Multi-sub-pipe Tailpipe Velocity Gradient Noise Reduction
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Solution Overview
Problem
The existing exhaust system for vehicles fails to effectively reduce gas flow noise outside the tailpipe due to a significant difference in velocity between discharged exhaust gas and peripheral air, which increases noise levels as engine performance improves.
Innovation Solution
A tailpipe design featuring a central pipe and surrounding sub-pipes with varying lengths and diameters, where the central pipe is shorter and wider than the sub-pipes, and all sub-pipes have the same or different exposed lengths, creating a gradual velocity gradient that reduces the velocity difference between exhaust gas and air, thereby minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single tailpipe is used for exhaust gas discharge, then the structure is simple, but the velocity difference between exhaust gas and peripheral air is large causing increased noise
Solution Approach 1:
The tailpipe is segmented into multiple sub-pipes (first, second, and third sub-pipes) with different lengths and diameters. This segmentation allows exhaust gas to be discharged through multiple pathways simultaneously, creating a gradual velocity gradient that reduces the velocity difference between exhaust gas and peripheral air, thereby reducing gas flow noise while maintaining structural efficiency.
Solution Approach 2:
Different portions of the tailpipe structure have different local qualities - the first sub-pipe has a larger diameter and different length compared to the second and third sub-pipes. This local variation in dimensions creates different discharge velocities at different locations, forming a gradual velocity gradient that mitigates noise while preserving overall structural simplicity.
2Power
If engine rotational speed is increased to improve performance, then power output is improved, but exhaust gas velocity increases causing increased noise
Solution Approach 1:
The multi-sub-pipe structure segments the exhaust flow into multiple streams with different velocities. Even when engine rotational speed increases and overall exhaust velocity increases, the segmentation ensures that not all exhaust gas discharges at the same high velocity - the gradient effect distributes the velocity increase across multiple pathways, reducing the noise impact.
Solution Approach 2:
The invention changes the physical parameters of the discharge structure by varying the diameters and lengths of different sub-pipes. This parameter variation creates a velocity gradient that counteracts the uniform velocity increase caused by higher engine speeds, allowing power improvement while controlling noise through structural parameter optimization.
3Object-affected harmful factors
If multiple sub-pipes with different lengths are used, then velocity gradient is formed reducing noise, but manufacturing complexity increases
Solution Approach 1:
The multiple sub-pipes are arranged in a nested configuration where they are positioned concentrically or in close proximity to each other within the tailpipe assembly. This nesting approach allows the complex multi-length, multi-diameter structure to be manufactured and assembled as an integrated unit, reducing manufacturing complexity despite the varied dimensions required for 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
The design significantly reduces gas flow noise by creating a gradual velocity gradient and promoting rapid mixing of exhaust gas with peripheral air through a vortex, effectively lowering noise levels.
Implementation Method 1
A velocity gradient is formed to be gradual by decreasing a difference between a velocity of exhaust gas discharged through the sub-pipes of the tailpipe, a velocity of exhaust gas discharged through the central pipe, and a velocity of peripheral air, thereby significantly reducing gas flow noise outside of the tailpipe.
Implementation Method 2
the exhaust gas is rapidly mixed with the peripheral air by a vortex caused by the global velocity gradient, thereby quickly reducing noise of the exhaust gas
Data Source
AI summary
A tailpipe for a vehicle, which has a tubular body may include a central pipe positioned in the body, and a plurality of sub-pipes which is disposed to surround an outer circumferential surface of the central pipe.