A New Method for Monitoring Thermal Energy Utilisation of Vehicle Engines 931140
Proposals for a new method for measuring the fuel efficiency of engines in situ in vehicles are based on a new electronic instrument, the Ergometer, which measures the cumulative work energy delivered by an engine over a complex journey.
Engine thermal efficiency varies widely with load, speed, steady and transient operations. Measurement of EJATE, or Elapsed Journey Average Thermal Efficiency, derived from work and fuel measurements, gives clearer information on the state of development of a given vehicle's power train to meet economical driving conditions. Such information is considerably more revealing than conventional vehicle fuel consumption measurements.
The Ergometer can be fitted to individual vehicles, or to engine test beds. Most attractively it can be fitted to rolling road dynamometers where the EJATE of any vehicle can be easily measured.
The paper describes some EJATE test measurements undertaken for five journeys on one vehicle as well as the basic principle and construction of the *Ergometer work measuring instrument.