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Internal Combustion Engine

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Er. Uttam Raj Timilsina(MSc.Engineering,IIT Roorkee)
Professor of Agricultural Engineering,Agriculture and Forestry University (AFU), Rampur, Chitwan, Nepal
uttamrajtimilsina@gmail.com
*All Right Reserved**
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Internal Combustion Engine

  1. 1. AEN-301,Farm Power and Machinery • Internal Combustion Engine(Two Lectures)  Eengine types  Components of IC engines and their functions  Principles of operation of two stroke and four stroke cycle Diesel andpetrol engines  Systems in two wheel and fou  cleaining, cooling and lubrication systems Prepared by Er. Uttam Raj Timilsina(MSc.Engineering,IIT Roorkee) Professor of Agricultural Engineering,,AFU
  2. 2. Engines • External Combustion Engine: It is the engine in which the fuel is burned outside the cylinder to boil water and generate steam which was fed into the top and bottom of cylinder through sliding valves for the downward and then upward movement of piston to rotate the crankshaft.  Examples of EC Engines are - steam traction engines,railroad locomotives,steam automobiles etc. • Internal Combustion Engine: It is the engine in which the fuel is burned and the power is generated within a closed cylinder.All common oil burning engines are the examples.
  3. 3. History of IC engines(1892-1901)
  4. 4. Internal Combustion Engines
  5. 5. Internal Combustion Engines Classification of IC Engines 1. Stationary or Automotivetypes. 2. Single or multiple cylinder types 3. Slow,Medium or High speed types: Slow speed: below 350 rpm, Medium speed:350-1000 rpm, High speed: Greater than 1000 rpm 4. Horizontal or vertical types 5. Two or four stroke cycle types 6. Spark ignition or compression ignition types or Carburettor type(Petrol engine) or Diesel engine 7.
  6. 6. Components or parts of IC engines • Cylinder Head • Cylinder liner • Engine Block • Piston with piston Rings and piston Pin • Connecting Rod • Bearings • Crankcase • Crankshaft,Camshaft,Timing gears, • Engine Valves with valves springs,push rod • Fly wheel • Gaskets,etc
  7. 7. Component of IC Engines and their functions
  8. 8. Two stroke single cylinder Diesel engine
  9. 9. Four stroke single cylinder petrol Engine
  10. 10. Multi cylinder diesel Engine
  11. 11. Principle of operation of four stroke cycle engine • Intake stroke: Downward movement of piston.Suction of air in case of diesel engine takes place and suction of air plus fuel mixed from carburettor takes place in case of petrol engine • Compression stroke:Upward movement of piston.compression takes place under a high pressure of 105 kg per square cm or above • Power stroke: Downward movement of piston.Burning or explosion of fuel takes place pussing down the piston • Exhaust stroke: Upward movement of piston with Exahaustion of burned air out from combustion chamber
  12. 12. Four stroke petrol engine
  13. 13. Four stroke petrol engine
  14. 14. Multi cylinder four stroke Engines
  15. 15. Two stroke cycle Engine,principle of operation
  16. 16. Live action of multicylinder petrol engine
  17. 17. Engine Terminology • Stroke-Bore-Ratio: It is expressed as L/D ratio where L=length of the piston stroke(mm) D=Diameter of the Cylinder(mm) This ratio for Tractor Engine is about 1.25 and it varies between 1.00-1.45 • Compression Ratio: Compression Ratio of an engine is expressed as the total cylinder volume at BDC divided by the clearance volume or compressed volume at TDC r=vt/vc,where r=compression ratio, vt=total cylinder volume(c.c),vc=clearance volume(c.c) In petrol engine it ranges between 4:1 and 8:1 whereas compression ratio of diesel engines are in the order of 14:1 and 20:1.Efficiency increase with higher compression ratio in petrol engine.
  18. 18. • Piston Displacement: It is the volume displaced by the piston during one stroke usually expressed in cubic centimeter and also known as Swept volume and can be computed as Pd=A*L,where Pd=piston volume(cubic.cm),A=piston area(sq.cm),L=length of the piston travel or piston stroke(cm)
  19. 19. Engine Terminology contd… • Displacement volume:The displacement volume of an engine is the total swept volume of all the pistons during power stroke occuring in a period of one minute.It may be expressed as: Vd=A*L*n Where, Vd=Displacement volume,c.c/min A=piston area(sq.cm) L=piston stroke(cm) n=Number of power stroke /min of the all cylinders • Piston Speed :The piston speed of an engine is the total travel of the piston in a cylinder during a period of one minute and expressed as: Sp=2LN,where,Sp=piston speed,(metre/minute) L=Piston stroke(metre),N=Engine rpm Piston speed of the high speed Tractor Engine ranges between 300-500 metres/min • Horse Power:It is the rate of doing work equivalent to 75 kg metre/sce
  20. 20. Contd… • Engine Cycle: A cycle consist of the events taking place in each cylinder of an engine between two successive explosions or two power strokes in that cylinder • Indicated Mean Effective Pressure(IMEP): It is an average net pressure in kg/sq.cm on the piston during the power stroke only • Indicated Horse Power(IHP): It is the total horse power developed by all cylinders and received by pistons disregarding friction and losses within the engine.It can be calculated as IHP=P*L*A*n/75*60 where,P=indicated mean effective pressure(kg/sq.cm) L=Piston stroke(cm),A=piston area(sq.cm),n=Total number of power stroke/min for all cylinders
  21. 21. Terminology contd… • Brake Horse Power: It is the horse power available at the crankshaft and measured by a suitable dynamometer. • Mechanical Efficiency: It is the ratio of the brake horse power to the indicated horse power and is expressed as: Mechanical Efficiency=BHP/IHP*100 • Specific Fuel Consumption: It is the quantity of fuel consumed by an oil engine on the basis of per hp- hour.It is expressed as kg per metric hp-hour • Thermal Efficiency: It is the ratio of the horse power output of an engine to the fuel horse power
  22. 22. Comparison between Two stroke and four stroke cycle Engines Two Stroke Engine • One power impulse for every tow stroke of the piston • For the same size of engine it gives twice the power of four stroke engine • Size of the fly wheel is comparatively smaller • Thermal efficiency is low • Weight per HP is low • Only high speed type engines are available • Engine can be operated in both direction(clockwise, and anti clockwise) • Valves are not required for intake and exhaust operation. Four Stroke Engine • One power impulse for every four stroke of the piston • For the same size of engine it gives only half the power of two stroke engine. • Size of the fly wheel is comparatively larger • Thermal efficiency is higher • Weight per HP is comparatively high • All types.low, medium and high speed engines are available • Engine can be operated in only one direction • Valves are required to let the gases in or out
  23. 23. Comparison between Diesel and Petrol Engine Diesel Engine • Diesel fuels are used. • Filtered air is taken during intake stroke • Compression ignition takes place with injected fule • Air fuel ratio is not constant because of constant air inlet • Compression ratio varies between 14-20:1 with high compression pressure and temperature • Specific fuel consumption is about 0.2 kg /bhp/hr • 4.5 litres of fuel produce 20 hp-hr Carburettor(Petrol)Engine • Petrol,Kerosene are used • Mixture of air and fuel is taken during intake stroke • Spark ignition with electric spark plug takes place with compressed mixture • Air fuel ratio is constant as 15:1 • Compression ratio varies between 4.5-8:1 with low compression pressure and temperature • Specific fuel consumption is about 0.29kg/bhp/hr • 4.5 litres of fuel produce 12hp-hr
  24. 24. Comparison contd….. Diesel Engine • Thermal Efficiency varies between 32-38 % • Diesel engine develops more torque when it is heavely loaded • It runs at lower combustion gas temperature on part load • Engine weight per horse power is high • Initial cost is high • Operating cost is low Petrol Engine • Thermal Efficiency varies between 25-32 % • This characteristic is not present in petrol engine • Combustion gas temperature is slightly higher under part load • Engine weight per horse power is comparatively low • Initial cost is low • Operating cost is comparatively high
  25. 25. Systems in Tractor Engines • Fuel Supply and Circulation System • Air Cleaning and supplySystem • Lubrication System • Engine cooling System • Ignition System-compression ignition as well spark ignition system • Electrical System • Engine governing System for constant engine speed under varying loads • Power Transmission System
  26. 26. External combustion Steam engine tractor
  27. 27. Modern Farm Tractor
  28. 28. Power tiller
  29. 29. Farm Tractor
  30. 30. Live action of multicylinder petrol engine
  31. 31. Engine
  32. 32. Tractor engine
  33. 33. Big and multi use Tractoe
  34. 34. Tractor Engine
  35. 35. Two wheel Tractor
  36. 36. Fram Tractor
  37. 37. Fuel Supply and circulation System • Components and their function of Fuel supply and circulation system • Fuel Tank • Fuel supply pipes • Fuel Filters • Carburettor only in case of petrol engine to mix the air and fuel in a predetermined air fuel ratio of 15:1. • Fuel feed pump or fuel supply pump • Priming pump-hand operated pump to take air out from the fuel supply system by bleeding action with air bubbles • Pressure pump with pressure gauge • Fuel Injection pump • Fuel control,regulation valve or check valve,bleeding valve etc • Fuel injection nozzle or fuel injector.
  38. 38. Fuel supply System contd… • Fuel Tank-  Used to store the fuel in a safety manner Protect the stored fuel from dirt, water,or any other unlike materials. Should be cleaned throughly after every 200 working hours by draining out all the fuel. Should be filled with fuel after days works and keep air tight
  39. 39. Contd… • Fuel pipes  Conncet fuel tank with fuel filters,fuel pump,fuel injection pump and injection nozzles to supply and circulate fuel in case of single cylinder as well as multi cylinder engines • Fuel feed or fuel supply pump.  Lies between primary filter and fuel injection pump  Supply and circulate fuel from fuel tank via primary filter to fuel injection pump at a lower pressure of 2 kg/sq.cm  Plunger typed- driven by camshaft as connected by push rod with camshaft  When engine starts it gets power to self working condition
  40. 40. Contd.. • Fuel Filters-  Primary fuel filter- located between fuel tank and fuei supply pump  Secondary fuel filters-located between fuel pump and fuel injection pump  Consists of fine graded filter elements made of special treated paper of different qualities,filter bowl,drain plug ,air bleeding serews,inlet outlet points for pipe fiting etc  Clean the fuel by filtering action not allowing the derts,vapors, particles air bubbles etc of size greater than 0.25-1mm dia (nozzle hole size) into the system  Filter the dirt of size of 5-2 micron not allowing to fuel injection pump  Replace the filter and filter elements after each 125 working hour
  41. 41. Contd… • Fuel Injection Pump Connected to engine camshaft for auto functioning when engine start Supply the fuel to the injection nozzle with predetermined time under the pressure of 126- 175 kg/sq.cm or more Circulate the fuel equally to all nozzle of multi cylinder engines as well as single cylinder engines Re-circulate the excess fuel not utilized by injection nozzle to fuel tank.
  42. 42. Contd… • Fuel injection nozzles or fuel injectors  Located at engine head or cylinder head  Spray the fuel with high pressure into combustion chamber  Multiple nozzle hole are more effective than single one to spray fuel  Leak off pipe from injectors access the overflow fule to fuel tank  Fuel is sprayed in predetermined time and pressure with compression stroke.  Nozzle valve is active to regulate the fuel spray to combustion chamber
  43. 43. Air cleaning System • Pre-cleaner,Air cleaner Air cleaners in all farm tractors are equipped with pre cleaners as air intake system to remove larger particles of dirt and foreign materials like straw,chaff,leaves etc Averege tractor uses 9000 liter of air for each liter of diesel consumed under normal condition • Two types of air cleaner are in use Oil soaked element type-used in crankcase ventilation system and in small stationary engine where less dusty condition is existed
  44. 44. Air cleaning contd…  Oil bath type-used in most commonly in farm tractors.  Consist of oil bowl,filter screens,precleaner,air inlet and out let pipe system  Dusty air is allowed through the center pipe dipped into oil to pass the air from oil as an oil bath then allow upward to filtering element where oil is entraped by filtering element ,drops back to oil bowl and fresh air goes to the engine.  Oil might need a change between 8-60 working hour when dust sedimentation exceed 5mm at the bottom of the bowl
  45. 45. Lubricating Systems • Lubraction is the oiling and greasing of different moving parts and systems of IC engines or tractors • Consist of oil chamber,oil pump,oil filter,pressure gauge, regulating valve,bypass relief valves,drain plug etc • Essential for all moving parts of tractor engine to performs the following functions  Reduce wear and tear of moving parts  Reduce power needed to overcome frictional resistances between two relatively moving parts such as shaft bearings gears,etc  Removes or absorbs heat from piston and other parts
  46. 46. Lubrication contd.. • It is accomplished by two systems  Splash system-lubricating oil is splashed or sprayed in moving parts periodically with self functioning when engine starts Force feed system by oil pump-oil is supplied under pressure to reach to all moving parts Gear pump driven by camshaft forces engine oil from crankcase(oil chamber) to all moving parts automatically when engine start to run
  47. 47. Contd.. • The daily and periodic lubrication of all system is explained in the Operator’s Mannual of the Tractors to ensure trouble free operation and long life of tractor, given by Tractor Manufacturers • Recommended grade of lubricants like grease,mobil,gear oil etc is essential to use as given in operational mannual • Grade of lubricants and changing of lubricants- mobile, Castrol oil ,grease is also periodic as given in operational mannual by the manufracturers.
  48. 48. Showing lubrication system
  49. 49. Cooling System • As it is the requirement that engine should be run at an optimum temperature to ensure the best performance • The purpose of cooling system is to maintain the correct engine operating temperature and dissipate surplus heat resulting from cumbustion of fuel in engine cylinder • The cooling system of IC engine should maintain the engine temperature at 71-80 degree C for petrol engine and 88-90 degree C for diesel engine • Types of cooling system  Water cooling system-used for bigger engine  Air cooling system-used for smaller engine
  50. 50. Cooling system…. • Types of water cooling system  Thermosiphon cooling system- -Used in tractors and stationary engines -Consists of a radiator,water jacket,fan, temperature gauge and hose pipe connection -It works on the principle that heated air surrounding the engine cylinder gets lighter in weight and rises up -Hot water goes to radiator where it passes through tubes surrended by air -Since water jacket and radiator are connected at the top and bottom a circulation of water takes place. -A fan driven by a pully mounted on crankshaft is located between radiator and engine sucks air through radiator tub thus cooling the radiator water
  51. 51. Cooling system contd… • Forced circulation cooling system/pressurized cooling system Consist of radiator,fan,fan belt,water jacket,water pump,thermostat,temperature gauge and hose pipe to complete the cooling system Water is pumped to radiator where it loose heat by radiation to the air outside Water circulation between engine chamber and radiater is controlled by thermostat valve placed at cylinder head to maintain the temperature of 74-80 degree Centigrate
  52. 52. Live action of multicylinder petrol engine

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