Engine Control Apparatus for Stable Combustion
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Solution Overview
Problem
Internal combustion engines face challenges in achieving stable combustion and reducing torque fluctuations, particularly in low-speed and high-load regions, due to inhomogeneous air-fuel mixtures, and require complex control strategies for switching between stratified and homogeneous combustion modes, which complicates fuel efficiency and emission control.
Innovation Solution
A control apparatus that adjusts the fuel injection ratio between in-cylinder and intake manifold injectors based on engine speed and load, using separate maps for warm and cold states to optimize homogeneous combustion and prevent deposit accumulation, while allowing stratified charge combustion during catalyst warm-up to improve emission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If homogeneous combustion is carried out using only the in-cylinder injector, then the control system is simplified and expensive lean NOx catalysts are not required, but the air-fuel mixture becomes inhomogeneous in low-speed and high-load regions causing unstable combustion and large torque fluctuations
Solution Approach 1:
The patent combines both in-cylinder injection and intake port injection systems to operate in homogeneous combustion mode, merging the advantages of direct injection (simplicity, no lean NOx catalyst needed) with intake port injection (superior mixing at low speeds and high loads) to achieve stable combustion without requiring complex stratified charge control
2Productivity
If stratified charge combustion and homogeneous combustion are switched based on operation state, then combustion efficiency is optimized across different conditions, but the control strategy becomes complex requiring separate control programs for each combustion mode
Solution Approach 1:
The patent makes the homogeneous combustion system universal by using both injection mechanisms together to achieve homogeneous combustion across all operation states, eliminating the need for separate control programs for different combustion modes while maintaining optimized combustion efficiency
3Reliability
If the fuel injection ratio between in-cylinder and intake manifold injectors is increased in high-speed regions, then homogeneous combustion is maintained, but torque fluctuations increase in low-speed and high-load regions
Solution Approach 1:
The patent dynamically adjusts the fuel injection ratio between in-cylinder and intake manifold injectors based on engine operating conditions (speed and load), using higher intake port injection ratios at low speeds and high loads to improve mixing and reduce torque fluctuations, while using higher in-cylinder injection ratios at high speeds to maintain homogeneous combustion
Data Source
AI summary
An engine ECU executes a program including the step of detecting an engine coolant temperature (THW), the step of selecting a map for a warm state as the map for calculating a fuel injection ratio (or a DI ratio) r when the engine coolant temperature (THW) is equal to or higher than a temperature threshold value (THW(TH)) (YES in S110), the step of selecting a map for a cold state as the map for calculating the fuel injection ratio (or the DI ratio) r when the engine coolant temperature (THW) is lower than the temperature threshold value (THW(TH)) (NO in S110), and the step of calculating the fuel injection ratio between the in-cylinder injector and the intake manifold injector (or the DI ratio) r based on the engine speed, load factor, and the selected map.