4 Stroke Engine cycle

http://www.youtube.com/watch?v=4HPV73v7Ub8

Part 1

4 Stroke Engine cycle

A cylinders displacement is the volume of the cylinder when the piston is at BDC.

It is the sum of the displacement of each cylinder.

It is defined as the volume of air/fuel mixture an engine can draw in.

Engine displacement

Engine displacement

Ex: 700 cc (cubic centimetres) 1000 cc = 1 Litre

Example : Vehicle has 4 cylinders : Each cylinder has a volume of

700cc : 700cc X 4 = 2800cc : 2800cc = 2.8 Litre

Engine displacement

Torque is the term used to describe a rotating force.

More torque generally means a car can accelerate faster

Torque is the actual reading of how “hard” and with how much “Force” the engine turns.

Torque

Horsepower: 1 hp = 33,000 lb-ft / min One horsepower is the ability to lift 33000

pounds one foot in one minute The horsepower specification for an engine

tells you how much power the engine can produce. 

Horsepower is the rate at which the engine does work

Horsepower

Formula:

HORSEPOWER = (TORQUE * RPM) / 5252

A engine that makes 300 pound-feet of torque at 4,000 RPM produces

[(300 x 4,000) / 5,252] 228 horsepower at 4,000 RPM

Horsepower calculations

Think about:

Torque being how hard you can pound away on bicycle pedals

Horsepower being how fast you can spin the bicycle pedals.

Torque and Horsepower

Recap What is engine displacement? What is horsepower? What is Torque? What are the different parts of an engine?

http://www.youtube.com/watch?v=60QX5RY_ohQ&feature=related

Part 2

The 4 stroke cycle

Spark plug

Inlet valve

Exhaust valve

Cylinder

Piston

The four-stroke engine

Piston, connecting rod, crankshaft Is a can-shaped part closely fitted inside the

cylinder. Piston rings consist of compression rings

and oil rings. Crankshaft takes the up-down motion of the

piston and convertors it to a rotation motion Connecting rod connects the piston to the

crankshaft.

The 4 Stroke engine cycle consist of these: 1) Intake 180degree2) Compression 180 degree3) Power/ Combustion 180 degree4) Exhaust 180 degree

Total engine revolution 720 degree One complete engine cycle consists of 4 engine

strokes.

What is the 4 Stroke cycle?

The Intake Stroke consist of the piston travelling down.

Intake valves are open to allow Air/Fuel mixture to come into the combustion chamber.

Intake

Intake plastic ducts Intake manifolds

Intake system

Intake system

- Fuel injectors are electronically controlled valves that spray fuel to mix with air.

- Creating that air fuel mixture-

Intake system

It is an electrical device that fits into the cylinder head and ignites air fuel mixtures.

Spark plugs

Inlet valve open

INTAKE STROKE

The four-stroke engine

Exhaust valve closed

Inlet valve open

Piston downINTAKE STROKE

The four-stroke engine

Exhaust valve closed

Inlet valve open

Piston downINTAKE STROKE

The four-stroke engine

Fuel in

Exhaust valve closed

Inlet valve open

Piston downINTAKE STROKE

The four-stroke engine

Fuel in

Exhaust valve closed

What is the purpose of the intake system? What is the purpose of the spark plug? What is the purpose of the fuel injector? What is happening during the intake stroke?

Recap

Part 3

http://www.youtube.com/watch?v=q4Bk2TJJ6TM

4 Stroke engine

Compression stroke consist of the piston travelling back up.

Both intake and exhaust valves are closed Air fuel mixture is now being compressed

Compression

Inlet valve closed

COMPRESSION STROKE

The four-stroke engine

Piston up

Exhaust valve closed

Inlet valve closed

COMPRESSION STROKE

The four-stroke engine

Piston up

Exhaust valve closed

Inlet valve closed

COMPRESSION STROKE

The four-stroke engine

Piston up

Exhaust valve closed

The piston is now at the TDC Spark plug ignites, creating a spark that

ignites the compressed air fuel mixture. Explosion is created and the piston is forced

back down. Hence the Power stroke Both valves are still closed

Combustion/Power

Inlet valve closed

POWER STROKE

The four-stroke engine

BANG

Exhaust valve closed

Inlet valve closed

POWER STROKE

The four-stroke engine

Piston downpowerfully

Exhaust valve closed

Inlet valve closed

POWER STROKE

The four-stroke engine

Piston downpowerfully

Exhaust valve closed

Inlet valve closed

POWER STROKE

The four-stroke engine

Exhaust valve closed

Exhaust stroke the piston is travelling up Exhaust valve is open Intake valve is Closed Exhaust gases being pushed out by piston

Exhaust

Inlet valve closed

EXHAUST STROKE

The four-stroke engine

Exhaust valve closed

Inlet valve closed

EXHAUST STROKE

The four-stroke engine

Exhaust valve open

Piston up

Exhaust gasesout

Inlet valve closed

EXHAUST STROKE

The four-stroke engine

Exhaust valve open

Piston up

Exhaust gasesout

Inlet valve open

INTAKE STROKE

The four-stroke engine

Exhaust valve closed

And so the cycle

continues!!

Exhaust system The exhaust system is needed to provide a

pathway for exhaust fumes to be filtered and to reduce noise.

Exhaust manifold Catalytic convertor Muffler

Recap- What is the purpose of the compression

stroke and what is happening- What is the purpose of the power stroke and

what is happening?- What is happening during the exhaust

stroke? What is the purpose of the exhaust

system?

http://www.youtube.com/watch?v=IYWUWMmimjQ&feature=related

http://videos.howstuffworks.com/auto/car-parts-videos-playlist.htm#video-30374

Video of 4 Stroke cycle

QUIZ

http://www.youtube.com/watch?v=YB_JCUw9SoU&feature=related

4 Stroke cycle