Scientific paper ID 1483 : 2017/3

Abstract. Graphical charts representing the variance between the power of the engine and its torque regarding full load curve need to be drawn by specific mathematical expressions. This is d by applying the analytical approach during the calculation of the parameters of the traction speed characteristics of the automotive vehicles. Currently used mathematical relationships approximate with enough accuracy the variance of the power and torque in accordance with rpm of the crankshaft in cases when the charts are gradually changing convex curves that have no interruptions.

The modern automotive vehicles are equipped with internal combustion engines (ICE) with almost constant values of power and torque within a vast areas of variation of the revolutions of the crankshaft. In such a case applying the interpolation formulas to approximate the full load curve chart of a this type of ICE doesn’t provide the d accuracy. The paper offers a model to approximate the values of characteristics (effective power and torque) to available laboratory full load curve of an engine with a constant power at a certain frequency range. The model is applied to a specific full load curve of a particular engine. Through regression analysis are determined the coefficients of approximating polynomial and the mean square deviation. The results represent a good approximation to the real full loaf curve of the engine.