 12 and shows the concept of a refrigeration cycle apparatus. It is a block diagram which concerns on Example 13 and shows the concept of a refrigerating-cycle apparatus. It is a block diagram which concerns on Example 14 and shows the concept of an air conditioning apparatus. It is a block diagram which shows the concept of a refrigeration cycle apparatus concerning a prior art example. It is a block diagram which shows the concept of a refrigeration cycle apparatus concerning another prior art example.

  1 is a compressor, 2 is a heat exchanger for condensation, 3 is an expansion valve, 31 is a first expansion valve, 32 is a second expansion valve, 4 is a heat exchanger for evaporation, 41 is an air heat exchanger, 42 is a heat source A heat exchanger, 51 is an air temperature sensor, 52 is a heat exchange temperature sensor, and 6 is a control unit.

Claims (8)

A compressor that performs a compression process for compressing the refrigerant, a heat exchanger for condensation that performs a condensation process for condensing the refrigerant that has passed through the compressor, an expansion valve that expands the refrigerant that has undergone the condensation process, and the expansion valve In a refrigeration cycle apparatus comprising an evaporation heat exchanger that performs an evaporation step for evaporating a refrigerant, and a control unit that controls the expansion valve,
(I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with heat from the heat source,
(Ii) The control unit
(A) a normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger;
(B) The refrigerant having passed through the expansion valve is flowed to the air heat exchanger to perform heat exchange in the air heat exchanger, and the amount of heat transferred from the heat source heat exchanger to the refrigerant per unit time is set in the normal operation mode. performed and frost formation determination mode for performing an operation to reduce than the,
(Iii) The expansion valve is provided between the first expansion valve provided between the heat exchanger for condensation and the air heat exchanger, and between the heat exchanger for condensation and the heat source heat exchanger. A second expansion valve,
In the frosting determination mode, the control unit sets the opening of the second expansion valve connected to the heat source heat exchanger to 0, or sets the opening of the second expansion valve to be in the normal operation mode. A refrigeration cycle apparatus, characterized in that the refrigerant flow rate per unit time flowing toward the heat source heat exchanger is reduced to 0 or less than in the normal operation mode . In Claim 1, the said control part increases the opening degree of a said 1st expansion valve in the said frost determination mode rather than the case of the said normal operation mode, and per unit time which flows toward the said air heat exchanger. A refrigeration cycle apparatus, wherein the refrigerant flow rate is increased as compared with the normal operation mode. A compressor that performs a compression process for compressing the refrigerant, a heat exchanger for condensation that performs a condensation process for condensing the refrigerant that has passed through the compressor, an expansion valve that expands the refrigerant that has undergone the condensation process, and the expansion valve In a refrigeration cycle apparatus comprising an evaporation heat exchanger that performs an evaporation step for evaporating a refrigerant, and a control unit that controls the expansion valve,
  (I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with heat from the heat source,
  (Ii) The control unit
  (A) a normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger;
  (B) The refrigerant having passed through the expansion valve is flowed to the air heat exchanger to perform heat exchange in the air heat exchanger, and the amount of heat transferred from the heat source heat exchanger to the refrigerant per unit time is set in the normal operation mode. The frosting determination mode for performing the operation to reduce than in the case of
  (Iii) The expansion valve is a common expansion valve formed of a three-way valve including a port connected to the heat exchanger for condensation, a port connected to the air heat exchanger, and a port connected to the heat source heat exchanger,
  In the frosting determination mode, the control unit sets the opening of a port connected to the heat source heat exchanger in the common expansion valve to 0 or reduces the opening of the heat source heat than in the normal operation mode. A refrigeration cycle apparatus characterized in that the flow rate of refrigerant per unit time flowing toward the exchanger is reduced to 0 or less than in the normal operation mode. A compressor that performs a compression process for compressing the refrigerant, a heat exchanger for condensation that performs a condensation process for condensing the refrigerant that has passed through the compressor, an expansion valve that expands the refrigerant that has undergone the condensation process, and the expansion valve In a refrigeration cycle apparatus comprising an evaporation heat exchanger that performs an evaporation step for evaporating a refrigerant, and a control unit that controls the expansion valve,
  (I) The evaporation heat exchanger that performs the evaporation step includes an air heat exchanger that exchanges heat with air, and a heat source heat exchanger that exchanges heat with heat from the heat source,
  (Ii) The control unit
  (A) a normal operation mode in which heat exchange is performed in the air heat exchanger and the heat source heat exchanger by flowing the refrigerant that has passed through the expansion valve to the air heat exchanger and the heat source heat exchanger;
  (B) The refrigerant having passed through the expansion valve is flowed to the air heat exchanger to perform heat exchange in the air heat exchanger, and the amount of heat transferred from the heat source heat exchanger to the refrigerant per unit time is set in the normal operation mode. The frosting determination mode for performing the operation to reduce than in the case of
  (Iii) The expansion valve is provided between the heat exchanger for condensation, the air heat exchanger, and the heat source heat exchanger,
  In the frost determination mode, the control unit adjusts the opening of the expansion valve connected to the heat source heat exchanger, thereby reducing the refrigerant flow rate per unit time flowing toward the heat source heat exchanger to 0 or A refrigeration cycle apparatus characterized in that the refrigeration cycle device is reduced as compared with a normal operation mode. 5. The refrigerant control unit according to claim 1, wherein the control unit sets the refrigerant flow rate per unit time flowing toward the heat source heat exchanger in the frosting determination mode to 0 or in the normal operation mode. A refrigeration cycle apparatus that decreases and increases the flow rate of refrigerant per unit time that flows toward the air heat exchanger as compared to the normal operation mode. In one of the claims 1-5, wherein, in the frost determination mode, wherein the increase than the rotational speed per unit of compressor time of the normal operation mode Refrigeration cycle equipment. In one of claims 1 to 6, wherein, in the frost determination mode, can the temperature difference between the evaporation temperature of the air heat exchanger and the air temperature is increasing temporally , has a determining frost growth determination unit frost is grown, when it is determined that the frost is growing, the control unit is characterized by increasing during the defrosting frozen Cycle equipment. 8. The bypass according to claim 1, wherein a bypass passage connecting a discharge port of the compressor and an inlet of the air heat exchanger is provided to bypass the condenser heat exchanger. There is a bypass valve in the passage,
  When the controller determines that frost is present in the frost determination mode, the controller opens the opening of the bypass valve, and causes the refrigerant compressed by the compressor to pass through the bypass passage and the bypass valve. A refrigeration cycle apparatus that reduces or removes frost forming on the air heat exchanger by supplying the air heat exchanger to an inlet side of the air heat exchanger.

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