Contents INTRODUCTION OF I.C. ENGINE EC AND IC ENGINES INTERNAL COMBUSTION ENGINES CLASSIFICATION OF I.C. ENGINES COMPONENTS OF I.C. ENGINES TWO STROKE ENGINE FOUR STROKE PETROL ENGINE CARBURETTOR DIESEL ENGINE DIESEL PUMP MPFI and CRDI ENGINE PERFORMANCE PERFORMANCE CALCULATION 4 STROKE Vs 2 STROKE ENGINE PETROL Vs DIESEL ENGINE

Introduction of I.C. Engine Heat Engines – A machine or device which derives heat from the combustion of fuel and converts it into mechanical work is called a heat engine

EC and IC Engines types of heat engines steam engines external combustion turbines Stirling engine Otto engine internal combustion Diesel engine Wankel engine

Internal Combustion Engines In this case, combustion of fuel with oxygen of the air occurs within the cylinder of the engine. Application of I.C. Engines (i) Road vehicles, locomotives, ships and aircraft, (ii) Portable standby units for power generation in case of scarcity of electric power, (iii) Extensively used in farm tractors, lawn movers, concrete mixing devices and motor boats.

Internal Combustion Engines The internal combustion engine is an engine in which the combustion of fuel-oxidizer mixture occurs in a confined space applied in: automotive rail transportation power generation ships aviation garden appliances

Internal Combustion Engines

Classification of I.C. Engines The internal combustion engines may be classified in the following ways: 1. According to the type of fuel used a) Petrol engines, b) Diesel engines, and c) Gas engines. 2. According to the method of igniting the fuel a) Spark ignition engines, and b) Compression ignition engines. 3. According to the number of strokes per cycle a) Four stroke cycle engines, and b) Two stroke cycle 4. According to the cycle of operation a) Otto cycle engines, b) Diesel cycle engines, and c) Dual cycle engines.

Classification of I.C. Engines 5. According to the speed of the engine a) Slow speed engines, b) Medium speed engines, and c) High speed engines. 6. According to the cooling system a) Air-cooled engines, and b) Water-cooled engines. 7. According to the method of fuel injection a) Carburetor engines, and b) Air injection engines. 8. According to the number of cylinders a) Single cylinder engines, and b) Multi-cylinder engines.

Classification of I.C. Engines 9. According to the arrangement of cylinders a) Vertical engines, b) Horizontal engines, c) Radial engines, d) In-line multi-cylinder engines, e) V-type multi-cylinder engines, f) Opposite-cylinder engines, and g) Opposite-piston engines. 10. According to the valve mechanism a) Overhead valve engines, and b) Side valve engines. 11. According to the method of governing a) Hit and miss governed engines, b) Quantitatively governed engines, and Qualitatively governed engines.

Internal Combustion Engines – multi-cylinder - inline Cylinder layouts flat V TYPE

Internal Combustion Engines – multi-cylinder - inline flat „boxer” V

Internal Combustion Engines – multi-cylinder - 14 cylinder Diesel engine (80 MW)

Internal Combustion Engines – multi-cylinder - Cylinder layouts radial

Components of I.C. Engines A. Parts common to both Petrol and Diesel engine: 1. Cylinder, 2. Cylinder head, 3. Piston, 4. Piston rings, 5. Gudgeon pin, 6. Connecting rod, 7. Crankshaft, 8. Crank, 9. Engine bearing, 10. Crank case. 11. Flywheel, 12. Governor, 13. Valves and valve operating mechanism. B. Parts for Petrol engines only: 1. Spark plug, 2. Carburetor, 3. Fuel pump. C. Parts for Diesel engine only : 1. Fuel pump, 2. Injector.

1. Cylinder/Engine block It is one of the most important part of the engine, in which the piston moves to and fro in order to develop power. The engine cylinder has to withstand a high pressure (more than 50 bar) and temperature (more than 2000 deg C). Thus the material for the engine cylinder should be such that it can retain sufficient strength at such a high pressure and temperature. For ordinary engines, the cylinder is made of ordinary cast iron. But for heavy duty engines, it is made of steel alloys or aluminum alloys.

2. Cylinder head It is fitted on one end of the cylinder, and act as a cover to close the cylinder bore. Generally, the cylinder head contains inlet and exit valves for admitting fresh charge and exhausting the burnt gases. In petrol engines, the cylinder head also contains a spark plug for igniting the fuel-air mixture, towards the end of compression stroke. But in diesel engines, the cylinder head contain nozzles, (i.e. fuel valve) for injecting the fuel into the cylinder

3. Piston – Its main function is to transmit the force to the connecting rod and is made of aluminum alloys which are light in weight. 4. Piston rings – These are circular rings and made of special steel alloys which retain elastic properties even at high temperatures. The piston rings are housed in the circumferential grooves provided on the outer surface of the piston. The function of the upper rings is to provide air tight seal to prevent leakage of the burnt gases into the lower portion. Similarly, the function of the lower rings is to provide effective seal to prevent leakage of the oil into the engine cylinder.

5. Connecting rod – It is a link between the piston and crankshaft, whose main function is to transmit force from the piston to the crankshaft. Moreover, it converts reciprocating motion of the piston into circular motion of the crankshaft, in the working stroke. 6. Crankshaft – It is considered as the backbone of an I.C. engine whose function is to covert the reciprocating motion of the piston into the rotary motion with the help of connecting rod. 7. Crank case – It is a cast iron case, which holds the cylinder and crankshaft of an I.C. engine. It also serves as a sump for the lubricating oil.

8. Flywheel – It is a big wheel, mounted on the crankshaft, whose function is to maintain its speed constant. It is done by storing excess energy during power stroke, which, is returned during other stroke.

COMPONENTS

Parts Of An Engine. PISTON VALVE SPARK PLUG CAM SHAFT

Internal Combustion Engines – two stroke - 2. Intake / Compression 1. Power / Exhaust ignition piston moves downward compressing fuel-air mixture in the crankcase exhaust port opens inlet port opens compressed fuel-air mixture rushes into the cylinder piston upward movement provides further compression

Cycle of operation in two stroke engine

Internal Combustion Engines – two stroke - Advantages: lack of valves, which simplifies construction and lowers weight fire once every revolution, which gives a significant power boost can work in any orientation good power to weight ratio Drawbacks: lack of a dedicated lubrication system makes the engine to wear faster. necessity of oil addition into the fuel low efficiency produce a lot of pollution

Internal Combustion Engines – four stroke - a. piston starts moving down b. intake valve opens c. air-fuel mixture gets in 1. intake a. piston moves up b. both valves closed c. air-fuel mixture gets compressed 2. compression starting position

Internal Combustion Engines – four stroke - ignition a. air-fuel mixture explodes driving the piston down 3. power a. piston moves up b. exhaust valve opens c. exhaust leaves the cylinder 4. exhaust

Cycle of operation in four stroke engine

Internal Combustion Engines – four stroke - Advantages: dedicated lubrication system makes to engine more wear resistant better efficiency that 2-stroke engine no oil in the fuel – less pollution Drawbacks: complicated constriction should work in horizontal position due to lubrication

Internal Combustion Engines – four stroke - air intake exhaust /intake compression fuel injection combustion exhaust

Theoretical P-V diagram of Four stroke Engine

Actual P-V diagram of a four stroke Otto cycle Engine

Theoretical valve timing diagram for four stroke Otto cycle engine

Actual Valve timing diagram for four stroke Otto cycle diagram

PV diagram for a two stroke cycle engine

Port Timing Diagram – 2 stroke

PETROL ENGINE CARBURATOR SPARK PLUG LESS POLUTION MORE POWER

Carburettor The process of preparing air-fuel mixture away from the engine cylinder is called carburetion. and the device in which this process takes is called carburetor.

Carburettor

Functions of carburetor 1. To mix the air and fuel thoroughly 2. To atomize the fuel 3. To regulate the air- fuel ratio at different speeds and loads on the engine. 4. To supply correct amount of mixture at different speeds and loads

DIESEL ENGINE INJECTOR PUMP More POLUTION High COMPRESSOIN RATIO (15:1 to24:1) MILLAGE

DIESEL PUMP Main functions Supply of diesel in the form of vapour at the time of combustion Supply of required quantity of diesel to meet the variable load condition of the engine

DIESEL PUMP

MPFI Multi Point Fuel Injection system Each cylinder has number of  injectors to supply/spray fuel in the cylinders as compared to one injector located centrally to supply/spray fuel in case of single point injection system.

MPFI

MPFI Advantages (1) More uniform A/F mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. Vibration from the engine equipped with this system is less, due to this the life of engine components is improved. 2) No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system. (3) Immediate response, in case of sudden acceleration / deceleration. (4) Since the engine is controlled by ECM* (Engine Control Module), more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level. (5) The mileage of the vehicle will be improved. 

MPFI:- multi point fuel injection system MPFI:- multi point fuel injection system. it is used in gasoline(petrol) engines. it simply replaces the carburetors used in petrol engines. with high efficiency than carburetors instead injecting the fuel in common central point of intake, injectors inject the fuel in intake ports of each cylinder’s intake valve. which helps in maintaining good combustion in each cylinder and generates high efficiency.

CRDI

CRDI:- Common rail direct injection system CRDI:- Common rail direct injection system. used in diesel cars (hyundai uses this tech.) it means the fuel is injected in the cylinder through a common rail maintained at very high pressure (upto 600 bar) wrt the cylinder pressure which helps in fast injection of fuel with less delay time and good combustion. which results in better efficiency.

ENGINE PERFORMANCE Engine performance is an indication of the degree of success of the engine performs its assigned task, i.e. the conversion of the chemical energy contained in the fuel into the useful mechanical work. The performance of an engine is evaluated on the basis of the following : (a) Specific Fuel Consumption. (b) Brake Mean Effective Pressure. (c) Specific Power Output. (d) Specific Weight. (e) Exhaust Smoke and Other Emissions

Performance calculation 1. brake power (bp) where, T is torque in N-m N is the rotational speed in revolutions per minute. 2. Indicated Power where, pm = Mean effective pressure, N/m2, L = Length of the stroke, m, A = Area of the piston, m2, N = Rotational speed of the engine, rpm (It is N/2 for four stroke engine) k = Number of cylinders.

Performance calculation The basic performance parameters calculated (a) Power and Mechanical Efficiency. (b) Mean Effective Pressure and Torque. (c) Specific Output. (d) Volumetric Efficiency. (e) Fuel-air Ratio. (f) Specific Fuel Consumption. (g) Thermal Efficiency and Heat Balance. (h) Exhaust Smoke and Other Emissions. (i) Specific Weight.

Performance calculation

Performance calculation

Performance calculation Mean effective pressure

Performance calculation

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