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

1. Intake 2. Compression

3. Power 4. Exhaust

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

Crankshaft

Image from :

toyotaperformance.com/crankshaft_kits.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

LubricationImage from :

Automotive mechanics, 8th ed. By William H. Crouse

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

More variations:VTEC( Variable valve timing and lift electronic control)

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.