Steering Column Energy Absorption with Controlled Arrest Release
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Solution Overview
Problem
Existing energy absorption devices in steering columns for vehicles often result in undesirable force peaks during crashes, leading to high accelerations and potential injury to the vehicle driver due to the shearing of arresting elements.
Innovation Solution
An energy absorption device with a movable arresting element that transitions from a blocking position to a release position during a crash, allowing relative movement between the inner and outer casing tubes, thereby absorbing energy without activating the arresting element, and utilizing a pyroelectric propellant charge or magnetic actuator for quick movement into the release position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shear bolt is used as an arresting element to block relative movement in normal operation, then the steering column maintains structural integrity during normal use, but in a crash situation the shear bolt shears off causing a force peak that exposes the driver to high accelerations
Solution Approach 1:
The arresting element is divided into a first portion and a second portion connected by a fracture element. The fracture element is designed to fracture at a controlled location, separating the arresting element into two portions that move apart, thereby avoiding the force peak caused by sudden shearing of a solid bolt while maintaining the blocking function during normal operation
Solution Approach 2:
The fracture element acts as an intermediary component between the first and second portions of the arresting element. It provides a controlled failure mechanism that mediates the transition from blocked to unlocked state, replacing the direct shearing action of a traditional shear bolt with a controlled fracture that occurs at a predetermined location with reduced force transmission to the driver
2Reliability
If the arresting element is designed to prevent relative movement during normal operation, then misuse of the energy absorption element is avoided, but the energy absorption element cannot be activated when needed in a crash
Solution Approach 1:
The arresting element transitions from a static blocked state during normal operation to a dynamic unlocked state during crash. The fracture element is designed to remain intact under normal axial loads but fracture under high crash forces, enabling the system to adapt its behavior based on the severity of the situation
Solution Approach 2:
The fracture element is designed with specific material and geometric parameters that allow it to withstand normal operating loads but fail under crash conditions. By controlling the fracture location and characteristics, the system changes its mechanical parameters from a blocked configuration to an unlocked configuration that allows 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
This solution reduces the loading on the vehicle driver by ensuring energy absorption occurs solely through the energy absorption element, minimizing force peaks and enhancing safety by allowing quick and controlled energy absorption during crashes.
Implementation Method 1
utilizing a pyroelectric propellant charge or magnetic actuator for quick movement into the release position
Implementation Method 2
utilizing a pyroelectric propellant charge or magnetic actuator for quick movement into the release position
Implementation Method 3
the first energy absorption element, for example by dissipation, if for example the outer casing unit and the inner casing tube in the steering column move toward one another in the crash situation
Data Source
AI summary
An energy absorption device for a steering column for a motor vehicle includes an energy absorption element for absorbing energy by a relative movement between at least two components of the steering column in a crash situation, and at least one arresting element for arranging in a blocking position for blocking the relative movement.