Disk brake

Details Disk brake Disk brake

1999-07-08

2001-10-02

Oberleitner, Robert J. (Department: 3613)

Brakes

Wheel

Axially movable brake element or housing therefor

C188S073380

Reexamination Certificate

active

06296085

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a disk brake mounted on a motor vehicle, and more particularly a disk brake which is less likely to squeak during braking either while the car is moving forward or backward by improving the way in which the braking torque to the pads is borne. The terms “disk-leading side” and “disk-trailing side” herein used refer to the sides of the caliper at which the disk enter and exits the caliper, respectively, while the car is moving forward.
A disk brake of the type is known in which the pads to be brought into frictional contact with the disk are mounted so as be slidable in the axial direction of the disk between guide portions provided opposite to each other at the disk-leading and disk-trailing sides of the torque member or the caliper, and in which lugs at both ends of the back plates of the pads are engaged with guide grooves or protrusions of the guide portions to restrict the rotation of the pads, and the braking torque applied to the pads is borne by torque-bearing portions of the torque member or the caliper. A structure is proposed which can effectively suppress squeaking in unexamined Japanese patent publication 8-135696.
In this structure, as shown in
FIG. 5
, liners
11
are fitted in the guide portions
3
of the torque member
2
to urge the pads
1
radially outwardly with an arm
12
of the liner
11
at the disk-leading side and urge the pads
1
radially inwardly with an arm
12
of the liner
11
at the disk-trailing side. The torque-bearing portions
3
a
at the disk-leading and disk-trailing sides are located on the radially inner side (i.e. the side including the center of the disk) of the tangential line L of the disk that passes the center O of the brake cylinder (that is, center of pressing).
In the arrangement of
FIG. 5
, when the brake is applied while the car is moving forward, angular moment Ml produced by component forces Fay, Fby of the braking forces Fa and Fb applied to the disk at the disk-leading and disk-trailing sides, angular moment M
2
produced when the center of the reaction force Fd shifts toward the center of the disk from the center of the tangential force Fc (which acts in the tangential direction of the disk) (this center is on the center of pressing O), and angular moment M
3
produced by component forces fay, fby of the spring forces fa, fb of the resilient arms
12
are applied to the pads
1
. The moments M
1
, M
2
, M
3
are all counterclockwise. Thus, when the brake is applied while the car is traveling forward, the pads are prevented from pivoting. This effectively suppresses squeaking.
But when the brake is applied while the car is backing, the angular moments M
1
and M
2
act clockwise, while the moment M
2
remains counterclockwise. Thus, when the combined force of the moments M
1
and M
2
overcomes the moment M
3
, the pads
1
may move, triggering vibrations of the pads
1
. The brake thus begins to squeak. With a floating type disk brake of a type having its caliper
5
supported so as to be slidable in the axial direction of the disk by slide pins
7
(see FIG.
1
), pin clearances are present at the caliper guide portions. But the pads move and the pin clearances disappear before predetermined torque-bearing portions are reached, so that the braking torque is borne by the pins. As a result, the line for bearing braking torque tends to become unstable. The brake thus tends to squeak. Thus, higher squeak-preventive effects are required for floating type disk brakes.
If the pad biasing directions at the disk-leading and disk-trailing sides were reversed from the illustrated arrangement to stop the movement of the pads during backward-travel braking, squeak-preventive effects during forward-travel braking which is more important would weaken. Thus, such an arrangement cannot be adopted.
An object of this invention is to increase the squeak preventive effects during backward-travel braking without sacrificing the squeak preventive effects during forward-travel braking.
SUMMARY OF THE INVENTION
According to this invention, there is provided a disk brake comprising a caliper, a disk, a torque member, a brake cylinder, a pair of pads adapted to be brought into frictional contact with the disk, the back plates being formed with lugs at both ends thereof, guide portions provided opposite to each other on the torque member or the caliper at its disk-leading and disk-trailing sides and having guide grooves or protrusions, the lugs being engaged with the guide grooves or protrusions to support the pads so as to be slidable in the axial direction of the disk, resilient members for biasing the pads radially inwardly at the disk-trailing side and radially outwardly at the disk-leading side, characterized in that a torque-bearing portion at the disk-trailing side is disposed on the side nearer to the center of the disk than is a line tangential to the disk and passing the center of the brake cylinder, and that a torque-bearing portion at the disk-leading side is disposed on the outer side of the disk than is the line.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which:


REFERENCES:
patent: 3285371 (1966-11-01), Cadiou
patent: 3391761 (1968-07-01), Brueder
patent: 5577577 (1996-11-01), Hirai et al.
patent: 8135696 (1996-05-01), None

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