auto material engine
DESCRIPTION
Learn about materials used in its Manufacturing and its characteristics and its functons.TRANSCRIPT
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AUTOMOTIVE MATERIALS
Prepared By: Mr. Hardik Shah
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Syllabus
1. Engines
2. The cylinder
3. The piston & piston ring
4. The camshaft & crankshaft
5. The connecting rod
6. The catalyst
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Contents
The reciprocating engine
Advantages and disadvantages of
reciprocating engines
Engine components and typical materials
Recent trends in engine technology
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The reciprocating engine
The reciprocating engine is an engine in
which one or more pistons move up and
down in cylinders which gives power to
crankshaft to rotate. The engine is the heart of a car although it
is normally hidden under the bonnet.
Another type is rotary engine.
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Basics of Reciprocating Engines
The cylinder which is closed atone end is filled with amixture of fuel and air.
As the crankshaft turns it
pushes piston. The piston is forced up and
compresses the mixture in thetop of the cylinder.
The mixture is set alight and,as it burns, it creates a gas
pressure on the piston, forcingit down the cylinder.
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Constructional details of Reciprocating
Engines
A cross-section of an air-cooled engine with principal parts isshown in next page.
A. Parts common to both Petrol and Diesel engine:
1. Cylinder, 2. Cylinder head, 3. Piston,4. Piston rings, 5. Gudgeon pin, 6. Connecting rod,
7. Crankshaft, 8. Crank, 9. Engine bearing,
10. Crank case. 11. Flywheel, 12. Governor,
13. Valves and valve operating mechanism.
B. Parts for Petrol engines only:
1. Spark plug, 2. Carburetor, 3. Fuel pump.
C. Parts for Diesel engine only:
1. Fuel pump, 2. Injector.
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Four Stroke Engine
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Working of Four Stroke Engines
1. Intake stroke: the intake stroke draws air and fuel intothe combustion chamber. The piston descends in the
cylinder bore to evacuate the combustion chamber.
When the inlet valve opens, atmospheric pressure forces
the air-fuel charge into the evacuated chamber. As a
result, the combustible mixture of fuel and air fills the
chamber.
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Working of Four Stroke Engines
2. Compression stroke: at the end of the intake stroke, bothinlet and exhaust valves are closed. The inertial action of
the crankshaft in turn lifts the piston which compresses
the mixture. The ratio of the combustion chamber
volume before and after compression is called thecompression ratio. Typically the value is approximately
9:1 in spark ignition engines and 15:1 in diesel engines.
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Working of Four Stroke Engines
3. Power stroke: when the piston ascends and reaches topdead center, an electric current ignites the spark plug and
as the mixed gas burns, it expands and builds pressure in
the combustion chamber. The resulting pressure pushes
the piston down with several tons of force.
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Working of Four Stroke Engines
4. Exhaust stroke: during the exhaust stroke, the inlet valveremains closed whilst the exhaust valve opens. The
moving piston pushes the burned fumes through the now
open exhaust port and another intake stroke starts again.
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Salient Features About Engines
During one cycle, the piston makes two round trips andthe crankshaft revolves twice.
The inlet and exhaust valves open and close only once.
The ignition plug also sparks only once.
A petrol engine, whether four- or two-stroke, is called aspark ignition (SI) engine because it fires with an
ignition plug.
The four-stroke-cycle engine contains the lubricating oil
in the crankcase. The oil lubricates the crankshaft bearings and cools the
hot piston
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The two-stroke engine is similar to that of the
four-stroke-cycle engine in its reciprocatingmechanism.
It uses the piston-crankshaft mechanism, butrequires only one revolution of the crankshaftfor a complete power-producing cycle.
The two-stroke engine does not use inlet andexhaust valves.
The gas exchange is implemented byscavenging and exhaust porthole openings inthe bore wall. The upward and downward
motion of the piston simultaneously opens andcloses these portholes. The air-fuel mixturethen goes in or out of the combustion chamberthrough the portholes. Combustion takes placeat every rotation of the crankshaft.
Two-stroke Engines
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The gas exchange is implemented byscavenging and exhaust porthole openings inthe bore wall.
The upward and downward motion of thepiston simultaneously opens and closes theseportholes.
The air-fuel mixture then goes in or out of thecombustion chamber through the portholes.
After spark ignition inside chamber,Combustion takes place at every rotation ofthe crankshaft.
Working of Two-stroke Engines
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In the two-stroke engine, the space in the
crankcase works as a pre-compressionchamber for each successive fuel charge.
The fuel and lubricating oil are premixed
and introduced into the crankcase, so that
the crankcase cannot be used for storingthe lubricating oil.
When combustion occurs in the cylinder,
the combustion pressure compresses the
new gas in the crankcase for the nextcombustion.
The burnt gas then exhausts while drawing
in new gas. The lubricating oil mixed into
the air-fuel mixture also burns
Features of Two-stroke Engines
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Diesel Engine
The only difference between
diesel engine and a four-stroke
gasoline engine is:
No sparkplug on Diesel engine.Has a higher compression ratio.
(14:1 to 25:1)
Better fuel mileage.
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Diesel Engine
Intake Stroke:
Piston moves from TDC
to BDC
creating vacuum in the
cylinder Intake valve
opens allowing only
airto enter the cylinder
andexhaust valve remains
closed
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Diesel Engine
Compression Stroke
Both valves stay closed
Piston moves from BDC to TDC,
compressing air to 22:1
Compressing the air to this extent
increases the temperature inside the
cylinder to above 1000 degree F.
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Diesel Engine
Power Stroke
Both valves stay closed
When the piston is at the end of
compression stroke(TDC) the injectorsprays a mist of diesel fuel into the
cylinder.
When hot air mixes with diesel fuel
an explosion takes place in the cylinder.
Expanding gases push the piston
from TDC to BDC
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Diesel Engine
Exhaust Stroke
Piston moves from BDC to
TDC
Exhaust valve opens and the
exhaust gases escape
Intake valve remains closed
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Diesel Engine
Four Strokes of Diesel Engine
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Thepiston losesspeed at the dead-centerpoints where the
travelling direction reverses, which gives enough time forcombustion and intake as well as for exhaust.
The piston ring faces the cylinder bore wall, separated by
an oilfilm. The resulting lubrication generates low friction
and high durability. By sealingthe gapbetween the piston and the cylinder,
high compression ratio, high heat efficiency and low fuel
consumption can be achieved.
Advantages of Reciprocating Engine
It is difficult to reuse the exhaustheat.
The unbalanced inertial force may results inpiston slap
that can cause noise and vibration.
Disadvantages of Reciprocating Engine
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Engine Components
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Parts Of An Engine.
PISTON
SPARK PLUG
CAM SHAFT
VALVE
ROCKER ARM
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Components and its work
Cylinder
A cylinder is the central working part
of a reciprocating engine or pump, the
space in which a piston travels
Gray cast iron, compact graphitecast iron, cast Al alloy
Piston
its purpose is to transfer force fromexpanding gas in the cylinder to
the crankshaft via a piston rod and/or
connecting rod
Al-Si-Cu-Mg alloy
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Components and its work
Piston rings
Piston rings provide a sliding sealbetween the outer edge of the piston
and the inner edge of the cylinder.
The rings serve two purposes:
They prevent the fuel/air mixture andexhaust in the combustion chamber
from leaking into the sump during
compression and combustion.
They keep oil in the sump fromleaking into the combustion area,
where it would be burned and lost.
Gray cast iron, spheroidized graphite
cast iron, alloy cast iron, spring steel
and stainless steel
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Components and its work
Connecting rod
The connecting rod connects the piston to the
crankshaft. It can rotate at both ends so that its anglecan change as the piston moves and the crankshaft
rotates.
Carbon steel, iron base sintered metal, micro-alloyed
steel, spheroidized graphite cast iron
CrankshaftThe crankshaft turns the piston's up and down motion
into circular motion just like a crank on a jack-in-the-
box does
Carbon steel, micro-alloyed steel, Cr-Mo steel and
nodular, cast iron
Sump
The sump surrounds the crankshaft. It contains some
amount of oil, which collects in the bottom of the sump
(the oil pan).
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Components and its work
Camshaft
Its an internal component of valve train whichcontrols the valve operation timing with pushrod or
rocker arms or self controlling lobes.
Chilled cast iron, Cr-Mo steel, iron base sintered
metal
Valve and Valve springThe valve which allows mixture into the cylinder is
the inlet valve; the one through which the spent
gases escape is the exhaust valve. They are designed
to open and close at precise moments, to allowthe engine to run efficiently at all speeds.
Valve: Heat-resistive steel, Ti alloy, SiC ceramics.
Valve spring:Spring steel, music wire
Valve Seat: Iron base sintered metal, cast iron
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Components and its workExhaust Manifold
The exhaust manifold is the first part of your vehicles exhaust
system.
It is connected to your vehicles engine and collects your
engines emissions.
The exhaust manifold receives the air/fuel mixture from the
multiple cylinders in your vehicles engine, it completely burnsany unused or incomplete burnt gases using its very high
temperature.
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Components and its workExhaust Manifold
The manifold also houses the first
oxygen sensor in your exhaust
system to inspect the amount of
oxygen entering the system.
Once the amount of gas in one
place completely burnt, the manifoldsends the emissions into the rest of
the exhaust system.
High-Si cast iron, niresist cast iron,cast stainless steel,stainless steel
tube and sheet
C d i k
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Components and its work
Engine Bearings
Bearing is a device supporting a mechanical
element and providing its movement relatively to
another element with a minimum power loss.
Main crankshaft bearings
It support the crankshaft and help it rotate under inertia forces
generated by the parts of the shaft and oscillating forces
transmitted by the connecting rods. Main bearings are
mounted in the crankcase
Connecting rod bearings
provide rotating motion of the crank pin within the
connecting rod, which transmits cycling loads applied to thepiston. Connecting rod
bearings are mounted in the Big end of the connecting rod.
Camshaft bearings
It support camshaft and provide its rotation.
Al-Si-Sn and Cu-Pb alloys
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Recent trends in engine technology1. The multi-valve engine was previously limited to sports
cars and motorcycles. To obtain higher output power, thenumber of valves used in car engines has increased.
2. The multi-cylinder engine has become more widespread.
It has a smoother rotation to decrease noise and
vibration.
3. Three-way catalyst (Pt-Pd-Rh alloy) technology, usingO2 and knock sensors, has decreased the three
components CO, HC, and NOx in the exhaust gas, to
decrease environmental pollution.
4. The variable valve system has decreased fuel
consumption.
5. Decreased inertial weight and electronic control have
given improved engine performance.
6. Hybrid systems including an electric motor have reduced
fuel consumption.
Part name Material
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Part name Material
Cylinder block Gray cast iron, compact graphite cast iron, cast Al alloy
Piston Al-Si-Cu-Mg alloy
Piston ring
Gray cast iron, spheroidized graphite cast iron, alloy cast iron, spring steel and
stainless steel
Camshaft Chilled cast iron, Cr-Mo steel, iron base sintered metal
Valve Heat-resistive steel, Ti alloy, SiC ceramics
Valve seat Iron base sintered metal, cast iron
Valve spring Spring steel, music wire
Piston pin Nodular cast iron, Si-Cr steel, stainless steel
Connecting rodCarbon steel, iron base sintered metal, micro-alloyed steel,spheroidized graphite
cast iron
Crankshaft Carbon steel, micro-alloyed steel, Cr-Mo steel and nodular,cast iron
Turbo charger Niresist cast iron, cast stainless steel, superalloy
Exhaust manifoldHigh-Si cast iron, niresist cast iron, cast stainless steel,stainless steel tube and
sheet
Plain bearing Al-Si-Sn and Cu-Pb alloys
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The science and
technology of materials inautomotive engines
by Hiroshi Yamagata
Automotive Engineering
Lightweight, Functional,and Novel Materials
by Brian Cantor.
Advance composite
materials for automotiveapplications
by Ahmed Elmarakbi
Reference Books