Motor system

Abstract

In a motor system having a motor, a sliding bearing, and a sealing member, the increase in stirring resistance within the motor and the protection of the sealing member are achieved. [Solution] The motor system 200 includes a motor 1, a sliding bearing 15 that supports the motor's rotating shaft 13, an oil passage 27a and a refrigerant passage 22b for supplying oil and a refrigerant (CO2 refrigerant) into the sliding bearing to lubricate the sliding bearing, a refrigerant passage 23 for supplying a refrigerant into the motor to cool the motor, and a sealing member 18 to which oil is supplied and which uses the oil to seal the gap between the portion of the rotating shaft extending from the motor housing 14 to the outside and the housing. The oil passage 27a is configured to supply oil to a position in the sliding bearing that is on the sealing member side in the axial direction, and the refrigerant passage 22b is configured to supply refrigerant to a position in the sliding bearing that is on the rotor side in the axial direction.

Description

Technical Field

[0001] The present invention relates to a motor system having a motor and a sliding bearing that supports the rotating shaft of the motor.

Background Art

[0002] Conventionally, sliding bearings configured to be lubricated by a fluid (working fluid) such as oil and to support a rotating shaft are known. This type of technology is described in, for example, Patent Document 1. Specifically, Patent Document 1 describes a technology in which an auxiliary bearing as a rolling bearing is made to function as a sliding bearing (fluid bearing) by supplying a refrigerant (fluid) to the gap between its inner ring and the rotating shaft, thereby mitigating the influence of frictional heat generated between the auxiliary bearing and the rotating shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the inventors of the present case considered applying a sliding bearing to the rotating shaft of a motor (for example, a motor of an electric vehicle) that can rotate at a high rotational speed, and obtained the following findings in the process of developing this sliding bearing.

[0005] First, when the rotational speed of the rotating shaft is relatively low, the load capacity of the sliding bearing tends to be low. However, when the rotational speed of the rotating shaft is relatively high, the load capacity of the sliding bearing increases due to the wedge effect and throttling effect, while losses due to fluid resistance (friction loss) tend to increase. Therefore, it is desirable to ensure the load capacity of the sliding bearing in the low rotational speed range of the rotating shaft, and to suppress the load capacity of the sliding bearing and reduce friction loss in the high rotational speed range of the rotating shaft. Accordingly, the inventors of this invention considered using a high-viscosity fluid and a low-viscosity fluid, applying the high-viscosity fluid mainly to the sliding bearing in the low rotational speed range of the rotating shaft, and applying the low-viscosity fluid mainly to the sliding bearing in the high rotational speed range of the rotating shaft.

[0006] Furthermore, the inventors considered cooling the motor by supplying a predetermined fluid into the motor. In this case, it is desirable to apply a low-viscosity fluid (such as a refrigerant) to suppress resistance within the motor. Therefore, the inventors considered cooling the motor with the same low-viscosity fluid applied to the sliding bearing described above. This is because it simplifies the system configuration and control configuration. However, since the sliding bearing described above applies not only low-viscosity fluid but also high-viscosity fluid, when this high-viscosity fluid flows from the sliding bearing into the motor, the stirring resistance inside the motor (especially the motor rotor) increases.

[0007] On the other hand, generally, a sealing member (mechanical seal) is used to seal the gap between the rotating shaft and the housing in a motor. Such sealing members use a high-viscosity fluid (such as oil) to seal the gap. Therefore, the inventors of this invention thought it would be good to apply the same high-viscosity fluid used in the sliding bearing described above to the sealing member as well. However, since low-viscosity fluids are also used in this sliding bearing, it is desirable to prevent these low-viscosity fluids from flowing into the sealing member in order to protect it.

[0008] The present invention was made to solve the problems of the prior art described above, and aims to suppress the increase in stirring resistance within the motor and protect the sealing member in a motor system having a motor cooled by a low-viscosity fluid, a sliding bearing lubricated using a high-viscosity fluid and a low-viscosity fluid, and a sealing member utilizing a high-viscosity fluid. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a motor system comprising: a motor including a rotor and a stator, a rotating shaft connected to the rotor, and a housing that accommodates the rotor, stator, and rotating shaft; a sliding bearing that is lubricated by a fluid and supports the rotating shaft of the motor; a first passage and a second passage for supplying a first fluid and a second fluid having a lower viscosity than the first fluid, respectively, into the sliding bearing as fluids to lubricate the sliding bearing; a third passage for supplying the second fluid into the motor to cool the motor; and a sealing member to which the first fluid is supplied and which uses the first fluid to seal the gap between the portion of the rotating shaft extending from the housing of the motor to the outside and the housing, wherein the first passage is configured to supply the first fluid to a position in the sliding bearing that is on the sealing member side in the axial direction, and the second passage is configured to supply the second fluid to a position in the sliding bearing that is on the rotor side in the axial direction.

[0010] According to the present invention configured in this manner, the motor system supplies a high-viscosity first fluid from the first passage to the location on the seal member side of the sliding bearing, thereby suppressing the flow of a low-viscosity second fluid into the seal member and protecting the seal member. In addition, the motor system supplies a low-viscosity second fluid from the second passage to the location on the rotor side of the sliding bearing, thereby suppressing the flow of the high-viscosity first fluid into the motor and suppressing the increase in stirring resistance within the motor. Thus, according to the present invention, it is possible to suppress the increase in stirring resistance within the motor and protect the seal member.

[0011] In the present invention, preferably, the second passage and the third passage merge upstream of these passages. According to the present invention configured in this way, since the fluid that lubricates the sliding bearing and the fluid that cools the motor are of the same type (second fluid), the configuration of the motor system can be simplified.

[0012] In the present invention, preferably, the sliding bearing further includes a groove formed on the sliding surface of the sliding bearing, extending radially and circumferentially, configured to divide the sliding surface into a plurality of sections in the axial direction, and a discharge hole formed in the groove for discharging first and second fluids from the sliding bearing, wherein the first passage is configured to supply the first fluid to the section located on the sealing member side in the axial direction among the plurality of sections, and the second passage is configured to supply the second fluid to the section located on the rotor side in the axial direction among the plurality of sections. With the present invention configured in this way, multiple sections (hereinafter referred to as "divided sections") are formed by the grooves, and discharge holes are provided in these grooves. As a result, the fluid in each divided section flows out through the grooves defining each divided section and through the discharge holes, preventing the fluids from mixing in adjacent divided sections. Consequently, it is possible to reliably prevent the second fluid from flowing into a sealing member near a divided section where a first passage is provided (where the first fluid is supplied), and to reliably prevent the first fluid from flowing into a rotor near a divided section where a second passage is provided (where the second fluid is supplied). Therefore, the present invention makes it possible to effectively suppress the increase in stirring resistance within the motor and protect the sealing member.

[0013] In the present invention, preferably, the first passage is configured to supply a first fluid to a section located at the end on the sealing member side in the axial direction among a plurality of sections, and the second passage is configured to supply a second fluid to a section located at the end on the rotor side in the axial direction among a plurality of sections. With the present invention configured in this way, it is possible to more reliably prevent the second fluid from flowing into the sealing member, and also to more reliably prevent the first fluid from flowing into the rotor.

[0014] In the present invention, preferably, the motor system further comprises a fourth passage and a fifth passage for supplying a first fluid and a second fluid, respectively, to a predetermined section between a section provided with a first passage and a section provided with a second passage, a first valve and a second valve provided in the fourth passage and the fifth passage, and a control device configured to control the opening and closing of the first valve and the second valve, respectively, so as to switch the fluid supplied to the predetermined section between the first fluid and the second fluid. With the present invention configured in this way, the first fluid and the second fluid are supplied separately from the fourth passage and the fifth passage to a predetermined section among the multiple divided sections, so that the viscosity of the predetermined divided section can be appropriately changed. As a result, the average viscosity of the fluid in the sliding bearing can be changed, and the load of the sliding bearing can be controlled. In this invention, multiple divided sections are formed by grooves, and discharge holes are provided in these grooves to prevent the fluids from mixing in adjacent divided sections. Therefore, since the viscosity in each divided section does not fluctuate due to the mixing of the first fluid and the second fluid, the viscosity of each fluid in each divided section can be accurately adjusted, making it possible to achieve a desired average viscosity in the sliding bearing. Accordingly, with the present invention, the load of the sliding bearing can be accurately controlled, so that both the load capacity of the sliding bearing 15 and friction reduction can be achieved without complicating the control configuration.

[0015] In the present invention, preferably, the control device is configured to selectively perform, based on the rotational speed of the rotating shaft, a control that opens a first valve and closes a second valve to supply a first fluid to a predetermined section, and a control that closes a first valve and opens a second valve to supply a second fluid to a predetermined section. According to the present invention configured as described above, by switching the supply of the first and second fluids to a predetermined division section according to the rotational speed of the rotating shaft, it is possible to accurately achieve both ensuring the load capacity of the sliding bearing and reducing friction.

[0016] In a preferred example of the present invention, the first fluid is oil and the second fluid is CO2.

Advantages of the Invention

[0017] According to the present invention, in a motor system having a motor cooled by a low-viscosity fluid, a sliding bearing lubricated using a high-viscosity fluid and a low-viscosity fluid, and a seal member using a high-viscosity fluid, it is possible to suppress an increase in stirring resistance in the motor and protect the seal member.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic configuration diagram of a vehicle to which a motor system according to an embodiment of the present invention is applied. [Figure 2] It is a schematic configuration diagram of a refrigerant circulation system according to an embodiment of the present invention. [Figure 3] It is a schematic configuration diagram of a motor system according to an embodiment of the present invention. [Figure 4] Figures 4(a) and (b) are schematic configuration diagrams of a sliding bearing according to an embodiment of the present invention. [Figure 5] Figures 5(a) and (b) are explanatory diagrams of load loads realized by a sliding bearing according to an embodiment of the present invention. [Figure 6] It is a block diagram showing the electrical configuration of a motor system according to an embodiment of the present invention. [Figure 7] It is a time chart showing control according to an embodiment of the present invention. [Figure 8] It is a flowchart showing control according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0019] <0A motor system according to an embodiment of the present invention will be described below with reference to the attached drawings.

[0020] [Overall structure] First, referring to Figure 1, this is a schematic diagram of a vehicle to which the motor system according to this embodiment is applied.

[0021] As shown in Figure 1, the vehicle 300 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 mainly includes a motor 1 that generates power to drive the vehicle 300, a compressor 3 that compresses the refrigerant supplied to the motor 1, and a heat exchanger (condenser) 5 that includes a condenser and a fan, etc., for cooling the refrigerant compressed by the compressor 3.

[0022] The refrigerant circulation system 100 circulates a CO2 refrigerant (hereinafter sometimes simply referred to as "refrigerant") as a natural refrigerant. This CO2 refrigerant may contain not only CO2 but also refrigerant oils such as PAG and additives. Because such a CO2 refrigerant is used, the compressor 3 is configured to compress the refrigerant to a very high pressure. The motor 1 uses the refrigerant thus compressed by the compressor 3 (typically in a supercritical state) for lubrication of the sliding bearings supporting the rotating shaft and for cooling the rotor and stator. In this case, the motor 1 is configured to function as an evaporator in the refrigeration cycle. For example, in the refrigerant circulation system 100, high-temperature liquid refrigerant is supplied from the compressor 3 to the heat exchanger 5, low-temperature liquefied refrigerant is supplied from the heat exchanger 5 to the motor 1, and high-temperature gaseous refrigerant is supplied from the motor 1 to the compressor 3. The refrigerant compressed by the compressor 3 may also be used for air conditioning in an air conditioner or for cooling a battery.

[0023] [Refrigerant circulation system configuration] Next, with reference to Figure 2, the refrigerant circulation system 100 according to this embodiment will be described in detail. Figure 2 is a schematic diagram of the refrigerant circulation system 100 according to this embodiment.

[0024] As shown in Figure 2, the refrigerant circulation system 100 mainly includes, in addition to the motor 1, compressor 3, and heat exchanger 5 described above, a pair of sliding bearings 15 that support the rotating shaft 13 of the motor 1, an oil tank 6 for storing oil used for lubricating the sliding bearings 15, refrigerant passages 21-26 through which the refrigerant (CO2 refrigerant) flows, oil passages 27 and 28 through which the oil flows, and a mixed fluid passage 29 through which a mixed fluid of refrigerant and oil passes. For example, the oil is refrigerant oil such as PAG. The motor 1 and sliding bearings 15, etc., constitute the motor system 200 (details will be described later).

[0025] The refrigerant passage 21 is a passage for supplying refrigerant from the compressor 3 to the motor 1, etc., via the heat exchanger 5, and branches into refrigerant passage 22 and refrigerant passage 23 downstream of the heat exchanger 5. The refrigerant passage 21 is equipped with a refrigerant temperature sensor 51 for detecting the temperature of the refrigerant and a refrigerant pressure sensor 52 for detecting the pressure of the refrigerant.

[0026] Refrigerant passage 22 is a passage for supplying refrigerant into the sliding bearing 15, and refrigerant passage 23 is a passage for supplying refrigerant into the motor 1. These refrigerant passages 22 and 23 supply liquid (typically in a supercritical state) refrigerant supplied from the heat exchanger 5 via refrigerant passage 21 to the sliding bearing 15 and the motor 1, respectively. The refrigerant supplied to the sliding bearing 15 is used for lubrication of the sliding bearing 15, and the refrigerant supplied to the motor 1 is used for cooling the motor 1. In addition, a flow control valve 30 is provided in refrigerant passage 23 to adjust the flow rate of the refrigerant.

[0027] The refrigerant passage 24 is a passage for supplying the refrigerant discharged from the motor 1 to the compressor 3. A refrigerant passage 25 is connected to the refrigerant passage 24. One end of the refrigerant passage 25 is connected to the refrigerant passage 21 downstream of the heat exchanger 5, and the other end is connected to the refrigerant passage 24. It functions to return the refrigerant from the heat exchanger 5 to the compressor 3 without passing through the motor 1 or the sliding bearing 15. Check valves 41 and 42 are provided in the refrigerant passages 24 and 25, respectively.

[0028] The oil passage 27 is a passage for supplying oil stored in the oil tank 6 to the sliding bearing 15. The oil supplied to the sliding bearing 15 is used for lubrication of the sliding bearing 15 together with the refrigerant mentioned above. The oil passage 27 is equipped with an oil pump 38 for pumping the oil, an oil temperature sensor 54 for detecting the oil temperature, and an oil pressure sensor 55 for detecting the oil pressure. An oil passage 28 is also connected to the oil passage 27 for returning the oil in the passage 27 to the oil tank 6. A check valve 44 is provided in this oil passage 28.

[0029] The mixed fluid passage 29 is a passage for supplying the mixed fluid of refrigerant and oil discharged from the sliding bearing 15 to the oil tank 6. The oil tank 6 is configured to separate the oil from the mixed fluid supplied from this mixed fluid passage 29 (gas-liquid separation), store the separated oil, and supply the remaining refrigerant (which also contains a small amount of oil) from the refrigerant passage 26 to the refrigerant passage 24. A check valve 43 is provided in this refrigerant passage 26. The oil tank 6 is also equipped with an oil level sensor 53 for detecting the level of the stored oil.

[0030] [Motor System Configuration] Next, the configuration of the motor system 200 according to this embodiment will be specifically described with reference to Figures 3 to 5.

[0031] First, Figure 3 is a schematic diagram of the motor system 200 according to this embodiment. Specifically, Figure 3 is a cross-sectional view of the motor system 200 along the axial direction. Note that in Figure 3, the vertical positions of the refrigerant passage 22 and the oil passage 27 are shown in reverse compared to Figure 2 (the same applies to the figures described later).

[0032] As shown in Figure 3, the motor system 200 has a motor 1 which includes a rotor 11 and a stator 12, a rotating shaft 13 connected to the rotor 11 and one end of which is connected to the transaxle (not shown) of the vehicle 300, and a housing 14 which houses the rotor 11, stator 12, and rotating shaft 13, and also has a pair of sliding bearings 15 which support the rotating shaft 13 of the motor 1. This pair of sliding bearings 15 is also housed in the housing 14 of the motor 1.

[0033] As described above, in motor 1, refrigerant (liquefied refrigerant) is supplied to the rotor 11 and stator 12 from the refrigerant passage 23. The refrigerant supplied to motor 1 in this way is used to cool the rotor 11 and stator 12, in particular the coils (not shown) inside the stator 12. In this case, the refrigerant exchanges heat with the relatively high temperature of the stator 12, etc. (at this time the refrigerant evaporates in the coils of the stator 12), thus realizing the function of an evaporator in a refrigeration cycle. The refrigerant used for cooling in motor 1 is then discharged from the refrigerant passage 24.

[0034] Next, the pair of sliding bearings 15 are arranged symmetrically (left-right symmetrically) opposite each other with respect to the rotor 11 in the axial direction. Each of these sliding bearings 15 is supplied with oil from two oil passages 27 (27a, 27b) and refrigerant from two refrigerant passages 22 (22a, 22b). These refrigerant and oil are supplied to the gap between the inner circumferential surface of the sliding bearing 15 and the outer circumferential surface of the rotating shaft 13 of the motor 1, and are used to lubricate the sliding bearing 15 when it supports the rotating shaft 13. The refrigerant and oil used to lubricate the sliding bearings 15 are discharged together as a mixed fluid from the mixed fluid passage 29. In addition, the refrigerant used to lubricate the sliding bearings 15, especially the refrigerant used at the end of the sliding bearing 15 on the rotor 11 side, flows into the space in the housing 14 where the rotor 11 and stator 12 are housed, and is discharged together with the refrigerant used to cool the motor 1 from the refrigerant passage 24.

[0035] Specifically, the oil passages 27a and 27b supply oil to two different locations along the axial direction of the sliding bearing 15, and the refrigerant passages 22a and 22b supply refrigerant to two different locations along the axial direction of the sliding bearing 15. More specifically, the oil passage 27a is configured to supply oil to a location in the sliding bearing 15 that is on the opposite side of the rotor 11 in the axial direction (on the side of the seal member 18 for one of the pair of sliding bearings 15), and the refrigerant passage 22b is configured to supply refrigerant to a location in the sliding bearing 15 that is on the rotor 11 side in the axial direction. In contrast, the oil passage 27b and the refrigerant passage 22a are configured to supply oil and refrigerant, respectively, to locations in the axial direction between the respective supply locations of the oil passage 27a and the refrigerant passage 22a. In this case, the oil passage 27b and the refrigerant passage 22a supply oil and refrigerant, respectively, to almost the same locations in the axial direction; that is, the locations in the axial direction where the oil passage 27b supplies oil and where the refrigerant passage 22a supplies refrigerant are almost the same. On the other hand, no refrigerant is supplied to the locations where the oil passage 27a supplies oil in the axial direction, and no oil is supplied to the locations where the refrigerant passage 22b supplies refrigerant in the axial direction.

[0036] Furthermore, the motor system 200 has an oil bearing valve 31 provided in the oil passage 27b, which can switch between supplying and shutting off oil by opening and closing it, and a refrigerant bearing valve 32 provided in the refrigerant passage 22a, which can switch between supplying and shutting off refrigerant by opening and closing it.

[0037] Furthermore, the motor system 200 also includes a sealing member 18 for sealing the side of the rotating shaft 13 that is connected to the transaxle or the like (the side where the sliding bearing 15 shown on the left in Figure 3 is provided). This sealing member 18 is provided to prevent fluid leakage from the gap between the portion of the rotating shaft 13 that extends from the housing 14 to the outside and the housing 14. The sealing member 18 is configured as a mechanical seal that uses oil supplied from an oil passage 27d connected to the oil passage 27a to prevent fluid leakage.

[0038] Furthermore, oil corresponds to an example of the "first fluid" in this invention, and refrigerant (CO2 refrigerant) corresponds to an example of the "second fluid" in this invention. Also, oil passage 27a, refrigerant passage 22b, and refrigerant passage 23 correspond to the "first passage," "second passage," and "third passage," respectively, oil passage 27b and refrigerant passage 22a correspond to the "fourth passage" and "fifth passage," respectively, and oil bearing valve 31 and refrigerant bearing valve 32 correspond to the "first valve" and "second valve," respectively, in this invention.

[0039] Next, Figure 4 is a schematic diagram illustrating the sliding bearing 15 according to this embodiment in more detail. Specifically, Figure 4(a) is a perspective view of one of the pair of sliding bearings 15 (the sliding bearing 15 shown on the left in Figure 3, that is, the sliding bearing 15 on the side where the seal member 18 is provided), and Figure 4(b) is a cross-sectional view of this sliding bearing 15 viewed along the axial direction.

[0040] As shown in Figures 4(a) and (b), and especially in Figure 4(b), the sliding bearing 15 (as described above, one of a pair of sliding bearings 15; the same applies hereinafter) has two annular grooves 15a formed on its sliding surface (inner circumferential surface) that extend radially and around the entire circumference in the circumferential direction. The sliding surface of the sliding bearing 15 is divided into three sections (divided sections) R1 to R3 in the axial direction by these two grooves 15a. The divided sections R1 and R3 at both ends have approximately the same length along the axial direction, but the divided section R2, located in the middle between divided sections R1 and R3, has a longer length along the axial direction than divided sections R1 and R3.

[0041] Furthermore, the sliding bearing 15 has a discharge hole 15b formed in each of the two grooves 15a for discharging refrigerant and oil from the sliding bearing 15, supply holes 15c1 and 15c2 for supplying oil to the divided sections R1 and R2, respectively, and supply holes 15c3 and 15c4 for supplying refrigerant to the divided sections R2 and R3, respectively. The discharge hole 15b is in communication with the mixed fluid passage 29, the supply holes 15c1 and 15c2 are in communication with the oil passages 27a and 27b, respectively, and the supply holes 15c3 and 15c4 are in communication with the refrigerant passages 22a and 22b, respectively. In this case, the oil passage 27a is configured to supply oil to divided section R1, which is at the end of divided sections R1 to R3 on the sealing member 18 side in the axial direction, and the refrigerant passage 22b is configured to supply refrigerant to divided section R3, which is at the end of divided sections R1 to R3 on the rotor 11 side in the axial direction. Furthermore, two or more discharge holes 15b may be provided on the same groove 15a.

[0042] With this type of sliding bearing 15, two grooves 15a form three axially divided sections R1 to R3, and discharge holes 15b are provided in these grooves 15a. As a result, the fluid (oil or refrigerant) in each divided section R1 to R3 flows out through the grooves 15a that define each divided section R1 to R3 and out through the discharge holes 15b. This prevents the fluid from moving back and forth between adjacent divided sections R1 to R3 and mixing of the fluids in each divided section R1 to R3. This is because the size of the grooves 15a (e.g., on the order of millimeters) is much larger than the gap between the rotating shaft 13 of the motor 1 and the sliding bearing 15 (e.g., on the order of micrometers), so the fluid in each divided section R1 to R3 flows into the grooves 15a rather than passing through them to adjacent divided sections.

[0043] In particular, according to this embodiment, as described above, it is possible to prevent the oil and refrigerant from mixing in each of the divided sections R1 to R3, so that the refrigerant does not flow into the sealing member 18 adjacent to divided section R1 (where only oil is supplied), and the sealing member 18 can be protected. In addition, it is possible to prevent oil from flowing into the rotor 11 adjacent to divided section R3 (where only refrigerant is supplied), and an increase in stirring resistance inside the motor 1 can be suppressed.

[0044] In this configuration, only oil is supplied to section R1 via the oil passage 27a and supply hole 15c1, and only refrigerant is supplied to section R3 via the refrigerant passage 22b and supply hole 15c4. In contrast, in section R2, oil is supplied via the oil passage 27b and supply hole 15c2, and refrigerant is supplied via the refrigerant passage 22a and supply hole 15c3. As described above, the oil passage 27b and refrigerant passage 22a applied to section R2 are provided with an oil bearing valve 31 and a refrigerant bearing valve 32, respectively (Figure 3). In this embodiment, by opening one of the oil bearing valve 31 and the refrigerant bearing valve 32 and closing the other, only oil or refrigerant is supplied to section R2 (i.e., both oil and refrigerant are not supplied simultaneously), and by changing the open / closed state of the oil bearing valve 31 and the refrigerant bearing valve 32, the fluid supplied to section R2 is switched between oil and refrigerant.

[0045] Next, Figure 5 is an explanatory diagram of the load load realized by the sliding bearing 15 according to this embodiment. Specifically, the top of Figures 5(a) and (b) shows the supply state of oil or refrigerant in one of the pair of sliding bearings 15 (the sliding bearing 15 shown on the left in Figure 3, i.e., the sliding bearing 15 on the side where the seal member 18 is provided), and the bottom of Figures 5(a) and (b) shows the viscosity distribution of the fluid in the gap between the rotating shaft 13 of the motor 1 and the sliding bearing 15 and its average viscosity. In Figures 5(a) and (b), the viscosity of the fluid is represented by the intensity of the color (high viscosity oil is represented by a dark color, and low viscosity refrigerant is represented by a light color), and "↑" or "↓" indicates the supply of the corresponding fluid, and "×" indicates the cessation of the supply of the corresponding fluid.

[0046] Figure 5(a) shows the case where oil is supplied to divided sections R1 and R2 and refrigerant is supplied to divided section R3. In this case, oil is used as the fluid supplied to divided section R2 instead of refrigerant (the fluids supplied to divided sections R1 and R3 are fixed as oil and refrigerant, respectively). In this case, the oil bearing valve 31 of the oil passage 27b is opened, while the refrigerant bearing valve 32 of the refrigerant passage 22a is closed. In the case shown in Figure 5(a), the viscosity (oil viscosity) in divided sections R1 and R2 is higher than the viscosity (refrigerant viscosity) in divided section R3. In this case, the average viscosity of the viscosity distribution becomes relatively high (lower right of Figure 5(a)). As a result, the load on the sliding bearing 15 becomes relatively large.

[0047] Figure 5(b) shows the case where oil is supplied to section R1 and refrigerant is supplied to sections R2 and R3. In this case, refrigerant is used instead of oil as the fluid supplied to section R2. In this case, the oil bearing valve 31 of the oil passage 27b is closed, while the refrigerant bearing valve 32 of the refrigerant passage 22a is opened. In the case shown in Figure 5(b), the viscosity of section R2 and R3 (viscosity of the refrigerant) is lower than the viscosity of section R1 (viscosity of the oil). In this case, the average viscosity of the viscosity distribution (lower right of Figure 5(b)) is lower than the average viscosity in the case of Figure 5(a). As a result, the load on the sliding bearing 15 becomes relatively small.

[0048] In this embodiment, the load applied by the sliding bearing 15 can be switched by switching the fluid supplied to the divided section R2 between oil and refrigerant. This makes it possible to apply a relatively large load, as shown in Figure 5(a), in the low rotation range of the motor shaft 13, and a relatively small load, as shown in Figure 5(b), in the high rotation range of the motor shaft 13. In this embodiment, as described above, by forming divided sections R1 to R3 with the groove 15a, it is possible to prevent the fluids from mixing in adjacent divided sections R1 to R3. Therefore, when both oil and refrigerant are applied to the sliding bearing 15, the oil and refrigerant do not mix in adjacent divided sections R1 to R3, so that the viscosity of the fluid in each divided section R1 to R3 remains almost constant (in other words, the viscosity in each divided section R1 to R3 does not fluctuate due to the mixing of oil and refrigerant), and the desired average viscosity can be reliably achieved. As a result, according to this embodiment, it is possible to accurately control the load applied by the sliding bearing 15.

[0049] The average viscosity within the sliding bearing 15 varies depending on the length of the divided sections R1 to R3 along the axial direction. Therefore, it is best to set the length of each divided section R1 to R3 along the axial direction according to the desired average viscosity to be achieved.

[0050] [Electrical configuration] Next, the electrical configuration of the motor system 200 according to this embodiment will be described with reference to Figure 6. Figure 6 is a block diagram showing the electrical configuration of the motor system 200 according to this embodiment.

[0051] As shown in Figure 6, the motor system 200 has a control device 80 configured to perform various controls in the system. The control device 80 is composed of a computer comprising one or more processors 80a (typically a CPU) and memory 80b such as ROM or RAM for storing various programs (including basic control programs such as an OS and application programs launched on the OS to realize specific functions) and various data that are interpreted and executed on the processors 80a.

[0052] In addition to the sensors 51 to 55 described above (see Figure 2), the motor system 200 also includes a motor speed sensor 56 for detecting the motor speed of motor 1 (the rotational speed of the rotor 11 and rotating shaft 13, which is synonymous with rotational speed), a vehicle speed sensor 57 for detecting the speed of vehicle 300, an accelerator opening sensor 58 for detecting the accelerator opening corresponding to the amount the accelerator pedal is pressed in vehicle 300, and a brake sensor 59 for detecting the operation of the brake pedal in vehicle 300.

[0053] The control device 80 supplies control signals to the motor 1, compressor 3, flow control valve 30, oil bearing valve 31, refrigerant bearing valve 32, oil pump 38, and oil level warning light 39 based on the detection signals from these sensors 51 to 59. The oil level warning light 39 is a lamp that warns when the level of oil stored in the oil tank 6 (detected by the oil level sensor 53) is below a predetermined value.

[0054] In this embodiment, the control device 80 primarily controls the opening and closing of the oil bearing valve 31 and the refrigerant bearing valve 32, respectively, in order to switch the fluid supplied to the divided section R2 of the sliding bearing 15 between oil and refrigerant, based on the motor rotation speed detected by the motor rotation speed sensor 56. Specifically, the control device 80 selectively performs two actions based on the motor rotation speed: one that opens the oil bearing valve 31 and closes the refrigerant bearing valve 32 to supply oil to the divided section R2, and another that closes the oil bearing valve 31 and opens the refrigerant bearing valve 32 to supply refrigerant to the divided section R2.

[0055] [Control Method] Next, the control performed by the control device 80 of the motor system 200 in this embodiment will be specifically described. First, with reference to Figure 7, the flow of control performed by the control device 80 in this embodiment will be described. Figure 7 is a time chart showing the control according to this embodiment. Figure 7 shows, from top to bottom, the time changes of the motor rotation speed, the load by the sliding bearing 15 (corresponding to the viscosity of the fluid in the sliding bearing 15), the opening and closing of the refrigerant bearing valve 32, and the opening and closing of the oil bearing valve 31.

[0056] As shown in Figure 7, the motor speed increases at time t11. This reduces the load that the sliding bearing 15 must provide (hereinafter referred to as the "required load"), which is determined according to the motor speed. Therefore, at time t11, in order to reduce the load on the sliding bearing 15, the control device 80 controls the oil bearing valve 31 to close while opening the refrigerant bearing valve 32, thereby switching the fluid supplied to the divided section R2 of the sliding bearing 15 from oil to refrigerant.

[0057] Next, with reference to Figure 8, a flowchart illustrating the specific control according to this embodiment will be described. This flow is repeatedly executed by the control device 80 at predetermined intervals. Specifically, the processor 80a within the control device 80 reads a program stored in memory 80b and executes the program, thereby realizing the control related to this flow.

[0058] First, in step S10, the control device 80 acquires various information, such as the detected values, from the sensors 51 to 59 (Figure 6) described above. Then, the control device 80 proceeds to step S11 and determines whether the oil level detected by the oil level sensor 53 is above a predetermined value. If the control device 80 does not determine that the oil level is above a predetermined value (step S11: No), that is, if the oil level is below a predetermined value, it proceeds to step S12 and illuminates the oil level warning light 39.

[0059] In response, if the control device 80 determines in step S11 that the oil level is above a predetermined value (step S11: Yes), it proceeds to step S13. In step S13, the control device 80 determines whether motor 1 is stopped or not based on the motor rotation speed detected by the motor rotation speed sensor 56. If the control device 80 determines that motor 1 is stopped (step S13: Yes), it proceeds to step S14 and determines whether there is a motor start request or not based on the start switch of the vehicle 300 and the accelerator opening detected by the accelerator opening sensor 58. If the control device 80 determines that there is a motor start request (step S14: Yes), it proceeds to step S15, while if it does not determine that there is a motor start request (step S14: No), it terminates the control related to this flow.

[0060] In step S15, before starting the motor 1, the control device 80 opens the oil bearing valve 31 and closes the refrigerant bearing valve 32 to supply oil to the divided section R2 of the sliding bearing 15 in order to ensure the load on the sliding bearing 15. Then, the control device 80 proceeds to step S16 to start the motor 1, and after that, proceeds to step S17 to perform control to adjust the rotational speed of the compressor 3.

[0061] On the other hand, if the control device 80 does not determine in step S13 that the motor 1 is stopped (step S13: No), that is, if the motor 1 is already operating, it proceeds to step S18. In step S18, the control device 80 determines the target motor rotation speed based on the accelerator opening detected by the accelerator opening sensor 58, and determines whether or not this target motor rotation speed has changed. As a result, if the control device 80 determines that the target motor rotation speed has changed (step S18: Yes), it proceeds to step S19. On the other hand, if it does not determine that the target motor rotation speed has changed (step S18: No), it proceeds to step S17 as described above without performing the processes in steps S19 to S21.

[0062] In step S19, the control device 80 determines the required load on the sliding bearing 15 based on the motor rotation speed detected by the motor rotation speed sensor 56, and determines whether this required load has decreased. In this case, the required load tends to decrease as the motor rotation speed increases. If the control device 80 determines that the required load has decreased as a result of step 19 (step S19: Yes), it proceeds to step S20. In this case, since the motor rotation speed increases, the control device 80 closes the oil bearing valve 31 and opens the refrigerant bearing valve 32 to supply refrigerant to the divided section R2 of the sliding bearing 15 in order to reduce the load on the sliding bearing 15. Then, the control device 80 proceeds to step S17 as described above.

[0063] On the other hand, if the control device 80 does not determine in step S19 that the required load has decreased (step S19: No), that is, if the required load has increased, it proceeds to step S21. In this case, since the motor rotation speed will decrease, the control device 80 opens the oil bearing valve 31 and closes the refrigerant bearing valve 32 to supply oil to the divided section R2 of the sliding bearing 15 in order to ensure the load on the sliding bearing 15. Then, the control device 80 proceeds to step S17 as described above.

[0064] In step S19, the control device 80 determined whether the required load on the sliding bearing 15 had decreased. However, in other examples, instead of making this determination, it may determine whether the motor rotation speed is above a predetermined value.

[0065] [Mechanism of Action and Effects] Next, the operation and effects of the motor system 200 according to this embodiment will be described.

[0066] In this embodiment, the motor system 200 includes a motor 1 comprising a rotor 11 and a stator 12, a rotating shaft 13 connected to the rotor 11, and a housing 14 that accommodates the rotor 11, stator 12, and rotating shaft 13; a sliding bearing 15 that is lubricated by fluid and supports the rotating shaft 13 of the motor 1; an oil passage 27a and a refrigerant passage 22b for supplying oil and a refrigerant (CO2 refrigerant) into the sliding bearing 15, respectively, in order to lubricate the sliding bearing 15; a refrigerant passage 23 for supplying a refrigerant into the motor 1 in order to cool the motor 1; and a sealing member 18 to which oil is supplied and which uses the oil to seal the gap between the portion of the rotating shaft 13 extending from the housing 14 to the outside of the motor 1 and the housing 14. The oil passage 27a is configured to supply oil to a position in the sliding bearing 15 that is on the sealing member 18 side in the axial direction, and the refrigerant passage 22b is configured to supply refrigerant to a position in the sliding bearing 15 that is on the rotor 11 side in the axial direction.

[0067] According to this embodiment, since oil is supplied from the oil passage 27a to the location on the sealing member 18 side of the sliding bearing 15, it is possible to suppress the flow of refrigerant into the sealing member 18 and protect the sealing member 18. In addition, since refrigerant is supplied from the refrigerant passage 22b to the location on the rotor 11 side of the sliding bearing 15, it is possible to suppress the flow of oil into the motor 1 and suppress the increase in stirring resistance inside the motor 1. Thus, according to this embodiment, it is possible to suppress the increase in stirring resistance inside the motor 1 and protect the sealing member 18.

[0068] Furthermore, according to this embodiment, the refrigerant passage 22b and the refrigerant passage 23 merge upstream of these passages. As a result, the refrigerant that lubricates the sliding bearing 15 and the refrigerant that cools the motor 1 are of the same type (refrigerant), which simplifies the configuration of the motor system 200.

[0069] Furthermore, according to this embodiment, the sliding bearing 15 has two grooves 15a formed on its sliding surface that extend radially and circumferentially, and these grooves 15a divide the sliding surface of the sliding bearing 15 into a plurality of divided sections R1 to R3 in the axial direction. The sliding bearing 15 also has a discharge hole 15b formed in the grooves 15a for discharging oil and refrigerant from the sliding bearing 15. The oil passage 27a is configured to supply oil to divided section R1, which is located on the seal member 18 side in the axial direction among the divided sections R1 to R3 (specifically, located at the end on the seal member 18 side), and the refrigerant passage 22b is configured to supply refrigerant to divided section R3, which is located on the rotor 11 side in the axial direction among the divided sections R1 to R3 (specifically, located at the end on the rotor 11 side).

[0070] According to this embodiment, the groove 15a forms divided sections R1 to R3, and a discharge hole 15b is provided in the groove 15a. As a result, the fluid in each divided section R1 to R3 flows out from the discharge hole 15b via the groove 15a that defines each divided section R1 to R3, thus preventing the fluids from mixing in adjacent divided sections R1 to R3. Consequently, it is possible to reliably prevent refrigerant from flowing into the seal member 18 adjacent to divided section R1 (where only oil is supplied), and to reliably prevent oil from flowing into the rotor 11 adjacent to divided section R3 (where only refrigerant is supplied). Therefore, according to this embodiment, it is possible to more effectively suppress the increase in stirring resistance in the motor 1 and protect the seal member 18.

[0071] Furthermore, according to this embodiment, the motor system 200 further comprises an oil passage 27b and a refrigerant passage 22a for supplying oil and refrigerant to a divided section R2 located between divided section R1, which is provided with an oil passage 27a, and divided section R3, which is provided with a refrigerant passage 22b, among the divided sections R1 to R3; an oil bearing valve 31 and a refrigerant bearing valve 32 provided in the oil passage 27b and the refrigerant passage 22a, respectively; and a control device 80 configured to control the opening and closing of the oil bearing valve 31 and the refrigerant bearing valve 32, respectively, so as to switch between oil and refrigerant as the fluid supplied to the divided section R2.

[0072] In this embodiment, oil and refrigerant are supplied separately from the oil passage 27b and the refrigerant passage 22a to section R2 of section R1 to R3, so that the viscosity of section R2 can be appropriately changed. As a result, the average viscosity of the fluid in the sliding bearing 15 can be changed, and the load on the sliding bearing 15 can be controlled. In this embodiment, section R1 to R3 is formed by a groove 15a, and a discharge hole 15b is provided in this groove 15a to prevent the fluids from mixing in adjacent section R1 to R3. Therefore, since the viscosity in each section R1 to R3 does not fluctuate due to mixing of oil and refrigerant, the viscosity of each fluid in each section R1 to R3 can be accurately adjusted, making it possible to achieve a desired average viscosity in the sliding bearing 15. Accordingly, in this embodiment, the load on the sliding bearing 15 can be accurately controlled, so that both the load capacity of the sliding bearing 15 and friction reduction can be achieved without complicating the control configuration.

[0073] Furthermore, according to this embodiment, the control device 80 selectively performs two types of control based on the motor rotation speed (including the required load set based on the motor rotation speed): one that opens the oil bearing valve 31 and closes the refrigerant bearing valve 32 to supply oil to the divided section R2, and another that closes the oil bearing valve 31 and opens the refrigerant bearing valve 32 to supply refrigerant to the divided section R2. This ensures that the load capacity of the sliding bearing 15 is secured in the low rotation range, while reducing friction (reducing lubrication resistance) of the sliding bearing 15 in the high rotation range.

[0074] [Differentiation] In the embodiment described above, when the motor rotation speed became relatively high, the control device 80 stopped supplying oil to the divided section R2 and supplied refrigerant to the divided section R2 in order to reduce friction caused by oil in the sliding bearing 15 (reduction of lubrication resistance) (Figures 7 and 8). However, even if refrigerant is supplied to the divided section R2 in this way, it can be said that the effect of the refrigerant on the load capacity is almost negligible (because the load capacity of the refrigerant is low). In this case, it is considered that the oil and refrigerant supplied to the divided sections R1 and R3, especially the oil, can sufficiently secure the load capacity. On the other hand, preparing refrigerant to supply to the divided section R2 results in wasted energy consumption. For the reasons above, it can be said that it is not necessary to supply refrigerant to the divided section R2 when the motor rotation speed is relatively high.

[0075] Therefore, in the modified example, after stopping the supply of oil to the divided section R2, the supply of refrigerant to the divided section R2 is also stopped. In this case, after stopping the supply of oil to the divided section R2, oil remains in the divided section R2, which causes drag resistance. Therefore, in the modified example, after stopping the supply of oil to the divided section R2, the control device 80 supplies refrigerant to the divided section R2 for a predetermined time to wash away the oil remaining in the divided section R2 with the refrigerant (i.e., wash the oil-lubricated surface). Then, in the modified example, after supplying refrigerant to the divided section R2 for a predetermined time, the control device 80 stops the supply of refrigerant to the divided section R2.

[0076] According to this modified configuration, after stopping the supply of oil to the divided section R2 of the sliding bearing 15, refrigerant is supplied to the divided section R2 to wash away the oil remaining in the divided section R2 with the refrigerant (i.e., wash the oil-lubricated surface), thereby suppressing resistance due to oil drag. Furthermore, according to this modified configuration, after washing away the oil remaining in the divided section R2 with the refrigerant, the supply of refrigerant to the divided section R2 is stopped, thus suppressing the wasted energy consumption of preparing refrigerant for the divided section R2.

[0077] Furthermore, in the embodiment described above, the sliding bearing 15 had three divided sections R1 to R3 formed by two grooves 15a, but in a modified example, one groove 15a may form two divided sections, or three or more grooves 15a may form four or more divided sections.

[0078] Furthermore, in the above-described embodiment, oil and CO2 (CO2 refrigerant) were used as fluids with different viscosities (first and second fluids), but various fluids other than oil and CO2 may be used. [Explanation of symbols]

[0079] 1 motor 3 Compressors 5 Heat exchanger 6 Oil tank 11 rotors 12 staters 13 Rotation axis 15 Plain bearings 15a Groove 15b Discharge hole 15c1~15c4 Supply hole 21-26 Refrigerant passage 27, 28 Oil passages 29 Mixed fluid passage 80 Control device 100 Refrigerant Circulation System 200 Motor System 300 vehicles R1~R3 ​​Divided Section

Claims

1. A motor system, A motor comprising a rotor and a stator, a rotating shaft connected to the rotor, and a housing that accommodates the rotor, the stator, and the rotating shaft, A sliding bearing that provides lubrication with a fluid and supports the rotating shaft of the motor, To lubricate the sliding bearing, a first passage and a second passage are provided for supplying a first fluid and a second fluid having a lower viscosity than the first fluid, respectively, into the sliding bearing. A third passage for supplying the second fluid into the motor in order to cool the motor, A sealing member is provided to supply the first fluid and use the first fluid to seal the gap between the portion of the rotating shaft of the motor that extends from the housing to the outside and the housing, It has, The first passage is configured to supply the first fluid to a position in the sliding bearing that is on the sealing member side in the axial direction. The second passage is configured to supply the second fluid to a position in the sliding bearing that is on the rotor side in the axial direction. A motor system characterized by the following features.

2. The motor system according to claim 1, wherein the second passage and the third passage merge upstream of these passages.

3. The aforementioned sliding bearing is A groove formed on the sliding surface of the sliding bearing, extending radially and circumferentially, wherein the groove is configured to divide the sliding surface into a plurality of sections in the axial direction, The groove portion is formed with a discharge hole for discharging the first and second fluids from the sliding bearing, It further possesses, The first passage is configured to supply the first fluid to the section located on the sealing member side in the axial direction among the plurality of sections. The second passage is configured to supply the second fluid to the section of the plurality of sections located on the rotor side in the axial direction. The motor system according to claim 1.

4. The first passage is configured to supply the first fluid to the section located at the end of the plurality of sections on the sealing member side in the axial direction, The second passage is configured to supply the second fluid to the section located at the end of the plurality of sections on the rotor side in the axial direction. The motor system according to claim 3.

5. The motor system is at the end Among the plurality of sections, a fourth passage and a fifth passage are provided for supplying the first fluid and the second fluid, respectively, to a predetermined section between the section where the first passage is provided and the section where the second passage is provided. The first valve and the second valve are provided in the fourth passage and the fifth passage, respectively. A control device configured to control the opening and closing of the first valve and the second valve, respectively, so as to switch the fluid supplied to the predetermined section between the first fluid and the second fluid, The motor system according to claim 3, further comprising:

6. The motor system according to claim 5, wherein the control device is configured to selectively perform, based on the rotational speed of the rotating shaft, control to open the first valve and close the second valve in order to supply the first fluid to the predetermined section, and control to close the first valve and open the second valve in order to supply the second fluid to the predetermined section.

7. The first fluid is oil, and the second fluid is CO 2 The motor system according to any one of claims 1 to 6.

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