Abstract:
A bearing assembly includes two rolling-element bearings having inner and outer rings and rolling elements between the rings, the rolling-element bearings being configured to be axially preloaded, at least one of the inner and outer rings including an axially adjustable flange ring forming a flange for the rolling elements, the flange ring having a first section axially slidably mounted on one of the bearing rings and a second section axially adjacent to the first section, the second section including a thread, and the thread being configured to threadably engage a counterthread of a separate component at a location axially spaced from the bearing ring.

Description:
CROSS-REFERENCE 
       [0001]    This application claims priority to German patent application no. 10 2015 212 311.1 filed on Jul. 1, 2015, the contents of which are fully incorporated herein by reference. 
       TECHNOLOGICAL FIELD 
       [0002]    The disclosure relates to a bearing assembly comprising two rolling-element bearings, each including an inner ring and an outer ring as well as rolling elements disposed between the bearing rings, wherein the two rolling-element bearings can be preloaded in the axial direction by relative displacement of the inner rings and/or the outer rings, wherein flanges are disposed on the inner rings and/or on the outer rings, which flanges form an axial stop for the rolling elements, and wherein at least one flange is disposed on the bearing ring such that it is adjustable in the axial direction relative to the bearing ring carrying it. 
       BACKGROUND 
       [0003]    A bearing assembly of the above-described type is known from DE 10 2012 221 297 A1. With this previously known solution it is possible to axially preload two cooperating rolling-element bearings, in particular tapered roller bearings, against each other. The setting of the preload is facilitated here in that the flange is disposed on the bearing ring such that it is adjustable in the axial direction relative to the bearing ring that carries it. A thread serves for this purpose, and the thread is incorporated in the bearing ring so that the flange with a corresponding counterthread can be screwed onto the bearing ring and thus axially adjusted. 
       SUMMARY 
       [0004]    It is still not optimal with the previously known solution that only a small amount of installation space is available for adjusting the bearing preload or a corresponding bearing clearance, so that it is relatively difficult to install the required components and perform the adjustment. 
         [0005]    An aspect of the disclosure is therefore to further develop a bearing assembly of the above-mentioned type such that it is possible to still be able to perform the preloading in the bearing assembly in a precise manner and wherein it is simultaneously ensured that sufficient space is available for the required components. 
         [0006]    A solution to the foregoing problem is characterized in that the flange displaceable relative to the bearing ring—configured as a flange ring—includes a first section that is displaceable on the bearing ring with a sliding seat and that the flange includes a second section, axially adjacent to the first section, that comprises a thread, wherein the thread can be brought into engagement with a counterthread that is incorporated in a separate component, wherein the separate component is disposed axially spaced with respect to the bearing ring. 
         [0007]    Here the second component is preferably disposed directly adjacent to the bearing ring, wherein an end surface of the separate component abuts on an end surface of the bearing ring. 
         [0008]    Here the separate component is preferably configured as a hollow-cylindrical sleeve (with external or internal thread). 
         [0009]    Means are preferably disposed with which the flange ring is axially fixed, or can be axially fixed, on the separate component. According to one preferred embodiment, these means can be formed by a lock nut that is screwed onto the separate component. 
         [0010]    According to an alternative solution the means can also be formed by a part of the second section of the flange ring, wherein this part is, or will be, plastically deformed in the region of the counterthread. In this case it is preferably provided that at least one groove extending in the axial direction is incorporated in the separate component. Here the first section of the flange ring is preferably at least sectionally hardened here, while the second section of the flange ring is at least sectionally unhardened (and thus configured for plastic deformation for the purpose of fixing). Here the hardened region of the flange has preferably been hardened with an inductive hardening. 
         [0011]    The unhardened region of the flange ring ensures a plastic deformability in a simple manner so that, by a hammer blow, for example, material can be driven into the mentioned groove in the separate component. 
         [0012]    A further alternative solution provides that the means are formed by a material-bonded connection, in particular by a soldering, by a welding, or by an adhering. That is, instead of using a lock nut or plastically deforming a portion of the flange ring, a portion of the flange ring can be soldered, welded or adhered to the separate component. The means could also comprise a servo-motor. 
         [0013]    With the mentioned means it is possible to first precisely set the preload of the bearing assembly and then fix the relocatable flange in order to permanently maintain the set preload. 
         [0014]    The two rolling-element bearings are preferably tapered roller bearings. 
         [0015]    The flanges are preferably disposed on the inner rings. Of course it can also be provided in kinematic reversal that the guide-flange ring is disposed on the respective bearing outer rings. Here the counterthread then preferably sits on the flange ring, while a female thread is incorporated in the adjacent separate component. 
         [0016]    The thread used is preferably a fine thread. 
         [0017]    With respect to the seat surface mentioned it is preferably provided that this is tolerance-adjusted with a clearance fit to a counter-seat-surface on the bearing ring; the clearance fit here is preferably embodied narrow. 
         [0018]    One embodiment provides that the adjustable flange is in connection with a drive means, in particular with a motor (servomotor), with which the flange can be rotated relative to the bearing ring. It is thus possible to control or adjust the preload during the operation of the bearing assembly. 
         [0019]    The disclosed solution thus provides that the counterthread onto which the flange ring is screwed is not part of the bearing ring itself but is part of an axially adjacent separate component. The relocating of this counterthread to the adjacent separate component has the advantage that sufficient installation space (both in the axial and in the radial direction) is now available to in particular accommodate a lock nut. However, even if another type of axial fixing of the flange ring on the separate component is provided (i.e., either with the above-mentioned plastic deformation or in another manner such as, for example, by adhering, soldering, or welding—in particular laser welding—of the flange ring to the separate component) this can occur with improved installation-space conditions. 
         [0020]    Another aspect of the disclosure comprises a bearing assembly that includes a shaft having a shoulder, a first rolling-element bearing comprising a first inner ring and a first outer ring and a first set of rolling elements disposed between the first inner ring and the first outer ring. The first inner ring includes a raceway and a slide surface axially adjacent the raceway, and the first inner ring has a first axial end surface and a second axial end surface. The first inner ring is mounted on the shaft with the first axial end surface abutting the shoulder. The assembly also includes a second rolling-element bearing having a second inner ring and a second outer ring and a second set of rolling elements disposed between the second inner ring and the second outer ring, and a separate component mounted on the shaft and abutting the second axial end surface of the first inner ring. The separate component includes a counterthread. The assembly also includes a flange ring comprising a first section slidably mounted on the slide surface and having a first wall configured to guide the first set of rolling elements and a second section axially adjacent the first section, the second section including a thread radially spaced from the slide surface and in threaded engagement with the counterthread, wherein the first and second rolling-element bearings are configured to be axially preloaded. 
         [0021]    The disclosed design of a bearing assembly thus allows a still-simpler setting of the preload of a bearing unit, in particular of a tapered roller bearing unit, via the axial displacement of a guide flange. 
         [0022]    The precise setting of the preload leads in an advantageous manner to reduced bearing friction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Exemplary embodiments of the disclosure are depicted in the drawings: 
           [0024]      FIG. 1  shows in radial section a bearing assembly comprising inter alia two tapered roller bearings preloaded against each other, 
           [0025]      FIG. 2  shows in radial section a shaft section with a tapered roller bearing that is axially preloaded according to a first embodiment of the disclosure, and 
           [0026]      FIG. 3  shows in radial section a shaft section with a tapered roller bearing that is axially preloaded according to a second embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In  FIG. 1  a bearing assembly  1  is depicted that includes two tapered roller bearings  2  and  3 . The two tapered roller bearings  2 ,  3  each have an inner ring  4  or  5  and an outer ring  6  or  7 . Rolling elements  8  or  9  are disposed between the bearing rings. 
         [0028]    The bearing assembly is embodied in a back-to-back arrangement. Flanges  10  and  11  on the inner rings  4 ,  5  limit the movability of the tapered rollers  8 ,  9  in the axial direction a. 
         [0029]    While one of the flanges  10  or  11  of the inner ring  4 ,  5  is formed in a conventional manner as a fixed flange on the inner ring  4 ,  5 , this does not apply to the other flange. This flange is embodied as an adjustable flange, i.e., it can be adjusted on the inner ring in the axial direction. 
         [0030]    For this purpose two preferred solutions are depicted in  FIGS. 2 and 3 . 
         [0031]    It is provided here in all cases that the flange  10  or  11  that is displaceable relative to the bearing ring  4  or  5  is configured as a flange ring, which includes a first axial section  12  and a second axial section  13 . The first axial section  12  is displaceably disposed with a sliding seat  14  on the bearing ring  4  or  5 . The second section  13  of the flange  10  or  11 , formed one-piece with the first section  12 , includes a thread  15 ; in the exemplary embodiments according to  FIGS. 2 and 3  this is configured as an internal thread. A sleeve-shaped separate component  17  is disposed directly adjacent to the bearing ring  4  or  5 . This includes a counterthread  16  that can be brought into engagement with the thread  15  in the flange ring  12 ,  13 , i.e., the flange ring  12 ,  13  can be screwed onto the separate component  17 . As can be seen, the separate component  17  abuts with its end surface  18  on the end surface  19  of the bearing ring  4 ,  5 . 
         [0032]    The separate component  17  itself is fixed on the shaft  24  using a clamping nut  23 . Accordingly the axial position of the abutment surface of the flange ring  12 ,  13  for the rolling elements  8 ,  9  can be adjusted by corresponding screwing-on of the flange ring  12 ,  13 . 
         [0033]    In order to permanently set the axial preload or bearing clearance, means  20 ,  21  are provided for axial fixing the flange ring  12 ,  13  on the separate component. 
         [0034]    In the exemplary embodiment according to  FIG. 2  these means are formed by a lock nut  20  that is screwed onto the separate component  17  against the flange ring  12 ,  13 . 
         [0035]    However, in the embodiment according to  FIG. 3  the flange ring  12 ,  13  is provided with a not-hardened region at its right side, which in the installed state extends axially into the region of a groove  22  that extends in the axial direction a. If the outer side of the flange ring  12 ,  13  (see arrow tip of reference number  21  in  FIG. 3 ) is struck with a hammer, the material in this region will be deformed into the groove  22 . Rotation of the flange ring  12 ,  13  relative to the separate component  17  will then no longer possible so that the set preload or bearing clearance will be retained. 
         [0036]    Accordingly there is the possibility to axially displace the adjustable flange  10 ,  11 , after installation of the depicted bearing assembly  1 , by screwing the adjustable flange  10 ,  11  so far relative to the inner ring  4 ,  5  that a desired preload or bearing clearance arises in the bearing assembly. This can only occur at the point in time when the clamping nut  23  is already screwed onto the shaft  24  and tightened, i.e., when the bearing inner rings  4 ,  5  are fixedly mounted on the shaft  24 . Setting the preload can therefore occur independently of mounting and fixing the bearing inner rings  4 ,  5  on the shaft  24 . 
         [0037]    By turning the adjustable flange  10 ,  11  the desired preload is then therefore set, which as stated can advantageously occur independently of the tightening of the clamping nut  23 . If the desired end position of the flange  10 ,  11  on the inner ring  4 ,  5  is reached it can be fixed by means  20 ,  21 , with which an axial fixing of the flange  10 ,  11  on the inner ring  4 ,  5  is possible. 
         [0038]    The preload circuits A and B shown in  FIG. 1  are separate from each other so that it is possible to first clamp the inner rings  4  and  5 , which is effected by tightening the clamping nut  23 . This is effected with the high clamping force usual and necessary here. Subsequently the actual bearing preload is set very precisely via the adjustable flange  10 ,  11 , and the thread  15 ,  16  is secured with the means  20 ,  21 . 
         [0039]    The forces that need to be introduced via the adjustable flange  10 ,  11  in order to achieve a desired roller preload are usually lower by approximately a power of ten than the forces that are needed to preload the inner rings  4 ,  5 . This allows a specific embodiment of the present disclosure: hereafter in particular in large bearing units, depending on the operating state the flange  10 ,  11  provided with the thread  15  can be axially set, for example, using a servomotor (then of course without fixing with the other means  20 ,  21  described above) such that the optimal preload always prevails in the bearing unit. 
         [0040]    Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved bearing assembly. 
         [0041]    Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. 
         [0042]    All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. 
       REFERENCE NUMBER LIST 
       [0000]    
       
           1  Bearing assembly 
           2  Rolling-element bearing 
           3  Rolling-element bearing 
           4  Inner ring 
           5  Inner ring 
           6  Outer ring 
           7  Outer ring 
           8  Rolling element 
           9  Rolling element 
           10  Flange 
           11  Flange 
           12  First section of the flange/of the flange ring 
           13  Second section of the flange/of the flange ring 
           12 ,  13  Flange ring 
           14  Sliding seat 
           15  Thread 
           16  Counterthread 
           17  Separate component 
           18  End surface of the separate component 
           19  End surface of the bearing ring 
           20 ,  21  Means for axial fixing 
           20  Lock nut 
           22  Groove 
           23  Clamping nut 
           24  Shaft 
         a Axial direction 
         A Preload circuit 
         B Preload circuit