Micro-Tunnelling Annular Seal for Drilling and Lubricating Fluid Separation
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Solution Overview
Problem
Conventional micro-tunneling machines face issues with increased lubricating fluid consumption, contamination of drilling fluid, and difficulty in controlling confining pressure due to unwanted mixing of lubricating and drilling fluids, especially on downward slopes.
Innovation Solution
Incorporation of an annular seal on the micro-tunneler's cylindrical body with a diameter equal to or greater than the cutting head, featuring flexible fins that separate drilling and lubricating fluids, maintaining confining pressure stability and reducing fluid mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lubricating fluid is injected outside the sinking pipes to reduce friction forces, then digging efficiency is improved, but lubricating fluid flows towards the cutting module and increases fluid consumption
Solution Approach 1:
The patent divides the annular space into two separate zones using a partitioning element: a first annular space for lubricating fluid injection outside the sinking pipes, and a second annular space for drilling fluid circulation around the cutting head. This segmentation prevents mixing and ensures each fluid performs its intended function without loss to the other system.
Solution Approach 2:
The partitioning element extracts the harmful mixing effect by physically separating the two fluid zones. The element includes a first portion extending radially from the sinking pipes and a second portion extending axially, creating distinct compartments that prevent lubricating fluid from flowing into the drilling fluid circulation path.
2Productivity
If lubricating fluid is injected under pressure to limit friction forces, then digging efficiency is improved, but drilling fluid becomes contaminated and requires treatment
Solution Approach 1:
The patent divides the annular space into two separate zones using a partitioning element: a first annular space for lubricating fluid injection outside the sinking pipes, and a second annular space for drilling fluid circulation around the cutting head. This segmentation prevents mixing and ensures each fluid performs its intended function without loss to the other system.
Solution Approach 2:
The partitioning element extracts the harmful mixing effect by physically separating the two fluid zones. The element includes a first portion extending radially from the sinking pipes and a second portion extending axially, creating distinct compartments that prevent lubricating fluid from flowing into the drilling fluid circulation path.
3Force
If lubricating fluid flows towards the cutting module, then friction forces are reduced, but confining pressure control becomes difficult
Solution Approach 1:
The patent divides the annular space into two separate zones using a partitioning element: a first annular space for lubricating fluid injection outside the sinking pipes, and a second annular space for drilling fluid circulation around the cutting head. This segmentation prevents mixing and ensures each fluid performs its intended function without loss to the other system.
Solution Approach 2:
The partitioning element acts as an intermediary barrier between the lubricating fluid and drilling fluid zones. It allows the lubricating fluid to perform its friction-reduction function outside the sinking pipes while preventing it from interfering with the confining pressure control in the drilling chamber.
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
Reduces lubricating fluid consumption, prevents fluid contamination, stabilizes confining pressure, and enhances digging efficiency by minimizing friction forces.
Implementation Method 1
the annular seal comes into contact with the ground during drilling to achieve a fluidic separation between the drilling fluid and the lubricating fluid
Implementation Method 2
a lubricating fluid is injected outside the jacking pipes, in the annular space between the extrados of the jacking pipes and the ground. In order to limit friction forces
Implementation Method 3
the drilling fluid, also called the slurry fluid, also serves to maintain a confining pressure providing frontal support for the excavation
Data Source
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AI summary
The invention relates to a microtunneling machine (12) comprising: a cutting module (100), a fluid circulation device (110) for injecting a drilling fluid (F) and aspirating drilling cuttings (D) in the front part of the cutting module, a device for injecting a lubricating fluid (L) outside the jacking pipe; The invention is characterized in that the cutting module (100) has an annular seal (150) located on the outer face (102a) of the cylindrical body (102), the diameter (D3) of the annular seal (150) being at least equal to the diameter (D2) of the cutter head (108), so that the annular seal (150) comes into contact with the ground during drilling to achieve fluid separation between the drilling fluid (F) and the lubricating fluid (L).