Descrizione del funzionamento dell'automobile elettrica: tesina d'inglese (3 pagine formato doc)
L'AUTOMOBILE ELETTRICA: TESINA
Electric car. An electric car is a vehicle powered by an electric motor which runs on a system of rechargeable batteries.(These are at present of the lead-acid variety, although new types, including zinc-chlorine, sodium-sulphur and fuel cells, are being developed.) The motor converts the battery’s electrical energy into kinetic energy. The driver simply switches on the power, selects “Forward” or “Reverse”, and steps on the accelerator pedal.
Like gasoline-powered cars, electric vehicles have a system of gears, shafts, and joints to transmit motion from the motor to the car wheels. However, they do not have clutches or multi-speed transmission. In order to go backwards, the flow of electricity through the motor is reversed, changing the rotation of the motor and causing the power train to make the wheels reverse direction. Moreover, they do not have the high number of moving parts that an internal-combustion engine has, since the electric motor has only a single rotating element.
MACCHINE ELETTRICHE, TESINA
In most electric cars, the braking system acts as a battery charger. When drivers take their feet off the accelerator, the motor acts as a generator, converting the energy produced by the movement of the vehicle back into electricity and storing it in the battery. This conversion of kinetic energy into electric energy slows the car. To stop the car quickly, however, there is also a brake pedal and a traditional braking system which works on the wheels.
In the early days of automobiles, electric cars were serious rivals to gasoline cars. The first automobile to exceed 100 km an hour was an electric car (Camille Janatzy’s La Jamais Contente, 1899). In 1900, 40% of U.S. cars were powered by steam, 38% by electricity and only 22% by gasoline (petrol). The gasoline car was unreliable and noisy. Moreover, it had to be started by hand crank, and this made it difficult to operate. The electric car, on the other hand, was silent, self-starting and needed minimal maintenance, but it was limited by its short range (50-60 km) and its dependence on recharging equipment. Eventually, it was another application of battery power, the electric self-starter, that helped to make the gasoline car more attractive, especially for women motorists.
TESINA SVOLTA SULL'AUTOMOBILE
Electric cars began to reappear in the 1960s as an answer to problems of air pollution in city centres, and in the 1970s, as a result of oil shortages. Since then, several car manufactures (Ford, Nissan, Volkswagen) have included electric cars in their range. More recently, in 1996, General Motors Corporation announced the first modern, mass-produced car designed specifically as an electric car (until then, electric cars were generally created by replacing the gasoline engines and fuel tanks of conventional cars with electric motors and batteries).