Measuring equipment comprising a heating device

Abstract

The invention relates to measuring equipment comprising a heating device, the equipment being intended to be externally arranged on the skin of a vehicle capable of travelling in a climatic environment susceptible to icing conditions, the equipment corresponding to a body formed of a shaft carrying a tube that is closed at one of its ends, the heating device being intended to be housed within the tube and comprising at least one heating wire wound inside the body of the tube, the winding being a bridged winding defined by the presence of a bridge (P), the bridge corresponding to a portion of the heating wire that overlaps, along the axis of the tube, a predetermined number of turns of the end of the winding located close to the open end (12) of the tube, the overlapping turns being regularly spaced apart according to a predetermined pitch associated with the overlapping region.

Description

[0001] TITLE: Measuring equipment including a heating device

[0002] The present invention relates to measuring equipment comprising a heating device, said measuring equipment being intended to be arranged outside and at the skin of a vehicle capable of moving in a hostile climatic environment associated with icing climatic conditions, said equipment corresponding to a body formed of a mat carrying a tube closed at one of its ends, the heating device being intended to be housed within said tube and comprising at least one heating wire wound in the body of said tube

[0003] The invention also relates to an aircraft comprising such measuring equipment.

[0004] The invention relates to the field of heating measuring equipment intended to be arranged at the skin of a vehicle capable of moving in a hostile climatic environment associated with icing climatic conditions, and in particular supercooled water icing climatic conditions or crystal icing climatic conditions.

[0005] Such equipment corresponds, for example, to civil or military aeronautical measuring equipment comprising flush parts or appendages protruding from the skin of the aircraft (i.e. located outside the aircraft). According to another example, such equipment is ground-based measuring equipment for military, scientific or even meteorological fields, in particular for measurements in a context of extreme polar cold.

[0006] These appendages or these flush parts belong, for example, to probes making it possible in particular to measure different aerodynamic parameters of the air flow surrounding the aircraft, such as in particular the total pressure, the static pressure, the temperature, or the incidence of the air flow in the vicinity of the skin of the aircraft. The total pressure makes it possible, combined with the static pressure, to determine the local speed of the air flow in the vicinity of the probe, and ultimately the air speed of the aircraft carrying said probe, as well as the altitude.

[0007] Other probes, for example, can measure the local incidence of an air flow. Incidence probes can include movable appendages designed to orient themselves along the axis of the air flow surrounding the probe. The orientation of the probe can determine the incidence of the air flow. Other incidence probes can be equipped with fixed appendages equipped with several pressure taps. The pressure difference measured between these pressure taps can also determine the incidence of the air flow surrounding the probe.

[0008] When flying at high altitude, the aircraft may encounter icing conditions.

[0009] More specifically, frost can form on the aircraft's skin and appendages. The appearance of frost is particularly problematic for aerodynamic probes, whose profiles can be modified by frost and whose pressure tapping holes can be obstructed. In other words, the presence of frost can distort the probe's total pressure measurement and possibly render it inoperable in certain climatic conditions.

[0010] One solution to prevent frost buildup is to heat the appendages. Currently, heating is usually achieved using one or more heating wires wound and embedded in the appendages, with heating occurring through the Joule effect. For example, to heat a total pressure probe, several hundred watts of power must be dissipated.

[0011] More precisely, this type of probe is formed of a mast carrying a tube closed at one of its ends and called a Pitot tube, or this type of probe is a Pitot-static probe.

[0012] The heating of the probe is carried out by means of one or more heating wires, forming a heating resistance, wound (i.e. shaped in the form of a coil) in the body of the probe, that is to say both in the mast and in the Pitot tube 10, the Pitot tube being illustrated by FIG. 1. Such a Pitot tube 10 has at an open end 12 allowing in particular the measurement of the total atmospheric pressure. In addition, according to one embodiment, such a tube optionally has an internal tube 14, located inside the Total tube 16. Between these two tubes 14 and 16, a space 18 is intended for the insertion of the heating wire.

[0013] To produce the heating wire, an electrical conductor (i.e. core) comprising an alloy of iron and nickel coated with an electrical but not thermal mineral insulator such as alumina or magnesia is commonly used. The insulator is itself coated with a sheath of nickel, nickel chromium, or inconel allowing the wire to be brazed to the body of the probe. In other words, such a heating wire corresponds to a metal-sheathed coaxial cable, or as an alternative to a shielded spiral wire. The shaping of the heating wire, also referred to subsequently by the term "winding", within the Pitot tube 10, with or without an internal tube 12, is complex and aims to provide a significant heat density regularly distributed along the wall of the tube 10 (of very small size, compared to the possibilities of forming the wire), and especially as close as possible to its open end 12, the most critical for anti-icing and de-icing, particularly in supercooled water.

[0014] In other words, the way in which this heating element, generally of the metal-sheathed coaxial heating wire type, is shaped (i.e. "coiled") in the tube 10 of the Pitot or Pitot static pressure probe impacts the defrosting capabilities, particularly defrosting in supercooled water.

[0015] Current heating wire shaping solutions are illustrated by figures 2 and 3, respectively representative on the one hand of a pinned winding of the state of the art, and on the other hand of a round-trip winding as disclosed in patent EP 3 173 797 B1.

[0016] Figure 2 illustrates a pinned winding based on the use of a pin 20 positioned along the radial axis of the inner tube 14 of Figure 1, the inner tube 14 being not shown in Figure 2 for the sake of simplification. To form a pinned winding, the heating wire is first bent at mid-length to make a loop 22, the loop 22 then being hooked to the pin 20. Then, the “double wire” corresponding to the two branches of the loop 22 is simply wound, in a single thickness, over a predetermined length with a predetermined pitch on the inner tube 14 of Figure 1 and a winding template, the winding (i.e. the winding) being carried out in a forward direction opposite the open end 12 of the Pitot tube towards the rear of the probe.

[0017] However, the pinned winding is not optimal mainly due to the loop 22 which surrounds the pin 20, the diameter of this loop 22 requiring the second turn 24 of double wire of the heating wire coil to be moved back. This offset generates empty spaces 26 between the turns of the heating wires, due to the initial forming loop 22, the surface area of ​​these empty spaces 26 being too large in proportion to the directly heated surface. The density of heating wire is therefore lower than on the rest of the winding while it is precisely at the open end 12 of the probe that the most power must be provided. This technological limitation is today compensated by ensuring that the complete winding has enough power to transfer it forward by thermal conduction, but the disadvantage is overheating of the nose of the Pitot tube on the ground or in non-icing conditions.Furthermore, such voids 26 are potentially conducive to corrosion because they are likely to fill with pollution from the environment of the vehicle on which the measuring equipment comprising said tube 10 is placed.

[0018] As an alternative, Figure 3 represents another solution of the state of the art corresponding to round-trip winding as disclosed in patent EP 3 173 797 B1. Such round-trip winding consists of winding the heating wire in a single (and not in a double-wire as for the pinned winding previously described in relation to Figure 2) wire on a template, then the internal tube 14 (not shown in Figure 3 for the purposes of simplification) in a first “forward” direction from the rear to the front 12 of the probe. Then, once arrived at the open end 12, the winding is continued in the same direction of rotation but by winding over the initial winding (i.e. coaxially) in a second “return” direction from the front 12 towards the rear of the probe, opposite in direction (i.e. reverse direction) to the first “forward” direction from the rear towards the front 12 of the probe.

[0019] In other words, such a "back and forth" winding necessarily results in a superposition of two layers 28 and 30 (thicknesses) of winding, as illustrated in section under the broken line of Figure 3, which reduces the efficiency of the heating wire for transmitting heat by conduction. Indeed, between the two thicknesses of wire, a central heat accumulation zone is formed, because the wire is not in direct contact with the heat exchange zones, so that such a winding is likely to disadvantageously cause, under predetermined conditions, a temperature rise above or very close to the melting point of the solder which holds the wire assembled on the body of the probe, and consequently potentially a reduction in the lifetime of the probe.

[0020] In the non-joining part of the double winding (i.e. in two superimposed layers), the two thicknesses 28 and 30 do not overlap over the entire surface. However, it is difficult to ensure that the inner winding 30, smaller in diameter, is well pressed against the walls and dissipates the heat well. Thus, this solution, although effective locally at the open end 12 of the tube 10, is not very effective in terms of overall efficiency and also leads to an increased risk of overheating on the ground.

[0021] In summary, such a “round trip” winding of Figure 3 proposes to reduce the empty spaces 26 of the pinned winding, by a “double winding” corresponding to a coaxial superposition of the wound wire, but thus creating an “overdensity” of heat which can be detrimental to the life of the heating wire, and what is more, by not allowing the power necessary for defrosting to be optimized, by creating zones without direct heat exchange with the zones to be heated.

[0022] Another prior art solution, not shown, is to use a portion of a non-self-regulating bi-material heating wire on the first turns of the winding at the nose of the Pitot tube, to avoid losing local heating capacity when the conditions at the nose are severe, the resistance of the wire decreasing with temperature in more conventional structures. However, the use of a bi-material heating wire is expensive and presents reliability risks, in particular due to a potential breakage of the wire at the junction of the two materials constituting it.

[0023] The aim of the present invention is therefore to overcome the drawbacks of the aforementioned state of the art, by proposing a new solution for shaping the heating wire (i.e. a new type of winding) in order to integrate an optimal length of wire into the limited space offered by the tube 10, and this by seeking to position the greatest density of heating wire towards the front of the measuring equipment, i.e. close to the open end 12 of the tube, to ensure that maximum heat is provided to the nose of the measuring equipment, the nose being the part most exposed to hostile external climatic conditions, such as freezing climatic conditions supercooled water or freezing climatic conditions crystals.

[0024] For this purpose, the subject of the invention is a measuring equipment comprising a heating device, said measuring equipment being intended to be arranged outside and at the skin of a vehicle capable of moving in a hostile climatic environment associated with icing climatic conditions, said equipment corresponding to a body formed of a mat carrying a tube closed at one of its ends, the heating device being intended to be housed within said tube and comprising at least one heating wire wound in the body of said tube, the winding of said heating wire is a back-and-forth bridged winding defined by the presence of a bridge, the bridge corresponding to a portion of heating wire overlapping, along the axis of said tube, a predetermined number of turns of the end of said winding located near the open end of said tube,said overlapped turns being regularly spaced according to a predetermined pitch associated with the overlapping zone.,

[0025] Such a "bridged winding" proposed according to the present invention makes it possible to increase the heating density at the front open end of the tube, which is the critical area for anti-icing or de-icing the probe in supercooled water icing conditions, but also to a lesser extent in crystal icing conditions.

[0026] In other words, the principle of the present invention therefore consists of removing the pin and the initial forming loop of the pinned winding in order to be able to arrange the winding turns in a regularly spaced manner, while carrying out the return path of the wire parallel to the axis of revolution of the winding and in a heat exchange zone with the zones to be heated in order to limit superpositions and therefore heat losses.

[0027] The bridge of the bridged winding according to the present invention makes it possible to obtain a “round trip” winding that is almost single-thick and not double-thick according to the aforementioned state of the art relating to round trip winding as disclosed in patent EP 3 173 797 B1. Indeed, the only double-thickness zone according to the present invention is limited to the overlap zone and has a surface limited to the contact surface between the bridge wire and the turns that the bridge overlaps (i.e. spans), so that the heat generation associated with this reduced contact surface is negligible in terms of heat loss.

[0028] According to other advantageous aspects of the invention, the measuring equipment comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0029] - according to a first configuration, said bridge is external, being located on the overlapped turns in a radial direction going from the inside to the outside of said tube;

[0030] - according to a second configuration, said bridge is internal, being located under the overlapped turns, in a radial direction going from the inside to the outside of said tube;

[0031] - each turn forming the winding is wound in the same direction with a winding diameter that is substantially equal from one turn to the next;

[0032] - said predetermined number of turns and / or the spacing pitch of said turns is predetermined as a function of the heat density required to defrost the open end of said tube, and according to a predetermined vehicle mission;

[0033] - said turns overlapped by said bridge are joined;

[0034] - said equipment has within said tube a groove configured to house said bridge;

[0035] - said measuring equipment is a Pitot probe or a Pitot-static probe, said tube corresponding to a Pitot tube, said groove being provided at the level of the tube of the Total of said Pitot tube to accommodate an external bridge according to said first configuration;

[0036] - said measuring equipment is a Pitot probe or a Pitot-static probe, said tube corresponding to a Pitot tube, said Pitot tube further comprising an internal tube, said groove being provided at said internal tube of said Pitot tube to accommodate an internal bridge according to said second configuration.

[0037] The invention also relates to an aircraft comprising measuring equipment comprising a heating device as described previously.

[0038] These characteristics and advantages of the invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which:

[0039] [Fig 1] Figure 1 is a schematic sectional view of measuring equipment according to the present invention corresponding to a Pitot type pressure probe; [Fig 2] [Fig 3] Figures 2 and 3 illustrate the state-of-the-art solutions described previously for heating the measuring equipment of Figure 1, and not re-described subsequently;

[0040] [Fig 4] Figure 4 is a schematic view of two embodiments of a bridged winding proposed according to the present invention.

[0041] In the remainder of the description, the expression “substantially equal to” defines a relationship of equality to plus or minus 10%, preferably to plus or minus 5%.

[0042] Subsequently, by “turn” is meant each of the turns of the heating wire from which the winding according to the present invention is formed.

[0043] Figure 4 is a schematic view of two embodiments 32 and 34 of a bridged winding of a heating device of a measuring equipment, proposed according to the present invention, and intended to be arranged outside and at the skin of a vehicle capable of moving in a hostile climatic environment associated with icing climatic conditions, said equipment corresponding to a body formed of a mast carrying a tube 10, as illustrated in Figure 1 previously described, said tube 10 being closed at one of its ends.

[0044] The heating device is intended to be housed within said tube 10 and comprises at least one heating wire wound in the body of said tube 10.

[0045] More precisely, for these two embodiments (i.e. configurations) 32 and 34, the winding of said heating wire is a back-and-forth bridged winding defined by the presence of a bridge P, the bridge P corresponding to a portion of heating wire overlapping, along the axis 36 of said tube, a predetermined number of turns of the end of said winding located near the open end 12 of said tube 10, said overlapped turns being regularly spaced according to a predetermined pitch associated with the overlapping zone.

[0046] It should also be noted that each end of the bridge is used to form a coil.

[0047] According to a complementary optional aspect, the predetermined number of worst overlaps is strictly less than the total number of turns minus one. According to another complementary optional aspect, advantageously, in terms of space requirement, thermal because limiting the hot spots and maximizing the contact areas between heating wire and tube 10, for these two embodiments (i.e. configurations) 32 and 34, each turn forming the winding is wound in the same direction (i.e. preferably from the front 12 to the rear or alternatively from the rear to the front 12) with a winding diameter D substantially equal from one turn to the other.In addition, the predetermined number of turns and / or the spacing pitch of said turns, for example four turns for the first configuration 32, and seven turns for the second configuration 34, is predetermined as a function of the heat density required to defrost the open end 12 of said tube 10, and according to a predetermined mission of the vehicle, in particular taking into account for example the geographical area of ​​the mission and the associated climate, but also the type of measuring equipment considered. According to another example, said overlapped turns are joined over the first centimeter of winding near the open end 12, and there are ten joined turns in number.

[0048] The predetermined number of turns and / or the spacing pitch of said turns is in particular obtained by means of thermal calculations as a function of the heating density (i.e. heat) required near the open end 12 and for the measurement mission considered, to prevent any measurement from being distorted by icing.

[0049] According to an alternative embodiment, the spacing pitch is such that said turns overlapped by said bridge are contiguous, which makes it possible to maximize the heating density near the open end 12 of the tube 10, the most critical area to be defrosted, in particular to prevent the frost from distorting the measurement carried out by means of said measuring equipment. For example, said overlapped turns are contiguous over the first centimeter of winding near the open end 12.

[0050] According to a first configuration 32, said bridge P is external by being located on the turns, adjoining in the example of figure 4, in a radial direction going from the inside to the outside of said tube 10 (i.e. the term “external” being understood in said radial direction going from the inside to the outside of said tube 10).

[0051] To obtain such shaping of the first configuration 32 illustrated by FIG. 4, the associated shaping method comprises a first step of forming the contiguous part of the heating wire turns, then a second step of forming the external point P above said contiguous turns, then a third step of shaping the non-contiguous part of the heating wire.

[0052] According to an additional optional variant, when, as illustrated by FIG. 1, the measuring equipment is a Pitot probe or a Pitot-static probe, such equipment has within the tube 10 a groove configured to house said bridge P. It should be noted that in FIG. 4, for reasons of representation, the groove suitable for housing the external bridge of the first configuration 32 is not shown whereas it would be provided in the tube of the T otale 16 of FIG. 1 to house the external bridge P according to said first configuration 32. According to a second configuration 34, said bridge P is internal by being located under the turns, contiguous in the example of FIG. 4, in a radial direction going from the inside to the outside of said tube 10 (i.e. the term "internal" being understood in said radial direction going from the inside to the outside of said tube 10).

[0053] According to an additional optional variant, when, as illustrated by Figure 1, the measuring equipment is a Pitot probe or a Pitot-static probe, said tube 10 corresponding to a Pitot tube, said Pitot tube further comprising an internal tube 14 as illustrated in Figures 1 and 4, such equipment has within the tube 10, and at said internal tube 14, a groove 38 configured to house said bridge P. To obtain such a shaping of the second configuration 34 illustrated by Figure 4, the associated shaping method comprises a first step of preforming the internal bridge P, a second step of inserting said internal bridge P into said dedicated groove 38 of the internal tube 14, then a third step of forming the contiguous part of the heating wire turns, as illustrated according to the example of Figure 4, then a fourth step of forming the non-contiguous part of the heating wire turns.

[0054] Regardless of the configuration 32 or 34, the bridged winding comprises, according to the embodiment illustrated by FIG. 4, both a non-joining part and a joining part overlapped by said bridge.

[0055] Regardless of the configuration 32 or 34, according to an aspect not shown, the holding in position of these assemblies is carried out by strong brazing, all of the cavities and intersections of the part being filled with brazing.

[0056] It should be noted that such heating assemblies with bridged windings benefit in particular from the evolution of the parts around the winding. Indeed, in the latest probe designs, such parts, namely the internal tubes 14 and Totale tubes 16 tend to be increasingly thicker, and the present invention takes advantage of this extra thickness of material to accommodate other functions, such as the bridged winding proposed here, the housing grooves optionally proposed in addition to accommodate the winding bridge P being suitable for being integrated (i.e. accommodated) within such an extra thickness of the internal tube 14 for the configuration 34 of bridged winding with internal bridge, and of the Totale tube 16 for the configuration 32 of bridged winding with external bridge.

[0057] This bridge allows, regardless of the 32 or 34 configuration, to obtain a “Back and Forth” winding almost in “single thickness” of heating wire.

[0058] The very thin “double thickness” surface is certainly likely to generate a thermal loss, but negligible, especially considering the fact that embedding the bridge P in a groove 38 of the internal tube 14 or of the Total 16 (i.e. external tube 16) makes it possible to recover the calories from this portion of the heating wire bridge for heating the areas to be defrosted.

[0059] It should be noted that the end winding may or may not have a joined turn, depending on the heat density required in this area.

[0060] Those skilled in the art will understand that the invention is not limited to the embodiments described, nor to the particular examples of the description, the embodiments and variants mentioned above being suitable for being combined with each other to generate new embodiments of the invention.

[0061] Thus, the present invention, by the proposed bridged winding, and illustrated by figure 4, makes it possible to retain all the advantages of the "round trip" winding of the state of the art illustrated previously by figure 3, while avoiding the bulk and loss of efficiency associated with the implementation of a double thickness over the entire "round trip" of the winding. In other words, the present invention makes it possible to do away with the double thickness which takes up more space and which leads to difficulties in heat dissipation.

[0062] More specifically, the bridged winding proposed according to the present invention makes it possible to bring the greatest possible density of heating wire to the front of the measuring equipment, and this without the empty spaces associated according to the state of the art with a pinned winding.

[0063] The present invention makes it possible in particular to significantly improve the de-icing performance of Pitot or Pitot-static probes in supercooled water, particularly in the most critical zone: the front end of such Pitot or Pitot-static probes, without however impacting the life of the wire by overheating in less severe conditions, particularly on the ground or in the case of high altitude dry air flight.

Claims

DEMANDS 1. Measuring equipment comprising a heating device, said measuring equipment being intended to be placed outside and at skin level on a vehicle designed to travel in a hostile climatic environment associated with icing climatic conditions, said equipment corresponding to a body formed of a mast carrying a tube (10) closed at one of its ends, the heating device being intended to be housed within said tube (10) and comprising at least one heating wire wound in the body of said tube, characterized in that the winding of said heating wire is a bridged winding defined by the presence of a bridge (P), the bridge (P) corresponding to a portion of heating wire overlapping, along the axis (36) of said tube, a predetermined number of turns of the end of said winding located near the open end (12) of said tube (10),said overlapping spirals being regularly spaced according to a predetermined pitch associated with the overlap zone.

2. Measuring equipment according to claim 1, wherein, according to a first configuration (32), said bridge (P) is external by being located on the overlapping turns in a radial direction going from the inside to the outside of said tube (10).

3. Measuring equipment according to claim 1, wherein, according to a second configuration (34), said bridge (P) is internal by being located under the overlapping turns, in a radial direction going from the inside to the outside of said tube (10).

4. Measuring equipment according to any one of the preceding claims, wherein each turn forming the winding is wound in the same direction with a winding diameter (D) substantially equal from one turn to another.

5. Measuring equipment according to any one of the preceding claims, wherein said predetermined number of turns and / or the pitch of spacing of said turns is predetermined as a function of the heat density required to defrost the open end (12) of said tube (10), and according to a predetermined vehicle mission.

6. Measuring equipment according to claim 5, wherein said coils overlapped by said bridge are contiguous.

7. Measuring equipment according to any one of the preceding claims, wherein said equipment has within said tube (10) a groove (38) configured to house said bridge.

8. Measuring equipment according to claims 2 and 7, wherein said measuring equipment is a Pitot probe or a static Pitot probe, said tube (10) corresponding to a Pitot tube, said groove being provided in the Total tube (16) of said Pitot tube (10) to house an external bridge according to said first configuration (32).

9. Measuring equipment according to claims 3 and 7, wherein said measuring equipment is a Pitot probe or a static Pitot probe, said tube (10) corresponding to a Pitot tube, said Pitot tube further comprising an inner tube (14), said groove being provided at the level of said inner tube (14) of said Pitot tube (10) to house an internal bridge according to said second configuration (34).

10. Aircraft comprising measuring equipment including a heating device according to any one of claims 1 to 9.

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