GB2087996A

GB2087996A - Spot-type disc brake

Info

Publication number: GB2087996A
Application number: GB8132313A
Authority: GB
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1980-11-25
Filing date: 1981-10-27
Publication date: 1982-06-03
Also published as: GB2087996B; FR2494797A1; FR2494797B1; DE3044393A1

Abstract

A brake shoe (3) bears against a supporting component via a separate noise-reduction insulation element (13) which is composed of a metal carrier member (14) which has a sliding surface (18) and a damping layer (15) of a sound-attenuating material e.g. of elastomeric material on the side opposite the sliding surface. As shown, the sliding surface (18) is divided into two partial surfaces (16), (17). Sliding action may occur by sliding action of the inner layers of layer (15). A number of embodiments are described and illustrated e.g. there may be a further metallic layer. The element (13) may be attached to the supporting component e.g. by lugs on the further metallic layer or by gluing the damping member, or may be attached to the brake shoe. <IMAGE>

Description

SPECIFICATION Spot-type disc brake The present invention relates to a spot-type disc brake of the kind having supporting components which are stationary in a circumferential direction for the axially slidable seating of a brake shoe, which latter is arranged with clearance allowing motion between the stationary supporting components and which bears against the supporting components via a separate element, this element being made of layers of various materials in a composite method of construction and having a sliding surface for the displacement movement of the brake shoe.

In disc brakes of the kind referred to, the brake forces acting in a circumferential direction when braking will be transmitted from the brake shoes arranged on either side of the brake disc onto supporting components, such as the brake support member, brake housing, floating frame or floating caliper, which receive these brake forces. Inserted between the supporting components and the brake shoes are separate elements which serve among other functions to reduce the noises associated with the brake components.

A disc brake is known from US patent specification 3 357 523, wherein isolated elements between brake shoes and anchoring surfaces are intended to reduce brake noises. The brake shoes include anchoring surfaces for the brake forces acting in a circumferential direction which surfaces are designed as the circumferential surfaces of circular discs; a brake shoe is substantially composed of two circular discs which are arranged side by side, in parallel to the plane of the brake disc and connected by plane surfaces.The anchoring surfaces in the brake housing are formed by circle-shaped indentations which, apart from a clearance, correspond in diameter to the circular discs of the brake shoes; the support is effected by the circumferential circular surfaces abutting at each other Between the circumferential surfaces of the brake shoe and of the brake housing, a respective spring pin is arranged for each direction of rotation paraxially relative to the brake disc's axis, so that brake shoe and brake housing are resiliently clamped relative to each other by means of the spring pins; it is desired to limit low frequency vibrations of the brake shoe and to reduce grating noises thereby.It has to be regarded as a particular disadvantage of this known device that, though the vibrations assembly is detuned by the resiliency of the spring pin, the transmission of the vibrations from the brake shoes onto the brake housing, which takes place as a transmission of sound conducted through solids, will be by no means damped, since, upon actuation of the brake after the resilient compression of the spring pin by the brake force, the brake shoe and brake housing will not be in direct abutment with their circumferential circular surfaces in a sounddamped manner. In addition, the movement of the brake shoes, in particular the restoring movement, will be inhibited disadvantageously by the clamping of the brake shoe and brake housing.

A disc brake is described in German printed and published patent application DE-OS 29 01 904, wherein both brake shoes are supported in a circumferential direction on the brake housing via a joint intermediate disc which is located in the pad slot and made of a low-friction material. In one of the embodiments described, the intermediate disc is coated with polytetrafluoroethylene and angled in profile so that a resilient clamping and a restoring effect is ensured for each brake shoe.

The objects of this known arranged are: support of the brake shoes with low friction, restoring effect and protection against rattling noises. When the brake is applied, after having overcome the spring effect due to the angled-off profile, the brake shoe will abut with its intermediate disc at the supporting surface at the brake housing.

However, when the intermediate disc is coated, there is very little damping capacity due to the thin layer thickness and due to the low amount of attenuation inherent in the material, so that it may be left out of account. It has to be considered as another disadvantage of the known device that, according to the object to be achieved "low friction support", the PTFE-layer is applied on the surface of the intermediate disc close to the brake shoe; in this point of application, the layer is subject to greater wear which results in a reduced life.

A disc brake with floating frame is described in German utility model 70 09 723, wherein an elastic compound moudling is arranged between the frame and the brake support member, which moulding is, among others, required to have vibration-damping effects. In the device described, however, the brake shoe bears directly against the brake support member in an undamped way.

In the designs referred to above, undamped sound is conducted through solids directly from the brake shoes onto further brake components, and in particular onto the brake support member.

Thus, the sound vibrations are transmitted onto large-surface components and cause unpleasant loud noises, as for instance brake squeak, when the object is actuated.

It is, therefore, an object of the present invention to prevent in a disc brake the sounds conducted through the brake shoes from being transmitted undamped onto other brake components as, for instance, the brake support member, the brake housing or the brake caliper.

Consequently, in a wider sense, it is an object of the present invention to provide a disc brake causing little noise.

According to the invention in its broadest aspect, a spot-type disc brake of the kind referred to is characterised in that the element is composed of a metal carrier member, which includes the sliding surface, and of a layer of a sound-attenuating material, which is applied on the part of the carrier member remote from the sliding surface.

By arranging for a separate element between the brake shoe and supporting component in the disc brake according to the invention, the assembly inhibiting sound vibration produced by friction processes, which assembly has so far been assumed to consist of, for instance, the main components brake support member or brake housing with brake shoes, will be detuned to reduce noises. A decisive reduction of noises with regard to sound conducted through solids will be accomplished by the damping layer which prevents the transmission of undamped vibrations from the brake shoe onto larger-surface components and thereby almost completely suppresses the development of noises near their source. This is a more effective and simpler way in contrast to, for example, the reduction of sound radiation in a floating frame by means of applied damping coatings.By arranging for the insulating element separately, it may be manufactured independently in a very favourable manner by suitably forming it and by using appropriate materials.

The application of another layer of metal on the rear side of the layer of sound-attenuating material which is arranged with its front face at the carrier member enables a straightforward and low-cost attachment and a stable design of the insulating element. particularly with respect to a subdivided carrier member.

When the sound-attenuating material is an elastomer with a high coefficient of inner vibration absorption, there is a choice among a variety of suitable substances which also afford ease of processing.

Moreover, the sound damped support may be employed expediently in ali known spot-type disc brakes; the insulating element can be attached to the supporting components or alternatively to the brake shoes.

If both brake shoes are supported on one insulating elment, the restoring movement of the brake shoes will be assisted in a simple manner by the sliding surface being subdivided and by the elastomeric damping layer.

A safe and simple fastening method is the gluing of the damping layer to the supporting component; when a metallic layer is put on the rear side of the damping layer, lugs can be shaped from this metallic layer which secure the installation element by a resilient catching engagement Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a sectional view of the pad slot of a fixed-type caliper disc brake having an sounddamped support for the brake shoes, according to the present invention.

Fig. 2 is a perspective view of a brake support member of a first-type caliper disc brake according to the present invention, Fig. 3 is a fist-type caliper disc brake having a support for the brake shoe according to the present invention.

Fig. 4 is a part of a brake shoe support according to the present invention.

Fig. 1 is a sectional view taken along the brake housing 1 of a fixed-type caliper disc brake. In the pad slot 2, the brake shoes 3,4 which are arranged on either side of the brake disc (not shown) are retained in a radial direction by the brake-shoes' setpins 5, 5' secured to the brake housing 1, only one of which is shown, in that these setpins extend through the retaining openings 6, 7 in the pad carrier plates 8, 9 and in the intermediate layers 10, 1 liThe retaining openings 6, 7 are in the form of oblong holes thus enabling a limited movement of the brake shoes 3,4 in a circumferential direction.The support of the brake force generated during a braking operation in a circumferential direction is effected by the brake shoe 3, 4 abutting at the narrow side 12 of the pad slot 2, this narrow side acting as a supporting component, by the intermediary of the insulating element 1 3. The insulating element 1 3 is composed of a carrier member 14 made of metal and a damping layer 1 5 fixed to it which is made of a material having a high inner damping quality with respect to sound vibrations. The layer 1 5 may be made, for instance, of an elastomeric material. Along the radial extension of the slot, the sliding surface 1 8 of the carrier member 14 is subdivided into two partial surfaces 1 6, 1 7 of approximately the same size.When the brake is applied, the brake force will be transmitted onto these partial surfaces 16, 1 7 by the narrow sides 20, 21 of the pad carrier plates 8, 9 with the brake force being finally supported at the brake housing 1 by the intermediary of the damping layer 1 5.

The damping layer 1 5 reduces the sound conducted through solids to be transmitted from the brake shoe 3, 4 which abuts at the brake housing 1 via the insulating element 13, onto the brake housing 1 and thus onto brake components of larger surfaces. By subdividing the sliding surface 18 of the carrier member 14 into two parallel surfaces 1 6, 17 and by virtue of the elastomeric material of the damping layer 1 5, the parts of the carrier member 14 having the partial surfaces 16, 1 7 will be able in the event of the brake shoes 3, 4 abutting at them to follow the latter's axial movement in the direction of the brake disc during a brake actuation provided that these movements are short with respect to the deformability of the elastomer. The decrease of the elastic deformation of the damping layer 1 5 which deformation took place in an axial direction assists the resetting of the brake shoes 3, 4. Thus, when the brake shoes 3, 4 are axially displaced to a small extent during a brake application, the narrow sides 20, 21 of the brake-pad carrier plates 8, 9 will not slide on the partial surfaces 1 6, 1 7. Instead, there will occur some kind of a sliding action of the inner layers of the damping layer 1 5 relative to one another.

Fig. 2 shows sound-damped supports of both brake shoes on a brake support member 22 of a fist-type caliper disc brake. The brake support member 22 includes two arms 23, 23' which are spaced from each other in a circumferential direction, only one of them being shown in the drawing, and which extend parallel to the axis of rotation of the brake disc (not shown); the arms 23, 23' are interconnected via a web 24 by which the brake support member 22 can be fastened to the vehicle. An insulating element 40 is assigned to each one of the arms 23, 23'. After assembly, the brake disc will be located in the recess 25.

Viewed from this recess 25, portions of the arm 23 and of the insulating element 40 will be situated on both sides of the brake disc and form supports 26, 27 for one of the hammer-shaped ends of a brake shoe (not shown), respectively.

The supports 26, 27 are of prismatic design and arranged axially aligned in series. The partial surface 28, 29 of the insulating element 40 serves to support the brake force for the pushed trailing end of the assigned brake shoe, while the partial surface 30, 31 serves to support the pulled leading end of the assigned brake shoe. In this way, the brake forces will be distributed more evenly onto both arms 23,23' of the brake support member 22. The surfaces 32, 33 and 34, 35 serve for radially mounting the brake shoes. The partial surfaces 28, 30 and 29, 31 and the surfaces 32,34 and 33,35 are parts of the sliding surface 19 of the carrier member 36, which is subdivided into two pieces, and are located at correspondingly-formed surfaces of the brake support member 22, with an undivided damping layer 37 and another metallic layer 51 being interposed.The attachment of the insulating element 40 is, for instance, carried out by two lugs 38, 39 of the metallic layer 51 engaging in correspondingly shaped recesses of the brake support member 22. The damping layer 37 reduces the transmission of the sounds conducted through solids from the brake shoe to the brake support member 22 and onto other brake components.

Since, also in this embodiment, the slidirig surface of the carrier member 36 is subdivided into two partial surfaces 28, 30 and 29, 31 and the damping layer 37 is made of an elastomer, a restoring effect will also be achieved in this case.

Fig. 3 shows another design of the support of the brake shoe of a first-type caliper disc brake.

The brake shoe 41 bears against the brake support member 43 in a sound-absorbing manner by the intermediary of the insulating elements 42,42'.

The attachment of the insulating elements 42,42' to the brake support member 43 is effected by gluing the damping layer 44, 44' to the brake support member 43.

Fig. 4 shows an insulating element 45 which is secured to a brake shoe 50 and which is composed of a carrier member 46 with a sliding surface 47, a damping layer 48 and another metallic layer 49, the latter being intended for attachment to the brake shoe 50. Since in this arrangement one insulating element 45 is provided for each brake shoe end, the resetting of the brake shoes will be likewise assisted, as has been described with regard to the preceding embodiments.

In a further embodiment, not shown in the drawing, the insulating element is arranged loosely in a circumferential direction between the brake shoe and supporting component.

Claims

1. A spot-type disc brake of the kind having supporting components which are stationary in a circumferential direction for the axially slidable seating of a brake shoe, which latter is arranged with clearance allowing motion between the stationary supporting components and which bears against the supporting components via a separate element, this element being made of layers of various materials in a composite method of construction and having a sliding surface for the displacement movement of the brake shoe, characterised in that the element (13, 40, 42, 45) is composed of a metal carrier member (14, 36, 46) which includes the sliding surface (18, 19, 47) and of a layer (15, 37,44, 48) of a soundattenuating material, which is applied on the part of the carrier member (14, 36, 46) remote from the sliding surface (18, 19,47).

2. A disc brake as claimed in claim 1, characterised in that another layer (49, 51) made of metal is applied on the rear side of the layer (37 48) of sound-attenuating material which is arranged with its front face at the carrier member (36, 46).

3. A disc brake as claimed in any one of the preceding claims, characterised in that the soundattenuating material is an elastomer with a high coefficient of inner vibration absorption.

4. A disc brake as claimed in any one of the preceding claims, characterised in that the supporting component is the brake housing (1) of a fixed-type caliper disc brake or the brake support member (22,43) or the floating caliper of a floating-caliper disc brake.

5. A disc brake as claimed in any one of the preceding claims, characterised in that the element (13, 40, 42) abuts with its side remote from the sliding surface (1 8, 19) at the supporting components (1, 22, 43) and is fastened thereto.

6. A disc brake as claimed in claim 5, characterised in that an element (13,40,42) supports the two associated ends of both brake shoes, in that the carrier member (14,36) consists of two parts, in that one of these parts is assigned to one brake shoe (3, 4, 41), respectively, and in that the parts of the carrier member (14, 36) which have the sliding surfaces (16, 17, 28, 29, 30,31) are axially siidable within limits.

7. A disc brake as claimed in any one of the preceding claims, characterised in that each element (45) abuts with its side remote from the sliding surface (47) at the two ends of the brake shoe (50) and is fastened to the latter.

8. A disc brake as claimed in any one of the preceding claims, characterised in that the attachment is carried out by resilient engaging means or by gluing.

9. A spot-type disc brake substantially as described with reference to the accompanying drawings.