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IC Engines- 2 stroke and 4 stroke

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IC Engines- 2 stroke and 4 stroke

  2. 2. Introduction :Introduction :  = • Heat engine : It can be defined as any engine that converts thermal energy to mechanical work output. Examples of heat engines include: steam engine, diesel engine, and gasoline (petrol) engine. • On the basis of how thermal energy is being delivered to working fluid of the heat engine, heat engine can be classified as an internal combustion engine and external combustion engine.
  3. 3. Types of EngineTypes of Engine Internal Engine Petrol Engine Diesel Engine External Engine Steam Engine Turbines
  4. 4. External CombustionExternal Combustion EngineEngine• In an External combustion engine, combustion takes place inside the cylinder. • -Steam engine is an example of external combustion engine, where the working fluid is steam.
  5. 5. IC EnginesIC Engines • In an Internal combustion engine, combustion takes place within the cylinder. • Petrol engine is an example of internal combustion engine, where the working fluid is a mixture of air and fuel .
  6. 6. Internal combustion engines may be classified as :Internal combustion engines may be classified as : – Spark Ignition engines.Spark Ignition engines. – Compression Ignition engines.Compression Ignition engines. • Spark ignition engine (SI engine):Spark ignition engine (SI engine): An engine in whichAn engine in which the combustion process in each cycle is started by usethe combustion process in each cycle is started by use of an external spark.of an external spark. • Compression ignition engine (CI engine):Compression ignition engine (CI engine): An engine inAn engine in which the combustion process starts when the air-fuelwhich the combustion process starts when the air-fuel mixture self ignites due to high temperature in themixture self ignites due to high temperature in the combustion chamber caused by high compression.combustion chamber caused by high compression. – Spark ignition and Compression Ignition engineSpark ignition and Compression Ignition engine operate on either a four stroke cycle or a twooperate on either a four stroke cycle or a two stroke cycle.stroke cycle.
  7. 7. • Four stroke cycleFour stroke cycle : It has four piston strokes: It has four piston strokes over two revolutions for each cycle.over two revolutions for each cycle. • Two stroke cycleTwo stroke cycle : It has two piston strokes: It has two piston strokes over one revolution for each cycle.over one revolution for each cycle. SI Engine & CI Engine have two types:-
  8. 8. Figure2: Engine components Engine components :-
  9. 9. Internal combustion EngineInternal combustion Engine ComponentsComponents:-:- 1. Block : Body of the engine containing cylinders, made of cast iron or aluminium.
  10. 10. 2. Cylinder2. Cylinder C A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels.
  11. 11. 3. Head3. Head :: The pieceThe piece which closes the endwhich closes the end of the cylinders,of the cylinders, usually containingusually containing part of the clearancepart of the clearance volume of thevolume of the combustioncombustion chamber.chamber.
  12. 12. 4. Connecting Rod4. Connecting Rod  In a reciprocating piston engine , the connecting rod or conrod connects the piston to the crank or crankshaft.
  13. 13. 5. Piston5. Piston Piston The piston of an internal combustion engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder.
  14. 14. 6. Piston rings6. Piston rings A piston ring is a metal rings that fit into circumferential grooves around the piston and form a sliding surface against the cylinder walls.
  15. 15. 7. Crankshaftt:: Rotating shaftRotating shaft through whichthrough which engine workengine work output isoutput is supplied tosupplied to externalexternal systemssystems..
  16. 16. 8. Camshaft8. Camshaft :: Rotating shaft usedRotating shaft used to push open valvesto push open valves at the proper time inat the proper time in the engine cycle,the engine cycle, either directly oreither directly or through mechanicalthrough mechanical or hydraulic linkageor hydraulic linkage (push rods, rocker(push rods, rocker arms, tappets) .arms, tappets) .
  17. 17. 9. Intake manifold9. Intake manifold:: Piping system whichPiping system which deliver incoming air todeliver incoming air to the cylinders, usuallythe cylinders, usually made of cast metal,made of cast metal, plastic, or compositeplastic, or composite material . In most SImaterial . In most SI engines, fuel is addedengines, fuel is added to the air in the intaketo the air in the intake manifold system eithermanifold system either by fuel injectors orby fuel injectors or with a carburetor.with a carburetor.
  18. 18. 10. Exhaust10. Exhaust manifoldmanifold :: PipingPiping system whichsystem which carries exhaustcarries exhaust gases away fromgases away from the enginethe engine cylinders, usuallycylinders, usually made of cast ironmade of cast iron
  19. 19. 11. Spark plug11. Spark plug :: Electrical deviceElectrical device used to initiateused to initiate combustion in ancombustion in an SI engine bySI engine by creating highcreating high voltage dischargevoltage discharge across anacross an electrode gapelectrode gap
  20. 20. 12. Flywheel12. Flywheel :: Rotating massRotating mass with a largewith a large moment of inertiamoment of inertia connected to theconnected to the crank shaft of thecrank shaft of the engine.engine. The purpose ofThe purpose of the flywheel is tothe flywheel is to store energystore energy ..
  21. 21. 13. Fuel13. Fuel injectorinjector :: AA pressurizedpressurized nozzle that spraysnozzle that sprays fuel into thefuel into the incoming air (SIincoming air (SI engines )or intoengines )or into the cylinder (CIthe cylinder (CI engines).engines).
  22. 22. 14. Combustion chamber14. Combustion chamber:: The endThe end of the cylinder between the head and theof the cylinder between the head and the piston face where combustion occurs .piston face where combustion occurs . The size of combustion chamberThe size of combustion chamber continuously changes from minimumcontinuously changes from minimum volume when the piston is at TDC to avolume when the piston is at TDC to a maximum volume when the piston atmaximum volume when the piston at
  23. 23. Four Stock SI Engine & CIFour Stock SI Engine & CI EngineEngine :-:- 1. SI Engine:- It this engine, cycle of operation is completed in four stocks of the piston or two strokes of crankshaft . Each stroke consists of 180 degree of crankshaft rotation. Four strokes are follows:- A) Suction stroke. B) Compression stroke. C) Expansion stroke. D) Exhaust stroke.
  24. 24. 1. Suction stroke:-1. Suction stroke:- In suction stroke fuel-In suction stroke fuel- air mixture enters in the cylindair mixture enters in the cylinderer
  25. 25. 2. Compression Stroke:-2. Compression Stroke:- compression ratio of petrol engine is 6-10compression ratio of petrol engine is 6-10
  26. 26. 3. Power or Expansion3. Power or Expansion strokestroke:-:-
  27. 27. Exhaust stroke:-Exhaust stroke:-
  28. 28. 2. CI Engine:-2. CI Engine:- The diesel engine was first patented in 1892 by Rudolph Diesel. Like SI Engine, CI Engine complete cycle in 4 stroke. Four stokes are:- 1. intake or suction stroke:-The intake valve opens, and fresh air (containing no fuel), is drawn into the cylinder.
  29. 29. 2. Compression stroke:-2. Compression stroke:- •Both valves stay closed •Piston moves from BDC to TDC, compressing air to 22:1 increases the temperature inside the cylinder to above 1000 •Compressing the air to this extent
  30. 30. 3. Power stroke:-3. Power stroke:- •When the piston is at the end of compression stroke(TDC) the injector sprays a mist of diesel fuel into the cylinder. •Both valves stay closed •When hot air mixes with diesel fuel an explosion takes place in the cylinder. •Expanding gases push the piston from TDC to BDC
  31. 31. 4. Exhaust Stroke4. Exhaust Stroke •Piston moves from BDC to TDC •Exhaust valve opens and the exhaust gases escape •Intake valve remains closed
  32. 32. 2- Stroke Engine2- Stroke Engine As the name itself implies, all the processes in the two stroke cycle engine are completed in two strokes. In the two stroke engine there is a two opening called ports are provided in place of valve of four stroke engines. One port known as a inlet port and another port is known as a exhaust port.
  33. 33. Working of the two strokeWorking of the two stroke petrol enginepetrol engine •At the beginning of the first stroke piston Is at the TDC. Piston moves from TDC to BDC First stroke:- •Another A/F/O mixture is sucked into crankcase while First one is compressed in cylinder Intake/ compression StrokeIntake/ compression Stroke
  34. 34. Fig. B Piston uncovers transfer port During first stroke Fig. A Beginning of the first stroke
  35. 35. Second strokeSecond stroke :-:- Power/ExhaustPower/Exhaust StrokeStroke •In this stroke piston moves from BDC to TDC. •Exhaust port is uncovered and exhaust starts leaving.
  36. 36. Fig. C. Transfer port covered Fig. D. Compression commenced
  37. 37. •Because it is light, can be used at anyBecause it is light, can be used at any angle, operates at high RPM Weed eatersangle, operates at high RPM Weed eaters Chain sawsChain saws BoatsBoats SnowmobilesSnowmobiles Dirt bikesDirt bikes Good uses of two strokeGood uses of two stroke enginesengines
  38. 38. 11/2001 40 Usually don’t use 2 strokesUsually don’t use 2 strokes in :-in :- Because of pollution, efficiency, lack of low RPM power, and convenience of not mixing oil – Cars – Trucks – Road bikes – Lawn mowers – Generators
  39. 39. Difference between 4Difference between 4 stroke & 2 strokestroke & 2 stroke Principle 4 stroke 2 stroke 1.Stroke per cycle 2.Crank rotation per cycle 3.Power stroke per cycle 4.Power 5.Fly wheel 6.Sizeof engine 7.Admission of charge 8.Valves 9.Crankcase 10.Direction of rotation the crankshaft 11.Lubricant oil consumption 12.Thermal efficiency 13.Mechanical efficiency 14.uses Four piston stroke Two crank rotation Half of speed of crankshaft In every alternate revolution Heavy flywheel Heavier , larger and more space Directly into cylinder Inlet and exhaust valves It is not hermetically sealed In one direction Less Higher Low Cars, tractors, buses Only two piston stroke Only one crank rotation Equal to speed of crankshaft In every revolution Lighter flywheel Lighter , more compact and less space First admitted into crankcase, then transfer to engine In place of valves, ports are there Hermetically sealed In both directions More Less High Mopeds, scooter, motor, cycle
  40. 40. Gasoline vs. Diesel EngineGasoline vs. Diesel Engine
  41. 41. Wartsila-Sulzer RTA96-C is the largest IC engine, but the Space Shuttle Solid Rocket Boosters are the most powerful (≈ 42 million horsepower (32 hp/lb); not shaft power but kinetic energy of exhaust stream) Most powerful shaft-power engine: Siemens SGT5-8000H stationary gas turbine (340 MW = 456,000 HP) (0.52 hp/lb) used for electrical power generation Most powerful internalMost powerful internal combustion enginecombustion engine
  42. 42. Safety PrecautionsSafety Precautions Noise Fuel Flammability Maintenance Water Issues
  43. 43. • • • • • • ml • • ReferencesReferences::