Transcript Main parts of spark ignition system

Four stroke engine
INTAKE STROKE:
During this stroke, the piston is moving downward
and the intake valve is open.
This produces a partial vacuum in the cylinder, and
the air-fuel mixture rushes into the cylinder
Compression Stroke
When the piston reaches bottom dead center (BDC)
, the intake valve closes. As the crankshaft
continues to rotate, it pushes up through the
connecting rod on the piston.
The piston is therefore pushed upward and
compresses the combustible mixture in the
cylinder
Power stroke
 As the piston reaches top dead center (TDC) .
 the compressed air-fuel mixture is ignited. In
burning, the mixture gets very hot and tries to expand
in all directions.
 The pressure rises. the force produced by the
expanded gases forces the piston down.
Exhaust stroke
 After the air-fuel mixture has burned, it must be
cleared from the cylinder.
 This is done by opening the exhaust valve just as the
power stroke is finished, and the piston starts back up
on the exhaust stroke
Firing order
 The firing order is the sequence of power delivery of
each cylinder in a multi-cylinder reciprocating engine.
 This lead to:
smooth running,
for long engine fatigue life and user comfort
heavily influences crankshaft design.
number of
cylinders
firing order
example

4
1-3-4-2
1-2-4-3
1-3-2-4
Most straight-4s, Ford Taunus V4 engine
Some English Ford engines, Ford Kent engine
Yamaha R1 crossplane
5
1-2-4-5-3
Straight-5, Volvo 850, Audi 100
6
1-5-3-6-2-4
1-6-5-4-3-2
1-2-3-4-5-6
1-4-2-5-3-6
Straight-6, Opel Omega A
GM 3800 engine
GM 60-Degree V6 engine
Mercedes-Benz M104 engine
8
1-8-4-3-6-5-7-2
1-8-7-2-6-5-4-3
1-3-7-2-6-5-4-8
1-5-4-8-7-2-6-3
1-6-2-5-8-3-7-4
1-8-7-3-6-5-4-2
1-5-4-2-6-3-7-8
1-5-6-3-4-2-7-8
1-5-3-7-4-8-2-6
1988 Chrysler Fifth Avenue, Chevrolet SmallBlock engine
GM LS engine
Porsche 928, Ford Modular engine, 5.0 HO
BMW S65
Straight-8
Nissan VK engine
Ford Windsor engine
Cadillac V8 engine 368, 425, 472, 500 only
PISTON
COMPONENT OF PISTON
 The piston head
is the top surface (closest to the cylinder head) of the piston
which is subjected to tremendous forces and heat during
normal engine operation.
A piston pin bore
is a through hole in the side of the piston perpendicular to
piston travel that receives the piston pin
 A piston pin
is a hollow shaft that connects the small end of the
connecting rod to the piston.
 The skirt of a piston
is the portion of the piston closest to the crankshaft that helps
align the piston as it moves in the cylinder bore. Some skirts have
profiles cut into them to reduce piston mass and to provide
clearance for the rotating crankshaft counterweights.
 A ring groove
is a recessed area located around the perimeter of the piston that is
used to retain a piston ring
. Piston rings are commonly made from cast iron. Cast iron retains
the integrity of its original shape under heat, load, and other
dynamic forces
 A compression ring
is the piston ring located in the ring groove closest to the piston
head. The compression ring seals the combustion chamber from
any leakage during the combustion process
 A wiper ring
is the piston ring with a tapered face located in the ring groove
between the compression ring and the oil ring. The wiper ring is
used to further seal the combustion chamber
 An oil ring
is the piston ring located in the ring groove closest to the
crankcase. The oil ring is used to wipe excess oil from the
cylinder wall during piston movement. Excess oil is returned
through ring openings to the oil reservoir in the engine block.
 There are many reasons for using aluminum alloys in
pistons for gasoline and diesel engines
 low weight,
 high thermal conductivity,
 very good recycling properties.
 Low expansion coefficients
 1-Foundry
 The foundry is the beginning of the piston. At the foundry the
die is prepared by heating it to operating temperature for
approximately one hour. This process allows the die to readily
accept the molten material when it is poured.
 The material
The material used is(7- 10%) silicon Content aluminum.
 The dies
The die used are 5 piece and three piece. These dies are made from
cast iron with
steel inserts for the gudgeon pin holes and the cores.
 The process
1. Heating the material to 700 degrees Celsius. (above the
melting point )
2. This is then poured into the die through the sprue. The
material is then allowed to cool
3. Placed into a bin of hot water.
4. Placed into a heat treatment plant overnight. This process
tempers the casting and ensures the piston will have improved
qualities.
 3-CNC Turning
 Turning on CNC machinery.
 This equipment is the most accurate and fastest available for
this application with
 very tight tolerances and extremely fast spindle speeds.

 the high fatigue resistance with optimized conditions in
respect to chemical composition, production and heat
treatment.
Before the stroke
 The intake valve is open before the piston reaches the (TDC)
by 25° To pull exhaust gases out from the cylinder
After the stroke
 The intake valve will remain opened till the crank rotate about
71 ° To make sure the the complete charge is entire into the
cylinder
:
Before the stroke
 The exhaust valve is open before the piston reach to BDC by 78°
To make complete scavenging of gases from the cylinder
After the stroke
 The exhaust valve will remain opened till the crank rotate about
45°
This happened because:
Using turbo charger belong to truck
in small vehicle
The turbo make the power is very
high
but the temperature also is very high
so the piston and the engine is
damaged
Take into consideration
1-The material of component
2-The temperature at the end of
power stroke
3- The pressure at the end of power
stroke
4- The emission of the engine
5- Fuel consumptions
 * The suction gas fed into the combustion chamber is
compressed by a constant ratio at all times.
 *Then the pressure in the combustion chamber or gas
temperature at the end of the compression stroke changes
depending on the pressure in the combustion chamber or
gas temperature at the time of start of compression
 DEVELOPMENT
1- variable compression ratio mechanism
2- variable valve timing mechanism able to control a
closing timing of a an intake valve
 And that leads to
 that an amount of intake air in accordance with the
required load is fed into a combustion chamber
 the temperature of the gas
 pressure in the combustion chamber
 the density of gas in the combustion
 at the end of the compression
stroke becomes substantially
constant under substantially
the same engine speed regardless of the engine load.
CRANK SHAFT
 The crankshaft
 sometimes casually abbreviated to crank, is the part of an
engine which translates reciprocating linear piston motion
into rotation.
 Main Journals:
The crankshaft's main journals are the highly polished surfaces
located at the center of the shaft. The rotation axis of the
crankshaft runs through the center point of the main journals.
 Rod Journals:
The rod journals are highly polished surfaces to which the
connecting rods attach. They circle around the crankshaft's axis
of rotation.
 Counterweights:
Counterweights balance the crankshaft.
 these are typically cast as part of the crankshaft but,
occasionally, are bolt-on pieces
 smoother running engine and allows higher RPMs to be
reached.
 Crank nose:(snout)
The crankshaft snout extends through the front end of the
engine block. The camshaft timing assembly is directly
connected to the snout, as are engine-driven accessories.
 Flange:
The crankshaft flange is the mounting structure for the
engine's flywheel.
 is simply a heavy wheel, usually composed of metal. from disk
to saucer, and is typically symmetric.
 flywheel used for
Energy store:
 Store energy from power stroke and use it
to make the other strokes
Stability
 It has big mass and make stability
for engine
Cam shaft used for
 operating the valves. The camshaft can be either be located
overhead or at the side of the engine
 It get its motion from crank shaft through system of gears
 The product of combustion chamber pressure
That level of force exerted onto a crankshaft rod journal
produces substantial bending and tensional moments and
the resulting tensile, compressive and shear stresses.
 Piston Acceleration
is another major source of forces imposed on a crankshaft.
The combined weight of the piston, ring package, wristpin,
retainers, the conrod small end and a small amount of oil
are being continuously accelerated from rest to very high
velocity and back to rest twice each crankshaft revolution.
 The steel alloys typically used in high strength crankshafts
have been
 Surface and core hardness
 Ultimate tensile strength,
 Yield strength, endurance limit (fatigue strength),
 impact resistance, corrosion resistance
 Forging and casting
 Crankshafts can be forged from a steel bar usually through
roll forging or cast in ductile steel. Today more and more
manufacturers tend to favor the use of forged crankshafts
due to their lighter weigh.
 Machining
 Crankshafts can also be machined out of a billet, often
using a bar of high quality vacuum remelted steel. Even
though the fiber flow
 Heating the part in an oven until the temperature throughout
the part (1550°F to 1650°F )
 the part is removed and rapidly cooled ("quenched”). (high-
strength, high-hardness- lacks sufficient ductility and impact
resistance)
 the part is placed in a ‘tempering’ oven and soaked for a
specific amount of time at a specific temperature (doubletempering)
 Nitriding is the process of diffusing elemental nitrogen into
the surface of a steel, producing iron nitrides (FeNx). The
result is a hard, high strength case along with residual surface
compressive.
 According to
No of stroke:
2-stroke engine
4-stroke engine
System of cooling
Water cooling
Air cooling
System of ignition
Spark ignition engine
Compression ignition engine
Fuel
Gasoline engine
Diesel engine
Alcohol engine
Natural gas
 Straight engine(inline)
 Usually found in four- and six-cylinder configurations, the
straight engine, or inline engine is an internal-combustion
engine with all cylinders aligned in one row, with no offset.
They have been used in automobiles
Flat Engine
 A flat engine is an internal combustion engine with multiple
pistons that all move in the horizontal plane. The most
popular and significant layout has cylinders arranged in two
banks on either side of a single crankshaft
V engine
 is a common configuration for an internal combustion
engine. The cylinders and pistons are aligned, in two separate
planes or 'banks', so that they appear to be in a "V" when
viewed along the axis of the crankshaft. The Vee configuration
generally reduces the overall engine length, height and weight
compared to an equivalent inline configuration.
V and VR
ENGINE
The W engine
 is an engine configuration in which the cylinder banks
resemble the letter W in the same way a V engine

Rotary Engine
 The rotary engine was an early type of internal-combustion
engine, usually designed with an odd number of cylinders per
row in a radial configuration, in which the crankshaft
remained stationary and the entire cylinder block rotated
around it.
U engine
 A U engine is a piston engine made up of two separate straight
engines (complete with separate crankshafts) joined by gears
or chains.
X engine
 An X engine is a piston engine comprising twinned V-block
engines horizontally-opposed to each other. Thus, the
cylinders are arranged in four banks, driving a common
crankshaft. Viewed head-on, this would appear as an X. X
engines were often coupled engines derived from existing
powerplants.
Wankel engine
 The Wankel engine is a type of internal combustion
engine which uses a rotary design to convert pressure
into a rotating motion instead of using reciprocating
pistons. Its four-stroke cycle takes place in a space
between the inside of an oval-like epitrochoid-shaped
housing and a rotor that is similar in shape to a
Reuleaux triangle but with sides that are somewhat
flatter. This design delivers smooth high-rpm power
from a compact size
 The engine was invented by German engineer Felix
Wankel