Vehicle Lower Structure Guard with Dynamic Bolt Constraint
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Solution Overview
Problem
In vehicle lower portion structures, the installation of brace members between cross members can hinder the deformation of side members during frontal collisions, leading to a decrease in the absorption of collision energy.
Innovation Solution
The vehicle lower portion structure incorporates a guard member with a brace member suspended between cross members, featuring an elongated insertion hole with a passable portion and a tied-up section, allowing the bolt to move relative to the brace member during frontal collisions while limiting movement during asymmetrical collisions, thus preventing a decrease in collision energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a brace member is suspended between cross members to enhance guard member strength, then the strength and protective capability of the guard member is improved, but the deformation of side members during frontal collision is hindered, leading to decreased collision energy absorption
Solution Approach 1:
The insertion hole is designed as an elongated hole extending in the vehicle width direction, allowing the bolt to move dynamically from an initial position to a collision position during frontal impact. This dynamic movement enables the brace member to disengage from restraining the side members, allowing them to deform and absorb collision energy while maintaining structural strength during normal operation
Solution Approach 2:
The geometric parameters of the insertion hole (elongated shape, specific extension direction, and position) are optimized to enable controlled bolt movement. The hole's dimensions and orientation are specifically designed to permit lateral displacement of the bolt during collision, changing the constraint state from rigid to flexible, thereby resolving the contradiction between strength and energy absorption
2Stability of the object's composition
If the brace member is rigidly fastened to cross members to prevent deformation, then structural stability is improved, but the side members cannot deform during collision, reducing energy absorption capability
Solution Approach 1:
The fastening system transitions from a static rigid connection to a dynamic connection that adapts during collision. The bolt's ability to move within the elongated insertion hole transforms the structural behavior, allowing the system to maintain stability during normal use while enabling controlled deformation during impact events
3Reliability
If the brace member is installed between cross members to protect on-board components, then component protection is improved, but the side members' deformation capability during frontal collision is restricted
Solution Approach 1:
The dynamic bolt movement mechanism within the elongated insertion hole allows the system to provide component protection through the brace member's presence while simultaneously enabling side member deformation for energy absorption during collision. The bolt's positional change from initial to collision position facilitates this dual functionality
Data Source
AI summary
In a vehicle lower portion structure, a plurality of cross members are suspended along a vehicle width direction between a pair of side rails. Further, an oil pan guard is suspended along a longitudinal direction between a No. 2 cross member and a No. 3 cross member to protect an oil pan of a transmission from below. When a vehicle collides on its front, engagement between the oil pan guard and the cross member is released, to thereby prevent a decrease in the amount of collision energy to be absorbed by the pair of side rails.