EP2211588B1 - Contact element for the heating coil of a tubular heating element and manufacturing method of same - Google Patents

Abstract

The connecting element (32-1) has a protrusion (55-1) for holding and for electrical connection with a heating coil at a connection end (50-1). A fixing element (56-1) fixes the heating coil to and/or on the protrusion. The fixing element is formed such that the fixing element fixes a hook and/or a winding of the heating coil to and/or on the protrusion by plastic deformation, in a form-fit manner. The hook is located at a connecting end of the heating coil. The fixing element contacts the protrusion, in an electrically conductive manner. An independent claim is also included for a heating device.

Description

The present invention generally relates to the connection of an annealing or heating coil in a heating device. In particular, the invention relates to a novel connection element for connecting the heating coil to a connection assembly of a tubular heater without requiring a welding or soldering operation.

From the DE 1 156 906 A is a power connector for electric tubular heater is known in which one end of the heating wire in a bridging sleeve of easily bendable conductor material, preferably river iron, is inserted and that both parts are connected by crimping.

From the DE 18 41 985 U An arrangement for connecting a Heizwendelendes with a connection screw is known, wherein the screw has an axial bore and the Heizwendelende is inserted into this bore and pressed therein.

From the DE 103 51 811 A1 For example, a heating assembly for electrical resistance heating devices with at least one resistance heating wire is known, wherein the end of the resistance heating wire is crimped to a connection element and various spatial constellations between connection element and resistance heating wire are proposed.

From the DE 10 2006 005 322 A1 For example, a heating device is known in which the ends of the heating wire are connected, for example by a weld, to a respective connection module. Here is a connection wire of a thermal overload protection connected to the end of a connecting bolt by a crimping or notching process.

Also from the DE 100 62 539 A1 a connection assembly for an electric heater is known.

The EP 0 086 465 A1 shows a tubular heater with double connection, in which in a known manner embedded in insulating heating coil
attached to a connecting bolt by welding. In one embodiment, a connecting tube, which is pressed onto the welding point, is pushed over the cylindrical part of the firing pin and the welding point. In the connecting tube, a substantially cylindrical fuse is inserted, which is attached to a connecting piece of wire. The tubular heater thus has a double connection, wherein the protruding from the tubular heater end of the connecting pipe has a direct electrical connection to the heating coil, while the protruding end of the connecting wire allows an electrical connection to the heating coil via the fuse.

From the German patent application DE 10 2006 005 322 A1 is a generic heater known. Fig. 1 shows as essential components or assemblies of the known heating device: a jacket tube 10, in which a contacted via a connection assembly 30 heating coil 20 by means of an insulating material 40 with respect to the jacket tube is electrically insulated but thermally conductive. The connection module is connected at its one end via a connecting bolt 32 with the heating coil 20. These individual components or assemblies will be briefly explained below.

The heating coil 20, which is arranged in the interior of the jacket tube 10, is made of a wound to a helix in current flow heating electrical resistance material. At the two free connection ends 21, the heating coil 20 is connected to the respectively arranged there connection assembly 30 via the connecting bolt 32. In order to facilitate the attachment of the heating coil 20 on the connecting bolt 32, this has at its end facing the heating coil 20 a conical portion 32 a.

At the conical portion 32a of the connecting bolt 32, a circular cylindrical portion 32b of the connecting bolt 32 connects. The latter is connected to a likewise at least approximately coaxial with the central longitudinal line of the jacket tube 10 arranged thermal overload protection 34 in such a way that a connecting wire 34a of the thermal overload protection 34 is connected in a blind hole in the right frontal end of the connecting bolt 32 by a pinch 32c. At the conically shaped, right end 34b of the thermal overload protection 34, which otherwise has a substantially circular cylindrical cross-section, another connecting wire 34c of the thermal overload protection 34 in a blind hole in a left frontal end of a fitting 36 with the thermal overload protection 34 in turn by a pinch 36a connected. The connecting piece 36 is led out of the jacket tube 10 to the outside and serves to connect the known heating device with a (not shown) electrical energy source.

At the right front end 10a of the jacket tube 10 is a closure bead 38. The closure bead 38 is made of a thermally deformable plastic and has four fill slots 38a distributed in the circumferential direction of the lock bead 38 in a uniform pitch. These filling slots 38a extend axially along the sealing bead 38. Webs 38b are provided between the individual filling slots 38a, the outer diameter of which corresponds at least approximately to the inner diameter of the jacket tube 10. At their outwardly facing end 38a lugs 38c are provided on the webs, which close the filling slots 38a after filling the jacket tube 10 with an insulating compound 40 by a thermal deformation process. How out Fig. 1 it can be seen that the closure bead 38 projects beyond the right end face 10a of the jacket tube 10 and is fixed there by means of two notches in the jacket tube 10 to the connection piece 36.

The connecting bolt 32 is preferably made of a good electrical current conducting material to u. a. Avoid heating the connection module during current flow due to ohmic losses. Therefore, copper would be particularly suitable as a material for the terminal bolt 32. However, there is a problem that copper has poor heat resistance, i. H. is not "heat resistant", and therefore tends to flow in the intended use of the heater. For this reason, a purely frictional connection between the connecting bolt 32 and the heating coil 20 is not suitable to ensure a permanent mechanical, in particular electrically reliable connection.

Under a non-positive connection is understood here as one which results from the application of pressure that can be generated by a suitable bias, z. B. compressive forces or frictional forces, wherein the cohesion of the parts connected by means of the frictional connection parts is ensured solely by means of these forces. Typically, forces to be transmitted occur tangentially to the surfaces of the connection partners involved in a purely frictional connection.

Accordingly, in the known connection between the heating coil 20 and the connecting bolt 32, the tensile forces occurring can only be transmitted reliably by means of a frictional connection, as long as the set by means of biasing adhesive force between connecting bolt 32 and heating coil 20 greater than or equal to the tensile force occurring by the in the tubular heater is applied under tension clamped heating coil is. However, since the above-mentioned behavior of copper leads to a reduction in these operating forces during operation, there is the risk that the heating coil clamped in the tubular heating element between the connection assemblies will become unstable Detaching connecting bolt, the tubular heater thus fails and then must be replaced.

Therefore, in the known heating device, the connecting bolt is preferably made of brass or another heat-resistant material and the heating coil additionally fixed material fit on the connecting bolt.

In this case, a material-bonded connection between the heating coil and the connecting bolt can be produced by means of the spot weld or by brazing or high-temperature soldering. Such a compound can be separated only by destruction of the compound, but is complicated in terms of their production, especially time-consuming and above all requires an ongoing quality inspection in the manufacturing process to avoid rejects.

It is an object of the present invention to propose a new connection between the heating coil and the connection module, which has the necessary mechanical and electrical properties and manages without additional material connection measures.

The above object is achieved by a connecting element with the features of claim 1 and by a heating device with such a connecting element having the features of claim 9. In each of the subsequent subclaims are advantageous embodiments or developments of this.

A first aspect of the invention relates to a connecting element, in particular in a heating device, in particular for household appliances, for heating a fluid, for connecting a heating coil to a connection assembly of the heating device. The connecting element according to the invention essentially has the following features: At a first connection end, a holding element for electrically connecting to and holding, in particular a connecting end of the heating coil, at least one fixing element for, in particular positive, fixing the heating coil on or on the holding element. The at least one fixing element is designed so that it by means of plastic deformation or plastic deformation in the preparation of the connection with the connection end of the heating coil this form-fitting or on the holding element fix and at the same time can make a reliable electrical current conductive contact between these connection partners.

In preferred embodiments, the connector has a second terminal end for connection to a component of the terminal assembly. For this purpose, at least one clamping element may be provided at the second connection end, which is adapted in particular by plastic deformation to the shape of a component of the terminal assembly with bias, so that this second terminal end during assembly, in particular by mating, with the component of the terminal assembly non-positively and electrically conductive is connectable.

To exclude a release of this connection, notches and / or recesses may be provided in the clamping element, can engage in the corresponding projections or latching elements, which are provided on the component of the terminal assembly when connecting, so that in addition to the already mentioned non-positive in addition to a positive connection can be made.

For the sake of clarification, it should be noted that here by a positive connection is to be understood that the connection by an interlocking of the two connection partners, arises, wherein forces caused by operating load, substantially normal, d. H. perpendicular to the surfaces of the two connection partners can be transmitted. In such a mechanical connection, the connection partners can not solve without or with interrupted power transmission. Furthermore, due to the normal forces in the connection points, there are no shifting transverse forces.

In certain embodiments of the connecting element, a heat conducting means, in particular a Wärmeleitzunge or a Wärmeleitkonus additionally provided on the holding element. The heat conducting means is designed such that it protrudes substantially concentrically into a connected heating coil in the mounted state with a predetermined length in order to conduct heat from the heating coil to the connecting element and thus to the thermal overload protection which is preferably connected to the second connection end, in order to ensure a reliable especially to ensure fast response of the overload protection. In certain embodiments of the connecting element, this heat-conducting agent can also serve as a "threading aid" in the production of the connection to the heating coil. The second function "Fädelhilfe" facilitates the, in particular automated, production of the connection to the heating coil by the end of the heating coil is guided by the Fädelhilfe such that the heating coil, in particular, the connecting end of the heating coil occupies a predetermined position to the holding element, so as to arrive with the holding element in a predetermined engagement.

The holding element of the connecting element according to the invention has a substantially planar coil support region, in which or on which there is a projection. The cross-section of the projection lying substantially parallel to the coil support region has in special embodiments a shape which is adapted to the shape of the inner cross-section of the connection end of the heating coil or resembles this shape. Ie. the shape of the peripheral surface of the projection is based on the shape of the connection end of the heating coil.

The connecting end of the heating coil may in certain embodiments of the compound according to the invention have an embodiment of the following group: a hook, an eye, a cylindrical turn or a loop. In other words, the projection of the retaining element and the connecting end of the heating coil are adapted to each other so that between them as a connection partners a positive connection similar to the connection between a hook and an eye or a loop and a post can be made.

The projection on the helical contact area can be produced as a circumferential, raised edge in the helical contact area by reshaping, in particular as the edge of a pot by deep drawing or the like or alternatively as a tubular, in particular annular, edge at a through hole by punching and / or thorns or the like.

In a first embodiment of the connecting element according to the invention, the projection is formed by an edge which is deep-drawn on a substantially circular through-hole in the coil support region. In a second embodiment of the connecting element according to the invention, the projection is formed by a material piece, for example a bolt or a piece of wire, inserted at a substantially circular through-hole in the coil support region, in particular by riveting.

At this point it should be noted that in certain embodiments, the projection can be designed to press this also by plastic deformation or plastic deformation in the preparation of the connection with the connecting end of the heating coil this form of a rivet form fit to press or fix and thereby already can make a reliable electrical current conductive contact between the projection and Wendelauflagebereich and the connection end of the heating coil.

In the second embodiment of the connecting element, the helical contact area can be angled or bent substantially at right angles relative to the second connecting end, so that the projection essentially in the axial direction of the connecting element, in particular in the direction of the continuation of the axial center longitudinal line passing through the radial cross section of the clamping element, oriented from the second terminal end oriented.

For a radially concentric alignment of the component of the connection module and of the heating coil, an offset section can ideally be provided between the first and second connection ends of the connection element. The offset section is shaped such that a central longitudinal axis of a heating coil connected to the holding element and a central longitudinal axis of a component of the connection assembly connected to the clamping element at the second connection end are aligned with one another. In other words, the offset section is preferably shaped so that a central longitudinal line of a heating coil brought into engagement with the holding element essentially coincides with a virtual axis corresponding to the continuation of the axial center line passing through the cross section of the component contacted by the clamping element.

In order to prevent inadvertent deformation of the offset portion, in particular during assembly of the unit of heating coil and connection assemblies in a jacket tube, can be provided in the offset section, in particular by means of at least one notch generated material stiffening.

The at least one fixing element on the holding element is preferably configured in the form of at least one tab-like section, which adjoins the coil-supporting region. The at least one fixing element is further configured so that it can be deformed by plastic deformation so as to positively fix a connection end of the heating coil on or on the projection of the retaining element in a positively locking manner and at the same time conduct the electric current with it , d. H. in the best case without contact resistance, to contact.

With regard to the production of the connecting element, it should be noted that an output element for this purpose can be produced particularly advantageously from a sheet, particularly preferably from copper, by punching. D. h., An intermediate form of the connecting element is a semi-finished stamped from a sheet metal. In a first embodiment, the connecting element essentially consists of only a single piece of sheet metal, ie, can be produced in one piece; in the alternative second embodiment described above, the projection is added as an additional part as a further component for the connecting element.

The invention also relates to a heating device, in particular a tubular heater, with a jacket tube, at least one arranged inside the jacket tube heating coil of an electrical Widerstandsheizdraht, which is embedded in an electrically insulating, heat-conducting insulating in the jacket tube, at least one connection assembly inside the Jacket tube is arranged and a for connecting the heating coil with a located outside of the jacket tube electrical energy source out of the jacket tube outwardly connected terminal end, and preferably at least one arranged in the region of the opening of the jacket tube, preferably integral, holding device. Finally, the connection assembly is connected by means of a connecting element according to the invention with the heating coil.

The connection assemblies of the heater contain in preferred embodiments at least one, in particular thermal, overload protection, d. H. it is preferably an overtemperature fuse which responds when a predetermined temperature is reached. This predetermined temperature is, in particular, a critical temperature for the continued operation of the heating device, which indicates an abnormal operating state of the heating device.

The integral holding device according to the invention is designed such that it can at least partially positively receive the components of the connection assembly and ensure their exact arrangement within the jacket tube. In addition to an easier assembly of the unit of heating coil and connection assemblies in a jacket tube brings the inventive integral holding device with other advantages.

Due to the positive reception of the components of the connection module, the mechanical connections between the individual components of the connection module are relieved of tensile forces. Since the individual components of the terminal assembly, ie the connecting bolt, possibly the thermal overload protection and the inventive connecting element have different shapes, going through the at least partially positive reception or insertion of the components of the terminal assembly in the, preferably integral, holding device on the connecting element or on Connection bolt introduced forces on the holding device directly into the jacket tube initiated. Thus, the mechanical and electrical connections between the connecting element and the overload protection as well as between the overload protection device and the connecting bolt do not have to transfer forces, which considerably reduces the risk of failure of these connections.

Next can be adjusted on the material of the holding device and its shape, the thermal contact resistance between the overload protection in the terminal assembly and the jacket tube, whereby the response of the overload protection can be better adjusted. The addressed thermal contact resistance consists in this case of the ratio of material of the holding device to the insulating material, which are located between the jacket tube and overload protection together and is therefore easily determinable. In operation, the overload protection is essentially subjected to heat, which is passed from the heating coil via the connecting element to the overload protection. Therefore, copper as an excellent conductor of heat due to these considerations is particularly suitable as a material for the connecting element. Furthermore, the configuration of the second connection end of the connecting element according to the invention for the aspect of heat conduction and heat transfer in particular in relation to the known connection is of particular advantage.

For this purpose, the integral holding device has recesses, in particular in the area of the overload protection, so that the overload protection is at least partially surrounded by the insulating tube between the jacket tube such that a predetermined amount of heat per unit of time can be dissipated from the overload protection to the jacket tube via the insulating mass essentially corresponds to an amount of heat which is supplied in the proper operation of the heater via the second terminal end of the connecting element of the overload protection. Thus, the response of the overload protection can be set very accurately.

To fix the connection assemblies in the jacket tube, this can be notched in the region of the connection assembly, in particular in a region of the holding device in which the overload protection is not located, preferably in the region of the holding device in which the connection bolt runs, by a squeezing or pressing operation, d , H. be reduced selectively or along a line, the inner diameter of the jacket tube.

The connecting end of the heating coil has the form of a hook, an eye or a loop for connection to a connecting element according to the first embodiment, wherein the inner cross section of this shape substantially to the outer cross section corresponds to the projection on the holding element of the connecting element. In a specific embodiment, the terminal end of the heating coil, in particular by reshaping of the electrical coil heating wire forming the heating coil, is configured such that the hooked, looped or looped terminal end of the heating coil plane is substantially perpendicular to the cross section of a turn of the heating coil spanned level lies.

In contrast, the connection end of the heating coil for connection to a connecting element according to the second embodiment over the known in the Fig. 1 illustrated heating coil unchanged.

Since a heating device according to the invention can be produced without crystallization annealing, it is possible to use a siliconized insulating compound, in particular siliconized magnesium oxide, as the insulating compound. Since siliconized magnesium oxide is hydrophobic, a complex hermetic seal of the heater can be omitted. Of course, the insulating material may also be conventional magnesium oxide, wherein the heater is then sealed to the outside with, for example, a thermoplastic sealing bead, which closes off the jacket tube medium-tight.

In the heating device described above, during assembly of the heater, the entire preassembled unit consisting of the heating coil, which is connected at their respective ends in each case with a connection assembly, wherein a connection assembly again from the one hand by means of the connecting element according to the invention with the heating coil and on the other hand with the thermal overload fuse connected connection pin, the thermal overload protection itself and the holding device, in which the components of the terminal assembly are inserted form-fitting, are inserted before filling the insulating in the jacket tube.

In particular, by the configuration of the respective terminal assembly receiving integral holding device on its outer side with at least one over the entire axial length of the holding device extending filling slot, it is possible to fill the insulating material in this way over this at least one prefilled jacket tube. If the holding device has on its outer side a plurality of filling slots, preferably in the circumferential direction in a uniform pitch, the filling process can be carried out more quickly.

It is also possible, at a front end of the heater or the jacket tube, the holding device without Füllschlitze or additionally provide a so-called sealing bead, which has no Füllschlitz. Consequently, this jacket tube end is then sealed against leakage of the insulating material from the jacket tube during filling by the other jacket tube end. A holding device with at least one filling slot is then provided at the other front end of the casing tube.

After filling the insulating via the filling slots in the interior of the jacket tube, the at least one filling slot is closed. This can be done, for example, by providing at least one deformable closure nose on the holding device adjacent to a filling slot, on its side facing away from the casing tube interior. This deformable closure nose can be deformed after the filling process to close the filling slot medium-tight. This can be done, for example, that the at least one locking lug of the holding device consists of a thermally deformable plastic, so that this closing process can be carried out with a hot stamping tool. If the holding device has a plurality of filling slots, then such a closure nose is provided correspondingly for each of these filling slots.

An alternative to closing the filling slot or slots on the holding device is that of the holding device in the direction of the outside of the jacket tube, d. H. in the direction of the jacket tube opening a sealing bead connects, which closes the jacket tube medium-tight. As a further alternative, the at least one filling slot on the holding device can also be achieved by injecting a sealing means such as a synthetic resin or a plastic.

As already mentioned, in the heating device according to the invention already a jacket tube can be used, which has the desired final diameter, which can be used for corresponding flange assemblies and the like. To compress the insulating the jacket tube is subjected only in sections or over the entire axial length of a pressing operation to achieve the required compression of the insulating material. This pressing process can be carried out simultaneously with a forming of the jacket tube or thereafter. Advantageously, it is no longer necessary to reduce the jacket tube in its Dürchmesser by rolling, whereby the subsequent recrystallization annealing is eliminated.

By eliminating the need to make a Rekristallisationsglühen, just gives the opportunity to use instead of the insulating compound previously used, namely magnesium oxide, a siliconized magnesium oxide and for the integral holding device, a thermally deformable plastic. Also, a seal or sealing of the tubular heater z. B. by thermoset (synthetic resin) omitted.

In this context, it should be noted that it is of course fundamentally further possible to use a conventional insulating compound such as magnesium oxide as an insulating material and finally sealing the heating device externally with a thermoelastic sealing bead or sealing bead which hermetically seals the jacket tube, in any case in a medium-tight or fluid-tight manner or to be sealed. In this case, the heater may be additionally sealed to the outside with a covering resin.

Fig. 1

eine perspektivische Teilschnittansicht einer bekannten Heizvorrichtung;

Fig. 2a

eine perspektivische Ansicht eines Verbindungselements gemäß einem ersten Ausführungsbeispiel der Erfindung;

Fig. 2b

eine perspektivische Ansicht eines Verbindungselements der Fig. 2a mit angefügter Heizwendel vor deren mechanischen Verbindung;

Fig. 2c

eine perspektivische Ansicht eines Verbindungselement der Fig. 2a mit angefügter Heizwendel nach deren mechanischen Verbindung;

Fig. 2d

eine perspektivische Ansicht eines Abschnitts einer erfindungsgemäßen Heizvorrichtung, insbesondere ein Ende eines Mantelrohres mit einer integ- rierten Anschlussbaugruppe und einem Verbindungselement gemäß Fig. 2a mit angefügter Heizwendel nach deren mechanischen Verbindung;

Fig. 3a

eine perspektivische Ansicht eines Verbindungselements gemäß einem zweiten Ausführungsbeispiel der Erfindung;

Fig. 3b

eine perspektivische Ansicht eines Verbindungselements der Fig. 3a mit angefügter Heizwendel vor deren mechanischen Verbindung;

Fig. 3c

eine perspektivische Ansicht eines Verbindungselement der Fig. 3a mit angefügter Heizwendel nach deren mechanischen Verbindung;

Fig. 4

eine perspektivische Ansicht auf einer integralen Halteeinrichtung für eine Anschlussbaugruppe einer Heizvorrichtung der Erfindung.

Further advantageous embodiments and an embodiment of the heating device according to the invention are explained below in conjunction with the drawing figures. The terms "left", "right", "top" and "bottom" used in the description of the embodiment refer to the drawing figures in alignment with normal readable reference numerals and figure names. Here is:

Fig. 1

a partial perspective sectional view of a known heating device;

Fig. 2a

a perspective view of a connecting element according to a first embodiment of the invention;

Fig. 2b

a perspective view of a connecting element of Fig. 2a with added heating coil before their mechanical connection;

Fig. 2c

a perspective view of a connecting element of Fig. 2a with added heating coil according to their mechanical connection;

Fig. 2d

a perspective view of a portion of a heating device according to the invention, in particular an end of a jacket tube with an integrated connection assembly and a connecting element according to Fig. 2a with added heating coil according to their mechanical connection;

Fig. 3a

a perspective view of a connecting element according to a second embodiment of the invention;

Fig. 3b

a perspective view of a connecting element of Fig. 3a with added heating coil before their mechanical connection;

Fig. 3c

a perspective view of a connecting element of Fig. 3a with added heating coil according to their mechanical connection;

Fig. 4

a perspective view of an integral holding device for a connection assembly of a heating device of the invention.

Well with respect to the Fig. 2a . 2 B , and 2c , in which a first embodiment of a connecting element according to the invention 32-1 is shown in a perspective view, in addition to the connecting element itself, the preparation of the inventive connection between a heating coil and this connecting element is explained.

With regard to the second embodiment of a connecting element 32-2 according to the invention, which in the Fig. 3a . 3b and 3c is shown in a perspective view, it should be noted that this is described in each case with emphasis on the possibly differences together with the first embodiment. As a result, unnecessary repetitions are avoided, but also correlations to understand the general connection principle according to the invention better understood. It goes without saying that, in addition to the exemplary embodiments described here, alternative embodiments can be recognized by the person skilled in the art, who make use of the principle of the invention explained in this description with due appreciation.

Fig. 2a shows the first embodiment of a connecting element 32-1 according to the invention that can be made substantially in one piece from a sheet by punching and subsequent forming, such as cold forging. The connecting element 32-1 has two connection ends, namely a first connection end 50-1 for connection to a heating coil (20, cf. Fig. 2b . 2c and 2d ) and a second connection end 60 for connection to a connection module, in particular for connection to a thermal overload protection (34, cf. Fig. 2b . 2c and 2d ) or overtemperature protection. This second connection end 60 will be described in more detail below for both exemplary embodiments of the connection element 32-1 and 32-2 according to the invention explained here.

The first terminal end 50-1 of the connector 32-1 according to the first embodiment has a substantially planar coil support portion 54-1. In or on this coil support region 54-1 there is a projection 55-1, which is produced, for example, as a rim on a hole 53-1 by means of spikes during the forming of a stamped outlet piece of sheet metal. The projection 55-1 here has the shape of a tubular rim, which adjoins the hole 53-1 in the coil support region 54-1. Of course, the projection 55-1 also by deep drawing in the planar helical contact area have been pressed, the helical contact area then would have no through hole.

Between the first connection end 50-1 and the second connection end 60 there is a material section which is designed as an offset region 58-1 and connects the two connection ends 50-1 and 60 to one another. The alignment function of the offset portion 58-1 for aligning the two terminal ends will be explained in more detail below.

On one side of the coil support region 54-1, opposite the side to which the offset region 58-1 adjoins, there is a tapered heat conducting tongue as heat conducting means for the thermal coupling of the connecting element to the heating coil. This Wärmeleitzunge extends or projects in the assembled state (see. Fig. 2b . 2c . 2d ) with a predetermined length substantially concentrically into the connected heating coil 20 and acts as a heat conducting means to conduct heat generated by the heating coil to the connecting element 32-1 and thus also to the second connection end 60 Favor connected thermal overload protection 34 or to transfer. This ensures a reliable, in particular fast response of the overload protection 34.

At one of the remaining side edges of the coil support portion 54-1 is followed by a tab-shaped fixing element 56-1, which in the illustration of Fig. 2a already bent by the subsequent punching from a sheet metal forming process substantially to the coil support region vertically upward, ie directed away from the coil support region 54-1. The fixing element 56-1 designed as a fixing strap can, as described below Fig. 2c is deformed by bending the fixing tab in the direction of the projection 55-1 to a laid around the projection 55-1 connecting end of the heating coil (21-1, Fig. 2b ) and to secure against detachment.

Fig. 3a shows a second embodiment of a connecting element according to the invention 32-2, which is essentially made of two parts, namely a made of a metal sheet by punching and subsequent cold forming main body and a heat conducting in the form of a Wärmeeitkonus 51-2 and the projection 54-2 forming piece of material.

The second embodiment of the connecting element 32-2 according to the invention, like the first exemplary embodiment, has two connection ends, namely a first one Connecting end 50-2 for connecting to the heating coil (20, see. Fig. 3b and 3c ) and the second terminal end 60 for connection to a terminal assembly which is identical to the first embodiment. Therefore, only the first terminal end 50-2 differently shaped for the first embodiment will be explained below. As noted above, the identical second terminal end 60 for both embodiments will be described in more detail below.

The first connection end 50-2 of the connection element 32-2 according to the second embodiment also has a substantially planar coil support region 54-2 which, however, is folded at right angles compared to the first embodiment, so that the planar coil support region is arranged parallel to the radial cross section of the second connection region , Compared to the first embodiment, the coil support portion 54-2 of the second embodiment is rotated by 90 °.

In or on the coil support region 54-2 is a projection 55-2, which is now attached by means of an attached piece of material, here in the form of a cylindrical piece, to the coil support portion 54-2. At the cylindrical, the protrusion forming piece of material is followed by a, in particular frusto-conical, ie tapered, material portion, in the form of a Wärmeleitkonus 51-2 as a heat conduction with the in connection with the Fig. 2a function already described functions.

The piece of material forming the projection and the material portion forming the heat-conducting means are preferably produced in one piece and, for example, in the form of a rivet, ie in a form-fitting manner, in a hole (in FIG Fig. 3a not shown) in the coil support area 54-2 attached. Alternatively, the attachment can also be made material fit by welding or hard or high temperature soldering.

At two, opposite side edges 54-2a and 54-2b of the coil support portion 54-2 each includes a tab-shaped fixing element 56-2a and 562b, d. h, a total of two, which in the presentation of the Fig. 3a already by the subsequent stamping from a sheet metal forming process substantially to the coil support portion 54-2 vertically upwards, ie the coil support portion 54-2 away, ie directed in the direction of Wärmeeitkonus 51-2, are bent. These fixing elements 56-2a and 56-2b, which are designed as fixing straps, can, as described below Fig. 3c is shown, so-deformed by so-called crimping or a squeezing operation of the fixing tabs in the direction of the protrusion 55-2, about a connecting end of the heating coil (21-2) pushed onto the protrusion 55-2, Fig. 3b ) to fix positively and secure against detachment. Of course, could at the remaining free edge of the coil support portion 54-2 still another, ie third, fixing tabs are provided.

Now, referring to the Fig. 2a and 3a the second terminal end 60, which is the same for both embodiments of the connecting element according to the invention 32-1 and 32-2 described. The second connection end 60 has two clamping elements 61a and 61b, which together form a clamping means for connection to a component (34, FIG. Fig. 2b . 2c . 2d . 3b . 3c ) of a terminal assembly (30, Fig. 2d ) form.

The component to be contacted of the terminal assembly is preferably a thermal overload fuse 34 or overtemperature fuse, which may be, for example, a fuse that interrupts the electrical connection between the heating coil 20 and a (not shown) power source when a predetermined temperature is exceeded.

The two clamping elements 61a and 61b are, in particular by plastic deformation, to the shape of this component to be contacted, d. H. the overload protection, the terminal assembly adapted with a bias that the second terminal end 60 by joining, especially mating, with this component non-positively and electrically conductive to the terminal assembly is connectable.

In the embodiments shown in the figures, the second terminal end 60 is provided for connection to a substantially cylindrical portion of the overload protection. Therefore, the two clamping elements 61a and 61b are adapted by plastic deformation, to exactly this cylindrical shape. The abovementioned prestressing is thus produced in that a slotted cylinder jacket clamped by the two clamping elements 61a and 61b has an inner diameter which is slightly smaller than the outer diameter of the overload safety device (34, FIG. Fig. 2b, 3b ).

The tubular end face 60a of the second terminal end 60, which is formed substantially by edges of the clamping elements 61a and 61b, is away from the connecting element 32-1 or 32-2 via a section 60b like a funnel, i. H. funnel-shaped, widened, so that the component to be contacted to the terminal assembly can be easily connected by means of nesting.

The following is the preparation of a in the Fig. 2c and 3c illustrated inventive connection between a heating coil and a connecting element 32-1 and 32-2 of the invention with reference to a in the Fig. 2b and 3b illustrated intermediate step explained.

The Fig. 2b and 3b each show a connection end 21-1 and 21-2 of the heating coil 20, which by means of the secondary function "Fädelhilfe" of the heat conduction (in the Fig. 2b and 3b each covered by the heating coil 20) has been brought to the first terminal end 50-1 and 50-2 in a certain position to each other.

In Fig. 2b is the connection end 21-1 of the heating coil 20 in the form of a loop. The plane spanned by this loop is due to a corresponding deformation of the heating coil 20 forming resistance heating substantially perpendicular to the spanned by the turns of the heating coil radial cross-sectional areas and thus parallel to the coil support surface 54-1 of the connecting element 32-1. Good is in Fig. 2b to recognize that the connecting end 21-1 of the heating coil 20 is already positively connected to the holding element 52-1 of the connecting element 32-1 by the connecting end 21-1 of the heating coil 20 in the form of a loop around the projection 55-1 at the coil support region 54th -1 is placed.

The projection 55-1, which is here formed and serves as a cylindrical hanger, is deformed in preferred embodiments in the form or type of riveting and so formed or pressed over the loop or loop of the connecting end 21-1 of the heating coil 20 to the connecting end Pre-fix 21-1. The actual fixing element 56-1 is in the Fig. 2b still unchanged, ie, the connection end 21-1 of the heating coil is not yet finally determined and thus the electrical contact, in particular its contact resistance is not optimal.

In the Fig. 3b The connecting end 21-2 of the heating coil 20 consists essentially of the end of the heating coil 20 itself. This connecting end 21-2 of the heating coil 20 is connected to the holding element 52-2 of the connecting element 32-1 by pushing or attaching the connecting end 21-2 the (in the Fig. 3b covered by the heating coil) Wärmeeitkonus (51-2, Fig. 3a ), wherein the last turn of the heating coil 20 is applied to the coil support region 54-2. The two fixing elements 56-2a and 56-2b are in Fig. 3b still unchanged, ie, the connection end 21-2 of the heating coil 20 is not yet fixed to the connecting element and also the electrical contact, in particular its contact resistance is still not optimal.

The Fig. 2c and 3c show against the Fig. 2b and 3b each of the connecting end 21-1 and 21-2 of the heating coil 20, which by means of the respective fixing elements 52-1 and 52-2a and 52-2b is secured to the respective projections 55-1 and 55-2 both positive and non-positive.

In the Fig. 2c the loop-shaped connection end 21-1 of the heating coil 20 is fixed by bending over or folding over the fixing element 56-1 designed as a fixing tab on the coil support surface 54-1 of the connection element 32-1. The bent fixing element 56-1 secures the connecting end 21-1 of the heating coil 20 and also ensures excellent electrical contact, in particular a low contact resistance.

In the Fig. 3c the connection end 21-2 of the heating coil 20 is fixed by so-called crimping or crimping of the fixing elements 56-2a and 56-2b designed as fixing lugs on the projection 55-2 attached to the coil support surface 54-2 of the connection element 32-2. The crimped fixing elements 56-2a and 56-2b secure the connecting end 21-1 of the heating coil and ensure excellent electrical contact, in particular, low contact resistance.

To the in the Fig. 2a 3a or 3a, it should be noted that between the first terminal end 50-1 and 50-2 and the second terminal end 60 is an offset range 58-1 or 58-2, the essentially serves to align the two connection ends 50-1 or 50-2 and 60 to one another in such a way that a virtual central longitudinal axis of a heating coil 20 connected to the first connection end 50-1 or 50-2 essentially has a virtual central longitudinal axis of second terminal end 60, in particular the adjoining thereon overload protection 34, is aligned, that is substantially rectified or runs with the smallest possible distance to this parallel. In order to stiffen the offset area 58-1 or 58-2 against unintentional bending, a notch 58a for stiffening is provided in the offset area.

Now, reference is made Fig. 2d taken a perspective view of a portion of a heating device according to the invention, in particular an end of a jacket tube 10 with an integrated terminal assembly 30 and a connecting element according to that in connection with the Fig. 2a to 2c illustrated embodiment with added heating coil 20 after the mechanical connection shows. With regard to the details of the connecting element is on the Fig. 2a to 2c directed.

The jacket tube 10 of the heater consists of a sufficient or good heat-conducting material, such as stainless steel or aluminum, and has at least one approximately circular cross-section, but depending on the application, other cross-sections are possible. The two front ends 10 a of the jacket tube 10 are open to the outside, wherein in the Fig. 2d only one of the two front ends 10a is shown.

Although not shown, it should be noted that the jacket tube 10 can be brought into any external shape. Depending on the application, the jacket tube z. B. be designed as a straight tube or be bent in the shape of the letter "U" or "W". Of course, other forms than those mentioned are possible.

In contrast to casing pipes known heating devices, the jacket tube 10 from the beginning, ie already at the beginning of mounting the arranged in the casing 10 components or assemblies on the outer diameter D _a , it in the installed state, for example in a fluid container in a dishwasher or owns a laundry washing machine.

In Fig. 4 For clarity, an integral holding device 38 * of the invention is optional. The holding device 38 * is made of a thermally deformable plastic. As well as from the Fig. 2b . 2c and 2d , there with 38-1 denoted, as well as from the Fig. 3b . 3c and 3d, there denoted by 38-2, can be seen, the holding device 38 * distributed over its circumference filling slots 38a * on. These filling slots 38a * extend over the entire axial length of the holding device 38 *. Webs 38b * are provided between the individual filling slots 38a * which essentially determine the outer diameter D _a * of the holding device 38 *, which at least approximately corresponds to the inner diameter D _{i of} the jacket tube 10.

As already explained, the holding device 38 * is designed to receive the components of the connection assembly in a form-fitting manner, in order to relieve the mechanical connections between the individual components (connecting element, overload protection and connection pin) of the connection assembly of tensile forces. Since the individual components of the connection assembly, ie the connecting bolt, possibly the overload protection as well as the connecting element according to the invention have different forms, are by the positive reception or insertion of the components of the terminal assembly in the, preferably integral, holding device 38 * on the connecting element 32-1 and 32-2 or introduced at the connecting bolt 36 forces via the holding device 38 * directly into the jacket tube 10 introduced. Thus, the mechanical and electrical connections between connecting element and overload protection as well as between overload protection transmitted and connecting bolts substantially no forces, which significantly reduces the risk of failure of these compounds.

As also already mentioned, in the integral holding device 38 * in the region 34a, which is to receive the overload protection 34, recesses 34b, so that the overload protection is later surrounded by the insulating tube 40 at least partially between the jacket tube 10 after installation in the jacket tube 10 can be removed from the overload protection 34 to the casing 10 via the insulating material 40, a predetermined amount of heat per unit time. This amount of heat preferably corresponds to that amount of heat that is supplied to the overload protection 34 via the second connection end 60 of the connecting element 32-1 or 32-2 in the proper operation of the heating device. Thus, the response of the overload protection 34 can be set very accurately.

In this context, in addition to the material of the holding device 38 * and its shape, the thermal contact resistance between the overload protection 34 in the terminal assembly 30 and the jacket tube 10 can be adjusted, whereby the response of the overload protection can be set more accurately.

The above-mentioned thermal contact resistance is made up of the ratio of material of the holding device 38 * to insulation material 40, which are located between jacket tube 10 and overload protection 34 or overtemperature protection together and is therefore easily determinable.

During operation, the excess temperature fuse is essentially subjected to heat, which is conducted by the heating coil 20 via the connecting element 32-1 or 32-2 to the overload protection. In particular, the configuration of the second connection end 60 of the connecting element according to the invention is here opposite to the connection in the heating device in Fig. 1 Of particular advantage, since 60 via the clamping means of the second connection end heat is particularly well supplied over the entire cylindrical circumference of the overload protection 34 and not only on the thermal constriction 34 a as in in Fig. 1 illustrated heater.

Finally, it should be noted that on the holding device 38 * at its at the casing tube end 10 a outwardly facing end of the webs 38 b * lugs (in Fig. 2d not shown) can be provided, which after a filling operation of the heater with an insulating material 40, as will be explained in more detail below, closing the filling slots 38a * by means of a thermal deformation process.

How out Fig. 2d it can be seen, the holding device 38 * over the right front end 10a of the jacket tube 10 something over. The holding device can be fixed in its axial position by means of notches in the jacket tube, for example in the region of the jacket tube 10, in which runs in the interior of the connecting bolt 36.

It should also be noted that the region of the second connection end 60 of the heating device according to the invention on the side not shown can be constructed as well, as explained above. Alternatively, there is the possibility that, instead of the above-described holding device 38 *, another holding device is used, for example one which has no filling slots and whose outer diameter substantially corresponds to the inner diameter of the jacket tube 10. This holding device can then be fixed, for example, by an adhesive process in the local end of the jacket tube 10. Alternatively, in the region of the connection assembly, in particular in a region of the holding device in which the overload protection is not located, preferably in the region of the holding device in which the connection bolt extends, the inner diameter of the jacket tube 10 is notched by a crimping or pressing operation, d. H. be reduced selectively or along a line so as to fix the holding device in the jacket tube.

In the following, the production of a heating device according to the invention will be briefly explained. After the heating coil 20 has been inserted with the attached at its two ends terminal assemblies 30 in the interior of the jacket tube 10 and fixed in position with respect to the axial arrangement by means of the holding device 38 *, via the filling slots 38a * at the at least one holding device 38 * a, in particular made of siliconized magnesium oxide, insulating 40 are filled. The insulating compound 40 is used for electrical insulation of the heating coil 20 of electrical resistance heating wire and the electrical current-carrying components of the terminal assembly 30, d. H. Moreover, the insulating material conducts the heat generated by the heating coil 20 to the jacket tube 10.

After the insulating compound 40 has been completely filled by the pointing to the inside of the jacket tube 10 end face of a holding device 38 to the also facing the inside end face of the other holding device 38, the filling slots 38a can be closed medium-tight, z. B. by a thermal Deformation process of closure lugs or by closing by means of a suitable sealant such as a thermosetting plastic. In this context, it should be noted that when using a siliconized insulating such. As siliconized magnesium oxide, the sealing of the front ends of the jacket tube no longer require a special seal, since siliconized magnesium oxide is water-repellent or hydrophobic. Ie. the front ends of the jacket tube need only be closed in order to prevent the insulating material from falling out of the interior of the heating device, for example during vibrations caused by a spinning process in a laundry washing machine, or being shaken out.

Claims (15)

1. Connection element (32-1; 32-2) for connecting a heating coil (20) to a terminal assembly (30) in a tubular heating element, wherein the connection element comprises:

   at a first terminal end (50-1; 50-2) a holding element (55-1; 55-2) for electrically connecting to and holding of the heating coil (20),

   at least one fixing element (56-1; 56-2a, 56-2b) for fixing the heating coil to or on, respectively, the holding element (55-1; 55-2),

   wherein the at least on fixing element is designed in such a manner that it can fix, by means of plastic deformation, at least one hook arranged at a connection end (21-1; 21-2) of the heating coil or at least one turn of the heating coil, respectively, at or on, respectively, the holding element and electroconductively contact with the same, in a form-locking manner without any additional material-locking connection measures.
2. Connection element according to claim 1, further comprising at least one clamping element (61a: 61b) at a second terminal end (60) for connection to a component (34) of the terminal assembly (30),
   wherein the at least one clamping element is adapted, in particular by means of plastic deformation, with pretension to the shape of the component of the terminal assembly in such a manner that the second terminal end is frictionally and electroconductively connectable to the terminal assembly by joining or sticking together with this component.
3. Connection element according to one of the preceding claims, further comprising a heat conducting means, in particular a heat conducting tongue (51-1) or a heat conducting cone (51-2),
   wherein the heat conducting means is designed so as to extend substantially concentrically with a predetermined length into a connected heating coil (20) in a mounted condition in order to conduct heat from the heating coil to the connection element.
4. Connection element according to one of the preceding claims,
   wherein the holding element (55-1; 55-2) has a substantially planar coil support region (54-1; 54-2),
   wherein the coil support region has a protrusion (55-1; 55-2), and
   wherein a cross section of the protrusion in a direction substantially parallel to the coil support region has a shape substantially adapted to the shape of an inner cross section of the connection end (21-1; 21-2) of the heating coil (20).
5. Connection element according to claim 4,
   wherein the protrusion consists of edges in the coil support region which are drawn upward by reshaping, or
   wherein the protrusion (55-1) consists of an edge deep-drawn at a substantially circular through hole (53-1) in the coil support region (54-1), or
   wherein the protrusion (55-2) consists of a material piece, in particular a bolt, inserted in a form-locking or material-locking manner at a substantially circular through hole in the coil support region (54-2).
6. Connection element according to one of the claims 4 or 5,
   wherein the coil support region (54-2) is substantially orthogonally folded with respect to the second terminal end (60) in such a manner that the protrusion (55-2) is directed away from the second terminal end in an axial direction of the connection elements (32-2), wherein the longitudinal center lines of the connection elements and the protrusion are aligned.
7. Connection element according to one of the preceding claims,
   wherein an offset portion (58-1; 58-2) is provided between the first (50-1; 50-2) and the second (60) terminal end,
   wherein the offset portion (58-1; 58-2) is shaped in such a manner that a longitudinal center line of a heating coil connected to the holding element (52-1; 52-2) and a longitudinal center line of a component of the terminal assembly connected to the clamping element (61a; 61 b) at the second terminal end are aligned,
   wherein in the offset portion (58-1: 58-2) optionally a reinforcement (58a) is provided which in particular consists of a notch.
8. Connection element according to one of the preceding claims 5 to 7,
   wherein the at least one fixing element (56-1; 56-2a, 56-2b) is designed in the form of at least one lug-like portion at the coil support region (54-1; 54-2), and
   wherein the at least one fixing element is reshapeable by plastic deformation in such a manner that a connecting end (21-1; 21-2) of the heating coil (20) which is arranged around the protrusion can be fixed in a form-locking manner at or on, respectively; the protrusion (55-1; 55-2) and electroconductively connected to the same.
9. Tubular heating comprising
   a casing tube (10),
   at least one heating coil (20) arranged inside the casing tube (10) and made of an electric resistance heating wire embedded in an electrical isolating and heat conducting isolating compound (40) within the casing tube (10),
   at least one terminal assembly (30) arranged inside an end region of the casing tube (10) having a connecting end led out of the casing tube (10) for connecting a connecting end of the heating coil (20) with an electric power source arranged outside of the casing tube (10),
   characterized in that
   a connection is provided between a connecting end (21-1; 21-2) of the heating coil (20) and the terminal assembly (30) by means of a connection element (32-1; 32-2) according to one of the claims 1 to 8 without additional material-locking connecting measures.
10. Heating device according to claim 9,
    wherein the connecting end (21-1) of the heating coil (20) is designed in the form of a hook, an eye or a loop, and wherein an inner cross section of the connecting end substantially corresponds to a outer cross section of the protrusion (55-1; 55-2) at the holding element (52-1; 52-2),
    wherein preferably a plane spanned by the hook-like, eye-like or loop-like designed connecting end (21-1) of the heating coil (20) is arranged substantially perpendicular to a plane spanned by the cross section of a turn of the heating coil, by means of reshaping the electric resistance heating wire providing the heating coil.
11. Heating device according to one of the claims 9 to 10, wherein the heating device further comprises
    at least on integral holding device (38*) arranged in the region of the orifice of the casing tube (10),
    wherein the integral holding device is adapted to receive components of the terminal assembly, and
    wherein the terminal assembly is arranged at least partially in a form-locking manner in correspondingly shaped recesses in the integral holding device (38*).
12. Heating device according to one of the claims 9 to 11,
    wherein the terminal assembly (30) comprises at least one overload protection (34), in particular a thermal overload protection.
13. Heating device according to one of the claims 11 or 12,
    wherein the integral holding device (38*) comprises recesses, in particular in the region of the overload protection (34), in such a manner that the overload protection (34) is at least partially surrounded by the isolating compound (40) arranged between the overload protection and the casing tube (10), so that a predetermined heat quantity per time unit can be dissipated from the overload protection (34) via the isolating compound (40) to the casing tube (10), substantially corresponding to a heat quantity which is applied to the overload protection (34) via the second terminal end of the connection element during normal operation of the heating device.
14. Heating device according to one of the claims 11 to 13,
    wherein at the outside of the integral holding device (38*) at least one filling slot (38a) extending over the whole axial length of the holding device is provided for filling the isolating compound (40) into the heating device during production of the same, and
    wherein the isolating compound (40) is a hydrophobic, in particular siliconized compound, preferably a siliconized magnesium oxide.
15. Heating device according to one of the claims 11 to 14,
    wherein the casing tube (10) is crimped or notched in the region of the terminal assembly, in particular in the region of the holding device (38*) in which the terminal bolt is arranged, for fixing the holding device (38*) in the casing tube (10).

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