Engine Overview

Definition

• An engine is a machine designed to convert energy into mechanical energy.
• Heat engines burn fuel to create heat used to do work.

Types of Engines

• Internal Combustion Engine: Burns fuel inside the engine cylinder.
• External Combustion Engine: Burns fuel outside the cylinder.

Importance

• The engine is considered the heart of the automobile industry.

Main Parts of an Internal Combustion Engine

1. Cylinder Block

   • Basic framework of the engine.
   • Composed of three parts:
     • Cylinder for piston movement.
     • Ports/openings for valves.
     • Passages for cooling water.
   • Typically made of gray cast iron or aluminum.
   • Houses lubrication oil through drilled passages (oil galleries).

2. Cylinder Head

   • Connects to the cylinder block, made from cast iron or aluminum alloy.
   • Contains combustion chamber, valve guides, valve seats, and threaded holes for spark plugs.
   • Types:
     • Loop flow type.
     • Offset cross flow type.
     • Inline cross flow type.

3. Crankcase

   • Includes the oil pan and lower part of the cylinder block.
   • Supports the crankshaft's main journals and bearing.

4. Oil Pan

   • Reservoir for engine lubricating oil.
   • Usually made of pressed steel or aluminum alloy.
   • Contains a drain plug for oil replacement.

5. Manifolds

   • Pipes attached to the cylinder head carrying air-fuel mixture and exhaust gases.
   • Made of cast iron.

6. Gaskets

   • Provide leak-proof joints between surfaces.
   • Made from materials like cork, rubber, and asbestos.

7. Cylinder Liners

   • Prevent cylinder wear and can be replaced.
   • Types:
     • Dry liners: Machined accurately.
     • Wet liners: In contact with cooling water.

8. Pistons

   • Convert pressure energy from fuel combustion into mechanical power.
   • Moves up and down in the cylinder, transferring power to the crankshaft.
   • Has three to five piston rings for sealing.
   • Made of cast iron or aluminum alloy.

9. Piston Rings

   • Fitted into piston grooves to maintain a seal.
   • Types:
     • Compression rings.
     • Oil control rings.

10. Connecting Rod

    • Converts reciprocating motion of the piston into rotary motion of the crankshaft.
    • Made of alloy steel or duralumin, with an I-beam cross-section.

11. Piston Pin

    • Connects the piston to the connecting rod.
    • Made from case-hardened steel.
    • Types:
      • Set screw type.
      • Semi-floating.
      • Fully floating.

12. Crankshaft

    • Converts reciprocating motion of the piston into rotating motion.
    • Made of heat-treated alloy steel, machined for precision.

13. Camshaft

    • Drives the opening of valves, converting rotary motion into linear motion.
    • Made from forged alloy steel, with various drive mechanisms (gear, chain, belt).

14. Flywheel

    • Attached to the crankshaft, maintains constant speed of the engine.

15. Engine Valves

    • Control entry of air-fuel mixture and exit of combustion products.
    • Located at inlet and outlet openings of the engine cylinder.

Conclusion

• Understanding the construction and function of each engine part is crucial for the study of automobile engines.
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