Aeronautical measuring instrument and associated manufacturing method

Abstract

The present invention relates to an aeronautical measuring instrument (10) comprising a body (22) and a heating element (40), the body (22) defining a region of interest (25) intended to be exposed to aerodynamic flows. The instrument (10) is characterized in that the heating element (40) is encapsulated in the body (22) and configured to heat the region of interest (25).

Description

[0001] TITLE: Aeronautical measuring instrument and associated manufacturing process

[0002] The present invention relates to an aeronautical measuring instrument.

[0003] The present invention also relates to a manufacturing method associated with such an instrument.

[0004] The field of the invention is that of aeronautical measuring instruments such as aerodynamic measuring probes. These instruments are subject to icing conditions when mounted on an aircraft or on a wind turbine, for example.

[0005] To perform its mission, an aircraft includes several measuring instruments comprising parts that are flush with the surface or appendages that protrude from the skin of the aircraft.

[0006] These appendages or protruding parts belong, for example, to probes used to measure various aerodynamic parameters of the airflow surrounding the aircraft, such as total pressure, static pressure, temperature, slippage, or the angle of incidence of the airflow in the vicinity of the aircraft skin.

[0007] The aircraft may encounter difficult environmental conditions such as frost or standing water.

[0008] More specifically, frost can form on the aircraft's skin and appendages. Frost formation is particularly problematic for measuring instruments, such as aerodynamic probes, whose profiles can be altered by frost and whose pressure ports can be obstructed. Nacelle-mounted measuring instruments can also be affected by frost.

[0009] Several solutions are already known in the state of the art to overcome this problem.

[0010] For example, document FR 2833347 describes an aerodynamic measuring probe whose heating is achieved by means of electrical resistors extending into the appendages. Heating is accomplished by the Joule effect and is specifically achieved using a heating element in the form of a heating wire wound within the probe body, that is, both in the mast and in the Pitot tube of the probe. To manufacture the heating wire, an electrical conductor consisting of an iron-nickel alloy coated with a mineral insulator such as alumina or magnesia is used. However, this solution has limitations; manufacturing the heating wire and assembling it (soldering) within the probe require a series of complex and costly operations. The energy consumption of the wire also remains very high.

[0011] Other technologies for heating an aerodynamic measurement probe are considered in document US 4275603.

[0012] This document describes the use of a heat pipe that delivers thermal energy around the tube. The return of the heat transfer fluid to a liquid state is ensured through a porous material. This allows the probe to be positioned in any possible orientation on the aircraft skin.

[0013] In practice, this solution offers no industrial advantage due to the difficulty of inserting a porous material into a probe. It also necessitates design modifications. The manufacturing process for such a probe is at least as complex as that using a heating wire.

[0014] The present invention aims to solve problems in the prior art and to provide an aeronautical measuring instrument with efficient heating means. Furthermore, this measuring instrument can be manufactured in a particularly simple and inexpensive manner.

[0015] For this purpose, the invention relates to an aeronautical measuring instrument comprising a body and a heating element, the body defining an area of ​​interest intended to be exposed to aerodynamic flows.

[0016] The heating element is encapsulated in the body and configured to heat the area of ​​interest.

[0017] According to other advantageous aspects of the invention, the measuring instrument comprises one or more of the following features, taken individually or in all technically possible combinations:

[0018] - the heating element extends through one or more cavities formed in the body;

[0019] - where each cavity is filled with an electrically insulating filling material;

[0020] - the filling material includes at least one of the following:

[0021] - a resin;

[0022] - a silicone;

[0023] - an epoxy;

[0024] - a polyurethane; - the heating element comprises a heating wire including a conductive core; - the heating wire further comprises an insulator and / or a sheath;

[0025] - the heating element includes a conductive ink disposed at least partially on a support;

[0026] - the heating element is capable of emitting heat by Joule effect through the circulation of electric current;

[0027] - the instrument forming an aerodynamic measuring probe.

[0028] The invention also relates to a method for manufacturing an instrument as defined above, comprising encapsulating the heating element in the body.

[0029] According to other advantageous aspects of the invention, the method includes the following feature:

[0030] - The encapsulation of the heating element includes the following steps:

[0031] - formation of one or more cavities in the body;

[0032] - insertion of the heating element into the cavity or each cavity;

[0033] - filling the cavity or cavities with a filling material. The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawing in which:

[0034] [Fig. 1] Figure 1 is a schematic cross-sectional view of an aeronautical measuring instrument according to the invention.

[0035] Figure 1 illustrates an aeronautical measuring instrument 10 according to the invention. This instrument 10 can be used in any environment exposed to aerodynamic flows.

[0036] In particular, the instrument 10 according to the invention allows the measurement of at least one of the physical values ​​relating to the medium, such as total pressure, static pressure, incidence, temperature, speed, etc.

[0037] More particularly, according to one embodiment, the measuring instrument 10 is an aerodynamic measuring probe, for example an anemobaroclinometric probe which can for example measure several of the aforementioned quantities.

[0038] The environment in which the measuring instrument 10 is at least partially exposed is in particular a freezing environment, that is to say an environment in which frost accretions are likely to form outside or inside the measuring instrument 10.

[0039] The measuring instrument 10 is advantageously mounted on the fuselage of an aircraft or on the external part of a wind turbine. An aircraft is defined as any pilotable machine capable of moving through the air. In particular, an aircraft may be an airplane, a helicopter, or a drone.

[0040] As illustrated in Figure 1, the measuring instrument 10 comprises an internal part 12 to the aircraft fuselage whose external surface is the surface 20, a base 14 and a measuring element 16.

[0041] The base 14 allows the instrument 10 to be fixed on an external surface which is exposed to aerodynamic flows.

[0042] In particular, the base 14 can be fixed to a surface of the aircraft fuselage or to an external surface of the wind turbine such as a blade.

[0043] This surface is designated under reference 20 in Figure 1. In some examples, the base 14 may include a plate extending along the surface 20 and allowing the base 14 to be fixed to the surface 20.

[0044] The base 14 is fixed to the internal part 12 of the fuselage.

[0045] The measuring element 16 extends from the base 14.

[0046] In the example shown in Figure 1, the measuring element 16 is free to rotate relative to the outer surface 20 and forms, for example, a weather vane. According to other embodiments, the measuring element 16 has a static element relative to the outer surface 20 and is formed, for example, by a mast and a Pitot tube supporting the mast.

[0047] The internal part 12 of the fuselage also extends from the base 14 but in the opposite direction to that of the measuring element 16.

[0048] In particular, the internal part 12 of the fuselage includes, for example, a housing designed to be received in a recess formed, for example, in the surface 20 or, more commonly, in a free space behind the aircraft fuselage, the external part of which is the surface 20. This housing includes a sensitive part capable of generating a measurement signal following, for example, a movement of the measuring element 16, and a transmitter for transmitting the measurement signals to an external system. The internal part 12 of the fuselage also includes a control module 21 for controlling the operation of at least some components of the measuring instrument 10.

[0049] In the following description, the base 14 and the measuring element 16 will be considered to form a body 22 of the instrument 10. This body 22 may be made of one or more pieces of material. The piece or pieces are made, for example, of a metal.

[0050] In particular, the body 22 is intended to be exposed to the outside of the object on which the measuring instrument 10 is mounted. In other words, the body 22 is exposed to aerodynamic flows. The body 22 defines at least one area of ​​interest 25 in which the formation of frost must be prevented when the body 22 is exposed to aerodynamic flows. In some embodiments, the body 22 defines several distinct areas of interest 25.

[0051] Depending on the nature of the measuring instrument 10, the area of ​​interest 25 can extend over an internal and / or external surface of the body 22.

[0052] In the example in Figure 1, the area of ​​interest 25 extends over an outer surface of the wind vane, for example along its leading edge, and over at least part of the outer surface of the base 14. In other words, in this case, the area of ​​interest 25 may have a plurality of distinct sub-areas that may overlap. In the case of a measuring probe including a Pitot tube, an area of ​​interest may extend over an inner and / or outer surface of this Pitot tube and, in some cases, over a part of the inner and / or outer surface of the mast supporting the Pitot tube.

[0053] According to the invention, the measuring instrument 10 further comprises a heating element encapsulated within the body 22 so as to heat the area of ​​interest. Optionally, a heating element 40 is encapsulated near the area or areas of interest 25 or each corresponding sub-area. Without loss of generality, only the case of a single heating element 40 and a single area of ​​interest 25 will be described hereafter.

[0054] The heating element 40 is advantageously electrically resistive. It produces heat by Joule heating, that is, when an electric current passes through it. The operation of the heating element 40 is controlled, for example, by the control module 21. In particular, the control module 21 allows the heating element 40 to be powered by an electric current from, for example, an external source.

[0055] In various embodiments, the heating element 40 comprises or consists of an electrical wire and / or conductive ink. For example, the heating element 40 may consist solely of the heating wire, solely of the conductive ink, or a combination of the heating wire and the conductive ink. The heating element 40 can be connected to cold leads by integrating the solder into the encapsulation.

[0056] In some embodiments, the heating element 40 comprises graphene or is made of graphene.

[0057] The heating wire includes, in particular, a core. This core is made at least partially of an electrically conductive material such as a metal.

[0058] In some embodiments, the heating wire has only a core. In such cases, this wire is electrically insulated from the body 22 by a filling material described in detail below. According to other embodiments, the heating wire also includes insulation and a sheath surrounding the core. In some embodiments, the heating wire is impregnated so that the impregnation forms electrical insulation. In some embodiments, a heat-shrinkable sheath is used.

[0059] Conductive ink can be applied partially or entirely to a substrate. This substrate is made, for example, of an electrically insulating material such as polyimide, epoxy, mica, Nomex, etc. The conductive ink can be of the PTC (Positive Temperature Coefficient) or NTC (Negative Temperature Coefficient) type. It can also be a resistive ink or any other type of ink that allows for the heating of parts.

[0060] Advantageously, the heating element 40 extends through one or more cavities 45 formed in the body 22, advantageously near the area of ​​interest 25. In the example in Figure 1, a single cavity 45 is formed in the body 22. This cavity 45 is, for example, formed in the inner part of the body 22 and opens into the base 14. In the example in Figure 1, the cavity 45 has a parallelepiped shape in cross-section. In other examples, the cavity 45 may have a more complex shape, for example, a shape chosen according to the shape of the heating element 40 and / or the body 22.

[0061] Generally, the cavity or cavities 45 can be formed inside the body 22 and / or on an exterior and / or interior surface of this body 22. In the first case, the cavity or cavities 45 are covered and have at least one open end for the insertion of the heating element 40. In the other two cases, the cavity or cavities 45 are partially open. In other words, in these two cases, the cavity or cavities 45 are partially delimited by the corresponding surface of the body 22.

[0062] Advantageously, the cavity or each cavity 45 is formed by extrusion or machining of the part or each piece forming the body 22. According to another example, the cavity or each cavity 45 as well as the part or each piece forming the body 22 are formed by an additive manufacturing technique such as 3D printing.

[0063] Furthermore, the cavity or each cavity 45 is filled with a filling material, advantageously electrically insulating.

[0064] Preferably, the filler material includes at least one of the following:

[0065] - a resin;

[0066] - a silicone;

[0067] - an epoxy;

[0068] - a polyurethane. Furthermore, and advantageously, the filling material exhibits high thermal conductivity. This thermal conductivity is, for example, between 0.01 and 300 W / m². 1 K' 1 .

[0069] Finally, the filling material has properties that allow it to withstand the corresponding environmental conditions (i.e. humidity, temperature, etc.) as well as the heating temperature of the heating element 40.

[0070] A manufacturing process for the measuring instrument 10 will now be explained. In an initial step, one or more cavities 45 are formed in one or more parts intended to form the body 22. These cavities 45 are formed, in particular, using one of the aforementioned techniques.

[0071] Next, the heating element 40 is inserted into the cavity or cavities 45. The insertion method depends in particular on the nature of the heating element 40 and the type of cavity 45 (open, closed, semi-open, etc.). Specifically, when a cavity 45 has only one or two open ends, the heating element 40, for example, which may have a heating wire, can be inserted through one of these ends. It should also be noted that the dimensions of the heating element 40 are slightly smaller than those of the corresponding cavity 45 to facilitate its insertion.

[0072] Next, the filler material is injected into the cavity or cavities 45 to secure the heating element 40 inside it and, if necessary, to electrically insulate it from the body 22. This injection is controlled to completely fill the corresponding cavity while minimizing porosity in the filler material. This control depends on numerous parameters (viscosity, mixing, vacuum injection, temperature, resin injection point, degassing, polymerization, etc.).

[0073] In addition, the injection can be done via the use of a syringe directly into the corresponding cavity 45 or any other method facilitating filling such as making an injection hole in the body 22.

[0074] The heating element 40 is thus encapsulated in the body 22 near the area of ​​interest 25.

[0075] Finally, the other elements are assembled to form the measuring instrument 10 as described above.

[0076] It is therefore understandable that the present invention offers several advantages. First, the invention provides a heating solution that is easier to integrate into measuring instruments and less expensive than other heating solutions known to date. Furthermore, the invention facilitates the integration of cold leads. Indeed, to date, the usual techniques used to secure a heating element to a measuring instrument are based on brazing. The main drawback is the use of flux, which must be cleaned to prevent premature corrosion of the wire. The brazing residue must also be manually polished, resulting in a substantial additional cost. The encapsulation of the heating element according to the invention does not present these disadvantages.

Claims

DEMANDS 1. Aeronautical measuring instrument (10) comprising a body (22) and a heating element (40), the body (22) defining an area of ​​interest (25) intended to be exposed to aerodynamic flows; the instrument (10) being characterized in that: - the heating element (40) is encapsulated in the body (22) and configured to heat the area of ​​interest (25); - the heating element (40) extends through one or more cavities (45) formed in the body (22); - the cavity or each cavity (45) is filled with an electrically insulating filling material; and - the filling material includes at least one of the following: - a resin; - a silicone; - a polyurethane.

2. Instrument (10) according to any one of the preceding claims, wherein the heating element (40) comprises a heating wire including a conductive core.

3. Instrument (10) according to claim 2, wherein the heating wire further comprises an insulator and / or a sheath.

4. Instrument (10) according to any one of the preceding claims, wherein the heating element (40) comprises a conductive ink disposed at least partially on a support.

5. Instrument (10) according to any one of the preceding claims, wherein the heating element (40) is capable of emitting heat by Joule effect through the circulation of electric current.

6. Instrument (10) according to any one of the preceding claims, forming an aerodynamic measuring probe.

7. Instrument (10) according to any one of the preceding claims, wherein the heating element (40) comprises graphene or is made of graphene.

8. Method of manufacturing an instrument (10) according to any one of the preceding claims, comprising encapsulating the heating element (40) in the body (22).

9. A method according to claim 8, wherein the encapsulation of the heating element (40) comprises the following steps: - formation of one or more cavities (45) in the body (22); - insertion of the heating element (40) into the cavity or each cavity (45); - filling of the cavity or each cavity (45) with a filling material.

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