Patent Publication Number: US-2023151850-A1

Title: Spherical plain bearing with angular misalignment restraint system, and angular misalignment restrain system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a non-provisional application of, and claims priority to U.S. Provisional Patent Application No. 63/278,926, entitled “Spherical Plain Bearing with Angular Misalignment Limiter,” filed on Nov. 12, 2021, the entire contents of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to spherical plain bearings, and more particularly to a spherical plain bearing with an angular misalignment restrain system configured to prevent damage to the bearing during maximum misalignment orientations. The present disclosure further relates to an angular misalignment restrain system for a spherical plain bearing. 
     BACKGROUND 
     Spherical plain bearings generally include inner and outer ring members wherein the outer ring member has a spherical concave interior surface that defines a cavity therein and wherein the inner member is disposed in the cavity and has a spherical convex surface that is complementary to, and is dimensioned to match, the concave interior surface of the outer ring member. In the assembled bearings, the concave and convex surfaces slide over each other to define the bearing surfaces or load zone. The bearings could have metal-to-metal contact of the concave interior surface with the convex surface with a lubricant (e.g., grease) disposed therebetween. Some spherical bearings employ a self-lubricating liner (e.g., a polytetrafluoroethylene liner) disposed between the concave interior surface and the convex surface. 
     Spherical plain bearings permit angular oscillation about a central point in two orthogonal directions (usually within a specified angular limit based on the bearing geometry). Typically, these bearings support a shaft that is rotatable in the bore of the inner ring that must move not only rotationally, but also at an angle that is referred to as angular misalignment. Some prior art spherical plain bearings tend to expose the concave and convex surfaces at maximum misalignment angles which can result in the ingress of contaminants into the bearing. The maximum misalignment can also damage the inner and outer member. 
     Thus, there is a need for an improved spherical plain bearing that overcomes the foregoing problems. 
     SUMMARY 
     According to aspects illustrated herein, a spherical plain bearing includes an outer ring that has an outer ring first axial end, an outer ring second axial end opposite to the outer ring first axial end, and a concave interior spherical surface that extends between the outer ring first axial end and the outer ring second axial end. The spherical plain bearing includes an inner member that has an inner member first axial end, an inner member second axial end opposite to the inner member first axial end and a convex exterior spherical surface between the inner member first axial end and the inner member second axial end. The inner member is pivotally disposed at least partially in the outer ring such that the inner member and the outer ring are angularly misalignable relative to one another. The spherical plain bearing includes an angular misalignment restraint (e.g., limiter) system that is configured in the outer ring and the inner member. 
     In some embodiments, the angular misalignment restraint system includes an inner member restraint feature on the inner member and an outer ring restraint feature on the outer member. 
     In some embodiments, a first portion of the inner member restrain feature is spaced apart from a second portion of the outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by less than a predetermined maximum angle θ, and the first portion of the inner member restrain feature is shaped and arranged to come into abutment with the second portion of the outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by the predetermined maximum angle θ. The abutment prevents any further angular misalignment of the inner member relative to the outer ring. 
     In some embodiments, the inner member restraint feature includes a radially outward extending lip formed on the first axial inner member end. The lip transitions into a concave arcuate valley which blends into the convex exterior surface of the inner member. The first portion includes the concave arcuate valley, which in some embodiments has a depth of 0.010 to 0.150 inches and a width of 0.020 to 0.300 inches. 
     In some embodiments, the outer ring includes a radially outward extending first circumferential groove that is located proximate the outer ring first axial end and extends radially out into a first cylindrical shoulder. The outer ring restraint feature includes an annular bumper pad that has an anchor leg secured in the first circumferential groove and a head portion that extends from the anchor leg and circumferentially around the bumper pad. The second portion includes the head portion. 
     In some embodiments, the head portion has a convex arcuate surface that is complementary in shape to the concave arcuate valley. The convex arcuate surface has a first radius of curvature and the concave arcuate valley has a second radius of curvature. The second radius of curvature is about 100 to 120 percent of the first radius of curvature. Preferably, the second radius of curvature is about 102 percent of the first radius of curvature. 
     In some embodiments, a self-lubricating liner is disposed between the concave interior spherical surface and the convex exterior spherical surface. 
     In some embodiments, the outer ring has one or more splits that extend axially from the first axial outer ring end to the second axial outer ring end and radially through the outer ring. 
     In some embodiments, the outer ring includes a radially outward extending second circumferential groove that is located proximate the second axial outer ring end and an annular seal seated in the second circumferential groove. A portion of the seal sealingly and slidingly engages the convex exterior spherical surface. 
     In some embodiments, the outer ring includes a radially outward extending second circumferential groove located proximate the outer ring second axial end and extending radially out into a second cylindrical shoulder. A second outer ring restraint feature (i.e., an annular bumper pad that has an anchor leg secured in the second circumferential groove and a head portion extending from the anchor leg and extending circumferentially around the bumper pad). 
     In some embodiments, the outer member restraint feature is configured in an interference fit with the convex exterior spherical bearing surface of the inner member to function as a seal. 
     In some embodiments, the inner member restrain feature is an arcuate surface or a chamfer. 
     In some embodiments, the angular misalignment restraint system is a first angular misalignment restraint system, and the spherical plain bearing comprises a second angular misalignment restraint system including a second inner member restraint feature on the inner member and a second outer ring restraint feature on the outer member. The first angular misalignment restrain system is on the outer ring first axial end and the inner member first axial end, and the second angular misalignment restrain system is on the outer ring second axial end and the inner member second axial end. A first portion of the second inner member restrain feature is spaced apart from a second portion of the second outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by less than the predetermined maximum angle θ. The first portion of the second inner member restrain feature is shaped and arranged to come into a second abutment with the second portion of the second outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by the predetermined maximum angle θ. The second abutment prevents any further angular misalignment of the inner member relative to the outer ring. 
     According to aspects illustrated herein, an angular misalignment restraint system for a spherical plain bearing includes an inner member restraint feature on the inner member of the spherical plain bearing, and an outer ring restraint feature on the outer member of the spherical plain bearing. A first portion of the inner member restrain feature is spaced apart from a second portion of the outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by less than a predetermined maximum angle θ. The first portion of the inner member restrain feature is shaped and arranged to come into abutment with the second portion of the outer ring restraint feature when the inner member and the outer ring are angularly misaligned relative to one another by the predetermined maximum angle θ. The abutment prevents any further angular misalignment of the inner member relative to the outer ring. 
     Any of the foregoing embodiments may be combined. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Referring now to the Figures, which are exemplary embodiments, and wherein the like elements are numbered alike: 
         FIG.  1    is cross-sectional view of an exemplary spherical bearing of the present disclosure shown in a zero-angle misalignment state; 
         FIG.  2 A  is a cross-sectional view of the spherical bearing of  FIG.  1    in a state of maximum misalignment; 
         FIG.  2 B  is an enlarged cross-sectional view of a portion of the spherical bearing of  FIG.  2 A ; 
         FIG.  3 A  is an end view of the outer ring restraint feature of the spherical bearing of  FIG.  1   ; 
         FIG.  3 B  is an end view of the outer ring of the spherical bearing of  FIG.  1   ; 
         FIG.  4 A  is another enlarged cross-sectional view of a portion the spherical bearing of  FIG.  2 A ; 
         FIG.  4 B  is a cross-sectional view of a portion of another exemplary embodiment of the spherical bearing in a state of maximum misalignment; 
         FIG.  5 A  is a cross-sectional view of another exemplary embodiment of a spherical bearing in a zero-angle misalignment state; 
         FIG.  5 B  is a cross-sectional view of the spherical bearing of  FIG.  5 A  in a state of maximum misalignment; 
         FIG.  6    is a cross-sectional view of another exemplary embodiment of the spherical bearing of the present disclosure shown in a zero-angle misalignment state and having a pin extending therethrough; and 
         FIG.  7    is a cross-sectional view of another exemplary embodiment of the spherical bearing of the present disclosure shown in a zero-angle misalignment state and having a ball stud extending therethrough. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIG.  1   , a spherical plain bearing is generally designated by the number  10 . The bearing  10  includes an outer ring  20  and an inner member  30  disposed partially in the outer ring  20 . The inner member  30  and the outer ring  20  are angularly misalignable relative to one another as shown in  FIGS.  2 A and  2 B . The bearing  10  is shown in  FIG.  1    in a zero-angle misalignment state wherein both the inner member  30  and the outer ring  20  are coaxial with the longitudinal axis L. 
     The outer ring  20  has an outer ring first axial end  20 A and an outer ring second axial end  20 B opposite to the outer ring first axial end  20 A. The outer ring  20  has a concave interior spherical bearing surface  22  between the outer ring first axial end  20 A and the outer ring second axial end  20 B. The concave interior spherical bearing surface  22  defines an opening  24 . 
     As shown in  FIG.  1   , the inner member  30  is a solid truncated spherical ball that has an inner member first axial end  30 A and an inner member second axial end  30 B opposite to the inner member first axial end  30 A. While the inner member  30  is shown in  FIG.  1    as being a solid truncated spherical ball, the present disclosure is not limited in this regard as other configurations are included in the present disclosure including but not limited to the spherical bearing shown in  FIGS.  5 A and  5 B . 
     As shown in  FIGS.  1  and  5 A , the outer ring first axial end  20 A and the inner member first axial end  30 A are parallel to one another when the outer ring  20  and the inner member  30  are positioned coaxially with a longitudinal axis L with no angular misalignment. The inner member  30  has a convex exterior spherical bearing surface  36  that is located between the inner member first axial end  30 A and the inner member second axial end  30 B. As shown in  FIG.  1   , the convex exterior spherical bearing surface  36  of the inner member  30  substantially conforms in shape to the concave interior spherical bearing surface  22  of the outer ring  20 , and the inner member  30  is received in the opening  24  of the outer ring  20 . The convex exterior spherical bearing surface  36  is complementary in shape to the concave interior spherical bearing surface  22 . The bearing  10  has an angular misalignment restraint (e.g., limiter) system  50  (see  FIG.  2 B ) on the outer ring  20  and the inner member  30  as described herein. The angular misalignment restraint system  50  has utility in preventing damage due to excessive misalignment in bearings utilized in various systems including but not limited to bearings and linkages in vehicle suspension systems. 
     As shown in  FIG.  2 B , the angular misalignment restraint system  50  includes an inner member restraint feature  60  on the inner member  30  proximate the inner member first axial end  30 A and an outer ring restraint feature  70  on the outer member  20  proximate the outer ring first axial end  20 A. The inner member restraint feature  60  includes a radially outward extending lip  62  formed on the inner member first axial end  30 A. The axial lip  62  is an arcuate surface that has a radius of curvature R 3  (see  FIG.  4 A ) transitions into a concave arcuate valley  64  which blends into the convex exterior surface  36  of the inner member  30 . In some embodiments, the concave arcuate valley  64  has a depth D of 0.010 to 0.150 inches and a width W of 0.020 to 0.300 inches, depending on the bearing size. While the lip  62  is shown in  FIG.  4 A  as having a radius of curvature R 3 , the present disclosure is not limited in this regard as other configurations are included in the present disclosure such as but not limited to the lip  63  having a chamfer (i.e., flat) configuration as shown in  FIG.  4 B . 
     As shown in  FIG.  2 B , the outer ring  20  has a radially outward extending circumferential groove  24 B located proximate the outer ring first axial end  20 A and in a cylindrical shoulder  23  that extends axially inward from the outer ring first axial end  20 A. The outer ring restraint feature  70  includes an annular bumper pad  70  that has an anchor leg  70 B secured in the groove  24 B and a head portion  70 A extending from the anchor leg  70 B and extending circumferentially around the bumper pad  70 . The head portion  70 A has a convex arcuate surface that is complementary in shape to the concave arcuate valley  64 . 
     In some embodiments, a mid-portion  70 C of the annular bumper pad  70  has a shape that is complementary (e.g., concave spherical) to the exterior surface  36  of the inner member  30 , and is configured to slide on the exterior surface  36  during misalignment movement. However, in other embodiments, the mid-portion  70 C of the annular bumper pad  70  does not have a shape that is complementary to the exterior surface  36  of the inner member  30 , and does not slide on the exterior surface  36  during misalignment movement. The mid-portion  70 C can operate as an anti-rotation feature that assists in preventing the anchor leg  70 B of the bumper pad  70  from dislodging from the groove  24 B during mis-alignment movement. 
     As shown in  FIG.  4 A , the radially outward extending circumferential groove  24 B has a width L 1  of about 0.025 inches to about 0.250 inches. The radially outward extending circumferential groove  24 B is located a distance L 2  of about 0.025 inches to about 0.250 inches measured axially inward from the outer ring first axial end  20 A. The head portion  70 A has length T 1  of about 0.050 inches to about 0.500 inches measured radially inward from the cylindrical shoulder  23 . 
     As shown in  FIGS.  2 A and  2 B , the inner member  30  and the outer ring  20  are angularly misaligned relative to one another by a predetermined maximum angle θ. The head portion  70 A of the outer ring restraint feature  70  engages the concave arcuate valley  64  of the inner member restraint feature  60 , to prevent any further angular misalignment of the inner member  30  relative to the outer ring  20 . As shown in  FIG.  4 A , at a maximum angle of misalignment θ the head portion  70 A of the outer ring restraint feature  70  imparts a force F 1  on the lip  62  and the concave arcuate valley  64  which counteracts the force F 1  with a reaction force F 2 . 
       FIG.  1    shows that the concave arcuate valley  64  of the inner member restraint feature  60  and the head portion  70 A of the outer ring restraint feature  70  are spaced apart when the inner member  30  and the outer ring  20  are angularly misaligned relative to one another by less than a predetermined maximum angle θ (e.g., the angle θ shown in  FIG.  1    is zero). By contrast,  FIGS.  2 A and  2 B  show that the concave arcuate valley  64  of the inner member restraint feature  60  is shaped and arranged to come into abutment with the head portion  70 A of the outer ring restraint feature  70  when the inner member  30  and the outer ring  20  are angularly misaligned relative to one another by the predetermined maximum angle θ. This abutment prevents any further angular misalignment of the inner member  30  relative to the outer ring  20 . 
     As shown in  FIGS.  2 A and  2 B , a self-lubricating liner  80  is disposed between the concave interior spherical surface  22  and the convex exterior spherical surface  36 . In some embodiments, the self-lubricating liner  80  is secured (e.g., adhered) to the concave interior spherical surface  22 . The self-lubricating liner  80  is a woven fabric that includes polytetrafluoroethylene (PTFE) or molded PTFE material. 
     The annular bumper pad  70 , shown for example in  FIG.  3 A , is made from a tough plastic material with high abrasion and wear resistance such as an ultra-high molecular weight (UHMW) polyethylene material. While the bumper pad  70  is described as being made from UHMW polyethylene material, the present disclosure is not limited in this regard as other materials for the bumper pad  70  are included in the present disclosure such as but not limited to brass, bronze, thermoplastics (delrin, acetal, teflon, polyester), elastomers (polyurethane, nitrile, silicone) and thermoplastic elastomers inventors please provide other options for materials. 
     As shown in  FIG.  4 A , the head portion  70 A has a convex arcuate surface  77  that is substantially complementary in shape to the concave arcuate valley  64 . The convex arcuate surface  77  has a first radius of curvature R 1  and the concave arcuate valley  64  has a second radius of curvature R 2 . In some embodiments, the second radius of curvature R 2  is about 100 to 120 percent of the first radius of curvature R 1 . In some embodiments, the second radius of curvature R 2  is about 102 percent of the first radius of curvature R 1 . 
     As shown in  FIG.  3 B , the outer ring  20  has two fracture splits  20 X and  20 Y that extend axially from the outer ring first axial end  20 A to the outer ring second axial end  20 B and radially through the outer ring  20 . The two fracture splits  20 X and  20 Y facilitate assembly of the outer ring  20  and bumper pad  70  over the inner member  30 . While two axial splits are shown and described, the present disclosure is not limited in this regard as the outer ring  20  may employ only one fracture split or more than two fracture splits. 
     As shown in  FIG.  1   , the outer ring  20  has a radially outward extending second circumferential groove  23 B located proximate the second axial outer ring end  20 B outward into and circumferentially along a cylindrical shoulder  23  that extends axially inward from the second axial outer ring end  20 B. An annular seal  40  is disposed in the seal groove  23 B. An annular seal  40  is seated in second circumferential groove  23 B. A portion of the seal  40  sealingly and slidingly engages the convex exterior spherical surface  36 . 
     The inner member  30  is manufactured from a metallic material such as a SAE-AISI 52100 steel, SAE-AISI 8620 steel, stainless steel or bronze. The outer ring  20  is manufactured from a metallic material such as SAE-AISI 52100 steel, SAE-AISI 8620 steel and stainless steel. In some embodiments, the inner member  30  and/or the outer ring  20  are coated with a suitable protective coating such as, but not limited to a zinc, a black oxide and a chromium coating. 
     The spherical bearing  10 ′ of  FIGS.  5 A and  5 B  is similar to the spherical bearing  10  of  FIG.  1    with the exception that the spherical bearing  10 ′ includes another inner member restraint feature  60 ′ (i.e., axial lip  62 ′ which transitions into a concave arcuate valley  64 ′) on the inner member  30  proximate the inner member second axial end  30 B and another outer ring restraint feature  70 ′ on the outer member  20  proximate the outer ring second axial end  20 B, in addition to the inner member restraint feature  60  on the inner member  30  proximate the inner member first axial end  30 A and outer ring restraint feature  70  on the outer member  20  proximate the outer ring first axial end  20 A. In the embodiment shown in  FIGS.  5 A and  5 B  the spherical bearing  10 ′ has no seal similar to the seal  40  shown in  FIG.  1   , however in some embodiments the spherical bearing  10 ′ includes a seal seated in a circumferential groove similar to the seal  40  and circumferential groove  23 B shown in  FIG.  1   . In some embodiments, the outer ring restraint feature  70  (i.e., bumper pad) and/or the outer ring restraint feature  70 ′ are configured in an interference fit with the exterior surface  36  of the inner member  30  to function as a seal. 
       FIG.  5 A  shows that the concave arcuate valley  64 ′ of the inner member restraint feature  60 ′ and a head portion of the outer ring restraint feature  70  are spaced apart when the inner member  30  and the outer ring  20  are angularly misaligned relative to one another by less than the predetermined maximum angle θ (the angle being zero, as illustrated). By contrast,  FIG.  5 B  shows that the concave arcuate valley  64 ′ of the inner member restraint feature  60 ′ is shaped and arranged to come into abutment with the head portion of the outer ring restraint feature  70 ′ when the inner member  30  and the outer ring  20  are angularly misaligned relative to one another by the predetermined maximum angle θ. This abutment prevents any further angular misalignment of the inner member  30  relative to the outer ring  20 . 
     The spherical bearing  110  shown in  FIG.  6    is similar to the spherical bearing  10  of  FIG.  1   , except that the inner member  30  has a bore  39  extending therethrough and a pin  38  extending through the bore  39 . 
     The spherical bearing  210  shown in  FIG.  7    is similar to the spherical bearing  10  of  FIG.  1   , except that the inner member  30  has a stud  37  extending axially therefrom. 
     While the present disclosure has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.