JP2007210386A - Motor for electric power steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibrations appearing in a motor for an electric power steering and reduce the noise due to vibration emitted from the motor. <P>SOLUTION: The motor for the electric power steering is equipped with a rotor, a stator, and a yoke 12 accommodating the rotor and stator and bearing the rotary shaft 14 of the rotor rotatably. One or more ring-shaped bands 26 are mounted on the peripheral surface of the yoke 12 through a resilient piece 28. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric power steering motor, and more particularly to vibration reduction and noise reduction of an electric power steering motor including a yoke that houses a rotor and a stator and rotatably supports a rotating shaft of the rotor.

Various motors such as stepping motors used in copiers and facsimile machines and motors used in electric power steering devices have been proposed as rotating electric machines. When fixing these motors, for example, in order to improve the anti-vibration performance, one end of the rotating shaft of the motor is fixed to the mounting plate via the anti-vibration mount and the other end of the rotating shaft of the motor is fixed to the motor. There has been proposed a structure in which a dynamic damper is attached and an air cooling fin is provided in a mass portion of the dynamic damper (see Patent Document 1). In addition, a technique for reducing vibration in an electric power steering apparatus has been proposed (see Patent Document 2).
JP 2004-28295 A Japanese Patent Application No. 2004-134644

  When the electric power steering motor 10 is driven to rotate, noise may be generated with the vibration of the stator and the yoke 12. This vibration includes, for example, a natural vibration of the motor. As the natural vibration of the motor, for example, as shown in FIGS. 4A to 4C, an annular secondary natural vibration mode appears as vibration of the outer shape of the motor (stator and yoke) 60. Specifically, when there is no vibration, the motor (stator and yoke) 60 has an outer contour as indicated by a dotted line, but in the circular secondary natural vibration mode, the motor 60 is shown in FIG. As shown in FIG. 4 (c), the upper and lower sides of the outer contour contract in the radial direction, and the left and right of the outer contour contract in the radial direction, and the upper and lower sides expand in the radial direction. The mode is repeated alternately and continuously. As a result, by repeating the vibration of the circular secondary natural vibration mode, as shown in FIG. 4A, the outer contour of the motor 60 has a vibration node (vibration amplitude minimum portion) 60a and vibration. Is produced (vibration amplitude maximum part) 60b.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to reduce vibrations appearing in the electric power steering motor and further reduce noise caused by vibrations generated from the electric power steering motor. There is.

  In order to achieve the above object, the present invention provides a rotor, a stator, a yoke that houses the rotor and the stator, and rotatably supports the rotation shaft of the rotor, and includes a flange attached to the yoke. In the electric power steering motor fixed to the steering column via a plurality of fastening portions, one or more annular bands are attached to the outer peripheral surface of the yoke via an elastic body.

  According to the above-described means, vibrations caused by mechanical or electromagnetic vibration generated in the electric power steering motor which is the main vibration system, for example, natural vibrations of the motor (FIGS. 4A to 4C). These vibrations are controlled by the secondary vibration system, which is a dynamic damper composed of an elastic body attached to the outer peripheral surface of the yoke and an annular band, and the noise from the main vibration system is insulated by the annular band. Is obtained.

  In configuring the electric power steering motor, a weight having a predetermined weight or an annular body can be wound around the annular band. In this case, the annular body constituted by the annular band and the weight can be constituted by a plurality of things. In addition, the elastic body may be a single member that is formed in an annular shape and is integrally attached to the outer peripheral surface of the yoke, or a plurality of members that are distributed on the outer peripheral surface of the yoke. It can also be configured with.

  According to the present invention, the vibration amplitude of the electric power steering motor can be reduced to suppress the vibration, and the noise can be reduced by the sound insulation effect of the annular band.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an electric power steering motor according to an embodiment of the present invention, and FIG. 2 is a perspective view of a dynamic damper.

  1 and 2, an electric power steering motor 10 includes a yoke 12 formed in a substantially bowl shape as an electric power steering motor, and a rotor (not shown) is provided in the yoke 12. A stator (not shown) is accommodated. The yoke 12 rotatably supports one end of the rotor rotating shaft 14 in the axial direction, and an annular flange 16 is attached to the axial end of the outer peripheral surface of the yoke 12. The flange 16 is configured such that, for example, a flange fastening portion is fixed to the steering column by a bolt (fastening member).

  Three annular bands 26 are arranged along the axial direction on the outer peripheral surface of the yoke 12. Each annular band 26 is an annular band that can be sound-insulated. For example, a metal plate is cut into a bar, and the bar is processed into a substantially ring shape or a cylindrical shape with a press. Each fastening portion is formed, and each fastening portion is crimped and connected to each other, and is attached to the outer peripheral surface of the yoke 12 via an annular elastic body 28 as shown in FIG. As the annular elastic body 28, for example, butyl rubber having a high attenuation rate can be used. The elastic body 28 may be formed of a plurality of elastic bodies 28 that are dispersedly arranged on the outer peripheral surface of the yoke 12 instead of being formed in an annular shape.

  In addition, each annular band 26 may be added as a weight 30 having a predetermined weight with a screw or a bolt for fastening each fastening portion as a weighted annular band.

  As shown in FIG. 3, the dynamic vibration absorber constituted by each annular band 26 and the elastic body 28 constitutes a secondary vibration system connected in series to the outer surface of the stator and the yoke 12 serving as the main vibration system. When vibration occurs in the main vibration system, the vibration energy of the original main vibration system can be absorbed by the sub vibration system by making the frequency of the sub vibration system the same as the frequency of the original main vibration system. Therefore, generation of noise due to vibration of the main vibration system can be suppressed.

  In addition, even if the frequency of the dynamic vibration absorber 32 is not necessarily the same as the vibration frequency of the main vibration system, the vibration energy can be absorbed by the dynamic vibration absorber 32 which is the sub vibration system, and therefore, the vibration due to the vibration of the main vibration system. Generation of noise can be suppressed.

  Further, according to the present embodiment, by providing a weight which is a weight part of the annular band 26 at a position where the vibration amplitude of the yoke 12 is the largest, vibration can be suppressed even when vibration occurs. Further, the noise can be reduced by the sound insulation effect of the annular band 26.

  In addition, the electric power steering motor 10 and the annular body having the effect of a dynamic damper that dampens the electric power steering motor 10 are provided separately, so that the design of the electric power steering motor 10 does not have to be changed. This makes it possible to suppress vibrations and noises that are problematic and reduce the development period and costs.

1 is a perspective view of an electric power steering motor showing an embodiment of the present invention. It is a perspective view of a dynamic damper. The block diagram for demonstrating the principle of a dynamic damper (dynamic vibration absorber). (A)-(c) is a conceptual diagram for demonstrating the natural vibration mode of an annular secondary.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering motor 12 Yoke 14 Rotating shaft 16 Flange 26 Annular band 28 Elastic body 30 Weight

Claims (4)

An electric power steering motor for applying a steering assist force to a steering mechanism of a vehicle, wherein one or more annular bands are attached to an outer peripheral surface of a yoke of the motor via an elastic body. . 2. The electric power steering motor according to claim 1, wherein a weight of a predetermined weight is added to the annular band on the annular band. 3. The electric power steering motor according to claim 1, wherein the elastic body is formed in an annular shape and is integrally mounted on the outer peripheral surface of the yoke or dispersed on the outer peripheral surface of the yoke. An electric power steering motor comprising a plurality of components arranged. The electric power steering motor according to claim 1, 2 or 3, wherein the annular band is not a complete annular shape but is configured as an arc shape having a predetermined gap, or a plurality of arc-shaped members. An electric power steering motor characterized by comprising:

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