Nozzle Assembly Auxiliary Apertures Air Flow Alignment
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Solution Overview
Problem
Existing spray gun nozzle assemblies face challenges with boundary layer separation in auxiliary apertures, leading to skewed air flow and distribution issues, and difficulties in mass manufacturing due to asymmetric molding pins, which increase costs and complexity.
Innovation Solution
The design incorporates countersunk auxiliary apertures with axially symmetric ledges on the inner surface of the air cap, improving air flow alignment and reducing manufacturing complexities by allowing for symmetrical pin orientation during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If auxiliary apertures are located at flanking positions alongside the atomizing and liquid apertures, then air flow can be directed to shape the spray field, but boundary layer separation occurs causing skewed air flow and adverse distribution effects
Solution Approach 1:
The patent applies asymmetry by positioning the auxiliary aperture offset from the central axis rather than symmetrically. This asymmetric positioning allows the aperture to be located in a region where boundary layer separation is minimized, thereby achieving more uniform air flow distribution while maintaining spray field shaping capability. The offset position strategically avoids the skewed flow patterns that would occur with symmetric flanking positions.
2Ease of manufacture
If auxiliary apertures are drilled into the faceplate with uniform diameter, then manufacturing is simplified, but air flow profile uniformity is compromised due to boundary layer separation
Solution Approach 1:
The patent applies local quality by varying the diameter of the auxiliary aperture along its length rather than maintaining a uniform diameter. The aperture has a larger diameter at the inlet and a smaller diameter at the outlet, creating a tapered configuration. This local variation in geometry compensates for boundary layer separation effects and produces a more uniform air flow profile while remaining manufacturable through standard drilling and tapering processes.
3Manufacturing precision
If wall thickness is increased to lengthen the auxiliary aperture, then air flow profile uniformity improves, but material costs and weight increase
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the auxiliary aperture, specifically the diameter along its length. By creating a tapered aperture with varying diameter rather than increasing wall thickness, the design achieves improved air flow profile uniformity through optimized flow characteristics. This approach maintains the original wall thickness and overall component dimensions, thereby avoiding increased weight and material costs while still achieving the desired flow uniformity.
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 configuration enhances the uniformity of the air flow profile, reduces material costs, and simplifies the manufacturing process while maintaining the efficiency of the spray pattern distribution.
Implementation Method 1
air flow behind the auxiliary apertures is subject to a phenomenon called boundary layer separation. As a result, air flow within the auxiliary apertures can separate from the inside edge surfaces, causing air flow to become skewed within the auxiliary apertures
Implementation Method 2
The fast-moving air flows out of the atomizing apertures through a region of reduced pressure. The air breaks up the liquid from the liquid aperture to form a spray field of fine droplets in a process called atomization
Implementation Method 3
These air jets work by re-distributing the spray field proximal to the front face surface of the spray nozzle
Data Source
AI summary
Provided are nozzle assemblies for a spraying apparatus having an outer wall (146) having opposed inner and outer surfaces, a central aperture (136) extending through the outer wall, and a pair of auxiliary apertures (158) disposed on the outer wall (146). Each auxiliary aperture is aligned along a respective auxiliary axis (162) and areas of the inner surface (164) of the outer wall (146) adjacent to the auxiliary apertures (158) are countersunk to define ledges (166) that are axially symmetric about the auxiliary axes (162). These assemblies obviate problems associated with rotatable molding pins and also provide the unexpected advantage of providing axial alignment of the air flow profile as air is emitted from the auxiliary apertures.