Patent Application
20070051568
The present invention relates to a disc brake and, more particularly, to a disc brake caliper slide pin having a tapered design.
Automotive components are typically exposed to a wide variety of environmental inputs including variations in temperature and load throughout operation of a vehicle. Use of a vehicle over rough surfaces provides a road load vibrational input as well. To assure proper operation of a vehicle component, it is desirable to maintain the structural integrity of the component or assembly for an extended time period.
Brake assemblies typically include a number of components interconnected to one another via threaded fasteners. To assure proper braking operation, it is desirable that the thread fasteners maintain a desired clamp load during and after exposure to the environmental and operational inputs previously discussed. Some bolted joints have experienced reduced clamp load or “backing-off” for a number of reasons. One reason relates to joint relaxation where a relatively short bolt or shaft is initially loaded to exhibit a relatively small elongation. If the bolt relaxes, the relatively small elongation is no longer present and the joint clamp load decreases. In addition, the clamping force generated by a threaded fastener may be insufficient if the surface area between any two components within the joint is insufficient to maintain the clamp load without yielding. In this case, relatively high contact stresses are generated between clamped components causing a portion of one of the clamped components to yield or flow when clamped. The yielding of the material reduces the fastener elongation and the clamp load is greatly decreased.
The present invention provides a disc brake having a tapered slide pin designed to maintain a desired location during operation of the brake and the vehicle.
In particular, the present invention relates to a disc brake operable to apply a clamping force to a rotatable disc. The disc brake includes a support bracket, slide pins coupled to the support bracket, inner and outer brake shoes and a caliper supported by the slide pins. The support bracket is a substantially rectangular frame defining a window. The window is adapted to accept a portion of a disc protruding therethrough. The support bracket includes a pair of spaced apart apertures extending through the frame where each aperture includes a threaded portion and a conical seat extending along an axis aligned to intersect the disc. The slide pins are threadingly engaged with a threaded portion. The slide pins do not extend through the window but protrude outwardly away from the window. Each slide pin has a tapered portion in engagement with one of the conical seats.
Additionally, the present invention relates to a disc brake having a disc rotatable about a laterally extending axis, a support bracket, slide pins coupled to the support bracket and a caliper slidably supported by the slide pins. The support bracket has first and second spaced apart, substantially parallel legs as well as third and fourth spaced apart, substantially parallel legs. The first and second legs are interconnected at their ends by the third and fourth legs to define a window. The first leg has spaced apart pin apertures where each pin aperture includes a threaded portion and a tapered portion extending along an axis. Each pin aperture is substantially parallel to the disc axis of rotation and radially positioned within the outer diameter of the disc. The slide pins have a threaded end and a tapered portion adjacent the threaded end. Each threaded end engages the threaded portion of one of the pin apertures. The tapered portion of each slide pin is driven into engagement with the tapered portion of each pin aperture by rotation of the slide pin relative to the support bracket. The caliper is slidably supported by the slide pins and includes a piston cavity for moveably supporting the piston. The piston cavity has an axis extending substantially parallel to and radially inward of the slide pin axes.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
With reference to
More particularly, brake support bracket 18 is a one-piece frame-shaped member preferably constructed by a casting or forging process. Support bracket 18 includes a first leg 30, a second leg 32, a third leg 34 and a fourth leg 36. First leg 30 is a substantially linear elongated member positioned substantially parallel to second leg 32. Second leg 32 is arched in a radial direction in relation to a laterally extending axis 38 about which disc 16 rotates. One end of first leg 30 is interconnected to one end of second leg 32 via third leg 34. The opposite ends of legs 30 and 32 are interconnected by fourth leg 36. First leg 30 includes a first detent 40 and a second detent 42.
Inboard brake shoe 12 includes a lining block 43 mounted on a backing plate 44. Backing plate 44 includes integrally formed tabs 46 and 48 protruding from each end. Detents 40 and 42 restrict inboard brake shoe 12 from radial movement but allow lateral movement of the brake shoe. Clips 50 may be inserted within detents 40 and 42 to assist in maintaining the proper position of inboard brake shoe 12 during operation. Second leg 32 includes a similar pair of detents 52 and 54. Outboard brake shoe 14 includes a lining block 55 mounted to a backing plate 56. Backing plate 56 includes integrally formed tabs 58 and 60 protruding from each end. Clips 62 cooperate with detents 52 and 54 to restrain tabs 58 and 60 from linear movement while allowing lateral movement parallel to axis 38.
First leg 30 includes a pair of brake mounting apertures 64 operable to receive brake fasteners to couple support bracket 18 to a knuckle or other vehicle suspension component. Caliper 24, inboard brake shoe 12 and outboard brake shoe 14 are supported via this structural interconnection. Support bracket 18 also includes a first slide pin aperture 66 and a second slide pin aperture 68. Slide pin aperture 66 extends laterally through first leg 30 along a first slide pin axis 69. Slide pin aperture 66 includes an internally threaded portion 70 and a tapered portion 72. Slide pin 20 is threadingly engaged with pin aperture 66 and protrudes laterally inboard along axis 69.
As best shown in
Caliper 24 includes a pin bore 100 in receipt of first slide pin 20. A running-class fit exists between outer cylindrical surface 76 of first slide pin 20 and pin bore 100 to allow caliper 24 to translate laterally relatively to support bracket 18 during operation. Bellows 92 is operable to axially extend and compress to account for the relative movement between caliper 24 and support bracket 18. A cap 102 engages boss 98 and covers pin bore 100. Cap 102 is removable to allow access to drive recess 88 should brake service and removal of first slide pin 20 be required.
Caliper 24 is a generally “C” shaped member having an inboard side portion 104 and an outboard side portion 106 interconnected by a laterally extending bridge portion 108. First side portion 104 includes boss portion 98 as well as another boss portion 109 substantially similar to boss 98. Furthermore, first side portion 104 includes a first piston bore 110 and a second piston bore 112. First piston 26 is slidably positioned within first piston bore 110 to move along a first piston bore axis 113. A first piston seal 114 sealingly engages first piston 26 and first side portion 104 to protect the piston bore from ingress of contamination. Similarly, second piston 28 is slidably positioned within second piston bore 112 to move along a second piston bore axis 115. A second piston seal 116 sealingly engages second piston 28 and first portion 104. First piston 26 and second piston 28 are operable under hydraulic fluid pressure entering a port 118 to apply a force to backing plate 44 of inboard brake shoe 12.
Outboard side portion 106 includes a surface 120 in engagement with backing plate 56 of outboard brake shoe 14. A pair of cut-outs 122 extend through outboard side portion 106 to allow tooling (not shown) sufficient access to form first piston bore 110 and second piston bore 112. Outboard side portion 106 is laterally positioned between first leg 30 and second leg 32 of support bracket 18. Because inboard brake shoe 12, outboard brake shoe 14 and caliper 24 are laterally moveable relative to support bracket 18 and disc 16, both inboard brake shoe 12 and outboard brake shoe 14 may clamp against disc 16.
With reference to
Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.
