Refrigeration cycle device and method for controlling the refrigeration cycle device

Abstract

To suppress deterioration of comfort to a user when performing defrosting operation of an outdoor heat exchanger, and avoid deterioration of a defrosting capacity.SOLUTION: Upon starting defrosting operation, when a control unit 7 determines that a temperature of a heat storage material acquired from a heat storage temperature sensor HS is equal to or lower than a first threshold value set in advance, the control unit 7 controls a plurality of switching valves 6 so that with a third pressure reduction mechanism 53 closed, an outdoor heat exchanger 3 functions as a condenser and an indoor heat exchanger 2 functions as an evaporator, to perform a reverse defrosting operation to defrost the outdoor heat exchanger 3; and when determining that the temperature of the heat storage material is higher than the first threshold value, the control unit 7 controls the plurality of switching valves 6 so that with a first pressure reduction mechanism 51 closed, the outdoor heat exchanger 3 functions as a condenser and a heat storage heat exchanger 4 functions as an evaporator, to perform an indoor heat exchange bypass defrosting operation to defrost the outdoor heat exchanger 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Generally, when an air conditioner is in heating operation, a low-temperature refrigerant flows through the outdoor heat exchanger. For this reason, when the outdoor air temperature is below freezing, for example, if the temperature of the refrigerant 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 a defrosting operation is necessary for operating an air conditioner, and typically, the defrosting operation is performed by interrupting the heating operation. Specifically, when starting the defrosting operation, the refrigerant circuit is switched so that the refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger, and the outdoor heat exchanger functions as a condenser to melt the frost and perform defrosting. In the defrosting operation, the high-temperature refrigerant supplied to the outdoor heat exchanger for defrosting becomes low temperature by melting the frost, and the low-temperature refrigerant flows into the indoor heat exchanger.

[0004] When such a defrosting operation is performed, as described above, the heating operation is stopped during the defrosting operation, so the indoor temperature gradually drops, reducing the comfort of the user. In addition, the passage of the refrigerant that has been cooled by the defrosting of the outdoor heat exchanger cools the piping and other parts of the indoor heat exchanger. Therefore, even if the heating operation is started again after the defrosting operation, low-temperature air will be blown into the room until the indoor heat exchanger warms up, which may reduce comfort.

[0005] Therefore, the following Patent Document 1 discloses an invention that prevents a drop in indoor temperature due to the temporary stop of heating operation by continuing heating operation even during defrosting operation, thereby maintaining comfort.

[0006] More specifically, in the invention disclosed in Patent Document 1, a heat storage device is placed in the refrigeration circuit separately from the indoor heat exchanger, and during defrosting operation, the total amount of heat stored in the heat storage device is used solely for defrosting, thereby shortening the defrosting time and limiting the drop in indoor temperature to a short period of time. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 06-074618 Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of the air conditioner shown in Patent Document 1 mentioned above, although it is true that the use of a heat storage device makes it possible to prevent low-temperature refrigerant from flowing into the indoor heat exchanger during defrosting operation, since the heat source used for defrosting is limited to the heat stored in the heat storage device, it is considered that the defrosting operation capacity will be reduced compared to conventional methods that use refrigerant discharged from the compressor.

[0009] Here, one of the heat sources of the refrigerant when defrosting the outdoor heat exchanger is the indoor air. That is, in the defrosting operation, the refrigerant, whose temperature has been reduced by defrosting the outdoor heat exchanger, flows into the indoor heat exchanger, and exchanges heat with the indoor air that has been warmed by the heating operation performed before the defrosting operation and the heat transfer tubes of the indoor heat exchanger, etc., so that the refrigerant absorbs heat and is used again to defrost the outdoor heat exchanger.

[0010] However, in the case of the defrosting method shown in Patent Document 1, the heat of the indoor heat exchanger is not used for the defrosting operation, so that the defrosting capacity is significantly reduced, especially when sufficient heat is not stored in the heat storage device, and the defrosting operation takes longer than before, reducing comfort.

[0011] The present invention aims to provide a refrigeration cycle device and a control method for a refrigeration cycle device that can suppress the decrease in user comfort when performing defrosting operation of such an outdoor heat exchanger and also avoid a decrease in defrosting capacity. [Means for solving the problem]

[0012] A refrigeration cycle device according to one aspect of the present invention includes a refrigerant circuit for circulating a refrigerant, 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, a plurality of pressure reducing mechanisms with adjustable opening degrees, a heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger function as an evaporator, and a defrosting operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger or the heat storage heat exchanger functions as an evaporator. a heat storage temperature sensor for measuring a temperature of a heat storage material, and a control unit for controlling the plurality of switching valves, the plurality of pressure reducing mechanisms including a first pressure reducing mechanism provided downstream of an indoor heat exchanger, a second pressure reducing mechanism provided upstream of a heat storage heat exchanger, and a third pressure reducing mechanism provided downstream of the heat storage heat exchanger in the refrigerant circulation path during heating operation, and when starting a defrosting operation, the temperature of the heat storage material acquired by the control unit from the heat storage temperature sensor is In order to determine whether the heat stored in the heat storage material of the heat storage heat exchanger can be used for the defrosting operation of the outdoor heat exchanger, When it is determined that the temperature is equal to or lower than a predetermined first threshold, the control unit closes the third pressure reduction mechanism and controls the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator to execute a reverse defrosting operation to defrost the outdoor heat exchanger, and when it is determined that the temperature of the heat storage material is higher than the first threshold, the control unit closes the first pressure reduction mechanism and controls the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator to execute an indoor heat exchanger bypass defrosting operation to defrost the outdoor heat exchanger.

[0013] A control method for a refrigeration cycle device according to an aspect of the present invention includes a refrigerant circuit for circulating a refrigerant, 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, a plurality of pressure reducing mechanisms with adjustable opening degrees, and a heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger function as an evaporator, and a defrosting operation in which the outdoor heat exchanger functions as a condenser, the indoor heat exchanger, or the heat storage heat exchanger functions as an evaporator. a heat storage temperature sensor for measuring a temperature of a heat storage material, and a control unit for controlling the plurality of switching valves, and the plurality of pressure reducing mechanisms include a first pressure reducing mechanism provided downstream of an indoor heat exchanger, a second pressure reducing mechanism provided upstream of a heat storage heat exchanger, and a third pressure reducing mechanism provided downstream of the heat storage heat exchanger in the refrigerant circulation path during heating operation, and the plurality of pressure reducing mechanisms are configured to detect, after a transition from heating operation to defrosting operation, the temperature of the heat storage material obtained by the control unit from the heat storage temperature sensor becomes In order to determine whether the heat stored in the heat storage material of the heat storage heat exchanger can be used for the defrosting operation of the outdoor heat exchanger, The method includes a step of determining whether the temperature of the heat storage material is equal to or lower than a predetermined first threshold; a step of, when it is determined that the temperature of the heat storage material is equal to or lower than the first threshold, the control unit closes the third pressure reduction mechanism and controls the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator to execute a reverse defrosting operation to defrost the outdoor heat exchanger; and a step of, when it is determined that the temperature of the heat storage material is higher than the first threshold, the control unit closes the first pressure reduction mechanism and controls the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator to execute an indoor heat exchanger bypass defrosting operation to defrost the outdoor heat exchanger. Effect of the Invention

[0014] According to the present invention, it is possible to suppress a decrease in user comfort when a defrosting operation of an outdoor heat exchanger is performed, and also to avoid a decrease in defrosting capacity. [Brief description of the drawings]

[0015] [Figure 1]1 is a refrigerant circuit diagram of a refrigeration cycle device according to an embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an internal configuration of a control unit in the refrigeration cycle apparatus according to the embodiment of the present invention. FIG. [Diagram 3] 2 is a refrigerant circuit diagram showing a flow of a refrigerant when the refrigeration cycle device according to the embodiment of the present invention performs a heating and heat storage operation. FIG. [Figure 4] FIG. 2 is a refrigerant circuit diagram showing a flow of refrigerant when the refrigeration cycle apparatus according to the embodiment of the present invention performs a reverse defrosting operation. [Diagram 5] FIG. 2 is a refrigerant circuit diagram showing a flow of refrigerant when the refrigeration cycle apparatus according to the embodiment of the present invention performs an indoor heat exchanger bypass defrosting operation. [Figure 6] 1 is a refrigerant circuit diagram showing a flow of a refrigerant when a refrigeration cycle device according to an embodiment of the present invention performs a heating and defrosting operation. [Figure 7] 4 is a flowchart showing a control flow when a defrosting operation is performed in the refrigeration cycle apparatus according to the embodiment of the present invention. [Figure 8] 4 is a flowchart showing a control flow when a defrosting operation is performed in the refrigeration cycle apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The structure of a refrigeration cycle apparatus S according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus S according to the embodiment of the present invention. The refrigeration cycle apparatus S includes a refrigerant circuit C in which a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4, a pressure reducing mechanism 5, and a switching valve 6 are connected, and which circulates the refrigerant. The refrigeration cycle apparatus S also includes a control unit 7 that controls the switching valve 6.

[0017] The compressor 1 compresses the refrigerant circulating inside the refrigerant circuit C. The indoor heat exchanger 2 exchanges heat between the indoor air and the refrigerant. The outdoor heat exchanger 3 exchanges heat between the outdoor air and the refrigerant. The structures of the compressor 1, the indoor heat exchanger 2, and the outdoor heat exchanger 3 will not be described here, but devices with various structures can be adopted.

[0018] The heat storage heat exchanger 4 is a heat exchanger in which heat is exchanged between the heat storage material filled inside and the refrigerant passing through the heat storage heat exchanger 4. Heat supplied from the refrigerant is stored in this heat storage material, and the stored heat is used for heating operation or defrosting operation as described later. In addition, a heat storage temperature sensor HS, which will be described later, is provided at a position where the temperature of the heat storage material can be measured.

[0019] The pressure reduction mechanism 5 is formed so that the opening degree can be adjusted, and a plurality of pressure reduction mechanisms are provided in the refrigeration cycle apparatus S in the embodiment of the present invention. Specifically, three pressure reduction mechanisms are provided, and a first pressure reduction mechanism 51 is provided between the indoor heat exchanger 2 and the outdoor heat exchanger 3. A second pressure reduction mechanism 52 is provided between the compressor 1 and the heat storage heat exchanger 4 or the outdoor heat exchanger 3. A third pressure reduction mechanism 53 is provided between the heat storage heat exchanger 4 and the outdoor heat exchanger 3.

[0020] The switching valve 6 switches the circulation path of the refrigerant in the refrigerant circuit C between 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, and defrosting operation, in which the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 2 or the heat storage heat exchanger 4 functions as an evaporator.

[0021] In addition, in the refrigeration cycle apparatus S in the embodiment of the present invention, a plurality of switching valves 6 are also provided. That is, a first switching valve 61 is provided between the compressor 1 and the indoor heat exchanger 2. A second switching valve 62 is provided between the compressor 1 and the heat storage heat exchanger 4. And a third switching valve 63 is provided between the compressor 1 and the outdoor heat exchanger 3.

[0022] In the following, when these three pressure reducing mechanisms are described collectively, they will be referred to as "pressure reducing mechanism 5" as appropriate, and when each pressure reducing mechanism is described individually, they will be referred to by their respective names. Similarly, when these three switching valves are described collectively, they will be referred to as "switching valve 6" as appropriate, and when each switching valve is described individually, they will be referred to by their respective names.

[0023] The control unit 7 controls the opening degree of the multiple pressure reduction mechanisms 5. The control unit 7 controls the opening degree of each pressure reduction mechanism, thereby adjusting the flow rate of the refrigerant flowing through the refrigerant circuit C. As described above, the control unit 7 switches the flow of the refrigerant circulating through the refrigerant circuit C by switching the multiple switching valves 6.

[0024] In this way, the control unit 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 pressure reducing mechanisms 5 and the multiple switching valves 6. The control unit 7 also controls the defrosting operation of the outdoor heat exchanger 3.

[0025] Next, the control contents by the control unit 7 will be described in more detail. Fig. 2 is a block diagram showing the internal configuration of the control unit 7 in the refrigeration cycle apparatus S according to the embodiment of the present invention. The control unit 7 includes a temperature detection unit 71, a storage unit 72, a determination unit 73, and a defrosting operation control unit 74.

[0026] The temperature detection unit 71 acquires the temperature of the heat storage material detected by the heat storage temperature sensor HS provided in the heat storage heat exchanger 4. The temperature of the heat storage material detected by the heat storage temperature sensor HS may be transmitted from the heat storage temperature sensor HS to the temperature detection unit 71 at predetermined time intervals. Alternatively, conversely, the temperature detection unit 71 may obtain the temperature from the heat storage temperature sensor HS as necessary.

[0027] The storage unit 72 stores information for comparison with the temperature of the heat storage material acquired by the temperature detection unit 71. That is, a first threshold value and a second threshold value are set in advance and stored in the storage unit 72. Both of the first threshold value and the second threshold value are used when the determination unit 73 determines the mode of the defrosting operation executed by the defrosting operation control unit 74 described later.

[0028] The relationship between the first threshold value and the second threshold value can be set in any manner, but in the embodiment of the present invention, it is assumed that the second threshold value is set to a value higher than the first threshold value.

[0029] Here, the "first threshold" is a reference value used to determine whether or not to perform a reverse defrosting operation, which will be described later. Specifically, it is a value that indicates a state in which the amount of heat stored in the heat storage material of the heat storage heat exchanger 4 is so small that the defrosting operation may be prolonged. On the other hand, the "second threshold" is a reference value used to determine whether or not to perform a heating defrosting operation, which will be described later. Specifically, it is a value that indicates a state in which the amount of heat stored in the heat storage material is so large that not only the defrosting operation but also the heating operation can be performed in parallel. As described above, this is why the second threshold is set to a value higher than the first threshold.

[0030] The judgment unit 73 uses the temperature of the heat storage material acquired by the temperature detection unit 71 from the heat storage temperature sensor HS and the first threshold value or the second threshold value stored in the memory unit 72 to judge which operating mode to select as the defrosting operation for the outdoor heat exchanger 3.

[0031] In the embodiment of the present invention, three modes of defrosting operation are set, for example, a reverse defrosting operation, an indoor heat exchanger bypass defrosting operation, and a heating defrosting operation, which will be described later. The determination unit 73 compares the temperature of the heat storage material with a first threshold value or a second threshold value to select one of the operation modes.

[0032] Information regarding the operation mode selected by the determination unit 73 is transmitted to the defrosting operation control unit 74, and the defrosting operation control unit 74 controls the pressure reducing mechanism 5 and the switching valve 6 in accordance with the operation mode received from the determination unit 73.

[0033] Next, the various defrosting operations mentioned above will be explained in order using the circuit diagram of the refrigeration cycle apparatus S in the embodiment of the present invention. Before that, the heating operation in the basic refrigeration cycle apparatus S will be explained using Fig. 3. Fig. 3 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle apparatus S in the embodiment of the present invention performs a heating heat storage operation. Here, the heating heat storage operation is an operation in which the indoor heat exchanger 2 is used as a condenser while heat is stored by dissipating heat from the refrigerant to the heat storage material in the heat storage heat exchanger 4.

[0034] In the circuit diagrams used in the following description, including Fig. 3, the refrigerant circuit C through which the refrigerant actually flows is shown by a solid line. On the other hand, the refrigerant circuits C that constitute the refrigerant circuit C but through which the refrigerant does not flow are shown by a dashed line. The direction of the refrigerant flowing in the refrigerant circuit C is also shown by an arrow.

[0035] When the refrigeration cycle apparatus S performs heating and heat storage operation, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61. Then, in the indoor heat exchanger 2, heat is exchanged between the refrigerant and the air flowing into the indoor unit, and air that has absorbed heat from the refrigerant and been warmed is supplied to the indoor space. Therefore, the indoor heat exchanger 2 functions as a condenser.

[0036] The refrigerant flowing out of the indoor heat exchanger 2 flows into the outdoor heat exchanger 3 via the first pressure reducing mechanism 51. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the compressor 1 via the third switching valve 63.

[0037] The refrigeration cycle apparatus S in the embodiment of the present invention is provided with a heat storage heat exchanger 4 in addition to the indoor heat exchanger 2 and the outdoor heat exchanger 3. When the heating heat storage operation is performed, the refrigerant discharged from the compressor 1 not only flows into the indoor heat exchanger 2 as described above, but also flows into the heat storage heat exchanger 4 via the second pressure reducing mechanism 52 and the second switching valve 62.

[0038] In the heat storage heat exchanger 4, the refrigerant exchanges heat with the heat storage material, so that the heat of the refrigerant is stored in the heat storage material. The temperature of the heat storage material due to the heat storage is detected by the heat storage temperature sensor HS, and is appropriately transmitted to the temperature detection unit 71 of the control unit 7 as described above.

[0039] The refrigerant that flows out of the heat storage heat exchanger 4 after heat exchange in the heat storage heat exchanger 4 flows into the outdoor heat exchanger 3 via the third pressure reduction mechanism 53, and then flows out of the outdoor heat exchanger 3 and into the compressor 1 via the third switching valve 63.

[0040] The control unit 7 executes control of the heating and heat storage operation in the refrigeration cycle apparatus S, and also executes control of an operation for defrosting the outdoor heat exchanger 3. As described above, there are several modes for controlling the defrosting operation, and first, the reverse defrosting operation will be described.

[0041] 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 a reverse defrosting operation. The reverse defrosting operation is an operation mode in which the refrigeration cycle apparatus S performing the heating and heat storage operation is switched from the heating operation to the cooling operation state to defrost the outdoor heat exchanger 3.

[0042] Specifically, when starting the defrosting operation, if the determination unit 73 determines that the temperature of the heat storage material is equal to or lower than the first threshold value, first, the defrosting operation control unit 74 closes the third pressure reduction mechanism 53.

[0043] When determining whether or not to perform the reverse defrosting operation, the determination unit 73 uses a first threshold value. This first threshold value is used to determine whether or not the heat stored in the heat storage material of the heat storage heat exchanger 4 can be used for the defrosting operation of the outdoor heat exchanger 3.

[0044] As a result, if the temperature of the heat storage material transmitted from the heat storage temperature sensor HS is below the first threshold value, the judgment unit 73 judges that the amount of heat stored in the heat storage material of the heat storage heat exchanger 4 is small and cannot be used for the defrosting operation of the outdoor heat exchanger 3.

[0045] Therefore, in such a case, the defrosting operation control unit 74 first controls the third pressure reduction mechanism 53 to the closed state as described above. By controlling the third pressure reduction mechanism 53 in this manner, the refrigerant discharged from the compressor 1 does not flow into the heat-storage heat exchanger 4.

[0046] Therefore, the defrosting operation control unit 74 performs reverse defrosting operation to defrost the outdoor heat exchanger 3 by controlling the multiple switching valves 6 so that the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 2 functions as an evaporator.

[0047] Specifically, the defrosting operation control unit 74 controls both the first pressure reduction mechanism 51 and the second pressure reduction mechanism 52 to an open state. Also, the first switching valve 61 and the third switching valve 63 are switched so that the discharge side of the compressor is connected to the outdoor heat exchanger 3 and the suction side of the compressor is connected to the indoor heat exchanger 2.

[0048] In this manner, the defrosting operation control unit 74 controls the multiple pressure reduction mechanisms 5 and the multiple switching valves 6, so that the high-temperature refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 via the second pressure reduction mechanism 52 and the third switching valve 63, as shown by the arrows in Figure 4.

[0049] The heat of the refrigerant that flows in melts the frost that has adhered to the outdoor heat exchanger 3. The refrigerant, whose temperature has been reduced by melting the frost, flows out of the outdoor heat exchanger 3 and flows into the indoor heat exchanger 2 via the first pressure reduction mechanism 51. Note that, since the third pressure reduction mechanism 53 is controlled to a closed state as described above, the refrigerant that flows out of the outdoor heat exchanger 3 does not flow into the heat storage heat exchanger 4.

[0050] The refrigerant that has flowed into the indoor heat exchanger 2 exchanges heat with the air flowing into the indoor unit, evaporates, flows out of the indoor heat exchanger 2, and then flows into the compressor 1 via the first switching valve 61. When the heat stored in the heat storage material of the heat storage heat exchanger 4 cannot be utilized in this manner, the defrosting operation of the outdoor heat exchanger 3 is performed using only the heat of the refrigerant discharged from the compressor 1 without utilizing the heat stored in the heat storage material.

[0051] Next, the control of the indoor heat exchanger bypass defrosting operation will be described with reference to Fig. 5. Fig. 5 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 indoor heat exchanger bypass defrosting operation.

[0052] Here, the “indoor heat exchange bypass defrosting operation” is a defrosting operation that differs from the above-mentioned reverse defrosting operation in that the refrigerant used in the defrosting operation of the outdoor heat exchanger 3 is not allowed to flow into the indoor heat exchanger 2, but is allowed to flow into the heat storage heat exchanger 4.

[0053] That is, in the case of reverse defrost operation, the heat stored in the heat storage material of the heat storage heat exchanger 4 cannot be used for the defrost operation. Therefore, the refrigerant used in the defrost operation of the outdoor heat exchanger 3 is sent to the compressor 1 via the indoor heat exchanger 2 without passing through the heat storage heat exchanger 4.

[0054] However, because the defrosting operation for the outdoor heat exchanger 3 lowers the temperature of the refrigerant, the temperature of the refrigerant flowing into the indoor heat exchanger 2 remains low. Therefore, the pipes and other parts of the indoor heat exchanger 2, which had been warmed by the heating and heat storage operation, are cooled by the low-temperature refrigerant and become cold.

[0055] Therefore, even if the heating and heat storage operation is started again after the defrosting operation of the outdoor heat exchanger 3 is completed, the various parts of the indoor heat exchanger 2 are still cold and will not warm up immediately. Until the room warms up, for example, low-temperature air will be supplied to the room, which may result in a decrease in comfort for the user.

[0056] Therefore, an indoor heat exchange bypass defrosting operation is performed as a control that prevents the temperature of the indoor heat exchanger 2 from decreasing, and that enables warm air to be immediately supplied to the room without reducing the comfort of the user when the defrosting operation is terminated and the heating and heat storage operation is started again.

[0057] Specifically, when the determination unit 73 determines that the temperature of the heat storage material is higher than the first threshold value and equal to or lower than the second threshold value, the control of the indoor heat exchanger bypass defrosting operation is executed. When the determination unit 73 makes such a determination, the defrosting operation control unit 74 first controls the first pressure reduction mechanism 51 to be in a closed state.

[0058] In other words, by closing the first pressure reduction mechanism 51, it is possible to prevent the indoor heat exchanger 2 from being cooled by the refrigerant used in the defrosting operation of the outdoor heat exchanger 3 flowing into the indoor heat exchanger 2 during defrosting operation, as shown in Figure 5.

[0059] Furthermore, by controlling the first pressure reduction mechanism 51 to a closed state by the defrosting operation control unit 74, the low-temperature refrigerant used in the defrosting operation of the outdoor heat exchanger 3 flows into the heat storage heat exchanger 4 via the third pressure reduction mechanism 53. As described above, the determination unit 73 determines that the temperature of the heat storage material is higher than the first threshold value, so that the heat stored in the heat storage heat exchanger 4 can be used for the defrosting operation of the outdoor heat exchanger 3.

[0060] Therefore, the defrosting operation control unit 74 controls the second switching valve 62 to switch so that the outdoor heat exchanger 3 functions as a condenser and the heat storage heat exchanger 4 functions as an evaporator. By performing such control by the control unit 7, the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 via the second pressure reducing mechanism 52 and the third switching valve 63, and the defrosting operation is performed.

[0061] Then, since the first pressure reduction mechanism 51 is controlled to a closed state and the third pressure reduction mechanism 53 is controlled to an open state, the refrigerant used for the defrosting operation of the outdoor heat exchanger 3 flows into the heat storage heat exchanger 4 via the third pressure reduction mechanism 53. In the heat storage heat exchanger 4, the heat stored in the heat storage material is absorbed by the flowing-in refrigerant, and in this state, the refrigerant flows out of the heat storage heat exchanger 4. The refrigerant that flows out of the heat storage heat exchanger 4 returns to the compressor 1 via the second switching valve 62.

[0062] Therefore, the refrigerant that has been cooled by the defrosting operation of the outdoor heat exchanger 3 does not flow into the indoor heat exchanger 2, so that the temperatures of the various parts of the indoor heat exchanger 2 that have been warmed by the heating and heat storage operation performed before the defrosting operation do not decrease and can be maintained in a warm state. Therefore, even immediately after switching from the defrosting operation to the heating and heat storage operation, warm air can be supplied to the room, so that a decrease in comfort for the user can be avoided.

[0063] In addition, after the defrosting operation has been performed, the refrigerant flows into the heat storage heat exchanger 4 and exchanges heat with the heat storage material, so that the heat stored in the heat storage material can be used for the defrosting operation of the outdoor heat exchanger 3.

[0064] Furthermore, when the determination unit 73 determines that the temperature of the heat storage material is higher than the second threshold value, a defrosting operation is performed on the outdoor heat exchanger 3 as follows. Fig. 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 performs a heating defrosting operation.

[0065] When the determination unit 73 determines that the temperature of the heat storage material acquired from the heat storage temperature sensor HS is higher than the second threshold value, it indicates that sufficient heat is stored in the heat storage heat exchanger 4 so that it can be used for heating operation in addition to the defrosting operation of the outdoor heat exchanger 3. Therefore, when the temperature of the heat storage material is higher than the second threshold value, the defrosting operation control unit 74 executes a heating / defrosting operation in which a heating operation and a defrosting operation are executed simultaneously.

[0066] Specifically, as is clear from the refrigerant circuit diagram shown in FIG. 6, the judgment unit 73 controls the multiple switching valves 6 so that 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.

[0067] That is, to perform the heating operation, the first switching valve 61 is controlled so that the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2. Since the defrosting operation is performed simultaneously with the heating operation, the third switching valve 63 is switched so that the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3. Then, the second switching valve 62 is switched so that the refrigerant flows from the heat storage heat exchanger 4 to the compressor 1.

[0068] Meanwhile, the defrosting operation control unit 74 controls all of the first pressure reduction mechanism 51 to the third pressure reduction mechanism 53 to be in an open state. Therefore, the refrigerant that has exchanged heat with the indoor air in the indoor heat exchanger 2 and the refrigerant used in the defrosting operation for the outdoor heat exchanger 3 flow into the heat storage heat exchanger 4 via the third pressure reduction mechanism 53. Then, the refrigerant that flows out of the heat storage heat exchanger 4 returns to the compressor 1 via the second switching valve 62.

[0069] On the premise that a sufficiently high-temperature refrigerant is stored in the heat storage heat exchanger 4, the pressure reducing mechanism 5 and the switching valve 6 are controlled in this manner, so that the heat stored in the heat storage heat exchanger 4 can be used for the defrosting operation of the outdoor heat exchanger 3. Therefore, the heating operation can be performed simultaneously with the defrosting operation.

[0070] In each operation mode such as the reverse defrosting operation described above, it is assumed that the heating operation is being performed. On the other hand, when the heating operation is not being performed, the refrigeration cycle apparatus S only needs to focus on the defrosting operation. Therefore, the defrosting operation performed while the heating operation is stopped will be described below.

[0071] When the control unit 7 receives a signal to stop the heating operation, it determines whether or not to perform a defrosting operation. For example, when the temperature of the outdoor heat exchanger 3 is below 0°C and the heating operation has been performed for 30 minutes or more, it is expected that frost has formed on the outdoor heat exchanger 3. Therefore, the control unit 7 determines that a defrosting operation is necessary in such a case.

[0072] The conditions under which the control unit 7 determines that a defrosting operation is necessary are not limited to the above conditions, and various conditions can be set. The heating operation stop signal here includes a stop signal due to thermo-off, in addition to a case where the user instructs the heating operation to be stopped using the remote control.

[0073] When it is determined that a defrosting operation is necessary as a result of the determination in the control unit 7 as to whether or not a defrosting operation is necessary, the temperature of the heat storage material detected by the heat storage temperature sensor HS is acquired via the temperature detection unit 71. Then, it is determined whether the acquired temperature of the heat storage material is equal to or lower than a first threshold value. If the temperature of the heat storage material is equal to or lower than the first threshold value, the above-mentioned reverse defrosting operation is executed.

[0074] On the other hand, when the temperature of the heat storage material indicates a value greater than the first threshold value, the indoor heat exchanger bypass defrosting operation is executed. Then, when a separately determined termination condition for the defrosting operation is satisfied, the reverse defrosting operation or the indoor heat exchanger bypass defrosting operation is terminated.

[0075] It should be noted that since the defrosting operation described here is premised on being performed while the heating operation is stopped, as described above, the determination unit 73 does not compare the temperature of the heat storage material with the second threshold value.

[0076] The above describes the defrosting operation during heating operation or when heating operation is stopped. Various conditions can be set for terminating the defrosting operation, but an example is as follows. For example, in the case of reverse defrosting operation, the defrosting operation ends when a predetermined time (which can be set arbitrarily, for example, 10 minutes) has elapsed since the start of reverse defrosting operation, or when the temperature of the outdoor heat exchanger 3 (which can be set arbitrarily, for example, 10°C) has become equal to or higher.

[0077] [Operation] Next, the flow of control of the refrigeration cycle apparatus S by the control unit 7 in the above-mentioned reverse defrosting operation, indoor heat exchanger bypass defrosting operation, and heating defrosting operation will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the flow of control when performing the defrosting operation in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0078] First, the control unit 7 determines whether the refrigeration cycle apparatus S is in heating operation (heating heat storage operation) (ST1). That is, the control unit 7 checks whether the above-mentioned heating operation stop signal has been received.

[0079] As a result, when it is determined that the heating heat storage operation is being performed (YES in ST1), the control unit 7 then determines whether or not a defrosting operation is required for the outdoor heat exchanger 3 (ST2). Note that the flow of processing when it is determined by the control unit 7 that the heating operation is not being performed (NO in ST1) will be described later.

[0080] The conditions under which the control unit 7 determines whether or not a defrosting operation is required during a heating operation may be, for example, that the temperature of the outdoor heat exchanger 3 is -5°C or lower and the heating operation has been performed for 60 minutes or more. Alternatively, in addition to the conditions of the temperature of the outdoor heat exchanger 3 and the operation time of the heating operation, a condition related to the outdoor air temperature may be added. In this way, the conditions can be set in various ways.

[0081] Note that the conditions for determining whether a defrosting operation is necessary during the heating operation are different from the conditions for determining whether a defrosting operation is necessary while the heating operation is stopped. That is, during the heating operation, from the viewpoint of ensuring the comfort of the user during the operation, the defrosting operation is started if there is frost that requires immediate defrosting. On the other hand, when the heating operation is stopped, there is no restriction from such a viewpoint, so that, for example, when the heating operation is started again, if there is even a small amount of frost, the defrosting operation is started so that the operation can be performed in a frost-free state. Therefore, the conditions for determining whether a defrosting operation is necessary are stricter during the heating operation than when the heating operation is stopped.

[0082] When the control unit 7 determines that a defrosting operation is not necessary for the outdoor heat exchanger 3 (NO in ST2), the heating heat storage operation is continued. On the other hand, when the control unit 7 determines that a defrosting operation is necessary (YES in ST2), the defrosting operation for the outdoor heat exchanger 3 is started (ST3).

[0083] In the control unit 7, in order to determine the mode of the defrosting operation, the temperature detection unit 71 acquires the temperature of the heat storage material from the heat storage temperature sensor HS and transmits it to the determination unit 73. In addition, the determination unit 73 accesses the storage unit 72 to acquire the first threshold value and the second threshold value stored in the storage unit 72 in advance.

[0084] Then, the judgment unit 73 judges, based on the temperature of the heat storage material obtained from the temperature detection unit 71 and the first and second threshold values ​​obtained from the memory unit 72, what relationship the temperature of the heat storage material has with these threshold values.

[0085] First, it is determined whether the temperature of the heat storage material is equal to or lower than the first threshold value (ST4). If it is determined that the temperature of the heat storage material is equal to or lower than the first threshold value (YES in ST4), it instructs the defrosting operation control unit 74 to execute a reverse defrosting operation.

[0086] The defrosting operation control unit 74 closes the third pressure reduction mechanism based on the judgment result of the judgment unit 73, and controls the multiple switching valves 6 so that the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 2 functions as an evaporator, thereby performing a reverse defrosting operation to defrost the outdoor heat exchanger 3 (ST5).

[0087] On the other hand, if the determining unit 73 determines that the temperature of the heat storage material is greater than the first threshold value (NO in ST4), the temperature of the heat storage material is further compared with a second threshold value (ST6).

[0088] As a result, when the determination unit 73 determines that the temperature of the heat storage material is equal to or lower than the second threshold value (YES in ST6), it instructs the defrosting operation control unit 74 to execute the indoor heat exchanger bypass defrosting operation.

[0089] Based on the judgment result of the judgment unit 73, the defrosting operation control unit 74 closes the first pressure reduction mechanism 51 and controls the multiple switching valves 6 so that the outdoor heat exchanger 3 functions as a condenser and the heat storage heat exchanger 4 functions as an evaporator, thereby performing an indoor heat exchange bypass defrosting operation to defrost the outdoor heat exchanger 3 (ST7).

[0090] On the other hand, when the determination unit 73 determines that the temperature of the heat storage material is greater than the second threshold value (NO in ST6), a heating and defrosting operation is executed simultaneously (ST8).

[0091] In this way, by comparing the temperature of the heat storage material with the first threshold value or the second threshold value, any one of the above-mentioned reverse defrosting operation, indoor heat exchanger bypass defrosting operation, and heating defrosting operation is selected and executed.

[0092] While any of these defrosting operations is being performed, the control unit 7 determines whether or not the frost on the outdoor heat exchanger 3 has melted and it is OK to end the defrosting operation, based on the end condition described above (ST9).

[0093] If the control unit 7 determines that the frost on the outdoor heat exchanger 3 has not melted sufficiently and the defrosting operation cannot be terminated yet (NO in ST9), the defrosting operation that is being executed continues (ST10). On the other hand, if the control unit 7 determines that the defrosting operation can be terminated (YES in ST9), the defrosting operation is terminated (ST11).

[0094] Although not shown in the flowchart of FIG. 7, the heating and heat storage operation may be started again after the defrosting operation is completed.

[0095] Next, when the heating operation is not in progress (NO in ST1), that is, when the heating operation is stopped, the process of the defrosting operation will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the flow of control when the defrosting operation is performed in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0096] After the control unit 7 receives a signal to stop the heating operation and determines that the heating operation is not in progress, the determination unit 73 first determines whether or not a defrosting operation is necessary (ST21). The conditions for determining whether or not a defrosting operation is necessary are as described above.

[0097] When it is determined that a defrosting operation is necessary (YES in ST21), the defrosting operation is started (ST22). At that time, in the control unit 7, in order to determine the mode of the defrosting operation, the temperature detection unit 71 acquires the temperature of the heat storage material from the heat storage temperature sensor HS and transmits it to the judgment unit 73. In addition, the judgment unit 73 accesses the storage unit 72 to acquire a first threshold value stored in the storage unit 72 in advance.

[0098] The determination unit 73 determines whether the temperature of the heat storage material is equal to or lower than the first threshold value (ST23). If it is determined that the temperature of the heat storage material is equal to or lower than the first threshold value (YES in ST23), the determination unit 73 instructs the defrosting operation control unit 74 to execute a reverse defrosting operation.

[0099] On the other hand, when the determination unit 73 determines that the temperature of the heat storage material is higher than the first threshold value (NO in ST23), it instructs the defrosting operation control unit 74 to perform an indoor heat exchanger bypass defrosting operation.

[0100] After these defrosting operations are performed, in either case, a determination is made as to whether or not to terminate the defrosting operation as appropriate, as shown in step ST9 of Fig. 7. The flow of control based on the result of this determination is as described above.

[0101] If it is determined that the defrosting operation is not necessary while the heating operation is stopped (NO in ST21), the defrosting operation is not executed and the process ends.

[0102] As described above, by performing a defrosting operation suited to the current situation based on the temperature of the heat storage material in the heat storage heat exchanger 4 from among a plurality of defrosting operation modes, it is possible to provide a refrigeration cycle apparatus and a control method for a refrigeration cycle apparatus that can suppress a decrease in user comfort when performing a defrosting operation of the outdoor heat exchanger and also avoid a decrease in defrosting capacity.

[0103] 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 without departing from the gist of the invention, and various modifications and improvements can be made to the above-described embodiment. In addition, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiment.

[0104] For example, some of the components shown in the embodiment may be deleted. Furthermore, components from different embodiments may be appropriately combined, and such modified or improved forms may also be included in the present invention. Such embodiments and modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0105] REFERENCE SIGNS LIST 1 compressor, 2 indoor heat exchanger, 3 outdoor heat exchanger, 4 heat storage heat exchanger, 5 pressure reduction mechanism, 51 first pressure reduction mechanism, 52 second pressure reduction mechanism, 53 third pressure reduction mechanism, 6 changeover valve, 61 first changeover valve, 62 second changeover valve, 63 third changeover valve, 7 control unit, 71 temperature detection unit, 72 memory unit, 73 determination unit, 74 defrosting operation control unit, C refrigerant circuit, HS heat storage temperature sensor, S refrigeration cycle device

Claims

1. The 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 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 plurality of pressure reducing mechanisms whose opening degrees are adjustable; a plurality of switching valves that switch a circulation path of the refrigerant in the refrigerant circuit between a heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger function as an evaporator, and a defrosting operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger or the heat storage heat exchanger functions as an evaporator; A heat storage temperature sensor for measuring the temperature of the heat storage material; A control unit that controls the plurality of switching valves, the plurality of pressure reduction mechanisms include a first pressure reduction mechanism provided downstream of the indoor heat exchanger, a second pressure reduction mechanism provided upstream of the heat storage heat exchanger, and a third pressure reduction mechanism provided downstream of the heat storage heat exchanger in a circulation path of the refrigerant during the heating operation; When starting the defrosting operation, if the control unit determines that the temperature of the heat storage material acquired from the heat storage temperature sensor is equal to or lower than a first threshold value that is set in advance for determining whether or not the heat stored in the heat storage material of the heat storage heat exchanger can be used for the defrosting operation of the outdoor heat exchanger, the control unit performs control to execute a reverse defrosting operation in which the third pressure reduction mechanism is placed in a closed state, and the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator by controlling the multiple switching valves, When it is determined that the temperature of the heat storage material is higher than the first threshold value, the control unit performs control to close the first pressure reduction mechanism and control the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator, thereby performing an indoor heat exchange bypass defrosting operation to defrost the outdoor heat exchanger.

2. 2. The refrigeration cycle device according to claim 1, wherein, when the control unit determines that the temperature of the heat storage material is higher than a second threshold value that is set higher than the first threshold value, the control unit controls the multiple switching valves so that the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator, and performs a heating / defrosting operation in which the heating operation and the defrosting operation are performed simultaneously.

3. When the control unit determines that the temperature of the heat storage material is equal to or lower than the first threshold value during the heating operation stop, the control unit performs control to execute the reverse defrosting, 2. The refrigeration cycle apparatus according to claim 1, wherein when it is determined that the temperature of the heat storage material is higher than the first threshold value, the control unit performs control to execute the indoor heat exchanger bypass defrosting operation.

4. The 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 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 plurality of pressure reducing mechanisms whose opening degrees are adjustable; a plurality of switching valves that switch a circulation path of the refrigerant in the refrigerant circuit between a heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger function as an evaporator, and a defrosting operation in which the outdoor heat exchanger functions as a condenser and the indoor heat exchanger or the heat storage heat exchanger functions as an evaporator; A heat storage temperature sensor for measuring the temperature of the heat storage material; A control unit that controls the plurality of switching valves, In the refrigeration cycle apparatus, the plurality of pressure reduction mechanisms include a first pressure reduction mechanism provided downstream of the indoor heat exchanger, a second pressure reduction mechanism provided upstream of the heat storage heat exchanger, and a third pressure reduction mechanism provided downstream of the heat storage heat exchanger in a circulation path of the refrigerant during the heating operation, After transitioning from the heating operation to the defrosting operation, A step of determining whether or not the temperature of the heat storage material acquired by the control unit from the heat storage temperature sensor is equal to or lower than a first threshold value that is set in advance to determine whether or not the heat stored in the heat storage material of the heat storage heat exchanger can be used for the defrosting operation of the outdoor heat exchanger; When it is determined that the temperature of the heat storage material is equal to or lower than the first threshold value, the control unit performs control to close the third pressure reduction mechanism, and to control the plurality of switching valves so that the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, thereby executing a reverse defrosting operation to defrost the outdoor heat exchanger; When it is determined that the temperature of the heat storage material is higher than the first threshold value, the control unit performs control to close the first pressure reduction mechanism, and to control the multiple switching valves so that the outdoor heat exchanger functions as a condenser and the heat storage heat exchanger functions as an evaporator, thereby executing an indoor heat exchange bypass defrosting operation to defrost the outdoor heat exchanger; A control method for a refrigeration cycle device comprising:

5. 5. The control method for a refrigeration cycle device according to claim 4, further comprising the step of: when the control unit determines that the temperature of the heat storage material is higher than a second threshold value that is set higher than the first threshold value, the control unit controls the plurality of switching valves so that the indoor heat exchanger and the outdoor heat exchanger function as condensers and the heat storage heat exchanger functions as an evaporator, and performing a heating / defrosting operation in which the heating operation and the defrosting operation are performed simultaneously.

6. The control unit further includes a step of determining whether or not the refrigeration cycle device is in a heating operation, and when the control unit determines that the refrigeration cycle device is in a heating operation stop, When the control unit determines that the temperature of the heat storage material is equal to or lower than the first threshold value, the control unit performs control to execute the reverse defrosting operation, 5. The control method for a refrigeration cycle apparatus according to claim 4, further comprising a step of: when the control unit determines that the temperature of the heat storage material is higher than the first threshold value, the control unit performs control to execute the indoor heat exchanger bypass defrosting operation.

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