Components of IC engine and their functions

1. Cylinder:

• Heart of the engine where burning takes place and power is developed.
• Provides space for piston to suck the air or air-fuel mixture.
• Made up of high-grade cast iron.
• Inside diameter is called cylinder bore.

2. Cylinder block:

• Encloses cylinder, piston, crankshaft, water jacket, etc.

3. Cylinder head:

• Detachable cast piece bolted to the top of the cylinder block.
• Encloses the cylinder from the top to form combustion chamber.
• Includes valve ports, intake and exhaust manifolds, valve and valve operating system.

4. Cylinder liner or sleeve:

• Fits inside the cylinder bore and forms the inner wall of the cylinder.
• Piston reciprocates in closed contact of liner.
• Classified as:

1. a) Dry liner: cooling water doesn’t come in direct contact between the dry liner and cylinder.
2. b) Wet liner: Comes in contact with cooling water.

5. Piston:

• Cylindrical part closed at one end which maintains a close sliding fit in the engine cylinder.
• Connected to connecting rod by a piston pin.
• The Force of expanding gases against the closed end of piston, forces the piston down in the cylinder.
• Upper two grooves are for compression rings (Without oil vent).
• Lower two grooves are for oil circulation (with oil vent).

6. Piston head and skirt:

• The top of the piston is called piston head or crown and skirt is that portion of the piston below the piston pin which is designed to absorb the side movements of the piston.

7. Piston rings:

• Split expansion ring, placed in the groove of piston.
• Performs three functions:

1. a) Seals the gas pressure above the piston.
2. b) Reduces contact area between the cylinder wall and piston wall preventing friction losses and excessive wear.
3. c) Controls the cylinder wall lubrication.

8. Piston pin:

• Used to join the connecting rod to the piston.
• Also called wrist/gudgeon pin.

9. Connecting rod:

• Used to connect crankshaft at one end and piston on the other end through piston pin.
• Transmits power of combustion to the crankshaft and makes it rotate continuously.

10. Crankshaft:

• Converts the reciprocating motion of the piston into the rotary motion of the flywheel.
• Takes the downward thrust of the piston during power stroke.
• One end of crankshaft carries gears or sprocket that drive camshaft, lubricating oil pump and fuel pump.
• Another end is connected to a fly wheel and power transmission system.

11. Flywheel:

• Is a Heavy metallic disc attached to one end of the crankshaft.
• Stores energy during power stroke and releases it during other idle strokes.
• Sometimes serves the purpose of a pulley for transmitting power.

12. Crank case:

• It supports and encloses the crankshaft and camshaft.
• Provides a reservoir for the lubricating oil of the engine.
• Also serves as mounting unit for oil pump, oil filter, generator, starting motor and ignition components.

13. Camshaft:

• Raises and lowers the inlet and exhaust valves at a proper time.
• Driven by crankshaft through gears or chains and sprockets.
• Actuates the valve mechanism.

14. Cam:

• Tapered profile machined on the camshaft to give required motion for valve operation.

15. Valves:

• Used for opening and closing of the passage leading to the engine cylinder.
• Inlet valve allows air or air-fuel mixture into the combustion chamber.
• Exhaust valve allows burnt gases to go out of the engine cylinder.

16. Timing gear:

• Controls the timing of ignition, timing of opening and closing of valves as well as fuel injection timing.

17. Rocker arm:

• Used to change upward motion of push rod to downward motion for opening an engine valve.
• Connected to push rod at one end and operates valve by its other end fitted with valve stem and spring on the valve head.