Sub-nozzle Ejection Hole Geometry for Air Jet Loom Weft Conveying
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Solution Overview
Problem
Existing sub-nozzles for air jet looms face limitations in reducing air consumption while maintaining a desired weft conveying force, due to thin wall thickness leading to high air jet diffusion and increased pressure requirements.
Innovation Solution
The sub-nozzle design features a cylindrical portion connected to a compressed-air supply with a flat portion having an ejection hole formed across the distal end-side flat surface and side wall, where the ejection hole's center is closer to the reed, and includes a tapered portion to increase flow velocity, optimizing the axial-direction length and area ratio for improved weft conveying force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wall thickness of the ejection hole section is reduced to 0.5 mm or less, then the axial-direction length of the ejection hole becomes short and the ratio of axial-direction length to diameter becomes small, but this causes high diffusion of the air jet flow and reduces the weft conveying force with respect to supply pressure
Solution Approach 1:
The invention changes the geometric parameters of the ejection hole, specifically increasing the axial-direction length to diameter ratio to 0.05 or more. This is achieved by forming the ejection hole to extend through the wall thickness in the axial direction, thereby improving flow convergence and increasing the weft conveying force with respect to supply pressure while maintaining a thin wall structure
Solution Approach 2:
The invention transitions from a conventional ejection hole configuration to one where the hole extends axially through the wall, utilizing the third dimension (axial direction) more effectively. This dimensional change allows the ejection hole to achieve sufficient length for proper flow convergence without increasing the overall wall thickness
2Force
If the supply pressure is increased to obtain a desired weft conveying force, then the weft conveying force is improved, but the air consumption increases
Solution Approach 1:
By optimizing the ejection hole geometry (axial-direction length to diameter ratio of 0.05 or more), the invention improves the efficiency of compressed air utilization. This allows achieving the desired weft conveying force with lower supply pressure, thereby reducing air consumption while maintaining effective weft insertion
3Length of moving object
If the ejection hole is positioned closer to the reed (deviated from center axis), then the distance to the weft in the reed groove is reduced, but the wall thickness at the ejection hole section remains thin causing high diffusion
Solution Approach 1:
The invention addresses the thin wall issue at the deviated ejection hole position by ensuring the axial-direction length to diameter ratio is 0.05 or more. This geometric parameter change compensates for the potential loss of force due to high diffusion, maintaining effective weft conveying even with the ejection hole positioned closer to the reed
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
This design enhances weft conveying force with lower air pressure, reducing air consumption and improving flow convergence, allowing for effective weft insertion with reduced energy usage.
Implementation Method 1
the ejection hole is formed across the distal end-side flat surface portion and the side wall portion... a flow of air jetted from the ejection hole
Data Source
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AI summary
A sub-nozzle (2) for an air jet loom includes: a cylindrical portion (11) opening at one end thereof; and a flat portion (12) close to another end of the cylindrical portion and having an ejection hole (10). The flat portion has a hollow tube shape as a result of front and rear wall portions (18) and (17) facing each other being connected to each other by a side wall portion (19) and includes a distal end portion closed by the side wall portion. The front wall portion of the flat portion includes a distal end-side flat surface portion (21) close to the distal end portion at an outer surface (16) of the front wall portion and inclining to approach the rear wall portion toward the distal end portion. The ejection hole is formed across the distal end-side flat surface portion and the side wall portion.