Introduction to internal combustion engine.pptx

internal combustion engine in automobile engineering

1. Introduction to internal combustion engine Heat engines A heat engine is a device that converts thermal energy into mechanical work or electrical energy. It works by harnessing the energy released from a heat source, such as burning fuel or a nuclear reaction, and using it to generate motion or electricity.

2. External combustion engine An external combustion engine is a type of heat engine where the combustion of fuel takes place outside the engine itself. This is in contrast to internal combustion engines, where the combustion of fuel occurs within the engine.In an external combustion engine, the fuel is burned in a separate chamber or furnace, and the heat produced is transferred to the engine via a working fluid, such as steam or gas. This working fluid is then expanded in the engine, producing mechanical work or electricity.

3. Internal combustion engine An internal combustion engine (ICE) is a type of heat engine where the combustion of fuel occurs within the engine itself. This is in contrast to external combustion engines, where the combustion of fuel occurs outside the engine.In an internal combustion engine, a mixture of fuel and air is ignited inside a combustion chamber, generating a high-temperature and high-pressure gas that expands and produces mechanical work. This mechanical work is then converted into rotational energy, which powers a vehicle or other machine.

4. The key components of an internal combustion engine include: 1. Cylinders: These are the chambers where the fuel-air mixture is ignited. 2. Pistons: These move up and down in the cylinders, driven by the explosive force of the combustion process. 3. Crankshaft: This converts the up-and-down motion of the pistons into rotational energy. 4. Camshaft: This operates the valves that allow air and fuel into the cylinders and exhaust gases out. 5. Valves: These control the flow of air and fuel into the cylinders and exhaust gases out.

5. Development of IC engines - First Patent: In 1791, the English inventor John Barber patented a gas turbine ¹.- First Gas Engine: In 1794, Thomas Mead patented a gas engine, and Robert Street patented an internal-combustion engine, which also used liquid fuel ¹.- First American Engine: In 1798, John Stevens designed the first American internal combustion engine ¹.- First Car: In 1807, the Swiss engineer François Isaac de Rivaz built and patented a hydrogen and oxygen-powered internal-combustion engine and fitted it to a crude four-wheeled wagon ¹.- First Industrial Engine: In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially in the United States ¹. - First Real Engine: In 1853, Father Eugenio Barsanti , an Italian engineer, and Felice Matteucci of Florence invented the first real internal combustion engine ¹.- First Commercial Engine: In 1864, Nicolaus Otto patented the first commercially successful gas engine ¹.- First Liquid- Fueled Engine: In 1872, George Brayton invented the first commercial liquid- fueled internal combustion engine ¹ .- First Four-Stroke Engine: In 1876, Nicolaus Otto, working with Gottlieb Daimler and Wilhelm Maybach , patented the compressed charge, four-stroke cycle engine ¹.- First Diesel Engine: In 1892, Rudolf Diesel developed the first compressed charge, compression ignition engine ¹ .- First Pistonless Engine: In 1954, German engineer Felix Wankel patented a " pistonless " engine using an eccentric rotary design ¹.

6. Classification of IC engines Internal combustion (IC) engines can be classified in various ways based on different criteria. Here are some common classifications :1. Type of Fuel: - Gasoline engines - Diesel engines - Natural gas engines - Hybrid engines (combination of two or more fuels) 2. Cycle: - Two-stroke engines - Four-stroke engines - Six-stroke engines 3. Number of Cylinders: - Single-cylinder engines - Multi-cylinder engines (inline, V-type, boxer, etc.

7. 4. Valve Configuration: - Overhead valve (OHV) engines - Overhead camshaft (OHC) engines - Single overhead camshaft (SOHC) engines - Double overhead camshaft (DOHC) engines 5. Ignition System: - Spark ignition (SI) engines - Compression ignition (CI) engines 6. Cooling System: - Air-cooled engines - Liquid-cooled engines 7. Engine Layout: - Inline engines - V-type engines - Boxer engines - Rotary engines ( Wankel engines)

8. 8. Supercharging/ Turbocharging : - Naturally aspirated engines - Supercharged engines - Turbocharged engines 9. Emissions: - Conventional engines (non-emission controlled) - Emission-controlled engines (e.g., catalytic converter, EGR) 10. Hybrid/Electric: - Hybrid electric engines - Plug-in hybrid engines - Electric engines (non-IC engines) These classifications can be combined to describe a specific engine configuration, such as a "4-cylinder, 4-stroke, gasoline, DOHC, turbocharged engine".

9. application Internal Combustion (IC) engines have numerous applications in various fields, including: 1. Transportation: - Automobiles (cars, trucks, buses) - Motorcycles - Airplanes (aircraft engines) - Ships and boats (marine engines) 2. Power Generation: - Electric generators (backup power, remote areas) - Portable generators (construction, events) 3. Industrial Applications: - Compressors (air, gas, refrigeration) - Pumps (water, oil, chemicals) - Conveyor systems - Industrial machinery (e.g., cranes, forklifts) 4. Agricultural Applications: - Tractors - Combine harvesters - Plows - Irrigation pumps

10. 5. Construction Equipment: - Cranes - Excavators - Bulldozers - Road rollers 6. Small Engines: - Lawn mowers - Chain saws - Leaf blowers - Generators (small portable) 7. Aerial Applications: - Drones (unmanned aerial vehicles) - Model airplanes 8. Marine Applications: - Outboard motors - Inboard engines - Stern drive engines

11. 9. Emergency Equipment: - Fire pumps - Ambulance engines - Emergency generator sets 10. Recreational Applications: - Motorboats - Personal watercraft (Jet Skis) - Snowmobiles - All-terrain vehicles (ATVs)

12. Engine cycle energy balance 1. Input Energy: - Chemical energy in the fuel (e.g., gasoline, diesel) - Thermal energy from combustion 2. Useful Work: - Mechanical energy converted to rotational energy (torque) - Power output (e.g., propelling a vehicle, generating electricity) 3. Energy Losses: - Heat Transfer: - Cooling system (e.g., radiator, coolant) - Exhaust system (e.g., muffler, tailpipe)

13. - Friction: - Mechanical friction (e.g., piston rings, cylinder walls) - Viscous friction (e.g., engine oil, air resistance) - Combustion Losses: - Incomplete combustion - Heat loss to the combustion chamber walls

14. 4. Engine Efficiency: - Thermal efficiency ( ηth ): ratio of useful work to input energy - Indicated efficiency ( ηi ): ratio of indicated work (work done on the piston) to input energy - Brake efficiency ( ηb ): ratio of brake work (work done on the crankshaft) to input energy Understanding the engine cycle energy balance is crucial for Improving engine efficiency 2. Reducing emissions 3. Optimizing engine performance 4. Developing new engine technologies

15. Basic idea of IC engines 1. Air and Fuel Intake: Air and fuel are drawn into a cylinder through an intake valve. 2. Compression: The air-fuel mixture is compressed by a piston, creating a small explosion chamber. 3. Ignition: A spark plug (in gasoline engines) or fuel injection (in diesel engines) ignites the compressed air-fuel mixture, causing a small explosion. 4. Power Stroke: The explosion forces the piston down, rotating the crankshaft and converting the chemical energy into mechanical energy. 5. Exhaust: The piston pushes the exhaust gases out of the cylinder through an exhaust valve.

16. Key components: - Cylinders- Pistons - Crankshaft- Camshaft - Valves (intake and exhaust) - Spark plugs (gasoline engines) or fuel injectors (diesel engines)

17. Different components of IC engines. 1. Cylinders: Fuel is burned inside the cylinders to produce power. 2. Pistons: Move up and down in the cylinders, driven by the explosive force of the fuel. 3. Crankshaft: Converts the up-and-down motion of the pistons into rotational energy. 4. Camshaft: Operates the valves that allow air and fuel into the cylinders and exhaust gases out.

18. 5. Valves: Control the flow of air and fuel into the cylinders and exhaust gases out. 6. Flywheel: Smooth out the power strokes and provides a mechanical advantage. 7. Engine Block: The main housing for the engine's components. 8. Cylinder Head: Sits on top of the engine block and contains the valves. 9. Spark Plugs (Gasoline engines) / Fuel Injectors (Diesel engines): Ignite the fuel-air mixture.

19. 10. Timing Belt (or Chain): Synchronizes the rotation of the crankshaft and camshaft .11. Oil Pump: Circulates engine oil to lubricate the moving parts. 12. Water Pump: Regulates engine temperature by circulating coolant. 13. Exhaust System: Directs exhaust gases away from the engine. 14. Intake Manifold: Directs air and fuel into the cylinders. 15. Fuel System: Delivers fuel to the cylinders.

20. crank Crank: A crank is a rod or shaft that converts the up-and-down motion of the pistons into rotational energy, ultimately powering the vehicle. It's a key component that transforms the reciprocating motion of the pistons into a rotating motion, which is then transferred to the transmission and eventually turns the wheels.

21. Gudgeon pin A gudgeon pin is a small, cylindrical pin that connects the piston to the connecting rod, allowing the piston to move up and down in the cylinder while transferring the force of the explosion to the crankshaft. It's a vital component that plays a key role in converting the reciprocating motion of the piston into rotational energy.

22. cam cam:- A cam is a rod or shaft with an irregular shape, typically a lobed or eccentric shape, that is used to convert rotational motion into linear motion or vice versa.- In an internal combustion engine, the cam is used to operate the valves that allow air and fuel into the cylinders and exhaust gases out.- The cam is driven by the crankshaft and rotates in sync with the engine's rotation.

23. Rocker Arm:- A rocker arm is a lever that pivots on a fulcrum and is used to transfer motion from the cam to the valve stem, opening and closing the valves.- The rocker arm is typically pivoted in the middle and has a cam lobe on one end and a valve stem on the other.- As the cam rotates, it pushes the rocker arm, which then opens and closes the valve, allowing air and fuel into the cylinder or exhaust gases out.

24. Engine bearing Engine Bearing:- An engine bearing is a critical component that supports the moving parts of an internal combustion engine, such as the crankshaft, camshaft, and connecting rods.- Engine bearings are typically made of a durable material, like bronze, aluminum , or steel, and are designed to withstand high loads, friction, and heat.- Their primary function is to: 1. Support the moving parts, allowing them to rotate or move smoothly. 2. Reduce friction 3. Absorb shock loads and vibrations, ensuring smooth engine operation.

25. Terms connected with IC engines 1. Bore: The diameter of the cylinder. 2. Stroke: The distance the piston travels up and down in the cylinder. 3. Compression ratio: The ratio of the cylinder volume when the piston is at the bottom to the volume when the piston is at the top. 4. Cylinder head: Sits on top of the engine block and contains the valves. 5. Engine block: The main housing for the engine's components.

26. 6. Piston ring: Seals the gap between the piston and the cylinder wall. 7. Cranksshaft position sensor: Monitors the rotation and position of the crankshaft .8. Camshaft: Operates the valves that allow air and fuel into the cylinders and exhaust gases out. 9. Valves: Control the flow of air and fuel into the cylinders and exhaust gases out. 10. Fuel injector: Sprays fuel into the cylinders. 11. Spark plug: Ignites the fuel-air mixture in gasoline engines.

27. 12. Timing belt or chain: Synchronizes the rotation of the crankshaft and camshaft. 13. Oil pump: Circulates engine oil to lubricate the moving parts. 14. Water pump: Regulates engine temperature by circulating coolant. 15. Exhaust manifold: Directs exhaust gases away from the engine. 16. Intake manifold: Directs air and fuel into the cylinders.

28. 17. Fuel system: Delivers fuel to the cylinders. 18. Ignition system: Generates the spark or heat to ignite the fuel-air mixture. 19. Engine management system: Computer that controls the engine's operation. 20. Torque: Rotational force that propels the vehicle forward.

29. Clearance volume it is the volume of the cylinder between the piston and the cylinder head when the piston is at the top of its stroke. It's the space left between the piston and the cylinder head when the piston is at its highest point. Clearance Volume = Cylinder Volume - Displacement Volume

30. Top Dead Centre refers to the position of the piston in a cylinder when it is at its highest point, i.e., when the piston is at the top of its compression stroke or power stroke.

31. Bottom Dead Centre refers to the position of the piston in a cylinder when it is at the very bottom of its stroke, i.e., when the piston is at its lowest point in the cylinder. This position is also known as the "bottom of the stroke".

32. Swept volume, also known as displacement volume, is the volume of the cylinder that is swept by the piston as it moves from Top Dead Centre (TDC) to Bottom Dead Centre (BDC). It's the amount of air-fuel mixture that is drawn into the cylinder during the intake stroke.

33. Piston speed, also known as piston velocity, is the speed at which the piston moves up and down in the cylinder. It's a vital factor in determining engine performance, efficiency, and durability.Piston speed is typically measured in meters per second (m/s) or feet per second (ft/s). It's calculated using the following formula :Piston Speed = 2 × Stroke × RPM / 60

34. Indicator diagram 1. Suction Stroke (Intake Stroke)- The piston moves downwards, creating a vacuum in the cylinder.- Air-fuel mixture is drawn into the cylinder through the intake valve.- The intake valve is open, and the exhaust valve is closed.

35. Compression Stroke- The intake valve closes, and the piston moves upwards, compressing the air-fuel mixture.- The compression ratio (CR) is the ratio of the cylinder volume to the combustion chamber volume.- The air-fuel mixture is compressed, preparing it for ignition.

36. Expansion Stroke (Power Stroke)- The spark plug ignites the compressed air-fuel mixture, causing a small explosion.- The piston moves downwards, rotating the crankshaft and generating power.- The expansion stroke is where the engine produces its power.

37. Exhaust Stroke- The piston moves upwards, pushing exhaust gases out of the cylinder through the exhaust valve.- The exhaust valve is open, and the intake valve is closed.- The exhaust gases are released into the atmosphere, and the cycle repeats.

38. Four stroke cycle engines and valve timing diagram(petrol) A Spark Ignition (SI) engine is a type of internal combustion engine that uses a spark plug to ignite a mixture of air and fuel in the engine's cylinders.

39. Theoretical four stroke Otto cycle engine 1. Suction stroke:- during this stroke also known as induction stroke the piston moves from TDC to BDC the inlet valve open and proportionate air fuel mixture is sucked in the engine cylinder. This operation is represented by the line 5-1. the exhaust valve remain closed throughout the stroke

40. Compression stroke In this stroke the piston moves 1-2 towards TDC and compresses the enclosed air fuel mixture drawn in the engine cylinder during suction stroke. The pressure of the mixture rises in the engine cylinder to a value of about 8 bar. Just before the end of this stroke the spark plug initiates a spark which ignites the mixture and combustion take place at constant volume line 2-3. both the inlet and exhaust remain closed during the stroke.

41. Expansion or working stroke When the mixture is ignited by the spark plug the hot gasses are produced which drive or throw the piston from TDC to BDC and thus the work is obtained in this stroke. It is during this stroke that we get power from the engine. The other three stroke namely suction compression and exhaust being idle. The flywheel mounted on the engine shaft stores energy during this stroke and supplies it during the idle stroke. Both the valve remain closed during the start of this stroke but when the piston just reaches the BDC the exhaust valve open.

42. Exhaust stroke This is the last stroke of the cycle. Here the gasses from which the work has been collected become useless after the completion of expansion stroke and are made to escape through exhaust valve to the atmosphere. This removal of gas is accomplished during this stroke. Piston moves from BDC to TDC. And the exhaust gasses are driven out of the engine cylinder. This is also called scavenging. The process is represented by the line 1-5.

43. Line 5-1 is below the atmospheric pressure line. The loop which has area 4-5-1 is called the negative loop. It gives the pimping loss due to admission of air fuel mixture and removal of exhaust gasses. The area 1-2-3-4- is called the total gross work obtained from the piston and net work can be obtained by subtracting area 451 from the area 1234.

44. 5

45. Valve timing diagram (theoretical)

46. Suction/Intake stroke In a four-stroke cycle petrol engine during suction stroke, the air-fuel mixture is introduced to the combustion chamber. The piston moves from TDC (Top Dead Center ) to the BDC (Bottom Dead Center ). TDC is the farthest position of the piston, and BDC is the nearest position of the piston to the crankshaft. As the piston moves toward the BDC, it creates a low-pressure area in the cylinder. The intake valve remains open up to a few degrees of crankshaft rotation after BDC, and as the intake valve closes, it seals the air-fuel mixture in the cylinder. During suction, the inlet valve remains open, the outlet valve remains closed, and the crankshaft rotates to 180 degrees.

47. Compression Stroke The air-fuel mixture trapped during suction is compressed inside the cylinder during the compression stroke. The piston moves from BDC to TDC to compress the air-fuel mixture; the piston moves forward with the help of flywheel momentum. On compressing the air-fuel mixture, more energy is released on charge ignition. The charge is the volume of compact air-fuel mixture sealed in the combustion chamber, ready for ignition. During compression, both inlet and outlet valves remain closed, and the crankshaft rotates to 180 degrees more. Now, the total rotation of the crankshaft is 360 degrees.

48. Combustion Stroke It is also called a power stroke. After the compression, the crankshaft completes one full rotation, and its second rotation begins. When the compressed air-fuel mixture is kindled with the help of a spark plug, the power stroke occurs. Combustion is a rapid process, and the oxidized  chemical reaction  (presence of oxygen in the atmosphere) releases heat energy. The hot expanding gasses force the piston away from the head of the cylinder. During combustion, both inlet and outlet valves remain closed, and the crankshaft rotates to 180 degrees more. Now, the total rotation of the crankshaft is 540 degrees. During the power stroke, as the piston reaches the BDC, the cylinder is filled with exhaust gasses, and the combustion is completed.

49. Exhaust Stroke During the exhaust stroke, the exhaust valve opens, and the inertia of the flywheel and other moving parts pushes the piston back to the TDC and allows the exhaust gasses through the open valve. The position of the piston is at TDC. So, at the end of the exhaust stroke, one operating cycle of the engine has been completed. During exhaust, the inlet valve remains closed, the outlet valve remains open, and the crankshaft rotates to 180 degrees. Now, the total rotation of the crankshaft is 720 degrees.

50. Two stroke cycle engine

51. working The piston moves from TDC to BDC at a crank angle of 120 During the expansion stroke the exhaust port opens 60 before BDC and closes at 60 after BDC and burnt gasses starts to escape from the cylinder. The transfer port opens 45 before BDC and closes at 45 after BDC during this process fresh air enters the cylinder. There will be 90 overlapping of ports which is called scavenging process and the fresh charge of air will force the burnt gasses to completely escape from the combustion chamber. Compression stroke starts at 120 before TDC. The spark ignite at 10 before TDC. During the compression stroke 50 before TDC The reed valve opens and the inlet port is also open and fresh charge of air enters the crankcase till 50 after TDC during expansion stroke. the cycle continuous.

52. IPC

53. 4 stroke petrol engine valve timing diagram actual

54. During the suction stroke of a 4-stroke engine, the inlet valve opens approximately 10-20 degrees in advance before the top dead center (TDC). This timing allows for proper intake of air-fuel mixture, while also facilitating the cleansing of any remaining combustion residuals within the combustion chamber. During this stroke the inlet valve is open and exhaust valve is closed. The compression stroke begins after 30 degree after BDC. The piston then starts moving towards TDC, and during this compression stroke, the inlet valve closes approximately 25-30 degrees past BDC. This closure ensures complete sealing of the combustion chamber, enabling effective compression of the air-fuel mixture Within the compression stroke, as the piston progresses towards TDC, the spark ignites 35 degree before TDC. This timing ensures proper fuel combustion and the optimal propagation of the flame.

55. Following combustion, the expansion stroke commences. it starts 35 degree before TDC and ends at 50 degree before BDC. This stroke is initiated by the release of pressure inside the combustion chamber due to the fuel combustion, resulting in the rotation of the crankshaft. The piston moves from TDC to BDC during the expansion stroke, spanning approximately 30-50 degrees before BDC. Both the valves are closed in this stroke. To begin the exhaust stroke, the exhaust valve opens approximately 30-50 degrees before BDC. This enables the expulsion of combustion residuals as the piston moves from BDC to TDC. The exhaust stroke continues until roughly 10-20 degrees of crank after the piston reaches TDC. The exhaust valve is open and inlet valve is closed in this stroke.

56. How to tell a two stroke engine from four stroke engine Number of Strokes:  The main difference between a two-stroke engine and a four-stroke engine is the number of strokes needed to complete a full cycle. In a two-stroke engine, the piston completes a power cycle (intake, compression, power, and exhaust) in just two strokes - one upstroke and one down stroke. In a four-stroke engine, the piston completes the same cycle in four strokes - intake, compression, power, and exhaust. Combustion Process:  In a two-stroke engine, the combustion of the fuel-air mixture occurs every revolution of the crankshaft, while in a four-stroke engine, combustion happens every other revolution. Oil and Fuel Mixing:  Two-stroke engines require oil to be mixed with the fuel to lubricate the engine components, whereas four-stroke engines have a separate oil reservoir and do not require oil to be mixed with the fuel.

57. Simplicity:  Two-stroke engines are generally simpler in design compared to four-stroke engines due to their fewer moving parts and lighter weight. Exhaust:  Two-stroke engines typically have a more noticeable and smokier exhaust due to the oil mixed with the fuel burning in the combustion process. Sound:  Two-stroke engines often have a higher-pitched sound compared to the deeper sound of four-stroke engines.