Fuel Injection Valve Voltage Inflection Detection
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Solution Overview
Problem
Existing fuel injection control systems for internal combustion engines face challenges in accurately correcting variations in injection quantity due to variations in lift amount in the partial lift region, leading to degraded exhaust emission and drivability.
Innovation Solution
A fuel injection control system that includes an injection control means for full and partial lift injections, filtered-voltage acquisition means using low-pass filters to remove noise, a difference calculation means to determine voltage inflection time, and an injection pulse correction means that corrects the injection pulse based on the voltage inflection time, utilizing a stored relationship between voltage inflection time and injection quantity to set the required injection pulse width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the unfiltered drive voltage UM is compared to the filtered reference voltage UR to detect armature position, then the detection method is simple, but the detection accuracy is low due to noise influence and possible non-existence of intersection
Solution Approach 1:
The patent applies preliminary action by filtering the drive voltage signal before comparison. Specifically, it filters the unfiltered drive voltage UM through a low-pass filter to obtain a filtered drive voltage, then compares this filtered signal with the reference voltage UR. This preliminary filtering action removes noise components and ensures the existence of a clear intersection point, thereby improving armature position detection accuracy without significantly increasing system complexity
Solution Approach 2:
The patent introduces an intermediary element - the low-pass filter - between the unfiltered drive voltage UM and the reference voltage UR. This filter acts as a mediator that processes the noisy signal, removing high-frequency noise components while preserving the essential signal characteristics needed for accurate armature position detection through intersection analysis
2Duration of action of moving object
If the lift amount of the valve element is allowed to vary greatly in the partial lift region, then the injection pulse width can be reduced, but the injection quantity varies greatly leading to degraded exhaust emission and drivability
Solution Approach 1:
The patent applies feedback by detecting the actual armature position through voltage intersection analysis and using this information to correct the injection quantity. The system monitors the lift amount variation in real-time and adjusts the injection pulse width accordingly, creating a closed-loop control system that maintains precise injection quantity control even in the partial lift region where lift amount varies
Solution Approach 2:
The patent changes the parameter being controlled from direct lift amount control to armature position-based injection quantity correction. By detecting armature position through voltage intersection and using this parameter to correct injection quantity, the system achieves precise control without requiring constant lift amount maintenance, thereby improving injection precision while allowing flexible pulse width adjustment
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 accurately corrects the variation in injection quantity, improving control accuracy in the partial lift region by effectively accounting for the valve-closing timing and lift amount variations, thereby enhancing exhaust emission and drivability.
Implementation Method 1
acquires a first filtered voltage being a terminal voltage of the fuel injection valve filtered by a first low-pass filter having a first frequency as a cutoff frequency, the first frequency being lower than a frequency of a noise component
Implementation Method 2
acquires a second filtered voltage being the terminal voltage filtered by a second low-pass filter having a second frequency as a cutoff frequency, the second frequency being lower than the first frequency
Data Source
AI summary
At least after off of an injection pulse of partial lift injection, a difference between a first filtered voltage being a negative terminal voltage of a fuel injection valve filtered by a first low-pass filter and a second filtered voltage being the terminal voltage filtered by a second low-pass filter is calculated, and time from a predetermined reference timing to a timing when the difference between the filtered voltages has an inflection point is calculated as voltage inflection time. Subsequently, an injection quantity corresponding to current voltage inflection time is estimated for each of injection pulse widths with a relationship between the voltage inflection time and the injection quantity, the relationship being beforehand stored for each of the injection pulse widths. A map defining the relationship between the injection pulse width and the injection quantity is created based on a result of such estimation, and a required injection pulse width corresponding to a required injection quantity is calculated using the map.