Down-hole motor universal joint assembly

1. A universal joint (U-joint) assembly for transmitting torque from a drive component to a driven component across an articulating joint, comprising:

a female U-joint member coupled with the driven component, the female U-joint member defining a longitudinal axis and including a receptacle end, the receptacle end comprising:

a cavity extending into the receptacle end and terminating in a circular receptacle; and

four flat surfaces extending longitudinally from the cavity at 90-degree intervals about an inner diameter of the cavity; and

a male U-joint member coupled with the drive component and having a drive end, the drive end comprising four multi-angled surfaces extending longitudinally from the drive end at 90-degree intervals about a periphery of the drive end, wherein when the drive end of the male U-joint member is received coaxially within the cavity of the female U-joint member, each of the multi-angled surfaces of the drive end of the male U-joint member opposes a corresponding one of the four flat surfaces of the female U-joint member:

wherein the drive end of the male U-joint member further comprises a conical end cavity extending from a circular opening within the drive end to a concave semi-spherical bearing surface.

2. The U-joint assembly of claim 1 , further comprising a central ball seat including:

a circular base received within the circular receptacle of the female U-joint member; and

a central shaft positioned coaxial to the longitudinal axis, the central shaft extending proximally-to-distally from the circular base to a convex semi-spherical bearing surface configured to impinge upon the concave semi-spherical bearing surface of the conical end cavity of the male U-joint member.

3. The U-joint assembly of claim 2 , wherein the central ball seat further comprises a central grease passage extending along the longitudinal axis through the circular base and the central shaft.

4. The U-joint assembly of claim 2 , further comprising a retaining device configured to secure the cavity of the female U-joint member about the drive end of the male U-joint member.

5. A universal joint (U-joint) assembly for transmitting torque from a drive component to a driven component across an articulating joint, comprising:

a female U-joint member coupled with the driven component, the female U-joint member defining a longitudinal axis and including a receptacle end, the receptacle end comprising:

a cavity extending into the receptacle end and terminating in a circular receptacle; and

four flat surfaces extending longitudinally from the cavity at 90-degree intervals about an inner diameter of the cavity; and

a male U-joint member coupled with the drive component and having a drive end, the drive end comprising four multi-angled surfaces extending longitudinally from the drive end at 90-degree intervals about a periphery of the drive end, wherein when the drive end of the male U-joint member is received coaxially within the cavity of the female U-joint member, each of the multi-angled surfaces of the drive end of the male U-joint member opposes a corresponding one of the four flat surfaces of the female U-joint member;

wherein the male U-joint member further comprises a male threaded end opposing the drive end, the male threaded end configured to couple with a flexible drive shaft.

6. A universal joint (U-joint) assembly for transmitting torque from a drive component to a driven component across an articulating joint, comprising:

a female U-joint member coupled with the driven component, the female U-joint member defining a longitudinal axis and including a receptacle end, the receptacle end comprising:

a cavity extending into the receptacle end and terminating in a circular receptacle; and

four flat surfaces extending longitudinally from the cavity at 90-degree intervals about an inner diameter of the cavity; and

a male U-joint member coupled with the drive component and having a drive end, the drive end comprising four multi-angled surfaces extending longitudinally from the drive end at 90-degree intervals about a periphery of the drive end, wherein when the drive end of the male U-joint member is received coaxially within the cavity of the female U-joint member, each of the multi-angled surfaces of the drive end of the male U-joint member opposes a corresponding one of the four flat surfaces of the female U-joint member:

wherein the male U-joint member comprises a flexible drive shaft incorporating the drive end, the drive end separated from an opposing male threaded end by a flexible shaft disposed therebetween.

7. A method of transmitting a torque from a drive component to a driven component across an articulating joint, comprising:

coupling a universal joint (U-joint) assembly between the drive component and the driven component, the U-joint assembly comprising:

a female U-joint member coupled with the driven component, the female U-joint member defining a longitudinal axis and including a receptacle end, the receptacle end comprising a cavity extending into the receptacle end, the cavity terminating in a circular receptacle and including four flat surfaces extending longitudinally from the cavity at 90-degree intervals about an inner diameter of the cavity; and

a male U-joint member coupled with the drive component and having a drive end comprising four multi-angled surfaces extending longitudinally from the drive end at 90-degree intervals about a periphery of the drive end, the drive end received coaxially within the cavity of the female U-joint member such that each of the multi-angled surfaces of the drive end of the male U-joint member opposes a corresponding one of the four flat surfaces of the cavity of the female U-joint member;

articulating the male U-joint member relative to the longitudinal axis such that the male U-joint member is disposed at an articulation angle relative to the longitudinal axis; and

actuating the drive component such that the torque is transmitted from the male U-joint member to the female U-joint member through a contact area between select ones of the four multi-angled surfaces that are positioned parallel to the articulation angle of the male U-joint member and opposing ones of the flat surfaces of the female U-joint member;

wherein:

the male U-joint member further comprises a conical end cavity that terminates in a concave semi-spherical bearing surface; and

the U-joint assembly further comprises the central ball seat including a base received within the circular receptacle of the female U-joint member and a shaft extending along the longitudinal axis from the base to a convex semi-spherical bearing surface, wherein when the torque is transmitted from the male U-joint member to the female U-joint member, the convex semi-spherical bearing surface of the central ball seat impinges upon the concave semi-spherical bearing surface of the conical end cavity of the male U-joint member.

8. The method of claim 7 , wherein the U-joint assembly further comprises a retaining device including first and second semicircular segments configured to simultaneously threadably receive the female U-joint member and clamp about the male U-joint member to secure the female U-joint member about the central ball seat and the male U-joint member.

9. The method of claim 7 , further comprising coupling a flexible shaft between the drive end and the drive component.