METHOD OF MANUFACTURING AN ELECTRIC HEATER AND ELECTRIC HEATER

Abstract

Disclosed is a method for producing an electrical heating device with an electrical heating element, which is arranged in the interior of a multi-part tubular metal jacket embedded in an electrically insulating material, wherein the electrical heating device has, within the multi-part tubular metal jacket, on at least one end, an unheated area, in which, during operation of the electrical heating device, electrical current flows at least also through at least one connection wire, and/or at least one connection sleeve and/or at least one connection pin, which is in electrical contact with the electrical heating element, and further has a heated area, in which, during operation of the electrical heating device, electrical current flows only through a section of the electrical heating element running in the heated area. An electrical heating device with a multi-part tubular metal jacket, which can be produced with this method, is also disclosed.

Claims

1. A method for producing an electrical heating device with an electrical heating element, which is arranged in an interior of a multi-part tubular metal jacket embedded in an electrically insulating material, wherein the electrical heating device has, within the multi-part tubular metal jacket, on at least one end, an unheated area, in which, during operation of the electrical heating device, electrical current flows at least also through at least one connection wire, and at least one connection sleeve and at least one connection pin, which is in electrical contact with the electrical heating element and further has a heated area, in which, during operation of the electrical heating device, electrical current flows only through a section of the electrical heating element running in the heated area, wherein, in the method, in a first method step, the heated area is produced and compressed in a first part of the multi-part tubular metal jacket, and in a second method step performed independently from the first method step, at least one section of the unheated area is produced in a second part of the multi-part tubular metal jacket, and the first part and the second part of the multi-part tubular metal jacket are connected to each other.

2. The method for producing the electrical heating device according to claim 1, wherein in the first method step the section of the electrical heating element running in the heated area is positioned in the first part of the multi-part tubular metal jacket, the electrically insulating material is inserted into an area of the first part of the multi-part tubular metal jacket, so that a section of the electrical heating element arranged in the first part of the multi-part tubular metal jacket is insulated by the electrically insulating material, and the first part of the multi-part tubular metal jacket, in particular, the heated area, is compressed.

3. The method for producing the electrical heating device according to claim 1, wherein the unheated area comprises an unheated transition area, in which, during operation of the electrical heating device, electrical current flows simultaneously both through the at least one connection wire and the at least one connection pin and also through a section of the electrical heating element running in the unheated transition area, which is in electrical contact with the at least one connection wire and the at least one connection sleeve and the at least one connection pin, and that, in the method, in the second method step performed independently from the first method step, at least one section of the unheated area including at least one part of the unheated transition area is created, in that a section of the electrical heating element is introduced with the at least one connection wire arranged thereon and the at least one connection sleeve arranged thereon and the at least one connection pin arranged thereon in the second part of the multi-part tubular metal jacket, in that the electrically insulating material is introduced into the second part of the multi-part tubular metal jacket, so that the section of the electrical heating element arranged in the second part of the multi-part tubular metal jacket is embedded in the electrically insulating material.

4. The method according to claim 1, wherein in the first method step, the at least one connection wire is brought into an electrically conductive connection with an end section of the electrical heating element, in particular, by introduction into a coiled end section of the electrical heating element, and that, in the first method step, the at least one connection sleeve is made from metal and is brought into an electrically conductive connection with the end section of the electrical heating element, in particular, by pushing, soldering, or welding the at least one connection sleeve onto the coiled end section of the electrical heating element.

5. The method according to claim 1, wherein in the second method step, the second part of the multi-part tubular metal jacket is compressed with components arranged therein a second compression, wherein the second compression is carried out so that, through an axial pressing pressure, a nearly homogeneous transition area is provided between the electrically insulating material in areas that were subjected to the compression in the first method step and the electrically insulating material in areas that were subjected to the second compression in the second method step.

6. The method according to claim 1, wherein the electrical heating element is coiled such that an end section of the electrical heating element has a smaller coil diameter than a section of the electrical heating element, which lies in the heated area in a finished electrical heating device.

7. The method according to claim 1, wherein when producing the second part of the multi-part tubular metal jacket, a feedthrough that has an internal conductor electrically insulated from an outer tube made from metal is used.

8. The method according to claim 1, wherein an internal conductor of the second part of the multi-part tubular metal jacket on a side facing the first part of the tubular metal jacket is machined with shape cutting, provided with an annular groove or drilled and that electrical contact to the electrical heating element is created directly or by means of the at least one connection wire, in that a section of the electrical heating element or the at least one connection wire is inserted and forms a press contact in a section of the internal conductor of the second part of the multi-part tubular metal jacket processed in this way.

9. An electrical heating device, which can be produced according to claim 1, with the electrical heating element, which has, in the interior, the multi-part tubular metal jacket, that has the first part and the second part, embedded in the electrically insulating material, wherein during operation of the electrical heating device, electrical current flows only through the section the electrical heating element running in the heated area, wherein the heated area is arranged in the first part of the multi-part tubular metal jacket and the unheated area is arranged in the second part of the multi-part tubular metal jacket.

10. The electrical heating device according to claim 9, wherein the unheated area comprises the unheated transition area, in which, during operation of the electrical heating device, electrical current flows simultaneously both through the at least one connection wire and the at least one connection sleeve and the at least one connection pin and also through the section of the electrical heating element running in the unheated transition area, which is in electrical contact with the at least one connection wire and the at least one connection sleeve and the at least one connection pin.

11. The electrical heating device according to claim 9, wherein characterized in that the at least one connection wire is in an electrically conductive connection with an end section of the electrical heating element, in particular, inserted in a coiled end section of the electrical heating elements.

12. The electrical heating device according to claim 9, wherein the at least one connection sleeve is made from metal and is brought into an electrically conductive connection with an end section of the electrical heating element, in particular, by pushing, soldering, or welding the at least one connection sleeve onto a coiled end section of the electrical heating element.

13. The electrical heating device according to claim 9, wherein the electrical heating element is coiled such that an end section of the electrical heating element has a smaller coil diameter than a section of the electrical heating element, which is in the heated area for a finished electrical heating device.

14. The electrical heating device according to claim 9, wherein characterized in that the second part of the multi-part tubular metal jacket has an open cross section, which can assume outer contours of an end section of the first part of the multi-part tubular metal jacket facing the second part at least after the compression in the first method step, is pushed onto and fixed on the end section of the first part of the multi-part tubular metal jacket.

15. The electrical heating device according to claim 9, wherein characterized in that a part of the electrical heating element with the at least one connection wire arranged thereon and with the at least one connection sleeve arranged thereon is inserted from one side into the second part of the multi-part tubular metal jacket and the at least one connection pin with an opening for receiving the part of the electrical heating element with the at least one connection wire arranged thereon and with the at least one connection sleeve arranged thereon is inserted from an opposite side into the second part of the multi-part tubular metal jacket and is pushed with the opening onto the part of the electrical heating element with the at least one connection wire arranged thereon and with the at least one connection sleeve arranged thereon.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0074] The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the preferred invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0075] FIG. 1a is a side perspective, partially transparent view of one half of an embodiment of an electrical heating device in accordance with a preferred embodiment of the present invention;

[0076] FIG. 1b is a longitudinal cross-section through the representation of the electrical heating device of FIG. 1a;

[0077] FIG. 1c is a first detailed enlargement from FIG. 1b, taken from within a left-circle of FIG. 1b;

[0078] FIG. 1d is a second detailed enlargement from FIG. 1b, taken from within a right-circle of FIG. 1b;

[0079] FIG. 2 is a side perspective view of a section of the electrical heating device in a first intermediate state during the execution of a first method for producing the electrical heating device of FIG. 1a;

[0080] FIG. 3 is a side perspective view of the section of the electrical heating device of FIG. 1a in a second intermediate state during the execution of the first method for producing the electrical heating device of FIG. 1a;

[0081] FIG. 4 is a side perspective view of a section of the electrical heating device of FIG. 1a in a third intermediate state during the execution of the first method for producing the electrical heating device of FIG. 1a;

[0082] FIG. 5 is a side perspective view of a section of the electrical heating device of FIG. 1a in a fourth intermediate state during the execution of the first method for producing the electrical heating device of FIG. 1a, which shows an intermediate product obtained after the first method step;

[0083] FIG. 6 is a side perspective view of a section of the electrical heating device of FIG. 1a in a fifth intermediate state during the execution of the first method for producing an electrical heating device of FIG. 1a;

[0084] FIG. 7a is a cross-sectional view of a first design of an end section of the electrical heating element of FIG. 1a;

[0085] FIG. 7b is cross-sectional view of a second design of an end section of the electrical heating element of FIG. 1a;

[0086] FIG. 7c is a cross-sectional view of a third design of an end section of the electrical heating element of FIG. 1a;

[0087] FIG. 8a is a cross-sectional view of a first design of an unheated transition area of the electrical heating element of FIG. 1a;

[0088] FIG. 8b is a cross-sectional view of a second design of an unheated transition area of the electrical heating element of FIG. 1a;

[0089] FIG. 8c is a cross-sectional view of a third design of an unheated transition area of the electrical heating element of FIG. 1a;

[0090] FIG. 9a is a side perspective view of a section of a second embodiment of an electrical heating device before joining a first part and a second part of a tubular metal jacket of an electrical heating device in accordance with the second preferred embodiment of the present invention;

[0091] FIG. 9b is a longitudinal cross-sectional view through the illustration of the section of the second embodiment of the electrical heating device of FIG. 9a;

[0092] FIG. 9c is a magnified cross-sectional view of the longitudinal section from FIG. 9b after the joining of the first and the second part of the tubular metal jacket;

[0093] FIG. 9d is a magnified cross-sectional view of the longitudinal section from FIG. 9c after a local pressing process;

[0094] FIG. 9e is a magnified cross-sectional view of a cutout enlargement of the longitudinal section from FIG. 9c;

[0095] FIG. 9f is a magnified cross-sectional view of a cutout enlargement of the longitudinal section from FIG. 9d;

[0096] FIG. 10a is a side perspective view of a first variant of the section of the second embodiment of the electrical heating element from FIGS. 9a-f before the joining of the first part and the second part of the tubular metal jacket;

[0097] FIG. 10b is a cross-sectional view of the first variant of the embodiment according to FIG. 10a after the joining of the first and the second part of the tubular metal jacket;

[0098] FIG. 11 is a cross-sectional view of a second variant of the section of the second embodiment of the electrical heating element from FIG. 9a-f after the joining of the first and second part of the tubular metal jacket;

[0099] FIG. 12 is a cross-sectional view of a third variant of the section of the second embodiment of the electrical heating element from FIG. 9a-f after the joining of the first and second part of the tubular metal jacket;

[0100] FIG. 13a is a longitudinal cross-sectional view through a section of a third embodiment of an electrical heating device before the joining of the first and second part of the tubular metal jacket;

[0101] FIG. 13b is a cross-sectional view of the longitudinal section from FIG. 13a after the joining of the first and second part of the tubular metal jacket;

[0102] FIG. 13c is a cross-sectional view of the longitudinal section from FIG. 13b after a local pressing process;

[0103] FIG. 14 is a side elevational section view of a first intermediate state during the execution of a second method for producing an electrical heating device;

[0104] FIG. 15a is a cross-sectional, partially exploded view of a second intermediate state during the execution of the second method for producing the electrical heating device in a first variant;

[0105] FIG. 15b is a side perspective, partial cross-sectional, partially exploded view of the section from FIG. 15a in a second variant;

[0106] FIG. 16 is a magnified partial cross-sectional view of a section of a third intermediate state during the execution of the second method for producing the electrical heating device in the first variant;

[0107] FIG. 17a is a magnified cross-sectional view of a section of a fourth intermediate state during the execution of the second method for producing the electrical heating device in the first variant;

[0108] FIG. 17b is a cross-sectional view of the section from FIG. 17a in the second variant;

[0109] FIG. 18 is a side elevational section view of a first intermediate state during the execution of a third method for producing an electrical heating device;

[0110] FIG. 19 is a cross-sectional, partially exploded view of a section of a second intermediate state during the execution of the third method for producing the electrical heating device;

[0111] FIG. 20 is a cross-sectional view of a section of a third intermediate state during the execution of the third method for producing the electrical heating device; and

[0112] FIG. 21 is a cross-sectional view of a section of a fourth intermediate state during the execution of the third method for producing the electrical heating device.

DETAILED DESCRIPTION OF THE INVENTION

[0113] FIG. 1a shows a half of an embodiment of an electrical heating device 10, whose second half can be symmetric to the first half and FIG. 1b shows a longitudinal section of this half, which, however, is slightly offset from the center plane. The electrical heating device 10 has a multi-part tubular metal jacket 11 with a first part 11.1 of the multi-part tubular metal jacket 11 and a second part 11.2 of the multi-part tubular metal jacket 11, which has a larger open cross section than the first part 11.1 of the multi-part tubular metal jacket, which overlaps this part in some sections, and which is connected to it, as illustrated, in particular, by the detailed representation of FIG. 1d.

[0114] In the interior of the first part 11.1 of the multi-part tubular metal jacket 11 is the heated area B, which is formed by the section of an electrical heating elements 12, in which electrical current flows only through this part during operation. An electrically insulating material 16 shown transparent here ensures the electrical insulation relative to the multi-part tubular metal jacket 11.

[0115] In the interior of the second part 11.2 of the multi-part tubular metal jacket 11, there is an unheated area U on the end side, which comprises an unheated transition area UE1. The unheated transition area UE1 is here formed by a section 12.1 of the electrical heating element 12, which is more tightly coiled than the electrical heating element 12 in the heated area, in which a connection wire 13 is inserted and pushed onto a connection sleeve 14, in which a connection pin 15 is held on its side in an opening 15.1, whose solid end section is in the unheated area U. This construction can be seen, e.g., by looking at FIGS. 1a and 1c. As can be seen from FIGS. 8a to 8c, however, not only the configuration with connection wire and connection sleeve described above and shown in FIG. 8c can be used, but optionally the connection wire 13, as shown in FIG. 8b, or the connection sleeve 14, as shown in FIG. 8a, can be left out.

[0116] Accordingly, during operation of the electrical heating device 10, electrical current flows in the unheated area U at least also through at least one connection wire 13, one connection sleeve 14, and/or one connection pin 15, which is in electrical contact with the electrical heating element 12, and the unheated area U also has an unheated transition area UE1, in which, during operation of the electrical heating device 10, electrical current flows simultaneously both through the at least one connection wire 13, the at least one connection sleeve 14, and/or the at least one connection pin 15 and also through a section 12.1 of the electrical heating element 12 running in the unheated transition area UE1, which is in electrical contact with the connection wire 13 and/or connection pin and has a smaller coil diameter. The unheated transition area extends into the first part 11.1 of the multi-part tubular metal jacket 11.

[0117] Also in the interior of the second part 11.2 of the multi-part tubular metal jacket 11 there is an electrically insulating material 17, which is shown transparent and ensures the insulation relative to the multi-part tubular metal jacket 11. On the end side, a plug 18 closes the second part 11.2 of the multi-part tubular metal jacket 11. The first part 11.1 of the multi-part tubular metal jacket 11 with the components of the electrical heating device 10 arranged therein and the second part 11.2 of the multi-part tubular metal jacket 11 with the components arranged therein of the electrical heating device 11 are each compressed in this example, but in different ways, in particular, to different degrees, preferably with a weaker compression of the second part 11.2 of the multi-part tubular metal jacket 11. However, the invention also comprises embodiments in which the second part 11.2 of the multi-part tubular metal jacket 11 with the components arranged therein is not compressed more.

[0118] A method for producing such an electrical heating device is now described, wherein individual intermediate states are shown in FIGS. 2 to 6.

[0119] Initially, as shown in FIG. 2, a coiled electrical heating element 12 is provided, which has, in this embodiment, an end section 12.1 coiled with a smaller coil diameter, in which, on the end side, a connection wire 13, e.g., made from Cu or Ni, is pushed in and which is shown again in cross section in FIG. 7a.

[0120] Other variants of electrical heating elements 12′ and 12″ can be seen in FIGS. 7b and 7c, respectively, which illustrate, in particular, that the electrical heating element 12′ does not necessarily have to taper on the end side or that the electrical heating element 12″ has an end-side section 12.1″, which has a smaller coil diameter and is coiled about a different coil axis W2 than coil axis W1, about which the coils with greater coil diameter are coiled, which are in the heated area b in the finished electrical heating device, more specifically, about a coil axis W2 offset parallel to coil axis W1.

[0121] Starting from the intermediate state shown in FIG. 2, now a thin-walled, electrically conductive connection sleeve 14 is pushed onto the end-side section 12.1 of the electrical heating element 12, which leads to the intermediate state shown in FIG. 3.

[0122] The electrical heating element 12 prepared in this way with connection wire 13 and connection sleeve 14 is now pushed into the first part 11.1 of the multi-part tubular metal jacket 11. Electrically insulating material 16 in the form of a powder or granulate is poured in and the arrangement is compressed, which leads to the intermediate state according to FIG. 4, which already shows a “finished” electrical tubular heating element of a conventional design, in which—differently than in the known tubular heating elements—the connections projecting out of the tubular metal jacket on the end side in the electrical heating device are formed by a section of the electrical heating element with connection wire arranged thereon and/or connection sleeve arranged thereon, and thus form the unheated transition section for the completely finished electrical heating device according to the invention.

[0123] As the next step, an end-side part of the first part 11.1 of the multi-part tubular metal jacket 11 is cut together with the electrically insulating material 16. The reason for this is that, during the compression process of the first part 11.1 of the multi-part tubular metal jacket 11, higher pressures can be processed, which leads to a more desirable intimate press-contact fit of the pressed section 12.1 of the electrical heating element 12 with the connection wire 13 and connection sleeve 14. Accordingly, it can be useful to carry out this pressure step initially in a longer section, but nevertheless there is still a sufficiently good ability to fill the electrically insulating material 16. This is also the reason why the whole section 12.1 of the electrical heating element 12 is not just embedded and pressed together at first; in this case, the improvement of being able to fill the electrically insulating material 16 would be largely lost.

[0124] To get from the intermediate state of FIG. 5 to the intermediate state of FIG. 6, the connection pin 15 is pushed with its opening 15.1 onto the arrangement made from section 12.1 of the electrical heating element 12 with pushed-on connection wire 13 and pushed-on connection sleeve 14.

[0125] The finished electrical heating device 1 shown in FIGS. 1a to 1 d is obtained from the intermediate state according to FIG. 6 in that the second part 11.2 of the multi-part tubular metal jacket 11 is pushed on until it overlaps the first part 11.1 of the multi-part metal jacket 11 and is fixed to this part and this part is then filled with electrically insulating material 17, closed with the plug 18, and preferably appropriately compressed.

[0126] FIGS. 9a to 9f show different views of a section of a second embodiment of an electrical heating device 100 with multi-part tubular metal jacket 101. The not-shown section has an essentially identical construction.

[0127] Here, FIGS. 9a and 9b show the electrical heating device 100 in a first intermediate state of its production before joining the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101.

[0128] The first part 111 of the tubular metal jacket 101 is here a part of an electrical heating device 110 produced in a known way, in whose interior there is an electrical heating element 112 in the shape of a coiled resistive wire, which is insulated by means of electrically insulating material 116 from the first part 111 of the tubular metal jacket 101. For the connection of the electrical heating elements 112, a connection wire 113, which projects out of the electrical heating element 112 on the end side, is pushed into the terminal coils of the electrical heating element 112 and in this example connected to it at the weld seam 114. The pushed-in section of the connection wire 113 thus defines an unheated transition area UE1, and the section of the connection wire 113, which runs within the first part 111 of the tubular metal jacket 101, forms a first part U1 of the unheated area U of the electrical heating device 100.

[0129] The second part 121 of the tubular metal jacket 101 is part of the second part U2 of the unheated area U of the electrical heating device 100. The second part U2 of the unheated area U is produced, in this example, from a section of a feedthrough 120, whose outer metal jacket is used as the second part 121 of the tubular metal jacket 101 of the electrical heating device 100, wherein, in its interior, an internal conductor 122 is arranged, which is electrically insulated by an electrically insulating material 125 from the outer metal jacket of the feedthrough 120. The internal conductor can preferably be made from nickel or copper. It is noted that such a feedthrough could also be mineral-insulated cables.

[0130] The feedthrough 120, which is produced in this example from extruded or band material, was cut to the length of this extruded or band material that corresponds to the sum of the desired length of the second part U2 of the unheated area and the desired length A of a connection of the electrical heating device 100. Furthermore, in the end side of the internal conductor 122 facing the first part 111 of the tubular metal jacket 101 there is a hole 123 for receiving the section of the connection wire 113 extending beyond the end side of the first part 111 of the tubular metal jacket and on the opposite side for forming the connection of length A, the feedthrough 120 and the electrically insulating material 125 is cut to this length of the outer metal jacket and preferably the surface of the internal conductor 122 is cleaned, e.g., by brushing, polishing, or ultrasonic processing. Here, the sequence in which these steps is performed is not important.

[0131] FIG. 9c shows a view of the longitudinal section from FIG. 9b after the joining of the first part 111 and the second part 121 of the tubular metal jacket 101. Here, the first part 111 and the second part 121 of the tubular metal jacket 101 were positioned against each other on the end sides and welded or soldered at the connection point 131.

[0132] Preferably, on the electrical heating device 100, as shown in FIG. 9c, another processing step is performed, whose result is shown clearly in FIG. 9d and FIG. 9f: another compression can also be realized as a local pressing process or repeated compression in the area of the second part 121 of the tubular metal jacket, preferably in the area in which the hole 123 with the section of the connection wire 113 arranged thereon is located, but at a distance from the connection point 131. This processing step can be concretely constructed, for example, as hexagonal crimping, in particular, through hammering, and is associated with two advantages:

[0133] The first advantage is that the electrical contact between the connection wire 113 and the internal conductor 122 is improved by a press-fit contact.

[0134] The second advantage that becomes clear especially by comparing the cutout enlargements of FIGS. 9e and 9f with each other is that, through the resulting axial pressing pressure, a nearly homogeneous transition area is produced between the electrically insulating material 115 and the electrically insulating material 125 and in particular, voids 132 and torn surfaces on the joined end sides can be filled.

[0135] In a first variant of the electrical heating device 100, which is shown in FIGS. 10a and 10b, the only difference is that the connection wire 113 has a thread 113a and the hole 123 has a cut counter thread 123a. Accordingly, a connection is realized by screwing in the parts before the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101 are welded or soldered to each other. All of the rest of the construction is identical, which is also why identical reference symbols are used.

[0136] In a second variant of the electrical heating device 100, which is shown in FIG. 11, the only difference to the illustration shown in FIG. 9c is that the end area 111a of the first part 111 of the tubular metal jacket 101 is made thinner on its side facing the second part 121 of the tubular metal jacket 101 by material-removing processing on its outer side, while the end area 121a of the second part 121 of the tubular metal jacket 101 is made thinner on its side facing the first part 111 of the tubular metal jacket 101 by material-removing processing on its inner side, so that a section of the end areas 111a and 121a overlap each other. This leads to improved protection against the penetration of moisture.

[0137] Furthermore, the end area 111a is longer than the end area 121a, which has the result that the weld seam or solder bead fixing the connection is arranged in a recess and the diameter of the electrical heating device is not increased.

[0138] All of the rest of the construction is identical, which is also why identical reference symbols are used.

[0139] In a third variant of the electrical heating device 100, which is shown in FIG. 12, the only difference to the illustration shown in FIG. 9d is that the connection between the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101 is the pushing on of a ring 133 and welding or soldering of the ring 133 at its edge with the second part 121 of the tubular metal jacket 101 and at its other edge on the first part 121 of the tubular metal jacket 101. This also leads to improved protection against the penetration of moisture.

[0140] FIGS. 13a to 13c each show a longitudinal section through a section of a third embodiment of an electrical heating device 200, wherein FIG. 13a shows the state before the joining of the first and second part of the tubular metal jacket, FIG. 13b shows the state after the joining of the first and the second part of the tubular metal jacket, and FIG. 13c is after another local compression step, e.g., hammering in hexagonal crimping.

[0141] The first part 211 of the tubular metal jacket 201 is, like for the electrical heating device 100, part of an electrical heating device 210 produced in a known way, with an electrical heating element 212 arranged in the interior in the form of a coiled resistive wire, which is insulated by means of electrically insulating material 216 from the first part 211 of the tubular metal jacket 201. For the connection of the electrical heating element 212, a connection wire 213, which projects out from the electrical heating element 212 on the end side, is pushed into the terminal coils of the electrical heating element 212 and, in this example, connected to it at the weld seam 214. The pushed-on section of the connection wire 213 defines an unheated transition area UE1, and the section of the connection wire 213, which runs within the first part 211 of the tubular metal jacket 201, forms a first part U1 of the unheated area U of the electrical heating device 200.

[0142] The second part 221 of the tubular metal jacket 201 is part of the second part U2 of the unheated area U of the electrical heating device 200. The second part U2 of the unheated area U is also produced in this example from a section of a feedthrough 220, whose outer metal jacket is used as a second part 221 of the tubular metal jacket 201 of the electrical heating device 200, wherein, in its interior, an internal conductor 222 is arranged, which is electrically insulated from the outer metal jacket of the feedthrough by an electrically insulating material 225. The internal conductor can be produced preferably from nickel or copper.

[0143] The feedthrough 220, which is also produced in this example from extruded or band material, was here cut differently than for the electrical heating device 100 to the length of this extruded or band material that corresponds to the desired length of the second part U2 of the unheated area. Furthermore, for the electrical heating device 200, holes 223,224 are formed in both end sides of the internal conductor 222, in which on the one end side, the section of the connection wire 213 projecting past the end side of the first part 211 of the tubular metal jacket 201 is formed and is used on the opposite side for forming the connection 226, which is simply inserted into the hole and, as shown in FIG. 13c, forms a press-fit contact and is fixed by a pressing or compression step. Here, the sequence in which these steps is performed is not important.

[0144] FIG. 13b shows a view of the longitudinal section from FIG. 13a after the joining of the first part 211 and the second part 221 of the tubular metal jacket 201. Here, the first part 211 and the second part 221 of the tubular metal jacket 201 were positioned against each other at the ends and welded or soldered at the connection point 231.

[0145] Preferably, on the electrical heating device 200, as shown in FIG. 13b, another processing step is performed, whose result is clear in FIG. 13c: another compression, which could also be realized as a local pressing or repeated compression step, is performed in the area of the second part 221 of the tubular metal jacket, preferably in the area, in which the hole 223 is located with the section of the connection wire 213 arranged therein, but at a distance from the connection point 231. This processing step can be executed concretely, for example, as a hexagonal crimping step, in particular, by hammering, and is associated with the advantages already discussed above.

[0146] FIGS. 14 to 17 show different intermediate states during the execution of another method for producing an electrical heating device 300.

[0147] The electrical heating device 300 differs from the previously discussed electrical heating devices 10,100 and 200 basically in that, here, the first part 311 of the tubular metal jacket 301 has no first unheated section U1 and, in particular, also no unheated transition section UE1. Thus, it forms the heated area with electrical heating element 312 formed by a coiled resistive wire and electrically insulating material 315 only over its total length in its interior.

[0148] For this construction, it is possible to freely select the length of the heated area, in that the coiled heating element is provided with electrically insulating material and the tubular metal jacket is provided as extruded material. From this material, a piece with a length that corresponds to the length of the desired heated area plus the length of the unheated transition sections is cut. Then, the tubular metal jacket and the surrounding electrically insulating material are cut with a mold 350 to the length corresponding to the respective unheated transition sections, so that a part of the coiled electrical heating element, which is used for forming the unheated transition area UE1, extends past the end sides, as shown in FIG. 14.

[0149] As can be seen in FIG. 15a, a connection wire 313 and a feedthrough 320, whose metal jacket forms the second part of the tubular metal jacket of the electrical heating device 300, is provided with internal conductor 322, hole 323, and electrically insulating material 325, which can be produced as explained above in connection with the electrical heating devices 100 and 200.

[0150] Then the connection wire 313 is inserted into the end-side section of the electrical heating element 312; this section of the electrical heating element 312 is inserted with inserted connection wire into the hole 323 of the internal conductor 322 and the first part 311 of the tubular metal jacket 301 is welded or soldered with the second part 321 of the tubular metal jacket 301 at the ends, which leads to the intermediate state shown in FIG. 16.

[0151] Another local compression process, e.g., by hammering in hexagonal crimping, is then performed in the unheated transition area UE1, whereby here, on one side, the homogenization of the electrically insulating material in the transition area between the first part 311 of the tubular metal jacket 301 and the second part 321 of the tubular metal jacket 301 can be realized and, on the other side, an intimate press-fit contact between electrical heating element 312, connection pin 313, and internal conductor 322 can be realized, as can also be seen in FIG. 17a.

[0152] In FIGS. 15b and 17b, the intermediate state corresponding to FIGS. 15a and 17a is shown in a second variant, respectively, which differ from the variants of FIGS. 15a and 17a only in that a stepped connection pin 313′ is used instead of the connection pin 313 and accordingly the hole 323 is replaced by a stepped hole 323′. The thinner section 313a′ of the stepped connection pin 313′ is here also subjected to a local compression process after it was inserted into the section 323a′ of the stepped hole 323′ and thus a press-fit contact is formed directly, while in the other section of the stepped connection pin 313′, a press-fit contact to the hole 323′ is realized only indirectly by means of the electrical heating element 312.

[0153] Because there are no other differences, the reference symbols from FIGS. 15a and 17a are still used, and for the description of the other aspects contained in FIGS. 15b and 17b, refer to the corresponding description in FIGS. 15a and 17a.

[0154] FIGS. 18 to 21 show different intermediate states during the execution of another method for producing an electrical heating device 400.

[0155] Just like for the electrical heating device 300, for the electrical heating devices 400, the first part 411 of the tubular metal jacket 401 has no first unheated section U1 and, in particular, also no unheated transition section UE1. Thus, the heated area is merely formed in its interior over its entire length with electrical heating element 412 formed here by a coiled resistive wire and electrically insulating material 415.

[0156] Like for the electrical heating device 300 and its production, the coiled heating element is provided with electrically insulating material and tubular metal jacket as extruded material and then cut on the end sides to the length of the tubular metal jacket corresponding to the respective unheated transition sections and the surrounding electrically insulating material with a mold 450, so that a part of the coiled electrical heating element, which is used for forming the unheated transition area UE1, extends past the end sides, as shown in FIG. 18.

[0157] As can be seen in FIG. 19, then a feedthrough 420, whose metal jacket forms the second part 421 of the tubular metal jacket 401 of the electrical heating device 400, is provided with internal conductor 422, on the end side in the annular groove 423 formed in the internal conductor 422 and electrically insulating material 425. Differently than in the corresponding step that is shown in FIG. 15, no separate connection wire is needed.

[0158] Then the end-side section of the electrical heating element 412 is inserted into the hole 423 of the internal conductor 422 and the first part 411 of the tubular metal jacket 401 is welded or soldered with the second part 421 of the tubular metal jacket 401 at the ends, which leads to the intermediate state shown in FIG. 20.

[0159] Another local compression process, e.g., by hammering in hexagonal crimping, is then performed in the unheated transition area UE1, by means of which, here, on one side, the homogenization of the electrically insulating material can be effected in the transition area between the first part 411 and the second part 421 of the tubular metal jacket and on the other side, an intimate press-fit contact can be realized between the electrical heating element 412 and internal conductor 422, as can also be seen in FIG. 21.

[0160] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

LIST OF REFERENCE SYMBOLS

[0161] 10, 100, 110, 200, 210, 300, 400 Electrical heating device [0162] 11, 101, 201, 301, 401 Multi-part tubular metal jacket [0163] 11.1, 111, 211, 311, 411 First part (of the metal jacket) [0164] 11.2, 121, 221, 321, 421 Second part (of the metal jacket) [0165] 12, 12′, 12″, 112, 212, 312, 412 Electrical heating element [0166] 12.1, 12.1″ Section [0167] 13, 113, 213, 313 Connection wire [0168] 313′ Stepped connection wire [0169] 313a′ Section [0170] 14 Connection sleeve [0171] 15 Connection pin [0172] 15.1 Opening [0173] 16, 115, 215, 315, 415 Electrically insulating material [0174] 17, 125, 225, 325, 425 Electrically insulating material [0175] 18 Plug [0176] 111a End area [0177] 113a Thread [0178] 121a End area [0179] 123a Counter thread [0180] 114, 214 Weld seam [0181] 120, 220, 320, 420 Feedthrough [0182] 122, 222, 322, 422 Internal conductor [0183] 123, 223, 224, 323 Hole [0184] 323′ Stepped hole [0185] 323a′ Section [0186] 131, 231, 331, 431 Connection point [0187] 132 Cavity [0188] 133 Ring [0189] 226 Connection [0190] 350, 450 Mold [0191] 423 Annular groove [0192] A Length (of a connection) [0193] B Heated area [0194] U Unheated area [0195] U1 First part (of the unheated area) [0196] U2 Second part (of the unheated area) [0197] UE1 Unheated transition area [0198] W1, W2 Coil axis