Vehicle Subframe Composite Joint Detachment Mechanism
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Solution Overview
Problem
Existing vehicle subframe and floor attachment systems require high force to detach during impacts, leading to potential damage and varying detachment forces across different vehicle sizes, and do not effectively prevent toeboard intrusion.
Innovation Solution
A vehicle subframe with a composite end joint featuring a collar and tapered notch configuration that interacts with a bolt to break and detach from the floor upon impact, allowing controlled and predictable separation while maintaining rigidity during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid attachment with bolts is used to secure the subframe to the floor, then the attachment strength and rigidity are improved, but the force required to detach during impact increases and may cause damage to the floor or subframe
Solution Approach 1:
The end joint is segmented into a collar and a tapered notch that can separate from each other during impact. The collar remains attached to the subframe while the notch detaches, allowing controlled separation that reduces the force required for detachment compared to a fully rigid bolted connection.
Solution Approach 2:
The attachment system transitions from a rigid state during normal operation to a detached state during impact. The tapered notch geometry enables this parameter change by allowing the joint to remain rigid under normal loads but facilitate controlled detachment when subjected to impact forces, thereby reducing the detachment force requirement.
2Stability of the object's composition
If the subframe is rigidly attached to the floor, then structural integrity during normal operation is improved, but toeboard intrusion prevention during impact is worsened
Solution Approach 1:
The attachment system transitions from a static rigid connection to a dynamic detached state during impact. The collar-notch mechanism allows the joint to maintain structural integrity during normal operation but enables controlled detachment during impact to prevent toeboard intrusion, thus resolving the contradiction between stability and harm prevention.
3Strength
If slot configurations are used to provide partial detachment, then deformation prevention is improved, but the detachment force varies between vehicles
Solution Approach 1:
The detachment mechanism is localized to specific geometric features (collar and tapered notch) within the end joint, rather than relying on variable slot configurations. This local quality approach ensures consistent detachment behavior across different vehicle sizes by concentrating the detachment function in a controlled geometric relationship that is less sensitive to overall vehicle dimensions.
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 solution enables controlled and predictable detachment of the subframe from the floor during impacts, reducing toeboard intrusion and maintaining structural integrity, with optimized energy absorption and reduced deformation.
Implementation Method 1
The notch is configured to slidably receive the bolt in response to relative movement between the subframe and floor
Implementation Method 2
In the event of an impact, the floor and subframe interact to sheer the bolt. Shearing the bolt provides detachment between the floor and the subframe
Data Source
AI summary
A subframe for a vehicle includes a subframe structure and a rear end joint. The rear end joint is formed on the subframe structure for attachment to a floor via a bolt. The rear end joint defines a notch, having a collar surrounding the bolt. The rear end joint is configured such that, upon impact, the rear end joint interacts with the bolt to break the collar, split the notch, and detach the subframe structure from the floor.