Fuel Injector Pulse Width Correction for Injection Precision
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Solution Overview
Problem
Existing fuel injection systems in internal combustion engines face challenges in achieving precise and reliable fuel injection due to variations in injector performance over time, leading to unequal fuel quantities and timing between cylinders.
Innovation Solution
A method for controlling fuel injection systems that involves determining a pulse width correction value based on learned hydraulic open times of the injectors, using a map that relates demand fuel quantity to correction values, thereby ensuring efficient and precise fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional reference map based pulse width control is used, then the control system is simple, but injector performance variations over time cause imprecise fuel injection
Solution Approach 1:
The system performs preliminary learning of injector characteristics during engine operation to build correction maps before precise control is needed. The ECU learns the actual pulse widths delivered to each injector and stores this information for future compensation, enabling accurate injection control without complex real-time measurements.
Solution Approach 2:
The system implements feedback by comparing the commanded pulse width with the actual pulse width delivered to the injector. The difference is used to generate correction values that are stored in maps and applied to future injection commands, continuously improving injection precision based on actual injector performance.
2Reliability
If injector specific learning compensation is implemented, then fuel injection precision is improved, but the control method becomes more complex
Solution Approach 1:
The control system performs self-calibration by automatically learning injector characteristics during normal engine operation. The ECU monitors actual pulse widths and generates correction maps without requiring external calibration equipment or manual intervention, making the system self-adjusting and reliable.
Solution Approach 2:
The system changes the control parameter from fixed reference pulse widths to dynamic corrected pulse widths based on learned injector characteristics. The correction maps store adjusted pulse width values that compensate for injector variations, allowing the control system to adapt to changing injector performance over time.
3Manufacturing precision
If periodic calibration is performed, then injector variations are compensated, but engine downtime and complexity increase
Solution Approach 1:
The system performs continuous learning of injector characteristics during normal engine operation rather than requiring periodic shutdowns for calibration. The ECU accumulates data and updates correction maps in real-time, ensuring injection precision is maintained without interrupting engine operation or losing valuable runtime.
Data Source
AI summary
A method of controlling fuel injection in an internal combustion engine having at least one cylinder with an associated fuel injector for performing injector events, wherein for each injector event a drive signal is generated to cause an opening of the fuel injector to spray fuel in accordance with a demand fuel quantity. In a drive mode, the drive signal has a length, PWf, that corresponds to a reference length, PWref, determined from a reference map, MAP-PWref, of demand fuel quantity vs. pulse length, and corrected by a correction value, PWcorr. PWcorr is determined based on a map, MAP-PWcorr, depending on demand fuel quantity, the map MAP-PWcorr being learned during engine runtime and representing a difference between a learned, injector-specific hydraulic open time and a reference hydraulic open time.