Making and Breaking Codes
Taming the Automobile
America’s love affair with the automobile is legendary. On the strengths of this well entrenched bond, the auto industry has flourished and competition has driven them to push the envelope of technological innovation in automotive design and manufacturing to its limits. The number of automobiles on the streets of the US is estimated at about 150 million and the population of the US is 270 million. The country with the second largest number of automobiles is Japan with 47 million, belonging to a population of 126 million.
Cars are very useful. They provide transportation on demand. They provide independence, security, convenience, efficiency, enhanced productivity and makes getting around from here to there and back quick and easy. They also consume gasoline, produce harmful exhaust, cause congestion, fill up parking space and encourage waste. Is there a middle where we can meet, such that the passion and the convenience of the automobile can coexist with the needs for energy preservation and environmental concerns? Today, technology seems to be hovering on a possible answer—the hybrid car.
The attraction for automobiles, specially in the US, is not just passion, it is rooted in necessity and the individualistic character. Much of US has traditionally been largely rural and agricultural in nature. The land is fertile and vast, and the population in rural areas is low in density. To cultivate the huge tracts of American farms, people depended (and still do) upon technology, in the form of moving equipment.. The workhorses on the farms are trucks, cars, tractors, grain elevators and all kinds of seemingly crude mechanical contraptions. These things allows a farmer (and his few offspring) to run a huge operation of sowing, growing, harvesting; raising livestock, and delivering the finished food products to the far away markets, with little or no non-family human help. Due to farming roots, a large number of Americans are traditionally and intimately tuned to mechanical things, and very comfortable with automobiles.
Even cities in the US are semi-rural. Of the approximately 250 cities (or towns) in the USA, about 4 or 5 can be considered dense and urban. The rest are smaller towns and or metropolises with sprawling suburbia. Houses are spread far apart form each other and the closest store is at least a mile away, (actually 3-4 miles is more appropriate). The density of the population is low enough that public transportation cannot be made efficient. Just for example, 3 million people, covering over 1000 square miles of space, inhabit the Phoenix metropolitan area, where I live. The low population densities, even in urban areas, cause the dependence on personal transport. Of course, there is considerable debate over how this happened—city planners blame the availability of cheap cars to the result of huge sparsely populated suburbs.
Thus the car is completely embedded in the life of every American. We get up early in the morning; fill a large mug with strong black coffee, and rush to get into the car. Then it’s a good 30 minutes of leisurely drive, sometimes fighting traffic, while listening to some incessant banter on the radio to get to the workplace. A few hours later, the tummy calls for refueling and we drive over somewhere for lunch. At the end of the day, its time to get home, and of course, that means a stop at some stores to get supplies, food, the ever-important cold beer, and maybe some other errands. Eventually, after the evening settles, single people go out to meet other people—friends, dates, family. Families go out for dinner or movies or shopping. Children are shuttled to and from school, and then to attend extra curricular activities, music lessons, sports practices and such. On weekends there are outings, camping trips, long drives and the incessant need for shopping. It’s a dizzy whirl of activity, all made possible by the car.
The automobile industry of course rises to its responsibility of meeting and exceeding the need for automobiles, by providing a dazzling array of choices. There are approximately 30 brands (or “makes”) of cars on the market in the US; made in the US, Japan, Germany, Mexico, Korea, Sweden, United Kingdom and Italy. These makes put out of about 200 “models” of cars. Each make and model is revised every year—sometimes major, often minor design changes are done on a yearly basis. Hence, the make and model and year, of a car that a person drives is considered—rightly so—and expression of that person’s individuality.
People buy cars for transportation, and image. The price range of new cars range from a little lower than $10,000 to higher than $100,000. The majority of the cars fall in the $17,000 to $22,000 range. Hence there are lots of cars to choose from in the $20,000 price point, how does one decide? Some people go for looks, some go for reliability, some go for power, others go for size (big, or small). Personal preferences are the mainstay of car selection and hence the car a person owns shows his or her priorities. Of course, the used car market is amazingly huge, and prices are all over the map (the majority being in the $2,000-$10,000 range).
Technology of course has played a massive role in the car industry. The only thing that seems to have remained relatively constant is that a car has 4 wheels and a piston driven internal combustion engine. Other variants such as 3 wheeled cars, and rotary engines have been tried, and have failed.
In the 1980s the popular cars were the sedans (4 doors) and the sporty cars (2-doors, low profile, sleek looking). The focus of innovation in car design was to (i) increase reliability (ii) make cars more ergonomic and (iii) increase fuel efficiency and (iv) decrease production costs. All carmakers succeeded on most of the above goals. Better manufacturing processes, higher quality materials and innovative usage of robots contributed to significant increases in reliability and decreased manufacturing costs. More advanced alloys used in engines and a host of mechanical fine tuning (better valve designs, variable valve timings, computerized fuel systems) led to more efficient engines. A lot of thought went into the design of the “cockpit”—arranging knobs, dials and controls in better positions, making the interior look more spacious without making the car bigger, adding touches such as drink holders, coin compartments and myriads of gadgets made driver comfort higher. Suspension system innovations made the ride more comfortable and the handling more precise. Even air-conditioning, which was an expensive option in the early 1980’s, became standard equipment on all cars by the end of the decade. The efficiency of these cars, for average driving conditions, ranged from 30 miles per gallon (12.7 km/L) for small cars to 25 miles per gallon (10.5 km/L) for larger cars.
The 1990’s saw the buyers shift from sedans and sporty cars to the large covered truck like vehicles (called SUV’s or Sport Utility Vehicles) and the minivans (a 7 passenger van). So once again the industry responded with better designs for these beasts. Today’s SUV’s and minivans drive like cars even thought the are bigger and higher and bulkier. How a monster can handle and turn like a compact is quite an amazing mechanical innovation. Due to the size and weight of these vehicles, and the need for larger engines (6 cylinders) the efficiency drops to about 18 miles per gallon (7.6 km/L).
Finally, in 2000 the saw the commercialization of the hybrid car. Hybrid technology is still in its infancy, and the future is unclear. But three things have been demonstrated—hybrid cars are ready for mass production, prices are high but not outrageous, and the efficiency is terrific and the emissions are low. The first two mass produced cars, on sale right now, is the 2-door, 2-seater, Honda Insight ($18,000) and the 4-door, 5-seater Toyota Prius ($20,000).
To understand the hybrid car, we need to see why conventional gasoline powered cars are really quite inefficient. Even though the current engine designs are the result of over 20 years of research into high efficiency engines, the gasoline engine has two problems. When a car is idling or driving at low speeds, the engine turns slowly and inefficiently. When the car is driving at a high, constant speed, the engine is delivering a fraction of its rated power, and this is not efficient either. Coupled with the inefficiency comes the emission problem—the more efficiently the engine runs, the cleaner is the exhaust, and vice versa. Hybrid technology allows a car to be equipped with a small engine that always runs at peak efficiency and hence maximize mileage and minimize emissions.
There are two possible kinds of hybrids. In the “series hybrid” a gasoline motor drives a generator at a constant speed. The generator charges batteries and the batteries feed a electric motor that runs the car. The advantage is that the gasoline engine runs at high speed and peak efficiency. The fluctuating demands of power are provided by the electric motor, running off of the batteries. The batteries get charges when the car is not accelerating, and gets discharged when there is demand for a lot of power. The disadvantage is that power is converted from mechanical to electrical and back to mechanical. Conversion causes loss.
Even more efficient (and complicated) than the series hybrid is the “parallel hybrid”. In this design, not all power has to go from engine to electricity to motor, reducing conversion loss. As in the series hybrid, the small gasoline engine runs at full efficiency and (almost) constant speed. Power from the engine is used to drive the car, but if the car cannot use all the energy the engine provides, which is often the case, and then the residual energy is converted to electricity and used to charge batteries. However, under acceleration, the engine is actually too weak to provide a good pick-up and then a electric motor kicks in and boosts the engine power to provide good oomph (using power from the batteries). When the car is slowing down, the electric motor acts in reverse and generates electricity and charges batteries, thus recovering energy that would be lost due to braking (this is called regenerative braking).
While the Toyota and the Honda use quite different strategies to implement the parallel hybrid concept, the result is quite remarkable. The Honda is a small car with a 1-liter engine, and gets 63 miles to the gallon (26 km/L) and the Toyota is larger, with a 1.5-liter engine, and gets 48 miles per gallon (20 km/L). Both produce very little emissions and can be termed super-clean. Note that a conventional 1.5-liter engine put into the Toyota, is expected to provide about 30 miles per gallon, and produce much higher levels of nasty emissions. And unlike electric cars (another failure) they do not need to be recharged frequently, and yes, they have air-conditioning. Finally, a great advantage is that hybrid cars do not loose efficiency in stop-and-go driving in congested city traffic (a severe problem with conventional gasoline engines).
Of course, now is just the beginning. Coupled with alternative energy sources, different engine designs, more innovative coupling of electric power, gasoline and maybe fuel cells, the future of hybrid technology can hold many surprises. All we can say now, is that we have seen lights of the dawn of energy efficient, clean personal transportation.
Partha Dasgupta is on the faculty of the Computer Science and Engineering Department at Arizona State University in Tempe. His specializations are in the areas of Operating Systems, Cryptography and Networking.