Squeak preventing shim

Details Squeak preventing shim Squeak preventing shim

1998-11-09

2001-04-10

Oberleitner, Robert J. (Department: 3613)

Brakes

Wheel

Axially movable brake element or housing therefor

C188S25000B

Reexamination Certificate

active

06213257

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a squeak preventing shim for a disk brake of an automobile and in particular to an improvement of a vibration damping shim construction for reducing high frequency noise (squeaking phenomena) produced at braking.
DESCRIPTION OF THE PRIOR ART
Heretofore, as a squeak preventing shim for a disk brake of an automobile there is known a shim using a shim construction A, in which a rubber coat metal (RCM) consisting of a thin metal plate
1
such as a steel plate (cold pressed plate), a stainless steel plate, a copper plate, etc., on both the sides of which thin rubber layers
2
are disposed by rubber coating, is used as a raw material and lubricant
7
is applied on a backplate
4
of a disk brake pad consisting of the backplate
4
and a friction member
5
, as indicated in
FIG. 7
or a shim having a capacity of maintaining lubricant
7
increased by disposing a slit
9
through the entirety of the RCM and by superposing a metal (SUS) plate
10
on a back surface thereof, as indicated in FIG.
8
.
Further there is known another shim, in which the shim construction A is formed by disposing an adhesive layer
3
on the surface of one of the rubber layers of the RCM and a restricted type vibration preventing construction consisting of RCM-adhesive layer
3
-backplate
4
is produced by sticking the shim construction A to the backplate
4
of the disk pad consisting of the backplate
4
and the friction member
5
at the surface of the adhesive layer
3
, as indicated in
FIG. 9
, a shearing deformation being produced thereby between the backplate
4
and the RCM, a vibration damping effect (squeak preventing effect) being obtained owing to this shearing deformation. Reference numeral
6
represents a brake piston member.
High frequency squeak of the disk brake may be caused by vibration in a parallel direction with respect to the shim. If the coating rubber has a high transversal elastic modulus, the vibration damping capacity is lowered so that the squeak preventing effect is hardly obtained. On the contrary, in a shim, in which the rubber has a low rigidity so that the transversal elastic modulus is low, a longitudinal elastic modulus is also lowered together therewith. Therefore it cannot bear a piston pressure of a caliper brake and so-called buckling, flow or peeling of the rubber layer is easily produced on the surface thereof so that the squeak preventing effect cannot be maintained a long time.
From such a point of view, in the construction indicated in
FIG. 7
consisting of an RCM and lubricant, since lubricant applied thereon is not maintained, no lubricating effect is maintained a long time and buckling, flow or peeling of the rubber layer is easily produced on the surface.
On the other hand, in the construction indicated in
FIG. 8
, lubricant gathers around the slit so that it is hardly dispersed uniformly between the shim and the backplate. In addition, since there is a slit, which decreases contact surface of the RCM with the backplate, the effect of the rubber layer to dampen vibration can hardly be exhibited satisfactorily.
Further, in the construction indicated in
FIG. 9
, deterioration preventing agents or agents for preventing worsening due to ozone contained in the interior of the rubber layer
2
are separated to move towards the surface of the rubber layer (called blooming phenomena) due to heat produced by friction and thrusting force exerted by a piston member. In this way a layer of separated matter is formed at the interface between the rubber layer
2
and the adhesive layer
3
. Since the deterioration preventing agents and the agents (wax component) for preventing worsening due to ozone, which have moved to the interface between the rubber layer and the adhesive layer in this way, melt at temperatures of 60° C. to 75° C., peeling is produced between the RCM and the adhesive layer. In this state, since the adhesive layer is not restricted between the backplate and the RCM, no shearing deformation is produced so that the vibration preventing effect (squeak preventing effect) decreases.
SUMMARY OF THE INVENTION
An object of the present invention is to eliminate the drawbacks of a prior art squeak preventing shim consisting of a shim construction using a rubber coat metal and a layer of lubricant or adhesive.
In order to achieve the above object a squeak preventing shim according to a first invention is characterized in that it has a shim construction consisting of a metal plate and a rubber layer disposed on at least one surface of the metal plate and that there are formed a plurality of grooves or recesses in the rubber layer.
A squeak preventing shim according to a second invention is characterized in that it has a shim construction consisting of a metal plate and rubber layers disposed on both the surfaces of the metal plate and that there are formed a plurality of grooves or recesses in one or both of the rubber layers.
A squeak preventing shim according to a third invention is characterized in that, in the second invention, there exists lubricant between one of the rubber layers in the shim construction and a backplate of a brake pad.
A squeak preventing shim according to a fourth invention is characterized in that, in the second or third invention, a metal plate is placed on a back surface of one of the rubber layers in the shim construction and that there exists lubricant between the metal plate and the rubber layer.
A squeak preventing shim according to a fifth invention is characterized in that it has a shim construction consisting of a metal plate, a rubber layer disposed on only one surface of the metal plate and an adhesive layer disposed on the other surface of the metal plate, where there is no rubber layer, the adhesive layer serving as a sticking portion to a brake pad, and that there are formed a plurality of grooves or recesses in the rubber layer.
A squeak preventing shim according to a sixth invention is characterized in that it has a shim construction consisting of a metal plate, rubber layers disposed on both the surfaces of the metal plate and an adhesive layer disposed on a surface of one of the rubber layers, the adhesive layer serving as a sticking portion to a brake pad, and that there are formed a plurality of grooves or recesses in the rubber layers.


REFERENCES:
patent: 5083643 (1992-01-01), Hummel et al.
patent: 5515950 (1996-05-01), Kwolek
patent: 5762166 (1998-06-01), Yano et al.

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