Steering Column Anti-Rotation Tab for Rivet Fatigue Control
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Solution Overview
Problem
The existing steering column assemblies face issues with fatigue and separation of energy absorbing rivets due to side-to-side force vectors applied during telescope motion, leading to degradation in collapse performance.
Innovation Solution
Incorporating a tab extending radially inwardly from the drive bracket, positioned within a slot on a plate, to prevent pivoting of the drive bracket, thereby countering lateral forces and maintaining the integrity of energy absorption components during telescoping and collapse events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the telescope drive bracket is allowed to pivot about the screw during telescope motion, then the actuator can provide motion transfer to the upper jacket assembly, but side-to-side force vectors are applied to the energy absorbing rivet causing fatigue loads and potential separation
Solution Approach 1:
The patent introduces an intermediary anti-rotation feature (such as a tab, protrusion, or mechanical stop) between the telescope drive bracket and the screw connection. This intermediary element prevents the bracket from pivoting about the screw while still allowing linear telescope motion to occur, thereby eliminating the harmful side-to-side force vectors applied to the energy absorbing rivet during normal operation.
2Reliability
If the drive bracket is rigidly connected to prevent any pivoting motion, then fatigue loads on the energy absorbing rivet are eliminated, but the complexity of the connection structure increases
Solution Approach 1:
The patent segments the connection structure by separating the functions of allowing linear motion from preventing rotational pivoting. The drive bracket connection is divided into components that independently handle axial telescope movement while a specific anti-rotation feature (tab, protrusion, or stop) specifically prevents pivoting motion, thereby maintaining simplicity while improving reliability.
3Reliability
If the tab extends radially inwardly within the slot to prevent pivoting, then the energy absorption functionality is maintained, but the manufacturing precision requirements increase
Solution Approach 1:
The patent designs the anti-rotation feature (tab and slot) with dynamic clearance and tolerance considerations. The tab extends radially inwardly within the slot to prevent pivoting, but the design incorporates appropriate clearances that accommodate normal manufacturing variations. The slot is dimensioned to provide sufficient constraint against pivoting while allowing for reasonable manufacturing tolerances, thereby balancing reliability with manufacturability.
Data Source
AI summary
A steering column assembly includes a column jacket. The column assembly also includes a drive bracket movable in a telescope direction, the drive bracket coupled to the column jacket to move the column jacket in the telescope direction. The column assembly further includes a plate operatively coupled to the column jacket and operatively coupled to the drive bracket, the plate defining a slot extending from an open end of the plate. The column assembly yet further includes a tab disposed within the slot to prevent pivoting of the drive bracket.