Steering Column Strap Assembly With Metal Breakaway Pin
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Solution Overview
Problem
Existing energy absorption strap systems in vehicle steering columns often break away at too low a load due to the use of plastic pins, which is inadequate for many applications, requiring a higher breakaway load to effectively absorb occupant mass during a collapse event.
Innovation Solution
Incorporating a metal rivet or pin that extends through both legs of the energy absorbing strap, forming a U-shape, which provides a higher breakaway load of 1200 N to 1800 N by resisting unrolling and avoiding shearing, thus enhancing the energy absorption capability during a collapse event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a metal pin is used to extend through both legs of the strap, then the breakaway load increases to 1200 N to 1800 N, but the component complexity increases
Solution Approach 1:
The patent combines the pin function with the strap structure by extending the metal pin through both legs of the U-shaped strap, creating an integrated component that serves multiple functions: structural connection, load bearing, and controlled breakaway mechanism. This merging reduces the need for separate components while achieving the desired breakaway load.
2Force
If the metal rivet does not extend into the upper jacket, then the breakaway load increases, but the anchoring strength decreases
Solution Approach 1:
The patent applies local quality by positioning the metal rivet to extend through both legs of the strap but deliberately not extending into the upper jacket. This localized configuration creates a controlled weakness point that enables the desired breakaway behavior at a specific location while maintaining strength elsewhere in the assembly.
Data Source
AI summary
A steering column assembly includes a lower jacket. The steering column assembly also includes an upper jacket in telescoping engagement with the lower jacket. The steering column assembly further includes an energy absorbing strap assembly operatively coupled to the upper jacket. The energy absorbing strap assembly includes a strap having a stationary leg and a moveable leg connected by a curved portion to form a substantially U-shape. The energy absorbing strap assembly also includes a metal pin extending through the stationary leg and the moveable leg.