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Examinations of effective efficiency of a car engine in non-stationary work conditions from torque load

Ubysz A.

Journal of KONES

2009

Vol. 16, No. 4

463-468

Measuring method and calculations of the impact of non-stationary work conditions of car engine torque load upon its effective efficiency have been presented in the paper. The obtained results have been compared to the already achieved results. The applied method of calculation balance and the consumed fuel enabled the writer of the paper to calculate the value of the change of unitary fuel consumption at a work point on engine performance map. The carried out examinations focus on measurements at one measuring length and so the rate of torque load at each of the four gear box ratio (2-5) can be controlled by constant final velocity of driving or by shifting or extending the measuring length against the lowest point ( the measuring length is 'U'-shaped). Finding the right solution to this problem will allow elaborating the calculation algorithm of engine effective efficiency for the examined range of engine performance maps for changeable, non-stationary work conditions. The results make it ąuite explicit that non-stationary work conditions from the engine speed and the engine load impair the effective efficiency of the engine at work in particular gears. Non-stationary mode of engine operation is essential for the higher values of gear box ratio whereas for lower values the engine load really matters.

Engine performance maps in nonstationary operating conditions of car engine

Ubysz A.

Journal of KONES

2009

Vol. 16, No. 3

455-463

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 to tal 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 roadsection 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 oftime 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*ni) is a leading parameter in the analyses of the calculation results.