Down-Hole U-Joint Assembly With Flat Torque-Transfer Surfaces
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Solution Overview
Problem
Existing down-hole mud motor universal joint assemblies suffer from 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, and require multiple U-joints which increase the risk of component failure.
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 that maintain near-constant contact, distributing torque across a substantial surface area to reduce wear, and optionally using a central ball seat and flexible shaft to transmit torque through angled connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If torque-transmitting balls or barrel rollers are held within dimples in prior art U-joints, then positive coupling between joint members is achieved, but excessive wear and radial force distortion occur due to rubbing action
Solution Approach 1:
The invention extracts the torque-transmitting elements (balls or barrel rollers) from the constrained dimple configuration and replaces them with flat surfaces that maintain positive coupling without the harmful rubbing action. The flat surfaces are positioned to engage directly with corresponding flat surfaces on the mating joint member, eliminating the need for dimples and the associated wear problems.
Solution Approach 2:
Instead of using curved surfaces (balls/rollers in dimples) to transmit torque, the invention inverts the approach by using flat surfaces that engage in a plane. This inversion of the contact geometry transforms the rubbing action into a sliding or rolling contact that maintains positive coupling without the wedge effect that causes radial force distortion and wear.
2Adaptability or versatility
If multiple U-joints are used in down-hole mud motors, then torque transmission across angled connections is achieved, but the risk of component failure increases
Solution Approach 1:
The invention merges the functions of multiple U-joints into a single integrated universal joint assembly. The design incorporates both the male and female joint members with flat surfaces in one assembly, eliminating the need for separate U-joints connected by a common shaft. This reduction in component count directly reduces the number of potential failure points while maintaining the ability to transmit torque across angled connections.
3Power
If balls and barrel rollers rotate with respect to dimple surfaces during joint articulation, then torque is transmitted between joint members, but excessive wear damages the joint
Solution Approach 1:
The invention removes the dimple configuration that causes the rubbing action and replaces it with flat surfaces. The torque-transmitting elements are extracted from the harmful dimple environment and replaced with flat surface geometry that maintains positive coupling without the wedge effect and rubbing action that lead to excessive wear and shortened joint service life.
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 minimizes wear and extends the life of the joint by distributing torque across a large surface area, reducing the need for multiple U-joints and allowing operation in hostile drilling environments with minimal lubrication, thereby enhancing reliability and reducing maintenance costs.
Implementation Method 1
The flat surfaces extending longitudinally from the cavity at 90-degree intervals about an inner diameter of the cavity... each of the multi-angled surfaces of the drive end of the male U-joint member opposes a corresponding one of the four flat surfaces of the female U-joint member
Data Source
AI summary
A universal joint (U-joint) assembly transmits torque from a drive component to a driven component across an articulating joint. The U-joint assembly includes male and female U-joint members, a central ball joint, and a retaining device configured to secure the assembly in an assembled configuration. The female U-joint member includes a cavity extending into a receptacle end thereof. The cavity terminates in a circular receptacle and includes a plurality of rectangular channels extending radially outward from the cavity at equal intervals, each channel defined by three planar drive surfaces. The male U-joint member has a drive end with a plurality of corresponding rectangular extensions protruding from an outer periphery of the drive end, each extension including a plurality of axial angular surfaces. When assembled, each of the angular surfaces of the drive end opposes a corresponding one of the drive surfaces of the cavity. Other embodiments are also disclosed.