With a suitable sketch explain the different parts of an I.C Engine
5. A] With a suitable sketch explain the different parts of an I.C Engine
Answer:
Parts of I.C Engine:
1. Cylinder: It is the main body and heart of the engine in which fuel is burnt and piston reciprocates to develop the power. It is in direct contact with the products of combustion and it must be cooled to avoid damage.
2. Piston: It is a gas-tight movable cylindrical component fitted perfectly inside the cylinder. The piston is used to compress the fuel during compression stroke. It transmits the force exerted by the combustion of fuel to the connecting rod and finally to the crankshaft. Piston is usually made up of cast iron (or) aluminium alloy.
3. Cylinder head: One end of the cylinder is closed by means of a removable plate known as cylinder head. Cylinder head usually contains the inlet valve for admitting the mixture of air and fuel and exhaust valve for discharging the products of combustion.
4. Piston rings: Piston rings are metallic rings and are fitted in the circumferential grooves provided at the top end outer surface of the piston. It gives gas tight sealing between the piston and cylinder while the piston reciprocating inside the cylinder. Piston rings maintain compression pressure inside the cylinder and prevent leakage of high-pressure gases into the crank case.
5. Connecting rod: It is a kinematic link that connects the piston and the crank. It converts reciprocating motion of piston into rotary motion of crank. Its small end is connected to the piston with the help of piston pin and big end to the crank-by-crankpin. It transmits the force from piston to crank.
6. Crank and Crankshaft: The crank is a rotating element with one of its ends connected to the lower end of the connecting rod while the other is connected to the shaft called crankshaft. It rotates about the axis of the crankshaft and causes the connecting rod to oscillate. The crankshaft is supported in the main bearings and has a flywheel mounted on it to reduce the fluctuation of speed. The main function of crankshaft is to transmit the power developed by the engine to useful work (to run vehicle, boat, ship etc.)
7. Crankcase: It is the lower part of the engine serving as an enclosure for the crankshaft and also acts as an oil sump for lubricating oil.
8. Valves: Two types of valves i.e., inlet and exhaust valves located on the cylinder head (or)on the side of the cylinder.
- (1) Inlet valve: It is provided on the cylinder head for regulating the charge coming into the cylinder.
- (2) Exhaust valve: It is provided on the cylinder head for removing exhaust gases (products of combustion) from the cylinder.
9. Flywheel: It is a wheel mounted on the crankshaft which stores excess energy during the power stroke and releases (or) returns that energy during the other three idle strokes, thus maintaining the uniform rotation of the crankshaft.
10. CAM: Cam is a rotating element used to control the opening and closing of valves. Cams are designed in such a way that to open the valve at the correct timing and to keep them open for the required duration and to close them at the correct time.
11. Spark plug / Fuel injector: In case of petrol engines, the spark plug provides the spark at the end of compression stroke to initiate the combustion process. In case of diesel engines, spark plug is replaced by fuel injector which injects diesel into the compressed air to initiate the combustion process.