GUIDE ASSEMBLY

Abstract

A guide assembly for a disc brake. The guide assembly includes a receiving portion of a brake carrier that receives a sleeve portion of a guide pin. The sleeve portion and receiving portion have corresponding non-circular cross-sectional profiles that restrict rotation of the sleeve portion relative to the brake carrier when the sleeve portion is received and aligned in the receiving portion. The present invention further relates to a disc brake that includes a brake carrier, a caliper, and at least one guide assembly and a method of manufacture.

Claims

1. A rotational fixing for a disc brake, the rotational fixing comprising: a guide pin having a guide sleeve; a brake carrier having a receiving portion that receives a portion of the guide sleeve; and a friction enhancer between the brake carrier and the guide sleeve, wherein the friction enhancer provides frictional engagement between the guide sleeve and the brake carrier such that the friction enhancer restricts rotation of the guide sleeve relative to the brake carrier when the portion of the guide sleeve is received in the receiving portion.

2. The rotational fixing of claim 1 wherein the guide sleeve includes a circumferential flange or rim arranged at a first end of the guide sleeve, and the friction enhancer is located on the circumferential flange or rim.

3. The rotational fixing of claim 2 wherein the friction enhancer is a knurled surface.

4. The rotational fixing of claim 3 wherein the knurled surface is provided on an end face of the circumferential flange or rim.

5. The rotational fixing of claim 3 wherein the knurled surface is provided on a circumferentially outer surface of the circumferential flange or rim.

6. The rotational fixing of claim 1 wherein the friction enhancer is located on the brake carrier.

7. The rotational fixing of claim 6 wherein the friction enhancer is a knurled surface.

8. The rotational fixing of claim 1 wherein the friction enhancer includes a washer disposed between the guide sleeve and the receiving portion.

9. The rotational fixing of claim 8 wherein the washer is a high friction washer.

10. The rotational fixing of claim 8 wherein the washer is a toothed washer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0036] FIG. 1 is an isometric view showing a disc brake according to the present invention with a preferred embodiment of the guide assembly;

[0037] FIG. 2 is an enlarged isometric cross-sectional view showing the preferred embodiment of the guide assembly;

[0038] FIGS. 3a, 3b and 3c are different views showing the sleeve of the preferred guide assembly;

[0039] FIG. 4 is a front view of the brake carrier showing the recess of the preferred guide assembly;

[0040] FIGS. 5a to 5g is a series of views showing how a circular cutting tool moves in a circular path to cut the first circular inner edge region of the recess of the preferred guide assembly;

[0041] FIGS. 6a and 6b is a front view of the brake carrier and an enlarged view showing the recess of the preferred guide assembly;

[0042] FIG. 7 is an exploded perspective view of the preferred guide assembly showing the guide pin and the brake carrier;

[0043] FIG. 8 is a top view of the preferred guide assembly showing the guide pin mounted on the brake carrier;

[0044] FIGS. 9a to 9c are schematic views showing the corresponding cross-sectional profiles of the sleeve portion and receiving portion for alternative embodiments of the guide assembly; and

[0045] FIGS. 9d to 9g are schematic views showing interconnections for alternative embodiments of the guide assembly.

DETAILED DESCRIPTION

[0046] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0047] Referring to FIGS. 1 to 9g, a disc brake according to the present invention is indicated generally at 1. The disc brake comprises a brake carrier 10. The brake carrier carries an inboard brake pad 12a and an outboard brake pad 12b. A rotor 14 (shown in part) is positioned between the brake pads and is rotatable about an axis R. A caliper 16 is slidably mounted with respect to the brake carrier by at least one guide assembly. In the embodiment depicted, the disc brake comprises two guide assemblies 18a, 18b. Each of the two guide assemblies is a guide assembly according to the preferred embodiment of the invention.

[0048] Each guide assembly comprises a guide pin 20 along which the caliper 16 can slide and a bore 22 disposed in the caliper for receiving the guide pin. In the embodiment depicted, one of the guide pins 20a is shorter than the other guide pin 20b in order to accommodate vehicle installation constraints.

[0049] The guide pin 20 comprises a fastener 24 to attach the guide pin to the brake carrier 10. The fastener is received by a complimentary bore 26 disposed in the brake carrier.

[0050] The guide pin 20 further comprises a sleeve 28 at least substantially surrounding the fastener 24 and over which the caliper 16 slides. The sleeve is a hollow, thin walled tube. The outer surface of the sleeve may be coated with PTFE (polytetrafluoroethylene) or any other suitable material to aid the sliding action of the caliper along the guide pin. The sleeve comprises a main body 30, a first end 32, a second end 34 and a bore hole 36 extending from the first end to the second end to receive the fastener.

[0051] The bore 22 disposed in the caliper to receive the guide pin is an elongate hole extending from a first side (inboard) to the second side (outboard) of the caliper 16.

[0052] During use, the guide pin 20 will be subject to dynamic loads. To counter rotational torque, the guide assembly of the present invention further comprises a rotational fixing to rotationally engage the sleeve 28 and the brake carrier 10 and thereby at least restrict rotation of the sleeve about its longitudinal axis. By rotationally engaging the sleeve and the brake carrier, the rotational fixing helpfully minimizes or avoids undesirable rotation of the sleeve.

[0053] By restricting the rotation of the sleeve relative to the brake carrier, the transmission of rotation from the sleeve to the fastener is also restricted. Thus, the subsequent risk of loosening the fastener from the brake carrier is advantageously reduced.

[0054] A rotational fixing for the disc brake may comprise a sleeve portion of the sleeve and a receiving portion of the brake carrier for receiving the sleeve portion. The sleeve portion may comprise an end portion of the sleeve, a circumferential flange or rim of the sleeve. The receiving portion may comprise a recess disposed in the brake carrier, a female member integrally formed or attached to the brake carrier or a male member protruding from the brake carrier.

[0055] The sleeve portion and the receiving portion may comprise corresponding non-circular cross-sectional profiles. As a consequence, the sleeve portion and receiving portion have a must-fit arrangement. The sleeve portion must be correctly aligned relative to the receiving portion for it to fit into the brake receiving portion. When the sleeve portion is located in the receiving portion, rotation of the sleeve relative to the brake carrier is restricted.

[0056] In the preferred embodiment of the guide assembly as shown in FIGS. 1 to 8, the sleeve portion of the rotational fixing is a circumferential flange 40 arranged at the first end of the guide sleeve. The cross-sectional profile of the flange is defined by an outer edge of the flange. In this embodiment, the flange has a non-circular cross-sectional profile comprising two profile regions. The profile of the flange has a first circular outer edge region 42 and a second flat outer edge region 44.

[0057] The desired cross-sectional profile of the flange may, for example, be manufactured by removing a segment of a circular flange of a conventional sleeve. The flange may be manufactured using any conventional cutting, milling or machining techniques, using for example a CNC (Computer Numerically Controlled) lathe or CNC milling machine. A cutting tool may be moved in a linear path to cut away the segment of the circular flange so as to form a flange with a first circular outer edge region and the second flat outer edge region. By way of example, a circular flange with a diameter of approximately 39.95 mm may be cut along a chord to remove a segment with a depth of approximately 1.75 mm such that the resulting flange has a first circular outer edge region with a radius of approximately 19.97 mm and a second flat outer edge region with a radius of approximately 18.25 mm

[0058] In the preferred embodiment of the guide assembly, the receiving portion of the rotational fixing is a recess 46 disposed in the brake carrier to receive the flange of the guide sleeve. The cross-sectional profile of the recess is defined by an inner edge of the recess. The inner edge has a corresponding non-circular cross-sectional profile to the flange. The non-circular cross-sectional profile of the recess comprises a first circular inner edge region 48 and a second flat inner edge region 50.

[0059] The flat inner edge region 50 of the recess may be located at any angular orientation with respect to the brake carrier. The flat inner edge region is preferably arranged in a low-stress region of the brake carrier. The orientation of the flat inner edge region may be determined by the orientation of the brake carrier with respect to the axle of the vehicle. In the preferred embodiment depicted in FIGS. 1 to 8, the flat inner edge region is arranged at a 6 o'clock orientation to the brake carrier.

[0060] The recess may be manufactured with the desired cross-sectional profile using any conventional cutting, milling or machining techniques, using for example a CNC lathe or CNC milling machine. The recess may be cut in the brake carrier by moving a cutting tool in a circular path to define the circular inner edge region. FIGS. 5a to 5g show how a rotating cutting tool may be moved sequentially in a circular path to cut a recess with the circular inner edge region. The rotating cutting tool may also be moved along a linear path to cut the flat inner edge region. By way of example, the recess may be cut in the brake carrier using a circular cutting tool with a diameter of 25 mm whereby the cutting tool may be moved along a circular path to cut a circular inner edge region with a radius of approximately 20 mm and the cutting tool may be moved along a linear path to cut a flat linear edge region with a radius of approximately 18.95 mm and a flat edge length of approximately 12.5 mm.

[0061] As the cutting tool moves from the circular path to the linear path and subsequently the linear path to the circular path, transition inner edge regions are formed between the circular inner edge region and the flat inner edge region. In the embodiment, the recess comprises a first transition inner edge region 52 at a first junction between the circular inner edge region and the flat inner edge region. As can be seen in FIG. 6b, the first transition inner edge region 52 is a curved corner extending between the first end of the flat inner edge region and the first end of the circular inner edge region. The recess also comprises a second transition inner edge region 54 at a second junction between the circular inner edge region and the flat inner edge region. The second transition inner edge region 54 is a curved corner extending between the second end of the flat inner edge region and the second end of the circular inner edge region.

[0062] The dimensions and configuration of the sleeve portion and recess are selected such that, when the sleeve portion is received and aligned in the recess, the first transition inner edge region 52 is able to abut the sleeve portion and thereby at least restrict the rotation of the sleeve portion in a first rotational directionfor example, the clockwise direction. The first transition inner edge region 52 preferably mates and abuts the sleeve portion at a first junction 56 between circular outer edge region 42 and the flat outer edge region 44.

[0063] Likewise, the second transition inner edge region 54 is able to abut the sleeve portion and thereby at least restrict the rotation of the sleeve portion in a second rotational directionfor example, the anti-clockwise direction. The second transition inner edge region 54 preferably mates and abuts the sleeve portion at a second junction 58 between the circular outer edge region 42 and the flat outer edge region 44.

[0064] The abutting action of the sleeve relative to the brake carrier depends on the tolerances, configuration and dimensions of the sleeve portion and recess. By way of example, the guide assembly may be configured to provide an abutting action that is able to restrict the rotation of the sleeve relative to the brake carrier to up to a maximum of approximately 10 degrees. The guide assembly may alternatively be configured to provide an abutting action that is able to restrict rotation to up to a maximum of approximately 5 degrees, to up to a maximum of approximately 3 degrees or up to a maximum of approximately 1 degree.

[0065] To enhance the mating contact between the sleeve portion and the transition regions of the receiving portion, the flange 40 may be chamfered at the junctions between the circular outer edge region 42 and flat outer edge region 44. The sleeve portion may comprise a first chamfered outer edge region 60 at the first junction 56 between the circular outer edge region 42 and the flat outer edge region 44 and a second chamfered outer edge region 62 at the second junction 58 between the circular outer edge region 42 and the flat outer edge region 44. The first chamfered outer edge region 60 improves the surface contact area between the flange 40 and the first transition inner edge region 52. The second chamfered outer edge region 62 improves the surface contact area between the flange 40 and the second transition inner edge region 54. By increasing the surface contact area, the abutting effect of the transition edge regions is improved and the rotation of the sleeve 28 is further restricted.

[0066] In the preferred embodiment of the guide assembly as shown in FIGS. 1 to 8, the fastener 24 for attaching the guide pin to the brake carrier is a threaded bolt and the bore 26 for receiving the fastener in the brake carrier is a threaded bore. The bore 26 is located in the recess 46 for receiving the sleeve portion. The bore may be centrally located or eccentrically located in the recess. The bore may be manufactured by any conventional drilling techniques.

[0067] To mount the guide pin on the brake carrier and rotationally engage the sleeve and the brake carrier, the bolt 24 is extended through the bore hole 22 of the sleeve, the flange 40 of the sleeve is located in the recess 46 with the profile regions aligned so as to form a rotational engagement between the sleeve and the brake carrier, and the bolt is screwed into the bore 26 in the brake carrier.

[0068] When attached to the brake carrier 10, the guide pin 20 extends in an axial direction A. Direction A is parallel to an axis R of rotation of the rotor 14 and parallel to the transverse axis of the disc brake. The caliper will be mounted on the guide pin by locating the guide pin in the caliper bore 22 and sliding the caliper along the guide pin sleeve.

[0069] When fully assembled, the disc brake as depicted in FIG. 1 can be actuated. An air actuator (not shown) is provided to move the inboard brake pad 12a into frictional contact with the rotor. When the inboard brake pad 12a is pushed towards and contacts the rotor, the caliper slides inboard along the guide pin. As the caliper slides inboard, it moves the outboard brake pad 12b towards the rotor. Hence, the rotor becomes clamped between the inboard and outboard brake pads and the rotation of the rotor is frictionally inhibited.

[0070] However, due to the corresponding non-circular cross-sectional profiles of the flange and recess, the disc brake can only be assembled or serviced if the profile regions of the flange and recess are properly aligned when first locating the flange in the recess. If the flange and recess are not properly aligned, the guide pin will not extend in the correct direction from the brake carrier. As a result, an operator will not be able to mount the caliper on the guide pin. Therefore, it is apparent that the flange and recess not only restrict undesirable rotation of the sleeve, they also usefully protect the disc brake from operator assembly error.

[0071] The sleeve portion and receiving portion of the rotation fixing may comprise any suitable corresponding non-circular cross-sectional profiles to at least restrict the rotation of the sleeve relative to the brake carrier. The corresponding non-circular cross-sectional profiles may comprise at least one circular region and/or at least one linear region, may have a regular and non-circular shape, may have an angular shape or a non-uniform shape.

[0072] In the alternative embodiment of the guide assembly depicted in FIG. 9a the sleeve portion 100 comprises a non-circular cross-sectional profile with a flat, linear edge 102. The receiving portion 200 is a recess disposed in the brake carrier with a corresponding non-circular cross-sectional profile with a flat, linear edge 202 to receive the sleeve portion. In the embodiment depicted in FIG. 9b, the sleeve portion 100 comprises a hexagonal cross-sectional profile 104. The receiving portion 200 is a recess disposed in the brake carrier with a corresponding hexagonal cross-sectional profile 204. In the embodiment depicted in FIG. 9c, the sleeve portion 100 comprises a free-form cross-sectional profile 106. The receiving portion 200 is a recess disposed in the brake carrier with a corresponding free-form cross-sectional profile 206.

[0073] The rotational fixing means may additionally or alternatively comprise an interconnection to interlock the sleeve and brake carrier so as to restrict rotation of the sleeve relative to the brake carrier. The interconnection may be locatable between a sleeve portion and receiving portion of a brake carrier.

[0074] The interconnection may comprise any suitable interconnection for rotationally engaging the sleeve and brake carrier. The interconnection may comprise a pin 300, for example as depicted in FIG. 9d. The sleeve portion 100 is received in the receiving portion 200. The pin 300 extends in axial direction A and the opposing ends of the pin are received in recesses formed in the sleeve portion and brake carrier 10. The interconnection may comprise a ball 302, for example as depicted in FIG. 9e. The sleeve portion 100 is received in the receiving portion 200. Opposing sides of the ball are received in semi-circular recesses formed in the sleeve portion and brake carrier 10. The interconnection may comprise a male protrusion and corresponding female indent. For example, as depicted in FIGS. 9f and 9g, the interconnection comprises one or more blades 304 or teeth 306 extending in axial direction A from the end of the sleeve portion 100 into corresponding indents in the brake carrier 10.

[0075] The rotational fixing means may comprise a deformable sleeve portion and a receiving portion for receiving the deformable sleeve portion. The deformable sleeve portion is configured to deform as it is located in the receiving portion so as to form an interference fit/press fit connection. Any rotation of the sleeve relative to the brake carrier is at least restricted due the interference fit/press fit connection.

[0076] The rotational fixing means may comprise a sleeve portion, a receiving portion to receive the sleeve portion and a friction enhancer to enhance the frictional engagement between the sleeve portion and receiving portion and thereby restrict rotation of the sleeve with respect to the brake carrier. The friction enhancer may comprise a knurled surface of the sleeve portion to enhance the frictional grip of the sleeve portion. The friction enhancer may comprise a splayed surface of the sleeve portion to help retain the sleeve portion in the receiving portion. The friction enhancer may comprise adhesive to bond the sleeve portion in the receiving portion. The friction enhancer may comprise a washer locatable between the sleeve portion and receiving portion. The washer may comprise a high friction washer and/or a toothed washer.

[0077] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.