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Roy
Quasi-Infallible Egocentric Tyrant
| Joined: | Mon Apr 4th, 2005 |
| Location: | Washington USA |
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Posted: Mon Jun 6th, 2005 05:02 pm |
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A continuation of the revolution to better, more efficient and more precise means of using power.
Roy
http://www.memagazine.org/contents/current/features/endofme/endofme.html
An excerpt:
Power in Control
But big motors and their electric power supplies can now be built compact and precise enough to mimic the small muscles of a hand. A key breakthrough occurred in 1982, when Hans Becke and Carl Wheatley (both at RCA) were granted a patent for what is now called the insulated gate bipolar transistor. IGBTs are high-power semiconductor gates. They control kilowatts almost as efficiently as logic semiconductors control the picowatts that we call bits.
Sensors have also become sufficiently small, fast, and accurate to provide real-time feedback of what's happening at the payload. And cheap microprocessors are now readily available to make sense of it all, and to constantly recalculate how much power to dispatch to the drive to make it do exactly what's needed.
Supplied with a suitably shaped and amplified stream of power, a loudspeaker vibrates a diaphragm through a Beethoven symphony; do the same with a hundred kilowatts, and you can run a Pontiac. What's new now is that inexpensive semiconductors are available to provide the extraordinarily precise control of very large amounts of electric power, at very low cost, in very compact controllers.
The sidestick, being tested by Mercedes-Benz, is part of a fully computer-controlled car handling system of the possibly near future.
Because they move less material in the middle, direct-drive powertrains have far less inertia and friction; and because they are informed by very fast sensors controlled by computers they can react much faster to the outside world. Direct-drive motors can thus reach levels of precision that are completely unattainable with any conventional technology. With less weight in the powertrain, and fewer moving parts, direct-drives are also more robust. Pneumatic and hydraulic fluids leak, turn into molasses when they get cold, and are easily contaminated. Shafts, belts, and pulleys need lubricants, and get bent out of shape when they expand or contract. They corrode and need periodic maintenance. Electric wires don't.
The transformation is already well under way in the car's peripheral systems. The belts and pulleys that drive water and oil pumps, and radiator cooling fans, are giving way to electric motors. The best brakes are already electrohydraulic; all-electric brakes will follow. With electronic throttles, the gas pedal sends electrical instructions to a microprocessor that controls the fuel injection system electronically. Drive-by-wire electric power steering began appearing in production vehicles in 2001. Passive, reactive, energy-dissipating springs and shock absorbers are being displaced by an active array of powerful linear motors that move wheels vertically as needed to maintain traction beneath and a smooth ride above.
And electric actuators will displace the steel camshaft on every valved engine. Put each valve under precise, direct, digital-electric control, actuated independently by its own compact electric motor—open and close each valve as dictated by current engine temperature, terrain, load, and countless other variables—and, in effect, you continuously retune the engine for peak performance. Belts, shafts, and chains melt away. Everything shrinks, everything gets lighter, and every aspect of performance improves—dramatically.
To meet this steadily rising demand for electric power, car manufacturers are making the transition to a 42-volt grid to replace the existing 14-volt grid. Lower-voltage wires just can't convey large amounts of power efficiently. A new 42-volt industry standard emerged recently, and half of global automobile production will be on a 42-volt platform within the next decade or so.
Next-generation integrated high-power alternator/starter motors have already been incorporated in BMWs and Benzes, and in Ford and GM trucks; about half of all new cars will have them by 2010. These units will supply the car with abundant, efficiently generated electric power, in a much lighter package, that will provide a virtually instant engine start as well.
Cheap in the Gearbox
This will set the stage for the last big step—the one already taken in monster trucks: Silicon and electric power will knock out the entire gearbox, driveshaft, differential, and related hardware; electric drives power the motors that turn the wheels. Power chips now make it possible to build high-power motors the size of a coffee can, and prices are dropping fast. When such motors finally begin driving the wheels, the entire output of the engine will have to be converted immediately into electricity before it is distributed, used, or stored throughout the car. It will take heavy-duty wiring and substantial
silicon drives and electric motors to propel a hybrid-electric sport utility vehicle down a highway at 70 mph—but they'll be far smaller than the steel structures in today's powertrain. Cars will shed many hundreds of pounds, and every key aspect of performance will improve considerably.
As this process unfolds, the engineering focus will shift inexorably toward finding the most efficient means of generating electricity on-board. Trains and monster trucks both use big diesel generators. Hybrid cars on the road today burn gasoline, but it's the fuel cell that attracts the most attention from visionaries and critics of the internal combustion engine. Remarkably elegant in its basic operation, the fuel cell transforms fuel into electricity in a single step, completely bypassing the furnace, turbine, and generator. In this scenario, mechanical engineering ultimately surrenders its last major under-the-hood citadel to chemical engineers...
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"The force and degree of a man's inner benevolence evokes in others a proportionate degree of ill-will" - Gurdjieff
"In a time of universal deceit, telling the truth is a revolutionary act." — George Orwell
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Johnny
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Posted: Fri Jun 10th, 2005 12:47 pm |
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I don't really see it as the end of mechanics, but a more substantive dialogue between mechanics and electronics.
The distinction between M.E. and E.E. is really an academic fabrication. Not that I think such distinction is a bad thing for education purposes, it's just what it is to me.
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