Optical fuel/air/water sensor and detector circuit
AssigneeSimmonds Precision Products, Inc.
InventorsSylvester M. Ellinger, Bruce R. Kline
Life of this patent
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Abstract
A liquid sensing apparatus for a fuel tank comprises a first optical sensor for producing an output having a first state that corresponds to the first optical sensor being exposed to air and a second state that corresponds to the first optical sensor being exposed to fuel; a second optical sensor for producing an output having a first state that corresponds to the second optical sensor being exposed to air or water, and a second state that corresponds to the second optical sensor being exposed to fuel; and a circuit for detecting the first and second optical sensor output states. The sensor circuits can be accessed using a two wire only interface, and thermal stability can be achieved with the electronic circuit as shown.
Claims26
A liquid sensing apparatus for a fuel tank comprising:
- a first optical means for producing an output having a first state that corresponds to the first optical means being exposed to air and a second state that corresponds to the first optical means being exposed to fuel;
- second optical means for producing an output having a first state that corresponds to the second optical means being exposed to water, and a second state that corresponds to the second optical means being exposed to fuel;
- and circuit means for determining said first and second optical means output states.
An electronic circuit for determining the optical output state of a remote optical liquid level detector of the type having a light source, a prism and a light responsive switch that receives light reflected by the prism from the light source based on the interface between the prism and air or liquid, comprising:
- power source means for applying power to the light source, and means for detecting the light responsive switch state based on change in power drawn therefrom, said electronic circuit being connected to the optical detector by no more than two wires.
An optical detector for discriminating between water and aircraft fuel in a fuel tank comprising:
- a prism disposed in the fuel tank, said prism having a frusto-conical tip that receives light from a light source and internally reflects light to a light detector when said tip is exposed to water, and refracts light into aircraft fuel when said tip is exposed to aircraft fuel.
A method for liquid detection in a fuel tank, comprising the steps of:
- a. using a first prism to internally reflect light from a light source to a light detector when the prism is exposed to air, and refracting light away from the detector when the prism is exposed to fuel;
- and
- b. using a second prism to internally reflect light from a light source to a light detector when the second prism is exposed to water, and refracting light away from the detector when the second prism is exposed to fuel.
Apparatus for liquid detection in a fuel tank, comprising:
- first optical means for internally reflecting light from a light source to a light detector when said first optical means is exposed to air, and refracting light away from the detector when said first optical means is exposed to fuel;
- and
- second optical means for internally reflecting light from a light source to a light detector when said second optical means is exposed to water, and refracting light away from the-detector when said second optical means is exposed to fuel.
An electronic circuit for determining the optical output state of a plurality of remote optical liquid level detectors, each detector being of the type having a light source, a prism and a light responsive switch that receives light reflected by the prism from the light source based on the interface between the prism and air or liquids, comprising:
- power source means for applying power to the light sources, and means for detecting the light receptor switches states based on change in power drawn therefrom, said electronic circuit being connected to the plurality of optical detectors by no more than two wires.
Dependencies are inferred from the claim text.