Stochastic model of the process of starting piston combustion engines and the practical use of the process

The paper presents a proposal of a model of diesel engine starting process as semi-Markov process. States of the process are the following: cold engine state (s1), warm engine state (s2) and hot engine state (s3). Idea of using the model for determining a quantity of harmful substances emitted in exhaust gases during starting of engine, has also been proposed herein. The paper provides a possibility of considering in researches on the quantity of harmful substances contained in exhaust gases, a mass of harmful substances as a random variable. It has been accepted that statistics of the random variable has distribution asymptotically normal. The stochastic model of self-ignition engines starting process enables deriving the limiting distribution of the process, being the probabilities of occurring the mentioned states (s1), (s2) and (s3) one by one. The distribution is indispensable to determine the expected value of the mass of harmful substances emitted in time of successive re-starts of engine performed during long operation. The second approach to estimation of the mentioned mass considered as a random variable enables estimating its expected value in time of long-term work of engines till the first failure or in the period between two successive preventive maintenances. The paper proposes the interval estimation because makes it possible to assess accuracy of the estimation. In this case the mentioned value is determined in the form of interval with random edges (limits), which comprises unknown value of the mass of harmful substances emitted by engine, at the probability called confidence level.