A Compensating Method for Zero Drift of Indicator Diagram Recorded by Piezoelectric Pressure Transducer

Abstract

Piezoelectric pressure transducer have been used to get an indicator diagram in engine experiments. In these experiments errors, which are caused by miss-setting of TDC mark, integrating coefficient of charge amplifier, thermal distortion fo pressure diaphragm of the transducer and zero drift, make it very difficult to analyze indicator diagram exactly. The authors derived an equation of a pressure drop at inlet and exhaust valves of 4 stroke cycle gasoline engines as a function of engine parameters, with the result of thermal analysis of these drops. This equation enables us to estimate the pressure drop and to compensate zero drift of an indicator diagram.