Uniflow Scavenging 2-Stroke Engine Fuel Injection
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Solution Overview
Problem
In uniflow scavenging 2-cycle engines, uneven fuel gas concentration in the combustion chamber leads to flame-out and abnormal combustion due to varying flow velocities of active gas, causing localized fuel gas dilution or over-concentration.
Innovation Solution
The engine features a fuel injection unit with injection ports outside the cylinder, where the flow velocity differences are compensated by varying the opening areas and intervals of injection ports along the piston's stroke direction, ensuring uniform fuel gas distribution across the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple injection ports are provided at different positions in the scavenge port to diffuse fuel gas, then the mixing of fuel gas and active gas is improved, but the fuel gas concentration becomes uneven due to varying flow velocities at different positions, causing flame-out or abnormal combustion
Solution Approach 1:
The invention applies local quality by making the injection ports asymmetric in design - specifically, the injection port at the end closer to the piston has a larger opening area than the port at the other end. This asymmetric configuration compensates for the different flow velocities of active gas at different positions, ensuring that fuel gas is injected at appropriate rates to each region despite the velocity variations, thereby maintaining uniform fuel gas concentration and preventing combustion instability
Solution Approach 2:
The invention changes the parameter of injection port opening area to compensate for flow velocity variations. By making the opening area of the injection port closer to the piston larger than that of the other port, the system adjusts the local injection characteristics to match the local flow conditions, achieving uniform fuel distribution despite position-dependent velocity differences
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 configuration ensures a uniform fuel gas concentration in the combustion chamber, preventing flame-out and abnormal combustion by optimizing the injection port design to match flow velocities and areas.
Implementation Method 1
a plurality of injection ports which inject a fuel gas into active gas to be suctioned into the scavenge ports are provided on the outside of the cylinder rather than on the inner circumferential surface, wherein circulation tubes, through which the fuel gas flows
Data Source
Figure 1
Figure 2A~2B
Figure 2C~3A
AI summary
A uniflow scavenging 2-cycle engine includes a cylinder (110) inside in which a combustion chamber is formed; a piston which slides within the cylinder; a scavenge port (122) which is provided on one end side in a stroke direction of the piston in the cylinder to suck an active gas into the combustion chamber in accordance with the sliding movement of the piston; and an injection unit (126) which injects a fuel gas into the active gas suctioned to the scavenge port and is provided on an inner circumferential surface of the scavenge port or on the outside of the cylinder rather than the inner circumferential surface. Further, the amount of the fuel gas injected by the injection unit on the other end side in the stroke direction is larger than the amount of fuel gas injected by the injection unit on one end side in the stroke direction. With such a configuration, it is possible to provide a uniflow scavenging 2-cycle engine which can suppress the flame-out or abnormal combustion by equalizing the concentration of the fuel gas that reaches the combustion chamber from the scavenge port.