Fuel Injection On-Time Determination in Gaseous Engines
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Solution Overview
Problem
Current methods for determining fuel injection on-time in gaseous-fuelled internal combustion engines are inaccurate due to the influence of in-cylinder pressure variations, which affect the amount of fuel injected, leading to inconsistencies in combustion efficiency and engine performance.
Innovation Solution
A method that uses look-up tables to store predetermined injection on-time values based on gaseous fuel rail pressure and fuelling amount, with interpolation techniques to determine the desired injection on-time, considering parameters that correlate to in-cylinder pressure, such as intake manifold pressure and timing for start of injection, to accurately meter fuel into the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If injection pressure is reduced for gaseous fuels to decrease parasitic load, then energy consumption is reduced, but fuel injection accuracy deteriorates due to increased sensitivity to in-cylinder pressure variations
Solution Approach 1:
The system changes the control parameter from fixed injection pressure to variable injection pressure based on in-cylinder pressure conditions. By dynamically adjusting injection pressure according to the operating conditions and in-cylinder pressure measurements, the system maintains accurate fuel metering while minimizing parasitic load across different engine states.
Solution Approach 2:
The system implements feedback control by measuring in-cylinder pressure and using this information to adjust the injection pressure and injection on-time. The controller continuously monitors actual fuel injection mass and compares it with the target value, making real-time corrections to achieve accurate fuel metering despite variations in in-cylinder pressure.
2Productivity
If injection pressure is increased to improve fuel atomization and combustion efficiency, then combustion efficiency is improved, but parasitic load increases
Solution Approach 1:
The system dynamically adjusts injection pressure based on actual operating conditions rather than using a fixed high pressure. By optimizing injection pressure to match the specific combustion requirements at different engine states, the system achieves good combustion efficiency while minimizing unnecessary parasitic load from excessively high injection pressures.
Solution Approach 2:
The system transitions from static injection pressure control to dynamic injection pressure control that adapts to changing engine conditions. The injection pressure is continuously adjusted based on real-time measurements of in-cylinder pressure, fuel mass, and operating parameters to optimize the balance between combustion efficiency and energy consumption.
3Quantity of substance
If injection on-time is extended to compensate for lower injection pressure, then fuel delivery is improved, but combustion timing precision deteriorates
Solution Approach 1:
The system uses feedback control to continuously monitor actual fuel mass injected and adjust injection on-time accordingly. By comparing actual fuel delivery with target values and making real-time corrections to injection on-time, the system maintains precise combustion timing while ensuring accurate fuel delivery, preventing the timing precision deterioration that would occur with simple on-time extension.
Data Source
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AI summary
The present invention relates to a method and apparatus for determining the fuel injection on-time to accurately meter fuel injected directly into the combustion chamber of a gaseous fuelled internal combustion engine. The fuel injection on-time is determined by interpolating between values retrieved from two of a plurality of predetermined look-up tables, which each define fuel injection on-time as a function of gaseous fuel rail pressure and fuelling amount. Each table corresponds to a fixed value of a third parameter that correlates to in-cylinder pressure.