Muffler Constricted Part Suppresses Standing Waves
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Solution Overview
Problem
Conventional mufflers for internal combustion engines face challenges in reducing low-frequency noise due to standing waves, which can lead to increased weight and layout complications when larger capacities or additional mufflers are used.
Innovation Solution
The muffler design incorporates constricted and tapered parts in the inlet and outlet pipes to uniformly direct sound reflections, minimizing standing wave generation and pressure loss, without the need for increased capacity or weight, and includes small bores to further reduce noise and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the main muffler capacity is increased or a sub muffler is additionally provided to reduce low-frequency noise, then noise reduction performance is improved, but weight increases and layout within the space under the floor is significantly affected
Solution Approach 1:
The patent applies local quality by creating a constricted part with a smaller cross-sectional area at a specific location within the muffler body, rather than uniformly increasing the entire muffler capacity. This localized modification changes the acoustic characteristics to suppress standing waves and reduce low-frequency noise while maintaining the original muffler size and weight.
2Object-affected harmful factors
If the main muffler capacity is increased or a sub muffler is additionally provided to reduce low-frequency noise, then noise reduction performance is improved, but layout within the space under the floor is significantly affected
Solution Approach 1:
The patent segments the muffler internal structure by dividing it into different sections with varying cross-sectional areas, including a constricted part and expansion chambers. This segmentation creates acoustic impedance variations that suppress standing waves without requiring additional muffler components or complex layout arrangements.
3Object-affected harmful factors
If conventional muffler design is used to reduce exhaust noise, then noise reduction is achieved, but standing waves are generated causing muffled sound inside the vehicle
Solution Approach 1:
The patent changes the geometric parameters of the muffler by introducing a constricted part with a specific cross-sectional area that is smaller than the inlet and outlet pipe cross-sectional areas. This parameter change creates acoustic impedance variations that suppress standing wave formation and reduce low-frequency noise while maintaining effective exhaust noise reduction.
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 design effectively reduces exhaust noise and standing wave formation, minimizing weight increase and layout impact, while maintaining efficient noise reduction without the need for larger capacities or additional components.
Implementation Method 1
the at least one constricted part makes it possible to inhibit a sound reflection from reflecting in an uniform direction
Implementation Method 2
minimize pressure loss (inlet loss) in the constricted part
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A muffler for an internal combustion engine includes an outer shell, an inlet pipe, an outlet pipe, and at least one constricted part. The at least one constricted part is provided in at least one of the inlet pipe and the outlet pipe on an open side thereof opening toward an inside of the outer shell. The at least one constricted part has a cross-sectional area smaller than a cross-sectional area of the at least one of the inlet pipe and the outlet pipe, which is provided with the at least one constricted part.