Vehicle Subframe Joint Structure for Crash Energy Absorption
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Solution Overview
Problem
Conventional subframe assemblies in vehicles are either brittle, leading to detachment during crashes, or have weak points that absorb minimal energy, resulting in increased noise and vibration, and often require additional connections that increase weight and complexity.
Innovation Solution
A subframe assembly with a strong, rigid connection between a crossmember, a straight arm, and a side bracket, where the side bracket is metallurgically bonded to the straight arm and both are bonded to an end bracket of the crossmember, using extruded aluminum for high-ductility and strength, allowing the assembly to deform without detaching and absorb energy during crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional casted subframe assemblies are used, then manufacturing is simpler, but the structure becomes brittle and detaches during crashes
Solution Approach 1:
The subframe assembly uses extruded aluminum members with high-ductility properties instead of brittle casted structures. The extruded aluminum straight arm and crossmember provide both manufacturing efficiency and superior crash performance through their ductile nature, preventing detachment while maintaining structural integrity.
Solution Approach 2:
The invention changes the material parameter from casted metal to extruded aluminum, fundamentally altering the mechanical properties from brittle to ductile. This parameter change enables the subframe to deform and absorb energy during crashes rather than detaching, while the extrusion process maintains manufacturing simplicity.
2Ease of manufacture
If the attachment bracket is positioned between the crossmember and straight arm, then connection is achieved, but the straight arm length is shortened and creates weak points
Solution Approach 1:
The side bracket is repositioned from an intermediate location between the crossmember and straight arm to the end of the straight arm. This spatial reconfiguration in another dimension allows the straight arm to maintain its full length and ductility while achieving secure connection through the side bracket's positioning at the arm's terminus.
3Strength
If the subframe assembly is strengthened by connecting to the vehicle body, then structural strength is improved, but noise and vibration increase
Solution Approach 1:
The invention uses curved or contoured connection surfaces and bracket designs that distribute loads more evenly, reducing stress concentrations that lead to vibration and noise. The smooth transitions and optimized geometries of the side bracket and end bracket minimize harmful vibrations while maintaining structural strength.
4Weight of moving object
If extruded aluminum is used for the subframe assembly, then weight is reduced, but connection strength may be compromised
Solution Approach 1:
The subframe assembly utilizes extruded aluminum members with optimized cross-sections and alloy compositions that maintain high strength-to-weight ratios. The extrusion process allows for integrated reinforcement features and optimized material distribution that preserve connection strength while minimizing weight.
Solution Approach 2:
The extruded aluminum members feature locally optimized geometries at connection points, with reinforced sections and tailored material properties where strength is critical. The side bracket and end bracket interfaces incorporate localized design features that maximize connection strength without compromising the overall lightweight construction.
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 assembly maintains structural integrity, absorbs significant energy during crashes, reduces noise and vibration, and prevents intrusion into the occupant compartment, while maintaining a lightweight design.
Implementation Method 1
The side bracket is metallurgically bonded to a side of the straight arm (at or close to an end of the straight arm), and both the side bracket and the straight arm are received into and metallurgically bonded to an end bracket of the crossmember
Data Source
AI summary
A subframe assembly for a vehicle, including: a straight arm; and a side bracket including a base coupled to an outboard side of the straight arm; wherein the outboard side of the straight arm defines a recess; and wherein an inboard side of the base of the side bracket includes a protrusion that nests conformally within the recess defined by the outboard side of the straight arm. Top and bottom edges of the outboard side of the straight arm, the recess, the inboard side of the base of the side bracket, and the protrusion are chamfered. The chamfered portions of the top and bottom edges of the outboard side of the straight arm, the recess, the inboard side of the base of the side bracket, and the protrusion are welded to join the side bracket to the outboard side of the straight arm.