The Four-Stroke Internal Combustion Engine

Title: The Four-Stroke Internal Combustion Engine

Specific Purpose: To inform the audience about the history of the four-stroke engine, how it works and some brief information to other types of engines.

Thesis Statement: Internal combustion engines are very important to today's society, the four stroke engine is the most popular and important due to it long history of achievement and durability.

I. Introduction

1. Attention getter- Imagine life without the engine, to be more specific the four-stroke engine or basic car engine. Everyday tasks, like coming to school, would know turn into journeys through the snow ,up a hill, both ways. All this because no-one ever invented this engine that helps transport most people today through all kinds of weather and other obstacles.

2. Ethos- Four-stroke engines have been around since the 1870's and are known, as well as used, everywhere today. I have been working on and around cars for about 6 years now, having seen many different engine types the four-stroke has definitely been one of the top performing engines. And although some of the engineers who design these engines don't take into account how hard they make the engines to fix for the mechanics I can still see the importance of having the four-stroke engine as a transportation device, plus it is one of the easier engines to work on.

3. Preview- There are a few key pieces of information that I wanted to go over with you today. First, a look at the history of the four-stroke engine, after that I will try my best to describe how the basic four-stroke works like one found in most cars today. Also there will be a quick overview of some other engine types.

Transition- So let's take a step back so we can get a better understanding of this engine by taking a look at it's history.

II. Body

1. In1876 the German engineer Nikolaus A. Otto invented the first ever four-stroke engine. It was nicknamed the "Otto" and was used in a moped type bicycle.

A. Otto used the theories of French engineer Alphonse Beau de Rochas to invent his engine.

B. This engine was a great success, selling more than 50,000 man-made models in 17 years, the "Otto" engine came to the U.S. in 1878.

C. After Otto's former associates invented a carburetor that allowed the use of gasoline as fuel, a German mechanical engineer called Carl Benz then used the combination of the "Otto" engine with the carburetor to make the first ever car.

Transition- Now that everyone has a little background on our basic four-stroke gasoline engine, we can now go on to how it works.

2. All four stroke engines, no matter who makes them or what they are used for, they all need certain basic parts and they all work in the same fashion.

A. Some parts that all the engines need include the following. A intake valve, that allows fuel to come in A exhaust valve , where all the burnt fuel goes out. A camshaft turns the valves to open or close. The spark plug that ignites the fuel in the cylinder using a small spark. The burning fuel always pushes the piston down with enough force to bring it back up in a reciprocationg motion which is then transferred into a rotating motion by a crankshaft.

B. Now let's go over the four cycles or strokes:

1. Intake: Piston goes down, intake valve opens to suck fuel and air using the atmospheric pressure caused by the piston going down.

2. Compression: Piston is pushed up by the revolving crankshaft, closing the intake valve and compressing the fuel and air mixture.

3. Power: As the piston reaches the top of the cylinder the spark plug emits a spark igniting the compressed fuel/air mixture, with the great increase in pressure the piston causes the crankshaft to rotate using the piston