Gasoline-electric hybrid cars
ONE OF THE ANSWERS FROM MAJOR MANUFACTURERS TO POLLUTION: GASOLINE-ELECTRIC HYBRID CARS
* Autos híbridos a gasolina y electricidad
In the movies, we often see the cars of the future as a miniboxes moved by clean electricity. But for cars of normal size, performance and comfort the internal-combustion engine remains the best one. How about combining the two technologies?
The big problem with electric cars is not the electric motor, which can be produced of almost any power, but the batteries. To achieve sufficient electricity storage capacity they must be of considerable size and weight, so that they become very difficult to drag from one place to another. Then manufacturers are faced with the dilemma that in order to achieve high-performance, powerful electric motors should be installed, and consequently the range of the vehicle will be very short, or conversely, to get many hours of use the cars must have a very-low-power consumption, and that means small electric motors, with no more power to move anything else than a light but tight minibody.
A clear example of this is the fact that the first car to break the mark of 100 km/h (a feat achieved in Paris in 1899) was precisely an electric vehicle, the "Jamais Contente", built by Belgian Camille Jenatzy. But after covering like an arrow the required 1000 meters to set the record, it had to be towed by horses: its batteries were completely discharged.
Thus, other great engineers of the early automobile era who were also experimenting with electric cars, like the legendary Ferdinand Porsche, came to the same conclusion as Karl Benz: a vehicle will only be practical if it can carry onboard enough quantities of energy. The most practical and efficient way of storing energy remains, even a century later, the same as found by Benz in his research: by using a liquid fuel, preferably a petroleum product such as gasoline.
PETROLEUM: A HEADACHE
A century and millions and millions of cars later, petroleum no longer seems to be the best solution. One consequence that neither Benz nor Porsche had anticipated is that it is now believed that the burning of oil is killing the planet.
An analysis of the scientific reality of this is difficult, because the issue of global warming has been pitifully politicized. But let us suppose that the hypothesis in vogue ends up twisting wills.
Several studies show that probably we will still have oil until 2040, but by that time the melting of the North Pole would already be alarming. The first victim may be the polar bear, for being adapted to hunt only on ice. Climate problems would continue until reaching us. So most likely we will have to stop using oil before it runs out. Paradoxically, the real oil crisis is not its scarcity, but its abundance.
These studies still have many unknowns, specially because no one knows if the climate will stabilize if we stop burning oil. The current philosophy of the hypothesis in vogue says that it is best to be cautious and stop experimenting with our planet's atmosphere, because if we destroy it neither the Moon nor Mars may offer us an equivalent habitat. Anyway, things stand like they stand.
Electric motors seem to be the best option to keep the air clean. So we went back to thinking about cars like the "Jamais Contente". After more than a century, batteries have greatly improved, but they are still far from competing with liquid fuels as a way to store energy. An alternative would be fuel cells ran by clean hydrogen, which are the electric "batteries" used to generate power in the space shuttle. But while so far the technology has not come out from NASA towards our garages, many manufacturers are again looking to combine the best of both types of car: clean electric motors with conventional fuels of easy carrying.
THE HYBRID CAR
How can be clean a car that still has an exhaust pipe? The strategy in this particular case is not much to help the electric motor, but the electric motor helping the fuel engine overcome two major shortcomings of today's automobiles.
The first major shortcoming is that all that effort that the engine does to put the car into motion is lost at the next red traffic light. The brakes literally throw overboard all that kinetic energy or energy of the movement so difficultly developed. If there were a way to recover some of that energy it would be a breakthrough. And we see the light at the end of the tunnel if we remember what they told us in school: energy is neither created nor destroyed, but rather transformed. In practice it means that we can connect the wheels to some electric generators, so as to recharge some batteries. When the brakes are applied, the electric generators enter into action and steal energy from the wheels, whereby the vehicle speed decreases. This is similar to the electric brakes used for many years in heavy trucks and trains, with the difference now that the electricity is sent to batteries for storage. Then, when the light turns green and the driver accelerates, the recovered energy in the batteries go back to the wheels, by means of electric motors obviously. With all these steps the energy of motion is recycled and waste is reduced.
The second major shortcoming is that by varying the position of the accelerator pedal we greatly modify the filling of the cylinders of the internal-combustion engine. And not only that: the car's speed varies greatly, so the engine revs also vary, even with modern gearboxes. This is problematic because in order to have maximum fuel efficiency the engine must turn at an optimal rotational speed and with an optimum filling of the cylinders. Only in these conditions maximum energy will be extracted with minimum fuel consumption. Thus, the ideal is to maintain the engine always at one constant speed of rotation, and the throttle valve always in the same position, much as it were a train locomotive.
How to change the speed of a car without changing the rotation of its fuel engine? By installing an electric transmission. As follows: the energy from the fuel engine now will be used to keep a large battery constantly charged, and then from that battery, the stored energy will go to an electric motor to drive the wheels. Now the driver no longer controls with her or his foot the fuel engine, but simply the electric motor, which is the one that is going to move the car. In this way the fuel engine remains always at its optimum rev and throttle setting, generating all the energy very efficiently, and what varies the speed of the car is the electric motor.
Regarding massive availability, preliminary versions of this system existed for a long time on trains and big trucks, but apart from isolated efforts, only now they can be installed on normal cars, thanks to advances in computing. Computers decide when to run the fuel engine to recharge the batteries, and computers control the unique braking system to recover energy and send it back to the batteries. In addition, if the driver needs additional acceleration, computers are responsible for getting the gasoline-engine power directly to the wheels. This integrated system can maintain good comfort and performance, with good fuel economy and low pollution. Although it is not the permanent solution, the hybrid car is in the right direction.
IN THE REAL WORLD
Fuel consumption of a hybrid car is similar to a Diesel-engined car, only that, obviously, it is much less pollutant than a Diesel car. Hybrids typically consume less fuel in city driving than in highways, unlike a normal car.
If the driver needs little power most of the ride is done exclusively with the electric motor, and the gasoline engine works only sporadically to keep the batteries charged. If the driver requires additional power, for example on a slope or when overtaking another vehicle, the fuel engine enters into action immediately and transmits, via a mechanical differential gear, its full power to the wheels. Manufacturers continue using gasoline engines of traditional size, so this maximum acceleration remains the same, or even better, since there are now two engines.
The traditional, conventional brakes are not removed, for emergency stops. The power steering now works with electricity, and some trunk volume is lost because of the special battery. There is no need to plug the car to the wall at night.
The price of a hybrid car is higher than a normal car's, similar to the extra price you pay for a Diesel-engined car. But in many places there are tax incentives.
Manufacturers are offering after-sale guarantees similar to the guarantees of their normal cars, or even better yet.
The first modern hybrid car was the Toyota Prius, introduced to the market in 1997. This vehicle was exclusively designed for this alternative technology, with a highly aerodynamic bodywork and other details. Until 2003, more than 100 000 units were sold, and for 2004 an improved Prius appeared, similar in size to a Corolla. The new 2017 Prius has a 1,8-L gasoline engine of 71 kW (96 cv, 95 hp), together with an electric motor of 53 kW (72 cv, 71 hp). The combined maximum power is 90 kW (123 cv, 121 hp). This fourth-generation Prius, with basic equipment, sells for 2018 for a MSRP of US$ 23,575 in the U.S. market and comes with a warranty for the hybrid part of 8 years or 160 000 km.
Other manufacturers also presented their hybrids: Honda launched a special model called Insight in 1999. In 2003 it was decided to adapt the technology to a mainstream model, the Honda Civic. By 2005 the first hybrid SUV truck was introduced, a version of the Ford Escape. In 2006 Toyota finally adapted the technology to the best-selling car in the United States of America, the Camry. Out of the 4 389 851 Camrys that Americans bought up to 2017, an interesting figure of 382 276 have gasoline-electric hybrid engines. And this is only one of tens of hybrid models available for sale to the public today.
Over the last years Mazda, Mercury, Lexus, Lincoln, Cadillac, Chevrolet, GMC, Chrysler, Nissan, Saturn, BMW, Porsche, Volkswagen, Buick, Infiniti, Hyundai, Kia, Acura, Audi and Mercedez-Benz also released their versions, up to the point that today there are already circulating millions of units of hybrid cars worldwide.
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Originally published in ABC Color on 29 April 2007. Photograph: the Lohner-Porsche "Semper Vivus" prototype, ca. 1900, introduced the "Mixte" system, a gasoline-electric hybrid: behind the front seat are two internal-combustion engines, de Dion - Bouton single-cylinders of 2,6 kW (3,5 cv, 3,5 hp) each one, connected to two independent electric generators of 90 volts and 20 amperes (1,8 kVA) each under the seat and a battery of 44 lead-acid cells under the floor. These in turn feed the electric motors of 2 kW (2,7 cv, 2,7 hp) in the center of each front wheel. Visible, on the sides of the nose, are the radiators for cooling by liquid circulation, with a coolant storage tank under the rear seat. The fuel tank is the backrest of the same, while the vertical fat black cylinders next to the driver are the induction coils of the ignition system. There was no gearbox, or indeed any gear in the purely-electric transmission: the hand lever seen in the driver's side is the accelerator lever. The equipment includes four-wheel brakes: electric at the front and mechanical by band on external "crown" drum at the rear, plus parking brake. The metal tubular chassis (panels were wooden) has no suspensions system, although it is equipped with pneumatic tires and the battery case, with the seats on it, is mounted on springs. The electrical accumulators could move the automobile independently of the internal-combustion engines. With a mass of about 1200 kg, mainly due to the lead of the batteries of the day, the "Semper Vivus" however reached a speed of 35 km/h and the respectable range of 200 km. This remarkable vehicle was one of the first who took the name of Dr. Ferdinand, the legendary sports car Austrian engineer. Credit: Jacob Lohner & Co., Vienna. With permission from Dr. Ing. h. c. F. Porsche AG, Germany.