Cycle-by-cycle estimation of IMEP and peak pressure using crankshaft speed measurements

Abstract

Cylinder pressure based control of internal combustion (IC) engine uses variables derived from cylinder pressure trace as a feedback input to the engine control and diagnostic systems. Direct measurement of such variables using cylinder pressure sensor is quite expensive. This paper proposes an ind irect method of estimating two of such variables namely peak pressure (PP) and indicated mean effective pressure (IMEP) using crankshaft speed measurements. Discrete Fourier Transformation (DFT) is used to transform crankshaft speed fluctuation in time domain to frequency domain. Real and imaginary parts of frequency domain signal, at different harmonics of engine firing frequency, are used as input to multilayer perceptron (MLP). The output being PP and IMEP. Various combinations of inputs starting from signals at first harmonic to signals at first five harmonics are tested. Training and validation of MLP is done using data generated on a test rig consisting of single cylinder engine with eddy current dynamometer. The results show that the MLP is suitable for estimation of cycle-by-cycle values of PP and IMEP for most of the operating points where cyclic variations are within driveability limits.