8/9/2019 Diff Point
1/32
Submitted By
Vipin Kumar Gupta
VIth Sem
Diploma (Mech)
12114M02058
Submitted To
Dr. Narendra Wadekar
H.O.D.(Mechanical)
MULTI POINT FUEL
INJECTION
(MPFI)
Govt Polytechnic college katni
8/9/2019 Diff Point
2/32
INTRODUCTION
Air and fuel are supplied to an I.C.Engine whereexothermic reactions take place inside the combustion
chamber and the heat energy is converted into useful
work.
To produce energy inside the engine , air fuel mixture
is to be burnt in correct amount. For mixing the air and
fuel in correct range different devices are used.
The preparation of a homogeneous mixture of air-fuel
vapour mixture requires atomisation of liquid fuel
droplets and mixing the finely divided fuel particles
with air. The atomisation is accomplished by spraying
the liquid fuel through a nozzle into a stream of air
which is moving with large velocity.
8/9/2019 Diff Point
3/32
CARBURETOR
Petrol vehicles use device called carburetor for
supplying the air fuel mixture in correct ratio to
cylinders in all rpm ranges. due to construction of
the carburetor is relatively simple, it has been
used almost exclusively on gasoline engines inthe past.
These days in place of the carburetor, the MPFI
(multi point fuel injection) system is used,
assuring proper air fuel ratio to the engine byelectrically injecting fuel in accordance with
various driving conditions.
8/9/2019 Diff Point
4/32
FUEL ATOMISATION
During fuelling of a cylinder the fuel is pressurised
which causes the fuel to become a vapour,
allowing it to burn easily (compared to the fuel
being delivered to the cylinder in liquid form)
8/9/2019 Diff Point
5/32
FUEL INJECTION
The primary difference between carburetors andfuel injection is that fuel injection atomizes the fuel
by forcibly pumping it through a small nozzle under
high pressure, while a carburetor relies
on suction created by intake air accelerated through
a Venturi tube to draw the fuel into the airstream.
Modern fuel injection systems are designed
specifically for the type of fuel being used. Somesystems are designed for multiple grades of fuel
(using sensors to adapt the tuning for the fuel
currently used). Most fuel injection systems are for
gasoline or diesel applications.
8/9/2019 Diff Point
6/32
OBJECTIVES OF FUELINJECTION SYSTEM
The injection system of the compression ignitionengine should fulfill the following objectivesconsistently and precisely:
1. Meter the appropriate quantity of fuel, asdemanded by the speed of, and the load on, theengine at the given time.
2. Distribute the metered fuel equally amongcylinders in a multi-cylinder engine.
3. Inject the fuel at the correct time (with respectto crank angle) in the cycle.
4. Inject the fuel at the correct rate (per unit timeor crank angle degree).
5. Begin and end injection sharply withoutdribblin.
8/9/2019 Diff Point
7/32
There are two major divisions of Fuel Injection
systems:Solid Injection systems, which inject only the liquid fuel
through the injectors.
Air Injection systems, which inject air along with the
liquid fuel
8/9/2019 Diff Point
8/32
VARIOUS INJECTION SYSTEM
MPFIsystem
Port injection
ThrottleBody injection
L-MPFI System
D-MPFISystem
8/9/2019 Diff Point
9/32
THROTTLE BODY INJECTION SYSTEM
The throttle body injection (TBI) system uses one or twoinjector valves mounted in a throttle body assembly. The
injectors spray fuel into the top of the throttle body air horn.
The TBI fuel spray mixes with the air flowing through the
air horn. The mixture is then pulled into the engine by
intake manifold vacuum.
8/9/2019 Diff Point
10/32
Throttle Body Injection System
8/9/2019 Diff Point
11/32
L & D MPFI GASOLINE INJECTION
SYSTEM
I-mpfi systemstands forIntelligent-
Multi Point Fuel Injection System, and
D-mpfi systemstands forDirect-Multi Point
Fuel Injection System.
8/9/2019 Diff Point
12/32
D-MPFI GASOLINE INJECTION
SYSTEM
The D-MPFI system is the manifold fuel injection
system . In this type , the vacuum in the intake
manifold is first sensed .In addition the volume of
air is sensed by its density . As air enters into the
intake manifold ,the manifold pressure sensordetects the intake manifold vacuum and sends the
information to the ECU . The speed sensor also
sends the information about the rpm of the engine
to the ECU . The ECU in turn sends command tothe injector to regulate the amount of gasoline
supply for injection . When the injectors spray fuel
in the intake manifold the gasoline mixes with the
air and the mixture enters the cylinder.
8/9/2019 Diff Point
13/32
L & D MPFI GASOLINE INJECTION
SYSTEM
8/9/2019 Diff Point
14/32
INTRODUCTION
MPFI- a technology used in petrol engines
Uses a small computer to control the car’s engine
In MPFI engine one fuel –injector is installednear each cylinder ,that is why it is called multi
point fuel injection.
Before MPFI system, there was a technology
called “Carburetor” .
8/9/2019 Diff Point
15/32
The computer in the MPFI system decides what
amount of fuel to inject
System also learns from the drivers driving
habits
MPFI system makes engine fuel efficient .
8/9/2019 Diff Point
16/32
MAIN COMPONENTS OF MPFI SYSTEM
This system has four major components they are:
a) Air intake system
i. Throttle body
ii. Idle air control valve
b) Fuel delivery system
iii. Fuel pump
iv. Pressure regulator system
v. Injector
c) Electronic control system
vi. Engine Control Module (ECM)
vii. On-Board diagnostic system
8/9/2019 Diff Point
17/32
AIR INTAKE SYSTEM
The air (corresponding to the throttle valve
opening) is filtered by the air cleaner, passes
through the throttle body, and is distributed by
the intake manifold and finally drawn into each
combustion chamber. When the lAC valve isopened according to the signal from ECM, the air
bypasses the throttle valve through bypass
passage and is finally drawn into the intake
manifold.
8/9/2019 Diff Point
18/32
FUEL DELIVERY SYSTEM
The fuel in the fuel tank is pumped up by the
fuel pump, filtered by fuel filter and fed under
pressure to each injector through the delivery
'pipe. As the fuel pressure applied to the injector
is always kept a certain amount higher than thepressure in the intake manifold by the fuel
pressure regulator, the fuel is injected into the
intake port of the cylinder head when the injector
opens according to the injection signal formECM. The fuel relieved by the fuel pressure
regulator return through the fuel return to the
fuel tank.
8/9/2019 Diff Point
19/32
INJECTORS
The opening of the injector is controlled by the vehicles ECU
The injector is supplied with the battery voltage via a relay,
the earth circuit is controlled by the ECU
When the circuit is completed by the ECU a solenoid
operates, the injector valve opens, fuel is then able to be
sprayed into the inlet manifold
The valve moves roughly 1.5-10 milliseconds. This is known
an injector duration or opening time
The ECU will make amendments to the duration depending
on engine temperature, loading air temperature and batteryvoltage
8/9/2019 Diff Point
20/32
THE ROLE OF THE INJECTORS
The injector delivers a finely atomized spray of
fuel into the inlet port
The injectors also vary the amount of fueldelivered to suit the engines conditions
The spray is obtained by passing fuel (that is
pressurised) through the nozzle of the injector
It is located in the inlet manifold near the cylinder
head intae port
8/9/2019 Diff Point
21/32
TYPES OF INJECTORS
1. Pintle Type Injector-Offers good
atomization of fuel.
Prone to deposit build up on the Pintle
valve (deposits can reduce the amount offuel flow, and therefore the vehicle will
run leaner than recommended.
2.Hole type injector- Fuel is delivered
through holes drilled in a director plate at
the injector tip.
Offers good fuel atomization and gives
better resistance to deposit build-up.
8/9/2019 Diff Point
22/32
The injector is placed on the
side of the intake manifold
near the intake port
Every cylinder is providedwith an injector in its intake
manifold .
8/9/2019 Diff Point
23/32
ELECTRONIC CONTROL SYSTEM
The electronic control system consist of various
sensors which detect the stateofengine and
driving conditions, ECM which controls various
devices according tothesignals from the sensors
and Various controlled devices. The systems are Fuel injection control
system
Idle speed control system
Fuel pump control system,
Ignition control system,
Radiator fan control system,
8/9/2019 Diff Point
24/32
ELECTRONIC CONTROL UNIT’S
CHIP
8/9/2019 Diff Point
25/32
WORKING
Injection nozzle atomizes fuel into very small
droplets.
Achieved by providing loaded valve needle forcing
out fuel through small orifice.
Nozzle valve seats on conical seating due to
spring pressure on spindle.
Spring pressure is suitably adjusted by adjusting
screw to give correct opening pressure to fuel.
8/9/2019 Diff Point
26/32
Fuel enters to passage drilled in nozzle holder and
flows to an annular groove around needle seat.
The needle (nozzle) valve is then lifted against spring
pressure to allow high pressure fuel to flow into
combustion chamber.
Nozzle valve closes when fuel pressure becomes less
than spindle spring pressure.
Extra fuel going up to nozzle spindle is carried away
through leak-off pipe to fuel tank.
8/9/2019 Diff Point
27/32
8/9/2019 Diff Point
28/32
FUNDAMENTALS OF FUEL
INJECTION
MPFI Systems can either be: Sequential Simultaneous Group
These techniques result in better ‘power
balance’ amongst the cylinders, higher
output from each one of them, along
with faster throttle response.
8/9/2019 Diff Point
29/32
TYPES OF MPFI SYSTEMS
Simultaneous injectors will operate all (or groups of
injectors) at the same time
Sequential will operate independently and open and
close at different times (determined by the ECU)Group used in cylinder pairs [in V-series engines]
8/9/2019 Diff Point
30/32
'Sequential' is the best from the above
considerations of power balance/output
“Sefi’’-Sequential Electronic Fuel Injection -
technically is the best of the above variants ofMPFI
The ‘on-board’ ECU primarily controls the
Ignition Timing and quantity of fuel to be
injected .
8/9/2019 Diff Point
31/32
ADVANTAGES OF MPFI1. Improved fuel consumption
2. Better for the environment
3. Better performance.
4. Immediate response, in case of sudden acceleration / deceleration.
5. No need to crank the engine twice or thrice in case of cold starting as
happens in the carburetor system.
6. More uniform A/F mixture will be supplied to each cylinder; hence the
difference in power developed in each cylinder is minimum. Vibration
from the engine equipped with this system is less, due to this the life of
engine components is improved.
8/9/2019 Diff Point
32/32
THANK-
YOU
Top Related