Automotive engine

An automotive engine is a machine that powers a ground-based vehicle, typically a car or truck. In the twenty-first century, automotive engines may take several forms and styles, but most have similar parts, such as pistons, cylinders, camshafts, crankshafts, and transmissions. Most automotive engines also follow closely related principles. The major uniting principle in most modern automotive engines is the property of internal combustion, meaning that the engine’s energy comes from small explosions, most commonly created by gasoline, that take place inside the engine. (A significant and increasing number of automobiles are powered by electricity, but the machines that propel them are typically considered motors rather than engines.)

Background

Automotive engines are machines that propel vehicles such as cars and trucks. Although these engines may take different shapes and sizes, their main commonality is that they create their substantial power through internal combustion. Internal combustion is a scientific process that allows people to create and transfer energy by igniting small amounts of powerful fuel, such as gasoline.

When gasoline or a similar fuel is ignited in an enclosed space, it produces a powerful burst of expanding gas, a form of energy. A modern internal combustion engine uses this principle through a system of moving parts and small explosions that occur hundreds of times each minute. The explosions push the moving parts, allowing their energy to be transferred to other parts of the mechanism. Eventually, the energy is transferred to the gears that turn the car wheels and move the vehicle forward.

Overview

An automotive engine is a large, heavy, complex structure containing dozens of smaller parts, all carefully fitted for optimal and synchronized use. The largest part of an engine is a block-like structure called the engine block, which contains hollow cylinders and a revolving bar called the crankshaft. Above the engine block is a smaller, rectangular structure called the cylinder head, which contains a revolving bar called the camshaft as well as a complex series of ports and valves that allow fuel, air, and exhaust to move into and out of the engine. The engine block and cylinder head help to organize and support the many moving parts of the engine as well as to protect them.

One of the most basic but most important parts of an automotive engine is the piston, a heavy metal tube that can move up and down within a hollow cylinder. The motions of a piston, in either direction, are known as strokes. Most automotive engines are configured to use a four-stroke cycle, which completes the process of creating and distributing energy over the course of four piston movements.

The first stroke in the cycle occurs when the piston moves downward. This downward motion sucks a mixture of fuel (typically gasoline) and air through an intake port and into the top of the hollow cylinder. The intake port closes and the piston makes its second stroke, moving back upward to compress the air-fuel mix tightly against the top of the cylinder. This compression is important to strengthening the energy that will be produced.

A spark next occurs at the top of the cylinder, igniting the compressed mixture of fuel and air. The resulting explosion of energy creates expanding gas that pushes the piston back to the bottom of the cylinder, thus generating the third stroke. As the piston pushes downward, the energy transfers along a pivoting connecting rod to the crankshaft, a revolving bar beneath the cylinders, and from there may be transferred to other parts of the engine.

Finally, the fourth stroke occurs when the piston moves up again to the top of the cylinder. This time, it pushes the gaseous residue of the combustion, known as exhaust, through an exit called the exhaust port. From there, the exhaust will be moved through the engine until it can be safely released, typically through a tailpipe under the body of the vehicle.

Each piston in an engine is designed to undergo the stroke cycle at high speeds, potentially hundreds of times per minute. However, the significant power necessary to propel a large vehicle requires the use of multiple pistons operating at the same time. In most large vehicle engines, pistons are arranged in side-by-side rows. They take turns firing, or going through their strokes, to supply the rest of the machine with a consistent supply of power.

Many automobiles have four cylinders, each housing one piston. However, larger or more powerful engines may feature other configurations. Some vehicles have six cylinders, frequently three on each side that are angled inward into a V shape. This is called a V6 engine. Vehicles with eight cylinders are often arranged in the same way, and are referred to as having V8 engines. Vehicles are often marketed based on V6, V8, and similar distinctions that help to indicate their level of engine power.

Although the pistons are considered the powerhouses of an engine, many other parts are required to keep them working optimally. Revolving metal bars above the pistons and cylinders, called camshafts, allow oval-shaped gears called cams to turn in sync with the up-and-down motion of the pistons. These cams regulate the opening and closing of valves and ports that allow air and fuel into the cylinders and then let exhaust escape after each combustion.

At the end of the camshaft are cam gears that turn a timing belt, which links the camshaft to the crankshaft located below the cylinders. The crankshaft is a revolving bar under the pistons that helps to balance the pistons and to receive and transfer the mechanical energy produced by the pistons. The timing belt allows the camshaft and crankshaft to work in perfect coordination with the piston strokes, thus creating a single, unified, highly efficient process that creates and transfers energy as quickly as possible.

The crankshaft also connects to a flywheel that connects the aforementioned engine parts to the transmission. The transmission is a machine that works alongside, and as part of, the overall workings of the engine. In short, the transmission contains the gears for the car that help it regulate the energy produced in the engine and the resulting speed and behavior of the vehicle. Most car transmissions contain five or six sets of gears, along with belts or chains that connect the gears. Via a complex process, these gears connect the driver’s controls, mainly the gas pedal, with the engine to ensure that the vehicle is getting the amount of power it needs to work correctly.

Transmissions may be manual, meaning they are controlled by the driver’s commands, or automatic, meaning they are regulated by a computer in the engine. Automatic transmissions are widely popular and more common in modern automotive engines, but many drivers prefer the hands-on control over car performance afforded by manual transmissions.

In general, transmissions seek to balance the speed and acceleration of the vehicle so that the engine produces the lowest amount of power to meet the driver’s needs. This ensures that the engine does not go so fast that its gears or other structures risk damaging themselves, and that the car uses its fuel in a controlled way rather than simply burning it all quickly. The transmission also helps the driver moderate the speed of the vehicle, which contributes greatly to road safety and ease of use. Transmissions are critical for modern cars. Without transmissions, vehicles would be hard to start, stop, or control in any way.

Aside from all of these mechanical devices, automotive engines need certain additional materials to operate smoothly. One is air, which is fed into the engine from outside and run through a filter before being piped into the engine. Air helps to increase the power of the combustions as well as remove the exhaust afterward.

The other crucial input into the engine is fuel, typically gasoline, which travels to the engine via a pipeline from the fuel tank that is usually located toward the rear of the vehicle. The fuel is propelled by a pump near the tank and run through a fuel filter near the base of the engine before it is released into the ports above the cylinders. Fuel injectors are precisely tuned sprayers that insert the correct amount of fuel into each cylinder when necessary; too much or too little could lead to serious mechanical problems or even dangers.

Automotive engines, like other machines, generate heat as they operate. To counter this, modern automotive engines feature powerful cooling systems. These systems pipe chemicals known as antifreeze through the engine to regulate the temperature. The hot engine generally significantly increases the temperature of the antifreeze, which then cycles out of the engine into the radiator to be cooled by fans. Once cooled, the antifreeze can be recirculated through the engine. A thermostat monitors the temperature and regulates the amount of antifreeze needed in the engine versus what is being cooled in the radiator.

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