Drive device

Abstract

One aspect of a drive device according to the present invention comprises a motor. An in-core flow path is provided inside a stator core of the motor. The in-core flow path has a circumferential flow path that extends along the circumferential direction, and a plurality of axial flow paths that extend along the axial direction. The stator core has a plurality of plates that are stacked in the axial direction. Openings that penetrate in the axial direction are provided in at least a portion of the plurality of plates. The plurality of plates overlap in the axial direction, whereby the openings each constitute a portion of the in-core flow path. The plurality of plates include a first plate and a second plate that are adjacent in the axial direction. In the first plate, a first opening is provided as the opening, and in the second plate, a second opening is provided as the opening. The circumferential flow path includes: a first flow path section that is provided inside the first opening; a second flow path section that is provided inside the second opening; and a connection flow path section that is provided in a portion in which one circumferential end of the first opening and the other circumferential end of the second opening overlap in the axial direction.

Description

Drive device

[0001] The present invention relates to a drive device. This application claims priority based on Japanese Patent Application No. 2024-208293 filed in Japan on November 29, 2024, and the contents thereof are incorporated herein by reference.

[0002] There are cases where a cooling structure is required for the stator core to cool the stator core. Patent Document 1 discloses a structure in which, in addition to through-holes for fastening, through-holes are provided in the ears for fastening the stator core, and cooling oil is caused to flow through the through-holes.

[0003] Japanese Unexamined Patent Application Publication No. 2020-114085

[0004] The flow paths provided in the conventional stator core were unable to cool the entire stator core.

[0005] One aspect of the present invention aims to provide a drive device capable of cooling the entire stator core in view of the above circumstances.

[0006] One embodiment of the drive device of the present invention comprises a motor having a rotor rotatable about a central axis and a stator surrounding the rotor from the radially outer side. The stator has a stator core having a core internal flow path inside, and coils mounted on the stator core. The core internal flow path has a circumferential flow path extending along the circumferential direction and a plurality of axial flow paths extending along the axial direction. The stator core has a plurality of plates stacked in the axial direction. The plurality of axial flow paths are connected to the circumferential flow path and are aligned in the circumferential direction. At least a portion of the plurality of plates is provided with an opening that penetrates in the axial direction. The openings each constitute a part of the core internal flow path when the plurality of plates overlap in the axial direction. The plurality of plates include a first plate and a second plate that are adjacent to each other in the axial direction. The first plate is provided with a first opening that extends along the circumferential direction as the opening. The second plate is provided with a second opening that extends along the circumferential direction and a portion of which overlaps with the first opening in the axial direction as the opening. The circumferential flow path comprises a first flow path portion provided inside the first opening, a second flow path portion provided inside the second opening, and a connecting flow path portion provided in the portion where one circumferential end of the first opening and the other circumferential end of the second opening overlap in the axial direction.

[0007] According to one aspect of the present invention, a drive device capable of cooling the entire stator core can be provided.

[0008] Figure 1 is a schematic diagram of the drive device of the first embodiment. Figure 2 is a partial cross-sectional view of the drive device of the first embodiment. Figure 3 is a cross-sectional view of the drive device of the first embodiment along the first plate. Figure 4 is a cross-sectional view of the drive device of the first embodiment along the second plate. Figure 5 is a cross-sectional view of the drive device of the first embodiment along the third plate. Figure 6 is a schematic diagram showing the internal flow path of the core of the first embodiment. Figure 7 is a front view of the internal flow path of the core of the first embodiment. Figure 8 is a schematic cross-sectional view of the internal flow path of the core of the first embodiment along the circumferential direction. Figure 9 is a front view of the internal flow path of the core of the second embodiment. Figure 10 is a front view of the internal flow path of the core of the third embodiment. Figure 11 is a partially enlarged view of the internal flow path of the core of the third embodiment. Figure 12 is a partially enlarged view of the internal flow path of the core of the fifth embodiment. Figure 13 is a front view of the internal flow path of the core of the sixth embodiment.

[0009] The following description of a drive system according to an embodiment of the present invention will be given with reference to the drawings. In the following description, the direction of gravity will be defined and explained based on the positional relationship when the drive system 100 is mounted on a vehicle located on a horizontal road surface. The drawings will also show an XYZ coordinate system as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, the direction in which the Z axis extends is the vertical direction. The direction in which the X axis extends is the longitudinal direction of the vehicle on which the drive system 100 is mounted. The direction in which the Y axis extends is perpendicular to both the X and Z axes and is parallel to the central axis J of the motor 2. The direction in which the Y axis extends is the left-right direction of the vehicle, that is, the vehicle width direction.

[0010] In the following explanation, unless otherwise specified, the direction parallel to the central axis J of motor 2 (the Y-axis direction) will simply be referred to as the "axial direction." Furthermore, the radial direction centered on the central axis J will simply be referred to as the "radial direction," and the circumferential direction centered on the central axis J will simply be referred to as the "circumferential direction."

[0011] Each figure will show the circumferential direction θ as appropriate. In the following explanation, "one side of the circumferential direction" means the side (+θ) to which the arrow indicating the circumferential direction θ points, and "the other side of the circumferential direction" means the opposite side (-θ) to which the arrow indicating the circumferential direction θ points.

[0012] [First Embodiment] <Drive Unit> Figure 1 is a schematic diagram of the drive unit 100 of the first embodiment. The drive unit 100 of this embodiment is mounted on and used as a power source for vehicles that use a motor as a power source, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs).

[0013] The drive unit 100 comprises a motor 2, a housing 6 having a housing space 6A for housing the motor 2, a fluid cooler 9 fixed to the outer surface of the housing 6, and a fluid O that accumulates in the housing space 6A. The drive unit 100 may also further include a power transmission unit (not shown) that reduces the rotation of the motor 2 and outputs it to the outside.

[0014] The drive unit 100 is provided with a flow path 90 through which fluid O flows. The fluid O circulates within the housing 6 by passing through the flow path 90. The flow path 90 includes an external piping flow path 92, an internal wall flow path 91, an internal base flow path 94, an intermediate flow path 95, and an internal core flow path 80. The external piping flow path 92 is provided within the piping connected to the drive unit 100. The internal wall flow path 91, the internal base flow path 94, and the intermediate flow path 95 are provided in the housing 6. The internal core flow path 80 is provided in the stator core 32 of the motor 2.

[0015] The fluid cooler 9 is located in the path of the flow path 90, between the external piping flow path 92 and the wall-internal flow path 91. The fluid cooler 9 is connected to the base-internal flow path 94 via the wall-internal flow path 91. The fluid cooler 9 cools the fluid O that flows in from the external piping flow path 92 and supplies it to the wall-internal flow path 91. A pump (not shown) is also provided in the path of the flow path 90 to pump the fluid O in the flow path 90.

[0016] In this embodiment, fluid O functions as a coolant to cool the motor 2. Alternatively, fluid O may function as a lubricant to lubricate the bearing B and the power transmission section (not shown). In this case, it is preferable to use an oil equivalent to a relatively low-viscosity automatic transmission fluid (ATF) for fluid O to perform both lubricating and cooling functions.

[0017] In this specification, the "channel cross-sectional area" of each channel refers to the cross-sectional area of ​​the channel at a cross-section perpendicular to the typical flow direction of the fluid flowing through the channel.

[0018] <Motor> Motor 2 in this embodiment is a three-phase AC motor. Motor 2 in this embodiment combines the functions of an electric motor and a generator. Motor 2 only needs to have either the function of an electric motor or the function of a generator.

[0019] The motor 2 comprises a rotor 20 that rotates about a central axis J extending horizontally, a stator 30 located radially outside the rotor 20, and a pair of bearings B that rotatably support the rotor 20. The motor 2 in this embodiment is an inner rotor type motor.

[0020] <Rotor> The rotor 20 is rotatable about its central axis J. The rotor 20 rotates when an alternating current is passed through the stator 30. The rotor 20 has a shaft 21, a rotor core 24, and a conductor portion 25.

[0021] The shaft 21 extends axially about a central axis J. The shaft 21 is rotatably supported in the housing 6 via a pair of bearings B. The rotor core 24 is constructed, for example, by stacking multiple laminations. The rotor core 24 is cylindrical and extends axially. The rotor core 24 is provided with multiple rotor slots 24a that penetrate axially. The multiple rotor slots 24a are arranged at equal intervals in the circumferential direction. The conductor portion 25 has multiple conductor bars 25a and a pair of end rings 25b. The conductor portion 25 is made of a metal material with excellent conductivity, such as a copper alloy.

[0022] The conductor bars 25a extend along the axial direction. Multiple conductor bars 25a are each positioned in the rotor slots 24a. A pair of end rings 25b are positioned on one axial side and the other side of the rotor core 24, respectively. The end rings 25b connect the multiple conductor bars 25a to each other.

[0023] The motor 2 in this embodiment is an induction motor that rotates the rotor 20 by generating electromagnetic induction in the rotor 20. However, the motor 2 may also be a synchronous motor. In this case, the rotor 20 may have permanent magnets.

[0024] <Stator> The stator 30 surrounds the rotor 20 from the radially outer side. The stator 30 has a stator core 32, a coil 31 wound around the stator core 32, and an insulator (not shown) interposed between the stator core 32 and the coil 31. The stator 30 is fixed to the housing 6.

[0025] The stator core 32 is annular in shape with a central axis J at its center. The stator core 32 surrounds the rotor 20 from the radially outer side. The stator core 32 faces the rotor 20 with a radial gap in between. The stator core 32 is also provided with an internal flow path 80.

[0026] Figure 2 is a partial cross-sectional view of the drive unit 100 in a cross-section perpendicular to the axial direction. As shown in Figure 2, the stator core 32 has a plurality of laminations 40a stacked in the axial direction. The plurality of laminations 40a are fixed to each other by means of crimping, welding, or bonding. The laminations 40a are made of a magnetic metal material. The metal material constituting the laminations 40a is, for example, an amorphous metal.

[0027] The stator core 32 of this embodiment is composed of multiple laminations 40a with different contour shapes (four types in this embodiment). Here, the contour of the lamination 40a refers to the shape as viewed from the axial direction (i.e., the thickness direction) of the lamination 40a. One or more laminations 40a with the same contour shape are stacked in the axial direction to form a plate body 40. That is, one plate body 40 is composed of one or more laminations 40a. The stator core 32 is composed of multiple plate bodies 40.

[0028] The plurality of plates 40 include a first plate 41, a second plate 42, a third plate 43, and a fourth plate 44. In this embodiment, the first plate 41, the second plate 42, the third plate 43, and the fourth plate 44 each have a plurality of laminations 40a with the same contour shape. Note that the first plate 41, the second plate 42, the third plate 43, and the fourth plate 44 may each be composed of a single lamination. The plurality of plates 40 are arranged in the order of the third plate 43, the second plate 42, and the first plate 41, from the other side in the axial direction (-Y) to the one side in the axial direction (+Y). That is, the first plate 41 and the second plate 42 are adjacent in the axial direction.

[0029] Figures 3 to 5 are cross-sectional views of the drive device 100 along a plane perpendicular to the axial direction of this embodiment. As shown in Figures 3 to 5, various shapes of openings 51, 52, and 53 are provided in at least a portion of the multiple plate bodies 40 that constitute the stator core 32. The openings 51, 52, and 53 each penetrate the plate body 40 in the axial direction. The openings 51, 52, and 53 are connected to each other by the overlapping of the multiple plate bodies 40 in the axial direction, and each constitutes a part of the internal core flow path 80. Furthermore, as will be described later, the inlet flow path 81 of the internal core flow path 80 is provided in the through hole 35h. Therefore, the openings 51, 52, and 53 each constitute a part of the through hole 35h, the connecting flow path 82, or the core cooling flow path 83 by the overlapping of the multiple plate bodies 40 in the axial direction. Furthermore, as will be described later, a portion of the through hole 35h constitutes the inlet flow path 81. According to this embodiment, the complex shape of the core's internal flow path 80, which provides excellent cooling efficiency, can be easily tilted by the shape of the openings 51, 52, and 53. This prevents the temperature of the stator 30 from becoming too high.

[0030] As shown in Figure 3, the first plate 41 is provided with a plurality (12 in this embodiment) of first openings 51 and one third opening 53 as described above. The plurality of first openings 51 are each arc-shaped and extend in the circumferential direction with a uniform width dimension. The plurality of first openings 51 are arranged at equal intervals in the circumferential direction.

[0031] The third opening 53 extends radially outward from one of the multiple first openings 51A. The radially outward end of the third opening 53 is located on the projection 35 of the stator core 32 and connects to the through hole 35h.

[0032] As shown in Figure 4, the second plate 42 is provided with a plurality (12 in this embodiment) of second openings 52 and a plurality (12 in this embodiment) of fourth openings 54 as described above. Each of the plurality of second openings 52 is an arc shape extending in the circumferential direction with a uniform width dimension. The width dimension of the second opening 52 is approximately equal to the width dimension of the first opening 51. The circumferential length dimension of the second opening 52 is approximately equal to the circumferential length dimension of the first opening 51. When viewed from the axial direction, the radii of curvature and the centers of curvature of the plurality of first openings 51 and second openings 52 are approximately equal to each other. The plurality of second openings 52 are arranged at equal intervals in the circumferential direction. The second openings 52 are offset from the first openings 51 in the circumferential direction. When viewed from the axial direction, the second openings 52 are positioned between two adjacent first openings 51 in the circumferential direction. A portion of the second opening 52 overlaps with a portion of the first opening 51 when viewed from the axial direction.

[0033] Multiple fourth openings 54 are arranged at equal intervals in the circumferential direction. The fourth openings 54 are located between two adjacent second openings 52 in the circumferential direction. The fourth openings 54 in this embodiment are circular holes. The diameter of the fourth openings 54 is smaller than the width dimension of the first openings 51 and the second openings 52.

[0034] As shown in Figure 5, the third plate 43 is provided with a plurality (24 in this embodiment) of fifth openings 55 as described above. The plurality of fifth openings 55 are arranged at equal intervals in the circumferential direction. The fifth openings 55 are round holes. The diameter of the fifth opening 55 is equal to the diameter of the fourth opening 54. Therefore, the diameter of the fifth opening 55 is smaller than the width dimension of the first opening 51 and the second opening 52. Note that the shape and dimensions of the first opening 51, the second opening 52, the third opening 53, the fourth opening 54, and the fifth opening 55 are not limited to this embodiment.

[0035] All 12 fourth openings 54 shown in Figure 4 overlap with 12 of the 24 fifth openings 55 shown in Figure 5 when viewed from the axial direction. As a result, all fourth openings 54 are connected to a fifth opening 55. Among the fifth openings 55, those that do not overlap with the fifth openings 55 when viewed from the axial direction and those that do overlap with the fifth openings 55 when viewed from the axial direction are arranged alternately in the circumferential direction.

[0036] As shown in Figure 3, the stator core 32 has a core back portion (cylindrical portion) 33, a plurality of teeth portions 34, and a plurality of protrusions 35.

[0037] The core back portion 33 is cylindrical, surrounding the central axis J. In this embodiment, the core back portion 33 is cylindrical with the central axis J as its center. However, the shape of the core back portion 33 is not limited to this embodiment.

[0038] Each of the multiple teeth 34 protrudes radially inward from the inner circumferential surface of the core back portion 33. The multiple teeth 34 are arranged at equal intervals in the circumferential direction. Each tooth 34 faces the rotor 20 with a radial gap between them. The end faces on one axial side (+Y) of the multiple teeth 34 are coplanar with the end face on one axial side (+Y) of the core back portion 33. Similarly, the end faces on the other axial side (-Y) of the multiple teeth 34 are coplanar with the end face on the other axial side (-Y) of the core back portion 33.

[0039] Multiple protrusions 35 project radially outward from the outer circumferential surface of the core back portion 33. The multiple protrusions 35 are arranged at equal intervals in the circumferential direction. The stator core 32 of this embodiment is provided with four protrusions 35 arranged at equal intervals in the circumferential direction. As a result, the stator core 32 has a substantially rectangular shape when viewed from the axial direction, making it easier to fit into the housing space 6A of the housing 6. The number of protrusions 35 provided on the stator core 32 may be three or fewer, or five or more. Two of the multiple protrusions 35 are located above the central axis J, and the other two are located below the central axis J. The end faces of the multiple protrusions 35 on one axial side (+Y) are arranged on the same plane as the end face of the core back portion 33 on one axial side (+Y). Similarly, the end faces of the multiple protrusions 35 on the other axial side (-Y) are arranged on the same plane as the end face of the core back portion 33 on the other axial side (-Y).

[0040] Each of the multiple protrusions 35 is provided with a through hole 35h. The through hole 35h penetrates the protrusion 35 in the axial direction. Bolts 8 for fixing the stator core 32 to the housing 6 are inserted into the through holes 35h.

[0041] As shown in Figure 2, the bolt 8 extends in the axial direction. The bolt 8 has a shaft portion 8b that is inserted into the through hole 35h, and a head portion 8a located at the other axial end (-Y) of the shaft portion 8b. The shaft portion 8b also has a cylindrical portion 8c and a threaded portion 8d arranged coaxially. In other words, the bolt 8 has a cylindrical portion 8c, a threaded portion 8d, and a head portion 8a.

[0042] The male thread portion 8d is located at one axial end (+Y) of the shaft portion 8b. That is, the male thread portion 8d is located on one axial side (+Y) of the cylindrical portion 8c. The male thread portion 8d is inserted into the female thread portion 66a of the housing 6. In this way, the bolt 8 fixes the stator core 32 to the housing 6.

[0043] As shown in Fig. 1, the plurality of coils 31 are each attached to the teeth portion 34 via an insulator (not shown). That is, the coil 31 is attached to the stator core 32. Each coil 31 has a pair of coil ends 31a that protrude on one axial side (+Y) and the other axial side (-Y) with respect to the stator core 32. The coil 31 is electrically connected to an external power source (not shown). For example, an alternating current is passed through the coil 31 from the external power source.

[0044] <Core internal flow path> Fig. 6 is a schematic diagram of the core internal flow path 80 of the present embodiment. The core internal flow path 80 of the present embodiment has an inlet flow path 81, a connecting flow path 82, and a core cooling flow path 83.

[0045] The inlet flow path 81 leads to a flow path (relay flow path 95, see Fig. 1) provided outside the stator core and guides the fluid O into the stator core 32. The connecting flow path 82 extends radially inward from the inlet flow path 81. The core cooling flow path 83 is connected to the radially inner end of the connecting flow path 82. That is, the connecting flow path 82 connects the inlet flow path 81 and the core cooling flow path 83.

[0046] The core cooling flow path 83 cools the stator core 32. The core cooling flow path 83 is connected to the connecting flow path 82. The core cooling flow path 83 has one circumferential flow path 84 that extends along the circumferential direction and a plurality of axial flow paths 85 that extend along the axial direction. That is, the core internal flow path 80 has a circumferential flow path 84 and a plurality of axial flow paths 85.

[0047] <Inlet flow path> As shown in Fig. 2, the inlet flow path 81 is provided in the through hole 35h of one protrusion 35A among the plurality of protrusions 35. In the stator core 32 of the present embodiment, the inlet flow path 81 is provided in one protrusion 35A that is located above the central axis J and is arranged closest to the fluid cooler 9 among the plurality of protrusions 35. Note that a plurality of inlet flow paths 81 may be provided in the stator core 32. In this case, the plurality of inlet flow paths 81 are provided in the through holes 35h of different protrusions 35. That is, the inlet flow path 81 is provided in at least one of the plurality of protrusions 35. In the following description, the description will be made focusing on the protrusion 35A in which the inlet flow path 81 is provided among the plurality of protrusions 35.

[0048] When the motor 2 is driven, a magnetic flux path (magnetic circuit) is formed in the stator core 32. In the stator core 32, the protruding portion 35A is located radially outside the core back portion 33. Therefore, it is difficult to form a magnetic circuit in the protruding portion 35A and it is difficult for the magnetic flux density to increase. As a result, even if a flow path is formed inside the protruding portion 35A, it is difficult for the magnetic resistance of the stator core 32 to increase. According to the present embodiment, by providing the inlet flow path 81 in the protruding portion 35A, it is possible to suppress an increase in the magnetic resistance of the stator core 32 due to the inlet flow path 81.

[0049] Further, according to the present embodiment, by providing the inlet flow path 81 inside the through hole 35h into which the bolt 8 is inserted, it is possible to suppress an increase in the size of the protruding portion 35A as compared with the case where a hole for the inlet flow path 81 is separately provided in the protruding portion 35A. As a result, it is possible to reduce the size and weight of the drive device 100.

[0050] As shown in FIG. 3, the inlet flow path 81 of the present embodiment is provided in the protruding portion 35A located above the central axis J among the plurality of protruding portions 35. According to the present embodiment, since the inlet flow path 81 can be arranged above the central axis J, after the fluid O flows into the stator core 32 from the inlet flow path 81, the fluid O can be spread over the entire stator core 32 using gravity downstream of the inlet flow path 81.

[0051] Further, the inlet flow path 81 of the present embodiment is provided in the protruding portion 35A that is closest to the fluid cooler 9 among the plurality of protruding portions 35. According to the present embodiment, the flow path connecting the fluid cooler 9 and the inlet flow path 81 can be shortened, and the fluid O cooled by the fluid cooler 9 and reduced in temperature can be supplied to the inside of the stator core 32 in a low-temperature state. As a result, the cooling efficiency of the stator 30 can be improved.

[0052] As shown in Figure 2, the stator core 32 of this embodiment is constructed by stacking multiple laminations 40a. Therefore, when forming the internal flow channels 80 in the stator core 32, there is a concern that fluid O may flow between the laminations 40a, causing a decrease in the pressure of the fluid O. In particular, such a pressure decrease tends to be significant in the inlet channel 81 located on the upstream side of the internal flow channels 80. According to this embodiment, the inlet channel 81 is provided in a through hole 35h into which a bolt 8 that fixes the stator core 32 to the housing 6 is inserted. Therefore, the surface pressure applied between the laminations 40a around the inlet channel 81 can be increased by the fastening force of the bolt 8, thereby suppressing the flow of fluid O between the laminations 40a.

[0053] In this embodiment, the entire through-hole 35h overlaps with the head 8a of the bolt 8 when viewed from the axial direction. At the interface of the multiple laminations 40a, the surface pressure is particularly increased in the region that overlaps with the head 8a when viewed from the axial direction as the bolt 8 is fastened. According to this embodiment, by sufficiently increasing the surface pressure between the laminations 40a around the through-hole 35h, the inflow of fluid O between the laminations 40a can be suppressed even more reliably.

[0054] The through hole 35h provided in the protruding portion 35A has a large-diameter portion 35ha and a small-diameter portion 35hb. Both the large-diameter portion 35ha and the small-diameter portion 35hb are circular when viewed from the axial direction, and have different diameters from each other.

[0055] The large-diameter portion 35ha opens to one side in the axial direction (+Y). The large-diameter portion 35ha is connected to the connecting passage 82. The small-diameter portion 35hb is connected to the other end of the large-diameter portion 35ha in the axial direction (-Y) and opens to the other side in the axial direction (-Y). The small-diameter portion 35hb has a smaller diameter than the large-diameter portion 35ha. The diameter of the small-diameter portion 35hb is slightly larger than the diameter of the shaft portion 8b of the bolt 8 inserted into the through hole 35h, and smaller than the diameter of the seating surface of the head 8a of the bolt 8.

[0056] The inlet passage 81 is a passage formed inside the large-diameter portion 35ha. More specifically, the inlet passage 81 is provided in the space between the inner circumferential surface of the large-diameter portion 35ha and the outer circumferential surface of the shaft portion 8b of the bolt 8. The inlet passage 81 guides fluid O into the stator core 32 from an opening on one axial side (+Y) of the large-diameter portion 35ha and supplies fluid O to the connecting passage 82 at the other axial side (-Y) end of the large-diameter portion 35ha. According to this embodiment, by providing a large-diameter portion 35ha with a larger diameter than the small-diameter portion 35hb in the through hole 35h, a large cross-sectional area of ​​the inlet passage 81 can be secured.

[0057] In this embodiment, a portion of the fluid O flowing into the through hole 35h flows into the space between the inner circumferential surface of the small-diameter portion 35hb and the outer circumferential surface of the shaft portion 8b of the bolt 8, and accumulates between the inner circumferential surface of the small-diameter portion 35hb and the outer circumferential surface of the bolt 8. This suppresses the formation of an air layer between the shaft portion 8b and the bolt 8, and allows heat to be transferred from the stator core 32 to the fluid O even in the small-diameter portion 35hb.

[0058] In the bolt 8 of this embodiment, the diameter of the cylindrical portion 8c is larger than the thread diameter of the male thread portion 8d. Therefore, when viewed from the axial direction, the entire outer shape of the male thread portion 8d is positioned inside the outer shape of the cylindrical portion 8c. According to this embodiment, compared to the case where the diameter of the cylindrical portion is smaller than the thread diameter of the male thread portion, the gap between the inner circumferential surface of the small diameter portion 35hb and the outer circumferential surface of the cylindrical portion 8c can be narrowed. This reduces the volume of fluid O flowing between the small diameter portion 35hb and the cylindrical portion 8c, and prevents excess fluid O from accumulating inside the stator core 32.

[0059] In this embodiment, the material or shape of the bolt 8 that passes through the inlet channel 81 may differ from that of the other bolts 8. For example, it is preferable that the bolt 8 that passes through the inlet channel 81 is made of a material with superior thermal conductivity compared to the other bolts 8.

[0060] <Connection channel> The connection channel 82 extends radially inward from the through hole 35h. In particular, the connection channel 82 connects to the other axial end (-Y) of the large diameter portion 35ha. As shown in Figure 3, the connection channel 82 is provided inside the third opening 53 of the first plate body 41.

[0061] As shown in Figure 6, the connecting channel 82 in this embodiment extends radially and connects the inlet channel 81 and the circumferential channel 84 of the core. The core cooling channel 83 can efficiently cool the coil 31 by positioning it close to the coil 31, which is a heat-generating element. On the other hand, it is preferable to position the inlet channel 81 away from the coil 31 in order to reduce the magnetic resistance of the stator core 32. For this reason, the inlet channel 81 is positioned radially outside the circumferential channel 84. According to this embodiment, since the connecting channel 82 extends radially, it can connect the inlet channel 81 and the core cooling channel 83, which are positioned radially inside and outside the channel.

[0062] <Circumferential Flow Channel> The circumferential flow channel 84 extends along the circumferential direction centered on the central axis J. The circumferential flow channel 84 in this embodiment is annular when viewed from the axial direction. The circumferential flow channel 84 in this embodiment has a plurality of first flow channel sections 84a, a plurality of second flow channel sections 84b, and a plurality of connecting flow channel sections 84c.

[0063] As shown in Figure 3, the first flow channel 84a is provided inside the first opening 51 of the first plate body 41. As shown in Figure 4, the second flow channel 84b is provided inside the second opening 52 of the second plate body 42. As described above, the first plate body 41, in which the first flow channel 84a is provided, and the second plate body 42, in which the second flow channel 84b is provided, are arranged adjacent to each other in the axial direction. Therefore, the first flow channel 84a and the second flow channel 84b are arranged offset from each other in the axial direction.

[0064] Figure 7 is a front view of the internal flow channel 80 of this embodiment. In Figure 7, the second flow channel 84b is shown by a dashed line. As shown in Figure 7, the multiple first flow channel sections 84a are arranged at equal intervals in the circumferential direction. Similarly, the multiple second flow channel sections 84b are arranged at equal intervals in the circumferential direction, with at least a portion of them offset from the first flow channel sections 84a in the circumferential direction. Viewed from the axial direction, the second flow channel section 84b is positioned between two circumferentially adjacent first flow channel sections 84a. The end of the second flow channel section 84b on one side (+θ) in the circumferential direction overlaps with the end of the first flow channel section 84a located on one side (+θ) in the circumferential direction of two circumferentially adjacent first flow channel sections 84a, when viewed from the axial direction, and these are connected. The end of the second flow channel 84b on the other side (-θ) in the circumferential direction overlaps, when viewed from the axial direction, with the end of the first flow channel 84a on one side (+θ) of the first flow channel 84a located on the other side (-θ) in the circumferential direction of two adjacent first flow channel sections 84a in the circumferential direction, and these are connected.

[0065] In this embodiment, the first flow channel 84a and the second flow channel 84b each extend along the circumferential direction. Therefore, the fluid O flowing through the first flow channel 84a and the second flow channel 84b flows in the circumferential direction. Furthermore, the cross-sectional area of ​​the flow channels of the first flow channel 84a and the second flow channel 84b is the area of ​​the cross-section perpendicular to the circumferential direction in each section.

[0066] Figure 8 is a schematic cross-sectional view of the internal core channel 80. In Figure 8, the circumferential direction θ is shown as a straight line in the left-right direction of the paper. As shown in Figure 8, the connecting channel section 84c is provided in the portion where the end of one side (+θ) in the circumferential direction of the first opening 51 and the end of the other side (-θ) in the circumferential direction of the second opening 52 overlap in the axial direction. Therefore, the connecting channel section 84c is provided at the boundary between the first plate 41 and the second plate 42.

[0067] Since the connecting channel section 84c is the part that connects the first channel section 84a and the second channel section 84b, which are arranged offset in the axial direction, the fluid O flowing through the connecting channel section 84c flows in the axial direction. Furthermore, the cross-sectional area of ​​the channel in the connecting channel section 84c is the area of ​​the cross-section perpendicular to the axial direction.

[0068] In this embodiment, the fluid O flowing through the circumferential channel 84 flows in the order of first channel section 84a, connecting channel section 84c, second channel section 84b, and connecting channel section 84c, repeating this sequence. As described above, the flow direction of the fluid O is circumferential in the first channel section 84a and the second channel section 84b, and axial in the connecting channel section 84c. Therefore, the fluid O flows alternately in the circumferential and axial directions. Furthermore, before and after the connecting channel section 84c, the fluid O changes its flow direction from circumferential to axial, and then changes its flow direction back to circumferential.

[0069] In this embodiment, the flow path cross-sectional area S3 of the connecting flow path section 84c is preferably 80% to 120% of the flow path cross-sectional area S1 of the first flow path section 84a and the flow path cross-sectional area S2 of the second flow path section 84b. According to this embodiment, the increase or decrease in the flow path cross-sectional area of ​​the circumferential flow path 84 before and after the connecting flow path section 84c can be minimized. This reduces the pressure loss in the circumferential flow path 84 and allows the fluid O to flow efficiently through the circumferential flow path 84. Furthermore, as will be described later, a plurality of axial flow paths 85 arranged in the circumferential direction are connected to the circumferential flow path 84. According to this embodiment, by reducing the pressure loss in the circumferential flow path 84, the flow rate of the fluid O flowing into the plurality of axial flow paths 85 can be made uniform.

[0070] <Axial Flow Channels> As shown in Figure 6, the axial flow channels 85 of this embodiment extend linearly in the axial direction. In addition, the axial flow channels 85 of this embodiment are arranged at equal intervals in the circumferential direction. Each of the multiple axial flow channels 85 is connected to the circumferential flow channel 84 at one end on the axial side (+Y). The axial flow channels 85 open to the other end face on the axial side (-Y) of the stator core 32 at the other end on the axial side (-Y).

[0071] Some of the multiple axial flow channels 85 are connected to the first flow channel section 84a, and other parts are connected to the second flow channel section 84b. Of the multiple axial flow channels 85, those connected to the first flow channel section 84a and those connected to the second flow channel section 84b are arranged alternately in the circumferential direction.

[0072] In this embodiment, a portion of the axial flow path 85 is located inside the fourth opening 54 of the second plate body 42 (see Figure 4). Another portion of the axial flow path 85 in this embodiment is located inside the fifth opening 55 of the third plate body 43 (see Figure 5). As shown in Figure 8, of the multiple axial flow paths 85, those connected to the second flow path portion 84b of the second plate body 42 are located only inside the fifth opening 55 of the third plate body 43. On the other hand, of the multiple axial flow paths 85, those connected to the first flow path portion 84a of the first plate body 41 are located not only inside the fifth opening 55 of the third plate body 43 but also inside the fourth opening 54 of the second plate body 42. That is, of the multiple axial flow paths 85, those connected to the first flow path portion 84a of the first plate body 41 are flow paths that connect the fifth opening 55 and the fourth opening 54.

[0073] As shown in Figure 8, in the circumferential flow path 84, the portion that connects to the axial flow path 85 is designated as the first connection portion 84p. That is, each circumferential flow path 84 in this embodiment has a plurality of first connection portions 84p connected to the axial flow path 85. The plurality of first connection portions 84p are arranged at equal intervals in the circumferential direction. One first connection portion 84p is provided in one first flow path portion 84a. The first connection portion 84p of the first flow path portion 84a is located in the circumferential center of the first flow path portion 84a. Similarly, one first connection portion 84p is provided in one second flow path portion 84b. The first connection portion 84p of the second flow path portion 84b is located in the circumferential center of the second flow path portion 84b.

[0074] In the circumferential flow path 84 of this embodiment, the first connecting portion 84p is located between two adjacent connecting flow path portions 84c in the circumferential direction. That is, each of the multiple first connecting portions 84p is provided at a position different from the connecting flow path portions 84c in the circumferential direction. The fluid O flowing through the circumferential flow path 84 changes its flow direction at the connecting flow path portions 84c. As a result, the pressure of the fluid O flowing through the circumferential flow path 84 decreases at the first connecting portion 84p. According to this embodiment, by arranging the first connecting portion 84p offset from the connecting flow path portions 84c in the circumferential direction, the decrease in the flow rate of the fluid O flowing into the axial flow path 85 via the first connecting portion 84p can be suppressed.

[0075] According to the drive device 100 of this embodiment, the internal flow path 80 provided in the stator core 32 has a circumferential flow path 84 extending along the circumferential direction, and a plurality of axial flow paths 85 that are arranged in the circumferential direction and extend axially from the circumferential flow path 84. Therefore, the circumferential flow path 84 supplies fluid O to the plurality of axial flow paths 85, and the stator core 32 can be cooled by the axial flow paths 85.

[0076] Furthermore, according to the drive device 100 of this embodiment, a circumferential flow path 84 can be formed by overlapping and connecting the first opening 51 and the second opening 52 provided in adjacent plates 40 in the axial direction. Therefore, compared to the case where a circumferential flow path is formed by an opening in a single plate, a circumferentially long circumferential flow path 84 can be formed while ensuring the rigidity of each plate 40. In particular, the circumferential flow path 84 of this embodiment is annular. Such a circumferential flow path 84 cannot be formed by an opening provided in a single plate. That is, according to this embodiment, an annular circumferential flow path 84 can be easily formed when viewed from the axial direction.

[0077] The circumferential flow path 84 in this embodiment has a plurality of first flow path sections 84a, a plurality of second flow path sections 84b, and a plurality of connecting flow path sections 84c. Therefore, compared to the case in which the circumferential flow path has only one first flow path section and one second flow path section, the first flow path section 84a and the second flow path section 84b can be arranged in a well-balanced manner in the circumferential and axial directions. As a result, when the motor 2 is driven, the magnetic paths inside the stator core 32 can be arranged in a well-balanced manner, and the driving of the motor 2 can be stabilized.

[0078] In this embodiment, the circumferential flow path 84 is annular when viewed from the axial direction. Furthermore, in this embodiment, the multiple axial flow paths 85 are arranged at equal intervals in the circumferential direction. According to this embodiment, these features make it possible to suppress the imbalance of the magnetic path inside the stator core 32 when the motor 2 is driven.

[0079] In this embodiment, the axial flow path 85 extends linearly in the axial direction. According to this embodiment, the axial flow path 85 can be easily formed by overlapping the openings provided in the multiple laminations in the axial direction. The axial flow path 85 may extend both in the axial direction and in the circumferential direction. That is, the axial flow path 85 may extend skewed along the axial direction or in a spiral shape.

[0080] As shown in Figure 1, in this embodiment, the fluid O flows out of the stator core 32 from the other axial end (-Y) of the axial flow path 85. The fluid O that flows out of the stator core 32 accumulates in the lower region of the containment space 6A. The fluid accumulated in the lower region of the containment space 6A is sent to the fluid cooler 9 via the external piping flow path 92 by a pump (not shown) and used again to cool the stator 30.

[0081] Furthermore, some of the fluid O flowing out of the stator core 32 comes into contact with the coil ends 31a of the coil 31 and the rotor 20 as it reaches the lower region of the containment space 6A. As a result, the fluid O cools the coil ends 31a and the rotor 20.

[0082] In this embodiment, the axial flow path 85 extends only from the circumferential flow path 84 to the other axial side (-Y) and opens to the other axial side (-Y) of the stator core 32. However, the axial flow path 85 may extend from the circumferential flow path 84 to both axial sides and open to both end faces of the stator core 32. In this case, it becomes possible to cool the pair of coil ends 31a located on both axial sides by directing the fluid O onto them.

[0083] In this embodiment, the case in which the circumferential flow path 84 is located at one axial end (+Y) of the stator core 32 has been described. In this case, the inlet flow path 81 located at one axial end (+Y) can be brought closer to the circumferential flow path 84, reducing the pressure loss of the fluid O in the inlet flow path 81 and allowing the fluid O to be smoothly supplied to the circumferential flow path 84. However, the circumferential flow path 84 may also be located near the axial center of the stator core 32, or it may be located at the other axial end (-Y) of the stator core 32.

[0084] <Housing> As shown in Figure 1, the housing 6 has a housing body 60 and a cover 69 fixed to the housing body 60. The housing space 6A for housing the motor 2 is the space enclosed by the housing body 60 and the cover 69. The housing body 60 and the cover 69 are made of, for example, die-cast aluminum.

[0085] The housing body 60 has a cylindrical portion 61 that surrounds the central axis J and extends in the axial direction, a bottom portion 62 that closes the opening on one axial side (+Y) of the cylindrical portion 61, and a plurality of base portions (fixing portions) 65 to which the stator 30 is fixed. The housing body 60 opens on the other axial side (-Y). The opening of the housing body 60 is covered by a cover 69.

[0086] The cylindrical portion 61 surrounds the motor 2 from the radially outward direction. In this embodiment, the cylindrical portion 61 is a rectangular tube that follows the outer shape of the stator core 32 when viewed from the axial direction. A fluid cooler 9 is fixed to the outer surface 60f of the cylindrical portion 61 that faces radially outward.

[0087] A wall-internal flow path 91 is provided in the cylindrical portion 61. The wall-internal flow path 91 opens at the outer surface 60f of the cylindrical portion 61 and connects to the internal flow path of the fluid cooler 9, which is fixed to the outer surface 60f. The wall-internal flow path 91 also connects to the base-internal flow path 94 at its radially inner end.

[0088] The bottom portion 62 and the cover 69 are plate-shaped, each extending along a plane perpendicular to the axial direction. The bottom portion 62 and the cover 69 face each other in the axial direction. The bottom portion 62 is located on one axial side (+Y) of the motor 2. The cover 69 is located on the other axial side (-Y) of the motor 2. The bottom portion 62 and the cover 69 each hold a bearing B. The bottom portion 62 and the cover 69 support the shaft 21 via the bearing B.

[0089] <Base Section> The base section 65 is positioned in the housing space 6A. The base section 65 is provided on the inner wall surface of the housing body 60. The base section 65 protrudes inward from the surface of the cylindrical section 61 that faces radially inward. The base section 65 also protrudes in the other axial direction (-Y) from the surface of the bottom section 62 that faces the other axial direction (-Y).

[0090] Multiple base portions 65 are arranged at equal intervals in the circumferential direction. The housing body 60 is provided with the same number of base portions 65 as the protrusions 35 of the stator core 32. That is, the housing 6 of this embodiment has four base portions 65. A protrusion 35 is fixed to each of the four base portions 65. In the following description, we will focus on the base portion 65A that is fixed to the protrusion 35A on which the inlet flow path 81 is provided.

[0091] As shown in Figure 2, the base portion 65A is provided with a base surface (fixed surface) 65f facing the other axial direction (-Y), a hole 66 opening in the base surface 65f, and a base internal flow path 94 connected to the hole 66. A bolt 8 is inserted into the hole 66.

[0092] The base surface 65f is a flat surface extending along a plane perpendicular to the axial direction. The base surface 65f is in contact with the surface of the projection 35A facing one side of the axial direction (+Y). The stator core 32 is fastened to the base surface 65f.

[0093] The hole 66 extends in the axial direction. The hole 66 has a female threaded portion 66a and an open hole portion 66b. The female threaded portion 66a is the region in the hole 66 where female threads are provided on the inner circumferential surface. The male threaded portion 8d of the bolt 8 is screwed into the female threaded portion 66a.

[0094] The opening portion 66b is located on the other axial side (-Y) from the female thread portion 66a. The opening portion 66b opens into the base surface 65f. The inner circumferential surface of the opening portion 66b faces the shaft portion 8b of the bolt 8 with a gap between them.

[0095] An internal flow channel 94 of the base opens to the inner circumferential surface of the opening portion 66b. In other words, the internal flow channel 94 of the base connects to the hole portion 66. As a result, fluid O flows into the interior of the hole portion 66 from the internal flow channel 94 of the base. Furthermore, the interior of the hole portion 66 functions as a flow channel. That is, an intermediate flow channel 95 is arranged inside the hole portion 66. The intermediate flow channel 95 is provided in the space between the inner circumferential surface of the hole portion 66 and the outer circumferential surface of the shaft portion 8b of the bolt 8.

[0096] The opening of the hole 66 faces the through hole 35h of the protruding portion 35A. As a result, the relay channel 95 provided inside the hole 66 is connected to the inlet channel 81 provided inside the through hole 35h. The relay channel 95 guides the fluid O from the base channel 94 to the inlet channel 81.

[0097] In this embodiment, the internal flow path 94 of the base is connected to the hole 66, thereby supplying fluid O to the inside of the through hole 35h of the protruding portion 35A via the hole 66. In other words, according to the housing 6 of this embodiment, fluid O can be supplied to the inside of the stator core 32.

[0098] Furthermore, in the stator core 32 of this embodiment, fluid O is supplied to the through hole 35h of the protruding portion 35A via the relay channel 95. Therefore, the through hole 35h of the protruding portion 35A can function as the inlet channel 81 of the core internal channel 80. As a result, the inlet channel 81, which tends to have a large channel cross-sectional area, is not formed in the core back portion 33, and the increase in the magnetic resistance of the stator core 32 due to the core internal channel 80 can be suppressed.

[0099] Furthermore, according to this embodiment, the through hole 35h into which the bolt 8 is inserted is used as an inlet passage 81. This allows the surface pressure applied to the area around the opening of the hole 66 in the base surface 65f and the area around the opening of the through hole 35h on the end face of the protruding portion 35A to be increased by the fastening force of the bolt 8. This prevents the fluid O from leaking out from between the base surface 65f and the end face of the protruding portion 35A.

[0100] In particular, when viewed from the axial direction, the entire through hole 35h and the entire hole portion 66 overlap the seating surface of the bolt head 8a. This allows the surface pressure in the area around the opening of the hole portion 66 on the base surface 65f and the area around the opening of the through hole 35h on the end face of the projection 35A to be particularly increased when the bolt 8 is fastened. As a result, leakage of fluid O from between the base surface 65f and the end face of the projection 35A can be more effectively suppressed.

[0101] In this embodiment, the diameter of the opening 66b is larger than the root diameter of the female thread 66a. Therefore, when viewed from the axial direction, the entire female thread 66a is positioned inside the opening 66b. Also, the base internal flow path 94 opens to the inner circumferential surface of the opening 66b. According to this embodiment, a large cross-sectional area of ​​the intermediate flow path 95 provided between the inner circumferential surface of the opening 66b and the outer circumferential surface of the shaft 8b can be secured. As a result, the fluid O can be smoothly guided from the base internal flow path 94 to the core internal flow path 80 by the intermediate flow path 95.

[0102] In this embodiment, a portion of the male thread portion 8d of the bolt 8 is positioned only in an area of ​​10 mm or less from the other axial end (-Y) of the opening hole 66b. Therefore, the shaft portion 8b positioned inside the opening hole 66b is almost entirely a cylindrical portion 8c. As a result, the flow of fluid O in the intermediate channel 95 can be prevented from being disturbed by the threads of the male thread portion 8d, and the reduction in the amount of fluid O supplied to the core channel 80 can be suppressed.

[0103] In this embodiment, the cross-sectional area Sa of the relay channel 95 is greater than or equal to the cross-sectional area Sb of the channel 94 within the base. According to this embodiment, pressure loss in the channel can be suppressed at the connection between the channel 94 within the base and the relay channel 95, and the reduction in the amount of fluid O supplied to the stator core 32 can be suppressed.

[0104] Furthermore, in this embodiment, it is even more preferable that the cross-sectional area Sa of the relay channel 95 is equal to the cross-sectional area Sb of the channel 94 within the base. In this case, pressure loss in the channel can be further suppressed at the connection between the channel 94 within the base and the relay channel 95.

[0105] The fluid O flowing through the relay channel 95 flows in the axial direction. Therefore, the cross-sectional area Sa of the relay channel 95 is the cross-sectional area of ​​the relay channel 95 in a cross-section perpendicular to the axial direction. More specifically, the cross-sectional area Sa of the relay channel 95 is the difference between the cross-sectional area of ​​the opening 66b and the cross-sectional area of ​​the shaft 8b of the bolt 8 in a cross-section perpendicular to the axial direction.

[0106] On the other hand, the flow channel 94 within the base of this embodiment extends linearly in a plane perpendicular to the axial direction. The flow direction of the fluid O flowing through the flow channel 94 within the base is the direction in which the flow channel 94 extends. Therefore, the flow channel cross-sectional area Sb of the flow channel 94 within the base is the cross-sectional area of ​​the flow channel 94 in a cross section perpendicular to the direction in which the flow channel 94 extends.

[0107] In this embodiment, the internal flow path 94 of the base opens at one end of the inner surface of the opening hole 66b on the axial side (+Y). For example, if the internal flow path of the base opens at the inner surface of the opening hole near the axial center of the opening hole, a portion of the fluid O flowing from the internal flow path into the opening hole will branch to both sides in the axial direction inside the opening hole, making turbulence likely to occur. In this case, the pressure loss in the flow path becomes large at the connection point between the internal flow path of the base and the intermediate flow path. In contrast, according to this embodiment, the fluid O that flows into the inside of the opening hole 66b flows only on the other axial side (-Y), thus reducing the pressure loss. As a result, the reduction in the amount of fluid O supplied to the stator core 32 can be suppressed.

[0108] [Second Embodiment] Figure 9 is a front view of the internal flow path 180 of the second embodiment. In Figure 9, the second flow path section 184b is shown by a dashed line. In the descriptions of each embodiment described below, components that are the same as those in the embodiments already described are denoted by the same reference numerals, and their descriptions are omitted.

[0109] As shown in Figure 9, the core internal flow path 180 of this embodiment has an inlet flow path 81, a connecting flow path 82, and a core cooling flow path 183, similar to the embodiment described above. Although not shown in the figure, the core internal flow path 180 is constructed by overlapping multiple plate bodies, each having an opening, in the axial direction, similar to the embodiment described above. The core cooling flow path 183 has one circumferential flow path 184 extending along the circumferential direction and multiple axial flow paths 85 extending along the axial direction. The circumferential flow path 184 of this embodiment is annular when viewed from the axial direction.

[0110] In this embodiment, the circumferential flow path 184 has one first flow path section 184a, one second flow path section 184b, and two connecting flow path sections 184c.

[0111] The first flow channel 184a is an arc shape extending 180° in the circumferential direction with respect to the central axis J. The end of the first flow channel 184a on one side in the circumferential direction (+θ) is designated as the first end 184aa, and the end on the other side in the circumferential direction (-θ) is designated as the second end 184ab. Connecting flow channel sections 184c are connected to the first end 184aa and the second end 184ab, respectively. The first end 184aa and the second end 184ab are located at approximately the same height as the central axis J.

[0112] The first flow channel 184a is connected to the connecting flow channel 82. In the circumferential flow channel 184, the portion that connects to the connecting flow channel 82 is designated as the second connecting portion 184q. That is, the first flow channel 184a in this embodiment has a second connecting portion 184q that connects to the connecting flow channel 82. The second connecting portion 184q is located in the circumferential direction between the first end portion 184aa and the second end portion 184ab.

[0113] The second flow channel 184b is an arc shape extending 180° in the circumferential direction with respect to the central axis J. The end of the second flow channel 184b on one circumferential side (+θ) is designated as the third end 184ba, and the end on the other circumferential side (-θ) is designated as the fourth end 184bb. The third end 184ba and the fourth end 184bb are located at approximately the same height as the central axis J.

[0114] The first end 184aa of the first channel section 184a and the fourth end 184bb of the second channel section 184b overlap each other when viewed from the axial direction. Also, the second end 184ab of the first channel section 184a and the third end 184ba of the second channel section 184b overlap each other when viewed from the axial direction.

[0115] The connecting channel section 184c is provided in the portion where the first channel section 184a and the second channel section 184b overlap and connect when viewed from the axial direction. One of the two connecting channel sections 184c is provided in the portion where the first end 184aa of the first channel section 184a and the fourth end 184bb of the second channel section 184b overlap when viewed from the axial direction. The other of the two connecting channel sections 184c is provided in the portion where the second end 184ab of the first channel section 184a and the third end 184ba of the second channel section 184b overlap when viewed from the axial direction. In other words, the circumferential end (+θ) of the first channel section 184a and the circumferential end (-θ) of the second channel section 184b are connected via the connecting channel section 184c. Furthermore, the other end (-θ) of the first flow channel 184a in the circumferential direction and the one end (+θ) of the second flow channel 184b in the circumferential direction are connected via a connecting flow channel 184c. The two connecting flow channel sections 184c are each located at approximately the same height as the central axis J. One of the two connecting flow channel sections 184c is positioned on the opposite side of the central axis J.

[0116] According to the circumferential flow path 184 of this embodiment, the number of connecting flow path sections 184c can be reduced compared to the first embodiment. The connecting flow path section 184c is the portion where the first flow path section 184a and the second flow path section 184b, which are arranged offset in the axial direction, are connected. The circumferential flow path 184 changes its flow direction from the circumferential direction to the axial direction before and after the connecting flow path section 184c, and then changes its flow direction back to the circumferential direction. For this reason, in the circumferential flow path 184, the pressure loss increases as the number of connecting flow path sections 184c increases. According to this embodiment, the pressure loss of the circumferential flow path 184 can be reduced by suppressing the number of connecting flow path sections 184c.

[0117] In the core channel 180 of this embodiment, the fluid O that flows from the connecting channel 82 into the first channel section 184a branches and flows to both sides at the second connection section 184q, on one side in the circumferential direction (+θ) and the other side in the circumferential direction (-θ). In the first channel section 184a of this embodiment, in the region on one side in the circumferential direction (+θ) from the second connection section 184q, the fluid O flows downward. On the other hand, in the first channel section 184a of this embodiment, in the region on the other side in the circumferential direction (-θ) from the second connection section 184q, the fluid O that flows into the second connection section 184q first flows upward, and then flows downward after passing the top of the circumferential channel 184. That is, the first channel section 184a of this embodiment extends downward as it moves from the second connection section 184q toward one side in the circumferential direction (+θ), and extends upward as it moves from the second connection section 184q toward the other side in the circumferential direction (-θ). In the first flow path section 184a of this embodiment, the path length from the second connection section 184q to the first end section 184aa is shorter than the path length from the second connection section 184q to the second end section 184ab.

[0118] Here, "path length" refers to the length of the path through which the fluid flows in the flow path. Therefore, the path length from the second connection point 184q to the first end point 184aa is the arc length centered on the central axis J between the second connection point 184q and the first end point 184aa. Similarly, the path length from the second connection point 184q to the second end point 184ab is the arc length centered on the central axis J between the second connection point 184q and the second end point 184ab.

[0119] In this embodiment, the fluid O flowing from the second connection portion 184q toward one side in the circumferential direction (+θ) tends to have a relatively large flow rate because it flows in the direction of gravity. On the other hand, the fluid O flowing from the second connection portion 184q toward the other side in the circumferential direction (-θ) tends to have a relatively small flow rate because it is flowing against gravity. Furthermore, the fluid O flowing through the circumferential flow path 184 experiences a large pressure loss at the connecting flow path portion 184c located at the first end 184aa and the second end 184ab of the first flow path portion 184a. For this reason, in the first flow path portion 184a, the pressure of the fluid O tends to be relatively high between the second connection portion 184q and the first end 184aa, and relatively low between the second connection portion 184q and the second end 184ab.

[0120] According to this embodiment, in the first flow path 184a, if the path from the second connection 184q, where the pressure of the fluid O tends to increase, to the first end 184aa becomes longer, the number of axial flow paths 85 connected in that path also increases, and the amount of fluid O common to these axial flow paths 85 also increases. According to this embodiment, by shortening the path length from the second connection 184q to the first end 184aa, it is possible to suppress the situation where too much fluid is supplied from that path to the axial flow paths 85, reducing the amount supplied to other axial flow paths 85. As a result, the uniformity of the fluid supplied to the multiple axial flow paths 85 can be improved.

[0121] In this embodiment, the case in which both the first flow channel 184a and the second flow channel 184b extend 180° in the circumferential direction has been described. However, one of the first flow channel 184a and the second flow channel 184b may extend more than 180°, while the other may extend less than 180°.

[0122] [Third Embodiment] Figure 10 is a front view of the core channel 280 of the third embodiment. In Figure 10, the second channel section 284b is shown by a dashed line. Compared with the second embodiment, the core channel 280 of this embodiment differs mainly in the positions of the first end 284aa and the second end 284ab of the first channel section 284a.

[0123] Similar to the second embodiment, the circumferential flow path 284 of this embodiment has a first flow path section 284a, a second flow path section 284b, and a connecting flow path section 284c. Also, similar to the second embodiment, the path length of the first flow path section 284a from the second connection section 284q to the first end section 284aa is shorter than the path length of the first flow path section 284a from the second connection section 284q to the second end section 284ab. This makes it possible to suppress the number of axial flow paths 85 connected to regions of the first flow path section 284a where pressure tends to increase due to gravity, and as a result, the uniformity of the flow rate supplied to the multiple axial flow paths 85 is improved.

[0124] Furthermore, in this embodiment, compared to the second embodiment, the first end portion 284aa is located above the second end portion 284ab. According to this embodiment, in the first flow path portion 284a, the path length from the second connection portion 284q to the first end portion 284aa can be made even shorter compared to the second embodiment. This makes it possible to further suppress the number of axial flow paths 85 connected to regions in the first flow path portion 284a where pressure tends to increase due to gravity, and to further improve the uniformity of the flow rate supplied to the multiple axial flow paths 85.

[0125] [Fourth Embodiment] Figure 11 is a partially enlarged view of the core channel 380 of the third embodiment. In Figure 11, the axial channel 85 is shown by a dashed line. The core channel 380 of this embodiment differs from the above-described embodiment mainly in the configuration of the connecting channel 382.

[0126] Similar to the embodiment described above, the internal core flow path 380 includes an inlet flow path 81, a connecting flow path 382, ​​and a core cooling flow path 383. The core cooling flow path 383 includes a circumferential flow path 84 and a plurality of axial flow paths 85. The circumferential flow path 84 in this embodiment has a plurality of first connecting portions 384p each connected to an axial flow path 85, and a single second connecting portion 384q connected to the connecting flow path 382. The plurality of first connecting portions 384p are arranged in a line in the circumferential direction.

[0127] In this embodiment, the connecting channel 382 extends with an inclination to one side in the circumferential direction as it extends radially outward from the circumferential channel 84. That is, the connecting channel 382 in this embodiment extends with an inclination to the radial direction.

[0128] In this embodiment, the second connection portion 384q is positioned between two adjacent first connection portions 384p in the circumferential direction. For example, if the first and second connection portions are positioned to overlap radially, the fluid flowing from the connection channel to the second connection portion in the circumferential channel will be concentrated and supplied to some of the axial channels via the first connection portion that overlaps with the second connection portion. In this embodiment, by positioning the second connection portion 384q between two adjacent first connection portions 384p in the circumferential direction, the first and second connection portions do not overlap radially. Therefore, the concentration of fluid supply to some of the axial channels 85 is suppressed, and the uniformity of the flow rate supplied to the multiple axial channels 85 is improved.

[0129] [Fifth Embodiment] Figure 12 is a partially enlarged view of the core channel 480 of the fifth embodiment. In Figure 12, the axial channel 485 is shown by a dashed line. The core channel 480 of this embodiment differs from the embodiment described above in the configuration of the connecting channel 482. Also, the core channel 480 of this embodiment differs from the embodiment described above in that it has a radial channel 486.

[0130] The core internal flow path 480 of this embodiment includes an inlet flow path 81, a plurality (two in this embodiment) of connecting flow paths 482, and a core cooling flow path 483.

[0131] In this embodiment, the multiple connecting channels 482 branch off from a single inlet channel 81. Each connecting channel 482 extends radially and connects to a circumferential channel 484. Of the two connecting channels 482, one extends with an inclination toward one side of the circumferential direction as it moves radially inward from the inlet channel 81, while the other extends with an inclination toward the other side of the circumferential direction as it moves radially inward from the inlet channel 81.

[0132] The core cooling channel 483 includes one circumferential channel 484 extending along the circumferential direction, a plurality of radial channels 486 extending along the radial direction, and a plurality of axial channels 485 extending along the axial direction.

[0133] The circumferential flow path 484 in this embodiment is not annular. The circumferential flow path 484 in this embodiment extends in a C-shape, interrupted at the portion facing the projection 35A in the radial direction. The radial flow path 486 extends radially inward from the circumferential flow path 484. Multiple radial flow paths 486 are arranged at equal intervals along the circumferential direction. The axial flow path 485 is connected to the radially inward end of the radial flow path 486.

[0134] The circumferential flow path 484 of this embodiment has a plurality of first connecting portions 484p each connected to the axial flow path 485 via the radial flow path 486, and a plurality of (two in this embodiment) second connecting portions 484q each connected to the connecting flow path 482. Similarly, the first connecting portions 484p are arranged in a line in the circumferential direction.

[0135] According to this embodiment, the circumferential flow path 484 has a plurality of second connection portions 484q to which different connecting flow paths 482 are connected. The plurality of second connection portions 484q are each arranged between adjacent first connection portions 484p in the circumferential direction. According to this embodiment, because the second connection portions 484q are arranged between adjacent first connection portions 484p in the circumferential direction, the first connection portions and the second connection portions do not overlap in the radial direction. Therefore, the concentration of fluid supply to some axial flow paths 485 is suppressed, and the uniformity of the flow rate supplied to the plurality of axial flow paths 485 is improved. Furthermore, according to this embodiment, since the core flow path 480 has a plurality of connecting flow paths 482 that are inclined toward one side and the other side in the circumferential direction, the fluid O can be guided to both sides in the circumferential direction in the circumferential flow path 484.

[0136] In this embodiment, the axial flow path 485 is located radially inward relative to the circumferential flow path 484. The radial flow path 486 extends radially and connects the circumferential flow path 484 and the axial flow path 485. By positioning the axial flow path 485 close to the teeth portion 34 on which the heating element coil 31 is mounted, the coil 31 can be efficiently cooled. On the other hand, it is preferable to position the circumferential flow path 484 away from the teeth portion 34 in order to reduce the magnetic resistance of the stator core 32. According to this embodiment, since the radial flow path 486 extends radially and connects the circumferential flow path 484 and the axial flow path 485, the axial flow path 485 can be positioned close to the teeth portion 34 while the circumferential flow path 484 can be positioned away from the teeth portion 34.

[0137] [Sixth Embodiment] Figure 13 is a front view of the core channel 580 of the sixth embodiment. The core channel 580 of this embodiment differs from the first embodiment in the configuration of the multiple axial channels 585a, 585b, and 585c.

[0138] The axial channels 585a, 585b, and 585c are arranged at equal intervals along the circumferential direction. The plurality of axial channels 585a, 585b, and 585c in this embodiment include a plurality (five in this embodiment) of first axial channels 585a, a plurality (fourteen in this embodiment) of second axial channels 585b, and a plurality (five in this embodiment) of third axial channels 585c. The first axial channels 585a, second axial channels 585b, and third axial channels 585c in this embodiment have different cross-sectional areas. The cross-sectional area of ​​the second axial channel 585b is larger than that of the first axial channel 585a. The cross-sectional area of ​​the third axial channel 585c is even larger than that of the second axial channel 585b.

[0139] The five first axial channels 585a are arranged in the circumferential direction. Similarly, the five third axial channels 585c are arranged in the circumferential direction. The five first axial channels 585a and the five third axial channels 585c are positioned on opposite sides of the central axis J. The fourteen second axial channels 585b are classified into two groups of seven. The seven second axial channels 585b in each group are positioned on opposite sides of the central axis J. In addition, the seven second axial channels 585b in each group are positioned between the five first axial channels 585a and the five third axial channels 585c in the circumferential direction.

[0140] The circumferential flow path 84 in this embodiment is annular with respect to the central axis J. The circumferential flow path 84 has a second connection portion 584q, a plurality of third connection portions 584r, a plurality of fourth connection portions 584t, and a plurality of fifth connection portions 584u.

[0141] The second connection part 584q is connected to the connection channel 82. The multiple third connection parts 584r are each connected to the first axial channel 585a. The multiple fourth connection parts 584t are each connected to the second axial channel 585b. The multiple fifth connection parts 584u are each connected to the third axial channel 585c.

[0142] The third connection section 584r is provided in the same number as the first axial flow path 585a (5 pieces). The fourth connection section 584t is provided in the same number as the second axial flow path 585b (14 pieces). The fifth connection section 584u is provided in the same number as the third axial flow path 585c (5 pieces).

[0143] The five third connecting portions 584r are arranged in the circumferential direction. One of the five third connecting portions 584r, located in the center, overlaps radially with the second connecting portion 584q. In the circumferential flow path 84, the region where multiple third connecting portions 584r are arranged is closest to the second connecting portion 584q. On the other hand, the region where multiple fifth connecting portions 584u are arranged is furthest from the second connecting portion 584q. Furthermore, the distance between the region where multiple fourth connecting portions 584t are arranged and the second connecting portion 584q is greater than the distance between multiple third connecting portions 584r and the distance between multiple fifth connecting portions 584u and the distance between multiple fourth connecting portions 584t and the second connecting portion 584q is greater than the distance between multiple third connecting portions 584r and the distance between multiple fifth connecting portions 584u and the distance between multiple third connecting portions 584u and the distance between multiple fourth connecting portions 584t and the second connecting portion 584q is greater than the distance between multiple third connecting portions 584r and the second connecting portion 584q.

[0144] In the circumferential flow path 84 of this embodiment, the path length from the second connection part 584q to the third connection part 584r is shorter than the path length from the second connection part 584q to the fourth connection part 584t. In the circumferential flow path 84 of this embodiment, the path length from the second connection part 584q to the fourth connection part 584t is shorter than the path length from the second connection part 584q to the fifth connection part 584u.

[0145] In the circumferential flow path 84, the fluid O flowing in from the connecting flow path 82 branches and flows to both sides in the circumferential direction at the second connection point 584q. This fluid O is supplied in greater quantities to the axial flow path that is closer to the second connection point 584q. For this reason, the first axial flow path 585a, which is located closest to the second connection point 584q, tends to receive the most fluid O. The second axial flow path 585b, which is located further from the second connection point 584q, tends to receive less fluid O. The third axial flow path 585c, which is located even further from the second connection point 584q, tends to receive even less fluid O.

[0146] According to this embodiment, the cross-sectional area of ​​the first axial flow path 585a, which is the configuration in which the most fluid O is most easily supplied, is the smallest. The cross-sectional area of ​​the second axial flow path 585b, which is the next most easily supplied with fluid O, is the second largest. Furthermore, the cross-sectional area of ​​the third axial flow path 585c, which is the configuration in which the least amount of fluid O is supplied, is the largest. Therefore, the flow rate of fluid O supplied to each of the axial flow paths 585a, 585b, and 585c can be made as uniform as possible.

[0147] Although various embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in each embodiment and its modifications are merely examples, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by its embodiments.

[0148] For example, the hole may penetrate the base portion in the axial direction. In this case, the hole does not have a female thread, and a nut is attached to the tip of the bolt 8 inserted into the hole 66.

[0149] The circumferential flow path does not have to be circular as long as it extends in the circumferential direction. For example, the circumferential flow path may be C-shaped when viewed from the axial direction.

[0150] The multiple plates constituting the stator core may include plates other than the first plate, second plate, third plate, and fourth plate.

[0151] Furthermore, the applications of the drive unit are not particularly limited. The drive unit may be mounted on equipment other than vehicles. The applications of the drive unit to which the present invention applies are not particularly limited. The drive unit may be mounted on a vehicle for purposes other than rotating an axle, for example, or on equipment other than vehicles. The orientation of the drive unit when it is used is not particularly limited. The central axis may be inclined with respect to the horizontal direction perpendicular to the vertical direction, or it may extend in the vertical direction.

[0152] Although embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments.

[0153] Furthermore, this technology can be configured as follows: [1] A motor comprising a rotor rotatable about a central axis and a stator surrounding the rotor from the radially outer side, wherein the stator comprises a stator core having a core internal flow path inside and a coil mounted on the stator core, the core internal flow path comprises a circumferential flow path extending along the circumferential direction and a plurality of axial flow paths extending along the axial direction, the stator core comprises a plurality of plates stacked in the axial direction, the plurality of axial flow paths are connected to the circumferential flow path and are arranged in the circumferential direction, at least a portion of the plurality of plates is provided with an opening that penetrates in the axial direction, and the opening is formed when the plurality of plates overlap in the axial direction [2] A drive device comprising, each constituting a part of the internal flow path of the core, wherein the plurality of plates include a first plate and a second plate adjacent to each other in the axial direction, the first plate is provided with a first opening extending in the circumferential direction as the opening, and the second plate is provided with a second opening extending in the circumferential direction and a part of which overlaps with the first opening in the axial direction, and the circumferential flow path comprises a first flow path portion provided inside the first opening, a second flow path portion provided inside the second opening, and a connecting flow path portion provided in the portion where one end of the first opening in the circumferential direction and the other end of the second opening in the circumferential direction overlap in the axial direction. [2] The drive device according to [1], wherein the internal flow path of the core comprises an inlet flow path located radially outside the circumferential flow path and connected to a flow path provided outside the stator core, and a connecting flow path extending radially and connecting the inlet flow path and the circumferential flow path. [3] The drive device according to [2], wherein the circumferential flow path has a plurality of first connecting portions arranged in a line in the circumferential direction and connected to the axial flow path, and a second connecting portion arranged between adjacent first connecting portions in the circumferential direction and connected to the connecting flow path. [4] The drive device according to [3], wherein the internal core flow path has a plurality of connecting flow paths branching off from one inlet flow path, the circumferential flow path has a plurality of second connecting portions to which different connecting flow paths are each connected, and the plurality of second connecting portions are each arranged between adjacent first connecting portions in the circumferential direction.[5] The drive device according to any one of [2] to [4], wherein the first plate body is provided with a third opening extending radially outward from the first opening as the opening, the connecting channel is provided inside the third opening, the first channel section has a second connecting section connected to the connecting channel, the connecting channel section is connected to a first end on one circumferential side and a second end on the other circumferential side of the first channel section, the first channel section extends downward from the second connecting section toward one circumferential side and extends upward from the second connecting section toward the other circumferential side, and in the first channel section, the path length from the second connecting section toward the first end is shorter than the path length from the second connecting section toward the second end. [6] The drive device according to [5], wherein the first end is located above the second end. [7] The drive device according to any one of [2] to [6], wherein the plurality of axial flow paths include a first axial flow path and a second axial flow path having a cross-sectional area greater than the cross-sectional area of ​​the first axial flow path, and the circumferential flow path has a second connecting portion connected to the connecting flow path, a third connecting portion connected to the first axial flow path, and a fourth connecting portion connected to the second axial flow path, and in the circumferential flow path, the path length from the second connecting portion to the third connecting portion is shorter than the path length from the second connecting portion to the fourth connecting portion. [8] The drive device according to any one of [2] to [7], wherein the stator core has a cylindrical portion surrounding the central axis and a plurality of protrusions projecting radially outward from the outer circumferential surface of the cylindrical portion, and the inlet flow path is provided in at least one of the plurality of protrusions. [9] The drive device according to [8], wherein the inlet flow path is provided in the protrusion located above the central axis among the plurality of protrusions.

[10] The drive device according to any one of [1] to [9], wherein the circumferential flow path comprises a plurality of first flow path sections arranged in the circumferential direction, a plurality of second flow path sections arranged in the circumferential direction with at least a portion of them offset from the first flow path sections in the circumferential direction, and a plurality of connecting flow path sections connecting the first flow path sections and the second flow path sections.

[11] The drive device according to any one of [1] to [9], wherein the circumferential flow path has one first flow path section, one second flow path section, and two connecting flow path sections, wherein one circumferential end of the first flow path section and the other circumferential end of the second flow path section are connected via the connecting flow path section, and the other circumferential end of the first flow path section and the one circumferential end of the second flow path section are connected via the connecting flow path section.

[12] The drive device according to any one of [1] to

[11] , wherein the axial flow path is located radially inward with respect to the circumferential flow path, and the core flow path has a radial flow path that extends radially and connects the circumferential flow path and the axial flow path.

[13] The drive device according to any one of [1] to

[12] , wherein the flow path cross-sectional area of ​​the connecting flow path section is 80% or more and 120% or less of the flow path cross-sectional area of ​​the first flow path section and the flow path cross-sectional area of ​​the second flow path section.

[14] The drive device according to any one of [1] to

[13] , wherein the circumferential flow path has a plurality of first connecting portions connected to the axial flow path, and the first connecting portions are provided at positions different from the connecting flow path portions in the circumferential direction.

[15] The drive device according to any one of [1] to

[14] , wherein the circumferential flow path is annular when viewed from the axial direction.

[16] The drive device according to any one of [1] to

[15] , wherein the axial flow paths are arranged at equal intervals in the circumferential direction.

[17] The drive device according to any one of [1] to

[16] , wherein the axial flow path extends linearly in the axial direction.

[0154] 2...Motor, 20...Rotor, 30...Stator, 31...Coil, 32...Stator core, 33...Core back section (cylindrical section), 35, 35A...Protruding section, 40...Plate, 41...First plate, 42...Second plate, 51...Opening, 51, 51A...First opening, 52...Second opening, 53...Third opening, 80, 180, 280, 380, 480, 580...Core internal flow path, 81...Inlet flow path, 82, 382, ​​482...Connecting flow path, 84, 184, 284, 484...Circumferential flow path, 84a, 184a, 284a...First flow path section, 84 b, 184b, 284b... Second flow path section, 84c, 184c, 284c... Connecting flow path section, 84p, 384p, 484p... First connection section, 85, 485, 585a... Axial flow path, 90... Flow path, 100... Drive unit, 184aa, 284aa... First end section, 184ab, 284ab... Second end section, 184q, 284q, 384q, 484q, 584q... Second connection section, 486... Radial flow path, 584r... Third connection section, 584t... Fourth connection section, 585a... First axial flow path, 585b... Second axial flow path, J... Central axis

Claims

1. A motor comprising a rotor rotatable about a central axis and a stator surrounding the rotor from the radially outer side, wherein the stator comprises a stator core having a core internal flow path inside, and coils mounted on the stator core, wherein the core internal flow path comprises a circumferential flow path extending along the circumferential direction and a plurality of axial flow paths extending along the axial direction, wherein the stator core comprises a plurality of plates stacked in the axial direction, wherein the plurality of axial flow paths are connected to the circumferential flow path and are arranged in the circumferential direction, wherein at least a portion of the plurality of plates is provided with an opening that penetrates in the axial direction, wherein the opening constitutes a part of the core internal flow path by the axial overlapping of the plurality of plates, wherein the plurality of plates include a first plate and a second plate adjacent to each other in the axial direction, wherein the first plate is provided with a first opening extending along the circumferential direction as the opening, and the second plate is provided with a second opening extending along the circumferential direction and a portion of which overlaps with the first opening in the axial direction, wherein the circumferential flow path is A drive device comprising: a first flow channel provided inside the first opening; a second flow channel provided inside the second opening; and a connecting flow channel provided in the portion where one circumferential end of the first opening and the other circumferential end of the second opening overlap in the axial direction.

2. The drive device according to claim 1, wherein the internal flow path of the core has an inlet flow path located radially outside the circumferential flow path and connected to a flow path provided outside the stator core, and a connecting flow path extending radially and connecting the inlet flow path and the circumferential flow path.

3. The drive device according to claim 2, wherein the circumferential flow path comprises a plurality of first connecting portions arranged in a circumferential direction and connected to the axial flow path, and a second connecting portion arranged between adjacent first connecting portions in the circumferential direction and connected to the connecting flow path.

4. The drive device according to claim 3, wherein the internal core flow path has a plurality of connecting flow paths branching off from one inlet flow path, the circumferential flow path has a plurality of second connection points to which different connecting flow paths are each connected, and the plurality of second connection points are each arranged between adjacent first connection points in the circumferential direction.

5. The drive device according to claim 2, wherein the first plate body is provided with a third opening extending radially outward from the first opening as an opening, the connecting channel is provided inside the third opening, the first channel section has a second connecting section connected to the connecting channel, the connecting channel section is connected to a first end on one circumferential side and a second end on the other circumferential side of the first channel section, the first channel section extends downward as it moves toward one circumferential side from the second connecting section and extends upward as it moves toward the other circumferential side from the second connecting section, and in the first channel section, the path length from the second connecting section to the first end is shorter than the path length from the second connecting section to the second end.

6. The drive device according to claim 5, wherein the first end is located above the second end.

7. The drive device according to claim 2, wherein the plurality of axial flow paths include a first axial flow path and a second axial flow path having a cross-sectional area greater than the cross-sectional area of ​​the first axial flow path, the circumferential flow path has a second connecting portion connected to the connecting flow path, a third connecting portion connected to the first axial flow path, and a fourth connecting portion connected to the second axial flow path, and in the circumferential flow path, the path length from the second connecting portion to the third connecting portion is shorter than the path length from the second connecting portion to the fourth connecting portion.

8. The drive device according to claim 2, wherein the stator core has a cylindrical portion surrounding the central axis and a plurality of protrusions projecting radially outward from the outer circumferential surface of the cylindrical portion, and the inlet passage is provided in at least one of the plurality of protrusions.

9. The drive device according to claim 8, wherein the inlet channel is provided on one of the multiple protrusions located above the central axis.

10. The drive device according to claim 1, wherein the circumferential flow path comprises a plurality of first flow path sections arranged in the circumferential direction, a plurality of second flow path sections arranged in the circumferential direction with at least a portion of them offset from the first flow path sections in the circumferential direction, and a plurality of connecting flow path sections connecting the first flow path sections and the second flow path sections.

11. The drive device according to claim 1, wherein the circumferential flow path comprises one first flow path section, one second flow path section, and two connecting flow path sections, wherein one circumferential end of the first flow path section and the other circumferential end of the second flow path section are connected via the connecting flow path sections, and the other circumferential end of the first flow path section and one circumferential end of the second flow path section are connected via the connecting flow path sections.

12. The drive device according to claim 1, wherein the axial flow path is located radially inward with respect to the circumferential flow path, and the core flow path has a radial flow path that extends radially and connects the circumferential flow path and the axial flow path.

13. The drive device according to claim 1, wherein the cross-sectional area of ​​the connecting channel is 80% or more and 120% or less of the cross-sectional area of ​​the first channel and the cross-sectional area of ​​the second channel.

14. The drive device according to claim 1, wherein the circumferential flow path has a plurality of first connecting portions connected to the axial flow path, and the first connecting portions are provided at positions different from the connecting flow path portions in the circumferential direction.

15. The drive device according to claim 1, wherein the circumferential flow path is annular when viewed from the axial direction.

16. The drive device according to claim 1, wherein the axial flow channels are arranged at equal intervals in the circumferential direction.

17. The drive device according to claim 1, wherein the axial flow path extends linearly in the axial direction.

Images