Vehicle Subframe Weak Portions for Collision Load Management
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Solution Overview
Problem
The existing subframe structure below a power plant room in vehicles is prone to deformation during frontal collisions, leading to potential contact between rear members and the vehicle compartment, causing damage due to its weak points and lack of rigidity.
Innovation Solution
A subframe structure with a pair of extension members featuring first and second weak portions, where the first weak portion is deformable downward and the second weak portion is deformable upward, preventing the rear member from bending upward and thus avoiding contact with the vehicle compartment, utilizing a design with distinct height dimensions and reinforcement to manage collision loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the subframe structure has weak portions that are deformable, then collision load absorption is improved, but the rear member may be bent upward causing members to contact the vehicle compartment
Solution Approach 1:
The extension member is divided into multiple weak portions (first and second weak portions) with different deformation characteristics. The first weak portion deforms downward while the second weak portion deforms upward, segmenting the deformation behavior to control the overall structural response and prevent harmful rear member bending.
Solution Approach 2:
Different portions of the extension member are given different local properties: the first weak portion is designed to be deformable downward, while the second weak portion is designed to be deformable upward. This local differentiation allows controlled deformation patterns that absorb energy while preventing harmful effects.
2Loss of energy
If the lower member has low rigidity and strength to allow bending, then collision load absorption is improved, but the front suspension member cannot be secured from falling off
Solution Approach 1:
The structure is segmented into weak portions for energy absorption and stronger connecting parts for securing functions. The connecting parts maintain sufficient strength to prevent suspension member detachment, while the weak portions between them provide controlled deformation for energy absorption.
Solution Approach 2:
Different local regions have different mechanical properties: the weak portions have low rigidity for deformation and energy absorption, while the connecting parts have high strength for securing the suspension member. This local quality differentiation resolves the contradiction between strength and energy absorption.
3Device complexity
If the subframe is designed with a single bending point, then结构简单性 is improved, but the cross member may contact the ground causing upward bending and member contact with vehicle compartment
Solution Approach 1:
Instead of a single bending point, the structure uses multiple weak portions (first and second weak portions) with different deformation directions. This segmentation prevents the cross member from contacting the ground by distributing the deformation across multiple controlled points.
Solution Approach 2:
The second weak portion is designed to deform upward (opposite direction) when the first weak portion deforms downward. This inverted deformation behavior at different locations prevents the cross member from contacting the ground, solving the problem caused by single-direction bending.
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 subframe structure effectively absorbs collision loads by bending the extension members in a controlled manner, preventing rear member deformation and compartment damage, while ensuring the rear member falls off safely, thereby enhancing vehicle safety during frontal impacts.
Implementation Method 1
a first weak portion located forwardly of the corresponding connecting part and being deformable downward when a load is applied
Implementation Method 2
a second weak portion located forwardly of the first weak portion and being deformable upward when a load is applied
Data Source
AI summary
A subframe structure includes: a left-right pair of extension members extending in a vehicle front-rear direction and each having a rectangular orthogonal cross section; a rear member connected to rear end portions of the extension members and extending in a vehicle width direction; and connecting parts connecting the rear end portions and the rear member. Each extension member includes: a first weak portion located forwardly of the corresponding connecting part and deformable when a load is applied; and a second weak portion located forwardly of the first weak portion and deformable when a load is applied. The first and second weak portions of each extension member are formed in upper and lower faces thereof, respectively. The orthogonal cross section of each extension member has a height, dimension H1 at the first weak portion and a height dimension H2 at the second weak portion and H1 is smaller than H2.