Automotive drive systems represent a major dilemma. A hybrid such as the Lexus GS 450h combines a 300-hp gasoline engine with a 50-hp electric motor. It also comes with a power indicator. During a recent road test, the engine generated only 35 hp to maintain a speed of 100 km/h. In everyday traffic, 50 ponies were enough to keep pace on boulevards and out toward the suburbs. Why 350 hp, then? To allow quick passing manoeuvres? To offer power levels worthy of a luxury car?
The conventional gasoline engine has a pretty big flaw -- its fuel consumption-to-horsepower ratio is not proportional. Fuel efficiency is indeed greater when the throttle is fully open and the engine speed remains somewhere between 50 and 66 percent of its capacity. Outside of these parameters, consumption increases significantly. Most of the time, a car engine operates outside of its maximum efficiency zone. An electric motor, on the other hand, will use 10 percent energy if it operates at 10 percent of its capacity.
Do you want an engine that’s powerful for safe passing manoeuvres but inefficient 95 percent of the time? That’s quite a dilemma!
Electric drive systems
Electric drive systems have been around for a really long time. In fact, the first invention by Ferdinand Porsche was an electric in-wheel motor… in 1897! At the dawn of the 20th century, electric motors were just as popular as steam or gasoline.
People loved them because they only required a switch being turned on in order to start, their available torque was significant (and eliminated the need for a clutch) and since power was directly proportional to the motor speed, there was no need for a complex, hard-to-use transmission either.
However, electric motors quickly lost popularity due to their limited range as well as the introduction of electric starters and synchronized transmissions on gasoline engines.
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| 2010 Lexus GS 450 h hybride |
The conventional gasoline engine has a pretty big flaw -- its fuel consumption-to-horsepower ratio is not proportional. Fuel efficiency is indeed greater when the throttle is fully open and the engine speed remains somewhere between 50 and 66 percent of its capacity. Outside of these parameters, consumption increases significantly. Most of the time, a car engine operates outside of its maximum efficiency zone. An electric motor, on the other hand, will use 10 percent energy if it operates at 10 percent of its capacity.
Do you want an engine that’s powerful for safe passing manoeuvres but inefficient 95 percent of the time? That’s quite a dilemma!
Electric drive systems
Electric drive systems have been around for a really long time. In fact, the first invention by Ferdinand Porsche was an electric in-wheel motor… in 1897! At the dawn of the 20th century, electric motors were just as popular as steam or gasoline.
People loved them because they only required a switch being turned on in order to start, their available torque was significant (and eliminated the need for a clutch) and since power was directly proportional to the motor speed, there was no need for a complex, hard-to-use transmission either.
However, electric motors quickly lost popularity due to their limited range as well as the introduction of electric starters and synchronized transmissions on gasoline engines.
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| 2010 Toyota Prius |