me 2035 fundamental of internal combustion engines and ...api.ning.com/files... · 1 me 2035...

Mechanical Engineering ME 2035

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ME 2035 Fundamental of Internal Combustion Engines and Automobile

A.G.T.I (Second Year)

Part I

Chapter 1 Introduction

1. List the way in which engines can be classified. (10 Marks)

2. Discuss the type of engines as per the operating cycle. (5 Marks)

3. What are the types of the engine according to piston action? (5 Marks)

4. What are the types of the engine according to method of cooling? (5 Marks)

5. How do you classify engines according to speed? (20 Marks)

6. Explain the tow-stroke cycle petrol engine? (20 Marks)

7. With suitable sketch, explain the working of a four-stroke cycle petrol engine.

(20 Marks)

8. Explain the difference between four-stroke and two cycle engine. (15 Marks)

9. Explain the working of a four stroke cycle diesel engine. (20 Marks)

10. Discuss the difference between diesel engine and petrol engine. (15 Marks)

Chapter 3 Fuel Injection Systems

11. Discuss the function required to be performed by a diesel fuel-injection system

(20 Marks)

12. Describe the working principle of a common rail. (20 Marks)

13. List the location where filter is installed in a diesel engine fuel system. (10 Marks)

14. What is the purpose of the water separator? (10 Marks)

15. Describe the working of a fuel-feed pump. (10 Marks)

16. What is the purpose of the fuel injector? (10 Marks)

Chapter 4 Combustion Systems

17. Explain the process of combustion in a diesel engine. (20 Marks)

18. What is the ignition delay? (10 Marks)

19. List the type of the diesel engine combustion chamber. (10 Marks)

20. Describe an open-type combustion chamber with a sketch. (20 Marks)

21. Describe a pre-combustion combustion chamber with a sketch. (20 Marks)


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22. Describe an air-cell type combustion chamber with a sketch. (20 Marks)

23. Describe an energy cell combustion chamber with a sketch. (20 Marks)

Chapter 5 Cooling System

24. Discuss the purpose of engine cooling. (15 Marks)

25. How are the cooling system classified? (10 Marks)

27. How are the water-cooling system classified? (10 Marks)

28. What is the purpose of the water pump? (5 Marks)

29. What is the purpose of the radiator? (10 Marks)

30. Discuss the cooling system used in the marine diesel engine. (20 Marks)

Part 2

Chapter 2 Detail of Engine Parts

30. Describe the action of the piston and the in take and exhaust valve

during each of the jour piston strokes. (20 Marks)

Chapter 4 Electronic Fuel Injection System

31. Explain the electronic fuel injection system. (20 Marks)

32. Describe the sensor that report to the electronic control module. (20 Marks)

34. Explain solenoid – operated fuel injector. (20 Marks)

35. Explain mechanical fuel injector. (20 Marks)

Chapter 5 Carburetor

35. What is the purpose of the carburetor? (10 Marks)

36. Describe the fixed-venturi carburetor system. (20 Marks)

37. Explain the float system. (20 Marks)


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Chapter 1

1. The engine can be classified in many ways. These are

1. operating cycle

2. Piston action

3. Piston connection

4. Number and arrangement of cylinder

5. Valve arrangement

6. Method of fuel system

7. Method of engine cooking

8. Speed

9. Application

2. The type of engines as per the operating cycle are Two-stroke cycle sngine and four

stroke cycle engine.

3. The types of the engine according to piston action are single acting engine and souble

acting engine.

4. The types of the engine according to method of cooling are air-cooled engine and water

engine.

5. Some ways of classification engines according to speed are low speed engine (<1000

rpm), Medium speed engine (between 1000 and 2500 rpm) and High speed engine

(>2500 rpm)

6.


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Compression and power stroke

1. The cycle of events is completed one crank revolve in the two stroke cycle engine.

2. The figure (A) shows a position of the piston on its espward stroke.

3. When the intake transfer and exchaust parts are all covered by the piston.

4. As the piston moves further upwards, the air-fue mixture or its upper side is

compressed.

5. As the same time the ward moving piston uncovers the intake part through.

6. Which the air-fuel mixture from the carburetton is adimitted into the carkcase.

7. At the TDC position of the piston an electric spark egnites the mixture.

8. The burnt gases expand to push the piston downwards.

1. During the downward stroke of the piston, position.

2. Fresh charge of air-fuel mixture, continve to be admitted from the crankcase up to the

position shown in figure (B).

3. At this position the intake part is fully covered by the downward moving position.

4. At the downward movement of the piston,

5. The exhaust part is uncovered by its upper end.

6. This results in the exhaust of the burnt gases.

7. As the same time, the air-fuel mixture Eapped in the crankcase is compressed by the

downward moving piston.

8. At this stage, the upper side of the piston uncovers the transfer part.

9. The transfer of the mixture from the crankcase to the cylinder.


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10. This Eranfer of the mixture and exchaust of burnt gases continues during further

downward stroke of the piston.

11. The piston at B.D.C, bothe transfer and exchaust parts open.

12. During the upward stroke of the piston, the transfer and exhaust parts are covered and

the Eipped air-fuel mixture is compressed.

7.

(1) The induction stroke. Intake stork

1. During this stroke, the piston moves from its top depth centre to bottom depth centre

position,

2. The inlet valve is open and the outlet vlave is closed.

3. As the piston moves downward, there is a partial vacuum in the cylinder.

4. The air-fuel mixture prepared in the carburetton comes into the cylinder through the

inlet part.

5. At the end of the stroke the inlet valve is closed.


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The compression stroke

1. During this stroke the piston moves from B.D.C to TDC and both inlet and exchaust

valves are closed.

2. The piston moving upwards compress the charge of air-fuel mixture due to which its

pressure temperature increases.

Power stroke

1. During this stroke the piston reaches the TDC position at the end of the compression

stroke.

2. The elective spark ignites the air-fuel mixture making the fuel burn.

3. The burnt gases expand causing the piston to move from TDC to BDC.

4. During this stroke both inlet and exhaust valves are closed.


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The exhaust stroke

1. During this stroke the piston moves from BDC to TDC position.

2. The inlet valve closed and outlet valve opens.

3. Due to the upward moving piston force, the burnt gases are taken out of the cylinder

through the open exhaust valve.

8. The difference between four-stroke and two-stroke cycle engine are given below.

Four stroke cycle engine have inlet valve and exhaust valve in the engine head.

Two stroke cycle engine at no valve in this engine.

Four piston cycle engine of events is complete in the two piston strokes. There are

three passages in the cylinder wall, which are controlled by the movement of the piston.

9.


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Suction stroke

1. In this stroke the piston moves from TDC To BDC.

2. The inlet valve opens admitting angle air into the cylinder.

Compression stroke

1. In this stroke, the piston moves from BDC To TDC.

2. Both inlet and exhaust valves are closed.

3. The air is compressed to a high pressure and high temperature

Power stroke

1. At the end of the compression stroke, the fuel is injected in the hot compressed air

through the injector on the cylinder head.

2. The fuel is ignited by the high temperature of compressed air and the resulting

gases push the piston downwards.

3. During the power stroke both inlet and exhaust valves are closed.

Exhaust stroke

1. In this stroke, the piston moves from BDC To TDC.

2. The exhaust valve opens and driving the burnt gases out of the cylinder.

3. At the end of the exhaust stroke, the piston comes to its TDC position.

10. Diesel engine

1. Diesel engine have fuel spray nozzle

2. Diesel engine have not carburetor

3. Diesel engine compression pressure is 350 psi to 500 psi

4. The inlet valve opens admitting only air into the cylinder.

Petrol engine

1. Petrol engine have carburattor and spark dug on cylinder head

2. Petrol engine compression pressure is so psi to 150 psi.

3. At the end of the compression stroke the electric spark ignites the air fuel mixture making

the fuel burn.

4. The air fuel mixture prepared in the carburetor comes into the cylinder through the inlet

port.


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Chapter (3)

11. Fuel injection system

1. Discuss the function required to be performed by a diesel fuel-injection system.

The fuel injection system of a diesel engine is required to perform the following

functions.

1. To develop the high pressure required to inject fuel in the cylinder. This pressure is of

the order of 200 to 300 kg F/cm2.

2. To meter or measure the correct quantity of Fuel for injection. The quantity varies

according to engine load and speed.

3. To inject the fuel at the correct time.

4. The rate of fuel injection should not be too slow or too fast. Thus too or too fast

injection rate have the same effect as incorrect timing.

5. To atomize (break up) the fuel into fine particles.

6. To distribute the fuel in the combustion chamber such that it will reach all parts of the

combustion chamber, where air is available.

This will result in better mixing of air and fuel and better combustion of Fuel.

12.

1. Common rail system, the pressure required to injection the fuel is developed in a pump.

2. The timing and metering of the fuel is accomplished in the injector.

3. Figure shows the schematic functioning of a common rail system.


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4. The fuel, at a high pressure, is supplied to a common rail system by the high pressure

fuel pump.

5. A spring loaded by pass valve maintains constant pressure on the common rail and

returns the excess fuel.

6. The pressure of the common rail can be adjusted by adjustment of the spring tension on

the bypass valve.

7. From the common rail, the fuel is distributed to the individual injectors by different fuel

lines.

8. Each injector contain a needle valve seated against the valve seat by a spring.

9. The valve is operated by a cam-follower-push rod-rocker arm mechanism.

10. The push rod is in two parts with a control wedge between its to portions.

11. The wedges of the different push rods are all connected to the governor or hand control.

12. When the thicker portion of the control wedge is between the two portions of the push

rod,

13. The effective length of the push rod increases, causing increase in the valve lift and in

the quantity of the fuel injected.

13. Filter is installed in a diesel engine fuel system

1. The diesel engine fuel injection pump and fuels injectors are manufactured to very close

to clearance.

2. If the diesel sent to these components is clean and chemically satisfactory.

3. There will be very little wear of these components even after prolonged operation.

4. So fuel filter is installed in the fuel injection system.

14. The purpose of the water separator.

1. The water in diesel may cause trouble in the operation of the engine as also rusting and

rapid wear of components

2. In the diesel supply system to prevent the water from going to the system.

15.

1. Fuel feed pump is used for transfer of fuel from the tank to the injection pump.

2. This pump is usually an integral part of the fuel injection pump and is driven by the cam

shaft of the fuel injection pump.


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3. A hand primer is provided on the suction side of the fuel feed pump for bleeding of the fuel

system.

16.

1. The power developed by the engine should always by equal to the load on the engine.

2. Hence the supply of fuel should be changed when there is change of engine load.

17.

1. The fuel injector purpose of fuel injection system, receive fuel under pressure from the

fuel injection pump at the proper time.

2. Supplies this fuel to the combustion chamber in the form of a fine spray.

Chapter -4

18. Combustion systems

The process of combustion in a diesel engine, the following requirements should be

met,

(1) Fine atomization

This is achieved by supplying the fuel at a very high pressure through small orifice of

the injector.

(2) Proper Distribution of fuel

This depends on the injection pressure and location of the injector.

(3) High Temperature for prompt Ignition

The temperature of compressed air is dependent on the compression ration, engine

size and cooling arrangement.

(4) Air motion

A high relative velocity between fuel and air particles is desired so as to achieve

better combustion. This is dependent on the design of the combustion chamber.

(5) Proper Mixing of Air and Fuel

This also depends upon the design of the combustion chamber and the spray pattern.

19.

1. The ignition delay is the rate of fuel injection should not be too fast or too slow.

2. Too fast injection will cause greater ignition delay.


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20. Diesel engine combustion chambers are

1. Open combustion chamber

2. Turbulence combustion chamber

3. Pre combustion chamber

4. Air-cell

5. Energy cell.

21.

1. Open type combustion chamber, all air at the time of the fuel injection is in a single

space and the fuel is injected directly in to the space.

2. The simples design of the open combustion chamber consists of a flat cylinder head and

a flat piston crown.

3. In modern designs the combustion space is made in the piston crown.

4. The different shapes of the open type combustion chamber are shown in figure

5. The piston top and cylinder head are very close to each other at TDC and a very small

clearance is provided between the two for mechanical reasons.

6. Open combustion chamber are generally used on medium and large size engines which

operate on moderate speeds.

7. This type of combustion, it is desirable to have higher injection pressures.


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22.

1. The pre-combustion chamber is also located outside the main cylinder.

2. How ever the contains only about one third the air change at end of the compression

stroke.

3. The remaining air is held in the main chamber.

4. Figure shows one design.

5. The pre-combustion chamber is approximately cylindrical in shape and the fuel nozzle

is located at one end.

6. The fuel spray is directed towards the throat.

7. When the fuel is injected in the pre-combustion chamber, the excessively rich fuel-air

mixture will burn with an insufficient amount of air resulting in its expansion.

23.


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1. Air cell combustion chamber design is an auxiliary chamber which may be located

within the piston or outside the main cylinder.

2. Where a portion of compressed air is trapped at the end of the compression stroke.

3. However, unlike the turbulence or pre-combustion type chamber.

4. The fuel in this design is injected into the main combustion space.

5. The air in the air cell close to the maximum pressure.

6. When the piston starts its motion from TDC towards BDC there is a reduction of

pressure in the main chamber.

7. The higher pressure in the air cell causes its air to move towards the main combustion

space.

8. This causes additional turbulence and better burning of fuel is obtained.

9. Fig-shows an air-cell combustion chamber located in the piston.

24.

1. Shown in figure the design of a energy cell combustion chamber.

2. A narrow passage joints the main combustion space to the energy cell made in two

parts.

3. This energy cell will hold about 10% of the air volume at the end of the compression

stroke.


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4. The fuel nozzle is at the other end of the main combustion space such that the spray is

directed towards the passage connecting the main combustion space to the energy cell.

5. Near the end of the compression stroke, the fuel is sprayed in the combustion space in

the direction of the mouth of the energy cell.

6. A part of this fuel, while traveling through the centre of the main chamber burns.

7. The remaining fuel enters the energy cell and starts to burn there

8. The pressure in the energy cell rises due to this, and the products of combustion flow

back to the main combustion space at a high velocity.

9. This causes a swirling action of air and fuel in the two sections of the main combustion

space.

10. This results in better combustion.

Chapter 5

25. Cooling systems

1. The combustion of a fuel in diesel engine produces temperature.

2. Some of the heat produce by combustion is absorbed by the cylinder head, valves,

cylinder walls and piston.

3. This heat has to be removed so that these parts do not get much hot.

4. The temperature of the cylinder walls should not be allowed to increase, 200-250 C.

5. However, too much cooling of the engine is also not desirable.

6. The cooling of engine means carrying away of the heat energy of the fuel which could

otherwise be converted into the work.

7. Thus too much cooling will results in lower thermal efficiency of the engine.

26. The cooling system classified are two types.

1. These are air cooling system, include of two and three wheels, airplanes and small

stationary engines.

2. Next, cooling system is water cooling system, include of water jackets, water pump,

fan, radiator, thermostat, Radiator pressure cap and temperature indicators.


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27.

1. The purpose of the water pump installed in cooling system.

2. Water pump driven by a v-belt from a pulls on the engine crank shaft is used to

circulate the water.

28.

1. The purpose of the radiator is installed in cooling system.

2. The radiator is a heat exchange device which transfers the heat of water to the air.

3. If consists of an upper tank, a core and a lower tank.

4. The upper tank is connected to the water outlet from the jackets through top hose and

the lower tank is connected to the pump inlet through the bottom hose.

5. Two designs of radiator core are commonly use tubular and cellular.

29.

1. The schematic diagram of a typical water-cooling system used in a marine engine is

shown in figure.

2. This is a closed-type cooling system with a water-to-water heat exchanger, the

secondary water being obtained from the sea or river

3. After passing through the engine, the primary water (soft water) passes to the heat

exchanger where its heat is absorbed by secondary water (raw water).

4. A by pass control is placed around the heat exchanger to control the water temperature.

5. After being cooled in the heat exchanger, the primary water flows back to the engine

water jackets.


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6. An expansion tank is used in the system, to which a pipe from the pump, suction side is

connected

7. This arrangement allows the closed cooling system to overcome the variation in water

volume resulting from expansion and contraction due to heating and cooling.

8. The secondary (raw) water pump draw water from the sea or river.

9. This secondary water is then passed through the lubrication oil cooler and heat

exchanger, after which it is discharge back to the sea or river

10. The system describe is also used in industrial installations, where ample raw water

supply is available.

30. Piston Engine Operation

1. Engine Construction

(a) Spark ignition engine and compression ignition engine are similar in construction.

(b) They both have pistons that move up and down in cylinder.

(c) The same actions take place in each cylinder usually at equally spaced intervals of the

crank shaft rotation as long as engine run.

(d) Automotive engine have three or more cylinder.

Engine Operation

1. The action or events in the spark ignition engine can be divided into four parts.

2. These are intake, compression, power and exhaust.

3. Each stroke is the movement of the piston from BDC to TDC or from TDC to BDC.


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Intake stroke

1. During the intake stroke of a spark ignition engine the intake valve is open and the piston

is moving down.

2. This creates a partial vacuum above the piston.

3. Atmospheric pressure air-fuel mixture to flow through the intake port and into the cylinder.

4. As the piston passes through BDC, the intake valve close.

5. This seats off the upper end of the cylinder.

Compression stroke

1. After the piston passes BDC, it starts moving up.

2. Both valves are closed.

3. The upward moving piston compresses the air-fuel mixture into a smaller space between

the top of the piston and the cylinder head.

4. This is the combustion chamber

5. In a typical spark ignition engine, the mixture is compressed into one-eight or less of its

original volume.

Power stroke

1. As the piston near TDC at the end of the compression strake, an electric spark jumps the

gap at the spark plug.

2. The heat from the spark ignites the compressed air-fuel mixture.

3. It burns rapidly, producing high temperature of up to 4500 F (2182 C).

4. These high temperature causes very high pressure which pushes down on the top of the

piston.

5. The connecting rod carries this Fo to the crank shaft.

6. Which turns to move the drive wheels.

Exhaust stroke

1. As the piston approaches BDC on the power stroke the exhaust valve opens.

2. After passing through BDC, the piston moves up again.

3. The burned gases escape through the open exchange port.

4. As the piston nears TDC, the intake valve opens.

5. So as the end of the exhaust stroke.


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31. Electronic Fuel injection system

Engines in most 1980 and later automotive vehicle have an electronic engine control

(EEC) system.

It uses a computer to control the ignition, fuel metering and, other related systems.

On most automotive engine fuel metering is performed by an electronic fuel injection

(EFI) system.

Two type of the spark ignition engines are

Multiport fuel injection (MFI) which has a fuel injection in each intake port.

Throttle-body fuel injection (TBI) in which one or two fuel injection are located

above the throttle valves.

with either system;

1. The electric fuel pump supplies the injectors with the fuel under pressure

2. When the engine computer signals the injector a solenoid-operated valve opens as the

end of the injection.

3. The pressure Fo the fuel to spray out.

4. When the proper amount of fuel is injected into the passing air, the valve closes and fuel

injected stops.


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Simplified electronic fuel injection

1. Figure shows the components in a simplified electronic fuel injection system.

2. Most of fuel injection systems are electronically controlled.

3. The controller is the engine computer an electronic control module (ECM) or power

train control module (PCM )

4. It is also called the onboard computer because it is on board the vehicle.

5. Various parts of the engine and fuel system have sensors that send electric signals to the

ECM.

6. Each sensor is a device that receives and reacts to a signal such as a change in

temperature, pressure or voltage.

7. Some sensors reports the amount of air entery.

8. Using this information, the ECM continuously calculates how much fuel to inject.

9. It then opens the fuel injectors so the proper amount of fuel sprays out to produce the

desired air-fuel rotio.

32. An electronic fuel injection system is a type of electronic control system.

It includes sensors or input devices a controller (ECM or PCM) and various actuators or

output devices that are operated by the ECM or PCM.

Sensors that report to the ECM include

(1) Engine speed

(2) Throttle position

(3) Intake manifold vacuum or manifold absolute pressure

(4) Engine coolant temperature

(5) Amount and temperature of the intake air solenoid-operated fuel injector


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33. Solenoid

(1) The solenoid-operated injector is turned on and off by the ECM.

(2) A electric solenoid in the injector opens and closes it.

(3) The solenoid has a small coil of wire that becomes magnetized when a voltage is applied.

(4) The magnetism lifts the armature which rises a needle valve or pintle off its seat.

(5) Fuel sprays out as long as the pintle is raised.

(6) When the voltage stops, the coil loses its magnetism.

(7) Then the closing spring pushes the pintle back down onto the seat.

(8) This stops the fuel spray.

34. Mechanical Fuel Injector

1. The figure shows a continuous injection system.

2. It has a mechanical fuel injector a each intake port.

3. The injector is basically a fixed orifice with a pressure operated needle valve in the end.

4. The amount of the fuel injected depends on the pressure applied to the fuel.


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5. The open and closed positions of the needle valve in the mechanical injector are shown

in figure.

6. As fuel flows through, the passing fuel causes the needle valve to open and close

rapidly.

7. This chattering, which sometimes can be heard helps break the fuel into a fine mist

while the engine is running.

8. When the ignition key is turned off, the electric fuel pump stops and fuel pressure

drops.

9. Then the spring forces the needle valve to remain closed.

10. This prevents fuel from dribbling into the intake part.

Chapter 5

35. Carburetors

Purpose

The carburetor is a mixing device that can supply a spark ignition engine with a

combustible mixture of air and fuel.

The carburetor is mixing device that can supply a spark ignition engine with a

combustible mixture of the air and fuel. Two basic type of carburetor are based on

automobile engines. These are the fixed-venturi (FV) carburetor and the variable-venturi

(VV) carburetor.

36. Fixed-venturi carburetor systems

(1) Float system

(2) Idle system

(3) Main metering system

(4) Power system

(5) Accelerator-pump system

(6) Choke system


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37. Float system

In the carburetor, the float bowl is supplied with fuel from the fuel tank by a fuel

pump.

(2) The figure shows the float system

(3) A vent in the top of the float bowl allows the atmosphere pressure to act on the fuel in

the float bowl.

(4) The atmospheric pressure pushes the fuel up through the fuel nozzle

(5) If air is passing through the carburetor, the air flow through the venture produces a

vacuum around the discharge end of the fuel nozzle.

(6) The resulting pressure differential causes fuel discharge from the fuel nozzle.

(7) The resulting pressure differential causes fuel discharge from the fuel nozzle into the

passing air.

(8) The float system includes a small fuel reservoir with a float and needle valve.

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