At different fuel levels, different values of capacitance are measured and therefore the level of fuel can be determined. An aircraft may use a number (around 30 on an A320) of low voltage tubular capacitor probes where the fuel becomes the dielectric. Many large transport aircraft use a different fuel gauge design principle. Systems that measure large fuel tanks (including underground storage tanks) may use the same electro-mechanical principle or may make use of a pressure sensor, sometimes connected to a mercury manometer. These sensors also fail-safe in that they either provide a level output or nothing. The fuel level output for these senders can be ratiometric voltage or preferable CAN bus digital. Magneto resistive sensors are suitable for all fuel or fluid combinations, including LPG and LNG. The non-contact nature of these sensors address the fire and explosion hazard, and also the issues related to any fuel combinations or additives to gasoline or to any alcohol fuel mixtures. These are highly accurate, and the electronics are completely outside the fuel. These fuel level sensors work similar to the potentiometer example, however a sealed detector at the float pivot determines the angular position of a magnet pair at the pivot end of the float arm. Magnetoresistance type fuel level sensors, now becoming common in small aircraft applications, offer a potential alternative for automotive use. Other automotive companies noticed the addition and began to incorporate it into their own fuel gauges. After he proposed the idea, the 1989 Ford Escort and Mercury Tracer were the first vehicles to see it implemented. The use of the icon and arrow was invented in 1986 by Jim Moylan, a designer for Ford Motor Company. Since the early 1990s, many fuel gauges have included an icon with a fuel pump and an arrow, indicating the side of the vehicle on which the fuel filler is located.
Therefore, demand for another safer, non-contact method for fuel level is desired. Potentiometer applications for alcohol fuel use a pulse-and-hold methodology, with a periodic signal being sent to determine fuel level decreasing the corrosion potential. Alcohol increases the corrosion rate at the potentiometer, as it is capable of carrying current like water. These resistance sensors are also showing an increased failure rate with the incremental additions of alcohol in automotive gasoline fuel.
Sending current through such a resistor has a fire hazard and an explosion risk associated with it. In most automotive fuel gauges such resistors are on the inward side of the gauge, i.e., inside the fuel tank. An electric current is sent through the variable resistor to which a float is connected, so that the value of resistance depends on the fuel level. However, this system has a potential risk associated with it. Corrosion or wear of the potentiometer will provide erroneous readings of fuel level.
Car fuel gauge simulator recorder driver#
If an electrical fault opens, the electrical circuit causes the indicator to show the tank as being empty (theoretically provoking the driver to refill the tank) rather than full (which would allow the driver to run out of fuel with no prior notification). Typical old-style fuel gauge on a 50 ccm chinese-made scooter from 2008, with the internationally used pictogram of a gas pump When the tank is empty and the least current is flowing, the needle points to "E" indicating an empty tank some vehicles use the indicators "1" (for full) and "0" or "R" (for empty) instead. When the tank level is high and maximum current is flowing, the needle points to "F" indicating a full tank. Meanwhile, the indicator unit (usually mounted on the dashboard) is measuring and displaying the amount of electric current flowing through the sending unit. In addition, when the resistance is at a certain point, it will also turn on a "low fuel" light on some vehicles. As the tank empties, the float drops and slides a moving contact along the resistor, increasing its resistance. The sending unit usually uses a float connected to a potentiometer, typically printed ink design in a modern automobile. The chart below shows the various electrical gauge options available and the sender required for each.An analog fuel gauge in a 2016 Toyota Corolla featuring a "Moylan Arrow" indicating a fuel filler on the left side of the vehicle.Īs used in vehicles, the gauge consists of two parts: Raceparts stock a wide range of Racetech electrical gauges. Gauges › Electrical Gauges Electrical Gauges
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