Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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System for vehicle propulsion

Energy recoveryFlexible power-trainHybrid systems


The invention concerns a power split system for electric-thermal hybrid propulsion with a gearbox and single electric motor or electric propulsion with double motor and speed coupling. In the first case, the objective is the recovery of kinetic vehicle energy, during deceleration and braking phases, and the purely mechanical, electric, or combined traction. In the second case, flexible management of the rotation speed of the two electric motors is possible.

Technical features

The system is based on the interposition of a planetary gear set between the internal combustion engine and the gearbox. The planetary gear set is connected to an electric motor-generator and equipped with a braking module (active or passive) arranged in an axis with one of the gear wheels.

The single motor-generator, through the activation of the braking module, can be used for vehicle starting, gear shifting, regenerative braking, battery recharging, heat engine downspeeding and pure electric running. The brake is particularly active during strong deceleration, where it allows the motor-generator to regenerate with high torques. The system can also be used in battery and/or fuel cell propulsion with a double electric traction motor, where the planetary gear set would allow the rotation speed of the two motors independently of the forward speed of the vehicle, while the braking module would allow the torque applied to one of the two electric motors to be flexibly increased.

Possible Applications

  • Automotive industry;
  • Heavy transport.


  • Flexible hybrid propulsion (thermal/electric or combined) without the need to completely redesign of the heat engine and / or the transmission with a single electric motor;
  • Efficiency increasing for propulsion with renewable or synthetic fuels through downspeeding of the heat engine and energy recovering during deceleration phases;
  • Optimization of electric propulsion in battery and/or fuel-cell vehicles.