Disc Brake Pin Guiding Surface with Asymmetric Radial Clearance
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Solution Overview
Problem
Conventional motor vehicle disc brakes experience noise due to uncontrolled radial clearance between pins and their guiding bores, leading to shock and vibration during braking.
Innovation Solution
The disc brake design incorporates a cylindrical outer guiding surface on pins with angularly extended axial portions, where the median axial plane is parallel to the pins' axis plane, reducing radial clearance and using tubular sealing caps with flat sections and radial grooves to manage air decompression and dust tightness, allowing for identical pin usage and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If radial clearance is present between pins and guiding bores to enable sliding, then ease of operation is improved, but braking noise increases due to uncontrolled transverse movement
Solution Approach 1:
The pin guiding surface is divided into two distinct zones: a first axial portion with a first radial clearance that allows controlled sliding, and a second axial portion with a second radial clearance that is smaller than the first. This local differentiation enables the pin to slide smoothly during calibration while limiting transverse movement during braking to reduce noise.
Solution Approach 2:
The guiding surface of the pin is segmented into multiple axial portions with different clearance characteristics. The first axial portion (closer to the caliper) has larger clearance for sliding, while the second axial portion (closer to the cover) has smaller clearance for noise reduction. This segmentation allows simultaneous achievement of sliding capability and noise control.
2Ease of manufacture
If identical pins are used for both sides, then manufacturing cost is reduced, but precise control of radial clearance becomes more difficult
Solution Approach 1:
While identical pins are used on both sides for cost reduction, the bore structure is made asymmetric by providing different axial portions with different clearances. The first axial portion has larger clearance and the second has smaller clearance, creating an asymmetric clearance distribution that precisely controls pin movement characteristics while allowing use of identical pins.
Solution Approach 2:
Instead of controlling clearance through the radial dimension alone, the invention introduces an axial dimension by dividing the guiding surface into multiple axial portions. This dimensional approach allows precise control of clearance characteristics while maintaining pin identity, as the clearance control is achieved through axial positioning rather than radial precision alone.
Data Source
AI summary
A motor vehicle disc brake includes a cover with two tiered bores of parallel axes, each bore includes at least one first section; a caliper slidably mounted axially with respect to the cover by two pins of parallel axes rigidly connected to the caliper and each including at least one guiding section which is slidably mounted, with a radial clearance, in the tiered bore of the cover; and brake, wherein a cylindrical outer guiding surface of the sliding guiding section of each pin includes at least two opposed axial portions, extending angularly about the axis of each pin according to an angle less than 90°, a median axial plane of the two portions being parallel with a plane passing through the axes of the two pins.