+ Lower thermal efficiency ( some fuel goes out with exhaust gases) + More polluted ( some fuel is not. burned).[r]
(1)2 stroke-engines
Presented by:
(2)(3)2- stroke engine
Introduction Structure
Operation
Differences between 2- stroke engine
and 4- stroke engine
(4)2-stroke engine
Lawn and garden equipment (chain
saws, leaf blowers, trimmers)
Dirt bikes Mopeds Jet skis
Small outboard motors
(5)(6)operation
2 strokes : compression stroke and combustion stroke
(7)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
(8)operation
1st stroke: intake
and compression - As the piston nears
the top of the
stroke, the ignition system ignites the charge in the
(9)operation
1st stroke: intake and
compression
- Piston moves down, the compressed
mixture in the
crankcase escapes around the piston into the main
cylinder, exhaust
(10)operation
2nd stroke: power and
exhaust
- Piston moves up, the mixture is ignited
(11)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
(12)(13)