Elastic Torque Transfer Joint for Misalignment and Backlash Noise
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Solution Overview
Problem
Existing torque transmission systems in electric power steering devices experience noise generation due to unavoidable backlash between the worm wheel and worm, despite spline-engagement without circumferential clearance, and oscillation of the worm to suppress noise leads to incomplete elimination of backlash.
Innovation Solution
A torque transmission joint with first and second rotating members featuring convex and recess portions, coupled by elastic bodies, allowing relative displacement and supported by a rigid coupling, to ensure smooth torque transmission and prevent noise even when central axes mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the worm is oscillated and displaced to suppress backlash at the meshing portion, then rattling noise is reduced, but backlash at the spline engagement portion cannot be completely eliminated
Solution Approach 1:
The coupling is segmented into multiple independent elastic pieces (first elastic pieces and second elastic pieces) arranged circumferentially. Each elastic piece independently absorbs displacement between the output shaft and worm, allowing the system to eliminate backlash at the spline engagement portion while maintaining the noise suppression effect from worm oscillation.
Solution Approach 2:
The elastic pieces are designed with specific rigidity characteristics that allow them to deform under circumferential load. By changing the rigidity parameter of these elastic pieces, the system can accommodate the worm's oscillation motion while preventing backlash at the spline engagement, resolving the contradiction between noise suppression and backlash elimination.
2Object-affected harmful factors
If spline engagement is performed without circumferential clearance, then abnormal noise at connection portion is eliminated, but backlash cannot be completely eliminated when worm oscillates
Solution Approach 1:
The elastic pieces act as intermediary elements between the output shaft and the worm. These intermediaries allow for controlled deformation that maintains tight spline engagement (eliminating abnormal noise) while accommodating the worm's oscillation motion, thereby preventing backlash without compromising the noise-free connection.
3Productivity
If a rigid coupling is used to ensure precise torque transmission, then torque transmission efficiency is improved, but noise generation occurs when central axes are misaligned
Solution Approach 1:
The coupling transitions from a rigid structure to a dynamic structure with elastic pieces that can deform. This dynamic characteristic allows the coupling to adapt to axis misalignment by deforming the elastic pieces, maintaining efficient torque transmission while eliminating noise that would occur with a rigid coupling under misalignment conditions.
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 enables seamless torque transfer between rotating members without generating abnormal noise, even when their central axes are misaligned, thereby enhancing the operational silence and efficiency of the system.
Implementation Method 1
a first elastic body having a plurality of first elastic pieces pinched in the circumferential direction between the respective first convex portions and the coupling; and a second elastic body having a plurality of second elastic pieces pinched in the circumferential direction between the respective second convex portions and the coupling
Data Source
AI summary
A torque transmission joint includes a first elastic body having a plurality of first elastic pieces pinched in a circumferential direction between respective first convex portions and a coupling, and a second elastic body having a plurality of second elastic pieces pinched in the circumferential direction between respective second convex portions and the coupling.