Electric Power Steering Shaft Coupling Vibration Damping

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 spacers fail to absorb vibrations effectively.

Innovation Solution

A shaft coupling mechanism featuring a pair of rotation transmitting members and an intermediate interposed member with projecting portions of varying rigidity, where the intermediate member is elastically deformable to reduce impact transmission and prevent backlash, using hard resin for the transmitting members and a rubber-like material for the intermediate member to enhance 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 improves, but the spacer undergoes creep deformation and backlash occurs in the shaft coupling mechanism

Engineering Contradiction:

Improveimpact and vibration transmissionVSAvoidbacklash occurrence

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The coupling mechanism is divided into multiple functional components: hard resin rotation transmitting members for maintaining rigidity and preventing backlash, and a soft rubber intermediate member for absorbing vibrations. This segmentation allows each component to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the coupling mechanism have different material properties optimized for their specific functions. The rotation transmitting members use hard resin for rigidity and backlash prevention, while the intermediate member uses soft rubber for vibration absorption. This local differentiation of material qualities resolves the contradiction between softness and reliability.

Inventive Principle:

Principle #3Local quality

2Reliability

If the spacer is made harder to improve durability and prevent backlash, then the shaft coupling mechanism maintains precision, but impact and vibration are transmitted to the steering wheel causing uncomfortable steering feel

Engineering Contradiction:

Improvebacklash preventionVSAvoidimpact and vibration transmission

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coupling mechanism is divided into multiple functional components: hard resin rotation transmitting members for maintaining rigidity and preventing backlash, and a soft rubber intermediate member for absorbing vibrations. This segmentation allows each component to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the coupling mechanism have different material properties optimized for their specific functions. The rotation transmitting members use hard resin for rigidity and backlash prevention, while the intermediate member uses soft rubber for vibration absorption. This local differentiation of material qualities resolves the contradiction between softness and reliability.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If a single soft spacer is used to reduce vibrations, then impact transmission is reduced, but permanent deformation occurs due to repeated load causing backlash

Engineering Contradiction:

Improvevibration transmissionVSAvoidpermanent deformation

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The coupling mechanism is divided into multiple functional components: hard resin rotation transmitting members for maintaining rigidity and preventing backlash, and a soft rubber intermediate member for absorbing vibrations. This segmentation allows each component to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coupling mechanism uses a composite structure combining hard resin and soft rubber materials. The hard resin components provide structural stability and resistance to permanent deformation, while the rubber intermediate member provides vibration absorption. This composite approach allows the system to benefit from both material properties simultaneously.

Inventive Principle:

Principle #40Composite materials

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, prevents backlash, and enhances the durability and stability of the coupling mechanism, ensuring a comfortable steering feel and long-term performance.

Implementation Method 1

the pair of projecting portions of the intermediate interposed member has a smaller rigidity than the rigidity of the pair of projecting portions of each of the pair of rotation transmitting members and is elastically deformable

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS7699709B2Shaft coupling mechanism for electric power steering apparatus

Publication Date: 2010.04.20 OILES CORP

AI summary

A shaft coupling mechanism includes a coupling base body coupled to a rotating shaft; a coupling base body coupled to a steering shaft; rotation transmitting members which are disposed between the rotating shaft and the steering shaft through the both coupling base bodies and transmit the rotation of the rotating shaft in an R direction to the steering shaft; an intermediate interposed member disposed between the rotation transmitting members; and a coupling means for coupling the rotation transmitting members to each other.