Toyota Prius

The Toyota Prius is a Automobile with hybrid Motorisation gasoline-electricity, but with single primary energy, the gasoline. First model (standard NHW10) was proposed in 1997 in Japan only. It was followed by a technically altered version but to the identical body (NHW11) in 2000, available then also in Europe, with the the United States and in Australia. The current model (NHW20) was introduced fine 2003 in Japan and the USA, and at the beginning of 2004 in Europe. It marks the access of this car to a real popularity, in particular with the the United States.

The present generation, called Prius II, is a functional vehicle with 5 doors and 5 places (Prius I, 1997-2003, was a truck 4 doors with a separate trunk) intended to return in direct competition with the conventional vehicles of the family category and which thus does not sacrifice the performances (autonomy, speed, acceleration, habitability). The approval of control downtown is remarkable and its sobriety (less than 5 L downtown and suburbs) becomes exceptional… in the obstructions, but not only: it is indeed on road at reasonable speed that this type of motorization allows the greatest savings in fuel.

Technical description

The concept combines a Petrol engine which under-would be dimensioned (57 kw - 77 CH) if it were used, only optimized for low fuel consumption and a limited pollution (driving with Cycle Miller/Atkinson where the Taux of relaxation is higher than the Ratio compression), and two electric engine-generators (called MG1 and MG2, of different sizes and powers), all three connected to a Epicyclic gear. The unit constitutes an electromechanical transmission (part of the power passes by mechanical way, the other by electric way) reproducing the feelings of conduit of a transmission with traditional continuous variation, although based on a completely different principle. Such a transmission does not comprise in particular any Embrayage or mechanical device of decoupling between engines and wheels, become useless.

Although functioning only with the gasoline like primary source of energy, the hybrid motorization of Prius manages very significantly to lower consumption compared to that of a car equivalent not-hybrid. This result is obtained while making function the Thermal engine more close possible of its best performance, which is impossible on a traditional car because of the very important fluctuations of power related to control.

On an hybrid on the other hand, it is possible to only use the electric propulsion with very low power (where the thermal engine would have a very weak output), as long as the battery is not discharged, or contrary to helping the Thermal engine by the supplement of a Electrical motor at the time of the important needs for power (accelerations, strong coasts…). In mode of cruising, the thermal engine generally functions with a load slightly higher than necessary and uses this surplus of mechanical energy to charge the battery. The output of the quickly increasing engine with weak load, this surplus of energy is almost free.

To final, the operation much more regular of the thermal engine also leads to less a Pollution and a less mechanical wear. Moreover, the reversible character of the electric engine-generators makes it possible to recover with braking part of the kinetic energy of the car, via MG2 which is directly related to the wheels. This characteristic is particularly made profitable in urban circulation, where Prius excels on the plan of the output compared to the cars with purely thermal propulsion.

The control system - named HSD (Hybrid Synergy Drive) in the version 2004, THS previously - organizes the distribution of the efforts between the thermal engine and the 2 electric engine-generators to optimize the total output. Contrary to a spread opinion, the electric part is always requested whatever the type of control, but not necessarily the battery, electricity being able to pass directly from MG1 to MG2 or conversely; it is the principle even of an electromechanical transmission which makes it possible to multiply or divide the couple with the wheels as a mechanical Gear box would do it, but by electric way.

In order to be able to recover energy with the decelerations, braking is him also hybrid and controlled by computer: as soon as the accelerator is slackened, the thermal engine is not supplied any more while carburizing (it stops physically below approximately 70 km/h) and the driving Frein is ensured by MG2 which benefits from it to reload the battery (regenerative Freinage). In the same way, when one actuates the pedal of Frein, it is initially MG2 which provides the braking force before letting operate traditional discs when the pressure increases. Although the power of MG2 is of 50 kw, the electric power of braking is limited by the power of load which the battery (21 kw according to the manufacturer) can support, which encourages the driver to carry out soft brakings to recover the maximum of energy and to thus lower its consumption.

Model 2004

Lengthened of 13,5 cm to reach 445 cm, from which 15 cm rise from an increase in the footing, the Prius news gains of habitability with the back and offers a trunk of 408 liters on the whole, including/understanding a filing space of 41 liters under floor. Its Cx of 0,26 give him a fluid line having remote resemblances to that of the Citroen GSA or, more close to us, the Audi A2. The disadvantage of such an aerodynamic form (Windshield very plunging in particular) resides, as on many modern cars, in a low visibility with the four angles.

The request largely exceeding the offer, the production was doubled for 2005 to reach: 100000 specimens. At the USA, its preferential market, it is sold approximately: 8000 with: 10000 Prius per month since the beginning of the year 2005. The worldwide production of Prius (all confused generations) exceeded the bar of: 500000 specimens at the end of April 2006 according to Toyota. Prius is proposed with: 25550 € in France (price catalogs, not taking account of possible handing-over of Toyota), where five hundred specimens were available in 2004, this number having been carried to: 2500 in 2005. It then gave right to a tax credit of: 1524 €. Since January 2006, this tax credit was carried to: 2000 € in order to encourage energy saving.

She was elected Voiture of the Year 2005 in Europe.

External bonds

the meeting of impassioned of Prius, non-profit-making: Prius Touring Club
the Community site Wiki for impassioned of Prius: http://prius.ploki.info

- Commercial links:

Official site of Toyota Prius
the site of Toyota on the " Hybrid Synergy Drive"
the site of Toyota on the " Hybrid Synergy Drive"
Green Because Congress sales of Prius and other hybrids in the USA at December 6th, 2006.

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