Locking Clutch With Centrifugal Pawls for Downhole Motors
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Solution Overview
Problem
Downhole motors, particularly turbine mud motors, struggle to prevent drill bits from becoming stuck in formations and lack sufficient torque to free stuck bits without requiring manipulation of the drill string or fluid flow rate.
Innovation Solution
A locking clutch mechanism with locking pawls that biases into an engaged position to transmit torque from the stator to the rotor when the drill bit becomes stuck, disengaging when the rotor speed exceeds a certain threshold to prevent wear and allow normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking clutch mechanism is added to prevent drill bits from becoming stuck, then reliability is improved, but device complexity increases
Solution Approach 1:
The locking clutch mechanism is designed to automatically engage and disengage based on rotational speed conditions without requiring external control systems. The centrifugal force generated by rotor rotation naturally actuates the locking and unlocking actions, making the system self-regulating and eliminating the need for complex control mechanisms.
Solution Approach 2:
The patent introduces a centrifugal intermediary mechanism that mediates between the rotor's rotational speed and the locking clutch engagement. This intermediary uses centrifugal force as a natural physical mediator to translate rotational speed into mechanical engagement/disengagement actions, simplifying the overall control architecture.
2Reliability
If torque is continuously applied to prevent sticking, then reliability is improved, but wear increases
Solution Approach 1:
The locking clutch operates periodically rather than continuously, engaging only when rotational speed drops below the threshold and disengaging when speed exceeds the threshold. This periodic operation pattern eliminates continuous wear while maintaining reliability during critical low-speed conditions.
Solution Approach 2:
The system transitions from a static locking mechanism to a dynamic one that adapts its engagement state based on real-time rotational speed conditions. The locking clutch automatically adjusts its state (engaged or disengaged) according to the rotor's speed, providing torque only when necessary and reducing wear during normal high-speed operation.
3Ease of operation
If manual intervention is required to free stuck bits, then ease of operation is maintained, but loss of time increases
Solution Approach 1:
The locking clutch mechanism automatically frees stuck drill bits by engaging when rotational speed drops and disengaging when speed increases, eliminating the need for manual intervention. The system self-diagnoses and self-corrects sticking conditions, saving significant time while maintaining operational simplicity.
4Reliability
If the locking clutch remains engaged to prevent sticking, then reliability is improved, but wear increases
Solution Approach 1:
The locking clutch engages periodically only when rotational speed falls below the threshold indicating potential sticking, and disengages when speed exceeds the threshold indicating normal operation. This periodic engagement pattern provides continuous protection when needed while minimizing wear during normal high-speed drilling operations.
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
The locking clutch effectively prevents drill bits from becoming stuck and facilitates their release by applying torque from the drillstring to the stator and rotor, disengaging automatically when the drill bit resumes higher rotational speed, reducing the risk of wear and eliminating the need for surface intervention.
Implementation Method 1
centrifugal force rotates the at least one locking pawl from the engaged position to the disengaged position when the speed of the rotor exceeds a certain threshold
Implementation Method 2
a biasing mechanism rotates the at least one locking pawl from the disengaged position to the engaged position
Data Source
AI summary
A locking clutch to selectively transmit torque from a stator of a downhole tool to a rotor of the downhole tool includes at least one locking pawl disposed upon the rotor. The at least one locking pawl comprises a load path, a pivot axis, and a mass center, and is biased into an engaged position by a biasing mechanism. The at least one locking pawl transmits force from the stator to the rotor along the load path when in the engaged position, and centrifugal force urges the at least one locking pawl into a disengaged position when the rotor is rotated above a disengagement speed.