GB2120330A

GB2120330A - Floating-caliper disc brake

Info

Publication number: GB2120330A
Application number: GB08307316A
Authority: GB
Inventors: Herbert Schmidt
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1982-05-19
Filing date: 1983-03-16
Publication date: 1983-11-30
Also published as: FR2527286B1; IT8321172A1; GB8307316D0; FR2527286A1; DE3219030A1; IT8321172A0; GB2120330B; IT1161846B; DE3219030C2

Abstract

The brake has two axial guide bolts (12) which are fastened to brake support member (11) and on which the floating caliper (15) is axially slidably guided by means of guide bores (13). At least one of the bolts (12) is detachable to enable the caliper (15) to swing radially outwardly about the other bolt (12) for brake shoe replacement. At the fastening point (16) of at least one bolt (12) where the threaded end (12') enters threaded bore (37) of support member (11) there is provided between the caliper (15) and the bolt an elastic pleated bellows (17) which seals the gap (18) between the guide bore (13) and the axial guide bolt (12). The pleated bellows (17) is arranged at caliper (15) in a torsionally-secured manner, while it is arranged rotatably at the axial guide bolt (12) close to the fastening point (16), so that the bellows (17) rotates with the caliper (15) as it is swung outwardly. A number of embodiments of bellows (17) are illustrated and described - those of Figures 3, 4, 5 utilize radially inner and outer guard plates for engagement one with the caliper and the other with the bolt. <IMAGE>

Description

SPECIFICATION Floating-caliper disc brake This invention relates to a floating-caliper disc brake, of the kind including a first-type caliper with two axial guide bolts which are fastened to the brake support member and on which the floating caliper is axially slidably guided by means of guide bores, at least one of the guide bolts being detachable in order to enable the floating caliper to swing radially outwardly about the other axial guide bolt for the purpose of brake shoe replacement, the end face of the axial guide bolts that is remote from the fastening point in the brake support member being covered by a protective cap secured to the floating caliper.

In floating-caliper disc brakes which are in particular equipped with a first-type caliper or a caliper bridge, axial guide bolts of various design are frequently made use of in order to guide axially the floating caliper at the brake support member in a reliable manner. For the compensation of tolerances and for the damping of vibrations, an elastic sleeve is often arranged around one of the axial bolts.

It is already known to employ pleated bellows to seal the slide surfaces between the axial guide bolt and the guide bore encompassing it (German printed and published patent application 25 38 352, 26 19 984, 27 30 338). Moreover, attempts have been made (German printed and published patent application 26 37 068) to arrange for sealing by sleeves sliding telescopically into each other.

All known solutions exhibit the disadvantage that either the sealing is insufficient or that there is danger of torsion of the pleated bellows when swinging the floating caliper outwardly after removal of one of the axial guide bolts. Besides, the known sealing sleeves are exposed to the outside, that is to say, they are unprotected, as a result whereof they will be easily damaged or contaminated by stones, dirt or mud, in particular in use of the brake in vehicles off the road.

It is thus an object of the present invention to provide a floating-caliper disc brake of the kind initially referred to, which will not be subject to torsion when the caliper is swung about the bolt, while it affords proper sealing of the space between the guide bore and the axial guide bolt.

According to the invention in its broadest aspect, a floating-caliper disc brake of the kind referred to is characterized in that an elastic pleated bellows is arranged at the fastening point of at least one axial guide bolt between the floating caliper and the axial guide bolt, which pleated bellows seals the gap between the guide bore and the axial guide bolt, which is fitted to the floating caliper in a torsionally-secured manner and to the axial guide bolt near the fastening point in a rotatable manner.

Consequently, the invention arranges for the pleated bellows to be rotatably arranged with respect to the axial guide bolt so that there is no danger of torsion when the floating caliper is swung about this bolt.

A sliding movement of the pleated bellows on the axial bolt which causes particularly little friction will be obtained, if a metal ring is fastened, in particular buttoned, to the inside of the pleated bellows' end that is fitted to the axial guide bolt, the metal ring being seated rotatably on the axial guide bolt. In this construction, there is friction of metal on metal, whereby practically no torsion forces will be transmitted onto the pleated bellows. The metal ring is preferably made of steel.

It is furthermore expedient if the pleated bellows forms on the side of the metal ring close to the fastening point an annular sealing lip which latter is in sealing engagement with the axial guide bolt. In this embodiment, the annular sealing lip does not have any retaining function for the pleated bellows but will abut on the axial guide bolt with very low pressure so that sealing is just ensured. Thus, according to the invention, the functions of retaining and of sealing are taken care of by two different elements.

To safeguard a proper axial fixation of the metal ring, the ring is arranged to abut with its end remote from the fastening point on an annular step of the axial guide bolt.

With a view to sealing against outside influences also the fastening point and the thread, into which latter the axial guide bolt is screwed, according to a particularly preferred embodiment, another circular sealing lip is provided frontally on the end of the pleated bellows that is fitted to the axial guide bolt, which sealing lip is in sealing engagement with an opposite surface of the brake support member. As the pleated bellows is of elastic material, the frontal sealing lip urges at the same time the metal ring against the annular step of the axial guide bolt.

It is furthermore suitable to have a cylindrical attachment encompass the axial guide bolt with a radial distance at the end of the pleated bellows that is secured to the floating caliper, which attachment is pressed into a complementary cylindrical recess of the floating caliper. To this end, the cylindrical attachment comprises a circumferential flange which abuts axially on the edge of the recess. In particular, the design.is such that there is provided a cylindrical metal insert if necessary, with a radially outwardly bent-off flange - in the cylindrical attachment and, if necessary, also in the circumferential flange. This ensures a safe and also seal-tight fixation of the other end of the pleated bellows at the floating caliper.

The pleated bellows may contain several radially extending peripheral pleats. In this case, the cylindrical attachment is in radial alignment with the pleats, while the portion carrying the metal ring and the annular sealing lips extends axially to the fastening point beyond the pleats.

It is another object of the present invention to protect the pleated bellows against stones, mud and dirt in particular when used in vehicles off the road. This object will be achieved in'a floating caliper disc brake bf the type referred to hereinabove in that the pleated bellows extends radially spaced in an axial direction between two cylindrical guard plates which overlap each other axially, with the ends of the guard plates that are not fastened to the pleated bellows being coupled to the axial guide bolt or the floating caliper, respectively, in a sealed manner.

In this arrangement, the radially outer guard plate serves as a protection for the elastic and rather susceptible pleated bellows.

According to a first practical embodiment, the guard plate connected to the axial guide bolt is arranged radially inwardly of the pleated bellows, while the other one is arranged radially outwardly thereof. Though dirt is still permitted to enter into the space between the inner guard plate and the pleated bellows in this case, the pleated bellows will get rid of the dirt by itself by rolling it off during operation.

In another embodiment, the radially inner guard plate is connected in the area of the fastening point to an elastic sealing ring which is seated on the axial guide bolt in a sealed and preferably rotatable manner. To this effect, it is provided in particular that the radially inner guard plate comprises at the point it is connected to the sealing ring a flange disposed in a radial plane, which flange, analogous to the metal ring mentioned, is arranged rotatably on the axial guide bolt and, if necessary, abuts on the annular step.

This ensures likewise a torsion-free tilting of the caliper about the axial guide bolt.

It is, however, also possible for the guard plate which is connected to the axial guide bolt to be placed radially outwardly of the pleated bellows, while the other one lies radially inwardly thereof.

This embodiment, too, enables the radially outer guard plate to be connected in the area of the fastening point to an elastic sealing ring which is seated on the axial guide bolt in a sealed and preferably rotatable manner. Furthermore, it will be expedient also in this embodiment, if the radially outer guard plate comprises at the point it is connected to the sealing ring a flange which is disposed in a radial plane and which is arranged, in an analogous way to the metal ring mentioned, rotatably on the axial guide bolt and abuts on the annular step, if necessary.

If it is, for instance, desired to have no rotational engagement of the pleated bellows with that axial guide bolt that is screwed out during pad replacement, that is to say, about which guide bolt the caliper does not have to be swung, according to another embodiment, the flange is, without an elastic sealing ring, clamped in directly between the axial guide bolt and the brake support member. In this arrangement, the guarding function for the pleated bellows will be fully maintained.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a partial cross-sectional radial view from the outside of a fist-type caliper brake according to one embodiment, Fig. 2 shows the section II in Fig. 1 on an enlarged scale, Fig. 3 is a view similar to Fig. 2 of another embodiment, Fig. 4 is a view analogous to Fig. 2 of a variation of the embodiment of Fig. 4, and Fig. 5 is a view analogous to Fig. 5 of a variation of the embodiment of Fig. 4.

According to Figs. 1 and 2, axial guide bolts 12 are screwed from the wheel inner side into two circumferentially spaced retaining arms of the brake support member 11. Interposed between the retaining arms of the brake support member 11 is a first-type caliper 1 5 which contains axial guide bores 13 in attachments 15' that are arranged beside the hydraulic cylinder 34. In the left-hand guide bore 13, when viewing Fig. 1, there are arranged one or two metal guide bushings 35. Between the guide bushings 35 and the guide bore 13, the right-hand guide bore 1 3 accommodates an elastic sleeve 36 which latter serves to absorb vibrations and to compensate for manufacturing tolerances.

The fist-type caliper 1 5 is axially slid on to the guide bolts 12 by means of the guide bushings 35.

Thus, the caliper is able to perform movements relative to the axial guide bolts 12 during braking.

With increasing wear of the outer brake pad, the guide bushings 35 are constantly moving inwards on the axial guide bolts 12.

To prevent the ingress of dirt into the space between the axial bolts 12 and the guide bores 13, protective caps 14 are put on the attachments 1 5' from the wheel inner side.

To prevent the penetration of dirt or water into the space between the guide bores 1 3 and the axial guide bolts 1 2 also from the axially opposite side, pleated bellows 1 7 are provided at the fastening point 16, where the threaded tapered end 12' of the axial guide bolts 12 enter into the assigned threaded bore 37 of the brake support member 11, which pleated bellows are coupled, on the one hand, to the attachment 1 5' of the fisttype caliper 1 5 and, on the other hand, to the axial bolt 12 in the manner shown in detail in Fig. 2.

According to Fig. 2, a steel ring 1 9 is buttoned in the end of the pleated bellows 17 that is close to the fastening point 1 6. For this purpose, the respective end of the pleated bellows 1 7 contains an inner annular groove 38 which is confined radially outwardly such that the steel ring 1 9 is permitted to stand out radially inwardly in the manner shown in Fig. 2. The steel ring 19 is arranged rotatably on the end of the axial guide bolt 1 2 which end is somewhat tapered via an annular step 21. In the direction of the fastening point 16, there is disposed beside the steel ring 1 9 an annular sealing lip 20 which is radially from the outside in sealing engagement with the outer periphery of the axial bolt 1 2. Additionally, the end of the plated bellows 1 7 that is close to the fastening point 1 6 includes an annular frontal sealing lip 22 which co-operates with a surface 23 of the brake support member 11 in the manner illustrated. In this way, it is not only the gap 1 8 between the guide bore 13 and the axial guide bolt 12 which is reliably sealed to the outside, but also the annular chamber 39 which is adjacent to the gap between the axial guide bolt and the threaded bore 37. Thus, the protective cap 14 (Fig. 1) as well as the sealing lips 20, 22 ensure that all delicate parts around the axial guide bolt 1 2 are sealed completely relative to the outside.

Starting from the end that carries the sealing lips 20, 22, the pleated bellows 1 7 extends first via a somewhat conically enlarged, inwardly extending portion 40 away from the brake support member 11 and then passes on radially outwardly into a cylindrical attachment 24 via four pleats 30 which extend alternately in opposite directions, the cylindrical attachment being pressed into a complementary shaped cylindrical recess 25 in the attachment 1 5' of the floating caliper 1 5. To ensure a well-defined depth of indentation, the cylindrical attachment 24 comprises a circumferential flange 26 which moves into abutment on the edge 27 of the recess 25.

To provide the cylindrical attachment 24 and the flange 26 with sufficient rigidity, the cylindrical attachment 24 contains a substantially cylindrical metal insert 28 which latter passes on into a radially outwardly bent-off flange 29 in the area of the circumferential flange 26.

When braking and with increasing pad wear, the attachment 1 5' of the floating caliper moves in relation to the axial guide bolt 1 2 steadily further in the direction of the arrow F in Fig. 2, while the cylindrical attachment 24 and the portion 40 of the pleated bellows 1 7 are likewise displaced axially relative to one another. The pleats 30 roll off in an axial direction for length compensation, while the sealing engagement of the sealing lips 20, 22 is fully maintained.

In the event of brake shoe replacement, the right-hand axial guide bolt 12, as seen in Fig. 1, will be screwed out after removal of the protective cap 14. Subsequently, the first-type caliper 1 5 will be swung radially outwardly about the left axial bolt 1 2. In doing so, the pleated bellows 1 7 which is unrotatably secured to the floating caliper 1 5 or to its attachment 15', respectively, joins in the rotational movement because the steel ring 1 9 is able to slide on the axial guide bolt 12 in a largely frictionless way. Since the sealing lips 20, 22 perform a mere sealing function, they are able to abut on their mating surfaces so lightly that they do not inhibit the co-rotation of the pleated bellows 17.

In the following descriptions of further embodiments, parts which correspond to parts in Figs. 1 and 2 have been assigned like reference numerals.

According to Fig. 3, the pleated bellows 1 7 is of substantially cylindrical shape. It extends in essence in an axial direction. Via a flange-like bent-off portion 17', the pleated bellows 17 is prevulcanized to a radially outer cylindrical guard plate 32 which latter overlaps the pleated bellows 1 7 to a large extent. The other end of the guard plate 32 is fastened to the recess 25 of the attachment 15' of the fist-type caliper 15 in a sealed and torsionally-secured manner.

The end of the pleated bellows 1 7 that is remote from the fastening point 1 6 is prevulcanized via a pleat 30 to a further, radially inner guard plate 31 which latter likewise overlaps axially the pleated bellows 1 7 and the outer guard plate 32 to a large extent. Radially, however, there are distinct distances between the guard plates 31,32 and the pleated bellows 1 7.

The end of the radially inner guard plate 31 that is close to the fastening point 1 6 is bent off to form a flange 40' which latter is disposed in a radial plane and, similar to the steel ring 1 9 according to Fig. 2, is arranged rotatably on the axial bolt 12. As viewed in an axial direction, the flange 40' abuts on the annular step 21. On the side remote from the annular step 21, there is prevulcanized to the flange 40' an elastic sealing ring 33 which, by abutting on the surface 23 of the brake support member 11, provides for the necessary sealing between the guide bore 13 and the axial guide bolt 12.

Also in this embodiment, the fist-type caliper 1 5 is able to tilt about the axial bolt 12 without difficulty, and the pleated bellows 1 7 including the guard plates 31, 32 arranged thereat are permitted to join in this rotational movement because both the flange 40 and the elastic sealing ring 33 are able to slide on the axial bolt 12.

Admittedly, dirt is allowed to ingress into the space 41 between the pleated bellows 1 7 and the radially inner guard plate 31, however, the pleated bellows 1 7 will roil over the dirt upon application of the brake. Thus, its function will not be impaired thereby.

The radially outer guard plate 32 serves to protect the pleated bellows 1 7 reliably against stones and other mechanical influences.

In the embodiment according to Fig. 4, the radially outer guard plate 31 is, via a sealing ring 33, supported rotatably in a circumferential annular groove 42 of the axial guide bolt 12. The pleated bellows 1 7 prevulcanized to the guard plate 31 extends up to the radially inner guard plate 32 which latter is via an angularly bent portion 43 seal-tightly secured to the recess 25 of the attachment 1 5' of the fist-type caliper 1 5.

Also in this case, the pleated bellows 1 7 is protected against mechanical outside influences.

It is able to follow the rotational movements of the fist-type caliper 15, since the sealing ring 33 is supported rotatably in the circumferential groove 42 of the axial guide bolt 12.

The embodiment according to Fig. 5 differs from that of Fig. 4 only in that the radially outer guard plate 31 passes on radially inwardly into a flange 40 in the area of the fastening point 16, which flange however, is not secured rotatably to the axial bolt 12 as is the case in the embodiment according to Fig. 3. Instead, the flange 40 is clamped in between the brake support member 11 and a small radial projection 44 of the axial bolt 12 in the embodiment of Fig. 5.

A like embodiment of the pleated bellows 17 is appropriate for instance for fitting to the righthand axial guide bolt 12 in Fig. 1 , wherein there is no relative tilting movement between the attachment 15' and the axial bolt 12.

It has to be stated still in respect of the embodiment of Fig. 2 that the steel ring 1 9 has to be seated relatively tightly in the pleated bellows 1 7 to the end that it provides for a proper guidance for the axial guide bolt which, under certain circumstances, will be screwed out and in, respectively, during pad replacement.

The chamber 19 according to Fig. 2 can also be made use of as a grease-receiving chamber

Claims

1. A floating-caliper disc brake of the kind including a fist-type caliper, with two axial guide bolts which are fastened to the brake support member and on which the floating caliper is axially slidably guided by means of guide bores, at least one of the guide bolts being detachable in order to enable the floating caliper to swing radially outwardly about the other axial guide bolt for the purpose of brake shoe replacement, the end face of the axial guide bolts that is remote from the fastening point in the brake support member being covered by a protective cap secured to the floating caliper, characterized in that there is provided at the fastening point (16) of at least one axial guide bolt (12) between the floating caliper (15) and the axial guide bolt (12) an elastic pleated bellows (17) which latter seals the gap (18) between the guide bore (13) and the axial guide bolt (12), which is arranged at the floating caliper (15) in a torsionally-secured manner, while it is arranged rotatably at the axial guide bolt (12) close to the fastening point.

2. A floating-caliper disc brake as claimed in claim 1, characterized in that a metal ring (19) is fastened, in particular buttoned in, radially inwardly at the end of the pleated bellows (17) that is secured to the axial guide bolt (12), the metal ring being seated on the axial guide bolt (12) in rotational sliding engagement.

3. A floating-caliper disc brake as claimed in claim 2, characterized in that, on the side of the metal ring (19) close to the fastening point (16), the pleated bellows (17) forms an annular sealing lip which is in sealing engagement with the axial guide bolt (12).

4. A floating-caliper disc brake as claimed in claim 2 or 3, characterized in that the metal ring (19) abuts with one end remote from the fastening point (16) on an annular step (21) of the axial guide bolt (12).

5. A floating-caliper disc brake as claimed in any one of claims 2 to 4, characterized in that, at the end of the pleated bellows (1 7) which is attached to the axial guide bolt (12), there is provided a frontal circular sealing lip (22) which latter is in sealing engagement with an axially opposite surface (23) of the brake support member (11).

6. A floating-caliper disc brake as claimed in any one of the preceding claims, characterized in that, at the end of the pleated bellows (17) which is attached to the floating caliper (15), there is provided a cylindrical attachment (24) which encompasses the axial guide bolt (12) spaced radially therefrom and which is urged into a complementary cylindrical recess (25) of the floating caliper (15).

7. A floating-caliper disc brake as claimed in claim 6, characterized in that the cylindrical attachment (24) comprises a circumferential flange (26) which latter abuts axially on the edge (27) of the recess (25).

8. A floating-caliper disc brake as claimed in claim 6 or 7, characterized in that a cylindrical metal insert (28) having a radially outwardly bentoff flange (29) is provided in the cylindrical attachment (24) and also in the circumferential flange.

9. A floating-caliper disc brake as claimed in any one of the preceding claims, characterized in that the pleated bellows (17) has several radially aligned peripheral pleats (30).

10. A floating-caliper disc brake as claimed in any one of claims 1 to 8, characterized in that the pleated bellows (17) extends with radial distance axially between two cylindrical guard plates (31, 32) which latter overlap each other axially, with the ends of the guard plates (31, 32) that are not secured to the pleated bellows (17) being sealingly connected to the axial guide bolt (12) or the floating caliper (15), respectively.

11. A floating-caliper disc brake as claimed in claim 10, characterized in that the guard plate (31) connected to the axial guide bolt (12) is arranged radially inwardly of the pleated bellows (17) while the other one lies radially outwardly thereof.

12. A floating-caliper disc brake as claimed in claim 11, characterized in that the radially inner guard plate (31) is in the area of the fastening point (16) connected to an elastic sealing ring (33) which latter is seated on the axial guide bolt (12) in a sealed and preferably rotatable manner.

13. A floating-caliper disc brake as claimed in claim 12, characterized in that the radially inner guard plate-(31) comprises at the point it is connected to the sealing ring (33) a flange (40) which latter is disposed in a radial plane, which is arranged rotatably on the axial guide bolt (12), analogous to the metal ring (19) and which abuts on the annular step (21).

14. A floating-caliper disc brake as claimed in claim 10, characterized in that the guard plate (31) connected to the axial guide bolt (12) is disposed radially outwardly of the pleated bellows (17), while the other guard plate (32) lies radially inwardly thereof.

15. A floating-caliper disc brake as claimed in claim 14, characterized in that the radially outer guard plate (31) is in the area of the fastening point (1 6) connected to an elastic sealing ring (33) which is seated on the axial guide bolt (12) in a sealed and preferably rotatable manner.

1 6. A floating-caliper disc brake as claimed in claim 15, characterized in that the radially outer guard plate (31) comprises at the point it is connected to the sealing ring (33) and flange (40') which latter is disposed in a radial plane, which is arranged rotatably on the axial guide bolt (12), analogous to the metal ring (19) and which abuts on the annular step (21).

17. A floating-caliper disc brake as claimed in claim 16, characterized in that the flange (40') is clamped, without an elastic sealing ring (33), directly between the axial guide bolt (12) and the brake support member (11).

1 8. A floating-caliper disc brake substantially as described with reference to the accompanying drawings.