Spray Cap Air Shaping Passage for Uniform Coating

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Solution Overview

Problem

Existing spray coating devices often produce non-uniform spray patterns due to variations in air flow distribution, leading to suboptimal finish quality.

Innovation Solution

A spray cap with a flow control passage and expansion chamber that regulates and distributes air flow uniformly, improving the shape and quality of the spray by restricting air flow before expansion, thereby reducing pressure, velocity, and flow rate variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If air flow is supplied directly to spray outlets without flow control, then air flow rate is high and spray output is sufficient, but air flow distribution is non-uniform causing poor spray pattern quality

Engineering Contradiction:
Improvespray pattern uniformityVSAvoidair flow control structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The air cap is divided into multiple functional passages: a flow control passage with restricted cross-sectional area and an expansion chamber with larger volume. This segmentation allows the air flow to be regulated in stages, first restricting then expanding, which uniformizes the distribution while maintaining sufficient flow rate to the spray outlets.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The expansion chamber acts as an intermediary element between the flow control passage and the spray outlets. It receives the restricted air flow and allows it to expand and equalize before distribution, serving as a buffer that transforms non-uniform high-pressure flow into uniform distributable flow.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If air pressure is increased to improve spray output, then coating application rate increases, but air flow variations and turbulence increase causing non-uniform spray

Engineering Contradiction:
Improvecoating application rateVSAvoidspray uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The flow control passage and expansion chamber perform preliminary action on the air flow before it reaches the spray outlets. By restricting and then expanding the flow upstream, the system pre-uniformizes the air distribution, allowing high pressure to be maintained for productivity while the spray pattern remains uniform.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the physical parameters of air flow (pressure, velocity, cross-sectional area) through the flow control passage and expansion chamber. The restricted passage increases velocity and decreases pressure, while the expansion chamber reverses this, creating a more uniform flow distribution that maintains high overall flow rate for productivity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If flow restriction is added to uniformize air distribution, then spray pattern quality improves, but air flow rate decreases reducing productivity

Engineering Contradiction:
Improveair flow distribution uniformityVSAvoidspray output volume
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The expansion chamber provides an additional spatial dimension for flow equalization. Instead of simply restricting flow in one dimension, the system uses a volumetric expansion space where the restricted flow can distribute more uniformly in multiple directions before reaching the outlets, thereby maintaining higher overall flow rate while improving distribution uniformity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 results in a more uniform air flow distribution, enhancing the shape of the spray pattern and the quality of the coating applied, while also reducing noise and turbulence.

Implementation Method 1

a flow control passage which restricts the air shaping passage before expansion in the expansion chamber

Methodology Applied
Scientific EffectFlow restriction and expansion: Pressure Drop

Implementation Method 2

an expansion chamber downstream from the flow control passage

Methodology Applied
Scientific EffectPressure recovery through expansion: Pressure Drop

Data Source

PatentEP3445498B2Spray cap
Publication Date: 2024.06.19 CARLISLE FLUID TECHNOLOGIES LLC
  • EP3445498B2 patent drawingFigure 1
  • EP3445498B2 patent drawingFigure 2~3
  • EP3445498B2 patent drawingFigure 4~5

AI summary

A system, including a spray cap configured to couple to a spray tool (10, 12), wherein the spray cap includes a body and an air shaping passage (20) through the body. The air shaping passage (20) includes a flow control passage (14), an expansion chamber (18) downstream from the flow control passage, and one or more air shaping outlets downstream from the expansion chamber (18).