Practical 1 Engine components.pptx
- 1. Practical No. 1 Study of Components of I.C. Engine 1
- 2. INTRODUCTION • Heat engine is a machine for converting heat, developed by burning fuel into useful work (OR) It is an equipment which generates thermal energy and transforms it into mechanical energy. Heat engine is of two types (based on combustion of fuel) (i) External combustion engine, and (ii) Internal combustion engine.
- 3. External combustion engine: • It is the engine designed to derive its power from the fuel, burnt outside the engine cylinder. • Here combustion process uses heat in the form of steam, which is generated in a boiler, placed entirely separate from the working cylinder .
- 4. Internal combustion engine (I. C. Engine): • It is the engine designed to derive its power from the fuel, burnt within the engine cylinder. • Here combustion of fuel and generation of heat takes place within the cylinder of the engine.
- 7. Engine components: Cylinder: • It is a part of the engine which confines the expanding gases and forms the combustion space. • It is the basic part of the engine. It provides space in which piston operates to suck the air or air-fuel mixture. • The piston compresses the charge and the gas is allowed to expand in the cylinder, transmitting power for useful work. • Cylinders are usually made of high grade cast iron.
- 8. Cylinder circular cylinders in the engine block, inside which the piston reciprocate, and beneath which crank is fixed, thus confining the motion linkage Cylinder Cylinder block • Cylinder block: It is the solid casting which includes the cylinder and water jackets (cooling fins in the air cooled engines).
- 9. Cylinder Block for Multi-cylinder Engines
- 10. Cylinder block for motorcycle
- 11. • Cylinder head: It is detachable portion of an engine which covers the cylinder and includes the combustion chamber, spark plugs and valves.
- 12. Cylinder head:
- 13. Cylinder Head for motorcycle
- 14. Cylinder Head and block
- 16. Cylinder liner or sleeve
- 17. Piston: • It is a cylindrical part closed at one end which maintains a close sliding fit in the engine cylinder. • It is connected to the connecting rod by a piston pin. • The force of the expanding gases against the closed end of the piston, forces the piston down in the cylinder. • This causes the connecting rod to rotate the crankshaft. • Cast iron is chosen due to its high compressive strength, low coefficient of expansion, resistance to high temperature, ease of casting and low cost. • Aluminum and its alloys are preferred mainly due to its lightness.
- 21. Piston ring: It is a split expansion ring, placed in the groove of the piston. Piston rings are fitted in the grooves, made in the piston. They are usually made of cast iron or pressed steel alloy.
- 24. The functions of the ring are as follows: (a) It forms a gas tight combustion chamber for all positions of piston. (b) It reduces contact area between cylinder wall and piston wall for preventing friction losses and excessive wear. (c) It controls the cylinder lubrication. (d) It transmits the heat away from the piston to the cylinder walls. Piston rings are of two types: (a) Compression ring and (b) Oil ring. (a) Compression rings are usually plain, single piece and are always placed in the grooves, nearest to the piston head.
- 25. (b) Oil ring: • Oil rings are grooved or slotted and are located either in lowest groove above the piston pin or in a groove above the piston skirt. • They control the distribution of lubrication oil in the cylinder and the piston. • They prevent excessive oil consumption also. • Oil ring is provided with small holes through which excess oil returns back to the crankcase chamber.
- 26. Piston pin: • It is also called wrist pin or gudgeon pin. • Piston pin is used to join the connecting rod to the piston. • It provides a flexible or hinge like connection between the piston and the connecting rod. • It is usually made of case hardened alloy steel.
- 27. Connecting rod: • It is a special type of rod, one end of which is attached to the piston and the other end to the crankshaft. • It transmits the power of combustion to the crankshaft and makes it rotate continuously. • It is usually made of drop forged steel.
- 28. 28 Connecting Rod • Connects the piston and piston pin to the crankshaft.
- 29. Crankshaft: • It is the main shaft of an engine which converts the reciprocating motion of the piston into rotary motion of the flywheel. • Usually the crankshaft is made of drop forged steel or cast steel. • The space that supports the crankshaft in the cylinder block is called main journal, whereas the part to which connecting rod is attached is known as crank journal.
- 31. 31 Crankshaft • Along the the piston pin and connecting rod it converts the up and down motion (reciprocating) of the engine to spinning (rotary) motion.
- 32. Fly wheel: • Fly wheel is made of cast iron. Its main functions are as follows: (a) It stores energy during power stroke and returns back the same energy during the idle strokes, providing a uniform rotary motion by virtue of its inertia. (b) It also carries ring gear that meshes with the pinion of the starting motor. (c) The rear surface of the flywheel serves as one of the pressure surfaces for the clutch plate. (d) Engine timing marks are usually stamped on the flywheel, which helps in adjusting the timing of the engine. (e) Some times the flywheel serves the purpose of a pulley for transmitting power.
- 34. Crankcase: • The crankcase is that part of the engine which supports and encloses the crankshaft and camshaft. • It provides a reservoir for the lubricating oil of the engine.
- 36. 36 Camshaft • Through the use of an eccentric the cam lobes push the valves open. • The valve springs close them.
- 37. Cam shaft: • It is a shaft which raises and lowers the inlet and exhaust valves at proper time. • Camshaft is driven by crankshaft by means of gears, chains or sprockets. • The speed of the camshaft is exactly half the speed of the crankshaft in four stroke engine. • Camshaft operates the ignition timing mechanism, lubricating oil pump and fuel pump. • It is mounted in the crankcase, parallel to the crankshaft.
- 38. 38 Timing Gears • These gears drive the camshaft from the crankshaft.
- 39. Timing gear: • Timing gear is a combination of gears, one gear of which is mounted at one end of the camshaft and other gear on the end of the crankshaft. • Camshaft gear is bigger in size than that of the crankshaft gear and it has twice as many teeth as that of the losing crankshaft gear. • For this reason, this gear is commonly called Half time gear. • Timing gear controls the timing of ignition, timing of opening and closing of valves as well as fuel injection timing.
- 40. Inlet manifold: • It is that part of the engine through which air or air-fuel mixture enters into the engine cylinder. • It is fitted by the side of the cylinder head. Exhaust manifold: • It is that part of the engine through which exhaust gases go out of the engine cylinder. • It is capable of with-standing high temperature of burnt gases. • It is fitted by the side of the cylinder head.
- 41. Top dead centre - When the piston is at the top of its stroke, it is said to be at the top dead centre (TDC), Bottom dead centre - when the piston is at the bottom of its stroke, it is said to be at its bottom dead centre (BDC). Scavenging The process of removal of burnt or exhaust gases from the engine cylinder is known as scavenging. Entire burnt gases do not go out in normal stroke, hence some type of blower or compressor is used to remove the exhaust gases in two stroke cycle engine.
- 42. Engine parts Materials used 1. Cylinder head Cast iron, Cast Aluminum 2. Cylinder liner Cast iron, Cast steel 3. Engine block Cast iron, Cast Aluminum 4. Piston Cast iron, Aluminum alloy 5. Piston pin Forged steel, Aluminum alloy 6. Piston ring Forged steel alloy, Cast Aluminum 7. Connecting rod Forged steel, Aluminum alloy 8. Main bearing White metal 9. Connecting rod bearing Bronze 10. Crank shaft Cast steel, forged steel 11. Cam shaft Forged steel, cast iron 12. Timing gear Cast iron 13. Manifolds Cast iron 14. Fly wheel Cast iron 15. Gasket Cork, copper, asbestos 16. Crankcase Cast iron, Cast Aluminum Materials of construction of engine parts