Improvements in or relating to methods of and apparatuses for indicating a predetermined position of a piston or crankshaft of a piston engine.

摘要

In order to determine the top dead centre position of a piston (11) and crankshaft, a transducer (10) directs an ultrasonic beam into one of the cylinders at a position intermediate the ends of the piston stroke. When the piston or a piston ring passes into or out of the ultrasonic beam, the level of signals reflected or transmitted to a transducer (10) or (10 min ), respectively, changes and provides first andsecond signals. A further transducer (8) produces third signals corresponding to rotary positions of the crankshaft and flywheel (3). A processor (9) processes the first, second, and third signals and indicates the position of the flywheel (3) corresponding to top dead centre of the piston (11).