ENGINE PERFORMANCE MAPS IN NONSTATIONARY OPERATING CONDITIONS OF CAR ENGINE

A method is proposed in the paper to calculate effective efficiency of an engine in nonstationary operating conditions. A reference point for this method is the effective efficiency of the engine derived from its performance map. A research methodology has been developed to this end, the basis of which consists of measurements and calculations of the total energy efficiency of a car motion in a variable driving cycle. In order to determine the impact of the road grade, measurements were performed along a geodetically described road section in two traffic directions:”up ” and “down”. The adopted research scheme allows covering the area of the engine performance map being of interest to us with measuring points. The mean value or rotational speed and its change in unit of time were adopted as the leading parameters which have a dominating influence on, and result in a reduction of the effective efficiency of the engine. To improve the accuracy of calculations, the variable driving cycle consists of driving phases and idle running. The volume of fuel consumed, not accounted for in the driving phases, being the difference between the calculated and consumed fuel, is a measure of reduction of the effective efficiency of the engine, whilst the unit power of additional motion resistance of the vehicle (a*v) is a leading parameter in the analyses of the calculation results