Topic:Internal combustion engines
From Wikiversity
Internal Combustion Engines or IC Engines as they are popularly known as, is used in everyday life and almost everywhere such as in cars and bikes. Study of Engines has evolved into a branch of Mechanical Engineering.
There are two types of IC Engines,
- Four Stroke Engine, and
- Two Stroke Engine
Also the engines can also be classified on what cycles they follow, given below
- Diesel Engine
- Gasoline Engine
Four stroke engines, as the name suggests, have totally four different cycles, namely
a. intake
b. compression
c. ignition/expansion
d. exhaust
In the two stroke, there are just two cycles and each of them having two cycles running concurrently.
a. intake/exhaust
b. ignition/compression
A few definitions:
TDC: Top Dead Centre. This is the top most part the piston can reach in a vertical engine.
BDC: Bottom Dead Centre. This is the bottom most part the piston can reach in an vertical engine.
Petrol Engine
Petrol Engines, also known as Spark Ignition engines, needs ignition from an external source for the engine to start. Also, as the name suggests, this engine uses spark plug for providing a spark and the fuel used is petrol(gasoline). Let us see how the engine works.
During the Inlet stroke, the inlet valve opens and the engine gets air and fuel in a particular air-fuel ratio, typically in the order of 15:1 to 20:1. As the piston starts to move to the TDC, the whole mixture starts to compress. After the compression, the expansion stroke occurs where the spark plug lets in a spark and the whole mixture burns. This is also known as the power stroke as this stroke provides power to the crank. Now the piston reaches the BDC. After the expansion stroke, the piston starts moving up and starts moving up to the TDC.
I request the other mechanical engineers to carry on. I will edit when I get time.
