|What is Fuel injection
In an internal combustion engine, the fuel
injection system is that which delivers fuel or a fuel-air mixture to the
cylinders by means of pressure from a pump.
It was originally used in
diesel engines because of diesel fuel's greater viscosity and the need to
overcome the high pressure of the compressed air in the cylinders.
fuel injector sprays an intermittent, timed, metered quantity of fuel into a
cylinder, distributing the fuel throughout the air within.
Fuel injection is also now used in
gasoline engines in place of a carburetor.
In gasoline engines the fuel is
first mixed with air, and the resulting mixture is delivered to the
Computers are used in modern fuel injection systems to regulate
The positive effects of fuel injection are that there is more
efficient fuel combustion, better fuel economy and engine performance and
reduced polluting exhaust emissions.
In order to provide the correct amount of fuel for every operating condition,
the engine control unit (ECU) has to monitor a huge number of input sensors.
Here are just a few:
airflow sensor - Tells the ECU the mass of air entering the engine
Oxygen sensor(s) - Monitors the amount of oxygen in the
exhaust so the ECU can determine how rich or lean the fuel mixture is and make
Throttle position sensor - Monitors
the throttle valve position (which determines how much air goes into the
engine) so the ECU can respond quickly to changes, increasing or decreasing the
fuel rate as necessary
Coolant temperature sensor - Allows
the ECU to determine when the engine has reached its proper operating
Voltage sensor - Monitors the system voltage in the car so the
ECU can raise the idle speed if voltage is dropping (which would indicate a
high electrical load)
Manifold absolute pressure sensor -
Monitors the pressure of the air in the intake manifold
The amount of air
being drawn into the engine is a good indication of how much power it is
producing; and the more air that goes into the engine, the lower the manifold
pressure, so this reading is used to gauge how much power is being produced.
Engine speed sensor - Monitors engine speed, which is one of
the factors used to calculate the pulse width
|The " Diesel system "
The " Gasoline system "
This type of internal combustion engine was patented in
1892 by the German engineer Rudolph Diesel.
It burns fuel oil instead of gasoline and is heavier and
more powerful than the gasoline engine.
It differs from the gasoline
engine in that the ignition of fuel is caused by compression of air in its
cylinders instead of by a spark.
By varying the amount of fuel injected in
the cylinder, the speed and power of the diesel are controlled.
and municipal electric generators, continuously operating pumps such as those
used in oil pipelines, and ships, trucks, locomotives, and other such
automobiles widely use diesel to power.