Rotor of electric motor and method for manufacturing same

Abstract

The technology disclosed in the present specification relates to a rotor of an electric motor and a method for manufacturing the same. This rotor for an electric motor is provided with: a shaft; a rotor core fixed to the outer peripheral surface of the shaft; and a first end plate that is fixed to the outer peripheral surface of the shaft and that comes into contact with the end surface of the rotor core. The outer peripheral surface of the shaft has: a first outer peripheral surface that comes into contact with the inner peripheral surface of the rotor core; a second outer peripheral surface located on one side in the axial direction with respect to the first outer peripheral surface and having a diameter larger than that of the first outer peripheral surface; and a first inclined surface located between the first outer peripheral surface and the second outer peripheral surface and abutting against the inner peripheral surface of the first end plate. The diameter of the first inclined surface increases from the first outer peripheral surface toward the second outer peripheral surface.

Description

Technical Field

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

[0002] Japanese Unexamined Patent Application Publication No. 2008-109804 discloses a rotor of an electric motor. The 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 an end surface on one axial side of the rotor core; and an anti-rotation member fixed to the outer peripheral surface of the shaft and abutting against an end surface on one axial side of the end plate.

[0003] In the rotor of Japanese Unexamined Patent Application Publication No. 2008-109804, a frictional force is generated between the anti-rotation member and the end plate by the anti-rotation member abutting against the end surface on one axial side of the end plate. By this frictional force, the end plate is fixed relative to the shaft and the rotor core. A technology capable of simplifying the structure for fixing the end plate relative to the shaft and the rotor core is desired. Summary of the Invention

[0004] In this specification, a technology capable of simplifying the structure for fixing the end plate relative to the shaft and the rotor core is provided.

[0005] In a first aspect of the present technology, a rotor of an electric motor may also include: a shaft extending in the 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 against an end surface on one axial side of the rotor core. The outer peripheral surface of the shaft may also have: a first outer peripheral surface abutting against the inner peripheral surface of the rotor core; a second outer peripheral surface located on one axial side with respect to the first outer peripheral surface and having a diameter larger than that of 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 against the inner peripheral surface of the first end plate. The diameter of the first inclined surface may increase as it goes from the first outer peripheral surface toward the second outer peripheral surface.

[0006] According to the above technical solution, in the first end plate, not only a radial restoring force (reaction force) but also a restoring force in the axial direction (i.e., the other axial side) toward the rotor core acts from the first inclined surface of the shaft. Thus, the first end plate can 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 relative to the shaft and the rotor core. Therefore, the structure for fixing the end plate relative to the shaft and the rotor core can be simplified.

[0007] In the second technical solution, it can also be configured that, on the basis of the above first technical solution, the shaft elastically deforms at least inward in the radial direction on the above first inclined surface, and the restoring force caused by the elastic deformation acts on the above first end plate. In other words, the above first end plate can also be press-fitted with interference relative to the above shaft.

[0008] According to the above technical solution, the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force caused by the restoring force can be increased. In addition, although it is an example, the above structure can be realized by hot press fitting, cooling fitting, press fitting, etc.

[0009] In the third technical solution, it can also be configured that, on the basis of the above second technical solution, the first end plate elastically deforms at least outward in the radial direction on the inner peripheral surface in contact with the above first inclined surface, and the amount of the elastic deformation of the first end plate increases as it is farther away from the above rotor core.

[0010] According to the above technical solution, in the first end plate, the restoring force on the other side in the axial direction is greater than the restoring force on one side in the axial direction. Therefore, the first end plate can firmly hold the rotor core from one side in the axial direction.

[0011] In the fourth technical solution, it can also be configured that, on the basis of any one of the above first to third technical solutions, the diameter of the outer peripheral surface of the above first end plate is greater than or equal to the diameter of the outer peripheral surface of the above rotor core.

[0012] According to the above technical solution, the first end plate can firmly hold the rotor core from one side in the axial direction to the end portion on the outer side in the radial direction.

[0013] In the fifth technical solution, it can also be configured that, on the basis of any one of the above first to fourth technical solutions, the end edge on the above axial one side of the above inner peripheral surface of the above first end plate is located on the above first inclined surface of the above shaft. The "on the above first inclined surface" mentioned here also includes the boundary between the first inclined surface and the second outer peripheral surface.

[0014] According to the above technical solution, compared with the structure in which the end edge on the axial one side of the inner peripheral surface of the first end plate is located on the second outer peripheral surface across the first inclined surface of the shaft, the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force caused by the restoring force can be increased.

[0015] In the sixth technical solution, it can also be configured that, on the basis of the above fifth technical solution, the end edge on the above axial one side of the above inner peripheral surface of the above first end plate is located at the boundary between the above second outer peripheral surface and the above first inclined surface of the above shaft.

[0016] According to the above technical solution, the contact area between the inner peripheral surface of the first end plate and the first inclined surface of the shaft can be increased. Thereby, the restoring force acting on the first end plate from the first inclined surface of the shaft and the frictional force caused by the restoring force can be increased.

[0017] In the seventh technical solution, it may also be configured that, based on the sixth technical solution, the dimension of the inner peripheral surface of the first end plate in the axial direction is equal to the dimension of the first inclined surface of the shaft in the axial direction.

[0018] According to the above technical solution, the maximization of the contact area between the inner peripheral surface of the first end plate and the first inclined surface of the shaft can be achieved.

[0019] In the eighth technical solution, it may also be configured that, based on any one of the first to seventh technical solutions, the rotor further includes a second end plate fixed to the outer peripheral surface of the shaft and abutted against the end surface on the other axial side of the rotor core. The outer peripheral surface of the shaft may also have: a third outer peripheral surface located on the other axial side with respect to the first outer peripheral surface and having a diameter larger than that of 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 abutted against the inner peripheral surface of the second end plate. It may also be that the diameter of the second inclined surface increases as it goes from the first outer peripheral surface toward the third outer peripheral surface.

[0020] According to the above technical solution, in the second end plate, not only a radial restoring force (reaction force) acts from the second inclined surface of the shaft, but also a restoring force toward the axial direction (i.e., the axial one side) of the rotor core acts. Thereby, the second end plate can firmly hold the rotor core from the other axial side. That is, through both the first end plate and the second end plate, the rotor core is firmly held from both axial sides.

[0021] In the ninth technical solution of the present technology, a manufacturing method of a rotor of an electric motor is disclosed. The above rotor may also include: a shaft extending in the axial direction; a rotor core fixed to the outer peripheral surface of the above shaft; and a first end plate fixed to the outer peripheral surface of the above shaft and abutting against the end surface on the above axial one side of the above rotor core. The outer peripheral surface of the above shaft may also have: a first outer peripheral surface; a second outer peripheral surface located on the above axial one side with respect to the above first outer peripheral surface and having a diameter larger than that of the above first outer peripheral surface; and a first inclined surface located between the above first outer peripheral surface and the above second outer peripheral surface in the above axial direction and having a diameter that increases as it goes from the above first outer peripheral surface toward the above second outer peripheral surface. The above manufacturing method may also include: a step of temporarily expanding the inner peripheral surface of the above rotor core radially outward to fix the above rotor core to the above first outer peripheral surface of the above shaft; and a step of temporarily expanding the inner peripheral surface of the above first end plate radially outward to fix the above first end plate to the above first inclined surface of the above shaft.

[0022] According to the above technical solution, the first end plate can be interference-fitted to the shaft. Thereby, the restoring force (reaction force) acting on the first end plate from the first inclined surface of the shaft and the frictional force caused by the restoring force can be increased. Especially in the first end plate, not only a radial restoring force but also a restoring force toward the axial direction (i.e., the other axial side) of the rotor core acts from the first inclined surface of the shaft. Therefore, the first end plate can firmly hold the rotor core from the axial one side.

[0023] In the tenth technical solution, it may also be configured that, on the basis of the above ninth technical solution, the step of fixing the above first end plate is carried out after the step of fixing the above rotor core.

[0024] According to the above technical solution, various parameters can be appropriately set respectively in the step of fixing the first end plate and the step of fixing the rotor core.

[0025] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present invention will be described. In the drawings, the same reference numerals denote the same elements. Description of the Drawings

[0026] Figure 1 It is a cross-sectional view of the rotor 2.

[0027] Figure 2 It is Figure 1 a partial enlarged view of the rotor 2.

[0028] Figure 3 It is a view showing the step of installing the rotor 2 on the shaft 10 in the manufacturing method of the rotor 2.

[0029] Figure 4This is a diagram showing the process of installing the left end plate 14 and the right end plate 16 on the shaft 10 in the manufacturing method of the rotor 2. Detailed implementation

[0030] Refer to Figure 1 , Figure 2 , the rotor 2 will be described. The rotor 2 is a rotor of an electric motor mounted on an electric vehicle or the like. In addition, the up-down direction and the left-right direction in each drawing are marked for easy understanding of the description and do not specify the actual direction.

[0031] As Figure 1 shown, the rotor 2 includes a shaft 10 extending in the axial direction A, a rotor core 12, a left end plate 14, and a right end plate 16. The axial direction A is parallel to the left-right direction. As Figure 2 shown, the shaft 10 includes an outer peripheral surface 20, and the outer peripheral surface 20 includes 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 diameter of the second outer peripheral surface 24 is equal to the diameter of the third outer peripheral surface 28. In a modified example, the diameters of the second outer peripheral surface 24 and the third outer peripheral surface 28 may also be different. The second outer peripheral surface 24 is disposed on the left side with respect to 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 direction A and connects the first outer peripheral surface 22 and the second outer peripheral surface 24. For the first inclined surface 26, the diameter increases as it goes from the first outer peripheral surface 22 toward the second outer peripheral surface 24. That is, for the first inclined surface 26, the diameter increases as it goes from the right side toward the left side. Although it is an example, the inclination angle a1 of the first inclined surface 26 with respect to the axial direction A is 0.1° to 10°. The third outer peripheral surface 28 is disposed on the right side with respect to 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 direction A and connects the first outer peripheral surface 22 and the third outer peripheral surface 28. For the second inclined surface 30, the diameter increases as it goes from the first outer peripheral surface 22 toward the third outer peripheral surface 28. That is, for the second inclined surface 30, the diameter increases as it goes from the left side toward the right side. Although it is an example, the inclination angle a2 of the second inclined surface 30 with respect to the axial direction A is 0.1° to 10°. In the present 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 also be different.

[0032] The rotor core 12 is formed by laminating a plurality of electromagnetic steel sheets of the same shape in the axial direction A. The inner peripheral surface 12A of the rotor core 12 abuts against the first outer peripheral surface 22 of the shaft 10. The rotor core 12 is fixed to the shaft 10 by hot press fitting.

[0033] The left end plate 14 and the right end plate 16 are circular plates with a through hole provided in the center. The left end plate 14 and the right end plate 16 are fixed to the shaft 10 by hot press fitting. The right end plate 16 has a shape that is symmetric about the left and right with respect to the left end plate 14.

[0034] The inner peripheral 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 as it goes from the first outer peripheral surface 22 toward the second outer peripheral surface 24. 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. The dimension L1 of the inner peripheral surface 14A of the left end plate 14 in the axial direction of the axis A is equal to the dimension L1 of the first inclined surface 26 of the shaft 10 in the axial direction of the axis A. In addition, the positions of the right end and the left end of the left end plate 14 coincide with the positions of the right end and the left end of the first inclined surface 26, respectively. Therefore, the right end of the left end plate 14 is located at the boundary between the first outer peripheral surface 22 and the first inclined surface 26 of the shaft 10, and the left end of the left end plate 14 is located at the boundary between the first inclined surface 26 and the second outer peripheral surface 24 of the shaft 10. That is, the entire left end plate 14 is located on the first inclined surface 26.

[0035] The inner peripheral surface 16A of the right end plate 16 abuts against the second inclined surface 30 of the shaft 10, and its left surface abuts against the right surface of the rotor core 12. That is, the inner diameter of the right end plate 16 increases as it goes from the first outer peripheral surface 22 toward 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 direction of the axis A is equal to the dimension L2 of the second inclined surface 30 of the shaft 10 in the axial direction of the axis A. The dimension L2 of the second inclined surface 30 of the shaft 10 in the axial direction of the axis A is equal to the dimension L1 of the first inclined surface 26 in the axial direction of the axis A. Therefore, the dimensions L1 and L2 of the first inclined surface 26, the second inclined surface 30, the inner peripheral surface 14A of the left end plate 14, and the inner peripheral surface 16A of the right end plate 16 in the axial direction of the axis A are equal. In addition, the positions of the left end and the right end of the right end plate 16 coincide with the positions of the left end and the right end of the second inclined surface 30, respectively. Therefore, the left end of the right end plate 16 is located at the boundary between the first outer peripheral surface 22 and the second inclined surface 30 of the shaft 10, and the right end of the right end plate 16 is located at the boundary between the second inclined surface 30 and the third outer peripheral surface 28 of the shaft 10. That is, the entire right end plate 16 is located on the second inclined surface 30.

[0036] The shaft 10 elastically deforms inward in the radial direction at the first outer peripheral surface 22, the first inclined surface 26, and the second inclined surface 30. Details will be described later. Moreover, a restoring force (reaction force) caused by the elastic deformation of the first outer peripheral surface 22 acts on the rotor core 12. By this restoring force, the rotor core 12 is fixed relative to the shaft 10. In addition, a restoring force caused by the elastic deformation of the first inclined surface 26 acts on the left end plate 14, and a restoring force caused by the elastic deformation of the second inclined surface 30 acts on the right end plate 16. The radial forces among these restoring forces become preloading forces, and the left end plate 14 and the right end plate 16 are fixed relative to the shaft 10. In addition, by means of the force in the direction of axis A in the restoring force, the rotor core 12 is clamped by the left end plate 14 and the right end plate 16. Specifically, by means of the frictional force caused by the force in the direction of axis A, the left end plate 14 and the right end plate 16 are fixed relative to the rotor core 12. With such a structure, the shaft 10, the rotor core 12, the left end plate 14, and the right end plate 16 rotate integrally. In addition, a plurality of magnets are provided on the outer peripheral surface of the rotor core 12 in the direction of axis A. By fixing the left end plate 14 and the right end plate 16 relative to the rotor core 12, the plurality of magnets are prevented from falling off in the direction of axis A.

[0037] <Manufacturing method of rotor 2>

[0038] Refer to Figures 2 to 4 , and the manufacturing method of the rotor 2 will be described.

[0039] First, as Figure 3 shown, by heating the rotor core 12, the rotor core 12 is temporarily expanded outward in the radial direction. 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 disposed near the first outer peripheral surface 22 of the shaft 10. Next, by cooling the rotor core 12, the rotor core 12 contracts inward in the radial direction. Corresponding to the inward contraction of the rotor core 12 in the radial direction, the first outer peripheral surface 22 of the shaft 10 elastically deforms inward in the radial direction. Moreover, a restoring force caused by this elastic deformation acts on the rotor core 12. As a result, as Figure 4 shown, the rotor core 12 is fixed relative to the shaft 10.

[0040] Next, by heating the left end plate 14 and the right end plate 16, the left end plate 14 and the right end plate 16 are temporarily expanded outward in the radial direction. 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 disposed near the first inclined surface 26 of the shaft 10, and the right end plate 16 is disposed near the second inclined surface 30 of the shaft 10. In addition, 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. Further, in a state 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 and 16A of the left end plate 14 and the right end plate 16 are constant in the axial direction of the shaft A. Next, by cooling the left end plate 14 and the right end plate 16, the left end plate 14 and the right end plate 16 are contracted inward in the radial direction. Corresponding to the inward contraction of the left end plate 14 in the radial direction, the first inclined surface 26 of the shaft 10 elastically deforms inward in the radial direction. In addition, the inner peripheral surfaces 14A and 16A of the left end plate 14 and the right end plate 16 are also elastically deformed 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 smaller than the rigidity of the shaft 10. Moreover, the restoring forces caused by the elastic deformations 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. Next, by the restoring forces such as the radial preloading force and the frictional force caused by the force in the axial direction of the shaft A, the left end plate 14 and the right end plate 16 are fixed relative to the shaft 10 and the rotor core 12. In addition, by Figure 2 , Figure 4 It can be seen that the amount of elastic deformation of the left end plate 14 and the right end plate 16 increases as they are farther away from the rotor core 12. That is, the amount of elastic deformation of the left end plate 14 is the largest at the left end portion, and the amount of elastic deformation of the right end plate 16 is the largest at the right end portion.

[0041] As described above, as Figure 2 shown, the rotor 2 of the electric motor includes: a shaft 10 extending in the axial direction of the shaft A; a rotor core 12 fixed to the outer peripheral surface 20 of the shaft 10; and a left end plate 14 (an example of the "first end plate") fixed to the outer peripheral surface 20 of the shaft 10 and in contact with the end surface on the left side (an example of the "axial one side") of the rotor core 12. The outer peripheral surface 20 of the shaft 10 has: a first outer peripheral surface 22 in contact with the inner peripheral surface 12A of the rotor core 12; a second outer peripheral surface 24 located on the left side with respect to the first outer peripheral surface 22 and having a diameter larger than that of 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 of the shaft A and in contact with the inner peripheral surface 14A of the left end plate 14. As the first inclined surface 26 extends from the first outer peripheral surface 22 toward the second outer peripheral surface 24, the diameter of the first inclined surface 26 increases.

[0042] According to the above structure, on the left end plate 14, from the first inclined surface 26 of the shaft 10, not only a radial restoring force (reaction force) acts, but also a restoring force in the axial direction A of the rotor core 12 (i.e., to the right) acts. Thus, the left end plate 14 can firmly hold the rotor core 12 from the left side. In this way, the left end plate 14 can be fixed relative to the shaft 10 and the rotor core 12 by using the first inclined surface 26 of the shaft 10. Therefore, the structure for fixing the left end plate 14 relative to the shaft 10 and the rotor core 12 can be simplified.

[0043] In addition, the first inclined surface 26 can be used to position the rotor core 12 and the left end plate 14 in the axial direction A of the shaft 10.

[0044] Moreover, according to the above structure, the rotor 2 may not have additional components, flanges, etc. for fixing the left end plate 14 relative to the shaft 10 and the rotor core 12. In this way, the structure for fixing the left end plate 14 relative to the shaft 10 and the rotor core 12 can be simplified.

[0045] In addition, as Figures 2 to 4 shown, the shaft 10 is at least elastically deformed radially inward on the first inclined surface 26, and the restoring force caused by the elastic deformation acts on the left end plate 14.

[0046] According to the above structure, the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force caused by this restoring force can be increased.

[0047] In addition, as Figures 2 to 4 shown, the left end plate 14 is at least elastically deformed radially outward on the inner peripheral surface 14A in contact with the first inclined surface 26, and the amount of elastic deformation of the left end plate 14 increases as it moves away from the rotor core 12.

[0048] According to the above structure, on the left end plate 14, the restoring force on the side away from the rotor core 12 (i.e., the left side) is greater than the restoring force on the right side. Therefore, the left end plate 14 can firmly hold the rotor core 12 from the left side.

[0049] In addition, as Figure 2 shown, 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.

[0050] According to the above structure, the left end plate 14 can be firmly held from the left side to the radially outer end of the rotor core 12. In addition, electromagnetic force acts on the plurality of electromagnetic steel sheets constituting the rotor core 12. Due to this electromagnetic force, the outer peripheral portions of the plurality of electromagnetic steel sheets may be curled. According to the above structure, curling of the plurality of electromagnetic steel sheets constituting the rotor core 12 can be suppressed.

[0051] In addition, asFigure 2 As shown, the left end edge of the inner peripheral surface 14A of the left end plate 14 is located on the first inclined surface 26 of the shaft 10.

[0052] According to the above structure, compared with the structure in which the left end edge of the inner peripheral surface 14A of the left end plate 14 is located on the second outer peripheral surface across the first inclined surface 26 of the shaft 10, the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force caused by this restoring force can be increased.

[0053] In addition, as Figure 2 shown, the left end edge of the inner peripheral surface 14A of the left end plate 14 is located at the boundary between the second outer peripheral surface 24 and the first inclined surface 26 of the shaft 10.

[0054] According to the above structure, the contact area between the inner peripheral surface 14A of the left end plate 14 and the first inclined surface 26 of the shaft 10 can be increased. Thus, the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force caused by this restoring force can be increased.

[0055] In addition, as Figure 2 shown, 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.

[0056] According to the above structure, the contact area 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.

[0057] In addition, as Figure 2 shown, the rotor 2 further includes a right end plate 16 (an example of the "second end plate"), which is fixed to the outer peripheral surface 20 of the shaft 10 and abuts against the end surface on the right side (an example of the "axial other side") of the rotor core 12. The outer peripheral surface 20 of the shaft 10 has: a third outer peripheral surface 28, which is located on the right side relative to the first outer peripheral surface 22 and has a diameter larger than that of the first outer peripheral surface 22; and a second inclined surface 30, which is located between the first outer peripheral surface 22 and the third outer peripheral surface 28 in the axial direction A and abuts against the inner peripheral surface 16A of the right end plate 16. As the diameter of the second inclined surface 30 increases from the first outer peripheral surface 22 toward the third outer peripheral surface 28.

[0058] According to the above structure, in the right end plate 16, not only a radial restoring force but also a restoring force in the axial direction A (i.e., the left side) of the rotor core 12 acts from the second inclined surface 30 of the shaft 10. Thus, the right end plate 16 can firmly hold the rotor core 12 from the right side. That is, through both the left end plate 14 and the right end plate 16, the rotor core 12 is firmly held from both sides in the axial direction A.

[0059] AsFigures 2 to 4 As shown in the figure, the manufacturing method of the rotor 2 includes a process of temporarily expanding the inner peripheral surface 12A of the rotor core 12 radially outward to fix the rotor core 12 to the first outer peripheral surface 22 of the shaft 10, and a process of temporarily expanding the inner peripheral surface 14A of the left end plate 14 radially outward to fix the left end plate 14 to the first inclined surface 26 of the shaft 10.

[0060] According to the above structure, the left end plate 14 can be interference-fitted to the shaft 10. Thus, the restoring force acting on the left end plate 14 from the first inclined surface 26 of the shaft 10 and the frictional force caused by the restoring force can be increased. Particularly in the left end plate 14, not only a radial restoring force but also a restoring force in the axial direction A (i.e., to the right) of the rotor core 12 acts from the first inclined surface 26 of the shaft 10. Therefore, the left end plate 14 can firmly hold the rotor core 12 from the left side.

[0061] In addition, as Figures 2 to 4 shown, the process of fixing the left end plate 14 is carried out after the process of fixing the rotor core 12.

[0062] According to the above structure, various parameters (e.g., temperature) can be appropriately set respectively in the process of fixing the left end plate 14 and the process of fixing the rotor core 12.

[0063] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the claims. The technology described in the claims includes technologies obtained by various deformations and changes to the above-described specific examples.

[0064] <First Modification Example>

[0065] Either the first inclined surface 26 or the second inclined surface 30 may not be provided on the outer peripheral surface 20 of the shaft 10. Although it is an example, when the second inclined surface 30 is not provided on the outer peripheral surface 20 of the shaft 10, 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 direction A by the left end plate 14 in contact with the first inclined surface 26 and the flange portion.

[0066] <Second Modification Example>

[0067] It can also be configured such that, in a state before the left end plate 14 and the right end plate 16 are fixed to the shaft 10, the shapes of the inner peripheral surfaces 14A and 16A of the left end plate 14 and the right end plate 16 respectively have shapes corresponding to the first inclined surface 26 and the second inclined surface 30 of the shaft 10. That is, the diameter of the inner peripheral surface 14A of the left end plate 14 before being fixed to the shaft 10 can also increase as it goes from the first outer peripheral surface 22 toward the second outer peripheral surface 24. In addition, the diameter of the inner peripheral surface 16A of the right end plate 16 before being fixed to the shaft 10 can also increase as it goes from the first outer peripheral surface 22 toward the third outer peripheral surface 28.

[0068] <Third Variant Example>

[0069] The diameter of the outer peripheral surface of the left end plate 14 can also be larger than the diameter of the outer peripheral surface of the rotor core 12. In another variant example, the diameter of the outer peripheral surface of the left end plate 14 can also be smaller than the diameter of the outer peripheral surface of the rotor core 12.

[0070] <Fourth Variant Example>

[0071] The left end edge of the inner peripheral surface 14A of the left end plate 14 can also be located on the second outer peripheral surface 24. In addition, in another variant example, the left end edge of the inner peripheral surface 14A of the left end plate 14 can also be located at a position to the right of the boundary between the second outer peripheral surface 24 and the first inclined surface 26.

[0072] <Fifth Variant Example>

[0073] The left end edge of the inner peripheral surface 14A of the left end plate 14 can also be located at a position to the right of the boundary between the first inclined surface 26 and the first outer peripheral surface 22.

[0074] <Sixth Variant Example>

[0075] The dimension of the inner peripheral surface 14A of the left end plate 14 in the axial direction A can be longer than the dimension of the first inclined surface 26 of the shaft 10 in the axial direction A, or can also be shorter than it.

[0076] <Seventh Variant Example>

[0077] In the manufacturing method of the rotor 2, the process of fixing the left end plate 14 and the process of fixing the rotor core 12 can also be performed simultaneously.

[0078] In addition, the technical elements described in this specification or the drawings exhibit technical usefulness either individually or through various combinations, and are not limited to the combinations recited in the claims at the time of application. In addition, the technologies exemplified in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of the purposes itself has technical usefulness.

Claims

1. A rotor, which is a rotor of an electric motor, wherein, the rotor includes: a shaft extending in the 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 against the end surface on the axial side of the rotor core, the outer peripheral surface of the shaft has: a first outer peripheral surface abutting against the inner peripheral surface of the rotor core; a second outer peripheral surface located on the axial side with respect to the first outer peripheral surface and having a diameter larger than that of 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 against the inner peripheral surface of the first end plate, the diameter of the first inclined surface increases as it goes from the first outer peripheral surface toward the second outer peripheral surface.

2. The rotor according to claim 1, wherein, the shaft elastically deforms at least radially inward of the first inclined surface, and the restoring force caused by the elastic deformation acts on the first end plate.

3. The rotor according to claim 2, wherein, the first end plate elastically deforms at least radially outward of the inner peripheral surface abutting against the first inclined surface, the amount of elastic deformation of the first end plate increases as it moves away from the rotor core.

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

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

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

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

8. The rotor according to any one of claims 1 to 7, wherein, it further includes a second end plate fixed to the outer peripheral surface of the shaft and abutting against the end surface on the other axial side of the rotor core, the outer peripheral surface of the shaft has: a third outer peripheral surface located on the other axial side with respect to the first outer peripheral surface and having a diameter larger than that of 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 against the inner peripheral surface of the first end plate, the diameter of the second inclined surface increases as it goes from the first outer peripheral surface toward the third outer peripheral surface.

9. A manufacturing method, which is a manufacturing method of a rotor of an electric motor, wherein, the rotor includes: a shaft extending in the 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 against the end surface on the axial side of the rotor core, the outer peripheral surface of the shaft has: a first outer peripheral surface; A second outer peripheral surface, which is located on the axial side with respect to the first outer peripheral surface and has a diameter larger than that of the first outer peripheral surface; and A first inclined surface, which is located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and has a diameter that increases as it goes from the first outer peripheral surface toward the second outer peripheral surface, The manufacturing method includes: A step of temporarily expanding the inner peripheral surface of the rotor core radially outward to fix the rotor core to the first outer peripheral surface of the shaft; and A step of temporarily expanding the inner peripheral surface of the first end plate radially outward to fix the first end plate to the first inclined surface of the shaft.

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.

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