Spring-Biased Damper Flap for Low-Pressure-Drop Extraction Fans
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Solution Overview
Problem
Conventional fan systems allow backdraft of pathogens and reduced efficiency due to inadequate sealing, especially when not running or operating against strong winds, leading to air quality issues and increased energy consumption in animal confinement and other ventilation applications.
Innovation Solution
A damper flap assembly with a pivotally mounted damper flap and spring biasing arrangement that automatically closes when the fan is not running and opens fully or partially when it is, reducing pressure drop and airflow restriction, while maintaining airtightness and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional fan system uses simple louvers without a damper mechanism, then the device complexity is low, but pathogens can enter through the louvers when the fan is closed, compromising air quality and safety
Solution Approach 1:
The fan assembly is segmented into two distinct closure mechanisms: louvers for primary airflow control and a damper flap for secondary sealing. This segmentation allows each component to specialize - louvers handle normal ventilation while the damper flap provides pathogen prevention when closed, resolving the contradiction between simplicity and pathogen protection
Solution Approach 2:
The damper flap acts as an intermediary element between the louvers and the external environment. When louvers are closed, the damper flap provides an additional sealing layer that specifically addresses pathogen infiltration without requiring complete redesign of the louver system, thus adding protection with minimal complexity increase
2Object-affected harmful factors
If a damper flap is added to seal the fan opening when closed, then pathogen prevention improves, but pressure drop increases when the fan is running at full speed
Solution Approach 1:
The damper flap is designed to be dynamic rather than static - it automatically opens when fan-induced airflow exceeds a threshold and closes when airflow decreases. This dynamic behavior allows the system to maintain pathogen prevention when closed while minimizing pressure drop during full-speed operation, as the flap opens to reduce resistance
Solution Approach 2:
The system changes the operational parameter of the damper flap from fixed closed position to variable position based on fan speed and airflow conditions. At low speeds or when stopped, the flap closes for sealing; at high speeds, it opens to reduce pressure drop, thus adapting to different operational requirements and resolving the energy loss contradiction
3Object-affected harmful factors
If the damper flap is held firmly closed to prevent backdraft, then air quality improves, but the fan requires higher power to overcome the sealing resistance when running
Solution Approach 1:
The damper flap transitions from a static firmly-closed state to a dynamic state that responds to airflow forces. When the fan runs at full power, the airflow automatically overcomes the sealing force and opens the flap, reducing resistance and power consumption. This dynamic adjustment resolves the contradiction between maintaining air quality and reducing power requirements
4Loss of energy
If conventional louvers are used without a damper, then the ease of operation is high, but energy consumption increases due to pathogen infiltration requiring additional ventilation
Solution Approach 1:
The damper flap is designed to operate automatically based on airflow conditions without requiring manual intervention or complex control systems. It self-adjusts its position according to fan speed and pressure differential, providing energy efficiency benefits while maintaining operational simplicity, thus resolving the contradiction between energy loss and ease of operation
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 backdraft of pathogens, increases fan efficiency by reducing pressure drop, and decreases energy consumption by allowing for larger fans with fewer units, enhancing air quality and reducing operational costs.
Implementation Method 1
spring biasing arrangement that automatically closes when the fan is not running and opens fully or partially when it is
Implementation Method 2
pivotally mounted damper flap and spring biasing arrangement
Data Source
AI summary
An extraction fan has a housing mounted in a wall with an outlet duct extending through the wall to an outlet opening outside the wall. A damper flap is mounted on the fan suspended by a hinge at an upper edge so as to extend in a closed position across the opening and is movable to an open position under forward air flow from the fan, and tightly closes against a resilient deformable seal when the fan is shut off. A spring biasing cam applies inwards force to the damper flap to bias the damper flap into the closed position, and an outwards force also to bias the damper flap into the fully open position. The mounting plate includes a hood having a top wall extending over the top of the damper flap and a down-turned front flange extending parallel to the damper flap to a bottom edge.