Backdraft Damper with Opposed-Rotation Blades for Low-Loss Airflow
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Solution Overview
Problem
Conventional backdraft dampers face challenges in maintaining airflow efficiency while preventing backdraft, as the force required to keep blades open reduces airflow and can lead to unintended leakage, and the arrangement of blades can cause turbulence and energy loss.
Innovation Solution
The design incorporates two sets of blades rotating in opposite directions, with one set being more balanced to bias the entire damper to the closed position and the other set being unbalanced to open with low force, creating an intermediate flow region that minimizes obstructions and redirects airflow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If blades are arranged to rotate in opposite directions with differential balancing, then airflow efficiency is improved and energy loss is reduced, but device complexity increases due to the linkage mechanism connecting first and second blades
Solution Approach 1:
The damper blades are segmented into two distinct sets: first blades with counterweights that bias the damper closed, and second blades without counterweights that open more easily. This segmentation allows each set to perform its specific function optimally, reducing overall energy loss while managing the complexity through functional division.
Solution Approach 2:
The patent applies asymmetry by giving first blades and second blades different balancing characteristics. First blades are unbalanced with counterweights to provide closing bias, while second blades are more balanced to open with minimal force. This asymmetric design optimizes airflow efficiency and reduces energy loss.
2Reliability
If blades are biased to closed position by gravity through counterweights, then backdraft prevention is improved, but airflow efficiency deteriorates due to reduced force required to keep blades open
Solution Approach 1:
The damper is segmented into first blades equipped with counterweights for reliable backdraft prevention, and second blades without counterweights that require minimal force to open. This segmentation resolves the contradiction by assigning different functions to different blade sets, ensuring both reliable backdraft prevention and maintained airflow efficiency.
Solution Approach 2:
Different blade sets have different local qualities regarding their balancing. First blades have heavy counterweights for reliable closing, while second blades have minimal counterweighting for easy opening. This local differentiation allows the system to achieve both reliable backdraft prevention and good airflow efficiency simultaneously.
3Productivity
If intermediate flow region is created by opposing blade rotation, then airflow efficiency is improved by minimizing obstructions, but device complexity increases due to linkage mechanism
Solution Approach 1:
The blade system is segmented into first and second sets that rotate in opposite directions, creating an intermediate flow region. This segmentation strategy improves airflow efficiency by minimizing obstructions in the central flow path, while the complexity is managed through functional specialization of each blade set.
Solution Approach 2:
The linkage mechanism acts as an intermediary that connects the first and second blades, coordinating their opposite rotations to create the intermediate flow region. This intermediary mechanism enables the airflow efficiency improvement while centralizing the complexity in a single coordinating component rather than requiring complex individual blade mechanisms.
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
This configuration enhances airflow efficiency by reducing energy loss and maintaining the damper in the open position with minimal backpressure, while ensuring the blades close automatically under gravity, thus preventing backdraft without sacrificing airflow.
Implementation Method 1
the one or more first blades being more balanced about respective pivot members than the one or more second blades thereby to permit the one or more first blades to bias the entire plurality of blades to the closed position
Implementation Method 2
movable to the open position by the force of air flowing through the frame in the outflow direction
Data Source
AI summary
A backdraft damper for permitting a flow of air in an outflow direction and preventing the flow of air in a backdraft direction, including a frame having a transverse opening allowing the passage of air through the frame; a plurality of blades, each blade extending across the frame and mounted to the frame about a central portion by pivot members, for rotation between an open position in which the blade allows air to flow through the frame and a closed position in which the blade blocks air from flowing through the frame, the plurality of blades including one or more first blades arranged to rotate in a first direction from the closed position to the open position; one or more second blades arranged to rotate in a second direction opposite to the first direction from the closed position to the open position; the backdraft damper further including a linkage between the one or more first blades and the one or more second blades to cause the first and second blades to together rotate between the closed and open positions; and the one or more second blades being more balanced about respective pivot members than the one or more first blades thereby to permit the one or more first blades to bias the entire plurality of blades to the closed position while being movable to the open position by the force of air flowing through the frame in the outflow direction.