Optimization of engine torque using variable valve actuation systems

Author: 
Gabriele Solarini Paviotti, Tarcisio Colombo (Alfa Romeo, Fiat GM Powertrain)

CHALLENGE - The aim of the work is the maximization of engine torque optimizing the Variable Valve Actuation Systems parameters: intake valve timing, exhaust valve timing and intake valve lift and opening duration. The VVA system is not present in the studied 3.2L, V6, GDI engine with double VVT (intake and exhaust). In the design phase, engine performance variation is studied to understand if the adding the VVA system could enhance torque.

SOLUTION -  In order to calculate the whole engine torque values different simulations have been performed at different engine speeds. A total of 15 values have been taken into account, ranging from 1000 to 7000 rpm. GT-Power has been used to model the engine considering the direct injection system with different values of spark advance, injection pressure, injection timing, combustion rate and A/F ratio. modeFRONTIER, with the GT-Power direct integration node, has been used to optimize the parameters at each engine speed using the Simplex algorithm considering torque as the only objective.

BENEFITS - The optimized engine configuration using the VVA system shows an increase of torque at each engine speed (1000-3000 rpm and 3000-5000 rpm in the VVA system). The efficient coupling between modeFRONTIER and GT-Power and the fast convergence of the Simplex algorithm allow to save a sensible amount of computational time and avoid a manual search.

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