Two major problems with petrol/diesel cars are their inefficiency and emission of harmful of pollutants. In a bid to create environment-friendly cars that give better mileage, hybrid cars have been developed in recent years, the best known example being Toyota Prius. (See photo below.)
|Toyota Prius hybrid car|
The hybrid car has a conventional internal combustion engine and also an electric motor, providing secondary propulsion. The motor can switch its roles so as to be employed as generator for recharging batteries carried on board. In city driving, when clutch A (see diagram below) engages wheels, the petrol engine is automatically shut down and electric power takes over, enabling the car to cruise at speeds up to 30 kilometers per hour. For acceleration and highway cruising, the petrol engine gets restarted and clutch B connects it with wheels.
What is regenerative braking? And how does it work?
Most hybrid cars, including Toyota Prius, also use regenerative braking to top up the battery charge. In this system, when the driver brakes, the motor links up with wheels and becomes a generator. This causes kinetic energy of the wheels to be transferred to batteries via generator and helps the car to slow down. This in-car recharging eliminates the need for external recharging stations. Interestingly, in city driving such hybrid car gives better mileage than on a highway because in stop-and-go traffic the car’s regenerative braking recovers much of the spent energy. On average, a hybrid car is at least 60% more efficient in terms of fuel consumption than a standard model of similar size and weight.
Hybrid vehicle (Wikipedia)