Worm Shaft Holder Resilient Support for Steering Reducer

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Solution Overview

Problem

Conventional electronic power steering apparatus reducers experience clearance due to frictional wear between the worm and worm wheel, leading to rattle noise and inaccurate transmission of auxiliary steering force, exacerbated by torque changes.

Innovation Solution

A reducer design incorporating a worm shaft bearing, hollow bearing holder, holder housing, worm shaft holder, and resilient support to maintain clearance and reduce rotational friction, using materials like PTFE and nonlinear coil springs to minimize backlash and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional reducer design is used with worm and worm wheel, then power transmission is achieved, but clearance and rattle noise occur due to frictional wear and backlash

Engineering Contradiction:

Improveclearance preventionVSAvoidrattle noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A resilient support member is introduced as an intermediary element between the worm shaft holder and the holder housing. This resilient support member compensates for clearance caused by frictional wear and prevents backlash between the worm and worm wheel, thereby eliminating rattle noise while maintaining power transmission functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The resilient support member changes its physical state (elastic deformation) to dynamically compensate for clearance variations. By utilizing the elastic properties of the resilient support member, the system adapts to wear over time and maintains optimal clearance parameters without requiring mechanical adjustment.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If worm shaft is directly supported by bearing, then structural simplicity is maintained, but clearance changes occur due to torque variations

Engineering Contradiction:

Improvestructural simplicityVSAvoidclearance consistency

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The resilient support member provides dynamic adjustment capability to the worm shaft positioning system. Instead of a fixed rigid support, the resilient element dynamically adapts to torque variations by elastically deforming, thereby maintaining consistent clearance between the worm and worm wheel across different operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system utilizes elastic deformation of the resilient support member to change physical parameters (position, force distribution) in response to torque variations. This allows the clearance parameters to remain stable despite changes in operating torque, without requiring complex active control mechanisms.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If rigid support structure is used for worm shaft holder, then manufacturing precision is easier to achieve, but frictional wear causes clearance and instability

Engineering Contradiction:

Improveassembly precisionVSAvoidclearance stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The resilient support member introduces controlled elastic deformation to compensate for clearance generated by frictional wear. This allows the system to maintain stable operational parameters (clearance, positioning accuracy) over time without requiring extremely high manufacturing precision, as the resilient element absorbs dimensional variations and wear.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The resilient support member provides beforehand cushioning against the harmful effects of frictional wear. By incorporating this resilient element from the design stage, the system proactively compensates for clearance that would otherwise develop due to wear, preventing instability before it occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 effectively prevents clearance and noise, ensuring accurate steering wheel operation by maintaining consistent clearance and reducing rotational resistance, thereby enhancing the transmission of steering force.

Implementation Method 1

a resilient support coupled between the inner surface of the holder housing and the worm shaft holder to support the worm shaft holder in the direction of the worm wheel

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

using materials like PTFE and nonlinear coil springs to minimize backlash and noise

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8549945B2Reducer of electronic power steering apparatus

Publication Date: 2013.10.08 HL MANDO CORP

AI summary

A reducer of an electronic power steering apparatus is disclosed. The reducer of an electronic power steering apparatus aids the operation of a steering wheel by the driver by preventing a clearance from being caused by frictional wear between a worm and a worm wheel, by reducing rattle noise caused by backlash, and by minimizing the change in the clearance due to a change in torque.