4 Stroke Diesel Engine

4 STROKE DIESEL ENGINE

CONTENTINTRODUCTIONHISTORYWORKING OF 4 STROKE DIESEL ENGENEDIAGRAMBASIC COMPONENTS USEDADVANTAGEDISADVANTAGECONCLUSION

BRIEF INTRODUCTION

• A diesel engine is an internal combustion engine.

• It converts gasoline into motion• It is the most common car engine type• It is relatively efficient• It is relatively inexpensive • The engine works on the principle

of diesel cycle

HISTORY Rudolf Christian Karl Diesel (March 18, 1858 – September 29, 1913) was a German inventor and mechanical engineer, famous for the invention of the 4-stroke diesel engine. 

RUDOLPH DIESEL

Working of Four Stroke Diesel Engine

Following are the four strokes:-

1 – Intake/Suction stroke2 – Compression stroke3 – Expansion stroke4 – Exhaust stroke

1. Intake 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 closedand inlet valve will be open to allowing the fresh charge of mixed fuel & air into the cylinder.

2 . 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 inside the cylinder & compression takes place. Hence it is called compression stroke.

3. Power StrokeIn expansion stroke, Both the valves are closed. When piston reaches top of its stroke. the fuel is sprinkled by the Fuel Injector and the fuel mixture is ignited due to high temperature & pressure generated inside the cylinder & push down the piston to BDC. Hence it is known as Power or expansion stroke. The Power generated in this stroke is stored in the flywheel for its furthur utilisation in the other strokes.

4. 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.

P-V Graph of Diesel Engine

P-V Graph of Diesel Engine

BASIC COMPONENTS USED

1. ENGINE BLOCK2. Crankshaft3. Cam shaft4. Cylinder head5. Piston 6. And many more…

DETAILED VIEW OF THE COMPONENTS

1. ENGINE BLOCK– Cast in one piece. The basis for most of the parts

of the engine.– ‘V’ Shape– 2 Sides• Generator Side• Free Side

2. CRANKSHAFT

– Singular costliest item in diesel engine.

– Medium of transforming reciprocating motion to rotary motion.

– Balance weights can be either bolted up or welded.

3. CAM SHAFT– Performs the vital role of opening & closing inlet &

exhaust valves.– Allow timely injection of fuel inside the cylinder.– Usually 3 cams for each cylinder-

2 outer cams for exhaust & inlet valves 1 central cam for fuel injection.

4. CYLINDER HEAD– CH is held on the cylinder liners by 7 hold down

studs.– Subjected to high shock stress & combustion

temperature at the lower face.– Complicated casting where cooling passages are

cored for holding water.– Space had been provided for passage of inlet air &

exhaust gases.– Space for fuel injection nozzles, valve guides &

valve seat.

5. PISTON–Compresses the air to required pressure &

temperature–Receives the thrust of expanding gases &

transmits the force through connecting rod.–With the help of piston rings, prevents

leakage of gas from combustion chamber.

6. SOME OTHER PARTS– PISTON RINGS

• Seal the combustion chamber• Prevent blow by of air & high

temperature combustion gases.– CONNECTING ROD• Connects piston & crank shaft• Medium of converting reciprocating

motion to rotary motion.– LINERS• Forms the wall of the combustion chamber.• Guides the movement of piston.

ADVANTAGES

• More efficient.• More reliable.• More durable.• Release less amount of harmful fumes.• Easily turbo-charged.• Produce minimal carbon monoxide.• Can easily accept synthetic fuels.

CAN ACCEPT SYNTHETIC FUELS

NO HARMFUL EMISSIONS

DISADVANTAGES

• More expensive. • Occasionally servicing can be more costly.• Parts tend to be more expensive.• The cost of diesel at the pump is higher.• Contribute to Greenhouse effect.• Generally more noisy.

EXPENSIVEA BIT NOISY

Let’s Conclude...

• Diesel Engine relies upon compression ignition.• Compression ratio lies b/w 16:1 and 25:1.• Temp. increases to 700C to 900C.• Piston approaches TDC, fuel is injected.• Ignition instantly occurs, causing a rapid increase in

cylinder temperature & pressure.• Piston is driven downward with great force, pushing

on the connecting rod & turning the crankshaft. • Exhaust gases are expelled then.