Engine Combustion Mode Transition Control via Variable Valve Actuation
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Solution Overview
Problem
Internal combustion engines, particularly those operating in auto-ignition combustion mode, face challenges in smoothly transitioning between spark-ignition and auto-ignition combustion modes to maintain robust combustion, low emissions, and optimal heat release rates, requiring precise control of airflow and valve operations.
Innovation Solution
A method and control scheme that determines preferred combustion modes by monitoring mass airflow, intake manifold pressure, and cylinder volume, adjusting the controllable throttle valve and variable valve actuation system to manage transitions between combustion modes, ensuring continuous engine output torque and preventing misfires or partial burns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the engine transitions from spark-ignition to auto-ignition combustion mode, then emissions are reduced and fuel efficiency is improved, but combustion stability deteriorates and misfires occur during transition
Solution Approach 1:
The system dynamically adjusts valve timing and throttle position in real-time during combustion mode transitions. The variable valve actuation system modifies intake and exhaust valve events adaptively, while the throttle valve position is continuously adjusted to maintain stable combustion conditions as the engine transitions between spark-ignition and auto-ignition modes, preventing misfires and ensuring combustion stability throughout the transition process
Solution Approach 2:
The control system changes multiple operating parameters simultaneously during mode transitions, including intake manifold pressure, mass airflow, valve timing duration, and throttle position. By coordinating these parameter changes, the system maintains optimal combustion conditions while transitioning between combustion modes, reducing emissions while preserving combustion stability
2Speed
If the throttle valve position is adjusted rapidly during mode transition, then response time is reduced, but combustion stability deteriorates due to abrupt airflow changes
Solution Approach 1:
The system employs dynamic, coordinated adjustment of multiple components during mode transitions. The throttle valve, intake valves, and exhaust valves are all adjusted in a coordinated manner with timing and duration optimized for each specific transition scenario. This dynamic coordination allows rapid response while maintaining combustion stability by ensuring airflow changes are appropriately matched to the transitioning combustion mode requirements
Solution Approach 2:
The variable valve actuation system performs preliminary adjustments to valve timing and duration before and during throttle valve adjustment. By pre-positioning the valves and preparing the combustion chamber conditions in advance, the system enables faster throttle response while maintaining combustion stability, as the combustion chamber is already prepared to accommodate the incoming airflow changes
3Object-generated harmful factors
If valve timing is optimized for auto-ignition mode, then emissions are reduced, but the engine cannot maintain robust combustion in spark-ignition mode
Solution Approach 1:
The variable valve actuation system provides multi-functionality by enabling the same valve train to optimize combustion for both spark-ignition and auto-ignition modes. The system can adjust intake and exhaust valve timing and duration to match the specific requirements of each combustion mode, allowing the engine to achieve low emissions in auto-ignition mode while maintaining robust combustion in spark-ignition mode, and smoothly transition between modes as needed
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 combustion modes, maintaining robust and stable combustion, low emissions, and optimal heat release rates, while preventing engine operation from becoming too lean or rich, thus ensuring continuous engine performance.
Implementation Method 1
exhaust recompression
Implementation Method 2
auto-ignition combustion mode
Implementation Method 3
heating to the cylinder charge so that auto-ignition during the compression stroke
Data Source
AI summary
A method to control operation of an engine during a transition from a first to a second combustion mode is provided. The engine includes a controllable throttle valve, a variable valve actuation system for controlling openings and closings of intake and exhaust valves, and, an intake and an exhaust. Mass airflow, intake manifold pressure, and cylinder volume to operate the engine in the second combustion mode and meet an operator torque request are determined. Current states for mass airflow, intake manifold pressure, and cylinder volume are determined. An opening position of the controllable throttle valve and the openings and the closings of the intake and exhaust valves are controlled during the transition to the second combustion mode based upon differences between the current states for mass airflow, intake manifold pressure, and cylinder volume, and, the mass airflow, the intake manifold pressure, and the cylinder volume.