4. FUEL INJECTION PUMP
A fuel injection pump is used to supply precisely metered
quantity of diesel under high pressure to the injectors at the
correct time.
94
11. • Delivery valve is a non return valve,
kept in position by a spring.
When the Pr. In the barrel exceeds a
predetermined value and valve opens
against the compression of the spring
and the pressure of the fuel above.
Fuel pump is connected to the fuel
injector through a passage
11
12. Working
Whentheplungerisat bottomthefuelinlet & overflow
portsareuncoveredandfilteredfuelisforcedinto thebarrel
Bothportsarecoveredwhentheplungermovesupwards
Fuel will get compressedwhentheplungermovesfurther
forward
Thehighpressureliftsthedeliveryvalveandfuel flowsout
thruthedeliveryvalve
With furtherriseof theplungertheoverflowport is
uncoveredbytheplungerandpressuredrops
12
17. FUEL INJECTOR
A fuel injector is used to inject the fuel in the cylinder
in atomised form and in proper quantity. Fuel
injectors are available in several designs. Main
components of fuel injectors are : NOZZLE
VALVE
BODY
SPRING
The nozzle is its main part which is attached to the
nozzle holder
. Entry of fuel in the injector is from the
fuel injection pump.
17
26. Ignition Systems
Ignition process in Petrol Engines requires an electric spark
producedat thesparkplug.
produced by the
This spark is generated by an electric discharge
ignitionsystem.
Ignitionsystemsinpetrol enginesareclassified as:
1.Batteryignitionsystem.
2.Magnetoignitionsystem
• The difference between the two systems is in the source of
primaryvoltage.
26
27. Ignition systems
Basicrequirementsof anignition systems
A sourceof electrical energy
A device for boosting thelowvoltage to produce highvoltage
A device fortiming anddistributingthehighvoltage to each
sparkplug
27
29. Battery ignition system
It isalsocalledcoil ignitionsystem.
The source of energy to the primary windings isa6V or
12V battery
.
As the number of windings in the secondary is 50 to 100
times more thanthat of the primary , the output voltage
inducedwill beof theorder of 10000vto 20000V
.
119
31. Magneto ignition system
The source of energy is either rotating magnets with fixed
coils or rotating coils withfixedmagnets.
The rapid collapse and reversal of magnetic field induces a
veryhighvoltagein thesecondarywinding.
It isgenerally employedinracingcars, motorcyclesetc.
31
33. The Spark Plug
Centre electrode receives coil voltage.
Insulator prevents high voltages
from shorting to ground.
T
erminal
Gap
Insulator
Gasket
Thread
Metal
shell
Hex
Centre
electrode
Side
electrode
Spark plug is located in the cylinder head,
it ignites the air and fuel mixture.
Has centre and side electrodes,
with an air gap between them.
High voltage jumps the
air gap, creating a spark.
Side electrode is grounded.
Next >
123
40. Dry Sump Lubrication System
Inawet sump, theoil pumpsucksoil fromthebottomof the
oil panthroughatube, andthenpumpsit to therestof the
engine.
Inadry sump, extraoil isstoredin atankoutsidethe
engineratherthanintheoil pan. Thereareat leasttwo oil
pumpsin adrysump-- onepullsoil fromthesumpand
sendsit to thetank, andtheothertakesoil fromthetankand
sendsit to lubricate theengine. Theminimumamount of oil
possibleremainsintheengine.
130
41. Dry sump lubrication
• Thesupplyof oil isfromanexternaltank.
• An oil pumpisemployedto circulate the oil underpressure
,fromthetankto variousbearingsof theengine.
131
42. Functions of a Lubricant
Lubricant reducesfrictionbetweenmovingpart.
It reduceswearandtear of themovingparts.
It minimizespowerlossdueto friction.
It providescooling effect.Whilelubricating it alsocarries
someheat fromthemoving partsanddeliversit to the
surroundingsthroughthebottomof theengine(crankcase).
It helpsreducenoisecreatedbythemovingparts.
42
44. Purpose of cooling
To regulate the engines internal temperature
To remove excess heat from the engine
To prevent heat to the passenger compartment
To Control temperature of hot combustion,4000 degree
temps. could seriously damage engine parts.
Cool Trans fluid & Oil
44
45. Cooling Systems
Intense heat is generated during the combustion of fuels
insidetheenginecylinder
.
30% of heat generated is converted into mechanical
work & 40% is carried away by exhaust gases to the
atmosphere.
The remaining part of heat (30%) will be absorbed by
the engine parts which leads to overheating of these
parts.
In order to avoid the problem of overheating it is
essentialto provide somekindcoolingsystems.
45
46. The two important characteristics of cooling systemsfor
theefficient working are:
(i)It should not remove more than 30% of heat
generated.(larger amount of heat removal reduces the
thermal efficiency)
(ii)The rate of cooling should not be constant.(the rate
of cooling should increase with increase in heat
generated)
46
52. Advantages of Air-cooled Engines:
Air-cooled engines are smaller and lighter because they don’
t
needtohouseanyof thosepartsliketheWater cooledengines
In some climates, water has the tendency to freeze and this is a
problemfor water-cooledengines.
Air-cooledengineswarmupquicklyandareeasytomaintain.
Disadvantages of Air-cooled engines:
Thecooling tendstobeunevenandleadstocylinder distortion.
It is almost impossible to manage withair-cooling if the number
of cylindersincreasesbeyondtwo.
Thefinsvibrate sometimesleadingto alot of noise.
52
53. Water cooling system.
It isalsocalledthermosyphonsystemof cooling.
Water iscirculatedthroughwater jacketsaroundeachof the
combustionchambers.
Thecirculating water iscooledbytheairdrawnthrough
radiator byafan
53
54. Liquid cooling (water cooling)
Coolingmedium–
water
Watercirculatedthroughthepassages
aroundthemaincomponents
Passages–
water jackets
Watercirculation- pumpor bygravity
force
54
55. Water after passingthroughthejacketsflowsto aradiator
.
Radiator coolshotwater withthehelpof movingairaroundthe
radiator tubes
Fansareprovidedto increasetheheat transferrate
Thissystemalsousesathermostat to control theflowof the
coolant
Antifreezeaddedto avoidfreezingof coolant- ethyleneglycol
55
57. Water Jackets
Surrounds the cylinders
with water passage.
Absorbs heat from the
cylinder wall.
Pump move water to
radiator where heat is
exchanged to the air.
57
58. 48
Radiators
Aradiator is a heat
exchanger.
Tube and fin style the
most popular.
Made of copper and
brass or aluminum and
plastic.
1
59. Itsjob isto blocktheflowof coolant to theradiator until the
enginehaswarmedup.
Whentheengineiscold, nocoolantflowsthroughthe
engine. Oncetheenginereachesits operating temperature
(generallyabout 200degreesF
, 95degreesC), the
thermostat opens.
Bylettingtheenginewarmupasquicklyaspossible, the
thermostat reducesenginewear
, depositsandemissions.
149
66. Working
HP fuel pumpmaintainsfuel in thecommonrail at apressure
of about 200MPa.
Commonrail branchesoff to ECU controlledinjectorvalves
Valvecontainsprecisionmachinednozzlesandaplunger
drivenbysolenoidvalves
ECU controlsthetiming andquantity of fuel injected
dependingontheloadconditions
66
70. Gasoline direct injection
Petrol Direct Injection or Direct Petrol
Injection or Spark Ignited Direct Injection
(SIDI) or Fuel Stratified Injection (FSI)
160
74. MULTI POINT FUEL INJECTION
Petrol vehiclesusedcarburettor for supplyingtheairfuel mixturein
correct ratioto cylindersinall rpmranges.
Carburettorachievesthisbybreakingupfuel into minuteparticles and
mixingit withair
.
Butthisprocessmaynotalwaysbeperfect andmight reduce the
performanceof theengine.
Therefore, multi pointfuel injection system(MPFI)isused,whichcan
assureproperairfuel ratio to anSI engine.
74
75. MPFI
MPFI standsfor multi-pointfuel injection
It allowsmoreefficientcombustionof fuel,thereby
producingmorepowerwithlessemissions
It issimilarto CRDI indieselengines
All modernpetrol enginesuseMPFI systems
75
77. MPFI System
MPFI doesthesamefunction asthecarburettor
It hasinjectorswhichspraycorrect quantity of fuel for each
cylinder
Thefuel andair aremixedintheintakemanifold before
admissionto thecylinder
77
78. Components of MPFI
Electronic Control Unit (ECU)- sometimescalledEngine
Control Module(ECM)
High PressurePumpModule-pump, filter
, pressure
regulator
, commonrail, sensor
Injectorfor eachcylinder
, alsocontrolledbyECU
78
80. The function of ECU is to receive inputs from
various sensors, compare them with pre-loaded
engine and throttle parameters and send control
signals to the actuators.
Sensors: Sense different parameters
(T
emperature, Pressure, Engine Speed etc.) of the
engine and send signal to ECU.
Actuators: Receive control signal from ECU and
actuates pump and injectors
ECU
80
82. Thusit makestheenginecleaner
, moreresponsive, ensures
completecombustion,anduseslessfuel asit knowswhat
amountof petrol shouldgo in.
Modern cars
’
ECUs have memory, which will remember
your drivingstyle andwill behaveinawaysothat youget the
desiredpower output fromenginebasedonyour driving
style.
For example, if youhaveahabit of speedypick-up, car’
s
computerwill remember that andwill giveyou morepower
at lowenginespeedsbyputtingextrapetrol, sothat yougeta
goodpick-up. It will typicallyjudgethisbytheamountof
pressureyouputonaccelerator
.
82
85. A multi-point injection system, also called port injection, hasan
injectorintheport (air-fuel passage)goingto eachcylinder
.
Gasoline issprayed into eachintake port andtowardeachintake
valve. Thereby
, the term multipoint (more than one location)
fuel injection isused.
85
87. ADVANTAGES OF MPFI SYSTEMS OVER
SPFI SYSTEM
17
MPFI SPFI
Better power Low power
Better refinement of engines Lesser refinement of engines
Better control over the process Lesser control over the process
Longer life due to lesser load per
injector
Lesser life due to higher load
Cleaning not required frequently Frequent cleaning is required
No delay in response Delay in response
No difference in delivery to each
cylinder
7
Difference in delivery to each
cylinder
