US-20260128630-A1 - ROTOR FOR RESOLVER AND RESOLVER

US20260128630A1US 20260128630 A1US20260128630 A1US 20260128630A1US-20260128630-A1

Abstract

A rotor for a resolver is fixed to a shaft of a motor by press-fitting the shaft into a hole having a substantially circular shape. Two protruding parts are provided at an outer peripheral surface of the rotor and protrude radially outward in a circumferential direction at equal circumferential intervals, a protruding part located at a substantially central part in the circumferential direction of the protruding part and protruding toward the center of the hole is provided at an inner peripheral surface of the rotor, and a recessed part is located at a substantially central part in the circumferential direction of the protruding part opposite to the protruding part at 180° and recessed radially outward.

Inventors

Yoshiya Oono
Takaaki Ochiai

Assignees

MINEBEA MITSUMI INC.

Dates

Publication Date: 20260507
Application Date: 20230925
Priority Date: 20221003

Claims (8)

1 . A rotor for a resolver fixed to a shaft of a motor by press-fitting the shaft into a hole having a substantially circular shape, comprising: a plurality of protruding parts provided at an outer peripheral surface of the rotor and protruding radially outward in a circumferential direction at equal circumferential intervals, wherein a protruding part located at a substantially central part in the circumferential direction of the protruding part and protruding toward a center of the hole is provided at an inner peripheral surface of the rotor, and a recessed part is located at a substantially central part in the circumferential direction of another protruding part and recessed radially outward.
2 . The rotor for a resolver according to claim 1 , wherein a relief groove is formed at both sides of a root of the protruding part, extends in the circumferential direction of the inner peripheral surface, and extends radially outward from the inner peripheral surface.
3 . The rotor for a resolver according to claim 1 , wherein the relief groove comprises a pair of inclined surfaces extending in the circumferential direction of the inner peripheral surface of the rotor and radially outward from the inner peripheral surface, and a cylindrical surface connected to end parts of the inclined surfaces and forming a bottom part of the relief groove.
4 . The rotor for a resolver according to claim 2 , wherein second recessed parts are provided at both sides of the recessed part and have the same shape and size as a shape and a size of the relief groove.
5 . The rotor for a resolver according to claim 1 , wherein the number of the protruding parts at the outer peripheral surface of the rotor is two.
6 . The rotor for a resolver according to claim 4 , wherein the second recessed part is line-symmetrical to the relief groove with respect to a line connecting positions of 90° and 270° in the circumferential direction.
7 . The rotor for a resolver according to claim 1 , wherein the recessed part is a flat surface or an arc-shaped curved surface formed concentrically with the hole.
8 . A resolver comprising the rotor for the resolver according to claim 1 , wherein the rotor is located inside a stator, and a shaft of a motor having a key groove at an outer periphery of the shaft is press-fitted into the hole by fitting the protruding part into the key groove.

Description

TECHNICAL FIELD The present invention relates to a rotor for a resolver, and particularly, to an improvement in a structure for fixing a shaft of a motor to a rotor. BACKGROUND ART In the related art, as a rotor for this type of resolver, there is known a configuration having a protrusion protruding toward the center provided at an edge of an inner hole of the rotor and fitted into a recessed part serving as a key groove formed at an outer periphery of a shaft to integrally fix the rotor to the shaft (for example, see Patent Document 1). A rotor 1 described in Patent Document 1 has a shaft multiple angle of 2X (double angle), and one protrusion 3A is formed at an inner diameter wall 1Aa forming the inner diameter of an inner hole 1A of the rotor 1 to protrude to a shaft center P side, an outer periphery of the rotor 1 being a protruding part at two locations at the shaft multiple angle. An axially recessed part 11 serving as a key groove is formed at an outer periphery of a rotating shaft 10, and relief recessed parts 3Aa and 3Ab are formed at both sides of the protrusion 3A so that respective corner parts 11a and 11b formed at both sides of the axially recessed part 11 can enter and escape when the rotating shaft 10 is press-fitted into the inner hole 1A of the rotor 1 so that the protrusion 3A and the axially recessed part 11 are fitted. CITATION LIST Patent Document Patent Document 1: JP 2002-174535 A SUMMARY OF INVENTION Technical Problem In Patent Document 1, when the rotating shaft 10 is press-fitted into the inner hole 1A of the rotor 1 and the rotor 1 is fixed at the rotating shaft 10, the inner hole 1A has a non-circular shape due to press-fitting at the entire surface of an inner peripheral edge except for the periphery of the protrusion 3A, and stress at the time of press-fitting is not uniform in the circumferential direction. Therefore, the deformation of the two protruding parts at the outer peripheral surface of the rotor 1 is non-uniform, and an air gap between the protruding parts and a stator 100 is non-uniform. This causes waveform distortion of a rotation angle signal generated by the protruding part, and may affect the accuracy of an angle to be detected. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotor for a resolver capable of suppressing non-uniform deformation of a protruding part when a rotating shaft is press-fitted into the rotor. Solution to Problem The present invention is a rotor for a resolver fixed to a shaft of a motor by press-fitting the shaft into a hole having a substantially circular shape and, includes a plurality of protruding parts provided at an outer peripheral surface of the rotor and protruding radially outward in a circumferential direction at equal circumferential intervals, wherein a protruding part located at a substantially central part in the circumferential direction of the protruding part and protruding toward a center of the hole is provided at an inner peripheral surface of the rotor, and a recessed part is located at a substantially central part in the circumferential direction of another protruding part and recessed radially outward. Advantageous Effects of Invention The present invention can suppress non-uniform deformation of a protruding part when a shaft is press-fitted into a rotor. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view illustrating a rotor in an embodiment of the present invention. FIG. 2 is a plan view illustrating a resolver in the embodiment of the present invention. FIG. 3 is an enlarged view of a portion indicated by an arrow III in FIG. 1. FIG. 4 is an enlarged view of a portion indicated by arrow IV in FIG. 1. FIG. 5 is an enlarged view of a portion indicated by an arrow V in FIG. 2. FIG. 6 is an enlarged view of a portion indicated by an arrow VI in FIG. 2. FIG. 7 is a graph showing an outer diameter deformation amount of a rotor when a shaft is press-fitted into the rotor. DESCRIPTION OF EMBODIMENTS 1. Configuration of Rotor FIG. 1 is a view illustrating a rotor 10 for a variable reluctance (VR) type resolver. The rotor 10 is integrally formed by stacking a predetermined number of cores in an axial direction by caulking, welding, or the like, the core being formed by pressing a magnetic steel sheet (silicon steel sheet or electromagnetic steel sheet) into a predetermined shape (for example, a substantially elliptical shape). In the following description, assuming that the rotor 10 illustrated in FIG. 1 has a vertical center line, a position above the center line is 0°, a position below the center line 180°, and each position is indicated by an angle in a clockwise direction. A shaft multiple angle of the rotor 10 is a double angle (2X), and protruding parts 11 are formed at two locations of 0° and 180° at an outer peripheral surface of the rotor 10, for example, so as to have a substantially elliptical shape. A hole 12 having a substantial