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Title: Gasoline electronic Direct Injection System prepared by:


1
Gasoline electronic Direct Injection System
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2
Gasoline electronic Fuel Injection Systems
3
Introduction
  • A modern gasoline injection system uses pressure
    from an electric fuel pump to spray fuel into the
    engine intake manifold. Like a carburetor, it
    must provide the engine with the correct air-fuel
    mixture for specific operating conditions.    Unli
    ke a carburetor, however, PRESSURE, not engine
    vacuum, is used to feed fuel into the engine.
    This  makes  the  gasoline  injection system
     very  efficient

4
  • A gasoline injection system has several possible
    advantages over a carburetor type of fuel
    system.  
  • Some advantages  are  as  follows
  • Improved atomization. Fuel is forced into the
    intake manifold under pressure that helps break
    fuel droplets into a fine mist.
  • Better fuel distribution. Equal flow of fuel
    vapors  into  each  cylinder.
  • Smoother idle. Lean fuel mixture can be used
    without rough idle because of better fuel
    distribution and  low-speed  atomization.

5
  • Lower  emissions.  Lean  efficient  air-fuel
     mixture reduces exhaust pollution.
  • Better  cold  weather  drivability.  Injection
    provides better control of mixture enrichment
    than a carburetor.
  • Increased  engine  power.  Precise  metering
     of fuel to each cylinder and increased air flow
    can result in more horsepower output.
  • Fewer parts. Simpler, late model, electronic
    fuel injection  system  have  fewer  parts  than
     modern computer-controlled  carburetors.

6
There are many types of gasoline injection
systems. Before studying the most common ones,
you should have A basic knowledge of the
different classifications
single- or multi-point injection
indirect or direct injection
7
  • The point or location of fuel injection is one
    way to classify a gasoline injection system. A
    single-point injection  system,  also  call
     throttle  body  injection  (TBI), has the
    injector nozzles in a throttle body assembly on
    top of the engine. Fuel is sprayed into the top
    center of the  intake  manifold .

8
  • A multi-point  injection  system,  also  called
     port injection, has an injector in the port
    (air-fuel passage) going to each cylinder.
    Gasoline is sprayed into each intake port and
    toward each intake valve. Thereby, the term
     multipoint (more  than  one  location) fuel
     injection is used.

9
  • An indirect injection system
    sprays fuel into the
    engine  intake  manifold.  
    Most  gasoline  injection
    systems are of this
    type.
  • Direct injection forces fuel
    into the engine combustion
    chambers. Diesel
    injection systems
    are direct type.
  • So
  • Gasoline electronic Direct Injection System
  • is Classified as multi-point and Direct
    injection systems


10
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11
System component
  • Fuel tank
  • Electric fuel pump
  • Fuel filter
  • Electronic control unit
  • Common rail and Pressure sensor
  • Electronic Injectors
  • fuel line

12
Fuel tank
  • is safe container for flammable liquids and
    typically part of an engine system in which the
    fuel is stored and propelled (fuel pump) or
    released (pressurized gas) into an engine.
  • Typically, a fuel tank must allow or provide the
    following
  • Safe (UL Approved) fuel storage, there is some
    concern that UL (Underwriters Laboratories) is
    not the final arbiter of safety.
  • Filling (the fuel tank must be filled in a
    secure way) No Sparks.
  • Storage of fuel (the system must contain a
    given quantity of fuel and must avoid leakage and
    limit evaporative emissions)

13
  • Provide a method for determining level of fuel
    in tank, Gauging (the remaining quantity of fuel
    in the tank must be measured or evaluated)
  • Venting (if over-pressure is not allowed, the
    fuel vapors must be managed through valves)
  • Feeding of the engine (through a pump)
  • Anticipate potentials for damage and provide
    safe survival potential.

14
Electric fuel pump
  • An electric fuel pump is used on engines with
    fuel injection to pump fuel from the tank to the
    injectors. The pump must deliver the fuel under
    high pressure (typically 30 to 85 psi depending
    on the application) so the injectors can spray
    the fuel into the engine.
  • Electric fuel pumps are usually mounted inside
    the fuel tank,
  • Some vehicles may even have two fuel pumps (a
    transfer pump inside the tank, and a main fuel
    pump outside).

15
  • Electric fuel pumps come in a variety of designs.
    Some older applications use a positive
    displacement "roller cell" pump. This type uses
    rollers mounted on an offset disc that rotates
    inside a steel ring. Fuel is drawn into the
    spaces (cells) between the rollers and pushed
    along from the pump inlet to the outlet. This
    type of pump can generate very high pressure, and
    the flow rate tends to be constant. But the
    output comes in pulses, so a muffler is often
    mounted in the fuel line after the pump to dampen
    pressure pulses. A roller cell pump may also be
    mounted outside the fuel tank, and used with a
    second low pressure supply pump mounted inside
    the fuel tank.

16
  • Most newer vehicles use a "turbine" style fuel
    pump. A turbine pump has an impeller ring
    attached to the motor. The blades in the impeller
    push the fuel through the pump as the impeller
    spins. This type of pump is not a
    positive-displacement pump, so it produces no
    pulsations, runs very smoothly and quietly. It is
    also less complicated to manufacture and is very
    durable. Some aftermarket pump supplies use this
    type of pump to replace the older designs.

17
Fuel filter
  • The fuel filter is the fuel system's primary line
    of defense against dirt, debris and small
    particles of rust that flake off the inside of
    the fuel tank .
  • many filters for fuel injected engines trap
    particles as small as 10 to 40 microns in size.
  • fuel filter normally made into
  • cartridges containing a filter paper.

18
Electronic control unit
  • In automotive electronics, electronic control
    unit (ECU) is a generic term for any embedded
    system that controls one or more of the
    electrical systems or subsystems in a motor
    vehicle.
  • An engine control unit (ECU), also known as
    power-train control module (PCM), or engine
    control module (ECM) is a type of electronic
    control unit that determines the amount of fuel,
    ignition timing and other parameters an internal
    combustion engine needs to keep running. It does
    this by reading values from multidimensional maps
    which contain values calculated by sensor devices
    monitoring the engine.

19
Working of ECU
  • Control of fuel injection ECU will determine the
    quantity of fuel to inject based on a number of
    parameters. If the throttle pedal is pressed
    further down, this will open the throttle body
    and allow more air to be pulled into the engine.
    The ECU will inject more fuel according to how
    much air is passing into the engine. If the
    engine has not warmed up yet, more fuel will be
    injected .
  • Control of ignition timing A spark ignition
    engine requires a spark to initiate combustion in
    the combustion chamber. An ECU can adjust the
    exact timing of the spark (called ignition
    timing) to provide better power and economy.

20
  • Control of idle speed Most engine systems have
    idle speed control built into the ECU. The engine
    RPM is monitored by the crankshaft position
    sensor which plays a primary role in the engine
    timing functions for fuel injection, spark
    events, and valve timing. Idle speed is
    controlled by a programmable throttle stop or an
    idle air bypass control stepper motor.

21
Common rail and Pressure sensor
  • The term "common rail" refers to the fact that
    all of the fuel injectors are supplied by a
    common fuel rail which is nothing more than a
    pressure accumulator where the fuel is stored at
    high pressure. This accumulator supplies multiple
    fuel injectors with high pressure fuel.

22
  • The fuel injectors are typically ECU-controlled.
    When the fuel injectors are electrically
    activated a hydraulic valve (consisting of a
    nozzle and plunger) is mechanically or
    hydraulically opened and fuel is sprayed into the
    cylinders at the desired pressure. Since the fuel
    pressure energy is stored remotely and the
    injectors are electrically actuated the injection
    pressure at the start and end of injection is
    very near the pressure in the accumulator (rail),
    thus producing a square injection rate. If the
    accumulator, pump, and plumbing are sized
    properly, the injection pressure and rate will be
    the same for each of the multiple injection
    events.

23
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24
Electronic Injectors
  • The injectors can survive the excessive
    temperature and pressure of combustion by using
    the fuel that passes through it as a coolant

25
  • The electronic fuel injector is normally closed,
    and opens to inject pressurized fuel as long as
    electricity is applied to the injector's solenoid
    coil.
  • When the injector is turned on, it opens,
    spraying atomized fuel at the combustion chamber
    .
  • Depending on engine operating condition
    ,injection quantity will vary .

26
fuel line
  • Fuel line hoses carry gasoline from the tank to
    the fuel pump, to the fuel filter, and to the
    fuel injection system. While much of the fuel
    lines are rigid tube, sections of it are made of
    rubber hose, which absorb engine and road
    vibrations.
  • There are two basic types of fuel hose Fuel and
    oil hoses that meet the SAE 30R7 standard, and
    fuel injection hose that meets the requirements
    of SAE 30R9.

27
Gasoline direct injection
  • In internal combustion engines, gasoline direct
    injection is a variant of fuel injection employed
    in modern two- and four- stroke petrol engines.
    The petrol/gasoline is highly pressurized, and
    injected via a common rail fuel line directly
    into the combustion chamber of each cylinder, as
    opposed to conventional multi-point fuel
    injection that happens in the intake tract, or
    cylinder port.

28
How system work
29
  • When the driver turns the ignition key on, the
    power train control module (PCM) energizes a
    relay that supplies voltage to the fuel pump. The
    motor inside the pump starts to spin and runs for
    a few seconds to build pressure in the fuel
    system. A timer in the PCM limits how long the
    pump will run until the engine starts.
  • Fuel is drawn into the pump through an inlet tube
    and mesh filter sock
  • The fuel then exits the pump through a one-way
    check valve and is pushed toward the engine
    through the fuel line and filter.

30
  • The fuel filter traps any rust, dirt or other
    solid contaminants that may have passed through
    the pump to prevent such particles from clogging
    the fuel injectors.
  • The fuel then flows to the fuel supply rail on
    the engine and is routed to the individual fuel
    injectors. A fuel pressure regulator on the fuel
    rail maintains fuel pressure, and recirculates
    excess fuel back to the tank.
  • The fuel pump runs continuously once the engine
    starts, and continues to run as long as the
    engine is running and the ignition key is on. If
    the engine stalls, the (PCM) will detect the loss
    of the RPM signal and turn the pump off.

31
Finally
  • what is Fuel Injection? it describes the way the
    fuel (usually a liquid fuel) is injected (pumped
    under pressure) into some part of the engine
    where it can combine with the air charge in the
    cylinders and combustion can take place,
    releasing energy to propel the vehicle.
  • Whats different about diesel CI engine
    injection?
  • Diesel (compression ignition or CI ) and
    petrol/gasoline (spark ignition or SI ) engines
    go about the task of releasing energy from their
    fuels in quite different ways.

32
  • In fuel-injected spark ignition SI engines,
    fuel is always injected into the air charge well
    before ignition takes place. This necessary
    because the liquid or gaseous fuel must be
    thoroughly mixed together with air into a
    combustible mixture, able to be ignited by the
    electrical arc generated by the sparkplug. If the
    ratio of air to fuel is not reasonably close to
    151 in the vicinity of the sparkplug, the
    mixture will not ignite at all and a miss-fire
    results.

33
  • Compression ignition CI engines always inject
    the fuel charge directly into a combustion
    chamber in the engine. Fuel injection and
    ignition are inextricably tied together in
    compression ignition CI engines. Recall that CI
    engines only work because they compress the air
    charge so that it is hot enough to instantly
    ignite the fuel charge as it is being injected.
    The combustion of the fuel begins at the instant
    it begins being injected (well, within a couple
    of milliseconds, if you want to split hairs) into
    the combustion chamber full of very hot air (more
    than 400 ºC, often over 700 ºC).
  • This means the timing of ignition is intimately
    tied to the fuel injection process. So, the fuel
    injection system of a CI engine is responsible
    for regulating both the quantity of fuel to be
    injected and timing of the beginning of
    combustion. Many ingenious techniques have been
    developed to achieve both these tasks with
    admirable accuracy, long before the advent of
    sophisticated electronic controls.

34
How much fuel are we injecting here?
  • lets do a few simple sums based on 1997 Land
    Rover Discovery. It has a 4 cylinder 2.5 liter
    engine. At 100 km/h in 5th gear its doing very
    close to 2400 rpm or 2400/60 40 revolutions per
    second. Because its a 4 cylinder 4 stroke
    engine, it will be producing 2 power strokes
    every revolution, so thats 80 power strokes per
    second. At a steady cruising speed of 100 km/h,
    it is likely to be covering 10 km/liter or, in
    other words, using 10 litres/100 km. Therefore,
    our fuel burn rate is 10 liters per hour or
    10/3600 0.00278 liters per second 2.78
    mL/sec. Now, this 2.78 mL is shared between the
    80 power strokes of the engine per second. So,
    for each power stroke of the engine while we are
    cruising at 100 km/h, the fuel injection system
    is delivering 2.78/80 0.03472 mL into each
    cylinder. Not much is it? And the injection
    system delivers precisely this quantity of fuel
    to one of the cylinders of the engine, 80 times
    per second and at the exact instant the cylinder
    needs to fire. Not bad for a completely
    mechanical system with no electronic smarts at
    all, is it?

35
How much pressure?
  • SI engine (petrol/gasoline) injection systems
    typically run at pressure of 2 to 3 bar (30 to 40
    psi). In contrast CI (diesel) engines employ
    injection pressures of at least 350 bar (5000
    psi) and possibly in excess of 2000 bar (gt29,000
    psi) quite a bit different to petrol/gasoline
    systems! This explains why CI injection systems
    are so solidly built and piped-up with strong
    steel tubing, etc.
  • Petrol/gasoline readily vaporizes in the air
    stream entering the engines cylinders and in
    contact with the hot cylinder head surfaces, to
    form an easily ignitable air/vapor mixture. On
    the other hand, to instantly ignite the much less
    volatile diesel fuel in the hot air charge of a
    CI engine it is necessary to spray it into the
    combustion chamber in extremely small droplets.
    And to achieve this, extremely high injection
    pressures are required the higher the better,
    in general.
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