Brake Retraction Spring Geometry for Even Pad Retraction

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Solution Overview

Problem

Existing brake assemblies face challenges in efficiently retracting brake pad assemblies due to uneven force distribution and potential misalignment, leading to uneven wear and potential damage.

Innovation Solution

The use of retraction springs with angled biasing arms and tips that engage with backplates, providing uniform forces to maintain parallel alignment and retract brake pads effectively, while preventing rotation and contact with the rotor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional retraction springs are used, then brake pad retraction is achieved, but uneven force distribution occurs leading to misalignment and uneven wear

Engineering Contradiction:
Improvebrake pad alignmentVSAvoiduneven wear
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The retraction spring employs angled biasing arms with different angles (first angle and second angle) relative to the rotor axis, creating non-uniform local force distribution that compensates for uneven wear patterns. The biasing arms are positioned at specific angles to apply targeted forces at different locations on the brake pad assembly, ensuring uniform retraction across the entire pad surface.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The retraction spring design incorporates asymmetric biasing arms where the first biasing arm and second biasing arm have different angular orientations. This asymmetric configuration allows the spring to counteract the natural tendency of brake pads to tilt or misalign during retraction, maintaining parallel alignment between opposing brake pad assemblies while preventing uneven wear through balanced force distribution.

Inventive Principle:
Principle #4Asymmetry

2Ease of manufacture

If simple retraction springs are used, then assembly is simple, but brake pads may contact the rotor causing damage

Engineering Contradiction:
Improveassembly simplicityVSAvoid rotor contact damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The retraction spring utilizes specific geometric parameters including the angles of the biasing arms relative to the rotor axis, the length and positioning of the biasing tips, and the spring constant of the coil spring. These parameters are carefully selected to ensure that the retraction force is sufficient to pull brake pads clear of the rotor surface while maintaining controlled motion to prevent impact damage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The biasing tips act as intermediary elements between the retraction spring and the brake pad assemblies. These tips engage with the brake pads at specific contact points, transmitting the retraction force in a controlled manner that prevents direct impact between the spring and the brake pads, thereby avoiding damage while ensuring effective retraction.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If retraction springs with angled biasing arms are used, then uniform force distribution is achieved, but device complexity increases

Engineering Contradiction:
Improveforce distribution uniformityVSAvoidspring structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retraction spring is segmented into distinct functional components: a central coil spring body and multiple biasing arms extending at different angles. Each biasing arm can be considered a separate element that independently contributes to the overall force distribution. This segmentation allows for optimized force application at different locations while maintaining a modular structure that is relatively simple to manufacture and assemble.

Inventive Principle:
Principle #1Segmentation

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 configuration ensures uniform force distribution across brake pad assemblies, maintaining parallel alignment and preventing tilting, thus reducing wear and damage, and facilitating efficient brake pad retraction.

Implementation Method 1

a retraction spring (400) having a coil (402) and adapted to impart a biasing force

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3736462B1Brake assembly having a retraction spring and method of assembly
Publication Date: 2024.01.17 ARVINMERITOR TECHNOLOGY LLC
  • EP3736462B1 patent drawingFigure 1
  • EP3736462B1 patent drawingFigure 2
  • EP3736462B1 patent drawingFigure 3

AI summary

A brake assembly having a retraction spring (200) and a method of assembly. The retraction spring (200) extends between first and second brake pad assemblies. The retraction spring includes a coil and has an end or tip that is received in a hole (82, 86, 92) in a backplate (70) of a brake pad assembly.