Downhole Motor Thrust Bearings Without Pre-Loading
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Solution Overview
Problem
Existing downhole motor designs require compressive pre-loading of thrust bearings, leading to excessive wear and issues with temperature changes, and often necessitate a full-length drive shaft to accommodate eccentric motion, which can be cumbersome and prone to wear.
Innovation Solution
The design incorporates primary and secondary thrust bearings maintained by structural components within the motor housing without compressive loading, utilizing multi-part sectional flex joints to convert eccentric forces into mandrel rotation, allowing for a shorter flex shaft and eliminating the need for pre-loading, thus protecting the bearings from debris and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If compressive pre-loading is applied to thrust bearings, then the bearings can sustain thrust loads, but excessive wear and temperature issues occur
Solution Approach 1:
Instead of pre-compressing the thrust bearings to sustain loads, the invention inverts the approach by allowing the bearings to operate without pre-loading. The bearing assembly design enables the thrust bearings to sustain loads dynamically during operation without requiring initial compressive pre-loading, thereby reducing wear and temperature issues while maintaining load-bearing capability.
Solution Approach 2:
The bearing assembly is designed to automatically adjust and sustain thrust loads during operation without external pre-loading. The structural components and bearing arrangement enable the system to self-regulate and maintain proper bearing function dynamically as loads are applied during motor operation, eliminating the need for manual pre-compression.
2Ease of operation
If a full-length drive shaft is used to accommodate eccentric motion, then rotational power can be transmitted, but the system becomes cumbersome and prone to wear
Solution Approach 1:
The drive shaft is divided into multiple modular sections that can be assembled in different configurations. This segmentation allows the drive shaft to accommodate eccentric motion through proper section arrangement rather than requiring a single long flexible shaft, reducing overall complexity and wear while maintaining the ability to handle eccentricities.
Solution Approach 2:
Instead of solving eccentric motion accommodation by increasing drive shaft length and flexibility in one dimension, the invention addresses the problem by arranging drive shaft sections in specific spatial configurations. The modular sections can be positioned to naturally compensate for eccentricities through their geometric arrangement, reducing the need for excessive length or flexibility in any single dimension.
3Reliability
If thrust bearings are positioned inside the motor housing, then they are protected from debris, but access for pre-loading becomes more difficult
Solution Approach 1:
The bearing assembly is segmented into modular components that can be assembled and pre-loaded as separate units before being installed as a complete assembly into the motor housing. This segmentation allows pre-loading to be performed externally where access is easier, then the entire pre-loaded assembly is installed as one unit, maintaining bearing protection while simplifying the pre-loading process.
Solution Approach 2:
The thrust bearings are pre-loaded and assembled into the bearing assembly structure before the entire assembly is installed into the motor housing. This preliminary action of pre-loading occurs during assembly when access is easier, and the pre-loaded assembly is then installed as a complete unit, ensuring both bearing protection and ease of pre-loading.
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 reduces wear and maintenance needs, allows for a shorter drive shaft, and protects the bearings from debris, enhancing the operational efficiency and longevity of downhole motors by eliminating the need for pre-loading and accommodating eccentricities effectively.
Implementation Method 1
a drive train that features at least one multi-part sectional flex joint may allow for a shortened flex shaft while sufficiently converting eccentric forces from the power source to rotation of the mandrel
Implementation Method 2
Thrust bearings are positioned within the housing to sustain loads tending to force the mandrel axially out the lower end of the housing
Implementation Method 3
Radial bearings are positioned within the housing, between the housing and the mandrel, to take up the radial loads
Data Source
AI summary
The present disclosure is directed to improved downhole motor designs. In one illustrative embodiment, primary and secondary thrust bearings that are maintained in position by other structural components of the motor without compressive loading of the entire bearing assembly are positioned inside the motor housing for protection from cuttings and debris in the drilling fluid. In some illustrative embodiments, a drive train that features at least one multi-part sectional flex joint may allow for a shortened flex shaft while sufficiently converting eccentric forces from the power source to rotation of the mandrel.