Engine Start Control Adjusting Fuel Injection for Piston Position
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Solution Overview
Problem
Existing engine start control systems face issues with misfires and unstable torque generation due to insufficient air-fuel mixture introduction during engine restarts, particularly when the piston stop position is not optimal, leading to prolonged engine starting times and poor emissions.
Innovation Solution
An engine start control apparatus that detects the piston stop position and adjusts fuel injection accordingly, varying the amount of fuel injected into the intake port based on the piston position to optimize air-fuel mixture introduction and ignition timing, thereby reducing misfire rates and stabilizing torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fuel is injected into a cylinder stopping in the intake stroke to restart the engine, then the starting time is shortened, but misfire occurs due to insufficient air-fuel mixture introduction
Solution Approach 1:
The system performs preliminary detection of the piston stop position before fuel injection, and pre-calculates the appropriate fuel injection amount based on the detected position. This preliminary action ensures that when fuel is injected for engine restart, the correct amount is delivered to prevent misfire while maintaining short starting time.
Solution Approach 2:
The system changes the fuel injection amount parameter based on the piston stop position. When the piston stops near bottom dead center where intake efficiency is low, the system increases the fuel injection amount to compensate for insufficient air-fuel mixture introduction, thereby preventing misfire while maintaining quick engine restart.
2Speed
If the piston stop position is not optimal, then engine restart is faster, but torque generation becomes unstable
Solution Approach 1:
The system adjusts the fuel injection amount parameter according to the piston stop position detected before engine restart. By increasing fuel injection when the piston stops suboptimally (near bottom dead center), the system stabilizes the air-fuel mixture quality, ensuring stable torque generation even when engine restart occurs at non-ideal speeds.
Solution Approach 2:
The system uses feedback from the piston position detection to dynamically adjust the fuel injection amount. This closed-loop control ensures that regardless of where the piston stops during engine shutdown, the subsequent fuel injection will produce stable combustion and consistent torque output upon engine restart.
3Reliability
If fuel injection amount is increased to prevent misfire, then startability improves, but emission performance deteriorates due to excessive fuel
Solution Approach 1:
The system dynamically changes the fuel injection amount parameter based on the piston stop position. Instead of using a fixed high injection amount, the system calculates the precise fuel quantity needed for each detected piston position, ensuring sufficient fuel for reliable combustion while avoiding excessive fuel injection that would cause poor emission performance.
Solution Approach 2:
The system applies partial fuel injection (exactly the amount needed) rather than excessive fuel injection. By matching the fuel amount to the specific piston position and intake conditions, the system achieves reliable engine start without over-injecting fuel, thereby preventing emission deterioration.
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
This approach improves engine startability, reduces misfire rates, and enhances drivability by ensuring a stable torque output and minimizing emissions during engine restarts.
Implementation Method 1
inject a fuel from a fuel injection unit, which is attached to a specific cylinder stopping in an intake stroke, into an intake port of the specific cylinder
Implementation Method 2
ignite the air-fuel mixture for first combustion in the cylinder stopping in the intake stroke
Data Source
AI summary
In a motor vehicle with idle stop function, upon satisfaction of preset engine restart conditions (step S205), automatic engine restart control refers to a preset map representing a variation in amount of fuel Q1, which is to be initially injected into a cylinder Cyin stopping in an intake stroke, against the piston stop position Pin of the cylinder Cyin, and specifies the amount of fuel Q1 corresponding to the detected piston stop position Pin of the cylinder Cyin (step S220). The automatic engine restart control then controls an injector to inject the specified amount of fuel Q1 into an intake port of the cylinder Cyin (step S230). Under the condition that the piston stop position Pin of the cylinder Cyin suggests low gas intake performance, the increased amount of fuel Q1 is injected into the intake port of the cylinder Cyin. This arrangement desirably reduces a misfire rate at the timing of first combustion and thereby improves the startability of an engine. When the amount of fuel Q1 specified at step S220 is equal to zero, the cylinder Cyin is not subject to the first combustion. Such control desirably prevents poor emission.