Abstract:
A universal joint includes a first shaft having a first member and a distal end. A first constant velocity joint is fixed to the first member and includes spherical balls to transmit a driving torque. A second shaft has a second member and a distal end. A second constant velocity joint is fixed to the second member, which also includes torque transmission spherical balls. A centering mechanism joins the first and second members and includes a semi-spherical female member connected to the first shaft distal end, and a male member having a semi-spherical portion rotatably received by the female member. The male member connects to the second shaft using a sliding joint and is axially displaceable relative to the second shaft such that universal joint displacement is equally divided between the first and second shafts.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates in general to rotational connection joints and more specifically to a device and method of manufacturing for a universal joint.  
       BACKGROUND OF THE INVENTION  
       [0002]     Universal joints of the double cardan type are known which are used to accommodate maximum drive line deflections up to approximately 25°. The double cardan joint is generally effective up to approximately 12° of drive line deflection at typical operating conditions. One disadvantage of the double cardan joint is that it is susceptible to increased wear and centering mechanism free play when operated at higher deflection angles. Another disadvantage of the double cardan joint is that it is also susceptible to damage by infiltration of dirt, etc. because the centering mechanisms of these joints are generally not sealed to prevent exposure to environmental conditions.  
         [0003]     An improvement to the double cardan joint includes a universal joint having two connected constant velocity joints. An example of this is provided in U.S. Pat. No. 3,857,256 to Girguis, issued Dec. 31, 1974. A similar joint design including seals to prevent dirt or environmental contamination of the constant velocity joints is provided in U.S. Pat. No. 3,593,541 to Kuroda, issued Jul. 20, 1971. These universal joint designs provide multiple constant velocity joints within an outer bearing race. Each constant velocity joint is fixed to either one of an input or an output shaft of the universal joint. Either the ends of the shaft or connections to the shaft are joined at about the center of the universal joint to evenly distribute the total displacement between both constant velocity joint assemblies of the universal joint. Rigid centering mechanism halves are provided to approximately divide the total displacement angle of the universal joint between both constant velocity joints. The rigid centering mechanism halves rely on proper alignment of the various universal joint components and generally provide only point contact between curved surfaces when the universal joints are in their displaced conditions.  
       SUMMARY OF THE INVENTION  
       [0004]     In one form, the present teachings provide a universal joint comprising a first shaft having a first axially extending member and a distal end. A first constant velocity joint is fixedly connected to the first axially extending member, the first constant velocity joint including a first plurality of spherical balls. A second shaft has a second axially extending member and a second shaft distal end. A second constant velocity joint is fixedly connected to the second axially extending member, the second constant velocity joint including a second plurality of spherical balls. A centering mechanism operably joins the first axially extending member to the second axially extending member, the centering mechanism including: a semi-spherical female member connectable to the first shaft distal end; and a male member having a semi-spherical portion rotatably receivable by the female member. The male member is slidably coupled to the second shaft.  
         [0005]     In another form, the present teachings provide a universal joint operable to transmit a driving torque having a first assembly including a first constant velocity joint fixedly connected to a first longitudinal shaft. A second assembly includes a second constant velocity joint fixedly connected to a second longitudinal shaft. A bearing race is operably engaged with both the first and second constant velocity joints, the bearing race operable to transmit the driving torque from the first constant velocity joint to the second constant velocity joint. A rotatable mechanism operably joins the first longitudinal shaft to the second longitudinal shaft, the rotatable mechanism including: a first bearing member connectable to the first longitudinal shaft, the first bearing member including a semi-spherical concave bearing surface; and a second bearing member having a flat contact end and a convex semi-spherical portion rotatably receivable by the concave bearing surface. A biasing element is disposed between the flat contact end and the second shaft operable to axially displace the second bearing member relative to the second shaft.  
         [0006]     The features, functions, and advantages can be achieved independently in various embodiments of the present inventions or may be combined in yet other embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIG. 1  is a side elevational, partial cross-sectional view of a high speed, high angle universal joint constructed in accordance with the teachings of the present invention;  
         [0009]      FIG. 2  is an end elevational view of the universal joint of  FIG. 1 ;  
         [0010]      FIG. 3  is a longitudinal cross-section view of the universal joint of  FIG. 1  showing a non-displaced condition of the universal joint;  
         [0011]      FIG. 4  is an enlarged, cross-sectional view of a centering mechanism constructed in accordance with the teachings of the present invention; and  
         [0012]      FIG. 5  is a longitudinal cross-section view similar to  FIG. 3 , showing an exemplary displaced condition of a universal joint constructed in accordance with the teachings of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0014]     Referring generally to  FIG. 1 , a universal joint  10  constructed in accordance with the teachings of the present invention can include an input shaft  12  having a flange  13  connected to a longitudinal shaft  14 . A first constant velocity (CV) joint  15  can be fixedly connected adjacent a shaft distal end  16 . Universal joint  10  can also include an output shaft  17  having a connector fitting  18  joined to a longitudinal shaft  19 . A second CV joint  20  can be fixedly connected to longitudinal shaft  19  adjacent a shaft distal end  21 . A centering mechanism  22  can be used to join longitudinal shaft  14  to longitudinal shaft  19 . An outer bearing race  24  can be externally mounted to the first CV joint  15  and the second CV joint  20  to transfer a drive torque from input shaft  12  to output shaft  17 . First CV joint  15  can include a plurality of spherical balls  26  and second CV joint  20  can include a plurality of spherical balls  27 . Each of the spherical balls  26  of first CV joint  15  and spherical balls  27  of second CV joint  20  can be rotatably mounted to a cage  28  or a cage  29 , respectively. Each of first CV joint  15  and second CV joint  20  can also include an inner bearing race  30  or an inner bearing race  31 , respectively, each rotatably supporting spherical balls  26  and spherical balls  27 , respectively. First CV joint  15  can be either slidably fit or press fit to a joint mounting surface  32  of longitudinal shaft  14 . Similarly, second CV joint  20  can be either slidably joined or press fit to a joint mounting surface  33  of longitudinal shaft  19 . Outer bearing race  24  can be provided with semi-spherical ball engagement surfaces  34   a  and  34   b  to rotatably engage spherical balls  26  and spherical balls  27 , respectively.  
         [0015]     Semi-spherical ball engagement surface  34   a  permits spherical balls  26  of first CV joint  15  to rotate in contact with semi-spherical ball engagement surface  34   a  thus permitting first CV joint  15  to rotate through an arc “A” about a CV joint axis of rotation “B”. CV joint axis of rotation B is positioned on a first CV joint centerline “C”. Second CV joint  20  is similarly rotatably mounted.  
         [0016]     Centering mechanism  22  can further include an adapter  35  having a male end  36  which can be slidably fit or press fit into a receiving aperture  37  of longitudinal shaft  14 . Male end  36  can be slid into receiving aperture  37  until adapter  35  engages shaft distal end  16 . Adapter  35  can also include a female end  38  which may be adapted to receive a concave bearing member  39 . Centering mechanism  22  can also include an adapter  40  having a mating end  41  which may be slidably fit or press fit into a receiving aperture  42  of longitudinal shaft  19 . Adapter  40  can be engaged with longitudinal shaft  19  until adapter  40  contacts shaft distal end  21  of longitudinal shaft  19 . A ball joint  44  can be slidingly engaged on a bearing end  43  of adapter  40  such that a convex surface of ball joint  44  contacts a concave mating surface of concave bearing member  39 . When first CV joint  15  and second CV joint  20  rotate in response to a deflection load, centering mechanism  22  can displace in a centering displacement path represented by arrows “D”. In a non-displaced condition for universal joint  10 , longitudinal shaft  14  and longitudinal shaft  19  can both align coaxially along a longitudinal axis  45  of universal joint  10 .  
         [0017]     To prevent environmental contaminants from entering universal joint  10 , a seal  46  having a shaft engagement end  48  can be secured to longitudinal shaft  14  using a clamp  50 , for example. A distal end  52  of seal  46  can be retained in a crimped end  54  of a seal cup  56 . Seal cup  56  can be matingly engaged with a first end  57  of outer bearing race  24 . Similarly, a seal  58  having a shaft engagement end  60  can be secured to longitudinal shaft  19  using a clamp  62 , for example. A distal end  64  of seal  58  can be retained within a crimped end  66  of a seal cup  68 . Seal cup  68  can be engaged with a second end  69  of outer bearing race  24  using a cupped end  70  of seal cup  68 . Material for seal  46  and seal  58  may be an elastomeric material known in the art, for example a compounded rubber.  
         [0018]     Referring generally to  FIG. 2 , flange  13  can include a plurality of fastener apertures  74  used to matingly engage flange  13  to a drive unit flange (not shown) providing driving torque to universal joint  10 . The plurality of fastener apertures  74  can be provided on a fastener or bolt circle  76 . The quantity of fastener apertures  74  can vary depending on a diameter  78  of flange  13 . Fastener apertures  74  can be initially located by positioning one of the fastener apertures  74  at an angle φ from a flange vertical centerline  80 . In the example shown, angle φ can be approximately 45 degrees. Remaining fastener apertures  74  are generally positioned at an aperture spacing angle ω. Aperture spacing angle ω for the exemplary application shown is approximately 90°, resulting in a total of four fastener apertures  74  for the example shown. Angle φ and aperture spacing angle ω can vary depending on the quantity of fastener apertures  74 , as well known to practitioners in the art.  
         [0019]     As generally seen in  FIG. 3 , in a non-displaced condition of universal joint  10 , longitudinal shaft  14  and longitudinal shaft  19  are both aligned coaxial to longitudinal axis  45 . First CV joint  15  is positioned in the non-displaced condition such that first CV joint centerline “C” is approximately perpendicular to longitudinal axis  45 . Similarly, a second CV joint centerline “E” of second CV joint  20  can also be perpendicularly aligned to longitudinal axis  45 . A bias element  82  can be disposed within a cavity  83  formed at an engagement end  84  of bearing end  43 . Bias element  82  can be a spring or similar biasing device providing a biasing force to direct ball joint  44  in a biasing direction “F”. In the non-displaced condition of universal joint  10  shown in  FIG. 3 , biasing direction “F” is coaxially aligned with longitudinal axis  45 .  
         [0020]     As more specifically shown in reference to  FIG. 4 , bias element  82  can contact a substantially flat contact end  85  of ball joint  44 . Ball joint  44  can be slidably disposed on bearing end  43  of adapter  40  using a plurality of pins  86 . Pins  86  can also be replaced by a bearing assembly such as a roller bearing assembly (not shown). Pins  86  can be disposed between a bearing surface  87  of bearing end  43  and an interior surface  88  of ball joint  44 . By slidably mounting ball joint  44 , ball joint  44  can move in a displacement path indicated by arrows “G”. The displacement path indicated by arrows “G” is substantially parallel to, and coaxially aligned with a longitudinal axis  89  of longitudinal shaft  19 .  
         [0021]     Referring generally to  FIG. 5 , a displaced condition for universal joint  10  is shown. In this example, a longitudinal axis  90  of longitudinal shaft  14  can be rotated downward from longitudinal axis  45 . In the displaced condition, longitudinal axis  90  forms an angle α with longitudinal axis  45  and longitudinal axis  89  of longitudinal shaft  19  forms an angle θ with longitudinal axis  45 . In this example, first CV joint  15  rotates counterclockwise from its initial or non-displaced condition wherein first CV joint centerline “C” is approximately perpendicular to longitudinal axis  45 , to a rotated centerline position “H”. First CV joint  15  therefore rotates relative to longitudinal axis  90 . First CV joint  15  centerline position “H” is rotated from first CV joint centerline “C” approximately half the angular rotation of angle α.  
         [0022]     Similarly, longitudinal shaft  19  can rotate such that longitudinal axis  89  is displaced below longitudinal axis  45 . Second CV joint  20  rotates clockwise about CV joint axis of rotation “J” between the second CV joint centerline “E” and a rotated centerline position “K”. Second CV joint  20  therefore rotates relative to longitudinal axis  89 . Second CV joint  20  centerline position “K” is rotated approximately half the angular rotation of angle θ. Flange  13  and connector fitting  18  both generally displace in a downward direction in the example shown in  FIG. 5 . Ball joint  44  of centering mechanism  22  translates in a displacement direction “L” substantially transverse to longitudinal axis  45  and opposite to the direction of displacement of flange  13  and connector fitting  18 . During the translation in displacement direction “L”, ball joint  44  is displaced by bias element  82  in a ball joint displacement path “M”. This displacement of ball joint  44  maintains ball joint  44  in substantial contact with concave bearing member  39 .  
         [0023]     Angle α can range between 0° up to about 7.5° in normal operating conditions, including high speed approximately 128.7 km/hr (80 mph) continuous driving operation. Angle α can typically range up to approximately 150 at a maximum deflection. The maximum deflection accommodates vehicle maximum suspension deflections permitting large road surface deflections of limited duration, off road vehicle operation or lifting the vehicle during maintenance. The maximum possible displaced condition for angle α can be determined when, for example, seal  46  compresses completely and longitudinal shaft  14  contacts crimped end  54  of seal cup  56  or alternately defined when adapter  35  contacts an internal surface of outer bearing race  24 .  
         [0024]     Longitudinal shaft  19  rotates in conjunction with oppositely directed longitudinal shaft  14  to form angle θ with longitudinal axis  45 . A maximum deflection for longitudinal shaft  19  is substantially equal to the maximum deflection of longitudinal shaft  14 , such that angle θ substantially equals angle α. The maximum deflection for longitudinal shaft  19  can be similarly limited by contact between seal  58  and crimped end  66  of seal cup  68  or contact between adapter  35  and the internal surface of outer bearing race  24 .  
         [0025]     For normal operating conditions the total deflection for universal joint  10  can be determined by adding angle α and angle θ. This results in an approximate 150 deflection range for normal operating conditions and a maximum deflection of approximately 300.  
         [0026]     Referring again to  FIG. 4 , first and second CV joints  15 , 20  can be provided with a plurality of splines  91 . A portion of the splines  91  of second CV joint  20  have been removed in  FIG. 4  to view exemplary ones of a plurality of corresponding splines  93  provided with race  31 . Race  30  also includes a plurality of splines  93 . First CV joint  15  can be fixedly engaged with longitudinal shaft  14  using a clip  92  inserted within a slot  94 . Slot  94  can be created within longitudinal shaft  14  for example by machining. Clip  92  can be a snap ring, a C-ring, or similar device. Clip  92  also mates within a mating slot  95  created in inner bearing race  30 . Second CV joint  20  can be retained in a similar manner.  
         [0027]     Referring again to  FIG. 1 , connector fitting  18  is exemplary of a plurality of fittings that can be used on the output end of universal joint  10 . In the embodiment shown, connector fitting  18  is adapted to connect to a tubular shaft  72  (shown in phantom), commonly known in the art for transferring a drive torque. Connector fitting  18  as well as flange  13  can be any type of fitting suitable for transmission of a drive torque, including flanges, couplings, weld joints, shaft fittings, threaded joints, etc. as known to a person of skill in the art.  
         [0028]     Materials for universal joint  10  are commonly known for universal joint application. Exemplary materials include 5120 steel, carburized and hardened for the cages  28  and  29 , the inner bearing races  30 , 31 , the outer bearing race  24 , the ball joint  44  and the concave bearing member  39 . Induction hardened steel can be used for the flange  13 , the connector fitting  18 , the longitudinal shafts  14  and  19  and the adapters  35  and  40 . Spherical balls  26  and  27  can be of high carbon steel, through-hardened and ground. These materials are exemplary only and can be replaced by materials as known to a person of skill in the art. A lubricant such as a high quality bearing grease is commonly inserted into universal joint  10  before seals  46 , 58  are clamped by clamps  50 , 62 , respectively.  
         [0029]     A universal joint of the present invention offers several advantages. By combining continuous velocity joints into a single universal joint a maximum deflection of about 30° can be achieved between an input and an output of universal joint  10 . By biasing a ball joint of a centering mechanism of the present invention, the ball joint is maintained in continuous contact over a greater surface area of a corresponding concave bearing member of the centering mechanism. This maintains alignment between components of the universal joint.  
         [0030]     While various preferred embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the invention and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.