Engine Rotation Speed Calculation Using Crankshaft Angular Acceleration
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Solution Overview
Problem
Existing internal combustion engine control systems fail to accurately calculate engine rotation speed in correlation with combustion state and generated torque, leading to inefficient fuel correction and poor startability due to averaging influences of condensation and rarefaction in pulse signal generation.
Innovation Solution
A controller that sets a rotation speed calculation interval across the top dead center of a combustion stroke, using angular speed information of the crankshaft to accurately reflect combustion state and generated torque, allowing for precise torque fluctuation calculation and correction during engine start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If engine rotation speed is calculated by averaging pulse signal generation frequency over one stroke, then calculation simplicity is maintained, but correlation between rotation speed and combustion state deteriorates
Solution Approach 1:
The patent divides the rotation speed calculation into two segments: a first rotation speed from pulse signal averaging and a second rotation speed from angular acceleration detection. These segmented measurements are then combined to achieve both simplicity and accuracy in reflecting combustion state
Solution Approach 2:
The patent introduces angular acceleration as an intermediary parameter to detect combustion state. The angular acceleration sensor acts as a mediator that directly measures combustion-induced crankshaft fluctuations, providing a bridge between mechanical motion and combustion quality
2Reliability
If fuel injection amount is increased to compensate for torque deficiency during start-up, then startability is improved, but rotation speed fluctuation increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring angular acceleration and torque fluctuations during start-up. The ECU adjusts fuel injection amount based on real-time feedback from the angular acceleration sensor, preventing excessive rotation speed fluctuations while ensuring reliable starting
Solution Approach 2:
The patent performs preliminary detection of torque deficiency using angular acceleration measurement before full combustion stabilizes. This preliminary action allows the ECU to pre-adjust fuel injection timing and amount, preventing start-up failures without causing rotation speed instability
3Measurement precision
If rotation speed calculation interval is set across top dead center of combustion stroke, then correlation with generated torque is improved, but calculation timing complexity increases
Solution Approach 1:
The patent uses periodic crank angle signals to trigger rotation speed calculations at specific phases of the combustion cycle. By synchronizing calculations with periodic crankshaft position signals, the system achieves precise timing without complex continuous monitoring
Data Source
AI summary
A rotation speed calculation interval is set near a combustion top dead center of each cylinder of an engine. An interval rotation time necessary for a crankshaft to rotate through the rotation speed calculation interval is calculated as angular speed information of the crankshaft in the rotation speed calculation interval for each combustion stroke of the engine. Engine rotation speed is calculated based on the interval rotation time. The angular speed information of the crankshaft in the rotation speed calculation interval set near the combustion top dead center reflects a combustion state or generated torque. By calculating the engine rotation speed based on the angular speed information, the engine rotation speed highly correlated with the combustion state or the generated torque of the engine can be calculated.