Pressure measurement by Piezo-electric transducers in reciprocating combustion engines

The properties, use and construction of quartz Piezo electric transducers are briefly described. The dynamic calibration of quartz pressure transducers have been investigated using a Balanced-Disc pressure pick-up as a standard. The temperature effect on the static and dynamic output of these transducers has also been examined. Various types of engine indicators and their limitations are discussed. Piezo-electric pressure transducers and strain gauges were used for constructing an inertia-free pressure-volume indicator to produce a P-V diagram on an oscilloscope screen from which the trace was recorded. This included a simple and accurate method for obtaining top-dead-centre on pressure-time records. Some aspects of diesel combustion were considered using P-T diagrams from a variable compression Lister F.R.I diesel engine running at different loads and compression ratios. The effect of the shape of transducer passage on the accuracy of P-T diagrams is observed. Volumetric efficiency was measured using a crystal pressure transducer. The assumptions of this method was checked by comparison with the volumetric efficiency obtained by. two other established methods.