Engine Control Device Combustion Stability During Mode Switching
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Solution Overview
Problem
Combustion stability deteriorates during mode switching in internal combustion engines due to delays in air and fuel control system changes, particularly in transient states, leading to suboptimal fuel consumption and exhaust purification performance.
Innovation Solution
Implementing a delay in switching between compression stroke and intake stroke injections based on the magnitude of transient state changes, synchronized with air control system delays, to ensure stable air-fuel ratios and flow control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the combustion mode is switched from stratified lean combustion to homogeneous lean combustion, then the operation performance is improved, but the combustion stability deteriorates due to control system delays
Solution Approach 1:
The air control system is switched before the fuel injection system when transitioning from stratified lean combustion to homogeneous lean combustion. This preliminary action ensures that the air flow pattern is established first, allowing the fuel injection timing to be synchronized with the actual air flow conditions, thereby maintaining combustion stability while achieving the desired operation performance.
2Speed
If simultaneous switching of air control and fuel injection is performed, then the response speed is improved, but the air-fuel ratio control accuracy deteriorates
Solution Approach 1:
The switching process is segmented into two sequential steps: first switching the air control system, then switching the fuel injection system after a predetermined delay. This segmentation allows each subsystem to be controlled independently according to its specific response characteristics, ensuring both fast overall response and accurate air-fuel ratio control.
Solution Approach 2:
The air control system is switched in advance before the fuel injection system. This preliminary action accounts for the different response times of the two systems, ensuring that the air flow pattern is established before fuel injection begins, thereby maintaining precise air-fuel ratio control while achieving rapid mode transition.
3Speed
If the tumble control valve opening degree is changed rapidly, then the mode switching speed is improved, but the flow delay increases
Solution Approach 1:
The air control system is switched before the fuel injection system to compensate for the flow delay caused by rapid tumble control valve movement. This preliminary action ensures that the air flow has sufficient time to adjust to the new opening degree before fuel injection begins, reducing the negative impact of flow delay while maintaining fast mode switching.
Data Source
AI summary
In an internal combustion engine which performs a homogeneous lean combustion mode and a stratified lean combustion mode, there is provided a new internal combustion engine control device capable of obtaining a stable combustion state by decreasing influences of delay of an air flow and a degree of change of a transient state and smoothly performing switching between the homogeneous lean combustion mode and the stratified lean combustion mode. Accordingly, in the present invention, when switching between the stratified lean mode in which a compression stroke injection is performed by a direct injection injector 7 and the homogeneous lean combustion mode in which an intake stroke injection is performed by the direct injection injector 7 is performed, a predetermined delay time Δt is provided from at least a switching operation of a tumble control valve 6, a switching operation between the compression stroke injection and the intake stroke injection is performed, and the delay time Δt is set so as to correspond to a magnitude of the degree of change ΔL of the transient state. A switching timing between the compression stroke injection and the intake stroke injection is controlled according to the flow delay of an air control system such as the tumble control valve 6 and the degree of change ΔL of the transient state, and thus, it is possible to improve combustion stability in a combustion chamber.