Prestressing Cable Sheath Vent with Air-Permeable Filter
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Solution Overview
Problem
In prestressing cables, especially those with external removable systems, air evacuation at high points is challenging due to the small space between formwork tubes and HDPE tubes, leading to air pockets and incomplete filling of the sheath, making it difficult to ensure proper filling without operator intervention.
Innovation Solution
A vent system with a filter element that is permeable to air but impermeable to filling products is integrated into the sheath, allowing air evacuation without blocking the filling material, ensuring complete air evacuation and filling without operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional vent is installed in the tight space between formwork tube and HDPE tube, then air evacuation should be improved, but the small curved space makes installation impossible and creates voids
Solution Approach 1:
The patent applies a porous filter element that allows air to pass through while blocking the filling material. This porous medium is integrated directly into the sheath at the high point, enabling air evacuation without requiring a complex mechanical vent structure. The porous material's unique property of being permeable to air but impermeable to filling product solves the contradiction by providing a simple, installable solution that effectively removes air pockets.
Solution Approach 2:
The filter element acts as an intermediary substance between the air and the filling material. It mediates the interaction by allowing air to escape while preventing the filling material from entering the vent space. This intermediary approach enables air evacuation in the tight curved space without requiring a complex mechanical vent structure, thus resolving the contradiction between effective air removal and installation simplicity.
2Reliability
If filling material is re-injected through holes on either side of the high point to compensate for lack of vent, then complete filling may be achieved, but the process becomes complex and delicate requiring operator intervention
Solution Approach 1:
The filter element enables the system to self-regulate during the filling process. As the filling material advances, it automatically contacts the filter element at the high point, which then blocks the vent and prevents further air escape. This self-blocking mechanism ensures complete filling without requiring operator intervention or complex manual operations, thus resolving the contradiction between reliable filling completeness and operational simplicity.
3Object-generated harmful factors
If a vent is installed to evacuate air, then air pockets are reduced, but the vent may block the filling material passage
Solution Approach 1:
The patent employs a porous filter element with specific pore size characteristics that differentiate between air and filling material. The porous structure allows air molecules to pass through while the larger filling material particles are blocked. This selective permeability resolves the contradiction by enabling air evacuation without compromising filling material flow, as the porous material physically distinguishes between the two substances based on their size and properties.
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 enables efficient air evacuation and complete filling of the sheath, reducing the need for operator intervention and eliminating air pockets, even in tight spaces, thus improving the efficiency of the prestressing cable filling process.
Implementation Method 1
the vent comprises a filter element permeable to air and impermeable to the filling product
Implementation Method 2
the filter element has a porosity of between 0.5 μm and 200 μm
Data Source
Figure 1~2
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Figure 5~6
AI summary
Sheath for prestressing cable comprising a tubular sheath body (11) and at least one vent (20) between the inside of the sheath and the outside of the sheath, characterized in that the vent (20) has a filter element (21) permeable to air and impermeable to a filling product from the inside of the sheath.