Fuel Injection Controller Current Waveform Detection
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Solution Overview
Problem
Existing fuel injection controllers face challenges in accurately detecting the characteristics of electromagnetic-type fuel injectors due to the short duration of the injector current waveform, which limits detection accuracy and requires high-speed and costly A/D converters.
Innovation Solution
A fuel injection controller with a downstream switching element, refluxing portion, arc extinguishing portion, and drive control portion that prolongs the decreasing period of the injector current by delaying the switching off of the downstream switching element, allowing for more accurate detection of the injector current waveform without the need for high-speed A/D conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the A/D conversion interval is shortened to improve detection accuracy, then detection accuracy improves, but high-speed A/D converter is required which increases cost
Solution Approach 1:
The patent dynamically controls the switching element's turn-off timing based on the injector current waveform characteristics. By delaying the switching element's turn-off until the current decreases to a predetermined level, the system adapts the measurement duration to the actual waveform properties, allowing accurate detection without requiring high-speed A/D converters continuously.
Solution Approach 2:
The patent changes the parameter of switching element turn-off timing from fixed to variable based on current waveform characteristics. By adjusting when the switching element turns off according to the detected current decay rate, the system optimizes the measurement window to capture accurate waveform information while using standard-speed A/D converters.
2Measurement precision
If the downstream switching element is switched off immediately to terminate energization, then energization control precision improves, but the injector current waveform duration becomes too short for accurate detection
Solution Approach 1:
The patent performs preliminary detection of the injector current waveform characteristics before finalizing the switching element turn-off timing. By detecting the current decay characteristics in advance and using this information to determine when to turn off the switching element, the system ensures both accurate waveform capture and proper energization termination.
Solution Approach 2:
The patent implements feedback control where the switching element's turn-off timing is adjusted based on real-time detection of the injector current waveform. The system continuously monitors the current decay and uses this feedback to dynamically determine the optimal turn-off moment, ensuring sufficient waveform duration for detection while maintaining control precision.
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
Improves the detection accuracy of the fuel injector characteristics by prolonging the injector current waveform, reducing the necessity for high-speed A/D converters and thereby lowering costs while maintaining accurate characterization.
Implementation Method 1
a refluxing portion for refluxing the electric current from a downstream of the downstream switching element to an upstream of the coil when the electric-power supplying portion switches from the power applying condition to the non-power applying condition while the downstream switching element is ON
Implementation Method 2
an arc extinguishing portion for extinguishing a counter electromotive force generated in the coil when the electric-power supplying portion switches from the power applying condition to the non-power applying condition and when the downstream switching element is turned OFF from ON
Data Source
AI summary
A fuel injection controller includes a transistor downstream of a coil of a fuel injector, two transistors applying a source voltage to an upstream of the coil, a diode refluxing an electric current to the coil from a ground, and a Zener diode provided to promptly consume the counter electromotive force generated in the coil when one of the transistors is turned OFF and the transistor is turned OFF, after an injector-drive-period of the fuel injector is terminated. When a microcomputer measures an injector current “I” decreasing from a time of the termination of an injector-drive-period, a drive control circuit delays an OFF time of the transistor relative to a time of a termination of an injector-drive-period, whereby the injector current “I” decreases gradually.