Vehicle Disc Brake Pad Retention via Piston Abutment Projections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In opposed-piston-type vehicle disc brakes without hanger pins, friction pads can fall off when the lining wears down, as lug pieces drop into gaps between pad guide grooves and the disc rotor.
Innovation Solution
The back plate of the disc brake includes projections that abut the inner surfaces of the pistons, preventing the friction pad from falling by forming gaps between the piston surfaces and the projections, which do not impair piston sliding capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hanger pins are omitted to reduce production cost, then manufacturing cost is reduced, but friction pads may fall off when lining wears down
Solution Approach 1:
The patent introduces lug pieces as intermediary elements that engage with guide grooves in the caliper body to retain the friction pad. These lug pieces act as mediators between the friction pad and caliper body, providing retention functionality without requiring hanger pins. The lug pieces have protruding portions that fit into the guide grooves, preventing the friction pad from falling off while maintaining a simple and cost-effective structure.
2Device complexity
If lug pieces are accommodated in pad guide grooves without hanger pins, then device complexity is reduced, but lug pieces drop into gaps when back plate approaches disc rotor
Solution Approach 1:
The patent designs the guide grooves with specific geometric features that prevent lug pieces from dropping into gaps beforehand. The grooves are configured to maintain engagement with the protruding portions of the lug pieces even when the back plate approaches the disc rotor, providing preventive retention rather than reactive correction.
3Reliability
If projections are added on back plate to abut pistons, then friction pad retention is improved, but piston sliding capability may be impaired
Solution Approach 1:
The patent strategically positions projections on the back plate at specific locations where they abut the pistons to prevent friction pad fall-off, while carefully designing the projection geometry and placement to avoid interfering with piston sliding motion. The projections provide localized retention function without compromising the overall sliding capability of the pistons in the cylinder bores.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A vehicle disc brake includes a caliper body (3), pistons (6) and a pair of friction pads (4). The caliper body has a pair of operation arms and a bridge portion. Each operation arm has a cylinder bore (3e) and a pair of pad guide grooves (3i). The pistons are each inserted into the corresponding cylinder bore. Each friction pad has a lining and a back plate. Each friction pad further includes a pair of lug pieces (4a) and a projection. The lug pieces are accommodated in the pad guide grooves so that the friction pads are movable in an axial direction of a disc rotor. The projection (4d, 4e, 4f) is provided so as to be positioned inside an opening portion of the piston with a gap (E1)from an inner circumferential surface thereof.