Rotating electric machine

Abstract

To provide a rotary electric machine capable of suppressing a drop in axial force of a fastening member.SOLUTION: A rotary electric machine 10 includes a stator 12, a vanish 29 provided on the stator 12, and a pair of end brackets 14, 15. The stator 12 has a cylindrical stator core 21 in which a plurality of disc-like electromagnetic steel plates 30 are laminated. The pair of end brackets 14, 15 are arranged at both sides of the stator 12, and also restrain the stator core 21 in an axial direction by being fastened to each other by a stud bolt and a nut N. The stator core 21 includes a welded part 25 at which outer peripheral surfaces of the plurality of electromagnetic steel plates 30 are welded, and a first outer peripheral part 27 being an outer peripheral part of the stator core 21 and being a part with the welded part 25 provided. A gap between the electromagnetic steel plates 30 in the first outer peripheral part 27 is smaller than a gap between the electromagnetic steel plates 30 in other parts. The pair of end brackets 14, 15 give a binding load to the first outer peripheral part 27.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating electric machine.

Background Art

[0002] Patent Document 1 discloses a motor including a stator and a housing. The stator has a cylindrical stator core and a coil wound around the stator core. The stator core is formed by laminating a plurality of disk-shaped electromagnetic steel sheets. A varnish for fixing the coil and the stator core is applied to the coil. The stator is fixed to the housing by bolts.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The varnish may penetrate between the electromagnetic steel sheets. In this case, when the motor becomes hot during operation, the varnish that has penetrated between the electromagnetic steel sheets may creep, resulting in a possible decrease in the axial force of the bolts.

Means for Solving the Problems

[0005] The rotating electric machine for solving the above problems comprises a stator having a cylindrical stator core formed by stacking multiple disc-shaped electromagnetic steel sheets, a resin coating applied to the stator, and a pair of end brackets positioned on both sides of the stator in the axial direction of the stator core and fastened to each other by fastening members to restrain the stator core in the axial direction. The stator core has a welded portion where the outer surfaces of the multiple electromagnetic steel sheets are welded together, and a first outer peripheral portion which is the outer peripheral portion of the stator core where the welded portion is provided. The gap between the electromagnetic steel sheets in the first outer peripheral portion is smaller than the gap between the electromagnetic steel sheets in other portions, and the pair of end brackets apply a restraining load to the first outer peripheral portion.

[0006] The gaps between the electrical steel sheets in the first outer periphery are smaller than the gaps between the electrical steel sheets in other parts. Therefore, in the first outer periphery, the amount of resin paint that penetrates between the electrical steel sheets is small because it is difficult for the resin paint to penetrate between the electrical steel sheets. Consequently, when the pair of end brackets restrain the stator core, by applying a restraining load to the first outer periphery where the amount of resin paint that penetrates is small, it is possible to suppress the decrease in the axial force of the fastening members when the resin paint that has penetrated between the electrical steel sheets creeps.

[0007] In the above-described rotating electric machine, each of the pair of end brackets is a bottomed cylindrical shape having an end wall and a cylindrical peripheral wall erected from the peripheral edge of the end wall, and both ends of the stator in the axial direction of the stator core are housed within the pair of end brackets, and the peripheral wall has a contact surface on its inner circumference that is recessed from the tip surface of the peripheral wall, and the contact surface may be in contact with the first outer circumference.

[0008] One possible method to suppress the reduction in axial force of the fastening members is to apply a coating layer to the surface of the stator core, and then apply a resin coating on top of the coating layer. In this case, the presence of the coating layer makes it difficult for the resin coating to penetrate between the electrical steel sheets, thus suppressing the reduction in axial force of the fastening members due to creep of the resin coating that has penetrated between the electrical steel sheets. However, this method requires the addition of new materials or processes to make it difficult for the resin coating to penetrate between the electrical steel sheets. In contrast, in the above configuration, the pair of end brackets apply a restraining load directly to the first outer circumference of the stator core by having their contact surfaces abut against the first outer circumference. In this case, the reduction in axial force of the fastening members can be suppressed without adding materials or processes to make it difficult for the resin coating to penetrate between the electrical steel sheets.

[0009] In the above-described rotating electric machine, an intervening member may be positioned between the first outer periphery of the stator core and the end bracket in the axial direction of the stator core, and the pair of end brackets may apply a restraining load to the first outer periphery via the intervening member.

[0010] A pair of end brackets apply a restraining load to the first outer circumference of the stator core via an intervening member, which is a separate component from the end brackets. Therefore, if the number or position of welds on the stator core changes, this can be accommodated by changing only the number or arrangement of the intervening members, without changing the shape of the end brackets. Consequently, the same shape of end brackets can be used for multiple types of stator cores with different numbers and positions of welds.

[0011] In the above-described rotating electric machine, each of the plurality of electromagnetic steel sheets has a bent portion bent in the thickness direction, and the bent portion has a convex portion protruding from the first surface of the electromagnetic steel sheet and a concave portion recessed in the second surface which is the surface opposite to the first surface of the electromagnetic steel sheet, and the stator core has an engagement portion in which the plurality of electromagnetic steel sheets are engaged in a concave-convex-convex manner by the convex portion of the electromagnetic steel sheet engaging with the concave portion of the adjacent electromagnetic steel sheet, and the pair of end brackets do not need to apply a restraining load to the second outer periphery of the stator core which is the outer periphery of the stator core and is the portion where the engagement portion is provided.

[0012] Because the bending portion creates tension around the bend in the electrical steel sheet, the gap between the electrical steel sheets in the second outer circumference tends to be larger than the gap between the electrical steel sheets in other parts. Therefore, in the second outer circumference, the amount of resin coating that penetrates between the electrical steel sheets tends to be larger. Accordingly, when the pair of end brackets restrain the stator core, by not applying a restraining load to the second outer circumference where the amount of resin coating that penetrates is likely to be large, the decrease in the axial force of the fastening member when the resin coating that has penetrated between the electrical steel sheets creeps can be further suppressed.

[0013] In the above-described rotating electric machine, each of the pair of end brackets is a bottomed cylindrical shape having an end wall and a cylindrical peripheral wall erected from the peripheral edge of the end wall, and both ends of the stator in the axial direction of the stator core are housed within the pair of end brackets, and the peripheral wall has a contact surface on its inner circumference that is recessed from the tip surface of the peripheral wall, and the peripheral wall of at least one of the pair of end brackets further has a relief portion that is recessed from the contact surface, the contact surface may be in contact with the first outer circumference, and the relief portion may be facing the second outer circumference.

[0014] One possible method to suppress the reduction in the axial force of the fastening member is to pre-apply a coating layer to the surface of the stator core. In this case, the presence of the coating layer makes it difficult for the resin coating to penetrate between the electromagnetic steel sheets, thereby suppressing the reduction in the axial force of the fastening member. However, this requires the creation of new components or processes to prevent the resin coating from penetrating between the electromagnetic steel sheets. In contrast, with the above configuration, by devising the shape of the pair of end brackets that are components for restraining the stator core, the reduction in the axial force of the fastening member can be suppressed without creating new components or processes to prevent the resin coating from penetrating between the electromagnetic steel sheets.

[0015] Furthermore, by having the relief portion provided on the end bracket face the second outer circumference of the stator core, the pair of end brackets can be prevented from applying a restraining load to the second outer circumference of the stator core. As a configuration to prevent the pair of end brackets from applying a restraining load to the second outer circumference, for example, it is conceivable to provide a relief portion on the second outer circumference of the stator core that is recessed compared to the outer surface of the stator core. However, in this case, it is necessary to change the shape of both the end bracket and the stator core. In contrast, when a relief portion is provided on the end bracket, the pair of end brackets can apply a restraining load to the first outer circumference, but not to the second outer circumference, without changing the shape of the stator core.

[0016] In the above-described rotating electric machine, the second outer periphery may have a recessed portion that is recessed compared to the outer periphery of the stator core. Because the second outer circumference of the stator core has a recessed portion that is lower than the outer surface of the stator core, the pair of end brackets can be prevented from applying a restraining load to the second outer circumference of the stator core. In this case, even if the number or position of the engagement portions of the stator core is changed, this can be accommodated simply by changing the number or position of the relief portions of the stator core. Therefore, the same shape of end bracket can be used for multiple types of stator cores with different numbers and positions of engagement portions. [Effects of the Invention]

[0017] According to the present invention, it is possible to reduce the reduction in the axial force of the fastening member.

Brief Description of the Drawings

[0018] [Figure 1] It is a side sectional view showing a rotating electric machine in an embodiment. [Figure 2] It is an exploded perspective view showing a stator and a pair of end brackets in an embodiment. [Figure 3] It is a front view showing a stator core in an embodiment. [Figure 4] It is a sectional view taken along line 4-4 in FIG. 3. [Figure 5] It is a front view showing a first end bracket in an embodiment. [Figure 6] It is a front view showing a stator core and a first end bracket in an embodiment. [Figure 7] It is a side sectional view showing a rotating electric machine in an embodiment. [Figure 8] It is a side sectional view showing a rotating electric machine in a modified example. [Figure 9] It is a front view showing a first end bracket in a modified example. [Figure 10] It is a front view showing a stator core and a first end bracket in a modified example.

Mode for Carrying Out the Invention

[0019] Hereinafter, an embodiment in which a rotating electric machine is embodied will be described according to FIGS. 1 to 7. As shown in FIG. 1, the rotating electric machine 10 includes a rotating shaft 11, a stator 12, a rotor 13, and a pair of end brackets 14 and 15.

[0020] <Stator> As shown in Figures 1 and 2, the stator 12 has a cylindrical stator core 21 and a coil 22 wound around the stator core 21. The stator core 21 has a plurality of electromagnetic steel sheets 30.

[0021] As shown in Figure 3, the stator core 21 has a cylindrical yoke 23 and a plurality of teeth 24. The teeth 24 extend radially inward from the yoke 23. The plurality of teeth 24 are arranged at equal intervals in the circumferential direction of the yoke 23. The coil 22 is wound around the teeth 24. Note that the coil 22 is shown in a simplified form in Figures 1 and 2.

[0022] The electromagnetic steel sheet 30 is disc-shaped. The electromagnetic steel sheet 30 has a disc-shaped yoke component 31 and a plurality of tooth components 32. The tooth components 32 extend radially inward from the yoke component 31. The plurality of tooth components 32 are arranged at equal intervals in the circumferential direction of the yoke component 31.

[0023] The electromagnetic steel sheet 30 has a plurality of weldable portions 33. In this embodiment, the electromagnetic steel sheet 30 has eight weldable portions 33. The weldable portions 33 are recessed portions from the outer surface of the electromagnetic steel sheet 30. The plurality of weldable portions 33 are arranged at equal intervals in the circumferential direction of the electromagnetic steel sheet 30.

[0024] The electromagnetic steel sheet 30 has a plurality of bent portions 34. The electromagnetic steel sheet 30 in this embodiment has eight bent portions 34. The plurality of bent portions 34 are arranged at equal intervals in the circumferential direction of the electromagnetic steel sheet 30. The welded portions 33 and the bent portions 34 are arranged alternately in the circumferential direction of the electromagnetic steel sheet 30. The bent portions 34 are provided in the yoke component 31. The bent portions 34 are located inward from the welded portions 33 in the radial direction of the electromagnetic steel sheet 30.

[0025] As shown in Figure 4, the electrical steel sheet 30 has a first surface 30a and a second surface 30b. The first surface 30a and the second surface 30b are surfaces perpendicular to the thickness direction of the electrical steel sheet 30. The second surface 30b is the surface located opposite the first surface 30a in the thickness direction of the electrical steel sheet 30. The bent portion 34 is formed by bending the electrical steel sheet 30 from the second surface 30b toward the first surface 30a. The bent portion 34 has a convex portion 34a that protrudes from the first surface 30a of the electrical steel sheet 30 and a concave portion 34b that is recessed compared to the second surface 30b of the electrical steel sheet 30.

[0026] Of the multiple electromagnetic steel sheets 30, one electromagnetic steel sheet 30 has multiple through holes 35 that penetrate the electromagnetic steel sheet 30 in the thickness direction instead of a bent portion 34. In this embodiment, the electromagnetic steel sheet 30 has eight through holes 35. The multiple through holes 35 are arranged at equal intervals in the circumferential direction of the electromagnetic steel sheet 30. The welded portion 33 and the through holes 35 are arranged alternately in the circumferential direction of the electromagnetic steel sheet 30. The through holes 35 are provided in the yoke component 31. The through holes 35 are located inside the welded portion 33 in the radial direction of the electromagnetic steel sheet 30.

[0027] As shown in Figure 1, the stator core 21 is formed by laminating multiple electromagnetic steel sheets 30. The yoke 23 is formed by laminating yoke components 31 of multiple electromagnetic steel sheets 30. The teeth 24 are formed by laminating tooth components 32 of multiple electromagnetic steel sheets 30. The lamination direction of the electromagnetic steel sheets 30 coincides with the axial direction of the stator core 21. An electromagnetic steel sheet 30 having a through hole 35 is arranged at one end in the lamination direction. The outer circumferential surface of the stator core 21 is formed by the outer circumferential surfaces of multiple electromagnetic steel sheets 30.

[0028] As shown in Figure 2, the welded portions 33 of the multiple electromagnetic steel sheets 30 are aligned in the stacking direction. The multiple electromagnetic steel sheets 30 are fixed to each other by welding the welded portions 33 together while under pressure and compression in the stacking direction. The stator core 21 has multiple welded portions 25 in the circumferential direction, formed by welding the outer surfaces of the multiple electromagnetic steel sheets 30 together. The multiple welded portions 25 are provided at equal intervals in the circumferential direction of the stator core 21.

[0029] As shown in Figure 4, the bent portions 34 of the multiple electromagnetic steel sheets 30 are aligned in the stacking direction. The convex portion 34a of the bent portion 34 of the electromagnetic steel sheet 30 is engaged with the concave portion 34b of the bent portion 34 of the adjacent electromagnetic steel sheet 30 in the stacking direction. The convex portion 34a of the bent portion 34 of the adjacent electromagnetic steel sheet 30 is inserted into the through hole 35 of the electromagnetic steel sheet 30 located at one end in the stacking direction.

[0030] As shown in Figure 3, the stator core 21 has multiple engagement portions 26 in the circumferential direction, where multiple electromagnetic steel sheets 30 are interlocked in a grooved manner. The multiple engagement portions 26 are provided at equal intervals in the circumferential direction of the stator core 21. The welded portions 25 and the engagement portions 26 are provided alternately in the circumferential direction of the stator core 21. The engagement portions 26 are located inward of the welded portions 25 in the radial direction of the stator core 21.

[0031] The stator core 21 has a plurality of first outer peripheral portions 27 and a plurality of second outer peripheral portions 28. The first outer peripheral portions 27 and the second outer peripheral portions 28 are each the outer peripheral portion of the stator core 21. The outer peripheral portion of the stator core 21 is the portion located radially outward from the coil 22 on the stator core 21, i.e., the yoke 23. The outer peripheral surface of the yoke 23, which is the outer peripheral surface of the stator core 21, is part of the outer peripheral portion of the stator core 21. The first outer peripheral portions 27 are the portions on the outer peripheral portion of the stator core 21 where welded portions 25 are provided. The second outer peripheral portions 28 are the portions on the outer peripheral portion of the stator core 21 where engaging portions 26 are provided. The first outer peripheral portions 27 and the second outer peripheral portions 28 are alternately located in the circumferential direction of the stator core 21.

[0032] In the drawing, the axial thickness of the stator core 21 is shown to be the same around its entire circumference, but in reality, the axial thickness of the stator core 21 is slightly different in the circumferential direction.

[0033] As described above, multiple electromagnetic steel sheets 30 are welded together under pressure and compression. As a result, even after the pressure and compression are released in the first outer periphery 27, the welded joints 25 keep the electromagnetic steel sheets 30 close to each other. Therefore, the gaps between the electromagnetic steel sheets 30 in the first outer periphery 27 are smaller than the gaps between the electromagnetic steel sheets 30 in other parts. Here, "small gaps between the electromagnetic steel sheets 30 in the first outer periphery 27" includes cases where there are no gaps between the electromagnetic steel sheets 30, such as when the electromagnetic steel sheets 30 are in contact with each other or when the electromagnetic steel sheets 30 are connected by the welded joints 25.

[0034] Furthermore, since the size of the gaps between the electromagnetic steel sheets 30 varies from gap to gap, it is not necessarily the case that all the gaps between the electromagnetic steel sheets 30 in the first outer periphery 27 are smaller than the gaps between the electromagnetic steel sheets 30 in other parts. However, when considering the average size of multiple gaps rather than the size of each individual gap, the gaps between the electromagnetic steel sheets 30 in the first outer periphery 27 are smaller than the gaps between the electromagnetic steel sheets 30 in other parts. Therefore, the axial thickness of the stator core 21 in the first outer periphery 27 is thinner than the thickness of the stator core 21 in other parts of the outer periphery of the stator core 21.

[0035] In contrast, in areas other than the first outer periphery 27, when the pressure and compression are released after welding, the electromagnetic steel sheets 30 return to their original state from being close together, thus increasing the gaps between the electromagnetic steel sheets 30. In particular, because the bending portion 34 creates tension around the bending portion 34 in the electromagnetic steel sheet 30, the gaps between the electromagnetic steel sheets 30 tend to be larger in the second outer periphery 28. Consequently, the axial thickness of the stator core 21 in the second outer periphery 28 is thicker than the thickness of the stator core 21 in other parts of the outer periphery of the stator core 21.

[0036] In this embodiment, the axial thickness of the stator core 21 gradually increases in the circumferential direction from the first outer periphery 27 to the second outer periphery 28. In this embodiment, the difference between the axial thickness of the stator core 21 at the first outer periphery 27 and the axial thickness of the stator core 21 at the second outer periphery 28 is several hundred microns.

[0037] As shown in Figures 1 and 2, the stator 12 is provided with varnish 29 as a resin coating. In this embodiment, the varnish 29 is provided on the outer circumferential surface of the stator core 21. The varnish 29 in this embodiment is a rust-preventive varnish to suppress the occurrence of rust on the stator core 21. The varnish 29 is provided on the outer circumferential surface of the stator core 21 by being applied to the outer circumferential surface of the stator core 21 and then drying. When the varnish 29 is applied to the outer circumferential surface of the stator core 21, it is considered that the varnish 29 penetrates between the electromagnetic steel sheets 30 from the outer circumferential surface of the stator core 21. Therefore, among the gaps between the electromagnetic steel sheets 30 in the first outer circumferential portion 27, it is preferable that the gap between the electromagnetic steel sheets 30 on the outer circumferential surface of the stator core 21 be as small as possible. The smaller the gap between the electromagnetic steel sheets 30 on the outer circumferential surface of the stator core 21, the less likely the varnish 29 applied to the outer circumferential surface of the stator core 21 is to penetrate between the electromagnetic steel sheets 30.

[0038] As shown in Figure 1, a cylindrical rotor 13 is positioned inside the stator 12. The rotating shaft 11 is inserted through the rotor 13 and fixed to it. The rotating shaft 11 rotates integrally with the rotor 13.

[0039] In the following explanation, of the pair of end brackets 14 and 15, one end bracket 14 will be referred to as the first end bracket 14, and the other end bracket 15 will be referred to as the second end bracket 15.

[0040] As shown in Figures 2 and 5, the first end bracket 14 is a bottomed cylindrical shape having a first end wall 41 as an end wall and a first circumferential wall 42 as a cylindrical circumferential wall extending from the peripheral edge of the first end wall 41 in the thickness direction of the first end wall 41. The first end bracket 14 has a first axial hole 41a that penetrates the first end wall 41 in the thickness direction. The first end bracket 14 has a plurality of first bolt holes 42a that penetrate the first circumferential wall 42. The first end bracket 14 in this embodiment has four first bolt holes 42a. The direction in which the first bolt holes 42a extend coincides with the direction in which the first circumferential wall 42 extends from the first end wall 41. An opening 42b is provided in the middle of the circumferential direction of the first circumferential wall 42.

[0041] As shown in Figures 1 and 5, the first circumferential wall 42 has multiple first contact surfaces 43 on its inner circumference, which serve as abutment surfaces. The first contact surfaces 43 are recessed surfaces compared to the tip surface 421 of the first circumferential wall 42. The width of the first contact surfaces 43 in the circumferential direction of the first circumferential wall 42 is greater than the width of the first outer circumference 27 of the stator core 21 in the circumferential direction. The first circumferential wall 42 also has multiple relief portions 44 on its inner circumference. The relief portions 44 are recessed portions compared to the first contact surfaces 43. The width of the relief portions 44 in the circumferential direction of the first circumferential wall 42 is greater than the width of the second outer circumference 28 of the stator core 21 in the circumferential direction. The first contact surfaces 43 and relief portions 44 are arranged alternately in the circumferential direction of the first circumferential wall 42. In this embodiment, the depth from the first contact surface 43 to the bottom surface of the relief portion 44 is greater than the difference between the axial thickness of the stator core 21 in the first outer peripheral portion 27 and the axial thickness of the stator core 21 in the second outer peripheral portion 28.

[0042] As shown in Figure 2, the second end bracket 15 is a bottomed cylindrical shape having a second end wall 51 as an end wall and a second peripheral wall 52 as a cylindrical peripheral wall extending from the peripheral edge of the second end wall 51 in the thickness direction of the second end wall 51. The second end bracket 15 has a second shaft hole 51a that penetrates the second end wall 51 in the thickness direction. The second end bracket 15 has a plurality of second bolt holes 52a provided in the second peripheral wall 52. The second end bracket 15 of this embodiment has four second bolt holes 52a. Female threads are formed on the inner peripheral surface that partitions the second bolt holes 52a. The second bolt holes 52a open at the tip surface 521 of the second peripheral wall 52. The second peripheral wall 52 has a second contact surface 53 on its inner circumference that is recessed from the tip surface 521 of the second peripheral wall 52. The second contact surface 53 is provided around the entire circumference of the second peripheral wall 52.

[0043] As shown in Figure 1, one end of the stator 12 in the axial direction of the stator core 21 is housed in the first end bracket 14, and the other end of the stator 12 in the axial direction of the stator core 21 is housed in the second end bracket 15. Specifically, the first end wall 41 of the first end bracket 14 and the second end wall 51 of the second end bracket 15 are located on both sides of the stator 12 in the axial direction of the stator core 21. The first circumferential wall 42 of the first end bracket 14 is located on the outer circumference of the coil 22 at one end of the stator core 21 in the axial direction, and the second circumferential wall 52 of the second end bracket 15 is located on the outer circumference of the coil 22 at the other end of the stator core 21 in the axial direction.

[0044] As shown in Figure 6, the stator core 21 is positioned such that its first outer circumference 27 corresponds to the first contact surface 43 and its second outer circumference 28 corresponds to the relief portion 44 with respect to the first end bracket 14. The first outer circumference 27 of the stator core 21 is positioned to overlap the first contact surface 43 of the first end bracket 14 in the axial direction of the stator core 21. The second outer circumference 28 of the stator core 21 is positioned to overlap the relief portion 44 of the first end bracket 14 in the axial direction of the stator core 21.

[0045] As shown in Figure 1, the first outer peripheral portion 27 of the stator core 21 is located between the first contact surface 43 and the second contact surface 53 in the axial direction of the stator core 21. The first outer peripheral portion 27 abuts against the first contact surface 43 at one end in the axial direction of the stator core 21, and abuts against the second contact surface 53 at the other end in the axial direction of the stator core 21.

[0046] As shown in Figure 7, the second outer periphery 28 of the stator core 21 is located between the bottom surface of the relief portion 44 and the second contact surface 53 in the axial direction of the stator core 21. The second outer periphery 28 faces the bottom surface of the relief portion 44. In this embodiment, there is a gap between the bottom surface of the relief portion 44 and the second outer periphery 28. The second outer periphery 28 is in contact with the second contact surface 53 of the second end bracket 15.

[0047] As shown in Figure 2, the first end bracket 14 and the second end bracket 15 are fastened together by a stud bolt B and a nut N, which are fastening members. Specifically, the stud bolt B is inserted through the first bolt hole 42a of the first end bracket 14 and then screwed into the second bolt hole 52a of the second end bracket 15. A washer W is then inserted through the portion of the stud bolt B that protrudes from the first end wall 41 of the first end bracket 14, and then a nut N is screwed onto it. The first end bracket 14 and the second end bracket 15 are fastened together by the axial force of the fastening members. The first end bracket 14 and the second end bracket 15 are fastened together by the fastening members, thereby restraining the stator core 21 in the axial direction.

[0048] As shown in Figure 1, the first end bracket 14 and the second end bracket 15 apply a restraining load to the first outer circumference 27 of the stator core 21. In this embodiment, the first end bracket 14 and the second end bracket 15 apply a restraining load directly to the first outer circumference 27 of the stator core 21 by having their first contact surface 43 and second contact surface 53 contact the first outer circumference 27 of the stator core 21. Therefore, the axial force of the fastening members acts on the first outer circumference 27 of the stator core 21 via the first end bracket 14 and the second end bracket 15.

[0049] On the other hand, as shown in Figure 7, the first end bracket 14 and the second end bracket 15 do not apply a restraining load to the second outer circumference 28 of the stator core 21. Therefore, the axial force of the fastening members does not act on the second outer circumference 28 of the stator core 21.

[0050] In other words, the first end bracket 14 and the second end bracket 15 restrain the stator core 21 in the axial direction by applying a restraining load to the first outer circumference 27 of the stator core 21.

[0051] As shown in Figure 1, the first end of the rotating shaft 11 is inserted through the first shaft hole 41a. The first end of the rotating shaft 11 is rotatably supported by the first end bracket 14 via the first bearing 16. The second end of the rotating shaft 11, which is the end opposite to the first end, is inserted through the second shaft hole 51a. The second end of the rotating shaft 11 is rotatably supported by the second end bracket 15 via the second bearing 17.

[0052] [Operation and Effects of This Embodiment] The operation and effects of this embodiment will now be explained. (1) The stator core 21 is formed by laminating a plurality of electromagnetic steel sheets 30. The stator core 21 has welded sections 25 where the outer surfaces of the plurality of electromagnetic steel sheets 30 are welded together. The stator core 21 has a first outer peripheral section 27, which is the outer peripheral section of the stator core 21 where the welded sections 25 are provided. The gaps between the electromagnetic steel sheets 30 in the first outer peripheral section 27 are smaller than the gaps between the electromagnetic steel sheets 30 in other sections. Therefore, in the first outer peripheral section 27, the amount of varnish 29 that penetrates between the electromagnetic steel sheets 30 is small because the varnish 29 is less likely to penetrate between the electromagnetic steel sheets 30. Accordingly, when the pair of end brackets 14 and 15 restrain the stator core 21, they apply a restraining load to the first outer peripheral section 27 where the amount of varnish 29 that penetrates is small. This makes it possible to suppress the decrease in the axial force of the fastening members when the varnish 29 that has penetrated between the electromagnetic steel sheets 30 creeps.

[0053] (2) As methods to suppress the decrease in axial force of fastening members, for example, the following first to third methods can be considered. In the first method, a coating layer is formed on the surface of the stator core 21 before applying the varnish 29 to the stator 12. In this case, the presence of the coating layer makes it difficult for the varnish 29 to penetrate between the electrical steel sheets 30, thereby suppressing the decrease in the axial force of the fastening member when the varnish 29 that has penetrated between the electrical steel sheets 30 creeps. However, this method requires new components and processes to make it difficult for the varnish 29 to penetrate between the electrical steel sheets 30.

[0054] The second method involves fastening a pair of end brackets 14 and 15 with a fastening member, and then forcibly creeping the varnish 29 that has penetrated between the electromagnetic steel sheets 30. Then, the fastening member is tightened again. In this case, since the pair of end brackets 14 and 15 are fastened after the varnish 29 has creeped, the decrease in the axial force of the fastening member is suppressed. However, this method requires an aging process to forcibly creep the varnish 29.

[0055] A third method involves applying varnish 29 to the stator core 21 in areas where the axial force of the fastening member does not act, and not applying varnish 29 in areas where the axial force acts. Then, after fastening the pair of end brackets 14 and 15 with the fastening member, that is, while the axial force of the fastening member is acting on the stator core 21, varnish 29 is applied to the areas where it has not been applied. In this case, in the areas of the stator core 21 where the axial force of the fastening member acts, the varnish 29 is less likely to penetrate between the electromagnetic steel sheets 30, thus suppressing the decrease in the axial force of the fastening member. However, this method complicates the first application process and requires a second application process.

[0056] In contrast, in this embodiment, the first end bracket 14 is a bottomed cylindrical shape having a first end wall 41 and a cylindrical first circumferential wall 42 erected from the periphery of the first end wall 41. The second end bracket 15 is a bottomed cylindrical shape having a second end wall 51 and a cylindrical second circumferential wall 52 erected from the periphery of the second end wall 51. Both ends of the stator 12 in the axial direction of the stator core 21 are housed within the pair of end brackets 14 and 15. The first circumferential wall 42 has a first contact surface 43 on its inner circumference that is recessed from the tip surface 421 of the first circumferential wall 42. The second circumferential wall 52 has a second contact surface 53 on its inner circumference that is recessed from the tip surface 521 of the second circumferential wall 52. The pair of end brackets 14 and 15 apply a restraining load to the first outer circumference 27 by having their first contact surface 43 and second contact surface 53 contact the first outer circumference 27. In this case, the reduction in the axial force of the fastening members is suppressed by devising the shape of the pair of end brackets 14 and 15, which are members for restraining the stator core 21. Therefore, as in the first method, there is no need to newly provide members and processes to make it difficult for the varnish 29 to penetrate between the electromagnetic steel sheets 30. Furthermore, it is possible to avoid increasing the number and complexity of processes as in the second and third methods.

[0057] (3) The stator core 21 has an engagement portion 26 in which multiple electromagnetic steel sheets 30 are engaged in a concave-concave arrangement, where the convex portion 34a of the bent portion 34 of the electromagnetic steel sheet 30 engages with the concave portion 34b of the bent portion 34 of the adjacent electromagnetic steel sheet 30. The stator core 21 has a second outer periphery 28, which is the outer periphery of the stator core 21 and is the portion where the engagement portion 26 is provided. Because the bent portion 34 creates tension around the bent portion 34 of the electromagnetic steel sheet 30, the gap between the electromagnetic steel sheets 30 in the second outer periphery 28 tends to be larger than the gap between the electromagnetic steel sheets 30 in other parts. For this reason, the amount of varnish 29 that penetrates between the electromagnetic steel sheets 30 tends to be large in the second outer periphery 28. Accordingly, when the pair of end brackets 14 and 15 restrain the stator core 21, they do not apply a restraining load to the second outer periphery 28, where the amount of varnish 29 that penetrates tends to be large. This makes it possible to further suppress the decrease in the axial force of the fastening member when the varnish 29 that has penetrated between the electromagnetic steel sheets 30 creeps.

[0058] (4) The first end bracket 14 has a relief portion 44 that is recessed from the first contact surface 43. The relief portion 44 faces the second outer circumference 28 of the stator core 21. This prevents the pair of end brackets 14 and 15 from applying a restraining load to the second outer circumference 28 of the stator core 21.

[0059] Furthermore, as a configuration in which the pair of end brackets 14 and 15 do not impose a restraining load on the second outer circumference 28, for example, a relief portion recessed from the outer surface of the stator core 21 can be provided on the second outer circumference 28 of the stator core 21. However, in this case, it is necessary to change the shape of both the first end bracket 14 and the stator core 21. In contrast, in this embodiment, a relief portion 44 is provided on the first end bracket 14. As a result, without changing the shape of the stator core 21, the pair of end brackets 14 and 15 can impose a restraining load on the first outer circumference 27 of the stator core 21, but not on the second outer circumference 28.

[0060] (5) The pair of end brackets 14 and 15 directly apply a restraining load to the first outer circumference 27 of the stator core 21. Therefore, compared to the case where the pair of end brackets 14 and 15 indirectly apply a restraining load to the first outer circumference 27 via other members, a restraining load can be stably applied to the first outer circumference 27.

[0061] (6) Since the pair of end brackets 14 and 15 are fastened to each other by multiple fastening members, they are less prone to misalignment. Therefore, it is possible to suppress misalignment in the position where the pair of end brackets 14 and 15 apply a restraining load to the stator core 21.

[0062] (7) The stator core 21 is restrained by a pair of end brackets 14 and 15. This prevents the stator 12 from rotating due to the reaction force to the output torque of the rotating electric machine 10.

[0063] (8) Adjacent electrical steel sheets 30 in the lamination direction are interlocked with each other. Therefore, when the electrical steel sheets 30 are laminated before welding, displacement of the electrical steel sheets 30 can be suppressed.

[0064] [Example of changes] Furthermore, each of the above embodiments can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0065] ○ In the above embodiment, the pair of end brackets 14 and 15 directly applied a restraining load to the first outer circumference 27 of the stator core 21, but a restraining load may also be applied indirectly.

[0066] For example, as shown in Figure 8, a first intervening member 61 may be positioned between the first end wall 41 and the first outer periphery 27 of the stator core 21 in the axial direction of the stator core 21. A second intervening member 62 may be positioned between the second end wall 51 and the first outer periphery 27 of the stator core 21 in the axial direction of the stator core 21. The pair of end brackets 14 and 15 apply a restraining load to the first outer periphery 27 of the stator core 21 via the first intervening member 61 and the second intervening member 62.

[0067] In this case, even if the number or position of the welded joints 25 of the stator core 21 changes, this can be accommodated simply by changing the number and arrangement of the first intervening member 61 and the second intervening member 62. Therefore, the same shape of end brackets 14 and 15 can be used for multiple types of stator cores 21 with different numbers and positions of welded joints 25.

[0068] Furthermore, it is preferable that the first intervening member 61 is not positioned between the first end wall 41 and the second outer periphery 28 of the stator core 21 in the axial direction of the stator core 21. It is also preferable that the second intervening member 62 is not positioned between the second end wall 51 and the second outer periphery 28 of the stator core 21 in the axial direction of the stator core 21. In this case, the pair of end brackets 14 and 15 can be prevented from applying a restraining load to the second outer periphery 28 of the stator core 21.

[0069] ○ The electromagnetic steel sheet 30 does not have to have a bent portion 34. Also, the electromagnetic steel sheet 30 arranged at one end in the lamination direction does not have to have a through hole 35. In other words, the stator core 21 does not have to have an engaging portion 26. In this case, the first end bracket 14 does not have to have a relief portion 44.

[0070] ○ Preferably, the depth from the first contact surface 43 to the bottom surface of the relief portion 44 is set to be greater than or equal to the difference between the axial thickness of the stator core 21 at the first outer peripheral portion 27 and the axial thickness of the stator core 21 at the second outer peripheral portion 28. If the depth from the first contact surface 43 to the bottom surface of the relief portion 44 is equal to the difference between the axial thickness of the stator core 21 at the first outer peripheral portion 27 and the axial thickness of the stator core 21 at the second outer peripheral portion 28, the second outer peripheral portion 28 of the stator core 21 will contact the bottom surface of the relief portion 44.

[0071] ○ Instead of the first end bracket 14, the second end bracket 15 may have a recessed portion that is recessed compared to the second contact surface 53. In this case, the stator core 21 is positioned such that the second outer circumference 28 faces the recess of the second end bracket 15. This prevents the pair of end brackets 14 and 15 from applying a restraining load to the second outer circumference 28 of the stator core 21.

[0072] ○ Not only the first end bracket 14, but also the second end bracket 15 may have a recessed portion that is more recessed than the second contact surface 53. In this case, it is preferable that the stator core 21 is positioned such that the second outer circumference 28 faces the recessed portion 44 of the first end bracket 14 and the recessed portion of the second end bracket 15 with respect to the pair of end brackets 14 and 15. This prevents the pair of end brackets 14 and 15 from applying a restraining load to the second outer circumference 28 of the stator core 21.

[0073] ○ In the above embodiment, a relief portion 44 was provided in the first end bracket 14 so that the pair of end brackets 14 and 15 would not impose a restraining load on the second outer circumference 28 of the stator core 21. However, a relief portion may also be provided in the stator core 21.

[0074] As shown in Figure 9, the first contact surface 43 of the first end bracket 14 is provided around the entire circumference of the first circumferential wall 42, excluding the opening 42b. However, it is not essential that the first contact surface 43 is provided around the entire circumference of the first circumferential wall 42, excluding the opening 42b. The first end bracket 14 may have the first contact surface 43 and the relief portion 44 alternating in the circumferential direction, as in the embodiment described above.

[0075] As shown in Figure 10, the second outer periphery 28 of the stator core 21 has a relief portion 70 that is recessed from the outer periphery surface of the stator core 21. The first outer periphery 27 of the stator core 21 overlaps with the first contact surface 43 in the axial direction of the stator core 21. On the other hand, the second outer periphery 28 of the stator core 21 does not overlap with the first contact surface 43 in the axial direction of the stator core 21 due to the relief portion 70. Therefore, the pair of end brackets 14 and 15 apply a restraining load to the first outer periphery 27 of the stator core 21, but do not apply a restraining load to the second outer periphery 28.

[0076] In this case, even if the number or position of the engaging portions 26 of the stator core 21 is changed, this can be accommodated simply by changing the number or position of the relief portions 70 of the stator core 21. Therefore, the same shape of end brackets 14 and 15 can be used for multiple types of stator cores 21 with different numbers or positions of engaging portions 26.

[0077] ○ The welded portion 33 of the electrical steel sheet 30 does not need to be recessed from the outer surface of the electrical steel sheet 30. ○ The resin coating is not limited to rust-preventive varnish. The resin coating may also be, for example, an adhesive for fixing the stator core 21 and the coil 22.

[0078] ○ The resin coating may be applied to surfaces other than the outer circumferential surface of the stator core 21, such as the inner circumferential surface of the yoke 23 or the side surface of the teeth 24. Also, if the resin coating is an adhesive for fixing the stator core 21 and the coil 22, the resin coating may be applied to the coil 22. In this case, the resin coating applied to the coil 22 may adhere to the stator core 21, causing the resin coating to penetrate between the electrical steel sheets 30.

[0079] ○ The fastening members are not limited to stud bolts B and nuts N. The fastening members may be, for example, bolts having a shaft portion with male threads on its outer circumference and a head portion at one end of the shaft portion. [Explanation of symbols]

[0080] 10... Rotating electric machine, 12... Stator, 14... First end bracket as an end bracket, 15... Second end bracket as an end bracket, 21... Stator core, 25... Welded part, 26... Engaging part, 27... First outer circumference, 28... Second outer circumference, 29... Varnish as a resin coating, 30... Electromagnetic steel sheet, 30a... First surface, 30b... Second surface, 34... Bent part, 34a... Convex part, 34b... Recess, 41... First end wall as an end wall, 42... First circumferential wall as a peripheral wall, 43... First contact surface as a contact surface, 44... Relief part, 51... Second end wall as an end wall, 52... Second circumferential wall as a peripheral wall, 53... Second contact surface as a contact surface, 61... First intervening member as an intervening member, 62... Second intervening member as an intervening member, 70... Relief part, 421... Tip surface, 521... Tip surface.

Claims

1. A stator having a cylindrical stator core made up of multiple stacked disc-shaped electromagnetic steel sheets, The resin coating provided on the stator, A pair of end brackets are arranged on both sides of the stator in the axial direction of the stator core, The fastening member provides a restraining load that restrains the stator core in the axial direction by fastening the pair of end brackets together by screwing a nut onto a bolt that is inserted through a bolt hole formed in one of the pair of end brackets and a bolt hole formed in the other of the pair of end brackets, The stator core has a welded portion formed by welding the outer surfaces of a plurality of electromagnetic steel sheets under pressure and compression, and a first outer peripheral portion which is the outer peripheral portion of the stator core where the welded portion is provided. The welded portion extends along the axial direction of the stator core on the outer circumferential surface of the stator core, The gap between the electrical steel sheets in the first outer periphery is smaller than the gap between the electrical steel sheets in other parts. The aforementioned end bracket is a bottomed cylindrical shape having an end wall and a cylindrical peripheral wall erected from the peripheral edge of the end wall. The end wall is located on one side of the stator in the axial direction of the stator core. The bolt hole extends through the peripheral wall from the end wall to the tip surface of the peripheral wall, The peripheral wall has, on the inner circumference of the leading edge of the peripheral wall, alternating contact surfaces that are recessed compared to the leading edge of the peripheral wall and relief portions that are even more recessed than the contact surfaces, in the circumferential direction of the peripheral wall. Each of the aforementioned electromagnetic steel sheets has a bent portion that is bent in the thickness direction, The bent portion has a convex portion that protrudes from the first surface of the electrical steel sheet and a concave portion that is recessed compared to the second surface, which is the surface opposite to the first surface of the electrical steel sheet. The stator core has an engagement portion in which a plurality of electromagnetic steel sheets are engaged in a concave-concave manner by the convex portion of the electromagnetic steel sheet engaging with the concave portion of the adjacent electromagnetic steel sheet. A rotating electric machine characterized in that, when the stator core is positioned between the pair of end brackets such that the welded portion faces the bolt inserted through the bolt hole, and the nut is screwed onto the bolt to fasten the pair of end brackets together, the contact surface contacts the first outer circumference, thereby directly applying a restraining load to the first outer circumference, and the relief portion does not directly apply a restraining load to the second outer circumference, which is the outer circumference of the stator core and the portion where the engaging portion is provided.

2. In the axial direction of the stator core, a plurality of intervening members are arranged between the first outer periphery of the stator core and the end bracket, and on the inner circumference of the periphery wall. The rotating electric machine according to claim 1, wherein the tip surface of the intervening member is positioned recessed from the tip surface of the peripheral wall to form the contact surface, and when the pair of end brackets are fastened together by the fastening member, it contacts the first outer periphery and applies a restraining load to the first outer periphery.

Images