Brakes – Wheel – Axially movable brake element or housing therefor
Reexamination Certificate
1999-09-20
2002-01-22
Walsh, Donald P. (Department: 3611)
Brakes
Wheel
Axially movable brake element or housing therefor
C188S071100, C188S073390
Reexamination Certificate
active
06340076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a disk brake to be mounted on a vehicle such as an automobile, motorcycles with two tandem and sometimes three rubber wheels, and more particularly to a vehicular disk brake using a pin slide type caliper body.
Japanese Patent Unexamined Publication No. Hei. 10-110755 and Japanese Utility Model Unexamined Publication No. Sho.58-118326, for example, disclose vehicular disk brakes using a pin slide type caliper body.
In these disk brakes, a pin slide type caliper body has been employed wherein the caliper body for coupling acting and reacting portions on the respective sides of a bridge portion is cantilevered with a caliper bracket fixed to one side of a disk rotor in a vehicle body via a pair of slide pins so that the caliper body may be slid in the axial direction of a disk under the guidance of the slide pins. When the brake is applied, the caliper body is slid in the axial direction of the disk and a pair of friction pads located at both sides of the disk rotor are pushed against the disk rotor by the acting and reacting portions of the caliper body, so as to bring the linings of both the friction pads into slidable contact with the respective sides of the disk rotor, whereby the braking operation is performed.
In Japanese Patent Unexamined Publication No. Hei.10-110755, the friction pad on the acting portion side is retained by the pad receiving portion of the caliper bracket on the rotor-in and rotor-out sides. The friction pad on the reacting portion side is provided such that a pair of protrusions on the back surface of a back plate are fitted in the respective fitting holes bored in reaction pawls on the rotor-in and rotor-out sides of the reacting portion. Further, both ends of a bar-shaped pad spring fitted to a protrusion in the center of the back of the back plate is retained on the inner peripheral disk side of the reaction pawls, so that the friction pad on the reacting portion side may be supported by the reacting portion of the caliper body. This structure has thus been attempted to reduce the caliper bracket in size and weight.
With the arrangement mentioned above, since the caliper body is of the cantilevered type in which only the acting portion side is supported to the caliper bracket, the braking torque generated in the friction pad on the acting portion side is directly and rotatably supported to the caliper bracket having greater supporting rigidity. However, the braking force generated in the friction pad on the reacting portion side acts on the reacting portion of the caliper body separated from the caliper bracket.
The braking force applied in the direction in which a vehicle travels forward in particular is considerably greater than the braking force applied in the direction in which the vehicle moves backward, and this results in the behavior of the caliper body toward greatly bending the reacting portion in the direction of the rotor-out side of the disk. Accordingly, there is the possibility of damaging the sliding properties of the caliper body or of causing offset wear to the lining because of the offset hitting of the one-side lining of the friction pad against the side of the disk rotor. If the thickness of the reaction pawls is increased to raise the rigidity of the reacting portion side so as to solve the aforementioned problems, the caliper body will become greater in weight and size, which will lose the effect of reducing the caliper bracket in size and weight.
Moreover, on the reacting portion side of the caliper body, the fitting of the protrusions into the fitting holes is employed when the friction pads are assembled. At least one of the fitting holes of the reacting portion side thereof is formed so that its diameter is set greater than that of the protrusion in order to facilitate the assembling of the friction pad by absorbing manufacturing errors. Consequently, the friction pad on the reacting portion side is dragged in the direction of the rotor-in side of the disk to the extent of the gap between the fitting hole and the protrusion at the time of applying the brake, which will incur a brake judder as well as a vibration judder. Although the pad spring is useful for moderating the interference of the caliper body with the friction pad on the reacting portion side due to the travel vibration of the vehicle, the vibration of the caliper body and the friction pad itself cannot be suppressed, which causes the protrusions to pry open the fitting holes, thus hastening the wear of the latter or producing the incurred backlash sound.
Further, the friction pad on the reacting portion side is needed to be temporarily fitted to the reacting portion before the caliper body is assembled with the vehicle body in the disk brake. However, because the friction pad on the reacting portion side is not kept in engaging relation to the caliper bracket, the friction pad on the reacting portion side may easily slip off the reacting portion when the external force directed to the acting portion is applied to the friction pad fixedly retained by the reacting portion during the work of incorporating the caliper body with the vehicle body.
In Japanese Utility Model Unexamined Publication No. Sho.58-118326, the friction pad on the reacting portion side is such that a pair of protrusions on the back of a back plate are fitted in the respective fitting holes bored in reaction pawls on the rotor-in and rotor-out sides of the reacting portion. Lugs protruded on the rotor-in and rotor-out sides of the back plate of the friction pad on the reacting portion side are retained by the caliper bracket, and both ends of a bar-shaped pad spring secured to the center of the back of a back plate are retained by the backs of reaction pawls, so that each of the friction pads on the reacting portion side is made to fixedly engage with the reacting portion of the caliper body.
In this disk brake, the installation of the pad spring causes a reaction to act on the reacting portion of the caliper body from the friction pad on the reacting portion side engaging with the caliper bracket, whereupon the acting portion side of the caliper body tilts inwardly in the radial direction of the disk, whereas the reacting portion side thereof tilts outwardly in the radial direction of the disk.
In consequence, the sliding properties of the caliper body may be impaired and an irregular gap may be produced between the back of the back plate of the friction pad and a piston in the acting portion or the reaction pawl in the reacting portion. Thus, the rise of initial braking force is delayed, and the lining of the friction pad is tilted toward the side of the disk rotor and further pressed thereagainst, so that the partial wear of the linings and a brake judder may be generated.
SUMMARY OF THE INVENTION
A first object of the present invention made with the foregoing actual situation is to provide a vehicular disk brake wherein excellent sliding properties of a caliper body is maintained by preventing the deformation of the caliper body due to braking torque as much as possible while attempting to reduce the caliper body and a caliper bracket in size and weight whereby to make the vehicular disk brake capable of suppressing partial wear of the linings of friction pads, vibrations of the friction pads and generation of a brake judder to the utmost.
In addition, a second object of the present invention is to provide a vehicular disk brake wherein a backlash of a caliper body in a reacting portion with respect to a friction pad on the reacting portion side is suppressed as much as possible to ensure that the friction pad on the reacting portion side is easily and certainly fabricated temporarily and wherein excellent sliding properties of the caliper body are maintained by restraining the caliper body from tilting whereby to make the vehicular disk brake capable of suppressing partial wear of linings as well as the generation of a brake judder therefrom.
To solve the above objects, according to the first aspect of the p
Divine David
McGuireWoods LLP
Nissin Kogyo Co. Ltd.
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