Guest Author - William Charles Vetter
Suck, Squish, Bang and Blow.
No this is not an X rated article, but rather a simplified description of how an internal combustion engine works. The basic way all internal combustion engines work is to suck in a mixture of fuel and air, compress it, ignite it either with a spark plug or by self-ignition (in the case of a diesel engine), allow the explosion of combusting gasses to force the piston back down and then expel the exhaust gas. The vertical movement of the piston is converted into rotary motion of the crank shaft via connecting rods. The crank then goes out to the transmission via a flywheel and clutch, and the transmission sends the rotary motion to the wheels, driving the vehicle forwards.
The engine found under the hood in every production car ever made is commonly known as an internal combustion engine. A great deal has changed as far as engine components, computer management, fuel delivery and power transmission but the basic principle behind the internal combustion engine has not. At the very heart of the power plant we find the engine block which has vertical holes or cylinders through it in which pistons shaped like tuna cans go up and down. At the very bottom of the block running lengthwise there is a crank shaft that works very much like the pedals of a bicycle, each of the pistons is connected to the crank via a connecting rod which functions like your leg pushing the pedal down around and back up again.
The most common internal combustion engine is known as a four stroke engine. It cycles like this: The first down stroke causes a vacuum in the cylinder, intake valve (s) in the head at the top of the cylinder open to allow a metered amount of gasoline and air into the cylinder, as the piston nears the bottom of the stroke the intake valves (s) close. The second up stroke compresses this air fuel mixture as the piston nears the top the spark plug sparks and ignites this highly volatile gas. The third down stroke is the power stroke forcing the piston down with the force of the explosion. The fourth up stroke is the exhaust stroke, the exhaust valve(s) in the head at the top of the closed cylinder open and the burned gasses are forced out through the valves to the exhaust manifold and out of the tail pipe at the rear of the car, and the entire cycle starts over with stroke one again. Cars have multiples of cylinders and each of the pistons in the engine are at various strokes so there is always one or more pistons generating power driving the others.
The gasoline we buy at the pump generates the heat energy that moves our cars forward. A gallon of gasoline contains potential energy equivalent to approximately 31.5 million calories of heat. One calorie is the amount of energy required to raise one gram of water one degrees Celsius. Remember once again Newton’s first law of thermal dynamics, “Energy cannot be created or destroyed only its form can be changed”. One half of the energy from the combustion is changed into kinetic energy in the form of your car moving forward, one fourth goes out of the tail pipe and one fourth must be removed by your engine cooling systems radiator or heater. Despite over one hundred years of advancements and research and development the basic internal combustion engine still runs most of our motorcycles, cars, trucks, busses, lawnmowers and leaf blowers.
