Unitary Mud Motor Stator Housing Eliminates Threaded Connections
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Solution Overview
Problem
Mud motors experience premature fatigue failures due to high cyclical loads and stress at threaded connections, particularly in high dogleg severity conditions, leading to unserviceable motors and increased servicing costs.
Innovation Solution
The implementation of a continuously formed power section stator housing with a unitary combination of stator lobes and transition portion, eliminating threaded connections and incorporating a preassembled rotor assembly with roller-type bearings, which is welded to form a single integral piece, reducing fatigue failure sources and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If threaded connections are used in the power section stator housing, then the housing can be assembled from separate parts, but fatigue failures occur at the threaded connections under high cyclical loads
Solution Approach 1:
The patent merges the previously separate power section stator housing parts into a single continuously formed unitary housing. This eliminates the threaded connections that were causing fatigue failures, while still allowing the housing to be manufactured in sections and joined by welding. The unitary structure removes the stress concentration points at threaded interfaces, directly resolving the reliability issue.
Solution Approach 2:
The patent segments the housing into a drillable section and a non-drillable section, which are continuously formed as a unitary structure. This segmentation allows different portions of the housing to be optimized for their specific functions while maintaining structural integrity throughout, eliminating the need for threaded connections between critical stress areas.
2Reliability
If threaded connections are eliminated and a continuously formed housing is used, then fatigue failures are reduced, but manufacturing complexity increases
Solution Approach 1:
The housing is segmented into drillable and non-drillable sections that are continuously formed together. This segmentation simplifies the manufacturing process by allowing each section to be formed with optimized processes while maintaining the benefits of a unitary structure that eliminates threaded connections.
Solution Approach 2:
The transition portion acts as an intermediary between the drillable and non-drillable sections, providing a smooth continuous transition that eliminates stress concentrations. This intermediary structure allows the housing to be formed continuously without requiring complex threaded connections or assembly steps.
3Reliability
If a unitary combination of stator lobes and transition portion is used, then fatigue failure sources are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The stator lobes and transition portion are formed as a unitary combination in a single continuous forming operation, eliminating the need for separate machining and assembly operations. This segmentation into functional zones formed simultaneously reduces the accumulation of tolerances and eliminates the stress concentrations that would arise from joining separate components.
Data Source
AI summary
A mud motor, system, and method for using same are disclosed. A mud motor can include a continuously formed power section stator housing having a first end, a second end, and an internal cavity comprising a series of stator lobes and a housing portion passing. The stator lobes can extend from the first end of the power section stator housing until a first end of a transition portion. The transition portion can form a unitary combination with the stator lobes. The mud motor further includes a rotor assembly including a power section rotor having rotor lobes to be disposed completely within the internal cavity. Additional apparatuses, systems, and methods are disclosed.