Steering Column Outer Column Slit Design for Impact Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing steering column device structure, as described in JP2016-165935 (A), faces challenges in securing the strength of the outer column while maintaining processability due to the requirement of a long slit for processing, which compromises the strength of the outer column.
Innovation Solution
The steering column device incorporates an inner column, outer column, vehicle-body-side bracket, adjusting rod, pressing portions, expansion/contraction device, telescopic friction plate, release bracket, and support bracket, with a slit on the outer column and through holes in the sandwiched portions, allowing for relative displacement and impact absorption during secondary collisions without the need for a concave groove, enhancing processability and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a long slit is formed on the outer column to enable processing and adjustment, then the processability and adjustability are improved, but the strength of the outer column deteriorates
Solution Approach 1:
The outer column is segmented into multiple sections: a front-side portion, a rear-side portion, and a sandwiched portion between them. The slit is formed only in the sandwiched portion, allowing processing and adjustment while maintaining the strength of the front-side and rear-side portions. This segmentation enables the structure to be both processable and strong.
Solution Approach 2:
The slit is locally formed only in the sandwiched portion of the outer column, rather than throughout the entire column. This local quality change allows the sandwiched portion to be processed and adjusted while the front-side and rear-side portions maintain their full strength and structural integrity.
2Ease of manufacture
If a concave groove is formed on the outer column to secure length for processing, then the processability is improved, but the strength of the outer column deteriorates
Solution Approach 1:
The outer column is divided into distinct portions (front-side, sandwiched, rear-side) with the slit located only in the sandwiched portion. This segmentation eliminates the need for a concave groove while maintaining processing capability, as the slit in the sandwiched portion provides sufficient length for adjustment operations.
Solution Approach 2:
Instead of forming a concave groove in the radial dimension, the invention uses a longitudinal slit in the sandwiched portion that extends in the axial direction. This dimensional change allows processing to be performed along the length of the column rather than by removing material radially, preserving the column's strength.
3Object-affected harmful factors
If the inner column is released forward during secondary collision to allow steering wheel displacement, then the impact absorption is improved, but the structural stability deteriorates
Solution Approach 1:
The connection between the inner and outer columns is designed to be dynamic rather than rigid. The slit in the sandwiched portion allows the inner column to be released forward during secondary collision, enabling the steering wheel to displace and absorb impact. The structure transitions from a stable locked state during normal operation to a dynamic released state during collision.
Solution Approach 2:
The slit, which could be seen as a weakness compromising strength, is actually designed to enable the beneficial function of impact absorption. During secondary collision, the slit allows the inner column to release and move forward, converting the harmful impact force into beneficial energy absorption that protects the driver.
Data Source
AI summary
A steering column device has an inner column; an outer column combined with the inner column and having a slit extending in the axial direction, the inner column and the outer column configuring a telescopic steering column; a release bracket arranged inside the slit of the outer column and supported by and fixed to the inner column; a support bracket joined to the release bracket so as to be able to detach due to an impact load that is applied to the inner column during a secondary collision; and a telescopic friction plate having a function to increase a holding force for holding the steering column with respect to a vehicle-body-side bracket and supported by the support bracket.