Refrigerating device having four-way switching valve

Abstract

To restrain refrigeration oil mixed with a refrigerant from blocking an operation of a four-way switching valve.SOLUTION: A refrigerating device 100 comprises a refrigerant circuit 90, and a control part 9. The refrigerant circuit 90 has a compressor 11, a four-way switching valve 12, and a connection flow path 91 coupling the compressor 11 and the four-way switching valve 12. The refrigerant circuit 90 circulates a refrigerant R. The control part 9 switches the four-way switching valve 12 to change a circulation path of the refrigerant R in the refrigerant circuit 90. The control part 9 switches the four-way switching valve 12 when a switching permission condition relating to 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.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] The refrigerant passing through the four-way valve may bring refrigeration oil into the valve chamber or small diameter pipes that make up the four-way valve. If refrigeration oil accumulates in the small diameter pipes, the refrigeration oil may impede the movement of the valve disc, causing problems with switching the refrigerant circulation direction. [Means for solving the problem]

[0004] A refrigeration device according to a first aspect includes a refrigerant circuit and a control unit. The refrigerant circuit has a compressor, a four-way switching valve, and a connecting flow path connecting the compressor and the four-way switching valve. The refrigerant circuit circulates a refrigerant. The control unit switches the four-way switching valve 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 related to the refrigerant in the connecting 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, the four-way switching valve is not switched if the state of the refrigerant in the connecting flow path does not satisfy the switching permission condition, thereby preventing the switching operation from failing or damaging the four-way switching valve.

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

[0007] With this configuration, even if the control unit receives a switching command, it will not switch the four-way switching valve unless the switching permission conditions are satisfied, thereby preventing the switching operation from failing or damaging the four-way switching valve.

[0008] A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the first or second aspect, wherein the switching permission condition relates to the Froude number, which is an index indicating the amount of refrigerant circulating. The Froude number is expressed by Fr in the following equation:

[0009]

number

[0010] where ρ G (kg / m 3 ) is the density of the gas refrigerant. 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 that makes up the connecting flow path.

[0011] According to this configuration, the condition for permitting switching is related to the amount of refrigerant circulating, and therefore, whether or not the switching of the four-way switching valve is permitted can be determined depending on the speed at which the refrigerant circulates.

[0012] A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the third aspect, wherein the switching permission condition is that the Froude number is 1 or greater.

[0013] According to this configuration, the condition for permitting switching is that the refrigerant circulation volume is equal to or greater than a predetermined value. Therefore, when the refrigerant circulation volume is small and refrigerant oil is expected to accumulate in the connecting flow path, it is possible to prevent the switching operation from failing or the four-way switching valve from being damaged due to the presence of refrigerant oil that could act as a resistance to the switching operation.

[0014] A refrigeration apparatus according to a fifth aspect is a refrigeration apparatus according to any one of the first aspect to the third aspect, wherein when the switching permission condition is not satisfied, the control unit drives the compressor to perform oil purging operation to move refrigeration oil present in the connecting flow path downstream of the four-way switching valve.

[0015] According to this configuration, when refrigeration oil is expected to remain in the connecting flow path, the oil purge operation is performed, thereby preventing refrigeration oil from remaining inside the four-way switching valve, which would otherwise cause resistance to the switching operation.

[0016] A refrigeration apparatus according to a sixth aspect is a refrigeration apparatus according to the fifth aspect, wherein the control unit performs oil purging operation not only when the switching permission condition is not satisfied, but also at least one of immediately after starting the refrigeration apparatus and before stopping it.

[0017] According to this configuration, the oil purge operation is performed immediately after starting up or before stopping the refrigeration system, thereby preventing refrigeration oil from remaining inside the four-way selector valve.

[0018] A refrigeration apparatus according to a seventh aspect is the refrigeration apparatus according to any one of the first aspect to the sixth aspect, wherein the connecting flow path has a U-shaped tube that protrudes downward.

[0019] According to this configuration, the connecting flow path has a structure that makes it easy for refrigerating machine oil to accumulate, and therefore, by performing the oil purge operation, refrigerating machine oil can be effectively removed from the connecting flow path and the four-way selector valve.

[0020] 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.

[0021] In this configuration, the refrigerant is carbon dioxide. When carbon dioxide is used as the refrigerant, the switching noise of the four-way switching valve tends to be loud. To reduce the switching noise, the amount of carbon dioxide refrigerant circulated is sometimes reduced, which results in refrigeration oil easily accumulating in the connecting flow path. Therefore, by performing the oil purge operation, the refrigeration oil can be effectively removed from the connecting flow path and the four-way switching valve.

[0022] A refrigeration apparatus according to a ninth aspect is the refrigeration apparatus according to any one of the first to eighth aspects, wherein the four-way selector valve has a valve chest, a valve element, a first pilot chamber, a second pilot chamber, a first port, a second port, a third port, and a fourth port formed in the valve chest, a first pilot solenoid valve and a second pilot solenoid valve, and a first flow path, a second flow path, and a third flow path. The valve element slides within the valve chest. The first pilot chamber is formed at an end of the valve chest. The second pilot chamber is formed at an end of the valve chest opposite the first pilot chamber. The first port receives refrigerant discharged from the compressor. The second port ejects refrigerant drawn into the compressor. The third port exchanges refrigerant with a heat source heat exchanger. The fourth port exchanges refrigerant with a utilization heat exchanger. The first pilot solenoid valve and the second pilot solenoid valve are disposed away from the valve chest. The first flow path connects the first pilot chamber to the first pilot solenoid valve, the second flow path connects the second pilot chamber to the second pilot solenoid valve, and the third flow path connects the communication passages of the first and second pilot solenoid valves to the second port.

[0023] According to this configuration, the four-way selector valve has a plurality of flow paths that connect the pilot solenoid valve and the valve chamber, and therefore, the oil purge operation can prevent refrigeration oil from remaining in the plurality of flow paths. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a circuit diagram showing the configuration of a refrigeration device 100. FIG. [Figure 2] FIG. 2 is a cross-sectional schematic view showing the four-way switching valve 12 in cold energy utilization operation. [Figure 3] 4 is another schematic cross-sectional view showing the four-way switching valve 12 in a transient state. FIG. [Figure 4] FIG. 10 is another cross-sectional schematic view showing the four-way switching valve 12 in the heat utilization operation. [Figure 5] FIG. 2 is a block diagram showing an electrical system of the refrigeration device 100. [Figure 6] 2 is a schematic diagram showing the connecting pipe between the compressor 11 and the four-way switching valve 12. FIG. [Figure 7] 4 is a flowchart of the switching control of the four-way switching valve 12. [Figure 8] 10 is a flowchart of an oil purge operation. [Figure 9] 10 is a flowchart of an output process of a switching control signal Q2. DETAILED DESCRIPTION OF THE INVENTION

[0025] <Embodiment> (1) Overall structure The refrigeration device 100 shown in Fig. 1 is configured as, for example, an air conditioner, for providing a user with hot heat or cold heat obtained from a heat source. The refrigeration device 100 can perform a 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 device 100 is an air conditioner, these operations correspond to a cooling operation and a heating operation, respectively.

[0026] The refrigeration device 100 has a heat source unit 10, a utilization unit 20, a connecting pipe 30, and a communication line 35. These components constitute a refrigerant circuit 90 that circulates the refrigerant R, and a control unit 9 that controls the refrigerant circuit 90.

[0027] 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.

[0028] (1-1) Heat source unit 10 The heat source unit 10 obtains heat or cold from a heat source such as outdoor air. The heat source unit 10 has a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source expansion valve 15, an accumulator 16, a liquid shut-off valve 17, and a gas shut-off valve 18 as components of a refrigerant circuit 90. The heat source unit 10 also has a heat source fan 14 provided near the heat source heat exchanger 13. The heat source unit 10 further has a heat source control unit 19, which is a component of the control unit 9. The heat source unit 10 also has a low-pressure sensor S1, a high-pressure sensor S2, a heat source heat exchanger temperature sensor S3, and an outdoor air temperature sensor S4.

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

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

[0031] 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.

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

[0033] (1-1-4) Heat source fan 14 The heat source fan 14 moves the outdoor air through the heat source heat exchanger 13, thereby promoting heat exchange in the heat source heat exchanger 13. The temperature of the outdoor air is measured by the outdoor air temperature sensor S4.

[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 liquid refrigerant components mixed in the gas refrigerant and allows the gas refrigerant to pass through it. The accumulator 16 is connected to the suction pipe 11a of the compressor 11. The accumulator 16 prevents the liquid refrigerant from being sucked into the compressor 11.

[0036] (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.

[0037] (1-1-8) Gas shutoff valve 18 The gas shutoff valve 18 allows or blocks the passage of low-pressure gas refrigerant or high-pressure gas refrigerant. The gas shutoff valve 18 is opened and closed manually by, for example, an installer of the refrigeration device 100. (1-1-9) Heat source control unit 19 The heat source control unit 19 acquires measurement data from the low pressure sensor S1, the high pressure sensor S2, the heat source heat exchanger temperature sensor S3, and the outside air temperature sensor S4. The heat source control unit 19 also controls the compressor 11, the four-way switching valve 12, the heat source fan 14, and the heat source expansion valve 15.

[0038] (1-2) Usage unit 20 The utilization unit 20 provides hot or cold heat to a user. The utilization unit 20 has a utilization heat exchanger 23 as a component of a refrigerant circuit 90. The utilization unit 20 also has a utilization fan 24 provided near the utilization heat exchanger 23. The utilization unit 20 further has a utilization control unit 29 which is a component of the control unit 9. The utilization unit 20 further has a utilization heat exchanger temperature sensor S5 and a room temperature sensor S6. A remote controller 27 is connected to the utilization control unit 29 by wire or wirelessly.

[0039] (1-2-1) Utilized heat exchanger 23 The utilization heat exchanger 23 exchanges heat between the indoor air and the refrigerant R. In cold heat utilization operation, the utilization heat exchanger 23 functions as an evaporator or heat absorber of the refrigerant R, and in hot heat utilization operation, functions as a condenser or heat radiator of the refrigerant R. The utilization heat exchanger temperature sensor S5 provided near the utilization heat exchanger 23 measures the condensation temperature, evaporation temperature, and other temperatures of the refrigerant R in the utilization heat exchanger 23.

[0040] (1-2-2) 24 fans in use The utilization fan 24 moves the indoor air through the utilization heat exchanger 23, thereby promoting heat exchange in the utilization heat exchanger 23. The utilization fan 24 also sends the air conditioned by the utilization heat exchanger 23 to the vicinity of the user. The temperature of the indoor air is measured by the room temperature sensor S6.

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

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

[0043] (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.

[0044] (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.

[0045] (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.

[0046] (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.

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

[0048] (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 .

[0049] (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.

[0050] (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.

[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 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.

[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. The second pilot chamber 56 communicates with the second port P2 via the second piston hole 54a.

[0053] (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.

[0054] (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.

[0055] 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.

[0056] (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.

[0057] 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.

[0058] (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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] (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.

[0063] (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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] (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.

[0068] 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.

[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) 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.

[0071] 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.

[0072] 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.

[0073] (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, high-pressure sensor S2, heat-source heat exchanger temperature sensor S3, outside air temperature sensor S4, utilization heat exchanger temperature sensor S5, and room temperature sensor S6, as well as user commands transmitted from a remote controller 27. The control unit 9 also outputs control signals to the compressor 11, four-way switching valve 12, heat-source fan 14, heat-source expansion valve 15, and utilization fan 24.

[0074] 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.

[0075] 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.

[0076] (4-2) Connection channel 91 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 connecting flow path 91. The connecting flow path 91 includes a filter 92 and a U-shaped pipe 93 that protrudes downward. Refrigerating machine oil carried by the refrigerant R tends to accumulate in the U-shaped pipe 93 due to the action of gravity.

[0077] A situation may occur in which some of the refrigeration oil stored in the U-shaped pipe 93 enters the four-way selector valve 12 from the first port P1 due to the high-pressure refrigerant discharged from the discharge pipe 11b. The refrigeration oil in the four-way selector 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 inhibiting the movement of the valve body 52, the first piston 53, and the second piston 54. In this way, the refrigeration oil may interfere with the operation of the four-way selector valve 12 to switch the circulation direction of the refrigerant R.

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

[0079] In step S102, the control unit 9 checks whether the switching permission conditions are satisfied. The switching permission conditions relate to the Froude number, which indicates the amount of refrigerant circulating. The Froude number is expressed by Fr in the following equation.

[0080]

number

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

[0082] Of these, ρ G(kg / m 3 ), ρ L (kg / m 3 ), and g (m / s 2 ) is a constant, so it can be input to the control unit 9 in advance. Also, D(m) is a design value, so it can be input to the control unit 9 in advance as well. U G (m / s) can be calculated based on the parameter of the rotation speed of the compressor 11 output by the control unit 9.

[0083] For example, the switching condition can be set as follows:

[0084]

number

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

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

[0087] In step S103, an oil purge operation subroutine is executed. The oil purge operation is an operation in which the high-pressure gas refrigerant discharged from the compressor 11 is used to blow away the refrigeration oil present in the connecting flow path 91 and move the refrigeration oil downstream of the four-way switching valve 12. The oil purge operation subroutine 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] 8 is a flowchart of the oil purge operation subroutine. 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 timing the timer. In step S205, the control unit 9 references the count value of the timer and checks whether a predetermined time has elapsed. The predetermined time is, for example, 5 seconds. If the predetermined time has not elapsed (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 timing the timer. In step S207, the oil purge operation subroutine ends.

[0092] 9 is a flowchart of a subroutine for processing to output the switching control signal Q2. In step S300, output of the switching control signal Q2 begins. In step S301, the control unit 9 checks the content of the switching command Q1 that it has already received. If the content of the switching command Q1 requests execution of cold energy utilization operation (step S301: cold energy utilization operation), the process proceeds to step S302. In step S302, the control unit 9 outputs a switching control signal Q2 to open the first pilot solenoid valve 61 and close the second pilot solenoid valve 62. Thereafter, in step S304, the process to output the switching control signal Q2 ends.

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

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

[0095] (5-2) The switching permission condition is related to the amount of refrigerant circulating. Therefore, whether or not the switching of the four-way switching valve 12 is permitted can be determined depending on the speed at which the refrigerant R can blow away the refrigeration oil.

[0096] (5-3) The condition for permitting switching is that the fluid value related to the circulation amount of refrigerant R is a predetermined value, i.e., equal to or greater than 1. Therefore, when the circulation amount of refrigerant R is small and it is expected that refrigerant oil will accumulate in the connection flow path 91, it is possible to prevent the switching operation from failing or the four-way switching valve 12 from being damaged due to the presence of refrigerant oil that could act as a resistance to the switching operation.

[0097] (5-4) When it is expected that refrigerating machine oil is accumulated in the connection flow path 91, the compressor 11 is driven before switching of the four-way switching valve 12, thereby performing oil purge operation. Therefore, refrigerating machine oil that would cause resistance to the switching operation is prevented from remaining inside the four-way switching valve 12.

[0098] (5-5) The connection flow path 91 has a structure that makes it easy for refrigeration oil to accumulate due to the presence of the downwardly protruding U-shaped pipe 93. Therefore, by performing the oil purge operation, refrigeration 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 noise of the four-way switching valve 12 tends to become louder. In order to reduce the switching noise, a process is sometimes performed to reduce the amount of carbon dioxide refrigerant circulated, which results in refrigeration oil tending to accumulate in the connecting flow path 91. Therefore, by performing the oil purge operation, the refrigeration oil can be effectively removed from the connecting 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 to the valve chamber 51a. Therefore, the oil purge operation can prevent refrigeration oil from remaining in narrow flow paths such as the first flow path 81, the second flow path 82, and the third flow path 83.

[0101] (6) Variations (6-1) First Modification In the above-described embodiment, the oil purge operation is executed when the switching command Q1 is issued. Alternatively, or in addition, the oil purge operation may be executed immediately after starting or before stopping the refrigeration system 100. In this case, refrigeration oil is further prevented from remaining inside the four-way switching valve 12.

[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 flows through the first coil 73 or the second coil 77, respectively. Alternatively, the first pilot solenoid valve 61 and the second pilot solenoid valve 62 may be closed when current flows through the first coil 73 or the second coil 77, respectively.

[0103] (6-3) Third Modification In the above-described embodiment, the switching command Q1 is issued by the remote controller 27. Alternatively, the switching command Q1 may be issued by another component. For example, the switching command Q1 can be issued using the output of the heat source heat exchanger temperature sensor S3 as a trigger. When the control unit 9 recognizes from the measurement value of the heat source heat exchanger temperature sensor S3 that condensation has formed on the heat source heat exchanger 13 while the refrigeration apparatus 100 is performing a hot heat utilization operation, the control unit 9 can perform a defrost operation by issuing a switching control signal Q2 to the four-way switching valve 12 to execute a cold heat utilization operation.

[0104] (6-4) Fourth Modification In the above-described embodiment, the operation of the compressor 11 during the oil purge operation shown in Fig. 8 is not particularly different from normal operation. In other words, the oil purge operation is such that the first pilot solenoid valve 61 and the second pilot solenoid valve 62 are not controlled for a predetermined time. Alternatively, the operation of the compressor 11 during the oil purge operation may be different from normal operation. For example, during the oil purge operation, the rotation speed of the compressor 11 may be reduced to a predetermined small value or 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 can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0106] 9: Control section 10: Heat source unit 11: Compressor 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: Usage unit 23: Utilization heat exchanger 29: Usage control section 30: Connecting piping 50: Main valve section 51: Casing 51a: Valve chamber 52: Valve body 52a: Valve body 52b: 1st connection part 52c: 2nd connection part 53: First piston 53a: First piston hole 54: Second piston 54a: Second piston hole 55: First Pilot Room 56: Second pilot room 60: Pilot valve section 61: First pilot solenoid valve 62: Second pilot solenoid valve 63: Connection part 64:Communication path 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 tube group section 81: First flow path 82: Second flow path 83: Third flow path 90: Refrigerant circuit 91: Connecting channel 93 :U-shaped tube 100: Refrigeration equipment P1: First port P2: Second port P3: Third port P4: 4th port Q1: Switching command Q2: Switching control signal R: Refrigerant [Prior art documents]

Charter Documents

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

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, and circulating a refrigerant (R); a control unit (9) that switches the four-way switching valve to change the circulation path of the refrigerant in the refrigerant circuit; Equipped with the control unit performs the switching of the four-way switching valve when a switching permission condition for the refrigerant in the connection flow path is satisfied, and does not perform the switching of the four-way switching valve when the switching permission condition is not satisfied. A refrigeration device (100).

2. When the control unit receives a switching command (Q1) to switch the four-way switching valve, the control unit does not switch the four-way switching valve if the switching permission condition is not satisfied. The refrigeration system of claim 1.

3. The switching permission condition relates to a Froude number, which is an index indicating the amount of refrigerant circulating, The Froude number is represented by Fr in the following formula: [Equation 1] where ρ G (kg / m 3 ) is the density of the gas refrigerant, and ρ L (kg / m 3 ) is the density of the liquid refrigerant, and U G (m / s) is the flow velocity of the gas refrigerant, and g (m / s 2 ) is the gravitational acceleration, and D (m) is the inner diameter of the pipe that constitutes the connecting flow path; 3. The refrigeration system of claim 2.

4. The switching permission condition is that the Froude number is 1 or more.

4. The refrigeration system of claim 3.

5. When the switching permission condition is not satisfied, the control unit drives the compressor to perform an oil purge operation in which refrigeration oil present in the connection flow path is moved downstream of the four-way switching valve.

5. The refrigeration system according to claim 1.

6. The control unit performs the oil purge operation not only when the switching permission condition is not satisfied but also at least one of immediately after starting and before stopping the refrigeration apparatus.

6. The refrigeration system of claim 5.

7. The connecting flow path has a U-shaped tube (93) protruding downward.

5. The refrigeration system according to claim 1.

8. The refrigerant is carbon dioxide.

5. The refrigeration system according to claim 1.

9. The four-way switching valve is A valve chamber (51); a valve body (52) that slides in the valve chamber; a first pilot chamber (55) formed at an end of the valve chamber; a second pilot chamber (56) formed at an end of the valve chamber opposite to the first pilot chamber; a first port (P1) formed in the valve chest for receiving the refrigerant discharged from the compressor, a second port (P2) for ejecting the refrigerant drawn into the compressor, a third port (P3) for transferring the refrigerant between the valve chest and a heat source heat exchanger, and a fourth port (P4) for transferring the refrigerant between the valve chest and a heat 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) that connects the first pilot chamber and the first pilot solenoid valve; a second flow path (82) that connects the second pilot chamber and the second pilot solenoid valve; a third flow path (83) that connects the communication passages (64) of the first pilot solenoid valve and the second pilot solenoid valve with the second port; having 5. The refrigeration system according to claim 1.

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