Refrigeration cycle device and method for controlling the refrigeration cycle device

Abstract

To store heat required for defrosting while suppressing a decrease in comfort for a user when performing a defrosting operation, and to avoid an increase in cost when achieving both of these. [Solution] A refrigerant circuit C for circulating a refrigerant is connected to a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a heat storage heat exchanger 4 for exchanging heat between a heat storage material and the refrigerant, multiple expansion valves 5 whose opening degree can be adjusted, and multiple switching valves 6 that switch the refrigerant circulation path in the refrigerant circuit between heat storage heating operation and defrosting operation, and is equipped with a heat storage temperature sensor HS that detects the temperature of the heat storage material, and a control unit 7 that controls the multiple expansion valves 5, one of the multiple expansion valves 5 is a first expansion valve 51 provided upstream of the heat storage heat exchanger that functions as a condenser, and the control unit 7 controls the opening degree of the first expansion valve so that a second slope indicating the amount of rise per unit time of the temperature of the heat storage material stored during heat storage heating operation matches a predetermined first slope.

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, for example, when the outdoor air temperature is below freezing, 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 (for example, Patent Document 1).

[0003] Such a defrosting operation is necessary for the operation of 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, the heating operation is stopped and the indoor temperature gradually drops during the defrosting operation, which reduces the comfort of the user. Therefore, for example, a method can be considered in which a heat storage device is provided in the refrigeration circuit separately from the indoor heat exchanger, and the heat stored in the heat storage device is used for defrosting during the defrosting operation, thereby allowing the heating operation to continue even during the defrosting operation. This method can prevent the indoor temperature from dropping due to the heating operation being temporarily stopped for the defrosting operation, and maintain the comfort of the user.

[0005] When a heat storage device is provided in the refrigeration circuit, heat is stored in the heat storage device by causing a portion of the refrigerant flowing through the indoor heat exchanger during heating operation to flow into the heat storage device. In this case, if the amount of refrigerant flowing into the heat storage device becomes excessively large, the capacity of the indoor heat exchanger will be significantly reduced, which may result in a loss of comfort.

[0006] Therefore, in an air conditioner previously filed by the applicant of the present application (Patent Application No. 2022-120754), the above-mentioned inconveniences are avoided by controlling the opening degree of an expansion valve located on the path in the refrigeration circuit that flows refrigerant to the heat storage device so that the difference between the temperature of the heat storage material and the condensation temperature of the refrigerant flowing to the heat storage device is a predetermined temperature difference. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-322264 Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of the above-mentioned air conditioner, the condensation temperature of the refrigerant flowing in the heat storage device is used, so it is necessary to detect the condensation temperature. However, when the heat storage device is configured to immerse the heat storage heat exchanger in a liquid heat storage material, for example, it is difficult to detect the above-mentioned condensation temperature.

[0009] In other words, even if a temperature sensor is installed near the heat storage heat exchanger to detect the condensation temperature of the refrigerant flowing through the heat storage heat exchanger, since the heat storage heat exchanger is immersed in the heat storage material, it is possible that the detected temperature will be the temperature of the heat storage material rather than the condensation temperature of the refrigerant.

[0010] On the other hand, in order to ensure reliable detection of the condensation temperature, it is possible to consider, for example, installing a pressure sensor in the high-pressure side circuit and detecting the condensation temperature from the condensation pressure. However, pressure sensors are generally more expensive than temperature sensors, and detecting the condensation temperature using a pressure sensor could result in an increase in the cost of the entire air conditioner.

[0011] 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 store the heat required for defrosting while suppressing a decrease in user comfort when performing defrosting operation, and can avoid increased costs when achieving both of these. [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 expansion valves whose opening degrees are adjustable, the indoor heat exchanger, and a heat storage heating operation in which the heat storage heat exchanger functions as a condenser and the outdoor heat exchanger functions as an evaporator, and a heat storage heating operation in which the outdoor heat exchanger functions as an evaporator. , and indoor heat exchanger The condenser , storage a heat storage temperature sensor that detects the temperature of the heat storage material; and a control unit that controls the plurality of expansion valves, one of which is a first expansion valve provided upstream of the heat storage heat exchanger that functions as a condenser. The control unit calculates a second slope that indicates the amount of rise per unit time of the temperature of the heat storage material stored in the heat storage heating operation, such that Considering the condensation temperature of the indoor heat exchanger The opening degree of the first expansion valve is controlled so as to coincide with a preset first gradient.

[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 expansion valves with adjustable opening degrees, the indoor heat exchanger, and a heat-storage heating operation in which the heat-storage heat exchanger functions as a condenser and the outdoor heat exchanger functions as an evaporator, and a heat-storage heating operation in which the outdoor heat exchanger functions as an evaporator. , and indoor heat exchanger The condenser , storage a heat storage temperature sensor that detects a temperature of a heat storage material; and a control unit that controls a plurality of expansion valves, one of the plurality of expansion valves being a first expansion valve provided upstream of a heat storage heat exchanger that functions as a condenser. Considering the condensation temperature of the indoor heat exchanger The method includes the steps of: setting a first slope indicating the amount of heat stored per unit time in the heat storage heat exchanger; detecting a second slope indicating the amount of rise per unit time in temperature of the heat storage material stored during heat storage heating operation; comparing the second slope with the first slope; and controlling the opening of the first expansion valve based on the result of the comparison. Effect of the Invention

[0014] According to the present invention, it is possible to store the heat required for defrosting while suppressing a decrease in user comfort when performing a defrosting operation, and to avoid an increase in costs when achieving both of these. [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] 4 is a graph showing an example of a temperature change when the refrigeration cycle device according to the embodiment of the present invention stores heat in a heat storage heat exchanger. [Figure 4] 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 cooling operation. [Diagram 5] 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 heat storage heating 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 defrosting heating 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 flow of a process for storing, in a heat storage heat exchanger, heat used when performing a defrosting operation 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, an expansion valve 5 (51, 52, 53), and a switching valve 6 (61, 62) are connected, and which circulates the refrigerant. The refrigeration cycle apparatus S also includes a control unit 7 that controls the expansion valve 5 and the switching valve 6.

[0017] Here, the refrigerant circuit C of the refrigeration cycle apparatus S in the embodiment of the present invention will be described with reference to Fig. 1. The refrigerant circuit C is composed of each device such as the compressor 1 described above, and a flow path through which the refrigerant flows that connects these devices. For example, when the refrigeration cycle apparatus S performs a heating operation, the refrigerant discharged from the compressor 1 flows through the indoor heat exchanger 2 and the outdoor heat exchanger 3 in this order, and is then sucked into the compressor 1. A first switching valve 61 is provided in the flow path connecting the compressor 1 and the indoor heat exchanger 2 during the heating operation, and a third expansion valve 53 is provided in the flow path connecting the indoor heat exchanger 2 and the outdoor heat exchanger 3.

[0018] Also, for example, when the refrigeration cycle apparatus S performs a heat storage heating operation described later, 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 from the heat storage heat exchanger 4 flows to the outdoor heat exchanger 3 via the second expansion valve 52 and a junction C1 provided in the flow path between the second expansion valve 52 and the outdoor heat exchanger 3, and is then sucked into the compressor 1. In addition, the first expansion valve 51 and the 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. In addition, the second expansion valve 52 is provided in the flow path connecting the heat storage heat exchanger 4 and the junction C1.

[0019] 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 B connected to a flow path between the first expansion valve 51 and the second switching valve 62. The bypass circuit B is provided between the first switching valve 61 and the second switching valve 62. The bypass circuit B is provided with a check valve and the like so that the refrigerant flows only in the direction of the arrow as shown in FIG.

[0020] When the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2, the bypass circuit B is connected to the suction side of the compressor 1. On the other hand, when the refrigerant discharged from the compressor 1 flows into the bypass circuit B that 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.

[0021] 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 to the outdoor heat exchanger 3. When the refrigerant discharged from the compressor 1 flows to the heat-storage heat exchanger 4, the outdoor heat exchanger 3 and the suction side of the compressor 1 are connected. On the other hand, when the refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3, the heat-storage heat exchanger 4 and the suction side of the compressor 1 are connected.

[0022] The compressor 1 compresses the refrigerant circulating through the refrigerant circuit C. The indoor heat exchanger 2 exchanges heat between the indoor air and the refrigerant. The outdoor heat exchanger 3 exchanges heat between the outdoor air and the refrigerant. Although explanations of the types of the compressor 1, the indoor heat exchanger 2, and the outdoor heat exchanger 3 will be omitted here, various types of equipment can be adopted.

[0023] In addition, the indoor heat exchanger 2 in the embodiment of the present invention is provided with a condensation temperature sensor 21 that detects the condensation temperature of the refrigerant during heating operation or heat storage heating operation. The condensation temperature of the refrigerant detected by the condensation temperature sensor 21 is used to control the opening degree of the first expansion valve 51 when storing heat in the heat storage heat exchanger 4 described later.

[0024] Further, the outdoor heat exchanger 3 is provided with an outdoor air temperature sensor 31 that detects the outdoor air temperature. The outdoor air temperature sensor 31 detects the temperature of air flowing into the outdoor heat exchanger 3. The outdoor air temperature detected by the outdoor air temperature sensor 31 is used to control the opening degree of the first expansion valve 51 when storing heat in the heat storage heat exchanger 4 described later.

[0025] The heat storage heat exchanger 4 is a heat exchanger in which heat is exchanged between the heat storage material and the refrigerant passing through the heat storage heat exchanger 4. The heat storage heat exchanger 4 is, for example, a fin-and-tube type heat exchanger. The heat storage heat exchanger 4 is disposed in a heat storage container filled with a heat storage material.

[0026] The heat storage material may be liquid or solid, as long as it can exchange heat with the refrigerant flowing inside the heat storage heat exchanger 4 and store heat. Therefore, for example, when the heat storage material is liquid, the heat storage heat exchanger 4 is immersed in the heat storage material filled in the heat storage container. In other words, the periphery of the heat storage heat exchanger 4 is covered with the heat storage material. The heat supplied from the refrigerant is stored in this heat storage material, and the stored heat is used for defrosting operation as described later.

[0027] In addition, a heat storage temperature sensor HS, which will be described later, is provided at a position where it can measure the temperature of the heat storage material. For example, when a heat storage container in which a heat storage heat exchanger is disposed is placed on a horizontal ground surface, the heat storage temperature sensor HS is disposed so as to be located approximately at the center in the height direction of the heat storage material filled in the heat storage container.

[0028] This is because when heat exchange occurs between the heat storage material and the heat storage heat exchanger 4, particularly when the heat storage material is liquid, a temperature gradient may occur in the height direction due to convection, etc. Therefore, if the heat storage temperature sensor HS is placed at the top or bottom in the height direction, the temperature of the heat storage material may be detected as high or low. Therefore, in order to detect an approximately average value of the temperature of the heat storage material measured by the heat storage temperature sensor, the heat storage temperature sensor is placed approximately in the center of the height direction of the heat storage material, as described above.

[0029] The heat storage temperature sensor HS may be only one or may be multiple. When multiple heat storage temperature sensors HS are provided, the detected temperature of the heat storage material may be calculated, for example, by taking the average value of the values ​​detected by the heat storage temperature sensors HS as the temperature of the heat storage material, and may be used to control the opening degree of the expansion valve, which will be described later.

[0030] The opening degree of the expansion valve 5 can be adjusted based on an instruction from a control unit 7 described later, and a plurality of expansion valves are provided in the refrigeration cycle apparatus S in the embodiment of the present invention. Specifically, three expansion valves are provided, and a first expansion valve 51 is provided upstream in the refrigerant flow direction when the heat storage heat exchanger 4 functions as a condenser.

[0031] The second expansion valve 52 is provided between the heat storage heat exchanger 4 and the above-mentioned junction C1 in the refrigerant circuit C. That is, the second expansion valve 52 is provided downstream in the direction in which the refrigerant flows 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 in which the refrigerant flows when the indoor heat exchanger 2 functions as a condenser.

[0032] 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 switches the refrigerant between flowing to the indoor heat exchanger 2 and flowing to the bypass circuit B. On the other hand, the second switching valve 62 switches the refrigerant between flowing to the heat storage heat exchanger 4 and flowing to the outdoor heat exchanger 3.

[0033] In the refrigeration cycle apparatus S according to the embodiment of the present invention, two switching valves 6 are provided. That is, a first switching valve 61 is provided between the compressor 1 and the indoor heat exchanger 2. In addition, a second switching valve 62 is provided between the compressor 1 and the outdoor heat exchanger 3 or the heat storage heat exchanger 4.

[0034] In the following, when these three expansion valves 51, 52, and 53 are collectively described, they are referred to as "expansion valve 5," and when each expansion valve is described individually, they are referred to by their respective names. Similarly, when these two switching valves 61 and 62 are collectively described, they are referred to as "switching valve 6," and when each switching valve is described individually, they are referred to by their respective names.

[0035] Furthermore, in the refrigeration cycle apparatus 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. However, the operation for melting the frost adhering to the outdoor heat exchanger 3 is referred to as a "defrosting operation" rather than a "defrosting heating operation".

[0036] The control unit 7 controls the opening degree of the multiple expansion valves 5. The control unit 7 controls the opening degree of each expansion valve, 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.

[0037] 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 expansion valves 5 and the multiple switching valves 6. The control unit 7 also controls a defrosting operation for the outdoor heat exchanger 3 that is performed in parallel with the heating operation.

[0038] 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 setting unit 72, a storage unit 73, a determination unit 74, and an expansion valve opening control unit 75.

[0039] 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 constantly transmitted from the heat storage temperature sensor HS to the temperature detection unit 71. Alternatively, conversely, the temperature detection unit 71 may obtain the temperature from the heat storage temperature sensor HS as necessary.

[0040] The temperature detection unit 71 also acquires the outdoor air temperature detected by the outdoor air temperature sensor 31 provided in the outdoor heat exchanger 3. The outdoor air temperature may also be constantly transmitted from the outdoor air temperature sensor 31 to the temperature detection unit 71, or the temperature detection unit 71 may obtain the outdoor air temperature from the outdoor air temperature sensor 31 as necessary.

[0041] Furthermore, the condensation temperature of the indoor heat exchanger 2 detected by the condensation temperature sensor 21 provided in the indoor heat exchanger 2 is also acquired by the temperature detection unit 71. The temperature of the heat storage material, the outside air temperature, or the condensation temperature of the indoor heat exchanger 2 is used in control when storing heat in the heat storage heat exchanger 4.

[0042] Here, in the refrigeration cycle apparatus S according to the embodiment of the present invention, a heat-storage heating operation is performed in which heat is stored in the heat-storage heat exchanger 4 at the same time as the heating operation. The heat of the refrigerant discharged from the compressor 1 is stored in the heat-storage heat exchanger 4 in order to be used when removing frost adhering to the outdoor heat exchanger 3.

[0043] Therefore, before a defrosting operation in a defrosting heating operation that is appropriately performed between heat-storage heating operations, it is necessary to store heat to be used in the defrosting operation in the heat-storage heat exchanger 4. In other words, between successive defrosting operations, during a heating operation that is performed from the end of a previous defrosting operation to the start of a subsequent defrosting operation, it is necessary to store sufficient heat in the heat-storage heat exchanger 4 to be used in the subsequent defrosting operation.

[0044] Heat is stored in the heat storage heat exchanger 4 by controlling the refrigerant discharged from the compressor 1 during heat storage heating operation so that it flows not only into the indoor heat exchanger 2 but also into the heat storage heat exchanger 4. Specifically, this is performed by an expansion valve opening control unit 75, which will be described later, controlling the opening of a first expansion valve 51 provided upstream of the heat storage heat exchanger 4. The expansion valve opening control unit 75 controls the opening of the first expansion valve 51, thereby adjusting the speed of heat storage in the heat storage heat exchanger 4.

[0045] 3 is a graph showing an example of temperature change when the refrigeration cycle apparatus S according to the embodiment of the present invention stores heat in the heat storage heat exchanger 4. In the graph shown in Fig. 3, the vertical axis represents temperature (°C) and the horizontal axis represents time (min). The temperature on the vertical axis represents the condensation temperature of the indoor heat exchanger 2 and the temperature of the heat storage material in the heat storage heat exchanger 4.

[0046] Specifically, the dashed straight line at the top of the graph indicates the condensation temperature of the indoor heat exchanger 2, which is shown here as a value that does not change over time. Meanwhile, the solid line extending diagonally from the bottom left to the top right of the graph indicates the temperature of the heat storage material, which shows that the temperature of the heat storage material gradually increases over time due to heat exchange between the refrigerant flowing in from the compressor 1 and the heat storage material.

[0047] The temperature of the heat storage material is low near time t0. This is because the temperature of the heat storage material has dropped as a result of the heat stored in the heat storage heat exchanger 4 during the previous defrosting operation described above being utilized. From this state, the heat to be utilized during the subsequent defrosting operation is stored in the heat storage material.

[0048] The maximum temperature of the heat storage material depends on the condensation temperature of the indoor heat exchanger 2. The condensation temperature of the indoor heat exchanger 2 is also a value that depends on the temperature set by the user in the indoor unit and the air volume of the indoor fan. Therefore, when the condensation temperature of the indoor heat exchanger 2, shown by the dashed line in Fig. 3, changes, the maximum temperature of the heat storage material also changes.

[0049] Since the maximum temperature of the heat storage material depends on the condensation temperature of the indoor heat exchanger 2, in an embodiment of the present invention, the target amount of heat to be stored in the heat storage material is set not by setting the temperature of the heat storage material as a numerical value, but by setting the slope at which the temperature of the heat storage material rises.

[0050] Furthermore, when frost forms on the outdoor heat exchanger 3, the speed at which frost forms is related to the outdoor air temperature and humidity. Looking at the outdoor air temperature, for example, when the outdoor air temperature drops, frost forms on the outdoor heat exchanger 3, but when the outdoor air temperature drops by more than a certain temperature, the amount of moisture contained in the outdoor air also decreases, and the absolute humidity also drops, so the speed at which frost forms slows down. On the other hand, when the outdoor air temperature is high, frost does not form on the outdoor heat exchanger 3 in the first place, and there is no need for defrosting operation. Therefore, in many cases, the speed at which frost forms is said to be fastest when the outdoor air temperature is around 2°C, for example.

[0051] Therefore, when the outdoor air temperature is around 2°C, it becomes necessary to perform defrosting operation at short time intervals, and the time required to store the heat required for defrosting operation in the heat storage material becomes short. Therefore, the gradient of the temperature rise in the heat storage material becomes steep. On the other hand, when the outdoor air temperature is very low as described above, or conversely, when it is high, the speed of frost formation slows down, so that defrosting operation is not performed frequently between heating heat storage operations, and the time between the preceding and following defrosting operations can be secured longer. Therefore, even if the gradient of the temperature rise in the heat storage material is set to be gentle, the heat to be used in the defrosting operation can be sufficiently stored.

[0052] 3, the slope of the temperature rise becomes gentler as time passes and the temperature approaches the condensation temperature of the indoor heat exchanger 2. This is because, as the temperature of the heat storage material approaches the condensation temperature of the indoor heat exchanger 2 due to the rise in the temperature of the heat storage material, the difference between the condensation temperature of the refrigerant in the heat storage heat exchanger 4 and the temperature of the heat storage material becomes smaller, and the amount of heat exchange in the heat storage heat exchanger 4 decreases.

[0053] The setting unit 72 sets an index relating to the speed at which heat is stored in the heat storage material arranged in the heat storage heat exchanger 4. This index is the slope at which the temperature of the heat storage material increases, and this slope will be referred to as the "first slope" hereinafter.

[0054] As described above, the first gradient set by the setting unit 72 is set using the temperature of the heat storage material, the condensation temperature of the refrigerant in the indoor heat exchanger 2, and the outdoor air temperature detected by the outdoor air temperature sensor 31. That is, the first gradient is set based on the information on these temperatures so that, between successive defrosting operations, sufficient heat to be used in the subsequent defrosting operation can be stored in the heat storage heat exchanger 4 during the heating heat storage operation from the end of the previous defrosting operation to the start of the subsequent defrosting operation.

[0055] Therefore, during heat storage heating operation, the control unit 7 controls the opening degree of the first expansion valve 51 so that the temperature rise of the heat storage material follows the first gradient, thereby adjusting the amount of refrigerant flowing into the heat storage heat exchanger 4.

[0056] Here, the first gradient is set, for example, as follows in the setting unit 72. That is, when the defrosting operation is performed, the amount of heat required to melt the frost on the outdoor heat exchanger 3 needs to be stored in the heat storage heat exchanger 4 in the heating heat storage operation, but as described above, the upper limit of the temperature when storing heat in the heat storage material depends on the condensation temperature in the indoor heat exchanger 2. Therefore, the amount of heat (amount of heat storage) stored in the heat storage material is set so that the amount of heat required in the defrosting heating operation can be stored regardless of the high or low condensation temperature.

[0057] That is, in the refrigeration cycle apparatus S according to the embodiment of the present invention, heat is stored in the heat storage material during heating heat storage operation, and this heat is used in the defrosting operation. Therefore, it is assumed that the condensation temperature in the indoor heat exchanger 2 is higher than the melting temperature of the frost adhering to the outdoor heat exchanger 3. In addition, the amount of heat given to the heat storage material per unit time differs depending on the condensation temperature.

[0058] For example, when the condensation temperature is low, the amount of heat given to the heat storage material is small, so the gradient of the temperature rise of the heat storage material is gentle. In such a case, in order to shorten the time required to store the amount of heat required for defrosting operation in the heat storage material, it is necessary to increase the amount of refrigerant flowing into the heat storage heat exchanger 4 so that the gradient of the temperature rise becomes steeper.

[0059] This amount of stored heat (J) can be calculated by (amount of heat (J) required to melt the frost on the outdoor heat exchanger 3 + amount of heat (J) required for defrosting and heating operation) + (target heating capacity during defrosting (W) - power consumption of compressor (W)) x defrosting time (S). This amount of stored heat needs to be stored during the heating and heat storage operation in order to be used in the defrosting and heating operation that follows the heating and heat storage operation.

[0060] Therefore, in order to store the necessary amount of heat within the time of this heating heat storage operation, a first slope is set using the amount of heat storage and time. By setting the first slope in this way, the necessary amount of heat can be stored within the time of heating heat storage operation regardless of the high or low condensation temperature. Note that since the first slope is set in this way, it can be said to be merely a theoretical value.

[0061] Since the amount of frost on the outdoor heat exchanger 3 varies depending on the outdoor air temperature, the time until the defrosting operation is completed also varies. Therefore, a correction coefficient is calculated in advance based on, for example, the actual measurement value of the frost rate for each outdoor air temperature, and is stored in, for example, the storage unit 73 described next.

[0062] In addition, by correcting the above-mentioned first slope using a correction coefficient based on the outside air temperature acquired from the outside air temperature sensor 31 via the temperature detection unit 71, a more accurate first slope can be set.

[0063] As a method for correcting the first gradient, for example, the following method is conceivable. That is, for example, it is conceivable to correct the first gradient based on a reference frost formation rate for the outdoor heat exchanger 3. Specifically, for example, assuming that the frost formation rate is fastest when the outdoor air temperature is 2°C, the setting unit 72 may correct the first gradient using the formula: corrected first gradient = uncorrected first gradient × (frost formation rate at current outdoor air temperature (°C) / frost formation rate when the outdoor air temperature is 2°C).

[0064] The storage unit 73 is composed of, for example, a semiconductor or a magnetic disk, and stores the first gradient set by the setting unit 72 based on each temperature acquired by the above-mentioned temperature detection unit 71. In addition, a correction formula using the frost formation rate at the reference outside air temperature as described above may be stored.

[0065] The judgment unit 74 uses the temperature of the heat storage material obtained by the temperature detection unit 71 from the heat storage temperature sensor HS as described above to calculate the amount of increase in the temperature of the heat storage material per unit time as a slope (hereinafter, this calculated slope will be referred to as the “second slope”).

[0066] The determination unit 74 calculates the second slope using the latest heat storage material temperature detected by the heat storage temperature sensor HS and, for example, the most recent temperature of the heat storage material detected before the latest heat storage material temperature was detected. Specifically, the calculation is performed using the formula: (latest heat storage material temperature-previously detected heat storage material temperature) / unit time. Therefore, the second slope is an actual measurement value.

[0067] The most recent temperature of the heat storage material may be stored in the determination unit 74, or the determination unit 74 may acquire information stored in the storage unit 73 from the storage unit 73, for example.

[0068] Then, the determination unit 74 compares this second slope with the first slope stored in the storage unit 73 to determine whether the second slope matches the first slope. By comparing the second slope, which is the amount of temperature rise (actual measured value) when heat of the refrigerant discharged from the compressor 1 is actually stored in the heat storage material, with the first slope, which is a theoretical value set with the above-mentioned intention, the rate of heat storage can be adjusted so that heat is stored in the heat storage material as planned.

[0069] In other words, the control unit 7 controls the opening degree of the first expansion valve 51 so that the second slope, which indicates the amount of increase per unit time in the temperature of the heat storage material stored during heat storage heating operation, matches the first slope based on the first slope.

[0070] Specifically, when the judgment unit 74 compares the second slope with the first slope, if the second slope is greater than the first slope, this means that heat is being stored in the heat storage material faster than the planned rate of heat storage, and therefore the expansion valve opening control unit 75 described later controls the opening of the first expansion valve 51 to be reduced.

[0071] On the other hand, when the first gradient is larger than the second gradient, the rate of heat storage in the heat storage material is slower than the scheduled rate of heat storage, so the expansion valve opening control unit 75 controls to increase the opening of the first expansion valve 51. By performing such control, more refrigerant discharged from the compressor 1 flows into the heat storage heat exchanger 4.

[0072] When the second gradient and the first gradient are substantially the same, the expansion valve opening control unit 75 performs control to maintain the opening of the first expansion valve 51. This is because heat is being stored in the heat storage material as planned.

[0073] Therefore, in order to more accurately manage the rate of heat storage in the heat storage material, the determination unit 74 can frequently calculate the second slope and compare it with the first slope. Note that the frequency at which the determination unit 74 calculates the second slope can be set arbitrarily.

[0074] The determination result in the determination unit 74 is transmitted to the expansion valve opening control unit 75. The expansion valve opening control unit 75 controls the opening of the first expansion valve 51 in accordance with the determination result received from the determination unit 74.

[0075] The functions of the control unit 7 of the refrigeration cycle apparatus S in the embodiment of the present invention have been described above. Next, the operation modes of the refrigeration cycle apparatus S will be described in order with reference to the circuit diagrams of the refrigeration cycle apparatus S in the embodiment of the present invention shown in Figs. 4 to 6.

[0076] In the circuit diagrams shown in Figures 4 to 6, the refrigerant circuits C through which the refrigerant actually flows are indicated by solid lines. On the other hand, the refrigerant circuits C through which the refrigerant does not flow are indicated by dashed lines. The direction of the refrigerant flowing in the refrigerant circuits C is indicated by arrows.

[0077] First, the cooling operation will be described. Fig. 4 is a refrigerant circuit diagram showing the flow of refrigerant when the refrigeration cycle device S according to the embodiment of the present invention performs the cooling operation. During the cooling operation, the indoor heat exchanger 2 functions as an evaporator, and the outdoor heat exchanger 3 functions as a condenser.

[0078] That is, the refrigerant compressed in 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 arrow in Fig. 4. Note that at this time, the first expansion valve 51 is fully open. The refrigerant discharged from the compressor 1 also flows through the first switching valve 61, but also passes through the bypass circuit B and flows into the outdoor heat exchanger 3 from the second switching valve 62.

[0079] The refrigerant that has flowed into the outdoor heat exchanger 3 is cooled by outdoor air that is supplied by the rotation of an outdoor fan (not shown), and dissipates heat to the outdoor air. Then, a part or all of the refrigerant is condensed.

[0080] The refrigerant that has thus released heat to the outside air flows out of the outdoor heat exchanger 3 and passes through the third expansion valve 53, where it is decompressed to become a low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant then flows into the indoor heat exchanger 2, where it exchanges heat with the indoor air.

[0081] 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 21 is cooled and supplied to the room by the indoor fan to cool the room. Then, the refrigerant that has absorbed heat through heat exchange flows into the compressor 1 via the first switching valve 61.

[0082] On the other hand, the flow of the refrigerant when the refrigeration cycle apparatus S performs a 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 a heat-storage heating operation.

[0083] As shown in Fig. 5, 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.

[0084] The refrigerant flowing out of the indoor heat exchanger 2 flows into the outdoor heat exchanger 3 via the third expansion valve 53. The outdoor heat exchanger 3 functions as an evaporator, and heat is exchanged between the refrigerant and the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 3 flows into the compressor 1 via the second switching valve 62.

[0085] 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. At this time, the opening degree of the first expansion valve 51 is adjusted based on the control described later.

[0086] 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 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.

[0087] The refrigerant flowing out from the heat storage heat exchanger 4 flows into the outdoor heat exchanger 3 via the second expansion valve 52, and then flows out from the outdoor heat exchanger 3 and into the compressor 1 via the second changeover valve 62. At this time, the opening degree of the second expansion valve 52 is adjusted to a predetermined fixed opening degree. Specifically, the opening degree is set so that the amount of refrigerant flowing into the heat storage heat exchanger 4 is smaller than the amount of refrigerant flowing into the indoor heat exchanger 2.

[0088] 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 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 operation is heating here, the indoor heat exchanger 2 functions as a condenser, and exchanges heat between the refrigerant and the air flowing into the indoor unit in the indoor heat exchanger 2, and supplies the warmed air that has absorbed heat from the refrigerant to the indoor space.

[0089] 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. At this time, the opening degree of the first expansion valve 51 is adjusted based on control described later. When high-temperature refrigerant from the compressor 1 flows into the outdoor heat exchanger 3, a defrosting operation is performed to melt frost adhering to the outdoor heat exchanger 3.

[0090] The refrigerant flowing out from 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 from 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 is performed between the flowing in refrigerant and the heat storage material. The refrigerant flowing out from the heat storage heat exchanger 4 flows into the compressor 1 via the second switching valve 62.

[0091] [Operation] Next, the flow of control of the refrigeration cycle apparatus S by the control unit 7 in the above-mentioned heat-storage heating operation and defrost heating operation will be described with reference to Fig. 7 and Fig. 8. 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. Fig. 8 is a flowchart showing the flow of a process for storing, in the heat-storage heat exchanger 4, heat used when performing the defrosting operation in the refrigeration cycle apparatus S according to the embodiment of the present invention.

[0092] 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 unit 7 judges whether or not the conditions are met. As a condition for starting the heat storage heating operation, for example, a condition that the difference between the heat storage material temperature and the outside air temperature is less than a predetermined value is set. This allows the heat storage heating operation to be executed when the amount of stored heat is insufficient.

[0093] When the heat storage heating operation is started, as described above, the refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 via the first switching valve 61, and also flows into the heat storage heat exchanger 4 via the first expansion valve 51 and the second switching valve 62. At that time, the control unit 7 adjusts the amount of refrigerant flowing into the heat storage heat exchanger 4, for example, by controlling the opening degree of the first expansion valve 51 (ST2).

[0094] In addition, the opening degree of the first expansion valve 51 at the start of the heat storage heating operation may be controlled by the expansion valve opening control unit 75 simultaneously with the start of the heat storage heating operation, for example, so that it becomes a preset opening degree at the start of the heat storage heating operation.

[0095] Alternatively, for example, when the defrosting heating operation is performed before the heat storage heating operation is started, the defrosting operation is performed on the outdoor heat exchanger 3, and therefore the first expansion valve 51 is adjusted to an opening degree required for the defrosting operation. Therefore, it is also possible to set the opening degree of the first expansion valve 51 at the start of the heat storage heating operation to the opening degree during the defrosting operation.

[0096] Based on the opening degree of the first expansion valve 51 at the start of the above-mentioned heat storage heating operation, the opening degree of the first expansion valve 51 is adjusted as necessary in accordance with the change over time in the temperature of the heat storage material, as described below, to adjust the rate of heat storage in the heat storage heat exchanger 4.

[0097] Specifically, the opening degree of the first expansion valve 51 is determined according to the flow shown in Fig. 8. That is, first, the setting unit 72 sets the first gradient from the temperature of the heat storage material, the condensation temperature of the indoor heat exchanger 2, and the outdoor air temperature (ST11). As described above, the temperature of the heat storage material is obtained from the heat storage temperature sensor HS. The condensation temperature of the indoor heat exchanger 2 is obtained from the condensation temperature sensor 21 provided in the indoor heat exchanger 2. Moreover, the outdoor air temperature is obtained from the outdoor air temperature sensor 31.

[0098] These temperatures are acquired by temperature detection unit 71. Setting unit 72 sets the first gradient using the temperatures acquired by temperature detection unit 71, for example, by the method described above, and stores the first gradient in storage unit 73.

[0099] Next, the determination unit 74 calculates a second slope indicating the amount of increase in the temperature of the heat storage material per unit time from the current temperature of the heat storage material acquired by the temperature detection unit 71 and the most recent temperature of the heat storage material (ST12).Then, the determination unit 74 compares this second slope with the first slope stored in the memory unit 73 (ST13).

[0100] When the judgment unit 74 compares the second slope with the first slope (ST14) and finds that the second slope is greater than the first slope (YES in ST14), this means that heat is being stored in the heat storage material faster than the planned heat storage rate, so the expansion valve opening control unit 75 controls the opening of the first expansion valve 51 to be smaller (ST15).

[0101] On the other hand, if the first slope is equal to or greater than the second slope (NO in ST14), the determination unit 74 then determines whether the second slope is equal to the first slope (ST16). Note that the second slope being equal to the first slope here does not only mean that they are completely equal, but may also mean that the difference between the second slope and the first slope is included in a range in which they can be considered equal, for example, that is set in advance.

[0102] When the determination unit 74 determines that the second gradient and the first gradient are equal (YES in ST16), the expansion valve opening control unit 75 performs control to maintain the opening of the first expansion valve 51 (ST17). This is because heat is being stored in the heat storage material as planned.

[0103] On the other hand, when the determination unit 74 determines that the second slope and the first slope are not equal (NO in ST16), this corresponds to a case where the second slope is smaller than the first slope. That is, in this case, the rate of heat storage in the heat storage material is slower than the scheduled rate of heat storage, so that the expansion valve opening control unit 75 controls the first expansion valve 51 to increase the opening so that more refrigerant discharged from the compressor 1 flows into the heat storage heat exchanger 4 (ST18).

[0104] 8 shows a flow of controlling the opening degree of the first expansion valve 51 in a case where the magnitude of the second gradient and the first gradient is determined once. However, when the rate of heat storage in the heat storage heat exchanger 4 is to be precisely controlled, as described above, the determination unit 74 needs to calculate the second gradient multiple times and appropriately compare it with the first gradient.

[0105] Therefore, the frequency with which the determination unit 74 calculates the second gradient can be set arbitrarily. Then, in order to store heat according to the change in temperature of the heat storage material over time, the opening degree of the first expansion valve 51 is once set, and then the process returns to step ST12 to calculate the second gradient again, and control is performed according to the above-mentioned flow. In this way, while the heat storage heating operation is being performed, the necessary heat is stored in the heat storage heat exchanger 4 while the opening degree of the first expansion valve 51 is adjusted.

[0106] While the heat storage heating operation is being performed, the control unit 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 (ST3 in FIG. 7). If the defrosting operation is not required (NO in ST3), the heat storage heating operation continues.

[0107] On the other hand, when the control unit 7 determines that the conditions for starting the defrosting heating operation are met (YES in ST3), the defrosting heating operation is started (ST4). 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. While the defrosting heating operation is being performed, the control unit 7 determines whether the frost on the outdoor heat exchanger 3 has melted and it is acceptable to end the defrosting heating operation based on a preset end condition (ST5).

[0108] If the control unit 7 determines that the frost on the outdoor heat exchanger 3 has not melted sufficiently and the defrosting heating operation cannot be terminated yet (NO in ST5), the defrosting heating operation that is being executed continues. On the other hand, if the control unit 7 determines that the defrosting heating operation can be terminated (YES in ST5), the defrosting heating operation is terminated (ST6).

[0109] Although not shown in the flowchart of FIG. 7, after the defrosting heating operation is completed, the heating and heat storage operation may be started again.

[0110] As described above, by controlling the opening degree of the first expansion valve 51 so as to match the second slope to the preset first slope, it is possible to achieve a balanced allocation of the heat used for heating and the heat used for defrosting, while storing the amount of heat required for defrosting before the defrost heating operation is started.

[0111] Therefore, it is possible to provide a refrigeration cycle device and a control method for a refrigeration cycle device that can store the heat required for defrosting while suppressing a decrease in user comfort when performing defrosting heating operation, and avoid increased costs when achieving both of these.

[0112] That is, when storing heat in the heat storage heat exchanger 4 during the heat storage heating operation, the opening degree of the first expansion valve is adjusted, and the control of the opening degree of the first expansion valve is performed based on the temperature of the heat storage material. Therefore, for example, even if the heat storage heat exchanger is structured to be placed in a heat storage container filled with the heat storage material, the speed of heat storage in the heat storage heat exchanger can be appropriately controlled as long as the temperature of the heat storage material can be detected.

[0113] In addition, in order to detect the condensation temperature in the heat storage heat exchanger, for example, in the embodiment of the present invention, a condensation temperature sensor 21 that detects the condensation temperature of the refrigerant is provided in the indoor heat exchanger 2. Therefore, for example, since it is no longer necessary to provide a pressure sensor in the high pressure side circuit to detect the condensation temperature from the condensation pressure, it is possible to store heat in the heat storage heat exchanger while suppressing increases in costs.

[0114] 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.

[0115] 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.

[0116] For example, up to this point, we have given an example of a defrosting operation using heat stored in a heat storage heat exchanger, in which a defrosting heating operation is performed. However, the content described so far can also be applied, for example, when switching from heat storage heating operation to defrosting operation (defrosting operation without simultaneous heating operation) to defrost the outdoor heat exchanger.

[0117] Also, the first gradient has been described on the assumption that the setting unit 72 sets it each time to store the required amount of heat in the heat-storage heat exchanger 4. However, the first gradient may be set to a fixed value, for example.

[0118] The techniques described in the embodiments of the present invention may also be configured as follows. (1) A refrigerant circuit that circulates a 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 expansion valves whose opening degrees are adjustable; a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger functions as an evaporator; and the indoor heat exchanger The condenser ,before a defrosting operation in which the heat storage heat exchanger functions as an evaporator; and a plurality of switching valves that switch a circulation path of the refrigerant in the refrigerant circuit according to the defrosting operation in which the heat storage heat exchanger functions as an evaporator. A heat storage temperature sensor for detecting the temperature of the heat storage material; A control unit that controls the plurality of expansion valves, one of the plurality of expansion valves is a first expansion valve provided upstream of the heat storage heat exchanger functioning as the condenser; The control unit determines whether a second slope indicating an amount of increase per unit time of the temperature of the heat storage material stored during the heat storage heating operation is: In view of the condensation temperature of the indoor heat exchanger A refrigeration cycle device, comprising: a refrigeration cycle control unit that controls an opening degree of the first expansion valve so as to coincide with a preset first gradient. (2) The refrigeration cycle device according to (1) above, characterized in that the heat storage heat exchanger is disposed in a heat storage container filled with the heat storage material. (3) The outdoor heat exchanger includes an outdoor air temperature sensor for detecting an outdoor air temperature, The refrigeration cycle device according to (1) or (2) above, wherein the first gradient is set in accordance with the outside air temperature detected by the outside air temperature sensor. (4) A refrigeration cycle device as described in any of (1) to (3) above, characterized in that one of the multiple expansion valves is a second expansion valve provided downstream of the heat storage heat exchanger functioning as the condenser, and the control unit controls the opening degree of the second expansion valve during the heat storage heating operation to be a predetermined opening degree. (5) A refrigerant circuit that circulates a 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 expansion valves whose opening degrees are adjustable; a heat storage heating operation in which the indoor heat exchanger and the heat storage heat exchanger function as a condenser and the outdoor heat exchanger functions as an evaporator; and the indoor heat exchanger The condenser ,before a defrosting operation in which the heat storage heat exchanger functions as an evaporator; and a plurality of switching valves that switch a circulation path of the refrigerant in the refrigerant circuit according to the defrosting operation in which the heat storage heat exchanger functions as an evaporator. A heat storage temperature sensor for detecting the temperature of the heat storage material; A control unit that controls the plurality of expansion valves, A refrigeration cycle apparatus, wherein one of the plurality of expansion valves is a first expansion valve provided upstream of the heat storage heat exchanger functioning as the condenser, During heat storage heating operation, The amount of heat required for the defrosting operation for the outdoor heat exchanger In view of the condensation temperature of the indoor heat exchanger Setting a first slope indicating an amount of heat stored per unit time in the heat storage heat exchanger; Detecting a second slope indicating an amount of increase per unit time of the temperature of the heat storage material stored during the heat storage heating operation, and comparing the second slope with the first slope; controlling an opening degree of the first expansion valve based on a result of the comparison; A control method for a refrigeration cycle device comprising: (6) The outdoor heat exchanger includes an outdoor air temperature sensor for detecting an outdoor air temperature, The control method for a refrigeration cycle apparatus described in (5) above, characterized in that in the step of setting the first slope, the first slope is set according to the outside air temperature detected by the outside air temperature sensor. (7) One of the plurality of expansion valves is a second expansion valve provided downstream of the heat storage heat exchanger functioning as the condenser, The control method for a refrigeration cycle device described in (5) or (6) above, characterized in that the control unit includes a step of controlling the opening degree of the second expansion valve to a predetermined opening degree during the heat storage heating operation. [Explanation of symbols]

[0119] REFERENCE SIGNS LIST 1 compressor, 2 indoor heat exchanger, 3 outdoor heat exchanger, 31 outdoor air temperature sensor, 4 heat storage heat exchanger, 5 expansion valve, 51 first expansion valve, 52 second expansion valve, 53 third expansion valve, 6 changeover valve, 61 first changeover valve, 62 second changeover valve, 7 control unit, 71 temperature detection unit, 72 setting unit, 73 memory unit, 74 determination unit, 75 expansion valve opening 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 expansion valves whose opening degrees are adjustable; a plurality of switching valves are connected to switch a circulation path of the refrigerant in the refrigerant circuit between a heat storage 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 and the indoor heat exchanger function as a condenser and the heat storage heat exchanger function as an evaporator; A heat storage temperature sensor for detecting the temperature of the heat storage material; A control unit that controls the plurality of expansion valves, one of the plurality of expansion valves is a first expansion valve provided upstream of the heat storage heat exchanger functioning as the condenser, The control unit controls the opening degree of the first expansion valve so that a second slope indicating the amount of increase per unit time of the temperature of the heat storage material stored during the heat storage heating operation coincides with a first slope that is set in advance in consideration of the condensation temperature of the indoor heat exchanger.

2. 2. The refrigeration cycle apparatus according to claim 1, wherein the heat storage heat exchanger is disposed in a heat storage container filled with the heat storage material.

3. The outdoor heat exchanger includes an outdoor air temperature sensor for detecting an outdoor air temperature, 2. The refrigeration cycle apparatus according to claim 1, wherein the first gradient is set in accordance with the outside air temperature detected by the outside air temperature sensor.

4. 4. A refrigeration cycle device as described in any one of claims 1 to 3, characterized in that one of the plurality of expansion valves is a second expansion valve provided downstream of the heat storage heat exchanger functioning as the condenser, and the control unit controls the opening degree of the second expansion valve during the heat storage heating operation to be a predetermined opening degree.

5. 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 expansion valves whose opening degrees are adjustable; a plurality of switching valves are connected to switch a circulation path of the refrigerant in the refrigerant circuit between a heat storage 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 and the indoor heat exchanger function as a condenser and the heat storage heat exchanger function as an evaporator; A heat storage temperature sensor for detecting the temperature of the heat storage material; A control unit that controls the plurality of expansion valves, A refrigeration cycle apparatus, wherein one of the plurality of expansion valves is a first expansion valve provided upstream of the heat storage heat exchanger functioning as the condenser, During heat storage heating operation, setting a first gradient indicating a heat storage amount per unit time for storing in the heat storage heat exchanger a heat amount required for the defrosting operation on the outdoor heat exchanger in consideration of a condensation temperature of the indoor heat exchanger; Detecting a second slope indicating an amount of increase per unit time of the temperature of the heat storage material stored during the heat storage heating operation, and comparing the second slope with the first slope; controlling an opening degree of the first expansion valve based on a result of the comparison; A control method for a refrigeration cycle device comprising:

6. The outdoor heat exchanger includes an outdoor air temperature sensor for detecting an outdoor air temperature, 6. The method for controlling a refrigeration cycle apparatus according to claim 5, wherein in the step of setting the first gradient, the first gradient is set in accordance with the outside air temperature detected by the outside air temperature sensor.

7. one of the plurality of expansion valves is a second expansion valve provided downstream of the heat storage heat exchanger functioning as the condenser; 7. The method for controlling a refrigeration cycle apparatus according to claim 5, further comprising a step of controlling the opening degree of the second expansion valve to a predetermined opening degree during the heat storage heating operation.

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