Intermittent Coating Nozzle Spacing Control
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Solution Overview
Problem
Existing intermittent coating methods for fuel cell electrolyte membranes struggle to achieve uniform coating shapes at the start and end of the coating process, leading to wasteful consumption of expensive platinum catalysts and potential decreases in fuel cell performance due to protrusions or shrinkages of the catalyst ink.
Innovation Solution
An intermittent coating method and apparatus that utilize a slit nozzle with controlled spacing adjustments to ensure uniform coating, where the nozzle moves from a larger contact gap to a smaller coating gap and then to a termination gap, allowing for precise application and drying of catalyst ink on continuously moving electrolyte membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed spacing between the slit nozzle and base material is used during intermittent coating, then the coating process is simple to control, but the coating shape becomes non-uniform at the start and end of coating
Solution Approach 1:
The patent applies the dynamics principle by making the spacing between the slit nozzle and base material variable rather than fixed. The spacing is dynamically adjusted to be larger at the start and end of coating, and smaller during the middle coating phase, enabling uniform coating shapes throughout the coating region while managing the complexity through controlled temporal variation.
2Manufacturing precision
If the liquid pool size at the nozzle tip is not controlled, then the coating process is simpler, but the coating uniformity and catalyst usage efficiency deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the size of the liquid pool formed at the tip of the slit nozzle. The liquid pool size is adjusted as a controllable parameter to ensure uniform coating application, and the relationship between liquid pool size and coating uniformity is established to optimize catalyst ink distribution and prevent waste.
3Loss of substance
If coating is performed without precise spacing control, then the device operation is simpler, but catalyst ink protrusion and shrinkage occur leading to material waste
Solution Approach 1:
The patent applies preliminary action by pre-controlling the liquid pool formation at the nozzle tip before coating begins, and by pre-establishing the spacing variation pattern. This preliminary preparation ensures that when coating occurs, the catalyst ink is applied uniformly without protrusion or shrinkage, reducing material waste while maintaining operational simplicity through automated control.
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 approach ensures uniform coating shapes at both the start and completion of the coating process, reducing catalyst ink wastage and maintaining fuel cell performance by preventing protrusions and shrinkages, thereby optimizing the use of expensive platinum catalysts.
Implementation Method 1
a liquid pool of a coating liquid is formed at a tip of the slit nozzle
Data Source
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AI summary
With an electrolyte membrane travelling continuously at constant speed in a roll-to-roll process, a catalyst ink is intermittently applied to the front surface of the electrolyte membrane from a coating nozzle. A liquid pool of the catalyst ink is formed at the tip of the coating nozzle during an intermission of coating. At the start of coating, the coating nozzle moves such that the spacing between the coating nozzle tip and the electrolyte membrane front surface is equal to a contact gap different from a coating gap to bring the liquid pool into contact with a coating start end of a coating area, suitably coating the catalyst ink to the coating area. The contact gap becomes larger with a larger film thickness of a coating formed on the front surface of the electrolyte membrane, and is larger than the coating gap for the film thickness larger than a predetermined value.