Cageless Lock Assembly Dogs Radial Transition
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Solution Overview
Problem
Existing lock assemblies in the downhole drilling and completions industry face structural weaknesses due to the need for windows and struts, which can lead to failure under high pressure and loading conditions, as they require balancing the width of dogs and struts to maintain load-bearing area and structural integrity.
Innovation Solution
A 'cageless' or 'windowless' lock assembly design that transitions dogs between retracted and extended configurations using extender bodies with ramped sections, eliminating the need for struts and maximizing load-bearing surface areas without compromising structural strength, by allowing dogs to form a circumferentially continuous shape in the retracted position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If windows and struts are used to accommodate dogs in the lock assembly, then the structural framework is established, but the load-bearing capacity is reduced due to the need to balance strut width with dog width
Solution Approach 1:
The patent removes the strut component entirely from the lock assembly design. By extracting the strut, the invention eliminates the need to balance strut width with dog width, thereby maximizing the load-bearing surface area of the dogs without compromising structural integrity through the window and strut framework.
Solution Approach 2:
The patent divides the lock assembly into discrete functional components: dogs for load bearing, extender bodies for radial transition, and mandrels for support. This segmentation allows each component to be optimized independently, with the dogs having maximum width without being constrained by strut dimensions.
2Strength
If the width of dogs is increased to maximize load bearing area, then the load-bearing capacity improves, but the structural integrity is compromised due to insufficient strut support
Solution Approach 1:
By removing the strut component, the invention eliminates the source of structural weakness. The dogs can achieve maximum width and load-bearing capacity without being constrained by the need to maintain adequate strut support, thereby resolving the contradiction between load-bearing capacity and structural integrity.
Solution Approach 2:
The invention transitions from a two-dimensional window-and-strut framework to a three-dimensional configuration where dogs extend radially from the mandrel. This dimensional change allows the dogs to bear loads directly against the mandrel surface, eliminating the need for strut-mediated support and maximizing both load-bearing capacity and structural integrity.
3Reliability
If struts are made wider to improve structural integrity, then the reliability improves, but the load-bearing area available for dogs is reduced
Solution Approach 1:
The invention extracts and removes the strut component entirely, thereby eliminating the space that would otherwise be occupied by struts. This allows the dogs to have maximum width and access to the full load-bearing surface area of the mandrel, while structural integrity is maintained through the direct engagement between dogs and mandrel.
4Ease of operation
If a windowed design is used to accommodate dogs, then the dogs can be positioned radially, but the struts create failure points under high pressure conditions
Solution Approach 1:
The invention removes the strut component that creates failure points under high pressure. The radial positioning capability is maintained through the extender body mechanism, but the windowed design is eliminated, removing the weak points that would compromise reliability under pressure.
Solution Approach 2:
The lock assembly is segmented into functionally independent components: extender bodies for radial transition, dogs for load bearing, and mandrels for support. This segmentation allows the system to achieve radial positioning capability without creating the window-and-strut configuration that introduces failure points under pressure.
Data Source
AI summary
A lock assembly including a plurality of dogs, each dog having a load bearing surface and a first interconnection feature. An extender body is operatively arranged for radially transitioning the plurality of dogs between a retracted configuration and an extended configuration. The load bearing surface of each dog is operatively arranged in the extended configuration for engaging against a shoulder of a radially adjacent structure for supporting the lock assembly. A mandrel is included having a second interconnection feature operatively arranged to dimensionally overlap the first interconnection feature of the dogs when transitioned to the extended configuration for enabling the mandrel to be supported by the dogs. A method of locking radially adjacent components is also included.