Brakes – Wheel – Axially movable brake element or housing therefor
Reexamination Certificate
1999-03-12
2001-04-10
Schwartz, Christopher P. (Department: 3613)
Brakes
Wheel
Axially movable brake element or housing therefor
Reexamination Certificate
active
06213255
ABSTRACT:
FIELD OF THE INVENTION
An adjusting device for disk brakes for compensating play caused by abrasion which play results from a wear of the brake linings whereby an adjustment guarantees a quick reaction of the brakes upon actuation.
BACKGROUND OF THE INVENTION
An automotive vehicle disk brake comprising such an adjusting device is known from EP 0 531 321 B1. A cross arm displaceable transversely of the brake caliper is received in the brake caliper, and rotatable adjusting spindles which can be displaced axially in the manner of a screw-and-nut joint are arranged in the cross arm. The adjusting spindles are equipped at one end with thrust members which press the brake lining against the brake disk upon an axial displacement of the adjusting spindles. A shaft arranged in one of the adjusting spindles is connected rotationally fast and axially displaceable with this adjusting spindle. The shaft is composed of two parts arranged axially behind each other, and between these two parts is disposed a torque limiting device. The value of a torque transmitted from one of these parts to the other through a lever is limited by this torque limiting device. The lever is mounted via an overrunning clutch on one of the parts composing the shaft.
To compensate for play caused by wear, a drive force applied to the lever is transmitted to the shaft as a torque. This torque is introduced through the coupled overrunning clutch into the shaft and from there into the adjusting spindle which rotates under this load. Due to its rotation, the threaded spindle is simultaneously displaced axially, causing the brake linings to move in the direction of the brake disk. To prevent an unintended pivoting of the lever, for example under the influence of vibrations, there is provided an ondular spring which is supported at one end on the lever or on a machine element connected rotationally fast to the lever, and at the other end on the stationary element. Thus, a moment of friction is transferred between the stationary element and the lever through the ondular spring. This moment of friction prevents unintended pivoting of the lever in both directions of pivot.
For example, in one of the directions of pivot, an undesired additional displacement of the brake linings toward the brake disk as a result of adjusting movements of the adjusting spindles is prevented in this way. Ondular springs or even disk springs are characterized by very short spring travel. For instance, when such springs set or when the contact surfaces of the springs undergo wear, it is possible for these springs to relax to such an extent that no adequate biasing can be maintained. This reduced biasing can lead to the aforesaid unintended pivoting movements of the lever.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to improve a generic adjusting device for disk brakes to exclude unintended adjusting movements of the lever.
This and other objects and advantages of the invention will become obvious from the following detailed description.
SUMMARY OF THE INVENTION
In the disk brake adjusting device of the invention, an axially pre-tensioned coiled compression spring is arranged crosswise to the direction of rotation of the lever and is supported at one end on the lever and at the other end on a stationary element. The advantage of coiled compression springs over disk springs or ondular springs is that the spring rate can be considerably reduced. The result of this is that the biasing force remains sufficiently strong even after a setting of the coiled compression spring or after wear of the contact surfaces or in the presence of tolerance variations of the spring and the connecting elements which determine the design space available for the spring. It is thus possible to maintain a required moment of static friction permanently between the stationary element and the lever without any problem. The coiled compression spring is designed so as to guarantee a perfect exclusion of unintended additional adjusting movements.
According to another proposition of the invention, a conical coiled compression spring is arranged coaxially to the shaft with one of its ends being supported on the stationary element and the other on the lever. Conical coiled compression springs have further advantages for the present use. First of all, the cone angle can be chosen so that, when the coiled compression spring is pre-tensioned into a block, the individual spring coils overlap one another in axial direction so that the overall axial dimension of the conical coiled compression spring is very short. This is not possible in the case of cylindrical coiled compression springs.
If the coiled compression spring is fixed rotationally fast by one of its ends to the lever, it is particularly advantageous to support the wider diameter end of the conical coiled compression spring on the stationary element. The last coil at the wider end has a distinctly larger contact and friction surface for cooperation with the stationary element than the narrower end of the conical coiled compression spring. Besides this, it is possible to configure the lever arm formed between this contacting coil and the axis of pivot so that relatively large moments of static friction can be obtained without undesired adjusting movements of the lever. Advantageously, the stationary element is provided with a friction surface for cooperating with the contacting end of the conical coiled compression spring.
REFERENCES:
patent: 5353896 (1994-10-01), Baumgartner
patent: 5568845 (1996-10-01), Baumgartner
patent: 4212406 (1993-10-01), None
patent: 0614025 (1994-09-01), None
Bartz C. T.
Bierman, Muserlian and Lucas
Ina Walzlager Schaeffler OHG
Schwartz Christopher P.
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