Rotational Bellows for Disc Brakes

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Solution Overview

Problem

The existing bellows designs in disc brakes for commercial vehicles face issues with deformation and instability during extension, leading to frictional contact with adjacent components, leaks, and premature wear, especially when installation space is limited, resulting in reduced service life and increased maintenance costs.

Innovation Solution

A bellows design that maintains a circular contour even when stretched, with a specific axial distance between end rings and dimensioned flank heights to minimize deformation and stretching forces, ensuring stable operation and extended service life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the bellows is extended to compensate for large adjusting spindle travel distance, then the stroke capability is improved, but the flanks deform and buckle forming a polygonal shape that contacts adjacent components

Engineering Contradiction:
Improvestroke capabilityVSAvoidcircular contour stability
Core Design Contradiction:
Length of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies curvature principle by designing the flanks with a specific rounded contour shape rather than straight lines. The flank contour includes a first curve portion and a second curve portion that meet at an inflection point, creating a smooth curved surface that maintains circular stability during extension and prevents polygonal buckling.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Length of moving object

If the flank height is increased to achieve desired stroke, then the extension capability is improved, but the flanks become unstable and deviate from circular shape

Engineering Contradiction:
Improveextension capabilityVSAvoidsealing reliability
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The curved flank design with specific contour geometry distributes stresses more evenly during extension, preventing localized buckling that would compromise the sealing surface. The rounded profile maintains structural integrity while achieving the required extension stroke.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If the bellows is pressed into the sealing plate to ensure sealing, then the sealing function is improved, but the bellows becomes difficult to replace during maintenance

Engineering Contradiction:
Improvesealing functionVSAvoidreplaceability
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The bellows is designed as a separable component that can be independently removed from the sealing plate. The connection interface allows for tool-assisted extraction, enabling maintenance personnel to replace the bellows without damaging adjacent components while maintaining the pressed-fit sealing relationship during operation.

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 enhances the service life of the bellows by preventing deformation and contact with neighboring components, reducing the need for premature replacement and lowering operational costs due to reduced frictional forces and improved sealing efficiency.

Implementation Method 1

the bellows has several folds... the bellows is moved up to 4 mm in the axial direction during each braking action... the folds or their flanks are deformed, but in such a way that circular contours result

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

frictional contact with the adjacent surfaces occurs during the operating life of the disc brake... resulting in leaks forming

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3589867B1Bellows, and at least one disk brake having a bellows
Publication Date: 2023.11.15 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP3589867B1 patent drawingFigure 1
  • EP3589867B1 patent drawingFigure 2~3

AI summary

The invention relates to a rotationally symmetrical bellows (9), comprising a first end ring (12) and a second end ring (13) having a smaller diameter, and multiple folds (14), which in a relaxed position each have two flanks (15) running in opposite directions with respect to one another while forming a bend (16), which flanks extend approximately parallel to an axis of rotation (X) of the bellows (9). Said rotationally symmetrical bellows (9) is designed in such a way that in a relaxed position of the bellows (9), the second end ring (13) is arranged at an axial distance (a) to the first end ring (12).