Air conditioner

Abstract

To suppress reduction in comfort of a user involved in stop of a heating operation during a defrosting operation even in a case where a water circuit for using water as a secondary coolant is provided on a secondary side of a coolant circuit.SOLUTION: An air conditioner comprises: a compressor 11; a primary indoor apparatus 2; a relay unit 3 which is connected in parallel with the primary indoor apparatus 2; a primary coolant circuit C1 in which pressure reduction mechanisms 22 and 34 respectively included in the primary indoor apparatus 2 and the relay unit 3 are connected by coolant piping and a primary coolant is circulated; a secondary indoor apparatus 4 which is connected to the relay unit 3; a secondary coolant circuit C2 in which the secondary indoor apparatus 4 and a circulation pump 31 are connected by the coolant piping and a secondary coolant is circulated; and a control device 5 which controls the compressor 11 and the pressure reduction mechanisms 22 and 34. In a case where the primary indoor apparatus 2 and the relay unit 3 are performing a heating operation, before it is determined that a frosting determination condition is satisfied and a defrosting operation is started, the control device 5 implements a preheat operation in which a rotation speed of the compressor 11 rises and the heating operation of the relay unit 3 is prioritized over the heating operation of the primary indoor apparatus 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an air conditioner. [Background technology]

[0002] Generally, when an air conditioner is in heating operation, the indoor heat exchanger functions as a condenser, and the outdoor heat exchanger functions as an evaporator. In this case, a refrigerant that is lower in temperature than the outdoor air temperature flows through the outdoor heat exchanger. Therefore, for example, when the outdoor air temperature is below freezing, if the refrigerant temperature falls below the dew point of the outdoor air, frost will form on the outdoor heat exchanger, making it difficult to exchange heat with the outdoor air. Therefore, when the air conditioner is in heating operation, a defrosting operation is periodically performed to remove frost from the outdoor heat exchanger.

[0003] Such a defrosting operation is necessary for operating an air conditioner, and is typically performed by interrupting heating operation. Specifically, when starting a defrosting operation, the refrigerant circuit is switched so that refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger. That is, defrosting is performed by making the indoor heat exchanger function as an evaporator and the outdoor heat exchanger function as a condenser. During the defrosting operation, the high-temperature refrigerant supplied to the outdoor heat exchanger for defrosting melts the frost, lowers its temperature, and then passes through an expansion valve where it is decompressed to a low temperature, and the low-temperature refrigerant flows into the indoor heat exchanger. By stopping the indoor unit fan during the defrosting operation, heat exchange in the indoor heat exchanger is suppressed, and cool air is not blown out to the user.

[0004] However, when such a defrosting operation is performed, the room temperature gradually drops because the heating operation is stopped during the defrosting operation, which reduces user comfort. Therefore, for example, an operation to raise the room temperature in advance (hereinafter, such an operation will be referred to as "preheating operation") is performed, as in the air conditioning system shown in Patent Document 1 below. It is believed that performing the preheating operation before the defrosting operation can prevent a decrease in user comfort. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-075471 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when performing preheating operation between heating operation and defrosting operation, for example, there may be a large amount of frost already formed on the outdoor unit, or the compressor may be operating in heating operation at a speed close to its maximum speed.

[0007] In such a case, even if the preheating operation is performed, there is a possibility that the heating capacity required to raise the room temperature may not be secured. As a result, the room temperature may not be raised sufficiently before the defrosting operation, which may make it difficult to maintain user comfort.

[0008] Some refrigeration cycle devices include a refrigerant circuit on the primary side that uses a primary refrigerant such as an HFC refrigerant or a carbon dioxide refrigerant, a water circuit on the secondary side that uses water as a secondary refrigerant, and an intermediate heat exchanger that exchanges heat between the primary refrigerant and the secondary refrigerant. In this refrigeration cycle device, for example, the primary refrigerant heats water flowing through the water circuit, and the heated water heats a living space. In such a refrigeration cycle device, examples of devices that heat a living space include floor heating and radiators. In such devices, during the defrosting operation described above, the primary refrigerant absorbs heat from the water in the intermediate heat exchanger, thereby cooling the water. Therefore, it is desirable to continue circulating water in the water circuit during the defrosting operation to prevent the water from freezing due to excessive cooling in the intermediate heat exchanger and to ensure defrosting capacity by the primary refrigerant absorbing heat from the water. In such cases, the temperature of the water flowing through the water circuit decreases during the defrosting operation, and low-temperature water is sent to the living space.

[0009] In other words, in such a refrigeration cycle apparatus, the heating operation is stopped during the defrosting operation, and the defrosting operation also reduces the temperature of the water flowing in the water circuit, further reducing the indoor temperature. Furthermore, the drop in the temperature of the water flowing in the water circuit also reduces the sense of warmth felt by the user due to heat conduction and heat radiation from the water. Therefore, in such a refrigeration cycle apparatus, the user's comfort is significantly reduced.

[0010] The present invention is intended to solve the above-mentioned problems, and aims to provide an air conditioner that can suppress the decrease in user comfort that occurs when heating operation is stopped during defrosting operation, even if, for example, a water circuit using water as a secondary refrigerant is provided on the secondary side of the refrigerant circuit. [Means for solving the problem]

[0011] An air conditioner according to one aspect of the present invention comprises an outdoor unit equipped with a compressor, at least one primary indoor unit, at least one relay unit connected in parallel to the primary indoor unit, a primary refrigerant circuit in which the primary indoor unit and the pressure reduction mechanisms provided in each of the relay units are connected by refrigerant piping and in which the primary refrigerant circulates, at least one secondary indoor unit connected to the relay unit, a secondary refrigerant circuit in which the secondary indoor unit and a circulation pump are connected by refrigerant piping and in which water as a secondary refrigerant circulates by the operation of the circulation pump, and a control device that controls the compressor and the pressure reduction mechanism.When the control device determines that the frost formation determination conditions are met while the primary indoor unit and the relay unit are performing heating operation, the control device increases the rotation speed of the compressor and performs a preheat operation that prioritizes the heating operation of the relay unit over the heating operation of the primary indoor unit before starting a defrosting operation. [Effects of the Invention]

[0012] According to the present invention, even if a water circuit using water as a secondary refrigerant is provided on the secondary side of the refrigerant circuit, it is possible to suppress the decrease in user comfort that occurs when heating operation is stopped during defrosting operation. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing an internal configuration of a control device according to an embodiment of the present invention; [Figure 3] 4 is a flowchart showing the flow of control of a preheat operation in the air conditioner according to the embodiment of the present invention. [Figure 4] 1 is a flowchart showing the flow of control of preheating operation in an air conditioner according to an embodiment of the present invention, and is a flowchart showing the flow of processing when multiple types of secondary indoor units are connected to a secondary refrigerant circuit. [Figure 5] 4 is a flowchart showing a flow of control executed before a preheating operation in the air conditioner according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The structure of an air conditioner A 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 air conditioner A according to the embodiment of the present invention. The air conditioner A comprises an outdoor unit 1, at least one primary indoor unit 2, and at least one relay unit 3 connected in parallel to the primary indoor unit 2. The air conditioner A also comprises a primary refrigerant circuit C1 in which the outdoor unit 1, the primary indoor unit 2, and the relay unit 3 are connected by refrigerant piping and in which the primary refrigerant circulates. The air conditioner A also comprises a compressor 11 and a control device 5 that controls pressure reduction mechanisms 22 and 34.

[0015] The outdoor unit 1 includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, and an outdoor unit pressure reduction mechanism 14, each of which is connected to a primary refrigerant circuit C1. The outdoor unit pressure reduction mechanism 14 adjusts the overall flow rate of the primary refrigerant flowing through the primary refrigerant circuit C1, and is provided between the outdoor heat exchanger 13 and a primary indoor unit pressure reduction mechanism 22, described below, provided in, for example, the primary indoor unit 2. Note that other devices normally provided in the outdoor unit 1, such as an outdoor fan, are not shown in FIG. 1.

[0016] At least one primary indoor unit 2 is connected outside the outdoor unit 1 between the four-way valve 12 and the outdoor unit pressure reducing mechanism 14. In the case of the air conditioner A in the embodiment of the present invention, a plurality of primary indoor units 2 are connected in parallel, that is, in Fig. 1, two primary indoor units 2A, 2B. Note that, hereinafter, when these two primary indoor units 2A, 2B are described together, they will be referred to as the "primary indoor unit 2" as described above.

[0017] Each of these primary indoor units 2A, 2B includes a primary indoor unit heat exchanger 21 and a primary indoor unit pressure reduction mechanism 22, which are connected to the primary refrigerant circuit C1. Here, the primary indoor unit pressure reduction mechanism 22 is, for example, an expansion valve.

[0018] Furthermore, the primary indoor unit 2 is provided with a primary refrigerant temperature sensor 23 that measures the temperature of the primary refrigerant flowing out from the primary indoor unit heat exchanger 21 of the primary indoor unit 2 during heating operation. The primary refrigerant temperature sensor 23 is used to detect the degree of subcooling of the primary refrigerant at the outlet of the primary indoor unit heat exchanger 21 when the primary indoor unit pressure reducing mechanism 22, which will be described later, is controlled by feedback control. Other devices that are normally provided in the primary indoor unit 2, such as an indoor fan, are not shown in FIG. 1.

[0019] For example, when air conditioner A is operating in heating mode, the primary refrigerant circulates through the primary refrigerant circuit C1 in the following order: the above-mentioned compressor 11 provided in the outdoor unit 1, the four-way valve 12, the primary indoor unit heat exchanger 21 provided in the primary indoor unit 2, the primary indoor unit pressure reduction mechanism 22, the outdoor unit pressure reduction mechanism 14, the outdoor heat exchanger 13, the four-way valve 12, and the compressor 11.

[0020] During heating operation, the primary refrigerant compressed by the outdoor unit compressor 11 into a high-temperature, high-pressure gas phase state is supplied to the primary indoor unit heat exchanger 21. The high-temperature, high-pressure gas phase primary refrigerant flowing through the primary indoor unit heat exchanger 21 exchanges heat with indoor air taken in by an indoor fan (not shown) of the primary indoor unit 2, thereby releasing heat and condensing to a liquid phase. The air that has exchanged heat with the high-temperature, high-pressure primary refrigerant passing through the primary indoor unit heat exchanger 21 is warmed and supplied indoors.

[0021] The liquid-phase primary refrigerant that has passed through the primary indoor unit heat exchanger 21 is reduced in pressure as it passes through the primary indoor unit pressure reduction mechanism 22 and flows into the outdoor unit pressure reduction mechanism 14. The primary refrigerant that has passed through the outdoor unit pressure reduction mechanism 14 is further reduced in pressure as it becomes a low-temperature gas-liquid two-phase refrigerant and flows into the outdoor heat exchanger 13. The low-temperature primary refrigerant flowing through the outdoor heat exchanger 13 absorbs heat and evaporates into a gas phase by exchanging heat with outside air taken in by an outdoor fan (not shown). The gas-phase primary refrigerant that has passed through the outdoor heat exchanger 13 returns to the compressor 11 and is compressed to a high-temperature, high-pressure state.

[0022] The air conditioner A in the embodiment of the present invention further includes at least one relay unit 3 connected in parallel to the primary indoor unit 2. The relay unit 3 includes an intermediate heat exchanger 32, which thermally connects (relays) a primary refrigerant circuit C1 through which the primary refrigerant circulates and a secondary refrigerant circuit C2 through which a secondary refrigerant, described below, circulates.

[0023] In the air conditioner A according to the embodiment of the present invention, two relay units 3A and 3B are connected as the relay unit 3, as shown in the circuit diagram of Fig. 1. These two relay units 3A and 3B are both connected in parallel with the primary indoor unit 2. In the following description, when these two relay units 3A and 3B are described together, they will be referred to as "relay unit 3" as described above.

[0024] In this way, in the air conditioner A according to the embodiment of the present invention, the primary refrigerant circuit C1 is connected to a plurality of primary indoor units 2 and a plurality of relay units 3. As described above, in the circuit diagram shown in Fig. 1, two units are connected in each case, but the number of units can be any number.

[0025] A secondary refrigerant circuit C2 through which a secondary refrigerant circulates is connected to each of the relay units 3. A circulation pump 31 for circulating the secondary refrigerant, an intermediate heat exchanger 32 for exchanging heat between the secondary refrigerant and the primary refrigerant, and at least one secondary indoor unit 4 are connected to the secondary refrigerant circuit C2.

[0026] The circulation pump 31 discharges the secondary refrigerant to circulate the secondary refrigerant within the secondary refrigerant circuit C2. A fluid is used as the secondary refrigerant, and in this example, the secondary refrigerant is a fluid such as water or antifreeze. Note that, in the embodiments of the present invention, "water" also includes antifreeze and other fluids. Meanwhile, the primary refrigerant circulating through the primary refrigerant circuit C1 is, for example, R32 or other refrigerant.

[0027] The intermediate heat exchanger 32 exchanges heat between the primary refrigerant circulating in the primary refrigerant circuit C1 and the secondary refrigerant circulating in the secondary refrigerant circuit C2. The secondary refrigerant flowing out of the intermediate heat exchanger 32 flows into the secondary indoor unit 4, and exchanges heat with the indoor air in the secondary indoor unit heat exchanger 41.

[0028] Here, the secondary indoor unit 4 is, for example, a fan coil unit that uses water as a refrigerant to perform heating and cooling. In addition, examples of devices that heat living spaces include floor heating and radiators.

[0029] In the secondary indoor unit 4 shown in FIG. 1, only the secondary indoor unit heat exchanger 41 is depicted, and other devices provided in the secondary indoor unit 4, such as an indoor fan, are not depicted.

[0030] As described above, at least one secondary indoor unit 4 is connected to one relay unit 3. Therefore, two secondary indoor units 4A, 4B are shown in the air conditioner A shown in Fig. 1. However, when the secondary indoor units 4A, 4B are not mentioned individually, they will be collectively referred to as "secondary indoor units 4."

[0031] The relay unit 3 is also provided with a secondary refrigerant temperature sensor 33 for detecting the temperature of the secondary refrigerant that has undergone heat exchange in the intermediate heat exchanger 32. Furthermore, a relay unit pressure reducing mechanism 34 is provided on the primary refrigerant circuit C1 side of the relay unit 3, on the side connected to the outdoor heat exchanger 13 of the outdoor unit 1. Here, the relay unit pressure reducing mechanism 34 is, for example, an expansion valve.

[0032] Furthermore, the relay unit 3 is provided with a primary refrigerant temperature sensor 35 that measures the temperature of the primary refrigerant flowing out from the intermediate heat exchanger 32 during heating operation. The primary refrigerant temperature sensor 35 is used to detect the degree of subcooling of the primary refrigerant at the outlet of the intermediate heat exchanger 32 when a relay unit pressure reducing mechanism 34 (described later) is controlled by feedback control.

[0033] The function of such a relay unit 3 is as follows, taking the case where heating operation is performed in the air conditioner A as an example: The primary refrigerant circulates within the primary refrigerant circuit C1, passing through the above-mentioned compressor 11 provided in the outdoor unit 1, the four-way valve 12, the intermediate heat exchanger 32 provided in the relay unit 3, the relay unit pressure reduction mechanism 34, the outdoor unit pressure reduction mechanism 14, the outdoor heat exchanger 13, the four-way valve 12, and the compressor 11 in this order.

[0034] On the other hand, the secondary refrigerant circulates within the secondary refrigerant circuit C2 in the order of the circulation pump 31 provided inside the relay unit 3, the intermediate heat exchanger 32, the secondary indoor unit heat exchanger 41 of the secondary indoor unit 4, and the circulation pump 31.

[0035] During heating operation, the primary refrigerant compressed by the compressor 11 of the outdoor unit into a high-temperature, high-pressure gas phase state is supplied to the intermediate heat exchanger 32. The high-temperature, high-pressure gas phase primary refrigerant flowing through the intermediate heat exchanger 32 releases heat and condenses into a liquid phase by exchanging heat with a secondary refrigerant, for example, water, circulating in the secondary refrigerant circuit C2. The water that has exchanged heat with the high-temperature, high-pressure primary refrigerant passing through the intermediate heat exchanger 32 is warmed and flows into the secondary indoor unit 4.

[0036] In the secondary indoor unit heat exchanger 41 of the secondary indoor unit 4, the inflowing water (secondary refrigerant) dissipates heat by exchanging heat with indoor air drawn in by an indoor fan (not shown) of the secondary indoor unit 4. The air that has exchanged heat with the secondary refrigerant passing through the secondary indoor unit heat exchanger 41 is heated and supplied to the room. The secondary refrigerant that has exchanged heat flows out of the secondary indoor unit heat exchanger 41 and flows back into the circulation pump 31.

[0037] The liquid-phase primary refrigerant that has passed through the intermediate heat exchanger 32 is reduced in pressure as it passes through the relay unit pressure reduction mechanism 34 and flows into the outdoor unit pressure reduction mechanism 14. The primary refrigerant that has passed through the outdoor unit pressure reduction mechanism 14 is further reduced in pressure as it becomes a low-temperature gas-liquid two-phase refrigerant and flows into the outdoor heat exchanger 13. The low-temperature primary refrigerant flowing through the outdoor heat exchanger 13 absorbs heat and evaporates into a gas phase state as it exchanges heat with outside air taken in by an outdoor fan (not shown). The gas-phase primary refrigerant that has passed through the outdoor heat exchanger 13 returns to the compressor 11 and is compressed to a high-temperature, high-pressure state.

[0038] The control device 5 controls each component of the air conditioner A, such as the compressor 11, the primary indoor unit pressure reduction mechanism 22, and the relay unit pressure reduction mechanism 34. Although the control device 5 is depicted in Fig. 1 as being provided inside the air conditioner A, the control device 5 may be provided in the outdoor unit 1, the primary indoor unit 2, or the relay unit 3, for example, or may be provided separately in the outdoor unit 1, the primary indoor unit 2, and the relay unit 3.

[0039] 2 is a block diagram showing the internal configuration of the control device 5 according to the embodiment of the present invention. As shown in FIG. 2, the control device 5 includes a detection unit 51, a storage unit 52, a determination unit 53, and a pressure reduction mechanism control unit 54.

[0040] The detection unit 51 detects the outlet side refrigerant temperature of the primary indoor unit heat exchanger 21 measured by the primary refrigerant temperature sensor 23 and the outlet side refrigerant temperature of the intermediate heat exchanger 32 measured by the primary refrigerant temperature sensor 35.

[0041] The storage unit 52 stores various detection values ​​detected by the detection unit 51 as appropriate. The storage unit 52 also stores, for example, frost formation determination conditions used to determine whether or not to perform a preheating operation during a transition from a heating operation to a defrosting operation, which will be described later. The storage unit 52 may also store a value of the degree of subcooling that serves as a target value when feedback control is executed during the heating operation.

[0042] Furthermore, when feedforward control is performed instead of feedback control during heating operation of the air conditioner A, a predetermined increase rate for the primary indoor unit pressure reduction mechanism 22 and a predetermined increase rate for the relay unit pressure reduction mechanism 34 are also stored, which are used when controlling the opening degrees of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34. The predetermined increase rates will be described later.

[0043] The determination unit 53 determines the operating state of the air conditioner A when the control device 5 executes control over the air conditioner A. Specifically, for example, it determines the operating state, such as the start or stop of heating operation, of each primary indoor unit 2 and each relay unit 3. It also determines whether to perform heating operation on the air conditioner A or whether to transition to defrosting operation, or, if preheating operation is to be performed during the transition from heating operation to defrosting operation, how to perform the preheating operation.

[0044] The pressure reducing mechanism control unit 54 controls the opening degrees of the primary indoor unit pressure reducing mechanism 22 and the relay unit pressure reducing mechanism 34 to predetermined opening degrees based on the determination of the determination unit 53. In the following description, the fact that the secondary indoor unit 4 is performing heating operation and the circulation pump 31 is being driven will be appropriately expressed as "the relay unit 3 is performing heating operation."

[0045] The control of air conditioner A by control device 5 executed in the embodiment of the present invention is control related to preheating operation that is performed between heating operation and defrosting operation. That is, when air conditioner A is performing heating operation and determination unit 53 determines that it is necessary to transition to defrosting operation, the operating mode transitions from heating operation to preheating operation, and then transitions to defrosting operation after the preheating operation is completed.

[0046] Therefore, the determination unit 53 first determines whether or not the frost formation determination condition is satisfied during heating operation. Here, the frost formation determination condition is a condition used when determining whether or not a transition to defrosting operation is necessary, and is a condition for determining that frost formation is progressing.

[0047] Specifically, the conditions include, for example, that the evaporation temperature in the outdoor heat exchanger 13 is below a threshold value and the rate of decrease of the evaporation temperature is above a threshold value, that the value obtained by subtracting the evaporation temperature from the outdoor air temperature is above a threshold value, or that the outdoor air temperature is below a threshold value and that heating operation continues continuously for a predetermined period of time or more.

[0048] Any of these conditions may be used, or they may be combined as appropriate. In addition, multiple thresholds are used here, but these are set in advance and stored in the storage unit 52, for example.

[0049] If the determining unit 53 determines that the frost formation determination conditions are not satisfied, there is no need to perform the defrosting operation, and the heating operation continues.

[0050] The determination of whether the frost formation determination condition is satisfied by the determination unit 53 is performed at any time during heating operation, and may be performed at preset time intervals, or may be performed when the detection unit 51 detects information about the outside air temperature detected by an outside air temperature sensor (not shown in Fig. 1).

[0051] On the other hand, if the determination unit 53 determines that the frost formation determination condition is met, the operation proceeds to preheating operation. Note that when the preheating operation is performed, the operation proceeds to defrosting operation and the heating operation continues.

[0052] As described above, the preheating operation is an operation for raising the room temperature before starting the defrosting operation. By performing the preheating operation, it is possible to reduce the decrease in user comfort even if the heating operation is stopped during the defrosting operation.

[0053] Here, the air conditioner A shown in the embodiment of the present invention employs a configuration in which, in addition to a primary indoor unit 2, a secondary indoor unit 4 is connected via a relay unit 3. The secondary indoor unit 4 is connected to a secondary refrigerant circuit C2 that uses water as the secondary refrigerant.

[0054] When water is used as the refrigerant circulating through the secondary refrigerant circuit C2 in this way, the heating operation is stopped during defrosting operation, and therefore the primary refrigerant absorbs heat from the water in the intermediate heat exchanger 32, and the water releases heat and is cooled. Especially when water, which serves as the secondary refrigerant, needs to be circulated through the secondary refrigerant circuit C2, the temperature of the water flowing through the secondary refrigerant circuit C2 gradually drops during defrosting operation, causing low-temperature water to be sent to the living space. As a result, user comfort cannot be maintained.

[0055] Therefore, in the air conditioner A according to the embodiment of the present invention, when preheating operation is performed, the rotation speed of the compressor 11 is increased to increase the heating capacity, and control is performed to prioritize the heating operation of the relay unit 3 over the heating operation of the primary indoor unit 2.

[0056] By performing such control, the temperature of the water flowing through the secondary refrigerant circuit C2 can be kept high during defrosting operation, thereby preventing a decrease in user comfort. Furthermore, since the water temperature remains high, the decrease in water temperature can be minimized even when heating operation is resumed after defrosting operation, making it possible to quickly raise the water temperature after heating operation is resumed. This is effective in a refrigerant circuit that uses water, which is more difficult to heat than air, as a refrigerant. Therefore, this also helps prevent a decrease in user comfort.

[0057] Therefore, in order to prioritize heating operation on the secondary indoor unit 4 side over the primary indoor unit 2 side, the control device 5 controls the rate of increase in heating capacity during preheat operation so that it is greater in the relay unit 3 than in the primary indoor unit 2, based on the heating capacity during heating operation before the preheat operation is performed.

[0058] Here, a difference in heating capacity occurs before and after the preheat operation when the preheat operation is performed. Therefore, in an embodiment of the present invention, the difference in heating capacity before and after the preheat operation is expressed as the rate of increase, and the rate of increase in heating capacity is controlled to be greater in the relay unit 3 than in the primary indoor unit 2.

[0059] More specifically, the pressure reduction mechanism control unit 54 controls the opening degrees of the respective pressure reduction mechanisms, that is, the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34, so that the rate of increase in the opening degrees of the pressure reduction mechanisms is greater in the relay unit 3 than in the primary indoor unit 2.

[0060] Here, the "opening degree of the pressure reduction mechanism" represents, for example, the ratio of the Cv value in the current adjustment state to the Cv value (a coefficient that indicates the ease of fluid flow) when the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 are fully open. Generally, the primary indoor unit pressure reduction mechanism 22 equipped in the primary indoor unit 2 and the relay unit pressure reduction mechanism 34 equipped in the relay unit 3 both employ pressure reduction mechanisms with diameters that correspond to the rated capacities of the primary indoor unit 2 and the relay unit 3, respectively.

[0061] Therefore, the Cv value when the pressure-reducing mechanism is opened varies depending on the diameter of the installed pressure-reducing mechanism. Therefore, if the Cv value is used to "adjust the opening of the pressure-reducing mechanism so that the relay unit 3's opening is larger than that of the primary indoor unit 2," it may not always be possible to control the rate of increase in the heating capacity of the relay unit 3 to be greater than that of the primary indoor unit 2. For example, if the relay unit 3 has twice the capacity of the primary indoor unit 2 and the diameter of the relay unit pressure-reducing mechanism 34 is sufficiently larger than the diameter of the primary indoor unit pressure-reducing mechanism 22, simply controlling the Cv value of the relay unit pressure-reducing mechanism 34 to be slightly larger than the Cv value of the primary indoor unit pressure-reducing mechanism 22 will result in a larger refrigerant flow rate relative to the rated capacity of the primary indoor unit 2, and it cannot be said that the heating capacity of the relay unit 3 is prioritized. Therefore, in an embodiment of the present invention, when performing preheating operation, control is performed using the "rate of increase in the opening of the pressure-reducing mechanism" to more reliably prioritize the heating capacity of the relay unit 3 over that of the primary indoor unit 2.

[0062] Also, the "opening degree" has been described as the ratio of the Cv value in the current adjustment state to the Cv value when the primary indoor unit pressure-reducing mechanism 22 and the relay unit pressure-reducing mechanism 34 are fully open. However, the present invention is not limited to this, and any parameter that changes in correlation with the ratio of the Cv values ​​can be substituted for the "opening degree." For example, the ratio of the flow rate per unit time when a single-phase fluid flows at a predetermined inlet / outlet pressure can be substituted for the opening degree, or, if the primary indoor unit pressure-reducing mechanism 22 and the relay unit pressure-reducing mechanism 34 are electronic expansion valves driven by a pulse motor, the number of pulses provided to the pulse motor can be substituted for the opening degree.

[0063] In this way, as long as each pressure reducing mechanism is controlled so that the rate of increase in the opening degree of the pressure reducing mechanism is greater in the relay unit 3 than in the primary indoor unit 2, the absolute amount of primary refrigerant flowing may be greater or less in the primary indoor unit 2 than in the relay unit 3.

[0064] When the preheat operation starts, the pressure reduction mechanism control unit 54 first uses feedforward control to increase the opening degree of each of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 at a predetermined increase rate in accordance with the increase in the rotation speed of the compressor 11.

[0065] Here, the "predetermined increase rate" is a value that is determined in advance by experimentation as a value that prevents the refrigerant drawn into the compressor 11 from becoming overly wet or overheated, and is stored in the memory unit 52. The predetermined increase rate is set to be larger for the relay unit pressure reduction mechanism 34 than for the primary indoor unit pressure reduction mechanism 22. For example, when the preheat operation is started, if the rotation speed of the compressor 11 increases by 10%, the predetermined increase rate is set so that the opening degree of the primary indoor unit pressure reduction mechanism 22 is increased by 5%, while the opening degree of the relay unit pressure reduction mechanism 34 is increased by 7%.

[0066] That is, regardless of whether feedforward control is in effect or not, when the rotation speed of the compressor 11 increases, the opening degrees of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 are also controlled to match the rotation speed of the compressor 11. Therefore, in this feedforward control, a difference is set between the primary indoor unit 2 and the relay unit 3 in the opening rate of each pressure reduction mechanism that matches the rotation speed of the compressor 11.

[0067] In this way, a predetermined increase rate is set for each of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34, and the increase rate is set to be greater for the relay unit pressure reduction mechanism 34 than for the primary indoor unit pressure reduction mechanism 22. This makes it possible to increase the heating capacity by prioritizing the secondary indoor unit 4 side over the primary indoor unit 2 side.

[0068] On the other hand, when the feedforward control ends, the operation switches to preheating operation using feedback control. That is, the pressure reducing mechanism control section 54 controls the opening degrees of the primary indoor unit pressure reducing mechanism 22 and the relay unit pressure reducing mechanism 34 in accordance with the target values ​​set for the primary indoor unit 2 and the relay unit 3, respectively.

[0069] When feedback control is performed during heating operation, the following control is performed on the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34. That is, so-called target subcooling control is performed to set the degree of subcooling at the outlet of the primary indoor unit heat exchanger 21 and the degree of subcooling at the outlet of the intermediate heat exchanger 32 to predetermined target values ​​that are set for each.

[0070] Therefore, when preheating operation is performed by feedback control, for example, the target subcool value for the relay unit 3 is set to be smaller than the target subcool value for the primary indoor unit 2. The target subcool values ​​set for each of the primary indoor unit 2 and the relay unit 3 correspond to the target values ​​described above. The pressure reduction mechanism control unit 54 then controls the opening of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 so that the target subcool values ​​set for each are achieved. As a result, the opening of the relay unit pressure reduction mechanism 34 is controlled to be large so that the degree of subcooling at the outlet of the intermediate heat exchanger 32 approaches the small target subcool value, and the rate of increase in the opening increases.

[0071] That is, as described above, first, preheating operation is performed by feedforward control, and the pressure reducing mechanism control section 54 controls each pressure reducing mechanism so that the rate of increase in the opening degree of the pressure reducing mechanism is greater in the relay unit 3 than in the primary indoor unit 2. After that, feedback control is executed, which is essentially a control that adjusts the values ​​so that they converge to the final set value.

[0072] For this reason, even though the pressure reducing mechanism control section 54 has performed feedforward control to cause more refrigerant to flow to the relay unit 3 than to the primary indoor unit 2, so to speak, it is possible that the bias purposely placed on the relay unit 3 side may be reduced or even eliminated by performing feedback control. This makes it impossible to ensure the effectiveness of the control of the preheat operation in the embodiment of the present invention.

[0073] Therefore, for example, the target subcool value for the relay unit 3 is set to be smaller than the target subcool value for the primary indoor unit 2, and the pressure reduction mechanism control section 54 controls the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 in accordance with this setting. By performing control in this manner, it is possible to maximize the effect of the combined feedforward control and feedback control during preheat operation.

[0074] As described above, feedback control is performed so that the target subcooling value set for each of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 is reached. Therefore, both cases where the opening degree increases and cases where the opening degree decreases are possible. However, no matter how the opening degree of the pressure reduction mechanism changes, the relay unit 3 is still controlled so that the rate of increase in heating capacity is greater than that of the primary indoor unit 2.

[0075] Therefore, in controlling the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34, the pressure reduction mechanism control unit 54 controls the opening degree of the latter so that the "increase rate" is larger and the "decrease rate" is smaller compared to the opening degree of the former.

[0076] The degree of subcooling is determined based on information transmitted from sensors that detect the degree of subcooling of the primary refrigerant at the outlets of the primary indoor unit heat exchanger 21 and the intermediate heat exchanger 32. Specifically, the degree of subcooling is determined from the difference between the condensing temperature and the condenser outlet temperature, and therefore the degree of subcooling of the primary refrigerant at the outlet of the primary indoor unit heat exchanger 21 is calculated by subtracting the detection value of the primary refrigerant temperature sensor 23 from the detection value of a condensing temperature sensor (not shown) provided in the primary indoor unit 2. Similarly, the degree of subcooling of the primary refrigerant at the outlet of the intermediate heat exchanger 32 is calculated by subtracting the detection value of the primary refrigerant temperature sensor 35 from the detection value of a condensing temperature sensor (not shown) provided in the relay unit 3.

[0077] Although the preheating operation control described here is a combination of feedforward control and feedback control, it is not necessary to combine these controls, and the preheating operation may be performed using only one of the controls.

[0078] So far, we have explained the control of the preheat operation in which the heating capacity is increased by increasing the rotation speed of the compressor 11, and the heating capacity is increased by giving priority to the secondary indoor unit 4 over the primary indoor unit 2. In other words, we have explained how the rate of increase in heating capacity when the preheat operation is performed is controlled between the primary indoor unit 2 and the relay unit 3. Therefore, we have not mentioned the ratio at which the primary refrigerant is distributed among multiple relay units 3, which results in a larger rate of increase in heating capacity.

[0079] Possible types of secondary indoor units 4 connected to the relay unit 3 include, for example, forced convection type secondary indoor units and natural convection type secondary indoor units. For example, the fan coil unit described above supplies warm air into the room by forced convection via a fan, and therefore falls under the category of forced convection type secondary indoor units.

[0080] On the other hand, even if the secondary indoor unit 4 is also a secondary indoor unit of the natural convection type, for example, the above-mentioned floor heating and radiator do not supply warm air into the room using a fan, but heat the room by supplying heat radiated by the floor heating or the like into the room by natural convection. Therefore, these secondary indoor units 4 are natural convection type secondary indoor units.

[0081] The type of secondary indoor unit 4 connected to the relay unit 3 in the embodiment of the present invention is not particularly limited, and either the forced convection type secondary indoor unit or the natural convection type secondary indoor unit described above may be connected. However, from the perspective of avoiding a decrease in user comfort when heating operation is stopped and defrosting operation is switched to, it is thought that even if the secondary indoor unit 4 is the same, a forced convection type secondary indoor unit can avoid a decrease in user comfort to some extent by at least stopping the driving of the fan.

[0082] That is, even if the temperature of the water, which is the secondary refrigerant, drops during defrosting operation, a forced convection type secondary indoor unit 4 will stop driving the fan and will not blow cold air to the user. In contrast, in the case of a natural convection type secondary indoor unit, a drop in the water temperature reduces the heat conduction through the floor and the feeling of warmth due to heat radiation, and defrosting operation directly leads to a decrease in user comfort.

[0083] In light of the above, if the rate of increase in heating capacity that is disproportionately allocated to the relay unit 3 rather than the primary indoor unit 2 is allocated equally to the secondary indoor units 4 connected to the relay unit 3, it could result in a decrease in user comfort in a room where a natural convection type secondary indoor unit is installed compared to a room where a forced convection type secondary indoor unit is installed.

[0084] Therefore, when multiple types of secondary indoor units 4 are connected to the relay unit 3 as the secondary indoor units 4, the control described below is performed. The control flow described below is performed as part of the control of the preheat operation described above, and more specifically, it is performed after the rate of increase in heating capacity for the primary indoor units 2 and the relay unit 3 has been set.

[0085] Furthermore, when the following control is performed, it is assumed that the types of secondary indoor units 4 connected to the relay unit 3 include forced convection type secondary indoor units and natural convection type secondary indoor units. Therefore, if all secondary indoor units 4 are of the same type, the control described below will not be executed.

[0086] First, the determination unit 53 calculates the total capacity (rated heating capacity) of all secondary indoor units 4 connected to the secondary refrigerant circuit C2 of the relay unit 3. In the air conditioner A in the embodiment of the present invention, a plurality of relay units 3 is provided, and the total capacity of the secondary indoor units 4 connected to each of these plurality of relay units 3 is calculated for each of these relay units 3.

[0087] Next, the determination unit 53 calculates the total capacity of the natural convection type secondary indoor units connected to the relay unit 3. This total capacity of the natural convection type secondary indoor units is also calculated for each relay unit 3. The determination unit 53 then calculates the ratio of the total capacity of the natural convection type secondary indoor units 4 to the total capacity of the secondary indoor units 4 for each relay unit 3. This determines the proportion of natural convection type secondary indoor units connected to each of multiple relay units 3.

[0088] The determination unit 53 then confirms which of the relay units 3 has the larger ratio. Then, the determination unit 53 instructs the pressure reduction mechanism control unit 54 to control the relay unit pressure reduction mechanism 34 so that the rate of increase in heating capacity of the relay unit 3 with the larger calculated ratio becomes. The pressure reduction mechanism control unit 54 controls each relay unit pressure reduction mechanism 34 based on the instruction from the determination unit 53.

[0089] That is, even among the relay units 3 that are controlled so that the rate of increase in heating capacity is greater than that of the primary indoor units 2, the relay units 3 that have a higher ratio of the capacity of natural convection type secondary indoor units are controlled so that the rate of increase in heating capacity is greater. By performing such control, it is possible to avoid a decrease in user comfort in any of the multiple relay units 3.

[0090] As explained above, the preheating operation is performed during the heating operation and before the defrosting operation is started. Therefore, when the preheating operation is performed, the heating operation is also performed at the same time.

[0091] The preheating operation is an operation mode performed to suppress a decrease in user comfort due to the heating operation being stopped during the defrosting operation. Therefore, the preheating operation is performed while the heating operation is continued, and is not performed at the expense of the heating capacity of the heating operation.

[0092] Therefore, if preheating operation must be performed when there is no room for heating capacity, there is little spare capacity in the compressor 11. Therefore, when increasing the heating capacity by increasing the rotation speed of the compressor 11 as described above, it is particularly effective to control the increase in heating capacity by giving priority to the secondary indoor unit 4 side over the primary indoor unit 2 side.

[0093] On the other hand, when the heating operation in the primary indoor unit 2 or the secondary indoor unit 4 is in a low load operation state, for example, and the compressor 11 has sufficient spare capacity, and it is possible to switch from this state to preheat operation, the preheat operation is performed without prioritizing the heating operation of either the primary indoor unit 2 or the secondary indoor unit 4.

[0094] The above control will be described in detail below. Note that the control described below is executed before the control of the preheating operation described above, and more specifically, after the determination unit 53 determines whether or not the frost formation determination condition is satisfied and determines that the preheating operation should be performed.

[0095] First, the determination unit 53 calculates the heating capacity (required output) required for preheat operation for each of all primary indoor units 2 that are performing heating operation. The determination unit 53 calculates, as the required output, the heating capacity that is required when the set temperature, which is the target value for the room temperature of the room in which the primary indoor unit 2 is installed, is raised by a predetermined temperature (for example, 2°C). The determination unit 53 calculates the required output by referring to a table pre-stored in the memory unit 52, depending on the difference between the set temperature raised by the predetermined temperature and the room temperature of the room in which the primary indoor unit 2 is installed.

[0096] Furthermore, the determination unit 53 calculates the heating capacity (required output) required for preheat operation for each of all relay units 3 in heating operation. The determination unit 53 calculates the heating capacity required when the set temperature, which is the target value for the temperature of the water flowing through the relay unit 3, is raised by a predetermined temperature (for example, 2°C), as the required output. The determination unit 53 calculates the required output by referring to a table stored in advance in the storage unit 52, depending on the difference between the set temperature raised by the predetermined temperature and the temperature of the water flowing through the relay unit 3.

[0097] That is, the determination unit 53 calculates the required heating capacity output in preheating operation for each of all primary indoor units 2 in heating operation. In addition, the determination unit 53 also calculates the required heating capacity output in preheating operation for each of all relay units 3 in heating operation. Then, the determination unit 53 calculates the total amount (hereinafter referred to as "total required output") obtained by adding together the required heating capacity output on the primary indoor unit 2 side and the required heating capacity output on the relay unit 3 side.

[0098] The determination unit 53 also calculates the heating capacity (maximum output) that can be output in preheat operation as the air conditioner A. The determination unit 53 calculates the maximum heating capacity output by referring to a table stored in advance in the storage unit 52 according to the current environmental temperature (for example, the outside air temperature).

[0099] The judgment unit 53 compares the calculated total required output with the maximum output, and if it judges that the total required output is equal to or greater than the maximum output, as explained above, it performs preheating operation, prioritizing the heating operation of the relay unit 3 over the heating operation of the primary indoor unit 2.

[0100] On the other hand, if the determination unit 53 determines that the total required output is a value smaller than the maximum output, preheating operation is performed on the primary indoor unit 2 and the relay unit 3 with the heating capacity of the air conditioner A that matches the required output of each of the primary indoor unit 2 and the relay unit 3. Based on instructions from the determination unit 53, the pressure reduction mechanism control unit 54 controls the primary indoor unit pressure reduction mechanism 22 to perform preheating operation according to the required output of the primary indoor unit 2. The pressure reduction mechanism control unit 54 also controls the relay unit pressure reduction mechanism 34 to perform preheating operation according to the required output of the relay unit 3.

[0101] In the above description, the required output and maximum output are described as heating capacities, but the present invention is not limited to this. For example, the rotation speed of the compressor or a code obtained by interpreting the rotation speed of the compressor may be used as the required capacity or maximum output.

[0102] [Operation] Next, the flow of processing when a preheating operation is performed to avoid a decrease in user comfort during a defrosting operation will be described in order using Figures 3 to 5. First, the basic control flow will be described. Figure 3 is a flowchart showing the control flow of the preheating operation in an air conditioner A according to an embodiment of the present invention.

[0103] First, since the preheating operation requires that the heating operation is already in progress, the heating operation is started (ST1). When the heating operation is started, the determination unit 53 appropriately determines whether or not the frost formation determination condition is met (ST2).

[0104] If the judgment unit 53 judges that the frost formation judgment conditions are not met (NO in ST2), there will be no transition from heating operation to defrosting operation at the time of judgment, so the heating operation continues and the processing of ST2 is repeated until the frost formation judgment conditions are met.

[0105] On the other hand, if the determination unit 53 determines that the frost formation determination condition is met (YES in ST2), the preheating operation is started (ST3). In the preheating operation, the rate of increase of the heating capacity is controlled to be greater in the relay unit 3 than in the primary indoor unit 2.

[0106] In other words, the pressure reduction mechanism control unit 54 controls the opening degrees of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 so that the rate of increase in the opening degree of the pressure reduction mechanism is greater in the relay unit 3 than in the primary indoor unit 2.

[0107] Specifically, first, feedforward control is executed, and in accordance with the increase in the rotation speed of the compressor 11, the opening degrees of the primary indoor unit pressure reduction mechanism 22 and the relay unit pressure reduction mechanism 34 are controlled at predetermined increase rates set for the primary indoor unit 2 and the relay unit 3, respectively (ST4). The predetermined increase rate is set so that it is larger for the relay unit pressure reduction mechanism 34 than for the primary indoor unit pressure reduction mechanism 22.

[0108] Next, the openings of the primary indoor unit pressure reducing mechanism 22 and the relay unit pressure reducing mechanism 34 are controlled by feedback control in accordance with the target values ​​respectively set for the primary indoor unit 2 and the relay unit 3 (ST5). As described above, the target value here is, for example, a target subcool value, and the target subcool value for the relay unit 3 is set to be smaller than the target subcool value for the primary indoor unit 2. Note that the processing of step ST5 may be performed simultaneously with step ST4. That is, the processing of step ST5 may be started while the rotation speed of the compressor 11 is increasing.

[0109] While such a preheating operation is being performed, the determination unit 53 determines whether a completion condition for the preheating operation has been met, such as whether a preset room temperature has been reached (ST6). If the determination result shows that the completion condition has not yet been met (NO in ST6), the preheating operation continues, and the processing of step ST6 is repeated until the completion condition is met.

[0110] On the other hand, if the determination unit 53 determines that the completion condition is met (YES in ST6), the preheating operation and the heating operation are terminated (ST7). Then, the defrosting operation is started (ST8). When the defrosting operation is completed, the control related to the preheating operation is terminated.

[0111] Next, we will explain the control flow of the preheating operation when a forced convection type secondary indoor unit or a natural convection type secondary indoor unit is connected to the relay unit 3. Fig. 4 is a flowchart showing the control flow of the preheating operation in the air conditioner A according to the embodiment of the present invention, and is a flowchart showing the processing flow related to the control of the relay unit pressure reducing mechanism 34 when multiple types of secondary indoor units 4 are connected to the secondary refrigerant circuit C2.

[0112] The flowchart shown in Fig. 4 shows details of the processing related to the control of the relay unit pressure reduction mechanism 34 when the preheating operation is performed. Therefore, in terms of the flowchart shown in Fig. 3, when the preheating operation is started (ST3), steps ST4 to ST5 are executed in parallel.

[0113] The determination unit 53 first calculates the total capacity of all secondary indoor units 4 connected to the secondary refrigerant circuit C2 in the relay unit 3 (ST21). The determination unit 53 also calculates the total capacity of natural convection type secondary indoor units among the secondary indoor units 4 (ST22). Then, the determination unit 53 calculates the ratio of the total capacity of the natural convection type secondary indoor units to the total capacity of the secondary indoor units 4 (ST23).

[0114] As the ratio for each of the plurality of relay units 3 has been calculated as described above, it is next confirmed which relay unit 3 has the larger ratio (ST24). The determination unit 53 instructs the pressure reduction mechanism control unit 54 to control the pressure reduction mechanisms 34 of each relay unit so that the rate of increase in heating capacity increases for a relay unit 3 with a larger ratio. The pressure reduction mechanism control unit 54 controls the opening degree of each relay unit pressure reduction mechanism 34 based on the instruction from the determination unit 53 (ST25).

[0115] Next, a control flow will be described for the case where there is sufficient heating capacity remaining in the compressor 11. Fig. 5 is a flowchart showing the control flow for determining the content of the preheating operation to be performed before the preheating operation in the air conditioner A according to the embodiment of the present invention.

[0116] The control in the flowchart shown in Fig. 5 is executed after the determination unit 53 determines whether the frost formation determination conditions are met and determines to perform the preheating operation. Therefore, in terms of the flowchart shown in Fig. 3, the control is executed after the determination process (ST2) of whether the frost formation determination conditions are met is completed.

[0117] As described above, in this case, it is not necessary to control the rate of increase in heating capacity when preheating operation is performed so that the relay unit 3 is greater than the primary indoor unit 2, using the heating capacity during heating operation before preheating operation as a reference.

[0118] First, the determination unit 53 calculates the required output in preheating operation for each of all primary indoor units 2 that are performing heating operation. It also calculates the required output in preheating operation for each of all relay units 3 that are performing heating operation. Then, it calculates the total required output by adding the required output on the primary indoor unit 2 side and the required output on the relay unit 3 side (ST31).

[0119] Furthermore, the determination unit 53 calculates the maximum output that can be output by the air conditioner A in preheat operation (ST32). The determination unit 53 compares the calculated total required output with the maximum output (ST33), and determines whether the total required output is smaller than the maximum output (ST34).

[0120] If the judgment unit 53 judges that the total required output is equal to or greater than the maximum output (YES in ST34), as explained above, it decides to perform preheating operation, prioritizing the heating operation of the relay unit 3 over the heating operation of the primary indoor unit 2, and ends the control (ST35).

[0121] On the other hand, if the judgment unit 53 judges that the total required output is smaller than the maximum output (NO in ST34), it decides to perform preheating operation on the primary indoor unit 2 and the relay unit 3 with the heating capacity of the air conditioner A that matches the required output of each of the primary indoor unit 2 and the relay unit 3, and ends the control (ST36).

[0122] The process described using the flowchart shown in Fig. 5 is specifically connected between step ST2 and step ST3 in the flowchart shown in Fig. 3. Then, the above-described preheating operation is performed according to the mode of preheating operation determined in each case.

[0123] By performing the control described above, it is possible to provide an air conditioner that can suppress the decrease in user comfort that occurs when heating operation is stopped during defrosting operation, even if, for example, a water circuit using water as a secondary refrigerant is provided on the secondary side of the refrigerant circuit.

[0124] It should be noted that the present invention is not limited to the above-described embodiment, which is merely an example of the present invention. In the implementation stage, the components can be modified and embodied without departing from the spirit of the invention, and various changes and improvements can be made to the above-described embodiment. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiment.

[0125] For example, some components may be deleted from all of the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate, and such modified or improved forms may also be included in the present invention. Such embodiments and their modifications are included in the scope and spirit of the inventions, and are also included in the scope of the inventions and their equivalents as defined in the claims.

[0126] Note that, up to this point, an example has been described in which the opening degree of the pressure reducing mechanism before the preheating operation is used as a reference and the rate of increase in the opening degree of the pressure reducing mechanism when the preheating operation is performed is controlled to be greater in the relay unit than in the primary indoor unit. However, other methods can also be used as a method of controlling the rate of increase in the heating capacity when the preheating operation is performed is used as a reference and the heating capacity in the heating operation before the preheating operation is used as a reference and the rate of increase in the heating capacity of the relay unit when the preheating operation is performed is controlled to be greater than in the primary indoor unit.

[0127] In other words, rather than controlling the rate of increase in the opening of the pressure reducing mechanism, for example, if a fan is provided in each of the primary indoor unit and the secondary indoor unit, it is also possible to control the rate of increase in heating capacity when preheating operation is performed so that it is greater in the relay unit than in the primary indoor unit by increasing or decreasing the rotation speed of each fan.

[0128] The techniques described in the embodiments of the present invention may also be configured as follows. (1) an outdoor unit equipped with a compressor; At least one primary indoor unit; At least one relay unit connected in parallel to the primary indoor unit; a primary refrigerant circuit in which the primary indoor unit and the pressure reducing mechanism provided in each of the relay units are connected by a refrigerant pipe and in which a primary refrigerant circulates; at least one secondary indoor unit connected to the relay unit; and a secondary refrigerant circuit in which the secondary indoor unit and a circulation pump are connected by refrigerant piping and water as a secondary refrigerant is circulated by operation of the circulation pump; a control device that controls the compressor and the decompression mechanism, The control device When the primary indoor unit and the relay unit are performing heating operation and it is determined that a frost formation determination condition is satisfied, the air conditioner is characterized in that, before starting a defrosting operation, the rotation speed of the compressor is increased and a preheat operation is performed in which the heating operation of the relay unit takes priority over the heating operation of the primary indoor unit. (2) The air conditioner described in (1) above, characterized in that when it is determined that the frost formation determination conditions are met, the control device controls the rate of increase in heating capacity when the preheat operation is performed so that it is greater in the relay unit than in the primary indoor unit, based on the heating capacity in the heating operation before the preheat operation is performed. (3) The air conditioner described in (2) above, characterized in that when it is determined that the frost formation determination conditions are met, the control device controls the opening degree of the pressure reduction mechanism so that the rate of increase in the opening degree of the pressure reduction mechanism when the preheat operation is performed is greater in the relay unit than in the primary indoor unit, based on the opening degree of the pressure reduction mechanism before the preheat operation is performed. (4) The secondary refrigerant circuit is provided in plurality and connected to each of the plurality of relay units, The secondary indoor unit of the secondary refrigerant circuit is either a forced convection type or a natural convection type, The air conditioner described in (2) or (3) above, characterized in that when the preheating operation is performed, the control device controls the opening degree of the pressure reduction mechanism so that the rate of increase in the heating capacity of a relay unit having a larger ratio of the total capacity of the natural convection type secondary indoor units to the total capacity of all secondary indoor units connected to the secondary refrigerant circuit among the multiple relay units. (5) The air conditioner described in (3) or (4) above, characterized in that when the preheat operation is performed, the control device controls the pressure reduction mechanism to increase its opening at a predetermined rate in accordance with the increase in the rotation speed of the compressor, and the predetermined rate of increase is preset so that the pressure reduction mechanism corresponding to the relay unit is larger than the pressure reduction mechanism corresponding to the primary indoor unit. (6) An air conditioner as described in any one of (3) to (5) above, characterized in that when the control device performs the preheat operation on the primary indoor unit and the relay unit, it controls the opening degree of the pressure reduction mechanism in accordance with the target value set for each so that the rate of increase of the heating capacity is greater in the relay unit than in the primary indoor unit. (7) When the control device determines that the frost formation determination condition is satisfied, when performing the preheat operation, the control device calculates a total required output by adding up the required output for the preheat operation for all of the primary indoor units that are performing the heating operation and the required output for the preheat operation for all of the relay units that are performing the heating operation, and calculates the maximum output that the air conditioner can output in the preheat operation, and if the total required output is equal to or greater than the maximum output, performs a preheat operation that prioritizes the heating operation of the relay units over the heating operation of the primary indoor units, as described in (1) above. [Explanation of symbols]

[0129] 1 outdoor unit, 2 primary indoor unit, 3 relay unit, 4 secondary indoor unit, 5 control device, 11 compressor, 12 four-way valve, 13 outdoor heat exchanger, 14 outdoor unit pressure reduction mechanism, 21 primary indoor unit heat exchanger, 22 primary indoor unit pressure reduction mechanism, 23 primary refrigerant temperature sensor, 31 circulation pump, 32 intermediate heat exchanger, 33 secondary refrigerant temperature sensor, 34 relay unit pressure reduction mechanism, 35 primary refrigerant temperature sensor, 41 secondary indoor unit heat exchanger, 51 detection unit, 52 memory unit, 53 determination unit, 54 pressure reduction mechanism control unit, A air conditioner

Claims

1. an outdoor unit equipped with a compressor; At least one primary indoor unit; At least one relay unit connected in parallel to the primary indoor unit; a primary refrigerant circuit in which the primary indoor unit and the pressure reducing mechanism provided in each of the relay units are connected by a refrigerant pipe and in which a primary refrigerant circulates; at least one secondary indoor unit connected to the relay unit; and a secondary refrigerant circuit in which the secondary indoor unit and a circulation pump are connected by refrigerant piping and water as a secondary refrigerant is circulated by operation of the circulation pump; a control device that controls the compressor and the decompression mechanism, The control device When the primary indoor unit and the relay unit are performing heating operation and it is determined that a frost formation determination condition is satisfied, the air conditioner is characterized in that, before starting a defrosting operation, the rotation speed of the compressor is increased and a preheat operation is performed in which the heating operation of the relay unit takes priority over the heating operation of the primary indoor unit.

2. The air conditioner according to claim 1, characterized in that, when it is determined that the frost formation determination condition is satisfied, the control device controls the rate of increase in heating capacity when the preheat operation is performed so that the rate of increase in heating capacity of the relay unit is greater than that of the primary indoor unit, using the heating capacity in the heating operation before the preheat operation as a reference.

3. The air conditioner according to claim 2, characterized in that, when it is determined that the frost formation determination condition is satisfied, the control device controls the opening degree of the pressure reduction mechanism so that the rate of increase in the opening degree of the pressure reduction mechanism when the preheat operation is performed is greater in the relay unit than in the primary indoor unit, based on the opening degree of the pressure reduction mechanism before the preheat operation is performed.

4. a plurality of the secondary refrigerant circuits are provided and connected to the plurality of relay units, respectively; The secondary indoor unit of the secondary refrigerant circuit is either a forced convection type or a natural convection type, The air conditioner according to claim 3, characterized in that when the preheating operation is performed, the control device controls the opening degree of the pressure reduction mechanism so that the rate of increase in the heating capacity of a relay unit having a larger ratio of the total capacity of the natural convection type secondary indoor units to the total capacity of all the secondary indoor units connected to the secondary refrigerant circuit among the plurality of relay units.

5. The air conditioner according to claim 3, characterized in that, when the preheating operation is performed, the control device controls the pressure reduction mechanism to increase its opening at a predetermined rate in accordance with an increase in the rotation speed of the compressor, and the predetermined rate of increase is preset so that the pressure reduction mechanism corresponding to the relay unit has a larger opening than the pressure reduction mechanism corresponding to the primary indoor unit.

6. The air conditioner according to claim 3, characterized in that, when performing the preheating operation on the primary indoor unit and the relay unit, the control device controls the opening degree of the pressure reducing mechanism in accordance with target values ​​set for each so that the rate of increase in the heating capacity of the relay unit is greater than that of the primary indoor unit.

7. The air conditioner according to claim 1, characterized in that when the control device determines that the frost formation determination condition is satisfied, when performing the preheat operation, it calculates a total required output by adding up the required output for the preheat operation for all of the primary indoor units in which the heating operation is being performed and the required output for the preheat operation for all of the relay units in which the heating operation is being performed, and calculates the maximum output that the air conditioner can output in the preheat operation, and if the total required output is equal to or greater than the maximum output, it performs a preheat operation that prioritizes the heating operation of the relay units over the heating operation of the primary indoor units.

Images