Pressure Swirl Nozzle for Curable Composition Spray Stability
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Solution Overview
Problem
Existing pressure swirl atomizing nozzles struggle to maintain a consistent spray pattern and droplet size when varying the flow rate of high-viscosity polyurethane reaction mixtures, leading to overspray and reduced mechanical properties due to larger droplets and instability.
Innovation Solution
The nozzle design positions the injector piece closer to the exit orifice, with a reduced surface area of the swirl chamber and smaller cross-sectional areas of the swirl ports, to minimize the effect of flow rate changes on droplet size, ensuring a stable and uniform spray pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flow rate of curable composition is reduced to spray from a short distance, then overspray is reduced and uniformity is improved, but droplet size increases significantly leading to larger air bubbles and worse mechanical properties
Solution Approach 1:
The patent changes the geometric parameters of the nozzle, specifically reducing the surface area of the swirl chamber and the cross-sectional areas of the swirl ports. This parameter change allows the nozzle to maintain stable droplet size (MVD) even when flow rate is reduced, thereby preventing the formation of large air bubbles while still enabling short-distance spraying for uniform application
Solution Approach 2:
The patent enables dynamic adjustment of flow rate while maintaining stable spray characteristics. By optimizing the swirl chamber geometry, the nozzle can adapt to varying flow rates without significant droplet size variation, allowing operators to dynamically adjust flow rate based on spray distance and surface area while maintaining mechanical properties
2Quantity of substance
If pressure is reduced to decrease flow rate, then material usage is optimized, but droplet size increases by about 65% according to conventional nozzles
Solution Approach 1:
The patent changes the geometric parameters of the nozzle, specifically reducing the surface area of the swirl chamber and the cross-sectional areas of the swirl ports. This parameter change allows the nozzle to maintain stable droplet size (MVD) even when flow rate is reduced, thereby preventing the formation of large air bubbles while still enabling short-distance spraying for uniform application
Solution Approach 2:
The patent enables dynamic adjustment of flow rate while maintaining stable spray characteristics. By optimizing the swirl chamber geometry, the nozzle can adapt to varying flow rates without significant droplet size variation, allowing operators to dynamically adjust flow rate based on spray distance and surface area while maintaining mechanical properties
3Adaptability or versatility
If the nozzle is made small to access narrow cavities, then adaptability to complex mould surfaces is improved, but spray distance is reduced leading to potential overspray
Solution Approach 1:
The optimized nozzle geometry enables stable spray pattern at reduced spray distances. By minimizing droplet size variation, the nozzle maintains control over spray dispersion even when positioned close to the mould surface, reducing overspray while enabling access to narrow cavities and complex geometries
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 allows for variable flow rates with reduced droplet size variation, enhancing the uniformity and mechanical properties of the sprayed polyurethane layer, while preventing overspray and maintaining efficiency.
Implementation Method 1
The injector piece comprises two or more swirl ports through which the curable composition is injected into the swirl chamber. Due to the obtained swirling motion, the curable composition is sprayed out of the exit orifice in the form of a hollow spray cone.
Implementation Method 2
the curable composition is injected into the swirl chamber under a pressure gradient
Implementation Method 3
the curable composition is sprayed out of the exit orifice in the form of a hollow spray cone
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The pressure swirl atomizing nozzle for spraying a curable composition comprises an orifice piece (16), which defines a funnel-shaped cavity and an exit orifice (17), and an injector piece (18) which closing off the funnel- shaped cavity so that the funnel-shaped cavity forms a swirl chamber (19) between a front side of the injector piece (18) and the exit orifice (17). The injector piece (18) comprises at least two swirl ports (20) which end in the swirl chamber (19) for injecting the curable composition therein and for thereby imparting swirl to the curable composition. Compared to the sum of the smallest cross-sectional areas of the swirl ports (20), the side wall (24) of the swirl chamber (19) has a relatively small surface area which is however still large enough to distribute the curable composition so as to achieve a uniform spray pattern. By the reduced size of the swirl chamber (19), the curable composition can be atomized more efficiently. In this way, changes of the relatively low flow rate of the curable composition through the nozzle have less effect on the droplet size and on the stability of the spray pattern.