Steering Coupling Elastic Member for Axial Clearance and Vibration
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Solution Overview
Problem
Conventional electric power steering devices face challenges in adjusting axial clearance between the motor shaft and worm shaft, leading to misalignment and vibration in the worm gear due to high rigidity of the shock absorbing member, making it difficult to suppress torque variation and vibration.
Innovation Solution
A steering device with a coupling system comprising a first and second coupling member and an elastic member made from resin, featuring radially protruding blade portions and an axial elastic portion that is inclined to reduce rigidity and facilitate adjustment of axial clearance, allowing for effective transmission of rotation torque while minimizing vibration and torque variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the shock absorbing member is pressed in the axial direction to be compressed and deformed to adjust clearance, then the clearance between outer teeth member and inner teeth member can be adjusted, but the rigidity of the shock absorbing member becomes too high making it difficult to adjust axial clearance
Solution Approach 1:
The shock absorbing member is divided into multiple blade portions (first through fourth outer blade portions and corresponding inner blade portions) that can independently deform. This segmentation allows the member to be compressed axially for clearance adjustment while maintaining lower overall rigidity, as the segmented structure can flex more easily than a solid monolithic structure.
Solution Approach 2:
The shock absorbing member is designed with elastic blade portions that can dynamically deform under axial compression during assembly to adjust clearance, then maintain the adjusted position. The dynamic elasticity allows the member to be flexible during adjustment while providing stable shock absorption during operation.
2Reliability
If the shock absorbing member has high rigidity to absorb load variation, then load absorption capability is improved, but misalignment between motor shaft and worm shaft axes is generated causing vibration
Solution Approach 1:
Different portions of the shock absorbing member have different properties: the blade portions are designed with lower rigidity to accommodate misalignment and reduce vibration, while the base portions maintain sufficient rigidity to absorb load variations. This local differentiation of mechanical properties resolves the contradiction between load absorption and vibration suppression.
Solution Approach 2:
The shock absorbing member combines materials or structures with different mechanical properties - the blade portions use more flexible materials or thinner sections to reduce rigidity and accommodate alignment variations, while the base portions use stronger materials to maintain load absorption capability. This composite approach allows simultaneous achievement of both requirements.
3Manufacturing precision
If the shock absorbing member is compressed axially to adjust clearance, then axial clearance can be controlled, but torque variation is generated in the worm gear
Solution Approach 1:
Instead of solely relying on axial compression to adjust clearance, the invention uses the radial arrangement of multiple blade portions that can deform in both radial and axial directions. This multi-dimensional deformation capability allows clearance adjustment while distributing stresses more evenly, reducing torque variation in the worm gear.
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 reduces the rigidity of the elastic member, allowing for better alignment and reduced vibration and torque variation in the worm gear, enhancing the stability and efficiency of the steering device during motor operation.
Implementation Method 1
an elastic member which is made from a resin... the axial elastic portion which is provided to the elastic member base portion, and which is arranged to be bent in a direction to be inclined with respect to the first axis when a clearance between the first shaft member assembly and the second shaft member assembly in the direction of the first axis is decreased
Data Source
AI summary
A steering device includes: a coupling including a first coupling member, a second coupling member, and an elastic member, the elastic member which is made from a resin, and which includes an elastic member base portion, a first rotation direction elastic portion, a second rotation direction elastic portion, a third rotation direction elastic portion, a fourth rotation elastic portion, and an axial elastic portion, the axial elastic portion which is provided to the elastic member base portion, and which is arranged to be bent in a direction to be inclined with respect to the first axis when a clearance between the first shaft member assembly and the second shaft member assembly in the direction of the first axis is decreased.