Gearbox Stop Bushing Retention for Low-Vibration Neutral Positioning

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Solution Overview

Problem

Existing gear box control arrangements in automated manual transmission systems experience vibrations, noise, and deteriorated performance due to play between moving parts, which affect gear selection and maintenance.

Innovation Solution

Incorporation of an elastic retaining element, such as a spring washer, to constrain the axial movement of the annular stop bushing, reducing free movement and play, thereby minimizing vibrations and noise, and enhancing positioning accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an annular stop bushing is used to define the neutral position of the main piston, then the positioning function is achieved, but play between moving parts causes vibrations and noise

Engineering Contradiction:
Improvepositioning accuracy of neutral positionVSAvoidvibrations and noise
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

An elastic retaining element is introduced as an intermediary component between the stop bushing and the housing. This retaining element mediates the connection, providing both positioning function and vibration damping. The elastic material absorbs vibrations and prevents direct contact between rigid parts, thereby eliminating noise while maintaining positioning accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The elastic retaining element provides beforehand cushioning by being pre-installed in the housing to contact the stop bushing. This cushioning element is positioned in advance to absorb any potential vibrations and impacts before they can cause noise or damage, ensuring smooth operation throughout the device's lifetime.

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

2Adaptability or versatility

If multiple parts are arranged within the housing to enable gear selection, then the control function is achieved, but play between parts deteriorates performance over time

Engineering Contradiction:
Improvegear selection capabilityVSAvoidperformance stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The elastic retaining element acts as a mediator that stabilizes the stop bushing's position relative to the housing. By preventing play and unwanted movements, it ensures reliable gear selection and maintains performance stability throughout the device's operational lifetime.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The elastic retaining element changes the mechanical parameters of the system by introducing controlled elasticity. This elasticity allows for smooth, play-free movement of the stop bushing while maintaining precise positioning, thereby improving reliability without sacrificing adaptability.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If the stop bushing is allowed free axial movement, then the design is simple, but vibrations are generated due to play

Engineering Contradiction:
Improvestructural simplicityVSAvoidvibrations
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The elastic retaining element is a simple intermediary component that can be easily integrated into the existing housing structure. It eliminates vibrations caused by free axial movement of the stop bushing without significantly increasing device complexity, maintaining structural simplicity while solving the vibration problem.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The elastic retaining element utilizes flexible material properties to conform to the housing interior and provide continuous contact with the stop bushing. This flexible component prevents play and vibrations while adding minimal structural complexity to the overall design.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution reduces vibrations and noise, ensures a robust and compact design, minimizes part wear, and improves the accuracy of the neutral position of the pushrod.

Implementation Method 1

an elastic retaining element being arranged and adapted to exert a force, in an axial direction, on the stop bushing

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4421353B1Gear box control arrangement for an automated manual transmission system of a vehicle, in particular utility vehicle, automated manual transmission system, and vehicle, in particular utility vehicle
Publication Date: 2025.11.12 ZF CV SYST EURO BV
  • EP4421353B1 patent drawingFigure 1~3

AI summary

Gear box control arrangement (100) for an automated manual transmission system (250) of a vehicle (200a), in particular utility vehicle (200b), comprising a cover (115), a housing (105) for enclosing a main piston (135) and a pushrod (110) being movable by the main piston (135), an annular stop bushing (120) circumferentially enclosed by the housing (105) and adapted to define a neutral position (N), in an axial direction (A), of the main piston (135) within the housing (105), and an elastic retaining element (150) being arranged and adapted to exert a force (F), in the axial direction (A), on the stop bushing (120).