Slave Cylinder Piston Gap Structure for Clutch Seal Wear Reduction

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Solution Overview

Problem

Existing slave cylinder designs experience increased wear and surface quality issues due to vibrations transmitted from the rotating clutch, leading to potential seal damage and failure, especially when components are made from fiber-reinforced materials.

Innovation Solution

Incorporating an axial gap area with an undercut in the base body, which separates the seal's running section from the base body, reducing the likelihood of damage and wear by providing a distinct running path for the seal and the base body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the piston and seal are supported directly on the sleeve area without a gap, then the structure is simple and compact, but the seal is exposed to wear from vibrations and fiber exposure, leading to seal damage and failure

Engineering Contradiction:
Improveseal reliabilityVSAvoidbase body structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The base body is segmented into distinct functional areas: a sliding area that contacts the sleeve, a gap area that provides separation, and a holding area that secures the seal. This segmentation allows the seal to have its own dedicated running section on the sleeve that is spaced apart from the base body, preventing simultaneous contact and wear exposure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The gap area acts as an intermediary space between the sliding area and holding area, physically separating the seal's running section from the base body. This intermediary zone prevents direct exposure of the seal to worn fiber areas on the sleeve, reducing seal damage while maintaining structural integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If the piston is made from fiber-reinforced material for strength, then the structural strength is improved, but the wear effect is intensified as fibers are exposed during operation, damaging the seal

Engineering Contradiction:
Improvebase body strengthVSAvoidfiber exposure wear
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The harmful fiber exposure effect is extracted and isolated to the sliding area of the base body, which is separated from the seal by the gap area. The seal operates on a clean section of the sleeve that is not exposed to fiber wear, effectively removing the harmful interaction between fibers and seal while maintaining the strength benefits of fiber-reinforced material.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the gap area is made large to maximize seal protection, then seal damage is reduced, but the stable guidance of the piston during operation is compromised

Engineering Contradiction:
Improveseal protectionVSAvoidpiston guidance stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The gap area is optimized with specific dimensional characteristics: it is sufficiently large to provide adequate separation and protection for the seal, yet constrained to maintain proper piston guidance. The localized gap design ensures seal protection while preserving the stability of piston movement during operation.

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

This design significantly improves the operational reliability and wear behavior of the slave cylinder by reducing seal damage and maintaining stable guidance of the piston, even when wobbling movements occur, while being cost-effective and easy to produce.

Implementation Method 1

a fluidic pressure chamber (3) with the housing (2), the piston (4) being displaceably accommodated in the housing (2)

Methodology Applied
Scientific EffectHydraulic pressure transmission: Hydraulic Press

Data Source

PatentEP3749876B1Slave cylinder with piston, designed for wear reduction; actuation device; and coupling system
Publication Date: 2022.04.06 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3749876B1 patent drawingFigure 1~2
  • EP3749876B1 patent drawingFigure 3

AI summary

The invention relates to a slave cylinder (1) for a coupling confirmation device of a motor vehicle, comprising a housing (2) and a piston (4), which is received displaceably in the housing (2) and which together with the housing (2) delimits a fluidic pressure chamber (3). The piston (4) has a main body (6), which is guided slidingly along a sleeve region (5) of the housing (2), and a seal (7), which is attached to the main body (6) and seals the pressure chamber (3) with respect to the surrounding environment, the main body (6) having a gap region (10), which is distanced from the sleeve region (5) and which is arranged axially between a sliding region (8) supported on the sleeve region (5) and a holding region (9) receiving the seal (7). The invention additionally relates to an actuation device comprising this slave cylinder (1), and to a coupling system.