Spring-Biased Fan Damper Assembly for Backdraft and Pressure Drop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fan louvers in animal confinement and other ventilation systems fail to prevent backdraft and infiltration of airborne pathogens, especially when not running or operating at low speeds, leading to potential disease transmission and reduced efficiency due to pressure drop issues.
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 operating, using a resilient seal and optional solenoid for enhanced sealing and airflow management, effectively preventing backdraft and reducing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damper flap is provided to prevent backdraft when the fan is not running, then pathogen infiltration is prevented, but the device complexity increases
Solution Approach 1:
The damper flap assembly is designed to automatically close when the fan stops running and automatically open when the fan starts, using the fan's own operation to trigger the damper action. The spring biasing arrangement provides automatic operation without external control systems, making the system self-regulating and eliminating the need for additional actuators or control mechanisms.
Solution Approach 2:
The damper flap assembly is extracted as a separate, modular unit that can be independently installed on the fan housing. This modular approach allows the backdraft prevention function to be added without redesigning the entire fan system, thereby limiting the increase in overall device complexity while still achieving reliable backdraft control.
2Productivity
If the damper flap is held fully open to reduce pressure drop when the fan runs at full speed, then airflow restriction is minimized, but backdraft control is compromised when the fan is not running
Solution Approach 1:
The damper flap is designed to be dynamic rather than static, automatically adjusting its position based on fan operation status. It transitions between fully closed (when fan is off) and fully open (when fan is running), optimizing both backdraft prevention and airflow efficiency at different operational states without requiring manual intervention or complex control systems.
Solution Approach 2:
The spring biasing arrangement is pre-configured to automatically close the damper flap before any backdraft can occur when the fan stops. This preliminary action ensures that the damper is already in the closed position to prevent backdraft infiltration before negative pressure develops in the building, while the same spring mechanism readily allows the flap to open when the fan starts to prevent airflow restriction.
3Reliability
If a resilient seal is added to achieve hermetic sealing, then backdraft control is improved to almost 100%, but manufacturing complexity increases
Solution Approach 1:
A resilient deformable seal is incorporated between the damper flap and the mounting plate flange to achieve hermetic sealing. The flexible seal material deforms under pressure to create an airtight barrier, preventing even small amounts of backdraft infiltration. This approach achieves almost 100% sealing effectiveness while remaining relatively simple to manufacture and install compared to rigid sealing systems.
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 almost 100% backdraft control, reduces pathogen infiltration, and increases fan efficiency by minimizing airflow restriction, allowing for reduced fan usage and energy consumption while maintaining airtightness and easy installation.
Implementation Method 1
a spring biasing arrangement arranged for applying force to the damper flap, the spring biasing arrangement being arranged on one side of a partially open position to bias the damper flap into the closed position and on an opposed side of the partially open position to bias the damper flap into the fully opened position
Implementation Method 2
a resilient deformable seal between the outer peripheral portion of the damper flap and the flange arranged to seal the damper flap to prevent reverse flow of air through the fan housing when the fan is not running
Implementation Method 3
the damper flap is suspended by a hinge at an upper edge and pivotal about the upper edge to utilize gravity in the closing action
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.