Refrigeration device having a four-way switching valve

Abstract

Prevent the refrigerating machine oil mixed in the refrigerant from inhibiting the operation of the four-way switching valve. 【Solution means】The refrigeration device 100 includes a refrigerant circuit 90 and a control unit 9. The refrigerant circuit 90 has a compressor 11, a four-way switching valve 12, and a connection flow path 91 connecting the compressor 11 and the four-way switching valve 12. The refrigerant circuit 90 circulates the refrigerant R. The control unit 9 switches the four-way switching valve 12 to change the circulation path of the refrigerant R in the refrigerant circuit 90. The control unit 9 switches the four-way switching valve 12 when the switching permission condition for the refrigerant R in the connection flow path 91 is satisfied, and does not switch the four-way switching valve 12 when the switching permission condition is not satisfied.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration device having a four-way switching valve.

Background Art

[0002] The four-way switching valve disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 63-015056) is mounted on a refrigeration device for the purpose of switching the circulation direction of the refrigerant. This four-way switching valve is a so-called differential pressure drive type, and the movement of the valve body is caused by using the pressure of the refrigerant passing through the valve chamber.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The refrigerant passing through the four-way switching valve can carry refrigerant oil into the valve chamber or the small-diameter pipe constituting the four-way switching valve. If the refrigerant oil stays in the small-diameter pipe or the like, the movement of the valve body may be hindered by the refrigerant oil, which may interfere with the operation of switching the circulation direction of the refrigerant.

Means for Solving the Problems

[0004] The refrigeration device according to the first aspect includes a refrigerant circuit and a control unit. The refrigerant circuit has a compressor, a four-way switching valve, and a connection flow path connecting the compressor and the four-way switching valve. The refrigerant circuit circulates the refrigerant. The control unit switches the four-way switching valve in order to change the circulation path of the refrigerant in the refrigerant circuit. The control unit switches the four-way switching valve when a switching permission condition regarding the refrigerant in the connection flow path is satisfied, and does not switch the four-way switching valve when the switching permission condition is not satisfied.

[0005] According to this configuration, when the state of the refrigerant in the connection flow path does not satisfy the switching permission condition, the four-way switching valve is not switched. Therefore, it is possible to suppress the switching operation from failing or the switching operation from damaging the four-way switching valve.

[0006] The refrigeration device according to the second aspect is the refrigeration device according to the first aspect, wherein when the control unit receives a switching command to switch the four-way switching valve, the four-way switching valve is not switched when the switching permission condition is not satisfied.

[0007] According to this configuration, even if the control unit receives a switching command, the four-way switching valve is not switched when the switching permission condition is not satisfied. Therefore, it is possible to prevent the switching operation from failing or the switching operation from damaging the four-way switching valve.

[0008] The refrigeration device according to the third aspect is the refrigeration device according to the first aspect or the second aspect, wherein the switching permission condition relates to the fluid number which is an index indicating the refrigerant circulation amount. The fluid number is represented by Fr in the following formula.

[0009]

Equation

[0010] Here, ρ G (kg / m 3 ) is the density of the gas refrigerant. ρ L (kg / m 3 ) is the density of the liquid refrigerant. U G (m / s) is the flow velocity of the gas refrigerant. g (m / s 2 ) is the gravitational acceleration. D (m) is the inner diameter of the pipe constituting the connection flow path.

[0011] According to this configuration, the switching permission condition is related to the refrigerant circulation amount. Therefore, it is possible to determine whether to permit or not permit the switching of the four-way switching valve according to the speed at which the refrigerant circulates.

[0012] The refrigeration device according to the fourth aspect is the refrigeration device according to the third aspect, wherein the switching permission condition is that the fluid number is 1 or more.

[0013] According to this configuration, the switching permission condition is that the circulation amount of the refrigerant is equal to or greater than a predetermined value. Therefore, when the circulation amount of the refrigerant is small and it is predicted that the refrigeration oil remains in the connection flow path, the switching operation may fail due to the presence of the refrigeration oil that can cause resistance to the switching operation, or damage to the four-way switching valve can be suppressed.

[0014] The refrigeration device according to the fifth aspect is the refrigeration device according to any one of the first to third aspects, and when the switching permission condition is not satisfied, the control unit performs an oil purge operation of moving the refrigeration oil existing in the connection flow path downstream of the four-way switching valve by driving the compressor.

[0015] According to this configuration, when it is predicted that the refrigeration oil remains in the connection flow path, the oil purge operation is performed. Therefore, it is possible to suppress the remaining of the refrigeration oil that causes resistance to the switching operation inside the four-way switching valve.

[0016] The refrigeration device according to the sixth aspect is the refrigeration device according to the fifth aspect, and in addition to the case where the switching permission condition is not satisfied, the control unit further performs an oil purge operation at least one of immediately after the start-up and before the stop of the refrigeration device.

[0017] According to this configuration, the oil purge operation is executed immediately after the start-up or before the stop of the refrigeration device. Therefore, it is possible to suppress the remaining of the refrigeration oil inside the four-way switching valve.

[0018] The refrigeration device according to the seventh aspect is the refrigeration device according to any one of the first to sixth aspects, and the connection flow path has a U-shaped pipe protruding downward.

[0019] According to this configuration, the connection flow path has a structure in which the refrigeration oil easily remains. Therefore, by performing the oil purge operation, the refrigeration oil can be effectively removed from the connection flow path and the four-way switching valve.

[0020] The refrigeration device according to the eighth aspect is the refrigeration device according to any one of the first to seventh aspects, and the refrigerant is carbon dioxide.

[0021] According to this configuration, the refrigerant is carbon dioxide. When carbon dioxide is used as the refrigerant, the switching sound of the four-way switching valve tends to be large. In order to reduce the switching sound, a process may be performed to lower the circulation amount of the carbon dioxide refrigerant. As a result, the refrigerant oil tends to stay in the connection flow path. Therefore, by performing the oil purge operation, the refrigerant oil can be effectively removed from the connection flow path and the four-way switching valve.

[0022] The refrigeration device according to the ninth aspect is the refrigeration device according to any one of the first aspect to the eighth aspect, wherein the four-way switching valve includes a valve chamber, a valve body, 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 and a second pilot solenoid valve, a first flow path, a second flow path, and a third flow path. The valve body slides in 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 to the first pilot chamber. The first port receives the refrigerant discharged from the compressor. The second port ejects the refrigerant sucked into the compressor. The third port exchanges the refrigerant with the heat source heat exchanger. The fourth port exchanges the refrigerant with the utilization heat exchanger. The first pilot solenoid valve and the second pilot solenoid valve are arranged at a distance from the valve chamber. The first flow path communicates the first pilot chamber and the first pilot solenoid valve. The second flow path communicates the second pilot chamber and the second pilot solenoid valve. The third flow path communicates the communication path of the first pilot solenoid valve and the second pilot solenoid valve and the second port.

[0023] According to this configuration, the four-way switching valve has a plurality of flow paths that connect the pilot solenoid valve and the valve chamber. Therefore, it is possible to suppress the remaining of the refrigerant oil in the plurality of flow paths by the oil purge operation.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0025] <Embodiment> (1) Overall Configuration The refrigeration device 100 shown in FIG. 1 is for providing hot heat or cold heat obtained from a heat source to a user, and is configured as, for example, an air conditioner. The refrigeration device 100 can perform a cold heat utilization operation for providing cold heat to the user and a warm heat utilization operation for providing warm heat to the user. These respectively correspond to a cooling operation and a heating operation when the refrigeration device 100 is an air conditioner.

[0026] The refrigeration device 100 has a heat source unit 10, a utilization unit 20, a connecting pipe 30, and a communication line 35. A refrigerant circuit 90 for circulating the refrigerant R and a control unit 9 for controlling the refrigerant circuit 90 are constituted by parts of these components.

[0027] As the refrigerant R, any refrigerant can be used, for example, it may be carbon dioxide. In the following description, the refrigerant R is treated as one that can cause a phase change into a liquid, and terms such as "condensation", "evaporation", "liquid refrigerant", and "gas-liquid two-phase refrigerant" are used in the explanation. However, it should be noted that when the refrigerant R is carbon dioxide, there is no phase change into a liquid, so strictly speaking, these terms do not apply.

[0028] (1-1) Heat source unit 10 The heat source unit 10 obtains warm or cold heat from a heat source such as outdoor air. The heat source unit 10 includes, as components of the 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, and a gas shut-off valve 18. The heat source unit 10 also has a heat source fan 14 provided in the vicinity of the heat source heat exchanger 13. The heat source unit 10 further includes a heat source control unit 19 which is a component of the control unit 9. The heat source unit 10 further has a low-pressure sensor S1, a high-pressure sensor S2, a heat source heat exchanger temperature sensor S3, and an outside air temperature sensor S4.

[0029] (1-1-1) Compressor 11 The compressor 11 has a suction pipe 11a and a discharge pipe 11b. The compressor 11 compresses the low-pressure gas refrigerant sucked from the suction pipe 11a to generate a high-pressure gas refrigerant and discharges it from the discharge pipe 11b. A low-pressure sensor S1 is provided near the suction side of the compressor 11, in other words, near the suction pipe 11a. A high-pressure sensor S2 is provided near 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.

[0030] (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 communicating with the discharge pipe 11b. The second port P2 is connected to a pipe communicating with the accumulator 16. The third port P3 is connected to a pipe communicating with the heat source heat exchanger 13. The fourth port P4 is connected to a pipe communicating with the gas shut-off valve 18.

[0031] When the refrigeration device 100 performs a cold heat utilization operation, the four-way switching valve 12 connects the first port P1 and the third port P3 and connects the second port P2 and the fourth port P4 as shown by the solid line in FIG. 1. When the refrigeration device 100 performs a warm heat utilization operation, the four-way switching valve 12 connects the first port P1 and the fourth port P4 and connects the second port P2 and the third port P3 as shown by the broken line in FIG. 1.

[0032] (1-1-3) Heat source heat exchanger 13 The heat source heat exchanger 13 performs heat exchange between the outdoor air and the refrigerant R. The heat source heat exchanger 13 functions as a condenser or radiator for the refrigerant R in the case of cold heat utilization operation, and functions as an evaporator or heat absorber for the refrigerant R in the case of warm heat utilization operation. The heat source heat exchanger temperature sensor S3 provided near the heat source heat exchanger 13 measures the condensation temperature, evaporation temperature, and others of the refrigerant R in the heat source heat exchanger 13.

[0033] (1-1-4) Heat source fan 14 The heat source fan 14 promotes the heat exchange of the heat source heat exchanger 13 by moving the outdoor air and passing it through the heat source heat exchanger 13. The temperature of the outdoor air is measured by the outside air temperature sensor S4.

[0034] (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.

[0035] (1-1-6) Accumulator 16 The accumulator 16 stores the liquid refrigerant component mixed in the gas refrigerant and allows the gas refrigerant to pass through. 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.

[0036] (1-1-7) Liquid shut-off valve 17 The liquid shut-off valve 17 allows or blocks the passage of liquid refrigerant, gas-liquid two-phase refrigerant, etc. The opening and closing of the liquid shut-off valve 17 is manually performed, for example, by the installer of the refrigeration device 100.

[0037] (1-1-8) Gas shut-off valve 18 The gas shut-off valve 18 allows or blocks the passage of low-pressure gas refrigerant, high-pressure gas refrigerant, etc. The opening and closing of the gas shut-off valve 18 is manually performed, for example, by the 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, high-pressure sensor S2, heat source heat exchanger temperature sensor S3, and outside air temperature sensor S4. The heat source control unit 19 also controls the compressor 11, four-way switching valve 12, heat source fan 14, and heat source expansion valve 15.

[0038] (1-2) Utilization unit 20 The utilization unit 20 provides warm or cold heat to the user. The utilization unit 20 has a utilization heat exchanger 23 as a component of the 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.

[0039] (1-2-1) Utilization heat exchanger 23 The utilization heat exchanger 23 performs heat exchange between the indoor air and the refrigerant R. In the case of the cold heat utilization operation, the utilization heat exchanger 23 functions as an evaporator or a heat absorber of the refrigerant R, and in the case of the warm heat utilization operation, it functions as a condenser or a 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 others of the refrigerant R in the utilization heat exchanger 23.

[0040] (1-2-2) Utilization fan 24 The utilization fan 24 promotes the heat exchange of the utilization heat exchanger 23 by moving the indoor air and passing it through 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.

[0041] (1-2-3) Utilization control unit 29 The utilization control unit 29 acquires measurement data from the utilization heat exchanger temperature sensor S5 and the room temperature sensor S6. The utilization control unit 29 also controls the utilization fan 24. In addition, the utilization control unit 29 communicates with the heat source control unit 19 to constitute the control unit 9 together with the heat source control unit 19. The utilization control unit 29 further communicates with the remote controller 27.

[0042] (1-2-4) Remote controller 27 The remote controller 27 receives commands from the user and presents information to the user. The commands from the user include setting the target temperature, setting the air volume, and executing and switching between the cold heat utilization operation and the warm heat utilization operation.

[0043] (1-3) Connection pipe 30 The connection pipe 30 connects the heat source unit 10 and the utilization unit 20 to constitute the refrigerant circuit 90. The connection pipe 30 has a liquid connection pipe 31 and a gas connection pipe 32.

[0044] (1-3-1) Liquid connection pipe 31 The liquid connection pipe 31 connects the liquid shut-off valve 17 and the utilization heat exchanger 23, and moves a liquid refrigerant, a gas-liquid two-phase refrigerant, or the like.

[0045] (1-3-2) Gas connection pipe 32 The gas connection pipe 32 connects the gas shut-off valve 18 and the utilization heat exchanger 23, and moves a low-pressure gas refrigerant, a high-pressure gas refrigerant, or the like.

[0046] (1-4) Communication line 35 The communication line 35 connects the heat source control unit 19 and the utilization control unit 29 in order to constitute the control unit 9. The communication line 35 transmits a control signal, a status, data, and other signals between the heat source control unit 19 and the utilization control unit 29.

[0047] (2) Configuration of the four-way switching valve 12 FIG. 2 shows the detailed configuration of the four-way switching valve 12. The four-way switching valve 12 includes a main valve portion 50, a pilot valve portion 60, and a small-diameter pipe group portion 80.

[0048] (2-1) Main valve portion 50 The main valve portion 50 determines the circulation direction of the refrigerant R. The main valve portion 50 includes a casing 51, a valve body 52, a first piston 53, and a second piston 54.

[0049] (2-1-1) Casing 51 The casing 51 is a cylindrical metal pipe. The internal space of the casing 51 constitutes a valve chamber 51a. Four pipes constituting a first port P1, a second port P2, a third port P3, and a fourth port P4 are connected to the casing 51. Among these, the fourth port P4, the second port P2, and the third port P3 are arranged in a row in this order in the longitudinal direction of the casing 51. Further, the first port P1 is located at a position not aligned with the row of the other ports. The valve chamber 51a is filled with a high-pressure gas refrigerant introduced from the first port P1.

[0050] (2-1-2) Valve body 52 The valve body 52 is a member that slides inside the valve chamber 51a. The valve body 52 has a valve main body 52a having an arch shape, a first connecting portion 52b extending from the valve main body 52a in one direction, and a second connecting portion 52c extending from the valve main body 52a in a direction opposite to the first connecting portion 52b. The valve body 52 is movable in the left - right direction in FIG. 2.

[0051] (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 itself and the casing 51 at 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 through the first piston hole 53a.

[0052] (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. Through the second piston hole 54a, the second pilot chamber 56 First port P1 communicates.

[0053] (2 - 2) Pilot valve section 60 The pilot valve section 60 adjusts the pressure inside the first pilot chamber 55 and the second pilot chamber 56 by controlling the refrigerant R moving to the first pilot chamber 55 and the second pilot chamber 56. The pilot valve section 60 has a first pilot solenoid valve 61, a second pilot solenoid valve 62, and a connection section 63.

[0054] (2 - 2 - 1) First pilot solenoid valve 61 The first pilot solenoid valve 61 controls whether the refrigerant R in 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.

[0055] The first pilot valve body 71 is disposed within the first cylinder 72 and is movable in the left - right direction of FIG. 2. A first pilot valve 71a is formed at the right end of the first pilot valve body 71. The restoring force of the first spring 74 acts to move the first pilot valve body 71 to the right. When an electric current flows through the first coil 73, the first pilot valve body 71 is attracted to the first coil 73 against the restoring force of the first spring 74, thereby moving to the left.

[0056] (2 - 2 - 2) Second pilot solenoid valve 62 The second pilot solenoid valve 62 controls whether the refrigerant R in the second port P2 reaches the second pilot chamber 56. The second pilot solenoid valve 62 includes a second pilot valve body 75, a second cylinder 76, a second coil 77, and a second spring 78.

[0057] The second pilot valve body 75 is disposed within the second cylinder 76 and is movable in the left - right direction of FIG. 2. A second pilot valve 75a is formed at the left end of the second pilot valve body 75. The restoring force of the second spring 78 acts to move the second pilot valve body 75 to the left. When an electric current flows through the second coil 77, the second pilot valve body 75 is attracted to the second coil 77 against the restoring force of the second spring 78, thereby moving to the right.

[0058] (2 - 2 - 3) Connection part 63 The connection part 63 is a member that connects the first pilot solenoid valve 61 and the second pilot solenoid valve 62. The connection part 63 includes 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.

[0059] The first pilot valve seat 65 receives the first pilot valve 71a. The first pilot valve seat 65 communicates with the first connection port 67. When the first pilot solenoid valve 61 closes, it means that the first pilot valve 71a contacts the first pilot valve seat 65. At this time, the first connection port 67 is blocked by the first pilot valve 71a. When the first pilot solenoid valve 61 opens, it means that the first pilot valve 71a separates from the first pilot valve seat 65. At this time, the first connection port 67 is opened.

[0060] The second pilot valve seat 66 receives the second pilot valve 75a. The second pilot valve seat 66 communicates with the second connection port 68. When the second pilot solenoid valve 62 closes, it means that the second pilot valve 75a contacts the second pilot valve seat 66. At this time, the second connection port 68 is blocked by the second pilot valve 75a. When the second pilot solenoid valve 62 opens, it means that the second pilot valve 75a separates from the second pilot valve seat 66. At this time, the second connection port 68 is opened.

[0061] The communication passage 64 communicates 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 through 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 through the communication passage 64.

[0062] (2-3) Small-diameter tube group part 80 The small-diameter tube group part 80 is an aggregate 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.

[0063] (3) Operation of the four-way switching valve 12 (3-1) State of the cold and heat utilization operation Figure 2 shows the arrangement of each part of the four-way switching valve 12 for performing the cold and heat utilization operation. The valve body 52 is located on the left side. As a result, the valve body 52 communicates the second port P2 with the fourth port P4 and also communicates the first port P1 with the third port P3 .

[0064] To position the valve body 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 communicates with the first pilot chamber 55 via the third flow path 83, the third connection port 69, the communication path 64, the first connection port 67, and the first flow path 81. Since 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 sucked into the second port P2. Note that since 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.

[0065] Since 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 the high-pressure gas refrigerant flowing in from the second piston hole 54a.

[0066] A force that tries to move the valve body 52 to the left acts 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. Therefore, the valve body 52 can be stably positioned on the left side.

[0067] (3-2) Transient state Figure 3 shows the transient state of the four-way switching valve 12 when switching from the cold and heat utilization operation to the heat utilization operation. For the switching of 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 path 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 sucked into the second port P2.

[0068] Since 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 the high-pressure gas refrigerant flowing in from the first piston hole 53a.

[0069] 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.

[0070] (3-3) State of the heat utilization operation Figure 4 shows the arrangement of each part of the four-way switching valve when performing the heat utilization operation. Similar to the transient state in Figure 3, the first pilot solenoid valve 61 is closed, and the second pilot solenoid valve 62 is open. The valve body 52 located on the right side communicates the second port P2 with the third port P3 and also communicates the first port P1 with the fourth port P4 .

[0071] 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, a force acts to move the valve body 52 to the right. Therefore, the valve body 52 can be stably positioned on the right side.

[0072] To perform the cold heat utilization operation again, control is performed to open the first pilot solenoid valve 61 and close the second pilot solenoid valve 62. Thereby, while filling the first pilot chamber 55 with the low-pressure gas refrigerant and filling the second pilot chamber 56 with the high-pressure gas refrigerant, a force is generated to move the valve body 52 to the left.

[0073] (4) Control of the four-way switching valve 12 (4-1) Electrical system of the refrigeration device 100 FIG. 5 shows the electrical system of the refrigeration device 100. The control unit 9 receives the measured data of the low-pressure sensor S1, the high-pressure sensor S2, the heat source heat exchanger temperature sensor S3, the outside air temperature sensor S4, the utilization heat exchanger temperature sensor S5, and the room temperature sensor S6, and the commands of the user transmitted from the remote controller 27. Further, the control unit 9 outputs control signals for the compressor 11, the four-way switching valve 12, the heat source fan 14, the heat source expansion valve 15, and the utilization fan 24.

[0074] Among the commands transmitted from the remote controller 27, there is a switching command Q1 for the four-way switching valve 12. For example, when the user inputs to the remote controller 27 to execute the warm heat utilization operation while the refrigeration device 100 is executing the cold heat utilization operation, the remote controller 27 transmits a switching command Q1 to the control unit 9 to switch the four-way switching valve 12 for performing the warm heat utilization operation. Alternatively, when the user inputs to the remote controller 27 to execute the cold heat utilization operation while the refrigeration device 100 is executing the warm heat utilization operation, the remote controller 27 transmits a switching command Q1 to the control unit 9 to switch the four-way switching valve 12 for performing the cold heat utilization operation.

[0075] When the control unit 9 receives the switching command Q1, it outputs a switching control signal Q2 for the four-way switching valve 12 by performing a predetermined calculation. 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.

[0076] (4-2) Connection flow path 91 FIG. 6 shows the connecting pipe between the compressor 11 and the four-way switching valve 12. The discharge pipe 11b of the compressor 11 and the first port P1 of the four-way switching valve 12 are connected by a connection flow path 91. The connection flow path 91 includes a filter 92 and a U-shaped pipe 93 protruding downward. Refrigeration machine oil carried by the refrigerant R is likely to be stored in the U-shaped pipe 93 due to the action of gravity.

[0077] Part of the refrigerant oil stored in the U-shaped tube 93 may enter the four-way switching valve 12 from the first port P1 due to the high-pressure refrigerant discharged from the discharge pipe 11b. The refrigerant oil in the four-way switching valve 12 may clog the first flow path 81, the second flow path 82, the third flow path 83, the first piston hole 53a, the second piston hole 54a, etc., thereby hindering the movement of the valve body 52, the first piston 53, and the second piston 54. Thus, the refrigerant oil may prevent the four-way switching valve 12 from switching the circulation direction of the refrigerant R.

[0078] (4-3) Switching control FIG. 7 is a flowchart of the main routine of the switching control of the four-way switching valve 12. In step S100, the switching control starts. In step S101, the control unit 9 checks whether it has already received the switching command Q1 issued from the remote controller 27 according to the user's input. If not yet received (S101: NO), the process returns to step S101. If already received (S101: YES), the process proceeds to step S102.

[0079] In step S102, the control unit 9 checks whether the switching permission condition is satisfied. The switching permission condition relates to the fluid number indicating the refrigerant circulation amount. The fluid number is represented by Fr in the following formula.

[0080] [Number]

[0081] Here, ρ G (kg / m 3 ) is the density of the gas refrigerant, ρ L (kg / m 3 ) is the density of the liquid refrigerant, U G (m / s) is the flow velocity of the gas refrigerant in the connection flow path 91, g (m / s 2 ) is the gravitational acceleration, and D (m) is the inner diameter of the pipe constituting the connection flow path 91.

[0082] Among these, ρ G(kg / m 3 ), ρ L (kg / m 3 ), and g (m / s 2 ) are constants and can be input in advance to the control unit 9. Also, since D (m) is a design value, it can be input in advance to the control unit 9 in the same manner. U G (m / s) can be calculated based on the parameter of the rotational speed of the compressor 11 output by the control unit 9.

[0083] For example, the switching Permission conditions can be set as follows.

[0084]

Equation

[0085] This means that the refrigerant circulation amount in the connection flow path 91 is equal to or greater than a predetermined value.

[0086] When the switching permission condition is satisfied (S102: YES), the process proceeds to step S104. On the other hand, when the switching permission condition is not satisfied (S102: NO), the process proceeds to step S103.

[0087] In step S103, a subroutine of the oil purge operation is executed. The oil purge operation is an operation that uses the high-pressure gas refrigerant discharged from the compressor 11 to blow away the refrigeration machine oil existing in the connection flow path 91 and move the refrigeration machine oil to the downstream of the four-way switching valve 12. The subroutine of the oil purge operation will be described later. When the oil purge operation ends, the process proceeds to step S104.

[0088] 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.

[0089] Thereafter, in step S105, the switching control of the four-way switching valve 12 ends.

[0090] Figure 8 is a flowchart of a subroutine for an oil purge operation. In step S200, the oil purge 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.

[0091] In step S203, the count value of the timer of the control unit 9 is reset to zero. In step S204, the control unit 9 starts the timer. In step S205, the control unit 9 refers to the 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 (S205: NO), the process returns to step S205. On the other hand, if the predetermined time has elapsed (S205: YES), the process proceeds to step S206. In step S206, the control unit 9 ends the timer. In step S207, the subroutine for the oil purge operation ends.

[0092] Figure 9 is a flowchart of a subroutine for the output process of the switching control signal Q2. In step S300, the output of the switching control signal Q2 is started. In step S301, the control unit 9 checks the content of the switching command Q1 that has already been received. If the content of the switching command Q1 requests the execution of a cooling / heating operation (step S301: cooling / heating operation), the process proceeds to step S302. In step S302, the control unit 9 opens the first pilot solenoid valve 61 and outputs a switching control signal Q2 to close the second pilot solenoid valve 62. Then, in step S304, the output process of the switching control signal Q2 ends.

[0093] On the other hand, when the content of the switching command Q1 requests the execution of the heat utilization operation (step S301: heat utilization operation), the process proceeds to step S303. In step S303, the control unit 9 closes the first pilot solenoid valve 61 and outputs a switching control signal Q2 for opening the second pilot solenoid valve 62. Then, in step S304, the output process of the switching control signal Q2 ends.

[0094] (5) Features (5-1) When the state of the refrigerant R in the connection flow path 91 does not satisfy the switching permission condition, the four-way switching valve 12 is not switched. Even if the control unit 9 receives the switching command Q1, the four-way switching valve 12 is not switched when the switching permission condition is not satisfied. Therefore, it is possible to suppress the switching operation from failing or damaging the four-way switching valve 12.

[0095] (5-2) The switching permission condition is related to the refrigerant circulation amount. Therefore, it is possible to determine whether to permit or not permit the switching of the four-way switching valve 12 according to the speed of the refrigerant R that can blow off the refrigerating machine oil.

[0096] (5-3) The switching permission condition is that the fluid value related to the circulation amount of the refrigerant R is a predetermined value, that is, 1 or more. Therefore, when the circulation amount of the refrigerant R is small and it is expected that the refrigerating machine oil stays in the connection flow path 91, it is possible to suppress the switching operation from failing or the four-way switching valve 12 from being damaged due to the presence of the refrigerating machine oil that can be a resistance to the switching operation.

[0097] (5-4) When it is expected that the refrigerating machine oil stays in the connection flow path 91, the compressor 11 is driven before the switching of the four-way switching valve 12, and thus the oil purge operation is performed. Therefore, it is possible to suppress the refrigerating machine oil that is a resistance to the switching operation from remaining inside the four-way switching valve 12.

[0098] (5-5) Since it has the U-shaped pipe 93 protruding downward, the connection flow path 91 has a structure that easily retains the refrigerating machine oil. Therefore, by performing the oil purge operation, the refrigerating machine oil can be effectively removed from the connection flow path 91 and the four-way switching valve 12.

[0099] (5-6) The refrigerant R may be carbon dioxide. When carbon dioxide is used as the refrigerant R, the switching sound of the four-way switching valve 12 tends to be large. In order to reduce the switching sound, a process of lowering the circulation amount of the carbon dioxide refrigerant may be performed. As a result, the refrigerating machine oil easily stays in the connection flow path 91. Therefore, by performing the oil purge operation, the refrigerating machine oil can be effectively removed from the connection flow path 91 and the four-way switching valve 12.

[0100] (5-7) The four-way switching valve 12 has a first flow path 81, a second flow path 82, and a third flow path 83 that connect the first pilot solenoid valve 61 or the second pilot solenoid valve 62 and the valve chamber 51a. Therefore, by the oil purge operation, it is possible to suppress the remaining of the refrigerating machine oil in narrow flow paths such as the first flow path 81, the second flow path 82, and the third flow path 83.

[0101] (6) Modification (6-1) First modification In the above-described embodiment, the oil purge operation is executed when the switching command Q1 is issued. Instead of this, or in addition to this, the oil purge operation may be executed immediately after the start-up or before the stop of the refrigeration device 100. In this case, the remaining of the refrigerating machine oil inside the four-way switching valve 12 is further suppressed.

[0102] (6-2) Second modification In the above-described embodiment, the first pilot solenoid valve 61 and the second pilot solenoid valve 62 are opened when current is passed through the first coil 73 or the second coil 77, respectively. Instead of this, the first pilot solenoid valve 61 and the second pilot solenoid valve 62 may be closed when current is passed through the first coil 73 or the second coil 77, respectively.

[0103] (6-3) Third modification In the foregoing embodiment, the switching command Q1 is issued by the remote controller 27. Alternatively, the switching command Q1 may be issued by other parts. 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 measured value of the heat source heat exchanger temperature sensor S3 that the heat source heat exchanger 13 is dewing while the refrigeration device 100 is performing the warm heat utilization operation, the control unit 9 can issue a switching control signal Q2 for executing the cold heat utilization operation to the four-way switching valve 12, thereby performing the defrost operation.

[0104] (6-4) Fourth Modified Example In the foregoing embodiment, in the oil purge operation shown in FIG. 8, the operation content of the compressor 11 does not particularly change from the normal operation. In other words, the content of the oil purge operation is that the control of the first pilot solenoid valve 61 and the second pilot solenoid valve 62 is not performed for a predetermined time. Alternatively, in the oil purge operation, the operation content of the compressor 11 may be changed from the normal operation. For example, in the oil purge operation, the rotation speed of the compressor 11 may be decreased to a predetermined small value, or may be increased to a predetermined large value.

[0105] <Conclusion> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure described in the claims.

Explanation of Reference Numerals

[0106] 9: Control unit 10: Heat source unit 11: Compressor 11a: Suction pipe 11b: Discharge pipe 12: Four-way switching valve 13: Heat source heat exchanger 15: Heat source expansion valve 19: Heat source control unit 20: Utilization unit 23: Utilization heat exchanger 29: Utilization control unit 30: Connecting pipe 50: Main valve section 51: Casing 51a: Valve chamber 52: Valve body 52a: Valve main body 52b: First connection part 52c: Second connection part 53: First piston 53a: First piston hole 54: Second piston 54a: Second piston hole 55: First pilot chamber 56: Second pilot chamber 60: Pilot valve section 61: First pilot solenoid valve 62: Second pilot solenoid valve 63: Connection part 64: Communication passage 65: First pilot valve seat 66: Second pilot valve seat 67: First connection port 68: Second connection port 69: Third connection port 71: First pilot valve body 71a: First pilot valve 75: Second pilot valve body 75a: Second pilot valve 80: Small-diameter pipe group section 81: First flow path 82: Second flow path 83: Third flow path 90: Refrigerant circuit 91: Connection flow path 93: U-shaped pipe 100: Refrigeration device P1: First port P2: Second port P3: Third port P4: Fourth port Q1: Switching command Q2: Switching control signal R: Refrigerant

Prior art documents

Patent Document

[0107]

Patent Document 1

Claims

1. A refrigerant circuit (90) having a compressor (11), a four-way switching valve (12), and a connecting flow path (91) connecting the compressor and the four-way switching valve, for circulating a refrigerant (R); Refrigerating machine oil that can be carried through the refrigerant circuit by the refrigerant; A control unit (9) for switching the four-way switching valve to change the circulation path of the refrigerant in the refrigerant circuit; Comprising: When a switching permission condition meaning that the refrigerating machine oil does not stay in the connecting flow path is satisfied, the control unit performs the switching of the four-way switching valve, and when the switching permission condition is not satisfied, the control unit does not perform the switching of the four-way switching valve; The switching permission condition relates to a fluid number which is an index indicating the refrigerant circulation amount; The fluid number is represented by Fr in the following formula: 【Number 1】 Here, ρG (kg / m3) is the density of the gaseous refrigerant, ρL (kg / m3) is the density of the liquid refrigerant, UG (m / s) is the flow velocity of the gaseous refrigerant, g (m / s2) is the acceleration due to gravity, and D (m) is the inner diameter of the pipe constituting the connecting flow path; A refrigeration device (100).

2. When receiving a switching command (Q1) indicating that the four-way switching valve should be switched, if the switching permission condition is not satisfied, the control unit does not perform the switching of the four-way switching valve; The refrigeration device according to Claim 1.

3. The switching permission condition is that the fluid number is 1 or more; The refrigeration device according to Claim 1.

4. When the switching permission condition is not satisfied, the control unit performs an oil purge operation of moving the refrigerating machine oil existing in the connecting flow path downstream of the four-way switching valve by driving the compressor; The refrigeration device according to any one of Claims 1 to 3.

5. In addition to when the switching permission condition is not satisfied, the control unit further performs the oil purge operation at least one of immediately after starting and before stopping the refrigeration device; The refrigeration device according to Claim 4.

6. The connecting flow path has a U-shaped pipe (93) protruding downward; The refrigeration device according to any one of Claims 1 to 3.

7. The refrigerant is carbon dioxide; The refrigeration device according to any one of Claims 1 to 3.

8. The four-way switching valve includes: A valve chamber (51); A valve body (52) sliding 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 chamber for receiving the refrigerant discharged from the compressor, a second port (P2) for ejecting the refrigerant sucked into the compressor, a third port (P3) for exchanging the refrigerant with a heat source heat exchanger, and a fourth port (P4) for exchanging the refrigerant with a utilization heat exchanger; A first pilot solenoid valve (61) and a second pilot solenoid valve (62) disposed apart from the valve chamber; A first flow path (81) for communicating the first pilot chamber with the first pilot solenoid valve; A second flow path (82) for communicating the second pilot chamber with the second pilot solenoid valve; A third flow path (83) for communicating a communication path (64) of the first pilot solenoid valve and the second pilot solenoid valve with the second port; and The refrigeration device according to any one of claims 1 to 3.

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