Lean Burn Engine Cylinder Group Mode Transition Control
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Solution Overview
Problem
Existing engine control strategies face issues with sensor degradation, leading to un-matched air and fuel amounts in cylinders, resulting in errors in engine torque estimation, increased emissions, and reduced drivability, particularly when transitioning between operating modes.
Innovation Solution
A multi-cylinder engine system with separate cylinder groups operating in different modes, where one group pumps air without fuel injection, allowing for a slower transition out of degraded modes to match air and fuel amounts, reducing errors and emissions by providing additional airflow to meet torque demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine transitions out of a degraded mode immediately upon sensor degradation detection, then the control strategy avoids using degraded sensors, but un-matched air and fuel amounts occur in cylinders causing errors in engine torque estimation and control
Solution Approach 1:
The system performs preliminary actions by increasing airflow to both cylinder groups before fuel injection is reactivated to the cut-out group. This preparatory airflow increase ensures that when fuel injection resumes, the air-fuel mixture is properly balanced, preventing un-matched conditions that would cause torque estimation errors.
Solution Approach 2:
The transition process is made dynamic and adaptive rather than instantaneous. The system adjusts airflow and fuel injection timing based on real-time conditions, allowing the engine to smoothly transition between operating modes while maintaining proper air-fuel matching throughout the transition period.
2Reliability
If the engine transitions out of a degraded mode immediately upon sensor degradation detection, then the control strategy avoids using degraded sensors, but increased emissions occur due to un-matched air and fuel amounts
Solution Approach 1:
The system performs preliminary airflow increase to both cylinder groups before reactivating fuel injection. This preliminary action ensures proper air-fuel mixture preparation, preventing incomplete combustion and reducing harmful emissions that would result from un-matched air and fuel amounts during mode transition.
3Reliability
If the engine transitions out of a degraded mode immediately upon sensor degradation detection, then the control strategy avoids using degraded sensors, but reduced drivability occurs as fuel may be provided before excess air is reduced
Solution Approach 1:
The system performs preliminary airflow management before fuel injection reactivation. By adjusting airflow to appropriate levels first, the system ensures that when fuel injection resumes to the cut-out cylinder group, the air-fuel mixture is properly balanced, preventing drivability issues caused by un-matched conditions.
Solution Approach 2:
The transition is made dynamic and adaptive, adjusting airflow and fuel injection timing based on real-time engine conditions. This dynamic approach maintains smooth engine operation and drivability throughout the transition period, preventing the harsh effects of sudden un-matched air-fuel conditions.
4Use of energy by moving object
If the engine operates in a mode with one cylinder group pumping air without fuel injection to meet torque demand, then fuel efficiency is improved, but upon mode transition fuel injection is reactivated causing un-matched air and fuel amounts
Solution Approach 1:
When transitioning from the fuel-cut mode back to full fuel injection mode, the system performs preliminary airflow adjustment to both cylinder groups before reactivating fuel injection. This ensures that the air-fuel mixture is properly balanced from the start of fuel injection, maintaining precise air-fuel matching and avoiding the un-matched conditions that would occur with immediate full fuel injection.
Data Source
AI summary
A multi-cylinder group engine system operable in at least a first mode and a second mode, where in the first mode a first and second cylinder group combust air and fuel with a lean air-fuel ratio, and where in the second mode at least one of the first and second cylinder groups combusts air and fuel and the other one of the first and second cylinder groups pumps air without injected fuel, the engine system comprising of a fuel injection activity sensor coupled to each cylinder in the first and second cylinder groups; a exhaust gas sensor disposed in an exhaust passage to measure air fuel exhausted from the engine; and a controller configured to transition out of the first mode responsive to detection of exhaust gas sensor degradation and to transition out of the second mode responsive to detection of fuel injection sensor degradation. In one example, the transition out of the second mode may be slower than the transition out of the first mode in response to the respective degradation.