Coolant circulation system

Abstract

To provide a coolant circulation system to lubricant a slide bearing of a motor with a coolant containing oil, in which the contact between a rotary shaft and the slide bearing is avoided.SOLUTION: A coolant circulation system 100 to circulate a coolant in which CO2 contains oil includes a motor 1 including a pair of slide bearings 14 that lubricates using a coolant compressed with a compressor 3 and supports a rotary shaft 13, a plurality of coolant passages 22 provided to supply the coolant to a plurality of positions in an axial direction in each of the pair of slide bearings, a plurality of first flow rate regulation valves 30 that regulates the oil content ratio in the coolant supplied from these coolant passages, and a control device 80 that, in the case where there is a possibility that the rotary shaft comes into contact with the slide bearing, controls the first flow rate regulation valve so that the oil content ratio from the coolant passage provided at the place with the contact possibility becomes larger than the oil content ratio from the other coolant passages.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] Conventionally, refrigerant circulation systems have been used in refrigeration cycles used in air conditioners and the like, in which a refrigerant is circulated through a compressor, a heat exchanger, and the like. In this type of refrigerant circulation system, a refrigerant containing oil (refrigerating machine oil) is generally used to lubricate and seal the compressor, and this oil also circulates within the system. For example, Patent Document 1 discloses a technology in which, at the start of the system, the oil-containing refrigerant discharged from the compressor is separated and the oil is extracted, and only the oil is supplied to the suction side of the compressor, thereby sufficiently lubricating the compressor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-170457 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 liquefies when compressed by a compressor.At the same time, the present inventors considered using a refrigerant that contains oil, as described above, to ensure the lubrication of the motor's sliding bearing.

[0006] Here, when the vehicle collides (which generates a large impact load) or when the vehicle experiences large acceleration in the longitudinal, lateral, yaw, roll, or pitch directions, the rotating shaft of the motor may tilt, causing the rotating shaft to come into contact with the sliding bearing. In such cases, it would be ideal to use oil to improve the load capacity of the sliding bearing, thereby preventing contact between the rotating shaft and the sliding bearing.

[0007] The present invention has been made to solve the problems of the conventional technology described above, and has an object to prevent contact between the rotating shaft of a motor and the sliding bearing in a refrigerant circulation system that circulates an oil-containing refrigerant and uses this refrigerant to lubricate the sliding bearing of a motor. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a refrigerant circulation system that circulates a refrigerant in which oil is contained in CO2, the system comprising: a motor including a compressor that compresses the refrigerant; a rotor and a stator; a rotating shaft connected to the rotor; and a pair of plain bearings that support the rotating shaft and are lubricated with a liquid refrigerant compressed by the compressor; a refrigerant passage that supplies the refrigerant to the plain bearing of the motor; an oil content adjustment valve configured to adjust the oil content of the refrigerant that is supplied from the refrigerant passage to the plain bearing; a contact determination device configured to determine the possibility of the rotating shaft of the motor coming into contact with the plain bearing; and a control device configured to control the oil content adjustment valve, a plurality of passages are provided in each of the pair of plain bearings to supply refrigerant to a plurality of axial positions, a plurality of oil content adjustment valves are provided to adjust the oil content of the refrigerant supplied from the plurality of refrigerant passages, and the control device is configured to, when the contact determination device determines that there is a possibility that the rotating shaft may come into contact with the plain bearing, control each of the plurality of oil content adjustment valves so that the oil content from one or more refrigerant passages provided at locations among the plurality of refrigerant passages that correspond to positions where the rotating shaft may come into contact with the plain bearing is greater than the oil content from other refrigerant passages other than the one or more refrigerant passages.

[0009] In the present invention configured in this manner, if the rotating shaft of the motor tilts due to, for example, the state of the vehicle, and there is a possibility that the rotating shaft will come into contact with the sliding bearing, the control device increases the oil content in one or more refrigerant passages located at locations corresponding to the position of potential contact, thereby locally increasing the viscosity of the refrigerant in the sliding bearing near these refrigerant passages.In other words, it is possible to locally increase the load capacity near the position where the rotating shaft may come into contact with the sliding bearing.This makes it possible to accurately avoid contact between the rotating shaft and the sliding bearing.

[0010] In the present invention, preferably, a plurality of refrigerant passages are provided along the axial direction, and a plurality of refrigerant passages are provided along the circumferential direction of the sliding bearing. According to the present invention configured in this manner, it is possible to selectively increase the local load capacity at various positions in the axial and circumferential directions within the sliding bearing.

[0011] In the present invention, the refrigerant circulation system is preferably mounted on a vehicle, and the one or more refrigerant passages controlled by the control device to increase the oil content include, when yawing occurs in the vehicle, a refrigerant passage located at the front of the multiple refrigerant passages provided in one of the pair of plain bearings, and a refrigerant passage located at the rear of the multiple refrigerant passages provided in the other of the pair of plain bearings. According to the present invention configured in this manner, it is possible to locally increase the viscosity of the refrigerant near the position of the sliding bearing with which the rotating shaft may come into contact during large yawing of the vehicle, i.e., to locally increase the load capacity, thereby reliably preventing contact between the rotating shaft and the sliding bearing due to large yawing.

[0012] In the present invention, the refrigerant circulation system is preferably mounted on a vehicle, and the one or more refrigerant passages controlled by the control device to increase the oil content include, when rolling occurs in the vehicle, an upper refrigerant passage among the multiple refrigerant passages provided in one of the pair of plain bearings, and a lower refrigerant passage among the multiple refrigerant passages provided in the other of the pair of plain bearings. With this configuration, the present invention can locally increase the viscosity of the refrigerant near the position of the sliding bearing with which the rotating shaft may come into contact when the vehicle is undergoing large rolling movements, i.e., locally increase the load capacity, thereby reliably preventing contact between the rotating shaft and sliding bearing due to large rolling movements.

[0013] In the present invention, the refrigerant circulation system is preferably mounted on a vehicle, and the one or more refrigerant passages controlled by the control device to increase the oil content are preferably configured to include, in the event of pitching occurring in the vehicle, an upper refrigerant passage among multiple refrigerant passages provided on one axial side of each of the pair of sliding bearings, and a lower refrigerant passage among multiple refrigerant passages provided on the other axial side. With this configuration, the present invention can locally increase the viscosity of the refrigerant near the position of the sliding bearing with which the rotating shaft may come into contact during large pitching of the vehicle, thereby locally increasing the load capacity. This effectively prevents contact between the rotating shaft and the sliding bearing due to large pitching.

[0014] In the present invention, the control device is preferably configured to control each of the plurality of oil content adjustment valves so that the oil content from one or more refrigerant passages is approximately 100% and the oil content from other refrigerant passages is approximately 0%. According to the present invention configured in this manner, it is possible to effectively increase the load capacity in the vicinity of the position where the rotating shaft may come into contact with the sliding bearing.

[0015] In the present invention, the contact determination device preferably includes a shaft center position sensor that detects the shaft center position of the rotating shaft, and is configured to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on the output of the shaft center position sensor. According to the present invention configured in this manner, it is possible to accurately determine the possibility of the rotating shaft coming into contact with the sliding bearing, based on the actual axial position of the rotating shaft within the sliding bearing (the radial position of the axial center of the rotating shaft).

[0016] In the present invention, the refrigerant circulation system is preferably mounted on a vehicle, and the contact determination device is equipped with one or more sensors that detect acceleration occurring in the vehicle in at least one of the longitudinal, lateral, yaw, pitch, and roll directions, and is configured to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on the output of the one or more sensors. According to the present invention configured in this manner, it is possible to accurately determine the possibility of the rotating shaft coming into contact with the sliding bearing, based on various accelerations that occur in the vehicle.

[0017] In the present invention, the refrigerant circulation system is preferably mounted on a vehicle, and the contact determination device is equipped with an external information acquisition device that acquires external information about the vehicle, and is configured to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on the external information acquired by the external information acquisition device. According to the present invention configured in this manner, it is possible to accurately determine the possibility of the rotating shaft coming into contact with the sliding bearing based on various pieces of information outside the vehicle.

[0018] In the present invention, preferably, the refrigerant circulation system further includes an oil passage that supplies oil to the refrigerant passage, and an oil tank connected to the oil passage that stores the oil, and the oil tank is configured to separate the oil contained in the refrigerant and store the oil. According to the present invention configured as described above, the oil can be appropriately recovered from the refrigerant and stored in the oil tank.

[0019] In a preferred example of the present invention, if the refrigerant passage is referred to as a first refrigerant passage, the refrigerant circulation system further has a second refrigerant passage that communicates with the first refrigerant passage and allows refrigerant from the compressor to flow into the first refrigerant passage, and the oil content adjustment valve communicates with the first refrigerant passage, the second refrigerant passage, and the oil passage; thereby, by controlling the oil content adjustment valve, it is possible to change the mixing ratio of refrigerant from the second refrigerant passage and oil from the oil passage and adjust the oil content in the refrigerant supplied from the first refrigerant passage to the sliding bearing. According to the present invention configured in this manner, the oil content in the refrigerant supplied to the sliding bearing can be accurately adjusted by the oil content adjustment valve. [Effects of the Invention]

[0020] According to the present invention, in a refrigerant circulation system in which an oil-containing refrigerant is circulated and the sliding bearing of a motor is lubricated by this refrigerant, contact between the rotating shaft of the motor and the sliding bearing can be avoided. [Brief explanation of the drawings]

[0021] [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] 3 is a schematic configuration diagram for specifically explaining a first flow rate adjustment valve and a refrigerant passage according to the embodiment of the present invention. FIG. [Figure 5] FIG. 2 is a schematic diagram for specifically explaining a plurality of refrigerant passages provided in the axial direction in the embodiment of the present invention. [Figure 6] 1 is a block diagram showing an electrical configuration of a refrigerant circulation system according to an embodiment of the present invention. [Figure 7] 3A and 3B are explanatory diagrams of basic control at the time of starting and stopping according to an embodiment of the present invention. [Figure 8] FIG. 1 is an illustration of basic control during normal operation according to an embodiment of the present invention. [Figure 9] 5A and 5B are explanatory diagrams of contact avoidance control during yawing according to an embodiment of the present invention. [Figure 10] FIG. 10 is an explanatory diagram of contact avoidance control during rolling according to an embodiment of the present invention. [Figure 11] FIG. 10 is an explanatory diagram of contact avoidance control during pitching according to an embodiment of the present invention. [Figure 12]4 is a flowchart illustrating a basic control according to an embodiment of the present invention. [Figure 13] 4 is a flowchart showing contact avoidance control according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, a refrigerant circulation system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0023] [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.

[0024] 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.

[0025] 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 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.

[0026] 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.

[0027] [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.

[0028] 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 (14a, 14b) that support the rotating shaft 13, and a housing 15 that houses the rotor 11, stator 12, rotating shaft 13, plain bearings 14, etc.

[0029] Furthermore, in the motor 1, the refrigerant compressed by the compressor 3 is supplied to the sliding bearing 14 and the stator 12 via refrigerant passages 22 and 23. Specifically, the refrigerant is supplied through refrigerant passage 22 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 in this way from refrigerant passage 22 as a lubricant. In this case, the sliding bearing 14 is lubricated using a liquid refrigerant (specifically, a refrigerant containing CO2 in a supercritical state).

[0030] 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.

[0031] The refrigerant supplied from refrigerant passage 23 is used to cool stator 12, more specifically, to cool the coil (not shown) of stator 12. The refrigerant used to cool stator 12 in this way, and the refrigerant used to lubricate plain bearing 14 as described above, flows out of refrigerant passage 24 and is returned to compressor 3 ( FIG. 1 ). Note that the refrigerant after being used to lubricate plain bearing 14 is also supplied to stator 12 and used to cool stator 12.

[0032] 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).

[0033] Furthermore, motor 1 further includes a seal member 18 for sealing the side of rotating shaft 13 that is connected to a transaxle or the like (the side where plain bearing 14a is provided). This seal member 18 is provided to prevent refrigerant from leaking to the outside from a gap between rotating shaft 13 and housing 15. On the other hand, the end of rotating shaft 13 opposite the side connected to the transaxle or the like (the side where plain bearing 14b is provided) does not have such a seal member 18, and is sealed by being covered by housing 15.

[0034] [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.

[0035] As shown in Fig. 3, in addition to the motor 1, compressor 3, and heat exchanger 5 described above (Fig. 1), the refrigerant circulation system 100 also includes an oil tank 6 that stores oil used as a refrigerant, a pressure reduction tank 7 that stores negative pressure for reducing the pressure inside the space 15a of the motor 1, and an air conditioner evaporator 8 that is used in the air conditioner of the vehicle 200. In addition to refrigerant passages 22, 23, and 24 connected to the motor 1 (Fig. 2), the refrigerant circulation system 100 also includes refrigerant passages 21, 28, and 29 through which the refrigerant flows, oil passages 25 and 26 through which the oil flows, and a pressure reduction passage 27 for reducing the pressure using the pressure reduction tank 7. The refrigerant passage 22 and the refrigerant passage 21 correspond to the "first refrigerant passage" and the "second refrigerant passage," respectively, in the present invention.

[0036] Specifically, refrigerant passage 21 is a passage for supplying refrigerant from compressor 3 to motor 1 via heat exchanger 5, and is connected to both refrigerant passages 22 and 23. As described above, refrigerant passage 22 is a passage for supplying refrigerant to the sliding bearing 14 of motor 1, and refrigerant passage 23 is a passage for supplying refrigerant to the stator 12 of motor 1 (FIG. 2). Refrigerant passage 22 is connected to refrigerant passage 21 and oil passage 25 via first flow control valve 30, a three-way valve with an adjustable opening. This allows refrigerant obtained by mixing refrigerant from refrigerant passage 21 with oil from oil passage 25 to flow through refrigerant passage 22 and be supplied to the sliding bearing 14 of motor 1. In this case, by controlling the opening of first flow control valve 30, the mixing ratio of refrigerant from refrigerant passage 21 and oil from oil passage 25 can be changed, making it possible to adjust the oil content of the refrigerant supplied from refrigerant passage 22 to the sliding bearing 14. In addition, refrigerant passage 22 is provided with a pressure sensor 40 that detects the pressure of the refrigerant. On the other hand, the refrigerant passage 23 is connected to the refrigerant passage 21 upstream of the first flow rate control valve 30, and is provided with a second flow rate control valve 31 that adjusts the flow rate of the refrigerant. The first flow rate control valve 30 corresponds to the "oil content adjustment valve" in this invention.

[0037] Refrigerant passage 24 is a passage for supplying (recirculating) the refrigerant flowing out from motor 1 to compressor 3, and is provided with a pressure sensor 41 that detects pressure, an oil tank 6 that stores oil, and a check valve 36. The pressure sensor 41 detects the pressure of the refrigerant upstream of oil tank 6 (corresponding to the pressure in space 15a of motor 1 and the pressure in oil tank 6). Oil tank 6 is configured to separate the oil from the refrigerant flowing through refrigerant passage 24 (gas-liquid separation) and store the separated oil while allowing the remaining refrigerant (which may also contain a small amount of oil) to flow downstream to compressor 3. In addition, oil tank 6 is provided with an oil level sensor 43 that detects the level of the stored oil.

[0038] Furthermore, the oil tank 6 is connected to the oil passage 25. One end of this oil passage 25 is connected to the oil tank 6, and the other end is connected to the refrigerant passage 21 and the refrigerant passage 22 via the first flow control valve 30. The oil passage 25 supplies oil stored in the oil tank 6 to the refrigerant passage 22 via the first flow control valve 30, so that the refrigerant mixed with the oil from the refrigerant passage 21 can be supplied to the sliding bearing 14 of the motor 1. Specifically, an oil pump 32 that pumps oil and an oil pressure sensor 42 that detects the oil pressure (oil pressure) are provided on the oil passage 25. Furthermore, an oil passage 26 for returning oil is further connected to the oil tank 6. Typically, the oil passage 26 functions to return oil that did not flow through the oil passage 25 to the oil tank 6 via a check valve (relief valve) 37 when the oil passage 26 side of the first flow control valve 30 is closed.

[0039] One end of the pressure reduction passage 27 is connected to the oil tank 6, specifically to the refrigerant passage 24 via the oil tank 6, and the other end is connected to the refrigerant passage 24 downstream of the oil tank 6. The pressure reduction passage 27 is provided with a pressure reduction tank 7, a pressure reduction valve 34, and a check valve 38. Negative pressure created by the operation of the compressor 3 is supplied to the pressure reduction tank 7 via the pressure reduction passage 27 and refrigerant passage 24 on the downstream side (compressor 3 side) of the pressure reduction tank 7, and this negative pressure is stored. When the pressure reduction valve 34 is opened, the negative pressure stored in the pressure reduction tank 7 acts to reduce the pressure inside the space 15a of the motor 1 via the pressure reduction passage 27 and refrigerant passage 24 on the upstream side (oil tank 6 side) of the pressure reduction tank 7. Note that this space 15a is the space inside the motor 1 (inside the housing 15) to which refrigerant is supplied.

[0040] One end of refrigerant passage 28 is connected to refrigerant passage 21 upstream of first and second flow control valves 30, 31, and the other end is connected to refrigerant passage 24 downstream of oil tank 6 or the like, and is provided with a pressure sensor 44 that detects the pressure of the refrigerant and a check valve 39. When first and second flow control valves 30, 31 are closed, refrigerant passage 28 functions to allow refrigerant that did not flow through refrigerant passages 22, 23 to flow into refrigerant passage 24 via check valve (relief valve) 39. One end of refrigerant passage 29 is connected upstream of the connection point of refrigerant passage 21 to refrigerant passage 28, and the other end is connected downstream of the connection point of refrigerant passage 24 to refrigerant passage 28, and is provided with air-conditioner evaporator 8 and expansion valve 35 that decompresses the refrigerant.

[0041] Next, the specific configuration of the refrigerant passage 22 and the first flow rate adjustment valve 30 according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a schematic diagram for specifically explaining the refrigerant passage 22 and the first flow rate adjustment valve 30 according to this embodiment. Fig. 4 is a schematic diagram in which a plurality of refrigerant passages 22 and a plurality of first flow rate adjustment valves 30 are applied to a cross section of the rotating shaft 13 and the sliding bearing 14 in the motor 1.

[0042] As shown in FIG. 4, the refrigerant passage 22 has four refrigerant passages 22a to 22d that penetrate the plain bearing 14 to supply refrigerant to different circumferential positions in the gap between the outer circumferential surface of the rotating shaft 13 and the inner circumferential surface of the plain bearing 14. The refrigerant passages 22a to 22d are arranged at the same axial position and are equally spaced apart at 90-degree intervals along the circumferential direction. In FIG. 4, the refrigerant passage 22a is located at the lower right, the refrigerant passage 22b is located at the lower left, the refrigerant passage 22c is located at the upper left, and the refrigerant passage 22d is located at the upper right. In this case, the refrigerant passages 22a and 22b are located below the refrigerant passages 22c and 22d. In other words, the refrigerant passages 22a and 22b are located at the bottom of the plain bearing 14, and the refrigerant passages 22c and 22d are located at the top of the plain bearing 14. The refrigerant passages 22a and 22d are located further forward of the vehicle 200 than the refrigerant passages 22b and 22c. That is, the refrigerant passages 22a and 22d are provided in the front part of the plain bearing 14, and the refrigerant passages 22b and 22c are provided in the rear part of the plain bearing 14.

[0043] The first flow rate adjustment valve 30 has four first flow rate adjustment valves 30a to 30d so as to adjust the oil content of the refrigerant supplied from these four refrigerant passages 22a to 22d to the sliding bearing 14. These four first flow rate adjustment valves 30a to 30d are provided so as to connect the refrigerant passages 22a to 22d to the refrigerant passage 21 and the oil passage 25, respectively.

[0044] By using four refrigerant passages 22a-22d and four first flow control valves 30a-30d in this way, it is possible to supply refrigerant from different circumferential positions (four positions) to the gap between the rotating shaft 13 and the sliding bearing 14, and the oil content of the refrigerant supplied from these different positions can be changed respectively, that is, the oil content can be set in various ways depending on the circumferential position. Note that below, when there is no need to distinguish between the refrigerant passages 22a-22d, they will be simply referred to as the "refrigerant passage 22," and when there is no need to distinguish between the first flow control valves 30a-30d, they will be simply referred to as the "first flow control valve 30."

[0045] Next, the multiple refrigerant passages 22 provided in the axial direction in this embodiment will be described in detail with reference to Figure 5. Figure 5 is a schematic diagram showing a vertical cross section along the axial direction of a pair of sliding bearings 14 (14a, 14b), multiple refrigerant passages 22, etc.

[0046] 5, refrigerant passage 22 includes six sets of four refrigerant passages 22a-22d, with each of plain bearings 14a and 14b being provided with three sets of refrigerant passages 22a-22d. Specifically, plain bearing 14a is provided with a set of refrigerant passages 22a1, 22b1, 22c1, and 22d1, a set of refrigerant passages 22a2, 22b2, 22c2, and 22d2, and a set of refrigerant passages 22a3, 22b3, 22c3, and 22d3, spaced equally apart along the axial direction. Similarly, plain bearing 14b is provided with a set of refrigerant passages 22a4, 22b4, 22c4, and 22d4, a set of refrigerant passages 22a5, 22b5, 22c5, and 22d5, and a set of refrigerant passages 22a6, 22b6, 22c6, and 22d6, spaced equally apart along the axial direction.

[0047] The above-mentioned first flow rate adjustment valve 30 (not shown) is provided in each of the refrigerant passages 22a1 to 22d1, refrigerant passages 22a2 to 22d2, refrigerant passages 22a3 to 22d3, refrigerant passages 22a4 to 22d4, refrigerant passages 22a5 to 22d5, and refrigerant passages 22a6 to 22d6. Hereinafter, the first flow control valves 30 provided in the refrigerant passages 22a1 to 22d1, refrigerant passages 22a2 to 22d2, refrigerant passages 22a3 to 22d3, 22a4 to 22d4, refrigerant passages 22a5 to 22d5, and refrigerant passages 22a6 to 22d6 will be referred to as "first flow control valves 30a1 to 30d1," "first flow control valves 30a2 to 30d2," "first flow control valves 30a3 to 30d3," "first flow control valves 30a4 to 30d4," "first flow control valves 30a5 to 30d5," and "first flow control valves 30a6 to 30d6," respectively.

[0048] Furthermore, hereinafter, when there is no need to distinguish between refrigerant passages 22a1-22d1, refrigerant passages 22a2-22d2, refrigerant passages 22a3-22d3, 22a4-22d4, refrigerant passages 22a5-22d5, and refrigerant passages 22a6-22d6, they will be simply referred to as "refrigerant passages 22a-22d" or "refrigerant passage 22." Furthermore, when there is no need to distinguish between first flow rate adjustment valves 30a1-30d1, first flow rate adjustment valves 30a2-30d2, first flow rate adjustment valves 30a3-30d3, first flow rate adjustment valves 30a4-30d4, first flow rate adjustment valves 30a5-30d5, and first flow rate adjustment valves 30a6-30d6, they will be simply referred to as "first flow rate adjustment valves 30a-30d" or "first flow rate adjustment valve 30."

[0049] Next, the electrical configuration of the refrigerant circulation system 100 according to this embodiment will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the electrical configuration of the refrigerant circulation system 100 according to this embodiment.

[0050] 6, the refrigerant circulation system 100 has a control device 80 configured to perform various controls in the system. The control device 80 is configured by a computer including one or more processors 80a (typically a CPU) and memory 80b such as ROM and RAM that stores various programs interpreted and executed by the processor 80a (including basic control programs such as an OS and application programs that are started on the OS and realize specific functions) and various data.

[0051] In addition to the pressure sensors 40, 41, 44, oil pressure sensor 42, and oil level sensor 43, the refrigerant circulation system 100 also includes a motor rotation speed sensor 45 that detects the motor rotation speed of the motor 1 (the rotation speed of the rotor 11 and rotating shaft 13, which is synonymous with rotational speed), a vehicle speed sensor 46 that detects the speed of the vehicle 200 (vehicle speed), an acceleration sensor 47 that detects the acceleration acting on the vehicle 200, an accelerator position sensor 48 that detects the accelerator position corresponding to the amount of depression of the accelerator pedal of the vehicle 200, a bearing load sensor 49 that detects the load (radial load) applied in the radial direction to the plain bearing 14, an axial center position sensor 50 that detects the radial position (axial center position) of the axial center of the rotating shaft 13, and an external information acquisition device 51 that acquires external information about the vehicle 200. The axial center position sensor 50 may be configured to detect multiple axial center positions for each of the plain bearings 14a and 14b.

[0052] Specifically, the acceleration sensor 47 includes a plurality of sensors that detect accelerations occurring in the longitudinal, lateral, yaw, pitch, and roll directions of the vehicle 200. The external information acquisition device 51 also includes a camera that captures images of the surroundings of the vehicle 200, a radar (millimeter-wave radar, laser radar) that measures the positions and speeds of various objects present around the vehicle 200, an ultrasonic sensor, a navigation system, etc. The navigation system includes a positioning system (GPS system or gyro system) that detects the current position of the vehicle 200, map information, etc., and is capable of identifying roads (traveling paths), intersections, traffic signals, buildings, etc. present around the vehicle 200 from these.

[0053] Based on signals from these sensors 40 to 50 and the external information acquisition device 51, the control device 80 supplies control signals to the motor 1, the compressor 3, the first flow rate adjustment valves 30a to 30d (30a1 to 30d1, 30a2 to 30d2, 30a3 to 30d3, 30a4 to 30d4, 30a5 to 30d5, 30a6 to 30d6), the second flow rate adjustment valve 31, the oil pump 32, the pressure reducing valve 34, and the oil level warning light 60. The oil level warning light 60 is a lamp that warns that the level of oil stored in the oil tank 6 (detected by the oil level sensor 43) is below a predetermined value.

[0054] In this embodiment, when a stopped motor 1 is started, the control device 80 controls the first flow rate adjustment valve 30 so that the oil content of the refrigerant supplied from the refrigerant passage 22 to the sliding bearing 14 is higher than when the motor 1 is operating. In this case, the control device 80 controls the first flow rate adjustment valves 30a, 30b provided in the refrigerant passages 22a, 22b so as to increase the oil content particularly from the refrigerant passages 22a, 22b that are provided among the refrigerant passages 22a to 22d so as to supply refrigerant to the lower part of the sliding bearing 14, typically so that the oil content in the refrigerant passages 22a, 22b is approximately 100%.

[0055] Furthermore, when an operating motor 1 is stopped, the control device 80 controls the first flow rate adjustment valve 30 so as to increase the oil content in the refrigerant supplied from the refrigerant passage 22 to the sliding bearing 14, just as it does when the motor 1 is started. In particular, the control device 80 controls the first flow rate adjustment valves 30a, 30b so as to increase the oil content in the refrigerant supplied from refrigerant passages 22a, 22b that are provided to supply refrigerant to the lower part of the sliding bearing 14, typically so that the oil content in the refrigerant passages 22a, 22b is approximately 100%.

[0056] Furthermore, in this embodiment, when the motor 1 is operating, the control device 80 controls each of the first flow control valves 30a to 30d so that the oil content from the refrigerant passages 22a1 to 22d1, 22a3 to 22d3 provided at both axial ends of the sliding bearing 14a, and the oil content from the refrigerant passages 22a4 to 22d4, 22a6 to 22d6 provided at both axial ends of the sliding bearing 14b are greater than the oil content from the other refrigerant passages 22a2 to 22d2, 22a5 to 22d5. Typically, the control device 80 controls each of the first flow rate adjustment valves 30a to 30d so that the oil content from the refrigerant passages 22a1 to 22d1, 22a3 to 22d3, 22a4 to 22d4, and 22a6 to 22d6 is approximately 100%, and the oil content from the refrigerant passages 22a2 to 22d2 and 22a5 to 22d5 is approximately 0%.

[0057] The control performed when starting, operating, and stopping the motor 1 as described above will be referred to as "basic control" below as appropriate. In this embodiment, in addition to this basic control, the control device 80 also performs control (hereinafter referred to as "contact avoidance control") to avoid contact between the rotating shaft 13 and the plain bearing 14 when the rotating shaft 13 of the motor 1 is tilted due to the state of the vehicle 200 or the like, and there is a possibility that the rotating shaft 13 will come into contact with the plain bearing 14.

[0058] As this contact avoidance control, the control device 80 controls each of the first flow rate adjustment valves 30a-30d so that the oil content from one or more refrigerant passages 22 provided at locations corresponding to positions among the multiple refrigerant passages 22 where the rotating shaft 13 may come into contact with the sliding bearing 14 is greater than the oil content from the other refrigerant passages 22. Typically, the control device 80 controls each of the first flow rate adjustment valves 30a-30d so that the oil content from this one or more refrigerant passages 22 is approximately 100% and the oil content from the other refrigerant passages 22 is approximately 0%.

[0059] Furthermore, in such contact avoidance control, the control device 80 determines the possibility that the rotating shaft 13 of the motor 1 will come into contact with the plain bearing 14 based on the axial position of the rotating shaft 13 detected by the axial position sensor 50, the acceleration in the longitudinal, lateral, yaw, pitch, and roll directions detected by the acceleration sensor 47, and external information about the vehicle 200 acquired by the external information acquisition device 51. Essentially, the control device 80 determines a state in which the rotating shaft 13 is likely to come into contact with the plain bearing 14 (i.e., the state before the rotating shaft 13 comes into contact with the plain bearing 14) rather than determining a state in which the rotating shaft 13 actually comes into contact with the plain bearing 14. Furthermore, the control device 80 identifies a position at which the rotating shaft 13 may come into contact with the plain bearing 14, and also identifies a refrigerant passage 22 provided at a location among the refrigerant passages 22a to 22d that corresponds to this identified position. The control device 80, together with the axial position sensor 50, the acceleration sensor 47, and the external information acquisition device 51, constitute a "contact determination device" according to the present invention.

[0060] [Control content] Next, the control performed by the control device 80 of the refrigerant circulation system 100 in this embodiment will be described in detail. First, basic control at start-up and stop according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a schematic diagram of a cross section of the rotating shaft 13 and the sliding bearing 14 (including the refrigerant passages 22a to 22d) in the motor 1.

[0061] As shown in the left diagram of Fig. 7, when the motor 1 is stopped, the supply of refrigerant from the refrigerant passages 22a-22d into the sliding bearing 14 is stopped, and the outer peripheral surface of the lower part of the rotating shaft 13 is in contact with the inner peripheral surface of the lower part of the sliding bearing 14 due to its own weight. When the stopped motor 1 is started, specifically just before the motor 1 starts (that is, before the motor rotation speed begins to increase after a motor start request is issued), in this embodiment, as shown in the right diagram of Fig. 7, the control device 80 controls the first flow control valves 30a, 30b provided in the refrigerant passages 22a, 22b provided below the sliding bearing 14 to increase the oil content from these refrigerant passages 22a, 22b. In particular, the control device 80 controls the first flow control valves 30a, 30b to make the oil content in the refrigerant passages 22a, 22b 100%. As a result, when motor 1 starts, the refrigerant (refrigerant with a 100% oil content, i.e., oil itself) sprayed from refrigerant passages 22a, 22b, in other words, static pressure caused by the refrigerant, acts from below on rotating shaft 13, causing rotating shaft 13 to float against its own weight from the inner circumferential surface of the lower part of sliding bearing 14 (arrow A2). Therefore, the load capacity of sliding bearing 14 can be adequately ensured when motor 1 starts.

[0062] Next, when the operating motor 1 is stopped, specifically immediately before the motor 1 is stopped (i.e., before the motor rotation speed drops to 0), in this embodiment, as shown in the right diagram of FIG. 7 , the control device 80 controls the first flow control valves 30a and 30b so that the oil content from the refrigerant passages 22a and 22b provided below the sliding bearing 14 becomes 100%, as in the case of starting the motor 1 described above. As a result, when the motor 1 is stopped, a high-viscosity refrigerant is supplied below the rotating shaft 13, thereby maintaining the floating state of the rotating shaft 13 (arrow A2). Therefore, the floating state of the rotating shaft 13 can be maintained until the rotation of the rotating shaft 13 completely stops, making it possible to accurately prevent the rotating shaft 13 from coming into contact with the sliding bearing 14.

[0063] Next, basic control during normal operation of the motor 1 according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing a vertical cross section along the axial direction of the pair of sliding bearings 14 (14a, 14b), the plurality of refrigerant passages 22, etc.

[0064] As shown in FIG. 8, in this embodiment, when the motor 1 is operating (i.e., while the vehicle 200 is running), the control device 80 controls each of the first flow control valves 30a to 30d so that the oil content from the refrigerant passages 22a1 to 22d1 and 22a3 to 22d3 provided at both axial ends of the sliding bearing 14a and the oil content from the refrigerant passages 22a4 to 22d4 and 22a6 to 22d6 provided at both axial ends of the sliding bearing 14b are greater than the oil content from the other refrigerant passages 22a2 to 22d2 and 22a5 to 22d5. Typically, the control device 80 controls each of the first flow rate adjustment valves 30a to 30d so that the oil content from the refrigerant passages 22a1 to 22d1, 22a3 to 22d3, 22a4 to 22d4, and 22a6 to 22d6 is approximately 100%, and the oil content from the refrigerant passages 22a2 to 22d2 and 22a5 to 22d5 is approximately 0%.

[0065] In this way, while the motor 1 is operating, a high-viscosity refrigerant is supplied to both axial ends of the sliding bearing 14, while a low-viscosity refrigerant is supplied to the axial center of the sliding bearing 14. This makes it possible to form a viscosity distribution that can handle loads applied diagonally to the axial direction, and also makes it possible to keep the average viscosity of the entire sliding bearing 14 relatively low, thereby reducing the lubrication resistance (friction) caused by the oil.

[0066] Next, contact avoidance control of the motor 1 according to this embodiment will be described with reference to Figures 9 to 11. Figures 9 to 11 are schematic diagrams showing vertical cross sections along the axial direction of the pair of sliding bearings 14 (14a, 14b), the plurality of refrigerant passages 22, etc.

[0067] First, contact avoidance control during yawing according to this embodiment will be described with reference to Figure 9. When vehicle 200 yawing significantly (for example, when turning a sharp curve), the rotational inertia causes rotating shaft 13 to tilt and move radially (particularly in the front-to-rear direction) (arrow A3). At this time, in this embodiment, if control device 80 determines that rotating shaft 13 may come into contact with sliding bearing 14 based on the shaft center position detected by shaft center position sensor 50, the acceleration detected by acceleration sensor 47, and external information acquired by external information acquisition device 51, then control first flow rate adjustment valves 30a-30d to adjust the oil content of each of refrigerant passages 22a-22d to avoid this contact.

[0068] Specifically, as shown in FIG. 9, the control device 80 controls each of the first flow control valves 30a to 30d depending on the tilt direction of the rotating shaft 13 due to yawing so that the oil content from the refrigerant passages 22a1, 22d1, 22a2, 22d2 located on the front side and distal to the rotor 11 among the multiple refrigerant passages 22 provided in one plain bearing 14a, and the oil content from the refrigerant passages 22b5, 22c5, 22b6, 22c6 located on the rear side and distal to the rotor 11 among the multiple refrigerant passages 22 provided in the other plain bearing 14b, is greater than the oil content from the other refrigerant passages 22. Typically, control device 80 controls each of first flow control valves 30a-30d so that the oil content from refrigerant passages 22a1, 22d1, 22a2, 22d2, 22b5, 22c5, 22b6, and 22c6 is approximately 100%, and the oil content from the other refrigerant passages 22 is approximately 0%. This makes it possible to locally increase the viscosity of the refrigerant near the position of sliding bearing 14 with which rotating shaft 13 may come into contact during large yawing of vehicle 200, that is, to locally increase the load capacity. This makes it possible to reliably avoid contact between rotating shaft 13 and sliding bearing 14 due to large yawing.

[0069] Next, contact avoidance control during rolling according to this embodiment will be described with reference to Fig. 10. When vehicle 200 rolls significantly (for example, when turning a sharp curve), the rotational inertia causes rotating shaft 13 to tilt and move radially (particularly in the up-down direction) (arrow A4). At this time, in this embodiment, if control device 80 determines that rotating shaft 13 may come into contact with sliding bearing 14 based on the shaft center position detected by shaft center position sensor 50, the acceleration detected by acceleration sensor 47, and external information acquired by external information acquisition device 51, then control first flow rate adjustment valves 30a-30d to adjust the oil content of each of refrigerant passages 22a-22d to avoid this contact.

[0070] Specifically, as shown in FIG. 10, the control device 80 controls each of the first flow control valves 30a to 30d depending on the tilt direction of the rotating shaft 13 due to rolling so that the oil content from the refrigerant passages 22c1, 22d1, 22c2, 22d2 located on the upper side and distal to the rotor 11 among the multiple refrigerant passages 22 provided in one plain bearing 14a, and the oil content from the refrigerant passages 22a5, 22b5, 22a6, 22b6 located on the lower side and distal to the rotor 11 among the multiple refrigerant passages 22 provided in the other plain bearing 14b, is greater than the oil content from the other refrigerant passages 22. Typically, control device 80 controls each of first flow control valves 30a-30d so that the oil content from refrigerant passages 22c1, 22d1, 22c2, 22d2, 22a5, 22b5, 22a6, and 22b6 is approximately 100%, and the oil content from the other refrigerant passages 22 is approximately 0%. This makes it possible to locally increase the viscosity of the refrigerant near the position of sliding bearing 14 with which rotating shaft 13 may come into contact when vehicle 200 rolls significantly, that is, to locally increase the load capacity. This makes it possible to reliably prevent contact between rotating shaft 13 and sliding bearing 14 due to significant rolling.

[0071] Next, contact avoidance control during pitching according to this embodiment will be described with reference to Fig. 11. When vehicle 200 pitches significantly (for example, when vehicle 200 collides or is thrust up from the road surface), a bending load (arrows A51 and A52) is generated in rotor 11, causing rotating shaft 13 to tilt and move radially (particularly in the up-down direction) (arrows A61 and A62). In this case, in this embodiment, if control device 80 determines that rotating shaft 13 may come into contact with sliding bearing 14 based on the axial position detected by axial position sensor 50, the acceleration detected by acceleration sensor 47, and external information acquired by external information acquisition device 51, then control first flow control valves 30a-30d to adjust the oil content of each of refrigerant passages 22a-22d to avoid this contact.

[0072] Specifically, as shown in FIG. 11, the control device 80 controls each of the first flow control valves 30a to 30d in accordance with the tilt direction of the rotating shaft 13 due to pitching so that the oil content from refrigerant passages 22c1, 22d1, 22c2, 22d2 located on the upper side and distal to the rotor 11 and refrigerant passages 22a2, 22b2, 22a3, 22b3 located on the lower side and proximal to the rotor 11 among the multiple refrigerant passages 22 provided in one plain bearing 14a, and the oil content from refrigerant passages 22c5, 22d5, 22c6, 22d6 located on the upper side and distal to the rotor 11 and refrigerant passages 22a4, 22b4, 22a5, 22b5 located on the lower side and proximal to the rotor 11 among the multiple refrigerant passages 22 provided in the other plain bearing 14b, is greater than the oil content from the other refrigerant passages 22. Typically, control device 80 controls each of first flow control valves 30a-30d so that the oil content from refrigerant passages 22c1, 22d1, 22a2, 22b2, 22c2, 22d2, 22a3, 22b3, 22a4, 22b4, 22a5, 22b5, 22c5, 22d5, 22c6, and 22d6 is approximately 100% and the oil content from the other refrigerant passages 22 is approximately 0%. This makes it possible to locally increase the viscosity of the refrigerant near the position of sliding bearing 14 with which rotating shaft 13 may come into contact during large pitching of vehicle 200, thereby locally increasing the load capacity. This effectively prevents contact between rotating shaft 13 and sliding bearing 14 due to large pitching.

[0073] Next, a flowchart showing basic control according to this embodiment will be described with reference to Fig. 12. This flow is repeatedly executed at a predetermined cycle by the control device 80. In detail, the processor 80a in the control device 80 reads a program stored in the memory 80b and executes the program, thereby realizing the control according to this flow.

[0074] First, in step S10, the control device 80 acquires various pieces of information from the above-mentioned sensors 40 to 50 and the external information acquisition device 51 (FIG. 6), etc. Then, the control device 80 proceeds to step S11, where it determines whether the oil level detected by the oil level sensor 43 is equal to or greater than a predetermined value. As a result, if the control device 80 does not determine that the oil level is equal to or greater than the predetermined value (step S11: No), that is, if the oil level is less than the predetermined value, it proceeds to step S12, where it turns on the oil level warning light 60.

[0075] The control device 80 then proceeds to step S13, where it determines whether the motor 1 is not stopped based on the motor rotation speed detected by the motor rotation speed sensor 45, etc. As a result, if the control device 80 determines that the motor 1 is not stopped (step S13: Yes), that is, if the motor 1 is operating, it proceeds to step S14, where it stops the motor 1. Thereafter, the control device 80 ends the control related to this flow. On the other hand, if the control device 80 does not determine that the motor 1 is not stopped (step S13: No), that is, if the motor 1 is already stopped, it ends the control related to this flow.

[0076] On the other hand, if the control device 80 determines in step S11 that the oil level is equal to or higher than the predetermined value (step S11: Yes), the process proceeds to step S15. In step S15, the control device 80 determines whether the motor 1 is stopped based on the motor rotation speed detected by the motor rotation speed sensor 45, etc. If the control device 80 determines that the motor 1 is stopped (step S15: Yes), the process proceeds to step S16, where it determines whether a motor start request has been made based on the start switch of the vehicle 200 and the accelerator opening detected by the accelerator opening sensor 48, etc. If the control device 80 determines that a motor start request has been made (step S16: Yes), the process proceeds to step S17. In this case, the control device 80 sets a target rotation speed according to the accelerator opening, etc. On the other hand, if the control device 80 does not determine that a motor start request has been made (step S16: No), the process terminates the control of this flow.

[0077] In step S17, the control device 80 starts the oil pump 32 and the compressor 3. Then, the control device 80 proceeds to step S18, where it controls the first flow control valves 30a and 30b provided in the refrigerant passages 22a and 22b so that the oil content of the refrigerant supplied from these refrigerant passages 22a and 22b becomes 100%. Thereafter, in step S19, the control device 80 controls the first flow control valves 30c and 30d so that the oil content of the refrigerant supplied from the refrigerant passages 22c and 22d becomes 100%. Then, the control device 80 proceeds to step S20, where it starts the motor 1.

[0078] Next, the control device 80 proceeds to step S21 and determines the aperture of each of the first flow control valves 30a-30d. For example, the control device 80 determines the required viscosity of the refrigerant supplied to the sliding bearing 14 of the motor 1 (i.e., the required oil content) based on the target rotation speed of the motor 1 and determines the aperture of each of the valves 30a-30d according to this required viscosity. Basically, the control device 80 sets a smaller required viscosity as the target motor rotation speed increases. The control device 80 also determines the aperture of each of the valves 30a-30d so that the oil content from the refrigerant passages 22a1-22d1, 22a3-22d3, 22a4-22d4, and 22a6-22d6 provided at both axial ends of each of the sliding bearings 14a, 14b is greater than the oil content from the other refrigerant passages 22. Then, the control device 80 proceeds to step S22, controls each of the first flow rate adjustment valves 30a to 30d so that the opening degree is set to the degree determined in step S21, and then ends the control related to this flow.

[0079] On the other hand, if the control device 80 does not determine in step S15 that the motor 1 is stopped (step S15: No), that is, if the motor 1 is operating, the control device 80 proceeds to step S23. In step S23, the control device 80 determines whether there is a request to change the motor rotation speed based on the accelerator opening detected by the accelerator opening sensor 48, etc. Note that a request to change the motor rotation speed also includes a request to stop the motor 1. If the control device 80 determines in step S23 that there is a request to change the motor rotation speed (step S23: Yes), the control device 80 proceeds to step S24, and if it does not determine that there is a request to change the motor rotation speed (step S23: No), the control related to this flow ends.

[0080] In step S24, the control device 80 determines the aperture of each of the first flow control valves 30a-30d. For example, the control device 80 determines the required viscosity of the refrigerant (i.e., the required oil content) supplied to the sliding bearing 14 of the motor 1 based on factors such as the motor rotation speed to be changed (target rotation speed), and determines the aperture of each of the valves 30a-30d according to this required viscosity. Basically, the control device 80 sets a lower required viscosity as the motor rotation speed increases. The control device 80 also determines the aperture of each of the valves 30a-30d so that the oil content from the refrigerant passages 22a1-22d1, 22a3-22d3, 22a4-22d4, and 22a6-22d6 provided at both axial ends of each of the sliding bearings 14a, 14b is greater than the oil content from the other refrigerant passages 22. The control device 80 then proceeds to step S25, where it controls each of the first flow rate adjustment valves 30a-30d so as to set the opening degree determined in step S24. The control device 80 then proceeds to step S26, where it controls the motor 1 to change the motor rotation speed, and then ends the control related to this flow.

[0081] Next, a flowchart showing collision avoidance control according to this embodiment will be described with reference to Fig. 13. This flow is also repeatedly executed at a predetermined cycle by the control device 80. In detail, the processor 80a in the control device 80 reads out a program stored in the memory 80b and executes the program, thereby realizing the control related to this flow.

[0082] First, in step S30, the control device 80 acquires various pieces of information from the above-mentioned sensors 40 to 50 and the external information acquisition device 51 (FIG. 6), etc. Then, the control device 80 proceeds to step S31, and determines whether or not there is a possibility that the rotating shaft 13 of the motor 1 will come into contact with the sliding bearing 14, based on the shaft center position detected by the shaft center position sensor 50, the acceleration detected by the acceleration sensor 47, and the external information acquired by the external information acquisition device 51.

[0083] In one example, the control device 80 calculates the gap distance at the position where the gap between the outer circumferential surface of the rotating shaft 13 and the inner circumferential surface of the sliding bearing 14 is smallest, based on the shaft center position detected by the shaft center position sensor 50, and if this distance is less than a threshold value, determines that there is a possibility that the rotating shaft 13 will come into contact with the sliding bearing 14. In this case, it is preferable to use multiple shaft center position sensors 50 (preferably provided corresponding to the multiple refrigerant passages 22 provided in the axial direction) provided to detect multiple shaft center positions in the axial direction, and determine the gap distances determined from each shaft center position sensor 50. In another example, the control device 80 determines that there is a possibility that the rotating shaft 13 will come into contact with the sliding bearing 14 if the acceleration in the fore-and-aft direction, lateral direction, yaw direction, roll direction, or pitch direction of the vehicle 200 detected by the acceleration sensor 47 (including multiple sensors) is equal to or greater than a threshold value. In yet another example, when external information acquired by the external information acquisition device 51 (typically a camera or radar) indicates that the vehicle 200 may collide with an obstacle (another vehicle, a step, etc.) on the travel path, the control device 80 determines that there is a possibility that the rotating shaft 13 will come into contact with the plain bearing 14. In yet another example, when external information acquired by the external information acquisition device 51 (typically a navigation system) indicates a travel path on which acceleration equal to or greater than a threshold value may occur due to the travel of the vehicle 200 (acceleration in the yaw direction, roll direction, or pitch direction due to turning, etc.), the control device 80 determines that there is a possibility that the rotating shaft 13 will come into contact with the plain bearing 14.

[0084] If the control device 80 determines that there is no possibility that the rotating shaft 13 will come into contact with the plain bearing 14 (step S31: Yes), it proceeds to step S32 and controls the first flow control valves 30a-30d as usual. Specifically, the control device 80 performs the basic control described above. Essentially, the control device 80 determines the required viscosity (required content) of the refrigerant to be supplied to the plain bearing 14 based on the target rotation speed of the motor 1, etc., determines the opening degree of each of the first flow control valves 30a-30d according to this required viscosity, and controls each of the valves 30a-30d so that the determined opening degree is set. Thereafter, the control related to this flow ends.

[0085] On the other hand, if the control device 80 has not determined that there is no possibility that the rotating shaft 13 will come into contact with the plain bearing 14 (step S31: No), that is, if there is a possibility that the rotating shaft 13 will come into contact with the plain bearing 14, the process proceeds to step S33. In step S33, the control device 80 controls each of the first flow control valves 30a-30d so that the oil content from one or more refrigerant passages 22 provided at locations among the multiple refrigerant passages 22 that correspond to positions where the rotating shaft 13 may come into contact with the plain bearing 14 is greater than the oil content from the other refrigerant passages 22. Specifically, the control device 80 controls each of the first flow control valves 30a-30d so that the oil content from this one or more refrigerant passages 22 is approximately 100% and the oil content from the other refrigerant passages 22 is approximately 0%.

[0086] Here, in one example, the control device 80 identifies a position where the rotating shaft 13 may come into contact with the plain bearing 14, based on the shaft position detected by the shaft position sensor 50, and identifies a refrigerant passage 22 provided at a location close to this identified position among the multiple refrigerant passages 22. In another example, the control device 80 may identify a position where the rotating shaft 13 may come into contact with the plain bearing 14, and a refrigerant passage 22 provided at a location close to this position, based on the acceleration detected by the acceleration sensor 47 and external information acquired by the external information acquisition device 51, from the direction of acceleration occurring in the vehicle 200, etc.

[0087] After step S33, the control device 80 returns to step S31. As a result, while there is a possibility that the rotating shaft 13 will come into contact with the sliding bearing 14 (step S31: No), the control device 80 repeatedly executes the control of step S33 to avoid this contact.

[0088] [Action and effect] Next, the operation and effects of the refrigerant circulation system 100 according to this embodiment will be described.

[0089] In this embodiment, a refrigerant circulation system 100 that circulates a refrigerant in which CO2 contains oil (CO2 refrigerant) 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 motor 1 that includes a pair of plain bearings 14 (14a, 14b) that are lubricated using a liquid refrigerant compressed by the compressor 3 and support the rotating shaft 13, a refrigerant passage 22 that supplies refrigerant to the plain bearing 14 of the motor 1, a first flow control valve 30 that is configured to adjust the oil content of the refrigerant supplied from the refrigerant passage 22 to the plain bearing 14, an acceleration sensor 47, a shaft center position sensor 50, an external information acquisition device 51, and a control device 80 that are configured to determine the possibility that the rotating shaft 13 will come into contact with the plain bearing 14 in the motor 1, The refrigerant passage 22 includes a plurality of refrigerant passages 22a to 22d arranged to supply refrigerant to a plurality of axial positions in each of the pair of plain bearings 14a, 14b, and the first flow control valve 30 includes a plurality of first flow control valves 30a to 30d arranged to adjust the oil content in the refrigerant supplied from these refrigerant passages 22a to 22d, respectively, and when it is determined that there is a possibility that the rotating shaft 13 will come into contact with the plain bearing 14, the control device 80 controls each of the first flow control valves 30a to 30d so that the oil content from one or more refrigerant passages 22 arranged at locations among the plurality of refrigerant passages 22 that correspond to positions where the rotating shaft 13 may come into contact with the plain bearing 14 is greater than the oil content from the other refrigerant passages 22.

[0090] According to this embodiment, when the rotating shaft 13 of the motor 1 tilts due to the state of the vehicle 200 or the like, and there is a possibility that the rotating shaft 13 will come into contact with the sliding bearing 14, the control device 80 increases the oil content in one or more refrigerant passages 22 provided in locations corresponding to the positions of potential contact, thereby making it possible to locally increase the viscosity of the refrigerant in the sliding bearing 14 near these refrigerant passages 22. In other words, it is possible to locally increase the load capacity near the positions where the rotating shaft 13 may come into contact with the sliding bearing 14. This makes it possible to reliably avoid contact between the rotating shaft 13 and the sliding bearing 14.

[0091] Furthermore, in this embodiment, a plurality of refrigerant passages 22 are provided along the axial direction, and a plurality of refrigerant passages 22 are provided along the circumferential direction of the plain bearing 14. This makes it possible to selectively increase the local load capacity at various positions within the plain bearing 14 in the axial and circumferential directions.

[0092] Furthermore, in this embodiment, when yawing occurs in the vehicle 200, the one or more refrigerant passages 22 that are controlled to increase the oil content include the refrigerant passage 22 that is located at the front of the multiple refrigerant passages 22 provided in one of the pair of plain bearings 14, and the refrigerant passage 22 that is located at the rear of the multiple refrigerant passages 22 provided in the other of the pair of plain bearings 14. This makes it possible to locally increase the viscosity of the refrigerant near the position of the plain bearing 14 with which the rotating shaft 13 may come into contact during large yawing in the vehicle 200, thereby locally increasing the load capacity. This makes it possible to reliably avoid contact between the rotating shaft 13 and the plain bearing 14 due to large yawing.

[0093] Furthermore, in this embodiment, when rolling occurs in the vehicle 200, the one or more refrigerant passages 22 that are controlled to increase the oil content include the refrigerant passage 22 that is located at the top of the multiple refrigerant passages 22 provided in one of the pair of plain bearings 14, and the refrigerant passage 22 that is located at the bottom of the multiple refrigerant passages 22 provided in the other of the pair of plain bearings 14. This makes it possible to locally increase the viscosity of the refrigerant near the position of the plain bearing 14 with which the rotating shaft 13 may come into contact when the vehicle 200 rolls significantly, that is, to locally increase the load capacity. This effectively prevents contact between the rotating shaft 13 and the plain bearing 14 due to significant rolling.

[0094] Furthermore, in this embodiment, when pitching occurs in the vehicle 200, the one or more refrigerant passages 22 that are controlled to increase the oil content include, in each of the pair of sliding bearings 14, the upper refrigerant passage 22 among the multiple refrigerant passages 22 provided on one axial side, and the lower refrigerant passage 22 among the multiple refrigerant passages 22 provided on the other axial side. This makes it possible to locally increase the viscosity of the refrigerant near the position of the sliding bearing 14 with which the rotating shaft 13 may come into contact during large pitching in the vehicle 200, thereby locally increasing the load capacity. This effectively prevents contact between the rotating shaft 13 and the sliding bearing 14 due to large pitching.

[0095] Furthermore, in this embodiment, the control device 80 controls each of the first flow control valves 30a to 30d so that the oil content from one or more of the refrigerant passages 22 is approximately 100% and the oil content from the other refrigerant passages is approximately 0%. This effectively increases the load capacity near the position where the rotating shaft 13 may come into contact with the sliding bearing 14.

[0096] Furthermore, in this embodiment, the possibility of the rotating shaft 13 coming into contact with the plain bearing 14 is determined based on the shaft center position detected by the shaft center position sensor 50, the acceleration detected by the acceleration sensor 47, and external information acquired by the external information acquisition device 51. This makes it possible to accurately determine the possibility of the rotating shaft 13 coming into contact with the plain bearing 14.

[0097] In this embodiment, the refrigerant circulation system 100 further includes an oil passage 25 that supplies oil to the refrigerant passage 22, and an oil tank 6 that is connected to the oil passage 25 and stores the oil, and the oil tank 6 is configured to separate the oil contained in the refrigerant and store the oil. This allows the oil to be appropriately recovered from the refrigerant and stored in the oil tank 6.

[0098] [Variations] In the above-described embodiment, the refrigerant circulation system 100 uses six sets of four refrigerant passages 22a-22d. However, in a modified example, a set of three or less or five or more refrigerant passages 22 may be used, or four sets or eight or more sets (eight sets, ten sets, twelve sets, etc.) of refrigerant passages 22 may be used. A first flow control valve 30 may be provided for each of the plurality of refrigerant passages 22. In another modified example, the system is not limited to providing a plurality of refrigerant passages 22 (for example, sets of four refrigerant passages 22a-22d) along the axial direction, and a plurality of single refrigerant passages 22 may be provided along the axial direction. In this case, it is preferable that the refrigerant passages 22 provided at different axial positions are also arranged at different circumferential positions. [Explanation of symbols]

[0099] 1 motor 3 Compressor 5 Heat exchanger 6. Oil Tank 7. Decompression Tank 11 rotor 12 Stator 13 Rotation axis 14(14a, 14b) Plain bearing 21, 23, 24 Refrigerant passages 22(22a~22d) Refrigerant passage 25 Oil passage 27 Decompression Passage 30 (30a-30d) First flow control valve (oil content control valve) 31 Second flow control valve 32 Oil pump 34 Pressure reducing valve 43 Oil level sensor 47 Accelerometer 50 Shaft position sensor 51 External information acquisition device 80 Control device 100 Refrigerant Circulation System 200 vehicles

Claims

1. CO 2 A refrigerant circulation system that circulates a refrigerant containing oil in a a compressor that compresses the refrigerant; a motor including a rotor, a stator, a rotating shaft connected to the rotor, and a pair of sliding bearings that support the rotating shaft and are lubricated using the liquid refrigerant compressed by the compressor; a refrigerant passage that supplies the refrigerant to the sliding bearing of the motor; an oil content adjustment valve configured to adjust the oil content of the refrigerant supplied from the refrigerant passage to the sliding bearing; a contact determination device configured to determine the possibility of the rotating shaft of the motor coming into contact with the sliding bearing; a control device configured to control the oil content adjustment valve; and a plurality of the refrigerant passages are provided in each of the pair of sliding bearings so as to supply the refrigerant to a plurality of positions in the axial direction, a plurality of the oil content adjustment valves are provided to adjust the oil content of the refrigerant supplied from the plurality of refrigerant passages, respectively; The control device is configured to, when it is determined by the contact determination device that there is a possibility that the rotating shaft will come into contact with the plain bearing, control each of the plurality of oil content adjustment valves so that the oil content from one or more refrigerant passages provided at locations among the plurality of refrigerant passages that correspond to positions where the rotating shaft may come into contact with the plain bearing is greater than the oil content from other refrigerant passages other than the one or more refrigerant passages. A refrigerant circulation system.

2. The refrigerant circulation system according to claim 1 , wherein a plurality of the refrigerant passages are provided along the axial direction and a plurality of the refrigerant passages are provided along the circumferential direction of the sliding bearing.

3. The refrigerant circulation system is mounted on a vehicle, 3. The refrigerant circulation system according to claim 1 or 2, wherein the one or more refrigerant passages controlled by the control device to increase the oil content include, when yawing occurs in the vehicle, a refrigerant passage located at the front of multiple refrigerant passages provided in one of the pair of plain bearings, and a refrigerant passage located at the rear of multiple refrigerant passages provided in the other of the pair of plain bearings.

4. The refrigerant circulation system is mounted on a vehicle, 3. The refrigerant circulation system according to claim 1 or 2, wherein the one or more refrigerant passages controlled by the control device to increase the oil content include, when rolling occurs in the vehicle, a refrigerant passage located at an upper position among multiple refrigerant passages provided in one of the pair of plain bearings, and a refrigerant passage located at a lower position among multiple refrigerant passages provided in the other of the pair of plain bearings.

5. The refrigerant circulation system is mounted on a vehicle, 3. The refrigerant circulation system according to claim 1 or 2, wherein the one or more refrigerant passages controlled by the control device to increase the oil content include, in each of the pair of sliding bearings, a refrigerant passage located at an upper side among multiple refrigerant passages provided on one axial side, and a refrigerant passage located at a lower side among multiple refrigerant passages provided on the other axial side, when pitching occurs in the vehicle.

6. 3. The refrigerant circulation system according to claim 1, wherein the control device is configured to control each of the plurality of oil content adjustment valves so that the oil content from the one or more refrigerant passages is approximately 100% and the oil content from the other refrigerant passages is approximately 0%.

7. 3. The refrigerant circulation system according to claim 1, wherein the contact determination device includes a shaft center position sensor that detects a shaft center position of the rotating shaft, and is configured to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on an output of the shaft center position sensor.

8. The refrigerant circulation system is mounted on a vehicle, The contact determination device is configured to include one or more sensors that detect acceleration occurring in at least one of a longitudinal direction, a lateral direction, a yaw direction, a pitch direction, and a roll direction in the vehicle, and to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on the output of the one or more sensors. The refrigerant circulation system according to claim 1 or 2.

9. The refrigerant circulation system is mounted on a vehicle, The contact determination device is configured to include an external information acquisition device that acquires external information about the vehicle, and to determine the possibility of the rotating shaft coming into contact with the sliding bearing based on the external information acquired by the external information acquisition device. The refrigerant circulation system according to claim 1 or 2.

10. 3. The refrigerant circulation system according to claim 1, further comprising: an oil passage that supplies the oil to the refrigerant passage; and an oil tank connected to the oil passage that stores the oil, wherein the oil tank is configured to separate the oil contained in the refrigerant and store the oil.

11. When the refrigerant passage is defined as a first refrigerant passage, the refrigerant circulation system further includes a second refrigerant passage that communicates with the first refrigerant passage and allows the refrigerant from the compressor to flow into the first refrigerant passage, The oil content adjustment valve is in communication with the first refrigerant passage, the second refrigerant passage, and the oil passage, and thereby, by controlling the oil content adjustment valve, it is possible to change the mixing ratio of the refrigerant from the second refrigerant passage and the oil from the oil passage, and adjust the oil content in the refrigerant supplied from the first refrigerant passage to the sliding bearing. The refrigerant circulation system according to claim 10.

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