Steering Column Energy Absorbing Assembly with Segmented Strap
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Solution Overview
Problem
Existing energy absorption straps in steering column assemblies face challenges in packaging, load requirements, and tunability, leading to complex design issues and reduced performance during collapse events.
Innovation Solution
An axially adjustable steering column with a dual-jacket design and an energy absorbing assembly featuring a strap body with a curved portion and segmented apertures, allowing for adjustable connection points and enhanced energy dissipation through axial movement and a lock cam mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional roll straps are used with large gaps for strap travel, then strap deformation and energy absorption are enabled, but structural rigidity and strength are reduced
Solution Approach 1:
The strap is divided into multiple segments with apertures that can be selectively connected to the jacket using fasteners. This segmentation allows the strap to deform in controlled sections during impact while maintaining overall structural integrity through the distributed connection points along the jacket length.
Solution Approach 2:
The connection system allows dynamic adjustment of strap-to-jacket attachment points. During normal operation, multiple fasteners maintain rigid connection for strength. During impact, the dynamic loading causes selective fastener engagement/disengagement, allowing controlled deformation while preserving structural integrity through remaining connections.
2Strength
If material thickness and width are increased to maintain rigidity during collapse, then structural strength is improved, but packaging space and weight increase
Solution Approach 1:
Instead of using uniformly thick material throughout, the strap uses standard-thickness material with segmented apertures. The segmented connection system provides structural strength equivalent to thicker material while using less overall material volume, reducing packaging space requirements.
Solution Approach 2:
The strap has varying connection density along its length, with apertures and fasteners concentrated in regions requiring strength while allowing more deformation freedom in other regions. This localized quality optimization maintains strength where needed while minimizing material usage overall.
3Loss of energy
If the strap tail is allowed to feed out unimpeded to control absorption load, then energy absorption performance is improved, but packaging difficulty increases
Solution Approach 1:
The strap tail is segmented with additional apertures that can be connected to the jacket at controlled intervals. This segmentation allows the tail to feed out and deform for energy absorption while the distributed aperture connections prevent uncontrolled flailing and simplify packaging by containing the deformation within the jacket structure.
4Length of moving object
If the lower jacket is designed with large gaps for strap travel, then strap deformation is enabled, but added material is required to compensate for lost rigidity
Solution Approach 1:
The jacket-strap connection system transitions from static rigid attachment to dynamic selective attachment. During normal operation, multiple fasteners maintain rigid connection. During impact, the dynamic loading causes selective fastener engagement, allowing strap travel through the jacket gaps while the remaining connected portions maintain jacket rigidity without requiring additional material.
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 improves packaging efficiency, tunability, and load absorption capabilities, enabling more effective kinetic energy dissipation during impact events while maintaining structural integrity and reducing material requirements.
Implementation Method 1
roll straps absorb energy during the deformation of the strap in an impact event wherein kinetic energy can be dissipated through compression of the steering column assembly
Implementation Method 2
kinetic energy can be dissipated through compression of the steering column assembly
Data Source
AI summary
An axially adjustable steering column including a first jacket and a second jacket that is axially movable with respect to the first jacket. The second jacket includes a window and the first jacket includes a connector opening. An energy absorbing assembly includes a lock cam that is located in the window and connected to the second jacket and a strap body that is connected to the first jacket with a fastener extending through the strap body and the connector opening. The connector opening includes a ramp for ejecting the fastener from engagement with the first jacket.