Engines

1
Engines

• Control Power
• CVHS

2
Introduction

• We will be examining several types of engine
  converters that are commonly used
• Many are used in the Transportation sector
• We call them Heat Engines because
• convert thermal energy from fuel to mechanical
  energy for motion
• Classifications are based on
• location of combustion, type of combustion, and
  type of internal motion

3
Common Classifications

• IC or ICE
• combustion is internal
• combustion directly touches the parts that must
  be moved
• example car engine
• EC or ECE
• combustion is external
• example boiler (steam engine)

4
Common Classifications

• Intermittent Combustion Engine
• combustion starts and stops many times
• examples car engines - gas and diesel
• Continuous Combustion Engine
• example rocket engine
• Reciprocating Engine
• classification based on internal part motion
• examples gas and diesel engines

5
Common Classifications

• Rotary Engines
• another parts motion
  classification
• internal parts have a
  continuous rotation movement
• examples Wankel and Turbine engines
• Others Classifications
• Cycles, Cooling Sys, Fuel Sys, Ignition Sys

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Heat Engine Parts and Systems

• Cylinder Block
• Foundation
• All other components are attached
  to it
• Cylinders
• internal holes in the block (combustion chambers)
• Autos 2, 3, 4, 5, 6, 8,10 ,12Autos 3, 4, 6, 8,
  12
• Cylinder Head
• houses the valves, ports and spark plugs for the
  engine
• Valves and Ports
• purpose is to allow air and fuel to enter and
  leave the combustion chamber

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Heat Engine Parts and Systems

• Pistons
• the round piece that slides up
  and down within the
  cylinder
• Connecting Rod and Crankshaft
• CR is attached from the bottom of the piston and
  attaches to the crankshaft
• the crankshaft converts reciprocating
  motion to rotary
• Combustion Chamber
• the area inside the Cylinder
  Head and Block

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Heat Engine Parts
and Systems

• Camshaft
• the mechanism used to open
  the valves at the right
  times
• it is driven by the crankshaft which is connected
  to the connecting rod (timed to the crankshaft)
• may be mounted in the block or on top of the
  block (OHC - Overhead camshaft) (DOHC - Dual
  Overhead Camshaft)

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Heat Engine Parts and Systems

• Flywheel
• connected to the end of the crankshaft to smooth
  out any intermittent motion (remember we have
  intermittent combustion)
• utilize Newtons Law
• An object in motion tends to remain in motion,
  whereas an object at rest tends to remain at rest

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Heat Engine Parts and Systems

• Carburetor/Fuel Injection
• mixes the air and fuel in the right proportion

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Engine Systems

• Cooling liquid and air - keep temp constant
• Fuel monitor and control the feed
• Lubrication reduce friction
• Ignition providing the spark for combustion
• Starting crank (battery dc starter motor)
• Charging replenish the battery
• Air/Exhaust feed air in an out
• Computer Controlled to aid - precision of sys.
• Fuel, ignition, etc.
• Pollution Control environmental

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Combustion Requirements

• 1) AIR
• 2) FUEL
• 3) SPARK
• 4) TIMING
• 5) COMPRESSION

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Bore Stroke

• Bore Stroke help determine the size
• Bore - diameter of the cylinder
• Stroke - distance the piston travels from
  TDC to BDC
• determined by design of the crankshaft
• center of the crankshaft to the center of the
  crankpin multiplied by 2 the stroke distance

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Four Stroke Engine Design

• One of the most popular reciprocating-type heat
  engines
• Intake piston moves downward with intake valve
  open
• Compression piston moving upward, all valves are
  closed
• Power after the spark,
  power occurs downward
• Exhaust as the piston
  moves upward
  again,
  exhaust valves open

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Two-Cycle Engine Design

• Does not use standard valves like the 4-cycle
• Oil is added to the Air-Fuel mixture because
  there is no oil in the crankcase as with the
  4-cycle engine design
• the oil acts as a lubricant
• Compression Stroke up
• creates a vacuum and pulls in the fuel/oil
  mixture into the combustion chamber (Crankshaft)
• Ignition just before TDC, crankcase full, reed
  valve closed
• Power Stroke down
• exhaust is vented out by pressure on the fuel in
  the combustion chamber from the piston

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Advantages Disadvantages of 2-Stroke

• ADV
• Very responsive (power pulse every rev.)
• Usually lighter than 4-cycle engines, fewer parts
• Can be operated at varying angles of operation
• no crankcase that holds oil
• DISADV
• Not as efficient as 4 stroke
• Not as durable

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Diesel Engine Design

• Considered a 4 cycle, IC (can also have 2 cycle)
• Compression rather than spark ignition
• Glow plug and block heaters used to
  pre-warm fuel and
  engine on cold starts
• No carburetor (fuel injection)
• air enters on the intake stroke
• Fuel is injected during compression
• Extreme pressure (diesel engines
  have very high compression
  ratios)
  heat ignite fuel

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Rotary (Wankel)

• MAZDA
• Most popular during the 1970s
• Not Reciprocating
• Rotors instead of Pistons
• No valves (only the intake and exhaust ports)
• Intermittent combustion, spark ignition, rotary
  design
• Few moving parts extremely high revs.