Toyota Prius hybrid 1997-2009 - First Generations
Toyota decided to initiate the Twenty First Century with a new propulsion system aimed at reducing fuel consumption and emissions with a car offering all the convenience and driving pleasure of a conventional gasoline engine sedan. The Toyota Prius development work was started in early 1990's under the code name G21. The idea of creating a hybrid system comes from the desire to combine the best of the electric motor and internal combustion engine. Electric drive provide above 90% energy efficiency but the battery energy storage is heavy and allows limited range for a long lasting charging time. The charging of an electric car requires electric filling station network not available at the time. The internal combustion engine has been around for more than a century and maintenance garages as well as fuel filling stations are plentifull. There are two types of hybrid systems: in a 'series hybrid' the engine drives a generator and power created is used by a motor to drive the vehicle's wheels. In a 'parallel hybrid system' the drive forces from the engine and electric motor drive the wheels separately. Toyota developed the THS (Toyota Hybrid System) combining both systems to maximize the advantages. Further fuel efficiency gains and reduced emissions are achieved by the engine's "stop and go" strategy and energy recovery under braking. The power unit works in conjunction with a bank of advanced nickel-metal hydride batteries which form an energy buffer. Because they are maintained in a constant state of charge by the Toyota Hybrid System, they never need external recharging. The various mechanical elements of the Toyota Hybrid System are connected by a power splitting device, in the form of an epicyclic gear train, which enables the engine output to be divided between driving the wheels and turning the electric generator. The key to the mechanical efficiency of Toyota Hybrid System is the electronic control of power flow between the mechanical and electrical elements to ensure that energy consumption is optimized at all times.
The Toyota Prius can run on either its gasoline engine, its electric motor, or a combination of both. The ratio of power provided by each system is constantly monitored electronically, depending on speed and load, to keep the car in its most efficient operating mode. The Toyota Hybrid System allows the Prius to run on electric power alone; under selected driving conditions the Prius gasoline engine shuts off completely and the electric motor takes over. As a result, in many high density traffic situations, the Prius is totally emission-free. The main function of the gasoline engine is to drive the wheel but any excess output is used to recharge the batteries. The batteries are also charged by regenerative braking. In turn, the batteries supply extra power, via the electric drive motor, when required such as for hill climbing or overtaking. In particular situations where the gasoline engine cannot run efficiently, or where it would produce relatively high emissions for example at low speed, travelling downhill or when standing still at traffic light it is switched off altogether. Starting from rest is normally accomplished in electric drive only. The gasoline engine is starting as the Prius picks up speed.
The Toyota Prius was launched on the Japanese market in 1997 and in the United States and Europe in 2000. The Toyota Prius first generation was announced with a fuel consumption of 5,1 litre per 100 kilometre and a CO2 emission of 120 g/km. 130.000 units of the Toyota Prius first generation were sold. In 2003 Toyota launched the second generation of the Toyota Prius with a wider cabin, a new modern and specific styling and a more powerful propulsion system. The fuel consumption was announced at 4,2 litre per 100 kilometre and CO2 emission at 102 g/km. The second generation Prius has 1,5 times greater electric motor power (50 kW- 68hp) and 8% more petrol power (57 kW - 78 hp) allowing an increase in the usage ratio of the electric motor for improved efficiency.
In 2009, worldwide sales of Toyota Prius since is first introduction, exceeds 1,2 million units. Sales have been picking up slowly with 323 units in 1997 and 17.653 units in 1998 or 15.243 units in 1999 for the Japanese market exclusively. In 2000, Sales of the Toyota Prius was extended to North American and European markets. Global sales evolved to 19.011 units in 2000, 29.459 units in 2001, 28.083 units in 2002, 43.162 units in 2003, 125.742 units in 2004, 175.157 units in 2005, 185.589 units in 2006, 281.265 units in 2007 and 285.676 units in 2008.
Texte Paul Damiens - Photos, technical illustrations Toyota
wallpaper of the Toyota Prius hybrid 1997-2009 click to enlarge