Patent Publication Number: US-2022212511-A1

Title: Multi-Point Link for an Undercarriage of a Vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. national stage of International application No. PCT/EP2020/060017, filed on Apr. 8, 2020, which claims priority to German Application No. 10 2019 206 435.3, filed May 6, 2019, the content of each of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to a multipoint link for an undercarriage of a vehicle. The present invention is further directed to a method for producing a multipoint link for an undercarriage of a vehicle. 
     2. Description of the Prior Art 
     Multipoint links, for example, a four-point link, are used particularly in utility vehicles to guide a rigid axle resiliently in a vehicle frame. A multipoint link constructed as a four-point link takes on the functions of transverse guidance and longitudinal guidance of the rigid axle. Beyond this, a multipoint link of this kind performs the function of a stabilizer and is therefore is exposed to additional roll loads, during roll motions of a vehicle body which occur, e.g., during cornering. 
     A multipoint link constructed as a three-point link is used in tractor units in the utility vehicle sector to link the axle to the structural frame. Three-point links contribute in large measure to the transverse guidance and longitudinal guidance of the axle. A three-point link guides the axle in an upper link plane and is exposed to high longitudinal loads and transverse loads during driving operation of the utility vehicle. 
     A multipoint link of the type mentioned above is known from DE 10 2016 209 041 A1. The multipoint link comprises a core element made from a foamed material and at least one roving (filament bundle) which is wound around the core element. The at least one roving winding around the core element in at least one layer forms an outer layer of the multipoint link. The core element is provided mainly to form the inner shape of the multipoint link. The core element itself is not provided for absorbing loads or, if so, only conditionally. Rather, it is provided primarily for laying or wrapping with the roving in order to form a loadable supporting structure. Loads and forces which are introduced into the multipoint link in load introduction areas provided for this purpose through a vehicle axle or a wheel carrier are chiefly absorbed by the outer layer of the multipoint link formed from at least one roving. The core element around which the at least one roving is wound during a winding process provides the respective component contour of the multipoint link. The core element must absorb the forces exerted on it during the winding process, particularly at the start of the winding process, by the at least one roving which is kept under tension. The core element may deform only very slightly during winding because the core element imparts shape to the multipoint link, and substantial geometric dimensions (kinematic points) of the multipoint link must be set within close tolerances. To this end, the core element known from DE 10 2016 209 041 A1 is constructed as a permanent and simultaneously solid core. Constructing as a solid core is disadvantageous in that it has a relatively high mass because of the high-density foamed material which is utilized. The construction of the core element as a temporary core element in the form of a disposable core has the disadvantage of a high expenditure for producing a disposable core of this kind and for its removal from the finished multipoint link. 
     A multipoint link is also known from U.S. Pat. No. 4,650,629. 
     SUMMARY OF THE INVENTION 
     Proceeding from the prior art described above, it is an object of the present invention to further develop a multipoint link for an undercarriage of a vehicle, particularly passenger car or utility vehicle, which in particular enhances its suitability for high-volume production and accelerates the production process while lowering costs. 
     This object may be met with respect to an apparatus in which a multipoint link for an undercarriage of a vehicle comprises a core element formed from a foamed material and at least one roving of bundled continuous filaments wound around the core element. The at least one roving winding around the core element in at least one layer forms an outer layer of the multipoint link. The core element is constructed as a hollow body that comprises at least two shell elements. The construction of the core element as a hollow body that includes at least two parts has the advantage of a smaller mass compared to a solid core. The at least two shell elements can be produced more simply and inexpensively than core elements constructed as solid cores or disposable cores with reduced material input. Compared with disposable cores, the core element constructed as multiple-part hollow body has the additional advantage that loads can be absorbed during the use phase of the multipoint link in that the layer formed by winding remains in the interior. In addition, the foamed material can preferably have a higher density than foamed material which may be used to produce solid cores. 
     In particular, the roving can be impregnated immediately before winding around the core element, or a roving which is preimpregnated with resin (towpreg semifinished product) can be used. In the wet winding process, the roving is impregnated with resin immediately before winding and is wound around the core element. A maximum layup speed of the roving on the core element is limited to approximately 0.5 m/s due to the resin losses caused, for example, by centrifugal forces during the winding. By comparison, the layup speed can be substantially increased through the use of preimpregnated rovings because the resin is cured and centrifugal forces therefore have no influence. Robot-based 3D filament winding processes in particular allow a selective filament-optimized placement of preimpregnated rovings at a very high layup speed on a core element with virtually any desired contour. A towpreg semifinished product is preferably used to achieve the highest winding speeds. Owing to the tackiness of the preimpregnated semifinished product and the multi-axial rotation of component and rovings by one or more robots or rotary frames, curved winding paths can also be generated outside of a geodesic path, that is, outside of a shortest path connecting two points. 
     By roving is meant a bundle, strand or multifilament yarn comprising filaments (continuous fibers) arranged in parallel which is used predominantly for manufacturing fiber-reinforced plastics. Most often, filaments of glass, aramid or carbon are combined to form rovings. 
     The at least two shell elements are connected to one another by positive engagement and material bonding. The at least two shell elements can preferably be connected to one another by positive engagement and/or frictional engagement and/or material bonding. In the simplest case, the at least two shell elements can be connected to one another by material bonding by gluing. Gluing has the advantage that the hollow body forming the core element can be constructed fluid-tight. A positive engagement connection of the at least two shell elements offers the advantage that the positioning of the at least two shell elements when joined to form the core element can be predetermined. 
     In particular, the core element can have portions arranged at distal ends for receiving load introduction elements. To this end, bushings serving to introduce loads can be arranged in the portions of the core element, these bushings serving to receive load introduction elements. The load introduction elements can be constructed as ball-and-socket joints or elastomer bearings or molecular bearings, the bearing components being at least partially received by the bushings. 
     According to a preferred further development, the at least two shell elements can be formed symmetrical. In particular, when the core element to be produced has two perpendicular symmetry axes, the at least two shell elements can be produced by only one die. 
     The at least two shell elements can preferably have an internal supporting structure. The core element can be stiffened by the internal supporting structure. By providing the internal supporting structure, the core element can be constructed with thinner walls so that a further reduction in mass can be achieved. The internal supporting structure can be formed, for example, by point-shaped or line-shaped spacer elements or ribs. The spacer elements or ribs preferably extend substantially perpendicular to the inner surface of the respective shell element. Accordingly, the spacer elements or ribs can be arranged opposite one another in the joined position of the shell elements forming the core element. 
     It is advantageous when the at least two shell elements are connected by positive engagement and/or frictional engagement by the supporting structure. To this end, the supporting structure can be constructed as complementary connection elements which engage in one another at least in positive engagement when the at least two shell elements are joined together. Additionally, the complementary connection elements can be constructed with undercuts. The undercuts can be formed in a mushroom-shaped manner or as a stop. In this way, a kind of snap-in connection can be realized between the at least two shell elements. The production of the shell elements with undercuts is made possible when the foamed material used for production permits a nondestructive forced demolding from the die. 
     According to a preferred further development, the internal supporting structure can be formed as a material accumulation extending in portions over a two-dimensional plane of the respective shell element. The position and arrangement of the material accumulation can be provided, for example, at least partially by winding paths of the at least one roving. An at least partial orientation of the run of the material accumulation to load paths along which loads can be absorbed and transferred by the multipoint link is likewise advantageous. It will be appreciated that a material accumulation can be provided in combination with a supporting structure comprising point-shaped or line-shaped spacer elements or ribs. 
     In particular, the material accumulation can form a framework-like structure. A high load carrying capacity and stiffness of the shell elements can be achieved in this way. 
     Further, in order to join the at least two mated shell elements to form the core element, at least one separate roving can be provided to wind in portions around the at least two mated shell elements. By winding at least one separate roving around the at least two mated shell elements, joining is achieved by binding. Accordingly, a connection of the at least two shell elements through material bond, frictional engagement or positive engagement can be entirely or at least partially dispensed with. 
     In order to strengthen the core element, separate rovings can preferably be arranged in the interior and/or exterior of the core element in guide channels. A further strengthening of the core element can be achieved by arranging separate rovings in guide channels on the inner side of the shell elements and/or on the outer side of the shell elements, i.e., in the interior or on the exterior of the core element. The separate rovings can be arranged in an automated manner by robots. The laying of the separate rovings in the incorporated guide channels can be carried out such that a framework-like structure is formed. This makes the core element dimensionally stable, and the core element can absorb higher loads during the subsequent winding process. It is particularly advantageous when the framework-like structure on the outer side of the core element can be connected to the at least one roving forming an outer layer of the multipoint link by the winding process. A strengthening of the supporting structure of the core element can be achieved in this way. The separate rovings in the core element and on the outer side thereof function as framework-like inlay and stiffening of the supporting structure. Since the separate rovings need not be laid on free geodesic paths but rather are located in the guide channels, a very free and selective strengthening of the structure is possible, for example, for particularly load cases. 
     The shell elements which are brought together to form the core element are formed with walls which are substantially perpendicular to one another and which delimit the outer contour. The walls have undercuts which engage in one another by positive engagement in the joined state of the shell elements. Further, the walls have complementary undercuts at joining surfaces facing one another such that the at least two shell elements engage in one another in portions when put together. In addition, an adhesive can be applied in this area in order to connect the at least two shell elements by positive engagement as well as by material bonding. In particular, the undercuts are formed as projections, for example, in the form of steps. 
     The at least two shell elements can preferably be constructed fluid-tight in joined position so that a hollow space enclosed by the at least two shell elements can be filled with a fluid. The fluid-tight construction of the core element can be achieved in particular by a material bond connection of the shell elements, for example, by gluing. The temporary load carrying capacity which is required particularly at the start of the winding of the at least one roving can be increased in this way. The core element is additionally stabilized in that the hollow space in the core element is temporarily pressurized during winding through an internal pressure by a fluid, a liquid or a gas. 
     A functional element can preferably be inserted into the core element formed as hollow body before the winding. It is conceivable, for example, to arrange electronics components, for example, a printed circuit board, an energy accumulator, a data storage, a radial module and the like before joining and before subsequent winding around the core element. Functional elements of this type can be used, for example, for a system for damage detection or for detecting load cycles of the multipoint link. The advantage of the multiple-part core element consists in that the functional elements can be installed in a simple manner before assembling the core. 
     The above-stated object is further met by a method for producing a multipoint link. 
     According to this, a method for producing a multipoint link for an undercarriage of a vehicle is suggested. The method is characterized by the following method steps: producing at least two shell elements from a foamed material; joining the at least two shell elements to form a hollow core element; and winding around the core element with at least one roving of bundled continuous filaments. 
     The construction of the core element as a hollow body comprising at least two parts has the advantage of a smaller mass compared to a solid core. The at least two shell elements can be produced more simply and inexpensively than core elements constructed as solid cores or disposable cores with reduced material input. Compared with disposable cores, the core element constructed as a multiple-part hollow body has the additional advantage that loads can be absorbed during the use phase of the multipoint link. In addition, the foamed material can preferably have a higher density than foamed material which may be used to produce solid cores. 
    
    
     
       BRIEF DESCRIPTION FO THE DRAWINGS 
       Advantageous embodiment forms of the invention which will be described in the following are shown in the drawings. The drawings show: 
         FIGS. 1A to 1C  schematic views of multipoint links for an undercarriage of a vehicle; 
         FIG. 2  a schematic top view of a multipoint link constructed as four-point link; 
         FIG. 3  a schematic perspective partial view of a core element of the multipoint link according to  FIG. 2 ; 
         FIG. 4  a schematic view of the core element according to  FIG. 3  with a shell element shown transparently; 
         FIG. 5  a schematic sectional view of the core element along line A-A according to  FIG. 3 ; 
         FIG. 6  a detail X according to  FIG. 5 ; 
         FIG. 7  a schematic view of a further embodiment form of the core element according to  FIG. 3  with a shell element shown transparently; 
         FIG. 8  a schematic perspective partial view of a core element with an external supporting structure; 
         FIG. 9  a schematic view of a guide channel for laying a supporting structure formed as at least one separate roving on the outer side of the core element; and 
         FIG. 10  a schematic view of a guide channel according to a further embodiment form. 
     
    
    
     DETAILED DESCRIPTION FO THE PRESENTLY PREFERRED EMBODIMENTS 
     In the following, identical reference numerals are used for identical or functionally similar components. 
       FIGS. 1A to 1C  show schematic views of different multipoint links  1  for an undercarriage—not shown—of a vehicle.  FIG. 1A  shows a multipoint link  1  constructed as a three-point link. The multipoint link  1  comprises a body  2  having a plurality of force introduction areas  4  which are connected to one another by a connection structure  3 . The body  2  substantially determines the basic shape of the multipoint link  1 . A multipoint link  1  constructed, for example, as a four-point link or as a five-point link is shown in  FIGS. 1B and 1C . Multipoint links  1  can connect kinematic points in an undercarriage and/or in a wheel suspension and transmit movements and/or forces. The connection of the multipoint link  1  to further component parts of the undercarriage can be realized by joints which are arranged in the force introduction areas  4 . 
       FIG. 2  schematically shows a top view of a multipoint link  1  constructed as four-point link. The multipoint link  1  according to the invention comprises a core element  5  which is formed from a foamed material and at least one roving  10  of bundled continuous filaments wound around the core element  5 . The at least one roving  10  wound around the core element  5  in at least one layer forms an outer layer of the multipoint link  1 . The core element  5  has a torsion element  6  and four supporting arms  7  which are connected integral with the torsion element  6 . Portions  8  for receiving load introduction elements are arranged at the distal ends of the supporting arms  7 . To this end, a bushing  9  for receiving a respective load introduction element—not shown—constructed as a ball-and-socket joint or elastomer bearing is arranged at the respective portion  8 . The multipoint link  1  constructed as four-point link is used, for example, in a utility vehicle as an undercarriage link and combines the functions of a separate three-point link and a separate roll stabilizer in a single undercarriage component. Accordingly, the multipoint link  1  constructed as four-point link takes on the task of transverse guidance and longitudinal guidance of a rigid axle as well as roll stabilization. 
       FIG. 3  schematically shows a perspective partial view of only the core element  5  according to  FIG. 2 . According to the invention, the core element  5  is constructed as a hollow body which comprises at least two shell elements  11 ,  12 , which are joined together. In the depicted embodiment example, the lower shell element  11  and the upper shell element  12  are formed as half-shells. The at least two shell elements  11 ,  12  are preferably symmetrically constructed. The shell elements  11 ,  12  constructed as half-shells have a substantially U-shaped profile cross section. The shell elements  11 ,  12  which are joined together to form the core element  5 , have walls  13 ,  14  which are substantially perpendicular to one another. The walls  13 ,  14  delimit the outer contour of the respective shell elements  11 ,  12 . End faces at the walls  13 ,  14  form abutment surfaces  15 ,  16  which extend transverse to walls  13 ,  14  and on which the shell elements  11 ,  12  sit one upon the other after being joined. An adhesive can be applied to one or both abutment surfaces  15 ,  16  prior to joining for a nondetachable connection so that a material bond of the at least two shell elements  11 ,  12  is achieved. The material bond connection also makes it possible to construct the core element  5  to be fluid-tight. 
       FIG. 4  schematically shows the core element  5  according to  FIG. 3  with an upper shell element  12  shown transparently. Connection elements  17 ,  18  which are arranged opposite one another in the interior of the two shell elements  11 ,  12  and are constructed in particular to complement one another are visible through the transparent depiction of the upper shell element  12 . The connection elements  17  of the lower shell element  11  can be constructed as cylindrical pins, and the connection elements  18  of the upper shell element  12  can be constructed as hollow-cylindrical portions in which the connection elements  17  constructed as cylindrical pins can be inserted. The at least two shell elements  11 ,  12  are connected with one another by positive engagement and/or frictional engagement by the complementary connection elements  17 ,  18 . Further, the at least two shell elements  11 ,  12  can be fixed with respect to their position by the connection elements  17 ,  18  when joined. 
     Further, the connection elements  17 ,  18  function as a supporting structure  19  in the interior of the core element  5 . Accordingly, the core element  5  is stiffened, which increases the loadability of the core element  5  particularly at the start of the winding process. 
     Alternatively, the supporting structure  19  in the interior of the respective shell element  11 ,  12  can be constructed as ribs or as point-shaped and/or line-shaped spacer elements. In the joined state of the shell elements  11 ,  12 , the ribs or point-shaped and/or line-shaped spacer elements sit one on top of the other so that the compressive forces which are absorbed when the at least one roving  10  is wound around the core element  5  and which result from the filament tension of the roving  10  do not lead to an unwanted deformation of the core element  5 . 
       FIG. 5  schematically shows a sectional view of the core element  5  along line A-A according to  FIG. 3 . The section through two of the connection elements  17 ,  18  illustrates the positive engagement connection between the two shell elements  11 ,  12  by the connection elements  17 ,  18 . In general, two dies are required for producing the at least two shell elements  11 ,  12  in order to form the shell elements  11 ,  12  with the complementary connection elements  17 ,  18 . However, it is also possible to use only one die if the core element  5  to be produced has at least two perpendicular symmetry axes and the symmetrical conditions are utilized in a corresponding manner. 
       FIG. 6  shows a detail X according to  FIG. 5 . The walls  13 ,  14  of the shell elements  11 ,  12  have undercuts  29 , respectively, which engage in one another by positive engagement when the shell elements  11 ,  12  are joined. In this way, the two shell elements  11 ,  12  are secured at least against displacement in transverse direction of the core element  5 . The undercuts  29  are formed in this instance as projections in the form of steps. 
     A further embodiment form of the core element  5  according to  FIG. 3  is shown schematically in  FIG. 7  with an upper shell element  12  shown transparently. This embodiment form has, in addition, a supporting structure  19  which is formed as a material accumulation  20 , particularly a structured material accumulation  20 , extending in portions over an internal two-dimensional plane of the respective shell element  11 ,  12 . The shape of the material accumulation  20  on the respective inner side of the shell elements  11 ,  12  can preferably correspond to a framework-like structure. 
       FIG. 8  schematically shows a perspective partial view of a core element  5  with an external supporting structure  21 . The external supporting structure  21  comprises at least one separate roving  22 ,  23 ,  24 ,  25 . A plurality of separate rovings  22 ,  23 ,  24 ,  25  are preferably provided in order to join and connect the at least two shell elements  11 ,  12  to one another to form the core element  5 . Therefore, undercuts at the abutment surfaces  15 ,  16  or gluing the at least two shell elements  11 ,  12  to one another can be dispensed with. Further, an additional stabilization of the core element  5  is achieved by the separate rovings  22 ,  23 ,  24 ,  25  so that this core element  5  can absorb higher loads during the subsequent winding process. 
     It is provided to arrange guide channels  26  in the surface on the outer side of the at least two shell elements  11 ,  12  as is shown schematically in  FIG. 9 . These guide channels  26  can be incorporated in the shell elements  11 ,  12  already during the production process for the latter. Alternatively, the guide channels  26  can be incorporated by a subsequent machining of the surface of the shell elements  11 ,  12  or of the core element  5  after it has already been assembled. 
     The arrangement of the guide channels  26  is preferably carried out independent from geodesic paths. Accordingly, the separate rovings  22 ,  23 ,  24 ,  25  can be freely laid on the surface of the shell elements  11 ,  12  in order to selectively generate a shape of the supporting structure  21  which at least partially enables a laying of the separate rovings  22 ,  23 ,  24 ,  25  independent from the external shape of the core element  5 . In this respect, the shapes of the separate rovings  24  and  25  are referred to by way of example. The laying of the rovings  24  and  25  serves to fix and tighten roving  22  in the guide channel  26  provided therefor, this roving  22  surrounding the core element  5  in circumferential direction along the narrow perpendicularly extending wall  14 . The separate rovings  22 ,  23 ,  24 ,  25  can likewise be produced by a robot and preferably form a framework-like structure. 
     In a further aspect, the separate rovings  22 ,  23 ,  24 ,  25  by which the at least two shell elements  11 ,  12  are bound and joined are connected to the roving  10  wound around the core element  5  to form an outer layer. Accordingly, a strengthening of the supporting structure of the core element  5  is achieved. In so doing, the separate rovings  22 ,  23 ,  24 ,  25  on the surface of the core element function as framework-like inlay and stiffening of the supporting structure. Since the separate rovings  22 ,  23 ,  24 ,  25  need not be laid on free geodesic paths but rather are located in the guide channels  26 , a very free and selective strengthening of the structure is possible, for example, for determined load cases. 
       FIG. 9  shows a schematic view of a guide channel  26  for laying a supporting structure  21  formed of at least one separate roving  23  on the outer side of the core element  5  and the guide channel  26  with a roving  23  laid therein. The guide channel  26  is constructed as a recess with an arcuate cross section in which the separate roving  23  is laid. According to a further development shown in  FIG. 10 , the guide channel  26  can have undercuts  28  at the wall portions  27  delimiting the guide channel  26  in order to improve the guiding and holding of the separate rovings  22 ,  23 ,  24 ,  25  in the respective guide channel  26 . Accordingly, a better lateral fixing of the separate rovings  22 ,  23 ,  24 ,  25  laid in the guide channels  26  is achieved in particular. 
     Although exemplary embodiments have been discussed in the above description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples which are not intended to limit the scope of protection, the applications and the structure in any way. Rather, a person skilled in the art will take from the above description a guideline for implementation of at least one exemplary embodiment, wherein various modifications may be made, in particular with regard to the function and arrangement of the described components, without departing from the scope of protection as can be gathered from the claims and equivalent feature combinations. 
     REFERENCE NUMERALS 
       1  multipoint link 
       2  body 
       3  connection structure 
       4  force introduction area 
       5  core element 
       6  torsion element 
       7  supporting arm 
       8  portion 
       9  bushing 
       10  roving 
       11  shell element 
       12  shell element 
       13  wall 
       14  wall 
       15  abutment surface 
       16  abutment surface 
       17  connection element 
       18  connection element 
       19  supporting structure 
       20  material accumulation 
       21  supporting structure 
       22  roving 
       23  roving 
       24  roving 
       25  roving 
       26  guide channel 
       27  wall portion 
       28  undercut 
       29  undercut