Universal Joint With Planar Bearing For Drill String
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Solution Overview
Problem
Conventional universal joints in downhole drill strings face challenges due to extreme torque forces, elevated temperatures, and abrasive drilling fluids, leading to erosion, abrasion, and reduced operational life, necessitating frequent replacements and substantial downtime.
Innovation Solution
A universal joint design featuring a flat or planar bearing element with limited moving parts, radially and angularly spaced connections, and integrated service life indicators to monitor wear and overstress, allowing for compact assembly and reduced erosion, along with a ball bearing system for axial load transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional sealing arrangements are used in universal joints, then the joint can accommodate rotational eccentricity, but the components are subject to erosion and abrasion from abrasive drilling fluids, reducing operational life
Solution Approach 1:
The patent removes conventional sealing arrangements from the universal joint design. Instead of using seals that would trap abrasive drilling fluids against moving components, the design allows the joint to operate without seals, accepting that some fluid contact occurs but eliminating the sealing interfaces that would otherwise erode and fail prematurely in the abrasive downhole environment.
2Power
If high normal force components with sliding or rotating contact surfaces are used, then torque can be transmitted between misaligned components, but erosion from abrasive drilling fluids increases
Solution Approach 1:
The patent employs spherical bearing elements (balls) that roll between the yoke and cross components. This spherical geometry converts sliding contact into rolling contact, dramatically reducing erosion from abrasive drilling fluids while maintaining the ability to transmit torque between misaligned components. The curved surfaces of the balls distribute contact forces and minimize wear.
3Adaptability or versatility
If multiple moving parts and components are used in the universal joint, then rotational eccentricity can be accommodated, but the assembly becomes complex and manufacturing costs increase
Solution Approach 1:
The patent divides the universal joint into four identical yoke arms and four identical cross arms, each with similar structural features. This segmentation allows for standardized manufacturing of repeated components, simplifying production despite the multi-component nature of the assembly. The modular design makes it easier to manufacture and assemble while maintaining the complex motion accommodation capability.
4Length of moving object
If conventional drill string components are used, then the drill string can reach the bottom of the wellbore, but replacement requires removal of the drill string from the borehole, causing substantial downtime
Solution Approach 1:
The patent incorporates wear indicators (such as colored bands or markers on the bearing balls) that allow operators to monitor component wear while the drill string remains in the borehole. When wear reaches a predetermined threshold indicated by the wear indicators, the universal joint can be replaced without extracting the entire drill string from the wellbore. This enables targeted component replacement, significantly reducing downtime compared to replacing the entire drill string assembly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances the durability and operational life of the universal joint by minimizing erosion, providing a compact assembly, and enabling early detection of wear and overstress, thus reducing downtime and operational expenses.
Implementation Method 1
Each member connects to a periphery of a bearing element that flexes to provide relative movement between the members
Implementation Method 2
a ball bearing system for axial load transmission
Data Source
AI summary
A universal joint assembled to a drill string transfers torque between two components where rotation of the components may not be completely aligned. The universal joint includes upper and lower longitudinal members each connected to opposite sides of a bearing element. The elements are connected to the bearing element at spaced radial positions. As the joint rotates the bearing element flexes between the connections to accommodate misalignment of the elements. Axial force can be transferred through the bearing element as well as torque.