Basic Mechanical Engineering - IC engines

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Basic Mechanical Engineering - IC engines

  1. 1. M S Steve Assistant professor Dept of Mechanical Engineering Amal Jyothi College of Engineering 1 msstevesimon@gmail.com
  2. 2. Heat Engines Absorb energy in the form of heat Convert part of it into work Reject balance as heat 2 msstevesimon@gmail.com
  3. 3. Combustion 3 msstevesimon@gmail.com
  4. 4. Heat Engines 1. 2. 4 External Combustion Engines – steam engine Internal combustion Engines – automobile engine msstevesimon@gmail.com
  5. 5. msstevesimon@gmail.com Internal Combustion Engine  Burns fuel and air in enclosed space  Produces hot burned gases  Converts some of this heat into useful work  Allows heat to flow from hot engine to cold outside air Nikolaus Otto patented the 4stroke engine when he was only 34! 5
  6. 6. Internal Combustion Engines are those heat engines where the combustion of the fuel takes place inside the engines 6 msstevesimon@gmail.com
  7. 7. Advantages of I C Engines 1. 2. 3. 4. 7 High thermal efficiencies ( 30 to 35%) Higher power to weight ratio Compact and suitable for portable applications Quick-starting and simple in construction msstevesimon@gmail.com
  8. 8. Disadvantages of I C Engines 1. 2. 8 Since fuel combustion occurs in the cylinder, consequent very high temperatures of engines necessitates engine cooling arrangements High temperatures restrict ICEngines to be single-acting, reducing the power strokes per revolution msstevesimon@gmail.com
  9. 9. Classification of IC Engines According to:  Fuel used  Strokes per cycle  Thermodynamic cycle  Speed of engine  Method of ignition  Method of cooling  Method of governing  Arrangement of engine cylinders  Number of cylinders  Application 9 msstevesimon@gmail.com
  10. 10. Arrangement of Cylinders 10
  11. 11. Arrangement of Cylinders 11 msstevesimon@gmail.com
  12. 12. Comparison of Petrol and Diesel Engines 1. 2. 3. 4. 5. 6. 7. 8. 9. 12 PETROL ENGINE Works on Otto Cycle Fuel-air mixture is admitted during suction stroke Spark ignition Low compression ratios (6 to 10) Lower engine efficiency Higher fuel consumption Lower engine vibrations and noise High running cost Light duty application 1. 2. 3. 4. 5. 6. 7. 8. 9. DIESEL ENGINE Works on Diesel Cycle Fuel is injected at the end of compression stroke Compression ignition High compression ratios (10 to 20) Higher engine efficiency Lower fuel consumption Higher engine vibrations and noise Low running cost Heavy duty application msstevesimon@gmail.com
  13. 13. IC Engine 13 msstevesimon@gmail.com
  14. 14. 14 msstevesimon@gmail.com
  15. 15. IC Engine Parts 1. 2. 3. 4. 5. 6. 15 Cylinder Head Cylinder Block and Liner Piston Connecting Rod Crankshaft Crank Case and Sump msstevesimon@gmail.com
  16. 16. Cylinder head 16 msstevesimon@gmail.com
  17. 17. Engine valves 17 msstevesimon@gmail.com
  18. 18. Valve mechanism 18 msstevesimon@gmail.com
  19. 19. Piston assembly 19 msstevesimon@gmail.com
  20. 20. Crank case 20 msstevesimon@gmail.com
  21. 21. Crank shaft assembly 21 msstevesimon@gmail.com
  22. 22. Four Stroke and Two Stroke Engines 22 msstevesimon@gmail.com
  23. 23. Four Stroke I C Engine In a four stroke I C Engine, one cycle of operation is completed in four strokes of the piston in the engine cylinder The strokes are: 1. Suction (Induction) stroke 2. Compression Stroke 3. Power Stroke 4. Exhaust Stroke 23 msstevesimon@gmail.com
  24. 24. Suction (Induction) stroke 24 msstevesimon@gmail.com
  25. 25. Compression Stroke 25 msstevesimon@gmail.com
  26. 26. Power Stroke 26
  27. 27. Exhaust Stroke 27
  28. 28. The four-stroke engine Spark plug Exhaust valve Inlet valve Cylinder Piston 28 msstevesimon@gmail.com
  29. 29. The four-stroke engine Inlet valve open INDUCTION STROKE 29 msstevesimon@gmail.com
  30. 30. The four-stroke engine Inlet valve open Piston down 30 msstevesimon@gmail.com INDUCTION STROKE
  31. 31. The four-stroke engine Charge in Inlet valve open Piston down 31 msstevesimon@gmail.com INDUCTION STROKE
  32. 32. The four-stroke engine Charge in Inlet valve open Piston down 32 msstevesimon@gmail.com INDUCTION STROKE
  33. 33. The four-stroke engine Charge in Inlet valve open INDUCTION STROKE 33 msstevesimon@gmail.com
  34. 34. The four-stroke engine Exhaust valve closed Inlet valve closed COMPRESSION STROKE Piston up 34 msstevesimon@gmail.com
  35. 35. The four-stroke engine Exhaust valve closed Inlet valve closed Piston up 35 msstevesimon@gmail.com COMPRESSION STROKE
  36. 36. The four-stroke engine Exhaust valve closed Inlet valve closed Piston up COMPRESSION STROKE 36 msstevesimon@gmail.com
  37. 37. The four-stroke engine Exhaust valve closed Inlet valve closed BANG POWER STROKE 37 msstevesimon@gmail.com
  38. 38. The four-stroke engine Exhaust valve closed Inlet valve closed Piston down powerfully 38 msstevesimon@gmail.com POWER STROKE
  39. 39. The four-stroke engine Exhaust valve closed Inlet valve closed POWER STROKE 39 Piston down powerfully msstevesimon@gmail.com
  40. 40. The four-stroke engine Exhaust valve closed Inlet valve closed POWER STROKE 40 msstevesimon@gmail.com
  41. 41. The four-stroke engine Inlet valve closed Exhaust valve open EXHAUST STROKE 41 msstevesimon@gmail.com
  42. 42. The four-stroke engine Inlet valve closed Exhaust valve open Exhaust gases out Piston up 42 msstevesimon@gmail.com EXHAUST STROKE
  43. 43. The four-stroke engine Inlet valve closed Exhaust valve open Exhaust gases out Piston up EXHAUST STROKE 43 msstevesimon@gmail.com
  44. 44. The four-stroke engine Inlet valve open Exhaust valve closed INDUCTION STROKE 44 msstevesimon@gmail.com
  45. 45. And so the cycle continues!! 45 msstevesimon@gmail.com
  46. 46. 46 msstevesimon@gmail.com
  47. 47. 1. Induction Stroke  Engine pulls piston out of cylinder  Low pressure inside cylinder  Atmospheric pressure pushes fuel and air mixture into cylinder  Engine does work on the gases during this stroke 47 msstevesimon@gmail.com
  48. 48. Engine – Stroke 1 Fuel and air mixture after induction stroke: Pressure Temperature 48 = Atmospheric = Ambient msstevesimon@gmail.com
  49. 49. 2. Compression Stroke  Engine pushes piston into cylinder  Mixture is compressed to high pressure and temperature  Engine does work on the gases during this stroke 49 msstevesimon@gmail.com
  50. 50. Engine – Stroke 2 Fuel and air mixture after compression stroke: Pressure Temperature 50 = High = Hot msstevesimon@gmail.com
  51. 51. 3. Power Stroke  Mixture burns to form hot gases  Gases push piston out of cylinder  Gases expand to lower pressure and temperature  Gases do work on engine during this stroke 51 msstevesimon@gmail.com
  52. 52. Engine – Stroke 3 Burned gases after ignition: Pressure Temperature 52 = Very high = Very hot msstevesimon@gmail.com
  53. 53. Engine – Stroke 4 Burned gases after power stroke: Pressure Temperature 53 = Moderate = High msstevesimon@gmail.com
  54. 54. 4. Exhaust Stroke  Engine pushes piston into cylinder  High pressure inside cylinder  Pressure pushes burned gases out of cylinder  Engine does work on the gases during this stroke 54 msstevesimon@gmail.com
  55. 55. msstevesimon@gmail.com Two Stroke Engines 55
  56. 56. 56 msstevesimon@gmail.com
  57. 57. 57 msstevesimon@gmail.com
  58. 58. Two Stroke I C Engine In a two stroke I C Engine one cycle of operation is completed in two strokes of the piston in the engine cylinder Stroke 1: Scavenging and Compression Stroke 2: Power and Exhaust 58 msstevesimon@gmail.com
  59. 59. msstevesimon@gmail.com Scavenging and Compression 59
  60. 60. Power and Exhaust 60
  61. 61. 61
  62. 62. Advantages of Two Stroke engines 1. 2. 3. 4. 5. 6. 62 One power stroke every revolution of crankshaft results in high power to weight ratio Torque is more uniform needing lighter flywheel Simpler in construction due to absence of valves and valve gear Friction loss is less giving higher mechanical efficiency Lower initial cost Easier starting msstevesimon@gmail.com
  63. 63. Disadvantages of Two Stroke engines Overall efficiency is less due to: a) Inadequate scavenging as some combustion products remain in cylinder b) Loss of fresh charge during scavenging c) Less effective compression ratio for same stroke length 2. Engine overheating due to power stroke in every revolution 3. High lubricating oil consumption 4. Exhaust is noisier 1. 63 msstevesimon@gmail.com
  64. 64. Comparison of Four Stroke and Two Stroke Engines FOUR STROKE ENGINE 1. 2. 3. 4. 5. 6. 7. 64 One cycle in 4 strokes of piston or 2 revolutions of crankshaft Valves are used for charge admission and exhaust One power stroke in two revolution causing torque fluctuations needing heavy flywheel Low power to weight ratios Higher overall efficiency Complex construction due to valve gear Heavy duty applications TWO STROKE ENGINE 1. 2. 3. 4. 5. 6. 7. One cycle in 2 strokes of piston or one revolution of crankshaft No valves but ports are used for admission and exhaust One power stroke in one revolution causing smoother torque and consequent lighter flywheel Higher power to weight ratios Lower overall efficiency due to loss of fresh charge Simpler construction Light duty applications msstevesimon@gmail.com
  65. 65. I C Engine Systems 65
  66. 66. I C Engine Systems 1. 2. 3. 4. 5. 66 Air & Exhaust System Fuel Systems Ignition Systems Cooling Systems Lubrication Systems msstevesimon@gmail.com
  67. 67. AIR SYSTEM FOR PETROL ENGINE 67 msstevesimon@gmail.com
  68. 68. AIR SYSTEM FOR PETROL ENGINE AIR FROM ATM AIR FILTER Carburettor Product of combustion to atm 68 msstevesimon@gmail.com Engine SILENCER
  69. 69. FUEL SYSTEMS  Petrol Engines  Diesel Engines 69 msstevesimon@gmail.com
  70. 70. Fuel Systems Petrol Engines Correct quantity of petrol is mixed with air in carburettor before being admitted into cylinder during suction stroke 70 msstevesimon@gmail.com
  71. 71. FUEL SYSTEM FOR PETROL ENGINE AIR FROM ATM AIR FILTER combu stion Fuel storage tank 71 Fuel Pump Fuel Filter msstevesimon@gmail.com Carburettor Engine
  72. 72. FUEL SYSTEM FOR PETROL ENGINE 72 msstevesimon@gmail.com
  73. 73. FUEL SYSTEM FOR DIESEL ENGINE AIR FROM ATM Low pressure pump filter filter AIR FILTER High pressure pump Fuel storage tank Fuel Injector Product of combustion to atm SILENCER Engine 73 msstevesimon@gmail.com
  74. 74. FUEL PUMP 74
  75. 75.  It pumps fuel from storage tank to carburetor  Actuated by cam, it is in touch with rocker arm  As the link is pulled downwards diaphragm will move down and fuel will enter the chamber  Inlet and Exhaust valves are one way valves 75 msstevesimon@gmail.com
  76. 76. One-way Inlet Valve One-way Outlet Valve Diaphragm Driving Cam 76 Diaphragm Pump
  77. 77. Air Filter Carburettor Cockpit Gauge Inlet Tank Pump 77 PETROL ENGINE – Carburettor Fuel System Exhaust
  78. 78. 78 msstevesimon@gmail.com
  79. 79. 79 msstevesimon@gmail.com
  80. 80. JET VENTURI FLOAT NEEDLE VALVE AIR VENT FUEL LEVEL FLOAT FLOAT CHAMBER 80 SIMPLE CARBURETOR WORKING msstevesimon@gmail.com FUEL FEED @ PUMP
  81. 81.  Major function of carburetor is to provide air fuel mixture  Basic principle : When a volatile fuel is placed in the passage of high velocity air, the fuel gets vaporized at a faster rate  Arrangement: • • • • • 81 Jet and fuel nozzle Venturi tube & venturi throat Float chamber Throttle valve Float , float needle, air vent msstevesimon@gmail.com
  82. 82. Working 1. 2. Petrol is pumped into the float chamber, level of petrol is maintained by a float arrangement Suction stroke of engine causes air flow through venturi tube. 3. VELOCITY of air at throat will increase & PRESSURE will decrease at JET point(will be less than Atm. Pressure) 4. In float chamber the pressure acting is Atm. Pressure, due to this pressure difference fuel will flow from FLOAT CHAMBER to the JET 5. Function of throttle is to control speed and power to engine, more the throttle is closed flow of air & fuel mixture to the cylinder is less 82 msstevesimon@gmail.com
  83. 83. FUEL FLOW AIR FLOW AIR FLOW AIR/FUEL MIXTURE FLOWS TO ENGINE AIR IS SUCKED THROUGH VENTURI ….. A PISTON MOVING DOWN ON SUCTION STROKE THE LOWER AIR PRESSURE PULLS FUEL THROUGH THE JET FUEL LEVEL DROPS MOVING AIR HAS LOWER PRESSURE 83 SIMPLE CARBURETOR WORKING msstevesimon@gmail.com
  84. 84. FUEL LEVEL DROPPING LOWERS FLOAT PULLING AIR INTO FLOAT CHAMBER FUEL LEVEL DROPS 84 SIMPLE CARBURETOR WORKING
  85. 85. FUEL LEVEL DROPPING LOWERS FLOAT FUEL LEVEL RISING FORCES THE NEEDLE VALVE CLOSED AND ALLOWS FUEL TO ENTER FLOAT CHAMBER FROM PUMP FUEL LEVEL DROPS 85 SIMPLE CARBURETOR WORKING
  86. 86. FUEL LEVEL RISING FORCES THE NEEDLE VALVE CLOSED FUEL IS PULLED OUT OF THE FLOAT CHAMBER ONLY WHEN PISTON IS ON THE INDUCTION STROKE 86 SIMPLE CARBURETOR WORKING
  87. 87. We now need to look at controlling the air/fuel mixture flowing into the engine Controlling the air/fuel mixture means controlling the engine The carburettor part which controls the flow is…. THE THROTTLE 87 msstevesimon@gmail.com
  88. 88. THROTTLE VALVE 88 SIMPLE CARBURETOR WORKING
  89. 89. THROTTLE VALVE THIS WOULD BE A HIGH THROTTLE SETTING OR ‘FULL –POWER’ OPEN THROTTLE ALLOWS VENTURI TO WORK AT MAXIMUM EFFICIENCY 89 SIMPLE CARBURETOR WORKING
  90. 90. LOW THROTTLE SETTING - CALLED ‘IDLE’ OR ‘TICK-OVER’ ALMOST CLOSED THROTTLE MEANS THE VENTURI DOES NOT WORK VERY WELL LOW AIR FLOW MEANS VERY LITTLE OR NO FUEL/AIR MIXING IN THE VENTURI SO AN ALTERNATIVE AND EFFECTIVE VENTURI NEEDS TO BE FOUND 90 SIMPLE CARBURETOR WORKING
  91. 91. LOW THROTTLE SETTING - CALLED ‘IDLE’ OR ‘TICK-OVER’ EDGE GAPS BECOME THE VENTURI FOR THE LOW AIR FLOW AT IDLE - SLOW RUNNING JET CONTROLS FUEL FLOW T 91 SIMPLE CARBURETOR WORKING
  92. 92. 92 msstevesimon@gmail.com
  93. 93. LIMITATIONS OF CARBURETTOR • Distribution of air /fuel mixture to cylinder is not uniform • Construction of venturi causes low volumetric efficiency • There is a loss of volumetric efficiency also due to restricted flow of mixture in various parts such as chokes, tubes, jets, throttle valve, inlet pipe bends, etc. All the above limitations of carburettor can be avoided by introducing the fuel through injection rather than the carburettor 93
  94. 94. FUEL INJECTION PUMP A fuel injection pump is used to supply precisely metered quantity of diesel under high pressure to the injectors at the correct time. 94 msstevesimon@gmail.com
  95. 95. 95
  96. 96. 96
  97. 97. 97
  98. 98. FUEL PUMP Spring Delivery valve Fuel overflow port Inlet port Barrel Rack plunger 98 msstevesimon@gmail.com
  99. 99. barrel  Barrel houses the inlet port and fuel overflow port 99
  100. 100. Plunger  Plunger driven by cam & tappet  Plunger reciprocates in a barrel & fuel enters thru inlet port  Plunger have a vertical and helical groove which help in determining the amount of fuel supplied to the fuel injector 100 msstevesimon@gmail.com
  101. 101. • Delivery valve is a non return valve, kept in position by a spring. When the Pr. In the barrel exceeds a predetermined value and valve opens against the compression of the spring and the pressure of the fuel above. Fuel pump is connected to the fuel injector through a passage 101 msstevesimon@gmail.com
  102. 102. Working  When the plunger is at bottom the fuel inlet & overflow     102 ports are uncovered and filtered fuel is forced into the barrel Both ports are covered when the plunger moves upwards Fuel will get compressed when the plunger moves further forward The high pressure lifts the delivery valve and fuel flows out thru the delivery valve With further rise of the plunger the overflow port is uncovered by the plunger and pressure drops msstevesimon@gmail.com
  103. 103.  The quantity of fuel pumped can be varied by the angular position of the helical groove relative to the inlet port 103
  104. 104. 104 msstevesimon@gmail.com
  105. 105. Diesel Fuel Pump  Plunger reciprocates on a barrel(hollow cylinder like     105 arrangement) A rectangular helical groove in the plunger which extends from top to another helical groove When the plunger is at bottom -- fuel inlet and overflow port are open,--fuel will come inside the barrel When the plunger moves up– both ports are closed –and fuel inside the barrel get compressed Due to the high pressure of compressed fuel delivery valve will get opened msstevesimon@gmail.com
  106. 106. FUEL INJECTOR 106 msstevesimon@gmail.com
  107. 107. FUEL INJECTOR A fuel injector is used to inject the fuel in the cylinder in atomised form and in proper quantity. Fuel injectors are available in several designs. Main components of fuel injectors are : NOZZLE VALVE BODY SPRING The nozzle is its main part which is attached to the nozzle holder. Entry of fuel in the injector is from the fuel injection pump. 107 msstevesimon@gmail.com
  108. 108. 108 msstevesimon@gmail.com
  109. 109. FUEL INJECTION NOZZLE 109 msstevesimon@gmail.com
  110. 110. Spray Structure 110
  111. 111. PARTS OF FUEL INJECTOR 1. 2. 3. 4. 5. 6. 7. 8. 9. 111 Nozzle valve Nozzle body Spring spindle Adjusting screw Lock nut Passage Nozzle Leak of connection
  112. 112.  Nozzle valve is fitted in a nozzle body.  The spring retains the valve in its seating through a spindle.  Adjusting screw and lock nut- to adjust the lift of the nozzle 112 msstevesimon@gmail.com
  113. 113. Working  High pressure fuel from the fuel pump enters the injector through the passage and lift the nozzle valve  Fuel travels down the nozzle and is injected into the engine cylinder in the form of fine spray  When the fuel pressure drops the spring force overcomes the fuel pressure and the valve get closed  Any leakage of the fuel at the end of the compression is fed back to the fuel pump suction chamber by the leak off pipe 113 msstevesimon@gmail.com
  114. 114. FUEL INJECTOR 114 msstevesimon@gmail.com
  115. 115.  Nozzle valve is held on its seat by a spring which exerts pressure through a spindle  Fuel from fuel pump enters the passage and lifts the nozzle valve  then the fuel will sprayed through the nozzle and is injected into the engine  When pressure drops the nozzle valve will occupy in its seat under the compression of the spring 115 msstevesimon@gmail.com
  116. 116. Ignition Systems  Ignition process in Petrol Engines requires an electric spark produced at the spark plug.  This spark is generated by an electric discharge produced by the ignition system.  Ignition systems in petrol engines are classified as : 1.Battery ignition system. 2.Magneto ignition system • The difference between the two systems is in the source of primary voltage. 116 msstevesimon@gmail.com
  117. 117. Ignition systems  Basic requirements of an ignition systems  A source of electrical energy  A device for boosting the low voltage to produce high voltage  A device for timing and distributing the high voltage to each spark plug 117 msstevesimon@gmail.com
  118. 118. Battery Ignition System. 118
  119. 119. Battery ignition system  It is also called coil ignition system.  The source of energy to the primary windings is a 6V or 12V battery.  As the number of windings in the secondary is 50 to 100 times more than that of the primary , the output voltage induced will be of the order of 10000v to 20000V. 119 msstevesimon@gmail.com
  120. 120. Magneto Ignition System 120
  121. 121. Magneto ignition system  The source of energy is either rotating magnets with fixed coils or rotating coils with fixed magnets.  The rapid collapse and reversal of magnetic field induces a very high voltage in the secondary winding.  It is generally employed in racing cars, motor cycles etc. 121 msstevesimon@gmail.com
  122. 122. Spark plug TaskThe spark plug ignite the suctioned and compressed fuel-air mixture due to arcing between the electrodes. FunctionThe ignition voltage travels to the spark plug from directly Connected ignition coils or over the ignition lines from the Ignition coils causing arcing in the air gap between the center and ground electrodes. 122 msstevesimon@gmail.com
  123. 123. The Spark Plug Spark plug is located in the cylinder head, it ignites the air and fuel mixture. Has centre and side electrodes, with an air gap between them. Terminal Insulator Hex Centre electrode receives coil voltage. Metal shell Side electrode is grounded. High voltage jumps the air gap, creating a spark. Insulator prevents high voltages from shorting to ground. 123 Gasket Thread Side electrode Centre electrode Gap Next >
  124. 124. Lubricating Systems Purpose: 1. To reduce friction and wear 2. To provide sealing between piston and cylinder 3. To cool piston heads, valves, etc. 4. To wash away carbon and metal particles 124 msstevesimon@gmail.com
  125. 125. Lubrication Systems: Petroil lubrication Wet sump lubricating system 1. 2. 1. 2. 3. 125 Splash lubrication Pressure lubrication Dry sump lubricating system msstevesimon@gmail.com
  126. 126. Petrol Lubrication System  This system of lubrication is used in scooters and motor cycles.  About 3% to 6% of lubricating oil is added with petrol in the petrol tank.  The petrol evaporates when the engine is working. The lubricating oil is left behind in the form of mist.  The parts of the engine such as piston cylinder walls, connecting rod are lubricated by being wetted with the oil mist. 126 msstevesimon@gmail.com
  127. 127. Wet sump lubrication system  The splash system is used only on small four-stroke-cycle engines.  As the engine is operating, dippers on the ends of the connecting rods enter the oil supply, pick up sufficient oil to lubricate the connectingrod bearing, and splash oil to the upper parts of the engine.  The oil is thrown up as droplets, or fine spray, which lubricates the cylinder walls, piston pins and valve mechanism.  In the pressure-feed system, oil is forced by the oil pump through oil lines and drilled passageways.  The oil, passing through the drilled passageways under pressure, supplies the necessary lubrication for the crankshaft main bearings, the connecting-rod bearings piston-pin bushings, camshaft bearings, valve lifters, valve push rods, and rocker studs. 127 msstevesimon@gmail.com
  128. 128. Splash lubrication  Simplest of all types, used only for small capacity engines. 128 msstevesimon@gmail.com
  129. 129. msstevesimon@gmail.com Pressure lubrication 129
  130. 130. Dry Sump Lubrication System  In a wet sump, the oil pump sucks oil from the bottom of the oil pan through a tube, and then pumps it to the rest of the engine.  In a dry sump, extra oil is stored in a tank outside the engine rather than in the oil pan. There are at least two oil pumps in a dry sump -- one pulls oil from the sump and sends it to the tank, and the other takes oil from the tank and sends it to lubricate the engine. The minimum amount of oil possible remains in the engine. 130 msstevesimon@gmail.com
  131. 131. Dry sump lubrication • The supply of oil is from an external tank. • 131 An oil pump is employed to circulate the oil under pressure ,from the tank to various bearings of the engine.
  132. 132. Functions of a Lubricant  Lubricant reduces friction between moving part.  It reduces wear and tear of the moving parts.  It minimizes power loss due to friction.  It provides cooling effect. While lubricating it also carries some heat from the moving parts and delivers it to the surroundings through the bottom of the engine (crank case).  It helps reduce noise created by the moving parts. 132 msstevesimon@gmail.com
  133. 133. THE COOLING SYSTEM 133 msstevesimon@gmail.com
  134. 134. Purpose of cooling  To regulate the engines internal temperature  To remove excess heat from the engine  To prevent heat to the passenger compartment  To Control temperature of hot combustion,4000 degree temps. could seriously damage engine parts.  Cool Trans fluid & Oil 134 msstevesimon@gmail.com
  135. 135. Cooling Systems  Intense heat is generated during the combustion of fuels inside the engine cylinder.  30% of heat generated is converted into mechanical work & 40% is carried away by exhaust gases to the atmosphere.  The remaining part of heat (30%) will be absorbed by the engine parts which leads to overheating of these parts.  In order to avoid the problem of overheating it is essential to provide some kind cooling systems. 135 msstevesimon@gmail.com
  136. 136.  The two important characteristics of cooling systems for the efficient working are: (i)It should not remove more than 30% of heat generated.(larger amount of heat removal reduces the thermal efficiency) (ii)The rate of cooling should not be constant.(the rate of cooling should increase with increase in heat generated) 136 msstevesimon@gmail.com
  137. 137.  Two types of cooling systems used in IC engines are: 1.Air cooling system 2.water cooling system 137 msstevesimon@gmail.com
  138. 138. Air cooling  The heat is dissipated directly in to the atmospheric air by conduction through cylinder walls.  The rate of cooling is increased by increasing the outer surface area of the cylinder by providing radiating fins & flanges.  Normally it is used for the engines of motor cycles , scooters etc. 138 msstevesimon@gmail.com
  139. 139.  To increase the surface area exposed fins are provided  In some cases blower is provided to increase the heat tr. rate 139 msstevesimon@gmail.com
  140. 140. Air cooling system 140
  141. 141. Air cooling  Heat is dissipated to the surrounding air around the cylinder  Basic principle- to have continuous flow air around parts which are to be cooled  The heat dissipated depends on :  The surface area of the metal, in contact with the air flow  The Temp difference between the surface & the air  Thermal Conductivity of the metal 141 msstevesimon@gmail.com
  142. 142. Advantages of Air-cooled Engines:  Air-cooled engines are smaller and lighter because they don’t need to house any of those parts like the Water cooled engines  In some climates, water has the tendency to freeze and this is a problem for water-cooled engines.  Air-cooled engines warm up quickly and are easy to maintain. Disadvantages of Air-cooled engines:  The cooling tends to be uneven and leads to cylinder distortion.  It is almost impossible to manage with air-cooling if the number of cylinders increases beyond two.  The fins vibrate sometimes leading to a lot of noise. 142 msstevesimon@gmail.com
  143. 143. Water cooling system.  It is also called thermosyphon system of cooling .  Water is circulated through water jackets around each of the combustion chambers.  The circulating water is cooled by the air drawn through radiator by a fan 143 msstevesimon@gmail.com
  144. 144. Liquid cooling (water cooling)  Cooling medium – water  Water circulated through the passages around the main components  Passages – water jackets  Water circulation- pump or by gravity force 144 msstevesimon@gmail.com
  145. 145.  Water after passing through the jackets flows to a radiator.  Radiator cools hot water with the help of moving air around the radiator tubes  Fans are provided to increase the heat transfer rate  This system also uses a thermostat to control the flow of the coolant  Antifreeze added to avoid freezing of coolant- ethylene glycol 145 msstevesimon@gmail.com
  146. 146. Water cooling system 146 msstevesimon@gmail.com
  147. 147. Water Jackets  Surrounds the cylinders with water passage.  Absorbs heat from the cylinder wall.  Pump move water to radiator where heat is exchanged to the air. 147 msstevesimon@gmail.com
  148. 148. msstevesimon@gmail.com Radiators  A radiator is a heat exchanger.  Tube and fin style the most popular.  Made of copper and brass or aluminum and plastic. 148
  149. 149.  Its job is to block the flow of coolant to the radiator until the engine has warmed up.  When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens.  By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions. 149 msstevesimon@gmail.com
  150. 150. INJECTION METHODS 150
  151. 151. 151 msstevesimon@gmail.com
  152. 152. TYPES OF CI INJECTION SYSTEMS 152
  153. 153. COMMON RAIL DIRECT INJECTION (CRDI) 153 msstevesimon@gmail.com
  154. 154. 154 msstevesimon@gmail.com
  155. 155. COMMON RAIL 155
  156. 156. Working  HP fuel pump maintains fuel in the common rail at a pressure of about 200 MPa.  Common rail branches off to ECU controlled injector valves  Valve contains precision machined nozzles and a plunger driven by solenoid valves  ECU controls the timing and quantity of fuel injected depending on the load conditions 156 msstevesimon@gmail.com
  157. 157. Advantages of CRDI  Higher efficiency due to variable injection timing  Better combustion at low speeds  Better power balance- reduced vibration  Lesser moving parts  Compact engine 157 msstevesimon@gmail.com
  158. 158. 158
  159. 159. AIR FURL SYSTEM IN SI (PETROL) ENGINES 159
  160. 160. Gasoline direct injection  Petrol Direct Injection or Direct Petrol Injection or Spark Ignited Direct Injection (SIDI) or Fuel Stratified Injection (FSI) 160 msstevesimon@gmail.com
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  162. 162. Components of GDI engine  Pumping element  Metering element  Mixing element  Mixture control  Distributing element  Ambient control 162 msstevesimon@gmail.com
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  164. 164. MULTI POINT FUEL INJECTION  Petrol vehicles used carburettor for supplying the air fuel mixture in correct ratio to cylinders in all rpm ranges.  Carburettor achieves this by breaking up fuel into minute particles and mixing it with air.  But this process may not always be perfect and might reduce the performance of the engine.  Therefore, multi point fuel injection system (MPFI) is used, which can assure proper air fuel ratio to an SI engine. 164 msstevesimon@gmail.com
  165. 165. MPFI  MPFI stands for multi-point fuel injection  It allows more efficient combustion of fuel, thereby producing more power with less emissions  It is similar to CRDI in diesel engines  All modern petrol engines use MPFI systems 165 msstevesimon@gmail.com
  166. 166. MULTIPOINT INJECTION 166
  167. 167. MPFI System  MPFI does the same function as the carburettor  It has injectors which spray correct quantity of fuel for each cylinder  The fuel and air are mixed in the intake manifold before admission to the cylinder 167 msstevesimon@gmail.com
  168. 168. Components of MPFI  Electronic Control Unit (ECU)- sometimes called Engine Control Module (ECM)  High Pressure Pump Module-pump, filter, pressure regulator, common rail, sensor  Injector for each cylinder, also controlled by ECU 168 msstevesimon@gmail.com
  169. 169. 169 msstevesimon@gmail.com
  170. 170. ECU The function of ECU is to receive inputs from various sensors, compare them with pre-loaded engine and throttle parameters and send control signals to the actuators. Sensors: Sense different parameters (Temperature, Pressure, Engine Speed etc.) of the engine and send signal to ECU. Actuators: Receive control signal from ECU and actuates pump and injectors 170 msstevesimon@gmail.com
  171. 171. ECU Inputs For the Inputs, the microprocessor (or ECU) reads a number of sensors: Ambient temperature Engine RPM Coolant temperature Vehicle road speed Exhaust temperature Crankshaft position Exhaust oxygen content Camshaft position Inlet manifold vacuum Outside air pressure Throttle position Pressure on throttle Based on all these inputs from the sensors, the computer in the MPFI system decides what amount of fuel to inject, when, for what duration, and into which cylinder. It then sends signals to actuators for injection of correct quantity of fuel. 171 msstevesimon@gmail.com
  172. 172. Thus it makes the engine cleaner, more responsive, ensures complete combustion, and uses less fuel as it knows what amount of petrol should go in. Modern cars’ ECUs have memory, which will remember your driving style and will behave in a way so that you get the desired power output from engine based on your driving style. For example, if you have a habit of speedy pick-up, car’s computer will remember that and will give you more power at low engine speeds by putting extra petrol, so that you get a good pick-up. It will typically judge this by the amount of pressure you put on accelerator. 172 msstevesimon@gmail.com
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  174. 174. 174
  175. 175.  A multi-point injection system, also called port injection, has an injector in the port (air-fuel passage) going to each cylinder. Gasoline is sprayed into each intake port and toward each intake valve. Thereby, the term multipoint (more than one location) fuel injection is used. 175
  176. 176. Advantages of MPFI:  More uniform fuel-air mixture will be supplied to each cylinder. Thus the power developed by different cylinders will be more uniform.  More appropriate fuel-air mixture will be supplied, which will increase the combustion efficiency.  Cold starting can be improved.  Immediate response in case of sudden acceleration and deceleration. 176 msstevesimon@gmail.com
  177. 177. ADVANTAGES OF MPFI SYSTEMS OVER SPFI SYSTEM MPFI Better power Low power Better refinement of engines Lesser refinement of engines Better control over the process Lesser control over the process Longer life due to lesser load per injector Lesser life due to higher load Cleaning not required frequently Frequent cleaning is required No delay in response Delay in response No difference in delivery to each cylinder 177 SPFI Difference in delivery to each cylinder
  178. 178. Thank you…!! 178 msstevesimon@gmail.com

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