Rear Side Member Folding for Fuel Tank Protection
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Solution Overview
Problem
Existing tank-carrying vehicle rear body structures face limitations in absorbing collision energy due to the limited folding range of rear side members, leading to increased weight and cost when reinforcing other vehicle frame portions to protect the fuel tank.
Innovation Solution
A tank-carrying vehicle rear body structure design that incorporates a tank frame supported by rear side members, with a member-folding-facilitating part that aids in folding the rear side members to absorb energy, eliminating the need for additional reinforcement members by utilizing a torsion beam type suspension and tank frames with higher strength than the vehicle body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the folding range of rear side members is limited, then the structure is simpler, but the energy absorption capability is insufficient
Solution Approach 1:
The rear side member is divided into multiple sections with different functional characteristics: a first section with high rigidity for structural support, a second section with reduced rigidity for energy absorption through folding, and a third section with high rigidity for structural support. This segmentation allows each part to perform its specific function optimally, achieving both energy absorption and structural simplicity.
Solution Approach 2:
Different sections of the rear side member have different rigidity characteristics tailored to their specific functions. The first and third sections have high rigidity to maintain structural integrity, while the second section has reduced rigidity to facilitate folding and absorb energy during rear-end collisions. This local differentiation of properties resolves the contradiction between structural simplicity and energy absorption capability.
2Reliability
If reinforcement members are added to protect the fuel tank, then the protection capability is improved, but the vehicle weight and cost increase
Solution Approach 1:
The rear side member serves multiple functions: it provides structural support through its high-rigidity first and third sections, absorbs collision energy through folding in the second section, and protects the fuel tank by deforming in a controlled manner. This multi-functionality eliminates the need for separate reinforcement members, reducing vehicle weight and cost while maintaining protection capability.
Solution Approach 2:
The rear side member's own structure is designed to protect the fuel tank through its controlled folding behavior in the second section during rear-end collisions. The member serves itself as both the collision energy absorber and the protective element, eliminating the need for additional reinforcement members and thereby reducing vehicle weight and cost.
3Strength
If the rear side members are made with high rigidity throughout, then the structural strength is improved, but the folding capability and energy absorption are reduced
Solution Approach 1:
The rear side member is segmented into three sections with different rigidity characteristics. The first and third sections maintain high rigidity for structural strength, while the second section has reduced rigidity to enable folding and energy absorption. This segmentation resolves the contradiction by allowing different parts to have different mechanical properties suited to their functions.
Solution Approach 2:
The rigidity property is locally differentiated along the rear side member: high rigidity in the first and third sections for structural support, and reduced rigidity in the second section for controlled folding. This local quality variation allows the member to simultaneously achieve structural strength and energy absorption capability.
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 enhances energy absorption in the rear vehicle portion, reducing the need for reinforcement members and thus lowering vehicle weight and cost while effectively protecting the gas tank from collision damage.
Implementation Method 1
When an input load toward the front side of the vehicle is applied to the rear body structure such that the rear side members are folded such that the upper portion of the rear body structure becomes convex, the member-folding-facilitating part aids the folding. As a result, the rear side members are folded significantly, and the amount of crushing of the rear portion of the vehicle can be increased. The amount of energy of the input load absorbed by the entire rear portion of the vehicle is increased
Data Source
AI summary
A gas tank is protected by absorbing collision energy with the rear of a vehicle. Rear-side tank frame supports the tank at a position below a rear side member. The front portion of the tank frame is secured on rear side member, while the rear portion is directly or indirectly secured thereto. A torsion beam is arranged ahead of the tank frame. When an input load is exerted at rear end portions of the rear side member and tank frame toward the front of the vehicle, rear side member is folded to a V shape, upward with respect to the vehicle body. The tank frame collides with the torsion beam, and the front portion of the tank frame is pushed upward along with rear side member.