Shaft Coupling Mechanism Reducing Vibration Transmission

Solution Overview

Problem

The existing shaft coupling mechanisms in electric power steering apparatuses face challenges in reducing impact and vibration transmission from the electric motor to the steering wheel, leading to uncomfortable steering feel due to potential backlash and durability issues, as softer spacers can deform and harder ones fail to absorb vibrations effectively.

Innovation Solution

A shaft coupling mechanism with coupling base bodies and a rotation transmitting member, where the latter has projecting portions with lower rigidity and is elastically deformable, reducing compressive deformation and backlash by integrating projections that contact the base bodies, thereby enhancing durability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the spacer is made softer to reduce impact and vibration transmission, then the steering feel comfort improves, but backlash occurs due to creep deformation from repeated loading

Engineering Contradiction:

Improveimpact and vibration transmissionVSAvoidbacklash occurrence

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The rotation transmitting member uses a composite structure combining a soft elastic body (such as rubber or resin) with embedded rigid reinforcing ribs. This composite design allows the soft material to absorb impact and vibration while the rigid ribs maintain structural integrity and prevent excessive deformation that would cause backlash.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rotation transmitting member has non-uniform local properties: the bulk material is soft and elastic for vibration absorption, while specific regions (reinforcing ribs) are made rigid to maintain dimensional stability. This local differentiation allows simultaneous achievement of vibration isolation and backlash prevention.

Inventive Principle:

Principle #3Local quality

2Reliability

If the spacer is made harder to improve durability and prevent backlash, then the steering feel precision improves, but impact and vibration are transmitted to the steering wheel

Engineering Contradiction:

Improvedurability and backlash preventionVSAvoidimpact and vibration transmission

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The rotation transmitting member uses a composite structure combining a soft elastic body (such as rubber or resin) with embedded rigid reinforcing ribs. This composite design allows the soft material to absorb impact and vibration while the rigid ribs maintain structural integrity and prevent excessive deformation that would cause backlash.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rotation transmitting member has non-uniform local properties: the bulk material is soft and elastic for vibration absorption, while specific regions (reinforcing ribs) are made rigid to maintain dimensional stability. This local differentiation allows simultaneous achievement of vibration isolation and backlash prevention.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If a soft spacer is used to reduce vibration, then the steering feel comfort improves, but the steering feel precision deteriorates due to backlash

Engineering Contradiction:

Improvesteering feel comfortVSAvoidsteering feel precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The rotation transmitting member uses a composite structure combining a soft elastic body (such as rubber or resin) with embedded rigid reinforcing ribs. This composite design allows the soft material to absorb impact and vibration while the rigid ribs maintain structural integrity and prevent excessive deformation that would cause backlash.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rotation transmitting member has non-uniform local properties: the bulk material is soft and elastic for vibration absorption, while specific regions (reinforcing ribs) are made rigid to maintain dimensional stability. This local differentiation allows simultaneous achievement of vibration isolation and backlash prevention.

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 effectively reduces the transmission of impact and vibration to the steering wheel, preventing uncomfortable steering feel and ensuring durability by minimizing backlash and creep deformation in the shaft coupling mechanism.

Implementation Method 1

the rotation transmitting member at least at its projecting portions having a smaller rigidity than the projecting portions of the one and the other coupling base bodies and being elastically deformable in the direction about the axis

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS7883423B2Shaft coupling mechanism for electric power steering apparatus

Publication Date: 2011.02.08 OILES CORP

AI summary

A shaft coupling mechanism for an electric power steering apparatus includes a coupling base body coupled to a rotating shaft; a coupling base body coupled to a steering shaft serving as a rotating shaft; and a rotation transmitting member which is disposed between the both coupling base bodies and transmits the rotation of the coupling base body in a direction about the axis, i.e., in an R direction, to the coupling base body as rotation in the R direction.