Fuel Shortage Detection for General-Purpose Engine
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Solution Overview
Problem
General-purpose internal combustion engines with electronic governors experience unstable engine speed and afterburning due to fuel shortages, as the insufficient fuel supply leads to unstable air-fuel ratios and increased throttle opening, causing issues like afterburning and backfire.
Innovation Solution
A fuel shortage detecting apparatus that includes a fuel shortage condition detector and an engine stopper, which detects when the engine is in a fuel shortage condition and stops the engine to prevent such issues, using sensors and an Electronic Control Unit (ECU) to monitor engine speed, throttle opening, and fuel pump current to determine if the engine is in a low-speed, wide-open throttle condition for an extended period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is immediately stopped when the switch is turned off, then the engine stop response is fast, but fuel shortage conditions cause unstable engine speed and afterburning
Solution Approach 1:
The system performs preliminary detection of fuel shortage conditions before the engine is stopped. The detection unit continuously monitors engine parameters (speed, throttle opening, fuel pump current) to identify fuel shortage conditions in advance, allowing the control unit to prepare appropriate stop procedures before actual shutdown occurs.
Solution Approach 2:
The system implements feedback control by continuously monitoring engine operating parameters and comparing them against predetermined thresholds. The detection unit receives real-time data from sensors measuring engine speed, throttle valve opening, and fuel pump current, adjusting the stop procedure based on this feedback to prevent unstable operation and afterburning.
2Speed
If the throttle opening is increased to maintain engine speed during fuel shortage, then the engine speed is maintained, but the air-fuel ratio regulation becomes unstable and causes afterburning
Solution Approach 1:
The system uses feedback control to monitor the air-fuel ratio and throttle opening in real-time. When fuel shortage is detected, the control unit adjusts the throttle valve opening based on feedback from sensors, preventing excessive increases that would cause unstable air-fuel ratios and afterburning while maintaining adequate engine speed.
Solution Approach 2:
The system changes operating parameters dynamically by adjusting the throttle valve opening and fuel injection timing based on detected fuel shortage conditions. The control unit modifies these parameters to maintain optimal air-fuel ratio within a predetermined range, preventing the extreme lean conditions that lead to afterburning and backfire.
3Duration of action of stationary object
If the engine operates under fuel shortage conditions, then the engine can continue running, but unstable air-fuel ratio leads to afterburning and backfire
Solution Approach 1:
The system performs preliminary detection and identification of fuel shortage conditions before they cause harmful effects. By continuously monitoring engine parameters and comparing them against predetermined thresholds, the system identifies fuel shortage conditions early and initiates appropriate stop procedures to prevent afterburning and backfire.
Solution Approach 2:
The system implements continuous feedback monitoring of engine operating parameters including speed, throttle opening, and fuel pump current. This feedback mechanism allows the control unit to detect fuel shortage conditions and adjust operation accordingly, preventing the development of unstable air-fuel ratios that would cause afterburning and backfire.
Data Source
AI summary
In an apparatus for detecting fuel shortage of a general-purpose internal combustion engine connectable to an operating machine to be used as a prime mover of the machine, the engine being supplied with fuel stored in a tank and having an actuator adapted to open and close a throttle valve installed in an air intake pipe so as to achieve a desired engine speed set by an operator, comprising a fuel shortage condition detector adapted to detect whether the engine is in a fuel shortage condition, and an engine stopper adapted to stop the engine when the engine is detected to be in the fuel shortage condition. With this, it becomes possible to detect whether the engine having the electronic governor is in the fuel shortage condition, thereby preventing occurrence of trouble such as afterburning.