4 Cycle Internal Combustion Engine – Fuel System

    Published: 06-16-2009
    Views: 42,504
    Adam Kemp, the Energy Systems Lab Director at Thomas Jefferson High School for Science and Technology discusses how an Internal Combustion Engine works including an illustration of four of the main components that make up the fuel system in an Internal Combustion engine.

    Adam Kemp: Hi, I am Adam Kemp, and today we are learning about Internal Combustion engines. For this clip, I am going to talk about the fuel systems that delivers fuel and air to power the engine. To start off, I am going to illustrate four of the main components that make up the fuel system in an Internal Combustion engine. The first component I am going to talk about is the air filter. The air filter acts as a barrier between outside elements and the inside of the engine. It filters out particulates and impurities that might damage the engine during it's operation. The second component I am going to illustrate is the Gas tank. The Gas take access the reservoir of fuel, that's used to deliver the gasoline into the carburetor during its operation. This gas tank happens to be a gravity feed gas tank, due to the fact that this engine does not have a fuel pump, it relies on the earth's gravity to bring fuel from the gas tank into the carburetor. The third component I am going to talk about is the carburetor. The carburetor is a device that's going to mix a proper mixture of fuel and air and then deliver it to the combustion chamber of the engine. The carburetor is actually quite simple device that acts much like an air brush if you are familiar. Inside the carburetor is a little tube that extends from the reservoir which houses a little bit of gasoline to the internal chamber of the carburetor where air blows through. When the air comes in to the carburetor, it blows over this tube, sucks gas in to the chamber and vaporizes it, mixing it into the gas and air mixture required for in combustion. At the back of the carburetor, we have a butterfly valve which is used to regulate the amount of gas and air entering the engine. As the butterfly valve opens and closes, increasingly, more air and gas enter the combustion chamber, thus increasing the speed of the engine. On the back side of the butterfly valve, we see a little adjustment screw which regulates the idle speed of the engine. If we look inside the carburetor, we will see two main components. The first component we see is this brass disk which is used to regulate the flow of gasoline into the carburetor. If this flow were not inside the carburetor, gas would continuously flow from the gas tank in to the carburetor, overflowing it and flooding the engine. If we remove the float, we will see that there is a little valve beneath it that accesses this regulating device. At the base of the carburetor is the inlet for the gasoline to flow up and into the carburetor where it is vaporized by the incoming air. Another feature this carburetor has is a priming pump. The priming pump is used to pump gasoline from the gas tank into the carburetor during long periods of storage. Sometimes if the engine is stored for long period of time, gasoline will leave the carburetor, evaporate or run back into the gas tank. In this case, the priming pump is used to manually move the gasoline back into the carburetor and get it ready for starting.

    The final component of this fuel system is the muffler assembly. The muffler is used to resonate the sound energy that is emanated during the combustion process of the engine. Inside of the muffler are a series of baffles that resonate that energy before the gases are left or dispersed into the atmosphere. This muffler assemble also comes with a heat shield to prevent yourself from burning, in case you brush against the engine. Coming up next is a clip on how to prime and start your Internal Combustion engine.

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