Rotating electrical machine and electrical vehicle

Abstract

A rotating electrical machine (100) comprises: a housing (3); a stator (10) that has a stator core (11) fixed to the housing (3) and a coil (12) wound around the stator core (11); and a rotor (20) that is rotatably supported on the housing (3) and has a rotor core (21) and a shaft (22). At least one of the rotor (20) and the housing (3) has a cooling liquid flow passage (20P, 31P) through which a cooling liquid (C) is supplied to a coil end (12E) of the coil. The hole diameter of an injection hole (21H, 31H) through which the cooling liquid (C) is injected from the cooling liquid flow passage (20P, 31P) into a space in the housing is smaller than the diameter of the cooling liquid flow passage (20P, 31P).

Description

Rotating electric machines and electric vehicles

[0001] The present disclosure relates to a rotating electric machine and an electric vehicle.

[0002] Conventionally, in rotating electrical machines such as motors and generators, a cooling method has been proposed in which a coolant is brought into contact with the stator core or the coil end portions of the stator in order to cool the coils wound around the stator core (see, for example, Patent Document 1). Patent Document 1 discloses a technology in which cooling oil is discharged from a housing toward the stator core and coil ends to cool the coil ends, and furthermore, the cooling oil comes into contact with the rotating rotor and splashes, and adheres to the coil ends, thereby providing an additional cooling effect.

[0003] Special Publication No. 2023-518387

[0004] Patent Document 1 proposes a method for improving the cooling of the coil ends by using oil that splashes from the rotating rotor toward the coil ends located outside it, in addition to the cooling oil that is poured directly onto the coil ends as described above. However, Patent Document 1 has a problem in that under low rotation speed and high torque driving conditions that cause the coils of a rotating electric machine to become hot, the cooling liquid that comes into contact with the rotor flows down due to gravity without splashing, making it impossible to provide a uniform additional cooling effect to the coil ends.

[0005] Furthermore, the method of directly pouring cooling oil onto the coil ends has limited flexibility in placement because the outlet must be adjusted to face the coil ends.Furthermore, changes in the drive conditions can cause changes in the viscosity and flow rate of the cooling oil or the airflow generated by rotor rotation, which can cause the trajectory of the discharged cooling liquid to deviate from the coil ends, reducing cooling efficiency.

[0006] The present disclosure aims to disclose technology for solving the above-mentioned problems, and to provide a rotating electric machine that can efficiently and uniformly cool coil ends and has a high degree of freedom in arranging cooling paths, and an electric vehicle equipped with such a rotating electric machine.

[0007] A rotating electric machine according to the present disclosure includes a housing, a stator having a stator core fixed to the housing and a coil wound around the stator core, and a rotor rotatably supported by the housing and having a rotor core and a shaft, wherein at least one of the rotor or the housing has a coolant flow path that supplies coolant to a coil end of the coil, and an injection hole that injects the coolant from the coolant flow path into a space within the housing has a hole diameter smaller than a diameter of the coolant flow path.An electric vehicle according to the present disclosure also includes a refrigerant circulation system that uses at least a portion of the coolant of the rotating electric machine as a refrigerant.

[0008] According to the rotating electric machine and electric vehicle according to the present disclosure, it is possible to provide a rotating electric machine that can efficiently and uniformly cool coil ends and has a high degree of freedom in arranging cooling paths, and an electric vehicle equipped with the rotating electric machine.

[0009] 10 is a cross-sectional view of a rotating electric machine according to a first embodiment, taken along a plane including the central axis of the shaft, illustrating a coolant flow path of the rotating electric machine. FIG. 11 is a cross-sectional view of an injection hole according to the first embodiment. FIG. 12 is a cross-sectional view of a cylindrical housing portion according to the first embodiment, taken perpendicular to the axial direction, illustrating a portion where an injection hole is present. FIG. 13 is a cross-sectional view of a rotating electric machine illustrating an example of providing an intra-housing flow path in a housing end plate according to the first embodiment. FIG. 14 is a cross-sectional view of a rotor according to the first embodiment, taken along a plane including the axis of the shaft. FIG. 15 is a cross-sectional view illustrating a modified example of a coolant flow path according to the first embodiment. FIG. 16 is a cross-sectional view of an injection hole according to the second embodiment. FIG. 17 is a cross-sectional view of a modified example of an injection hole according to the second embodiment. FIG. 18 is a cross-sectional view of a modified example of a injection hole according to the second embodiment. FIG. 19 is a cross-sectional view of a rotating electric machine according to a third embodiment, taken along a plane including the central axis of the shaft. FIG. 19 is a cross-sectional view taken along D-D of FIG. 10, illustrating a cross section of only the cylindrical housing portion and the coil end. FIG. 19 is a cross-sectional view illustrating a modified example of a cylindrical housing portion according to the third embodiment. FIG. 20 is a cross-sectional view illustrating a modified example of a cylindrical housing portion and a protrusion according to the third embodiment, partially cross-sectional view perpendicular to the axial direction. FIG. 21 is a plan view of an end plate of a rotor according to a fourth embodiment, viewed from the outside in the axial direction. Fig. 16 is a cross-sectional view perpendicular to the axial direction of a rotor core and permanent magnets according to embodiment 4. Fig. 17 is a cross-sectional view of a main part of a hollow flow path portion of a shaft and an end plate according to embodiment 4. Fig. 18 is a cross-sectional view taken along the line E-E in Fig. 16. Fig. 19 is a block diagram showing an example of a cooling circuit for an electric vehicle according to embodiment 5. Fig. 20 is a block diagram showing another example of a cooling circuit for an electric vehicle according to embodiment 5.

[0010] Embodiment 1. A rotating electric machine according to embodiment 1 will be described below with reference to the drawings. In this specification, unless otherwise specified, the terms "axial direction," "circumferential direction," "radial direction," "inner peripheral side," "outer peripheral side," "inner peripheral surface," and "outer peripheral surface" refer to the "axial direction," "circumferential direction," "radial direction," "inner peripheral side," "outer peripheral side," "inner peripheral surface," and "outer peripheral surface" of the rotor, respectively. Furthermore, unless otherwise specified, when "upper" or "lower" is mentioned, a plane perpendicular to the axial direction is assumed at the referenced location, and the side of that plane that includes the center point of the stator as the boundary is referred to as "lower," and the opposite side is referred to as "upper."

[0011] Fig. 1 is a cross-sectional view of a rotating electric machine 100 cut along a plane including the central axis O of a shaft 22, and shows a coolant flow path for a coolant C in the rotating electric machine 100. As shown in Fig. 1, the rotating electric machine 100 includes a housing 3, a stator 10, and a rotor 20. The housing 3 includes an annular housing cylindrical portion 31 and two housing end plates 32 that close openings on both sides of the housing cylindrical portion 31 in the axial direction Z. The stator 10 is fixed inside the housing cylindrical portion 31. The stator 10 includes a stator core 11 made of laminated electromagnetic steel plates and a coil 12 wound around the stator core 11.

[0012] A rotor 20 is disposed inside the stator 10. The rotor 20 is composed of a rotor core 21 made of laminated electromagnetic steel plates, permanent magnets (not shown) housed in a plurality of permanent magnet insertion holes in the rotor core 21, and a shaft 22 that transmits rotational power. The rotor 20 is rotatably supported with its outer peripheral surface facing the inner peripheral surface of the stator 10 via bearings 5 ​​fitted in the centers of the two housing end plates 32 described above.

[0013] In the example described in Figure 1, an inner rotor type is used in which the rotor 20 is arranged inside the stator 10, but the motor may also be an outer rotor type in which the rotor is arranged outside the stator, an axial gap type in which the stator and rotor are arranged opposite each other in the axial direction, or another arrangement.

[0014] The cooling performance of a motor, which is a type of rotating electrical machine, significantly affects its continuous operation performance and durability. For example, if the coil becomes hot due to copper loss during continuous operation, there is a concern that the coil may deteriorate. In particular, the coil ends exposed on the axial upper side of the stator core cannot dissipate heat to the stator core, so it is preferable to bring them into contact with a coolant to efficiently dissipate heat.

[0015] Therefore, the housing cylindrical portion 31 of the rotating electric machine 100 is provided with an in-housing flow path 31P (coolant flow path), and the coolant C is diffused from a plurality of injection holes 31H in the in-housing flow path 31P into the interior of the rotating electric machine 100 over a wider area than the diameter of the injection holes 31H. Specific details will be described later, but the in-housing flow path 31P is provided with a characteristic configuration, for example, at or upstream of the injection holes 31H, that serves as a means for diffusing the coolant C over a wider area than the diameter of the injection holes 31H. As a result, the coolant C floats at a high density in the space R within the housing where the coil ends 12E are exposed, and the coolant C adheres evenly to the surfaces of the coil ends 12E, enabling uniform cooling of the coil ends 12E.

[0016] Similarly, continuous operation of the rotating electric machine 100 at high temperatures may cause irreversible demagnetization of the permanent magnets, resulting in a decrease in maximum torque. Therefore, as shown in FIG. 1 , a rotor 20 is also provided with a rotor coolant flow path 20P. The rotor coolant flow path 20P consists of an intra-shaft flow path 22P formed hollow within the shaft 22 and an intra-rotor core flow path 21P formed within the rotor core 21. End plates may be provided on both sides of the rotor core 21 in the axial direction Z, and part of the rotor coolant flow path 20P may be formed within the end plates themselves or between the end plates and the laminated steel sheets of the rotor core 21. When the coolant C used to cool the permanent magnets is sprayed from the spray holes 21H at the ends of the rotor core 21 in the axial direction Z into the space R within the housing 3, the coolant C is dispersed wider than the diameter of the spray holes 21H, similar to the spray holes 31H in the housing cylindrical portion 31. This further increases the proportion of the coolant C floating in the space R within the housing 3, improving the cooling effect of the coil ends 12E.

[0017] Conventionally, a centrifugal spray method using the rotational force of the rotor has been proposed as a method for spraying coolant from the rotor toward the coil ends. However, a problem with this method is that under low rotation speed and high torque driving conditions where the coil generates a lot of heat, the coolant does not spray but flows down due to gravity, making it impossible to use for cooling the coil ends. In the first embodiment, the coolant C sprayed from the rotor 20 can be made to float in the space R in the form of fine droplets regardless of the rotation speed, so that the coolant C can be supplied to the coil ends 12E located vertically above and vertically to the side of the rotor 20.

[0018] As a secondary effect, the proportion of the coolant C floating in the space R within the housing 3 increases, which allows the coolant C to adhere to and wet the bearings 5 ​​located in the same space R. As a result, if the coolant C has properties as a lubricant for the bearings 5 ​​and electrical insulation properties, it can function as an insulating coating that suppresses electrical corrosion of the bearings 5.

[0019] The distribution of the amount of coolant C supplied to the stator 10 and the amount of coolant C supplied to the rotor 20 can be adjusted by changing the pressure loss by creating a difference in the inner diameter of the housing inner flow path 31P and the rotor coolant flow path 20P.

[0020] 2 is a cross-sectional view of the injection holes 31H and 21H. The diameters of the injection holes 31H and 21H provided at the outlets of the in-housing flow path 31P and the in-rotor-core flow path 21P are smaller than the diameters of the in-housing flow path 31P and the in-rotor-core flow path 21P. That is, the injection holes 31H and 21H have a tapered structure in which the diameter gradually decreases toward the outlet. As a result, the pressure of the injected coolant C decreases compared to before injection, but the flow rate increases. Furthermore, because the surrounding air is vigorously drawn into the discharged coolant C, the coolant C spreads over an area wider than the diameter of the injection holes 31H and 21H, allowing the coolant C to float in the space R within the housing 3 shown in FIG. 1.

[0021] Furthermore, by increasing the degree to which the cross-sectional area of ​​the tapered structure is reduced, or by increasing the supply flow rate and supply pressure of the coolant C per cross-sectional area of ​​the outlet, it is possible to make the droplets of coolant C sprayed from the spray holes 31H, 21H finer. By adjusting the spray so that the fine droplets are dispersed in a mist, it is possible to cause the coolant C to float at a high density in the space R within the housing 3 described above. Furthermore, by ensuring that the coolant C is evenly applied to the surface of the coil end 12E, it is possible to more uniformly cool the coil end 12E.

[0022] 3 is a cross-sectional view of the housing cylindrical portion 31 taken perpendicular to the axial direction Z, showing a portion where the injection holes 31H are present. The housing cylindrical portion 31 has an annular in-housing flow path 31P extending around the entire circumference inside the housing cylindrical portion 31. The in-housing flow path 31P opens in the radial direction X toward the space R within the housing 3 and has a plurality of injection holes 31H spaced apart in the circumferential direction Y. By giving the injection holes 31H the tapered structure shown in FIG. 2 , the pressure loss at the outlet increases, and the flow rate of the coolant C injected per unit time from one injection hole 31H becomes smaller than the flow rate when the coolant is sprayed from the housing to the coil end.

[0023] Therefore, in order to obtain the necessary cooling effect for the coil ends 12E, multiple injection holes 31H are arranged to supply a sufficient amount of coolant C. Note that, although the injection holes 31H are evenly arranged in the circumferential direction Y in Figure 3, they may be arranged unevenly as long as the amount of coolant C supplied is sufficiently large. In addition, because the coolant C after injection floats within the space R, it is not necessary to arrange the injection holes 31H specifically to target the coil ends 12E. As a result, there is a high degree of freedom in the arrangement of the in-housing flow passages 31P and the injection holes 31H, which reduces processing costs and enables the motor 100 to be made smaller by saving space for the in-housing flow passages 31P.

[0024] 4 is a cross-sectional view of a rotating electrical machine showing an example in which an in-housing flow passage 32P is provided in a housing end plate 32. The in-housing flow passage 32P and the injection holes 32H may be provided in only one housing end plate 32 of the housing 3, and the in-housing flow passage 32P may be designed to be short and simple.

[0025] 5 is a cross-sectional view of the rotor 20 according to the first embodiment, taken along a plane including the central axis O of the shaft 22. The rotor coolant flow path 20P is made up of an in-shaft flow path 22P that extends in the axial direction Z from one end of the shaft 22 and further extends in the radial direction X to open to the outside, a plurality of in-end plate flow paths 23P that are connected to the in-shaft flow path 22P and extend outward in the radial direction X through an end plate 23 provided at one end of the rotor core 21 in the axial direction Z, and a plurality of in-rotor core flow paths 21P that are connected to each in-end plate flow path 23P and extend in the axial direction Z inside the rotor core 21 along the permanent magnets M.

[0026] The outer end of the intra-end plate flow path 23P is connected to an injection hole 21H1 that opens through the end plate 23 in the axial direction Z, and the other end in the axial direction Z of the intra-rotor core flow path 21P is connected to an injection hole 21H2 that opens through the end plate 24. The coolant C that flows in from the intra-shaft flow path 22P is divided into a flow path that is injected from the injection hole 21H1 of one end plate 23 into the space R in the housing 3, and a flow path that flows along the side surface of the permanent magnet M in the axial direction Z and then is injected from the injection hole 21H2 provided in the opposite end plate 24 into the space R in the housing 3.

[0027] It should be noted that most of the flow rate of the cooling liquid C branched within the rotor 20 can be allocated to the permanent magnet M side, and if the right coil end 12E shown in Figure 1 is not sufficiently cooled, the shortage in the supply of cooling liquid C can be compensated for by adjusting the arrangement of the injection holes 32H of the housing end plate 32 shown in Figure 4. This makes it possible to supply the amount of cooling liquid C necessary to suppress irreversible demagnetization of the permanent magnets M due to heat.

[0028] Furthermore, similar to the housing 3, the injection holes 21H1, 21H2 provided in the end plates 23, 24 have a tapered structure as shown in Figure 2, so that the coolant C can be injected in the form of fine droplets into the space R within the housing 3 even under driving conditions where the rotor 20 is not rotating.

[0029] 6 is a cross-sectional view showing a modified example of a rotor coolant flow path 20P. As shown in Fig. 6, in an end-plate-less rotor 20, the in-shaft flow path 22P may be extended to the center of the rotor core 21 in the axial direction Z, and the in-rotor-core flow path 21P may be provided outward in the radial direction X to connect to the in-shaft flow path 22P and branch off to both sides in the axial direction Z along the permanent magnets M inside the permanent magnets M. In this case, for example, the hole diameter of the in-rotor-core flow path 21P may be reduced in the laminated steel plates at both ends in the axial direction Z to form injection holes 21H, thereby increasing the flow velocity of the coolant C after injection.

[0030] Furthermore, in order to widely diffuse the coolant C from the two injection holes 21H, it is preferable that the pressure of the coolant C flowing through the rotor coolant flow path 20P be kept high and the flow rate be kept high. For this reason, it is conceivable that the rotor core 21 shown in Figures 5 and 6 can improve the airtightness of the coolant flow path by filling the gaps (between the laminated magnetic steel sheets) with a resin such as an adhesive. Furthermore, when flow paths are provided in the end plates 23, 24, it is also advisable to fill the gaps between the end plates 23, 24 and the laminated steel sheets with resin.

[0031] In the first embodiment, a fluid having electrical insulation and anti-rust properties (such as ATF (Automatic Transmission Fluid)) is used as the coolant C. Note that if insulation around the coil 12 is ensured, a non-insulating fluid such as water can also be used, and a gas-liquid multiphase refrigerant such as that used in air conditioners may also be used. If water or a refrigerant is used as the coolant C, when the coolant C comes into contact with the coil end 12E, heat is removed from the coil end 12E by the latent heat of vaporization due to the phase change from a liquid state to a gas state, which is expected to improve cooling efficiency.

[0032] Furthermore, when the coolant C comes into contact with the heat-generating coil 12 and evaporates, the coolant C is prevented from accumulating in the gap G shown in Figure 4 between the stator core 11 and the rotor core 21, which is expected to reduce drag torque.

[0033] According to a first embodiment of the rotating electric machine, the rotating electric machine includes a housing, a stator having a stator core fixed to the housing and a coil wound around the stator core, and a rotor rotatably supported by the housing, the rotor having a rotor core and a shaft, wherein at least one of the rotor and the housing has a coolant flow path that supplies coolant to the coil ends of the coil, and the diameter of the injection holes that inject the coolant from the coolant flow path into the space within the housing is smaller than the diameter of the coolant flow path, so that the injected coolant is in the form of a mist that floats even under gravity, allowing the coolant to be sprayed in all directions even at low rotor rotation speeds and enabling uniform cooling of the coil ends. Furthermore, because the injection holes have a tapered shape, the small diameter near the outlet of the coolant flow path increases the flow rate of the injected coolant and forcefully draws in surrounding air, allowing the coolant to be dispersed over a wider area than the diameter of the injection holes. Furthermore, the rotor core of the rotor has an internal flow path through which the coolant flows along the permanent magnets housed in the rotor core, so that the coolant that dissipates heat generated in the permanent magnets can be reused to cool the coils. Furthermore, the rotor core is made of multiple laminated steel plates or multiple laminated steel plates and end plates, and the spaces between the laminated steel plates and between the laminated steel plates and the end plates are filled with resin, so that the coolant flow path within the rotor can be sealed and a high flow rate and high pressure of the coolant can be maintained all the way to the injection holes.

[0034] Embodiment 2. A rotating electric machine according to embodiment 2 will be described below, focusing on the differences from embodiment 1. In this embodiment, an injection hole structure that improves cooling effect and productivity will be described as an alternative to the configuration in which the coolant C is diffused wider than the diameter of the coolant flow path described in embodiment 1.

[0035] 7 is a cross-sectional view of the injection holes 231H, 221H. The in-housing flow path 31P and the in-rotor-core flow path 21P have an orifice OF, an intake port IN, and a mixing chamber RM located upstream of the injection holes 231H, 221H. The orifice OF is located upstream of the injection holes 231H, 221H and has an inner diameter smaller than those of the in-housing flow path 31P and the in-rotor-core flow path 21P (coolant flow path). The coolant C passes through the orifice OF, which is located upstream of the injection holes 231H, 221H and has a smaller inner diameter than those of the in-housing flow path 31P and the in-rotor-core flow path 21P (coolant flow path), and the flow velocity and pressure of the coolant C are increased. Taking advantage of this, the hole diameter of the orifice OF is set so that the pressure in the mixing chamber RM is lower than the air pressure of the gas inside the housing 3 (atmospheric pressure).

[0036] As a result, the momentum of the cooling liquid C passing through the orifice OF and the momentum of the air taken in from the intake port IN cause the cooling liquid C to break down into fine droplets in the mixing chamber RM. As a result, compared to the injection holes 31H and 21H in Figure 2, which mix the cooling liquid C with air after injection, the injection holes 231H and 221H shown in Figure 7 make it easier for the cooling liquid C to spread wider than the hole diameter of the injection holes 231H and 221H. Therefore, the droplets can be dispersed as an even finer mist.

[0037] 8 is a cross-sectional view of an injection hole 221H2 according to a modification of the second embodiment. A swirl chamber RM2 is provided in front of the injection hole 221H2 in the rotor core flow path 21P (as well as in the other coolant flow paths). Inside the swirl chamber RM2, the coolant C flows in a spiral pattern along the inner wall of the swirl chamber RM2, and is thereby widely dispersed throughout the space R within the housing 3 so as to spread from the injection hole 221H2.

[0038] 9 is a cross-sectional view of a nozzle part PA having an injection hole 221H3 according to a modification of Embodiment 2. The tip of the coolant flow path is divided into the nozzle part PA, which has each injection hole shown in FIGS. 2, 7, and 8 and a threaded portion S2 for connecting to a threaded portion S1 provided on the rotor core 21 or the housing end plate 32. This makes it easy to mold the nozzle part PA by die-cutting, which is expected to improve mass productivity.

[0039] 9 may be a nozzle of a spray device (sprayer). The nozzle part may have any shape as long as it has the function of spraying the coolant C in a mist, and may be configured to include various types of sprayers (spray nozzle type, electrostatic nozzle type, ultrasonic spray type, etc.) having a spray function at the tip of the coolant flow path.

[0040] The tapered structures shown in FIG. 2 described in the first embodiment and in FIGS. 7 to 9 of the second embodiment are linearly tapered, but may be curvedly tapered or may have a stepped structure in which different hole diameters are combined.

[0041] According to the rotating electric machine of the second embodiment, the coolant flow path includes an orifice, in front of the injection hole, where the inner diameter of the coolant flow path is smaller than that of the front and rear ends, an intake port for drawing gas from the space, and a mixing chamber for mixing the coolant and the gas. Since the coolant passing through the orifice flows quickly and its pressure is reduced, the air pressure in the mixing chamber can be reduced to atmospheric pressure or below. By mixing the coolant and air in the mixing chamber and then injecting it from the injection hole, the coolant can be dispersed over a wide area. Furthermore, the coolant flow path includes a swirl chamber, in front of the injection hole, that generates a swirling flow along the inner wall. Therefore, the coolant flowing into the swirl chamber flows in a spiral pattern along the inner wall of the swirl chamber, allowing the coolant to be sprayed throughout the space within the housing so as to spread from the injection hole. Furthermore, since the injection hole is a nozzle of a spray device, the coolant can be sprayed in a finer mist using the spray device, thereby evenly cooling the inside of the housing.

[0042] Third Embodiment A rotating electric machine according to the third embodiment will be described below, focusing on the differences from the first embodiment. Fig. 10 is a cross-sectional view of the rotating electric machine 300 taken along a plane including the central axis O of the shaft 22. Fig. 11 is a cross-sectional view taken along the line D-D in Fig. 10, showing only a cross section of the housing cylindrical portion 331 and the coil end 12E. When a certain amount or more of the coolant C is floating in the space R within the housing 303, some of the coolant C will also adhere to the inner wall of the housing 303, which has little effect on cooling the coil end 12E.

[0043] Therefore, the coolant C adhering to the inner wall of the housing 3 is collected for the coil end 12E of the rotating electric machine 300 and dripped onto the coil end 12E. To achieve this, a protrusion 331D that protrudes vertically downward is provided on the inner wall of the housing cylindrical portion 331, vertically above the coil end 12E when the rotating electric machine 300 is in an operating state.

[0044] Furthermore, by arranging the housing internal flow path 31P outside the protrusion 331D in the radial direction X, the temperature of the inner wall surface of the housing 303 near the protrusion 331D is lowered. Therefore, when water or a refrigerant is used as the coolant C, the phase-changed gas is more likely to condense than on other inner wall surfaces, and the amount of coolant C dripping onto the coil end 12E can be increased.

[0045] In addition, the inner wall of the housing cylindrical portion 331 may be sloped toward the protrusion 331D, or a thin groove may be provided to guide the coolant C to the protrusion 331D by capillary action, thereby increasing the amount of coolant C dripping onto the coil end 12E.

[0046] FIG. 12 shows a modified example of the housing cylindrical portion 331 and corresponds to FIG. 11 . In addition to the protrusion 331D1 located vertically upward (at 12 o'clock) in FIG. 12 , protrusions 331D2 and 331D3 are also located at the 2 o'clock and 10 o'clock positions relative to the coil end 12E. By arranging the protrusions 331D2 and 331D3, the coolant C flowing down along the annular inner wall surface of the housing cylindrical portion 331 can be collected by the protrusions 331D1 to 331D3, thereby increasing the amount of coolant C that drips onto the coil end 12E. Furthermore, by dispersing the drip points onto the coil end 12E in the circumferential direction Y, an additional cooling effect can be provided uniformly in the circumferential direction Y.

[0047] FIG. 13 is a cross-sectional view showing a modified example of the housing cylindrical portion 331 and the protruding portion 331D, and is a partial cross-sectional view perpendicular to the axial direction Z. When the housing cylindrical portion 331 is molded by die-casting, providing a protruding portion having a different thickness can lead to internal voids, which can reduce strength. Therefore, the reduction in strength can be avoided by molding the housing cylindrical portion 331 and the protruding portion 331D separately and then, for example, as shown in FIG. 13, by inserting the protruding portion 331D from the axial direction Z using a slit SL provided in the housing cylindrical portion 331. The above description of the protruding portion 331D does not limit the shape, position, or number of the protruding portion 331D, and the shape, position, and number of the protruding portion 331D may be freely changed as needed.

[0048] According to the rotating electric machine of the third embodiment, the inner wall of the housing has a protrusion that protrudes vertically downward above the coil end in an operating state, so that liquid droplets collect on the protrusion located directly above the coil end. By dripping these droplets onto the coil end, an additional cooling effect can be achieved.

[0049] Fourth Embodiment A rotating electric machine according to a fourth embodiment will now be described, particularly with regard to a configuration for stabilizing the flow rate of coolant sprayed from the rotor 20. Fig. 14 is a plan view of an end plate 423 of the rotor 20 according to the fourth embodiment, as seen from the outside in the axial direction Z. Fig. 15 is a cross-sectional view perpendicular to the axial direction Z of the rotor core 21 and permanent magnets M according to the present embodiment. Fig. 16 is a cross-sectional view of a hollow flow path portion of a shaft 422 and a main portion of the end plate 423 according to the fourth embodiment, in which the shaft 422 and the end plate 423 are cut along a plane including the central axis O of the shaft 422. Fig. 17 is a cross-sectional view taken along the line E-E of Fig. 16.

[0050] As explained above, if a structure in which the cross-sectional area of ​​the flow path outlet is reduced as shown in Figures 2 and 7 to 9 is adopted in order to spread the coolant C sprayed from the rotor 20 toward the space R within the housing 3 over a wider area than the hole diameter of the injection hole 21H, when the rotor 20 rotates at high speed, the coolant C may be pressed against the inner wall surface of the rotor core flow path 21P by centrifugal force, resulting in a decrease in the amount of coolant sprayed from the injection hole 21H.

[0051] The flow rate of the coolant into the injection holes and the coolant flow passages may be adjusted according to the rotational speed of the rotor by electrical control or by structural features.

[0052] However, the method of switching the flow paths by control has concerns such as the complexity of the control logic, increased costs due to the addition of electrical components, and worsening of the electricity consumption due to the power consumption, etc. Therefore, in the fourth embodiment, an adjustment method based on the structural characteristics of the rotor 20 is used, which utilizes the rotation of the rotor 20 itself.

[0053] 2 and 7 to 9, the end plate 423 is provided with both small-diameter injection holes 21H and injection holes 421H that are not tapered and have a larger diameter than the injection holes 21H. When the rotor 20 is driven at low rotation speeds, the coolant C is sprayed mainly from the small-diameter injection holes 21H, and when the rotor 20 is driven at high rotation speeds, the coolant C is sprayed mainly from the large-diameter injection holes 421H. Note that the injection holes 421H may be slightly tapered as long as their diameter is larger than that of the injection holes 21H.

[0054] The rotor core internal flow passages 21P are provided in the axial direction Z along the permanent magnet M on both sides of the permanent magnet M in the circumferential direction Y, and are connected to the injection holes 21H of the end plates 423 described in Fig. 14. The rotor core internal flow passage 421P is provided in the axial direction Z along the permanent magnet M at the center of the circumferential direction Y and inside in the radial direction X, and is connected to the injection holes 421H.

[0055] The shaft internal flow path 422P extending in the axial direction Z from one end of the shaft 422 is provided with, at the end opposite the inlet of the shaft internal flow path 422P, a cylindrical branch pipe 422Q having the same axis as the central axis O of the shaft internal flow path 422P and a first flow path opening IN1 with a smaller diameter than the shaft internal flow path 422P.

[0056] The first flow path port IN1, which is the inlet of the branch pipe 422Q, is connected to a plurality of first end plate internal flow paths 423P1 extending radially outward within the end plate 423, and each is further connected to the rotor core internal flow path 21P (first coolant flow path system). The second flow path port IN2, formed between the outer circumferential surface of the branch pipe 422Q and the inner circumferential surface of the shaft internal flow path 422P, is connected to a plurality of second end plate internal flow paths 423P2 extending radially outward within the end plate 423, and each is further connected to the rotor core internal flow path 421P (second coolant flow path system). The cross-sectional area of ​​the first flow path port IN1 cut perpendicular to the axial direction Z is sufficiently larger than the cross-sectional area of ​​the second flow path port IN2 cut perpendicular to the axial direction Z.

[0057] In addition, the diameter of each injection hole provided in the end plate 423 connected to the shaft internal flow path 422P may be made smaller than the diameter of each injection hole in the end plate provided on the opposite side in the axial direction Z, so that the amount of coolant C sprayed from both end plates is equal.

[0058] Furthermore, the number of first end plate internal flow paths 423P1 and second end plate internal flow paths 423P2 may be reduced by connecting a plurality of end plate internal flow paths in the circumferential direction inside the end plate.

[0059] According to the rotating electric machine of the fourth embodiment, the rotor is provided with a plurality of coolant flow path systems made up of the coolant flow paths, and the flow rate of the coolant flowing through each coolant flow path system can be adjusted according to the rotational speed of the rotor, so that a constant amount of coolant can be supplied to the space within the housing regardless of the rotational speed. Further, the shaft of the rotor is provided with an internal shaft flow passage extending axially through the shaft from one end side of the shaft, and the internal shaft flow passage is provided with a branch pipe at an end opposite to the inlet of the internal shaft flow passage, the branch pipe having the same axis as the internal shaft flow passage and having a first flow passage opening with a smaller diameter than the internal shaft flow passage, the first flow passage opening being connected to a first coolant flow passage system which is one of the plurality of coolant flow passage systems, and a second flow passage opening formed between the outer peripheral surface of the branch pipe and the inner peripheral surface of the internal shaft flow passage is connected to a second coolant flow passage system which is one of the plurality of coolant flow passage systems, so that when the rotor 20 is driven at low rotation speed, the internal shaft flow passage 422P of the shaft 422 is filled with coolant, and a large amount of coolant C flows into the first coolant flow passage system through the first flow passage opening IN1 in accordance with the ratio of the cross-sectional areas of the first flow passage opening IN1 and the second flow passage opening IN2. On the other hand, when the rotor 20 is driven at high rotational speeds, centrifugal force causes the coolant C to flow in a circular pattern, adhering to the inner wall of the shaft internal flow passage 422P. This allows a large amount of coolant C to flow into the second coolant flow passage system from the outer peripheral second flow passage port IN2. This allows the coolant flow passage to be adjusted according to the rotor rotation speed without requiring electrical control to switch the flow passage. Furthermore, since the cross-sectional area of ​​the first flow passage port cut perpendicular to the axial direction is larger than the cross-sectional area of ​​the second flow passage port cut perpendicular to the axial direction, a large amount of coolant can be sprayed through the large-diameter first flow passage port located in the center of the shaft internal flow passage at low rotational speeds. Furthermore, since the diameter of the injection holes in the second coolant flow passage system is larger than the diameter of the injection holes in the first coolant flow passage system, the coolant can be sprayed into the space within the housing at high rotational speeds.

[0060] Embodiment 5. An electric vehicle according to embodiment 5 will now be described. In the previous embodiments 1 to 4, the space R within the housing of the rotating electrical machine is filled with sprayed coolant C, and the coil ends 12E are uniformly cooled.

[0061] In this fifth embodiment, an electric vehicle equipped with an electromechanical integrated vehicle drive system will be described, which is equipped with a refrigerant circulation system that uses part of the refrigerant used in the car air conditioner on the drive system side to cool the motor, inverter, and battery, and lubricate the gears.

[0062] Fig. 18 is a block diagram showing an example of a cooling circuit of an electric vehicle 50. Arrow AR1 in Fig. 18 indicates the flow path of liquid refrigerant C1. Arrow AR2 in Fig. 18 indicates the flow path of low-temperature gas-liquid multiphase refrigerant C1. Arrow AR3 in Fig. 18 indicates the flow path of high-temperature gas-liquid multiphase refrigerant C1. Normally, refrigerant C1 in the car air conditioner CA circulates through condenser 51, receiver 52, expansion valve 53, evaporator 54, and compressor 55, and returns to condenser 51.

[0063] In the fifth embodiment, a portion of the low-temperature, low-pressure gas-liquid mixed-phase refrigerant C1 sprayed from the expansion valve 53 of the car air conditioner CA is supplied to the inverter 71 and the battery 80, dissipating heat generated therein. The refrigerant C1 passing through the inverter 71 is thought to be heated to approximately 60°C to 80°C, but is thought to have a sufficient cooling effect on the coil 12 and permanent magnets M, which reach temperatures of 100°C or higher within the motor 100. The temperature of the refrigerant C1 (cooling liquid C) increases in this order from the upstream side to the downstream side.

[0064] The gas-liquid mixed phase refrigerant C1 supplied to the motor 100 is widely dispersed within the housing 3 of the motor 100 from each of the injection holes 21H, 31H having the tip structures shown in Figures 2 and 7 to 9, and floats at a high density in the internal space R, thereby evenly contacting the coil ends 12E and providing a uniform cooling effect.

[0065] At this time, the gas-liquid mixed-phase refrigerant C1 is more likely to break into droplets than a single-phase liquid when sprayed into the space R within the housing 3 of the motor 100. In addition, the heat generated at the coil end 12E causes a portion of the refrigerant C1 to change phase from a liquid state to a gas state, which is expected to have a significant heat removal effect due to the latent heat of evaporation.

[0066] The refrigerant that has reached a high-temperature gas-liquid two-phase state inside the motor 100 is then supplied to the gear box 72, where it functions as a gear lubricant. After completing its cooling and lubricating functions in the drive system, the refrigerant C1 is supplied to the compressor 55 and returned to the circulation system of the car air conditioner CA.

[0067] FIG. 19 is a block diagram showing another example of a cooling circuit for electric vehicle 50 according to a modification of the fifth embodiment. Arrow AR4 in FIG. 19 indicates the flow path of low-temperature refrigerant C2. Arrow AR5 in FIG. 19 indicates the flow path of high-temperature refrigerant C2. Refrigerant C2 used in motor 100, inverter 71, and battery 80 desirably has rust-resistant and insulating properties, and a specific example is cooling oil such as ATF. Therefore, two types of refrigerant are used: refrigerant C1 for car air conditioner CA and refrigerant C2 for driving, and refrigerant C2 is cooled by refrigerant C1 in heat exchanger 60.

[0068] Since the drive side shares one type of refrigerant C2, it is possible to reduce the number of parts such as the liquid feed pump, exchanger, refrigerant storage tank, etc., thereby enabling cost and weight reduction. In particular, in the case of an electromechanical integrated configuration, the motor 100, inverter 71, and gear box 72 are integrated into one casing 70, and by sharing the refrigerant C2, the refrigerant flow path provided in the casing 70 can be simplified.

[0069] As described above, by exchanging heat via heat exchanger 60 between each component within electric vehicle 50, for example, refrigerant C1 for car air conditioner CA and refrigerant C2 that cools motor 100, inverter 71, and battery 80 that make up the vehicle drive system, even if the refrigerant itself is not shared, it is possible to mutually utilize the cooling circuits made up of each refrigerant, select the optimal type of refrigerant for each component in electric vehicle 50 as a whole, and build a cooling mechanism that is capable of transferring heat as a whole, thereby optimizing the cooling mechanism to a high level.

[0070] 19, as well as the example described using Fig. 18, the flow paths of the cooling circuit are the same in that a relatively low-temperature refrigerant C1 is used for the car air conditioner CA in the electric vehicle 50, and the refrigerant C2 used to cool the inverter 71 is also used to cool the motor 100 and the gear box 72, with the temperature increasing relatively downstream. By adopting these configurations, as described above, it is possible to systematize cooling methods suitable for the temperatures of the components to be cooled, thereby performing efficient cooling.

[0071] In the example described with reference to Figures 18 and 19, the refrigerant supplied to the electromechanical integrated structure is circulated through the inverter 71, motor 100, and gearbox 72 in that order, but other circulation paths may also be used.

[0072] Furthermore, the motor applied to this embodiment is a motor that is combined with a rotating electric machine equipped with a refrigerant diffusion means in the refrigerant flow path described in embodiments 1 to 4, and the refrigerant used to cool the rotating electric machine is mutually utilized with the cooling circuit that cools and lubricates each component in the electric vehicle, thereby reducing the number of parts in the entire electric vehicle and realizing a cooling system that optimizes the cooling mechanism.However, it is not necessarily intended to be applied only to rotating electric machines equipped with a refrigerant diffusion means, and it may also be combined with a general rotating electric machine that uses a refrigerant to cool the rotating electric machine.

[0073] Even when combining such general rotating electric machines, the refrigerant circulation system described in this embodiment can be applied so that the refrigerant used to cool the rotating electric machine and the cooling circuit that cools and lubricates each component in the electric vehicle can be mutually utilized, and the basic effects obtained in this embodiment described above can be obtained in common.

[0074] The electric vehicle according to the fifth embodiment includes a refrigerant circulation system that uses at least a portion of the coolant for the rotating electric machine as a refrigerant. By supplying a portion of the coolant for the rotating electric machine to other components installed inside the vehicle, a liquid feed pump, a heat exchanger, a coolant storage tank, and the like can be shared among multiple components, thereby reducing the cost and weight of the electric vehicle. Furthermore, the electric vehicle includes an inverter, a battery, and a gear that drive the rotating electric machine. The coolant for the rotating electric machine is used as a refrigerant for at least one of cooling the inverter, cooling the battery, and lubricating the gear. Since the rotating electric machine, inverter, battery, and gear are often located close to each other, a common system for supplying coolant to them can reduce the number of components. This is also effective for an electromechanical axle in which the motor, inverter, and gear are integrated into a single casing. Furthermore, since a refrigerant for a car air conditioner is used as the coolant for the rotating electric machine, the gas-liquid multiphase refrigerant used in air conditioners is excellent as a coolant for a motor because it has a large heat removal effect due to the latent heat of evaporation caused by the phase change from a liquid state to a gas state. Furthermore, the present invention includes a rotating electric machine and a refrigerant circulation system using at least a portion of the coolant, and the refrigerant for the car air conditioner, the refrigerant cooling the inverter that drives and controls the rotating electric machine, and the coolant for the rotating electric machine circulate in this order from upstream to downstream, with the temperatures of the refrigerant and the coolant increasing sequentially from upstream to downstream. This allows for an electric vehicle to be obtained that efficiently cools the temperatures of each component to be cooled throughout the vehicle by systematizing appropriate cooling. Furthermore, the cooling circuit containing the refrigerant for the car air conditioner and the cooling circuit that cools the inverter that drives and controls the rotating electric machine are equipped with a refrigerant circulation system that allows heat transfer via a heat exchanger. This allows for the selection of an optimal type of refrigerant for each component in the electric vehicle, thereby building a cooling mechanism that allows heat transfer as a whole and optimizing the cooling mechanism of the electric vehicle at a high level.

[0075] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are anticipated within the scope of the technology disclosed in each embodiment. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0076] 100, 300 Rotating electric machine (motor), 10 Stator, 11 Stator core, 12 Coil, 12E Coil end, 20 Rotor, 20P Rotor coolant flow path, 21 Rotor core, 21H, 21H1, 21H2, 221H, 221H2, 221H3, 421H Injection hole, 21P, 421P Flow path inside rotor core, OF Orifice, 22, 422 Shaft, 22P, 422P Flow path inside shaft, 422Q Branch pipe, 23, 423, 24 End plate, 23P Flow path inside end plate, 423P1 First flow path inside end plate, 423P2 Second flow path inside end plate, 3, 303 Housing, 31, 331 Housing cylindrical portion, 31P, 32P Flow path inside housing, 32 Housing end plate, 31H, 231H Injection hole, 331D, 331D1, 331D2, 331D3 protrusion, 5 bearing, 50 electric vehicle, 51 condenser, 52 receiver, 53 expansion valve, 54 evaporator, 55 compressor, 55 compressor, 60 heat exchanger, 70 casing, 71 inverter, 72 gearbox, 80 battery, AR1, AR2, AR3, AR4, AR5 arrow, C coolant, C1, C2 refrigerant, CA car air conditioner, G gap, IN intake port, IN1 first flow path port, IN2 second flow path port, M permanent magnet, O central axis, PA nozzle part, R space, RM mixing chamber, RM2 swirl chamber, SL slit, X radial direction, Y circumferential direction, Z axial direction.

Claims

1. A rotating electric machine comprising a housing, a stator having a stator core fixed to the housing and a coil wound around the stator core, and a rotor having a rotor core and a shaft rotatably supported by the housing, wherein at least one of the rotor or the housing has a coolant flow path for supplying coolant to the coil ends of the coil, and a hole diameter of an injection hole for injecting the coolant from the coolant flow path into a space within the housing is smaller than a diameter of the coolant flow path.

2. The rotating electric machine according to claim 1, wherein the injection hole has a tapered shape.

3. The rotating electric machine according to claim 1 or 2, wherein the injection hole is a nozzle of a spraying device.

4. The rotating electric machine according to claim 1 or 2, wherein the coolant flow path includes an orifice in front of the injection hole where an inner diameter of the coolant flow path is smaller than that before and after, an air inlet for sucking gas from the space, and a mixing chamber for mixing the coolant and the gas.

5. The rotating electric machine according to claim 1 or 2, wherein the coolant flow path includes a swirling chamber in front of the injection hole for generating a swirling flow along an inner wall.

6. The rotating electric machine according to any one of claims 1 to 5, wherein an inner wall of the housing, directly above the coil ends in an operating state, has a protruding portion protruding downward vertically.

7. The rotating electric machine according to any one of claims 1 to 6, wherein the rotor includes a plurality of coolant flow path systems formed by the coolant flow paths, and a flow rate of the coolant flowing through each coolant flow path system can be adjusted according to a rotational speed of the rotor.

8. A shaft of the rotor includes an inner flow path within the shaft extending axially through the shaft from one end side of the shaft. The inner flow path within the shaft has the same axis as an axis of the inner flow path at an end opposite to an inlet of the inner flow path within the shaft, and includes a branched pipe having a first flow port with a smaller diameter than the inner flow path within the shaft. The first flow port is connected to a first coolant flow path system which is one of the plurality of coolant flow path systems. A second flow port formed between an outer peripheral surface of the branched pipe and an inner peripheral surface of the inner flow path within the shaft is connected to a second coolant flow path system which is one of the plurality of coolant flow path systems.

9. The rotating electrical machine according to claim 8, wherein a cross-sectional area obtained by cutting the first coolant flow port perpendicular to the axial direction is larger than a cross-sectional area obtained by cutting the second coolant flow port perpendicular to the axial direction.

10. The rotating electrical machine according to claim 8 or 9, wherein a hole diameter of the injection hole of the second coolant flow path system is larger than a hole diameter of the injection hole of the first coolant flow path system.

11. The rotating electrical machine according to any one of claims 1 to 10, wherein the rotor core of the rotor includes an inner flow path for the coolant along a permanent magnet accommodated in the rotor core.

12. The rotating electrical machine according to any one of claims 1 to 11, wherein the rotor core is composed of a plurality of laminated steel plates or a plurality of laminated steel plates and end plates, and resin is filled between the laminations of the laminated steel plates and between the laminated steel plates and the end plates.

13. An electric vehicle comprising a refrigerant circulation system that uses at least a part of the coolant of the rotating electrical machine according to any one of claims 1 to 12 as a refrigerant.

14. The electric vehicle according to claim 13, comprising an inverter, a battery, and a gear for driving the rotating electrical machine, wherein the coolant of the rotating electrical machine is used as a refrigerant for at least one of cooling the inverter, cooling the battery, and lubricating the gear.

15. An electric vehicle that uses a refrigerant for a car air conditioner as the coolant of the rotating electrical machine according to any one of claims 1 to 12.

16. An electric vehicle comprising the rotating electrical machine according to any one of claims 1 to 12 and a refrigerant circulation system that uses at least a part of the coolant, wherein a refrigerant for a car air conditioner constituting the refrigerant circulation system, a refrigerant for cooling an inverter that drives and controls the rotating electrical machine, and the coolant of the rotating electrical machine circulate side by side from the upstream side to the downstream side in this order, and the temperature of the refrigerant and the coolant becomes sequentially higher from the upstream side to the downstream side.

17. The electric vehicle comprises a refrigerant circulation system in which a cooling circuit including the refrigerant for the car air conditioner according to claim 15 and a cooling circuit for cooling an inverter that drives and controls the rotating electrical machine are capable of heat transfer via a heat exchanger.

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