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Basic Car Knowledge: The Internal Combustion Engine

August 25th, 2010

internal-combustion-engine.jpgThe internal combustion engine has been around since the 1800s and is still used to power almost every car on the road today, although alternative forms of power such as electricity are becoming more popular. Since it was first used to power an automobile, the internal combustion engine has continuously been modified and redesigned to produce a high power output while using only small amount of fuel.

A car’s engine needs three key things to create power: fuel, air, and spark. Looking at the big picture, a car’s engine is nothing more than a highly efficient air pump. Fuel and air are injected into the cylinder combustion chamber and then compressed by the rising cylinder before being ignited by the spark plug. The ignition of the fuel/air mixture by the spark plug forces the piston downward, creating the power that drives your car. The cylinders of the engine fire continuously in a specific order. The engine converts the downward motion of the cylinders into a twisting force called torque which is transferred to the rest of the car via the flywheel. The flywheel is a circular disk attached to the back of the engine that transfers the power to the transmission.

The next question to be answered is how air and fuel get in and out of the engine. This is accomplished through the use of a complex valve system and a timing belt or chain. Depending on the type of car, the engine may have two or four valves per cylinder. Even if there are four valves per cylinder, there are only two types of valves (two of each if there are four valves); intake and exhaust valves. The intake valves open to allow air to enter the combustion chamber and mix with the fuel. The exhaust valves open to allow air to exit after combustion has taken place. The valves are opened and closed by a component called a camshaft. The camshaft is a rod with various lobes that spins in the cylinder head while the engine is running. The lobes push up on rocker arms which open and close valves in sequence with the engine’s firing order. This is where the timing belt comes in.

If you own a car, you’ve probably heard the term timing belt thrown around, and you may know that most cars require it to be replaced around 100,000 miles. The timing belt is the most important component of the engine because it controls when air enters and leaves the engine. The timing must be extremely precise for the engine to function properly. The timing belt is located on the front of the engine and is usually behind a timing cover to keep dirt out. The timing belt controls the motion of three gears: the crankshaft gear, and the two camshaft gears located at the front of each cylinder head. The timing belt ensures that the camshafts open and close all the valves at the correct time and sequence according to the position of the cylinders and crankshaft in the engine.

The internal combustion engine is a very complex system, and only the basic aspects of its operation were discussed in this article. There are countless different designs of the internal combustion engine, all of which are constantly being modified to achieve high power output and fuel efficiency.

This article was supplied by Erich Shuman from Constant Content.

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