Brake Pedal Metal Insert High Elastic Limit Steel

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Solution Overview

Problem

Existing brake pedals fail to maintain braking functionality during emergency braking when the thermoplastic material overmolding fails, as they lack sufficient strength to handle high forces, leading to a faulty braking mechanism.

Innovation Solution

A brake pedal design featuring a metal insert made of steel with an elastic limit greater than 500 MPa, surrounded by a reinforced thermoplastic material, ensuring the metal insert can maintain a minimum level of braking even if the thermoplastic material ruptures, with a high elastic limit steel insert providing resistance and a lightweight, low-density thermoplastic body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If thermoplastic material is used for the brake pedal body, then mass is reduced, but strength and reliability deteriorate under emergency braking forces

Engineering Contradiction:
Improvebrake pedal massVSAvoidbrake pedal strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The brake pedal combines thermoplastic material with a metal insert (steel sheet with elastic limit >500 MPa) to create a composite structure. The thermoplastic provides lightweight properties while the metal insert provides high strength and elastic resistance, resolving the contradiction between weight reduction and strength maintenance under emergency braking forces.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If thermoplastic material overmolding is used, then manufacturing cost is reduced, but reliability deteriorates when the material ruptures under high force

Engineering Contradiction:
Improvemanufacturing costVSAvoidbrake pedal reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The metal insert is pre-installed within the thermoplastic overmolding to provide a backup structural element. If the thermoplastic material ruptures under emergency braking forces, the metal insert maintains the structural integrity and braking functionality, providing beforehand cushioning against reliability failure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Weight of moving object

If sheet metal thickness is reduced, then mass is reduced, but strength deteriorates under very high braking forces

Engineering Contradiction:
Improvemetal insert massVSAvoidmetal insert strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent specifies a minimum thickness of 0.5 mm for the metal insert sheet, optimizing the balance between mass reduction and strength. Combined with the high elastic limit material (>500 MPa), this parameter change ensures sufficient strength under very high braking forces while minimizing mass.

Inventive Principle:
Principle #35Parameter changes

4Strength

If high elastic limit steel is used, then strength is improved, but manufacturing cost increases

Engineering Contradiction:
Improvemetal insert strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The high elastic limit steel is applied locally only where structurally critical - in the metal insert forming the lever structure - rather than throughout the entire brake pedal. This localized application of high-performance material provides necessary strength while controlling overall manufacturing cost.

Inventive Principle:
Principle #3Local quality

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

Ensures operating safety with a reduced mass brake pedal that can maintain degraded braking operation and reduce overall mass by approximately 40% compared to an all-metal pedal, while being more cost-effective and reliable than prior art designs.

Implementation Method 1

the steel with an elastic limit greater than 500MPa constitutes a material with a high elastic limit, designated by the acronym 'HLE', which gives the metal insert in the event of very high effort on the pedal resulting in a rupture of the thermoplastic molding, in particular during emergency braking, a resistance making it possible to ensure with this insert alone a degraded operation

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3360736B1Brake pedal for motor vehicle comprising a metal insert
Publication Date: 2020.02.26 PSA AUTOMOBILES SA
  • EP3360736B1 patent drawingFigure 1~3
  • EP3360736B1 patent drawingFigure 4~5

AI summary

The invention relates to a brake pedal for a motor vehicle, having at its base a support pad (4) and at its upper part a transverse pivot (6), this pedal comprising a metal insert formed in a cut sheet, arranged mainly in a plane perpendicular to the axis of the pivot (6), and a body (2) made by an overmolding in thermoplastic material surrounding the metal insert, characterized in that the sheet of the metal insert is made of a steel having an elastic limit greater than 500MPa.