Alternating Ignition Timing for Two-Stroke Engine Speed Control
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Solution Overview
Problem
Two-stroke combustion engines face premature wear and inefficiency due to unregulated high engine speeds during low load conditions, leading to increased pollutants and noise, and existing methods like ignition timing adjustment and cut-out result in power loss and uneven output.
Innovation Solution
A control unit that alternates ignition timing in a step-wise mode in response to engine speed, adjusting between specific spans relative to the top dead center position to control engine speed, and optionally skipping ignition for certain revolutions, to prevent excessive speed increases and maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ignition timing is retarded to very close to TDC to regulate engine speed, then engine speed is controlled, but unburned fuel blows out in the exhaust muffler causing power loss, increased pollutants and noise
Solution Approach 1:
The patent applies periodic action by alternating between two different ignition timing positions (first and second positions) in a periodic manner. This prevents the engine from continuously operating at a single retarded ignition timing that causes fuel blowout, thereby reducing pollutants while still controlling engine speed through the alternating timing adjustments.
2Speed
If ignition timing is retarded to very close to TDC to regulate engine speed, then engine speed is controlled, but power output is reduced
Solution Approach 1:
By periodically alternating between an advanced first ignition timing position and a retarded second ignition timing position, the system maintains higher average power output compared to continuous retardation. The periodic switching ensures that during the advanced timing phase, power output is maximized while still achieving speed control through the overall retarded average timing.
3Speed
If cut-out is employed to regulate engine speed, then engine speed is controlled and exhaust gas temperature decreases, but unburned gases blow out increasing pollutants
Solution Approach 1:
The patent replaces the cut-out method with periodic alternation of ignition timing positions. Instead of completely skipping ignition (cut-out) which causes unburned fuel blowout, the system periodically applies ignition at two different timing positions. This ensures continuous combustion and prevents unburned gas emissions while still achieving engine speed control through the periodic timing adjustments.
4Speed
If cut-out is employed to regulate engine speed, then engine speed is controlled, but power output becomes uneven
Solution Approach 1:
The periodic alternation between two ignition timing positions provides a more uniform power output compared to cut-out. Since ignition occurs every cycle (unlike cut-out where ignition is skipped), the power delivery remains consistent and smooth. The periodic timing variation is subtle enough to maintain power uniformity while effectively controlling engine speed.
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
This approach effectively regulates engine speed, preventing damage, reducing pollutants, and ensuring consistent power output by dynamically adjusting ignition timing based on engine conditions, thereby enhancing engine performance and efficiency.
Implementation Method 1
a spark ignites the air-fuel mixture in a cylinder during compression stroke
Data Source
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AI summary
The invention relates to methods and means of regulating the speed of a two-stroke combustion engine. An arrangement for alternating an ignition timing relative to a top dead center position is provided. For a given engine speed, the ignition timing may be step-wise adjustable. One or more steps may be used while alternating between two ignition timings. The ignition timing may be adjusted when the engine speed increases above a threshold engine speed.