Crankshaft Speed Variation Ignition Timing Control
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Solution Overview
Problem
Existing engine ignition timing setting systems struggle to precisely verify the knocking occurrence limit and set appropriate ignition timing, especially due to the expense and limitations of knock sensor systems, which can lead to inefficient engine operation and increased emissions.
Innovation Solution
An ignition timing setting apparatus that includes a pulse generator, crank angular speed variation calculator, engine load estimator, and ignition timing determiner, utilizing engine temperature and speed data to set optimal ignition timing and avoid knocking ranges by estimating indicated mean effective pressure from crank angular speed variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a knock sensor is installed to detect knocking and control ignition timing, then knocking can be avoided and engine efficiency improved, but the system becomes expensive and complex
Solution Approach 1:
The patent extracts the knock detection function from the expensive knock sensor system and implements it through a simpler crankshaft rotational speed variation detection system. By measuring the variation in crankshaft rotational speed caused by knocking, the system eliminates the need for complex sensor arrays while maintaining knocking detection capability.
Solution Approach 2:
The patent replaces the electronic sensing system (knock sensors) with a mechanical measurement approach (crankshaft rotational speed variation). This substitution uses the natural mechanical response of the crankshaft to knocking events, eliminating the need for expensive piezoelectric or capacitive sensors.
2Use of energy by moving object
If ignition timing is advanced to improve thermal efficiency, then fuel economy improves, but knocking occurs
Solution Approach 1:
The patent implements a feedback control system that continuously monitors crankshaft rotational speed variation and uses this information to adjust ignition timing in real-time. When knocking is detected through speed variation, the system feedback-adjusts the ignition timing to prevent further knocking while maintaining optimal fuel economy.
Solution Approach 2:
The patent makes the ignition timing control dynamic by continuously adjusting it based on real-time engine conditions. Rather than using fixed timing maps, the system dynamically adapts ignition timing to the current operating state, allowing maximum timing advance when conditions permit and retarding timing when knocking is detected.
3Ease of operation
If engine load is detected through intake air volume measurement, then ignition timing can be controlled, but the system depends on expensive vacuum sensors and throttle sensors
Solution Approach 1:
The patent makes the engine load detection self-service by using the engine's own operational characteristics (crankshaft rotational speed variation) rather than external sensors. The system uses the natural variation in crankshaft speed that occurs during different load conditions, eliminating the need for separate vacuum sensors or throttle position sensors.
Data Source
AI summary
An ignition timing setting apparatus includes a pulse generator for generating crank pulses corresponding to crank angles, a crank angular speed variation calculating section for calculating a crank angular speed variation based on an interval of the crank pulses, an engine load estimating section for estimating an indicated mean effective pressure from the crank angular speed variation, and an ignition timing determining section having an ignition timing control map for determining an ignition timing advance quantity in accordance with the estimated indicated mean effective pressure and an engine temperature or an engine speed. Such ignition timing setting apparatus sets appropriate ignition timings for avoiding a knocking occurrence load range based on an accurate estimated engine load.