Patent Publication Number: US-2022235818-A1

Title: Inner half-ring for a spherical plain bearing

Description:
CROSS-REFERENCE 
     This application claims priority to French patent application no. 2100720 filed on Jan. 26, 2021, the contents of which are fully incorporated herein by reference. 
     TECHNOLOGICAL FIELD 
     The present invention relates to an inner half-ring for a spherical plain bearing, and to a corresponding spherical plain bearing. 
     BACKGROUND 
     Split metal/metal spherical plain bearings are also known by the corresponding acronym “Split MA/ISPB”. Such spherical plain bearings have the specific feature of an inner ring split into two half-rings, the half-rings being assembled together so as to form the inner ring. 
     Although such a design of a spherical plain bearing is generally satisfactory, the space between the two half-rings may cause lubrication problems. Specifically, the lubricant can be supplied on the external diameter of the spherical plain bearing. In this case, it is desirable that the grease flows from the spherical zone corresponding to the external diameter as far as a bore zone located on the inside of the spherical plain bearing, in contact with the shaft. This inner zone is frequently a preferred friction zone during rotational movements, in the same way as the spherical zone. 
     However, it is generally found that, in the case of a split metal/metal spherical plain bearing, the grease flows towards the outside via the split interface between the two half-rings. This may cause a loss of pressure and thus prevent the grease from reaching the bore. 
     In order to overcome this drawback, provision has been made to add polytetrafluoroethylene (PTFE) inserts, in order to fill the gap between the two half-rings. However, the inserts can become detached over the service life of the spherical plain bearing and they increase the manufacturing cost. 
     SUMMARY 
     It is an aspect of the disclosure to address these drawbacks. 
     More particularly, an aspect of the disclosure is to improve the lubrication of a split metal/metal spherical plain bearing. 
     To that end, what is provided is an inner half-ring for a spherical plain bearing, the half-ring comprising a spherical outer surface, a cylindrical inner surface, a first and a second flat front face that delimit the half-ring in the circumferential direction, the first and second front faces extending between the outer surface and the inner surface. 
     According to a general feature, this half-ring comprises at least one first central groove formed on the first front face, the first central groove extending between the outer surface and the inner surface. 
     Such a central groove allows the grease injected between the inner ring and the outer ring to flow more towards the inside of the spherical plain bearing than towards the outside. This results in better lubrication of the spherical plain bearing. 
     In one embodiment, the first central groove extends radially. 
     According to another embodiment, the first front face is radial. 
     A linear channel formed on the outer surface at the edge where the outer surface meets the first front face may also be provided, the first central groove opening out in the linear channel. 
     The linear channel arranged in this way makes it possible to improve the effectiveness of the first central groove to allow the injected grease to flow. 
     The half-ring preferably also comprises a cutout, which opens out both on the outer surface and on the inner surface. The cutout may be a through opening connecting the inner surface to the outer surface. 
     Such a cutout, in conjunction with the groove, makes it possible to improve the flow of the grease towards the inside of the spherical plain bearing even further. 
     The cutout preferably extends radially. 
     An axial rectilinear channel formed on the inner surface may also be provided, the cutout opening out in the rectilinear channel. 
     The cutout and the rectilinear channel that are arranged with respect to one another in this way make it possible to improve very particularly the flow of the grease. 
     In one embodiment, the half-ring comprises a second central groove formed on the second front face, the second central groove extending between the outer surface and the inner surface. 
     Such a design makes it possible to improve the flow of the grease even further by making an additional central groove similar to the first central groove, thus increasing the manufacturing costs by only a small amount. 
     A first and a second secondary groove that are formed on the first front face and disposed on either side of the first central groove may also be provided. 
     In one embodiment, the first and second secondary grooves are parallel to the first central groove. 
     A circumferential channel may also be provided on the inner surface, the first central groove being disposed in the same axial plane as the circumferential channel. 
     As a result, the flow of the grease towards the inside of the spherical plain bearing is improved even further. 
     According to another aspect, a spherical plain bearing comprising an outer ring and an inner ring is proposed, the inner ring comprising at least one half-ring as defined above. 
     In one embodiment, the inner ring comprises two half-rings as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further aims, features and advantages of the invention will become apparent from reading the following detailed description, which is given purely by way of nonlimiting example and with reference to the appended drawings, in which: 
         FIG. 1  is a perspective view of an inner ring according to a first embodiment of the present disclosure which includes a first half-ring and a second half-ring. 
         FIG. 2  is a sectional view of the inner ring of  FIG. 1 . 
         FIG. 3  is a side elevational view of the first half-ring of  FIGS. 1 . 
         FIG. 4  is a sectional view of the first half-ring of  FIG. 3 . 
         FIG. 5  is a sectional view of an inner ring according to a second embodiment of the invention, which includes a first half-ring and a second half-ring. 
         FIG. 6  is a side elevational view of the first half-ring of the inner ring of  FIG. 5 . 
         FIG. 7  is a sectional view of the first half-ring of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , an inner ring  2  is schematically shown. The inner ring  2  is intended to be incorporated in a spherical plain bearing (not shown). In the example illustrated, the spherical plain bearing formed by the inner ring  2  is a split metal/metal spherical plain bearing. The spherical plain bearing comprises an outer ring (not shown) mounted in a swiveling manner against the outer surface of the inner ring  2 . 
     A direct orthonormal vector base  4  associated with the inner ring  2  is defined. The vector base  4  is composed of a vector X, a vector Y and a vector Z. 
     The inner ring  2  is intended to be received in an outer ring (not shown) so as to implement a swivel connection, namely a mechanical connection with three degrees of rotational freedom and zero degrees of translational freedom. It may also implement a linear annular connection, namely a mechanical connection with three degrees of rotational freedom and one degree of translational freedom. 
     The inner ring  2  is formed from two half-rings  6  and  8 . The half-rings  6  and  8  are partial elements that make up the inner ring  2 . 
     As can be seen in  FIGS. 2 to 4 , the half-rings  6  and  8  are substantially identical and symmetrical with respect to a plane that is perpendicular to the vector X. As a result, only the half-ring  6  will be described below, it being understood that this description also applies to the half-ring  8 . 
     The half-ring  6  has an outer surface  10 , an inner surface  12  and two front faces  14  and  16 . 
     The outer surface  10  is spherical about a center  18 . The outer ring (not shown) of the spherical plain bearing is thus mounted in spherical contact against the outer surfaces  10  of each half-ring  6  and  8 . The spherical outer surface  10  is truncated at two end faces  20  and  22 . The end faces  20  and  22  are flat and perpendicular to the vector Y. The end faces  20  and  22  have an outer contour that is circular about the vector Y. The circular outer contours of the end faces  20  and  22  have the same diameter d 20 - 22 . 
     The inner surface  12  is a cylinder of revolution about an axis  23  that includes the center  18  and is parallel to the vector Y. In the direction of the vector Y, the surface  12  extends between the end faces  20  and  22 . As a result, the inner contour of the end faces  20  and  22  is circular and the diameter d 12  of the inner surface  12  is equal to the diameter of the circular inner contour of the faces  20  and  22 , give or take the chamfers. 
     In the present application, the terms “radial”, “axial” and “circumferential”, and the terms derived therefrom, will be understood as referring to the cylindrical inner surface  12 . 
     Moreover, in the present application, the term “cylindrical” will be understood in accordance with its general definition, namely that a cylindrical surface is a surface made up of all the points on all the lines that are parallel to a given line and that pass through a plane curve set in a plane that is not parallel to the given line. 
     The front faces  14  and  16  are flat and perpendicular to the vector X. The front faces  14  and  16  are substantially disposed in one and the same plane that includes the center  18 . As a result, a radius of the outer surface  10  is substantially included in the plane of the faces  14  and  16 , which are therefore radial. 
     In the present application, it is understood that a surface is substantially disposed in the plane that includes the center  18  if this surface is offset with respect to such a plane by an offset less than or equal to the play typically present between the two half-rings of a split metal/metal spherical plain bearing. For example, in a split metal/metal spherical plain bearing with play, the offset in the direction of the vector X between the front face  14  or  16  and the center  18  can typically be between 0.3 mm and 0.4 mm. In a split metal/metal spherical plain bearing without play, the offset between the front face  14  or  16  and the plane that is perpendicular to the vector X and includes the center  18  can typically be between 0.03 mm and 0.07 mm. 
     The front faces  14  and  16  are delimited radially on the outside by the outer surface  10 . The front faces  14  and  16  are delimited radially on the inside by the inner surface  12 . The front faces  14  and  16  are axially delimited by the end faces  20  and  22 . The front faces  14  and  16  delimit the half-ring  6  in the circumferential direction. 
     The half-ring  6  has a central groove  24  on the front face  14  and a central groove  26  on the front face  16 . The grooves  24  and  26  face one another radially. The grooves  24  and  26  are central since they are equidistant, in the direction of the vector Y, from the end faces  20  and  22 . The central grooves  24  and  26  are rectilinear and radial. In other words, the central grooves  24  and  26  are oriented in the direction of the radius of the spherical outer surface  10 . In the example illustrated, the central grooves  24  and  26  are perpendicular to the axis  23 . 
     The central grooves  24  and  26  extend over the entire radial thickness of the front faces  14  and  16 , respectively, that is to say between the surfaces  10  and  12 . 
     As can be seen in  FIG. 3 , the half-ring  6  has four secondary grooves  28 ,  30 ,  32  and  34 . The secondary grooves  28  and  30  are on the front face  14 . The secondary grooves  32  and  34  are on the front face  16 . The secondary grooves  28  and  30  are disposed axially on each side of the central groove  24 . The secondary grooves  32  and  34  are disposed axially on each side of the central groove  26 . The secondary grooves  28 ,  30 ,  32  and  34  are rectilinear and perpendicular to the axis  23 . The secondary grooves  28 ,  30 ,  32  and  34  extend radially over the entire thickness of the half-ring  6 , that is to say between the surfaces  10  and  12 . 
     The grooves  24 ,  26 ,  28 ,  30 ,  32  and  34  have a semicircular cross section with the same diameter d 24 - 34 . Without departing from the scope of the invention, it is possible to envisage different diameters for the various grooves or else a first diameter for the central grooves  24  and  26  and a second diameter, different from the first diameter, for the secondary grooves  28 ,  30 ,  32  and  34 . 
     The half-ring  6  has a cutout  36 . The cutout  36  is rectilinear and radial. In the example illustrated, the cutout  36  is equidistant between the front faces  14  and  16 . The cutout  36  is parallel to the vector X. 
     The cutout  36  is through-opening. In other words, the cutout  36  extends radially between the surfaces  10  and  12 . The cutout  36  has a circular cross section with a diameter d 36  that is substantially equal to the diameter d 24 - 26 . 
     The half-ring  6  has a central linear channel  38 , two end linear channels  40  and two intermediate linear channels  42 . The linear channels  38 ,  40  and  42  are curved. 
     As can be seen in  FIG. 2 , the linear channels  38 ,  40  and  42  are on the outer surface  10 . More particularly, the end linear channels  40  are on the edge between the outer surface  10  and each of the front faces  14  and  16 . The central linear channel  38  is equidistant from the end linear channels  40 . Each intermediate linear channel  42  is equidistant from the central linear channel  38  and a respective end linear channel  40 . 
     The grooves  24 ,  28  and  30  thus open out radially on the outside in an end linear channel  40  and the grooves  26 ,  32  and  34  open out radially on the outside in the other end linear channel  40 . The cutout  36  opens out radially on the outside in the central linear channel  38 . 
     As can be seen in  FIGS. 3 and 4 , the half-ring  6  has a channel  44 . 
     The channel  44  is on the inner surface  12 . The channel  44  extends in the circumferential direction. As a result, the channel  44  is continuous in a plane that is perpendicular to the vector X. The channel  44  extends over the entire circumference of the inner surface  12  between the front faces  14  and  16 . The channel  44  is central or, in other words, is located equidistantly from the end faces  20  and  22 . 
     As a result, the central grooves  24  and  26  and the cutout  36  open out radially on the inside in the channel  44 . In other words, there is no axial offset between the cutout  36 , the central grooves  24  and  26  and the channel  44 . 
     The half-ring  6  has a central rectilinear channel  46 , two end rectilinear channels  48  and two intermediate rectilinear channels  50 . 
     The rectilinear channels  46 ,  48  and  50  are on the inner surface  12 . More specifically, the end rectilinear channels  48  are on the edge between the inner surface  12  and each of the front faces  14  and  16 . The central rectilinear channel  46  is equidistant from the end rectilinear channels  48 . Each intermediate rectilinear channel  50  is equidistant between the central rectilinear channel  46  and a respective end rectilinear channel  48 . 
     The rectilinear channels  46 ,  48  and  50  are parallel to the direction of the vector Y. The rectilinear channels  46 ,  48  and  50  have a length  146  of between 60% and 90% of the distance between the end faces  20  and  22 . 
     On account of this arrangement, the grooves  24 ,  26 ,  28 ,  30 ,  32  and  34  open out radially on the inside in the end rectilinear channels  48 . The cutout  36  opens out radially on the inside in the central rectilinear channel  46 . 
     The grooves  24 ,  26 ,  28 ,  30 ,  32  and  34  and the cutout  36  make it possible as a result to promote the flow of the lubricating grease towards the bore formed by the cylindrical inner surface  12 . The channels  38 ,  40 ,  42 ,  44 ,  46 ,  48  and  50  make it possible to improve this flow even further. This promoted flow is obtained whilst still ensuring that the half-ring  6  has good mechanical strength, by virtue of the relative arrangement of the grooves  24 ,  26 ,  28 ,  30 ,  32  and  34  and of the channels  38 ,  40 ,  42 ,  44 ,  46 ,  48  and  50  that has been described. 
     With reference to  FIGS. 5 to 7 , an inner ring  52  according to a second embodiment of the disclosure is schematically shown. The identical elements bear the same references. 
     The inner ring  52  differs from the inner ring  2  in that the half-rings  6  and  8  do not have secondary grooves  28 ,  30 ,  32  and  34 . In other words, only the central grooves  24  and  26  are provided on the front faces  14  and  16  of the half-rings  6  and  8 . 
     In this embodiment, the flow of the grease used to lubricate the split metal/metal spherical plain bearing can be improved, in particular between the bore defined by the cylindrical inner surface  12  and the outer spherical surface  10 . 
     Without departing from the scope of the invention, it is moreover possible to envisage providing only a single one of the two central grooves  24  and  26 . 
     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 inner rings for spherical plain bearings. 
     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. 
     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.