Variable Torque Flapper Valve Spring Geometry
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Solution Overview
Problem
Conventional subsurface safety valves, such as flapper valves, face challenges in maintaining effective closure and opening mechanisms due to the need for clearance near the pivot pin, which can compromise the size and strength of the hinge pin and surrounding elements, affecting their performance in oil and gas well operations.
Innovation Solution
The use of a beam spring with a unique dual-arm geometry and c-shape configuration that allows for variable torque and reduced interference with the operator tube, enabling the flapper plate to open completely without overstressing and maintaining a strong, sand-resistant design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clearance is provided near the pivot pin to allow torsion spring positioning, then the torsion spring can be positioned about the pivot pin, but the size of the hinge pin and surrounding elements is reduced
Solution Approach 1:
The patent extracts the spring positioning function from the pivot pin area by introducing a separate spring support surface on the flapper plate. This allows the torsion spring to be positioned without requiring clearance near the pivot pin, thereby maintaining the hinge pin size and strength while still enabling spring installation.
Solution Approach 2:
The patent introduces a spring support surface as an intermediary element between the torsion spring and the flapper plate. This support surface serves as a dedicated mounting location for the spring, eliminating the need for the pivot pin area to accommodate spring clearance requirements.
2Productivity
If the flapper plate is designed to open completely under high pressure, then the valve opening is improved, but the spring and plate may be overstressed
Solution Approach 1:
The patent changes the geometric parameters of the flapper plate and spring support surface to optimize the torque arm lengths and spring positioning. This allows the flapper plate to open completely under high pressure while the spring is positioned to provide variable torque that prevents overstressing during the opening and closing cycles.
Solution Approach 2:
The patent implements a variable torque spring mechanism where the spring force changes during the flapper plate rotation. The spring is positioned and configured to provide maximum torque when needed and reduced torque during other phases, dynamically adapting to the operational requirements and preventing constant overstress.
3Device complexity
If the hinge pin size is reduced to accommodate spring clearance, then the valve design is simplified, but the strength and sand resistance are compromised
Solution Approach 1:
The patent extracts the spring mounting function from the hinge pin area by providing a separate spring support surface on the flapper plate. This eliminates the need for hinge pin clearance, allowing the use of larger, stronger hinge pins that are more resistant to sand and wear, while the overall design remains relatively simple.
4Ease of operation
If clearance is provided near the pivot pin, then the torsion spring can be positioned, but the surrounding elements size is reduced
Solution Approach 1:
The patent extracts the spring positioning requirement from the pivot pin surrounding area by introducing a dedicated spring support surface on the flapper plate. This allows the torsion spring to be positioned without reducing the size of the hinge pin or surrounding elements, maintaining structural integrity and sand resistance.
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 enhances the reliability and efficiency of the flapper valve by providing consistent torque and reducing stress on the spring and plate, ensuring reliable operation in both open and closed positions, even under high-pressure conditions and in the presence of sand, without requiring significant material removal from the flapper plate.
Implementation Method 1
a spring that engages the flapper plate such that the flapper plate is biased toward the valve closed position
Implementation Method 2
The use of a beam spring with a unique dual-arm geometry and c-shape configuration that allows for variable torque
Data Source
AI summary
A flapper valve assembly including a tubular forming an interior passageway; a valve seat forming a portion of the interior passageway; a flapper plate that is pivotably mounted to the tubular at a pivot point such that the flapper plate is pivotable between a valve closed and a valve open position; and a spring engaging the flapper plate such that the flapper plate is biased towards the valve closed position; wherein, when the flapper plate is in the valve open position, the spring engages a top of the flapper plate at a first distance from the pivot point; wherein, when the flapper plate is in the valve closed position, the spring engages the top of the flapper plate at a second distance from the pivot point; and wherein the second distance is greater than the first distance.