Fuel Injection Timing Control for Compression Ignition Engines
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Solution Overview
Problem
Conventional internal combustion engine control systems fail to stabilize combustion and reduce combustion noise due to fluctuations in in-cylinder temperature and pressure, leading to increased COVn and dP/dθmax, which can cause engine instability and damage.
Innovation Solution
An internal combustion engine control apparatus with a variable valve mechanism and electronic control unit that adjusts the negative valve overlap period and fuel injection timing to optimize fuel injection within specific fuel injection starting periods, ensuring the in-cylinder temperature meets threshold values to stabilize combustion and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel injection timing is not controlled within specific periods during NVO, then the system structure remains simple, but combustion stability deteriorates and COVn increases
Solution Approach 1:
The invention changes the timing parameter of fuel injection by defining specific fuel injection starting periods (first period including exhaust TDC, second period excluding exhaust TDC) based on the NVO starting timing. The ECU controls fuel injection to occur within these predetermined periods, thereby stabilizing combustion and reducing COVn without requiring complex additional hardware.
2Object-affected harmful factors
If fuel injection timing is not optimized according to NVO starting timing, then the control system remains simple, but combustion noise increases and dP/dθmax becomes too high
Solution Approach 1:
The invention optimizes the timing parameter of fuel injection by establishing two distinct fuel injection starting periods based on NVO characteristics. The first period includes exhaust TDC for stable combustion, while the second period excludes exhaust TDC to reduce combustion noise and dP/dθmax. This parameter-based control reduces harmful effects without adding device complexity.
3Manufacturing precision
If the NVO period is extended to improve fuel quality, then fuel injection effectiveness improves, but cooling loss increases and gasoline mileage deteriorates
Solution Approach 1:
The invention optimizes the timing parameter of fuel injection by controlling injection to occur within specific periods during the NVO period. This ensures fuel is injected when in-cylinder temperature and pressure are appropriate for vaporization and mixing, improving fuel quality and ignition performance without requiring an excessively prolonged NVO period, thereby minimizing cooling losses.
Solution Approach 2:
The invention performs preliminary action by controlling fuel injection to occur during the NVO period before the power stroke begins. This allows fuel to be injected and begin vaporizing during the compression phase when temperatures are rising, ensuring proper fuel-air mixture formation before combustion starts, which improves combustion efficiency without extending the NVO period.
4Productivity
If fuel injection timing varies without control, then the system operates simply, but pump loss fluctuates and engine efficiency decreases
Solution Approach 1:
The invention controls the timing parameter of fuel injection by defining specific fuel injection starting periods based on NVO characteristics. This stabilizes pump loss and improves engine efficiency by ensuring fuel is injected at optimal times when in-cylinder conditions are favorable, without requiring complex additional control mechanisms beyond the ECU.
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
The solution effectively stabilizes combustion, reduces COVn and dP/dθmax, preventing engine instability and noise, and optimizing fuel injection timing to maintain acceptable engine performance.
Implementation Method 1
the quality of the fuel is improved because fuel injection is implemented during an NVO period so that the fuel is exposed to a high temperature
Implementation Method 2
A compression self-ignition internal combustion engine utilizes exhaust gas heat in order to secure ignition of a fuel-air mixture
Implementation Method 3
the compression ratio is raised so that a fuel-air mixture is ignited by itself through compression
Data Source
AI summary
When the starting timing of a negative valve overlapping (NVO) period exists at the delayed-angle side of the starting timing of a first NVO period, fuel injection into a cylinder is not started; when the starting timing of an NVO period exists between the starting timing of the first NVO period and the starting timing of the second NVO period, fuel injection into the cylinder is started at a given timing that includes the exhaust top dead center; when the starting timing of an NVO period exists between the starting timing of the second NVO period and the starting timing of the third NVO period, fuel injection into the cylinder is started at a given timing that does not include the exhaust top dead center, and that exists at both the advanced-angle and delayed-angle sides of the exhaust top dead center.