Engine Control Device Fuel Injection Pulsation Management
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Solution Overview
Problem
In high engine load conditions, the existing methods for calculating fuel injection amounts in spark ignition internal combustion engines face challenges due to intake air pulsation, leading to decreased controllability of the air-fuel ratio and increased particulate number (PN) emissions, especially at low temperatures.
Innovation Solution
An engine control device that dynamically selects between two fuel injection methods based on the intake air pulsation rate, using a processor to switch between a method based on air flow sensor output and one based on throttle opening degree, with adjusted pulsation rate threshold values correlated with engine temperature and torque conditions, and includes torque increase rate limiting processing to maintain optimal air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first calculation method using air flow sensor output is used, then the intake air amount can be acquired with high accuracy in transient operating conditions, but the output of the air flow sensor is easily pulsated in high engine load conditions leading to decreased air-fuel ratio controllability
Solution Approach 1:
The patent dynamically switches between the first calculation method (using air flow sensor) and the second calculation method (using throttle opening degree and engine speed) based on detected operating conditions. The ECU determines whether to use air flow sensor data or alternative calculation based on engine load conditions, making the system adaptive rather than static.
Solution Approach 2:
The patent changes the parameter used for intake air amount calculation based on operating conditions. When engine load is high and air flow sensor output becomes pulsated, the system switches to using throttle opening degree and engine speed parameters instead, thereby maintaining calculation accuracy under varying conditions.
2Measurement precision
If the first calculation method is used under high load conditions at low temperatures, then the intake air amount can be detected directly, but the particulate number PN increases when the air-fuel ratio fluctuates to the rich side
Solution Approach 1:
The patent incorporates feedback from temperature sensors and air flow sensors to monitor operating conditions. When low temperature and high load conditions are detected, the system receives feedback about these conditions and switches to the second calculation method to prevent rich air-fuel ratio fluctuations that would increase particulate emissions.
Solution Approach 2:
The patent takes preliminary action by switching to the second calculation method before particulate emissions can increase. By detecting low temperature and high load conditions in advance, the system preemptively avoids using air flow sensor data that would lead to inaccurate intake air amount calculation and subsequent rich air-fuel ratio conditions.
Data Source
AI summary
An engine control device includes a processor configured to execute a fuel injection control including: a first fuel injection processing for injecting an amount of fuel according to a first intake air amount based on an intake air flow rate detected by an air flow sensor; and a second fuel injection processing for injecting an amount of fuel according to a second intake air amount based on a throttle opening degree detected by a throttle position sensor. The processor selects the first fuel injection processing when a pulsation rate of the intake air flow rate is equal to or lower than a pulsation rate threshold value, and selects the second fuel injection processing when the pulsation rate is higher than the pulsation rate threshold value. The pulsation rate threshold value is smaller when a temperature correlation value is low than when the temperature correlation value is high.