Refrigeration cycle device

Abstract

A refrigeration cycle device (1001) is provided with a compressor (10), an oil separator (11), a first heat exchanger (13), an expansion valve (14), and a second heat exchanger (15). The compressor (10), the oil separator (11), the first heat exchanger (13), the expansion valve (14), and the second heat exchanger (15) constitute a refrigerant circuit (C1) in which a refrigerant circulates. The refrigeration cycle device (1001) further comprises: an oil return path (RP) for returning the refrigerator oil from the oil separator (11) to the suction part of the compressor (10); a flow rate adjustment mechanism (16) disposed in the oil return path (RP); and an oil amount detection device (17) that detects the amount of refrigerator oil stored in the oil separator (11). The flow rate adjustment mechanism (16) controls the flow rate of the fluid passing through the oil return path (RP) on the basis of the output of the oil amount detection device (17).

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device. Background Art

[0002] There is a situation where most of the large-scale heating and cooling equipment with a refrigerant circuit such as a commercial air conditioner has an oil return path in order to reduce the amount of oil in the refrigerant circuit. An air conditioner having an oil return path is disclosed in Japanese Patent No. 3874980 (Patent Document 1). One end of this oil return path is connected to an oil separator, and the other end is connected to a refrigerant pipe from an evaporator to a compressor.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 3874980 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the structure disclosed in Japanese Patent No. 3874980, when the amount of oil in the oil separator is small, etc., the refrigerant may flow through the oil return path. When the refrigerant flows into the oil return path, the refrigerant that is not helpful for the capacity circulates in the compressor and the oil return path. As a result, there are problems such as an increase in the work of the compressor and a decrease in the coefficient of performance (COP) of the refrigeration cycle device.

[0008] The present disclosure has been completed to describe an embodiment for solving the above problems, and an object thereof is to provide a refrigeration cycle device that can avoid a decrease in COP and appropriately return the refrigeration oil to the compressor.

[0009] Means for Solving the Problems

[0010] The present disclosure relates to a refrigeration cycle device. The refrigeration cycle device has a compressor, an oil separator, a first heat exchanger, an expansion valve, and a second heat exchanger. The compressor, the oil separator, the first heat exchanger, the expansion valve, and the second heat exchanger constitute a refrigerant circuit for circulating the refrigerant. The refrigeration cycle device further has: an oil return path that returns the refrigeration oil from the oil separator to the suction part of the compressor; a flow rate adjustment mechanism that is disposed in the oil return path; and an oil amount detection device that detects the amount of refrigeration oil stored in the oil separator. The flow rate adjustment mechanism controls the flow rate of the fluid passing through the oil return path according to the output of the oil amount detection device.

[0011] Effects of the Invention

[0012] According to the refrigeration cycle device of the present disclosure, when there is a possibility that the refrigerant is mixed into the oil return path, the flow rate of the fluid passing through the oil return path is reduced, so that the refrigeration oil can be appropriately returned to the compressor while avoiding a decrease in COP. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the configuration of the refrigeration cycle device according to Embodiment 1.

[0014] Figure 2 This is a flowchart for explaining the control of the flow rate adjustment mechanism in the first embodiment.

[0015] Figure 3 This is a diagram showing the configuration of a refrigeration cycle device according to Embodiment 2.

[0016] Figure 4 It is a diagram showing the configuration of a refrigeration cycle device according to Embodiment 3.

[0017] Figure 5 17B is a diagram showing temperature changes when refrigerator oil flows through the oil detection passage 17B.

[0018] Figure 6 It is a diagram showing temperature changes when the refrigerant flows through the oil detection passage 17B.

[0019] Figure 7 It is a diagram showing the configuration of a refrigeration cycle device according to a fourth embodiment.

[0020] Figure 8 This is a diagram showing the configuration of a refrigeration cycle device according to Embodiment 5.

[0021] Figure 9 This is a diagram showing the configuration of a refrigeration cycle device according to a sixth embodiment.

[0022] Figure 10 This is a diagram showing the configuration of a refrigeration cycle device according to a seventh embodiment.

[0023] Figure 11 This is a flowchart for explaining the control of the flow rate regulating mechanism in the eighth embodiment. DETAILED DESCRIPTION

[0024] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, a plurality of embodiments will be described, but the application originally predetermines that the structures described in the various embodiments will be appropriately combined. In addition, in the drawings, the same or equivalent parts are marked with the same reference numerals and their descriptions will not be repeated.

[0025] Implementation Method 1

[0026] Figure 1This is a diagram showing the structure of the refrigeration cycle device according to Embodiment 1. The refrigeration cycle device 1001 includes a compressor 10, an oil separator 11, a heat exchanger 13, an expansion valve 14, a heat exchanger 15, and a control device 600. The compressor 10, the oil separator 11, the heat exchanger 13, the expansion valve 14, and the heat exchanger 15 form a refrigerant circuit C1 through which the refrigerant circulates. During the cooling operation, the heat exchanger 13 functions as a condenser, and the heat exchanger 15 functions as an evaporator.

[0027] The refrigeration cycle device 1001 further includes: an oil return path RP that returns the refrigeration oil from the oil discharge portion of the oil separator 11 to the suction portion of the compressor 10; a flow rate adjustment mechanism 16 disposed in the oil return path RP; an oil quantity detection device 17 that detects the oil storage quantity of the oil separator 11; and a control device 600 that controls the flow rate adjustment mechanism 16 based on the output of the oil quantity detection device 17. The refrigeration oil returns to the suction portion of the compressor 10 through the oil return path RP. The flow rate adjustment mechanism 16 controls the flow rate of the fluid (refrigeration oil and refrigerant) passing through the oil return path RP according to the instruction of the control device 600.

[0028] Although not shown in the figure, a receiver can also be provided between the heat exchanger 13 and the expansion valve 14. In addition, although not shown in the figure, fans can also be provided in the heat exchanger 13 and the heat exchanger 15 respectively.

[0029] The control device 600 is configured to include a CPU (Central Processing Unit) 601, a memory 602 (ROM (Read Only Memory) and RAM (Random Access Memory)), and an input / output buffer (not shown), etc. The CPU 601 expands and executes the program stored in the ROM in the RAM or the like. The program stored in the ROM is a program that describes the processing steps of the control device 600. The control device 600 controls each device in the refrigeration cycle device according to these programs. Regarding this control, it is not limited to software-based processing, and can also be processed by dedicated hardware (electronic circuits).

[0030] In addition, the control device 600 can also be distributed and configured in the indoor unit and the outdoor unit and connected through communication.

[0031] Figure 2It is a flowchart for explaining the control of the flow rate regulating mechanism in Embodiment 1. In step S1, the control device 600 determines whether the amount of the refrigeration oil in the oil separator 11 has decreased according to the output of the oil amount detection device 17. When there is not enough refrigeration oil in the oil separator 11, the refrigerant may flow through the oil return path RP. Hereinafter, the refrigerant that flows through the oil return path RP and bypasses the heat exchangers 13, expansion valve 14, and heat exchanger 15 of the refrigerant circuit C1 and returns to the compressor 10 is referred to as the bypassed refrigerant.

[0032] When the oil amount has decreased (S1: Yes), the control device 600 controls the flow rate regulating mechanism 16, and in step S2, reduces the flow rate of the fluid flowing through the oil return path RP.

[0033] On the other hand, when the oil amount has not decreased (S1: No), the control device 600 controls the flow rate regulating mechanism 16, and in step S3, increases the flow rate of the fluid flowing through the oil return path RP.

[0034] In this way, by controlling the flow rate regulating mechanism 16 to maintain a certain amount of refrigeration oil in the oil separator 11, the amount of the bypassed refrigerant flowing through the oil return path RP when the oil amount decreases can be reduced. Thereby, it is possible to prevent the refrigerant that is not helpful for the cooling capacity from circulating in the compressor 10 and the oil return path RP, prevent an increase in the workload of the compressor 10, and prevent a decrease in the COP.

[0035] Embodiment 2

[0036] In Embodiment 2, a first specific example of the oil amount detection device 17 described in Embodiment 1 is described. Figure 3 It is a diagram showing the structure of the refrigeration cycle device of Embodiment 2. In Figure 3 the shown refrigeration cycle device 1002, the oil amount detection device 17 has an oil level sensor 17A for detecting the height of the oil level inside the oil separator 11. The structure of other parts of the refrigeration cycle device 1002 is the same as that of Figure 1 the shown refrigeration cycle device 1001, so it will not be described repeatedly. In addition, regarding the control device 600, the illustration is omitted in the following figures.

[0037] As the oil level sensor 17A, for example, a float type sensor, a capacitance sensor, a self-heating sensor, etc. can be used.

[0038] The float type sensor has a mechanism for moving the float floating on the oil level inside the oil separator 11 up and down, and detects the oil level by the position of the float.

[0039] The capacitance sensor has a parallel-plate capacitor. The dielectric constant between the electrodes changes when immersed in oil, and thus the capacitance of the capacitor also changes. By detecting the change in capacitance, it is possible to detect whether the amount of refrigeration oil is more than a determination value.

[0040] The self-heating sensor has a resistance element that generates heat when energized. When the resistance element is immersed in oil, the temperature changes, and thus the resistance value also changes. By detecting the change in resistance value, it is possible to detect whether the amount of refrigeration oil is more than a determination value.

[0041] As described above, by using the oil level sensor as the oil amount detection device and controlling the flow rate adjustment mechanism, it is possible to reduce the amount of bypass refrigerant flowing through the oil return path RP when the oil amount decreases. Thereby, it is possible to prevent the refrigerant that does not contribute to the cooling capacity from circulating in the compressor 10 and the oil return path RP, prevent an increase in the workload of the compressor 10, and prevent a decrease in the COP.

[0042] Embodiment 3

[0043] In Embodiment 3, a second specific example of the oil amount detection device 17 described in Embodiment 1 will be described. Figure 4 is a diagram showing the structure of the refrigeration cycle device of Embodiment 3. In Figure 4 the shown refrigeration cycle device 1003, the oil amount detection device 17 has an oil detection path 17B, a solenoid valve 17C, a cooling device 17D, and a temperature sensor 17E. The structure of other parts of the refrigeration cycle device 1003 is the same as that of Figure 1 the shown refrigeration cycle device 1001, and thus will not be described repeatedly.

[0044] The cooling device 17D has an internal heat exchanger 171. The internal heat exchanger 171 is configured to exchange heat between the low-temperature and low-pressure gaseous refrigerant after passing through the heat exchanger 15 and the fluid (refrigeration oil and / or gaseous refrigerant) passing through the oil detection path 17B.

[0045] An intake port P3 of the oil detection path 17B is provided at a predetermined height of the oil separator 11. The position of the intake port P3 is higher than the position of the oil discharge port P4 of the oil separator 11 and lower than the positions of the gas inlet P1 and the gas discharge port P2.

[0046] The solenoid valve 17C, the internal heat exchanger 171, and the temperature sensor 17E are arranged in sequence in the oil detection path 17B. The oil detection path 17B joins the oil return path at a joining point P5 upstream of the flow rate adjustment mechanism 16.

[0047] Figure 5 is a diagram showing the temperature change when refrigeration oil flows through the oil detection path 17B. Figure 6It is a diagram showing the temperature change when refrigerant flows through the oil detection path 17B.

[0048] As Figure 5 shown, when the oil level is higher than the height of the suction port P3, refrigerating machine oil flows through the oil detection path 17B. When it is cooled by the internal heat exchanger 171, the temperature drops from the temperature T1 to the temperature T2 below the saturated gas temperature. On the other hand, as Figure 6 shown, when the oil level is lower than the height of the suction port P3, refrigerant flows through the oil detection path 17B. Even when it is cooled by the internal heat exchanger 171, the temperature only drops to the saturated gas temperature T3. If the internal heat exchanger 171 is properly designed, the Figure 5 and Figure 6 shown temperature difference can be generated.

[0049] Therefore, when detecting the oil level, the solenoid valve 17C is opened, and the temperature is measured by the temperature sensor 17E. When the temperature measured by the temperature sensor 17E is lower than the saturated gas temperature calculated from the pressure detected by a high-pressure sensor (not shown), it can be detected that the oil level is lower than the height of the suction port P3.

[0050] As described above, as an oil quantity detection device, the oil level position is detected based on the temperature change when the fluid flowing through the oil detection path 17B is cooled. If the flow rate adjustment mechanism is controlled, the amount of bypass refrigerant flowing through the oil return path RP when the oil quantity decreases can be reduced. Thereby, it is possible to prevent the refrigerant that is not helpful for the cooling capacity from circulating in the compressor 10 and the oil return path RP, prevent an increase in the workload of the compressor 10, and prevent a decrease in the COP.

[0051] Embodiment 4

[0052] In Embodiment 4, a third specific example of the oil quantity detection device 17 described in Embodiment 1 will be described. Figure 7 It is a diagram showing the structure of the refrigeration cycle device of Embodiment 4. Figure 7 The refrigeration cycle device 1004 shown in Figure 1 is based on the structure of the refrigeration cycle device 1001 shown in

[0053] and further includes a bypass flow path BP, a heat exchanger 19, and an expansion valve 20.

[0054] The heat exchanger 19 is configured to have a first flow path and a second flow path, and heat exchange is performed between the refrigerants flowing through these flow paths. The refrigerant that has passed through the heat exchanger 13 flows through the first flow path of the heat exchanger 19. The bypass flow path BP branches from the branch point between the outlet portion of the first flow path of the heat exchanger 19 and the expansion valve 14, and converges with the refrigerant circuit C1 near the suction port of the compressor 10.

[0054] In addition, the oil quantity detection device 17 includes an oil detection passage 17B, a solenoid valve 17C, a cooling device 17D, and a temperature sensor 17E. The structures of the other parts of the refrigeration cycle device 1004 are the same as those of Figure 1 the refrigeration cycle device 1001 shown, and thus will not be described repeatedly.

[0055] In Embodiment 4, the cooling device 17D includes an internal heat exchanger 172. The internal heat exchanger 172 is configured to exchange heat between the refrigerant in the bypass passage BP after passing through the heat exchanger 19 and the fluid (refrigeration oil and / or gaseous refrigerant) passing through the oil detection passage 17B.

[0056] An intake port P3 of the oil detection passage 17B is provided at a predetermined height of the oil separator 11. The position of the intake port P3 is higher than the position of the oil discharge port P4 of the oil separator 11 and lower than the positions of the gas inlet port P1 and the gas discharge port P2.

[0057] The solenoid valve 17C, the internal heat exchanger 172, and the temperature sensor 17E are sequentially arranged in the oil detection passage 17B. The oil detection passage 17B joins the oil return path at a joining point P5 upstream of the flow rate adjustment mechanism 16.

[0058] In Embodiment 4, if the internal heat exchanger 172 is designed to generate Figure 5 and Figure 6 the temperature difference shown, the oil level position can also be detected.

[0059] In Embodiment 4, similar to Embodiment 3, an increase in the workload of the compressor 10 can be prevented, and a decrease in the COP can be prevented. Furthermore, since the flow rate of the refrigerant flowing through the bypass passage BP can be controlled by the expansion valve 20, the heat exchange amount of the heat exchanger 172 can be adjusted to an arbitrary value, and even if the state of the refrigeration cycle changes, it can be dealt with in a wide range. Therefore, the design of the heat exchanger 172 becomes easy.

[0060] Embodiment 5

[0061] In Embodiment 5, a first specific example of the flow rate adjustment mechanism described in Embodiment 1 will be described. Figure 8 is a diagram showing the structure of the refrigeration cycle device of Embodiment 5. In Figure 8 the refrigeration cycle device 1005 shown, an electronic expansion valve (Linear Expansion Valve: LEV) 16A is provided as the flow rate adjustment mechanism 16. The structures of the other parts of the refrigeration cycle device 1005 are the same as those of Figure 1 the refrigeration cycle device 1001, and will not be described repeatedly.

[0062] By using the electronic expansion valve 16A, the control device 600 can increase or decrease the flow rate of the fluid (refrigerant and refrigerating oil) passing through the oil return path RP according to the output of the oil quantity detection device 17.

[0063] In Embodiment 5, as the oil quantity detection device 17, any one of the structures shown in Embodiments 2 to 4 can be used. In addition, the control device 600 can control the flow rate using the control shown in Embodiment 1.

[0064] Embodiment 6

[0065] In Embodiment 6, a second specific example of the flow rate adjustment mechanism described in Embodiment 1 will be described. Figure 9 It is a diagram showing the structure of the refrigeration cycle device of Embodiment 6. In Figure 9 In the refrigeration cycle device 1006 shown, the flow rate adjustment mechanism 16 has a solenoid valve 16B and a capillary tube 16C connected in series to the oil return path RP. The structures of the other parts of the refrigeration cycle device 1006 are the same as those of Figure 1 the refrigeration cycle device 1001 and will not be described repeatedly.

[0066] As described above, a capillary tube 16C and a solenoid valve 16B are provided in the oil return path RP. When increasing the flow rate, the solenoid valve 16B is controlled to be open, and when decreasing the flow rate, the solenoid valve 16B is controlled to be closed. Thus, the control device 600 can adjust the flow rate of the refrigerant and the refrigerating oil passing through the oil return path RP.

[0067] In Embodiment 6, as the oil quantity detection device 17, any one of the structures shown in Embodiments 2 to 4 can be used. In addition, the control device 600 can control the flow rate using the control shown in Embodiment 1.

[0068] When a LEV is arranged in the oil return path RP as in Embodiment 5, it is preferable to use a component different from the expansion valve 14. Since high-temperature refrigerating oil and refrigerant discharged from the compressor 10 flow through the oil return path RP, the LEV requires high heat resistance. Therefore, Figure 8 the LEV arranged in the oil return path RP used in

[0069] Embodiment 7

[0070] In Embodiment 7, a third specific example of the flow rate adjustment mechanism described in Embodiment 1 will be described. Figure 10 It is a diagram showing the structure of the refrigeration cycle device of Embodiment 7. InFigure 10 In the refrigeration cycle device 1007 shown, after the oil return path RP branches into a flow path RP1 and a flow path RP2 at a branch point BP1, they converge at a convergence point MP1. The flow rate adjustment mechanism 16 has a solenoid valve 16B and a capillary tube 16C connected in series in the flow path RP1, and a capillary tube 16D arranged in the flow path RP2.

[0071] In Embodiment 7, as the oil quantity detection device 17, any one of the structures shown in Embodiments 2 to 4 can be used. In addition, the control device 600 can perform flow control using the control shown in Embodiment 1.

[0072] As Figure 10 shown, the oil return path RP is branched into RP1 and RP2 in parallel, capillary tubes 16C and 16D are respectively provided, and a solenoid valve 16B is provided in one flow path RP1. By opening the solenoid valve 16B when increasing the flow rate and closing the solenoid valve 16B when decreasing the flow rate, the control device 600 can adjust the flow rate.

[0073] In Figure 9 the structure shown, when the flow rate is decreased, the flow rate becomes zero. However, in Figure 10 the structure shown, even when the flow rate is decreased, a certain amount of refrigeration oil can be returned to the compressor 10.

[0074] Embodiment 8

[0075] In Embodiment 1, during the operation of the refrigeration cycle device, the amount of refrigerant flowing through the oil return path RP is always monitored, and flow control is performed based on the flow rate adjustment mechanism 16. However, the flow rate adjustment mechanism 16 also has a movable part, and in terms of the device life, it is more advantageous to reduce the number of times the movable part moves.

[0076] Therefore, in Embodiment 8, the control shown in Figure 2 is executed under the condition that the refrigerant easily flows into the oil return path RP.

[0077] Figure 11 is a flowchart for explaining the control of the flow rate adjustment mechanism in Embodiment 8. In step S11, the control device 600 determines whether the execution condition for determining whether to execute the flow rate adjustment control is satisfied.

[0078] For example, when the operating frequency of the compressor 10 is lower than the determination frequency, the control device 600 determines that the execution condition in step S11 is satisfied. The determination frequency can be set, for example, to a frequency that is half of the upper limit value of the operating frequency of the compressor.

[0079] When the operating frequency of the compressor 10 is low, the discharge amount of the refrigeration oil from the compressor 10 decreases. The amount of the refrigeration oil in the oil separator 11 becomes less, and thus, the refrigerant is likely to return to the oil return path RP. On the other hand, when there is a large amount of the refrigeration oil in the oil separator 11, the refrigeration oil mainly flows through the oil return path RP, and thus, it is not easy to cause a reduction in the COP due to the existence of the oil return path. Therefore, as described above, the operation frequency of the compressor is used to determine whether to execute the flow rate adjustment control.

[0080] In addition, the execution conditions are not limited thereto. For example, when the pressure difference between the suction part and the discharge part of the compressor 10 is smaller than the determination threshold value, the control device 600 determines that the execution condition of step S11 is satisfied. In this case, the determination threshold value can be set to half of the maximum value of the pressure difference.

[0081] When the diameters of the fluid passage restricting parts of the flow rate adjustment mechanism are the same, the larger the differential pressure is, the more the amount of the fluid flowing through the oil return path RP increases, and thus, the refrigerant is likely to return. Therefore, as described above, it is also possible to determine whether to execute the flow rate adjustment control according to the magnitude of the differential pressure.

[0082] When the execution condition is not satisfied (S11: No), in step S15, the control device 600 fixes the flow rate of the flow rate adjustment mechanism 16 to a standard value. Thereby, the number of times of movement of the movable part of the flow rate adjustment mechanism 16 can be reduced, which is advantageous in terms of the product life.

[0083] When the execution condition is satisfied (S11: Yes), in step S12, the control device 600 determines whether the amount of the refrigeration oil in the oil separator 11 has decreased according to the output of the oil amount detection device 17. When there is not enough refrigeration oil in the oil separator 11, the refrigerant may flow through the oil return path RP.

[0084] When the oil amount has decreased (S12: Yes), the control device 600 controls the flow rate adjustment mechanism 16, and in step S13, reduces the flow rate of the fluid flowing through the oil return path RP.

[0085] On the other hand, when the oil amount has not decreased (S12: No), the control device 600 controls the flow rate adjustment mechanism 16, and in step S14, increases the flow rate of the fluid flowing through the oil return path RP.

[0086] Thus, by controlling the flow rate regulating mechanism 16 to maintain a certain amount of refrigerating machine oil in the oil separator 11, the amount of bypass refrigerant flowing through the oil return path RP when the oil amount decreases can be reduced. As a result, it is possible to prevent the refrigerant that does not contribute to the cooling capacity from circulating in the compressor 10 and the oil return path RP, prevent an increase in the workload of the compressor 10, and prevent a decrease in the COP.

[0087] In Embodiment 8, as the oil amount detection device 17, any one of the structures shown in Embodiments 2 to 4 can be used. In addition, as the flow rate regulating mechanism 16, any one of the structures shown in Embodiments 5 to 7 can be used.

[0088] In Embodiment 8, the same effects as those of Embodiments 1 to 7 can be obtained, and compared with Embodiments 1 to 7, the life of the flow rate regulating mechanism 16 can be extended.

[0089] (Summary)

[0090] Next, the embodiments will be summarized again with reference to the drawings.

[0091] (1) The refrigeration cycle device 1001 shown in Figure 1 has a compressor 10, an oil separator 11, a heat exchanger 13, an expansion valve 14, and a heat exchanger 15. The compressor 10, the oil separator 11, the heat exchanger 13, the expansion valve 14, and the heat exchanger 15 constitute a refrigerant circuit C1 for circulating the refrigerant. The refrigeration cycle device 1001 further has: an oil return path RP that returns the refrigerating machine oil from the oil separator 11 to the suction part of the compressor 10; a flow rate regulating mechanism 16 disposed in the oil return path RP; and an oil amount detection device 17 that detects the amount of refrigerating machine oil stored in the oil separator 11. The flow rate regulating mechanism 16 controls the flow rate of the fluid passing through the oil return path RP according to the output of the oil amount detection device 17.

[0092] (2) In Item 1, as Figure 3 shown, the oil amount detection device 17 has an oil level sensor 17A that detects the position of the oil level in the oil separator.

[0093] (3) In Item 1, as Figure 4 shown, the oil amount detection device 17 has: an oil detection path 17B that is connected to the oil separator 11 at a suction port P3 at a position higher than the position of the oil discharge port P4 where one end of the oil return path RP is connected to the oil separator 11 and is connected to the oil return path RP at a confluence point P5 provided in the oil return path RP; a cooling device 17D that cools the fluid passing through the oil detection path 17B; and a temperature sensor 17E that detects the temperature of a part of the oil detection path 17B after passing through the cooling device 17D.

[0094] (4) In item 3, as Figure 4 shown, the cooling device 17D has a heat exchanger 171 configured to perform heat exchange between the refrigerant flowing from the heat exchanger 15 towards the compressor 10 in the refrigerant circuit C1 and the fluid passing through the oil detection path 17B.

[0095] (5) In item 3, as Figure 7 shown, the refrigeration cycle device 1004 further has a bypass flow path BP that branches a part of the refrigerant flowing from the heat exchanger 13 towards the expansion valve 14 in the refrigerant circuit C1 and returns it to the compressor 10. The cooling device 17D has a heat exchanger 172 configured to perform heat exchange between the refrigerant passing through the bypass flow path BP and the fluid passing through the oil detection path 17B.

[0096] (6) In any one of items 1 to 5, as Figure 8 shown, the flow rate adjustment mechanism 16 has an electronic expansion valve 16A.

[0097] (7) In any one of items 1 to 5, as Figure 9 shown, the flow rate adjustment mechanism 16 has a solenoid valve 16B and a capillary tube 16C connected in series to the oil return path RP.

[0098] (8) In any one of items 1 to 5, as Figure 10 shown, after the oil return path RP branches into a flow path RP1 and a flow path RP2 at the branch point BP1, they converge at the convergence point MP. The flow rate adjustment mechanism 16 has a solenoid valve 16B and a capillary tube 16C connected in series to the flow path RP1, and a capillary tube 16D disposed in the flow path RP2.

[0099] (9) In any one of items 1 to 8, the refrigeration cycle device 1001 further has a control device 600 that controls the compressor 10 and the flow rate adjustment mechanism 16. As Figure 11 shown, the control device 600 is configured to execute a first control (S15) in which the flow rate of the flow rate adjustment mechanism 16 is fixed during the operation of the compressor 10, and a second control (S12 to S14) in which the flow rate of the flow rate adjustment mechanism 16 is controlled according to the output of the oil quantity detection device 17 during the operation of the compressor 10.

[0100] (10) In item 9, as Figure 11 shown, the control device 600 is configured to execute the first control (S15) when the operating frequency of the compressor 10 is higher than the threshold value, and execute the second control (S12 to S14) when the operating frequency is lower than the threshold value.

[0101] (11) In Item 9, as Figure 11 shown, the control device 600 is configured to execute the first control (S15) when the pressure difference between the suction part and the discharge part of the compressor 10 is smaller than the threshold value, and execute the second control (S12 to S14) when the pressure difference is larger than the threshold value.

[0102] It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present disclosure is not shown by the description of the above embodiments, but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0103] Reference Numeral Explanation

[0104] 10: Compressor; 11: Oil separator; 13, 15, 19, 171, 172: Heat exchanger; 14, 20: Expansion valve; 16: Flow rate regulating mechanism; 16A: Electronic expansion valve; 16B, 17C: Solenoid valve; 16C, 16D: Capillary tube; 17: Oil quantity detection device; 17A: Oil level sensor; 17B: Oil detection path; 17D: Cooling device; 17E: Temperature sensor; 600: Control device; 601: CPU; 602: Memory; 1001 to 1007: Refrigeration cycle device; BP: Bypass flow path; BP1: Branch point; C1: Refrigerant circuit; MP, MP1, P5: Confluence point; P1: Gas inlet; P2: Gas outlet; P3: Suction port; P4: Oil discharge port; RP: Oil return path; RP1, RP2: Flow path.

Claims

1. A refrigeration cycle device, wherein, the refrigeration cycle device includes a compressor, an oil separator, a first heat exchanger, an expansion valve, and a second heat exchanger, the compressor, the oil separator, the first heat exchanger, the expansion valve, and the second heat exchanger form a refrigerant circuit for refrigerant circulation, the refrigeration cycle device further includes: an oil return path that returns refrigeration oil from the oil separator to the suction part of the compressor; a flow rate adjustment mechanism disposed in the oil return path; and an oil quantity detection device that detects the quantity of refrigeration oil stored in the oil separator, the flow rate adjustment mechanism controls the flow rate of the fluid passing through the oil return path according to the output of the oil quantity detection device.

2. The refrigeration cycle device according to claim 1, wherein, the oil quantity detection device includes an oil level sensor that detects the position of the oil level in the oil separator.

3. The refrigeration cycle device according to claim 1, wherein, the oil quantity detection device includes: an oil detection path that is connected to the oil separator at a position higher than the position where one end of the oil return path is connected to the oil separator, and is connected to the oil return path at the connection point provided in the oil return path; a cooling device that cools the fluid passing through the oil detection path; and a temperature sensor that detects the temperature of the part of the oil detection path after passing through the cooling device.

4. The refrigeration cycle device according to claim 3, wherein, the cooling device includes a third heat exchanger configured to perform heat exchange between the refrigerant flowing from the second heat exchanger towards the compressor in the refrigerant circuit and the fluid passing through the oil detection path.

5. The refrigeration cycle device according to claim 3, wherein, the refrigeration cycle device further includes a bypass flow path that branches a part of the refrigerant flowing from the first heat exchanger towards the expansion valve in the refrigerant circuit and returns it to the compressor, the cooling device includes a third heat exchanger configured to perform heat exchange between the refrigerant passing through the bypass flow path and the fluid passing through the oil detection path.

6. The refrigeration cycle device according to any one of claims 1 to 5, wherein, the flow rate adjustment mechanism includes an electronic expansion valve.

7. The refrigeration cycle device according to any one of claims 1 to 5, wherein, the flow rate adjustment mechanism includes a solenoid valve and a capillary tube connected in series in the oil return path.

8. The refrigeration cycle device according to any one of claims 1 to 5, wherein, after the oil return path branches into a first flow path and a second flow path at a branch point and then converges at a convergence point, the flow rate adjustment mechanism includes: a solenoid valve and a first capillary tube connected in series in the first flow path; and a second capillary tube disposed in the second flow path.

9. The refrigeration cycle device according to any one of claims 1 to 8, wherein, the refrigeration cycle device further includes a control device that controls the compressor and the flow rate adjustment mechanism, The control device is configured to perform a first control in which the flow rate of the flow rate adjusting mechanism is fixed during the operation of the compressor, and a second control in which the flow rate of the flow rate adjusting mechanism is controlled according to the output of the oil amount detecting device during the operation of the compressor.

10. The refrigeration cycle device according to claim 9, wherein the control device is configured to perform the first control when the operating frequency of the compressor is higher than a threshold value, and perform the second control when the operating frequency is lower than the threshold value.

11. The refrigeration cycle device according to claim 9, wherein the control device is configured to perform the first control when the pressure difference between the suction part and the discharge part of the compressor is smaller than a threshold value, and perform the second control when the pressure difference is larger than the threshold value.

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