Transcript Engine Dissection

ME240/107S: Product Dissection
ME240/107S: Engine Dissection
You are dissecting a 3.5 HP
single cylinder, 4 cycle
engine, made by Briggs &
Stratton in Milwaukee, WI
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)
ME240/107S: Product Dissection
Lecture 3

Material Considerations

Why Internal Combustion?

Engine Labeling Diagram
ME240/107S: Product Dissection
Session 2: Engine Block and Drivetrain

What materials are used in the camshaft?
How are the cams fastened to the shaft?

What material is used for the crankshaft?

What manufacturing processes were used
for the crankshaft, camshaft, connecting
rod, wrist pin, and piston?

What type of lubrication system does your
engine have and how does it work? Which
components receive lubrication?
ME240/107S: Product Dissection
Crankshaft

Originally steel forged;
however, large stiff
crankshafts with
relatively low stresses
allowed cast iron to be
substituted as a
means to reduce cost

How is crankshaft
supported?
ME240/107S: Product Dissection
Piston Assembly

Piston: aluminum, cast steel
or cast iron

Wrist pin: machined steel

Connecting rod: forged-steel
or cast iron
ME240/107S: Product Dissection
Cylinder Head and Crankcase

Crankcase and cylinder
block are usually cast
iron; however, some
have been assembled
from welded steel plate

Crankcase and cylinder
are usually integral for
greater rigidity

How is cylinder
head made?
Cylinder block
Crank case
ME240/107S: Product Dissection
Cylinders

How are cylinders fabricated?
 Gray
cast iron with cylinder bores machined to
meet tolerance

Why must a new engine be “broken in”?
 Cast
iron forms a hard glazed surface when
subject to sliding friction
 When first assembled, slow speeds and light
loads should be used to facilitate forming this
protective coating to give long engine life
ME240/107S: Product Dissection
Camshaft and Cams

Camshaft and cams are
usually made from steel

In your Briggs & Stratton
engine, how is camshaft
made? How are cams
fastened?
What does the little
metal flapper do?
ME240/107S: Product Dissection
Valves

Intake valve: a
chromium-nickel
alloy

Exhaust valve: a
silicon-chrome alloy
since it operates at
higher temperatures
(about 1200oF)
ME240/107S: Product Dissection
Engine Temperature Profiles

What two
purposes
does engine
lubrication
serve?
 minimize
friction
 dissipate
heat
ME240/107S: Product Dissection
How does your engine lubrication
system work?

An oil pan seals
the engine block,
providing a
reservoir for
lubricating oil for
most drivetrain
components
Dip stick
Oil gallery
(for piston)
Oil gallery
Oil pan

How is oil pan
fabricated?
ME240/107S: Product Dissection
Automotive Fuel Needs
x1.1
x2.2
x2.5
After combustion and friction losses are considered, only
about 1/6 of energy available in gasoline is actually used
ME240/107S: Product Dissection
Minimizing
Losses
ME240/107S: Product Dissection
Streamlining to Reduce Air Drag
ME240/107S: Product Dissection
Why Internal Combustion?

IC engines were thought to have a bleak
future when first invented
“You can’t get people to sit over an explosion”
“The automobile industry will surely
burgeon…but this motor will not be a factor.”
- Col. Albert A. Pope, largest
automobile manufacturer at the
turn of the century
ME240/107S: Product Dissection
Why Internal Combustion?

Each group will be assigned either a steam,
electric, or internal combustion engine.

Within your group, discuss the pros/cons of
your particular type of engine based on
what you know and read in “Why IC?” article

At the end of your discussion, be prepared
to share your results with the class
ME240/107S: Product Dissection
History of IC Engines
1860 Lenoir’s
engine (a converted
steam engine)
combusted natural
gas in a double
acting piston, using
electric ignition
ME240/107S: Product Dissection
Stanley Steamer
ME240/107S: Product Dissection
History - continued

1876 Nikolaus Otto patented the 4 cycle engine;
it used gaseous fuel

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. It used liquid fuel and Venturi type
carburetor, engine was named “Mercedes” after
the daughter of his major distributor

1893 Rudolf Diesel built successful IC engine
which was 26% efficient (double the efficiency of
any other engine of its time)
ME240/107S: Product Dissection
Complementary Technologies for
IC Engine-powered Automobiles

Pneumatic tires (1888, Dunlop)

Cheap liquid fuels (Oil industry born in PA 1859)

Venturi effect carburetor (1892, Willi Maybach)

Variable mechanical transmission (primitive type
by Levassor, 1891)

Electric starter (1912 by Kettering of Cadillac)
 The real end to electric cars? http://usat.ly/wRmS5K
ME240/107S: Product Dissection
Parts of an
IC Engine
Name as many
parts as you can
Your name:_________________
CROSS SECTION OF OVERHEAD VALVE FOUR CYCLE SI ENGINE