Patent Publication Number: US-2021172973-A1

Title: Hybrid material aircraft sensors and method of manufacturing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 15/988,694 filed May 24, 2018, which claims the benefit of India Patent Application No. 201811010823, filed Mar. 23, 2018, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Exemplary embodiments pertain to the art of aircraft sensors such as pitot tubes, and more particularly to ice prevention and removal from such sensors. 
     A pitot tube is widely used to determine airspeed of an aircraft or other vehicle, or to measure air or gas velocities in industrial applications. In particular, by measuring stagnation pressure of a fluid driven into the pitot tube, together with a measured static pressure, the airspeed of the aircraft can be determined. In certain flight conditions, the pitot tube may be subject to ice accumulation from moisture in the air. For this reason, pitot tubes are equipped with heating elements to prevent such ice accumulation. Further, in other conditions, the pitot tube may ingest ice crystals which then accumulate inside of the pitot tube and cause failure in its operation. A typical pitot tube is substantially cylindrical with an internal diameter containing the heating elements, or coils. Forward of the heating elements is a tip portion that extends radially from forward tip portion to an outer diameter of the pitot tube. An exterior of the typical tube is cylindrical along its length to the inlet. Such a tube has a large surface area of material in the tip portion forward of the heater, and is difficult to heat effectively and therefore to prevent ice accumulation thereon. Further, a large inlet diameter allows for proportionally more ice crystals to be ingested by the pitot tube. Such ingested ice crystals must be melted by the heating elements and drained from the pitot tube. 
     BRIEF DESCRIPTION 
     In one embodiment, an air data probe includes a probe body including a probe wall. The probe body is formed from a first material by direct energy metal deposition. An insert is positioned in the probe wall. The insert is formed from a second material different from the first material. The insert is encapsulated in the probe wall via the direct energy metal deposition. 
     Additionally or alternatively, in this or other embodiments the second material has a higher thermal conductivity than the first material. 
     Additionally or alternatively, in this or other embodiments the second material is one of annealed pyrolytic graphite (APG), graphite or copper. 
     Additionally or alternatively, in this or other embodiments the first material is a nickel or copper alloy material. 
     Additionally or alternatively, in this or other embodiments the insert includes a coating portion of a chromium or nickel material. 
     Additionally or alternatively, in this or other embodiments the insert includes one or more through openings extending therethrough. 
     Additionally or alternatively, in this or other embodiments a coating portion of chromium or nickel material at least partially fills the one or more through holes. 
     Additionally or alternatively, in this or other embodiments the air data probe is one of a pitot tube or a total air temperature probe. 
     In another embodiment, a method of forming an air data probe includes forming one or more thermally conductive inserts, and encapsulating the one or more inserts into a wall of an air data probe via direct energy metal deposition. The air data probe is formed from a first material and the one or more inserts are formed from a second material different from the first material. 
     Additionally or alternatively, in this or other embodiments forming the one or more inserts includes forming a base insert portion and applying a coating portion over the base portion. 
     Additionally or alternatively, in this or other embodiments the base insert portion has a higher thermal conductivity than the first material. 
     Additionally or alternatively, in this or other embodiments the base insert portion is formed from one of annealed pyrolytic graphite (APG), graphite or copper. 
     Additionally or alternatively, in this or other embodiments the coating portion is formed from one of a chromium or nickel material. 
     Additionally or alternatively, in this or other embodiments a suitable heat treatment or hot isostatic pressing is performed the air data probe after encapsulating the one or more inserts. 
     Additionally or alternatively, in this or other embodiments one or more machining operations are performed on the air data probe after encapsulating the one or more inserts. 
     Additionally or alternatively, in this or other embodiments the direct energy metal deposition process is laser metal deposition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is an illustration of an embodiment of a pitot tube; 
         FIG. 2  is a cross-sectional view of an embodiment of a pitot tube; 
         FIG. 3  is a perspective view of an embodiment of an insert for an air data probe; 
         FIG. 4  is a cross-sectional view of an embodiment of an insert for an air data probe; 
         FIG. 5  is another cross-sectional view of an embodiment of an insert for an air data probe; 
         FIG. 6  is a perspective view of an embodiment of a total air temperature probe; 
         FIG. 7  is a partial cross-sectional view of an embodiment of a total air temperature probe; and 
         FIG. 8  is a schematic illustration of a method of forming an air data probe. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIG. 1 , illustrated is an embodiment of a sensor, in this embodiment a pitot tube  10 . The pitot tube  10  includes a cylindrical body portion  12  and a tip portion  14  extending along a tube axis  16  from the body portion  12  toward a tube inlet  18 . In the embodiment of  FIG. 1 , the tip portion  14  includes an inlet opening  20  having an inlet diameter  22  smaller than a body diameter  24  of the body portion  12 . The tip portion  14 , between the body portion  12  and the inlet opening  20 , tapers in diameter along a concave curve  26 . In some embodiments, the concave curve  26  does not extend entirely to the inlet opening  20  as the inlet diameter  22  extends axially from the inlet opening  20  to the concave curve  26 . It shall be understood that the curve  26  may be straight or a profile that is aerodynamically suitable in one embodiment. 
     As shown, the tip portion  14  has a tip length L. The length of the tip may be limited by an ability of a heating element or coils disposed inside the tip to provide heat to it. That is, if the tip is too long, the heater may not be able to heat a distal end thereof such that ice does not form or otherwise accumulate in or on the tip  14 . 
     Referring now to  FIG. 2 , the pitot tube  10  includes a tube passage  28  extending along an interior of the pitot tube  10  from the inlet opening  20  to a tube end  30 . The tube passage  28  is bounded along its length by a tube inner surface  32  that is offset a distance from a tube outer surface  34 . Together, the tube outer surface  34  and the tube inner surface  32  define a tube wall  36  having a tube wall thickness  38 . In some embodiments, the tube wall thickness  38  is uniform along a tube length, while in other embodiment the tube wall thickness  38  may vary along the tube length. As illustrated, a heating element  40  is disposed within the tube passage  28 . The type and configuration of this heating element  40  may include coils or any other type of heating element. In one embodiment, the heating element  40  includes one or more coil wraps disposed at the tube passage  28 , the one or more coil wraps establishing a variable watt density along the interior of the pitot tube  10 . 
     One or more thermally conductive inserts  42  are located in the tube wall  36 , radially between the tube inner surface  32  and the tube outer surface  34 . The inserts  42  are utilized to improve heat transfer rates and performance from the heating element  40  throughout the pitot tube  10 . As shown in  FIG. 2 , inserts  42  may be placed along the body portion  12  as well as at the tip portion  14 . Referring now to  FIG. 3 , in some embodiments the inserts  42  are rectilinear in shape, and further may include one or more through openings  44  extending in a heat transfer direction through the insert  42 , such as radially outwardly when the insert  42  is in an installed position in the pitot tube  10 . The insert  42  is formed from a material having a higher thermal conductivity than a base material of the pitot tube  10 . In some embodiments, the insert  42  is formed from, for example, annealed pyrolytic graphite (APG), graphite, or other high thermal conductivity materials such as copper. Typically, the base material of the pitot tube  10  is a nickel alloy or copper alloy material, such as beryllium copper. 
     Referring now to  FIG. 4 , in some embodiments the insert  42  includes a base insert portion  46  formed from, for example the APG or graphite material or other highly thermally conductive material, and a coating portion  48  encapsulating or covering the base insert portion  46 . The coating portion  48  is a chromium or nickel material, and may be applied to the base insert portion  46  by, for example, a plating process or other coating process. As shown in  FIG. 5 , in embodiments of inserts  42  with through openings  44  in the base portion  46 , the coating portion  48  may fill the through openings  44 . In other embodiments, the through openings  44  are filled with metal material during direct energy metal deposition manufacturing of the inserts  42 . The through openings  44  are provided to improve through plane thermal conductivity of the inserts  42 , due to relatively lower through-plane conductivity of the APG inserts  42 . In some embodiments, such as when inserts  42  are formed from metal materials, through openings  44  may not be necessary, since metals have isotropic thermal conductivity. 
     While the description above relates to pitot tubes  10 , the present disclosure may be readily applied to other air data probes and sensors, such as a total air temperature (TAT) probe  50 , shown in  FIGS. 6 and 7 . The TAT probe  50  includes a probe housing  52 , which may include one or more inserts  42  embedded in the probe housing  52 . 
     Referring now to  FIG. 8 , a method of making an air data probe, such as a pitot tube  10  or a TAT probe  50  is illustrated. In block  100 , one or more inserts  42  are formed from, for example, APG. In some embodiments, at block  102  the one or more inserts  42  are plated or coated with, for example, chromium or nickel materials to improve bonding to the pitot tube  10  and prevent oxidation of the insert  42 . At block  104 , a direct energy metal deposition process, such as laser metal deposition, is performed under inert atmosphere to encapsulate the one or more inserts  42  into a pitot tube  10  having a near-net shape. In block  106 , heat treatment or another process, such as hot isostatic pressing (HIP), is performed on the near-net shape pitot tube  10 . Finally, at block  108  one or more machining operations are performed on the pitot tube  10  to finalize the shape of the pitot tube  10 . 
     The sensors disclosed herein, including the inserts  42 , improves heat transfer of the sensors to prevent and/or alleviate icing conditions at the sensor. Further, forming the sensor via direct energy metal deposition allows the inserts to be readily embedded into the sensors, and the coating of the inserts  42  improves adhesion of the base metal to the inserts  42 , and also prevents oxidation of the inserts  42 . 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.