GB2231928A

GB2231928A - Spot-type disc brake

Info

Publication number: GB2231928A
Application number: GB9008914A
Authority: GB
Inventors: Winfried Gerhardt
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1989-05-26
Filing date: 1990-04-20
Publication date: 1990-11-28
Anticipated expiration: 2010-04-20
Also published as: IT1240897B; GB9008914D0; GB2231928B; IT9020342A0; FR2647517A1; FR2647517B1; IT9020342A1

Abstract

A spot-type disc brake (1, 51) comprises a housing (2, 3, 55), two brake shoes (9, 10, 59, 60) and a friction lining warning device which indicates any wear of a friction lining (16, 17, 63, 64) at any one of the brake shoes (9, 10, 59, 60) and which includes electrical conductors (154, 155, 79, 80) associated with the brake shoes (9, 10, 59, 60) and with indicating apparatus. The spot-type disc brake (1, 51) is furnished with a holding device (33, 69) at which the electrical conductors (154, 155, 79, 80) are guided. The warning device of Fig. 1 includes transmitters (155, 159), whereas in the disc brake of Fig. 5 engagement of the conductors (79, 80) with a brake disc is indicative of friction lining wear. <IMAGE>

Description

brake.

1 SPOT-TYPE DISC BRAKE The present invention relates to a spot-type disc More specifically the invention relates to spot-type 5 disc brakes comprising a housing, two brake shoes and a friction lining warning device which indicates any wear of a friction lining at one of the brake shoes and which includes an electrical conductor leading f rom the brake shoe to indicating means.

A spot-type disc brake of the above construction in which the brake shoes are retained and guided by two retaining pins and in which the shoes are braced against the pins by spring means to prevent a rattling noise being produced by the shoes vibrating against the retaining pins.

An electrical conductor is positioned at each of the two brake shoes with the conductor ends projecting from the brake housing. These free conductor ends can hinder a mechanic during assembly and removal of the brake and they can f ray at the component part of the car body or at the brake during use of the automotive vehicle or can end up in the wheel rim or wheel dish and be severed. The present invention has as an object to secure an electrical conductor provided as aforesaid in spot- type disc brakes. 25 According to the present invention there is provided a spot-type disc brake comprising a housing, two brake shoes and a friction lining warning device which indicates any 2 wear of a friction lining at one of the brake shoes and which includes an electrical conductor leading f rom the brake shoe to indicating means characterised in that the spot-type disc brake is furnished with a holding device at which the electrical conductor is guided.

In this way, the electrical conductor is held so that it is not loosely and f reely suspended between the spot-type disc brake and the wheel dish. During use of the automotive vehicle especially the location between the wheel dish and the disc brake is subject to atmospheric exposure and to relative movement between the car body and the wheel. By means of the holding device provided by the invention a guide is created for the electrical conductor which leads it safely out of this highly stressed location.

Advantageously, the holding device is provided at the spring means which is positioned above the brake disc in a guide of the spot-type disc brake and which leads the electrical conductor out of the hazardous range of the rotating brake disc to the outer surface of the housing.

The spring means also braces the brake shoes against the retaining pins of the housing.

The spring means may be provided in the shape of a cruciform leaf spring with four webs with oppositely disposed pairs of webs being formed as single parts. Advantageously, a strap is arranged resiliently above one of the webs, so that the strap can be flexed away from the web and the electrical conductor slid between the flexed strap and the web of the spring.

In one embodiment, the strap may be f ixed to the spring means in the centre of the cruciform leaf spring by means of a rivet which also keeps together the two pairs of webs of the cruciform leaf spring.

In another embodiment of the invention, the strap is formed integrally with one of the webs by being stamped out of the web and directed parallel to the web.

Advantageously, the web which guides the electrical conductor is formed with a trough extending in the axial 1 3 direction of the brake disc and offering space to accommodate the electrical conductor between the strap and the web. The position of the electrical conductor at the spring means is fixed in this manner.

In yet another embodiment, the holding device comprises a projection with an opening through which the electrical conductor passes and by which it is guided, is provided at the brake housing. The projection can be formed as a cast projection being produced during fabrication of the housing casting.

The projection may be formed with two arms which surround the opening and whose ends define a slot of the opening. In an advantageous manner, the slot serves to insert the electrical conductor into the opening. The slot through which the electrical conductor can be inserted into the opening will be of advantage because the components associated with the electrical conductors, for example plugs and the brake shoe have considerably larger dimensions than the electrical conductor itself so that these components can only be introduced through a wide cast opening.

Advantageously, a protective sleeve of plastic material is inserted in the opening which guides, protects and/or insulates the electric conductor between the arms of the projection but without actually clamping the conductor.

The arms may be formed with a chamfer, so that the compressible sleeve can be slid between the projection arms in radial direction with respect to the electrical conductor.

The compressible sleeve may be formed with a chamfer, so that the sleeve can be inserted into the projection opening and clamped therein in the axial direction relative to the electrical conductor.

The protective sleeve may be provided with a slot, so that the protective sleeve can be compressed to enable it to be inserted between the arms.

By way of example different embodiments of the invention will now be described with reference to the 4 accompanying drawings. in which:

Figure 1 shows a top view of a f ixed-caliper disc brake including spring means for engagement with brake shoes; Figure 2 shows a side view of the fixed-caliper disc brake of Figure 1; Figure 3 shows a perspective representation of one form of spring means f or the retention of an electrical conductor in the brake according to Figures 1 and 2; Figure 4 shows a perspective representation of another form of spring means to that shown in Figure 3; Figure 5 shows the top view of a f loating-caliper disc brake having an electrical conductor guided by projection means; Figure 6 shows a perspective representation of a section of the f loating- caliper disc brake of Figure 5 having electrical conductors associated with a friction lining warning device guided by further projection means; Figure 7 shows an unmachined cast conductor holding projection; Figure 8 shows the machined cast conductor holding projection of Figure 7; Figure 9 shows the projection of Figure 8 accommodating a protective sleeve; Figure 10 shows a different form of conductor holding projection; Figure 11 shows a view of a further form protective sleeve; Figure 12 shows the top view of the protective sleeve of Figure 11; Figure 13 shows a side view of the protective sleeve inserted in the projection; and Figure 14 shows the view of the protective sleeve of Figure 12 inserted into the projection.

Figures 1 and 2 show a fixed-caliper spot-type disc brake 1 the housing 2,3 of which is divided asymmetrically into two housing parts 2,3. A bridge part 5 with two bridge I p sections 6,7 and an external housing web 4 of the housing part 2 define a guide opening 8. Within the guide opening 8,, two brake shoes 9,10 are retained by retaining pins 11,12. A spring 13 braces the brake shoes 9,10 against the pins 11,12. Each of the brake shoes 9,10 is provided with a carrier plate 14,15 and with a friction lining 16,17. The two housing parts 2,3 are secured together by screws 18,19,20 and 21. The external web 4 embodies actuating devices each comprising a piston 22 and a cylinder 23 which urge the lining of brake shoe 9 against a brake disc not illustrated in the drawing. The brake 1 as a whole will be secured to the steering knuckle of an automotive vehicle by a flange 24 of the housing part 3. Two actuating devices in an internal housing web 25 of the housing part 3 each comprise a piston which is moveable within a cylinder to urge the lining of the internal brake shoe 10 against the other side of the brake disc. The internal brake shoe 10 is supported at the flange portion 24 and the external brake shoe 9 is supported at the bridge sections 6,7. The spring 13 takes the form of a cruciform sheet steel leaf spring with four spring webs 26,27,28 and 29. Those.webs 26 and 27, 28 and 29 positioned opposite each other comprise onepart structures and form pairs of spring webs which are secured together by a rivet 30. The webs 28,29 extend under the retaining pins 11,12, and the webs 26,27 are supported on peripheral areas 31,32 of the brake shoe carrier plates 14f1S. The rivet 30 secures a strap 33 which is disposed parallel to - the unitary webs 28,29. An electric plug strip 151 which accommodates the electric plugs 152,153 of friction lining warning devices 154,155 is mounted on the housing part 3 by means of a screw 150. The friction lining warning devices 154..155 comprise in addition to the two plugs 152,153, electric conductors 156j157 and two transmitters 158,159. A looped part 160 of the electric conductor 156 passes beneath the strap 33 whereas the unlooped electric conductor 157 simply passes beneath the strap 33 as shown.

6 Figure 3 shows the spring 13 of Figures 1 and 2 with a leaf-shaped strap 33 the section 34 of which extends substantially parallel to the web 28. The web 28 presents parts 35,37 on which the strap section 34 is supported and between them a part 36 which has a trough-shaped configuration and which is positioned at a distance in radial direction from the strap section 34 extending substantially in one plane. A retaining part 38 of the web 28 give support to the spring 13 by engagement with the pin 11. The strap section 34 has an upturned end 39, so that between the strap end 39 and the part 37 an electric conductor 40 can be slid into the trough 36. Bends or steps 281,331 in the web 28 and the strap 33, respectively, act as anti-swivelling means so that the strap 33 will not swivel with respect to the web 28 whereby the electric conductor 40 becomes released from the trough 36 position as shown.

Figure 4 shows a different design version of the spring 13 but identical reference numerals are used for identical elements in Figure 3. A strap section 34 is stamped out of the web 28 and leaves an oblong opening 41 in the trough section 36. The trough section 3,6 is,, thus, formed by two narrow sections 42 and 43 which are positioned at a distance from each other amounting to the width of the strap section 34. By movement in the direction 44 of the electric conductor 40 of the warning device which is hereinafter referred to as a warning wire will slide under the bent-up strap end 39 and will cause the strap 34 to lift to allow the wire to move into the trough as shown.

Figure 5 shows a floating-caliper spot-type disc brake 51 with a brake carrier 52 which is fixedly mounted to a steering knuckle of an automotive vehicle. A brake housing 55 is saddle-shaped and is floatingly positioned at the brake carrier 52 through pin guides 53.54. The housing 55 comprises a first web part 56, a second web part 57 and a bridge section 58. The web part 57 accommodates an actuating device which comprises a piston guided within a cylinder and arranged to urge an internal brake shoe 59 z 7 directly and an external brake shoe 60 indirectly, through the external web part 56, against a brake disc (not shown). Each of the brake shoes 59, 60 comprises a carrier plate 61,62 and a friction lining 63,64. The brake shoes 59,60 are guided in grooves 65,66 of brake carrier arms 67,68. The housing 55 is supported at the carrier plate 62 of the external brake shoe 60. The web part 57 has a projection or flange 69 positioned so that the arms 70,71 thereof project radially outwardly in respect of the axis of the brake disc. The projection is arranged in a location 72 which is defined by a bottom area 73 of the cylinder of the actuating device and by ends 74,75 of ribs 76,77 of the web part 58. A guide opening 78 is arranged in the bridge 58 between the ribs 76,77. An electric conductor 79 is detachably secured in the friction lining 63 of the brake shoe 59. The conductor 79 comprises an electrically conductive wire 81 and an insulating sheath 83. An electric conductor 80 with an electrically conductive wire 82 and an insulating sheath 84 is positioned in the friction lining 64 of the external brake shoe 60. As the brake lining becomes worn away the friction lining will also be worn ' away and the electric wires 81,82 will be brought into electrical contact with the brake disc so that a current f low through the electrically conductive wires 81,82 and an indication of friction lining wear will be provided. The electric conductors 79,80 project from a peripheral surface 85,86 of the friction linings 63,64, i.e. from the brake shoes 59,60, and extend through the guide 78 and upwards to a surface 87 of the web part 57. The projection 69 is formed with an opening 88 which extends in the axial direction of the brake disc and is defined by the arms 70,71. Through the opening 88, the electric conductors 79,80 are guided so that they are contained and prevented from freely moving about.

Figure 6 shows a different configuration of projection 35 90 which is positioned at the floating-caliper disc brake 51. The projection 90 is formed with two arms 91,92 which define an opening 93. The ends 94,95 of the arms 91,92 are 8 spaced from each other by a slot 96. Through the slot 96 an electric conductor 97 of a friction lining warning device 98 may be inserted into the opening 93 as shown. The friction lining warning device 98 comprises the electric conductor 5 97, a plug 99 and a former 100. The former 100 is detachably fastened in the friction lining 59 or 60. An electrically conductive wire 101 with an insulating sheath 102 of the conductor 97 is looped around the former 100. Ends 103,104 of the wire 101 are terminated at the plug 99.

The plug 99 constitutes an indicating device at which the degree of wear of the friction lining 63,64 can be checked with the aid of electrical equipment. A protective sleeve 105 can be inserted in the opening 93 of the projection 90 in the direction 106 and secures the electric conductor 97 in the projection 90. If in the event of wear of the brake lining the electrically conductive wire 101 which is looped around the former 100 is severed by the brake disc, then a current flow will be interrupted and an electrical indication will be triggered in the device/plug 99.

Figure 7 simply shows the untooled cast projection 90 as a blank with the cast slot 96 and Figure ' 8 shows the tooled or machined projection 90 which has already been reamed out, so that the reamed opening 93 is formed.

Figure 9 shows the protective sleeve 105 of Figure 6 with three rings 107,108,109 which is inserted in the opening 93 of the projection 90. The rings 107 and 109 have a larger diameter than the ring 108, so that disc surfaces opposed to each other will abut against opposite sides of the arms 91,,92. The internal ring 108 abuts with its peripheral surface 112 in the opening 93 against the projection surface 113. A longitudinal slot 114 of the sleeve 105 extends across the rings 109 and 108 as far as the ring 107. The sleeve is thereby compressible in a radial direction and allows the sleeve to be inserted in the direction 106 into the opening 93 of the projection 90, a leading chamfer 115 of the ring 109 facilitating such insertion.

9 - Figures 10,11,12,13 and 14 show a projection 90 with an opening 93 into which a protective sleeve 119 may be inserted in a radial direction 116 which is also the radial direction with respect to the axis of the brake disc. Chamfers 117,118 at the ends 94,95 of the projection arms 91,92 facilitate the radial compression of the protective sleeve 119 and the insertion thereof into the opening 93. The protective sleeve 119 is furnished with three ringshaped sections 120,121 and 122 the external sections 120 and 122 having an enlarged diameter with respect to that of the section 121. In this way sleeve surfaces 123 and 124 which are opposed to each other will abut against the surfaces 125,126 of the arms 91 of the projection as shown in Figure 13. The sleeve 119 is formed with a radial slot 127, so that the rings 120,121, and 122 are compressible in the direction 128,129 toward the centre line 130 of the protective sleeve 119 so that the central ring 121 can be urged through the slot 96 in the direction 116 into the,opening.9 3. The chamfers 117,118 of the arms 91,92 facilitate the compression of the ring 121. On the side of the sleeve 119 opposite to the slot 127, a projection 131 is provided which extends over the total length of the protective sleeve 119 to prevent rotation of the sleeve within the bore 93 of the projection 90. The sleeve 119 is applied to the electric conductor 97 by inserting the electric conductor through the slot 127 into an axially extending opening 132 of the protective sleeve 119. The projection 1 ' 31 acts as an anti-rotating means for the sleeve within the bore 93 of the projection 90, so that the electric conductor 97 cannot fall out due to alignment of the slot 127 of the protective sleeve 119 with the slot 96 of the projection 90. The electrical conductor 97 is loosely held with radial play 133 within the opening 132 of the protective sleeve 119 so that the electric conductor 97 will remain undamaged when the protective sleeve is being inserted through the slot 96 in the direction 116 (Figure 10) and when the protective sleeve 119 is being compressed, and the conductor will advantageously be loosely guided in the axial direction in the event of wear of the brake lining. It will thereby be ensured that at the internal brake shoe in which the friction lining warning device is as a rule incorporated because of the heavier wear of the internal brake shoe lining in a floating-caliper spot-type disc brake, the electric conductor can move freely over a lining wear travel distance in the axial direction of the opening 93 and does not tear when the brake is being 10 operated.

11

Claims

CLAIMS:

1. A spot-type disc brake comprising a housing, two brake shoes and a friction lining warning device which indicates any wear of a friction lining at one of the brake shoes and which includes an electrical conductor leading from the brake shoe to indicating means characterised in that the spot-type disc brake is furnished with a holding device at which the electrical conductor is guided.

2. A spot-type disc brake as claimed in claim 1, characterised in that the holding device includes a strap which is associated with spring means bracing at least one of the brake shoes against the brake housing.

3. A spot-type disc brake as claimed in claim 2, characterised in that the spring means comprises a crucif orm- shaped leaf spring defining with four webs with oppositely disposed webs being single parts, the strap being resiliently positioned above one of the webs and serving to guide the electric conductor at the spring means.

4.-A spot-type disc brake as claimed in claim 2 or 3, characterised in that the strap is riveted to the spring means.

5. A spottype disc brake as claimed in claim 3 or 4 as dependent upon claim 3, characterised in that the strap and one of the webs of the spring means are formed as a single part.

6. A spot-type disc brake as claimed in any one of claims 2 to 5, characterised in that the web holding the electrical conductor is formed with a trough for receiving the conductor.

7. A spot-type disc brake as claimed in claim 1, characterised in that the holding device is provided on the brake housing in the form of a projection with an opening through which the electrical conductor passes and by which the conductor is guided.

8. A spot-type disc brake as claimed in claim 7, characterised in that the projection is formed with two arms which surround the opening and the ends of the arms defining 12 a slot extending into the opening.

9. A spot-type disc brake as claimed in claim 7 or claim 8, characterised in that between the arms and the electrical conductor a protective sleeve is positioned which surrounds the electrical conductor and holds the conductor between the arms.

10. A spot-type disc brake as claimed in claim 8 or claim 9, characterised in that the ends of the arms are formed with chamfers to facilitate entry of the electrical conductor into the opening of the projection.

11. A spot-type disc brake as claimed in claim 9 or claim 10 as dependent on claim 9, characterised in that the protective sleeve is formed with a chamfer.

12. A spot-type disc brake as claimed in claim 9 or in claim 11, characterised in that the protective sleeve is provided with a slot to facilitate compression thereof during insertion into the opening of the projection.

13. A spot-type disc brake substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

14. A spot-type disc brake substantially as hereinbefore described with reference to Figures 1,2 and 4 of the accompanying drawings.

15. A spot-type disc brake substantially as hereinbefore described with reference to Figures 5 to 14 of the accompanying drawings.

Published1990 a, Tk-,cPt-entOfficc.S,.ate House. 66 71Highl-lolborn. London WC1R4TP.Further copies maybe obtainedfrom The Patent Office. Sales Branch, St Ma7 Cray. Orpington, Kent BR5 3RD- Printed by Multiplex techniques ltd. St Mary Cray. Kent, Con- 1!87 W