65 New Indicated Mean Effective Pressure Measuring Method and Its Applications

IMEP can be generally calculated by numerical integration on the PV diagram. However, this method requires a great number of sampled data per cycle, in order to ensure high accuracy in calculation. The present method is a to use only the primary and secondary components of engine speed from the pressure diagram based on the Fourier series. Owing to this method, calculation errors have become smaller than conventional method even though the number of samples is reduced, and calculation time is also reduced by the conventional method. Using present method, a Fourier series type combustion analyzing system has been developed. Real-time IMEP measurement is allowed in this system owing to the characteristic features described above, and the validity of calculated results is confirmed by comparing the results with the IMEP values obtained by batch processing through the numerical integration.