TECHNOLOGY EDUCATION
Mr. Sabur – Tech Systems
Mr. Smith – Tech Foundations
NEW YORK TIMES
Smarter Valves, Batteries and Brakes Cut Gas Guzzling a Sip at a Time
SOME advances in fuel economy are big and some are little. Here are three smaller innovations that are in production or will soon be, and that might cut gas consumption by 10 percent or more.
Cylinder Cutoff
An engine with eight cylinders has plenty of power for a highway entrance ramp, but a V-8 engine may not need to be running on all cylinders to cruise the highway just fine and more cheaply.
So could it be a V-4 some of the time? Deactivating some of the cylinders to save fuel seems simple, but it has been hard to achieve. Engineers tried several times with disappointing results, most recently in 1981 when General Motors introduced an 8-6-4 engine that shut down either two or four cylinders at a time to economize. Drivers did not like the engines, and the company shelved them after just one year.
Now the innovation is back in some top-quality vehicles. Estimates for fuel savings range from as low as 6 percent to as high as 12 percent for highway cruising.
What makes it work today is the huge electronic sensing and computing power in cars, coupled with precisely controlled fuel injection systems. The secret lies in closing the intake and exhaust valves of each cylinder at the right instant, and keeping the valves sealed so that the cylinders don't pump air and fuel. Fuel injection and electric spark are also cut off.
The engine runs normally in every other way, and lubrication continues to get to the inactive cylinders. Other technology, including noise-canceling hardware and vibration-deadening engine mounts, keeps the partly deactivated engine humming.
Honda is introducing a V-6 engine that uses only three cylinders when the car is cruising or coasting. Its "variable cylinder management" overhead cam engine is used in the Accord's gas-electric hybrid sedan and will also be available on the Odyssey minivan.
G.M., which calls its system "displacement on demand," uses hardware by Delphi Automotive Systems and the Eaton Corporation. In some V-8 engines in trucks and S.U.V.'s, four of the eight cylinders turn off under light loading. The engines are pushrod-operated, an older technology.
"The engine is operating as it normally would, you just don't have force being applied to all of those cylinders," said Edward J. Martin, Delphi's product line manager. He described potential savings as "one month of free gas."
DaimlerChrysler has adopted a similar system termed "multidisplacement," for an optional version of its V-8 Hemi engine in the Chrysler 300 sedan, Dodge Magnum RT and Jeep Grand Cherokee.
Golf-Cart Start
Rapid start-stop technology, like a golf cart's engine stopping when the brake is applied and starting up again when the accelerator pedal is pushed, is another fuel saver. By eliminating idling at stoplights and in traffic jams, start-stop systems are expected to save about 15 percent in fuel. The biggest benefit, though, may be in lowered emissions; engines are at their worst when idling.
Car and truck engines are much harder to crank up than a golf cart's engine is. Even so, new computers and sensors make it possible to start and stop instantly at a traffic light.
Start-stop systems use a powerful electric motor to instantly spin the engine to idling speed, without the gear-grinding whine of a normal starter motor. Drivers don't perceive a time lag when they step on the gas.
The technology is not limited to traffic stops. Some vehicles use engine cutoff when they are coasting or decelerating.
Two kinds of start-stop systems are in production, with the most common being in hybrid vehicles. Those systems are usually high-voltage, with an expensive electric motor mounted directly in the drivetrain.
A less-expensive system that may be seen on many more vehicles in the future uses a stronger version of the ordinary alternator and its belt drive. Ordinarily, the alternator just makes electricity and charges the battery. Start-stop alternators turn that system around. They are engineered to be motors as well as generators, and with a brawnier belt drive they can become high-efficiency starters. The 2006 Saturn VUE is expected to carry G.M.'s Belt Alternator Starter system; other manufacturers have been introducing such belt-driven systems, too, and automotive suppliers expect the systems to begin rolling out in large numbers in the 2008-2009 time frame.
Smarter Batteries
Honda's new Accord hybrid depends on a big battery, but that battery is already lighter than the one powering the earlier Civic hybrid.
"They're very similar, but the Accord one is more compact and with a different shape," said Chuck Schifsky, a Honda spokesman. "A lot of that is just because we've learned more, and the battery manufacturers and battery engineers have learned more."
Hybrids are using nickel-metal hydride batteries to store and return high-voltage energy to the vehicle. The battery packs typically weigh hundreds of pounds, ride far from the engine compartment and come with their own computer controls and cooling system.
The computer is like a coach who is making instant decisions about a game in progress: it decides which cells to charge and discharge, how fast the charge should be and what temperature the battery needs for best operation.
But the exotic batteries are expensive, and the auto industry is far from done with traditional batteries that have powered electrical systems for a century. New ways to monitor and run those batteries let the car make intelligent decisions.
Johnson Controls makes a monitoring system named PowerWatch, which keeps an eye on the ordinary battery and knows how healthy it is and what tasks it can do. On the hybrid side, it can avoid shutting down the engine if the system determines there is not enough power to restart it.
A system like PowerWatch can also save fuel. The alternator steals some engine power to generate electricity, and it constantly produces the same amount of electric voltage whether the car needs it or not. A monitoring system can dial back the voltage the alternator creates when it is not needed, creating a lighter load on the engine and saving fuel.
In addition, such invisible monitoring systems can predict exactly when the battery will wear out. Coupled with wireless communications, it's possible your car may give you a call some cold night to say, "I won't be able to start in the morning; don't worry, I've already called the tow truck."