Refrigerant circulation system

Abstract

To reduce stirring resistance generated in a motor in a refrigerant circulation system for cooling and lubricating the motor by circulating a refrigerant containing oil.SOLUTION: A refrigerant circulating system 100 includes a motor 4 including a rotor 41, a stator 42, a rotating shaft 43, and a plain bearing 44, a gas-liquid separator 12 that separates a refrigerant into CO2 and oil, a CO2 path 22b that supplies the CO2 separated by the gas-liquid separator between the rotor and the stator to cool the rotor and the stator, and a mixing unit that mixes the CO2 and the oil separated by the gas-liquid separator and supplies a mixture of the CO2 and the oil between the rotating shaft and the plain bearing. The compressor has a mixture path 24a for lubricating the plain bearing, and a mixture path 24b for returning the CO2 supplied from the CO2 path 22b to the rotor and the stator, and the mixture of the CO2 and the oil supplied from the mixture path 24a to the plain bearing 44 to the gas-liquid separator.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a refrigerant circulation system that circulates an oil-containing refrigerant. [Background technology]

[0002] Conventionally, a system (refrigerant circulation system) that circulates a refrigerant via a compressor, a heat exchanger, etc. has been used in a refrigeration cycle used in an air conditioner, etc. In recent years, such a refrigerant circulation system has also been used to cool and heat various components (e.g., a motor, a battery, etc.) inside a vehicle.

[0003] In this type of refrigerant circulation system, a refrigerant containing oil (refrigeration oil) is generally used to lubricate and seal various components, and this oil also circulates within the system. For example, Patent Document 1 describes a system that uses an oil-containing refrigerant to cool the rotor and stator of the motor of an electric compressor, as well as to lubricate and cool the rotating shaft and bearings of the motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-960 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, technologies that use natural refrigerants in refrigeration cycles have been developed with consideration for the environment, etc. When using such natural refrigerants to cool vehicle motors, etc., it is desirable for the natural refrigerants to have insulating properties, so a method of using a refrigerant containing CO2 (specifically, a refrigerant in which oil or the like is mixed with CO2, hereinafter referred to as "CO2 refrigerant") is considered.

[0006] The technology described in Patent Document 1 uses a refrigerant (such as a CO2 refrigerant) to cool the rotor and stator of a motor and lubricate the motor's bearings. However, this technology has the following problems. First, in the technology described in Patent Document 1, the refrigerant contains oil (lubricant), which is effective in lubricating the motor's bearings. However, when the motor's rotor and stator are cooled with a refrigerant, the oil in the refrigerant generates agitation resistance between the rotor and stator. Specifically, when the refrigerant passes between the rotor and stator, a large shear resistance occurs due to the viscosity of the oil in the refrigerant, which increases the agitation resistance. This agitation resistance reduces the torque output from the motor.

[0007] The present invention has been made to solve the problems of the conventional technology described above, and aims to reduce the stirring resistance generated by the refrigerant inside a motor in a refrigerant circulation system that circulates an oil-containing refrigerant to cool and lubricate the motor. [Means for solving the problem]

[0008] 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 containing oil in CO2, and is characterized by having: a motor for driving the vehicle, including a rotor and a stator, a rotating shaft connected to the rotor, and a sliding bearing supporting the rotating shaft; a gas-liquid separator that separates the refrigerant into gaseous CO2 and oil; a first passage for supplying the CO2 separated by the gas-liquid separator between the rotor and stator of the motor to cool the rotor and / or the stator; a second passage for mixing the CO2 separated by the gas-liquid separator with the oil and supplying this mixture of CO2 and oil between the rotating shaft of the motor and the sliding bearing to lubricate the sliding bearing; and a third passage for returning the CO2 supplied from the first passage to the rotor and stator, and the mixture of CO2 and oil supplied from the second passage to the sliding bearing, to the gas-liquid separator.

[0009] In the present invention configured in this manner, a mixture of CO2 and oil is supplied to the sliding bearing of the motor, while only CO2 is supplied to the rotor and stator of the motor. In other words, according to the present invention, a refrigerant (mixture) containing oil, i.e., a refrigerant with a certain degree of viscosity, is supplied to the sliding bearing, while a refrigerant not containing oil (basically just CO2), i.e., a refrigerant with a low viscosity, is supplied to the rotor and stator. Therefore, according to the present invention, it is possible to reduce the stirring resistance generated by the refrigerant between the rotor and stator while ensuring lubrication in the sliding bearing.

[0010] In the present invention, preferably, the motor further includes a housing that accommodates the rotor, the stator, the rotating shaft, and the sliding bearing, and a sealing member that uses oil to seal the gap between the rotating shaft and the housing, and the refrigerant circulation system further includes a fourth passage that supplies the oil separated by the gas-liquid separator to the sealing member of the motor. According to the present invention configured in this manner, as described above, it is possible to ensure the lubrication of the sliding bearing and reduce the stirring resistance that occurs between the rotor and stator, while also ensuring the sealing performance of the sealing member.

[0011] In the present invention, preferably, a plurality of grooves extending in the circumferential direction are formed on the outer peripheral surface of the rotor or the inner peripheral surface of the stator for diffusing CO2 into the gap between the rotor and the stator. As described above, supplying CO2 to the rotor and stator can reduce stirring resistance, but CO2 has low viscosity, making it difficult for CO2 to penetrate the entire gap between the rotor and stator. To address this issue, the present invention provides multiple grooves on the outer circumferential surface of the rotor. These multiple grooves can promote the flow of CO2 in the gap between the rotor and stator, allowing CO2 to penetrate the entire gap between the rotor and stator.

[0012] In the present invention, each of the plurality of grooves is preferably formed so that a portion on the opposite side to the direction of rotation of the rotor is deeper than a portion on the side in the direction of rotation of the rotor. According to the present invention configured in this way, CO2 can be drawn into the groove from the shallow portion of the groove on the rotational direction side (i.e., the leading end of the groove), and the CO2 drawn into the groove can be forcefully discharged from the deep portion of the groove on the opposite side of the rotational direction (i.e., the trailing end of the groove). Thus, according to the present invention, the flow of CO2 in the gap between the rotor and the stator can be effectively promoted.

[0013] In the present invention, the first passage is preferably configured to supply CO2 to the axial central portion of the rotor and the stator, and each of the plurality of grooves is formed to be inclined so as to move away from the axial central portion as it progresses in the direction opposite to the rotational direction of the rotor. The grooves formed to be inclined in this manner can generate a flow of CO2 that includes components in the circumferential direction and the axial direction (particularly in the axial direction toward the end side of the rotor). Therefore, according to the present invention, CO2 supplied to the axial central portion from the first passage can be appropriately directed toward the axial end sides of the rotor and stator, making it possible to effectively distribute CO2 throughout the entire gap between the rotor and stator.

[0014] In the present invention, preferably, the refrigerant circulation system further includes a mixer configured to increase the proportion of oil in the mixture as the rotation speed of the motor decreases, and to increase the proportion of CO2 in the mixture as the rotation speed of the motor increases. According to the present invention configured in this manner, the viscosity of the mixture applied to the sliding bearing can be changed in accordance with the rotation speed of the motor, making it possible to achieve the desired load capacity in the sliding bearing.

[0015] In the present invention, preferably, the refrigerant circulation system further includes an air conditioner that performs air conditioning using a refrigerant, a battery that supplies power to drive the motor, a fifth passage for supplying CO2 separated by the gas-liquid separator to the air conditioner, a sixth passage for supplying CO2 separated by the gas-liquid separator to the battery, and a multi-way valve configured to be able to switch the passage for supplying CO2 separated by the gas-liquid separator to at least one of the first, second, fifth and sixth passages. According to the present invention configured in this manner, by using a multi-way valve to switch the path through which CO2 is supplied, the refrigerant circulation system, which uses refrigerant for cooling, can be shared appropriately between the motor, air conditioner, and battery. [Effects of the Invention]

[0016] According to the present invention, in a refrigerant circulation system that circulates an oil-containing refrigerant to cool and lubricate a motor, it is possible to reduce the stirring resistance generated by the refrigerant within the motor. [Brief explanation of the drawings]

[0017] [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 refrigerant circulation system according to an embodiment of the present invention. [Figure 3] 1 is a schematic configuration diagram of a motor according to an embodiment of the present invention. [Figure 4] 1 is a schematic perspective view of a rotor of a motor according to an embodiment of the present invention; [Figure 5] 5 is a schematic cross-sectional view of a rotor according to an embodiment of the present invention, taken along line VV in FIG. 4. [Figure 6] FIG. 2 is an enlarged perspective view of a groove in a rotor according to an embodiment of the present invention. [Figure 7] FIG. 10 is an illustration of the flow of CO2 through grooves in a rotor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a refrigerant circulation system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0019] [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.

[0020] 1, vehicle 200 is, for example, an electric vehicle, and includes a refrigerant circulation system 100 that circulates a refrigerant in a refrigeration cycle. This refrigerant circulation system 100 mainly includes a compressor 1 for compressing the refrigerant, a heat exchanger 2 for cooling the refrigerant compressed by compressor 1, a motor 4 for generating power to drive vehicle 200, an air conditioner 5 for conditioning the interior of vehicle 200, and a battery 6 for supplying power to drive motor 4.

[0021] The refrigerant circulation system 100 circulates a CO2 refrigerant (hereinafter sometimes simply referred to as "refrigerant") as a natural refrigerant. This CO2 refrigerant is a refrigerant containing refrigeration oil (oil) such as PAG and additives. To use this CO2 refrigerant, the compressor 1 is configured to compress the refrigerant to extremely high pressures. The motor 4 uses the refrigerant (typically in a supercritical state) compressed by the compressor 1 to lubricate the sliding bearings that support the rotating shaft and to cool the rotor and stator. In this case, the motor 4 is configured to function as an evaporator in the refrigeration cycle. The refrigerant compressed by the compressor 1 is used for air conditioning in the air conditioner 5 and for cooling the battery 6. For example, in the refrigerant circulation system 100, high-temperature, high-pressure gas refrigerant is supplied from the compressor 1 to the heat exchanger 2, low-temperature, high-pressure liquid refrigerant is supplied from the heat exchanger 2 to the motor 4, and room-temperature, low-pressure gas refrigerant is supplied from the motor 4 to the compressor 1.

[0022] [Configuration of refrigerant circulation system] Next, the refrigerant circulation system 100 according to this embodiment will be specifically described with reference to Fig. 2. Fig. 2 is a schematic diagram of the refrigerant circulation system 100 according to this embodiment.

[0023] As shown in FIG. 2, the refrigerant circulation system 100 mainly includes, in addition to the compressor 1, heat exchanger 2, motor 4, air conditioner 5, and battery 6 described above, a gas-liquid separator 12 for separating the refrigerant into CO2 and oil, a CO2 tank 13 and an oil tank 14 for storing the CO2 and oil separated by the gas-liquid separator 12, respectively, a mixer 15 for mixing the CO2 and oil, and a storage tank for storing the CO2 (including a small amount of oil) separated by the gas-liquid separator 12. The same applies below.) passes through CO2 passages 21a-21f, 22a-22e, 25a-25d, oil passages 23a-23d through which oil separated by gas-liquid separator 12 passes, mixture passages 24a and 24b through which a mixture of CO2 and oil passes, multi-way valves V1-V4 that can switch the passages for supplying CO2 and oil, expansion valve E1 for expanding CO2 to be supplied to motor 4, and expansion valve E2 for expanding CO2 to be supplied to battery 6. CO2 passages 21a-21f (shown by dashed lines in FIG. 1) are passages through which CO2 flows for temperature increase (heating), and CO2 passages 22a-22e (shown by solid lines (thin lines) in FIG. 1) are passages through which CO2 flows for cooling.

[0024] The compressor 1 is supplied with CO2 via a CO2 passage 25d, specifically CO2 stored in a CO2 tank 13, and compresses the CO2 to supply it to a multi-way valve V1 via a CO2 passage 21a. The multi-way valve (3-way valve) V1 is configured to be able to select at least one of supplying CO2 to the heat exchanger 2 via a CO2 passage 21b and supplying CO2 to the multi-way valve V2 via a CO2 passage 21c. The multi-way valve (4-way valve) V2 is configured to be able to select at least one of supplying CO2 to the mixer 15 via a CO2 passage 21d, supplying CO2 to the air conditioner 5 via a CO2 passage 21e, and supplying CO2 to the battery 6 via a CO2 passage 21f. In this case, the air conditioner 5 functions as a heater using the supplied CO2, and the battery 6 is heated by the supplied CO2.

[0025] Next, the heat exchanger 2 receives CO2 from the multi-way valve V1 via a CO2 passage 21b, cools the CO2 by exchanging heat with the outside air, and supplies the CO2 to the multi-way valve V3 via a CO2 passage 22a. The multi-way valve (five-way valve) V3 is configured to select at least one of the following: supplying CO2 to the rotor 41 and stator 42 of the motor 4 via a CO2 passage 22b; supplying CO2 to the mixer 15 via a CO2 passage 22c; supplying CO2 to the air conditioner 5 via a CO2 passage 22d; and supplying CO2 to the battery 6 via a CO2 passage 22e. In this case, the rotor 41 and stator 42 of the motor 4 are cooled by the supplied CO2, the air conditioner 5 functions as a cooler using the supplied CO2, and the battery 6 is cooled by the supplied CO2. In addition, CO2 is supplied to the rotor 41 and stator 42 of the motor 4 via the expansion valve E1, i.e., CO2 decompressed by the expansion valve E1 is supplied, and CO2 is supplied to the battery 6 via the expansion valve E2, i.e., CO2 decompressed by the expansion valve E2 is supplied.

[0026] Meanwhile, oil stored in the oil tank 14 is supplied to the multi-way valve V4 via oil passage 23b. In this case, the oil is pumped by an oil pump P1 on the oil passage 23b. The multi-way valve (three-way valve) V4 is configured to be able to select at least one of supplying oil to the mixer 15 via oil passage 23c and supplying oil to the seal member 46 of the motor 4 via oil passage 23d. The mixer 15 mixes the CO2 supplied from the CO2 passages 21d and 22c with the oil supplied from the oil passage 23c, and supplies the mixture of CO2 and oil to the sliding bearing 44 of the motor 4 via mixture passage 24a. The mixer 15 is configured so that the mixture ratio of CO2 and oil can be changed by a control device (not shown).

[0027] The configuration of the motor 4 according to this embodiment will now be described in detail with reference to Fig. 3. Fig. 3 is a schematic diagram of the motor 4 according to this embodiment. Specifically, Fig. 3 is a cross-sectional view of the motor 4 as viewed along the axial direction.

[0028] As shown in Figure 3, the motor 4 mainly has a rotor 41, a stator 42, a rotating shaft 43 connected to the rotor 41 and one end of which is connected to a transaxle (not shown) of the vehicle 200, a pair of plain bearings 44 (44a, 44b) that support the rotating shaft 43, and a housing 45 that accommodates the rotor 41, the stator 42, the rotating shaft 43, the plain bearing 44, etc.

[0029] As described above, in the motor 4, CO2 is supplied from the CO2 passage 22b to the rotor 41 and the stator 42. Specifically, CO2 from the CO2 passage 22b is supplied to the axial central portions of the rotor 41 and the stator 42, and this CO2 is distributed throughout the entire gap between the rotor 41 and the stator 42. The CO2 supplied in this manner is used to cool the rotor 41 and the stator 42, and in particular to cool the coil (not shown) inside the stator 42. In this case, the CO2 exchanges heat with the stator 42, which is relatively hot (at which time the refrigerant evaporates in the coil of the stator 42), thereby realizing the function of an evaporator in a refrigeration cycle.

[0030] In the motor 4, a mixture of CO2 and oil is supplied from the mixture passage 24a to each of the pair of plain bearings 44; more specifically, the mixture is supplied to the gap between the rotating shaft 43 and the plain bearing 44. The plain bearing 44 is configured to be lubricated using the mixture thus supplied as a lubricant. In this case, the plain bearing 44 is lubricated using a liquid mixture (typically a refrigerant containing CO2 in a supercritical state).

[0031] Motor 4 also has a seal member 46 for sealing the side of rotating shaft 43 connected to a transaxle or the like (the side where plain bearing 44a is provided). This seal member 46 is provided to prevent refrigerant leakage from a gap between housing 45 and the part of rotating shaft 43 extending outward from housing 45. As described above, seal member 46 is configured as a mechanical seal that receives oil from oil passage 23d and uses this oil to prevent refrigerant leakage.

[0032] The CO2 used for cooling the rotor 41 and stator 42, the mixture used for lubrication in the sliding bearing 44, and the oil used for sealing in the seal member 46 all flow out of the mixture passage 24b and are returned to the gas-liquid separator 12 (Figure 1).

[0033] If a rolling bearing is applied to the motor 4, in an electric vehicle, the rotating shaft 43 of the motor 4 rotates at a high rotation speed of, for example, over 30,000 rpm, and this causes 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 4, the loss of oil agitation resistance caused by the rotating shaft 43 becomes large. Therefore, in this embodiment, a sliding bearing 44 that uses a refrigerant (mixture) that is made liquid (supercritical state) by compression by the compressor 1 is applied to the motor 4. This makes it possible to solve problems such as rolling fatigue and oil agitation resistance.

[0034] Furthermore, in this embodiment, when a mixture of CO2 and oil is used in the sliding bearing 44 in this way, the mixture ratio of these CO2 and oil is changed according to the motor rotation speed (which corresponds to the rotation speed of the rotating shaft 43 of the motor 4). This adjustment of the mixture ratio is achieved by control of the mixer 15 by the control device. Specifically, in this embodiment, the lower the motor rotation speed, the lower the load capacity of the sliding bearing 44, so the proportion of oil in the mixture is increased to ensure the desired load capacity (i.e., to increase the viscosity of the mixture). On the other hand, as the motor rotation speed increases, the load capacity of the sliding bearing 44 is ensured due to the wedge effect and throttle effect, so it is not necessary to use as much oil in the mixture (i.e., it is not necessary to increase the viscosity of the mixture), and so the proportion of oil in the mixture is reduced, that is, the proportion of CO2 in the mixture is increased.

[0035] Returning to FIG. 2, the gas-liquid separator 12 receives a mixture of CO2 and oil from the motor 4 via the mixture passage 24b and separates the mixture into CO2 and oil (gas-oil separation). The gas-liquid separator 12 then supplies the separated oil to the oil tank 14 via the oil passage 23a. The gas-liquid separator 12 also supplies the separated CO2 to the CO2 tank 13 via a CO2 passage 25a. CO2 is also supplied to the CO2 tank 13 from the air conditioner 5 and the battery 6 via CO2 passages 25b and 25c, respectively.

[0036] The CO2 passage 22b corresponds to the "first passage" in the present invention, the mixture passage 24a corresponds to the "second passage" in the present invention, the mixture passage 24b corresponds to the "third passage" in the present invention, the oil passage 23d corresponds to the "fourth passage" in the present invention, the CO2 passages 21e and 22d correspond to the "fifth passage" in the present invention, and the CO2 passages 21f and 22e correspond to the "sixth passage" in the present invention.

[0037] [Rotor configuration] Next, the configuration of the rotor 41 of the motor 4 according to this embodiment will be described with reference to Figures 4 to 7. Figure 4 shows a schematic perspective view of the rotor 41, Figure 5 shows a schematic cross-sectional view of the rotor 41 taken along line VV in Figure 4, Figure 6 shows an enlarged perspective view of the grooves 41a of the rotor 41, and Figure 7 is an explanatory diagram of the flow of CO2 through the grooves 41a of the rotor 41. Note that Figure 7 shows a schematic plan view of some of the multiple grooves 41a.

[0038] As shown in FIG. 4 , in this embodiment, a plurality of grooves 41a extending along the circumferential direction of the rotor 41 are formed on the outer peripheral surface of the rotor 41 of the motor 4. Before describing the specific configuration of the grooves 41a, the reason for providing the grooves 41a on the rotor 41 in this embodiment will be explained. The CO2 supplied from the CO2 passage 22b to the gap between the rotor 41 and the stator 42 contains almost no oil (because the oil is separated by the gas-liquid separator 12). Therefore, the viscosity is low, which reduces the stirring resistance between the rotor 41 and the stator 42. However, due to the low viscosity, it is difficult for the CO2 to spread throughout the entire gap between the rotor 41 and the stator 42. This is particularly true when the amount of CO2 being supplied is small. Therefore, in this embodiment, a plurality of grooves 41a are provided on the outer peripheral surface of the rotor 41 to diffuse the CO2 throughout the entire gap between the rotor 41 and the stator 42.

[0039] Next, a specific configuration of the grooves 41a according to this embodiment will be described. As shown in Fig. 4, the grooves 41a are arranged symmetrically (left-right symmetry) around the axial center portion of the rotor 41 (the portion to which CO2 is supplied from the CO2 passage 22b). The grooves 41a located on the left and right sides of this center portion are arranged at equal intervals in the axial and circumferential directions. Furthermore, each of the grooves 41a is formed so as to incline so as to move away from the axial center portion as it moves in the direction opposite to the rotation direction of the rotor 41. When viewed as a whole, the grooves 41a provided in the rotor 41 in this way form a V-shape that is symmetrical around the center portion of the rotor 41.

[0040] 5 and 6, each of the plurality of grooves 41a is formed so that the depth of the portion opposite the rotation direction of the rotor 41 (region R2 in FIG. 6) is greater than the depth of the portion toward the rotation direction of the rotor 41 (region R1 in FIG. 6). For example, the groove 41a is formed so that its maximum depth (the depth of region R2) is approximately the same as the clearance between the rotor 41 and the stator 42. The plurality of grooves 41a are provided at positions corresponding to each of a plurality of pairs of electromagnetic steel plates 41b provided at equal intervals along the circumferential direction inside the rotor 41 (inside near the outer circumferential surface) (FIG. 5). In particular, the grooves 41a are provided at positions that do not adversely affect the strength of the electromagnetic steel plates 41b or the electromagnetic field formation (electromagnetic performance).

[0041] Next, the flow of CO2 through the multiple grooves 41a will be specifically described. According to the grooves 41a of this embodiment, CO2 is first drawn into the grooves 41a from shallow portions of the grooves 41a on the rotational direction side (i.e., the leading-side ends of the grooves 41a) (arrow A21 in FIG. 6 ), and then flows through the grooves 41a (arrow A22 in FIG. 6 ). Then, the CO2 in the grooves 41a flows outward with force from deep portions of the grooves 41a on the opposite side of the rotational direction (i.e., the trailing-side ends of the grooves 41a) (arrow A23 in FIG. 6 ). In this case, a flow of CO2 occurs radially outward from the rotor 41 (arrow A1 in FIG. 5 ).

[0042] As described above, the groove 41a according to this embodiment can generate a flow of CO2 that includes components in the circumferential direction and the axial direction (particularly the axial direction toward the end of the rotor 41), as indicated by arrow A3 in Fig. 7. This allows CO2 to spread throughout the entire gap between the rotor 41 and the stator 42. In this case, CO2 supplied from the CO2 passage 22b to the central portion in the axial direction can be appropriately spread toward the end of the rotor 41 in the axial direction.

[0043] According to tests conducted by the present inventors, it was found that when grooves having a uniform depth in the circumferential direction and a substantially rectangular shape in cross section are used, local vortices are generated within the grooves, making it impossible to distribute CO2 as in the present embodiment. Also, it was found that when grooves having an arc-shaped bottom in cross section, with the same depth on both the rotational direction and the opposite side in the circumferential direction, are used, CO2 slips through the grooves, making it impossible to distribute CO2 as in the present embodiment.

[0044] [Action and effect] Next, the operation and effects of the refrigerant circulation system 100 according to this embodiment will be described. The refrigerant circulation system 100 according to this embodiment includes a motor 4 for driving a vehicle 200, the motor 4 including a rotor 41 and a stator 42, a rotating shaft 43 connected to the rotor 41, and a plain bearing 44 supporting the rotating shaft 43, a gas-liquid separator 12 for separating the refrigerant into gaseous CO2 and oil, a CO2 passage 22b for supplying the CO2 separated by the gas-liquid separator 12 between the rotor 41 and the stator 42 of the motor 4 to cool the rotor 41 and the stator 42, a mixture passage 24a for mixing the CO2 separated by the gas-liquid separator 12 with the oil and supplying the mixture of CO2 and oil between the rotating shaft 43 of the motor 4 and the plain bearing 44 to lubricate the plain bearing 44, and a mixture passage 24b for returning the CO2 supplied from the CO2 passage 22b to the rotor 41 and the stator 42 and the mixture of CO2 and oil supplied from the mixture passage 24a to the plain bearing 44 to the gas-liquid separator 12.

[0045] In this embodiment, a mixture of CO2 and oil is supplied to the sliding bearing 44 of the motor 4, while only CO2 is supplied to the rotor 41 and stator 42 of the motor 4. That is, according to this embodiment, a refrigerant (mixture) containing oil, i.e., a refrigerant with a certain degree of viscosity, is supplied to the sliding bearing 44, while a refrigerant not containing oil (basically only CO2), i.e., a refrigerant with a low viscosity, is supplied to the rotor 41 and stator 42. Therefore, according to this embodiment, it is possible to reduce the stirring resistance generated between the rotor 41 and stator 42 while ensuring lubrication in the sliding bearing 44.

[0046] Furthermore, according to the present embodiment, the motor 4 further includes a housing 45 that accommodates the rotor 41, the stator 42, the rotating shaft 43, and the sliding bearing 44, and a sealing member 46 that uses oil to seal the gap between the rotating shaft 43 and the housing 45, and the refrigerant circulation system 100 further includes an oil passage 23d that supplies the oil separated by the gas-liquid separator 12 to the sealing member 46 of the motor 4. This ensures the lubrication of the sliding bearing 44 and reduces the stirring resistance that occurs between the rotor 41 and the stator 42, while also ensuring the sealing performance of the sealing member 46.

[0047] Furthermore, according to this embodiment, the outer peripheral surface of the rotor 41 is formed with a plurality of grooves 41a extending in the circumferential direction for diffusing CO2 in the gap between the rotor 41 and the stator 42. As described above, supplying CO2 to the rotor 41 and the stator 42 can reduce stirring resistance, but CO2 has a low viscosity, making it difficult for CO2 to spread throughout the entire gap between the rotor 41 and the stator 42. To address this issue, in this embodiment, a plurality of grooves 41a are provided on the outer peripheral surface of the rotor 41. These grooves 41a can promote the flow of CO2 in the gap between the rotor 41 and the stator 42, allowing CO2 to spread throughout the entire gap between the rotor 41 and the stator 42.

[0048] Furthermore, according to this embodiment, each of the plurality of grooves 41a is formed so that the portion opposite the rotation direction of the rotor 41 is deeper than the portion toward the rotation direction of the rotor 41. This allows CO2 to be drawn into the groove 41a from the shallow portion of the groove 41a toward the rotation direction (i.e., the leading end of the groove 41a). The CO2 drawn into the groove 41a can then be forcefully discharged from the deep portion of the groove 41a toward the rotation direction (i.e., the trailing end of the groove 41a). Therefore, according to this embodiment, the flow of CO2 in the gap between the rotor 41 and the stator 42 can be effectively promoted.

[0049] Furthermore, according to this embodiment, the CO2 passage 22b is configured to supply CO2 to the axial central portions of the rotor 41 and the stator 42, and each of the multiple grooves 41a is formed to be inclined so as to move away from the axial central portion as it progresses in the opposite direction to the rotational direction of the rotor 41. The inclined grooves 41a in this manner can generate a flow of CO2 that includes components in the circumferential direction and the axial direction (particularly the axial direction toward the end side of the rotor 41). Therefore, according to this embodiment, CO2 supplied to the axial central portion from the CO2 passage 22b can be appropriately flowed toward the axial end sides of the rotor 41 and the stator 42, making it possible to effectively distribute CO2 throughout the entire gap between the rotor 41 and the stator 42.

[0050] Furthermore, according to the present embodiment, the refrigerant circulation system 100 further includes a mixer 15 configured so that the lower the motor rotation speed, the greater the proportion of oil in the mixture, and the higher the motor rotation speed, the greater the proportion of CO2 in the mixture. This makes it possible to change the viscosity of the mixture applied to the sliding bearing 44 in accordance with the motor rotation speed, making it possible to achieve a desired load capacity in the sliding bearing 44 (typically, it becomes possible to achieve a constant load capacity regardless of the motor rotation speed).

[0051] According to this embodiment, the refrigerant circulation system 100 further includes an air conditioner 5 that performs air conditioning using a refrigerant, a battery 6 that supplies power to drive the motor 4, a CO2 passage 22d for supplying CO2 separated by the gas-liquid separator 12 to the air conditioner 5, a CO2 passage 22e for supplying CO2 separated by the gas-liquid separator 12 to the battery 6, and a multi-way valve V3 configured to switch the passage for supplying CO2 separated by the gas-liquid separator 12 to at least one of CO2 passage 22b, CO2 passage 22c, CO2 passage 22d, and CO2 passage 22e. According to this embodiment, by using the multi-way valve V3 to switch the passage for supplying CO2, the refrigerant circulation system 100 that performs cooling using a refrigerant can be appropriately shared among the motor 4, the air conditioner 5, and the battery 6.

[0052] [Variations] In the above-described embodiment, the plurality of grooves 41a are provided on the outer peripheral surface of the rotor 41, but in a modified example, the plurality of grooves 41a may be provided on the inner peripheral surface of the stator 42. The plurality of grooves 41a provided on the stator 42 in this manner can also promote the flow of CO2 in the gap between the rotor 41 and the stator 42, making it possible for CO2 to spread throughout the entire gap between the rotor 41 and the stator 42. [Explanation of symbols]

[0053] 1 Compressor 2 Heat exchanger 4 motors 5. Air Conditioning 6 Battery 12 Gas-liquid separator 15 Mixer 21a~21f, 22a~22e, 25a~25d CO2 passage 23a~23d Oil passages 24a, 24b Mixture passage 41 Rotor 41a Groove 41b Electrical steel sheet 42 Stator 43 Rotation axis 44 Plain bearing 45 Housing 46 Sealing material 100 Refrigerant Circulation System 200 vehicles E1, E2 expansion valve V1, V2, V3, V4 multi-way valve

Claims

1. It is installed in the vehicle and 2 A refrigerant circulation system that circulates a refrigerant containing oil in a a motor for driving the vehicle, the motor including a rotor, a stator, a rotating shaft connected to the rotor, and a sliding bearing supporting the rotating shaft; The refrigerant is CO as a gas. 2 a gas-liquid separator for separating the gas and oil; The CO separated by the gas-liquid separator 2 a first passage for supplying the cooling fluid between the rotor and the stator of the motor to cool the rotor and / or the stator; The CO separated by the gas-liquid separator 2 and the oil, and 2 a second passage for supplying a mixture of the lubricant and oil between the rotating shaft of the motor and the sliding bearing to lubricate the sliding bearing; The CO supplied from the first passage to the rotor and the stator 2 and the CO supplied from the second passage to the sliding bearing. 2 a third passage for returning the mixture of the oil and the mixture to the gas-liquid separator; A refrigerant circulation system comprising:

2. the motor further includes a housing that accommodates the rotor, the stator, the rotating shaft, and the sliding bearing, and a seal member that uses the oil to seal a gap between the rotating shaft and the housing, the refrigerant circulation system further includes a fourth passage for supplying the oil separated by the gas-liquid separator to the seal member of the motor. The refrigerant circulation system of claim 1 .

3. The CO is disposed in a gap between the rotor and the stator on the outer peripheral surface of the rotor or the inner peripheral surface of the stator. 2 The refrigerant circulation system according to claim 1 , further comprising a plurality of grooves extending in a circumferential direction for diffusing the refrigerant.

4. The refrigerant circulation system according to claim 3 , wherein each of the plurality of grooves is formed so that a portion opposite to a rotation direction of the rotor is deeper than a portion in the rotation direction of the rotor.

5. The first passage is provided at the center of the rotor and the stator in the axial direction. 2 configured to provide Each of the plurality of grooves is formed to be inclined so as to move away from the central portion in the axial direction as it progresses in a direction opposite to a rotation direction of the rotor.

5. The refrigerant circulation system according to claim 3 or 4.

6. In the refrigerant circulation system, the ratio of the oil in the mixture increases as the rotation speed of the motor decreases, and the ratio of the CO in the mixture decreases as the rotation speed of the motor increases. 2 The refrigerant circulation system according to claim 1 , further comprising a mixer configured to increase the ratio of

7. The refrigerant circulation system includes: an air conditioner that performs air conditioning using the refrigerant; a battery that supplies power to drive the motor; The CO separated by the gas-liquid separator 2 a fifth passage for supplying the air conditioner with The CO separated by the gas-liquid separator 2 a sixth passage for supplying the battery with The CO separated by the gas-liquid separator 2 a multi-way valve configured to be able to switch a passage for supplying the The refrigerant circulation system according to claim 1 , further comprising:

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