Hybrid vehicles: All you need to know
- by Abhishek Chaliha
- Mar 21, 2012
- Views : 15665
While the term 'hybrid vehicle' is very appealing to the eco mentalist and environment-conscious celebrity, not all of them understand how a hybrid vehicle functions to deliver the 'claimed' higher fuel efficiency as compared to conventional vehicles. Or do they?
The hunt for environmentally friendly vehicles has been on for quite a while now. Alternative sources of fuel (such as biodiesel and hydrogen) may reduce tailpipe emissions from internal combustion engines or not produce any at all, but these fuel types are not available in sufficient quantities.
Electric vehicles are not much good either in the real world, although there are no emissions from them, they have a limited drivable range and the batteries take way too long to recharge. They are also very expensive to buy.
To overcome the drawbacks of an electric vehicle, the hybrid vehicle was created. Besides reducing emissions, it offers increased mileage and decent driving range.
Hybrid vehicles feature a powertrain that includes a traditional internal combustion engine as well as an electric motor, batteries and a generator, which are the same components as in an electric vehicle.
Hybrid vehicles are of two types: parallel hybrids and series hybrids.
Here is how parallel hybrid vehicles work:
The internal combustion engine on parallel hybrid vehicles is mated to an automatic transmission that powers the wheels of the car. At this moment you may be wondering, if the car is powered by an internal combustion engine, what good is the lot of batteries, a generator and the electric motor in a hybrid vehicle?
The concept here is that while the internal combustion engine is there to offer adequate drive power. On the other hand, the electric motor powered by the battery helps drive the wheels of the car at low speeds. The electric motor is what comes into play when a hybrid vehicle is started. Also, when a hybrid vehicle is idling the electric motor is running and powering various electrical components, this means there are no tailpipe emissions at that moment from the vehicle.
Step on the accelerator pedal and the electric motor drives the vehicle forward. Usually, hybrid vehicles can go up to speeds of about 50km/h on battery power alone.
The benefits of this is that a vehicle uses more energy to start moving from standstill to low speeds than it uses to increase its travelling speed under normal driving conditions. This is why a conventional vehicle consumes more fuel in stop start traffic. As a result, hybrid vehicles consume no fuel in stop and go traffic when the battery is charged.
The downside of electric motors in hybrid vehicles is that they are not powerful enough to allow a car to achieve medium or high speeds. This means that a hybrid vehicle will not be able to keep up with traffic on the road. Of course, this problem can be tackled by fitting a bigger motor and more batteries. However, doing this will take up a lot of space in the vehicle, rendering it impractical for day to day use. Also, the added weight of heavy batteries will increase fuel consumption and tailpipe emissions.
Anyway, back to the accelerator pedal. When the driver wants to speed up the vehicle, due to limited capability of the electric motor, the internal combustion engine is powered up automatically and it starts driving the wheels of the car to achieve higher speeds and keep up with traffic on the road.
Hybrid vehicles seldom come with powerful internal combustion engines as that would increase tailpipe emissions, thereby rendering the concept of a hybrid vehicle pointless. This means hybrid vehicles are not very powerful, but to overcome this issue the electric motor on a hybrid vehicle works in tandem with the internal combustion engine to improve acceleration.
When the internal combustion engine is running, it also charges the battery on the car via the onboard generator that converts mechanical energy into electrical energy, allowing the battery to regain the lost charge during initial acceleration, high speed acceleration and idling. Under braking, hybrid vehicles use regenerative braking to convert kinetic energy from the brakes into electrical energy used to charge the onboard battery. The batteries on parallel hybrid vehicles do not need to be charged like that of electric vehicles as they are always charged by the internal combustion engine.
Moving on to series hybrid vehicles, here is how they work:
Like parallel hybrid vehicles, series hybrids use an internal combustion engine and an electric motor, a generator and batteries. However, the internal combustion engine in series hybrid vehicles never directly powers the wheels of the vehicle. Instead, it charges the battery of the vehicle via its generator. The electricity generated is then stored in the batteries, which in turn is used to power the wheels of the vehicle.
Series hybrid vehicles are also referred to as Range-Extended electric vehicles as the primary job of the internal combustion engine is to generate electricity that is used to drive the car.
Series hybrid technology is being taken up by an increasing number of car manufacturers as it is more efficient and simpler to parallel hybrid technology. Internal combustion engines on series hybrids are smaller and consume lesser fuel as they do not have to power the wheels of the vehicle. However, the electric motor, battery pack and generator in series hybrids are larger and more powerful than that of parallel hybrids. This adds to the cost and makes series hybrids more expensive than parallel hybrids.
Hybrid vehicles are the most successful type of eco-friendly vehicles in the market today due to their real world usability and practicality.
Having mentioned how hybrid vehicles work, it would be worth mentioning that when it comes to parallel hybrids (most hybrids on the road today are parallel hybrids), their efficiency is based on how the vehicle is driven. If a parallel hybrid vehicle is driven aggressively, then fuel consumption and tail pipe emissions will be higher than a conventional hatchback being driven in a normal manner.
Truth be told, hybrids are very appealing to environmental bodies and the eco-friendly mindset due to their theoretical low emission figures. However, in the real world it’s all about how you drive in case of parallel hybrids. Take it easy on the throttle and any regular vehicle’s fuel efficiency will rise, in turn, lowering harmful emissions.
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