Engine Dissection Project
Your team is 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 Dissection Project
Start engine. Disassemble engine. Review parts and functions – Ask questions! Reassemble engine. Re-start engine. Write individual report on how engine works.
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
Reciprocating to rotary motion
The pistons & crankshaftImage from:
http://www.eng.iastate.edu/explorer/topics/car/engine.htm
Piston, crankshaft,
& fly wheel
Image from:
www.web-masters.com/ gms/crank_p.html
PistonImage from:
www.rbracing-rsr.com/ 113orca.htm
darryl.hudson.home.mindspring.com/
ww.eng.iastate.edu/explorer/topics/car/engine.htm
Several common types of car engine arrangementImage from :
Automotive mechanics, 8th ed. By William H. Crouse
4 cylinder in-lineFlat-4 engine
Flat-6 engine6 cylinder in-line
V-6
V-8
4 cylinder 6 cylinder 8 cylinder
Power strokes in 2 crankshaft rotations
Why you need flywheelImage from :
Automotive mechanics, 8th ed. By William H. Crouse
time
Output torque
time
Output torque
Output torque
time
piston
valve
rocker
valve lifter
camshaft
cam
crankshaft
push rod
Valve Mechanisms:
How you get the
right timingImage from :
Automotive mechanics, 8th ed. By William H. Crouse
Timing marks
Fuel
Higher Pressure Outside Engine
VenturiChoke Throttle
Venturi-type Carburetor
The carburetor of our engine
How do engines work?
How does the engine complete these Primary Functions?
Get started? Suck in fuel? Suck in air? Mix air and fuel? Compress the mixture? Ignite the mixture (at the right time)? Make the combusting gases do work? Make the work available to somebody? Exhaust the gases? Shut off?
Think about the parts and processes involved for each.Hint
How do engines work?
How does the engine complete these Secondary Functions?
Stay lubricated? Operate the valves at the right time? Smooth out the power pulses? Store the fuel? Keep cool? Make it easy to start?
Think about the parts and processes involved for each.Hint
Some variations:
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
More variations:OHC( overhead camshaft):
DOHC, SOHC……Image from :
Automotive mechanics, 8th ed. By William H. Crouse
Crankshaft
Connecting rod
Piston
Camshaft
Valve lifter
RockerValve spring
Valve
2 Stroke Process (for comparison)
Compression(ports closed)Air Taken Into
Crankcase
Combustion(ports closed)
Exhaust(intake port closed)
Air compressed in crankcase
Scavengingand Intake
(ports open)
This presentation created by former ENGR 100 students Sam Henry, Thomas Munsey, Grayson Deitering, Daniel Munro
Wankel Rotary Engine•Smoother
•Engine is continuously moving in one direction rather than changing direction like in piston engines.
•Slower•Main moving parts move slower which increase the reliability of the engine.
•Fewer Moving Parts•The rotary engine consists of three main moving parts while a piston engine contains at least 40 moving parts.
•Challenges•Passing the US Emissions tests.•Manufacturing costs are higher.•Consumes more fuel.