Multiple-speed gearboxes with computer controlled automatic gear selection devices are a common possible choice in cars. Robotized gear insertion of one tenth of a second is possible. Economical and weight consideration are to be made to verify if it is convenient to use a smaller engine and a larger gearbox with a wider choice of speeds. In this paper, an automotive application for a public transport vehicle based on a Class S chassis with the choice of common-rail direct injection engines. This choice is particular unfavorable for the multispeed gearbox since common-rail engines have very flat specific fuel consumption curves. The lumped mass model implemented is conceived to estimate velocity, acceleration and fuel consumption starting from aerodynamic, inertia and thermodynamic data of the vehicle. The estimated data of performance and fuel consumption were compared with measured values. A Genetic elitarian Algorithm (GA) was used to optimise the engine choice and the gearbox speeds distribution. A maximum reduction of 15% was then calculated with a 16-speeds gearbox and a 140 HP/300Nm engine in comparison with the standard 5-speeds 204 HP/500Nm engine. This fuel reduction was obtained on the mixed city-motorway cycle. In this case, maximum speed is limited to 180km/h and the 0-100km/h acceleration is reduced to 11s (from the original 8.6s). The weight remains almost unaltered since the 204 HP engine is heavier than the 140 HP and this largely compensates the gearbox weight increase. The multiple speed solution seems to be very interesting also for public transports vehicles and for trucks. © 2015 Pushpa Publishing House, Allahabad, India.
Fuel consumption reduction and power downsize via robotized multiple speed gearbox and automatic selection system for an automotive application
PIANCASTELLI, LUCA;FRIZZIERO, LEONARDO
2015
Abstract
Multiple-speed gearboxes with computer controlled automatic gear selection devices are a common possible choice in cars. Robotized gear insertion of one tenth of a second is possible. Economical and weight consideration are to be made to verify if it is convenient to use a smaller engine and a larger gearbox with a wider choice of speeds. In this paper, an automotive application for a public transport vehicle based on a Class S chassis with the choice of common-rail direct injection engines. This choice is particular unfavorable for the multispeed gearbox since common-rail engines have very flat specific fuel consumption curves. The lumped mass model implemented is conceived to estimate velocity, acceleration and fuel consumption starting from aerodynamic, inertia and thermodynamic data of the vehicle. The estimated data of performance and fuel consumption were compared with measured values. A Genetic elitarian Algorithm (GA) was used to optimise the engine choice and the gearbox speeds distribution. A maximum reduction of 15% was then calculated with a 16-speeds gearbox and a 140 HP/300Nm engine in comparison with the standard 5-speeds 204 HP/500Nm engine. This fuel reduction was obtained on the mixed city-motorway cycle. In this case, maximum speed is limited to 180km/h and the 0-100km/h acceleration is reduced to 11s (from the original 8.6s). The weight remains almost unaltered since the 204 HP engine is heavier than the 140 HP and this largely compensates the gearbox weight increase. The multiple speed solution seems to be very interesting also for public transports vehicles and for trucks. © 2015 Pushpa Publishing House, Allahabad, India.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
