Universal joint

Abstract

A universal joint assembled in a drill string transfers torque between two components where the shafts of the components are not completely aligned. The universal joint includes two members each with pin connections on one end and axially extending arms on the other end. The axially extending arms intermesh when the members are assembled defining a closed cavity between the arms. The cavity retains a ball bearing held between two seats. The universal joint when assembled to portions of the drill string at the pins on each end transfer torque by intermeshing of the teeth. Axial force is transferred through the seats holding the ball bearing.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to universal joints and more particularly to universal joints used in downhole drill strings.GENERAL BACKGROUND[0002]In a drilling operation a drill bit is mounted to the end of a drill string. The drill string is rotated from the top of the string or by a motor at the bottom of the string, or both, to rotate the drill bit and advance the borehole. Universal joints are included in the drill string to accommodate eccentricity in the string. The eccentric rotation must be converted into concentric rotation in order for the drill bit to advance the borehole efficiently. Eccentricity in the drill string may be initiated by a motor in the drive assembly that rotates the drill bit or by steering of the bit to change direction of the borehole.[0003]The components of the drill string including the universal joint are subjected to extreme torque forces, elevated operating temperatures and abrasive drilling fluids, all of which can ...

AI Technical Summary

Benefits of technology

The patent text discusses the use of abrasive particles in drilling fluids and how they can damage the bearing surfaces of universal joints. This can limit the lifespan of these joints. However, the text also suggests the use of a ball bearing in the joint, which can continually rotate and present a new bearing face to the opposing bearing seat, extending its service life. The use of a ball bearing can also make the drill string more compact, allowing the components to be positioned closer together. This patent text explores different ways to improve the performance and longevity of universal joints in drilling operations.

Problems solved by technology

This can severely limit the service life of universal joints with fixed bearing elements such as a rod with bearing surfaces at the end of the rod such as used in conventional joints.

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