Dual Fuel Injection Valve Fixed Interlace Angle
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Solution Overview
Problem
Pilot-ignited high-pressure direct injection gaseous-fuelled engines face variability in engine speed and NOx emissions due to periodic variations, particularly at low load conditions, which can lead to irregular engine operation and combustion instability, especially when the dual fuel injection valves are positioned off-center or inclined, causing uneven fuel distribution and interaction with the combustion chamber walls.
Innovation Solution
A dual fuel injection valve design with a fixed radial position of the outer needle relative to the valve body, utilizing a keying member to maintain a constant interlace angle between the fuel orifices, preventing rotation of the outer needle and ensuring consistent fuel injection, thereby stabilizing engine performance and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer needle is allowed to rotate freely to adapt to different cylinder characteristics, then ease of operation is improved, but combustion stability deteriorates due to variations in interlace angle causing periodic engine speed and NOx emissions variations
Solution Approach 1:
Instead of allowing the outer needle to rotate freely to adapt to different cylinders, the patent inverts the approach by providing a keying member that prevents rotation and maintains a fixed, optimized interlace angle. This fixed configuration eliminates the periodic variations in engine speed and NOx emissions that caused combustion instability, while the keying member design allows the entire injector to be rotated to different cylinders.
2Device complexity
If the dual fuel injection valve is positioned off-center or inclined to fit cylinder head space constraints, then device complexity is reduced, but fuel distribution uniformity deteriorates causing irregular engine operation
Solution Approach 1:
The patent accommodates off-center or inclined positioning by introducing asymmetry through the keying member configuration. The keying member is positioned at a specific angle relative to the injector axis, and the injector can be rotated to different cylinders with each cylinder receiving a customized orientation. This allows the injection valve to fit space constraints while maintaining proper fuel distribution for each specific cylinder geometry.
3Reliability
If the outer needle is fixed in radial position to maintain constant interlace angle, then combustion stability is improved, but ease of manufacture deteriorates due to additional keying mechanisms
Solution Approach 1:
The patent segments the injector into distinct components: the valve body, the outer needle, and the keying member. This segmentation allows the keying member to be manufactured separately and assembled onto the outer needle, simplifying the overall manufacturing process. The keying member can be produced using standard machining operations and then fitted to the outer needle, avoiding the need for complex integrated manufacturing.
Data Source
Figure 1~2
Figure 3~4B
Figure 4C~4F
AI summary
A dual fuel injection valve with concentric needles comprises an inner needle and an outer needle surrounding the inner needle, both needles being located inside the injection valve body. The valve is provided with a first set and a second set of orifices for separately injecting two different fuels directly into the combustion chamber of an internal combustion engine. The outer needle is fixed against rotation with respect to the injection valve body such that an interlace angle between the centerlines of the first series of orifices and second series of orifices is set at different predetermined angles to reduce methane emissions.