Efficient technique for computing the sensitivities of reciprocating engine dynamics to dimensional tolerances

An efficient method has been developed to determine the steady stat response of an internal combustion engine, which is governed by an nonlinear differential equation with discontinuous forcing function due to the nature of the pressure-volume (P-V) diagram. Unlike previously reported methods for dynamically driven mechanical systems, this approach can accurately and efficiently predict the sensitivities of an engine's output to dimensional tolerances. Hence, this technique is well suited for the development of an optimal tolerance allocation scheme based on nonlinear programming. The validity of the method which is based on the alternating frequency/ time (AFT) domain techniques has been established by comparison with results from numerical integration of differential equation of motion This method directly yields the mean crank speed and Fourier coefficients of temporal variations in engine's outputs such as crank's speed and the driving torque.