US 4,977,385 A · Distributed RTD

Abstract

An RTD (resistance temperature sensor or detector) sensing device which is a long, thin, unitary device adapted to be distributed across an extended field for the continuous, uninterrupted sensing or interrogation of such field, avoiding the inaccuracy, unreliability, and excessive expense of conventional "point" RTD and thermocouple sensors currently employed for this purpose. According to the invention, a very long, thin, ductile protective metal outer sheath houses a coextensive body of insulation material, which in turn supports and electrically insulates one or more coextensive RTD filaments and in most forms of the invention one or more heater filaments. Distributed RTDs of the invention may, along their lengths, have continuous linear function sensitivity, continuous variable function sensitivity, or step function sensitivity. Distributed RTDs of the invention have particular utility for gauging liquid level, measuring average mass flow velocity of fluids in large ducts, and sensing the average temperature of an extended nonisothermal field.

Claims56

Dependent claims

Distributed RTD sensing means comprising a matched pair of distributed RTD sensing devices each of which is suitable for interrogating an extended field and comprises:

an elongated, thin, tubular outer protective sheath,
an elongated body of electrical insulation material contained within said sheath and extending longitudinally generally coextensively with said sheath,
elongated RTD filament means supported within said insulation body and extending longitudinally within said insulation body and said sheath,
said RTD filament means along its length being physically separated and electrically insulated from said sheath by said insulation body,
said RTD filament means having end means which is electrically connectable to detection circuitry from at least one end of said sheath, and
elongated, electrically energizable heater means supported within said insulation body and extending longitudinally generally coextensively with said RTD filament means,
said heater means along its length being transversely physically separated and electrically insulated by said insulation body from said RTD filament means and from said sheath,
said heater means having end means which is electrically connectable to an electric power source for energization of said heater means,
said matched pair of RTD sensing devices being arranged in a spaced, generally parallel array and deployed over an extended field having nonuniform thermal response characteristics, one of said sensing devices having its said heater means unenergized so that it serves as a thermal reference, and the other of said sensing devices having its said heater means energized so as to be responsive to such characteristics with a signal output which, when compared with the signal output of said unenergized sensing device, provides physical information about said field.

6 more elements

Distributed RTD sensing means comprising at least one RTD sensing device suitable for interrogating an extended field, which comprises:

an elongated, thin, tubular outer protective sheath,
an elongated body of electrical insulation material contained within said sheath and extending longitudinally generally coextensively with said sheath, and
elongated RTD filament means supported within said insulation body and extending longitudinally within said insulation body and said sheath,
said RTD filament means along its length being physically separated and electrically insulated form said sheath by said insulation body,
said RTD filament means having end means which is electrically connectable to detection circuitry from at least one end of said sheath, and
elongated, electrically energizable heater means supported within said insulation body and extending longitudinally generally coextensively with said RTD filament means,
said heater means along its length being transversely physically separated and electrically insulated by said insulation body from said RTD filament means and from said sheath,
said heater means having end means which is electrically connectable to an electric power source for energization of said heater means,
said distributed RTD sensing means being deployed across the inside of a fluid flow duct having nonuniform flow rate distribution, and said distributed RTD sensing means being employed to provide information as to mass flow rate of fluid through said duct.

6 more elements

Dependencies are inferred from the claim text.

Distributed RTD

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Distributed RTD

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Abstract

Claims56