Steering Joint Universal Joints Torque Lock
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Solution Overview
Problem
Existing steerable drilling systems face challenges such as limited space in horizontal drilling, mechanical torque issues, asymmetric drill heads causing lateral deflection, and inefficient hydraulic motors with pressure unbalance and wear, which complicate drilling small radii and stability of drilled holes.
Innovation Solution
A steering joint with a universal joint connecting upper and lower tubulars, featuring axially protruding cams and radial grooves for positive force-fitting connection, allowing predefined steering angles, and a hydraulic or electric motor-driven step piston with wedged tracks and elastic return for precise orientation control, along with a hydraulic motor design minimizing leakage and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a drill head is rotated to propel through the ground, then drilling capability is improved, but torque lock becomes difficult to achieve with mechanical means
Solution Approach 1:
The patent replaces traditional mechanical torque lock mechanisms with a hydraulic locking system. A hydraulic piston engages with a locking surface on the drill head, providing secure torque transmission without complex mechanical levers or handles. This substitution maintains drilling capability while significantly improving ease of operation, as the hydraulic system can be controlled remotely or automatically.
2Productivity
If a stiff drill string is used to transfer hammering force, then propulsion efficiency is improved, but bending radius of drilled bore is limited
Solution Approach 1:
The patent segments the drill string into multiple articulated sections connected by universal joints. Each section can bend independently, allowing the drill string to navigate tight curves while maintaining structural integrity for force transmission. This segmentation enables both efficient hammering propulsion and the ability to drill small radius bends that would be impossible with a stiff, continuous drill string.
Solution Approach 2:
The patent introduces dynamic flexibility to the drill string through universal joints that allow controlled bending. The drill string transitions from a static, rigid structure to a dynamic, articulated system that can adapt its shape during drilling while maintaining sufficient stiffness for force transmission. This dynamic capability enables navigation of complex bore paths with varying bending radii.
3Adaptability or versatility
If asymmetrically shaped drill heads are used for steering, then steering capability is improved, but lateral deflection occurs when pushed forward without rotation
Solution Approach 1:
The patent introduces a universal joint as an intermediary between the asymmetric drill head and the drill string. The universal joint decouples the steering function from the propulsion function, allowing the asymmetric drill head to steer when needed while preventing unwanted lateral deflection during straight drilling. The joint acts as a mediator that transmits force axially while isolating the asymmetric geometry from causing lateral instability.
4Power
If hydraulic motors with offset rotational center are used, then drilling power is improved, but pressure unbalance and wear increase
Solution Approach 1:
The patent employs an asymmetric cam profile in the hydraulic motor design that compensates for the offset rotational center. The cam geometry is specifically shaped to distribute hydraulic pressure more evenly throughout the rotation cycle, reducing peak pressures and minimizing unbalance forces. This asymmetric design maintains high drilling power while improving reliability by reducing wear on the cam and follower components.
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
Enables precise steering and torque control, reduces mechanical complexity, and enhances drilling stability and efficiency, particularly in tight spaces, by allowing stepwise rotation and axial movement for flexible drilling orientations and reduced wear on components.
Implementation Method 1
The cams and the grooves are arranged in such a way to provide a positive force-fitting connection of the bearing socket with the step piston
Implementation Method 2
a hydraulic or electric motor-driven step piston with wedged tracks and elastic return for precise orientation control
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3h
AI summary
The invention relates to a steering joint (3) for a steerable drilling system, comprising an upper tubular (301) and a lower tubular (302) connected by a universal joint (303) which allows the upper tubular (301) to bend with respect to the lower tubular (302), wherein the universal joint (303) comprises a joint bearing socket (306) with a hollow core, comprising axially protruding cams (311) with identical extension on a substantially ringshaped face end, a cylindrical and rotatable step piston (308) with a hollow core and radial grooves (312) on a substantially ring-shaped face end, wherein the cams (311) and the grooves (312) are arranged in such a way to provide a positive force-fitting connection of the bearing socket (306) with the step piston (308), and wherein the grooves (312) are of different depth and their bases define inclined planes with respect to the plane of the face end of the step piston (308), so that the upper tubular (301) and the lower tubular (302) can be tilted with respect to each other at predefined steering angles. The invention further relates to the use of such a steering joint in a drilling system, and a drilling system with such a steering joint.