Uniflow Scavenging 2-Cycle Engine Injection Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In uniflow scavenging two-cycle engines, the insufficient mixing of fuel gas and active gas can lead to pre-ignition and unburned gas emission, and the use of multiple injection ports can result in fuel gas blow-by through the exhaust port.
Innovation Solution
The engine employs a fuel injection unit with multiple injection ports positioned on the outer side of the cylinder, where the first and second injection units have staggered start and stop timings to ensure uniform diffusion of fuel gas and prevent blow-by, utilizing mixing tubes and switching valves to control the injection of premixed gas into the scavenge port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple injection ports are provided to uniformly diffuse the fuel gas, then the mixing uniformity is improved, but the fuel gas blow-by through the exhaust port occurs
Solution Approach 1:
The patent applies preliminary action by injecting fuel gas into the scavenge port before the active gas is suctioned into the cylinder. This allows the fuel gas to be pre-mixed with the scavenge air in the scavenge port, ensuring uniform diffusion before the mixture enters the cylinder. The injection timing is controlled to start before the scavenge port opens and continue during the suction stroke, preventing fuel gas blow-by through the exhaust port while achieving uniform mixing.
2Duration of action of moving object
If fuel gas is injected into the scavenge port before active gas suction, then the mixing time is secured, but the fuel gas may be ejected through the exhaust port
Solution Approach 1:
The patent applies dynamics by making the injection timing adjustable and adaptive. The injection start timing is set before the scavenge port opens, and the injection continues during the suction stroke. The injection timing can be adjusted based on engine operating conditions, allowing the system to optimize the balance between securing sufficient mixing time and preventing fuel gas ejection through the exhaust port.
Solution Approach 2:
The patent applies parameter changes by adjusting the injection timing parameters (start timing and duration) to prevent fuel gas ejection. By controlling the injection to start before the scavenge port opens and to continue during the suction stroke, the system changes the temporal parameters of fuel injection to ensure complete mixing before compression, while the injection stops before the exhaust port opens to prevent ejection.
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 effectively suppresses fuel gas blow-by while ensuring uniform mixing, reducing the risk of pre-ignition and unburned gas emission, and improves fuel efficiency by optimizing the injection timing and duration.
Implementation Method 1
the mixing between the fuel gas and the active gas is insufficient
Implementation Method 2
a premixed gas is generated by injecting the fuel gas into the active gas sucked from the scavenge port
Implementation Method 3
the combustion operation is performed by compressing the generated premixed gas
Implementation Method 4
the combustion operation is performed by compressing the generated premixed gas, and the piston reciprocates within the cylinder by the explosive pressure generated by the combustion operation
Data Source
Figure 1
Figure 2A~2B
Figure 2C~3
AI summary
A uniflow scavenging two-cycle engine includes a scavenge port which is provided on one end side in a stroke direction of a piston in a cylinder (110), and sucks an active gas; and a plurality of injection units (126g and 126f) which inject a fuel gas into the active gas sucked into the scavenge port and are provided on an inner circumferential surface of the scavenge port or on the outside of the cylinder compared to the inner circumferential surface, and have different positions of the piston in the stroke direction. Further, the plurality of injection units are divided into at least two sets of injection unit groups include a first injection unit group (160) and a second injection unit group (162), the first injection unit group being a set of one or a plurality of injection units located on the other end side in the stroke direction, and the second injection unit group being a set of one or a plurality of injection units located on one end side in the stroke direction, and the injection stop of the fuel gas is later in the injection unit of the first injection unit group than in the injection unit of the second injection unit group. With the configuration, it is possible to provide a scavenging two-cycle engine which suppresses blow-by of the fuel gas, while uniformly diffusing the fuel gas.