EFFICIENT COMPUTATION OF THE SENSITIVITIES OF RECIPROCATING-ENGINE DYNAMICS TO DIMENSIONAL TOLERANCES

An efficient method has been developed to accurately and efficiently p redict the sensitivities of an internal combustion engine's steady-sta te outputs to dimensional tolerances. The alternating frequency/time ( AFT) domain technique is used to determine the steady state response ( mean crank speed, mean driving torque and Fourier-coefficients of temp oral variations in crank's speed and driving torque) of an engine, whi ch is governed by a nonlinear differential equation with discontinuous forcing function due to the nature of the pressure-volume (P-V) diagr am. The validity of this method has been established by comparison wit h the results from numerical integration of the differential equation of motion. This technique, by virtue of being computationally efficien t, is well suited for the development of an optimal tolerance allocati on scheme based on nonlinear programming. Copyright (C) 1996 Elsevier Science Ltd.