Engine Ignition Resumption Control to Suppress Run-On Combustion
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Solution Overview
Problem
Existing engine control systems fail to effectively prevent the run-on phenomenon, where residual fuel continues to burn after engine stop, leading to gum-like substances and valve clogging, and prolonged engine activation upon restart.
Innovation Solution
Implement a control device that resumes ignition control after a predetermined time or when engine rotation falls below a threshold, using ignition timings that deviate from the normal working range to suppress run-on combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel supply is cut off immediately after engine stop, then the run-on phenomenon is prevented, but gummy substances form causing valve sticking and fuel injection nozzle clogging
Solution Approach 1:
The control device performs preliminary action by continuing fuel supply for a predetermined period after engine stop before cutting it off. This preliminary fuel supply prevents residual gas cooling and gum formation, eliminating the harmful effect of valve sticking and nozzle clogging while still preventing run-on combustion through controlled ignition resumption
2Object-generated harmful factors
If ignition control is continued after engine stop, then residual fuel is swept away from intake system, but engine may be activated by ignition plug firing
Solution Approach 1:
The control device applies local quality by using different ignition timing strategies for different purposes. Normal ignition timing is used to sweep residual fuel, while a restricted ignition timing range is applied when resuming ignition after engine stop to prevent engine activation. This localized differentiation of ignition timing quality resolves the contradiction between eliminating residual fuel and preventing unintended activation
3Object-generated harmful factors
If ignition timing is set in normal working area after engine stop, then residual fuel ignition sweeps intake system, but engine continues to work extending stop duration
Solution Approach 1:
The control device changes the ignition timing parameter from the normal working area range to a restricted range after engine stop. By setting ignition timing outside the normal working area (e.g., using retarded timing or timing that does not correspond to any compression stroke), the system prevents engine activation while still allowing residual fuel combustion to occur, thereby reducing run-on duration without extending overall stop time
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
Reduces the duration of run-on phenomenon and prevents engine activation by residual fuel ignition, ensuring quicker engine stop and improved responsiveness.
Implementation Method 1
residual fuel is sucked into the combustion chamber and then ignited by the ignition plug
Implementation Method 2
power supply to an ignition plug is suspended to stop the engine
Data Source
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AI summary
An ignition resumption control unit (40) is disposed that resumes control of an ignition plug (14) if a first predetermined time has elapsed or if engine rotation number has fallen below a threshold value, after receiving an engine stop signal. The ignition resumption control unit (40) executes the control of the ignition plug (14), based on resumption ignition timings (Tg(R-on)) that are timing deviating from an entire ignition timing range set in a normal working area of an engine body (2).