There are two main types of internal combustion (IC) engines: the spark ignition (SI), also called the petrol engine, and compression ignition (CI), also called the diesel engine. Most of the components of both the engines are the same, but their fuel burning process differs. In SI engines the burning of fuel occurs by the spark generated by the spark plug while in CI engines the burning of fuel occurs by its compression to high pressures.
Here are the important components of the IC engines:
1) Cylinder block: The cylinder block is the main body of the engine, the structure that supports all the other components of the engine. In the case of the single cylinder engine the cylinder block houses the cylinder, while in the case of multi-cylinder engine the number of cylinders are cast together to form the cylinder block. The cylinder head is mounted at the top of the cylinder block.
When the vehicle runs, large amounts of heat are generated within the cylinder block. To remove this heat the cylinder block and the cylinder head are cooled by water flowing through the water jackets within larger engines such as those found in cars and trucks. For smaller vehicles like motorcycles, fins are provided on the cylinder block and on the cylinder head to cool them. The bottom portion of the cylinder block is called a crankcase. Within the crankcase is where lubricating oil, which is used for lubricating various moving parts of the engine, is stored.
2) Cylinder: As the name suggests it is a cylindrical shaped vessel fitted in the cylinder block. This cylinder can be removed from the cylinder block and machined whenever required to. It is also called a liner or sleeve. Inside the cylinder the piston moves up and down, which is called the reciprocating motion of the piston. Burning of fuel occurs at the top of the cylinder, due to which the reciprocating motion of the piston is produced. The surface of the cylinder is finished to a high finish, so that there is minimal friction between the piston and the cylinder.
In smaller vehicles like motorcycles there is only a single cylinder. In larger vehicles like high cc motorcycles, cars, trucks, etc., there are more than one cylinder in the engine. These engines are called multi-cylinder engines. The number of cylinders in these engines can be 2, 3,4, 6. In very large engines such as those of ships, the number of cylinders can be 12. The displacement volume of the engine depends on the size of the cylinder.
3) Piston: The piston is the round cylindrical component that performs a reciprocating motion inside the cylinder. While the cylinder itself is the female part, the piston is the male part. The piston fits perfectly inside the cylinder. Piston rings are fitted over the piston. The gap between the piston and the cylinder is filled by the piston rings and lubricating oil. The piston is usually made up of aluminum.
When the fuel inside the cylinder is burnt the produced heat energy causes the reciprocating motion of the piston. This is the first mechanical motion produced from thermal energy. The rest of the components convert the reciprocating motion of the piston into a rotary motion which is transmitted to the wheels of the vehicle you are driving.Components of an Internal Combustion (IC) Engine - Part 2