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Unit –I Basics of IC Engines and Fuel-Air & Actual Cycles

Unit –I Basics of IC Engines and Fuel-Air & Actual Cycles

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Unit –I Basics of IC Engines and Fuel-Air & Actual Cycles

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  1. Unit –I Basics of IC Engines and Fuel-Air & Actual Cycles

  2. Syllabus Unit-I :BASICS OF IC ENGINES (5) Heat Engines, IC and EC engines, IC engines construction- components and materials, engine nomenclature, valve diagrams, intake and exhaust systems, engine classification, applications Standard Cycles & Fuel-Air Cycles (5) Fuel-air cycle, assumptions, comparison with air standard cycle, effect of variables on performance, actual engine cycle and various losses

  3. Unit I [10 hrs] • Basics of IC Engines, Fuel Air cycles and actual cycles • Part A] Basics of ICE [5 hrs] • - What is meant by engine and heat engine • Difference between IC & EC engine with examples • Construction: Different components of I. C. Engines and names • of the materials used for different components (Spark plug, engine • block, crank case, intake, exhaust manifold etc) there function, • location. • Nomenclature: (TDC, BDC, Stroke, Swept vol, CC etc.) • Working of 4 stroke I. C. Engine –SI and CI, Difference • between SI & CI engine • - Working of 2 stroke IC Engine (Petrol)

  4. - Difference between two-stroke and four stroke engine. • Classification of I. C. Engines (Inline, radial, V-type, SI & CI, two- • stroke & four stroke etc.) • - Applications of IC Engines • -Theoretical and actual valve timing diagrams. • - Intake and Exhaust Systems (Manifolds and their requirements) • Part B] Fuel air cycle and actual cycle [05 hrs] • Give reference of air standard cycle and start the topic • - What is Fuel air cycle, its assumptions • - Comparison with air standard cycle • Factors affecting fuel air cycle analysis (Composition of • cylinder gases, specific heat variation, dissociation and • molecular change) • Effect of operating variables (CR, AF ratio) on cycle analysis • performance • - Actual cycle and various losses.

  5. Unit I [10 hrs] • Online exam (Compulsory weight age 13 marks): • - Only theoretical treatment. • No numerical would be asked on unit 1 for online exam. • Offline exam (Compulsory weight age 6 marks): • Q 1 a or Q 2a (6 marks). • Only theoretical question for 6 marks for offline exam. • No mathematical treatment. • Total weight age (out of 100 marks): 19 marks.

  6. Lecture No 1 • Learning Objectives: • To learn basics of heat engines, IC and EC engines, IC engines construction- components and materials

  7. Introduction to Engines Difference between IC and EC Engines

  8. Engine Components

  9. Parts of an Engine

  10. Engines Components & Materials • 1. Cylinder block/ Crank case: • For holding major components like crankshaft, • cylinder head, liners, gears, pumps etc. • Cooling jackets, oil passages, passages for push rods etc • Grey CI, Al alloy • 2.Cylinder head: • For fitment of SP/ injectors, valve openings, comb • chamber, valves & valve operating mechanism • CI , Al alloy • 3. Oil pan: • Oil sump • Pressed steel sheet, Al alloy

  11. Engines Components & Materials • 4. Manifolds: • Inlet & exhaust tubing for AF intake & exhaust • CI • 5. Gaskets: • For leak proof sealing between two components • Embossed steel, cork, special rubber

  12. Engines Components & Materials • 7. Piston: • For transmission of force, light weight, high thermal k, • low thermal coeff of expansion • Al alloy • 8. Piston rings: • For high pr leak proof sealing between piston & • cylinder. • Alloy CI with Si, Mn with chromium plating • 9. Connecting rod: • For transmitting force on piston to crankshaft • I-section, drop forged from steel • Axial and bending stresses

  13. Engines Components & Materials • 10. Piston pin/Gudgeon Pin: • For connecting piston to small end of connecting rod • Case hardened steel • 11. Crankshaft: • For converting reciprocketing motion of piston to • rotary motion of crankshaft by connecting rod, • vibration damper and fly wheel fitted • Forged from spheroidal graphite iron • 12. Main & Big end bearings: • For facilitating holding & friction free rotation of • crankshaft • Babbitt material- alloy steel

  14. Engines Components & Materials • 13. Engine Valves: • Inlet –for air/AF intake; Silicon-chrome steel • (C+Ni +Mn+Si) • Exhaust- for exiting burnt gases (C+Ni+Mn+Si+Mb) • 14. Camshaft: • For operating valves (rotates at half speed of C/S) • Forged alloy steel • 15. Silencer/ Mufler: • For reducing exhaust/comb sound • Metal sheet

  15. Parts of an IC Engine Name as many parts as you can CROSS SECTION OF OVERHEAD VALVE FOUR STROKE SI ENGINE

  16. Cylinder head Air cleaner Choke Throttle Intake manifold Exhaust manifold Piston rings Piston Wrist pin Cylinder block Connecting rod Oil gallery to piston Oil gallery to head Crankcase Crankpin Crankshaft Parts of an IC Engine Breather cap Rocker arm Valve spring Valve guide Pushrod Sparkplug If you scored: 25 – 32- Excellent 15 – 24- Good 10 – 14- OK <10- Change your lubricating oil Combustion chamber Tappet Dipstick Cam Camshaft Water jacket Wet liner Connecting rod bearing Main bearing Oil pan or sump

  17. Naming Engine Components Cylinder Block, Cylinder Head, Rocker Arms, Rocker Shaft, Push Rods, Engine Valves, Inlet & Outlet Manifolds, Carburetor, Air Filter, Tappet Cover Piston, Piston Rings, Connecting Rod, Cylinder/ Cylinder Liners, Gudgeon/Piston Pin, Crank Shaft, Big end Bearings, Main/Journal Bearings, Cam Shaft, Cam Followers, Oil Pan, Oil Pump, Oil Filter, Water Pump, Fan Belt, Radiator/HE, Fuel Injector, Fuel Pump, Governor, Spark Plug, Distributor, Ignition Coil, Battery, Dynamo/Alternator, Flywheel, Vibration Damper, Muffler/Silencer, Gaskets, Thermostat, Aux Gears, Super Charger/ Turbo Charger, Fuel Tank Fuel Lines, Fuel Filter, HT & LT Wires/Cables etc

  18. Lecture No 2 • Learning Objectives: • To understand working of 4-stroke SI and CI engines and • 2-stroke SI engines

  19. Spark plug Exhaust valve Inlet valve Cylinder Piston The four-stroke engine

  20. The four-stroke engine Inlet valve opens INDUCTION STROKE

  21. The four-stroke engine Inlet valve open INDUCTION STROKE Piston down

  22. The four-stroke engine Air/Fuel Mixture In Inlet valve open INDUCTION STROKE Piston down

  23. The four-stroke engine Piston up Inlet valve closes COMPRESSION STROKE

  24. Piston up The four-stroke engine Inlet valve closed COMPRESSION STROKE

  25. The four-stroke engine Inlet valve closed BANG POWER STROKE

  26. The four-stroke engine Inlet valve closed Piston down powerfully POWER STROKE

  27. The four-stroke engine Inlet valve closed POWER STROKE Piston down powerfully

  28. The four-stroke engine Inlet valve closed POWER STROKE

  29. The four-stroke engine Exhaust valve open Inlet valve closed EXHAUST STROKE

  30. Piston up The four-stroke engine Exhaust valve open Inlet valve closed Exhaust gases out EXHAUST STROKE

  31. Piston up The four-stroke engine Exhaust valve open Inlet valve closed Exhaust gases out EXHAUST STROKE

  32. The four-stroke engine Exhaust valve closed Inlet valve opens INDUCTION STROKE

  33. And so the cycle continues!!

  34. The four-stroke cycle The four stroke combustion cycle consists of: • 1. Intake • 2. Compression • 3. Combustion • 4. Exhaust

  35. The four-stroke cycle The piston starts at the top, the intake valve opens and the piston moves down to let the engine take in a full cylinder of air and gasoline during the intake stroke The piston then moves up to compress the air/gasoline mixture. This makes the explosion more powerful.

  36. The four-stroke cycle • When the piston reaches the top, the spark plug emits a spark to ignite the gasoline/air mixture. • The gasoline/air mixture explodes driving the piston down. • The piston reaches the bottom of its stroke, the exhaust valve opens and the exhaust leaves out of the tailpipe. • The engine is ready for another cycle.

  37. 4 Processes Cycle Intake Valve Exhaust Valve Exhaust Manifold 4 Intake Manifold 2 1 3 Cylinder Spark Plug Piston Connecting Rod Crank Crankcase Intake Stroke Intake valve opens, admitting fuel and air. Exhaust valve closed for most of stroke Compression Stroke Both valves closed, Fuel/air mixture is compressed by rising piston. Spark ignites mixture near end of stroke. Power Stroke Fuel-air mixture burns, increasing temp and pressure, expansion of combustion gases drives piston down. Both valves closed, exhaust valve opens near end of stroke Exhaust Stroke Exhaust valve open, exhaust products are displaced from cylinder. Intake valve opens near end of stroke.

  38. Working of a 4 Stroke SI Engine

  39. Working of a 2 Stroke SI Engine

  40. Lecture No 3 • Learning Objectives: • To understand engine terminology • To learn about classification of engines • To learn about theoretical and actual valve timings of SI and • CI engines • To learn about engine induction and exhaust systems

  41. Engine Terminology TDC, BDC Stroke/Swept /Displacement Volume (Vs) Clearance Volume (Vc) Compression Ratio CR (r)

  42. Engine Terminology

  43. More Terminology

  44. Terminology • Bore = d • Stroke = s • Displacement volume =Vs = • Clearance volume = Vc • Compression ratio = r r = Vs + Vc Vc

  45. Classification of IC Engines • Based on No of stroke per cycle: • Four stroke • Two stroke • Based on thermodynamic cycle: • Otto/Constant volume cycle • Diesel/Constant pressure cycle • Dual Cycle • Based on No of cylinders: • Single cylinder • Multi-cylinders

  46. Classification of IC Engines • Based on arrangement of cylinders: • Inline engines • V – engines • Radial engines • Opposed cylinders engines • Opposed pistons engines • Based on ignition systems: • SI engines • CI engines • Based on cooling system: • Air cooled • Liquid cooled

  47. 4. - Cylinder Orientation There is no limit on the number of cylinders that a small engines can have, but it is usually 1 or 2. Vertical Slanted Horizontal Multi position

  48. 4. - Cylinder Orientation—cont. Three common cylinder configuration in multiple cylinder engines: V Horizontally opposed In-line