All About Automobiles

Valve Mechanism

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A valve mechanism is a group of components that
opens and closes the intake and exhaust valves in
the cylinder head at the appropriate timing.
Crankshaft
Timing sprocket
Timing chain
Intake camshaft
Intake valve
Exhaust camshaft
Exhaust valve
* The diagram shows a VVT-i system valve
mechanism.

Intake stroke

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The exhaust valve closes and the intake valve
opens. The downward stroke of the piston causes
the air-fuel mixture to be drawn into the cylinder
from the open intake valve

Exhaust stroke

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The exhaust valve opens as the piston is about to
complete its downward stroke. Then, the exhaust
gases that result from the combustion are
discharged outside of the cylinder

Compression stroke

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The piston completes its downward stroke and the
intake valve closes. The air-fuel mixture that is
drawn into the cylinder becomes highly
compressed with the upward stroke of the piston

Combustion stroke

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When the piston is about to complete its upward
stroke, current flows to the spark plug, thus
creating a spark. This is then followed by the
combustion of the compressed air-fuel mixture and
an explosion. This explosion pushes the piston
downward, causing the crankshaft to rotate

Hybrid vehicle

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This type of vehicle is equipped with different types
of motive power, such as a gasoline engine and an
electric motor. Because the gasoline engine
generates electricity, this type of vehicle does not
require an external source for recharging the
battery. System of wheel driver uses 270V, on the
other hand, other electric 12V.
For example, during start- off, it uses an electric
motor that produces high power despite a low
speed. When the vehicle picks up speed, it
operates the gasoline engine that is more efficient
at higher speeds. By making the best use of both
types of motive force in this manner, it is effective
in reducing exhaust emission and improving fuel
economy.

Fuel cell hybrid vehicle (FCHV)

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This electric vehicle uses the electric energy that is
created when the hydrogen fuel reacts with the
oxygen in the air to form water. Because it emits
only water, this is considered to be the ultimate
form of low- pollution vehicle, and is anticipated to
become the motive power for the next generation.
• The diagram indicates Toyota fuel cell hybrid
system.
Power control unit
Electric motor
Fuel cell stack
Hydrogen storage system
Secondary battery

Electric vehicle (EV)

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This vehicle uses the power of the batteries to
operate the electric motor. Instead of using fuel, the
batteries require recharging. It offers many
advantages, including zero emissions and low
noise during operation. System of wheel drive uses
290V, on the other hand, other electric 12V.
• The diagram indicates Toyota EV system.
Power control unit
Electric motor
Battery

Diesel engine vehicle

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This type of vehicle runs on an engine that uses
diesel fuel. Because diesel engines produce large
torque and offer good fuel economy, they are
widely used in trucks and SUVs.
SUV: Sports Utility Vehicle
Engine
Fuel tank (diesel fuel)

Classification by Drive Method

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Vehicles can be classified by the position of the
engine and drive wheels, and the number of drive
wheels.
FF (Front-engine, Front-drive)
Because a FF vehicle does not have a propeller
shaft, a spacious interior can be realized, thus
achieving excellent comfort.
FR (Front-engine, Rear-drive)
Because a FR vehicle has a good weight
balance, it excels in controllability and stability.
MR (Midship-engine, Rear-drive)
Because a MR vehicle has a good weight
balance on the front and rear axles, it excels in
controllability.
4WD (4-Wheels Drive)
Because a 4WD vehicle drives with four
wheels, it can operate under poor conditions in
a stable manner. Its weight is greater than that
of other types of vehicles.

Gasoline engine vehicle

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This type of vehicle runs on an engine that uses
gasoline fuel. Because gasoline engines produce
high power yet come in a compact package, they
are widely used in passenger vehicles.
Similar engines are also used on the CNG engine,
the LPG engine and alcohol engine, which use
different types of fuel.
CNG: Compressed Natural Gas
LPG: Liquefied Petroleum Gas
Engine
Fuel tank (gasoline)

Master Cylinder

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The master cylinder displaces hydraulic brake fluid under pressure to the rest of the brake system. When the brake pedal is depressed, the push rod moves the primary piston forward in the cylinder. The hydraulic pressure created and the force of the primary piston spring moves the secondary piston forward. When the forward movement of the pistons causes their primary cups to cover the bypass holes, hydraulic pressure builds up and is transmitted to the wheel cylinders. When the pedal retracts, the pistons allow fluid from the reservoir to fill the chamber if needed. Special sensors within the master cylinder are used to monitor the level of the fluid in the reservoir, and to alert the driver if a pressure imbalance develops. The standard dual master cylinder gives the front and rear brakes separate hydraulic systems. If a brake fluid leak occurs in one system, the other system will still operate, making it possible to stop the car.

FUEL SUPPLY

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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.

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.© Microsoft Corporation. All

ENGINE.

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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.

Crash/Safety Features

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What actually happens in a collision? The first part of that answer is that there are two collisions. The first collision occurs when the vehicle runs into another object. The second collision is when the occupant(s) hit the inside of the car. Neither a seat belt nor an air bag can do anything about the first collision, but they can be a great help to you in the second collision. They can minimize the impact between you and the interior of the car. Safety belt use is more than a personal right. Injuries and fatalities resulting from motor vehicle accidents are reflected in the rising costs of auto and health insurance, and costs to employers in the form of lost days at work. The taxpayer also loses by having to support emergency medical response teams and social programs for the disabled. Excuses, excuses! 1. "Seat belts are too uncomfortable." Of course, in a car accident -- without your seat belt -- you would smash into the steering column, slam into the dashboard, or crash through the windshield. This too, can be very uncomfortable. 2. "Seat belts wrinkle my clothes." Sometimes. Sitting also wrinkles clothes. Wearing clothes wrinkles clothes. Flying through a windshield REALLY wrinkles clothes. 3. "Only nerds wear seat belts." Really? It turns out that -- without seat belts -- nerds, jocks, cheerleaders, "A" students and average students would all fly through the windshield at the same rate. 4. "I'm a good driver." Nice as that is, good drivers can get hit by bad drivers, drunk drivers, or other good drivers with mechanical failures. Very few people intend to have accidents. 5. "Seat belts restrict my freedom of movement." This is true. Without your seat belt, you have all the freedom in the world -- to crash into your windshield, to slam into your car's interior, or to be thrown from your car and slide along the pavement. Freedom is great. 6. "It's too embarrassing to ask friends to use their seat belts." In 1984, 46,000 people died in car accidents. That same year, not one person died of embarrassment. Safety in car design was recognized as being important even in the earliest cars. In recent years, however, it has become a fundamental subject in its own right. Active safety measures have been designed to reduce the likelihood of a car being involved in an accident in the first place, while passive safety measures assume that a collision is inevitable and then aim to reduce the severity of the injuries to the road users involved. Until the late 1800's the British had a 2 mph speed limit for cars. There was an excellent reason for this. It was also required, for safety's sake, that each car carry two passengers with a third person walking in front. The job of the third person was to walk in front of the car to warn everyone that it was coming!

Brake Bands

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A brake band is made of steel, and has a friction lining. One end of the band is attached a servo actuating rod. A servo actuating rod is a hydraulic piston (a cylinder with a piston inside it) that is open at one end to allow oil to flow in. The piston is normally in the released position because it's kept that way by a spring. However, when pressurized oil is sent to the cylinder, the oil forces the piston forward. This causes the brake band to tighten, and this locks the brake.

BRAKE

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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.

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.

Bleeder Valves

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Since the brake system is filled with fluid, it must be occasionally "bled" or the old fluid released in order to install new fluid. It is also occasionally necessary to remove air bubbles that get into the system if any of the parts are changed. Disc brakes, drum brakes and all hydraulic brakes have bleeder valves next to the slave pistons. These are opened when the system is being bled and brake fluid flows out as well as air bubbles. When the brake fluid is coming out without any air bubbles, the mechanic seals the bleeder valve and tops off the brake fluid reservoir. Bleeder valves can also be found on the side of the reservoir. These are used for the same purpose; getting air bubbles out of the master cylinder assembly. If you have air bubbles in your fluid, your pedal will feel softer than normal, and braking power will be reduced, so it is a good idea to have your brakes bled and the fluid changed according to your owner's manual.

Air Compressor.

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Air Compressor, also air pump, machine that decreases the volume and increases the pressure of a quantity of air by mechanical means. Air thus compressed possesses great potential energy, because when the external pressure is removed, the air expands rapidly. The controlled expansive force of compressed air is used in many ways and provides the motive force for air motors and tools, including pneumatic hammers, air drills, sandblasting machines, and paint sprayers. See Compressed Air.
Air compressors are of two general types: reciprocating and rotating. In a reciprocating, or displacement, compressor which is used to produce high pressures, the air is compressed by the action of a piston in a cylinder. When the piston moves to the right, air flows into the cylinder through the intake valve; when the piston moves to the left, the air is compressed and forced through an output-control valve into a reservoir or storage tank.
A rotating air compressor used for low and medium pressures, usually consists of a bladed wheel or impeller that spins inside a closed circular housing. Air is drawn in at the center of the wheel and accelerated by the centrifugal force of the spinning blades. The energy of the moving air is then converted into pressure in the diffuser, and the compressed air is forced out through a narrow passage to the storage tank.

As air is compressed it is also heated. Air molecules tend to collide more often with each other in a smaller space, and the energy produced by these collisions is evident as heat. This heat is undesirable in the compression process, so the air may be cooled on the way to the reservoir by circulating air or water. For high-pressure compressed air, several stages of compression may be employed, with the air being further compressed in each cylinder and cooled before each stage.

also Heating, Ventilating, and Air Conditioning; Heat Transfer; Pump.

TWO-STROKE ENGINES

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By suitable design it is possible to operate an Otto-cycle or diesel as a two-stroke or two-cycle engine with a power stroke every other stroke of the piston instead of once every four strokes. The power of a two-stroke engine is usually double that of a four-stroke engine of comparable size.

The general principle of the two-stroke engine is to shorten the periods in which fuel is introduced to the combustion chamber and in which the spent gases are exhausted to a small fraction of the duration of a stroke instead of allowing each of these operations to occupy a full stroke. In the simplest type of two-stroke engine, the poppet valves are replaced by sleeve valves or ports (openings in the cylinder wall that are uncovered by the piston at the end of its outward travel). In the two-stroke cycle, the fuel mixture or air is introduced through the intake port when the piston is fully withdrawn from the cylinder. The compression stroke follows, and the charge is ignited when the piston reaches the end of this stroke. The piston then moves outward on the power stroke, uncovering the exhaust port and permitting the gases to escape from the combustion chamber.

Turbo Charger How It Works

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The turbocharger is bolted to the exhaust manifold of the engine. The exhaust from the cylinders spins the turbine, which works like a gas turbine engine. The turbine is connected by a shaft to the compressor, which is located between the air filter and the intake manifold. The compressor pressurizes the air going into the pistons.
The exhaust from the cylinders passes through the turbine blades, causing the turbine to spin. The more exhaust that goes through the blades, the faster they spin.
On the other end of the shaft that the turbine is attached to, the compressor pumps air into the cylinders. The compressor is a type of centrifugal pump -- it draws air in at the center of its blades and flings it outward as it spins.
In order to handle speeds of up to 150,000 rpm, the turbine shaft has to be supported very carefully. Most bearings would explode at speeds like this, so most turbochargers use a fluid bearing. This type of bearing supports the shaft on a thin layer of oil that is constantly pumped around the shaft. This serves two purposes: It cools the shaft and some of the other turbocharger parts, and it allows the shaft to spin without much friction.
There are many tradeoffs involved in designing a turbocharger for an engine. In the next section, we'll look at some of these compromises and see how they affect performance.

Valve Seals

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The valve seal is a unit that goes over the end of the valve stem. It keeps excess oil from getting between the valve guide and the valve stem.

Shocking Developments

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The first electric-powered road vehicle is believed to have been built in Scotland about 1839 by Robert Anderson, but it, along with others within the next several years, were generally unsuccessful. The steamer had to wait for a boiler to build up pressure and was very noisy besides. The concept of an electrical engine that could start immediately and run quietly was very attractive at that time. There were disadvantages, however. Electric batteries were heavy, bulky, unreliable, and needed recharging after a short run. In 1880, there was a general improvement in the development of longer-lasting batteries. There still existed, however, excessive weight and bulk of the batteries and a need for frequent rechargings, although electric cabs appeared on the streets of London in the late 1800s. Steamers and electric vehicles gained only restricted acceptance on the continent as well. In France, the electric had a shining, brief hour of public acclaim when Camille Jenatzy, driving a Jeantaud electric, pushed the cigar-shaped vehicle to a record of sixty miles per hour on April 29, 1899. The high-speed run, however, burned out the specially fabricated batteries and the interest in electrics died almost as soon as the cheers of the attending public. It was in America that steamers and electric cars gained their most sustained measure of success. Eventually twenty different U.S. car companies would produce electrics; and in the peak of popularity, 1912, nearly 35,000 were operating on American roads. But even America could not shake the limitations of the bulky batteries and the short ranges between recharging. Steamers were actually more popular. More than 100 American plants were making steamers, the most famous of which were the Stanley brothers factory in Newton, Massachusetts. The "Stanley Steamer" had the affectionate nickname, "The Flying Teapot," and with good reason. In 1906, a Stanley Steamer was clocked at 127.6 miles per hour on the sands of Ormond Beach, Florida. In spite of this, the steamers, along with the electrics, were only living on borrowed time. Experiments were being made on an automobile powered by a gasoline-fueled, internal-combustion engine, and the steamers and electrics would not survive the impact of the coming collision. Internal-combustion automobiles did not just burst forth on the scene all of a sudden to crowd the electrics and steamers off the road. The theories of internal-combustion engines had been on the way ever since 1860, when Etienne Lenoir applied to the authorities in Paris for a patent on his invention, an internal-combustion engine powered by coal gas. Two years later, Lenoir hooked his engine to a carriage, and, although it was crude, it worked. It worked so poorly and so slowly (about one mile an hour), however, that he became discouraged and abandoned his efforts. In 1864, a resourceful Austrian in Vienna, Siegfried Marcus, built a one-cylinder engine that incorporated a crude carburetor and a magneto arrangement to create successive small explosions that applied alternating pressure against the piston within the cylinder. Bolting his engine to a cart, Siegfried geared the piston to the rear wheels, and while a strong assistant lifted the rear of the cart off the ground, Siegfried started the engine. The wheels began to turn and continued to turn with each successive "pop." Marcus signaled the assistant to lower the cart and watched it burp along for about 500 feet before it ran out of fuel. Ten years later, he built the new, improved version of his motorcar, and then, mysteriously washed his hands of the entire thing, saying it was a waste of time. (The second model, which is preserved in an Austrian museum, was refurbished and taken for a test run in Vienna in 1950. It reached a top speed of ten miles per hour on level ground.) Although Lenoir and Marcus did not have the grit and determination to pursue their enterprises, they made some valuable contributions to the theory of internal-combustion engines. It would be overstating the case to credit them with the creation of the internal-combustion automobile, however.

Semiconductors and Diodes

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Semiconductors are made from material somewhere between the ranges of conductors and nonconductors. Semiconductors, basically, are designed to do one of three things: (1) stop the flow of electrons, (2) start the flow of electrons, or (3) control the amount of electron flow. A semiconductor diode is a two-element solid state electronic device. It contains what is termed a "P" type material connected to a piece of "N" material. The union of the "P" and "N" materials forms a PN junction with two connections. The "anode" is connected to the P material; the "cathode" is connected to the N material. A diode is, in effect, a one-way valve. It will conduct current in one direction and remain non conductive in the reverse direction. When current flows through the diode, it is said to be "forward biased." When current flow is blocked by the diode, it is "reverse biased." When a diode is reverse biased, there is an extremely small current flow; actually, the current flow is said to be "negligible." When the P and N are fused together to form a diode, it can be placed in a circuit. The P material is connected to the positive side of the battery and the N material is connected to the negative side of the battery. Connected in this manner, current will flow. If connected in the reverse manner, current will not flow.

Worm and Tapered Peg Steering

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The manual worm and tapered peg steering gear has a three-turn worm gear at the lower end of the steering shaft supported by ball bearing assemblies. The pitman shaft has a lever end with a tapered peg that rides in the worm grooves. When the movement of the steering wheel revolves the worm gear, it causes the tapered peg to follow the worm gear grooves. Movement of the peg moves the lever on the pitman shaft which in turn moves the pitman arm and the steering linkage.