Blower and a blower diffuser
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Solution Overview
Problem
Existing back draft dampers with butterfly valves in ventilation systems do not completely close the ducts, leading to inefficiencies in back draft resistance, requiring additional gaskets for effective closure.
Innovation Solution
A diffuser design with a butterfly valve where the hinge axes intersect the diffuser shroud closer to the upstream side, allowing gravity to operate the doors for closure, and semi-elliptical door plates with straight edges that form a complete ellipse in the closed position, minimizing airflow resistance when active and providing efficient back draft resistance when inactive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional butterfly valves are used in diffusers, then the valve structure is simple, but the doors cannot completely close the diffuser opening, requiring additional gaskets for effective back draft resistance
Solution Approach 1:
The hinge axes are positioned asymmetrically closer to the upstream side of the diffuser shroud rather than at the center or downstream side. This asymmetric positioning allows the gravity-operated doors to achieve complete closure against the diffuser opening, eliminating the need for additional gaskets while maintaining structural simplicity
Solution Approach 2:
The butterfly valve doors are designed to be gravity-operated, automatically closing when the blower is inactive and opening when active. The asymmetric hinge positioning enables the doors to self-close completely without requiring additional sealing components, making the system self-sufficient for back draft prevention
2Reliability
If the hinge axes are positioned closer to the upstream side, then the doors can completely close the diffuser opening, but the hinge arrangement becomes more complex
Solution Approach 1:
The hinge axes are positioned asymmetrically closer to the upstream side of the diffuser shroud. This asymmetric configuration enables complete door closure by leveraging gravity to pull the doors against the diffuser opening, achieving reliable sealing without requiring complex additional mechanisms
3Productivity
If the doors are designed with straight edges forming a complete ellipse, then airflow resistance is minimized, but the manufacturing precision requirements increase
Solution Approach 1:
The door plates are designed as semi-elliptical shapes with curved surfaces instead of flat or angular geometries. When closed, the two semi-elliptical doors form a complete ellipse that closely matches the diffuser opening contour. This curved geometry minimizes turbulence and airflow resistance while the elliptical shape is achievable through standard manufacturing processes
Solution Approach 2:
The door plates feature straight edges at specific locations where they abut each other to form the dividing line corresponding to the major axis of the ellipse. This localized straight edge feature provides a precise mating surface for complete closure, while the overall semi-elliptical shape maintains smooth airflow characteristics
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 design ensures minimal airflow resistance during operation and effective back draft resistance without the need for additional gaskets, enhancing the efficiency of back draft closure and reducing airflow resistance.
Implementation Method 1
the doors of the butterfly valve are gravity operated so that they are urged by the gravity to their closed position when the blower is not activated
Data Source
AI summary
A diffuser arranged at the downstream side of a blower, the diffuser including a conical diffuser shroud with a back draft damping butterfly valve arranged in the diffuser opening, and where the butterfly valve includes two doors both being attached to the diffuser shroud via a hinge arrangement adapted for allowing each of the two doors to rotate between a closed and an open position about the hinge axes extending between opposite sides of the diffuser shroud and where the doors are shaped so that they together substantially close the diffuser opening when they are in their closed position, and wherein each hinge axis intersects the diffuser shroud at a position closer to the upstream side at one side than on the opposite side of the diffuser shroud.