rotor of an electric motor
By designing keyways and keys of specific shapes on the rotor core and shaft, and utilizing smooth curve connections and radial clearances, the problem of stress concentration during rotor rotation was solved, achieving uniform stress distribution and improved rotor stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-03-08
- Publication Date
- 2026-07-31
AI Technical Summary
In the prior art, the key portion of the rotor core is formed in a roughly rectangular shape, which may cause stress concentration during rotor rotation.
Keyways and keys of specific shapes are formed on the inner circumferential surface of the rotor core and the outer circumferential surface of the shaft. They are connected continuously by smooth curves, and radial clearance and interference are set to ensure stable engagement between the key and the keyway and suppress stress concentration.
It effectively suppresses stress concentration in the rotor core during rotation, distributes stress evenly, prevents rotor eccentricity, and improves rotor stability and durability.
Smart Images
Figure CN116742861B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the fixing structure of the rotor core and shaft constituting the rotor of an electric motor. Background Technology
[0002] The following method is proposed: As a structure for fixing the rotor core, which constitutes the rotor of an electric motor, to a shaft, a V-shaped keyway is formed on the outer circumferential surface of the shaft and a key is formed on the inner circumferential surface of the rotor core. The key of the rotor core is pressed into the keyway of the shaft for fixation. The structure described in Patent Document 1 is this structure.
[0003] Existing technical documents
[0004] [Patent Documents]
[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-123240 Summary of the Invention
[0006] The problem that the invention aims to solve
[0007] In the construction of Patent Document 1, the key portion of the rotor core is formed as a roughly rectangular shape, and the curve shape at the root of the key portion changes drastically. Therefore, stress concentration may occur around the root of the key portion during rotor rotation.
[0008] The present invention was made against the background described above, and its object is to provide a rotor for an electric motor that can suppress stress concentration in the rotor core during rotor rotation.
[0009] Methods for solving problems
[0010] The first embodiment is a rotor for an electric motor, (a) comprising a shaft and a cylindrical rotor core fixed to the outer circumferential surface of the shaft, characterized in that: (b) at least one keyway recessed toward the inner circumferential side is formed on the outer circumferential surface of the shaft; (c) at least one key portion protruding toward the inner circumferential side and fitting into the keyway in the assembled state is formed on the inner circumferential surface of the rotor core; (d) the inner circumferential surface of the rotor core is formed at least by a core bottom forming the top of the key portion, a core inclined portion inclined toward the outer circumferential side from the end of the core bottom, a core inner circumferential surface formed in an arc shape, and a core bending portion connecting the core inclined portion and the core inner circumferential surface; and (e) the portion of the key portion facing the keyway. (f) The outer circumferential surface of the shaft is formed by the continuous connection of the core bottom, the core inclined portion and the core bent portion in the circumferential direction of the rotor core. (g) The outer circumferential surface of the shaft is formed by at least the shaft bottom forming the groove bottom of the keyway, the shaft inclined portion inclined from the end of the shaft bottom toward the outer circumferential side, the shaft outer circumferential surface formed in an arc shape and the shaft bent portion connecting the shaft inclined portion and the shaft outer circumferential surface. (h) The portion of the keyway opposite to the key portion is formed by the continuous connection of the shaft bottom, the shaft inclined portion and the shaft bent portion in the circumferential direction of the shaft. (i) The core inclined portion and the shaft inclined portion are in contact with each other. (ii) A radial gap is formed between the core bent portion and the shaft bent portion.
[0011] The main point of the second approach is that, in the first approach, the inner circumferential surface of the rotor core is formed by a series of curves with different radii of curvature connecting the portion of the core inclined part that contacts the inclined part of the shaft to the inner circumferential surface of the core.
[0012] The main point of the third approach is that, in the first or second approach, the size of the gap is set to be less than 0.5 mm.
[0013] The main point of the fourth scheme is that, in any of the first to third schemes, the cross angle formed by the intersection of a pair of tangents at the point of contact with the axial tilt (38b) of the pair of core tilt portions (36b) constituting the key portion (34) is set to be in the range of 30 degrees or more and less than 180 degrees.
[0014] The fifth approach is characterized in that, in any of the first to fourth approaches, two fitting parts are provided where the keyway and the key portion are mutually fitted, and the two fitting parts are located opposite each other across the rotation axis of the rotor.
[0015] The sixth embodiment is characterized in that, in any one of the first to fifth embodiments, the inner circumferential surface of the rotor core is pressed into the outer circumferential surface of the shaft.
[0016] Invention Effects
[0017] According to the first embodiment, the portion of the key facing the keyway is formed such that the core bottom, the core inclined portion, and the core bent portion are continuously connected, and a radial gap is formed between the core bent portion and the shaft bent portion. Therefore, the inner circumferential surface of the rotor core, from the point where the core inclined portion contacts the shaft inclined portion to the inner circumferential surface of the core, can be formed using a smooth curve. Thus, even when high stress occurs in the core bent portion, the stress generated in that location can be evenly distributed. As a result, stress concentration in the rotor core can be suppressed.
[0018] According to the second scheme, the inner circumferential surface of the rotor core, from the contact point between the inclined portion of the core and the inclined portion of the shaft to the inner circumferential surface of the core, is continuously connected by multiple curves with different radii of curvature, thus forming a smooth curved shape. Therefore, the stress distribution acting on the core bending portion during rotor rotation is uniform, and stress concentration in the rotor core can be suppressed.
[0019] According to the third scheme, the gap size is set to less than 0.5mm, so that the inner circumferential surface of the core bending part can be formed into a smooth curved shape.
[0020] According to the fourth scheme, in a pair of core inclined portions constituting the key portion, the cross angle formed by the intersection of a pair of tangents at the part in contact with the shaft inclined portion is set to a range of 30 degrees or more and less than 180 degrees, so that the core inclined portion and the core curved portion can be connected by a smooth curve.
[0021] According to the fifth scheme, two fitting parts are arranged opposite each other at positions separated by the rotor's rotation axis, thus suppressing the offset of the rotor's center of gravity relative to the rotor's rotation axis. As a result, eccentricity during rotor rotation is suppressed.
[0022] According to the sixth embodiment, the inner circumferential surface of the rotor core is pressed into the outer circumferential surface of the shaft core, and the inner circumferential surface of the core is extended radially outward, generating tensile stress towards the inner circumferential surface of the core in the core bend. In contrast, the inner circumferential surface of the core bend is formed by a smooth curve, which enables the stress applied to the core bend to be evenly distributed. Attached Figure Description
[0023] Figure 1 This is a diagram showing the electric motor in which the present invention is applied, viewed along the direction of the rotation axis.
[0024] Figure 2 It's enlarged. Figure 1 Enlarged view of the key interlocking part.
[0025] Figure 3It is a diagram showing the stress distribution around the key portion of the rotor core during rotor rotation. Detailed Implementation
[0026] The following is a reference to the appendix. Figure 1 The embodiments of the present invention will be described in detail below. It should be noted that in the following embodiments, the figures are appropriately simplified or modified, and the dimensional ratios and shapes of the parts may not be accurately depicted.
[0027]
Example
[0028] Figure 1 This is a diagram showing the electric motor MG, to which the present invention is applied, viewed in the direction of the rotation axis CL. The electric motor MG is used, for example, as a driving force source for a vehicle. The electric motor MG is arranged in a housing (not shown) with the rotation axis CL as the center.
[0029] The electric motor MG has a stator 12 fixed to the housing by bolts or the like and a rotor 14 disposed on the inner circumference of the stator 12.
[0030] The stator 12 includes a cylindrical stator core 16 and stator coils 18 extending through the stator core in the direction of the rotation axis CL. The stator core 16 is constructed by stacking multiple insulated electromagnetic steel plates in the direction of the rotation axis CL. Slots 20 are formed in the stator core 16 as spaces extending radially from the inner circumference. Multiple slots 20 are formed at equal angular intervals in the circumferential direction of the stator core 16. Multiple stator coils 18 extending in the direction of the rotation axis CL are arranged in each slot 20. The cross-section of the stator coils 18 is rectangular, and the stator coils 18 are arranged radially within each slot 20.
[0031] The rotor 14 includes a rotor shaft 24 and a cylindrical rotor core 22 fixed to the outer circumferential surface of the rotor shaft 24. The rotor core 22 and the rotor shaft 24 are integrally fixed to each other and can rotate about the rotation axis CL. It should be noted that the rotor shaft 24 corresponds to the shaft of the present invention.
[0032] The rotor core 22 is constructed by stacking multiple insulated electromagnetic steel plates along the rotation axis CL. Multiple magnets 26 are embedded within the rotor core 22. The rotor shaft 24 is supported by bearings (not shown) located at both ends along the rotation axis CL, enabling it to rotate.
[0033] Two key fitting portions 28 are provided between the rotor core 22 and the rotor shaft 24. The key fitting portions 28 correspond to the fitting portions where the key portion 34 of the rotor core 22 (described later) and the keyway 32 of the rotor shaft 24 (described later) fit together. The two key fitting portions 28 are positioned opposite each other across the rotation axis CL. By providing the key fitting portions 28, relative rotation between the rotor core 22 and the rotor shaft 24 is prevented. Furthermore, by positioning the key fitting portions 28 opposite each other across the rotation axis CL, the shift of the rotor 14's center of gravity from the rotation axis CL can be suppressed, and eccentricity during the rotation of the rotor 14 is inhibited.
[0034] Figure 2 It's enlarged. Figure 1 An enlarged view of one of the two bond fitting portions 28. It should be noted that the other bond fitting portion 28 has the same structure, therefore its description is omitted. Furthermore, the bond fitting portion 28 corresponds to the fitting portion of the present invention.
[0035] The key fitting portion 28 is composed of a keyway 32 formed on the outer peripheral surface of the rotor shaft 24 and a key portion 34 formed on the inner peripheral surface of the rotor core 22.
[0036] The key portion 34 protrudes radially inward from the inner circumferential surface of the rotor core 22, and is continuously formed into an elongated shape parallel to the rotation axis CL. However, when viewed from the rotation axis CL direction, it is trapezoidal in shape. The keyway 32 is recessed radially inward from the outer circumferential surface of the rotor shaft 24, and is continuously formed into an elongated shape parallel to the rotation axis CL. Furthermore, when viewed from the rotation axis CL direction, the keyway 32 is V-shaped with a groove bottom. In the assembled state, the relative rotation of the rotor core 22 and the rotor shaft 24 is prevented by the interlocking of the keyway 32 and the key portion 34.
[0037] The inner circumferential surface of the rotor core 22 is composed of the core bottom 36a, the core inclined portion 36b, the core bent portion 36c, and the core inner circumferential surface portion 36d.
[0038] The bottom of the core 36a forms the top of the key portion 34, which is trapezoidal when viewed from the direction of the rotation axis CL.
[0039] The core inclined portion 36b is connected to the end of the core bottom 36a and slopes outward from the end of the core bottom 36a. The core inclined portion 36b forms an inclined portion of the key portion 34, which is trapezoidal when viewed from the rotation axis CL direction. Two core inclined portions 36b are formed relative to one key portion 34. The core inclined portion 36b is specifically formed by a curve with a radius of curvature Rc1. The connection between the core bottom 36a and the core inclined portion 36b has a curved shape in which the ends of each other are continuously and smoothly connected. It should be noted that the core inclined portion 36b can also be formed by a straight line, or it can be formed by multiple curves with different radii of curvatures, not just Rc1.
[0040] The core bend 36c is formed at the position connecting the core inclined portion 36b and the core inner peripheral surface portion 36d. The core bend 36c, forming the root of the key portion 34, is formed as an arc shape recessed radially outward. The core bend 36c is specifically formed by a curve with a radius of curvature Rc3. The connection between the core inclined portion 36b and the core bend 36c is formed, for example, by a curve with a radius of curvature Rc2, thereby ensuring a continuous and smooth connection between the core inclined portion 36b and the core bend 36c. It should be noted that the core bend 36c may also be formed by multiple curves with different radii of curvatures, not just Rc3.
[0041] The inner circumferential surface 36d occupies most of the inner circumferential surface of the rotor core 22 and is pressed into the outer circumferential surface 38d of the rotor shaft 24 (described later) during assembly. The inner circumferential surface 36d is formed in an arc shape, and in the portion forming the inner circumferential surface of the rotor core 22, the inner diameter dc has the largest dimension before assembly. Specifically, the inner circumferential surface 36d has… Figure 2 The inner diameter dc of the core is shown by a single-dotted line. The connection between the core bend 36c and the core inner peripheral surface 36d is formed, for example, by a curve with a radius of curvature Rc4, thereby continuously and smoothly connecting the core bend 36c and the core inner peripheral surface 36d.
[0042] The portion of the key 34 opposite to the keyway 32 is formed by a continuous connection of the core bottom 36a, the core inclined portion 36b, and the core bent portion 36c in the circumferential direction of the rotor core 22. It should be noted that... Figure 2 In the text, only one circumferential side of the key 34 is described, but the key 34 is relative to... Figure 2 The circumferential center line M shown is formed symmetrically on the left and right sides of the center line M that divides the bond 34 into two equal parts in the circumferential direction. Therefore, it is also formed on the other side of the circumferential direction of the bond 34.
[0043] The outer peripheral surface of the rotor shaft 24 is composed of the shaft bottom 38a, the shaft inclined portion 38b, the shaft bent portion 38c, and the shaft outer peripheral surface portion 38d.
[0044] The bottom 38a of the shaft forms a V-shaped groove bottom when the keyway 32 is viewed from the axis of rotation CL.
[0045] The inclined portion 38b forms an inclined section of the keyway 32 with a V-shaped cross-section, inclined from the end of the shaft bottom 38a toward the outer periphery. The inclined portion 38b is formed by a straight line. The connection between the shaft bottom 38a and the inclined portion 38b has a curved shape in which the ends of each other are continuously and smoothly connected.
[0046] Since the keyway 32 has a V-shaped cross-section, an inclined section 38b is also formed at the end of the keyway 32 on the opposite side in the circumferential direction. Here, the first intersection angle θ1 formed by the intersection of the straight lines L1 and L2 obtained by extending a pair of straight lines forming a pair of inclined sections 38b is suitable to be in the range of 30 degrees or more and less than 180 degrees. In this embodiment, the first intersection angle θ1 is set to 90 degrees. It should be noted that the first intersection angle θ1 corresponds to the intersection angle of the present invention.
[0047] The bent portion 38c is formed at the position connecting the inclined portion 38b and the outer peripheral portion 38d of the shaft. The bent portion 38c forms a portion near the exit of the keyway 32, and is formed in an arc shape bulging radially outward. The bent portion 38c is specifically formed by a curve with a radius of curvature Rs2. The connection between the inclined portion 38b and the bent portion 38c is formed, for example, by a curve with a radius of curvature Rs1, thereby ensuring a continuous and smooth connection between the inclined portion 38b and the bent portion 38c. It should be noted that the bent portion 38c may also be formed by multiple curves with different radii of curvatures, not just Rs2.
[0048] The outer circumferential surface 38d occupies most of the outer circumferential surface of the rotor shaft 24 and is pressed into the inner circumferential surface 36d of the rotor core 22 during assembly. The outer circumferential surface 38d is formed in an arc shape, and in the portion forming the outer circumferential surface of the rotor shaft 24, the outer diameter ds has the largest dimension before assembly. Specifically, the outer circumferential surface 38d has... Figure 2 The outer diameter ds of the shaft is shown by a single-dotted line. The connection between the curved portion 38c of the shaft and the outer peripheral portion 38d of the shaft is formed, for example, by a curve with a radius of curvature Rs3, thereby continuously and smoothly connecting the curved portion 38c of the shaft and the outer peripheral portion 38d of the shaft.
[0049] The portion of the keyway 32 opposite to the key portion 34 is formed by the continuous connection of the shaft bottom 38a, the shaft inclined portion 38b, and the shaft bent portion 38c in the circumferential direction of the rotor shaft 24.
[0050] The rotor core 22 and rotor shaft 24 are integrally fixed by pressing the inner circumferential surface 36d of the rotor core 22 into the outer circumferential surface 38d of the rotor shaft 24. Furthermore, the outer diameter ds of the outer circumferential surface 38d of the rotor shaft 24 before assembly is larger than the inner diameter dc of the inner circumferential surface 36d of the rotor core 22 before assembly. Therefore, an interference fit G is formed between the inner circumferential surface 36d and the outer circumferential surface 38d. Figure 1 In the part surrounded by the dotted line, an interference G is formed between the inner circumferential surface 36d of the core and the outer circumferential surface 38d of the shaft.
[0051] In the key fitting portion 28, a radial gap S1 is formed between the core bottom 36a and the shaft bottom 38a. On the other hand, in the key fitting portion 28, the core inclined portion 36b and the shaft inclined portion 38b are in contact with each other. Here, the core inclined portion 36b is specifically formed by a curve with a radius of curvature Rc1, while the shaft inclined portion 38b is formed by a straight line. Therefore, microscopically, the core inclined portion 36b makes point contact at the contact point X where it contacts the shaft inclined portion 38b, which is formed by a straight line. The contact point X is formed radially inward of the core inner circumferential surface 36d, which has a core inner diameter dc. It should be noted that the core inclined portion 36b and the shaft inclined portion 38b can be in a clearance fit, an interference fit, or a transition fit. In the case of an interference fit or a transition fit, the core inclined portion 36b and the shaft inclined portion 38b deform to achieve a line contact at least at the location including the contact point X. It should be noted that contact point X corresponds to the part that contacts the inclined shaft portion in the inclined core portion of the present invention.
[0052] As described above, in the rotor core 22, at least from the contact point X of the inclined portion 36b to the inner circumferential surface 36d, the inner circumferential surface of the rotor core 22 is formed into a curved shape obtained by continuously connecting multiple curves with different radii of curvature Rc (Rc1 to Rc4, etc.). Therefore, from the contact point X of the inclined portion 36b to the inner circumferential surface 36d, the radius of curvature Rc of the curve forming the inner circumferential shape of the rotor core 22 changes gradually.
[0053] Furthermore, a radial gap S2 is formed between the core bend 36c and the shaft bend 38c. The size of the gap S2 is set to a maximum value of 0.5 mm or less. The radius of curvature Rc3, which specifically forms the inner circumferential shape of the core bend 36c, and the radius of curvature Rs2, which specifically forms the outer circumferential shape of the shaft bend 38c, are set in such a way that the radius of curvature Rc3 of the core bend 36c is smaller than the radius of curvature Rs2 of the shaft bend 38c (Rs2>Rc3). By forming the gap S2, the degree of freedom of the inner circumferential shape of the inner circumferential surface of the core bend 36c is increased, allowing the core bend 36c to have a smooth shape. In addition, by limiting the maximum value of the gap S2 to 0.5 mm or less, the core bend 36c is formed by a smooth curve, for example, that does not protrude significantly to the outer circumferential side.
[0054] Furthermore, the core bending portion 36c is configured such that the second intersection angle θ2 formed by the intersection of tangents L3 and L4 is an obtuse angle. Tangent L3 passes through the connection point Y1 between the core bending portion 36c and the core inclined portion 36b, and tangent L4 passes through the connection point Y2 between the core bending portion 36c and the inner circumferential surface 36d. Because the second intersection angle θ2 is an obtuse angle, the inner circumferential surface of the core bending portion 36c is formed by a smooth curve. Even if high stress is applied to the core bending portion 36c, the stress distribution is uniform (i.e., approximately uniform), which can suppress stress concentration in the rotor core 22.
[0055] Figure 3 The analytical results of numerical simulation are shown, illustrating the stress distribution (stress distribution) acting on the periphery of the key portion 34 of the rotor core 22 during the rotation of the rotor 14. Figure 3 In the diagram, the part marked with a diagonal line above the paper corresponds to the rotor core 22, and the part below the paper corresponds to the rotor shaft 24.
[0056] exist Figure 3 In the rotor core 22, the finer the mesh spacing of the diagonal lines, the higher the stress. Therefore, the stress is higher towards the inner circumference of the core bend 36c of the rotor core 22, and the stress applied to the inner circumference of the core bend 36c is the greatest. In the rotor 14, an interference G is provided between the inner circumference surface 36d of the rotor core 22 and the outer circumference surface 38d of the rotor shaft 24. Therefore, a load is applied to the inner circumference surface 36d of the rotor core 22 in a direction that extends outward. At this time, tensile stress is generated in the core bend 36c in a direction that pulls towards the inner circumference surface 36d. In addition, if the contact point X of the core inclined portion 36b is subjected to a load in the rotational direction, a bending load is generated relative to the key portion 34. At this time, bending stress is generated at the root of the key portion 34 due to the bending load relative to the key portion 34. As a result, the tensile load on the inner peripheral surface 36d side of the core and the bending load at the root of the key 34 are superimposed, resulting in high stress at the root of the key 34, i.e., the core bending portion 36c.
[0057] In contrast, since the inner circumferential surface from the contact point X of the inclined core portion 36b to the inner circumferential surface portion 36d of the core is formed as a curved shape with multiple curves of different radii of curvature Rc (Rc1 to Rc4, etc.) smoothly connected, the stress distribution on the inner circumferential surface of the bent core portion 36c is uniform. As a result, stress concentration in the bent core portion 36c can be suppressed.
[0058] Furthermore, the first crossing angle θ1 formed by the intersection of a pair of straight lines L1 and L2 obtained by extending the straight lines forming a pair of inclined shaft portions 38b is set to a range of 30 degrees to 180 degrees. Relatedly, the first crossing angle θ1 formed by the intersection of a pair of tangents (i.e., straight lines L1 and L2) through the core inclined portion 36b and the contact point X of the inclined shaft portion 38b is also set to a range of 30 degrees to 180 degrees. By setting the first crossing angle θ1 to the above range, the inner circumferential surface of the rotor core 22 from the contact point X of the core inclined portion 36b to the inner circumferential surface 36d of the core can achieve a smooth curved shape. On the other hand, if the first crossing angle θ1 is less than 30 degrees, the inclination of the core inclined portion 36b becomes steeper, and therefore the change in the curved shape of the inner circumferential surface of the core bent portion 36c becomes drastic. As a result, stress concentration is more likely to occur in the core bent portion 36c.
[0059] As described above, according to this embodiment, the portion of the key portion 34 facing the keyway 32 is formed such that the core bottom 36a, the core inclined portion 36b, and the core bent portion 36c are continuously connected, and a radial gap S2 is formed between the core bent portion 36c and the shaft bent portion 38c. Therefore, the inner circumferential surface of the rotor core 22, from the contact point X where the core inclined portion 36b contacts the shaft inclined portion 38b to the inner circumferential surface portion 36d, can be formed using a smooth curve. Therefore, even when high stress is generated in the core bent portion 36c, the stress generated in that location can be evenly distributed. As a result, stress concentration in the rotor core 22 can be suppressed.
[0060] Furthermore, according to this embodiment, the inner circumferential surface of the rotor core 22, from the contact point X where the core inclined portion 36b contacts the shaft inclined portion 38b to the inner circumferential surface 36d, is continuously connected by multiple curves with different radii of curvature Rc, thus forming a smooth curved shape. Therefore, the stress distribution acting on the core bending portion 36c during the rotation of the rotor 14 is uniform, and stress concentration in the rotor core 22 can be suppressed. In addition, since the size of the gap S2 is set to 0.5 mm or less, the inner circumferential surface of the core bending portion 36c can be formed into a smooth curved shape. Furthermore, since the first intersection angle θ1 formed by the intersection of a pair of tangents (straight lines L1, L2) at the contact points X where the pair of core inclined portions 36b contacts the shaft inclined portion 38b constituting the key portion 34 intersects is set to a range of 30 degrees or more and less than 180 degrees, the core inclined portion 36b and the core bending portion 36c can be connected by a smooth curve.
[0061] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is also applicable to other embodiments.
[0062] For example, in the aforementioned embodiment, two key fitting portions 28 are provided on the rotor 14 at positions opposite each other across the rotation axis CL, but the number of key fitting portions 28 is not necessarily limited to two. For example, three, four or more key fitting portions 28 may also be provided.
[0063] Furthermore, in the aforementioned embodiment, the inner circumferential surface of the rotor core 22, from the contact point X of the inclined core portion 36b to the inner circumferential surface portion 36d, is formed by continuously connecting curves with curvature radii Rc1 to Rc4. However, the curvature radii Rc forming the inner circumferential surface of the rotor core 22 are not necessarily limited to these four radii Rc1 to Rc. For example, the inner circumferential surface of the rotor core 22 can also be formed by continuously connecting curves with five or more curvature radii Rc. In short, the inner circumferential surface of the rotor core 22 can be smoothly formed by continuously connecting curves with multiple curvature radii Rc.
[0064] It should be noted that the above is only one implementation method, and the present invention can be implemented with various changes and improvements based on the knowledge of those skilled in the art.
[0065] Explanation of reference numerals in the attached figures
[0066] 14: Rotor
[0067] 22: Rotor core
[0068] 24: Rotor shaft (shaft)
[0069] 28: Key mating part (mating part)
[0070] 32: Keyway
[0071] 34: Key part
[0072] 36a: Bottom of the core
[0073] 36b: Core tilting portion
[0074] 36c: Core bending section
[0075] 36d: Core inner periphery face
[0076] 38a: Bottom of shaft
[0077] 38b: Inclined section of shaft
[0078] 38c: Shaft bending section
[0079] 38d: Axial peripheral face
[0080] MG: Electric motor
[0081] CL: Axis of rotation
[0082] S2: Gap
[0083] Rc1~Rc4: Radius of curvature
[0084] θ1: First cross angle (cross angle).
Claims
1. A rotor (14) for an electric motor (MG), comprising a shaft (24) and a cylindrical rotor core (22) fixed to the outer circumferential surface of said shaft (24), characterized in that, At least one keyway (32) recessed toward the inner circumferential side is formed on the outer circumferential surface of the shaft (24). At least one key portion (34) is formed on the inner circumferential surface of the rotor core (22), protruding toward the inner circumferential side and fitting into the keyway (32) in the assembled state. The inner circumferential surface of the rotor core (22) is formed by at least a core bottom (36a) forming the top of the key portion (34), a core inclined portion (36b) inclined from the end of the core bottom (36a) toward the outer circumferential side, a core inner circumferential surface portion (36d) formed in an arc shape, and a core curved portion (36c) connecting the core inclined portion (36b) and the core inner circumferential surface portion (36d). The portion of the key (34) facing the keyway (32) is formed by the core bottom (36a), the core inclined portion (36b), and the core bent portion (36c) being continuously connected in the circumferential direction of the rotor core (22). The outer peripheral surface of the shaft (24) is formed by at least a shaft bottom (38a) forming the bottom of the keyway (32), a shaft inclined portion (38b) that slopes from the end of the shaft bottom (38a) toward the outer peripheral side, a shaft outer peripheral portion (38d) formed in an arc shape, and a shaft curved portion (38c) connecting the shaft inclined portion (38b) and the shaft outer peripheral portion (38d). The portion of the keyway (32) facing the key portion (34) is formed by the continuous connection of the shaft bottom (38a), the shaft inclined portion (38b), and the shaft bent portion (38c) in the circumferential direction of the shaft (24). The core inclined portion (36b) and the shaft inclined portion (38b) are in contact with each other. A radial gap (S2) is formed between the core bending portion (36c) and the shaft bending portion (38c).
2. The rotor (14) of the electric motor (MG) according to claim 1, characterized in that, Between the portion of the core inclined portion (36b) that contacts the shaft inclined portion (38b) and the inner circumferential surface of the core (36d), the inner circumferential surface of the rotor core (22) is formed by a series of curves with different radii of curvature (Rc1-Rc4).
3. The rotor (14) of the electric motor (MG) according to claim 1 or 2, characterized in that, The size of the gap (S2) is set to be less than 0.5 mm.
4. The rotor (14) of the electric motor (MG) according to any one of claims 1 to 3, characterized in that, In the pair of core tilted portions (36b) constituting the key portion (34), the cross angle (θ1) formed by the intersection of a pair of tangents at the portion in contact with the shaft tilted portion (38b) is set to a range of 30 degrees or more and less than 180 degrees.
5. The rotor (14) of the electric motor (MG) according to any one of claims 1 to 4, characterized in that, The keyway (32) is provided with two fitting parts (28) that fit together with the key (34). The two fitting parts (28) are positioned opposite each other across the rotation axis (CL) of the rotor (14).
6. The rotor (14) of the electric motor (MG) according to any one of claims 1 to 5, characterized in that, The inner circumferential surface (36d) of the rotor core (22) is pressed into the outer circumferential surface (38d) of the shaft (24).