Patent Publication Number: US-2022235821-A1

Title: Cage segment and associated rolling bearing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to French Patent Application no. 2100735, filed Jan. 27, 2021, the contents of which is fully incorporated herein by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to rolling bearings. 
     The present invention relates more particularly to a cage segment for a rolling bearing, and a rolling bearing comprising segmented cages each comprising a plurality of segments. 
     STATE OF THE ART 
     For applications which require axially and radially significant load absorption, it is known practice to use a first type of rolling bearing with three rows of rollers comprising two rows of axial rollers and one row of radial rollers. 
     However, the bulk of such a rolling bearing requires significant installation space. 
     For applications in which the load absorptions are lower, it is possible to use a second type of rolling bearing with crossed rollers which have a reduced bulk. 
     To ensure that the circumferential spacing of these types of rolling bearing is maintained, it is known practice to use a segmented cage which consists of a plurality of successive cage segments in the circumferential direction. Such cage segments are generally made of a synthetic material. 
     Under the effect of the centrifugal force or when the relative speed of rotation of the inner and outer rings is low, the cage segments can rub on these rings and be damaged. The cage segments can also jam between the raceways of the rings. 
     It is therefore proposed to wholly or partly mitigate these drawbacks. 
     SUMMARY OF THE INVENTION 
     In light of the above, the invention proposes a cage segment for a rolling bearing delimiting a plurality of through pockets for receiving rollers and comprising first and second walls extending in the circumferential direction and provided with internal surfaces opposite one another and forming abutment surfaces for the end faces of the rollers, and a plurality of beams extending transversely between the first and second walls and linking the walls, each pocket being delimited in the circumferential direction by two successive beams and each beam partly delimiting two successive pockets. 
     Each beam comprises, at a lateral end, a protuberance of concave outer form and intended to come into contact with the outer surface of at least one roller, two protuberances being opposite in the circumferential direction for each through pocket. 
     The protuberances keep the cage segment centred on the rollers such that, at high rolling rotation speed, when the centrifugal force throws the cage segment, the cage segment is kept centred by the rollers between the raceways, reducing the risk of the cage segment rubbing on the revolving ring. 
     According to a feature, each beam comprises two protuberances of concave outer form. 
     Advantageously, for each beam, one of the protuberances extends circumferentially on the side of one of the pockets delimited by the beam and the other protuberance extends circumferentially on the side of the other pocket delimited by the beam. 
     Preferably, each protuberance of a beam is opposite, in the circumferential direction, a protuberance of the successive beam. 
     According to another feature, the protuberances of each beam are disposed on the opposite lateral ends of the beam. 
     Preferably, the protuberances of the beams are identical. 
     Advantageously, each concave protuberance has a circular form when considering an axial cross section of the cage segment. 
     Preferably, the radius of curvature of each protuberance is greater by 1.5% to 2.5%, and preferably greater by 2%, than the radius of the rollers. 
     In one embodiment, the cage segment comprises a central portion extending in the circumferential direction, the central portion comprising the beams, the first and second walls, the cage segment further comprising a first lateral shoulder outwardly extending the first wall of the central portion, and a second lateral shoulder outwardly extending the second wall of the central portion by being oriented at right angles to the first lateral shoulder. 
     In a particular embodiment, at least one outwardly open recess is formed on each of the first and second lateral shoulders. 
     The recesses make it possible to reduce the friction surface of the cage segments on the inner and outer rings of the associated rolling bearing. The recesses can form reservoirs of lubricant allowing the rollers to be lubricated. The lubricant can for example be grease or oil. 
     According to a feature, at least one recess is formed on a guiding surface of the first lateral shoulder which links a free end surface of the shoulder to the central portion. 
     Advantageously, the cage segment comprises at least one recess formed on a free end surface of the first lateral shoulder. 
     Preferably, the cage segment comprises at least one recess formed on a guiding surface of the second lateral shoulder which links a free end surface of the shoulder to the central portion. 
     Preferably, the cage segment comprises at least one recess formed on a free end surface of the second lateral shoulder. 
     In another particular embodiment, the cage segment can be without one or more such recesses. 
     Advantageously, the axial length of the second shoulder is greater than the radial length of the first shoulder. 
     Also proposed is a segmented cage for a rolling bearing comprising a plurality of cage segments as defined previously. 
     Also proposed is a rolling bearing comprising an inner ring, an outer ring, at least one row of rollers disposed between raceways of the rings, and at least one segmented cage as defined previously for maintaining the circumferential spacing of the rollers of the row. 
     According to a feature, the rolling bearing comprises at least two rows of rollers, and at least two segmented cages for holding rows of rollers, the second shoulders of the cage segments of one of the cages being axially opposite the second shoulders of the cage segments of the other cage. 
     Preferably, the first shoulders of the cage segments of the cages extend radially and the second shoulders of the cage segments of the cages extend axially. 
     Advantageously, a first row of rollers forms an angle of orientation with the axis of rotation of the rolling bearing, and the axis of rotation of a second row of rollers forms the angle of orientation of opposite sign with the axis of rotation of the rolling bearing. 
     Preferably, the angle is equal to 45°. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Other aims, features and advantages of the invention will become apparent on reading the following description, given purely as a nonlimiting example, and with reference to the attached drawings in which: 
         FIG. 1  is a partial cross-sectional view of a rolling bearing according to an exemplary embodiment of the invention; 
         FIG. 2  is a perspective view of a cage segment of the rolling bearing of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the cage segment of  FIG. 2  inside which a roller is housed; 
         FIGS. 4-6  are perspective views from three other different viewing angles of the cage segment of the rolling bearing of  FIG. 1 ; and 
         FIG. 7  is a detail view of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is made to  FIG. 1  which illustrates an example of a rolling bearing  1  comprising an outer ring  2  and an inner ring  3  which are concentric. The outer  2  and inner  3  rings extend axially along the axis of rotation (not represented) of the rolling bearing. 
     The inner ring  3  is formed by two half-rings  4 ,  5  stacked axially. 
     The outer ring  2  comprises two attached raceways  6 ,  7 . The inner ring  3  also comprises attached raceways  8 ,  9 . 
     The raceways  6 ,  7 ,  8 ,  9  are mounted freely in the outer  2  and inner  3  rings. The raceways  7  to  9  can thus be oriented angularly to compensate for an offset of the inner  3  and outer  2  rings. 
     The rolling bearing  1  further comprises two rows of rollers  10 ,  11  disposed respectively between the raceways  6 ,  8  and  7 ,  9  of the rings  2 ,  3 . Each roller  10 ,  11  comprises an outer rolling surface. Each roller  10 ,  11  comprises two end faces which delimit its outer rolling surface. The axis of rotation of each roller  10  is at right angles to the axis of rotation of each roller  11 . 
     The rolling bearing  1  also comprises two segmented cages  12 ,  13  for maintaining, respectively, the circumferential spacing of the rows of rollers  10 ,  11 . 
     Each segmented cage  12 ,  13  comprises a plurality of successive identical cage segments  14 ,  15  in the circumferential direction and that come into contact against one another. 
     Since the cage segments  14 ,  15  are identical to one another, only one of the cage segments  14  will be detailed hereinbelow. 
       FIG. 2  illustrates a perspective view from a first angle of a cage segment  14 . 
     The cage segment  14  comprises a central portion  16  extending in the circumferential direction and delimiting a plurality of through pockets  18  for receiving the rollers  10 . 
     The central portion  16  comprises first and second walls  49 ,  51  extending in the circumferential direction and provided with internal surfaces  20 ,  22  opposite one another. As will be described in more detail hereinbelow, the cage segment  14  also comprises a plurality of beams extending transversely between the first and second walls  49 ,  51  to delimit the pockets  18  of the rollers. 
     The first and second walls  49 ,  51  form abutment surfaces for the end faces of the rollers  10 ,  11 . 
     The cage segment  14  further comprises a first lateral shoulder  24  outwardly extending the first wall  49  of the central portion  16  and a second lateral shoulder  26  outwardly extending the second wall  51  of the central portion  16  by being oriented at right angles to the first lateral shoulder  24 . 
     The first and second shoulders  24 ,  26  comprise a plurality of recesses as will be detailed in greater detail hereinbelow. 
     As a variant, the cage segment  14  does not comprise the first and second lateral shoulders  24 ,  26 . 
       FIG. 3  is a cross-sectional view of the central portion  16  of the cage segment  14 . In the interests of clarity, a single roller  10  is represented in one of the pockets. Obviously, each pocket  18  houses one roller. 
     As indicated previously, the cage segment  14  comprises a plurality of beams  52   a,    52   b,    52   c,    52   d,    52   e,    52   f  extending transversely between the first and second walls  49 ,  51  ( FIG. 2 ) and linking the walls. The beams  52   a  to  52   f  are spaced apart from one another in the circumferential direction. Each pocket  18  is delimited in the circumferential direction by two successive beams  52   a  and  52   b,    52   b  and  52   c,    52   c  and  52   d,    52   d  and  52   e,    52   e  and  52   f.  Each beam  52   b,    52   c,    52   d,    52   e  partly delimits two successive pockets  18  apart from the beams  52   a  and  52   f  situated at the ends of the cage segment  14  which each partly delimit a single pocket  18   a,    18   e.    
     Since the beams  52   b,    52   c,    52   d,    52   e  are of identical design, and the end beams  52   a  and  52   f  are of identical design, only the beams  52   c  and  52   d  and the end beam  52   a  are detailed. 
     The beams  52   a,    52   c,    52   d  comprise, at a lateral end  54   a,    54   b,    54   c,  a first protuberance  56   a,    56   b,    56   c  of concave outer form and intended to come into contact with the outer surface of the roller  10 . The protuberances  56   b,    56   c  of two successive beams are opposite in the circumferential direction for each through pocket  18 . 
     The protuberances  56   a,    56   b,    56   c  keep the cage segment  14  centred on the rollers  10  so that, at high relative rolling speed of the outer ring  2  with respect to the inner ring  3 , when the centrifugal force throws the cage segment  14  towards the inner ring  3 , the cage segment  14  is kept centred by the rollers  10  between the raceways  6 ,  8  reducing the risk of friction of the cage segment  14  on the inner ring  3 . 
     The beams  52   c  and  52   d  comprise a second protuberance  58   c,    58   d  of concave outer form disposed on the lateral ends  60   c,    60   d  opposite the lateral ends  54   b,    54   c.    
     The alternate disposition of the positioning of the protuberances  56   b,    56   c,    58   c,    58   d  on one of the ends  54   b,    54   c,    60   c,    60   d  of the beams  52   c,    52   d  delimiting the pockets  18   b,    18   c,    18   d  makes it possible to simplify the mounting of the segment  14  in the rolling bearing  1  and to centre the cage segment  14  on the rollers  10  so that, when the relative rolling speed of the outer ring  2  with respect to the inner ring  3  is not great enough to neutralize the gravity driving the cage segment  14  under the effect of its weight towards the outer ring  2 , the cage segment  14  is kept centred by the rollers  10  between the raceways  6 ,  8 , reducing the risk of friction of the cage segment  14  on the outer ring  2 . 
     The protuberances  56   b,    56   c  extend circumferentially on the side of the pocket  18  delimited by the beams and the protuberances  58   c,    58   d  extend circumferentially on the side of the other pockets  18  delimited by the beams. 
     The protuberance  56   b  of the beam  52   c  is opposite, in the circumferential direction, the protuberance  56   c  of the successive beam  52   d.    
     As a variant, the second protuberances of concave outer form  58   c,    58   d  can be disposed on the lateral ends  54   b,    54   c,  the second protuberances of concave outer form  58   c,    58   d  extending circumferentially on the side of the pockets  18   b,    18   d  delimited respectively by the beams. 
     The protuberances  56   a,    56   b,    56   c,    58   c,    58   d  are identical. 
     As a variant, the protuberances  56   a,    56   b,    56   c,    58   c,    58   d  can be different. 
     As illustrated, the concave protuberances  56   a,    56   b,    56   c,    58   c,    58   d  have a circular form when considering an axial cross section of the cage segment. 
     Obviously, the concave protuberances  56   a,    56   b,    56   c,    58   c,    58   d  can have a different form. 
     According to one embodiment, the radius of curvature of each protuberance  56   a,    56   b,    56   c,    58   c,    58   d  is greater by 1.5% to 2.5%, and preferably greater by 2%, than the radius of the rollers  10 . 
     Each pocket  18  comprising such a radius of curvature moulds to the roller  10  over a greater surface of the roller  10  so as to hold the roller  10  and such that the rollers  10  keep the cage segment  14  centred on the rollers  10 . 
     Obviously, the pockets  18  can have a different configuration, notably without concave protuberances  56   a,    56   b,    56   c,    58   c,    58   d  or with concave protuberances produced from segments to approximate a circular form when considering an axial cross section of the cage segment. 
     Referring once again to  FIG. 2 , as indicated previously, the second lateral shoulder  26  comprises a guiding surface  28  linking a free end surface  32  of the shoulder to the central portion  16 . As can be seen in  FIG. 1 , the guiding surface  28  is intended to come radially opposite the inner ring  3 . The free end surface  32  is intended to come axially opposite the inner ring  3  of the corresponding free end surface of the cage segment  13 . 
     Referring to  FIGS. 2 and 4 to 6 , a recess  30  is formed on the guiding surface  28 . The bottom of the recess  30  is offset towards the inside of the cage segment with respect to the guiding surface  28 . The recess  30  is oriented towards the outside of the cage segment. In the exemplary embodiment illustrated, a single recess  30  is formed on the guiding surface  28 , and centred on the guiding surface  28 . The bottom of the recess  30  is linked on either side to the guiding surface  28  by tapered surfaces (not referenced). As a variant, it could be possible to provide at least two recesses on the guiding surface  28  spaced apart in the circumferential direction. In the exemplary embodiment illustrated, the recess  30  extends over the entire width of the guiding surface  28 . Alternatively, the recess  30  could have a reduced dimension. 
     As can be seen in  FIG. 4 , a recess  34  is formed on the free end surface  32 , and centred on the free end surface  32 . The bottom of the recess  34  is offset towards the inside of the cage segment with respect to the free end surface  32 . 
     The recess  34  is oriented towards the outside of the cage segment. In the exemplary embodiment illustrated, a single recess  34  is formed on the free end surface  32 . The bottom of the recess  34  is linked on either side to the free end surface  32  by tapered surfaces (not referenced). As a variant, it could be possible to provide at least two recesses on the free end surface  32  spaced apart in the circumferential direction. In the exemplary embodiment illustrated, the recess  34  extends over the entire width of the free end surface  32 . Alternatively, the recess  34  could have a reduced dimension. 
     The first lateral shoulder  24  comprises a guiding surface  36  linking a free end surface  40  of the shoulder to the central portion  16 . As can be seen in  FIG. 1 , the guiding surface  36  is intended to come axially opposite the inner ring  3 . The free end surface  40  is intended to come radially opposite the outer ring  2 . 
     Referring once again to  FIGS. 5 and 6 , a recess  38  is formed on the guiding surface  36 , and centred on the guiding surface  36 . The bottom of the recess  38  is offset towards the inside of the cage segment with respect to the guiding surface  36 . The recess  38  is oriented towards the outside of the cage segment. In the exemplary embodiment illustrated, a single recess  38  is formed on the guiding surface  36 . The bottom of the recess  38  is linked on either side to the guiding surface  36  by tapered surfaces (not referenced). As a variant, it could be possible to provide at least two recesses on the guiding surface  36  spaced apart in the circumferential direction. In the exemplary embodiment illustrated, the recess  38  extends over the entire width of the guiding surface  36 . Alternatively, the recess  38  could have a reduced dimension. 
     As can be seen in  FIG. 6 , a recess  42  is formed on the free end surface  40 . The bottom of the recess  42  is offset towards the inside of the cage segment with respect to the free end surface  40 , and centred on the free end surface  40 . The recess  42  is oriented towards the outside of the cage segment. In the exemplary embodiment illustrated, a single recess  42  is formed on the free end surface  40 . The bottom of the recess  42  is linked on either side to the free end surface  40  by tapered surfaces (not referenced). As a variant, it could be possible to provide at least two recesses on the free end surface  40  spaced apart in the circumferential direction. In the exemplary embodiment illustrated, the recess  42  extends over the entire width of the free end surface  40 . Alternatively, the recess  42  could have a reduced dimension. 
     The recess  42  extends the recess  38 , and the recess  34  extends the recess  30 . 
       FIG. 7  illustrates the rolling bearing  1  without the inner and outer rings  2 ,  3 . 
     The second shoulders  26  of the cage segments  14  of the segmented cage  12  are axially opposite the second shoulders  26  of the cage segments  15  of the segmented cage  15 . 
     The second shoulders  26  of the cage segments  14 ,  15  of cages  12 ,  13  extend axially and the first shoulders  24  of the cage segments  14 ,  15  of the cages extend radially. 
     The radial length L 24  of the first shoulder  24  is less than the radial length L 26  of the second shoulder  26 . 
     The axis of rotation X 10  of a first row of rollers  10  forms an angle of orientation al with the axis of rotation A 1  of the rolling bearing  1 , and the axis of rotation X 11  of a second row of rollers  11  forms the angle of orientation al of opposite sign α 2  with the axis of rotation A 1  of the rolling bearing  1 . The opposing orientation of the axes of rotation X 10 , X 11  of the first and second rows of rollers  10 ,  11  with respect to the axis of rotation A 1  of the rolling bearing allows the rolling bearing  1  to support higher axial and radial loads than a rolling bearing with crossed rollers according to the state of the art. 
     For example, the angle al formed by the axes X 10  and A 1  is equal to 45° and the angle α 2  formed by the axes X 11  and A 1  is equal to −45° such that the rolling bearing  1  supports axial and radial loads of the same maximum value. 
     As a variant, the values of the angles α 1  and α 2  can be different values. 
     The recesses  30 ,  38 ,  42  of the guiding surfaces  28 ,  36 ,  40  make it possible to reduce the friction surface of the cage segments  13 ,  14  on the inner and outer rings. 
     The recess  34  of the free end surface  32  makes it possible to limit the friction and the deterioration of the cage segments  13 ,  14  when they enter into contact. 
     Furthermore, the recesses  30 ,  38  form lubricant reservoirs allowing the rollers  10 ,  11  to be lubricated. 
     As a variant, the cage segment  14 ,  15  does not comprise recesses  30 ,  34 ,  38 ,  42 .