Shrink-fit structure of rotary electric machine stator

Abstract

To suppress the positional deviation of a stator caused by shrink-fitting the stator to the inside of a case.SOLUTION: A shrink-fit structure 10 of a stator 2 of a rotary electric machine 1 has a structure in which an outer peripheral surface 2a of a roughly cylindrical stator 2 is fitted into an inside of a case 3 by shrink-fitting. The case 3 has a low-rigidity portion 31 and a high-rigidity portion 32 with higher radial rigidity than the low-rigidity portion 31 around the stator 2. At least one of the inner diameter of case 3 and the outer diameter of stator 2 is adjusted so that a shrink-fit allowance in the low-rigidity portion 31 is larger than a shrink-fit allowance in the high-rigidity portion 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shrink-fit structure for a stator of a rotating electrical machine in which the outer peripheral surface of a substantially cylindrical stator is fitted into the inside of a case by shrink fitting. [Background technology]

[0002] Patent Document 1 discloses a shrink-fit structure for a stator of a rotating electrical machine in which an outer circumferential surface of a substantially cylindrical stator is fitted into the inside of a housing by shrink fitting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-357472 A Summary of the Invention [Problem to be solved by the invention]

[0004] In power units of electric vehicles, hybrid vehicles, and the like, a structure is sometimes adopted in which the outer peripheral surface of a substantially cylindrical stator of a motor generator is fitted inside a case by shrink fitting. In such a shrink-fit structure of a stator, a repulsive force is generated according to the radial rigidity of the case during shrink fitting. Therefore, if the radial rigidity of the case is not uniform over the entire circumference, the repulsive force acting from the case toward the inside in the radial direction is not uniform over the entire circumference, and thus the stator may become misaligned after shrink fitting. When such a misalignment of the stator occurs, the air gap between the rotor and the stator is not uniform in the circumferential direction, which may be one of the factors causing misalignment of the rotating shaft.

[0005] In order to avoid such misalignment of the stator, it is conceivable to create a case with uniform radial rigidity over the entire circumference, and then assemble it to a separate case after shrink fitting. However, this method increases the number of parts, which increases costs and also increases the labor required for assembling the power unit.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a shrink-fitting structure for a stator of a rotating electrical machine that can suppress misalignment of the stator caused by shrink-fitting the stator into the inside of a case. [Means for solving the problem]

[0007] The shrink-fit structure of a stator of a rotating electric machine according to the present invention is a shrink-fit structure of a stator of a rotating electric machine in which the outer peripheral surface of a substantially cylindrical stator is fitted into the inside of a case by shrink-fitting, and is characterized in that the case has a low-rigidity portion around the stator and a high-rigidity portion having higher radial rigidity than the low-rigidity portion, and at least one of the inner diameter of the case and the outer diameter of the stator is adjusted so that the shrink-fit allowance in the low-rigidity portion is larger than the shrink-fit allowance in the high-rigidity portion. Effect of the Invention

[0008] The present invention can suppress misalignment of the stator that occurs when the stator is fitted inside the case by shrink fitting. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a shrink-fit structure of a stator of a rotating electric machine according to an embodiment of the present disclosure, viewed in the axial direction; [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 4 is a diagram showing the case before shrink fitting as viewed in the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a shrink-fit structure 10 for a stator of a rotating electric machine according to an embodiment of the present disclosure will be described with reference to Figs. 1 to 3. Fig. 1 is a diagram showing the shrink-fit structure 10 for a stator as viewed in the axial direction. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Figs. 1 and 2, in the shrink-fit structure 10 for a stator, an outer peripheral surface 2a of a stator 2 of a rotating electric machine 1 is fitted into a case 3 by shrink fitting.

[0011] The stator 2 is combined with the rotor 4 to form a rotating electric machine 1. Both the stator 2 and the rotor 4 have a substantially cylindrical shape. A cylindrical rotating shaft 5 is fitted into the rotor 4, and the rotating shaft 5 and the rotor 4 can rotate together. The rotating electric machine 1 may be used as an electric motor or a generator. The rotating electric machine 1 may be, for example, a rotating electric machine that is mounted on an electric vehicle or a hybrid vehicle and functions as an electric motor that generates a driving power source and also functions as a generator that generates electricity using regenerative torque or the like.

[0012] 1, the case 3 is provided around the stator 2 with a low-rigidity portion 31 and a high-rigidity portion 32 having a greater radial thickness than the low-rigidity portion 31. Since the radial thickness of the high-rigidity portion 32 is greater than the radial thickness of the low-rigidity portion 31, the radial rigidity of the high-rigidity portion 32 is greater than the radial rigidity of the low-rigidity portion 31. The low-rigidity portion 31 occupies approximately 270 degrees out of the total 360 degrees of the circumference of the case 3, and the high-rigidity portion 32 occupies approximately 90 degrees out of the total 360 degrees of the circumference of the case 3.

[0013] 3 is a diagram showing the case 3 in the axial direction before shrink fitting. As shown in FIG. 3, in the case 3 before shrink fitting, the inner diameter r2 of the high rigidity portion 32 is larger than the inner diameter r1 of the low rigidity portion 31 of the case 3. A step 33 is provided at the boundary between the inner peripheral surface 31a of the low rigidity portion 31 and the inner peripheral surface 32a of the high rigidity portion 32. In this manner, in the case 3 before shrink fitting, the inner diameter r2 of the high rigidity portion 32 is larger than the inner diameter r1 of the low rigidity portion 31. Therefore, when shrink fitting is performed to fit the stator 2 into the case 3, the shrink fitting allowance is smaller in the high rigidity portion 32 than in the low rigidity portion 31.

[0014] When shrink-fitting the stator 2 into the case 3, a repulsive force is generated from the case 3 toward the inside in the radial direction depending on the radial rigidity of the case 3. If the radial rigidity of the low-rigidity portion 31 is k1 and the shrink-fitting allowance of the low-rigidity portion 31 is x1, the following relationship in Equation 1 holds for the repulsive force f1 generated by the shrink-fitting of the low-rigidity portion 31.

[0015] f1=k1x1...Equation 1

[0016] Then, assuming that the radial rigidity of the high rigidity portion 32 is k2 and the shrink-fitting allowance of the high rigidity portion 32 is x2, the repulsive force f2 generated by the shrink-fitting of the high rigidity portion 32 satisfies the following formula 2.

[0017] f2=k2x2...Equation 2

[0018] The radial stiffness k1 of the low stiffness portion 31 and the radial stiffness k2 of the high stiffness portion 32 can be calculated from the shape of the case 3 by CAE (Computer-Aided Engineering) or the like. The inner diameter r1 of the low stiffness portion 31 and the inner diameter r2 of the high stiffness portion 32 are adjusted so that the repulsive force f1 of the low stiffness portion 31 and the repulsive force f2 of the high stiffness portion 32 are equal. As a result, the repulsive force generated from the case 3 toward the radially inward direction during shrink fitting is uniform over the entire circumference. Since the repulsive force generated from the case 3 toward the radially inward direction during shrink fitting is uniform over the entire circumference in this manner, the shrink fitting structure 10 of the stator can suppress the positional deviation of the stator 2 caused by shrink fitting.

[0019] <Supplementary explanation of the embodiment> The shrink-fit structure of the stator of the rotating electric machine of the present disclosure is not limited to the above-mentioned embodiment, and can be embodied in various embodiments within the scope of the gist of the present disclosure. For example, as a means for making the shrink-fit allowance of the high-rigidity portion smaller than that of the low-rigidity portion, a structure may be adopted in which the inner diameter of the high-rigidity portion of the case is the same as that of the low-rigidity portion, and the outer diameter of the stator facing the low-rigidity portion is smaller than that of the high-rigidity portion. Also, as a means for making the shrink-fit allowance of the high-rigidity portion smaller than that of the low-rigidity portion, a structure may be adopted in which the inner diameter of the high-rigidity portion of the case is larger than that of the low-rigidity portion, and the outer diameter of the stator facing the low-rigidity portion is smaller than that of the high-rigidity portion. [Explanation of symbols]

[0020] 1 rotating electric machine, 2 stator, 2a outer peripheral surface, 3 case, 4 rotor, 5 rotating shaft, 10 shrink-fit structure of stator, 31 low rigidity portion, 31a inner peripheral surface, 32 high rigidity portion, 32a inner peripheral surface, 33 step.

Claims

[Claim 1] A shrink-fit structure of a stator of a rotating electric machine in which an outer peripheral surface of a substantially cylindrical stator is fitted into an inside of a case by shrink fitting, the case includes a low-rigidity portion and a high-rigidity portion having a radial rigidity higher than that of the low-rigidity portion around the stator, A shrink-fit structure of a stator for a rotating electric machine, characterized in that at least one of an inner diameter of the case and an outer diameter of the stator is adjusted so that a shrink-fit allowance in the low rigidity portion is larger than a shrink-fit allowance in the high rigidity portion.

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