JP5065877B2 - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric motor equipped with an eccentricity permissible structure, which suppresses an increase in cost and weight. <P>SOLUTION: The electric motor is provided with: a rotor 3 provided with a rotating shaft 2; a stator 4 disposed to oppose the rotor in a shaft direction; and a case 5 having the rotor and the stator incorporated therein and fixing a stator on the inner surface thereof. A free bearing 7 for permitting the eccentricity of the rotor in a direction perpendicular to the center line of the stator is provided between the inner surface of the case and the rotor. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an electric motor, and more particularly to an electric motor having a structure for allowing eccentricity of a rotating shaft.

2. Description of the Related Art Conventionally, as an electric motor corresponding to an electric motor that requires low speed and high torque, there is an axial gap type electric motor in which a stator and a rotor are arranged to face each other in the direction of a rotation axis. A conventional axial gap type electric motor includes a stator around which a coil is wound, a rotor that is arranged to face the coil in the direction of the rotation axis, and a plurality of pairs of permanent magnets are arranged in a circumferential magnetomotive force type. And a rotating magnetic field is generated by passing an electric current through the stator coil, and the rotor is rotated by a magnetic attraction force and a repulsive force between the stator and the rotor (Patent Documents 1 and 2). See
JP 2002-153028 A Japanese Patent Laid-Open No. 11-187635

  However, in these conventional axial gap type electric motors, the center line of the stator and the center line of the rotor are configured to be coaxial, and for example, the rotation center line of the rotated member connected to the rotor is also the center line of the rotor. Need to be the same. However, variation cannot be removed in consideration of assembly accuracy and the like. In order to allow deviation (eccentricity) of the center line, conventionally, an Oldham coupling has been installed between the rotor and the rotated member. For this reason, the subject of a cost increase and a weight increase arises with the setting of Oldham coupling.

  The present invention has been made in view of the above problems, and an object thereof is to suppress an increase in cost and weight in an electric motor having an eccentricity allowing structure.

  The present invention includes a rotor having a rotating shaft, a stator arranged so as to face the rotor in the axial direction, the rotor and the stator, and the stator on the inner surface thereof. In the electric motor including a case to be fixed, a free bearing is provided between the inner surface of the case and the rotor to allow eccentricity of the rotor in a direction perpendicular to the center line of the stator.

  In the present invention, since a free bearing is provided between the rotor and the case, the free bearing allows eccentricity between the rotor centerline and the stator centerline, and conventionally allows eccentricity. The existing Oldham coupling can be abolished, and an increase in cost and weight can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of an axial gap type electric motor 1 of the present invention.

  In the present embodiment, the axial gap type electric motor 1 includes a rotor 3 having a rotating shaft 2 and a pair of stators 4 facing the rotor 3 with a predetermined gap in the axial direction of the rotating shaft 2. 5 and is configured.

  A rotating shaft 2 extending in the axial direction is fixed to the rotor 3, and the rotor 3 includes a disk-shaped flange 11 having a plane orthogonal to the axial direction, and a plurality of flanges 11 fixed to the outer periphery of the flange 11. A permanent magnet 12. The permanent magnets 12 are arranged at equal intervals in the circumferential direction.

  The stator 4 is wound around the tooth portion 9, a yoke portion 8 fixed to the case 5, a plurality of teeth portions 9 protruding from the yoke portion 8 toward the rotor 3, and provided at predetermined intervals in the circumferential direction. The coil 10 is configured. The yoke part 8 plays a role of fixing the tooth part 9 to the case 5 and rotating the magnetic flux of the tooth part 9 in the circumferential direction to flow to another tooth part 9. The coil 10 wound around each tooth portion 9 faces each permanent magnet 12 of the rotor 3 in the axial direction of the rotating shaft 2. The coil 10 is wound around the tooth portion 9 via an insulator (not shown) and is insulated from the tooth portion 9.

  The case 5 includes the rotor 3 and the stator 4 therein, and includes a bottomed cylindrical main body 5a and a lid 5b that closes the opening of the main body 5a. A through hole 5c through which the rotary shaft 2 passes is formed in the lid 5b. Each yoke portion 8 of the stator 4 that faces the permanent magnet 12 of the rotor 3 in the axial direction is fixed to the bottom portion 5d and the lid portion 5b of the main body portion 5a of the case 5. The rotor 3 and the stator 4 are installed such that the axial gap 14 has a predetermined value.

  The through hole 5 c of the case 5 is formed larger by a predetermined amount than the outer diameter of the rotating shaft 2. The relative displacement (eccentricity) of the rotor 3 with respect to the case 5 in the direction orthogonal to the center line of the stator 4 (hereinafter referred to as the direction perpendicular to the axis) is the inner diameter of the through hole 5c and the rotational shaft 2. It is defined by the difference from the outer diameter.

  Next, a configuration that allows relative displacement of the rotor 3 in the direction perpendicular to the axis will be described.

  The outer diameter of the flange 11 fixed to the rotating shaft 2 is formed larger than the inner diameter of the through hole 5 c of the lid portion 5 b of the case 5. Specifically, the outer diameter of the flange 11 is set to be always larger than the through-hole 5c even if the rotation shaft 2 is eccentric by a maximum amount with respect to the direction perpendicular to the axis of the case 5.

  Free bearings 7 are respectively installed on the bottom 5d and the lid 5b of the main body 5a of the case 5, and a plurality of balls 7a of the free bearing 7 are in contact with the flat surfaces 11a and 11b of the flange 11 from both sides.

  Referring to FIGS. 2 to 4, the free bearing 7 is formed in an annular shape and is arranged coaxially with the center line of the stator 4. The free bearing 7 includes a surface 7a formed in parallel with the flat surfaces 11a and 11b forming the front and back of the flange 11, and is accommodated in a base 7b fixed to the case 5 and a plurality of hemispherical concave portions 7e formed in the surface 7a. And a support member 7d that is interposed between the recess 7e and the ball 7c and supports the ball 7c so that it can roll on the flange 11. The support member 7d is composed of a resin bearing or a plurality of small-diameter balls.

  As shown in FIG. 2, the balls 7c are arranged at regular intervals in the circumferential direction (α1 = α2), and the inner diameter D1 of the base 7b of the free bearing 7 is set as large as possible than the through hole 5c, and the outer diameter D2 The difference D2-D1 between the inner diameter D1 and the inner diameter D1 is set as small as possible, and the diameter of the ball 7c is set large.

  With such a configuration, the flange 11 of the rotor 3 is clamped from the axial direction by the pair of free bearings 7, and the ball 7 c of the free bearing 7 rolls when the rotor 3 is displaced in the direction perpendicular to the axis with respect to the stator 4. The relative displacement of the rotor 3 with respect to the stator 4 is made possible.

  In addition, although the structure which arrange | positions the free bearing 7 in the stator 4 side was demonstrated, it is also possible to arrange a free bearing in the rotor 3 side.

  Next, the operation will be described.

  The axial gap type electric motor of the present invention includes, for example, a coil of the stator 4 in a state where the case 5 is fixed to a support member (not shown) and the rotary shaft 2 to which the rotor 3 is fixed is connected to a rotated member (not shown). Operation is performed by energizing 10. When the coil 10 of the stator 4 is energized, a rotating magnetic field is generated, and accordingly, the rotor 3 rotates in a predetermined direction by a magnetic attractive force and a repulsive force between the stator 4 and the rotor 3. With this rotation, the rotating shaft 2 also rotates.

  In the present invention, since the free bearing 7 is provided between the case 5 and the rotor 3, the rotor 3 can allow displacement in a direction perpendicular to the center line of the stator 4 with an easy configuration. Thereby, an increase in cost and an increase in weight can be suppressed while having an eccentric function.

  The inner diameter D1 of the base 7b of the free bearing 7 is set as large as possible than the through hole 5c, and the difference D2-D1 between the outer diameter D2 and the inner diameter D1 is set as small as possible. Can be set large. Further, since the diameter of the ball 7c is set large, the surface pressure of the ball 7c can be reduced, and the allowable rotational speed of the rotor 3 can be improved against the axial pressing force acting on the ball 7c.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

It is sectional drawing explaining the structure of the axial direction air gap type | mold electric motor 1 of this invention. It is a block diagram of a free bearing. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axial direction gap type motor 2 Rotating shaft 3 Rotor 4 Stator 5 Case 5a Body part 5b Cover part 5c Through-hole 7 Free bearing 8 Yoke part 9 Teeth part 10 Coil 11 Flange

Claims (3)

A rotor with a rotation axis;
A stator arranged to face the rotor in the axial direction;
In the electric motor provided with a case for internally arranging the rotor and the stator and fixing the stator to the inner surface thereof,
An electric motor comprising a free bearing that allows eccentricity of the rotor in a direction orthogonal to a center line of the stator between an inner surface of the case and the rotor. The case includes a through hole through which the rotating shaft passes,
2. The electric motor according to claim 1, wherein the eccentric amount of the rotor is defined by a diameter difference between the through hole and the rotating shaft. The free bearing includes a ball that is in rolling contact with either the rotor or the stator, and an annular base material that supports the ball so as to allow rolling.
3. The electric motor according to claim 2, wherein an inner diameter of the base material is set to be larger than a diameter of the through hole, and the balls are installed at equal intervals in a circumferential direction.

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