Oven Fume Extraction Duct With Centrifugal Impeller and Door Cooling
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Solution Overview
Problem
Existing cooking appliances face inefficiencies due to the distant positioning of the flue outlet relative to the tangential fan, leading to reduced fume extraction efficiency, increased material usage, and complex assembly processes, as well as inadequate cooling of the oven door.
Innovation Solution
A cooking appliance design featuring a radial fan with a centrifugal impeller positioned within the duct body, allowing for direct fume extraction and reduced duct body length, along with a tapered duct body shape and flow-deflector element for improved airflow, enabling smaller fume outlet sizes and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a tangential fan is positioned at a distance from the flue outlet, then the fan can draw air from behind the muffle, but the fume extraction efficiency decreases and the fume outlet hole must be larger causing heat dispersion
Solution Approach 1:
A radial fan with centrifugal impeller is introduced as an intermediary device between the flue outlet and the delivery channel. This fan creates a volute that directs fumes from the flue outlet through an intake channel to the delivery channel, enabling efficient fume extraction while maintaining the ability to draw cooling air from behind the muffle through a separate path.
Solution Approach 2:
The air intake system is segmented into two separate pathways: one for fume extraction through the radial fan and volute, and another for cooling air intake from behind the muffle. This segmentation allows each pathway to be optimized independently, maintaining high fume extraction efficiency while ensuring adequate cooling air supply.
2Productivity
If the duct body extends from the rear area to the front of the appliance, then delivery is achieved, but material usage increases and assembly becomes more complex
Solution Approach 1:
The radial fan housing is merged with the duct body structure, forming an integrated assembly. The volute of the radial fan is positioned within the duct body, eliminating the need for separate extensive ductwork from rear to front. This merging reduces material usage and simplifies assembly while maintaining effective fume delivery to the front of the appliance.
3Productivity
If the fume outlet hole is made larger to compensate for distant fan positioning, then fume extraction is maintained, but heat dispersion increases
Solution Approach 1:
The radial fan with centrifugal impeller acts as an intermediary that creates a controlled flow path through the volute and intake channel. This allows the fume outlet hole to be smaller while maintaining extraction efficiency, as the fan generates the necessary suction and directs fumes through a confined path, reducing heat dispersion compared to larger open outlets.
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 design enhances fume extraction efficiency, allows for the installation of a filtering element, reduces material and assembly complexity, and improves cooling of the oven door through direct airflow and reduced temperature.
Implementation Method 1
a radial fan with a centrifugal impeller inside the duct body, the centrifugal impeller being positioned above the fume inlet of the duct body substantially coaxial thereto and to the fume outlet of the muffle in such a way that at least the fumes are drawn in from the fume outlet substantially in the direction of the axis of the impeller and forced in a radial direction into the delivery channel
Implementation Method 2
provided inside the duct body, within the delivery channel, is a flow-deflector element configured for rendering the flow forced by the centrifugal impeller into the delivery channel uniform
Implementation Method 3
the duct body preferably having a shape generally tapered towards its rear end region
Data Source
AI summary
A household cooking appliance, in particular an oven, comprises a cooking chamber defined by a muffle having a flue with a fume outlet at an upper wall of the muffle, and a front door, for opening and closing the cooking chamber. The appliance further comprises a delivery channel, defined by a duct body that extends above the upper wall of the muffle, the duct body having an outlet of the delivery channel that is substantially at a front region of the appliance, above an upper portion of the door, and having a fume inlet in a lower wall of the duct body, which is in fluid communication with the fume outlet of the muffle and with the delivery channel. Operatively associated to the duct body is a ventilation assembly, so as to draw in fumes from the fume outlet of the muffle and expel them from the outlet of the delivery channel, the ventilation assembly being in a rear end region of the duct body that is generally opposite to the outlet of the delivery channel. The ventilation assembly comprises a radial fan with a centrifugal impeller inside the duct body, the centrifugal impeller being positioned above the fume inlet of the duct body substantially coaxial thereto and to the fume outlet of the muffle in such a way that at least the fumes are drawn in from the fume outlet substantially in the direction of the axis (X) of the impeller and forced in a radial direction into the delivery channel for being expelled from the corresponding outlet. The rear end region of the duct body has a generally rounded peripheral profile so as to form a volute of the radial fan, the duct body preferably having a shape generally tapered towards its rear end region and comprising a lower half-shell and an upper half-shell. Provided inside the duct body, within the boundaries of the delivery channel, is a flow-deflector element configured for rendering the flow forced by the centrifugal impeller into the delivery channel uniform.