Abstract:
A force connection strut ( 1 ) of a chassis of a passenger car or utility vehicle is provided for the non-positive connection between a chassis and a wheel carrier, preferably an axle strut or a chassis control arm. An elongated basic body (G) and at least two end-side mount supports ( 5 ) are provided for introducing and leading out forces.

Description:
FIELD OF THE INVENTION 
   The present invention pertains to a force connection strut of a chassis of a motor vehicle with an elongated basic body and at least two end-side mount supports for introducing and leading out forces. 
   BACKGROUND OF THE INVENTION 
   Such chassis parts are generally known and can be used as a connection between the chassis and the wheel carrier or as an axle strut or chassis control arm. Reference is made as an example to the documents DE 41 20 772 C2, DE 33 32 771 C2 and DE 199 31 079 A1. 
   The above-mentioned documents pertain to force-transmitting chassis parts, which comprise essentially an elongated basic body and end-side mount supports with mounts. Even though the mount supports and mounts are made in these cases of composite materials, i.e., a combination of metals and plastic portions, the elongated basic body nevertheless always consists of metal. 
   It was found in the course of the development that the chassis parts, whose basic body is made mostly of forged steel or gray cast iron, do not sufficiently meet the increased requirements any longer in terms of their material properties, and the possibilities in terms of reducing the weight are also fully exhausted in the case of all-metal basic bodies. 
   An all-plastic basic body is sometimes also used instead of an all-metal basic body for weight optimization, but such chassis parts entail the problem that the plastics used usually tend to undergo brittle fracture. This means that the function of these chassis parts is lost 100% after damage to such a chassis part, whereas complete loss of function does not occur, e.g., in chassis parts made exclusively of metal, even though bending and deformation has occurred. 
   Even though composite materials based on sheet metal-plastic combinations have been known in the manufacture of automobiles from, e.g., the German unexamined patent application DE 38 39 855 A1, the applications proposed there are structural parts for motor vehicle doors, shock absorbers, structural beams, front and rear shells or door sills, in which the sheet metal parts defining the outer shape shall have increased strength or rigidity due to plastic ribbing. None of these lightweight components proposed is, however, suitable for absorbing massive compressive and tensile forces as they occur in chassis parts. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is therefore to develop a force connection strut of a chassis for a passenger car or utility vehicle, which has, on the one hand, the advantage of plastic elements in terms of weight, but, on the other hand, it does not lead to an immediate total loss of its function even in case of damage. 
   According to the invention, a force connection strut of a chassis of a motor vehicle is equipped with an elongated basic body and at least two end-side mount supports for introducing and leading out forces. The basic body is composed of at least one element made of plastic and at least one element made of metal, and the connection between the metal elements and the plastic elements is brought about by the deformation of at least one part of the plastic elements. 
   It can be achieved through this design of a force connection strut that the force connection strut offers a substantial advantage in terms of weight compared with the massive all-metal struts at equal force transmission capacity, on the one hand, and, on the other hand, it prevents an immediate total loss of its function due to the use of metal elements even in case of damage to the plastic structure. 
   It is especially advantageous in this connection for at least one metal element to bridge over the distance between at least two mount supports and to extend preferably over at least one and preferably all mount supports. 
   The deformation of part of the plastic elements, which connect the plastic elements to the metal elements, may be brought about, e.g., by ultrasonic riveting or ultrasonic welding. 
   In the connections between a metal element and a plastic element by means of ultrasonic riveting, the plastic element may advantageously have a plastic pin, which is passed through an opening in the metal from one side, and the projection on the other side of the metal is broadened by the ultrasonic riveting such that a firm connection is established between the metal element and the plastic element. 
   A connection can be achieved between a metal element and a plastic element by welding, e.g., by placing the plastic element from one side on the metal element in the area of an opening in the metal element and putting on a plastic fastening element with a fastening leg and with a locking leg from the other side such that fastening leg is brought into contact with the plastic element through the opening and can be welded to same, preferably by means of ultrasound. 
   According to another special embodiment of the present invention, provisions are made for the basic body to be formed from at least two metal elements lying opposite each other, which are preferably flat sheet metals, which are connected to one another and are held at spaced locations from one another by a plastic element. 
   The metal elements may be, e.g., simple, flat, punched-out sheet metal parts or deep-drawn sheet metal parts or even so-called “tailored blanks.” Especially in the case of the use of “tailored blanks,” there is a very simple possibility of designing the “tailored blanks” in the areas subject to especially high loads such that a thicker material or even a special alloy with a higher strength is used there. The metal element is thus adapted to the specific load. 
   The basic body may have, e.g., the shape of an H or a U, and the individual legs are made partly of plastic or metal depending on the strength requirements and the geometry of the load. 
   Furthermore, the basic body may also comprise according to the present invention a plurality of sheet metals and plastic structures, which are arranged in a plurality of planes directed preferably in parallel and/or at right angles to one another and which are connected to one another in the above-described manner. 
   The basic body may have a single plastic element, which comprises at least two and preferably three of the planes, wherein the sheet metals form the rest of the planes, preferably two or three, which are preferably arranged exclusively in parallel. 
   In another embodiment of the basic body, the basic body may be composed, e.g., of a preferably metallic U-section and a connection element, which preferably consists of plastic and connects the free legs of the U-section at the ends. 
   Moreover, the invention may provide that the plastics used have at least partially fiber reinforcements, wherein the fiber reinforcements may be preferably glass fibers, carbon fibers or aramide fibers. Due to this fiber reinforcement in the plastic, it is now possible to select the percentage of the fibers such that the thermal expansion characteristic of the plastic elements at least extensively corresponds to the thermal expansion characteristic of the metal elements used, at least in the range of the usual operating temperatures of the force connection strut. As a result, stresses that could lead to damage to the force connection strut over a longer period of time because of different coefficients of thermal expansion are prevented from being generated in the composite parts. In addition, deformation of such a composite part could develop due to a different thermal expansion characteristic, or the characteristic in terms of damping or force transmission could change excessively. 
   Concerning the embodiment of the metal elements, the inventors propose that these be manufactured from iron or steel. If an especially lightweight construction is to be produced, the metal elements could also consist of aluminum or an aluminum alloy. 
   Furthermore, it is advantageous to provide the metal elements, at least if they are not manufactured from a corrosion-resistant material themselves, with a corrosion-inhibiting surface protection. Especially if the metal elements are formed by punching or deep drawing, it is especially advantageous to debur these metal elements, because the sharp burs of the metal elements may damage the plastic elements due to metal and plastic elements being placed directly on one another. 
   To additionally reinforce the metal elements or even for additional positive-locking connections between metal elements and plastic elements, the metal elements may also be provided with beads according to the present invention. 
   Furthermore, it may be advantageous for a metal element to have at least one bend in the area of the connection with a plastic element, the bend preferably engaging an opening in the plastic element connected to the metal element. In conjunction with the bends, positive-locking connections can be established between the metal elements and the plastic elements due to these openings. As a result, it is possible to produce, e.g., shapes that correspond to a bent tongue and groove construction, which leads to an additional improvement in the connection between the elements. 
   Finally, the inventors also propose that at least one plastic element have at least one contact surface, preferably in the form of a web or a plurality of webs, in the area of the connection with a metal element. It is achieved due to this design that the assembly of the force connection strut is facilitated, on the one hand, and a better accuracy of shape is also achieved, on the other hand, and forces that are additionally generated, especially torsional forces, can be supported. 
   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 
       FIG. 1   a  is a cross sectional view showing the design of a force connection strut; 
       FIG. 1   b  is another cross sectional view showing the design of a force connection strut with ultrasonic riveting of the plastic element; 
       FIG. 2   a  is a cross sectional view showing the design of a force connection strut; 
       FIG. 2   b  is another cross sectional view showing the design of a force connection strut with ultrasonic welding of the plastic element; 
       FIG. 3  is a cross sectional view showing a force connection strut with a plastic H-section and metal connection struts; 
       FIG. 4  is a cross sectional view showing a force connection strut designed as a U-section; 
       FIG. 5  is a cross sectional view through a force connection strut with a U-section made of metal and connecting plastic section of the free legs; 
       FIG. 6  is a cross sectional top view of a metallic punched part of the connection strut according to the present invention; and 
       FIG. 7  is a cross sectional top view of a deep-drawn metal element of a force connection strut. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings in particular,  FIGS. 1   a  and  1   b  show a cross section through a force connection strut according to the present invention, comprising two flat deep-drawn sheet metals  1  and  2 , which are arranged at spaced locations from and in parallel to each other. A plastic element  3 , which passes through the openings  6  of the two deep-drawn sheet metals  1  and  2  with a sufficient projection with its end-side pins  5 , is arranged between the two deep-drawn sheet metals  1  and  2 , which have an opening  6  each located opposite each other. The plastic elements  3  additionally have a stop  4  each on both sides, which ensures the maintenance of the distance between the deep-drawn sheet metals. 
     FIG. 1   a  shows the state of the above-mentioned arrangement before the ultrasonic riveting, while  FIG. 1   b  shows the state after the ultrasonic riveting. The pins  5  have been deformed here because of the action of the ultrasound, have broadened and form a positive-locking connection between the plastic elements  3  and the two deep-drawn sheet metals  1  and  2 . In the connections being shown, the openings  6 , through which the plastic elements  3  pass, may be arranged either at a plurality of points of small extension, or they may also be elongated holes, so that the ultrasonic riveting becomes effective over a longer section. 
     FIGS. 2   a  and  2   b  show basically the same arrangement of a force connection strut according to the present invention with two deep-drawn sheet metals located opposite each other with an opening  6  each. A plastic element  3 , which has, e.g., the shape of an H, is located between the sheet metals  1  and  2 , so that the sheet metals  1  and  2  lie on the short legs. In addition, a V-shaped groove, which is arranged in the area of the openings  6 , is located in the short leg. 
     FIG. 2   a  additionally shows, still in the separated state, two approximately T-shaped plastic fastening elements  7  with a fastening leg  9  each and with a locking leg  8  arranged at right angles thereto, which are arranged such that the fastening leg  9  extends through the opening  6  in the respective sheet metals  1  and  2  and can be brought into direct connection with the plastic element  3 . 
   Finally,  FIG. 2   b  shows the two plastic fastening elements  7  pushed into the openings  6  and a weld seam  10  prepared by means of ultrasonic welding between the fastening elements  7  and the plastic element  3 , so that a stable fastening is obtained, on the whole, between the two sheet metal parts  1  and  2  and the plastic element  3 . 
   All the sheet metal parts shown here may be designed according to the present invention both as deep-drawn sheet metals, as punched sheet metals or even as “tailored blanks.” In addition, it is also possible to use sheet metals that were manufactured, e.g., by means of forging processes, such as laser cutting, plasma cutting, water jet cutting or torch-cutting. 
     FIG. 3  shows another variant of a design of a force connection strut according to the present invention. This comprises an approximately H-shaped plastic element, which is composed of the central leg  33  and the two peripheral legs  34  and  35 . The central leg  33  is arranged at right angles to the two peripheral legs  34  and  35  arranged in parallel and is rigidly connected to these. The first peripheral leg  34  has a stop  37  each on the inner side, whereas the second peripheral leg  35  has two grooves  36  extending at its edge, which are limited inwardly by two stops  37  and outwardly by a bent end of the leg itself. Two flat punched sheet metals  31  and  32 , which are in contact with the stops  37  of the first peripheral leg  34  on the other side, are pushed into these grooves  36 . If the projection of the first peripheral leg of the plastic H-section  34  is now adapted on both sides by applying ultrasonic or thermal deformation of the contour of the leg  35  located opposite in the edge area, very good positive-locking connection is established between the plastic and metal elements. The positive-locking connection can be additionally improved by providing openings or beads in the metal elements in the area of the deformations. 
     FIG. 4  shows the cross section of another embodiment of a force connection strut according to the present invention. This is composed of two deep-drawn sheet metals  41  and  42  arranged at the edge and two plastic elements  43  and  45  connecting these. The plastic section  43  lying on top has a groove  44  each at its two ends, which can be engaged by the two sheet metals with their ends bent in a rounded shape in a positive-locking manner. The plastic element  45  lying at the bottom has two straps  46  on its top side, which are arranged at an angle of about 45° in relation to the principal plane of the plastic element  45 . These are directly connected to the bent ends of the sheet metals  41  and  42 , e.g., by ultrasonic riveting or ultrasonic beading. In addition, the free straps  47  may also be deformed, so that an even better positive-locking connection is formed with the sheet metal parts  41  and  42 . The sheet metal parts  41  and  42  may have beads and/or openings in the area of the connections in this case as well in order to achieve an optimization of the positive-locking connection between the individual parts fitted together. It may also be advantageous to provide the sheet metals with beads or other corresponding shapes, e.g., during the deep drawing, in other areas that are not in connection with other parts, so that increased torsional rigidity is achieved. 
   It shall also be noted that the plastic element  43  from  FIG. 4  has an arched shape and is as a result able to absorb especially high radial loads. 
   Finally,  FIG. 5  shows a simplified form of the force connection element from  FIG. 4 . A metallic U-section  52  is beveled obliquely at its free ends  53  here. To close the U-section, a plastic element  51 , which has a likewise bent inner strap  54  each at its ends, is attached in a positive-locking manner, and the outer strap  55  is subsequently deformed in a positive-locking manner by the action of ultrasound or heat, so that a rigid connection is established between the metallic U-section  52  and the plastic element  51 . The arrangement of corresponding openings or beads in the connection area is beneficial for strengthening the connection in this case as well. 
   Finally,  FIGS. 6 and 7  show two embodiments of the above-mentioned metal elements.  FIG. 6  shows a flat punched part  61 , which has an opening  62  each at both ends, into which a mount support having the shape of a sleeve is inserted, and two such punched parts, as thy are shown, e.g., in  FIGS. 1   a  and  1   b  as well as  FIGS. 2   a  and  2   b , can be fitted together to form a force connection strut. The openings  63  shown are used now to connect the plastic part arranged between the metal elements with the metal element by ultrasonic riveting or ultrasonic welding. 
   A similar embodiment of a metal element  71  is shown in  FIG. 7 . This likewise has an opening  72  each on both sides, and these openings have a deep-drawn sleeve for the mount support, indicated by the circles drawn in broken lines. In addition, an elongated hole  73 , which is likewise provided to establish the connection with a plastic element, is provided in this deep-drawn sheet metal between the openings  72 . For example, flat lines of the wall of the elongated hole  73  are indicated on the top side, while a wavy course of the side sheet metals of the elongated hole  73  is shown on the underside. Both embodiments may be used, and the wave-shaped side wall ensures an improved positive-locking connection in the longitudinal direction, but it requires an additional effort for shaping the plastic element. 
   The parts made of plastic are additionally designated by K and represented by appropriate crosshatching in the figures shown above, whereas the parts consisting of metal are marked by M and are shown by oblique hatching. 
   Consequently, a non-positive connection is achieved, on the whole, between a chassis and a wheel carrier with the design of a force connection strut of a chassis of a motor vehicle according to the present invention. Such struts can be manufactured with a greatly reduced weight, on the one hand, and also at a very low cost because of the simplicity of the individual elements. 
   While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.