Docstoc

Internal Combustion Engines

Document Sample
Internal Combustion Engines Powered By Docstoc
					Internal Combustion
Engines

Engine Classification
Small Engine Development
Energy Conservation Principles
Small Engine History
Competencies
 Explain the classification “small engine” and discuss the
    main small engine types
   Describe types of cylinder design and cooling systems
   Explain small engine development history
   Explain energy conversion principles that apply to small
    engines
   Explain heat transfer
   List the common energy conversion calculations
   Explain the chemistry of fuel combustion in small engines
   Describe the small engine industry
Small Engines

 Internal combustion engine
     Converts potential chemical (heat) energy
      into mechanical energy
        Example   of an internal combustion engine:
             Lawnmower engine
             Automobile engine
        Example   of an external combustion engine:
             Steam engine
                 Locomotive
Small Engines

 Rated up to 25 horsepower (HP) average
    Technology increasing with engines rated at 35 HP
    HP not used as an accurate measurement of power
     due to difference in engine speeds of various
     engines
 Spark ignition or compression
    Spark example:
       Gas
       Alcohol
    Compression example:
       Diesel
Small Engines

 Four-stroke or two-stroke cycle
     Four-stroke application found in:
        Lawnmowers

        Outboard engines
        Generators

     Two-stroke application found in:
        Chainsaws

        Trimmers
Engine Design

 One, two, three or four cylinders (small
  engines)
 Cylinder orientation
     vertical
     horizontal
     slanted
        Allows   for more compact space
 Cylinder configuration
     V, horizontally-opposed, or in-line
 SMALL ENGINE
 DEVELOPMENT
1680         Gunpowder           Christian Huygens

1698        Savery Pump           Thomas Savery

1712     Newcomen Steam          Thomas Newcomen

1763     Watt Double-Acting         James Watt
               Steam
1801    Coal Gas with Electric     Eugene Lebon
              Ignition
1859   Pre-Mixed Coal Gas and      Etienne Lenoir
                 Air
1862          Gasoline             Nikolaus Otto

1876     Four-Stroke Cycle         Nikolaus Otto
             Gasoline
1892           Diesel              Rudolf Diesel
Development History

 Gunpowder Engine
     Created by Christian Huygens (HY-GEN)
      in 1680
     Consisted of a tube sealed on one end
      with a close-fitting slug located inside
        Tubefilled with volume of gunpowder
        Gunpowder compacted then ignited
Development History

 Savery Pump
     Created by Thomas Savery in 1698
     Designed to pump water from underground
      mines
        Utilizedlow pressure generated by
         condensed steam to fill a vessel with water
        Pressurized the vessel with steam to force
         water to surface
Development History

 Newcomen Steam
 Engine
     Created by Thomas
      Newcomen in 1712
     Used to pump water
      from mines
     Utilizes many same
      components found in
      engines today
Development History

 Newcomen Steam
 Engine
     Piston located inside
      cylinder
     Valves
     Boiler
     Pivot arm
     Uses condensed
      steam & atmospheric
      pressure to operate
Development History

 Watt Double-Acting
  Steam Engine
      Created by James
       Watt in 1763
      Made significant
       improvements that
       greatly increased
       efficiency of
       Newcomen steam
       engine
Development History

 Watt Double-Acting
  Steam Engine
      Incorporation of an
       outside condenser

         Eliminated thermal
          cycles and used
          steam directly
      Created a valve
       system
         Allowed piston to
          be pushed by
          steam in both
          directions
Development History

 Coal Gas with Electric Ignition
     Created by Eugene Lebon in 1801
     Mixed coal gas and air
Development History

 Gasoline Engine
      Created by Nikolaus Otto
       in 1862
      Engine efficiency
       improved when air-fuel
       mixture was compressed
       before ignition
      Combustion in engine
       forced piston up the
       cylinder
      Introduced four-stroke
       engine in 1876
Development History

 Diesel Engine
     Created by Rudolf Diesel in 1892
        High compression produces superheated air
         in combustion chamber
        Fuel introduced ignites on contact

     First experiments utilized coal dust as a
      fuel source
Energy Conversion Principles

 Small engines convert potential (gas)
  energy into kinetic (energy of motion)
  energy
     Example: flywheel
 All internal combustion engines operate
  utilizing basic principles of heat, force,
  pressure, torque, work, power, and
  chemistry
Heat Transfer

   Conduction is heat transfer from atom
    to atom via molecules in direct contact
       Heat from piston to oil to engine to air
   Convection is heat transferred by
    currents in a fluid
       Heat to fluid to cooling system
   Radiation is heat transfer that occurs
    as radiant energy without a material
    carrier
Energy Conversion
Calculations
 Temperature is the intensity of heat
      °C = (°F – 32) / 1.8
      °F = (1.8 * °C) / +32
 Pressure is a force acting on a unit of
  area
      Pressure = force / area
Energy Conversion
Calculations
 Torque is a force acting on a
  perpendicular radial distance from a
  point of rotation
     Torque = force * radius
 Work is the movement of an object by a
  constant force (movement of one object
  to another)
     Work = force * distance
Energy Conversion
Calculations
 Power is the rate at which work is done
     Power = work / time
 Horsepower (HP) is a measure of power
  equal to 76 Watts or 33,000 lb-ft per in
     HP = work / (time X 33,000)
 Higher the torque, the higher the power
  of the engine
Combustion Chemistry

 Combining of hydrocarbon fuel with
  oxygen
 A chemical reaction between the
  hydrocarbon molecule and atmospheric
  oxygen combining at ignition
  temperature causes an exchange of
  elements that releases heat energy
Review

 In a typical small engine, approximately
  what percent of the energy released is
  converted into useful work?
     Approximately 30% of the energy is
      converted into useful work
 What is horsepower?
     Horsepower is a unit of power equal to
      33,000 lb-ft per min

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:14
posted:1/6/2012
language:Latin
pages:23