Principles and Working of I.c. engine.pptx

In this slide we will study in detail about the working principles of I.C. engine.

1. Principles and Working of I.C. Engine Principle A mixture of fuel with correct amount of air is exploded in an engine cylinder which is closed at one end. As a result of the explosion , heat is released and this causes the pressure of the burning gases to increase. This pressure increase, forces a close fitting piston to move down the cylinder. This movement of piston is transmitted to a crankshaft by a connecting rod so that the crankshaft turns a flywheel . to obtain continuous rotation of the crankshaft this explosion has to be repeated. Before this can happen, the used gases have to be expelled from the cylinder, the fresh charges of fuel and air must be admitted and the piston must be moved back to its starting position.

2. Working Exhaust camshaft:  A rotating shaft that controls the opening and closing of the exhaust valves. Exhaust valve bucket:  A component that sits on top of the valve stem and transfers the motion from the camshaft to open and close the exhaust valve. Spark plug:  A device that ignites the air-fuel mixture in the combustion chamber to initiate the combustion process. Intake valve bucket:  Similar to the exhaust valve bucket, it transfers the motion from the camshaft to open and close the intake valve. Intake camshaft:  A rotating shaft that controls the opening and closing of the intake valves. Exhaust valve:  A valve that opens to allow the exhaust gases to exit the combustion chamber during the exhaust stroke.

3. Intake valve:  A valve that opens to allow the fresh air-fuel mixture to enter the combustion chamber during the intake stroke. Cylinder head:  The topmost part of the engine that houses the combustion chambers, valves, and spark plugs. Piston:  A cylindrical component that moves up and down inside the cylinder, driven by the force generated by the combustion process. Piston pin:  Also known as a wrist pin, it connects the piston to the connecting rod, allowing the piston to pivot.

4. Connecting rod:  Connects the piston to the crankshaft and transfers the linear motion of the piston into rotational motion. Engine block:  The main housing of the engine that contains the cylinders and provides support for various engine components. Crankshaft:  Converts the reciprocating motion of the pistons into rotational motion, which drives the transmission and, ultimately, the wheels.

5. Applications of IC Engines Some of the notable applications of IC Engines are discussed below: Automotive Vehicles : The major application of IC Engine is in cars, motorcycles, trucks, buses, and other vehicles. Aircraft: Another application of IC Engine is to power various types of aircraft, including general aviation planes and some helicopters. Marine Vessels : IC engines are used in boats, ships, and other watercraft for propulsion. Power Generators : IC engines are used in generators to produce electricity for various applications, especially in remote areas and as backup power sources.

6. Construction Equipment : IC engines are found in various construction machinery like excavators, bulldozers, and cranes. Agriculture: Tractors and other farming equipment often use IC engines to perform various tasks on farms. Industrial Machinery : IC engines are used in various industrial machines, including compressors, pumps, and generators. Lawn and Garden Equipment : Lawnmowers, chainsaws, and other gardening tools often use IC engines for power. Small Engine Applications : IC engines power a wide range of small-scale applications like motorised scooters, mopeds, and motorbikes.

7. Advantages of IC Engines Smaller engine size compared to external combustion engines. High power-to-weight ratio. Well-suited for small power requirement applications. Usually more portable than external combustion engines. Safer to operate. Quick starting time. Higher efficiency than external combustion engines. No chances of leakage of working fluids. Requires less maintenance. Lower lubricant consumption compared to external combustion engines.

8. Disadvantages of IC Engines Limited variety of fuels usable, mainly limited to high-quality gaseous and liquid fuels. Expensive fuel options, such as gasoline or diesel, are commonly used. Engine emissions tend to be higher compared to external combustion engines. Not suitable for large-scale power generation. Reciprocating internal combustion engines produce noise due to fuel detonation.

9. Some terminology Indicated Power (IP) Indicated Power (IP) refers to the overall power generated through the combustion of fuel within the combustion chamber. 2. Brake Power (BP) Brake Power refers to the power output available at the engine's output shaft. It represents the power that can be effectively utilised to overcome resistance or counteract the braking forces in the specific application where the engine is employed. 3. Frictional power The Friction Power of an engine is the power needed to overcome internal friction within the engine.

10. 4. Mechanical efficiency The Mechanical Efficiency of an IC Engine is the ratio of the brake power to the indicated power. 5. Volumetric efficiency Volumetric Efficiency of an IC Engine is the ratio of the actual volume of the air or charge drawn into the cylinder during the suction stroke (adjusted to standard conditions) to the swept volume of the piston.  6. Thermal efficiency Thermal Efficiency is the ratio of work done or power developed by an engine to the rate of chemical energy or heat supplied by the combustion of fuel in the engine. It quantifies the efficiency of an engine in converting the heat energy from fuel combustion into useful mechanical work.

11. 7. Compression Ratio The Compression ratio of an IC Engine is the ratio of the total volume of the combustion chamber with the piston at the bottom dead Center (BDC) position to the volume of the chamber when the piston is at the Top Dead Center (TDC) position.  Bottom down center- The furthest extent of the piston's downward (toward the crankshaft) travel is known as the bottom dead center(BDC) position. Top down center- Top dead center, sometimes referred to as TDC, is the point in which the piston in the number one cylinder position of your engine is at its highest point on the compression stroke.