Steering Column Deformable Tab for Crash Energy Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering column assemblies face challenges in incorporating a crash energy system that provides consistent force-vs-stroke profiles regardless of the initial reach-adjustment position, particularly in designs where the upper shroud slides inside the lower shroud, and struggle to incorporate tunable and adaptive energy absorption features such as Energy Absorption Straps (EAS) and varying energy absorption levels for different driver conditions and vehicle impacts.
Innovation Solution
A collapsible steering column assembly design featuring a deformable tab that secures the clamp rail to the upper shroud, allowing axial movement during crashes, and an energy absorbing mechanism with adjustable straps that can change energy absorption levels based on driver conditions and vehicle speed, using a pyrotechnic device to select the appropriate mode of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the upper shroud portion slides inside the lower shroud portion, then the steering shaft can be supported by bearings towards each end of the upper shroud resulting in good stiffness, but it becomes more difficult to incorporate a crash energy system that provides consistent force-vs-stroke profile regardless of initial reach-adjustment position
Solution Approach 1:
The patent introduces a deformable tab as an intermediary element between the upper and lower shroud portions. This tab acts as a mediator that controls the interaction between the two shroud portions during collapse, ensuring consistent energy absorption regardless of the initial reach-adjustment position. The tab deforms in a controlled manner to provide predictable crash characteristics while allowing the bearing-supported steering shaft to maintain its stiffness.
2Ease of operation
If the upper shroud portion slides inside the lower shroud portion, then reach adjustment is enabled, but it becomes more difficult to incorporate tunable and adaptive energy absorption features such as Energy Absorption Straps
Solution Approach 1:
The patent segments the energy absorption function into distinct components: the deformable tab for primary energy absorption and Energy Absorption Straps for additional tunable energy absorption. This segmentation allows each component to perform its specific function independently, making the overall system more manageable and adaptable. The tab handles basic collapse while the straps provide adjustable energy absorption levels for different crash scenarios.
Solution Approach 2:
The patent implements dynamic energy absorption capabilities through the deformable tab that changes its mechanical properties during collapse. The tab transitions from a rigid state during normal operation to a deformable state during crash, providing adaptive energy absorption. This dynamic behavior allows the system to adjust energy absorption characteristics based on the crash conditions without requiring complex active control systems.
3Duration of action of moving object
If the upper shroud portion slides inside the lower shroud portion, then telescopic collapse is achieved, but friction effects between inner and outer tubes reduce predictability of overall energy absorption
Solution Approach 1:
The deformable tab serves as an intermediary that mediates the interaction between the inner and outer tubes during telescopic collapse. By controlling the deformation of the tab, the patent reduces the friction effects between the tubes and makes the energy absorption more predictable. The tab acts as a buffer that absorbs energy in a controlled manner, reducing the variability caused by friction.
4Stability of the object's composition
If a clamp mechanism is used to secure the shroud portions, then free play between shroud portions is removed, but squeezing forces create friction that reduces energy absorption consistency
Solution Approach 1:
The patent applies dynamic clamping forces through the clamp mechanism that adjust during collapse. The clamp provides sufficient force to eliminate free play during normal operation but allows the force to reduce as collapse progresses. This dynamic adjustment maintains stability when needed while reducing friction-induced variability during energy absorption, achieving both free play elimination and consistent energy absorption.
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 design ensures consistent crash performance by controlling the collapse force and energy absorption levels, reducing variability and improving the column's ability to absorb energy effectively across different scenarios, including varying driver conditions and impact angles.
Implementation Method 1
the tab is deformable under a predefined load applied to the upper shroud so as to unhook from the rail allowing the upper shroud to move axially
Implementation Method 2
an energy absorbing mechanism with adjustable straps that can change energy absorption levels based on driver conditions and vehicle impact speeds
Implementation Method 3
using a pyrotechnic device to select the appropriate mode of operation
Data Source
AI summary
A collapsible steering column assembly comprising a steering shaft that is supported within a steering column shroud, the shroud comprising an upper shroud portion and a lower shroud portion, in which the upper shroud portion is located towards the end of the steering shaft that is nearest the steering wheel and the lower portion is located towards the end of the shaft furthest from the steering wheel, the upper portion being at least partially received within the lower portion so that the upper portion can telescopically collapse into the lower portion during a crash, a support bracket that in use is secured to a fixed part of the vehicle and includes two support bracket arms that depend from a base portion to embrace the shroud, a clamp rail that is releasably secured to the upper shroud portion, the clamp rail including a slot that extends generally horizontally, and a clamp pin that extends through an opening in each of the arms of the bracket and through the generally horizontal slot in the rail, the clamp pin carrying a clamp mechanism that is movable between an unclamped position in which the rail can move freely relative to the clamp pin and a clamped position in which the rail is fixed relative to the clamp pin. The rail is secured to the upper shroud portion by a deformable tab which protrudes from the upper shroud portion to hook onto a part of the rail that faces the steering wheel end of the shroud. In use of the assembly with the cam mechanism in the clamped condition the tab is deformable under a predefined load applied to the upper shroud so as to unhook from the rail allowing the upper shroud to move axially relative to the rail and hence relative to the clam pin to permit collapse of the steering column shroud.