- This engine is a strong hybrid type in the parallel class.Detailansicht Hybrid Motor image by 3rdTwin from Fotolia.com
All hybrid drivetrains do basically the same thing, but not all are created equal. There are two major types and two major classes of hybrid engines: "strong" vs. "weak" and "parallel" vs. "series," respectively. Each has its own strengths and weaknesses, functioning better under some circumstances than under others. Knowing what type of hybrid system your car has is essential to driving it efficiently while extracting maximum performance and longevity. - This is the type most often associated with the word "hybrid," but may not be the most common depending on the specific model year of the car. A strong hybrid system is capable of powering the vehicle on stored electric power alone through its entire speed range and holding it at cruise. Advantages: good fuel efficiency and good power when the gas and electric motor are used simultaneously. Disadvantages: very high production cost and requires large and heavy electric motor and battery pack. An example is the Toyota Prius.
- Hybrids do their best work when they're doing nothing at all. The reason the car has two different EPA mileage ratings (lower in the city and higher on the highway) is that it burns nearly as much gas sitting still as moving in traffic. A weak hybrid is a sort of combination motor/starter, and is only capable of starting the car from a standstill and powering it to about 20 mph. A weak hybrid system is optimized to eliminate the need to idle and ruin the engine while inching along in traffic. Advantages: high cost/benefit ratio, small battery pack and easily retrofitted to existing engine/transmission designs. Disadvantage: not quite as fuel efficient as a strong hybrid system. All Honda hybrids are the weak type.
- As of 2010, almost all hybrids on the automotive market are of the parallel class. In a parallel design, the car can run on gas power, electric power or both at the same time. Advantages: easily adaptable to existing chassis/powertrain designs, smooth transition from electric power to gas and fairly unobtrusive operation. Disadvantage: lower fuel economy than a series hybrid.
- Think of this type as an electric car with its own on-board generator to extend the range. The only common road vehicles currently utilizing a series approach are hydrogen fuel cell cars, in which the fuel cell itself acts as a sort of miniature power station. Other than that, you'll generally find parallel hybrid drivetrains in industrial applications like diesel/electric trains, construction equipment and ocean-going ships. As of 2010, General Motors, Ford, BMW, Lotus and Mercedes all have series hybrid systems in the works, but there's nothing on the mass market as of yet. Advantages: outstanding fuel efficiency, can use a very small displacement gas or diesel generator for easier packaging and lower production cost. Disadvantage: engine RPM isn't tied directly to wheel speed. This causes series hybrid vehicles to act less like cars and more like boats, where there is some lag between engine RPM rise and acceleration. There's nothing inherently wrong with this quirk; it's just foreign and irritating to most drivers.
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