Abstract:
A high-temperature plug ( 10 ) is provided for a heating element and/or thermocouple or a temperature sensor with at least one wire section ( 18 ) embedded in an insulating manner within a metal jacket ( 16 ) with a wire end ( 14 ) led out from the metal jacket ( 16 ) on the front side. The high-temperature plug ( 10 ) has a connection sleeve ( 11 ) made of metal, into which the at least one wire section ( 18 ) embedded in an insulating manner within the metal jacket ( 16 ) opens. At least one contact element ( 12 ) is in electrical contact within the connection sleeve ( 11 ) with the wire end ( 14 ) led out from the metal jacket ( 16 ) on the front side. At least the end section, facing the at least one wire end ( 14 ), of the at least one contact element ( 12 ) is embedded in an insulating compound ( 13 ) or a metal oxide, such that the embedding fixes the contact element ( 12 ) in the connection sleeve.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 20 2009 011 860.6 filed Sep. 2, 2009, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a high-temperature plug as it is used especially on heating elements and/or thermocouples or temperature sensors, and a heating element and/or thermocouple as well as a temperature sensor with such a high-temperature plug. 
       BACKGROUND OF THE INVENTION 
       [0003]    Only a few of the plurality of prior-art patch plugs are suitable for high-temperature applications, in which the plugs are exposed to a thermal load of 120° C. and higher. Especially problematic is the use of plastic inserts that are often used at lower temperatures to electrically insulate the outer surface of the plug and the individual poles against one another and to fix them to one another in a preset position. 
         [0004]    High-temperature plugs in which a connection is established for every individual pole between a contact element and a conductor and the corresponding connection is then surrounded, especially after the plug thus produced has been combined with a counterplug, with a housing made of PEEK or heat-shrinkable sleeve, which said housing is coordinated with the conductor cross section and the external diameter of the individual conductor and is crimped with same and is thus thermally and electrically insulated, are known. High-temperature plugs of this type are available, e.g., from Electrolux under the name “high-temperature plug-in connection HTC.” 
         [0005]    The drawback of this embodiment is that the manufacture of a plug-in connection is associated with a relatively great effort. Furthermore, the space requirement is relatively high, especially for multipole high-temperature plug-in connections, which are based on these plugs. 
         [0006]    There is also a need for a high-temperature plug in the cleaning of plastic spray nozzles extrusion coated or sprayed over with plastic, on which a heating element is mounted, by furnace application at temperatures of, for example, higher than 300° C. 
       SUMMARY OF THE INVENTION 
       [0007]    The object of the present invention is therefore to make available a high-temperature plug that is compact and can be manufactured in a favorable manner, as well as heating elements and/or thermocouples, as well as temperature sensors with such a high-temperature plug. 
         [0008]    This object is accomplished by a high-temperature plug, by a heating element, by a thermocouple and by a temperature sensor having the features having the features according to the invention. 
         [0009]    The high-temperature plug according to the present invention for a heating element and/or thermocouple or a temperature sensor with at least one wire section embedded in an insulating manner within a metal jacket with a wire end led out from the metal jacket on the front side, has a connection sleeve made of metal, into which the at least one wire section embedded in an insulating manner within a metal jacket opens. At least one contact element is in electrical contact within the connection sleeve with the wire end led out from the metal jacket on the front side. 
         [0010]    According to the present invention, at least the end section, facing the at least one wire end, of the at least one contact element is embedded in an insulation compound or a metal oxide, such that the embedding fixes the contact element in the connection sleeve. 
         [0011]    In terms of this invention, an insulation compound is defined especially as a ceramic insulation compound, an epoxy resin, a silicone rubber, at least one ceramic molding or one ceramic cement compound. 
         [0012]    In this case, fixed means that the position of the contact elements in relation to one another and in the connection sleeve is fixed. 
         [0013]    The present invention is based on the discovery that an insulation compound or a metal oxide may not only offer a good thermal insulation, but also take over electrical insulation of the individual poles and of the housing formed by the connection sleeve at least in sections as well as the fixing of the poles and of the housing in relation to one another. This multifunctional use of an insulation compound or metal oxide would make possible a simple design that can be manufactured in a fast manner, which is, moreover, overall compact as well. 
         [0014]    The design is especially simple when at least the end section, facing the at least one wire end, of the at least one contact element is embedded in an insulation compound or a metal oxide, such that the embedding fixes the contact directly in the connection sleeve. A direct fixing is present when the preset position is guaranteed alone by the interaction between the connection sleeve, insulation compound and the embedded section of the contact element. By contrast, if the contact elements are embedded in a plastic sleeve to fix the position of the contact elements in relation to each other and then the position of the plastic sleeve is fixed within the connection sleeve, the fixing is no longer direct, but only indirect. 
         [0015]    It proved to be especially advantageous in particular for the desired fixing of the contact elements when the insulation compound or the metal oxide fills up the space between the contact element and/or the wire end and connection sleeve in any direction running at right angles to the plugging direction. In other words, at least in the contact area the entire cross section of the connection sleeve is filled up with ceramic insulation compound or a metal oxide in this embodiment. 
         [0016]    An especially simple design of the high-temperature plug is achieved when the entire volume of the connection sleeve is filled up with ceramic insulation compound or metal oxide in the plugging direction in the area between the contact area and the metal jacket, insofar as it is not filled up by the at least one contact element and the at least one wire end. 
         [0017]    The manufacture of the high-temperature plug is especially simple, if the insulation compound or metal oxide is a porous material compressed with the connection sleeve by reduction of the cross-sectional area. In this case, a metal oxide powder can be charged into the connection sleeve up to the desired height and subsequently compressed, e.g., after pushing a connection sleeve onto the metal jacket, which abuts closely against same, to achieve the desired fixing and insulating action. Another possibility lies in pushing at least one molding made of insulation compound or of metal oxide onto the contact element and the wire end. 
         [0018]    To improve the tightness of a plug embodied in this manner, e.g., against penetration of water, it is possible to provide, on the plug side on the compressed insulation compound or the compressed metal oxide, a layer of ceramic insulation compound, an epoxy resin, a high-temperature plastic, which is stable at a long-term thermal load of 180° C. or higher, or silicone rubber. 
         [0019]    The highest temperature resistance and highest stability or best fixing of the high-temperature plug are obtained when a porous ceramic insulation compound or a metal oxide is highly compressed in the connection sleeve or when the connection sleeve is filled or cemented with ceramic insulation compound. The use of a ceramic cement compound here as the insulation compound is especially advantageous because of the simple manageability. 
         [0020]    As contact elements for the high-temperature plug, contact pins or flat plugs offer the special advantage that in this embodiment, after separating a connection of the high-temperature plug with a counterplug without previous interruption of the operating voltage, the freely accessible male contact elements are not live. Of course, however, the use of bushings or a combination of contact pins or flat plugs and bushings is also possible. An especially suitable material for the contact elements is steel, especially spring steel because of its thermal properties and the high elasticity needed for high contact pressures. 
         [0021]    Furthermore, it is advantageous when the contact elements in the plug-side direction project above the tube opening of the connection sleeve. Thus, it is possible to arrange still live countercontacts integrated in a housing after separating a connection of a high-temperature plug with a counterplug without previous interruption of the operating voltage. As an alternative, however, the contact elements may also be embedded in the insulation compound or the metal oxide only with the non-pluggable area and be projected from the tube opening of the connection sleeve in the plugging direction. 
         [0022]    It is especially advantageous to provide a firm connection between the connection sleeve and the metal-jacketed end, which can especially be achieved by means of pressing, welding or soldering the connection sleeve onto the metal-jacketed end. Depending on the geometry of the application, it may, however, also be favorable to prepare such a connection by means of additional spacers, e.g., to achieve a gradual widening of the diameter. 
         [0023]    An advantageous embodiment of the high-temperature plug provides for at least one wire end to be in electrical connection with a hot wire coiling or a heating circuit or heating layer of a heating element. 
         [0024]    With the high-temperature plug, especially compact connections can be established when a metal-jacketed end of a heating element and an end of the jacketed thermometer in a common connection sleeve are combined into a common multipole plug or when a plurality of heat circuits in a connection sleeve are combined into a multipole plug. 
         [0025]    For arrangements comprising a jacketed thermometer, it is advantageous if the high-temperature plug has at least two wire ends of the jacketed thermocouple, which are made of the materials of the pair of thermocouples. 
         [0026]    The compactness of the connection is especially advantageous when the wire ends of a plurality of different heating elements or thermocouples in a single high-temperature plug are combined into a multipole plug. 
         [0027]    Furthermore, an arrangement, in which the wire ends of a heating element and of a thermocouple integrated in the heating element open into a multipole plug, so that only a single high-temperature plug has to be used for connecting the entire arrangement, is advantageous. 
         [0028]    For the fixation of a plug-in connection formed by using the high-temperature plug, it is favorable when the connection sleeve has at least one recess or at least one bead, which makes possible a locking with a housing of a counterplug. 
         [0029]    In an advantageous embodiment of the high-temperature plug, the connection sleeve forms at least a part of a plug housing. In particular, the design of the high-temperature plug is especially simple if the connection sleeve forms the plug housing at the same time. As an alternative, the connection sleeve or plug housing may, however, also consist of a plurality of parts. 
         [0030]    The heating element according to the present invention has at least one metal-jacketed connection line or at least one metal-jacketed end, in which at least one wire section which is embedded in an insulating manner within a metal jacket with a wire end led out from the metal jacket on the front side is present, and a high-temperature plug in an above-described embodiment. It is particularly especially compact and can be connected in a simple manner. 
         [0031]    The heating element has an especially advantageous design if the metal-jacketed end is part of the unheated end of the heater or if the metal-jacketed end is a component of a jacketed thermometer. 
         [0032]    An embodiment of the heating element that is especially advantageous with regard to insulation of the metal-jacketed end provides that the metal-jacketed end is mineral-insulated. Furthermore, it is advantageous when the wire section in the metal-jacketed end or in the metal-jacketed line is insulated by a glass fabric, a quartz fabric, a polyimide or by mica. 
         [0033]    The thermocouple according to the present invention has at least one metal-jacketed connection line or at least one metal-jacketed end, in which at least one wire section which is embedded in an insulating manner within a metal jacket with a wire end led out from the metal jacket on the front side is present, and a high-temperature plug in an above-described embodiment. In particular, it is especially compact and can be connected in a simple manner. 
         [0034]    An embodiment of the thermocouple that is especially advantageous with regard to insulation of the metal-jacketed end provides that the metal-jacketed end is mineral-insulated. Furthermore, it is advantageous when the wire section in the metal-jacketed end or in the metal-jacketed line is insulated by a glass fabric, a quartz fabric, a polyimide or by mica. 
         [0035]    The temperature sensor according to the present invention has at least one metal-jacketed connection line or at least one metal-jacketed end, in which at least one wire section embedded in an insulating manner within a metal jacket with a wire end led out from the metal jacket on the front side is present, and a high-temperature plug in an above-described embodiment. In particular, it is especially compact and can be connected in a simple manner. 
         [0036]    An especially advantageous embodiment of the temperature sensor is present if the temperature sensor is a platinum measuring resistor or an NTC. 
         [0037]    An embodiment of the temperature sensor that is especially advantageous with regard to insulation of the metal-jacketed end provides that the metal-jacketed end is mineral-insulated. Furthermore, it is advantageous when the wire section in the metal-jacketed end or in the metal-jacketed line is insulated by a glass fabric, a quartz fabric, a polyimide or by mica. 
         [0038]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    In the drawings: 
           [0040]      FIG. 1  is an end view of a single-pole exemplary embodiment of a high-temperature plug, viewed against the plugging direction; 
           [0041]      FIG. 2  is a sectional view of the exemplary embodiment from  FIG. 1 , cut along line C-C of  FIG. 1 ; 
           [0042]      FIG. 3  is another sectional view of the exemplary embodiment from  FIG. 1 , cut along line B-B of  FIG. 1 ; 
           [0043]      FIG. 4   a  is a side view of a plug-in connection with a counterplug produced by using the high-temperature plug shown in  FIGS. 1 through 3 , viewed at right angles to the plugging direction; and 
           [0044]      FIG. 4   b  is a sectional view showing the plug-in connection from  FIG. 4   a , viewed along line A-A of  FIG. 4   a.    
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0045]    Referring to the drawings in particular, in all figures identical reference numbers are used for identical components of identical exemplary embodiments. 
         [0046]      FIG. 1  shows the view of a single-pole exemplary embodiment of a high-temperature plug  10 , viewed against the plugging direction. Of course, it is also possible to build multipole, especially two- and four-pole plugs according to the principle of the present invention. Viewed from inside to outside, a contact element  12  with a section with square cross section  12   b , insulation compound  13 , connection sleeve  11  and an optional second connection sleeve  20 , which is in the form of a square with rounded corners, on one side of which a tongue  21  with a recess  22  is integrated, are recognized. The lines B-B and C-C represent intersecting lines that illustrate the perspectives of the views of  FIGS. 2 and 3 , from which the design of the high-temperature plug  10  emerges more clearly. 
         [0047]      FIG. 2  shows a sectional view of the exemplary embodiment from  FIG. 1 , cut along line C-C. A metal-jacketed connection line  19 , consisting of a wire section  18 , which is surrounded by an insulating embedding  17  and a metal jacket  16  at right angles to its direction of extension, is recognized. A wire end  14  projects in the plugging direction from the front surface of the metal-jacketed connection line  19 . 
         [0048]    The end section of the metal-jacketed connection line  19  is surrounded by a connection sleeve  11  made of metal, which is firmly connected to the metal jacket  16 , at right angles to the direction of extension of the metal-jacketed connection line  19 . The connection sleeve  11  extends out in the plugging direction over the end of the metal-jacketed connection line  19 . 
         [0049]    In a contact area  15  the wire end  14  is in contact with a contact element  12 , which is designed here as a contact pin with a bore, which, however, cannot be seen in  FIG. 2 , because it is filled up by the plug-side end section of the wire end  14 . The contact element  12  projects over the connection sleeve  11  in the plug-side direction. The area between contact element  12  or wire end  14  and the part of the connection sleeve  11  extending out in the plugging direction over the end of the metal-jacketed connection line  19  is filled up with a ceramic insulation compound  13 . A filling with a metal oxide would likewise be suitable. By means of the filling, the exact positioning of the contact element  12  is fixed, on the one hand, and the thermal and electrical insulation to connection sleeve  11  is guaranteed, on the other hand In the exemplary embodiment shown, not only is the contact area  15  embedded in the insulation compound, but also other areas of the wire end  14  and of the contact element  12 , which makes the production of the high-temperature plug  10  especially simple. 
         [0050]    To a plug-side section of the connection sleeve  11 , a second sleeve  20  made of metal surrounding same in a direction at right angles to the plugging direction is fastened, which extends out in the plugging direction both over the connection sleeve  11  and over the plug-side end of the contact element  12 . Even though a strong holding force is exerted between the high-temperature plug  10  and a counterplug especially when using contact elements made of steel even at high temperature, a securing of the plug-in connection by means of the second sleeve  20  is advantageous. This securing is made possible by a section of the wall of the second sleeve  20  not adjacent to the connection sleeve  11  being designed as a tongue  21 , which has a recess  22 . As described in more detail below based on  FIGS. 4   a  and  4   b , a locking connection between the high-temperature plug  10  and a counterplug is consequently made possible. The plug-side edge of the second sleeve  20  is advantageously bent slightly outwards, i.e., in a direction at right angles to the plugging direction to form an insertion aid for the counterplug. 
         [0051]      FIG. 3  shows another sectional view of the exemplary embodiment from  FIG. 1 , cut along line B-B. The design which is disclosed in  FIG. 3  corresponds in full to the design described in detail based on  FIG. 2 ; to avoid repetitions, reference is made explicitly to the description of  FIG. 2 , and only additional, recognizable details are dealt with. In this section, crimp points are shown as circles in the contact area  15  to illustrate that contact element  12  and wire end  14  are fastened to one another. Furthermore, the tongue  21  cannot be seen in this section; however, it is more clear that the recess  22  breaks through the second sleeve  20 . 
         [0052]      FIG. 4   a  shows the view of a novel plug-in connection with a counterplug  50  produced using the high-temperature plug  10  shown in  FIGS. 1 through 3 , viewed at right angles to the plugging direction. Of the high-temperature plug  10  only metal jacket  16  of the metal-jacketed connection line  19 , connection sleeve  11  and second sleeve  20  with tongue  21  and recess  22  can be seen in this view. Of the counterplug  50 , a connection line  60 , a part of a housing  51  not overlapped by the second sleeve  20  and a detent  52 , which is arranged at the housing  51  and which meshes with the recess  22 , can be seen. Details of the design can be derived from the sectional view along the line A-A, which is shown as  FIG. 4   b.    
         [0053]    The high-temperature plug  10 , which is shown in  FIG. 4   b , is exactly identical to the high-temperature plug shown in  FIG. 3 ; hence, for its design reference is made to the description of  FIG. 3  and the description of  FIG. 2  included therein. The counterplug  50  has a housing  51  with a one-piece design that is preferably made of ceramic or a high-temperature-resistant plastic. The detent  52  of the housing  51  already described in  FIG. 4   a  is locked with the recess  22  in the tongue  21  of the second sleeve  20  and thus prevents an undesired detachment of the plug-in connection. 
         [0054]    Furthermore, the housing  51  has a passage opening  57  and a duct opening  65  on the plug side and an insertion opening  63  on the side opposite the plugging side. The passage opening  57  and the insertion opening  63  are connected to one another via an interior  59  of the housing  51 . The duct opening  65  is likewise connected to the interior  59  via a duct  56  that is open towards the interior  59  and runs parallel to the plugging direction. The end surface of the duct  56  formed by the wall of the housing  51 , facing away from the plugging side, leads to the formation of a locking step  53 . A contact element  64 , which can be pushed through the insertion opening  63 , which is designed here as a bushing with clamping legs  54 ,  58  and a mounting area  62  and is preferably made of steel and especially spring steel, is inserted into the interior  59 . A stop spring  55 , which is locked with the locking step  53 , is arranged at clamping leg  58 . The contact element  12  of high-temperature plug  10 , which is designed as a contact pin, is clamped between the clamping legs  54 ,  58 . A reliable electrical and mechanical contact between the respective contact elements  12 ,  64  is guaranteed by the high pressure of the clamping leg, which is made possible by the use of steel as a material for the contact elements even at high temperatures. 
         [0055]    In the mounting area  62  of the contact element  64 , electric contact is made with an exposed inner conductor  61  of a connection line  60  inserted into the housing  51  a little way through the insertion opening. 
         [0056]    This novel combination of high-temperature plug  10  and counterplug  50  makes possible an up to now unknown, very simple and comfortable procedure in the production of the plug-in connection. After the high-temperature plug is prepared, only a piece of the inner conductor  61  on the plug-side end of the connection  60  still has to be exposed, which is then brought into electrical contact with the contact element  64  of the counterplug, e.g., by crimping or soldering. The connection line thus connected to the contact element  64  must then only be pushed through the insertion opening  63  of the housing  51  until the stop spring  55  locks with the locking step  53 . Thus, contact element  64  of the counterplug  50  is fixed between locking step  53  and the plug-side wall of housing  51  and the counterplug is already mounted. To complete the plug-in connection, only the housing  51  still has to be pushed into the second sleeve  20  of the high-temperature plug  10  until the detent  52  locks into the recess  22 . Then at the same time, the contact element  12  of the high-temperature plug  10  is brought into electrical connection with the contact element  64  of the counterplug  50 . 
         [0057]    The detachment of the plug-in connection is likewise simple. For this, the tongue  21  of the high-temperature plug  10  is lifted, e.g., by means of a screwdriver, so that detent  52  is released. Then high-temperature plug  10  and counterplug  50  can be pulled apart. In the same way, it is possible to push back the stop spring  55  of the contact element  64  by inserting a correspondingly shaped object through the duct opening  65  into the duct  56  and consequently make possible the pulling out of the contact element  64 . 
         [0058]    Basically, instead of the second sleeve  22 , the connection sleeve  11  of the high-temperature plug  10  may be embodied, such that it projects over the contact element  12  in the plugging direction and has a tongue with a recess or a correspondingly embodied second sleeve arranged at the counterplug, which can then be brought into contact with a detent at the connection sleeve  11 . 
         [0059]    While specific embodiments of the invention have been 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. 
       APPENDIX 
     LIST OF REFERENCE NUMBERS  
       [0000]    
       
           10  High-temperature plug 
           11  Connection sleeve 
           12 ,  64  Contact element 
           12   b  Square section 
           13  Insulating compound 
           14  Wire end 
           15  Contact area 
           16  Metal jacket 
           17  Insulating embedding 
           18  Wire section 
           19  Metal-jacketed connection line 
           20  Second sleeve 
           21  Tongue 
           22  Recess 
           50  Counterplug 
           51  Housing 
           52  Detent 
           53  Locking step 
           54 ,  58  Clamping leg 
           55  Stop spring 
           56  Duct 
           57  Passage opening 
           59  Interior 
           60  Connection line 
           61  Inner conductor 
           62  Mounting area 
           63  Insertion opening 
           65  Duct opening