Abstract:
The invention relates to a vehicle steering wheel comprising a skeleton made of die cast material, a reinforcement being embedded in the die cast material.

Description:
TECHNICAL FIELD  
         [0001]    The invention relates to a vehicle steering wheel.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vehicle steering wheels typically comprise skeletons that are produced increasingly from die cast material, in order to be able to manufacture the increasingly complicated shapes of the skeleton at all and in order to keep the weight as low as possible.  
         BRIEF SUMMARY OF THE INVENTION  
         [0003]    The invention provides a vehicle steering wheel comprising a skeleton which, with a low weight as before, has a higher strength than was known hitherto. This is achieved in a vehicle steering wheel comprising a skeleton made of die cast material, a reinforcement being embedded in the die cast material. This means that the reinforcement is preferably completely embedded into and surrounded by the die cast material, not attached to it from the exterior, for instance, so that no complicated manufacture is necessary. Further, the reinforcement holds die cast portions permanently together. The reinforcement is preferably a one-piece sheet metal having a higher tensile and flexural strength than the die cast material.  
           [0004]    Preferably the reinforcement has through openings which are penetrated by the die cast material, so that a mechanical, form-fitting anchoring of the reinforcement in the die cast material is achieved at numerous sites. Also, a detaching of the die cast material from the reinforcement on fracture of the die cast material can therefore be prevented, irrespective of the fracture site.  
           [0005]    The die cast material is preferably aluminum or magnesium and the metal sheet is steel or aluminum. With a metal sheet of aluminum or a reinforcement of aluminum, the advantage exists in addition that on recycling no separation of the aluminum reinforcement and of the aluminum die cast metal or magnesium die cast metal is necessary. Furthermore, the aluminum surface will slightly dissolve on inflow of the hot aluminum or magnesium, so that a type of solution composite is produced, which in addition to the mechanical anchoring of the reinforcement in the die cast metal provides an additional connection.  
           [0006]    The skeleton has a hub section and at least one spoke originating therefrom. The reinforcement runs from the hub section as far as into the spoke; it can even run into the region of the steering wheel rim. As the fracture of a steering wheel preferably takes place at the transition of the spoke to the hub section, the reinforcement is provided in the particularly critical region of the steering wheel.  
           [0007]    For this purpose, with the use of a metal sheet, provision is made that this has an annular part, extending axially and surrounding an opening in the hub section, and has a flat section originating from the annular part and comprising extensions protruding into the spokes. The annular part surrounds the hub and increases the stability of the hub, so that the metal sheet not only reinforces the transition from the hub section to the spoke, but the hub section itself. Therefore, less die cast material can be provided in the region of the hub section, which is advantageous in terms of reduction in weight. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 shows a perspective view of a skeleton of the vehicle steering wheel according to the invention;  
         [0009]    [0009]FIG. 2 shows a top view onto a metal sheet which is embedded into the skeleton according to FIG. 1;  
         [0010]    [0010]FIG. 3 shows a side view of the metal sheet of FIG. 2; and  
         [0011]    [0011]FIG. 4 shows a sectional view through a part of the skeleton of FIG. 1 in the region of the hub section and of a spoke.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    In FIG. 1 a vehicle steering wheel is illustrated, more precisely its skeleton, which has various sections, namely a rim  10 , spokes  12  and a hub section  14 , from which the spokes  12  originate. The hub section  14  has, in addition, a central opening  16  to subsequently receive a steering column. The skeleton consists of aluminum- or magnesium die cast material.  
         [0013]    A metal sheet  18  illustrated in FIGS. 2 and 3 forms a reinforcement which is embedded in the die cast material, as can be seen more precisely from FIG. 4. The metal sheet  18  has an annular part  20  extending axially (axially means in the direction of the imaginary axis  30  of the opening  16 ) and surrounding the opening  16  in the hub section  14 , and a flat section  22  originating from the annular part and comprising extensions  24  which are slightly bent following the shape of the spokes. The metal sheet  18  is produced by stamping and subsequent deep-drawing. The metal sheet  18  has a plurality of through openings  26  both in the region of the annular part  20  and also in all other sections. Three holding pins  28  which lie around the axis  30  at a 120° distance from each other, are pressed into openings and serve to hold the metal sheet in a die casting mold, so that the metal sheet  18  has the desired distance from the inner side of the mold. Hence, the metal sheet which consists of steel or aluminum is positioned in the die casting mold by means of the pins  28 . Then aluminum or magnesium is introduced, which completely surrounds the metal sheet, so that the latter is embedded in the die cast material, as FIG. 4 shows. The pins  28  can, but do not have to, be removed. As the die cast material also penetrates the openings  26 , a good mechanical binding of the metal sheet  18  into the die cast material is produced, which is given the reference number  36  in FIG. 4.  
         [0014]    The skeleton which is manufactured in this way offers a vehicle steering wheel, which does not allow any free parts to arise.  
         [0015]    The metal sheet  18  is approximately 1 mm thick if it is of steel, and is approximately 2 mm thick if it is of aluminum.