Crash-Releasable Shaft Connection for Guided Energy Absorption
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Solution Overview
Problem
Longitudinal shaft assemblies in vehicles face challenges in crash scenarios where components can penetrate the passenger interior or fuel tank, leading to injury or fire risks, and existing designs struggle to absorb deformation energy effectively without compromising guiding functionality.
Innovation Solution
A shaft connection system that allows elongation and compression without sacrificing mutual guiding, featuring a first shaft with a hollow portion and a second shaft with a displacement portion, utilizing a form-fitting connection and an elastically deformable securing ring to maintain guiding during crashes, allowing controlled deformation and preventing deflection of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the longitudinal shaft assembly is designed as a rigid construction to prevent component penetration during crashes, then safety against injury and fire risks is improved, but the ability to absorb deformation energy effectively is worsened
Solution Approach 1:
The shaft connection transitions from a rigid fixed connection to a dynamic system that can adapt its state. The axial securing feature can be released under crash forces, allowing the shafts to move relative to each other and absorb energy through controlled deformation, while maintaining safety through guided movement paths.
Solution Approach 2:
The connection state between shafts changes from fixed to movable based on applied forces. The axial securing feature maintains the shafts in a fixed state during normal operation, but releases under crash conditions, changing the mechanical parameters of the system to enable energy absorption while preventing uncontrolled penetration.
2Strength
If the axial securing feature is released during crashes to allow elongation and compression, then deformation energy absorption is improved, but mutual guiding functionality is worsened
Solution Approach 1:
The shaft connection is segmented into multiple functional elements: the first shaft, second shaft, axial securing feature, and guide portion. This segmentation allows the axial securing feature to release for energy absorption while the guide portion maintains directional control, enabling independent optimization of each function.
Solution Approach 2:
The guide portion acts as an intermediary element between the shafts. Even when the axial securing feature releases and allows relative movement, the guide portion mediates this movement by constraining it to specific paths, thereby maintaining mutual guiding functionality while enabling energy absorption.
3Stability of the object's composition
If the guide portion is designed to maintain mutual guiding during elongation and compression, then guiding functionality is improved, but component deflection is worsened
Solution Approach 1:
The guide portion introduces a dimensional constraint to the shaft movement. By providing guide surfaces that constrain movement to specific paths, it adds a dimensional control mechanism that prevents deflection in unwanted directions while allowing controlled movement in the axial direction for energy absorption.
4Stability of the object's composition
If the form-fitting connection is designed to prevent deflection, then component stability is improved, but the ability to elongate and compress is worsened
Solution Approach 1:
The connection system dynamically switches between form-fitting connection (for stability) and axial movement (for elongation/compression). The axial securing feature maintains the form-fitting connection during normal operation, but releases under crash forces, allowing the shafts to elongate and compress while the guide portion prevents deflection.
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 shaft connection system ensures the longitudinal shaft assembly can elongate and compress without losing guiding functionality, absorbing crash energy while preventing component deflection, thus enhancing safety and maintaining the integrity of the assembly during vehicle crashes.
Implementation Method 1
an elastically deformable securing ring to maintain guiding during crashes
Data Source
AI summary
A shaft connection 1 for a longitudinal shaft assembly, has at least a first shaft having a first and second ends, and a second shaft, disposed so as to be coaxial with the first shaft, having first and second ends; the shafts extending axially. The first end forms a hollow portion. The first shaft end forms a first journal having a displacement portion. The first shaft end at least in an initial position of the shaft connection extends through the hollow portion which axially by the displacement portion forms a guide portion and circumferentially forms a form-fitting first connection. In the initial position a mutual axial displacement of the first and second shafts is prevented by an axial securing feature. In a crash the axial securing feature; is releasable by an axial release force. The first shaft is axially displaceable relative to the second shaft.