tieng anh co khi

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2 stroke-engines

Presented by:

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2- stroke engine

 Introduction
 Structure

 Operation

 Differences between 2- stroke engine

and 4- stroke engine

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2-stroke engine

 Lawn and garden equipment (chain

saws, leaf blowers, trimmers)

 Dirt bikes
 Mopeds
 Jet skis

 Small outboard motors

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operation

2 strokes : compression stroke and
combustion stroke

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operation

 1st stroke: intake and

compression

- Piston rises, reed
valve opens and
mixture sucks into
the crankcase

- Air fuel mixture
already in the
cylinder is

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operation

 1st stroke: intake

and compression
- As the piston nears

the top of the

stroke, the ignition
system ignites the
charge in the

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operation

 1st stroke: intake and

compression

- Piston moves down,
the compressed

mixture in the

crankcase escapes
around the piston
into the main

cylinder, exhaust

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operation

 2nd stroke: power and

exhaust

- Piston moves up, the
mixture is ignited

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differences

Four-stroke engines

+

One power stroke in two
revolutions

+More bulkier with valve
mechanism

+ More expensive production
and maintenance cost

+ Less cooling and lubricating
requirements

+ Higher thermal efficiency
+ Less polluted

 Two-stroke engines

+ One power stroke in one
revolution

+ Lighter and more compact

+ Less production and maintenance
cost

+ More cooling and lubricating
requirements ( more power
strokes)

+ Lower thermal efficiency ( some
fuel goes out with exhaust gases)
+ More polluted ( some fuel is not

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