A hybrid vehicle comprises an internal combustion engine, which transmits power to the driving wheels by means of a transmission provided with a gearbox, and at least one electric machine which is electrically connected to an electric storage system and mechanically connected to the driving wheels.
The following is possible while traveling: either a thermal working mode, in which the torque is generated only by the combustion engine and the electric machine possibly acts as a generator for recharging the electric storage system; or an electric working mode, in which the internal combustion engine is off and the torque is generated only by the electric machine working as a motor; or by a combined working mode, in which the torque is generated both by the combustion engine and by the electric machine working as a motor. Furthermore, in order to increase the overall energy efficiency during all deceleration steps, the electric machine may be used as a generator for carrying out a regenerative deceleration in which the kinetic energy possessed by the vehicle is partially converted into electric energy, which is stored in the electric storage system, instead of being fully dissipated in frictions.
The arrangement of the electric machine within the vehicle and thus the mechanical connection of the electric machine to the driving wheels may be very complex in an existing vehicle, as in an existing vehicle which was not specifically designed for hybrid traction, finding the space required for accommodating the electric machine is generally very difficult. Therefore, modifying an existing vehicle to make the vehicle itself hybrid is often impossible; such a limitation is particularly serious, because it does not allow to produce a hybrid vehicle from an existing vehicle of conventional type, but requires a completely new design of the hybrid vehicle. Therefore, the design and development costs of a hybrid vehicle are often very high, thus making the hybrid vehicle marketing not so profitable.
US2005139035A1, US2002033059A1, US2008142283A1, DE102005004207A1 and DE102006059664A1, which are incorporated herein by reference in their entireties, describe a double clutch transmission for a hybrid vehicle, wherein one of the two primary shafts of the double clutch transmission is angularly integral with the rotor of a reversible electric machine.
EP1097831A2, which is incorporated herein in its entirety, describes a road vehicle with hybrid propulsion including: a couple of driving wheels; a thermal internal combustion engine; a gearbox provided with a primary shaft, a first clutch interposed between the thermal internal combustion engine and the primary shaft, a secondary shaft constantly meshing with the driving wheels, and a plurality of couples of gears, each of which defines a respective speed and comprises a primary gear mounted to a primary shaft and a secondary gear which is mounted to the secondary shaft and constantly meshes with the primary gear; a reversible electric machine having a shaft, which is connected to the primary shaft of the gearbox; and an auxiliary mechanism provided with a rotatably mounted shaft which takes the movement from the primary shaft.