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General Distinctions
The key components of HEVs include:
Internal Combustion (IC) engine
Electric motor
Transmission
Energy management system
Fuel tank
Battery pack
In Honda's Insight and Civic hybrid, and in the Toyota Prius, the IC engine (1) and the electric motor (2) are connected to the wheels by the transmission (3). The energy management system (4) determines which motor to use and when to store electricity in the battery (6). The electricity stored in the battery pack (6) and gas stored in the fuel tank (5) provide the energy of a typical HEV.
The equipment on hybrid cars is similar to that on standard cars save a few differences.
Gas engine: The internal combustion gasoline engine on a hybrid is smaller and runs more efficiently than non-hybrids.
Electric motor: The electric motor on hybrids draws energy from a battery and also acts as a generator. As a motor it powers the car, as a generator it restores energy to the batteries.
Although the existing hybrids have smaller engines than conventional cars, the extra boost for comparable power comes from the electric motor, thus relying less on the gas motor and thereby increasing fuel economy and lowering pollutants. HEVs also convert energy normally wasted when the car coasts or brakes into electricity that gets stored in the battery until utilized by the electric motor.
In addition, some of the hybrid cars use unique tires that are stiffer and filled to a higher air pressure than non-hybrids for greater efficiency, less drag and increased mileage. When the hybrid SUVs hit the market in late 2004, it's highly unlikely they will be demonstrating the exceptional mileage of the first, smaller HEVs. However, they will have better fuel economy than their conventional counterparts as well as other technological advances.
Specific Distinctions
Each of the existing manufacturer's hybrids has their own unique elements that set them apart. In the Toyota Prius, because an electronically-controlled power splitter, managed by the car's computer directs power from the engine to both the wheels and the generator allowing either the IC engine or electric motor to run alone or together, it can maintain its optimum speed and range. As a matter of record, the Prius's maximum speed is claimed to be 100 mph, while it can go from 0-60 mph in 12.7 seconds, and at freeway speed, merging and overtaking are achieved easily.
When starting the Prius, the driver will notice a quieter start than in non-hybrid cars due to the electric generator being used to ignite the gas engine. When warmed up, the IC engine shuts off and the car is powered electrically until the gas engine kicks in around 15 mph. At low speeds, therefore, the Prius is primarily running on electricity yielding lower emissions and higher fuel efficiency.
Its compact lightweight battery pack is made of sealed nickel-metal hydride modules and produces 274 volts. The self-charging regenerative braking system, which converts brake energy to the battery pack, helps boost the driving range to over 600 miles per tank of gas in city driving, with an average fuel usage as high as 55 mpg.
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