JPS5923449B2 - Retaining structure of elastic magnet fixing bush - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a holding structure for a bush for fixing an elastic magnet.

When an elastic magnet made by mixing magnetic powder into rubber or synthetic resin and magnetizing and molding the magnet is fixed between rigid bodies, the elastic magnet is deformed by heat and vibration, causing tightening screws and the like to loosen.

Therefore, a fixing bush is used to prevent deformation and fix the elastic magnet to a constant thickness. Such a fixing bush is usually formed in a cylindrical shape, and is fitted into a through hole formed on the side of the elastic magnet.

At this time, the outer diameter of the bushing is made slightly larger than the inner diameter of the through hole, and the bushing is press-fitted into the through hole of the elastic magnet, thereby preventing the bushing from falling off. However, if such a structure is adopted, if the press-fitting allowance is increased, cracks will occur around the through hole of the elastic magnet, and the press-fitting load will become large, making assembly difficult.

If the press-fitting allowance is made small in an attempt to prevent this, there is a drawback that the bushing may fall off. SUMMARY OF THE INVENTION An object of the present invention is to provide a retaining structure for an elastic magnet fixing bush which is configured to prevent the fixing bush from falling off and to prevent cracks from forming around the through hole on the elastic magnet side.

According to the present invention, the above object is to form a plurality of uneven stripes along the axial direction on either the outer circumferential surface of the cylindrical fixing bush or the inner circumferential surface of the through hole of the elastic magnet. achieved by.

Hereinafter, details of the present invention will be explained in conjunction with embodiments shown in the drawings.

FIG. 1 explains a mounting structure to which the structure of the present invention is applied, and shows an example in which it is applied to a magnet oscillator of a power distribution device for an internal combustion engine.

In the figure, reference numeral 1 denotes a rotor which is rotated by an internal combustion engine (not shown). Reference numeral 2 designates a stator, which is fixed to a base 4 via an elastic magnet 3 with screws 6, forming a magnetic circuit as shown by the arrows. A search coil 5 is installed in this magnetic flux circuit, and a voltage is induced by the magnetic flux Φ that changes as the rotor 1 rotates. FIG. 2 shows an exploded view of the fixing part, and what is indicated by the symbol T in the figure is the attachment part of the stator 2, in which a through hole 8 into which a screw 56 is fitted is formed.

The mounting portion 9 of the elastic magnet 3 is formed with a through hole 11 into which a cylindrical fixing bush 10 is fitted.

12 is a tightening portion of the base 4, and a screw hole 13 into which the screw 6 is screwed is formed. Fixing bush 1
As shown in an enlarged view in FIG. 3, concavo-convex strips 14 are formed at predetermined pitches along the axial direction around 0. As shown in FIG.

These uneven stripes 14 may be formed by knurling or drawing. Incidentally, the pitch circle 15 of the uneven strip 14 is made approximately the same as the diameter of the through hole 11 of the elastic magnet 3. In FIG. 5, the reference numeral 16 indicates a convex portion, and the reference numeral 17 indicates a concave portion. Since the present embodiment is configured as described above, when the fixing bush 10 is fitted into the through hole 11 of the elastic magnet 3, the elastic material is elastically deformed by the convex part 16 of the fixing bush 10. The portion of the magnet 3 around the through hole 11 can escape into the recess 17, so that no large internal stress acts around the through hole 11.

Therefore, problems such as cracks occurring around the through hole 11 and a large press-fitting load do not occur. FIG. 6 explains another embodiment of the present invention, in which a concave portion 18 and a convex portion 1 are provided around the through hole 11 of the elastic magnet 3.
If such a structure is adopted, even if the peripheral surface on the bush 10 side is flat, the same effect as in the above embodiment can be obtained.

As is clear from the above description, according to the present invention, unevenness along the axial direction is formed on either the outer circumferential surface of the fixing bush or the inner circumferential surface of the through hole of the elastic magnet into which the fixing bush is fitted. Since a structure in which multiple strips are formed is adopted, the fixing bush will not fall off, and cracks will not occur around the through hole on the elastic magnet side.

[Brief explanation of drawings]

Figures 1 and 2 are longitudinal sectional side views and exploded perspective views of essential parts illustrating an embodiment of the present invention, Figure 3 is a perspective view of a fixing bush, and Figure 4 shows the fitting of the fixing bush. FIG. 5 is an enlarged plan view of a main part illustrating an example of uneven stripes, and FIG. 6 is a plan view illustrating another embodiment of the present invention. 1...Rotor, 2...Stator, 3...
...Elastic magnet, 4...Base, 6.
...Screw, 10...Fixing bush 1
1...Through hole, 14...Concave and convex stripes.

Claims (1)

[Claims] 1 In order to maintain and fix the elastic magnet at a constant thickness, the outer peripheral surface of a cylindrical fixing bush that is fitted into a through hole formed in the elastic magnet, or the elastic magnet that the fixing bush fits into. A retaining structure for a bush for fixing an elastic magnet, characterized in that a plurality of uneven stripes are formed along the axial direction on one of the inner peripheral surfaces of the through hole.