Single-Spring Shift Mechanism for Accurate Neutral Positioning

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Solution Overview

Problem

Conventional shift devices with spring systems suffer from reduced shifting accuracy due to differences in spring forces, high manufacturing tolerance requirements, and increased axial length, which complicates compact design and installation space optimization.

Innovation Solution

A shift device utilizing a single elastic member to transmit axial movement and restore the initial position of components in both axial directions, ensuring consistent positional accuracy and reducing installation space by using inner and outer sleeves with strategically placed abutments and an elastic member, such as a coil spring, to maintain precise alignment and prevent tilting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If two springs are used in the conventional spring system, then the shifting operation can be performed in both axial directions, but the neutral position is influenced by spring force differences and the axial length cannot be reduced

Engineering Contradiction:
Improveshifting operation in both axial directionsVSAvoidpositional accuracy of first member
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent merges the functions of two separate springs into a single elastic member. This elastic member can be compressed in either axial direction to allow relative movement between the first and second members, while providing a consistent neutral position that is not influenced by differences between multiple spring forces. The single elastic member design eliminates the need for precise matching of two separate springs while maintaining operational capability in both directions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The elastic member serves multiple functions: it allows relative axial movement in both directions, provides a restoring force to return members to their initial position, and establishes a consistent neutral position. This multi-functional design replaces the need for two separate springs with different force characteristics, simplifying the system while improving positional accuracy.

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

2Ease of operation

If two springs are sequentially arranged in the axial direction, then the shifting operation can be performed, but the axial length of the spring system increases

Engineering Contradiction:
Improveshifting operation capabilityVSAvoidaxial length of spring system
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The patent combines two separate springs into a single elastic member that performs the same shifting operation function. This consolidation reduces the axial length of the spring system while maintaining the capability to perform shifting operations in both axial directions. The single elastic member is arranged between the first and second members in a more compact configuration.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If two springs are used with different forces, then the shifting operation can accommodate different directions, but the neutral position becomes unstable and manufacturing tolerances must be very high

Engineering Contradiction:
Improveshifting operation in different directionsVSAvoidneutral position stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent merges two separate spring systems into a single elastic member that provides a stable, consistent neutral position. This single elastic member is designed to provide appropriate restoring forces in both axial directions without requiring precise matching of multiple components. The neutral position is determined by the geometry and pre-load of the single elastic member, making it more stable and less sensitive to manufacturing tolerances.

Inventive Principle:
Principle #5Merging (Combining)

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 ensures excellent shifting accuracy and reduces the required installation space for the spring system, preventing tilting and jamming while maintaining high elastic restoring forces, thus enhancing the overall performance and compactness of the shift device.

Implementation Method 1

By compression of the elastic member, a relative axial movement between the first member and the second member is allowed in both the first axial direction and the second axial direction opposite to the first axial direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the elastic restoring force of the elastic member urges the first member back to its initial position relative to the second member

Methodology Applied
Scientific EffectElastic restoring force: Elastic Recovery

Data Source

PatentEP4461997A1Shift device
Publication Date: 2024.11.13 ARVINMERITOR TECHNOLOGY LLC
  • EP4461997A1 patent drawingFigure 1
  • EP4461997A1 patent drawingFigure 2
  • EP4461997A1 patent drawingFigure 3

AI summary

A shift device is provided. The shift device comprises a first member axially movably supported on a shaft, a second member axially movably supported on the shaft, and an elastic member arranged on the shaft and elastically compressible in the axial direction of the shaft. The second member is engaged with the first member such that an axial movement of the first member is transmitted to the second member and vice versa via the elastic member. The elastic member, by being compressed, allows relative axial movement in both a first axial direction and the opposite second axial direction between the first member and the second member so that one of the first member and the second member is displaced from an initial position relative to the other of the first member and the second member. The elastic member, in a compressed state, exerts an urging force on the first member and the second member urging the one of the first member and the second member towards the initial position relative to the other of the first member and the second member.