Gravity Exhaust Air Shutter Assembly to Prevent Backdraft Leakage
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Solution Overview
Problem
Existing air handling systems, such as packaged air-conditioning units, suffer from outside air leakage through louvered slats, which degrades their performance and efficiency.
Innovation Solution
A gravity exhaust air shutter assembly with a shutter flap and open frame configuration, utilizing a gasket for sealing and controlled by exhaust fans to prevent backdraft and leakage, ensuring zero leakage by gravity and negative pressure when fans are off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If louvered slats are used for exhaust opening, then exhaust fans can discharge return air, but outside air leaks into the unit through the louvered slats
Solution Approach 1:
The shutter assembly uses a movable shutter blade that can dynamically transition between open and closed positions based on operational requirements. When exhaust fans are active, the blade opens to allow discharge; when inactive, it closes to prevent outside air leakage, thus adapting the system's state to current operational conditions
Solution Approach 2:
The shutter blade is designed to automatically open and close based on pressure differential created by exhaust fan operation, without requiring external control mechanisms. The system uses its own operational state (fan-induced pressure changes) to trigger the shutter's movement, making the shutter self-regulating
2Object-affected harmful factors
If shutter blade is held closed by gravity and negative pressure, then outside air leakage is prevented, but exhaust air cannot be discharged when fans are on
Solution Approach 1:
The system changes the pressure parameter (from negative to positive) to control shutter blade position. During normal operation, negative pressure keeps the blade closed for sealing. When exhaust fans activate, they create positive pressure that overcomes the sealing force and opens the blade, thus using parameter change to switch between sealing and discharge modes
Solution Approach 2:
The gasket is applied specifically at the interface between the shutter blade and frame where sealing is critical, providing localized sealing quality only where needed. This allows the blade to remain lightweight and easy to move while achieving effective sealing at the critical junction point
3Object-affected harmful factors
If gasket is used to seal between shutter blade and frame, then outside air leakage is reduced, but device complexity increases
Solution Approach 1:
The gasket is a simple, inexpensive sealing component that can be easily replaced if needed. Using a simple gasket rather than a complex mechanical sealing system reduces overall device complexity while still achieving the sealing objective. The gasket acts as a low-cost, easily maintainable sealing solution
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 prevents outside air from entering the system, enhancing the performance and efficiency of air handling systems by ensuring a tight seal, even under high negative pressure conditions.
Implementation Method 1
A gravity exhaust air shutter assembly with a shutter flap and open frame configuration, utilizing a gasket for sealing and controlled by exhaust fans to prevent backdraft and leakage, ensuring zero leakage by gravity and negative pressure when fans are off
Implementation Method 2
Operation of the one or more exhaust fans creates a positive air pressure after the fans that lifts the shutter flap from the closed to the open position
Implementation Method 3
Mounted around the perimeter of the frame on the side adjacent to the shutter flap is a gasket. The gasket may be a closed cell material. The shutter flap contacts the gasket when the shutter flap is in the closed position thereby creating a seal between the shutter flap and the open frame
Implementation Method 4
the higher the negative pressure, the better the seal that is formed, as the shutter flap continues to be drawn against the gasket
Data Source
AI summary
An exhaust air shutter assembly may include a housing having a dividing wall separating the exhaust air shutter assembly into an inside portion and an outside portion. An opening may be formed in the dividing wall and a frame may be mounted around the perimeter of the hole. Disposed on the frame may be a gasket that extends around the entire perimeter of the hole. The exhaust air shutter also may include at least one shutter flap mounted adjacent to the frame with a hinge such that the shutter flap can pivot between a closed position and an open position. When the shutter flap is in the open position, an air flow path exists from the inside portion of the exhaust air shutter assembly to the outside portion. When the shutter flap is in the closed position the air flow path is blocked. The shutter flap is configured to contact the gasket mounted to the frame when the shutter flap is in the closed position, thereby creating a seal between the shutter flap and the opening in the dividing wall.