Offset Exhaust Pipe Branching for Collision Stress Reduction
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Solution Overview
Problem
In vehicles with dual muffler exhaust systems, rear end offset collisions cause high loads that damage the mufflers and upstream components like primary silencers and secondary catalysts due to excessive bending stresses and pushing forces.
Innovation Solution
The exhaust pipe structure features offset branch pipes, a linear upstream section, and an oblique section that allows for angular displacement, reducing bending stresses and pushing forces by distributing shock loads and allowing rotational and horizontal displacement, thereby minimizing damage to the branching parts and upstream components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the exhaust pipe is arranged symmetrically with respect to the vehicle center, then the layout is simple and easy to manufacture, but the branch part and upstream components are highly susceptible to damage during rear end offset collisions due to concentrated bending stresses
Solution Approach 1:
The patent applies asymmetry by offsetting the branch part from the vehicle center toward one side. This asymmetric arrangement allows the exhaust pipe to better absorb collision forces from rear end offset collisions, reducing bending stresses on the branch part and upstream components while maintaining manufacturability through a modified but still straightforward layout configuration
2Strength
If the muffler is positioned on the collision side during rear end offset collision, then the exhaust system can handle the collision load, but high bending stresses are concentrated on the branch part causing damage
Solution Approach 1:
The patent introduces angular displacement capability as an additional degree of freedom for the exhaust pipe. By allowing the pipe to displace angularly during collision, the system distributes the collision load across multiple dimensions rather than concentrating bending stresses on the branch part, thereby maintaining strength while reducing stress concentration
3Reliability
If the exhaust pipe is rigidly fixed to prevent displacement, then upstream components are protected from pushing forces, but the branch part suffers from concentrated bending stresses during collision
Solution Approach 1:
The patent applies dynamics by allowing controlled angular displacement of the exhaust pipe during collision events. This dynamic response enables the system to protect upstream components from pushing forces while distributing bending stresses through the angular movement, preventing stress concentration on the branch part
4Reliability
If the branch pipes are made longer to reduce bending stress, then the branch part is protected from damage, but the exhaust pipe length increases and complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the exhaust pipe configuration, specifically the offset distance and angular displacement capability, to optimize the balance between branch part protection and system complexity. By carefully selecting these parameters, the system achieves damage resistance without excessive pipe length or complexity
Data Source
AI summary
A vehicle (1) is provided with an exhaust pipe (2) extending from an engine mounted in the front part of the vehicle to a branch part (24) in the rear part of the vehicle, and right and left branch pipes (25, 26) extending from the branch part to mufflers (5, 6) on both right and left sides. The branch part (24) is arranged so as to be offset to the side of either one muffler (5) of the right and left mufflers with respect to the center in the vehicle width direction; the exhaust pipe has an upstream part (2, 21) laid linearly to a bend part (22) positioned in the center in the vehicle width direction near the rear end of a fuel tank, and an oblique part (23) laid slantwise from the bend part toward the branch part; and the length of the branch pipe (25) having a longer distance to the muffler is approximately equal to the length of the oblique part (23).