Reverse Resonator for Uniform Engine Exhaust Noise Attenuation
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Solution Overview
Problem
Conventional automobile mufflers lack reverse cavity resonator configurations, leading to inadequate noise cancellation and directional biasing issues, as they fail to provide uniform noise reduction using active noise cancellation techniques.
Innovation Solution
The implementation of a reverse resonator apparatus with a coaxial configuration that encircles the engine exhaust, utilizing a fan and speaker to deliver anti-noise signals uniformly around the exhaust output, either passively or actively, to effectively attenuate noise through a mixing volume, and includes digital signal processing for optimized noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional muffler designs are used, then the structure is simple, but noise cancellation is inadequate and exhibits directional biasing
Solution Approach 1:
The reverse resonator is nested within the exhaust system by positioning it downstream of the exhaust outlet, where it encircles the exhaust flow. The resonator chamber is integrated into the exhaust path, with the exhaust flow passing through the chamber in a reverse direction relative to conventional resonators, creating a compact nested configuration that enhances noise cancellation without adding significant structural complexity
Solution Approach 2:
The resonator is configured to operate in reverse by directing exhaust flow through the resonator chamber in the opposite direction of conventional resonators. This inversion allows the resonator to effectively cancel noise by creating destructive interference patterns that propagate upstream, counteracting the directional biasing problem of conventional designs and providing more uniform noise reduction in all directions
2Object-affected harmful factors
If active noise cancellation is implemented, then noise attenuation is enhanced, but device complexity increases
Solution Approach 1:
The system utilizes the engine exhaust itself as the noise source to be canceled, eliminating the need for separate noise generation equipment. The exhaust flow serves dual purposes: it is both the harmful noise carrier and the medium through which the cancellation effect is achieved, as the resonator modifies the exhaust flow's acoustic properties to create destructive interference
Solution Approach 2:
The resonator employs mechanical vibration principles by creating standing waves within the resonator chamber that resonate at specific frequencies matching the engine noise. This mechanical resonance approach provides enhanced noise attenuation through passive acoustic mechanisms, reducing the need for complex active electronic control systems while maintaining effective noise cancellation
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 provides consistent and enhanced noise cancellation effects, superior to conventional methods, by ensuring uniform noise reduction in all radial directions from the engine exhaust, improving both passive and active noise attenuation capabilities.
Implementation Method 1
These reflected sound waves then cancel out new sound waves generated by the automobile engine in a process known as destructive interference
Implementation Method 2
reverse cavity resonation can provide significant noise cancellation effects in both passive and active arrangements
Data Source
AI summary
Techniques involve attenuating noise from engine exhaust from an engine. For example, an apparatus includes a first tube having an input end which receives the engine exhaust from the engine, and an output end which outputs the engine exhaust. The apparatus further includes a second tube which encircles the output end of the first tube. The second tube has an exhaust end through which the engine exhaust outputted by the output end of the first tube is allowed to escape, and a resonator end which is opposite the exhaust end. The apparatus further includes a reverse resonator disposed at the resonator end of the second tube. The reverse resonator defines a reverse resonator chamber and a reverse resonator chamber diameter which is larger than a second tube diameter defined by the second tube.