Cold-Formed Steel Brake Piston With Undercut Groove Bead Interface

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Solution Overview

Problem

Existing steel brake pistons face challenges in reducing construction effort and weight while maintaining effective interfaces for friction linings and springing mechanisms, with limitations in compatibility and tolerance variations.

Innovation Solution

The design features a cold-formed steel brake piston with a groove bead projection defining the minimum inner diameter, offsetting the minimum inner diameter towards the bottom, and a varying wall thickness ratio, allowing for a refined interface periphery that accommodates different friction lining tolerances and spring leg variations, eliminating the need for a radially inward angled edge arch and machining rework.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the piston wall thickness is reduced to minimize material mass, then the weight is reduced, but the structural strength and rigidity deteriorate

Engineering Contradiction:
Improvepiston weightVSAvoidpiston structural strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The piston features variable wall thickness with thicker sections at the base and end, and thinner sections in the middle. This local quality variation optimizes strength where needed while minimizing material mass in less critical areas, resolving the contradiction between weight reduction and structural strength maintenance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The piston wall is divided into multiple sections (base section, middle section, end section) with different thickness characteristics. The base and end sections have greater thickness for strength, while the middle section is thinner for weight reduction, creating a segmented thickness profile that balances both requirements.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the piston design is simplified to reduce construction effort, then the manufacturing complexity is reduced, but the interface compatibility with friction linings and springing mechanisms deteriorates

Engineering Contradiction:
Improvepiston construction complexityVSAvoidinterface compatibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The piston incorporates locally differentiated features such as the groove bead projection at specific locations and varying wall thickness sections. These localized features provide necessary interface compatibility for friction linings and springing mechanisms without requiring complex overall design, thus resolving the contradiction between simplicity and adaptability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The groove bead projection serves multiple functions: it defines the minimum inner diameter, provides a reference for friction lining installation, and creates a locking effect with spring struts. This multi-functionality reduces the need for additional separate features, simplifying the overall construction while maintaining interface compatibility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the minimum inner diameter is offset towards the bottom to create the groove bead projection, then the interface tolerance flexibility is improved, but the piston wall thickness distribution becomes more complex

Engineering Contradiction:
Improveinterface tolerance flexibilityVSAvoidwall thickness distribution complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The groove bead projection is formed during the cold-forming process itself, rather than requiring subsequent machining or assembly operations. This preliminary action integrates the tolerance-flexibility feature into the basic forming process, reducing overall construction complexity despite the sophisticated wall thickness distribution required.

Inventive Principle:
Principle #10Preliminary action

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 results in a lightweight, stable, and cost-effective brake piston with enhanced compatibility and tolerance flexibility, enabling easier replacement and installation of components with varying dimensions, while maintaining necessary rigidity and reducing material mass.

Implementation Method 1

The invention relates to a cold-formed steel brake piston 1 for a hydraulic disc brake 12

Methodology Applied
Scientific EffectCold-forming: Cold-forming

Data Source

PatentEP3471914B1Steel plate brake piston for a hydraulic brake
Publication Date: 2023.09.13 CONTINENTAL AUTOMOTIVE TECHNOLOGIES GMBH
  • EP3471914B1 patent drawingFigure 1~4
  • EP3471914B1 patent drawingFigure 2~3

AI summary

The invention relates to a pot-shaped cold-formed steel brake piston (1) as a pot that is open on one side and has a base (2) and a wall (3) including an inner and outer wall (4, 5), a radially inwardly formed groove (6) that is radially outwardly open and radially inwardly forms a groove bead protrusion (7), and wherein the open side of the pot terminates in a bearing for a friction lining back plate (11), and has internally integrated interfaces at the end which function a) for fixing between the friction lining and steel brake piston (1) and b) as a support bearing for spring cushioning the friction lining. The object of the invention is a further improved new generation steel brake piston (1). According to the invention, the object is achieved in that the minimum internal diameter (dimin) is set back in the direction of the base (2) at least by several times the length of a wall thickness (s), and in that the minimum piston inner diameter (dimin) is designed for forming an undercut from the groove bead protrusion.