Direct-Injection Engine Control for Combustion Mode Transition
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Solution Overview
Problem
Direct fuel injection engines face challenges in smoothly switching from homogenous to stratified combustion modes without compromising combustion stability, leading to potential instability or increased NOx emissions.
Innovation Solution
A control method that manages fuel injection in direct fuel injection engines by performing homogenous combustion at low loads and stratified combustion at high loads, using multiple fuel injections to distribute fuel unevenly near the ignition plug, with a larger initial injection followed by a decrease in the second injection amount to maintain stability and control NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the injection amount of the second injection operation is increased to avoid unstable combustion during switching from homogenous to stratified combustion, then combustion stability is improved, but NOx emission increases and combustion becomes excessively steep
Solution Approach 1:
The patent applies dynamics by making the injection amount of the second injection operation changeable over time during the switching process. The control device increases the injection amount temporarily during the transition phase to ensure combustion stability, then gradually reduces it to the target amount. This dynamic adjustment allows the system to adapt to changing operational conditions without permanently increasing NOx emissions or creating excessively steep combustion.
Solution Approach 2:
The patent applies preliminary action by temporarily increasing the injection amount of the second injection operation before the switching is complete. This preliminary increase in fuel injection ensures that sufficient fuel is available during the transition from homogenous to stratified combustion, preventing unstable combustion. After the switching is established, the injection amount is reduced to the appropriate level, avoiding permanent increases in NOx emissions.
2Object-generated harmful factors
If the injection amount of the second injection operation is limited to a small amount to suppress NOx emission, then NOx emission is reduced, but combustion becomes unstable during switching from homogenous to stratified combustion
Solution Approach 1:
The control device dynamically adjusts the injection amount of the second injection operation based on the operational phase. During the switching phase from homogenous to stratified combustion, the injection amount is temporarily increased to ensure stable combustion. Once the switching is complete and the engine is operating in stratified combustion mode, the injection amount is reduced to a small amount to suppress NOx emissions. This dynamic control resolves the contradiction by applying different injection strategies at different phases.
Solution Approach 2:
The patent applies preliminary action by temporarily increasing the second injection amount during the switching phase to ensure combustion stability. This preliminary increase provides sufficient fuel during the critical transition period. After the switching is established, the injection amount is reduced to the target small amount for normal stratified combustion operation, thereby suppressing NOx emissions while maintaining stability during the transition.
3Loss of energy
If homogenous combustion is switched to stratified combustion in response to increase in engine load, then fuel efficiency is improved, but combustion stability is compromised during the switching transition
Solution Approach 1:
The control device applies dynamics by dynamically adjusting the injection amount of the second injection operation during the switching process. When switching from homogenous to stratified combustion in response to increased engine load, the injection amount is temporarily increased to ensure stable combustion during the transition. After the switching is complete and fuel efficiency benefits are realized, the injection amount is reduced to the appropriate level for sustained stable operation.
Solution Approach 2:
The patent applies preliminary action by temporarily increasing the second injection amount during the switching transition from homogenous to stratified combustion. This preliminary increase ensures that sufficient fuel is available during the critical transition phase when combustion stability is most vulnerable. Once the switching is established and fuel efficiency is improved, the injection amount is reduced to the target amount, maintaining both stability and efficiency.
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 stable switching between combustion modes, improving heat efficiency and reducing NOx emissions by optimizing fuel distribution and injection timing, thereby enhancing overall engine performance and reducing fuel consumption.
Implementation Method 1
a fuel is dispersed in a cylinder by a first injection operation of a fuel injection valve and the fuel is unevenly distributed in a vicinity of an ignition plug by a second injection operation of the fuel injection valve
Implementation Method 2
In a first region on a low load side of an operation region of an engine, homogenous combustion is performed, while, in a second region of the operation region on a load side higher than the first region, stratified combustion is performed
Data Source
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AI summary
In the present invention, among the operating regions of an engine, homogeneous combustion is carried out in a first region on a low-load side, whereas in a second region in which the load is higher than in the first region, stratified combustion is carried out wherein fuel is dispersed in a cylinder by means of a first injection operation and fuel is concentrated in the vicinity of a spark plug by means of a second injection operation. In a region transition in which the operating state of the engine has transitioned from the first region to the second region, a transition control based on the stratified combustion is carried out. In the transition control, a greater amount of fuel than a target amount for the second injection operation in the second region is injected by means of the second injection operation, after which the injection amount in the second injection operation is reduced toward the target amount.