370 likes | 566 Views
Start. Four Stroke, Two Stroke Diesel, & Wankel Engine Theory and Operation. 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
E N D
Four Stroke, Two StrokeDiesel, & Wankel Engine Theory and Operation
Four Stroke, Two Stroke,Diesel, & Wankel TheoryPresentation 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...
3.0 Diesel Engine Theory • Operation • Variations • Advantages/limitations • 4.0 Wankel Engine Theory • Operation • Variations • Advantages/limitations
1.0 Four Stroke Engine Theory • Intake • Compression • Power • Exhaust
Compression Stroke Valves closed
Power Stroke Valves closed
2.0 Two Stroke Engine Theory • Up stroke • Down stroke
2 Stroke Up Stroke Compression occurs Transfer Port Crank Case Reed Valve Carburetor
2 Stroke Down Stroke Intake Power Exhaust Occurs Transfer Port + Reed Valve Carburetor
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 !!!
Advantage of Two Strokes • Runs in any position • More horsepower for size • Fewer moving parts • Lighter
Limitations of Two Strokes • Uses more fuel than four strokes • Fuel and oil must be mixed • Plugs foul easily • Poor emissions
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
Diesel Compression Ratio • 20:1 up to 25:1 common • Needed to ignite fuel • No spark plugs
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
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
Disadvantages of Diesel Power • Expensive to repair • Hard starting in cold weather • Higher initial cost
Gasoline and Diesel Engine Comparison • Gasoline power stroke = 460 psi; Diesel = 1200psi • Diesel heat efficiency about 5% higher than gasoline
Air Only Injection Line High Pressure Injection Spray Injector Delivering Fuel Induction System
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 Glow Plugs
History of RCE(Rotary Combustion Engines) • 1924 - Wankel’s idea for RCE • 1933 - patent was applied • 1936 - patent received • 1957 - engine runs
Epitrochoidal Bore Apex Seal Intake Port Rotor Spark Plugs Exhaust Port One of Three Chambers
Sometimes called a “Rotary Piston” Receives power impulse from fuel air mixture Rotor has three faces Apex seals at tips-like rings Rotor and Apex Seals Apex Seal Location
Same purpose as the cylinder walls of the piston engine Epitrochoid curve, generated by rolling a circle around another circle Epitrochoidal BoreE-Bore Basic shape of epitrochoid curve
Rotors Eccentric Shaft E-Bore
Advantages and Limitations • Fewer moving parts • Single motion allows smoother running • Compact engine, allows for more space • Few manufacturers produce this engine any longer
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
Summery (Cont) • The Rotory (Wankel) engine uses what type of bore? • E- Bore • What act like rings in a rotory engine? • Apex seals • Air can be __________, while water can not? • Compressed