Fuel Cell Stack Frame Impact Absorption
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Solution Overview
Problem
Fuel tanks in fuel cell vehicles are prone to damage during collisions due to potential contact with the stack frame, leading to breakage and safety concerns.
Innovation Solution
The fuel tank is positioned behind the stack frame, with a configuration where the right and left members of the stack frame absorb impact forces, allowing them to separate from the central member and move with the fuel tank, reducing the likelihood of damage. This configuration includes a crash box and specific joining portions with varying mechanical strengths to facilitate deformation and absorption of impact energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel tank is placed below the vehicle cabin to extend cruising range, then the fuel tank may collide with the stack frame during front-end collision, but placing the fuel tank behind the stack frame prevents direct corner collision damage
Solution Approach 1:
The stack frame is divided into multiple members (central member, right member, left member, front cross member) with distinct functions. The right and left members are designed as separate impact-absorbing elements that can deform independently, while the central member provides structural support. This segmentation allows the frame to absorb impact energy through controlled deformation of specific members rather than transmitting force directly to the fuel tank.
Solution Approach 2:
The right and left members of the stack frame serve as intermediary elements between the central member and the fuel tank. During collision, these intermediate members deform and absorb impact energy, preventing direct contact between the central member and the fuel tank. The front cross member also acts as an intermediary structure that connects the right and left members, facilitating energy distribution and absorption.
2Loss of energy
If the joining portions are designed with overlapping configurations, then the stack frame can absorb impact energy through member separation, but the manufacturing complexity increases
Solution Approach 1:
The joining portions are pre-designed with specific overlapping configurations and mechanical strength differentials before assembly. The rear-end portions are intentionally designed with lower mechanical strength to serve as predetermined breaking points, while the front-end portions have higher strength to maintain structural integrity. This preliminary design allows the frame to automatically absorb impact energy through controlled separation at the rear joining portions without requiring active control systems during collision.
Solution Approach 2:
Different portions of the joining connections have different mechanical strengths tailored to their specific functions. The rear-end portions of the joining portions between the central member and right/left members are designed with lower mechanical strength to facilitate separation and energy absorption. In contrast, the front-end portions and the joining portion of the front cross member have higher mechanical strength to maintain overall frame integrity. This localized variation in material properties enables selective deformation during impact.
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 design effectively minimizes fuel tank damage during collisions by allowing the stack frame members to absorb and redirect forces, thereby protecting the fuel tank from direct impact and corner collisions.
Implementation Method 1
When the fuel cell vehicle receives an impact and the fuel tank collides with the stack frame, the right member and the left member hit the fuel tank first, so that the rear side of the left member and the rear side of the right member receive respective forces in respective directions to be separated from the central member
Implementation Method 2
the left member and the right member are separated from the central member and move to follow the movement of the fuel tank
Implementation Method 3
A rear-end portion of the first joining portion between the central member and the right member and a rear-end portion of the second joining portion between the central member and the left member serve as starting points of breaking, and the left member and the right member are separated from the central member
Data Source
AI summary
A fuel cell vehicle includes: a stack frame providing a fuel cell stack, the stack frame being placed in front of a vehicle cabin; and a fuel tank placed behind the stack frame. The stack frame includes a central member, a right member joined to the central member, a left member joined to the central member, and a front cross member. The front cross member is joined to front edge portions of the central member, the right member, and the left member. A front-end portion of a first joining portion between the central member and the right member and a front-end portion of a second joining portion between the central member and the left member overlap with a third joining portion of the front cross member with the front edge portions of the central member, the right member, and the left member.