Fuel Injector Valve-Closing Time Detection via Comparator Thresholds
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Solution Overview
Problem
Existing fuel injection control apparatuses require A/D conversion and differentiation of coil current to detect valve-closing time, increasing processing load and needing an additional A/D conversion channel.
Innovation Solution
A fuel injection control apparatus that detects valve-closing time without A/D conversion or differentiation of coil current by comparing the coil current with multiple threshold values and determining the valve-closing time based on detected times using comparators and a microcomputer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If A/D conversion and differentiation of coil current are used to detect valve-closing time, then measurement precision is improved, but device complexity and processing load increase
Solution Approach 1:
The patent replaces the conventional A/D conversion and differentiation processing with a comparator-based voltage comparison system. Instead of converting coil current to digital signals and performing mathematical differentiation, the system uses a current-voltage conversion circuit followed by comparators that directly compare the converted voltage with threshold values, substituting complex digital processing with simpler analog comparison operations.
Solution Approach 2:
The patent changes the detection parameter from coil current to converted voltage signal. By introducing a current-voltage conversion circuit, the system transforms the measurement parameter from current (requiring A/D conversion) to voltage (可直接 compared by analog comparators), fundamentally changing the detection approach to eliminate digital conversion requirements.
2Measurement precision
If A/D conversion is used to detect valve-closing time, then measurement precision is improved, but the number of A/D conversion channels increases
Solution Approach 1:
The patent eliminates the need for A/D conversion channels by replacing the entire A/D conversion process with an analog comparator-based system. The current-voltage conversion circuit followed by voltage-threshold comparison provides a direct analog detection method that achieves the same measurement precision without requiring any digital conversion infrastructure.
3Measurement precision
If differentiation of coil current is performed to detect valve-closing time, then measurement precision is improved, but processing load increases
Solution Approach 1:
The patent replaces the computationally intensive differentiation operation with a simple voltage threshold comparison. Instead of calculating the derivative of the coil current signal through digital processing, the system uses the physical property that voltage thresholds are naturally crossed at specific current levels, allowing direct detection without mathematical operations.
Solution Approach 2:
The patent makes the detection system self-service by using the inherent electrical characteristics of the coil circuit. The voltage conversion and threshold comparison automatically provide detection signals without requiring external processing power, eliminating the need for high-performance processors to perform differentiation calculations.
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 allows for accurate detection of valve-closing time without increasing processing load or requiring additional A/D conversion channels, enhancing the efficiency of fuel injection control.
Implementation Method 1
an electromagnetic solenoid-type injector is used. This injector is driven to open its valve when its coil is powered by electric current.
Implementation Method 2
The detection part detects a valve-closing time of the injector based on the coil current, which decreases from the end time of the drive period.
Data Source
AI summary
In a fuel injection control apparatus, an injector is driven to open its valve by supplying a coil of the injector with a current during a high-level period of a power supply command signal outputted from a microcomputer. A valve-closing time of the injector is detected based on a coil current, which decreases from a fall time of the power supply command signal. By comparing the coil current with plural equally-divided comparison threshold values by comparators, times are detected when the coil current decreases to the comparison threshold values, respectively. The valve-closing time is detected based on time differences among the detected times.