Crankshaft Angular Acceleration Calculator for Engine Combustion Estimation
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Solution Overview
Problem
Existing methods for measuring combustion state in internal combustion engines are limited by the need for durable and cost-effective cylinder pressure sensors, and they fail to accurately calculate crank angular acceleration and estimate gas pressure torque, especially when external torque is not zero or when additional sensors are required.
Innovation Solution
An angular velocity/angular acceleration calculator using a crank angle sensor signal, which includes a crank angle detection device, correction device, and calculation device to accurately calculate crank angular velocity and acceleration, and a torque estimator that applies these values to an equation of motion to estimate gas pressure and external torque, enabling precise combustion state estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cylinder internal pressure sensor is used to measure combustion state, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses crank angle sensor signals as an intermediary to indirectly measure combustion state. Instead of directly measuring cylinder pressure with a pressure sensor, the system uses the crank angle sensor to detect crankshaft position and calculates angular acceleration, which serves as a mediator to estimate gas pressure torque and combustion state, thereby avoiding the need for complex and expensive pressure sensors
Solution Approach 2:
The patent replaces the mechanical pressure sensor system with a computational approach using crank angle data. By substituting the direct mechanical measurement system with a signal processing system that calculates angular acceleration from crank angle signals, the invention eliminates the need for durable but expensive pressure sensors while maintaining measurement capability
2Device complexity
If average angular acceleration is calculated over a predetermined crank angle range, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent transitions from static average calculation to dynamic instantaneous calculation. By using a sliding window approach that continuously updates the angular acceleration calculation based on recent crank angle data, the system captures the dynamic variations in angular acceleration throughout the crank angle range, providing precise instantaneous values rather than blurred averages
Solution Approach 2:
The patent performs preliminary correction of crank angle signals before calculating angular acceleration. By pre-processing the crank angle data to remove systematic errors and normalize the signal, the subsequent angular acceleration calculation achieves higher precision without requiring complex calculation systems
3Device complexity
If only friction torque is stored as a map, then device complexity is reduced, but measurement precision deteriorates due to inability to estimate gas pressure torque when external torque is not zero
Solution Approach 1:
The patent implements a feedback mechanism where the calculated angular acceleration is used to estimate gas pressure torque, which then feeds back into the overall torque estimation. By continuously using the measured angular acceleration to update the torque estimation and accounting for external torque effects, the system achieves accurate gas pressure torque estimation even when external torque is not zero, without requiring additional complex measurement devices
Solution Approach 2:
The system uses its own calculated angular acceleration data to estimate both friction torque and gas pressure torque. By making the system self-sufficient and using its measured data to compensate for the absence of external torque measurements, the invention achieves comprehensive torque estimation without additional sensors or complex external torque maps
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 solution allows for highly accurate calculation of crank angular velocity and acceleration, and estimation of gas pressure and external torque, leading to improved combustion state estimation and engine control without the need for expensive sensors, enhancing durability and cost-effectiveness.
Implementation Method 1
converting a function of the time with respect to the crank angle corrected by the crank angle correction device so as to be regarded as a periodic function, and utilizing the discrete Fourier transform of the converted function
Data Source
AI summary
An angular velocity/angular acceleration calculator of the crankshaft in an internal combustion engine includes a crank angle detection device, a crank angle correction device, and an angular velocity/angular acceleration calculation device. The crank angle detection device detects a crank angle in the internal combustion engine and a time at the crank angle. The crank angle correction device corrects the crank angle and the time thus detected to an equiangular crank angle and a time corresponding thereto. The angular velocity/angular acceleration calculation device calculates an angular velocity and an angular acceleration of the crankshaft by converting a function of the time with respect to the crank angle that are corrected by the crank angle correction device so as to be regarded as a periodic function, and utilizing the discrete Fourier transform of the converted function.