Patent Application
20200378457
The present invention relates to a disc brake. In addition, the present invention relates to a guide assembly for a disc brake, to a method for manufacturing a guide assembly and to a disc brake incorporating a guide assembly.
Disc brakes are commonly used for braking heavy vehicles such as trucks, buses and coaches.
Disc brakes conventionally comprise a brake carrier, a caliper and rotor. The brake carrier is arranged to carry brake pads on each side of the rotor. The caliper is slidably mounted on the brake carrier by two or more guide assemblies, such that when the disc brake is actuated, the caliper is able to slide with respect to the brake carrier. As the caliper slides inboard, the brake pads are urged onto the opposing faces of the rotor in a clamping action and a braking action is effected.
A guide assembly typically comprises a guide pin along which the caliper can slide and a bore disposed in the caliper for receiving the guide pin. Typically, each guide pin comprises a smooth outer sleeve along which the caliper slides and a bolt which extends through the sleeve and is screwed into a bore of the brake carrier to retain the sleeve.
This arrangement has been proven over many years of usage. However it has been recognized that in certain operating conditions, specifically when a vehicle undergoes a significant number of forward and reverse movements, there is a risk that the bolt of the disc brake may rotate and loosen.
Previous attempts to solve this problem have utilized lock patches to inhibit rotation of the bolt.
However, the present inventors have recognized that this approach in effect deals with a symptom of the problem rather than the cause. The present inventors have also identified that the cause of the loosening bolt problem is the rotation of the sleeve and the rotation of the sleeve being frictionally transmitted into rotation of the bolt.
The present invention seeks to overcome or at least mitigate the problems of the prior art.
A first aspect of the invention provides a rotational fixing to rotationally engage a guide sleeve and a brake carrier of a disc brake. By rotationally engaging the sleeve and brake carrier, the rotational fixing is able to at least impede rotation of the sleeve relative to the disc brake. Thus, the rotational fixing is able to at least restrict undesirable rotation of a sleeve caused by a changing torque as a vehicle moves repeatedly forwardly and backwardly. The transmission of rotation from the sleeve to the bolt and consequential loosening of the bolt is also restricted.
The rotational fixing for a disc brake may comprise: a sleeve portion of a guide sleeve; and a receiving portion of a brake carrier for receiving the sleeve portion; wherein the sleeve portion and receiving portion have corresponding non-circular cross-sectional profiles such that, when the sleeve portion is received and aligned in the receiving portion, rotation of the guide sleeve relative to the brake carrier is thereby at least restricted.
For the purposes of this present invention, a “non-circular cross-sectional profile” should be understood as meaning that the respective circumference of the sleeve portion and the receiving portion is not a complete circle. The corresponding non-circular cross-sectional profiles of the sleeve portion and the receiving portion may for example comprise a circular region and/or a linear region, may have a regular and non-circular shape, may have angular shape or a non-uniform shape.
The rotational fixing for a disc brake may comprise an interconnection to inter-engage a guide sleeve and a brake carrier and thereby at least restrict rotation of the guide sleeve relative to the brake carrier.
The rotational fixing for a disc brake may comprise: a deformable sleeve portion of a guide sleeve; and a receiving portion of a brake carrier to receive the sleeve portion; wherein the sleeve portion is deformable to be received and form an interference fit with the receiving portion such that rotation of the sleeve relative to the brake carrier is thereby at least restricted.
The rotational fixing for a disc brake may comprise: a sleeve portion of a guide sleeve; a receiving portion of a brake carrier to receive the sleeve portion; and a friction enhancer to enhance the frictional engagement between the sleeve portion and receiving portion, such that when the sleeve portion is received by the receiving portion, rotation of the guide sleeve relative to the brake carrier is at least restricted.
A second aspect of the invention relates to a guide assembly for a disc brake comprising: a guide pin comprising a sleeve with a sleeve portion; a receiving portion of a brake carrier to receive the sleeve portion; wherein the sleeve portion and receiving portion have corresponding non-circular cross-sectional profiles such that, when the sleeve portion is received and aligned in the receiving portion, rotation of the sleeve relative to the brake carrier is thereby at least restricted.
The sleeve portion of the sleeve may be a first end portion of the sleeve or a circumferential flange or rim at a first end of the sleeve.
The receiving portion of the brake carrier may be a recess disposed in the brake carrier. Alternatively, the receiving portion may be a female member integrally formed or attached to the brake carrier. The receiving portion may be a male member protruding from the brake carrier and configured to receive at least a part of the sleeve portion.
The non-circular cross-sectional profile of the sleeve portion may be defined by an outer edge of the sleeve portion. The sleeve portion may comprise a circular outer edge region and a non-circular outer edge region. The circular outer edge region may be part of a circle (i.e., an arc). The non-circular outer edge region may be linear, substantially flat or angled, or a chord.
Likewise, the non-circular cross-sectional profile of the receiving portion may be defined by an inner edge of the receiving portion. The receiving portion may comprise a circular inner edge region corresponding to the circular outer edge region of the sleeve portion and a non-circular inner edge region corresponding to the non-circular outer edge region of the sleeve portion. The circular inner edge region may be part of a circle (i.e., an arc). The non-circular inner edge region may be linear, substantially flat or angled, or a chord.
The non-circular inner edge region of the receiving portion may be located at any angular orientation with respect to the brake carrier. Preferably, it is arranged in a low-stress region of the brake carrier. This, in turn, may be dependent on the orientation in which the brake carrier is installed with respect to the axle of the vehicle.
The receiving portion of the brake carrier may further comprise a first transition inner edge region at a first junction between the circular inner edge region and the non-circular inner edge region. The first transition inner edge may, for example, be a first curved corner extending between a first end of a linear inner edge region and a first end of a circular inner edge region of the receiving portion.
To counter rotational torque acting on the sleeve in a first rotational direction, the first transition inner edge region may be configured such that, when the sleeve portion is received and aligned in the receiving portion, the first transition inner edge region is able to abut the sleeve portion so as to restrict rotation of the sleeve portion in the first rotational direction. For example, the first transition inner edge region may be configured to abut the sleeve portion so as to at least restrict rotation of the sleeve portion in a clockwise direction.
The sleeve portion of the sleeve may further comprise a first chamfered outer edge region at a first junction between the circular outer edge region and the non-circular outer edge region. The first chamfered outer edge region enhances the surface contact area between the sleeve portion and the first transition inner edge region and this, as a consequence, helps to further impede the rotation of the sleeve portion in the first rotational direction.
The receiving portion of the brake carrier may comprise a second transition inner edge region at a second junction between the circular inner edge region and non-circular inner edge region. The second transition inner edge region may, for example, be a second curved corner extending from a second end of a linear inner edge region to a second end of a circular inner edge region.
To counter rotational torque acting on the sleeve in a second rotational direction (opposite to the first rotational direction), the second transition inner edge region may be configured such that, when the sleeve portion is received and aligned in the receiving portion, the second transition inner edge region is able to abut the sleeve portion so as to restrict rotation of the second rotational direction. For example, the second transition inner edge region may be configured to abut the sleeve portion and thereby at least restrict rotation of the sleeve portion in an anti-clockwise direction.
To enhance the abutment of the sleeve portion by the second transition region and thereby further impede the rotation of the sleeve portion in the second rotational direction, the sleeve portion may further comprise a second chamfered outer edge region at a second junction between the circular outer edge region and the non-circular outer edge region.
To mount the guide pin on the brake carrier, the guide pin may comprise a fastener and the guide assembly may further comprise a bore disposed in the brake carrier to receive the fastener. Preferably, the fastener is configured to extend through the sleeve and the bore is arranged in the receiving portion. The bore may be arranged centrally or eccentrically in the receiving portion. The fastener may be a bolt, for example a threaded bolt and the bore disposed in the brake carrier may have a complimentary threaded bore.
The corresponding non-circular cross-sectional profiles of the sleeve portion of the sleeve and the receiving portion of the brake carrier not only help to restrict rotation of the sleeve but also advantageously help to minimize operator error when installing or servicing the disc brake. For example, if the operator fails to correctly align the corresponding non-circular regions of the sleeve portion and the receiving portion, but nevertheless tightens the fastener, the guide pin will not extend normal to the brake carrier as required. Thus, the operator will not be able to assemble the caliper because the guide pin will be out of alignment to the complimentary bore of the caliper.
A third aspect of the invention provides a disc brake comprising a brake carrier, a caliper and at least one guide assembly according to the second aspect of the invention for slidably mounting the caliper with respect to the brake carrier.
A fourth aspect of the invention provides a method for manufacturing a receiving portion of a brake carrier for receiving a sleeve portion of a guide sleeve. If the receiving portion is a recess disposed in the brake carrier, the method of manufacture may comprise cutting a recess in the brake carrier with a circular inner edge region and a non-circular inner edge region.
The method may further comprise: moving a cutting tool in a circular path to define the circular inner edge region; and moving the cutting tool in a non-circular path to define the non-circular inner edge region.
If the non-circular inner edge region is a linear inner edge region, then the non-circular path is a linear path.
The method may further comprise moving the cutting tool from the circular path to the non-circular path to define a transition inner edge region between the circular inner edge region and the non-circular inner edge region.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
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.
Referring to
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.
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.
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.
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.
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.
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.
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.
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.
In the preferred embodiment of the guide assembly as shown in
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
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.
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
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.
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
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 direction—for 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.
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 direction—for 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.
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.
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.
In the preferred embodiment of the guide assembly as shown in
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.
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.
When fully assembled, the disc brake as depicted in
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.
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.
In the alternative embodiment of the guide assembly depicted in
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.
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
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.
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15170690.0 | Jun 2015 | EP | regional |
This application is a continuation of U.S. application Ser. No. 15/174,102, filed Jun. 6, 2016, now abandoned, the disclosure of which is hereby incorporated in its entirety by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15174102 | Jun 2016 | US |
| Child | 16999610 | US |
