Refrigeration equipment

Abstract

To provide a refrigeration device which achieves a further reduction in impact noise of a four-way valve.SOLUTION: A refrigeration device 1 comprises a compressor 11, a four-way switching valve 15, a heat source side heat exchanger 12, a decompression mechanism 13, a user side heat exchanger 14 and a control section 5. The four-way switching valve 15 has a valve body which is moved between a first position allowing a coolant discharged from the compressor 11 to be sent to the heat source side heat exchanger 12 and a second position allowing the coolant discharged from the compressor 11 to be sent to the user side heat exchanger 14. The control section 5 executes: first control causing the valve body to start to be moved from either one of a first position or a second position to the other with frequency of the compressor 11 equal to or less than a predetermined value when switching warming from operation to defrosting operation or from the defrosting operation to the warming operation; and second control making target frequency of the compressor 11 higher than the target frequency thereof when switching from cooling operation to the warming operation after executing the first control.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to refrigeration devices. [Background technology]

[0002] Conventionally, there is known a refrigeration system that can switch between heating operation and cooling operation by switching the flow of the refrigerant circuit with a four-way switching valve. Among such refrigeration systems, there is also a system that performs a defrosting operation to remove frost adhering to an outdoor heat exchanger by performing the same refrigeration cycle as the cooling operation, as disclosed in Patent Document 1, for example.

[0003] It is known that when the four-way valve is switched when the pressure difference between the ports is large, high pressure acts on the port that was under low pressure until just before, generating an impact noise. Patent Document 1 discloses a technology for reducing the pressure difference between the ports by providing a pressure equalization time to reduce the operating frequency of the compressor before switching the four-way valve in order to suppress the impact noise generated by the four-way valve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-83144 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to suppress the impact noise generated in a four-way valve, it is preferable to reduce the pressure difference between the ports. On the other hand, a four-way valve uses the pressure difference between the high pressure port and the low pressure port to move the valve disc to switch the connection destination of the ports. For this reason, if the pressure difference between the ports is made too small, there is a risk of an "intermediate stop" state in which the movement of the valve disc stops before the connection destination of the port is completely switched. If the valve disc stops intermediately, the refrigerant discharged from the compressor may not be sufficiently supplied to the outdoor heat exchanger and the indoor heat exchanger, and it may be difficult for the refrigeration device to function.

[0006] Conventionally, in order to prevent the valve body from stopping midway, it was necessary to switch the four-way valve under a certain pressure difference, which sometimes made it impossible to suppress the impact noise to a level that did not cause discomfort to the user.

[0007] An object of the present disclosure is to further suppress the impact noise generated in a four-way switching valve. [Means for solving the problem]

[0008] (1) A refrigeration device disclosed herein includes a refrigerant circuit having a compressor, a four-way switching valve, a heat source side heat exchanger, a pressure reducing mechanism, and a utilization side heat exchanger, and through which a refrigerant circulates; and a control unit that controls the compressor and the four-way switching valve, wherein the four-way switching valve has a valve body that moves between a first position at which the refrigerant discharged from the compressor is sent to the heat source side heat exchanger and a second position at which the refrigerant discharged from the compressor is sent to the utilization side heat exchanger, and the control unit executes a first control that starts movement of the valve body, which is in one of the first position or the second position, to the other of the first position and the second position while the frequency of the compressor is equal to or lower than a predetermined value, when switching from heating operation to defrost operation, or when switching from defrost operation to heating operation, and a second control that sets a target frequency of the compressor higher than the target frequency of the compressor when switching from cooling operation to heating operation, after the first control.

[0009] In the refrigeration device of the present disclosure, the valve body can be moved by two-stage control, namely, first control and second control. By the first control, the valve body starts to move when the pressure difference between the ports of the four-way switching valve is relatively small, so that the impact noise generated in the four-way switching valve can be further suppressed. Furthermore, even if the valve body stops halfway between the first position and the second position by the first control, the valve body is pushed by the high-pressure refrigerant sent from the compressor by the subsequent second control to move to the other of the first position or the second position (i.e., the normal position), so that a malfunction caused by the valve body stopping halfway can be prevented.

[0010] (2) Preferably, the second control includes control for moving the valve element to the other of the first position or the second position when the valve element is located halfway between the first position and the second position by increasing a frequency of the compressor higher than the predetermined value.

[0011] By configuring in this manner, even if the valve body stops halfway between the first and second positions, the valve body will be pushed by the high-pressure refrigerant sent from the compressor by the subsequent second control and move to the other of the first or second positions (i.e., the normal position), thereby preventing malfunctions caused by the valve body stopping halfway.

[0012] (3) Preferably, a first detection unit that detects an outdoor air temperature is included, and the control unit determines a target frequency of the compressor in the second control in response to the temperature detected by the first detection unit.

[0013] The density of the refrigerant changes depending on the outdoor air temperature. By determining the target frequency of the compressor taking the density of the refrigerant into account, the valve disc can be moved to the normal position more reliably.

[0014] (4) The control unit increases the target frequency of the compressor in the second control as the detected temperature of the first detection unit decreases.

[0015] The lower the outdoor air temperature, the lower the density of the refrigerant, making it more difficult for the refrigerant to move the valve disc. In such a case, by increasing the target frequency of the compressor, the valve disc can be moved to its normal position more reliably.

[0016] (5) After the second control, the control unit executes a third control to reduce the frequency of the compressor.

[0017] After the valve body moves to the normal position, the compressor frequency is lowered, thereby reducing the energy consumption of the compressor.

[0018] (6) A second detection unit is provided that detects a physical quantity that changes depending on the pressure difference between a high pressure port and a low pressure port included in the four-way switching valve, and the control unit executes the third control based on the detection result of the second detection unit.

[0019] Whether or not the valve disc has moved to a normal position can be estimated based on the pressure difference between the high pressure port and the low pressure port. With this configuration, the control unit can execute the third control taking into consideration whether or not the valve disc has moved to a normal position, so that malfunctions caused by the valve disc stopping midway can be more reliably prevented.

[0020] (7) The second control includes a fourth control for gradually increasing the frequency of the compressor toward a predetermined target value.

[0021] By gradually increasing the frequency of the compressor, it is possible to prevent the compressor from becoming overheated.

[0022] (8) A second detection unit is provided that detects a physical quantity that changes depending on a pressure difference between a high pressure port and a low pressure port included in the four-way switching valve, and the second control includes control to stop the fourth control depending on a detection result of the second detection unit.

[0023] Whether or not the valve disc has moved to a normal position can be estimated based on the pressure difference between the high pressure port and the low pressure port. With this configuration, by stopping the fourth control when it is estimated that the valve disc has moved to a normal position, it is possible to prevent the compressor frequency from becoming higher than necessary. This makes it possible to reduce the energy consumption of the compressor. [Brief description of the drawings]

[0024] [Figure 1] 1 is a diagram showing a configuration of a refrigeration device according to an embodiment; [Diagram 2] FIG. 2 is a functional block diagram of the refrigeration device according to the embodiment. [Diagram 3] FIG. 2 is a diagram illustrating the internal structure of the four-way switching valve in a first state. [Figure 4] 4 is a diagram illustrating the internal structure of the four-way switching valve in a second state. FIG. [Diagram 5] FIG. 4 is a diagram illustrating the internal structure of a four-way switching valve in an intermediate stop state. [Figure 6] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 7] 4 is a flowchart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 8] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 9] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. [Figure 10] 4 is a time chart illustrating an example of control of the refrigeration device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0026] [Embodiment] [Refrigeration system configuration] FIG. 1 is a diagram illustrating a schematic configuration of a refrigeration device 1 according to an embodiment. FIG. 2 is a functional block diagram of the refrigeration device 1 according to the embodiment. The configuration of the refrigeration device 1 will be described below with reference to FIGS.

[0027] The refrigeration device 1 functions as an air conditioner that conditions the air in a room R1, and includes an indoor unit 2 installed in the room R1, an outdoor unit 3 installed outdoors, a refrigerant circuit 4 in which a refrigerant circulates, and a control unit 5. The refrigerant is, for example, R32. The use of the room R1 is not particularly limited, and may be, for example, a human living space (for example, a house, a store, an office, a factory), a warehouse for storing foodstuffs, or a space in which machinery and equipment (for example, a server) are installed.

[0028] The refrigerant circuit 4 has a compressor 11, a heat source side heat exchanger 12, a pressure reducing mechanism 13, a utilization side heat exchanger 14, a four way switching valve 15, an accumulator 16, and piping 41 connecting these respective parts 11 to 16. The piping 41 connects the respective parts 11 to 16 so that when the heat source side heat exchanger 12 functions as a condenser (i.e., when the refrigeration device 1 is performing cooling operation), the refrigerant discharged from the compressor 11 flows through the four way switching valve 15, the heat source side heat exchanger 12, the pressure reducing mechanism 13, the utilization side heat exchanger 14, the four way switching valve 15, and the accumulator 16 in this order, and returns to the compressor 11.

[0029] The control unit 5 has an indoor control unit 5a and an outdoor control unit 5b connected to each other by a communication line. As shown in Fig. 2, the indoor control unit 5a has a processor 52a and a memory 53a. The indoor control unit 5a controls the indoor unit 2 by the processor 52a performing various calculations and control based on the programs contained in the memory 53a. The outdoor control unit 5b has a processor 52b and a memory 53b. The outdoor control unit 5b controls the outdoor unit 3 by the processor 52b performing various calculations and control based on the programs contained in the memory 53b.

[0030] The indoor unit 2 houses the utilization side heat exchanger 14 and part of the piping 41 of the refrigerant circuit 4. The indoor unit 2 further houses a detection unit 23 (an example of a "second detection unit" in the present disclosure), an indoor control unit 5a, and an indoor fan 61. The utilization side heat exchanger 14 is, for example, a cross fin tube type heat exchanger. The indoor fan 61 is, for example, a cross flow fan. When the indoor fan 61 operates, air in the room R1 is sucked in from an intake port (not shown) of the indoor unit 2, and the conditioned air that has exchanged heat with the refrigerant in the utilization side heat exchanger 14 is supplied into the room R1 from an exhaust port (not shown) of the indoor unit 2.

[0031] The detection unit 23 detects a physical quantity (temperature) that changes according to the pressure difference between the port P1 (high pressure port) and the port P3 (low pressure port) of the four-way switching valve 15. Specifically, the detection unit 23 is a temperature sensor that is installed, for example, near the air outlet of the indoor unit 2 and detects the temperature of the conditioned air. When the compressor 11 operates with the valve body 82 described below in a normal position (first position or second position), a pressure difference of a predetermined level or more occurs between the ports P1 and P3, and the refrigeration device 1 exerts its cooling capacity (or heating capacity), thereby decreasing (or increasing) the temperature of the conditioned air. The detection unit 23 is electrically connected to the indoor control unit 5a and outputs a detection signal to the indoor control unit 5a.

[0032] A remote control unit 51 (hereinafter referred to as "remote control 51") is attached to the indoor unit 2. The remote control 51 is provided in the room R1 in a state capable of communicating with the indoor control unit 5a via wired or wireless communication, and transmits control signals to the indoor control unit 5a in response to user operations.

[0033] As shown in Fig. 2, the remote control 51 includes an operation switch 71, an operation changeover switch 72, and a temperature setting switch 73. The operation switch 71 switches between operation and stop of the refrigeration device 1 every time it is operated. The operation changeover switch 72 switches the operation mode of the refrigeration device 1 alternately between a cooling operation mode and a heating operation mode every time it is operated. The temperature setting switch 73 includes an up button and a down button, and the set temperature increases every time the up button is operated, and the set temperature decreases every time the down button is operated. Note that the above-mentioned switches 71 to 73 and their operation contents are merely examples, and the remote control 51 may include other switches, or some switches may not be included among the switches 71 to 73.

[0034] The outdoor unit 3 houses the compressor 11, the heat source side heat exchanger 12, the pressure reducing mechanism 13, the four-way switching valve 15, and the accumulator 16 of the refrigerant circuit 4, as well as part of the piping 41. The outdoor unit 3 further houses an outdoor control unit 5b, a detection unit 21 (an example of a “first detection unit” in the present disclosure), a detection unit 22 (an example of a “second detection unit” in the present disclosure), and an outdoor fan 62.

[0035] The compressor 11 is, for example, a variable capacity compressor, and its rotation frequency (hereinafter simply referred to as "frequency") is controlled by an inverter based on an operation command from the control unit 5. The heat source side heat exchanger 12 is, for example, a cross fin tube type heat exchanger. The pressure reducing mechanism 13 is, for example, a solenoid valve (expansion valve), and adjusts the pressure and flow rate of the refrigerant flowing through the piping 41. The accumulator 16 is a device that separates the refrigerant into gas and liquid to protect the compressor 11.

[0036] Four-way switching valve 15 is a valve that switches the flow direction of the refrigerant in pipe 41. Four-way switching valve 15 has four ports P1 to P4 that are respectively connected to regions 41a to 41d of pipe 41. Four-way switching valve 15 is switched between a first state (solid line in FIG. 1) and a second state (dashed line in FIG. 1) under the control of controller 5.

[0037] In the first state, the port P1 and the port P4 communicate with each other, and the port P2 and the port P3 communicate with each other. In the first state, the refrigerant discharged from the compressor 11 to the region 41a is sent to the heat source side heat exchanger 12 through the region 41d. In the second state, the port P1 and the port P2 communicate with each other, and the port P3 and the port P4 communicate with each other. In the second state, the refrigerant discharged from the compressor 11 to the region 41a is sent to the utilization side heat exchanger 14 through the region 41b. The internal structure of the four-way switching valve 15 will be described later.

[0038] The outdoor fan 62 is, for example, a propeller fan. When the outdoor fan 62 operates, outdoor air is sucked in from an intake port (not shown) of the outdoor unit 3, and the air that has exchanged heat with the refrigerant in the heat source side heat exchanger 12 is discharged from an exhaust port (not shown) of the outdoor unit 3 to the outdoor space.

[0039] The detection unit 21 is, for example, a temperature sensor that is installed near the air inlet of the outdoor unit 3 and detects the outdoor air temperature. The detection unit 21 is electrically connected to the outdoor control unit 5b and outputs a detection signal to the outdoor control unit 5b.

[0040] The detection unit 22 detects a physical quantity (pressure difference) that changes according to the pressure difference between the port P1 (high pressure port) and the port P3 (low pressure port) of the four-way switching valve 15. Specifically, the detection unit 22 has a pressure sensor 24 that detects the refrigerant pressure in the region 41a of the pipe 41, and a pressure sensor 25 that detects the refrigerant pressure in the region 41c of the pipe 41. Since the region 41a is connected to the port P1 and the region 41c is connected to the port P3, the pressure difference dP (=PL1-PL2) between the detected pressure PL1 of the pressure sensor 24 and the detected pressure PL2 of the pressure sensor 25 corresponds to the pressure difference between the ports P1 and P3. The pressure sensors 24 and 25 are each electrically connected to the outdoor control unit 5b and output a detection signal to the outdoor control unit 5b.

[0041] [About driving modes] The operation modes of the refrigeration device 1 include a cooling operation mode and a heating operation mode. Based on an instruction received by the remote control 51, the control unit 5 executes the cooling operation mode or the heating operation mode.

[0042] In the cooling operation mode, the refrigeration device 1 performs cooling operation. In the cooling operation, the control unit 5 sets the four-way switching valve 15 to the first state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as a condenser and the utilization side heat exchanger 14 serves as an evaporator.

[0043] The high-pressure refrigerant discharged from the compressor 11 passes through the region 41a, ports P1 and P4 of the four-way switching valve 15, and region 41d, and enters the heat source side heat exchanger 12, where it exchanges heat with the outdoor air and condenses. The condensed refrigerant is depressurized when it passes through the pressure reducing mechanism 13, passes through region 41e, and enters the utilization side heat exchanger 14, where it exchanges heat with the air in room R1 and evaporates. The conditioned air cooled by the refrigerant is blown into room R1 by the indoor fan 61. The refrigerant that leaves the utilization side heat exchanger 14 passes through region 41b, ports P2 and P3 of the four-way switching valve 15, and region 41c, and enters the accumulator 16, where gas-liquid separation occurs, and then the refrigerant is sucked into the compressor 11.

[0044] In the heating operation mode, the refrigeration device 1 alternates between the heating operation and the defrost operation. In the heating operation, the control unit 5 sets the four-way switching valve 15 to the second state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as an evaporator and the utilization side heat exchanger 14 serves as a condenser.

[0045] The high-pressure refrigerant discharged from the compressor 11 passes through the region 41a, ports P1 and P2 of the four-way switching valve 15, and region 41b, and enters the utilization-side heat exchanger 14, where it exchanges heat with the air in the room R1 and condenses. The conditioned air heated by the refrigerant is blown into the room R1 by the indoor fan 61. The condensed refrigerant is depressurized when it passes through the pressure reducing mechanism 13, passes through region 41e, and enters the heat source-side heat exchanger 12, where it exchanges heat with the outdoor air and evaporates. The refrigerant that leaves the heat source-side heat exchanger 12 passes through region 41d, ports P4 and P3 of the four-way switching valve 15, and region 41c, and enters the accumulator 16, where gas-liquid separation occurs, and then the refrigerant is drawn into the compressor 11.

[0046] When a predetermined defrost start condition is satisfied during heating operation, the control unit 5 lowers the frequency of the compressor 11 to perform pressure equalization control described below, and then starts defrost operation. The defrost operation is an operation for melting frost adhering to the heat source side heat exchanger 12. The defrost start condition is, for example, that a predetermined time has elapsed since the start of heating operation. The predetermined time may be set to a constant value in advance, or may be appropriately set by the control unit 5 according to the difference between the temperature of the refrigerant flowing through the heat source side heat exchanger 12 and the outside air temperature.

[0047] In the defrost operation, the control unit 5 sets the four-way switching valve 15 to the first state. When the control unit 5 operates the compressor 11 in this state, a refrigeration cycle is performed in which the heat source side heat exchanger 12 serves as a condenser and the utilization side heat exchanger 14 serves as an evaporator. This causes the heat of the refrigerant to be released in the heat source side heat exchanger 12, and the frost adhering to the heat source side heat exchanger 12 melts.

[0048] When a predetermined defrost end condition is satisfied during the defrost operation, the control unit 5 lowers the frequency of the compressor 11 to perform pressure equalization control described below, and then starts the heating operation. The defrost end condition is, for example, that a predetermined time has elapsed since the start of the defrost operation. The predetermined time may be set to a constant value in advance, or may be appropriately set by the control unit 5 according to the difference between the temperature of the refrigerant flowing through the heat source side heat exchanger 12 and the outside air temperature.

[0049] [Internal structure of four-way switching valve] FIG. 3 is a diagram illustrating the internal structure of four-way switching valve 15 in the first state. FIG. 4 is a diagram illustrating the internal structure of four-way switching valve 15 in the second state.

[0050] The internal structure of the four-way switching valve 15 will be described with reference to Figures 3 and 4. In Figures 3 and 4, cross-sectional areas are hatched. "LP" in Figures 3 and 4 indicates a region where the suction pressure (low pressure) of the refrigerant in the compressor 11 acts, and "HP" indicates a region where the discharge pressure (high pressure) of the refrigerant in the compressor 11 acts.

[0051] The four-way switching valve 15 has a main body portion 8 and a pilot solenoid valve 9 . The main body 8 has a housing 81, a valve body 82, partition plates 83 and 84, a support plate 85, and connection pipes 86 to 89. Four ports P1 to P4 are formed in the housing 81. The valve body 82, the partition plates 83 and 84, and the support plate 85 are housed in the housing 81 in a slidable state.

[0052] The valve body 82 is provided so as to separate a space on the port P1 side from a space on the port P3 side within the housing 81. Partition plates 83 and 84 are plates that separate the inside of the housing 81. The partition plate 83 and the housing 81 form a first chamber S1, and the partition plate 84 and the housing 81 form a second chamber S2.

[0053] The support plate 85 is a plate that transmits the force that moves the partition plates 83 and 84 to the valve body 82. One end of the support plate 85 is connected to the partition plate 83, the other end of the support plate 85 is connected to the partition plate 84, and the central portion of the support plate 85 is connected to the valve body 82. The support plate 85 is formed with a through hole 85a for passing the refrigerant from the port P1 to the port P4, and a through hole 85b for passing the refrigerant from the port P1 to the port P2.

[0054] The connecting pipe 86 is provided on the port P1 side and supplies the pressure (high pressure) acting on the port P1 to the pilot solenoid valve 9. The connecting pipe 87 is provided on the port P3 side and supplies the pressure (low pressure) acting on the port P3 to the pilot solenoid valve 9. The connecting pipe 88 is provided in the first chamber S1 and the pressure supplied from the connecting pipe 86 or the connecting pipe 87 is applied via the pilot solenoid valve 9. The connecting pipe 89 is provided in the second chamber S2 and the pressure supplied from the connecting pipe 86 or the connecting pipe 87 is applied via the pilot solenoid valve 9.

[0055] The pilot solenoid valve 9 has a port 91 communicating with a connecting pipe 86, a port 92 communicating with a connecting pipe 87, a port 93 communicating with a connecting pipe 88, a port 94 communicating with a connecting pipe 89, a valve body (not shown), and a coil mechanism (not shown). The valve body is biased to a position where the port 91 and the port 94 communicate with each other. The coil mechanism receives power from an external power source to generate an electromagnetic force, and the electromagnetic force moves the valve body to a position where the port 91 and the port 93 communicate with each other.

[0056] The control unit 5 controls the voltage applied to the coil mechanism of the pilot solenoid valve 9. When the four-way switching valve 15 is in the first state, the control unit 5 does not apply a voltage to the coil mechanism. As a result, the port 91 and the port 94 communicate with each other, and the high pressure drawn from the connecting pipe 86 acts on the second chamber S2 via the connecting pipe 89. At this time, the port 92 and the port 93 communicate with each other, and the low pressure drawn from the connecting pipe 87 acts on the first chamber S1 via the connecting pipe 88.

[0057] When low pressure acts on the first chamber S1 and high pressure acts on the second chamber S2, the partition plate 83 moves in the direction that narrows the first chamber S1, and the partition plate 84 moves in the direction that widens the second chamber S2. The force that moves the partition plates 83 and 84 is transmitted to the valve body 82 via the support plate 85, and the valve body 82 moves to a position (first position) that covers the ports P2 and P3 as shown in Figure 3. This results in a first state in which the ports P1 and P4 communicate with each other, and the ports P2 and P3 communicate with each other. In the first state, high pressure acts on the ports P1 and P4, and low pressure acts on the ports P2 and P3.

[0058] When the control unit 5 sets the four-way switching valve 15 to the second state, it applies a voltage to the coil mechanism. This causes port 91 to communicate with port 93, and the high pressure drawn from the connecting pipe 86 acts on the first chamber S1 via the connecting pipe 88. At this time, port 92 and port 94 communicate with each other, and the low pressure drawn from the connecting pipe 87 acts on the second chamber S2 via the connecting pipe 89.

[0059] When high pressure acts on the first chamber S1 and low pressure acts on the second chamber S2, the partition plate 83 moves in the direction in which the first chamber S1 becomes wider, and the partition plate 84 moves in the direction in which the second chamber S2 becomes narrower. As a result, the valve body 82 moves to a position (second position) covering the ports P3 and P4 as shown in Fig. 4. This results in a second state in which the ports P1 and P2 communicate with each other, and the ports P3 and P4 communicate with each other. In the second state, high pressure acts on the ports P1 and P2, and low pressure acts on the ports P3 and P4.

[0060] [About impact noise] For example, during defrost operation, the four-way switching valve 15 is in the first state (Fig. 3), and low pressure is applied to port P2. When the operation shifts from defrost operation to heating operation, the four-way switching valve 15 switches to the second state (Fig. 4) by an operation command from the control unit 5, and high pressure from port P1 is applied to port P2, which had been subjected to low pressure until then, and an impact noise is generated due to the pressure change.

[0061] Similarly, when switching from heating operation to defrost operation, high pressure from port P1 acts on port P4, which had previously been under low pressure, and an impact noise is generated due to the pressure change.

[0062] [Regarding pressure equalization control and intermediate stops] In order to suppress the impact noise of the four-way switching valve 15, the control unit 5 performs pressure equalization control to lower the frequency of the compressor 11 to a predetermined value or less before switching the four-way switching valve 15. This reduces the pressure difference between the port P1 and the port P2 (or the port P4), making it possible to suppress the impact noise caused by the pressure change. For this reason, it is preferable to reduce the pressure difference in order to suppress the impact noise.

[0063] On the other hand, the valve element 82 moves by utilizing the pressure difference as described above. Therefore, if the pressure difference becomes too small when the control unit 5 controls the application or stop of the voltage application to the pilot solenoid valve 9, the valve element 82 in the first position (or the second position) may enter an "intermediate stop" state where it stops midway while moving to the second position (or the first position).

[0064] 5 is a diagram illustrating the internal structure of four-way switching valve 15 in an intermediate stop state. For example, consider a case in which, when valve element 82 is in the first position, control unit 5 reduces the frequency of compressor 11 to perform pressure equalization control, and then control unit 5 applies voltage to pilot solenoid valve 9 to start moving valve element 82 from the first position to the second position.

[0065] At this time, the refrigerant pressure on the port P1 side acts on the first chamber S1, and the refrigerant pressure on the port P3 side acts on the second chamber S2. However, when there is almost no difference between the refrigerant pressure on the port P1 side and the refrigerant pressure on the port P3 side due to pressure equalization control, the valve body 82 may stop at a position between the first position and the second position (an intermediate position) after starting to move from the first position toward the second position. For example, as shown in FIG. 5, the valve body 82 stops at or near a position where the areas of the first chamber S1 and the second chamber S2 are equal.

[0066] Depending on the position where the valve element 82 stops, the valve element 82 may not completely close the port P2 (or port P4), and the port P1 and the port P3 may communicate through a gap between the valve element 82 and the port P2 (or port P4). In this case, as shown by the dashed arrow in Fig. 5, a cycle is formed in which most of the refrigerant discharged from the compressor 11 to the region 41a flows from the port P1 through the gap into the port P3, passes through the region 41c and the accumulator 16, and is sucked back into the compressor 11.

[0067] When this cycle is formed, the refrigerant discharged from the compressor 11 is not sufficiently supplied to the heat source side heat exchanger 12 and the utilization side heat exchanger 14, which may make it difficult to exert the capacity (cooling capacity, heating capacity) of the refrigeration device 1. For this reason, in the past, in order to reliably prevent the valve body from stopping at an intermediate position, even when the pressure difference between the ports was reduced by pressure equalization control, the four-way valve was switched in a state where there was a certain degree of pressure difference, and there were cases in which the impact noise could not be sufficiently suppressed.

[0068] The control unit 5 of the refrigeration device 1 executes a first control in which the pressure difference between the port P1 and the port P3 is reduced and then the four-way switching valve 15 is switched, and a second control in which the frequency of the compressor 11 is increased after the first control.

[0069] While the first control, which switches the four-way switching valve 15 with a lower pressure difference, can more reliably suppress the impact noise of the four-way switching valve 15, there are cases where the valve element 82 stops in an intermediate position after the first control. Even in such a case, the valve element 82 is pushed by the higher-pressure refrigerant sent from the compressor 11 by the subsequent second control, and the valve element 82 moves from the intermediate position to the first position or the second position (i.e., the normal position). As a result of performing two-stage control in this manner, it is possible to more reliably suppress the impact noise of the four-way switching valve 15 while preventing malfunctions caused by the valve element 82 stopping midway.

[0070] A specific example of control of the refrigeration device 1 will now be described.

[0071] [First control example of a refrigeration unit] Fig. 6 is a time chart illustrating a first control example of the refrigeration device 1. The upper part of Fig. 6 shows the frequency of the compressor 11, the middle part of Fig. 6 shows the pressure difference dP detected by the detection unit 22, and the lower part of Fig. 6 shows the position of the valve body 82. FIG. 7 is a flowchart illustrating a first control example of the refrigeration device 1.

[0072] In the first control example, the control of the refrigeration device 1 when switching from the defrost operation to the heating operation will be described. Note that the control when switching from the heating operation to the defrost operation differs in that the valve body 82 moves from the second position to the first position, and in other respects the refrigeration device 1 is controlled in the same way, so the description will be omitted.

[0073] During the defrost operation, the valve element 82 is in the first position, and the compressor 11 rotates at the frequency F2, so that the pressure difference dP is greater than a predetermined second threshold value dP2 (dP>dP2). The second threshold value dP2 is the minimum pressure difference required for the valve element 82 to move from the first position to the second position, and is a value obtained, for example, by experiment. During the defrost operation, the control unit 5 monitors whether the above-mentioned defrost end condition is satisfied (step ST1).

[0074] During the defrost operation, when the above-mentioned defrost end condition is satisfied (the "YES" route in step ST1), the control unit 5 reduces the frequency of the compressor 11 to the pressure equalizing frequency F1 (an example of the "predetermined value" in this disclosure) between time t1 and time t2 (step ST2). As a result, the refrigerant pressure (detected pressure PL1) at the ports P1 and P4 to which high pressure acts decreases, and the refrigerant pressure (detected pressure PL2) at the ports P2 and P3 to which low pressure acts increases, so that the pressure difference dP (=PL1-PL2) decreases after time t1.

[0075] After setting the frequency of the compressor 11 to F1 at time t2, the control unit 5 monitors whether the pressure difference dP has become equal to or less than a predetermined first threshold value dP1 based on the pressures PL1 and PL2 detected by the detection unit 22 (step ST3). Here, the first threshold value dP1 is equal to or less than the second threshold value dP2. If the pressure difference dP is greater than the first threshold value dP1 (dP>dP1, route of "NO" in step ST3), the control unit 5 maintains the frequency of the compressor 11 at F1 and performs pressure equalization of the four-way switching valve 15.

[0076] When the pressure difference dP is equal to or less than the first threshold value dP1 (dP≦dP1, route "YES" in step ST3), the control unit 5 controls the voltage applied to the pilot solenoid valve 9 to start the movement of the valve element 82 from the first position to the second position (first control: step ST4). If the pressure difference dP at the time when the first control is performed is sufficiently low, the valve element 82 may not even budge from the first position. Even in such a case, the control unit 5 at least controls the voltage applied to the pilot solenoid valve 9 so that the valve element 82 moves to the second position, and therefore this is included in the control "to start the movement of the valve element 82 from the first position to the second position."

[0077] 6, since the pressure difference dP becomes equal to the first threshold value dP1 at time t3, the control unit 5 starts moving the valve element 82 at time t3 (or immediately thereafter). Since the pressure difference dP at the time of switching is small, the impact noise of the four-way switching valve 15 can be suppressed as described above, but the valve element 82 may stop in an intermediate position.

[0078] Although Figure 6 shows an example in which the valve body 82 stops at an intermediate position, even if the first control is executed when the pressure difference dP is equal to or less than the first threshold value dP1, depending on the conditions (e.g., the weather on that day), the valve body 82 may be able to move completely to the second position (normal position).

[0079] For example, when the first threshold value dP1 is equal to the second threshold value dP2 (the minimum pressure difference necessary for the valve body 82 to move from the first position to the second position), if the control unit 5 executes the first control when the pressure difference dP is exactly at the first threshold value dP1, the valve body 82 can move completely from the first position to the second position. However, the pressure difference dP is constantly fluctuating, and there may be a lag in the timing of the control unit 5 issuing an instruction. For this reason, even if the control unit 5 is configured to execute the first control when the pressure difference dP is at the first threshold value dP1, the control unit 5 may actually execute the first control when the pressure difference is lower than dP1 due to an error, lag, etc. In such a case, the valve body 82 may stop at an intermediate position.

[0080] The first threshold value dP1 does not have to be a pressure difference that almost certainly stops the valve body 82 at the intermediate position (for example, a pressure difference that stops the valve body 82 intermediately 90 times or more out of 100 switching operations). For example, the first threshold value dP1 may be a pressure difference that is on the verge of whether the valve body 82 stops at the intermediate position or moves to the normal position (for example, a pressure difference that stops the valve body 82 intermediately about 50 times out of 100 switching operations), or a pressure difference that moves the valve body 82 to the normal position in most cases but may stop the valve body 82 at the intermediate position in some cases (for example, a pressure difference that stops the valve body 82 intermediately about once out of 100 switching operations).

[0081] The control unit 5 determines the target frequency in the second control based on the temperature detected by the detection unit 21, for example, between time t2 and time t3. Specifically, the lower the detected temperature, the higher the target frequency determined by the control unit 5. For example, the control unit 5 determines the target frequency F3 (solid line in FIG. 6) when the detected temperature is Tp1, and determines the target frequency F4 (phantom line in FIG. 6) higher than the frequency F3 when the detected temperature is Tp2, which is lower than the temperature Tp1 (Tp2<Tp1のときF4> The target frequencies F3 and F4 are both higher than the target frequency (frequency F2 in this embodiment) when switching from cooling operation to heating operation, which will be described later (F3>F2 and F4>F2).

[0082] The density of the refrigerant changes depending on the outdoor air temperature. Specifically, the lower the outdoor air temperature, the lower the density of the refrigerant, making it more difficult for the refrigerant to move the valve body 82. In such a case, by increasing the target frequency of the compressor 11 in the second control and increasing the flow rate of the refrigerant that presses the valve body 82, the valve body 82 can be more reliably moved to the second position (normal position) in the second control.

[0083] Between time t3 and time t4, the control unit 5 increases the frequency of the compressor 11 from frequency F1 to the target frequency (for example, F3) (second control: step ST5). As a result, since a higher-pressure refrigerant is discharged from the compressor 11, when the valve body 82 is in the intermediate position, the high-pressure refrigerant can push the valve body 82 to move it to the second position (normal position). If the valve body 82 has already moved to the second position before the second control due to the movement of the valve body 82 by the first control, the valve body 82 hardly moves and remains in the second position even when high-pressure refrigerant is supplied in the second control.

[0084] After the second control, the control unit 5 executes a third control to lower the frequency of the compressor 11. Specifically, after the control unit 5 causes the frequency of the compressor 11 to reach the target frequency F3 at time t4, based on the detection unit 22, it monitors whether the pressure difference dP has become equal to or greater than the second threshold value dP2 (step ST6). Here, the second threshold value dP2 is the pressure difference obtained when the valve body 82 moves to the second position (normal position), and is, for example, a value obtained by experiment. When the pressure difference dP is smaller than the second threshold value dP2 (dP < dP2, the "NO" route in step ST6), the control unit 5 maintains the compressor 11 at the target frequency F3 and continues to supply high-pressure refrigerant to promote the movement of the valve body 82 to the second position.

[0085] When the pressure difference dP is equal to or greater than the second threshold value dP2 (dP ≧ dP2, the "YES" route in step ST6), it can be estimated that the movement of the valve body 82 to the second position is completed. Therefore, the control unit 5 decreases the frequency of the compressor 11 from F3 to F2 (third control: step ST7). In the case of FIG. 6, since the pressure difference dP becomes equal to the second threshold value dP2 at time t5, the control unit 5 lowers the frequency of the compressor 11 at time t5 (or immediately thereafter). Thereby, while more surely preventing the problem due to the intermediate stop of the valve body 82, after the movement of the valve body 82 is completed, the energy consumption of the compressor 11 can be reduced by lowering the frequency of the compressor 11.

[0086] The control unit 5 may determine whether to perform the third control depending on the heating load. For example, when the heating load is higher than a predetermined load (for example, when the temperature of the room R1 is lower than the set temperature set by the remote control 51 by a predetermined value or more), it is preferable that the control unit 5 heats the room R1 more strongly by increasing the frequency of the compressor 11.

[0087] For this reason, when the heating load is higher than a predetermined load, the control unit 5 maintains the frequency of the compressor 11 at F3 until the room R1 is sufficiently heated without performing the third control. On the other hand, when the heating load is equal to or lower than the predetermined load, there is little need to strongly heat the room R1, so the control unit 5 performs the third control to make the frequency of the compressor 11 lower than F3. In this way, there are cases where the control unit 5 does not perform the third control.

[0088] After time t5, with the valve body 82 in the second position, the compressor 11 rotates at a frequency F2, and the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the utilization side heat exchanger 14, and the refrigeration device 1 performs heating operation.

[0089] [Second control example of refrigeration equipment] 8 is a time chart illustrating a second control example of the refrigeration device 1. The second control example includes control for the refrigeration device 1 to transition from cooling operation to heating operation. The transition from cooling operation to heating operation is executed, for example, when a user operates the operation changeover switch 72 of the remote control 51 during cooling operation to switch the operation mode from the cooling operation mode to the heating operation mode.

[0090] During cooling operation, the compressor 11 rotates at a frequency F2 with the valve body 82 in the first position. When the operation mode is switched to the heating operation mode during cooling operation, the control unit 5 reduces the frequency of the compressor 11 from frequency F2 to frequency F1 between time t11 and time t12. As a result, the pressure difference dP decreases after time t11.

[0091] After setting the frequency of the compressor 11 to F1 at time t12, the control unit 5 monitors whether the pressure difference dP has become equal to or less than the first threshold value dP1, based on the pressures PL1 and PL2 detected by the detection unit 22. If the pressure difference dP is greater than the first threshold value dP1 (dP>dP1), the control unit 5 maintains the frequency of the compressor 11 at F1 and performs pressure equalization of the four-way switching valve 15.

[0092] When the pressure difference dP is equal to or less than the first threshold value dP1 (dP≦dP1), the control unit 5 increases the frequency of the compressor 11. In the case of Fig. 8, since the pressure difference dP becomes equal to the first threshold value dP1 at time t13, the control unit 5 increases the frequency of the compressor 11 by setting the target frequency to F2 at time t13 (or immediately thereafter). As a result, the pressure difference dP increases after time t13.

[0093] When the pressure difference dP becomes equal to or greater than the third threshold value dP3, the control unit 5 controls the voltage applied to the pilot solenoid valve 9 to start the movement of the valve element 82 from the first position to the second position. In the case of FIG. 8, the pressure difference dP becomes equal to the third threshold value dP3 at time t14, so the control unit 5 starts the movement of the valve element 82 at time t14 (or immediately thereafter). The third threshold value dP3 is a value greater than the first threshold value dP1 (dP3>dP1), and is a pressure difference that can reliably switch the four-way switching valve 15. For this reason, after time t14, the valve element 82 can completely move from the first position to the second position, but the impact noise of the four-way switching valve 15 may not be suppressed.

[0094] However, when switching from cooling operation to heating operation, the user operates the remote control 51 by himself, so even if some impact noise occurs, the user understands that the cause of the impact noise is the switching of the refrigeration device, and is unlikely to feel uncomfortable. Therefore, when switching from cooling operation to heating operation, the control unit 5 prioritizes switching the four-way switching valve 15 quickly and reliably.

[0095] After the frequency of the compressor 11 reaches the target frequency F2, the control unit 5 rotates the compressor 11 at the frequency F2. In this control example, the four-way switching valve 15 is not stopped intermediately, so there is no need to set a higher target frequency (e.g., F3) as in the first control example. By rotating the compressor 11 at the frequency F2 with the valve body 82 in the second position, the refrigeration cycle of the refrigeration device 1 becomes a cycle in which the refrigerant discharged from the compressor 11 is sent to the utilization side heat exchanger 14, and the refrigeration device 1 performs heating operation.

[0096] In the above, the operation of switching from cooling operation to heating operation has been described. For example, the refrigeration device 1 may be operated in cooling operation mode in summer, then the power supply to the refrigeration device 1 may be turned off (i.e., the compressor 11 may be stopped), and then, in autumn, the refrigeration device 1 may be started to operate in heating operation mode in winter. This case will be described below.

[0097] In this case, the valve element 82 of the refrigeration device 1 that has started operating in a heating operation mode in winter is in the first position, and the refrigerant circuit 4 is connected for cooling operation. Therefore, the control unit 5 starts the rotation of the compressor 11 and increases the frequency of the compressor 11 to the target frequency F2. Then, when the pressure difference dP becomes equal to or greater than the third threshold value dP3 (i.e., when the valve element 82 is reliably movable), the control unit 5 controls the voltage applied to the pilot solenoid valve 9 to move the valve element 82 from the first position to the second position.

[0098] In the first control example (FIG. 6) and this control example (FIG. 8), the frequency during normal operation of the compressor 11 in cooling operation, heating operation, and defrost operation is described as F2, but the frequency during normal operation of the compressor 11 may be a value other than F2 as long as it is a value larger than F1, and is not particularly limited. In the control examples (FIGS. 9 and 10) described later, the frequency during normal operation will also be described as F2 for simplicity.

[0099] [Third control example of refrigeration equipment] 9 is a time chart for explaining a third control example of the refrigeration device 1. In the third control example, the control of the compressor 11 and the four-way switching valve 15 up to time t3 is performed in the same manner as in the first control example, and therefore the explanation will be omitted as appropriate.

[0100] In the first control example, in the second control, the control unit 5 increases the frequency of the compressor 11 in one go from F1 during pressure equalization control to the target frequency F3, as shown from time t3 to time t4 in Fig. 6. Then, the control unit 5 maintains the frequency of the compressor 11 at F3 from time t4 to time t5, thereby moving the valve body 82, which is in the intermediate position, to the second position.

[0101] In this control example, the control unit 5 performs a fourth control in which the frequency of the compressor 11 is increased stepwise toward a predetermined target frequency F14 that is higher than the frequency F2 in the second control (F14>F2). The control unit 5 monitors whether the pressure difference dP detected by the detection unit 22 in the fourth control is equal to or greater than the second threshold value dP2, and when the pressure difference dP is equal to or greater than the second threshold value dP2, stops the fourth control and maintains the frequency at the time of stopping.

[0102] Specifically, similar to the first control example, the control unit 5 determines a target frequency in the second control in accordance with the temperature detected by the detection unit 21 between time t2 and time t3. In the example of Fig. 9, the target frequency is set to F14. Furthermore, the control unit 5 determines one or more frequencies F11, F12, F13 that are greater than the frequency F1 and less than the target frequency F14.

[0103] After time t3, the control unit 5 increases the frequency of the compressor 11 from F1 to F11, and waits for a predetermined time while maintaining the frequency at F11. The control unit 5 monitors whether the pressure difference dP detected by the detection unit 22 during standby has become equal to or greater than the second threshold value dP2. In the example of Fig. 9, since the pressure difference dP is not equal to or greater than the second threshold value dP2, the control unit 5 waits for a predetermined time, increases the frequency from F11 to F12, and waits for a further predetermined time while maintaining the frequency at F12.

[0104] In this way, the control unit 5 increases the frequency of the compressor 11 in a stepwise manner until the pressure difference dP becomes equal to or greater than the second threshold value dP2. In the example of Fig. 9, after the control unit 5 increases the frequency from F12 to F13, the pressure difference dP becomes equal to or greater than the second threshold value dP2 during a predetermined standby time, so the control unit 5 stops the fourth control for gradually increasing the frequency of the compressor 11, and keeps the frequency of the compressor 11 at F13.

[0105] According to this control example, by increasing the frequency of the compressor 11 in a stepwise manner, it is possible to prevent the compressor 11 from becoming overheated. Furthermore, by stopping the fourth control when it is estimated that the valve body 82 has moved to a normal position (for example, when the pressure difference dP becomes equal to or greater than the second threshold value dP2 as described above), it is possible to prevent the frequency of the compressor 11 from becoming higher than necessary. This makes it possible to reduce the energy consumption of the compressor.

[0106] Note that the "target frequency" is a target value, and depending on the control conditions, the target frequency may not actually be reached. As in the example of Fig. 9, even if the control unit 5 determines the target frequency to be a frequency F14 higher than the frequency F2 during normal operation, if the valve element 82 moves to a normal position early in the second control (or if the valve element 82 is not stopped midway and is in a normal position at the start of the second control), the frequency F13 that is actually reached will be lower than the target frequency F14. Also, as in the example of Fig. 9, the frequency F13 may be lower than the frequency F2.

[0107] [Fourth control example of refrigeration equipment] 10 is a time chart for explaining a fourth control example of the refrigeration device 1. In the fourth control example, the control of the compressor 11 and the four-way switching valve 15 up to time t4 is performed in the same manner as in the first control example, and therefore the explanation will be omitted as appropriate.

[0108] In the first control example, the control unit 5 performs a third control to lower the frequency after the second control, triggered by the pressure difference dP detected by the detection unit 22 becoming equal to or greater than the second threshold value dP2. In contrast, in this control example, the control unit 5 performs a third control to lower the frequency after the second control, triggered by the temperature detected by the detection unit 23 (temperature sensor that detects the temperature of the conditioned air) becoming equal to or greater than the threshold value Th1.

[0109] As described above, when the valve body 82 stops at the intermediate position and most of the refrigerant discharged from the compressor 11 is no longer supplied to the heat source side heat exchanger 12 and the utilization side heat exchanger 14, the cooling capacity and heating capacity are not exerted. For this reason, as shown in the example of Fig. 10, from time t3 to time t7 until the defrost operation is switched to the heating operation (while the valve body 82 is in the intermediate position), the indoor unit 2 cannot heat the room R1, so the detected temperature of the detection unit 23 hardly increases or the detected temperature of the detection unit 23 decreases.

[0110] By the second control of the control unit 5, the compressor 11 is rotated at the frequency F3 after time t4, and the valve body 82 moves to the second position (normal position) at time t7. As a result, refrigerant is supplied to the heat source side heat exchanger 12 and the utilization side heat exchanger 14, and the refrigerant circulates through a normal refrigeration cycle, and the indoor unit 2 starts heating the room R1. Therefore, the detected temperature of the detection unit 23 increases after time t7.

[0111] When the temperature detected by the detector 23 becomes equal to the threshold value Th1 at time t8, the controller 5 determines that the valve body 82 has moved to the second position, and sets the frequency of the compressor 11 to the normal operation frequency F2 (third control). This makes it possible to reduce the energy consumption of the compressor 11.

[0112] [Variations] The present disclosure is not limited to the above embodiment, and various modifications are possible. In the following modifications, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0113] In the above control example, the control unit 5 controls the compressor 11 and the four-way switching valve 15 based on the pressures PL1, PL2 detected by the detection unit 22. However, the control unit 5 may control the compressor 11 and the four-way switching valve 15 based on a time previously obtained by an experiment. In this case, the refrigeration device 1 does not need to include the detection unit 22.

[0114] For example, in the first control example, the pressure difference dP becoming equal to or smaller than the first threshold value dP1 is used as a trigger to switch the four-way switching valve 15 at time t3 (first control), and the frequency of the compressor 11 is increased to the target frequency F3 between time t3 and time t4 (second control).Then, the pressure difference dP becoming equal to or larger than the second threshold value dP2 is used as a trigger to lower the frequency of the compressor 11 at time t5 (third control).

[0115] In contrast to this, in this modified example, for example, the time from time t1 to time t3 and the time from time t4 to time t5 are obtained in advance by experiment, and the control unit 5 controls the compressor 11 and the four-way switching valve 15 based on these obtained times.

[0116] [others] At least some of the above-described embodiments and modified examples may be combined with each other in any desired manner.

[0117] [Effects of the embodiment] (1) The refrigeration device 1 of the embodiment includes a compressor 11, a four-way switching valve 15, a heat source side heat exchanger 12, a pressure reducing mechanism 13, and a utilization side heat exchanger 14. The refrigerant circuit 4 has a refrigerant circulating therein, and a control unit 5 that controls the compressor 11 and the four-way switching valve 15. The four-way switching valve 15 has a valve body 82 that moves between a first position where the refrigerant discharged from the compressor 11 is sent to the heat source side heat exchanger 12 and a second position where the refrigerant discharged from the compressor 11 is sent to the utilization side heat exchanger 14. The control unit 5 When switching from heating operation to defrost operation, or when switching from defrost operation to heating operation, a first control is executed to start moving a valve body 82, which is in one of the first position and the second position, to the other of the first position and the second position while the frequency of the compressor 11 is equal to or lower than a predetermined value, and a second control is executed to set a target frequency of the compressor 11 higher than a target frequency of the compressor 11 when switching from cooling operation to heating operation after the first control.

[0118] In the refrigeration device 1 of the embodiment, the valve element 82 can be moved by two-stage control, namely, the first control and the second control. By the first control, the valve element 82 starts to move when the pressure difference dP between the ports P1, P3 of the four-way switching valve 15 is relatively small, so that the impact noise generated in the four-way switching valve 15 can be further suppressed. Furthermore, even if the valve element 82 stops halfway between the first position and the second position by the first control, the valve element 82 moves to the other of the first position or the second position (i.e., the normal position) by being pushed by the high-pressure refrigerant sent from the compressor 11 by the subsequent second control, so that a malfunction caused by the valve element 82 stopping halfway can be prevented.

[0119] (2) The second control of the embodiment includes control to move the valve body 82 to the other of the first position or the second position when the valve body 82 is halfway between the first position and the second position by increasing the frequency of the compressor 11 above the predetermined value.

[0120] With this configuration, even if the first control causes the valve body 82 to stop halfway between the first and second positions, the subsequent second control will cause the valve body 82 to move to the other of the first or second positions (i.e., the normal position) by being pushed by the high-pressure refrigerant sent from the compressor 11, thereby preventing a malfunction caused by the valve body 82 stopping midway.

[0121] (3) The refrigeration device 1 of the embodiment is equipped with a first detection unit 21 that detects the outdoor air temperature, and the control unit 5 determines the target frequency of the compressor 11 in the second control in accordance with the detected temperature of the first detection unit 21.

[0122] The density of the refrigerant changes depending on the outdoor air temperature. By determining the target frequency of the compressor 11 taking the density of the refrigerant into consideration, it is possible to more reliably move the valve body 82 to the normal position.

[0123] (4) In the embodiment, the control unit 5 increases the target frequency of the compressor 11 in the second control as the detected temperature of the first detection unit 21 decreases.

[0124] The lower the outdoor air temperature, the lower the density of the refrigerant, making it more difficult for the refrigerant to move the valve body 82. In such a case, by increasing the target frequency of the compressor 11, the valve body 82 can be moved to the normal position more reliably.

[0125] (5) In the embodiment, the control unit 5 executes the third control to lower the frequency of the compressor 11 after the second control.

[0126] After the valve body 82 has moved to the normal position, the frequency of the compressor 11 is lowered, so that the energy consumption of the compressor 11 can be reduced.

[0127] (6) The four-way switching valve 15 is provided with second detection units 22, 23 that detect a physical quantity that changes depending on the pressure difference between the high pressure port P1 and the low pressure port P3, and the control unit 5 executes the third control based on the detection results of the second detection units 22, 23.

[0128] It is possible to estimate whether or not the valve element 82 has moved to a normal position based on the pressure difference dP between the high pressure port P1 and the low pressure port P3. With this configuration, the control unit 5 can execute the third control taking into consideration whether or not the valve element 82 has moved to a normal position, so that it is possible to more reliably prevent malfunctions caused by the valve element 82 stopping midway.

[0129] (7) The second control of the embodiment includes a fourth control in which the frequency of the compressor 11 is increased stepwise toward a predetermined target frequency.

[0130] By increasing the frequency of the compressor 11 in stages, it is possible to prevent the compressor from becoming overheated.

[0131] (8) The refrigeration device 1 of the embodiment is provided with second detection units 22, 23 that detect a physical quantity that changes depending on the pressure difference between the high pressure port P1 and the low pressure port P3 included in the four-way switching valve 15, and the second control includes control to stop the fourth control depending on the detection result of the second detection units 22, 23.

[0132] It is possible to estimate whether the valve element 82 has moved to a normal position based on the pressure difference dP between the high pressure port P1 and the low pressure port P3. With this configuration, by stopping the fourth control when it is estimated that the valve element 82 has moved to a normal position, it is possible to prevent the frequency of the compressor 11 from becoming higher than necessary. This makes it possible to reduce the energy consumption of the compressor 11.

[0133] [Additional Note] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Explanation of symbols]

[0134] 1: refrigeration device, 11: compressor, 12: heat source side heat exchanger, 13: pressure reducing mechanism, 14: utilization side heat exchanger, 15: four-way switching valve, 16: accumulator, 2: indoor unit, 21: detection unit, 22: detection unit, 23: detection unit, 24: pressure sensor, 25: pressure sensor, 3: outdoor unit, 4: refrigerant circuit, 41: piping, 41a: area, 41b: area, 41c: area, 41d: area, 41e: area, 5: control unit, 5a: Indoor control unit, 5b: outdoor control unit, 51: remote control unit (remote control), 52a: processor, 52b: processor, 53a: memory, 53b: memory, 61: indoor fan, 62: outdoor fan, 71: operation switch, 72: operation changeover switch, 73: temperature setting switch, 8: main body, 81: housing, 82: valve body, 83: partition plate, 84: partition plate, 85: support plate, 85a: through hole, 85b: through hole Through hole, 86: connecting pipe, 87: connecting pipe, 88: connecting pipe, 89: connecting pipe, 9: pilot solenoid valve, 91: port, 92: port, 93: port, 94: port, R1: chamber, P1: port, P2: port, P3: port, P4: port, S1: first chamber, S2: second chamber, F1: frequency (predetermined value), F2: frequency (target frequency), F3: frequency (target frequency), F4: frequency (target frequency), F11: frequency number, F12: frequency, F13: frequency, F14: frequency (target frequency), t1: time, t2: time, t3: time, t4: time, t5: time, t7: time, t8: time, t11: time, t12: time, t13: time, t14: time, PL1: detected pressure, PL2: detected pressure, dP: pressure difference, dP1: first threshold, dP2: second threshold, dP3: third threshold, Th1: threshold, Tp1: detected temperature, Tp2: detected temperature

Claims

1. a refrigerant circuit (4) having a compressor (11), a four-way switching valve (15), a heat source side heat exchanger (12), a pressure reducing mechanism (13) and a utilization side heat exchanger (14), in which a refrigerant circulates; a control unit (5) that controls the compressor (11) and the four-way switching valve (15); Equipped with The four-way switching valve (15) has a valve body (82) that moves between a first position where the refrigerant discharged from the compressor (11) is sent to the heat source side heat exchanger (12) and a second position where the refrigerant discharged from the compressor (11) is sent to the utilization side heat exchanger (14), The control unit (5) a first control that starts movement of the valve body (82), which is in one of the first position and the second position, to the other of the first position and the second position when switching from a heating operation to a defrost operation or when switching from the defrost operation to the heating operation, in a state in which a frequency of the compressor (11) is equal to or lower than a predetermined value; and executing, after the first control, a second control for setting a target frequency of the compressor (11) higher than a target frequency of the compressor (11) when switching from a cooling operation to a heating operation. Refrigeration device (1).

2. the second control includes control for moving the valve disc (82) to the other of the first position or the second position when the valve disc (82) is located halfway between the first position and the second position by making a frequency of the compressor (11) higher than the predetermined value. Refrigeration device (1) according to claim 1.

3. A first detection unit (21) for detecting an outdoor air temperature is provided, The control unit (5) determines a target frequency of the compressor (11) in the second control in response to the detected temperature of the first detection unit (21). Refrigeration device (1) according to claim 1 or claim 2.

4. the control unit (5) increases a target frequency of the compressor (11) in the second control as the detected temperature of the first detection unit (21) decreases. Refrigeration device (1) according to claim 3.

5. The control unit (5) executes a third control to reduce a frequency of the compressor (11) after the second control. Refrigeration device (1) according to any one of claims 1 to 4.

6. a second detection unit (22, 23) that detects a physical quantity that changes depending on a pressure difference between a high pressure port (P1) and a low pressure port (P3) included in the four-way switching valve (15), The control unit (5) executes the third control based on a detection result of the second detection unit (22, 23). Refrigeration device (1) according to claim 5.

7. The second control includes a fourth control for gradually increasing a frequency of the compressor (11) toward a predetermined target frequency. Refrigeration device (1) according to any one of the preceding claims.

8. a second detection unit (22, 23) that detects a physical quantity that changes depending on a pressure difference between a high pressure port (P1) and a low pressure port (P3) included in the four-way switching valve (15), The second control includes control of stopping the fourth control depending on a detection result of the second detection unit (22, 23). Refrigeration device (1) according to claim 7.

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