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Engine.ppt - 1 of 20
Product Dissection 04/07/98
Engine Dissection
You are dissecting a 3.5 HP single cylinder, 4 cycle engine, made by Briggs and Stratton in Milwaukee, Wisconsin
These engines are typically used in lawn mowers, snow blowers, go-carts, etc
(ref. 2, Used by permission of Briggs and Statton, ©1992, all rights reserved)
Engine.ppt - 2 of 20
Product Dissection 04/07/98
Engine Module Contentsn Referencesn Historyn Engine Classificationsn Complementary Technologiesn Engine Operation Principlesn Fuel Delivery (carburetors and fuel injection)n Ignition Systemsn Manufacture and Materials Issues (under construction)
Engine.ppt - 3 of 20
Product Dissection 04/07/98
References1) “Why Internal Combustion ?”, Rudi Volti, Invention and
Technology, Fall 1990, pp 42-472) Briggs and Stratton Service and Repair Instructions for
single cylinder 4-cycle engines, 19923) Internal Combustion Engines and Air Pollution, Edward
Obert, Intext Education Publishers, New York, 19734) Introduction to Internal Combustion Engines, Richard
Stone, Macmillan, 1985.
Engine.ppt - 4 of 20
Product Dissection 04/07/98
Classification of Engines
n External vs Internal Combustionn Spark Ignition SI or Compression Ignition CIn Configurationn Valve Locationn 2 Stroke or 4 Stroke
Engine.ppt - 5 of 20
Product Dissection 04/07/98
Engine Configurations
Radial (Aircraft)
V(Automobile)
In Line(Automobile)
Horizontally Opposed (Subaru)
Opposed Piston (crankshafts
geared together)
Engine.ppt - 6 of 20
Product Dissection 04/07/98
Valve Location
L Head(Briggs)
I Head(typical automobile engine)
Advantages:
Disadvantages:
Engine.ppt - 7 of 20
Product Dissection 04/07/98
History of IC Engines
1860 Lenoir’s engine (a converted steam engine) combusted natural gas in a double acting piston, using electric ignition
Engine.ppt - 8 of 20
Product Dissection 04/07/98
History - continuedn 1876 Nikolaus Otto patented the 4 cycle engine, it
used gaseous fueln 1882 Gottlieb Daimler, an engineer for Daimler, left to
work on his own engine. His 1889 twin cylinder V was the first engine to be produced in quantities. Used liquid fuel and Venturi type carburetor, engine was named “Mercedes” after the daughter of his major distributor
n 1893 Rudolf Diesel built successful CI engine which was 26% efficient (double the efficiency of any other engine of its time)
Engine.ppt - 9 of 20
Product Dissection 04/07/98
Complementary Technologies for IC Engine-powered Automobilesn Pneumatic tires (1888, Dunlop)n Cheap liquid fuels (Oil industry born in PA 1859) n Venturi effect carburetor (1892, Willi Maybach)n Variable mechanical transmission (primitive type by
Levassor, 1891)n Electric starter (Kettering 1912)
Engine.ppt - 10 of 20
Product Dissection 04/07/98
Parts of an IC Engine
CROSS SECTION OF OVERHEAD VALVE FOUR CYCLE SI ENGINE
Name as many parts as you can
Engine.ppt - 11 of 20
Product Dissection 04/07/98
Parts of an IC Engine
Air cleaner
Choke
Throttle
Intake manifold
Exhaust manifold
Piston ringsPiston
Wrist pinCylinder blockConnecting rod
Oil gallery to pistonOil gallery to head
CrankcaseCrankpin
Crankshaft
Cylinder head
Breather cap
Rocker armValve spring
Valve guidePushrod
Sparkplug
Combustion chamber
TappetDipstickCamCamshaft
Water jacketWet liner
Connecting rod bearing
Main bearing
Oil pan or sumpIf you scored:25 - 32 You are a certified Gear Head15 - 24 Change your own oil10 - 14 You really need this class
<10 Take your car to “Jiffy Lube”
Engine.ppt - 12 of 20
Product Dissection 04/07/98
4 Cycle Process
Intake StrokeIntake valve opens,
admitting fuel and air.Exhaust valve closed
for most of stroke
Compression StrokeBoth valves closed,Fuel/air mixture is
compressed by rising piston. Spark ignitesmixture near end of
stroke.
IntakeManifold
Spark PlugCylinder
Piston
Connecting Rod Crank
Power StrokeFuel-air mixture burns,increasing temperature
and pressure, expansionof combustion gases
drives piston down. Bothvalves closed - exhaust valve opens near end
of stroke
1 2 3 4
Exhaust StrokeExhaust valve open,exhaust products are
displaced from cylinder.Intake valve opens near end of stroke.
Crankcase
ExhaustManifold
Exhaust ValveIntake Valve
Engine.ppt - 13 of 20
Product Dissection 04/07/98
Briggs Engine - Intake
Engine.ppt - 14 of 20
Product Dissection 04/07/98
Compression
Engine.ppt - 15 of 20
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Power Stroke
Engine.ppt - 16 of 20
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Exhaust Stroke
Engine.ppt - 17 of 20
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2 Stroke Process
Compression(ports closed)Air Taken Into
Crankcase
Combustion(ports closed)
Exhaust(intake port closed)
Air compressed in crankcase
Scavengingand Intake
(ports open)
Engine.ppt - 18 of 20
Product Dissection 04/07/98
Rotary “Wankel” Engine
Ref. Internal combustion engines and air pollution, E. F. Obert
Engine.ppt - 19 of 20
Product Dissection 04/07/98
Venturi-type Carburetor
P+1/2 ρV2 = ConstantBernoulli Effect:
Ref. Obert
Constant level is maintained in bowl -as float moves down, valve stem moves down, allowing more fuel into bowl, float moves up and closes valve
Valve StemFuel Inlet
Float
Metering Orifice
Throttle Plate
Air/Fuel Mixture To Engine
Choke Plate
Fuel Nozzle
Inlet Air
Bowl
Atomized Fuel
Venturi
Engine.ppt - 20 of 20
Product Dissection 04/07/98
Fuel Injection (electronic, multi-port)
50 psi typical
Monitored Engine Operating Conditions:
Manifold PressureEngine Speed
Air TemperatureCoolant Temperature
Acceleration
COMPUTERTRIGGER
INJECTOR DRIVE UNIT
Pressure Regulator FuelFilter
Fuel Pump
FUEL TANK
Injectors