Washcoat Showerhead Pressure Drop to Prevent Substrate Coating Drips
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Solution Overview
Problem
Existing methods for coating substrates used in exhaust gas purification face issues such as uneven washcoat profiles, washcoat dripping or leakage, and excessive application, leading to reduced operational efficiency and wastage, which can block passage openings and cause visual degradation.
Innovation Solution
A substrate coating apparatus and method that utilizes a valve assembly with a valve stem and seat configuration to create a pressure drop within the washcoat showerhead, reducing or preventing dripping and leakage by generating a suction force at the apertures, ensuring even washcoat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If washcoat is applied to the substrate using conventional methods, then the substrate receives coating, but washcoat dripping and leakage occur leading to uneven profiles and blockages
Solution Approach 1:
The patent applies pneumatic principles by using a vacuum source connected to the substrate to create a pressure differential during washcoat application. The vacuum pulls the washcoat through the substrate uniformly, preventing dripping and leakage. This pneumatic control mechanism ensures precise washcoat distribution and eliminates the harmful dripping effect that occurs with conventional gravity-based application methods.
Solution Approach 2:
The patent implements preliminary action by applying vacuum to the substrate before washcoat application begins. This pre-established pressure differential ensures that as soon as washcoat contacts the substrate, it is immediately and uniformly drawn through the passages, preventing accumulation and dripping on the substrate surface. The preliminary vacuum preparation eliminates the need for subsequent correction of uneven profiles.
2Quantity of substance
If washcoat is applied with high volume to ensure complete coverage, then coverage is improved, but excessive washcoat causes blockages and wastage
Solution Approach 1:
The vacuum-assisted application system controls washcoat flow rate by regulating the pressure differential between the atmosphere and the vacuum source. This pneumatic control ensures that only the precise amount of washcoat needed to fill the substrate passages is applied, preventing both under-coverage and over-application. The system automatically adjusts washcoat uptake to match substrate capacity, eliminating wastage.
Solution Approach 2:
The system incorporates feedback through the vacuum pressure sensor that monitors the pressure differential during washcoat application. As washcoat fills the substrate passages, the vacuum pressure changes, providing real-time feedback on the coating progress. This feedback mechanism automatically modulates washcoat flow to stop precisely when passages are filled, preventing excessive application and associated wastage.
3Productivity
If conventional valve closure methods are used, then washcoat flow is stopped, but residual washcoat continues to drip from the showerhead
Solution Approach 1:
The system applies preliminary vacuum to the showerhead and delivery system before washcoat flow stops. This pre-established negative pressure immediately draws back any residual washcoat in the delivery lines and prevents it from dripping at the showerhead after valve closure. The preliminary vacuum action ensures clean shutdown without residual dripping that would compromise the coating quality.
Solution Approach 2:
The vacuum pressure acts as a counterbalancing force to the gravitational force that causes washcoat dripping. By maintaining negative pressure in the delivery system after valve closure, the vacuum creates an upward force that counteracts gravity's pull on residual washcoat, preventing it from dripping down the showerhead. This force balance eliminates the harmful dripping effect.
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 mitigates washcoat dripping and leakage, achieving a uniform washcoat profile and preventing blockages, thereby enhancing operational efficiency and reducing wastage.
Implementation Method 1
the valve assembly is configured to create a pressure drop within an interior of the washcoat showerhead when the outlet valve moves from its open state to its closed state
Implementation Method 2
The pressure drop within the interior of the washcoat showerhead may act to create a suction force which reduces or prevents dripping or leakage of the washcoat
Data Source
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AI summary
Apparatus and method for coating substrates with washcoats in which a substrate (10) is engaged with a headset (6) of a substrate coating apparatus (1) below a washcoat showerhead (5). Washcoat is discharged from the washcoat showerhead (5) onto an upper surface (12) of the substrate under control of a valve assembly (4) before being drawn through the substrate by use of a vacuum generator (7). The valve assembly (4) comprises an outlet valve movable between a closed state and an open state. The valve assembly (4) creates a pressure drop within an interior of the washcoat showerhead (5) when the outlet valve moves from its open state to its closed state. This prevents dripping of washcoat from the washcoat showerhead (5) after the valve assembly has been closed.