Pulsation Surface Component for Vehicle Exhaust Noise Attenuation
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Solution Overview
Problem
Existing vehicle exhaust systems face challenges in attenuating resonance frequencies without increasing weight or introducing new noise sources, as current methods like mufflers and resonators are costly and inefficient.
Innovation Solution
A vehicle exhaust system with a pulsation surface component that creates a reservoir to temporarily hold diverted exhaust gases, utilizing a minimum reservoir volume to inlet area ratio greater than or equal to 100 mm^3/mm^2 to prevent gas leakage and ensure efficient re-circulation, thereby minimizing noise and weight addition.
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 to attenuate resonance frequencies, then noise attenuation is improved, but the weight and cost of the exhaust system increase
Solution Approach 1:
The patent combines the noise attenuation function with the existing exhaust pipe structure by creating a pulsation reservoir that utilizes the pipe's own volume. The reservoir is formed by closing off a portion of the exhaust pipe, merging the structural component with the acoustic treatment function, thereby avoiding additional weight from separate mufflers or resonators
Solution Approach 2:
The exhaust pipe serves multiple functions: it conducts exhaust gases and simultaneously acts as a pulsation reservoir for noise attenuation. The reservoir portion of the exhaust pipe is used dual-purpose for both exhaust flow and acoustic dampening, eliminating the need for dedicated noise control components
2Object-affected harmful factors
If holes are provided on the exhaust pipe to allow sound waves to exit while limiting exhaust gas flow, then acoustic attenuation is improved, but exhaust gas may leak through the holes
Solution Approach 1:
The patent extracts the acoustic attenuation function from the exhaust gas flow path by creating a separate pulsation reservoir. Sound waves are allowed to exit through the reservoir opening while the main exhaust gas flow continues through the primary path, separating the acoustic function from the gas flow function to prevent leakage
Solution Approach 2:
The pulsation reservoir acts as an intermediary between the exhaust gas flow and the external environment. It provides a controlled interface where sound waves can be attenuated while maintaining the integrity of the exhaust gas containment, mediating between noise control requirements and gas flow integrity
3Object-affected harmful factors
If the reservoir volume is increased to improve noise attenuation, then acoustic performance is improved, but the device complexity and space requirements increase
Solution Approach 1:
The exhaust pipe itself is utilized as the pulsation reservoir, eliminating the need for a separate reservoir structure. This multi-functional approach provides the necessary reservoir volume for noise attenuation without adding structural complexity or requiring additional space-beside components
Solution Approach 2:
The exhaust system serves itself by using its own existing volume (the exhaust pipe) as the pulsation reservoir. The system utilizes its inherent structural capacity for noise attenuation without requiring external resources, additional components, or increased 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
The solution effectively reduces noise by re-circulating diverted gases back into the exhaust system, minimizing leakage and weight, while maintaining efficient noise attenuation without introducing new noise sources.
Implementation Method 1
a minimum reservoir volume (Vmin) to inlet area (A) ratio is greater than or equal to 100 mm
Implementation Method 2
re-circulating diverted gases back into the exhaust system
Data Source
AI summary
A vehicle exhaust system and method of minimizing a leaked mass flow comprising an exhaust component defining a central axis and having an inner surface and an outer surface, such that the inner surface defines a primary exhaust gas flow path extending along the central axis from an inlet to an outlet, and a surface component having a hood spaced from the exhaust component to define a reservoir having a reservoir volume (V), the reservoir comprising a reservoir inlet fluidly coupled to the primary exhaust gas flow path and defining an inlet area (A), and a reservoir outlet fluidly coupled to an outside environment. The reservoir volume and inlet area having a defined relationship. The reservoir volume and a mass flow through the inlet area having a defined relationship.