Railway Disc Brake Pad Structure for Static Friction and Disc Protection
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Solution Overview
Problem
Disc brakes for railway vehicles face issues with the formation of circular depressions on the disc, leading to damage of friction elements and a loss in static friction when using multiple friction elements, especially when coupled in elastic conditions.
Innovation Solution
A disc brake design featuring a pad with a combination of friction elements made from materials with different compressibility moduli, where sintered materials with higher compressibility are coupled elastically and organic materials with lower compressibility are coupled rigidly, arranged in arched rows to maintain effective static friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple friction elements are used instead of a single friction element, then braking effectiveness and noise reduction are improved, but circular depressions form on the disc causing damage to friction elements
Solution Approach 1:
The pad is divided into multiple friction elements (at least three) with different compressibility characteristics. Each friction element is segmented into distinct zones: a first friction element with higher compressibility and a second friction element with lower compressibility. This segmentation allows different portions of the pad to deform differently under load, distributing pressure more evenly across the disc surface and preventing the formation of circular depressions while maintaining effective braking contact.
Solution Approach 2:
Different regions of the pad are assigned different local properties through the use of friction elements with varying compressibility. The first friction element (higher compressibility) and second friction element (lower compressibility) create localized variations in pressure distribution. This local quality differentiation ensures that no single area concentrates excessive pressure that would cause disc depression, while collectively providing sufficient braking force.
2Adaptability or versatility
If friction elements are coupled in elastic condition using elastic elements, then adaptability to disc surface is improved, but static friction between pad and disc deteriorates
Solution Approach 1:
The compressibility parameter of the friction elements is changed and differentiated. By selecting materials with different compressibility characteristics for the first and second friction elements, the pad achieves optimal balance between adaptability and static friction. The higher compressibility element provides adaptability to disc surface irregularities, while the lower compressibility element maintains sufficient static friction for effective braking initiation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the static friction coefficient, ensuring the required levels of braking performance while preventing disc damage, by optimizing the elasticity of friction elements based on their compressibility.
Implementation Method 1
The first friction material has a compressibility modulus (pressure necessary to compress the material by 1 mm) greater than that of the second friction material
Data Source
AI summary
A disc brake for railway vehicles comprising a pad and a disc on which the pad acts. The pad comprises a base plate and a plurality of friction elements fixed to the base plate. The friction elements comprise first friction elements made with a first friction material and second friction elements made with a second friction material. The first friction material has a compressibility modulus greater than that of the second friction material by a value greater than or equal to 1 MPa. The first friction elements are in a higher number than the second friction elements. A respective elastic element is interposed between each of the first friction elements and the base plate, whereas a respective rigid spacer is interposed between each of at least part of the second friction elements and the base plate.