Internal Combustion Engines - MechFamilymechfamilyhu.net/downloads/INTERNAL COMBUSTION/CHAPTERS/cha… · Internal Combustion Engines Introduction : 1 2 ... – Opposed piston . Internal

Internal Combustion Engines Introduction : 1

1

Internal Combustion Engines

IntroductionLecture 1

Internal Combustion Engines Introduction : 1

2

Outline

• In this lecture we will learn about:– Definition of internal combustion– Development of the internal combustion

engine– Different engine classifications

• We will also draw a comparison between the S.I. Engines and the C.I. Engines.

Internal Combustion Engines Introduction : 1

3

Introduction• The Internal Combustion (I.C.) engine is a heat

engine that converts chemical energy (in the fuel) into mechanical energy (available on a rotating shaft).

• Internal Vs. External combustion.• History:

– 1859 Discovery of oil.– 1876 First four stroke spark ignition engine

produced by Nicholas Otto.– 1888 Pneumatic rubber tire invented by John

Dunlop– 1892 First compression ignition engine produced

by Rudolph Diesel.

Internal Combustion Engines Introduction : 1

4

Engine ClassificationsInternal combustion engines can be classified in a number of ways:

• Basic Design:– Reciprocating: Piston-

Cylinder arrangement– Rotary: Rotor-Stator

arrangement

Internal Combustion Engines Introduction : 1

5

Engine Classifications

• Type of ignition:– Spark Ignition (S.I.)– Compression Ignition (C.I.)

• Engine Cycle:– Four-Stroke Cycle: four piston movements

over two engine revolutions / cycle– Two-Stroke Cycle: two piston movements

over one revolution / cycle

Internal Combustion Engines Introduction : 1

6

Engine Classifications

Internal Combustion Engines Introduction : 1

7

Engine Classifications

Internal Combustion Engines Introduction : 1

8

Engine Classifications

• Valve Location:– In the head

(overhead valve / I head )

– In the block (Flat head / L head )

– One in the head, one in the block (F head)

Internal Combustion Engines Introduction : 1

9

Engine Classifications

• Position and number of cylinders:– In-line (straight):

most common 4 cylinders

– V Engine: V6 and V8 most common

Internal Combustion Engines Introduction : 1

10

Engine Classifications

– Opposed cylinder (flat): small aircrafts

– Opposed piston

Internal Combustion Engines Introduction : 1

11

Engine Classifications

– Radial Engine: large aircraft and ship engines

– W Engine: rare –racing purposes

– Single cylinder: research purposes

Internal Combustion Engines Introduction : 1

12

Engine Classifications

• Method of fuel input (S.I. engines):– Carburetted– Fuel Injection:

• Multipoint port fuel injection (at the cylinder intake)

• Throttle body fuel injection (in the manifold)

Internal Combustion Engines Introduction : 1

13

Engine Classifications• Air intake system:

– Naturally aspirated– Charged (Intake air

pressure increased):• Supercharged: using

compressor driven by crankshaft

• Turbocharged: turbine-compressor driven by exhaust gases flow

Internal Combustion Engines Introduction : 1

14

Engine Classifications

• Type of cooling:– Air cooled– Liquid cooled

• Fuel used:– Gasoline (Petrol / Benzene)– Diesel– Other (Gas, LPG, Alcohol….etc)

Internal Combustion Engines Introduction : 1

15

Engine Classifications

• Application:– Automotive– Locomotive– Aircraft– Marine– Stationary– Small portable

Internal Combustion Engines Introduction : 1

16

Engine Classifications

Internal Combustion Engines Introduction : 1

17

(S.I. Engines) Vs. (C.I. Engines)• Fuel Economy:

– C.I. engines are more economic due to the higher thermal efficiency (30-40% compared to 20-30 %) because of the higher compression ratios.

• Power and torque:– S.I. engines are more powerful at higher speeds due

to their shorter stroke and wider speed range.• Reliability:

– C.I. engines are more robust, run cooler and generally have a longer life.

Internal Combustion Engines Introduction : 1

18

(S.I. Engines) Vs. (C.I. Engines)• Safety:

– Fire risk is less in C.I. engines since diesel (unlike petrol) is not flammable at normal operating temperatures.

• Cost: – C.I. are more expensive due to their heavy

construction and advanced injection equipment.• Pollution:

– C.I. engines produce less CO and CO2 but more NOxand much more particulates (soot).

Internal Combustion Engines Introduction : 1

19

Activity #1

• In teams of 2 students each:– Pick a modern passenger car model and

examine its engine. – Then classify this engine according to the

engine classifications discussed in this lecture.

– Submit your report within one week from today.