Abstract:
A vehicle wheel with a wheel rim and a solid tire positioned on the wheel rim. The vehicle wheel has an annular upper shell having a first wedge-shaped surface and composed of at least two upper segments. Further, the vehicle wheel includes an annular lower shell composed of lower segments and having an outer circumference having a second wedge-shaped surface. Moreover, the second wedge-shaped surface is structured and arranged in a diametrically opposed manner to the first wedge-shaped surface. Additionally, the annular lower shell is arranged on the rim, the annular lower shell is arranged against the annular upper shell, and the annular upper shell is connected to the solid tire.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application is a U.S. National Stage Application of International Application No. PCT/EP2004/010927 filed Sep. 30, 2004, which published as WO 2006/037353 A1 Apr. 13, 2006, the disclosure of which is expressly incorporated by reference herein in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a vehicle wheel with a wheel rim and a solid tire positioned on the wheel rim. The wheel rim includes an annular lower shell composed of segments and having a wedge-shaped surface on an outer circumference braced against a wedge-shaped surface of an annular upper shell embodied in a diametrically opposed manner to the wedge-shaped surface of the lower shell. The lower shell is arranged on the wheel rim and the upper shell is connected to the solid tire. 
   2. Description of Background Information 
   A vehicle wheel of this type is known from EP 1 312 489 A2. The essential thing with a vehicle wheel of this type is that an annular lower shell composed of segments and having a wedge-shaped surface on the outer circumference is arranged on the rim, which lower shell is braced against an annular upper shell having a wedge-shaped surface embodied in a diametrically opposed manner, which upper shell is firmly connected to the solid tire. 
   The advantage of a vehicle wheel of this type is that the solid tire that is fixedly arranged on the upper shell can be mounted on the lower shell and thus on the rim with the simplest device. A simple torque wrench is sufficient for mounting a tire of this type on a rim, while otherwise heavy-weight presses are used with all known solid tires for industrial purposes in order to press the solid tire directly onto the rim. However, suitable presses for pressing solid tires onto the rims are heavy and expensive and not available everywhere, so that it is difficult to have a new solid tire mounted onto a rim when needed, since long distances to a workshop equipped with a press of this type often have to be tolerated. 
   A construction known from EP 1 312 489 A2 can already overcome these disadvantages, since through the construction of segmented lower shell and one-piece upper shell with a tire vulcanized thereon, the simplest fitting is possible that can be carried out virtually anywhere. 
   Nevertheless, certain disadvantages have become apparent with a construction according to EP 1 312 489 A2, which are to be overcome through this invention. 
   The influence of heat on the construction of lower/upper shell has proven to be particularly problematic, in that, e.g., at high temperatures as a consequence of outer or inner temperature increases the upper shell has a tendency to undergo thermal expansion, through which a frictional contact between the upper and lower shell is not guaranteed in every case. The solid tire then begins to turn on the rim or on the lower shell. 
   SUMMARY OF THE INVENTION 
   This problem is solved in a surprisingly simple manner in the above-described vehicle tire with an upper shell composed of at least two, and preferably three to five segments. According to the invention, a vehicle wheel known from EP 1 312 489 A2 can be formed such that the upper shell is assembled from at least two segments. 
   It has surprisingly been shown that the problem of the thermal expansion in particular can be solved in that the upper shell, like the lower shell, is composed of segments, namely of at least two segments, preferably of three to five segments. It is thus possible to get control of the thermal problems, in particular by assembling the segments of the upper shell so that expansion joints remain between the segments, which joints are able to equalize the thermal expansion. 
   It has been shown that the embodiment of the upper shell as a segmented upper shell entails other constructive advantages and embodiment possibilities. For example, it is possible to connect the segmented upper shell and the segmented lower shell by a positive connection, namely preferably through an embodiment of the radial congruent contours of upper shell and lower shell by a polygon or by a toothing. 
   Since the rubbing surfaces of the wedge-shaped shells (upper shell and lower shell) should have the lowest friction coefficient due to simple fitting and dismantling, but need to transfer high forces during braking and acceleration in terms of the longitudinal forces, a form closure of this system is particularly advantageous. The form closure is achieved by x-fold polygons, a toothing, a tongue-groove system or through a bayonet lock. 
   Furthermore, an embodiment of the upper shell in segmented form offers the advantage of providing it with an axial locking, e.g., in tongue and groove form, and a radial locking which in particular has the advantage that an improper torquing of the screw joint does not lead to a breaking of the belt of the solid tire arranged on the upper shell. 
   Furthermore, it can be expedient to provide the radially outer contour of the upper shell axially outside with a domed shoulder so that the radially outer contour of the upper shell as a whole has the form of a saddle. An embodiment of this type has proven to be advantageous since it counteracts the stress cracks occurring with high applied axle loads in the base area of the solid tire. 
   In practical embodiments of the invention it can be further advantageous to provide the upper shell and lower shell with diametrically opposed offsets. These offsets serve as a defined stop, so that the screw joint of upper and lower shell can be tightened only up to a defined point, which was not the case with purely conical surfaces according to EP 1 312 489 A2. Alternatively, it can also be advantageous to guide the screws respectively in one or two spacer sleeves which likewise have the purpose of a defined stop. Other known stop possibilities are likewise conceivable. 
   In order to design the fitting of upper and lower shell as simply as possible, it can be advantageous to provide the segments respectively of the lower shell and the upper shell with an arresting system or a click system on their face edges. Hereby, e.g., a face edge can be provided with a hook-like pin that engages in a corresponding recess in an end face of another segment and locks in place there. The fitting of the lower shells onto the rim is thereby made extremely easy in that the segments of the lower shell are simply placed on the compression rubber of the rim and connected to the other segments by the arresting connection so that a laborious and lengthy handling is avoided. 
   In a further practical embodiment, it can be advantageous to install pressure cases of a metallic material in the segments of the upper shell or lower shell, which on the one hand reduce the surface pressure, and on the other hand provide a collision guard for the segments preferably comprising plastic and the screw heads. 
   In another advantageous embodiment of the invention, it can be advantageous to give the vehicle tire an antistatic finish. In particular when upper and lower shell are made of plastic, the problem can occur that a static charge of the tire can be hard to dissipate. It can hereby be provided that a metal belt of the solid tire is electrically connected to at least one screw that connects the upper and lower shell, whereby the screw is electrically connected to the rim of the vehicle wheel. A connection of this type of the belt via the screw to the rim can be made in an extremely simple manner, e.g., in that a wire is connected to the belt and to a metallic pressure case of the screw, whereby the screw can be connected to the rim via a plain washer or another wire. 
   In another advantageous embodiment of the invention, it can be provided that the solid tire is vulcanized onto the upper shell composed of segments. Alternatively, it can be provided that the solid tire is a separate component that by the bracing of upper shell with lower shell is connected thereto, whereby in the braced condition an axially outer and upper edge of the lower shell is aligned with an axially outer and upper edge of the upper shell. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages and embodiments of the invention are explained in more detail based on the drawings and the claims. The drawing shows, in each case true to scale: 
       FIG. 1  An exemplary embodiment of a vehicle wheel according to the invention in perspective view; 
       FIG. 2  A detail from  FIG. 1  in perspective view; 
       FIG. 3  An upper shell of a vehicle wheel from  FIGS. 1 and 2  from the side; 
       FIGS. 4   a - 4   g  A pressure case of an upper shell from  FIG. 3  in various views; 
       FIGS. 5   a ,  5   b  Perspective views of two segments of the upper shell of the vehicle wheel from  FIG. 1 ; 
       FIGS. 6   a ,  6   b  Perspective views of two lower shell segments in alternative embodiment; 
       FIG. 7  A perspective partial sectional view of another embodiment of a vehicle wheel; 
       FIG. 8  A radial section through another embodiment of a vehicle wheel according to the invention; and 
       FIG. 9  A radial section through another embodiment of a vehicle wheel according to the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a first exemplary embodiment of a vehicle wheel  1  according to the invention in perspective view. The vehicle wheel  1 , which is preferably used for fork lift trucks, earth-moving machinery, heavy-duty vehicles or similar slow-moving vehicles with high axial load, comprises a solid tire  2  that is connected to a rim  5  by an upper shell  3  and an lower shell  4 . 
   The bond of upper (radially outer) shell  3  and lower (radially inner) shell  4  is shown in more detail in a perspective view in  FIG. 2 . The upper shell  3  comprises three segments  6   a ,  6   b  and  6   c ; the lower shell  4  is likewise composed of three segments  7   a ,  7   b  and  7   c . The segments  6   a  through  6   c  of the upper shell  3  are connected by a positive connection to the segments  7   a  through  7   c  of the lower shell  4  in that the radially inner contour  8  of the upper shell  3  and the radially outer contour  9  of the lower shell  4  have the shape of a polygon. The segments  6   a  and  6   b  of the upper shell  3  have a toothing  10  that is used for the axial locking of the segments  6   a  and  6   b . This locking has proven to be practical in particular when upper shell  3  and lower shell  4  are not braced with one another in a crossed-over manner. The toothing thereby helps so that the segments cannot drift apart axially, then resulting in a danger that a solid tire  2  vulcanized on the upper shell  3  could become detached from the upper shell  3 ; 
   An expansion joint  11  is arranged between the segments  6   a - 6   c  of the upper shell  3 , which can be seen particularly clearly between segments  6   c  and  6   a ; accordingly an expansion joint  12  is arranged between the segments  7   a - 7   c  of the lower shell  4 , which can be seen particularly between segments  7   c  and  7   a . The expansion joints  11  and  12  serve to balance thermal expansions when the vehicle wheel  1  is heated during operation or during high outside temperatures. Through the embodiment of the expansion joints  11  and  12  of the configuration shown in  FIGS. 1 and 2 , it is ensured that lower shell  4  and upper shell  3  hold together under various temperature conditions. 
     FIG. 3  shows the upper shell  3  from  FIG. 2  from the side. It is possible to discern here in particular the inner contour  8  embodied as a polygon, the expansion joint  11  and bores  13  in which screws for bracing against the lower shell  4  can be inserted. Recesses  14  are respectively sunk around the bores  13 , into which recesses pressure cases  15  are inserted. The pressure cases  15  are shown in  FIGS. 4   a  through  4   g  from below, from above, in a perspective view from above and below and in sectional representations in a self-explanatory manner. The pressure cases  15  can be composed of metallic materials, in particular of diecast aluminum or zinc die-casting, or of glass fiber reinforced plastic. The upper shell  3  and the lower shell  4  are composed respectively of plastic, in particular of polyamide. The pressure cases are used to better distribute the pressure exerted by the screws on the upper shell  3  and the lower shell  4 . 
     FIGS. 5   a  and  5   b  show two segments  6   a  and  6   c  of the upper shell in a perspective view. The toothing  10  and a dirt guard  16  can be discerned in particular there. The dirt guard  16  serves a self-cleaning purpose in that dirt that has possibly penetrated into the segment separation joints during thermal expansion can be pressed out again. Furthermore,  FIG. 5   b  shows a stop edge  17 , which will be discussed in detail later. 
     FIGS. 6   a  and  6   b  show segments  7   a  and  7   b  of the lower shell  4 , which segments have congruent mating surfaces to the segments  6   a  and  6   c  of the upper shell  3  shown in  FIGS. 5   a  and  5   b . The segment  7   b  has a click-stop element  18  that interacts with a click-stop element  19  shaped accordingly of the segment  7   a . This renders possible a simple assembly of the segments  7   a ,  7   b  and  7   c  on the rim, in that the individual segments  7   a  through  7   c  are simply placed on a compression rubber on the rim  5  and engaged with one another. 
     FIG. 7  shows a rim  5  on which a segment  7   a  of the lower shell  4  and a segment  6   a  of the upper shell  3  is placed, whereby in addition a partial section of a solid tire  2  can be seen. Just like the lower shell segments  7   a  and  7   c  shown in  FIGS. 6   a  and  6   b , the segments  6   a - 6   c  of the upper shell  3  are provided with click-stop elements  20 ,  21  which are used for the simple joining of the segments  6   a - 6   c  and in addition the radial and axial locking. 
     FIG. 8  shows another exemplary embodiment of a vehicle wheel  1  according to the invention in a radial section. The lower shell  4  and the upper shell  3  are braced against one another by a screw  22 , whereby the screw  22  is supported in pressure cases  15 , whereby a nut  23  is supported in a pressure case  15  of the lower shell  4 . Additionally,  24  indicates a metallic belt. The stop edge  17  of the upper shell  3  abuts against a corresponding stop edge  25  of the lower shell  4 . A radially upper and axially outer surface  26  is embodied such that it is aligned at the same height with a radially upper and axially outer surface  27  of the lower shell  4 . This embodiment makes it possible to use a solid tire  2  that is not connected to the upper shell  3  by vulcanization, but is tensioned on the rim by the upper shell  3  and the lower shell  4  as a separate component and is thus supported. This makes it possible to use the upper shell  3  as a separate component without it being necessary to convey the upper shell  3  to another vulcanization when a solid tire  2  is replaced. 
     FIG. 9  shows another exemplary embodiment of a vehicle wheel according to the invention in a radial section. The vehicle wheel  1  shown in  FIG. 9  thereby largely corresponds to the embodiment shown in  FIG. 8 , whereby, however, in contrast to the embodiment shown in  FIG. 8 , the solid tire  2  is firmly joined to the upper shell  3 , namely by vulcanization. In order to counteract stress cracks with high applied loads, radially upper and axially outer areas of the upper shell  3  are provided with a spherical shoulder  28 , through which the radially outer contour of the upper shell  3  as a whole is given the shape of a saddle  29 . This counteracts stress cracks that can occur with high axle loads. 
   Furthermore, the belt  24  has a connection  30  to the screw  22 , whereby this connection  30  to the screw  22  is used for dissipating electrostatic discharges, resistance&lt;10 6  Ohm, over the rim  5 . Furthermore, if the screw  22  does not have a connection to the rim  5  via the pressure case  15 , furthermore a corresponding connection can be provided from the screw  22  to the rim  5 . If the upper shell  3  and lower shell  4  are made of plastic, such as polyamide, the dissipation of static discharges can also be carried out in that electrically conducting carbon black is mixed into the plastic. 
   Finally, in  FIG. 9  the compression rubber  31  known per se can be briefly discerned, with which preferably a force-closed connection of the lower shell  4  to the rim  5  is obtained. 
   LIST OF REFERENCE NUMBERS 
   Part of the Specification 
   
       
         1  Vehicle wheel 
         2  Solid tire 
         3  Upper shell 
         4  Lower shell 
         5  Rim 
         6   b ,  6   c  Segments 
         7   b ,  7   c  Segments 
         8  Radially inner contour 
         9  Radially outer contour 
         10  Toothing 
         11  Expansion joint 
         12  Expansion joint 
         13  Bore 
         14  Recess 
         15  Pressure case 
         16  Dirt guard 
         17  Stop edge 
         18  Click-stop element 
         19  Click-stop element 
         20  Click-stop element 
         21  Click-stop element 
         22  Screw 
         23  Nut 
         24  Belt 
         25  Stop edge 
         26  Surface 
         27  Surface 
         28  Shoulder 
         29  Saddle 
         30  Connection 
         31  Compression rubber