Rotor member, rotor and electric motor

1. A rotor member which is fixed by press-fitting to a rotary shaft part of an electric motor, the rotor member comprising:

a cylindrical sleeve part having a first end at an axial-direction first side thereof, and a second end at an axial-direction second side thereof;

a plurality of magnet segments that are arranged to align in a circumferential direction at an outer side in the radial direction of the sleeve part; and

a cylindrical member that covers the plurality of the magnet segments from an outer side in the radial direction, and sandwiches the plurality of the magnet segments with the sleeve part,

wherein an inner circumferential face of the sleeve part has an inner circumferential tapered face in which the inside diameter of the sleeve part continuously increases at a fixed ratio in a direction from the first end towards the second end, and

wherein an outer circumferential face of the sleeve part has an outer circumferential tapered face in which the outside diameter of the sleeve part continuously decreases at a fixed ratio in a direction from the first end towards the second end, in an axial-direction segment of the sleeve part in which at least the inner circumferential tapered face is present,

wherein, in the rotor member in a state prior to the rotary shaft part being press fit into the sleeve part, an outer circumferential face of a plurality of the magnet segments has an outer circumferential tapered face in which an outside diameter of the rotating shaft part continuously decreases at a fixed ratio in a direction from the first end towards the second end, and a gap is formed between the outer circumferential face of the plurality of the magnet segments and the inner circumferential face of the cylindrical member, and

wherein, in the rotor member in a state after the rotary shaft part is press fit into the sleeve part, a gap is not formed between the outer circumferential face of the plurality of the magnet segments and the inner circumferential face of the cylindrical member, and the outer circumferential face of the plurality of the magnet segments and the inner circumferential face of the cylindrical member make surface contact.

2. A rotor of an electric motor comprising:

the rotor member according to claim 1 ; and

a rotary shaft part that is press-fit to the sleeve part of the rotor member,

wherein a portion of the outer circumferential face of the rotary shaft part, which is a portion at which the inner circumferential tapered face of the sleeve part abuts when the rotary shaft part is press-fitted to the sleeve part, has an outer circumferential tapered face at which the outside diameter of the rotary shaft part continuously increases at a fixed ratio in a direction from the first end towards the second end, and

wherein, in the rotor member in a state prior to the rotary shaft part being press-fit to the sleeve part,

when defining a taper rate of the inner circumferential tapered face of the sleeve part of the rotor member as t1,

defining a taper rate of the outer circumferential tapered face of the sleeve part of the rotor member as t2, and

in the rotary shaft part in a state prior to the rotary shaft part being press-fit to the sleeve part,

defining a taper rate of the outer circumferential tapered face of the rotary shaft part of the rotor as t3,

the rotor has a relationship of t1+t2=t3.

3. An electric motor comprising the rotor according to claim 2 .