Universal Joint Assembly With Flat Torque Faces for Wear Reduction
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Solution Overview
Problem
Down-hole mud motor universal joint assemblies face issues with excessive wear and failure due to the rubbing action of torque-transmitting balls or barrel rollers within dimples, leading to radial force distortion, vibration, and torque backlash, as well as the need for multiple U-joints which increases component failure chances.
Innovation Solution
A universal joint assembly design featuring a female U-joint member with a cavity and flat surfaces and a male U-joint member with multi-angled surfaces, allowing for near-constant face-to-face contact and distributing torque across a substantial surface area, reducing wear and eliminating the need for multiple U-joints by using a single U-joint assembly with a flexible shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If torque-transmitting balls or barrel rollers are used within dimples, then positive coupling between joint members is achieved, but excessive wear and radial force distortion occur
Solution Approach 1:
The torque transmission function is segmented from the ball/roller elements to the flat surface contact interfaces. The male U-joint member has a drive end with flat surfaces and the female U-joint member has a receptacle end with flat surfaces, creating distributed contact areas that replace the concentrated point contact of balls/rollers, thereby reducing wear while maintaining torque transmission
Solution Approach 2:
The problematic ball and barrel roller elements are extracted from the joint assembly. The invention eliminates these intermediate torque-transmitting elements entirely, using direct flat surface contact between the male and female U-joint members instead, which removes the source of rubbing action and wear
2Adaptability or versatility
If multiple U-joints are used to accommodate articulating joints, then torque transmission across angular connections is achieved, but component failure probability increases
Solution Approach 1:
The U-joint assembly is designed to perform multiple functions: it can accommodate angular connections between shafts, transmit torque efficiently, and compensate for misalignment. The flat surface contact mechanism and articulation capability are integrated into a single universal design that can handle various angular configurations without requiring multiple separate joints
Solution Approach 2:
Multiple U-joint functions are merged into a single integrated assembly. The male and female U-joint members form a unified torque transmission system that combines angular accommodation, torque transmission, and wear resistance in one component package, eliminating the need for multiple separate joints and reducing overall system failure probability
3Power
If balls and barrel rollers rotate within dimples, then torque is transmitted between joint members, but rubbing action causes excessive wear
Solution Approach 1:
The contact interface transitions from static point contact (balls/rollers in dimples) to dynamic flat surface contact. The flat surfaces on the male and female members maintain near-constant face-to-face contact during articulation, allowing torque transmission through sliding friction rather than rolling friction, which reduces wear on the contact surfaces
Solution Approach 2:
The contact geometry parameters are changed from spherical/cylindrical elements with small contact areas to flat surfaces with large contact areas. This parameter change increases the surface area over which torque is distributed, reducing contact pressure and wear rate while maintaining the same torque transmission capability
Data Source
AI summary
A transmission assembly includes a cavity in a female U-joint having a groove that extends radially outward from an inner diameter thereof and bounded by three planar drive surfaces. A male U-joint member includes a drive end includes a longitudinal rectangular extension protruding radially outward from a periphery and positioned within the groove of the cavity. The drive end includes a longitudinal rectangular insert has a portion forming the extension positioned within the groove and retained within the drive end. The extension includes (1) opposing longitudinal sides, each forming a side crest disposed between a pair of angular side surfaces that extend axially from the side crest inward toward a center of the extension, and (2) a top side forming a top crest disposed between a pair of angular top surfaces that extend axially from the top crest downward toward the center of the extension.