Ignition Timing Control for Hand-Held Combustion Engine Stability
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Solution Overview
Problem
Internal combustion engines in hand-held tools struggle to maintain stable operation under partial load conditions, leading to speed fluctuations and reduced operating comfort due to varying gyroscopic forces and increased noise emissions.
Innovation Solution
A method that adjusts the ignition timing in a hand-held tool's internal combustion engine by setting a later ignition point in the partial load range compared to full-load operation, allowing for stable speed maintenance by suspending ignition in individual engine cycles, and implementing time-dependent ignition adjustments during speed changes to minimize vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an early ignition point is set to maintain power output, then the engine speed increases strongly, but speed fluctuations occur due to strong acceleration and subsequent ignition suspensions
Solution Approach 1:
The patent changes the ignition timing parameter from an early ignition point (used for power optimization) to a later ignition point (used for speed stabilization). This parameter change reduces the strong acceleration effect that causes speed fluctuations, allowing the engine to operate stably in the partial load range while maintaining adequate power output through the controlled acceleration profile.
2Stability of the object's composition
If the ignition point is retarded for stable operation, then speed fluctuations are reduced, but power output decreases due to less energy generated per combustion
Solution Approach 1:
The patent implements a dynamic ignition timing control system that adapts the ignition point based on the current operating conditions. In the partial load range, a later ignition point is used for stability, while the system can transition to earlier ignition timing when higher power is needed or during acceleration phases. This dynamic adjustment allows the engine to optimize between stability and power output depending on the operational requirements.
3Power
If full-load operation is maintained for adequate power, then sufficient energy is generated, but noise emissions increase and operating comfort decreases due to high gyroscopic forces
Solution Approach 1:
The patent changes the operating parameters by implementing a later ignition point in the partial load range, which reduces the peak combustion pressure and energy release rate. This parameter change directly reduces noise emissions and gyroscopic forces, improving operating comfort while maintaining adequate power output for the specific application requirements.
Data Source
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AI summary
The method involves specifying a first ignition timing for each engine speed of a first engine speed range in an internal combustion engine (15). A second ignition timing is specified for each engine speed of a second engine speed range. The first ignition timing is retarded by 5 degree crank angle relative to the second ignition timing. The first engine speed range is selected to extend from a coupling engine speed range to a limit engine speed of approximately 7000 revolutions per minute.