Electric Power Steering Shaft Coupling Vibration Absorption
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Solution Overview
Problem
Existing shaft coupling mechanisms for electric power steering systems face issues with collision noise, frictional noise, and durability due to axial relative displacement and excessive elastic compressive deformation, which affect the steering feel and durability.
Innovation Solution
A shaft coupling mechanism with specific axial and radial projecting portions and an intermediate interposed member of varying rigidity, designed to absorb axial relative displacement and prevent contact between projecting portions, ensuring a stable contact area and reducing elastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the spacer is made softer to reduce impact and vibration, then the impact and vibration transmission is reduced, but the spacer undergoes creep deformation causing backlash
Solution Approach 1:
The invention changes the rigidity parameter of the intermediate interposed member by positioning it only in the radial direction while maintaining rigidity in the axial direction through the coupling base bodies. This allows the member to absorb radial vibrations through elastic deformation while preventing axial creep deformation that causes backlash.
Solution Approach 2:
The invention applies different mechanical properties to different directions: the intermediate interposed member is designed to be elastic in the radial direction for vibration absorption, while the coupling base bodies provide axial rigidity to prevent backlash. This directional differentiation of mechanical properties resolves the contradiction between vibration reduction and backlash prevention.
2Reliability
If the spacer is made harder to improve durability and prevent backlash, then backlash is reduced, but impact and vibration are transmitted to the steering wheel
Solution Approach 1:
The invention changes the rigidity parameter distribution by making the intermediate interposed member elastic in the radial direction for vibration absorption while maintaining axial rigidity through the coupling base bodies, preventing both backlash and excessive vibration transmission.
Solution Approach 2:
The invention applies different mechanical properties to different directions: radial elasticity in the intermediate member for vibration reduction, and axial rigidity in the coupling base bodies for backlash prevention, simultaneously achieving both durability and comfort.
3Stability of the object's composition
If the projecting portions are made to contact the base portion to absorb axial displacement, then axial displacement is absorbed, but collision noise and frictional noise occur
Solution Approach 1:
The invention introduces the intermediate interposed member as a mediator between the rotation transmitting members, positioned in the radial direction to absorb vibrations without causing axial contact between projecting portions and base portions, thereby eliminating collision and frictional noise while maintaining displacement absorption.
Solution Approach 2:
The invention shifts the vibration absorption function from the axial dimension (where contact causes noise) to the radial dimension (where elastic deformation absorbs vibration without contact noise), by positioning the intermediate interposed member radially between the coupling base bodies.
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 mechanism effectively eliminates collision and frictional noise, maintains durability by preventing excessive elastic deformation, and ensures a stable contact area, enhancing the steering feel and system longevity.
Implementation Method 1
an intermediate interposed member which is interposed between this pair of rotation transmitting members... the radial projecting portions of the intermediate interposed member having a smaller rigidity than the rigidity of the axial projecting portion and the radial projecting portion and being elastically deformable
Implementation Method 2
the radial projecting portions of the intermediate interposed member having a smaller rigidity than the rigidity of the axial projecting portion and the radial projecting portion and being elastically deformable... making it possible to reduce the transmission to the steering wheel of the impact at the time of the reversing of the electric motor and the brush vibration
Data Source
AI summary
A shaft coupling mechanism for an electric power steering apparatus includes a coupling base body coupled to a rotating shaft on a side of an electric motor; a coupling base body coupled to a steering shaft; rotation transmitting members interposed between both coupling base bodies and adapted to transmit the rotation of the rotating shaft in an R direction to the steering shaft through both coupling base bodies; an intermediate interposed member interposed between the coupling base bodies; and a coupling means for coupling the rotation transmitting members to each other.