One-Piece Ball Valve Cage Assembly for Zero-Restriction Flow

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Solution Overview

Problem

Traditional ball check valves in downhole reciprocating pumps suffer from fluid flow restrictions, premature failures due to ball rattling, and assembly issues like interference fits and threaded connections, leading to inefficiencies and costly repairs.

Innovation Solution

A one-piece cage assembly with a unitary insert made from hard, wear-resistant materials, featuring a fluid seal screw thread connection and designed to minimize fluid restriction and prevent ball rattling, eliminating the need for multiple piece assemblies and reducing pre-stress on components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If interference fit or shrink fit is used to hold the insert in the cage, then the insert is securely held, but fluid flow is restricted and radial stress is caused on the insert

Engineering Contradiction:

Improveinsert retentionVSAvoidfluid flow restriction

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The cage is divided into two separate pieces: the main cage body and the cage end. The insert is retained by threading the cage end onto the main cage body, creating a segmented assembly that avoids interference fit and allows unobstructed fluid flow through the insert-cage interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The threaded connection acts as an intermediary mechanism between the insert and the cage assembly. Instead of direct interference fit, the threaded cage end provides indirect retention, eliminating radial stress on the insert while maintaining secure positioning.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If friction welding is used to join cage pieces, then the cage is securely assembled, but the insert undergoes high axial compression stress causing cracks

Engineering Contradiction:

Improvecage assembly integrityVSAvoidinsert crack resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cage is segmented into two pieces joined by threading rather than friction welding. This eliminates the high axial compression stress that occurs during friction welding, preventing insert cracks while maintaining assembly integrity through the threaded connection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The friction welding mechanical process is replaced with a threading mechanism. Instead of applying high axial compression through friction welding, the threaded connection provides secure assembly without subjecting the insert to damaging compressive stresses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If multiple pieces of cage are assembled with threaded connections and rubber gasket, then assembly is flexible, but the gasket leaks and threaded connections fail under pumping stresses

Engineering Contradiction:

Improveassembly flexibilityVSAvoidseal integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The rubber gasket is completely removed from the design. The seal is achieved through the precision threaded connection between the cage end and main cage body, eliminating the unreliable gasket component that leaks under pumping stresses.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The design eliminates disposable seal components like rubber gaskets that fail over time. The permanent threaded metal-to-metal connection provides lasting seal integrity without requiring replacement of consumable sealing elements.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Ease of operation

If diametrical clearance of 0.762 mm or greater is maintained between ball and insert bore, then ball movement is free, but the ball rattles rapidly causing premature failure

Engineering Contradiction:

Improveball movement freedomVSAvoidinsert and cage durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The diametrical clearance parameter is optimized to a specific range that balances ball movement freedom with rattling prevention. This controlled parameter change allows the ball to move freely for proper valve operation while minimizing rapid rattling that causes premature failure.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11125349B1Zero restriction ball valve insert, one-piece cage and assembly

Publication Date: 2021.09.21 ELLIS MFG CO INC

AI summary

An improved one-piece cage and an improved insert and their assembly create a zero-restriction fluid flow ball check valve. The improved insert for ball and seat valve comprises external screw threads on the base of the insert and have circumferentially spaced ribs extending upwards and converging towards the longitudinal axis of the insert, forming a hemi-spherical ball stop and arched side openings. The inside diameter of the insert bore is substantially equal to the ball valve diameter preventing the ball from rattling when positioned in the improved insert's passageway during the fluid flow. The outside diameter of the ribs is less than the inside diameter of the improved one-piece cage cavity producing a zero-restriction fluid flow ball check valve in comparison to the volumetric fluid flow through the annular seat. The improved cage that receives the improved insert is a one piece in construction and has internal threads that correspond to the external threads on the improved insert. The insert is assembled inside the cage using a screw thread connection and simultaneously forming a fluid seal between the insert and the cage.