Rotor of electric motor and manufacturing method thereof

Abstract

To provide a novel and useful technique for fixing end plates.SOLUTION: A rotor of an electric motor includes a shaft extending in an axial direction, a rotor core fixed to the outer peripheral surface of the shaft, and a first end plate fixed to the outer peripheral surface of the shaft and abutting on axial one end side of the rotor core. The outer peripheral surface of the shaft has a first outer peripheral surface abutting on an inner peripheral surface of the rotor core, a second outer peripheral surface located on axial one side with respect to the first outer peripheral surface and having a larger diameter than the first outer peripheral surface; and a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and abutting on the inner peripheral surface of the first end plate. The first inclined surface has a larger diameter from the first outer peripheral surface to the second outer peripheral surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a rotor for an electric motor and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 discloses a rotor for an electric motor. This rotor includes a shaft extending in the axial direction, a rotor core fixed to the outer peripheral surface of the shaft, an end plate fixed to the outer peripheral surface of the shaft and abutting against one axial end face of the rotor core, and a rotation prevention member fixed to the outer peripheral surface of the shaft and abutting against one axial end face of the end plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-109804 Summary of the Invention [Problem to be solved by the invention]

[0004] In the rotor of Patent Document 1, the anti-rotation member abuts against one axial end face of the end plate, generating friction between the anti-rotation member and the end plate. This friction force secures the end plate to the shaft and rotor core. There is a need for technology that can simplify the structure for securing the end plate to the shaft and rotor core.

[0005] This specification provides a technique that can simplify the structure for fixing the end plates to the shaft and rotor core. [Means for solving the problem]

[0006] In a first aspect of the present technology, a rotor of an electric motor may include a shaft extending in an axial direction, a rotor core fixed to an outer peripheral surface of the shaft, and a first end plate fixed to the outer peripheral surface of the shaft and abutting an end surface on one axial side of the rotor core. The outer peripheral surface of the shaft may have a first outer peripheral surface abutting an inner circumferential surface of the rotor core, a second outer peripheral surface located on one axial side of the first outer peripheral surface and having a larger diameter than the first outer peripheral surface, and a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and abutting an inner circumferential surface of the first end plate. The diameter of the first inclined surface may increase from the first outer peripheral surface toward the second outer peripheral surface.

[0007] With the above configuration, the first end plate is subjected to not only a radial restoring force (reaction force) from the first inclined surface of the shaft, but also an axial restoring force toward the rotor core (i.e., the other axial side). This allows the first end plate to firmly hold the rotor core from one axial side. In this way, the first inclined surface of the shaft can be used to fix the end plate to the shaft and rotor core. This simplifies the structure for fixing the end plate to the shaft and rotor core.

[0008] In a second aspect, in the first aspect, the shaft may be elastically deformed radially inward at least at the first inclined surface, and a restoring force resulting from the elastic deformation may act on the first end plate. In other words, the first end plate may be interference-fitted onto the shaft.

[0009] With the above configuration, it is possible to increase the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force resulting from the restoring force. Note that, although this is merely an example, the above configuration can be realized by shrink fitting, cold fitting, press fitting, or the like.

[0010] In a third aspect, in the second aspect, the first end plate may be elastically deformed radially outward at least at its inner surface that abuts the first inclined surface, and the amount of elastic deformation of the first end plate may increase as it moves away from the rotor core.

[0011] With the above configuration, the restoring force of the first end plate on the other axial side is greater than the restoring force on the one axial side, and therefore the first end plate can firmly hold the rotor core from the one axial side.

[0012] In a fourth aspect, in any one of the first to third aspects, the diameter of the outer peripheral surface of the first end plate may be larger than the diameter of the outer peripheral surface of the rotor core or may be equal to the diameter of the outer peripheral surface of the rotor core.

[0013] According to the above configuration, the first end plate can firmly hold the rotor core from one axial side up to the radially outer end thereof.

[0014] In a fifth aspect, in any one of the first to fourth aspects, an edge on the one axial side of the inner peripheral surface of the first end plate may be located on the first inclined surface of the shaft, where "on the first inclined surface" includes the boundary between the first inclined surface and the second outer peripheral surface.

[0015] With the above configuration, the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force resulting from this restoring force can be increased compared to a configuration in which the edge on one axial side of the inner peripheral surface of the first end plate extends beyond the first inclined surface of the shaft and is positioned on the second outer peripheral surface.

[0016] In a sixth aspect, in the fifth aspect, the edge on one axial side of the inner circumferential surface of the first end plate may be located on the boundary between the second outer circumferential surface of the shaft and the first inclined surface.

[0017] With this configuration, the area where the inner circumferential surface of the first end plate comes into contact with the first inclined surface of the shaft can be increased, thereby increasing the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force resulting from this restoring force.

[0018] In a seventh aspect, in the sixth aspect, the dimension of the inner circumferential surface of the first end plate in the axial direction may be equal to the dimension of the first inclined surface of the shaft in the axial direction.

[0019] According to the above configuration, the area of contact between the inner peripheral surface of the first end plate and the first inclined surface of the shaft can be maximized.

[0020] In an eighth aspect, in any one of the first to seventh aspects, the rotor may further include a second end plate fixed to the outer peripheral surface of the shaft and abutting an end surface on the other axial side of the rotor core. The outer peripheral surface of the shaft may have a third outer peripheral surface located on the other axial side of the first outer peripheral surface and having a larger diameter than the first outer peripheral surface, and a second inclined surface located between the first outer peripheral surface and the third outer peripheral surface in the axial direction and abutting an inner peripheral surface of the first end plate. The diameter of the second inclined surface may increase from the first outer peripheral surface toward the third outer peripheral surface.

[0021] With the above configuration, the second end plate is subjected to not only a radial restoring force (reaction force) from the second inclined surface of the shaft, but also an axial restoring force (i.e., one axial side) toward the rotor core. This allows the second end plate to firmly hold the rotor core from the other axial side. In other words, the rotor core is firmly held from both axial sides by both the first end plate and the second end plate.

[0022] A ninth aspect of the present technology discloses a method for manufacturing a rotor for an electric motor. The rotor may include a shaft extending in an axial direction, a rotor core fixed to an outer peripheral surface of the shaft, and a first end plate fixed to the outer peripheral surface of the shaft and abutting an end surface on one axial side of the rotor core. The outer peripheral surface of the shaft may have a first outer peripheral surface, a second outer peripheral surface located on one axial side of the first outer peripheral surface and having a larger diameter than the first outer peripheral surface, and a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and having a diameter increasing from the first outer peripheral surface to the second outer peripheral surface. The manufacturing method may include the steps of temporarily expanding an inner peripheral surface of the rotor core radially outward to fix the rotor core to the first outer peripheral surface of the shaft, and temporarily expanding an inner peripheral surface of the first end plate radially outward to fix the first end plate to the first inclined surface of the shaft.

[0023] With the above configuration, the first end plate can be tightly fitted onto the shaft. This increases the restoring force (reaction force) acting on the first end plate from the first inclined surface of the shaft and the frictional force resulting from this restoring force. In particular, the first end plate is subjected to not only a radial restoring force from the first inclined surface of the shaft, but also an axial restoring force acting toward the rotor core (i.e., the other axial side). Therefore, the first end plate can firmly hold the rotor core from one axial side.

[0024] In a tenth aspect, in the ninth aspect, the step of fixing the first end plate may be performed after the step of fixing the rotor core.

[0025] According to the above configuration, various parameters can be appropriately set in each of the steps of fixing the first end plate and fixing the rotor core. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a cross-sectional view of the rotor 2. [Figure 2] FIG. 2 is an enlarged view of a portion of the rotor 2 in FIG. [Figure 3] 10 is a diagram showing a step of attaching the rotor 2 to the shaft 10 in the method of manufacturing the rotor 2. FIG. [Figure 4] 10 is a diagram showing a step of attaching the left end plate 14 and the right end plate 16 to the shaft 10 in the manufacturing method of the rotor 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] (Example) The rotor 2 will be described with reference to Figures 1 and 2. The rotor 2 is a rotor of an electric motor mounted on an electric vehicle or the like. Note that the up-down and left-right directions in each figure are added for ease of understanding and do not define actual directions.

[0028] As shown in FIG. 1, the rotor 2 includes a shaft 10 extending in the direction of axis A, a rotor core 12, a left end plate 14, and a right end plate 16. The direction of axis A is parallel to the left-right direction. As shown in FIG. 2, the shaft 10 includes an outer peripheral surface 20 including a first outer peripheral surface 22, a second outer peripheral surface 24, a first inclined surface 26, a third outer peripheral surface 28, and a second inclined surface 30. The diameters of the second outer peripheral surface 24 and the third outer peripheral surface 28 are larger than the diameter of the first outer peripheral surface 22. The diameters of the second outer peripheral surface 24 and the third outer peripheral surface 28 are equal. In a modified example, the diameters of the second outer peripheral surface 24 and the third outer peripheral surface 28 may be different. The second outer peripheral surface 24 is disposed to the left of the first outer peripheral surface 22. The first inclined surface 26 is located between the first outer peripheral surface 22 and the second outer peripheral surface 24 in the axial A direction and connects the first outer peripheral surface 22 and the second outer peripheral surface 24. The diameter of the first inclined surface 26 increases from the first outer peripheral surface 22 to the second outer peripheral surface 24. That is, the diameter of the first inclined surface 26 increases from the right side to the left side. As an example, the inclination angle a1 of the first inclined surface 26 with respect to the axial A direction is 0.1° to 10°. The third outer peripheral surface 28 is located on the right side of the first outer peripheral surface 22. The second inclined surface 30 is located between the first outer peripheral surface 22 and the third outer peripheral surface 28 in the axial A direction and connects the first outer peripheral surface 22 and the third outer peripheral surface 28. The diameter of the second inclined surface 30 increases from the first outer peripheral surface 22 to the third outer peripheral surface 28. That is, the diameter of the second inclined surface 30 increases from the left side to the right side. As an example, the inclination angle a2 of the second inclined surface 30 with respect to the direction of the axis A is 0.1° to 10°. In this embodiment, the inclination angle a2 is equal to the inclination angle a1. In a modified example, the inclination angle a1 and the inclination angle a2 may be different.

[0029] Rotor core 12 is formed by stacking a plurality of identically shaped electromagnetic steel sheets in the direction of axis A. Rotor core 12 has an inner peripheral surface 12A that abuts against a first outer peripheral surface 22 of shaft 10. Rotor core 12 is fixed to shaft 10 by shrink fitting.

[0030] The left end plate 14 and the right end plate 16 are circular plates with a through hole in the center. The left end plate 14 and the right end plate 16 are fixed to the shaft 10 by shrink fitting. The right end plate 16 has a shape that is bilaterally symmetrical to the left end plate 14.

[0031] The inner circumferential surface 14A of the left end plate 14 abuts against the first inclined surface 26 of the shaft 10, and its right surface abuts against the left surface of the rotor core 12. That is, the inner diameter of the left end plate 14 increases from the first outer circumferential surface 22 to the second outer circumferential surface 24. The diameter of the outer circumferential surface of the left end plate 14 is equal to the diameter of the outer circumferential surface of the rotor core 12. The dimension L1 of the inner circumferential surface 14A of the left end plate 14 in the axial direction A is equal to the dimension L1 of the first inclined surface 26 of the shaft 10 in the axial direction A. Furthermore, the positions of the right and left ends of the left end plate 14 coincide with the positions of the right and left ends of the first inclined surface 26, respectively. Therefore, the right end of the left end plate 14 is located on the boundary between the first outer circumferential surface 22 and the first inclined surface 26 of the shaft 10, and the right end of the left end plate 14 is located on the boundary between the first inclined surface 26 and the second outer circumferential surface 24 of the shaft 10. That is, the entire left end plate 14 is positioned on the first inclined surface 26 .

[0032] The right end plate 16 has an inner peripheral surface 16A that abuts against the second inclined surface 30 of the shaft 10, and a right surface that abuts against the right surface of the rotor core 12. That is, the inner diameter of the right end plate 16 increases from the first outer peripheral surface 22 to the third outer peripheral surface 28. The diameter of the outer peripheral surface of the right end plate 16 is equal to the diameter of the outer peripheral surface of the rotor core 12. That is, the diameters of the outer peripheral surfaces of the rotor core 12, the left end plate 14, and the right end plate 16 are equal. The dimension L2 of the inner peripheral surface 16A of the right end plate 16 in the axial A direction is equal to the dimension L2 of the second inclined surface 30 of the shaft 10 in the axial A direction. The dimension L2 of the second inclined surface 30 of the shaft 10 in the axial A direction is equal to the dimension L1 of the first inclined surface 26 in the axial A direction. Therefore, the dimensions L1 and L2 in the axial direction A of the first inclined surface 26, the second inclined surface 30, the inner circumferential surface 14A of the left end plate 14, and the inner circumferential surface 16A of the right end plate 16 of the shaft 10 are equal. Furthermore, the left and right ends of the left end plate 14 are positioned corresponding to the left and right ends of the second inclined surface 30, respectively. Therefore, the left end of the right end plate 16 is located on the boundary between the first outer circumferential surface 22 and the second inclined surface 30 of the shaft 10, and the right end of the right end plate 16 is located on the boundary between the second inclined surface 30 and the third outer circumferential surface 28 of the shaft 10. In other words, the entire right end plate 16 is located on the second inclined surface 30.

[0033] As will be described in detail later, the shaft 10 is elastically deformed radially inward at the first outer peripheral surface 22, the first inclined surface 26, and the second inclined surface 30. A restoring force (reaction force) resulting from the elastic deformation of the first outer peripheral surface 22 acts on the rotor core 12. This restoring force fixes the rotor core 12 to the shaft 10. Furthermore, a restoring force resulting from the elastic deformation of the first inclined surface 26 acts on the left end plate 14, and a restoring force resulting from the elastic deformation of the second inclined surface 30 acts on the right end plate 16. Of these restoring forces, the radial force acts as a tension force, fixing the left end plate 14 and the right end plate 16 to the shaft 10. Furthermore, of the restoring forces, a force acting in the axial A direction clamps the rotor core 12 between the left end plate 14 and the right end plate 16. Specifically, a frictional force resulting from the force acting in the axial A direction fixes the left end plate 14 and the right end plate 16 to the rotor core 12. With this configuration, the shaft 10, rotor core 12, left end plate 14, and right end plate 16 rotate integrally. Note that multiple magnets are provided on the outer peripheral surface of rotor core 12 in the direction of axis A. By fixing left end plate 14 and right end plate 16 to rotor core 12, the multiple magnets are prevented from falling out in the direction of axis A.

[0034] (Method of manufacturing rotor 2) A method for manufacturing the rotor 2 will be described with reference to FIGS.

[0035] First, as shown in FIG. 3 , the rotor core 12 is heated, causing it to temporarily expand radially outward. Specifically, the inner diameter of the rotor core 12 is made larger than the diameter of the second outer peripheral surface 24 of the shaft 10. Next, the rotor core 12 is arranged around the first outer peripheral surface 22 of the shaft 10. Next, the rotor core 12 is cooled, causing it to contract radially inward. As the rotor core 12 contracts radially inward, the first outer peripheral surface 22 of the shaft 10 elastically deforms radially inward. A restoring force resulting from this elastic deformation acts on the rotor core 12. As a result, the rotor core 12 is fixed to the shaft 10, as shown in FIG. 4 .

[0036] Next, the left end plate 14 and the right end plate 16 are heated, thereby temporarily expanding the left end plate 14 and the right end plate 16 radially outward. Specifically, the inner diameters of the left end plate 14 and the right end plate 16 are made larger than the diameter of the second outer peripheral surface 24 of the shaft 10. Next, the left end plate 14 is placed around the first inclined surface 26 of the shaft 10, and the right end plate 16 is placed around the second inclined surface 30 of the shaft 10. The right surface of the left end plate 14 is brought into contact with the left surface of the rotor core 12, and the left surface of the right end plate 16 is brought into contact with the right surface of the rotor core 12. Note that before the left end plate 14 and the right end plate 16 are fixed to the shaft 10, the diameters of the inner peripheral surfaces 14A, 16A of the left end plate 14 and the right end plate 16 are constant in the direction of axis A. Next, the left end plate 14 and the right end plate 16 are cooled, causing the left end plate 14 and the right end plate 16 to contract radially inward. As the left end plate 14 contracts radially inward, the first inclined surface 26 of the shaft 10 elastically deforms radially inward. The inner circumferential surfaces 14A and 16A of the left end plate 14 and the right end plate 16 also elastically deform into shapes corresponding to the first inclined surface 26 and the second inclined surface 30 of the shaft 10, respectively. This is because the rigidity of the left end plate 14 and the right end plate 16 is lower than the rigidity of the shaft 10. Restoring forces resulting from the elastic deformation of the first inclined surface 26 and the second inclined surface 30 of the shaft 10 act on the left end plate 14 and the right end plate 16, respectively. The left end plate 14 and the right end plate 16 are fixed to the shaft 10 and the rotor core 12 by restoring forces such as a radial tension force and a frictional force resulting from a force in the axial A direction. 2 and 4, the amount of elastic deformation of the left end plate 14 and the right end plate 16 increases with increasing distance from the rotor core 12. That is, the amount of elastic deformation of the left end plate 14 is greatest at the left end, and the amount of elastic deformation of the right end plate 16 is greatest at the right end.

[0037] As described above, as shown in FIG. 2 , the rotor 2 of the electric motor includes a shaft 10 extending in the axial direction A, a rotor core 12 fixed to an outer peripheral surface 20 of the shaft 10, and a left end plate 14 (an example of a “first end plate”) fixed to the outer peripheral surface 20 of the shaft 10 and abutting against an end face on the left side (an example of “one axial side”) of the rotor core 12. The outer peripheral surface 20 of the shaft 10 has a first outer peripheral surface 22 abutting against an inner peripheral surface 12A of the rotor core 12, a second outer peripheral surface 24 located to the left of the first outer peripheral surface 22 and having a larger diameter than the first outer peripheral surface 22, and a first inclined surface 26 located between the first outer peripheral surface 22 and the second outer peripheral surface 24 in the axial direction A and abutting against an inner peripheral surface 14A of the left end plate 14. The diameter of the first inclined surface 26 increases from the first outer peripheral surface 22 toward the second outer peripheral surface 24.

[0038] With the above configuration, the left end plate 14 is subjected to not only a radial restoring force (reaction force) from the first inclined surface 26 of the shaft 10, but also a restoring force in the axial direction A (i.e., to the right) toward the rotor core 12. This enables the left end plate 14 to firmly hold the rotor core 12 from the left side. In this way, the first inclined surface 26 of the shaft 10 can be used to fix the left end plate 14 to the shaft 10 and the rotor core 12. This allows the structure for fixing the left end plate 14 to the shaft 10 and the rotor core 12 to be simplified.

[0039] Furthermore, the rotor core 12 and the left end plate 14 can be positioned relative to the shaft 10 in the direction of the axis A by utilizing the first inclined surface 26.

[0040] Furthermore, with the above configuration, the rotor 2 does not need to include an additional member, flange, or the like for fixing the left end plate 14 to the shaft 10 and rotor core 12. In this way, the structure for fixing the left end plate 14 to the shaft 10 and rotor core 12 can be simplified.

[0041] As shown in FIGS. 2 to 4, the shaft 10 is elastically deformed radially inward at least at the first inclined surface 26, and a restoring force resulting from the elastic deformation acts on the left end plate 14.

[0042] According to the above configuration, it is possible to increase the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force resulting from this restoring force.

[0043] As shown in Figures 2 to 4, the left end plate 14 elastically deforms radially outward at least at the inner circumferential surface 14A that abuts the first inclined surface 26, and the amount of elastic deformation of the left end plate 14 increases with increasing distance from the rotor core 12.

[0044] With the above configuration, the restoring force of the left end plate 14 on the side away from the rotor core 12 (i.e., the right side) is greater than the restoring force on the left side. Therefore, the left end plate 14 can firmly hold the rotor core 12 from the left side.

[0045] As shown in FIG. 2, the diameter of the outer peripheral surface of the left end plate 14 is equal to the diameter of the outer peripheral surface of the rotor core 12.

[0046] With the above configuration, the left end plate 14 can firmly hold the rotor core 12 from the right side all the way to the radially outer end. Furthermore, an electromagnetic force acts on the multiple electromagnetic steel sheets that make up the rotor core 12. This electromagnetic force could cause the outer peripheries of the multiple electromagnetic steel sheets to curl up. With the above configuration, the multiple electromagnetic steel sheets that make up the rotor core 12 can be prevented from curling up.

[0047] As shown in FIG. 2, the left edge of the inner circumferential surface 14A of the left end plate 14 is located on the first inclined surface 26 of the shaft 10.

[0048] With the above configuration, compared to a configuration in which the left edge of the inner peripheral surface 14A of the left end plate 14 is located beyond the first inclined surface 26 of the shaft 10 and on the second outer peripheral surface, the restoring force acting from the first inclined surface 26 of the shaft 10 on the left end plate 14 and the frictional force resulting from this restoring force can be increased.

[0049] As shown in FIG. 2, the left edge of the inner circumferential surface 14A of the left end plate 14 is located on the boundary between the second outer circumferential surface 24 and the first inclined surface 26 of the shaft 10.

[0050] The above configuration increases the area over which inner circumferential surface 14A of left end plate 14 contacts first inclined surface 26 of shaft 10. This increases the restoring force acting from first inclined surface 26 of shaft 10 on left end plate 14 and the frictional force resulting from this restoring force.

[0051] As shown in FIG. 2, the dimension L1 of the inner peripheral surface 14A of the left end plate 14 in the axial direction A is equal to the dimension L1 of the first inclined surface 26 of the shaft 10 in the axial direction A.

[0052] According to the above configuration, the area of contact between the inner peripheral surface 14A of the left end plate 14 and the first inclined surface 26 of the shaft 10 can be maximized.

[0053] 2, the rotor 2 further includes a right end plate 16 (an example of a "second end plate") 16 that is fixed to an outer peripheral surface 20 of the shaft 10 and abuts against an end surface on the right side (an example of the "other axial side") of the rotor core 12. The outer peripheral surface 20 of the shaft 10 has a third outer peripheral surface 28 that is located on the right side of the first outer peripheral surface 22 and has a larger diameter than the first outer peripheral surface 22, and a second inclined surface 30 that is located between the first outer peripheral surface 22 and the third outer peripheral surface 28 in the axial A direction and abuts against an inner peripheral surface 14A of the left end plate 14. The diameter of the second inclined surface 30 increases from the first outer peripheral surface 22 toward the third outer peripheral surface 28.

[0054] With the above configuration, not only a radial restoring force but also a restoring force in the axial direction A (i.e., left side) toward the rotor core 12 acts on the right end plate 16 from the second inclined surface 30 of the shaft 10. This enables the right end plate 16 to firmly hold the rotor core 12 from the right side. In other words, the rotor core 12 is firmly held from both sides in the axial direction A by both the left end plate 14 and the right end plate 16.

[0055] As shown in Figures 2 to 4, the manufacturing method of rotor 2 includes a step of temporarily expanding inner circumferential surface 12A of rotor core 12 radially outward to fix rotor core 12 to first outer circumferential surface 22 of shaft 10, and a step of temporarily expanding inner circumferential surface 14A of left end plate 14 radially outward to fix left end plate 14 to first inclined surface 26 of shaft 10.

[0056] According to the above configuration, the left end plate 14 can be tightly fitted onto the shaft 10. This increases the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force resulting from this restoring force. In particular, the left end plate 14 is subjected to not only a radial restoring force from the first inclined surface 26 of the shaft 10, but also a restoring force in the axial A direction (i.e., to the right) toward the rotor core 12. Therefore, the left end plate 14 can firmly hold the rotor core 12 from the left side.

[0057] As shown in FIGS. 2 to 4, the step of fixing the left end plate 14 is carried out after the step of fixing the rotor core 12.

[0058] According to the above configuration, various parameters (for example, temperature) can be appropriately set in each of the steps of fixing the left end plate 14 and fixing the rotor core 12.

[0059] While specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0060] (First Modification) The outer peripheral surface 20 of the shaft 10 may not have one of the first inclined surface 26 and the second inclined surface 30. As an example, if the outer peripheral surface 20 of the shaft 10 does not have the second inclined surface 30, the outer peripheral surface 20 of the shaft 10 may have a flange portion located on the right side of the first outer peripheral surface 22. In this case, the rotor core 12 is held from both sides in the axial A direction by the left end plate 14 abutting against the first inclined surface 26 and the flange portion.

[0061] (Second Modification) Before the left end plate 14 and the right end plate 16 are fixed to the shaft 10, the shapes of the inner circumferential surfaces 14A, 16A of the left end plate 14 and the right end plate 16 may correspond to the first inclined surface 26 and the second inclined surface 30 of the shaft 10, respectively. That is, the diameter of the inner circumferential surface 14A of the left end plate 14 before being fixed to the shaft 10 may increase from the first outer circumferential surface 22 toward the second outer circumferential surface 24. Furthermore, the diameter of the inner circumferential surface 16A of the right end plate 16 before being fixed to the shaft 10 may increase from the first outer circumferential surface 22 toward the third outer circumferential surface 28.

[0062] (Third Modification) The diameter of the outer peripheral surface of the left end plate 14 may be larger than the diameter of the outer peripheral surface of the rotor core 12. In another modification, the diameter of the outer peripheral surface of the left end plate 14 may be smaller than the diameter of the outer peripheral surface of the rotor core 12.

[0063] (Fourth Modification) The left edge of the inner peripheral surface 14A of the left end plate 14 may be located on the second outer peripheral surface 24. In another modification, the left edge of the inner peripheral surface 14A of the left end plate 14 may be located to the right of the boundary between the second outer peripheral surface 24 and the first inclined surface 26.

[0064] (Fifth Modification) The left edge of the inner peripheral surface 14A of the left end plate 14 may be located to the right of the boundary between the first inclined surface 26 and the first outer peripheral surface 22.

[0065] (Sixth Modification) The dimension of the inner peripheral surface 14A of the left end plate 14 in the axial direction A may be longer or shorter than the dimension of the first inclined surface 26 of the shaft 10 in the axial direction A.

[0066] (Seventh Modification) In the method of manufacturing the rotor 2, the step of fixing the left end plate 14 and the step of fixing the rotor core 12 may be performed simultaneously.

[0067] Furthermore, the technical elements described in this specification or drawings may exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings may achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0068] 2: rotor, 10: shaft, 12: rotor core, 14: left end plate, 14A: inner peripheral surface, 16: right end plate, 16A: inner peripheral surface, 20: outer peripheral surface, 22: first outer peripheral surface, 24: second outer peripheral surface, 26: first inclined surface, 28: third outer peripheral surface, 30: second inclined surface, A: shaft, L1: dimension, L2: dimension, a1: inclination angle, a2: inclination angle

Claims

1. A rotor of an electric motor, an axially extending shaft; a rotor core fixed to an outer peripheral surface of the shaft; a first end plate fixed to an outer peripheral surface of the shaft and abutting against an end surface of the rotor core on the one axial side; Equipped with The outer circumferential surface of the shaft is a first outer peripheral surface that abuts on an inner peripheral surface of the rotor core; a second outer circumferential surface located on one side in the axial direction with respect to the first outer circumferential surface and having a larger diameter than the first outer circumferential surface; a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and in contact with an inner peripheral surface of the first end plate, The first inclined surface has a diameter that increases from the first outer peripheral surface toward the second outer peripheral surface. Rotor.

2. The rotor according to claim 1 , wherein the shaft is elastically deformed radially inward at least at the first inclined surface, and a restoring force resulting from the elastic deformation acts on the first end plate.

3. the first end plate is elastically deformed radially outward at least at the inner circumferential surface that contacts the first inclined surface, The rotor according to claim 2 , wherein the amount of elastic deformation of the first end plate increases with increasing distance from the rotor core.

4. The rotor according to claim 1 , wherein a diameter of the outer peripheral surface of the first end plate is larger than or equal to a diameter of the outer peripheral surface of the rotor core.

5. The rotor according to claim 1 , wherein an edge on the one axial side of the inner circumferential surface of the first end plate is positioned on the first inclined surface of the shaft.

6. The rotor according to claim 5 , wherein the edge on the one axial side of the inner circumferential surface of the first end plate is located on a boundary between the second outer circumferential surface of the shaft and the first inclined surface.

7. The rotor according to claim 6 , wherein a dimension in the axial direction of the inner circumferential surface of the first end plate is equal to a dimension in the axial direction of the first inclined surface of the shaft.

8. a second end plate fixed to an outer peripheral surface of the shaft and abutting on an end surface on the other axial side of the rotor core, The outer circumferential surface of the shaft is a third outer peripheral surface located on the other axial side of the first outer peripheral surface and having a larger diameter than the first outer peripheral surface; a second inclined surface located between the first outer peripheral surface and the third outer peripheral surface in the axial direction and in contact with the inner peripheral surface of the first end plate, The rotor according to claim 1 , wherein the second inclined surface has a diameter that increases from the first outer peripheral surface toward the third outer peripheral surface.

9. A method for manufacturing a rotor of an electric motor, comprising: The rotor is an axially extending shaft; a rotor core fixed to an outer peripheral surface of the shaft; a first end plate fixed to an outer peripheral surface of the shaft and abutting against an end surface of the rotor core on the one axial side; Equipped with The outer circumferential surface of the shaft is A first outer circumferential surface; a second outer circumferential surface located on one side in the axial direction with respect to the first outer circumferential surface and having a larger diameter than the first outer circumferential surface; a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction, the first inclined surface having a diameter increasing from the first outer peripheral surface toward the second outer peripheral surface, The manufacturing method includes: a step of temporarily expanding an inner peripheral surface of the rotor core radially outward to fix the rotor core to the first outer peripheral surface of the shaft; a step of temporarily expanding an inner peripheral surface of the first end plate outward in the radial direction to fix the first end plate to the first inclined surface of the shaft; A manufacturing method comprising:

10. The manufacturing method according to claim 9 , wherein the step of fixing the first end plate is performed after the step of fixing the rotor core.

Images