RU2774135C1 - Refrigeration cycle device - Google Patents

Abstract

FIELD: refrigeration engineering.

SUBSTANCE: invention relates to refrigeration engineering. The device for implementing the refrigeration cycle includes the first flow switching valve, including the first-fourth holes, the second flow switching valve and the third flow switching valve, including the fifth-seventh holes, the compressor, the outlet of which is connected to the first hole, the first high-pressure pipe, providing connection between the outlet pipe and the fifth holes, a bypass expansion valve located in the section of the first high pressure pipe, a first outdoor heat exchanger connected to the seventh port of the second flow switch valve, a second outdoor heat exchanger connected to the seventh port of the third flow switch valve, and a controller. The controller is configured to perform a differential pressure guarantee process upon switching of the second flow switching valve or the third flow switching valve. The controller is designed to set the operating frequency of the compressor and set the degree of opening of the bypass expansion valve.

EFFECT: invention ensures operation of the flow switching differential valve under any conditions.

13 cl, 21 dwg

Description

Technical field

[0001] The present invention relates to a refrigeration cycle apparatus capable of operating in a heating mode, a defrosting mode, and a simultaneous heating-defrosting mode.

State of the art

[0002] In the 1st patent document, Fig. 1 shows an air conditioner. This air conditioner includes an outdoor heat exchanger including a first heat exchanger and a second heat exchanger. In this air conditioner, the outdoor heat exchanger can be subjected to defrosting without stopping heating by alternately defrosting the first heat exchanger and the second heat exchanger. This air conditioner is provided with two flow switching valves to allow the high temperature high pressure refrigerant to flow from the compressor to the first heat exchanger and the second heat exchanger. Said flow switching valves are formed by three-way valves using four-way valves.

Link List

Patent Documents

[0003]

1st patent document: WO 2017/094148

The essence of the invention

Technical problem

[0004] In an air conditioner, a differential valve is typically used as a flow switching valve. The differential valve includes, for example, a high pressure port connected to the discharge side of the compressor and a low pressure port connected to the suction side of the compressor, and operates using a pressure difference between high pressure and low pressure. The differential valve is set to a minimum operating differential pressure for reliable valve operation. If the pressure difference between high pressure and low pressure becomes less than or equal to the minimum operating differential pressure, the valve does not operate normally and does not switch the flow path.

[0005] The present invention has been made to solve the above problem, and it is an object of the present invention to provide a device for performing a refrigeration cycle that allows a differential pressure controlled flow switching valve to operate normally in a refrigerant circuit that is capable of operating in heating mode, defrost mode, and simultaneous heating and defrosting.

Solution

[0006] An apparatus for performing a refrigeration cycle according to an embodiment of the present invention includes a first flow switch valve, including a first port, a second port, a third port, and a fourth port, a second flow switch valve, and a third flow switch valve, each including a fifth port, a sixth an orifice and a seventh orifice, wherein said second flow switching valve and said third flow switching valve operate by means of differential pressure, a compressor including a refrigerant suction inlet and a refrigerant outlet, an outlet pipe providing a connection between said outlet and the first orifice , a suction pipe providing a connection between said suction hole and a second hole, a first high pressure pipe providing a connection between said exhaust pipe and the fifth hole of the second switch valve flow and the fifth hole of the third flow switching valve, a second high pressure pipe connecting the third hole with a branch located in the first high pressure pipe, a bypass expansion valve provided in the section of the first high pressure pipe, and the said section extends between the said outlet pipe and the mentioned branching, a valve provided in the second high pressure pipe, a low pressure pipe providing connection between said suction pipe and the sixth hole of the second flow switch valve and the sixth hole of the third flow switch valve, the first external heat exchanger connected to the seventh hole of the second flow switch valve, the second an outdoor heat exchanger connected to the seventh port of the third flow switching valve, an indoor heat exchanger connected to the fourth port, and a controller configured to control the compressor operating frequency and opening degree of the bypass expansion valve. Said controller is configured to perform a differential pressure guarantee process upon switching of the second flow switching valve or the third flow switching valve. In the above differential pressure guarantee process, the controller is configured to set the compressor operation frequency to the first frequency, and set the opening degree of the bypass expansion valve to the first degree if the first condition is not met, and set the compressor operation frequency to the second frequency which is higher than said first frequency, or setting the opening degree of the bypass expansion valve to a second degree which is higher than said first degree if said first condition is met.

The refrigeration cycle apparatus according to an embodiment of the present invention includes a first flow switching valve, including a first port, a second port, a third port, and a fourth port, a second flow switching valve, and a third flow switching valve, each including a fifth port, a sixth port, and a seventh port. an orifice, wherein said second flow switching valve and said third flow switching valve operate by differential pressure, a compressor including a refrigerant suction inlet and a refrigerant outlet, an exhaust pipe providing a connection between said outlet and the first orifice, a suction pipe , providing a connection between said suction port and the second port, a first high pressure pipe providing a connection between said outlet pipe and the fifth port of the second switching valve outlet and the fifth opening of the third flow switching valve, a second high pressure pipe connecting the third opening with a branch located in the first high pressure pipe, a bypass expansion valve provided in the section of the first high pressure pipe, said section extending between said outlet pipe and said branch , a valve provided in the second high pressure pipe, a low pressure pipe providing connection between said suction pipe and the sixth hole of the second pressure switch valve and the sixth hole of the third pressure switch valve, the first outdoor heat exchanger connected to the seventh hole of the second pressure switch valve, the second outdoor a heat exchanger connected to the seventh port of the third pressure switching valve; and an internal heat exchanger connected to the fourth port. Said bypass expansion valve includes a flow path allowing refrigerant to flow through it even if the bypass expansion valve is in the closed position.

Useful effects of the invention

[0007] According to an embodiment of the present invention, the minimum operating differential pressures of the second flow switching valve and the third flow switching valve, which are driven by the differential pressure, can be guaranteed by performing a differential pressure guarantee process when switching the second flow switching valve or the third valve flow switching. Therefore, the second flow switching valve and the third flow switching valve can operate normally under any condition.

Brief description of the drawings

[0008]

Fig. 1 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus according to the 1st embodiment.

2 is a functional block diagram of a controller according to the 1st embodiment.

Fig. 3 is a sectional view showing a schematic configuration of a four-way valve of a refrigeration cycle apparatus according to the 1st embodiment.

4 is a diagram showing the operation of the refrigeration cycle apparatus according to Embodiment 1 in a heating mode.

5 is a diagram showing the operation of the refrigeration cycle apparatus according to the 1st embodiment in a defrosting mode.

Fig. 6 is a diagram showing the operation of the refrigeration cycle apparatus according to the 1st embodiment during the first operation in the simultaneous heating-defrosting mode.

Fig. 7 is a diagram showing the operation of the refrigeration cycle apparatus according to the 1st embodiment during the second operation in the simultaneous heating-defrosting mode.

Fig. 8 is a flowchart showing the operation of the apparatus for performing the refrigeration cycle according to the 1st embodiment.

Fig. 9 is a table showing an example of the relationship between the second flow switching valve pressure and the outside air temperature in the 1st embodiment.

Fig. 10 is a table showing an example of the relationship between the second flow switching valve pressure and the compressor operating frequency in the 1st embodiment.

Fig. 11 is a flowchart showing a differential pressure guarantee process flow of the 1st embodiment.

12 is a table showing an example of the relationship between the second flow switching valve pressure and the outside air temperature in the 2nd embodiment.

Fig. 13 is a table showing an example of the relationship between the second flow switching valve pressure and the compressor operating frequency in the 2nd embodiment.

Fig. 14 is a flowchart showing the flow of the simultaneous heating-defrosting mode of the 2nd embodiment.

15 is a schematic drawing of a bypass expansion valve of the refrigeration cycle apparatus according to the 3rd embodiment.

Fig. 16 is a plan view of a bypass expansion valve seat according to the 3rd embodiment.

17 is a sectional view of a restriction portion of the bypass expansion valve according to the 3rd embodiment.

Fig. 18 is a sectional view of the restriction portion in the case where the bypass expansion valve according to the 3rd embodiment is in the closed position.

Fig. 19 is a sectional view of a restriction portion of the bypass expansion valve according to the modification of the 3rd embodiment.

20 is a sectional view of a restriction portion of a bypass expansion valve according to another modification of the 3rd embodiment.

Fig. 21 is a graph showing the relationship between the opening degree and the capacity Cv in the bypass expansion valve.

Description of Embodiments

[0009]

1st Embodiment

The refrigeration cycle apparatus 1 according to the 1st embodiment will be described below. 1 is a refrigerant circuit diagram showing the configuration of the refrigeration cycle apparatus 1 according to the 1st embodiment. In Embodiment 1, an air conditioner is shown as an example of the refrigeration cycle apparatus 1. As shown in FIG. 1, the refrigeration cycle apparatus 1 according to Embodiment 1 includes a refrigerant circuit 10 and a controller 50 that controls the refrigerant circuit 10. According to the 1st embodiment, the refrigerant circuit 10 includes a compressor 11, a first flow switch valve 12, an indoor heat exchanger 13, an expansion valve 14, a first outdoor heat exchanger 15a, a second outdoor heat exchanger 15b, a second flow switch valve 21a, and a third flow switch valve 21b . As will be described below, the refrigerant circuit 10 is capable of operating in at least a heating mode, a reverse cycle defrost mode (hereinafter simply referred to as a defrosting mode), and a simultaneous heating-defrosting mode. The refrigerant circuit 10 may also be configured to operate in a cooling mode. In the refrigeration mode, the first flow switch valve 12, the second flow switch valve 21a, and the third flow switch valve 21b are set to a position that substantially corresponds to the position for the defrost mode.

[0010] The refrigeration cycle device 1 includes an outdoor unit located outside the room and an indoor unit located inside the room. The outdoor unit includes a compressor 11, a first flow switch valve 12, an expansion valve 14, a first outdoor heat exchanger 15a, a second outdoor heat exchanger 15b, a second flow switch valve 21a, and a third flow switch valve 21b. The indoor unit includes an indoor heat exchanger 13.

[0011] The compressor 11 is a pneumatic machine that sucks in and compresses the low pressure refrigerant gas to discharge the high pressure refrigerant gas. The compressor 11 uses an inverter compressor capable of adjusting the operating frequency. The operating frequency range in the compressor 11 is set. The compressor 11 is designed to operate in accordance with the control carried out by the controller 50, with an operating frequency that can be changed within the said operating frequency range. The compressor 11 includes a suction port 11a for sucking in refrigerant and an outlet port 11b for discharging compressed refrigerant. The suction port 11a is maintained at a suction pressure, that is, a low pressure. The outlet 11b is maintained at the discharge pressure, that is, high pressure.

[0012] The first flow switching valve 12 is a four-way valve and has four ports E, F, G, and H. In the following description, port G, port E, port F, and port H may also be referred to as first port G, second port E, the third hole F and the fourth hole H, respectively. The first port G is a high pressure port, the pressure of which is kept high in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The second hole E is a low pressure hole, the pressure of which is kept low in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The first flow switching valve 12 may be in a first position, shown in solid line in FIG. 1, and a second position, shown in dashed line in FIG. In the first position, the first port G communicates with the fourth port H and the second port E communicates with the third port F. In the second position, the first port G communicates with the third port F and the second port E communicates with the fourth port H. The first flow switch valve 12 is installed to the first position in the heating mode and in the simultaneous heating-defrosting mode, and to the second position in the defrosting mode in accordance with the control performed by the controller 50.

[0013] The indoor heat exchanger 13 is a heat exchanger that performs heat exchange between the refrigerant flowing inside it and the air supplied by an indoor fan (not shown) housed in the indoor unit. The internal heat exchanger 13 acts as a condenser in heating mode and as an evaporator in cooling mode.

[0014] The expansion valve 14 is a valve that reduces the pressure of the refrigerant. As the expansion valve 14, an electronic expansion valve is used, which is capable of changing its opening degree in accordance with the control by the controller 50.

[0015] The first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are each a heat exchanger that exchanges heat between the refrigerant flowing therein and the air supplied by an outdoor fan (not shown) housed in the outdoor unit. The first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b serve as an evaporator in the heating mode and as a condenser in the cooling mode. In the refrigerant circuit 10, the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are connected in parallel to each other. The first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are formed, for example, by dividing one heat exchanger into two parts, upper and lower. For example, the first heat exchanger 15a is located below the second heat exchanger 15b. In this case, the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are also arranged parallel to each other with respect to the air flow.

[0016] The second flow switching valve 21a is a four-way valve and has four ports I, J, K, and L. In the following description, port K, port I, port L, and port J may also be referred to as the fifth port K, the sixth port I, the seventh hole L and the eighth hole J, respectively. The fifth hole K is a high-pressure hole, the pressure of which is kept high in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The sixth hole I is a low pressure hole, the pressure of which is kept low in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The eighth port J is closed so that the refrigerant does not flow out of the eighth port J. The second flow switch valve 21a may be in a first position shown in solid line in FIG. 1 and a second position shown in dashed line in FIG. In the first position, the fifth port K communicates with the eighth port J, and the sixth port I communicates with the seventh port L. In the second position, the fifth port K communicates with the seventh port L, and the sixth port I communicates with the eighth port J. The second flow switch valve 21a is installed to the first position in the heating mode, to the second position in the defrosting mode, and to the first position or the second position in the simultaneous heating-defrosting mode in accordance with the control performed by the controller 50.

[0017] The third flow switching valve 21b is a four-way valve and has four ports M, N, O, and P. In the following description, port O, port M, port P, and port N may also be referred to as fifth port O, sixth port M, the seventh hole P and the eighth hole N, respectively. The fifth port O is a high-pressure port, the pressure of which is kept high in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The sixth port M is a low-pressure port in which the pressure is kept low in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode. The eighth port N is closed so that refrigerant does not flow out of the eighth port N. The third flow switch valve 21b may be in a first position shown in solid line in FIG. 1 and a second position shown in dashed line in FIG. In the first position, the fifth port O communicates with the eighth port N and the sixth port M communicates with the seventh port P. In the second position, the fifth port O communicates with the seventh port P and the sixth port M communicates with the eighth port N. The third flow switch valve 21b is installed to the first position in the heating mode, to the second position in the defrosting mode, and to the first position or the second position in the simultaneous heating-defrosting mode in accordance with the control performed by the controller 50.

[0018] The first flow switching valve 12, the second flow switching valve 21a, and the third flow switching valve 21b are each a differential pressure controlled four-way valve, said four-way valve operating using the pressure difference between the pressure on the discharge side and the pressure on the suction side of the compressor 11. As the first flow switching valve 12, the second flow switching valve 21a, and the third flow switching valve 21b, four-way valves having the same configuration can be used.

[0019] The outlet port 11b of the compressor 11 and the first port G of the first flow switch valve 12 are connected by an outlet pipe 61. The high pressure refrigerant discharged from the outlet port 11b of the compressor 11 moves through the outlet pipe 61 in any of the heating mode, the defrost mode, and the simultaneous heating-defrosting. The suction port 11a of the compressor and the second port E of the first flow switch valve 12 are connected by a suction pipe 62. The low pressure refrigerant sucked into the suction port 11a of the compressor 11 moves through the suction pipe 62 in any of the heating mode, the defrosting mode, and the simultaneous heating-defrosting mode.

[0020] One end of the first high pressure pipe 67 is connected to a branch 63 located partially along the outlet pipe 61. The other end of the first high pressure pipe 67 in the branch 68 is divided into the first high pressure pipe 67a and the first high pressure pipe 67b. The first high pressure pipe 67a is connected to the fifth port K, which is a high pressure port, of the second flow switch valve 21a. The first high pressure pipe 67b is connected to the fifth port O, which is a high pressure port, of the third flow switch valve 21b.

[0021] The first high pressure pipe 67 comprises another branch 65 located between the branch 63 and the branch 68. The branch 65 of the first high pressure pipe 67 and the third port F of the first flow switching valve 12 are connected by the second high pressure pipe 64.

[0022] The first high pressure pipe 67 includes a bypass expansion valve 18 located between the branch 63 and the branch 65. The bypass expansion valve 18 is an electronic expansion valve, the opening degree of which is set in accordance with the control exercised by the controller 50. The bypass expansion valve 18 performs as well as the refrigerant pressure reduction function. The operation of the bypass expansion valve 18 will be described below.

[0023] The second high pressure pipe 64 includes a check valve 22. The check valve 22 is configured to allow the refrigerant to move in the direction from the third port F of the first flow switch valve 12 to the first high pressure pipe 67 and to prevent the refrigerant from moving away from the first pipe 67 high pressure to the third port F. Instead of the check valve 22, an on/off valve such as a solenoid valve or a motorized valve that opens and closes in accordance with the control provided by the controller 50 can be used. described below.

[0024] One end of the low pressure pipe 70 is connected to a branch 69 located partially along the suction pipe 62. The other end of the low pressure pipe 70 in the branch 71 is divided into a low pressure pipe 70a and a low pressure pipe 70b. The low pressure pipe 70a is connected to the sixth port I, which is a low pressure port, of the second flow switch valve 21a. The low pressure pipe 70b is connected to the sixth port M, which is a low pressure port, of the third flow switch valve 21b.

[0025] The fourth port H of the first flow switching valve 12 is connected to one inlet/outlet of the indoor heat exchanger 13 by a refrigerant pipe 80 disposed therebetween. The refrigerant pipe portion 80 is formed by an extension pipe connecting the outdoor unit to the indoor unit. The refrigerant pipe 80 includes a stop valve, which is not shown, located between said extension pipe and the outdoor unit.

[0026] The other inlet/outlet of the indoor heat exchanger 13 is connected to one inlet/outlet of the expansion valve 14 by a refrigerant pipe 81 disposed therebetween. The refrigerant pipe portion 81 is formed by an extension pipe connecting the outdoor unit to the indoor unit. The refrigerant pipe 81 includes a stop valve, which is not shown, located between said extension pipe and the outdoor unit.

[0027] One end of the refrigerant pipe 82 is connected to the other inlet-outlet of the expansion valve 14. The other end of the refrigerant pipe 82 in branch 84 is divided into a refrigerant pipe 82a and a refrigerant pipe 82b. The refrigerant pipe 82a includes a pressure reducing device such as a capillary tube 17a. Pipe 82a is connected to one input-output of the first outdoor heat exchanger 15a. The refrigerant pipe 82b includes a pressure reducing device such as a capillary tube 17b. The refrigerant pipe 82b is connected to one inlet/outlet of the second outdoor heat exchanger 15b. That is, the other inlet/outlet of the expansion valve 14 is connected to one inlet/outlet of the first outdoor heat exchanger 15a and one inlet/outlet of the second outdoor heat exchanger 15b via a refrigerant pipe 82 disposed therebetween. One inlet/outlet of the first outdoor heat exchanger 15a is connected to one inlet/outlet of the second outdoor heat exchanger 15b via a refrigerant pipe 82a and a refrigerant pipe 82b disposed therebetween.

[0028] The other inlet/outlet of the first outdoor heat exchanger 15a is connected to the seventh port L of the second flow switch valve 21a by a refrigerant pipe 83a disposed therebetween. The other inlet/outlet of the second outdoor heat exchanger 15b is connected to the seventh port P of the third flow switch valve 21b by a refrigerant pipe 83b disposed therebetween. At least in the heating mode and in the defrosting mode, in the refrigerant circuit 10, the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are connected in parallel to each other.

[0029] The casing of the outdoor unit is provided with an outdoor air temperature sensor 91, which is configured to measure the temperature of the outdoor air around the outdoor unit. If the outdoor unit is located indoors, outside temperature refers to the air temperature around the outdoor unit. The first outdoor heat exchanger 15a is provided with a heat exchanger temperature sensor 92a which is configured to sense the temperature of the first outdoor heat exchanger 15a. The second outdoor heat exchanger 15b is provided with a heat exchanger temperature sensor 92b which is configured to sense the temperature of the second outdoor heat exchanger 15b. The outside air temperature sensor 91, the heat exchanger temperature sensor 92a, and the heat exchanger temperature sensor 92b are, for example, thermistors. The measurement results from the outdoor air temperature sensor 91, the heat exchanger temperature sensor 92a, and the heat exchanger temperature sensor 92b are transmitted to the controller 50 and used by the controller 50 for control. The refrigerant circuit 10 may include a temperature sensor or a pressure sensor in addition to the sensors described above.

[0030] The controller 50 includes a microcomputer including, for example, a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and an I/O port ( input/output - I/O). 2 is a functional block diagram of the controller 50 according to the 1st embodiment. As shown in FIG. 2, the controller 50 receives measurements from the outside air temperature sensor 91, the heat exchanger temperature sensor 92a, and the heat exchanger temperature sensor 92b. The controller 50 may also receive a measurement signal from said other temperature sensor and said other pressure sensor provided in the refrigerant circuit 10, and an operating control signal from an operating unit which receives input from the user.

[0031] The controller 50 includes a control block 501, a condition determination block 502, and a differential pressure guarantee block 503 as functional blocks implemented by executing programs. The controller 50 further includes a memory unit 504 including a storage device such as ROM or RAM. The operation control unit 501 controls the operation of the entire refrigeration cycle apparatus 1 based on input signals, and operates in a heating mode, a defrosting mode, and a simultaneous heating-defrosting mode. Specifically, the operation control unit 501 controls the operating frequency of the compressor 11, the opening degree of the expansion valve 14, the switching of the first flow switching valve 12, the switching of the second flow switching valve 21a and the switching of the third flow switching valve 21b, the opening degree of the bypass expansion valve 18, and the fan.

[0032] The condition determining unit 502 determines whether the first condition is met based on the measurement results from the outdoor air temperature sensor 91, the heat exchanger temperature sensor 92a, and the heat exchanger temperature sensor 92b when the second flow switch valve 21a and the third flow switch valve 21b are switched. If the condition determination unit 502 determines that the first condition is met, the differential pressure assurance unit 503 controls the opening degree of the bypass expansion valve 18 so as to guarantee a certain pressure difference. The condition determination block 502 and the differential pressure guarantee block 503 will be described in detail below. The memory unit 504 stores various kinds of data and programs used in processing by the operational control unit 501, the condition determination unit 502, and the differential pressure assurance unit 503.

[0033] FIG. 3 is a sectional view showing a schematic configuration of the second flow switching valve 21a of the refrigeration cycle apparatus 1 according to the 1st embodiment. As shown in FIG. 3, the second flow switch valve 21a includes a valve body 100 and an auxiliary solenoid valve 120. The second flow switch valve 21a is a differential pressure controlled four-way valve.

[0034] The valve body 100 includes a cylinder 101, a spool plate 102 formed at an inner wall portion of the cylinder 101, and a spool valve 103 that slides on the spool plate 102 along the direction of the central axis of the cylinder 101. The central part of the spool plate 102 in the direction of the central axis of the cylinder 101 contains a sixth hole I, which is a low pressure hole. The seventh hole L and the eighth hole J are located on both sides of the sixth hole I so that the sixth hole I is located between the seventh hole L and the eighth hole J in the direction of the central axis of the cylinder 101. The fifth hole K, which is a high pressure hole, is located opposite the sixth hole holes I across the central axis of the cylinder 101.

[0035] The spool valve 103 has the shape of a hemisphere, which is open near the spool mirror 102. On one end side of the spool valve 103 in the direction of the central axis of the cylinder 101 is a piston 104 connected to the spool valve 103. Between one end of the cylinder 101 and the piston 104 is formed a first cavity 106. On the other end side of the spool valve 103 in the direction of the central axis of the cylinder 101 is a piston 105 connected to the spool valve 103. A second cavity 107 is formed between the other end of the cylinder 101 and the piston 105. The pistons 104 and 105 are slidable along the surface the inner wall of the cylinder 101. The pistons 104 and 105 move together with the spool valve 103 along the direction of the central axis of the cylinder 101.

[0036] The auxiliary solenoid valve 120 is connected to the valve body 100 by four separate auxiliary pipelines 110, 111, 112 and 113 located between them. The auxiliary pipeline 110 is connected to the fifth hole K of the valve body 100 . The auxiliary pipeline 111 is connected to the sixth hole I of the valve body 100. The auxiliary pipeline 112 is connected to the first cavity 106 of the valve body 100. The auxiliary pipeline 113 is connected to the second cavity 107 of the valve body 100.

[0037] The auxiliary solenoid valve 120 switches between the first position and the second position in accordance with the control performed by the controller 50. In the first position, the auxiliary pipeline 110 communicates with the auxiliary pipeline 113 in the interior of the auxiliary solenoid valve 120, and the auxiliary pipeline 111 communicates with the auxiliary pipeline 112 in the interior of the auxiliary solenoid valve 120. Thus, in the first position, the fifth port K communicates with the second cavity 107 so that the pressure in the second cavity 107 becomes high, and the sixth port I communicates with the first cavity 106 so that the pressure in the first cavity 106 goes low. The spool valve 103 due to the pressure difference between the first cavity 106 and the second cavity 107 moves towards the first cavity 106 and comes to the position shown in Fig.3. As a result, the sixth hole I communicates with the seventh hole L, and the fifth hole K communicates with the eighth hole J.

[0038] In the second position, the auxiliary pipeline 110 communicates with the auxiliary pipeline 112 in the interior of the auxiliary solenoid valve 120, and the auxiliary pipeline 111 communicates with the auxiliary pipeline 113 in the interior of the auxiliary solenoid valve 120. Thus, in the second position, the fifth hole K communicates with the first cavity 106 so that the pressure in the first cavity 106 becomes high, and the sixth hole I communicates with the second cavity 107 so that the pressure in the second cavity 107 becomes low. The spool valve 103, due to the pressure difference between the first cavity 106 and the second cavity 107, moves towards the second cavity 107. As a result, the sixth hole I communicates with the eighth hole J, and the fifth hole K communicates with the seventh hole L.

[0039] In either of the first position and the second position, the pressure in the fifth port K is higher than the pressure in the sixth port I, and thus the spool valve 103 is pressed against the spool plate 102 by the pressure difference. 103.

[0040] Although not shown or described, the third flow switch valve 21b and the first flow switch valve 12 each have substantially the same configuration as the configuration of the second flow switch valve 21a.

[0041] The operation of the device 1 for performing the refrigeration cycle in the heating mode will be described below. 4 is a diagram showing the operation of the refrigeration cycle apparatus 1 according to the 1st embodiment in a heating mode. As shown in FIG. 4, in the heating mode, the first flow switch valve 12 is set to the first position, in which the first port G communicates with the fourth port H and the second port E communicates with the third port F. The second flow switch valve 21a is set to the first position. in which the fifth port K communicates with the eighth port J and the sixth port I communicates with the seventh port L. The third flow switch valve 21b is set to the first position, in which the fifth port O communicates with the eighth port N and the sixth port M communicates with the seventh port. hole R.

[0042] The bypass expansion valve 18 is set to the open position. In this case, the opening degree of the bypass expansion valve 18 corresponds to "fully open". When the bypass expansion valve 18 is in the open position, the pressure at the fifth port K of the second flow switch valve 21a and the pressure at the fifth port O of the third flow switch valve 21b are maintained at high pressure or intermediate pressure. In this case, the intermediate pressure is a pressure that is higher than the suction pressure of the compressor 11 and lower than the discharge pressure of the compressor 11. If the bypass expansion valve 18 is set to the open position, the end side of the first high pressure pipe 67 is blocked by the eighth hole J of the second flow switch valve 21a, and the eighth hole N of the third flow switch valve 21b. Thus, the refrigerant does not flow out from the other openings of the second flow switch valve 21a and the third flow switch valve 21b. Bypass expansion valve 18 can be set to the closed position. The pressure at the sixth port I of the second flow switch valve 21a and the pressure at the sixth port M of the third flow switch valve 21b are maintained at a low pressure. Thus, even when the bypass expansion valve 18 is set to the closed position, the pressure at the fifth port K of the second flow switch valve 21a is maintained higher than the pressure at the sixth port I, and the pressure at the fifth port O of the third flow switch valve 21b is maintained higher than the pressure in the sixth hole M.

[0043] The movement of the refrigerant in the direction from the first high pressure pipe 67 to the third port F of the first flow switch valve 12 is blocked by the stop valve 22. If an on/off valve is used instead of the stop valve 22, the on/off valve is set to the closed position. As a result, the movement of the refrigerant in the direction from the first high pressure pipe 67 to the third port F of the first flow switching valve 12 is blocked by the on/off valve.

[0044] The high-pressure refrigerant gas discharged from the compressor 11 moves to the indoor heat exchanger 13 through the exhaust pipe 61, the first flow switch valve 12, and the refrigerant pipe 80. In heating mode, the indoor heat exchanger 13 acts as a condenser. That is, in the indoor heat exchanger 13, heat exchange occurs between the refrigerant flowing in the indoor heat exchanger 13 and the room air supplied by the indoor fan, and the condensation heat of the refrigerant is transferred to the room air. As a result, the gaseous refrigerant which flows into the indoor heat exchanger 13 is converted into a high pressure liquid refrigerant. The room air supplied by the indoor fan is heated by the heat received from the refrigerant.

[0045] The liquid refrigerant that flows out of the indoor heat exchanger 13 moves through the refrigerant pipe 81 to the expansion valve 14. The liquid refrigerant that flows into the expansion valve 14 is converted into a two-phase low pressure refrigerant by pressure reduction. The two-phase refrigerant that flows out of the expansion valve 14 passes through the refrigerant pipe 82 and is separated to move into the refrigerant pipe 82a and the refrigerant pipe 82b. The two-phase refrigerant discharged into the refrigerant pipe 82a is further subjected to pressure reduction in the capillary tube 17a and then transferred to the first outdoor heat exchanger 15a. The two-phase refrigerant drawn into the refrigerant pipe 82b is further subjected to pressure reduction in the capillary tube 17b and then transferred to the second outdoor heat exchanger 15b.

[0046] In the heating mode, both the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b act as an evaporator. That is, in each of the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b, heat exchange takes place between the refrigerant flowing in the outdoor heat exchanger and the outdoor air supplied by the outdoor fan, and the evaporative heat of the refrigerant is absorbed from the outdoor air. As a result, the two-phase refrigerant that flows into each of the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b is vaporized to become a low pressure refrigerant gas.

[0047] The refrigerant gas that exits the first outdoor heat exchanger 15a moves through the refrigerant pipe 83a, the second flow switch valve 21a, the low pressure pipe 70a, the low pressure pipe 70, and the suction pipe 62, and is sucked into the compressor 11. The gaseous refrigerant that exits from the second outdoor heat exchanger 15b, moves through the refrigerant pipe 83b, the third flow switch valve 21b, and the low pressure pipe 70b, combines with the refrigerant gas that exits the first outdoor heat exchanger 15a, and is sucked into the compressor 11. That is, the refrigerant gas that exits the first outdoor heat exchanger 15a, and the gaseous refrigerant that exits the second outdoor heat exchanger 15b is sucked into the compressor 11 without passing through the first flow switch valve 12. The refrigerant gas sucked into the compressor 11 is compressed into a high pressure refrigerant gas. In heating mode, the above cycle is continuously repeated.

[0048] In the heating mode, the first port G of the first flow switch valve 12, the fifth port K of the second flow switch valve 21a, and the fifth port O of the third flow switch valve 21b are all maintained at high pressure or intermediate pressure. In the heating mode, the second port E of the first flow switch valve 12, the sixth port I of the second flow switch valve 21a, and the sixth port M of the third flow switch valve 21b are all maintained at low pressure.

[0049] The operation of the device 1 for performing the refrigeration cycle in the defrost mode will be described below. Fig. 5 is a diagram showing the operation of the cycle apparatus 1 for performing the refrigeration cycle according to the 1st embodiment in the defrosting mode. As shown in FIG. 5, in the defrosting mode, the first flow switch valve 12 is set to the second position, in which the first port G communicates with the third port F and the second port E communicates with the fourth port H. The second flow switch valve 21a is set to the second position. in which the fifth port K communicates with the seventh port L and the sixth port I communicates with the eighth port J. hole N.

[0050] The bypass expansion valve 18 is set to the closed position, for example. The movement of refrigerant in the direction from the third port F of the first flow switch valve 12 to the first high pressure pipe 67 is permitted by the stop valve 22. If an on/off valve is used instead of the stop valve 22, the on/off valve is set to the open position. As a result, movement of the refrigerant in the direction from the third port F of the first flow switching valve 12 to the first high pressure pipe 67 is allowed by the on/off valve.

[0051] The gaseous refrigerant discharged from the compressor 11 moves through the outlet pipe 61, the first flow switch valve 12, the second high pressure pipe 64 and the first high pressure pipe 67, and is separated to move into the first high pressure pipe 67a and the first high pressure pipe 67b . The gaseous refrigerant diverted to the first high pressure pipe 67a moves to the first outdoor heat exchanger 15a through the second flow switch valve 21a and the refrigerant pipe 83a. The refrigerant gas withdrawn to the first high pressure pipe 67b moves to the second outdoor heat exchanger 15b through the third flow switch valve 21b and the refrigerant pipe 83b. In the defrost mode, both the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b act as a condenser. That is, in the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b, the heat transferred from the refrigerant flowing in each of the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b melts the frost formed on the respective one of the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b. As a result, the first outdoor heat exchanger 15a and the second outdoor heat exchanger 15b are subjected to defrosting. The gaseous refrigerant which flows into the first outdoor heat exchanger 15a and the gaseous refrigerant which flows into the second outdoor heat exchanger 15b are condensed into a liquid refrigerant.

[0052] The liquid refrigerant that flows out of the first outdoor heat exchanger 15a is subjected to pressure reduction in the capillary tube 17a and through the refrigerant pipe 82a and the refrigerant pipe 82 moves to the expansion valve 14. The liquid refrigerant that flows out of the second outdoor heat exchanger 15b is subjected to pressure reduction in the capillary tube 17b, moves through the refrigerant pipe 82b, combines with the liquid refrigerant that flows out of the first outdoor heat exchanger 15a, and moves to the expansion valve 14. The liquid refrigerant that flows into the expansion valve 14 is converted into a two-phase low refrigerant by pressure reduction. pressure. The two-phase refrigerant that flows out of the expansion valve 14 moves through the refrigerant pipe 81 to the indoor heat exchanger 13. In the defrost mode, the indoor heat exchanger 13 acts as an evaporator. That is, in the indoor heat exchanger 13, the heat of vaporization of the refrigerant flowing in the indoor heat exchanger 13 is absorbed from the room air. As a result, the two-phase refrigerant that flows into the indoor heat exchanger 13 is vaporized to become a low-pressure gaseous refrigerant. The refrigerant gas that flows out from the indoor heat exchanger 13 passes through the refrigerant pipe 80, the first flow switch valve 12 and the suction pipe 62, and is sucked into the compressor 11. The refrigerant gas sucked into the compressor 11 is subjected to compression to become a high pressure refrigerant gas. In the defrost mode, the above cycle is continuously repeated.

[0053] In the defrosting mode, the first port G of the first flow switch valve 12, the fifth port K of the second flow switch valve 21a, and the fifth port O of the third flow switch valve 21b are all maintained at high pressure. In the defrosting mode, the second port E of the first flow switch valve 12, the sixth port I of the second flow switch valve 21a, and the sixth port M of the third flow switch valve 21b are all kept at low pressure.

[0054] The operation of the device 1 for performing the refrigeration cycle in the simultaneous heating-defrosting mode will be described below. The simultaneous heating-defrosting mode includes a first operation and a second operation. During the first operation, the first outdoor heat exchanger 15a and the indoor heat exchanger 13 act as a condenser, and the second outdoor heat exchanger 15b acts as an evaporator. As a result, the first outdoor heat exchanger 15a undergoes defrosting while continuing heating. During the second operation, the second outdoor heat exchanger 15b and the indoor heat exchanger 13 act as a condenser, and the first outdoor heat exchanger 15a acts as an evaporator. As a result, the second outdoor heat exchanger 15b undergoes defrosting while continuing heating. Fig. 6 is a diagram showing the operation of the refrigeration cycle apparatus 1 according to the 1st embodiment during the first operation in the simultaneous heating-defrosting mode.

[0055] As shown in Fig. 6, during the first operation, the first flow switching valve 12 is set to the first position in which the first port G communicates with the fourth port H and the second port E communicates with the third port F. The second switch valve 21a is set to the second position where the fifth port K communicates with the seventh port L and the sixth port I communicates with the eighth port J. hole M is connected by the seventh hole P.

[0056] The bypass expansion valve 18 is set to the open position at a predetermined degree of opening. The movement of the refrigerant in the direction from the first high pressure pipe 67 to the third port F of the first flow switch valve 12 is blocked by the stop valve 22. If an on/off valve is used instead of the stop valve 22, the on/off valve is set to the closed position. As a result, the movement of the refrigerant in the direction from the first high pressure pipe 67 to the third port F of the first flow switching valve 12 is blocked by the on/off valve.

[0057] Part of the high pressure refrigerant gas discharged from the compressor 11 is diverted from the outlet pipe 61 to the first high pressure pipe 67 . The gaseous refrigerant, which is diverted to the first high pressure pipe 67, is subjected to pressure reduction in the bypass expansion valve 18 to be at an intermediate pressure, and through the first high pressure pipe 67a, the second flow switching valve 21a and the refrigerant pipe 83a is transferred to the first outdoor heat exchanger 15a . In the first outdoor heat exchanger 15a, the heat transferred from the refrigerant flowing in the first outdoor heat exchanger 15a melts the frost formed on the first outdoor heat exchanger 15a. As a result, the first outdoor heat exchanger 15a is subjected to defrosting. The gaseous refrigerant that moves to the first outdoor heat exchanger 15a is condensed into an intermediate pressure liquid or two-phase refrigerant, flows out of the first outdoor heat exchanger 15a, and undergoes pressure reduction in the capillary tube 17a.

[0058] The high-pressure refrigerant gas discharged from the compressor 11, part of which is diverted to the first high-pressure pipe 67, moves to the indoor heat exchanger 13 through the first flow switch valve 12 and the refrigerant pipe 80. In the indoor heat exchanger 13, heat is exchanged between the refrigerant flowing in the indoor heat exchanger 13 and the room air supplied by the indoor fan, and the condensation heat of the refrigerant is transferred to the room air. As a result, the gaseous refrigerant that moves to the indoor heat exchanger 13 is condensed into a high pressure liquid refrigerant. The room air supplied by the indoor fan is heated by the heat received from the refrigerant.

[0059] The liquid refrigerant that flows out of the indoor heat exchanger 13 moves through the refrigerant pipe 81 to the expansion valve 14. The liquid refrigerant that flows into the expansion valve 14 is converted into a two-phase low pressure refrigerant by pressure reduction. The two-phase refrigerant that flows out of the expansion valve 14 passes through the refrigerant pipe 82, combines with the liquid or two-phase refrigerant subjected to pressure reduction in the capillary tube 17a, is further subjected to pressure reduction in the capillary tube 17b, and moves to the second outdoor heat exchanger 15b. In the second outdoor heat exchanger 15b, heat exchange occurs between the refrigerant flowing in the second outdoor heat exchanger 15b and the outdoor air supplied by the outdoor fan, and the heat of evaporation of the refrigerant is absorbed from the outdoor air. As a result, the two-phase refrigerant that moves to the second outdoor heat exchanger 15b is vaporized to become a low-pressure gaseous refrigerant. The refrigerant gas that flows out from the second outdoor heat exchanger 15b moves through the refrigerant pipe 83b, the third flow switch valve 21b, the low pressure pipe 70b, the low pressure pipe 70, and the suction pipe 62, and is sucked into the compressor 11. That is, the refrigerant gas that flows out from of the second outdoor heat exchanger 15b is sucked into the compressor 11 without passing through the first flow switch valve 12. The refrigerant gas sucked into the compressor 11 is compressed into a high pressure refrigerant gas. During the first operation in the simultaneous heating-defrosting mode, the first outdoor heat exchanger 15a is subjected to defrosting, and heating is continued by continuously repeating the above-described cycle.

[0060] During the first operation in the simultaneous heating-defrosting mode, the first port G of the first flow switch valve 12, the fifth port K of the second flow switch valve 21a, and the fifth port O of the third flow switch valve 21b are all maintained at high pressure or intermediate pressure. During the first operation, the second port E of the first flow switch valve 12, the sixth port I of the second flow switch valve 21a, and the sixth port M of the third flow switch valve 21b are all maintained at low pressure.

[0061] FIG. 7 is a diagram showing the operation of the refrigeration cycle apparatus 1 according to the 1st embodiment during the second operation in the simultaneous heating-defrosting mode. As shown in FIG. 7, during the second operation in the simultaneous heating-defrosting mode, unlike the first operation, the second flow switching valve 21a is set to the first position, and the third flow switching valve 21b is set to the second position. The first flow switching valve 12 and the bypass expansion valve 18 are set to the same positions as in the first operation. As a result, during the second operation, the second outdoor heat exchanger 15b undergoes defrosting while continuing heating. During the second operation, the first port G of the first flow switch valve 12, the fifth port K of the second flow switch valve 21a, and the fifth port O of the third flow switch valve 21b are all maintained at high pressure or intermediate pressure. During the second operation, the second port E of the first flow switch valve 12, the sixth port I of the second flow switch valve 21a, and the sixth port M of the third flow switch valve 21b are maintained at low pressure.

[0062] FIG. 8 is a flowchart showing the operation of the device 1 for performing the refrigeration cycle according to the 1st embodiment. The operation control unit 501 of the controller 50 starts the heating mode based on, for example, the heating operation start signal from the operation unit (S1). When starting the heating mode, the operation control unit 501 determines whether the defrost determination condition (S2) is met. Said defrost determination condition may be, for example, when the period of time elapsed from the start of the heating mode exceeds the time limit (eg, 20 minutes). If it is determined that the defrost determination condition is satisfied (S2: YES), the process proceeds to the processing in S3. On the other hand, if it is determined that the defrost determination condition is not met (S2: NO), the processing in S2 is periodically repeated.

[0063] In step S3, the operating control unit 501 takes as the operating frequency f the operating frequency value of the compressor 11 at the present time, or the average operating frequency of the compressor 11 from the start of the heating mode to the present time. The controller 50 then determines whether the frequency difference value (fmax - f) is indeed greater than or equal to the limit value fth, said frequency difference value being obtained by subtracting the operating frequency f from the maximum operating frequency fmax of the compressor 11 (S3). In this case, the maximum operating frequency fmax is the upper limit value of the operating frequency range of the compressor 11. The maximum operating frequency fmax and the limit value fth are preset in the ROM of the controller 50. The compressor 11 is controlled in such a way that the higher the thermal load, the higher the operating frequency, and hence the operating frequency of the compressor 11 is generally proportional to the heat load.

[0064] If the value obtained by subtracting the operating frequency f from the maximum operating frequency fmax is greater than or equal to the limit value fth (fmax-f≥fth)(S3:YES), then the process proceeds to the processing in step S4. On the other hand, if the value obtained by subtracting the operating frequency f from the maximum operating frequency fmax is smaller than the limit value fth (fmax-f˂fth)(S3:NO), the process proceeds to the processing in step S7.

[0065] In step S4, before switching from the heating mode to the simultaneous heating-defrosting mode, the condition determination unit 502 and the differential pressure assurance unit 503 carry out the differential pressure assurance process (S4). The contents of the differential pressure assurance process will be described in detail below. After the differential pressure guarantee process, the operating control unit 501 operates in the simultaneous heating-defrosting mode for a predetermined period of time (S5). In the simultaneous heating-defrosting mode, first, a first operation is performed in which the first outdoor heat exchanger 15a is subjected to defrosting, and then a second operation is performed in which the second outdoor heat exchanger 15b is subjected to defrosting. In this case, the operating control unit 501 contains a counter that stores the number of times N how many simultaneous heating-defrosting operations have been performed. The initial value of the counter is zero. If simultaneous heating-defrosting operation is performed, the operation control unit 501 adds one to the number of times N stored in the counter.

[0066] Then, the operation control unit 501 determines whether the number of times N, how many simultaneous heating-defrost operations have been performed, is greater than or equal to the limit value Nth corresponding to the number of times (S6). If the number of times N is greater than or equal to the limit value Nth corresponding to the number of times (N≥Nth)(S6:YES), then the process proceeds to the processing in step S8. Before proceeding to the processing in step S8, heating operation may be performed. If, on the other hand, the number of times Nth is less than the limit value Nth corresponding to the number of times (N˂Nth)(S6:NO), the process returns to step S1 and the heating operation is restarted.

[0067] In step S7, the operating control unit 501 continues the heating mode for a predetermined period of time. Then, the process proceeds to the processing in step S8. In step S8, the controller 50 ends the heating mode or the simultaneous heating-defrosting mode and performs the defrosting mode for a predetermined period of time. In general, the period during which defrosting operation is performed is shorter than the period during which simultaneous heating-defrosting operation is performed. In addition, if the operation control unit 501 has performed the defrost operation, the operation control unit 501 turns on the counter and sets the number of times N that the simultaneous heating-defrost operation has been performed to zero. After the operation control unit 501 has completed the defrost operation, the process returns to step S1, and the operation control unit 501 restarts the heating operation.

[0068] The differential pressure assurance process in the 1st embodiment will be described below. In the following, the second flow switching valve 21a will be described as an example of the differential pressure valve, however, the first flow switching valve 12 and the third flow switching valve 21b have the same configuration as the second flow switching valve 21a. The second flow switching valve 21a is set to a minimum operating differential pressure required for actuation. If the difference between the refrigerant pressure in the fifth port K, which is the high pressure port of the second flow switch valve 21a, and the refrigerant pressure in the sixth port I, which is the low pressure port of the second flow switch valve 21a, becomes less than or equal to the minimum operating differential pressure, then the second flow switch valve 21a does not operate. The phrase "the second flow switching valve 21 does not work" means that the opening switching does not occur or a stall occurs when the opening switching stops halfway. The minimum operating differential pressure varies depending on the specifications of the second flow switching valve 21a, and ranges from 0.1 MPa to 0.2 MPa, for example. Under normal operating conditions, the minimum operating differential pressure of the second flow switching valve 21a is guaranteed, however, there is a case where the minimum operating differential pressure cannot be guaranteed under specific conditions.

[0069] FIG. 9 is a table showing an example of the relationship between the pressure in the second flow switching valve 21a and the outside air temperature in the 1st embodiment. The table in FIG. 9 shows the pressures in the second flow changeover valve 21a in heating mode when the bypass expansion valve 18 is closed. It is assumed that the minimum operating differential pressure of the second flow switching valve 21a is 0.20 MPa. The outdoor air saturation pressure is the saturation pressure corresponding to the outdoor air temperature and corresponds to the refrigerant pressure at the high pressure port (fifth port K) of the second flow switch valve 21a. The suction pressure is the pressure corresponding to the suction saturation temperature obtained by subtracting the temperature difference between the outdoor air temperature and the heat exchanger temperature from the outdoor air temperature, and corresponds to the pressure of the refrigerant at the low pressure port (sixth port I) of the second flow switch valve 21a. The bypass limit pressure is obtained by adding the minimum operating differential pressure to the suction pressure, and is the pressure at the high pressure port required to actuate the second flow switching valve 21a. The deviation corresponds to the values obtained by subtracting the saturation pressure of the outside air from the bypass pressure limit. In other words, the deviation is the difference between the high pressure orifice pressure required to guarantee the minimum operating differential pressure of the second flow switching valve 21a and the actual pressure at the high pressure orifice. If said deviation has a negative value, then the minimum operating differential pressure can be guaranteed. However, if said deviation is positive, the minimum operating differential pressure cannot be guaranteed.

[0070] As shown in Fig. 9, it is obvious that the lower the outside air temperature, the greater this deviation. Specifically, if the outdoor air temperature is 5°C, then the deviation is 0.062 MPa. If the outside air temperature is -15°C, then the deviation is 0.118 MPa. That is, if the outdoor air temperature is -15°C, compared with the case in which the outdoor air temperature is 5°C, if the pressure in the high pressure port is not increased, the minimum operating differential pressure of the second flow switch valve 21a cannot be guaranteed.

[0071] FIG. 10 is a table showing an example of the relationship between the pressure in the second flow switching valve 21a and the operating frequency of the compressor 11 in the 1st embodiment. The table in FIG. 10 shows the pressures in the second flow changeover valve 21a in heating mode when the bypass expansion valve 18 is closed. It is assumed that the minimum operating differential pressure of the second flow switching valve 21a is 0.20 MPa. The compressor 11 is controlled so that the higher the heat load, the higher the operating frequency, and accordingly the operating frequency of the compressor 11 is generally proportional to the heat load. The heat load is usually proportional to the temperature difference between the outside temperature and the heat exchanger temperature. The heat exchange temperature is, for example, the average of the temperature of the first outdoor heat exchanger 15a measured by the heat exchanger temperature sensor 92a and the temperature of the second outdoor heat exchanger 15b measured by the heat exchanger temperature sensor 92b. It is noted that the heat exchanger temperature may be either the temperature of the first outdoor heat exchanger 15a or the temperature of the second outdoor heat exchanger 15b. In Fig. 10, it is assumed that the temperature difference between the outdoor air temperature and the heat exchanger temperature represents the operating frequency of the compressor 11.

[0072] The outside air saturation pressure is the saturation pressure corresponding to the outside air temperature and corresponds to the refrigerant pressure at the high pressure port (fifth port K) of the second flow switch valve 21a. The suction pressure is the pressure corresponding to the suction saturation temperature obtained by subtracting the temperature difference between the outdoor air temperature and the heat exchanger temperature from the outdoor air temperature, and corresponds to the pressure of the refrigerant at the low pressure port (sixth port I) of the second flow switch valve 21a. The bypass limit pressure is obtained by adding the minimum operating differential pressure to the suction pressure, and is the pressure at the high pressure port required to actuate the second flow switching valve 21a. The deviation corresponds to the difference between the bypass limit pressure and the outside air saturation pressure. In other words, the deviation is the difference between the high pressure orifice pressure required to guarantee the minimum operating differential pressure of the second flow switching valve 21a and the actual pressure at the high pressure orifice. If said deviation has a negative value, then the minimum operating differential pressure can be guaranteed. However, if said deviation is positive, the minimum operating differential pressure cannot be guaranteed.

[0073] As shown in FIG. 10, it is clear that the smaller the difference between the outside air temperature and the heat exchanger temperature, that is, the lower the operating frequency of the compressor 11, the larger the deviation. Specifically, if the outdoor air temperature is 2°C and the temperature difference is 15°C, then the deviation is -0.142 MPa, and the minimum working differential pressure can be guaranteed. If the temperature difference is 5°C, then the deviation is 0.072 MPa, and the minimum working differential pressure cannot be guaranteed. That is, if the outdoor air temperature is 2°C and the temperature difference is 5°C, compared with the case in which the temperature difference is 15°C, if the pressure in the high pressure port is not increased, then the minimum working differential pressure of the second valve 21a, stream switching is not possible.

[0074] Based on the above, if the outdoor air temperature is low or if the temperature difference between the outdoor air temperature and the heat exchanger temperature is small, that is, if the operating frequency of the compressor 11 is low, then there may be a case where the minimum operating differential pressure of the second flow switching valve 21a is guaranteed impossible. In the 1st embodiment, the case where the outdoor air temperature is low or the case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is small, that is, the case where the operation frequency of the compressor 11 is low, is considered as the first condition. If the first condition is met, then the opening degree of the bypass expansion valve 18 is controlled so as to increase the pressure in the high pressure port.

[0075] Fig. 11 is a flowchart showing a differential pressure guarantee process flow of the 1st embodiment. This process is carried out by the condition determination unit 502 and the differential pressure assurance unit 503 of the controller 50. In this algorithm, the outside air temperature is first determined by the outside air temperature sensor 91 (S101). The temperature difference between the outdoor air temperature and the heat exchanger temperature is calculated by the condition determining unit 502 (S102). Specifically, the temperature of the first outdoor heat exchanger 15a is measured by the heat exchanger temperature sensor 92a, and the temperature of the second outdoor heat exchanger 15b is measured by the heat exchanger temperature sensor 92b. The heat exchanger temperature is calculated as the average of these temperatures. The temperature difference between the outside temperature and the heat exchanger temperature is then calculated.

[0076] Then, the condition determination block 502 determines whether the first condition is met (S103). The first condition corresponds, for example, to the case where the outdoor air temperature is less than or equal to the first limit value, or to the case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the second limit value. The first limit value and the second limit value are set in advance and stored in the memory unit 504 of the controller 50. For example, the first limit value is 0°C. As shown in Fig. 9, if the outdoor air temperature is less than or equal to 5°C, then the deviation is positive. Thus, the temperature, which is set arbitrarily and is less than or equal to 5°C, can be considered as the first limit value. The second limit value is, for example, 8.05°C. As shown in FIG. 10, if the outdoor air temperature is 2° C. with a temperature difference between the outdoor air temperature and the heat exchanger temperature equal to 8.05° C., then the deviation is zero. As a result, even if the outdoor air temperature is higher than 0°C when the temperature difference is less than 8.05°C, the minimum operating differential pressure cannot be guaranteed. Thus, the second limit value is set to 8.05°C.

[0077] It is noted that the first condition is not limited to the above. For example, the first condition may only correspond to the case where the outdoor air temperature is less than or equal to the first limit value. Alternatively, the first condition may only correspond to the case where the temperature difference between the outside air temperature and the heat exchanger temperature is less than or equal to the second limit value. In addition, the first condition may correspond to the case where the outdoor air temperature is less than or equal to the first limit value, and the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the second limit value. In addition, when the first condition includes a case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the second limit value, a plurality of second limit values can be set in accordance with the outdoor air temperature. For example, in the example shown in FIG. 10, when the outdoor temperature is between 0°C and 5°C, the second limit value may be 8°C when the outdoor temperature is between 0°C and - 5°C, the second limit value may be 9.85°C, and when the outdoor air temperature is between -5°C and -10°C, the second limit value may be 11.55°C. Any of the mentioned second limit values can be selected according to the outside air temperature. The first limit value and the second limit value are appropriately set in accordance with the minimum operating differential pressure of the second flow switch valve 21a and the specifications and operating conditions of the refrigeration cycle apparatus 1, and are not limited to the above-described examples.

[0078] If the first condition is not met (S103: NO), then the opening degree of the bypass expansion valve 18 is set to the predetermined first degree (S104). On the other hand, if the first condition is met (S103: YES), the opening degree of the bypass expansion valve 18 is set to the second degree, which is larger than the first degree, by the differential pressure assurance unit 503 (S105). For example, the second power is 1.5 times larger than the first power. As a result, the differential pressure guarantee process is completed, the second flow switching valve 21a is switched, and the first simultaneous heating-defrosting operation is performed in step S6 according to FIG. Here, in situations where the first condition is met, that is, in situations where the minimum operating differential pressure of the second flow switching valve 21a is not guaranteed, the opening degree of the bypass expansion valve 18 is set to the second degree, which is larger than the first degree. As a result, the pressure in the high pressure port (fifth port K) of the second flow switch valve 21a is increased, and a pressure difference greater than or equal to the minimum operating differential pressure between the high pressure port of the second flow switch valve 21a and the low pressure port (sixth port I) is guaranteed. the second flow switching valve 21a.

[0079] As noted above, according to the 1st embodiment, when the heating mode is switched to the simultaneous heating-defrosting mode, the minimum operating differential pressure of the second flow switching valve 21a can be guaranteed by performing the differential pressure guarantee process. Therefore, the second flow switching valve 21a can operate normally under any condition.

[0080]

2nd Embodiment

The 2nd embodiment will be described below. The 2nd Embodiment differs from the 1st Embodiment in that the differential pressure guarantee process is carried out when switching from the first operation to the second operation in the simultaneous heating-defrosting mode. The other configuration and control carried out in the refrigeration cycle apparatus 1 is the same as in the 1st embodiment.

[0081] FIG. 12 is a table showing an example of the relationship between the pressure in the second flow switching valve 21a and the outside air temperature in the 2nd embodiment. The table in FIG. 12 shows the pressures in the second flow switch valve 21a during the first operation in the simultaneous heating-defrosting mode when the bypass expansion valve 18 is closed. The minimum operating differential pressure of the second flow switching valve 21a is 0.20 MPa. The suction pressure is the pressure corresponding to the suction saturation temperature obtained by subtracting the temperature difference between the outdoor air temperature and the heat exchanger temperature from the outdoor air temperature, and corresponds to the pressure of the refrigerant at the low pressure port (sixth port I) of the second flow switch valve 21a. It is noted that the temperature of the heat exchanger according to the 2nd embodiment is the temperature of the second outdoor heat exchanger 15b measured by the heat exchanger temperature sensor 92b. The bypass limit pressure is obtained by adding the minimum operating differential pressure to the suction pressure, and is the pressure at the high pressure port required to actuate the second flow switching valve 21a.

[0082] The bypass pressure is the pressure in the high pressure port (fifth port I) of the second flow switch valve 21a, and is the pressure in the first outdoor heat exchanger 15a in the 2nd embodiment. In the 2nd embodiment, the first outdoor heat exchanger 15a operates in the defrosting mode, and thus in the first heat exchanger, the saturation temperature of the refrigerant is in the range of 0°C to 5°C, and the pressure of the refrigerant is in the range of 0.813 MPa to 0.951 MPa. In the example shown in Fig. 12, the bypass pressure is set to 0.813 MPa (saturated temperature=0°C). The deviation corresponds to the values obtained by subtracting the bypass pressure from the bypass limit pressure. In other words, the deviation is the difference between the high pressure orifice pressure necessary to guarantee the minimum operating differential pressure of the second flow switching valve 21a and the actual pressure at the high pressure orifice. If the deviation is negative, then the minimum operating differential pressure can be guaranteed. If the deviation is positive, then the minimum working differential pressure cannot be guaranteed.

[0083] As shown in FIG. 12, in the 2nd embodiment, it is obvious that the higher the outdoor temperature, the larger the deviation. Specifically, when the outside air temperature becomes higher than 1.45°C, the deviation is positive and the minimum operating differential pressure cannot be guaranteed. It is noted that if the bypass pressure is set to 0.951 MPa (saturated temperature=5°C), even when the outdoor temperature is 7°C, the deviation is negative (0.938 MPa - 0.951 MPa = -0.013 MPa), and the minimum operating differential pressure can be guaranteed. Thus, by setting the bypass pressure to 0.951 MPa or lower, the second flow changeover valve 21a and the third flow changeover valve 21b reliably operate at an outside air temperature at which frost is formed. Thus, the following will be described using a pressure of 0.813 MPa as the bypass pressure.

[0084] FIG. 13 is a table showing an example of the relationship between the pressure in the second flow switching valve 21a and the operation frequency of the compressor 11 in the 2nd embodiment. The table in FIG. 13 shows the pressures in the second flow switch valve 21a during the first operation in the simultaneous heating-defrosting mode when the bypass expansion valve 18 is closed. The minimum operating differential pressure of the second flow switching valve 21a is 0.20 MPa. As in the 1st embodiment, it is assumed that the temperature difference between the outdoor air temperature and the temperature of the heat exchanger represents the operating frequency of the compressor 11. It is noted that the temperature of the heat exchanger according to the 2nd embodiment is the temperature of the second outdoor heat exchanger 15b, measured by the heat exchanger temperature sensor 92b. The suction pressure is the pressure corresponding to the suction saturation temperature obtained by subtracting the temperature difference between the outdoor air temperature and the heat exchanger temperature from the outdoor air temperature, and corresponds to the pressure of the refrigerant at the low pressure port (sixth port I) of the second flow switch valve 21a. The bypass limit pressure is obtained by adding the minimum operating differential pressure to the suction pressure, and is the pressure at the high pressure port required to actuate the second flow switching valve 21a. The bypass pressure is the pressure at the high pressure port (fifth port K) of the second flow switch valve 21a, and is the pressure at the first outdoor heat exchanger 15a in the 2nd embodiment. In the example shown in Fig. 12, the bypass pressure is set to 0.813 MPa (saturated temperature=0°C). The deviation corresponds to the values obtained by subtracting the bypass pressure from the bypass limit pressure. In other words, the deviation is the difference between the high pressure orifice pressure required to guarantee the minimum operating differential pressure of the second flow switching valve 21a and the actual pressure at the high pressure orifice. If the deviation is negative, then the minimum operating differential pressure can be guaranteed. If the deviation is positive, then the minimum working differential pressure cannot be guaranteed.

[0085] As shown in FIG. 13, it is clear that the smaller the temperature difference between the outside air temperature and the heat exchanger temperature, that is, the smaller the frequency of the compressor 11, the larger the deviation. Specifically, if the outdoor air temperature is 5°C and the temperature difference is 15°C, then the deviation is -0.03 MPa, and the minimum operating differential pressure can be secured. On the other hand, if the temperature difference is 10°C, then the deviation is 0.078, and it is impossible to ensure the minimum operating differential pressure. That is, if the outdoor air temperature is 5°C and the temperature difference is 10°C, compared with the case where the temperature difference is 15°C, then if the pressure of the high pressure port is not increased, then the minimum operating differential pressure of the second switching valve 21a is ensured. flow is not possible.

[0086] Based on the above, if the outdoor air temperature is high or if the temperature difference between the outdoor air temperature and the heat exchanger temperature is small, that is, if the operating frequency of the compressor 11 is low, then there may be a case where the minimum operating differential pressure cannot be achieved. In the 2nd embodiment, the case where the outdoor air temperature is high or the case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is small, that is, the case where the operation frequency of the compressor 11 is low, is considered as the first condition. If the first condition is met, the opening degree of the bypass expansion valve 18 is controlled so as to increase the pressure of the high pressure port.

[0087] Fig. 14 is a flowchart showing the flow of the simultaneous heating-defrosting mode of the 2nd embodiment. This process is carried out by the operation control unit 501, the condition determination unit 502, and the differential pressure assurance unit 503 of the controller 50. In the 2nd embodiment, steps S205 to S209 shown in FIG. 14 correspond to the differential pressure assurance process. In the heating-defrosting mode, the first operation is carried out first. Specifically, by means of the operating unit 501, the second flow switching valve 21a is switched to the second position (S201). In this case, the third flow switching valve 21b is maintained in the first position, as in the case of the heating mode. According to the result of the differential pressure guarantee process, the bypass expansion valve 18 is set to the first degree or second degree open position, and the defrosting of the first outdoor heat exchanger 15a is started (S202). It is then determined whether a predetermined time has elapsed from the start of the defrosting of the first outdoor heat exchanger 15a (S203). Said predetermined time is the estimated time to complete the defrosting of the first heat exchanger 15a, and an arbitrarily predetermined time is set. If the predetermined time has elapsed (S203: YES), the process proceeds to the processing in S204. On the other hand, if the predetermined time has not elapsed (S203: NO), the processing in S203 is periodically repeated.

[0088] In step S204, the condition determination unit 502 determines whether or not the temperature of the first outdoor heat exchanger 15a measured by the heat exchanger temperature sensor 92a is higher than 5°C (S204). If the temperature of the first outdoor heat exchanger 15a is higher than 5°C (S204: YES), the process proceeds to the processing in step S208. If the temperature of the first outdoor heat exchanger 15a is higher than 5°C, the bypass pressure is 0.951 MPa, and the minimum operating differential pressure can be guaranteed even when the outdoor air temperature is 7°C. Thus, if the temperature of the first outdoor heat exchanger 15a is higher than 5°C, the differential pressure guarantee process is not carried out, and the process proceeds to the processing in step S208.

[0089] On the other hand, if the temperature of the first outdoor heat exchanger 15a is less than or equal to 5°C (S204: YES), the process proceeds to the processing in step S205. In step S205, the outside air temperature is determined by the outside air temperature sensor 91 (S205). Then, a temperature difference between the outside air temperature and the heat exchanger temperature is calculated (S206). Specifically, the temperature difference between the outdoor air temperature and the temperature of the second outdoor heat exchanger 15b measured by the heat exchanger temperature sensor 92b is calculated.

[0090] Then, the condition determination block 502 determines whether the first condition is met (S207). The first condition corresponds, for example, to the case where the outdoor air temperature is greater than or equal to the third limit value and the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value. The third limit value and the fourth limit value are set in advance and stored in the memory of the controller 50. For example, the third limit value is 1.45°C. The fourth limit value is, for example, 15.6°C. As shown in Fig. 13, if the outside air temperature is 7°C and the temperature difference is greater than 15.6°C, then the deviation is negative. As a result, even if the outdoor air temperature is greater than or equal to 1.45° when the temperature difference is greater than 15.6°C, the minimum operating differential pressure can be guaranteed. Thus, considering as the first condition the case where the outdoor air temperature is greater than or equal to the third limit value and the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value, the differential pressure guarantee process control can be prevented unnecessarily if differential pressure assurance process is optional.

[0091] It is noted that the first condition is not limited to the above. For example, the first condition may only correspond to the case where the outdoor air temperature is greater than or equal to the third limit value. Alternatively, the first condition may only correspond to the case where the temperature difference between the outside air temperature and the heat exchanger temperature is less than or equal to the fourth limit value. In addition, the first condition may correspond to the case when the outdoor air temperature is greater than or equal to the third limit value, or when the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value. In addition, when the first condition includes a case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value, a plurality of fourth limit values can be set in accordance with the outdoor air temperature. For example, in the example shown in FIG. 13, if the outdoor temperature is 7°C, then the fourth limit value may be 15.6°C, and if the outdoor temperature is 5°C, then the fourth limit value may be 13.6°C. Any of the mentioned fourth limit values can be selected according to the outdoor temperature. The third limit value and the fourth limit value are appropriately set according to the minimum operating differential pressure of the second flow switch valve 21a and the specifications and operating conditions of the refrigeration cycle apparatus 1, and are not limited to the above-described examples.

[0092] If the first condition is not met (S207: NO), then the opening degree of the bypass expansion valve 18 is set to the predetermined first degree (S208). On the other hand, if the first condition is met (S207:YES), the opening degree of the bypass expansion valve 18 is set to the second degree, which is larger than the first degree, by the differential pressure assurance unit 503 (S209). For example, the second power is 1.5 times larger than the first power. As a result, the differential pressure guarantee process is completed, and the second operation of the simultaneous heating-defrosting mode is performed. Specifically, the second flow switch valve 21a switches to the first position, and the third flow switch valve 21b switches to the second position (S210). The bypass expansion valve 18 is set to the first degree or second degree open position, and the defrosting of the second outdoor heat exchanger 15b is started (S211). Here, in cases where the first condition is met, that is, in cases where the minimum operating differential pressure of the second flow switching valve 21a is not guaranteed, the opening degree of the bypass expansion valve 18 is set to the second degree which is larger than the first degree. As a result, the pressure in the high pressure port (fifth port K) of the second flow switch valve 21a is increased, and a pressure difference greater than or equal to the minimum operating differential pressure between the high pressure port of the second flow switch valve 21a and the low pressure port (sixth port I) is guaranteed. the second flow switching valve 21a. It is noted that, just as in the case of the second flow switching valve 21a, by performing the differential pressure guarantee process, the minimum operating differential pressure of the third flow switching valve 21b can be guaranteed.

[0093] As described above, in the 2nd embodiment, when the first operation of the simultaneous heating-defrost mode is switched to the second operation of the simultaneous heating-defrost mode, the minimum operating differential pressure of the second flow switching valve 21a and the third flow switching valve 21b can be guaranteed. through the implementation of the differential pressure guarantee process. Therefore, the second flow switch valve 21a and the third flow switch valve 21b can operate normally under any condition.

[0094]

3rd Embodiment

The 3rd embodiment will be described below. The 3rd embodiment differs from the 1st embodiment in that the bypass expansion valve 18 includes a flow path to ensure a minimum operating differential pressure. Another configuration of the refrigeration cycle apparatus 1 is the same as that of the 1st embodiment.

[0095] FIG. 15 is a schematic drawing of a bypass expansion valve 18 of the refrigeration cycle apparatus 1 according to the 3rd embodiment. The bypass expansion valve 18 is an electronic expansion valve whose opening degree is controlled by the controller 50. As shown in FIG. 183 which drives the needle 182.

[0096] The main body 180 is formed, for example, by milling and processing a brass casting. In the main body 180, a valve chamber 184 is formed into which the refrigerant flows. A refrigerant inlet 185 is formed in the side surface of the main body 180 to allow refrigerant to flow into the valve chamber 184. A portion of the first high pressure pipe 67 on the bifurcation side 63 (FIG. 1) is connected to the refrigerant inlet 185.

[0097] The seat 181 is positioned so that it passes through the lower part of the main body 180. The seat 181 is tubular, and a refrigerant outlet 186 is formed in the center of the seat 181, which passes through the seat 181 in the axial direction of the seat 181. Part of the first tube 67 of the high side junction 65 (FIG. 1) is connected to the refrigerant outlet 186, and refrigerant whose pressure is reduced flows out of the refrigerant outlet 186. At the seat at the upstream end of the refrigerant outlet 186, a beveled portion 181a is formed that expands upward.

[0098] The needle 182 includes a tip 182a having a conical shape and located in the valve chamber 184. The needle 182 is located so that the tip 182a faces the refrigerant outlet 186 formed in the seat 181, and is movable towards the seat 181 and into direction away from the seat 181. The tip 182a of the needle 182 is shaped to match the beveled portion 181a of the seat 181, and the coolant outlet 186 is blocked by inserting the tip 182a of the needle 182 into the beveled portion 181a of the seat 181. By moving the needle 182 to change the distance to the seat 181, the outlet can be changed. 186 refrigerant and refrigerant outflow rate. That is, the seat 181 and the needle 182 form the restrictive portion of the bypass expansion valve 18.

[0099] A drive device 183 is provided at the top of the main body 180. The drive device 183 includes, for example, a stepper motor or an electromagnetic coil, and causes the needle 182 to reciprocate towards the seat 181 and away from the seat 181 in accordance with a control signal from the controller fifty.

[0100] FIG. 16 is a plan view of the seat 181 of the bypass expansion valve 18 according to the 3rd embodiment. 17 is a sectional view of a restriction portion of the bypass expansion valve 18 according to the 3rd embodiment. Fig. 18 is an enlarged view of a portion of the seat 181 and the needle 182 placed in the restrictive portion, and is a sectional view along the line A-A according to Fig. 16 . As shown in FIGS. 16 and 17, according to the 3rd embodiment, recesses 187 are formed in the restriction portion of the seat 181. Each recess 187 is formed by cutting a portion of the restriction section 181a from the upper end to the lower end of the restriction section 181a. In the 3rd embodiment, the four notches 187 are equally spaced in the circumferential direction.

[0101] FIG. 18 is a sectional view of a restrictive portion in the case where the bypass expansion valve 18 according to the 3rd embodiment is in the closed position. The case when the bypass expansion valve 18 is in the closed position corresponds to the situation when the tip 182a of the needle 182 is adjacent to the restrictive portion 181a of the seat 181. In the current technology, when the bypass expansion valve 18 is in the closed position, the gap between the seat and the needle is not provided, and the coolant does not pass to the coolant outlet 186. In contrast, in the 3rd embodiment, the restrictive portion 181a of the seat 181 contains recesses 187, and therefore, even when the bypass expansion valve 18 is in the closed position, flow paths are formed between the seat 181 and the needle 182, shown in Fig. 18 by dotted lines. . As a result, even if the bypass expansion valve 18 is in the closed position, the refrigerant inside the valve chamber 184 may flow out of the refrigerant outlet 186. Therefore, the predetermined amount of high pressure refrigerant can always move to the fifth port K of the second flow switch valve 21a and the fifth port O of the third flow switch valve 21b through the first high pressure pipe 67 connected to the refrigerant outlet 186.

[0102] As a result, the fifth port K of the second flow switch valve 21a and the fifth port O of the third flow switch valve 21b can be maintained at a high pressure, so that the minimum operating differential pressure between the fifth port K and the sixth port I, which is a port, can be guaranteed. low pressure, and a minimum operating differential pressure between the fifth port O and the sixth port M, which is a low pressure port, can be guaranteed. Thus, the second flow switch valve 21a and the third flow switch valve 21b can operate normally under any condition.

[0103] For example, even if the bypass expansion valve 18 is set to the open position and then forced to move to the closed position due to the failure of the bypass expansion valve 18 in simultaneous heating-defrosting operation, the predetermined amount of high pressure refrigerant is transferred to the second switching valve 21a and the third flow switching valve 21b through the recesses 187. As a result, the minimum operating differential pressure of the second flow switching valve 21a and the third flow switching valve 21b can be ensured, which allows the switching of the second flow switching valve 21a and the third flow switching valve 21b when necessary. .

[0104] Even if the bypass expansion valve 18 is fixed in the closed position due to its failure when switching from the heating mode to the simultaneous heating-defrosting mode, the predetermined amount of high pressure refrigerant is transferred to the second flow switching valve 21a and the third flow switching valve 21b through the recesses 187. As a result, the minimum operating differential pressure of the second flow switching valve 21a and the third flow switching valve 21b, which allows switching of the second flow switching valve 21a and the third flow switching valve 21b, can be guaranteed. Further, since the bypass expansion valve 18 remains in the closed position even after the switching of the second flow switching valve 21a and the third flow switching valve 21b, the flow rate control cannot be carried out in the simultaneous heating-defrosting mode, so that a malfunction is detected. In this case, the switching of the second flow switching valve 21a and the third flow switching valve 21b is performed normally, and therefore it is easy to ascertain that a fault has occurred in the bypass expansion valve 18.

[0105] It is noted that in the 3rd embodiment, the differential pressure guarantee process in the 1st or 2nd embodiment may or may not be performed. In addition, the flow paths in the bypass expansion valve 18 to ensure the minimum operating differential pressure are not limited to the paths formed by the recesses 187. A modification of the 3rd embodiment will be described below.

[0106] FIG. 19 is a sectional view of a restriction portion of the bypass expansion valve 18 according to the modification of the 3rd embodiment. As shown in FIG. 19, the notch 187A may be formed not on the seat 181 but on the tip 182a of the needle 182. Notch 187A is a notch formed by cutting a portion of the tip 182a from the upper end to the lower end of the tip 182a. And in this modification, even if the bypass expansion valve 18 is in the closed position, a flow path is formed between the seat 181 and the needle 182 through which the refrigerant flows. As a result, even if the bypass expansion valve 18 is in the closed position, the predetermined amount of high pressure refrigerant can move to the second flow switch valve 21a and the third flow switch valve 21b, and the minimum operating differential pressure can be guaranteed.

[0107] FIG. 20 is a sectional view of a restrictive portion of the bypass expansion valve 18 according to another modification of the 3rd embodiment. As shown in Fig.20, instead of the recesses 187 on the beveled portion 181A of the seat 181 may be provided with protrusions 188. The tip 182A of the needle 182 may be provided with protrusions 188A. The protrusions 188 and the protrusions 188A are spaced from each other in the circumferential direction so that the coolant flows. It is noted that in FIG. 20 the seat 181 is provided with ridges 188 and the needle 182 is provided with ridges 188A. However, it will suffice that at least one of the seat 181 and the needle 182 contains the corresponding protrusions.

[0108] If projections 188 or projections 188A are provided, then the position in which the seat 181 or needle 182 abuts the projections 188A or projections 188 corresponds to the position in which the bypass expansion valve 18 is closed. In this case, gaps are also formed between seat 181 and needle 182, and said gaps become flow paths, and the coolant moves along said flow paths. As a result, even if the bypass expansion valve 18 is in the closed position, a predetermined amount of high pressure refrigerant can flow into the second flow changeover valve 21a, and the minimum operating differential pressure can be guaranteed. It is noted that the protrusions 188 or protrusions 188A may be integral with the seat 181 or needle 182, or another element such as a spacer may be placed on the beveled portion 181a of the seat 181 or on the tip 182a of the needle 182 and be considered as the protrusions 188 or projections 188A.

[0109] Considering the bypass expansion valve 18 according to the 3rd embodiment, the notches 187 and 187A and the protrusions 188 and 188A can be of any size, and the number of notches 187 and 187A and the protrusions 188 and 188A can be any, as long as a minimum is guaranteed. working differential pressure (for example, from 0.1 MPa to 0.2 MPa), and these sizes and quantities are not limited to the examples shown in Fig.16-20. For example, it is sufficient that the number of recesses 187 and 187A and the number of projections 188 and 188A be greater than or equal to one. It is noted that if the number of recesses 187 and 187A and the number of projections 188 and 188A are too large, or if the dimensions of the recesses 187 and 187A and the dimensions of the projections 188 and 188A are too large, then it is impossible to control the bypass expansion valve 18 according to the required Cv value.

[0110] FIG. 21 is a graph showing the relationship between the opening degree and the capacity Cv for the bypass expansion valve 18. As shown in FIG. 21, if the opening degree of the bypass expansion valve 18 is small, the capacity Cv remains constant. That is, if the opening degree of the bypass expansion valve 18 is small, it is impossible to adjust the capacity Cv. Meanwhile, if the bypass expansion valve 18 is provided with recesses 187 and 187A and projections 188 and 188A, and flow paths are formed, the range in which Cv cannot be adjusted becomes wider, as shown by the dotted line in FIG. Thus, the dimensions and number of recesses 187 and 187A and projections 188 and 188A are chosen to be in a range where minimum operating differential pressures can be guaranteed and Cv can be controlled.

[0111] The configuration of the bypass expansion valve 18 is not limited to the configuration shown in FIG. 15, and, for example, the shapes of the main body 180, the seat 181, and the needle 182, and the positions of the refrigerant inlet 185 and the refrigerant outlet 186 can be measured.

[0112] Embodiments are described above. The present invention is not limited to the above-described embodiments, and can be modified in many ways without departing from the gist of the present invention. For example, the refrigeration cycle apparatus 1 may perform either the above-described differential pressure assurance process of the 1st embodiment or the above-described differential pressure assurance process of the 2nd embodiment, or may perform both of the differential pressure assurance processes. In addition, the second flow switch valve 21a and the third flow switch valve 21b are not limited to four-way valves and may be other valves or valve combinations such as differential pressure controlled three-way valves.

[0113] In the differential pressure assurance processes according to the above-described embodiments, the temperature difference between the outdoor air temperature and the heat exchanger temperature is used as an indicator of the operating frequency of the compressor 11; however, the use of this temperature difference is not mandatory. For example, the operating frequency of the compressor 11 is measured, and the case where the operating frequency of the compressor 11 is less than or equal to the fifth limit value instead of the aforementioned temperature difference can be considered as the first condition. The fifth limit value is set in advance, for example, based on the minimum operating differential pressures, the specifications of the compressor 11 and the conditions of use of the refrigeration cycle device 1, and is stored in the memory of the controller 50.

[0114] In the above-described embodiments, configurations are used in which the pressures in the high-pressure orifices are increased by adjusting the opening degree of the bypass expansion valve 18 to be equal to a second degree that is larger than said predetermined first degree if the first condition is met; however, what is done with these configurations is not limited to this. Instead of or in addition to changing the opening degree of the bypass expansion valve 18, the operating frequency of the compressor 11 may be changed. the frequency of the compressor 11 is set to the predetermined first frequency. If the first condition is met, then the operating frequency of the compressor 11 is set to the second frequency, which is higher than the first frequency. Even in this case, the pressure in the high pressure port (fifth port K) of the second flow switch valve 21a increases, and a pressure difference greater than or equal to the minimum operating differential pressure can be guaranteed between the high pressure port of the second flow switch valve 21a and the low pressure port ( the sixth hole I) of the second flow switch valve 21a.

[0115] In addition, in the above-described embodiments or modifications, if the first condition is met, the opening degree of the bypass expansion valve 18 is permanently set to the second degree; however, the opening degree is not limited to this. For example, if said first condition corresponds to the case where the outdoor air temperature is less than or equal to the first limit value, then the opening degree of the bypass expansion valve 18 can be set in accordance with the outdoor air temperature. Specifically, if the first limit value is set to 0°, then the opening degree of the bypass expansion valve 18 can be set to the second degree when the outdoor air temperature is in the range of 0° to 15°C, and the opening degree of the bypass expansion valve 18 can be set equal to the third degree of opening, which is greater than said second degree of opening, when the outside air temperature is in the range from -5°C to -10°C. Alternatively, a table or equation in which the relationship between the outdoor temperature and the opening degree of the bypass expansion valve 18 is determined is stored in a memory or the like, and the opening degree of the bypass expansion valve 18 can be determined using said table or equation. Even if the first condition is consistent with other examples, the opening degree of the bypass expansion valve 18 can be determined in a similar manner. Even if the operation frequency of the compressor 11 changes instead of the opening degree of the bypass expansion valve 18, the operation frequency of the compressor 11 is not necessarily set to the second frequency permanently, and may be set according to the outdoor temperature, for example.

List of reference positions

[0116]

1 refrigeration cycle device 10 refrigerant circuit 11 compressor 11a suction port 11b outlet port 12 first flow switch valve 13 indoor heat exchanger 14 expansion valve 15a first outdoor heat exchanger 15b - second outdoor heat exchanger, 17a - capillary tube, 17b - capillary tube, 18 - bypass expansion valve, 21a - second flow switch valve, 21b - third flow switch valve, 22 - check valve, 50 - controller, 61 - outlet pipe, 62 - suction pipe; ,82,82a,82b,83a,83b - refrigerant pipe, 91 - outdoor temperature sensor, 92a,92b - heat exchanger temperature sensor, 100 - valve body, 101 - cylinder, 102 - spool mirror, 103 - spool valve, 104,105 - piston, 106 - first cavity, 107 - second cavity, 110,111,112,113 - auxiliary pipe, 120 - auxiliary solenoid valve, 180 - main body, 181 - seat, 181a - beveled part, 182 - needle, 182a - tip, 183 - drive device, 184 - valve chamber, 185 - refrigerant inlet, 186 - refrigerant outlet, 187.187A - notch, 188.188A - ledge, 501 - operational control unit, 502 - condition determination unit, 503 - differential pressure guarantee unit, 504 - memory unit.

Claims (68)

1. Device for the implementation of the refrigeration cycle, containing: a first flow switching valve (12) including a first port (G), a second port (E), a third port (F), and a fourth port (H); a second flow switching valve (21a) and a third flow switching valve (21b), each including a fifth port (K, O), a sixth port (I, M) and a seventh port (L, P), wherein the second valve (21a) the flow switching and the third flow switching valve (21b) are driven by differential pressure; a compressor (11) including a suction port (11a) configured to suck in a refrigerant and an outlet port (11b) configured to discharge the refrigerant; an outlet pipe (61) providing a connection between the outlet (11b) and the first hole (G); a suction pipe (62) providing a connection between the suction port (11a) and the second port (E); a first high pressure pipe (67) providing a connection between the outlet pipe (61) and each of the fifth opening (K) of the second flow switching valve (21a) and the fifth opening (O) of the third flow switching valve (21b); a second high pressure pipe (64) providing a connection between the third opening (F) and a branch (65) located in the first high pressure pipe (67); a bypass expansion valve (18) provided in the section of the first high pressure pipe (67), said section extending between the outlet pipe (61) and the branch (65); a valve (22) located in the second high pressure pipe (64); a low pressure pipe (70) providing a connection between the suction pipe (62) and each of the sixth opening (I) of the second flow switching valve (21a) and the sixth opening (M) of the third flow switching valve (21b); a first outdoor heat exchanger (15a) connected to a seventh port (L) of a second flow switching valve (21a); a second outdoor heat exchanger (15b) connected to a seventh port (P) of a third flow switching valve (21b); an internal heat exchanger (13) connected to the fourth hole (H); and a controller (50) configured to control the operating frequency of the compressor (11) and the degree of opening of the bypass expansion valve (18), moreover, the controller (50) is configured to perform a differential pressure guarantee process when switching the second flow switching valve (21a) or the third flow switching valve (21b), moreover, in the process of guaranteeing the differential pressure, the controller (50) is configured to set the operating frequency of the compressor (11) to the first frequency and set the opening degree of the bypass expansion valve (18) to the first degree if the first condition is not met, and set the operating frequency of the compressor (11) to a second frequency that is higher than the first frequency, or set the opening degree of the bypass expansion valve (18) to a second degree that is greater than the first degree, if the first condition is met. 2. The device for implementing the refrigeration cycle according to claim 1, further comprising: an outside air temperature sensor (91) configured to measure the outside air temperature; and two heat exchanger temperature sensors (92a, 92b) configured to measure the temperature of the first outdoor heat exchanger (15a) and the temperature of the second outdoor heat exchanger (15b), respectively, and the first condition includes at least any of the case when the outdoor air temperature is less than or equal to the first limit value, the case when the temperature difference between the outdoor air temperature and the temperature of the heat exchanger is less than or equal to the second limit value, the case when the outdoor air temperature is greater than or equal to the third limit value, the case where the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value, and the case when the compressor (11) operating frequency is less than or equal to the fifth limit value, wherein the heat exchanger temperature is the temperature of the first outdoor heat exchanger (15a), the temperature of the second outdoor heat exchanger (15b), or the average of the temperature of the first outdoor heat exchanger (15a) and the temperature of the second outdoor heat exchanger (15b). 3. The device for implementing the refrigeration cycle according to claim 2, in which controller (50) is configured to operate in heating mode, in which the first outdoor heat exchanger (15a) and the second outdoor heat exchanger (15b) act as an evaporator, and the indoor heat exchanger (13) acts as a condenser, and in the simultaneous heating-defrosting mode, in which either the first outdoor heat exchanger (15a) or the second outdoor heat exchanger (15b) acts as an evaporator, and the other of the first outdoor heat exchanger (15a) and the second outdoor heat exchanger (15b) and the indoor heat exchanger (13 ) act as a capacitor, moreover, the controller (50) performs a differential pressure guarantee process when switching from the heating mode to the simultaneous heating-defrosting mode. 4. The device for the implementation of the refrigeration cycle according to claim 3, in which the controller (50) is configured to determine that the first condition is met if the outdoor air temperature is less than or equal to the first limit value or if the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the second limit value, when switching from heating mode to simultaneous heating-defrosting mode. 5. Device for implementing the refrigeration cycle according to claim 3 or 4, in which the simultaneous heating-defrosting mode includes a first operation in which the second outdoor heat exchanger (15b) acts as an evaporator, and the first outdoor heat exchanger (15a) and the indoor heat exchanger (13) act as a condenser, and a second operation in which the first outdoor the heat exchanger (15a) acts as an evaporator and the second outer heat exchanger (15b) and the inner heat exchanger (13) act as a condenser, wherein the controller (50) is configured to perform a differential pressure guarantee process when switching from the first operation to the second operation. 6. Device for the implementation of the refrigeration cycle according to claim 5, in which the controller (50) is configured to determine that the first condition is met if the outdoor air temperature is greater than or equal to the third limit value and the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value, when switching from the first operation to the second operation. 7. Device for the implementation of the refrigeration cycle according to claim 2, in which the controller (50) is configured to operate in the simultaneous heating-defrosting mode, including the first operation, in which the second outdoor heat exchanger (15b) acts as an evaporator, and the first outdoor heat exchanger (15a) and the indoor heat exchanger (13) act as a condenser, and a second operation, in which the first outdoor the heat exchanger (15a) acts as an evaporator and the second outer heat exchanger (15b) and the inner heat exchanger (13) act as a condenser, wherein the controller (50) is configured to perform a differential pressure guarantee process when switching from the first operation to the second operation. 8. Device for the implementation of the refrigeration cycle according to claim 7, in which the controller (50) is configured to determine that the first condition is met if the outdoor air temperature is greater than or equal to the third limit value and the temperature difference between the outdoor air temperature and the heat exchanger temperature is less than or equal to the fourth limit value, when switching from the first operation to the second operation. 9. Device for the implementation of the refrigeration cycle according to any one of paragraphs. 2-4, wherein the first limit value, the second limit value, the third limit value, the fourth limit value, and the fifth limit value are predetermined based on the minimum operating differential pressure of the second flow switching valve (21a) or the third flow switching valve (21b). 10. Device for the implementation of the refrigeration cycle, containing: a first flow switching valve (12) including a first port (G), a second port (E), a third port (F), and a fourth port (H); a second flow switching valve (21a) and a third flow switching valve (21b), each including a fifth port (K, O), a sixth port (I, M) and a seventh port (L, P), wherein the second valve (21a) the flow switching and the third flow switching valve (21b) are driven by differential pressure; a compressor (11) including a suction port (11a) for sucking in a refrigerant and an outlet (11b) for discharging the refrigerant; an outlet pipe (61) providing a connection between the outlet (11b) and the first hole (G); a suction pipe (62) providing a connection between the suction port (11a) and the second port (E); a first high pressure pipe (67) providing a connection between the outlet pipe (61) and each of the fifth opening (K) of the second flow switching valve (21a) and the fifth opening (O) of the third flow switching valve (21b); a second high pressure pipe (64) connecting the third hole (F) with a branch (65) located in the first high pressure pipe (67); a bypass expansion valve (18) provided in the section of the first high pressure pipe (67), said section extending between the outlet pipe (61) and the branch (65); a valve (22) located in the second high pressure pipe (64); a low pressure pipe (70) providing a connection between the suction pipe (62) and each of the sixth hole (L) of the second flow switch valve (21a) and the sixth hole (P) of the third flow switch valve (21b); a first outdoor heat exchanger (15a) connected to a seventh port (L) of a second flow switching valve (21a); a second outdoor heat exchanger (15b) connected to a seventh port (P) of a third flow switching valve (21b); and internal heat exchanger (13) connected to the fourth hole (H), moreover, the bypass expansion valve (18) contains a flow path allowing the refrigerant to flow through it, even if the bypass expansion valve (18) is in the closed position. 11. The device for implementing the refrigeration cycle according to claim 10, in which bypass expansion valve (18) includes a seat (181) in which the refrigerant outlet is formed, and a needle (182) that moves towards the seat (181) and away from the seat (181) and changes the opening degree of the refrigerant outlet, and a flow path is formed between the needle (182) and the seat (181). 12. The device for the implementation of the refrigeration cycle according to claim 11, in which at least any one of the seat (181) and the needle (182) contains a recess (187) or protrusion (188), with which a flow path is formed. 13. Device for the implementation of the refrigeration cycle according to claim 11 or 12, in which the closed position is a position in which the seat (181) is adjacent to at least part of the needle (182).

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