Segmented Exhaust Silencer Catalyst for Hand-Held Tools
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Solution Overview
Problem
Hand-held tools with mixed-lubricated internal combustion engines face challenges in meeting strict exhaust gas regulations due to limited installation space, high exhaust gas temperatures, and fluctuating gas compositions, which existing exhaust silencers struggle to address effectively.
Innovation Solution
A compact exhaust silencer design featuring a catalytic converter with a flow body composed of wire bodies, where one portion is heavily coated for catalytic conversion and the other portion is lightly coated or uncoated for particle reduction, allowing for efficient catalytic conversion and particle reduction without excessive heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a catalytic converter is used to reduce exhaust gas emissions in hand-held power tools, then hydrocarbons and nitrogen oxides are converted, but the exhaust silencer becomes excessively hot and particles accumulate causing clogging
Solution Approach 1:
The flow body is divided into two distinct sections: a first section with heavy catalytic coating for converting hydrocarbons and nitrogen oxides, and a second section with light or no catalytic coating for particle reduction and heat dissipation. This segmentation allows the catalytic function and thermal management function to be separated spatially, enabling effective emissions reduction without excessive heating of the entire exhaust silencer.
2Volume of moving object
If the exhaust silencer is made compact to fit hand-held power tools, then installation space requirements are met, but the catalyst lifespan is reduced and clogging occurs more frequently
Solution Approach 1:
Different regions of the flow body are assigned different coating densities tailored to their specific functions. The first section receives heavy catalytic coating optimized for gas-phase pollutant conversion, while the second section receives light or no coating to facilitate particle passage and prevent clogging. This local differentiation allows the compact exhaust silencer to maintain high reliability despite its small size.
3Productivity
If heavy catalytic coating is applied to the entire flow body, then catalytic conversion efficiency is maximized, but particle reduction capability is compromised and clogging increases
Solution Approach 1:
The flow body is segmented into two functional zones: the first section with heavy catalytic coating dedicated to converting hydrocarbons and nitrogen oxides, and the second section with light or no coating dedicated to allowing particles to pass through without accumulation. This segmentation enables the system to simultaneously achieve high catalytic conversion efficiency and effective particle reduction, preventing clogging while maintaining productivity.
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 achieves rapid and effective catalytic conversion of hydrocarbons and nitrogen oxides while reducing particles, extending catalyst life and preventing clogging, while maintaining a compact and robust structure suitable for hand-held tools.
Implementation Method 1
At least one first section (32) of the flow body (31) is coated with a catalytically active coating
Implementation Method 2
The second section (33) has a smaller amount of catalytically active coating by volume than the first section (32)
Data Source
Figure 1~4
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Figure 9~16
AI summary
An exhaust silencer (23) has an exhaust inlet (24), an exhaust outlet (25), and a catalyst (26) arranged in the flow direction (40) between the exhaust inlet (24) and the exhaust outlet (25). The catalyst (26) has at least one flow body (31) comprising at least one wire body (34, 35). At least a first sub-section (32) of the flow body (31) is coated with a catalytically active coating. The flow body (31) also has a second sub-section (33) which has a smaller amount of catalytically active coating per unit volume than the first sub-section (32).