Ring Motion Modeling and Measurement A combination of computer analyses, real-time oil consumption calculations, and blowby measurements is used to determine the cause of excessive oil consumption, blowby, and ring wear. The models provide new understanding of piston ring motion characteristics and facilitate design optimization for minimum oil consumption and blowby. Test piston is fitted with special electrically insulated ring grooves and a radio transmitter to monitor ring motion. Ring motion measurement techniques, with telemetry similar to that utilized in piston temperature measurement, are used to supplement analyses. The key component is the power generator, which uses piston acceleration forces to move a steel slug through a magnetic field, generating alternating current.
Power is rectified and filtered to supply transmitter and sensor circuitry.
Capacitive sensors are multiplexed to an oscillator that transmits temperature data as an RF signal to an antenna in the engine sump. The resulting package, which has been tested at temperatures to 600 degrees F and engine speeds in excess of 5,000 rpm, is small, lightweight, and non-intrusive. A piston is instrumented to measure seven temperatures simultaneously in a turbocharged engine. Continuous measurement of sulfur dioxide in the exhaust allows calculation of the oil consumption rate, and special sampling procedures are used to differentiate burned and unburned fractions. The sulfur tracer technique replaces time-consuming oil weighing procedures.