Spherical Joint Placement for Exhaust Vibration Damping
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Solution Overview
Problem
Conventional exhaust systems with spherical joints fail to damp vibrations effectively when the applied bending moment is less than the torque required to generate maximum static friction, leading to inefficient vibration reduction from the engine to the automobile body.
Innovation Solution
Determining and placing spherical joints at positions within the exhaust system where the applied vibration generates a bending moment equal to or greater than the torque required for maximum static friction, using strain gauges or CAE analysis to simulate engine vibration and identify optimal positions for maximum friction generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical joints are placed in conventional exhaust systems to connect exhaust pipes, then the structure can transmit vibration from engine to automobile body, but the vibration damping effect is insufficient when bending moment is less than the torque required for maximum static friction
Solution Approach 1:
The patent applies preliminary action by determining optimal spherical joint arrangement positions in advance through simulation before actual installation. The method simulates engine vibration to calculate bending moments at various positions, identifies positions where bending moment exceeds the torque required for maximum static friction, and determines spherical joint positions beforehand. This ensures that when the exhaust system is actually installed, the spherical joints are guaranteed to operate in the sliding regime for effective vibration damping, eliminating the need for trial-and-error installation.
2Ease of operation
If spherical joints are placed at positions where upstream and downstream move in synchronization, then installation is simplified, but bending moment is insufficient to generate maximum static friction for effective vibration damping
Solution Approach 1:
The patent replaces the trial-and-error mechanical installation approach with a computational mechanics-based determination method. Instead of relying on simplified installation rules that may not ensure proper vibration damping, the method uses computer simulations to calculate bending moments and determine optimal spherical joint positions. This substitution of mechanical trial-and-error with computational analysis ensures both proper installation ease and effective vibration damping performance simultaneously.
3Reliability
If spherical joints are added to increase vibration damping, then vibration transmission is reduced, but the system complexity and number of components increase
Solution Approach 1:
The patent applies local quality by determining that spherical joints should not be uniformly distributed throughout the exhaust system, but rather placed selectively at specific local positions where the bending moment exceeds the torque required for maximum static friction. The method calculates bending moments at various positions and identifies specific locations that meet the criterion, placing spherical joints only at these optimal positions. This localized approach ensures effective vibration damping while minimizing the total number of spherical joints required, avoiding unnecessary system complexity.
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
This approach enhances sliding between the spherical joint surfaces, effectively reducing vibration transmission from the engine to the automobile body by ensuring the spherical joints operate within their maximum static friction range.
Implementation Method 1
sliding between the spherical inner peripheral surface and the spherical outer peripheral surface contacting with each other occurs in the case of application of the bending moment larger than or equal to the torque such that the maximum static friction force is generated between the spherical inner peripheral surface and the spherical outer peripheral surface
Implementation Method 2
The friction accompanying this sliding dissipates vibration energy, to damp vibration transmitted from one of the member having the spherical inner peripheral surface and the member having the spherical outer peripheral surface to the other
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
Provided are a method for determining the disposition position of a spherical joint for coupling exhaust pipes to each other in an exhaust system, and an exhaust system, which enable engine vibrations to be more effectively damped. In the present invention, strain gauges are attached at a plurality of locations in an exhaust system (1), simulated vibrations which simulate engine vibrations are imparted to the upstream-side end of the exhaust system (1), and bending strain is measured at each strain gauge. On the basis of the bending strain measured at each strain gauge, detected is a position at which generated is a bending moment that is equal to or greater than or equal to a torque amount which generates a maximum static friction force between a spherical inner-circumferential surface (26) and a spherical outer-circumferential surface (27) of a spherical joint (2) which come into contact with each other, and the detected position is determined to be the disposition position for the spherical joint (2).