This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 20 2007 007 270.8 filed May 22, 2007 and German Patent Application DE 20 2007 008 404.8 filed Jun. 25, 2007, the entire contents of each of which are incorporated herein by reference.
The present invention pertains to a heating cartridge, especially a thermostatic working valve, with a resistance wire winding, which is wound on a winding support and is embedded in an insulating material filling in a metal sheathing, which is provided at one end with a dimensionally stable coupling element, which is manufactured from a plastic and in which connecting lines are arranged, which electrically connect pluggable contact elements, especially pins of a connector plug, to the ends of the resistance wire winding.
In a heating cartridge of this type (DE 203 08 941 U1), the metal sheathing is provided at one end with a flange, which is directed all round radially outwardly and which is directly embedded in the holder consisting of an injection-molded plastic part and is preferably fitted together with same during the shaping thereof, i.e., during the injection molding operation, to form one assembly unit. The electrical connecting lines are also embedded in the body of the holder and connected in the process to the plug contacts of a plug extending at right angles to the axis of the heating cartridge.
Aside from the fact that the extrusion coating of the flange leads to a larger outside diameter of the holder in this area, it cannot be avoided that a part of the metal sheathing must be extrusion coated as well. This means that the holder requires much space in the area of the end section of the metal sheathing, which space is not available in some applications.
A tubular heating element with a metal sheathing, in which the open end of the metal sheathing is closed by a closing plug consisting of an insulating material, is known from DE 31 17 069 C2. A winding support made of a ceramic material, which is provided with the heating coil and is surrounded by granular insulating material in the metal sheathing, has two axial holes, in which contact pins, which are in contact with the lead-out wires, are accommodated. These contact pins pass through two holes of the closing plug such that the ends of the contact pins close flush with the outer front surface of the closing plug. The blank ends of connecting lines are introduced for contacting into front-side axial holes, which are radially offset by about half the diameter of the contact pins in relation to the contact pins. The contacting fastening of these connecting lines is brought about by radial pressing of the metal sheathing in the area of the closing plug. The end of the metal sheathing, which is tapered by pressing, may be provided with an additional sleeve, optionally with an additional closing piece. However, a coupling element with pluggable contact elements is not provided for in this tubular heating element.
The basic object of the present invention is to provide a heating cartridge of the type mentioned in the introduction in an easy-to-carry-out manner with a holder, which is preferably combined with a connector plug, which requires little space in the end area of the metal sheathing both radially and vertically and otherwise simplifies handling and optimizes the possibilities of application and use of the heating cartridge.
This object is accomplished according to the present invention by the connecting lines being rigidly seated in the coupling element, by the coupling element being designed as a connector plug and/or holder and having a connection section, which protrudes into the open end of the metal sheathing and which is fastened in the metal sheathing by preferably radial pressing in a non-positive and/or positive-locking manner and forms a dimensionally stable structural unit with same.
Depending on the particular application, it may be expedient and advantageous if the connector plugs and the holder form a one-piece injection-molded part.
A connection cable or other connections between the holder and the connector plug may now be eliminated.
The possibilities of use and application are greatly expanded and improved because of the smaller space requirement with the type of connection according to the present invention between the holder and the heating cartridge. In addition, this connection can also be manufactured more easily and reliably because a centered fastening of the metal sheathing of the heating cartridge, which metal sheathing is provided with the holder, can be prepared in a press mold in a simpler manner, i.e., with a reduced technical effort. It is, above all, of considerable advantage that the insertion of the metal sheathing equipped with the winding support and the heating coil and filled with the granular insulating material into an injection mold is eliminated.
Other advantageous embodiments are disclosed with the embodiment having the ends of the connecting lines mechanically connected to the winding support to form an assembly unit that can be handled uniformly before insertion in the metal sheathing, considerably facilitating mounting.
As is shown by the exemplary embodiments described below, the present invention can be embodied in at least four different ways:
The coupling element, which also forms the upper closure of the heating cartridge and contains the electrical connection parts, may be designed 1) as a connector plug only, 2) as a holder only, 3) as a combined connector plug with a holder or 4) as a holder, which is connected by an electrical cable to a connector plug.
The present invention will be explained in more detail below on the basis of the drawings. 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:
a is a 3D view of the coupling element according to
b is a 3D view of the coupling element and the winding support as an assembly unit that can be handled uniformly;
a is a 3D view of the holder as an individual part with electrical connection parts;
a is a 3D view of the coupling element according to
Referring to the drawings in particular, a heating cartridge 1 shown as an example in the drawings comprises a resistance wire winding 3 wound on a cylindrical winding support 2. The winding support 2 consists of an electrically non-conductive material, for example, ceramic, and it has at least one hole 4, which extends continuously axially and through which the lower end of the resistance wire winding 3 can be passed upwardly.
The winding support 2 with its resistance wire winding 3 wound upon it is embedded in an insulating material filling 5, which may consist, for example, of a metal oxide, preferably magnesium oxide, and which is located in a metal sheathing 7 closed at the lower front side 6.
A coupling element 8, which is manufactured from an injection-molded plastic and is designed as a connector plug 8/1 in the embodiment according to
The pins 9 and 10 are provided, moreover, with thickened foot parts 13, which have a rectangular cross section and with which they are embedded in the body of the coupling element 8 or of the connector plug 8/1. In other words, these foot parts 13 and the lower section of the two pins 9 and 10 are completely extrusion-coated, so that they have a stable position.
The foot parts 13 of these pins 9 and 10 are provided on the underside with axially parallel holes 14 each, into which the upper ends 15 and 16, respectively, of two connection wires 17 and 18 of the resistance wire winding 3 are plugged in a contacting manner. This contacting of the wire ends 15 and 16 with the foot parts 13 of the pins 9 and 10 may be embodied by non-positive connection (pressing) and/or connection in substance (soldering, welding).
Instead of such connection wires 17 and 18, it is also possible to provide any other, suitable type of connection as an electrical connection between the resistance wire winding 3 and the pins 9, 10. Thus, the pins 9, 10 with their foot parts 13 and the connection wires 17, 18 may also be of a one-piece design and made, for example, of a punched part.
In other words, the pins 9, 10 may, however, also be provided, if they are manufactured, for example, in a suitable punching and embossing process, with electrical connection pieces, which are made integrally in one piece with them and via which they are connected to the lead-out wires.
The connecting line may also consist as a two-part line from two non-sheathed parts, which are welded or soldered to one another.
The connection wires 17 and 18 may be provided with an insulating jacket 19 over their length extending between the winding support 2 and the foot parts 13, which is, however, not absolutely necessary, because it is surrounded by insulating materials anyway.
While the connection wire 17 is connected to the upper end 20 of the resistance wire winding 3, the connection wire 18 within the hole 4 of the winding support 2 is in electrically conductive connection with the lower end 21 of the resistance wire winding 3. It is advantageous in this connection to provide in the winding support 2 a second through hole 4, in which the lower end of the connection wire 17 and the connection thereof to the upper lead-out wire 20 is accommodated.
A mechanical connection is also established between the coupling element 8 and the winding support 2 by the lower ends of the connection wires 17, 18, which are introduced into the holes 4 of the winding support 2 at least with a perceptible tensioned seat, so that the winding support 2 can be easily introduced into the metal sheathing 7 in terms of manufacturing technology by the winding support being guided at the coupling element.
As is shown in
As is apparent especially from
The coupling element 8 may be designed, according to
As is shown in
As is shown in
Independently from these possible embodiments of the coupling element as a connector plug 8/1, as a holder 8/2 or as a combination of a connector plug 8/1 and a holder 8/2, the connection element is provided in all embodiments with a connection section 28, which protrudes into the upper, open end of the metal sheathing 7 and is fastened in the metal sheathing 7 of the heating cartridge 1 in a non-positive manner by preferably radial pressing. As is shown by the exemplary embodiments shown, this connection section 28 may have various designs, e.g., in the form 28a, 28b or 28c, and fastened in the metal sheathing 7 in different ways.
Thus, a reliable, rigid and stable connection can be guaranteed between the coupling element 8, on the one hand, and the heating cartridge 1 or the metal sheathing 7 thereof, on the other hand.
The winding support 2 with the winding 3 and with the connection wires 17, 18 connected thereto are inserted into the metal sheathing 7 together with the connection section 28a, 28b, 28c. The powdered insulating material filling 5 is introduced simultaneously or later and slightly compacted at first by shaking, so that no cavities will remain. To avoid contact between the resistance wire winding 3 and the metal sheathing 7 with certainty, the inner surface of the metal sheathing 7 may have a sleeve made of insulating material or a wound film made of insulating material at least in the axial area of the resistance wire winding 3.
As is apparent from
In another embodiment according to
Just as in the embodiment according to
It is possible to fill the insulating material filling into the upper end of the metal sheathing 7 after insertion of the connection section 28a in case of both the laterally flattened cross-sectional shape according to
To attain a higher tensile strength, the upper end of the metal sheathing 7 is provided with a circumferential, inwardly projecting ring bead 23, so that there also is a positive-locking connection with the narrow sides of the connection section 28a in addition to the non-positive connection or the connection in substance.
Such a ring bead 23 is also recommended in the embodiment according to
It is clearly recognizable from the drawings that a very slender, radially only slightly projecting three-dimensional shape is obtained in case of such an embodiment of the coupling element 8.
Depending on the embodiment, the radial pressing of the heating cartridge and hence the compaction of the insulating material filling may be carried out before or after the embedding of the coupling element 8 by injection molding with one of the connection sections 28a, 28b or 28c.
Depending on the type of use and the specifications for installation, the connection sections 28 may be provided with a greater axial length than shown in order to achieve an even more stable connection to the metal sheathing 7.
In the exemplary embodiment being shown, holder 8/2 has a cylindrical shape with an annular groove 33 located between two movable flanges 31, 32. A connection part 35 of cable 30, which connection part consists of an elastic insulating material and is provided with a ring lip 36 extending elastically behind the bead 34 in a positive-locking manner for this purpose, is fastened to a front-side central bead 34 of holder 8/2.
A cable connector 37, by which the connection wires 17, 18 led through the holder 8/2 are electrically connected to the conductors 17′ and 18′ of the cable in a suitable manner, is located in connection part 35.
Connector plug 8/1 has a shape similar to that in the embodiment according to
It shall be pointed out that the outer shape of both the connector plug 8/1 and of the holder 8/2 is freely selectable and is by no means bound to the shape of the exemplary embodiments shown. For example, the connector plug 8/1 may be arranged such that it extends at right angles or obliquely to the axis 11 of the heating cartridge 1 and of the holder 8/2.
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 |
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20 2007 007 270 U | May 2007 | DE | national |
20 2007 008 404 U | Jun 2007 | DE | national |
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Number | Date | Country | |
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20080290085 A1 | Nov 2008 | US |