Internal Combustion Engine Fuel Quality Determination via Knock Sensor
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Solution Overview
Problem
Existing methods for controlling internal combustion engines fail to accurately determine fuel quality across all operating ranges, leading to inefficiencies and potential damage due to knocking combustions, as not all cylinders and load/rotational speed ranges are equally suitable for assessing fuel quality.
Innovation Solution
Selecting specific operating ranges and using knock sensor signals to determine fuel quality, with the ignition angle adjustment being a key parameter, and employing a counter to stabilize the evaluation by considering the duration of ignition angle adjustments beyond threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel quality determination is performed across all operating ranges, then comprehensive fuel quality assessment is achieved, but measurement precision deteriorates due to inclusion of unsuitable ranges
Solution Approach 1:
The patent segments the operating range into suitable and unsuitable portions for fuel quality determination. Only operating ranges meeting specific criteria (achieved for specified time duration, appropriate load and rotational speed ranges) are selected for fuel quality learning, while excluding ranges that would compromise measurement precision.
Solution Approach 2:
The patent applies local quality by selecting specific cylinders and specific operating ranges that possess the required qualities for accurate fuel quality determination. Not all cylinders are suitable for learning fuel quality, and not all operating ranges provide reliable data, so the system selectively uses only those portions with appropriate characteristics.
2Measurement precision
If ignition angle adjustment threshold is set low, then fuel quality determination is sensitive to minor variations, but reliability deteriorates due to small fluctuations causing false variations
Solution Approach 1:
The patent implements beforehand cushioning by requiring that the ignition angle adjustment exceeds the threshold value for a specified time duration before triggering fuel quality determination. This time-based cushioning prevents small, transient fluctuations around the threshold from causing false fuel quality variations, while still maintaining sensitivity to genuine fuel quality changes.
3Quantity of substance
If all cylinders are used for fuel quality learning, then data quantity increases, but measurement precision deteriorates due to inclusion of unsuitable cylinders
Solution Approach 1:
The patent segments the cylinder population into suitable and unsuitable groups for fuel quality learning. The control device selectively identifies and uses only those cylinders that meet the required criteria for accurate fuel quality determination, rather than uniformly using all cylinders.
Solution Approach 2:
The patent applies local quality by recognizing that different cylinders have different suitability for fuel quality learning. The system selectively employs only those cylinders with the appropriate characteristics (local quality) for the learning process, ensuring higher measurement precision.
Data Source
AI summary
A method and a device are provided for controlling an internal combustion engine, a knock sensor being provided for acquiring combustion signals of the internal combustion engine. Devices are also provided that, during running operation of the internal combustion engine, select operating ranges of the internal combustion engine that are suitable for a determination of fuel quality, and carry out a determination of the fuel quality in these ranges on the basis of signals of the knock sensor.