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Technical Paper

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.
Technical Paper

Development of a Rapid Compression-Expansion Machine to Simulate Combustion in Diesel Engines

A rapid compression-expansion machine which can simulate the combustion processes in diesel engines is developed. The configuration of the combustion chamber is a 100 mm bore and a 90 mm stroke, and the compression ratio is 15. The piston is driven by an electro-hydraulic system with a thrust of 90 kN and the maximum frequency of 20 Hz. The whole system composed of a hydraulic actuator, a fuel injection system, and a valve driving unit is sequentially controlled by a computer. The reproducibility of the stop position of the piston at the end of compression is achieved with an accuracy of ±0.1 mm by employing a hydraulic-mechanical brake mechanism. The experiment shows that the combustion in the expansion stroke is achieved, and that the combustion characteristics such as the rate of heat release and indicated output as well as the exhaust emission can be measured.