Abstract:
A device for connecting components ( 1, 2, 3 ) made of fusible plastic, especially pipes ( 12, 60 ) of a fuel pipeline or a fuel line to a fuel tank ( 8 ) of a vehicle. The device includes a heating element ( 4 ) having ends ( 44, 46 ) which are used to supply electrical energy. The device is easy to use, simple to mount, and produces a functionally reliable welded joint between the components ( 1, 2, 3 ). To achieve this, one component ( 3 ) includes a retaining body ( 16 ) for a retaining tool ( 50 ), and the two ends ( 44, 46 ) of the heating element ( 4 ) extend onto the retaining body ( 16 ) where they can engage contact elements ( 56, 57 ) on the retaining tool ( 50 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of international patent application no. PCT/EP01/09052, filed Aug. 3, 2001, designating the United States of America, and published in German as WO 02/11973, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of German patent application no. DE 200 13,596.1, filed Aug. 4, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a device for connecting components made of fusible plastic, particularly pipes of a fuel line, or for connecting a fuel line with a fuel tank of a vehicle.  
           [0003]    European patent application no. EP 919,761 discloses a device of this type which comprises a sleeve body for connecting two pipe ends. In the inside surface of the substantially hollow cylindrical sleeve body a heating element is arranged, which is configured as a heating coil made of resistance wire and to which a current or electric energy can be applied. The wire ends of the heating element configured as a heating coil extend to the exterior into sockets. With corresponding contacts of connecting lines, the electrical connection with a welding device can be established to supply the heating element with current and thereby to heat the plastic so that an electric weld is produced.  
           [0004]    Such electric welding sleeves have been used very successfully to connect pipes in supply networks, e.g., water pipes or gas pipes. However, the personnel must be experienced in handling the welding device and producing the electric weld, and the welding operation has to be carefully prepared and executed. Also, the production of such welding sleeves, particularly with respect to the contacting of the wire ends in said sockets is quite complex. To prepare and execute the electric welding operation, various actions must be performed manually, which involves a considerable amount of time and assembly.  
           [0005]    Especially in automotive fuel tank systems with a plastic fuel tank and a plastic fuel line that is to be connected therewith, the current joining techniques consist of using hose connecting clamps or butt-welding of the connecting points with heat reflectors. The drawback is that there is no adequate diffusion barrier and complex assembly is required during production, especially since a variety of different components are required. Also, any repair or replacement of individual components requires a substantial amount of time.  
           [0006]    In addition, there is the problem of positioning add-on devices, e.g., fuel pump, hose holder, sensors, etc. in and on the tank. The currently used butt-welding process with heat reflectors is difficult, especially in the interior of the tank and/or on surfaces that are not flat. It should moreover be noted that for diffusion reasons, all additional openings on the fuel tank should be avoided, so that the positioning of additional devices in areas of the tank that are remote and/or difficult to access requires a significant amount of time and is often not possible without an auxiliary opening.  
           [0007]    When add-on devices or other parts are butt-welded with heat reflectors in the interior of the tank, a heat reflector is brought to the welding position through the existing tank opening, i.e., the opening for the tank fitting, by means of a complex telescope mechanism in order to melt the tank wall at that point. Since the additional device cannot be carried along directly for lack of space, the heat reflector must first be withdrawn and the additional device must then be brought to the desired position. Since a properly welded joint requires a predefined welding temperature and contact pressure, process control is very difficult and costly.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, it is an object of the invention to provide a device for connecting fusible plastic components that ensures a functionally reliable welded connection of the components by simple means.  
           [0009]    It is also an object of the invention to provide a device for connecting fusible plastic components which enables connections to be made at low cost.  
           [0010]    Another object of the invention is to provide a device for connecting fusible plastic components with which preparation and production of the connection requires only a little fabrication and assembly time.  
           [0011]    A still further object of the invention is to provide a device for connecting fusible plastic components which facilitates automated production of the connection so that the production of the connection can be automated at least to a large extent.  
           [0012]    Yet another object of the invention is to provide a device for connecting fusible plastic components which enables connections to be produced in an automated production plant.  
           [0013]    These and other objects are achieved in accordance with the present invention by providing a device for connecting components made of fusible plastic, at least one of the components comprising a heating element having ends through which electrical energy can be supplied, wherein the one component further comprises a holding element for engaging a holding tool, and the ends of the heating element extend to the holding element and engage contacts on the holding tool when the holding tool is applied to the holding element.  
           [0014]    The proposed device is distinguished by its simple construction and makes it possible to produce the welded joint at low cost. The component containing the heating element is provided with a holding element which carries the particularly planar heating-element ends serving for electrical connection and which is configured for the component to be held by a holding tool. Sockets or the like to produce the connection with a welding device are not required, since contact is established via the holding element and the holding tool.  
           [0015]    The holding tool is preferably constructed as a clamp for receiving the components in preparation for the welding procedure, and during welding ensures the electric connection with the heating element through suitable contacts. The component is preferably sleeve-like and on an outer surface as well as on an inner surface contains the heating element or parts thereof. It is inserted into an annular gap between the components to be joined, one of which is configured as a sleeve and the other as a pipe end.  
           [0016]    Within the scope of the invention, the sleeve can be part of a tank or a pipe for putting fuel into a motor vehicle. This sleeve is configured as an annular section which is pulled inwardly in the area of the tank opening and which is preferably an integral part of the tank. This has the significant advantage that the connection satisfies all the requirements and specifications associated with automotive technology, particularly fuel permeability relative to the environment. An improved diffusion seal and a longitudinal interference fit between the refueling pipe and the fuel tank are ensured with a high degree of functional reliability.  
           [0017]    In an alternative embodiment, the component provided with the heating element can be configured to receive and position add-on devices, e.g., a fuel pump, hose holders, sensors, etc., on the fuel tank. In automotive technology, the proposed device provides the substantial advantage that the device and/or connection satisfy all the requirements and specifications and, in particular, reduce fuel permeability relative to the environment. In the embodiment with a fuel tank, the tank comprises the sleeve-like component in the area of the tank opening for the fitting. This sleeve-like component is configured as an annular section or sleeve that is pulled into the interior of the tank, into which the plastic refueling pipe is inserted while forming a circumferential annular gap. The component configured as the welding sleeve and containing the heating element is inserted into this annular gap.  
           [0018]    In the embodiment for connecting two pipes, particularly of an automotive fuel line, the one pipe end is configured as a sleeve into which the pipe to be connected can be inserted while forming an annular gap. The component configured as the welding sleeve and provided with the heating element is again inserted into this gap. Furthermore, the component provided with the heating element can comprise this heating element in the area of an end surface or an annular surface. The surface contour can be flat, concave, convex, etc. to correspond with the surface contour of the other component. Additional pressure means are used to generate and/or maintain the required contact pressure during the welding operation, particularly between the latter component and the other component, especially the wall of a fuel tank.  
           [0019]    The holding element of the component that contains the heating element is advantageously configured as a segment or flange such that the aforementioned holding tool can engage therewith and establish the electrical contact or the electrical connection with the heating element. The contacts of the heating element are preferably arranged opposite one another so that the electrical connection with the heating element is established when the holding tool engages and/or presses against and/or holds said component.  
           [0020]    The heating element advantageously comprises a wire and/or is configured as a winding. Furthermore, the heating element or the electrical conductor or conductors can be applied to the welding surface of said component and, in particular, can be an electrically conductive vapordeposited material, or a metal grid, or electrically conductive carbon fibers, or electrically conductive plastic or polymers. The welding energy is supplied through the heating element using electric resistance heating or induction or microwave technology.  
           [0021]    Irrespective of the corresponding configuration and the concrete embodiment of the heating element, it is important within the scope of the invention that the electrical connections and/or the wire ends or the like extend to the holding element such that the electrical connection to a welding device, which provides the voltage and/or the current required for the welding operation, is established by the holding tool, particularly by the contacts arranged in the holding tool. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which:  
         [0023]    [0023]FIG. 1 is a partial longitudinal section through a fuel tank and the refueling pipe connected therewith by a welding sleeve;  
         [0024]    FIGS.  2 - 4  are schematic representations illustrating the production of a welded joint;  
         [0025]    FIGS.  5 - 8  are representations of a further embodiment according to FIG. 4 during different process steps for producing the connection with a clamp-like holding tool;  
         [0026]    [0026]FIG. 9 is a further embodiment for connecting two pipes, particularly of a fuel line;  
         [0027]    [0027]FIG. 10 is a perspective view of the component provided with the heating element of FIG. 9;  
         [0028]    [0028]FIG. 11 is a further embodiment of a component which comprises the heating element in the area of an end face and which is used to position additional devices;  
         [0029]    [0029]FIG. 12 is a side view of the component of FIG. 11;  
         [0030]    FIGS.  13 - 16  are schematic representations for positioning the component of FIG. 11 in the interior of a tank;  
         [0031]    [0031]FIG. 17 is a further embodiment of the component with a heating element arranged on an annular surface, and  
         [0032]    [0032]FIG. 18 is a schematic representation of the component of FIG. 17 inside a fuel tank.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0033]    [0033]FIG. 1 is a longitudinal section through a first component  1 , a second component  2  and an additional component  3  that comprises a heating element  4  for connecting the first and second components  1 ,  2 . The first component  1  is configured as a sleeve that surrounds the second component while forming an annular gap  6  that receives the additional component  3 . The first component  1  forms part of a tank  8 , which is only partially shown here. It extends into the interior  10  of the tank and is configured as an annular section that is pulled inwardly in the area of the tank opening.  
         [0034]    The second component  2  is part of a pipe  12 , which is also only partially shown here and is used to fill the tank  8  with fuel. These components  1 ,  2  and  3  are made of a fusible and/or thermoplastic material, particularly polyethylene (PE). The second component  2  or pipe  12  comprises a conical section  14  that is located outside the tank  8  and forms a taper of pipe  12  toward the interior  10 .  
         [0035]    The additional component  3  comprises a collar or flange  16 , also located outside the tank, in such a way that at least in the area of its free end  18  a clearance  20  is formed. Flange  16  and/or its free end  18  is configured as a holding element for a holding tool (not shown), which can engage on the one hand with the inner surface  22  of clearance  20  and on the other hand with the outer surface  24  of holding element  16  to grasp and hold the latter. The holding element  16  as depicted is advantageously closed along its circumference. Within the scope of the invention, however, at least its free end  18  can also be configured as a segment that extends over only a portion of the circumference.  
         [0036]    The additional component  3 , hereinafter also referred to as a welding sleeve, further comprises a limit stop  26 , which ensures a defined insertion depth in the first sleeve-like component  1 . The conical or tapered configuration of section  14 , where the cone angle advantageously corresponds to that of the flange of holding element  16 , determines a defined insertion depth in tank  8  for pipe  12 . The limit stop  26  may be annularly closed along the circumference or may consist of a plurality of radially outwardly facing projections.  
         [0037]    The additional component or welding sleeve  3 , in the area of annular gap  6 , is provided with a heating element  4 , which is disposed on both the inner surface  30  and the outer surface  32  of the welding sleeve  3 . The heating element  4  on the inner surface  30  has an inner heating coil  34  and on the outer surface  32  an outer heating coil  36  made of an electrically conductive wire and/or resistance wire.  
         [0038]    The heating coils  34 ,  36  are interconnected at the end face  38  of the welding sleeve  3  by a wire part  40 . This wire part  40  is advantageously disposed in a recess  42  of end face  38  and is thus protected against external influences. Advantageously, the end face  38  comprises a plurality of such radially extending recesses  42 , so that during manufacture of heating element  4 , which consists of a single continuous heating wire, wire part  40  can easily be inserted into one of these recesses  42 .  
         [0039]    According to the invention, the ends of heating element  4  or the free wire ends  44 ,  46  of the two heating coils  34  and  36  are lead to the holding element  16  and/or its free end  18 , i.e., along the inner surface and along the outer surface thereof. It is particularly important that the wire ends and/or contacts  44 ,  46  of the heating element  4  are opposite one another. Preferably, the contacts are arranged and/or configured to be planar. The ends  44 ,  46  thus form a first and a second planar contact for heating element  4 .  
         [0040]    The ends  44 ,  46  advantageously extend over the entire circumferential area of holding element  16  or, if the holding element is configured in segments, over a predefined circumferential angle. Thus, the aforementioned holding tool can engage with the holding element  16  over a predefined circumferential angle, advantageously over the full circumferential angle of 360°, to establish the electrical connection with heating element  4 . The holding tool has additional contacts that correspond with the ends or contacts  44 ,  46  of heating element  4  to ensure the electrical connection and contacting of heating element  4  when the holding element  16  is grasped.  
         [0041]    In preparation for producing the welded joint, the additional component  3  is inserted into the first sleeve-like component  1 , with limit stop  26  defining the insertion depth. Thereafter, the second component  2  is inserted into the additional component  3 , with the conical section  14  on the correspondingly conical flange or holding element  16  likewise defining the insertion depth. Alternatively, the additional component  3  can first be pushed onto the second component  2 , and the second component  2  and the additional component  3  can then be inserted into the first sleeve-like component  1 . It should be noted here that the inside and outside diameters of the adjacent surfaces of these components are adjusted in such a way as to ensure direct contact to a large extent between the associated component surfaces, so that the necessary contact pressure can be produced during the welding operation to ensure a complete and tight electric weld without gaps over the circumference and in axial direction.  
         [0042]    As will be explained below, the holding tool, in a special embodiment of the invention, can be initially used to grasp the additional component or welding sleeve  3  by the flange  16  and/or its free ends  18 , e.g., to take it out of a supply box. By means of the holding tool the additional component  3  is then inserted into the first component  1  or the tank opening configured according to the invention. Thereafter, pipe  12  with the second component  2  is inserted into the interior of the additional component  3 , while the holding tool remains engaged with the holding element  16 .  
         [0043]    The welding device, which is electrically connected with the holding tool, is preferably furthermore configured in such a way that proper contact and/or the required configuration of heating element  4  can be verified, so that incorrect contact and/or faulty additional components  3  can be detected and can advantageously be exchanged prior to the welding operation so that faulty joints are reliably avoided.  
         [0044]    The procedure for producing the electric weld will now be explained in greater detail with reference to FIGS.  2  to  4 . According to FIG.  2 , the three components  1 ,  2  and  3  are inserted into one another in the manner described above. The welding sleeve  3  is provided with holding element  16 , which in this case is segmented. Holding tool  50  comprises two clamp-like jaws  52 ,  53 , between which the holding element  16  can be positioned in the holding tool  50  while components  1 ,  2 ,  3  are inserted, as shown in FIG. 3. The holding tool  50  has at least one additional jaw  54 ,  55 , which is/are spaced at predefined distance(s) from the two aforementioned jaws  52 ,  53 . These distances substantially correspond to the associated outside diameters of components  1 ,  2 ,  3  to ensure a defined orientation relative to the holding tool  50 .  
         [0045]    According to FIG. 4, the two upper jaws  53 ,  55  are moved downward in such a way that the holding element  16  is clamped between the two jaws  52 ,  53  with a defined pressure so as to ensure proper contact with the two contact elements of welding sleeve  3 . As may be seen from FIG. 2, the lower jaw  52  of the holding tool  50  has an additional contact  56  and, correspondingly, the upper jaw  53  has an additional contact  57 . These contacts  56 ,  57  are connected with the welding device via electric lines (not shown). Alternatively, one of the jaws  54 ,  55  (shown on the rear side in the drawing) can be provided with a corresponding contact to establish the electrical connection with an end or a contact of the heating element on an additional holding element that is provided there.  
         [0046]    [0046]FIG. 5 shows a further embodiment similar to FIG. 1, but the pipe with the second component is not shown. The welding sleeve  3  is inserted into the tank opening of tank  8  (only partially shown) by the clamp-like holding tool  50 . Holding tool  50  comprises the two jaws  52 ,  54 , which can be moved relative to one another to grasp and hold the holding element  16 , which is configured as an annular flange. The inner contact  44  or the inner wire end of heating element  4  can be seen on the inner surface of holding element  16 . This inner contact  44  is configured as a circumferentially closed loop with which the additional contact  56  of holding tool  50  engages to establish a reliable contact. The additional contact  56  preferably fits against the inner contact  44  under a predefined tension, which is produced, in particular, by a spring or the like (not shown).  
         [0047]    It should be noted that on the outer surface of the holding element  16 , the wire end is arranged likewise with at least one loop extending over the entire circumference, so that an analogously arranged contact of the lower jaw  52  fits against the outer contact  46  for secure contacting. This annular or circumferentially closed configuration of the inner and the outer contact ensures reliable contacting in every circumferential position of holding tool  50  relative to the welding sleeve  3 .  
         [0048]    According to FIG. 6, pipe  12  with the second component is inserted into the interior of the welding sleeve  3 . It should be noted that the holding tool  50  remains engaged with the contact elements of welding sleeve  3  to maintain electrical contact. By applying the welding energy supplied by a welding device (not shown) to the heating element via the aforementioned contacts, the electric weld of pipe  12  with tank  8  is produced through welding sleeve  3 .  
         [0049]    According to FIG. 7, the holding tool  50  is then disengaged from the welding sleeve  3 . For this purpose, the two jaws  52 ,  54  are moved away from one another so that the holding element  16  is now released and the holding tool  50  can be removed in the direction of arrow  58 .  
         [0050]    In FIG. 8, the holding tool  50  is removed and pipe  12  is now tightly connected with tank  8  by means of welding sleeve  3 . The aforementioned additional contact  57  of the lower jaw  52  of the clamp-like holding tool  50  is clearly visible here.  
         [0051]    [0051]FIG. 9 depicts a longitudinal section of a further embodiment, in which the first component  1  is configured as a sleeve of a second pipe  60 . The first pipe  12  has a constant diameter and the bottom of sleeve  62  of the first component  1  forms a limit stop defining the insertion depth of the first pipe  12 . In other respects, the description provided above applies correspondingly. The two pipes  12 ,  60  are preferably part of a fuel line of a motor vehicle. This fuel line is further connected with a fuel tank as described above.  
         [0052]    [0052]FIG. 10 shows the inventive welding sleeve  3  with outer heating coil  36  and outer contact  46  of the holding element  16 . The inner contact  44  is also clearly visible. Contacts  44  and  46  comprise a plurality of circumferentially closed turns to ensure functionally reliable contacting in any position of the holding tool. The configuration of limit stops  26  as radially outwardly pointing projections is also clearly visible. It should be noted that the heating element  4  configured in this manner advantageously consists of a single continuous wire, which is arranged in the manner shown and described on the inner surface and on the outer surface of the additional component  3 .  
         [0053]    [0053]FIG. 11 shows a special embodiment of the additional component  3 , which is used to position additional devices, e.g., fuel pump, hose holder, sensor, or similar items, in or on a first component, particularly a fuel tank. The additional component  3  is part of a positioning body  64 . The flange-like holding element  16  is also provided. The additional component  3  on one end face  66  carries the heating element  4 , which is configured as a bifilar winding made of an electrically conductive heating wire or resistance wire. The end face  66  has a predefined contour that matches the associated contour of the first component or tank or the like. The surface contour of end face  66  can be flat, as shown, or convex or concave, or configured in some other manner to correspond with the surface contour of the first component on which the positioning body  64  is to be attached and positioned. The one end of the wire is guided to the contact  44  of holding element  16 .  
         [0054]    [0054]FIG. 12 is a side view of component  3  in which the other contact  46  is clearly visible in a constriction below component  3 .  
         [0055]    [0055]FIG. 13 schematically shows the positioning body  64  together with a tank  8  whose outer contour is defined by the installation conditions in a motor vehicle. The tank  8  comprises a tank opening  68  through which the positioning body  64  can be inserted into the interior of the tank and placed at the desired position on the inner tank wall by a tool or handling device  70 , which is not further described here. It should be noted that only after positioning the positioning body  64  on, and producing the welded joint with, the inner tank wall in the manner described above, the tank line or its pipe end is connected with tank  8  in the area of tank opening  68 . The tool or handling device  70  comprises the clamp-like holding tool  50 , which engages with flange  16  and thus securely holds the positioning body  64 .  
         [0056]    [0056]FIG. 14 is an enlarged detail X according to FIG. 13, in which holding tool  50  holds flange  16  between its two jaws  52 ,  54 . The two ends  44 ,  46  of the heating element  4  extend to the holding element or flange  16  where they form the contacts, or are electrically connected with the contacts provided there, particularly by spot welding.  
         [0057]    Alternatively, the contacts or wire ends can be guided to the outer surface  72  of the positioning body  64 , in which case outer surface  72  forms the holding element for the holding tool. In this type of an embodiment, the clamp-like jaws of the holding tool are rotated by 90° compared to FIG. 14 and can be moved in radial direction relative to the positioning body  64  and placed radially onto the outer surface  72  and pressed onto this outer surface with a defined pressure to hold the positioning body  64  and to ensure the required contacting pressure of the additional contact elements.  
         [0058]    According to FIG. 15, tool  70 , which has several knuckle joints  74  to  76 , is partially inserted into the interior of tank  8 . According to FIG. 16, tool  70  is inserted still further into the interior of tank  8 , such that the positioning body  64  is located at the desired position in the interior of the tank. By means of tool  70 , the end face of the additional component of positioning body  64  is pressed against the inner wall of the tank. It should be noted that tool  70  is provided with electric lines that ensure the electric connection between the heating element of positioning body  64  and the welding device. After applying the welding energy required to produce the weld while maintaining a predefined contact pressure by means of the tool or handling device  70 , a secure connection is produced between the positioning body  64  and the inner wall of tank  18 .  
         [0059]    [0059]FIGS. 17 and 18 show a further embodiment in which the additional component  3  is provided with an annular heating element  4  in the form of a bifilar winding on an axial end face  66 . As explained above, the contour of this end face is adapted to the surface contour of the first component to be connected, particularly the inner wall of the fuel tank. A fitting  78 , which is configured as a tank outlet, e.g., for ventilating the tank, is connected with the additional component  3 . The contacts and/or ends  44 ,  46  of heating element  4  lead, as shown, to the outer surface of the flangelike additional component  3 . The holding tool or its clamp-like jaws are pressed against the outer surface  32  in radial direction relative to the longitudinal axis of fitting  78  to hold it and to produce the contact pressure necessary to make the welded joint. Alternatively, a flange-like holding element as described above with reference to FIG. 11 may be provided below, i.e., behind the drawing plane.  
         [0060]    According to FIG. 18, the tank has an opening  80  through which the aforementioned fitting  78  reaches toward the exterior once the additional component  3  has been correspondingly positioned. Prior to that, the additional component  3  was inserted through the first tank opening  68  into the interior of tank  8 , as described above, by means of a tool or handling device (not shown), was positioned underneath the second tank opening  80  and finally moved in the direction of the inner tank wall in such a way that the fitting  78  was reaching through the second tank opening  80  toward the exterior. For the welding operation, the additional component  3  is pressed against the inner wall of tank  8  by the handling device so that the heating element  4  makes contact at a predefined contact pressure and upon delivery of the welding energy a tight and durable joint is produced.  
         [0061]    The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof.