Well Tool Ratchet System Backlash Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior art ratchet systems in well tools allow undesired relative axial movement, leading to backlash that can cause the tool to loosen its engagement with the well pipe, necessitating the use of springs to mitigate this issue, which increases complexity and length, and can result in plastic deformation under high pressures.
Innovation Solution
A ratchet system with two locking rings and ring-shaped or spiral-shaped tracks that allow relative axial movement between the mandrel and locking rings in one direction while preventing it in the opposite direction, using annular end surfaces for force transfer and ring elements to minimize backlash, allowing for radial expansion without increasing the locking ring's diameter or thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ratchet system with grooved surfaces is used to allow radial expansion, then the locking ring can expand radially, but relative axial movement and backlash occur between components
Solution Approach 1:
The ratchet system is divided into multiple independent locking rings (first locking ring with grooved inner surface, second locking ring with grooved outer surface) that engage with each other and with the mandrel/housing separately. This segmentation allows each ring to handle radial expansion independently while the combined system prevents axial movement, resolving the contradiction between expansion capability and axial stability.
2Reliability
If springs are added to prevent backlash, then axial engagement stability improves, but device complexity and length increase
Solution Approach 1:
The spring mechanism is completely removed from the system. Instead of using elastic elements to prevent backlash, the invention uses a purely mechanical ratchet-to-ratchet engagement system where the grooved surfaces of the locking rings interlock to prevent relative axial movement without requiring any elastic compensation components.
3Reliability
If the locking ring diameter or thickness is increased to improve engagement, then axial stability improves, but the tool cannot be run into the well
Solution Approach 1:
The locking rings are designed with nested dimensions where the first locking ring fits within the outer housing and the second locking ring engages with the first locking ring. This nesting allows the system to achieve strong engagement through multiple contact surfaces rather than increasing the overall diameter or thickness of individual components, maintaining tool runnability while improving engagement strength.
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 reduces the relative axial displacement between the housing and locking device, minimizing backlash and the need for springs, while maintaining effective engagement with the well pipe under high pressures and temperatures, thus enhancing the tool's stability and operational efficiency.
Implementation Method 1
a ratchet system comprising: an grooved outer surface area (32) of the mandrel device (10); a locking ring (40) with a grooved inner surface area (42) engaged with the grooved outer surface area (32) of the mandrel device (10)
Implementation Method 2
an axial slit (41) in the locking ring (40) to allow radial expansion of the locking ring (40) by movement of the grooved inner surface area (42) relative to the grooved outer surface area (32)
Implementation Method 3
where the first and second locking rings (40, 50) are minimizing relative axial displacement between each other through their annular end surfaces (46, 48, 56, 58)
Data Source
AI summary
A well tool device includes a mandrel device having an axial center axis, a housing device provided radially outside of the mandrel device, and a ratchet system. The ratchet system includes a grooved outer surface area of the mandrel device, a first locking ring including a grooved inner surface area engaged with the grooved outer surface area of the mandrel device, a grooved outer surface area, and an axial slit allowing radial expansion of the first locking ring. The first locking ring is engaged with the outer housing. The ratchet system is configured to allowing relative axial movement between the mandrel device and the first locking ring in a first axial direction and to prevent relative axial movement between the mandrel device and the locking ring in a second direction opposite of the first direction. The ratchet system further includes a second locking ring provided radially outside the first locking ring, the second locking ring including a grooved inner surface area engaged with the grooved outer surface area of the first locking ring, and an axial slit allowing radial expansion of the second locking ring. The second locking ring is engaged with the outer housing.