03 2 internal combustion engine arm

INTERNAL COMBUSTION ENGINE

AE 422Agricultural Power and

Its Sources

STUDENTAttendance Quiz

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Acay, Noreen Grace 30

Barbo, Herloid Cesar 30

Bayan, Charlie 1

Borda, Renaldo 14

Borero, Saidamen 31

Duran, Iza Roseline 16

Eslao, John Fernan 30

Flores, Precious 18

Gallera, Jose Bernie 9

Scores and Attendance


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Gomez, Franklin 13

Lampon, Melvin 23

Mateo, Abigail 12

Omega, Julius 26

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Pino, Fatima 27

Reponte, Maricel 15

Salik, Naila 26

Samillano, Denard 20

Travilla, Charles 20



Total Absent


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Pavo, June Carlo 3

Florido, Florievic 23

Sasi, Precious Anne 31

Nadala, Sonie 27

Garcia, Jacklyn A 25


Short Quiz (50 pts)

1) Define Engine (10)

2) What are the two types of Heat Engine (4)

3) Enumerate the Conditions for ICE to achieve maximum efficiency as stated in Beau de Rochas Principle (10)

Figure 3.2.1

4.) Identify the following engine based on position and number of cylinder (12 pts)

Figure 3.1.2

a

b

c

de

f

f

g

h

i

j

k

l

5) Identify the Parts of an Enginer (14 pts).

Pass your Papers

Answers

Define Engine.

An engine is a mechanical device used to convert the heat energy of fuel produced by combustion into mechanical energyTwo types of engine

● External Combustion Engine● Internal Combustion Engine

Answers

Define Engine.

An engine is a mechanical device used to convert the heat energy of fuel produced by combustion into mechanical energyTwo types of engine

● External Combustion Engine● Internal Combustion Engine

Answers

Conditions for ICE to achieve maximum efficiency:

1. The largest possible cylinder volume with the

minimum boundary surface

2. The largest possible working speed

3. The greatest possible expansion ratio

4. The greatest possible pressure at the beginning of

expansion

AnswersPosition and Number of cylinders of reciprocating engines

Single cylinderIn-lineV-engineOpposed cylinder engineOpposed piston engineW-engineRadial engine

Answers

LAWS OF THERMODYNAMICS1ST LAW OF THERMODYNAMICS• Law of the conversion of energy• States that “When heat energy is transformed into

mechanical energy, the work done is equivalent to the quantity of heat involved.”

2nd LAW OF THERMODYNAMICS• States that “Heat will, of itself pass from a hot to a

cold substance, but external work is required to transfer heat from a cold substance to a hot substance.”

2 ways in which combustion takes place in ICE

1. By rapid explosion of mixture within cylinder when it is ignited by a spark (constant-volume process)

2. By relatively slow burning as the fuel is injected into highly compressed, heated air (constant –pressure process)

ICE PRINCIPLESASSUMPTIONS:• Air pressure during intake stroke (AB) is atmospheric• Compression and expansion are adiabatic process• Specific heat remains constant through out the cycle

CYCLE OF OPERATIONS

ENGINECYCLE

1 2

34

1. Intake Stroke•. Begins with the piston moving down•. Intake valve opens and a fuel mixture

(in SI) or air alone (in CI) enters the cylinder

•. At the completion of this stroke, the piston is at the bottom of the cylinder and both valves are closed.

4-STROKE CYCLE PRINCIPLES

2. Compression Stroke➢ When the piston reaches at the bottom

of the cylinder on the intake stroke it starts upward

➢ Both valves are closed➢ At the top of this stroke, the fuel

mixture is compressed tightly


3. Power Stroke•. A spark from the spark plug ignites the mixture•. Results to rapid expansion of the burning mixture•. Piston is pushed downward•. Still, both valves are tightly closed

4. Exhaust Stroke•. When the piston reaches the bottom, it starts moving

upward•. As the piston moves up, the exhaust valve opens and

the exhaust fumes are pushed out of the cylinder•. Exhaust stroke is completed with the piston at TDC•. Cycle is repeated


Intake & Exhaust Strokes ü Uncovers the intake and exhaust ports as the

piston nears the bottom of its strokeü Because air-fuel mixture (SI) or air (CI) in the

crankcase is under pressure, it rushes through a passage to the intake port and enters the cylinder

ü This incoming fuel mixture (SI) or air (CI) pushes the exhaust gases out of the cylinder

ü Therefore, intake and exhaust functions occur with very little movement of the piston


• Compression Strokeü the cylinder now is filled with the fuel

mixture (SI) or air (CI)ü Pistons moves upward, closes the

intake and exhaust ports and compresses the fuel mixture

ü At the same time, new supply of air and fuel rushes in the crankcase


• Power Strokeü At or near TDC, the spark plug fires the mixture

(SI) or fuel is injection into the cylinder (CI)ü The burning and expanding gases drive the piston

downwardü This same downward movement puts pressure on

the new air-fuel mixture in the crankcase pushing it into the cylinder (which in turn pushes the exhaust gases out of the cylinder )

ü Thus, the engine completes its cycle of intake, compression, power and exhaust with only two strokes of the piston.


Operation of 2-stroke spark ignition engine


Lighter weight (no mechanical valves, eliminating the camshaft to operate the valves)

Lubricating oil is mixed with the fuel and there is no sump to hold engine oil allowing engine to operate in any position even upside down.

ADVANTAGE OF 2-STROKE OVER 4-STROKE

THEORY OF OPERATION• The function of all internal combustion engines is to

convert fuel (chemical energy) to power.• Accomplished by burning a fuel in a closed chamber

and using the increase in temperature within the closed chamber to cause a rise in pressure

• Pressure produces a force on the head of the piston causing it to move

• The linear movement of the piston is converted to rotary motion (at the crankshaft)

• Rotary motion is more useful than linear movement

EIGHT (8) REQUIREMENTS FOR OPERATION

1) Air (oxygen) is drawn into the engine cylinder.

2) A quantity of fuel is introduced into the engine.

3) The air and the fuel are mixed.4) The fuel–air mixture is compressed.

EIGHT (8) REQUIREMENTS FOR OPERATION

5) The fuel–air mixture is ignited by the spark plug in gasoline engines or by the heat of compression in diesel engines.

6) The burning of the fuel–air mixture causes a rapid pressure increase in the cylinder, which acts against the piston, producing a force on the piston.

7) The use of a connecting rod and a crankshaft converts the linear movement of the piston to rotary motion.

8) The force on the piston is converted to torque on the crankshaft.

Reminders:

● Next Module: Engine Operating Characteristics– References

● Goering, Carroll E., and Alan C. Hansen. 2004. Practical Engine Cycles and Timing. Chapter 2- 3 in Engine and Tractor Power, 4th edition, St. Joseph, Michigan: ASAE. © American Society of Agricultural Engineers.

● Roth, Alfred C. Small Engines

Education

03 2 internal combustion engine arm