Search Results

The flywheel speed is recorded during snap acceleration, while operating the engine without external load and at fully open throttle. A non-contacting magnetic sensor at the engine flywheel detects the instantaneous speed. A digital circuit, which includes a microprocessor, samples and processes the speed data. The speed increment observed over a fixed number of engine cycles is a measure of the engine torque. Since the instantaneous flywheel speed exhibits significant variations, the speed increment is determined on the basis of a linear regression analysis of the speed waveform. The approach was verified experimentally on eight-cylinder Diesel engines. The results from the snap acceleration analysis were found to be consistent with dynamometer measurements within mean relative error margins below four percent.

Many internal combustion engines are equipped with a vibration damper attached to the front. Excessive thermal loads on the viscous damping element occasionally lead to damper failure, which in turn causes excessive torsional oscillation amplitudes in the crankshaft, and subsequent damage to the engine if the damper failure is not recognized immediately. Two non-contacting magnetic sensors at the engine front and flywheel detect the speed at both locations, and the torsional crankshaft strain. A digital circuit, which includes a microprocessor, samples and processes the raw engine speed speed data. The transducer concept provides for stable operation independent of motor speed and varying ambient temperatures. Experimental data were recorded on an eight-cylinder Diesel engine with and without damper. The measurements, made under steady state operating conditions, show that the speed oscillation amplitudes at the engine front more than double when the damper fails.

Crankshafts are subjected to complex forces and torques which vary continuously with location and time. A nonlinear crankshaft dynamics model is developed on the basis of a dynamic simulation language. The model comprises compression and combustion forces, dynamics of oscillating parts, spatially distributed inertial and elastic effects on the crankshaft, and dissipative effects. The model is validated through experimental records of crankshaft torsional dynamics on an eight cylinder Diesel engine, comprising wide ranges of engine torsional loads and speeds. The analysis of crankshaft dynamics allows to determine the computational requirements for the determination of the instantaneous engine torque. Such instantaneous torque measurement is of interest for improved performance and emission control.

This paper describes a nonintrusive transducer for the measurement of crankshaft torque and speed on internal-combustion engines. The transducer is added to an existing drive train without requiring drive train modifications. Two non-contacting encoder-magnetic pickup combinations detect the phase angle between the pulse trains, which is a measure of the engine torque. A digital circuit, which includes a microprocessor, samples and processes the raw torque data. The concept provides for stable transducer operation independent of motor speed and varying ambient temperatures. The results from experiments on an eight-cylinder Diesel engine demonstrate that crankshaft torque and speed variations are detected with high resolution and detail, permitting on-line diagnostics including fault detection on individual cylinders.