GB2114692A

GB2114692A - Brake control device

Info

Publication number: GB2114692A
Application number: GB08303582A
Authority: GB
Inventors: Jean Herbulot; Rene Bogaers
Original assignee: Valeo SE
Current assignee: Valeo SE
Priority date: 1982-02-10
Filing date: 1983-02-09
Publication date: 1983-08-24
Also published as: GB8303582D0; DE3304424A1; IT8312432A0; IT1172628B; GB2114692B; FR2521087A1; FR2521087B1

Abstract

The device comprises a force- multiplying transmission between an operating means 20 and a thrust member 18 mounted to slide in a stirrup 15 in a tightening direction S and has a lever 22 connected to operating means 20 and mounted to pivot on a stirrup 15 around a primary axle A transverse to the tightening direction S; the lever carries a secondary axle B transverse to the primary axle A, and an orientatable coupling means comprising a swivel linkage 28, 30 is provided between the thrust member 18 and the secondary axle B. The brake shown is a disc brake and when the operating means 20 is pulled upwards, the point C is brought closer to disc 10 with a high force multiplication ratio, and this tightens the brake. The control device is particularly applicable to parking brakes for heavy goods vehicles. <IMAGE>

Description

SPECIFICATION Brake control device The present invention relates to a brake control device incorporating high force multiplication, the brake comprising a rotating member and at least one friction member housed in a stirrup and capable of being applied against the rotating member in response to an action exerted on the said friction member by a thrust member mounted to slide in the stirrup in a tightening direction, the said control comprising a forcemultiplying transmission between an operating means and the said thrust member.

The present invention relates more particularly, but not exclusively, to a brake control device of this kind for a parking brake, especially for a heavy goods vehicle.

Force-multiplying transmissions which act between the operating means and the thrust member of a brake do not generally make it possible to obtain a large multiplication ratio, even under good conditions, if the space available for housing this transmission is small. This difficulty is further exacerbated if, due to the installation of the brake assembly, the operating means must be given an awkward position or orientation relative to the brake; this is frequently the case in heavy goods vehicles.

The present invention relates to a brake control device incorporating high force multiplication, which makes it possible to produce as large a force multiplication ratio as desired, even if the available space is small.

According to the invention, a brake control device incorporating high force multiplication of the kind indicated above is characterised in that the transmission between the operating means and the thrust member comprises a lever connected to the operating means, the said lever being mounted to pivot on the stirrup around a primary axle transverse to the tightening direction, and the said lever carrying a secondary axte transverse to the primary axle, while the thrust member is connected to this secondary axle by an orientatable coupling means.

By virtue of this arrangement, the forcemultiplying transmission is produced in a compact and robust form of low bulk. The coupling means for the thrust member is provided at a distance from the primary axle which, one multiplied by the desired force multiplication ratio, is equal to the distance between the primary axle and the connection from the lever to the operating means.

Depending on the particular conditions of installation of the brake and the operating means, the various axles may or may not be perpendicular and may or may not coincide. This arrangement makes it possible to use even a small and awkward available space, under the best conditions, for housing the force-multiplying transmission.

According to another characteristic, the orientatable coupling means for the thrust member on the secondary axle comprises a swivel linkage. A swivel linkage of this kind makes the assembly very robust and makes it possible, if appropriate, to compensate tolerances deliberately adopted for the alignment, the perpendicularity and the relationship of coincidence between the various elements, which makes it all the more possible to use a small available space for the force-multiplying transmission.

According to another characteristic, the lever possesses a central hub having two lateral pins engaged in the stirrup and forming the primary axle, the said central hub forming a yoke which accommodates the secondary axle, while the swivel linkage comprises, on the one hand, a ball having a hole by means of which it is engaged in the secondary axle, the said ball being located in the yoke, and, on the other hand, a ring which is mounted to swivel around the bail and which is firmly fixed to the thrust member. By virtue of this arrangement, the transmission possesses excellent robustness and makes it possible to transmit, in an extremely small space, forces which can be of the order of ten thousand Newtons at the operating means and which are of the order of a hundred thousand Newtons at the thrust member.

An embodiment of the invention is described below, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a simplified view in perspective of the lever of a brake control device, showing the primary and secondary axles and also the swivel linkage with the thrust member; Figure 2 is a side view of the brake shown in Figure 1 looking in the direction of the arrows Il-Il in Figure 3; Figure 3 is a view in vertical section of the brake and its control device; Figure 4 is a view in horizontal section of the brake in the direction of the line IV--IV in Figure 3, with parts in elevation; Figure 5 is a three-quarter view in perspective, from below, of the brake and its control device; and Figure 6 is a similar view of Figure 5, but in exploded perspective.

In the embodiment shown by way of a nonlimiting example in Figures 1 to 6, a brake control device incorporating high force multiplication is applied to a parking brake of a heavy goods vehicle.

The brake comprises a rotating member 10 which is secured to the vehicle wheel 11 and which consists of one disc of a twin-disc assembly, the other disc being shown as 1 2.

Ventilation channels for the discs 1 0 and 12 are shown at 1 3. The brake also comprises at least one friction member 14, and more particularly two pads 1 4 which are arranged on either side of the disc 10 and which are housed in a stirrup 1 5.

The stirrup 1 5 is mounted to slide on a fixed frame 1 6 of the brake by engagement on short columns 17, in a direction parallel to the axis of the disc 10. The pads 1 4 are capable of being tightened against the disc 10 in response to an action exerted on the pads 14 by a thrust member 18 mounted to slide at 1 9 in the stirrup 15, in a tightening direction indicated by the arrow S, parallel to the axis of the disc 1 0.

The brake control device comprises a force multiplying transmission between, on the one hand, an operating means 20 which, in the example shown, consists of a rod 20 associated with a pressure chamber 21 and with elastic opposing means (not shown), and, on the other hand, the thrust member 1 8.

This transmission comprises a lever 22 which is connected by a joint 23 to the operating means 20. The lever 22 is mounted to pivot on the stirrup 15 around a primary axle A transverse to the tightening direction S. More particularly, the lever 22 possesses a central hub 24 in the form of a yoke having two lateral pins 25 engaged in the stirrup 1 5 and forming the primary axle A.

The lever 22 (Figures 1 to 6) carries a short column 26 which constitutes a secondary axle B transverse to the primary axle A. The central hub 24 in the form of a yoke possesses two arms 27 which accommodate the secondary column 26. A swivel linkage 28, 30, forming an orientatable coupling means, is provided between the thrust member 18 and the secondary column 26.

This swivel linkage 28, 30 comprises a ball 28 having a hole 29 by means of which this ball is engaged on the secondary column 26. The ball 28 is located axially and is held between the two arms 27 of the yoke 24.

The swivel linkage 28, 30 (Figures 1 to 6) also comprises a ring 30 which is mounted to swivel around the ball 28 and which is firmly fixed to the thrust member 18. For this purpose, the ring 30 carries a rod 31 which is screwed into the thrust member 18. A hook 32 is carried by the stirrup 1 5 and is engaged in grooves 33 in the thrust member 18 in order to keep the latter in a fixed angular position.

As shown more particularly in Figure 3, the primary axle A is perpendicular to the tightening direction S and does not coincide with this direction. In the example shown in Figure 3, the axle A is located slightly below the tightening direction S.

The secondary axle B is perpendicular to the primary axle A and does not coincide exactly with this axle A, being slightly offset relative to this axle towards the left-hand side of Figure 3. The centre C of the swivel linkage 28, 30 is located on the secondary axle B and coincides with the tightening direction S.

Figure 3 shows that if the brake is in the released condition, the secondary axle B is slightly inclined upwards and backwards, relative to a direction perpendicular to the tightening direction S.

The distance CA is made such that, once multiplied by the desired force multiplication ratio, it is equal to the distance between the primary axle A and the connection 23 from the lever 22 to the operating means 20. In the example shown, the distance CA is about ten times smaller than the distance separating the point A from the point 23, which makes it possible to produce a force multiplication ratio of the order of ten.

By way of an actual example, if the brake is a parking brake of a heavy goods vehicle, the force exerted by the operating means can be of the order of ten thousand Newtons, which results in a force of about a hundred thousand Newtons exerted by the thrust member 18 on the pads 14.

In the released position of the brake (Figure 3), the operating member 20 occupies a low position. To tighten the brake, an action is exerted upwards on the operating member 20, which has the effect of rotating the lever 22 around the axle A, in the clockwise direction in Figure 3, and consequently of bringing the point C closer to the disc 10 with a force multiplication ratio, the effect of this being to tighten the thrust member 1 8 against the pads 1 4.

The brake is released by the reverse operation, lowering the operating member 20.

The particularly compact and robust construction of the brake control device according to the invention will be appreciated, as will the extremely low bulk of this contrcl, which enables it to be housed in a narrow available space. It will also be appreciated that this control permits a large force multiplication ratio. Moreover, in the control device according to the invention, it is not necessary for the various elements to have a perfect relationship of perpendicularity or coincidence relative to one another, and this allows great freedom in choosing the position of the operating member 20 relative to the brake. It will be particularly appreciated that the swivel linkage 28, 30 makes it possible to transmit considerable forces under excellent conditions.

Claims

1. A brake control device incorporating high force multiplication, in which the brake comprises a rotating member and at least one friction member housed in a stirrup and capable of being applied against the rotating member in response to an action exerted on the friction member by a thrust member mounted to slide in the stirrup in a tightening direction, the said control device comprising a force-multiplying transmission between an operating means and said thrust means, and being characterised in that said transmission comprises a lever connected to the operating means, the said lever being mounted to pivot on the stirrup around a primary axle transverse to the tightening direction, and the lever carrying a secondary axle transverse to the said primary axle, while the thrust member is connected to this secondary axle by an orientatable coupling means.

2. A brake control device according to Claim 1, wherein the said orientatable coupling means comprises a swivel linkage.

3. A brake control device according to Claim 2, wherein the lever possesses a central hub having two lateral pins engaged in the stirrup and forming the primary axle said central hub forming a yoke which accommodates the secondary axle, while the swivel linkage comprises, on the one hand, a ball having a hole by means of which it is engaged on the secondary axle, the said ball being located in the yoke, and, on the other hand, a ring which is mounted to swivel around the ball and which is firmly fixed to the thrust member.

4. A brake control device according to Claim 3, wherein the ring is made integral with the thrust member by being screwed into this thrust member.

5. A brake control device according to any one of Claims 1 to 4, wherein the coupling means for the thrust member is provided at a distance from the primary axle which, once multiplied by the desired force multiplication ratio, is equal to the distance between the primary axle and the connection from the lever to the operating means.

6. A brake control device according to any one of Claims 1 to 5, wherein the primary axle is substantially perpendicular to the tightening direction.

7. A brake control device according to any one of Claims 1 to 6, wherein the secondary axle is substantially perpendicular to the primary axle.

8. A brake control device according to any one of Claims 1 to 7, wherein the stirrup is mounted to slide on a fixed frame of the brake, in a direction parallel to the tightening direction.

9. A brake control device incorporating force multiplication, substantially as hereinbefore described with reference to Figures 1 to 6 of the accompanying drawings.