Downhole Motor Connecting Rod With Articulating Joint
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Downhole mud motors face challenges in efficiently transferring high torque and axial thrust loads due to the limitations of existing connecting rods, which lead to side loads, bending moments, and potential failures, especially with increased power section torque capacities and smaller diameter constraints.
Innovation Solution
A connecting rod assembly with a housing and a connecting rod that includes a rigid connection to the rotor, a mid flexible rod section, and an articulating joint, where the flexible rod is made from materials like titanium alloys, and the articulating joint is designed to reduce side loads and bending moments through optimized placement and material selection, allowing for efficient torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rigid connecting rod is used to transfer high torque, then torque transfer capability is improved, but side loads and bending moments increase causing potential failures
Solution Approach 1:
The connecting rod is divided into multiple segments: a first connecting rod section rigidly connected to the rotor, a second connecting rod section with articulating joints at both ends, and a third connecting rod section rigidly connected to the drive shaft. This segmentation allows different portions of the connecting rod to perform different functions - the middle section with articulating joints accommodates misalignment and reduces side loads, while the end sections provide rigid torque transfer paths.
Solution Approach 2:
The second connecting rod section with articulating joints acts as an intermediary between the rotor and drive shaft. These articulating joints serve as mediators that accommodate angular misalignment and reduce the transmission of side loads and bending moments from the rigid sections to the rotor and drive shaft, thereby improving reliability while maintaining torque transfer capability.
2Strength
If the connecting rod length is increased to reduce bending moments, then structural integrity is improved, but the motor length and offset increase
Solution Approach 1:
The connecting rod is segmented into three sections with different structural characteristics. The first and third sections can be optimized for strength with appropriate lengths, while the middle section with articulating joints provides flexibility that reduces the need for excessive overall length to accommodate bending moments, thus controlling the total motor length and bit offset.
Solution Approach 2:
The articulating joints in the second connecting rod section change the flexibility parameter of the connecting rod assembly. This allows the system to accommodate angular movements without requiring excessive length, as the articulating joints provide the necessary flexibility to reduce bending moments while maintaining structural integrity over a compact length.
3Reliability
If articulating joints are used to reduce side loads, then reliability is improved, but device complexity increases
Solution Approach 1:
The connecting rod is segmented such that articulating joints are used only in the middle section, while the end sections remain rigid with simpler connections. This selective application of complexity - using articulating joints only where needed to reduce side loads between the rotor and drive shaft - improves reliability without unnecessarily complicating the entire connecting rod assembly.
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 solution effectively reduces side loads and bending moments, enabling the connecting rod to handle peak torques and dynamic changes in rotational speed, while maintaining structural integrity and reducing the length required for torque transfer, thus enhancing the motor's steerability and operational reliability.
Implementation Method 1
a mid flexible rod section connected between the proximal and distal ends of the connecting rod
Data Source
AI summary
A downhole motor may include a power section, a connecting rod assembly, and a drive shaft. The power section may include a stator and a rotor with the rotor configured to rotate eccentrically when a drilling fluid is passed through the stator. The connecting rod assembly operatively connects the rotor of the power section and the drive shaft of the bearing section. The connecting rod assembly may include a housing and a connecting rod. The housing may have a proximal end and a distal end with the proximal end connected to the stator. The connecting rod may include a proximal end including a rigid connection operatively connected to the rotor, a mid flexible rod, and a distal end terminating at or proximate an articulating joint. The drive shaft may be operatively connected to the articulating joint.