Refrigeration apparatus having a four-way reversing valve and a shut-off valve

Abstract

A freezing device (100) includes a refrigerant circuit (90), a control section (9), and a first shutoff valve (41). The refrigerant circuit (90) has a compressor (11), a four-way reversing valve (12), a heat source heat exchanger (13), and a utilization heat exchanger (23). The compressor (11) has a suction port (11a) that sucks in refrigerant (R) and a discharge port (11b) that discharges the refrigerant. The control section (9) switches the circulation path of the refrigerant (R) in the refrigerant circuit (90) by performing switching of the four-way reversing valve (12). The first shutoff valve (41) is disposed between the four-way reversing valve (12) and the utilization heat exchanger (23). The control section (9) closes the first shutoff valve (41) before performing switching of the four-way reversing valve (12).

Description

Technical Field

[0001] This disclosure relates to a refrigeration apparatus having a four-way reversing valve and a shut-off valve. Background Technology

[0002] The four-way reversing valve disclosed in Patent Document 1 (Japanese Patent Application Publication No. 63-015056) is installed in a refrigeration unit for switching the circulation direction of the refrigerant. Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] Among the refrigerants used in refrigeration systems, there are types where the pressure difference between the low-pressure refrigerant gas drawn into the compressor and the high-pressure refrigerant gas discharged from the compressor is large. This large pressure difference can cause a shock when switching a four-way directional valve, potentially damaging the valve.

[0005] Technical solutions adopted to solve technical problems

[0006] The first-view refrigeration unit includes a refrigerant circuit, a control unit, and a first shut-off valve. The refrigerant circuit includes a compressor, a four-way reversing valve, a heat source heat exchanger, and a utilization heat exchanger. The compressor has a refrigerant suction port and a refrigerant discharge port. The control unit switches the refrigerant circulation path in the refrigerant circuit by switching the four-way reversing valve. The first shut-off valve is located between the four-way reversing valve and the utilization heat exchanger. The control unit closes the first shut-off valve before switching the four-way reversing valve.

[0007] According to this structure, by closing the first shut-off valve before switching the four-way reversing valve, the refrigerant circuit around the four-way reversing valve is cut off. Therefore, it is possible to reduce the possibility of damage to the four-way reversing valve due to a large pressure difference in refrigerant.

[0008] The second viewpoint's refrigeration unit, based on the first viewpoint's refrigeration unit, further includes a second shut-off valve. The second shut-off valve is positioned between the four-way reversing valve and the heat source heat exchanger. The control unit also closes the second shut-off valve before switching the four-way reversing valve.

[0009] According to this structure, in addition to the first shut-off valve, the second shut-off valve also helps to cut off the refrigerant circuit around the four-way reversing valve. Therefore, it is possible to further reduce the possibility of damage to the four-way reversing valve.

[0010] The third-view refrigeration unit, based on the second-view refrigeration unit, further includes a bypass flow path and a pressure equalization valve. The bypass flow path connects the suction inlet and the discharge outlet. The pressure equalization valve is configured to open or close the bypass flow path. The control unit also opens the pressure equalization valve before switching.

[0011] According to this design, the opened equalizing valve reduces the pressure difference of the refrigerant at the suction port and discharge port. Therefore, it further reduces the likelihood of damage to the four-way reversing valve.

[0012] The fourth viewpoint's refrigeration unit is based on any of the first to third viewpoints' refrigeration units. After receiving a switching command for the four-way reversing valve, the control unit switches the four-way reversing valve after a predetermined time.

[0013] Based on this structure, the pressure difference between the refrigerant at the suction inlet and discharge outlet can be expected to be eliminated after a specified period of time. Therefore, the likelihood of damage to the four-way reversing valve can be reduced.

[0014] The refrigeration unit of the fifth viewpoint is based on the refrigeration unit of any of the first to fourth viewpoints, and the control unit stops the compressor after receiving the switching command of the four-way reversing valve.

[0015] According to this design, the compressor is stopped during switching. Therefore, a pressure difference in the refrigerant between the inlet and outlet can be avoided.

[0016] The sixth viewpoint's refrigeration unit is based on the third viewpoint's refrigeration unit. Before switching the four-way directional valve, the control unit closes the first or second shut-off valve and opens the equalizing valve. The control unit switches the four-way directional valve with the equalizing valve open. After switching the four-way directional valve, the control unit closes the equalizing valve and opens the first or second shut-off valve.

[0017] According to this structure, the equalizing valve is opened before the four-way reversing valve switches. Therefore, the pressure difference of the refrigerant at the suction port and discharge port is eliminated, thus preventing damage to the four-way reversing valve.

[0018] The seventh viewpoint's refrigeration unit, based on the third viewpoint's refrigeration unit, involves the control unit closing either the first or second shut-off valve and opening the equalizing valve before switching the four-way directional valve. The control unit closes the equalizing valve when the pressure difference between the suction inlet and discharge outlet falls below a specified value. The control unit then switches the four-way directional valve with the equalizing valve closed. After the four-way directional valve switching is complete, the control unit opens either the first or second shut-off valve.

[0019] According to this structure, the equalizing valve is closed before the four-way reversing valve is switched. Therefore, the equalizing valve can be quickly closed when it can be determined that the pressure difference of the refrigerant at the suction port and the discharge port is small enough.

[0020] The refrigeration device of the eighth viewpoint is based on the refrigeration device of any of the first to seventh viewpoints, and the refrigerant is carbon dioxide.

[0021] Based on this structure, the refrigerant is carbon dioxide. When carbon dioxide is used as the refrigerant, the switching noise of the four-way reversing valve tends to increase. Therefore, by activating the first shut-off valve, the impact during switching is less likely to be transmitted to the outside.

[0022] The refrigeration unit of the ninth viewpoint is based on the refrigeration unit of the second or third viewpoint, and further includes a heat source unit, a utilization unit, and a valve unit. The heat source unit includes a compressor, a four-way reversing valve, and a heat source heat exchanger. The utilization unit includes a utilization heat exchanger. The valve unit is located between the heat source unit and the utilization unit. A first shut-off valve or a second shut-off valve is located in the valve unit.

[0023] According to this structure, the first and second shut-off valves are configured in the valve unit. Therefore, when installing the first and second shut-off valves, there is no need to change the design of the refrigerant circuit of the heat source unit. Attached Figure Description

[0024] Figure 1 This is a circuit diagram showing the structure of the refrigeration apparatus 100 according to the first embodiment.

[0025] Figure 2 This is a cross-sectional schematic diagram showing the four-way reversing valve 12 in operation during hot and cold water utilization.

[0026] Figure 3 This is another cross-sectional schematic diagram showing the four-way directional valve 12 in the transition state.

[0027] Figure 4 This is another cross-sectional schematic diagram showing the four-way reversing valve 12 in operation during heat utilization.

[0028] Figure 5 This is a block diagram showing the electrical system of the refrigeration unit 100.

[0029] Figure 6 This is a flowchart of the switching control of the four-way directional valve 12.

[0030] Figure 7 This is a flowchart of the output processing of the switching control signal Q2.

[0031] Figure 8 This is a flowchart of the switching control of the four-way directional valve 12 in the second variation of the first embodiment.

[0032] Figure 9 This is a cross-sectional schematic diagram showing the structure of a rotary four-way directional valve 12.

[0033] Figure 10 This is a flowchart of the switching control of the four-way directional valve 12 in the third variation of the first embodiment.

[0034] Figure 11This is a circuit diagram showing the structure of the refrigeration apparatus 100 according to the second embodiment. Detailed Implementation

[0035] <First Implementation>

[0036] (1) Overall structure

[0037] Figure 1 A refrigeration apparatus 100 according to a first embodiment is shown. The refrigeration apparatus 100 is used to provide a user with hot heat or cold heat obtained from a heat source, and is configured as an air conditioning unit, for example. The refrigeration apparatus 100 is capable of performing hot / cold heat utilization operation to provide a user with hot / cold heat, and warm heat utilization operation to provide a user with warm heat. In the case that the refrigeration apparatus 100 is an air conditioning unit, these are respectively equivalent to cooling operation and heating operation.

[0038] The refrigeration unit 100 includes a heat source unit 10, multiple utilization units 20, connecting pipes 30, and a communication line 35. These components together form a refrigerant circuit 90 that circulates refrigerant R and a control unit 9 that controls the refrigerant circuit 90.

[0039] As the refrigerant R, any refrigerant can be used, such as carbon dioxide. In the following description, refrigerant R is considered to be capable of undergoing a phase change to liquid, and terms such as "condensation," "evaporation," "liquid refrigerant," and "gas-liquid two-phase refrigerant" are used in the description. However, it should be noted that in the case of refrigerant R being carbon dioxide, there is no accompanying phase change to liquid, therefore, these terms are not strictly applicable.

[0040] (1-1) Heat source unit 10

[0041] The heat source unit 10 obtains heat or cold from a heat source such as outdoor air. The heat source unit 10 includes a compressor 11, a four-way reversing valve 12, a heat source heat exchanger 13, a heat source expansion valve 15, a storage tank 16, a liquid shut-off valve 17, a gas shut-off valve 18, a first shut-off valve 41, a second shut-off valve 42, and a pressure equalization valve 43, all components of the refrigerant circuit 90. The heat source unit 10 also includes a heat source fan 14 located near the heat source heat exchanger 13. The heat source unit 10 also includes a heat source control unit 19, a component of the control unit 9. The heat source unit 10 also includes a low-pressure sensor S1 and a high-pressure sensor S2.

[0042] (1-1-1) Compressor 11

[0043] The compressor 11 has an inlet 11a and an outlet 11b. The compressor 11 compresses low-pressure gaseous refrigerant drawn in through the inlet 11a to generate high-pressure gaseous refrigerant, which is then discharged through the outlet 11b. A low-pressure sensor S1 is provided on the inlet side of the compressor 11, that is, near the inlet 11a. A high-pressure sensor S2 is provided on the outlet side of the compressor 11, that is, near the outlet 11b. Both the low-pressure sensor S1 and the high-pressure sensor S2 measure the pressure of the refrigerant R.

[0044] (1-1-2) Four-way directional valve 12

[0045] The four-way reversing valve 12 switches the circulation path of refrigerant R. The four-way reversing 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 connected to the outlet 11b. The second port P2 is connected to a pipe connected to the storage tank 16. The third port P3 is connected to a pipe connected to the heat exchanger 13. The fourth port P4 is connected to a pipe connected to the gas shut-off valve 18.

[0046] When the refrigeration unit 100 is operating in a cold and heat utilization mode, such as Figure 1 As shown by the solid line, the four-way reversing valve 12 connects the first port P1 to the third port P3, and the second port P2 to the fourth port P4. When the refrigeration unit 100 is operating under heat utilization conditions, such as... Figure 1 As shown by the dashed line, the four-way directional valve 12 connects the first port P1 to the fourth port P4, and the second port P2 to the third port P3.

[0047] (1-1-3) Heat source heat exchanger 13

[0048] The heat source heat exchanger 13 performs heat exchange between outdoor air and refrigerant R. In operation for both cooling and heating, the heat source heat exchanger 13 functions as a condenser or radiator for refrigerant R; in operation for both warm and warm heating, it functions as an evaporator or absorber for refrigerant R.

[0049] (1-1-4) Heat source fan 14

[0050] The heat source fan 14 promotes heat exchange in the heat source heat exchanger 13 by moving outdoor air through the interior of the heat source heat exchanger 13.

[0051] (1-1-5) Heat source expansion valve 15

[0052] The heat source expansion valve 15 reduces the pressure of refrigerant R and regulates the flow rate of refrigerant R.

[0053] (1-1-6) Storage tank 16

[0054] Storage tank 16 stores the liquid refrigerant component mixed with the gaseous refrigerant and allows the gaseous refrigerant to pass through. Storage tank 16 is connected to the suction port 11a of compressor 11. Storage tank 16 prevents liquid refrigerant from being drawn into compressor 11.

[0055] (1-1-7) Liquid shut-off valve 17

[0056] The liquid shut-off valve 17 allows or interrupts the flow of liquid refrigerant or two-phase refrigerant. The opening and closing of the liquid shut-off valve 17 can be performed manually, for example, by the installation personnel of the refrigeration unit 100.

[0057] (1-1-8) Gas shut-off valve 18

[0058] The gas shut-off valve 18 allows or blocks the flow of low-pressure or high-pressure refrigerant. The opening and closing of the gas shut-off valve 18 is, for example, manually performed by the installation personnel of the refrigeration unit 100.

[0059] (1-1-9) First shut-off valve 41

[0060] The first shut-off valve 41 is controlled by the control unit 9 to allow or cut off the refrigerant R. The first shut-off valve 41 is disposed between the four-way reversing valve 12 and the heat exchanger 23 described later. Specifically, the first shut-off valve 41 is disposed between the fourth port P4 of the four-way reversing valve 12 and the gas shut-off valve 18.

[0061] (1-1-10) Second shut-off valve 42

[0062] The second shut-off valve 42 is controlled by the control unit 9 to allow or cut off the refrigerant R. The second shut-off valve 42 is located between the third port P3 of the four-way reversing valve 12 and the heat source heat exchanger 13.

[0063] (1-1-11) Pressure equalizing valve 43

[0064] The pressure equalizing valve 43 is controlled by the control unit 9 to allow or cut off the refrigerant R. The pressure equalizing valve 43 is disposed in a bypass flow path 95 that connects the suction port 11a and the discharge port 11b and bypasses the compressor 11. The pressure equalizing valve 43 reduces the pressure difference of the refrigerant at the suction port 11a and the discharge port 11b by opening.

[0065] (1-1-12) Heat source control unit 19

[0066] The heat source control unit 19 acquires measured data from the low-pressure sensor S1 and the high-pressure sensor S2. The heat source control unit 19 also controls the compressor 11, the four-way reversing valve 12, the heat source fan 14, the heat source expansion valve 15, the first shut-off valve 41, the second shut-off valve 42, and the pressure equalization valve 43.

[0067] (1-2) Using Unit 20

[0068] The multiple utilization units 20 have substantially the same structure. Hereinafter, one of the multiple utilization units 20 will be described.

[0069] The refrigerant unit 20 provides heat or cold to the user. As a component of the refrigerant circuit 90, the refrigerant unit 20 includes an expansion valve 22 and a heat exchanger 23. The refrigerant unit 20 also includes a fan 24 located near the heat exchanger 23. The refrigerant unit 20 further includes a control unit 29, which is a component of the control unit 9. A remote control 27 is wired or wirelessly connected to the control unit 29.

[0070] (1-2-1) Using expansion valve 22

[0071] The pressure of refrigerant R is reduced by expansion valve 22, and the flow rate of refrigerant R is adjusted.

[0072] (1-2-2) Using heat exchanger 23

[0073] Heat exchanger 23 is used for heat exchange between indoor air and refrigerant R. In the case of cold and hot utilization operation, heat exchanger 23 functions as an evaporator or heat absorber for refrigerant R, and in the case of warm and hot utilization operation, it functions as a condenser or heat radiator for refrigerant R.

[0074] (1-2-3) Using fan 24

[0075] The fan 24 promotes heat exchange in the heat exchanger 23 by moving indoor air through its interior. The fan 24 also delivers the conditioned air from the heat exchanger 23 to the vicinity of the user.

[0076] (1-2-4) Using the control unit 29

[0077] The control unit 29 acquires measured data from a sensor not shown. The control unit 29 also controls the expansion valve 22 and the fan 24. Furthermore, the control unit 29 communicates with the heat source control unit 19, together forming a control unit 9. The control unit 29 also communicates with the remote controller 27.

[0078] (1-2-5) Remote Control 27

[0079] Remote controller 27 receives commands from the user and provides information to the user. The commands from the user include setting the target temperature, setting the airflow, and executing and switching between hot and cold operation and warm / hot operation.

[0080] (1-3) Connecting piping 30

[0081] The connecting piping 30 connects the heat source unit 10 to the utilization unit 20 to form a refrigerant circuit 90. The connecting piping 30 has a liquid connecting piping 31 and a gas connecting piping 32.

[0082] (1-3-1) Liquid connection piping 31

[0083] The liquid connecting pipe 31 connects the liquid shut-off valve 17 to the heat exchanger 23, allowing the liquid refrigerant or gas-liquid two-phase refrigerant to move.

[0084] (1-3-2) Gas connection piping 32

[0085] Gas connection piping 32 connects gas shut-off valve 18 and heat exchanger 23 to move low-pressure gas refrigerant or high-pressure gas refrigerant.

[0086] (1-4) Communication line 35

[0087] Communication line 35 connects heat source control unit 19 and utilization control unit 29 to form control unit 9. Communication line 35 transmits control signals, status, data and other signals between heat source control unit 19 and utilization control unit 29.

[0088] (2) Structure of the four-way reversing valve 12

[0089] Figure 2 The detailed structure of the four-way directional valve 12 is shown. The four-way directional valve 12 is a differential pressure driven type. The four-way directional valve 12 has a main valve section 50, a pilot valve section 60, and a small-diameter pipe assembly section 80.

[0090] (2-1) Main valve section 50

[0091] The main valve section 50 determines the circulation direction of the refrigerant R. The main valve section 50 includes a housing 51, a valve core 52, a first piston 53, and a second piston 54.

[0092] (2-1-1) Shell 51

[0093] The housing 51 is a cylindrical metal tube. The internal space of the housing 51 forms a valve chamber 51a. Four tubes, constituting a first port P1, a second port P2, a third port P3, and a fourth port P4, are connected to the housing 51. The fourth port P4, the second port P2, and the third port P3 are arranged in a row along the length of the housing 51. Furthermore, the first port P1 is located in a position not aligned with the other ports. The valve chamber 51a is filled with high-pressure gaseous refrigerant introduced through the first port P1.

[0094] (2-1-2) Valve core 52

[0095] The valve core 52 is a sliding component within the valve chamber 51a. The valve core 52 has: an arched 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 core 52 can... Figure 2 Move left and right in the middle.

[0096] (2-1-3) First piston 53

[0097] The first piston 53 is fixed to the first connecting part 52b and moves together with the valve core 52. The first piston 53 forms a first pilot chamber 55 between the left end of the valve chamber 51a and the housing 51. A first piston hole 53a with a small diameter is formed on the first piston 53. The first pilot chamber 55 communicates with the first port P1 through the first piston hole 53a.

[0098] (2-1-4) Second piston 54

[0099] The second piston 54 is fixed to the second connecting part 52c and moves together with the valve core 52. The second piston 54 forms a second pilot chamber 56 between the right end of the valve chamber 51a and the housing 51. A second piston hole 54a with a smaller diameter is formed on the second piston 54. The second pilot chamber 56 communicates with the second port P2 through the second piston hole 54a.

[0100] (2-2) Pilot valve section 60

[0101] The pilot valve section 60 regulates the pressure inside the first pilot chamber 55 and the second pilot chamber 56 by controlling the refrigerant R moving into the first pilot chamber 55 and the second pilot chamber 56. The pilot valve section 60 includes a first pilot solenoid valve 61, a second pilot solenoid valve 62, and a connecting section 63.

[0102] (2-2-1) First pilot solenoid valve 61

[0103] The first pilot solenoid valve 61 controls whether the refrigerant R at the second port P2 reaches the first pilot chamber 55. The first pilot solenoid valve 61 has a first pilot valve core 71, a first cylinder 72, a first coil 73, and a first spring 74.

[0104] The first pilot valve core 71 is disposed inside the first cylinder 72, and can... Figure 2 The first pilot valve 71a is formed at the right end of the first pilot valve core 71. The restoring force of the first spring 74 acts to move the first pilot valve core 71 to the right. When current flows through the first coil 73, the first pilot valve core 71 is attracted by the first coil 73 to resist the restoring force of the first spring 74, and thus moves to the left.

[0105] (2-2-2) Second pilot solenoid valve 62

[0106] The second pilot solenoid valve 62 controls whether the refrigerant R at the second port P2 reaches the second pilot chamber 56. The second pilot solenoid valve 62 has a second pilot valve core 75, a second cylinder 76, a second coil 77, and a second spring 78.

[0107] The second pilot valve core 75 is disposed in the second cylinder 76, and can be used to... Figure 2 The second pilot valve 75a is formed at the left end of the second pilot valve core 75. The restoring force of the second spring 78 causes the second pilot valve core 75 to move to the left. When current flows through the second coil 77, the second pilot valve core 75 is attracted by the second coil 77 to resist the restoring force of the second spring 78, and thus moves to the right.

[0108] (2-2-3) Connecting part 63

[0109] The connecting part 63 is a component 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 connecting passage 64, a first connection port 67, a second connection port 68, and a third connection port 69.

[0110] The first pilot valve seat 65 receives the first pilot valve 71a. The first pilot valve seat 65 is connected to the first connection port 67. The first pilot solenoid valve 61 is closed when the first pilot valve 71a is in contact with the first pilot valve seat 65. At this time, the first connection port 67 is blocked by the first pilot valve 71a. The first pilot solenoid valve 61 is open when the first pilot valve 71a is separated from the first pilot valve seat 65. At this time, the first connection port 67 is opened.

[0111] The second pilot valve seat 66 receives the second pilot valve 75a. The second pilot valve seat 66 is connected to the second connection port 68. The second pilot solenoid valve 62 is closed when the second pilot valve 75a is in contact with the second pilot valve seat 66. At this time, the second connection port 68 is blocked by the second pilot valve 75a. The second pilot solenoid valve 62 is open when the second pilot valve 75a is separated from the second pilot valve seat 66. At this time, the second connection port 68 is opened.

[0112] The connecting path 64 connects the first pilot valve seat 65 and the second pilot valve seat 66. A third connection port 69 is formed on the connecting path 64. When the first pilot solenoid valve 61 is open, the first connection port 67 and the third connection port 69 are connected via the connecting path 64. When the second pilot solenoid valve 62 is open, the second connection port 68 and the third connection port 69 are connected via the connecting path 64.

[0113] (2-3) Small diameter pipe assembly 80

[0114] The narrow-diameter tube assembly 80 is an assembly of capillary tubes, having 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 to the first connection port 67. The second flow path 82 connects the second pilot chamber 56 to the second connection port 68. The third flow path 83 connects the second port P2 to the third connection port 69.

[0115] (3) Operation of the four-way directional valve 12

[0116] (3-1) Operating status of heating and cooling

[0117] Figure 2 The configuration of the various parts of the four-way directional valve 12 for hot and cold operation is shown. The valve core 52 is located on the left side. Thus, the valve core 52 connects the second port to the fourth port and connects the first port to the third port.

[0118] To position the valve core 52 on the left, the first pilot solenoid valve 61 is opened, and the second pilot solenoid valve 62 is closed. Thus, the second port P2 is connected to the first pilot chamber 55 via the third flow path 83, the third connection port 69, the connecting path 64, the first connection port 67, and the first flow path 81. Because the pressure of the gaseous refrigerant present in the second port P2 is low, the refrigerant R in the first pilot chamber 55 can be drawn to the second port P2. Furthermore, because the diameter of the first piston orifice 53a is small, the refrigerant R on both sides of the first piston will not immediately achieve equal pressure.

[0119] 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 gaseous refrigerant flowing in from the second piston hole 54a.

[0120] Under the pressure difference between the low-pressure refrigerant in the first pilot chamber 55 and the high-pressure refrigerant in the second pilot chamber 56, a force acts on the valve core 52 to move to the left. Therefore, the valve core 52 can be stably positioned on the left side.

[0121] (3-2) Transition state

[0122] Figure 3 The diagram illustrates the transition state of the four-way directional valve 12 when switching from cold / hot operation to warm / hot operation. To switch the four-way directional 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 is connected to the second pilot chamber 56 via the third flow path 83, the third connection port 69, the connecting path 64, the second connection port 68, and the second flow path 82. High-pressure gaseous refrigerant in the second pilot chamber 56 can be drawn to the second port P2.

[0123] 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 gradually filled with high-pressure gaseous refrigerant flowing in from the first piston hole 53a.

[0124] When the pressure of the gaseous refrigerant in the first pilot chamber 55 becomes greater than the pressure of the gaseous refrigerant in the second pilot chamber 56, a force that causes the valve core 52 to move to the right is applied to the valve core 52.

[0125] (3-3) The operating status of heat utilization

[0126] Figure 4 This refers to the configuration of the various parts of the four-way directional valve during heat recovery operation. Figure 3 Similarly, in the transition state, the first pilot solenoid valve 61 is closed, and the second pilot solenoid valve 62 is opened. The valve core 52 on the right connects the second port to the third port and the first port to the fourth port.

[0127] Under the pressure difference between the high-pressure refrigerant in the first pilot chamber 55 and the low-pressure refrigerant in the second pilot chamber 56, a force acts on the valve core 52 to move it to the right. Therefore, the valve core 52 can be stably positioned on the right side.

[0128] To resume cooling and heating operation, control is applied to open the first pilot solenoid valve 61 and close the second pilot solenoid valve 62. This, by filling the first pilot chamber 55 with low-pressure refrigerant and the second pilot chamber 56 with high-pressure refrigerant, generates a force that moves the valve core 52 to the left.

[0129] (4) Control of the four-way directional valve 12

[0130] (4-1) Electrical system of refrigeration unit 100

[0131] Figure 5 The electrical system of the refrigeration unit 100 is shown. Measurement data from the low-pressure sensor S1 and the high-pressure sensor S2, as well as user commands sent from the remote controllers 27 of each of the multiple utilization units 20, are input to the control unit 9. Furthermore, the control unit 9 outputs control signals for the compressor 11, the four-way reversing valve 12, the heat source fan 14, the heat source expansion valve 15, and the expansion valve 22 and fan 24 belonging to each of the multiple utilization units 20.

[0132] The commands sent from the remote controller 27 include a switching command Q1 for the four-way reversing valve 12. For example, when the refrigeration unit 100 is operating in both heating and cooling mode, if the user inputs a command to the remote controller 27 indicating that heating and cooling mode should be operated, the remote controller 27 sends a switching command Q1 to the control unit 9 indicating that the four-way reversing valve 12 should be switched to operate in both heating and cooling mode. Alternatively, when the refrigeration unit 100 is operating in both heating and cooling mode, if the user inputs a command to the remote controller 27 indicating that heating and cooling mode should be operated, the remote controller 27 sends a switching command Q1 to the control unit 9 indicating that the four-way reversing valve 12 should be switched to operate in both heating and cooling mode.

[0133] When the control unit 9 receives the switching command Q1, it performs a predetermined calculation and outputs a switching control signal Q2 for the four-way directional valve 12. Specifically, the switching control signal Q2 refers to the opening and closing control signal for the first pilot solenoid valve 61 and the second pilot solenoid valve 62.

[0134] (4-2) Switching control

[0135] Figure 6 This is a flowchart of the main routine for the switching control of the four-way directional valve 12. In step S100, the switching control begins.

[0136] In step S101, it is checked whether the refrigerant circuit 90 has achieved its normal state, with the first shut-off valve 41 and the second shut-off valve 42 open and the equalizing valve 43 closed. If the normal state has not been achieved (S101: No), the error handling process proceeds to step S191. On the other hand, if the normal state has been achieved (S101: Yes), the process proceeds to step S102.

[0137] In step S102, it is confirmed whether the control unit 9 has received the switching command Q1. If the switching command Q1 is not received (S102: No), the process proceeds to step S191 for error handling. On the other hand, if the switching command Q1 is received (S102: Yes), the process proceeds to step S103.

[0138] In step S103, the control unit 9 stops the compressor 11. In step S104, the control unit 9 closes the first shut-off valve 41 and the second shut-off valve 42, and opens the equalizing valve 43. This prepares the refrigerant circuit 90 for switching the four-way reversing valve 12.

[0139] In step S111, the count value of the timer in control unit 9 is reset to zero. In step S112, control unit 9 starts the timer. In step S113, control unit 9 checks the timer's count value to confirm whether a predetermined time has elapsed. The predetermined time is, for example, 5 seconds. If the predetermined time has not elapsed (S113: No), the process returns to step S113. On the other hand, if the predetermined time has elapsed (S113: Yes), the process proceeds to step S114. In step S114, control unit 9 stops the timer. Thus, after the predetermined time has elapsed following preparation for switching the refrigerant circuit 90 of the four-way reversing valve 12, the state of the refrigerant R can be expected to stabilize.

[0140] In step S121, the control unit 9 closes the pressure equalization valve 43.

[0141] In step S131, the control unit 9 executes a subroutine for outputting a switching control signal Q2 to the four-way directional valve 12. The subroutine for outputting the switching control signal Q2 will be described later.

[0142] After the switching control of the four-way reversing valve 12 is completed, in step S141, the control unit 9 restores the connection of the refrigerant circuit 90 other than the four-way reversing valve 12 to its original state by opening the first shut-off valve 41 and the second shut-off valve 42. Then, in step S142, the control unit 9 restarts the operation of the compressor 11.

[0143] Then, in step S114, the main routine for switching control of the four-way directional valve 12 ends.

[0144] Step S191 is error handling. In this step, the control unit 9 restores the refrigerant circuit 90 to its normal state by opening the first shut-off valve 41 and the second shut-off valve and closing the equalizing valve 43. In step S192, the control unit 9 terminates the main routine of the switching control due to an error.

[0145] Figure 7 This is a flowchart of a subroutine for processing the output of the switching control signal Q2. In step S200, the output of the switching control signal Q2 begins. In step S201, the control unit 9 confirms the content of the received switching command Q1. If the content of the switching command Q1 requests the execution of a cooling / heating utilization operation (step S201: Cooling / Heating Utilization Operation), the process proceeds to step S202. In step S202, the control unit 9 outputs the switching control signal Q2, indicating that the first pilot solenoid valve 61 is opened and the second pilot solenoid valve 62 is closed. Then, in step S204, the output processing of the switching control signal Q2 ends.

[0146] On the other hand, if the switching instruction Q1 requests the execution of heat utilization operation (step S201: heat utilization operation), the process proceeds to step S203. In step S203, the control unit 9 outputs a switching control signal Q2 indicating that the first pilot solenoid valve 61 is closed and the second pilot solenoid valve 62 is opened. Then, in step S204, the output processing of the switching control signal Q2 ends.

[0147] (5) Characteristics

[0148] (5-1)

[0149] By closing the first shut-off valve 41 and the second shut-off valve 42 before switching the four-way reversing valve 12, the refrigerant circuit 90 around the four-way reversing valve 12 is cut off. Therefore, the possibility of damage to the four-way reversing valve 12 due to a large pressure difference of refrigerant R can be reduced.

[0150] (5-2)

[0151] By opening the equalizing valve 43, the pressure difference of the refrigerant R at the suction port 11a and the discharge port 11b is reduced. Therefore, the possibility of damage to the four-way reversing valve 12 can be further reduced.

[0152] (5-3)

[0153] After receiving the switching command Q1 from the four-way reversing valve, the control unit 9 switches the four-way reversing valve 12 after a predetermined time. Therefore, as the predetermined time passes, it can be expected that the pressure difference of the refrigerant R at the suction port 11a and the discharge port 11b will be eliminated, thus reducing the possibility of damage to the four-way reversing valve 12.

[0154] (5-4)

[0155] After receiving the switching command Q1 from the four-way reversing valve 12, the control unit 9 stops the compressor 11 in step S103. Therefore, it is possible to avoid the generation of a pressure difference of refrigerant R at the suction port 11a and the discharge port 11b.

[0156] (5-5)

[0157] Before switching the four-way reversing valve 12 in step S131, the pressure equalization valve 43 is closed in step S121. Therefore, when it can be determined that the pressure difference of the refrigerant R at the suction port 11a and the discharge port 11b is sufficiently small, the pressure equalization valve 43 can be closed quickly.

[0158] In particular, in the four-way directional valve 12 Figures 2-4 In the case of differential pressure driven valve 43 shown, if the pressure difference is reduced to a certain extent by equalization, the equalization valve 43 can be closed even before the four-way directional valve 12 is switched.

[0159] (5-6)

[0160] The refrigerant R can be carbon dioxide. When carbon dioxide is used as the refrigerant, the switching noise of the four-way reversing valve 12 tends to increase. Therefore, by closing the first shut-off valve 41 and the second shut-off valve 42, the impact during the switching of the four-way reversing valve 12 is less likely to be transmitted to the outside.

[0161] (6) Variations

[0162] (6-1) First variation

[0163] In the aforementioned embodiment, the control unit 9 closes both the first shut-off valve 41 and the second shut-off valve 42 before the switching action of the four-way directional valve 12. Alternatively, the control unit 9 may close only either the first shut-off valve 41 or the second shut-off valve 42 before the switching action of the four-way directional valve 12.

[0164] (6-2) Second variation

[0165] In the aforementioned embodiments, such as Figure 6 As shown, after receiving the switching command Q1 from the four-way reversing valve 12, the control unit 9 switches the four-way reversing valve 12 after a predetermined time. Alternatively, after receiving the switching command Q1 from the four-way reversing valve 12, the control unit 9 may calculate the pressure difference of the refrigerant R on the suction side and discharge side of the compressor 11 based on the measured values ​​of the low-pressure sensor S1 and the high-pressure sensor S2, and then switch the four-way reversing valve 12 after confirming that the pressure difference is small.

[0166] Figure 8 This is a flowchart of the main routine for the switching control of the four-way directional valve 12 in the second variation. In step S302, it is confirmed whether the control unit 9 has received the switching command Q1. Then, in step S304, the control unit 9 opens the equalizing valve 43. In step S313, the control unit 9 calculates the pressure difference between the high-pressure side and the low-pressure side based on the measured values ​​of the low-pressure sensor S1 and the high-pressure sensor S2, and confirms whether the pressure difference is less than a predetermined value. If the pressure difference is not less than the predetermined value (S313: No) and a predetermined time has elapsed (S314: Yes), the process proceeds to step S391 for error handling. On the other hand, if the pressure difference is less than the predetermined value (S313: Yes), the process proceeds to step S331 via steps S316 and S321. In step S331, the four-way directional valve 12 is switched.

[0167] (6-3) Third variation

[0168] In the aforementioned embodiment, the four-way directional valve 12 is Figures 2-4 The differential pressure driven type is shown. Alternatively, the four-way directional valve 12 can also be rotary.

[0169] Figure 9 The rotary four-way directional valve 12 shown has a cylindrical housing 251 and a valve seat 255 disposed on the bottom surface of the housing 251. The valve seat 255 has a first port P1, a second port P2, a third port P3, and a fourth port P4 for refrigerant R to pass through. Within the housing 251, a cylindrical valve core 252 is configured to rotate. The valve core 252 has a high-pressure side groove 252a and a low-pressure side groove 252b. The valve core 252 can rotate 90° under the action of a coil and a permanent magnet (not shown). Figure 9 In the process, the first port P1 is connected to the third port P3, and the second port P2 is connected to the fourth port P4. In valve core 252 from... Figure 9 When the state is rotated by 90°, the first port P1 can be connected to the fourth port P4, and the second port P2 can be connected to the third port P3.

[0170] Figure 10 This is the flowchart of the main routine for the switching control of the rotary four-way directional valve 12. Figure 6 The control of the differential pressure driven four-way directional valve 12 is different, in Figure 10 In the control of the rotary four-way directional valve 12, when the four-way directional valve 12 is switched in step S431, the pressure equalization valve 43 is opened.

[0171] Specifically, before switching the four-way directional valve 12, the control unit 9 closes the first flow-stopping valve 41 and the second flow-stopping valve 42 in step S404, and opens the pressure equalization valve 43. Next, in step S431, the control unit 9 switches the four-way directional valve 12 while the pressure equalization valve 43 is open. In step S441, after the switching of the four-way directional valve 12 is completed, the control unit 9 closes the pressure equalization valve 43 and opens the first flow-stopping valve 41 and the second flow-stopping valve 42.

[0172] The rotary four-way directional valve 12 is difficult to switch when there is a large pressure difference between the high-pressure side and the low-pressure side. Therefore, it is sometimes desirable to switch the four-way directional valve 12 while the equalizing valve 43 is reliably open.

[0173] <Second Implementation>

[0174] (1) Structure

[0175] Figure 11A refrigeration apparatus 100 according to a second embodiment is shown. The refrigeration apparatus 100 differs from the first embodiment in that each of the multiple utilization units 20 can be individually selected for either cold / hot utilization operation or warm / hot utilization operation. To achieve this individual selection, the connecting piping 30 includes three pipes: a liquid connecting piping 31, a low-pressure gas connecting piping 32, and a high-pressure / low-pressure gas connecting piping 33. Furthermore, the heat source unit 10 includes two four-way directional valves: a first four-way directional valve 12a and a second four-way directional valve 12b, and two gas shut-off valves: a first gas shut-off valve 18a and a second gas shut-off valve 18b. Additionally, a valve unit 40 is arranged between the heat source unit 10 and each utilization unit 20.

[0176] Each valve unit 40 has two first shut-off valves 41 and a valve control unit 49. Of the two first shut-off valves 41, one allows refrigerant R to pass through or cut off between the low-pressure gas connecting pipe 32 and the heat exchanger 23, and the other allows refrigerant R to pass through or cut off between the high-pressure and low-pressure gas connecting pipe 33 and the heat exchanger 23. The valve control unit 49, together with the heat source control unit 19 and the utilization control unit 29, constitutes the control unit 9 of the refrigeration unit 100.

[0177] (2) Characteristics

[0178] When a switching command Q1 for the first four-way reversing valve 12a or the second four-way reversing valve 12b is issued from the remote controller 27 of any of the utilization units 20, the control unit 9, before the switching operation is performed, closes both first shut-off valves 41 included in each valve unit 40, in the same manner as in the first embodiment. This reduces the likelihood of damage to the first four-way reversing valve 12a or the second four-way reversing valve 12b due to pressure differences in the refrigerant R.

[0179] (3) Variations

[0180] In the above embodiment, the second shut-off valve 42 is disposed in the heat source unit 10. Alternatively, the piping of the refrigerant circuit 90 may be designed such that the second shut-off valve 42 is disposed in the valve unit 40.

[0181] <Conclusion>

[0182] The embodiments of this disclosure have been described above, but it should be understood that various changes in form and detail can be made without departing from the spirit and scope of this disclosure as set forth in the claims.

[0183] Symbol Explanation

[0184] 9. Control Department; 10 Heat source units; 11. Compressor; 11a Inlet; 11b Discharge outlet; 12. Four-way directional valve; 13. Heat source heat exchanger; 19. Heat Source Control Department; 20. Utilization Unit; 23. Utilize heat exchangers; 27. Remote control; 29. Utilize the control unit; 30 Connecting piping; 35. Communication lines; 40 Valve Units; 41 First shut-off valve; 42 Second shut-off valve; 43. Pressure equalizing valve; 49 Valve control unit; 90. Refrigerant circuit; 95. Bypass flow path; 100 Refrigeration unit; Q1 Switching command; Q2 switches the control signal; R is the refrigerant.

[0185] Existing technical documents

[0186] Patent documents

[0187] Patent Document 1: Japanese Patent Application Publication No. 63-015056

Claims

1. A refrigeration apparatus (100), characterized in that, include: The compressor (11) has an inlet (11a) for drawing in refrigerant (R) and an outlet (11b) for discharging the refrigerant. A refrigerant circuit (90) having a four-way reversing valve (12), a heat source heat exchanger (13), and a heat exchanger (23). Control unit (9), which switches the refrigerant circulation path in the refrigerant circuit by switching the four-way reversing valve; and A first shut-off valve (41) is disposed between the four-way reversing valve and the heat exchanger. Before switching the four-way directional valve, the control unit closes the first flow-stopping valve.

2. The refrigeration apparatus according to claim 1, characterized in that, The refrigeration unit further includes a second shut-off valve (42), which is disposed between the four-way reversing valve and the heat source heat exchanger. Before switching the four-way directional valve, the control unit also closes the second flow-stop valve.

3. The refrigeration apparatus according to claim 2, characterized in that, Also includes: A bypass flow path (95) connects the inlet and the outlet; as well as The pressure equalization valve (43) is configured to open or close the bypass flow path. The control unit also opens the pressure equalization valve before performing the switching.

4. The refrigeration apparatus according to any one of claims 1 to 3, characterized in that, After receiving the switching command (Q1) of the four-way directional valve, the control unit performs the switching of the four-way directional valve after a specified time.

5. The refrigeration apparatus according to any one of claims 1 to 4, characterized in that, Upon receiving the switching command (Q1) from the four-way reversing valve, the control unit stops the compressor.

6. The refrigeration apparatus according to claim 3, characterized in that, Before switching the four-way directional valve, the control unit closes the first or second flow-stop valve and opens the pressure equalization valve. The control unit switches the four-way directional valve when the pressure equalizing valve is open. After the switching of the four-way directional valve is completed, the control unit closes the pressure equalization valve and opens the first flow cut-off valve or the second flow cut-off valve.

7. The refrigeration apparatus according to claim 3, characterized in that, Before switching the four-way directional valve, the control unit closes the first or second flow-stop valve and opens the pressure equalization valve. The control unit closes the pressure equalization valve when the pressure difference between the inlet and outlet reaches a predetermined value or below. The control unit switches the four-way directional valve when the pressure equalizing valve is closed. After the switching of the four-way reversing valve is completed, the control unit opens the first flow interruption valve or the second flow interruption valve.

8. The refrigeration apparatus according to any one of claims 1 to 7, characterized in that, The refrigerant is carbon dioxide.

9. The refrigeration apparatus according to claim 2 or 3, characterized in that, Also includes: Heat source unit (10), the heat source unit having the compressor, the four-way reversing valve and the heat source heat exchanger; Utilization unit (20), the utilization unit having the utilization heat exchanger; as well as Valve unit (40), the valve unit being disposed between the heat source unit and the utilization unit, The first or the second flow-stopping valve is disposed in the valve unit.

Images