Rotor and rotating electric machine

Abstract

One aspect of a rotor according to the present invention can rotate about a central axis, and comprises: a shaft that extends along the central axis; a rotor core that is positioned radially outward with respect to the shaft; and a pair of end plates that are disposed on both sides in the axial direction of the rotor core and sandwich the rotor core in the axial direction. The end plates each have: a rib part that protrudes in the axial direction and extends in the circumferential direction; and a fin region that is positioned radially inward of the rib part and protrudes in the axial direction. A plurality of the fin regions are provided at intervals in the circumferential direction, and each of the fin regions has at least one fin extending in the circumferential direction.

Description

Rotor and Rotating Electric Machine

[0001] The present invention relates to a rotor and a rotating electric machine. This application claims priority based on Japanese Patent Application No. 2024-159925 filed in Japan on September 17, 2024, and incorporates the content herein by reference.

[0002] Rotating electric machines that cool the coil ends using a refrigerant are known. For example, in Patent Document 1, in a rotor, air holes are formed in a rotor core, blades are provided radially on an end plate, and the blades guide the air passing through the air holes and function as cooling fins to improve the cooling performance.

[0003] Japanese Unexamined Patent Application Publication No. 2014-158342

[0004] At the peripheral portion of the end plate, a rib portion that protrudes axially and extends circumferentially is provided as a balancer. When the assembled rotor has an imbalance, the balance of the rotor is corrected by cutting a part of the circumferential direction of the rib portion.

[0005] When the blades on the end plate are formed radially as cooling fins as in Patent Document 1, the air in contact with the cooling fins flows radially outward. Since the flow of the air toward the outside in the radial direction is blocked by the rib portion, there is a problem that the cooling performance deteriorates.

[0006] The present invention has been made in consideration of the above points, and an object thereof is to provide a rotor and a rotating electric machine capable of improving the cooling performance even when a rib portion is provided as a balancer.

[0007] One embodiment of the rotor of the present invention is a rotor rotatable about a central axis, comprising: a shaft extending along the central axis; a rotor core located radially outward from the shaft; and a pair of end plates arranged on both sides of the rotor core in the axial direction, sandwiching the rotor core in the axial direction, wherein each end plate has a rib portion protruding in the axial direction and extending circumferentially, and a fin region located radially inward from the rib portion and protruding in the axial direction, wherein a plurality of fin regions are provided spaced apart in the circumferential direction, and each fin region has at least one fin extending in the circumferential direction.

[0008] One embodiment of the rotating electric machine of the present invention comprises a rotor of one embodiment and a stator located radially outward of the rotor.

[0009] According to one aspect of the present invention, cooling performance can be improved even when ribs are provided as balancers.

[0010] Figure 1 is a schematic cross-sectional view of a rotating electric machine according to one embodiment. Figure 2 is a view of the end plate from the +Y side in the axial direction. Figure 3 is a cross-sectional view taken along line A-A in Figure 2. Figure 4 is a view of a modified end plate from the +Y side in the axial direction. Figure 5 is a schematic cross-sectional view of a modified rotating electric machine.

[0011] The rotor and rotating electric machine according to embodiments of the present invention will be described below with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and modifications can be made as appropriate within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand.

[0012] In the following description, the vertical direction will be defined and explained based on the positional relationship when the rotating electric machine of the embodiment is mounted on a vehicle located on a horizontal road surface. In other words, the relative positional relationship with respect to the vertical direction described in the following embodiment only needs to be satisfied when the rotating electric machine is mounted on a vehicle located on a horizontal road surface.

[0013] In the drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. In the XYZ coordinate system, the Z-axis direction is the vertical direction. The +Z side is the upper vertical side, and the -Z side is the lower vertical side. In the following description, the upper vertical side will simply be referred to as the "upper side," and the lower vertical side will simply be referred to as the "lower side." The X-axis direction is perpendicular to the Z-axis direction and is the longitudinal direction of the vehicle on which the drive unit is mounted. In the following embodiments, the +X side is the front of the vehicle, and the -X side is the rear of the vehicle. The Y-axis direction is perpendicular to both the X-axis and Z-axis directions and is the lateral direction of the vehicle, i.e., the vehicle width direction. In the following embodiments, the +Y side is the left side of the vehicle, and the -Y side is the right side of the vehicle. The longitudinal and lateral directions are horizontal directions perpendicular to the vertical direction.

[0014] Furthermore, the relative positions in the front-rear direction are not limited to those of the embodiments described below; the +X side may be the rear of the vehicle and the -X side may be the front of the vehicle. In this case, the +Y side is the right side of the vehicle and the -Y side is the left side of the vehicle. Also, in this specification, "parallel directions" include substantially parallel directions, and "orthogonal directions" also include substantially orthogonal directions.

[0015] The central axis J, as shown in the diagrams, is a virtual axis extending in a direction intersecting the vertical direction. More specifically, the central axis J extends in the Y-axis direction perpendicular to the vertical direction, that is, in the left-right direction of the vehicle. In the following explanation, unless otherwise specified, the direction parallel to the central axis J will be simply called the "axial direction," the radial direction centered on the central axis J will be simply called the "radial direction," and the circumferential direction centered on the central axis J, that is, around the axis of the central axis J, will be simply called the "circumferential direction."

[0016] In one embodiment, the rotating electric machine 10 is a motor. The motor is, for example, a drive device mounted on a vehicle that rotates the vehicle's axle.

[0017] The rotating electric machine 10 comprises a motor housing 20, a rotor 30 that can rotate about a central axis J, and a stator 40 that is located radially outside the rotor 30 and faces the rotor 30 with a radial gap between them. The motor housing 20 is a housing that houses the rotor 30 and the stator 40 inside.

[0018] The stator 40 is located radially outward from the rotor 30. The stator 40 is fixed inside the motor housing 20. The stator 40 is annular in shape with a central axis J. The stator 40 includes a stator core 41 and a coil assembly 42.

[0019] The stator core 41 is an annular shape that surrounds the central axis J of the rotating electric machine 10. The stator core 41 is located radially outward from the rotor 30. The stator core 41 surrounds the rotor 30. The stator core 41 is constructed by stacking multiple plate members, such as electrical steel sheets, in the axial direction. Although not shown in the figures, the stator core 41 has a cylindrical core back extending in the axial direction and a plurality of teeth extending radially inward from the core back. The plurality of teeth are arranged at equal intervals along the circumferential direction over a full circumference.

[0020] The coil assembly 42 has a plurality of coils 42c attached to the stator core 41. Each coil 42c is made of, for example, a flat wire with a square or substantially square cross-section. Alternatively, each coil 42c may be made of, for example, a round wire with a circular cross-section. The plurality of coils 42c are each mounted on the stator core 41 via insulators 43. The insulators 43 are, for example, positioned between the teeth of the stator core 41 in the circumferential direction. The insulators 43 are, for example, insulating paper. The insulators 43 protrude from the stator core 41 on both axial sides. Although not shown in the figures, the coil assembly 42 may have binding members for bundling the coils 42c together, or it may have connecting wires for connecting the coils 42c together.

[0021] The coil assembly 42 has coil ends 42a and 42b that protrude axially beyond the stator core 41. Coil end 42a is the portion that protrudes to the right of the stator core 41. Coil end 42b is the portion that protrudes to the left of the stator core 41. Coil end 42a includes the portion of each coil 42c included in the coil assembly 42 that protrudes to the right of the stator core 41. Coil end 42b includes the portion of each coil 42c included in the coil assembly 42 that protrudes to the left of the stator core 41.

[0022] In this embodiment, the coil ends 42a and 42b are annular in shape with respect to the central axis J. Although not shown in the figures, the coil ends 42a and 42b may include binding members for bundling the coils 42c together, or they may include connecting wires for connecting the coils 42c together. The right end of coil end 42a is located to the right of the right end of insulator 43. The left end of coil end 42b is located to the left of the left end of insulator 43.

[0023] The rotor 30 is positioned radially inward of the stator 40. The rotor 30 comprises a shaft 31, a rotor core 32, a magnet 33, and an end plate 50. The shaft 31 extends along the central axis J. In this embodiment, the shaft 31 is a cylindrical shaft extending axially about the central axis J. At the left end of the shaft 31, a recess 31c is provided along the central axis J and is open, into which a second shaft (not shown) is fitted. The shaft 31 is rotatable about the central axis J. The shaft 31 is rotatably supported by bearings 24 and 25 supported by the motor housing 20.

[0024] The shaft 31 is provided with a flange portion 31a that protrudes radially outward from the outer circumferential surface of the shaft 31. In other words, the rotor 30 has a flange portion 31a as a projection that protrudes radially outward from the outer circumferential surface of the shaft 31. The flange portion 31a is provided on the outer circumferential surface of the portion of the shaft 31 located to the left of the rotor core 32. The flange portion 31a and the shaft 31 are part of the same single component. The flange portion 31a is an annular shape that surrounds the shaft 31 with the central axis J as its center. The flange portion 31a is located radially inward from the coil end 42b. The left end of the flange portion 31a is located to the right of the left end of the coil end 42b. The flange portion 31a sandwiches the end plate 50b, which will be described later, between itself and the rotor core 32 in the axial direction.

[0025] A nut 36 is attached to the shaft 31. The nut 36 is fastened to a threaded portion 31b provided on the outer circumferential surface of the shaft 31. The nut 36 is located to the right of the end plate 50a, which will be described later. The nut 36 is an annular shape that surrounds the shaft 31 in the circumferential direction, with the central axis J as its center. The inner circumferential surface of the nut 36 is provided with a threaded portion that engages with the threaded portion 31b of the shaft 31. The maximum outer diameter of the nut 36 is larger than the maximum outer diameter of the flange portion 31a. The nut 36 is located radially inward of the coil end 42a. The nut 36 sandwiches the end plate 50a, which will be described later, between itself and the rotor core 32 in the axial direction.

[0026] The rotor core 32 is fixed to the shaft 31. The rotor core 32 is cylindrical in shape, enclosing the shaft 31 and extending in the axial direction. The inner circumferential surface of the rotor core 32 is fixed to the outer circumferential surface of the shaft 31. The rotor core 32 is constructed by stacking multiple plate members, such as electromagnetic steel sheets, in the axial direction. The rotor core 32 has a magnet hole 32a and a through hole 34.

[0027] The magnet holes 32a penetrate the radially outer portion of the rotor core 32 in the axial direction. Multiple magnet holes 32a are provided at intervals in the circumferential direction. In this embodiment, the through holes 34 penetrate the radially inner portion of the magnet holes 32a in the axial direction.

[0028] Multiple through holes 34 are provided at intervals in the circumferential direction. In this embodiment, six through holes 34 are provided at 60° intervals in the circumferential direction. As an example, the through holes 34 have a shape that is convex radially outward when viewed from the axial direction. More specifically, the through holes 34 in this embodiment have an oval shape that extends radially when viewed from the axial direction, and the radius of the arc located on the radially outward side is smaller than the radius of the arc located on the radially inward side.

[0029] The magnets 33 are fixed to the rotor core 32. Multiple magnets 33 are provided. Each of the multiple magnets 33 is inserted into a multiple magnet hole 32a. Each of the multiple magnets 33 extends in the axial direction. The axial dimension of the magnets 33 is approximately the same as the axial dimension of the rotor core 32.

[0030] The rotor 30 includes end plates 50 arranged axially alongside the rotor core 32. The rotor 30 in this embodiment includes two end plates 50: an end plate 50a located to the right of the rotor core 32 and an end plate 50b located to the left of the rotor core 32.

[0031] The two end plates 50a and 50b are positioned to sandwich the rotor core 32 in the axial direction. The two end plates 50a and 50b are fixed to the rotor core 32 by being sandwiched between the nut 36 and the flange portion 31a when the nut 36 is fastened to the shaft 31. In this way, the provision of the nut 36 and the flange portion 31a prevents the end plates 50a and 50b from shifting in the axial direction relative to the rotor core 32.

[0032] Each end plate 50a and 50b closes the axial ends of the magnet hole 32a. As a result, the magnet 33 is held in place from both axial sides by each end plate 50a and 50b, preventing the magnet 33 from protruding axially from the magnet hole 32a. The end plates 50a and 50b are mainly similar in configuration, except that they are arranged symmetrically in the axial direction with respect to the rotor core 32. Therefore, in the following explanation, only the end plate 50b may be described as a representative example.

[0033] Figure 2 shows the end plate 50b of this embodiment as viewed axially from the +Y side. Figure 3 is a cross-sectional view taken along line A-A in Figure 2. Figure 1 is a cross-sectional view taken at the position corresponding to line B-B in Figure 2.

[0034] As shown in Figure 2, the end plate 50b has a main body portion 50c, a rib portion 51, a fin region 52, a hole portion 53, a recess 54, and an insertion hole 50h. The shaft 31 is inserted into the insertion hole 50h.

[0035] The main body portion 50c is an annular plate-shaped member with its plate surface facing axially around the central axis J. The rib portion 51 is provided near the outer edge of the main body portion 50c and protrudes axially away from the rotor core 32. The rib portion 51 extends in the circumferential direction. The rib portion 51 can be used, for example, as a cutting allowance for balancing the rotor 30. That is, if the rotor 30 is unbalanced after assembly, the balance of the rotor 30 can be corrected by cutting a part of the circumferential direction of the rib portion 51. In other words, the rib portion 51 functions as a balancer. As for the cutting method of the rib portion 51, for example, one method is to drill the radially outward-facing surface of the rib portion 51, but it is not particularly limited to this method.

[0036] The fin region 52 is located radially inward from the rib portion 51. The fin region 52 has at least one fin F extending in the circumferential direction. The fin region 52 has two or more fins F arranged radially via grooves 55. Each fin F extends circumferentially in an arc shape centered on the central axis J. Each fin F may be configured to incline radially inward or radially outward as it moves toward one side in the circumferential direction.

[0037] As shown in Figure 3, in this embodiment, the fin region 52 has eight fins F arranged radially via grooves 55. Multiple fin regions 52 are provided at intervals in the circumferential direction. In this embodiment, three fin regions 52 are provided at intervals in the circumferential direction.

[0038] When the rotor 30 rotates, the centrifugal force causes the air to move radially outward. However, because the rib portion 51 is provided near the outer edge of the main body portion 50c, the radial airflow is obstructed. Therefore, if the fins F extend radially, the air does not flow effectively. In contrast, in this embodiment, since the fins F extend circumferentially, as the rotor 30 rotates, the fins F move relative to the air, increasing the heat exchange area between the fins F and the air, thereby improving the efficiency of heat exchange.

[0039] Furthermore, since multiple fin regions 52 are provided at intervals in the circumferential direction, the grooves 55 between the fins F open at both ends in the circumferential direction. As a result, as the rotor 30 rotates, air can flow in from the opening at one end of the groove 55 in the circumferential direction and flow out from the opening at the other end, thereby further improving the efficiency of heat exchange.

[0040] Of the multiple fins F, the fin F positioned furthest in the radial direction may come into contact with the nut 36 when fastening the nut 36 to the threaded portion 31b of the shaft 31. Therefore, by increasing the radial dimension W of the fin F positioned furthest in the radial direction, its strength is increased, and damage can be suppressed even if it comes into contact with the nut 36.

[0041] On the other hand, among the plurality of fins F, the fin F arranged on the outermost side in the radial direction is subjected to the maximum value of centrifugal force accompanying the rotation of the rotor 30. Therefore, by making the radial dimension of the fin F arranged on the outermost side in the radial direction the largest, the resistance to the large centrifugal force can be improved. From the viewpoint of improving the resistance to centrifugal force, the plurality of fins F may be configured such that the radial dimension increases toward the outside in the radial direction.

[0042] Therefore, depending on the specifications of the rotating electric machine 10, when emphasis is placed on the strength at the time of contact with the nut 36 rather than the resistance to centrifugal force, the radial dimension of the fin F arranged on the innermost side in the radial direction may be made the largest. Also, when emphasis is placed on the resistance to centrifugal force rather than the strength at the time of contact with the nut 36, the radial dimension of the fin F arranged on the outermost side in the radial direction may be made the largest. Further, when both the resistance to centrifugal force and the strength at the time of contact with the nut 36 are to be achieved, the radial dimensions of both fins F located at both ends in the radial direction may be made the largest and the same.

[0043] The hole portion 53 is provided between the fin regions 52. The radial size of the hole portion 53 is such that the plurality of fins F overlap in the circumferential direction. Thereby, the air that has flowed through the groove portion 55 and has been heat-exchanged by the fins F can smoothly pass through the hole portion 53.

[0044] The hole portion 53 is arranged farther away from the nut 36 in the radial direction. Since the hole portion 53 is arranged farther away from the nut 36 in the radial direction, it is possible to easily allow air to flow into the through hole 34 inside the rotor core 32 through the hole portion 53 without being obstructed by the nut 36.

[0045] The hole portions 53 are arranged in three at 120° intervals in the circumferential direction between the fin regions 52. As shown in FIG. 1, the hole portions 53 penetrate the main body portion 50c in the axial direction. The hole portions 53 are, as an example, convex toward the outside in the radial direction when viewed from the axial direction. More specifically, the hole portions 53 of the present embodiment are substantially triangular in shape with rounded corners that are convex toward the outside in the radial direction when viewed from the axial direction. The shape of the hole portions 53 is not limited to the present embodiment. The shape of the hole portions 53 may be, for example, circular, elliptical, polygonal, or a shape in which at least a part protrudes in the circumferential direction or the radial direction when viewed from the axial direction.

[0046] Each of the hole portions 53 overlaps at least a part of one of the plurality of through holes 34 in the axial direction. Each of the hole portions 53 is connected to one of the plurality of through holes 34. The hole portions 53 of the present embodiment are provided in a range where all of one of the through holes 34 overlap when viewed from the axial direction. Thereby, air can flow between the hole portions 53 and one of the plurality of through holes 34.

[0047] As shown in FIG. 3, the recessed portions 54 are provided on the back side of the fin regions 52 in the axial direction in the main body portion 50c. The recessed portions 54 are provided on the surface of the main body portion 50c facing the rotor core 32. The recessed portions 54 are recessed from the surface of the main body portion 50c facing the rotor core 32. The recessed portions 54 are arranged in three at 120° intervals in the circumferential direction. The recessed portions 54 are arranged at 60° intervals from the hole portions 53 in the circumferential direction. That is, the hole portions 53 and the recessed portions 54 are alternately arranged at 60° intervals in the circumferential direction.

[0048] The recessed portions 54 have a first portion 54A and a second portion 54B. The radial position of the first portion 54A is substantially the same as the radial position of the hole portions 53. When viewed from the axial direction, the first portion 54A is trapezoidal in shape with the outside in the radial direction tapering more than the inside in the radial direction. When viewed from the axial direction, the second portion 54B is rectangular in shape extending radially outward from the radially outer end of the first portion 54A. The second portion 54B opens to the outer peripheral surface of the main body portion 50c. When viewed from the axial direction, the recessed portions 54 are in a flask shape in which the circumferential width gradually narrows from the inside in the radial direction toward the outside in the radial direction and then extends to the radially outer end with a constant circumferential width.

[0049] Since the second portion 54B opens to the outer circumferential surface of the main body portion 50c, the recess 54 functions as an air outlet that blows air radially outward, and can also blow air onto the coil ends 42a and 42b located radially outward to cool them.

[0050] The first portion 54A overlaps, at least partially, in the axial direction with a through-hole 34 that is different from the through-hole 34 that overlaps with the hole portion 53 in the axial direction. In this embodiment, the first portion 54A is provided in a range where all of one of the through-holes 34 overlap when viewed from the axial direction. This allows air to flow between the first portion 54A and one of the multiple through-holes 34.

[0051] The end plate 50b in the above configuration has the same configuration as the end plate 50a, but as shown in Figure 1, the hole 53 of the end plate 50b and the recess 54 of the end plate 50a face each other in the axial direction, and the recess 54 of the end plate 50b and the hole 53 of the end plate 50a overlap in the axial direction. That is, three of the six through holes 34 connect the hole 53 of the end plate 50b to the recess 54 of the end plate 50a. The other three of the six through holes 34 connect the recess 54 of the end plate 50b to the hole 53 of the end plate 50a.

[0052] In the rotating electric machine 10 with the above configuration, when the rotor 30 rotates, centrifugal force is applied to the air inside the recess 54 due to rotation around the central axis J. As a result, the air inside the recess 54 is blown radially outward. The blowing of air from the recess 54 creates negative pressure inside the through hole 34 connected to the recess 54. As a result, air flows into the through hole 34 through the opening 53. An axial airflow is formed in the through hole 34 from the opening 53 toward the recess 54. The air in adjacent through holes 34 in the circumferential direction flows in opposite axial directions relative to each other.

[0053] According to this embodiment, even if the radial airflow is obstructed by the rib portion 51 provided near the outer edge of the main body portion 50c, the fins F extend in the circumferential direction. As the rotor 30 rotates, the fins F move relative to the air, increasing the heat exchange area between the fins F and the air, thereby improving the efficiency of heat exchange and enhancing cooling performance.

[0054] Furthermore, according to this embodiment, the air in adjacent through holes 34 in the circumferential direction flows in opposite directions relative to each other in the axial direction. As a result, the reaction forces of air resistance applied to the inner surfaces of adjacent through holes 34 in the circumferential direction cancel each other out in the rotor 30. According to this embodiment, it is possible to suppress the application of uneven forces to the rotor 30 due to the reaction forces of air resistance, and thus suppress the deterioration of the rotational balance of the rotor 30.

[0055] Furthermore, according to this embodiment, since multiple fin regions 52 are provided spaced apart in the circumferential direction, as the rotor 30 rotates, air can flow in from the opening on one end of the groove 55 in the circumferential direction and flow out from the opening on the other end, thereby further improving the efficiency of heat exchange.

[0056] Furthermore, according to this embodiment, among the multiple fins F, the fin F with the largest radial dimension W is positioned at least on the innermost radial side. As a result, the strength of the fin F located on the innermost radial side is increased, and damage can be suppressed even if it comes into contact with the nut 36.

[0057] Furthermore, according to this embodiment, since the hole 53 is positioned radially outward from the nut 36, air can be easily allowed to flow into the through hole 34 inside the rotor core 32 through the hole 53 without being obstructed by the nut 36.

[0058] [Examples] The effects of the present invention will be made clearer by the following examples. However, the present invention is not limited to the following examples and can be modified as appropriate without changing its essence.

[0059] (Examples 1-2, Comparative Example 1) In this example, end plates for Examples 1-2 and Comparative Example 1 were manufactured as samples according to the specifications shown in Table 1 below. The sample for Example 1 was the end plate shown in Figures 2-3. The sample for Example 2 had 5 fins, compared to the sample for Example 1 which had 8 fins. The sample for Comparative Example 1 was a sample without a fin area.

[0060] [Measurement Items] Thermal fluid analysis was performed using each sample of the end plate, and the temperature of the coil and magnet were measured. As the analysis solver, Siemens Corporation's "Simcenter STAR-CCM+ 2022.1" was used, and the turbulence model was the "k-ε model" with gravity taken into consideration. The main physical properties used in the calculation are as follows for the fluid: Type: Air (120℃). Molecular weight: 28.9664 kg / mol. Specific heat: 1014 J / kgK. Thermal conductivity: 0.0331 W / mK. Set rotation speed: 18550 rpm. The main physical properties used in the calculation are as follows for the end plate: Type: Aluminum (Al). Density: 2702 kg / m³ ３ Specific heat: 903 J / kgK. Thermal conductivity: 150 W / mK.

[0061]

[0062] As shown in Table 1, in the samples of Examples 1 and 2, which have fins in the fin region, the coil temperature and magnet temperature were lower than in Comparative Example 1, which was a sample without fins, confirming that cooling performance can be improved.

[0063] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

[0064] ​For example, in the above embodiment, a configuration was illustrated in which holes 53 are provided at all locations where the fin regions 52 are spaced apart in the circumferential direction, but the configuration is not limited to this. For example, as shown in the modified example in Figure 4, the configuration may include intervals S between the fin regions 52 where no holes 53 are provided.

[0065] Furthermore, although the above embodiment illustrates a configuration in which the rotor core 32 has a through hole 34 and the end plate 50 has a hole portion 53, the configuration is not limited to this. For example, in the case of a rotating electric machine used in a drone or the like, the rotor core is thin, so the through hole 34 and hole portion 53 may not be provided.

[0066] Furthermore, although the above embodiment illustrates a configuration in which the shape of the through hole 34 and the shape of the hole portion 53 as viewed in the axial direction are different, the configuration is not limited to this. For example, the shape of the through hole 34 and the shape of the hole portion 53 as viewed in the axial direction may be the same. By making the shape of the through hole 34 and the shape of the hole portion 53 as viewed in the axial direction the same, it becomes possible to allow smooth flow into the interior of the rotor core 32.

[0067] Furthermore, the rotor core 32 described in the above embodiment may have a configuration having a plurality of core pieces arranged in the axial direction. Figure 5 is a schematic cross-sectional view of a modified rotating electric machine 10. As shown in Figure 5, the rotor core 32 has a plurality of core pieces 32p arranged in the axial direction. Each of the plurality of core pieces 32p is constructed by stacking a plurality of plate members in the axial direction. Core pieces 32p adjacent to each other in the axial direction are in contact with each other. Note that a separate plate-shaped member may be sandwiched between axially adjacent core pieces 32p. In the example of Figure 5, six core pieces 32p are provided. Although not shown, the plurality of core pieces 32p are arranged with their circumferential positions offset from each other. In other words, in this embodiment, a step skew is provided on the rotor 30.

[0068] The through holes 34 are provided to penetrate each core piece 32p in the axial direction. In Figure 5, for convenience, some of the through holes 34 in each core piece 32p are offset radially, but in reality they are offset circumferentially. The through holes 34 in axially opposing core pieces 32p overlap in the axial direction at least in part. The axially opposing core pieces 32p and the hole 53 overlap in the axial direction at least in part. The axially opposing core pieces 32p and the recess 54 overlap in the axial direction at least in part.

[0069] Therefore, the present invention can also be applied to rotors 30 and rotating electric machines 10 that are provided with a step skew.

[0070] Furthermore, this technology can take the following configurations: (1) A rotor rotatable about a central axis, comprising: a shaft extending along the central axis; a rotor core located radially outward from the shaft; and a pair of end plates arranged on both sides of the rotor core in the axial direction, sandwiching the rotor core in the axial direction, wherein the end plates have rib portions protruding in the axial direction and extending in the circumferential direction, and fin regions located radially inward from the rib portions and protruding in the axial direction, wherein a plurality of fin regions are provided spaced apart in the circumferential direction, and each fin region has at least one fin extending in the circumferential direction. (2) The rotor according to (1), wherein the rotor core has a plurality of through holes opening at the axial end, and the end plates have holes between the fin regions, and one of the plurality of through holes and the hole overlap in the axial direction at least in part. (3) The rotor according to (2), wherein the end plate has a recess on the back side of the fin region in the axial direction, and the recess has a first portion that overlaps in the axial direction with at least a portion of the through holes, which is different from the through holes that overlap with the hole portion in the axial direction, and a second portion that extends radially outward from the first portion and opens. (4) The rotor according to (2) or (3), wherein the shaft has a flange portion that is located on one side in the axial direction from one of the end plates and protrudes radially outward, a threaded portion that is located on the other side in the axial direction from the other end plate and is provided on the outer circumferential surface, and a nut that is fastened to the threaded portion, and the pair of end plates and the rotor core are sandwiched between the nut fastened to the threaded portion and the flange portion, and the hole portion is located radially outward from the nut. (5) The rotor according to any one of (1) to (4), wherein two or more fins are arranged radially in the fin region via grooves. (6) The rotor according to (5), wherein of the two or more fins, the fin with the largest radial dimension is positioned at least on the innermost radial side.(7) The rotor according to any one of (2) to (4), wherein the spacing between the fin regions includes the spacing in which the holes are not located. (8) A rotating electric machine comprising the rotor according to any one of (1) to (7) and a stator located radially outward of the rotor.

[0071] 10... Rotating electric machine, 30... Rotor, 31... Shaft, 31a... Flange section, 31b... Screw section, 32... Rotor core, 34... Through hole, 36... Nut, 40... Stator, 50, 50a, 50b... End plate, 51... Rib section, 52... Fin area, 53... Hole section, 54... Recess, 54A... First section, 54B... Second section, 55... Groove section, F... Fin, J... Central axis

Claims

1. A rotor rotatable about a central axis, comprising: a shaft extending along the central axis; a rotor core located radially outward from the shaft; and a pair of end plates positioned on both sides of the rotor core in the axial direction, sandwiching the rotor core in the axial direction, wherein each end plate has: a rib portion projecting in the axial direction and extending circumferentially; and a fin region located radially inward from the rib portion and projecting in the axial direction, wherein a plurality of fin regions are provided spaced apart in the circumferential direction, and each fin region has at least one fin extending in the circumferential direction.

2. The rotor according to claim 1, wherein the rotor core has a plurality of through holes opening at the axial end, the end plate has holes between the fin regions, and one of the plurality of through holes and the hole overlap at least in part in the axial direction.

3. The rotor according to claim 2, wherein the end plate has a recess on the back side of the fin region in the axial direction, and the recess has a first portion that overlaps in the axial direction with at least a portion of the through holes, which are different from the through holes that overlap with the hole portion in the axial direction, and a second portion that extends radially outward from the first portion and opens.

4. The rotor according to claim 2, wherein the shaft has a flange portion located on one side in the axial direction of one of the end plates and projecting radially outward, a threaded portion located on the outer circumferential surface of the shaft located on the other side in the axial direction of the other end plate, and a nut fastened to the threaded portion, the pair of end plates and the rotor core being sandwiched between the nut fastened to the threaded portion and the flange portion, and the hole portion being positioned radially outward from the nut.

5. The rotor according to claim 1, wherein two or more fins are arranged radially in the fin region via grooves.

6. The rotor according to claim 5, wherein of the two or more fins, the fin with the largest radial dimension is positioned at least furthest inward in the radial direction.

7. The rotor according to claim 2, wherein the spacing between the fin regions includes the spacing where the holes are not located.

8. A rotating electric machine comprising: a rotor according to any one of claims 1 to 7; and a stator located radially outward of the rotor.

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