In engine and aircraft engineering, the fuel gauge or gas gauge is an instrument used to indicate the amount of fuel in the fuel tank.
Video Fuel gauge
Motor vehicles
As used in a vehicle, the measuring instrument consists of two parts:
- Sensing unit - inside the tank
- Indicators - on the dashboard
The sensing unit typically uses a float connected to a potentiometer, an ink design usually printed in a modern car. When the tank empties, the float falls and shifts the contacts moving along the resistor, increasing its resistance. In addition, when the resistance is at a certain point, it will also turn on the "low fuel" light on some vehicles.
Meanwhile, the indicator unit (usually mounted on the dashboard) measures and displays the amount of electric current flowing through the sending unit. When the tank level is high and the maximum current flows, the needle points to "F" indicating the full tank. When the tank is empty and the current is at least flowing, the needle points to "E" indicating an empty tank.
The system can fail-safe. If an electric error is open, the electrical circuit causes the indicator to show the empty tank (theoretically provoking the driver to refill the tank) rather than full (which will allow the driver to run out of fuel without prior notice). Corrosion or wear from a potentiometer will give the wrong fuel level readings. However, this system has potential risks associated with it. The electric current is sent through the variable resistor to which the buoy is connected, so the resistance value depends on the fuel level. In most automotive fuel gauges, the resistors are on the inner side of the gauge, ie inside the fuel tank. Sending current through the resistor has a fire hazard and the risk of explosion associated with it. This resistance sensor also shows an increased rate of failure with the addition of additional alcohol in automotive gasoline. Alcohol increases the corrosion rate at the potentiometer, as it is capable of carrying currents like water. Potentiometer applications for alcohol fuel use pulse and grasp methodologies, with periodic signals being sent to determine fuel levels that reduce corrosion potential. Therefore, the demand for other, more secure and non-contact methods for desired fuel levels.
Maps Fuel gauge
Aircraft
The fuel level sensor of the solaroresistance type, now becoming common in small aircraft applications, offers a potential alternative to automotive use. This fuel-level sensor works similar to a potentiometer sample, but the sealed detector in the floating pivot determines the angle position of a pair of magnets at the end of the pivot of the buoy arm. It's very accurate, and the electronics are completely beyond fuel. The non-contact nature of these sensors overcomes the dangers of fire and explosion, as well as problems associated with a combination of fuel or additives for gasoline or alcohol fuel mixtures. Magneto resistive sensors are suitable for all combinations of fuel or liquids, including LPG and LNG. The fuel level output for this sender can be either the preferred ratiometric voltage or digital CAN bus. These sensors are also not safe because they provide output level or not at all.
Systems that measure large fuel tanks (including underground storage tanks) can use the same electro-mechanical principle or perhaps use pressure sensors, sometimes connected to a mercury manometer.
Many large transport planes use different fuel gauge design principles. An aircraft can use a number (about 30 on the A320) from a low voltage probe tube capacitor where the fuel becomes dielectric. At different fuel levels, different capacitance values ​​are measured and therefore fuel levels can be determined. In the initial design, the profile and value of the individual probes were selected to compensate for the fuel tank shape and the pitch and roll attitude of the aircraft. In more modern aircraft, the probe tends to be linear (capacitance is proportional to the height of the fuel) and the fuel computer works how much fuel there is (slightly different at different manufacturers). It has the advantage that the wrong probe can be identified and removed from the fuel calculation. In total this system can be more than 99% accurate. Since most commercial aircraft use only the board fuel required for the intended flight (with an appropriate safety margin), the system allows the fuel load to be pre-selected, causing fuel deliveries to be shut down when the intended load has been taken onboard.
See also
- Floating switch
- Visibility glass
External links
- Explanation of double drip iron indicator operation
Note
Source of the article : Wikipedia
0 Comments