Flapper Check Valve Closure Using Compression Spring and Cam

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Solution Overview

Problem

Current check valves in the oil and gas industry, relying on torsion springs, are prone to failure due to overstressing and limited cycle durability, leading to potential loss of function and uncontrolled fluid flow in the opposite direction.

Innovation Solution

A flapper check valve apparatus utilizing a tubular body with a pivotally moving flapper and an elastic actuator, featuring a compression spring and cam profile, which biases the flapper into a closed position when flow ceases, ensuring robust operation and maintaining function across multiple cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a torsion spring is used to activate the check valve, then the valve can prevent fluid flow in the opposite direction, but the spring is overstressed and fails after a small number of cycles

Engineering Contradiction:

Improvevalve function reliabilityVSAvoidspring cycle durability

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent extracts the problematic torsion spring from the system and replaces it with a compression spring mechanism. The compression spring is housed within a cavity in the valve body, separating the spring function from the flapper assembly. This extraction allows the use of a more durable spring type that isn't subjected to the same overstressing issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the spring type from torsion to compression, fundamentally altering the mechanical parameters of the actuation system. The compression spring operates within a defined cavity with specific clearance parameters, allowing it to function within safe stress limits while providing sufficient force to close the flapper against fluid pressure.

Inventive Principle:

Principle #35Parameter changes

2Force

If the torsion spring is designed to provide sufficient force, then the valve can close against fluid pressure, but the spring is limited to a small number of cycles before failure

Engineering Contradiction:

Improveflapper closing forceVSAvoidspring cycle life

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent introduces a cam surface as an intermediary between the compression spring and the flapper. The cam converts the linear motion of the compression spring into rotational motion of the flapper, providing mechanical advantage. This intermediary mechanism allows the spring to operate at lower forces while still achieving sufficient closing force on the flapper through the cam's leverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cam surface utilizes a curved profile with varying radius to provide mechanical advantage. The curved geometry allows the compression spring to exert force at one point while the cam translates this to rotational motion, effectively multiplying the force applied to the flapper hinge. This curved mechanism enables the spring to operate within safe stress limits.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Device complexity

If a torsion spring is used, then the valve structure can be compact, but the spring breaks resulting in loss of function

Engineering Contradiction:

Improvevalve structure compactnessVSAvoidspring failure and fluid flow loss

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent designs the compression spring system with built-in clearance and cushioning features. The spring operates within a cavity with defined clearance between the spring ends and the cavity walls, preventing the spring from bottoming out or experiencing extreme stresses. This beforehand cushioning design prevents catastrophic failure even after extended operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent employs a simple compression spring and cam mechanism that can be easily manufactured and replaced if needed. The design uses conventional, readily available components rather than complex torsion spring assemblies, making the system more reliable and easier to maintain throughout its service life.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 flapper check valve apparatus provides a more robust solution with lower operating stresses and higher reliability, ensuring the valve remains functional across multiple service intervals and maintains fluid control in any orientation, even against gravity.

Implementation Method 1

an elastic actuator adjacent to the flapper; wherein the flapper is activated by the compressed elastic actuator, which has an ability to bias the flapper into a closed position when a flow is stopped

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11261980B2Apparatus and method for activation of flapper check valve

Publication Date: 2022.03.01 COIL USA INC

AI summary

A flapper check valve employed to prevent flow up the work string while allowing flow down the work string and into the well is disclosed. The check valve is activated by a compression spring, which then acts on a ball which will further act on a cam profile attached to the back of a flapper. The apparatus causes the flapper to default to the closed position when the flow is stopped, regardless of the position of the valve, even when gravity is acting against the flapper. The compression spring also allows for an apparatus which possesses lower operating stresses on the spring.