Spherical-Ball Backdraft Damper for Airtight Backflow Prevention
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Solution Overview
Problem
Existing self-sealing back draft dampers for ventilation systems, such as exhaust fans and extractor hoods, often have design flaws that lead to unwanted backflow of air and moisture due to gaps between movable and non-moving parts, requiring precise adjustments and increased dimensions, which complicates mounting and airflow.
Innovation Solution
A self-sealing back draft damper with a conical tapered tube and a spherical closing member that self-positions at the narrow end to prevent backflow, eliminating the need for precise adjustments and allowing for easy mounting and increased airflow without extensive size increases, using a hollow body with a frustoconical shape and inclined axis for effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional butterfly valves, throttle valves, or slats are used as back draft dampers, then the device structure is simple, but gaps appear between movable parts and nonmoving sections leading to air backflow
Solution Approach 1:
The patent employs a spherical closing member (ball) that rolls within a cylindrical valve body to achieve sealing. The spherical shape allows the ball to conform to the circular cross-section of the duct, creating an airtight seal against the valve body wall without requiring precise gaps or additional gaskets. This curvature-based approach resolves the contradiction by providing reliable sealing through geometric conformity rather than complex mechanical adjustments.
Solution Approach 2:
The valve body is segmented into a cylindrical section and a conical tapered section, with the spherical closing member operating independently within the cylindrical portion. This segmentation allows the ball to seal against the cylindrical wall while the conical section provides structural support and mounting functionality, separating the sealing function from the structural function to achieve both simplicity and reliability.
2Reliability
If ball check valves with valve bodies and additional closing parts are used, then sealing is improved, but precise adjustment between dimensions is required which complicates mounting
Solution Approach 1:
The patent changes the geometric parameters of the closing member and valve body to eliminate the need for precise dimensional adjustments. By using a spherical ball with diameter comparable to but not smaller than the inner diameter of the conical tapered tube, and a cylindrical valve body with sufficient length, the system achieves sealing through geometric relationships rather than precise dimensional matching. This parameter optimization allows universal mounting without adjustment.
Solution Approach 2:
The spherical closing member automatically positions itself within the cylindrical valve body through its own weight and the geometry of the conical tapered section, achieving self-alignment and self-sealing. The ball rolls to the appropriate position where it contacts the valve body wall to prevent backflow, eliminating the need for manual adjustment or precise pre-positioning during mounting.
3Productivity
If larger inlet dimensions are used to enable optimal airflow, then airflow performance is improved, but the overall dimensions of the check valve increase leading to unhandy mounting
Solution Approach 1:
The spherical closing member enables efficient airflow through a compact cylindrical valve body by creating a clean, gap-free seal that minimizes flow resistance. The spherical shape allows the ball to seal effectively against the circular duct wall without requiring oversized inlet dimensions, maintaining optimal airflow while keeping the valve compact and easy to mount.
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 provides a reliable, cost-effective, and easy-to-mount device that completely prevents backflow, ensuring an airtight seal and allowing for self-initiated ventilation, even under weak airflow conditions, effectively addressing the issue of odor and moisture ingress in residential spaces.
Implementation Method 1
The weight of the spherical closing member and the slope of the tapered tube are such that in absence of airflow in the direction to the exit opening of the valve, the closing member is self-positioned at the conical tapered inlet
Implementation Method 2
the spherical closing member can overcome the inclination on its path and is away from the inlet under force directed to the vent resulting from a pressure difference appearing between the exit openings and the inlet
Implementation Method 3
A self-sealing back draft damper for a complete prevention of backflow air... providing an airtight seal against unwanted backflow
Data Source
AI summary
A self-sealing back draft damper for fully stopping backflow air through exhaust fans and extractor hoods. Contains a housing (1), with exit openings (2) and can have at least one mounting hole (10). Inside the housing (1) at least one inclined relative to the horizontal plane conical tapered tube (3) is airtightly fixed at its lower positioned narrow end to the hole (10), forming the conical tapered inlet (6) of the damper. Apertures are available on the tube part inside the housing. The tube (3) contains a spherical closing member (5) freely movable inside it, which closes the conical tapered inlet (6) and opens it when pushed away by airflow in direction to the vent. The axis of the tapered tube (3) can be also vertically oriented. The damper is airtightly attached preferrably to the entrance of a fan, to the exhaust of an extractor hood or a vent.