On-Line Cylinder Diagnostics on Combustion Engines by Noncontact Torque and Speed Measurements

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.