Electrostatic Coating Nozzle With Current Feedback Control
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Solution Overview
Problem
Deviation in the positions of the coating target and the conductor can hinder the uniformity of paint particle size, leading to a deterioration in coating quality during electrostatic atomization coating.
Innovation Solution
A coating device and method that measures the supplied current and controls the voltage applied to the nozzle based on this measurement to stabilize the electric field, using a configuration with insulated flow passages to minimize leakage current and ensure consistent paint droplet size and discharge speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If voltage is controlled according to distance between nozzles and conductor, then particle size uniformity is improved, but coating quality deteriorates when positional deviation occurs
Solution Approach 1:
The patent implements feedback control by measuring the supplied current and adjusting the voltage applied to the nozzle based on this measurement. The controller maintains a constant relationship between voltage and current, automatically compensating for positional deviations between the nozzle and conductor. This feedback mechanism ensures that particle size uniformity is maintained even when the distance varies, resolving the contradiction between achieving uniform particles and maintaining quality stability under positional deviation.
Solution Approach 2:
The patent replaces the mechanical distance-based control system with an electrical field-based control system. Instead of relying on precise mechanical positioning and distance measurements, the system uses electrical current measurement and voltage adjustment to maintain consistent atomization conditions. This substitution eliminates the sensitivity to positional deviations that plagues mechanical control systems.
2Stability of the object's composition
If distance-based voltage control is used, then electric field strength can be maintained, but positional deviations cause non-uniform electric field
Solution Approach 1:
The system uses current measurement as feedback to adjust the voltage dynamically. When positional deviation occurs causing electric field non-uniformity, the change in supplied current is detected and the voltage is adjusted to compensate, maintaining a constant voltage-current relationship. This feedback loop ensures that the electric field remains uniform despite variations in nozzle-conductor distance.
Solution Approach 2:
The patent changes the control parameter from distance-based voltage control to current-based voltage control. By measuring the supplied current and adjusting voltage accordingly, the system maintains a constant electrical parameter relationship (voltage-current proportionality) that is insensitive to positional changes. This parameter transformation resolves the contradiction between maintaining electric field strength and ensuring electric field uniformity under positional deviation.
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 effectively suppresses non-uniformity in the electric field due to positional deviations, maintaining consistent paint droplet size and discharge speed, thereby enhancing coating quality.
Implementation Method 1
Electrostatic atomization coating is a coating method in which paint is turned into fine droplets by the action of an electric field which is formed between an electrically charged nozzle and a conductor arranged opposing the nozzle
Implementation Method 2
the action of an electric field which is formed between an electrically charged nozzle and a conductor
Implementation Method 3
a measuring unit configured to measure a supplied current
Implementation Method 4
Since the strength of the electric field is a function of the distance between the positive and negative electrodes and the applied voltage
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A coating device 1A of the present invention is for atomizing a paint having an electrical resistivity of 20 MΩ·cm or less using an action of an electric field, and includes a nozzle 21 to which a voltage is applied, a flow passage 23 along which the paint flows, a measuring unit 42 that measures a supplied current, and a controller 5 that controls the voltage applied to the nozzle 21, based on a measurement value of the measuring unit.