Refrigerant circulation system

Abstract

To reliably supply oil to a sliding bearing of a motor at the time of vehicle start-up in a refrigerant circulation system which lubricates the sliding bearing with the refrigerant containing the oil.SOLUTION: A refrigerator circulation system 100 comprises: a compressor 3 compressing a refrigerant which is CO2 containing oil; a motor 1 including a rotor 11 and a stator 12, a rotating shaft 13 connected to the rotor, and a sliding bearing 14 supporting the rotating shaft, and configured to be supplied with the refrigerant compressed by the compressor and to have the sliding bearing lubricated by the refrigerant; refrigerant passages (first passages) 16a to 16d to supply the refrigerant from the compressor to the motor and refrigerant passages (second passages) 17a and 17b to supply the refrigerant from the motor to the compressor; a first valve 31 installed on the first passage and a second valve 32 installed on the second passage; and a control device 50 which closes the first and second valves when a vehicle is stopped.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a refrigerant circulation system that is mounted on a vehicle and circulates a refrigerant containing oil. [Background technology]

[0002] Conventionally, refrigeration cycles used in air conditioners and the like have used refrigerant circulation systems that circulate refrigerant through compressors, heat exchangers, etc. In this type of refrigerant circulation system, a refrigerant containing oil (refrigeration oil) is generally used to lubricate and seal the compressor, and this oil also circulates within the system.

[0003] When starting up a refrigerant circulation system like the one described above, the oil supply to the compressor can be insufficient. This is thought to be because the oil in the compressor, which was at high pressure during operation, leaks to the low-pressure side when the system is shut down, resulting in a decrease in the oil in the compressor. Furthermore, it is thought that when the system is shut down, the refrigerant dissolves in the oil in the compressor, causing the refrigerant to vaporize when the compressor is started, resulting in a large amount of oil mist leaking out of the compressor.

[0004] To address this problem, for example, Patent Document 1 discloses a technology in which, when the system is started, the oil-containing refrigerant discharged from the compressor is separated to extract the oil, and only the oil is supplied to the suction side of the compressor, thereby ensuring sufficient lubrication of the compressor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-170457 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, rolling bearings and sliding bearings have traditionally been used as bearings to support the rotating shaft of, for example, a vehicle's power source (engine or motor). However, when rolling bearings are used in motors such as electric vehicles, the rotating shaft of the motor rotates at high speeds of, for example, over 30,000 rpm, causing problems with rolling fatigue and shortening the bearing's lifespan. On the other hand, when a typical sliding bearing that uses oil as a lubricant is used in a motor, loss due to oil agitation resistance caused by the motor's rotating shaft increases.

[0007] Therefore, the present inventors considered applying a motor to a refrigerant circulation system such as the one described above, and applying a sliding bearing to the motor's rotating shaft that uses, as a lubricant, the refrigerant circulated in this system, particularly a CO2 refrigerant that liquefies when compressed by a compressor. In this case, too, it is desirable to use a refrigerant that contains oil (refrigerating machine oil), as described above, to ensure the lubrication of the motor's sliding bearing. It is also desirable to be able to reliably supply such oil to the motor's sliding bearing when the system starts.

[0008] The present invention has been made to solve the problems of the conventional technology described above, and has an object to reliably supply oil to the sliding bearings when a vehicle is started in a refrigerant circulation system that circulates an oil-containing refrigerant and uses this refrigerant to lubricate the sliding bearings of a motor. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a refrigerant circulation system that is mounted on a vehicle and circulates a refrigerant made of CO2 containing oil, the system comprising: a compressor that compresses the refrigerant, a rotor and a stator, a rotating shaft connected to the rotor, and a sliding bearing that supports the rotating shaft, a motor configured to receive the refrigerant compressed by the compressor and to lubricate the sliding bearing using the refrigerant as a lubricant; a first passage for supplying refrigerant from the compressor to the motor, and a second passage for supplying refrigerant from the motor to the compressor, a first valve provided on the first passage, and a second valve provided on the second passage; and a control device configured to control the first valve, the second valve, and the compressor, wherein the control device is configured to close the first valve and the second valve when the vehicle is stopped.

[0010] In the present invention configured in this manner, when the vehicle is stopped, the first and second valves, located upstream and downstream of the motor, respectively, are closed. This prevents the refrigerant (a refrigerant primarily composed of CO2 and containing oil) from continuing to move through the refrigerant passage while the vehicle is stopped; specifically, prevents the refrigerant from moving from the relatively high-pressure first passage to the relatively low-pressure second passage. As a result, when the vehicle is started, the refrigerant oil in the first passage, located upstream of the motor, can be reliably supplied to the motor's sliding bearings, preventing a shortage of oil supply to the sliding bearings. This allows the refrigerant oil to adequately lubricate the motor's sliding bearings during startup, preventing high friction, wear, and seizure in the sliding bearings.

[0011] In the present invention, preferably, the refrigerant circulation system further includes a receiver tank provided on the second passage downstream of the second valve for storing refrigerant compressed by the compressor, a third passage for supplying refrigerant from the upstream side of the first valve on the first passage to the receiver tank, a third valve provided on the second passage downstream of the receiver tank, and a fourth valve provided on the third passage, and the control device is configured to close the third valve and open the fourth valve when the vehicle is stopped, with the first valve and the second valve closed, to operate the compressor. According to the present invention configured as described above, when the vehicle is stopped, the refrigerant compressed by the compressor can be stored in the receiver tank, and when the vehicle is started, the refrigerant stored in the receiver tank can be supplied to the compressor. This ensures that refrigerant oil is supplied to the compressor at start-up, thereby preventing a shortage of oil supply to the compressor.

[0012] In the present invention, the control device is preferably configured to operate the compressor when the vehicle is started, and to maintain the first valve and the second valve in a closed state for a predetermined time, and then open the first valve and the second valve. According to the present invention configured as described above, by operating the compressor with the first and second valves closed immediately after starting the vehicle, the pressure downstream of the motor can be made lower than the pressure upstream of the motor, thereby preventing backflow of the refrigerant when the first and second valves are subsequently opened.

[0013] In the present invention, the control device is preferably configured to, when the vehicle stops, operate the compressor, maintain the first valve and the second valve in an open state for a predetermined time, and then close the first valve and the second valve. According to the present invention configured in this manner, immediately after the vehicle is stopped, the compressor is operated with the first and second valves open, and then these first and second valves are closed, so oil can be collected around the motor when the vehicle is stopped. The oil collected around the motor in this way is supplied to the sliding bearing when the vehicle is started, making it possible to effectively prevent a shortage of oil supply to the sliding bearing.

[0014] In the present invention, the first passage preferably includes a passage for supplying the coolant to the rotor or stator of the motor, in addition to a passage for supplying the coolant to the sliding bearing of the motor. According to the present invention configured in this manner, the refrigerant can be used to both lubricate and cool the motor, which makes it possible to simplify the system and reduce costs compared to systems that perform these functions separately. [Effects of the Invention]

[0015] According to the present invention, in a refrigerant circulation system in which an oil-containing refrigerant is circulated and the refrigerant is used to lubricate the sliding bearings of a motor, oil can be reliably supplied to the sliding bearings when the vehicle is started. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram of a vehicle to which a refrigerant circulation system according to an embodiment of the present invention is applied; [Figure 2] 1 is a schematic configuration diagram of a motor according to an embodiment of the present invention. [Figure 3] 1 is a schematic configuration diagram of a refrigerant circulation system according to an embodiment of the present invention. [Figure 4] 1 is a block diagram showing an electrical configuration of a refrigerant circulation system according to an embodiment of the present invention. [Figure 5] 4 is a time chart showing valve control according to an embodiment of the present invention. [Figure 6] FIG. 4 is an explanatory diagram of valve control performed at startup in the embodiment of the present invention. [Figure 7]FIG. 2 is an explanatory diagram of valve control performed when the vehicle is stopped (stop 1) in the embodiment of the present invention. [Figure 8] FIG. 10 is an explanatory diagram of valve control performed when the vehicle is stopped (stop 2) in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a refrigerant circulation system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0018] [Overall configuration] First, the overall configuration of a refrigerant circulation system according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of a vehicle to which the refrigerant circulation system according to this embodiment is applied.

[0019] 1, vehicle 200 is, for example, an electric vehicle, and has a refrigerant circulation system 100 that circulates a refrigerant in a refrigeration cycle. This refrigerant circulation system 100 has a motor (electric motor) 1 that generates power to drive vehicle 200, a compressor (compressor) 3 that compresses the refrigerant to be supplied to motor 1, and a heat exchanger (condenser) 5 that includes a condenser, a fan, etc., and that cools the refrigerant compressed by compressor 3.

[0020] The refrigerant circulation system 100 circulates a CO2 refrigerant as a natural refrigerant. To this end, the compressor 3 is configured to compress the refrigerant to extremely high pressures. The motor 1 is configured to function as an expansion valve and an evaporator in a refrigeration cycle by using the refrigerant compressed by the compressor 3 to lubricate the sliding bearings that support the rotating shaft and to cool the rotor and stator (details will be described later). For example, in the refrigerant circulation system 100, a high-temperature liquid refrigerant is supplied from the compressor 3 to the heat exchanger 5, a low-temperature liquid refrigerant is supplied from the heat exchanger 5 to the motor 1, and a high-temperature gaseous refrigerant is supplied from the motor 1 to the compressor 3. In this case, the motor 1 is cooled by the latent heat of vaporization of the refrigerant. The refrigerant circulated by the refrigerant circulation system 100 may also be used for an air conditioner that conditions the interior of the vehicle 200.

[0021] In particular, the refrigerant circulation system 100 circulates a refrigerant in which CO2 is mixed with oil (refrigerating machine oil such as PAG, including additives). Such oil is easily soluble in the refrigerant in the liquid phase, and the solubility (content) increases particularly as the refrigerant pressure increases. However, in the gas phase, the oil is almost insoluble in the refrigerant.

[0022] [Motor configuration] Next, the configuration of the motor 1 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic diagram of the motor 1 according to this embodiment. Specifically, Fig. 2 is a cross-sectional view of the motor 1 as seen along the axial direction.

[0023] As shown in Figure 2, the motor 1 is a system that mainly includes a rotor 11, a stator 12, a rotating shaft 13 that is connected to the rotor 11 and has one end connected to a transaxle (not shown) of the vehicle 200, a pair of plain bearings 14 that support the rotating shaft 13, and a housing 15 that houses the rotor 11, stator 12, rotating shaft 13, plain bearings 14, etc.

[0024] The motor 1 also has refrigerant passages 16a, 16b that supply the refrigerant compressed by the compressor 3 to the sliding bearing 14 and the stator 12, respectively. Specifically, the refrigerant passage 16a supplies the refrigerant to the gap between the rotating shaft 13 and the sliding bearing 14. The sliding bearing 14 is configured to be lubricated using the refrigerant (CO2 refrigerant) supplied from the refrigerant passage 16a in this manner as a lubricant. Typically, the sliding bearing 14 is lubricated using a liquid refrigerant.

[0025] If a rolling bearing is applied to the motor 1, for example in an electric vehicle, the rotating shaft 13 of the motor 1 rotates at a high rotation speed of, for example, over 30,000 rpm, causing a problem of shortened lifespan due to rolling fatigue. On the other hand, if a general sliding bearing that uses oil is applied to the motor 1, the loss of oil agitation resistance caused by the rotating shaft 13 becomes large. Therefore, in this embodiment, a sliding bearing 14 that uses a refrigerant (CO2 refrigerant) that has been liquefied by compression by the compressor 3 is applied to the motor 1. This solves problems such as rolling fatigue and oil agitation resistance.

[0026] The refrigerant supplied from refrigerant passage 16b is used to cool stator 12, more specifically, to cool the coil (not shown) of stator 12. In particular, stator 12 is supplied with refrigerant that has been expanded and reduced in pressure by expansion valve 19 provided on refrigerant passage 16b. The refrigerant used to cool stator 12 and the refrigerant used to lubricate sliding bearing 14 as described above is discharged from refrigerant passage 17a of motor 1 and returned to compressor 3 (FIG. 1).

[0027] In this motor 1, the expansion valve 19 in the refrigerant passage 16b functions as an expansion valve in the refrigeration cycle. The motor 1 is also configured to supply the refrigerant from the gap between the rotating shaft 13 and the sliding bearing 14 to the space within the housing 15 in which the rotor 11 and the stator 12 are provided, thereby reducing the pressure of the refrigerant, and this configuration also functions as an expansion valve in the refrigeration cycle. As described above, the motor 1 is also configured to exchange heat (cool) the refrigerant with the stator 12 and other components that are relatively hot, and therefore also functions as an evaporator in the refrigeration cycle. In a motor in which a coil is provided on the rotor 11 instead of the stator 12, a refrigerant may be used to cool the coil of the rotor 11.

[0028] Furthermore, motor 1 further has a seal member 18 for sealing sliding bearing 14 provided on the side of rotating shaft 13 that is connected to a transaxle or the like. This seal member 18 is provided in housing 15 so as to prevent refrigerant from leaking to the outside from the gap between sliding bearing 14 and rotating shaft 13. On the other hand, such a seal member 18 is not provided on sliding bearing 14 on the opposite side to the side of rotating shaft 13 that is connected to a transaxle or the like, and the gap between sliding bearing 14 and rotating shaft 13 is sealed by being covered by housing 15.

[0029] [Specific configuration of the refrigerant circulation system] Next, the refrigerant circulation system 100 according to this embodiment will be specifically described with reference to Fig. 3. Fig. 3 is a schematic diagram of the refrigerant circulation system 100 according to this embodiment.

[0030] As shown in FIG. 3, the refrigerant circulation system 100 includes the motor 1, compressor 3, and heat exchanger 5 described above, as well as refrigerant passages (first passages) 16a-16d for supplying refrigerant from the compressor 3 to the motor 1 and refrigerant passages (second passages) 17a and 17b for supplying refrigerant from the motor 1 to the compressor 3. Refrigerant passages 16a and 16b are passages for supplying refrigerant to the sliding bearing 14 and stator 12 of the motor 1, respectively (FIG. 2). Refrigerant passage 16c is a passage connecting the compressor 3 and the heat exchanger 5, and refrigerant passage 16d is a passage connecting the heat exchanger 5 and the refrigerant passages 16a and 16b. More specifically, the refrigerant passages 16a, 16b, and 16d are connected via a first valve 31 serving as a three-way valve. A check valve 36 is provided in the refrigerant passage 16c.

[0031] The refrigerant circulation system 100 also includes a receiver tank 7 on refrigerant passages 17a and 17b for storing the refrigerant compressed by the compressor 3. The refrigerant passages 17a and 17b are passages located upstream and downstream of the receiver tank 7, respectively, and the refrigerant circulation system 100 includes a second valve 32 and a third valve 33 provided on these refrigerant passages 17a and 17b, respectively. The refrigerant circulation system 100 also includes a refrigerant passage (third passage) 20 that connects the refrigerant passage 16d upstream of the first valve 31 to the refrigerant passage 17b downstream of the receiver tank 7 (specifically, upstream of the third valve 33), and a fourth valve 34 provided on this refrigerant passage 20. The second to fourth valves 32 to 34 are configured as so-called gate valves.

[0032] Furthermore, the refrigerant circulation system 100 has a flow rate sensor 40 provided on the refrigerant passage 16c for detecting the flow rate of the refrigerant, a first pressure sensor 41 provided on the refrigerant passage 16b for detecting the pressure of the refrigerant, and a second pressure sensor 42 for detecting the pressure in the receiver tank 7 (the pressure of the stored refrigerant).

[0033] Next, the electrical configuration of the refrigerant circulation system 100 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing the electrical configuration of the refrigerant circulation system 100 according to this embodiment.

[0034] 4, the refrigerant circulation system 100 includes a control device 50 in addition to the above-described flow rate sensor 40, first and second pressure sensors 41, 42, motor 1, compressor 3, expansion valve 19, and first to fourth valves 31 to 34. The control device 50 is configured by a computer including one or more processors 50a (typically a CPU) and memory 50b such as a ROM or RAM that stores various programs interpreted and executed on the processor 50a (including basic control programs such as an OS and application programs that are started on the OS and realize specific functions) and various data.

[0035] Specifically, the control device 50 controls the motor 1, the compressor 3, the expansion valve 19, and the first to fourth valves 31 to 34 based on the flow rate and pressure detected by the flow rate sensor 40 and the first and second pressure sensors 41 and 42. In particular, in this embodiment, the control device 50 controls the first to fourth valves 31 to 34 (hereinafter also simply referred to as "valve control") when the vehicle 200 is stopped and started, so as to ensure that the oil contained in the refrigerant is supplied to the motor 1 and the compressor 3 when the vehicle 200 is started.

[0036] Next, valve control performed by the control device 50 of the refrigerant circulation system 100 according to this embodiment will be described in detail with reference to Figures 5 to 8. Figure 5 is a time chart showing valve control according to this embodiment. Figure 6 is an explanatory diagram of the refrigerant flow and pressure due to valve control performed at start-up in this embodiment. Figure 7 is an explanatory diagram of the refrigerant flow and pressure due to valve control performed when the vehicle 200 is stopped (immediately after the vehicle 200 has stopped, referred to as "stop time 1") in this embodiment. Figure 8 is an explanatory diagram of the refrigerant flow and pressure due to valve control performed when the vehicle is stopped (immediately after stop time 1, referred to as "stop time 2") in this embodiment.

[0037] As shown in FIG. 5, at time t1, the vehicle 200 starts (the vehicle power supply (main switch) is turned on), and the control device 50 first starts to open the expansion valve 19 while maintaining the first and second valves 31, 32 in a closed state. Thereafter, at time t2, a predetermined time after time t1, the control device 50 switches the first and second valves 31, 32 from a closed state to an open state. Note that the control device 50 maintains the third valve 33 in an open state and the fourth valve 34 in a closed state from time t1 onwards (specifically, from the time the vehicle 200 starts until the vehicle 200 stops). In addition, the control device 50 operates at least the compressor 3 from time t1 onwards.

[0038] Such valve control between times t1 and t2 will be further described with reference to Fig. 6. As shown in Fig. 6, when the compressor 3 operates with the first and second valves 31 and 32 closed, the pressure upstream of the compressor 3, specifically the pressure in the refrigerant passages 17b and 20, increases. In this case, the refrigerant stored in the receiver tank 7 when the vehicle 200 is stopped (details will be described later) is supplied to the compressor 3, allowing the compressor 3 to be appropriately lubricated using oil. Furthermore, because the pressure of the refrigerant upstream of the compressor 3 is relatively high, a refrigerant with a high oil content can be supplied to the compressor 3, allowing the compressor 3 to be more appropriately lubricated.

[0039] Furthermore, from time t1 to t2, the refrigerant that had collected in refrigerant passages 16a, 16b while vehicle 200 was stopped, that is, the refrigerant that had collected upstream near motor 1 (details will be described later), is supplied to motor 1, allowing the sliding bearing 14 of motor 1 to be properly lubricated using oil. In this case, because the pressure of the refrigerant upstream of motor 1 is relatively high, a refrigerant with a high oil content can be supplied to motor 1, allowing the sliding bearing 14 of motor 1 to be more properly lubricated.

[0040] The control device 50 opens the first and second valves 31, 32 at time t2 after time t1 when the vehicle 200 is started. This time t2 is determined based on the timing at which the pressure detected by the first pressure sensor 41 and the pressure detected by the second pressure sensor 42 become the same. In other words, the predetermined time from time t1 to time t2 is determined based on the timing at which the pressures detected by the first and second pressure sensors 41, 42 become the same. This is because, if the pressures detected by the first and second pressure sensors 41, 42 are different, specifically, if the pressure detected by the second pressure sensor 42 is higher than the pressure detected by the first pressure sensor 41 (i.e., when the pressure downstream of the motor 1 is higher than the pressure upstream of the motor 1), opening the first and second valves 31, 32 may cause the refrigerant to flow back.

[0041] Returning to FIG. 5, at time t3, when the vehicle 200 is stopped (the vehicle power supply (main switch) is turned off), the control device 50 first closes the expansion valve 19 while maintaining the first and second valves 31, 32 in an open state. Thereafter, at time t4, a predetermined time after time t3, the control device 50 switches the first and second valves 31, 32 from open to closed, switches the third valve 33 from open to closed, and switches the fourth valve 34 from closed to open. Thereafter, at time t5, the control device 50 switches the third valve 33 from closed to open, and switches the fourth valve 34 from open to closed. Note that from time t3 to t5 after the vehicle 200 is stopped, the control device 50 stops the motor 1 but continues to operate the compressor 3.

[0042] Valve control from time t3 to t4 (stop time 1) will be further explained with reference to Figure 7. As shown in Figure 7, when motor 1 is stopped and expansion valve 19 is closed, compressor 3 operates, increasing the pressure downstream of compressor 3, specifically the pressure in refrigerant passages 16a to 16d. As a result, refrigerant can be collected upstream near motor 1, that is, in refrigerant passages 16a and 16b near motor 1. As described above, the refrigerant collected in this manner can be used appropriately to lubricate sliding bearing 14 of motor 1 when vehicle 200 is started.

[0043] The control device 50 closes the first and second valves 31, 32 at time t4, which is after time t3 when the vehicle 200 stops. This time t4 is determined based on the timing at which the pressure detected by the first pressure sensor 41 reaches or exceeds a predetermined value. In other words, the predetermined time from time t3 to time t4 is determined based on the timing at which the pressure detected by the first pressure sensor 41 reaches or exceeds a predetermined value. This is because, when the pressure detected by the first pressure sensor 41 is low, typically when the pressure upstream of the motor 1 is lower than the pressure downstream of the motor 1, closing and opening the first and second valves 31, 32 may cause the refrigerant to flow backward near the motor 1.

[0044] Next, valve control from time t4 to t5 (stop time 2) will be further described with reference to Fig. 8. As shown in Fig. 8, when the first to third valves 31 to 33 are closed and the fourth valve 34 is open, the compressor 3 operates, and refrigerant is supplied to and stored in the receiver tank 7. As described above, the refrigerant stored in the receiver tank 7 can be used appropriately to lubricate the compressor 3 when the vehicle 200 is started.

[0045] The control device 50 opens the third valve 33 and closes the fourth valve 34 when the vehicle 200 is at time t5, and this time t5 is determined to be the timing when the pressure detected by the second pressure sensor 42 becomes equal to or greater than a predetermined value. In other words, when the pressure of the refrigerant stored in the receiver tank 7 becomes equal to or greater than a predetermined value, the control device 50 closes the fourth valve 34 and stops the supply of refrigerant to the receiver tank 7.

[0046] [Action and effect] Next, the operation and effects of the refrigerant circulation system 100 according to this embodiment will be described.

[0047] In this embodiment, the refrigerant circulation system 100 is mounted on a vehicle 200 and circulates a refrigerant containing oil in CO2. The refrigerant circulation system 100 includes a compressor 3 that compresses the refrigerant, a rotor 11 and a stator 12, a rotating shaft 13 connected to the rotor 11, and a plain bearing 14 that supports the rotating shaft 13. The motor 1 is configured to receive the refrigerant compressed by the compressor 3 and lubricate the plain bearing 14 using the refrigerant as a lubricant, and a refrigerant passage ( The vehicle 200 includes refrigerant passages (first passages) 16a to 16d, refrigerant passages (second passages) 17a and 17b for supplying refrigerant from the motor 1 to the compressor 3, a first valve 31 provided on the refrigerant passages 16a to 16d, and a second valve 32 provided on the refrigerant passages 17a and 17b, and a control device 50 configured to control the first valve 31, the second valve 32, and the compressor 3, and the control device 50 is configured to close the first valve 31 and the second valve 32 when the vehicle 200 is stopped.

[0048] In this embodiment, when the vehicle 200 is stopped, the first and second valves 31, 32, respectively provided upstream and downstream of the motor 1, are closed, thereby preventing the refrigerant from continuing to move within the refrigerant passage while the vehicle 200 is stopped; specifically, preventing the refrigerant from moving from the relatively high-pressure first passage to the relatively low-pressure second passage. As a result, when the vehicle 200 is started, the refrigerant oil in the first passage can be reliably supplied to the sliding bearing 14 of the motor 1, which means that a shortage of oil supply to the sliding bearing 14 can be prevented. Therefore, the refrigerant oil can adequately lubricate the sliding bearing 14 of the motor 1 during startup, preventing high friction, wear, seizure, and the like of the sliding bearing 14.

[0049] In addition, in this embodiment, the refrigerant circulation system 100 further includes a receiver tank 7 located downstream of the second valve 32 on the refrigerant passages 17a, 17b for storing the refrigerant compressed by the compressor 3, a refrigerant passage (third passage) 20 for supplying refrigerant from the upstream side of the first valve 31 on the refrigerant passages 16a to 16d to the receiver tank 7, a third valve 33 located downstream of the receiver tank 7 on the refrigerant passage 17b, and a fourth valve 34 located on the refrigerant passage 20, and the control device 50 is configured to operate the compressor 3 by closing the third valve 33 and opening the fourth valve 34 while keeping the first valve 31 and the second valve 32 closed when the vehicle 200 is stopped.

[0050] According to this embodiment, when the vehicle 200 is stopped, the refrigerant compressed by the compressor 3 can be stored in the receiver tank 7, and the refrigerant thus stored in the receiver tank 7 can be supplied to the compressor 3 when the vehicle 200 is started. This ensures that refrigerant oil is supplied to the compressor 3 when the vehicle 200 is started, that is, it is possible to prevent a shortage of oil supply to the compressor 3.

[0051] Furthermore, in this embodiment, when the vehicle 200 starts, the control device 50 is configured to operate the compressor 3, maintain the first valve 31 and the second valve 32 in a closed state for a predetermined time, and then open the first valve 31 and the second valve 32. As a result, by operating the compressor 3 with the first valve 31 and the second valve 32 closed immediately after the vehicle 200 starts, it is possible to reduce the pressure on the downstream side of the motor 1 below the pressure on the upstream side, and thereafter prevent backflow of the refrigerant when the first valve 31 and the second valve 32 are opened.

[0052] Furthermore, in this embodiment, when the vehicle 200 is stopped, the control device 50 is configured to operate the compressor 3 while keeping the first valve 31 and the second valve 32 open for a predetermined period of time, and then close the first valve 31 and the second valve 32. As a result, immediately after the vehicle 200 is stopped, the compressor 3 is operated with the first valve 31 and the second valve 32 open, and then the first valve 31 and the second valve 32 are closed, so that oil can be collected around the motor 1 when the vehicle 200 is stopped. The oil collected around the motor 1 in this way is supplied to the sliding bearing 14 when the vehicle 200 is started, making it possible to effectively prevent a shortage of oil supply to the sliding bearing 14.

[0053] Furthermore, in this embodiment, the refrigerant circulation system 100 includes refrigerant passage 16a for supplying the refrigerant to the sliding bearing 14 of the motor 1, as well as refrigerant passage 16b for supplying the refrigerant to the rotor 11 and stator 12 of the motor 1. This allows the refrigerant to be used both to lubricate and cool the motor 1, which makes it possible to simplify the system and reduce costs compared to systems that perform these functions separately. [Explanation of symbols]

[0054] 1 motor 3 Compressor 5 Heat exchanger 7. Receiver Tank 11 rotor 12 Stator 13 Rotation axis 14 Plain bearings 16a~16d Refrigerant passage (1st passage) 17a, 17b Refrigerant passage (2nd passage) 19 Expansion valve 20 Refrigerant passage (third passage) 31 First valve 32 Second valve 33 Third valve 34 4th valve 50 Control device 100 Refrigerant Circulation System 200 vehicles

Claims

1. It is installed in the vehicle and 2 A refrigerant circulation system that circulates a refrigerant containing oil, a compressor that compresses the refrigerant; a motor including a rotor and a stator, a rotating shaft connected to the rotor, and a sliding bearing supporting the rotating shaft, wherein the refrigerant compressed by the compressor is supplied and the sliding bearing uses the refrigerant as a lubricant for lubrication; a first passage for supplying the refrigerant from the compressor to the motor, and a second passage for supplying the refrigerant from the motor to the compressor; a first valve provided on the first passage and a second valve provided on the second passage; a controller configured to control the first valve, the second valve, and the compressor; and The control device is configured to close the first valve and the second valve when the vehicle stops. A refrigerant circulation system.

2. The refrigerant circulation system further comprises: a receiver tank provided on the second passage downstream of the second valve for storing the refrigerant compressed by the compressor; a third passage for supplying the refrigerant from the upstream side of the first valve on the first passage to the receiver tank; a third valve provided on the second passage downstream of the receiver tank, and a fourth valve provided on the third passage; and the control device is configured to operate the compressor by closing the third valve and opening the fourth valve while keeping the first valve and the second valve closed when the vehicle is stopped. The refrigerant circulation system of claim 1 .

3. 2. The refrigerant circulation system according to claim 1, wherein the control device is configured to operate the compressor when the vehicle is started, and to maintain the first valve and the second valve in a closed state for a predetermined time, and then open the first valve and the second valve.

4. 2. The refrigerant circulation system according to claim 1, wherein the control device is configured to operate the compressor while maintaining the first valve and the second valve in an open state for a predetermined time, and then close the first valve and the second valve when the vehicle is stopped.

5. 2. The refrigerant circulation system according to claim 1, wherein the first passage includes a passage for supplying the refrigerant to the rotor or the stator of the motor in addition to a passage for supplying the refrigerant to the sliding bearing of the motor.

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