An indirect method for assessing the identity of power unit operating cycles is proposed. The frequency-modulated signal of the speed of rotation of the crankshaft is chosen as a source of input information. With the use of nozzles that have piezoelectric control means, the conceptual principles of software movements of hardware devices to ensure the identity of work cycles have been developed. Direct digital control and feedback control methods are used to design the hardware architecture. The torque of an individual cylinder was approximated on the basis of the Fourier transform taking into account the sequence of their work. A mechanical system with four degrees of freedom is proposed as a deterministic mathematical model of the torque circuit of the power unit. The movements of the masses of the model are described by a system of differential equations, provided that friction is taken into account. The parameters of the system are normalized and the Laplace transform under zero initial conditions is used for its solution. The information links between the torques and the measurement information signal were established using the method of determinants and the theory of signal graphs. It was found that these methods give almost identical calculation results. Algorithmic support for assessing the identity of work cycles is built on the solution of a redefined system of algebraic equations with optimization of the result based on the method of least squares. The Monte Carlo method was used as a mathematical tool for the computer simulation of random disturbances. Computer modeling of the effects of interference on the measurement information signal and on the phase delays of individual cylinders established the requirements for the metrological characteristics of the hardware
The idea of monitoring the identity of the cylinder capacities of an internal combustion engine under conditions of incomplete information is proposed and a computer system is built on its basis. The signal of the instantaneous rotation speed of the crankshaft of the power unit was used as input information. In the development of the hardware architecture, injectors with piezoelectric actuators, the principle of direct digital control, and the principle of control with feedback on the state of fluctuations of the crankshaft rotation speed were used. The Laplace transform was used as a mathematical apparatus for analyzing the structural diagram of a computer system for programmed control of the processes of supplying fuel and air to the cylinders of the power unit. Mathematical models of the components of the hardware for controlling the processes of supplying the fuel-air mixture were constructed, and as a result of the analysis of the structural diagram of the computer system, the transfer function was obtained. Using the capabilities of the Matlab software environment, the transient and impulse transient characteristics of the system are obtained, the Nyquist hodograph is constructed, and the logarithmic amplitude-frequency characteristics of the hardware are established. It was found that the frequency characteristics of the mathematical model of a computer system have the necessary dynamic characteristics. Using the method of expansion into simple fractions, an expression is obtained for a discrete transfer function, the coefficients of the power polynomials of which are established using the method of determinants and computational capabilities of the Mathcad software environment. On the basis of a discrete transfer function, a scheme for computer modeling of the process of processing the signal of the instantaneous speed of rotation of the crankshaft by hardware is constructed. The output signal was obtained by computer simulation, as a result of the analysis of which the speed of the hardware for processing the input information was established.
A frequency-modulated instantaneous crankshaft speed signal is proposed as input information for monitoring the identity of the cylinder power of an internal combustion engine. Algorithmic software is based on solving a predefined system of linear algebraic equations with optimization of the solution based on the least-squares method. Frequency and time methods of signal measurement research are investigated. In the temporal representation, the system of algebraic equations is the balance between the values of the fluctuation signal of the first mass at specific points in time and the sum of the calculated contributions of the cylinders. The addition to the sum is determined by the product of the weights for the corresponding function of the contribution of the cylinder to the fluctuation signal. This function is calculated as the convolution interval between the torque of an individual cylinder and its transfer function. As a result of solving the system of equations, we obtain the weights of the cylinders, which are used to determine the distribution of cylinder power of the power unit. When comparing the methods, it was found that the time method of presentation provides better performance. A mathematical apparatus for estimating the maximum plausibility of the parameters of the determined components of the contributions of individual cylinders in the signal of fluctuations in the speed of rotation of the first mass of the crankshaft has been developed. An algorithm for estimating the weights of cylinders, which implements the correlation method of analysis, is also proposed. This provides a significant improvement in the signal-to-noise ratio in the measurement implementation of the signal of fluctuations in the speed of the crankshaft. An analytical expression for the cross-correlation function between the time realization of the fluctuation signal and the torque of the first cylinder is obtained. The scheme of the algorithm for monitoring of identity of cylindrical powers of the power unit is developed. The uncertainty of information technology for processing indirect measurement data is investigated and the requirements for metrological characteristics of hardware for measuring the signal of the instantaneous crankshaft speed signal are established.
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