DE2203642A1 - Electric heating devices and methods for their manufacture - Google Patents

Description

The invention relates to electrical heating devices and devices of the type in which an electrical heating element is arranged in a groove in a thermally conductive component or member is formed (incorporated, inserted).

An electric heater of the type set forth above is for use in de-icing the Wings and other parts of aircraft have been proposed. The suggestion sees pasting or inserting an electrically insulated heating

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elements in a groove provided or molded into a metal block that is incorporated into the structure of the relevant and important aircraft part is incorporated or used. The heating element will held at the bottom of the groove, namely with the help of pins or other pegs, rods or the like, and then aluminum is deposited on the block along the length of the groove so that the Groove above the heating element is filled (closed).

The aluminum is deposited with the help of

". _JT - TO.1- -χ. (Metal spraying). Flame or arc spraying 'completed, and it is necessary, after completion of the spraying, to remove the parts of the precipitate which (and where) they extend (protrude) over and outside the groove (burr removal, flushing ), so that the original block profile is restored,

The previously proposed electric heater is subject to the disadvantage that each Defect (e.g. blowholes, holes or the like) of the metal deposit in the groove - such imperfections can be due to the presence of grease, for example or other foreign matter can easily arise on the heating element during its installation - to one Overheating of the element leads to this (flaw) point. Such overheating can easily lead to it lead to the fact that the entire heating element fails, i.e. completely fails. In addition, there is the disadvantage that one is compelled to use flame-spraying of metal, and one must also use the following grinding or burr removal or the like. Accept a considerable part of the precipitate formed or provision.

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An object of the invention is to provide a shape and type of electric heater of the aforesaid Kind along with a process for their manufacture to create which essentially Extensive avoids the disadvantages of the previously known design.

In accordance with a feature of the present invention, an electric heater is said type characterized in that the heating element in the groove in thermal contact or thermal contact with good heat transfer with the mentioned link or block, namely by contraction (narrowing or constriction, contraction) of the groove mouth (groove opening).

In accordance with another feature of the invention, there is a method of making an electrical Heating device of the type mentioned in that a force or forces are applied or applied along the groove which deform said member (block) and / or the heating element, so that as a result such a deformation the heating element in thermal contact (contact that promotes heat transfer) held with said member or block by constriction or contraction of the groove mouth will.

The contracting (pressing together, narrowing, constricting) of the groove mouth can, in the new method, ren by deforming the mentioned member or block

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inwardly across the groove mouth along one, but preferably along both flanks or sides of the groove achieved or provided after the heating element has been inserted therein (into the groove). Alternatively, the groove can be formed (from the beginning) with an (already) constricted mouth, so that work with it from the beginning, and in this case the heating element can be squeezed into the groove, to fill this groove under the mouth.

An electric heater, manufactured according to the present invention and built into a wing of an aircraft for de-icing purposes, will now be described as an example of a possible embodiment of the invention with reference to the drawing . In the drawing show:

Figure 1 shows a cross section of the wing nose

of the aircraft with built-in electrical heating device _/

FIG. 2 shows a partial section of the wing leading edge (nose) of the aircraft wing, according to arrow II in FIG. 1, the section in FIG. 1 corresponding to line II in FIG.

Figure 3 is a partial section of an electrical connector j which represents part of the electrical heating unit of Figures 1 and 2,

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Figures 4a, 4b and 4c consecutive

Phases of the manufacture of the electrical heating device according to FIGS Figures 1 and 2, and

Figures 5a, 5b and 5c in succession

different phases an alterna-. tive manufacturing method of electrical Heating device of Figures 1 and 2.

Referring to Figures 1 and 2, the device or unit comprises an elongated block (member) 10 made of aluminum, corrosion-resistant (stainless) steel or titanium, and this block extends along the leading edge (leading edge) of the wing of the aircraft. The block 10 is built in or mounted within the metal skin 11 of the wing} and, since it has a contour that conforms or precisely corresponds to the inner surface of the skin 11 along the wing nose or leading edge, it is held precisely fitting in the wing nose, and has good, intimate contact, and therefore there is thermal contact (that is, good thermal conductivity, that is, very good heat transfer) with or to and from the skin 11 over its full length.

A mineral (eg ceramic or similar material) insulated electrical cable 12 is present and forms a heating element for deicing the wing nose of the aircraft, and it is embedded in the surface of the block 10 immediately below the skin 11. The cable 12 has an internal

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_τ .. / en resistance heating wire). τβη Lexter (core, T_ $ i which is contained in external sheath Ik (made of copper, made of stainless steel, made of titanium, or nickel or the like) and is electrically insulated from it, e.g. by powdered material 15 (made of magnesium oxide, made of zirconium or alumina, alumina, zirconia or the like), which is compactly and tightly filled into the jacket 14. The supply of electrical current to the cable 12 is effected by means of supply cables 16 which are separated from each other with the ends of the cable 12 by means of Connecting pieces 17 are connected, the latter 17 being embedded in the block 10 in the vicinity (under) the skin 11.

The cable 12 is held under the skin 11 in a groove 18 which is cut, milled or otherwise molded into the contoured (curved in cross-section) surface of the block 10. The groove 19 contains the cable 12 and extends between the embedded connectors 17 along a serpentine of "pinched" S-shape having three spaced apart and parallel sections each of which extends across spanning almost the length of the block. The cable 12 ^u xs £ shaped so that it has a larger cross-sectional area in its curved (bent) areas than in its straight and parallel sections in the groove l8 (it is connected or coupled to the connections 17); in this way it is possible to limit the heat losses per unit length in these sections.

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All connecting pieces 17 are, as shown in Figure 3, in an individual cavity 19 used in block 10. The middle conductor 13 (core) of the cable 12 is stripped in the cavity (bare) and is inserted into one end of a bare metal sleeve 20 · The stripped (bare) inner Conductor 21 of the feed cable 16 is inserted into the sleeve 20 from the other end, and good electrical Interconnection with the conductor 13 is made by undulating deformation (zigzag pressing, multiple beads) or soldering the two ends in or with the sleeve 20 concerned. Electrical isolation of these Interconnection, along with sealing the ends of cables 12 and 16, is accomplished by a filling 22 made of glass or epoxy resin (ethoxylin resin or the like) within the entry or of the cavity 19 causes.

The cable 12 extends along its serpentine path between the two connections 17 » and it is held in the groove 18 with the aid of a narrowing or closing of the groove mouth. this is accomplished during the manufacture of the unit in the manner shown in FIG.

According to Figure 4 (Fig. 4a, b and c) are the Groove l8 and the cable 12 at the beginning, as shown at (a), of rectangular (or in this case more precisely: ■ square) cross-section. The cable 12 fits quite precisely into the groove l8. After it has been introduced, a Pressure on the surface of the block (link) 10 on both sides of the groove 18 by two press and roll rollers 23

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practiced and applied, as shown at (b). The rollers are vigorously on the surface of the Blocks 10 (Fig. 4b from left to right) pressed, and then they are rolled along the groove 18 (if necessary. rolled back and forth) to produce indentations in Fig. 24 as shown at (c), so so that these deforming impressions 24 produce or have lateral material deviations that then accordingly by deforming the block surface inwards over the groove (in the groove mouth) of both Pages arise and close the groove in the mouth area more or less. This deformation, too like the narrowing of the groove mouth, serves to grasp or enclose and pest hold the cable 12, it squeezes the e.g. permanently deformable sheath 14 of the cable 12 so that a very tight, well-contacting Fitting and seating is assured and therefore there is good thermal contact, i.e. a good heat transfer between the cable 12 and the block 10 within the entire facility *

As an alternative to the manufacturing method shown in FIG. 4, the manufacturing method according to FIG 5 can be applied. In this alternative method there is a groove 18 * with a dovetail cross section (So from the beginning provided with a narrower mouth) provided in block 10, as in (a) of FIG. 5. The cable 12 'used in this method has an elongated rectangular shape Cross-sectional area, and if it is inserted 12 * into the groove l8, then it protrudes like at (b) shown in FIG. 5, somewhat or substantially above

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the block surface addition (Fig. 5 protruding beyond the surface to the left). The one specified at (b) Pressure is now applied to the protruding cable 12 * with the aid of a roller 25. The roller 25 is "moved along the length of the groove l8 '(backwards and process), and by means of pressure (see Arrow in Fig. 5b) then the roller 25 presses the cable 12 * into the groove so that the groove fills, and this achieves a good thermal contact (good heat transfer) with or in the block 10, as shown in (c) of FIG.

The heating device described as an example comprises a single heating element; However, this said Example not that several heating elements cannot be used. For example, parallel Sections or the parallel sections of the single cable may alternatively be used or applied be, for example, by separate cable lengths; these .. = heating cables can be mutually connected be with appropriate supply cables, which can also be separate. Multiple arrangement in different So arrangement is possible.

- 10 claims

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Claims (1)

- 10 -. January 25, 1972 EXPECTATIONS Electrical heating device in which an electrical heating element is arranged in a groove which is present in a thermally conductive member (block), characterized in that the heating element (12) in the groove (l8) in thermal contact (heat-conducting contact) with the block (1O) by constriction or compression of the groove mouth held is. 2. Electrical heating device according to claim 1, characterized in that the heating element is a cable which is insulated by mineral substances or a mineral substance and has an outer (deformable) metal jacket (lk) . A method for producing an electrical heating device, in which an electrical heating element is inserted into a groove formed in a thermally conductive member · (block) or is present, characterized in that a or »or more · force · are applied in such a way that the «· XrIfti or di ·» · force d «« limb 'block) 10 (partially) deformed and / or that there * Hei * - • l «n« nt (12) is thereby deformed, * o that 209834/1057 59Wl5 / Bu / gn - 11 - 25 January 1972 as a result of this deformation, the heating element is in thermal contact, d _f h. is held and embedded in good intimate contact with the limb (block), namely by contraction or other narrowing or closing of the groove mouth, 4. The method according to claim 3i characterized in that g e k e η η · shows that the member (10) is deformed inwardly over the groove mouth, transversely to the groove mouth that is, along one or both planks of the groove (l8) after the heating element (12) in the groove was made 5 · The method according to claim 3 »characterized in that the groove (l8) (from the start) is or is provided with a narrowed mouth, and that then the heating element (12) in this groove is squeezed in so that it fills this groove behind or under the groove mouth. 6. The method according to one or more of claims 3 to 5, characterized in that a mineral-insulated cable (12) is used as the heating element, which has a metal jacket (Ik) of rectangular cross-section. 209834/1057