Coolant circulation system

Abstract

To provide a coolant circulation system to lubricant a slide bearing of a motor with a coolant, in which sludge of oil at a sealing member and burning of a sliding surface are prevented.SOLUTION: A coolant circulation system 100 to circulate a coolant including CO2 includes: a motor 1 including a slide bearing 14 that lubricates using a liquid coolant compressed with a compressor 3 and supports a rotary shaft 13; and a sealing member 18 including a rotary ring 51 that is attached to an outer periphery of the rotary shaft and rotates together with the rotary shaft, and a fixed ring 58 that is fixed to a housing 15, provided adjacent to the rotary ring in an axial direction so as to slide with the rotary ring, and preventing the leak of the coolant from a gap between the rotary shaft and the housing. In the rotary shaft, an oil passage 27a extending in the rotary shaft and letting oil flow therein is formed. In the rotary ring, an oil passage 27b that supplies the oil from the oil passage 27a to a gap between the rotary ring and the fixed ring is formed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Conventionally, refrigerant circulation systems have been used in refrigeration cycles used in air conditioners, in which a refrigerant is circulated through a compressor, a heat exchanger, etc. In recent years, such refrigerant circulation systems have also been used to cool components inside vehicles, for example, the batteries of electric vehicles and hybrid vehicles. As one example, Patent Document 1 discloses a vehicle that shares a single compressor and supplies the refrigerant flowing out from the compressor to the air conditioner and battery, thereby achieving a smaller and less expensive system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-037294 Summary of the Invention [Problem to be solved by the invention]

[0004] 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 motor's rotating shaft rotates at high speeds of, for example, over 30,000 rpm, which can lead to problems with rolling fatigue and reduced 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 becomes significant.

[0005] 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 - in particular a CO2 refrigerant that is liquefied when compressed by a compressor.At the same time, the present inventors also considered having this motor perform part of the function of the refrigeration cycle of the refrigerant circulation system, specifically functioning as an expansion valve or evaporator in the refrigeration cycle.

[0006] Here, when lubricating a sliding bearing with a high-pressure refrigerant (CO refrigerant) compressed by a compressor as described above, it is necessary to prevent this high-pressure refrigerant (for example, about 10 MPa) from leaking from the gap between the rotating shaft and the housing of the motor. A mechanical seal (sealing member) is generally used to seal the gap between the rotating shaft and the housing of a motor. This sealing member has a rotating ring that rotates with the rotating shaft and a fixed ring that is fixed to the housing and slides against the rotating ring, and the rotating ring and fixed ring seal the gap between the rotating shaft and the housing. Typically, oil (lubricating oil) is applied to the sliding surfaces of the rotating ring and the fixed ring, allowing them to slide against each other via this oil.

[0007] When attempting to prevent leakage of the refrigerant used in the sliding bearing described above using such a sealing member, it is necessary to increase the surface pressure on the sliding surfaces between the rotating ring and the fixed ring because the refrigerant is at high pressure. However, increasing the surface pressure on the sliding surfaces can cause the sliding surfaces to heat up due to friction, which can lead to oil sludge and seizure on the sliding surfaces. In particular, in electric vehicles, the motors operate at high rotation speeds, which increases the likelihood of such sludge and seizure. The reasons for this include the inability to form a sufficient oil film at the interface due to the high surface pressure on the sliding surfaces, and the inability to maintain a low sliding surface temperature because the oil receives heat from the sliding surfaces.

[0008] The present invention has been made to solve the problems of the conventional technology described above, and has an object to prevent oil sludge on sealing members and seizure of sliding surfaces in a refrigerant circulation system in which the sliding bearings of a motor are lubricated with a refrigerant and refrigerant leakage is prevented by sealing members. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a refrigerant circulation system that circulates a refrigerant containing CO2, comprising: a motor including a compressor that compresses the refrigerant, a rotor and a stator, a rotating shaft connected to the rotor, a housing that accommodates the rotor, the stator, and the rotating shaft, and a sliding bearing that supports the rotating shaft and is lubricated using liquid refrigerant compressed by the compressor; and a sealing member for preventing refrigerant leakage from a gap between the housing and a part of the rotating shaft extending to the outside, the sealing member including a rotating ring attached to the outer periphery of the rotating shaft and rotating together with the rotating shaft, and a fixed ring fixed to the housing and provided axially adjacent to the rotating ring so as to slide on the rotating ring, the sealing member being configured to seal the gap with the rotating ring and the fixed ring; the rotating shaft having a first passage extending into the rotating shaft and through which oil flows, and the rotating ring having a second passage that communicates with the first passage and supplies oil from the first passage to the gap between the rotating ring and the fixed ring.

[0010] In the present invention configured as described above, oil is supplied to the gap between the rotating ring and the stationary ring in the seal member via the first passage in the rotating shaft and the second passage in the rotating ring of the seal member, thereby effectively preventing refrigerant leakage and lubricating and cooling the sliding surfaces. Specifically, according to the present invention, oil is continuously supplied to the sliding surfaces of the rotating ring and the stationary ring, thereby shortening the time the oil remains on the sliding surfaces and preventing oil sludge formation. Furthermore, a thick oil film is formed on the sliding surfaces, preventing seizure of the sliding surfaces. Furthermore, according to the present invention, the first passage extends inside the rotating shaft, so centrifugal force caused by rotation of the rotating shaft can be applied to the oil in this first passage, allowing the oil supply pressure to be increased according to the motor rotation speed. Therefore, according to the present invention, refrigerant leakage from the seal member and oil sludge and seizure of the sliding surfaces can be prevented even when the motor is operating at high speeds.

[0011] In the present invention, the first passage is preferably formed so as to extend along the axis of the rotary shaft and extend radially from the axis toward the seal member. According to the present invention configured in this manner, the radial extension distance of the first passage is increased, so that a large centrifugal force caused by the rotation of the rotating shaft can be applied to the oil in this first passage, and the oil supply pressure can be effectively increased in accordance with the motor rotation speed.

[0012] In the present invention, the second passage preferably communicates with a supply port for supplying oil to the gap between the rotating ring and the fixed ring, the supply port being formed in the sliding surface of the rotating ring facing the gap. According to the present invention configured in this manner, oil can be supplied directly to the sliding surface from the second passage via the supply port, making it possible to effectively prevent oil sludge and seizure on the sliding surface.

[0013] In the present invention, preferably, the first passage includes a portion extending in the radial direction, and a plurality of such portions are formed along the circumferential direction, and the second passage includes a portion extending in the axial direction, and a plurality of such portions are formed along the circumferential direction. According to the present invention configured in this manner, oil can be supplied uniformly over the entire sliding surfaces of the rotating ring and the fixed ring from the first and second passages formed in multiple locations along the circumferential direction.

[0014] In the present invention, the refrigerant circulation system is preferably configured to circulate a refrigerant in which oil is contained in CO2, and further has an oil tank for storing oil separated from the refrigerant, and the oil stored in the oil tank is supplied to the first passage. According to the present invention configured in this manner, oil can be shared between the lubrication of the sliding bearing using a refrigerant containing oil and the sealing of the refrigerant using oil in the sealing member, making it possible to simplify the system configuration.

[0015] In the present invention, preferably, the oil tank includes a first oil tank that separates oil from the refrigerant flowing out from the motor and stores the oil, and a second oil tank that stores oil supplied from the first oil tank, and the second oil tank is configured to use the pressure of the refrigerant supplied from the compressor to supply the stored oil to the first passage. According to the present invention configured in this manner, oil from the second oil tank is supplied to the first passage by utilizing the pressure from the compressor, so that oil separated from the refrigerant can be supplied to the first passage with a simple configuration.

[0016] In the present invention, preferably, the refrigerant circulation system further includes a pressure reducing valve that reduces the pressure of the oil supplied from the second oil tank to the first passage. According to the present invention configured as described above, oil that has been reduced in pressure by the pressure reducing valve to a pressure suitable for the seal member can be supplied to the first passage. Also, by closing the pressure reducing valve when oil supply to the seal member is not required, it is possible to prevent unnecessary oil from leaking from the second oil tank.

[0017] In a preferred example of the present invention, the seal member further includes a spring that urges the rotary ring toward the fixed ring. In another preferred example, the seal member further includes a spring that urges the fixed ring toward the rotary ring. [Effects of the Invention]

[0018] According to the present invention, in a refrigerant circulation system in which the sliding bearings of a motor are lubricated with a refrigerant and refrigerant leakage is prevented by a sealing member, it is possible to prevent oil sludge from forming on the sealing member and seizure of the sliding surfaces. [Brief explanation of the drawings]

[0019] [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] FIG. 2 is a plan view of a seal member according to an embodiment of the present invention. [Figure 5] 2 is a longitudinal cross-sectional view of a sealing member according to an embodiment of the present invention. FIG. [Figure 6] 6(a) is a cross-sectional view of the seal member taken along line VIa-VIa in FIG. 5, and FIG. 6(b) is a cross-sectional view of the seal member taken along line VIb-VIb in FIG. [Figure 7] FIG. 10 is a cross-sectional view of a seal member according to a modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, a refrigerant circulation system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0021] [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.

[0022] 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.

[0023] 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 (e.g., approximately 10 MPa). The motor 1 is configured to function as an expansion valve and an evaporator in a refrigeration cycle by using the liquid (typically supercritical) 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, high-pressure refrigerant is supplied from the compressor 3 to the heat exchanger 5, a room-temperature, high-pressure supercritical refrigerant is supplied from the heat exchanger 5 to the motor 1, and a room-temperature, low-pressure 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.

[0024] 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.

[0025] [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.

[0026] 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.

[0027] Furthermore, in motor 1, high-pressure refrigerant compressed by compressor 3 is supplied to sliding bearing 14 via refrigerant passage 22. Specifically, refrigerant passage 22 supplies refrigerant to the gap between rotating shaft 13 and sliding bearing 14. Slide bearing 14 is configured to be lubricated using the refrigerant (CO2 refrigerant) supplied in this way from refrigerant passage 22 as a lubricant. In this case, slide bearing 14 is lubricated using a liquid refrigerant (specifically, a refrigerant containing CO2 in a supercritical state).

[0028] 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 that has been compressed into a liquid state (supercritical state) by the compressor 3 is applied to the motor 1. This makes it possible to solve problems such as rolling fatigue and oil agitation resistance.

[0029] After being used for lubrication in the sliding bearing 14, the refrigerant is supplied to the stator 12 and used to cool the stator 12. Thereafter, the refrigerant flows out of the refrigerant passage 24 and is returned to the compressor 3 (FIG. 1).

[0030] In such a motor 1, the refrigerant is supplied from the gap between the rotating shaft 13 and the sliding bearing 14 to the space 15a in the housing 15 in which the rotor 11 and the stator 12 are provided, reducing the pressure, so that the motor 1 functions as an expansion valve in the refrigeration cycle, and also functions as an evaporator in the refrigeration cycle because the refrigerant exchanges heat with the relatively high temperature stator 12 (at which time the refrigerant evaporates in the coil of the stator 12).

[0031] The motor 1 also has a seal member 18 for sealing the side of the rotating shaft 13 that is connected to a transaxle or the like. This seal member 18 is provided to prevent refrigerant leakage from a gap between the housing 15 and the portion of the rotating shaft 13 that extends outward from the housing 15. In particular, in this embodiment, the seal member 18 is configured to receive oil (lubricating oil) from an oil passage 27 that passes through the rotating shaft 13, and to use this oil to prevent leakage of the high-pressure refrigerant compressed by the compressor 3 as described above (details will be described later). The oil used in the seal member 18 flows out of the refrigerant passage 24 together with the refrigerant used in the sliding bearing 14 (the refrigerant and oil are mixed). On the other hand, the end of the rotating shaft 13 opposite the end connected to the transaxle or the like is not provided with such a seal member 18, and is sealed by being covered by the housing 15.

[0032] [Configuration of 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.

[0033] 3, in addition to the motor 1, compressor 3, and heat exchanger 5 described above (FIG. 1), the refrigerant circulation system 100 also includes first and second oil tanks 6 and 7 for storing oil used as a refrigerant, and an air conditioner evaporator 8 used in an air conditioner in a vehicle 200. In addition to refrigerant passages 22 and 24 and an oil passage 27 connected to the motor 1 (FIG. 2), the refrigerant circulation system 100 also includes refrigerant passages 21, 25, and 28 through which the refrigerant flows, and an oil passage 26 through which oil flows.

[0034] Refrigerant passage 21 is a passage for supplying refrigerant from compressor 3 via heat exchanger 5 to motor 1, and is connected to refrigerant passages 22 and 28. As described above, refrigerant passage 22 is a passage for supplying refrigerant to sliding bearing 14 of motor 1 (FIG. 2). Refrigerant passage 28 is a passage used for the air conditioning in vehicle 200, and is provided with air conditioning evaporator 8 and an expansion valve 34 that decompresses the refrigerant.

[0035] Refrigerant passage 24 carries the refrigerant (including the oil used in sealing member 18) flowing from motor 1, and is connected to first oil tank 6, which stores the oil. First oil tank 6 separates the oil from the refrigerant supplied from refrigerant passage 24 (gas-liquid separation) and stores the separated oil. In addition, first oil tank 6 is connected to refrigerant passage 25, and the refrigerant (which also contains a small amount of oil) from which the oil has been separated is supplied to compressor 3 via refrigerant passage 25. Note that refrigerant flowing from air-conditioning evaporator 8 also flows into refrigerant passage 25.

[0036] Furthermore, an oil passage 26 is connected to the first oil tank 6. One end of this oil passage 26 is connected to the first oil tank 6, and the other end is connected to the second oil tank 7. In addition, an oil pump 30 that pumps oil and a check valve 31 are provided on the oil passage 26.

[0037] The second oil tank 7 is provided on the refrigerant passage 21 and stores oil supplied from the first oil tank 6 by the oil pump 30. The second oil tank 7 is also connected to the above-mentioned oil passage 27, and supplies oil to the seal member 18 of the motor 1 via this oil passage 27 (FIG. 2). In this case, the second oil tank 7 supplies the stored oil to the oil passage 27 by utilizing the pressure of the refrigerant supplied from the compressor 3 via the refrigerant passage 21. A pressure reducing valve 32 is also provided on the oil passage 27 to reduce the pressure of the oil supplied from the second oil tank 7. When this pressure reducing valve 32 is closed, the supply of oil to the seal member 18 is stopped.

[0038] [Sealing material configuration] Next, the seal member 18 according to this embodiment will be described in detail with reference to Figs. 4 to 6. Fig. 4 is a plan view of the seal member 18 according to this embodiment (including the rotating shaft 13; the same applies below). Fig. 5 is a longitudinal cross-sectional view of the seal member 18 according to this embodiment as viewed along the axial direction. Fig. 6(a) is a transverse cross-sectional view of the seal member 18 as viewed along VIa-VIa in Fig. 5, and Fig. 6(b) is a transverse cross-sectional view of the seal member 18 as viewed along VIb-VIb in Fig. 5. Note that in Figs. 4 and 5, the inside of the housing 15 of the motor 1 (space 15a in which the refrigerant is sealed) is shown on the right, and the outside of the housing 15 (atmospheric side) is shown on the left.

[0039] As shown in Figures 4 and 5, the seal member 18 is attached to the rotary shaft 13 and is formed into a generally cylindrical shape as a whole so as to surround the outer periphery of the rotary shaft 13. The seal member 18 is also fixed to the housing 15 (Figure 2), not shown. As shown in Figure 5 in particular, the seal member 18 includes a rotary ring 51 attached to the outer periphery of the rotary shaft 13 so as to be movable in the axial direction and rotate together with the rotary shaft 13, and a fixed ring 58 fixed to the housing 15 (more specifically, fixed to the housing 15 via a retaining portion 59) so as not to rotate together with the rotary shaft 13 and provided adjacent to the rotary ring 51 in the axial direction so as to slide on the rotary ring 51. The seal member 18 is configured to seal the gap (Figure 2) between the rotary shaft 13 and the housing 15 by means of the rotary ring 51 and the fixed ring 58. That is, the sliding surfaces 51a, 58a of the rotating ring 51 and the fixed ring 58 come into contact with each other (strictly speaking, oil, which will be described later, is present between the sliding surfaces 51a, 58a, i.e., there is a gap for the oil), thereby sealing the gap between the rotating shaft 13 and the housing 15. In the following, when there is no need to distinguish between the sliding surfaces 51a, 58a of the rotating ring 51 and the fixed ring 58, they will be simply referred to as "sliding surfaces" without being given reference numerals.

[0040] 5, the seal member 18 includes, in addition to the rotating ring 51 and fixed ring 58 described above, a spring 52 for pressing (biasing) the rotating ring 51 against the fixed ring 58, a pressing portion 53 to which one end of the spring 52 is connected and which applies the pressing force from the spring 52 to the rotating ring 51, a cup portion 55 that houses the other end of the spring 52 and has an open portion facing the rotating ring 51, O-rings 56 and 57 that are provided on the inner circumferential surface of the rotating ring 51 and seal the gap between the rotating ring 51 and the rotating shaft 13, and a holding portion 59 that holds the fixed ring 58 and is fixed to the housing 15. The pressing force from the spring 52 and the pressure of the refrigerant in the space 15a are applied to the rotating ring 51 via the pressing portion 53 (arrow A11), and as a result, the rotating ring 51 moves axially and is pressed against the fixed ring 58 (arrow A12).

[0041] Furthermore, an oil passage 27 through which oil flows, i.e., an oil passage 27 to which oil is supplied from the second oil tank 7 (FIG. 3) described above, is formed in the rotary shaft 13 and the rotary ring 51 of the seal member 18. Specifically, the oil passage 27 has an oil passage 27a extending into the rotary shaft 13, and an oil passage 27b communicating with this oil passage 27a and extending into the rotary ring 51. The oil passages 27a and 27b correspond to the "first passage" and "second passage" of the present invention, respectively.

[0042] Specifically, oil passage 27a has a portion 27a1 extending along the axis (center) of rotating shaft 13 and a portion 27a2 extending radially from the axis toward seal member 18. Oil passage 27b has a portion 27b1 extending radially away from rotating shaft 13 and a portion 27b2 extending axially toward stationary ring 58. In this case, oil passage 27b is formed to directly supply oil from oil passage 27a to the gap between rotating ring 51 and stationary ring 58 (i.e., the sliding surfaces of rotating ring 51 and stationary ring 58). Specifically, oil passage 27b communicates with a supply port 27b3 for supplying oil, and this supply port 27b3 is formed in the sliding surface 51a of rotating ring 51 with stationary ring 58. Oil is supplied to the sliding surfaces of rotating ring 51 and stationary ring 58 from oil passage 27b and supply port 27b3. After this, the oil is discharged from the sliding surface into the space 15a of the housing 15 by centrifugal force, and flows out of the refrigerant passage 24 together with the refrigerant used for lubrication in the sliding bearing 14 (the refrigerant and oil are mixed) (Figure 2).

[0043] In the seal member 18 according to this embodiment, oil is supplied directly to the sliding surfaces from the oil passage 27b and the supply port 27b3, thereby effectively sealing the refrigerant and lubricating and cooling the sliding surfaces. In particular, according to this embodiment, oil is continuously supplied to the sliding surfaces, thereby shortening the time the oil remains on the sliding surfaces and preventing the formation of oil sludge. Furthermore, a thick oil film is formed on the sliding surfaces, thereby reducing sliding resistance and preventing seizure of the sliding surfaces.

[0044] More specifically, in this embodiment, oil passage 27a that supplies oil is formed to include radially extending portion 27a2, so that centrifugal force caused by the rotation of rotating shaft 13 can be applied to the oil in oil passage 27a (arrow A13), thereby increasing the oil supply pressure according to the motor rotation speed. Therefore, even when motor 1 is operating at high speed, oil sludge and seizure of the sliding surfaces can be effectively prevented.

[0045] As shown in Fig. 6(a), oil passage 27a has a plurality of radially extending portions 27a2 formed along the circumferential direction, in other words, a plurality of portions 27a2 formed to extend radially from the axis. As shown in Fig. 6(b), oil passage 27b has a plurality of axially extending portions 27b2 formed along the circumferential direction. By forming a plurality of oil passages 27a and 27b in the circumferential direction in this manner, oil can be supplied uniformly over the entire sliding surfaces of rotating ring 51 and fixed ring 58.

[0046] 5, the diameter of the rotating shaft 13 is narrowed at the portion where the fixed ring 58 and part of the rotating ring 51 are provided, thereby shortening the rotation radius of the sliding surfaces of the rotating ring 51 and the fixed ring 58. This reduces the speed along the circumferential direction at the sliding surfaces, effectively preventing the above-mentioned oil sludge and seizure of the sliding surfaces.

[0047] [Action and effect] Next, the operation and effect of the refrigerant circulation system 100 according to this embodiment will be described. In this embodiment, the refrigerant circulation system 100, which circulates a refrigerant containing CO2, includes a compressor 3 that compresses the refrigerant, a rotor 11 and a stator 12, a rotating shaft 13 connected to the rotor 11, a housing 15 that accommodates the rotor 11, the stator 12, and the rotating shaft 13, a motor 1 that includes a sliding bearing 14 that supports the rotating shaft 13 and is lubricated using the liquid refrigerant compressed by the compressor 3, and a seal member 18 that is attached to the outer periphery of the rotating shaft 13 to prevent refrigerant leakage from a gap between the housing 15 and the portion of the rotating shaft 13 that extends outward from the housing 15. The housing 15 includes a rotating ring 51 that rotates together with the rotating shaft 13, and a fixed ring 58 that is fixed to the housing 15 and is provided adjacent to the rotating ring 51 in the axial direction so as to slide against the rotating ring 51, and a seal member 18 that is configured to seal a gap between the rotating ring 51 and the fixed ring 58. The rotating shaft 13 is formed with an oil passage 27a that extends into the rotating shaft 13 and through which oil flows, and the rotating ring 51 is formed with an oil passage 27b that communicates with the oil passage 27a and supplies oil from the oil passage 27a to the gap between the rotating ring 51 and the fixed ring 58.

[0048] According to this embodiment, oil is supplied to the gap between the rotating ring 51 and the stationary ring 58 of the seal member 18 via the oil passage 27a in the rotating shaft 13 and the oil passage 27b in the rotating ring 51 of the seal member 18, thereby effectively preventing refrigerant leakage and lubricating and cooling the sliding surfaces. Specifically, according to this embodiment, oil is continuously supplied to the sliding surfaces of the rotating ring 51 and the stationary ring 58, thereby shortening the time the oil remains on the sliding surfaces and preventing oil sludge formation. Furthermore, a thick oil film is formed on the sliding surfaces, preventing seizure of the sliding surfaces. Furthermore, according to this embodiment, because the oil passage 27a extends into the rotating shaft 13, centrifugal force due to the rotation of the rotating shaft 13 can be applied to the oil in this oil passage 27a, thereby increasing the oil supply pressure according to the motor rotation speed. Therefore, according to this embodiment, it is possible to prevent refrigerant leakage from the seal member 18 and prevent oil sludge and seizure of the sliding surfaces when the motor 1 is operating at high speeds.

[0049] Furthermore, according to this embodiment, oil passage 27a is formed to extend along the axis of rotating shaft 13 and also extend radially from the axis toward seal member 18. This increases the radial extension distance of oil passage 27a, allowing a large centrifugal force caused by the rotation of rotating shaft 13 to act on the oil in oil passage 27a, effectively increasing the oil supply pressure in accordance with the motor rotation speed.

[0050] Furthermore, according to this embodiment, oil passage 27b communicates with supply port 27b3 for supplying oil to the gap between rotating ring 51 and fixed ring 58, and supply port 27b3 is formed in sliding surface 51a of rotating ring 51. This allows oil to be directly supplied to the sliding surface from oil passage 27b via supply port 27b3, effectively preventing oil sludge and seizure of the sliding surface.

[0051] Furthermore, according to this embodiment, oil passage 27a includes a portion 27a2 extending in the radial direction, and a plurality of such portions 27a2 are formed along the circumferential direction, while oil passage 27b includes a portion 27b2 extending in the axial direction, and a plurality of such portions 27b2 are formed along the circumferential direction. This allows oil to be supplied uniformly over the entire sliding surfaces of rotating ring 51 and fixed ring 58.

[0052] Furthermore, according to this embodiment, refrigerant circulation system 100 is configured to circulate a refrigerant in which CO2 contains oil, and further includes oil tanks (first and second oil tanks 6, 7) that store oil separated from the refrigerant, and oil passage 27a is supplied with the oil stored in this manner. As a result, in refrigerant circulation system 100 that circulates refrigerant, oil can be shared between lubrication using an oil-containing refrigerant in sliding bearing 14 and refrigerant sealing using oil in seal member 18, making it possible to simplify the system configuration.

[0053] Furthermore, according to this embodiment, refrigerant circulation system 100 has a first oil tank 6 that separates oil from the refrigerant flowing out from motor 1 and stores the oil, and a second oil tank 7 that stores oil supplied from first oil tank 6, and second oil tank 7 is configured to supply the stored oil to oil passage 27a by utilizing the pressure of the refrigerant supplied from compressor 3. This makes it possible to supply oil separated from the refrigerant to oil passage 27a with a simple configuration and at low cost (because a pump or the like is not required).

[0054] Furthermore, according to this embodiment, the refrigerant circulation system 100 further includes a pressure reducing valve 32 that reduces the pressure of oil supplied from the second oil tank 7 to the oil passage 27a. This allows the oil that has been reduced in pressure by the pressure reducing valve 32 to a pressure suitable for the seal member 18 to be supplied to the oil passage 27a. Furthermore, by closing the pressure reducing valve 32 when it is not necessary to supply oil to the seal member 18, it is possible to prevent unnecessary oil from flowing out of the second oil tank 7.

[0055] [Variations] Next, a sealing member according to a modification of the above-described embodiment will be described with reference to Fig. 7. Like Fig. 5, Fig. 7 is a longitudinal cross-sectional view of the sealing member according to the modification (including the rotating shaft 13) as viewed along the axial direction. Note that, in the following, descriptions of configurations similar to those of the above-described embodiment will be omitted as appropriate. In other words, configurations not specifically described here are assumed to be similar to those of the above-described embodiment.

[0056] The seal member 18a according to the modified example is also attached to the rotating shaft 13, has a generally cylindrical shape as a whole so as to surround the outer periphery of the rotating shaft 13, and is fixed to the housing 15 (FIG. 2), not shown. Specifically, as shown in FIG. 7, the seal member 18a includes a rotating ring 61 attached to the outer periphery of the rotating shaft 13 and rotating together with the rotating shaft 13, and a fixed ring 66 fixed to the housing 15 (more specifically, fixed to the housing 15 via a retaining portion 67) so as not to rotate together with the rotating shaft 13, and provided adjacent to the rotating ring 61 in the axial direction so as to slide on the rotating ring 61. The fixed ring 66 is also configured to be movable in the axial direction. The seal member 18a is configured to seal the gap (FIG. 2) between the rotating shaft 13 and the housing 15 by the rotating ring 61 and the fixed ring 66. That is, the sliding surfaces 61a, 66a of the rotating ring 61 and the fixed ring 66 come into contact with each other (strictly speaking, oil, which will be described later, is present between the sliding surfaces 61a, 66a, i.e., there is a gap for the oil), thereby sealing the gap between the rotating shaft 13 and the housing 15. In the following, when there is no need to distinguish between the sliding surfaces 61a, 66a of the rotating ring 61 and the fixed ring 66, they will be simply referred to as "sliding surfaces" without being given reference numerals.

[0057] Specifically, in addition to the above-described rotary ring 61 and fixed ring 66, the seal member 18a has a retaining portion 63 fixed to the rotary shaft 13 for retaining the rotary ring 61, O-rings 64 and 65 for sealing a gap between the rotary ring 61 and the retaining portion 63, a retaining portion 67 fixed to the housing 15 for retaining the stationary ring 66 and the like, a spring 68 having one end connected to the stationary ring 66 and the other end connected to the retaining portion 67 (more specifically, housed in a recess 67a formed in the retaining portion 67) for pressing (biasing) the stationary ring 66 against the rotary ring 61, and an O-ring 69 for sealing a gap between the stationary ring 66 and the retaining portion 67. A pressing force is applied to the stationary ring 66 from the spring 68 (arrow A21), and as a result, the stationary ring 66 moves axially and is pressed against the rotary ring 61 (arrow A22).

[0058] Furthermore, an oil passage 27 through which oil flows, i.e., an oil passage 27 to which oil is supplied from the second oil tank 7 (FIG. 3) described above, is formed in the rotating shaft 13, the rotating ring 61 of the seal member 18a, and the retaining portion 63. Specifically, the oil passage 27 has an oil passage 27c extending into the rotating shaft 13, an oil passage 27d communicating with this oil passage 27c and extending into the retaining portion 63, and an oil passage 27e communicating with this oil passage 27d and extending into the rotating ring 61. The oil passages 27c and 27e correspond to the "first passage" and "second passage" in the present invention, respectively.

[0059] Furthermore, oil passage 27e is formed to supply oil from oil passage 27d directly to the gap between the rotating ring 61 and the fixed ring 66 (i.e., the sliding surfaces of the rotating ring 61 and the fixed ring 66). More specifically, oil passage 27e communicates with a supply port 27e1 for supplying oil, and this supply port 27e1 is formed on the sliding surface 61a of the rotating ring 61 with the fixed ring 66. Oil is supplied from oil passage 27e and supply port 27e1 to the sliding surfaces of the rotating ring 61 and the fixed ring 66. The oil is then discharged from the sliding surfaces into space 15a of housing 15 by centrifugal force, and flows out of refrigerant passage 24 together with the refrigerant used to lubricate the sliding bearing 14 (the refrigerant and oil are mixed together) (FIG. 2).

[0060] Even with this modification, oil sludge and seizure on the sliding surfaces can be prevented by directly supplying oil to the sliding surfaces from oil passage 27e and supply port 27e1. Furthermore, because oil passage 27c extends into rotating shaft 13, centrifugal force due to the rotation of rotating shaft 13 can be applied to the oil in oil passage 27c (arrow A23), increasing the oil supply pressure according to the motor rotation speed. Therefore, even with this modification, refrigerant leakage from seal member 18a can be prevented when motor 1 is operating at high speed, while also preventing oil sludge and seizure on the sliding surfaces.

[0061] Furthermore, according to the modified example, unlike the embodiment in which the rotating rotating ring 51 is biased toward the fixed ring 58 by the spring 52 (FIG. 5), the non-rotating fixed ring 66 is biased toward the rotating ring 61 by the spring 68, which makes it easier to accommodate high rotation speeds of the motor 1 compared to the embodiment. [Explanation of symbols]

[0062] 1 motor 3 Compressor 5 Heat exchanger 6. First Oil Tank 7. Second oil tank 11 rotor 12 Stator 13 Rotation axis 14 Plain bearings 15 Housing 18, 18a sealing member 21, 22, 24, 25 Refrigerant passages 26, 27 Oil passages 32 Pressure reducing valve 51, 61 Rotating ring 58, 66 fixed ring 52, 68 Spring 100 Refrigerant Circulation System 200 vehicles

Claims

1. CO 2 A refrigerant circulation system that circulates a refrigerant including: a compressor that compresses the refrigerant; a motor including a rotor, a stator, a rotating shaft connected to the rotor, a housing that accommodates the rotor, the stator, and the rotating shaft, and a sliding bearing that supports the rotating shaft and is lubricated using the liquid refrigerant compressed by the compressor; a seal member for preventing leakage of the refrigerant from a gap between the housing and a portion of the rotating shaft extending outward from the housing, the seal member comprising: a rotating ring attached to an outer periphery of the rotating shaft and rotating together with the rotating shaft; and a fixed ring fixed to the housing and provided adjacent to the rotating ring in the axial direction so as to slide on the rotating ring, the seal member being configured to seal the gap with the rotating ring and the fixed ring; and a first passage extending inside the rotary shaft and through which oil flows is formed in the rotary shaft; The rotary ring is formed with a second passage that is in communication with the first passage and that supplies the oil from the first passage to a gap between the rotary ring and the fixed ring. A refrigerant circulation system.

2. The refrigerant circulation system according to claim 1 , wherein the first passage extends along an axis of the rotary shaft and extends radially from the axis toward the seal member.

3. 3. The refrigerant circulation system according to claim 1, wherein the second passage is connected to a supply port for supplying the oil to the gap between the rotating ring and the fixed ring, the supply port being formed on a sliding surface of the rotating ring facing the gap.

4. the first passage includes a portion extending in a radial direction, and a plurality of such portions are formed along a circumferential direction, The second passage includes a portion extending in the axial direction, and a plurality of such portions are formed along the circumferential direction.

3. The refrigerant circulation system according to claim 1 or 2.

5. The refrigerant circulation system 2 the oil tank is configured to circulate the refrigerant containing the oil through the refrigerant tank, and further includes an oil tank that stores the oil separated from the refrigerant, The oil stored in the oil tank is supplied to the first passage. The refrigerant circulation system according to claim 1 or 2.

6. the oil tank includes a first oil tank that separates the oil from the refrigerant flowing out of the motor and stores the oil, and a second oil tank that stores the oil supplied from the first oil tank, The second oil tank is configured to supply the oil stored therein to the first passage by utilizing the pressure of the refrigerant supplied from the compressor. The refrigerant circulation system according to claim 5 .

7. The refrigerant circulation system according to claim 6 , further comprising a pressure reducing valve that reduces the pressure of the oil supplied from the second oil tank to the first passage.

8. The refrigerant circulation system according to claim 1 or 2, wherein the seal member further includes a spring that biases the rotary ring toward the fixed ring.

9. The refrigerant circulation system according to claim 1 or 2, wherein the seal member further includes a spring that biases the stationary ring toward the rotary ring.

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