Engine Intake Gas Composition Control for Combustion Mode Transitions
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining robust combustion modes during transient phases due to deviations in intake gas composition, leading to increased NOx emissions, combustion noise, and torque loss when transitioning between low temperature combustion (LTC) and standard diesel combustion modes.
Innovation Solution
A system and method that adjusts the fuel quantity and injection timing based on the difference between desired and actual proportions of combusted gas in the engine intake, utilizing an electronic control unit (ECU) to command adjustments in fuel injectors and EGR valve, while incorporating pilot injections during transitions between combustion modes, and using sensors for real-time intake gas composition estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If new combustion modes like low temperature combustion (LTC) are used to reduce exhaust emissions, then emissions are reduced, but combustion robustness deteriorates during transient phases
Solution Approach 1:
The system uses feedback control by continuously monitoring the actual proportion of combusted gas in the intake (via oxygen sensors and other engine sensors) and comparing it to the desired proportion. The ECU adjusts fuel quantity and injection timing based on the difference between actual and desired FMAN values, enabling the system to maintain combustion stability during transient phases while operating in LTC mode.
Solution Approach 2:
The system dynamically adjusts fuel injection parameters (quantity and timing) in real-time during transient operating phases. The ECU modifies injection timing and fuel quantity based on changing engine conditions and the difference between desired and actual FMAN, allowing the combustion mode to adapt to transient conditions while maintaining robustness.
2Speed
If EGR rate and intake pressure are changed rapidly to accomplish transitions, then transition speed is improved, but combustion stability deteriorates due to deviations in intake gas composition
Solution Approach 1:
The system monitors actual FMAN during transitions and provides feedback to the ECU, which adjusts fuel injection parameters to compensate for deviations caused by rapid EGR rate and intake pressure changes. This feedback mechanism maintains combustion stability even during fast transitions between combustion modes.
Solution Approach 2:
The system changes injection parameters (fuel quantity and timing) in response to changing operating conditions during transitions. By adjusting these parameters based on the difference between desired and actual FMAN, the system compensates for the effects of rapid EGR and pressure changes, maintaining stable combustion throughout the transition.
3Object-generated harmful factors
If actual FMAN is less than desired FMAN, then NOx emissions and combustion noise increase, but if actual FMAN exceeds desired FMAN, then combustion becomes unstable leading to torque loss and increased fuel consumption
Solution Approach 1:
The system uses feedback control to maintain actual FMAN close to the desired value. The ECU continuously adjusts fuel quantity and injection timing based on the difference between actual and desired FMAN, preventing both excessive FMAN (which causes instability and torque loss) and insufficient FMAN (which causes high NOx and noise), thereby optimizing both emissions and performance.
Solution Approach 2:
The system adjusts injection parameters (fuel quantity and timing) to maintain optimal FMAN levels. By changing these parameters in response to deviations from desired FMAN, the system prevents combustion instability and torque loss while avoiding excessive NOx emissions and combustion noise.
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
Enables smooth transitions between LTC and standard diesel combustion modes, maintaining desired torque response, reducing emissions and noise, and ensuring high fuel efficiency without compromising performance or compliance.
Implementation Method 1
The actual composition of intake gas is based on a signal from an oxygen sensor coupled to the engine intake
Implementation Method 2
The determined quantity of fuel is commanded to a fuel injector coupled to a cylinder of the engine. The determined injection timing is commanded to the fuel injector
Implementation Method 3
an EGR valve disposed in the EGR duct, and an oxygen sensor coupled to the engine intake at a location downstream of where the EGR duct is coupled to the engine intake
Implementation Method 4
The ECU estimates the actual intake gas composition based on at least one of mass air flow into the engine, intake manifold absolute pressure, temperature of the intake gases downstream of the addition of EGR into the intake gases, engine rpm, and a signal from an oxygen sensor coupled to an engine exhaust
Data Source
AI summary
A system and method are disclosed for controlling an internal combustion engine in which actual concentration of combusted gas in the intake is compared with desired concentration of combusted gas in the intake. When a difference is detected, at least one of start of injection timing and quantity of fuel injected is adjusted in accordance with the difference. The actual concentration of combusted gas in the intake is estimated based on engine sensors such as an oxygen sensor coupled to an engine intake. The adjustment of injection timing and/or quantity of fuel is performed, according to some embodiments, during a transition between a low temperature combustion mode and a standard diesel combustion mode.