Radial Support in Stator Housing for Downhole Motor
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Solution Overview
Problem
The high stress loads on the stator caused by the eccentric rotation of the rotor in downhole drilling motors lead to fatigue of the elastomeric stator contour, particularly at the lower end of the power section, due to the increased horse power and rotor mass.
Innovation Solution
A radial support is integrated with the stator contour, extending axially from the downhole end of the stator housing, which provides physical support between the stator housing and the rotor and transmission components, reducing radial movement and stress on the stator contour, and is manufactured and serviced efficiently as part of the stator contour formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor mass and eccentricity are increased to provide higher power output, then the power output increases, but the stress loads on the stator contour increase causing fatigue
Solution Approach 1:
The stator contour is segmented into multiple sections: an upper section, a lower section, and a radial support section. The radial support section is positioned at the lower end where fatigue occurs and provides localized reinforcement to distribute and reduce stress concentrations, allowing the stator to withstand higher power outputs without compromising overall strength
Solution Approach 2:
The radial support section is formed from a composite material or structure that combines the elastomeric properties of the stator contour with enhanced mechanical strength. This composite construction allows the radial support to resist fatigue from high stress loads while maintaining the necessary flexibility for rotor support
2Power
If the rotor mass is increased to provide higher power output, then the power output increases, but the radial movement and stress on the stator contour increase
Solution Approach 1:
The radial support section is pre-positioned at the lower end of the stator contour where stress concentrations occur during rotor rotation. This preliminary placement of support structure prevents stress from concentrating on the stator contour during operation, allowing the system to handle increased rotor mass and power output
3Power
If the stator contour is designed to accommodate heavy rotor mass and high eccentricity, then power output increases, but the lifespan of the stator contour decreases due to fatigue
Solution Approach 1:
By segmenting the stator contour into distinct sections including a dedicated radial support section at the lower end, the design isolates the area most susceptible to fatigue. This segmentation allows the radial support to bear the brunt of cyclic stresses from heavy rotor mass and high eccentricity, protecting the main stator contour and extending its lifespan while maintaining high power output capability
Solution Approach 2:
The radial support section acts as an intermediary element between the rotor and the main stator contour. It absorbs and distributes the cyclic stress loads generated by rotor rotation, preventing direct transmission of fatigue-inducing stresses to the main stator contour, thereby extending the stator's service life under high power conditions
Data Source
AI summary
A system for providing support in a downhole motor, the system includes a stator housing including an end, a stator contour within the stator housing, a rotor including a rotor end and lobes configured to engage with the stator contour to eccentrically rotate the rotor, and a radial support extending from the stator contour toward the end of the stator housing, and positioned radially between the rotor end of the rotor and the stator housing to support the rotor and decrease an amount of eccentric rotation of the rotor.