Abstract:
In a wheel support structure of a commercial vehicle including an axle with a jaw structure having two bearing bores and a stub protruding into the jaw structure with a pin extending into the stub and into the bearing bores, the bearing bores are closed adjustably by screw caps threaded into the bearing bores for adjusting the pin position and setting a predetermined moment of friction between the bearing elements.

Description:
This is a Continuation-In-Part Application of international application PCT/EP02/13069 filed Nov. 21, 2002 and claiming the priority of German application 101 61 207.9 filed Dec. 13, 2001. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a steering knuckle pin bearing in an axle of a vehicle, in particular a commercial vehicle, for mounting a steerable vehicle wheel on a vehicle chassis. 
   DE 196 31 946 A1 discloses a steering knuckle pin bearing of this type which has a wheel-side first bearing element which is mounted pivotally on a chassis-side second bearing element. The wheel-side first bearing element has a jaw in which aligned first and second bearing bores are provided. The chassis-side second bearing element has a stub which protrudes into the jaw and receives therein a steering knuckle bearing pin whose axis extends between a first bearing journal and a second bearing journal. By this means, two bearing journals which are aligned with each other are formed on the stub. The first bearing journal is mounted in the first bearing bore via a first bearing while the second bearing journal is mounted in the second bearing bore via a second bearing. Furthermore, the first bearing bore is closed by a screw cap which interacts with a thread and by which the first bearing is axially engaged. For the purpose of installing the steering knuckle pin bearing, the screw cap can be adjusted by screwing on the thread to an extent such that, as a result, between the bearing elements a predetermined moment of friction can be set between the bearing elements. In contrast to this, the second bearing bore is closed by a positionally fixed cover, consequently the relative position between the bearing elements in the axial direction of the bearing journals is determined by the fixed cover and the second bearing supported thereon. 
   U.S. Pat. No. 5,413,365 discloses another steering knuckle pin bearing, in which the first bearing bore can likewise be closed by a screw cap, in which case screwing in of the screw cap enables an outer ring of a conical bearing to be clamped with a predetermined tightening torque against an axial shoulder formed in the bearing bore. This enables the setting of a certain axial pre-stress with which the outer ring comes to bear against the bearing shoulder. As a result, an adjustment of the moment of friction and an adjustment of the relative position between the bearing elements is not possible. 
   A further steering knuckle pin bearing is disclosed in U.S. Pat. No. 1,503,511, in which a conical steering knuckle bearing pin penetrates the stub in an opening of conical design complementary to it. The steering knuckle bearing pin can now be adjusted axially by means of a screw cap in order to axially clamp an outer side of the stub against an inner side of the opening for firm engagement of the bearing pin with the stub. 
   Further steering knuckle pin bearings are disclosed, for example, in DE 199 55 509 A1 and in DE 197 38 113 A1. 
   In a steering knuckle pin bearing, during the installation a predetermined relative position between the two bearing elements has to be set relatively precisely in order thereby to optimize the steering kinematics of the wheel mounting, in particular to enable the steering operation to be optimized as a result. It is also necessary to set a predetermined moment of friction between the bearing elements in order thereby to improve the characteristics of the vehicle-movement dynamics, in particular to avoid a “steering vibration”. The setting of the relative position and of the moment of friction can according to FR 2 576 860 A be realized by a compensating washer or a compensating washer assembly disposed at a suitable point, e.g. axially on or in the associated bearing bore between one of the bearings and its axial support. The determination of the compensating washer which is best suited or of the compensating washer assembly which is best suited is relatively time-consuming. Furthermore, only a predetermined selection of compensating washers of different thickness is available, so that the setting of the desired relative position and of the desired moment of friction is possible only in predefined steps. 
   It is the object of the present invention to provide an improved steering knuckle pin bearing arrangement in which in particular the setting of the relative position and of the moment of friction between the bearing elements are simplified. 
   SUMMARY OF THE INVENTION 
   In a steering knuckle pin bearing of an axle of a vehicle, in particular a commercial vehicle, for mounting a vehicle wheel on a vehicle chassis, wherein a wheel-side bearing element is mounted pivotally on a chassis-side bearing element and one of the bearing elements has a jaw structure in which two bearing bores are formed while the other bearing element has a stub which protrudes into the jaw structure and on which two bearing journals are formed which are mounted in the bearing bores via bearings, the one bearing bore is closed by a screw cap which interacts with a thread and on which the bearing is supported axially, with the screw cap being adjustable to an extent such that a predetermined relative axial position can be set between the bearing elements and the other screw cap being adjustable for setting a predetermined moment of friction between the bearing elements. 
   The invention is based on the general concept of closing the two bearing bores in each case by means of a screw cap in such a way that, during installation, the screw caps can be adjusted in the axial direction of the bearing journals by screwing relative to the bearing bore. With the other bearing journal which is accommodated in the other bearing bore being axially adjustable, the position of the screw cap can be set between the bearing elements in the axial direction of the bearing journals in an infinitely variable and particularly simple manner. If the other bearing bore is closed axially and the bearing accommodated therein or the bearing journal accommodated therein is supported axially, rotation of the screw cap permits adjustment of the moment of friction between the bearing elements in an infinitely variable and particularly simple manner. The relative position and of the moment of friction between the bearing elements can therefore be adjusted with high accuracy and in a simple manner. 
   It is expedient to secure the one screw cap or both screw caps against rotation after they have been adjusted in order to secure the desired settings. 
   In principle, the bearing element including the bearing bores can be provided, at least in the region of one of its bearing bores, with an external thread onto which the associated screw cap can be screwed, the latter then having a corresponding internal thread. However, it is advantageous to provide the particular bearing bore with an internal thread, and the associated screw cap with a corresponding external thread. In this arrangement, the forces to be transmitted via the thread are reduced. In addition, this embodiment is more compact. 
   The invention will become more readily apparent from the following description of preferred embodiments thereof described below with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows in a longitudinal sectional view a steering knuckle pin bearing according to the invention for a driven axle, and 
       FIG. 2  shows in a view as in  FIG. 1 , a steering knuckle pin for a non-driven axle. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in greater detail in the following description, using the same reference numerals when referring to identical or functionally identical or similar components. 
   As shown in  FIGS. 1 and 2 , a steering knuckle pin bearing  1  according to the invention has a wheel-side first bearing element  2  which is connected to a hub  3  of a vehicle wheel (otherwise not shown). A disc brake of the wheel is designated by  4 . This first bearing element  2  is mounted pivotably on a chassis-side second bearing element  5  which is fitted on a vehicle chassis (not shown here). The second bearing element  5  is usually a rigid axle body. A pivot axis about which the two bearing elements  2  and  5  are mounted pivotably on each other is designated by  6 . 
   In the embodiments shown here, the first bearing element  2 , i.e. the wheel-side bearing element  2 , has a jaw  7  while the second bearing element  5 , i.e. the chassis-side bearing element  5 , has a stub  8 . It is clear that, in principle, also the chassis-side second bearing element  5  may be equipped with a jaw, so that the stub is then formed on the wheel-side first bearing element  2 . 
   The jaw  7  has a first bearing bore  9  (illustrated at the bottom in  FIGS. 1 and 2 ) and a second bearing bore  10  (illustrated at the top in  FIGS. 1 and 2 ). The two bearing bores  9  and  10  are positioned on the jaw  7  in such a manner that they are aligned with each other and are arranged co-axially with the pivot axis  6 . The stub  8  protrudes into the jaw  7  and has a first bearing journal  11  (illustrated at the bottom in the figures) and a second bearing journal  12  (illustrated at the top in the figures). The bearing journals  11  and  12  are also arranged on the stub  8  in such a manner that they are aligned with each other and are orientated co-axially with the pivot axis  6 . The first bearing journal  11  is inserted into a cup-shaped first bearing  13  and is mounted via the latter in the first bearing bore  9 . In a corresponding manner, the second bearing journal  12  is also inserted into a cup-shaped second bearing  14  and is mounted via the latter in the second bearing bore  10 . The bearings  13  and  14  each contain a radial bearing  15 , for example in the form of a needle bearing, and an axial bearing  16 , for example in the form of a friction bearing. The bearings  13 ,  14  are expediently fitted in a hermetically sealed manner on the bearing journals  11 ,  12 , so that the bearings  13  and  14  can expediently be designed to be free from maintenance. The two bearings  13  and  14  are designed here as bearing bushings which are closed on one side. 
   The first bearing bore  9  is closed in the axial direction by a first screw cap  17 . In a corresponding manner, the second bearing bore  10  is also closed in the axial direction by a second screw cap  18 . In this case, the first screw cap  17  closes the first bearing bore  9  on an outer side which faces away from the stub  8 . In a corresponding manner, the second screw cap  18  also closes the second bearing bore  10  on an outer side which faces away from the stub  8 . 
   The screw caps  17  and  18  each have an external thread  19  and are equipped axially on the outside with a polygonal stub  20 . For the first screw cap  17 , a first internal thread  21  is provided on the jaw  7  is cut into the first bearing bore  9 . Also for the second screw cap  18 , a second internal thread  22  is provided in a corresponding manner in the jaw  7  and is likewise cut into the second bearing bore  10 . The respective bearings  13  and  14  are supported in the axial direction on these screw caps  17  and  18 . 
   The bearing bores  9  and  10 , have at on their axially outer edges, at least one cutout or notch  23  into which an edge section of the particular screw cap  17 ,  18  protrudes, forming a drive-in lug  24 . As a result, this drive-in lug  24  is in form-fitting engagement with the particular notch  23  in screwing direction of the particular screw cap  17 ,  18 , for securing the screw cap  17 ,  18  against rotation. 
   The threads  21  and  22  and the screw caps  17  and  18  are coordinated with one another and dimensioned with respect to the axial direction of the bearing pins  11 ,  12  in such a manner that an adjustment region is formed for both screw caps  17 ,  18 , in which the screw caps  17 ,  18  can be adjusted in the axial direction of the bearing journals  11 ,  12  at least during the installation of the steering knuckle pin bearing  1 . The axes of the bearing journals  11  and  12  coincide with the pivot axis  6 . Therefore the axes of the bearing journals  11 ,  12  are both designated by the reference numeral  6 . 
   In the embodiment according to  FIG. 1 , the steering knuckle pin bearing  1  is designed for a driven axle or for a driven wheel. In this embodiment, the bearing journals  11  and  12  are separate components which are fastened on the stub  8  of the second bearing element  5 , for example by means of press fitting. In contrast, the steering knuckle pin bearing  1  in  FIG. 2  is a variant for a non-driven axle or for a non-driven vehicle wheel. In this case, the two bearing journals  11  and  12  are formed on a steering knuckle bearing pin  25  which is inserted into an opening  26  in the stub  8 . As a result, the stub  8  extends around, and firmly engages, the steering knuckle bearing pin  25  between the bearing journals  11  and  12 . The steering knuckle bearing pin  25  can be fastened on the stub  8  likewise by means of a press fit and/or by a form-fitting connection. 
   The steering knuckle pin bearing  1  according to the invention can be fitted as follows: 
   The two bearing bores  9  and  10  are initially open. Then, in a customary manner, the stub  8  can be inserted into the jaw  7  and the bearing journals  11  and  12  together with the bearing bushings  13  and  14  can be inserted into the bearing bores  9  and  10 . 
   When the bearing journals  11 ,  12  are inserted, it is possible, for example in the embodiment according to  FIG. 2 , for one of the bearing bores  9 ,  10  to already be closed by the associated screw cap  17 ,  18 . However, the bearing bore  9 ,  10  is expediently closed only after the bearing journals  11 ,  12  have been properly adjusted. 
   After the bearing journals  11 ,  12  are inserted into their bearing bores  9 ,  10 , the relative position of the two bearing elements  2  and  5  is adjusted. In this adjustment operation, one of the bearing bores  9 ,  10 , expediently the lower, first bearing bore  9 , is first closed by the first screw cap  17 . 
   Adjustment of the first screw cap  17  by screwing provides the position adjustment of the first screw cap  17  relative to the first bearing bore  9  in the axial direction  6  of the bearing journals  11 ,  12 . As a result, since the second bearing element  5  is supported on the first screw cap  17  via the first bearing journal  11  and the first bearing  13 , the relative axial position of the second bearing element  5  and the first bearing element  2  is also adjusted. In the embodiment according to  FIG. 1 , the desired relative position corresponds to a position in which a hub axis  27  of the vehicle wheel is aligned with a central axis  28  of a drive shaft  29 . In the embodiment according to  FIG. 2 , the desired relative position is defined by other predetermined parameters; in particular, the hub axes  27  on the opposite sides of the vehicle should be aligned with each other. 
   After determining the desired relative position between the two bearing elements  2  and  5 , the first screw cap  17  can already be rotationally secured, for example by the drive-in lug  24  being driven into the notch  23 . As an alternative, or in addition, the first screw cap  17  may also be cemented or soldered in position. 
   During this adjustment phase for discovering the correct relative position, the second screw cap  18  may already (partially) be screwed into the second thread  22 , in which case, however, care should be taken to ensure that there is no axial contact between the second bearing  14  and the second screw cap  18 . 
   In a subsequent installation phase, the desired moment of friction, which is to prevail during pivoting movements about the pivot axis  6 , between the bearing elements  2  and  5  can now be set. For this purpose, the second screw cap  18  is now inserted, if appropriate, and adjusted by rotating until there is a clamping action which produces the desired moment of friction. When the predetermined moment of friction has been found, the second screw cap  18  may also be secured in a corresponding manner against rotation. 
   In the case of the steering knuckle pin bearing  1  according to the invention, the settings and adjustments can be carried out with a conventional tool, without particular difficulty, in an infinitely variable and, as a result, very precise manner with little time being required. In comparison to conventional steering knuckle pin bearings which have to be set using compensating washers or compensating washer assemblies, the advantages of the steering knuckle pin bearing  1  according to the invention with regard to its fitting capability are obvious. 
   By appropriate dimensioning of the threads  21 ,  22 , the setting regions of the screw caps  17 ,  18  are matched to the manufacturing tolerances or chain of manufacturing tolerances in order to always be able to implement the desired settings.