Research of dynamic phenomena in a model engine stand

Abstract

The highest loads on the elements of the crank–piston system of the internal combustion engine occur during the combustion phase which takes place successively in individual cylinders. Smaller, but also significant, loads occur beyond this phase when dynamic forces begin to play a dominant role. The latter depends on the degree of wear of the engine components. The aim of this article was to analyze the stresses in a model stand for testing dynamic phenomena in an internal combustion engine operating without the combustion process. A stand has been developed which includes a combustion engine driven by an electric motor placed on a mobile frame. The coast-down method was used to estimate the average values of the equivalent moment of inertia of the engine for various cylinder configurations with a lack of compression process due to a significant weakening of the valve springs or significant wear of the valve seats. This lack of compression was simulated on a bench by partially loosening the spark plug mounting. The article presents the values of the determined mean values of the equivalent moment of inertia of the engine and the stress values in the stand frame obtained from its model developed with the use of the finite element method. The obtained values were important from the point of view of the engine dynamics simulation process outside the combustion area and the safe foundation and operation of the stand frame during the experimental tests.