Air Filter Base Duct Routing for Emission Control
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Solution Overview
Problem
Existing hand-held working devices with internal combustion engines face challenges in achieving good exhaust gas values and efficient fuel supply due to the complexity of air and mixture duct configurations, which often result in fuel being sucked into the air duct, leading to poor emission values.
Innovation Solution
A hand-held working device with an internal combustion engine and air filter design where the air and mixture ducts are routed in the interior space between the intermediate flange and the air filter base, allowing for adjustable duct lengths to oscillate in phase, preventing fuel from being sucked into the air duct, and utilizing a simple structure with fewer components and effective sealing to maintain good emission values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air duct and mixture duct are extended into the clean room of the air filter, then the duct lengths can be matched to prevent fuel from being sucked into the air duct, but the structure becomes more complex and requires additional space
Solution Approach 1:
The patent merges the air duct and mixture duct routing within the air filter base structure itself, using the base as a common housing for both channels. This integration eliminates the need for separate external ductwork while maintaining the required duct lengths for proper pressure wave synchronization, thus improving emission values without proportionally increasing device complexity
Solution Approach 2:
The air filter base serves multiple functions: it houses the filter element, provides structural support, and acts as a routing channel for both the air duct and mixture duct. This multi-functionality allows the ducts to be extended into the clean room while avoiding the need for additional dedicated housing structures, balancing reliability improvement with complexity control
2Device complexity
If the air duct and mixture duct are routed in the interior space between the intermediate flange and air filter base, then fewer components are required and space is efficiently utilized, but the duct length adjustment for pressure wave synchronization becomes more difficult
Solution Approach 1:
The duct routing is segmented into distinct sections: portions of the air duct and mixture duct are routed through the intermediate flange and air filter base structure. This segmentation allows the ducts to be integrated into the existing component assembly, reducing the total number of separate parts while maintaining sufficient length for pressure wave synchronization through careful routing design
3Reliability
If the duct lengths are adjusted to synchronize pressure waves and prevent fuel from entering the air duct, then good emission values are achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the duct lengths as fixed design parameters during the design phase, routing the air duct and mixture duct through the intermediate flange and air filter base to achieve the required lengths for pressure wave synchronization. By establishing these lengths as inherent design parameters rather than adjustable variables, the manufacturing precision requirements are reduced while still achieving good emission values
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 achieves good emission values by ensuring that pressure waves in the mixture and air ducts oscillate in phase, preventing fuel from entering the air duct, and provides a simple, efficient structure for fuel supply and sealing, thereby improving the overall performance of the hand-held device.
Implementation Method 1
the duct lengths of the air duct and mixture duct can easily be adjusted in such a way that the pressure waves occurring during operation in the mixture duct and in the air duct oscillate in phase
Implementation Method 2
At least one seal is molded onto the bottom of the air filter, which rests against the intermediate flange and seals the interior
Data Source
Figure 1~3
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Figure 6~7
AI summary
A hand-held power tool has an internal combustion engine (15) and an air filter (38). The cylindrical filter element (39) of the air filter (38) has an air filter base (40) at one end face, which, together with an intermediate flange (43) arranged on the air filter base (40), defines an interior space (85). A section (41) of a channel is guided within the interior space (85). The channel is bounded by at least one boundary wall (44) projecting transversely into the interior space (85) to the air filter base (40), which is formed on the intermediate flange (43) and/or on the air filter base (40) and bridges the distance (a) between the base (60) of the intermediate flange (43) opposite the air filter base (40) and the air filter base (40).