Automobile Engineering Lecture Notes-1 To Final Year Students By Kiranmedesign Gmail.Com
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This document provides information about automobile engineering and engine components. It discusses the basic workings of a petrol engine, classifications of engines by cylinders, arrangement, valves, cooling, cycles, and fuel type. It also describes common engine constructions like inline, V-type, and horizontally opposed engines. Key engine components are defined, including the cylinder block, cylinder head, piston, piston rings, connecting rod, crankshaft, and camshaft. Cooling systems and engine bearings are also mentioned.
Automobile Engineering Lecture Notes-1 To Final Year Students By Kiranmedesign Gmail.Com
- 1. AUTOMOBILE ENGINEERING BY KIRAN KUMAR.K Lecturer Mechanical Engineering Department College of Engineering and Technology Eritrea Institute of Technology, Mainefai, Asmara,Eritrea. e-mail: kiranmedesign@gmail.com kiranmek3@gmail.com 1
- 2. CONTENTS • Working of engine • Classification of engines • Engine construction details • Engine components • Cooling system – Air cooling system – Water cooling system Bearings 2
- 3. ENGINE 3
- 4. Petrol Engine Operation A Petrol engines operation sequence is as follows: Stroke 1 (intake) – air & fuel enter cylinder Stroke 2 (compression) – air & fuel are compressed Stroke 3 (power) – spark plug fires, ignites fuel. Stroke 4 (exhaust) – burnt gases are expelled from the engine 4
- 5. ENGINE 5
- 6. CLASSIFICATION OF ENGINES • Number of cylinders • Arrangement of cylinders – Inline, V type, Opposed piston, Opposed cylinder, Radial type • Valve arrangement – L head, T head, I head, F head • Type of cooling – Water cooling , Air cooling • Number of cycles – Two stroke, Four stroke • Type of fuel – Petrol, Diesel, LPG, CNG 6
- 7. Engine Construction 7 Inline •Here all the cylinders of the engine are in a straight line. This is the most popular type of engine in India. •The Engine is usually placed vertically or in some rarer cases kept leaning at an angle.
- 8. Engine Construction 8 V The cylinders arranged in two banks connected to the same crankshaft. Different angles are used between the cylinder banks. V engines offer the car to have more cylinders with a shorter bonnet length, giving better road visibility. V engines are well balanced, smooth and quiet in operation. Assures relatively even distribution of air fuel mixtures to all cylinders Shorter but lighter and more rigid engine
- 9. Engine Construction 9 Flat/Horizontally Opposed/Boxer A Boxer engine is a ‘V’ engine with an angle between the cylinder banks of 180 Deg. The pistons look like a boxers fists going back and forth hence the ‘boxer’ name. These engines offer some benefits, but are complicated in design and expensive to produce & maintain, hence are not widely used.
- 10. Engine Construction 10 Inline Here all the cylinders of the engine are in a straight line. This is the most popular type of engine in India. The Engine is usually placed vertically or in some rarer cases kept leaning at an angle. V The cylinders arranged in two banks connected to the same crankshaft. Different angles are used between the cylinder banks. V engines offer the car to have more cylinders with a shorter bonnet length, giving better road visibility. V engines are well balanced, smooth and quiet in operation. Flat/Horizontally Opposed/Boxer A Boxer engine is a ‘V’ engine with an angle between the cylinder banks of 180 Deg. The pistons look like a boxers fists going back and forth hence the ‘boxer’ name. These engines offer some benefits, but are complicated in design and expensive to produce & maintain, hence are not widely used.
- 11. CLASSIFICATION OF ENGINES • Number of cylinders • Arrangement of cylinders – Inline, V type, Opposed piston, Opposed cylinder, Radial type • Valve arrangement – L head, T head, I head, F head • Type of cooling – Water cooling , Air cooling • Number of cycles – Two stroke, Four stroke • Type of fuel – Petrol, Diesel, LPG, CNG 11
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- 13. CLASSIFICATION OF ENGINES • Number of cylinders • Arrangement of cylinders – Inline, V type, Opposed piston, Opposed cylinder, Radial type • Valve arrangement – L head, T head, I head, F head • Type of cooling – Water cooling , Air cooling • Number of cycles – Two stroke, Four stroke • Type of fuel – Petrol, Diesel, LPG, CNG 13
- 14. ENGINE – CONSTRUCTIONAL DETAILS • Cylinder block • Cylinder head • Piston • Piston rings • Piston pins • Connecting rod Fig • Crank shaft • Cam shaft • Cam ,Push rod • Valves • Fly wheel 14
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- 16. SWIFT DIESEL 16
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- 18. CYLINDER BLOCK • Basic frame work of an engine. • Material : Alu i iu , Gray cast iro or iro alloyed ith Ni, Cr… • Block contains cylinder, water jackets, water pump, timing gear, ignition distributor, valves, fuel pump etc • Cylinder contains bore liners (iron or steel alloy with good wear resistant) • Dry liners - Contributes to rigidity ,less heat transfer • Wet liners - Less rigid, Easy to remove, More heat transfer, Coolant leakage • 18
- 19. Engine Cylinder Block • The engine cylinder block is the basic frame of a liquid-cooled engine, whether it is the in-line, horizontally opposed, or V-type. • The cylinder block and crankcase are often cast in one piece that is the heaviest single piece of metal in the engine. • In small engines, where weight is an important consideration, the crankcase may be cast separately. • In most large diesel engines, such as those used in power plants, the crankcase is cast separately and is attached to a heavy stationary engine base. • In practically all automotive and construction equipment, the cylinder block and crankcase are cast in one piece. • The cylinders of a liquid-cooled engine are surrounded by jackets through which the cooling liquid circulates. These jackets are cast integrally with the cylinder block. • The cylinders of air-cooled engines have closely spaced fins surrounding the barrel; these fins provide an increased surface area from which heat can be dissipated. • This engine design is in contrast to that of the liquid-cooled engine, which has a water jacket around its cylinders. 19
- 20. Cylinder Block Construction • The cylinder block is cast from gray iron or iron alloyed with other metals such as nickel, chromium, or molybdenum or aluminum. • Cylinders are machined by grinding or boring to give them the desired true inner surface. During normal engine operation, cylinder walls will wear out-of-round, or they may become cracked and scored if not properly lubricated or cooled. • Liners (sleeves) made of metal alloys resistant to wear are used in many gasoline engines and practically all diesel engines to lessen wear. • The liners are inserted into a hole in the block with either a PRESS FIT or a SLIP FIT. Liners are further designated as either a WET-TYPE or DRY-TYPE. The wet-type liner comes in direct contact with the coolant and is sealed at the top by a metallic sealing ring and at the bottom by a rubber sealing ring. The dry-type liner does not contact the coolant. • Engine blocks for L-head engines contain the passageways for the valves and valve ports. The lower part of the block (crankcase) supports the crankshaft (the main bearings and bearing caps) and provides a place to which the oil pan can be fastened. • The camshaft is supported in the cylinder block by bushings that fit into machined holes in the block. On L-head in-line engines, the intake and exhaust manifolds are attached to the side of the cylinder block. On L-head V-8 engines, the intake manifold is located between the two banks of cylinders; these engines have two exhaust manifolds, one on the outside of each bank. 20
- 21. CYLINDER HEAD • Separate casting bolted to the top of the cylinder block • Contains the combustion chambers, spark plug, valves, water jackets • Material :Gray iron or Aluminium alloy GASKET • Joint between cylinder block an cylinder head • Material :Thin sheets of soft metal or of asbestos and metal • Squeezes the soft metal thus sealing effectively 21
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- 23. CRANK CASE • Base of the engine • Supports the crank shaft and cam shaft • Top half of the crank case is the integral part of cylinder block • Bottom half of the crank case – Oil pan (Pressed steel or Aluminium) • Material : Ferrous alloy or semi steel • 23
- 24. • The crankcase also has mounting brackets that support the entire engine on the vehicle frame. • These brackets are either an integral part of the crankcase or are bolted to it so that they support the engine at three or four points. • These points of contact usually are cushioned with rubber that insulates the frame and the body of the vehicle from engine vibration and therefore prevents damage to the engine supports and the transmission. 24
- 25. PISTON • Acts as a cylindrical plug • Functions: – To create vacuum – To compress air fuel mixture – To transmit the power – To expel the exhaust products • Material – Aluminium, Cast iron. – Chrome Nickel • Head, skirt, land, grooves • Piston bosses – Reinforced sections of the piston designed to hold the piston pin • Piston clearance (0.001 – 0.002 inches) – Small clearance - Piston seizure, oil film – Large clearance - Piston slap, blow by – Depends upon (1) Bore of the cylinder (2) Material 25
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- 28. PI“TON RING“….. • To prevent blow by. • Compression rings - To maintain cylinder pressures • Oil control rings - Scrape the excess oil from the cylinder • Material : Cast iron • Compression rings – Figure • • Figure of joints • Diameter of rings are slightly larger than the bore • Staggered joints 28
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- 30. PI“TON RING“ ….. • Compression rings – Action during suction and compression – Coati gs aterials such as graphite, phospate for effecti e ear i – Soak up oil – improve ring lubrication –prevent scuffing • Oil control rings –- Prevents excess of oil going into combustion chamber – functions of oil – Effect of speed on oil control 30
- 31. RING EXPANDER 31 • Steel spring in the shape of a wavy or humped ring • Ring expander makes up for any loss of tension from the reduced thickness
- 32. PISTON • Methods of keeping piston from excessive dimensional change – Use of special alloy- steel struts or rings – Horizontal and vertical slots (Fig) – Heat dams (Fig) – Cam ground pistons (Fig) 32
- 33. CONNECTING ROD • Should be stronger, rigid , lighter (to minimize vibration). • I section • Careful matching of rods and cap to maintain good engine balance, equal weight • Lubrication • Babbitt bearings • Bearing linings of steel backed copper lead or steel backed cadmium silver • 1 - Cap bolt nut lock washer • 2 - Cap –bolt nut • 3 - Cap • 4 - Rod bearings • 5 - Tongue and groove • 6 - Cap bolt • 7 - Piston pin bearing • 8 - Oil holes • 9 - Oil hole • 10 - Assembled rod 33
- 34. METHODS OF ATTACHING THE ROD AND PISTON • Locking the pin to the piston with lock bolt (Fig) • Locking the connecting rod to piston pin by clamp screw (Fig) • Lock rings (Fig) 34
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- 38. CRANK SHAFT • Converts the reciprocating motion to the rotary motion. • Made from steel forging or casting, Stronger • Length of crank arm decides the stroke • Drilled oil passages for the flow of oil to the connecting rod brg. • 38
- 39. CRANK “HAFT……… •Counter Weights - To balance – Centrifugal force – Inertia force • Heavy bending moment without the counter weights • Speed up and slow down of crankshaft - Flywheel. 39
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- 41. VALVE“, CAM “HAFT, PU“H ROD ……. 41
- 43. 43 L and T type heads
- 44. Engine- No. of Valves 44 Valve: Valves are provided in the engine to “breathe” (to take in air and to let out exhaust gases). Minimum no of valves required per cylinder are 2 (one for inlet and one for exhaust). Most Maruti Vehicles have 4 Valves per cylinder which is Most Advanced Technology. VALVE
- 45. 45 • Material : • Exhaust: Silichrome (unusual resistance to heat) • Inlet : Nickel – chromium alloy • Valve tappet clearance (valve lash) • Valve cooling : • Importance of valve seating • Sodium cooled valves
- 46. 46 • Silent lash rocker arm (Eccentric rocker arm)- I type
- 47. Engine- No. of Valves 47 Advantage: More no of valves per cylinder allow the engine to breathe easily. Benefits : • Higher Power • Lesser Pollution 2 valves 3 valves 4 valves Technology Old New Latest Power Developed Less More Most Fuel Economy Less More Most Emissions Most More Less
- 48. Models – Valve Arrangements 48 2 valves 3 valves 4 valves Ikon Santro XL-7 Grand Vitara Palio 1.2 Accent 1.5 Gypsy Petra Diesel Lancer Zen Getz Esteem Baleno WagonR Accent 1.6 Camry Indica Xeta
- 49. Single Over Head Camshaft (SOHC) In SOHC system all inlet and exhaust valves are operated by one camshaft which is located in the cylinder head (Top part of engine) . This type of arrangement is used in conventional cars and is superior to the older arrangement which had push rods to operate the valves. 49
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- 51. Engine- Power (BHP) Brake Horse Power (BHP) is the British unit of measuring power, developed by an engine. Power is a measure of how quickly work can be done (moving the car) Power (BHP) of the engine depends on its torque and engine speed (RPM), more the torque or more the rpm, greater is the BHP 51 CC : It represents the size of Engine (Combustion Chamber) E.g. Size of WagonR engine is 1061 cc, 1061 cubic centimeters. Widest range of engine sizes from 800cc to 2700cc Engine - Size
- 52. P-S •PS is a German term for Metric Horse Power a different unit of measurement of power developed by the engine. •1 Metric hp = 1 PS = 0.986 bhp •100 PS is equivalent to 98.6 bhp. •In Indian Market all the manufacturers use unit of PS or Metric Horsepower to indicate engine power. 52
- 53. Engine- Power to Weight Ratio (PWR) 53 Having more power only is not effective as one must also see the weight that the power has to carry. Thus the power to weight ratio must be observed. Power to Weight Ratio (PWR) : Power to weight ratio (PWR) is the ratio of bhp (power) to the weight of the vehicle in tons. PWR = bhp/ Weight of car in tons. Higher PWR indicates vehicle’s capability to pull more weight and accelerate quickly (better pick-up).
- 54. Comparison of Torque, BHP & PWR (e.g. WagonR) 54 TORQUE BHP PWR Example 84 N.m@3500 rpm 64 bhp @6200 rpm 77.57 Vehicle 84 N.m indicates maximum torque developed 64 bhp indicates the maximum bhp developed 77.57 indicates the pick-up or acceleration of the vehicle. RPM The rpm indicates the speed of the engine at which maximum torque is developed The rpm indicates the speed of the engine at which maximum power is developed —
- 55. BEARINGS • Bearing = Any thing that supports load • For supporting and controlling the motion of rotating, sliding or reciprocating parts • Minimize friction, loss of power, heat generation (with the aid of lubrication) • Types of Friction – Dry friction : Resistance to relative motion between two dry objects – Greasy friction : Friction between two solids coated with a thin film of oil – Viscous friction: Resistance to relative motion between adjacent layers of liquid. • Types of bearings – Radial bearing – Load perpendicular to the axis of the shaft – Thrust bearing - Load parallel to the axis of the shaft – Radial Thrust bearing – Load parallel and perpendicular to the axis of the shaft – Slipper bearing (Guide) - Limit the motion to a straight line 55
- 56. 56 Radial bearing (Plain) Thrust bearing Radial thrust bearing
- 57. BEARING “URFACE“ IN AUTOMOBILE“…. 57
- 58. BEARING“ IN AUTOMOBILE“…. • Plain bearing - Friction bearing • Ball bearing - Anti friction bearing • Roller bearing - Anti friction bearing Plain bearing (Radial bearing) – high loads • Made of dissimilar metals • Lining of low friction material • Bearing crush 58
- 59. 59 • Bearing oil clearance • About 0.00015 inch – varies with engines • Optimum oil clearance • Excessive clearance – high oil consumption, oil starvation • Less clearance -- Metal to metal contact •Bearing assembly • Clean • Free of burrs • Centralize the cap and bearing
- 60. BEARING“ IN AUTOMOBILE“…. Ball bearing • Anti friction bearing • Substitutes rolling for sliding friction • Radial thrust ball bearing (Angular contact) (Fig) • Bearing number • Needs occasional lubrication to facilitate sliding and protect highly polished surfaces 60
- 61. BEARING“ IN AUTOMOBILE“…. Roller bearing • Straight roller bearing – Square roller bearing – Journal roller type – Needle bearing • Tapered roller bearing 61
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- 64. LUBRICATION OF BEARINGS • To protect the highly finished parts from rust and corrosion • To reduce bearing temperature • Keep out the foreign matters • Lubricant depends upon the operating condition and the location • • BEARING REQUIREMENTS • Load carrying capacity • Fatique resistance • Embadability • Corrosion resistance • Low wear rate 64
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- 67. COOLING SYSTEM Purpose of cooling • To keep the engine at its most efficient operating temperature at all driving condition • To prevent the deterioration of the lubricating oil (160°C – 200°C) • Decrease in the strength of the material (270°C) • Results in excessive thermal stresses resulting in cracking • Hot spot leading to pre ignition and detonation • Reduction of the volumetric efficiency an hence power Over cooling problems ????? • Starting problem • High corrosion. To avoid condensation of acid, coolant temperature should be more than 70°C. 67
- 68. AIR COOLING • Heat transfer by convection • Fins to enhance the heat transfer • Heavily thermal stressed parts should be finned • Air cooling results in higher temperature and hence larger clearance • Height of fins control the spacing between the cylinders • Types of fins – Length of the fins – Spacing between the fins 68
- 69. AIR COOLING….. Advantages • No ater jacker,pu p… - Weight reduction –Small size • Simpler engine design • Less sensitive to climatic condition • Better warm up performance • Reduced carbon deposits due to higher Temperature • Easier control • Can take up some degree of damage Disadvantages • Combustion noise is not attenuated • Lower volumetric efficiency • High specific output engines can not be air cooled 69
- 70. Advantages • Can be used for high sp. Output engine as h of water is high (350 times air) • High latent heat of water avoids hot spots • Combustion noise is attenuated • High volumetric efficiency • Engine can be installed anywhere • Disadvantages • Increase in the weight • Increase in frontal area increases air resistance • Requires more maintenance • Sensitive to climatic condition –Ethylene glycol & Water solution _ Deposits • Power absorption by the water pump • Poor warm up performance- greater wear 70
- 71. TYPE OF COOLING SYSTEM • Thermosyphon cooling • Forced cooling system • Cooling with thermostat regulator • Pressurized water cooling 71
- 72. THERMOSYPHON COOLING • Cooling depends only on temperature and independent of speed • Circulation starts only after engine becomes hot • Accumulation of scales 72
- 73. FORCED OR PUMP COOLING SYSTEM • Cooling is ensured under all conditions of operations • Circulation stops when engine stops • Cooling depends of speed – independent of temperature • Overheating & over cooling –Thermostatic device 73
- 74. THERMOSTAT COOLING • Engine warm up quickly after starting • No method to increase the cooling action 74
- 75. THERMOSTAT 75 THERMOSTAT WITH DISC VALVE RADIATOR AND BY PASS FLOW CONTROL
- 76. TWO STAGE THERMOSTAT CONTROL 76
- 77. WATER JACKET, WATER PUMP • Centrifugal pump • Nonpositive pump 77
- 78. FAN • To provide powerful draft of air through the radiator to improve engine cooling. • Need for fan drive control?? – Excessive cooling – Vibration – Absorption of power 78
- 79. ELECTRIC MOTOR DRIVEN THERMOSWITCH CONTROLLED FAN 79
- 80. MECHANICAL CRANK PIN VARIABLE PITCH TEMPERATURE SENSITIVE FAN DRIVE 80
- 81. PRESSURIZED COOLING SYSTEM • The boiling point of the coolant is increased by increasing its pressure. • Radiator cap • Blow off valve and vacuum valve 81
- 82. RADIATOR • To hold large volume of water in close contact with large volume of air to enhance the heat transfer. – Increasing the coolant flow rate raises the power required to drive the pump- offset the increase in the effectiveness – Increasing the mean temperature difference between coolant and air raises the heat dissipation capacity – Increasing the cooling systems operating pressure raises the boiling point of the coolant – 50 % ethylene glycol reduces the heat dissipation capacity by around (15%) 82
- 84. RADIATOR CORE 84 • Tube and fin type • Ribbon – cellular type
- 85. TEMPERATURE INDICATORS • Vapour pressure – Bourdon tube pressure gauge • Electric indicators – Bi metal thermostat type – Balancing coil type 85
- 86. – Indicator unit (Bourdon tube ) – Indicator bulb 86
- 87. • Electric indicators – Bi metal thermostat type – Balancing coil type 87