Steering Column Energy Absorption Strap with Tunable Breakaway Load
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Solution Overview
Problem
Existing vehicle steering column energy absorption systems face challenges in achieving a targeted breakaway load profile and require flexibility to adjust load levels and profiles, with current designs often failing to meet customer specifications and being costly to modify.
Innovation Solution
The energy absorption strap assembly features a strap with a stationary and moveable leg, and a pin extending through both legs to resist unrolling, allowing for customization of the breakaway load and profile by adjusting the pin's size and material, along with geometric parameters of the strap segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a pin is pressed through one portion of the EA strap to satisfy low initial breakaway load requirement, then the breakaway load requirement is met, but the targeted load profile cannot be achieved in some applications
Solution Approach 1:
The patent applies parameter changes by varying the pin's material properties (such as hardness, tensile strength) and geometric parameters (diameter, length) to precisely control the breakaway load and load profile. This allows customization of the energy absorption characteristics to meet specific customer requirements while maintaining manufacturing feasibility.
Solution Approach 2:
The EA strap is segmented into multiple portions with different structural characteristics, and the pin is strategically positioned to interact with specific segments. This segmentation allows different regions of the strap to contribute differently to the load profile, enabling precise control over the energy absorption characteristics.
2Adaptability or versatility
If the breakaway load level and profile are adjusted to meet customer specifications, then customer requirements are satisfied, but the adjustment is costly and time-consuming
Solution Approach 1:
The patent enables cost-effective adjustment of breakaway load levels and profiles by changing parameters of existing components rather than redesigning the entire system. By selecting different pin materials and dimensions, or modifying strap geometry parameters, customers can achieve customized load profiles without incurring high retooling or redesign costs.
Solution Approach 2:
The EA strap design incorporates universal features that allow it to serve multiple applications with different load requirements. The same basic strap structure can be adapted to various breakaway load specifications by simply changing the pin characteristics or strap dimensions, making the system versatile and cost-effective across different applications.
3Adaptability or versatility
If the EA strap is designed to be flexible to meet a wide range of load levels and profiles, then adaptability is improved, but the design complexity increases
Solution Approach 1:
The patent achieves flexibility in meeting a wide range of load levels and profiles through systematic parameter changes in a relatively simple strap-pin structure. By varying a limited set of parameters (pin diameter, material, strap thickness, curvature radius), the system can accommodate diverse requirements without becoming structurally complex.
Solution Approach 2:
The EA strap incorporates dynamic geometric features such as curved portions and varying thickness regions that allow the structure to adapt its mechanical response. These dynamic geometric variations enable the strap to achieve different load profiles while maintaining a relatively simple overall design that does not require multiple discrete components.
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 provides improved control over breakaway load levels and profiles, simplifies adjustments, enhances stability against impact loading, and allows for a higher initial load before unrolling, while maintaining dimensional control and reducing assembly complexity.
Implementation Method 1
a pin extending through the radially inner segment of the stationary leg and the moveable leg
Implementation Method 2
a pin extending through the radially inner segment of the stationary leg and the moveable leg
Implementation Method 3
an energy absorption strap assembly operatively coupled to an upper jacket and configured to unroll once a specified collapse load is exceeded
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, the moveable leg extending from a first strap end region to a curved portion, the stationary leg extending from the curved portion to a second strap end region, wherein the second strap end region forms a U-shape defined by a radially outer segment, a radially inner segment and a connecting segment to join the radially outer segment and the radially inner segment. The energy absorbing strap assembly also includes a pin extending through the radially inner segment of the stationary leg and the moveable leg.