Extractor Hood Guide Vane Layout for Low-Noise Fume Extraction
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Solution Overview
Problem
Extractor hoods with forward-curved centrifugal fans suffer from high noise emissions and large space requirements due to the formation of air vortices and the need for a logarithmically expanding worm housing, which is necessary for building working pressure.
Innovation Solution
Incorporating a preliminary guide grille in the air flow between the fan and the separating element to weaken turbulence and reduce noise, and using a backward-curved radial fan with a larger wheel size to minimize space and power consumption, eliminating the need for a worm housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If forward-curved centrifugal fans are used, then the extractor hood can generate sufficient air flow, but noise emissions increase due to blade rotation sound and vortex formation
Solution Approach 1:
A preliminary guide grille is introduced as an intermediary component between the air intake and the fan. This grille straightens the air flow and reduces turbulence before the air reaches the fan blades, thereby minimizing vortex formation and blade rotation noise while maintaining effective air flow generation.
Solution Approach 2:
The air flow is pre-conditioned by the guide grille before entering the fan. The grille performs preliminary straightening and alignment of air streams, preventing the formation of harmful vortices that would otherwise occur at the fan inlet, thus reducing noise emissions before the air even reaches the rotating blades.
2Stress or pressure
If forward-curved radial fans with worm housing are used, then working pressure can be built up, but the extractor hood requires large installation space
Solution Approach 1:
The logarithmically expanding worm housing is completely removed from the design. Instead of using this space-consuming component to build up working pressure, the invention achieves pressure generation directly through the fan wheel design and the guide grille's flow conditioning, eliminating the need for the worm housing and significantly reducing installation space.
3Volume of stationary object
If housing walls are placed at different distances to save space, then installation footprint is reduced, but strong air vortices and vortex braids form at narrow points
Solution Approach 1:
The preliminary guide grille acts as a mediator between the air intake and the narrow passage between housing walls. It pre-straightens the air flow and prevents the formation of strong vortices that would otherwise occur at the narrow points, allowing compact housing design without suffering from vortex-related noise and efficiency losses.
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 results in significantly reduced noise emissions, effective vapor extraction, and a more compact design, with the extractor hood being quieter and requiring less power than conventional systems while maintaining effective vapor removal.
Implementation Method 1
strong air vortices are also formed, which combine to form so-called vortex braids at the narrowest points. This turbulence hits the rotating impeller blades directly
Implementation Method 2
strong air vortices are also formed, which combine to form so-called vortex braids at the narrowest points
Implementation Method 3
backward-curved radial fan with a larger wheel size to minimize space and power consumption
Data Source
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AI summary
The invention relates to a cooker hood (1) for extracting cooking fumes (2) above a cooktop (3) by means of an airflow (4), comprising a hood housing (5) having at least one air intake opening (6) and at least one air outlet (7) for the airflow (4), at least one fan (8) arranged in the hood housing (5) for generating the airflow (4), and at least one separating element (9) arranged in the hood housing (5) in the airflow (4) between the air intake opening (6) and the fan (8) for separating one or more components of the cooking fumes (2), in particular fat and/or oil, from the airflow (4), wherein the airflow (4) in the hood housing (5) is guided from the air intake opening (6) via the separating element (9) to the fan (8) and is blown out of the hood housing (5) by the fan (8) via the air outlet (7).The object of the invention is to provide an improved extractor hood that enables effective extraction of cooking fumes and offers low noise emissions during operation. Ideally, the extractor hood should also have a small footprint. To this end, the invention proposes that a guide vane (10) be arranged between the fan (8) and the separating element (9) in the airflow (4). This guide vane is designed to split up any swirl tufts forming in the airflow (4) within the extractor housing (5) upon impact with the guide vane (10) and to weaken these swirls as the airflow (4) passes through the guide vane (10).