Downhole Constant Velocity Joint Inserts for Galling-Resistant Torque Transfer
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Solution Overview
Problem
Traditional universal joints used in downhole power systems for oil and gas drilling suffer from damage due to galling, shear, and compressive forces, which affect the efficient transmission of torque and thrust between rotating components.
Innovation Solution
A constant velocity joint design featuring a drive shaft with radially extending arms and a tubular housing with slots, utilizing inserts made of materials with different galling properties to minimize wear and ensure uniform load transfer, along with a lubrication system using a viscous fluid with nano diamond particles to reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional universal joints utilize ball bearings or meshing gear elements for force transfer, then torque transmission is achieved, but the components suffer from galling, shear and compressive forces causing damage
Solution Approach 1:
The patent changes the contact mechanism from point contact (ball bearings) or line contact (gear elements) to surface contact through axially extending shoulders on the drive shaft engaging corresponding shoulder surfaces in the rotor. This surface contact distribution reduces stress concentration and minimizes galling and compressive forces while maintaining torque transmission capability
Solution Approach 2:
The patent introduces an insert or 'key' at the shoulder surface of the spherically shaped drive shaft end to act as an intermediary element. This insert minimizes direct wear and galling between the drive shaft and rotor surfaces by providing a protective interface that reduces harmful friction and stress
2Reliability
If surface contact universal joints are used with inserts to minimize wear, then torque transmission is improved, but the inserts continue to exhibit damage from galling, shear and compressive forces
Solution Approach 1:
The patent utilizes inserts made of composite materials or materials with specific properties (such as soft inserts or inserts with different galling properties) to enhance wear resistance while maintaining strength. The use of materials like PTFE (Teflon) or other low-friction, high-wear-resistance materials helps the inserts withstand galling, shear and compressive forces without failing
3Power
If drilling mud is pumped through rotor and stator to rotate the rotor, then rotational energy is generated, but friction and wear occur in the universal joint assembly
Solution Approach 1:
The insert acts as a mediator between the drive shaft and rotor surfaces, reducing direct metal-to-metal contact and minimizing friction and wear caused by the high-speed rotation generated by the mud motor
Solution Approach 2:
The patent changes the surface contact parameters by introducing surface treatments, coatings, or material selections that reduce the coefficient of friction and wear, allowing the universal joint to operate efficiently under the continuous rotational forces generated by the drilling mud-powered motor
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 solution effectively reduces galling and damage, ensuring reliable and efficient torque transmission while accommodating omni-directional rotation and axial thrust loads, enhancing the durability and performance of downhole power transmission systems.
Implementation Method 1
a lubrication system using a viscous fluid with nano diamond particles to reduce friction
Data Source
AI summary
A constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.