Rotor and method for producing rotor / shaft assembly

Abstract

A rotor (12) comprises a rotor core (16) that has a press-fitting hole (26) into which a shaft (14) is press-fitted and a cover (20) that covers an axial-direction end surface (24) of the rotor core. A space (32) that is surrounded by the axial-direction end surface and the cover is formed in a peripheral portion of an opening (26A) of the press-fitting hole on the axial-direction end surface side.

Description

Method for manufacturing rotor and rotor-shaft assembly CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from Japanese Patent Application No. 2024-088307, filed on May 30, 2024, the entire contents of which are incorporated herein by reference.

[0002] The disclosed technology relates to methods of manufacturing rotors and rotor shaft assemblies.

[0003] In the technical field of rotors and manufacturing methods for rotor-shaft assemblies, a rotor-shaft assembly having a rotor and a shaft is known (see, for example, Japanese Patent Application Laid-Open No. 2021-197880). In this rotor-shaft assembly, the rotor has a rotor core, and the rotor core has a press-fit hole into which the shaft is press-fit.

[0004] As a result of detailed investigations by the inventors, the following problem was found: In the rotor-shaft assembly described above, there is a risk that burrs may be generated from the rotor core when the shaft is press-fitted into the press-fit hole, and the burrs may fly off.

[0005] The technique of the present disclosure provides a method for manufacturing a rotor and a rotor-shaft assembly that can suppress the scattering of burrs generated from the rotor core.

[0006] A first aspect of the technology of the present disclosure is a rotor having a rotor core having a press-fit hole into which a shaft is press-fitted, and a cover covering the axial end face of the rotor core, wherein a space surrounded by the axial end face and the cover is formed around the opening of the press-fit hole on the axial end face side.

[0007] A second aspect of the technology of the present disclosure is a method for manufacturing a rotor-shaft assembly having a rotor and a shaft, the method comprising: a cover attachment process in which a cover that covers the axial end face of a rotor core of the rotor is attached to the rotor core and forms a space surrounded by the axial end face and the cover around the opening of a press-fit hole in the rotor core on the axial end face side; and a shaft press-fit process in which the shaft is press-fitted into the press-fit hole and burrs generated from the rotor core during press-fitting are confined within the space.

[0008] According to the technique of the present disclosure, a method for manufacturing a rotor and a rotor-shaft assembly that can suppress the scattering of burrs generated from the rotor core is provided.

[0009] Fig. 1 is a perspective view showing an assembled state of the rotor shaft assembly according to the first embodiment. Fig. 2 is a perspective view showing an exploded state of the rotor shaft assembly according to the first embodiment. Fig. 3 is a longitudinal cross-section of the rotor shaft assembly according to the first embodiment. Fig. 4 is a longitudinal cross-section of the rotor shaft assembly according to the second embodiment. Fig. 5 is a longitudinal cross-section of the rotor shaft assembly according to the third embodiment. Fig. 6 is a perspective view showing an exploded state of the rotor shaft assembly according to the fourth embodiment. Fig. 7 is a longitudinal cross-section of the rotor shaft assembly according to the fourth embodiment.

[0010] First Embodiment First, a first embodiment of the technology of the present disclosure will be described.

[0011] As shown in Figures 1 and 2, a rotor-shaft assembly 10 according to the first embodiment includes a rotor 12 and a shaft 14. The rotor 12 is an interior permanent magnet (IPM) type rotor used in an inner rotor type brushless motor. The rotor 12 includes a rotor core 16, a plurality of magnets 18, a first cover 20, and a second cover 21. The first cover 20 is an example of a "cover" according to the technology of the present disclosure.

[0012] The rotor core 16 is a laminated body formed by stacking a plurality of core sheets 22 in the axial direction of the rotor core 16. The outer peripheral surface of the rotor core 16 is formed in a circular shape when viewed from the axial direction of the rotor core 16. The rotor core 16 has a first axial end face 24 and a second axial end face 25. The first axial end face 24 is an end face on one axial side of the rotor core 16, and the second axial end face 25 is an end face on the other axial side of the rotor core 16. The first axial end face is an example of an "axial end face" according to the technology of the present disclosure.

[0013] The rotor core 16 has a press-fit hole 26 and a plurality of accommodating holes 28. The press-fit hole 26 and the plurality of accommodating holes 28 penetrate the rotor core 16 in the axial direction. That is, the press-fit hole 26 opens to a first axial end face 24 and a second axial end face 25. Similarly, the plurality of accommodating holes 28 open to the first axial end face 24 and the second axial end face 25. The shaft 14 is press-fitted into the press-fit hole 26. The press-fit hole 26 is formed in the center of the rotor core 16.

[0014] The multiple accommodating holes 28 are aligned in the circumferential direction of the rotor core 16 along the outer peripheral surface of the rotor core 16. The multiple accommodating holes 28 are located closer to the outer peripheral surface than the center of the rotor core 16. The multiple magnets 18 are embedded in the rotor core 16 by being accommodated in the multiple accommodating holes 28, respectively.

[0015] The first cover 20 is attached to the first axial end surface 24, thereby covering the first axial end surface 24. The first cover 20 is formed in a disk shape having the same size as the first axial end surface 24. The first cover 20 covers the first axial end surface 24, thereby closing the multiple accommodating holes 28.

[0016] Similarly, the second cover 21 is attached to the second axial end face 25 to cover the second axial end face 25. The second cover 21 is formed in a disk shape having the same size as the second axial end face 25. The second cover 21 covers the first axial end face 25, thereby closing the multiple accommodating holes 28. Unlike the first cover 20, the second cover 21 has a flat shape that does not have a throttle portion 34, which will be described later, but is otherwise similar in configuration to the first cover 20.

[0017] The first cover 20 has a loose insertion hole 30. The loose insertion hole 30 is formed in the center of the first cover 20 and penetrates the first cover 20 in the plate thickness direction. The shaft 14 is loosely inserted into the loose insertion hole 30. That is, the shaft 14 is inserted into the loose insertion hole 30 with a small gap between the outer circumferential surface of the shaft 14 and the inner circumferential surface of the loose insertion hole 30. The first cover 20 is made of metal. The metal forming the first cover 20 may be any metal, such as aluminum.

[0018] 3 , a space 32 surrounded by the first axial end face 24 and the first cover 20 is formed around the opening 26A of the press-fit hole 26 on the first axial end face 24 side. The space 32 is a space for trapping burrs generated from the rotor core 16 when the shaft 14 is press-fitted into the press-fit hole 26.

[0019] The first cover 20 has a drawn portion 34 formed by drawing. The drawn portion 34 is formed in a shape that is convex on the side opposite to the first axial end face 24 (i.e., the side indicated by arrow A). The drawn portion 34 is formed in an annular shape around the opening 26A of the press-fit hole 26 on the side of the first axial end face 24. Specifically, the space 32 is formed by being surrounded by the first axial end face 24 and the drawn portion 34. The space 32 is formed in an annular shape around the opening 26A of the press-fit hole 26 on the side of the first axial end face 24.

[0020] 2, when the inner diameter of the press-fit hole 26 is Da, the inner diameter of the loose insertion hole 30 is Db, and the outer diameter of the shaft 14 is Ds, the inner diameter Da of the press-fit hole 26 is set to a dimension such that the inner diameter Da < the outer diameter Ds. Furthermore, when the allowable upper limit dimension of burrs is Δd, the inner diameter Db of the loose insertion hole 30 is set to a dimension such that the outer diameter Ds < the inner diameter Db < the outer diameter Ds + Δd. The allowable upper limit dimension Δd of burrs can be set arbitrarily.

[0021] Next, a method for manufacturing the rotor-shaft assembly 10 according to the first embodiment will be described.

[0022] The method for manufacturing the rotor-shaft assembly 10 according to the first embodiment includes a cover mounting step and a shaft press-fitting step.

[0023] The cover mounting process is a process of mounting a first cover 20 that covers the first axial end face 24 of the rotor core 16 to the rotor core 16, and forming a space 32 surrounded by the first axial end face 24 and the first cover 20 around the opening 26A on the first axial end face 24 side of the press-fit hole 26.

[0024] The shaft press-fitting process is a process of press-fitting the shaft 14 into the press-fit hole 26 and confining burrs generated from the rotor core 16 during the press-fitting process in the space 32. The shaft 14 is press-fitted into the press-fit hole 26 from the other axial side of the rotor core 16.

[0025] As described above, according to the first embodiment, a space 32 surrounded by the first axial end face 24 and the first cover 20 is formed around the opening 26A of the press-fit hole 26 on the side of the first axial end face 24. Therefore, even if burrs are generated from the rotor core 16 when the shaft 14 is press-fitted into the press-fit hole 26 in the shaft press-fitting step, the burrs can be contained in the space 32, thereby preventing the burrs from scattering.

[0026] Furthermore, the first cover 20 is formed by drawing and has a drawn portion 34 that is convex on the side opposite to the first axial end face 24, and the space 32 is formed by being surrounded by the first axial end face 24 and the drawn portion 34. Therefore, with the simple structure of forming the drawn portion 34 in the first cover 20, the space 32 for trapping burrs can be formed.

[0027] Furthermore, since the first cover 20 is made of metal, the narrowed portion 34 can be easily formed at low cost.

[0028] Furthermore, since the shaft 14 is loosely inserted into the loose insertion hole 30 of the first cover 20 , it is possible to prevent burrs from being generated on the first cover 20 when the shaft 14 is loosely inserted into the loose insertion hole 30 .

[0029] Furthermore, the first cover 20 is a cover for covering the multiple storage holes 28, and is utilized to suppress the scattering of burrs. Therefore, compared to, for example, using a dedicated component for suppressing the scattering of burrs, it is possible to suppress an increase in the number of components and assembly labor, and ultimately to suppress an increase in costs.

[0030] Second Embodiment Next, a second embodiment of the technique of the present disclosure will be described.

[0031] In the second embodiment, the configuration of the rotor 12 is changed as follows from the first embodiment. The following describes the second embodiment, focusing on the differences from the first embodiment.

[0032] As shown in Fig. 4, the first cover 20 has a recess 36 that opens toward the first axial end face 24 (i.e., the side indicated by arrow B). The recess 36 is formed in an annular shape around the opening 26A of the press-fit hole 26 on the first axial end face 24 side. The recess 36 is formed, for example, when the first cover 20 is formed by punching. The space 32 is formed by being surrounded by the first axial end face 24 and the recess 36. The space 32 is formed in an annular shape around the opening 26A of the press-fit hole 26 on the first axial end face 24 side.

[0033] Even with this configuration, if burrs are generated from the rotor core 16 when the shaft 14 is pressed into the press-fit hole 26 during the shaft press-fitting process, the burrs can be contained within the space 32, thereby preventing the burrs from scattering.

[0034] Furthermore, the first cover 20 has a recess 36 that opens to the side of the first axial end face 24, and the space 32 is formed by being surrounded by the first axial end face 24 and the recess 36. Therefore, with the simple structure of forming the recess 36 in the first cover 20, the space 32 for trapping burrs can be formed.

[0035] Furthermore, since the first cover 20 is made of metal, the recess 36 can be easily formed at low cost.

[0036] Third Embodiment Next, a third embodiment of the technique of the present disclosure will be described.

[0037] In the third embodiment, the configuration of the rotor 12 is changed as follows from the first embodiment. The following describes the third embodiment, focusing on the differences from the first embodiment.

[0038] As shown in FIG. 5 , the first cover 20 has a burred portion 38 formed by burring. The burred portion 38 extends on the opposite side from the first axial end face 24 (i.e., the side indicated by arrow A). The burred portion 38 is cylindrically formed around the opening 26A of the press-fit hole 26 on the first axial end face 24 side. The burred portion 38 has a curved portion 38A and a tubular portion 38B. The space 32 is formed by being surrounded by the first axial end face 24 and the burred portion 38. The space 32 is annularly formed around the opening 26A of the press-fit hole 26 on the first axial end face 24 side.

[0039] Even with this configuration, if burrs are generated from the rotor core 16 when the shaft 14 is pressed into the press-fit hole 26 during the shaft press-fitting process, the burrs can be contained within the space 32, thereby preventing the burrs from scattering.

[0040] Furthermore, the first cover 20 has a burred portion 38 formed by burring and extending on the side opposite to the first axial end face 24, and the space 32 is formed by being surrounded by the first axial end face 24 and the burred portion 38. Therefore, with the simple structure of forming the burred portion 38 on the first cover 20, the space 32 for containing burrs can be formed.

[0041] Furthermore, since the first cover 20 is made of metal, the burred portion 38 can be easily formed at low cost.

[0042] Fourth Embodiment Next, a fourth embodiment of the technique of the present disclosure will be described.

[0043] In the fourth embodiment, the configuration of the rotor 12 is changed as follows compared to the first embodiment. The following describes the fourth embodiment, focusing on the differences from the first embodiment.

[0044] As shown in FIG. 6, the plurality of core sheets 22 forming the rotor core 16, which is a laminate, include a plurality of first core sheets 22A and second core sheets 22B.

[0045] The plurality of first core sheets 22A are those of the plurality of core sheets 22 that are located on the first cover 20 side. The second core sheets 22B are those of the remaining core sheets 22 excluding the plurality of first core sheets 22A that are located on the first core sheet 22A side. The plurality of first core sheets 22A are located between the first cover 20 and the second core sheets 22B. The press-fit hole 26 is formed by the remaining core sheets 22 of the plurality of core sheets 22 excluding the plurality of first core sheets 22A.

[0046] In the fourth embodiment, the number of first core sheets 22A located between the first cover 20 and the second core sheet 22B is, for example, three, but may be any number. Alternatively, one first core sheet 22A may be located between the first cover 20 and the second core sheet 22B. The inner diameter D1 of each first core sheet 22A is the same. The inner diameter D1 of each first core sheet 22A is larger than the inner diameter D2 of the second core sheet 22B.

[0047] As shown in FIG. 7 , the plurality of first core sheets 22A and the second core sheets 22B form a first axial end surface 24. Specifically, the first cover 20-side surface of the plurality of first core sheets 22A located on the first cover 20 side forms an outer region 24A that is a region of the first axial end surface 24 radially outward from the inner diameter of the second core sheet 22B. The first core sheet 22A-side surface of the second core sheet 22B forms an inner region 24B that is a region radially inward from the inner diameter of the first core sheet 22A, which is a region of the first axial end surface 24 radially inward from the outer region 24A. Furthermore, the inner circumferential surfaces of the plurality of first core sheets 22A form an intermediate region 24C that is a region of the first axial end surface 24 between the inner region 24B and the outer region 24A. In this way, the first axial end surface 24 is formed across a plurality of first core sheets 22A and second core sheets 22B, and has an inner region 24B, an outer region 24A, and a middle region 24C.

[0048] The space 32 is formed by being surrounded by the multiple first core sheets 22A, the second core sheets 22B, and the first cover 20. Specifically, the space 32 is formed by being surrounded by an inner region 24B of the first axial end face 24, an intermediate region 24C of the first axial end face 24, and a portion 20A of the first cover 20 that is radially inward of the outer region 24A. The space 32 is formed in an annular shape around the opening 26A of the press-fit hole 26 on the first axial end face 24 side. The space 32 is formed by the difference between the inner diameter D1 of each first core sheet 22A and the inner diameter D2 of the second core sheet 22B. The portion 20A of the first cover 20 that is radially inward of the outer region 24A is formed flat.

[0049] Even with this configuration, if burrs are generated from the rotor core 16 when the shaft 14 is pressed into the press-fit hole 26 during the shaft press-fitting process, the burrs can be contained within the space 32, thereby preventing the burrs from scattering.

[0050] The core sheets 22 include a plurality of first core sheets 22A and second core sheets 22B, and the space 32 is formed by the difference between the inner diameter D1 of each first core sheet 22A and the inner diameter D2 of each second core sheet 22B. Therefore, with the simple structure of making the inner diameter D1 of each first core sheet 22A different from the inner diameter D2 of the second core sheet 22B, the space 32 for trapping burrs can be formed.

[0051] In the above-described embodiments, the first cover 20 is made of metal, but it may be made of resin.

[0052] Furthermore, when the first cover 20 is made of resin, the inner circumferential surface of the first cover 20 may be in close contact with the outer circumferential surface of the shaft 14 .

[0053] Furthermore, although the first cover 20 covers the plurality of receiving holes 28 , it may be a cover separate from the cover that covers the plurality of receiving holes 28 .

[0054] The above describes the first to fourth embodiments of the technology of the present disclosure, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modifications within the scope of the gist of the present disclosure.

[0055] The following are supplementary notes regarding the technology of the present disclosure. (Supplementary Note 1) A rotor (12) comprising: a rotor core (16) having a press-fit hole (26) into which a shaft (14) is press-fit; and a cover (20) covering an axial end face (24) of the rotor core, wherein a space (32) surrounded by the axial end face and the cover is formed around an opening (26A) of the press-fit hole on the axial end face side. (Supplementary Note 2) The rotor according to Supplementary Note 1, wherein the cover has a loose insertion hole (30) into which the shaft is loosely inserted, and is made of metal. (Supplementary Note 3) The rotor according to Supplementary Note 1 or Supplementary Note 2, wherein the rotor core has: a plurality of accommodating holes (28) opening into the axial end face; and a plurality of magnets (18) respectively accommodated in the plurality of accommodating holes, wherein the cover closes the plurality of accommodating holes. (Supplementary Note 4) The rotor according to any one of Supplementary Notes 1 to 3, wherein the cover is formed by drawing and has a drawn portion (34) that is convex on a side opposite to the axial end face, and the space is formed by being enclosed by the axial end face and the drawn portion. (Supplementary Note 5) The rotor according to any one of Supplementary Notes 1 to 3, wherein the cover has a recess (36) that opens to the axial end face side, and the space is formed by being enclosed by the axial end face and the recess. (Supplementary Note 6) The rotor according to any one of Supplementary Notes 1 to 3, wherein the cover is formed by burring and has a burred portion (38) that extends on a side opposite to the axial end face, and the space is formed by being enclosed by the axial end face and the burred portion. (Appendix 7) The rotor according to any one of Appendices 1 to 3, wherein the rotor core is a laminate formed by stacking a plurality of core sheets (22), the plurality of core sheets include a first core sheet (22A) and a second core sheet (22B) that form the axial end faces, the first core sheet is located between the cover and the second core sheet, the inner diameter of the first core sheet is larger than the inner diameter of the second core sheet, and the space is formed by the difference between the inner diameter of the first core sheet and the inner diameter of the second core sheet.(Appendix 8) A method for manufacturing a rotor-shaft assembly (10) having a rotor and a shaft, comprising: a cover mounting step of attaching a cover that covers an axial end face of a rotor core of the rotor to the rotor core, and forming a space surrounded by the axial end face and the cover around an opening on the axial end face side of a press-fit hole of the rotor core; and a shaft press-fitting step of press-fitting the shaft into the press-fit hole and confining burrs generated from the rotor core during press-fitting within the space.

Claims

1. A rotor (12) comprising: a rotor core (16) having a press-fit hole (26) into which a shaft (14) is press-fit; and a cover (20) covering an axial end face (24) of the rotor core, wherein a space (32) surrounded by the axial end face and the cover is formed around an opening (26A) on the axial end face side of the press-fit hole.

2. A rotor according to claim 1, wherein the cover has a loose insertion hole (30) into which the shaft is loosely inserted, and is made of metal.

3. A rotor as set forth in claim 1 or claim 2, wherein the rotor core has a plurality of accommodating holes (28) opening to the axial end face, and a plurality of magnets (18) accommodated in the plurality of accommodating holes, respectively, and the cover closes the plurality of accommodating holes.

4. A rotor as set forth in any one of claims 1 to 3, wherein the cover is formed by drawing and has a convex drawn portion (34) on the side opposite to the axial end face, and the space is formed by being enclosed by the axial end face and the drawn portion.

5. A rotor as set forth in any one of claims 1 to 3, wherein the cover has a recess (36) that opens to the side of the axial end face, and the space is formed by being enclosed by the axial end face and the recess.

6. A rotor as set forth in any one of claims 1 to 3, wherein the cover is formed by burring and has a burred portion (38) extending on the side opposite to the axial end face, and the space is formed by being enclosed by the axial end face and the burred portion.

7. A rotor as set forth in any one of claims 1 to 3, wherein the rotor core is a laminate formed by stacking a plurality of core sheets (22), the plurality of core sheets including a first core sheet (22A) and a second core sheet (22B) that form the axial end faces, the first core sheet is located between the cover and the second core sheet, the inner diameter of the first core sheet is larger than the inner diameter of the second core sheet, and the space is formed by the difference between the inner diameter of the first core sheet and the inner diameter of the second core sheet.

8. A method for manufacturing a rotor-shaft assembly (10) having a rotor and a shaft, comprising: a cover mounting step of attaching a cover that covers the axial end face of a rotor core of the rotor to the rotor core, and forming a space surrounded by the axial end face and the cover around the opening of a press-fit hole in the rotor core on the axial end face side; and a shaft press-fitting step of press-fitting the shaft into the press-fit hole and confining burrs generated from the rotor core during press-fitting within the space.

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