Ignition Timing Control for Engine Deceleration
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Solution Overview
Problem
Internal combustion engines in motor-driven tools experience undesirable prolonged high-speed operation when decelerating with biofuels, leading to poor running behavior, as they tend to remain at high speeds during lean mode deceleration, affecting user experience and operational efficiency.
Innovation Solution
An ignition control system that adjusts ignition timing to a 'late' setting when engine speed drops above idling but below initial clutch engagement speed, ensuring rapid speed reduction by increasing combustion frequency but reducing combustion strength, thereby improving running behavior regardless of fuel type used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the internal combustion engine uses biofuel with high alcohol content, then the engine can operate with alternative fuel, but the engine remains at high speed for an undesired long time during deceleration in lean mode
Solution Approach 1:
The ignition control device dynamically adjusts ignition timing based on real-time engine operating conditions (speed, load, throttle position). During deceleration in the critical speed range, the system dynamically retards ignition timing to accelerate speed reduction, while maintaining adaptive ignition timing for different fuel types (conventional or biofuel) to ensure optimal combustion characteristics for each fuel variety.
Solution Approach 2:
The invention changes the ignition timing parameter dynamically during deceleration events. When the engine speed enters the critical range (above idling but below clutch engagement speed) during deceleration, the ignition timing is retarded relative to the idle timing. This parameter change accelerates the speed reduction process and eliminates the prolonged high-speed state, while the system maintains different ignition timing characteristics for different fuel types.
2Speed
If the ignition timing is adjusted to 'late' during deceleration, then the engine speed reduces quickly to idling levels, but the combustion strength is reduced
Solution Approach 1:
The system applies preliminary anti-action by retarding ignition timing before the engine speed drops too low during deceleration. This proactive timing adjustment prevents the engine from remaining at high speed for an extended period, while the timing retardation is applied in a controlled manner to manage the reduction in combustion strength and avoid excessive rough running or stalling conditions.
Solution Approach 2:
The ignition timing retardation is applied partially - only during the specific critical deceleration phase when engine speed is above idle but below clutch engagement speed. The system does not continuously retard timing in all operating conditions, but applies the timing adjustment selectively to the specific deceleration scenario where it is most needed, balancing speed reduction with combustion quality.
3Ease of operation
If the throttle flap is suddenly closed during full load operation, then the engine decelerates, but with biofuel the engine remains at high speed level for an undesired long time
Solution Approach 1:
The ignition control device continuously monitors engine operating parameters (speed, load, throttle position) and uses this feedback to determine when deceleration events occur. When the system detects that the engine is decelerating and enters the critical speed range, it automatically adjusts ignition timing to retard relative to idle timing, creating a feedback-controlled response that accelerates speed reduction after throttle closure regardless of fuel type.
Solution Approach 2:
The system prepares for deceleration by having pre-programmed ignition timing characteristics for different operating conditions. When throttle closure is detected, the control device immediately switches to the appropriate deceleration ignition timing map that includes the retarded timing for the critical speed range, providing a preliminary prepared response that quickly addresses the high-speed persistence issue without requiring complex real-time calculations.
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
The solution effectively reduces engine speed quickly to idling levels during deceleration, maintaining good running behavior by adjusting ignition timing through specific characteristic curves, minimizing negative effects on rich or lean deceleration, and ensuring smooth acceleration and idling.
Implementation Method 1
an ignition device and an ignition control device for controlling the ignition timing
Implementation Method 2
an internal combustion engine which drives at least one tool via a clutch
Data Source
AI summary
A working apparatus has an internal combustion engine which drives at least one tool via a clutch. The clutch starts the coupling process at an initial engagement speed when the internal combustion engine is accelerated. The internal combustion engine has a piston, an ignition device and an ignition timing control device. The control device provides a first ignition timing for idling and a second ignition timing for full load operation, which is earlier than the first ignition timing. A method for operating the working apparatus provides that the ignition timing is adjusted toward “late,” with respect to the first ignition timing, when the engine speed drops in a first speed range above the idling speed and below the initial engagement speed.