Two-Part Disc Brake Piston for Lower Fluid Volume and Easier Venting

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Solution Overview

Problem

Existing disc brake pistons are heavy, require large amounts of hydraulic fluid, and are not easily vented, affecting responsiveness and manufacturing costs.

Innovation Solution

A two-part piston design with an outer and inner part, featuring fluid-tight connections to minimize hydraulic fluid usage and allow for a larger effective diameter, enhancing weight reduction and ease of venting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a single-part piston design is used, then structural simplicity is achieved, but weight increases and responsiveness decreases

Engineering Contradiction:
Improvepiston weightVSAvoidpiston structure
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The piston is divided into two separate parts: an outer piston body and an inner piston insert. The outer piston body provides the structural framework and braking surface, while the inner piston insert contains the hydraulic receptacle and is subjected to hydraulic pressure. This segmentation reduces the overall mass of the moving piston assembly while maintaining structural integrity and braking performance.

Inventive Principle:
Principle #1Segmentation

2Force

If a larger piston diameter is used, then braking force increases, but hydraulic fluid volume increases

Engineering Contradiction:
Improvebraking forceVSAvoidhydraulic fluid volume
Core Design Contradiction:
ForceVSQuantity of substance

Solution Approach 1:

The inner piston insert is nested within the outer piston body, with the inner insert containing the hydraulic receptacle. This nested configuration allows the hydraulic fluid to act only on the inner insert's cross-sectional area, while the outer piston body's larger diameter provides the braking force. Consequently, the volume of hydraulic fluid required is minimized while maintaining adequate braking force through the larger outer diameter.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Ease of manufacture

If a traditional piston design is used, then manufacturing is straightforward, but venting difficulty increases

Engineering Contradiction:
Improvepiston manufacturingVSAvoidventing ease
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The segmented piston design with the inner insert containing the hydraulic receptacle creates a compact configuration that facilitates venting. The receptacle can be designed with integrated vent channels or features that allow air bubbles to escape during brake bleeding operations, while the outer piston body maintains the braking surface and structural support.

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

The design results in lighter, more responsive disc brakes with improved braking performance and reduced material usage, allowing for cost-effective production.

Implementation Method 1

A cavity is formed between the outer part and the inner part, which cavity is sealed in a fluid-tight manner by at least one fluid-tight connection between the inner part and the outer part to prevent hydraulic fluid from entering the cavity from the receptacle of the inner part.

Methodology Applied
Scientific EffectFluid-tight sealing:

Implementation Method 2

via which the piston can be acted upon with a hydraulic fluid and/or with adjusting means of a parking brake drive

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4352375B1Piston for a disc brake, disc brake with at least one piston and series of pistons
Publication Date: 2025.08.20 ERDRICH UMFORMTECHN GMBH
  • EP4352375B1 patent drawingFigure 1
  • EP4352375B1 patent drawingFigure 2~3
  • EP4352375B1 patent drawingFigure 4~7

AI summary

The invention relates to improvements in the technical field of disk brakes. For this purpose, inter alia, a piston (1) for a disk brake is proposed, said piston comprising an outer part (4) and an inner part (5) inserted into the outer part (4), wherein a cavity (8) is formed between the outer part (4) and the inner part (5), which cavity is closed in a fluid-tight manner by at least one fluid-tight connection (9, 10) between the inner part (5) and the outer part (4) to prevent the ingress of hydraulic fluid.