Refrigeration cycle device and method for controlling refrigeration cycle device

Abstract

Provided are a refrigeration cycle device and a method for controlling the refrigeration cycle device that make it possible to suppress a decrease in comfort for a user even when an operation mode is switched. In the present invention, a refrigerant circuit (C) in which a refrigerant is circulated is connected with: a compressor (1) that compresses the refrigerant; an indoor heat exchanger (2) that exchanges heat between indoor air and the refrigerant; an indoor fan (21) that allows the indoor air to pass through the indoor heat exchanger (2); an outdoor heat exchanger (3) that exchanges heat between outdoor air and the refrigerant; a heat storage heat exchanger (4) that exchanges heat between a heat storage material and the refrigerant; and a plurality of switching valves (6) that each switch a circulation path of the refrigerant in the refrigerant circuit (C) according to a heating operation in which at least the indoor heat exchanger (2) functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger (3) functions as a condenser. The present invention comprises a control device (7) which controls the indoor fan (21) and the switching valves (6). The control device (7) switches between the heating operation and the defrosting operation, and changes the rotational speed of the indoor fan.

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 the refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger, causing the outdoor heat exchanger to function as a condenser and melting the frost. During defrosting operation, the high-temperature refrigerant supplied to the outdoor heat exchanger for defrosting is cooled by melting the frost, and the low-temperature refrigerant flows into the indoor heat exchanger.

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

[0005] One possible method is to continue the heating operation during the defrosting operation by using the heat stored in the heat storage device for defrosting (hereinafter, such an operating mode will be referred to as "defrosting heating operation" where appropriate). This method prevents a drop in the indoor temperature caused by the heating operation being temporarily stopped for the defrosting operation, thereby maintaining user comfort.

[0006] JP 2016-017738 A

[0007] In an air conditioner equipped with such a heat storage device, for example, when switching from heat storage heating operation to defrosting heating operation, the heat exchanger that serves as the condenser is partially changed. That is, in heat storage heating operation, the indoor heat exchanger and the heat exchanger of the heat storage device serve as condensers, and the outdoor heat exchanger serves as an evaporator. In contrast, in defrosting heating operation, the indoor heat exchanger and the outdoor heat exchanger serve as condensers, and the heat exchanger of the heat storage device serves as an evaporator.

[0008] Therefore, when the operation mode is changed from the heat storage heating mode to the defrosting and heat storage mode, the internal volume of the refrigerant flow path of the heat exchanger, which functions as a condenser, increases. This will be explained with reference to Fig. 11. Fig. 11 is an explanatory diagram showing an example of the change in the internal volume of the refrigerant flow path of the heat exchanger when the operation mode is changed in the refrigeration cycle apparatus.

[0009] 11, two graphs are shown, one above the other and one below the large downward arrow in the center of the drawing. The upper graph shows the internal volume of the refrigerant flow path of the heat exchanger that serves as a condenser and an evaporator during heat storage heating operation. On the other hand, the lower graph shows the internal volume of the refrigerant flow path of the heat exchanger that serves as a condenser and an evaporator during defrost heating operation.

[0010] In each graph, the vertical axis indicates the "heat exchanger functioning as a condenser" in the upper row and the "heat exchanger functioning as an evaporator" in the lower row, while the horizontal axis indicates the "internal volume of the refrigerant flow path."

[0011] Furthermore, each graph shows the internal volume of the refrigerant flow path of three types of heat exchangers that make up the air conditioner: the indoor heat exchanger, the outdoor heat exchanger, and the heat exchanger of the heat storage device (represented as the "heat storage heat exchanger" in Figure 11).

[0012] As mentioned above, the horizontal axis of the graph represents the internal volume of the refrigerant flow path, and the internal volume of the refrigerant flow path of each heat exchanger is shown extending from left to right on the graph. For example, the upper part of Figure 11 shows the internal volume of the refrigerant flow path of each heat exchanger during heat storage heating operation. During heat storage heating operation, the "indoor heat exchanger" and the "heat storage heat exchanger" function as condensers, while the "outdoor heat exchanger" functions as an evaporator.

[0013] Therefore, in the graph shown at the top of Fig. 11, the section for "heat exchangers functioning as condensers" shows the internal volumes of the refrigerant flow paths of the "indoor heat exchanger" and the "thermal storage heat exchanger." In contrast, the section for "heat exchangers functioning as evaporators" shows the internal volume of the refrigerant flow path of the "outdoor heat exchanger."

[0014] 11, it can be seen that the internal volume of the refrigerant flow path of the heat exchanger that functions as a condenser is the internal volume of the refrigerant flow path of the indoor heat exchanger plus the internal volume of the refrigerant flow path of the heat storage heat exchanger. On the other hand, since only the outdoor heat exchanger functions as an evaporator, the internal volume of the refrigerant flow path of the heat exchanger that functions as an evaporator is equal to the internal volume of the refrigerant flow path of the outdoor heat exchanger.

[0015] When the internal volume of the refrigerant flow path of the heat exchanger acting as a condenser is compared with the internal volume of the refrigerant flow path of the heat exchanger acting as an evaporator, it is found that the internal volume of the refrigerant flow path of the condenser is larger than the internal volume of the refrigerant flow path of the heat exchanger acting as an evaporator. In this state, when the air conditioner switches from heat storage heating operation to defrost heating operation, the heat exchanger acting as the condenser changes from the heat storage heating operation, and therefore the internal volume of the refrigerant flow path of the heat exchanger acting as a condenser and the internal volume of the refrigerant flow path of the heat exchanger acting as an evaporator change.

[0016] As described above, the lower graph in Figure 11 shows the internal volume of the refrigerant flow path of each heat exchanger during defrosting heating operation. When defrosting heating operation is performed, the heat exchangers that function as condensers are the indoor heat exchanger and the outdoor heat exchanger. Meanwhile, the only heat exchanger that functions as an evaporator is the heat storage heat exchanger. Looking at the internal volumes of the refrigerant flow paths in each case, it can be seen that the internal volume of the refrigerant flow path of the heat exchanger that functions as a condenser is much larger than the internal volume of the refrigerant flow path of the heat exchanger that functions as an evaporator.

[0017] When comparing the internal volume of the refrigerant flow path of the heat exchanger that acts as a condenser during heat storage heating operation with the internal volume of the refrigerant flow path of the heat exchanger that acts as a condenser during defrost heating operation, the internal volume of the refrigerant flow path of the heat exchanger that acts as a condenser is larger than that of the former by the amount indicated by arrow A.

[0018] As shown in Figure 11, for example, when switching from heat storage heating operation to defrost heating operation, the internal volume of the refrigerant flow path of the heat exchanger, which functions as a condenser, increases suddenly. When the internal volume of the refrigerant flow path increases due to this change in operating mode, the amount of high-density liquid-phase refrigerant in the condenser increases, and the pressure of the refrigerant flowing inside the refrigerant circuit decreases as the refrigerant volume decreases. When the refrigerant pressure decreases, the condensing temperature in the condenser also decreases.

[0019] This will be explained with reference to Fig. 12. Fig. 12 is a graph showing the relationship between the rotation speed of the indoor fan and the condensing temperature when the indoor fan is controlled while changing the operating mode in a conventional refrigeration cycle device.

[0020] In Figure 12, the horizontal axis represents time, and the operating mode is switched at a certain time on the horizontal axis. Here, the operating mode before the switch is heat storage heating operation, and the operating mode after the switch is defrost heating operation. Of the lines extending from left to right on the graph over time, the upper solid line represents the rotation speed (air volume) of the indoor fan installed in the indoor unit. Meanwhile, the lower dashed line represents the condensing temperature.

[0021] When the operating mode is switched from the heat storage heating operation to the defrost heating operation, the internal volume of the refrigerant flow path of the heat exchanger that functions as a condenser increases, as shown in Fig. 11. This causes the pressure of the refrigerant flowing in the refrigerant circuit to decrease, and the condensation temperature also decreases. This is indicated by the fact that the condensation temperature, shown by the dashed line in Fig. 12, decreases once the operating mode is switched.

[0022] On the other hand, because the indoor fan speed is controlled based on setting information input via a remote control or the suction temperature, the indoor fan speed does not change immediately even when the operation mode is switched from heat storage heating operation to defrost heating operation. Specifically, the indoor fan speed does not decrease until the condensation temperature falls below a predetermined condensation temperature value at which cool air is felt, so the indoor fan speed does not follow the decrease in condensation temperature. As a result, the indoor fan continues to rotate at the same speed as in heat storage heating operation for a while, causing cool air to be supplied to the room.

[0023] Whether the indoor heat exchanger is in heat storage heating mode or defrost heating mode, it still functions as a condenser, and when the condensation temperature drops as a result of the change in operating mode, cold air is supplied to the heated room. This supply of cold air to the room can reduce user comfort, especially during heating mode.

[0024] 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 suppress a decrease in comfort for the user even when the operating mode is switched.

[0025] A refrigeration cycle device according to one aspect of the present invention includes a refrigerant circuit that circulates the refrigerant, and is connected to the following: a compressor that compresses the refrigerant; an indoor heat exchanger that exchanges heat between indoor air and the refrigerant; an indoor fan that passes the indoor air through the indoor heat exchanger; 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; and a plurality of switching valves that switch the refrigerant circulation path in the refrigerant circuit between a heating operation in which at least the indoor heat exchanger functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser; and a control device that controls the indoor fan and the switching valves, and the control device switches between the heating operation and the defrosting operation and changes the rotation speed of the indoor fan.

[0026] In addition, according to one aspect of the present invention, there is provided a control method for a refrigeration cycle device, the control device comprising: a refrigerant circuit that circulates the refrigerant; a compressor that compresses the refrigerant; an indoor heat exchanger that exchanges heat between indoor air and the refrigerant; an indoor fan that passes the indoor air through the indoor heat exchanger; 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; and a plurality of switching valves that switch the refrigerant circulation path in the refrigerant circuit between a heating operation in which at least the indoor heat exchanger functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser; and a control device that controls the indoor fan and the switching valves, the control device comprising the steps of: determining whether to switch the operation mode between the heating operation and the defrosting operation; switching the switching valve when it is determined that the operation mode should be switched; and controlling the rotation speed of the indoor fan to change in accordance with the operation mode after the switching.

[0027] According to the present invention, even if the driving mode is switched, a decrease in comfort for the user can be suppressed.

[0028] FIG. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of a control device in the refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the rotation speed of the indoor fan and the condensation temperature when the indoor fan is controlled when the operation mode is changed in the refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to an embodiment of the present invention performs cooling operation. FIG. 5 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to an embodiment of the present invention performs heat storage heating operation. FIG. 6 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to an embodiment of the present invention performs defrost heating operation. FIG. 7 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to an embodiment of the present invention performs heat storage heating operation. FIG. 8 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus according to an embodiment of the present invention performs normal heating operation. FIG. 9 is a flowchart showing the control flow when the operation mode is changed in the refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 10 is an explanatory diagram showing an example of a change in the internal volume of the refrigerant flow path of the heat exchanger when the operation mode is changed in the refrigeration cycle apparatus. FIG. 11 is a graph showing the relationship between the rotation speed of the indoor fan and the condensation temperature when the indoor fan is controlled when the operation mode is changed in a conventional refrigeration cycle apparatus.

[0029] The structure of a refrigeration cycle apparatus S according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus S according to the embodiment of the present invention. The refrigeration cycle apparatus S includes a refrigerant circuit C that connects a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4, expansion valves 5 (51, 52, 53), and switching valves 6 (61, 62) and circulates a refrigerant. The refrigeration cycle apparatus S also includes a control device 7 that controls the expansion valve 5 and the switching valve 6.

[0030] 1, a refrigerant circuit C of a refrigeration cycle apparatus S according to an embodiment of the present invention will be described. The refrigerant circuit C is composed of the above-described compressor 1 and other components and refrigerant flow paths connecting these components. For example, when the refrigeration cycle apparatus S performs normal heating operation (described later), the refrigerant discharged from the compressor 1 flows through the indoor heat exchanger 2 and the outdoor heat exchanger 3, and is then drawn into the compressor 1. During heating operation, a first switching valve 61 is provided in the flow path connecting the compressor 1 and the indoor heat exchanger 2, and a third expansion valve 53 is provided in the flow path connecting the indoor heat exchanger 2 and the outdoor heat exchanger 3.

[0031] Furthermore, a first expansion valve 51 and a second switching valve 62 are provided in this order in the flow path connecting the compressor 1 and the heat-storage heat exchanger 4 during the heat-storage heating operation. A second expansion valve 52 is provided in the flow path connecting the heat-storage heat exchanger 4 and the junction C1. Therefore, for example, when the refrigeration cycle apparatus S performs the heat-storage heating operation described below, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 and the heat-storage heat exchanger 4. The refrigerant flowing out of the heat-storage heat exchanger 4 flows to the outdoor heat exchanger 3 via the second expansion valve 52 and the junction C1 provided in the flow path between the second expansion valve 52 and the outdoor heat exchanger 3, and is then drawn into the compressor 1.

[0032] The first switching valve 61 is controlled by a control device 7 (described later) to switch between flowing the refrigerant discharged from the compressor 1 to the indoor heat exchanger 2 and flowing the refrigerant to a bypass circuit B1 connected to a flow path between the first expansion valve 51 and the second switching valve 62. The bypass circuit B1 is provided between the first switching valve 61 and the second switching valve 62. The bypass circuit B1 is provided with a check valve or the like to allow the refrigerant to flow only in the direction of the arrow as shown in FIG.

[0033] As described above, the bypass circuit B1 in the refrigerant circuit C shown in Fig. 1 is provided with a check valve so that the refrigerant flows only in the direction of the arrow. However, it is also possible to use an on-off valve such as a solenoid valve instead of the check valve in the bypass circuit B1. By using an on-off valve in this way, it is possible to flow the refrigerant from the second selector valve 62 to the first selector valve 61, as in the thermal storage heating operation described below.

[0034] When the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2, the bypass circuit B1 is connected to the suction side of the compressor 1. On the other hand, when the refrigerant discharged from the compressor 1 flows into the bypass circuit B1 that is connected to the flow path between the first expansion valve 51 and the second switching valve 62, the indoor heat exchanger 2 is connected to the suction side of the compressor 1 except in the case of the heat storage heating operation.

[0035] The second switching valve 62 is controlled by the control device 7 to switch between flowing the refrigerant discharged from the compressor 1 to the heat storage heat exchanger 4 and flowing it to the outdoor heat exchanger 3. When the refrigerant discharged from the compressor 1 flows to the heat storage heat exchanger 4, the outdoor heat exchanger 3 is connected to the suction side of the compressor 1. On the other hand, when the refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3, the heat storage heat exchanger 4 is connected to the suction side of the compressor 1.

[0036] 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.

[0037] In this embodiment of the present invention, the indoor heat exchanger 2 is provided with an indoor fan 21 that passes indoor air through the indoor heat exchanger 2. In addition, the outdoor heat exchanger 3 is provided with an outdoor fan 31 that passes outdoor air through the outdoor heat exchanger 3.

[0038] 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.

[0039] The heat storage material may be liquid or solid, as long as it can store heat by exchanging heat with the refrigerant flowing inside the heat storage heat exchanger 4. Therefore, for example, if the heat storage material is liquid, the heat storage heat exchanger 4 is immersed in the heat storage material filled in a heat storage container. In other words, the heat storage heat exchanger 4 is surrounded by the heat storage material. The heat supplied from the refrigerant is stored in this heat storage material, and the stored heat is used, for example, for defrosting heating operation or heat storage heating operation, as described below.

[0040] The volume of the heat transfer pipes (from the inlet to the outlet) through which the refrigerant flows in a heat exchanger is referred to as the "internal volume of the refrigerant flow path," and the internal volume of the refrigerant flow path of the heat storage heat exchanger 4 is smaller than the internal volume of the refrigerant flow path of the outdoor heat exchanger 3. This is because the refrigerant exchanges heat with the heat storage material in the heat storage heat exchanger 4, and the refrigerant exchanges heat with the outside air in the outdoor heat exchanger 3.

[0041] In other words, the specific heat of the heat storage material is greater than that of air when heat is exchanged with the refrigerant. Furthermore, the amount of heat exchange is proportional to the temperature difference, i.e., the larger the temperature difference, the greater the heat exchange amount. Therefore, the heat storage heat exchanger 4, which can more easily ensure a temperature difference, can maintain heat exchange performance even if it is smaller than the outdoor heat exchanger 3. Therefore, the internal volume of the refrigerant flow path of the heat storage heat exchanger 4 is smaller than the internal volume of the refrigerant flow path of the outdoor heat exchanger 3.

[0042] The refrigeration cycle apparatus S according to the embodiment of the present invention is provided with a plurality of expansion valves 5. 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.

[0043] The second expansion valve 52 is provided between the heat storage heat exchanger 4 and the above-mentioned confluence C1 in the refrigerant circuit C. That is, the second expansion valve 52 is provided downstream in the direction of refrigerant flow when the heat storage heat exchanger 4 functions as a condenser. The third expansion valve 53 is provided in a flow path connecting the indoor heat exchanger 2 and the outdoor heat exchanger 3. That is, the third expansion valve 53 is provided downstream in the direction of refrigerant flow when the indoor heat exchanger 2 functions as a condenser.

[0044] As described above, the switching valve 6 is composed of the first switching valve 61 and the second switching valve 62. The first switching valve 61 is provided between the compressor 1 and the indoor heat exchanger 2. The second switching valve 62 is provided between the compressor 1 and the outdoor heat exchanger 3 or the thermal storage heat exchanger 4.

[0045] The first switching valve 61 switches the refrigerant between flowing through the indoor heat exchanger 2 and flowing through the bypass circuit B1. On the other hand, the second switching valve 62 switches the refrigerant between flowing through the heat storage heat exchanger 4 and flowing through the outdoor heat exchanger 3.

[0046] In the following description, these three expansion valves 51, 52, and 53 will be referred to as "expansion valve 5" when collectively described, and will be referred to by their respective names when individually described. Similarly, when the two switching valves 61 and 62 are collectively described, they will be referred to as "switching valve 6" when collectively described, and will be referred to by their respective names when individually described.

[0047] Furthermore, in the refrigeration cycle device S according to the embodiment of the present invention, the heating operation is not stopped even when the defrosting operation is performed on the outdoor heat exchanger 3, and a defrosting heating operation is performed in parallel with the defrosting operation.

[0048] The control device 7 controls the opening degrees of the plurality of expansion valves 5. The control device 7 controls the opening degrees of each expansion valve, thereby adjusting the flow rate of the refrigerant flowing through the refrigerant circuit C. As described above, the control device 7 switches the flow of the refrigerant circulating through the refrigerant circuit C by switching the plurality of switching valves 6.

[0049] In this way, the control device 7 performs, for example, a heating and heat storage operation in which a heating operation and a heat storage operation are performed in parallel by controlling the multiple expansion valves 5 and the multiple switching valves 6. The control device 7 also controls, for example, a defrosting operation for the outdoor heat exchanger 3 that is performed in parallel with the heating operation.

[0050] Furthermore, for example, when the operation is switched from heat storage heating operation to defrost heating operation, the control device 7 controls the above-mentioned multiple expansion valves 5 and switching valve 6, and also controls the change in the rotation speed of the indoor fan 21.

[0051] Next, the control by the control device 7 will be described in more detail. As described above, for example, when the operating mode is switched from heat storage heating operation to defrost heating operation, the internal volume of the refrigerant flow path of the heat exchanger that functions as a condenser increases. As a result, the pressure of the refrigerant flowing through the refrigerant circuit decreases, and the condensation temperature also decreases. However, with the conventional method of controlling the indoor fan 21, the rotation speed of the indoor fan 21 does not decrease until the condensation temperature falls below a predetermined condensation temperature value at which the user feels cool air.

[0052] In this way, since the rotation speed of the indoor fan 21 is not changed in accordance with the decreased condensation temperature, the rotation speed of the indoor fan does not follow the decrease in the condensation temperature. Therefore, even when the operation mode is switched from the heat storage heating operation to the defrost heating operation, the indoor fan continues to rotate at the rotation speed during the heat storage heating operation for a while, and cool air continues to be supplied into the room.

[0053] Therefore, in the control device 7 according to the embodiment of the present invention, when the operating state of the refrigeration cycle device S is switched from the heat storage heating operation to the defrost heating operation, the rotation speed of the indoor fan 21 is controlled so as to be an appropriate rotation speed.

[0054] 2 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 determination unit 71, a storage unit 72, a calculation unit 73, and a switching control unit 74.

[0055] The determination unit 71 determines whether to switch between various operation modes such as cooling operation, heat storage heating operation, defrost heating operation, etc. Furthermore, for example, when the operation mode is switched from heat storage heating operation to defrost heating operation, the determination unit 71 controls the rotation speed of the indoor fan 21.

[0056] The storage unit 72 stores at least information relating to the internal volumes of the refrigerant flow paths of the indoor heat exchanger 2, the outdoor heat exchanger 3, and the heat storage heat exchanger 4. The information relating to the internal volumes of the refrigerant flow paths stored in the storage unit 72 may be stored in the storage unit 72 in any manner, for example, by storing the information in a table in which each heat exchanger and the internal volume of each refrigerant flow path are linked to each other.

[0057] The calculation unit 73 calculates the sum of the internal volumes of all the condenser refrigerant flow paths of the heat exchangers functioning as condensers in each operating mode, based on the information on the internal volumes of the refrigerant flow paths stored in the storage unit 72. The sum of the internal volumes of the condenser refrigerant flow paths may be stored in advance in the storage unit 72. When the operating mode is switched, the switching control unit 74 controls the opening degree of the expansion valve 5 and the switching valve 6 based on instructions from the determination unit 71. The switching control unit 74 also switches the rotation speed of the indoor fan 21 in accordance with the switch of the operating mode.

[0058] Next, the function of each part of the control device 7 in this embodiment of the present invention will be described in more detail. When the operating mode is switched to the defrosting heating operation, the previous operating mode can be the heat storage heating operation, the heat storage heating operation, or the normal heating operation, as will be described later. Therefore, the following description will be given taking the case where the operating mode is switched from the heat storage heating operation to the defrosting heating operation as an example.

[0059] The determination unit 71 determines whether to switch the operating state from the heat-storage heating operation to the defrosting heating operation when the refrigeration cycle apparatus S is performing the heat-storage heating operation. That is, for example, when the heat-storage heating operation is being performed, the determination unit 71 determines whether a condition for starting the defrosting heating operation, which indicates that the defrosting heating operation is necessary, is satisfied.

[0060] Here, the condition for starting the defrosting heating operation can be, for example, the evaporation temperature of the refrigerant in the outdoor heat exchanger 3. In other words, if the evaporation temperature is equal to or lower than a preset temperature, there is a possibility of frost forming on the outdoor heat exchanger 3. Therefore, the determination unit 71 determines the start of the defrosting heating operation based on the evaporation temperature of the outdoor heat exchanger 3 during the heat storage heating operation.

[0061] When the determination unit 71 determines that the conditions for starting the defrosting heating operation are satisfied, it instructs the switching control unit 74 to switch the switching valve 6. That is, the second switching valve 62 is switched to switch the operating mode from the heat storage heating operation in which the indoor heat exchanger 2 and the heat storage heat exchanger 4 function as condensers and the outdoor heat exchanger 3 functions as an evaporator to the defrosting heating operation in which the indoor heat exchanger 2 and the outdoor heat exchanger 3 function as condensers and the heat storage heat exchanger 4 functions as an evaporator.

[0062] Additionally, the determination unit 71 sets the rotation speed of the indoor fan 21 after the operation mode is switched from the heat storage heating operation to the defrost heating operation in order to perform control to change the rotation speed of the indoor fan 21 .

[0063] As explained using Figure 11, when the operating mode is switched from heat storage heating operation to defrost heating operation, the heat exchanger that plays the role of the condenser changes from the heat storage heat exchanger 4 to the outdoor heat exchanger 3 (the indoor heat exchanger 2 continues to function as a condenser), and the amount of high-density liquid-phase refrigerant in the condenser increases. Therefore, the pressure of the refrigerant flowing inside the refrigerant circuit decreases as the refrigerant volume decreases. When the refrigerant pressure decreases, the condensing temperature in the condenser also decreases.

[0064] In this case, if the indoor fan 21 is unable to keep up with the drop in condensation temperature and continues to blow air into the room at the same rotation speed as during heat storage heating operation, cold air will be supplied to the heated room. Therefore, in order to avoid supplying cold air into the room in this way from the perspective of maintaining user comfort, the rotation speed of the indoor fan 21 is set as described below.

[0065] First, the determination unit 71 issues an instruction to the calculation unit 73 to calculate the rotation speed of the indoor fan 21 after the operation mode is switched to the defrosting heating operation. Based on the instruction from the determination unit 71 and information related to the internal volume of the refrigerant flow path stored in the storage unit 72, the calculation unit 73 calculates the internal volume of the refrigerant flow path of the heat exchanger functioning as a condenser in each operation mode.

[0066] Here, "information related to the internal volume of the refrigerant flow path" may include, for example, information about the internal volume of the refrigerant flow path of each of the indoor heat exchanger 2, the outdoor heat exchanger 3, and the heat storage heat exchanger 4. In addition, the information may include information about the internal volume of the refrigerant flow path of the entire condenser in a combination of heat exchangers that function as a condenser in each operating mode, and information such as the rotation speed of the indoor fan 21 linked to the combination of heat exchangers (operating mode).

[0067] For example, in the case of the heat storage heating operation, the condensers are the indoor heat exchanger 2 and the heat storage heat exchanger 4. Therefore, the calculation unit 73 first calculates the internal volumes of the refrigerant flow paths of these heat exchangers that function as condensers in the heat storage heating operation.

[0068] In addition, the internal volumes of the refrigerant flow paths of the heat exchangers that function as condensers in the defrosting heating operation, which is the operating mode after the switchover, are calculated. In the defrosting heating operation, the indoor heat exchanger 2 and the outdoor heat exchanger 3 function as condensers, so the sum of the internal volumes of the refrigerant flow paths of these condensers is calculated.

[0069] The calculation unit 73 then calculates the rate of change in the internal volume of the condenser refrigerant flow path before and after the switching of the operating mode. This rate of change is the value of the internal volume of the condenser refrigerant flow path after the switching (the sum of the internal volume of the refrigerant flow path of the indoor heat exchanger 2 and the internal volume of the refrigerant flow path of the heat storage heat exchanger 4) relative to the internal volume of the condenser refrigerant flow path before the switching of the operating mode (the sum of the internal volume of the refrigerant flow path of the indoor heat exchanger 2 and the internal volume of the refrigerant flow path of the heat storage heat exchanger 4).

[0070] The calculation unit 73 then sets the rotation speed of the indoor fan 21 in the operating mode after the switch (here, defrosting and heating operation) based on the value obtained by multiplying the calculated rate of change by the rotation speed of the indoor fan 21 in the operating mode before the switch (here, defrosting and heating operation).

[0071] In this way, the determination unit 71 can adopt a method of setting the rotation speed of the indoor fan 21 after the operation mode is switched based on the rate of change calculated by the calculation unit 73. In addition to this, for example, the following method can also be adopted.

[0072] That is, when the judgment unit 71 determines that the conditions for starting defrost heating operation are met, the judgment unit 71 accesses the memory unit 72 and obtains information regarding the internal volume of the refrigerant flow path of each heat exchanger stored in the memory unit 72.

[0073] As described above, information about the internal volume of the refrigerant flow path of the entire condenser in the combination of heat exchangers that function as condensers in each operating mode is stored in the memory unit 72. The determination unit 71 accesses the memory unit 72 to obtain information about the internal volume of the refrigerant flow path from the memory unit 72, and sets the rotation speed of the indoor fan 21 based on the information about the internal volume of the refrigerant flow path.

[0074] Using the method described above, the determination unit 71 sets a new rotation speed of the indoor fan 21. Then, based on the setting, the determination unit 71 instructs the switching control unit 74 to switch the rotation speed of the indoor fan 21.

[0075] The switching control unit 74, for example, switches the switching valve 6 based on an instruction to switch the operation mode from the determination unit 71. Specifically, when the operation mode switches from the heat storage heating operation to the defrost heating operation, the switching control unit 74 switches the second switching valve 62. This allows the refrigerant discharged from the compressor 1, which had been flowing to the heat storage heat exchanger 4 during the heat storage heating operation, to flow to the outdoor heat exchanger 3.

[0076] FIG. 3 is a graph showing the relationship between the rotation speed of the indoor fan 21 and the condensing temperature when the indoor fan 21 is controlled when the operating mode is changed in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0077] In Figure 3, the horizontal axis represents time, and the operating mode is switched at a certain time along the horizontal axis. Here, the operating mode before the switch is heat storage heating operation, and the operating mode after the switch is defrost heating operation. Of the lines extending from left to right on the graph over time, the upper solid line represents the rotation speed (air volume) of the indoor fan installed in the indoor unit. Meanwhile, the lower dashed line represents the condensing temperature.

[0078] As explained above, when the operating mode is switched from the heat storage heating operation to the defrost heating operation, the internal volume of the refrigerant flow path of the heat exchanger that functions as a condenser increases. Therefore, in the conventional control method, the pressure of the refrigerant flowing in the refrigerant circuit decreases, and the condensing temperature also decreases, as shown in Figure 12.

[0079] On the other hand, in this embodiment, as described above, when the operating mode is switched from the heat storage heating operation to the defrost heating operation, the rotation speed of the indoor fan 21 is changed, that is, control is performed to reduce the rotation speed of the indoor fan 21. This control is indicated by the dotted line parallel to the vertical axis in Fig. 3, which shows that the rotation speed of the indoor fan 21 is reduced in accordance with the switching control of the second switching valve 62 by the switching control unit 74.

[0080] By changing the rotation speed of the indoor fan 21 in accordance with the change in the operating mode in this way, it is possible to prevent a large drop in the condensation temperature and to avoid the supply of cold air into the room, thereby maintaining user comfort.

[0081] On the other hand, in the graph of Fig. 3, after the operation mode is switched from the heat storage heating operation to the defrost heating operation, the condensation temperature in the defrost heating operation remains roughly constant, only slightly lower than the condensation temperature in the heat storage heating operation. The rotation speed of the indoor fan 21 is reduced roughly at the same time as the operation mode is switched. As a result, the decrease in the condensation temperature is smaller than when the rotation speed of the indoor fan 21 is reduced some time after the operation mode is switched, as shown in at least Fig. 12.

[0082] The above explanation has been given on the assumption that the heat storage heating operation is being performed as the operating mode before the defrost heating operation is started. However, other than the heat storage heating operation, other heating operation modes such as the heat storage heating operation and the normal heating operation are also possible.

[0083] As explained above, the heat stored in the heat storage heat exchanger 4 during the heat storage heating operation is used during the defrosting operation for the outdoor heat exchanger 3. In contrast, the heat storage heating operation is an operation mode in which the heat stored in the heat storage heat exchanger 4 is used for the heating operation.

[0084] The thermal storage heating operation is an operation mode that is performed to satisfy the required heating capacity by using the heat stored in the thermal storage heat exchanger 4 when, for example, the outdoor temperature is low and heat cannot be taken in by the outdoor heat exchanger 3. In this operation mode, as shown in Fig. 7 described later, only the indoor heat exchanger 2 functions as a condenser, and the thermal storage heat exchanger 4 and the outdoor heat exchanger 3 both function as evaporators.

[0085] Next, normal heating operation is an operation mode in which, when heating operation is performed, refrigerant is not circulated through the heat storage heat exchanger 4. The amount of heat that can be stored in the heat storage heat exchanger 4 is determined by the type and capacity of the heat storage material. Therefore, for example, when heat is stored in the heat storage heat exchanger 4 by performing heat storage heating operation, there may be a case in which the heat storage material cannot store any more heat.

[0086] When the heat storage heat exchanger 4 is in this state, the heat storage effect cannot be expected even if the refrigerant is made to flow into the heat storage heat exchanger 4 to perform heat exchange, and it is therefore not necessary to make the refrigerant flow into the heat storage heat exchanger 4. Therefore, when performing heating operation in this case, the normal heating operation is an operating mode in which the refrigerant is not made to flow into the heat storage heat exchanger 4 but is made to flow only into the outdoor heat exchanger 3.

[0087] Therefore, during normal heating operation, only the indoor heat exchanger 2 functions as a condenser, while the outdoor heat exchanger 3 functions as an evaporator. As shown in Fig. 8, which will be described later, no refrigerant flows into the heat storage heat exchanger 4.

[0088] Even when the operating mode is switched from such heat storage heating operation or from normal heating operation to defrost heating operation, the rotation speed of the indoor fan 21 is set by the control device 7 as described above based on information regarding the internal volume of the refrigerant flow path of the heat exchanger that serves as a condenser.

[0089] It is assumed that the operation mode is switched from the various heating operations described above to the defrosting heating operation. In the defrosting operation without heating operation, there is no possibility that cool air will be supplied to the room by the indoor fan 21. Therefore, even if control to change the rotation speed of the indoor fan 21 is not performed when the condensing temperature drops, the decrease in comfort felt by the user is considered to be less than in the defrosting heating operation.

[0090] The functions of the control device 7 of the refrigeration cycle apparatus S according to the embodiment of the present invention have been described above. Next, the operating modes of the refrigeration cycle apparatus S will be described in order using the circuit diagrams of the refrigeration cycle apparatus S according to the embodiment of the present invention shown in Figures 4 to 8.

[0091] 4 to 8, refrigerant circuits C through which refrigerant actually flows are indicated by solid lines. On the other hand, refrigerant circuits C through which refrigerant does not flow are indicated by dashed lines. The direction of the refrigerant flowing through the refrigerant circuits C is indicated by arrows.

[0092] First, the cooling operation will be described. Fig. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs cooling operation. During cooling operation, the indoor heat exchanger 2 functions as an evaporator, and the outdoor heat exchanger 3 functions as a condenser. On the other hand, no refrigerant flows into the thermal storage heat exchanger 4.

[0093] 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. 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 B1 and flows into the outdoor heat exchanger 3 from the second switching valve 62.

[0094] The refrigerant that has flowed into the outdoor heat exchanger 3 is cooled by the outdoor air that is supplied by the rotation of the outdoor fan 31, and dissipates heat into the outdoor air. Then, a part or all of the refrigerant condenses.

[0095] 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.

[0096] Through heat exchange by the indoor heat exchanger 2, the refrigerant absorbs heat from the indoor air and evaporates, and the indoor air drawn into the indoor heat exchanger 2 is cooled and supplied into the room by the indoor fan 21 to cool the room. The refrigerant that has absorbed heat through heat exchange then flows into the compressor 1 via the first switching valve 61.

[0097] On the other hand, the flow of the refrigerant when the refrigeration cycle apparatus S performs the heat storage heating operation is as shown in Fig. 5. Fig. 5 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 the heat storage heating operation.

[0098] 5, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. In the indoor heat exchanger 2, heat is exchanged between the refrigerant and the air flowing into the indoor unit, and the air that has been heated by absorbing heat from the refrigerant is supplied to the indoor space. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0099] The refrigerant flowing out of the indoor heat exchanger 2 passes through the third expansion valve 53 and flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 passes through the second switching valve 62 and flows into the compressor 1.

[0100] As described above, the refrigeration cycle apparatus S in the embodiment of the present invention is provided with the heat storage heat exchanger 4 in addition to the indoor heat exchanger 2 and the outdoor heat exchanger 3. When the heat storage heating operation is performed, the refrigerant discharged from the compressor 1 not only flows into the indoor heat exchanger 2 as described above, but also branches before reaching the first switching valve 61 and flows into the heat storage heat exchanger 4 via the first expansion valve 51 and the second switching valve 62.

[0101] In the heat storage heat exchanger 4, the refrigerant that has flowed in exchanges heat with a heat storage material, and heat of the refrigerant is stored in the heat storage material. The refrigerant that has flowed out of the heat storage heat exchanger 4 flows into the outdoor heat exchanger 3 via the second expansion valve 52, and then flows out of the outdoor heat exchanger 3 and into the compressor 1 via the second switching valve 62.

[0102] 6 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention is performing defrosting heating operation. The refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. Since the heating operation is performed here, the indoor heat exchanger 2 functions as a condenser, and heat is exchanged between the refrigerant and the air flowing into the indoor unit in the indoor heat exchanger 2, and the heated air is supplied to the indoor space by absorbing heat from the refrigerant.

[0103] Furthermore, the refrigerant discharged from the compressor 1 branches before reaching the first switching valve 61 and flows into the outdoor heat exchanger 3 via the first expansion valve 51 and the second switching valve 62. When the high-temperature refrigerant from the compressor 1 flows into the outdoor heat exchanger 3, a defrosting operation is performed to melt frost that has adhered to the outdoor heat exchanger 3.

[0104] The refrigerant flowing out of the indoor heat exchanger 2 flows into the heat storage heat exchanger 4 via the third expansion valve 53 and the second expansion valve 52. At this time, the third expansion valve 53 and the second expansion valve 52 are fully open. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the heat storage heat exchanger 4 via the second expansion valve 52. In the heat storage heat exchanger 4, heat exchange occurs between the flowing refrigerant and the heat storage material. The refrigerant flowing out of the heat storage heat exchanger 4 flows into the compressor 1 via the second switching valve 62.

[0105] Next, a description will be given of the flow of refrigerant when the refrigeration cycle apparatus S performs the heat storage heating operation. Fig. 7 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S according to the embodiment of the present invention performs the heat storage heating operation.

[0106] 7, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. In the case of the thermal storage heating operation, all of the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2. Therefore, the expansion valve 51 provided in the first circuit that branches off before reaching the first switching valve 61 is controlled by the switching control unit 74 to be fully closed.

[0107] The refrigerant that has flowed into the indoor heat exchanger 2 exchanges heat with the air flowing into the indoor unit, and the air that has absorbed heat from the refrigerant is supplied to the indoor space. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0108] The refrigerant flowing out of the indoor heat exchanger 2 flows into the heat storage heat exchanger 4 via a junction C1 provided in the flow path between the second expansion valve 52 and the outdoor heat exchanger 3. The heat storage heat exchanger 4 functions as an evaporator, and the low-temperature, low-pressure refrigerant that has flowed in exchanges heat with a heat storage material in the heat storage heat exchanger 4. The refrigerant flowing out of the heat storage heat exchanger 4 flows into the compressor 1 via a second switching valve 62.

[0109] The refrigerant flowing out of the indoor heat exchanger 2 passes through the third expansion valve 53 and flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 passes through the second switching valve 62, the bypass circuit B2, and the first switching valve 61 and flows into the compressor 1.

[0110] In the case of the thermal storage heating operation, as described above, the bypass circuit B2 employs an on-off valve instead of a check valve as in the previous bypass circuit B1. This on-off valve allows the refrigerant flowing out of the outdoor heat exchanger 3 to flow from the second selector valve 62 to the first selector valve 61, and can be returned to the compressor 1.

[0111] Finally, a description will be given of the flow of the refrigerant when the refrigeration cycle apparatus S performs normal heating operation. Fig. 8 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 normal heating operation.

[0112] 8, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. In the indoor heat exchanger 2, heat is exchanged between the refrigerant and the air flowing into the indoor unit, and the air that has been heated by absorbing heat from the refrigerant is supplied to the indoor space. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0113] The refrigerant flowing out of the indoor heat exchanger 2 passes through the third expansion valve 53 and flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 passes through the second switching valve 62 and flows into the compressor 1.

[0114] On the other hand, as described above, in normal heating operation, there is no need to flow refrigerant into the heat storage heat exchanger 4, so the first expansion valve 51 is controlled to be fully closed to prevent the refrigerant discharged from the compressor 1 from flowing into the heat storage heat exchanger 4. Therefore, no heat exchange occurs between the heat storage material and the refrigerant in the heat storage heat exchanger 4. In addition, the second expansion valve 52 is also controlled to be fully closed.

[0115] [Operation] Next, the flow of control of the refrigeration cycle apparatus S by the control device 7 when the operation mode is switched from the heat storage heating operation, the heat storage heating operation, or the normal heating operation to the defrosting heating operation will be described with reference to Figures 9 and 10. Figure 9 is a flowchart showing the flow of control when the operation mode is changed in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0116] As mentioned above, there are various types of heating operation, but the following description will be given taking an example in which the operation mode is switched from the heat storage heating operation to the defrosting heating operation as before.

[0117] First, in the refrigeration cycle apparatus S, a heat storage heating operation is started (ST1). The conditions for starting the heat storage heating operation are set in advance, and the control device 7 determines whether or not the conditions are met. For example, a condition for starting the heat storage heating operation is set such that the difference between the heat storage material temperature and the outside air temperature is less than a predetermined value. This allows the heat storage heating operation to be performed when the amount of stored heat is insufficient.

[0118] When the heat storage heating operation starts, as described above, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 through the first switching valve 61, and also flows into the heat storage heat exchanger 4 through the first expansion valve 51 and the second switching valve 62.

[0119] While the heat storage heating operation is being performed, the control device 7 determines whether or not a defrosting operation is required for the outdoor heat exchanger 3 according to a preset condition for transitioning to the defrosting operation (ST2). If the defrosting operation is not required (NO in ST2), the heat storage heating operation continues.

[0120] On the other hand, if the control device 7 (determination unit 71) determines that the conditions for starting defrosting heating operation are met (YES in ST2), a switching process is executed to switch the operating mode from heat storage heating operation to defrosting heating operation (ST3).

[0121] Specifically, the determination unit 71 instructs the switching control unit 74 to switch the second switching valve 62. Based on the instruction, the switching control unit 74 switches the second switching valve 62 so that the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 instead of the heat storage heat exchanger 4 (ST4).

[0122] The determination unit 71 then sets the rotation speed of the indoor fan 21 after the operation mode has been switched (ST5). A detailed flow of the process using the calculation unit 73 to set the rotation speed of the indoor fan 21 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing the control flow when the operation mode has changed in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0123] When the calculation unit 73 receives an instruction from the determination unit 71 to switch the operation mode from the heat storage heating operation to the defrost heating operation, the calculation unit 73 first accesses the memory unit 72 and calculates the sum of the internal volumes of the refrigerant flow paths of all the heat exchangers that function as condensers in the heat storage heating operation (ST51). Since the condensers in the heat storage heating operation are the indoor heat exchanger 2 and the heat storage heat exchanger 4, the calculation unit 73 calculates the sum of the internal volumes of the refrigerant flow paths of these heat exchangers.

[0124] Next, the calculation unit 73 calculates the sum of the internal volumes of the refrigerant flow paths of all heat exchangers that function as condensers in the defrosting heating operation (ST52). Because the condensers in the defrosting heating operation are the indoor heat exchanger 2 and the outdoor heat exchanger 3, the calculation unit 73 calculates the sum of the internal volumes of the refrigerant flow paths of these heat exchangers.

[0125] The calculation unit 73 calculates a rate of change of the internal volume of the refrigerant flow path of the heat exchanger during the heat storage heating operation before the operation mode is switched (the internal volume of the condenser refrigerant flow path before the switching) in the defrosting heating operation after the switching (the internal volume of the condenser refrigerant flow path after the switching) relative to the internal volume of the refrigerant flow path of the heat exchanger during the heat storage heating operation before the switching of the operation mode (ST53).The calculation unit 73 then sets the rotation speed of the indoor fan 21 after the operation mode is switched to the defrosting heating operation based on a value obtained by multiplying the calculated rate of change by the rotation speed of the indoor fan 21 during the operation mode before the switching of the operation mode (here, the defrosting heating operation) (ST54).

[0126] The determination unit 71 sets the rotation speed of the indoor fan 21 calculated by the calculation unit 73 as the rotation speed of the indoor fan 21 in the post-switching operation mode. Then, the determination unit 71 instructs the indoor unit via the switching control unit 74 to drive the indoor fan 21 based on the set rotation speed of the indoor fan 21.

[0127] Instead of the above method, the following method can also be adopted for setting the rotation speed of the indoor fan 21. That is, for example, a method may be adopted in which, when starting the defrosting heating operation, the determination unit 71 acquires information about the internal volume of the refrigerant flow path from the storage unit 72 based on the type of heating operation that was performed before the defrosting heating operation, and sets the rotation speed of the indoor fan 21.

[0128] Then, when the process of switching the operation mode to the defrosting heating operation is completed, the defrosting heating operation is started (ST6 in FIG. 9 ). As described above, in the defrosting heating operation, the heating operation is performed and the defrosting operation is performed using the heat stored in the heat storage heat exchanger 4.

[0129] While the defrosting and heating operation is being performed, the control device 7 determines whether or not to terminate the defrosting and heating operation based on a preset termination condition (ST7).

[0130] If the control device 7 determines not to terminate the defrosting heating operation (NO in ST7), the defrosting heating operation that is currently being performed continues. On the other hand, if the control device 7 determines to terminate the defrosting heating operation (YES in ST7), the defrosting heating operation is terminated (ST8).

[0131] Since the defrosting heating operation has ended, the control device 7 executes the process of switching the operation mode again (ST9). The operation mode to be switched from the defrosting heating operation is not specified here, but the operation mode may be switched to the heat storage heating operation again. Alternatively, the operation mode may be switched to the heat storage heating operation or the normal heating operation based on the user's settings, etc.

[0132] The control device 7 controls the switching valve 6 via the switching control section 74 (ST10), and sets the rotation speed of the indoor fan 21 according to the mode of heating operation (ST11).

[0133] That is, up to now, we have explained the case where the internal volume of the refrigerant flow path of the condenser increases due to a change in the operating mode and the heat exchanger that functions as the condenser. In this case, as described above, the rotation speed of the indoor fan 21 is controlled to decrease. Conversely, when the operating mode changes and the heat exchanger that functions as the condenser decreases the internal volume of the refrigerant flow path of the condenser and the condensing temperature increases, the rotation speed of the indoor fan 21 is controlled to increase.

[0134] Such control is performed, for example, when the operation mode is switched from the defrosting heating operation to the heat storage heating operation. Therefore, in the operation of the refrigeration cycle apparatus S described above, in the switching process when the defrosting heating operation is switched to the heating operation, the rotation speed of the indoor fan 21 is set to be increased.

[0135] In the explanation here, the control of the switching valve 6 and the setting of the rotation speed of the indoor fan 21 are explained first and then the latter. However, this order is explained merely for the convenience of explanation, and the order of the control of the switching valve 6 and the setting of the rotation speed of the indoor fan 21 may be reversed, or both may be performed simultaneously.

[0136] As described above, when the operation mode is switched from heating operation to defrosting heating operation, the rotation speed of the indoor fan 21 is controlled in accordance with the drop in the condensing temperature, thereby preventing a sudden drop or rise in the temperature of the air blown from the indoor unit. Therefore, even when the operation mode is switched, a decrease in comfort for the user can be suppressed.

[0137] In particular, when cool air is supplied to the room due to a drop in the condensation temperature, the decrease in user comfort becomes significant. Therefore, in such cases, it is very effective to control the rotation speed of the indoor fan 21 to be reduced based on the internal volume of the refrigerant flow path of the heat exchanger that serves as a condenser.

[0138] 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.

[0139] 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.

[0140] For example, in the process flow for switching the operation mode described above, when the determination unit 71 determines that the conditions for starting the defrosting heating operation are satisfied, it switches the switching valve 6. In addition to this process, it sets the rotation speed of the indoor fan 21 and instructs the indoor unit to rotate the indoor fan 21 at the set rotation speed.

[0141] However, instead of this processing, for example, when the judgment unit 71 judges that the conditions for starting defrost heating operation are satisfied, the judgment unit 71 first sets the rotation speed of the indoor fan 21 and instructs the indoor unit of the set rotation speed.

[0142] In this case, after this process, the switching valve 6 is controlled, but the rotation speed of the indoor fan 21 is gradually reduced before this control of the switching valve 6 is executed. Then, when the switching valve 6 is actually switched and the defrost heating operation is started, the rotation speed of the indoor fan 21 has already been reduced to the set rotation speed.

[0143] By performing such processing, the timing of switching the operation mode and the timing of the processing for changing the rotation speed of the indoor fan 21 can be more closely matched, which contributes to maintaining comfort for the user even more.

[0144] In addition, it has been described above that the calculation unit 73 calculates the rate of change of the internal volume of the post-switching condenser refrigerant flow path after switching the operation mode relative to the internal volume of the pre-switching condenser refrigerant flow path before switching the operation mode when setting the rotation speed of the indoor fan 21. However, when the calculation unit 73 calculates the rate of change, it may also use, for example, the set temperature of the indoor unit before switching the operation mode and the current room temperature after switching.

[0145] Furthermore, various explanations have been given on the assumption that the refrigeration cycle apparatus S in the embodiment of the present invention includes a refrigerant circuit C in which the indoor heat exchanger 2, the outdoor heat exchanger 3, and the heat storage heat exchanger 4 are connected in parallel. However, the above explanations also apply to the case of a refrigeration cycle apparatus including a refrigerant circuit in which these heat exchangers are connected in series.

[0146] In the above description of the thermal storage heating operation, the case where the outdoor heat exchanger functions as an evaporator in addition to the thermal storage heat exchanger has been described as an example. However, in the thermal storage heating operation, it is also possible to have only the thermal storage heat exchanger function as an evaporator, without necessarily having the outdoor heat exchanger function as an evaporator.

[0147] The techniques described in the embodiments of the present invention may also be configured as follows: (1) A refrigeration cycle apparatus 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 including: a plurality of switching valves that switch a circulation path of the refrigerant between a heating operation in which at least the indoor heat exchanger functions as a condenser and the outdoor heat exchanger functions as an evaporator; and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser; an indoor fan that passes the indoor air through the indoor heat exchanger; and a control device that controls the indoor fan and the switching valve, wherein the control device changes the rotation speed of the indoor fan when switching between the heating operation and the defrosting operation. (2) The refrigeration cycle apparatus according to (1), wherein the control device includes a storage unit that stores information about the internal volumes of the refrigerant flow paths of at least the indoor heat exchanger, the outdoor heat exchanger, and the heat storage heat exchanger, and when the control device performs control to change the rotation speed of the indoor fan, the control device sets the rotation speed of the indoor fan based on the information about the internal volumes of the refrigerant flow paths. (3) The control device further includes a calculation unit that calculates a sum of the internal volumes of all condenser refrigerant flow paths of the heat exchangers that function as condensers in each operating mode based on the information about the internal volumes of the refrigerant flow paths stored in the storage unit, the calculation unit calculates a rate of change of the internal volume of the post-switching condenser refrigerant flow path after switching the operating mode relative to the internal volume of the pre-switching condenser refrigerant flow path before switching the operating mode, and when the control device performs control to change the rotation speed of the indoor fan, the control device sets the rotation speed of the indoor fan after switching the operating mode based on the rate of change.(4) The refrigeration cycle apparatus according to any one of (1) to (3), characterized in that the control device controls to reduce the rotation speed of the indoor fan when switching the switching valve to switch from a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as condensers and the outdoor heat exchanger function as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator. (5) The refrigeration cycle apparatus according to any one of (1) to (3), characterized in that the control device controls to reduce the rotation speed of the indoor fan when switching the switching valve to switch from a heat storage heating operation in which the indoor heat exchanger and the outdoor heat exchanger and the heat storage heat exchanger function as evaporators to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator. (6) The refrigeration cycle device according to any one of (1) to (3), wherein the control device controls the indoor fan to reduce its rotation speed when switching the switching valve from a normal heating operation in which the indoor heat exchanger functions as a condenser and only the outdoor heat exchanger functions as an evaporator to a defrosting heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator. (7) The refrigeration cycle device according to any one of (1) to (6), wherein an internal volume of a refrigerant flow path of the heat storage heat exchanger is smaller than an internal volume of a refrigerant flow path of the outdoor heat exchanger.(8) A control method for a refrigeration cycle device, comprising: a compressor that compresses the 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; and a plurality of switching valves that switch a circulation path of the refrigerant in the refrigerant circuit between a heating operation in which at least the indoor heat exchanger functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser, connected to the refrigeration cycle device; an indoor fan that passes the indoor air through the indoor heat exchanger; and a control device that controls the indoor fan and the switching valve, wherein the control device comprises: a step of determining whether to switch an operation mode between the heating operation and the defrosting operation; a step of switching the switching valve when it is determined that the operation mode should be switched; and a step of controlling to change the rotation speed of the indoor fan in accordance with the operation mode after the rotation speed of the indoor fan is switched. (9) The control method for a refrigeration cycle apparatus according to (8), characterized in that, in the step in which the control device performs control to change the rotation speed of the indoor fan, the rotation speed of the indoor fan is set based on information about at least the internal volumes of the refrigerant flow paths of the indoor heat exchanger, the outdoor heat exchanger, and the heat storage heat exchanger. (10) The control method for a refrigeration cycle apparatus according to (9), characterized in that, in the steps prior to the step in which the control device performs control to change the rotation speed of the indoor fan, the control method includes the steps of: calculating a sum of the internal volumes of all condenser refrigerant flow paths of heat exchangers functioning as condensers in each operating mode based on information about the internal volumes of the refrigerant flow paths; calculating a rate of change in the internal volume of the post-switching condenser refrigerant flow path after switching of the operating mode relative to the internal volume of the pre-switching condenser refrigerant flow path before switching of the operating mode; and setting the rotation speed of the indoor fan after switching of the operating mode based on the rate of change.(11) The control method for a refrigeration cycle device described in any one of (8) to (10) above, characterized in that the step in which the control device performs control to change the rotation speed of the indoor fan is a step in which the control device switches the switching valve to perform control to reduce the rotation speed of the indoor fan when switching from a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as condensers and the outdoor heat exchanger function as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator. (12) The control method for a refrigeration cycle device according to any one of (8) to (10) above, characterized in that the step of the control device performing control to change the rotation speed of the indoor fan is a step of performing control to reduce the rotation speed of the indoor fan when the control device switches the switching valve to switch from a heat storage heating operation in which the indoor heat exchanger functions as a condenser and the outdoor heat exchanger and the heat storage heat exchanger function as evaporators to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator. (13) The control method for a refrigeration cycle device according to any one of (8) to (10), characterized in that the step of the control device performing control to change the rotation speed of the indoor fan is a step of performing control to reduce the rotation speed of the indoor fan when the control device switches the switching valve to switch from a heat storage heating operation in which the indoor heat exchanger functions as a condenser and the outdoor heat exchanger and the heat storage heat exchanger function as evaporators to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator. The control method for a refrigeration cycle device described in (8) above is characterized in that the control device performs control to reduce the rotation speed of the indoor fan when switching from normal heating operation, in which the indoor heat exchanger functions as a condenser and only the outdoor heat exchanger functions as an evaporator, to defrost heating operation, in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator, by switching the switching valve.

[0148] DESCRIPTION OF SYMBOLS 1: Compressor, 2: Indoor heat exchanger, 3: Outdoor heat exchanger, 31: Outdoor fan, 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: Determination unit, 72: Storage unit, 73: Calculation unit, 74: Switching control unit, C: Refrigerant circuit, S: Refrigeration cycle device

Claims

1. A refrigeration cycle device comprising: a compressor for compressing a refrigerant; an indoor heat exchanger for exchanging heat between indoor air and the refrigerant; an outdoor heat exchanger for exchanging heat between outdoor air and the refrigerant; a heat storage heat exchanger for exchanging heat between a heat storage material and the refrigerant; a refrigerant circuit having a plurality of switching valves for switching the circulation path of the refrigerant between a heating operation in which at least the indoor heat exchanger functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser; an indoor fan for passing the indoor air through the indoor heat exchanger; and a control device for controlling the indoor fan and the switching valve, wherein the control device changes the rotation speed of the indoor fan when switching between the heating operation and the defrosting operation.

2. The refrigeration cycle apparatus of claim 1, characterized in that the control device is provided with a memory unit that stores information regarding the internal volume of the refrigerant flow path of each of the indoor heat exchanger and the outdoor heat exchanger, and when the control device controls the indoor fan to change its rotation speed, the control device sets the rotation speed of the indoor fan based on the information regarding the internal volume of the refrigerant flow path.

3. The control device further includes a calculation unit that calculates a sum of the internal volumes of all condenser refrigerant flow paths of the heat exchanger functioning as a condenser in each operating mode based on information regarding the internal volumes of the refrigerant flow paths stored in the memory unit, the calculation unit calculates a rate of change in the internal volume of the post-switching condenser refrigerant flow path after switching to the internal volume of the pre-switching condenser refrigerant flow path before switching the operating mode, and when the control device controls the change in the rotation speed of the indoor fan, it sets the rotation speed of the indoor fan after switching the operating mode based on the rate of change.

4. The refrigeration cycle apparatus of claim 1, characterized in that the control device controls the indoor fan to reduce its rotation speed when switching from a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as condensers and the outdoor heat exchanger function as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator by switching the switching valve.

5. The refrigeration cycle apparatus of claim 1, characterized in that the control device controls the indoor fan to reduce its rotation speed when switching from a heat storage heating operation in which the indoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator by switching the switching valve.

6. The refrigeration cycle device of claim 1, characterized in that the control device controls the indoor fan to reduce its rotation speed when switching from normal heating operation, in which the indoor heat exchanger functions as a condenser and only the outdoor heat exchanger functions as an evaporator, to defrost heating operation, in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator, by switching the switching valve.

7. A refrigeration cycle device according to any one of claims 1 to 6, characterized in that the internal volume of the refrigerant flow path of the heat storage heat exchanger is smaller than the internal volume of the refrigerant flow path of the outdoor heat exchanger.

8. A control method for a refrigeration cycle apparatus, comprising: a compressor for compressing the refrigerant, an indoor heat exchanger for exchanging heat between indoor air and the refrigerant, an outdoor heat exchanger for exchanging heat between outdoor air and the refrigerant, a heat storage heat exchanger for exchanging heat between a heat storage material and the refrigerant, and a plurality of switching valves for switching a circulation path of the refrigerant in the refrigerant circuit between a heating operation in which at least the indoor heat exchanger functions as a condenser and a defrosting operation in which at least the outdoor heat exchanger functions as a condenser, an indoor fan for passing the indoor air through the indoor heat exchanger, and a control device for controlling the indoor fan and the switching valve, wherein the control device comprises: a step of determining whether to switch an operation mode between the heating operation and the defrosting operation; a step of switching the switching valve when it is determined that the operation mode is to be switched; and a step of controlling to change the rotation speed of the indoor fan in accordance with the operation mode after the rotation speed of the indoor fan is switched.

9. A method for controlling a refrigeration cycle device as described in claim 8, characterized in that, in the step in which the control device controls to change the rotation speed of the indoor fan, the rotation speed of the indoor fan is set based on information regarding at least the internal volume of the refrigerant flow path of each of the indoor heat exchanger and the outdoor heat exchanger.

10. A control method for a refrigeration cycle device as described in claim 9, characterized in that, in a step prior to the step in which the control device performs control to change the rotation speed of the indoor fan, the control method includes the steps of: calculating a sum of the internal volumes of all condenser refrigerant flow paths of the heat exchanger functioning as a condenser in each operating mode based on information regarding the internal volumes of the refrigerant flow paths; calculating a rate of change in the internal volume of the post-switching condenser refrigerant flow path after switching to the internal volume of the pre-switching condenser refrigerant flow path before switching the operating mode; and setting the rotation speed of the indoor fan after switching the operating mode based on the rate of change.

11. The control method for a refrigeration cycle apparatus as described in claim 8, characterized in that the step in which the control device performs control to change the rotation speed of the indoor fan is a step in which the control device switches the switching valve to perform control to reduce the rotation speed of the indoor fan when switching from a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as condensers and the outdoor heat exchanger function as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger function as an evaporator.

12. A control method for a refrigeration cycle apparatus as described in claim 8, characterized in that the step in which the control device performs control to change the rotation speed of the indoor fan is a step in which the control device switches the switching valve to perform control to reduce the rotation speed of the indoor fan when switching from a heat storage heating operation in which the indoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator to a defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator.

13. The control method for a refrigeration cycle device as described in claim 8, characterized in that the step in which the control device performs control to change the rotation speed of the indoor fan is a step in which the control device performs control to reduce the rotation speed of the indoor fan when switching from normal heating operation in which the indoor heat exchanger functions as a condenser and only the outdoor heat exchanger functions as an evaporator to defrost heating operation in which the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator by switching the switching valve.

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