Vehicle Exhaust Resistive Patch for Noise Damping
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Solution Overview
Problem
Existing vehicle exhaust systems face challenges in effectively reducing noise through additional components, which increase weight and cost, and microperforated materials are not structurally sound due to large holes required for noise attenuation, also affected by grazing flow.
Innovation Solution
A vehicle exhaust system with a pipe having a single or dual holes covered by a resistive material, such as microperforated sheets or powdered metal, with an open cavity to enhance structural integrity and acoustic damping, and an actuator to vary damping based on operating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional components such as mufflers and resonators are incorporated into the exhaust system, then noise attenuation is improved, but weight and cost increase
Solution Approach 1:
The patent combines the noise attenuation function directly into the exhaust pipe wall by forming holes within the pipe itself and covering them with microperforated material, rather than adding separate mufflers or resonators. This integration eliminates the need for additional components while maintaining noise reduction functionality.
Solution Approach 2:
The patent uses microperforated material with numerous small holes (typically 0.1-2.0 mm in diameter) to provide acoustic damping. The porous structure allows sound waves to enter the holes and dissipate energy through friction and viscous effects, achieving noise attenuation without requiring large bulky components.
2Object-affected harmful factors
If large holes are formed in the pipe and covered with microperforated material, then noise attenuation is improved, but structural integrity deteriorates
Solution Approach 1:
The patent applies microperforated material only at specific locations where noise attenuation is needed, rather than perforating the entire pipe. The small hole size (0.1-2.0 mm) is carefully selected to provide acoustic damping while minimizing impact on overall structural strength. The microperforated material is bonded to the pipe surface to maintain local rigidity.
Solution Approach 2:
The patent optimizes the hole diameter parameter to a specific range (0.1-2.0 mm) that balances acoustic performance with structural integrity. This parameter optimization allows the pipe to maintain sufficient strength while achieving effective noise attenuation through the microperforated structure.
3Object-affected harmful factors
If microperforated material is used to dampen noise, then acoustic damping is improved, but durability deteriorates due to grazing flow effects
Solution Approach 1:
The patent addresses grazing flow effects by creating a three-dimensional cavity structure behind the microperforated material, rather than using a simple flat surface. The cavity depth and geometry are designed to redirect exhaust flow away from the microperforated material surface, reducing direct impingement and grazing flow damage while maintaining acoustic damping effectiveness.
Solution Approach 2:
The patent introduces a cavity structure as an intermediary between the exhaust flow and the microperforated material. This cavity acts as a buffer zone that modifies the flow pattern, reducing the direct harmful effects of high-velocity exhaust gases on the delicate microperforated material while allowing acoustic waves to still reach the damping surface.
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 configuration significantly reduces the required hole area by up to 95%, improving structural integrity and minimizing grazing flow effects while optimizing noise damping across various operating conditions.
Implementation Method 1
A member formed from a resistive material is overlapped over the at least one hole
Implementation Method 2
The at least one hole comprises the only hole in the pipe that extends entirely through the wall or only two holes, a first hole and a second hole, the first and second holes extending entirely through the wall, and with each of the two holes being covered by one member formed of the resistive material
Data Source
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AI summary
A vehicle exhaust system includes an exhaust component having an outer surface and an inner surface that defines an internal exhaust component cavity. At least one hole is formed in the exhaust component to extend through a wall of the exhaust component from the outer surface to the inner surface. A member is formed from a resistive material and is configured to overlap the at least one hole. At least one spacer is configured to space the member away from the inner or outer surface of the exhaust component to create an open cavity between the member and the exhaust component. In one example, an actuator is configured to cover and uncover the member dependent upon an operating characteristic to vary damping.