tubular radiator

Abstract

Tubular heating elements (100, 300, 400, 500) with an at least partially freely coiled electric heating element (111, 202, 311, 411, 511) which is arranged at least partially in the interior of a tubular metal sheath (110, 310, 410, 510) and is electrically insulated from it by an electrically insulating material, wherein the tubular heating element (100, 200, 300, 400, 500) has at least a first section (a) in which a shaped body (114, 201, 210, 220, 314, 414, 514) made of an electrically insulating material surrounds a freely coiled section of the at least partially freely coiled electric heating element (111, 202, 311, 411, 511) so that it is insulated from the tubular metal sheath (110,310,410,510) is insulated and has at least two second sections (b) in which the electrical heating element (111,202,311,411,511) is at least partially freely coiled in an electrically insulating powder (115,315,415,515) or granules embedded and thereby insulated from the tubular metal sheath (110, 310, 410, 510) and wherein the shaped bodies (114, 201, 210, 220, 314, 414, 514) made of electrically insulating material are fixed to the at least partially freely coiled electrical heating element (111, 202, 311, 411, 511), characterized in that spacer and / or positioning elements are arranged between the shaped bodies (114, 201, 210, 220, 314, 414, 514) made of electrically insulating material, which determine the distance between adjacent shaped bodies (114, 201, 210, 220, 314, 414, 514) made of electrically insulating material and / or the position of the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material in the tubular heating element (100,300,400,500), , and / or that the fixed shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material are fixed with a flexible, knotable and / or windable element (207), and / or that the fixed shaped bodies (114,201,201,220, 314,414,514) are mechanically locked by inserting a T- or L-shaped mechanical locking element (208) into the interior of the coils of the electric heating element (202), by inserting a ceramic pin (212) between coils of the electric heating element (202) in a locking manner, or by deforming a section of the heating wire coil (202).

Description

[0001] Tubular heaters are electrical heating devices in which one or more electrical heating elements are arranged, at least in sections, freely coiled in the interior of a tubular metal casing and are electrically insulated from this by an electrically insulating, preferably highly thermally conductive material.

[0002] Such tubular heaters are known, for example, from US 1 494 937 A, US 2 499 961 A, and US 3 614 387 A. In particular, the first-mentioned document discloses a tubular heater having the features of the preamble of patent claim 1.

[0003] Despite this seemingly simple design, significant problems arise in the manufacture of such tubular heaters. These problems are primarily due to the fact that in many cases the diameter or the largest dimension within the tube cross-section of the tube forming the tubular metal casing is just a few millimeters, while the typical length of the tubular metal casing during manufacture can be several meters, so that the cross-section to length ratio is in the order of 1:1000. This means that the electric heating element must be positioned with an angular accuracy of better than 0.1°. Currently, attempts are being made to achieve this precision using filling towers, in which gravity assists in the alignment of the electric heating element and the tubular metal casing; however, these are very expensive.

[0004] The object of the invention is therefore to provide a tubular heater that can be manufactured with less effort. This object is achieved by a tubular heater having the features of patent claim 1. Advantageous developments of the invention are the subject of the dependent claims.

[0005] The tubular heater according to the invention comprises at least one electrical heating element, which is at least partially freely coiled and arranged at least partially within the interior of a tubular metal casing and is electrically insulated therefrom by an electrically insulating material. Of course, multiple electrical heating elements can also be optionally provided, or at least one electrical heating element can be U-shaped, so that both ends of the electrical heating element are located at the same end of the tubular heater.

[0006] What is essential to the invention is that the tubular heating element has at least a first section in which a shaped body made of an electrically insulating material surrounds a freely coiled section of the electrical heating element (and thus not applied to a support structure such as a winding body) so that it is insulated from the tubular metal casing, and has at least two second sections in which the electrical heating element is embedded in an electrically insulating powder or granulate and is thus insulated from the tubular metal casing. These second sections are in particular sections adjacent to the first section. The electrically insulating powder or granulate can in particular be a magnesium oxide powder or granulate; the electrical heating element is preferably formed by a resistance wire or heating wire.

[0007] In the first sections, a freely coiled section of the electric heating element is thus enclosed by the molded body made of electrically insulating material. The molded body made of electrically insulating material thus has an opening through which the freely coiled section of the electric heating element extends. This opening is preferably dimensioned such that its cross-section is adapted to the cross-section of a coil in this coiled section of the electric heating element, so that the opening guides the section of the electric heating element passing through it, at least in places or sections.

[0008] By means of the shaped bodies made of electrically insulating material, which surround and guide the electrical heating element in sections, a noticeable increase in positioning accuracy can be achieved, while at the same time the electrical heating element is supported or braced by the shaped bodies made of electrically insulating material in such a way that a filling tower can be dispensed with, because even in an inclined position the shaped bodies made of electrically insulating material prevent the electrical heating element from sagging in an arc shape under its own weight.

[0009] According to a preferred embodiment of the invention, the shaped bodies made of electrically insulating material are threaded onto the electrical heating element.

[0010] In the tubular heater according to the invention, the position of the shaped bodies in the tubular heater is well defined because the shaped bodies made of electrically insulating material are fixed to the electrical heating element.

[0011] An inventive alternative for achieving this goal is that spacer and / or positioning elements are arranged between the shaped bodies made of electrically insulating material, which specify the distance between adjacent shaped bodies made of electrically insulating material and / or the position of the shaped bodies made of electrically insulating material in the tubular heater. Furthermore, such spacer and / or positioning elements can increase the rigidity of the structure comprising the electric heating element and shaped bodies made of electrically insulating material and thus contribute to enabling more precise manufacture of the tubular heater in a position deviating from the vertical or to increasing precision. The shaped bodies made of electrically insulating material can also be fixed to the spacer and / or positioning elements.

[0012] According to another alternative of the invention, a flexible knottable and / or windable element, e.g. a ceramic yarn, is used to fix the shaped bodies made of electrically insulating material. In particular, such a flexible knottable and / or windable element can also be bound in such a way that it is also guided along the electrical heating element between the fixing points of adjacent shaped bodies made of electrically insulating material. This then makes it possible to specify the maximum distance between these fixing points by the length of the flexible knottable and / or windable element. This is of great interest, in particular when using very thin resistance wires in coiled sections, even during vertical production using a filling tower, since this can reduce unwanted elongation of these sections and the associated change in the coil spacing under the influence of gravity.

[0013] It is preferred if the electrical heating element is centered at least by sections of the outer contour of the shaped bodies made of electrically insulating material within the tubular metal casing.

[0014] According to a particularly preferred embodiment of the invention, the molded bodies made of electrically insulating material consist of two or more parts and are arranged around the electrical heating element or threaded onto the electrical heating element by connecting the parts to one another or to the electrical heating element. This allows for particularly rapid arrangement of the molded bodies made of electrically insulating material on the electrical heating element.

[0015] It is further preferred if at least one thermocouple or one sensor element is arranged inside the tubular metal casing, the connecting lines of which are centered by the shaped bodies made of electrically insulating material.

[0016] For many applications, it is useful for the tubular heater to have connecting wires that make electrical contact with the electric heating element. This contact can be located, in particular, within the tubular metal casing.

[0017] It is particularly advantageous if the molded bodies are made of electrically insulating material and / or the electrically insulating powder or granules are impregnated, as this achieves improved resistance to moisture. Silicone preparations are particularly suitable for this purpose.

[0018] Silicates or magnesium oxide are particularly preferred as materials for the molded bodies made of electrically insulating material.

[0019] Particularly preferably, the tubular heating element is completely or partially compacted, which in particular results in improved heat conduction

[0020] In a preferred embodiment of the invention, the molded bodies made of electrically insulating material have a passage opening for the inflow of the electrically insulating powder or granules to facilitate filling the interior of the tubular metal casing. The passage openings can also be realized as recesses on the edge, particularly in the form of locations or sections where the outer contour of the molded body does not rest against the tubular metal casing.

[0021] The unclaimed method for producing such a tubular heater comprises the steps - Providing a tubular metal casing, - Providing an electrical heating element which is at least partially coiled, - arranging shaped bodies made of electrically insulating material on the electric heating element so that the shaped bodies made of electrically insulating material surround sections of the electric heating element, - Inserting the electric heating element with the molded body made of electrically insulating material arranged thereon into the tubular metal casing, and - Filling the remaining volume inside the tubular metal casing with electrically insulating powder or granules The order of the first two steps is not important and the arrangement of shaped bodies can take place after, but not necessarily immediately after, the provision of the electrical heating element.

[0022] The invention is explained in more detail below with reference to figures illustrating exemplary embodiments. They show: Fig. 1a: A partially opened view of an embodiment of a tubular heater, Fig. 1b: a first enlarged section from Fig. 1a, Fig. 1c: a second enlarged section from Fig. 1a, Fig. 1d: a longitudinal cross-section through the tubular heater made of Fig. 1a, Fig. 2a: a first possibility for attaching a shaped body to the electric heating element, Fig. 2b: a second possibility for attaching a shaped body to the electric heating element, Fig. 2c: a third possibility for attaching a shaped body to the electric heating element, Fig. 2d: a fourth possibility for attaching a shaped body to the electric heating element, Fig. 2e: a fifth possibility for attaching a shaped body to the electric heating element, Fig. 2f: a sixth possibility for attaching a shaped body to the electric heating element, Fig. 2g: a seventh possibility for attaching a shaped body to the electric heating element, Fig. 2h: an eighth possibility for attaching a molded body to the electric heating element, Fig. 2i: a ninth possibility for attaching a shaped body to the electric heating element, Fig. 2j: a tenth possibility for attaching a shaped body to the electric heating element, Fig. 2k: an eleventh possibility for attaching a molded body to the electric heating element, Fig. 21: a twelfth possibility for attaching a shaped body to the electric heating element, Fig. 2m: a thirteenth possibility for attaching a shaped body to the electric heating element, Fig. 3a: a longitudinal section through a second embodiment of a tubular heater, Fig. 3b: a cross-section through the tubular heater from Fig. 3a, Fig. 4a: a longitudinal section through a third embodiment of a tubular heater, Fig. 4b: a cross-section through the tubular heater from Fig. 4a, Fig. 5a: a longitudinal section through a fourth embodiment of a tubular heater, and Fig. 5b: a cross-section through the tubular heater from Fig. 5a.

[0023] Fig. 1a shows a partially opened tubular heater 100 with a tubular metal casing 110 and an electrical heating element 111 designed as a freely coiled resistance wire arranged in the interior of the tubular metal casing 110, the ends of which are connected to connecting wires 112, 113 for electrically contacting the electrical heating element 111, which lead out of the tubular metal casing 110 on one end face at a time. Shaped bodies 114 made of an electrically insulating material are arranged in places around the electrical heating element 111 so that they define the position of the electrical heating element 111 relative to the inner surface of the tubular metal casing 110. The remaining volume within the tubular metal casing 110, shown in white, is filled with an electrically insulating, preferably highly thermally conductive powder 115, e.g., magnesium oxide powder.

[0024] As can be seen particularly clearly in the enlarged sections of the Fig. 1b, Fig. 1c and in the cross-sectional view 1d, the tubular heating element 100 thus has first sections a, in which a shaped body 114 made of an electrically insulating material surrounds a freely coiled section of the electrical heating element 111 so that it is insulated from the tubular metal casing 110, and second sections b, in which the electrical heating element 111 is embedded in the electrically insulating powder 115 and is thereby insulated from the tubular metal casing 110.

[0025] Since it is very difficult to guide the electric heating element 111 through the shaped bodies 114 when these are already located inside the tubular metal casing 110, the shaped bodies 114 should be arranged on or at the electric heating element 111, whereby according to the invention, a fixing of the shaped body 114 is carried out. A variety of such fixing options are presented below, as is the case with the Fig. 1d, the arrangement of a shaped body 114 on the electric heating element 111, marked with a dashed circle, can be realized in concrete terms.

[0026] In the unclaimed solution according to Fig. In Figure 2a, a substantially hollow-cylindrical shaped body 201 is pushed onto a freely coiled electric heating element 202, with its position being predetermined by the presence of a larger coil 203 on one side, which mechanically prevents the shaped body 201 from slipping in this direction. The shaped bodies 201 are sequentially threaded onto the electric heating element 202, brought to the respective desired position, and then the coil 203 is enlarged by bending it upwards.

[0027] As in Fig. As can be seen in Figure 2b, this unclaimed concept can also be modified in such a way that the hollow cylindrical shaped body 201 pushed onto the freely coiled electric heating element 202 is stabilized in its position on both sides by larger coils 203,204.

[0028] Further unclaimed variants of the fixing of a hollow cylindrical shaped body 201 pushed onto the electric heating element 202 can be found in particular in the Fig. 2c and Fig. 2d, where the fixing is carried out by ceramic adhesive or cement joints 205,206 on one or both sides.

[0029] Variants of such a fixation according to the invention are shown in Fig. 2e and Fig. 2f. In the Fig. 2e, the fixation is achieved by tying the shaped body 201 to the electric heating element 202 with a flexible, knottable and / or twistable element 207, such as a yarn, thread, rope, or ribbon, which is preferably not electrically conductive and which is made in particular of a ceramic material, asbestos, quartz, or glass fiber. For this purpose, the flexible, knottable and / or twistable element 207 can be knotted into turns of the electric heating element 202 and wound around the shaped body 201.

[0030] In connection with the last-discussed variant, it should also be pointed out that the flexible, knottable and / or windable element 207 can be continued following a fixing node arranged behind a first shaped body 201, also to the next node arranged in front of the next shaped body 201, so that it connects adjacent shaped bodies 201 to one another and thus defines a maximum distance between these shaped bodies 201.

[0031] In the variant according to the invention Fig. 2f, a T- or L-shaped mechanical locking element 208 is inserted into the interior of the coils of the electrical heating element 202.

[0032] If one decides on a molded body 210 made of electrically insulating material, which is somewhat more complex to manufacture and has a bore 211 that completely or partially passes through the molded body 210 in the radial direction, further fixing options according to the invention arise. Thus, as shown in the sequence of figures of the Fig. 2g, a ceramic pin 212 is passed between coils of the electric heating element 202 or, as shown in Fig. 2h, inserted between coils of the electric heating element 202 and optionally secured with an adhesive or cementing point 213 using ceramic adhesive or cement. If necessary, such a fixation can also be achieved, as shown in Fig. 2i, the electric heating element 202 can be deformed such that at the engagement point of the ceramic pin 212 the coil spacing between the coils of the electric heating element between which the ceramic pin 212 engages is increased.

[0033] Yet another procedure according to the invention for fixing a shaped body 210 with bore 211 is shown in the Fig. 2j, in which the bore is used to deform the section of the heating wire coil 202 running in the region of the bore 211 by temporarily inserting a punch 213 after threading and arranging at the desired position of the shaped body 210 in such a way that it dips into the bore 211 and thus mechanically blocks any displacement of the shaped body 210.

[0034] The molded bodies 220 of the embodiments illustrated in Figure sequences 2k, 2l and 2m are even more complex in design, consisting of two molded body parts 220a, 220b that can be connected to one another to form the molded body 220. This additional effort for the molded body 220 is compensated, however, by the fact that it is not necessary to thread it onto the electrical heating element 202, but rather it can be assembled at the desired location. The molded body parts 220a, 220b have projections 221 that either, as illustrated in Figure sequence 2k, engage between adjacent coils of the electrical heating element 202 or, as shown in Figure sequence 21, between which a section of the electrical heating element 202 with a reduced coil diameter lies, or between which a non-coiled section of the electrical heating element 202 lies, which in Fig. 2m is shown.

[0035] The basic structure of the Fig. 3a,b; Fig. 4a,b und Fig. The tubular heaters 300, 400 and 500 shown in Figures 5a, b are highly similar to those of tubular heater 100. They each have a tubular metal casing 310, 410, 510 and an electrical heating element 311, 411, 511 designed as a freely coiled resistance wire, arranged in the interior of the tubular metal casing 310, 410, 510, the ends of which are connected to connecting wires 312, 313, 412, 413, 512, 513 for electrically contacting the electrical heating element 311, 411, 511, which are led out of the tubular metal casing 310, 410, 510 on one side at the end. In this case, shaped bodies 314, 414, 514 made of an electrically insulating material are arranged in places around the electrical heating element 311, 411, 511, so that they define the position of the electrical heating element 311, 411, 511 relative to the inner surface of the tubular metal jacket 310, 410, 510.The remaining volume shown in white within the tubular metal jacket 310,410,510 is filled with an electrically insulating, preferably highly thermally conductive powder 315,415,515, e.g. magnesium oxide powder.

[0036] The main difference between tubular heaters 300, 400, 500 and tubular heater 100 from the Fig.1a to 1d is that the former have support structures 320, 420, 520 in which the shaped bodies 314, 414, 514 are mounted. In the tubular heater 300, the support structure 320 is a flat plate with recesses into which arms 314a of the shaped bodies 314 engage. In the tubular heater 400, the support structure 420 is formed by two such plates, and in the tubular heater 500, the support structure 520 is angled. In this way, a preconfigured internal structure can be provided in each case, which is inserted into the tubular metal casing 310, 410, 510 and can be joined together, e.g., by pressing, after its remaining interior space has been filled with the electrically insulating powder 315, 415, 515. List of reference symbols 100,300,400,500 tubular radiators 110,310,410,510 tubular metal jacket 111,311,411,511 electric heating element 112,113,312,313, 412,413,512,513 connecting wire 114,314,414,514 molded bodies 115,315,415,515 electrically insulating powder 201,210,220 molded bodies 202 electric heating element 203,204 larger helix 205,206,213 Adhesive or putty joint 207 flexible knottable and / or windable element 208 locking element 211 bore 212 ceramic pen 213 stamps 220a molded body part 220b molded body part 221 lead 320,420,520 support structure a first section b second section

Claims

[1] Tubular heating element (100, 300, 400, 500) with an at least partially freely coiled electrical heating element (111, 202, 311, 411, 511), which is arranged at least partially in the interior of a tubular metal casing (110, 310, 410, 510) and is electrically insulated therefrom by an electrically insulating material, wherein the tubular heating element (100, 200, 300, 400, 500) has at least a first section (a), in which a shaped body (114, 201, 210, 220, 314, 414, 514) made of an electrically insulating material surrounds a freely coiled section of the at least partially freely coiled electrical heating element (111, 202, 311, 411, 511), so that it is surrounded by the tubular metal casing (110,310,410,510) and has at least two second sections (b) in which the at least partially freely coiled electrical heating element (111,202,311,411,511) is embedded in an electrically insulating powder (115,315,415,515) or granulate and is thereby insulated from the tubular metal casing (110,310,410,510) and wherein the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material are fixed to the at least partially freely coiled electrical heating element (111,202,311, 411,511), , characterized by that between the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material, spacer and / or positioning elements are arranged, which specify the distance between adjacent shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material and / or the position of the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material in the tubular heating element (100,300,400,500), and / or that the fixed shaped bodies (114, 201, 210, 220, 314, 414, 514) made of electrically insulating material are fixed with a flexible, knottable and / or windable element (207), and / or that the fixed shaped bodies (114, 201, 201, 220, 314, 414, 514) are mechanically locked by inserting a T- or L-shaped mechanical locking element (208) into the interior of the coils of the electrical heating element (202), by lockingly inserting a ceramic pin (212) between coils of the electrical heating element (202) or by deforming a section of the heating wire coil (202). [2] Tubular heating element (100,300,400,500) according to claim 1, characterized by that the shaped body (114,201,210,220,314,414,514) made of electrically insulating material is threaded onto the electrical heating element (111,202, 311,411,511) which is freely coiled at least in sections. [3] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized bythat the at least partially freely coiled electrical heating element (111,202,311,411,511) is centered at least by sections of the outer contour of the shaped bodies (114,201,210,220,314, 414,514) made of electrically insulating material within the tubular metal casing (110,310,410,510). [4] Tubular heating element (100, 300, 400, 500) according to one of the preceding claims, characterized by that the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material consist of two or more than two parts and are arranged around the at least partially freely coiled electrical heating element (111,202,311,411,511) or are threaded onto the at least partially freely coiled electrical heating element (111,202,311,411,511). [5] Tubular heating element (100, 300, 400, 500) according to one of the preceding claims, characterized by that at least one thermocouple or one sensor element is arranged inside the tubular metal casing (110,310,410,510), the connecting lines of which are centered by the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material. [6] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized by that the tubular heating element (100,300,400,500) has connecting wires (112,113, 312,313,412,413,512,513) with which the at least partially freely coiled electrical heating element (111,202,311,411,511) is electrically contacted. [7] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized by that the shaped bodies (114,201,210,220,314,414,514) are made of electrically insulating material and / or the electrically insulating powder (115,315,415,515) or granules are impregnated. [8] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized bythat the shaped bodies (114,201,210,220,314,414,514) consist of electrically insulating material made of a silicate or of magnesium oxide. [9] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized by that the tubular heater (100,300,400,500) is compressed. [10] Tubular heating element (100,300,400,500) according to one of the preceding claims, characterized by that the shaped bodies (114,201,210,220,314,414,514) made of electrically insulating material have a passage opening for trickling in the electrically insulating powder (115,315,415,515) or granules.

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