Refrigeration cycle device and method for controlling refrigeration cycle device

Abstract

Provided is a refrigeration cycle device having a heat storage heat exchanger in which, even when a cooling operation is performed, a refrigerant is prevented from staying inside the heat storage heat exchanger to minimize a reduction in the amount of the refrigerant circulating in a refrigerant circuit, thereby suppressing a decrease in capacity of the refrigeration cycle device. The refrigeration cycle device includes an indoor heat exchanger (2), an outdoor heat exchanger (3), a heat storage heat exchanger (4), a switching valve (6), and a control device (7) that controls the switching valve (6). The switching valve (6) switches a flow path between a cooling operation in which the outdoor heat exchanger (3) is caused to function as a condenser and the indoor heat exchanger (2) is caused to function as an evaporator, and a heat storage cooling operation in which at least the indoor heat exchanger (2) is caused to function as an evaporator when the heat storage heat exchanger (4) is caused to function as a condenser. The control device (7) controls the switching valve (6) so as to switch from the cooling operation to the heat storage cooling operation when a detection value of a heat storage temperature sensor (HS) that detects the temperature of a heat storage material during the cooling operation is lower than a first predetermined temperature.

Description

Refrigeration cycle device and control method for refrigeration cycle device

[0001] FIELD An embodiment of the present invention relates to a refrigeration cycle device and a control method for a refrigeration cycle device.

[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 refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger. In other words, defrosting is performed by making the outdoor heat exchanger function as a condenser. In defrosting operation, the high-temperature refrigerant supplied to the outdoor heat exchanger for defrosting melts 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, thereby reducing user comfort. Therefore, a method can be considered, such as that described in the following Patent Document 1, in which a heat storage tank (heat storage device) is provided in the refrigerant circuit separately from the indoor heat exchanger, and the heat stored in the heat storage material of the heat storage device is used for defrosting during the defrosting operation, thereby allowing the heating operation to continue even during the defrosting operation. This method prevents the indoor temperature from dropping due to the temporary stop of the heating operation for the defrosting operation, thereby maintaining user comfort.

[0005] When a heat storage device is installed in the refrigerant circuit and cooling operation is performed, the refrigerant discharged from the compressor is condensed in the outdoor heat exchanger and then flows into the indoor heat exchanger via an expansion valve. The indoor heat exchanger functions as an evaporator, exchanging heat between the refrigerant and the indoor air to supply cool air to the room. The refrigerant then flows into the compressor.

[0006] In this cooling operation, there is no need to exchange heat between the refrigerant and the heat storage material in the heat storage device, so the expansion valve provided between the outdoor heat exchanger and the heat storage device is closed to prevent the refrigerant from flowing into the heat storage device.

[0007] JP 2016-017738 A

[0008] When cooling is performed in this way, the expansion valve is closed to prevent refrigerant from flowing into the heat storage device. However, because the expansion valve is designed to allow a small amount of refrigerant to flow even when fully closed, the flow of refrigerant cannot be completely blocked. In other words, even during cooling operation, a small amount of refrigerant flows from the outdoor heat exchanger into the heat storage device through the closed expansion valve.

[0009] In many cases, heat storage devices are installed outdoors. When the heat storage material is cooled by outside air, the refrigerant flowing into the heat storage device condenses into a liquid phase. This means that the liquid phase refrigerant accumulates inside the heat storage device. Furthermore, the density of the liquid phase refrigerant is high, reducing the amount of refrigerant circulating through the refrigerant circuit. This reduction in the amount of refrigerant circulating through the refrigerant circuit can lead to a reduction in the capacity of the refrigeration cycle device.

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a refrigeration cycle device and a control method for a refrigeration cycle device that can prevent a decrease in the capacity of the refrigeration cycle device by preventing refrigerant from stagnating inside the heat storage heat exchanger and minimizing a decrease in the amount of refrigerant circulating through the refrigerant circuit, even when air conditioning operation is performed in the refrigeration cycle device equipped with a heat storage heat exchanger.

[0011] 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 the refrigerant and a heat storage material, a refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches the flow path when the refrigerant circulates, a heat storage temperature sensor that detects the temperature of the heat storage material, and a control device that controls the switching valve and the expansion valve. The switching valve switches the flow path between a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, and a heat storage cooling operation in which at least the indoor heat exchanger functions as an evaporator when the heat storage heat exchanger functions as a condenser. When the control device determines that the detection value of the heat storage temperature sensor has fallen below a first predetermined temperature during the cooling operation, the control device controls the switching valve to switch from the cooling operation to the heat storage cooling operation.

[0012] In addition, 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 the refrigerant and a heat storage material, a refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches the flow path when the refrigerant circulates, a heat storage temperature sensor that detects the temperature of the heat storage material, and a control device that controls the switching valve and the expansion valve.When the control device determines that the detection value of the heat storage temperature sensor has become lower than a first predetermined temperature during cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, the control device opens a second expansion valve arranged between the outdoor heat exchanger and the heat storage heat exchanger, and controls the refrigerant flowing out of the outdoor heat exchanger to flow into the heat storage heat exchanger.

[0013] A control method for a refrigeration cycle device according to one aspect of the present invention is a refrigeration cycle device including 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates, a heat storage temperature sensor that detects the temperature of the heat storage material, and a control device that controls the switching valve and the expansion valve, the method including the steps of: performing cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator; comparing the detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation by the control device; and, when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, controlling the switching valve by the control device to switch from the cooling operation to heat storage cooling operation in which at least the indoor heat exchanger functions as an evaporator when the heat storage heat exchanger functions as a condenser.

[0014] A control method for a refrigeration cycle device according to one aspect of the present invention is a refrigeration cycle device including 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates, a heat storage temperature sensor that detects the temperature of the heat storage material, and a control device that controls the switching valve and the expansion valve, wherein the control device controls the outdoor heat exchanger. the control device compares the detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation; and when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, the control device opens a second expansion valve disposed between the outdoor heat exchanger and the heat storage heat exchanger so that the refrigerant flowing out of the outdoor heat exchanger flows into the heat storage heat exchanger.

[0015] According to the present invention, even when air conditioning operation is performed in a refrigeration cycle device equipped with a heat storage heat exchanger, the capacity of the refrigeration cycle device can be prevented from decreasing by preventing refrigerant from stagnating inside the heat storage device and minimizing the reduction in the amount of refrigerant circulating through the refrigerant circuit.

[0016] 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to an embodiment of the present invention. 2 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to the embodiment of the present invention performs cooling operation. 3 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to the embodiment of the present invention performs heating operation. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to the first embodiment of the present invention performs heat-storage cooling operation. 5 is a block diagram showing the internal configuration of a control device in a refrigeration cycle apparatus according to an embodiment of the present invention. 6 is a flowchart showing the control flow when cooling operation is performed in the refrigeration cycle apparatus according to the first embodiment of the present invention. 7 is a flowchart showing the control flow when heat-storage cooling operation is performed in the refrigeration cycle apparatus according to the first embodiment of the present invention. 8 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to the second embodiment of the present invention performs cooling operation. 9 is a flowchart showing the control flow when cooling operation is performed in the refrigeration cycle apparatus according to the second embodiment of the present invention.

[0017] (First embodiment) 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 in which a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4, expansion valves 5 (51, 52, 53), and switching valves 6 (61, 62) are connected, and which 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.

[0018] The compressor 1 compresses the refrigerant circulating through the refrigerant circuit C. The indoor heat exchanger 2 exchanges heat between the refrigerant and indoor air. The outdoor heat exchanger 3 exchanges heat between the refrigerant and outdoor air. 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 may be used.

[0019] The thermal storage heat exchanger 4 is a heat exchanger that exchanges heat between a thermal storage material and a refrigerant passing 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 in a thermal storage container filled with a thermal storage material.

[0020] 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. The heat storage material stores heat supplied from the refrigerant, and the stored heat is used, for example, during defrosting operation of the outdoor heat exchanger 3. As will be described later, in the first embodiment of the present invention, the heat storage material is used to prevent the refrigerant flowing into the heat storage heat exchanger 4 from condensing and remaining in the heat storage heat exchanger 4 during cooling operation.

[0021] The heat storage heat exchanger 4 is also provided with a heat storage temperature sensor HS that measures the temperature of the heat storage material. Only one or more heat storage temperature sensors HS may be provided. For example, when more than one heat storage temperature sensor HS is provided, the detected temperature of the heat storage material may be calculated, for example, by taking the average of the values ​​detected by the respective heat storage temperature sensors HS as the temperature of the heat storage material, and the calculated temperature may be used for control, which will be described later.

[0022] Furthermore, a refrigerant temperature sensor RS is provided between the heat storage heat exchanger 4 and the second expansion valve 52. The refrigerant temperature sensor RS detects the temperature of the refrigerant flowing into the heat storage heat exchanger 4. This temperature is correlated with the saturation temperature of the refrigerant in the indoor heat exchanger 2, which functions as an evaporator during cooling operation.

[0023] The refrigerant temperature detected by the refrigerant temperature sensor RS is used to determine whether or not the refrigerant flowing into the heat storage heat exchanger 4 during cooling operation will condense inside the heat storage heat exchanger 4, i.e., whether or not to perform the heat storage cooling operation described below. Hereinafter, the refrigerant temperature detected by the refrigerant temperature sensor RS will be referred to as the "first predetermined temperature."

[0024] The opening degree of the expansion valve 5 can be adjusted based on an instruction from a control device 7, which will be described later, and a plurality of expansion valves are provided in the refrigeration cycle apparatus S according to the embodiment of the present invention. Specifically, three expansion valves are provided, and the first expansion valve 51 is provided upstream in the refrigerant flow direction when the thermal storage heat exchanger 4 functions as a condenser.

[0025] The second expansion valve 52 is provided between the heat storage heat exchanger 4 and the outdoor heat exchanger 3. That is, the second expansion valve 52 is provided downstream in the refrigerant flow direction when the heat storage heat exchanger 4 functions as a condenser. Specifically, the second expansion valve 52 is provided in a refrigerant pipe connected at one end to the refrigerant pipe connecting the indoor heat exchanger 2 and the outdoor heat exchanger 3, and at the other end to the heat storage heat exchanger 4. The third expansion valve 53 is provided between the indoor heat exchanger 2 and the outdoor heat exchanger 3. That is, the third expansion valve 53 is provided downstream in the refrigerant flow direction when the indoor heat exchanger 2 functions as a condenser. Specifically, the third expansion valve 53 is provided in a refrigerant pipe connected at one end to the refrigerant pipe connecting the outdoor heat exchanger 3 and the second expansion valve 52, and at the other end to the indoor heat exchanger 2.

[0026] The switching valve 6 switches the circulation path of the refrigerant in the refrigerant circuit C. For example, the circulation path is switched between a normal cooling operation in which the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 2 functions as an evaporator, and a heat-storage cooling operation (described later) in which the heat-storage heat exchanger 4 functions as a condenser and the indoor heat exchanger 2 and the outdoor heat exchanger 3 function as evaporators.

[0027] Furthermore, the refrigeration cycle apparatus S according to the embodiment of the present invention is provided with two switching valves 6. That is, a first switching valve 61 is provided between the compressor 1 and the indoor heat exchanger 2. Furthermore, a second switching valve 62 is provided between the compressor 1 and the outdoor heat exchanger 3 or the thermal storage heat exchanger 4.

[0028] In the following description, the first expansion valve 51 to the third expansion valve 53 will be referred to as the "expansion valve 5" when collectively describing them, and each individual expansion valve will be referred to by its respective name when describing them individually. Similarly, the switching valve 6 will be referred to as the "switching valve 6" when collectively describing the first switching valve 61 and the second switching valve 62, and each individual switching valve will be referred to by its respective name when describing them individually.

[0029] Furthermore, in the refrigeration cycle device S according to the embodiment of the present invention, the cooling operation is not stopped even when the heat storage operation is performed on the heat storage heat exchanger 4, and a heat storage cooling operation is performed in parallel with the heat storage operation.

[0030] Next, the refrigerant circuit C of the refrigeration cycle apparatus S according to the embodiment of the present invention shown in Fig. 1 will be described. The refrigerant circuit C is composed of the above-described devices, such as the compressor 1, and refrigerant piping connecting these devices through which the refrigerant flows. A first switching valve 61 is provided in the refrigerant piping connecting the compressor 1 and the indoor heat exchanger 2. A second switching valve 62 is also provided in the refrigerant piping between the compressor 1 and the first switching valve 61, and allows the refrigerant discharged from the compressor 1 to flow to the outdoor heat exchanger 3 or the heat storage heat exchanger 4.

[0031] Furthermore, in the refrigeration cycle apparatus S according to the embodiment of the present invention, a bypass circuit B is provided between the first selector valve 61 and the second selector 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. 1. That is, as will be described later, when cooling operation is performed, the refrigerant flows from the first selector valve 61 to the second selector valve 62.

[0032] The control device 7 controls the apertures of the plurality of expansion valves 5. The control device 7 controls the apertures of each expansion valve, thereby adjusting the flow rate of the refrigerant circulating 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. By controlling the plurality of expansion valves 5 and the plurality of switching valves 6 in this manner, the control device 7 switches the operating mode, for example, between cooling operation and heat-storage cooling operation in which heat storage operation for the heat storage heat exchanger 4 is performed in parallel.

[0033] In this way, the control device 7 performs control such as switching the operation mode in the refrigeration cycle apparatus S. Before describing the functions of each part of the control device 7 of the refrigeration cycle apparatus S in the embodiment of the present invention, the operation modes performed in the refrigeration cycle apparatus S will first be described in order using the circuit diagrams of the refrigeration cycle apparatus S in the embodiment of the present invention shown in Figures 2 to 4.

[0034] 2 to 4, the refrigerant circuits C through which the refrigerant actually flows are indicated by solid lines. On the other hand, the refrigerant circuits C through which the refrigerant does not flow are indicated by dashed lines. The direction of the refrigerant circulating in the refrigerant circuits C is indicated by arrows.

[0035] First, normal 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.

[0036] 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 first expansion valve 51 and the second switching valve 62, as shown by the arrows in Fig. 2. At this time, the first 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.

[0037] 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.

[0038] The refrigerant that has thus released heat to the outside air flows out of the outdoor heat exchanger 3 and is reduced in pressure to become a low-temperature, low-pressure refrigerant by passing through the third expansion valve 53. The low-temperature, low-pressure refrigerant then flows into the indoor heat exchanger 2, where it exchanges heat with the indoor air.

[0039] 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 21 is cooled and supplied to the room by the indoor fan to cool the room. The refrigerant that has absorbed heat through heat exchange then flows into the compressor 1 through the first switching valve 61.

[0040] During cooling operation, the third expansion valve 53, through which the refrigerant condensed in the outdoor heat exchanger 3 passes, is controlled to an opening degree according to the user's request. On the other hand, the second expansion valve 52 is controlled to be fully closed, so that the refrigerant flowing out of the outdoor heat exchanger 3 does not flow into the thermal storage heat exchanger 4.

[0041] Next, the flow of the refrigerant when the refrigeration cycle apparatus S performs heating operation is as shown in Fig. 3. Fig. 3 is a refrigerant circuit diagram showing the flow of the refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs heating operation.

[0042] 3, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. On the other hand, the first expansion valve 51 provided between the compressor 1 and the first switching valve 61 is controlled to be fully closed, and therefore the refrigerant does not flow into the outdoor heat exchanger 3 via the second switching valve 62 as in the cooling operation described above.

[0043] 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 heated air to the indoor space by absorbing heat from the refrigerant. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0044] The refrigerant flowing out of the indoor heat exchanger 2 is reduced in pressure by passing through the third expansion valve 53, becoming a low-temperature, low-pressure refrigerant, 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.

[0045] As described above, the refrigeration cycle apparatus S according to 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. However, when the normal cooling operation or heating operation described above is performed, the heat storage heat exchanger 4 does not function as a condenser or an evaporator. Therefore, for example, during cooling operation, the second expansion valve 52 is fully closed to prevent the refrigerant flowing out of the outdoor heat exchanger 3 from flowing into the heat storage heat exchanger 4.

[0046] However, as described above, even if the second expansion valve 52 is fully closed, due to the structure of the expansion valve, a small amount of the refrigerant flowing from the outdoor heat exchanger 3 to the indoor heat exchanger 2 flows into the heat storage heat exchanger 4 via the second expansion valve 52.

[0047] The refrigerant that flows into the heat storage heat exchanger 4 exchanges heat with the heat storage material provided in the heat storage heat exchanger 4. In this case, if the temperature of the heat storage material is lower than that of the refrigerant that flows in, the refrigerant may condense into a liquid phase refrigerant. This phenomenon is particularly likely to occur when the heat storage heat exchanger 4 is disposed in, for example, an outdoor unit and the temperature outside the outdoor unit is very low.

[0048] When the refrigerant that has flowed into the heat-storage heat exchanger 4 reaches this liquid phase, as described above, the refrigerant accumulates inside the heat storage device, and since the density of the refrigerant in the liquid phase is high, the amount of refrigerant circulating through the refrigerant circuit decreases, which may lead to a decrease in the capacity of the refrigeration cycle device.

[0049] Therefore, as will be described later, during cooling operation, the control device 7 compares the temperature of the heat storage material with the (evaporation) temperature of the refrigerant that has flowed into the heat-storage heat exchanger 4. If the control device 7 determines that the former temperature is lower than the latter temperature, the operation mode is switched from cooling operation to heat-storage cooling operation.

[0050] The flow of refrigerant during the heat-storage cooling operation will now be described with reference to Fig. 4. Fig. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the first embodiment of the present invention performs the heat-storage cooling operation.

[0051] The reason for performing the heat storage cooling operation is to prevent the refrigerant that has flowed into the heat storage heat exchanger 4 from condensing into a liquid phase refrigerant. Therefore, in order to raise the temperature of the heat storage material, high-temperature refrigerant immediately after being discharged from the compressor 1 is caused to flow into the heat storage heat exchanger 4 to exchange heat with the heat storage material, thereby storing heat in the heat storage material.

[0052] That is, the refrigerant compressed by the compressor 1 and discharged in a high-temperature, high-pressure state flows into the heat storage heat exchanger 4 via the first expansion valve 51 and the second switching valve 62, as shown by the arrows in Fig. 4. At this time, the first 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 heat storage heat exchanger 4 from the second switching valve 62.

[0053] 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. Therefore, the heat-storage heat exchanger 4 at this time functions as a condenser.

[0054] The refrigerant flowing out of the thermal storage heat exchanger 4 is decompressed to become a low-temperature, low-pressure refrigerant by passing through the second expansion valve 52 and the third expansion valve 53. The low-temperature, low-pressure refrigerant then flows into the indoor heat exchanger 2, where it exchanges heat with the indoor air.

[0055] 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 the indoor fan to cool the room. The refrigerant that has absorbed heat through heat exchange then flows into the compressor 1 through the first switching valve 61.

[0056] The refrigerant flowing out from the heat storage heat exchanger 4 further flows into the outdoor heat exchanger 3 via the second expansion valve 52, and then flows out from the outdoor heat exchanger 3 and into the compressor 1 via the second switching valve 62.

[0057] Next, a more detailed description will be given of the control performed by the control device 7. Fig. 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 temperature detection unit 71, a storage unit 72, a determination unit 73, and a switching control unit 74.

[0058] The temperature detection unit 71 acquires the temperature of the heat storage material detected by a heat storage temperature sensor HS provided in the heat storage heat exchanger 4. The temperature of the heat storage material detected by the heat storage temperature sensor HS is, for example, the temperature of the heat storage material when heat exchange occurs with the refrigerant discharged from the compressor 1 and flowing into the heat storage heat exchanger 4 during heat storage cooling operation.

[0059] The temperature of the heat storage material detected by the heat storage temperature sensor HS may be constantly transmitted from the heat storage temperature sensor HS to the temperature detection unit 71. Alternatively, conversely, the temperature detection unit 71 may acquire the temperature from the heat storage temperature sensor HS as needed.

[0060] The temperature detection unit 71 also acquires the refrigerant temperature (first predetermined temperature) detected by the refrigerant temperature sensor RS. The refrigerant temperature detected by the refrigerant temperature sensor RS is the temperature of the refrigerant flowing from the outdoor heat exchanger 3 to the indoor heat exchanger 2 that has flowed into the heat storage heat exchanger 4 via the fully closed second expansion valve 52. Because the second expansion valve 52 is fully closed, the amount of refrigerant flowing at this time is small compared to the amount of refrigerant flowing from the outdoor heat exchanger 3 to the indoor heat exchanger 2. The evaporating temperature may also be constantly transmitted from the refrigerant temperature sensor RS to the temperature detection unit 71, or the temperature detection unit 71 may acquire it from the refrigerant temperature sensor RS as needed.

[0061] In this embodiment, the first predetermined temperature is the value detected by a refrigerant temperature sensor that detects the temperature of the refrigerant flowing into the heat-storage heat exchanger 4, but this is not limiting. For example, because the temperature of the refrigerant flowing into the heat-storage heat exchanger 4 is correlated with the saturation temperature of the refrigerant in the indoor heat exchanger 2, the first predetermined temperature may be set based on the value detected by, for example, an intermediate temperature sensor (not shown) that detects the temperature of the refrigerant flowing into the indoor heat exchanger 2. In this case, there is a difference in pressure loss between the path from the branching point to the inlet of the heat-storage heat exchanger 4 and the path from the branching point to the position detected by the intermediate temperature sensor in the indoor heat exchanger. Therefore, by correcting the predetermined value taking the pressure loss into account, refrigerant stagnation in the heat-storage heat exchanger can be more accurately prevented.

[0062] Furthermore, the indoor temperature (room temperature) detected by a temperature sensor (not shown) provided in the indoor heat exchanger 2 is also acquired by the temperature detection unit 71. The temperatures of the heat storage material and the refrigerant are used in control of heat storage in the heat storage heat exchanger 4.

[0063] The storage unit 72 is configured, for example, by a semiconductor or a magnetic disk. The storage unit 72 stores, for example, a set temperature, a first predetermined temperature, and a second predetermined temperature set in an indoor unit including the indoor heat exchanger 2 that constitutes the refrigeration cycle apparatus S.

[0064] The determination unit 73 determines whether to switch the operation mode to the heat-storage cooling operation during the cooling operation, for example. Specifically, the determination unit 73 uses the temperature of the heat storage material in the heat-storage heat exchanger 4 and the saturation temperature (first predetermined temperature) of the refrigerant to determine whether to cause the refrigerant to flow into the heat-storage heat exchanger 4 and store heat in the heat storage material.

[0065] That is, when the refrigeration cycle apparatus S is performing cooling operation, as described with reference to Fig. 2, the high-temperature, high-pressure refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 and is condensed. The refrigerant then flows out of the outdoor heat exchanger 3 and becomes a low-temperature, low-pressure refrigerant when passing through an expansion valve (here, the third expansion valve 53 as shown in Fig. 1) and flows into the indoor heat exchanger 2.

[0066] The indoor heat exchanger 2 functions as an evaporator to supply cool air to the room. The refrigerant then flows out of the indoor heat exchanger 2 into the compressor 1. During this cooling operation, the second expansion valve 52 is closed, and the refrigerant that flows out of the outdoor heat exchanger 3 does not generally flow into the thermal storage heat exchanger 4.

[0067] However, as described above, due to the structure of the second expansion valve 52, a small amount of refrigerant flows even when the second expansion valve 52 is fully closed, and it is therefore unavoidable that the refrigerant that flows out of the outdoor heat exchanger 3 will flow into the heat storage heat exchanger 4. When the refrigerant flows into the heat storage heat exchanger 4 in this way, if the heat storage heat exchanger 4 is disposed inside an outdoor unit, the temperature outside the outdoor unit is very low, and the heat storage material is cooled by the outside air, the refrigerant will condense inside the heat storage heat exchanger 4 and become a liquid-phase refrigerant.

[0068] When the refrigerant reaches a liquid phase in this way, the refrigerant accumulates inside the heat storage heat exchanger 4, and combined with its high density, the amount of refrigerant circulating through the refrigerant circuit C decreases, which may lead to a decrease in the capacity of the refrigeration cycle apparatus S.

[0069] Therefore, in the refrigeration cycle apparatus S in the first embodiment of the present invention, the heat storage cooling operation is performed as explained using Fig. 4. That is, the heat storage cooling operation is an operating mode in which heat is stored in the heat storage material provided inside the heat storage heat exchanger 4 during cooling operation. By performing the heat storage cooling operation, heat is stored in the heat storage material of the heat storage heat exchanger 4, and condensation of the refrigerant that has flowed into the heat storage heat exchanger 4 inside the heat storage heat exchanger 4 is prevented during cooling operation.

[0070] Specifically, when the refrigeration cycle apparatus S is performing cooling operation, the determination unit 73 obtains the temperature of the heat storage material from the heat storage temperature sensor HS via the temperature detection unit 71. At the same time, the determination unit 73 obtains the temperature of the refrigerant flowing out from the second expansion valve 52 (first predetermined temperature) from the refrigerant temperature sensor RS. Then, the determination unit 73 compares the temperature of the heat storage material with the first predetermined temperature.

[0071] If the determination unit 73 determines as a result of the comparison that the temperature of the heat storage material is lower than the first predetermined temperature, it switches the operation mode from air conditioning operation to heat-storage air conditioning operation and starts the heat-storage air conditioning operation. That is, the determination unit 73 issues an instruction to the switching control unit 74 to switch the operation mode to heat-storage air conditioning operation. The switching control unit 74 switches the expansion valve 5 and the switching valve 6 based on the instruction of the determination unit 73.

[0072] As described above, in the cooling operation, the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 via the first expansion valve 51 and the second switching valve 62. On the other hand, when the determination unit 73 determines that the operation mode should be switched from the cooling operation to the heat-storage cooling operation, the switching control unit 74 controls the second switching valve 62 based on an instruction from the determination unit 73 to switch the flow path of the refrigerant.

[0073] The aperture of the second expansion valve 52 is controlled from a fully closed state to a preset initial aperture, and then the aperture is controlled so that the temperature of the refrigerant discharged from the compressor 1 (discharge temperature) becomes a target discharge temperature. The initial aperture is set based on the evaporation pressure, the rotation speed of the compressor 1, etc. The target discharge temperature is set based on the condensation pressure, evaporation pressure, and the rotation speed of the compressor 1, and is a target value of the discharge temperature at which the refrigerant sucked into the compressor is in an optimal state.

[0074] When the second switching valve 62 is switched by the switching control unit 74, the high-temperature refrigerant discharged from the compressor 1 flows directly into the heat storage heat exchanger 4 rather than into the outdoor heat exchanger 3 (heat storage cooling operation). In the heat storage heat exchanger 4 into which the refrigerant from the compressor 1 flows, heat exchange occurs between the high-temperature refrigerant and the heat storage material, and the heat of the refrigerant is transferred to the heat storage material and stored in the heat storage material.

[0075] In this case, the heat storage heat exchanger 4 serves as a condenser, and the refrigerant that has exchanged heat in the heat storage heat exchanger 4 passes through the second expansion valve 52 and flows into the indoor heat exchanger 2. The indoor heat exchanger 2 functions as an evaporator, exchanging heat between the refrigerant that has flowed in and the indoor air to supply cool air into the room. In this way, in the heat storage cooling operation, heat is stored in the heat storage heat exchanger 4 and the indoor heat exchanger 2 is used as an evaporator, so that cooling operation can be performed simultaneously.

[0076] The refrigerant flowing out of the thermal storage heat exchanger 4 also flows into the outdoor heat exchanger 3 via the second expansion valve 52. In this case, the outdoor heat exchanger 3 also functions as an evaporator, similar to the indoor heat exchanger 2. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the compressor 1 via the second switching valve 62.

[0077] In the heat-storage cooling operation, as described above, the refrigerant flowing out of the heat-storage heat exchanger 4 flows into the indoor heat exchanger 2, but the cooling operation continues. The determination unit 73 further compares the current indoor temperature (room temperature) with the temperature set by the user. This is to determine the opening degree of the third expansion valve 53, that is, how much of the refrigerant flowing out of the heat-storage heat exchanger 4 should be allowed to flow into the indoor heat exchanger 2 depending on the current situation.

[0078] Specifically, the determination unit 73 obtains information about the room temperature via the temperature detection unit 71, and also obtains information about the temperature set by the user from the storage unit 72. Then, the determination unit 73 compares the room temperature with the set temperature.

[0079] If the comparison shows that the room temperature is lower than the set temperature, the room is sufficiently cooled, and further operation of the indoor unit may actually reduce user comfort. Therefore, there is no need to lower the temperature any further, and it is sufficient not to flow refrigerant through the indoor heat exchanger 2.

[0080] Therefore, the determination unit 73 issues an instruction to the switching control unit 74 to fully close the third expansion valve 53. The switching control unit 74 fully closes the third expansion valve 53 based on the instruction from the determination unit 73. In this case, the refrigerant flowing out of the heat storage heat exchanger 4 does not flow into the indoor heat exchanger 2, but only into the outdoor heat exchanger 3, so the circuit to which the outdoor heat exchanger 3 is connected can be used as a bypass circuit. Therefore, in cases where sufficient heat storage is required in the heat storage heat exchanger 4 but such high capacity is not required in the indoor heat exchanger 2, a place for the refrigerant to go can be secured, and both requirements can be met.

[0081] On the other hand, if the determination unit 73 determines that the room temperature is higher than the set temperature, it is necessary to continue supplying cool air to the room. Therefore, the determination unit 73 instructs the switching control unit 74 to fully open the third expansion valve 53. The switching control unit 74 fully opens the third expansion valve 53 based on the instruction from the determination unit 73.

[0082] The determination unit 73 determines whether to terminate the heat storage cooling operation and switch the operation mode to normal cooling operation. To do so, the determination unit 73 compares the temperature of the heat storage material measured by the heat storage temperature sensor HS with a second predetermined temperature stored in advance in the memory unit 72.

[0083] As explained above, the reason for performing the heat storage cooling operation is to store heat in the heat storage material to prevent the refrigerant flowing into the heat storage heat exchanger 4 from the second expansion valve 52, which is fully closed during cooling operation, from condensing and becoming a liquid phase refrigerant through heat exchange with the heat storage material in the heat storage heat exchanger 4.

[0084] Therefore, even if refrigerant flows from the outdoor heat exchanger 3 to the heat-storage heat exchanger 4 during cooling operation, it is sufficient that heat is stored in the heat storage material to the extent that condensation does not occur. On the other hand, frequent switching between cooling operation and heat-storage cooling operation may ultimately result in a loss of user comfort. Furthermore, during heat-storage cooling operation, the higher the rotation speed of the compressor 1, the higher the temperature of the refrigerant supplied to the heat-storage heat exchanger 4. However, if the rotation speed is increased too much, the high-pressure will rise excessively, causing the protective control to be activated and the compressor 1 to stop.

[0085] In this way, it is necessary to reduce the frequency of switching the operating mode from cooling operation to heat-storage cooling operation while storing heat sufficiently in the heat storage material, and it is necessary to strike a balance between these two.

[0086] Therefore, the "second predetermined temperature" is set to a temperature at which the compressor 1 can be driven at a rotation speed at which the protection control is not activated during the heat storage cooling operation and heat can be stored in the heat storage material. Specifically, the temperature is set to, for example, 50°C.

[0087] If the determination unit 73 determines that the temperature of the heat storage material is lower than the second predetermined temperature, the amount of heat stored in the heat storage material is still insufficient, and the heat storage cooling operation continues. On the other hand, if the determination unit 73 determines that the temperature of the heat storage material is equal to or higher than the second predetermined temperature, the heat storage cooling operation is terminated. The determination unit 73 then instructs the switching control unit 74 to switch the operating mode to normal cooling operation.

[0088] [Operation] Next, the control flow of the refrigeration cycle apparatus S by the control device 7 in the above-mentioned cooling operation and heat-storage cooling operation will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a flowchart showing the control flow when performing the cooling operation in the refrigeration cycle apparatus S according to the first embodiment of the present invention. Also, Fig. 7 is a flowchart showing the control flow when performing the heat-storage cooling operation in the refrigeration cycle apparatus S according to the first embodiment of the present invention.

[0089] First, normal cooling operation is started in the refrigeration cycle apparatus S (ST1). Conditions for starting the cooling operation are set in advance, and the control device 7 determines whether or not the conditions are met. A possible condition for starting the cooling operation is, for example, when a user sets a set temperature and starts the cooling operation.

[0090] When the cooling operation is started, as described above, the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 via the first expansion valve 51, the second switching valve 62, and the first switching valve 61. The refrigerant condensed in the outdoor heat exchanger 3 flows into the indoor heat exchanger 2 via the third expansion valve 53. In the indoor heat exchanger 2, heat exchange occurs between the refrigerant and the indoor air, and cool air is supplied to the room. The refrigerant that has flowed out of the indoor heat exchanger 2 flows into the compressor 1 via the first switching valve 61.

[0091] During cooling operation, the second expansion valve 52 is controlled by the switching control unit 74 to be fully closed. Therefore, the refrigerant flowing out of the outdoor heat exchanger 3 is prevented from flowing into the heat storage heat exchanger 4. However, as described above, a small amount of the refrigerant flowing from the outdoor heat exchanger 3 to the indoor heat exchanger 2 flows into the heat storage heat exchanger 4.

[0092] Therefore, the control device 7 acquires information on the temperature of the heat storage material during cooling operation and information on the saturation temperature of the refrigerant flowing from the outdoor heat exchanger 3 to the heat storage heat exchanger 4. Specifically, the control device 7 acquires information on the temperature of the heat storage material detected by the heat storage temperature sensor HS and information on the temperature of the refrigerant detected by the refrigerant temperature sensor RS via the temperature detection unit 71.

[0093] Then, the determination unit 73 compares the temperature of the heat storage material with the temperature of the refrigerant (first predetermined temperature) (ST2). As a result, if it is determined that the temperature of the heat storage material is a high temperature equal to or higher than the first predetermined temperature (NO in ST3), the process returns to step ST2 and the temperature of the heat storage material is compared again with the first predetermined temperature. In this case, even if part of the refrigerant flows from the outdoor heat exchanger 3 into the heat-storage heat exchanger 4, it is unlikely that the refrigerant will condense into a liquid-phase refrigerant, so there is no need to switch to heat-storage cooling operation.

[0094] On the other hand, if the determination unit 73 determines that the temperature of the heat storage material is lower than the first predetermined temperature (YES in ST3), there is a possibility that the refrigerant that has flowed into the heat-storage heat exchanger 4 will condense into a liquid-phase refrigerant. Therefore, the operation mode is switched from normal cooling operation to heat-storage cooling operation, and the heat-storage cooling operation is started (ST4).

[0095] In this case, after the compressor 1 is stopped, the switching control unit 74 controls the second switching valve 62 to switch the refrigerant flow path based on the judgment result of the judgment unit 73 as described above, so that the refrigerant discharged from the compressor 1 flows into the heat storage heat exchanger 4 instead of flowing into the outdoor heat exchanger 3.

[0096] As a result, the operating mode switches to heat storage cooling operation (ST41 in FIG. 7), and the determination unit 73 compares the indoor temperature with the set temperature for cooling operation set by the user (ST42). This is because in heat storage cooling operation, the heat storage heat exchanger 4 functions as a condenser, and the opening degree of the third expansion valve 53 is determined to determine how much of the refrigerant flowing out of the heat storage heat exchanger 4 should flow into the indoor heat exchanger 2 depending on the current situation.

[0097] Therefore, the determination unit 73 compares the indoor temperature with the set temperature to allow the refrigerant corresponding to the capacity required by the indoor unit to flow into the indoor heat exchanger 2. As a result, if it is determined that the room temperature is lower than the set temperature (YES in ST43), the third expansion valve 53 is controlled to be fully closed (ST44).

[0098] That is, in this case, there is no need to pass the refrigerant flowing out of the heat storage heat exchanger 4 to the indoor heat exchanger 2, and the refrigerant passes only to the outdoor heat exchanger 3. On the other hand, if the determination unit 73 determines that the room temperature is equal to or higher than the set temperature (NO in ST43), the third expansion valve 53 is controlled to be fully open, and cool air continues to be supplied to the room (ST45).

[0099] The determination unit 73 determines whether sufficient heat has been stored in the heat storage material during the heat storage cooling operation. Specifically, the determination unit 73 compares the temperature of the heat storage material with a second predetermined temperature (ST5). The temperature of the heat storage material is obtained from the heat storage temperature sensor HS, and the second predetermined temperature is obtained from the memory unit 72.

[0100] As a result, if the temperature of the heat storage material is lower than the second predetermined temperature (NO in ST5), there is still a possibility that the refrigerant flowing into the heat storage heat exchanger 4 will condense and become a liquid phase refrigerant, so the heat storage cooling operation will continue.

[0101] On the other hand, if the determination unit 73 determines that the temperature of the heat storage material is equal to or higher than the second predetermined temperature (NO in ST5), the refrigerant is unlikely to condense into a liquid phase refrigerant even if it flows into the heat storage heat exchanger 4. Therefore, the operation mode is switched from the heat storage cooling operation to the cooling operation (ST6).

[0102] As explained above, by performing heat storage cooling operation, even when cooling operation is performed in a refrigeration cycle device equipped with a heat storage heat exchanger, it is possible to prevent refrigerant from stagnating inside the heat storage device and to minimize the reduction in the amount of refrigerant circulating through the refrigerant circuit.

[0103] Furthermore, if the refrigerant flows into the heat storage heat exchanger during cooling operation, condenses into a liquid phase, and accumulates inside the heat storage heat exchanger, the amount of refrigerant circulating in the refrigeration cycle device will decrease. In such a case, when cooling operation is performed, the enthalpy difference will be small when the amount of refrigerant is small, and the power consumption in the compressor 1 will be larger than in normal cooling operation, resulting in a decrease in the energy-saving performance of the entire refrigeration cycle device.

[0104] However, by performing the heat-storage cooling operation according to the first embodiment of the present invention, the amount of refrigerant remaining in the heat-storage heat exchanger can be reduced, thereby avoiding a significant reduction in the total amount of refrigerant circulating through the refrigerant circuit, and as a result, preventing a decrease in the energy-saving performance of the entire refrigeration cycle apparatus.

[0105] In the first embodiment, when it is determined that the temperature of the heat storage material has become lower than the first predetermined temperature during cooling operation, the operation mode is switched from cooling operation to heat-storage cooling operation. However, the timing of switching the operation mode from cooling operation to heat-storage cooling operation is not limited to this timing.

[0106] For example, the refrigeration cycle apparatus S may enter a so-called thermo-off state during cooling operation. Because the thermo-off state occurs, heat exchange between the indoor air and the refrigerant does not occur in the indoor heat exchanger 2. Therefore, when the determination unit 73 determines that the thermo-off state has occurred during such cooling operation, it performs control to switch the operation mode from cooling operation to heat-storage cooling operation.

[0107] Then, by flowing high-temperature refrigerant from the compressor 1 into the heat-storage heat exchanger 4, heat is stored in the heat storage material. Furthermore, the third expansion valve 53 is controlled to be closed so that the refrigerant flowing out of the heat-storage heat exchanger 4 does not flow into the indoor heat exchanger 2, but only into the outdoor heat exchanger 3. By performing such control, it is possible to actively perform heat-storage cooling operation when cooling capacity is not required in the indoor unit, and to store heat in the heat storage material. It is also possible to prevent the refrigerant flowing into the heat-storage heat exchanger 4 from condensing into a liquid-phase refrigerant during cooling operation.

[0108] In particular, by effectively utilizing the thermo-off state, the frequency of switching the operating mode from cooling operation to heat storage cooling operation can be reduced, thereby reducing the possibility of compromising user comfort.

[0109] Furthermore, when the heat storage cooling operation is performed, the refrigerant flowing out of the heat storage heat exchanger 4 flows not only into the indoor heat exchanger 2 but also into the outdoor heat exchanger 3. Therefore, the amount of refrigerant flowing into the indoor heat exchanger 2 decreases, which may result in a corresponding decrease in the capacity of the indoor unit.

[0110] Therefore, for example, an on-off valve can be provided between the second expansion valve 52 and the outdoor heat exchanger 3. By providing this on-off valve, it is possible to prevent the refrigerant that flows out of the heat storage heat exchanger 4 from flowing into the outdoor heat exchanger 3 during heat storage cooling operation. Since no refrigerant flows into the outdoor heat exchanger 3, almost the entire amount of refrigerant that flows out of the heat storage heat exchanger 4 flows into the indoor heat exchanger 2. This makes it possible to avoid impairing the capacity of the indoor unit.

[0111] Furthermore, in the heat storage cooling operation, the above description has been given with reference to an example in which the third expansion valve 53 is fully closed or fully open when the refrigerant flowing out of the heat storage heat exchanger 4 flows into the indoor heat exchanger 2. However, the present invention is not limited to such control.

[0112] That is, depending on the temperature set by the user in the indoor unit, there may be cases where a large cooling capacity is not required from the indoor unit. In such cases, the control device 7 can respond by setting the opening degree of the third expansion valve 53 in accordance with the user's request.

[0113] That is, for example, during cooling operation, if the difference between the room temperature and the set temperature is small and not much capacity is required of the indoor unit, control is performed to throttle the third expansion valve 53. On the other hand, if the difference between the room temperature and the set temperature is large, a large load is placed on the indoor unit, so control is performed to increase the opening of the third expansion valve 53. That is, during heat storage cooling operation, the amount of refrigerant flowing into the indoor heat exchanger 2 can be adjusted according to the cooling capacity of the indoor unit.

[0114] Even if control is performed according to the capacity of the indoor unit in this way, the refrigerant that flows out of the heat storage heat exchanger 4 during heat storage cooling operation also flows into the outdoor heat exchanger 3. In other words, the circuit to which the outdoor heat exchanger 3 is connected can be used as a bypass circuit. Therefore, in cases where sufficient heat storage is required in the heat storage heat exchanger 4 but such capacity is not required in the indoor heat exchanger 2, a place for the refrigerant to go can be secured, and both requirements can be met.

[0115] Second Embodiment Next, a second embodiment of the present invention will be described. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and redundant descriptions of the same components will be omitted.

[0116] In the first embodiment described so far, in order to prevent the refrigerant flowing from the outdoor heat exchanger 3 from condensing in the heat storage heat exchanger 4 during cooling operation to become a liquid phase refrigerant, the operation mode is switched from cooling operation to heat storage cooling operation, and control is performed to store heat in the heat storage material.

[0117] In contrast to this, in the control in the second embodiment, the heat storage cooling operation is not performed, and the cooling operation is performed while the refrigerant flowing out from the outdoor heat exchanger 3 is also flowed into the heat storage heat exchanger 4. By performing this control, the refrigerant stagnating inside the heat storage heat exchanger 4 can be pushed out and flowed into the compressor 1.

[0118] 8 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S1 according to the second embodiment of the present invention performs cooling operation. The components constituting the refrigeration cycle apparatus S1 are the same and arranged in the same manner. However, the flow of refrigerant discharged from the compressor 1 differs from that in the heat-storage cooling operation.

[0119] That is, the flow of refrigerant is basically the same as that in normal cooling operation described with reference to Fig. 2. As shown by the arrows in Fig. 8, the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 via the first expansion valve 51 and the second switching valve 62. The refrigerant condensed in the outdoor heat exchanger 3 flows into the indoor heat exchanger 2 via the third expansion valve 53, where the refrigerant exchanges heat with the indoor air to supply cool air into the room. The refrigerant flowing out of the indoor heat exchanger 2 flows into the compressor 1 via the first switching valve 61.

[0120] In the second embodiment, the refrigerant flow during cooling operation is controlled to open the second expansion valve 52. Since the second expansion valve 52 is controlled to open, the refrigerant flowing out of the outdoor heat exchanger 3 flows not only into the indoor heat exchanger 2 but also into the heat storage heat exchanger 4. The refrigerant flowing out of the heat storage heat exchanger 4 then flows into the compressor 1 via the second switching valve 62.

[0121] However, when the second expansion valve 52 is controlled to be in the open state in this way, the determination unit 73 of the control device 7 determines whether or not to perform this control. That is, the determination unit 73 compares the temperature of the heat storage material in the heat storage heat exchanger 4 with the temperature (first predetermined temperature) of the refrigerant flowing into the heat storage heat exchanger 4. This comparison is similar to the control in the first embodiment described above.

[0122] If the determination unit 73 determines that the temperature of the heat storage material is equal to or higher than the first predetermined temperature as a result of comparing the temperature of the heat storage material and the temperature of the refrigerant, normal cooling operation continues. Therefore, control to open the second expansion valve 52 is not performed. In this case, even if part of the refrigerant flows from the outdoor heat exchanger 3 into the heat storage heat exchanger 4 when the second expansion valve 52 is fully closed, it is unlikely to condense into a liquid-phase refrigerant.

[0123] On the other hand, when the determination unit 73 determines that the temperature of the heat storage material is lower than the first predetermined temperature, the determination unit 73 instructs the switching control unit 74 to open the second expansion valve 52. Based on the instruction from the determination unit 73, the switching control unit 74 controls the second expansion valve 52 to be open.

[0124] When the second expansion valve 52 is opened, a small amount of the refrigerant that has flowed out of the outdoor heat exchanger 3 flows into the heat storage heat exchanger 4. That is, the gas-liquid two-phase refrigerant that has flowed out of the outdoor heat exchanger 3 flows into the heat storage heat exchanger 4, which has been filled with liquid phase refrigerant.

[0125] The state in which liquid-phase refrigerant is stagnant inside the heat storage heat exchanger 4 during cooling operation means that the entire heat storage circuit, including the heat storage heat exchanger 4, is filled with the liquid-phase refrigerant. When gas-liquid two-phase refrigerant flows into the heat storage heat exchanger 4 in this state, a region of gas-phase refrigerant is created in the heat storage circuit. In other words, a density difference occurs between the region of gas-phase refrigerant and the region of liquid-phase refrigerant throughout the heat storage heat exchanger 4. Therefore, the amount of refrigerant in the entire heat storage heat exchanger 4 decreases. As a result, the amount of refrigerant used during cooling operation increases.

[0126] In other words, when gas phase refrigerant flows into a heat storage circuit that is filled with liquid phase refrigerant, the liquid phase refrigerant that was originally stagnating there is pushed out of the heat storage heat exchanger 4.

[0127] The liquid-phase refrigerant that is pushed out mixes with the gas-phase refrigerant that has flowed out from the indoor heat exchanger 2. Since the gas-phase refrigerant that has flowed out from the indoor heat exchanger 2 has been warmed, a portion of the liquid-phase refrigerant evaporates. This refrigerant returns to the compressor 1.

[0128] As described above, the switching control unit 74 controls the second expansion valve 52 to be in an open state, and in this case, the opening degree of the second expansion valve 52 is controlled as follows: That is, if the second expansion valve 52 is controlled to be fully open, there is a possibility that much of the refrigerant flowing out of the outdoor heat exchanger 3 will flow into the thermal storage heat exchanger 4 via the second expansion valve 52.

[0129] If a large amount of refrigerant flows into the heat storage heat exchanger 4 in this way, the amount of refrigerant flowing from the outdoor heat exchanger 3 into the indoor heat exchanger 2 will decrease. If the amount of refrigerant flowing into the indoor heat exchanger 2 decreases, the capacity of the indoor heat exchanger 2 will decrease, which may impair user comfort.

[0130] Therefore, considering that this control is only for cooling operation, it is preferable to control the amount of refrigerant that flows out of the outdoor heat exchanger 3 and flows into the indoor heat exchanger 2 and the heat storage heat exchanger 4 so that the amount of refrigerant flowing into the indoor heat exchanger 2 is greater than the amount of refrigerant flowing into the heat storage heat exchanger 4.

[0131] That is, when comparing the opening degrees of the second expansion valve 52 and the third expansion valve 53, the switching control unit 74 controls the opening degrees of the second expansion valve 52 and the third expansion valve 53 so that the opening degree of the latter is larger than the opening degree of the former. Note that the opening degree is defined as a ratio to when the expansion valves are fully open. In other words, the opening degrees of the second expansion valve 52 and the third expansion valve 53 are controlled so that the flow rate of the refrigerant passing through the third expansion valve 53 is larger than the flow rate of the refrigerant passing through the second expansion valve 52.

[0132] The opening degree of the second expansion valve 52 has the above-described relationship with the opening degree of the third expansion valve 53, but the actual opening degree can be determined by referring to the opening degree of the third expansion valve 53. Alternatively, it is also possible to control the opening degree to be set to a value obtained by experiment or the like, for example.

[0133] When the switching control unit 74 controls the second expansion valve 52 to be in the open state, the refrigerant flows from the outdoor heat exchanger 3 to the heat storage heat exchanger 4. In this state, the determination unit 73 checks the temperature difference between the temperature of the heat storage material and the temperature of the refrigerant. That is, the determination unit 73 obtains, via the temperature detection unit 71, information on the temperature of the heat storage material and information on the saturation temperature of the refrigerant obtained by the heat storage temperature sensor HS and the refrigerant temperature sensor RS, respectively.

[0134] The temperature difference to be compared is set in advance and stored in the memory unit 72. Therefore, when making the comparison, the determination unit 73 accesses the memory unit 72 to acquire information about the temperature difference. As a result, if the temperature difference between the temperature of the heat storage material and the temperature of the refrigerant is within the range of the preset temperature difference, the second expansion valve 52 continues to be controlled to be in the open state.

[0135] On the other hand, if the temperature difference between the temperature of the heat storage material and the temperature of the refrigerant is outside the preset temperature difference range, it is considered unlikely that the refrigerant will condense into a liquid-phase refrigerant even if it flows into the heat storage heat exchanger 4 from the outdoor heat exchanger 3. In this case, the determination unit 73 controls the second expansion valve 52 to be in the closed state via the switching control unit 74.

[0136] [Operation] Next, the flow of control of the refrigeration cycle apparatus S by the control device 7 in the cooling operation of the second embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the flow of control when the refrigeration cycle apparatus S1 according to the second embodiment of the present invention performs the cooling operation.

[0137] When the cooling operation is started (ST71), the determination unit 73 compares the temperature of the heat storage material with the temperature of the refrigerant (first predetermined temperature) (ST72), in order to determine whether or not to control the second expansion valve 52 to the open state, as described above.

[0138] When the comparison by the determination unit 73 determines that the temperature of the heat storage material is equal to or higher than the first predetermined temperature (NO in ST73), it is considered unlikely that the refrigerant flowing out from the outdoor heat exchanger 3 will condense into a liquid-phase refrigerant even if it flows into the heat-storage heat exchanger 4. Therefore, the second expansion valve 52 remains fully closed, and the cooling operation continues.

[0139] On the other hand, when the comparison by the determination unit 73 determines that the temperature of the heat storage material is lower than the first predetermined temperature (YES in ST73), the second expansion valve 52 is controlled to be in an open state via the switching control unit 74 (ST74). Note that the opening degree of the second expansion valve 52 is smaller than the opening degree of the third expansion valve 53, as described above.

[0140] Additionally, the determination unit 73 determines whether there is a predetermined temperature difference between the temperature of the heat storage material and the temperature of the refrigerant (ST75). If the result of the determination is that there is a predetermined temperature difference between the two (YES in ST75), the temperature rise of the heat storage material due to heat absorption from the refrigerant is insufficient, and even if the refrigerant from the exterior heat exchanger 3 flows into the heat storage heat exchanger 4, there is a high possibility that the refrigerant will condense into a liquid-phase refrigerant inside the heat storage heat exchanger 4. Therefore, in this case, the second expansion valve 52 continues to be open.

[0141] On the other hand, if the determination unit 73 determines that the temperature difference between the two does not satisfy the predetermined temperature difference (NO in ST75), the temperature of the heat storage material has risen due to heat absorption from the refrigerant, and when the refrigerant from the exterior heat exchanger 3 flows into the heat storage heat exchanger 4, it is difficult for the refrigerant to condense and become a liquid-phase refrigerant in the heat storage heat exchanger 4. Therefore, the second expansion valve 52 is controlled to be fully closed, preventing any further refrigerant from flowing into the heat storage heat exchanger 4 (ST76).

[0142] As explained above, by performing heat storage cooling operation, even when cooling operation is performed in a refrigeration cycle device equipped with a heat storage heat exchanger, it is possible to prevent refrigerant from stagnating inside the heat storage device and to minimize the reduction in the amount of refrigerant circulating through the refrigerant circuit.

[0143] Furthermore, by performing the control in the second embodiment, the amount of refrigerant remaining inside the heat-storage heat exchanger can be reduced, so the total amount of refrigerant circulating through the refrigerant circuit does not need to be significantly reduced, thereby preventing a decrease in the energy-saving performance of the refrigeration cycle device during cooling operation.

[0144] Furthermore, in the control according to the second embodiment, it is not necessary to change the refrigerant flow path from the outdoor heat exchanger 3 to the heat storage heat exchanger 4 by switching the second switching valve 62, and control is simply performed to open the second expansion valve 52. Therefore, with simpler control, it is possible to prevent the refrigerant that has become liquid phase refrigerant from accumulating inside the heat storage heat exchanger 4.

[0145] 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.

[0146] 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.

[0147] The technology described in the embodiment of the present invention may also be configured as follows: (1) A refrigerant circuit including 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, an expansion valve with an adjustable opening, and a switching valve that switches a flow path when the refrigerant circulates, a heat-storage temperature sensor that detects the temperature of the heat storage material, and a control device that controls the switching valve and the expansion valve, wherein the switching valve switches the flow path between a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, and a heat-storage cooling operation in which at least the indoor heat exchanger functions as an evaporator when the heat-storage heat exchanger functions as a condenser, (2) The refrigeration cycle apparatus according to (1), characterized in that the control device controls the switching valve to switch from the cooling operation to the heat-storage cooling operation when it determines that the temperature of the heat storage material detected by the heat storage temperature sensor has fallen below a first predetermined temperature during the cooling operation. (3) The refrigeration cycle apparatus according to (1) or (2), characterized in that the expansion valve is disposed between the outdoor heat exchanger and the indoor heat exchanger, and the control device adjusts the amount of the refrigerant flowing into the indoor heat exchanger during the heat-storage cooling operation. (4) The refrigeration cycle apparatus according to any one of (1) to (3), characterized in that the control device controls the switching valve to switch from the cooling operation to the heat-storage cooling operation when the thermostat is off during the cooling operation. (5) The refrigeration cycle device according to any one of (1) to (4) above, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.(6) A refrigeration cycle device comprising: 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 refrigerant circuit having: an expansion valve with an adjustable opening; and a switching valve that switches a flow path when the refrigerant circulates; a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the switching valve and the expansion valve, wherein the control device is configured to open a second expansion valve disposed between the outdoor heat exchanger and the heat storage heat exchanger, and control the refrigerant flowing out of the outdoor heat exchanger to flow into the heat storage heat exchanger during cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, when the control device determines that the detected value of the heat storage temperature sensor has become lower than a first predetermined temperature. (7) The refrigeration cycle apparatus according to (6), characterized in that, when the control device controls the second expansion valve to an open state, the control device controls the opening degree of the second expansion valve to be smaller than the opening degree of a first expansion valve disposed between the outdoor heat exchanger and the indoor heat exchanger. (8) The refrigeration cycle apparatus according to (6) or (7), characterized in that the first predetermined temperature is a detection value of a refrigerant temperature sensor. (9) The refrigeration cycle apparatus according to (8), characterized in that the control device controls the second expansion valve to be in a closed state when it determines that a difference between a detection value of the heat storage temperature sensor and a detection value of the refrigerant temperature sensor has reached a predetermined value.(10) A refrigeration cycle device comprising: 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates; a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the switching valve and the expansion valve, the refrigeration cycle device comprising: a step of performing a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator; and a step of the control device comparing a detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation. (11) The control method for a refrigeration cycle apparatus according to (10), characterized in that, after the step of comparing the detected value of the heat storage temperature sensor with the detected value of the refrigerant temperature sensor during the cooling operation by the control device, when it is determined by the control device that the temperature of the heat storage material detected by the heat storage temperature sensor has reached a predetermined temperature or higher, the control device controls the switch valve to switch from the heat storage cooling operation to the cooling operation, when it is determined by the control device that the temperature of the heat storage material detected by the heat storage temperature sensor has reached a predetermined temperature or higher. (12) The control method for a refrigeration cycle apparatus according to (10) or (11), characterized in that, when thermo-off is turned on during the cooling operation, the control device controls the switch valve to switch from the cooling operation to the heat storage cooling operation. (13) The method for controlling a refrigeration cycle device according to any one of (10) to (12) above, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.(14) A refrigeration cycle device comprising: 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates; a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the switching valve and the expansion valve, the refrigeration cycle device comprising: a step in which the control device performs a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator; and a step in which the control device compares a detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation. (15) A control method for a refrigeration cycle apparatus, comprising: when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, the control device controls a second expansion valve disposed between the outdoor heat exchanger and the heat storage heat exchanger to an open state so that the refrigerant flowing out of the outdoor heat exchanger flows into the heat storage heat exchanger. (16) A control method for a refrigeration cycle apparatus, comprising: when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, the control device controls a second expansion valve disposed between the outdoor heat exchanger and the heat storage heat exchanger to an open state so that the refrigerant flowing out of the outdoor heat exchanger flows into the heat storage heat exchanger. (17) A control method for a refrigeration cycle apparatus, comprising: when the control device controls the second expansion valve to an open state, the control device controls an opening degree of the second expansion valve to be smaller than an opening degree of a first expansion valve disposed between the outdoor heat exchanger and the indoor heat exchanger. (18) A control method for a refrigeration cycle apparatus, (17) The control method for a refrigeration cycle device described in (16) above, characterized in that after the control device compares the detection value of the heat storage temperature sensor with the detection value of the refrigerant temperature sensor during the cooling operation, the control device controls the second expansion valve to a closed state when the control device determines that the difference between the detection value of the heat storage temperature sensor and the detection value of the refrigerant temperature sensor has reached a predetermined value.

[0148] DESCRIPTION OF SYMBOLS 1: Compressor, 2: Indoor heat exchanger, 3: Outdoor heat exchanger, 4: Heat storage heat exchanger, 5: Expansion valve, 51: First expansion valve, 52: Second expansion valve, 53: Third expansion valve, 6: Switching valve, 61: First switching valve, 62: Second switching valve, 7: Control device, 71: Temperature detection unit, 72: Memory unit, 72: Determination unit, 74: Switching control unit, C: Refrigerant circuit, HS: Heat storage temperature sensor, RS: Refrigerant temperature sensor, S: Refrigeration cycle device

Claims

a heat storage temperature sensor for detecting the temperature of the heat storage material; and a control device for controlling the switching valve and the expansion valve, wherein the switching valve switches the flow path between a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, and a heat storage cooling operation in which at least the indoor heat exchanger functions as an evaporator when the heat storage heat exchanger functions as a condenser, and wherein the control device controls the switching valve to switch from the cooling operation to the heat storage cooling operation when the control device determines that the detection value of the heat storage temperature sensor has become lower than a first predetermined temperature during the cooling operation.

2. The refrigeration cycle device of claim 1, characterized in that the control device controls the switching valve to switch from the heat storage cooling operation to the cooling operation when it determines that the temperature of the heat storage material detected by the heat storage temperature sensor has reached a second predetermined temperature or higher.

3. The refrigeration cycle device of claim 1, characterized in that the expansion valve is arranged between the outdoor heat exchanger and the indoor heat exchanger, and the amount of refrigerant flowing into the indoor heat exchanger is adjusted by the control device during the heat storage cooling operation.

4. The refrigeration cycle device according to claim 1, wherein the control device controls the switching valve so as to switch from the cooling operation to the heat-storage cooling operation when the thermostat is off during the cooling operation.

5. A refrigeration cycle device according to any one of claims 1 to 4, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.

6. A refrigeration cycle device comprising: 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 refrigerant circuit having a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the changeover valve and the expansion valve, wherein the control device, during cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, determines that the detected value of the heat storage temperature sensor has become lower than a first predetermined temperature, and controls the second expansion valve disposed between the outdoor heat exchanger and the heat storage heat exchanger to open so that the refrigerant flowing out of the outdoor heat exchanger flows into the heat storage heat exchanger.

7. A refrigeration cycle device as described in claim 6, characterized in that when the control device controls the second expansion valve to an open state, the opening degree of the second expansion valve is controlled to be smaller than the opening degree of the first expansion valve arranged between the outdoor heat exchanger and the indoor heat exchanger.

8. A refrigeration cycle device according to claim 6 or 7, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.

9. The refrigeration cycle device described in claim 8, characterized in that the control device controls the second expansion valve to a closed state when it determines that the difference between the detected value of the heat storage temperature sensor and the detected value of the refrigerant temperature sensor has reached a predetermined value.

10. A refrigeration cycle device comprising: 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates; a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the switching valve and the expansion valve, the refrigeration cycle device comprising: a step of performing a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator; and a step of the control device comparing a detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation. a step of controlling the switching valve by the control device to switch from the cooling operation to a heat storage cooling operation in which at least the indoor heat exchanger functions as an evaporator when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, when the control device makes a judgment that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, and 11. A control method for a refrigeration cycle device as described in claim 10, characterized in that after the step of the control device comparing the detected value of the heat storage temperature sensor with the first predetermined temperature during the cooling operation, if the control device determines that the temperature of the heat storage material detected by the heat storage temperature sensor has reached or exceeded a second predetermined temperature, the control device controls the switching valve to switch from the heat storage cooling operation to the cooling operation.

12. The method for controlling a refrigeration cycle device according to claim 10, wherein, when the thermostat is off during the cooling operation, the control device controls the switching valve to switch from the cooling operation to the heat storage cooling operation.

13. A method for controlling a refrigeration cycle device according to any one of claims 10 to 12, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.

14. A refrigeration cycle device comprising: 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 refrigerant circuit having an expansion valve with an adjustable opening and a switching valve that switches a flow path when the refrigerant circulates; a heat storage temperature sensor that detects the temperature of the heat storage material; and a control device that controls the switching valve and the expansion valve, wherein the control device performs a cooling operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator; and a step in which the control device compares the detected value of the heat storage temperature sensor with a first predetermined temperature during the cooling operation. a step in which, when the control device determines that the detected value of the heat storage temperature sensor has become lower than the first predetermined temperature, the control device controls a second expansion valve arranged between the outdoor heat exchanger and the heat storage heat exchanger to an open state so that the refrigerant flowing out of the outdoor heat exchanger flows into the heat storage heat exchanger.

15. A control method for a refrigeration cycle device as described in claim 14, characterized in that when the control device controls the second expansion valve to an open state, the opening degree of the second expansion valve is controlled to be smaller than the opening degree of a first expansion valve arranged between the outdoor heat exchanger and the indoor heat exchanger.

16. A method for controlling a refrigeration cycle device according to claim 14 or 15, wherein the first predetermined temperature is a value detected by a refrigerant temperature sensor.

17. A control method for a refrigeration cycle device as described in claim 16, characterized in that after the step of the control device comparing the detection value of the heat storage temperature sensor with the detection value of the refrigerant temperature sensor during the cooling operation, the control device performs a step of controlling the second expansion valve to a closed state when it is determined by the control device that the difference between the detection value of the heat storage temperature sensor and the detection value of the refrigerant temperature sensor has reached a predetermined value.

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