lesson 08 - diesel
TRANSCRIPT
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Internal CombustionInternal Combustion
Engines Engines
The DieselThe Diesel
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ObjectivesObjectives
Uses for internal combustionengines
Thermodynamic principlesinvolved
Components and purposes of each
Operation of systems Two stroke engines
Four stroke engines
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The Diesel is a HackerThe Diesel is a Hacker
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Engine UsesEngine Uses
Emergency Diesel Generators(EDG)
Propulsion Certain amphibious landing ships Mine warfare ships Patrol craft
Tug boats Small boats Outboard motors
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T ermo ynam cermo ynam cPrinciplesPrinciples
All internal combustion Open cycle, heated engine
Gasoline (Otto) engine Spark ignition Compresses air-fuel
mixture
Diesel engine Compressed ignition
Compresses air only
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Structural ComponentsStructural Components
Cylinder Block Part of engine
frame that
containscylinders inwhich pistonmoves
Supports liners &head
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Structural ComponentsStructural Components
Cylinder Head/Assembly Serves to admit, confine, and release
fuel/air
Cover to cylinder block
Supports valve train
Crankcase Engine frame section that houses the
crankshaft
Oil sump Reservoir for collecting and holding
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Moving ComponentsMoving Components
Three Groups according to
motion Reciprocating only (pistons andvalves)
Reciprocation & rotary (connecting
rods) Rotary only (crankshafts and
camshafts)
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Moving ComponentsMoving Components Piston
Acted on by combustiongases
Lightweight butstrong/durable
Piston Rings Transfer heat from piston to
cylinder Seal cylinder & distribute
lube oil Piston Pin
Pivot point connectingpiston to connecting rod
Connecting Rod
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Moving ComponentsMoving Components
Crankshaft Combines work done by each piston Drives camshafts, generator, pumps,
etc.
Flywheel Absorbs and releases kinetic energy of
piston strokes -> smoothes rotation of
crankshaft
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Moving ComponentsMoving Components
Valves Intake: open to admit air
to cylinder (with fuel in
Otto cycle) Exhaust: open to allow
gases to be rejected
Camshaft & Cams Used to time the addition
of intake and exhaustvalves
Operates valves via
pushrods & rocker arms
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OperationOperation
Increased pressure of combustiongases acts on piston -> converted
to rotary motion Can be 2 or 4 stroke engines
2-stroke: 1 power stroke per 1
crankshaft rev 4-stroke: 1 power stroke per 2
crankshaft rev
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OperationOperation Engine stroke
A stroke is a single traverse of thecylinder by the piston (from TDC toBDC)
1 revolution of crankshaft = 2 strokesof piston
F S k Di lF St k Di l
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Four-Stroke DieselFour-Stroke Diesel
EngineEngine
Intake stroke Intake valve open, exhaust valve
shut
Piston travels from TDC to BDC
Air drawn in
Compression stroke Intake and exhaust valves shut
Piston travels from BDC to TDC
Temperature and pressure of air
increase
F St D
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Four-Stro e D eseour- ro e eseEngineEngine
Power stroke Intake and exhaust valves shut Fuel injected into cylinder and ignites Piston forced from TDC to BDC
Exhaust stroke Intake valve shut, exhaust valve open
Piston moves from BDC to TDC Combustion gases expelled
F St D
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Four-Stro e D eseour- ro e eseEngineEngine
Strokes Intake
Compression
Power
Exhaust
T St D
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Two-Stro e D esewo- ro e eseEngineEngine
1 power stroke every crankshaftrevolution (vice every two w/ 4-stroke)
Uses pressurized air tosimultaneously supply new air andexpel combustion gases
Scavenging Exhaust valve open, inlet port
exposed Pressurized air enters, expels
combustion gases
T St D
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Two-Stro e D esewo- ro e eseEngineEngine
Compression Intake and exhaust valves shut Piston travels from BDC to TDC Temperature and pressure of air
increase
Power stroke
Intake and exhaust valves shut Fuel injected into cylinder and ignites Piston forced from TDC to BDC
T St D
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Two-Stro e D esewo- ro e eseEngineEngine
Strokes Compression
Power (Intake/Exhaus
t)
kT F S k
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Two vs. Four-StrokeTwo vs. Four-Stroke
EnginesEngines
Two-stroke advantages Higher power to weight ratio
Less complicated valve train Four-stroke advantages
More efficient burning process
As size increases, power-to-weightratio improves
Gaso ne vs D eseaso ne vs ese
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Gaso ne vs. D eseaso ne vs. eseEngineEngine
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Supporting SystemsSupporting Systems
Air system Supplies & removes air/gases
Air supplied at constant pressure byblower/compressor
Fuel System Carburetor: mixes air & fuel in proper
proportion (NOT on diesels)
Fuel injector: sprays fuel in (moreefficient)
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Supporting SystemsSupporting Systems
Ignition system Diesel has compression ignition Gasoline has spark plugs
Cooling system Uses fresh water and/or salt water to
cool
Lubrication system Provide lubrication and cooling
Drive Train Direct or Indirect
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Safety PrecautionsSafety Precautions
Noise
Fuel Flammability
Maintenance Water Issues
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QuestionQuestion
s?s?