COOLING CIRCUIT DEVICE

Abstract

A refrigeration cycle device (1001) comprises 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) form a refrigerant circuit (C1) through which refrigerant circulates. The refrigeration cycle device (1001) further comprises an oil return path (RP) configured to return refrigeration oil from the oil separator (11) to the inlet of the compressor (10), a flow rate adjustment mechanism (16) arranged on the oil return path (RP), and an oil quantity measuring device (17) configured to detect an amount of refrigeration oil stored in the oil separator (11).The flow rate adjusting mechanism (16) operates in response to an output of the oil amount measuring device (17) to regulate a flow rate of a fluid passing through the oil return path (RP).

Description

TECHNICAL FIELD

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

[0002] Many thermal appliances, such as commercial air conditioners, with a large-scale refrigerant cycle may include an oil return path to reduce the amount of oil in the refrigerant cycle. Japanese Patent No. 3874980 (PTL 1) discloses an air conditioner with an oil return path. The oil return path is connected to an oil separator at one end and to a refrigerant line leading from an evaporator to a compressor at the other end. REFERENCE LISTPATENT LITERATURE

[0003] PTL 1: Japanese Patent No. 3874980 SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0004] In the configuration disclosed in Japanese Patent No. 3874980, there is a possibility that refrigerant may flow into the oil return path when the oil separator contains a small amount of oil. When refrigerant flows into the oil return path, the refrigerant, which does not contribute to efficiency, circulates through the compressor and the oil return path. As a result, the compressor's workload increases, and the refrigeration cycle device disadvantageously has a reduced coefficient of performance (COP).

[0005] The present disclosure has been made to describe an embodiment to solve such a problem as explained above, and contemplates a refrigeration cycle device capable of adequately returning refrigerating machine oil to a compressor while avoiding a reduced COP. SOLUTION TO THE PROBLEM

[0006] The present disclosure relates to a refrigeration cycle device. 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 through which the refrigerant circulates. The refrigeration cycle device further includes an oil return path configured to return refrigeration oil from the oil separator to an inlet of the compressor, a flow rate adjustment mechanism disposed on the oil return path, and an oil amount measuring device configured to detect an amount of refrigeration oil stored in the oil separator.The flow rate adjusting mechanism is configured to operate in response to an output of the oil amount measuring device to regulate a flow rate of a fluid passing through the oil return path. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0007] The refrigeration cycle device presented here can reduce a flow rate of a fluid passing through an oil return path when there is a possibility of refrigerant being introduced into the oil return path, and the refrigeration cycle device can thus adequately return refrigeration oil to the compressor while avoiding a reduced COP. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a configuration of a refrigeration cycle device according to a first embodiment. Fig. 2 is a flowchart illustrating how a flow rate adjustment mechanism is controlled according to the first embodiment. Fig. 3 is a diagram showing a configuration of a refrigeration cycle device according to a second embodiment. Fig. 4 is a diagram showing a configuration of a refrigeration cycle device according to a third embodiment. Fig. 5 is a diagram showing how the temperature of the refrigerating oil changes when the refrigerating oil flows through an oil measuring path 17B. Fig. 6 is a diagram showing how the temperature of the refrigerating machine oil changes when the refrigerant flows through the oil measuring path 17B. Fig. 7 is a diagram showing a configuration of a refrigeration cycle device according to a fourth embodiment. Fig. 8 is a diagram showing a configuration of a refrigeration cycle device according to a fifth embodiment. Fig. 9 is a diagram showing a configuration of a refrigeration cycle device according to a sixth embodiment. Fig. 10 is a diagram showing a configuration of a refrigeration cycle device according to a seventh embodiment. Fig. 11 is a flowchart illustrating how a flow rate adjustment mechanism is controlled according to an eighth embodiment. DESCRIPTION OF THE EMBODIMENTS

[0008] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although a variety of embodiments are described below, at the time of filing this application, it was originally intended to adequately combine the configurations described in the embodiments. In the drawings, identical or equivalent components are designated identically and will not be described repeatedly. First embodiment.

[0009] Fig. 1 is a diagram showing a configuration of a refrigeration cycle device according to a first embodiment. A 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 unit 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 refrigerant circulates. In cooling operation, the heat exchanger 13 acts as a condenser, and the heat exchanger 15 acts as an evaporator.

[0010] The refrigeration cycle device 1001 further includes an oil return path RP configured to return refrigerating oil from an oil discharge outlet of the oil separator 11 to an inlet of the compressor 10, a flow rate adjustment mechanism 16 disposed on the oil return path RP, an oil amount measuring device 17 configured to detect an amount of oil stored in the oil separator 11, and a control unit 600 configured to control the flow rate adjustment mechanism 16 in response to an output of the oil amount measuring device 17. The refrigerating oil is returned to the inlet of the compressor 10 via the oil return path RP. The flow rate adjusting mechanism 16 operates in response to a command received from the control unit 600 to control a flow rate of a fluid (refrigerator oil and refrigerant) passing through the oil return path RP.

[0011] Although not shown, a liquid receiver may be provided between the heat exchanger 13 and the expansion valve 14. Furthermore, although not shown, the heat exchangers 13 and 15 are each equipped with a fan.

[0012] The control unit 600 includes a CPU (Central Processing Unit) 601, a memory 602 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown), and the like. The CPU 601 loads a program stored in the ROM into the RAM or the like and executes the program. The program stored in the ROM is a program describing a processing flow for the control unit 600. The control unit 600 controls each device in the refrigeration cycle device according to these programs. This control is not limited to processing by software but can also be processed by dedicated hardware (or electronic circuit).

[0013] It should be noted that the control unit 600 may be distributed between an indoor unit and an outdoor unit and connected by communication.

[0014] Fig. 2 is a flowchart illustrating how the flow rate adjustment mechanism is controlled according to the first embodiment. In step S1, the control unit 600 determines whether the oil separator 11 has a reduced amount of refrigerating oil based on an output of the oil amount measuring device 17. If there is an insufficient amount of refrigerating oil in the oil separator 11, there is a possibility that refrigerant may flow through the oil return path RP. Refrigerant that flows through the oil return path RP, bypasses the heat exchanger 13, the expansion valve 14, and the heat exchanger 15 of the refrigerant circuit C1, and returns to the compressor 10, is hereinafter referred to as bypass refrigerant.

[0015] When the oil separator has a reduced amount of oil (YES in S1), the control unit 600 controls the flow rate adjusting mechanism 16 to reduce a flow rate of a fluid flowing through the oil return path RP in step S2.

[0016] On the other hand, when the oil separator does not have a reduced oil amount (NO in S1), the control unit 600 controls the flow rate adjusting mechanism 16 to increase the flow rate of the liquid flowing through the oil return path RP in step S3.

[0017] In this way, the flow rate adjustment mechanism 16 can be controlled to retain a certain amount of refrigeration oil in the oil separator 11 to reduce the amount of bypass refrigerant flowing through the oil return path RP when the oil separator has a reduced oil amount. This can prevent refrigerant that does not contribute to the cooling capacity from circulating through the compressor 10 and the oil return path RP, thus preventing increased work of the compressor 10 and thus a reduced COP. Second embodiment.

[0018] In a second embodiment, a first concrete example of the oil quantity measuring device 17 explained in the first embodiment is explained. Fig. 3 is a diagram showing a configuration of a refrigeration cycle device according to the second embodiment. In a Fig. 3, the oil quantity measuring device 17 comprises an oil level sensor 17A, which is configured to measure a level of a surface of oil in the oil separator 11. The rest of the refrigeration cycle device 1002 is constructed similarly to the Fig. 1 and will therefore not be described repeatedly. Note that the control unit 600 is not shown in the following figures.

[0019] The oil level sensor 17A may be, for example, a float type sensor, a capacitance sensor, a self-heating sensor, or the like.

[0020] The float-type sensor has a mechanism in which a float floating on the surface of the oil in the oil separator 11 moves up and down, and the float-type sensor measures an oil level depending on the position of the float.

[0021] The capacitance sensor includes a plate capacitor. Since the dielectric constant between the electrodes changes in response to immersion in oil, the capacitor's capacitance also changes. By detecting a change in capacitance, it can be determined whether the refrigeration oil contains a quantity greater than a reference value.

[0022] The self-heating sensor has a resistance element that conducts electricity and generates heat. When the resistance element is immersed in oil, its temperature changes, and thus its resistance value changes. By detecting the change in resistance value, it can be determined whether the refrigeration oil contains a quantity greater than the reference value.

[0023] By using an oil level sensor as the oil quantity measuring device for controlling the flow rate adjustment mechanism, the amount of bypass refrigerant flowing through the oil return path RP can be reduced when the oil separator has a reduced oil quantity. This can prevent refrigerant that does not contribute to the cooling capacity from circulating through the compressor 10 and the oil return path RP, thus preventing increased work of the compressor 10 and thus a reduced COP. Third embodiment

[0024] In a third embodiment, a second concrete example of the oil quantity measuring device 17 explained in the first embodiment will be explained. Fig. 4 is a diagram showing a configuration of a refrigeration cycle device according to the third embodiment. In a Fig. 4, the oil quantity measuring device 17 comprises an oil measuring path 17B, a solenoid valve 17C, a cooling device 17D and a temperature sensor 17E. The rest of the refrigeration cycle device 1003 is constructed similarly to the Fig. 1 and will therefore not be described repeatedly.

[0025] The cooling device 17D includes an internal heat exchanger 171. The internal heat exchanger 171 is configured so that a low-temperature, low-pressure gaseous refrigerant that has passed through the heat exchanger 15 and a fluid (refrigerator oil and / or gaseous refrigerant) that passes through the oil measurement path 17B exchange heat.

[0026] The oil measurement path 17B has a suction inlet P3 that is set to a predetermined level on the oil separator 11. The suction inlet P3 is higher in level than an oil discharge outlet P4 of the oil separator 11 and lower in level than a gas flow inlet P1 and a gas discharge outlet P2.

[0027] The solenoid valve 17C, the internal heat exchanger 17I, and the temperature sensor 17E are arranged in this order along the oil sensing path 17B. The oil sensing path 17B connects to the oil return path at a junction point P5 upstream of the flow rate adjustment mechanism 16.

[0028] Fig. 5 is a diagram showing how the temperature of the refrigerating oil changes when the refrigerating oil flows through the oil measuring path 17B. Fig. 6 is a diagram showing how the temperature of the refrigerating machine oil changes when the refrigerant flows through the oil measuring path 17B.

[0029] As in Fig. As shown in Figure 5, refrigeration oil flows through the oil measurement path 17B when the oil level is higher than the level of the suction inlet P3. When the refrigeration oil is cooled by the internal heat exchanger 171, the temperature of the refrigeration oil drops from a temperature T1 to a temperature T2, which is equal to or lower than the temperature of the saturated gas. In contrast, as shown in Fig. As shown in Figure 6, refrigerant flows through the oil measurement path 17B when the oil level is lower than the level of the suction inlet P3. When the refrigerant is cooled by the indoor heat exchanger 171, the temperature of the refrigerant only drops to the temperature T3 of the saturated gas. If the indoor heat exchanger 171 is adequately designed, the Fig. 5 and Fig. 6 shown temperature difference.

[0030] Accordingly, when the oil level is detected, the solenoid valve 17C opens, and the temperature sensor 17E measures the temperature. If the temperature measured by the temperature sensor 17E is lower than the saturated gas temperature converted from the pressure measured by a high-pressure sensor (not shown), it can be measured that the oil level is lower than the level of the intake inlet P3.

[0031] As described above, if the oil quantity measuring device detects an oil level based on the temperature change of a fluid flowing through the oil measurement path 17B as the fluid is cooled, and the flow rate adjustment mechanism is controlled, the amount of bypass refrigerant flowing through the oil return path RP can be reduced when the oil separator has a reduced oil quantity. This can prevent refrigerant that does not contribute to the cooling capacity from circulating through the compressor 10 and the oil return path RP, thus preventing increased work of the compressor 10 and thus a reduced COP. Fourth embodiment.

[0032] In a fourth embodiment, a third concrete example of the oil quantity measuring device 17 explained in the first embodiment will be described. Fig. 7 is a diagram showing a configuration of a refrigeration cycle device according to the fourth embodiment. Fig. Refrigeration cycle device 1004 shown in Fig. 7 comprises, in addition to the Fig. 1, the refrigeration cycle device 1001 includes a bypass flow path BP, a heat exchanger 19, and an expansion valve 20.

[0033] The heat exchanger 19 has a first and a second flow path and is designed for heat exchange between the refrigerant flowing through the flow paths. The first flow path of the heat exchanger 19 carries refrigerant that has passed through the heat exchanger 13. The bypass flow path BP branches from a branch point between an outlet of the first flow path of the heat exchanger 19 and the expansion valve 14 and flows into the refrigerant circuit C1 near the inlet of the compressor 10.

[0034] The oil quantity measuring device 17 further comprises an oil measuring path 17B, a solenoid valve 17C, a cooling device 17D and a temperature sensor 17E. The rest of the refrigeration cycle device 1004 is constructed similarly to the Fig. 1 and will therefore not be described repeatedly.

[0035] The cooling device 17D in the fourth embodiment includes an internal heat exchanger 172. The internal heat exchanger 172 is configured so that the refrigerant in the bypass flow path BP, after passing through the heat exchanger 19, and a fluid (refrigerator oil and / or gaseous refrigerant) passing through the oil measurement path 17B exchange heat.

[0036] The oil measurement path 17B has a suction inlet P3 that is set to a predetermined level on the oil separator 11. The suction inlet P3 is higher in level than an oil discharge outlet P4 of the oil separator 11 and lower in level than a gas flow inlet P1 and a gas discharge outlet P2.

[0037] The solenoid valve 17C, the internal heat exchanger 17B, and the temperature sensor 17E are arranged in this order along the oil measurement path 17B. The oil measurement path 17B merges into the oil return path at a junction point P5 upstream of the flow rate adjustment mechanism 16.

[0038] Also in the fourth embodiment, the design of the internal heat exchanger 172, which contains the Fig. 5 and Fig. 6 causes the detection of an oil level.

[0039] Like the third embodiment, the fourth embodiment can also prevent increased work of the compressor 10 and thus a reduced COP. Furthermore, the expansion valve 20 can be used to control the flow rate of the refrigerant flowing through the bypass flow path BP, so that the amount of heat exchanged in the heat exchanger 172 can be adjusted to any desired value, and even when the state of the refrigeration cycle changes, it can be handled over a wide range, facilitating the design of the heat exchanger 172. Fifth embodiment.

[0040] In a fifth embodiment, a first concrete example of the flow rate adjustment mechanism explained in the first embodiment will be explained. Fig. Fig. 8 is a diagram showing a configuration of a refrigeration cycle device according to the fifth embodiment. Fig. The refrigeration cycle device 1005 shown in Fig. 8 includes a linear expansion valve (LEV) 16A as a flow rate adjusting mechanism 16. The rest of the refrigeration cycle device 1005 is constructed similarly to the one shown in Fig. 1 and will therefore not be described repeatedly.

[0041] The use of the linear expansion valve 16A enables the control unit 600 to increase / decrease a flow rate of a fluid (refrigerant and refrigerating machine oil) flowing through the oil return path RP in response to an output of the oil amount measuring device 17.

[0042] In the fifth embodiment, the oil quantity measuring device 17 may have any of the configurations described in the second to fourth embodiments. Furthermore, the control unit 600 may apply the control described in the first embodiment to control a flow rate. Sixth embodiment.

[0043] In a sixth embodiment, a second concrete example of the flow rate adjustment mechanism explained in the first embodiment will be explained. Fig. 9 is a diagram showing a configuration of a refrigeration cycle device according to the sixth embodiment. In a Fig. In the refrigeration cycle device 1006 shown in Figure 9, the flow rate adjustment mechanism 16 comprises a solenoid valve 16B and a capillary line 16C arranged in series on the oil return path RP. The rest of the refrigeration cycle device 1006 is constructed similarly to the Fig. 1 and will therefore not be described repeatedly.

[0044] As described above, the oil return path RP is equipped with a capillary tube 16C and a solenoid valve 16B. The solenoid valve 16B is controlled to open when the flow rate is increased, and the solenoid valve 16B is controlled to close when the flow rate is decreased. Thus, the control unit 600 can adjust a flow rate of the refrigerant and refrigeration oil passing through the oil return path RP.

[0045] In the sixth embodiment, the oil quantity measuring device 17 may have any of the configurations described in the second to fourth embodiments. Furthermore, the control unit 600 may apply the control described in the first embodiment to control a flow rate.

[0046] When the oil return path RP is equipped with an LEV, as explained in the fifth embodiment, a component other than the expansion valve 14 is preferably used. The oil return path RP carries the refrigeration oil and high-temperature refrigerant discharged from the compressor 10, which is why the LEV must be particularly heat-resistant. The LEV in the oil return path RP, as shown in Fig. 8, therefore, requires a special specification and can be a cost-intensive component. A capillary tube and a solenoid valve, on the other hand, are simple in design and significantly more heat-resistant, allowing common components to be used for the oil return path and the flow rate adjustment mechanism to be designed cost-effectively. Seventh embodiment.

[0047] In a seventh embodiment, a third concrete example of the flow rate adjustment mechanism explained in the first embodiment will be explained. Fig. 10 is a diagram showing a configuration of a refrigeration cycle device according to the seventh embodiment. In a Fig. In the refrigeration cycle device 1007 shown in Figure 10, the oil return path RP branches at a branching point BP1 into a flow path RP1 and a flow path RP2, which are then joined at a merging point MP1. The flow rate adjusting mechanism 16 includes a solenoid valve 16B and a capillary tube 16C arranged in series on the flow path RP1, and a capillary tube 16D arranged in the flow path RP2.

[0048] In the seventh embodiment, the oil quantity measuring device 17 may have any of the configurations described in the second to fourth embodiments. Furthermore, the control unit 600 may apply the control described in the first embodiment to control a flow rate.

[0049] As in Fig. As shown in Figure 10, the oil return path RP branches into parallel flow paths RP1 and RP2, which are equipped with capillary lines 16C and 16D, respectively, and one flow path RP1 is equipped with a solenoid valve 16B. The control unit 600 can adjust a flow rate by opening the solenoid valve 16B when the flow rate is to be increased and closing the solenoid valve 16B when the flow rate is to be decreased.

[0050] At the Fig. In the configuration shown in Figure 9, the flow rate is set to zero when the flow rate is reduced, while in the configuration shown in Fig. 10, a certain amount of refrigeration oil can be returned to the compressor 10 even if the flow rate is reduced. Eighth embodiment.

[0051] In the first embodiment, during operation of the refrigeration cycle device, the amount of refrigerant flowing through the oil return path RP is continuously monitored, and the flow rate adjustment mechanism 16 regulates the flow rate. The flow rate adjustment mechanism 16 also includes a moving part, so it is advantageous for the longevity of the device if the moving part is moved less frequently.

[0052] Accordingly, in an eighth embodiment, the Fig. 2 is only applied in a situation where the refrigerant flows easily into the oil return path RP.

[0053] Fig. 11 is a flowchart illustrating how a flow rate adjustment mechanism according to the eighth embodiment is controlled. In step S11, the control unit 600 determines whether a condition for determining whether to apply the flow rate adjustment control is met.

[0054] For example, the control unit 600 determines that the condition of step S11 is met when the operating frequency of the compressor 10 is lower than a reference frequency. The reference frequency may be a frequency that is, for example, half the upper limit of the compressor's operating frequency.

[0055] When the compressor 10 has a low operating frequency, the compressor 10 discharges a reduced amount of refrigeration oil. The oil separator 11 contains a reduced amount of refrigeration oil, and refrigerant is thus more easily returned to the oil return path RP. Conversely, when the oil separator 11 contains a large amount of refrigeration oil, the oil return path RP primarily carries refrigeration oil, and the COP is unlikely to decrease due to the presence of the oil return path. Therefore, the determination of whether to apply flow rate adjustment control is made based on the compressor's operating frequency, as described above.

[0056] Note that the condition for applying flow rate adjustment control is not limited to this. For example, the control unit 600 may determine that the condition for applying flow rate adjustment control is met in step S11 when a pressure difference between the inlet and outlet of the compressor 10 is smaller than a reference threshold. In this case, the reference threshold may be half of a maximum value of the pressure difference.

[0057] For a given diameter of a fluid passage restrictor of the flow rate adjustment mechanism, a larger differential pressure increases the amount of fluid passing through the oil return path RP, thus promoting refrigerant recirculation. Therefore, the determination of whether to apply flow rate adjustment control can be made based on the magnitude of the differential pressure, as described above.

[0058] If the condition for applying flow rate adjustment control is not met (NO in S11), the control unit 600 sets a flow rate of the flow rate adjustment mechanism 16 to a default value in step S15. This allows the flow rate adjustment mechanism 16 to have a moving part that needs to be moved less frequently, which is beneficial for the longevity of the product.

[0059] If the condition for applying the flow rate adjustment control is met (YES in S11), the control unit 600 proceeds to step S12 to determine whether there is a reduced amount of refrigeration oil in the oil separator 11 based on an output of the oil amount measuring device 17. If there is an insufficient amount of refrigeration oil in the oil separator 11, there is a possibility that refrigerant may flow through the oil return path RP.

[0060] When the oil separator has a reduced amount of refrigerating machine oil (YES in S12), the control unit 600 controls the flow rate adjusting mechanism 16 to reduce a flow rate of a fluid flowing through the oil return path RP in step S13.

[0061] On the other hand, when the oil separator does not have a reduced amount of refrigerating oil (NO in S12), the control unit 600 controls the flow rate adjusting mechanism 16 to increase the flow rate of the fluid flowing through the oil return path RP in step S14.

[0062] Thus, by controlling the flow rate adjustment mechanism 16, a certain amount of refrigeration oil can be retained in the oil separator 11 to reduce the amount of bypass refrigerant flowing through the oil return path RP when the oil separator has a reduced amount of refrigeration oil. This can prevent refrigerant that does not contribute to the cooling capacity from circulating through the compressor 10 and the oil return path RP, thus preventing increased work of the compressor 10 and thus a reduced COP.

[0063] In the eighth embodiment, the oil quantity measuring device 17 may have any of the configurations described in the second to fourth embodiments. Furthermore, the flow rate adjusting mechanism 16 may have any of the configurations described in the fifth to seventh embodiments.

[0064] The eighth embodiment can achieve a similar effect to the first to seventh embodiments and further make the flow rate adjusting mechanism 16 longer in durability than the first to seventh embodiments. (Summary)

[0065] Reference is again made to the drawings below to summarize the embodiments. (1) A Fig. The refrigeration cycle device 1001 of the present disclosure, illustrated in FIG. 1, includes 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 form a refrigerant circuit C1 through which refrigerant circulates. The refrigeration cycle device 1001 further includes an oil return path RP configured to return refrigerating oil from the oil separator 11 to the inlet of the compressor 10, a flow rate adjusting mechanism 16 disposed on the oil return path RP, and an oil amount measuring device 17 configured to detect an amount of refrigerating oil stored in the oil separator 11. The flow rate adjusting mechanism 16 is configured to operate in response to an output of the oil amount measuring device 17 to regulate a flow rate of a fluid passing through the oil return path RP. (2) In Section 1, as in Fig. 3, the oil quantity measuring device 17 comprises an oil level sensor 17A which is configured to detect a level of a surface of oil in the oil separator. (3) In Section 1, as in Fig. 4, the oil quantity measuring device 17 comprises an oil measuring path 17B which is connected to the oil separator 11 at a suction inlet P3 which is higher in level than an oil discharge outlet P4, at which the oil return path RP is connected at one end to the oil separator 11, and which is connected to the oil return path RP at a merging point P5 provided on the oil return path RP, a cooling device 17D which is configured to cool a fluid passing through the oil measuring path 17B, and a temperature sensor 17E which is configured to detect a temperature of a portion of the oil measuring path 17B after passing through the cooling device 17D. (4) In Section 3, as in Fig. 4, the cooling device 17D comprises a heat exchanger 171 configured to exchange heat between refrigerant conducted in the refrigerant circuit C1 from the heat exchanger 15 to the compressor 10 and the fluid passing through the oil measuring path 17B. (5) In paragraph 3, as in Fig. As shown in Figure 7, the refrigeration cycle device 1004 further includes a bypass flow path BP configured to divert a portion of the refrigerant flowing in the refrigerant circuit C1 from the heat exchanger 13 to the expansion valve 14 and return the portion to the compressor 10. The cooling device 17D includes a heat exchanger 172 configured to exchange heat between refrigerant passing through the bypass flow path BP and the fluid passing through the oil measurement path 17B. (6) In any of Sections 1 to 5, as defined in Fig. 8, the flow rate adjusting mechanism 16 includes a linear expansion valve 16A. (7) In any of Sections 1 to 5, as defined in Fig. 9, the flow rate adjusting mechanism 16 includes a solenoid valve 16B and a capillary line 16C arranged in series on the oil return path RP. (8) In any of Sections 1 to 5, as defined in Fig. As shown in Figure 10, the oil return path RP branches into a flow path RP1 and a flow path RP2 at a branching point BP1, and the flow paths RP1 and RP2 are subsequently joined at a merging point MP. The flow rate adjusting mechanism 16 includes a solenoid valve 16B and a capillary line 16C arranged in series on the flow path RP1, and a capillary line 16D arranged in the flow path RP2. (9) In any of sections 1 to 8, the refrigeration cycle device 1001 further comprises a control unit 600 configured to control the compressor 10 and a flow rate adjustment mechanism 16. As shown in Fig. As shown in Figure 11, the control unit 600 is configured to apply a first control (S15) or a second control (S12 to S14) while the compressor 10 is operating. The control unit 600 is configured to set a flow rate of the flow rate adjustment mechanism 16 in the first control. The control unit 600 is configured to control a flow rate of the flow rate adjustment mechanism 16 in response to the output of the oil quantity measuring device 17 in the second control. (10) In Section 9, as in Fig. As shown in Figure 11, the control unit 600 is configured to apply the first control (S15) when the operating frequency of the compressor 10 is higher than a threshold value, and to apply the second control (S12 to S14) when the operating frequency of the compressor is lower than the threshold value. (11) In Section 9, as in Fig. As shown in Figure 11, the control unit 600 is configured to apply the first control (S15) when a pressure difference between the inlet and the outlet of the compressor 10 is less than a threshold value, and to apply the second control (S12 to S14) when the pressure difference is lower than the threshold value.

[0066] It is to be understood that the embodiments disclosed herein are in all respects illustrative and not restrictive. The scope of the present disclosure is defined by the terms of the claims rather than by the above description of the embodiments, and is intended to include all changes within the meaning and scope of the claims that are consistent with the terms of the claims. LIST OF REFERENCE SYMBOLS

[0067] 10 Compressor, 11 Oil separator, 13, 15, 19, 171, 172 Heat exchanger, 14, 20 Expansion valve, 16 Flow rate adjusting mechanism, 16A Linear expansion valve, 16B, 17C Solenoid valve, 16C, 16D Capillary tube, 17 Oil quantity measuring device, 17A Oil level sensor, 17B Oil measuring path, 17D Cooling device, 17E Temperature sensor, 600 Control unit, 601 CPU, 602 Memory, 1001-1007 Refrigeration cycle device, BP Bypass flow path, BP1 Branch point, C1 Refrigerant circuit, MP, MP1, P5 Merge point, P1 Gas flow inlet, P2 Gas discharge outlet, P3 Suction inlet, P4 Oil discharge outlet, RP oil return path, RP1, RP2 flow path. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 3874980

[0002] JP 3874980 [0003, 0004]

Claims

[1] Refrigeration cycle device comprising: a compressor, an oil separator, a first heat exchanger, an expansion valve and a second heat exchanger, wherein the compressor, the oil separator, the first heat exchanger, the expansion valve and the second heat exchanger form a refrigerant circuit through which refrigerant circulates; an oil return path configured to return refrigeration oil from the oil separator to an inlet of the compressor; a flow rate adjusting mechanism disposed in the oil return path; and an oil quantity measuring device which is arranged to detect a quantity of refrigeration oil which is stored in the oil separator, wherein the flow rate adjusting mechanism is configured to operate in response to an output of the oil quantity measuring device to regulate a flow rate of a fluid passing through the oil return path. [2] The refrigeration cycle device according to claim 1, wherein the oil amount measuring means comprises an oil level sensor configured to detect a level of a surface of oil in the oil separator. [3] The refrigeration cycle device according to claim 1, wherein the oil quantity measuring device comprises: an oil measuring path connected to the oil separator at a position higher in level than a position at which one end of the oil return path is connected to the oil separator, and connected to the oil return path at a connection point provided on the oil return path; a cooling device configured to cool a fluid passing through the oil measuring path; and a temperature sensor configured to detect a temperature of a portion of the oil measuring path after passing the cooling device. [4] The refrigeration cycle device according to claim 3, wherein the cooling device comprises a third heat exchanger configured to exchange heat between refrigerant passed in the refrigerant circuit from the second heat exchanger to the compressor and the fluid passing through the oil measuring path. [5] The refrigeration cycle device according to claim 3, further comprising a bypass flow path configured to branch off a portion of the refrigerant flowing in the refrigerant circuit from the first heat exchanger to the expansion valve and return this portion to the compressor, wherein the cooling device comprises a third heat exchanger configured to exchange heat between refrigerant passing through the bypass flow path and the fluid passing through the oil measurement path. [6] The refrigeration cycle device according to any one of claims 1 to 5, wherein the flow rate adjusting mechanism comprises a linear expansion valve. [7] The refrigeration cycle device according to any one of claims 1 to 5, wherein the flow path adjusting mechanism comprises a solenoid valve and a capillary tube arranged in series on the oil return path. [8] Refrigeration cycle device according to one of claims 1 to 5, wherein the oil return path branches into a first flow path and a second flow path at a branching point, the first and second flow paths subsequently being joined at a merging point, and the flow rate adjustment mechanism includes: a solenoid valve and a first capillary line arranged in series in the first flow path; and a second capillary line arranged on the second flow path. [9] The refrigeration cycle device according to any one of claims 1 to 8, further comprising a control unit configured to control the compressor and the flow rate adjusting mechanism, the control unit configured to apply a first control or a second control while the compressor is operating, the control unit configured to set a flow rate of the flow rate adjusting mechanism in the first control, the control unit configured to control a flow rate of the flow rate adjusting mechanism in response to the output of the oil amount measuring device in the second control. [10] The refrigeration cycle device according to claim 9, wherein the control unit is configured to apply the first control when the operating frequency of the compressor is higher than a threshold value and to apply the second control when the operating frequency of the compressor is lower than the threshold value. [11] The refrigeration cycle device according to claim 9, wherein the control unit is configured to apply the first control when a pressure difference between the inlet of the compressor and an outlet of the compressor is less than a threshold value, and to apply the second control when the pressure difference is greater than the threshold value.

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