Anti-backflow Element Vortex Design for Two-Stroke Engine Fuel Control
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Solution Overview
Problem
Two-stroke internal combustion engines experience backflow of fuel towards the air filter due to pressure waves, leading to rapid reduction in filtering capacity and potential damage or deposits on the filter screens, despite the use of anti-backflow elements like elbow joints which can fraction fuel drops and allow them to reach the filter.
Innovation Solution
An anti-backflow element with a perimetral band and tangentially opening ducts creates a vortexual motion that diverts the reverse air/fuel flow back towards the carburetor, preventing fuel drops from reaching the air filter, and accumulates fuel for gravity-driven collection, ensuring it is reintroduced during the next intake phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an anti-backflow element consisting of an elbow joint is installed in the intake line, then fuel backflow towards the air filter is reduced, but fuel drops are fractioned and can still reach the air filter through the pressure wave
Solution Approach 1:
The anti-backflow element is divided into multiple functional sections: a first section with an elbow joint for initial flow redirection, and a second section with a screen for fuel drop separation. This segmentation allows the device to address both the bulk flow backflow and the fractioned fuel drops that penetrate the first section.
Solution Approach 2:
A screen is introduced as an intermediary component between the elbow joint and the air filter. This screen acts as a barrier that intercepts fuel drops fractioned by the pressure wave, preventing them from reaching the air filter while allowing the anti-backflow element to maintain its flow redirection function.
2Device complexity
If a simple elbow joint anti-backflow element is used, then device complexity is reduced, but fuel drops can pass through and damage the air filter
Solution Approach 1:
The anti-backflow element is divided into multiple functional sections: a first section with an elbow joint for initial flow redirection, and a second section with a screen for fuel drop separation. This segmentation allows the device to address both the bulk flow backflow and the fractioned fuel drops that penetrate the first section.
Solution Approach 2:
A screen is introduced as an intermediary component between the elbow joint and the air filter. This screen acts as a barrier that intercepts fuel drops fractioned by the pressure wave, preventing them from reaching the air filter while allowing the anti-backflow element to maintain its flow redirection function.
3Object-generated harmful factors
If the anti-backflow element forces fuel drops to collide against internal walls, then bulk fuel backflow is prevented, but fractioned drops remain suspended and can reach the air filter
Solution Approach 1:
A screen is introduced as an intermediary component between the elbow joint and the air filter. This screen acts as a barrier that intercepts fuel drops fractioned by the pressure wave, preventing them from reaching the air filter while allowing the anti-backflow element to maintain its flow redirection function.
Solution Approach 2:
The screen extracts and removes fuel drops from the air/fuel mixture flow by intercepting them before they can reach the air filter. This extraction function addresses the specific problem of fractioned fuel drops that survive the elbow joint collision mechanism.
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
Effectively prevents fuel from reaching the air filter, maintaining filter capacity and preventing damage, while being a simple and cost-effective solution.
Implementation Method 1
An anti-backflow element with a perimetral band and tangentially opening ducts creates a vortexual motion that diverts the reverse air/fuel flow back towards the carburetor
Implementation Method 2
accumulates fuel for gravity-driven collection, ensuring it is reintroduced during the next intake phase
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A device for supplying an internal combustion engine (1 ), comprising a carburettor(72) and an air filter (71 ) installed on an air intake line (70), through which the air filtered by the filter (71 ) is conveyed into the carburettor (72), and an anti-backflow element (8) located in series on the air intake line (70) between the carburettor (72) and the air filter (71 ), in which the anti- backflow element (8) exhibits an external casing (80) comprising a perimetral band (81 ) including at least a portion substantially circular in development closed by two side walls (82, 83), such as to internally define at least a compartment (84) in communication with the carburettor (72) through a duct (85) opening in the perimeteral band (81 ) and developing tangentially relative to the circularly developing portion, the compartment (84) also in communication with the air filter (71 ) through a first duct (86) opening in one of the side walls (82, 83).