Refrigeration cycle device

Abstract

To provide a refrigeration cycle device capable of suppressing deterioration of heating capacity when a heat storage heat exchanger is provided and a heat storage operation is performed.SOLUTION: A refrigeration cycle device includes: a refrigerant circuit C having a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4 that exchanges heat between a thermal storage medium and a refrigerant, a heat storage side expansion valve 51 and an indoor side expansion valve 53; and a control device 7 that controls the heat storage side expansion valve 51 and the indoor side expansion valve 53. The control device 7 performs control for switching between a heating operation in which closing of the heat storage side expansion valve 51 causes the refrigerant to flow into the indoor heat exchanger 2 and a heat storage heating operation in which opening of the heat storage side expansion valve 51 causes part of the refrigerant to flow into the heat storage heat exchanger 4. The control device performs control for narrowing an opening of the indoor side expansion valve 53 during switching from the heating operation to the heat storage heating operation, and performs control for opening the opening of the indoor side expansion valve 53 during switching from the heat storage heating operation to the heating operation.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a refrigeration cycle device. [Background technology]

[0002] Generally, when an air conditioner is in heating operation, a low-temperature refrigerant flows through the outdoor heat exchanger. Therefore, for example, when the outdoor air temperature is below freezing, if the refrigerant temperature falls below the dew point of the outdoor air, frost will form on the outdoor heat exchanger, making it difficult to exchange heat with the outdoor air. Therefore, when the air conditioner is in heating operation, a defrosting operation is periodically performed to remove frost from the outdoor heat exchanger.

[0003] Such defrosting operation is necessary for operating an air conditioner, and is typically performed by interrupting heating operation. Specifically, when starting defrosting operation, the refrigerant circuit is switched so that the refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger, causing the outdoor heat exchanger to function as a condenser to melt the frost and perform defrosting. During defrosting operation, the high-temperature refrigerant supplied to the outdoor heat exchanger for defrosting is cooled by melting the frost, and the low-temperature refrigerant flows into the indoor heat exchanger.

[0004] When such a defrosting operation is performed, the heating operation is stopped and the indoor temperature gradually drops during the defrosting operation, which reduces user comfort. Therefore, as shown in Patent Document 1 below, for example, a heat storage device is provided in the refrigeration circuit separately from the indoor heat exchanger, and heat is stored in the heat storage device during heating operation (hereinafter, such an operating mode will be referred to as "heat storage heating operation" as appropriate).

[0005] One possible method is to use the heat stored in the heat storage device for defrosting during defrosting, thereby continuing heating operation even during defrosting. This method prevents a drop in the indoor temperature due to the temporary suspension of heating operation for defrosting, thereby maintaining user comfort. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-017738 Summary of the Invention [Problem to be solved by the invention]

[0007] In heating operation, all of the refrigerant discharged from the compressor is supplied to the indoor heat exchanger. However, when switching from heating operation to heat storage heating operation, a portion of the refrigerant discharged from the compressor, which was previously supplied entirely to the indoor heat exchanger, is now supplied to the heat storage device. The amount of refrigerant supplied to the heat storage device depends on the settings, but in any case, the amount of refrigerant supplied to the indoor heat exchanger is reduced compared to heating operation.

[0008] An expansion valve (hereinafter, referred to as the "indoor expansion valve") is provided downstream of the indoor heat exchanger in the direction of refrigerant flow during heating operation. During heating operation, the opening of the indoor expansion valve is adjusted, for example, by feedback control, so that the intake superheat of the compressor reaches an appropriate target value. However, if the opening of the indoor expansion valve is not appropriate, this may result in a decrease in heating capacity and a decrease in compressor reliability.

[0009] This will be explained by taking as an example a case where the opening of the indoor expansion valve is larger than the appropriate opening, for example, when the amount of refrigerant supplied to the indoor heat exchanger is reduced by switching from heating operation to heat storage heating operation, but the opening of the indoor expansion valve remains at the opening that corresponds to the amount of refrigerant supplied to the indoor heat exchanger during heating operation.

[0010] In this case, the amount of pressure reduction by the indoor expansion valve for the refrigerant flowing out of the indoor heat exchanger decreases, causing the condensing temperature in the indoor heat exchanger to decrease and the evaporating temperature in the outdoor heat exchanger to increase, resulting in a decrease in the heating capacity of the indoor heat exchanger.

[0011] Furthermore, the amount of refrigerant flowing into the outdoor heat exchanger (evaporator) becomes excessive and the refrigerant becomes slightly wet, which causes the compressor's intake superheat to decrease, resulting in a liquid compression state in the compressor, which increases bearing loads and reduces reliability.

[0012] On the other hand, in contrast to when the opening degree of such an indoor expansion valve is larger than the appropriate opening degree, even when the opening degree of the indoor expansion valve is smaller than the appropriate opening degree, this can similarly result in a decrease in heating capacity and a decrease in compressor reliability.

[0013] This can occur, for example, when switching from heat storage heating operation to heating operation, in which the opening of the indoor expansion valve remains at the opening that corresponds to the amount of refrigerant supplied to the indoor heat exchanger during heat storage heating operation, even though the supply of refrigerant to the heat storage device is stopped and the amount of refrigerant supplied to the indoor heat exchanger increases.

[0014] In this case, the indoor expansion valve reduces the pressure of the refrigerant flowing out of the indoor heat exchanger, causing the condensing temperature in the indoor heat exchanger to rise and the evaporating temperature in the outdoor heat exchanger to fall. If the condensing temperature rises, the heating operation may be stopped to prevent compressor failure due to increased bearing load, etc. As a result, the heating capacity of the indoor heat exchanger decreases.

[0015] On the other hand, if a drop in the evaporation temperature of the outdoor heat exchanger occurs, the air conditioner cannot distinguish this from a drop in evaporation temperature due to frost formation on the outdoor heat exchanger. As a result, the air conditioner may erroneously determine that frost has formed on the outdoor heat exchanger. If this occurs, the air conditioner will temporarily stop heating operation and start defrosting operation, as described above, resulting in a decrease in heating capacity.

[0016] In addition, the amount of refrigerant flowing into the outdoor heat exchanger (evaporator) decreases, causing a refrigerant shortage, which in turn causes the compressor's suction superheat to increase. As a result, the suction density of the refrigerant decreases, causing the compressor to overheat, which may lead to a protective shutdown of the heating operation to avoid breakdowns.

[0017] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a refrigeration cycle device that can suppress a decrease in heating capacity when a heat storage heat exchanger is installed and heat storage operation is performed. [Means for solving the problem]

[0018] A refrigeration cycle device according to one aspect of the present invention includes a compressor that compresses a refrigerant, an indoor heat exchanger that exchanges heat between the refrigerant and indoor air, an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, a heat storage heat exchanger that exchanges heat between a heat storage material and the refrigerant, a heat storage side expansion valve provided in a heat storage circuit in which the heat storage heat exchanger is arranged, and an indoor expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger, and a control device that controls the heat storage side expansion valve and the indoor expansion valve, and the control device controls switching between a heating operation in which the refrigerant discharged from the compressor flows into the indoor heat exchanger by closing the heat storage side expansion valve, and a heat storage heating operation in which a portion of the refrigerant discharged from the compressor flows into the heat storage heat exchanger by opening the heat storage side expansion valve, and controls to reduce the opening of the indoor expansion valve when switching from heating operation to heat storage heating operation, and controls to increase the opening of the indoor expansion valve when switching from heat storage heating operation to heating operation. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a refrigeration cycle apparatus that is provided with a heat storage heat exchanger and is capable of suppressing a decrease in heating capacity when a heat storage operation is performed. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a refrigerant circuit diagram of a refrigeration cycle device according to an embodiment of the present invention. [Figure 2] 1 is a refrigerant circuit diagram showing the flow of refrigerant when a refrigeration cycle device according to an embodiment of the present invention performs cooling operation. [Figure 3] 1 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle device according to an embodiment of the present invention performs heating operation. [Figure 4] 3 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle device according to the embodiment of the present invention performs a heat storage heating operation. FIG. [Figure 5] 1 is a block diagram showing an internal configuration of a control device in a refrigeration cycle apparatus according to an embodiment of the present invention. [Figure 6] 4 is a flowchart showing a control flow when the operating mode is changed between heating operation and heat-storage heating operation in the refrigeration cycle device according to the embodiment of the present invention. [Figure 7] 10 is a flowchart showing a flow of adjusting the opening degrees of the heat-storage-side expansion valve and the indoor-side expansion valve when the refrigeration cycle apparatus according to the embodiment of the present invention shifts from heating operation to heat-storage heating operation. [Figure 8] 10 is a flowchart showing a flow of adjusting the opening degrees of the heat-storage-side expansion valve and the indoor-side expansion valve when the refrigeration cycle device according to the embodiment of the present invention shifts from a heat-storage heating operation to a heating operation. DETAILED DESCRIPTION OF THE INVENTION

[0021] The structure of a refrigeration cycle apparatus S according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus S according to the embodiment of the present invention. The refrigeration cycle apparatus S includes a refrigerant circuit C that connects a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4, an expansion valve 5 (51, 52, 53), and a switching valve 6 (61, 62) and circulates a refrigerant. The refrigeration cycle apparatus S also includes a control device 7 that controls the expansion valve 5 and the switching valve 6.

[0022] Here, a refrigerant circuit C of a refrigeration cycle apparatus S according to an embodiment of the present invention will be described with reference to Fig. 1. The refrigerant circuit C is composed of each device such as the compressor 1 described above and flow paths through which a refrigerant flows that connect these devices.

[0023] The compressor 1 compresses the refrigerant circulating through the refrigerant circuit C. The indoor heat exchanger 2 exchanges heat between the indoor air and the refrigerant. The outdoor heat exchanger 3 exchanges heat between the outdoor air and the refrigerant. Although a detailed description of the types of the compressor 1, indoor heat exchanger 2, and outdoor heat exchanger 3 will be omitted here, various types of equipment can be used.

[0024] The refrigeration cycle apparatus S according to the embodiment of the present invention is provided with a discharge temperature sensor 11 that detects the temperature of the refrigerant discharged from the compressor 1. The discharge temperature of the refrigerant detected by the discharge temperature sensor 11 is used, for example, in control during heating operation, which will be described later.

[0025] The indoor heat exchanger 2 is equipped with a room temperature sensor 21 that detects the temperature of the room, and a temperature sensor that detects the temperature of the refrigerant in the indoor heat exchanger 2. As will be described later, the operating mode of the refrigeration cycle apparatus S in this embodiment of the present invention will be mainly described in the case of heating operation or heat storage heating operation. Therefore, hereinafter, this temperature sensor will be referred to as a "condensation temperature sensor 22" that detects the condensation temperature especially in heating operation, etc.

[0026] The outdoor heat exchanger 3 is also equipped with an outdoor air temperature sensor 31 that detects the outdoor air temperature, and a temperature sensor that detects the temperature of the refrigerant in the outdoor heat exchanger 3. As described above, the operating mode of the refrigeration cycle apparatus S in the embodiment of the present invention will be mainly described in the case of heating operation or heat storage heating operation. Therefore, the temperature sensor will be referred to hereinafter as an "evaporation temperature sensor 32" that detects the evaporation temperature particularly in heating operation, etc.

[0027] The thermal storage heat exchanger 4 is a heat exchanger that exchanges heat between a thermal storage material and a refrigerant that passes through the thermal storage heat exchanger 4. The thermal storage heat exchanger 4 is, for example, a fin-and-tube type heat exchanger. The thermal storage heat exchanger 4 is disposed, for example, in a thermal storage container filled with a thermal storage material.

[0028] The heat storage material may be liquid or solid, as long as it can store heat by exchanging heat with the refrigerant flowing inside the heat storage heat exchanger 4. Therefore, for example, the heat storage heat exchanger 4 is surrounded by a heat storage material. This heat storage material stores heat supplied from the refrigerant, and the stored heat is used, for example, to remove frost that has adhered to the outdoor unit, as will be described later.

[0029] The heat storage heat exchanger 4 is also provided with a heat storage temperature sensor HS that detects the heat storage temperature, which is the temperature of the heat storage heat exchanger 4. Therefore, the heat storage temperature sensor HS detects the temperature of the heat storage material present inside the heat storage heat exchanger 4.

[0030] The heat storage temperature sensor HS may be only one or may be multiple. When multiple heat storage temperature sensors HS are provided, the detected temperature of the heat storage material may be calculated, for example, by taking the average value of the values ​​detected by the respective heat storage temperature sensors HS as the temperature of the heat storage material, and used for control, which will be described later.

[0031] The opening degree of the expansion valve 5 can be adjusted based on instructions from a control device 7, which will be described later, and a plurality of expansion valves are provided in the refrigeration cycle apparatus S in the embodiment of the present invention. Specifically, three expansion valves are provided, and the thermal storage side expansion valve 51 is provided upstream in the direction of refrigerant flow when the thermal storage heat exchanger 4 functions as a condenser, i.e., when thermal storage heating operation is performed.

[0032] A heat-storage-side downstream expansion valve 52 is provided between the heat-storage heat exchanger 4 and the above-mentioned junction C1 in the refrigerant circuit C. That is, it is provided downstream in the direction in which the refrigerant flows when the heat-storage heat exchanger 4 functions as a condenser.

[0033] As described above, the refrigeration cycle apparatus S in the embodiment of the present invention is provided with the heat storage heat exchanger 4. Heat is stored in the heat storage heat exchanger 4 by causing the refrigerant discharged from the compressor 1 to flow into the heat storage heat exchanger 4. Therefore, hereinafter, the circuit from the heat storage side expansion valve 51 to the heat storage heat exchanger 4 and the junction C1 will be referred to as the heat storage circuit C2 as appropriate.

[0034] Therefore, in the flow direction of the refrigerant when the refrigerant discharged from the compressor 1 flows into the heat-storage heat exchanger 4, the heat-storage-side expansion valve 51 is provided upstream of the heat-storage circuit C2. On the other hand, the heat-storage-side downstream expansion valve 52 is provided downstream of the heat-storage circuit C2.

[0035] The indoor expansion valve 53 is provided in a flow path connecting the indoor heat exchanger 2 and the outdoor heat exchanger 3. In other words, it is provided downstream in the direction in which the refrigerant flows when the indoor heat exchanger 2 functions as a condenser.

[0036] The switching valve 6 is composed of a first switching valve 61 and a second switching valve 62. The first switching valve 61 is provided between the compressor 1 and the indoor heat exchanger 2. The second switching valve 62 is provided between the compressor 1 and the outdoor heat exchanger 3 or the thermal storage heat exchanger 4.

[0037] The first switching valve 61 is controlled by a control device 7, which will be described later, to switch between flowing the refrigerant discharged from the compressor 1 to the indoor heat exchanger 2 and flowing the refrigerant to a bypass circuit B connected to a flow path between the heat-storage-side expansion valve 51 and the second switching valve 62. On the other hand, the second switching valve 62 switches between flowing the refrigerant discharged from the compressor 1 to the heat-storage heat exchanger 4 and flowing the refrigerant to the outdoor heat exchanger 3.

[0038] The bypass circuit B is provided between the first switching valve 61 and the second switching valve 62. The bypass circuit B is provided with a check valve or the like so that the refrigerant flows only in the direction of the arrow as shown in FIG.

[0039] When the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2, the bypass circuit B is connected to the suction side of the compressor 1. On the other hand, when the refrigerant discharged from the compressor 1 flows into the bypass circuit B that connects to the flow path between the heat-storage-side expansion valve 51 and the second switching valve 62, the indoor heat exchanger 2 is connected to the suction side of the compressor 1.

[0040] The second switching valve 62 is controlled by the control device 7 to switch between flowing the refrigerant discharged from the compressor 1 to the heat-storage heat exchanger 4 and flowing it to the outdoor heat exchanger 3. When the refrigerant discharged from the compressor 1 flows to the heat-storage heat exchanger 4, the outdoor heat exchanger 3 and the suction side of the compressor 1 are connected. On the other hand, when the refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3, the heat-storage heat exchanger 4 and the suction side of the compressor 1 are connected.

[0041] In the following, when these three expansion valves, the heat-storage-side expansion valve 51, the heat-storage-side downstream expansion valve 52, and the indoor-side expansion valve 53, are collectively described, they will be referred to as "expansion valve 5," and when each expansion valve is described individually, they will be referred to by their respective names. Similarly, when these two switching valves 61 and 62 are collectively described, they will be referred to as "switching valve 6," and when each switching valve is described individually, they will be referred to by their respective names.

[0042] Furthermore, in the refrigeration cycle device S according to the embodiment of the present invention, the heating operation is not stopped even when the heat storage operation is performed on the heat storage heat exchanger 4, and a heat storage heating operation is performed in parallel with the heat storage operation.

[0043] The control device 7 controls the opening degrees of the plurality of expansion valves 5. The control device 7 controls the opening degrees of each expansion valve, thereby adjusting the flow rate of the refrigerant flowing through the refrigerant circuit C. As described above, the control device 7 switches the flow of the refrigerant circulating through the refrigerant circuit C by switching the plurality of switching valves 6.

[0044] By controlling the multiple expansion valves 5 and the multiple switching valves 6 in this way, the control device 7 performs, for example, a heating and heat storage operation in which heating operation and heat storage operation are performed in parallel. Also, when the operation mode is switched between heating operation and heat storage heating operation, for example, the control device 7 controls the opening degrees of the multiple expansion valves 5. The function of the control device 7 will be described later.

[0045] Next, the operating modes performed in the refrigeration cycle apparatus S according to the embodiment of the present invention will be described in order with reference to the circuit diagrams of the refrigeration cycle apparatus S according to the embodiment of the present invention shown in FIGS.

[0046] 2 to 4, refrigerant circuits C through which refrigerant actually flows are indicated by solid lines. On the other hand, refrigerant circuits C through which refrigerant does not flow are indicated by dashed lines. The direction of the refrigerant flowing in the refrigerant circuit C is indicated by arrows.

[0047] First, the cooling operation will be described. Fig. 2 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs cooling operation. During cooling operation, the indoor heat exchanger 2 functions as an evaporator, and the outdoor heat exchanger 3 functions as a condenser.

[0048] That is, the refrigerant compressed by the compressor 1 and discharged in a high-temperature, high-pressure state flows into the outdoor heat exchanger 3 via the thermal storage side expansion valve 51 and the second switching valve 62, as shown by the arrows in Fig. 2. At this time, the thermal storage side expansion valve 51 is fully open. The refrigerant discharged from the compressor 1 also flows through the first switching valve 61, but also passes through the bypass circuit B and flows into the outdoor heat exchanger 3 from the second switching valve 62.

[0049] The refrigerant that has flowed into the outdoor heat exchanger 3 is cooled by outdoor air that is supplied by the rotation of an outdoor fan (not shown), and dissipates heat into the outdoor air, causing a part or all of the refrigerant to condense.

[0050] The refrigerant that has released heat to the outside air in this way flows out of the outdoor heat exchanger 3 and passes through the indoor expansion valve 53, where it is decompressed to become a low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant then flows into the indoor heat exchanger 2, where it exchanges heat with the indoor air.

[0051] The refrigerant absorbs heat from the indoor air through heat exchange in the indoor heat exchanger 2 and evaporates, and the indoor air drawn into the indoor heat exchanger 2 is cooled and supplied to the room by an indoor fan (not shown), thereby cooling the room. The refrigerant that has absorbed heat through heat exchange then flows into the compressor 1 through the first switching valve 61.

[0052] Therefore, when cooling operation is performed, no refrigerant flows into the heat-storage heat exchanger 4. That is, the second switching valve 62 is switched so that the refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3. Therefore, the refrigerant discharged from the compressor 1 and passed through the heat-storage-side expansion valve 51 does not flow into the heat-storage circuit C2, nor does it flow into the heat-storage heat exchanger 4. In this case, the opening of the heat-storage-side downstream expansion valve 52 is adjusted to a preset opening.

[0053] Next, a description will be given of the flow of refrigerant when the refrigeration cycle apparatus S performs heating operation. Fig. 3 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs heating operation.

[0054] 3, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. Therefore, the refrigerant flowing to the indoor heat exchanger 2 side does not flow from the first switching valve 61 to the outdoor heat exchanger 3 via the bypass circuit B as in the cooling operation described above.

[0055] In the indoor heat exchanger 2, heat is exchanged between the refrigerant and the air flowing into the indoor unit, and the indoor heat exchanger 2 supplies warmed air to the indoor space by absorbing heat from the refrigerant. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0056] The refrigerant flowing out of the indoor heat exchanger 2 is decompressed as it passes through the indoor expansion valve 53, becoming a low-temperature, low-pressure refrigerant, which then flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the compressor 1 via the second switching valve 62.

[0057] During heating operation, since there is no need to flow refrigerant into the heat-storage heat exchanger 4, the heat-storage-side expansion valve 51 is controlled to be fully closed to prevent the refrigerant discharged from the compressor 1 from flowing into the heat-storage heat exchanger 4. In addition, the second switching valve 62 is also switched so that the refrigerant flowing out from the outdoor heat exchanger 3 flows into the compressor 1 via the second switching valve 62, as will be described later.

[0058] Because the heat-storage-side expansion valve 51 is fully closed in this manner, the refrigerant discharged from the compressor 1 does not flow into the heat-storage heat exchanger 4, and all of the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2. Furthermore, because the refrigerant discharged from the compressor 1 does not flow into the heat-storage heat exchanger 4, no heat exchange occurs between the heat storage material and the refrigerant in the heat-storage heat exchanger 4. The heat-storage-side downstream expansion valve 52 is controlled to have a preset opening.

[0059] The flow of refrigerant when the refrigeration cycle apparatus S performs the heat storage heating operation is as shown in Fig. 4. Fig. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs the heat storage heating operation. The heat storage heating operation is an operation in which heat is stored in the heat storage heat exchanger 4 by opening the heat storage side expansion valve 51 during the heating operation and causing a portion of the refrigerant discharged from the compressor 1 to flow into the heat storage heat exchanger 4.

[0060] As shown in Figure 4, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. In the indoor heat exchanger 2, heat is exchanged between the refrigerant and the air flowing into the indoor unit, and the air that has been heated by absorbing heat from the refrigerant is supplied to the indoor space. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0061] The refrigerant flowing out of the indoor heat exchanger 2 passes through the indoor expansion valve 53 and flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the compressor 1 via the second switching valve 62.

[0062] As described above, the refrigeration cycle apparatus S in the embodiment of the present invention is provided with the heat storage heat exchanger 4 in addition to the indoor heat exchanger 2 and the outdoor heat exchanger 3. When the heat storage heating operation is performed, the refrigerant discharged from the compressor 1 not only flows into the indoor heat exchanger 2 as described above, but also branches before reaching the first switching valve 61 and flows into the heat storage heat exchanger 4 via the heat storage side expansion valve 51 and the second switching valve 62.

[0063] That is, most of the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2, but a portion of it also flows into the heat-storage heat exchanger 4. The amount of refrigerant that flows into the heat-storage heat exchanger 4 is set appropriately. Specifically, it is adjusted by the opening of the heat-storage-side expansion valve 51.

[0064] In the heat storage heat exchanger 4, the refrigerant that has flowed in exchanges heat with the heat storage material, and the heat of the refrigerant is stored in the heat storage material. The refrigerant that has flowed out of the heat storage heat exchanger 4 flows into the outdoor heat exchanger 3 via the heat storage-side downstream expansion valve 52, and then flows out of the outdoor heat exchanger 3 and into the compressor 1 via the second switching valve 62.

[0065] Next, a more detailed description will be given of the control contents by the control device 7. As described above, in the refrigeration cycle apparatus S according to the embodiment of the present invention, a heat storage heating operation is performed in which heat is stored in the heat storage heat exchanger 4 while the heating operation is continued so that the heat stored in the heat storage heat exchanger 4 can be used when removing frost adhering to the outdoor unit.

[0066] When the heating operation is performed, feedback control is executed. Specifically, the opening degree of the indoor expansion valve 53 is controlled so that the temperature of the refrigerant discharged from the compressor 1 becomes a target discharge temperature (target discharge temperature control).

[0067] When target discharge temperature control is executed, information such as condensation temperature, evaporation temperature, compressor rotation speed, and outside air temperature is required as parameters, and control is performed based on these parameters. The reason for target discharge temperature control during heating operation is to ensure that the refrigerant that flows out of the indoor heat exchanger 2 and finally flows into the compressor 1 is in an appropriate state (sufficiently in a gas phase).

[0068] When the operating mode shifts from heating operation, in which such control is performed, to heat-storage heating operation, as described above, part of the refrigerant flowing into the indoor heat exchanger 2 flows into the heat-storage heat exchanger 4. Therefore, the amount of refrigerant flowing into the indoor heat exchanger 2 is less than the amount of refrigerant flowing into the indoor heat exchanger 2 during heating operation.

[0069] At this time, the opening degree of the indoor expansion valve 53 is controlled to be an appropriate opening degree for heating operation based on the target discharge temperature control described above. However, as the amount of refrigerant flowing into the indoor heat exchanger 2 decreases when the operating mode shifts from heating operation to heat storage heating operation, it is necessary to control the opening degree of the indoor expansion valve 53 to be an appropriate opening degree for heat storage heating operation.

[0070] When the operation mode is switched from heating operation to heat storage heating operation, the opening degree of the indoor expansion valve 53 is controlled to be appropriate for heating operation. However, when heat storage heating operation is performed, the amount of refrigerant flowing into the indoor heat exchanger 2 decreases, so the opening degree of the indoor expansion valve 53 becomes too large for heat storage heating operation.

[0071] That is, if the opening degree of the indoor expansion valve 53 is not adjusted in this state, for example, the amount of pressure reduction by the indoor expansion valve 53 for the refrigerant flowing out from the indoor heat exchanger 2 will decrease. As a result, the condensing temperature in the indoor heat exchanger 2 will decrease, and the heating capacity of the indoor heat exchanger 2 will decrease.

[0072] Conversely, when the operation mode is shifted from the heat storage heating operation to the heating operation, the heating operation is started. By shifting the operation mode in this way, all of the refrigerant discharged from the compressor 1 that had been flowing into the heat storage heat exchanger 4 now flows into the indoor heat exchanger 2.

[0073] At this time, the indoor expansion valve 53 is controlled to an opening suitable for the heat storage heating operation, but if it is not adjusted to an opening suitable for the heating operation, for example, the amount of pressure reduction by the indoor expansion valve 53 for the refrigerant flowing out from the indoor heat exchanger 2 increases. As a result, the condensing temperature in the indoor heat exchanger 2 increases and the evaporating temperature in the outdoor heat exchanger 3 decreases. If the condensing temperature increases, there is a possibility that the heating operation will be stopped for protection purposes, and as a result, the heating capacity of the indoor heat exchanger 2 decreases.

[0074] Furthermore, as described above, since feedback control is performed in the control of the heating operation, even if the operation mode is switched between the heating operation and the heat storage heating operation, it is difficult to immediately adjust the opening of the indoor expansion valve 53 to a value suitable for each operation mode. If the adjustment of the opening of the indoor expansion valve 53 is delayed, the above-mentioned adverse effects may occur.

[0075] Therefore, in the refrigeration cycle apparatus S according to the embodiment of the present invention, when switching from heating operation to heat storage heating operation, the indoor expansion valve 53 is controlled to be narrowed. Conversely, when switching from heat storage heating operation to heating operation, the indoor expansion valve 53 is controlled to be widened.

[0076] 5 is a block diagram showing the internal configuration of the control device 7 in the refrigeration cycle apparatus S according to the embodiment of the present invention. The control device 7 includes a detection unit 71, a storage unit 72, a determination unit 73, and an expansion valve opening control unit 74.

[0077] The control device 7 may also have a configuration in which, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface are connected via a bus, which are not shown in Fig. 5. Furthermore, the input / output interface may be connected to the above-mentioned components as well as components such as a display unit, a communication control unit, or an input unit.

[0078] The detection unit 71 acquires information detected by various sensors provided in the refrigeration cycle device S, such as the discharge temperature sensor 11, the room temperature sensor 21, the condensation temperature sensor 22, the outside air temperature sensor 31, and the evaporation temperature sensor 32.

[0079] The storage unit 72 stores a determination program and the like that is used when the determination unit 73, which will be described later, executes a determination process. When the operating mode is switched between heating operation and heat-storage heating operation, the opening and closing of the heat-storage-side expansion valve 51 is controlled, and the opening of the indoor expansion valve 53 is also controlled. In this case, when controlling the opening of the indoor expansion valve 53, as will be described later, a method of control based on the inlet pressure or outlet pressure of the heat-storage-side expansion valve 51 can also be used.

[0080] For example, when these methods are adopted, the opening degree of the indoor expansion valve 53 is correlated with the inlet pressure or outlet pressure of the heat-storage-side expansion valve 51. The memory unit 72 stores the relationship between these pressures and the opening degree of the indoor expansion valve 53.

[0081] The determination unit 73 determines how to set the opening of the indoor expansion valve 53 when the operation mode switches between heating operation and heat storage heating operation. Furthermore, the expansion valve opening control unit 74 controls the opening of each expansion valve 53 based on the determination result by the determination unit 73.

[0082] Next, the function of each part of the control device 7 in the embodiment of the present invention will be described in more detail. First, the case where the operation mode is switched from heating operation to heat storage heating operation will be described as an example. Therefore, it is assumed that heating operation is first being performed.

[0083] While the heating operation is being performed, whether or not it is necessary to transition to the heat storage heating operation is determined by the determination unit 73. However, the determination unit 73 does not make this determination immediately after the heating operation starts, but rather, for example, the determination as to whether or not to transition to the heat storage heating operation is not made until the refrigeration cycle apparatus S is started and the heating operation is performed stably.

[0084] When the heating operation starts, all of the heat of the refrigerant is used to heat the room. Therefore, for a while after the heating operation starts, all of the refrigerant discharged from the compressor 1 is caused to flow into the indoor heat exchanger 2. Therefore, the expansion valve opening control unit 74 controls the thermal storage side expansion valve 51 so that it is fully closed.

[0085] On the other hand, for example, when the indoor temperature approaches the set temperature of the indoor unit and low-load operation is being performed, or when a predetermined time has elapsed, the judgment unit 73 judges whether or not heat storage heating operation is necessary.

[0086] The conditions under which the heat storage heating operation is required are set in advance, and the determination unit 73 determines whether or not the conditions are met. For example, the condition that "heat storage material temperature < outside air temperature + 20°C" is set as the condition under which the heat storage heating operation is required. This allows the heat storage heating operation to be performed when the amount of stored heat is insufficient.

[0087] If the determination unit 73 determines that the heat storage heating operation is not necessary, the heating operation continues. On the other hand, if the determination unit 73 determines that the heat storage heating operation is necessary, the operation mode shifts from the heating operation to the heat storage heating operation.

[0088] During heating operation, as explained with reference to Fig. 3, the entire amount of refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. Therefore, when heating operation is being performed, the refrigerant discharged from the compressor 1 does not flow into the heat storage heat exchanger 4.

[0089] The refrigerant discharged from the compressor 1 does not flow into the heat-storage heat exchanger 4 because the expansion valve opening control unit 74 controls the heat-storage-side expansion valve 51 to be fully closed. Note that the opening of the heat-storage-side downstream expansion valve 52 is, for example, slightly open, and the opening of the indoor expansion valve 53 is fully open.

[0090] When the operating mode is switched from heating operation to heat-storage heating operation, it is necessary to cause some of the refrigerant, which had previously flowed entirely into the indoor heat exchanger 2, to flow into the heat-storage heat exchanger 4. Therefore, in order to allow a preset amount of refrigerant to flow into the heat-storage heat exchanger 4, the expansion valve opening control unit 74 controls the heat-storage-side expansion valve 51, which is controlled to be fully closed in heating operation, to an opening that corresponds to the amount of refrigerant to be flowed into the heat-storage heat exchanger 4.

[0091] As described above, in the refrigeration cycle apparatus S according to the embodiment of the present invention, a heat-storage heating operation is performed in which, simultaneously with the heating operation, heat is stored in the heat-storage heat exchanger 4. The heat of the refrigerant discharged from the compressor 1 is stored in the heat-storage heat exchanger 4 in order to use it to remove frost that has formed on the outdoor heat exchanger 3.

[0092] Therefore, before the defrosting operation in the defrosting heating operation that is appropriately performed between the heat-storage heating operations, it is necessary to store heat to be used in the defrosting operation in the heat-storage heat exchanger 4. In other words, between successive defrosting operations, during the heating operation that is performed from the end of the previous defrosting operation to the start of the subsequent defrosting operation, it is necessary to store sufficient heat in the heat-storage heat exchanger 4 to be used in the subsequent defrosting operation.

[0093] Heat is stored in the heat storage heat exchanger 4 by controlling the refrigerant discharged from the compressor 1 during heat storage heating operation so that some of the refrigerant also flows into the heat storage heat exchanger 4, not just the indoor heat exchanger 2. Specifically, this is done by an expansion valve opening control unit 74, which will be described later, controlling the opening of the heat storage side expansion valve 51. The expansion valve opening control unit 74 controls the opening of the heat storage side expansion valve 51, thereby adjusting the rate at which heat is stored in the heat storage heat exchanger 4.

[0094] When adjusting the rate of heat storage in the heat storage heat exchanger 4, for example, a gradient expressed by the relationship between the time required for heat storage and the temperature of the heat storage material is set, and the opening of the heat storage side expansion valve 51 is adjusted so that heat can be stored in the heat storage heat exchanger 4 along the gradient. Note that the gradient is set using the temperature of the heat storage material detected by the heat storage temperature sensor HS, the condensation temperature of the refrigerant in the indoor heat exchanger 2 detected by the condensation temperature sensor 22, and the outside air temperature detected by the outside air temperature sensor 31.

[0095] In this way, by switching the operation mode from heating operation to heat-storage heating operation, the heat-storage-side expansion valve 51 is controlled to be in an open state. At the same time, the expansion valve opening control unit 74 controls to reduce the opening of the indoor expansion valve 53. When performing this control, the following method can be used to determine the opening.

[0096] The first method is to determine the opening degree of the indoor expansion valve 53 in relation to the opening degree of the thermal-storage-side expansion valve 51. That is, the expansion valve opening control unit 74 controls the indoor expansion valve 53 so that the opening degree change amount, which is the difference between before and after control, increases as the opening degree of the thermal-storage-side expansion valve 51 increases.

[0097] That is, the opening degree of the heat-storage-side expansion valve 51 is controlled to a fully closed state during heating operation, but when the operation shifts to heat-storage heating operation, it is set in the manner described above according to the amount of refrigerant to be flowed into the heat-storage heat exchanger 4. Therefore, the opening degree of the heat-storage-side expansion valve 51 is set in various ways, and the opening degree varies.

[0098] In response to this, the indoor expansion valve 53 is controlled to reduce its opening. The opening (initial opening) that serves as the reference for the opening of the indoor expansion valve 53 is the opening during heating operation. This initial opening is the "opening before control" described above. On the other hand, as the operating mode shifts from heating operation to heat storage heating operation, the amount of refrigerant flowing into the indoor heat exchanger 2 decreases. Therefore, the opening of the indoor expansion valve 53 is controlled to accommodate the reduced amount of refrigerant. This controlled opening is the "opening after control" described above.

[0099] The difference between the opening degree of the indoor expansion valve 53 before and after control is understood as the "opening degree change amount." In other words, the opening degree change amount can be said to be a value that corrects the initial opening degree. The opening degree of the indoor expansion valve 53 is controlled so that the opening degree change amount increases as the opening degree of the thermal storage side expansion valve 51 increases.

[0100] In other words, a large opening of the heat-storage-side expansion valve 51 means that an increased amount of refrigerant discharged from the compressor 1 flows into the heat-storage heat exchanger 4. In other words, an increase in the amount of refrigerant flowing into the heat-storage heat exchanger 4 reduces the amount of refrigerant flowing into the indoor heat exchanger 2. Therefore, to accommodate the decrease in the amount of refrigerant flowing into the indoor heat exchanger 2, if the opening of the heat-storage-side expansion valve 51 is large, the amount of change in opening of the indoor expansion valve 53 is increased, and if the opening of the heat-storage-side expansion valve 51 is small, the amount of change in opening of the indoor expansion valve 53 is reduced.

[0101] Next, as another method, a method can be adopted in which the determination unit 73 sets the opening degree of the indoor expansion valve 53 based on the inlet pressure or outlet pressure of the heat-storage-side expansion valve 51. When based on the inlet pressure, the indoor expansion valve 53 is controlled so that the greater the inlet pressure of the heat-storage-side expansion valve 51, the greater the change in opening degree.

[0102] The reason why the inlet pressure of the heat storage side expansion valve 51 is used here is that the higher the inlet pressure of the heat storage side expansion valve 51, the greater the amount of refrigerant passing through the heat storage side expansion valve 51, and the relatively smaller the amount of refrigerant flowing to the indoor heat exchanger 2.

[0103] The inlet pressure can be determined, for example, based on the condensation temperature of the refrigerant inside the indoor heat exchanger 2 detected by the condensation temperature sensor 22. Of course, it may also be determined by providing a pressure sensor that detects the inlet pressure of the thermal storage side expansion valve 51 or a pressure sensor that detects the pressure of the refrigerant discharged from the compressor 1.

[0104] On the other hand, when the outlet pressure of the thermal storage side expansion valve 51 is used, the opening change amount of the indoor expansion valve 53 is controlled to increase as the outlet pressure of the thermal storage side expansion valve 51 decreases. In other words, the amount of refrigerant passing through the thermal storage side expansion valve 51 is related to the difference between the inlet pressure and the outlet pressure. The reason why the outlet pressure of the thermal storage side expansion valve 51 is used is that if the inlet pressure of the thermal storage side expansion valve 51 does not change, the difference between the inlet pressure and the outlet pressure increases as the outlet pressure of the thermal storage side expansion valve decreases, and therefore the amount of refrigerant passing through the thermal storage side expansion valve 51 increases, and the amount of refrigerant flowing to the indoor heat exchanger decreases relatively.

[0105] The outlet pressure can be determined, for example, based on the temperature of the heat storage material detected by the heat storage temperature sensor HS. That is, the reason for storing heat in the heat storage heat exchanger 4 is to utilize the heat stored in the heat storage heat exchanger 4 when a defrosting operation is performed. Therefore, the heat storage capacity when storing heat in the heat storage heat exchanger 4 can be set based on the rate at which frost forms on the outdoor heat exchanger 3 in relation to the outside air temperature, humidity, etc.

[0106] When the heat storage capacity is set in this way, the temperature difference between the heat storage temperature and the outlet pressure temperature of the heat-storage-side expansion valve 51 remains approximately constant. Therefore, the outlet pressure can be determined from the temperature of the heat storage material detected by the heat storage temperature sensor HS.

[0107] In this way, the opening of the thermal storage side expansion valve 51, the inlet pressure of the thermal storage side expansion valve 51, or the outlet pressure can be used when setting the opening of the indoor side expansion valve 53. The determination unit 73 acquires various information required for the adopted method from the detection unit 71 or the storage unit 72, and adjusts the opening of the indoor side expansion valve 53 based on the acquired information.

[0108] The expansion valve opening control unit 74 controls the openings of the thermal storage side expansion valve 51 and the indoor side expansion valve 53 in accordance with instructions from the determination unit 73. It is most preferable that the timing of controlling the opening of the indoor side expansion valve 53 be, for example, simultaneous with the timing of controlling the opening of the thermal storage side expansion valve 51.

[0109] If the opening degree of the indoor expansion valve 53 is controlled at such timing, it is possible to respond even if the operating mode switches from heating operation to heat storage heating operation and the opening degree of the heat storage side expansion valve 51 is controlled, resulting in a decrease in the amount of refrigerant flowing into the indoor heat exchanger 2.

[0110] However, the timing of controlling the aperture of the indoor expansion valve 53 does not necessarily have to be simultaneous with the timing of controlling the heat-storage-side expansion valve 51. In other words, it is sufficient that the aperture of the indoor expansion valve 53 is adjusted between the time when the heat-storage-side expansion valve 51 is controlled to the open state and the time when a change appears in the condensing temperature of the indoor heat exchanger 2 detected by the condensing temperature sensor 22.

[0111] The opening of the thermal-storage-side downstream expansion valve 52 is controlled to a predetermined opening. Specifically, the expansion valve opening control unit 74 controls the opening so that the amount of refrigerant flowing into the thermal-storage heat exchanger 4 is less than the amount of refrigerant flowing into the indoor heat exchanger 2.

[0112] That is, the heat storage heating operation is performed by causing a portion of the refrigerant that flows into the indoor heat exchanger 2 during heating operation to flow into the heat storage heat exchanger 4. However, as described above, the heating operation continues even while heat is being stored in the heat storage heat exchanger 4. Therefore, even if a portion of the refrigerant is caused to flow into the heat storage heat exchanger 4 for heat storage, it is necessary to keep the heating operation to a level that does not cause discomfort to the user.

[0113] After the adjustment of the opening degrees of the heat-storage-side expansion valve 51 and the indoor-side expansion valve 53 is completed, the determination unit 73 continues to determine whether the heat-storage heating operation has ended as needed while the heat-storage heating operation is being performed. For example, the determination unit 73 determines whether the required heat has been stored in the heat-storage heat exchanger 4 based on the gradient used in the control of the heat-storage-side expansion valve 51 described above.

[0114] If the determination unit 73 determines that the planned heat storage in the heat storage heat exchanger 4 has not been completed, the heat storage heating operation continues. On the other hand, if the determination unit 73 determines that sufficient heat has been stored in the heat storage heat exchanger 4, it determines that the heat storage heating operation should be terminated, and switches the operation mode from the heat storage heating operation to the heating operation. In this case, the heat storage side expansion valve 51 is controlled so as to change from an open state to a fully closed state.

[0115] On the other hand, the opening degree of the indoor expansion valve 53 is set in accordance with the heating capacity required of the indoor heat exchanger 2 during heating operation. Therefore, the determination unit 73 obtains information on the required heating capacity from, for example, the indoor unit.

[0116] Then, based on the acquired information, the opening degree of the indoor expansion valve 53 is adjusted. The expansion valve opening control unit 74 controls the opening degree of the indoor expansion valve 53 based on the determination result of the determination unit 73. It is most preferable that the timing of controlling the opening degree of the indoor expansion valve 53 be simultaneous with the timing of controlling the opening degree of the heat-storage-side expansion valve 51, for example.

[0117] However, the timing of controlling the opening degree of the indoor expansion valve 53 does not necessarily have to be simultaneous with the timing of controlling the heat-storage-side expansion valve 51. In other words, it is sufficient that the opening degree of the indoor expansion valve 53 is adjusted between the time when the determining unit 73 determines that the heat-storage heating operation has ended and the time when the heat-storage-side expansion valve 51 is controlled to be fully closed.

[0118] [Operation] Next, the flow of control of the refrigeration cycle apparatus S by the control device 7 when the operation mode is switched between the heating operation and the heat-storage heating operation will be described with reference to Fig. 6 to Fig. 8. Fig. 6 is a flowchart showing the flow of control when the operation mode is changed between the heating operation and the heat-storage heating operation in the refrigeration cycle apparatus according to the embodiment of the present invention.

[0119] First, heating operation is started (ST1), and then the judgment unit 73 of the control device 7 judges whether or not heat storage heating operation is necessary to store heat in the heat storage heat exchanger 4, i.e., whether or not to switch the operating mode to heat storage heating operation (ST2).

[0120] As described above, after the heating operation is started, for example, the judgment unit 73 judges that a predetermined time has elapsed, and then a judgment is made as to whether or not to switch the operating mode to the heat storage heating operation.

[0121] The determination unit 73 determines whether the above-mentioned condition for starting the heat storage heating operation, for example, that the difference between the heat storage material temperature and the outside air temperature is less than a predetermined value, is met. As a result, if the determination unit 73 determines that the condition is not met (NO in ST2), the heating operation continues.

[0122] On the other hand, if the determination unit 73 determines that the condition is met (YES in ST2), the heating operation is switched to the heat-storage heating operation (ST3). Then, the expansion valve opening control unit 74 adjusts the opening of each expansion valve 5 based on an instruction from the determination unit 73 (ST4). Here, Fig. 7 is a flowchart showing the flow of adjusting the opening of the heat-storage-side expansion valve 51 and the indoor expansion valve 53 when the refrigeration cycle apparatus S according to the embodiment of the present invention shifts from the heating operation to the heat-storage heating operation.

[0123] The expansion valve opening control unit 74 controls the thermal-storage-side expansion valve 51 so that it changes from a fully closed state to an open state. In this case, the opening of the thermal-storage-side expansion valve 51 is set based on the method described above (ST41).

[0124] Next, the expansion valve opening control unit 74 sets the opening of the indoor expansion valve 53. As a general control content, as described above, when switching from heating operation to heat storage heating operation, control is performed to reduce the opening of the indoor expansion valve 53.

[0125] Therefore, the expansion valve opening control unit 74 acquires information from the detection unit 71 via the detection unit 71 that matches the method for setting the opening of the indoor expansion valve 53 (ST42), and adjusts the opening of the indoor expansion valve 53 based on the acquired information (ST43).

[0126] Specifically, for example, the opening degree of the thermal storage side expansion valve 51 is controlled so that the opening degree change amount, which is the difference between the opening degree before and after control of the indoor side expansion valve 53, increases. Alternatively, the opening degree change amount of the indoor side expansion valve 53 is determined using the inlet pressure or outlet pressure of the thermal storage side expansion valve 51.

[0127] When the inlet pressure of the heat-storage-side expansion valve 51 is used, the indoor expansion valve 53 is controlled so that the greater the inlet pressure of the refrigerant to the heat-storage-side expansion valve 51, the greater the change in opening degree, which is the difference between before and after control of the indoor expansion valve 53. On the other hand, when the outlet pressure of the heat-storage-side expansion valve 51 is used, the indoor expansion valve 53 is controlled so that the greater the outlet pressure of the refrigerant to the heat-storage-side expansion valve 51, the smaller the change in opening degree, which is the difference between before and after control of the indoor expansion valve 53.

[0128] The apertures of the heat-storage-side expansion valve 51 and the indoor expansion valve 53 are set as described above and controlled by the expansion valve aperture control unit 74. In this state, heat-storage heating operation is performed. As described above, the timing of controlling the aperture of the indoor expansion valve 53 is simultaneous with the control of the heat-storage-side expansion valve 51, or between the time when the heat-storage-side expansion valve 51 is controlled to the open state and the time when a change in the condensing temperature of the indoor heat exchanger 2 detected by the condensing temperature sensor 22 appears.

[0129] While the heat storage heating operation is being performed, the determination unit 73 determines whether or not a termination condition for the heat storage heating operation is satisfied (ST5). The termination condition is, for example, whether or not the amount of change per unit time in the temperature of the heat storage material detected by the heat storage temperature sensor HS is less than a predetermined value. The predetermined value is determined by testing or the like.

[0130] If the determination unit 73 determines whether the termination condition for the heat storage heating operation is satisfied and the condition is not satisfied (NO in ST5), the heat storage heating operation continues. On the other hand, if the determination unit 73 determines that the termination condition is satisfied (YES in ST5), the operation mode is switched from the heat storage heating operation to the heating operation (ST6).

[0131] When the operation mode is switched, the opening of each expansion valve 5 is adjusted (ST7). Fig. 8 is a flowchart showing the flow of adjusting the opening of the heat-storage-side expansion valve 51 and the indoor-side expansion valve 53 when the refrigeration cycle apparatus S according to the embodiment of the present invention shifts from the heat-storage heating operation to the heating operation.

[0132] As mentioned above, it is preferable that the timing of controlling the opening degree of the indoor expansion valve 53 is simultaneous with the control of the heat-storage-side expansion valve 51. Therefore, in the following explanation using Fig. 8, although the explanation is given in separate steps for the sake of convenience, the control of the opening degree of the indoor expansion valve 53 and the control of the heat-storage-side expansion valve 51 are always simultaneous.

[0133] The determination unit 73 instructs the expansion valve opening control unit 74 to change the heat-storage-side expansion valve 51 from an open state to a fully closed state (ST71). Next, the determination unit 73 sets the opening of the indoor expansion valve 53. As a general control content, as described above, when switching from heat-storage heating operation to heating operation, control is performed to increase the opening of the indoor expansion valve 53.

[0134] Therefore, the determination unit 73 acquires information on the heating capacity required in the indoor heat exchanger 2, for example, from the indoor unit (ST72), and adjusts the opening degree of the indoor expansion valve 53 based on the acquired information (ST73).

[0135] Specifically, for example, the opening degree of the thermal storage side expansion valve 51 is controlled so that the opening degree change amount, which is the difference between the opening degree before and after control of the indoor side expansion valve 53, increases. Alternatively, the opening degree change amount of the indoor side expansion valve 53 is determined using the inlet pressure or outlet pressure of the thermal storage side expansion valve 51.

[0136] When the inlet pressure of the heat-storage-side expansion valve 51 is used, the indoor expansion valve 53 is controlled so that the greater the inlet pressure of the refrigerant to the heat-storage-side expansion valve 51, the greater the change in opening degree, which is the difference between before and after control of the indoor expansion valve 53. On the other hand, when the outlet pressure of the heat-storage-side expansion valve 51 is used, the indoor expansion valve 53 is controlled so that the greater the outlet pressure of the refrigerant to the heat-storage-side expansion valve 51, the smaller the change in opening degree, which is the difference between before and after control of the indoor expansion valve 53.

[0137] The openings of the thermal-storage-side expansion valve 51 and the indoor-side expansion valve 53 are set as described above and controlled by the expansion valve opening control section 74. In this state, heating operation is performed.

[0138] However, as mentioned above, the opening degree of the indoor expansion valve 53 can be controlled by adjusting the opening degree of the indoor expansion valve 53 between the time when the judgment unit 73 determines that the heat storage heating operation has ended and the time when the heat storage side expansion valve 51 is controlled to be fully closed.

[0139] As described above, when switching the operating mode between heating operation and heat storage heating operation, when switching from heating operation to heat storage heating operation, the opening of the indoor expansion valve 53 is controlled to be narrowed, and when switching from heat storage heating operation to heating operation, the opening of the indoor expansion valve 53 is controlled to be widened.

[0140] In other words, when switching between the heating operation and the heat storage heating operation, the opening of the indoor expansion valve can be controlled to an opening appropriate for the flow rate in anticipation of changes in the amount of refrigerant flowing into the indoor heat exchanger. By performing such control, it is possible to provide a refrigeration cycle apparatus that can suppress a decrease in heating capacity when a heat storage heat exchanger is provided and heat storage operation is performed.

[0141] It should be noted that the present invention is not limited to the above-described embodiment, but is merely an example of the present invention. In the implementation stage, the components can be modified and embodied without departing from the spirit of the invention, and various changes and improvements can be made to the above-described embodiment. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiment.

[0142] For example, some components may be deleted from all of the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate, and such modified or improved forms may also be included in the present invention. Such embodiments and their modifications are included in the scope and spirit of the inventions, and are also included in the scope of the inventions and their equivalents as defined in the claims.

[0143] The techniques described in the embodiments of the present invention may also be configured as follows. (1) a compressor that compresses a refrigerant; an indoor heat exchanger that exchanges heat between indoor air and the refrigerant; an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant; a heat storage heat exchanger that exchanges heat between a heat storage material and the refrigerant; a heat storage side expansion valve provided in a heat storage circuit in which the heat storage heat exchanger is disposed; a refrigerant circuit including an indoor expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger; a control device that controls the heat storage side expansion valve and the indoor side expansion valve, The control device The heat storage side expansion valve is closed to cause the refrigerant discharged from the compressor to flow into the indoor heat exchanger, and the heat storage side expansion valve is opened to cause a portion of the refrigerant discharged from the compressor to flow into the heat storage heat exchanger. A refrigeration cycle device characterized in that when switching from the heating operation to the heat storage heating operation, control is performed to reduce the opening of the indoor expansion valve, and when switching from the heat storage heating operation to the heating operation, control is performed to increase the opening of the indoor expansion valve. (2) The control device The refrigeration cycle device described in (1) above is characterized in that when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening of the indoor expansion valve is controlled so that the larger the opening of the heat storage side expansion valve, the larger the opening change amount, which is the difference between before and after control of the indoor expansion valve. (3) The control device The refrigeration cycle device described in (1) above is characterized in that when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening degree of the indoor expansion valve is controlled so that the greater the inlet pressure of the heat storage side expansion valve, the greater the change in opening degree, which is the difference between before and after control of the indoor expansion valve. (4) The control device The refrigeration cycle device described in (1) above is characterized in that when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening degree of the indoor expansion valve is controlled so that the smaller the heat storage side expansion valve outlet pressure, the larger the opening change amount, which is the difference between before and after control of the indoor expansion valve. (5) The control device The refrigeration cycle device according to any one of (1) to (4) above, wherein the control of the opening degree of the indoor expansion valve is performed simultaneously with the control of the opening degree of the heat-storage-side expansion valve. (6) A refrigeration cycle device described in any one of (1) to (5) above, characterized in that the heat storage side expansion valve is provided upstream of the heat storage heat exchanger when the heat storage heating operation is performed. [Explanation of symbols]

[0144] REFRIGERATION VALVE 71... DETECTION UNIT 72... STORAGE UNIT 73... DETECTION UNIT 74... EXPANSION VALVE OPENING CONTROL UNIT 75... DETECTION UNIT 76... DETECTION UNIT 77... DETECTION UNIT 78... DETECTION UNIT 79... DETECTION UNIT 80... DETECTION UNIT 81... DETECTION UNIT 82... DETECTION UNIT 83... DETECTION UNIT 84... DETECTION UNIT 85... DETECTION UNIT 86... DETECTION UNIT 87... DETECTION UNIT 88... DETECTION UNIT 89... DETECTION UNIT 90... DETECTION UNIT 91... DETECTION UNIT 92... DETECTION UNIT 93... DETECTION UNIT 94... DETECTION UNIT 95... DETECTION UNIT 96... DETECTION UNIT 97... DETECTION UNIT 98... DETECTION UNIT 99... DETECTION UNIT 100... DETECTION UNIT 101... DETECTION UNIT 102... DETECTION UNIT 103... DETECTION UNIT 104... DETECTION UNIT 105... DETECTION UNIT 106... DETECTION UNIT 107... DETECTION UNIT 108... DETECTION UNIT 109... DETECTION UNIT 110... DETECTION UNIT 111... DETECTION UNIT 112... DETECTION UNIT 113... DETECTION UNIT 114... DETECTION UNIT 115... DETECTION UNIT 116... DETECTION UNIT 117... DETECTION UNIT 118... D

Claims

1. a compressor that compresses a refrigerant; an indoor heat exchanger that exchanges heat between indoor air and the refrigerant; an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant; a heat storage heat exchanger that exchanges heat between a heat storage material and the refrigerant; a heat storage side expansion valve provided in a heat storage circuit in which the heat storage heat exchanger is disposed; a refrigerant circuit including an indoor expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger; a control device that controls the heat storage side expansion valve and the indoor side expansion valve, The control device The heat storage side expansion valve is closed to cause the refrigerant discharged from the compressor to flow into the indoor heat exchanger, and the heat storage side expansion valve is opened to cause a portion of the refrigerant discharged from the compressor to flow into the heat storage heat exchanger. A refrigeration cycle device characterized in that when switching from the heating operation to the heat storage heating operation, control is performed to reduce the opening of the indoor expansion valve, and when switching from the heat storage heating operation to the heating operation, control is performed to increase the opening of the indoor expansion valve.

2. The control device 2. The refrigeration cycle device according to claim 1, wherein when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening degree of the indoor expansion valve is controlled so that the larger the opening degree of the heat storage side expansion valve, the larger the opening change amount, which is the difference between the opening degree of the indoor expansion valve before and after control.

3. The control device 2. The refrigeration cycle device according to claim 1, wherein when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening degree of the indoor expansion valve is controlled so that the greater the inlet pressure of the heat storage side expansion valve, the greater the opening change amount, which is the difference between before and after control of the indoor expansion valve.

4. The control device 2. The refrigeration cycle device according to claim 1, wherein when switching from the heat storage heating operation to the heating operation, or when switching from the heating operation to the heat storage heating operation, the opening degree of the indoor expansion valve is controlled so that the smaller the outlet pressure of the heat storage side expansion valve, the larger the opening change amount, which is the difference between before and after control of the indoor expansion valve.

5. The control device 5. The refrigeration cycle apparatus according to claim 1, wherein the control of the opening degree of the indoor expansion valve is performed simultaneously with the control of the opening degree of the heat-storage expansion valve.

6. 2. The refrigeration cycle apparatus according to claim 1, wherein the heat-storage-side expansion valve is provided upstream of the heat-storage heat exchanger when the heat-storage heating operation is performed.

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