Sunday, September 26, 2010

Four Cycle Internal Combustion Engine Basics

If you're a seasoned Mechanic this information is old but I'm starting from scratch for the neophyte Mechanics and laymen who just want to know more about what drives the wheels on their vehicle. This video demonstrates the operation of a 4 cycle internal combustion engine. In this case it's a Deutz Gas Engine.

With any gas or diesel engine you still need a timed rotation of engine parts to make it happen. The double overhead cam in the video is run off a timing chain. The gears are aligned to open and close the valves at a specific time to match the rotation of each piston. If you watch you can see the 4 cycle process that makes combustion occur in each cylinder.

It's really sweet to watch and as you can see the timing has to be accurate for proper combustion to happen. With that being said when it's time to change your timing belt or chain you need to follow through with this. Your owner's manual will tell you when this operation is due.

The 4 cycles are as follows:

 Intake Stroke - The piston is on a downstroke & draws in a mixture of Fuel: controlled by the fuel injector and Air: controlled by the engine intake valves.

 Compression Stroke - The piston moves upwards and compresses the air fuel mixture. The compressed mixture is ready to explode once the high energy spark is delivered.

Power Stroke - At the top of the piston's stroke and at a specific point, spark occurs and ignites the compressed air fuel mixture, thrusting the piston downward with great force transmitting this power to the drive axle.

 Exhaust Stroke - The piston moves upwards again and the burned exhaust gases are pushed out of the cylinder by way of the open exhaust valves.

Study the video closely and you will see the 4 cycle action and understand how the internal combustion engine works. You will also appreciate the amount of work an engine goes through on a daily basis. A yearly tune up is a good idea to keep your emmissions clean and prevent loss of power and poor gas mileage.

Automotive Technology: Principles, Diagnosis, and Service (3rd Edition)

No comments :