Hydrogen Engine Split Injection for Pre-Ignition Control
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Solution Overview
Problem
Hydrogen internal combustion engines face challenges with high risks of abnormal combustion, including pre-ignition, which can damage the engine, due to hydrogen's low ignition energy and the need for homogeneous fuel-air mixtures.
Innovation Solution
A method involving split hydrogen fuel injections before and after the intake valve closure, with adjustable injection parameters to enhance mixture homogeneity and ignition energy, using an engine control unit to adapt to pre-ignition detection and optimize injection times and amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen fuel is injected early (before intake valve closure) to improve mixture homogeneity, then combustion efficiency increases and NOx emissions reduce, but the risk of pre-ignition and backfire increases
Solution Approach 1:
The fuel injection process is segmented into multiple stages: a first injection before intake valve closure to establish initial mixture homogeneity, and a second injection after intake valve closure to top-up the mixture and reduce pre-ignition risk. This segmentation allows each injection to serve a specific function, resolving the contradiction between homogeneity and pre-ignition prevention.
Solution Approach 2:
The first injection is performed as a preliminary action before the intake valve closes, creating a leaner initial mixture that promotes homogeneity. This preliminary mixing action occurs when the cylinder is cooler and less prone to pre-ignition, while the subsequent second injection completes the mixing process safely after valve closure.
2Reliability
If hydrogen fuel is injected late (after intake valve closure) to reduce pre-ignition risk, then abnormal combustion decreases, but mixture homogeneity deteriorates
Solution Approach 1:
The injection process is divided into two segments where the second injection (after valve closure) focuses on reducing pre-ignition risk by injecting into a controlled, cooler environment, while the first injection (before valve closure) handles the homogeneity requirement. This segmentation allows each phase to optimize for its specific goal without compromising the other.
Solution Approach 2:
The injection parameters (timing, duration, quantity) are changed between the two injections. The first injection uses earlier timing and different quantity to promote mixing, while the second injection adjusts timing and quantity to complete mixing safely after valve closure, thereby achieving both homogeneity and pre-ignition prevention.
3Device complexity
If manifold injection or port injection is used to simplify the system, then device complexity reduces, but backfire risk and pre-ignition risk increase
Solution Approach 1:
The injection system uses a direct injector segmented into two injection events, replacing complex manifold/port injection systems. This single-component segmented approach maintains simplicity while eliminating backfire risk by ensuring all fuel injection occurs after the intake valve closes, preventing fuel from entering the intake manifold.
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
Reduces pre-ignition risks while maintaining engine performance and efficiency, ensuring reliable operation by adapting injection parameters based on operating conditions and pre-ignition detection.
Implementation Method 1
hydrogen is injected (directly and optionally also indirectly) into the cylinder, whereby a fuel-air mixture is formed
Implementation Method 2
an ignition is performed using a spark plug or the like, thus igniting the mixture and causing a combustion
Data Source
AI summary
A method of operating a hydrogen internal combustion engine having at least one cylinder with an intake valve and a direct injector for injecting hydrogen fuel directly into the cylinder. The method comprises performing a plurality of hydrogen fuel injections before an ignition during an engine cycle, wherein a first injection, with a first injection amount m1 and a first injection time t1 as first injection parameters, is performed before the intake valve is closed and a second injection, with a second injection amount m2 and a second injection time t2 as second injection parameters, is performed by the direct injector after the intake valve has been closed and before an ignition is performed. The method further comprises performing an adjustment process.