Polygonal Flexible Coupling for High-Torque Misaligned Shafts
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Solution Overview
Problem
Traditional torque transmission systems in downhole drilling, such as Knuckle Joints and Universal Ball Joints, are prone to failure due to high vibrations, abrasive wear, and limited torque capacity, leading to reduced drilling efficiency and increased maintenance costs.
Innovation Solution
The Hex Drive system uses a polygonal design with wear plates and a spherical pivot point to distribute torque loads evenly, reducing vibrations and allowing for greater torque transmission while maintaining alignment flexibility, and incorporates a unique seal assembly to prevent mud invasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional Knuckle Joints or Universal Ball Joints are used for torque transmission, then alignment flexibility is provided, but torque capacity is limited and component failure occurs due to high vibrations and abrasive wear
Solution Approach 1:
The coupling is divided into multiple segments including a first component, second component, and intermediate member with distinct functional zones. The intermediate member contains a plurality of elements arranged in a circle that can independently deform to accommodate misalignment while distributing torque across multiple contact points, preventing single-point failure and reducing vibrational stresses.
Solution Approach 2:
The intermediate member is constructed from elastomeric material providing flexibility and vibration damping, while incorporating metallic or hardened elements for torque transmission. This composite construction combines the advantages of flexible materials (vibration absorption, misalignment accommodation) with rigid materials (torque capacity, wear resistance) to simultaneously improve strength and reliability.
2Strength
If rigid coupling designs are used to increase torque capacity, then strength is improved, but misalignment accommodation and alignment flexibility are lost
Solution Approach 1:
The intermediate member is designed as a dynamic element that can deform elastically in response to misalignment and vibrational forces. The elastomeric material allows the coupling to adapt its shape and position dynamically during operation, maintaining torque transmission capability while accommodating varying degrees of misalignment and absorbing shock loads.
Solution Approach 2:
The coupling design changes the physical state and properties of the intermediate member by using elastomeric material with specific durometer ratings and cross-sectional geometries. These parameter changes enable the intermediate member to provide both flexibility for misalignment accommodation and sufficient rigidity for torque transmission, resolving the contradiction between strength and adaptability.
3Power
If downhole couplings are designed for high torque transmission, then power transmission capability is improved, but vibration and abrasive wear increase leading to reduced lifespan
Solution Approach 1:
The elastomeric intermediate member acts as a cushioning element that absorbs and dampens vibrational forces and shock loads before they can cause damage to the coupling components or drill string. This beforehand cushioning protects the mechanical elements from high-stress conditions, reducing wear and extending component lifespan while maintaining high torque transmission capability.
Solution Approach 2:
The design converts the harmful effects of vibration and misalignment into beneficial functions by using the elastomeric material's natural damping properties and elastic deformation capability. The vibrations that would normally cause wear are instead absorbed and dissipated as heat in the elastomeric intermediate member, while misalignment is converted into elastic deformation that maintains continuous contact and torque transmission.
Data Source
AI summary
The present invention comprises a flexible coupling device, system and method for transferring high torque loads and complex rotary motion between components or devices. Specifically, high torque loads and complex rotary motions are transmitted from a motor, through and to an input shaft and to an output shaft, by way of a polygonal-shaped, flexible coupling, wherein one component or device may be misaligned with the input shaft. The flexible coupling consists of a reciprocating polygonal ball and socket design exhibiting a spherical, convex cap component made to provide variations and adjustments in alignment though a pivot point where rectangular, flat wear plates are utilized to evenly distribute received weight and elastomeric seals about the neck of the polygonal ball seal functionally sensitive components within a lubricating chamber.