Rotor

Abstract

Disclosed is a rotor for a rotary electric machine, comprising: a shaft having a flange portion; a rotor core fitted with the shaft in such a manner that rotational torque can be transmitted between the shaft and the rotor core; a first end plate covering an end surface on one side of the rotor core in the axial direction; a second end plate covering an end surface on the other side of the rotor core in the axial direction; a nut member screwed to the shaft and sandwiching the rotor core with the flange portion in the axial direction; a first washer provided between the flange portion and the first end plate in the axial direction; and a second washer provided between the nut member and the second end plate in the axial direction, wherein the flange portion protrudes radially outward from an outer peripheral surface of the shaft that is fitted with the rotor core, and the first washer comes into contact with a seat surface of the flange portion in the axial direction and has an outer diameter larger than an outer diameter of the seat surface of the flange portion.

Description

[Technical field]

[0001] The present disclosure relates to a rotor. [Background technology]

[0002] A technology is known in which a rotor core is abutted axially against a flange portion (receiving portion) on one axial side of the shaft, and a nut member is tightened to the shaft from the other axial side, thereby clamping the rotor core between the flange portion and the nut member by the axial force generated by tightening the nut member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-100227 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described conventional technology, stress is likely to occur at the contact portion between the rotor core and the flange portion due to the axial force.

[0005] Therefore, an object of the present disclosure is to reduce stress that may occur in a rotor core due to axial force caused by tightening a nut member. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a rotor for a rotating electric machine, comprising: a shaft having a flange portion protruding radially outward at one axial end thereof; a rotor core that is fitted to the shaft in a manner that allows rotational torque to be transmitted between the rotor core and the shaft; a first end plate covering one end face of the rotor core in the axial direction; a second end plate covering the other end surface of the rotor core in the axial direction; a nut member that is screwed onto the shaft and that sandwiches the rotor core between the nut member and the flange portion in the axial direction; a first washer provided between the flange portion and the first end plate in the axial direction; a second washer provided between the nut member and the second end plate in the axial direction, The flange portion protrudes radially outward from an outer circumferential surface of the shaft in which the rotor core is fitted, A rotor is provided, in which the first washer axially abuts against the seating surface of the flange portion and has an outer diameter larger than the outer diameter of the seating surface of the flange portion. Effect of the Invention

[0007] According to the present disclosure, it is possible to reduce stress that may occur in a rotor core due to the axial force caused by tightening a nut member. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a schematic cross-sectional structure of a motor according to an embodiment; [Figure 1A] FIG. 2 is an enlarged view of a portion Q0 in FIG. [Diagram 2] FIG. 2 is an enlarged view of part Q1 in FIG. [Diagram 3] FIG. 2 is an enlarged view of part Q2 in FIG. [Figure 4] FIG. 2 is a cross-sectional view passing through the rotor shaft and the first washer, taken along a plane perpendicular to the rotation axis of the motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings.

[0010] FIG. 1 is a cross-sectional view that shows a schematic cross-sectional structure of a motor 1 (an example of a rotating electric machine) according to an embodiment. FIG. 1A is an enlarged view of a portion Q0 in FIG. 1. FIG. 2 is an enlarged view of a portion Q1 in FIG. 1. FIG. 3 is an enlarged view of a portion Q2 in FIG. 1. FIG. 4 is a cross-sectional view that passes through a rotor shaft 34 and a first washer 71, and is a cross-sectional view taken along a plane perpendicular to a rotating shaft 12 of the motor 1. FIG. 1 is a cross-sectional view taken along two planes that pass through the rotating shaft 12 of the motor 1 and are along lines L1 and L2 in FIG. 4.

[0011] 1 shows a rotating shaft 12 of a motor 1. In the following description, the axial direction refers to the direction in which the rotating shaft (center of rotation) 12 of the motor 1 extends, and the radial direction refers to the radial direction centered on the rotating shaft 12. Therefore, the radially outer side refers to the side away from the rotating shaft 12, and the radially inner side refers to the side toward the rotating shaft 12. In addition, the circumferential direction corresponds to the direction of rotation around the rotating shaft 12.

[0012] 1 also defines an X1 side and an X2 side along the direction of the rotation axis 12 (i.e., the axial direction). The X direction is parallel to the axial direction. In the following description, the terms X1 side and X2 side may be used to indicate a relative positional relationship.

[0013] The motor 1 may be a motor for driving a vehicle, for example, used in a hybrid vehicle or an electric vehicle, but the motor 1 may also be used for any other purpose.

[0014] The motor 1 is an inner rotor type, and the stator 21 is provided so as to surround the radial outside of the rotor 30. The radial outside of the stator 21 is fixed to the motor housing 10. The stator 21 includes a stator core 211 made of, for example, a circular ring-shaped laminated steel plate of a magnetic material, and a plurality of slots (not shown) around which the coils 22 are wound are formed on the radial inside of the stator core 211.

[0015] The rotor 30 is disposed radially inside the stator 21. The rotor 30 includes a rotor core 32 and a rotor shaft 34. The rotor core 32 is fixed to a radially outer surface of the rotor shaft 34 in a manner capable of transmitting rotational torque, and rotates integrally with the rotor shaft 34. The rotor core 32 may be fixed (fitted) to the rotor shaft 34 by shrink fitting, press fitting, or the like. In FIG. 1, the rotor core 32 faces in the radial direction a surface of the radially outer surface (outer peripheral surface) of the rotor shaft 34 that is in an axial range SC1 (see FIG. 1A). The rotor shaft 34 is rotatably supported by the motor housing 10 via bearings 14a and 14b. The rotor shaft 34 defines the rotating shaft 12 of the motor 1.

[0016] Rotor core 32 is made of, for example, laminated steel plates of a magnetic material having a circular shape. Permanent magnets 321 are embedded in magnet holes 324 of rotor core 32. Alternatively, permanent magnets such as permanent magnet 321 may be embedded in the outer circumferential surface of rotor core 32. The arrangement of permanent magnets 321 is arbitrary.

[0017] End plates 35A, 35B are attached to both axial sides of rotor core 32. End plates 35A, 35B cover the axial end faces of rotor core 32. End plates 35A, 35B may have a function of adjusting imbalance of rotor 30 (a function of eliminating imbalance by cutting or the like) in addition to a function of preventing permanent magnets 321 from coming off rotor core 32. In FIG. 1, end plates 35A, 35B radially face a surface of rotor shaft 34 that is in an axial range SC2 (see FIG. 1A) among the radially outer surfaces. Range SC2 is set on both sides (both axial sides) of range SC1 described above.

[0018] The end plates 35A, 35B are made of a non-magnetic material. The end plates 35A, 35B are preferably made of aluminum. In this case, cutting is easy and the end plates 35A, 35B can effectively adjust the imbalance of the rotor 30. However, in a modified example, the end plates 35A, 35B may be made of stainless steel or the like.

[0019] 1, the rotor shaft 34 has a hollow portion 34A. The hollow portion 34A extends over the entire axial length of the rotor shaft 34. The hollow portion 34A may be open in the axial direction on both axial sides. The hollow portion 34A extends over the entire axial length of the rotor shaft 34. The hollow portion 34A may function as an oil passage 801 through which cooling oil passes.

[0020] As shown in FIG. 1, a nut member 60 is provided on the rotor shaft 34.

[0021] The nut member 60 has, for example, a hexagonal outer shape when viewed in the axial direction, and a female thread portion is formed on the radially inner side. During assembly, after the rotor core 32 is assembled to the rotor shaft 34, the nut member 60 is screwed into a male thread portion formed on the radially outer surface of the rotor shaft 34 and tightened in the axial direction. As a result, the rotor core 32 is sandwiched in the axial direction between the flange portion 346 of the rotor shaft 34 and the nut member 60. In this case, an axial force is applied to the rotor core 32 by tightening the nut member 60.

[0022] 2, the seating surface 61 of the nut member 60 is a seating surface for a second washer 72 described later. That is, the second washer 72 described later is in surface contact with the seating surface 61 of the nut member 60. The seating surface 61 of the nut member 60 extends in a certain plane perpendicular to the axial direction. The seating surface 61 of the nut member 60 is in the form of a ring when viewed in the axial direction, and has an outer diameter r20.

[0023] In this manner, according to this embodiment, the rotor core 32 is abutted axially against the flange portion 346 (receiving portion) on the axial X1 side of the rotor shaft 34, and the nut member 60 is tightened to the rotor shaft 34 from the axial X2 side, whereby the rotor core 32 can be clamped between the flange portion 346 and the nut member 60 by the axial force generated by tightening the nut member 60.

[0024] In this embodiment, the magnetic pole configuration of rotor core 32 is arbitrary. For example, the number of magnetic poles may be eight or other than eight, and instead of or in addition to permanent magnet 321, pairs of permanent magnets forming each magnetic pole may be arranged such that the circumferential distance increases toward the radially outer side. Rotor core 32 may also be formed with a flux barrier, an oil passage, and the like.

[0025] In this embodiment, the rotor shaft 34 has a hollow portion 34A, but may be solid. The rotor shaft 34 may be formed by joining two or more parts. The motor 1 may be cooled by cooling water (e.g., Lifelong coolant) instead of or in addition to oil.

[0026] Next, the rotor 30 according to this embodiment will be described in more detail with further reference to Figures 1 to 4. Hereinafter, the term "axially inner" refers to a side relatively closer to the center of the rotor core 32 in the axial direction along the rotation axis 12, and the term "axially outer" refers to a side relatively farther from the center of the rotor core 32.

[0027] The rotor shaft 34 has a flange portion 346 that protrudes radially outward at one axial end side (axial X1 side). The flange portion 346 protrudes radially outward from the outer circumferential surface of the rotor shaft 34 with which the rotor core 32 is fitted. In Fig. 1, the rotor shaft 34 has the flange portion 346 over an axial range SC4 (see Fig. 1A). Of the radially outer surface of the rotor shaft 34, the axial range SC4 in which the flange portion 346 is formed is adjacent to a range SC3-1 (see Fig. 1A), described later, from the axially outer side.

[0028] The flange portion 346 has a brim-like shape around the rotating shaft 12, and has a seating surface 3461 (see FIG. 3) on the axially inner side. The flange portion 346 has a function of receiving an axial force generated by fastening a nut member 60 described later. The seating surface 3461 is a seating surface for a first washer 71 described later. That is, the first washer 71 described later abuts against the seating surface 3461 of the flange portion 346 in a face-to-face contact manner. The seating surface 3461 extends within a certain plane perpendicular to the axial direction. The seating surface 3461 has an annular shape when viewed in the axial direction, and has an outer diameter r10.

[0029] The rotor shaft 34 is provided with an angle R at a corner 345 adjacent to the seating surface 3461 of the flange portion 346 from the radially inner side. That is, the rotor shaft 34 is provided with an angle R at a corner 345 where the flange portion 346 protrudes radially outward from the outer circumferential surface where the rotor core 32 is fitted. The outer diameter of the outer circumferential surface of the rotor shaft 34 where the angle R starts may be the same as the outer diameter of the outer circumferential surface where the rotor core 32 is fitted (i.e., the outer diameter of the range SC1). The angle R may be formed over the entire circumference of the corner 345 around the rotating shaft 12, except for the range where the groove portion 349 described later is formed. It is desirable that the size (i.e., the radius) of the angle R is large from the viewpoint of reducing the stress generated in the flange portion 346. On the other hand, as the size of the angle R increases, the boundary position on the radially inner side of the seating surface 3461 moves radially outward, and the axial length of the range SC3-1 tends to become longer. If the boundary position of the radially inner side of the seat surface 3461 is located on the radially outer side, the axial force cannot be directly applied to the rotor core 32 on the radially inner side. In addition, if the axial length of the range SC3-1 is increased, the axial length of the rotor 30 is increased accordingly. Therefore, the axial thickness (i.e., radius) of the angle R may be approximately the thickness of the first washer 71 so as not to cause such inconvenience, and is, for example, significantly smaller than the sum of the thickness of the first washer 71 and the thickness of the end plate 35A, and is preferably equal to or smaller than the thickness of the first washer 71. This allows the first washer 71 to position the rotor core 32 in the axial direction while reducing the stress generated in the flange portion 346 and the axial length of the range SC3-1.

[0030] The rotor shaft 34 has a nut engagement portion 347 on the other axial end side (axial direction X2 side). In Fig. 1, the rotor shaft 34 has the nut engagement portion 347 over an axial range SC5. The axial range SC5 in which the nut engagement portion 347 is formed on the radially outer surface of the rotor shaft 34 is adjacent to a range SC3-2, which will be described later, from the axially outer side. Note that part of the nut engagement portion 347 may be formed in part of the range SC3-2 (a part adjacent to the range SC5).

[0031] The nut engagement portion 347 is in the form of a male screw portion that is threaded around the rotating shaft 12. A nut member 60 is screwed (screwed) into the nut engagement portion 347.

[0032] The outer diameter of the rotor shaft 34 is equal to or smaller than the outer diameter r1 (see FIG. 1) in the range SC1 in a section from the other axial end side (axial direction X2 side) to the axial position of the flange portion 346. Therefore, the rotor core 32 (and the end plates 35A, 35B, etc.) can be assembled to the rotor shaft 34 from the other axial end side.

[0033] The rotor shaft 34 has a concave groove 349 extending in the axial direction on the radially outer surface. The groove 349 is in the form of a key groove for a so-called key connection, and may be provided at two or more different circumferential positions (two in FIG. 4). The outer diameter r2 of the groove 349 (i.e., the outer diameter of the bottom surface of the groove 349 as shown in FIG. 4) is smaller than the outer diameter r1 by the depth. Convex portions 712 and 722 of a first washer 71 and a second washer 72 described later are fitted into the groove 349 (see FIG. 4 for the convex portion 712). The groove 349 may be formed in a surface portion having an outer diameter equal to or larger than the outer diameter r2 in a section from the end portion on the axial direction X2 side to the flange portion 346 of the radially outer surface of the rotor shaft 34. The groove 349 may be formed by rolling, cutting, or the like, or may be formed by a mold shape during casting.

[0034] In this embodiment, the rotor 30 further includes a first washer 71 and a second washer 72. Both the first washer 71 and the second washer 72 have an annular shape when viewed in the axial direction. Both the first washer 71 and the second washer 72 may be made of iron, a nonmagnetic material, or the like.

[0035] The first washer 71 is provided between the flange portion 346 and the rotor core 32 in the axial direction. The first washer 71 faces in the radial direction a surface (outer circumferential surface) of the rotor shaft 34 that is in the axial range SC3-1. As shown in FIG. 4, the first washer 71 engages with the radially outer surface of the rotor shaft 34. Specifically, the first washer 71 has a convex portion 712 on the radially inner side that protrudes radially inward, and the convex portion 712 fits into the groove portion 349 of the rotor shaft 34. The first washer 71 is positioned in the radial direction with respect to the rotor shaft 34 by fitting the convex portion 712 into the groove portion 349. Hereinafter, such a function provided by the convex portion 712 is also referred to as a "radial positioning function."

[0036] The first washer 71 has a function (hereinafter also referred to as a "stress reduction function") of reducing stress that may occur in the end plate 35A and the rotor core 32 due to the axial force applied from the flange portion 346 to the end plate 35A (and the rotor core 32 via the end plate 35A).

[0037] Specifically, as described above, rotor core 32 is sandwiched between flange portion 346 and nut member 60, and an axial force is applied by fastening nut member 60. That is, an axial compressive force of a magnitude corresponding to the magnitude of the axial force is applied to rotor core 32 between flange portion 346 and nut member 60. While such an axial force is useful for reliably holding rotor core 32 between flange portion 346 and nut member 60, it can also be a factor in generating stress in rotor core 32 (and end plates 35A, 35B).

[0038] In this regard, according to the present embodiment, the first washer 71 is interposed between the flange portion 346 and the rotor core 32, and therefore the stress generated in the end plate 35A and the rotor core 32 can be reduced compared to a case in which such a first washer 71 is not interposed.

[0039] The first washer 71 preferably has an outer diameter r5 that is significantly larger than the outer diameter r10 (see FIG. 3) of the seating surface 3461 of the flange portion 346 so that the above-mentioned stress reduction function is effectively achieved. In this case, the surface pressure due to the axial force applied to the rotor core 32 can be reduced compared to a case in which the first washer 71 is not interposed. That is, the range of the rotor core 32 that receives the surface pressure can be dispersed to the radially outer side related to the outer diameter r5. As a result, the stress generated in the end plate 35A and the rotor core 32 due to the axial force can be reduced.

[0040] Moreover, first washer 71 preferably has an inner diameter r6 (see FIG. 4) such that a portion other than protruding portion 712 does not come into radial contact with the radially outer surface of rotor shaft 34. That is, the inner diameter r6 of first washer 71 is preferably set such that first washer 71 does not ride up on corner R of corner portion 345 described above. This makes it possible to effectively achieve the radial positioning function of protruding portion 712 of first washer 71 described above.

[0041] The second washer 72 preferably has the same shape as the first washer 71. In this case, it becomes possible to share parts, and costs can be reduced. In this embodiment, as an example, the second washer 72 has the same shape as the first washer 71. However, in a modified example, the second washer 72 may have a shape different from that of the first washer 71.

[0042] The second washer 72 is provided between the nut member 60 and the rotor core 32 in the axial direction. The second washer 72 radially faces a surface relating to the axial range SC3-2 among the radially outer surface (outer circumferential surface) of the rotor shaft 34. The second washer 72 engages with the radially outer surface of the rotor shaft 34. Specifically, like the first washer 71, the second washer 72 has a convex portion 722 on the radially inner side that protrudes radially inward, and the convex portion 722 fits into the groove portion 349 of the rotor shaft 34.

[0043] The second washer 72 has a function of reducing stress (hereinafter also referred to as a "stress reducing function") that may occur in the end plate 35B and the rotor core 32 due to an axial force applied to the end plate 35B (and the rotor core 32 via the end plate 35B) from the nut member 60. That is, the second washer 72 has the same stress reducing function as the first washer 71 described above.

[0044] In this manner, according to the present embodiment, the second washer 72 is interposed between the nut member 60 and the rotor core 32, and therefore the stress generated in the end plate 35B and the rotor core 32 can be reduced compared to the case where such a second washer 72 is not interposed.

[0045] The second washer 72 preferably has an outer diameter r5 that is significantly larger than the outer diameter r10 (see FIG. 3) of the seating surface 61 of the nut member 60 so that the above-mentioned stress reduction function is effectively achieved. In this case, the surface pressure due to the axial force applied to the rotor core 32 can be reduced compared to a case in which the second washer 72 is not interposed. In other words, the range of the rotor core 32 that receives the surface pressure can be dispersed to the radially outer side related to the outer diameter r5. As a result, the stress generated in the end plate 35B and the rotor core 32 due to the axial force can be reduced.

[0046] In this embodiment, since end plate 35A (an example of a first end plate) is provided between rotor core 32 and first washer 71, the end plate 35A provides a function (such as the above-mentioned function of preventing permanent magnets 321 from coming off rotor core 32), but this can cause inconvenience due to the axial force acting on end plate 35A. The same applies to end plate 35B (an example of a second end plate).

[0047] In particular, when the end plates 35A, 35B are made of aluminum, creep, which is relatively noticeable in aluminum, can be a problem. That is, when the end plates 35A, 35B are made of aluminum, distortion of the end plates 35A, 35B increases over time due to the axial force, and problems such as a reduction in the axial force can occur.

[0048] In this regard, according to this embodiment, the stress reducing functions of the first washer 71 and the second washer 72 described above also function on the end plates 35A, 35B as described above. That is, by providing the first washer 71 and the second washer 72, it is possible to reduce the stress generated in the end plates 35A, 35B due to the axial force. As a result, even if the end plates 35A, 35B are made of aluminum, it is possible to reduce inconvenience caused by creep.

[0049] Furthermore, according to this embodiment, as described above, the rotor shaft 34 has the corner 345 on the radially inner side (root portion) of the flange portion 346 rounded, so that the stress concentration that tends to occur at the corner 345 can be reduced.

[0050] Here, when the corner portion 345 is given an R-angle, the stress concentration can be reduced as described above, but on the other hand, it becomes difficult to position the first washer 71 in the radial direction relative to the rotor shaft 34. This is because, when the first washer 71 rides up on the R-angle, the radial position is not determined. In this respect, according to the present embodiment, the radial positioning of the first washer 71 in the rotor shaft 34 can be easily achieved by the relationship between the convex portion 712 of the first washer 71 and the concave groove portion 349 of the rotor shaft 34. In this way, according to the present embodiment, the radial positioning of the first washer 71 in the rotor shaft 34 can be easily achieved while effectively reducing the stress that may be generated in the radially inner corner portion 345 of the flange portion 346.

[0051] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments.

[0052] For example, in the embodiment described above, the end plates 35A and 35B are provided, but one or both of the end plates 35A and 35B may be omitted.

[0053] In addition, in the above-described embodiment, the rotor shaft 34 is formed to be hollow, but it may be a solid member. [Explanation of symbols]

[0054] REFERENCE SIGNS LIST 1 motor (rotating electric machine), 34 rotor shaft (shaft), 345 corner portion, 346 flange portion, 3461 bearing surface, 349 groove portion, 32 rotor core, 60 nut member, 71 first washer, 72 second washer, 35A, 35B end plate (first end plate, second end plate)

Claims

1. A rotor for a rotating electric machine, a shaft having a flange portion protruding radially outward at one axial end thereof; a rotor core that is fitted to the shaft in a manner that allows rotational torque to be transmitted between the rotor core and the shaft; a first end plate covering one end face of the rotor core in an axial direction; a second end plate covering the other end surface of the rotor core in the axial direction; a nut member that is screwed onto the shaft and that sandwiches the rotor core between the nut member and the flange portion in the axial direction; a first washer provided between the flange portion and the first end plate in the axial direction; a second washer provided between the nut member and the second end plate in the axial direction, The flange portion protrudes radially outward from an outer circumferential surface of the shaft in which the rotor core is fitted, the first washer is in axial contact with the seat surface of the flange portion and has an outer diameter larger than an outer diameter of the seat surface of the flange portion, The second washer has an outer diameter larger than an outer diameter of a seat surface of the nut member.

2. The rotor according to claim 1 , wherein the first end plate and the second end plate are made of aluminum.

3. The shaft has a corner portion where the flange portion protrudes radially outward from an outer circumferential surface into which the rotor core is fitted, and a corner R is provided at the corner portion, The rotor according to claim 1 or 2, wherein a thickness of the first washer is equal to or greater than an axial thickness of the corner R.

4. The shaft has a concave groove extending in the axial direction on an outer circumferential surface thereof, The rotor according to claim 1 , wherein the first washer has a protrusion on a radially inner side thereof that fits into the groove.

5. A rotor according to claim 1 , wherein the first washer and the second washer are of the same configuration.

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