Exhaust Pipe Attachment for Rigidity and Thermal Stress Reduction
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Solution Overview
Problem
Existing exhaust system pipes face challenges with thermal load differences between the exhaust pipe and the tubular housing, leading to high alternating thermal stresses and potential gas tightness issues, while also requiring increased dimensional stability and cost-effective muffler design.
Innovation Solution
The exhaust pipe is equipped with a separately manufactured attachment that creates a cavity extending less than 180° around the pipe body, enhancing rigidity and allowing for acoustic coupling, which can be filled with sound-absorbing material to function as a muffler, with a welded connection along the longitudinal direction to minimize thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a tubular housing is used to enclose the exhaust pipe for muffler function, then soundproofing capability is improved, but the housing is exposed to high alternating thermal loads causing connection reliability issues
Solution Approach 1:
The exhaust pipe is segmented into multiple sections along its longitudinal axis, with attachment points for the tubular housing positioned at specific segments. This allows the thermal expansion to be distributed across multiple connection points rather than concentrated at a single location, reducing the alternating thermal load on each individual connection.
Solution Approach 2:
The patent introduces intermediate connection structures between the tubular housing and the exhaust pipe. These intermediaries act as thermal buffers that reduce the direct transmission of high alternating thermal loads from the exhaust pipe to the housing connections, thereby improving connection reliability while maintaining soundproofing functionality.
2Strength
If the attachment extends over more than 180° circumferentially, then rigidity is improved, but the design complexity and manufacturing cost increase
Solution Approach 1:
The attachment is designed to extend over a specific circumferential range (more than 180°) at strategically selected locations along the exhaust pipe rather than uniformly around the entire pipe. This localized approach provides sufficient rigidity and dimensional stability in critical areas while minimizing overall design complexity and manufacturing cost.
Solution Approach 2:
The patent utilizes the longitudinal dimension of the exhaust pipe in addition to the circumferential dimension. By positioning multiple attachments at different longitudinal locations with varying circumferential extensions, the design achieves enhanced rigidity through spatial distribution rather than requiring a single complex full-circumference attachment.
3Stress or pressure
If the attachment is welded along the longitudinal direction, then thermal stresses are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The attachment structures are pre-positioned and pre-aligned with the exhaust pipe before the welding process. This preliminary positioning ensures that the longitudinal welded connections are established with proper alignment, reducing the actual welding precision requirements during the final assembly while still achieving reduced thermal stresses through the longitudinal weld configuration.
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 significantly increases the pipe's rigidity, reduces thermal stresses, and allows for a compact, cost-effective muffler implementation with improved soundproofing capabilities, enabling the exhaust pipe to be installed flexibly within the exhaust system.
Implementation Method 1
the attachment being attached to the pipe body on the respective side of the pipe body by means of a welded connection which extends in the longitudinal extension of the pipe body along the pipe body
Implementation Method 2
which can be filled with sound-absorbing material to function as a muffler
Data Source
Figure 1~2
Figure 3~4
Figure 5a~6e
AI summary
The present invention relates to an exhaust gas-carrying pipe (11) of an exhaust system (1) of an internal combustion engine (9), comprising an exhaust gas-carrying pipe body (15) and at least one attachment part (12) separate from the pipe body (15), which is attached laterally to the pipe body (15) such that a cavity (13) is arranged on the outside of the pipe body (15), at least partially bounded by the attachment part (12), and which extends in the circumferential direction (14) of the pipe body (15) over less than 360°. The pipe body serves as a stiffening element and as a silencer, which acts as a closed resonance chamber via perforations in the exhaust gas-carrying pipe (11).