Patent Publication Number: US-2023151849-A1

Title: Rolling element bearing, more particularly slew ring

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase of PCT Appin. No. PCT/DE2021/100085, filed Jan. 29, 2021, which claims the benefit of German Patent Appin. No. 10 2020 109 150.8, filed Apr. 2, 2020, the entire disclosures of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to a rolling element bearing, which is particularly advantageous for use as a slew ring on ceiling pendants in the medical field. 
     BACKGROUND 
     Ceiling pendants, such as ceiling supply units, monitor supports, so-called spring arms or central axes in an operating theater or intensive care unit, usually have one or more supports that are rigidly arranged or height-adjustable with respect to a vertical position, by means of which a medical device attached thereto can be moved and positioned. Supply units are often mounted on the ceiling pendants, using which medical-electrical end devices can be supplied with the media required during an operation, for example. In this regard, the supports define a radius of action of the medical device in which the medical device is positioned. The supports can usually be rotated around at least one slew ring, in particular a rolling element bearing. Optionally, the supports are also height-adjustable and/or arranged such that they can be pivoted in height about an at least approximately horizontally aligned axis. A rotational movement of individual supports, be it an absolute rotational movement or a rotational movement relative to another support, should in many cases be limited to a given angle. This can prevent, for example, one support from being rotated by more than a maximum permissible angle with respect to another support, thereby twisting, crushing or even tearing off cables routed inside the support. A limitation of the angle of rotation can be provided, for example, in the form of a stop against which a support strikes at a certain angle of rotation. Although such a limitation of the angle of rotation can ensure that a maximum angle of rotation is not exceeded, in most designs this also has the disadvantage that only a maximum angle of rotation of 360° can be realized, thus limiting the freedom of movement of the ceiling pendant. If an angle of rotation of about 400° is to be realized, the ceiling pendant has to be rotated back from a 360° position over an angle of rotation of 320° with great effort. 
     A rolling element bearing suitable for use in a ceiling pendant as a slew ring with a stop means for limiting the angle of rotation beyond 360° is known, for example, from DE 10 2006 055 581 A1. This rolling element bearing consists of an inner bearing ring, an outer bearing ring and a plurality of rolling elements, which roll between the bearing rings on inner and outer raceways, wherein an angle-of-rotation limiting device is arranged within the rolling element bearing, which limits the relative rotation between the inner bearing ring and the outer bearing ring within an angle-of-rotation range from 0° to &gt;360° and comprises a first stop element arranged on the inner bearing ring and a second stop element arranged on the outer bearing ring. The angle-of-rotation limiting device is designed as a cam control, which is formed by a spiral-shaped control groove arranged in a side surface of the outer bearing ring as a first stop element and a stop pin axially movable in a slotted groove in a side surface of the inner bearing ring as a second stop element. 
     Another slew ring with a stop means for limiting the angle of rotation beyond 360° is known from DE 10 2007 003 970 A1. In this slew ring formed by a double-row angular contact roller bearing, the bearing outer ring is provided on its inner lateral surface with a circumferentially extending clearance, which is delimited at its two ends by a first stop lug. The bearing inner ring is provided on its outer lateral surface with a guide groove extending in the circumferential direction, which is delimited at its two ends by a second stop lug, wherein a guide element is arranged in the guide groove which connects the two bearing rings to one another in a form-fitting manner. The possible angle of rotation is thus composed of an addition of the angular range of the clearance in the bearing outer ring with the angular range of the guide groove in the bearing inner ring, so that this can reach a maximum of 720° minus the circumferential expansion of both stop lugs. 
     Finally, DE 10 2013 207 783 A1 discloses a slew ring with a stop means for limiting the angle of rotation beyond 360°, which is also designed as an angular contact roller bearing with two rows of rolling elements arranged in an O arrangement relative to one another and in which the stop elements of the angle-of-rotation limiting device are each arranged axially between the inner and outer raceways of the bearing rings. The stop elements of the angle-of-rotation limiting device are formed by a spiral-shaped raceway with one or two stops that can be screwed into the raceway and by a lug that projects into the raceway between the stops. Since the spiral design of the raceway eliminates the restrictions that apply to purely circular raceways, it is also possible to realize angles of rotation of more than 360°. 
     However, a disadvantage of the above-mentioned known slew rings is that the angle-of-rotation limiting devices for realizing angles of rotation greater than 360° are usually very costly to manufacture and/or require more installation space, which causes a further increase in manufacturing costs. 
     SUMMARY 
     Due to the disadvantages of the solutions of the known prior art, the disclosure is therefore based on the object of designing a rolling element bearing, in particular a slew ring, in which a limitation of the angle of rotation greater than 360° is possible by simple and space-saving means while at the same time keeping manufacturing costs low. 
     According to the disclosure, this object is achieved with a rolling element bearing having a first stop element of the angle-of-rotation limiting device, which first stop element is arranged on the inner bearing ring, is formed by a plurality of individual radial base bores arranged in peripheral succession in a row on the outer lateral surface of the inner bearing ring and by at least one slotted-hole-type radial base groove arranged between a first radial base bore and a last radial base bore, and that one or two separate angle limiters protruding radially beyond the radial base bores or the radial base groove can be inserted into the radial base bores or the radial base groove depending on the size of the angle of rotation to be limited and that the second stop element of the angle-of-rotation limiting device, which second stop element is arranged on the outer bearing ring, is formed by a pivoting finger, which is fastened to the inner lateral surface of the outer bearing ring, extends to the radial base bores or the radial base groove in the inner bearing ring and is in stop connection with the angle limiters inserted into the radial base bores or into the radial base groove. 
     Preferred embodiments and advantageous further developments of the rolling element bearing according to the disclosure are described below and in the claims. 
     According to one aspect, the rolling element bearing according to the disclosure is preferably designed as an angular contact roller bearing with two rows of rolling elements arranged in an O arrangement relative to one another, and the stop elements of the angle-of-rotation limiting device are each arranged axially centrally between the inner and outer raceways, respectively, of the bearing rings. Needle rollers, cylindrical rollers or tapered rollers have proved particularly suitable as rolling elements for the rolling element bearing. However, it would also be conceivable to design the rolling element bearing as a double-row angular contact ball bearing in an O or X arrangement. It is also conceivable for the stop elements of the angle-of-rotation limiting device to be arranged axially off-center between or on one side next to the raceways of the bearing rings. 
     According to another aspect, it is a further feature of the rolling element bearing designed that the angle limiters that can be inserted into the radial base bores or the radial base groove in the inner bearing ring are formed by one or two bearing balls corresponding to the diameter or the width of the radial base bores or the radial base groove. However, it is also possible to use one or two cylindrical rollers corresponding to the diameter or width of the radial base bores or the radial base groove as angle limiters, which are inserted into the radial base bores or the radial base groove with one of their end faces first. 
     According to another aspect, the rolling element bearing is further characterized in that the pivoting finger fastened to the inner lateral surface of the outer bearing ring and extending to the radial base bores or the radial base groove is formed by a threaded pin screwed into a continuous threaded bore in the outer bearing ring. Alternatively, a dowel pin pressed into a through hole can be used as a pivoting finger. In this regard, the threaded pin is screwed in or the dowel pin is pressed in in such a manner that the pivoting finger protrudes beyond the inner lateral surface of the outer bearing ring only to the extent that it does not touch the outer lateral surface of the inner ring at the level of the radial base bores or the radial base groove. 
     According to another aspect, a further feature of the rolling element bearing is that the radial base bores arranged in peripheral succession in a row on the inner bearing ring enable limitation of the angle of rotation in a range of up to 320° and the radial base groove arranged between the first radial base bore and the last radial base bore is provided for limitation of the angle of rotation in a range of up to 400°. However, if more or fewer radial base bores are arranged in succession and/or the length of the radial base groove is varied, smaller or larger ranges of the angle of rotation limitation are also possible. 
     Finally, the rolling element bearing according to the disclosure is further characterized in that, for limiting the angle of rotation in a range of up to 340°, two angle limiters are inserted in two correspondingly spaced apart radial base bores or in a radial base bore and in the radial base groove, and the pivoting finger is movable between the one side of the one angle limiter and the other side of the other angle limiter. For limiting the angle of rotation in a range between 350° and 400°, on the other hand, only a single angle limiter is inserted in one of the radial base bores or in the radial base groove, such that the pivoting finger is movable between one side and the other of the one angle limiter. In this regard, an angle limiter inserted in the radial base groove is displaced by the pivoting finger from one end of the radial base groove to its other end. 
     The rolling element bearing according to the disclosure thus provides the advantage over the rolling element bearings for a slew ring known from the prior art that it is formed by a plurality of individual radial base bores arranged in peripheral succession in a row on the outer lateral surface of the inner bearing ring and by at least one slotted-hole-type radial base groove arranged between a first radial base bore and a last radial base bore as well as by a pivoting finger fastened to the inner lateral surface of the outer bearing ring and extending to the radial base bores or to the radial base groove in the inner bearing ring with a device for limiting the angle of rotation greater than 360°, which consists of simple and space-saving means and can be manufactured at low cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the rolling element bearing designed according to the disclosure is explained in more detail below with reference to the accompanying drawings. In the figures: 
         FIG.  1    shows a side view of a rolling element bearing according to the disclosure; 
         FIG.  2    shows the cross-section A-A through the rolling element bearing according to  FIG.  1   ; 
         FIG.  3    shows a side view of the inner ring of the rolling element bearing according to the disclosure according to  FIG.  1   ; 
         FIG.  4    shows the cross-section C-C through the inner ring of the rolling element bearing according to the disclosure according to  FIG.  3   ; 
         FIG.  5    shows the partial section B-B through the rolling element bearing according to  FIG.  1   ; 
         FIG.  6    shows a perspective view of the inner ring of the rolling element bearing according to the disclosure according to  FIG.  1   ; and 
         FIG.  7    shows a schematic cross-sectional view of the rolling element bearing according to  FIG.  1    in an initial position, a middle position and an end position of the outer bearing ring when the angle of rotation is adjusted by 400°. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIGS.  1  and  2    clearly show a rolling element bearing  1  suitable for use as a slew ring in a ceiling pendant, which is designed as an angular contact roller bearing and consists of an inner bearing ring  2 , an outer bearing ring  3  and a plurality of rolling elements  4 , which are designed as needle rollers arranged in two rows in an O arrangement relative to one another and roll between the bearing rings  2 ,  3  on inner and outer raceways  5 ,  6  and  7 ,  8 .  FIG.  2    also shows that an angle-of-rotation limiting device  9  is arranged within the rolling element bearing  1 , which limits the relative rotation of the inner bearing ring  2  with respect to the outer bearing ring  3  within an angle-of-rotation range from 0° to greater than 360°. This angle-of-rotation limiting device  9  comprises a first stop element  10  arranged on the inner bearing ring  2  and a second stop element  11  indicated in  FIG.  1    and arranged on the outer bearing ring  3 , wherein both stop elements  10 ,  11  are each arranged axially centrally between the inner and outer raceways  5 ,  6  and  7 ,  8 , respectively, of the bearing rings  2 ,  3 . 
       FIGS.  3 ,  4  and  6    further show that the first stop element  10  of the angle-of-rotation limiting device  9  arranged on the inner bearing ring  2  is formed by a plurality of individual radial base bores  13  arranged in peripheral succession in a row on the outer lateral surface  12  of the inner bearing ring  2  and by a slotted-hole-type radial base groove  14  arranged between a first radial base bore  13   a  and a last radial base bore  13   b,  wherein one or two separate angle limiters  15  protruding radially beyond the radial base bores  13  or the radial base groove  14  can be inserted into the radial base bores  13  or the radial base groove  14  depending on the size of the angle of rotation to be limited. The angle limiters  15  are clearly formed by one or two bearing balls whose diameter corresponds to the diameter of the radial base bores  13  or the width of the radial base groove  14 , respectively. 
     The second stop element  11  of the angle-of-rotation limiting device  9 , which is arranged on the outer bearing ring  3 , is formed on the opposite side by a pivoting finger  17 , which is visible in the sectional view in  FIG.  5   , fastened to the inner lateral surface  16  of the outer bearing ring  3 , which is formed by a threaded pin screwed into a continuous threaded bore  18  in the outer bearing ring  3 . This pivoting finger  17  clearly extends to the radial base bores  13  or the radial base groove  14  in the inner bearing ring  2  and is in stop connection with the angle limiters  15  inserted in the radial base bores  13  or the radial base groove  14 . 
       FIGS.  6  and  7    also show that the radial base bores  13  arranged in peripheral succession in a row on the inner bearing ring  2  enable limitation of the angle of rotation in a range of up to 320° and that the radial base groove  14  arranged between the first radial base bore  13   a  and the last radial base bore  13   b  is provided for limitation of the angle of rotation in a range of up to 400°. For limiting the angle of rotation in a range of up to 340°, two angle limiters  15  are inserted in two correspondingly spaced apart radial base bores  13  or in a radial base bore  13  and in the radial base groove  14  so that the pivoting finger  17  is movable between the one side of the one angle limiter  15  and the other side of the other angle limiter  15 . For limiting the angle of rotation in a range between 350° and 400°, on the other hand, only a single angle limiter  15  is inserted in one of the radial base bores  13  or in the radial base groove  14 , such that the pivoting finger  17  is movable between one side and the other of the one angle limiter  15 . 
     Finally, the schematic cross-sectional illustrations of the rolling element bearing  1  in  FIG.  7    show by way of example the movement of the pivoting finger  17  of the angle-of-rotation limiting device  9  or of the outer bearing ring  2 , respectively, when the angle of rotation is adjusted by 400°. The left illustration shows the initial position of the rolling element bearing  1 , in which a single bearing ball is inserted as an angle limiter  15  in the radial base groove  14  in the stationary inner bearing ring  2  in such a manner that it rests against the left end of the radial base groove  14  and the pivoting finger  17 , which is designed as a threaded pin, on the outer bearing ring  2  is in contact with the right side of the angle limiter  15  in an 11 o&#39;clock position. 
     After a clockwise rotation of the outer bearing ring  3  by approx. 200°, the pivoting finger  17  on the outer bearing ring  3  is in a middle position corresponding to the middle illustration of  FIG.  7   , which approximately corresponds to a 6 o&#39;clock position. 
     With further rotation of the outer bearing ring  3 , the pivoting finger  17  then strikes the left side of the angle limiter  15  in the radial base groove  14  at an angle of rotation of about 350° and displaces it within the radial base groove  14  by a further 50° from its left end to its right end to the end position shown in the right illustration of  FIG.  7   , in which the rotational movement of the outer bearing ring  3  relative to the inner bearing ring is stopped at a total angle of rotation of 400° or in a 1 o&#39;clock position, respectively. 
     LIST OF REFERENCE SYMBOLS 
       1  Rolling element bearing 
       2  Inner bearing ring 
       3  Outer bearing ring 
       4  Rolling elements 
       5  Inner raceway on  2   
       6  Inner raceway on  2   
       7  Outer raceway on  3   
       8  Outer raceway on  3   
       9  Angle-of-rotation limiting device 
       10  First stop element 
       11  Second stop element 
       12  Outer lateral surface of  2   
       13  Radial base bores 
       13   a  First radial base bore 
       13   b  Last radial base bore 
       14  Radial base groove 
       15  Angle limiter 
       16  Inner lateral surface of  3   
       17  Pivoting finger