Steering Column Elastic Prestress Breakaway Peak Reduction
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Solution Overview
Problem
Existing steering columns experience a high force peak, known as the breakaway peak, when the breakaway connection opens during a crash, which can lead to increased risk of injury and instability, and current designs often require complex and costly energy absorption mechanisms.
Innovation Solution
The steering column incorporates an elastic prestress in the bending wire or strip, which biases the casing unit relative to the retaining part, reducing the force required to open the breakaway connection and distributing the force more evenly, thereby reducing or eliminating the breakaway peak, while maintaining stability during normal driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a breakaway connection is used to allow casing unit displacement during crash, then energy absorption capability is improved, but a high force peak (breakaway peak) occurs when the connection opens
Solution Approach 1:
The bending wire or strip is pre-deformed during assembly to store elastic energy and create a prestress force. This preliminary action ensures that when the breakaway connection opens during a crash, the prestress force gradually reduces the impact force peak, rather than allowing a sudden force spike to occur.
Solution Approach 2:
The elastic prestress in the bending wire or strip acts as a cushioning mechanism that is already in place before the crash occurs. This prestress creates a force that opposes the sudden opening of the breakaway connection, thereby cushioning the impact and reducing the breakaway peak force.
2Force
If the bending wire or strip is pre-deformed to create elastic prestress, then the breakaway peak force is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The pre-deformation of the bending wire or strip is performed during the assembly process rather than requiring a separate manufacturing step. This preliminary action integrates the prestress creation into the existing assembly workflow, minimizing additional manufacturing complexity while achieving the force reduction benefit.
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 effectively reduces the breakaway peak force, enhances safety by distributing crash forces more evenly, and simplifies the energy absorption mechanism, providing a stable connection during normal operation and efficient energy absorption during crashes.
Implementation Method 1
an energy absorption connection which comprises at least one bending wire or strip, which is parallel to the longitudinal axis in the direction of the vehicle front displacement of the casing unit relative to the retaining part
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a steering column for a motor vehicle, comprising a casing unit (2), which rotatably supports a steering shaft about the longitudinal axis thereof, and a retaining part (5). The casing unit (2) is held in a fixed manner relative to said retaining part up to a threshold value of a force acting on the casing unit (2) in a parallel manner to the longitudinal axis of the steering shaft in the direction of the front of the vehicle, and when the threshold value is exceeded, the casing unit is movably held in a parallel manner to the longitudinal axis in the direction of the front of the vehicle. According to the invention, the casing unit (2) is connected to the retaining part (5) via an energy-absorbing connection, which comprises at least one bending wire or strip (32) that is deformed when the casing unit (2) is moved relative to the retaining part (5) in a parallel manner to the longitudinal axis in the direction of the front of the vehicle, and via a breakaway connection, which is closed up to a threshold value of the force and blocks a movement of the casing unit (2) relative to the retaining part (5) and which opens when the threshold value of the force is exceeded. If the breakaway connection is closed, the bending wire or strip (32) is elastically deformed between the casing unit (2) and the retaining part (5), and said bending wire or strip preloads the casing unit (2) relative to the retaining part (5) with respect to a movement parallel to the longitudinal axis of the steering column in the direction of the front of the vehicle.