Wear-Compensation Device for Assisted Steering Gears

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Solution Overview

Problem

Existing assisted-steering mechanisms for motor vehicles do not have means to limit gear wear over time, leading to inefficiencies and increased assembly operations.

Innovation Solution

A wear-compensation device featuring a fixed support, a rolling bearing, an eccentric, and a torsion spring that applies a circumferential preload force, allowing for automatic angular movement to compensate for gear wear, which is easy to manufacture, install, and requires minimal space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a wear-compensation device is added to the assisted-steering mechanism, then gear wear is compensated and system efficiency is maintained, but device complexity increases

Engineering Contradiction:

Improvegear wear compensationVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The wear compensation function is merged with the existing bearing support structure. The eccentric is mounted on the bearing outer ring, and the torsion spring is integrated between the fixed support and the eccentric, combining wear compensation with the bearing assembly into a unified structure that reduces overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The torsion spring automatically applies circumferential preload force to the eccentric, which self-adjusts to compensate for gear wear. The system uses its own internal components (spring, eccentric, bearing) to automatically maintain proper gear clearance without external adjustment mechanisms, achieving self-service wear compensation.

Inventive Principle:

Principle #25Self-service

2Reliability

If a wear-compensation device is added to the assisted-steering mechanism, then gear wear is compensated, but manufacturing and installation difficulty increases

Engineering Contradiction:

Improvegear wear compensationVSAvoidmanufacturing and installation ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The wear compensation device is segmented into distinct modular components: a fixed support that attaches to the housing, a bearing mounted on the worm shaft, an eccentric mounted on the bearing outer ring, and a torsion spring. This segmentation allows each component to be manufactured independently using standard processes and assembled through straightforward mounting operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of making the entire bearing assembly movable to compensate for wear, the invention inverts the approach by making only the eccentric movable on the fixed bearing. The eccentric rotates on the bearing outer ring while the bearing itself remains fixed on the shaft, simplifying manufacturing and installation compared to making the whole bearing movable.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If a wear-compensation device is added to the assisted-steering mechanism, then gear wear is compensated, but space requirement increases

Engineering Contradiction:

Improvegear wear compensationVSAvoiddevice space requirement

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The wear compensation components are nested within the existing housing and bearing structure. The eccentric is mounted on the bearing outer ring, which is already positioned within the housing. The torsion spring is nested between the fixed support and the eccentric, utilizing the existing spatial arrangement to minimize additional space requirements.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The wear compensation is achieved through angular/rotational movement of the eccentric on the bearing outer ring, utilizing the circumferential dimension rather than requiring additional axial or radial space. The torsion spring provides circumferential preload force, enabling the eccentric to rotate and adjust gear clearance without increasing the overall device volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 device effectively compensates for gear wear, reducing the need for frequent assembly adjustments and maintaining system efficiency with a compact and cost-effective design.

Implementation Method 1

a torsion spring mounted axially between the fixed support and the eccentric and capable of exerting a circumferential preload force on the said eccentric

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

an eccentric mounted on the bearing and designed to be in contact with the external element, the said eccentric being able to move angularly relative to the fixed support

Methodology Applied

Scientific EffectEccentric motion: Eccentric

Data Source

PatentUS8950280B2Wear-compensation device for a gear

Publication Date: 2015.02.10 AB SKF SKF PATENT DEPARTMENT

AI summary

The wear-compensation device for a gear comprises a fixed support capable of being fixed axially on an external element in order to keep the device on the said external element, a bearing designed to be mounted on a shaft comprising one of the wheels of the gear, an eccentric mounted on the bearing and designed to be in contact with the external element, the said eccentric being able to move angularly relative to the fixed support. The device also comprises a torsion spring mounted axially between the fixed support and the eccentric and capable of exerting a circumferential preload force on the said eccentric, the said spring comprising a first end mounted inside a recess of the eccentric and a second end interacting with the fixed support.