GOVERNMENT ENGINEERING COLLEGE
RAMANAGARA
AFFILIATED TO VTU
Department of Mechanical Engineering
Technical Seminar Topic on
“MULTIPOINT FUEL INJECTION SYSTEM”
Presented by
DHANRAJ V (1GG20ME407)
Under the Guidance of Head of Department
Dr.Irappa Hunagund Dr. D Madhu
CONTENTS
•INTRODUCTION
•OBJECTIVES
•COMPONENTS OF MPFI AIR INTAKE SYSTEM
•PRESSURE REGULATOR SYSTEM
•CONTROL SYSTEM
•FUEL PUMP CONTROL SYSTEM
•WORKING
•FUNCTIONAL DIVISIONS OF MPFI SYSTEM
•ADVANTAGE AND DISADVANTAGE
•CONCLUSION
INTRODUCTION
• In petrol vehicles carburetor is used for supplying air fuel
mixture to the cylinder.
• In response to the recent demand for cleaner exhaust emission
improved drivability and mileage carburetor is not sufficient.
• In place of the carburetor MPFI system is used in vehicles.
• MPFI system injects fuel into individual cylinders based on
commands from engine control module.
• The MPFI gives higher output, faster throttle response under
varying driving conditions.
OBJECTIVES
There are several competing objectives such as:
o To get better Power output.
o To achieve Fuel efficiency.
o Emissions performance.
o Ability to accommodate alternative fuels.
o Reliability.
o Drivability and smooth operation.
COMPONENTS OF MPFI
The system has four major components they are
1.Air intake system
2.Fuel delivery system
3.Electronic control system
4.Emission control system
Air intake system :
It includes air filter, throttle body, intake manifold, and finally drawn into the
combustion chamber.
• Throttle body
o It consist of throttle valve, Throttle position
sensor, which detect the valve opening.
o Idle air control valve which supplies bypass
air depending on the engine condition.
• Fuel delivery system
It includes :
o Fuel pump
o Fuel filter and
o Injector
Fuel Pump
The electrical fuel pump located on the fuel pump consists of
armature, magnet, impeller, brush, check valve etc...The ECM
controls its operation. When the power is supplied to the fuel pump,
the motor in the pump runs and it supply the fuel.
• Pressure regulator system
It keep the fuel pressure applied to the injector 2.9kg/cm^2(2.843
Bar).
The fuel pressure regulator is a pressure relief valve that consist of a
spring, diaphragm and a valve.
• Injector
Each cylinder have one injector.
Injector is a electromagnetic type injection nozzle
that perform its works according to the signal.
•Electronic control system
The electronic control system consist of various sensors which
detect the state of engine and driving conditions.
•Control systems
•Fuel injection control system :
o In which ECM controls the timing of fuel injection according
to the signals from various sensors.
o Injection time is calculated on the basis of engine speed.
• Idle speed control system :
o This system controls the bypass airflow by means of ECM
following . To keep the engine idle speed as specified at all
times.
o To improve starting performance of the engine to compensate
air fuel mixture ratio when decelerating, to improve drivability
while engine is warmed up.
• Fuel pump control system :
o ECM controls ON/OFF operation of the fuel pump by turning
it ON, the fuel pump relay under any of the conditions. While
crankshaft position sensor or camshaft - position sensor signal
is inputted to ECM.
• Ignition control system
o This system controls ignition timing.
o The ECM judges the engine conditions by using signals from
various sensors selects suitable Ignition timing.
o Controls of this system includes Ignition timing at the engine
start.
WORKING
• The MPFI system consists of one fuel injector placed near every
intake valve and directed towards it, in the fuel intake manifold.
• Fuel is supplied to the injector through a common rail. The amount of
air intake is decided by the car driver by pressing the gas pedal,
depending on the speed requirement.
• The air mass flow sensor near throttle valve and the oxygen sensor in the
exhaust sends signal to ECU. ECU determines the air fuel ratio
required ,hence the pulse width. Depending on the signal from ECU the
injectors inject fuel right into the intake valve. The fuel sprayed at high
pressure
gets atomized into fine particles and get mixed with air. The air fuel
mixture is sucked into the engine cylinder and the combustion takes place.
The things which can be known from the sensors are listed below:
o The engine temperature of the vehicle.
o The speed at which the engine is running.
o The engine load.
o The position of the accelerator.
o The cylinder's air-fuel pressure.
o The rate of exhaust. The amount of fuel to be injected into the combustion
chamber is decided by analyzing the inputs given to the computerized
system of the MPFI engine
ADVANTAGES
•Improves durability and functionality of an engine
•More uniform air-fuel mixture will be supplied to each cylinder, hence the
difference in power developed in each cylinder is minimum.
•The vibrations produced in MPFI engines is very less, due to this life of the
engine component is increased.
• No need to crank the engine twice or thrice in case of cold starting as happen
in the carburetor system.
• Immediate response, in case of sudden acceleration and deceleration.
• The mileage of the vehicle is improved.
•More accurate amount of air-fuel mixture will be supplied in these injection
system. As a result complete combustion will take place.
DISADVANTAGES
•Misfiring might occur sometimes
•It requires regular inspection of fuel injectors
•The system is expensive compared to conventional systems.
•Repairing fuel injector can be tedious compared to carburetors
•The system usually has a shorter life.
•ECU failure could occur suddenly.
THANK YOU
