Patent Publication Number: US-2003223667-A1

Title: Off-axis loaded bearing

Description:
BACKGROUND  
       [0001] A roller bearing may be used in various applications to reduce the friction between a fixed and a moving surface. Bearings may also be designed to accommodate various loads.  
       SUMMARY OF THE INVENTION  
       [0002] An embodiment of the present invention is directed to a roller bearing having a central axis comprising an inner race having a first race track; an outer race disposed concentrically around the inner race with respect to the central axis and having a second race track facing the first race track; and a plurality of rolling bodies disposed between the inner race and the outer race for rolling against the first race track and the second race track. Each of the plurality of rolling bodies has a fixed axis of rotation about which each of the rolling bodies rotates, each of the rolling bodies being rotatably attached to the roller bearing such that the fixed axis of rotation about which each of the rolling bodies rotates remains substantially parallel to the central axis of the roller bearing. 
     
    
    
     DESCRIPTION OF THE FIGURES  
     [0003] For the present invention to be understood clearly and readily practiced, the present invention will be described in conjunction with the following figures, wherein:  
     [0004]FIG. 1 is a schematic plane view of a bearing according to an embodiment of the present invention;  
     [0005]FIG. 2 is a sectional view along sectional line A-A according to the embodiment illustrated in FIG. 1;  
     [0006]FIG. 3 is a cross-sectional view of the bearing illustrated in FIG. 1;  
     [0007]FIG. 4 is an exploded view of a bearing of the bearing illustrated in FIG. 1;  
     [0008]FIG. 5 is a three-dimensional perspective view of the bearing illustrated in FIG. 1;  
     [0009]FIGS. 6 through 9 illustrate an exemplary method for assembling a bearing according to an embodiment of the present invention;  
     [0010]FIG. 10 is a schematic plane view of a bearing according to an embodiment of the present invention;  
     [0011]FIG. 11 is a sectional view along sectional line B-B of the bearing illustrated in FIG. 10;  
     [0012]FIG. 12 is a three-dimensional cut view along sectional line B-B of the bearing illustrated in FIG. 10;  
     [0013]FIG. 13 is a schematic plane view of a bearing according to an embodiment of the present invention;  
     [0014]FIG. 14 is a cross-sectional view along section line C-C of the bearing illustrated in FIG. 13.  
     [0015]FIG. 15 is a schematic plane view of a bearing according to an embodiment of the present invention;  
     [0016]FIG. 16 illustrates a variety of exemplary roller shapes suitable for practicing the present invention;  
     [0017]FIG. 17 is a cross sectional view of a bearing according to an embodiment of the present invention;  
     [0018]FIG. 18 is an exploded view of the bearing illustrated in FIG. 17;  
     [0019]FIG. 19 is a three-dimensional cut view of the bearing illustrated in FIG. 17;  
     [0020]FIG. 20 is a cross sectional view of a bearing according to another embodiment of the present invention;  
     [0021]FIG. 21 is an exploded view of the bearing illustrated in FIG. 20;  
     [0022]FIG. 22 is a three-dimensional cut view of the bearing illustrated in FIG. 20. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0023] The present invention relates to a bearing having a plurality of rolling bodies disposed between an inner ring (or race) and an outer ring (or race). Each of the rolling bodies has an axis of rotation, and the races have a central axis of rotation. The bearing of the present invention resists binding between the rolling bodies and the races by maintaining the axes of rotation of the rolling bodies parallel to the central axis of the inner and outer races and by remaining free to roll on the race track. Traditional bearing cages, when subject to certain loads, impinge the rolling bodies, causing the bearing to have increased friction and to possibly jam The bearing of the present invention resists this sliding and/or jamming not only when subject to radial, axial, or centrifugal loads (or combinations thereof) but also forces generated at an axis of rotation external to the bearing.  
     [0024] For a general understanding of the features of the present invention, reference is made to the drawings, wherein like reference numerals have been used throughout to identify similar elements. Where reference numerals identify a collection of like elements, a lower case letter designation used in combination with the reference number identifies individual elements of the collection. The lower case letter designations are assigned to elements alphabetically in a counterclockwise fashion and, in the case of a collection of elements arranged linearly, the alphabetical designations proceed from top to bottom.  
     [0025]FIG. 1 is a schematic plane view of a bearing  5  according to an embodiment of the present invention. As shown in FIG. 1, bearing  5  includes an inner race  10 , an outer race  20 , a plurality of bored rollers commonly designated as  30 , a plurality of pins commonly designated as  40 , and two retaining disks  50  (one shown). The components of bearing  5  may be made from any sufficiently hard and durable material, such as steel. Inner race  10  is arranged substantially concentric and coplanar with outer race  20 . Inner race  10  and outer race  20  have a common central axis  15 . Bored rollers  30  may be disposed in a space between races  10  and  20  at substantially equal intervals, as shown in FIG. 1, and are configured to roll against races  10  and  20 . So arranged, bored rollers  30  have centers at a common radius measured from central axis  15  of concentric races  10  and  20 . According to an embodiment, pins  40  may be inserted through bored rollers  30  so that rollers  30  may rotate independently of pins  40 . Retaining disks  50  may then be used to secure pins  40  from moving in the longitudinal direction while allowing pins  40  to rotate independently of retaining disk  50 .  
     [0026]FIG. 2 is a sectional view of bearing  5  along sectional line A-A. As shown in FIG. 2, bearing  5  includes roller  30   a  disposed between races  10  and  20 , pin  40   a , a top retaining disk  50   a  and a bottom retaining disk  50   b  (collectively, “retaining disks  50 ”), a top shield  60   a  and a bottom shield  60   b  (collectively, “shields  60 ”), and a top groove  210   a  and a bottom groove  210   b  (collectively, “grooves  210 ”). The inwardly facing surface of outer race  20  is provided with a race track  22  while the outwardly facing surface of inner race  10  is also provided with a race track  12 .  
     [0027] As described in connection with FIG. 1, retaining disks  50  restrict longitudinal movement of pins  40  in a manner that permits rollers  30  to rotate independent of retaining disks  50 . According to the embodiment illustrated in FIG. 2, retaining disks  50  secure pins  40  by a snap fit. Those of ordinary skill in the art will appreciate, however, that other permanent or releasable fastening mechanisms may be used.  
     [0028] Shields  60  may be positioned between inner and outer races  10  and  20  and axially outside race tracks  12  and  22  to maintain lubricants and exclude foreign material with respect to the gearing. Shields  60  may be disposed at both axial ends of race tracks  12  and  22 , and do not interfere with the rotation of the inner race. In the embodiment shown, shields  60  are fixedly attached in annular grooves  210  provided in outer race  20 . According to an embodiment, each shield  60  may have a flexible inner edge that is adapted to slidingly contact inner race  10  along an arcuate recess provided along the outer periphery of inner race  10  at the axial ends. According to another embodiment, shields  60  may be fixedly attached in annular grooves provided in inner race  10 .  
     [0029]FIG. 3 is a cross-sectional view of bearing  5 . Bearing  5  includes roller  30   a  disposed between races  10  and  20 , pin  40   a , top and bottom retaining disks  50   a  and  50   b , top and bottom shields  60   a  and  60   b , a top notch  310   a  and a bottom notch  310   b  (collectively, “notches  310 ”) in pin  40   a , a top rim  320   a , and a bottom rim  320   b  (collectively, “rims  320 ”) on inner race  10 . Notches  310 , in combination with pin  40   a , are adapted to receive retaining disks  50  using, for example, a conventional snap-fit fastening technique. According to such an embodiment, notches  310  are adapted to allow pins  40  to rotate independent of retaining disks  50 .  
     [0030] Rims  320  of bearing  5  provide retaining means to prevent pins  40  and retaining disks  50  from moving axially and interfering with the operation of rollers  30 . More specifically, inner race  10  includes top and bottom rims  320   a  and  320   b  so that if, for example, retaining disk  50   b  were to move upward in the axial direction, disk  50   a  would be limited by rim  320   b . According to another embodiment, rims may additionally or alternatively extend from outer race  20 .  
     [0031]FIGS. 4 and 5 illustrate various views of bearing  5 . FIG. 4 is an exploded view of a bearing  5 . FIG. 4 illustrates the components of bearing  5  including inner race  10 , outer race  20 , bored rollers  30 , pins  40 , retaining disks  50 , and shields  60 . Once assembled, retaining disks  50  and shields  60  engage inner and outer races  10  and  20 . FIG. 5 is a three-dimensional view of bearing  5  with a section cut out to illustrate the inner assembly. To prevent binding of rollers  30 , races  10  and  20  should be fabricated to allow, for example, 0.001 inch between rollers  30  and races  10  and  20 .  
     [0032]FIGS. 6 through 9 illustrate an exemplary method for assembling a bearing according to an embodiment of the present invention. First, rollers  30  may be rotated to fill approximately one half of inner race  10  as illustrated in FIG. 7 Second, rollers  30  may then be moved around inner race  10 , as illustrated in FIG. 7, into approximately evenly spaced locations. Third, as shown in FIG. 8 retaining disk  50   b , with pins  40  attached, may be inserted into bearing  5  so that pins  40  slip through the bored shafts of rollers  30 . Finally, in the fourth step, retaining disk  50   a  is attached to the opposite end of pins  40  as shown in FIG. 9. Shields  60  may optionally be placed over retaining disks  50 .  
     [0033]FIG. 10 is a schematic plane view of a bearing  500  according to an embodiment of the present invention. Bearing  500  includes an inner race  510 , an outer race  520 , a plurality of rollers commonly designated as  530 , a plurality of outer spacer rollers commonly designated  540 , a plurality of inner spacer rollers commonly designated  550 , and a plurality of retaining clips commonly designated  560 . According to such an embodiment, rollers  530  are disposed between inner race  510  and outer race  520  and spaced approximately equal distances apart. Outer spacer roller  540   a  is positioned tangentially to adjacent rollers  530   a  and  530   b  but does not touch outer race  520 . Inner space roller  550   a  is also positioned tangentially to adjacent rollers  530   a  and  530   b  but closer to inner race  510  without touching it. Retaining clip  560   a  is not fixedly attached to spacer rollers  540   a  and  550   a , but instead allows spacer rollers  540   a  and  550   a  to rotate about their respective axes.  
     [0034] When inner race  510  rotates, such as by contact with a shaft, rollers  530  begin to roll against outer race  520 . Spacer rollers  540  and  550  further limit radial movement of rollers  530  as they rotate around inner race  510 . Additionally, where spacer rollers  540  and  550  contact rollers  530 , the rotation of rollers  530  causes spacer rollers  540  and  550  also to rotate.  
     [0035]FIG. 11 is a sectional view of bearing  500  along sectional line B-B. As shown, bearing  500  includes inner and outer races  510  and  520 , roller  530   d , outer spacer roller  540   a , inner spacer roller  550   a , retaining clip  560   a , a top inner rim  570   a , a bottom inner rim  570   b , a top outer rim  580   a , and a bottom outer rim  580   b . Inner race  510  includes top and bottom inner rims  570  that limit axial movement of rollers  530  and retaining clips  560 . FIG. 12 is a three-dimensional cut view of bearing  500  along sectional line B-B of FIG. 10.  
     [0036]FIG. 13 is a schematic plane view of a bearing  700  according to an embodiment of the present invention. This embodiment is similar to that shown in FIGS. 10 through 12 except that retaining clips  560  have been combined to form a retaining disk  710  that holds spacer rollers  540  and  550 . FIG. 14 is a cross-sectional view of bearing  700  along section line C-C of FIG. 13 that illustrates retaining disk  710 .  
     [0037]FIG. 15 is a schematic plane view of a bearing  800  according to an embodiment of the present invention. This embodiment is similar to that shown in FIGS. 13 and 14 except that every other inner spacer roller  550  and every other outer spacer roller  540  is removed. Retaining disk  710  holds spacer rollers  540  and  550  apart and within inner race  10  and outer race  20 .  
     [0038]FIG. 16 illustrates a variety of exemplary roller shapes suitable for practicing the present invention, including elliptical, cylindrical, spindle, and barrel shapes. Those of ordinary skill in the art will appreciate, however, that any complementary shape symmetric with respect to an axis of rotation may be suitable. The barrel design is preferred because it is self-centering, i.e., its axis of rotation stops parallel to the axes of the inner and outer races, forcing the components to maintain a state of levelness during operation. Those of ordinary skill in the art will also appreciate that the rollers may be solid as illustrated in FIGS. 11 through 14 or, preferably, bored as illustrated in FIG. 1. According to another embodiment, the pins and roller can be combined into a unitary structure as illustrated in FIGS. 11 through 14, although the pins and rollers cannot rotate independently.  
     [0039]FIG. 17 is a cross sectional view of a bearing  900  according to an embodiment of the present invention. Bearing  900  includes an inner race  910 , an outer race  20 , a roller  920   a , pin  40   a , top and bottom shields  60 , a top magnetic disk  920   a , a bottom magnetic disk  920   b  (collectively, “magnetic disks  920 ”), and a top circular magnetic washer  930   a  and a bottom circular magnetic washer  930   b  (collectively, “magnetic washers  930 ”) on roller  920   a . Bearing  900  is similar to bearing  500  shown in FIG. 1 except that retaining disks  50  and rims  320  of bearing  500  have been replaced by a plurality of magnetic disks and washers. The polarities of magnetic disks  920  and magnetic washers  930  are arranged to repel each other to further limit axial displacement of pins  40  during operation of bearing  900 .  
     [0040]FIG. 18 is an exploded view of bearing  900  that shows, like FIG. 17, magnetic washers  930  inserted into roller  920   a . Those of ordinary skill in the art will appreciate, however, that magnetic washers  930  may be attached to the top, partially sunk into the end of rollers  920  or completely sunk so that a surface of magnetic washers  930  are flush with a top surface of rollers  920 . FIG. 19 is a three-dimensional cut view of bearing  900 .  
     [0041]FIG. 20 is a cross sectional view of a bearing  950  according to another embodiment of the present invention. Bearing  950  includes inner race  910 , outer race  20 , roller  920   a , pin  40   a , shields  60 , a top magnetic washer  960   a  mounted to a top retaining disk  970   a , and a bottom magnetic washer  960   b  mounted to a bottom retaining disk  970   b . Bearing  950  is similar to bearing  900  except that retaining disks  970  have magnetic washers  960  mounted into them, rather than full magnetic disk of bearing  900 . Washers  960  may be partially sunk into retaining disks  970  or completely sunk such that the surface of, for example, magnetic washer  960   a  is flush with the roller-side surface of retaining disk  970   a.    
     [0042]FIG. 21 is an exploded view of bearing  950  that illustrates the manner in which magnetic washers  930  may be inserted into roller  920   a . FIG. 21 also illustrates the manner in which magnetic washers  960  may be mounted on retaining disks  970 . FIG. 22 is a three-dimensional cut view of bearing  900 .  
     [0043] It can thus be appreciated that while the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the scope and spirit of the invention.