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Basic Mechanical Engg(S1S2 EEE-2011)

Module 1, Part-3

MATHEW JOHN

Assistant ProfessorDept of Mechanical Engg

Govt. Engineering College Barton Hill

Thiruvananthapuram-35

IC Engines - Various Systems

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Introduction

I IC Engines ( SI & CI , 2S & 4S)

II General description of Various systems

(a) Air System

(b) Fuel System

(c) Ignition System (SI engine)

(d) Governing System

III Recent Developments(a) CRDI - CI engines

(b) MPFI & GDI SI engines

(c) Hybrid Vehicles

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3

Four Stroke Engine (SI)

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4

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5

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Cam Shaft

Crank Shaft

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Firing Order 1-2-4-3

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Engine Performance Curves

Part Load efficiency less-hence electric

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Air system-Petrol Engine

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Atmospheric Air Air Filter Carburettor Intake Manifold(air cleaners)

Exhaust to atm Silencer Catalytic Convertor Engine Cylinder

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Air Cleaners(for SI)

Heavy duty type

Light duty

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Air Cleaners (CI Engine)

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Induction Manifold

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Fuel System- Petrol Engine

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Engine Cylinder

Carburettor

Fuel Filter

Low Pressure Fuel Pump

Fuel Tank

20-35Kpa

OR SU electrical

Chamois leather(moistened withpetrol, will interceptwater, of course

fine grit also)

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A/F ratio

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Carburettor

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Section of Solex carburettor

Diff A/F ratio: Starting Circuit(choke), Idling circuit, Low speed circuit, Partthrottle circuit, Full throttle circuit, Acceleration pump circuit.

The functions of Carburettor:1. To maintain a small reserve of petrol at constant head2. To produce homogeneous A/F mixture by vopourising fuel in the

air suction line3. To supply required quantity of A/F mixture4. To correct the A/F ratio of the mixture according to engine speed

and requirement.

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Fuel System Diesel Engine

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Engine Cylinder

Fuel Injector

FIP( High Pressure Fuel Injection pump)

Fuel Filter (secondary)

Low Pressure Fuel Pump

Fuel Filter ( primary)

Fuel Storage Tank Diesel Primary Fuel filter

Diesel fuel lighter than

impurities

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Diesel- Secondary Fuel Filter

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Fuel Injection Pump ( Diesel Engine)

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Fuel Injection System CI Engine

1. Air Injection 2. Solid Injection/ mechanical injection

Advs:1. Compact and simple

2. Better control of fuelquantityDis Advs:1. Requires very high

accuracy/precision inmanfg.

2. Inferior quality fuelcannot be injected.

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FIP Element

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Ignition Delay-diesel

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Fuel Injector

M lti P i t F l I j ti

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Multi Point Fuel Injection(Petrol)

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Schematic Diagram of Petrol Injection System

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Advantages of MPFI

Better thermal efficiency (due to better mixture control by the ECU Increased volumetric efficiency ( no ventury-no pressure loss inlet manifold Cylinder to cylinder variation in A/F ratio and power developed is minimised

Detonation reduced Better emission control and reduction in pollutants in exhaust gas. Quick response to accn and deceleration Better fuel economy Less engine vibration

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Gasoline Direct Injection (GDI)

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simplified suction manifold Free from icing troubles Quick start and warm up Can operate under very lean A/F

mixture Can have higher CR

Higher power and efficiency Uniform mixture for all cylinders Greater freedom in the choice of

fuel No necessity of induction heating

Advs:

Disadvs:

1. Complicateddesign

2. Higher initialandmaintenancecost

3. Servicing isdifficult.

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CRDI- Common Rail Direct Injection(Diesel engine)

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a) Battery Ignition System

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Ignition System for SI Engine -

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b) Magneto ignition System

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Spark plug

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Governing of IC Engine

Quantity Governing Quality Governing

Hit and Miss Governing

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Electric Vehicle

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Hybrid Vehicle- Series

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Hybrid Vehicle- Parallel

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Appendix

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