EP4184064A1 - Abzugseinheit - Google Patents

Abzugseinheit Download PDF

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Publication number
EP4184064A1
EP4184064A1 EP22207719.0A EP22207719A EP4184064A1 EP 4184064 A1 EP4184064 A1 EP 4184064A1 EP 22207719 A EP22207719 A EP 22207719A EP 4184064 A1 EP4184064 A1 EP 4184064A1
Authority
EP
European Patent Office
Prior art keywords
outlet
casing
height
impeller
ending
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22207719.0A
Other languages
English (en)
French (fr)
Inventor
Giannetto BIAGINI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BS Service Srl
Original Assignee
BS Service Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BS Service Srl filed Critical BS Service Srl
Publication of EP4184064A1 publication Critical patent/EP4184064A1/de
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/20—Removing cooking fumes
    • F24C15/2042—Devices for removing cooking fumes structurally associated with a cooking range e.g. downdraft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
    • F04D29/4226—Fan casings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/20—Removing cooking fumes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/70—Suction grids; Strainers; Dust separation; Cleaning
    • F04D29/701—Suction grids; Strainers; Dust separation; Cleaning especially adapted for elastic fluid pumps
    • F04D29/703—Suction grids; Strainers; Dust separation; Cleaning especially adapted for elastic fluid pumps specially for fans, e.g. fan guards
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/50—Inlet or outlet
    • F05D2250/52—Outlet

Definitions

  • the present invention relates to an extractor unit, specifically to a centrifugal electric fan for household appliances, such as extractor hoods.
  • Extractor units are known in the household appliance industry for being used in extractor hoods disposed above the cooktop and in extractor hoods integrated under the cooktop. In each case, said extractor units are employed to evacuate fumes from the cooktop.
  • Such an extractor unit comprises a centrifugal fan having a squirrel-cage impeller with forward curved blades, which is rotatably mounted in a stator casing with a substantially cylindrical development. Sections that are basically identical to each other are obtained by intersecting the casing of the fan with a bundle of parallel planes perpendicular to the axis of the impeller. The main plane is the plane that passes at mid-height of the blades of the impeller.
  • a centrifugal fan has an inlet (extraction) disposed axially in the casing and an outlet (delivery) disposed laterally in the casing.
  • the extractor unit (200) comprises an impeller (1), rotatably mounted in a casing (2) so as to rotate about an axis (X).
  • the impeller (1) is a cylindrical squirrel-cage impeller with forward curved blades.
  • the casing (2) is in the shape of a receptacle including a central portion (20) of basically cylindrical shape, wherein the impeller (1) is rotatably mounted.
  • the central portion (20) of the casing is not cylindrical, but has a spiral shape (logarithmic spiral profiles are known in the literature).
  • the casing (2) comprises an inlet (3) to extract the air and an outlet (4) to eject the extracted air.
  • the inlet (3) is a circular opening that is disposed axially in the central portion (20) of the casing.
  • the inlet (3) is normally covered by a grille (5).
  • the outlet (4) is a conduit or a coupling that protrudes laterally from the central portion (20) of the casing.
  • the outlet (4) has an inlet section (40) that is connected to the central portion (20) of the casing and an outlet section (41) that is suitable for being coupled with a connection of an extraction pipe or conduit of an air extraction system.
  • the outlet (4) has an ending portion (6) and a coupling portion (7) disposed between the central portion (20) of the casing and the ending portion (6) of the outlet.
  • the coupling portion (7) is disposed between the inlet section (40) and an intermediate section (42).
  • the ending portion (6) is disposed between the intermediate section (42) and the outlet section (41).
  • Figs. 1 to 5 show an extractor unit (200) with rectangular outlet (4).
  • the ending portion (6) of the outlet must have standardized dimensions in order to be coupled with a standard connection of an air extraction pipe with rectangular section. Therefore, the intermediate section (42) and outlet section (41) of the ending portion (6) of the outlet have the same rectangular dimensions.
  • the outlet section (40) of the outlet (4) has a height (H) of 99 mm and a width (W) of 219 mm. These dimensions are constant throughout the ending portion (6) of the outlet.
  • the entire outlet (4) has a constant height (H) from the inlet section (40) to the outlet section (41); otherwise said, the ending portion (6) and the coupling portion (7) have the same height (H).
  • the central portion (20) of the casing has a height (H1) that is substantially equal to the height (H) of the outlet (4).
  • the fluid inside the casing (2) is subjected to a dynamic pressure and to a static pressure.
  • the energy transmitted to the fluid by the impeller (1) has a kinetic component due to the dynamic pressure and a static component due to the static pressure.
  • the kinetic component is greater than the static component.
  • the kinetic component is smaller than the static component.
  • Profiles of the central portion (20) of the spiral-shaped casing obtained by connecting a plurality of arcs of circumferences having centers at different positions and different radii of curvature are known.
  • profiles of the central portion (20) of the casing obtained by means of mathematical functions, such as logarithmic spiral or the like are known.
  • the coupling portion (7) of the outlet comprises:
  • the outlet surface (So) In order to achieve a fluid expansion, the outlet surface (So) must be greater than the inlet surface (Si). According to the prior art, such a geometric relationship is obtained because the width (W) of the outlet surface (So) is greater than the width (Wi) of the inlet surface (Si). Instead, the heights (H) of the inlet surface and of the outlet surface are equal.
  • the width (W) of the outlet surface (So) is approximately twice the width (Wi) of the inlet surface (Si). Therefore, the outlet surface (So) is approximately twice as large as the inlet surface (Si), thus ensuring a fluid expansion.
  • the length (L) of the coupling portion (7) is limited, such a length (L) being approximately 20-40 mm.
  • the increase in the width of the coupling portion (7) is not symmetrical, and occurs only in one side of the coupling portion. These factors create an abrupt (not gradual) expansion of the fluid flow in the coupling portion. Such abrupt expansion of the fluid creates the detachment of the fluid flow, with the formation of vortexes that induce pulsations of fluid velocity fields and pressures, resulting in higher noise emissions and lower efficiency and performance of the extractor unit.
  • Figs. 7 and 8 show bidimensional examples of flow, respectively on cross-sections and on planes orthogonal to the axis of the impeller, wherein the outlet (4) of the extractor unit is coupled to an extraction pipe (8).
  • Both figures show the formation of vortices (F1, F2) in the extraction pipe (8) near the outlet section (41) of the outlet of the extractor unit.
  • the vortices (F1, F2) have axes parallel to the axis (X) of the impeller (1).
  • Fig. 9 shows a bidimensional example of flow on an axial section on a meridian plane whereon the axis of the impeller lies, wherein the outlet (4) of the extractor unit is coupled to the extraction pipe (8).
  • Fig. 9 shows the formation of first vortices (F3) coming out of the impeller and of second vortices (F4) in the extraction pipe (8).
  • Said vortices (F3, F4) have axes orthogonal to the meridian plane whereon the axis (X) of the impeller lies.
  • the first vortices (F3) are due to the non-uniform distribution of the velocities coming out of the single blade of the impeller.
  • the flow velocities will increase on any meridian plane from the inlet (3) to the base of the impeller (1).
  • EP3620721 describes an extractor unit according to the preamble of independent claim 1.
  • Such an extractor unit comprises a casing and an impeller, rotatably mounted in a central portion of the casing.
  • the casing comprises an inlet for extracting a fluid and an outlet for delivering the extracted fluid.
  • the impeller is a cylindrical impeller with backward curved blades relative to the rotational direction of the impeller.
  • Such an impeller with backward curved blades is impaired by the fact that a high noise is produced.
  • the impeller with backward curved blades has a small number of large blades, i.e. blades with a high radial extension (difference between the outer diameter and the inner diameter of the impeller).
  • an impeller with forward curved blades has a large number of small blades, i.e. blades with a small radial extension.
  • the purpose of the present invention is to eliminate the drawbacks of the prior art by providing an extractor unit that is capable of guaranteeing a gradual control of the fluid flow along the outlet of the extractor unit without having to excessively modify the dimensions of the ending portion of the outlet.
  • Another purpose of the present invention is to provide such an extractor unit that is noiseless and efficient.
  • Still another purpose of the present invention is to provide such an extractor unit provided with an ending portion of the outlet that is suitable for being coupled with standard connections of extraction pipes.
  • the extractor unit (100) has a casing (2) comprising:
  • the air is extracted axially from the inlet (3) into the central portion (20) of the casing, is ejected radially from the impeller (1), and is conveyed towards the outlet (4).
  • the impeller (11) is a cylindrical squirrel-cage impeller with forward curved blades.
  • the central portion (20) of the casing is substantially shaped like a cylindrical receptacle, preferably having a spiral-shaped section along a plane orthogonal to the axis of the impeller.
  • the outlet (4) comprises:
  • the coupling portion (7) is disposed between an inlet section (40) connected to the central portion (20) of the casing and an intermediate section (42) connected to the ending portion (6) of the outlet.
  • the ending portion (6) is disposed between the intermediate section (42) and an outlet section (41) consisting of an ending edge of the ending portion (6).
  • the ending portion (6) has a rectangular section having a suitable height (H) and a suitable width (W) in such a way to be coupled with a connection of an extraction pipe.
  • the coupling portion (7) has a tapered shape in the width direction, with increasing width going from the inlet section (40) to the intermediate section (42).
  • the central portion (20) of the casing has a height (H1) greater than the height (H) of the ending portion (6) of the outlet. Consequently, the coupling portion (7) has a tapered shape in the height direction, with decreasing height going from the inlet section (40) to the intermediate section (42).
  • Such a decreasing tapering in the height direction avoids an abrupt expansion of the fluid and instead generates a gradual expansion of the fluid in the coupling portion (7), preventing the formation of turbulence and vortexes.
  • the inlet section (40) between the central portion (20) of the casing and the coupling portion (7) has a height (Hi) equal to the height (H1) of the casing.
  • the intermediate section (42) between the coupling portion (7) and the ending portion (6) has a height (H) equal to the height (H) of the ending portion.
  • the intermediate portion (7) of the outlet has the inlet section (40) of rectangular shape with an inlet surface (Si) and the intermediate section (41) of rectangular shape with an outlet surface (So).
  • the inlet surface (Si) has a height (Hi) and a width (Wi).
  • the outlet surface (So) has a height (H) and a width (W).
  • the height (Hi) of the inlet surface (Si) is greater than the height (H) of the outlet surface (So) (i.e. Hi > H) and, as in the prior art, the width (W) of the outlet surface (So) is greater than the width (Wi) of the inlet surface (i.e. W > Wi).
  • the outlet surface (So) In each case, in order to achieve a fluid expansion, the outlet surface (So) must be greater than the inlet surface (Si). Therefore, the difference between the width (W) of the outlet surface (So) and the width (Wi) of the inlet surface must be greater than the difference between the height (Hi) of the inlet surface (Si) and the height (H) of the outlet surface (So). That is to say, the following relationships must be satisfied: W ⁇ Wi > Hi ⁇ H Hi > H W > Wi
  • the height (H1) of the central portion (20) of the casing that is equal to the height (Hi) of the inlet section (40) must be 120-150% of the height (H) of the ending portion (6) of the outlet.
  • the width (Wi) of the inlet section (40) must be 40-60% of the width (W) of the ending portion (6) of the outlet.
  • the height (H) of the ending portion (6) of the outlet has the standardized dimension of 99 mm
  • the height (H1) of the central portion (20) of the casing must be comprised between 120 mm and 150 mm.
  • the coupling portion (7) has a length (L) that must be limited because of space issues.
  • the length (L) of the coupling portion (7) can be 20-40 mm.
  • the height (H1) of the central portion (20) of the casing is selected so that a gradual flow variation can be obtained in the short length of the coupling portion (7).
  • Fig. 16 shows a two-dimensional example of flow on an axial section on a meridian plane whereon the axis of the impeller (1) lies, wherein the outlet (4) of the extractor unit is coupled to an extraction pipe (8).
  • Fig. 16 shows a regular flow (F5) in the coupling portion (7), without creating any vortexes in the extraction pipe (8).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Extraction Or Liquid Replacement (AREA)
EP22207719.0A 2021-11-19 2022-11-16 Abzugseinheit Pending EP4184064A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT202100029375 2021-11-19

Publications (1)

Publication Number Publication Date
EP4184064A1 true EP4184064A1 (de) 2023-05-24

Family

ID=80121937

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22207719.0A Pending EP4184064A1 (de) 2021-11-19 2022-11-16 Abzugseinheit

Country Status (1)

Country Link
EP (1) EP4184064A1 (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2738394A1 (de) * 2012-11-29 2014-06-04 BSH Bosch und Siemens Hausgeräte GmbH Gehäuse für ein Radialgebläse und Radialgebläse
US9334875B2 (en) * 2010-10-25 2016-05-10 Mitsubishi Heavy Industries, Ltd. Multiblade centrifugal fan and air conditioner equipped with the same
US20160273780A1 (en) * 2013-10-18 2016-09-22 Whirlpool Corporation Household cooking appliance
DE102015213470A1 (de) * 2015-07-17 2017-01-19 Wilhelm Bruckbauer Lüfterbaustein
EP3620721A1 (de) 2018-09-10 2020-03-11 Berbel Ablufttechnik Gmbh Vorrichtung zur muldenabsaugung von auf einem kochfeld erzeugter abluft

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9334875B2 (en) * 2010-10-25 2016-05-10 Mitsubishi Heavy Industries, Ltd. Multiblade centrifugal fan and air conditioner equipped with the same
EP2738394A1 (de) * 2012-11-29 2014-06-04 BSH Bosch und Siemens Hausgeräte GmbH Gehäuse für ein Radialgebläse und Radialgebläse
US20160273780A1 (en) * 2013-10-18 2016-09-22 Whirlpool Corporation Household cooking appliance
DE102015213470A1 (de) * 2015-07-17 2017-01-19 Wilhelm Bruckbauer Lüfterbaustein
EP3620721A1 (de) 2018-09-10 2020-03-11 Berbel Ablufttechnik Gmbh Vorrichtung zur muldenabsaugung von auf einem kochfeld erzeugter abluft

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