General-Purpose Engine Ignition Control Apparatus
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Solution Overview
Problem
General-purpose internal combustion engines face reduced ignition plug lifespan due to unnecessary 'waste ignition' signals generated during both compression and exhaust strokes, leading to increased complexity and size in existing solutions.
Innovation Solution
An apparatus and method that utilize an engine speed detector, average engine speed calculator, ignition cutter, after-ignition-cut engine speed detector, and ignition signal discriminator to selectively cut and control ignitions based on whether they occur in the compression or exhaust stroke, using an electronic control unit to determine the stroke type and prevent waste ignitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ignition signals are produced in both compression stroke and exhaust stroke to simplify engine structure, then the structure is simplified, but the ignition plug duration life is shortened due to waste ignition
Solution Approach 1:
The patent extracts and eliminates the harmful waste ignition function while preserving the useful normal ignition function. By introducing an ignition cutter that selectively interrupts ignition signals based on stroke detection, the system removes the detrimental exhaust stroke ignition without requiring complete structural redesign, thus extending ignition plug life while maintaining structural simplicity
Solution Approach 2:
The patent implements a feedback mechanism where the ignition controller continuously monitors engine operation state through stroke detection and dynamically adjusts ignition signal output. The ignition cutter receives feedback about current stroke type and automatically cuts exhaust stroke ignition signals, creating a closed-loop control system that protects the ignition plug without complex mechanical modifications
2Duration of action of stationary object
If a reluctor and pulser are provided on a camshaft to produce only normal ignition signals, then ignition plug life is extended, but the camshaft portion grows in size and complexity
Solution Approach 1:
The patent makes the existing ignition signal generation system multi-functional by enabling it to serve both normal ignition and waste ignition purposes simultaneously. Instead of adding dedicated components for stroke differentiation, the system uses the same ignition signals for both functions, with electronic control determining which function is active, thereby avoiding camshaft structural complexity
Solution Approach 2:
The patent replaces mechanical stroke differentiation mechanisms (such as reluctors and pulsers on the camshaft) with an electronic control system. The ignition controller uses electronic signal processing and timing analysis to distinguish between compression and exhaust strokes, substituting mechanical complexity with electronic intelligence and avoiding physical modifications to the camshaft
3Measurement precision
If two pairs of projections and electromagnetic coils are used for pulse generation to determine compression or exhaust stroke, then accurate ignition control is achieved, but the structure becomes inadequate for compact general-purpose engines
Solution Approach 1:
The patent enables the existing ignition system to self-differentiate between compression and exhaust strokes by analyzing the characteristics and timing of ignition signals it already generates. The ignition controller uses the engine's own operational parameters (ignition timing, signal intervals) to determine stroke type, eliminating the need for separate detection components and maintaining compact engine dimensions
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 extends the lifespan of ignition plugs by accurately discriminating between necessary and unnecessary ignitions, maintaining a simple and compact engine structure while ensuring efficient combustion.
Implementation Method 1
an electromagnetic coil and a magnet are attached to the camshaft at a position opposite to each other, and a pulse signal generation portion having a protrusion is provided on the camshaft
Data Source
AI summary
In an apparatus for controlling ignition of a general-purpose internal combustion engine in which an ignition signal is produced both in a compression stroke and in an exhaust stroke of a four stroke cycle, one of the ignitions to be conducted based on the produced two ignition signals is cut and an after-ignition-cut engine speed is detected. Then it is discriminated whether each of the two ignition signals was produced in the compression stroke or in the exhaust stroke based on a difference between an average engine speed and the after-ignition-cut engine speed, and the ignition is controlled based on the ignition signal discriminated to be produced in the compression stroke in the two ignition signals, thereby enabling to improve the duration life of an ignition plug, with simple and compact structure.