Engine At Work Essay, Research Paper
Engine at Work
Have you ever wondered how a car s engine works? Most of today s automobile engines run on gasoline, which is also known as an internal combustion engine. Many factors are involved in getting an engine to run properly spark plug, valves, piston, piston rings, combustion chamber, connecting rod, crankshaft, and oil sump. A car s engine can be one of the most complicated mechanisms a person can own and yet it s one of the easiest to use (Romans 104).
As Fullerton quoted, The purpose of a gasoline car engine is to convert gasoline into motion so that the car can move (432). Currently, the easiest way to create motion from gasoline is to burn the gasoline inside an engine+generally referred to as an internal combustion engine. Almost all cars today use a reciprocating internal combustion engine. Thiessen and Dales state that A reciprocating internal combustion engine is relatively efficient compared to an external combustion engine, relatively inexpensive compared to a gas turbine and relatively easy to refuel compared to an electric car (45). Because of these technological advantages, an internal combustion engine is the best candidate for making a car run.
The basic idea behind a reciprocating internal combustion engine works similarly to that of an old Revolutionary War cannon. In the old days, these cannons were stuffed with gunpowder and loaded with cannon ball. When the wick of the cannon was lit, the cannon ball was propelled through the air for a distance. In a reciprocating internal combustion engine, gasoline is pumped into the engine. A device called a piston replaces the cannon ball. The piston is connected to the crankshaft by a connecting rod. As the crankshaft revolves, it has the effect of “resetting the cannon.” So the piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder full of air and gasoline during the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work. Then the piston moves back up to compress this fuel and air mixture. Compression makes the explosion more powerful. When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down. Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder where it goes out the tail pipe. The motion that comes out of an internal combustion engine is rotational, compared to the motion produced by a cannon ball, which is straight. In an engine, the linear motion is converted into a rotational motion by the crankshaft (fig. 1).
The core of the engine is the cylinder. The piston moves up and down inside the cylinder. The engine described in figure 1 has one cylinder, which is typical of most gas powered RC (remote controlled) cars and lawn mowers. However, most cars we drive have more than one cylinder (four, six and eight cylinders are common). In a multi-cylinder engine, the cylinders usually are arranged in one of three ways: inline (fig. 2), V shaped (fig.3) or flat (fig 4). Crouse and Anglin states that Different configurations have different smoothness, manufacturing-cost and shape characteristics that make them more suitable in some vehicles (96).
The spark plug supplies the spark that ignites the air and fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly. The intake and exhaust valves open at the proper time to let in air and fuel, and to let out exhaust. Both valves are closed during compression and combustion so that the combustion chamber is sealed. A piston is a cylindrical piece of metal that moves up and down inside the cylinder. The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. The crankshaft turns the pistons in an up and down motion into circular motion similar to that of a crank on a jack-in-the-box. The oil sump surrounds the crankshaft and contains some amount of oil, which collects in the bottom of the oil sump.
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes: they keep exhaust in the combustion chamber from leaking into the sump during compression and combustion, and they keep oil in the sump from leaking into the combustion area, where it would be burned and lost. The combustion chamber is the area where compression and combustion take place. As the piston moves up and down, the size of the combustion chamber changes back and forth from maximum to minimum volume.
The engine has come a long way ever since it originated from the steam engine. Once only used in locomotive trains, today the engine is used in many complex things from helicopters to racecars. The engine, most commonly used to quickly get from one place to another, is constantly being improved upon by engineers to make human transportation better. Perhaps in the future, a form of transportation will be to beam a person from one place to another like they do in Star Trek . Until that day comes, the engine is one off the greatest forms of transportation.
Crouse, William H and Donald L. Anglin. The Auto Book. 3rd ed. San Francisco: McGraw-Hill, 1976.
Thiessen, Frank and Davis Dales. Automotive Principles and Service. 2nd ed. Reston, Virginia: Reston, 1984.
Fullerton, Robert C. Engine Systems Testing and Diagnosis. Crystal Lake, Illinois: Sun, 1979.
Brain, Marshall. How Car Engine Works. 16 Oct. 2000
Romans, Brent. Engine Upgrades for Less Than $500. Super Street. 27 Jan 1998: 87-89.