Liquid level detection apparatus and other apparatus comprising in common an elongated flexible substrate transducer which can extend into a liquid containing vessel or be applied to other pressure or force measurement tasks and provide an accurate indication of liquid level or other pressure or force related parameter through a voltage drop measurement made through an elongated, e.g., sinuous or other regular pattern (or of irregular patterning to localize areas of highest sensitivity) conductor pattern contained in the transducer which is shorted out in the portion thereof subjected to a predetermined pressure, the elongated conductor being on facing portions of a folded sheet substrate material which has an inherent spring characteristic (resilience) and/or geometrical-arrangement-loading such that the portion thereof subjected to such pressure has butting face portions and the portion thereof not subjected to such pressure is separated due to the spring characteristic of the folded sheet material. For instance, as applied to liquid level measurement, the folded substrate is in elongated ribbon form and the portion below liquid level is subjected to liquid pressure sufficient to move the two facing portions in butting engagement causing elongated conductor patterns thereon to short out at liquid level.
A device for detecting the level of a liquid contained in a tank, for example the level of the fuel contained in the tank of a motor car. The device comprises a vertical bar inserted in the tank and a float movable with respect to the bar to follow the variations in the level. The bar, which is of insulating material, acts as a supporting element for a printed circuit having at least one continuous conductive track and a variable resistor parallel to the continuous track. On the float there is mounted a metal element which simultaneously contacts both the conductive track and the variable resistor.
A device for electrical measurement of the level of a fluid contained in a fuel tank of a motor vehicle is disclosed. In addition to a variable resistance float sensor in a dip tube, a travel sensor is arranged in the dip tube to determine the distance between the dip tube and the bottom of the tank in order to offset measurement errors caused by tolerances in the manufacture of the tank and resultant differences in the mounting position of the dip tube in the tank. The travel sensor includes a spring load rod extending to the bottom of the tank and a variable resistance connected to the rod to produce a calibration value.
A liquid level sensing device utilizing a conductive hollow sphere buoyed by the liquid and guided vertically within a metal tube. An elongated resistance card is mounted in the tube adjacent the sphere to permit the sphere to slide along its surface as the liquid level changes thereby electrically connecting a portion of the resistance card to the metal housing through the conductive sphere. The resistance card is mounted so as to be flexed from its normal flat configuration with the flexed configuration producing a light force on the sphere to maintain good electrical contact therewith and between the sphere and the housing but insufficient to deter the sphere from following liquid level changes.
A flexible circuit film oil sensor includes a flexible circuit film surrounded by a flexible border. A core support flap and a weld flap are attached to opposite ends of the flexible border. The flexible circuit film includes an oil level sensing electrode surface, an oil condition sensing electrode surface, a resistive temperature device, and a common electrode surface. The flexible circuit film engine oil sensor is wrapped around a core structure so that a spiral oil chamber is formed. Accordingly, the spiral oil chamber is at least partially filled with oil and electrical signals are provided across the electrode surfaces in order to monitor the level and condition of oil within the sensor. Additionally, the resistive temperature device provides a signal representative of the temperature of the oil within the sensor.
A three wire potentiometric liquid level sensor for measuring liquid levels in a container is disclosed. The sensor includes a conductive strip, a float, a contact means attached to the float, a resistive strip, and a conductive rod buried beneath an insulator. A second embodiment of the invention includes a first conductive strip, a second conductive strip, a float, a contact means attached to the float, and an insulating rod. The sensor produces a resistance directly proportional to the liquid level in the container.
