Marine Engineering-Alex: Fuel Injection

What IS fuel injection?

Fuel injection is a system for mixing fuel with air in an internal combustion engine. It has become the primary fuel delivery system used in automotive engines, having almost completely replaced carburettors in the late 1980s.

Image from: http://upload.wikimedia.org/wikipedia/commons/f/f8/Jeep_2.5_liter_4-cylinder_engine_chromed_i.jpg

Info from: http://en.wikipedia.org/wiki/Fuel_injection

Who Invented fuel injection and when?

Herbert Akroyd Stuart developed the first system laid out on modern lines (with a highly-accurate 'jerk pump' to meter out fuel oil at high pressure to an injector. This system was used on the hot bulb engine and was adapted and improved by Robert Bosch for use on diesel engines.

Image of Herbert Akroyd Stuart found at: http://upload.wikimedia.org/wikipedia/en/2/29/Herbert_Akroyd_Stuart.jpg

The first use of direct gasoline injection was on the Hesselman engine invented by Swedish engineer Jonas Hesselman in 1925.

Info from: http://en.wikipedia.org/wiki/Fuel_injection#History_and_development

The Hesselman engine is a hybrid between a petrol engine and a Diesel engine.

Image from: http://cdn.dipity.com/uploads/events/f575514d4740ff705203078f0595fa0e_1M.png

Info from: http://en.wikipedia.org/wiki/Hesselman_engine

What does EFI stand for?

EFI stands for: Electronic fuel injection, internal combustion engine technology.

Info from: http://en.wikipedia.org/wiki/EFI#Technology

What is an ECU and how does it work?

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 performance maps (so called LUTs), using input values (e.g. engine speed) calculated from signals coming from sensor devices monitoring the engine. Before ECU's, air/fuel mixture, ignition timing, and idle speed were directly controlled by mechanical and pneumatic sensors and actuators.

Info from: http://en.wikipedia.org/wiki/Engine_control_unit

Image from: http://www.team-integra.net/images/BAEC1978-D3A7-4405-AB2D-2761DC15A96D/articles/tuan/p73A0ECU-retry.jpg

Mass Air Flow Sensor-What it is and how it works

A mass air flow sensor is used to find out the mass of air entering a fuel-injected internal combustion engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude and use of forced induction and this is an ideal application for a mass sensor.

Info from: http://en.wikipedia.org/wiki/Mass_flow_sensor

Image from: http://upload.wikimedia.org/wikipedia/commons/e/e8/Mass-airflow.jpg

Air Tem Sensor:

An air temperature sensor is used on fuel injected engines. The purpose of an air temperature sensor is to help the computer calculate air density. A change in temperature changes the resistance in the sensor. Simply stated, the higher the air temperature gets the less dense the air becomes. As the air becomes less dense the computer knows that it needs to lessen the fuel flow. If the fuel flow was not changed the engine would become rich, possibly losing power and consuming more fuel.

Info and image from: http://www.freeengineinfo.com/air-temp-sensor.htm

Throttle Position Switch-What it is and how it works:

A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the throttle valve butterfly. The senor is usually a potentiometer, and therefore provides a variable resistance dependent upon the position of the valve (and hence throttle position).

The sensor signal is used by the engine control unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburettor systems).

Info from: http://en.wikipedia.org/wiki/Throttle_position_sensor

Image from: http://moodle.student.cnwl.ac.uk/moodledata_shared/CDX%20eTextbook/dswmedia/images/throttlesensors.jpg

Throttle body:

A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (i.e., by the use of a throttle), but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which the power or speed of an engine is regulated.

Info from: http://en.wikipedia.org/wiki/Throttle

Image from: http://image.nengun.com/catalogue/original/nengun-1620-02-fujitaengineering-throttle_body.jpg

The temperature sensor

An ECT sensor, or Engine Coolant Temperature Sensor is a sensor that is screwed into the engine's block or cylinder head and is used to determine the temperature of the engine coolant. The ECT sensor is basically a thermistor that changes resistance with temperature. When the ECT (engine coolant temperature) is high (hotter), the resistence is low, and when the ECT is low (cooler) the resistence is high. This resistance reading is sent to the vehicle's PCM/ECM (car's onboard computer) and is or can be used to activate emission controls or turn the engine's cooling fan on.

Info form: http://www.obd-codes.com/faq/ect-sensor.php

Image from: http://www.obd-codes.com/faq/ect-sensor.php

Fuel Rail:

A fuel rail is essentially a pipe (usually resembling a rail) used to deliver fuel to individual fuel injectors on internal combustion engines. It is designed to have a pocket or seat for each injector as well as an inlet for a fuel supply. Some fuel rails also incorporate an attached fuel pressure regulator. Fuel rails are used on engines with multi-point fuel injection systems, although some multi-point systems use a fuel distributor with individual pipes or tubes to feed each injector.

Info from: http://en.wikipedia.org/wiki/Fuel_rail

Image from: http://upload.wikimedia.org/wikipedia/en/f/f4/Fuel_rail.JPG

Fuel pressure regulator:

The installation of an aftermarket fuel pressure regulator allows for the adjustment of fuel pressure to suit larger aftermarket injectors and other engine modifications. They are also necessary to regulate and flow increased volumes of fuel pumped by high flow aftermarket fuel pumps. Fuel pressure regulators work with the fuel pump to maintain a steady pressure relationship between the fuel line side of the injectors and the intake manifold.

Info from: http://www.xspeed.com.au/tech_features.php?tech_id=24

Image from: http://www.mvagusta.net/forum/attachment.php?attachmentid=44031&stc=1&d=1299150472

Injectors:

An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermo-compressor is a pump-like device that uses the Venturi effect of a converging-diverging nozzle to convert the pressure energy of a motive fluid to velocity energy which creates a low pressure zone that draws in and entrains a suction fluid.

Info from: http://en.wikipedia.org/wiki/Injector

converging-diverging nozzle- A convergent-divergent nozzle, is a tube that is pinched in the middle, making a carefully balanced, asymmetric hourglass-shape. It is used to accelerate a hot, pressurised gas passing through it to a supersonic speed, and upon expansion, to shape the exhaust flow so that the heat energy propelling the flow is maximally converted into directed kinetic energy.

Info from: http://en.wikipedia.org/wiki/De_Laval_nozzle

Image from: http://upload.wikimedia.org/wikipedia/commons/b/b4/Ejector_or_Injector.png

Idle Air Control:

An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or PCM (power train control module) receives information from various sensors and will output signals to adjust the idle air control motor in or out to adjust engine idle speed by controlling engine idle air.

Info from: http://www.2carpros.com/articles/how-a-idle-air-control-valve-works

Image from: http://www.2carpros.com/articles/how-a-idle-air-control-valve-works

Oxygen sensor:

An oxygen sensor, or lambda sensor, is an electronic device that measures the proportion of oxygen (O₂) in the gas or liquid being analyzed. Lambda probes are used to reduce vehicle emissions by ensuring that engines burn their fuel efficiently and cleanly. The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. (e.g. An output voltage of 0.2 V (200 mV) DC represents a "lean mixture" of fuel and oxygen and An output voltage of 0.8 V (800 mV) DC represents a "rich mixture".

Info from: http://en.wikipedia.org/wiki/Oxygen_sensor

Image from: http://cf.blogetery.com/65254/files/2010/01/o2-sensors.jpg

MAP Sensor:

The Manifold Absolute Pressure sensor (MAP sensor) is one of the sensors used in an internal combustion engine's electronic control system. Engines that use a MAP sensor are typically fuel injected. The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion.

Info from: http://en.wikipedia.org/wiki/MAP_sensor

Image from: http://journal.alone.cl/wp-content/uploads/2010/06/map.jpg

Plenum chamber:

A plenum chamber is a pressurised housing containing a gas or fluid (typically air) at positive pressure (pressure higher than surroundings). One function of the plenum can be to equalise pressure for more even distribution, because of irregular supply or demand. A plenum chamber can also work as an acoustic silencer device.

Info from: http://en.wikipedia.org/wiki/Plenum_chamber

Image from: http://www.professional-products.com/images/manifold/Imports/honda59000b.jpg

Crank & Camshaft sensors:

Crank sensors in engines usually consist of magnets and an inductive coil, or they may be based on magnetically triggered Hall effect semiconductor devices. Common mounting locations include the main crank pulley, the flywheel, and occasionally on the crankshaft itself. This sensor is the most important sensor in modern day engines. The crank sensor can be used in combination with a similar camshaft position sensor to monitor the relationship between the pistons and valves in the engine, which is particularly important in engines with variable valve timing. It is also commonly the primary source for the measurement of engine speed in revolutions per minute.

Info from: http://en.wikipedia.org/wiki/Crank_sensor