Title of Invention: Spacer for rolling bearing, notably used in a wind turbine
Abstract: A spacer for a rolling bearing, most notably for use in a wind turbine is provided. The spacer is adapted for a rolling bearing having an inner ring, an outer ring and at least one row of angular contact rollers disposed between raceways provided on the rings. The spacer includes two opposite faces 17, 18 having a concave profile adapted to the rollers, each face comprising at least a contact surface 17a, 18a with the associated roller having the shape of a cylinder segment. The axes of the cylinder segments of the contact surfaces converge.
Detailed Description: Part general_description_paragraphs: Part CROSS-REFERENCE: This application is the U.S. national stage of International Application No. PCT/EP2011/065183 filed on Sep. 2, 2011.
Part TECHNICAL FIELD: The present invention relates to the field of rolling bearings, in particular rolling bearings having an inner ring and an outer ring with one or more rows of contact rollers therebetween.
The invention relates more particularly to the field of large-diameter rolling bearings adapted to be used in a wind turbine.
Part RELATED ART: In such application, rolling bearings are used to angularly orient the rotor of the turbine according to the direction of the wind, and to orient the blades of the turbine around their longitudinal axes. Such rolling bearings are loaded mainly by stress, both axially and radially, often with a relatively strong load.
A rolling bearing for a wind turbine comprises two concentric inner and outer rings, at least a row of oblique contact rollers arranged between raceways and guiding faces provided on said rings, and a plurality of spacers disposed circumferentially between the rollers. Each spacer generally comprises two opposite cavities having a concave profile adapted to the rollers and delimited axially by lateral flanges.
Under the action of the loads to which a rolling bearing is subjected during operation of the wind turbine, the rollers of a row may slightly skew or tilt with respect to the raceways of the inner and outer rings. Accordingly, the service life of the rolling bearing reduces.
One aim of the present invention is to overcome this drawback.
Part SUMMARY: It is a particular object of the present invention to provide a spacer for rolling bearing adapted to reduce the skewing of the rollers.
In one embodiment, the spacer for rolling bearing comprising an inner ring, an outer ring and at least one row of angular contact rollers disposed between raceways provided on the rings, comprises two opposite faces having a concave profile adapted to the rollers. The spacer comprises two opposite faces having a concave profile adapted to the rollers. Each face comprises at least a contact surface with the associated roller having the shape of a cylinder segment, the axes of the cylinder segments of said contact surfaces converging.
The spacer may comprise opposite lateral flanges delimiting axially the opposite faces, the thickness of the spacer between the opposite faces decreases from one of the lateral flange to the other lateral flange.
In one embodiment, the minimum thickness tmin and the maximum thickness tmax of the spacer are defined by:




  1
  ,
  
    05
    ≤
    
      
        t
        
          ma
          ⁢
          
            
          
          ⁢
          x
        
      
      
        t
        
          m
          ⁢
          
            
          
          ⁢
          i
          ⁢
          
            
          
          ⁢
          n
        
      
    
    ≤
    4
  




The minimum thickness may be equal to or greater than 5 mm.
The minimum thickness tmin may be equal to or greater than 5% of the diameter of the associated roller.
In one embodiment, each face comprises two contact surfaces with the associated roller and a concave recess extending between said contact surfaces and directed outwards towards said roller, the cylinder segments of each face being coaxial.
The spacer may further comprises opposite inner and outer parts adapted to come into contact with the raceways of the rings, the recess extending between said inner and outer parts. Advantageously, the recess extends from the inner part to the outer part.
In one embodiment, the inner and outer parts each comprise two contact surfaces and a concave recess disposed therebetween. The recess of the face may extend from the recess of the inner part to the recess of the outer part. Advantageously, the recesses of the inner and outer part extend from one face to the other.
The lateral flanges may each comprise one contact surface and a recess in a form of a groove formed onto said surface. Advantageously, the lateral flanges each further comprise additional recesses located on the both sides of the contact surface.
In one embodiment, the spacer further comprises a through-hole putting the faces into communication. Preferably, the through-hole opens onto the recess of the face.
In one embodiment, the spacer is formed in one part from metal or from polymer material.
In another aspect of the invention, a rolling bearing comprises an inner ring, an outer ring, at least one row of angular contact rollers disposed between raceways provided on the rings, and a plurality of identical spacers as previously defined and disposed circumferentially between the rollers.
In one embodiment, the number of contact rollers Zw of the row is defined by




  
    Z
    w
  
  =
  
    
      π
      ×
      
        d
        m
      
    
    
      
        d
        w
      
      +
      
        t
        med
      
    
  




and rounded to the lower integer value, with

dm corresponding to the bearing pitch diameter,
dw corresponding to the diameter of the rollers, and
tmed corresponding to the medium thickness of one spacer in a mid-plane containing the axes of the associated rollers.
In another embodiment, the number of contact rollers Zw is smaller than




  
    π
    ×
    
      d
      m
    
  
  
    
      d
      w
    
    +
    
      t
      med
    
  




rounded to the lower integer value.

In one embodiment, the angle α formed between the axes of the two rollers associated to one spacer is defined by




  α
  =
  
    
      360
      
        Z
        w
      
    
    .
  




The rolling bearing as previously defined may be particularly useful as a bearing for a wind turbine comprising a mast holding a nacelle where blades are installed, in particular for rotating the nacelle with respect to the mast and/or for rotating/pitching each blade around its longitudinal axis.
Part DETAILED DESCRIPTION OF THE INVENTION: The rolling bearing as illustrated on the FIGS. 1 and 2 is a large-diameter rolling bearing comprising an inner ring 1 and an outer ring 2 between which are housed two rows of oblique or angular contact rollers 3a and 3b. The rolling bearing also comprises a plurality of spacers 4 disposed circumferentially between the rollers 3a, 3b to maintain the circumferential spacing between them.
The inner and outer rings 1, 2 are concentric and extend axially along the bearing rotation axis (not shown) of the rolling bearing. The rings 1, 2 are of the solid type. A “solid ring” is to be understood as a ring obtained by machining with removal of material (by machining, grinding) from metal tube stock, bar stock, rough forgings and/or rolled blanks.
The rollers 3a, 3b are identical with one another and each comprise an exterior rolling surface and opposite end transverse faces delimiting axially the rolling surface. In the illustrated embodiment, the rolling surfaces have a cylindrical profile. Alternatively, the rolling surfaces may have a spherical profile or a logarithmic profile. For each row, the rotation axes 3′a, 3′b of the rollers converge in one single point located on the longitudinal axis of the bearing, and are disposed at a determined angle with respect to the bearing axis. In the illustrated embodiment, the rotation axes 3′a, 3′b of the rollers of the two rows are arranged at an angle of 90° to each other, and of approximately of 45° to the bearing axis. The angle between the rotation axis 3′a, 3′b of each roller and the bearing axis may be comprised for example between 20° and 70°.
The inner ring 1 has a bore 1a of cylindrical shape designed to be fixed to a chassis or to a structure of a machine (not shown) and delimited by opposite radial lateral surfaces 1b, 1c. The inner ring 1 also comprises a stepped exterior cylindrical surface 1d onto which first and second annular raceways 5, 6 are formed. The raceways 5, 6 are mutually symmetric with respect to a transverse radial plane passing through the centre of the rolling bearing. Each raceway 5, 6 extends obliquely inwards from the exterior cylindrical surface 1d and has a frustoconical shape. Each raceway 5, 6 has in cross section a straight internal profile in contact with the rolling surfaces of the rollers 3a, 3b. 
The outer ring 2 comprises an outer cylindrical surface 2a delimited by opposite radial lateral surfaces 2b, 2c. The outer ring 2 also comprises a stepped annular bore 2d of cylindrical shape into which first and second raceways 7, 8 are formed. The raceways 7, 8 are mutually symmetric with respect to the radial plane passing through the centre of the rolling bearing. The raceways 7, 8 are respectively parallel to the raceways 5, 6. Each raceway 7, 8 extends obliquely outwards from the bore 2d and has a frustoconical shape. Each raceway 7, 8 has in cross section a straight internal profile in contact with the rolling surfaces of the rollers 3a, 3b. The raceways 5, 6 of the inner ring and the raceways 7, 8 of the outer ring mutually face each other while at the same time being symmetric with regard to the rotation axis 3′a, 3′b of the rollers 3a, 3b. 
The inner ring 1 also comprises annular guiding faces 9, 10 formed onto the exterior surface 1d and which may be in axial contact with the end faces of the rollers with regard to the rotation axes 3′a, 3′b. The guiding faces 9, 10 are mutually symmetric with respect to the radial plane passing through the centre of rolling bearing. Each guiding face 9, 10 is straight and disposed perpendicular to the corresponding raceway 5, 6 and is connected to the edge of small diameter of said raceway by an annular concave fillet. Each guiding face 9, 10 extends obliquely outwards from said fillet and is connected to the exterior surface 1d of the inner ring. The guiding faces 9, 10 extend radially relative to the rotation axis 3′a, 3′b of the rollers. Each guiding faces 9, 10 and the associated raceway 5, 6 delimit a V-shaped groove directed radially outwards.
The outer ring 2 also comprises guiding faces 11, 12 formed into the bore 2d and which may be in axial contact with the opposite end faces of the rollers 3a, 3b with regard to the rotation axes 3′a, 3′b. The guiding faces 11, 12 are mutually symmetric with respect to the radial plane passing through the centre of rolling bearing. The guiding faces 11, 12 and the guiding faces 9, 10 mutually face each other and are respectively parallel. Each guiding face 11, 12 is straight and disposed perpendicular to the corresponding raceway 7, 8 and is connected to the edge of large diameter of said raceway by an annular concave fillet. Each guiding face 11, 12 extends obliquely inwards from said fillet and is connected to the bore 2d of the inner ring. Each guiding face 11, 12 extends radially relative to the rotation axis 3′a, 3′b of the rollers. Each guiding face 11, 12 and the associated raceway 7, 8 delimit a V-shaped groove directed radially inwards.
The raceway 5 and the guiding face 9 of the inner ring define together with the raceway 7 and the guiding face 11 of the outer ring a first annular space inside which the row of rollers 3a is disposed. Each roller 3a arranged between the raceways 5, 7 is maintained laterally in position by the guiding faces 9, 11 to avoid a skewing or tilting of said roller with respect to the raceways. Each guiding face 9, 11 form a flank having a direct contact surface with the associated end face of the rollers 3a to have a slight relative sliding between the end faces of rollers and the inner and outer rings 1, 2.
Similarly, the raceway 6 and the guiding face 10 of the inner ring define together with the raceway 8 and the guiding face 12 of the outer ring a second annular space inside which the row of rollers 3b is disposed. The arrangement of the rollers 3b with respect to the guiding faces 10, 12 is the same that the one previously described for the rollers 3a and the guiding faces 9, 11.
The spacers 4 are identical with one another and each placed between two consecutive rollers 3a, 3b of each row. The spacers 4 may be made in one part from metal, for instance from brass. Alternatively, the spacers 4 may be made from polymer material such as polyamide, for instance by molding.
As shown on FIGS. 2 to 4, each spacer 4 comprises two opposite inner and outer parts 13, 14 coming into contact with the facing raceways of the inner and outer rings 1 and 2, and two opposite lateral flanges 15, 16 coming into contact with the opposite guiding faces of said rings. Each spacer 4 also comprises two opposite faces 17, 18 adapted to receive two consecutive rollers. With regard to the rotation axes of said rollers, the faces 17, 18 are delimited axially by the lateral flanges 15, 16. The faces 17, 18 are delimited transversally by the inner and outer parts 13, 14.
As shown on FIG. 3, for the row of rollers 3a, the inner and outer parts 13, 14 of each spacer come into contact with the inner and outer raceways 5, 7 and the lateral flanges 15, 16 come into contact with the guiding faces 9, 11. The raceways 5, 7 and the guiding faces 9, 11 each form a flank having a direct contact surface with the associated part 13, 14 or flange 15, 16 to have a slight relative sliding between each spacer 4 and the rings 1, 2. In order to limit the induced friction torque of the spacers 4, a slight clearance is foreseen between each spacer and the raceways 5, 7 and the guiding faces 10, 12 of the rings. The arrangement of the spacers 4 for the row of rollers 3b with respect to the raceways 6, 8 and to the guiding faces 10, 12 of the rings is the same that the one described for row of rollers 3a. 
As shown on FIGS. 3 and 4, the outer part 14 of each spacer comprises two identical and separate planar contact surfaces 14a, 14b bearing against the associated raceway of the outer ring 2 and a concave recess 14c extending therebetween and which faces said raceway while remaining distant from the latter. In the illustrated embodiment, the recess 14c has in cross-section a U-shape. The recess 14c extends transversally from a longitudinal edge of the contact surface 14a to a facing longitudinal edge of the other contact surface 14b, and longitudinally from the face 17 to the other face 18.
With the concave recess 14c, the friction contacts between the outer part 14 of each spacer and the associated raceway of the outer ring 2 are reduced. Besides, the recess 14c advantageously acts as lubricant reservoir for lubricating the contact surfaces 14a, 14b of the outer part, the associated raceway of the outer ring 2 and the rolling surfaces of the rollers 3a and 3b, the lubricant emerging from the recess directly onto said contact and rolling surfaces and said raceway. The lubricant used (not shown) may be for example grease or oil.
Since the inner and outer parts 13, 14 of each spacer are identical in the illustrated embodiment, only one of them is described here, it being understood that the references “a, b, c” previously used for the outer part 14 are also used for the identical elements of the inner part 13. For the same reasons, only one of lateral flanges 15, 16 will be described, it being understood that the same references “a, b, c, d” are used for the identical elements of the two flanges.
The lateral flange 15 comprises a central planar contact surface 15a bearing against the associated guiding face of the inner ring, two identical concave recesses 15b, 15c which face said ring while remaining distant from the latter, and a groove 15d provided on the contact surface 15a. The distance separating the contact surfaces 15a and 16a of the two flanges 15, 16 is substantially equal to the length of the rollers 3a, 3b. 
The recess 15b extends from a first edge of the contact surface 15a to a longitudinal edge of the contact surface 14b of the outer part 14 which is opposite to the longitudinal edge of said surface connected to the recess 14c. The recess 15c extends from a second opposite edge of the contact surface 15a to a longitudinal edge of the contact surface 13b which is opposite to the longitudinal edge of said surface connected to the recess 13c. The recesses 15b, 15c extend longitudinally from the face 17 to the other face 18. The distance separating the two edges of the contact surface 15a is substantially equal to the length of the associated guiding face of the inner ring. The groove 15d is directed outwards and faces said guiding face while remaining distant from the latter. The groove 15d extends longitudinally from the face 17 to the other face 18 and has in cross-section a concave internal profile in the shape of a semi-circle.
As shown on FIG. 3, for the row of rollers 3a, the contact surface 15a of the lateral flange 15 comes into contact with the guiding face 9 of the inner ring 1, and the recess 15c faces the concave fillet which connects said guiding face and the raceway 5 while remaining distant from said fillet. The recess 15b is oriented towards the exterior surface 1d of the inner ring.
With the concave recess 15c and the concave groove 15d, the friction contacts between the lateral flange 15 and the inner ring 1 are reduced. Besides, the recesses 15b, 15c and the groove 15d advantageously act as lubricant reservoirs for lubricating the contact surface 15a, the guiding face 9 of the inner ring and the end faces of the rollers. The lubricant (not shown) emerges from the recesses 15b, 15c and the groove 15d directly onto the contact surface 15a, the guiding face 9 and the end faces of the rollers.
For the row of rollers 3a, the contact surface 16a of the lateral flange 16 bears against the guiding face 11 of the outer ring 2, and the recess 16b faces the concave fillet which connects said guiding face and the raceway 7 while remaining distant from said fillet. The recess 16c is oriented towards the bore 2d of the outer ring. The recesses 16b, 16c and the groove 16d also act as reservoirs filled with lubricant (not shown).
Since the faces 17, 18 of each spacer are identical in the illustrated embodiment, only one of them is described here, it being understood that the same references “a, b, c” are used for the identical elements of the two faces.
As shown on FIGS. 4 and 5, the face 17 comprises two identical and separate concave contact surfaces 17a, 17b having the shape of coaxial cylinder segments and a profile corresponding to the profile of the rolling surface of the associated roller 3a. As will be described latter, the axis of the cylinder segments of the contact surfaces 17a, 17b is not parallel to the axis of the cylinder segments of the contact surfaces 18a, 18b. Each circumferential end of each concave contact surfaces 17a, 17b is extended by a plane surface (not referenced) connected to a transversal edge of the associated planar contact surface 13a, 14a, 13b, 14b. The face 17 also comprises a concave recess 17c extending between said contact surfaces and which faces the roller 3a while remaining distant from the rolling surface of the latter. In the illustrated embodiment, the recess 17c has in cross-section a U-shape. The recess 17c extends transversally from a longitudinal edge of the contact surface 17a to a facing longitudinal edge of the other contact surface 17b. The recess 17c extends from the recess 13c of the inner part 13 to the recess 14c of the outer part 14. A joint edge of the recess 17c and the recess 14c is offset inwards with regard to the contact surfaces 14a, 14b of the outer part 14 and to the circumferential ends of the contact surfaces 17a, 17b of the face 17. Similarly, a facing joint edge of the recess 17c and the recess 13c is offset inwards with regard to the contact surfaces 13a, 13b of the inner part 13 and to the circumferential ends of the contact surfaces 17a, 17b of the face 17.
With the concave recess 17c, the friction contacts between the face 17 of each spacer and the associated roller are reduced. Besides, the recess 17c advantageously acts as lubricant reservoir for lubricating the concave contact surfaces 17a, 17b of the face and the rolling surface of the roller, the lubricant (not shown) emerging from the recess 17c directly onto said contact and rolling surfaces. Besides, the lubricant emerging from the recess 17c may be moved outward by centrifugal effect and reach the planar contact surfaces 14a, 14b of the outer part 14 and the associated raceway of the outer ring 2.
Each spacer 4 further comprises a through-hole 19 made inside its thickness, which opens onto the faces 17, 18 and put said faces into communication. On each face the through-hole 19 opens onto the recess 17c, 18c and the facing longitudinal edges of the contact surfaces 17a, 17b and 18a, 18b. Some lubricant (not shown) is disposed inside the through-hole 19, said hole acting as lubricant reservoir for lubricating the rolling surfaces of the two rollers associated to each spacer and the associated concave contact surfaces. The through-hole 19 allows the lubricant contained to emerge directly onto the rolling surface of each roller and the concave contact surfaces.
Otherwise, the recesses 15b to 15d of the lateral flange 15 of the spacer open onto the opposite concave contact surfaces 17b, 18b of the faces. Similarly, the recess 16b to 16d of the lateral flange 16 open onto the opposite concave contact surfaces 17a, 18a of said faces. Hence, the lubricant contained into the above-mentioned recesses may also emerge directly onto the concave contact surfaces of the faces 17, 18 and the end faces and the rolling surfaces of the associated rollers.
For each spacer 4, the presence of the recesses on the inner and outer parts 13, 14 and on the lateral flanges 15, 16 makes it possible to reduce the friction contacts with the rings, and to have a significant reserve of lubricant closed to the rollers 3a, 3b and to the raceways and the guiding faces of the rings. The friction contribution of each spacer 4 with regard to the inner and outer rings is thus reduced. Alternatively, it may however be possible to not foresee the recesses on the inner and outer parts 13, 14 and the lateral flanges for each spacer and to have one planar surface for each of said parts and flanges.
Otherwise, the presence of the recesses 17c, 18c on each spacer makes it possible to reduce the friction contacts with the rollers and to have a significant reserve of lubricant closed to the concave contact surfaces 17a, 17b and 18a, 18b and the rolling surfaces of said rollers. The friction contribution of each spacer 4 with regard to the rollers is thus reduced. Alternatively, it may however be possible to not foresee the recesses 17c, 18c nor the through-hole 19.
The general structure of each spacer 4 is lightened by the recesses. A weight reduction for each spacer is obtained. In the illustrated embodiment, each spacer 4 has a first symmetry plane passing through the grooves 15d, 16d of the lateral flanges and parallel to the planar contact surfaces of the inner and outer parts 13 and 14, a second symmetry plane passing through the recesses 13c, 14c and perpendicular to the first plane, and a third symmetry plane passing through the recesses 17c, 18c and parallel to the planar contact surfaces of the lateral flanges 15 and 16.
As above indicated, the axis of the cylinder segments of the contact surfaces 17a, 17b and the axis of the cylinder segments of the contact surfaces 18a, 18b converge. As shown on FIG. 7, the rotation axes 3′a of the rollers which are coaxial with the above-mentioned axes converge. The rotation axes 3′a of the rollers converge inwards of the rolling bearing. The thickness of the spacer 4 between the opposite faces 17, 18 gradually decreases from the lateral flange 15 to the other lateral flange 16. Advantageously, the minimum thickness tmin of the spacer is equal to or greater than 5% of the diameter of the associated roller. The minimum thickness tmin of the spacer may be equal to or greater than 5 mm. The minimum thickness tmin of the spacer and the maximum thickness tmax of the spacer are defined by




  1
  ,
  
    05
    ≤
    
      
        t
        
          ma
          ⁢
          
            
          
          ⁢
          x
        
      
      
        t
        
          m
          ⁢
          
            
          
          ⁢
          i
          ⁢
          
            
          
          ⁢
          n
        
      
    
    ≤
    4.
  




The medium thickness tmed is defined by





  
    
      
        t
        
          ma
          ⁢
          
            
          
          ⁢
          x
        
      
      +
      
        t
        
          m
          ⁢
          
            
          
          ⁢
          i
          ⁢
          
            
          
          ⁢
          n
        
      
    
    2
  
  .




For each row of contact rollers 3a, 3b of the rolling bearing, the number of contact rollers Zw of each row is defined by




  
    Z
    w
  
  ≤
  
    
      π
      ×
      
        d
        m
      
    
    
      
        d
        w
      
      +
      
        t
        med
      
    
  




and rounded to the lower integer value, with

dm corresponding to the bearing pitch diameter, i.e. the diameter of the circle that the centre point of a roller follows during rotation of the rolling bearing,
dw corresponding to the diameter of the rollers, and
tmed corresponding to the medium thickness of one spacer in the mid-plane containing the axes of the associated rollers.
The angle α given in degrees formed between the axes 3′a, or 3′b, of the two rollers associated to one spacer 4 is defined by




  α
  =
  
    
      360
      
        Z
        w
      
    
    .
  




With an angle between the two axes of the rollers in contact with the associated spacer 4, the skewing of said rollers is prevented under the action of the loads to which the rolling bearing is subjected in use.

For the introduction of the rollers 3a, 3b and the associated spacers 4 into the first and the second annular spaces defined between the inner and outer rings 1 and 2, said outer ring comprises two filling orifices (not shown) each extending radially from the outer cylindrical surface 2a and opening into one of the annular spaces delimited by the raceways and the guiding faces. The outer ring also comprises two plugs closing the filling orifices and each comprising two planar surfaces which respectively replace locally the raceway and the guiding face of the outer ring.
As shown on FIGS. 1 and 2, the inner and outer rings 1, 2 further respectively comprise axial holes 20, 21 for fixing the two rings to two parts of a machine which can rotate one with respect to the other by virtue of the rolling bearing.
The rolling bearing further comprises two annular seals 22, 23 positioned radially between the inner and outer rings 1, 2. The seal 22 is mounted axially between the rollers 3a and the radial surface 2b of the outer ring 2. The seal 23 is positioned axially between the rollers 3b and the radial surface 1c of the inner ring 1. The seal 23 is identical to the seal 22 and is positioned symmetrically with respect to the latter with regard to the radial plane passing through the center of the rolling bearing. A closed space is defined between the rings 1, 2 and the seals 22, 23 in which the rollers 3a, 3b are housed so as to be protected against polluting elements. In the disclosed embodiment, the seals 22 and 23 have in cross-section the overall shape of a H.
Although the invention has been illustrated on the basis of a rolling bearing having a double row of oblique contact rollers, it should be understood that the invention can be applied to bearings having a simple row of rollers or at least three rows of rollers. Otherwise, in the illustrated embodiments, the rolling bearings are O-type bearings. Alternatively, it may also be possible to foresee X-type rolling bearings.
Furthermore, the inner ring and/or the outer ring may comprise gearing teeth on their outer periphery, so as to be connected to driving gears for instance connected to the output shaft of a motor. In another embodiment, the inner ring and/or the outer ring may be connected to a jack, for example a hydraulic or pneumatic jack.


{'bibliographic_information': "{'country': 'US', 'doc-number': '14342476', 'kind': 'B2', 'date': '20110902', 'extension': '17', 'invention_title': 'Spacer for rolling bearing, notably used in a wind turbine'}", 'source_file': './grant/2016/ipg160517.xml', 'source_data': 'USPTO-Grant'}