Exhaust Pipe Bend With Varying Diameter And Radius
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Solution Overview
Problem
Existing exhaust pipe systems for combustion engines face challenges in achieving optimal sound attenuation and flow noise reduction due to limitations in bend structure design, particularly in compact arrangements where space is constrained, and the need to balance diameter and bend radius for effective pressure loss and noise optimization.
Innovation Solution
The exhaust pipe design features a bend portion with varying diameters and radii, where the central bend portion has a smaller diameter and a larger bend radius for smooth flow guidance, and a sharper turn in the outlet bend to minimize flow detachment and noise, with geometric parameters adapted along the pipe length to optimize sound attenuation and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pipe diameter is reduced to improve low-frequency sound attenuation, then sound attenuation is improved, but flow velocity increases causing increased flow noise and pressure loss
Solution Approach 1:
The patent applies different diameters to different sections of the bend portion. The first bend portion has a first diameter while the second bend portion has a second diameter that is smaller than the first diameter. This local differentiation allows the first bend portion to maintain lower flow velocity for reduced flow noise, while the second bend portion provides improved low-frequency sound attenuation with its smaller diameter.
2Object-generated harmful factors
If the bend radius is increased to reduce flow noise and pressure loss, then flow noise and pressure loss are reduced, but the compact arrangement of the bent pipe is compromised
Solution Approach 1:
The patent employs different bend radii for different portions of the bend. The first bend portion has a first bend radius while the second bend portion has a second bend radius that is smaller than the first bend radius. This allows the first bend portion to provide smooth flow guidance with reduced flow noise, while the second bend portion achieves a sharper turn for compact spatial arrangement.
Solution Approach 2:
The bend portion is divided into two distinct sections: a first bend portion and a second bend portion. Each section has independently optimized parameters (diameter and bend radius) to fulfill different functions - the first section focuses on flow quality while the second section focuses on spatial compactness and sound attenuation.
3Speed
If the pipe diameter is increased in the bend section to reduce flow velocity, then flow velocity is reduced, but low-frequency sound attenuation is degraded
Solution Approach 1:
The patent uses different diameters in different bend portions to simultaneously address flow velocity and sound attenuation requirements. The first bend portion has a larger diameter to maintain acceptable flow velocity, while the second bend portion has a smaller diameter to provide effective low-frequency sound attenuation.
4Ease of manufacture
If a constant bend radius is used throughout the bend portion, then manufacturing is simplified, but flow detachment and flow noise cannot be optimized
Solution Approach 1:
The patent specifies different bend radii for different portions of the bend - a first bend radius for the first bend portion and a second bend radius for the second bend portion. This localized differentiation optimizes flow behavior in each section to reduce flow detachment, while still maintaining manufacturability through a relatively simple two-section design.
Data Source
AI summary
The exhaust pipe comprises an inlet pipe, an outlet pipe and a bend portion arranged between the inlet pipe and the outlet pipe. The bend portion comprises an inlet bend and an outlet bend, wherein a central bend portion defines an intermediate section of inlet bend and outlet bend and wherein the inlet bend and the outlet bend each cover 50 percent of the total bend angle covered by the bend portion. The central bend portion comprises a diameter, which is smaller than a diameter of the inlet bend and of the outlet bend in a bending plane. In addition a bend radius R of the bend portion varies along the bend portion such that a bend radius of the inlet bend is larger than a bend radius of the outlet bend.