Patent Grant
10219322
This application claims the benefit of priority under 35 U.S.C. ยง 119 of German Patent Application DE 10 2014 109 720.3 filed Jul. 10, 2014, the entire contents of which are incorporated herein by reference.
The present invention pertains to an electric heater having a metal sheath defining an interior space, at least one electric heating element, arranged in the interior space and electrically insulated by an insulating material filling and electric terminals for the at least one electric heating element and pertains to a process for manufacturing such a heater. Such electric heaters include, for example, heating cartridges, which are used, among other things, to heat many different components in the automobile industry, for example, for heating map-controlled thermostats.
Prior-art heating cartridges have an often tubular metal sheath, which defines a tubular interior space. An electric heating element, which is usually designed as a heating wire winding on a coil support and is advantageously insulated electrically against the metal sheath by an insulating material filling, is arranged in this tubular interior space. To ensure the power supply for the electric heating element, connection wires, which are in electric contact with the heating wire winding, are led out of the metal sheath. A plug contact, e.g., a connection pin, a connection tongue or a connection jack are crimped or welded to these sections of the connection wires, which are led out of the metal sheath, such that there is a continuous electric contact between the plug contact and the electric heating element.
However, it is problematic in these electric heaters known from the state of the art that the contact points thus formed between the connection wire and the plug contact have proved to be prone to failure, especially in environments in which vibrations may occur, which happens in nearly all applications in connection with motor vehicles. Moreover, an additional manufacturing step, which is also prone to failure, namely, the crimping or welding of the connection wire and the plug contact, is associated with them.
Thus, an object is to provide a reliable electric heater with plug-in connector, which can be manufactured in a simple manner. This object is accomplished by an electric heater having the features according to the invention and by a process for manufacturing an electric heater having the features according to the invention.
The electric heater according to the present invention has a metal sheath defining an interior space, with at least one electric heating element, which is arranged in the interior space of the metal sheath and is electrically insulated against the metal sheath by an insulating material filling, and with electric terminals for the at least one electric heating element. For example, tubular metal sheaths define an interior space.
It is essential for the present invention that at least one electric terminal is a plug contact of a one-piece design, which has a section arranged in the interior space of the metal sheath with a contact point arranged in the interior space of the metal sheath, at which the plug contact is conductively connected to the electric heating element. The conductive connection may take place directly to the electric heating element or indirectly with the use of an auxiliary wire arranged between the heating element and the plug contact.
The present invention is based on the finding that by shifting the contact points into the interior space of the metal sheath, these critical points can be effectively protected from vibrations and other disturbing effects and that such a shift is made possible by the use of one-piece plug contacts, which have, on the one hand, a section that can be moved into the interior space of the metal sheath and, on the other hand, an integrally molded connection pin, an integrally molded connection tongue or an integrally molded connection jack. In particular, such plug contacts may be embodied as stamped contacts.
Even though each electric terminal designed in this manner reduces the risk of failure of the electric heater, all electric terminals are plug contacts made in one piece in an especially advantageous embodiment, which have each a section arranged in the interior space of the metal sheath with a contact point, which is arranged in the interior space of the metal sheath and at which the plug contact is connected conductively to the electric heating element.
Especially good protection is achieved against vibrations and other disturbing environmental effects if the contact point is embedded in the insulating material filling. Even better protective effect is obtained if the insulating material filling is compacted at least at the site at which the contact point is embedded in it.
In a preferred embodiment of the present invention, the electric heating element is a heating wire coil, which is wound on a coil body and whose ends are inserted into holes of the coil support. Further, one section each of the plug contact is likewise inserted into the hole of the coil body, and the conductive connection between the plug contact and the electric heating element at the contact point is established by pressing this section of the plug contact with the end of the heating wire coil, which end is inserted there. This embodiment make especially efficient production possible, because the coil-covered coil body can be used as a prefabricated assembly unit in it and the contact point can be produced simultaneously with the compaction of the insulating material filling and it does not require any additional working step.
However, the conductive connection between the plug contact and the electric heating element at the contact point may also be established, as an alternative, by welding or by crimping. The contact point may now be located directly in the area of the coil body, but sections of the coil body may also extend, starting from the coil body, in the direction of the terminals, which can then be welded or crimped at any desired point in the interior space of the metal sheath.
An advantageous variant of these variants provides for the conductive connection between the plug contact and the electric heating element to be established via an auxiliary wire, which is in electric contact with the plug contact at the contact point, by the electric heating element being a heating wire coil wound on a coil body, whose ends are inserted into holes of the coil body, by one section each of the auxiliary wire being likewise inserted into the hole of the coil body, and by the conductive connection between the auxiliary wire and the electric heating element being established by pressing this section of the auxiliary wire with the end of the heating wire coil, which end is inserted there. This has the advantage that crimping or welding, which takes place here between the plug contact and the auxiliary wire, can still be performed outside the metal sheath, which considerably simplifies this working step.
As an alternative, pressing of these two conductors may also be performed at this point instead of crimping or welding the plug contact and the auxiliary wire. This may be achieved especially with the use of small ceramic tubes with corresponding holes in them. A section each of the plug contact and auxiliary wire is inserted for this into a hole of the small ceramic tube, and the small ceramic tube is subsequently pressed. This preferably happens, when the small ceramic tube with the inserted sections of the plug contact and auxiliary wire is received in the interior space of the metal sheath, together with the compaction of the insulating material filling.
In particular, it can be made possible, when using this alternative, to carry out the filling of the interior space of the metal sheath with insulating material before the insertion of the plug contacts, without this leading to the need to push plug contacts through the insulating material filling when the small ceramic tube is arranged such that its terminal-side end face presets the maximum filling height of the insulating material filling, i.e., when this surface is at the same level as the surface of the insulating material after filling or protrudes over this surface.
To bring about the plug-type connection proper, it proved to be advantageous if at least one section of the plug contact, which is arranged outside the metal sheath, is provided with a plug housing extrusion-coated around this section. In particular, such a plug housing may also be arranged such that it is received directly at the terminal-side end of the metal sheath or is even received partially in the terminal-side end of the metal sheath, which can contribute to a further minimization of the effect of vibrations on the plug-type connection. If the plug housing is also extrusion-coated around a section of the metal sheath or if the plug housing has a section that is received in the interior of the metal sheath and is pressed there, increased tensile strength of the overall arrangement can be achieved at the same time.
A process according to the present invention for manufacturing such electric heaters comprises the steps of providing a metal sheath defining an interior space, an electric heating element and at least one plug contact made in one piece, which has a section, which can be arranged in the interior space of the metal sheath; of arranging the electric heating element in the interior space of the metal sheath; of establishing an electric contact at contact points between the plug contact and the electric heating element; of inserting the section of the plug contact into the interior space of the metal sheath; of filling the interior space of the metal sheath with an insulating material, which is preferably in the form of a powder or granular material; and of compacting this insulating material at least in some sections, at least in the area of the contact points. It is especially advantageous here if the electric heating element is designed as a coil body on which a heating wire is wound, and in which holes, preferably two holes, are arranged, into which the ends of the heating wire are inserted and received, wherein the holes are large enough to permit the insertion of a part of the section of the plug contact or of an auxiliary wire crimped or welded to this section, which respective section can be arranged in the metal sheath. The compaction after the insertion of these sections will then ensure the electric contact.
The plug contact may optionally be extrusion-coated before or after the compaction, so that a plug housing surrounding the plug contact or the plug contacts is formed. This leads to a manufacturing process for manufacturing an electric heater with a plug, which heater can be manufactured in an especially small number of steps rapidly and in a cost-effective manner.
It is also possible, in cases in which a plurality of plug contacts are provided, to provide these such that they are at first connected to one another and are separated only later, especially at the end of the process. This has the advantage that the insertion of a plurality of plug contacts is made possible in a single operation.
In another preferred embodiment of the process, the shaping of the contact sections of the plug contacts is carried out only after establishing an electric connection to the heating element. This may be carried out especially by stamping out the contacts. It is often necessary in practice to provide heaters with a standardized heat output, which heaters must be provided with adapted terminals each for use in a number of different devices. The need to manufacture a particular individual series for this can be avoided with the procedure thus described, and a standard assembly unit can be manufactured, instead, optionally also for stocking, which is then provided with the desired contacts and optionally with adapted extrusion-coated housings in a finishing step.
The present invention will be explained in more detail below on the basis of figures, which show exemplary embodiments of the present invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
Referring to the drawings, identical components of the same exemplary embodiments are designated below by identical reference numbers.
Furthermore, two plug contacts 108, 109 are seen, which have, on the terminal side, an integrally molded contact tongue 108a, 109a each and a section 108b, 109b each arranged in the interior space 103 of the metal sheath 101. The end 108c, 109c of the plug contact 108, 109 located opposite the terminal side is inserted into a respective hole 105 and 106, respectively.
The dotted section in the area of the interior space 103 indicates that this area is filled with an insulating material filling consisting of a powder or granular material, which filling is compacted especially in the area of the metal sheath 101 in which the coil body 104 is located. The sections of the heating wire coil 107 and of the plug contacts 108c, 109c, which are received in the respective holes 105 and 106, are brought into conductive contact with one another by this compaction, so that contact points 110, 111, at which the heating wire coil 107 and sections 108c, 109c are conductively connected to one another, are formed.
The electric heater 200 according to
The electric heater 300 according to
The electric heater 400 shown in
The plug housing 414 has a section 414a, which is dimensioned such that it can be inserted into the terminal-side end area of the metal sheath 401 with the bottom 402 and can be fixed there by pressing.
The exploded view in
It is only necessary to insert the coil body 404 with the heating wire coil 407 arranged on it into the interior space 403 of the metal sheath 401. The insulating material filling, not shown in
However, a preferred alternative comprises the partial insertion of the sections of the plug contacts 408, 409, which shall be received in the holes 405, 406, into the holes 405, 406 before the filling before filling the metal sheath 401 (which may, in principle, also take place already when the coil body 404 is not yet inserted into the interior space 403 of the metal sheath 401, in which case the components thus preconfigured are inserted together into the metal sheath 401), after which the filling with the insulating material, not shown, is carried out, and the plug assembly unit is finally pushed a bit further into the interior space 403 of the metal sheath 401, so that the section 414a of the plug housing 414 is received at least partially in the metal sheath 401.
The electric contact between the plug contacts 408, 409 and the heating element 407 can then be established in a subsequent compaction step together or sequentially, the insulating material filling can be compacted, and the firm, non-positive and/or positive-locking seating of the plug housing 414, designed as an angle plug here, in the metal sheath 401 can be achieved.
As a result, a heater 400 comprising a small number of components with integrated plug is obtained, in which contact problems between individual components are extensively avoided.
The fifth embodiment of a heater 500, which is shown as an exploded view in
The plug contacts 508, 509 have a heating coil contact section 508c, 509c each, which are inserted in the assembled state into holes 505, 506 in the coil body 504 and establish the contact with the heating wire coil 507 within the coil body 504. Furthermore, they have a guide section 508b, 509b, which is received in the ducts 516, 517 in the assembled state and is guided there. At the plug-side end, the plug contacts 508, 509 are provided with contact tongues 508a, 509a each. The guide section 508b, 509b is made broader or thickened compared to the heating coil contact section 508c, 509c, so that a stop 508d, 509d each is formed at the transition between the guide section 508b, 509b and the heating coil contact section 508c, 509c. If such a stop, which may also be formed in another manner and is also advantageous in itself without the additional features of the exemplary embodiments according to
Furthermore, a plug housing 518 is provided, which has a connection section 518a and a plug housing section 518b and is preferably extrusion-coated around the plug contacts 508, 509, so that at least parts of the contact tongues 508a, 509a are received in a cavity, which adjoins the terminal-side end face of the plug housing 518 and into which a counterplug can be inserted.
To assemble the heater 500, a metal sheath 501 is provided, which is provided with a bottom 502 and into which the coil body 504 on which the heating wire coil 507 is wound and the ceramic tube 515 are inserted. The length of the coil body 504 and of the ceramic tube 515 is preferably selected to be such that when these are brought into their end position in the metal sheath 501, they adjoin each other. Furthermore, the terminal-side boundary surface of the ceramic tube 515 preferably also presets in this position the desired filling height of the insulating material filling, which is subsequently filled in. It is guaranteed thereby that the plug contacts 508, 509, around which the plug housing 518 is extrusion-coated, can be inserted in the next step in a simple manner.
The metal sheath 501 advantageously protrudes on the terminal side over the ceramic tube 515 if a plug housing 518 is provided with a connection section 518a, whereas it may be advantageous in the embodiments without such a connection section 518a or entirely without a plug housing 518 but with an additional ceramic tube 515 if the metal sheath 501 and the ceramic tube 515 end in the same plane on the terminal side in the assembled state. Such a protrusion makes it possible to fix the plug housing 518 with the connection section 518a in the metal sheath 501 during the pressing of the insulating material filling, which is necessary anyway and which also ensures the electrical contact between the heating wire coil 507 and the plug contacts 508, 509.
The contact between the plug contacts 608, 609 and the auxiliary wires 612, 613 is established here by inserting the ends of the plug contacts 608, 609, which ends face the coil body, and the terminal-side ends of the auxiliary wires 612, 613 into holes 621, 622 of a small ceramic tube 623 in such a way that they overlap each other and by bringing them then into contact with one another by pressing. Contacting by pressing is especially advantageous in case of low-voltage applications, because the effects of contact resistances can thus be reduced. In addition, welding of auxiliary wires 612, 613 and plug contacts 608, 609 may optionally be performed.
To obtain an operable electric heater, the plug contacts 708, 709 will then have to be separated from one another in a later process step, which may be carried out especially at the end of the manufacturing process, by removing the connection piece 710.
Additional advantages arise if, instead of manufacturing the preliminary stage according to
The electric heater 850 manufactured according to this stamping step is shown in
As a result, it becomes possible, on the one hand, not only to insert all plug contacts in one process step, while, on the other hand, the plug contacts 808, 809 stamped later are positioned accurately in relation to one another and they especially protrude from the metal sheath 801 by exactly the same amount, but the corresponding assembly unit can be manufactured by mass production and can then be easily adapted to the requirements of different customers or use environments by a final second stamping step.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 109 720 | Jul 2014 | DE | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3466426 | Kefauver, Jr. | Sep 1969 | A |
| 3492624 | Oakley | Jan 1970 | A |
| 20130056456 | Schlipf | Mar 2013 | A1 |
| Number | Date | Country |
|---|---|---|
| 102984834 | Mar 2013 | CN |
| 203136207 | Aug 2013 | CN |
| 20 2011 105 348 | Dec 2011 | DE |
| Number | Date | Country | |
|---|---|---|---|
| 20160014844 A1 | Jan 2016 | US |
