Rotor of rotating electrical machine

Abstract

To provide a rotor of a rotating electric machine capable of reducing the weight thereof while maintaining the moment of inertia about a rotation axis.SOLUTION: A rotor 10 of a rotating electric machine includes a rotor yoke 21 formed by laminating a plurality of electromagnetic steel sheets each having a substantially annular shape, and a rotor shaft 30 that is inserted into the rotor yoke 21 and rotates integrally with the rotor yoke 21. The rotor shaft 30 includes a metal portion 31 that penetrates the rotor yoke 21 and has one end serving as an output part or input part of the rotating electric machine, and a resin portion 40 that is provided on the outer peripheral side of the metal portion 31 and joined to a part of the metal portion 31. The metal portion 31 includes a large-diameter portion 32 provided on one end side, and a small-diameter portion 33 that is provided on the other side and has an outer diameter smaller than that of the large-diameter portion 32. The thickness T2 in a radial direction of a part of the resin part 40 to be joined to the small-diameter portion 33 of the metal portion 31 is larger than the outer diameter D2 of the small-diameter part 33.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotor for a rotating electric machine. [Background technology]

[0002] In recent years, efforts to realize a low-carbon or carbon-free society have been gaining momentum, and research and development into electrification technologies has been conducted in order to reduce CO2 emissions and improve energy efficiency in vehicles. Electrification technologies include rotating electrical machines such as electric motors and generators.

[0003] For example, a rotor used in a motor is described in Patent Document 1. In the rotor of Patent Document 1, a permanent magnet, a rotor yoke, and a boss are molded with resin and fixed in place. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4552267 Summary of the Invention [Problem to be solved by the invention]

[0005] By forming a part of the rotor from resin, it is possible to reduce the weight of the rotor, but this can reduce the moment of inertia around the rotation axis of the rotor, which can affect the motion characteristics of the rotor.

[0006] The present invention provides a rotor for a rotating electric machine that can be made lighter while maintaining the moment of inertia about the rotation axis. [Means for solving the problem]

[0007] The present invention relates to a rotor yoke formed by laminating a plurality of electromagnetic steel sheets each having a substantially annular shape; a rotor shaft inserted through the rotor yoke and rotating integrally with the rotor yoke, The rotor shaft is a metal part that passes through the rotor yoke and has one end that serves as an output part or an input part of the rotating electric machine; a resin portion provided on an outer circumferential side of the metal portion and joined to a part of the metal portion, the metal portion has a large diameter portion provided on the one end side and a small diameter portion provided on the other end side, the small diameter portion having an outer diameter smaller than that of the large diameter portion, The resin portion has a radial thickness at a portion joined to the small diameter portion of the metal portion that is greater than an outer diameter of the small diameter portion. Effect of the Invention

[0008] According to the present invention, it is possible to achieve weight reduction while maintaining the moment of inertia about the rotation axis. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a rotor 10 according to an embodiment of the present invention. [Diagram 2] 2 is a perspective view of the rotor yoke 21, the collar member 70, and the resolver rotor 60. FIG. [Diagram 3] 10 is a cross-sectional view of a modified example of the rotor 10. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotor for a rotating electrical machine according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0011] [Overall rotor structure] 1 and 2, the rotor 10 rotates about a rotation axis RC and has a generally annular shape centered on the rotation axis RC. The rotor 10 is disposed on the inner periphery of a stator (not shown) and, together with the stator, is one of the components that constitute a rotating electric machine such as an electric motor or a generator.

[0012] The rotor 10 includes a rotor yoke 21 having a substantially annular shape centered on a rotation axis RC, and a rotor shaft 30 that is inserted through the rotor yoke 21 and rotates integrally with the rotor yoke 21. Hereinafter, the direction in which the rotation axis RC extends is also referred to as the axial direction, and the direction perpendicular to the axial direction is also referred to as the radial direction.

[0013] The rotor yoke 21 is formed by stacking a plurality of electromagnetic steel plates in the axial direction, each having a substantially annular shape centered on the rotation axis RC. A plurality of permanent magnets 22 are embedded in the rotor yoke 21 along the circumferential direction. The permanent magnets 22 are arranged at equal intervals along the circumferential direction of the rotor yoke 21, and in the example of FIG. 2, a total of eight permanent magnets 22 are arranged at 45 degree intervals. Hereinafter, the rotor yoke 21 in which the permanent magnets 22 are embedded will also be referred to simply as the rotor yoke 21.

[0014] The inner circumferential surface 21a of the rotor yoke 21 is provided with a plurality of engagement portions 21a1 that engage with the rotor shaft 30. Each engagement portion 21a1 is, for example, a groove extending in the axial direction. As will be described in detail later, the resin portion 40 of the rotor shaft 30 engages with the engagement portions 21a1 and is joined to the rotor yoke 21, thereby enabling the rotor yoke 21 and the rotor shaft 30 to rotate integrally. Note that each engagement portion 21a1 is not limited to a groove, and may be, for example, a protrusion that protrudes toward the inner circumferential side.

[0015] The rotor shaft 30 extends in the axial direction around the rotation axis RC. For example, when the rotating electric machine functions as an electric motor, the rotor shaft 30 serves as an output shaft, and when the rotating electric machine functions as a generator, the rotor shaft 30 serves as an input shaft. In the following, the case where the rotating electric machine functions as an electric motor may be described as an example.

[0016] The rotor shaft 30 has a metal portion 31 made of metal and a resin portion 40 made of resin. In addition, in the axial direction, the right side in Fig. 1 is also referred to as a first side, and the left side is also referred to as a second side.

[0017] The metal part 31 is a solid shaft, and is provided so as to penetrate the rotor yoke 21. The metal part 31 has a large diameter part 32 provided on a first side, a small diameter part 33 provided on a second side, and a tapered part 34 connecting the large diameter part 32 and the small diameter part 33.

[0018] When viewed from the radial direction, the large diameter portion 32 is provided from an outer position on the first side of the rotor yoke 21 to an inner position of the rotor yoke 21, that is, a position overlapping the rotor yoke 21. The large diameter portion 32 serves as an input or output portion of a rotating electric machine, and is connected to a rotating body such as a gear. To be more specific, an axially extending key groove 37 is provided at an end portion 31a on the first side of the large diameter portion 32, and the rotating body is connected to the large diameter portion 32 by engaging with the key groove 37. When viewed from the radial direction, a part of the large diameter portion 32 is provided at a position overlapping the rotor yoke 21, and the radial distance between the rotor yoke 21 and the metal portion 31 is short. Therefore, for example, when the rotor yoke 21 rotates around the rotation axis RC and the rotation torque from the rotor yoke 21 is transmitted to the metal portion 31 via the resin portion 40, the transmission of the rotation torque to the metal portion 31 is good.

[0019] Small diameter portion 33 has an outer diameter D2 smaller than outer diameter D1 of large diameter portion 32, and is provided from an inner position of rotor yoke 21 to an outer position on the second side of rotor yoke 21 when viewed in the radial direction.

[0020] Further, a positioning portion 35 is provided at the second end 31b of the small diameter portion 33 as a structure for positioning the metal portion 31 in the rotation direction of the rotor 10 when the metal portion 31 is placed in a mold used for insert molding, which will be described later. The positioning portion 35 will be described later.

[0021] The tapered portion 34 connects, for example, in a straight line, the large diameter portion 32 and the small diameter portion 33. The tapered portion 34 is provided at a position overlapping the rotor yoke 21 when viewed in the radial direction.

[0022] The resin portion 40 is formed of, for example, a thermoplastic resin. The resin portion 40 is provided on the outer periphery of the metal portion 31, and is provided integrally with the metal portion 31 by insert molding. More specifically, the resin portion 40 is joined to the outer periphery of a part of the large diameter portion 32 of the metal portion 31, the tapered portion 34, and the small diameter portion 33. That is, a part of the rotor shaft 30 is configured to have a two-layer structure in which the metal portion 31 is arranged on the inside in the radial direction, and the resin portion 40 is arranged on the outside.

[0023] The resin part 40 has an intermediate part 40A that is provided at an inner position of the rotor yoke 21 when viewed from a radial direction, i.e., at a position overlapping the rotor yoke 21, and a first outer part 40B and a second outer part 40C that are provided at outer positions on the first and second sides of the rotor yoke 21 when viewed from a radial direction, i.e., at positions that do not overlap the rotor yoke 21.

[0024] The outer diameter of intermediate portion 40A of resin portion 40 is approximately the same as the inner diameter of rotor yoke 21. Intermediate portion 40A engages with a plurality of engaging portions 21a1 provided on inner peripheral surface 21a of rotor yoke 21 and is joined to rotor yoke 21. As a result, rotor yoke 21 and resin portion 40 rotate integrally around rotation axis RC.

[0025] A radial thickness T1 of the intermediate portion 40A of the resin portion 40 that is joined to the large diameter portion 32 of the metal portion 31 is smaller than an outer diameter D1 of the large diameter portion 32, but a radial thickness T2 of the intermediate portion 40A that is joined to the small diameter portion 33 of the metal portion 31 is larger than an outer diameter D2 of the small diameter portion 33. By providing a portion of the rotor shaft 30 in which the resin portion 40 has a large thickness in this manner, it is possible to reduce the weight of the rotor shaft 30. In the example shown in FIG. 1, the radial thicknesses T1 and T2 of the resin portion 40 are illustrated as the difference between the radius of the outer circumference and the radius of the inner circumference of the resin portion 40, but this is not limited thereto, and the thicknesses T1 and T2 may be the difference between the outer diameter and the inner diameter of the resin portion 40.

[0026] The second outer portion 40C of the resin portion 40 is provided with a resolver holding portion 43 that holds the resolver rotor 60.

[0027] The resolver rotor 60 held by the resolver holding portion 43, together with a resolver stator (not shown), constitutes a resolver capable of detecting rotation parameters (e.g., a rotation angle) of the rotor shaft 30. The resolver rotor 60 is joined to the resolver holding portion 43 so as to be rotatable integrally therewith.

[0028] The resolver rotor 60 is formed by laminating silicon steel plates having a substantially annular shape. On the outer circumferential surface of the resolver rotor 60, a plurality of protruding parts 62 are formed, which are evenly arranged in the circumferential direction and protrude radially outward in an arc shape. In this embodiment, four protruding parts 62 are formed and arranged at 90 degree intervals in the circumferential direction.

[0029] The first outer portion 40B of the resin portion 40 is provided with a positioning portion 44 that abuts against the rotor yoke 21 in the axial direction to regulate the axial position of the rotor yoke 21, and the second outer portion 40C is provided with a positioning portion 46 that abuts against the resolver rotor 60 outside the resolver holding portion 43 to regulate the axial position of the resolver rotor 60. The positioning portions 44, 46 are formed integrally with the resin portion 40, that is, are part of the resin portion 40. In addition, a collar member 70 is provided between the resolver rotor 60 and the rotor yoke 21. In this manner, the positioning portions 44, 46 and the collar member 70 determine the relative axial positions of the resolver rotor 60, the rotor yoke 21, and the rotor shaft 30.

[0030] The resin part 40 is provided on the first outer part 40B and the second outer part 40C, respectively, and has a first side bearing holding part 41 and a second side bearing holding part 42 that hold a bearing (not shown).

[0031] The first-side bearing retaining portion 41 and the second-side bearing retaining portion 42 have substantially the same outer diameter. Although not shown in the figure, the first-side bearing retaining portion 41 and the second-side bearing retaining portion 42 are rotatably supported via bearings on, for example, a case that houses a rotating electric machine.

[0032] As described above, the rotor 10 has the rotor shaft 30 made of metal and resin. Therefore, the weight of the rotor 10 can be reduced compared to a case where the entire rotor shaft is made of metal. In particular, the radial thickness T2 of the portion of the resin part 40 that is joined to the small diameter part 33 of the metal part 31 is greater than the outer diameter D2 of the small diameter part 33, which contributes to further reducing the weight of the rotor 10.

[0033] Furthermore, the moment of inertia about the rotation axis RC of the rotor 10 depends greatly on the outer diameter and the inner diameter of the rotor yoke 21. Therefore, even if the rotor shaft 30 arranged along the rotation axis RC is configured to include the resin part 40 as in this embodiment, it is possible to prevent the moment of inertia of the rotor 10 from changing significantly (i.e., becoming smaller) and to achieve weight reduction, compared to when the entire rotor shaft is made of metal.

[0034] Furthermore, if the entire rotor shaft were made of metal, it would be necessary to process the surface of the rotor shaft (for example, polishing the portion that is press-fitted into rotor yoke 21), which would increase the manufacturing cost of the rotor shaft. On the other hand, in this embodiment, the portion of rotor shaft 30 that is joined to rotor yoke 21 is resin part 40, so the cost of processing rotor shaft 30 can be reduced.

[0035] As described above, the resin part 40 is provided integrally with the metal part 31 by insert molding. Specifically, the resolver rotor 60, the collar member 70, the rotor yoke 21, and the metal part 31 are arranged in a mold (not shown), and a cavity formed in the mold is filled with molten resin to form the resin part 40, which is provided integrally with the resolver rotor 60, the collar member 70, the rotor yoke 21, and the metal part 31.

[0036] The metal part 31 of this embodiment is provided with the positioning part 35 described above, and when the metal part 31 is placed in the mold, the positioning part 35 engages with a positioning structure of the mold, thereby positioning the metal part 31 in the rotational direction of the rotor 10. The positioning part 35 is, for example, a key groove extending in the axial direction as shown in Fig. 1, and the key groove engages with a positioning structure of the mold (for example, a convex part), thereby positioning the metal part 31 in the rotational direction in the mold. The positioning part 35 may also be, for example, a minus groove provided in the end part 31b, and the minus groove engages with the positioning structure of the mold, thereby positioning the metal part 31 in the rotational direction in the mold.

[0037] (Modification) In the above-described embodiment, the metal part 31 has the large diameter part 32, the small diameter part 33, and the tapered part 34, but is not limited to this. For example, as shown in Fig. 3, the metal part 31 may have a configuration without the tapered part 34.

[0038] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. In addition, the components in the above embodiment may be arbitrarily combined within the scope of the invention.

[0039] This specification describes at least the following items. In parentheses, components corresponding to the above-described embodiment are shown as examples, but the present invention is not limited to these.

[0040] (1) a rotor yoke (rotor yoke 21) formed by laminating a plurality of electromagnetic steel sheets having a substantially annular shape; A rotor (rotor 10) for a rotating electric machine including a rotor shaft (rotor shaft 30) that is inserted into the rotor yoke and rotates integrally with the rotor yoke, The rotor shaft is a metal portion (metal portion 31) that passes through the rotor yoke and has one end side (first side) that serves as an output portion or an input portion of the rotating electric machine; a resin portion (resin portion 40) provided on the outer periphery of the metal portion and joined to a part of the metal portion, The metal portion has a large diameter portion (large diameter portion 32) provided on the one end side and a small diameter portion (small diameter portion 33) provided on the other end (second side) and having an outer diameter smaller than that of the large diameter portion, The resin portion has a radial thickness (thickness T2) at a portion joined to the small diameter portion of the metal portion that is greater than an outer diameter (outer diameter D2) of the small diameter portion. Rotor of a rotating electric machine.

[0041] According to (1), since the rotor shaft is made of metal and resin, the rotor can be made lighter than when the entire rotor shaft is made of metal. In particular, the radial thickness of the resin portion that joins to the small diameter portion of the metal portion is greater than the outer diameter of the small diameter portion, which contributes to reducing the weight of the rotor.

[0042] (2) A rotor for a rotating electric machine according to (1), a part of the large diameter portion of the metal portion is provided at a position overlapping the rotor yoke when viewed in a radial direction of the rotor; Rotor of a rotating electric machine.

[0043] According to (2), the transmission of rotational torque between the rotor yoke and the metal part is improved.

[0044] (3) A rotor for a rotating electric machine according to (1) or (2), The metal portion and the resin portion are integrally formed by insert molding. Rotor of a rotating electric machine.

[0045] According to (3), a rotor shaft in which the metal portion and the resin portion are integrated can be formed by insert molding. [Explanation of symbols]

[0046] 10 Rotor 21 Rotor yoke 30 rotor shaft 31 Metal Part 32 Large diameter section 33 Small diameter section 40 Resin part

Claims

1. a rotor yoke formed by laminating a plurality of electromagnetic steel sheets each having a substantially annular shape; a rotor shaft inserted through the rotor yoke and rotating integrally with the rotor yoke, The rotor shaft is a metal part that passes through the rotor yoke and has one end that serves as an output part or an input part of the rotating electric machine; a resin portion provided on an outer circumferential side of the metal portion and joined to a part of the metal portion, the metal portion has a large diameter portion provided on the one end side and a small diameter portion provided on the other end side, the small diameter portion having an outer diameter smaller than that of the large diameter portion, The resin portion has a radial thickness at a portion joined to the small diameter portion of the metal portion that is greater than an outer diameter of the small diameter portion. Rotor of a rotating electric machine.

2. 2. A rotor for a rotating electric machine according to claim 1, a part of the large diameter portion of the metal portion is provided at a position overlapping the rotor yoke when viewed from a radial direction of the rotor; Rotor of a rotating electric machine.

3. 3. A rotor for a rotating electric machine according to claim 1, The metal portion and the resin portion are integrally formed by insert molding. Rotor of a rotating electric machine.

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