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Four stroke_ two stroke_ diesel_ wankel lesson

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           1
Four Stroke, Two Stroke
Diesel, & Wankel Engine
 Theory and Operation




                          2
        Four Stroke, Two Stroke,
        Diesel, & Wankel Theory
                  Presentation Outline

 1.0   Four Stroke Engine Theory
  •   Internal combustion principles
  •   Valve operation
  •   Four cycles
  •   Valve timing

 2.0   Two Stroke Engine Theory
  •   Two cycle operation
  •   Lubrication
  •   Variations
  •   Advantages/ limitations            more...
                                                   3
3.0   Diesel Engine Theory
  •Operation
  •Variations
  •Advantages/limitations

4.0   Wankel Engine Theory
  •Operation
  •Variations
  •Advantages/limitations




                              4
   1.0 Four Stroke Engine
           Theory
 Intake
 Compression
 Power
 Exhaust




                            5
Intake Stroke




                6
       Compression Stroke




Valves closed




                            7
           Power Stroke




Valves closed




                          8
Exhaust StrokValve Timing
        Diagram




                            9
   2.0 Two Stroke Engine
          Theory
 Upstroke
 Down stroke




                           10
2 Stroke             Compression
Up Stroke            occurs



 Transfer
 Port


    Crank
    Case
                     Reed Valve


        Carburetor
                                   11
2 Stroke
Down Stroke                 Intake
                            Power
                            Exhaust
                            Occurs
Transfer Port




                   +
                       Reed Valve


          Carburetor
                                      12
             Fuel Mix
 Uses   a premix of gas and oil
 Oil injectors used in some
 Normal mixes range from 16:1 to 50:1
 Typical “hot” engines 16:1
 Typical “cool engine” 50:1
 CHECK OWNERS MANUAL !!!



                                         13
 Advantage of Two Strokes
 Runs  in any position
 More horsepower for size
 Fewer moving parts
 Lighter




                             14
 Limitations of Two Strokes
 Uses  more fuel than four strokes
 Fuel and oil must be mixed
 Plugs foul easily
 Poor emissions




                                      15
3.0 Diesel Engine Theory




                           16
          Introduction
• Invented by Rudolf Diesel between
  1892 and 1893
• Internal Combustion Engine
• Reciprocating Engine
• Intermittent Combustion Engine
• Utilizes liquid fuel
• Compression Ignition vs. Spark
  Ignition
• Heavy Duty Applications
                                      17
 Diesel Compression Ratio
 20:1up to 25:1 common
 Needed to ignite fuel
 No spark plugs




                            18
      Compression Ratios
 “Squeeze”   on air/fuel mixture before
  combustion
 Efficiency increases with higher CR
 About 9:1 on gas autos
 17:1 to 24:1 for diesel engines
 About 24:1 CR max:
  • too high compression for starting
  • limiting strength of materials
  • power loss- leakage around valves
                                           19
     Advantages of the Diesel
             Engine
•   High reliability
•   Low fuel cost
•   High power / lb. of engine
•   Low fuel consumption
•   Low fire hazard
•   High torque at low RPM
•   Greater heat efficiency- 30% (25% gas)
•   Longer service intervals

                                             20
   Disadvantages of Diesel
           Power
 Expensive   to repair
 Hard starting in cold weather
 Higher initial cost




                                  21
Gasoline and Diesel Engine
       Comparison
              Gasoline  power
               stroke = 460 psi;
               Diesel = 1200psi
              Diesel heat
               efficiency about
               5% higher than
               gasoline



                                   22
        Induction System

                       Air Only


Injection
Line
                       High Pressure
                       Injection Spray
 Injector Delivering
        Fuel




                                         23
               Glow Plugs
 Resistance   unit to heat cold engines
 Installed in cylinder head, sometimes in
  special pre-combustion chamber
 Some use intake heaters
 In addition, block heaters for cold weather




                                                24
Typical Diesel Engine

                        25
4.0 Wankel Engine Theory




                           26
         History of RCE
  (Rotary Combustion Engines)

 1924 - Wankel’s idea for RCE
 1933 - patent was applied
 1936 - patent received
 1957 - engine runs




                                 27
              Epitrochoidal Bore
                                   Apex Seal

Intake
Port

 Rotor                             Spark
                                   Plugs


 Exhaust
 Port


One of Three Chambers

                                               28
     Rotor and Apex Seals
 Sometimes    called   Apex Seal Location
  a “Rotary Piston”
 Receives power
  impulse from fuel
  air mixture
 Rotor has three
  faces
 Apex seals at
  tips-like rings
                                             29
         Epitrochoidal Bore
               E-Bore
 Same   purpose as
  the cylinder walls
  of the piston
  engine
 Epitrochoid curve,
  generated by
  rolling a circle
  around another
  circle               Basic shape of epitrochoid
                       curve
                                                    30
Rotors


         Eccentric
         Shaft




E-Bore
                     31
32
Advantages and Limitations
 Fewer  moving parts
 Single motion allows smoother
  running
 Compact engine, allows for more
  space
 Few manufacturers produce this
  engine any longer

                                    37
         Summery (Cont)
 What are the major differences in
 parts between a 2 stroke & 4 stroke?
  • Ports vs. Valves
  • Reed valve vs. Valves
 How is the fuel ignited in a deisel
 engine?
  • Compression


                                        39
         Summery (Cont)
    Rotory (Wankel) engine uses
 The
 what type of bore?
  • E- Bore
 Whatact like rings in a rotory
 engine?
  • Apex seals
    can be __________, while water
 Air
 can not?
  • Compressed
                                     40
The End




          41

				
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