Hybrid vehicle engines and how they work from Wikipedia.org
Hybrid vehicle engines and how they work
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[edit] Gasoline assist
The first type can propel itself using only the electric motor at very low speeds. The electric motor also has the ability to kick in and help out the gasoline engine when more power is needed, such as when passing or climbing a steep grade. The Toyota Prius and the Ford Escape Hybrid fall into this category.
When a car like the Toyota Prius accelerates from a standstill, the electric motor gets the vehicle rolling and continues to drive it up to around 25 mph before the gasoline engine automatically starts up. Under hard acceleration from a stop, the gas engine starts immediately to provide maximum power. The electric motor and the gas engine also work in tandem when driving conditions demand more power, such as while climbing a hill or passing other vehicles. Because the electric motor is used so much at low speeds, the Prius and Escape get better mileage in the city than they do on the highway.
[edit] Electric assist
The second type uses the electric motor only to assist the gasoline engine when it needs extra boost, again during brisk acceleration or when going up a hill. The Civic Hybrid and Honda Insight fall into the second category.
When a car like the Honda Insight and Civic Hybrid, the electric motor assists the gas engine only when driving conditions demand more power, such as during hard acceleration from a stop, while climbing a hill or passing other vehicles. As with normal, gas-powered cars, these hybrids get better fuel economy while cruising on the highway, as that is when the gas engine is least taxed.
[edit] Environmental issues
[edit] Fuel consumption and emissions reductions
The hybrid vehicle typically achieves greater fuel economy and lower emissions than conventional internal combustion engine vehicles (ICEVs), resulting in fewer emissions being generated. These savings are primarily achieved by four elements of a typical hybrid design:
- recapturing energy normally wasted during braking etc. (regenerative braking) This is a mechanism that reduces vehicle speed by converting some of its kinetic energy into another useful form of energy, especially in stop-and-go traffic.
- having significant battery storage capacity to store and reuse recaptured energy;
- shutting down the gasoline or diesel engine during traffic stops or while coasting or other idle periods;
- improving aerodynamics ; (part of the reason that SUVs get such bad gas mileage is the drag on the car. A box shaped car or truck has to exert more force to move through the air causing more stress on the engine making it work harder. Improving the shape and aerodynamics of a car is a good way to help better the gas mileage and also improve handling at the same time.
- using low rolling resistance tires ; (tires these days are made to give a quiet , smooth ride but rarely is efficiency considered. These tires cause a great deal of drag, once again making the engine work harder , consuming more gas mileage. Hybrid cars use special tires that are more inflated than regular tires and stiffer, which reduces the drag by about half, improving fuel economy by relieving stress of the engine.
- relying on both the gasoline (or diesel engine) and the electric motors for peak power needs resulting in a smaller gasoline or diesel engine sized more for average usage rather than peak power usage.
These features make a hybrid vehicle particularly efficient for city traffic where there are frequent stops, coasting and idling periods. In addition noise emissions are reduced, particularly at idling and low operating speeds,[22] in comparison to conventional gasoline or diesel powered engine vehicles. For continuous high speed highway use these features are much less useful in reducing emissions.
