Two-Stroke Ignition Device Voltage Control
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Solution Overview
Problem
In two-stroke engines, the existing ignition devices can cause uncontrolled combustion and irregular engine running due to ignition of the mixture at the bottom dead center of the piston, leading to unwanted ignition sparks at atmospheric pressure.
Innovation Solution
An ignition device with a magnet wheel, yoke assembly, and switch element that reduces the voltage applied to the spark plug during the bottom dead center rotational angle region, preventing unwanted ignition by short-circuiting the primary coil or using a pre-sparking gap or blocking diode to suppress high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnet wheel and ignition device are configured to induce high voltage in the secondary coil during bottom dead center rotation, then a strong ignition spark is achieved, but unwanted ignition of the mixture occurs at atmospheric pressure in the combustion chamber
Solution Approach 1:
The rotational angle range of the magnet wheel is segmented into different regions: a first rotational angle region around top dead center where high voltage is permitted for reliable ignition, and a second rotational angle region around bottom dead center where high voltage is suppressed to prevent unwanted ignition. This spatial segmentation allows different voltage control strategies in different angular zones.
Solution Approach 2:
The ignition control unit preliminarily determines whether to permit high voltage based on the detected rotational angle of the magnet wheel before the ignition event occurs. By pre-assessing the rotational angle region, the control unit can proactively enable or suppress high voltage output, preventing unwanted ignition before it occurs while ensuring reliable ignition when needed.
2Stability of the object's composition
If high voltage is suppressed during bottom dead center to prevent unwanted ignition, then engine stability is improved, but the ability to trigger ignition spark at atmospheric pressure is reduced
Solution Approach 1:
The ignition control device applies different voltage control characteristics to different rotational angle regions. In the first region around top dead center, high voltage is permitted to ensure reliable ignition capability. In the second region around bottom dead center, high voltage is suppressed to maintain engine stability. This local differentiation of control quality resolves the contradiction by applying appropriate voltage levels only where needed.
Solution Approach 2:
The ignition control unit dynamically changes the voltage output parameter based on the detected rotational angle of the magnet wheel. When the angle indicates top dead center proximity, the control unit permits high voltage output for reliable ignition. When the angle indicates bottom dead center proximity, the control unit suppresses high voltage to prevent unwanted ignition. This dynamic parameter adjustment resolves the contradiction between ignition capability and engine stability.
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
Ensures reliable ignition only at the top dead center, preventing uncontrolled combustion and maintaining engine stability by reducing high voltages induced at the bottom dead center, thus preventing ignition sparks at atmospheric pressure.
Implementation Method 1
a voltage is induced in the coils by the two permanent magnets in the region of the bottom dead center
Implementation Method 2
The charging coil for charging the ignition capacitor is wound around one arm of the U-shaped yoke
Implementation Method 3
the ignition coil made up of a primary coil and a secondary coil is wound around the other arm
Data Source
AI summary
The invention relates to an ignition device for triggering an ignition spark at a spark plug by way of an ignition generator. The latter includes a magnet wheel, which has two permanent magnets arranged at a spacing from each other in the peripheral direction and a magnetic yoke. The magnetic yoke carries a charging coil which charges an ignition capacitor, a primary coil and a secondary coil connected to the spark plug. During every passing of a permanent magnet, a voltage is induced in the coils, wherein, in order to trigger the ignition spark, the ignition capacitor is discharged via a switch element. In order to avoid an unwanted ignition at the bottom dead center of the piston, a device for reducing the voltage that occurs at the spark plug is provided.