Patent Publication Number: US-2023138660-A1

Title: Drive shaft assembly with constant velocity joints

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. Pat. Application No. 16/864,106 filed on Apr. 30, 2020, which is expressly incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention relates to joint assemblies for transmitting torque and, more particularly, to constant velocity joint assemblies for use in downhole drilling applications. 
     Description of the Related Art 
     Constant velocity joints for drive shafts can be associated with downhole motors used in the drilling industry for drilling boreholes for recovering reserves located in the geological formations, such as oil, gas, geothermal or the like. Drilling such boreholes requires transfer of large torque and axial thrust loads across the joints to rotate and advance a drill bit in the geological formations. 
     The rotary output shaft of conventional downhole motors used in the drilling industry moves in an eccentric manner, which must be converted into a concentric motion to rotate the drill bit of the drilling motor. This is commonly done using a drive shaft, having joints at each end, connecting the downhole motor to a drill bit assembly, thereby connecting the output member of the downhole motor to the input member of the drill bit assembly. 
     With the advancements in the field of directional drilling, torque transmitting and sustaining capabilities of the joints have become critical properties along with the reduction of vibrations to improve performance of the joints. Demand for improved performance has resulted in development of increased number of joint designs with various joint configurations to transmit torque. 
     Although some new designs improve the performance of the joints, their high design and manufacturing costs have prevented their wide spread use. However, there is still a demand for inexpensive and easily produced joints. 
     From the foregoing, there is a need for constant velocity joints having improved performance characteristics with low manufacturing cost. 
     SUMMARY 
     An aspect of the present invention includes a drive shaft assembly for a down hole drilling motor, comprising: a shaft extending along a first longitudinal axis of rotation, and having a first end portion and a second end portion, each end portion including: a circular base surface with a center on the first longitudinal axis of rotation and having a first and second prongs extending away from the base surface in the direction of the first longitudinal axis of rotation, wherein each of the first and second prongs has cylindrical sector shaped body, and a cylindrical side wall having a plurality of ball bearings held in a plurality of circumferentially spaced pockets; and a first housing extending along a second longitudinal axis of rotation, the first housing including: a first end including a first cavity for operatively receiving the first end portion of the shaft, the first cavity being separated from a second cavity located at a second end of the first housing by an internal wall having an internal wall surface, the first cavity including: an inner side wall including a plurality of cylindrical grooves, each of which mating with one of the plurality of ball bearings on the first end portion of the shaft to transfer torque between the shaft and the first housing with or without any angular offset between the first and second longitudinal axes of rotation, and a first chamber and a second chamber formed in the internal wall surface which are configured to receive and retain the first prong and the second prong to transfer torque and thrust loads between the first end portion of the shaft and the first housing while the circular base surface is supported on the internal wall surface; and a second housing, extending along a third longitudinal axis of rotation, having a first end and a second, the first end of the second housing having a first cavity for operatively receiving the second end portion of the shaft, wherein the circular base surface of the first end portion is a spherical surface having the center on the first longitudinal axis of rotation. 
     Another aspect of the present invention includes a constant velocity (CV) joint, comprising: a shaft extending along a first longitudinal axis of rotation, and having an end portion, the end portion including: a circular base surface, with a center on the first longitudinal axis of rotation, having a first and second prongs extending away from the base surface in the direction of the first longitudinal axis of rotation, wherein each of the first and second prongs has cylindrical sector shaped body, and a cylindrical side wall having a plurality of ball bearings held in a plurality of circumferentially spaced pockets; and a housing extending along a second longitudinal axis of rotation, the housing including: a first end including a first cavity for operatively receiving the end portion of the shaft, the first cavity being separated from a second cavity located at a second end of the housing by an internal wall having an internal wall surface, the first cavity including: an inner side wall including a plurality of cylindrical grooves, each of which mating with one of the plurality of ball bearings on the end portion of the shaft to transfer torque between the shaft and the first housing with or without any angular offset between the first and second longitudinal axes of rotation, and a first chamber and a second chamber formed in the internal wall surface which are configured to receive and retain the first prong and the second prong to transfer torque and thrust loads between the end portion of the shaft and the housing while the circular base surface is supported on the internal wall surface, wherein the circular base surface of the end portion is a spherical surface having the center on the first longitudinal axis of rotation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic illustration of an embodiment of a drive shaft assembly of the present invention including a first and second CV joints; 
         FIG.  1 B  is a schematic illustration of an embodiment of a drive shaft assembly assembled with an exemplary downhole motor; 
         FIG.  2 A  is a schematic illustration of an embodiment of a drive shaft of the present invention in side view having joint insert portions at opposing ends; 
         FIG.  2 B  is a schematic illustration of an embodiment of a CV joint of the present invention in an exploded view including a joint insert portion of a drive shaft and a housing; 
         FIG.  2 C  is a schematic illustration of a side view of an embodiment of a joint insert portion of a drive shaft with ball bearings; 
         FIG.  3 A  is a schematic illustration of an isometric view of an embodiment of a joint insert portion of a drive shaft without ball bearings, wherein the circular base surface of the joint insert portion is flat; 
         FIG.  3 B  is a schematic illustration of a top plan view of an embodiment of the joint insert portion of the drive shaft shown in  FIG.  3 A ; 
         FIG.  3 C  is a schematic illustration in side detail view of an embodiment of prongs of the joint insert portion of a drive shaft; 
         FIG.  4    is a schematic illustration of an isometric partial cut view of the interior of an embodiment of a joint socket portion of a housing of a CV joint having an internal wall including chambers to retain prongs, wherein the internal wall surface is flat; 
         FIG.  5 A  is a schematic plan view illustration of an embodiment of a socket cavity of the housing showing the inner wall with the cylindrical grooves and the internal wall including the chambers defined by the side walls, back walls and the bottom wall; 
         FIG.  5 B  is a schematic illustration of a cross-sectional view of the housing taken along the line 5B-5B in  FIG.  5 A ; 
         FIG.  6 A  is a schematic illustration of an embodiment of an assembled CV joint in side view including a joint insert portion of a drive shaft received by a housing; 
         FIG.  6 B  is a schematic illustration of a housing cap shown in a top view and a cross-sectional view taken along the center of the housing cap; 
         FIG.  6 C  is a schematic illustration in cut plan view taken along the lines 6C-6C in  FIG.  6 A  showing position of the prongs as being retained in the chambers of the housing of the assembled CV joint of the present invention; 
         FIG.  7 A  is a schematic illustration of an isometric view of an embodiment of a joint insert portion of a drive shaft without ball bearings, wherein the circular base surface of the joint insert portion is spherical; 
         FIG.  7 B  is a schematic illustration of a side view of an embodiment of joint insert portion of a drive shaft with ball bearings; 
         FIG.  8 A  is a schematic plan view illustration of an embodiment of a socket cavity of a housing showing the inner wall with the cylindrical grooves and the internal wall including the chambers defined by the side walls, back walls and the bottom wall; 
         FIG.  8 B  is a schematic illustration of a cross-sectional view of the housing taken along the line 8B-8B in  FIG.  8 A ,wherein the internal wall surface has at least partially concave shape; 
         FIG.  9    is a schematic illustration of an isometric partial cut view of an embodiment of the interior of a socket portion of a housing of the drive shaft assembly, wherein the internal wall surface is concave; 
         FIG.  10    is a schematic illustration of an embodiment of an assembled CV joint in side view including a joint insert portion of a drive shaft received by a housing, wherein the spherical base surface of the joint insert portion is supported by the concave inner wall surface; 
         FIG.  11 A  is a schematic illustration of an embodiment of a CV joint without an angular deflection between the drive shaft and the housing of the CV joint; 
         FIG.  11 B  is a schematic illustration of an embodiment of a CV joint showing an angular deflection between the drive shaft and the housing of the CV joint; 
         FIG.  12 A  is a schematic illustration of a position of the prongs within the chambers of the socket portion without any angular deflection of the CV joint of the present invention; and 
         FIG.  12 B  is a schematic illustration of a position of the prongs within the chambers of the socket portion during an angular deflection of the CV joint of the present invention. 
     
    
    
     It should be understood that the above referenced drawings are schematic, not necessarily drawn to scale, as their dimensions may be varied considerably without departing from the scope of the present disclosure. 
     DETAILED DESCRIPTION 
     Before explaining the present invention in detail, it is to be understood that the system is not limited to the particular embodiments and that it may be practiced or carried out in various ways. The present invention may provide an improved motor driveline, transmission and drive shaft. 
     Turning now to the figures,  FIG.  1 A  shows an exemplary embodiment of a drive shaft assembly  100  of the present invention, providing a constant velocity (CV) joint system for transmitting axial and rotational forces. The drive shaft assembly  100  may include a drive shaft  102  connecting two CV joints  104 , such as a first CV joint  104 A and a second CV joint  104 B, which will be referred to as the joint  104 A and the joint  104 B hereinafter. 
     In one embodiment, as shown in  FIG.  1 B , when assembled within a downhole motor  90  coupled to a drill string  80 , the drive shaft assembly  100 , through the joints  104 , may transfer both rotational torque and axial thrust loads from a power shaft  92  of the downhole motor to a bearing assembly  94  that rotates the drill bit  95 . As will be described more fully below, the joints  104 A,  104 B of the present invention may enable omni directional articulation of the drive shaft  102  to transfer both the rotational and axial forces. The parts of the downhole motor  90  and the drill bit  95  connected to the drive shaft assembly  100  of the present invention may include conventional elements or parts, with their operation principles, that will be known to one of skilled in the art and are not described herein. 
     Each joint  104 A,  104 B may include a housing  106 , such as the first housing  106 A and a second housing  106 B and joint insert portions  108 A and  108 B, or end portions  108 A and  108 B, located at both ends of the drive shaft  102 . Each housing  106 A and  106 B may include joint socket portions  110 A and  110 B and joint connector portions  112 A and  112 B respectively. The joint insert portions  108 A and  108 B of the drive shaft  102  may be movably received by the joint socket portions  110 A and  110 B of the housings  106 A and  106 B at both ends of the drive shaft  102 . The joint insert portions  108 A and  108 B of the drive shaft  102  may be movably retained within the joint socket portions  110 A and  110 B by the end caps  250  ( FIGS.  6 A and  6 B ) fastened to the joint socket portions  110 A and  110 B of the housings  106 A and  106 B at both ends of the drive shaft  102 . The joint connector portions  112 A and  112 B of the housings  106 A and  106 B may connect the joints to the bearing assembly  94  and a power shaft  92  of the drilling assembly shown in  FIG.  1 B , such as the joint  104 B to the power shaft  92  and the joint  104 A to the bearing assembly  94  of the drill bit  95 . 
     The drive shaft  102  may be a cylindrical rod extending along an axis ‘A’ which may be the rotational axis of the drive shaft  102 . Each of the first and second housings  106 A and  106 B has a generally cylindrical body which may extend along axes of rotation ‘B’ and ‘C’, respectively. Without any misalignment between the housings and the drive shaft  102 , the axis B and the axis C are aligned with the A axis as if a single axis of rotation for the drive shaft assembly  100 . During the operation of the drive shaft assembly  100 , there may be an angle between the A axis and B axis and C axis, i.e., offset angle or misalignment angle; or, zero angle between the A axis and B axis and C axis while transferring torque, speed and thrust. 
     The joints  104 A and  104 B may have substantively identical features and dimensions; therefore, embodiments below are generally described and exemplified with reference to one of the CV joints, such as the first CV joint  104 A. In this respect, the described and illustrated principles as well as features of the first CV joint  104 A may be substantively similar to the second CV joint  104 B. 
     Various features of the joint inserts  108 A,  108 B may be shown in  FIGS.  2 A,  2 B,  2 C,  3 A,  3 B, and  3 C . 
     Referring to  FIGS.  2 A,  2 B and  2 C , each joint insert portion  108  may include a generally cylindrical side wall  116  extending between a circular recess  118 , or annular recess  118 , and an end wall  120  of the joint insert portion  108 . The cylindrical side wall  116  may include a plurality of pockets  122 , or dimples  122 , positioned generally adjacent the end wall  120 . The pockets  122  may be annularly spaced around the cylindrical side wall  116  and may have spherical concave shape to hold a plurality of projections  123  extending radially from the cylindrical side wall  116 . The projections  123  may be integral part of the joint insert portion  108 , i.e., welded or manufactured by machining of the joint insert portion. As shown in  FIG.  2 B , the drive shaft joint insert portion  108 A with the projections  123  may be movably received by the joint socket portions  110 A of the housing  106 A to form the joint  104 A. 
     Referring to  FIGS.  2 B and  2 C , in one example the projections  123  may be spherical ball bearings, and there may be eight annularly spaced side pockets  122  on each joint insert portion  108  to hold eight ball bearings  123 , and the ball bearings  123  may be positioned adjacent the end wall  120 . As will be described more fully below, within the joints  104 , torsional load transfer occurs in a swivel section comprising the spherical surfaces of the ball bearings  123  on the joint insert portion  108  and the inner surfaces of the joint socket portion  110  of the housing  106 . 
     Referring to  FIGS.  3 A and  3 B , in one embodiment, the end wall  120  may have a flat circular end wall surface  124  to which the axis-A of the drive shaft  102  is perpendicular. The end wall  120  may include at least two thrust prongs  126 , or thrust lugs  126 , such as a first prong  126 A and a second prong  126 B, extending orthogonally away from the end wall surface  124 . The prongs  126  may have a three-dimensional (3D) body which may be identified as a generally wedge shape, or a pie-shape wedge in 3D, or a cylindrical sector shape. Each prong  126 A and  126 B may extend orthogonally away from their generally sector shape or quadrant shape base, or base area on the end wall surface  124  and terminate at a top surface  127  of each prong, which is also sector shape or quadrant shape. 
     Referring to  FIGS.  3 A and  3 B , in one embodiment, each prong  126 A,  126 B may have two flat side surfaces  128 A and  128 B meeting at prong corners  130 A and  130 B adjacent the center of the circular end wall surface  124  at an inner end of each prong. At an outer end of each prong  126 A and  126 B, the flat side surfaces  128 A and  128 B may terminate at curved side surfaces  132 A and  132 B. Each curved side surface  132 A,  132 B may extend from a lower end  134  of the curved side surface, where the curved side surface of the prongs joins the end wall surface  124 , to an upper end  136  of the curved side surface, where the curved side surface  132  joins the top surface  127 . The lower end  134  of the curved side surface  132  of the prongs  126   may be on the circumference of the circular end wall surface  124  or it may be placed concentrically adjacent the circumference of the surface  124  so that a circular surface strip  135  may be formed between the lower end  134  of the curved side surface  132  and the circumference of the circular end wall surface  124 . 
     Referring back to  FIGS.  3 A and  3 B , in one embodiment, the flat side surfaces  128 A and  128 B of the prongs  126 A,  126 B may be perpendicular to the end wall surface  124 . The distance ‘d’ between the prong corners  130 A and  130 B may be in the range of about 5 mm. The prongs  126 A and  126 B may be positioned symmetrically about the axis-A. The side surface  128 A of the first prong  126 A and the side surface  128 A of the second prong  126 B may be on the same diameter line of the circular end wall surface  124 . Similarly, the side surface  126 B of the first prong  126 A and the side surface  128 B of the second prong  126 B may be on the same diameter line of the circular end wall surface  124 . In one embodiment, the angle between the flat side surfaces  126 A and  126 B of each prong may be about 90 degrees or less than 90 degrees. 
     Referring to  FIGS.  2 C,  3 B and  3 C , in one embodiment, the curved side surface  132  and the top surface  127  of the prongs  126 A,  126 B may be inclined surfaces. The curved side surface  132  may be inclined by an α 1 -angle with respect to the surface normal of the end wall surface  124  while the top surface  127  may be inclined by an α 2 -angle with respect to the plane of the end wall surface  124 . As shown in  FIG.  3 C , due to the angled top surface  127  and the curved side surface  132 , prong height h 1  at the inner end or the prong corner  132  may be higher than the prong height h 2  at the outer end of the prongs  126 A,  126 B. In one embodiment, α 1  and α 2  angles may be in the range of about 2 to 5 degrees, and α 1  angle may be equal to α 2  angle. 
     The drive shaft  102  may be a cylindrical rod which may be a steel, metal alloy or metal. An exemplary drive shaft material may be a 4330 V alloy steel with about 150 psi min yield. The joint insert portions  108  at the opposing ends of the drive shaft may be made by quartering the ends along the diameter of the cylindrical rod and removing a pair of opposing wedge shaped portions by machining to form the prongs  126  with predetermined height on the end wall surface  124 . During the material removal process, the curved side surfaces  132  and the top surfaces  127  of the prongs  126 A,  126 B may be also appropriately angled by machining. The generally cylindrical sector or quadrant shaped prongs  126 A,  126 B may be smaller than the removed quarter portions to give them predetermined limited movability within the pair of chambers of the housing that receive them. Next, the cylindrical side wall  116  and the pockets  122  of the ball bearings  123  may be formed by machining. The ball bearings may be integral part of the pockets  122  by attaching the ball bearings to the pockets, such as, using welding or other fastening processes. Alternatively, the ball bearings  123  may be movably held by the pockets  122 . An exemplary drive shaft  102  may have the following dimensions: about 3″ diameter, about 36″ length and about 1″ prong height. 
     Referring to  FIGS.  4 ,  5 A,  5 B,  6 A,  6 B and  6 C , the housings  106  of the CV joints  104 A and  104 B may have a generally cylindrical body having an outer surface  107 . The housings  106 A and  106 B may have substantively identical features and dimensions; therefore, embodiments below are generally described and exemplified with reference to one of the housings, such as the first housing  106 A. In this respect, the described and illustrated principles as well as features of the first housing  106 A of the first CV joint  104 A may be substantively similar to the second housing  106 B of the second CV joint  104 B. The cylindrical body of the housing  106 A extends along the axis of rotation, denoted ‘B’, of the housing. The joint socket portion  110 A of the housing  106 A may include a socket cavity  140 A separated from a connector cavity  141 A of the joint connector portion  112 A by an internal wall  142  of the housing  106 A. In the socket cavity  140 A, the internal wall  142  may have a surface  145 , which may be a flat surface in one embodiment. In this embodiment, the B-axis of the housing  106 A may be orthogonal to the plane of the internal wall surface  145 . The cavities  140 A and  141 A of the housing  106 A may include a cylindrical socket opening  143 A and a cylindrical connector opening  143 B. 
     As shown in an isometric view in  FIG.  4   , a top view in  FIG.  5 A  and in side view in  FIG.  5 B , an inner side wall  144  of the socket cavity  140 A may include a plurality of cylindrical grooves  146 , or slots, extending parallel to the B-axis, which may mate with the ball bearings  123  on the cylindrical side wall  116  of the joint insert portion  108 A for torque transfer. The diameter of the ball bearings  123  mounted in the drive shaft  102  may be sized to correspond to the diameter of the cylindrical grooves  146 . The grooves  146  may be formed on the inner side wall  144  of the socket cavity  140 A and may extend between the internal wall surface  145  and an edge section  148 , having a threaded cylindrical surface, adjacent the socket opening  143 A of the socket cavity  140 A. As will be described below, an end cap  250  ( FIGS.  6 A- 6 B ) having mating threads engages the threaded edge section  148  of the housing  106 A by means of a mating threaded connection to hold the ball bearings  123  in the cylindrical grooves  146  and to movably retain the joint insert portion  108 A within the housing  106 A. The ball bearings  123  on the joint insert portion  108 A and the grooves  146  of the socket cavity  140 A may form swivel section of the CV joint  104 A enabling angular deflection of the CV joint  104 A of the present invention while transferring torque and speed. 
     The socket cavity  140 A may include at least two chambers  150  formed in the internal wall  142 , such as a first chamber  150 A and a second chamber  150 B to retain the prongs  126 A and  126 B. The chambers  150 A and  150 B may generally have matching quadrant profile of the prongs  126 A and  126 B to mate with the prongs  126 A and  126 B. The chambers  150 A and  150 B may include a base wall  152  or bottom wall  152 , surface of which may be, in one embodiment, parallel to the internal wall surface  145 , and chamber walls  154  extending between the internal wall surface  145  and the surface of the bottom wall  152  of the chambers  150 A,  150 B. The B axis of the housing  106 A is normal to the surface of the chamber bottom wall  152 . As shown in  FIG.  5 A , the chamber walls  154  may include side walls  154 A and back walls  154 B, which are perpendicular to the surface of the bottom wall  152 . In one embodiment, the chambers  150 A and  150 B may be connected at their inner ends toward the center of the internal wall  142 . The chambers  150 A,  150 B may be sized such that there may be a clearance between the surfaces of the chamber walls  154  and the flat side surfaces  128 A,  128 B and the curved side surfaces  132 A,  132 B of to prongs  126 A and  126 B to allow transfer of torque and thrust loads between the housing  106 A and the drive shaft  102  while the drive shaft  102  is articulated. In the joints  104 , the transfer of thrust may happen between the prongs  126  and the chamber walls  154 ,  152  and also between the end wall surface  124  and the internal wall surface  145 . 
     The housings  104  may be made of cylindrical rod which may be a steel, metal alloy or metal by machining, such as a 4330 V alloy steel with about 150 psi min yield. The chambers  150 A,  150 B may be formed into the circular internal wall  142  by quartering the circular surface along its diameter and removing a pair of opposing wedge shaped portions by machining to form the pair of straight walled cambers  150 A,  150 B with predetermined depth within the internal wall  142 . The generally cylindrical sector or quadrant shaped chambers  150 A,  150 B may be slightly larger than the prongs  126 A,  126 B to give them predetermined limited movability within the chambers of the housing that receive them. An exemplary housing for a 6 3/4 OD drilling tool may have the following dimensions: about 8″ length, an outside diameter of about 5″ and chamber depth of about 1″ for a drive shaft of about 3″ diameter, and about 1″ prong height. Ball bearings of the example joint insert portion may be about 1 1/8″ diameter rock bit balls and the diameter of the receiving cylindrical grooves of the housings may be about 2-50 thousandths larger than the diameter of the ball bearings. 
       FIG.  6 A  shows the first joint  104 A in side view and  FIG.  6 C  shows the prongs  126 A,  126 B in the chambers  150 A and  150 B in a cut plan view of the first joint  104 A. Referring to  FIGS.  6 A and  6 C , the joint insert portion  108 A of the drive shaft  102  is disposed within the housing  106 A to form the joint  104 A which provides omni directional motion between the drive shaft  102  and the housing  106 A while transferring torque and thrust loads across the drive shaft  102  and the housing  106 A during an operation of the drive shaft assembly  100 . When the insert portion  108 A is disposed within the socket cavity  140 A, the ball bearings  123  disposed in the grooves  146  of the socket cavity  140 A may primarily transfer torque or torsional loads between the drive shaft  102  and the housing  106 , and the prongs  126 A,  126 B disposed within the chambers  150 A,  150 B of the socket cavity  140 A may primarily transfer thrust or axial loads between the drive shaft  102  and the housing  106  during the operation of the CV joints. 
     Referring to  FIGS.  6 A and  6 B , an end cap  250 , or a retainer  250 , having mating threads engages the threaded edge section  148  of the housing  106 A by means of a mating threaded engagement to hold the ball bearings  123  in the cylindrical grooves  146  and to movably retain the joint insert portion  108 A of the drive shaft  102  within the housings  106 A. Similarly, the housing  106 B ( FIG.  1 A ) may also include an end cap to hold the ball bearings  123  in the cylindrical grooves  146  and to movably retain the joint insert portion  108 B within the housing  106 B. The end cap  250  may include an open ended cylindrical wall  252  having an outer surface  254  which has mating threads with the threaded edge section  148  of the housing  106 A. The cylindrical wall  252  may surround the joint insert portion  108 A and an upper end  256  of the cylindrical wall  252  may block the lower end of the cylindrical grooves  146 , thereby holding the ball bearings  123  within the cylindrical grooves and movably retaining the joint insert portion  108 A within the joint socket portion  110 A, when the end cap is installed. In the following figures the end cap will not be shown for clarity purposes. 
     Omni directional movement of the joint  104 A may be provided by the swiveling movement of the grooves  146  of the housing over the ball bearings  123  on the side wall  116  of the joint insert portion  108 A of the drive shaft  102 , and the contact of the prong surfaces, i.e., the top surfaces  127 , side walls  128  and the curved side walls  132  of the prongs  126 A,  126 B, with the surface of the chamber bottom wall  152 , the surfaces of the chamber side walls  154 A and the surfaces of the chamber back walls  154 B, as the prong surfaces abut the surfaces of the chamber walls by the axial and rotational movement of the prongs  126 A,  126 B. 
     In another embodiment of the present invention, both the flat internal wall surface  145  of the housings  104  and the flat end wall surface  124  of the joint insert portions  108  of the drive shaft  102 , described above, may be curved surfaces, such as mating spherical surfaces for smoother transfer of axial and rotational forces between the housings  104  and the drive shaft  102 . 
     As shown in  FIG.  7 A  and  FIG.  7 B , in an isometric view of the joint insert portion  104 A and its side cross sectional view along the prongs  126 , respectively, in this embodiment, the end wall  220  of the joint insert portion  108 A may be a convex-shaped or dome-shaped wall having a convex-shaped surface  224  or a dome-shaped surface  224 . In one embodiment the end wall may be a spherical wall  220  having a spherical surface  224 . An apex point or the surface center  224 A of the spherical surface  224  may be on the A axis of the drive shaft  102 . Depending on the diameter of the cylindrical joint insert portion  108 A, the curvature center Cs of the spherical surface  224  with the curvature radius Rs is on the axis A and may be below the level of the centers of the ball bearing  123 . 
     The prongs  126 A,  126 B may have the same cylindrical quadrant shape with the inner and outer heights h 1  and h 2  as the prongs described in the previous embodiment. The prong curved side surfaces  132  and the prong top surfaces  127  are substantially the same as the curved side surfaces  132  and the top surfaces  127  described in the previous embodiment. Due to the spherical shape of the end wall  220 , the surface area of the flat side walls  128 A,  128 B of the prongs may be gradually reduced in the direction of the spherical surface center  224 A. 
     As shown in  FIG.  8 A  and  FIG.  8 B , in a top view of the joint socket portion  110 A and its side cross sectional view along the internal wall  242 , respectively. In this embodiment, the internal wall  242  of the joint socket portion  110 A may include concave internal wall surface such as a spherical concave surface  245  having a slightly larger curvature radius than the curvature radius of the spherical end wall surface  224  of the joint insert portion  108 A. The curvature center Cs of the spherical surface  245  with the curvature radius Rs is on the B axis. 
       FIG.  9    shows in partial cut view of the housing  106 A having the concave internal wall surface  245 . In this embodiment, the depth or height of the chamber side walls  154 A may gradually decrease toward the center of the internal wall  242  so as to receive the spherical end wall surface  245  of the joint insert portion  108 A. The side walls  154 A and the back walls  154 B may extend between the flat bottom wall  152  and the spherical internal wall surface  245 . The B axis is normal to the flat bottom wall surface. 
       FIG.  10    shows in schematic side view of the joint  104 A of this embodiment formed by operatively engaged housing  106 A and the joint insert portion  108  of the drive shaft  102 . In this view, the prongs  126 A.  126 B are within the chambers  150 A,  150 B. In this embodiment, during the operation of the joint  104 A, the spherical end wall surface  224  including the prongs  126 A,  126 B of the joint insert portion  108 A may support the spherical internal wall surface  245  of the housing  106 A to transfer thrust more efficiently and help center the joint insert portion  108 A within the housing  106 A to increase performance of the joint  104 A. In this embodiment, in the joints  104 , the transfer of thrust may happen between the prongs  126  and the chamber walls  154 ,  152  and also between the spherical end wall surface  224  and the spherical internal wall surface  245 . 
     Referring to  FIGS.  11 A and  11 B , angular deflection of the joint  104 A of the present invention may be achieved by the swivel section of the joint  104 A, transferring torque and speed, in combination with prongs engaging with the chamber walls to transfer torque, speed and thrust, without needing a pivotal feature as in the prior art CV joints. The surfaces of the ball bearings  123  on the joint insert portion  108 A and the grooves  146  of the inner side wall  144  may form the swivel section of the CV joint  104 A which may enable angular deflection of the CV joint  104 A of the present invention, i.e. having an angle, for example β angle, between the A axis and B axis, while transferring torque, thrust and speed. 
     In this respect, the prongs  126 A,  126 B may have a range of motion within the chambers  150 A,  150 B to transfer torque and thrust to the housing  106 A or to the drive shaft  102 , by contacting, at least partially, the flat side surfaces  128 A,  128 B to the surfaces of the chamber side walls  154 A; by contacting, at least partially, the curved side surfaces  132  to the surfaces of the chamber back walls  154 B; and, by contacting, at least partially, the top surfaces  127  to the surface of the chamber bottom wall  152  that they face to. In addition, the prongs  126 A,  126 B may have a degree of freedom within the chambers  150 A,  150 B to move axially and provide angular deflection to the joint  104 A combined with the angular deflection provided by the swivel section of the joint  104 A. 
     Referring to  FIGS.  11 A,  11 B,  12 A and  12 B , in an example, to transfer torque and thrust, the angled curved side surfaces  132  and the angled top surfaces  127  of the prongs  126 A,  126 B may enable the prongs to limitedly angularly shift within the chambers  150 A,  150 B under a β angle, and with respect to the surfaces of the back wall  154 B of the chamber  150 B facing to the curved side surface  132  of the prong  126 B and the top surface  127  of the prong  126 A the facing to the surface of the chamber bottom wall  152  in the chamber  150 A. The top surface  127  of the prongs may be angled or flat. An angled top surface may be flat or outwardly curved, such as conical surface section. 
     In summary, the present invention may provide drive shaft assemblies utilizing constant velocity (CV) joints for support and torque transfer combined with interlocking joint prongs. As shown in the above described  FIGS.  1 A- 12 B , the ball bearings on the drive shaft ends may be used to align the joint, provide centering, and torque transfer while the interlocking prongs in the CV joints help transfer thrust, and provide additional torque support to create a long lasting low vibration driveshaft assembly. The ball bearings and the prongs placed on the exterior of the shaft are received in the mating housing cavity of the CV joints. A threaded cap may be installed to retain the ball bearings and the drive shaft assembly. When the shaft of the assembly is rotated, the CV joints move in a manner that allows the assembly to handle angular offset while maintaining near constant velocity. The ball bearings may provide centering for the prongs without utilizing a center pin as in the prior art jaw coupling designs. The resulting joint has lower vibration and extended life. The drive shaft assembly of the present invention allows for long life while minimizing vibrations, lowering operation costs, and offering predictable results. 
     Although aspects and advantages of the present invention are described herein with respect to certain embodiments, modifications of the embodiments will be apparent to those skilled in the art. Thus, the scope of the present invention should not be limited to the foregoing discussion, but should be defined by the appended claims.