Electric heating cartridge with temperature monitoring and electric heater with temperature monitoring

Abstract

Electric heating cartridge (100, 200, 300, 400, 500, 600, 700) with an outer metal casing (110, 210, 310, 410, 510, 610, 710) and with at least one electric heating element (120, 121, 220, 320, 420, 520, 620, 720) arranged in an interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal casing (110, 210, 310, 410, 510, 610, 710), wherein in the interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal casing (110, 210, 310, 410, 510, 610, 710) of the electric heating cartridge (100, 200, 300, 400, 500, 600, 700) at least one temperature monitoring means (130, 230, 330, 430, 530, 630, 730) is arranged, which is galvanically separated from the electric heating element (120, 121, 220, 320, 420, 520, 620, 720), wherein the temperature monitoring means (130, 230, 330, 430, 530, 630, 730) is at least one wire present in addition to the electric heating element (120, 121, 220, 320, 420, 520, 620, 720) or a tube present in addition to the electric heating element (120, 121, 220, 320, 420, 520, 620, 720),wherein the wire or the tube is made of a cold-conducting material, wherein the value of the temperature coefficient of the electrical resistance between 20 and 105°C for this cold-conducting material is greater than 800 ppm / K, particularly preferably greater than 4000 ppm / K, and wherein the wire or the tube is directly embedded in an electrically non-conductive filling material filling the remaining interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal casing (110, 210, 310, 410, 510, 610, 710), characterized in that the wire or the tube is made of a material whose resistance has a temperature coefficient whose value in the range between 20°C and 105°C is at least twice as high, particularly preferably at least five times as high, as the value of the temperature coefficient of the resistance of the existing electrical heating elements (120,121,220,320,420,520,620,720) in the range between 20°C and 105°C.,

Description

[0001] The invention relates to an electric heating cartridge with temperature monitoring according to the features of the preamble of patent claim 1.

[0002] Electric heating cartridges are a versatile type of electrical heating device in which an electric heating element, typically designed as a heating wire or resistance wire, is arranged within an outer casing. The casing is often, but not necessarily, formed by a tube, particularly a tube with a circular cross-section. In addition to heating cartridges with only one metal casing, this type also includes hollow cartridges that have a second, inner, often also tubular metal casing.

[0003] In many applications where such electric heating cartridges are used, it is important to monitor the function of the electric heating cartridge. This often depends on reaching or maintaining a temperature at one or more points on the electric heating cartridge within a specified temperature window. To make this possible, it is known from DE 20 2008 014 050 U1 and DE 20 2007 010 865 U1, for example, to arrange a temperature sensor or temperature probe or an integrated thermocouple inside the electric heating cartridge. This is usually pressure-sensitive, which must be taken into account when pressing or compacting the heating cartridge. In addition, this only achieves local temperature monitoring at one point, so that a temperature deviation occurring at another point can only be detected when it has an effect on the locally monitored point.

[0004] Electrical heating elements with a temperature-dependent resistance behavior are known, for example, from DE 203 21 257 U1, DE 92 17 718 U1 and DE 10 2009 029 251 B4, the latter document disclosing the features of the preamble of claim 1.

[0005] The object of the invention is therefore to provide an electric heating cartridge and an electric heater with such a heating cartridge, in which the above-mentioned disadvantages are avoided. This object is achieved by an electric heating cartridge with the features of patent claim 1 and an electric heater with the features of patent claim 10. Advantageous developments of the invention are the subject of the dependent claims.

[0006] An electric heating cartridge according to the invention, as is usual for heating cartridges, has an outer metal casing and at least one electric heating element arranged in an interior space of the outer metal casing. Furthermore, at least one temperature monitoring device, which is galvanically isolated from the electric heating element, is arranged in the interior space of the metal casing of the electric heating cartridge.

[0007] What is essential to the invention is that the means for temperature monitoring is at least one wire present in addition to the electrical heating element or one tube present in addition to the electrical heating element, wherein the wire or the tube is made of a cold-conducting material, wherein the value of the temperature coefficient of the electrical resistance between 20 and 105°C for this cold-conducting material is greater than 800 ppm / K, particularly preferably greater than 4000 ppm / K. Furthermore, according to the invention, the wire or the tube is directly embedded in an electrically non-conductive filler material filling the remaining interior of the outer metal jacket, which filler material can be designed in particular as MgO powder or MgO granulate.

[0008] With the invention, for example, the resistance of the wire or pipe or quantities that are correlated with the resistance, e.g., the current flowing at a given voltage or the voltage required to achieve a given current, can be measured and compared with reference values ​​to implement temperature monitoring. This comparison is preferably carried out automatically in control and / or monitoring electronics for the heating cartridge, preferably using data from a resistance characteristic stored in a memory of this control and / or monitoring electronics.

[0009] In addition to the greater robustness against pressure, which allows a compaction of the electric heating cartridge, the inventive design of the means for temperature monitoring is characterized not only by its extremely cost-effective realization but also by the fact that the heating cartridge can be soft-annealed to make it flexible after compaction, and in particular also by annealing under protective gas, oxidizing or stress-relieving, which is not the case, for example, when using known PT-100 temperature sensors as a means for temperature monitoring.

[0010] According to the invention, the wire or tube is made of a material whose resistance has a temperature coefficient whose value in the range between 20°C and 105°C is at least twice as high, particularly preferably at least five times as high, as the value of the temperature coefficient of the resistance of the existing electrical heating elements in the range between 20°C and 105°C. This means that sufficient accuracy of temperature monitoring can be ensured even with possible resistance tolerances resulting from compaction.

[0011] Implementing the temperature monitoring device in this way results in a temperature monitoring device in which the ambient temperature of each individual section of the wire or tube made of a thermistor or heat conductor contributes to the temperature monitoring result, unlike most previously known temperature monitoring devices that perform a local temperature measurement. This can result in a faster response of the temperature monitoring device, since a locally occurring temperature change due to a malfunction affects the nearest section of the wire or tube made of a thermistor or heat conductor relatively immediately, eliminating the need to wait until the malfunction manifests itself at the point locally monitored by a sensor or thermocouple.

[0012] Furthermore, in contrast to the use of temperature sensors, temperature probes, or thermocouples known from the prior art, a temperature monitoring means is obtained that is largely insensitive to pressure, the operating current or voltage of which is adjusted such that the temperature dependence of this resistance only insignificantly influences the heating output, while optimizing the compression of the electric heating cartridge without additional effort for mechanical protection of the temperature monitoring means. Accordingly, it is particularly preferred if the electric heating cartridge is compressed or pressed at least in sections, with at least one section of the wire or tube present as the temperature monitoring means running in at least one compressed or pressed section.

[0013] According to a preferred embodiment of the invention, the temperature monitoring means is designed as a tube made of a cold-conducting material or a hot-conducting material, and the electric heating element is arranged in the interior of this tube, so that the tube and electric heating element together form a coiled tubing cartridge, the casing of which represents the temperature monitoring means. For electric heating elements designed as heating wires or resistance wires, this implies that they are electrically insulated from the tube forming the temperature monitoring means, for example, by an insulating material filling, which can be realized, for example, with a powder or granulate of magnesium oxide.

[0014] In a particularly preferred embodiment of the invention, the wire or tube serving as a temperature monitoring means is coiled. This enables a first refinement of the invention in which the wire or tube serving as a temperature monitoring means is wound onto a common winding body together with at least one heating element, but galvanically isolated from it. This enables particularly simple production of an electric heating cartridge with a temperature monitoring means.

[0015] Alternatively or in addition to the above-described development of the invention, the wire or tube used as a temperature monitoring means can be coiled with different spiral pitches. As already mentioned above, in the inventive design of the temperature monitoring means, the ambient temperature of each individual section of the wire or tube made of cold-conducting or hot-conducting material contributes to the temperature monitoring result.With a low coil pitch in a given area of ​​the electric heating cartridge, the section of the wire or tube affected by a temperature change in this area is extended, resulting in increased sensitivity of the temperature monitoring device to temperature changes in this area. Conversely, high coil pitches can create areas with low sensitivity. Thus, by using different coil pitches in a temperature monitoring device according to the invention, its sensitivity can be varied in different sections of the electric heating cartridge and optimally adapted to the requirements of the application.

[0016] According to a further advantageous embodiment of the invention, the wire or tube serving as a temperature monitoring means is arranged radially within the coils of at least one coiled electrical heating element. At this position, any local malfunctions can be particularly well detected. This is particularly the case when the electrical heating element is wound on a winding body and when the wire or tube serving as a temperature monitoring means extends at least partially within a bore or opening of the winding body.

[0017] It has proven particularly useful for all embodiments of the invention in which the wire or tube serving as a temperature monitoring means is made of a cold-conducting material if the material of the electrical heating element is a chromium-nickel-containing alloy or a copper-nickel-containing alloy, and if the material of the wire or tube serving as a temperature monitoring means is a pure metal, in particular nickel, fine nickel, or superfine nickel. If there are several such temperature monitoring means, several different pure metals can optionally also be used.

[0018] The electric heater according to the invention comprises an electric heating cartridge with an outer metal casing and at least one electric heating element arranged in an interior space of the outer metal casing, in which at least one means for temperature monitoring is arranged in the interior space of the metal casing of the electric heating cartridge, which means is galvanically separated from the electric heating element and is designed as at least one wire present in addition to the electric heating element or a tube present in addition to the electric heating element.The wire or tube is made either from a cold-conducting material or from a hot-conducting material, wherein the temperature coefficient of electrical resistance between 20 and 105°C for this hot-conducting or cold-conducting material is greater than 800 ppm / K, particularly preferably greater than 4000 ppm / K if it is a cold-conducting material, and greater than 250 ppm / K, particularly preferably greater than 800 ppm / K, particularly most preferably greater than 4000 ppm / K if it is a hot-conducting material. Furthermore, the wire or tube is directly embedded in an electrically non-conductive filler material that fills the remaining interior space of the outer metal sheath.

[0019] Furthermore, the electric heater according to the invention has a power supply for supplying current to the at least one electric heating element and a device for determining the resistance of the wire or the tube provided as a temperature monitoring means and for assigning a temperature value to the determined resistance of the wire or the tube provided as a temperature monitoring means.

[0020] It is particularly preferred if the device for determining the resistance of the wire or the tube provided as a means for temperature monitoring and for assigning a temperature value to the determined resistance of the wire or the tube provided as a means for temperature monitoring is in signal communication with the power supply for energizing the at least one electrical heating element, so that the energization of the at least one electrical heating element can be changed depending on the temperature value assigned to the resistance value by the device for determining the resistance.

[0021] The invention is explained in more detail below with reference to figures showing exemplary embodiments. It shows: Fig. 1a: a first electric heating cartridge, Fig. 1b: a section through the electric heating cartridge from Fig. 1a in the direction parallel to its direction of extension, Fig. 2a: a second electric heating cartridge, Fig. 2b: a section through the electric heating cartridge from Fig. 2a in a direction parallel to its direction of extension, Fig. 3: a section through a third electric heating cartridge in a direction parallel to its direction of extension, Fig. 4a: a fourth electric heating cartridge, Fig. 4b: a section through the electric heating cartridge from Fig. 4a in a direction parallel to its direction of extension, Fig. 5a: a fifth electric heating cartridge, Fig. 5b: a section through the electric heating cartridge from Fig. 5a in a direction parallel to its direction of extension, Fig. 6a: a sixth electric heating cartridge, Fig. 6b: an exploded view of the electric heating cartridge from Fig. 6a, Fig. 6c: the electric heating element from Fig. 6a in unrolled state, Fig. 6d: a cross-section through the electric heating cartridge from Fig. 6a in the direction perpendicular to its direction of extension, Fig. 7a: a section through a third electric heating cartridge in a direction parallel to its direction of extension, Fig. 7b: a first detail enlargement from Fig. 7a, Fig. 7c: a second detail enlargement from Fig. 7a, and Fig. 8: an electric heater.

[0022] Fig. 1a shows a first electric heating cartridge 100 with a tubular metal casing 110 with an oval cross-section, in this example, which is closed at each end by end pieces 111, 112, each of which is penetrated by three connecting bolts 114-119. As the sectional view according to Fig. 1b shows, in the interior 140 of the metal casing 110, two electrical heating elements 120, 121, implemented as coiled heating wires, are arranged, preferably under mechanical tension, between the connecting bolts 114 and 115 or 118 and 119, while between the connecting bolts 116 and 117, preferably under mechanical tension, there is arranged a temperature monitoring means 130 in the form of a coiled wire made of a cold-conducting material or of a hot-conducting material, which is shown thinner than the electrical heating elements 120, 121 to clarify that it is not a third electrical heating element and that a different material forms the wire. However, here, as in all other figures, this should not be understood as an indication of a necessary difference with regard to the necessary dimensioning, in particular with regard to the cross-section.

[0023] For reasons of clarity, the insulating material which actually fills the interior 140 of the respective metal casing 110 and is preferably pressed and which can consist of MgO powder or granulate, for example, is not shown in this and all other figures.

[0024] Fig. 2a shows a second electric heating cartridge 200 with a tubular metal casing 210, in this example, with a substantially rectangular cross-section and rounded corners, which is closed on one side by a base 211. On the other side, four connecting bolts 214-217 lead into the interior 240 of the metal casing 210. As the sectional view according to Fig. 2b shows, in the interior 240 of the metal casing 210, an electrical heating element 220, which is implemented as a coiled heating wire and runs in an approximately U-shape through the interior 240 of the metal casing 210, is arranged between the connecting bolts 214 and 215, while between the connecting bolts 216 and 217, a means for temperature monitoring 230 in the form of a coiled wire, made of a cold-conducting material or of a hot-conducting material, is arranged, which is shown thinner than the electrical heating element 220 and also runs in an approximately U-shape to clarify that it is not a second electrical heating element and that a different material forms the wire.

[0025] In contrast to the Fig. 1a and Fig. 1b shown electrical heating cartridge 100 which can be connected on both sides, the electrical heating cartridge 200 according to Fig. 2a and Fig. 2b is a heating cartridge 200 that can be connected on one side; furthermore, the electric heating cartridges 100, 200 differ in terms of their cross-section.

[0026] The Fig. 3 shows a sectional view of an electric heating cartridge 300 with a tubular metal casing 310, end pieces 311, 312, an electric heating element 320 arranged in the interior 340 of the metal casing 310 as a coiled, preferably self-supporting heating wire, which is arranged between connecting bolts 314 and 315, and a temperature monitoring means 330 arranged in the interior 340 of the metal casing 310 in the form of a coiled wire made of a cold-conducting material or a hot-conducting material, the ends of which extend directly from the tubular metal casing 310 and are therefore not provided with connecting bolts. The special feature of the embodiment according to Fig. 3 is that the temperature monitoring means 330 is arranged coaxially within the coils of the electrical heating element 320, which enables a very high sensitivity and particularly rapid reaction of the temperature monitoring means 330 to a local failure of the electrical heating element 320.

[0027] At the Fig. 4a and Fig. In the fourth electric heating cartridge 400 shown in Figure 4b, the tubular metal casing 410 is cylindrical and closed by an integrally formed base 411 and an end piece 412. The electric heating element 420, arranged in the interior 440 of the tubular metal casing 410 and realized as a coiled heating wire wound on a winding body 450, has its ends 420a, 420b passed through the end piece 412. Also passed through the end piece 412 are the ends 430a, 430b of the temperature monitoring means 430, which here is realized in the form of a U-shaped coiled wire made of a cold-conducting material or a hot-conducting material, lying in a center plane of the winding body 450.

[0028] At the Fig. 5a and Fig. In the fifth electric heating cartridge 500 shown in Figure 5b, the tubular metal casing 510 is also cylindrical and closed by a base 511 and a closure piece 512, wherein the base 511 has a recess 511a as a positioning aid for a winding body 550. As with the electric heating cartridge 400 according to Fig. 4a,b, the electrical heating element 520, arranged in the interior 540 of the tubular metal casing 510 and implemented as a coiled heating wire wound onto a winding body 550, is guided with its ends 520a, 520b through the end piece 512. Also guided through the end piece 512 are the ends 530a, 530b of the temperature monitoring means 530, which here is implemented in the form of a U-shaped coiled wire made of a cold-conducting material or a hot-conducting material and lying in a central plane of the winding body 550. The sections 530c, 530d of the temperature monitoring means 530 forming the two legs of the U are guided through bores in the winding body and thus arranged radially within the turns or coils of the electrical heating element 520 wound onto the winding body 550.

[0029] The Fig. 6a to 6d show a sixth embodiment of an electric heating cartridge 100. As can be seen particularly well in the exploded view of the Fig. 6b, the electric heating cartridge 600 comprises an electric heating element 620 arranged between an outer metal casing 610 and an inner metal casing 660, which are connected by means of a Fig. 6a are connected to each other by a floor surface 661 facing away from the viewer and therefore not visible. As in Fig. 6a, the electrical heating element 620 is arranged in the interior 640 of the outer metal casing 610 between an outer ceramic molded part 670, which at the same time ensures electrical insulation from the outer metal casing 610, and a middle ceramic molded part 671 and optionally additionally embedded in a not shown electrically insulating material, e.g. MgO granulate, which, however, is embedded in the Fig. 6a to 6c are not shown for reasons of clarity.

[0030] Additionally, between the central ceramic molded part 671 and an inner ceramic molded part 672, there is a temperature monitoring means 630, which is realized in the form of a wire made of a cold-conducting material or a hot-conducting material, wherein the wire also describes a spatial curve that can be obtained by rolling a meandering basic shape. It is preferred if the spatial curve described by the temperature monitoring means 630 can be converted into the spatial curve described by the electrical heating element 620 by scaling in the radial direction. Furthermore, it is preferred if an alignment is present in which corresponding points in the same direction of curved arcs 628, 629 and 638, 639 of the meander structures of the temperature monitoring means 630 and the electrical heating element 620 each lie on a common radius r, as is shown by way of example in Fig. 6d. In this way, each section of the electrical heating element 620 is directly associated with a section of the temperature monitoring means 630, which leads to particularly reliable detection of temperature deviations.

[0031] The Fig. The end face of the electric heating cartridge 600, visible to the observer in Figure 6a, is closed in the assembled state with a circular cover 662. The outer metal casing 610 and the inner metal casing 660 are each designed as a cylindrical tube and arranged concentrically to one another. The direction of extension of the outer metal casing 610 and the inner metal casing 660, respectively, is thus determined by the cylinder axis.

[0032] How to Fig. As can be seen particularly clearly in Figure 6c, which shows the electric heating element 620 in its unrolled or unrolled state, i.e. not in the state in which it is installed, the electric heating element has a meandering shape with meander loops. At each end of the electric heating element 620, a connecting bolt 614, 615 is provided with a Fig. 6c not visible bore, into which an end section of the electrical heating element 620 is received and electrically contacted.

[0033] In the Fig. 7a to 7c is shown as particularly well in the detailed representation of the Fig. As can be seen in Figure 7b, the electrical heating element 720 in the form of a heating wire is arranged centrally inside a temperature monitoring means 730, which is realized as a tube made of a cold-conducting material or a hot-conducting material, and is electrically insulated from this by magnesium oxide powder 735. Thus, the electrical heating element 720 and the temperature monitoring means together form a coiled tubing cartridge, which is arranged in sections coiled in the interior 740 of a cup-shaped outer metal casing 710. The filling of this interior space, which ensures heat conduction to the cup-shaped metal casing 710 and is made of a highly thermally conductive, preferably electrically non-conductive material, in particular MgO powder or granulate, has been omitted for reasons of clarity. Contact plates 713, 714 and connecting bolts 721, 722 are provided for contacting the electrical heating element 720.The temperature monitoring means 730 is contacted via contact plates 715,716 and connecting wires 717,718, as particularly well shown in . Fig. 7c can be seen.

[0034] The Fig. The electric heater 1000 shown in Figure 8 comprises, in addition to an electric heating cartridge 200, as already described above with reference to the Fig. 2a,b and which is therefore in Fig. 8 with the same reference numerals as in Fig.2a,b, a power supply 1010 for energizing the at least one electrical heating element 220 and a device for determining the resistance 1020 of the wire present as a temperature monitoring means 230 and for assigning a temperature value to the determined resistance of the temperature monitoring means 230, which in this example are both combined in a controller 1030. Accordingly, the power supply 1010 and the electrical heating element 220 are connected to one another by electrical lines 1011, 1012 via the connecting bolts 214, 215, and the device for determining the resistance 1020 and the temperature monitoring means 230 are connected to one another by electrical lines 1021, 1022 via the connecting bolts 216, 217.

[0035] In addition, the device for determining the resistance 1020 of the temperature monitoring means 230 is in signal communication with the power supply 1010 via a signal line 1023, so that the current supply to the at least one electrical heating element 220 can be changed depending on the temperature value assigned to the resistance value by the device for determining the resistance 1020. List of reference symbols 100,200,300,400,500, 600,700 electric heating cartridge 110,210,310,410,510, 610,710 outer metal jacket 111,112,311,312,412, 512 end pieces 114,115,116,117,118, 119,214,215,216,217, 314,315,721,722 connecting bolts 120,121,220,320,420, 520,620,720 electric heating element 130,230,330,430,530, 630,730 Temperature monitoring devices 140,240,340,440,540, 640,740 interior 211,411,511 soil 420a,420b,520a,520b End 430a,430b,530a,530b End 450,550 winding bodies 511a Deepening Section 530c, 530d 628,629 sheets 638,639 sheets 660 inner metal jacket 661 floor area 670 outer ceramic molding 671 medium ceramic molding 672 inner ceramic molding 713,714,715,716 contact plate 717,718 connecting wire 735 Magnesium oxide powder 1000 electric heater 1010 Power supply 1011,1012,1021,1022 electrical cable 1020 Device for determining resistance 1023 Signal line 1030 Control r radius

Claims

[1] Electric heating cartridge (100, 200, 300, 400, 500, 600, 700) with an outer metal casing (110, 210, 310, 410, 510, 610, 710) and with at least one electric heating element (120, 121, 220, 320, 420, 520, 620, 720) arranged in an interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal casing (110, 210, 310, 410, 510, 610, 710), wherein in the interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal casing (110,210,310,410,510,610,710) of the electric heating cartridge (100,200,300,400,500,600,700) at least one means for temperature monitoring (130,230,330,430,530,630,730) is arranged, which is galvanically separated from the electric heating element (120,121,220,320,420,520,620,720), wherein the means for temperature monitoring (130,230,330,430,530,630, 730) comprises at least one wire present in addition to the electric heating element (120,121,220,320,420,520,620,720) or an additional wire present in addition to the electric heating element (120,121,220,320,420,520,620,720) existing pipe,wherein the wire or tube is made of a cold-conducting material, wherein the temperature coefficient of electrical resistance between 20 and 105°C for this cold-conducting material is greater than 800 ppm / K, particularly preferably greater than 4000 ppm / K, and wherein the wire or tube is directly embedded in an electrically non-conductive filling material filling the remaining interior space (140, 240, 340, 440, 540, 640, 740) of the outer metal jacket (110, 210, 310, 410, 510, 610, 710), characterized by that the wire or the tube is made of a material whose resistance has a temperature coefficient whose value in the range between 20°C and 105°C is at least twice as high, particularly preferably at least five times as high, as the value of the temperature coefficient of the resistance of the existing electrical heating elements (120, 121, 220, 320, 420, 520, 620, 720) in the range between 20°C and 105°C. [2] Electric heating cartridge (100, 200, 300, 400, 500, 600, 700) according to one of claims 1, characterized in that the electric heating cartridge (100, 200, 300, 400, 500, 600, 700) is compressed or pressed at least in sections, wherein in at least one compressed or pressed section at least a section of the wire present as a means for temperature monitoring (130, 230, 330, 430, 530, 630) or of the tube present as a means for temperature monitoring (730) runs. [3] Electric heating cartridge (700) according to any preceding claim, characterized by that the temperature monitoring means (730) is designed as a tube made of a cold-conducting material and that the electrical heating element (720) is arranged in the interior (740) of this tube, so that the tube forming the temperature monitoring means (730) and the electrical heating element (720) together form a coiled tubing cartridge. [4] Electric heating cartridge (100,200,300,400,500,700) according to any preceding claim, characterized by that the wire present as a means for temperature monitoring (130,230,330,430,530) or the tube present as a means for temperature monitoring (730) is coiled. [5] Electric heating cartridge (400,500) according to claim 3, characterized in that the wire present as a means for temperature monitoring (430,530) or the tube present as a means for temperature monitoring is wound together with the at least one electric heating element (420,520) on a common winding body (450,550). [6] Electric heating cartridge (100, 200, 300, 400, 500, 700) according to claim 3 or 4, characterized by that the wire provided as a means for temperature monitoring (130,230,330,430,530) or the tube provided as a means for temperature monitoring (730) is coiled with different coil pitches. [7] Electric heating cartridge (300,500) according to claim 1, characterized by that the wire or tube provided as a temperature monitoring means (330,530) is arranged radially within the coils of at least one coiled electrical heating element (320,520). [8] Electric heating cartridge (500) according to claim 6, characterized by that the electrical heating element (520) is wound on a winding body (550) and that the wire present as a means for temperature monitoring (530) or the tube present as a means for temperature monitoring runs at least in sections in a bore or opening of the winding body (550). [9] Electric heating cartridge (100,200,300,400,500,600,700) according to claim 1, characterized bythat the material of the electric heating element (120,121,220,320,420, 520,620,720) is a chromium and nickel-containing alloy or a copper and nickel-containing alloy and that the material of the wire present as a means for temperature monitoring (130,230,330,430,530,630) or the tube present as a means for temperature monitoring (730) is a pure metal, in particular nickel, fine nickel or extra fine nickel. [10] Electric heater (1000) with an electric heating cartridge (100, 200, 300, 400, 500, 600, 700) according to one of the preceding claims, with a power supply (1010) for energizing the at least one electric heating element (120, 121, 220, 320, 420, 520, 620, 720) and with a device for determining the resistance (1020) of the wire present as the temperature monitoring means (130, 230, 330, 430, 530, 630) or of the tube present as the temperature monitoring means (730) and for assigning a temperature value to the determined resistance of the wire present as the temperature monitoring means (130, 230, 330, 430, 530, 630) or of the tube present as the temperature monitoring means (730). [11] Electric heater (1000) according to claim 10, characterized bythat the device for determining the resistance (1020) of the wire present as a means for temperature monitoring (130, 230, 330, 430, 530, 630) or of the tube present as a means for temperature monitoring (730) and for assigning a temperature value to the determined resistance of the wire present as a means for temperature monitoring (130, 230, 330, 430, 530, 630) or of the tube present as a means for temperature monitoring (730) is in signal communication with the power supply (1010) for energizing the at least one electrical heating element (120, 121, 220, 320, 420, 520, 620, 720), so that the energization of the at least one electrical heating element (120, 121, 220, 320, 420, 520, 620, 720) is dependent on the resistance determined by the device for determining the resistance (1020) the temperature value associated with the resistance value can be changed.

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