Movable Scavenging Port for Two-Stroke Engine Fuel Adaptation
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Solution Overview
Problem
In uniflow scavenging type two-cycle engines, the optimal timing for active gas flow into the cylinder can differ between liquid fuel and fuel gas, making it challenging to design the scavenging port position effectively for both fuels, which affects engine efficiency due to variations in expansion and scavenging periods.
Innovation Solution
A movable scavenging port system, utilizing a hydraulic mechanism to adjust the position of the scavenging ports in the stroke direction, allowing for optimal timing of active gas flow based on the operating conditions, whether in diesel or gas operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scavenging port position is designed for liquid fuel operation, then the expansion stroke is optimized for diesel mode, but the active gas flow timing becomes inappropriate for fuel gas operation
Solution Approach 1:
The scavenging port is made movable rather than fixed, allowing its position to be dynamically adjusted along the piston stroke direction. A driving mechanism changes the scavenging port's position according to the operating mode (diesel or gas), enabling optimal active gas flow timing for each fuel type while maintaining high engine efficiency
2Adaptability or versatility
If the scavenging port position is fixed, then the engine structure is simple, but the active gas flow timing cannot be optimized for different fuel types
Solution Approach 1:
The scavenging port is made movable rather than fixed, allowing its position to be dynamically adjusted along the piston stroke direction. A driving mechanism changes the scavenging port's position according to the operating mode (diesel or gas), enabling optimal active gas flow timing for each fuel type while maintaining high engine efficiency
Solution Approach 2:
A driving mechanism serves as an intermediary between the control system and the scavenging port, translating operational requirements into positional adjustments. This mediator enables the scavenging port to adapt to different fuel types without requiring complete redesign of the engine structure
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
Enables appropriate timing of active gas flow into the cylinder, enhancing engine efficiency by securing a long expansion stroke in diesel mode and reducing preignition in gas mode, thus improving overall performance.
Implementation Method 1
a movable scavenging port system, utilizing a hydraulic mechanism to adjust the position of the scavenging ports in the stroke direction
Implementation Method 2
When fuel is burned in a combustion chamber and the piston pushed by combustion gas generated by the combustion moves to a position closer to the bottom dead center than the scavenging port
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The uniflow scavenging type two-cycle engine includes: a cylinder (110); a scavenging port (118) which is formed in the cylinder, opens in a process of movement of a piston (114) toward a bottom dead center, and causes active gas to flow into the cylinder; and a mover which displaces an opening position (118a) on a piston top dead center-side of the scavenging port in a stroke direction of the piston.