Steering Column Energy Absorbing Assembly Design
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Solution Overview
Problem
Existing energy absorption features in steering column assemblies face challenges in packaging, load requirements, and tunability due to complex configurations and loss of rigidity, particularly with roll straps and their associated locking cams and cam springs.
Innovation Solution
An energy absorbing assembly is introduced, featuring a lock cam with a toothed portion, a bumper with loops, and a pivot pin, along with a cam spring that biases the lock cam, allowing for improved energy dissipation and reduced complexity in the steering column's packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a long channel is used to allow strap travel, then the strap can move freely for energy absorption, but the structure loses rigidity and requires added material
Solution Approach 1:
The long channel is divided into multiple discrete linkages connected by pins, allowing the strap to travel through a segmented path while maintaining structural integrity. Each linkage segment can rotate independently, providing the necessary strap travel without requiring a continuous long channel that would compromise rigidity.
Solution Approach 2:
The linkages are arranged in a nested configuration where smaller linkage segments are positioned within or alongside larger structural components. This allows the strap travel path to be compacted into the existing structural envelope, eliminating the need for additional material to compensate for lost rigidity.
2Ease of operation
If space is made for a tail of the strap to feed out unimpeded, then the absorption load can be controlled, but packaging difficulties arise
Solution Approach 1:
The strap tail is guided through a three-dimensional path using vertically arranged linkages and pins, rather than a simple linear extension. This dimensional approach allows the strap to feed out unimpeded for load control while containing the mechanism within a compact vertical envelope that fits within the steering column housing.
3Reliability
If a complicated series of non-integral stiffening brackets and guides is used, then the strap is retained properly, but the device complexity increases
Solution Approach 1:
Multiple separate components (stiffening brackets, guides, and retention features) are merged into an integrated linkage assembly. The linkage itself provides both the guiding function and the retention function, eliminating the need for separate non-integral brackets and guides while maintaining proper strap retention through the pinned connection points.
4Force
If a small and complicated wire-form cam spring is used, then the locking cam is biased, but the manufacturing complexity increases
Solution Approach 1:
The complicated wire-form cam spring is replaced with a simpler, more manufacturable spring design that may be less durable but is significantly easier and cheaper to produce. The invention accepts reduced spring life in exchange for dramatically improved manufacturability and reduced assembly complexity.
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 solution enhances energy absorption efficiency while simplifying the design, improving tunability and reducing material requirements, thus addressing the limitations of existing systems.
Implementation Method 1
a cam spring operably connected to the lock cam... and the lock cam biased by the cam spring in a pivot direction
Implementation Method 2
These energy absorbing 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
Data Source
AI summary
A steering column with an energy absorbing assembly. The steering column comprising a first jacket and a second jacket that is axially movable with respect to the first jacket. The second jacket includes a window. The energy absorbing apparatus includes a lock cam located in the window and connected to the second jacket and a strap body that is connected to the first jacket. The lock cam includes a toothed portion for selective engagement with the strap body. The energy absorbing apparatus includes at least one of a cam spring located between the lock cam and an edge of the window or a bumper.