Variable-Fuel Engine Control Using Alcohol Concentration Maps
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Solution Overview
Problem
Conventional fuel injection control systems for variable-fuel engines have a narrow adjustment range for fuel injection quantity in response to changes in alcohol concentration, leading to instability and limited operation flexibility.
Innovation Solution
A fuel injection control apparatus with multiple maps that correlate engine state and basic fuel injection time to alcohol concentration, using sensors to detect alcohol concentration and select the appropriate map for determining fuel injection quantity, eliminating the need for an alcohol concentration sensor and enhancing stability and response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single basic fuel injection time map is used for all alcohol concentrations, then the device complexity is reduced, but the adaptability to different alcohol concentrations deteriorates
Solution Approach 1:
The single basic fuel injection time map is segmented into multiple maps corresponding to different alcohol concentration ranges (e.g., first map for 0-30%, second map for 30-70%, third map for 70-100%). The ECU selects the appropriate map based on the detected alcohol concentration, enabling precise fuel injection control for each concentration level while maintaining a manageable system structure through clear segmentation.
Solution Approach 2:
The system dynamically switches between different basic fuel injection time maps based on the detected alcohol concentration. Instead of using a static single map, the ECU selects the most appropriate map in real-time according to the fuel type being used, allowing the fuel injection control to adapt dynamically to varying alcohol concentrations and maintain optimal performance across the full range of possible fuel compositions.
2Ease of operation
If the basic fuel injection time is preliminarily set for each engine rotary speed and intake pressure, then the ease of operation is improved, but the adaptability to alcohol concentration changes deteriorates
Solution Approach 1:
Different basic fuel injection time maps are created with locally optimized values for specific alcohol concentration ranges. Each map contains preliminarily set fuel injection times that are specifically tuned for its target alcohol concentration range, providing locally optimal control characteristics. This allows the system to maintain ease of operation through pre-set values while achieving adaptability by selecting the map that best matches the current alcohol concentration.
3Measurement precision
If an alcohol concentration sensor is installed to directly detect alcohol concentration, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
Instead of directly measuring alcohol concentration, the system uses the air-fuel ratio correction coefficient as an intermediary parameter. The O2 sensor measures oxygen concentration in exhaust gas, and the ECU calculates the air-fuel ratio correction coefficient based on this measurement. This coefficient then serves as a proxy for alcohol concentration, allowing the system to indirectly determine fuel composition without requiring a direct alcohol concentration sensor, thus reducing system complexity and cost while maintaining sufficient measurement precision for map selection.
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
Broadens the adjustment range of fuel injection quantity with respect to alcohol concentration, stabilizing engine operation and reducing costs by estimating alcohol concentration based on air-fuel ratio correction coefficients, while ensuring stable idling and enhanced high-load response.
Implementation Method 1
an air-fuel ratio correction coefficient which is obtained using a detection value of an oxygen sensor (hereinafter referred to as "O2 sensor") which measures the concentration of oxygen contained in an exhaust gas
Data Source
AI summary
A fuel injection control apparatus, for a variable-fuel engine, includes a plurality of stored maps for determining a basic fuel injection time corresponding to a state of an engine and alcohol concentration in the fuel. The apparatus includes a memory storage region which stores the fuel injection control maps. The apparatus also includes an oxygen sensor disposed in an exhaust pipe for detecting oxygen concentration in an exhaust gas; a basic fuel injection time calculator which determines the basic fuel injection time using the currently selected fuel injection control map; a correction coefficient calculator which determines an air-fuel ratio correction coefficient for correcting the basic fuel injection time; a fuel injection quantity calculator; and a map changeover part which selects the fuel injection control map of the concentration of alcohol close to the concentration of alcohol of the fuel based on the air-fuel ratio correction coefficient.