Steering Column Segmentation for Dual-Collision Energy Absorption
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Solution Overview
Problem
Current steering devices face challenges in achieving sufficient energy absorption during both primary and secondary collisions, as the stroke length for primary collisions is often shortened when trying to lengthen it for secondary collisions, potentially compromising energy absorption capability.
Innovation Solution
A steering device design featuring a cylindrical inner column, outer column, and lower column, where the lower column moves rearward during primary collisions and the inner and outer columns move relative to each other during secondary collisions, with a shear pin mechanism to manage energy absorption and maintain stroke length for both types of collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stroke for secondary collision is lengthened by relative movement between lower column and intermediate column, then energy absorption capability at secondary collision is improved, but stroke for primary collision is shortened
Solution Approach 1:
The steering column is divided into functionally independent segments: the lower column handles primary collision energy absorption through rearward movement relative to the intermediate column, while the inner column handles secondary collision energy absorption through forward movement relative to the outer column. This segmentation allows each segment to optimize its stroke length for its specific collision type without compromising the other.
Solution Approach 2:
The shear pin acts as a mediator that connects the inner column to the inner column bracket, enabling controlled relative movement between these components during secondary collision. The shear pin shears off to allow the inner column to move forward, absorbing secondary collision energy, while not interfering with the lower column's rearward movement during primary collision.
2Reliability
If the stroke for primary collision is increased to improve energy absorption, then energy absorption capability at primary collision is improved, but the overall structural compactness is reduced
Solution Approach 1:
The steering column assembly is segmented into distinct functional zones: the lower column-intermediate column interface handles primary collision, while the inner column-outer column interface handles secondary collision. This segmentation allows the primary collision stroke to be optimized without increasing overall structural complexity, as each segment operates independently within its designated space.
Solution Approach 2:
The inner column is nested within the outer column, and the inner column bracket is nested within the outer column bracket structure. This nesting arrangement allows the secondary collision absorption mechanism to be compactly integrated within the primary collision mechanism, maintaining structural compactness while providing sufficient stroke for both collision types.
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
This design enhances energy absorption capability during both primary and secondary collisions by utilizing distinct mechanisms for each type of impact, ensuring effective energy dissipation and maintaining the steering wheel's operational range post-secondary collision.
Implementation Method 1
a shear pin that connects the inner column bracket to the inner column at a position across the first and second holes so that the inner column bracket and the inner column are detachable from each other
Implementation Method 2
the inner column is supported by a frictional force between the inner column and the outer column
Data Source
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AI summary
A steering device includes a cylindrical inner column that supports an input shaft connected to a steering wheel so as to allow the input shaft to be rotatable, a cylindrical outer column into which at least a part of the inner column is inserted, and a cylindrical lower column that supports an output shaft connected to the input shaft so as to allow the output shaft to be rotatable and is supported by a dash panel. The lower column moves to a rear side at the time of a primary collision, and the inner column and the outer column move relative to each other at the time of a secondary collision.