Electric heating device and method for manufacturing an electric heating device

Abstract

Electric heating device (100, 200, 300, 400, 700) with a tubular metal sheath (140, 240, 340, 440, 740) and an electric heating element (110, 210, 310, 410, 510, 610, 710) which is embedded in an electrically insulating material (130, 230, 330, 730) inside the tubular metal sheath (140, 240, 340, 440, 740) and is coiled at least in sections, wherein the electric heating element (100, 200, 300, 400, 700) has at least one unheated end region, wherein the unheated end region in turn has one or more formed coils (112, 212, 312, 412, 512, 612, 712) of the electric heating element (110, 210, 310, 410, 510, 610, 710) and at least one pipe section of a pipe (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material, and wherein the unheated end region has a filling opening (113, 213, 313, 413, 513, 613, 713) for the electrically insulating material (130, 230, 330, 730), characterized in that the pipe section of the pipe (120, 220, 320, 420,520, 620, 720) made of electrically conductive material is arranged on the outside of at least one formed helix (112, 212, 312, 412, 512, 612, 712) of the electrical heating element (110, 210, 310, 410, 510, 610, 710) such that the formed helix (112, 212, 312, 412, 512, 612, 712) is located inside the tube section of the tube (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material.

Description

[0001] Electric heaters for heating objects or media are widespread. Especially with electric heaters that operate at low voltages, such as the on-board voltage of a car in the automotive sector, high currents are used during operation.

[0002] In many applications, it is also desirable for the heated area of ​​the electric heating device to be as sharply defined as possible. To achieve this, terminal studs made of a material with a significantly lower resistivity than that of the material of the electric heating element, which is often designed as a coiled resistance wire, are typically used to maximize its cross-sectional area. Typically, these terminal studs are inserted into the coil interior at the end sections of the electric heating element, creating an electrically conductive connection between the components.

[0003] At the same time, in many cases, there is a need to construct the electric heating device as compactly as possible, which, in particular, results in a small distance between the tubular metal casing and the coils of the electric heating element. However, when used with terminal bolts, problems arise when filling the electrically insulating material into the interior of the tubular metal casing.Therefore, in such cases, the desired level of process reliability during production has not yet been achieved, with process reliability during filling on the one hand and process reliability during production of the electrically conductive connection on the other hand being unsatisfactory, and the effort to find a viable middle ground between the cross-sectional area of ​​the terminal bolt and the available filling gap can lead to the fact that at high currents in this embodiment the heating power at the terminal bolt can still be too high.

[0004] DE 14 65 025 C discloses an electric heating device having the features of the preamble of patent claim 1 and a method for producing such an electric heating device having the features of the preamble of patent claim 7.

[0005] The object of the invention is therefore to provide an electric heating device which can be produced with improved process reliability and to provide a more process-reliable method for producing such an electric heating device.

[0006] This object is achieved by an electric heating device having the features of patent claim 1 and a method having the features of patent claim 7. Advantageous developments of the invention are the subject of the respective dependent patent claims.

[0007] The electric heating device according to the invention has a tubular metal casing and an electric heating element which is arranged in the interior of the tubular metal casing embedded in an electrically insulating material and is coiled at least in sections.

[0008] Particularly preferred is an electric heating element formed from a resistance wire with a flat-band-shaped cross-section. It is advantageous if the flat-band material of the resistance wire has a width at least 3 times greater than its thickness; a factor of 5x is preferred, and a factor of 8x is particularly preferred. The thickness of the flat-band material is its smallest dimension, and the width is the second smallest dimension of the flat band or the flat-band-shaped cross-section of the resistance wire.

[0009] Essential to the invention is that the electric heating element has at least one unheated end region, wherein the unheated end region in turn has one or more formed coils of the electric heating element and at least one tube section of a tube made of electrically conductive material, preferably copper, mild steel, nickel-plated mild steel, or nickel, via which the connection for supplying the electric heating element with power can be established, and wherein the unheated end region has a filling opening for the electrically insulating material. Using a resistance wire with a flat-band-shaped cross-section, a particularly large-area electrical contact with the tube made of electrically conductive material can be realized.

[0010] The unheated end region of the electric heating element thus forms an unheated transition region of the electric heating device, in which, when the electric heating device is in operation, the electric current flows simultaneously through both the pipe section or the pipe made of electrically conductive material and the end section of the electric heating element that is electrically connected to it. In other words, the unheated transition region contains a section of the electric heating element and at least one section of the pipe, whereby these sections are technically connected in parallel rather than in series.

[0011] The filling opening allows direct filling of the coil interior defined by coiled sections of the electric heating element with electrically insulating powder or granules, e.g. magnesium oxide, during manufacture of the electric heating device. Previously, this material had to pass between coils of the electric heating element to reach this area, which posed problems for process-reliable filling, particularly with small coil spacing. To avoid misinterpretation, it should be noted that the filling opening is a structure present in the unheated end region of the electric heating element, defined by the formed coils and / or at least tube sections of the tube made of electrically conductive material, which can usually be filled with electrically insulating material in the finished electric heating device.

[0012] By forming the coil according to the invention, by means of a forming process that leads to a reduction in the coil's outer diameter, the distance to the tubular metal casing can be increased in the radial direction, which is important for reducing problems when filling with the electrically insulating material in the area between the outside of the electric heating element and the tubular metal casing. This is of particular relevance because, according to the invention, the tube section of the tube made of electrically conductive material is pushed onto the formed coil(s), which can significantly increase the available conductor cross-section compared to known solutions. However, even if the tube section of the tube made of electrically conductive material is pushed onto the formed coil(s), the forming process can significantly improve the filling behavior when filling with electrically insulating material.

[0013] The pipe section can also optionally be formed by a section of a connecting bolt that contains a through-hole for filling the electrically insulating material. However, it can also be advantageous if at least one section of a connecting bolt is inserted into a section of the pipe section made of electrically conductive material, which is penetrated by a filling opening for filling the electrically insulating material, as this further increases the available cable cross-section.

[0014] In general, it should be remembered at this point that a pipe does not always have to have a circular cross-section, but can also be rectangular, oval, star-shaped or asymmetrical.

[0015] In the case of a slip-on tube, it is particularly preferred if the outer diameter of the tube section made of electrically conductive material corresponds to the outer diameter of the unformed coils of the electric heating element. This particularly facilitates electrical insulation from the tubular metal casing, because one or more corresponding single-hole tubes can then be easily slipped on as molded parts—preferably porous, e.g., preferably made of C820.

[0016] It has proven particularly useful if the tube made of electrically conductive material and a flat strip material from which the electrical heating element is made are matched to one another in such a way that the wall thickness of the tube is at least 40% of the thickness of the flat strip material, preferably at least 60% and most preferably at least 80%.

[0017] The electric heating device is particularly efficient in production when the formed coils are formed together with the tube section of the tube made of electrically conductive material, especially when pressing on the tube section of the tube made of electrically conductive material when it is pushed on.

[0018] Using a coiled resistance wire with a flat strip profile makes the overall structure significantly more stable, and nothing sags in the vertical position. This also allows for much smaller coil spacing, as the coils do not sag and touch each other before and during filling. This not only accommodates a larger heating conductor cross-section, but also enables more optimal and larger-area heat conduction to the outer jacket, as the heat-dissipating surface of the heating conductor is optimally utilized and the coil spacing is very small (e.g., a maximum of 0.25% of the strip thickness, especially a maximum of 0.15% or even just 0.1% of the strip thickness), both of which have a positive effect on service life.

[0019] By pressing pipe sections with formed coils of end sections of the electric heating element, a robust assembly is created which cannot be moved out of position due to its own weight in the direction of extension of the electric heating device.

[0020] In addition, the high rigidity and strength of the heating coil with pressed-on tube sections at the ends makes automation much easier. Handling, gripping, and insertion processes are easier to grasp, grasp, position, and transport.

[0021] In addition, when using resistance wire with a flat strip profile, the coils cannot get caught when they are folded together during intermediate storage because the pitch between the coils is too small.

[0022] Strip heating coils with pressed-on tubes are excellently suited for separation, conveying, and feeding (e.g., through vibration), making them easy to integrate into an automated process. However, even in manual production, the inventive solution with pressed-on or pressed-in tubes proves to be significantly more reliable, faster, simpler, and more cost-effective.

[0023] The manufacturing advantages associated with such a design are very great, in addition to the accommodation of a large cross-section at the ends and the process-reliable filling through a channel or in a channel.

[0024] If several adjacent formed coils are formed in such a way that their coil spacing is reduced compared to the coil spacing between non-formed coils, this further increases the contact area with the tube and is maximized when they are short-circuited directly (not just via the tube). Furthermore, if they are short-circuited, the heating power generated in the connection area formed by the tube section made of electrically conductive material is further reduced.

[0025] The method according to the invention for producing an electric heating device with a tubular metal casing and an electric heating element which is arranged in the interior of the tubular metal casing embedded in an electrically insulating material and is coiled at least in sections, is characterized in that an unheated end region is produced by, on the one hand, forming one or more coils of the electric heating element and, on the other hand, bringing at least one tube section of a tube made of electrically conductive material into electrical contact with formed coils of the electric heating element, so that the unheated end region produced in this way has a filling opening for the electrically insulating material.

[0026] In the method, the invention provides that the tube section of the tube made of electrically conductive material is brought into electrical contact with deformed coils of the electrical heating element by deforming coils of a coiled section of the electrical heating element and the tube section of the tube made of electrically conductive material is pushed at least in sections onto the outside of this coiled section or inserted onto the inside of this coiled section.

[0027] In a preferred development of the method, the tube section of the tube made of electrically conductive material is pressed with the outside of the formed section of the electric heating element when it is pushed on or pressed with its inside when it is pushed in.

[0028] This preferably occurs outside the tubular metal casing and without the presence of any electrically insulating material. Both of these factors contribute significantly to improved controllability and process reliability.

[0029] The process sequence is made particularly efficient by the fact that when the pipe section of the pipe made of electrically conductive material is pressed onto the outside and / or inside of the end section of the electric heating element, the coils of the coiled section, onto which the pipe section of the pipe made of electrically conductive material is pushed and / or into which it is pushed, are deformed.

[0030] Preferably, the pressing step is carried out in such a way that after pressing, the outer diameter of the unheated end region thus produced is equal to the outer diameter of non-formed coils of the electrical heating element.

[0031] If the electric heating element is inserted into the tubular metal casing as a common assembly with the pipe sections of the pipe made of electrically conductive material pushed onto or inserted into it and preferably already pressed together, impairment of the electrically conductive connection between these components due to contamination with particles of the electrically insulating material can be avoided.

[0032] Preferably, the electrically insulating material, in particular magnesium oxide, is introduced into the interior of the tubular metal casing as at least one molded part, in particular a porous molded part, for example made of C820, and / or either as a powder or as granules. It is advantageous if at least one molded part is a tube made of electrically insulating material pushed onto the assembly comprising the electric heating element and the tube sections of the tube made of electrically conductive material pushed onto it or inserted into it, and / or if the powder or granules are introduced into the interior of the tubular metal casing through the coil interior of the coiled electric heating element.

[0033] In particular, a combination of both variants allows for very small winding pitches, which is preferably achieved with flat strip material as electrical resistance wire, where the windings do not collapse and touch each other before and during filling. This allows for a larger heating conductor cross-section and more optimal and larger-area heat conduction to the outer jacket, as the heat-dissipating surface of the heating conductor is optimally utilized and the winding pitches are very small, e.g., a maximum of 0.25% of the thickness of the flat strip material, in particular a maximum of 0.15% or even just 0.1% of this strip thickness.However, with such small winding pitches, the usual filling with electrically insulating material via an annular gap does not ensure proper penetration of the electrically insulating material into the coil interior any more than it does with pure filling from the inside, through a filling opening for the electrically insulating material in the unheated end region of the electrical heating element produced according to the invention.

[0034] If part of the electrical heating element and / or part of the tubular metal sheath and / or part of the electrically insulating material is cut off with a tool, the length of the unheated sections can be freely configured as desired.

[0035] The invention is explained in more detail below with reference to figures illustrating exemplary embodiments. It shows: Fig. 1: A longitudinal section through a first embodiment of an electric heating device, Fig. 2a: a first intermediate stage in the manufacture of an electric heating device, Fig. 2b: a second intermediate stage in the manufacture of an electric heating device, Fig. 2c: a third intermediate stage in the manufacture of an electric heating device, Fig. 2d: a detailed enlargement from Fig. 2c, Fig. 2e: a fourth intermediate stage in the manufacture of an electric heating device, Fig. 2f: a fifth intermediate stage in the manufacture of an electric heating device, Fig. 2g: a sixth intermediate stage in the manufacture of an electric heating device, Fig. 2h: the completed electric heater, Fig. 3a: a longitudinal section through another embodiment of an electric heating device, Fig. 3b: an open view of the electric heating device from Fig. 3a, Fig. 3c: a detailed enlargement from Fig. 3b, Fig. 4a: a longitudinal section through a partial representation of another embodiment of an electric heating device, Fig. 4b: an opened partial view of the electric heating device from Fig. 4a, Fig. 4c: a cross section through the embodiment of the electric heating device from Fig. 4a, Fig. 5a: the components of a first variant of an unheated end region not according to the invention, Fig. 5b: a first intermediate step in the production of the first variant of the unheated end region not according to the invention, Fig. 5c: the unheated end region according to the first variant not according to the invention, Fig. 6a: the components of a second variant of an unheated end area, Fig. 6b: a first intermediate step in the production of the second variant of the unheated end area, Fig. 6c: the unheated end area according to the second variant, Fig. 7a: a first perspective of an intermediate step in the production of a third variant of the unheated end area, Fig. 7b: a second perspective of the intermediate step in the production of the third variant of the unheated end area, Fig. 7c: a first view of a part of an electric heating device with an unheated end region according to the third variant of the unheated end region, and Fig. 7d: a second view of the part of the electric heating device with unheated end region of Fig. 7c.

[0036] Fig. 1 shows a longitudinal section through an electric heating device 100 with a tubular metal casing 140. In the interior of the tubular metal casing 140, an electric heating element 110 is arranged, which is coiled over its entire length and has undeformed coils 111 and deformed coils 112 and is electrically insulated from the tubular metal casing 140 by an electrically insulating, highly thermally conductive material 130, for example magnesium oxide.The power supply to the electrical heating element 110 is via tubes 120 made of electrically conductive material, preferably copper, mild steel, nickel-plated mild steel or nickel, which have a section 121 pushed onto the outside of at least one formed coil 112 of the electrical heating element 110 and are pressed there, so that an unheated end region of the electrical heating element 110 is created, which has a filling opening 113 and via which the power supply to the electrical heating element 110 is carried out in all embodiments.

[0037] The interior of the section of the tube 120 made of electrically conductive material adjacent to the section 121 pushed onto the outside of at least one formed coil 112 of the electric heating element 110 is filled with a connecting bolt 160 having a filling opening 161 designed as a bore extending lengthwise through the connecting bolt and adjoining the filling opening 113. The tubes 120 are passed through plugs 151, 152, which close the tubular metal casing 140 at each end, so that they can be connected to electrical supply lines. Due to the better conductivity of the tubes 120, the electrical heating element 110 is supplied with power primarily via these, although current can of course also flow through the formed coils 112 pressed onto them.

[0038] An embodiment of a manufacturing method for an electric heating device 200 will now be described with reference to Fig. 2a to 2h presented.

[0039] In Fig. Figure 2a shows an electric heating element 210 coiled over its entire length into coils 211, which is provided as a first intermediate stage in the manufacture of an electric heating device. This electric heating element 210, preferably made of a flat strip material, in particular a resistance wire with a flat strip-shaped cross-section, is preferably self-supporting, i.e., dimensionally stable without the influence of external forces, and can be produced, for example, by coiling a resistance wire with a round or flat profile, but can also be cut from a tube or machined from a bar stock.

[0040] Pipes 220, which are preferably made of a material with good electrical conductivity, such as copper, mild steel, nickel-plated mild steel or nickel, are now pushed onto this coiled electrical heating element - completely in the embodiment shown - which leads to the Fig. 2b. In principle, the tubes 220 can also be formed by sections of a connecting bolt into which a bore has been drilled.

[0041] In a subsequent process step, the tubes 220 made of electrically conductive material are pressed onto the outside of the coils onto which they are pushed, which is indicated by the arrows in Fig. 2d. The pressing pressure is chosen so high that formed coils 212 are created, which leads to the Fig. 2c, but only so high that a filling opening 213 remains. If the coils 212 formed by the deformation are short-circuited with each other, this is usually intentional, since as little heat as possible should be generated in the connection areas. However, as will be explained in more detail below, it is important that a continuous coil interior is maintained as a filling opening 213 if a filling opening 213 is not created in any other way, such as in the case of the Fig. 7a to 7d discussed embodiment.

[0042] How to be particularly good at detailing the Fig. 2d, it is preferred that after pressing, the outer diameter D2 of the tube 220 made of electrically conductive material corresponds to the original outer diameter D1 of the coils 211, i.e. undeformed coils, so that the assembly formed from the electric heating element 210 and tubes 220 by pressing has a substantially constant diameter.

[0043] For this reason, it is also preferred, particularly in cases where only a tube section of the tube 220 made of electrically conductive material is pressed onto the electric heating element, if the tube 220 is filled evenly during pressing, either by a section of the electric heating element 210 or, as in the embodiment of the electric heating device 100 shown above, by a connecting bolt pushed in until it stops against the end face of the electric heating element 110 there.

[0044] The fourth, in Fig. The intermediate stage shown in Figure 2e is produced by inserting the assembly, created by pressing together tubes 220 made of electrically conductive material and the electric heating element 210, into the interior of a provided tubular metal casing 240, closing this casing on one side with one of the plugs 251, 252, and filling it with electrically insulating material 230, e.g., a magnesium oxide powder or granulate, before it is then closed with the second plug 252, 251. The electrically insulating material 230 can also be provided entirely or partially as one or more preferably porous molded parts, for example, single-hole tubes or in rod form made of C820 MgO, which can significantly simplify, in particular, the filling of the electrically insulating material to be arranged between the outside of the electric heating element 210 and the tubular metal casing 240.

[0045] The fifth intermediate stage in the manufacture of an electric heating device, which Fig. 2f, is derived from the fourth intermediate study by condensing, which is indicated by the arrows in Fig. 2f is symbolized.

[0046] Fig. 2g shows a sixth intermediate stage in the manufacture of an electric heating device, which is achieved by using a tool 10 to radially cut off parts of the electric heating element 210, in particular those that protrude beyond the connection-side end face of the tubes 220 made of electrically conductive material as a consequence of elongation during pressing, and, if desired, also parts of the tubular metal casing 240 and the electrically insulating material 230. In this way, in particular, the length of the unheated end regions of the electric heating device 200, which are formed by the formed coils 212 with the sections of the tubes 220 made of electrically conductive material pressed therewith, can be adjusted.

[0047] This then leads to the finished electric heating device 200, which in Fig. 2h is shown.

[0048] Fig. 3a shows a longitudinal section through an electric heating device 300 with tubular metal casing 340, Fig. 3b the same electric heating device 300 in an opened view and Fig. 3c an enlarged detail from Fig. 3b, which shows the structure in particular detail.

[0049] As in the embodiment according to Fig. 1, in the interior of the tubular metal casing 340, there is arranged an electrical heating element 310 which is coiled over its entire length and has undeformed coils 311 and deformed coils 312, which is electrically insulated from the tubular metal casing 340 by electrically insulating, highly heat-conducting material.

[0050] The essential difference to the electric heating device 100 according to Fig. 1 is that here the electrically insulating material is introduced on the one hand as a molded part 331, more precisely a single-hole breakable tube, which preferably consists of porous electrically insulating material, e.g. C820, which is pushed onto the electrical heating element 310 and the tubes 320 made of electrically conductive material, and on the other hand as a powder or granulate sprinkled through the filling opening 313 into the coil interior of the coiled electrical heating element 310, which largely eliminates filling problems that can otherwise occur with small distances between the electrical heating element 310 and the tubular metal jacket 340.

[0051] The electrical heating element 310 is again supplied primarily via tubes 320 made of electrically conductive material, preferably copper, mild steel, nickel-plated mild steel, or nickel, which are completely slid onto the outside of formed coils 312 and pressed there, forming an unheated end region of the electrical heating element. The tubes 320 made of electrically conductive material are guided through plugs 351, 352, which close the tubular metal casing 340 at each end, so that they can be connected to electrical supply lines.

[0052] Fig. 4a shows a longitudinal section through one half of an electric heating device 400 with tubular metal casing 440, Fig. 4b the same half of the electric heating device 400 in an opened view and Fig. 4c shows a cross-section through such an electric heating device 400 in its unheated end region. The complete electric heating device 400 is obtained by adding a section mirrored on a plane perpendicular to the direction of travel of the electric heating device 400, which corresponds to the section shown.

[0053] The electrical heating device 400 corresponds in its construction largely to the embodiment according to Fig. 3a to 3c. In the interior of the tubular metal casing 440 there is arranged an electrical heating element 410 which is coiled over its entire length and has undeformed coils 411 and deformed coils 412 and is electrically insulated from the tubular metal casing 440 by electrically insulating, highly thermally conductive material, which in turn is in the form of a shaped part 431, preferably made of porous, electrically insulating material, e.g. C820, more precisely a single-hole breakable tube, which is pushed onto the electrical heating element 410 and the tube 420 made of highly electrically conductive material, and on the other hand is introduced as a powder or granulate 432 which is sprinkled through the filling opening 413 into the coil interior of the coiled electrical heating element, which largely eliminates filling problems which can otherwise occur when the distances between the electrical heating element 410 and the tubular metal casing 440 are small.

[0054] The power supply to the electric heating element 410 is again primarily provided via tubes 420 made of electrically conductive material, preferably copper, mild steel, nickel-plated mild steel, or nickel, which are completely slid onto the outside of formed coils 412 and pressed there. The tubes 420 made of electrically conductive material extend out of the tubular metal casing 440 at the end face so that they can be connected to electrical supply lines.

[0055] The difference to the electric heating device 300 is that in the electric heating device 400, when pressing the electric heating element 410 and the tube section of the tube 420 made of electrically conductive material, the pressing pressure was applied by four stamps, each perpendicular to the two adjacent stamps, so that an unheated end region with a square cross-section and a square filling opening 413 was created, as can be seen particularly well in the cross-sectional representation of the Fig. 4c recognizes.

[0056] The Fig. 5a to 5c show the components, an intermediate step in the production process, and the produced unheated end region of a coiled electric heating element 510 in a first variant. Here, the unheated end region is formed by completely inserting a tube 520 made of electrically highly conductive material into the coil interior of coils 511 of an end section of the electric heating element 510. Then, in a pressing process, these coils are deformed to create deformed coils 512. A press contact is then established, creating an unheated end region of the electric heating element 510 with a filling opening 513, and the tube 520 and the electric heating element 510 become an interconnected assembly.

[0057] The Fig. 6a to 6c show the components, an intermediate step in the production process, and the produced unheated end region of a coiled electric heating element 610 in a second variant. Here, the unheated end region is formed by a first tube 620 made of electrically conductive material and a second tube 621 made of electrically conductive material each being completely inserted onto or into coils 611 of an end section of the electric heating element 610. Then, in a pressing process in which these coils are deformed to create deformed coils 612, a press contact is made, creating an unheated end region of the electric heating element 610 with a filling opening 613.

[0058] In the embodiment of the electric heating device 700 with tubular metal casing 740, electric heating element 710, electrically conductive tube 720, electrically insulating material 730 and plug 750, which are in the Fig. 7a to 7d, a further variant of an unheated end region of the electrical heating element 710 is used, which is produced by pressing with a tube 720 made of electrically highly conductive material.

[0059] As can be seen in particular from the Fig. 7a and Fig. 7b, the electric heating element 710 with the tube 720 made of electrically highly conductive material pushed onto its end region is inserted into a die 1 and deformed in one direction with a punch 2 during pressing, so that formed coils 712 formed into a U-shape and short-circuited with one another are created and the tube 720 pressed with them receives a U-shaped cross-section.

[0060] The filling opening 713, which enables the central filling of the interior of the non-formed coils 711 of the electrical heating element 710 with electrically insulating powder or granules, for example magnesium oxide, is then formed by the interior of the U. List of reference symbols 1 die 2 stamps 10 tools 100,200,300,400,700 electric heater 110,210,310,410,510,610,710 electric heating element 111,211,311,411,511,611,711 undeformed coil 112,212,312,412,512,612,712 formed coil 113,213,313,413,513,613,713 filling opening 120,220,320,420,520,620,720 tube Section 121 130,230,330,730 electrically insulating material 140,240,340,440,740 tubular metal casing 151,152,251,252,351,352,750 plugs 160 connecting bolts 161 Filling opening 331,431 molded part 432 Powder or granules D1 outer diameter D2 Outer diameter of the pipe

Claims

[1] Electric heating device (100, 200, 300, 400, 700) with a tubular metal casing (140, 240, 340, 440, 740) and an electric heating element (110, 210, 310, 410, 510, 610, 710) which is arranged embedded in an electrically insulating material (130, 230, 330, 730) in the interior of the tubular metal casing (140, 240, 340, 440, 740) and is coiled at least in sections, wherein the electric heating element (100, 200, 300, 400, 700) has at least one unheated end region, wherein the unheated end region in turn has one or more formed coils (112, 212, 312, 412, 512, 612, 712) of the electric heating element (110, 210, 310, 410, 510, 610, 710) and at least one tube section of a tube (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material, and wherein the unheated end region has a filling opening (113, 213, 313, 413, 513, 613, 713) for the electrically insulating material (130, 230, 330, 730), characterized bythat the tube section of the tube (120,220,320,420,520,620,720) made of electrically conductive material is arranged on the outside of at least one formed coil (112,212,312,412,512, 612,712) of the electric heating element (110,210,310,410, 510,610,710) such that the formed coil (112,212,312,412,512,612,712) is located in the tube interior of the tube section of the tube (120,220,320,420,520,620,720) made of electrically conductive material. [2] Electric heating device (100,200,300,400,700) according to claim 1, characterized by that the tube section of the tube (120,220,320,420,520,620,720) made of electrically conductive material is arranged on the inside of at least one formed coil (112,212,312,412,512, 612, 712) of the electric heating element (110,210,310,410,510, 610,710) such that the formed coil (112,212,312,412,512,612,712) surrounds the tube section of the tube (120,220,320,420,520,620,720) made of electrically conductive material. [3] Electric heating device (100, 200, 300, 400, 700) according to one of claims 1 or 2, characterized by in that at least one section of a connecting bolt (160), through which a filling opening (161) passes, is inserted into a further section of the tube (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material. [4] Electric heating device (100,200,300,400,700) according to one of claims 1 to 3, characterized by that the outer diameter (D1) of the tube section of the tube (120,220, 320,420,520,620,720) made of electrically conductive material, which is pushed onto the outside of at least one deformed coil (112,212,312,412,512,612,712) of the electric heating element (110,210,310,410,510,610,710), corresponds to the outer diameter (D2) of the undeformed coils (111,211, 311,411,511,611,711) of the electric heating element (110,210,310,410,510,610,710). [5] Electric heating device (100, 200, 300, 400, 700) according to one of claims 1 to 4, characterized by that the formed coils (112,212,312,412,512,612,712) are formed together with the tube section of the tube (120,220,320,420,520,620, 720) from electrically conductive material. [6] Electric heating device (100, 200, 300, 400, 700) according to one of claims 1 to 5, characterized by that several adjacent coils are deformed in such a way that their winding distance from one another is reduced compared to the winding distance between undeformed coils (111,211,311,411,511, 611,711) or in such a way that they are directly short-circuited with one another. [7] Method for producing an electric heating device (100, 200, 300, 400, 700) with a tubular metal casing (140, 240, 340, 440, 740) and an electric heating element (110, 210, 310, 410, 510, 610, 710) which is arranged embedded in an electrically insulating material (130, 230, 330, 730) in the interior of the tubular metal casing (140, 240, 340, 440, 740) and is coiled at least in sections, wherein an unheated end region is produced by, on the one hand, forming one or more coils of the electric heating element (110, 210, 310, 410, 510, 610, 710) and, on the other hand, forming at least one tube section of a tube (120, 220,320,420,720) made of electrically conductive material is brought into electrical contact with formed coils (112,212,312, 412,512,612,712) of the electric heating element (110,210, 310,410,510,610,710), so that the thus produced unheated end region has a filling opening (113,213,313,413,513,613,713) for the electrically insulating material (130,230,330,730), characterized by that the tube section of the tube (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material is brought into electrical contact with formed coils (112, 212, 312, 412, 512, 612, 712) of the electrical heating element (110, 210, 310, 410, 510, 610, 710) by forming coils of a coiled section of the electrical heating element (110, 210, 310, 410, 510, 610, 710) and that before or after forming the tube section of the tube (120, 220, 320, 420, 520, 620, 720) made of electrically conductive material is at least partially pushed onto the outside of this coiled section or on the inside of this coiled section is inserted. [8] Method according to claim 7, characterized by that the pipe section of the pipe (120,220,320,420,520,620,720) made of electrically conductive material is pressed with the end section of the electric heating element (110,210,310,410,510,610,710). [9] Method according to claim 8, characterized bythat when the pipe section of the pipe (120,220,320,420, 520,620,720) made of electrically conductive material is pressed onto the end section of the electric heating element (110,210,310, 410,510,610,710), the deformation of the coils of the coiled section, onto which the pipe section of the pipe (120,220, 320,420,520,620,720) made of electrically conductive material is pushed and / or into which the pipe section of the pipe (120,220,320,420,520,620,720) made of electrically conductive material is pushed, is effected. [10] Method according to one of claims 8 or 9, characterized by that after pressing, the outer diameter (D2) of the produced unheated end region is equal to the outer diameter (D1) of undeformed coils (111,211,311,411,511,611,711) of the electric heating element (110,210,310,410,510,610,710). [11] Method according to one of claims 7 to 10, characterized bythat the electric heating element (110,210,310,410,510,610,710) with the pipe sections of the pipe (120,220,320,420,520,620,720) made of electrically conductive material pushed onto or into it is introduced as a common assembly into the tubular metal casing (140,240,340,440,740). [12] Method according to one of claims 7 to 11, characterized by that electrically insulating material is introduced into the interior of the tubular metal casing (140,240,340,440,740) as at least one shaped part (331,431) and / or either as a powder or as granules (432). [13] Method according to claim 12, characterized bythat the shaped part (331,431) is a tube made of electrically insulating material pushed onto the assembly consisting of the electric heating element (110,210,310,410,510,610,710) with the tube sections of the tube (120,220,320,420,520,620,720) made of electrically conductive material pushed onto it or pushed into it, and / or that the powder or granulate is introduced into the interior of the tubular metal casing through the coil interior of the coiled electric heating element (110,210,310,410,510,610,710). [14] Method according to one of claims 7 to 13, characterized by that a part of the electrical heating element (110,210,310,410,510,610, 710) and / or a part of the tubular metal casing (140,240,340,440,740) and / or a part of the electrically insulating material (130,230,330,730) is cut off with a tool (10).

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