FOUR STROKE PETROL ENGINE

GROUP MEMBERSO MUHAMMAD ALI

13ME22O MUHAMMAD AKHTAR

13ME42O MUHAMMAD WASEEM

13ME16O USMAN SAJID

13ME40

CONTENTS:1. INTRODUCTION OF FOUR STROKE PETROL

ENGINE2. OTTO CYCLE3. WORKING OF FOUR STROKE PETROL ENGINE4. THERMODYNAMIC PROCESS ANALYSIS5. ADVANTAGES AND DISADVANTAGES OF FOUR

STOKE PETROL ENGINE6. APPLICATIONS OF FOUR STROKE PETROL

ENGINE7. FOUR STROKE LUBRICATION

INTRODUCTION OF FOUR STROKE ENGINE

O Engine: An engine is motor which converts chemical energy into mechanical energy

O Fuel/petrol engine: A petrol engine (known as a gasoline engine in North America) is an internal

combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels.

O Four stroke engine: A four-stroke engine (also known as four-cycle) is an internal combustion

engine in which the piston completes four separate strokes which comprise a single thermodynamic cycle. A stroke refers to the full travel of the piston along the cylinder, in either direction.

OTTO CYCLEIn 1862 a German engineer Nikolaus Augustus Otto began experimenting with different kinds of engines.

His first experiment was conducted on a 4-stroke engine. 10 years later he introduced to the world the Otto engine.

The 4-stroke engine consists of a 4-stroke cycle better known as the Otto cycle.

(1832-1891)

OTTO CYCLEEach movement of the cylinder up or down the cylinder is one stroke of

the four stroke combustion cycle or Otto cycle.

The four stroke cycle consists of

- induction stroke

- compression stroke

- ignition/power stroke

- exhaust stroke

A single cycle requires two revolutions of the crankshaft to complete.

WORKING OF FOUR STROKE PETROL ENGINE

O INTAKE/SUCTION STROKE:In suction stroke piston starts at Top Dead Center (TDC) of the cylinder and moves to the

Bottom Dead Center (BDC). Outlet valve will be closed and inlet valve will be open to allowing the fresh charge of mixed fuel & air into the cylinder.

O COMPRESSION STROKE:In compression stroke,Once piston reaches BDC & moves back TDC,inlet valve will be

closed,As the piston moves towards TDC,It compress air fuel mixture inside the cylinder & compression takes place,Hence it is called compression stroke.

O EXPANSION/POWER STROKE:In expansion stroke,Both the valves are closed,When piston reaches top of its stroke the

fuel mixture is ignited by spark plug due to spark high temperature & pressure generated inside the cylinder & push down the piston to BDC,Hence it is known as expansion stroke.

O EXHAUST STROKE:

In this stroke exhaust valve is opened,when piston reaches to BDC & moves to upward.Piston pushes out the burnt gases to the atmosphere through the exhaust valve. Hence called exhaust stroke & the engine is ready to begin the cycle again.

THERMODYNAMIC PROCESS ANALYSIS

ADVANTAGES OF FOUR STROKE PETROL ENGINE:

O Less fuel consumption.O Thermal efficiency is more.O More volumetric efficiency.O Less wear and tear.

DISADVANTAGES OF FOUR STROKE PETROL ENGINE:

O More components.O Separate valve mechanism

is required.O More cost.O More complicated design.

APPLICATIONS OF FOUR STROKE PETROL ENGINE:

O The four stroke version is generally used for larger applications and is the most common type of engine used in automobiles today.

O This type of engine is an ingenious and practical design that has powered millions of vehicles. It produces a large amount of power in an efficient and effective manner. It also generally produces less pollution and lasts longer than a two stroke engine. The engine was created by Nikolas Otto in the mid 1800s, and in his honor, it's sometimes known as the Otto Engine. The four main strokes or steps that make up the cycle are intake, compression, combustion, and exhaust, which is sometimes called the Otto cycle.

LUBRICATION OF FOUR STROKE PETROL ENGINE:

O Four-stroke engines are lubricated by oil held in an oil sump. The oil is distributed through the engine by splash lubrication or a pressurized lubrication pump system; these systems may be used alone or together.