Study of uncertainties of cylinder power monitoring based on computer simulation

Abstract

It is shown that the known methods and hardware and software tools for monitoring the cylinder capacities of internal combustion engines require manual labour. With a sufficiently large number of power unit cylinders and the absence of output electrical signals from the primary pressure transducers, the speed of operation of this method of monitoring cylinder capacities is significantly limited. Emphasis is placed on its use as a signal of measurement information for uneven rotation of the crankshaft of the internal combustion engine. Algorithmic support for monitoring the distribution of cylinder powers implements the principle of deviation control and is reduced to the solution of a redefined system of linear differential equations of the second order, the number of which determines the number of cylinders. The Laplace transform under zero initial conditions was used to solve the deterministic system of linear algebraic equations. The information links between the measurement information signal and the torques of individual cylinders in the form of transfer functions have been established. Sources of random malfunctions of hardware and software were analysed. It was established that the first component of hardware uncertainty has a multiplicative nature, and the second and third components have an additive nature. Also, the difference between them is that the first and second uncertainties act at the input of the computer system, and the third at its output. The hardware operates with sequences of pulse signals, which in mathematical representation are considered as a sum of individual pulses. A linear random process, presented as a stochastic integral, is used to describe the thermal disturbances of hardware. The Monte Carlo method was used as a mathematical tool for the computer simulation of random disturbances. Calculating the insensitivity bands around the nominal characteristics of the component conversion is performed based on summing up the uncertainties of the input signals and disturbances. When developing it, it was assumed that all components of the input signals' uncertainties are random variables specified by their one-dimensional and multidimensional distribution laws. The Lamer scheme, the standard algorithm for determining the speed of building numbers for a given period of the maximum length of a series, and the algorithm for modelling random numbers were also used. The requirements for the measurement uncertainty of the irregularity signal of the crankshaft rotation of the internal combustion engine have been established.