Electrically heated air data sensing device

An air data sensor including a portion exposed to a variable temperature and velocity fluid stream, a heater for said exposed portion comprising a plurality of PTC resistor heaters, a common flexible electrically conductive strip means connecting all of said PTC resistor heaters electrically and mechanically in parallel, a covering of thermally conductive, electrically insulating material over said PTC resistor heaters and said flexible strip means, said covering being in thermal contact with portions of said exposed portion, said flexible conductive strip means being sufficiently flexible to permit the PTC resistor heaters to shift relative to each other under thermally induced expansion.

The method of making an electrically heated air data sensor or the like having a portion exposed to a fluid stream comprising connecting a plurality of individual PTC resistor elements in parallel by bonding the PTC resistor elements to flexible electrically conductive strip means to form an assembly, said strip means being sufficiently flexible to permit the elements to flex relative to each other under thermal gradients, encapsulating the elements and connected strip means assembly with flexible electrically insulating thermally conductive material, and mounting the encapsulated assembly in an air data sensor in position to be in heat conductive relationship to the portion of the air data sensor exposed to a fluid stream.

An electrically heated air data sensing device comprising a movable vane having an elongated portion exposed to a variable temperature fluid, means defining a groove in said vane along substantially the entire exposed portion of the vane, and a heater assembly mounted in and extending along the groove, said heater assembly comprising a plurality of individual PTC heater elements arranged in end to end relationship, said PTC heater elements each having oppositely facing side surfaces, the respective oppositely facing side surfaces of adjacent PTC elements lying along generally parallel common plane, a pair of separate generally flat flexible electrically conductive strips having a plurality of perforations therethrough, electrically conductive bonding means bonding each of the PTC heater elements electrically and mechanically to both of said strips, said strips being sufficiently flexible to permit said PTC elements to shift relative to each other during thermal expansion and contraction, and a flexible, thermally conductive electrically insulating material encapsulating said strips and PTC elements.