Brief History of Hybrid Vehicle Development First built in the early 1900's by inventors tinkering with combinations of the electric motor and the gasoline engine, hybrid vehicles were dropped when gasoline-fueled vehicles became more reliable and easier to start, and gasoline fuel more readily available. Research and development of hybrid vehicles was revived by concern about oil dependency in the 1970's and about air pollution in the late 1980's. A number of hybrid vehicles have been built and tested since 1980. Some of these vehicles have impressed analysts with their performance and low levels of exhaust and petroleum consumption.

Interest in hybrid vehicles jumped in late 1993 with the announcement of funding for two major collaborations. The US Department of Energy signed a five-year, $138 million development agreement with General Motors and a $122 million agreement with Ford to design and build pre production hybrid prototypes that could be marketed in less than 10 years. [1] All these were done because hybrid electric vehicles are expected to be the future of vehicles worldwide. Definition One considers a vehicle to be a hybrid when it combines two or more sources of power. For example, a mo-ped (a motorized pedal bike) is a hybrid because it combines the power of a gasoline engine with the pedal power of its rider. Similarly, the gasoline-electric hybrid car is a combination of both an electric car and a gasoline-powered one.

That is, it makes use of both electricity and gasoline to provide the energy to turn the wheels of the car. Figure 1 shows a gas-powered car. [2] Components Of A Gasoline Powered Car The 4-cylinder engine converts gasoline into motion so that the car can move. The easiest way it does this is to burn the gasoline inside the engine. Therefore is acts as an internal combustion engine i.e. combustion takes place internally. Gasoline powered car engines typically have over 100 horsepower and operate at speeds up to 8000 RPM.

The fuel tank stores and supplies gasoline to the engine. It can typically store enough fuel to provide the engine with energy capable of moving the car through a distance of 300 miles or more. Figure 2 below shows an electric car, which has a set of batteries that provides electricity to an electric motor. The motor turns a transmission, and the transmission turns the wheels. [3] Components Of An Electric Car The batteries store and provide energy to the electric motor in an electric car just as the fuel tank does for the engine in a gasoline powered car. It usually gives the car a range of 50-100 miles which is much less than that typically provided by a fuel tank (300 miles).

The electric motor is the device that provides motion in an electric car. It converts the energy it receives from the batteries into motion which is used to turn a transmission which then in turn rotates the wheels. It is able to spin up to 15000 RPM and has up to 100 kW of power. Since this motion is connected to the transmission, the transmission also spins the wheel up to this rate.

Thus, electric cars would tend to move faster than gasoline powered cars. Components Common To Both The Electric Car And The Gasoline Powered Car The transmission is the device that does the actual turning of the wheel in both cars. There are several ways of combining the two sources of power found in a hybrid car. The Parallel Hybrid Car: This has a fuel tank which supplies gasoline to the engine. In addition, it has a set of batteries that supplies power to an electric motor. Both the engine and the engine motor can turn the transmission at the same time and the transmission then turns the wheels.

Figure 3 shows a typical parallel hybrid. The fuel tank and gas engine connect to the transmission. The batteries and electric motor also connect to the transmission independently. As a result, in a parallel hybrid, both the electric motor and the gas engine can provide propulsion power. The Series Hybrid Car: The gasoline engine in this car turns a generator and the generator can either charge the batteries or power an electric motor that drives the transmission.

Thus the gasoline engine never directly powers the vehicle. All of the components form a line that eventually connects with the transmission. [4] Hybrid Components Gasoline engine - The hybrid car has a gasoline engine much like the one you will find on most cars. However, the engine on a hybrid is smaller and uses advanced technologies to reduce emissions and increase efficiency. The engine turns the generator.

It is not able to power the car directly. Fuel tank - The fuel tank in a hybrid is the energy storage device for the gasoline engine. Gasoline has a much higher energy density than batteries do. For example, it takes about 1,000 pounds of batteries to store as much energy as 1 gallon (7 pounds) of gasoline.

Electric motor - The electric motor on a hybrid car is very sophisticated. Advanced electronics allow it to act as a motor as well as a generator. For example, when it needs to, it can draw energy from the batteries to accelerate the car. But acting as a generator, it can slow the car down and return energy to the batteries.

Generator - The generator is similar to an electric motor, but it acts only to produce electrical power. It is used mostly on series hybrids. It is where the gas engine's power gets converted to electrical power to drive the motor or charge the batteries. Batteries - The batteries in a hybrid car are the energy storage device for the electric motor. Unlike the gasoline in the fuel tank, which can only power the gasoline engine, the electric motor on a hybrid car can put energy into the batteries as well as draw energy from them. They can store energy recovered from braking or generated by the motor.

Transmission - The transmission on a hybrid car performs the same basic function as the transmission on a conventional car i.e. turns the wheels. The motor can spin fast enough so that the transmission needs only one gear. Some hybrids, like the Honda Insight, have conventional transmissions. Others, like the Toyota Prius, have radically different ones like the CVT.

CVT stands for Continuously Variable Transmission. It is used to vary the transmission ratio in vehicles continuously. The way CVT works depends on the type: Friction CVTs vary the radius of the contact point between two rotating objects, thus the tangential velocity; Hydrostatic CVTs vary the fluid flow with variable displacement pumps into hydrostatic motors; Ratcheting CVTs vary the stroke of a reciprocating motion, which is connected to a free-wheel, resulting unidirectional rotation. Image courtesy DaimlerChrysler The Mercedes-Benz M-Class HYPER -- a hybrid concept vehicle [5] Reasons For The Introduction Of Hybrid Electric Vehicles To reduce tailpipe emissions: Gasoline cars are a major source of these emissions. Many attempts are being made by several organizations to reduce the greenhouse gas emissions from cars through the development of hybrid electric vehicles.

For example, Nutley, NJ-based Hoffman-La Roche, Inc. (Roche), the U.S. prescription drug unit of the Roche Group, recently announced plans to integrate Toyota Prius and Ford Escape hybrid electric vehicles into its pharmaceutical sales fleet in an effort to help achieve the company's goal of reducing greenhouse gas emissions by 10 percent over the next five years. [6] To improve mileage: Automakers in the US need to meet Corporate Average Fuel Economy (CAF'E) standards as required by law. At present, all new cars sold should be 27.5 mpg (8.55 liters per 100 km). [7] To overcome the shortcomings of an electric car: Electric cars have a short charge. They lacked the range (energy density of electric-vehicle batteries hovered around 70 to 100 watt-hours per kilogram, which automotive engineers called unacceptable) and the quick recharge time the auto industry said it needed.

An example is seen in the case where GM introduced the EV 1 in 1996. It had a top speed of 183 MPH, faster than any other production car out. It had a limiter that would not let it get above 85 MPH, because to drive the car at 183 MPH would deplete the batteries of their charge within 10 minutes. [8] Energy Consumption: Hybrid Electric Vehicles consume less energy than Internal-Combustion Engine (ICE) vehicles.

[9] Why Are Hybrid Electric Vehicles A Better Choice? An important aspect of hybrid electric vehicles is that they make use of smaller engines. There are many advantages to this: Big engines are heavier than smaller ones so the car uses more energy anytime it accelerates or drives up a hill. The displacement of the cylinders is larger so each cylinder requires a greater volume of fuel. Bigger engines usually have more cylinders, and each cylinder uses fuel every time the engine fires, even if the car isn't moving. These are the reasons there is a difference in the mileage of two cars of the same model with different engines.

If both cars are driving along the freeway at the same speed, the one with the smaller engine uses less energy. Both engines have to output the same amount of power to drive the car, but the small engine uses less power to drive itself. In a hybrid car, the gasoline engine can be much smaller than the one in a conventional car and thus can be more efficient. The engine in the hybrid car is powerful enough to move the car along on the freeway, but when it needs to get the car moving in a hurry, or go up a steep hill, it needs help. That 'help' comes from the electric motor and battery -- this system steps in to provide the necessary extra power. The gas engine on a conventional car is sized for the peak power requirement (those few times when you floor the accelerator pedal).

In fact, most drivers use the peak power of their engines less than one percent of the time. The hybrid car uses a much smaller engine, one that is sized closer to the average power requirement than to the peak power. Ways Hybrid Electric Vehicles Reduce Energy Consumption Besides a smaller, more efficient engine, today's hybrids use many other tricks to increase fuel efficiency. Some of those tricks will help any type of car get better mileage, and some only apply to a hybrid. To squeeze every last mile out of a gallon of gasoline, a hybrid car can: Recover energy and store it in the battery - Whenever you step on the brake pedal in your car, you are removing energy from the car. The faster a car is going, the more kinetic energy it has.

The brakes of a car remove this energy and dissipate it in the form of heat. A hybrid car can capture some of this energy and store it in the battery to use later. It does this by using 'regenerative braking. ' That is, instead of just using the brakes to stop the car, the electric motor that drives the hybrid can also slow the car. In this mode, the electric motor acts as a generator and charges the batteries while the car is slowing down.

Sometimes shut off the engine - A hybrid car does not need to rely on the gasoline engine all of the time because it has an alternate power source -- the electric motor and batteries. So the hybrid car can sometimes turn off the gasoline engine, for example when the vehicle is stopped at a red light. Figure 5. The frontal area profile of a small and large car Use advanced aerodynamics to reduce drag - When you are driving on the freeway, most of the work your engine does goes into pushing the car through the air.

This force is known as aerodynamic drag. This drag force can be reduced in a variety of ways. One sure way is to reduce the frontal area of the car (Figure 5). Think of how a big SUV has to push a much greater area through the air than a tiny sports car. Reducing disturbances around objects that stick out from the car or eliminating them altogether can also help to improve the aerodynamics.

For example, covers over the wheel housings smooth the airflow and reduce drag. And sometimes, mirrors are replaced with small cameras. Use low-rolling resistance tires - The tires on most cars are optimized to give a smooth ride, minimize noise, and provide good traction in a variety of weather conditions. But they are rarely optimized for efficiency. In fact, the tires cause a surprising amount of drag while you are driving. Hybrid cars use special tires that are both stiffer and inflated to a higher pressure than conventional tires.

The result is that they cause about half the drag of regular tires. Use lightweight materials - Reducing the overall weight of a car is one easy way to increase the mileage. A lighter vehicle uses less energy each time you accelerate or drive up a hill. Composite materials like carbon fiber or lightweight metals like aluminum and magnesium can be used to reduce weight. [10] Despite the advantages of hybrid vehicles, they are a middling choice whose future is far from assured. They are likely to be a victim of regulatory circumstance in the near term, pushed aside by improvements in gasoline emissions and by the Zero Emission Vehicles (ZEV) mandate which states that a specified percentage of manufacturers's ales consist of Hevs.

[11] In the longer term, they will be squeezed between improving batteries and emerging fuel cells. If only fuel cells and advanced batteries falter, hybrid vehicles would have considerable promise and could play a central role in creating a more sustainable transportation system. Nissan Motor Company CEO Carlos Ghosn announced that he is unsure whether hybrid electric vehicles (HEVs) will remain competitive in the compact car market if the price of gasoline drops in the future. Speaking at a news conference in Tokyo, Ghosn acknowledged that Nissan will unveil a new HEV in 2006 'as planned,' but only to meet tightening emission regulations in California. Ghosn expressed doubt that U.S. benchmark crude prices would remain at current levels of $50 per barrel, which is fueling strong demand for HEVs. Reuters said Nissan instead plans to market its new fuel-efficient, gasoline-powered T iida compact car to environmentally conscious drivers.

[12] Disadvantages Of Hybrid Electric Vehicles By combining two propulsion systems and their associated energy storage units, they are inherently more complex than both pure battery-powered electric and pure internal-combustion vehicles.

Bibliography

How I found my references... Send me your comments... Homepage... Comments 1] Daniel Sperling; Future Drive: Electric Vehicles and Sustainable Transportation, pg 101 [2] web web web web I TOF 0 A 122672547&don = 5! x rn 15 0 A 122672547? sw a ep ='s war 94187, Electric and Hybrid Vehicles Today, Sept 30, 2004 p 0, Article A 122672547 [7] web web corner 1.
html [9] Daniel Sperling; Future Drive: Electric Vehicles and Sustainable Transportation, pg 100 [10] web Daniel Sperling; Future Drive: Electric Vehicles and Sustainable Transportation, pg 2 [12] Electric and Hybrid Vehicles Today, Oct. 7, 2004, p 0;