Muffler Shell Main Body Vapor Discharge Design
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Solution Overview
Problem
Conventional muffler shell main bodies with non-circular cylindrical cross sections, defined by alternating small and large arc portions, face deformation due to vapor pressure rise from water accumulation between inner and outer shells, as existing designs prevent effective vapor discharge, leading to pressure buildup and potential deformation.
Innovation Solution
A shell main body design featuring an inner and outer shell formed from double-rolled flat plates with strategically positioned shell overlap portions, allowing for vapor discharge through clearances formed between the shells, which are spot-welded at intervals to manage pressure and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the inner shell and outer shell are closely contacted at small arc portions to prevent water entry, then water intrusion is reduced, but vapor discharge is blocked causing pressure buildup and shell deformation
Solution Approach 1:
The shell structure is segmented into small arc portions and large arc portions with different functions. The small arc portions provide close contact for water prevention, while the large arc portions create gaps for vapor discharge, dividing the shell into functional zones that simultaneously address both requirements
Solution Approach 2:
Different regions of the shell are given different qualities: small arc portions have close contact between inner and outer shells to prevent water entry, while large arc portions have gaps to allow vapor discharge. This local differentiation resolves the contradiction by applying different structural characteristics to different locations
2Strength
If end plates are welded to outer shell to ensure structural integrity, then structural strength is improved, but gaps form between end plates and inner shell allowing water and vapor accumulation
Solution Approach 1:
The harmful effect of complete sealing is extracted by intentionally leaving gaps between the end plates and inner shell. These gaps, while allowing water and vapor entry, prevent pressure buildup by enabling discharge paths, thus removing the harmful accumulation effect while maintaining structural integrity through the welded outer shell
3Object-affected harmful factors
If shell overlap portions are spot-welded at intervals to allow vapor discharge, then vapor pressure is reduced, but manufacturing complexity increases
Solution Approach 1:
Instead of completely sealing all overlap portions or leaving them entirely open, spot-welding at intervals provides partial sealing that is sufficient for structural integrity while maintaining adequate gaps for vapor discharge. This partial action achieves the necessary balance without excessive manufacturing complexity
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 effectively suppresses vapor pressure rise by allowing vapor discharge, preventing shell deformation and reducing manufacturing costs while maintaining noise reduction and leak prevention.
Implementation Method 1
water vapor in exhaust gas is cooled off into the water due to contact with a low-temperature shell wall of the muffler
Implementation Method 2
the water that has entered the gaps 104a, 104b, 105a, and 105b is heated by high-temperature exhaust gas passing through the muffle to vaporize
Implementation Method 3
water enters the gaps 104a, 104b, 105a, and 105b formed between the inner shell 101 and the outer shell 102 due to capillary phenomenon through the gaps between the end plates and the inner shell 101
Data Source
AI summary
The shell main body for a muffler includes an inner shell in a cylindrical shape with a cross-section of an imperfect circle defined by small arc portions alternating with large arc portions; and an outer shell wrapping the inner shell and formed in a cylindrical shape similar to the inner shell. An end portion of the inner shell and an end portion of the outer shell are overlapped in a circumstantial direction of the shell main body to form a shell overlap portion that is capable of discharging vapor in a gap of the large arc portions formed between the inner shell and the outer shell into one of an outside and an inside of the shell main body. This shell overlapping portion is located in one of the small arc portions.