[Paleopsych] Mechanical Engineering Magazine: The End of the M.E.?
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Mon Jun 6 18:00:38 UTC 2005
The End of the M.E.?
They call this "convergence." Old lines are changing, or disappearing
altogether. What it's doing under the hood is downright electrifying.
by Peter W. Huber and Mark P. Mills
The turf still divides up quite neatly. The electrical engineers move
the light stuff--electrons, power, bits, and logic. The mechanical
engineers do the heavy lifting; they move atoms. And, like it or not,
the MEs still control most of the real estate.
Look at our cars. They're made of big heavy things that shake, bounce,
and sway; they're propelled by pistons, shafts, gears, and belts;
controlled by shafts, gears, valves, and hydraulic fluids. All the
really important parts go click-click, bang-bang. The car is a 100 kW
(peak) machine. The stuff that hums instead of clanking, the electric
load, peaks at 2 kW.
Mechanical engineers control most of the rest of our energy economy,
too. The United States consumes 100 quadrillion Btus, or quads, of raw
thermal energy every year, in three broad sectors--electric power,
transportation, and heat--with consumption split (roughly) 40-30-30
among the three. But electric power plants themselves are mainly
thermomechanical: The furnaces, boilers, and turbines themselves
consume over half of the fuel; only about 16 quads worth of mechanical
energy actually get to the shafts that spin the generators that
dispatch the gigawatt-hours.
Komatsu's 930E is a 2,000 kW truck. A 16-cylinder diesel engine drives
a generator that powers electric motors on the wheels.
It doesn't have to be that way, and pretty soon it won't be. General
Electric's 4,400-horsepower, diesel-electric GEVO-12 locomotive is
powered by an enormous, diesel-fueled engine-driven generator;
everything beyond is electric. Komatsu's 930E--a monster mining truck
with 320-ton capacity--is propelled by a 2-megawatt Detroit
diesel-electric generator. Everything else, right down to the 12-foot
wheels, is driven electrically. Submarines have been largely
all-electric for decades, and the surface ships now on the Navy's
drawing boards are all-electric, from the propeller to the guns.
Thermomechanical engines are still the prime movers on all of these
platforms, but what they move is electricity. An on-board generator
powers an all-electric drivetrain; an electric motor drives the
propeller or wheels.
Electric drives are taking over because an electrical bus can convey
far more power in much smaller, lighter conduits, and do it far more
precisely and reliably, than even the best designed mechanical
drivetrain. Indeed, on the key metrics of speed and power density, the
electrical powertrain is about five orders of magnitude better.
Electricity moves at close to the speed of light; all thermal and
mechanical systems move at the speed of sound, or slower. It takes
10,000 driveshafts in 10,000 redlining Pontiacs to convey about as
much power (1 gigawatt) as a single power plant dispatches down a few
dozen high-voltage cables. By a very wide margin, electricity is
indeed the fastest and densest form of power that has been tamed for
But precisely because it is so fast and dense, electricity is
inherently difficult to control. Direct-drive electrical systems are
fast all right, but they tend to jitter, overshoot, jerk out of
control, and fall off the edge. The solution, historically, has been
to get mechanical again--wrap the electric coils and magnets around
heavy, inertial, and frictional components to get back to a simple and
steady source of mechanical power--rotating a shaft, say--which can
then be channeled through gears, belts, hydraulic fluids, and other
arrays of click-click, bang-bang logic well before it reaches the
final payload. Until recently, direct-drive electrical movers--systems
in which the power stays electric right down to the very threshold of
payload--have remained the exception, not the rule.
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
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.
Much the same transformation is well under way in the factory. The
19th-century factory was powered by a single driveshaft spanning the
length of the building; belts and chains delivered power to each
individual work bay. That primary mechanical driveshaft gave way to
electric power long ago, with motors powering the lathe, drill, or
milling machine in each workstation. But, by and large, the motors
still connect to shafts and belts and compressors. As in the car,
mechanical systems still control the last few meters of the
I, Sensitive Robot
The new industrial robots, however, are complex configurations of
electric servo motors; the electric power now runs right to the final
threshold of where the power is needed. Packed with sensors, the
robots are now precise, sensitive, and far more compact than any
mechanical alternative. They are also far more flexible--they now can
be instantly reconfigured to perform new tasks through software alone,
a dramatic advance over previous systems that required hours of manual
At the same time, high-power lasers--built around another family of
recently developed semiconductors--are rapidly taking over functions
previously viewed as mechanical. At kilowatt and megawatt power
levels, lasers don't move bits, they move material. They fuse powdered
metals into finished parts, without any machining, cutting, or
joining. They supply ultra-fine heating, soldering, drilling, cutting,
and materials processing, with fantastic improvements in speed,
precision, and efficiency. They create thermal pulses that can blast
metals and other materials off a source and deposit them on a target
to create entire new classes of material coatings. They move ink in
printers--not just desktop devices, but also the mammoth machines used
to produce newspapers. They solder optoelectronic chips without
destroying the silicon real estate around them, and they supply
unequaled precision in the bulk processing of workaday materials--heat
treating, welding, polymer bonding, sintering, soldering, epoxy
curing, and the hardening, abrading, and milling of surfaces.
Delphi has sold millions of its electric power steering units, which
eliminate hoses, pump, and hydraulic fluid.
Mechanical systems can be remarkably clever--just look at how a
high-end mechanical watch powers and times the movement of hands
around the watch face. In engines and machines of every description,
much of the mechanical engineering is still devoted to imposing a
desired logic on the flow of power. Until quite recently, EEs
themselves relied on at least semi-mechanical systems to choreograph
and order the flow of electricity. The huge electromechanical switches
that phone companies used to route calls until the 1960s set up
circuits by reconfiguring tapestry-like arrays of small,
electromechanical switches--thousands and thousands of them, clicking
away, day and night. But the advent of the transistor--invented by
Bell Labs--changed all that. Semiconductors now choreograph the flow
(or photonic) power through our watches and our phone lines.
Pushing semiconductors up the power curve took 20 years longer than it
did to push them down. But it has now been done. And these
fundamentally new technologies of "digital power" make possible an
extraordinary new variety of compact, affordable, product-assembling,
platform-moving, people- moving, and power-projecting systems that
seem to be all but magical. They will inevitably infiltrate, capture,
and transform the capital infrastructure of our entire energy
economy--the trillions of dollars of hardware that convert heat into
motion, motion into electricity, and ordinary electricity into highly
ordered electron and photon power.
One might say that the age of mechanical engineering was launched by
James Watt's steam engine in 1763, and propelled through its second
century by Nikolaus Otto's 1876 invention of the spark-ignited
petroleum engine. We are now at the dawn of the age of electrical
engineering, not because we recently learned how to generate
light-speed electrical power, but because we have now finally learned
how to control it.
Peter W. Huber, a former mechanical engineering instructor at MIT, is
a senior fellow of the Manhattan Institute. Mark P. Mills, a
physicist, is a founding partner of a venture fund, Digital Power
Capital. They are co-authors of The Bottomless Well (Basic Books,
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