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# 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
161. 161. 161
162. 162. Components of GDI engine  Pumping element  Metering element  Mixing element  Mixture control  Distributing element  Ambient control 162 msstevesimon@gmail.com
163. 163. 163
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
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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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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