Fuel senders in automotive fuel tanks typically consist of a float on the end of a pivot arm, which is connected to a means for providing variable resistance in such a way that, as the float moves up and down on the surface of the fuel, the resistance value of the resistance means changes. A resistor is typically coupled in series with the resistance means and voltage is applied across the circuit. As the resistance of the resistance means changes, the voltage across the resistance means changes. The voltage across the resistance means is used as the sender output signal and is used as an input to a fuel gauge for indicating the amount of fuel in the tank. The fuel gauge is typically a conventional three coil air core gauge with two coils being biased to a set voltage and the third coil being energized in relation to the output signal of the fuel sender. A pointer connected to an axle of a permanent magnet rotor is rotated in relation to the energization of the third coil of the air core gauge.
Because motor vehicles are subject to varying accelerations due to changes in vehicle speeds and direction, fuel in the fuel tank tends to slosh, unless the tank is full. Bumpy roads may also cause the fuel in the tank to slosh. Unless countermeasures are taken, fuel slosh is reflected in the fuel gauge reading as wavering of the gauge pointer, making determination of the actual fuel level difficult for the vehicle operator.
Presently various measures are available to partially reduce the affects of fuel slosh on the fuel reading. One example is the addition of baffles to the fuel tank, increasing the cost of the tank. Another example is damping the response of the gauge with a viscous fluid, slowing the response of the gauge.
Electronic damping of the output signal of the sender can reduce the effects of fuel slosh, reducing or eliminating the requirements of baffles and viscous damping fluid. Further improvements are still sought over conventional electronic damping techniques.