Abstract:
An electrical heating element with a metal jacket, a connecting element lying against the metal jacket at least in some sections and at least one electrical connection. The connecting element has at least one cavity, which borders on a section of the metal jacket at least in some sections and/or on a section of the electrical connection, and the cavity is cast at least partly with a pourable sealing compound, especially with a ceramic cement, epoxy resin or plastic, such that a direct, supporting mechanical connection is consequently produced between the metal jacket and the connecting element and/or between the section of the electrical connection and the connecting element by the pourable sealing compound, wherein the pourable sealing compound is also in contact with an element for securing against rotation, and a process for the manufacture of such an electrical heating element.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2010 009 180.4 filed Feb. 24, 2010, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention pertains to an electrical heating element and a process for manufacturing such an electrical heating element. Such heating elements are used for heating tools, machine parts and devices or media used in same. 
       BACKGROUND OF THE INVENTION 
       [0003]    Basically, in all these applications, the question arises as to how the respective electrical heating element used can be fastened to the respective device. A connecting element, for example, a flange, threaded nipple, angle, fitting, a disk or another suitable turned, punched or cast part, is usually provided for this. 
         [0004]    At the same time, this connecting element is usually the point, at which a force and/or a torque are exerted, when a heating element which was already used shall be removed, for example, when replacing the heating element. It has been shown in practice that, after long use, heating elements often sit very rigidly in their mount because of deposits on the heating element, so that they have to be loosened or detached before the actual removal by applying a considerable torque to the connecting element. This results in the need to prepare a connection between connecting element and heating element, which is not twisted against its original position even when a considerable torque is applied, since, with insufficient torsional strength, the heating element can no longer be loosened in its mount and thus can no longer be removed from there. 
         [0005]    The connecting element is therefore usually pressed, welded or soldered on in order to be able to withstand such stresses. These work steps lead to considerable costs in the manufacture of the electrical heating element. 
         [0006]    As an alternative, it is known, e.g., from DE 203 08 941 U1 to inject prepared plastic parts on the heating element by injection molding, which can then be used as a connection element. However, because of the high tool costs associated therewith, this is also an expensive process, which may be profitable for mass production at the most. 
         [0007]    Furthermore, it is unfavorable in all these processes that in such attached connecting elements, a considerable thermal or mechanical stress is always exerted on the heating element, with which routinely undesired damage is brought about to installed sensors, securing elements and switches as well as to stranded wire insulation and/or pourable sealing compound and thus the reject rate is increased. Further, an impairment to a possible surface treatment of the heating element, e.g., due to tempering colors and/or other thermal or mechanical damage, as it is experienced, for example, by an electropolished surface in the above-mentioned methods, routinely occurs in this manner of attaching the connecting element to the heating element. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, the object of the present invention is to provide an electrical heating element with a connecting element arranged on it, which can be manufactured in an especially favorable manner and especially cost-effectively and whose connecting element is connected in such a way to the electrical connecting element that a good securing against rotation is achieved. In addition, damage to the heating element by means of mechanical and thermal stress or a possible structural change in the connecting element during welding shall be largely avoided. 
         [0009]    This object is accomplished by an electrical heating element of the present invention and a process for manufacturing such an electrical heating element of the present invention. 
         [0010]    The electrical heating element according to the present invention has a metal jacket, a connecting element lying on the metal jacket at least in some sections and at least one electrical connection. According to the present invention, the connecting element has at least one cavity, which borders, at least in some sections, on one section of the metal jacket, for example its front side, and/or on a section of the electrical connection. Furthermore, the cavity is cast at least partly with a pourable sealing compound, especially with a ceramic cement, epoxy resin or plastic, such that a direct, supporting mechanical connection is consequently produced between the metal jacket and the connecting element and/or between the section of the electrical connection and the connecting element by the pourable sealing compound. 
         [0011]    Thus, the pourable sealing compound is used here not only as a means for securing a differently produced mechanical connection between connecting element and electrical heating element, and especially with regard to sealing and electrical insulation, but also represents this mechanical connection directly. This permits a very cost-effective manufacture. 
         [0012]    Not absolutely the shortest connection is intended with the term “direct connection” in this regard. A direct connection in terms of this patent application is present if there is a path between metal jacket and connecting element or section of the electrical connection and connecting element that leads completely through pourable sealing compound. 
         [0013]    Furthermore, it is made explicitly clear that the connecting element may be multisectional, e.g., when a ring or spacer is pushed onto the heating element, then the part of the connecting element, which makes possible the fastening, e.g., by means of its thread, is pushed onto this, and then is cast with pourable sealing compound. 
         [0014]    The thermal stress during casting with pourable sealing compound is markedly less than the stress occurring during welding, soldering or injection molding; a mechanical stress as when pressing on the connecting element does not develop. Therefore, the manner of connection according to the present invention is especially suitable for avoiding damage to installed sensors, securing elements and switches as well as to stranded wire insulation and/or pourable sealing compound. At the same time, it is a cost-effective solution, especially also since the operation of welding, soldering or pressing is entirely omitted. 
         [0015]    To guarantee that the connection using the pourable sealing compound has the needed securing against rotation, a means for securing against rotation is, moreover, provided according to the present invention, with which the pourable sealing compound is in contact. 
         [0016]    The electrical heating element may be, for example, a heating cartridge, a tubular heating body, or a screw-in heating body. 
         [0017]    The connecting element lying on the metal jacket in at least some sections may be, for example, a flange, a threaded nipple, an angle, a fitting, a disk or another suitable turned, punched or cast part. 
         [0018]    On an end-side section of the metal jacket within the metal jacket, the heating device according to the present invention has at least one cavity, which passes over into at least one cavity of the connecting element. A cavity is also basically defined here as an opening passing through the connecting element. 
         [0019]    The core idea of the present invention is that these cavities are cast at least partly with a pourable sealing compound, for example, with epoxy resin or a plastic, and a compact connection is consequently produced between the metal jacket and the connecting element, wherein the needed torsional strength is guaranteed by the provision of a means for securing against rotation. 
         [0020]    In a preferred embodiment of the present invention, the means for securing against rotation is embodied at least partly as a structuring of a section of the metal jacket that is not rotationally symmetrical to the central axis of the heating element. On a section of the metal jacket, which is in contact with the pourable sealing compound, a recess or elevation or projection is then arranged, which prevents a simple “full rotation” of the metal jacket in relation to the pourable sealing compound. As an alternative, the same effect can be achieved or the effect can be additionally reinforced when the end section of the metal jacket, which is in contact with the pourable sealing compound, is deformed such that it no longer has rotational symmetry. 
         [0021]    As an alternative or in addition, the means for securing against rotation can be embodied at least partly as a structuring of a section of the connecting element that is not rotationally symmetrical to the central axis of the heating element, when the connecting element is positioned on the heating element. On a section of the connecting element, which is in contact with the pourable sealing compound, a recess or elevation or projection is then arranged, which prevents a simple “full rotation” of the connecting element in relation to the pourable sealing compound. As an alternative, the same effect can be achieved or the effect can be additionally reinforced when the section of the connecting element, which is in contact with the pourable sealing compound, is deformed such that it no longer has rotational symmetry. 
         [0022]    Especially in electrical heating elements, which are operated with high currents and therefore have relatively thick and stiff electrical connections, the means for securing against rotation may also be embodied at least partly as an arrangement of the at least one electrical connection that is not rotationally symmetrical to the central axis of the heating element. This embodiment is especially inexpensive in the manufacture, since it does not need any additional processing steps for the metal jacket and/or connecting element. 
         [0023]    As is explained by the phrase “at least partly” in the description of the above three embodiments, these measures may also be combined to guarantee an especially good means for securing against rotation. 
         [0024]    Especially preferred in this connection are means for securing against rotation, in which at least one structuring of a section of the connecting element meshes with at least one structuring of a section of the metal jacket or embraces same. 
         [0025]    One possibility of achieving an especially high mechanical stability of the connection is given when the cavity has a partial area, which is defined by an outer jacket surface of the metal jacket. 
         [0026]    An alternative or additional possibility for increasing the mechanical stability is that the electrical heating element has, on an end-side section of the metal jacket within the metal jacket, at least one cavity, which passes into the at least one cavity of the connecting element, and that these cavities are at least partly cast with the pourable sealing compound. 
         [0027]    For clarification, it is pointed out that the phrase “within the metal jacket” only means that the heating element or heating elements passes/pass through a space, for which the metal jacket forms a jacket surface. 
         [0028]    The electrical heating element is especially cost-effective when the connecting element is made of plastic. In the conventional manner of fastening by means of welding, soldering or pressing, the use of this material is not possible or the strength of the connection achieved is unsatisfactory. In the injection molding of the connection element made of plastic, a corresponding contact has to be present with the necessary forms for any desired connecting element at the manufacturer, while in the heating element embodied according to the present invention for using connecting elements made of plastic, only the connecting elements have to be prepared, e.g., by a supplier. 
         [0029]    Especially firm connections between the connecting element and electrical heating element can be achieved when the connecting element and/or metal jacket have a contour shape, especially an undercut, a notch, a bulging out, a knurling, a hole, or a score on its end section having the cavity. 
         [0030]    Connecting elements that have an external thread or mounting holes can be used especially well. In this case, the heating element can be fastened by means of a simple screwing in at a counterthread at the device, which shall achieve the heating function, or by passing holding elements, e.g., screws or pins through the mounting holes. 
         [0031]    An electrical heating element especially well protected against the penetration of moisture is obtained when the electrical connection of the electrical heating element has a contact element on the end side, which is in electrical connection with a supply line, and when the contact element and at least the section of the supply line incorporated into the contact element are embedded into the pourable sealing compound. 
         [0032]    The process according to the present invention for manufacturing an electrical heating element with a metal jacket, a connecting element lying on the metal jacket on at least some sections and at least one electrical connection has at least the following steps: preparing an electrical heating element with a metal jacket and at least one electrical connection, preparing a connecting element that can be arranged on at least one section of the metal jacket, which has at least one section, with which it lies on the metal jacket in the state arranged on the metal jacket and which has at least one cavity; 
         [0000]    arranging the connecting element on a section of the metal jacket, wherein the arranging takes place in such a way that the at least one cavity borders on a section of the metal jacket, e.g., its front side, and/or on a section of the electrical connection at least on some sections; and
 
at least partial casting of the cavity with a pourable sealing compound, especially with a ceramic cement, an epoxy resin or plastic, such that a direct, supporting mechanical connection between the metal jacket and the connecting element and/or between the section of the electrical connection and the connecting element is produced, such that the pourable sealing compound is in contact with a means for securing against rotation provided at the prepared heating element and/or at the prepared connecting element.
 
         [0033]    As mentioned above, this manufacturing process is markedly more cost-effective than prior-art alternatives. Furthermore, the thermal stress during casting with a pourable sealing compound is markedly less than the stress occurring during welding, soldering or injection molding; a mechanical stress as when pressing on the connecting element does not develop. Therefore, the manner of connection according to the present invention is especially suitable for avoiding damage to installed sensors, securing elements and switches, as well as to stranded wire insulation and/or pourable sealing compound. At the same time, it is a cost-effective solution, especially also since the operation of welding, soldering or pressing is entirely omitted. 
         [0034]    To prepare the means for securing against rotation, a structuring of a section of the metal jacket that is not rotationally symmetrical to the central axis of the heating element can be embodied before or after preparation of the heating element but before casting and/or a structuring of a section of the connecting element that is not rotationally symmetrical to the central axis of the heating element can be embodied before or after preparation of the connecting element but before casting and/or an electrical heating element is prepared, which has an arrangement of the at least one electrical connection that is not rotationally symmetrical to the central axis of the heating element. 
         [0035]    As is explained by the phrase “at least partly” in the description of the above three embodiments, these measures may also be combined to guarantee an especially good means for securing against rotation. 
         [0036]    An embodiment of the process that leads to more stable connections provides that the connecting element is arranged on the section of the metal jacket, such that the cavity has a partial area, which is defined by an outer jacket surface of the metal jacket. 
         [0037]    The stability of the connection can be even further increased when at least one cavity is provided in the electrical heating element with metal jacket on an end-side section of the metal jacket within the metal jacket, that the connecting element is arranged such that the cavity passes over into the at least one cavity of the connecting element, and that the at least partial casting takes place such that both cavities are at least partly cast with a pourable sealing compound. 
         [0038]    The process is especially cost-effective if a connection between the metal jacket and a connecting element made of plastic is produced by the casting. 
         [0039]    Especially firm and stable connections are achieved when a contour shape, especially an undercut, a notch, a bulging out, a knurling, or a score is provided in the connecting element and/or in the metal jacket at its end section having the cavity. 
         [0040]    It is especially advantageous when the contour shape is provided after arranging the connecting element on the metal jacket of the heating element and before casting with epoxy resin or plastic, since this makes possible the use of contour shapes, which prevent the later arrangement of the connecting element. This is, e.g., the case when the arranging shall take place by pushing on the connecting element and an expansion of the metal jacket is provided in some sections. 
         [0041]    Electrical heating elements especially well protected against the penetration of moisture are obtained, when a contact element, which has an electrical connection on an end side, is brought into electrical connection with a supply line before casting, and when the contact element and at least the section of the supply line incorporated into the contact element are embedded into the pourable sealing compound during the casting. 
         [0042]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0043]    In the drawings: 
           [0044]      FIG. 1   a  is a view of the end area of a first exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0045]      FIG. 1   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 1   a;    
           [0046]      FIG. 2   a  is a view of the end area of a second exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0047]      FIG. 2   b  is a front view of the connecting element of the exemplary embodiment from  FIG. 2   a;    
           [0048]      FIG. 3   a  is a view of the end area of a third exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0049]      FIG. 3   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 3   a;    
           [0050]      FIG. 4   a  is a view of the end area of a fourth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0051]      FIG. 4   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 4   a;    
           [0052]      FIG. 5   a  is a view of the end area of a fifth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0053]      FIG. 5   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 5   a;    
           [0054]      FIG. 6   a  is a view of the end area of a sixth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0055]      FIG. 6   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 6   a;    
           [0056]      FIG. 7   a  is a view of the end area of a seventh exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0057]      FIG. 7   b  is a view of a cutout enlargement of  FIG. 7   a;    
           [0058]      FIG. 8   a  is a view of the end area of a eighth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0059]      FIG. 8   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 8   a;    
           [0060]      FIG. 9   a  is a view of the end area of a ninth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0061]      FIG. 9   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 9   a;    
           [0062]      FIG. 10   a  is a view of the end area of a tenth exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; 
           [0063]      FIG. 10   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 10   a;    
           [0064]      FIG. 11   a  is a view of the end area of a eleventh exemplary embodiment of the present invention, wherein the end-side section of the end area is shown cut open; and 
           [0065]      FIG. 11   b  is a front view of the connecting element of the exemplary embodiment of  FIG. 11   a.    
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0066]    In all figures identical reference numbers are used for identical components of identical exemplary embodiments. 
         [0067]    Referring to the drawings in particular,  FIG. 1   a  shows a view of the end area A of a first exemplary embodiment of an electrical heating element  10  according to the present invention, wherein the end-side section B of the end area of the electrical heating element  10  is shown cut open. A section (not shown) of the electrical heating element  10  continues this to the right in the view shown, it may have any shape, and be especially straight, bent, coiled or meandering. One recognizes a metal jacket  11  and electrical connections  13  and  14 , which form the electrical connection to a hot wire, hot coil or resistance wire arranged in the interior of the heating element. The metal jacket  11  is usually embodied as tubular, it may have a circular cross section, especially as shown here, but also a different, e.g., oval or polygonal, especially triangular, rectangular or square cross section. The electrical connections  13  and  14 , but at least the hot wires connected thereto, are embedded within the metal jacket  11  in a medium at least in some sections. It is typically MgO, but other materials are also conceivable. The hot wires may also be wound up on a carrier or pressed into same, wherein the carrier for its part may then be in turn optionally embedded in a medium or be part of a layered structure. 
         [0068]    At the end section of the metal jacket  11  is arranged a notch  12 , i.e., a narrow section of the edge area is bent inwards, while the adjacent section in the radial direction is not bent. Furthermore, it has on the end side a cavity  19 , which is not filled with the medium  15 . 
         [0069]    Further, a connecting element  16  is shown, which lies on the metal jacket  11  with a section  17  and has a cavity  19 ′, which passes over into the cavity  19 . The electrical connections  13  and  14  are passed through this cavity. A separating line between the cavities  19  and  19 ′ is shown dashed in  FIG. 1   a  for illustration. Aside from the volume occupied by the passed-through connections  13 ,  14 , the cavities  19  and  19 ′ are completely cast with pourable sealing compound  18 , as a result of which a rigid, especially firm connection is brought about between the connecting element  16  and the metal jacket  11 . 
         [0070]    Further, the cavity  19 ′ has a partial area  19 ″, which is defined by an outer jacket surface of the metal jacket  11  and is likewise cast with pourable sealing compound  18 . This enlarges the surface, on which a contact is present between pourable sealing compound  18  and metal jacket  11 , which brings with it a stronger mechanical hold. 
         [0071]    The means for securing against rotation is embodied in this exemplary embodiment by means of the combination of two independent measures: On the one hand, the electrical connections  13 ,  14  are arranged not rotationally symmetrical to the central axis of the heating element  10  shown in  FIGS. 1   a  through  8   a  as broken line with consecutive long and short segments. This measure, which is also present in all other exemplary embodiments, but is not absolutely necessary, already results in that a full rotation of the pourable sealing compound  18  in relation to the metal jacket  11  is prevented, because, for this, either the electrical connections  13 ,  14  would have to be deformed or separated, or pourable sealing compound  18  would have to be split by the electrical connections  13 ,  14 . Thus, increased torsional strength is achieved. 
         [0072]    On the other hand, with the notch  12 , a structuring of a section of the metal jacket  11  that is not rotationally symmetrical to the central axis of the heating element  10  is present, which likewise permits a full rotation of the pourable sealing compound  18  in relation to the metal jacket only by deforming or separating the notch  12  or splitting the pourable sealing compound  18  and thus leads to increased torsional strength. 
         [0073]      FIG. 1   b  shows a front view of the connecting element  16  of the exemplary embodiment of  FIG. 1   a . One recognizes the pourable sealing compound  18  as well as the connections  13 ,  14  passed through it. 
         [0074]      FIG. 2   a  shows a view of the end area A of a second exemplary embodiment of an electrical heating element  20  according to the present invention, wherein the end-side section B of the end area A of the electrical heating element  20  is shown cut open. A section (not shown) of the electrical heating element  20  continues this to the right as in the view shown in  FIG. 1   a.    
         [0075]    One recognizes a metal jacket  21  and electrical connections  23  and  24 . The metal jacket  21  is usually embodied as in the above-described first exemplary embodiment. The connections  23  and  24  are embedded within the metal jacket  21  in a medium  25  at least in some sections, possible details of this embedding were already described based on the first exemplary embodiment. 
         [0076]    The end section of the metal jacket  21  has on the end side a cavity  29 , which is not filled with the medium  25 . 
         [0077]    Further, a connecting element  26  is shown, which lies on the metal jacket  21  with a section  27  and has a cavity  29 ′, which passes over into the cavity  29 . The electrical connections  23  and  24  are passed through this cavity. A separating line between the cavities  29  and  29 ′ is shown dashed in  FIG. 2   a  for illustration. Aside from the volume occupied by the passed-through connections  23 ,  24 , the cavities  29  and  29 ′ are completely cast with pourable sealing compound  28 , as a result of which a rigid, especially firm connection between the connecting element  26  and the metal jacket  21  is brought about. Further, the cavity has a bulge  22 , which can be used as an orientation aid or matching structure, when the electrical heating element has to be arranged in a preset orientation. 
         [0078]    With the bulge  22 , a structuring of a section of the connecting element  26  that is not rotationally symmetrical to the central axis of the heating element  20  is also present, which interacts with the pourable sealing compound  28 . Thus, a full rotation of the pourable sealing compound  28  in relation to the connecting element  26  is made possible only by deforming the bulge  22  or splitting the pourable sealing compound  28  and thus brings about increased torsional strength. 
         [0079]    Further, the cavity  29 ′ has a partial area  29 ″, which is defined by an outer jacket surface of the metal jacket  21  and is likewise cast with pourable sealing compound  28 . This enlarges the surface, on which a contact is present between pourable sealing compound  28  and metal jacket  21 , which brings with it a stronger mechanical hold. 
         [0080]      FIG. 2   b  shows a front view of the connecting element  26  of the exemplary embodiment of  FIG. 2   a . One recognizes the pourable sealing compound  28  as well as the connections  23 ,  24  passed through it besides the symmetry-breaking bulge  22 . 
         [0081]      FIG. 3   a  shows a view of the end area A of a third exemplary embodiment of an electrical heating element  30  according to the present invention, wherein the end-side section B of the end area A of the electrical heating element  30  is shown cut open. A section (not shown) of the electrical heating element  30  continues this to the right as in the view shown in  FIG. 1   a.    
         [0082]    One recognizes a metal jacket  31  and electrical connections  33  and  34 . The metal jacket  31  is usually embodied as in the above-described first exemplary embodiment. The electrical connections  33  and  34  are embedded within the metal jacket  31  in a medium  35  at least in some sections, possible details of this embedding were already described based on the first exemplary embodiment. 
         [0083]    The end section of the metal jacket  31 , which shows a circumferential bulging out  32  at its end, has on the end side a cavity  39 , which is not filled with the medium  35 . 
         [0084]    Further, a connecting element  36  is shown, which lies on the metal jacket  31  with a section  37  and has cavities  39 ′ and  39 ′″, wherein the cavity  39 ′ passes over into the cavity  39 . The connections  33  and  34  are passed through this cavity. A separating line between the cavities  39  and  39 ′ is shown dashed in  FIG. 3   a  for illustration. Aside from the volume occupied by the passed-through connections  33 ,  34 , the cavities  39  and  39 ′ are cast with pourable sealing compound  38 , as a result of which a rigid, especially firm connection between the connecting element  36  and metal jacket  31  is brought about. The cavity  39 ′″ is not cast. 
         [0085]    Further, the cavity  39 ′ has a partial area  39 ″, which is defined by an outer jacket surface of the metal jacket  31  and is likewise cast with pourable sealing compound  38 . This enlarges the surface, on which a contact between pourable sealing compound  38  and metal jacket  31  is present, which brings with it a stronger mechanical hold. 
         [0086]      FIG. 3   b  shows a front view of the connecting element  36  of the exemplary embodiment of  FIG. 3   a . One recognizes the pourable sealing compound  38  as well as the connections  33 ,  34  passed through it. 
         [0087]      FIG. 4   a  shows a view of the end area A of a fourth exemplary embodiment of an electrical heating element  40  according to the present invention, wherein the end-side section B of the end area A of the electrical heating element  40  is shown cut open. A (not shown) section of the electrical heating element  40  continues this to the right as in the view shown in  FIG. 1   a.    
         [0088]    One recognizes a metal jacket  41  and electrical connections  43  and  44 . The metal jacket  41  is usually embodied as in the above-described first exemplary embodiment. The electrical connections  43  and  44  are embedded within the metal jacket  41  in a medium  45  at least in some sections, possible details of this embedding were already described based on the first exemplary embodiment. 
         [0089]    The end section of the metal jacket  41  has on the end side a cavity  49 , which is not filled with the medium  45 . 
         [0090]    Further, a connecting element  46  is shown, which lies on the metal jacket  41  with a section  47  and has a cavity  49 ′, which passes over into the cavity  49 . The electrical connections  43  and  44  each pass over into this cavity in a contact element  42 . The contact elements  42  make the contact with supply lines  141 ,  142  for the electrical connections  43 ,  44 , which are provided in the cavity  49 ′ of the connecting element  46  from the connection-side direction. 
         [0091]    A separating line between the cavities  49  and  49 ′ is shown dashed in  FIG. 4   a  for illustration. Aside from the volume occupied by the passed-through connections  43 ,  44 , the contact elements  42  and the supply lines  141 ,  142 , the cavities  49  and  49 ′ are completely cast with pourable sealing compound  48 , as a result of which a rigid, especially firm connection between the connecting element  46  and the metal jacket  41  is brought about. At the same time, it is consequently achieved that the electrical connection between the supply lines  141 ,  142  and the connections  43 ,  44  is fixed via the contact elements  42 , and that the sealing against penetration of moisture is improved. 
         [0092]    Further, the cavity  49 ′ has a partial area  49 ″, which is defined by an outer jacket surface of the metal jacket  41  and is likewise cast with pourable sealing compound  48 . This enlarges the surface, on which a contact between pourable sealing compound  48  and metal jacket  41  is present, which brings with it a stronger mechanical hold. 
         [0093]      FIG. 4   b  shows a front view of the connecting element  46  of the exemplary embodiment of  FIG. 4   a . One recognizes the pourable sealing compound  48  as well as the supply lines  141 ,  142  passed through it. 
         [0094]    The connecting elements  16 ,  26 ,  36  and  46  of the four above-described embodiments according to  FIGS. 1   a  through  4   b  advantageously have an external thread, with which the electrical heating element can be fixed in a corresponding counterthread arranged at a device. 
         [0095]      FIG. 5   a  shows a view of the end area A of a fifth exemplary embodiment of an electrical heating element  50  according to the present invention, wherein the end-side section B of the end area A of the electrical heating element  50  is shown cut open. A (not shown) section of the electrical heating element  50  continues this to the right as in the view shown in  FIG. 1   a.    
         [0096]    One recognizes a metal jacket  51  and electrical connections  53  and  54 . The metal jacket  51  is usually embodied as in the above-described first exemplary embodiment. The electrical connections  53  and  54  are embedded within the metal jacket  51  in a medium  55  at least in some sections, possible details of this embedding were already described based on the first exemplary embodiment. 
         [0097]    The end section of the metal jacket  51 , which shows a circumferential bulging out  60  at its end, has on the end side a cavity  59 , which is not filled with the medium  55 . 
         [0098]    Further, a connecting element  56  is shown, which lies on the metal jacket  51  with a section  57  and has a cavity  59 ′, wherein said cavity  59 ′ passes over into the cavity  59 . The electrical connections  53  and  54  are passed through this cavity. A separating line between the cavities  59  and  59 ′ is shown dashed in  FIG. 5   a  for illustration. Aside from the volume occupied by the electrical connections  53 ,  54  passed through, the cavities  59  and  59 ′ are cast with pourable sealing compound  58 , as a result of which a rigid, especially firm connection is brought about between the connecting element  56  and the metal jacket  51 . 
         [0099]    Further, the connecting element  56  has mounting holes  52 , which pass through it in a section overhanging the metal jacket  51  in the extension direction of the connections  53 ,  54 . By means of these mounting holes  52 , a fixing of the electrical heating device to a device by means of screws or pins is possible. 
         [0100]      FIG. 5   b  shows a front view of the connecting element  56  of the exemplary embodiment of  FIG. 5   a . One recognizes the pourable sealing compound  58  as well as the connections  53 ,  54  passed through it and the mounting holes  52 . 
         [0101]    Further, the cavity  59 ′ has a partial area  59 ″, which is defined by an outer jacket surface of the metal jacket  51  and is likewise cast with pourable sealing compound  58 . This enlarges the surface, on which a contact is present between pourable sealing compound  58  and metal jacket  51 , which brings with it a stronger mechanical hold. 
         [0102]    Moreover, one also recognizes in  FIG. 5   b  the presence of a second component of a means for securing against rotation besides the not rotationally symmetrical arrangement of the electrical connections  53 ,  54 . The connecting element has a section in the form of a square with rounded angles, which is filled with the pourable sealing compound  58 . Thus, a structuring of a section of the connecting element  56  that is at least partly not rotationally symmetrical to the central axis of the heating element  50  is present, which is in contact with the pourable sealing compound  58  and thus provides torsional strength. 
         [0103]    The embodiment, which is shown in  FIGS. 6   a  and  6   b , corresponds almost completely to the embodiment of  FIGS. 2   a  and  2   b , to whose description reference is made. The difference lies in that in this embodiment the area surrounded by the metal jacket  61  does not have a cavity and that the cavity  69 ′ of the connecting element  66  does not have a partial area that is defined by an outer jacket surface of the metal jacket  61 . The mechanical connection between connecting element  66  and the electrical heating element with metal jacket is made here only by the interaction of the pourable sealing compound  68  with the front surfaces of the metal jacket and with the connections  63 ,  64 . It turned out that the interaction with front surfaces of the metal jacket  61  is also not absolutely necessary to guarantee a stable connection. 
         [0104]    The embodiment that is shown in  FIGS. 7   a  and  7   b  corresponds almost completely to the embodiment of  FIGS. 2   a  and  2   b , to whose description reference is made. The difference is that in this embodiment the end section of the metal jacket  71  in the area, in which the metal jacket  71  surrounds the cavity  79 , has a hole  72   a . The provision of this hole  72   a  improves the mechanical connection between connecting element  76  and the electrical heating element with metal jacket  71  especially in terms of its tensile strength and torsional strength, since a structuring of a section of the metal jacket that is not rotationally symmetrical to the central axis of the heating element is thus present, with which the pourable sealing compound  78  meshes, so that a means for securing against rotation is formed. 
         [0105]    The embodiment, which is shown in  FIGS. 8   a  and  8   b , corresponds almost completely to the embodiment of  FIGS. 2   a  and  2   b , to whose description reference is made. The difference is that in this embodiment, instead of the recess  22 , a score  82  is provided in the connecting element  86 , which is likewise cast with pourable sealing compound  88 . The provision and casting of this score  82  improves the mechanical connection between connecting element  86  and the electrical heating element with metal jacket  81  likewise especially in terms of its tensile strength. 
         [0106]    The embodiment, which is shown in  FIGS. 9   a  and  9   b , corresponds almost completely to the embodiment of  FIGS. 1   a  and  1   b , to whose description reference is made. The first essential difference between the embodiments is that two notches  92   a ,  92   b  are provided, which represent a structuring of a section of the metal jacket  91  that is not rotationally symmetrical to the central axis of the heating element  90 , which likewise permits a full rotation of the pourable sealing compound  98  in relation to the metal jacket only by deforming or separating the notches  92   a ,  92   b  or splitting the pourable sealing compound  98  and thus leads to increased torsional strength. 
         [0107]    The second essential difference between the embodiments, which can only be clearly recognized in  FIG. 9   b , is that the cavity  99  provided in the connecting element  96  has two bulges  92   c ,  92   d , with which the pourable sealing compound  98  meshes. 
         [0108]    Thus, a structuring of a section of the connecting element  96  that is not rotationally symmetrical to the central axis of the heating element  90  is also present, which interacts with the pourable sealing compound  98 . Thus, a full rotation of the pourable sealing compound  98  in relation to the connecting element  96  is made possible only by deforming the bulges  92   c ,  92   d  or splitting the pourable sealing compound  98  and thus brings about increased torsional strength. Thus, a rotation of the pourable sealing compound  98  in relation to the connecting element  96  is not possible in this embodiment even when higher torques act on the connecting element  96 . 
         [0109]    Even higher torsional strength is achieved in the embodiment, which is shown in  FIGS. 10   a  and  10   b . This embodiment also corresponds almost completely to the embodiment of  FIGS. 1   a  and  1   b , to whose description reference is made. The first essential difference between the embodiments is that, instead of a notch, three local reinforcements  102   a ,  102   b ,  102   c , which are embodied as square by way of example, are provided here at the end section of the metal jacket  101 , which represent a structuring of a section of the metal jacket  101  that is not rotationally symmetrical to the central axis of the heating element  100 . 
         [0110]    The second essential difference between the embodiments, which can only be recognized clearly in  FIG. 10   b , is that the cavity  109  provided in the connecting element  106  has three bulges  102   d ,  102   e ,  102   f , in which are mounted the reinforcements  102   a ,  102   b ,  102   c . Optionally, provisions may also be made for the mounting to take place in an accurately matching manner, but it is preferable that pourable sealing compound  108  is also present in each of the bulges  102   d ,  102   e ,  102   f , which fills especially a space between the reinforcements  102   a ,  102   b ,  102   c  and the respective wall of the bulges  102   d ,  102   e ,  102   f.    
         [0111]    Thus, a structuring of a section of the connecting element  106  that is not rotationally symmetrical to the central axis of the heating element  100  is also present, which interacts with the pourable sealing compound  108 . Thus, a relative rotation of the components to one another is not possible in this embodiment even when applying very high torques. 
         [0112]    The embodiment, which is shown in  FIGS. 11   a  and  11   b , corresponds almost completely to the embodiment of  FIGS. 1   a  and  1   b , to whose description reference is made. The first essential difference between the embodiments is that, instead of a notch, an oval deformation  112   a  of the end section of the metal jacket  111  is provided here, which represents a structuring of a section of the metal jacket  111  that is not rotationally symmetrical to the central axis of the heating element  110 . 
         [0113]    The second essential difference between the embodiments, which can only be clearly recognized in  FIG. 11   b , is that the cavity  119  provided in the connecting element  116  has an approximately oval shape and in addition two bulges  112   b ,  112   c . Thus, a structuring of a section of the connecting element  116  that is not rotationally symmetrical to the central axis of the heating element  110  is also present, which interacts with the pourable sealing compound  118 , and because of the oval shape, a rotation of the individual components is reliably prevented even when applying very high torques. 
         [0114]    As is clearly evident from the above-described exemplary embodiments, the number and shape of structures that are provided at the end section of the metal jacket and/or in the connecting element may especially be varied. Of course, for example, the embodiment according to  FIGS. 10   a  and  10   b  can also be embodied with only one reinforcement and one recess, and likewise, of course, notches may be provided directed radially outwards or reinforcements may be provided on the inside of the metal jacket. 
         [0115]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of Reference Numbers 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 A 
                 End area 
               
               
                 B 
                 End-side section of the end 
               
               
                   
                 area 
               
               
                 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 
                 Electrical heating element 
               
               
                 11, 21, 31, 41, 51, 61, 71, 81, 91, 101, 111 
                 Metal jacket 
               
               
                 13, 14, 23, 24, 33, 34, 43, 44, 53, 54, 63, 64, 
                 Electrical connection 
               
               
                 73, 74, 83, 84, 93, 94, 103, 104, 113, 114 
               
               
                 15, 25, 35, 45, 55, 65, 75, 87, 95, 105, 115 
                 Medium 
               
               
                 16, 26, 36, 46, 56, 66, 76, 86, 96, 106, 116 
                 Connecting element 
               
               
                 17, 27, 37, 47, 57, 67, 77, 87, 97, 107, 117 
                 Section of the connecting 
               
               
                   
                 element 
               
               
                 18, 28, 38, 48, 58, 68, 78, 88, 98, 108, 118 
                 Pourable sealing compound 
               
               
                 19, 19′, 19″, 29, 29′, 29″, 39, 39′, 39″, 39′″, 
                 Cavity 
               
               
                 49, 49′, 49″, 59, 59, 59″, 69′, 79, 79′, 79″, 
               
               
                 89, 89′, 89″, 99, 99′, 99″, 109, 109′, 109″, 
               
               
                 119, 119′, 119″ 
               
               
                 12, 92a, 92b 
                 Notch 
               
               
                 22, 102d, 102e, 102f, 112b, 112c 
                 Bulge 
               
               
                 32, 62 
                 Bulging out 
               
               
                 102a, 102b, 102c 
                 Reinforcements 
               
               
                 112a 
                 Oval deformation 
               
               
                 42 
                 Contact element 
               
               
                 52 
                 Mounting hole 
               
               
                 72a 
                 Hole 
               
               
                 82 
                 Score 
               
               
                 141, 142 
                 Supply line