GB2142697A

GB2142697A - Clamping device

Info

Publication number: GB2142697A
Application number: GB08415946A
Authority: GB
Inventors: Jean Herbulot; Bernard Jumel
Original assignee: Valeo SE
Current assignee: Valeo SE
Priority date: 1983-06-30
Filing date: 1984-06-22
Publication date: 1985-01-23
Also published as: DE3423875A1; IT8412551A0; FR2548309B1; GB2142697B; IT1180783B; FR2548309A1; GB8415946D0

Abstract

A clamping device, such as a brake of the like, has friction means 12 and a compensator for the wear of these friction means; the said compensator being designed to keep constant the forward and return stroke (C) of an element 20 clamping the friction means, and the clamping element being displaced during the forward movement under the action of a control means 21 via a unidirectional connection 22 and during the return under the action of a restoring means. The clamping element is attached, with a play (J) defining its constant stroke (C), to a stop 24 which is connected to a frame by means of a friction clutch which resists the restoring means and which yields to the control means. <IMAGE>

Description

SPECIFICATION Clamping device The present invention relates to a clamping device, such as a brake or the like, which has friction means and a compensator for the wear of these friction means, the said com pensator being designed to keep constant the forward and return stroke of an element clamping the friction means, the clamping ele.ment being displaced during the forward movement under the action of a control means via a unidirectional connection and during-the return under the action of a restor ing means.

In general terms, clamping devices, such as brakes or the like, equipped with such a wear compensator have a complex and sensitive construction.

The subject of the present invention is a clamping device, such as a brake or the like, of the type mentioned above, the construction of which is simple and convenient, together with an excellent mode of operation.

According to the invention, a clamping de vice, such- as a brake or the like, of the type mentioned above is- characterised in that the clamping element is attached, with a play defining its constant stroke, to a stop which is connected to a frame by means of a calibrated friction clutch, with resists the restoring means and which yields to the control means.

As a result of this arrangement, the con struction is particularly simple and robust and allows a constant stroke for the clamping element without any operating risk.

According to another characteristic, a core is mounted to rotate on the frame about a main axis, and the clamping element carries a journal which is engaged to rotate in the said core about an axis offset relative to the said main axis, the unidirectional- connection being a free-wheel coaxial with the said main axis and interposed between the core and the control means, the said stop interacting with the said core: According to another characteristic, the re storing means comprises friction means inter posed between the control means and the core advantageously consisting of leak proofing gaskets associated with the free wheel.

An embodiment of the invention is de scribed below with reference to the accom panying drawings in which: Figure 1 is a general diagrammatic view of a disk brake equipped with a wear compensa tor according to the invention, this brake being in a new condition and in the released position; Figure 2 is a view similar to Fig. 1, but in which the brake in a new condition is in the applied position; Figure 3 is a view similar to Fig. 2, but in which the brake in the applied position has worn friction means; Figure 4 is a view similar to Fig. 3, but in which the brake, the friction means of which are worn, is in the released position; Figure 5 is a view of part of Fig. 1 on a larger scale, in a section along the broken line V-V of Fig. 6; and Figure 6 is a corresponding view in a section along the broken line VI-VI of Fig. 5.

The embodiment illustrated in Figs. 1 to 6 relates, by way of non-limiting example, to a use of the invention in a disk brake for parking braking, especially for à motor vehicle. The control of the brake incorporates a wear-compensating device.

Fig. 1 shows at 10 the disk of the brake which has two opposite rotating tracks 11 A and 11 B designed to be frictionally engaged by friction means 1 2A and 12B consisting of brake pads. Each pad 12A, 1 2B comprises a lining made of friction material 1 3 integral with a support 14. Each pad 12A, 12B is laid against the corresponding friction track 11A, 11 B of the disk 10 by means of the surfact 1 5 of the lining 1 3 which is opposite the support 14. The force is transmitted by means of the support 14 to each pad 12A, 12B so as the clamp it against the disk 10.

The frame 1 6 of the brake consists of a floating stirrup which caps the disk 10 and in which the pads 12A and 12B are mounted.

The frame 1 6 has a reaction face 18, against which bears the support 14 of the pad 12B.

An element 20 clamping the friction means is provided and interacts with the pad 12A.

This clamping element 20 is mounted moveably on the frame 1 6 with a forward and return stroke C between a retracted release position (Figs. 1 and 4) and an advanced clamping position (Figs. 2 and 3) and vice versa, the clamping position being all the more advanced, the more the friction means 12A, 12B are worn.

The wear compensator is designed to keep the forward and return stroke C of the clamping element 20 constant, whatever the new or more or less worn condition of the friction means 12A, 12B. The clamping element 20 is displaced during the forward movement under the action of a control means 21 via unidirectional con(iection 22 and during the return under the action of a restoring means 23 (Fig. 6).

The clamping element 20 is attached, with a play J (Fig. 5) defining its constant stroke C, to a stop 24 (Fig. 6) which is connected to the frame 1 6 by means of a calibrated friction clutch 25, which resists the restoring means 23 and which yields to the control means 21.

More particularly, the calibrated friction clutch 25 is designed to oppose a predetermined resistance to any force tending to make it slide, the said clutch 25 being either fixed or sliding, depending on whether the force is less than or greater than this predetermined resistance, the said predetermined resistance being such as to predominate over the restoring means 23 and to be overcome by the control means 21.

A core 27 (Figs. 5 and 6) is mounted to rotate on the frame 1 6 about a main axis A.

The clamping element 20 carries a journal 28 which is engaged to rotate in the core 27 about an axis B offset relative to the main axis A.

The unidirectional connection 22 consists of a free-wheel which is coaxial with the main axis A and which is interposed between the core 27 and the control means consisting of a lever 21.

The stop 24 is provided by a column which is engaged with the play J in a hole 29 of the core 27 (Fig. 5 and 6).

The calibrated friction clutch 25 between the stop 24 and the frame 1 6 comprises a plate 30 mounted to rotate on the frame 1 6 about the main axis A of the core 27, and a friction washer 31 interposed between the plate 30 and the frame 1 6 and clamped by a calibrated elastic means, such as a Belleville washer 32.

In the example illustrated in Fig. 6, the restoring means comprise friction means 23 which are interposed between the control lever 21 and the core 27. These friction means advantageously comprise leak-proofing gaskets 23 associated with the free-wheel 27 so as to retain its iubricant.

In the position of rest (Fig. 1) the clamping element 20 is retracted to the right in Fig. 1 and is spaced from the pad 1 2A by the distance C, whilst the lever 21 is retracted and preferably bears against an abutment 33.

The brake is released.

For braking, the lever 21 is actuated downwards and, as a result of the free-wheel 22 which is then active, drives the core 27 integrally in rotation about the axis A. The hole 29 in the core moves freely around the stop 24, absorbing the play J corresponding to the distance C. The clamping element 20 is allowed to exert direct action on the pad 1 2A and, as a result of the reaction effect of the face 18, indirect action on the pad 1 2B, the effect of which is to grip the disk 10 between the pads 1 2A and 12B. The brake is applied (Fig. 2).

During the operation, the linings 1 3 of the pads 1 2A and 1 2B become worn. The clamping element 20 is allowed to advance to a greater extent towards the left in Fig. 2, as can be seen in Fig. 3 for applying the brake, this occuring all the more, the more the linings 1 3 are worn. At the same time, the core 27 is allowed to rotate to a greater extent, causing the column 24 to be driven by means of the hole 29, the clutch 25 being allowed to slip under the predominant effect of the control means 21. For the return towards the released position, the core 27 is allowed to rotate in the opposite direction as a result of the restoring means consisting of the friction leak-proofing gaskets 23. However, since the connection 25 predominates over these restoring means 23, the column 24 remains fixed and defines the return stroke of the core 27 by coming up against the bottom of the hole 29, thus giving the stroke C the constant value desired (Fig. 4).

The simple construction of the device according to the invention and its excellent mode of operation will be appreciated.

It will be noted that, in the example illustrated in Fig. 6, the lever 21 and the clamping element 20 are aligned, whilst the freewheel 22 is divided into two free-wheels arranged in a balanced way on either side of the clamping element.

The invention is not, of course, limited-to the embodiment described and illustrated, but embraces all alternative forms in the construction of its various elements and in its uses.

within the scope of the claims.

Claims

1. Clamping device. such as a brake. for clamping a body such as a rotating disc.

comprising: friction means operable to apply a clamping force to the body; a clamping element movable between a return position and a forward position in which it-urges the friction means into clamping engagement with the body; control means which acts via a unidirectional connection to displace the operating element during forward movement thereof; and restoring means which acts to displace the operating element during the return movement thereof; said device being characterised in that the clamping element is attached, with a play (J) defining its constant stroke (C), to a stop which is connected to a frame by means of a calibrated friction clutch, which resists the restoring means and which yields to the control means.

2. Device according to Claim 1, characterised in that the clamping element is mounted moveably with the forward and return stroke between a retracted release position and an advanced clamping position and vice versa, the clamping position being all the more advanced, the more the friction means are worn.

3. Device according to Claim 1 or Claim 2, characterised in that the friction clutch is designed to oppose a predetermined resistance to any force tending to make it slide, the said clutch being fixed or sliding, depending on whether the force is less than or greater than this predetermined resistance, said predetermined resistance being such as to predominate over the restoring means and to be overcome by the control means.

4. Device according to any preceding claim, characterised in that a core is mounted to rotate on the frame about a main axis (A), and the clamping element carries a journal which is engaged to rotate in the said core about an axis (B) offset relative to the said main axis (A), the unidirectional connection being a free-wheel which is coaxial with the said main axis and which is interposed between the core and the control means and a stop interacting, with said play (J), with said core.

5. Device according to Claim 4, characterised in that friction clutch between the stop and the frame comprises a plate mounted to rotate on the frame about the main axis (A) of the core, and a friction washer interposed between said plate and the frame and clamped by an elastic means.

6. Device according to Claim 4 or Claim 5, characterised in that the stop comprises a column engaged with the said play (J) in a hole in the core.

7. Device according to any one of Claims 4-6, characterised in that the restoring means comprises friction means interposed between the control means and the core.

8. Device according to Claim 7, characterised in that said friction means comprises leak-proofing gaskets associated with said free-wheel.

9. Clamping device substantially as described herein with reference to the accom panying- drawings.