Shaft Coupling Mechanism for Electric Power Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing shaft coupling mechanisms for electric power steering apparatuses suffer from collision noise and frictional noise due to axial relative displacement, and they may experience excessive elastic deformation of intermediate interposed members, leading to durability issues.
Innovation Solution
A shaft coupling mechanism with a first and second coupling base body and an intermediate interposed member, where the axial projecting portions of the coupling base bodies are spaced apart to avoid contact and the intermediate member has radial projecting portions with lower rigidity for elastic deformation, ensuring a secure contact area and preventing excessive deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the axial projecting portions of the coupling base bodies are made to contact each other to absorb axial relative displacement, then the brush vibration can be reduced, but collision noise and frictional noise occur
Solution Approach 1:
The intermediate interposed member is introduced as a mediator between the first and second coupling base bodies. It has a third axial projecting portion that contacts the first coupling base body and a fourth axial projecting portion that contacts the second coupling base body, enabling vibration absorption without direct contact between the coupling base bodies, thus eliminating collision and frictional noise.
Solution Approach 2:
The vibration absorption function is segmented into multiple components: the intermediate interposed member's third axial projecting portion absorbs vibration from the first coupling base body, while its fourth axial projecting portion transmits controlled motion to the second coupling base body. This segmentation allows vibration damping without the harmful direct contact between coupling base bodies.
2Object-affected harmful factors
If the intermediate interposed member undergoes large elastic deformation to absorb axial displacement, then vibration transmission is reduced, but excessive deformation leads to durability issues
Solution Approach 1:
The intermediate interposed member has different rigidity characteristics in different directions and locations. The radial projecting portions have lower rigidity to allow elastic deformation for vibration absorption, while the axial projecting portions maintain sufficient rigidity to transmit rotational motion reliably, ensuring both vibration reduction and durability.
Solution Approach 2:
The rigidity parameters of the intermediate interposed member are optimized: the radial projecting portions are designed with lower rigidity to permit controlled elastic deformation for vibration absorption, while the axial projecting portions maintain higher rigidity for reliable torque transmission, balancing vibration reduction and durability requirements.
3Object-generated harmful factors
If the axial projecting portions are spaced apart to avoid contact, then collision noise is eliminated, but the contact area with the intermediate member becomes small causing abnormal deformation
Solution Approach 1:
The intermediate interposed member serves as a mediator that distributes the contact load across its third and fourth axial projecting portions. This allows the first and second coupling base bodies to be spaced apart (eliminating collision noise) while maintaining sufficient contact area through the intermediate member's distributed contact points.
Solution Approach 2:
The contact interface is extended from a single-point contact between coupling base bodies to a distributed contact system involving the intermediate interposed member's axial projecting portions. This dimensional expansion of the contact interface provides sufficient contact area without requiring the coupling base bodies to be in direct contact.
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 eliminates collision and frictional noise, maintains durability by avoiding excessive elastic deformation, and ensures a stable contact area, enhancing the overall performance of the shaft coupling mechanism.
Implementation Method 1
it is impossible to reduce the transmission to the steering wheel of the brush vibration which causes axial relative displacement of one rotating shaft with respect to the other rotating shaft by causing axial elastic compressive deformation in radial projecting portions of the intermediate interposed member
Data Source
Figure 1~2
Figure 3
AI summary
A shaft coupling mechanism 1 for an electric power steering apparatus includes a coupling base body 3 coupled to a rotating shaft 2 on an electric motor side of an electric power steering apparatus; a coupling base body 5 coupled to a steering shaft 4 serving as a rotating shaft; and an intermediate interposed member 8 interposed between both coupling base bodies 3 and 5 and adapted to transmit the rotation of the rotating shaft 2 in an R direction to the steering shaft 4 in cooperation with both coupling base bodies 3 and 5.