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8/10/2019 2 Engine Components and Operation
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Engine Components and
Operation
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Objectives
Explain the basic function of an internalcombustion engine.
Describe the five events required for internalcombustion engine operation.
Describe selected individuals and events in thehistory of engine development.
Identify and describe the construction andfunction(s) of primary engine components.
Explain principles of 2- and 4-stroke cycle engineoperation, both S.I. And C.I.
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Internal Combustion Engine Function - Converts
potential chemical energy
in fuel into heat energy
then to mechanical energyto perform useful work.
Chemical
Heat
Mechanical
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Requirements for
I.C. Engine Operation
All Internal combustion enginesmust carry out five events:
Air-fuel mixture must be
brought into the combustionchamber.
Mixture must be compressed.
Mixture must be ignited.
Burning mixture must expandinto increasing combustionchamber volume.
Exhaust gasses must beremoved.
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Historical Development
of the I.C. Engine
1862 -- Rochasdescribed the basic principles
essential for efficient engine operation.
1878Ottobuilt the first successful 4-stroke cycle
engine. 1891Daybuilt an improved 2-stroke cycle engine.
1892Dieselpatented the compression-ignition
(diesel) engine. To presentemphasis on improved engine
efficiency, through refinement.
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Engine Components
and Functions
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Name that Engine Part
1
2
3
4
5
6
7
8
910
11
12
13
14
15
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Name that Engine Part
Valve cover
Valve spring
Valve
Connecting rod
Engine block
Rocker arm
Push rod
Valve tappet
Camshaft
Connecting rod
Main journalConnecting rod cap
Piston pin
Oil pan
Piston
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Engine Parts ID Scoring
14 - 15 correctMaster Gearhead
12-13Gearhead
10 -11Mechanic 8 - 9 -- Apprentice Mechanic
67Wrench Turner
45Wrench Loser
2 -- 3Jiffy Lube Customer
01 Cant Find Jiffy Lube
Looking for Lube in all the Wrong places????
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Cylinder Block
Backbone of the engine.
Supports / aligns most
other components.
Part of basic tractor
frame.Contains:
Cylinders
Coolant passagesOil passages
Bearings
One-piece, gray cast iron
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Cylinders
Cylindrical holes inwhich the pistonsreciprocate.
May be:
Enblock
Liners
Wet liners
Dry liners
Cylinder borediameter of cylinder
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Checking Cylinder Condition
During engine
overhaul, cylinder is
checked for: Excessive wear
(oversize)
Out-of Round
Taper
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Bearings and JournalsBearing
Journal
BearingStationary (non-rotating) surfaces providingsupport to moving(rotating) component.
Main bearings
Rod bearings
Cam bearings
JournalSurface ofmoving componentsupported by a bearing.
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JOURNAL BEARING
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Cylinder Head
Seals the top-end of the
combustion chamber.
Contains the valves and
the intake and exhaustports.
Head bolts and head
gasket ensure air-tight seal
of the combustion chamber.
Contains oil and coolant
passages.
One-piece castings of iron
alloy.
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Valve Train
Controls flow into and out ofthe combustion chamber. Time and Duration
Tractor engines use Overhead
Valve (OHV) configuration. Components
Camshaft
Valve tappets
Push rods
Rocker arm
Valves
Valve springs
Valve rotators
Valve seats
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Camshaft
Lift
Base circle
Nose
Cam Profile
Open the intake and exhaust valves at correct timeand for correct duration.
Driven by gear (or chain) from the crankshaft.
2:1 crankshaft to camshaft gear ratio.
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Valves
Each cylinder will have:
Intake valve
Exhaust valve
Valve nomenclature
Head
Margin
Face
Tulip
Stem
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Piston and Rings
Piston
Forms the moveablebottom of the
combustion chamber. Iron alloy or aluminum
Rings
Compression
Oil-control Cast iron
Piston pin
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Know Your Piston!
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Connecting rod
Connects the piston to
the crankshaft
Converts reciprocatingpiston motion to rotary
motion at the
crankshaft.
Nomenclature
Drop-forged steel
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Crankshaft
Works with connecting rod to change reciprocating torotary motion.
Transmits mechanical energy from the engine.
Made of heat-treated steel alloys.
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Cylinder Bore
Bore is the diameter
of the cylinder
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Stroke
TDC
BDC
Stroke
Linear distance piston
travels from Top Dead
Center (TDC) to BottomDead Center (BDC).
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Piston and Engine
Displacement
Pd = (B2 x pi x s) / 4
Ed = [(B2x pi x s) / 4]
x n
BDC
TDC Volume "displaced"as Piston moves fromBDC to TDC
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Compression Ratio
BDCTDC
Ratio of Total Volume in cylinder at BDC to TDC.
C.R. = (Pd + ClV) / ClV
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Compression Ratio and
Gasoline Octane RatingCR Octane Rating
BDC TDC
5:1 73
6:1 81
7:1 87
8:1 91
10:1 98
11:1 100
12:1 102
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Compression Ratio and
Theoretical Otto Cycle EfficiencyBDC TDC
http://localhost/var/www/apps/conversion/Ottoefficiency.xlshttp://localhost/var/www/apps/conversion/Ottoefficiency.xlshttp://localhost/var/www/apps/conversion/Ottoefficiency.xls8/10/2019 2 Engine Components and Operation
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4-Stroke Cycle Engine Operation
4-stroke cycle enginesrequire four strokes ofthe piston to complete
the five eventsnecessary for engineoperation.
1 piston stroke =
crankshaft revolution. 4 piston strokes = 2
crankshaft revolutions.
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4-Stroke Cycle Engine Operation
Intake Stroke
Intake valve open.
Piston moves down(TDC to BDC) incylinder.
Low pressure iscreated in cylinder.
Air is brought into thecombustion chamberdue to pressuredifferences.
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4-Stroke Cycle Engine Operation
Compression Stroke
Both valves closed.
Piston moves from BDC
to TDC
Air in combustion
chamber is compressed,
raising its temperature.
Near TDC of
Compression stroke,diesel fuel is injected into
the combustion chamber.
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4-Stroke Cycle Engine Operation
Power Stroke
Both valves are closed
Air-fuel mixture burnsrapidly
Expansion of the
burning air-fuel mix
applies force to the
head of the piston
Piston is driven down
in the cylinder.
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4-Stroke Cycle Engine Operation
Exhaust Stroke
Piston moves from
BDC to TDC.
Exhaust valve is open.
Burnt air-fuel mixture
is scavenged from
combustion chamber.
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4-Stroke Cycle C.I. Engine
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Comparison of 4-Stroke Cycle
for C.I. And S.I. EnginesStroke C.I. (Diesel) S.I. (Gasoline)
Intake Air only Air-fuel mix
Compression C.R. > 14:1
Temp > 729 oF
C.R. 6:112:1
Power No difference
Exhaust No difference
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Two-Stroke Cycle Engines
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Two-Stroke Cycle
Engine Operation
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Comparison of Two-Stroke
vs. Four-Stroke Cycle Engines
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