Radiused Conical Bearing Assembly for Offset Drill Shafts
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Solution Overview
Problem
Existing bearing assemblies for directional drilling face challenges in maintaining efficient rotation and reducing wobble and stress on the drill string while achieving desired angular offsets, leading to potential damage to the wellbore and increased power consumption.
Innovation Solution
The offset shaft bearing assembly incorporates radiused conical bearings that allow for relative rotation between the drive shaft and outer housing, enabling angular misalignment while resisting thrust and radial loading, and includes features like external stabilizers and a bent housing to achieve precise angular control and reduced eccentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bearing assemblies are used to support the drive shaft, then the structure is simple and easy to manufacture, but the rotation efficiency is poor, wobble and stress on the drill string increase, and power consumption increases
Solution Approach 1:
The patent employs radiused conical bearings with curved raceways instead of straight linear bearings. The radiused (curved) contact surfaces allow for smoother rotation and better accommodation of angular misalignment between the drive shaft and housing, reducing friction and wobble during high-speed rotation, thereby improving rotation efficiency and reducing power consumption.
Solution Approach 2:
The patent changes the geometric parameters of the bearing assembly by introducing conical shapes with specific radii of curvature. The radiused conical bearings have optimized curvature radii that allow for efficient rotation while accommodating angular offsets, transforming the bearing geometry to achieve both high-speed rotation capability and reduced energy consumption.
2Stability of the object's composition
If the drive shaft is aligned concentrically with the housing, then the structure is simple, but angular misalignment cannot be accommodated and wobble increases
Solution Approach 1:
The patent introduces asymmetric conical bearing geometries with radiused surfaces that are specifically shaped to accommodate angular misalignment. The conical shape with optimized radius allows the bearing to handle offset angles between the drive shaft and housing while maintaining rotational stability, transforming the symmetric concentric alignment into an asymmetric configuration that better suits directional drilling requirements.
3Productivity
If high-speed rotation is achieved, then drilling productivity increases, but wobble and stress on the drill string increase causing potential damage
Solution Approach 1:
The radiused conical bearings with curved raceways provide smoother rotation at high speeds by distributing contact stresses more evenly and reducing wobble. The curvature allows for better accommodation of dynamic loads and angular misalignment during high-speed operation, enabling increased drilling productivity while minimizing harmful wobble and stress on the drill string.
Solution Approach 2:
The radiused surfaces of the conical bearings act as a cushioning mechanism that anticipates and accommodates angular misalignment and dynamic loads before they cause harmful effects. The curved geometry provides a buffer that reduces shock and wobble during high-speed rotation, protecting the drill string from damage while maintaining high drilling speeds.
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
This solution enables reliable high-speed rotation with reduced wobble and stress, allowing for efficient directional drilling with lower power consumption and minimized damage to the wellbore and drill string, while maintaining precise angular control and build direction.
Implementation Method 1
The bearing section may include first and second radiused conical bearings positioned about the drive shaft
Implementation Method 2
The bearing section couples to the drive shaft through one or more bearings to allow rotation of the drive shaft
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An offset shaft bearing assembly includes a drive shaft extending through an outer housing. The drive shaft centerline is at an angle to the centerline of the outer housing. The shaft is coupled to the outer housing by radiused conical bearings which act as thrust and radial bearings. At least one of the radiused conical bearings is offset from the centerline of the outer housing. The radiused conical bearings may include a curved bearing surface, allowing the radiused conical bearings to operate despite angular misalignment.