Rotary Electrostatic Sprayer Air Ejection Skirt

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Solution Overview

Problem

Conventional rotating electrostatic coating projectors used for both external and internal surfaces, such as motor vehicle bodies, face frequent contamination and require frequent cleaning, leading to operational interruptions due to the accumulation of paint overspray and electrostatic charge issues, which reduces their effective usage duration.

Innovation Solution

A rotating electrostatic projector design featuring a spray bowl, turbine-driven rotation, electrodes on a ring, and an annular air ejection skirt with a pressurized air flow circuit that directs air towards the front of the projector, preventing paint deposition and reducing contamination by continuously cleaning the external surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrodes and resistors are mounted inside a ring fixed to the outside of the body of a rotating electrostatic projector, then the projector can effectively coat surfaces, but the portion of the projector body located in front of this ring becomes soiled and requires regular cleaning, resulting in long interruptions in operation

Engineering Contradiction:
Improvecoating effectivenessVSAvoidoperational interruption time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention extracts the harmful soiling problem by introducing a dedicated air flow system that actively removes coating deposits from the projector body surface. The air vent and air supply duct create a continuous cleaning effect, separating the coating function from the contamination accumulation, thereby reducing operational interruptions without compromising coating effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies preliminary action by establishing a continuous air flow that prevents coating deposits from accumulating on the projector body in the first place. The air vent positioned near the electrodes and the air supply duct create a protective air curtain that repels overspray before it can soil the body, eliminating the need for frequent cleaning interruptions

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If spray guns are used to coat the interior surfaces of an object, then coating can be applied to hard-to-reach areas, but the spray guns are highly susceptible to overspray and get dirty quickly, particularly around their electrodes

Engineering Contradiction:
Improvecoating coverage capabilityVSAvoidoverspray contamination
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The invention introduces air as an intermediary substance that mediates between the coating application process and the projector body. The air flow from the vent and duct acts as a protective barrier that prevents overspray from directly contacting and contaminating the electrodes and body, allowing the spray gun to maintain coating versatility while reducing contamination

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If an annular air vent is provided near the electrodes of an electrostatic projector, then air flow can be directed towards the front, but the air supply duct does not prevent electrostatic charges from creeping towards an internal grounded part of the projector, which impairs the efficiency of the charge obtained with the electrodes

Engineering Contradiction:
Improvecleaning capabilityVSAvoidelectrostatic charge efficiency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention applies local quality by positioning the air vent specifically near the electrodes where contamination risk is highest, and directing air flow precisely where needed to protect the charging mechanism. The air supply duct is configured to create a localized protective zone around the electrodes without interfering with the electrostatic charge distribution, thereby maintaining both cleaning effectiveness and charge efficiency

Inventive Principle:
Principle #3Local quality

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 projector operates with reduced need for frequent cleaning, maintaining efficiency and extending operational intervals by continuously cleaning the external surfaces with a directed air flow, thus minimizing paint accumulation and electrostatic charge interference.

Implementation Method 1

An annular slot supplied by a pressurized airflow circuit is defined radially between the ring and the skirt, with its outlet directed towards the front of the projector

Methodology Applied
Scientific EffectPressurized air flow: Pressure Gradient

Implementation Method 2

a turbine mounted in this body and configured to drive the bowl in rotation around an axis defined by the body

Methodology Applied
Scientific EffectTurbine rotation: Turbine

Implementation Method 3

It is known to charge a coating product leaving the spray nozzle of a spray bowl by the corona effect, using electrodes arranged on the body of a sprayer and held at high voltage

Methodology Applied
Scientific EffectCorona effect: Corona Discharge

Implementation Method 4

The chamber is delimited, particularly at the front, by a compression seal between the skirt and the body

Methodology Applied
Scientific EffectCompression seal: Compression

Data Source

PatentEP3831499B1Rotary electrostatic sprayer for coating product, spraying installation comprising such a sprayer and method for coating by means of such a sprayer
Publication Date: 2023.11.15 EXEL INDUSTRIES
  • EP3831499B1 patent drawingFigure 1
  • EP3831499B1 patent drawingFigure 2
  • EP3831499B1 patent drawingFigure 3

AI summary

This rotating electrostatic coating sprayer includes a spray bowl, a body (102), and a drive turbine mounted in the body and configured to rotate the spray bowl about an axis of rotation (A100) defined by the body. The sprayer also includes electrodes (140) for charging the coating product sprayed by the spray bowl, these electrodes being mounted on a ring (160) attached to the body, and an air ejection skirt (124) around the bowl. An annular slot (232), supplied by a pressurized air flow circuit (F3), is defined radially between the ring (160) and the skirt (124) with its outlet (234) directed toward the front of the sprayer.