Heating cartridge with temperature sensor

Abstract

Heating cartridge (100, 200, 300) with a tubular metal jacket (110, 210, 310), in the interior of which an electric heating element (121, 221, 321) wound on a coiled body (120, 220, 320) is electrically insulated from the tubular metal jacket (110, 210, 310) by being embedded in an electrically non-conductive insulating material, and at least one temperature sensor (130, 230, 330, 335) with leads (131, 132, 231, 232, 331, 332, 336, 337) are arranged, wherein at least one lead (131, 132, 231, 232, 331, 332, 336, 337), preferably both leads (131, 132, 231, 232, 331, 332, 336, 337) at least one temperature sensor (130, 230, 330, 335) runs between the winding body (120, 220, 320) and the tubular metal sheath (110, 210, 310) and is electrically insulated from the winding body (120, 220, 320) and the heating element (121, 221, 321) wound on it as well as from the tubular metal sheath (110, 210, 310), characterized in that the winding body (120, 220,320) with the electrical heating element (121, 221, 321) wound on it and / or at least one supply line (131, 132, 231, 232, 331, 332, 336, 337) of the temperature sensor (130, 230, 330, 335), are received in recesses or bores (141, 142, 143, 241, 242, 243, 261, 262, 263, 341, 342, 343, 344, 345) of an insulating body (140, 240, 260, 340).

Description

[0001] The invention relates to a heating cartridge with a temperature sensor having the features of the preamble of claim 1.

[0002] In applications where ensuring a specific heating output and / or temperature is crucial, heating cartridges equipped with a temperature sensor or thermocouple are often used. Based on the measurement data from this temperature sensor or thermocouple, the electrical operating conditions, such as the operating current and / or voltage, can then be adjusted. In the following text, the term "temperature sensor" is used to include thermocouples.

[0003] In practice, the temperature ranges tolerated by users are becoming increasingly narrow, and the required times for deviations to be compensated for are becoming ever shorter. This leads, on the one hand, to increased demands on the precision of temperature measurement and, on the other hand, to electrical operating conditions being subject to increasingly frequent changes. In the applicant's operation, it was observed that with known heating cartridges, these two requirements negatively influence each other, because changes in operating conditions lead to disturbances in the temperature signal, and these disturbances in the temperature signal lead to more frequent changes in operating conditions.

[0004] Such electric heating cartridges are known, for example, from DE 20 2015 104 723 U1 and CN 2 02 035 159 U. In particular, the former of these documents discloses an electric heating cartridge with the features of the preamble of claim 1.

[0005] The object of the invention is therefore to provide an improved heating cartridge with temperature sensor in which, in particular, this interaction between changes in operating conditions and disturbances of the temperature signal is reduced.

[0006] This problem is solved by a heating cartridge with the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] The heating cartridge according to the invention has a tubular metal jacket in the interior of which an electrical heating element—e.g., a heating wire—wound onto a coiled body is electrically insulated from the tubular metal jacket by being embedded in an electrically non-conductive insulating material. At least one temperature sensor with connecting leads is also arranged within this jacket. It is explicitly noted that the thermocouple legs are also to be understood as connecting leads within the meaning of this description. Furthermore, for the sake of clarity, it is explicitly mentioned that a tubular metal jacket may, but does not necessarily have to, have a base.

[0008] The essential feature of the invention is that at least one supply line of at least one temperature sensor runs in the space between the winding body and the tubular metal sheath (and no longer, as in the prior art, inside the winding body) and is electrically insulated from the winding body and the heating element wound on it as well as from the tubular metal sheath.

[0009] The inventor has determined that this measure significantly reduces the negative impact of changes in operating conditions on the temperature sensor signals. The advantage is particularly great when all temperature sensor leads are routed in this way.

[0010] In order to achieve a well-defined position of the leads relative to the metal sheath, but also relative to the winding body and the heating element wound on it, the winding body with the electrical heating element wound on it and / or the lead of the temperature sensor is received in recesses or bores of an insulating body according to the invention.

[0011] It is particularly preferred if the recesses or bores run parallel to the axis of the tubular metal shell, i.e., in the case of cylindrical tubular metal shells, parallel to the cylinder axis.

[0012] Preferably, the heating cartridge is compressed.

[0013] It is particularly advantageous if the insulating body is impregnated with a silicone-containing substance, e.g., resin or oil.

[0014] Ceramic molded bodies are particularly well suited as insulating bodies.

[0015] Even more reliable electrical insulation can be ensured if the volumes remaining between the wound coil body and the insulating body, and between the tubular metal sheath and the insulating body, are at least partially filled with MgO granules, which in a preferred embodiment are also impregnated, in particular by the addition of powdered silicone resin.

[0016] To further eliminate any remaining empty volumes that hinder good heat distribution across the internal volume of the heating cartridge and onto the metal jacket, it helps if the heating cartridge is at least partially compacted.

[0017] It is particularly preferred if an electrical connection is made in the recesses or bores where the supply leads are arranged, to connecting wires inserted into these recesses or bores. In this way, the necessary connection is located where it is protected from mechanical stress by the heating cartridge. This connection can be made, for example, by crimping, but it is even more advantageous if the molded body has windows that expose the supply leads and connecting wires at the points where the electrical connections are made. The electrical connections can then be defined at these points and made with the possibility of visual inspection, e.g., by welding, soldering, or, if necessary, crimping.

[0018] If the heating cartridge is to be very compact, it is advantageous if two leads of the same temperature sensor lie in the same plane as the winding body and are arranged on different sides of the winding body.

[0019] In contrast, the preferred arrangement of the winding body and leads within the metal sheath when two temperature sensors are provided is that the leads of one temperature sensor are located above a plane in which the winding body is located, and the leads of the other temperature sensor are located below a plane in which the winding body is located.

[0020] It has proven advantageous if at least three connecting wires (including connecting leads) are provided for contacting the leads of the temperature sensor and the electrical heating element, of which at least one runs at least partially through the winding body and at least two run outside the winding body. Preferably, the connecting wires for contacting the electrical heating element run inside the winding body, and the connecting wires for contacting the leads of the temperature sensor run outside the winding body.

[0021] It is also preferred if the connecting wires for contacting the temperature sensor leads and the temperature sensor leads themselves are inserted into the insulating body from different sides. This avoids the need to thread the entire, potentially very long, connecting cable, for example, through openings in the insulating material.

[0022] If the insulating body has openings or recesses for filling with MgO powder or granules, any empty volumes can be electrically insulated after the insulating body has been inserted during manufacturing.

[0023] It is further preferred if a press contact is made between the connecting wires for contacting the temperature sensor leads and the leads of the temperature sensor, and / or if a press contact is made between the connecting wires for contacting the electrical heating element and the electrical heating element itself. This type of contact can be easily created when sealing the heating cartridge after assembly.

[0024] The invention is explained in more detail below with reference to figures showing exemplary embodiments. These show: Fig. 1a: an exploded view of a first embodiment, Fig. 1b: a sectional view of the exemplary embodiment from Fig. 1a, Fig. 2a: an exploded view of a second embodiment, Fig. 2b: a sectional view of the exemplary embodiment from Fig. 2a, Fig. 3a: an exploded view of the internal structure of a variant of the second embodiment, Fig. 3b: the internal structure made of Fig. 3a in compound state, Fig. 3c: a close-up from Fig. 3b, Fig. 4a: a partial exploded view of a third embodiment, and Fig. 4b: a sectional view of the exemplary embodiment from Fig. 4a.

[0025] Fig. Figure 1a shows an embodiment of a heating cartridge 100 with a tubular metal jacket 110 with in Fig. 1b recognizable base 111, winding body 120 with heating element 121 wound on it in the form of a heating wire, temperature sensor 130 with supply lines 131,132 and connecting wires 133, 134 as well as an insulating body 140 with bores 141,142,143, which is designed as a ceramic molded body.

[0026] How to excel at Fig. As can be seen from Figure 1b, the winding body 120 with the heating element wound on it is received in its own bore 141 of the insulating body 140, which is located centrally within it, while the leads 131, 132 of the temperature sensor 130, which are electrically contacted with the connecting wires 133, 134 in a press contact, are guided in the bores 142, 143. Since these bores are located radially further outwards in the insulating body 140, the leads 131, 132 are also located between the winding body and the tubular metal sheath 110.

[0027] The remaining internal volume of the tubular metal casing 110 is filled with MgO granules 150.

[0028] In particular, leads 131, 132 of the same temperature sensor, namely of temperature sensor 130, lie in a plane in which the winding body 120 also lies and are on different sides of the winding body 120, namely in the representation of the Fig. 1b arranged once above the winding body 120 and once below the winding body 120.

[0029] The embodiment described in the Fig. 2a and Fig. Figure 2b shows a heating cartridge 200 with a tubular metal jacket 210 with in Fig. 2b recognizable base 211, winding body 220 with heating element 221 wound on it in the form of a heating wire, temperature sensor 230 with supply lines 231,232 and connecting wires 233, 234 as well as an insulating body 240 with bores 241,242,243, which is designed as a ceramic molded body.

[0030] The difference to the exemplary embodiment of the Fig. 1a and Fig. 1b consists in the arrangement of the bores 242,243, which here are both located above the central bore 241, into which the winding body 220 with the heating element 221 wound on it is inserted.

[0031] The in the Fig. The variant of the heating cartridge 200 shown in Figures 3a to 3c differs only in that it uses a modified insulating body 260 instead of the insulating body 240; otherwise, the same reference numerals are used. In addition to the bores 261, 262, 263, which are arranged exactly as in the insulating body 240, the insulating body 260 also has a window 264 that locally exposes the supply lines 231, 232 and connecting wires 233, 234, thus enabling contact between the supply lines 231, 232 and the associated connecting wires 233, 234 as in Figure 3a. Fig. 3c is shown in detail by welding points 235,236, which are defined and can be produced and verified in a process-reliable manner.

[0032] The embodiment described in the Fig. 4a and Fig. As shown in 4b, a heating cartridge 300 with a tubular metal jacket 310 is included. Fig. 4b recognizable base 311, winding body 320 with heating element 321 wound on it in the form of a heating wire, temperature sensor 330 with supply lines 331,332 and connecting wires 333, 334 as well as an insulating body 340 with bores 341,342,343, which is designed as a ceramic molded body.

[0033] The difference to the exemplary embodiment of the Fig. 2a and Fig. 2b consists in the provision of a second temperature sensor 335 with supply lines 336,337 and connecting wires 338,339 and in the provision of two additional bores 344,345 in the insulating body 340 in which the supply lines 336,337 are brought into contact with the connecting wires 338,339 and crimped. Reference symbol list 100, 200, 300 Heating cartridge 110, 210, 310 Metal casing 111,211,311 Floor 120, 220, 320 winding bodies 121,221,321 Heating element 130, 230, 330, 335 Temperature sensor 131, 132, 231, 232, 331, 332, 336, 337 Supply lines 133, 134, 233, 234, 333, 334, 338, 339 connecting wires 140, 240, 260, 340 Insulating bodies 141, 142, 143, 241, 242, 243, 261, 262, 263, 341, 342, 343, 344, 345 bore 150, 250, 350 MgO granules 235,236 Welding point 264 windows

Claims

[1] Heating cartridge (100, 200, 300) with a tubular metal jacket (110, 210, 310) in the interior of which an electric heating element (121, 221, 321) wound on a coiled body (120, 220, 320) is electrically insulated from the tubular metal jacket (110, 210, 310) by being embedded in an electrically non-conductive insulating material, and at least one temperature sensor (130, 230, 330, 335) with leads (131, 132, 231, 232, 331, 332, 336, 337) are arranged, wherein at least one lead (131, 132, 231, 232, 331, 332, 336, 337), preferably both leads (131,132,231,232,331,332,336, 337) of at least one temperature sensor (130,230,330,335) runs between the winding body (120,220,320) and the tubular metal sheath (110,210,310) and is electrically insulated from the winding body (120,220,320) and the heating element (121,221,321) wound on it, as well as from the tubular metal sheath (110,210,310), characterized by, that the winding body (120,220,320) with the electrical heating element (121,221,321) wound on it and / or at least one supply line (131,132,231,232,331,332,336,337) of the temperature sensor (130,230,330,335) are received in recesses or bores (141,142,143,241,242,243,261,262,263,341,342,343,344,345) of an insulating body (140,240,260,340). [2] Heating cartridge (100, 200, 300) according to claim 1, characterized by , that the recesses or bores (141,142,143,241,242,243,261,262, 263,341,342,343,344, 345) run parallel to the axis of the tubular metal shell (110,210,310). [3] Heating cartridge (100, 200, 300) according to claim 1 or 2, characterized by that the structure is dense. [4] Heating cartridge (100, 200, 300) according to one of claims 1 to 3, characterized by , that the insulating body (140,240,260,340) is a ceramic molded body. [5] Heating cartridge (100, 200, 300) according to one of claims 1 to 4, characterized by, that the volumes remaining between the wound coil body (120,220,320) and the insulating body (140,240,260,340) and between the tubular metal sheath (110,210,310) and the insulating body (140,240,260,340) are at least partially filled with MgO granules (150,250,350). [6] Heating cartridge (100, 200, 300) according to one of claims 2 to 5, characterized by , that in the recesses or bores (141,142,143,241,242,243,261, 262,263,341,342,343,344,345) in which the supply lines (131,132,231,232,331,332,336,337) are arranged, an electrical connection is made to connecting wires (133,134,233,234,338,339) inserted into these recesses or bores (141,142,143,241,242,243,261,262,263,341,342,343,344,345). [7] Heating cartridge (200) according to claim 6, characterized by, that the shaped body (260) has at least one window (264) which exposes the supply lines (231,232) and connecting wires (233,234) at points where electrical connections are made. [8] Heating cartridge (100) according to any one of the preceding claims, characterized by , that two leads (131,132) of the same temperature sensor (130) lie in a plane in which the winding body (120) also lies and are arranged on different sides of the winding body (120). [9] Heating cartridge (300) according to any one of the preceding claims, characterized by , that two temperature sensors (330,335) are present, wherein the leads (331,332) of one temperature sensor (330) are located above a plane in which the winding body (320) is located and the leads of the other temperature sensor (336,337) are located below a plane in which the winding body (320) is located. [10] Heating cartridge (100, 200, 300) according to any of the preceding claims, characterized by, that at least 3 connecting wires (133,134,233,234,333,334,338,339) are available for contacting the leads of the temperature sensor (130,230,330,335) and for contacting the electrical heating element (121,221,321), of which at least one runs at least partially through the winding body (120,220,320) and of which at least two run outside the winding body (120,220,320). [11] Heating cartridge (100, 200, 300) according to claim 10, characterized by , that the connecting wires for contacting the electrical heating element (121,221,321) run through the winding body (120,220,320) and that the connecting wires (133,134,233,234,333,334,338,339) for contacting the leads (131, 132,231,232,331,332,336,337) of the temperature sensor (130, 230,330,335) run outside the winding body (120,220, 320). [12] Heating cartridge (100, 200, 300) according to any one of claims 1 to 11, characterized by, that the connecting wires (133,134,233,234,333,334,338,339) for contacting the leads (131,132,231,232,331,332,336, 337) of the temperature sensor (130,230, 330,335) and the leads (131,132,231,232,331,332,336, 337) of the temperature sensor (130,230,330,335) are inserted into the insulating body from different sides. [13] Heating cartridge (100, 200, 300) according to any one of claims 1 to 12, characterized by , that the insulating body (140,240,260,340) has openings or recesses for filling with MgO powder or granules (150,250,350). [14] Heating cartridge (100, 200, 300) according to any one of the preceding claims, characterized by, that a press contact is made between the connecting wires for contacting the leads (133,134,233,234,333,334,338,339) of the temperature sensor (130,230,330,335) and the leads (133,134,233,234, 333,334,338,339) of the temperature sensor (130,230,330,335) and / or that a press contact is made between connecting wires for contacting the electrical heating element (121,221,321) and the electrical heating element (121,221,321).

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