Unsteady angular speed of diesel engine crankshaft preliminary examination

The paper discusses issues related to measurement of unsteady angular speed of diesel engine crankshaft. The focus is on the selection and optimization of the measuring method to obtain high accuracy, eliminating errors resulting from the unsteady angular speed of markers on diesel engine crankshaft. A method that uses a counter markers placed on the engine flywheel had been worked out. Markers location has been read out by two slit optical sensors. Number of markers and the distance between the sensors were chosen so as to counter tooth during the transition between the sensors count the more than 10,000 pulses at rated speed of the shaft. This provided a measurement method resolution at 0.01 %. Initial studies were performed on one-cylinder diesel engine with the greatest unsteady of angular speed. Additionally analysis which treated the measured unsteady angular speed of diesel engine crankshaft as a deforming pressure mapping as a function of the calculated piston movement was performed. This deformation is caused by the assumption that a constant rotation speed is proportional to time, and measurements are made at a constant rate. In the case of synchronized measurements of PLL circuits duplicating markers on the shaft against the expectations the deformations due to the activity of the follow-up mode of such systems are increased. The influence of these deformations on the designation of an average error of cylinder indicated pressure and other parameters obtained from the analysis of the pressure and vibration envelope has been examined.