Torque Transmission Joint With Elastic Buffering for EPS Backlash Noise
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Solution Overview
Problem
Existing electric power steering devices experience abnormal noise generation when reversing the rotational direction of the driving shaft due to backlash in the spline engagement portion between the output shaft of the electric motor and the worm shaft, which is not effectively suppressed by conventional noise reduction methods.
Innovation Solution
A torque transmission joint is designed with a driving-side transmission member, a driven-side transmission member, and an intermediate transmission member, each featuring concave-convex portions and an elastic member that covers the intermediate transmission member, allowing for controlled engagement with circumferential gaps to reduce noise through elastic deformation and buffer functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worm shaft is allowed to swingably displace to reduce backlash, then gear meshing quality improves, but the spline engagement backlash cannot be completely removed
Solution Approach 1:
The torque transmission joint acts as a mediator between the output shaft and worm shaft. It includes an intermediate transmission member with elastic elements that compensate for spline engagement backlash while allowing the worm shaft to swing for proper gear meshing, thus resolving both requirements simultaneously.
Solution Approach 2:
The elastic members in the torque transmission joint provide beforehand cushioning by pre-absorbing the backlash in the spline engagement portion. This cushioning effect is prepared in advance to prevent abnormal noise when reverse rotation occurs, while not interfering with the necessary swingable displacement of the worm shaft.
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 suppresses abnormal noise generation during rotational direction reversal by weakening contact forces through elastic deformation and providing a buffer against misalignment, enhancing the operational feel of the steering wheel.
Implementation Method 1
an elastic member that covers an axial side surface of the intermediate transmission member... weakening contact forces through elastic deformation
Data Source
AI summary
A driving-side concave-convex portion of a driving-side transmission member is engaged with an elastic member. The driving-side concave-convex portion is engaged with an intermediate concave-convex portion of an intermediate transmission member with a circumferential gap being interposed therebetween. A driven-side concave-convex portion of a driven-side transmission member is engaged with the elastic member. The driven-side concave-convex portion is engaged with the intermediate concave-convex portion with a circumferential gap being interposed therebetween. Both axial side surfaces and a periphery of the intermediate transmission member are covered by a side surface covering portion and a periphery covering portion of the elastic member.