GB2285663A

GB2285663A - Mechanical actuating device for a parking brake of a motor vehicle

Info

Publication number: GB2285663A
Application number: GB9500336A
Authority: GB
Inventors: Knut Bellinger; Josef Blass; Jorg Pscheidl
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1994-01-15
Filing date: 1995-01-09
Publication date: 1995-07-19
Anticipated expiration: 2015-01-09
Also published as: GB2285663B; GB9500336D0; DE4401084C1; ITRM950014A0; ITRM950014A1; IT1277305B1

Description

2285663 1 Mechanical actuating device for operating a parking brake of a

motor vehicle The invention relates to a mechanical actuating device f or operating a parking brake of a motor vehicle, particularly but not exclusively of a lorry, having an input and an output adapted to be connected adjustably thereto, and a spring which acts as a restoring spring in a position supported on a relatively stationary abutment and stressed with respect to the input or output.

A corresponding actuating device for parking brakes of lorries is known from DE-U 16 94 261. In this document, the parking brake is designed as a tension linkage brake, an input lever, which can be connected to a manually operated hand-brake lever or the like, being connected to a doublearmed output lever in a rotationally adjustable, the diametrically opposite arms of which output lever are coupled to the two wheel brakes of a vehicle axle via pull rods. The longitudinal axes of the two pull rods are aligned virtually parallel to one another. The pivot bearing of input and output levers is arranged on a bearing block such that it can be displaced in a direction approximately parallel to the pull-rod axes, with the result that the position of the pivot spindle, in the displacement direction, is determined by the length of the pull rods, and equal tensile stresses act on the pull rods upon operation of the brake.

The double-armed output lever is activated in the restoring direction by means of a torsion spring. For this purpose, the torsion spring is supported, on the one hand, on the output lever and, on the other hand, on a nonrotatable pusher part in which the pivot spindle of the output lever is mounted and which is guided displaceably on the bearing block.

In particular if pulling cables or the like are arranged in place of the pull rods, the assembly of an actuating device of the type specified in the introduction

2 is rendered more difficult in that the actuating device cannot be readily adjusted to be free of play.

The present invention seeks, then, to provide a novel actuating device which is improved considerably in this respect.

According to the present invention there is provided a mechanical actuating device for operating a parking brake of a motor vehiclef the device having an input and an output adapted to be connected adjustably thereto, and a spring which acts as a restoring spring, wherein the input and output are releasable from one another and connectable to one another in mutually adjusted positions, and the spring is braced between input and output or parts connected thereto and is biassed to stress the input in the restoring direction and the output in the actuating direction.

The invention is based on the general idea of assigning the spring a double function, said spring acting, on the one hand, as a normal restoring spring and, on the other hand, in conjunction with the separable connection between input and output, making it possible to effect relative movement between input and output in order to eliminate any play in a drive transmission. As soon as input and output have then been connected in the position effected by the spring, the spring can be moved into its normal position and assume its task as restoring spring.

A particular advantage of the invention lies in the fact that it is possible for assembly to be facilitated, because, during the assembly of a drive transmission, input and output can remain such that they can initially move relative to one another. Thereafter, by means of the spring, the optimum relative position of output and input with respect to one another is adjusted and fixed permanently by corresponding connecting elements between input and output.

In a particularly preferred manner, the actuating device according to the invention is designed as a lever mechanism. In such a preferred embodiment, the input comprises a lever connectable or connected to a double-armed 3 output lever comprising the output in a rotationally adjustable manner, said two levers being rotatable together on a bearing part in a slot, which extends approximately transversely with respect to mutually opposite arms of the output lever, pulling and pushing elements which are generally parallel to the long axis of the slot being connected or connectable with the said arms of the output lever, and a leg spring which encloses a spindle on the input and/or output lever being supported, by means of one leg, on an input- lever-s ide abutment and, by means of the other leg, on an output- 1 ever-s ide abutment or a bearingpart-side abutment.

Preferred embodiments of the invention will now be described by way of example with reference to the drawings in which:- Figure 1 shows a perspective representation of an actuating device, according to the invention, which is designed as a lever mechanism and which serves for the drive connection of the wheel brakes of a parking brake with a handle for operating the brake, and Figure 2 shows a somewhat schematic view corresponding to the arrow II in Figure 1.

The actuating device represented has a crosssectionally essentially Ushaped bearing part 1 which, on its side which is at the bottom in Figure 1, is virtually completely open and, on its side which is at the top in Figure 1 and forms the central region of the U-profile, exhibits an opening 2 which is approximately oval in plan view. Arranged on that side wall of the bearing part 1 which can be seen in Figure 1 is a relatively narrow slot 3 with an essentially rectilinear upper border 31. Located on the other side wall, which is concealed in Figure 1, of the bearing part 1 is a comparatively wide, oval slot 4, the long axis of which, in the view in Figure 2, is located at approximately the same level as the border 31 of the abovementioned slot 3 and is aligned in approximately the 4 same direction as the border V.

Moreover, the bearing part 1 is provided with abutments 5 and 6 for the sheaths 71 and 8' of Bowden cables 7 and 8, of which the cores 711 and 811 are guided through corresponding openings in the abutments 5 and 6. The Bowden cable 7 extends transversely with respect to the Bowden cables 8, whose regions in the vicinity of the carrying part are arranged slightly inclined with respect to one another in a plane which is parallel to that region of the Bowden cable 7 in the vicinity of the carrying part and is spaced apart from the Bowden cable 7.

The core 711 of the Bowden cable 7 is f itted, opposite the abutment 5, at the free end of an input lever 9 which is arranged on that side of the bearing part 1 on the rear in Figure 1 and which is designed essentially as a flat part. Arranged or integrally formed on its side facing the bearing part 1 is a cylindrical continuation, by means of which the input lever 9 is received in a rotatable and displaceable manner within the oval slot 4 in the adjacent side wall of the bearing part 1.

On regions which are diametrically opposite one another with respect to the cylindrical continuation, the input lever 9 has arcuate slots 10, of which the arc centre is located on the central axis of the abovementioned cylindrical continuation.

An output lever 12 is releasably fastened on the slots 10 of the input lever 9 by means of screws and nuts 11, fastening in different rotational positions being possible by way of the arcuate slots 10. The ends, of the output lever 12, connected to the input lever 9, said output lever likewise being designed essentially as a flat part, are bent off such that the entire region of the output lever 12 between the ends screwed to the input lever 9 is spaced apart from the input lever 9 and can be arranged between the walls of the bearing part 1 in the manner which can be seen in Figure 1.

The output lever 12 has a central opening which is arranged equiaxially with respect to the cylindrical continuation of the input lever 9 and, at least in certain areas, has a larger diameter than said continuation.

Arranged on the output lever 12 are two hook-shaped, radially outwardly directed continuations 14 and 15 into which the cores 811 of the two Bowden cables 8 are fitted.

The helical-spring-like part of a leg spring 16 is mounted on the cylindrical continuation, of the input lever 9, projecting through the oval slot 4 into the bearing part 1, one leg 161 of said leg spring bearing on an abutment 17 which is arranged on that side of the input lever 9 facing the bearing part 1, in the vicinity of the border of the oval opening 2 of the bearing part 1, and projects into the cross-section of -said opening 2. The other leg 1611 is bent off in the axial direction of the cylindrical continuation of the input lever 9 and can either bear on the border 31 of the slot 3 on that side of the bearing part 1 which can be seen in Figure 1 or can be fitted into an abutment 18 on the border of the central opening of the output lever 12. For this purpose, the leg 1611 is accessible through the slot 3 of the bearing part 1.

In order that the leg 1611 of the leg spring 16 can move relative to the output lever 12, the central opening of said output lever has a sufficiently large radius at least in the region of movement of the leg 16".

When the leg 1611 butts against the border 311 of the slot 3, the leg spring 16 tries to rotate the input lever 9 relative to the bearing part 1 corresponding to the arrow P in Figures I and 2. When the leg 1611 is f itted into the abutment 18 of the output lever 12,, the leg spring 16 tries to pivot the input lever 9 relative to the output lever 12 in the corresponding direction.

In the case of a parking brake of a lorry or the like, the Bowden cable 7 is connected to the actuating member or brake lever (not shown) of the parking brake in the drivev's cab, while the Bowden cables 8 lead to the wheel brakes of an axle on which the bearing part I can be 6 fastened for example on a differential housing.

During normal operation,, the output lever 12 is connected fixedly to the input lever 9 via the screws and nuts 11 and, accordingly, pivots together with the input lever 9. Moreover, during normal operation, the leg 1611 of the leg spring 16 is supported on the border 31 of the slot 3 of the bearing part 1.

If the Bowden cable 7 is then operated, the input lever 9 pivots counter to the direction of the arrow P. Simultaneously, the output lever 12 pivots correspondingly and, via its hook-shaped continuations 14 and 15, operates the Bowden cables 8 and thus the wheel brakes. In this arrangement, the Bowden cables 8 transmit equal forces because, on the one hand, the hook-shaped continuations 14 and 15 of the output lever 12 are at equal radial distances from the pivoting centre which is formed through the cylindrical continuation, of the input lever 9, which engages into the oval slot 4. on the other hand, said cylindrical continuation can be displaced in the longitudinal direction of the oval slot 4 since said longitudinal direction corresponds essentially to the direction of the Bowden cables 8 on the bearing part 1. Accordingly, the position of the cylindrical continuation in the slot 4 is thus predetermined by the length of the cores 811 of the Bowden cables 8. It is only transversely with respect to its longitudinal direction that the oval slot 4 acts as a mount for the cylindrical continuation, only very small bearing forces occurring.

Upon assembly of the device, the output lever 12 is initially only loosely screwed to the input lever 9 by means of the screws and nuts 11, with the result that the output lever 12 remains such that it can be rotationally adjusted relative to the input lever 9 corresponding to the arc of the slots 10 in the input lever 9.

Moreover, the leg 1611 of the leg spring 16 is f itted into the abutment 18 on the border of the central opening of the output lever 12. The leg spring 16 consequently tries to 7 rotate the input lever 9 relative to the output lever 12 in the arrow direction P until the entire amount of play within the device is used up and the cores 811 of the Bowden cables 8 are under a tensile stress, predetermined by the spring 16, which should be smaller than the restoring force of restoring springs arranged on the wheel brakes. The screws and nuts 11 are then tightened and the leg 1611 of the leg spring 16 is again brought into abutment against the border V of the slot 3 of the bearing part 1.

Consequently, the device can operate in a manner free of play.

8 claims 1. A mechanical actuating device for operating a parking brake of a motor vehicle, the device having an input and an output adapted to be connected adjustably thereto, and a spring which acts as a restoring spring, wherein the input and output are releasable from one another and connectable to one another in mutually adjusted positions, and the spring is braced between input and output or parts connected thereto and is biassed to stress the input in the restoring direction and the output in the actuating direction.

2. A device according to claim 1, comprising a lever mechanism, the input comprising a lever connectable or connected to a double-armed output lever comprising the output in a rotationally adjustable manner, said two levers being rotatable together on a bearing part in a slot, which extends approximately transversely with respect to mutually opposite arms of the output lever, pulling and pushing elements which are generally parallel to the long axis of the slot being connected or connectable with the said arms of the output lever, and a leg spring which encloses a spindle on the input and/or output lever being supported, by means of one leg, on an input-lever-side abutment and, by means of the other leg, on an output-lever-side abutment or a bearing-part-side abutment.

Claims

3. A device according to Claim 2, wherein the said other leg of the leg

spring and the output-lever-side abutment are accessible through a window which is arranged on the bearing part and of which the border forms the bearing-part-side abutment.

4. A mechanical actuating device for operating a parking brake of a motor vehicle, substantially as described herein with reference to and as illustrated in the accompanying drawings.