PDD Motor Assembly for BOP Ram Actuation
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Solution Overview
Problem
Existing blowout preventer (BOP) systems rely on hydraulic cylinders for actuating rams, which can lead to manufacturing complexity, cost, and operational reliability issues due to the need for hydraulic lines, fluid reservoirs, and pumps, and lack precise control over ram positions during sealing and shearing operations.
Innovation Solution
The implementation of pseudo direct drive (PDD) motor assemblies with integral magnetic gearing, which actuate rams between default and engaged positions without hydraulic cylinders, utilizing encoders for precise position monitoring and control, and motion conversion mechanisms to convert rotational motion into longitudinal movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If hydraulic cylinders are used to actuate rams, then the BOP system can achieve sufficient force for sealing and shearing operations, but the manufacturing complexity and cost increase due to hydraulic lines, fluid reservoirs, and pumps
Solution Approach 1:
The patent extracts and removes the hydraulic system components (hydraulic lines, fluid reservoirs, pumps, hydraulic cylinders) from the BOP actuation system. Instead, it implements a rotary actuator with a screw mechanism that converts rotational motion directly into linear motion of the rams, eliminating the need for complex hydraulic infrastructure while maintaining sufficient actuation force for sealing and shearing operations
Solution Approach 2:
The patent replaces the hydraulic mechanical system with a rotary actuator and screw mechanism system. The rotary actuator drives a screw that engages with a nut or threaded rod, converting rotational motion into linear motion to actuate the rams. This mechanical substitution eliminates hydraulic fluid requirements and associated components while providing precise control and sufficient force
2Ease of operation
If hydraulic cylinders are used for ram actuation, then the system can operate with simple control mechanisms, but the operational reliability decreases due to potential hydraulic line failures and fluid leaks
Solution Approach 1:
The patent removes hydraulic lines and fluid reservoirs from the system, eliminating potential failure points associated with hydraulic fluid leaks, line ruptures, and contamination. The closed-loop electrical control system with position feedback provides reliable operation without the inherent vulnerabilities of hydraulic systems
Solution Approach 2:
The patent implements feedback control through position sensors (such as encoders or linear variable differential transformers) that monitor the actual position of the rams and provide feedback to the control system. This closed-loop control enhances reliability by enabling real-time adjustments and detection of abnormal conditions, ensuring precise and reliable ram actuation
3Device complexity
If traditional actuation systems are used, then the BOP system can maintain simple structure, but the manufacturing cost increases due to specialized hydraulic components
Solution Approach 1:
The rotary actuator with screw mechanism serves multiple functions: it provides linear actuation force, enables precise position control, and can be integrated with position feedback sensors. This multi-functional component replaces multiple specialized hydraulic components (cylinders, valves, pumps, reservoirs), reducing overall system complexity and manufacturing cost while maintaining actuation capability
Solution Approach 2:
The patent replaces expensive, specialized hydraulic components with more universally available rotary actuators and screw mechanisms. These components are typically easier to manufacture, source, and maintain, reducing overall manufacturing costs while providing equivalent or superior performance in terms of control precision and reliability
4Manufacturing precision
If hydraulic cylinders are used for ram actuation, then the system can achieve adequate positioning, but the precision control of ram positions during sealing and shearing operations is insufficient
Solution Approach 1:
The patent implements feedback control through position sensors that continuously monitor the actual position of the rams and provide real-time feedback to the control system. This closed-loop control enables precise positioning during sealing and shearing operations by comparing the desired position with the actual position and making corrective adjustments, achieving high manufacturing precision without requiring overly complex mechanical structures
Solution Approach 2:
The patent replaces the hydraulic cylinder positioning mechanism with a rotary actuator and screw mechanism combined with electronic position feedback. This substitution enables more precise control because the screw mechanism provides inherent mechanical advantage and the electronic feedback system can detect and correct position deviations with high accuracy, achieving superior positioning precision compared to traditional hydraulic systems
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 manufacturing costs and complexity, enhances operational reliability by eliminating hydraulic components and enabling precise control of ram positions, improving the overall performance of the BOP system during sealing and shearing operations.
Implementation Method 1
a motor configured to convert a supply of electrical power into a rotational output at an output shaft
Implementation Method 2
a screw mechanism configured to convert rotation of the output shaft into longitudinal movement of a piston
Data Source
AI summary
The present disclosure relates to a drive system for a blowout preventer (BOP). The drive system includes a first pseudo direct drive (PDD) motor assembly having a first PDD motor and a second PDD motor assembly having a second PDD motor. The first PDD motor is configured to engage with a first shaft coupled to a first ram of the BOP and the second PDD motor is configured to engage with a second shaft coupled to a second ram of the BOP. The first PDD motor and the second PDD motor are operable to induce translation of the first shaft and the second shaft, respectively, to drive the first ram and the second ram toward one another along a longitudinal axis to reach an engaged configuration in the BOP.