Universal Joint Floating Washer Sealing and Lubrication
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Solution Overview
Problem
Downhole drilling motors, particularly moineau-style motors, face premature failure due to loss of lubrication and joint misalignment, which can lead to eccentric rotation issues and increased friction, causing wear and tear on components.
Innovation Solution
A universal joint assembly with a rotatable mandrel, spherical drive balls, and a floating washer, along with a lubricating system that includes a reservoir and pressure-balanced lubricant piston, maintains constant lubrication and seals drilling fluid from the lubricating fluid, allowing for up to 4 degrees of bend without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the mandrel rotates within the cavity allowing eccentric motion transfer, then power is transferred from eccentric to concentric rotation, but misalignment and friction increase causing wear
Solution Approach 1:
The patent applies lubricant to the mandrel and drive balls before operation begins. The lubricant is delivered through channels in the housing to the joint interface, pre-lubricating components to minimize friction and wear from the start of operation, thereby reducing component wear while maintaining power transfer capability.
Solution Approach 2:
The patent provides continuous lubrication to the universal joint components during operation. Lubricant is continuously supplied through channels in the housing to the mandrel and drive balls, ensuring uninterrupted lubrication that reduces friction and wear throughout the power transfer process, improving reliability.
2Temperature
If drilling fluid is pumped through the drill string to cool and lubricate components, then cooling and lubrication are provided, but drilling fluid contaminates the lubricating medium
Solution Approach 1:
The patent segments the lubrication system from the drilling fluid flow path. The housing contains internal lubricant channels that are sealed off from the external drilling fluid environment using radial seals. This segmentation allows the lubricating medium to remain pure and uncontaminated while still providing cooling and lubrication to internal components.
Solution Approach 2:
The patent uses radial seals (O-rings) as intermediary barriers between the drilling fluid and lubricating medium. These seals allow the system to maintain separate fluid zones, preventing contamination of the lubricant while still enabling thermal management through the housing structure.
3Adaptability or versatility
If the universal joint allows up to 4 degrees of bend, then adaptability to well bore angles is improved, but misalignment increases causing increased friction and wear
Solution Approach 1:
The patent pre-lubricates the universal joint components before operation, ensuring that lubricant is present at the joint interface from the start. This preliminary lubrication reduces friction and wear even when the joint operates at maximum 4-degree bend angles, improving component durability while maintaining adaptability.
Solution Approach 2:
The patent provides continuous lubrication to the universal joint components during operation at various bend angles. The internal lubricant channels continuously supply lubricant to the mandrel and drive balls, ensuring that friction and wear are minimized throughout the full range of 4-degree motion, thereby improving component durability.
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 universal joint assembly enhances the durability and efficiency of downhole drilling operations by maintaining a seal between lubricating and drilling fluids, reducing wear, and providing consistent lubrication proportional to drilling pressure, thus extending the life of drilling components.
Implementation Method 1
The floating washer is disposed within the substantially circular groove and configured to radially displace within the groove when the central axis of the mandrel is displaced from a central axis of the assembly housing
Implementation Method 2
The lubricant piston may include an interior surface, where a first pressure is applied to the interior surface, and an exterior surface. A second pressure may be applied to the exterior surface. The lubricant piston may drive the lubricating fluid from the reservoir to the cavity when the second pressure is greater than the first pressure.
Implementation Method 3
The plurality of substantially spherical drive balls are rotatable within the cavity about a central axis of the mandrel
Implementation Method 4
The ring seal may be disposed between the floating washer and the mandrel and in contact with the mandrel and the washer during rotation of the mandrel within the cavity
Data Source
AI summary
A universal joint assembly includes an assembly housing, an assembly cap coupled to the assembly housing, a rotatable mandrel, a plurality of substantially spherical drive balls, and a floating washer. The assembly housing has a plurality of pockets formed in an interior surface of the assembly housing. The rotatable mandrel is fitted within a cavity defined by the assembly housing and the assembly cap and has a plurality of pockets configured to partially receive the drive balls. The substantially spherical drive balls are rotatable within the cavity about a central axis of the mandrel. A substantially circular groove formed in the cavity is defined by a proximal end of the assembly cap and an interior wall and a shoulder of the assembly housing. The floating washer is disposed within the substantially circular groove and configured to radially displace within the groove.