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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.

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.

The U.S. Army, having a large fleet of military vehicles, must manage the periodic overhaul and testing of its equipment, inclusive of the constituent diesel engines. Because of the world wide fleet distribution, the limited quantities of engines, re-manufactured at any one location, would seem to preclude having sophisticated automated dynamometer test cells for the final overhauled engine inspection. However, the other depot engine test requirements, which include powerpack testing both separately and as installed in overhauled vehicles, provide sufficient justification for a combined development of a Universal Depot Inspection System (UDIS). The primary function of UDIS is to automate and control engine dynamometer testing; however, the UDIS modular design allows the multi-function components to be utilized in various combinations to perform the other depot test operations.