Steering Column Energy Absorption With Tolerance-Independent Breakaway Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing energy absorption devices in steering columns are sensitive to dimensional and production tolerances, affecting the breakaway force required for energy absorption, which compromises the reproducibility and safety of the crash response.
Innovation Solution
Incorporation of breakaway protrusions that protrude from the side faces of the deformation strip, allowing for a defined breakaway force threshold independent of the retaining arrangement, ensuring secure fixing in the rest state and controlled energy absorption during a crash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retaining knobs are clamped frictionally against retaining protrusions to ensure secure fixing without play, then the retaining force is determined and secure fixing is achieved, but the breakaway force becomes sensitive to dimensional and production tolerances, impairing the reproducibility of energy absorption
Solution Approach 1:
The energy absorption device is segmented into two independent functional parts: a retaining arrangement (retaining knobs and retaining protrusions) for secure fixing, and a breakaway arrangement (deformation knobs and deformation portion) for controlled energy absorption. This segmentation allows each part to be optimized independently, so that manufacturing tolerances in the retaining arrangement do not affect the breakaway force reproducibility.
Solution Approach 2:
The breakaway function is extracted from the retaining arrangement by providing separate breakaway protrusions that are plastically deformable. This extraction creates an independent breakaway mechanism that is not sensitive to the dimensional tolerances of the retaining knobs and retaining protrusions, thereby ensuring reproducible breakaway force.
2Loss of energy
If the open passage between deformation knobs is narrower than the width of the deformation portion, then effective energy absorption through plastic deformation is achieved, but the deformation knobs cannot engage properly with the deformation strip in the rest state
Solution Approach 1:
The deformation portion is designed to be dynamically changeable in width: in the rest state, it has a larger width that allows easy engagement of the deformation knobs; during crash deformation, it plastically deforms to reduce width, enabling effective energy absorption through continuous plastic deformation of the side faces.
Solution Approach 2:
The geometric parameter (width) of the deformation portion is changed during operation. In the rest state, the width is sufficient for knob engagement; during crash, the width reduces through plastic deformation, transforming the geometric parameter to achieve the desired energy absorption characteristic.
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 provides a reproducible and defined breakaway force, enhancing safety by decoupling the fixing mechanism from the energy absorption process, thereby improving the control of deceleration and minimizing injury risk during a crash.
Implementation Method 1
an energy absorption element, attached between the actuator and the casing unit, of the energy absorption device is plastically deformed and absorbs the kinetic energy introduced in the longitudinal direction by converting it into deformation work
Data Source
AI summary
A steering column for a motor vehicle comprises an actuator in which a steering spindle is mounted so as to be rotatable about a longitudinal axis extending in a longitudinal direction, a casing unit in which the actuator is held so as to be displaceable in the longitudinal direction, and an energy absorption device incorporated between the casing unit and the actuator, the energy absorption device including a deformation strip that is elongate in the longitudinal direction and is fastened to the actuator or the casing unit, and a deformation slide that cooperates with said deformation strip, is attached to the casing unit or the actuator, engages around the deformation strip, and has in each case a pair of retaining knobs and deformation knobs that protrude towards side faces of the deformation strip, wherein the retaining knobs are held in the longitudinal direction against retaining protrusions of the deformation strip, wherein the deformation knobs are arranged at a distance from the retaining knobs in the longitudinal direction and are at a transverse distance from one another which is less than the width of the deformation strip between the mutually opposite side faces extending in the longitudinal direction, and wherein breakaway protrusions that protrude from the side faces are formed in the longitudinal direction in front of the deformation knobs.