Internal Combustion Engines The Diesel

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Internal Combustion Engines The Diesel
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Objectives

• Uses for internal combustion engines
• Thermodynamic principles involved
• Components and purposes of each
• Operation of systems
• Two stroke engines
• Four stroke engines

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The Diesel is a Hacker
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Engine 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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Thermodynamic Principles

• 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 Components

• Cylinder Block
• Part of engine frame that contains cylinders in
  which piston moves
• Supports liners head

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Structural 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 lube oil

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Moving Components

• Three Groups according to motion
• Reciprocating only (pistons and valves)
• Reciprocation rotary (connecting rods)
• Rotary only (crankshafts and camshafts)

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Moving Components

• Piston
• Acted on by combustion gases
• Lightweight but strong/durable
• Piston Rings
• Transfer heat from piston to cylinder
• Seal cylinder distribute lube oil
• Piston Pin
• Pivot point connecting piston to connecting rod
• Connecting Rod
• Connects piston crankshaft
• reciprocating rotating motion

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Moving Components

• Crankshaft
• Combines work done by each piston
• Drives camshafts, generator, pumps, etc.
• Flywheel
• Absorbs and releases kinetic energy of piston
  strokes -gt smoothes rotation of crankshaft

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Moving 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 exhaust
  valves
• Operates valves via pushrods rocker arms

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Operation

• Increased pressure of combustion gases acts on
  piston -gt 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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Operation

• Engine stroke
• A stroke is a single traverse of the cylinder by
  the piston (from TDC to BDC)
• 1 revolution of crankshaft 2 strokes of piston

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Four-Stroke Diesel Engine

• 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

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Four-Stroke Diesel Engine

• 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

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Four-Stroke Diesel Engine

• Strokes
• Intake
• Compression
• Power
• Exhaust

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Two-Stroke Diesel Engine

• 1 power stroke every crankshaft revolution (vice
  every two w/ 4-stroke)
• Uses pressurized air to simultaneously supply new
  air and expel combustion gases
• Scavenging
• Exhaust valve open, inlet port exposed
• Pressurized air enters, expels combustion gases
• Piston near BDC

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Two-Stroke Diesel Engine

• 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

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Two-Stroke Diesel Engine

• Strokes
• Compression
• Power
• (Intake/Exhaust)

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Two vs. Four-Stroke Engines

• Two-stroke advantages
• Higher power to weight ratio
• Less complicated valve train
• Four-stroke advantages
• More efficient burning process
• As size increases, power-to-weight ratio improves

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Gasoline vs. Diesel Engine
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Supporting Systems

• Air system
• Supplies removes air/gases
• Air supplied at constant pressure by
  blower/compressor
• Fuel System
• Carburetor mixes air fuel in proper proportion
  (NOT on diesels)
• Fuel injector sprays fuel in (more efficient)

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Supporting 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 Precautions

• Noise
• Fuel Flammability
• Maintenance
• Water Issues

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Questions?