EP2775147A2

EP2775147A2 - A dual inlet extract fan assembly

Info

Publication number: EP2775147A2
Application number: EP14157921.9A
Authority: EP
Inventors: Colin Biggs
Original assignee: Nuaire Ltd
Current assignee: Nuaire Ltd
Priority date: 2013-03-05
Filing date: 2014-03-05
Publication date: 2014-09-10
Anticipated expiration: 2034-03-05
Also published as: EP2775147A3; EP2775147B1; GB2511518A; GB201303901D0; GB2511518B

Abstract

An extract fan assembly (10) comprises a fan and fan housing (12). The fan housing (12) comprises a plurality of walls defining an enclosure for containing the fan having an inlet opening (14) at one end. A cover plate (18) is positioned to cover the inlet opening (14) and fixed relative to the housing (12) in a spaced location from the inlet opening (14). A first air inlet is defined by the space between the cover plate and the housing. A first airflow pathway extends between the first air inlet and the fan housing (12) via the inlet opening (14). The fan assembly (10) includes a second auxiliary inlet (28) and a second airflow pathway extending between the second air inlet and the fan housing (12) that allows the spacing between the cover plate (18) and the housing (12) to be reduced while maintaining the same inlet airflow.

Description

The present invention relates to a fan assembly, and in particular to an extract fan assembly for use in a 'wet room' environment.
Extract fans for use in 'wet rooms' where water is used regularly (for example kitchens and bathrooms) are prone to damage from water ingress. It is advantageous and known to mitigate water ingress by shielding the air intake of the fan. This is typically achieved by providing a shield plate across the air inlet of the fan, which is arranged to shield against water ingress while permitting air flow into the fan. In addition, shield or cover plates advantageously improve the visual appearance of the fans by obscuring the inner workings from view, as well as providing acoustic attenuation to limit noise from the fan.
Figure 1 shows an example of a typical fan assembly 1 of the prior art. The fan assembly 1 includes a fan housing 2, a fan 4 and a shield plate 6 arranged over the inlet to the fan housing 2. To allow air to enter the fan 1, the shield plate 6 is spaced a distance d₁ away from the inlet. The size of the clearance d₁ provided must be appropriate for the air volume flow rate handled by the fan, the type of impeller used and the impeller location within the unit housing 2. If the clearance distance d₁ is insufficient this may prevent the unit from extracting the requisite quantity of air, or necessitate fan operation at a higher speed, causing increased noise generation and power demand. Alternately, if the clearance distance d₁ is too great, the ability of the fan 4 to prevent water ingress may be severely compromised. An excessive clearance distance d₁ of the shield plate will also affect the visual appearance of the fan assembly and prove unsightly.
It is therefore desirable to provide an improved extract fan assembly which addresses the above described problems and/or which offers improvements generally.
According to the present invention there is provided an extract fan assembly as described in the accompanying claims.
In an embodiment of the invention there is provided an extract fan assembly comprising a fan; a fan housing comprising a plurality of walls defining an enclosure for containing the fan having an inlet opening at one end; a cover plate positioned to cover the inlet opening and fixed relative to the housing in a spaced location from the inlet opening; a first air inlet defined by the space between the cover plate and the housing; a first airflow pathway extending between the first air inlet and the fan housing via the inlet opening. The fan assembly includes a second auxiliary inlet and a second airflow pathway extending between the second air inlet and the fan housing. The second air inlet allows the spacing between the cover plate and the housing to be reduced while maintaining the same inlet airflow. This enables the cover plate to better prevent the ingress of water into the fan housing by limiting the gap with the housing, as well as providing a more flush arrangement which is more visually appealing.
The second inlet is preferably arranged such that it is at least partially obscured from view when the fan assembly is viewed from the front.
The second airflow pathway may extend into the fan housing via the inlet opening. As such both airflow pathways utilise the same opening into the housing, which obviates the requirement for a secondary opening to be created, requiring less modification an existing housing design.
The cover plate preferably has an outwardly facing surface defining the front face of the fan assembly the second inlet is located on at least one side of the fan housing. Locating the second inlet on the side of the housing mean it is not outwardly facing and therefore obscured from view.
The second inlet preferably faces rearwardly in the opposing direction such that it is obscured from view when the fan assembly is viewed from the front. In use when the extract fan is installed it is viewed front-on and therefore a rearwardly facing inlet is entirely obscured from view when the fan assembly is viewed from the front.
The housing may include a main body section and a skirt section extending outwardly of at least one side wall of the main body with the second inlet being defined at the rear end of the skirt section between the skirt section and the main body. The skirt section forms a baffle arrangement for forming the second inlet airflow pathway while also creating a visual barrier to obscure the second inlet from view.
The skirt section preferably includes a side wall section and a front wall section having an aperture formed therein. The skirt section may be both vertically and laterally spaced from the main body section with the front wall section located between the main body section and the cover plate. The first air flow pathway extends between the first inlet and the inlet opening of the fan housing via the space between the front wall section and the cover plate and via the aperture in the front wall section and the second airflow pathway extends between the second inlet and the inlet opening of the fan housing via the space between the skirt section and the main body. As such, two separate airflow pathways are created by the skirt section which both extend to the same inlet opening of the housing. Therefore, an existing housing design may be more easily adapted, potentially in a retrofit manner, to include a secondary inlet by the addition of the skirt section.
The first airflow into the first inlet is preferably substantially parallel with the plane of the cover panel and the second airflow into the second inlet is substantially perpendicular to the first airflow in a direction towards the cover plate. The direction of the second airflow is such that the inlet is obscured from view.
The skirt section is preferably held in said spaced location from the main body by a plurality of support members which support the skirt section while permitting the passage of air through the second airflow pathway.
In another embodiment of the invention there is provided an extract fan housing comprising a plurality of walls defining an enclosure for containing a fan having an inlet opening at one end; a cover plate positioned to cover the inlet opening and fixed relative to the housing in a spaced location from the inlet opening; a first air inlet defined by the space between the cover plate and the housing; a first airflow pathway extending between the first air inlet and the fan housing via the inlet opening; and wherein the housing includes a second inlet and a second airflow pathway extending between the second air inlet and the fan housing.
The present invention will now be described by way of example only with reference to the following illustrative figures in which:

Figure 1 shows a fan assembly of the prior art;
Figure 2 shows a fan assembly according to the present invention;
Figure 3 shows a side view of the fan assembly of claim 2;
Figure 4 shows a rear view of the fan assembly of claim 2;
Figure 5 is a top view schematic of a fan assembly according to an embodiment of the invention; and
Figure 6 is a schematic representation of the airflow pathways of a fan assembly according to an embodiment of the invention.

Referring to Figure 2, a fan assembly 10 includes a fan housing 12 comprising a plurality of walls 13 and a base 15 forming an enclosure having an open outer end 17 defining a first air inlet 14 at the opposite end of the housing to the base 15. The fan housing houses a fan which is arranged to draw air through the first inlet 14 into the fan housing and to expel the air via the outlet ducting 16 which extends from an aperture formed in the base 15. A shield plate 18 is located in front of the first inlet 14 to shield the fan housing 12 from water ingress and to obscure the inside of the housing 12 from view.
As shown in Figure 2, the housing 12 has an outer edge 20 which is the outwardly facing edge of the housing 12 when installed. Here the terms 'outer' and 'inner' ends are relative terms used with reference to the end of the fan assembly which is outwardly facing in use, and the opposing inner end which is at the base of the assembly. The outer edge 2 surrounds and defines the inlet opening 14. The shield plate 18 is supported by a plurality of spigots 22 which hold the shield plate 18 a spaced distance d₂ from the outer edge 20 of the housing 12.
The outer end of the housing 12 includes a peripheral frame section 24 having a width w₁ that surrounds the inlet 14. The peripheral frame section 24 extends outwardly of the main body 26 of the housing which has a width w₂, such that the frame sections 24 defines an overhang extending past the side wall of the main body 26. A series of apertures 28 are formed at the inner rear end face of the frame section 24 which extend into the fan housing 12 defining an air pathway.
As shown in Figure 4 the frame section 24 overhangs the main body section 26 on two opposing side defining a skirt. However, this may be one side only where a lower airflow is required, or conversely more than two sides if increased airflow is required by the system specification. The frame or skirt section 24 includes at each overhanging portion a side wall 30 which is spaced outwardly in the width wise direction from the side wall 32 of the main body 26, and a roof section 34 formed by the front wall or outer face of the frame section, with the frame section 24 being spaced from the main body section 26 in the longitudinally outwards direction and held in this spaced position by a series of support tabs 35. The side wall 30 of the skirt section and the side wall 32 of the housing combine to define an airflow cavity through which the second inlet apertures 28 extend and connect with a further aperture formed at the upper edge of the main body section 26 to define a second air inlet pathway 36. The second air inlet 28 is therefore arranged on the rearwardly facing side of the skirt section 24 such that it is obscured from view when viewed from the front by the side wall 30 which forms a side skirt covering and obscuring the second inlets 28, and by the front wall section 34.
As shown in Figure 5, the fan 36 is located within the fan housing 12. A first airflow enters the fan housing 12 through the first inlet 14 in a direction substantially transverse to the longitudinal axis of the fan assembly via the gap defined around the sides of the fan assembly between the shield/cover plate 18 and the outer face of the frame section 24. A second airflow enters the fan housing 12 through the second inlet 28 in a second direction that is substantially parallel to the longitudinal axis of the fan assembly in an outwardly facing direction. The second inlet 28 provides an additional inlet area, with the fan assembly incorporating a secondary frame element 24 extending the unit facia in width and/or height. The frame section 24 allows air to enter at its rear face, between the frame section and the main body of the housing, from whence it enters the unit housing via a secondary inlet aperture. The frame arrangement is such that the secondary inlet aperture is concealed from the room occupants and also protected from adverse water ingress.
The dimensions of the first 14 and second 36 inlets are calculated so as to allow the required additional flow rate thus reducing the resistance against which the fan operates. In this way the front plate spacing may be maintained at the optimum position for its protective functions previously described.
The position and aspect ratio of these apertures is calculated so as to provide the optimum flow pattern into the fan inlet orifice.
As shown in the schematic of Figure 6, the first airflow pathway f₁ extends from first inlet 14 defined between the cover plate 18 and the front wall 34 of the skirt section 24, then via the aperture 35 formed in the front wall 34, and finally via the inlet opening 17 into the housing 12. The second airflow pathway f₂ extends from the second inlet 28 defined between the side wall 30 and the side wall 32, between the space between the inner surface of the front wall 34 and the front end of the main body 26 and via the inlet opening 17 into the housing 12.
The fan assembly design therefore provides a secondary, concealed, airflow path into the fan, whilst protecting the fan from adverse water ingress and maintaining good appearance. The design of the inlet is also arranged to optimise the flow pattern into the impeller inlets
The design of the present invention is intended for operation with centrifugal fans of all types, and axial and mixed flow fans.
Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

An extract fan assembly comprising:
a fan;

a fan housing comprising a plurality of walls defining an enclosure for containing the fan having an inlet opening at one end;

a cover plate positioned to cover the inlet opening and fixed relative to the housing in a spaced location from the inlet opening;

a first air inlet defined by the space between the cover plate and the housing;

a first airflow pathway extending between the first air inlet and the fan housing via the inlet opening; and

wherein the fan assembly includes a second inlet and a second airflow pathway extending between the second air inlet and the fan housing.
An extract fan assembly according to claim 1 wherein the second airflow pathway extends into the fan housing via the inlet opening.
An extract fan assembly according to claim 1 or 2 wherein the cover plate has an outwardly facing surface defining the front face of the fan assembly the second inlet is located on at least one side of the fan housing.
An extract fan assembly according to any preceding claim wherein the cover plate has an outwardly facing surface defining the front face of the fan assembly and the second inlet faces rearwardly in the opposing direction such that it is obscured from view when the fan assembly is viewed from the front.
An extract fan assembly according to claim 4 wherein the housing includes a main body section and a skirt section extending outwardly of at least one side wall of the main body with the second inlet being defined at the rear end of the skirt section between the skirt section and the main body.
An extract fan assembly according to claim 5 wherein the skirt section includes a side wall section and a front wall section having an aperture formed therein, the skirt section is spaced from the main body section with the front wall section located between the main body section and the cover plate, and wherein the first air flow pathway extends between the first inlet and the inlet opening of the fan housing via the space between the front wall section and the cover plate and via the aperture in the front wall section and the second airflow pathway extends between the second inlet and the inlet opening of the fan housing via the space between the skirt section and the main body.
An extract fan assembly according to any one of claims 4 to 6 wherein the first airflow into the first inlet is substantially parallel with the plane of the cover panel and the second airflow into the second inlet is substantially perpendicular to the first airflow in a direction towards the cover plate.
An extract fan assembly according to claim 7 wherein the skirt section is held in said spaced location from the main body by a plurality of support members.
An extract fan housing comprising:
a plurality of walls defining an enclosure for containing a fan having an inlet opening at one end;

a cover plate positioned to cover the inlet opening and fixed relative to the housing in a spaced location from the inlet opening;

a first air inlet defined by the space between the cover plate and the housing;

a first airflow pathway extending between the first air inlet and the fan housing via the inlet opening; and

wherein the housing includes a second inlet and a second airflow pathway extending between the second air inlet and the fan housing.
An extract fan assembly substantially as hereinbefore described with reference to, and/or as shown in figures 2 to 6.
An extract fan housing substantially as hereinbefore described with reference to, and/or as shown in figures 2 to 6.