Air/Fuel Ratio Control for General-Purpose Engines
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Solution Overview
Problem
Conventional air/fuel ratio control systems for engines using mixed fuel fail to select appropriate fuel injection characteristics before engine start, especially in varying environments such as high alcohol rates, temperatures, and altitudes, leading to improper engine starting.
Innovation Solution
An air/fuel ratio control apparatus with a desired engine speed input switch, engine speed detector, throttle opening regulator, fuel injection amount calculator, and injector, along with operator-manipulable switches for selecting fuel injection amount characteristics, allowing for proper engine starting in various environments by calculating and adjusting fuel injection based on detected speed and throttle opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air/fuel ratio control systems wait for engine start to detect air/fuel ratio deviation and estimate alcohol rate, then the system structure remains simple, but the engine cannot be properly started in high alcohol rate environments or varying temperature and altitude conditions
Solution Approach 1:
The system performs preliminary selection of fuel injection characteristics before engine start by providing multiple pre-configured characteristic sets corresponding to different alcohol rates, temperatures, and altitudes. The operator can pre-select the appropriate characteristics based on the operating environment, enabling proper engine starting without waiting for post-start detection and estimation.
2Adaptability or versatility
If multiple sets of fuel injection amount characteristics are provided for different alcohol rates, then the system can adapt to various fuel compositions, but the device complexity increases requiring operator intervention to select appropriate characteristics
Solution Approach 1:
The system provides dynamic adaptability by allowing operator selection among multiple pre-configured fuel injection characteristics sets. Each set is optimized for specific alcohol rates, temperatures, and altitudes, enabling the system to adapt to different operating conditions while maintaining ease of operation through a user-friendly selection interface.
3Reliability
If the system uses pre-configured fuel injection characteristics for different environments, then proper engine starting is achieved in various conditions, but the system requires manual switching between characteristic sets
Solution Approach 1:
The system prepares multiple fuel injection characteristics sets in advance, each optimized for specific environmental conditions (alcohol rates, temperatures, altitudes). The operator can pre-select the appropriate characteristics before engine start, ensuring reliable starting in various environments without requiring complex real-time adjustments or manual switching during operation.
Data Source
AI summary
In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount determined for mixed fuel based on fuel injection amount characteristics is increased/decreased when a load is kept constant and the output air/fuel ratio is estimated to correct the fuel injection amount by the estimated air/fuel ratio, while a switch (knob) is installed to be manipulated by the operator to switch the fuel injection amount characteristics.