Refrigerating device having four-way switching valve and shut-off valve

Abstract

To restrain breakage of a four-way switching valve at the time of switching the four-way switching valve due to a pressure difference from a high-pressure gas refrigerant emitted from a compressor.SOLUTION: A refrigerating device 100 comprises a refrigerant circuit 90, a control part 9 and a first shut-off valve 41. The refrigerant circuit 90 has a compressor 11, a four-way switching valve 12, a heat source heat-exchanger 13, and a utilization heat-exchanger 23. The compressor 11 has a suction port 11a for sucking a refrigerant R, and an emission port 11b for emitting the refrigerant. The control part 9 switches a circulation path of the refrigerant R in the refrigerant circuit 90 by switching the four-way switching valve 12. The first shut-off valve 41 is arranged between the four-way switching valve 12 and the utilization heat-exchanger 23. The control part 9 closes the first shut-off valve 41 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 and a shut-off valve. [Background technology]

[0002] The four-way switching valve disclosed in Patent Document 1 (Japanese Patent Laid-Open Publication No. 63-015056) is mounted in a refrigeration device for the purpose of switching the circulation direction of a refrigerant. Summary of the Invention [Problem to be solved by the invention]

[0003] Some refrigerants used in refrigeration systems have a large pressure difference between the low-pressure gas refrigerant drawn into the compressor and the high-pressure gas refrigerant discharged from the compressor. Such a large pressure difference can cause shocks when switching the four-way selector valve, potentially damaging the valve. [Means for solving the problem]

[0004] A refrigeration device according to a first aspect includes a refrigerant circuit, a control unit, and a first shutoff valve. The refrigerant circuit has a compressor, a four-way switching valve, a heat source heat exchanger, and a utilization heat exchanger. The compressor has an intake port for drawing in refrigerant and an outlet port for discharging refrigerant. The control unit switches the circulation path of the refrigerant in the refrigerant circuit by switching the four-way switching valve. The first shutoff valve is disposed between the four-way switching valve and the utilization heat exchanger. The control unit closes the first shutoff valve before switching the four-way switching valve.

[0005] According to this configuration, the refrigerant circuit around the four-way switching valve is shut off by closing the first shutoff valve before switching the four-way switching valve, thereby reducing damage to the four-way switching valve caused by a pressure difference between large amounts of refrigerant.

[0006] A refrigeration apparatus according to a second aspect is the refrigeration apparatus according to the first aspect, further comprising a second shutoff valve. The second shutoff valve is disposed between the four-way selector valve and the heat source heat exchanger. The control unit further closes the second shutoff valve before switching the four-way selector valve.

[0007] With this configuration, not only the first shutoff valve but also the second shutoff valve contributes to shutting off the refrigerant circuit around the four-way selector valve, thereby further reducing damage to the four-way selector valve.

[0008] A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the second aspect, further comprising a bypass flow path and a pressure equalizing valve. The bypass flow path connects the suction port and the discharge port. The pressure equalizing valve is configured to open or close the bypass flow path. The control unit further opens the pressure equalizing valve before performing the switching.

[0009] With this configuration, the open pressure equalizing valve reduces the pressure difference between the refrigerant at the suction port and the discharge port, thereby further reducing damage to the four-way selector valve.

[0010] A refrigeration device according to a fourth aspect is a refrigeration device according to any one of the first aspect to the third aspect, in which the control unit switches the four-way switching valve after a predetermined time has elapsed after receiving a switching command for the four-way switching valve.

[0011] With this configuration, it is expected that the pressure difference between the refrigerant at the suction port and the discharge port will be eliminated after a predetermined time has passed, thereby reducing damage to the four-way selector valve.

[0012] A refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to any one of the first aspect to the fourth aspect, wherein the control unit stops the compressor after receiving a switching command for the four-way switching valve.

[0013] With this configuration, the compressor is stopped when switching, thereby preventing a pressure difference between the refrigerant at the suction port and the discharge port.

[0014] A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to the third aspect, wherein the control unit closes the first shutoff valve or the second shutoff valve and opens the pressure equalizing valve before switching the four-way switching valve. The control unit switches the four-way switching valve with the pressure equalizing valve open. After switching the four-way switching valve, the control unit closes the pressure equalizing valve and opens the first shutoff valve or the second shutoff valve.

[0015] According to this configuration, the pressure equalizing valve is opened before the four-way selector valve is switched, thereby eliminating the pressure difference between the refrigerant at the suction port and the discharge port, thereby suppressing damage to the four-way selector valve.

[0016] A refrigeration system according to a seventh aspect is the refrigeration system according to the third aspect, wherein the control unit closes the first shutoff valve or the second shutoff valve and opens the pressure equalizing valve before switching the four-way switching valve. The control unit closes the pressure equalizing valve when the pressure difference between the suction port and the discharge port becomes equal to or less than a predetermined value. The control unit switches the four-way switching valve with the pressure equalizing valve closed. After switching the four-way switching valve, the control unit opens the first shutoff valve or the second shutoff valve.

[0017] With this configuration, the pressure equalizing valve is closed before the four-way selector valve is switched, so that if it is determined that the pressure difference between the refrigerant at the suction port and the discharge port is sufficiently small, the pressure equalizing valve can be quickly closed.

[0018] A refrigeration apparatus according to an eighth aspect is the refrigeration apparatus according to any one of the first aspect to the seventh aspect, wherein the refrigerant is carbon dioxide.

[0019] In this configuration, the refrigerant is carbon dioxide. When carbon dioxide is used as the refrigerant, the four-way valve tends to make a loud noise when switching. Therefore, by operating the first shutoff valve, etc., the shock generated when switching is less likely to be transmitted to the outside.

[0020] A refrigeration apparatus according to a ninth aspect is the refrigeration apparatus according to the second or third aspect, further comprising a heat source unit, a utilization unit, and a valve unit. The heat source unit has a compressor, a four-way switching valve, and a heat source heat exchanger. The utilization unit has a utilization heat exchanger. The valve unit is disposed between the heat source unit and the utilization unit. The first shut-off valve or the second shut-off valve is disposed in the valve unit.

[0021] According to this configuration, the first and second shutoff valves are disposed in the valve unit, and therefore, when the first and second shutoff valves are provided, there is no need to change the design of the refrigerant circuit of the heat source unit. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a circuit diagram showing the configuration of a refrigeration device 100 according to a first embodiment. [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] 4 is a flowchart of the switching control of the four-way switching valve 12. [Figure 7] 10 is a flowchart of an output process of a switching control signal Q2. [Figure 8] 10 is a flowchart of switching control of the four-way switching valve 12 according to a second modified example of the first embodiment. [Figure 9] 1 is a cross-sectional view showing the structure of a rotary four-way switching valve 12. FIG. [Figure 10] 10 is a flowchart of switching control of the four-way switching valve 12 according to a third modified example of the first embodiment. [Figure 11] FIG. 10 is a circuit diagram showing the configuration of a refrigeration device 100 according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] First Embodiment (1) Overall structure FIG. 1 shows a refrigeration apparatus 100 according to a first embodiment. The refrigeration apparatus 100 is configured as, for example, an air conditioner, and is used to provide a user with hot heat or cold heat obtained from a heat source. The refrigeration apparatus 100 can perform a cold-heat utilization operation to provide cold heat to a user, and a hot-heat utilization operation to provide hot heat to a user. If the refrigeration apparatus 100 is an air conditioner, these operations correspond to cooling operation and heating operation, respectively.

[0024] The refrigeration device 100 has a heat source unit 10, a plurality of utilization units 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.

[0025] 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.

[0026] (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, as components of a refrigerant circuit 90, 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, a gas shut-off valve 18, a first shut-off valve 41, a second shut-off valve 42, and a pressure equalizing valve 43. 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 and a high-pressure sensor S2.

[0027] (1-1-1) Compressor 11 The compressor 11 has a suction port 11a and a discharge port 11b. The compressor 11 compresses low-pressure gas refrigerant drawn in through the suction port 11a to generate high-pressure gas refrigerant, which is discharged from the discharge port 11b. A low-pressure sensor S1 is provided on the suction side of the compressor 11, in other words, near the suction port 11a. A high-pressure sensor S2 is provided on the discharge side of the compressor 11, in other words, near the discharge port 11b. Both the low-pressure sensor S1 and the high-pressure sensor S2 measure the pressure of the refrigerant R.

[0028] (1-1-2) Four-way switching valve 12 The four-way switching valve 12 switches the circulation path 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 port 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.

[0029] 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.

[0030] (1-1-3) Heat source heat exchanger 13 The heat source heat exchanger 13 exchanges heat between the outdoor air and the refrigerant R. The heat source heat exchanger 13 functions as a condenser or a radiator of the refrigerant R in the cold heat utilization operation, and functions as an evaporator or a heat absorber of the refrigerant R in the hot heat utilization operation.

[0031] (1-1-4) Heat source fan 14 The heat source fan 14 moves the outdoor air and passes it through the heat source heat exchanger 13, thereby promoting heat exchange in the heat source heat exchanger 13.

[0032] (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.

[0033] (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 port 11a of the compressor 11. The accumulator 16 prevents the liquid refrigerant from being drawn into the compressor 11.

[0034] (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.

[0035] (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) First shutoff valve 41 The first shutoff valve 41 passes or blocks the refrigerant R under the control of the control unit 9. The first shutoff valve 41 is disposed between the four-way switching valve 12 and a utilization heat exchanger 23, which will be described later. Specifically, the first shutoff valve 41 is disposed between the fourth port P4 of the four-way switching valve 12 and the gas stop valve 18.

[0036] (1-1-10) Second shutoff valve 42 The second shutoff valve 42 passes or blocks the refrigerant R under the control of the control unit 9. The second shutoff valve 42 is disposed between the third port P3 of the four-way switching valve 12 and the heat source heat exchanger 13.

[0037] (1-1-11) Pressure equalization valve 43 The pressure equalizing valve 43 allows or blocks the passage of the refrigerant R under the control of the control unit 9. The pressure equalizing valve 43 is disposed in a bypass flow path 95 that connects the suction port 11a and the discharge port 11b and bypasses the compressor 11. When the pressure equalizing valve 43 opens, it reduces the pressure difference of the refrigerant between the suction port 11a and the discharge port 11b.

[0038] (1-1-12) Heat source control unit 19 The heat source control unit 19 acquires measurement data from the low pressure sensor S1 and the high pressure sensor S2. The heat source control unit 19 also controls the compressor 11, the four-way switching valve 12, the heat source fan 14, the heat source expansion valve 15, the first shutoff valve 41, the second shutoff valve 42, and the pressure equalizing valve 43.

[0039] (1-2) Usage unit 20 The multiple utilization units 20 generally have the same configuration. One of the multiple utilization units 20 will be described below.

[0040] The utilization unit 20 provides hot or cold heat to a user. The utilization unit 20 has a utilization expansion valve 22 and a utilization heat exchanger 23 as components 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. A remote controller 27 is connected to the utilization control unit 29 by wire or wirelessly.

[0041] (1-2-1) Use expansion valve 22 The utilization expansion valve 22 reduces the pressure of the refrigerant R and adjusts the flow rate of the refrigerant R.

[0042] (1-2-2) Utilized heat exchanger 23 The utilization heat exchanger 23 exchanges heat between the indoor air and the refrigerant R. The utilization heat exchanger 23 functions as an evaporator or heat absorber of the refrigerant R in the cold heat utilization operation, and functions as a condenser or heat radiator of the refrigerant R in the hot heat utilization operation.

[0043] (1-2-3) 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.

[0044] (1-2-4) Usage Control Unit 29 The usage control unit 29 acquires measurement data from a sensor (not shown). The usage control unit 29 also controls the usage expansion valve 22 and 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.

[0045] (1-2-5) 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.

[0046] (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.

[0047] (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.

[0048] (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.

[0049] (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.

[0050] (2) Configuration of four-way switching valve 12 2 shows the detailed configuration of the four-way switching valve 12. The four-way switching valve 12 is a differential pressure driven type. 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.

[0051] (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 .

[0052] (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.

[0053] (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.

[0054] (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.

[0055] (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.

[0056] (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.

[0057] (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.

[0058] 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.

[0059] (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.

[0060] 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.

[0061] (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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] (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.

[0066] (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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] (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.

[0071] 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.

[0072] 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.

[0073] (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.

[0074] 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.

[0075] 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.

[0076] (4) Control of four-way switching valve 12 (4-1) 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 and the high-pressure sensor S2, as well as user commands transmitted from the respective remote controllers 27 of the multiple utilization units 20. The control unit 9 also outputs control signals to the compressor 11, the four-way switching valve 12, the heat-source fan 14, the heat-source expansion valve 15, and the utilization expansion valves 22 and utilization fans 24 belonging to each of the multiple utilization units 20.

[0077] 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.

[0078] 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.

[0079] (4-2) Switching control 6 is a flowchart of a main routine for switching control of the four-way switching valve 12. In step S100, switching control starts.

[0080] In step S101, it is confirmed whether the refrigerant circuit 90 is in a normal state, in which the first shutoff valve 41 and the second shutoff valve 42 are open and the equalizing valve 43 is closed. If the normal state is not achieved (S101: NO), the process proceeds to error processing in step S191. On the other hand, if the normal state is achieved (S101: YES), the process proceeds to step S102.

[0081] In step S102, it is confirmed whether the control unit 9 has received the switching command Q1. If the switching command Q1 has not been received (S102: NO), the process proceeds to error processing in step S191. On the other hand, if the switching command Q1 has been received (S102: YES), the process proceeds to step S103.

[0082] In step S103, the control unit 9 stops the compressor 11. In step S104, the control unit 9 closes the first shutoff valve 41 and the second shutoff valve 42, and opens the equalizing valve 43. This prepares the refrigerant circuit 90 for switching the four-way switching valve 12.

[0083] In step S111, the count value of the timer of the control unit 9 is reset to zero. In step S112, the control unit 9 starts timing the timer. In step S113, 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, five seconds. If the predetermined time has not elapsed (S113: NO), the process returns to step S113. On the other hand, if the predetermined time has elapsed (S113: YES), the process proceeds to step S114. In step S114, the control unit 9 ends timing the timer. As a result, the predetermined time has elapsed since the refrigerant circuit 90 was prepared to switch the four-way switching valve 12, and the state of the refrigerant R is expected to stabilize.

[0084] In step S121, the control unit 9 closes the pressure equalizing valve 43.

[0085] In step S131, 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.

[0086] After the switching control of the four-way switching valve 12 is completed, in step S141, the control unit 9 opens the first shutoff valve 41 and the second shutoff valve 42 to restore the connections of the refrigerant circuit 90 other than the four-way switching valve 12. Next, in step S142, the control unit 9 restarts the operation of the compressor 11.

[0087] Thereafter, in step S114, the main routine for controlling the switching of the four-way switching valve 12 ends.

[0088] Step S191 is error processing. In this step, the control unit 9 returns the refrigerant circuit 90 to a normal state by opening the first shutoff valve 41 and the second shutoff valve and closing the equalizing valve 43. In step S192, the control unit 9 ends the main routine of the switching control due to an error.

[0089] 7 is a flowchart of a subroutine for processing to output the switching control signal Q2. In step S200, output of the switching control signal Q2 begins. In step S201, 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 S201: cold energy utilization operation), the process proceeds to step S202. In step S202, the control unit 9 outputs a switching control signal Q2 to open the first pilot solenoid valve 61 and close the second pilot solenoid valve 62. Thereafter, in step S204, the process to output the switching control signal Q2 ends.

[0090] On the other hand, if the content of the switching command Q1 requests execution of the heat utilization operation (step S201: heat utilization operation), the process proceeds to step S203. In step S203, 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 S204, the process of outputting the switching control signal Q2 ends.

[0091] (5) Features (5-1) By closing the first shutoff valve 41 and the second shutoff valve 42 before switching the four-way switching valve 12, the refrigerant circuit 90 around the four-way switching valve 12 is shut off. Therefore, damage to the four-way switching valve 12 due to a pressure difference of a large amount of refrigerant R can be reduced.

[0092] (5-2) By opening the pressure equalizing valve 43, the pressure difference of the refrigerant R between the suction port 11a and the discharge port 11b is reduced, and therefore damage to the four-way switching valve 12 can be further reduced.

[0093] (5-3) After receiving the switching command Q1 for the four-way switching valve, the control unit 9 waits a predetermined time before switching the four-way switching valve 12. Therefore, after the predetermined time has passed, the pressure difference of the refrigerant R between the suction port 11a and the discharge port 11b is expected to be eliminated, thereby reducing damage to the four-way switching valve 12.

[0094] (5-4) After receiving the switching command Q1 for the four-way switching valve 12, the control unit 9 stops the compressor 11 in step S103. This makes it possible to avoid the pressure difference of the refrigerant R between the suction port 11a and the discharge port 11b from being generated.

[0095] (5-5) Before switching the four-way switching valve 12 in step S131, the pressure equalizing valve 43 is closed in step S121. Therefore, if it is determined that the pressure difference of the refrigerant R between the suction port 11a and the discharge port 11b is sufficiently small, the pressure equalizing valve 43 can be quickly closed.

[0096] In particular, when the four-way switching valve 12 is a differential pressure driven type as shown in Figures 2 to 4, once the pressure difference has been reduced to a certain extent by pressure equalization, the pressure equalization valve 43 can be closed even before the four-way switching valve 12 is switched.

[0097] (5-6) The refrigerant R may be carbon dioxide. When carbon dioxide is used as the refrigerant, the switching noise of the four-way switching valve 12 tends to be loud. Therefore, by closing the first shutoff valve 41 and the second shutoff valve 42, the shock generated when the four-way switching valve 12 switches is less likely to be transmitted to the outside.

[0098] (6) Variations (6-1) First Modification In the above-described embodiment, the control unit 9 closes both the first shutoff valve 41 and the second shutoff valve 42 before the switching operation of the four-way switching valve 12. Alternatively, the control unit 9 may close either the first shutoff valve 41 or the second shutoff valve 42 before the switching operation of the four-way switching valve 12.

[0099] (6-2) Second Modification 6, in the above-described embodiment, the control unit 9 waits a predetermined time after receiving a switching command Q1 for the four-way switching valve 12 before switching the four-way switching valve 12. Alternatively, after receiving the switching command Q1 for the four-way switching valve 12, the control unit 9 may calculate the pressure difference between the refrigerant R on the suction side and the discharge side of the compressor 11 from the measured values ​​of the low pressure sensor S1 and the high pressure sensor S2, and switch the four-way switching valve 12 after confirming that the pressure difference is small.

[0100] FIG. 8 is a flowchart of a main routine for controlling the switching of the four-way switching valve 12 according to the second modification. In step S302, the control unit 9 confirms that it has received the switching command Q1. Then, in step S304, the control unit 9 opens the equalizing valve 43. In step S313, the control unit 9 calculates the pressure difference between the high-pressure side and the low-pressure side from the measured values ​​of the low-pressure sensor S1 and the high-pressure sensor S2, and checks whether the pressure difference is smaller than a predetermined value. If the predetermined time has elapsed (S314: YES) while the pressure difference is not smaller than the predetermined value (S313: NO), the process proceeds to error processing in step S391. On the other hand, if the pressure difference is smaller than the predetermined value (S313: YES), the process proceeds to step S331 via steps S316 and S321. In step S331, the four-way switching valve 12 is switched.

[0101] (6-3) Third Modification In the above-described embodiment, the four-way switching valve 12 is of a differential pressure drive type as shown in Figures 2 to 4. Alternatively, the four-way switching valve 12 may be of a rotary type.

[0102] The rotary four-way selector valve 12 shown in FIG. 9 has a cylindrical casing 251 and a valve seat 255 provided on the bottom surface of the casing 251. The valve seat 255 is provided with a first port P1, a second port P2, a third port P3, and a fourth port P4 through which the refrigerant R passes. A cylindrical valve element 252 is rotatably disposed within the casing 251. The valve element 252 is provided with a high-pressure groove 252a and a low-pressure groove 252b. The valve element 252 can rotate 90° due to the action of a coil and a permanent magnet (not shown). In FIG. 9, the first port P1 and the third port P3 are communicated with each other, and the second port P2 and the fourth port P4 are communicated with each other. When the valve element 252 is rotated 90° from the state shown in FIG. 9, the first port P1 and the fourth port P4 are communicated with each other, and the second port P2 and the third port P3 are communicated with each other.

[0103] Figure 10 is a flowchart of a main routine for switching control of the rotary four-way switching valve 12. Unlike the control of the differential pressure driven four-way switching valve 12 in Figure 6, in the control of the rotary four-way switching valve 12 in Figure 10, the equalizing valve 43 is opened when the four-way switching valve 12 is switched in step S431.

[0104] Specifically, prior to switching the four-way switching valve 12, the control unit 9 closes the first shutoff valve 41 and the second shutoff valve 42 and opens the pressure equalizing valve 43 in step S404. Next, in step S431, the control unit 9 switches the four-way switching valve 12 with the pressure equalizing valve 43 open. In step S441, after switching the four-way switching valve 12 is completed, the control unit 9 closes the pressure equalizing valve 43 and opens the first shutoff valve 41 and the second shutoff valve 42.

[0105] It is difficult for the rotary four-way switching valve 12 to switch when there is a large pressure difference between the high-pressure side and the low-pressure side. Therefore, it is sometimes desirable to switch the four-way switching valve 12 with the pressure equalizing valve 43 reliably open.

[0106] Second Embodiment (1) Composition FIG. 11 shows a refrigeration system 100 according to a second embodiment. The refrigeration system 100 differs from the first embodiment in that each of the multiple utilization units 20 can individually select cold energy utilization operation or hot energy utilization operation. To enable such individual selection, the connection pipe 30 has three pipes: a liquid connection pipe 31, a low-pressure gas connection pipe 32, and a high-pressure and low-pressure gas connection pipe 33. The heat source unit 10 also has two four-way switching valves, a first four-way switching valve 12a and a second four-way switching valve 12b, and two gas shut-off valves, a first gas shut-off valve 18a and a second gas shut-off valve 18b. Furthermore, a valve unit 40 is disposed between the heat source unit 10 and each utilization unit 20.

[0107] Each valve unit 40 has two first shutoff valves 41 and a valve control unit 49. One of the two first shutoff valves 41 passes or blocks the refrigerant R between the low-pressure gas communication pipe 32 and the utilization heat exchanger 23, and the other passes or blocks the refrigerant R between the high-pressure and low-pressure gas communication pipe 33 and the utilization heat exchanger 23. The valve control unit 49, together with the heat source control unit 19 and the utilization control unit 29, constitutes the control unit 9 of the refrigeration device 100.

[0108] (2) Features When a switching command Q1 for the first four-way switching valve 12a or the second four-way switching valve 12b is issued from the remote controller 27 of any of the utilization units 20, the control unit 9 closes both of the two first shutoff valves 41 included in each valve unit 40, as in the first embodiment, before the switching operation is performed. This reduces damage to the first four-way switching valve 12a or the second four-way switching valve 12b due to a pressure difference in the refrigerant R.

[0109] (3) Variations In the above-described embodiment, the second shutoff valve 42 is provided in the heat source unit 10. Alternatively, the piping of the refrigerant circuit 90 may be designed so that the second shutoff valve 42 is provided in the valve unit 40.

[0110] <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]

[0111] 9: Control section 10: Heat source unit 11: Compressor 11a: Inlet 11b:Discharge port 12: Four-way switching valve 13:Heat source heat exchanger 19: Heat source control unit 20: Usage unit 23: Utilization heat exchanger 27: Remote controller 29: Usage control section 30: Connecting piping 35: Communication line 40: Valve unit 41: First shutoff valve 42: Second shutoff valve 43 :Pressure equalization valve 49: Valve control section 90: Refrigerant circuit 95: Bypass flow path 100: Refrigeration equipment Q1: Switching command Q2: Switching control signal R: Refrigerant [Prior art documents] [Patent documents]

[0112] [Patent Document 1] Japanese Patent Application Publication No. 63-015056

Claims

1. a compressor (11) having a suction port (11a) for drawing in a refrigerant (R) and a discharge port (11b) for discharging the refrigerant; a refrigerant circuit (90) having a four-way switching valve (12), a heat source heat exchanger (13), and a utilization heat exchanger (23); a control unit (9) that switches the four-way switching valve to switch the circulation path of the refrigerant in the refrigerant circuit; a first shutoff valve (41) disposed between the four-way switching valve and the utilization heat exchanger; Equipped with The control unit closes the first shutoff valve before switching the four-way switching valve. A refrigeration device (100) comprising:

2. a second shutoff valve (42) disposed between the four-way switching valve and the heat source heat exchanger; Furthermore, The control unit further closes the second shutoff valve before switching the four-way switching valve. The refrigeration system of claim 1.

3. a bypass flow path (95) connecting the suction port and the discharge port; a pressure equalization valve (43) configured to open or close the bypass flow path; Furthermore, The control unit further opens the pressure equalizing valve before performing the switching.

3. The refrigeration system of claim 2.

4. The control unit performs the switching of the four-way switching valve after a predetermined time has elapsed after receiving a switching command (Q1) for the four-way switching valve. The refrigeration device according to any one of claims 1 to 3.

5. The control unit stops the compressor after receiving a switching command (Q1) of the four-way switching valve. The refrigeration device according to any one of claims 1 to 3.

6. The control unit before switching the four-way switching valve, closing the first shutoff valve or the second shutoff valve and opening the pressure equalizing valve; The four-way switching valve is switched while the pressure equalizing valve is open, After the switching of the four-way switching valve is completed, the equalizing valve is closed and the first shutoff valve or the second shutoff valve is opened.

4. The refrigeration system of claim 3.

7. The control unit before switching the four-way switching valve, closing the first shutoff valve or the second shutoff valve and opening the pressure equalizing valve; When the pressure difference between the suction port and the discharge port becomes equal to or less than a predetermined value, the pressure equalizing valve is closed; The switching of the four-way switching valve is performed with the pressure equalizing valve closed, After the switching of the four-way switching valve is completed, the first shut-off valve or the second shut-off valve is opened.

4. The refrigeration system of claim 3.

8. The refrigerant is carbon dioxide. The refrigeration device according to any one of claims 1 to 3.

9. a heat source unit (10) having the compressor, the four-way switching valve, and the heat source heat exchanger; a utilization unit (20) having the utilization heat exchanger; a valve unit (40) disposed between the heat source unit and the utilization unit; Furthermore, the first shutoff valve or the second shutoff valve is disposed in the valve unit; The refrigeration device according to claim 2 or 3.

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