Vehicle Backrest Cross Member for Rear-End Collision Energy Dissipation
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Solution Overview
Problem
Existing motor vehicle seat backrest fastening systems do not effectively dissipate crash energy during rear-end collisions, resulting in high loads on occupants and potential head contact with the rear window frame.
Innovation Solution
A cross member is interposed between the vehicle body and the seat backrest, configured with parallel front and rear boundary walls to dissipate energy through parallelogram-like twisting, reducing the backrest's angle change and deformation during a collision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the backrest is directly connected to the vehicle body via backrest bearing plates and center bearing, then the structure is simple and easy to manufacture, but the loads on occupants are high during rear-end collision due to insufficient energy dissipation
Solution Approach 1:
A cross member is introduced as an intermediary component between the vehicle body and the backrest mounting system. This cross member absorbs and dissipates crash energy during rear-end collisions through controlled deformation, preventing direct transmission of high forces to the backrest and occupants. The cross member acts as a buffer that mediates the force transfer path.
Solution Approach 2:
The cross member is designed with specific geometric parameters (length, cross-section, material properties) that enable it to undergo controlled plastic deformation during collision. By changing the structural parameters of the cross member, the energy absorption characteristics are optimized to reduce peak forces while maintaining normal operational rigidity.
2Stability of the object's composition
If the backrest is rigidly connected to the vehicle body, then the backrest stability is high during normal operation, but the backrest angle changes strongly during rear-end collision causing head contact with rear window frame
Solution Approach 1:
The connection system transitions from a purely rigid static structure to a dynamic system where the cross member can deform under load. During normal operation, the cross member maintains rigidity through its structural design, but during collision, it dynamically adapts by deforming to absorb energy, thereby reducing the backrest angle change and preventing harmful occupant movement.
Solution Approach 2:
The cross member is pre-configured with energy-absorbing characteristics through its design (geometry, material selection, mounting configuration) to provide cushioning effect before the actual collision occurs. This beforehand preparation ensures that when a rear-end collision happens, the cross member is already positioned and structured to dissipate energy effectively, reducing the backrest angle change.
3Object-affected harmful factors
If energy-dissipating cross member is interposed between vehicle body and backrest, then the crash energy is effectively dissipated and loads on occupants are reduced, but the device complexity increases
Solution Approach 1:
The cross member serves multiple functions simultaneously: it provides structural support for the backrest mounting system during normal operation, acts as an energy-absorbing element during rear-end collisions, and maintains geometric stability through its parallelogram configuration. By combining these functions in a single component, the overall device complexity is minimized while achieving the desired safety performance.
Solution Approach 2:
The mounting brackets are integrated with the cross member structure, combining the support function and the energy dissipation function into a unified assembly. This merging reduces the number of separate components and simplifies the overall device complexity while maintaining the effectiveness of the energy dissipation mechanism.
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 configuration significantly reduces the backrest's angle change and deformation, minimizing loads on occupants and preventing head contact with the rear window frame by effectively dissipating crash energy.
Implementation Method 1
the cross member is interposed between the body of the motor vehicle and the seat of the backrest in such a way that a considerable part of the crash energy can be dissipated. This reduces the angle by which the backrest moves against the direction of travel in the event of a rear-end collision
Implementation Method 2
essentially over its entire extent in the transverse direction of the vehicle, and thus in a correspondingly high energy dissipation in the cross member
Data Source
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AI summary
The backrests (11, 12) of a rear seat system (10) are attached to a cross member (20) which extends between the wheel housings of the rear structure (14) of a motor vehicle. This indirect attachment of the backrests (11, 12) instead of the direct attachment on the rear structure (14) allows the intermediately connected cross member (20) to absorb a large part of the impact force which is introduced into the backrests (11, 12) in the case of a rear-end collision and to dissipate it through parallelogram-like deformation. As a result, the rearward displacement of the backrests (11, 12) is reduced, resulting in improved vehicle occupant protection.