Spray Gun Air Cap Angle and Pressure Ratio for Atomization
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Solution Overview
Problem
Existing spray guns used in vehicle refinish coating applications have low atomization efficiency, resulting in large paint droplets and poor transfer efficiency, especially when operating at low air cap pressures, which limits their effectiveness in achieving high-quality coatings.
Innovation Solution
A spray gun design featuring a fluid spray nozzle and air cap configuration that directs atomization air at an angle of 10-75 degrees relative to the liquid coating composition jet, with an atomizing air pressure to fan air pressure ratio of 8:1 to 1.5, allowing for high atomization efficiency and smaller droplet sizes, achieved through specific air distribution channel diameters and flow regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low air cap pressure is used in conventional spray guns, then energy consumption is reduced and operation is easier, but atomization efficiency deteriorates resulting in large paint droplets
Solution Approach 1:
The patent changes the pressure ratio parameter between atomizing air and fan air from conventional values to a specific range (atomizing air pressure 1-5 bar, fan air pressure adjusted to achieve optimal ratio), which enables high-quality atomization at lower overall pressures, resolving the contradiction between ease of operation and atomization quality
Solution Approach 2:
The patent introduces adjustable air flow regulation means that allow dynamic adjustment of the atomizing air and fan air flow rates and pressures, enabling the system to adapt to different operating conditions and maintain optimal atomization across varying requirements, thus resolving the contradiction between operational simplicity and atomization precision
2Manufacturing precision
If high atomization pressure is used to achieve small droplet sizes, then atomization efficiency is improved, but transfer efficiency deteriorates due to excessive spray dispersion
Solution Approach 1:
The patent optimizes the pressure ratio parameter between atomizing air and fan air, maintaining atomizing air pressure at 1-5 bar while adjusting fan air pressure to achieve an optimal balance that produces fine droplets (improving atomization efficiency) while controlling spray dispersion to maintain transfer efficiency above 65%
Solution Approach 2:
The patent applies different air pressures and flow rates to different functions: higher atomizing air pressure for droplet formation and lower controlled fan air pressure for spray pattern management, creating localized quality differences that simultaneously achieve fine atomization and controlled dispersion for high transfer efficiency
3Device complexity
If conventional air cap designs are used with limited pressure ratios, then device complexity is reduced, but atomization efficiency deteriorates
Solution Approach 1:
The patent incorporates adjustable air flow regulation means including valves and flow controllers that enable dynamic adjustment of atomizing air and fan air parameters, transforming a static simple design into a dynamic system that achieves high atomization efficiency (droplet sizes 10-50 micrometers) while maintaining reasonable complexity through standardized components
Solution Approach 2:
The patent changes the pressure ratio parameter to a specific range (atomizing air pressure 1-5 bar with adjusted fan air pressure) that enables high atomization efficiency, using appropriately sized air distribution channels and regulation means to achieve this parameter optimization without excessive device complexity
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 design enhances atomization efficiency, producing a stable and homogeneous spray cone with transfer efficiencies between 65-92%, suitable for a wide range of liquid paints and substrates, including vehicle bodies and other materials.
Implementation Method 1
at least one air distribution channel for atomizing air... configured to direct an atomization air flow... into the pre-atomized coating composition jet... showing high level of liquid paint atomization, resulting is smaller liquid paint droplets
Implementation Method 2
by selecting appropriate air distribution channel diameters and/or by including appropriate means for regulating the air flow volumes in the separate air distribution channels at given air distribution channel diameters
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3B
AI summary
A spray gun and a method for use thereof comprises a spray gun body; an air cap; a fluid spray nozzle having a fluid tip; at least one air distribution channel for atomizing air; and at least one air distribution channel for fan air, wherein the fluid spray. The fluid spray nozzle and the air cap are configured to direct an atomization air flow at an angle of substantially 10 to 70 degrees relative to the liquid coating composition jet, into the pre-atomized coating composition jet and produce an atomization air pressure to fan air pressure ratio of substantially 8.0 to 1.5.