Motor vehicle fuel level sensor

Abstract

Disclosed herein is a fuel sensor suited for sensing the level of fuel in a motor vehicle fuel tank. The fuel tank includes an interior mounting to which the fuel sensor is affixed. The fuel sensor has a cantilever member extending in a substantially horizontal direction from the mounting to a free end. The cantilever member is substantially rigid but can be deflected in the vertical direction. A probe is affixed at the free end of the cantilever member to extend in a substantially vertical orientation approximately the full height of the fuel tank. A stabilizer member is affixed at one end to the mounting and at an opposing end to the probe. The stabilizer member has a pivot segment between the ends permitting the probe to move vertically but not horizontally. According to Archimedes's principle, the probe encounters a buoyant force equal to the weight of displaced fuel which induces strain in the cantilever member. The strain is detected by a strain gauge rigidly coupled to a surface of the cantilever member. The strain gauge produces a resistance that causes a voltage difference across the strain gauge, when a voltage is applied. This voltage difference is calibrated to indicate the level of fuel in the fuel tank. The probe is lightweight such that it is highly sensitive to small variations in fuel level. Additionally, the sensor include probes of various profiles such that it can be adapted to provide a linear fuel level reading in automobile fuel tanks with irregular profiles.