Shrink-fit structure for rotating electrical 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 the outer peripheral 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] Japanese Patent Application Laid-Open No. 2004-357472 Summary of the Invention [Problem to be solved by the invention]

[0004] Power units for electric vehicles, hybrid vehicles, and the like often employ a structure in which the outer peripheral surface of a substantially cylindrical stator of a motor generator is fitted inside the case by shrink fitting. In such a shrink-fitted stator structure, a repulsive force is generated during shrink fitting depending on the radial rigidity of the case. Therefore, if the radial rigidity of the case is not uniform around the entire circumference, the repulsive force acting from the case toward the inside in the radial direction will not be uniform around the entire circumference, which can result in misalignment of the stator after shrink fitting. When this misalignment occurs, the air gap between the rotor and stator will not be uniform around the circumference, which can be a factor in causing misalignment of the rotating shaft.

[0005] One way to avoid this misalignment of the stator is to create a case with uniform radial rigidity around its entire circumference, and then assemble it into a separate case after shrink fitting. However, this method increases the number of parts, which increases costs and the labor required to assemble the power unit.

[0006] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a shrink-fit 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 an outer peripheral surface of a substantially cylindrical stator is fitted into an inside of a case by shrink-fitting, the case including, around the stator, a low-rigidity portion and a high-rigidity portion having radial rigidity higher than that of the low-rigidity portion; When performing shrink fitting to fit the stator into the case, the repulsive force generated from the case toward the inside in the radial direction in accordance with the rigidity of the case in the radial direction is adjusted so that the repulsive force of the low rigidity portion and the repulsive force of the high rigidity portion are equal. It is characterized by: [Effects of the Invention]

[0008] The present invention can suppress misalignment of the stator that occurs when the stator is fitted to the inside of the case by shrink fitting. [Brief explanation 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; [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 2 is a view showing the case in the axial direction before shrink fitting is performed. DETAILED DESCRIPTION OF THE INVENTION

[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 Figures 1 to 3. Figure 1 is a diagram showing the shrink-fit structure 10 for a stator as viewed in the axial direction. Figure 2 is a cross-sectional view taken along line AA in Figure 1. As shown in Figures 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 the 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, etc.

[0012] 1, the case 3 is provided around the stator 2 with a low-rigidity portion 31 and a high-rigidity portion 32 that is thicker in the radial direction than the low-rigidity portion 31. Because 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 higher 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 around the case 3, and the high-rigidity portion 32 occupies approximately 90 degrees out of the total 360 degrees around the case 3.

[0013] 3 is a diagram showing the case 3 as viewed 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 circumferential surface 31a of the low-rigidity portion 31 and the inner circumferential surface 32a of the high-rigidity portion 32. Because the inner diameter r2 of the high-rigidity portion 32 is larger than the inner diameter r1 of the low-rigidity portion 31 in the case 3 before shrink fitting, the shrink-fitting allowance when fitting the stator 2 into the case 3 by shrink fitting 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 relationship of the following formula 1 holds for the repulsive force f1 generated by shrink-fitting the low-rigidity portion 31.

[0015] f1=k1x1...Equation 1

[0016] When 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 relationship of the following formula 2.

[0017] f2=k2x2...Equation 2

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

[0019] <Supplementary information on the embodiment> The shrink-fit structure of the stator of the rotating electric machine of the present disclosure is not limited to the above-described embodiment and can be embodied in various forms within the scope 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 diameters of the high-rigidity portion and the low-rigidity portion of the case are the same, and the outer diameter of the portion of the stator facing the low-rigidity portion is smaller than that of the high-rigidity portion. Furthermore, 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 portion 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 part, 31a inner peripheral surface, 32 high rigidity part, 32a inner peripheral surface, 33 step

Claims

[Claim 1] A shrink-fit structure for 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 higher radial rigidity than the low-rigidity portion around the stator, A shrink-fit structure for a stator of a rotating electric machine, characterized in that the inner diameter of the low-rigidity portion and the inner diameter of the high-rigidity portion are adjusted so that the repulsive force generated radially inward from the case depending on the radial rigidity of the case when shrink-fitting the stator into the case is equal to the repulsive force of the low-rigidity portion.

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