Engine Control Apparatus for Low-Speed Pre-Ignition Prediction
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Solution Overview
Problem
Existing engine control systems fail to accurately predict low-speed pre-ignition events in combustion chambers, particularly under low-speed and high-load conditions, due to limitations in considering fuel adherence and recirculation gas amounts in current prediction formulas.
Innovation Solution
A controlling apparatus that calculates an auto-ignition index based on cylinder temperature and pressure, incorporates a wall-adhering fuel correction coefficient to account for fuel adherence, and uses oxygen concentration correction coefficients to predict low-speed pre-ignition, enabling more precise prediction and prevention strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intake air temperature is lowered to prevent low-speed pre-ignition, then pre-ignition is suppressed, but engine output is significantly reduced
Solution Approach 1:
The invention changes the prediction parameters from simple temperature/pressure to a comprehensive auto-ignition index that integrates temperature, pressure, and time factors through the Livengood-Wu integral. This allows for more precise prediction of low-speed pre-ignition without requiring excessive cooling that would reduce engine output.
Solution Approach 2:
The invention replaces mechanical/physical intervention (cooling the intake air) with a computational prediction system. By using the auto-ignition index calculation and correction coefficients, the system can predict pre-ignition risk and apply minimal corrections to ignition timing or fuel injection, rather than significantly altering intake air temperature, thus maintaining engine output while preventing pre-ignition.
2Reliability
If the amount of recirculation gas is increased to reduce oxygen concentration and prevent pre-ignition, then pre-ignition is suppressed, but combustion chamber temperature is raised which may induce pre-ignition
Solution Approach 1:
The invention implements a feedback mechanism where the auto-ignition index is calculated based on actual cylinder temperature and pressure measurements, and correction coefficients are applied based on predicted fuel adherence. This closed-loop prediction system allows for dynamic adjustment of ignition timing or fuel injection to prevent pre-ignition without requiring fixed increases in recirculation gas that would raise combustion chamber temperature.
Solution Approach 2:
The invention changes the approach from modifying recirculation gas amount to using correction coefficients that account for fuel adherence effects. By incorporating wall-adhering fuel correction coefficients into the auto-ignition index calculation, the system can predict pre-ignition risk more accurately and apply targeted corrections rather than broadly increasing recirculation gas, thus avoiding unnecessary temperature rise.
3Device complexity
If conventional prediction formulas are used without considering fuel adherence and recirculation gas amounts, then calculation is simple, but low-speed pre-ignition cannot be correctly predicted
Solution Approach 1:
The invention performs preliminary calculations of correction coefficients based on predicted fuel adherence amounts before finalizing the pre-ignition prediction. The wall-adhering fuel correction coefficient is calculated in advance using predicted fuel injection patterns and combustion chamber geometry, then applied to the auto-ignition index. This preliminary action ensures accurate prediction without requiring complex real-time measurements during combustion.
Solution Approach 2:
The invention segments the prediction process into distinct components: the base auto-ignition index calculation using Livengood-Wu integral, the wall-adhering fuel correction coefficient calculation, and the final combined prediction. By dividing the prediction into these segments, each with its own correction factors, the system achieves high accuracy while keeping each individual calculation step manageable and interpretable.
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
The solution allows for more accurate prediction and prevention of low-speed pre-ignition by considering fuel adherence and recirculation gas ratios, thereby enhancing engine performance and reducing the risk of pre-ignition events.
Implementation Method 1
An exhaust gas recirculation apparatus recirculates part of exhaust gas that is discharged from a combustion chamber of an engine toward the atmosphere through an exhaust passage, into an intake passage, whereby the combustion temperature in the combustion chamber is lowered, and emission of nitrogen oxides (NOx) contained in the exhaust gas is suppressed.
Implementation Method 2
The recirculation gas which swirls in the combustion chamber along the inner peripheral wall of the cylinder forms an annular recirculation gas layer in a portion near the inner peripheral wall.
Implementation Method 3
an auto-ignition index calculating unit that is configured to calculate, based on a cylinder temperature and a cylinder pressure in a combustion chamber, an auto-ignition index which indicates easiness of occurrence of auto-ignition of fuel at a crank angle before an ignition timing in a compression stroke
Implementation Method 4
a first correction coefficient calculating unit that is configured to calculate, based on an amount of fuel adhering to a wall surface of the combustion chamber at the crank angle, a wall-adhering fuel correction coefficient for correcting the auto-ignition index
Implementation Method 5
a low-speed pre-ignition predicting unit that is configured to predict, based on the auto-ignition index and the wall-adhering fuel correction coefficient, occurrence of low-speed pre-ignition
Data Source
AI summary
A controlling apparatus for an engine, includes: an auto-ignition index calculating unit that is configured to calculate, based on a cylinder temperature and a cylinder pressure in a combustion chamber, an auto-ignition index which indicates easiness of occurrence of auto-ignition of fuel at a crank angle before an ignition timing in a compression stroke; a first correction coefficient calculating unit that is configured to calculate, based on an amount of fuel adhering to a wall surface of the combustion chamber at the crank angle, a wall-adhering fuel correction coefficient for correcting the auto-ignition index; and a low-speed pre-ignition predicting unit that is configured to predict, based on the auto-ignition index and the wall-adhering fuel correction coefficient, occurrence of low-speed pre-ignition.