Classifications

• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47L—DOMESTIC WASHING OR CLEANING; SUCTION CLEANERS IN GENERAL
  • A47L5/00—Structural features of suction cleaners
  • A47L5/12—Structural features of suction cleaners with power-driven air-pumps or air-compressors, e.g. driven by motor vehicle engine vacuum
  • A47L5/22—Structural features of suction cleaners with power-driven air-pumps or air-compressors, e.g. driven by motor vehicle engine vacuum with rotary fans
• • 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
  • F04D29/44—Fluid-guiding means, e.g. diffusers
  • F04D29/441—Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
  • F04D29/444—Bladed diffusers
• • 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

• Diffusers are used here, which are provided with evenly distributed air ducts around the periphery of the impeller.
• the task of these diffusers is to bend the air flowing out of the impeller at a flat flow angle and to ensure a shorter flow through the diffuser area than in an unspanned annular space. This leads to an increase in the efficiency of the entire fan.
• the gap between the impeller and the diffuser inlet must be as small as possible. The small gap, however, results in higher noise components (rotary sound) and a greater sensitivity of the fan (noise development, so-called "pumping") when the volume flow deviates from the optimum point.
• An arrangement is known from EP-A2 0 602 007 in which the ratio of the channel height of the diffuser to the fan wheel outlet height corresponds to the ratio mentioned above.
• the diffuser has curved flow channels, the channel walls being evenly slightly curved.
• the wall thickness of the diffuser channel walls is chosen to be constant.
• DE-A1-41 30 901 in which a diffuser is used with flow channels running in a more curved manner.
• the design can be chosen so that an area of the diffuser channel sole is formed which is aligned parallel to the impeller bottom wall, with a ratio of the diffuser wall height in this area to the guide vane height of 1.7 to 1.2 and the area running parallel to this a step-like lowered area of the diffuser channel bottom adjoins radially outward, thus increasing the specified height ratio in this area.
• the diffuser channel base is designed to slope radially outwards, preferably at an angle of approximately 12 ° to 20 °. To further improve efficiency and Increasing the stability with severe throttling, it is also advantageous that a distance between the diffuser walls in the circumferential direction increases radially outwards.
• the diffuser duct ceiling is arranged perpendicular to the fan axis, this results in a diffuser duct greatly expanded in the axial direction with a corresponding expansion of 12 ° to 20 °.
• the entire channel expansion is increased by the level channel expansion between the adjacent diffuser walls from 2 ° to 10 °. Due to the flow separation, channel enlargements of this size have so far been considered detrimental to aerodynamic stability and efficiency. Since cyclical flow separations mark the beginning of the "pump" area, poor efficiency and early "pumping" would be expected with such a greatly expanded diffuser channel.
• the area of curvature extends beyond the tangent in the direction of rotation of the impeller.
• An arrangement in which the region of curvature intersects the tangent is preferred. Accordingly, at least in the region of curvature, the flow deflection running along or parallel to the tangent is exited.
• an initial length of the straight section coincide with the tangent or extend parallel to it.
• the part length that continues straight along this initial length is preferably angled to this initial length, an angle of 1 ° to 3 °, preferably 2 °, being chosen here. It is proposed that the initial length be approximately one tenth to one fifth of the total length of the section currently running.
• a second angled part length adjoins the initial length, for which purpose it is proposed according to the invention that a second part length adjoins the first part length, which is possibly set back by an angling against the direction of rotation of the impeller.
• a diffuser wall in which an initial length extends parallel to the tangent, a second subsequent straight partial length angled to the initial length in the direction of rotation of the impeller extends in front of the tangent, and a final one Outer area of curvature, starting from the second partial length, extends into an area behind the tangent - viewed in the direction of rotation of the impeller - and thereby intersects the tangent.
• the diffuser blade end point is thus extended beyond the tangent in the direction of rotation of the fan.
• the distance between the individual diffuser walls is selected so that a dimension between a diffuser wall inlet tip and the adjacent diffuser wall of the diffuser inner radius multiplied by a factor of 0.061 to 0.049 is obtained.
• a distance between the second, straight partial section, which is oriented at an angle to the initial length, and an adjacent diffuser wall is selected, which is greater by a factor of 1.02 to 1.25 than the distance between the diffuser wall inlet tip and the adjacent diffuser wall ,
• Such a blade contour is easy to produce by injection molding, very dimensionally stable and shows significantly less tendency to warp than curved blades.
• the blade tip or diffuser wall tip is preferably beveled at an angle of 10 ° to 15 °, so that no cross-sectional constriction occurs in the diffuser channel at this point.
• the blade tip can be rounded with a radius of up to a quarter of the wall thickness of the diffuser wall for production-oriented design.
• the already mentioned blower pot has to be provided with an inner diameter which is 1.035 to 1.075 times larger than the outer diameter of the diffuser.
• the tangential entry area of the diffuser wall - the initial length of the straight section - has the task of making the air flow emerging from the blower tangential regardless of the momentary inflow angle Redirect direction.
• the flow region deflected in this way entrains the rest of the unaffected flow.
• the distance between the diffuser wall inlet tip and the adjacent diffuser wall is dimensioned such that the entire diffuser channel is flowed against almost tangentially.
• a detachment is provoked by the angulation of the second partial area of the section that is currently running, but this is stabilized by the impact vortex already mentioned, with which there is a direct connection.
• the detachment area cannot go out of the diffuser channel, since the blade end extends beyond the tangent. The detachment area is thus spatially limited and stabilized by the impact vortex.
• the detachment area is displaced in the direction of the impact vortex and the entire enlarged channel width between the angled area and the adjacent diffuser wall is used.
• the speed profile of the air flow emerging from the fan wheel is uneven across the fan wheel division. This constantly changes the flow angle at the diffuser inlet.
• a conventional diffuser blade design conditions change rapidly, which result in an adjacent or detaching flow along the diffuser walls and rotating sound noises.
• a largely tangential diffuser channel flow is achieved and the separation area reacts to the different inflow conditions at low volume flows by growing or shrinking.
• the rotating sound and the rotating sound overtone are greatly reduced.
• a ratio of the fan pitch to the diffuser pitch of 2.5 to 3.0 a ratio of 2.74 is preferably selected.
• a recess is provided in the diffuser channel sole outside of a diffuser wall covering up to the outer diameter of the return vanes arranged on the underside.
• a ratio of the outer diameter of the return vane to the outer diameter of the diffuser wall is chosen to be from 0.925 to 0.98.
• the height of the return vanes is preferably approximately 1.2 to 1.6 times the diffuser wall height. Due to this configuration, the above-mentioned recess outside the diffuser wall covering neither reduces the efficiency, nor does it increase the risk of “pumping”.
• An electric motor 1 with an impeller 3 arranged on a rotor shaft 2 and a diffuser 4 radially adjoining the impeller 3 is shown and described first with reference to FIG added.
• the diffuser 4, however, is not rotatably attached to a bearing receiving element 5.
• the electric motor 1 is surrounded by a motor housing 6, which is also attached to the bearing receiving element 5.
• the diffuser 4 has an outer diameter D2, which in the exemplary embodiment shown is approximately 108 mm.
• the aforementioned diffuser walls 8 are arranged in an annular outer region of the diffuser carrier 9, the diffuser walls 8 starting at the diffuser outer diameter D2 and extending to a diffuser inner diameter D1, which diffuser inner diameter D1 in the exemplary embodiment shown is approximately Is 94 mm.
• the impeller 3 is mounted in the free space of the diffuser 4 formed by the inner diameter D1 (cf. FIG. 1).
• the diffuser 4 has a circular opening 11 in the center for the passage of an equally circular central region of the bearing receiving element 5. Furthermore, the diffuser 4 has two bores 12 arranged symmetrically to one another in the region of its support 9 for fastening the Diffuser 4 on the bearing receiving element 5 by means of screws, rivets or the like.
• Diffuser channels 13 are formed between the diffuser walls 8, with a diffuser channel height greatly expanding in the radial direction.
• This diffuser channel sole 14 initially extends in a radial inner region parallel to the overall extent of the carrier 9, i. H. perpendicular to the body axis of the diffuser and thus also perpendicular to the axis of rotation of the impeller 3. This is followed by a lowering of the channel base 14, the latter being designed to slope radially outwards. This results in an expansion angle alpha of approximately 12 ° to 20 °.
• the return blades 10 arranged on the underside of the carrier 9 have a height b1 which corresponds to 1.2 to 1.6 times the diffuser wall height b2.
• a diffuser wall height b2 of 10.5 mm and a return blade height b1 of 12 mm are selected, with a total height b3 of the diffuser 4 of approximately 27 mm.
• a total of twenty diffuser walls 8 are provided on the upper side of the carrier 9 to form diffuser channels 13.
• Each diffuser wall 8 has a largely constant wall thickness w of approximately 1.2 mm.
• the diffuser wall 8 extends in the radial direction along a tangent T on a circle defined by the inner diameter of the diffuser D1 (cf. FIG. 9).
• the diffuser wall 8 is composed of a section G1 which initially runs essentially straight in the radial direction and an adjoining outer curvature region K, the straight section G1 being approximately 55 to 75% of the total length 1 of the diffuser wall 8, the total length 1 being parallel is tapped to the tangent T.
• the total length 1 is approximately 25 mm.
• the straight section G1 has a length of approximately 18 mm.
• the curved area K and its diffuser wall end point E open onto the diffuser outer diameter D2.
• This diffuser wall contour is easy to produce by injection molding, very dimensionally stable and shows significantly less tendency to warp than curved walls.
• the diffuser wall tip SP is chamfered at an angle gamma of approx. 10 to 15 °. This configuration ensures that no cross-sectional constriction occurs at this point in the diffuser channel 13.
• the diffuser wall tip SP can be rounded off with a radius r, this radius r being dimensioned with a maximum of a quarter of the wall thickness w.
• the return vanes 10 arranged on the underside of the diffuser carrier 9 are also integrally formed on the same in a radial outer region, these being between a blade outer diameter D3 and a blade inner diameter D4 extend to form the feedback wheel 16.
• the outer diameter D3 lies with its value between the outer and inner diameters D2 and D1 of the diffuser walls 8.
• the blade outer diameter D3 is approximately 103 mm.
• the inside diameter D4 of the feedback wheel 16 is approx. 73 mm.
• the dimensional ratios of the impeller 3 and the diffuser 4 are selected such that the inside diameter D1 of the diffuser 4 corresponds approximately to 1.01 to 1.1 times the outside diameter D5 of the impeller 3. Furthermore, the height ratio of the diffuser wall height b2 to the fan wheel height b4, measured at a radially outer end, is selected such that the diffuser wall height b2 corresponds to approximately 1.7 to 1.2 times the fan wheel height b4. This value is significantly higher than the values stated in the prior art.
• the diffuser channel sole is designed with a slope.
• the blower pot cover 17 forming the diffuser duct ceiling is perpendicular to the blower axis, which results in a diffuser duct 13 which is greatly expanded in the axial direction.
• the entire channel expansion is increased by the flat channel expansion between the adjacent diffuser walls 8 of approximately 2 ° to 10 °.
• a flow separation hereinafter referred to as impact vortex Z1
• impact vortex Z1 is used to improve the stability of the flow and to prevent "pumping" from occurring even down to a flow rate of zero.
• the fan wheel 3 is arranged to support the impact vortex Z1 in such a way that the fan wheel cover wall 18 is flush with the plane of the duct ceiling or the blower pot cover 17 to 1 to 2 mm and thus an optimal flow from the impeller outlet along the duct ceiling or blower pot cover 17 is formed.
• the impact vortex Z1 forms a fluid wall I, which is set as a function of the flow. In addition to ensuring an optimized main flow, a low-loss deflection of the main flow to the feedback wheel 16 is achieved.
• the blower pot 7 is dimensioned such that the inner diameter of the blower pot D7 corresponds approximately to 1.035 to 1.075 times the outer diameter of the diffuser D2.
• an angulation Z2 is provoked by the angulation of the area G2, but this is stabilized by the impact vortex Z1, with which there is a direct connection.
• the detachment area cannot go out of the diffuser channel 13 because the diffuser wall end E is drawn beyond the tangent T.
• the detachment area Z2 is thus spatially limited and stabilized by the impact vortex Z1.
• the detachment area Z2 is displaced in the direction of the impact vortex Z1 and the entire channel width a2 is used.
• the speed profile of the air flow emerging from the impeller 3 is uneven over the impeller division. This constantly changes the flow angle at the diffuser inlet.
• a largely tangential diffuser channel flow is achieved and the separation area Z2 reacts to the different inflow conditions at low volume flows by growing or shrinking.
• the rotating sound and the rotating sound overtone are greatly reduced.
• a slot V can be provided on a diffuser wall or on two symmetrically opposite diffuser walls 8 without impairing the noise and efficiency behavior (cf. FIG. 10).
• This slot V lies outside the diffuser wall cover Y and makes it possible to carry out a complete balancing on the impeller 3.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Motor Or Generator Cooling System (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Harvester Elements (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
• Automatic Cycles, And Cycles In General (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=26022947

Family Applications (1)

Country Status (11)

Families Citing this family (22)

Family Cites Families (3)

• 1996
  • 1996-02-16 DE DE19605742A patent/DE19605742A1/de not_active Withdrawn
• 1997
  • 1997-03-06 WO PCT/EP1997/001139 patent/WO1998038899A1/de not_active Ceased
  • 1997-03-06 DK DK97914196T patent/DK0964635T3/da active
  • 1997-03-06 JP JP53808398A patent/JP2001513861A/ja active Pending
  • 1997-03-06 PL PL97335112A patent/PL183560B1/pl not_active IP Right Cessation
  • 1997-03-06 CZ CZ0300499A patent/CZ297722B6/cs not_active IP Right Cessation
  • 1997-03-06 EP EP97914196A patent/EP0964635B1/de not_active Expired - Lifetime
  • 1997-03-06 AT AT97914196T patent/ATE231703T1/de not_active IP Right Cessation
  • 1997-03-06 ES ES97914196T patent/ES2187763T3/es not_active Expired - Lifetime
  • 1997-03-06 PT PT97914196T patent/PT964635E/pt unknown
  • 1997-03-06 DE DE59709247T patent/DE59709247D1/de not_active Expired - Fee Related
• 1999
  • 1999-09-02 SK SK1200-99A patent/SK285632B6/sk unknown

Also Published As

Similar Documents

Legal Events