Two-Cycle Engine Auxiliary Air Passage for Smooth Acceleration
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Solution Overview
Problem
Conventional stratified scavenging two-cycle engines fail to supply an air-fuel mixture with sufficient concentration for acceleration, leading to acceleration failure or engine stop, especially when suddenly accelerated from an idling state, due to residual air-fuel mixture dilution with pure air during scavenging.
Innovation Solution
A stratified scavenging two-cycle engine design featuring an auxiliary air passage with a circumferential groove on the outer circumference of a large-diameter column, allowing pure air to supplement the scavenging passage while the air valve is closed or minimally opened, reducing the air-fuel mixture amount during idling to concentrate it, and feeding it back through a mixture passage to maintain concentration during acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the air valve is completely closed during idling to supply pure air to the scavenging passage, then fuel consumption is reduced and exhaust gas is cleaned up, but the air-fuel mixture concentration becomes insufficient for acceleration when suddenly accelerated from idling
Solution Approach 1:
The air passage is segmented into two separate passages: a first air passage that supplies pure air to the scavenging passage, and a second air passage that supplies air to the mixture passage. This segmentation allows independent control of air supply to different components, enabling the engine to maintain proper air-fuel mixture concentration for acceleration while still achieving fuel savings during idling operation.
Solution Approach 2:
A mixture valve is introduced as an intermediary component in the second air passage to control the amount of air supplied to the mixture passage. This intermediary device enables precise regulation of the air-fuel mixture concentration, allowing the engine to deliver sufficient concentrated mixture for acceleration when needed while maintaining efficient idling operation.
2Reliability
If the air-fuel mixture is supplied to the crank chamber during idling, then the engine can maintain operation, but the residual mixture dilutes with pure air during scavenging, reducing the concentration available for acceleration
Solution Approach 1:
The system performs preliminary action by supplying concentrated air-fuel mixture to the crank chamber during the idling phase before acceleration is needed. The mixture valve controls the air supply to ensure the mixture remains concentrated, and this pre-prepared concentrated mixture is then available in the crank chamber when acceleration is required, eliminating the need for complex acceleration pumps.
3Productivity
If an acceleration pump is provided to temporarily increase fuel amount during acceleration, then sufficient air-fuel mixture concentration can be achieved, but the structure becomes complicated and cost increases
Solution Approach 1:
The invention extracts and eliminates the need for a separate acceleration pump by using the existing mixture valve and air passage configuration to control air supply. Instead of adding a complex pump system, the patent extracts the essential function of concentration control and implements it through the mixture valve's regulation of air flow to the mixture passage, thereby achieving acceleration performance with a simpler structure.
Data Source
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AI summary
A stratified scavenging two-cycle engine (1) includes: an air passage (700) for delivering pure air to a scavenging passage (9); an air valve (430) for opening and closing the air passage (700); and an auxiliary air passage (100) for delivering the pure air to the scavenging passage (9) when the air valve (430) is completely closed. An amount of air for air-fuel mixture sucked in a crank chamber is reduced to increase the concentration of the air-fuel mixture, and air that supplements the reduced amount of the air for air-fuel mixture is fed into the scavenging passage (9) through the auxiliary air passage (100), which enables the engine to be smoothly accelerated even when being suddenly accelerated from an idling state with an appropriate concentration of the air-fuel mixture sucked in a cylinder chamber during idling.