Refrigerator

Abstract

To reduce the risk of leakage of a high-pressure refrigerant into the indoor space when the refrigerant is present on the indoor side.SOLUTION: In an air conditioner 100, after operation is stopped, the position of a valve body is maintained at a first position or moved to the first position. As a result, the refrigerant pressure inside an indoor heat exchanger decreases immediately after the stop of operation, even if the pressure was high immediately before the stop of operation. Therefore, the refrigerant pressure inside the indoor heat exchanger is not maintained at a high level during the stop, thus preventing an operation that could lead to refrigerant leakage.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This invention relates to a refrigeration system using a vapor compression refrigeration cycle. [Background technology]

[0002] In refrigeration equipment such as a heating and cooling air conditioner, the circulation direction of the refrigerant is switched between cooling and heating operation via a four-way selector valve in the refrigerant circuit. For example, in a pilot solenoid valve type four-way selector valve disclosed in Patent Document 1 (JP Patent Publication No. 11-294607), when the pilot solenoid valve is in an energized state, the valve element inside the four-way selector valve moves against spring force to switch to either the heating operation cycle or the cooling operation cycle, and when the pilot solenoid valve is in a de-energized state, the valve element returns due to spring force to switch to either the cooling operation cycle or the heating operation cycle. Summary of the Invention [Problem to be solved by the invention]

[0003] In recent years, a wide variety of refrigerants are used in the refrigerant circuits of refrigeration equipment, and when the refrigerant circuit is filled with, for example, a mildly flammable refrigerant, a flammable refrigerant, or CO2, safety measures are required to prevent leakage into the room. In particular, in heating operation cycles in which heat is dissipated to a high-pressure refrigerant in the indoor unit, attention must also be paid to safety after heating operation is stopped.

[0004] Therefore, there is a problem of reducing the risk of refrigerant leakage into the room when the high pressure refrigerant is on the indoor side. [Means for solving the problem]

[0005] A refrigeration apparatus according to a first aspect is a refrigeration apparatus in which a refrigerant circulates through a refrigerant circuit including a compressor, a four-way switching valve, a first heat exchanger, an expansion valve, and a second heat exchanger, and a refrigeration cycle operation is performed, the four-way switching valve including a flow path switching valve unit and a pilot valve unit. The flow path switching valve unit has a valve element movable between a first position and a second position different from the first position. The pilot valve unit moves the valve element. The pilot valve unit includes a first pilot valve unit and a second pilot valve unit. When the valve element is in the first position, the refrigeration cycle operation is a cooling operation in which refrigerant discharged from the compressor is sent to the first heat exchanger via the four-way switching valve. When the valve element is in the second position, the refrigeration cycle operation is a heating operation in which refrigerant discharged from the compressor is sent to the second heat exchanger via the four-way switching valve. When the refrigeration cycle operation is stopped, the valve element is maintained in the first position or moved to the first position after the operation is stopped.

[0006] In this refrigeration device, the position of the valve body after operation is stopped is maintained at the first position or moved to the first position, so that even if the refrigerant pressure in the second heat exchanger is high immediately before operation is stopped, it decreases immediately after operation is stopped.Therefore, the refrigerant pressure in the second heat exchanger is not maintained at high pressure during operation stoppage, and behavior that promotes refrigerant leakage is suppressed.

[0007] A refrigeration apparatus of a second aspect is a refrigeration apparatus of the first aspect, wherein when the valve body is in the first position, the first pilot valve section is in an open state and the second pilot valve section is in a closed state, or both the first pilot valve section and the second pilot valve section are in a closed state.

[0008] In this refrigeration system, the position of the valve element is maintained or the valve element is moved by a combination of opening and closing the first pilot valve section and opening and closing the second pilot valve section, making control easy.

[0009] A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the first or second aspect, wherein the first pilot valve section and the second pilot valve section are electromagnetic on-off valves, and the on-off state of the on-off valves is switched by switching the energized state.

[0010] In this refrigeration system, the first pilot valve unit and the second pilot valve unit can be switched between an open state and a closed state by energizing or de-energizing them, so the valve body can be operated more quickly than a motor-driven valve.

[0011] A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the third aspect, further comprising a control unit that controls the four-way selector valve. The first pilot valve unit and the second pilot valve unit are each closed when de-energized and open when energized. When a command to stop the refrigeration cycle operation is received, the control unit maintains the position of the valve element at the first position, then moves the valve element to the first position, and then closes the first pilot valve unit and the second pilot valve unit.

[0012] In this refrigeration device, closing the first pilot valve section and the second pilot valve section after the valve body has moved means that both the first pilot valve section and the second pilot valve section are in a non-energized state, thereby reducing power consumption.

[0013] A refrigeration device of a fifth aspect is the refrigeration device of the fourth aspect, wherein when a command to stop refrigeration cycle operation is received, if the valve element is in the second position or a third position between the first position and the second position, the control unit moves the valve element to the first position.

[0014] In this refrigeration device, the control unit maintains the position of the valve body in the first position after operation is stopped or moves it to the first position, so that even if the refrigerant pressure in the second heat exchanger is high immediately before operation is stopped, it decreases immediately after operation is stopped.This prevents the refrigerant pressure in the second heat exchanger from remaining high during operation stoppage, and suppresses behavior that could promote refrigerant leakage.

[0015] A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to the fourth or fifth aspect, wherein when the control unit sets the position of the valve element to the first position, the control unit sets the first pilot valve unit to an open state and the second pilot valve unit to a closed state.

[0016] In this refrigeration system, the valve element is moved by a combination of opening and closing the first pilot valve section and opening and closing the second pilot valve section, making control easy.

[0017] A refrigeration device of a seventh aspect is the refrigeration device of the fourth aspect, wherein the control unit closes the first pilot valve unit if the position of the valve body is in the first position and the first pilot valve unit is in the open state when a command to stop the refrigeration cycle operation is received.

[0018] In this refrigeration device, closing the first pilot valve unit means de-energizing the first pilot valve unit, and since both the first pilot valve unit and the second pilot valve unit are de-energized, power consumption is reduced.

[0019] The refrigeration device of an eighth aspect is the refrigeration device of the fourth aspect, wherein the control unit maintains the valve element in the first position or moves it to the first position when the difference between the temperature of the air-conditioned space and the set temperature falls within a predetermined range and the compressor is stopped.

[0020] In this refrigeration system, if the difference between the temperature of the air-conditioned space and the set temperature falls within a predetermined range during heating operation and the valve disc is maintained in the second position even after the compressor stops, the refrigerant pressure in the second heat exchanger remains high.Then, the next time the compressor starts, the refrigerant pressure in the second heat exchanger quickly rises and reaches the set temperature, causing the compressor to stop.

[0021] Such repeated starting and stopping of the compressor can cause a malfunction, so after the difference between the temperature of the air-conditioned space and the set temperature during heating operation falls within a specified range and the compressor stops, the valve body is moved to the first position to reduce the refrigerant pressure in the second heat exchanger, thereby suppressing repeated starting and stopping of the compressor.

[0022] A ninth aspect of the refrigeration apparatus is the refrigeration apparatus of any one of the second aspect to the eighth aspect, wherein the flow path switching valve unit further has a high-pressure refrigerant inlet port, a low-pressure refrigerant outlet port, a first pilot chamber, and a second pilot chamber. The high-pressure refrigerant inlet port introduces high-pressure refrigerant from the high-pressure side of the compressor. The low-pressure refrigerant outlet port guides the inflowing low-pressure refrigerant to the low-pressure side of the compressor. The first pilot chamber communicates with the first pilot valve unit. The second pilot chamber communicates with the second pilot valve unit. When the first pilot valve unit is in an open state and the second pilot valve unit is in a closed state, the first pilot chamber communicates with the low-pressure refrigerant outlet port and contracts, moving the valve element to the first position. When the first pilot valve unit is in a closed state and the second pilot valve unit is in an open state, the second pilot chamber communicates with the low-pressure refrigerant outlet port and contracts, moving the valve element to the second position. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the four-way selector valve when it is in a first state. [Figure 3] 4 is a cross-sectional view of a four-way switching valve in the middle of switching from a first state to a second state. FIG. [Figure 4] FIG. 4 is a cross-sectional view of the four-way selector valve in a second state. [Figure 5] FIG. [Figure 6] 10 is a flowchart of a stop position control of the valve body. [Figure 7] 10 is a flowchart of thermo-off control. DETAILED DESCRIPTION OF THE INVENTION

[0024] (1) Configuration of the Air Conditioner 100 Fig. 1 is a configuration diagram of an air conditioner 100 according to one embodiment of the present invention. In Fig. 1, the air conditioner 100 is a refrigeration device capable of cooling and heating operations, and includes an indoor unit 20, an outdoor unit 10, and a liquid refrigerant communication pipe 31 and a gas refrigerant communication pipe 32 for connecting the outdoor unit 10 and the indoor unit 20. The refrigerant circuit 30 of the air conditioner 100 is filled with CO2 as a refrigerant. However, the refrigerant is not limited to CO2, and other refrigerants, such as R32, may also be used.

[0025] (1-1) Indoor unit 20 The indoor unit 20 has an indoor heat exchanger 23 and an indoor fan 24. The indoor unit 20 is also equipped with a remote control unit 93. The remote control unit 93 communicates with the control unit 90 built into the indoor unit 20 and the outdoor unit 10 to control the air conditioner 100 in response to user operations.

[0026] (1-1-1) Indoor heat exchanger 23 The indoor heat exchanger 23 is a cross-fin type fin-and-tube heat exchanger consisting of a heat transfer tube and multiple fins. The indoor heat exchanger 23 functions as a refrigerant evaporator to cool the indoor air during cooling operation, and as a refrigerant condenser to heat the indoor air during heating operation.

[0027] The indoor heat exchanger 23 is not limited to a cross-fin type fin-and-tube heat exchanger, and may be a heat exchanger of another type.

[0028] (1-1-2) Indoor fan 24 The indoor fan 24 is a cross-flow fan. The indoor fan 24 is driven by an indoor fan motor 24a. However, the indoor fan 24 is not limited to a cross-flow fan, and may be, for example, a turbo fan.

[0029] When the indoor fan 24 is operated, the indoor unit 20 draws indoor air into the interior, exchanges heat with the refrigerant in the indoor heat exchanger 23, and then supplies the air to the room. The indoor fan 24 can also change the air volume of the air supplied to the indoor heat exchanger 23 within a predetermined air volume range.

[0030] (1-2) Outdoor unit 10 1, the outdoor unit 10 has a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, and an expansion valve 15. The outdoor unit 10 also has an outdoor fan 14.

[0031] (1-2-1) Compressor 11 The compressor 11 is a variable displacement compressor, and its rotation speed is controlled by an inverter. In this embodiment, there is only one compressor 11, but this is not limited to this, and two or more compressors may be connected in parallel depending on the number of indoor units 20 connected, etc.

[0032] (1-2-2) Four-way switching valve 12 The four-way switching valve 12 is a valve that switches the direction of refrigerant flow. During cooling operation, the four-way switching valve 12 connects the discharge side of the compressor 11 to the gas side of the outdoor heat exchanger 13, and also connects the suction side of the compressor 11 to the gas refrigerant connection pipe 32. This is the state shown by the solid lines of the four-way switching valve 12 in Figure 1, and is called the first state. As a result, the outdoor heat exchanger 13 functions as a refrigerant condenser, and the indoor heat exchanger 23 functions as a refrigerant evaporator.

[0033] During heating operation, the four-way selector valve 12 connects the discharge side of the compressor 11 to the gas refrigerant connection pipe 32, and also connects the suction side of the compressor 11 to the gas side of the outdoor heat exchanger 13. This is the state shown by the dashed lines of the four-way selector valve 12 in Figure 1, and is called the second state. As a result, the indoor heat exchanger 23 functions as a refrigerant condenser, and the outdoor heat exchanger 13 functions as a refrigerant evaporator.

[0034] (1-2-3) Outdoor heat exchanger 13 The outdoor heat exchanger 13 is a cross-fin type fin-and-tube heat exchanger. The outdoor heat exchanger 13 functions as a refrigerant condenser during cooling operation and as a refrigerant evaporator during heating operation. The gas side of the outdoor heat exchanger 13 is connected to the four-way switching valve 12, and the liquid side is connected to the expansion valve 15.

[0035] The outdoor heat exchanger 13 is not limited to a cross-fin type fin-and-tube heat exchanger, and may be a heat exchanger of another type.

[0036] (1-2-4) Expansion valve 15 The expansion valve 15 adjusts the pressure, flow rate, etc. of the refrigerant flowing in the refrigerant circuit 30. The expansion valve 15 is disposed downstream of the outdoor heat exchanger 13 in the direction of refrigerant flow in the refrigerant circuit 30 during cooling operation.

[0037] (1-2-5) Outdoor fan 14 The outdoor fan 14 blows the drawn outdoor air into the outdoor heat exchanger 13 to exchange heat with the refrigerant. The outdoor fan 14 can vary the air volume when blowing air to the outdoor heat exchanger 13. The outdoor fan 14 is driven by an outdoor fan motor 14a.

[0038] (1-3) Control unit 90 The control unit 90 controls the operating frequency of the compressor 11 , the switching operation of the four-way switching valve 12 , and the opening degree of the expansion valve 15 based on a command signal from a remote control unit 93 .

[0039] 1, the control unit 90 has an indoor control unit 92 built into the indoor unit 20 and an outdoor control unit 91 built into the outdoor unit 10. Infrared signals are transmitted and received between the indoor control unit 92 and the remote control unit 93. Signals are transmitted and received between the indoor control unit 92 and the outdoor control unit 91 via a wire.

[0040] (2) Operation of the Air Conditioner 100 In the air conditioner 100, the four-way switching valve 12 can switch the refrigerant circulation cycle to either a circulation cycle during cooling operation or a circulation cycle during heating operation.

[0041] (2-1) Cooling operation In cooling operation, the four-way switching valve 12 is set to the first state (the state indicated by the solid line of the four-way switching valve 12 in FIG. 1). When the control unit 90 operates the compressor 11 in this state, a vapor compression refrigeration cycle is performed in which the outdoor heat exchanger 13 serves as a condenser and the indoor heat exchanger 23 serves as an evaporator.

[0042] The high-pressure refrigerant discharged from the compressor 11 exchanges heat with outdoor air in the outdoor heat exchanger 13 and condenses. The refrigerant that has left the outdoor heat exchanger 13 is reduced in pressure when passing through the expansion valve 15, and then exchanges heat with indoor air in the indoor heat exchanger 23 and evaporates. During this process, the air is cooled by the indoor heat exchanger 23, and the cooled air is blown into the room from the indoor unit 20 via the indoor fan 24. The refrigerant that has left the indoor heat exchanger 23 is drawn into the compressor 11 and compressed.

[0043] (2-2) Heating operation In heating operation, the four-way switching valve 12 is set to the second state (the state indicated by the dotted line of the four-way switching valve 12 in FIG. 1). When the control unit 90 operates the compressor 11 in this state, a vapor compression refrigeration cycle is performed in which the outdoor heat exchanger 13 serves as an evaporator and the indoor heat exchanger 23 serves as a condenser.

[0044] The high-pressure refrigerant discharged from the compressor 11 exchanges heat with indoor air in the indoor heat exchanger 23 and condenses. At that time, the air is heated in the indoor heat exchanger 23, and the heated air is blown out into the room from the indoor unit 20 via the indoor fan 24. The condensed refrigerant is reduced in pressure when passing through the expansion valve 15, and then evaporates by exchanging heat with outdoor air in the outdoor heat exchanger 13. The refrigerant that leaves the outdoor heat exchanger 13 is drawn into the compressor 11 and compressed.

[0045] (3) Configuration of four-way switching valve 12 Fig. 2 is a cross-sectional view of four-way switching valve 12 in Fig. 1 in a first state indicated by solid lines. Fig. 3 is a cross-sectional view of four-way switching valve 12 in Fig. 1 in the middle of switching from the first state indicated by solid lines to a second state indicated by dotted lines. Fig. 4 is a cross-sectional view of four-way switching valve 12 in Fig. 1 in the second state indicated by dotted lines. In Figs. 2, 3, and 4, four-way switching valve 12 includes flow path switching valve section 50, pilot valve section 60, and capillary tubes 81a to 81c connecting flow path switching valve section 50 and pilot valve section 60.

[0046] (3-1) Flow path switching valve unit 50 The flow path switching valve unit 50 includes a cylinder 51, a valve element 52, a first piston 53a, a second piston 53b, a piston rod 54, a first pilot chamber 55a, and a second pilot chamber 55b.

[0047] (3-1-1) Cylinder 51 Cylinder 51 is a metallic cylindrical member whose ends are closed by first plug 511 and second plug 512. When viewed from the front in Figures 2, 3, and 4, first plug 511 closes the left end of cylinder 51, and second plug 512 closes the right end of cylinder 51. First plug 511 has a through-hole 511a. Second plug 512 has a through-hole 512a.

[0048] The side wall of the cylinder 51 is provided with a first flow path Pa, a second flow path Pb, a third flow path Pc, and a fourth flow path Pd that connect the inside of the cylinder 51 with the refrigerant circuit 30.

[0049] The first flow path Pa is provided in the center of the side wall of the cylinder 51 and is connected to the discharge pipe of the compressor 11. The second flow path Pb is provided at a position opposite to the first flow path Pa and is connected to the suction pipe of the compressor 11.

[0050] The third flow path Pc and the fourth flow path Pd are arranged side by side with the second flow path Pb interposed therebetween in the axial direction of the cylinder 51. The third flow path Pc is connected to the outdoor heat exchanger 13, and the fourth flow path Pd is connected to the indoor heat exchanger 23.

[0051] The interior of the cylinder 51 is a cavity 510 that communicates with the first flow path Pa, the second flow path Pb, the third flow path Pc, and the fourth flow path Pd. The open ends of the second flow path Pb, the third flow path Pc, and the fourth flow path Pd on the cavity 510 side form valve seats 56 with flat sliding surfaces.

[0052] (3-1-2) Valve body 52 The valve element 52 slides in contact with the sliding surface of the valve seat 56. The valve element 52 has a length in the sliding direction that covers two adjacent openings among the openings of the second flow path Pb, the third flow path Pc, and the fourth flow path Pd. The valve element 52 also has a recess 52a on the side facing the sliding surface of the valve seat 56 that connects the two openings that it covers.

[0053] (3-1-2-1) First position of the valve body 52 2, the valve element 52 is in a position where the openings of the second flow path Pb and the fourth flow path Pd communicate with each other, and this position is referred to as the first position. When the valve element 52 is in the first position, the refrigeration cycle operates in cooling mode, and high-pressure gas refrigerant discharged from the compressor 11 flows from the first flow path Pa into the cylinder 51, flows from the third flow path Pc to the outdoor heat exchanger 13, where it condenses, is decompressed by the expansion valve 15, evaporates in the indoor heat exchanger 23, and is drawn into the compressor 11 through the fourth flow path Pd and the second flow path Pb.

[0054] (3-1-2-2) Second position of the valve body 52 4, the valve element 52 is in a position where the openings of the second flow path Pb and the third flow path Pc communicate with each other, and this position is referred to as the second position. When the valve element 52 is in the second position, the refrigeration cycle operates in heating mode, and high-pressure gas refrigerant discharged from the compressor 11 flows from the first flow path Pa into the cylinder 51, flows from the fourth flow path Pd to the indoor heat exchanger 23 where it condenses, is decompressed by the expansion valve 15, evaporates in the outdoor heat exchanger 13, and is drawn into the compressor 11 through the third flow path Pc and the second flow path Pb.

[0055] (3-1-2-3) Third position of the valve body 52 In Figure 3, the valve element 52 is located between the first position and the second position. This position is called the third position. The third position is a position to which the valve element 52, which is located in the first position or the second position, gradually moves.

[0056] Alternatively, when the operation is switched and the power is turned off while the valve body 52 is moving from the first position to the second position or from the second position to the first position, the valve body 52 stops at this position without reaching either the first position or the second position.

[0057] (3-1-3) First piston 53a, second piston 53b, and piston rod 54 In the cavity 510 of the cylinder 51, a first piston 53a and a second piston 53b connected by a piston rod 54 are slidably disposed.

[0058] 2, 3, and 4, the first piston 53a is located between the first plug 511 and the fourth flow path Pd. The first piston 53a has a small hole 531 that penetrates in the axial direction.

[0059] 2, 3, and 4, the second piston 53b is located between the second plug 512 and the third flow path Pc. The second piston 53b has a small hole 532 that penetrates in the axial direction.

[0060] The piston rod 54 holds the valve body 52 and moves together with the first piston 53a and the second piston 53b.

[0061] (3-1-4) First pilot chamber 55a and second pilot chamber 55b First pilot chamber 55a is a space sandwiched between first plug 511 and first piston 53a. Second pilot chamber 55b is a space sandwiched between second plug 512 and second piston 53b.

[0062] A portion of the high-pressure refrigerant flowing in from the first flow path Pa flows through the small hole 531 of the first piston 53a into the first pilot chamber 55a, and also flows through the small hole 532 of the second piston 53b into the second pilot chamber 55b.

[0063] When there is a difference in pressure between the first pilot chamber 55a and the second pilot chamber 55b, the first piston 53a, the second piston 53b, the piston rod 54, and the valve body 52 move.

[0064] For example, in Figure 2, the pressure in the first pilot chamber 55a is smaller than the pressure in the second pilot chamber 55b, so the first piston 53a, the second piston 53b, the piston rod 54, and the valve body 52 move to the left when viewed from the front in Figure 2, and the position of the valve body 52 at that time is the first position.

[0065] Also, in Figure 4, since the pressure in the first pilot chamber 55a is greater than the pressure in the second pilot chamber 55b, the first piston 53a, the second piston 53b, the piston rod 54 and the valve body 52 move to the right when viewed from the front in Figure 4, and the position of the valve body 52 at that time is the second position.

[0066] (3-2) Pilot valve section 60 The pilot valve portion 60 has a first pilot valve portion 60a and a second pilot valve portion 60b.

[0067] (3-2-1) First pilot valve portion 60a The first pilot valve portion 60a has a valve body 61, a first valve seat 61a, a first valve chamber 62a, a first plunger 63a, a first solenoid 64a, and a first coil spring 65a.

[0068] The valve body 61 also serves as the second pilot valve portion 60b. The first valve seat 61a is formed inside the valve body 61. The first valve chamber 62a is a space in which the first plunger 63a moves, and communicates with an opening in the first valve seat 61a.

[0069] The first plunger 63a moves within the first valve chamber 62a to open and close the opening of the first valve seat 61a. When the first solenoid 64a is energized, it generates an electromagnetic force to move the first plunger 63a in a direction away from the opening of the first valve seat 61a. The first coil spring 65a constantly pushes the first plunger 63a in a direction to close the opening of the first valve seat 61a.

[0070] The electromagnetic force of the first solenoid 64a is greater than the force with which the first coil spring 65a presses the first plunger 63a, so when the first solenoid 64a is energized, the opening of the first valve seat 61a opens.When the first solenoid 64a is not energized, the first coil spring 65a presses the first plunger 63a to close the opening of the first valve seat 61a.

[0071] (3-2-2) Second pilot valve portion 60b The second pilot valve portion 60b has a valve body 61, a second valve seat 61b, a second valve chamber 62b, a second plunger 63b, a second solenoid 64b, and a second coil spring 65b.

[0072] The valve body 61 also serves as the first pilot valve portion 60a. The second valve seat 61b is formed inside the valve body 61. The second valve chamber 62b is a space in which the second plunger 63b moves, and communicates with an opening in the second valve seat 61b.

[0073] The second plunger 63b moves within the second valve chamber 62b to open and close the opening of the second valve seat 61b. When the second solenoid 64b is energized, it generates an electromagnetic force to move the second plunger 63b in a direction away from the opening of the second valve seat 61b. The second coil spring 65b constantly pushes the second plunger 63b in a direction to close the opening of the second valve seat 61b.

[0074] The electromagnetic force of the second solenoid 64b is greater than the force with which the second coil spring 65b pushes the second plunger 63b, so when the second solenoid 64b is energized, the opening of the second valve seat 61b opens.When the second solenoid 64b is not energized, the second coil spring 65b pushes the second plunger 63b to close the opening of the second valve seat 61b.

[0075] (3-2-3) Configuration of the valve body 61 Fig. 5 is an enlarged cross-sectional view of the valve body 61. In Fig. 5, an opening of a first valve seat 61a and an opening of a second valve seat 61b formed in the valve body 61 communicate with each other via a first communication hole 611. The valve body 61 also has a second communication hole 612, a third communication hole 613, and a fourth communication hole 614.

[0076] The second communication hole 612 communicates with the first communication hole 611. Furthermore, the second communication hole 612 is connected to the second flow path Pb of the flow path switching valve unit 50 via a capillary tube 81c, as shown in FIGS.

[0077] The third communication hole 613 communicates with the first valve chamber 62a. In addition, the third communication hole 613 is connected to the first pilot chamber 55a of the flow path switching valve unit 50 via a capillary tube 81a, as shown in Figures 2, 3, and 4.

[0078] The fourth communication hole 614 communicates with the second valve chamber 62b. In addition, the fourth communication hole 614 is connected to the second pilot chamber 55b of the flow path switching valve unit 50 via a capillary tube 81b, as shown in Figures 2, 3, and 4.

[0079] (4) Operation of the four-way switching valve 12 The four-way switching valve 12 switches the position of the valve element 52 of the flow path switching valve section 50 between the first position and the second position by switching between opening and closing the first pilot valve section 60a and the second pilot valve section 60b.

[0080] The following explanation will be based on the assumption that when the first pilot valve section 60a is energized and in an open state, the second pilot valve section 60b is de-energized and in a closed state, and when the first pilot valve section 60a is de-energized and in a closed state, the second pilot valve section 60b is energized and in an open state.

[0081] (4-1) When the first pilot valve portion 60a is open and the second pilot valve portion is closed 2 and 5, when the first solenoid 64a is energized, the electromagnetic force of the first solenoid 64a moves the first plunger 63a away from the opening of the first valve seat 61a against the spring force of the first coil spring 65a. As a result, the opening of the first valve seat 61a opens, the first valve chamber 62a communicates with the third communication hole 613, the refrigerant flows from the first pilot chamber 55a of the flow path switching valve unit 50 to the second flow path Pb via the capillary tubes 81a and 81c, and the pressure in the first pilot chamber 55a changes to low.

[0082] On the other hand, because the second solenoid 64b is not energized, the second plunger 63b is pushed by the second coil spring 65b in a direction to close the second valve seat 61b. Therefore, the second plunger 63b blocks communication between the second valve chamber 62b and the fourth communication hole 614, so that refrigerant does not flow from the second pilot chamber 55b of the flow path switching valve unit 50 to the second flow path Pb, and the second pilot chamber 55b maintains a high pressure.

[0083] As a result, the first piston 53a, the second piston 53b, the piston rod 54, and the valve body 52 move in a direction that reduces the space of the first pilot chamber 55a, and the valve body 52 reaches the first position. At this time, the first flow path Pa and the third flow path Pc communicate with each other, and the high-pressure gas refrigerant from the compressor 11 flows to the outdoor heat exchanger 13, and the second flow path Pb and the fourth flow path Pd communicate with each other, and the low-pressure refrigerant from the indoor heat exchanger 23 is drawn into the compressor 11.

[0084] (4-2) When the first pilot valve portion 60a is closed and the second pilot valve portion is open 4 and 5, when the second solenoid 64b is energized, the electromagnetic force of the second solenoid 64b moves the second plunger 63b away from the opening of the second valve seat 61b against the spring force of the second coil spring 65b. As a result, the opening of the second valve seat 61b opens, the second valve chamber 62b communicates with the fourth communication hole 614, the refrigerant flows from the second pilot chamber 55b of the flow path switching valve unit 50 to the second flow path Pb via the capillary tubes 81b and 81c, and the pressure in the second pilot chamber 55b changes to low.

[0085] On the other hand, because the first solenoid 64a is not energized, the first plunger 63a is pushed by the first coil spring 65a in a direction to close the first valve seat 61a. Therefore, the first plunger 63a blocks communication between the first valve chamber 62a and the third communication hole 613, so that refrigerant does not flow from the first pilot chamber 55a of the flow path switching valve unit 50 to the second flow path Pb, and the first pilot chamber 55a maintains a high pressure.

[0086] As a result, the first piston 53a, the second piston 53b, the piston rod 54, and the valve body 52 move in a direction that reduces the space of the second pilot chamber 55b, and the valve body 52 reaches the second position. At this time, the first flow path Pa and the fourth flow path Pd communicate with each other, and the high-pressure gas refrigerant from the compressor 11 flows to the indoor heat exchanger 23, and the second flow path Pb and the third flow path Pc communicate with each other, and the low-pressure refrigerant from the outdoor heat exchanger 13 is drawn into the compressor 11.

[0087] (5) Stop position control of the valve element 52 in the four-way switching valve 12 When the refrigerant circuit 30 is filled with CO2, a slightly flammable refrigerant, or a flammable refrigerant, safety measures are necessary to prevent leakage into the room. In this embodiment, when the air conditioner 100 stops during heating operation with the high-pressure refrigerant facing the indoor side, the valve element 52 is moved to the first position to reduce the pressure in order to reduce the risk of refrigerant leakage into the room.

[0088] 6 is a flowchart of the stop position control of the valve element 52. The stop position control of the valve element 52 will be described below with reference to the drawings.

[0089] (Step S1) In step S1, the control unit 90 determines whether or not there is a command to stop operation of the air conditioner 100, and if there is a command to stop operation, the process proceeds to step S2.

[0090] (Step S2) In step S2, the control unit 90 stops the air conditioner 100, and proceeds to step S3.

[0091] (Step S3) In step S3, the control unit 90 determines whether the air conditioner 100 has stopped in heating operation. If the control unit 90 determines that the air conditioner 100 has stopped in heating operation, the control unit 90 proceeds to step S4. If the control unit 90 determines that the air conditioner 100 has not stopped in heating operation, the control unit 90 proceeds to step S5.

[0092] (Step S4) In step S4, the control unit 90 moves the valve element 52 of the four-way switching valve 12 to the first position. When the air conditioner 100 is stopped in heating operation, the valve element 52 of the four-way switching valve 12 is in the second position. Therefore, if the position of the valve element 52 is moved from the second position to the first position, the refrigerant pressure in the indoor heat exchanger 23 decreases after operation is stopped, even if it was high immediately before operation was stopped. As a result, the refrigerant pressure in the indoor heat exchanger 23 is not maintained at a high pressure while operation is stopped, and behavior that promotes refrigerant leakage is suppressed.

[0093] Here, "immediately before stopping operation" means immediately before receiving a command to stop operation. Also, "stopping operation" means a state in which at least the compressor 11 has stopped.

[0094] Furthermore, the process of “moving the valve element 52 to the first position” in step S4 specifically means “opening the first pilot valve portion 60a and closing the second pilot valve portion 60b,” thereby moving the valve element 52 to the first position.

[0095] Furthermore, the process of "opening the first pilot valve portion 60a and closing the second pilot valve portion 60b" specifically means "energizing the first pilot valve portion 60a and not energizing the second pilot valve portion 60b." In this case, the first solenoid 64a is energized, the first plunger 63a is moved away from the first valve seat 61a by electromagnetic force, and the first pilot chamber 55a of the flow path switching valve portion 50 communicates with the second flow path Pb. As a result, the first pilot chamber 55a contracts, and the valve element 52 moves to the first position.

[0096] On the other hand, no electromagnetic force is generated in the second solenoid 64b, and the second valve seat 61b is closed by the second plunger 63b.

[0097] After the process of "energizing the first pilot valve portion 60a and not energizing the second pilot valve portion 60b" is performed, it is desirable to stop energizing the first pilot valve portion 60a and the second pilot valve portion 60b. This is because even if the energization is stopped, the position of the valve element 52 is maintained in the first position, thereby suppressing unnecessary power consumption.

[0098] (Step S5) In step S5, the control unit 90 maintains the valve element 52 of the four-way switching valve 12 in the first position. If the air conditioner 100 has stopped during an operation other than heating operation, it is considered that the air conditioner 100 has stopped during cooling operation or defrosting operation, which has the same refrigerant circulation cycle as cooling operation, and therefore the valve element 52 of the four-way switching valve 12 is in the first position. Therefore, it is sufficient to maintain the position of the valve element 52 in the first position.

[0099] Furthermore, the process of “maintaining the position of the valve element 52 at the first position” in step S5 specifically means “opening the first pilot valve portion 60a and closing the second pilot valve portion 60b, or closing both the first pilot valve portion 60a and the second pilot valve portion 60b.” This determines and maintains the valve element 52 at the first position.

[0100] Furthermore, the process of "opening the first pilot valve section 60a and closing the second pilot valve section 60b, or closing both the first pilot valve section 60a and the second pilot valve section 60b" specifically means "energizing the first pilot valve section 60a and not energizing the second pilot valve section 60b, or not energizing the first pilot valve section 60a and the second pilot valve section 60b." For ease of explanation, the former processes are referred to as Process A and Process B.

[0101] As in process A, when the first pilot valve portion 60a is energized but the second pilot valve portion 60b is not, the first solenoid 64a is energized, the first plunger 63a is moved away from the first valve seat 61a by electromagnetic force, and the first pilot chamber 55a of the flow path switching valve portion 50 communicates with the second flow path Pb. As a result, the first pilot chamber 55a contracts and the valve element 52 moves to the first position. On the other hand, no electromagnetic force is generated in the second solenoid 64b, and the second valve seat 61b is closed by the second plunger 63b.

[0102] The advantage of process A is that, for example, if operation is stopped at the time of switching from defrost operation to heating operation and valve body 52 stops between the first position and the second position, valve body 52 can be reliably moved to the first position.

[0103] On the other hand, when the first pilot valve portion 60a and the second pilot valve portion 60b are not energized as in process B, no electromagnetic force is generated in the first solenoid 64a and the second solenoid 64b, the first valve seat 61a is closed by the first plunger 63a, and the second valve seat 61b is closed by the second plunger 63b. As a result, the pressure difference between the first pilot chamber 55a and the second pilot chamber 55b of the flow path switching valve portion 50 is maintained, and the position of the valve element 52 is also maintained at the first position.

[0104] Since energizing the first pilot valve section 60a to maintain the open state after operation has stopped would result in unnecessary consumption of electricity, process B, in which no electricity is applied to the first pilot valve section 60a after operation has stopped, is rational.

[0105] Therefore, it is desirable to set the valve element 52 to the first position by process A, and then maintain the valve element 52 at the first position by process B.

[0106] As a supplementary note regarding the stop position control of the valve element 52, step S2 in FIG. 6 may be executed after the processing of steps S4 and S5.

[0107] In this case, step S3 does not determine whether the operation has been stopped during heating operation, but determines whether the operation when the operation stop command was received in step S1 was heating operation.

[0108] (6) Variations In the above embodiment, the first pilot valve portion 60a is open when energized and closed when de-energized, and the second pilot valve portion 60b is also open when energized and closed when de-energized. However, this is not limited to this, and the first pilot valve portion 60a may be closed when energized and open when de-energized, and the second pilot valve portion 60b may also be closed when energized and open when de-energized.

[0109] (7) Features (7-1) In the air conditioner 100, by maintaining the position of the valve body in the first position after operation is stopped or moving it to the first position, even if the refrigerant pressure in the indoor heat exchanger is high immediately before operation is stopped, it decreases immediately after operation is stopped. Therefore, the refrigerant pressure in the indoor heat exchanger is not maintained at high pressure while operation is stopped, and behavior that promotes refrigerant leakage is suppressed.

[0110] (7-2) In the air conditioner 100, when the valve element 52 is in the first position, the first pilot valve section 60a is open and the second pilot valve section 60b is closed, or both the first pilot valve section 60a and the second pilot valve section 60b are closed. The position of the valve element 52 is maintained or the valve element 52 is moved by a combination of opening and closing the first pilot valve section 60a and the second pilot valve section 60b, making control easy.

[0111] (7-3) In the air conditioner 100, the first pilot valve portion 60a and the second pilot valve portion 60b can be switched between open and closed states by energizing or de-energizing them, so the valve bodies can be operated more quickly than with motor-driven valves.

[0112] (7-4) In the air conditioner 100, closing the first pilot valve section 60a and the second pilot valve section 60b after the valve body 52 has moved means putting the first pilot valve section 60a and the second pilot valve section 60b into a non-energized state, thereby reducing power consumption.

[0113] (7-5) In the air conditioner 100, when a command to stop the refrigeration cycle operation is received and the operation is heating operation and the valve element 52 is in the second position or a third position between the first and second positions, the control unit 90 moves the valve element 52 to the first position. As a result, even if the refrigerant pressure in the second heat exchanger is high immediately before the operation is stopped, it decreases immediately after the operation is stopped. Therefore, the refrigerant pressure in the second heat exchanger is not maintained at a high pressure during the operation stop, and an operation that promotes refrigerant leakage is suppressed.

[0114] (7-6) In the air conditioner 100, when the control unit 90 sets the position of the valve element 52 to the first position, it opens the first pilot valve unit 60a and closes the second pilot valve unit 60b. The movement of the valve element 52 is achieved by a combination of opening and closing the first pilot valve unit 60a and the second pilot valve unit 60b, making control easy.

[0115] (7-7) In the air conditioner 100, if the position of the valve element 52 is the first position and the first pilot valve unit 60a is in the open state when a command to stop the refrigeration cycle operation is received, the control unit 90 closes the first pilot valve unit 60a. Closing the first pilot valve unit 60a means de-energizing the first pilot valve unit 60a, and the first pilot valve unit 60a and the second pilot valve unit 60b are de-energized, thereby reducing power consumption.

[0116] (7-8) When the first pilot valve portion 60a is in the open state and the second pilot valve portion 60b is in the closed state, the first pilot chamber 55a of the four-way switching valve 12 communicates with the second flow path Pb and contracts, moving the valve element 52 to the first position. When the first pilot valve portion 60a is in the closed state and the second pilot valve portion 60b is in the open state, the second pilot chamber 55b of the four-way switching valve 12 communicates with the second flow path Pb and contracts, moving the valve element 52 to the second position.

[0117] (8) Other embodiments When the air conditioner 100 is a paired unit in which one outdoor unit 10 is connected to one indoor unit 20, the stop position control of the valve element 52 is not limited to when operation is stopped due to the power being turned off. For example, the stop position control of the valve element 52 is also performed when the difference between the indoor set temperature and the indoor temperature falls within a predetermined range, stopping the compressor and causing a so-called thermo-off state.

[0118] 7 is a flowchart of thermo-off control. Here, as an example, stop position control of the valve element 52 according to another embodiment will be described with reference to FIG.

[0119] (Step S11) In step S11, the control unit 90 acquires an indoor set temperature Ts as the set temperature of the room, which is the space to be air-conditioned. The indoor set temperature Ts is set by the user via the remote control unit 93.

[0120] (Step S12) In step S12, the control unit 90 detects the room temperature Tr via the room temperature sensor 95. The room temperature sensor 95 is disposed in the indoor unit 20.

[0121] (Step S13) In step S13, the control unit 90 determines whether the absolute value of the difference between the indoor set temperature Ts and the indoor temperature Tr is equal to or less than a predetermined value X. If the control unit 90 determines that the absolute value of the difference between the indoor set temperature Ts and the indoor temperature Tr is equal to or less than the predetermined value X, the process proceeds to step S14. On the other hand, if the control unit 90 determines that the absolute value of the difference between the indoor set temperature Ts and the indoor temperature Tr is not equal to or less than the predetermined value X, the process returns to step S11.

[0122] (Step S14) In step S14, the control unit 90 stops the compressor 11, and the process proceeds to step S3 shown in FIG.

[0123] (Step S3) In step S3, the control unit 90 determines whether the air conditioner 100 has stopped in heating operation. If the control unit 90 determines that the air conditioner 100 has stopped in heating operation, the control unit 90 proceeds to step S4. If the control unit 90 determines that the air conditioner 100 has not stopped in heating operation, the control unit 90 proceeds to step S5.

[0124] (Step S4) In step S4, the control unit 90 moves the valve element 52 of the four-way switching valve 12 to the first position. To move the valve element 52 to the first position, specifically, the first pilot valve element 60a is opened and the second pilot valve element 60b is closed. This moves the valve element 52 to the first position.

[0125] (Step S5) In step S5, the control unit 90 maintains the valve element 52 of the four-way switching valve 12 in the first position. To maintain the valve element 52 in the first position, specifically, the first pilot valve portion 60a is opened and the second pilot valve portion 60b is closed, or both the first pilot valve portion 60a and the second pilot valve portion 60b are closed. This determines and maintains the valve element 52 in the first position.

[0126] If the valve element 52 is kept in the first position after the heating operation is stopped, the refrigerant pressure in the indoor heat exchanger 23 decreases immediately after the operation is stopped, even if it was high immediately before the operation was stopped. As a result, the refrigerant pressure in the indoor heat exchanger 23 is not maintained at a high pressure while the operation is stopped, and an operation that promotes refrigerant leakage is suppressed.

[0127] In addition, when the compressor 11 is stopped, the valve body 52 is maintained in the first position or moved to the first position to reduce the refrigerant pressure in the indoor heat exchanger 23, thereby suppressing hunting, which is a phenomenon in which the indoor heat exchanger 23 quickly becomes high pressure and the compressor 11 repeatedly starts and stops.

[0128] In addition, the control unit 90 may store the number of times the compressor 11 is started and stopped per predetermined time during heating operation, and may control the valve body 52 to move to the first position if the number of times the compressor 11 is started and stopped per predetermined time immediately before thermo-off is equal to or greater than the predetermined number.

[0129] Furthermore, when the air conditioning load is greater than a predetermined load, it is unlikely that the compressor 11 will repeatedly start and stop, so the valve element 52 may be controlled to be maintained in the second position during heating operation.

[0130] 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]

[0131] 11 Compressor 12 Four-way switching valve 13 Outdoor heat exchanger (1st heat exchanger) 15 Expansion valve 23 Indoor heat exchanger (second heat exchanger) 30 Refrigerant circuit 50 Flow path switching valve 52 Valve body 55a First Pilot Room 55b Second Pilot Room 60 Pilot valve section 60a First pilot valve section 60b Second pilot valve section 90 Control Unit 100 Air conditioners (refrigeration units) Pa First flow path (high-pressure refrigerant inlet) Pb Second flow path (low pressure refrigerant inlet) Pc Third flow path Pd 4th flow path [Prior art documents] [Patent documents]

[0132] [Patent Document 1] Japanese Patent Application Publication No. 11-294607

Claims

1. A refrigeration system in which a refrigerant circulates through a refrigerant circuit (30) including a compressor (11), a four-way switching valve (12), a first heat exchanger (13), an expansion valve (15), and a second heat exchanger (23), and a refrigeration cycle operation is performed, The four-way switching valve (12) is a flow path switching valve unit (50) having a valve element (52) movable between a first position and a second position different from the first position; a pilot valve portion (60) that moves the valve body (52); Equipped with The pilot valve portion (60) a first pilot valve portion (60a); a second pilot valve portion (60b); and The refrigeration cycle operation is When the valve body (52) is in the first position, a cooling operation is performed in which the refrigerant discharged from the compressor (11) is sent to the first heat exchanger (13) via the four-way switching valve (12), When the valve body (52) is in the second position, a heating operation is performed in which the refrigerant discharged from the compressor (11) is sent to the second heat exchanger (23) via the four-way switching valve (12), When the refrigeration cycle operation is stopped, the valve body (52) is maintained at the first position or moved to the first position after the operation is stopped. A refrigeration device (100).

2. When the valve body (52) is in the first position, the first pilot valve portion (60a) is in an open state and the second pilot valve portion (60b) is in a closed state, or Both the first pilot valve portion (60a) and the second pilot valve portion (60b) are in a closed state. The refrigeration system (100) of claim 1.

3. Each of the first pilot valve portion (60a) and the second pilot valve portion (60b) is an electromagnetic on-off valve, and the on-off state of the on-off valve is switched by switching the energized state. Refrigeration system (100) according to claim 1 or claim 2.

4. The system further includes a control unit (90) that controls the four-way switching valve (12), The first pilot valve portion (60a) and the second pilot valve portion (60b) are each in a closed state when not energized and in an open state when energized, When a command to stop the refrigeration cycle operation is received, the control unit (90) maintains the position of the valve element (52) at the first position, moves the valve element (52) to the first position, and then closes the first pilot valve unit (60a) and the second pilot valve unit (60b).

4. The refrigeration system (100) of claim 3.

5. When a command to stop the refrigeration cycle operation is received, if the valve element (52) is in the second position or a third position between the first position and the second position, the control unit (90) moves the valve element (52) to the first position. Refrigeration system (100) according to claim 4.

6. When the control unit (90) sets the position of the valve body (52) to the first position, the control unit (90) sets the first pilot valve unit (60a) to an open state and the second pilot valve unit (60b) to a closed state. Refrigeration device (100) according to claim 4 or claim 5.

7. the control unit (90) closes the first pilot valve unit (60a) when the position of the valve element (52) is the first position and the first pilot valve unit (60a) is in an open state when a command to stop the refrigeration cycle operation is received. Refrigeration system (100) according to claim 4.

8. When the difference between the temperature of the air-conditioned space and the set temperature falls within a predetermined range and the control unit (90) stops the compressor (11), the control unit (90) maintains the valve body (52) at the first position or moves the valve body (52) to the first position. Refrigeration system (100) according to claim 4.

9. The flow path switching valve unit (50) a high-pressure refrigerant inlet (Pa) for introducing a high-pressure refrigerant from the high-pressure side of the compressor (11); a low-pressure refrigerant outlet (Pb) that guides the incoming low-pressure refrigerant to the low-pressure side of the compressor (11); a first pilot chamber (55a) communicating with the first pilot valve portion (60a); a second pilot chamber (55b) communicating with the second pilot valve portion (60b); and the first pilot chamber (55a) communicates with the low-pressure refrigerant outflow portion (Pb) and contracts when the first pilot valve portion (60a) is in an open state and the second pilot valve portion (60a) is in a closed state, thereby moving the valve body (52) to the first position; When the first pilot valve portion (60a) is in a closed state and the second pilot valve portion (60b) is in an open state, the second pilot chamber (55b) communicates with the low-pressure refrigerant outflow portion (Pb) and contracts to move the valve body (52) to the second position. The refrigeration system (100) of claim 2.

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