Automobile
Automobile Systems
Automobiles are powered and controlled
by a complicated interrelationship between several systems. This diagram shows
the parts of a car with a gas engine and manual transmission (the air filter
and carburetor have been removed to show the parts beneath but usually appear
in the space above the intake manifold). The major systems of the automobile
are the power plant, the power train, the running gear, and the control system.
Each of these major categories include a number of subsystems, as shown here.
The power plant includes the engine, fuel, electrical, exhaust, lubrication,
and coolant systems. The power train includes the transmission and drive
systems, including the clutch, differential, and drive shaft. Suspension,
stabilizers, wheels, and tires are all part of the running gear, or support
system. Steering and brake systems are the major components of the control
system, by which the driver directs the car.
Automobile, self-propelled vehicle
used primarily on public roads but adaptable to other surfaces. Automobiles
changed the world during the 20th century, particularly in the United States
and other industrialized nations. From the growth of suburbs to the development
of elaborate road and highway systems, the so-called horseless carriage has
forever altered the modern landscape. The manufacture, sale, and servicing of
automobiles have become key elements of industrial economies. But along with
greater mobility and job creation, the automobile has brought noise and air
pollution, and automobile accidents rank among the leading causes of death and
injury throughout the world. But for better or worse, the 1900s can be called
the Age of the Automobile, and cars will no doubt continue to shape our culture
and economy well into the 21st century.
Automobiles are classified by
size, style, number of doors, and intended use. The typical automobile, also
called a car, auto, motorcar, and passenger car, has four wheels and can carry
up to six people, including a driver. Larger vehicles designed to carry more
passengers are called vans, minivans, omnibuses, or buses. Those used to carry
cargo are called pickups or trucks, depending on their size and design.
Minivans are van-style vehicles built on a passenger car frame that can usually
carry up to eight passengers. Sport-utility vehicles, also known as SUVs, are
more rugged than passenger cars and are designed for driving in mud or snow.
Auto manufacturing plants in 40
countries produced a total of 63.9 million vehicles, including 42.8 million
passenger cars, in 2004, according to Ward’s Auto, an auto industry analyst.
About 16.2 million vehicles, including 6.3 million passenger cars, were
produced in North America in 2004. For information on the business of making
cars, see Automobile Industry.
The automobile is built
around an engine. Various systems supply the engine with fuel, cool it during
operation, lubricate its moving parts, and remove exhaust gases it creates. The
engine produces mechanical power that is transmitted to the automobile’s wheels
through a drivetrain, which includes a transmission, one or more driveshafts, a
differential gear, and axles. Suspension systems, which include springs and
shock absorbers, cushion the ride and help protect the vehicle from being
damaged by bumps, heavy loads, and other stresses. Wheels and tires support the
vehicle on the roadway and, when rotated by powered axles, propel the vehicle
forward or backward. Steering and braking systems provide control over
direction and speed. An electrical system starts and operates the engine, monitors
and controls many aspects of the vehicle’s operation, and powers such
components as headlights and radios. Safety features such as bumpers, air bags,
and seat belts help protect occupants in an accident.
II
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POWER SYSTEM
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Internal-Combustion Engine
The four-stroke internal-combustion
engine is used in vehicles powered by gasoline or diesel fuel. This series of
slides and animations shows the parts of the engine that make the four-stroke
cycle work.
Gasoline internal-combustion engines
power most automobiles, but some engines use diesel fuel, electricity, natural
gas, solar energy, or fuels derived from methanol (wood alcohol) and ethanol
(grain alcohol).
Most gasoline engines work in
the following way: Turning the ignition key operates a switch that sends electricity
from a battery to a starter motor. The starter motor turns a disk known as a
flywheel, which in turn causes the engine’s crankshaft to revolve. The rotating
crankshaft causes pistons, which are solid cylinders that fit snugly inside the
engine’s hollow cylinders, to move up and down. Fuel-injection systems or, in
older cars, a carburetor deliver fuel vapor from the gas tank to the engine
cylinders.
The pistons compress the
vapor inside the cylinders. An electric current flows through a spark plug to
ignite the vapor. The fuel mixture explodes, or combusts, creating hot
expanding gases that push the pistons down the cylinders and cause the
crankshaft to rotate. The crankshaft is now rotating via the up-and-down motion
of the pistons, permitting the starter motor to disengage from the flywheel.
A
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Engine
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Automobile Engine
The engine is the most important part of
an automobile. The rest of the automobile is built around the engine, with
systems that help the engine run and transfer power to the wheels.
The basic components of an
internal-combustion engine are the engine block, cylinder head, cylinders, pistons,
valves, crankshaft, and camshaft. The lower part of the engine, called the
engine block, houses the cylinders, pistons, and crankshaft. The components of
other engine systems bolt or attach to the engine block. The block is
manufactured with internal passageways for lubricants and coolant. Engine
blocks are made of cast iron or aluminum alloy and formed with a set of round
cylinders.
The upper part of the
engine is the cylinder head. Bolted to the top of the block, it seals the tops
of the cylinders. Pistons compress air and fuel against the cylinder head prior
to ignition. The top of the piston forms the floor of the combustion chamber. A
rod connects the bottom of the piston to the crankshaft. Lubricated bearings
enable both ends of the connecting rod to pivot, transferring the piston’s
vertical motion into the crankshaft’s rotational force, or torque. The pistons’
motion rotates the crankshaft at speeds ranging from about 600 to thousands of
revolutions per minute (rpm), depending on how much fuel is delivered to the
cylinders.
Fuel vapor enters and
exhaust gases leave the combustion chamber through openings in the cylinder
head controlled by valves. The typical engine valve is a metal shaft with a
disk at one end fitted to block the opening. The other end of the shaft is
mechanically linked to a camshaft, a round rod with odd-shaped lobes located
inside the engine block or in the cylinder head. Inlet valves open to allow
fuel to enter the combustion chambers. Outlet valves open to let exhaust gases
out.
A gear wheel, belt, or
chain links the camshaft to the crankshaft. When the crankshaft forces the
camshaft to turn, lobes on the camshaft cause valves to open and close at
precise moments in the engine’s cycle. When fuel vapor ignites, the intake and
outlet valves close tightly to direct the force of the explosion downward on
the piston.
B
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Engine Types
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The blocks in most internal-combustion
engines are in-line designs or V designs. In-line designs are arranged so that the
cylinders stand upright in a single line over the crankshaft. In a V design,
two rows of cylinders are set at an angle to form a V. At the bottom of the V
is the crankshaft. In-line configurations of six or eight cylinders require
long engine compartments found more often in trucks than in cars. The V design
allows the same number of cylinders to fit into a shorter, although wider,
space. Another engine design that fits into shorter, shallower spaces is a
horizontally opposed, or flat, arrangement in which the crankshaft lies between
two rows of cylinders.
Engines become more powerful,
and use more fuel, as the size and number of cylinders increase. Most modern
vehicles in the United States have 4-, 6-, or 8-cylinder engines, but car
engines have been designed with 1, 2, 3, 5, 12, and more cylinders.
Diesel engines, common in large
trucks or buses, are similar to gasoline internal-combustion engines, but they
have a different ignition system. Diesels compress air inside the cylinders
with greater force than a gasoline engine does, producing temperatures hot
enough to ignite the diesel fuel on contact. Some cars have rotary engines,
also known as Wankel engines, which have one or more elliptical chambers in
which triangular-shaped rotors, instead of pistons, rotate.
Electric motors have been
used to power automobiles since the late 1800s. Electric power supplied by
batteries runs the motor, which rotates a driveshaft, the shaft that transmits
engine power to the axles. Commercial electric car models for specialized
purposes were available in the 1980s. General Motors Corporation introduced a
mass-production all-electric car in the mid-1990s.
Automobiles that combine two or
more types of engines are called hybrids. A typical hybrid is an electric motor
with batteries that are recharged by a generator run by a small gas- or
diesel-powered engine. These hybrids are known as hybrid electric vehicles
(HEVs). By relying more on electricity and less on fuel combustion, HEVs have
higher fuel efficiency and emit fewer pollutants. Several automakers have
experimented with hybrids.
In 1997 Toyota Motor Corporation
became the first to mass-produce a hybrid vehicle, the Prius. It became
available in Japan in 1997 and in North America in 2000. The first hybrid
available for sale in North America, the Honda Insight, was offered by Honda
Motor Co., Ltd., in 1999. Honda later introduced a hybrid version of the Honda
Civic. In August 2004 the Ford Motor Company became the first U.S. automaker to
release a hybrid vehicle when it began production of the Ford Escape Hybrid,
the first hybrid sport- utility vehicle (SUV). The Escape Hybrid was released
for the 2005 model year.
C
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Fuel Supply
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Fuel-Injection System
The fuel-injection system replaces the
carburetor in most new vehicles to provide a more efficient fuel delivery
system. Electronic sensors respond to varying engine speeds and driving
conditions by changing the ratio of fuel to air. The sensors send a fine mist
of fuel from the fuel supply through a fuel-injection nozzle into a combustion
chamber, where it is mixed with air. The mixture of fuel and air triggers
ignition.
The internal-combustion engine is
powered by the burning of a precise mixture of liquefied fuel and air in the
cylinders’ combustion chambers. Fuel is stored in a tank until it is needed,
then pumped to a carburetor or, in newer cars, to a fuel-injection system.
The carburetor controls the
mixture of gas and air that travels to the engine. It mixes fuel with air at
the head of a pipe, called the intake manifold, leading to the cylinders. A
vacuum created by the downward strokes of pistons draws air through the
carburetor and intake manifold. Inside the carburetor, the airflow transforms
drops of fuel into a fine mist, or vapor. The intake manifold delivers the fuel
vapor to the cylinders, where it is ignited.
All new cars produced today
are equipped with fuel injection systems instead of carburetors. Fuel injectors
spray carefully calibrated bursts of fuel mist into cylinders either at or near
openings to the combustion chambers. Since the exact quantity of gas needed is
injected into the cylinders, fuel injection is more precise, easier to adjust,
and more consistent than a carburetor, delivering better efficiency, gas
mileage, engine responsiveness, and pollution control. Fuel-injection systems
vary widely, but most are operated or managed electronically.
High-performance automobiles are
often fitted with air-compressing equipment that increases an engine’s output.
By increasing the air and fuel flow to the engine, these features produce
greater horsepower. Superchargers are compressors powered by the crankshaft.
Turbochargers are turbine-powered compressors run by pressurized exhaust gas.
D
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Exhaust System
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The exhaust system carries
exhaust gases from the engine’s combustion chamber to the atmosphere and
reduces, or muffles, engine noise. Exhaust gases leave the engine in a pipe,
traveling through a catalytic converter and a muffler before exiting through
the tailpipe.
Chemical reactions inside the
catalytic converter change most of the hazardous hydrocarbons and carbon
monoxide produced by the engine into water vapor and carbon dioxide.
The conventional muffler is an
enclosed metal tube packed with sound-deadening material. Most conventional
mufflers are round or oval-shaped with an inlet and outlet pipe at either end.
Some contain partitions to help reduce engine noise.
Car manufacturers are
experimenting with an electronic muffler, which uses sensors to monitor the
sound waves of the exhaust noise. The sound wave data are sent to a computer
that controls speakers near the tailpipe. The system generates sound waves 180
degrees out of phase with the engine noise. The sound waves from the electronic
muffler collide with the exhaust sound waves and they cancel each other out,
leaving only low-level heat to emerge from the tailpipe.
E
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Cooling and Heating System
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Combustion inside an engine
produces temperatures high enough to melt cast iron. A cooling system conducts
this heat away from the engine’s cylinders and radiates it into the air.
In most automobiles, a
liquid coolant circulates through the engine. A pump sends the coolant from the
engine to a radiator, which transfers heat from the coolant to the air. In
early engines, the coolant was water. In most automobiles today, the coolant is
a chemical solution called antifreeze that has a higher boiling point and lower
freezing point than water, making it effective in temperature extremes. Some
engines are air cooled, that is, they are designed so a flow of air can reach
metal fins that conduct heat away from the cylinders.
A second, smaller radiator
is fitted to all modern cars. This unit uses engine heat to warm the interior
of the passenger compartment and supply heat to the windshield defroster.
III
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DRIVETRAIN
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The rotational force of the
engine’s crankshaft turns other shafts and gears that eventually cause the
drive wheels to rotate. The various components that link the crankshaft to the
drive wheels make up the drivetrain. The major parts of the drivetrain include
the transmission, one or more driveshafts, differential gears, and axles.
A
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Transmission
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Automatic Transmission System
The automatic transmission is one of the
key components of an automobile. Located just behind the engine, the
transmission changes the speed and power ratios between the engine and the
driving wheels of a vehicle.
The transmission, also known as
the gearbox, transfers power from the engine to the driveshaft. As the engine’s
crankshaft rotates, combinations of transmission gears pass the energy along to
a driveshaft. The driveshaft causes axles to rotate and turn the wheels. By
using gears of different sizes, a transmission alters the rotational speed and
torque of the engine passed along to the driveshaft. Higher gears permit the
car to travel faster, while low gears provide more power for starting a car
from a standstill and for climbing hills.
The transmission usually is
located just behind the engine, although some automobiles were designed with a
transmission mounted on the rear axle. There are three basic transmission
types: manual, automatic, and continuously variable.
A manual transmission has a
gearbox from which the driver selects specific gears depending on road speed
and engine load. Gears are selected with a shift lever located on the floor
next to the driver or on the steering column. The driver presses on the clutch
to disengage the transmission from the engine to permit a change of gears. The
clutch disk attaches to the transmission’s input shaft. It presses against a
circular plate attached to the engine’s flywheel. When the driver presses down
on the clutch pedal to shift gears, a mechanical lever called a clutch fork and
a device called a throwout bearing separate the two disks. Releasing the clutch
pedal presses the two disks together, transferring torque from the engine to
the transmission.
An automatic transmission
selects gears itself according to road conditions and the amount of load on the
engine. Instead of a manual clutch, automatic transmissions use a hydraulic
torque converter to transfer engine power to the transmission.
Instead of making distinct
changes from one gear to the next, a continuously variable transmission uses
belts and pulleys to smoothly slide the gear ratio up or down. Continuously
variable transmissions appeared on machinery during the 19th century and on a
few small-engine automobiles as early as 1900. The transmission keeps the
engine running at its most efficient speed by more precisely matching the gear
ratio to the situation. Commercial applications have been limited to small
engines.
B
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Front- and Rear-Wheel Drive
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Differential
The gears of a differential allow a
car's powered wheels to rotate at different speeds as the car turns around
corners. The car's drive shaft rotates the crown wheel, which in turn rotates
the half shafts leading to the wheels. When the car is traveling straight
ahead, the planet pinions do not spin, so the crown wheel rotates both wheels
at the same rate. When the car turns a corner, however, the planet pinions spin
in opposite directions, allowing one wheel to slip behind and forcing the other
wheel to turn faster.
Depending on the vehicle’s
design, engine power is transmitted by the transmission to the front wheels,
the rear wheels, or to all four wheels. The wheels receiving power are called
drive wheels: They propel the vehicle forward or backward. Most automobiles
either are front-wheel or rear-wheel drive. In some vehicles, four-wheel drive
is an option the driver selects for certain road conditions; others feature
full-time, all-wheel drive.
The differential is a gear
assembly in an axle that enables each powered wheel to turn at different speeds
when the vehicle makes a turn. The driveshaft connects the transmission’s output
shaft to a differential gear in the axle. Universal joints at both ends of the
driveshaft allow it to rotate as the axles move up and down over the road
surface.
In rear-wheel drive, the
driveshaft runs under the car to a differential gear at the rear axle. In
front-wheel drive, the differential is on the front axle and the connections to
the transmission are much shorter. Four-wheel-drive vehicles have drive shafts
and differentials for both axles.
IV
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SUPPORT SYSTEMS
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Automobiles would deliver
jolting rides, especially on unpaved roads, without a system of shock absorbers
and other devices to protect the auto body and passenger compartment from
severe bumps and bounces.
A
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Suspension System
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The suspension system, part of
the undercarriage of an automobile, contains springs that move up and down to
absorb bumps and vibrations. In one type of suspension system, a long tube, or
strut, has a shock absorber built into its center section. Shock absorbers
control, or dampen, the sudden loading and unloading of suspension springs to
reduce wheel bounce and the shock transferred from the road wheels to the body.
One shock absorber is installed at each wheel. Modern shock absorbers have a
telescoping design and use oil, gas, and air, or a combination to absorb
energy.
Luxury sedans generally have a
soft suspension for comfortable riding. Sports cars and sport-utility vehicles
have firmer suspensions to improve cornering ability and control over rough terrain.
Older automobiles were equipped
with one-piece front axles attached to the frame with semielliptic leaf
springs, much like the arrangement on horse-drawn buggies. Front wheels on
modern cars roll independently of each other on half-shafts instead of on a
common axle. Each wheel has its own axle and suspension supports, so the shock
of one wheel hitting a bump is not transferred across a common axle to the
other wheel or the rest of the car. Many rear-axle suspensions for automobiles
and heavier vehicles use rigid axles with coil or leaf springs. However,
advanced passenger cars, luxury sedans, and sports cars feature independent
rear-wheel suspension systems.
Active suspensions are
computer-controlled adjustments of the downward force of each wheel as the
vehicle corners or rides over uneven terrain. Sensors, a pump, and hydraulic
cylinders, all monitored and controlled by computer, enable the vehicle to lean
into corners and compensate for the dips and dives that accompany emergency
stops and rapid acceleration.
B
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Wheels and Tires
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Wheels support the vehicle’s
weight and transfer torque to the tires from the drivetrain and braking
systems. Automobile wheels generally are made of steel or aluminum. Aluminum
wheels are lighter, more impact absorbent, and more expensive.
Pneumatic (air-filled) rubber tires,
first patented in 1845, fit on the outside rims of the wheels. Tires help
smooth out the ride and provide the automobile’s only contact with the road, so
traction and strength are primary requirements. Tire treads come in several
varieties to match driving conditions.
V
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CONTROL SYSTEMS
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A driver controls the
automobile’s motion by keeping the wheels pointed in the desired direction, and
by stopping or slowing the speed at which the wheels rotate. These controls are
made possible by the steering and braking systems. In addition, the driver
controls the vehicle’s speed with the transmission and the gas pedal, which
adjusts the amount of fuel fed to the engine.
A
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Steering
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Automobiles are steered by
turning the front wheels, although a few automobile types have all-wheel
steering. Most steering systems link the front wheels together by means of a
tie-rod. The tie-rod insures that the turning of one wheel is matched by a
corresponding turn in the other.
When a driver turns the
steering wheel, the mechanical action rotates a steering shaft inside the
steering column. Depending on the steering mechanism, gears or other devices
convert the rotating motion of the steering wheel into a horizontal force that
turns the wheels.
Manual steering relies only on
the force exerted by the driver to turn the wheels. Conventional power steering
uses hydraulic pressure, operated by the pressure or movement of a liquid, to
augment that force, requiring less effort by the driver. Electric power
steering uses an electric motor instead of hydraulic pressure.
B
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Brakes
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Disc and Drum Brakes
Disc and drum brakes create friction to
slow the wheels of a motor vehicle. When a driver presses on the brake pedal of
a vehicle, brake lines filled with fluid transmit the force to the brakes. In a
disc brake, the fluid pushes the brake pads in the caliper against the rotor,
slowing the wheel. In a drum brake, the fluid pushes small pistons in the brake
cylinder against the hinged brake shoes. The shoes pivot outward and press
against a drum attached to the wheel to slow the wheel.
Brakes enable the driver to
slow or stop the moving vehicle. The first automobile brakes were much like
those on horse-drawn wagons. By pulling a lever, the driver pressed a block of
wood, leather, or metal, known as the shoe, against the wheel rims. With sufficient
pressure, friction between the wheel and the brake shoe caused the vehicle to
slow down or stop. Another method was to use a lever to clamp a strap or brake
shoes tightly around the driveshaft.
A brake system with shoes
that pressed against the inside of a drum fitted to the wheel, called drum
brakes, appeared in 1903. Since the drum and wheel rotate together, friction
applied by the shoes inside the drum slowed or stopped the wheel. Cotton and
leather shoe coverings, or linings, were replaced by asbestos after 1908,
greatly extending the life of the brake mechanism. Hydraulically assisted
braking was introduced in the 1920s. Disk brakes, in which friction pads clamp
down on both sides of a disk attached to the axle, were in use by the 1950s.
An antilock braking system
(ABS) uses a computer, sensors, and a hydraulic pump to stop the automobile’s
forward motion without locking the wheels and putting the vehicle into a skid.
Introduced in the 1980s, ABS helps the driver maintain better control over the
car during emergency stops and while braking on slippery surfaces.
Automobiles are also equipped
with a hand-operated brake used for emergencies and to securely park the car,
especially on uneven terrain. Pulling on a lever or pushing down on a foot pedal
sets the brake.
VI
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ELECTRICAL SYSTEM
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The automobile depends on
electricity for fuel ignition, headlights, turn signals, horn, radio,
windshield wipers, and other accessories. A battery and an alternator supply
electricity. The battery stores electricity for starting the car. The
alternator generates electric current while the engine is running, recharging
the battery and powering the rest of the car’s electrical needs.
Early automotive electrical
systems ran on 6 volts, but 12 volts became standard after World War II
(1939-1945) to operate the growing number of electrical accessories.
Eventually, 24- or 48-volt systems may become the standard as more computers
and electronics are built into automobiles.
A
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Ignition System
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Ignition System
The ignition system delivers voltage to
ignite the fuel in the automotive vehicle. When the ignition switch is turned
on, low-voltage electric current flows from the battery to the coil, which
converts the current to high-voltage. The current then flows to the
distributor, which delivers it to each of the spark plugs. The spark plugs send
an igniting spark to the fuel/air mixture in the combustion chambers.
The ignition system supplies
high-voltage current to spark plugs to ignite fuel vapor in the cylinders.
There are many variations, but all gasoline-engine ignition systems draw
electric current from the battery, significantly increase the current’s
voltage, then deliver it to spark plugs that project into the combustion
chambers. An electric arc between two electrodes at the bottom of the spark
plug ignites the fuel vapor.
In older vehicles, a distributor,
which is an electrical switching device, routes high-voltage current to the
spark plugs. The distributor’s housing contains a switch called the breaker
points. A rotating shaft in the distributor causes the switch to open and
close, interrupting the supply of low-voltage current to a transformer called a
coil. The coil uses electromagnetic induction (see Electricity: Electromagnetism)
to convert interruptions of the 12-volt current into surges of 20,000 volts or
more. This high-voltage current passes back to the distributor, which
mechanically routes it through wires to spark plugs, producing a spark that
ignites the gas vapor in the cylinders. A condenser absorbs excess current and
protects the breaker points from damage by the high-voltage surge. The
distributor and other devices control the timing of the spark-plug discharges.
In modern ignition systems,
the distributor, coil, points, and condenser have been replaced by solid-state
electronics controlled by a computer. A computer controls the ignition system
and adjusts it to provide maximum efficiency in a variety of driving
conditions.
VII
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SAFETY FEATURES
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Manufacturers continue to build
lighter vehicles with improved structural rigidity and ability to protect the
driver and passengers during collisions.
Bumpers evolved as rails or
bars to protect the front and rear of the car’s body from damage in minor
collisions. Over the years, bumpers became stylish and, in some cases, not
strong enough to survive minor collisions without expensive repairs.
Eventually, government regulations required bumpers designed to withstand
low-speed collisions with less damage. Some bumpers can withstand 4-km/h (2.5-mph)
collisions with no damage, while others can withstand 8-km/h (5-mph) collisions
with no damage.
Modern vehicles feature crumple
zones, portions of the automobile designed to absorb forces that otherwise
would be transmitted to the passenger compartment. Passenger compartments on
many vehicles also have reinforced roll bar structures in the roof, in case the
vehicle overturns, and protective beams in the doors to help protect passengers
from side impacts.
Seat belt and upper-body
restraints that relax to permit comfort but tighten automatically during an
impact are now common. Some car models are equipped with shoulder-restraint
belts that slide into position automatically when the car’s doors close.
An air bag is a high-speed
inflation device hidden in the hub of the steering wheel or in the dash on the
passenger’s side. Some automobiles have side-impact air bags, located in doors
or seats. At impact, the bag inflates almost instantaneously. The inflated bag
creates a cushion between the occupant and the vehicle’s interior. Air bags
first appeared in the mid-1970s, available as an optional accessory. Today they
are installed on all new passenger cars sold in the United States.
Air bags inflate with great
force, which occasionally endangers a child or infant passenger. Some newer
automobile models are equipped with switches to disable the passenger-side air
bags when a child or infant is traveling in the passenger seat. Automakers
continue to research ways to make air-bag systems less dangerous for frail and
small passengers, yet effective in collisions.
VIII
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HISTORY
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Horseless Carriage
The original horseless carriage was
introduced in 1893 by brothers Charles and Frank Duryea. It was America’s first
internal-combustion motor car, and it was followed by Henry Ford’s first
experimental car that same year.
The history of the automobile
actually began about 4,000 years ago when the first wheel was used for
transportation in India. In the early 15th century the Portuguese arrived in
China and the interaction of the two cultures led to a variety of new
technologies, including the creation of a wheel that turned under its own
power. By the 1600s small steam-powered engine models had been developed, but
it was another century before a full-sized engine-powered vehicle was created.
In 1769 French Army officer
Captain Nicolas-Joseph Cugnot built what has been called the first automobile.
Cugnot’s three-wheeled, steam-powered vehicle carried four persons. Designed to
move artillery pieces, it had a top speed of a little more than 3.2 km/h (2
mph) and had to stop every 20 minutes to build up a fresh head of steam.
Henry Ford with Quadricycle
Henry Ford and his wife, Clara, sit in a
Quadricycle, the first automobile produced by Ford, in 1896. In this later
photograph, their grandson, Henry Ford II, stands at the side.
As early as 1801 successful
but very heavy steam automobiles were introduced in England. Laws barred them
from public roads and forced their owners to run them like trains on private
tracks. In 1802 a steam-powered coach designed by British engineer Richard
Trevithick journeyed more than 160 km (100 mi) from Cornwall to London. Steam
power caught the attention of other vehicle builders. In 1804 American inventor
Oliver Evans built a steam-powered vehicle in Chicago, Illinois. French
engineer Onésiphore Pecqueur built one in 1828.
British inventor Walter Handcock
built a series of steam carriages in the mid-1830s that were used for the first
omnibus service in London. By the mid-1800s England had an extensive network of
steam coach lines. Horse-drawn stagecoach companies and the new railroad
companies pressured the British Parliament to approve heavy tolls on
steam-powered road vehicles. The tolls quickly drove the steam coach operators
out of business.
During the early 20th
century steam cars were popular in the United States. Most famous was the
Stanley Steamer, built by American twin brothers Freelan and Francis Stanley. A
Stanley Steamer established a world land speed record in 1906 of 205.44 km/h
(121.573 mph). Manufacturers produced about 125 models of steam-powered
automobiles, including the Stanley, until 1932.
A
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Internal-Combustion Engine
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Development of lighter steam
cars during the 19th century coincided with major developments in engines that
ran on gasoline or other fuels. Because the newer engines burned fuel in
cylinders inside the engine, they were called internal-combustion engines.
In 1860 French inventor
Jean-Joseph-Étienne Lenoir patented a one-cylinder engine that used kerosene
for fuel. Two years later, a vehicle powered by Lenoir’s engine reached a top
speed of about 6.4 km/h (about 4 mph). In 1864 Austrian inventor Siegfried
Marcus built and drove a carriage propelled by a two-cylinder gasoline engine.
American George Brayton patented an internal-combustion engine that was
displayed at the 1876 Centennial Exhibition in Philadelphia, Pennsylvania.
In 1876 German engineer
Nikolaus August Otto built a four-stroke gas engine, the most direct ancestor
to today’s automobile engines. In a four-stroke engine the pistons move down to
draw fuel vapor into the cylinder during stroke one; in stroke two, the pistons
move up to compress the vapor; in stroke three the vapor explodes and the hot
gases push the pistons down the cylinders; and in stroke four the pistons move
up to push exhaust gases out of the cylinders. Engines with two or more
cylinders are designed so combustion occurs in one cylinder after the other
instead of in all at once. Two-stroke engines accomplish the same steps, but
less efficiently and with more exhaust emissions.
Automobile manufacturing began in
earnest in Europe by the late 1880s. German engineer Gottlieb Daimler and
German inventor Wilhelm Maybach mounted a gasoline-powered engine onto a
bicycle, creating a motorcycle, in 1885. In 1887 they manufactured their first
car, which included a steering tiller and a four-speed gearbox. Another German
engineer, Karl Benz, produced his first gasoline car in 1886. In 1890 Daimler
and Maybach started a successful car manufacturing company, The Daimler Motor
Company, which eventually merged with Benz’s manufacturing firm in 1926 to
create Daimler-Benz. The joint company makes cars today under the Mercedes-Benz
nameplate (see DaimlerChrysler AG).
In France, a company called
Panhard-Levassor began making cars in 1894 using Daimler’s patents. Instead of
installing the engine under the seats, as other car designers had done, the
company introduced the design of a front-mounted engine under the hood.
Panhard-Levassor also introduced a clutch and gears, and separate construction
of the chassis, or underlying structure of the car, and the car body. The
company’s first model was a gasoline-powered buggy steered by a tiller.
French bicycle manufacturer
Armand Peugeot saw the Panhard-Levassor car and designed an automobile using a
similar Daimler engine. In 1891 this first Peugeot automobile paced a 1,046-km
(650-mi) professional bicycle race between Paris and Brest. Other French
automobile manufacturers opened shop in the late 1800s, including Renault. In
Italy, Fiat (Fabbrica Italiana Automobili di Torino) began building cars in
1899.
American automobile builders
were not far behind. Brothers Charles Edgar Duryea and James Frank Duryea built
several gas-powered vehicles between 1893 and 1895. The first Duryea, a
one-cylinder, four-horsepower model, looked much like a Panhard-Levassor model.
In 1893 American industrialist Henry Ford built an internal-combustion engine
from plans he saw in a magazine. In 1896 he used an engine to power a vehicle
mounted on bicycle wheels and steered by a tiller.
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Early Electric Cars
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For a few decades in the
1800s, electric engines enjoyed great popularity because they were quiet and
ran at slow speeds that were less likely to scare horses and people. By 1899 an
electric car designed and driven by Belgian inventor Camille Jenatzy set a
record of 105.8810 km/h (65.79 mph).
Early electric cars featured
a large bank of storage batteries under the hood. Heavy cables connected the
batteries to a motor between the front and rear axles. Most electric cars had
top speeds of 48 km/h (30 mph), but could go only 80 km (50 mi) before their
batteries needed recharging. Electric automobiles were manufactured in quantity
in the United States until 1930.
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AUTOMOBILES IN THE 20TH CENTURY
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For many years after the
introduction of automobiles, three kinds of power sources were in common use:
steam engines, gasoline engines, and electric motors. In 1900 more than 2,300
automobiles were registered in New York City; Boston, Massachusetts; and
Chicago, Illinois. Of these, 1,170 were steam cars, 800 were electric cars, and
only 400 were gasoline cars. Gasoline-powered engines eventually became the
nearly universal choice for automobiles because they allowed longer trips and
faster speeds than engines powered by steam or electricity.
But development of gasoline
cars in the early 1900s was hindered in the United States by legal battles over
a patent obtained by New York lawyer George B. Selden. Selden saw a gasoline
engine at the Philadelphia Centennial Exposition in 1876. He then designed a
similar one and obtained a broad patent that for many years was interpreted to
apply to all gasoline engines for automobiles. Although Selden did not
manufacture engines or automobiles, he collected royalties from those who did.
Henry Ford believed Selden’s
patent was invalid. Selden sued when Ford refused to pay royalties for Ford-manufactured
engines. After eight years of court battles, the courts ruled in 1911 that
Selden’s patent applied only to two-stroke engines. Ford and most other
manufacturers were using four-stroke engines, so Selden could not charge them
royalties.
Improvements in the operating
and riding qualities of gasoline automobiles developed quickly after 1900. The
1902 Locomobile was the first American car with a four-cylinder, water-cooled,
front-mounted gasoline engine, very similar in design to most cars today.
Built-in baggage compartments appeared in 1906, along with weather resistant
tops and side curtains. An electric self-starter was introduced in 1911 to
replace the hand crank used to start the engine turning. Electric headlights
were introduced at about the same time.
Most automobiles at the
turn of the 20th century appeared more or less like horseless carriages. In
1906 gasoline-powered cars were produced that had a style all their own. In
these new models, a hood covered the front-mounted engine. Two kerosene or
acetylene lamps mounted to the front served as headlights. Cars had fenders
that covered the wheels and step-up platforms called running boards, which
helped passengers get in and out of the vehicle. The passenger compartment was
behind the engine. Although drivers of horse-drawn vehicles usually sat on the
right, automotive steering wheels were on the left in the United States.
In 1903 Henry Ford incorporated
the Ford Motor Company, which introduced its first automobile, the Model A, in
that same year. It closely resembled the 1903 Cadillac, which was hardly
surprising since Ford had designed cars the previous year for the Cadillac
Motor Car Company. Ford’s company rolled out new car models each year, and each
model was named with a letter of the alphabet. By 1907, when models R and S
appeared, Ford’s share of the domestic automobile market had soared to 35
percent.
Ford’s famous Model T
debuted in 1908 but was called a 1909 Ford. Ford built 17,771 Model T’s and
offered nine body styles. Popularly known as the Tin Lizzy, the Model T became
one of the biggest-selling automobiles of all time. Ford sold more than 15
million before stopping production of the model in 1927. The innovative
assembly-line method used by the company to build its cars was widely adopted
in the automobile industry.
By 1920 more than 8 million
Americans owned cars. Major reasons for the surge in automobile ownership were
Ford’s Model T, the assembly-line method of building it, and the affordability
of cars for the ordinary wage earner.
Improvements in engine-powered
cars during the 1920s contributed to their popularity: synchromesh
transmissions for easier gear shifting; four-wheel hydraulic brake systems;
improved carburetors; shatterproof glass; balloon tires; heaters; and mechanically
operated windshield wipers.
From 1930 to 1937, automobile
engines and bodies became large and luxurious. Many 12- and 16-cylinder cars
were built. Independent front suspension, which made the big cars more
comfortable, appeared in 1933. Also introduced during the 1930s were stronger,
more reliable braking systems, and higher-compression engines, which developed
more horsepower. Mercedes introduced the world’s first diesel car in 1936.
Automobiles on both sides of the Atlantic were styled with gracious
proportions, long hoods, and pontoon-shaped fenders. Creative artistry merged
with industrial design to produce appealing, aerodynamic automobiles.
Some of the first vehicles
to fully incorporate the fender into the bodywork came along just after World War
II, but the majority of designs still had separate fenders with pontoon shapes
holding headlight assemblies. Three companies, Ford, Nash, and Hudson Motor Car
Company, offered postwar designs that merged fenders into the bodywork. The
1949 Ford was a landmark in this respect, and its new styling was so well
accepted the car continued in production virtually unchanged for three years,
selling more than 3 million. During the 1940s, sealed-beam headlights, tubeless
tires, and the automatic transmission were introduced.
Two schools of styling
emerged in the 1950s, one on each side of the Atlantic. The Europeans continued
to produce small, light cars weighing less than 1,300 kg (2,800 lb). European
sports cars of that era featured hand-fashioned aluminum bodies over a steel
chassis and framework.
In America, automobile designers
borrowed features for their cars that were normally found on aircraft and
ships, including tailfins and portholes. Automobiles were produced that had
more space, more power, and smoother riding capability. Introduction of power
steering and power brakes made bigger cars easier to handle. The Buick Motor
Car Company, Olds Motor Vehicle Company (Oldsmobile), Cadillac Automobile
Company, and Ford all built enormous cars, some weighing as much as 2,495 kg
(5,500 lb).
The first import by German
manufacturer Volkswagen AG, advertised as the Beetle, arrived in the United
States in 1949. Only two were sold that year, but American consumers soon began
buying the Beetle and other small imports by the thousands. That prompted a
downsizing of some American-made vehicles. The first American car called a
compact was the Nash Rambler. Introduced in 1950, it did not attract buyers on
a large scale until 1958. More compacts, smaller in overall size than a
standard car but with virtually the same interior body dimensions, emerged from
the factories of many major manufacturers. The first Japanese imports, 16
compact trucks, arrived in the United States in 1956.
In the 1950s new automotive
features were introduced, including air conditioning and electrically operated
car windows and seat adjusters. Manufacturers changed from the 6-volt to the
12-volt ignition system, which gave better engine performance and more reliable
operation of the growing number of electrical accessories.
By 1960 sales of foreign
and domestic compacts accounted for about one-third of all passenger cars sold
in the United States. American cars were built smaller, but with increased
engine size and horsepower. Heating and ventilating systems became standard
equipment on even the least expensive models. Automatic transmissions, power
brakes, and power steering became widespread. Styling sometimes prevailed over
practicality—some cars were built in which the engines had to be lifted to allow
simple service operations, like changing the spark plugs. Back seats were
designed with no legroom.
In the 1970s American
manufacturers continued to offer smaller, lighter models in addition to the
bigger sedans that led their product lines, but Japanese and European compacts
continued to sell well. Catalytic converters were introduced to help reduce
exhaust emissions.
During this period, the
auto industry was hurt by the energy crisis, created when the Organization of
Petroleum Exporting Countries (OPEC), a cartel of oil-producing countries, cut
back on sales to other countries. The price of crude oil skyrocketed, driving
up the price of gasoline. Large cars were getting as little as 8 miles per
gallon (mpg), while imported compacts were getting as much as 35 mpg. More
buyers chose the smaller, more fuel-efficient imports.
Digital speedometers and
electronic prompts to service parts of the vehicle appeared in the 1980s.
Japanese manufacturers opened plants in the United States. At the same time,
sporty cars and family minivans surged in popularity.
Advances in automobile
technology in the 1980s included better engine control and the use of
innovative types of fuel. In 1981 Bayerische Motoren Werke AG (BMW) introduced
an on-board computer to monitor engine performance. A solar-powered vehicle,
SunRaycer, traveled 3,000 km (1,864 mi) in Australia in six days.
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NEW TECHNOLOGIES
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A
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Antipollution Strategies
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Pollution-control laws adopted at the
beginning of the 1990s in some of the United States and in Europe called for
automobiles that produced better gas mileage with lower emissions. The
California Air Resources Board required companies with the largest market
shares to begin selling vehicles that were pollution free—in other words,
electric. In 1996 General Motors became the first to begin selling an
all-electric car, the EV1, to California buyers. The all-electric cars
introduced so far have been limited by low range, long recharges, and weak consumer
interest.
Engines that run on hydrogen
have been tested. Hydrogen combustion produces only a trace of harmful
emissions, no carbon dioxide, and a water-vapor by-product. However, technical
problems related to the gas’s density and flammability remain to be solved.
Diesel engines burn fuel
more efficiently, and produce fewer pollutants, but they are noisy. Popular in
trucks and heavy vehicles, diesel engines are only a small portion of the
automobile market. A redesigned, quieter diesel engine introduced by Volkswagen
in 1996 may pave the way for more diesels, and less pollution, in passenger
cars.
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Hybrid-Electric Vehicles (HEVs)
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Hybrid Car Structure
Hybrid cars combine advantages of both
gasoline-powered cars and electric cars. Click on the labels to learn more
about the different parts of hybrid cars.
While some developers searched
for additional alternatives, others investigated ways to combine electricity
with liquid fuels to produce low-emissions power systems. The hybrid-electric
vehicle (HEV) uses both an electric motor or motors and a gasoline or diesel
engine that charges the batteries in order to extend the distance that the
vehicle can travel without having to recharge the batteries. An HEV at a
stoplight typically sits silent, burning no fuel and making no pollution, if
the batteries are sufficiently charged. If driven slowly, as in heavy traffic,
the vehicle might move only on electric power. Only when more power is demanded
for acceleration or to move a heavy load, does the gasoline or diesel engine
come into play.
Two automobiles with such
hybrid engines, the Toyota Prius and the Honda Insight, became available in the
late 1990s. The Prius hit automobile showrooms in Japan in 1997, selling 30,000
models in its first two years of production. The Prius became available for
sale in North America in 2000. The Honda Insight debuted in North America in
late 1999. Both vehicles promised to double the fuel efficiency of conventional
gasoline-powered cars while significantly reducing toxic emissions. The Ford
Motor Company introduced the first U.S.-made hybrid when it began production
for the Ford Escape Hybrid in August 2004. The 2005 model year Escape was also
the first hybrid in the sport-utility vehicle (SUV) category. Electric Car.
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Computers and Navigation Devices
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Computer control of automobile
systems increased dramatically during the 1990s. The central processing unit
(CPU) in modern engines manages overall engine performance. Microprocessors
regulating other systems share data with the CPU. Computers manage fuel and air
mixture ratios, ignition timing, and exhaust-emission levels. They adjust the
antilock braking and traction control systems. In many models, computers also
control the air conditioning and heating, the sound system, and the information
displayed in the vehicle’s dashboard.
Expanded use of computer
technology, development of stronger and lighter materials, and research on
pollution control will produce better, “smarter” automobiles. In the 1980s the
notion that a car would “talk” to its driver was science fiction; by the 1990s
it had become reality.
Onboard navigation was one of
the new automotive technologies in the 1990s. By using the satellite-aided
global positioning system (GPS), a computer in the automobile can pinpoint the
vehicle’s location within a few meters. The onboard navigation system uses an
electronic compass, digitized maps, and a display screen showing where the
vehicle is relative to the destination the driver wants to reach. After being
told the destination, the computer locates it and directs the driver to it,
offering alternative routes if needed.
Some cars now come equipped
with GPS locator beacons, enabling a GPS system operator to locate the vehicle,
map its location, and if necessary, direct repair or emergency workers to the
scene.
Cars equipped with computers
and cellular telephones can link to the Internet to obtain constantly updated
traffic reports, weather information, route directions, and other data. Future
built-in computer systems may be used to automatically obtain business
information over the Internet and manage personal affairs while the vehicle’s
owner is driving.
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Other Improvements
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During the 1980s and 1990s,
manufacturers trimmed 450 kg (1,000 lb) from the weight of the typical car by
making cars smaller. Less weight, coupled with more efficient engines, doubled
the gas mileage obtained by the average new car between 1974 and 1995. Further
reductions in vehicle size are not practical, so the emphasis has shifted to
using lighter materials, such as plastics, aluminum alloys, and carbon
composites, in the engine and the rest of the vehicle.
Looking ahead, engineers are devising
ways to reduce driver errors and poor driving habits. Systems already exist in
some locales to prevent intoxicated drivers from starting their vehicles. The
technology may be expanded to new vehicles. Anticollision systems with sensors
and warning signals are being developed. In some, the car’s brakes
automatically slow the vehicle if it is following another vehicle too closely.
New infrared sensors or radar systems may warn drivers when another vehicle is
in their “blind spot.”
Catalytic converters work only
when they are warm, so most of the pollution they emit occurs in the first few
minutes of operation. Engineers are working on ways to keep the converters warm
for longer periods between drives, or heat the converters more rapidly.
Gas-Electric Hybrids
The Toyota Prius, top, a four-seat
hybrid electric vehicle (HEV), was the first HEV to be marketed when Toyota
introduced it in Japan in 1997. The Honda Insight, bottom, a two-seat HEV,
followed in 1999 when it was sold in both Japan and the United States. The
Prius had its U.S. debut in 2000.
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