Abstract:
A cable harness is surrounded in certain regions by a sheath made of a casting compound. In order to ensure a defined delimitation of the casting compound, even if there is an insert part protruding from the sheath, the method for sealing a tool opening provides that a pressure element is pressed in the radial direction against the insert part. The insert part is clamped between the pressure element and a support element, and the support element remains in the cable harness as a consumable element. The insert part is particularly designed as a heat protection element. The cable harness is used particularly in a thermally stressed environment for a motor vehicle.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a method for producing a cable harness with an electric wire bundle which is surrounded in certain regions by a sheath made of a casting compound, wherein the wire bundle is placed in a tool mould and the wire bundle is passed through an opening and then is surrounded inside the tool mould by the casting compound. The invention further relates to a cable harness of this kind having an electric wire bundle which is surrounded in certain regions by a sheath of a casting compound. 
     A method of this kind as well as a cable harness of this kind can be concluded by way of example from the DE 19 13 322 C. 
     In order to form the cast or foamed sheaths in the case of cable harnesses a wire bundle is placed in a tool mould and then a casting or foam substance is introduced into the mould so that the sheath is formed. 
     From the DE 37 10 642 A1 a dimensionally stable cable harness is known which has a wire bundle surrounded by a foam sleeve and with defined dimensionally stable branches. 
     The casting or foam substance is normally a very thin fluid in the processing state so that special measures are required to seal off the tool mould at the end in the region of an opening from where the wire bundle exits. From the DE 10 2004 030 026 A1 a slider arrangement is known by way of example for sealing off the opening. From the DE 19 13 322 C can be drawn the use of elastic inserts for sealing off the wire bundle. The wire bundle is thereby surrounded by a banding. 
     Starting from this the object of the invention is to provide a method for producing a cable harness as well as a cable harness wherein the sheath has a defined delimitation in the region of the outlet of the wire bundle. 
     BRIEF SUMMARY OF THE INVENTION 
     As regards the method this is achieved according to the invention as claimed. As regards the cable harness this is achieved according to the invention as claimed. The advantages and preferred configurations outlined below with reference to the method and to the cable harness are to apply equally to both the cable harness and the method. 
     According to this it is proposed that an insert part is placed at least with one end region into the tool mould in order to embed the insert part in the end region in the casting compound. The insert part is guided together with the wire bundle comprising at least one electric wire out from the casting chamber of the tool mould through an opening. For a reliable seal at the outlet point the tool mould has a pressure element which is pressed radially against the insert part. In order to be able to reliably take up the radial pressure force a support element is additionally provided which is placed between the wire bundle and the insert part. The support element therefore defines quasi an abutment for the pressure element so that the insert part is clamped between the pressure element and support element. A defined separating line is thereby provided for the usually very thin liquid casting compound during the casting or injection moulding process. Overall a clear delimitation is thereby achieved in the transition region between the sheath and the insert part emerging from the sheath. The support element is therefore embedded jointly with the insert part at least in part in the casting compound and therefore forms a consumable element which remains in the cable harness. 
     Insofar as the term “casting compound” is used here this is to mean any substance which is introduced in fluid or viscous form into the tool mould and is capable of hardening. More particularly a polyurethane foam system known per se is used as the casting or cast compound which typically has a very low viscosity by way of example in the region of 400 nPa*s. 
     By pressure element is generally meant an element which is suitable for transferring an external pressure force. 
     The cable harness produced according to this method and having an electric wire bundle surrounded in certain regions by a sheath made of a casting compound is therefore also characterized in that the insert part exits together with the wire bundle at the end from the casting compound and forms outside of the casting compound a free outer side of the cable harness and thus for the wire bundle. The support element is arranged between the insert part and the wire bundle in an end region of this free outer side which is thus adjoined by the sheath. The support element is thereby preferably only arranged in this transition region and does not extend over the entire length of the insert part. The support element is thereby preferably a dimensionally stable inherently rigid element, more particularly a sleeve, which surrounds the wire bundle in the manner of a ring. Since the casting compound surrounds the wire bundle and at the same time the insert part is arranged radially on the outside, the insert part is spaced from the wire bundle so that a free radial space, more particularly an annular space is formed between the wire bundle and the insert part. 
     By free outer side is generally meant here that the insert part delimits the wire bundle radially on the outside, preferably without arranging a further sheath or casing around the insert part. 
     The insert part is thereby preferably designed as a heat protection element for the wire bundle. 
     The cable harness preferably serves as a whole for use in a motor vehicle, more particularly in the engine chamber, and is arranged at least close to the component parts which become hot during use. The wire bundle is therefore protected from the heat by means of the insert part which is thus embedded by an end region in the sheath but otherwise defining outside of the sheath a protection element for the wire bundle. A complete embedding of the wire bundle in a high-temperature-resistant plastics is therefore not necessary. This thereby reduces the material costs and also reduces the space required. For an efficient heat protection function the insert part is formed from a temperature-stable material, by way of example from a temperature-stable plastics or also more particularly from metal. More expediently it has a metallized or even metallic and more particularly a reflective surface. 
     In the case of the method, in order to achieve a secure seal an external pressure force is exerted on the pressure element and is transferred to the support element. The pressure element is for this purpose formed in a preferred configuration as a separate dimensionally-stable component part on the tool mould in the region of the opening through which the wire bundle and the insert part exit together. The component part itself can also define at least in part the opening. The component part is thereby preferably arranged displaceable in the radial direction relative to a wall of the tool mould. The casting chamber is restricted in the longitudinal direction of the cable through wall regions of the tool mould. Therefore only the opening is closed at the end by the pressure element. As a result of the separate configuration the pressure element can be formed suitable for transferring high compressive forces. The pressure element itself is thereby mounted either at or also in a recess of the wall of the tool mould. 
     In a particularly advantageous configuration the insert part extends in the longitudinal direction of the cable between two end regions wherein one pressure element is pressed against the insert part in each end region. Only the end regions are thereby each embedded in a respective sheath so that preferably a sheath of casting compound adjoins the insert part at both ends. The insert part is not enclosed by the casting compound between these two end regions. 
     The insert part is thereby expediently inserted into one common tool mould comprising the two pressure elements which has two casting chambers spaced from one another in the longitudinal direction of the cable and between which the insert part extends. The insert part is therefore embedded and held at both ends in the respective sheaths. The insert part extends over the entire free length between the sheaths and protects the wire bundle in this region which is not encased by the casting compound. 
     According to a first design variation the insert part surrounds the wiring as a whole in the manner of a tube so that this is protected on all sides. The insert part itself is thereby formed by way of example as a tube through which the wire bundle is guided. Alternatively the possibility also exists of designing the insert part in the manner of a mesh or winding or even of a combination of a tube and a winding. More expediently the insert part is thereby formed by a foil or has at least at one foil. In a particularly preferred configuration the insert part is formed as a hybrid component part of several layers and preferably has an inner tube, by way of example a woven tube which is enclosed, more particularly wound, by a heat-resistant foil, more particularly a metal foil. 
     Alternatively to this tubular formation of the insert part the latter does not extend over the complete perimeter of the wire bundle but only over a restricted angular region. The pressure element preferably extends identically over the same angular region as the insert part. In order to achieve a reliable seal it is hereby preferably proposed that the insert part is clamped in a separation plane of the tool mould. For this it is proposed by way of example that the insert part has in the region of the separation plane radially protruding edge regions which are clamped. 
     Generally in an expedient design the pressure element is provided with a sealing lip. The sealing lip is preferably formed as a rib-like element which runs circumferentially along a sealing line. The surface pressure force is hereby increased for a good seal. Expediently the sealing lip is therefore formed as a substantially rigid element. Alternatively to this the possibility exists that the sealing lip is formed as an elastic element, by way of example as a rubber seal. 
     Expediently the pressure element is assigned an opposing abutment wherein the insert part is clamped between the pressure element and the abutment. The pressure element and the abutment therefore preferably make up a clamping or pressure ring which surrounds the wire bundle and the insert part in a ring. Its cross-sectional contour is therefore adapted to that of the insert part. The abutment is thereby like the pressure element formed as an independent preferably dimensionally-stable component and is by way of example likewise like the pressure element provided with a sealing lip. 
     Alternatively to this separate configuration the abutment is a partial region of a wall of the tool mould itself. The pressure element as well as the abutment are preferably each formed as a half shell. 
     It is furthermore preferably provided that the pressure element has edge regions with which it bears on the abutment. The abutment itself is preferably formed approximately U-shaped and the insert part fits with a tight fit therein. The pressure element engages in the opening open at the top of the U-shaped recess and preferably has an end section which extends out in wedge fashion and which is clamped between the abutment and the insert part. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Embodiments of the invention will now be explained in further detail with reference to the figures. These show each in simplified illustrations: 
         FIG. 1  a longitudinal sectional view through a tool mould having the wire bundle as well as the insert part inserted therein; 
         FIG. 2  a cross-sectional view through the tool mould according to  FIG. 1  along the line II,II; 
         FIG. 3  a longitudinal sectional view through a cable harness; 
         FIG. 4  a cross-sectional view through the cable harness according to the sectional line IV-IV in  FIG. 3 ; 
         FIG. 5  a cross-sectional view of the cable harness according to the sectional line V-V in  FIG. 3 ; 
         FIG. 6  a cross-sectional view of the cable harness along the sectional line VI-VI in  FIG. 3 ; as well as 
         FIG. 7  a cross-sectional view comparable with  FIG. 2  of the tool mould with an alternative configuration of the insert part. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     In the drawings the similar acting parts are provided with the same reference numerals. 
     The tool mould  4  illustrated in  FIG. 1  is used for producing the cable harness  2  illustrated in  FIG. 3 . The tool mould  4  as well as the cable harness  2  each extend in the longitudinal direction  6  of the cable. The tool mould  4  thereby normally has two tool parts formed in the manner of half shells which are divided along a tool separation plane  8  extending in the cable longitudinal direction  6 . A wall  10  of the tool mould defines a free interior space  12  in which a wire bundle  14  as well as an insert part  16  formed as a heat protection element are inserted. The wire bundle  14  is normally wound up additionally by a banding which is not shown in further detail here. 
     The insert part  16  thereby extends in the cable longitudinal direction  6  between two end regions  18 . In each end region  18  there is a support element designed as a support ring  20  which on the one side surrounds the wire bundle  14  and on the other side is covered by the inverted respective region  18   b  of the insert part  16 . The insert part  16  thereby protrudes in part in the cable longitudinal direction  6  over each support ring  20 . 
     A free space is formed between the wire bundle  14  and the support ring  20  so that the wire bundle  14  is guided loosely through the insert part. The distance between the wire bundle  14  and the insert part  16  thereby corresponds roughly to the sleeve thickness of the casting compound  28  surrounding the wire bundle  14 . 
     The tool mould  4  furthermore has two clamping rings  22  spaced from one another in the cable longitudinal direction  6  and formed from a pressure element  22   a  and an abutment  22   b  for this. The clamping rings  22  each define an opening  23  through which the wire bundle  14  is guided. The pressure element  22   a  as well as the abutment  22   b  are thereby mounted movable in the radial direction inside the wall region  10  of the tool mould  4 , at least the pressure element  22   a , so that a radial pressure force exerted on the pressure element  22   a  is transferred via the pressure element  22   a  to the insert part  16 . 
     As can be seen from  FIG. 1  the support ring  20  is arranged in the region of the respective pressure element  22   a  so that the insert part  16  is clamped between each pressure element  22   a  or the abutment  22   b  respectively, and the support ring  20 . 
     In order to improve the sealing action and increase the surface pressure force applied, both the pressure element  22   a  and the abutment  22   b  have a sealing lip which is moulded as a clamping or sealing rib  24  and which as a whole runs completely round the entire surface of the insert part  16 . 
     The tool mould is divided at the openings  23  by the two clamping rings  22  into several partial areas, three in the design variation of  FIG. 1 , namely into two outer regions and one central region. The insert part  16  runs in the central region, and extends into the outer regions only partially by the end regions  18 . These two outer regions of the free interior space  12  thereby each define a casting chamber  26  which is filled with a casting compound  28  (see  FIG. 3 ). 
     Complementary with the variation illustrated in  FIG. 1  the individual wires of the wire bundle  14  are preferably still guided through a separator (not shown here in further detail) so that the central region is sealed from the two casting chambers  26  also in the central area surrounded by the insert part  16 . 
     To produce the cable harness  2  the wire bundle  14  is inserted together with the support rings  20  and the insert part  16  into the tool mould  4 . If—as by way of example with the embodiment according to  FIGS. 2 to 6 —there is a tubular insert part  16  as well as an annular support element  20  then the wire bundle  14  is guided through the respective support ring  16  and then the tubular insert part  16  is pushed over the wire bundle  14  and over the support rings  20 . The support rings  20  are positioned in the tool mould  4  in the region of the clamping rings  22 . The two tool halves are then closed. A contact pressure force applied externally is then exerted via the pressure element  22   a  which is designed in particular in the manner of a cable pressure strip, so that the insert part  16  is clamped between the pressure element  22   a  and the support ring  20 . The casting compound  28  is then introduced into the casting chambers  26  through injection casting openings which are not shown in further detail here. The casting compound  28  is in particular a polyurethane foam system which typically has a very high initial viscosity. 
     The entire cavity in the casting chamber  26  is then filled by the expanding casting compound  28 . The partial region of the end regions  18  extending into the casting chamber  26  is then embedded in the casting compound  28 . As a result of the high viscosity the casting compound  28  is also placed circumferentially around the insert part  16 . The casting compound  28  therefore projects between the inside of the pressure element  22   a  or the abutment  22   b  and the insert part  16 . The sealing rib  24  restricts the expansion in the cable longitudinal direction  6 . Through this measure it is therefore reliably ensured that a defined clear separation point is formed and the casting compound  28  does not project into the central region. The outside of the insert part  16  in this central region therefore forms a free outer side  30  which is not encased by the casting compound  28 . A sheath  32  formed by the casting compound  28  therefore adjoins this free outer side  30 . This sheath has in the embodiment a rectangular cross-sectional contour. 
     In order to achieve a reliable seal in the boundary area between the sheath  32  and the free outer side  30 , in the embodiment of  FIG. 2  the abutment  22   b  has a roughly U-shaped opening in which the insert part  16  is placed together with the support ring  20  and the wire bundle  40 . The pressure element  22   a  is placed on the abutment  22   b  in the manner of a T-shaped pressure strip. Both the pressure element  22   a  and the abutment  22   b  are each designed with a concave curvature on the inside corresponding to the contour of the support ring  20 . Two end portions  34  extending out in wedge fashion are thereby produced in the connection with the U-shaped receiving area on the sides of the pressure element  22   a.    
     As an alternative to this the pressure element  22   a  and abutment  22   b  are formed by two similar shaped half-shell elements. The separation plane between the pressure element  22   a ,  22   b  preferably corresponds to the tool separation plane  8 . 
     As can be further seen from the cable harness illustrated in  FIG. 3 , branches  36  are formed in the two opposing sheaths  32  so that a partial bundle  38  of the wire bundle  14  is branched off from the cable longitudinal direction  6 . The partial bundle  38  is thereby likewise surrounded by the sheath  32  so that the branch  36  is held overall dimensionally stable and the exit angle of the partial bundle  38  is fixedly defined. Furthermore it can be seen that the wire bundle  14  again exits from the sheaths  32 . The sheaths  32  are therefore formed only in the region of the branch  36 . The wire bundle  14  as well as the partial bundle  18  are then guided further on to the electrical components to which they are connected. For insertion into a respective housing of the electrical components sealing pockets are thereby formed for example on the respective wire bundle  14  or partial bundle  18 , and are preferably likewise formed as a cast part. 
     From  FIGS. 4 to 6  can be seen again the individual cross-sectional geometries in the various different regions, namely in the region of the support ring  20  surrounded by the sheath  32  ( FIG. 4 ), in the free end region  18  directly adjoining the sheath  32  ( FIG. 5 ), as well as in the central region between the two sheaths  32  ( FIG. 6 ). As a result of the special manufacturing method the support ring  20  which is embedded in the sheath  32  and extends out therefrom, is arranged in the end region  18 . 
     With the design variation illustrated in  FIGS. 3 to 6  the insert part  16  is formed tubular and therefore surrounds the wire bundle  14  around the entire periphery. The free outer side  30  which protects the wire bundle  14  more particularly against the effects of heat, thereby preferably extends over several tens of centimeters. The cable harness  2  is arranged in the fully assembled state preferably in a motor vehicle and more particularly there in a heat-stressed partial area, by way of example in the engine chamber and/or in the region of the exhaust train. 
     The insert part  16  is thereby designed more particularly as a flexible tube, preferably in the manner of a hybrid tube with an inner woven or mesh tube which is wrapped round by a metal banding. With this design the cable harness  2  is formed very elastic and bending in the region of the free outer side  30  and can then be laid without problem even if bent. 
     As an alternative to the tubular design of the insert part  16 , according to the design variation illustrated in  FIG. 7 , the insert part extends only over a partial region and is by way of example formed in the manner of a solid, inherently rigid, by way of example metal, profile, as illustrated in  FIG. 7 . More expediently with an insert part  16  of this kind extending only over a restricted angular region, an annular support element  20  is used in order to be able to readily absorb the clamping forces. As an alternative to this the support element  20  is adapted to the contour of the insert part  16 . As shown in  FIG. 7 , the insert part  16  in this embodiment has outwardly protruding marginal regions  40  which are clamped between the pressure element  22   a  and the abutment  22   b . These marginal regions  40  thereby preferably lie inside the tool separation plane  8 . 
     LIST OF REFERENCE NUMERALS 
     
         
           2  Cable harness 
           4  Tool mould 
           6  Cable longitudinal direction 
           8  Tool separation plane 
           10  Wall 
           12  Interior space 
           14  Wire bundle 
           15  Banding 
           16  Insert part 
           18  End region 
           20  Support ring 
           22  Clamping ring 
           22   a  Pressure element 
           22   b  Abutment 
           23  Opening 
           24  Sealing rib 
           26  Casting chamber 
           28  Casting compound 
           30  Free outer side 
           32  Sheath 
           34  End portion 
           36  Branch 
           38  Partial bundle 
           40  Marginal region