2 Stroke & 4-Stroke Cycle Engines

    Published: 06-16-2009
    Views: 58,364
    Adam Kemp, the Energy Systems Lab Director at Thomas Jefferson High School for Science and Technology discusses how an Internal Combustion Engine works including the two different types of Internal Combustion engines – 2 stroke and 4 stroke.

    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 two different types of Internal Combustion engines. The first type is a two-cycle engine. Typically, you will Two-cycle engines in Radio controlled vehicles, small scale applications and some types of lawn tools including chain-saws. The Second type of engine is a Four-cycle engine where you will find them from anywhere from a Go-kart engine to a Lawn mover engine, all the way up to the standard Internal Combustion engine in your vehicle. To start off, I am going to talk about a two-cycle engine. Unlike a four cycle engine, two cycle engines use a fuel-oil mix due to the fact that they do not have an oil reservoir. To start, the piston rises and produces a vacuum below the piston that sucks in a fuel-air mixture in to the crankcase. When the piston falls, it pressurizes the fuel-air mixture in the crankcase and injects it in to the combustion chamber. Due to the centrifugal force of this process, the piston rises again and pressurizes the fuel-air mixture until it is combusted with either a glow plug or a spark plug. This pushes the piston back down, the exhaust gases are released and the process repeats itself.

    Four-cycle engines are a more common type of engine, ranging from a lawn mover engines up to an automobile engine. During the first cycle, the piston drops and produces a vacuum, sucking in gas and air mixture in to the combustion chamber. Then the piston rises, compressing the gas and air mixture until it is ignited by the spark plug. This pushes the piston back down during the power stroke and produces enough force to cycle the piston up again during the fourth cycle. Finally, the piston rises and pushes the exhaust gases out of the combustion chamber. Coming up next is an overview of the individual sub-systems of the Internal Combustion engine.

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