Refrigerating device having four-way switching valve

Abstract

To restrain blockage of a switch operation of a four-way switching valve due to refrigeration oil clogged in a refrigerant flow path of the four-way switching valve.SOLUTION: A refrigerating device 100 comprises a compressor 11, a four-way switching valve 12, a heat source heat-exchanger 13, a utilization heat-exchanger 23, and a control part 9. The compressor 11 compresses a refrigerant R. The four-way switching valve 12 switches a first refrigeration cycle and a second refrigeration cycle. In the first refrigeration cycle, the heat source heat-exchanger 13 functions as a heat radiator, and the utilization heat exchanger 23 functions as a heat sink. In the second refrigeration cycle, the heat source heat-exchanger 13 functions as a heat sink, and the utilization heat exchanger 23 functions as a heat radiator. The control part 9 performs an oil discharge operation for discharging refrigeration oil remained inside the four-way switching valve 12 to outside of the four-way switching valve 12, before switching the four-way switching valve 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration system having a four-way selector valve. [Background technology]

[0002] The four-way switching valve disclosed in Patent Document 1 (JP 63-015056 A) is installed in a refrigeration system to switch the circulation direction of a refrigerant. This four-way switching valve is a so-called differential pressure driven type, and the valve element is moved by utilizing the pressure of the refrigerant passing through the valve chamber. Summary of the Invention [Problem to be solved by the invention]

[0003] A differential pressure driven four-way selector valve has many narrow refrigerant flow paths. If the refrigerant flow paths become clogged with refrigeration oil, the movement of the refrigerant is hindered, which can ultimately cause problems with the switching operation of the four-way selector valve. [Means for solving the problem]

[0004] A refrigeration system according to a first aspect includes a compressor, a four-way switching valve, a heat source heat exchanger, a utilization heat exchanger, and a control unit. The compressor compresses a refrigerant. The four-way switching valve switches between a first refrigeration cycle and a second refrigeration cycle. In the first refrigeration cycle, the heat source heat exchanger functions as a radiator and the utilization heat exchanger functions as a heat absorber. In the second refrigeration cycle, the heat source heat exchanger functions as a heat absorber and the utilization heat exchanger functions as a radiator. The control unit performs an oil discharge operation to discharge refrigeration oil remaining inside the four-way switching valve to the outside of the four-way switching valve before switching the four-way switching valve.

[0005] According to this configuration, the refrigeration oil inside the four-way selector valve is discharged by the oil discharge operation before the switching operation of the four-way selector valve, thereby reducing the risk of the switching of the four-way selector valve failing due to the refrigeration oil remaining inside the four-way selector valve.

[0006] A refrigeration apparatus according to a second aspect is the refrigeration apparatus according to the first aspect, wherein the control unit performs the oil discharge operation when the pressure difference between the refrigerant on the suction side and the discharge side of the compressor is smaller than a predetermined value.

[0007] According to this configuration, the oil discharge operation is performed when the switching of the four-way switching valve has failed, which makes it easier for the four-way switching valve to be switched again successfully.

[0008] A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the first or second aspect, wherein the four-way selector valve has a valve chamber, a valve element, a first pilot chamber, a second pilot chamber, a first port, a second port, a third port, and a fourth port formed in the valve chamber, a first pilot solenoid valve, a second pilot solenoid valve, a communication passage, a first flow path, a second flow path, and a third flow path. The valve element slides within the valve chamber. The first pilot chamber is formed at an end of the valve chamber. The second pilot chamber is formed at an end of the valve chamber opposite the first pilot chamber. The first port receives refrigerant discharged from the compressor. The second port ejects refrigerant drawn into the compressor. The third port transfers refrigerant to and from the heat source heat exchanger. The fourth port transfers refrigerant to and from the utilization heat exchanger. The first pilot solenoid valve, the second pilot solenoid valve, and the communication passage communicate the first pilot solenoid valve and the second pilot solenoid valve. The first flow path connects the first pilot chamber to the communication path when the first pilot solenoid valve is open. The second flow path connects the second pilot chamber to the communication path when the second pilot solenoid valve is open. The third flow path connects the communication path to the second port. When performing the oil discharge operation, the control unit operates the compressor and opens both the first pilot solenoid valve and the second pilot solenoid valve, thereby discharging refrigeration oil remaining in the valve chamber, the first flow path, or the second flow path to the outside of the four-way selector valve.

[0009] According to this configuration, in the oil discharge operation, refrigeration oil in the first or second flow path is discharged by opening both the first and second pilot solenoid valves, thereby reducing the obstruction of the movement of the valve body by refrigeration oil that has entered the first or second pilot chamber.

[0010] A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the third aspect, wherein, in the oil discharging operation, the control section keeps both the first pilot solenoid valve and the second pilot solenoid valve open.

[0011] According to this configuration, both the first and second pilot solenoid valves are continuously opened during the oil discharge operation, so that refrigeration oil remaining in the first flow path or the second flow path continues to be sucked by the compressor.

[0012] A refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to the third aspect, wherein, in the oil discharging operation, the control unit repeatedly opens and closes at least one of the first pilot solenoid valve and the second pilot solenoid valve.

[0013] According to this configuration, at least one of the first and second pilot solenoid valves is repeatedly opened and closed during the oil discharge operation, thereby urging the movement of refrigeration oil in the first flow path or the second flow path.

[0014] A refrigeration device of a sixth aspect is a refrigeration device of any one of the third aspect to the fifth aspect, wherein after the oil discharge operation continues for a predetermined time, the control unit closes either the first pilot solenoid valve or the second pilot solenoid valve.

[0015] According to this configuration, after the oil discharge operation is completed, one of the first and second pilot solenoid valves is closed, thereby appropriately switching the four-way switching valve.

[0016] A refrigeration apparatus according to a seventh aspect is the refrigeration apparatus according to any one of the third aspect to the sixth aspect, wherein the four-way switching valve is arranged so that the second port faces downward.

[0017] According to this configuration, the discharge of refrigeration oil is promoted in the oil discharge operation. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a circuit diagram showing the configuration of a refrigeration device 100. FIG. [Figure 2]FIG. 2 is a cross-sectional schematic view showing the four-way switching valve 12 in cold energy utilization operation. [Figure 3] 4 is another schematic cross-sectional view showing the four-way switching valve 12 in a transient state. FIG. [Figure 4] FIG. 10 is another cross-sectional schematic view showing the four-way switching valve 12 in the heat utilization operation. [Figure 5] FIG. 2 is a block diagram showing an electrical system of the refrigeration device 100. [Figure 6] FIG. 2 is a cross-sectional schematic view showing a four-way switching valve 12 filled with refrigerating machine oil. [Figure 7] 7 is another schematic cross-sectional view showing a failure in the switching operation of the four-way switching valve 12 of FIG. 6. FIG. [Figure 8] FIG. 2 is a cross-sectional schematic view showing a four-way switching valve 12 that performs an oil discharge operation. [Figure 9] 4 is a flowchart of the switching control of the four-way switching valve 12. [Figure 10] 10 is a flowchart of an oil discharge operation. [Figure 11] 10 is a flowchart of an output process of a switching control signal Q2. DETAILED DESCRIPTION OF THE INVENTION

[0019] <Embodiment> (1) Overall structure The refrigeration device 100 shown in FIG. 1 is configured as, for example, an air conditioner, for providing a user with hot heat or cold heat obtained from a heat source. The refrigeration device 100 can perform a first refrigeration cycle and a second refrigeration cycle. In the first refrigeration cycle, a cold-heat utilization operation is performed to provide cold heat to the user. In the second refrigeration cycle, a hot-heat utilization operation is performed to provide hot heat to the user. If the refrigeration device 100 is an air conditioner, these correspond to a cooling operation and a heating operation, respectively.

[0020] The refrigeration device 100 has a heat source unit 10, a utilization unit 20, a connecting pipe 30, and a communication line 35. These components constitute a refrigerant circuit 90 that circulates the refrigerant R, and a control unit 9 that controls the refrigerant circuit 90.

[0021] Any refrigerant can be used as refrigerant R, and may be carbon dioxide, for example. In the following description, refrigerant R will be treated as being capable of undergoing a phase change to a liquid, and terms such as "condensation," "evaporation," "liquid refrigerant," and "gas-liquid two-phase refrigerant" will be used in the description. However, it should be noted that when refrigerant R is carbon dioxide, there is no phase change to a liquid, and therefore these terms do not strictly apply.

[0022] (1-1) Heat source unit 10 The heat source unit 10 obtains heat or cold from a heat source such as outdoor air. The heat source unit 10 has a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source expansion valve 15, an accumulator 16, a liquid shut-off valve 17, and a gas shut-off valve 18 as components of a refrigerant circuit 90. The heat source unit 10 also has a heat source fan 14 provided near the heat source heat exchanger 13. The heat source unit 10 further has a heat source control unit 19, which is a component of the control unit 9. The heat source unit 10 also has a low-pressure sensor S1, a high-pressure sensor S2, a heat source heat exchanger temperature sensor S3, and an outdoor air temperature sensor S4.

[0023] (1-1-1) Compressor 11 The compressor 11 has a suction pipe 11a and a discharge pipe 11b. The compressor 11 compresses low-pressure gas refrigerant drawn in through the suction pipe 11a, generates high-pressure gas refrigerant, and discharges it from the discharge pipe 11b. A low-pressure sensor S1 is provided on the suction side of the compressor 11, in other words, near the suction pipe 11a. A high-pressure sensor S2 is provided on the discharge side of the compressor 11, in other words, near the discharge pipe 11b. Both the low-pressure sensor S1 and the high-pressure sensor S2 measure the pressure of the refrigerant R.

[0024] (1-1-2) Four-way switching valve 12 The four-way switching valve 12 switches the circulation direction of the refrigerant R. The four-way switching valve 12 has a first port P1, a second port P2, a third port P3, and a fourth port P4. The first port P1 is connected to a pipe that communicates with the discharge pipe 11b. The second port P2 is connected to a pipe that communicates with the accumulator 16. The third port P3 is connected to a pipe that communicates with the heat source heat exchanger 13. The fourth port P4 is connected to a pipe that communicates with the gas shut-off valve 18.

[0025] When the refrigeration system 100 performs cold heat utilization operation, the four-way switching valve 12 connects the first port P1 to the third port P3 and also connects the second port P2 to the fourth port P4, as shown by the solid lines in Fig. 1. When the refrigeration system 100 performs hot heat utilization operation, the four-way switching valve 12 connects the first port P1 to the fourth port P4 and also connects the second port P2 to the third port P3, as shown by the dashed lines in Fig. 1.

[0026] (1-1-3) Heat source heat exchanger 13 The heat source heat exchanger 13 exchanges heat between the outdoor air and the refrigerant R. In cold heat utilization operation, the heat source heat exchanger 13 functions as a condenser or radiator of the refrigerant R, and in hot heat utilization operation, the heat source heat exchanger 13 functions as an evaporator or heat absorber of the refrigerant R. The heat source heat exchanger temperature sensor S3 provided near the heat source heat exchanger 13 measures the condensation temperature, evaporation temperature, and other temperatures of the refrigerant R in the heat source heat exchanger 13.

[0027] (1-1-4) Heat source fan 14 The heat source fan 14 moves the outdoor air through the heat source heat exchanger 13, thereby promoting heat exchange in the heat source heat exchanger 13. The temperature of the outdoor air is measured by the outdoor air temperature sensor S4.

[0028] (1-1-5) Heat source expansion valve 15 The heat source expansion valve 15 reduces the pressure of the refrigerant R and adjusts the flow rate of the refrigerant R.

[0029] (1-1-6) Accumulator 16 The accumulator 16 stores liquid refrigerant components mixed in the gas refrigerant and allows the gas refrigerant to pass through it. The accumulator 16 is connected to the suction pipe 11a of the compressor 11. The accumulator 16 prevents the liquid refrigerant from being sucked into the compressor 11.

[0030] (1-1-7) Liquid shutoff valve 17 The liquid stop valve 17 allows or blocks the passage of a liquid refrigerant or a gas-liquid two-phase refrigerant, etc. The liquid stop valve 17 is opened and closed manually by an installer of the refrigeration apparatus 100, for example.

[0031] (1-1-8) Gas shutoff valve 18 The gas shutoff valve 18 allows or blocks the passage of low-pressure gas refrigerant or high-pressure gas refrigerant. The gas shutoff valve 18 is opened and closed manually by, for example, an installer of the refrigeration device 100. (1-1-9) Heat source control unit 19 The heat source control unit 19 acquires measurement data from the low pressure sensor S1, the high pressure sensor S2, the heat source heat exchanger temperature sensor S3, and the outside air temperature sensor S4. The heat source control unit 19 also controls the compressor 11, the four-way switching valve 12, the heat source fan 14, and the heat source expansion valve 15.

[0032] (1-2) Usage unit 20 The utilization unit 20 provides hot or cold heat to a user. The utilization unit 20 has a utilization heat exchanger 23 as a component of a refrigerant circuit 90. The utilization unit 20 also has a utilization fan 24 provided near the utilization heat exchanger 23. The utilization unit 20 further has a utilization control unit 29 which is a component of the control unit 9. The utilization unit 20 further has a utilization heat exchanger temperature sensor S5 and a room temperature sensor S6. A remote controller 27 is connected to the utilization control unit 29 by wire or wirelessly.

[0033] (1-2-1) Utilized heat exchanger 23 The utilization heat exchanger 23 exchanges heat between the indoor air and the refrigerant R. In cold heat utilization operation, the utilization heat exchanger 23 functions as an evaporator or heat absorber of the refrigerant R, and in hot heat utilization operation, functions as a condenser or heat radiator of the refrigerant R. The utilization heat exchanger temperature sensor S5 provided near the utilization heat exchanger 23 measures the condensation temperature, evaporation temperature, and other temperatures of the refrigerant R in the utilization heat exchanger 23.

[0034] (1-2-2) 24 fans in use The utilization fan 24 moves the indoor air through the utilization heat exchanger 23, thereby promoting heat exchange in the utilization heat exchanger 23. The utilization fan 24 also sends the air conditioned by the utilization heat exchanger 23 to the vicinity of the user. The temperature of the indoor air is measured by the room temperature sensor S6.

[0035] (1-2-3) Usage Control Unit 29 The usage control unit 29 acquires measurement data from the usage heat exchanger temperature sensor S5 and the room temperature sensor S6. The usage control unit 29 also controls the usage fan 24. In addition, the usage control unit 29 communicates with the heat source control unit 19, thereby constituting the control unit 9 together with the heat source control unit 19. The usage control unit 29 further communicates with the remote controller 27.

[0036] (1-2-4) Remote Controller 27 The remote controller 27 receives commands from the user and presents information to the user. Commands from the user include setting a target temperature, setting an air volume, and also executing and switching between cold heat utilization operation and hot heat utilization operation.

[0037] (1-3) Connecting pipe 30 The communication pipe 30 connects the heat source unit 10 and the utilization unit 20 to form the refrigerant circuit 90. The communication pipe 30 has a liquid communication pipe 31 and a gas communication pipe 32.

[0038] (1-3-1) Liquid connection pipe 31 The liquid connection pipe 31 connects the liquid shutoff valve 17 and the utilization heat exchanger 23, and transfers liquid refrigerant or gas-liquid two-phase refrigerant.

[0039] (1-3-2) Gas connection pipe 32 The gas connection pipe 32 connects the gas shutoff valve 18 and the utilization heat exchanger 23, and transfers low-pressure gas refrigerant or high-pressure gas refrigerant.

[0040] (1-4) Communication line 35 The communication line 35 connects the heat source control unit 19 and the usage control unit 29 to form the control unit 9. The communication line 35 transmits control signals, status, data, and other signals between the heat source control unit 19 and the usage control unit 29.

[0041] (2) Configuration of four-way switching valve 12 2 shows a detailed configuration of the four-way switching valve 12. The four-way switching valve 12 has a main valve section 50, a pilot valve section 60, and a small diameter pipe group section 80.

[0042] (2-1) Main valve section 50 The main valve unit 50 determines the circulation direction of the refrigerant R. The main valve unit 50 includes a casing 51, a valve body 52, a first piston 53, and a second piston .

[0043] (2-1-1) Casing 51 The casing 51 is a cylindrical metal pipe. The internal space of the casing 51 forms a valve chamber 51a. Four pipes forming a first port P1, a second port P2, a third port P3, and a fourth port P4 are connected to the casing 51. Of these, the fourth port P4, the second port P2, and the third port P3 are aligned in this order in a row in the longitudinal direction of the casing 51. The first port P1 is located in a position that is not aligned with the rows of the other ports. The valve chamber 51a is filled with high-pressure gas refrigerant introduced from the first port P1.

[0044] (2-1-2) Valve body 52 The valve element 52 is a member that slides within the valve chamber 51a. The valve element 52 has an arch-shaped valve body 52a, a first connecting portion 52b extending in one direction from the valve body 52a, and a second connecting portion 52c extending from the valve body 52a in the opposite direction to the first connecting portion 52b. The valve element 52 is movable left and right in FIG. 2.

[0045] (2-1-3) First piston 53 The first piston 53 is fixed to the first connecting portion 52b and moves together with the valve body 52. ​​The first piston 53 forms a first pilot chamber 55 between the casing 51 and the left end of the valve chamber 51a. A first piston hole 53a with a small diameter is formed in the first piston 53. The first pilot chamber 55 communicates with the first port P1 via the first piston hole 53a.

[0046] (2-1-4) Second piston 54 The second piston 54 is fixed to the second connecting portion 52c and moves together with the valve body 52. ​​The second piston 54 forms a second pilot chamber 56 between itself and the casing 51 at the right end of the valve chamber 51a. A second piston hole 54a with a small diameter is formed in the second piston 54. The second pilot chamber 56 communicates with the second port P2 via the second piston hole 54a.

[0047] (2-2) Pilot valve section 60 The pilot valve unit 60 adjusts the pressure inside the first pilot chamber 55 and the second pilot chamber 56 by controlling the refrigerant R that moves to the first pilot chamber 55 and the second pilot chamber 56. The pilot valve unit 60 has a first pilot solenoid valve 61, a second pilot solenoid valve 62, and a connection unit 63.

[0048] (2-2-1) First pilot solenoid valve 61 The first pilot solenoid valve 61 controls whether or not the refrigerant R from the second port P2 reaches the first pilot chamber 55. The first pilot solenoid valve 61 has a first pilot valve body 71, a first cylinder 72, a first coil 73, and a first spring 74.

[0049] The first pilot valve element 71 is disposed in a first cylinder 72 and is movable left and right in FIG. 2. A first pilot valve 71a is formed at the right end of the first pilot valve element 71. The restoring force of a first spring 74 acts to move the first pilot valve element 71 to the right. When a current flows through the first coil 73, the first pilot valve element 71 is attracted to the first coil 73 against the restoring force of the first spring 74, thereby moving to the left.

[0050] (2-2-2) Second pilot solenoid valve 62 The second pilot solenoid valve 62 controls whether or not the refrigerant R from the second port P2 reaches the second pilot chamber 56. The second pilot solenoid valve 62 has a second pilot valve body 75, a second cylinder 76, a second coil 77, and a second spring 78.

[0051] The second pilot valve element 75 is disposed in a second cylinder 76 and is movable left and right in FIG. 2. A second pilot valve 75a is formed at the left end of the second pilot valve element 75. The restoring force of a second spring 78 acts to move the second pilot valve element 75 to the left. When a current flows through the second coil 77, the second pilot valve element 75 is attracted to the second coil 77 against the restoring force of the second spring 78, thereby moving to the right.

[0052] (2-2-3) Connection 63 The connecting part 63 is a member that connects the first pilot solenoid valve 61 and the second pilot solenoid valve 62. The connecting part 63 has a first pilot valve seat 65, a second pilot valve seat 66, a communication passage 64, a first connection port 67, a second connection port 68, and a third connection port 69.

[0053] The first pilot valve seat 65 receives the first pilot valve 71a. The first pilot valve seat 65 is in communication with a first connection port 67. Closing of the first pilot solenoid valve 61 means that the first pilot valve 71a comes into contact with the first pilot valve seat 65. At this time, the first connection port 67 is blocked by the first pilot valve 71a. Opening of the first pilot solenoid valve 61 means that the first pilot valve 71a moves away from the first pilot valve seat 65. At this time, the first connection port 67 is opened.

[0054] The second pilot valve seat 66 receives the second pilot valve 75a. The second pilot valve seat 66 is in communication with the second connection port 68. Closing of the second pilot solenoid valve 62 means that the second pilot valve 75a comes into contact with the second pilot valve seat 66. At this time, the second connection port 68 is blocked by the second pilot valve 75a. Opening of the second pilot solenoid valve 62 means that the second pilot valve 75a moves away from the second pilot valve seat 66. At this time, the second connection port 68 is opened.

[0055] The communication passage 64 connects the first pilot valve seat 65 and the second pilot valve seat 66. A third connection port 69 is formed in the communication passage 64. When the first pilot solenoid valve 61 opens, the first connection port 67 and the third connection port 69 communicate with each other via the communication passage 64. When the second pilot solenoid valve 62 opens, the second connection port 68 and the third connection port 69 communicate with each other via the communication passage 64.

[0056] (2-3) Thin-diameter tube group section 80 The small diameter tube group portion 80 is an assembly of capillary tubes and has a first flow path 81, a second flow path 82, and a third flow path 83. The first flow path 81 connects the first pilot chamber 55 and the first connection port 67. The second flow path 82 connects the second pilot chamber 56 and the second connection port 68. The third flow path 83 connects the second port P2 and the third connection port 69.

[0057] (3) Operation of the four-way switching valve 12 (3-1) Cold energy use operation status 2 shows the layout of the four-way valve 12 for cold energy utilization operation. The valve element 52 is located on the left side. As a result, the valve element 52 connects the second port with the fourth port and connects the first port with the third port.

[0058] To position the valve element 52 on the left side, the first pilot solenoid valve 61 is open and the second pilot solenoid valve 62 is closed. As a result, the second port P2 is in communication with the first pilot chamber 55 via the third flow path 83, the third connection port 69, the communication passage 64, the first connection port 67, and the first flow path 81. Because the pressure of the gas refrigerant present in the second port P2 is low, the refrigerant R in the first pilot chamber 55 can be drawn into the second port P2. Note that because the diameter of the first piston hole 53a is small, the refrigerant R on both sides of the first piston is not immediately equalized in pressure.

[0059] Because the second pilot solenoid valve 62 is closed, the second pilot chamber 56 is isolated from the second port P2. At this time, the second pilot chamber 56 is filled with high-pressure gas refrigerant that has flowed in from the second piston hole 54a.

[0060] A force acts on the valve element 52 to move it to the left due to the pressure difference between the low-pressure gas refrigerant in the first pilot chamber 55 and the high-pressure gas refrigerant in the second pilot chamber 56. This allows the valve element 52 to be stably positioned on the left side.

[0061] (3-2) Transient state 3 shows the transient state of the four-way switching valve 12 when switching from cold heat utilization operation to hot heat utilization operation. To switch the four-way switching valve 12, the first pilot solenoid valve 61 is closed and the second pilot solenoid valve 62 is opened. At this time, the second port P2 communicates with the second pilot chamber 56 via the third flow path 83, the third connection port 69, the communication passage 64, the second connection port 68, and the second flow path 82. The high-pressure gas refrigerant in the second pilot chamber 56 can be drawn into the second port P2.

[0062] Because the first pilot solenoid valve 61 is closed, the first pilot chamber 55 is isolated from the second port P2. At this time, the first pilot chamber 55 is filled with high-pressure gas refrigerant that has flowed in from the first piston hole 53a.

[0063] When the pressure of the gas refrigerant in the first pilot chamber 55 becomes greater than the pressure of the gas refrigerant in the second pilot chamber 56, a force acts to move the valve body 52 to the right.

[0064] (3-3) Heat utilization operation status Figure 4 shows the layout of the four-way valve during heat utilization operation. As in the transient state of Figure 3, the first pilot solenoid valve 61 is closed and the second pilot solenoid valve 62 is open. The valve element 52 located on the right side connects the second port with the third port and the first port with the fourth port.

[0065] A force acts on the valve element 52 to move it to the right due to the pressure difference between the high-pressure gas refrigerant in the first pilot chamber 55 and the low-pressure gas refrigerant in the second pilot chamber 56. This allows the valve element 52 to be stably positioned on the right side.

[0066] To resume cold energy utilization operation, the first pilot solenoid valve 61 is controlled to open and the second pilot solenoid valve 62 is controlled to close. This causes the first pilot chamber 55 to be filled with low-pressure gas refrigerant and the second pilot chamber 56 to be filled with high-pressure gas refrigerant, thereby generating a force that moves the valve element 52 to the left.

[0067] (4) Electrical system of the refrigeration device 100 5 shows the electrical system of the refrigeration apparatus 100. The control unit 9 receives measurement data from the low-pressure sensor S1, high-pressure sensor S2, heat-source heat exchanger temperature sensor S3, outside air temperature sensor S4, utilization heat exchanger temperature sensor S5, and room temperature sensor S6, as well as user commands transmitted from a remote controller 27. The control unit 9 also outputs control signals to the compressor 11, four-way switching valve 12, heat-source fan 14, heat-source expansion valve 15, and utilization fan 24.

[0068] The commands transmitted from the remote controller 27 include a switching command Q1 for the four-way selector valve 12. For example, if the user inputs to the remote controller 27 a command to perform a hot heat utilization operation while the refrigeration apparatus 100 is performing a cold heat utilization operation, the remote controller 27 transmits to the control unit 9 a switching command Q1 for switching the four-way selector valve 12 to perform the hot heat utilization operation. Alternatively, if the user inputs to the remote controller 27 a command to perform a cold heat utilization operation while the refrigeration apparatus 100 is performing a hot heat utilization operation, the remote controller 27 transmits to the control unit 9 a switching command Q1 for switching the four-way selector valve 12 to perform the cold heat utilization operation.

[0069] When the control unit 9 receives the switching command Q1, it performs a predetermined calculation to output a switching control signal Q2 for the four-way switching valve 12. Specifically, the switching control signal Q2 is an opening / closing control signal for the first pilot solenoid valve 61 and the second pilot solenoid valve 62.

[0070] (5) Oil discharge operation (5-1) Refrigerant oil blockage Fig. 6 shows a state in which refrigeration oil is trapped inside the four-way switching valve 12 during the cold energy utilization operation shown in Fig. 2. To position the valve body 52 to the left, the first pilot solenoid valve 61 is open and the second pilot solenoid valve 62 is closed. Refrigeration oil flows into the first flow path 81 and the first pilot chamber 55.

[0071] 6, the refrigeration oil also tends to enter, for example, the first piston hole 53a. In addition, if a resin seal is provided on the outer periphery of the first piston 53a, the refrigeration oil also tends to enter the gap between the outer periphery of the first piston 53a and the resin seal.

[0072] (5-2) Transient state during switching Figure 7 shows a transient state when the four-way selector valve 12 shown in Figure 6 switches from cold energy utilization operation to hot energy utilization operation. To switch the four-way selector valve 12, the first pilot solenoid valve 61 is closed and the second pilot solenoid valve 62 is open. The second port P2 communicates with the second pilot chamber 56 via the third flow path 83, the third connection port 69, the communication passage 64, the second connection port 68, and the second flow path 82. The high-pressure gas refrigerant in the second pilot chamber 56 can be drawn into the second port P2.

[0073] On the other hand, because the first pilot solenoid valve 61 is closed, refrigeration oil cannot pass through the first connection port 67. Therefore, refrigeration oil is not sucked out from the second port P2. Because the first pilot chamber 55 is not filled with refrigerant, the high-pressure gas refrigerant in the valve chamber 51a cannot enter the first pilot chamber 55 through the first piston hole 53a. In addition, because the refrigeration oil filling the first pilot chamber 55 is liquid, it cannot expand even when an external force is applied. Therefore, the first piston 53 cannot move to the right, and neither can the valve element 52. In this way, the switching operation of the four-way selector valve 12 is inhibited by the refrigeration oil.

[0074] (5-3) Details of oil discharge operation When the four-way switching valve 12 cannot perform the switching operation due to refrigeration oil, or when it is predicted that the switching operation will not be possible, the control unit 9 performs the oil discharge operation. Figure 8 shows the four-way switching valve 12 when the oil discharge operation is being performed.

[0075] In the oil discharge operation, the control unit 9 operates the compressor 11 to supply high-pressure gas refrigerant to the four-way switching valve 12. Furthermore, the control unit 9 keeps both the first pilot solenoid valve 61 and the second pilot solenoid valve 62 open for a predetermined time. The predetermined time is, for example, five seconds.

[0076] The refrigeration oil that has been clogged in the first pilot chamber 55 and the first flow path 81 is sucked into the suction pipe 11a of the compressor 11 via the first connection port 67, the communication passage 64, the third flow path 83, and the second port P2. The refrigerant R that fills the second pilot chamber 56 is also sucked into the suction pipe 11a of the compressor 11 via the second flow path 82, the second connection port 68, the communication passage 64, the third flow path 83, and the second port P2.

[0077] By the above oil discharge operation, refrigeration oil remaining in the valve chamber 51a, the first flow path 81, or the second flow path 82 can be discharged to the outside of the four-way switching valve 12. To promote the discharge of refrigeration oil, the four-way switching valve 12 may be arranged so that the second port P2 faces downward.

[0078] Thereafter, in order to switch to the heat utilization operation, the control unit 9 performs control to close the first pilot solenoid valve 61 while keeping the second pilot solenoid valve 62 open, thereby bringing the four-way switching valve 12 into the state shown in FIG.

[0079] (6) Switching control of four-way switching valve 12 9 is a flowchart of a main routine for switching control of the four-way switching valve 12. In step S100, switching control is started. In step S101, the control unit 9 checks whether a switching command Q1 issued from the remote controller 27 in response to a user input has already been received. If the switching command Q1 has not yet been received (S101: NO), the process returns to step S101. If the switching command Q1 has already been received (S101: YES), the process proceeds to step S102.

[0080] In step S102, the control unit 9 checks whether the pressure difference, which is the difference between the measurement value of the low pressure sensor S1 and the measurement value of the high pressure sensor S2, is smaller than a predetermined value. If the measured pressure difference is smaller than the predetermined value (S102: YES), the process proceeds to step S103. If the measured pressure difference is not smaller than the predetermined value (S102: NO), the process proceeds to step S104.

[0081] In step S103, a subroutine for the oil discharge operation is executed. The subroutine for the oil discharge operation will be described later. When the oil discharge operation is completed, the process proceeds to step S104.

[0082] In step S104, the control unit 9 executes a subroutine for outputting a switching control signal Q2 to the four-way switching valve 12. The subroutine for outputting the switching control signal Q2 will be described later.

[0083] Thereafter, in step S105, the switching control of the four-way switching valve 12 ends.

[0084] FIG. 10 is a flowchart of the oil discharge operation subroutine. In step S200, the oil discharge operation is started. In step S201, the control unit 9 checks whether the compressor 11 is operating. If the compressor 11 is operating (S201: YES), the process proceeds to step S203. On the other hand, if the compressor 11 is not operating (S201: NO), the process proceeds to step S202. In step S202, the operation of the compressor 11 is started. As a result, high-pressure gas refrigerant is supplied from the discharge pipe 11b.

[0085] In step S203, the control unit 9 opens both the first pilot solenoid valve 61 and the second pilot solenoid valve 62. In step S204, the count value of the timer of the control unit 9 is reset to zero. In step S205, the control unit 9 starts timing the timer. In step S206, the control unit 9 references the count value of the timer and checks whether a predetermined time has elapsed. The predetermined time is, for example, 5 seconds. If the predetermined time has not elapsed (S206: NO), the process returns to step S206. On the other hand, if the predetermined time has elapsed (S206: YES), the process proceeds to step S207. In step S207, the control unit 9 ends timing the timer. In step S208, the oil discharge operation subroutine ends.

[0086] 11 is a flowchart of a subroutine for processing the output of the switching control signal Q2. In step S300, output of the switching control signal Q2 begins. In step S301, the control unit 9 checks the content of the switching command Q1 that it has already received. If the content of the switching command Q1 requests execution of cold energy utilization operation (step S301: cold energy utilization operation), the process proceeds to step S302. In step S302, the control unit 9 outputs a switching control signal Q2 that opens the first pilot solenoid valve 61 and closes the second pilot solenoid valve 62. Thereafter, in step S304, the process for outputting the switching control signal Q2 ends.

[0087] On the other hand, if the content of the switching command Q1 requests execution of the heat utilization operation (step S301: heat utilization operation), the process proceeds to step S303. In step S303, the control unit 9 outputs a switching control signal Q2 to close the first pilot solenoid valve 61 and open the second pilot solenoid valve 62. Thereafter, in step S304, the process of outputting the switching control signal Q2 ends.

[0088] (7) Features (7-1) Before the switching operation of the four-way switching valve 12, the oil discharge operation discharges the refrigeration oil inside the four-way switching valve 12. Therefore, the risk of the switching of the four-way switching valve 12 failing due to the refrigeration oil remaining inside the four-way switching valve 12 can be reduced.

[0089] (7-2) The state in which the pressure difference between the refrigerant R on the suction side and the discharge side of the compressor 11 is smaller than a predetermined value, as confirmed in step S102, is the result of a failure in switching the four-way switching valve 12. When the switching of the four-way switching valve 12 fails, an oil discharge operation is performed. Therefore, the four-way switching valve 12 is likely to be successfully switched again.

[0090] (7-3) In the oil discharge operation, refrigeration oil is discharged from the first flow path 81 or the second flow path 82 by opening both the first pilot solenoid valve 61 and the second pilot solenoid valve 62. Therefore, the refrigeration oil that has entered the first pilot chamber 55 or the second pilot chamber 56 is less likely to hinder the movement of the valve body 52.

[0091] (7-4) In the oil discharge operation, both the first pilot solenoid valve 61 and the second pilot solenoid valve 62 are continuously opened. Therefore, refrigeration oil remaining in the first flow path 81 or the second flow path 82 is continuously sucked by the compressor 11.

[0092] (7-5) After the oil discharge operation is completed, in step S302 or step S303, one of the first pilot solenoid valve 61 and the second pilot solenoid valve 62 is closed, so that the four-way switching valve 12 is switched appropriately.

[0093] (7-6) The four-way switching valve 12 is disposed so that the second port P2 faces downward, thereby facilitating the discharge of refrigeration oil during the oil discharge operation.

[0094] (8) Variations (8-1) First Modification In the above-described embodiment, during the oil discharging operation, the control unit 9 continues to open both the first pilot solenoid valve 61 and the second pilot solenoid valve 62. Alternatively, during the oil discharging operation, the control unit 9 may repeatedly open and close the first pilot solenoid valve 61 for a predetermined time while continuing to open the second pilot solenoid valve 62. Alternatively, the control unit 9 may repeatedly open and close both the first pilot solenoid valve 61 and the second pilot solenoid valve 62 for a predetermined time.

[0095] According to this configuration, during the oil discharge operation, the first pilot solenoid valve 61 is repeatedly opened and closed to encourage the movement of refrigeration oil in the first flow path 81.

[0096] To cope with clogging of the second flow path 82 with refrigeration oil, the control unit 9 may repeatedly open and close the second pilot solenoid valve 62 for a predetermined time while keeping the first pilot solenoid valve 62 open.

[0097] (8-2) Second Modification In the above-described embodiment, the switching command Q1 is issued by the remote controller 27. Alternatively, the switching command Q1 may be issued by another component. For example, the switching command Q1 can be issued using the output of the heat source heat exchanger temperature sensor S3 as a trigger. When the control unit 9 recognizes from the measurement value of the heat source heat exchanger temperature sensor S3 that condensation has formed on the heat source heat exchanger 13 while the refrigeration apparatus 100 is performing a hot heat utilization operation, the control unit 9 can perform a defrost operation by issuing a switching control signal Q2 to the four-way switching valve 12 to execute a cold heat utilization operation.

[0098] (8-3) Third Modification In the above-described embodiment, in the oil discharge operation shown in Fig. 10, the operation of the compressor 11 in step S202 is not particularly different from normal operation. Alternatively, in the oil discharge operation, the operation of the compressor 11 may be changed from normal operation. For example, in the oil discharge operation, the rotation speed of the compressor 11 may be reduced to a predetermined small value or increased to a predetermined large value.

[0099] (8-4) Fourth Modification In the above-described embodiment, in step S102 of Fig. 9, it is confirmed whether or not the switching of the four-way switching valve 12 has failed. When a state in which the pressure difference between the refrigerant R on the suction side and the discharge side of the compressor 11 is detected to be smaller than a predetermined value, it is determined that the switching of the four-way switching valve 12 has failed. Alternatively, the failure of the switching of the four-way switching valve 12 may be confirmed by detecting another phenomenon.

[0100] For example, after the control unit 9 receives a switching command Q1 requesting the execution of cold energy utilization operation in step S101, if the heat source heat exchanger temperature sensor S3 detects a value lower than a predetermined temperature in step S102, the control unit 9 may determine that the switching of the four-way switching valve 12 has failed.

[0101] Alternatively, after the control unit 9 receives a switching command Q1 requesting the execution of cold energy utilization operation in step S101, if the utilization heat exchanger temperature sensor S5 detects a value higher than a predetermined temperature in step S102, the control unit 9 may determine that the switching of the four-way switching valve 12 has failed.

[0102] Alternatively, after the control unit 9 receives a switching command Q1 requesting the execution of heat utilization operation in step S101, if the heat source heat exchanger temperature sensor S3 detects a value higher than a predetermined temperature in step S102, the control unit 9 may determine that the switching of the four-way switching valve 12 has failed.

[0103] Alternatively, after the control unit 9 receives a switching command Q1 requesting the execution of heat utilization operation in step S101, if the utilization heat exchanger temperature sensor S5 detects a value lower than a predetermined temperature in step S102, the control unit 9 may determine that the switching of the four-way switching valve 12 has failed.

[0104] When it is confirmed that the switching of the four-way switching valve 12 has failed (S102: YES), the oil discharge operation is executed in step S103.

[0105] <Conclusion> Although the embodiments of the present disclosure 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 present disclosure as defined in the claims. [Explanation of symbols]

[0106] 9: Control section 10: Heat source unit 11: Compressor 12: Four-way switching valve 13:Heat source heat exchanger 15: Heat source expansion valve 19: Heat source control unit 20: Usage unit 23: Utilization heat exchanger 27: Remote controller 29: Usage control section 30: Connecting piping 50: Main valve section 51: Casing 51a: Valve chamber 52: Valve body 53: First piston 54: Second piston 55: First Pilot Room 56: Second pilot room 60: Pilot valve section 61: First pilot solenoid valve 62: Second pilot solenoid valve 64:Communication path 80: Small diameter tube group section 81: First flow path 82: Second flow path 83: Third flow path 90: Refrigerant circuit 100: Refrigeration equipment P1: First port P2: Second port P3: Third port P4: 4th port Q1: Switching command Q2: Switching control signal R: Refrigerant S1: Low pressure sensor S2: High pressure sensor [Prior art documents] [Patent documents]

[0107] [Patent Document 1] Japanese Patent Application Publication No. 63-015056

Claims

1. a compressor (11) for compressing a refrigerant (R); A four-way switching valve (12); a heat source heat exchanger (13); a utilization heat exchanger (23); A control unit (9); Equipped with the four-way switching valve switches between a first refrigeration cycle in which the heat source heat exchanger functions as a radiator and the utilization heat exchanger functions as a heat absorber, and a second refrigeration cycle in which the heat source heat exchanger functions as a heat absorber and the utilization heat exchanger functions as a radiator, The control unit performs an oil discharge operation to discharge refrigeration oil remaining inside the four-way switching valve to the outside of the four-way switching valve before the switching of the four-way switching valve. A refrigeration device (100).

2. The control unit performs the oil discharge operation when a pressure difference between the refrigerant on the suction side and the discharge side of the compressor is smaller than a predetermined value. The refrigeration system of claim 1.

3. The four-way switching valve is A valve chamber (51); a valve body (52) that slides in the valve chamber; a first pilot chamber (55) formed at an end of the valve chamber; a second pilot chamber (56) formed at an end of the valve chamber opposite to the first pilot chamber; a first port (P1) formed in the valve chest for receiving the refrigerant discharged from the compressor, a second port (P2) for ejecting the refrigerant drawn into the compressor, a third port (P3) for transferring the refrigerant between the heat source heat exchanger and the valve chest, and a fourth port (P4) for transferring the refrigerant between the heat utilization heat exchanger and the valve chest; a first pilot solenoid valve (61); a second pilot solenoid valve (62); a communication passage (64) that communicates the first pilot solenoid valve and the second pilot solenoid valve; a first flow path (81) that communicates the first pilot chamber with the communication path when the first pilot solenoid valve is open; a second flow path (82) that communicates the second pilot chamber with the communication path when the second pilot solenoid valve is open; a third flow path (83) that connects the communication path and the second port; and When performing the oil discharge operation, the control unit operates the compressor and opens both the first pilot solenoid valve and the second pilot solenoid valve, thereby discharging the refrigeration oil remaining in the valve chamber, the first flow path, or the second flow path to the outside of the four-way selector valve. The refrigeration device according to claim 1 or 2.

4. During the oil discharge operation, the control unit continues to open both the first pilot solenoid valve and the second pilot solenoid valve.

4. The refrigeration system of claim 3.

5. In the oil discharging operation, the control unit repeatedly opens and closes at least one of the first pilot solenoid valve and the second pilot solenoid valve.

4. The refrigeration system of claim 3.

6. After the oil discharging operation continues for a predetermined time, the control unit closes either the first pilot solenoid valve or the second pilot solenoid valve.

4. The refrigeration system of claim 3.

7. The four-way switching valve is arranged so that the second port faces downward.

4. The refrigeration system of claim 3.

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