EP3704385B1 - Fan - Google Patents
Fan Download PDFInfo
- Publication number
- EP3704385B1 EP3704385B1 EP18807706.9A EP18807706A EP3704385B1 EP 3704385 B1 EP3704385 B1 EP 3704385B1 EP 18807706 A EP18807706 A EP 18807706A EP 3704385 B1 EP3704385 B1 EP 3704385B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cover plate
- impeller
- projection
- ventilation fan
- tapering
- 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.)
- Active
Links
- 238000009423 ventilation Methods 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000005034 decoration Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 238000011176 pooling Methods 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Images
Classifications
-
- 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
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/667—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by influencing the flow pattern, e.g. suppression of turbulence
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
-
- 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
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/281—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for fans or blowers
-
- 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
- F04D29/403—Casings; Connections of working fluid especially adapted for elastic fluid pumps
-
- 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
- F04D29/4213—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps suction ports
-
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/081—Air-flow control members, e.g. louvres, grilles, flaps or guide plates for guiding air around a curve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F7/00—Ventilation
- F24F7/007—Ventilation with forced flow
- F24F7/013—Ventilation with forced flow using wall or window fans, displacing air through the wall or window
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/06—Helico-centrifugal pumps
-
- 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
- F05D2250/20—Three-dimensional
- F05D2250/23—Three-dimensional prismatic
- F05D2250/232—Three-dimensional prismatic conical
-
- 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
- F05D2250/51—Inlet
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/20—Casings or covers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/24—Means for preventing or suppressing noise
Definitions
- This invention relates to fans, in particular ventilation fans such as extractor fans of the type suitable for affixing to a wall or a ceiling or in a window.
- Fans of this type may be used to ventilate a room via a wall or ceiling duct. They typically employ a motor driven impeller to draw air through the duct.
- a grill or cover plate is normally disposed in front of the impeller. The grill or cover plate serves to prevent objects such as body parts or items of clothing coming into contact with or potentially being caught in the fast-spinning impeller. Cover plates are often used to improve the visual appeal of the fan by obscuring the view of the internal components of the fan.
- a grill disposed in front of the impeller, provides low impedance to air flowing towards the impeller.
- grills can be unsightly as the front facing gaps still allow the spinning impeller and other internals of the fan to be seen from the front, i.e. from within the room. Grills are also susceptible to dust build up and can be difficult to clean.
- a cover plate may be provided in front of the fan.
- Such solid cover plates hide the impeller and the rest of the internal fan structure completely and allow no frontal access at all to the impeller.
- these types of cover plates must be positioned slightly away from the wall via an opening created around the sides of the cover plate and consequently, while these cover plates are more visually appealing from the front, they protrude from the wall or ceiling more than other designs.
- a cover plate means that the air must travel a more circuitous route to reach the impeller, involving at least one change of direction as it travels behind the cover plate and then through the fan.
- the cover plate may slightly impede the air flow.
- Turbulence can result in inefficiency, requiring more power for a given throughput of air and may also result in increased noise.
- JP 2008 190781 A discloses a ventilating device having a decoration panel for closing a front face of a suction opening of an axial flow-type air blower. An approximately conical guide member is disposed on a back side of the decoration panel.
- JP 2003 120596 A discloses a portable blower comprising a frame having a horizontal part mounted with a blower and a vertical part on one side of which the back of a worker abuts and to the other side of which the air inlet port of the blower is opposed. The other side of the vertical part of the frame is provided with a laminar flow means for suppressing the turbulence of sucked air.
- JP H04 1349 U discloses a ventilation system which is mounted on a ceiling or the like and which exhausts indoor air into an outdoor space through a ventilation duct.
- WO 2013/181904 A1 discloses an oblique flow fan for an air conditioning indoor unit, the oblique flow fan comprising a wheel hub with a conical or spherical air guide surface.
- the invention provides a domestic ventilation fan according to claim 1.
- the fan comprises a cover plate that comprises:
- a cover plate for a fan that improves air flow into the fan, reducing cross-currents, eddies and turbulence and making the flow more laminar. Air flowing from the edge of the cover plate towards the centre is guided substantially perpendicularly away from the cover plate by the projection such that air flowing from opposing edges of the cover plate is largely prevented from colliding and causing turbulence.
- a reduction in turbulent flow improves efficiency and enables a greater air flow rate for a given opening and a given fan speed This improvement in efficiency may be used to allow the cover plate to be positioned closer to a wall, ceiling or mounting plate, i.e. providing a smaller opening around and behind the cover plate.
- the improved efficiency may be used to draw more air through the fan for a given power and/or fan speed.
- Minimising noise is also generally an important consideration in fan design as fans are often used in domestic settings, e.g., a bathroom or a kitchen, where noisy fans can be a nuisance. Turbulence is often a significant contributor to noise and therefore the reduction in turbulent flow provided by the cover plate projection reduces the amount of noise produced by a fan. In addition, the fact that a fan equipped with such a cover plate may be operated at a lower speed while providing the same level of airflow can also help to minimise the production of noise.
- the tapering projection may take any suitable form so as to provide the best guidance of airflows towards the impeller of the fan.
- air flow could be expected to arrive at the fan in an asymmetric manner and the projection may be asymmetrically designed accordingly for best flow management.
- the tapering portion is preferably rotationally symmetric about a central axis. This further reduces turbulence by ensuring that air flowing towards the projection from any one direction is guided smoothly away from the cover plate, with minimal interference from air flowing towards the projection from any other direction.
- the profile of the tapering projection may influence the flow of air and consequently the degree of turbulence experienced.
- the profile of the tapering projection may be designed for a particular application and for the expected airflows in that application.
- a tapering projection with only a shallow gradient i.e. one in which the diameter of the projection decreases quickly as it projects away from the outer surface
- a tapering projection with only a steep gradient may cause air flowing from the sides of the cover plate towards the projection to be reflected back on itself, again causing turbulence.
- the tapering projection has a curved profile that varies in gradient.
- the tapering projection has a shallower gradient in regions where it has its greatest diameter.
- the tapering projection has a steeper gradient in regions where it has its narrowest diameter.
- the tapering projection preferably has a profile with shallow gradient nearer to the outer surface and a steeper gradient further away from the outer surface.
- the projection has a curved profile that smoothly varies from a shallow gradient to a steep gradient as it projects from the outer surface.
- a shallow gradient is no more than 30 degrees, preferably no more than 20 degrees, more preferably no more than 10 degrees, and a steep gradient is preferably at least 60 degrees, more preferably at least 70 degrees, yet more preferably at least 80 degrees.
- a mounting plane being a plane of the surface to which the fan is mounted such as a wall or ceiling. It may be noted that the tapering projection typically extends perpendicular to that plane.
- the front facing most visible surface of a cover plate prefferably comprises at least one substantially planar region, typically arranged to be parallel to the mounting surface such as a wall or ceiling.
- the projection preferably projects along a projection axis which is perpendicular to this planar region.
- the profile of the tapering projection may comprise a section that makes an angle of no more than 60 degrees with the projection axis, preferably no more than 45 degrees, more preferably no more than 30 degrees.
- the projection has a substantially conical shape in that it tapers from a wide base towards a point (although preferably in a curved profile as discussed above).
- the projection preferably tapers to a narrowest point.
- the narrowest point is located at the most distant point of the projection from the outer surface.
- the narrowest point may form a sharp point or a rounded point or it may be the narrowest point of a frustum, i.e. still having a non-insignificant width parallel to the mounting plane (perpendicular to the conic projection's axis).
- the narrowest point may also be a waist such that the projection widens again as it projects further from the outer surface of the cover plate, thus directing air radially outwardly at its distal end.
- the size of the projection will have an impact on the effectiveness of the cover plate in redirecting air appropriately.
- a large projection with a large width (perpendicular to the extension direction of the projection) and height (in the extension direction of the projection), enables the air to be redirected more gently (i.e. the effective radius of curvature may be greater) thus reducing turbulence.
- a larger projection may require more material to manufacture, rendering the cover plate heavier, more expensive and more complicated to produce. If the projection were too large, it could also increase the size of the cover plate, which in space limited applications can be important or it could adversely affect the aesthetics if it required a wider cover plate or caused the cover plate to extend further away from the wall/ceiling.
- the projection may have an axial extent (in the direction perpendicular to the wall/ceiling) of at least 1 cm, preferably at least 2 cm, more preferably at least 3 cm.
- the projection preferably has an axial extent of no more than 8 cm, preferably no more than 6 cm, more preferably no more than 5 cm.
- the projection may have a width (in the direction parallel to the wall/ceiling) of at least 3 cm, preferably at least 4 cm, more preferably at least 5 cm.
- the projection preferably has a width of no more than 20 cm, preferably no more than 15 cm, more preferably no more than 10 cm.
- the cover plate comprises at least a main portion and a detachable portion.
- the cover plate comprises at least a main portion and a detachable portion.
- the projection is formed on the main portion.
- the detachable portion forms part of the outer surface, allowing the detachable portion to be attached to the main portion even when the inner surface is not accessible, e.g.
- the projection on the inner surface may then be formed as a thin walled structure such that a cavity is formed behind the projection (i.e. on the outer surface side of the main portion of the cover plate). This cavity can then be closed off by the detachable portion which essentially forms a cap that forms a substantially continuous surface over the cavity to make the cover plate as a whole aesthetically pleasing without excessive weight or cost.
- the inner surface of the cover plate may comprise a section which is substantially parallel to the outer surface of the cover plate.
- the tapering projection curves smoothly to meet this parallel section which is in turn preferably parallel to the mounting plane (wall or ceiling).
- the cover plate may have a radially outer portion that extends in the same direction as the tapering projection, i.e. it extends back towards the wall or ceiling (or other structure) to which the fan is mounted, thus producing an overall dome shape for the cover plate.
- the cover plate does not contain any substantial through holes from the outer surface to the inner surface, such that air is largely prevented from flowing through the cover plate. It is preferable that the ingress of air through the cover plate is reduced so as to minimise turbulence at the rear of the cover plate. A cover plate with no substantial holes may also be easier to clean.
- the cover plate comprises one or more drip holes (or paths) from the inner surface to the outer surface. These holes provide a pathway for water to travel from the inner surface out to the outer surface of the cover plate to avoid pooling and potential damage.
- drip holes may be formed as part of the attachment mechanism for the detachable part discussed above.
- the detachable part may be clipped onto the main part through holes in the main part which can also serve as the drip holes for water.
- the fan comprises:
- the improved appearance, energy consumption and reduced noise production of a fan according to the present invention make it particularly suitable for domestic settings, for example in a bathroom or a kitchen.
- the fan is a domestic ventilation fan such as those used in household kitchens and bathrooms.
- the fan is mountable on a wall or a ceiling or in a window.
- the impeller may comprise a hub with a plurality of blades extending therefrom.
- the impeller comprises an inlet side and an outlet side, and the hub comprises a tapering projection on the inlet side that narrows as it projects away from the hub.
- Having a tapering projection extending away from the hub provides an additional air guiding surface that operates in conjunction with the tapering projection on the cover plate to receive the air directed towards the impeller by the cover plate and continue to guide the air efficiently towards the blades of the impeller.
- the tapering projection on the impeller is preferably centrally located and preferably symmetrical around the rotational axis of the impeller so that the impeller is mass balanced around its rotational axis to avoid unwanted oscillations / vibrations.
- the tapering projection on the impeller preferably has a surface that tapers from a shallow gradient to a steeper gradient as it narrows away from the hub.
- the tapering projection of the impeller and the tapering projection of the cover plate taper away from one another such that in some preferred embodiments their narrowest portions (e.g. tips) face each other.
- the impeller may be designed according to particular requirements of the fan.
- the impeller may be an axial impeller or a centrifugal impeller.
- the impeller is a mixed flow impeller.
- a mixed flow impeller combines the characteristics of an axial flow impeller such as resistance to back flow with the improved rates of air movement of a centrifugal impeller.
- the blades of the mixed flow impeller project axially forwards from the hub (towards the air inlet side) so as to push the air outwards (centrifugally) as well as extending radially outwardly from the hub so as to push the air backwards (axially).
- the tapering projection helps to redirect the air towards the mixed flow blades in a more efficient manner.
- mixed flow impellers typically interact with the incoming air predominantly at the lower part of the blades (nearest the hub) with the upper parts of the blades (furthest from the blades) not contributing as much to the movement of air.
- the tapering projection guides the air towards the blades more uniformly such that the air interacts with the mixed flow blades across the whole length of the blades making better use of the whole blade surface, thus increasing the efficiency of the impeller as a whole and increasing the amount of air that it can move for a given size of impeller and rotational speed.
- the tapering projection of the impeller may have a similar profile to the tapering projection of the cover plate, but this is not necessary and it can be designed to redirect air optimally for any particular design of impeller blades. However, preferably the projection has a significant axial extent so as to provide a long guiding path to the air with a relatively large radius of curvature.
- the tapering projection extends the axial length of the impeller such that in preferred embodiments the axial extent of the impeller is greater than the radius of the hub. In some preferred embodiments (e.g. for impellers for 100 mm or 150 mm ventilation fans) the impeller has an axial extent (including the tapering projection) of at least 1.5 cm, preferably at least 1.75 cm, more preferably at least 2 cm.
- the tapering projection preferably has a curved profile that varies in gradient.
- the tapering projection may have a profile with a shallower gradient at the radially outward part of the hub and a steeper gradient towards the impeller rotational axis.
- An impeller for a fan that comprises:
- an impeller for a fan that improves air flow and reduces turbulence.
- the shape of the impeller's hub pushes air to the edges of the blades, ensuring that an increased surface area of each blade may be utilised to impel air, leading to more efficient operation of the impeller.
- the tapering projection causes air flowing towards the inlet side of the impeller to be guided away from the centre of the impeller. This promotes more laminar airflow and minimises the prevalence of turbulence that might otherwise form near the centre of the impeller. Reduced turbulence leads to improved air flow for a given noise and power usage.
- the tapering projection is rotationally symmetric about the impeller's axis of rotation.
- a rotationally symmetric hub may guide air flow more evenly, and may reduce vibration, which can be produced when an asymmetric hub is rotated. Such vibrations are undesirable, as they produce noise.
- An asymmetric hub may also draw a variable load when driven to rotate at a constant rate, which is undesirable in some drive systems.
- the invention applies to centrifugal, mixed flow and axial type impellers, however preferably the impeller is a mixed flow type.
- Centrifugal impellers have blades with a leading edge extending substantially parallel to the axis of rotation of the impeller whereas axial impellers have blades with the leading edge extending substantially perpendicular to the axis of rotation of the impeller.
- Mixed flow type impellers are a hybrid type with blades angled in between the axial and centrifugal arrangements, i.e. the blades are angled so as to impart some radial and some axial momentum to the air.
- the tapering projection preferably has a surface that tapers from a shallow gradient to a steeper gradient as it narrows away from the hub.
- the axial extent of the impeller is preferably greater than the radius of the hub.
- the impeller may in some embodiments have an axial extent of at least 1.5 cm, preferably at least 1.75 cm, more preferably at least 2 cm.
- an impeller as disclosed herein comprises part of a fan, preferably one that also comprises a cover plate according to the present disclosure.
- the tapering projections of the both the cover plate and the impeller are aligned, and positioned to minimise the distance between the two. This configuration results in a minimal amount of turbulence. While it is desirable to have the two tapering portions as proximal as possible, manufacturing limitations (tolerances) may result in a practical separation being required, but in some examples it is preferred that this separation be no more than 2mm. Keeping the two projections as close as possible minimises cross-flow and turbulence arising at the gap between the two projections.
- FIG. 1 shows a cross section of a circular cover plate for a fan according to one embodiment of the present invention.
- the cover plate 2 comprises a main body 4 and a detachable face plate 6.
- the face plate 6 comprises a cylinder which is detachably connected to the main body 4 by means of clips 16.
- the face plate 6, main body 4 and cover plate 2 as a whole are substantially rotationally symmetric around a central axis C.
- the main body 4 comprises a radially outer portion 8 with a hollow frustroconical shape and a radially inner portion 10.
- the radially inner portion 10 comprises a projection 12 that projects and narrows along the central axis C on a rear side of the cover plate 2 to a central point 14.
- the projection 12 is substantially conical in shape.
- the profile of the projection 12 comprises a gradient that varies smoothly from a shallower gradient at its base to a steeper gradient as it nears the central point 14.
- the inner portion 10 also comprises the clips 16, which detachably connect the face plate 6 to the main body 4 on a front side of the cover plate 2, opposite to the rear side.
- the clips 16 detachably connect the face plate 6 to the main body 4 on a front side of the cover plate 2, opposite to the rear side.
- a contiguous front surface 18 is formed, comprised of front facing surfaces of the outer portion 8 and the face plate 6.
- the cover plate also comprises a contiguous inner surface 19, comprised of rearward facing surfaces of the main body 4 and the inner portion 10, that curves smoothly from a radially outermost edge to the central point 14.
- a fan 20 comprises the cover plate 2 of Figure 1 , a mounting plate 22 and an impeller 24, all of which are substantially rotationally symmetric and lie with their axis of rotational symmetry on a central axis C.
- the mounting plate 22 comprises a central cavity in which the impeller 24 is disposed, and the cover plate 2 is disposed in front of both of the mounting plate 22 and the impeller 24, such that the inner surface 19 of the cover plate 2 faces both the mounting plate and the impeller 24.
- the tapering projection 12 of the cover plate 2 projects away from the inner surface 19 towards the impeller 24.
- the cover plate 2 is rigidly connected to the mounting plate 22.
- the cover plate 2 is spaced away from the mounting plate 22 such that an inlet gap 26 is formed at the edge of the fan 20, between a radially outermost edge of the cover plate 2 and the outer edge of the mounting plate 22.
- the mounting plate 22 (and hence the rest of the fan 20) is attached to a fixed surface 28 (e.g. a wall) which comprises a cylindrical duct 30 (e.g. a ventilation duct).
- the cylindrical duct 30 lies with its axis of rotational symmetry on the central axis C, such that it is aligned with the central cavity of the mounting plate 22.
- the front surface 18 of the cover plate 2 faces away from the fixed surface 28 and defines the front of the fan 20.
- the cover plate 2 has a larger diameter than the mounting plate 22 and impeller 24 such that, when the fan 20 is mounted as described, the mounting plate 22 and impeller 24 are not visible from the front.
- the impeller 24 comprises a plurality of blades 32, and in use, the impeller 24 is driven to rotate about the central axis by a driving means (e.g. a motor, not shown). As the impeller 24 rotates, the resultant motion of the blades 32 causes air surrounding the fan 20 to be drawn through the inlet gap 26, through the impeller 24 and into the duct 30, illustrated here by air flow paths 34.
- a driving means e.g. a motor, not shown
- the profile of the projection 12 smoothly guides the air flowing in from the inlet gap 26 perpendicularly away from the cover plate 2 towards the impeller 24, reducing turbulence caused by air flowing from opposite edges of the fan 20 meeting at the centre.
- the reduction in turbulence due to the shape of the cover plate 2 means that the same volume of air flow can be provided while producing less noise, using less energy and with a smaller inlet gap 26 than would be required with a conventional cover plate.
- Turbulence may be further reduced, and efficiency further increased by providing a specially shaped impeller with a tapering projection similar to that of the cover plate, as illustrated in Figure 3 .
- FIG 3 shows an impeller 100 that comprises a hub 102 and a plurality of blades 104.
- the impeller 100 is a mixed flow type impeller wherein the blades 104 extend radially and forwards from the hub 102.
- the impeller 100 is substantially rotationally symmetric about a central axis C and comprises a central drive connector 105, disposed on the central axis C, to which a drive means (not shown) may be connected to rotate the impeller 100 about the central axis C.
- the impeller 100 comprises an inlet side and an outlet side
- the hub 102 comprises a tapering projection 106, rotationally symmetric about the central axis C, on the inlet side that narrows as it projects forwards away from the hub 102 to a central point 108 that lies on the central axis C.
- the tapering projection 106 has a curved profile that varies smoothly from a shallower gradient nearest to the outlet side to a steeper gradient as it nears the central point 108.
- FIG 4 shows a fan 120 that comprises the cover plate 2 of Figure 1 , a mounting plate 22 and the impeller 100 of Figure 3 , all of which are substantially rotationally symmetric and lie with their axis of rotational symmetry on a central axis C.
- the mounting plate 22 comprises a central cavity in which the impeller 100 is disposed, and the cover plate 2 is disposed in front of both of the mounting plate 22 and the impeller 100, such that the inner surface 19 of the cover plate 2 faces both the mounting plate 22 and the impeller 100.
- the cover plate 2 is spaced away from the mounting plate 22 such that an inlet gap 26 is formed at the edge of the fan 120, between a radially outermost edge of the cover plate 2 and the outer edge of the mounting plate 22.
- the fan is mounted to a fixed surface 28 (e.g. a wall) such that the mounting plate 22 and impeller 100 are not visible from the front.
- the impeller 100 is driven to rotate about the central axis C by a driving means (e.g. a motor, not shown) connected to the driving connector 105.
- a driving means e.g. a motor, not shown
- the resultant motion of the blades 104 impels air surrounding the fan 120 through the inlet gap 26, through the impeller 100 from the inlet side to the outlet side and into the duct 30, illustrated here by air flow paths 134 (illustrated here on only one side of the fan, for clarity).
- the profile of the projection 12 of the cover plate 2 smoothly guides air flowing in from the inlet gap 26 perpendicularly away from the cover plate 2 towards the impeller 24, and the tapering projection 106 of the impeller 100 then smoothly guides air towards the outside of the impeller 100.
- the central point 14 of the cover plate 2 and the central point 108 of the impeller 100 are proximal, such that they are separated by only a small gap. This reduces the chances of cross-flow and turbulence arising at the gap.
Description
- This invention relates to fans, in particular ventilation fans such as extractor fans of the type suitable for affixing to a wall or a ceiling or in a window.
- Fans of this type may be used to ventilate a room via a wall or ceiling duct. They typically employ a motor driven impeller to draw air through the duct. A grill or cover plate is normally disposed in front of the impeller. The grill or cover plate serves to prevent objects such as body parts or items of clothing coming into contact with or potentially being caught in the fast-spinning impeller. Cover plates are often used to improve the visual appeal of the fan by obscuring the view of the internal components of the fan.
- A grill, disposed in front of the impeller, provides low impedance to air flowing towards the impeller. However grills can be unsightly as the front facing gaps still allow the spinning impeller and other internals of the fan to be seen from the front, i.e. from within the room. Grills are also susceptible to dust build up and can be difficult to clean.
- As an alternative to a grill, a cover plate may be provided in front of the fan. Such solid cover plates hide the impeller and the rest of the internal fan structure completely and allow no frontal access at all to the impeller. To allow for air flow into the fan, these types of cover plates must be positioned slightly away from the wall via an opening created around the sides of the cover plate and consequently, while these cover plates are more visually appealing from the front, they protrude from the wall or ceiling more than other designs.
- In addition, compared with a grill, a cover plate means that the air must travel a more circuitous route to reach the impeller, involving at least one change of direction as it travels behind the cover plate and then through the fan. Thus, the cover plate may slightly impede the air flow. Additionally, as air is drawn in around the cover plate from all directions, the air from different directions may collide and interfere, causing turbulence. Turbulence can result in inefficiency, requiring more power for a given throughput of air and may also result in increased noise.
-
JP 2008 190781 A JP 2003 120596 A JP H04 1349 U WO 2013/181904 A1 discloses an oblique flow fan for an air conditioning indoor unit, the oblique flow fan comprising a wheel hub with a conical or spherical air guide surface. - From a first aspect, the invention provides a domestic ventilation fan according to
claim 1. - The fan comprises a cover plate that comprises:
- an outer surface; and
- an inner surface;
- Thus a cover plate for a fan is provided that improves air flow into the fan, reducing cross-currents, eddies and turbulence and making the flow more laminar. Air flowing from the edge of the cover plate towards the centre is guided substantially perpendicularly away from the cover plate by the projection such that air flowing from opposing edges of the cover plate is largely prevented from colliding and causing turbulence. A reduction in turbulent flow improves efficiency and enables a greater air flow rate for a given opening and a given fan speed This improvement in efficiency may be used to allow the cover plate to be positioned closer to a wall, ceiling or mounting plate, i.e. providing a smaller opening around and behind the cover plate.
- Alternatively, the improved efficiency may be used to draw more air through the fan for a given power and/or fan speed.
- Minimising noise is also generally an important consideration in fan design as fans are often used in domestic settings, e.g., a bathroom or a kitchen, where noisy fans can be a nuisance. Turbulence is often a significant contributor to noise and therefore the reduction in turbulent flow provided by the cover plate projection reduces the amount of noise produced by a fan. In addition, the fact that a fan equipped with such a cover plate may be operated at a lower speed while providing the same level of airflow can also help to minimise the production of noise.
- The tapering projection may take any suitable form so as to provide the best guidance of airflows towards the impeller of the fan. In some cases, air flow could be expected to arrive at the fan in an asymmetric manner and the projection may be asymmetrically designed accordingly for best flow management. However in the majority of circumstances where the flow into the fan is expected to be substantially symmetrical, the tapering portion is preferably rotationally symmetric about a central axis. This further reduces turbulence by ensuring that air flowing towards the projection from any one direction is guided smoothly away from the cover plate, with minimal interference from air flowing towards the projection from any other direction.
- The profile of the tapering projection may influence the flow of air and consequently the degree of turbulence experienced. The profile of the tapering projection may be designed for a particular application and for the expected airflows in that application. However, in general, a tapering projection with only a shallow gradient (i.e. one in which the diameter of the projection decreases quickly as it projects away from the outer surface) may result in air flowing from opposing sides of the cover plate towards the projection not being redirected effectively such that it still collides at least to some extent, causing turbulence. Alternatively, a tapering projection with only a steep gradient (i.e. one in which the diameter of the projection decreases slowly as it projects away from the outer surface) may cause air flowing from the sides of the cover plate towards the projection to be reflected back on itself, again causing turbulence.
- These problems can be mitigated by providing a tapering projection that comprises portions of both shallow gradient and steep gradient. Preferably the tapering projection has a curved profile that varies in gradient. As the airflow typically enters behind the cover plate substantially parallel to the wall or ceiling and enters the fan substantially perpendicular to that direction, in some embodiments the tapering projection has a shallower gradient in regions where it has its greatest diameter. Preferably the tapering projection has a steeper gradient in regions where it has its narrowest diameter. In other words, the tapering projection preferably has a profile with shallow gradient nearer to the outer surface and a steeper gradient further away from the outer surface. In preferred embodiments the projection has a curved profile that smoothly varies from a shallow gradient to a steep gradient as it projects from the outer surface. Preferably a shallow gradient is no more than 30 degrees, preferably no more than 20 degrees, more preferably no more than 10 degrees, and a steep gradient is preferably at least 60 degrees, more preferably at least 70 degrees, yet more preferably at least 80 degrees. These angles may be defined relative to a mounting plane being a plane of the surface to which the fan is mounted such as a wall or ceiling. It may be noted that the tapering projection typically extends perpendicular to that plane.
- It is often desirable for reasons of aesthetics for the front facing most visible surface of a cover plate to comprise at least one substantially planar region, typically arranged to be parallel to the mounting surface such as a wall or ceiling. The projection preferably projects along a projection axis which is perpendicular to this planar region.
- The profile of the tapering projection may comprise a section that makes an angle of no more than 60 degrees with the projection axis, preferably no more than 45 degrees, more preferably no more than 30 degrees.
- The projection has a substantially conical shape in that it tapers from a wide base towards a point (although preferably in a curved profile as discussed above). The projection preferably tapers to a narrowest point. Preferably the narrowest point is located at the most distant point of the projection from the outer surface. The narrowest point may form a sharp point or a rounded point or it may be the narrowest point of a frustum, i.e. still having a non-insignificant width parallel to the mounting plane (perpendicular to the conic projection's axis). However, the narrowest point may also be a waist such that the projection widens again as it projects further from the outer surface of the cover plate, thus directing air radially outwardly at its distal end.
- The size of the projection will have an impact on the effectiveness of the cover plate in redirecting air appropriately. A large projection, with a large width (perpendicular to the extension direction of the projection) and height (in the extension direction of the projection), enables the air to be redirected more gently (i.e. the effective radius of curvature may be greater) thus reducing turbulence. However a larger projection may require more material to manufacture, rendering the cover plate heavier, more expensive and more complicated to produce. If the projection were too large, it could also increase the size of the cover plate, which in space limited applications can be important or it could adversely affect the aesthetics if it required a wider cover plate or caused the cover plate to extend further away from the wall/ceiling. Contrastingly, a small projection, while cheaper to produce, lighter and more compact, may, if too small, be ineffective at guiding the airflow while preventing turbulent flow. Accordingly, in some arrangements such as in cover plates for fans suitable for mounting in 100 mm or 150 mm ducts, the projection may have an axial extent (in the direction perpendicular to the wall/ceiling) of at least 1 cm, preferably at least 2 cm, more preferably at least 3 cm. The projection preferably has an axial extent of no more than 8 cm, preferably no more than 6 cm, more preferably no more than 5 cm. The projection may have a width (in the direction parallel to the wall/ceiling) of at least 3 cm, preferably at least 4 cm, more preferably at least 5 cm. The projection preferably has a width of no more than 20 cm, preferably no more than 15 cm, more preferably no more than 10 cm.
- Producing a cover plate that comprises a tapering projection can be challenging using conventional techniques. For example, it is undesirable to form the projection as a solid structure as this would require a significant material cost and added weight. Equally, it is difficult to produce components with large enclosed voids. Therefore, in some preferred embodiments the cover plate comprises at least a main portion and a detachable portion. This allows the cover plate to be produced as two components, which are then assembled to produce the final cover plate, allowing production to use conventional machines and techniques. Preferably the projection is formed on the main portion. Preferably the detachable portion forms part of the outer surface, allowing the detachable portion to be attached to the main portion even when the inner surface is not accessible, e.g. when the cover plate is mounted on a fan or against a wall. The projection on the inner surface may then be formed as a thin walled structure such that a cavity is formed behind the projection (i.e. on the outer surface side of the main portion of the cover plate). This cavity can then be closed off by the detachable portion which essentially forms a cap that forms a substantially continuous surface over the cavity to make the cover plate as a whole aesthetically pleasing without excessive weight or cost.
- In some embodiments the inner surface of the cover plate may comprise a section which is substantially parallel to the outer surface of the cover plate. Preferably the tapering projection curves smoothly to meet this parallel section which is in turn preferably parallel to the mounting plane (wall or ceiling). In some embodiments the cover plate may have a radially outer portion that extends in the same direction as the tapering projection, i.e. it extends back towards the wall or ceiling (or other structure) to which the fan is mounted, thus producing an overall dome shape for the cover plate.
- In some sets of embodiments, the cover plate does not contain any substantial through holes from the outer surface to the inner surface, such that air is largely prevented from flowing through the cover plate. It is preferable that the ingress of air through the cover plate is reduced so as to minimise turbulence at the rear of the cover plate. A cover plate with no substantial holes may also be easier to clean.
- Fans are often installed vertically within ceilings with the cover plate facing down into the room. In wet or humid environments such as bathrooms and kitchens, the fan can be susceptible to water (e.g. from splashing or from condensation) dripping or collecting on the inner surface of the cover plate. Accordingly, in some embodiments the cover plate comprises one or more drip holes (or paths) from the inner surface to the outer surface. These holes provide a pathway for water to travel from the inner surface out to the outer surface of the cover plate to avoid pooling and potential damage. Advantageously, such drip holes may be formed as part of the attachment mechanism for the detachable part discussed above. The detachable part may be clipped onto the main part through holes in the main part which can also serve as the drip holes for water.
- The fan comprises:
- a cover plate according to the disclosure herein; and
- an impeller comprising an axis of rotation;
- The improved appearance, energy consumption and reduced noise production of a fan according to the present invention make it particularly suitable for domestic settings, for example in a bathroom or a kitchen. The fan is a domestic ventilation fan such as those used in household kitchens and bathrooms. Preferably the fan is mountable on a wall or a ceiling or in a window.
- It has been further realised that air flow can be further improved by adjusting the shape of the impeller.
- The impeller may comprise a hub with a plurality of blades extending therefrom. The impeller comprises an inlet side and an outlet side, and the hub comprises a tapering projection on the inlet side that narrows as it projects away from the hub.
- Having a tapering projection extending away from the hub provides an additional air guiding surface that operates in conjunction with the tapering projection on the cover plate to receive the air directed towards the impeller by the cover plate and continue to guide the air efficiently towards the blades of the impeller. By guiding the air directly and smoothly to the impeller blades there is a reduction in turbulence and a corresponding reduction in noise as well as an improvement in power efficiency. The tapering projection on the impeller is preferably centrally located and preferably symmetrical around the rotational axis of the impeller so that the impeller is mass balanced around its rotational axis to avoid unwanted oscillations / vibrations. As with the tapering projection on the cover plate, the tapering projection on the impeller preferably has a surface that tapers from a shallow gradient to a steeper gradient as it narrows away from the hub. The tapering projection of the impeller and the tapering projection of the cover plate taper away from one another such that in some preferred embodiments their narrowest portions (e.g. tips) face each other.
- The impeller may be designed according to particular requirements of the fan. The impeller may be an axial impeller or a centrifugal impeller. However, in preferred embodiments the impeller is a mixed flow impeller. A mixed flow impeller combines the characteristics of an axial flow impeller such as resistance to back flow with the improved rates of air movement of a centrifugal impeller. The blades of the mixed flow impeller project axially forwards from the hub (towards the air inlet side) so as to push the air outwards (centrifugally) as well as extending radially outwardly from the hub so as to push the air backwards (axially). The tapering projection helps to redirect the air towards the mixed flow blades in a more efficient manner. It has been found that without the tapering projection, mixed flow impellers typically interact with the incoming air predominantly at the lower part of the blades (nearest the hub) with the upper parts of the blades (furthest from the blades) not contributing as much to the movement of air. The tapering projection guides the air towards the blades more uniformly such that the air interacts with the mixed flow blades across the whole length of the blades making better use of the whole blade surface, thus increasing the efficiency of the impeller as a whole and increasing the amount of air that it can move for a given size of impeller and rotational speed.
- The tapering projection of the impeller may have a similar profile to the tapering projection of the cover plate, but this is not necessary and it can be designed to redirect air optimally for any particular design of impeller blades. However, preferably the projection has a significant axial extent so as to provide a long guiding path to the air with a relatively large radius of curvature. The tapering projection extends the axial length of the impeller such that in preferred embodiments the axial extent of the impeller is greater than the radius of the hub. In some preferred embodiments (e.g. for impellers for 100 mm or 150 mm ventilation fans) the impeller has an axial extent (including the tapering projection) of at least 1.5 cm, preferably at least 1.75 cm, more preferably at least 2 cm.
- Additionally, the tapering projection preferably has a curved profile that varies in gradient. The tapering projection may have a profile with a shallower gradient at the radially outward part of the hub and a steeper gradient towards the impeller rotational axis.
- An impeller for a fan is disclosed that comprises:
- a hub; and
- one or more blades; wherein
- the one or more blades project from the hub; and
- wherein the impeller comprises an inlet side and an outlet side, and the hub comprises a tapering projection on the inlet side that narrows as it projects away from the hub.
- Thus it will be seen by those skilled in the art that an impeller for a fan is disclosed that improves air flow and reduces turbulence. In addition, the shape of the impeller's hub pushes air to the edges of the blades, ensuring that an increased surface area of each blade may be utilised to impel air, leading to more efficient operation of the impeller.
- The tapering projection causes air flowing towards the inlet side of the impeller to be guided away from the centre of the impeller. This promotes more laminar airflow and minimises the prevalence of turbulence that might otherwise form near the centre of the impeller. Reduced turbulence leads to improved air flow for a given noise and power usage.
- Preferably the tapering projection is rotationally symmetric about the impeller's axis of rotation. A rotationally symmetric hub may guide air flow more evenly, and may reduce vibration, which can be produced when an asymmetric hub is rotated. Such vibrations are undesirable, as they produce noise. An asymmetric hub may also draw a variable load when driven to rotate at a constant rate, which is undesirable in some drive systems.
- The invention applies to centrifugal, mixed flow and axial type impellers, however preferably the impeller is a mixed flow type. Centrifugal impellers have blades with a leading edge extending substantially parallel to the axis of rotation of the impeller whereas axial impellers have blades with the leading edge extending substantially perpendicular to the axis of rotation of the impeller. Mixed flow type impellers are a hybrid type with blades angled in between the axial and centrifugal arrangements, i.e. the blades are angled so as to impart some radial and some axial momentum to the air.
- The tapering projection preferably has a surface that tapers from a shallow gradient to a steeper gradient as it narrows away from the hub. The axial extent of the impeller is preferably greater than the radius of the hub. The impeller may in some embodiments have an axial extent of at least 1.5 cm, preferably at least 1.75 cm, more preferably at least 2 cm.
- In some examples an impeller as disclosed herein comprises part of a fan, preferably one that also comprises a cover plate according to the present disclosure. In these examples the tapering projections of the both the cover plate and the impeller are aligned, and positioned to minimise the distance between the two. This configuration results in a minimal amount of turbulence. While it is desirable to have the two tapering portions as proximal as possible, manufacturing limitations (tolerances) may result in a practical separation being required, but in some examples it is preferred that this separation be no more than 2mm. Keeping the two projections as close as possible minimises cross-flow and turbulence arising at the gap between the two projections.
- Features of any aspect or embodiment described herein may, wherever appropriate, be applied to any other aspect or embodiment described herein. Where reference is made to different embodiments or sets of embodiments, it should be understood that these are not necessarily distinct but may overlap.
- Certain preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
-
Figure 1 is a cross sectional schematic view of a cover plate according to an embodiment of the invention; -
Figure 2 is a cross sectional schematic view of a fan not forming part of the invention; -
Figure 3 is a cross sectional schematic view of an impeller according to an embodiment of the invention; and -
Figure 4 is a cross sectional schematic view of a fan comprising a cover plate and an impeller according to an embodiment of the invention. -
Figure 1 shows a cross section of a circular cover plate for a fan according to one embodiment of the present invention. Thecover plate 2 comprises amain body 4 and adetachable face plate 6. Theface plate 6 comprises a cylinder which is detachably connected to themain body 4 by means ofclips 16. Theface plate 6,main body 4 and coverplate 2 as a whole are substantially rotationally symmetric around a central axis C. - The
main body 4 comprises a radiallyouter portion 8 with a hollow frustroconical shape and a radiallyinner portion 10. The radiallyinner portion 10 comprises aprojection 12 that projects and narrows along the central axis C on a rear side of thecover plate 2 to acentral point 14. Theprojection 12 is substantially conical in shape. The profile of theprojection 12 comprises a gradient that varies smoothly from a shallower gradient at its base to a steeper gradient as it nears thecentral point 14. - The
inner portion 10 also comprises theclips 16, which detachably connect theface plate 6 to themain body 4 on a front side of thecover plate 2, opposite to the rear side. When theface plate 6 is connected to themain portion 4, a contiguousfront surface 18 is formed, comprised of front facing surfaces of theouter portion 8 and theface plate 6. - The cover plate also comprises a contiguous
inner surface 19, comprised of rearward facing surfaces of themain body 4 and theinner portion 10, that curves smoothly from a radially outermost edge to thecentral point 14. - The operation of the
cover plate 2 described above will now be described with reference toFigure 2 which shows a cross sectional schematic view of a fan comprising thecover plate 2. - A
fan 20 comprises thecover plate 2 ofFigure 1 , a mountingplate 22 and animpeller 24, all of which are substantially rotationally symmetric and lie with their axis of rotational symmetry on a central axis C.The mounting plate 22 comprises a central cavity in which theimpeller 24 is disposed, and thecover plate 2 is disposed in front of both of the mountingplate 22 and theimpeller 24, such that theinner surface 19 of thecover plate 2 faces both the mounting plate and theimpeller 24. The taperingprojection 12 of thecover plate 2 projects away from theinner surface 19 towards theimpeller 24. Although not illustrated inFig. 2 , thecover plate 2 is rigidly connected to the mountingplate 22. - The
cover plate 2 is spaced away from the mountingplate 22 such that aninlet gap 26 is formed at the edge of thefan 20, between a radially outermost edge of thecover plate 2 and the outer edge of the mountingplate 22. - The mounting plate 22 (and hence the rest of the fan 20) is attached to a fixed surface 28 (e.g. a wall) which comprises a cylindrical duct 30 (e.g. a ventilation duct). The
cylindrical duct 30 lies with its axis of rotational symmetry on the central axis C, such that it is aligned with the central cavity of the mountingplate 22. Thefront surface 18 of thecover plate 2 faces away from the fixedsurface 28 and defines the front of thefan 20. Thecover plate 2 has a larger diameter than the mountingplate 22 andimpeller 24 such that, when thefan 20 is mounted as described, the mountingplate 22 andimpeller 24 are not visible from the front. - The
impeller 24 comprises a plurality ofblades 32, and in use, theimpeller 24 is driven to rotate about the central axis by a driving means (e.g. a motor, not shown). As theimpeller 24 rotates, the resultant motion of theblades 32 causes air surrounding thefan 20 to be drawn through theinlet gap 26, through theimpeller 24 and into theduct 30, illustrated here byair flow paths 34. - The profile of the
projection 12 smoothly guides the air flowing in from theinlet gap 26 perpendicularly away from thecover plate 2 towards theimpeller 24, reducing turbulence caused by air flowing from opposite edges of thefan 20 meeting at the centre. The reduction in turbulence due to the shape of thecover plate 2 means that the same volume of air flow can be provided while producing less noise, using less energy and with asmaller inlet gap 26 than would be required with a conventional cover plate. - Turbulence may be further reduced, and efficiency further increased by providing a specially shaped impeller with a tapering projection similar to that of the cover plate, as illustrated in
Figure 3 . -
Figure 3 shows animpeller 100 that comprises ahub 102 and a plurality ofblades 104. Theimpeller 100 is a mixed flow type impeller wherein theblades 104 extend radially and forwards from thehub 102. Theimpeller 100 is substantially rotationally symmetric about a central axis C and comprises acentral drive connector 105, disposed on the central axis C, to which a drive means (not shown) may be connected to rotate theimpeller 100 about the central axis C. - The
impeller 100 comprises an inlet side and an outlet side, and thehub 102 comprises a taperingprojection 106, rotationally symmetric about the central axis C, on the inlet side that narrows as it projects forwards away from thehub 102 to acentral point 108 that lies on the central axis C. The taperingprojection 106 has a curved profile that varies smoothly from a shallower gradient nearest to the outlet side to a steeper gradient as it nears thecentral point 108. -
Figure 4 shows afan 120 that comprises thecover plate 2 ofFigure 1 , a mountingplate 22 and theimpeller 100 ofFigure 3 , all of which are substantially rotationally symmetric and lie with their axis of rotational symmetry on a central axis C. As with the fan illustrated inFigure 2 , the mountingplate 22 comprises a central cavity in which theimpeller 100 is disposed, and thecover plate 2 is disposed in front of both of the mountingplate 22 and theimpeller 100, such that theinner surface 19 of thecover plate 2 faces both the mountingplate 22 and theimpeller 100. - As before, the
cover plate 2 is spaced away from the mountingplate 22 such that aninlet gap 26 is formed at the edge of thefan 120, between a radially outermost edge of thecover plate 2 and the outer edge of the mountingplate 22. The fan is mounted to a fixed surface 28 (e.g. a wall) such that the mountingplate 22 andimpeller 100 are not visible from the front. - In use, the
impeller 100 is driven to rotate about the central axis C by a driving means (e.g. a motor, not shown) connected to the drivingconnector 105. As theimpeller 100 rotates, the resultant motion of theblades 104 impels air surrounding thefan 120 through theinlet gap 26, through theimpeller 100 from the inlet side to the outlet side and into theduct 30, illustrated here by air flow paths 134 (illustrated here on only one side of the fan, for clarity). - The profile of the
projection 12 of thecover plate 2 smoothly guides air flowing in from theinlet gap 26 perpendicularly away from thecover plate 2 towards theimpeller 24, and the taperingprojection 106 of theimpeller 100 then smoothly guides air towards the outside of theimpeller 100. This reduces turbulence caused by air from opposite sides of thefan 120 meeting at the centre, and also improves the utilisation of the entire length of theblades 104 by pushing air out to the radial extremities of theimpeller 100. This has the effect of increasing the amount of air that theimpeller 100 can move for a given size and rotational speed. - The
central point 14 of thecover plate 2 and thecentral point 108 of theimpeller 100 are proximal, such that they are separated by only a small gap. This reduces the chances of cross-flow and turbulence arising at the gap. - It will be appreciated by those skilled in the art that the invention has been illustrated by describing one or more specific embodiments thereof, but is not limited to these embodiments; many variations and modifications are possible, within the scope of the accompanying claims.
Claims (15)
- A domestic ventilation fan (120) comprising:a cover plate (2) comprising an outer surface (18) and an inner surface (19), wherein the inner surface (19) comprises a tapering projection (12) that projects and narrows away from the outer surface (18), having a shape that tapers from a wide base towards a point; andan impeller (100) comprising an axis of rotation (C) and a hub (102); wherein the impeller (100) comprises an inlet side and an outlet side;characterised in that the hub (102) comprises a tapering projection (106) on the inlet side that narrows as it projects away from the hub (102), having a shape that tapers from a wide base towards a point;
wherein the cover plate (2) is positioned such that the tapering projection (12) of the cover plate (2) is aligned with the axis of rotation (C) of the impeller (100). - A domestic ventilation fan (120) as claimed in claim 1, wherein the tapering projection (12) of the cover plate (2) is rotationally symmetric about a central axis (C).
- A cover plate as claimed in claims 1 or 2, wherein the tapering projection has a curved profile that varies in gradient.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering projection (12) of the cover plate (2) has a profile with a shallower gradient nearer to the outer surface (18) and a steeper gradient further away from the outer surface (18).
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the cover plate (2) comprises a substantially planar region, and wherein the tapering projection (12) of the cover plate (2) projects along a projection axis which is perpendicular to the planar region.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering projection (12) of the cover plate (2) has an axial extent of no more than 8 cm, preferably no more than 6 cm, more preferably no more than 5 cm.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering projection (12) of the cover plate (2) has a width of no more than 20 cm, preferably no more than 15 cm, more preferably no more than 10 cm.
- A domestic ventilation fan (120) as claimed in any preceding claim, the cover plate (2) comprising a main portion (4) and a detachable portion (6), wherein the detachable portion (6) forms part of the outer surface (18).
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the inner surface (19) comprises a section which is substantially parallel to the outer surface (18).
- A domestic ventilation fan (120) as claimed in any preceding claim, the cover plate (2) comprising one or more drip holes.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering projection (106) of the impeller (100) is symmetrical around the rotational axis (C) of the impeller (100).
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the axial extent of the impeller (100) is greater than the radius of the hub (102).
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the impeller (100) is a mixed flow impeller.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering projection (106) of the impeller (100) and the tapering projection (12) of the cover plate (2) taper away from one another.
- A domestic ventilation fan (120) as claimed in any preceding claim, wherein the tapering portion (106) of the impeller (100) and the tapering projection (12) of the cover plate (2) are separated by no more than 2mm.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1717842.7A GB2568234B (en) | 2017-10-30 | 2017-10-30 | Domestic ventilation fan with tapering projections for reducing turbulence |
PCT/IB2018/058508 WO2019087078A1 (en) | 2017-10-30 | 2018-10-30 | Cover plate for a fan, impeller and fan therewith |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3704385A1 EP3704385A1 (en) | 2020-09-09 |
EP3704385B1 true EP3704385B1 (en) | 2023-06-07 |
Family
ID=60580288
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18807706.9A Active EP3704385B1 (en) | 2017-10-30 | 2018-10-30 | Fan |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3704385B1 (en) |
GB (1) | GB2568234B (en) |
WO (1) | WO2019087078A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108444028B (en) * | 2018-04-03 | 2023-09-08 | 同济大学 | Two-way reverse radian boundary layer separation-free fan outlet flow guiding device |
WO2021164567A1 (en) * | 2020-02-19 | 2021-08-26 | 应辉 | Fan |
CN111637530B (en) * | 2020-06-03 | 2021-11-09 | Tcl空调器(中山)有限公司 | Volute tongue, air conditioner indoor unit and air conditioner |
CN112032083B (en) * | 2020-09-04 | 2021-06-01 | 浙江上风高科专风实业股份有限公司 | Large-air-volume energy-saving silencing type induction fan |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2504940Y2 (en) * | 1990-04-16 | 1996-07-24 | 三菱電機株式会社 | Ventilation equipment |
JPH04324045A (en) * | 1991-04-24 | 1992-11-13 | Mitsubishi Electric Corp | Ventilation device |
JP4074891B2 (en) * | 2001-10-05 | 2008-04-16 | ハスクバーナ・ゼノア株式会社 | General blower |
JP2008190781A (en) * | 2007-02-05 | 2008-08-21 | Mitsubishi Electric Corp | Ventilating device |
JP2008275192A (en) * | 2007-04-25 | 2008-11-13 | Mitsubishi Electric Corp | Ventilation device |
JP5825791B2 (en) * | 2011-01-19 | 2015-12-02 | 三菱重工業株式会社 | Supercharger and diesel engine equipped with the same |
KR101783177B1 (en) * | 2012-06-07 | 2017-09-28 | 미디어 그룹 코 엘티디 | Oblique flow fan, oblique flow blower and console type air conditioner having same |
JP6392103B2 (en) * | 2014-12-09 | 2018-09-19 | 三菱重工業株式会社 | Sound absorber, centrifugal compressor, and supercharger |
CN205842941U (en) * | 2016-07-11 | 2016-12-28 | 南京工业大学 | Mixing smoke-discharging and ventilating system dynamic module |
-
2017
- 2017-10-30 GB GB1717842.7A patent/GB2568234B/en active Active
-
2018
- 2018-10-30 WO PCT/IB2018/058508 patent/WO2019087078A1/en unknown
- 2018-10-30 EP EP18807706.9A patent/EP3704385B1/en active Active
Also Published As
Publication number | Publication date |
---|---|
EP3704385A1 (en) | 2020-09-09 |
GB2568234A (en) | 2019-05-15 |
WO2019087078A1 (en) | 2019-05-09 |
GB2568234B (en) | 2021-12-08 |
GB201717842D0 (en) | 2017-12-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3704385B1 (en) | Fan | |
JP4756286B2 (en) | Blower | |
JP4769988B2 (en) | Blower | |
USRE49862E1 (en) | Medallion fan | |
JP5030106B2 (en) | Blower | |
KR101595474B1 (en) | A fan assembly | |
JP5442166B2 (en) | Apparatus for blowing air through a slit nozzle assembly. | |
CN100593674C (en) | Air conditioner | |
KR20180004084A (en) | Air conditioner | |
KR101931707B1 (en) | Air conditioner | |
CN106016453B (en) | Ceiling embedded air conditioner | |
EP2584201A1 (en) | Sirocco fan and air-conditioner having the same | |
KR102058064B1 (en) | Airconditioner | |
TW200530539A (en) | Integral air conditioner | |
EP3808991A1 (en) | Air treatment device, fan and centrifugal impeller thereof | |
CN108869405B (en) | Double-air-inlet centrifugal fan and range hood | |
JP6078945B2 (en) | Centrifugal blower | |
JP2016121580A (en) | Centrifugal blower | |
JPWO2018003017A1 (en) | Electric blower and vacuum cleaner | |
US20230088798A1 (en) | Blower | |
JP2016145692A (en) | Air conditioner | |
JPH0593523A (en) | Air conditioner | |
EP2090839B1 (en) | Air conditioner | |
JP3984598B2 (en) | Fan device | |
JP2006275311A (en) | Fan filter unit |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: UNKNOWN |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE |
|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE |
|
17P | Request for examination filed |
Effective date: 20200518 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
AX | Request for extension of the european patent |
Extension state: BA ME |
|
DAV | Request for validation of the european patent (deleted) | ||
DAX | Request for extension of the european patent (deleted) | ||
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
INTG | Intention to grant announced |
Effective date: 20220504 |
|
GRAJ | Information related to disapproval of communication of intention to grant by the applicant or resumption of examination proceedings by the epo deleted |
Free format text: ORIGINAL CODE: EPIDOSDIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE |
|
INTC | Intention to grant announced (deleted) | ||
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
INTG | Intention to grant announced |
Effective date: 20221116 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
RBV | Designated contracting states (corrected) |
Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE PATENT HAS BEEN GRANTED |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
P01 | Opt-out of the competence of the unified patent court (upc) registered |
Effective date: 20230503 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP Ref country code: AT Ref legal event code: REF Ref document number: 1575863 Country of ref document: AT Kind code of ref document: T Effective date: 20230615 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602018051344 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG9D |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: MP Effective date: 20230607 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: NO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230907 Ref country code: ES Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: MK05 Ref document number: 1575863 Country of ref document: AT Kind code of ref document: T Effective date: 20230607 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: RS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: HR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230908 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231007 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SM Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: RO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231009 Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231007 Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: CZ Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20231026 Year of fee payment: 6 Ref country code: DE Payment date: 20231020 Year of fee payment: 6 Ref country code: CH Payment date: 20231102 Year of fee payment: 6 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: PL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230607 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: BE Payment date: 20231019 Year of fee payment: 6 |