Filter Substrate Coating Apparatus Using Gravity and Vacuum
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Solution Overview
Problem
Existing methods for coating filter substrates with washcoats face challenges in achieving uniform coating depth and control over washcoat location, particularly for substrates with large diameters and low viscosity washcoats, which are difficult to process and result in batch variability and changes in properties over time.
Innovation Solution
A method and apparatus that introduce a pre-determined amount of liquid into the upper end of a filter substrate, allowing gravity to assist in coating the channels, and using a vacuum at the lower end to draw the liquid into the substrate, enabling precise control over washcoat location and coating depth, even with low viscosity washcoats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pre-determined amount of liquid is introduced into the upper end of the filter substrate with gravity assistance, then the coating uniformity and control over washcoat location is improved, but the device complexity increases due to the need for vacuum application system at the lower end
Solution Approach 1:
The patent inverts the conventional coating approach by introducing liquid at the upper end of the substrate rather than the lower end. The liquid is introduced into the upper open ends of the channels, allowing gravity to assist flow downward through the channels, while a vacuum applied at the lower end draws the liquid through. This inversion enables precise control over coating depth and location by controlling the vacuum application.
Solution Approach 2:
The patent employs pneumatic principles by applying a vacuum at the lower end of the substrate to draw the liquid washcoat through the channels. The vacuum system creates a pressure differential that controls the liquid flow and coating process, enabling precise control over coating uniformity and depth without requiring complex mechanical delivery systems.
2Ease of operation
If low viscosity washcoats are used, then the ease of operation and handling is improved, but the manufacturing precision deteriorates due to difficulty in achieving uniform coating depth
Solution Approach 1:
By inverting the coating process to introduce liquid at the upper end and draw it through with vacuum at the lower end, the patent achieves control over low viscosity washcoats that would otherwise be difficult to handle. The vacuum application at the lower end creates a controlled suction force that prevents the low viscosity liquid from flowing too quickly or unevenly, maintaining coating uniformity while preserving the handling advantages of low viscosity formulations.
Solution Approach 2:
The vacuum application system provides feedback control over the liquid flow through the channels. By monitoring and controlling the vacuum level at the lower end, the system can adjust the draw force on the liquid washcoat, ensuring uniform coating depth even with low viscosity formulations that are prone to uneven distribution.
3Manufacturing precision
If vacuum is applied at the lower end to draw liquid through channels, then the coating uniformity is improved, but the loss of time increases due to the additional vacuum application step
Solution Approach 1:
The patent enables continuous coating operation by maintaining vacuum application at the lower end throughout the liquid introduction process. The vacuum continuously draws the liquid through the channels as it is being introduced at the upper end, eliminating idle time between liquid introduction and coating formation. This continuous action maintains uniform washcoat distribution while minimizing cycle time.
Solution Approach 2:
The vacuum system is prepared and applied at the lower end before or during the liquid introduction at the upper end. This preliminary preparation of the vacuum field ensures that as soon as the liquid is introduced, it is immediately drawn through the channels with controlled uniformity, reducing the overall coating cycle time while maintaining precision.
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 allows for accurate and uniform coating of filter substrates, reducing batch variability and processing time, while effectively utilizing low viscosity washcoats that are easier to handle and maintain consistent properties.
Implementation Method 1
introducing a pre-determined amount of a liquid into a containment means at an upper end of the filter substrate; coating the channels having open ends at the upper end of the filter substrate with the liquid from the containment means
Implementation Method 2
applying a vacuum to a lower end of the filter substrate to draw the liquid from the containment means along the channels having open ends at the upper end of the filter substrate
Data Source
AI summary
An apparatus of coating a filter substrate comprising a plurality of channels and an apparatus is disclosed. The apparatus comprises: (i) a containment means for receiving a pre-determined amount of the liquid; and (ii) a liquid dosing head arranged to dispense the pre-determined amount of the liquid into the containment means over an upper end of the filter substrate. The containment means is locatable at an upper end of the filter substrate; and the liquid dosing head comprises a plurality of apertures for dispensing the liquid onto the upper end of the filter substrate.