Fuel Injection Control Device Disturbance Suppression
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Solution Overview
Problem
Existing fuel injection control systems face challenges in accurately calculating the maximum injection rate due to variations in pressure waveforms caused by disturbances such as pressure pulsation from preceding injections and valve-opening pulsation, leading to inaccuracies in determining the corresponding pressure decrease amount.
Innovation Solution
A fuel injection control device that calculates a reference interval and sets an integration interval to suppress the influence of disturbances, allowing for the accurate calculation of the corresponding pressure decrease amount by integrating the fuel pressure decrease within this interval, which is set to be equal to or longer than a specified cycle to account for local maximum and minimum points, thereby canceling their influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure decrease amount is calculated based on instantaneous pressure waveform, then the calculation is simple and fast, but the accuracy is low due to disturbances from preceding injections and valve-opening pulsation
Solution Approach 1:
The pressure waveform is segmented by identifying specific intervals: the decrease interval where pressure decreases as injection rate increases, and the increase interval where pressure increases as injection rate decreases. The reference interval is calculated between the end time of the decrease interval and the start time of the increase interval, dividing the complex waveform into manageable segments for accurate measurement.
Solution Approach 2:
The integration interval is extracted from the reference interval by setting it to start from the end time of the decrease interval and extend for a specified cycle duration. This extracted interval specifically captures the pressure decrease portion while excluding disturbance periods, isolating the relevant data for accurate calculation.
2Reliability
If the integration interval is set to include local maximum and minimum points, then disturbances are canceled out, but the interval length increases requiring more data processing
Solution Approach 1:
The integration interval is set to span a specified cycle that includes complete periodic variations of pressure waveforms. By integrating over this periodic interval that encompasses local maximum and minimum points, the positive and negative disturbances cancel each other out, achieving reliable average values that are robust against periodic disturbances.
3Measurement precision
If the reference interval is calculated from end of decrease interval to start of increase interval, then the integration interval can exclude disturbance periods, but the timing precision requirements increase
Solution Approach 1:
The calculation process uses feedback by continuously monitoring the pressure waveform to detect the end time of the decrease interval and the start time of the increase interval. These detected time points feed back into defining the reference interval and subsequent integration interval, creating a closed-loop system that adapts to actual waveform characteristics and maintains precision.
Data Source
AI summary
A fuel injection control device includes a reference interval calculation section that calculates a reference interval between an end time of a decrease interval where the pressure decreases as a fuel injection rate increases and a start time of an increase interval where the pressure increases as the fuel injection rate decreases on a pressure waveform detected by the pressure sensor, an integration interval setting section that sets, in the reference interval, an integration interval where an influence of a disturbance on the fuel pressure decrease due to a target injection is suppressible, and a decrease amount calculation section that calculates a corresponding pressure decrease amount, which is a fuel pressure decrease amount corresponding to a maximum injection rate of fuel of the target injection, based on an integral value obtained by integrating the fuel pressure decrease amount due to the target injection in the integration interval.