GB2597968A

GB2597968A - Furniture

Info

Publication number: GB2597968A
Application number: GB2012556.3A
Authority: GB
Inventors: Keith Shepherd Nigel
Original assignee: Airshield Ltd
Current assignee: Airshield Ltd
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2022-02-16
Anticipated expiration: 2040-08-12
Also published as: GB202012556D0; WO2022034165A1; GB2597968B

Abstract

An item of furniture 10 comprises a flat working surface 12 and an elongate upwardly directed air extraction inlet 22 located on the working surface. The inlet leads to a flow passage that is subdivided into a plurality of narrower sub-passages. The sub-passages leading to an air pump 26 arranged to draw air into the inlet. In this way, an airflow pattern above the desk can be created which involves a laminar flow of air downwards into the inlet in a "curtain" above the inlet. Infectious particles exhaled by a person on one side of the curtain are then drawn down into the inlet instead of being projected to a person on the other side of the item of furniture. The flow passage is ideally defined by side walls (36,38; Figure 2) along the elongate length of the inlet and subdivided by least one guide vane (34, Figure 2) located between the side walls, the guide vane being spaced from each of the side walls. The inlet can be formed in the working surface with the flow passage extending through the working surface. The furniture can be a desk or a table.

Description

Furniture

FIELD OF THE INVENTION

The present invention relates to an item of furniture.

BACKGROUND ART

Furniture is in widespread use in homes, in offices, and in commercial establishments to allow people to make productive use of the space within those buildings. In offices, desks provide an area where workers can sit and carry out their work. In homes and restaurants, tables allow people to sit and eat. Other examples abound.

Often, desks, tables and similar items of furniture are arranged so that more than one person can sit at them at the same time. Office desks may be arranged in groups, with pairs of workers sitting face to face, and tables may be arranged with diners seated opposite each other. This is more social and generally more amenable, but in the light of Covid-19 is regarded as inherently undesirable since the face-to-face orientation maximises the risk of transmission of viruses and other infections in the breath of the people concerned.

Many offices and commercial establishments are erecting screens between workstations (etc), in order to block direct transmission. However, these are visually unappealing and require constant cleaning and disinfection.

CN209463549U discloses a desk with a filtered aperture in the middle, leading to a flow passageway through which air is drawn; the aim is to draw in air from the space above the desk and cleanse it of harmful gases, particulate contaminants, and dust. Our experiments show that this arrangement is ineffective for preventing transmission of viruses and infections since the airflow pattern that it creates is inadequate and unsuited to that task.

SUMMARY OF THE INVENTION

The present invention therefore provides an item of furniture, comprising a flat working surface and an elongate upwardly-directed air extraction inlet located on the working surface, the inlet leading to a flow passage that is subdivided into a plurality of narrower sub-passages, the sub-passages leading to an air pump arranged to draw air into the inlet. In this way, an airflow pattern above the desk can be created which involves a laminar flow of air downwards into the inlet in a "curtain" above the inlet. Infectious particles exhaled by a person on one side of the curtain are then drawn down into the inlet instead of being projected to a person on the other side of the item of furniture.

The flow passage is ideally defined by side walls along the elongate length of the inlet and subdivided by least one guide vane located between the side walls, the guide vane being spaced from each of the side walls. This creates two thin or narrow slots into which air can be drawn in a laminar manner.

The inlet can be formed in the working surface with the flow passage extending through the working surface, such as to ducting, filters and a pump below the working surface. Alternatively, the inlet can be located above the working surface, and the flow passage can include a conduit resting on the working surface and leading towards an edge of the working surface. The latter arrangement allows the invention to be retrofitted to a standard item of furniture.

The flow passage preferably includes a filter, and/or a UV light source directed at the air passing through the flow passage. These assist in removing infectious material from the air that is drawn into the inlet.

To help establish the correct air flow pattern, the inlet should define a flow passage that is initially long, narrow and downward. To this end, the spacing between the subdivision (or the at least one vane) and the nearest side wall is preferably no more than 30mm, the side walls and the subdivision extend downwardly by at least 100mm, and/or the space between the subdivision and the vane has an aspect ratio of at least 4 in its vertical section.

The present invention can be applied to a desk, a table, or a counter, as required. Generally, it is convenient if the item of furniture is sized to allow use of the working surface from either of two elongate sides, and the inlet is arranged along a centreline of the working surface between the two elongate sides. This allows two persons to sit and work on either side of the desk or table. Where the invention is applied to a counter, such as a reception desk of a hotel, or bank, or the like, the inlet can be offset from the centreline of the working surface between the two elongated sides, to give one person more work area than the other.

The working surface to which we refer can, for example, be the generally horizontal surface of a desk or a table, or any surface provided by the furniture over which a virtual barrier is to be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a perspective view of a desk according to a first embodiment of the present invention; Figure 2 shows a vertical lateral section of the relevant part of the desk of figure 1; Figure 3 shows a vertical longitudinal section of the relevant part of the desk of figure 1; Figures 4 and 5 show end and side views (respectively) of a table according to a second embodiment of the present invention; Figure 6 shows a vertical lateral section of the relevant part of the table of figures 4 and 5; Figure 7 shows a vertical longitudinal section of the relevant part of the table of figures 4 and 5, figure 6 being a section on A-A of figure 7; Figure 8 shows a vertical longitudinal section of an inlet for use in the present invention; Figure 9 shows a vertical lateral section of the inlet of figure 8; Figure 10 shows the airflow pattern achieved by CN209463549U, for comparison; Figure 11 shows a typical airflow pattern over a desk without the present invention being in operation; and Figure 12 shows a typical airflow pattern over a desk while the present invention is in operation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to figure 1 to 3, a first embodiment is illustrated in the form of a desk into which the present invention has been incorporated. The desk 10 has the usual work surface 12 supported by four legs 14, 16, 18 (of which three are visible), one at each corner. Other support arrangements for the desk 10 are known, such as cantilever arrangements, and these may be used in preference if desired.

A slot 20 is formed along the centreline of the desk to accommodate an air inlet 22. This includes an inlet 24 into which air is drawn by a pump arrangement 26. The air can be expelled from the pump arrangement (after filtration and/or UV treatment) via an outlet 28 at floor level (as illustrated) or via a conduit to elsewhere, such as the exterior of the building in which the desk is located.

The air inlet 22 is shown in more detail in figures 2 and 3, and includes a substantially rectangular-section duct 30 extending upwardly through the slot 20. The duct 30 is narrow in one dimension and wide in another, to fit within the slot 20 and to allow air to be withdrawn from a central band along a significant part of the length of the desk, suitable for allowing a desk worker to sit on either side of the air inlet 22 with the inlet between them in order to draw air in and inhibit the transmission of potentially infectious material from one worker to the other. The inlet is shaped so as to create an airflow pattern that is advantageous for this purpose; what is required is as close as possible to a vertical laminar flow confined to the space above the air inlet 22. To this end, the duct 30 ideally has an aspect ratio in its vertical section of at least 4, preferably higher and in the region of 5 to 7 or higher. In other words, the depth of the duct 30 before it widens substantially into a plenum 32, located beneath the desk surface 12, is at least 4 times the width of the air flow passage that the air is moving through, and ideally 5 to 7 times that width. This ensures that the air is drawn from the space directly above the inlet opening 24, rather than more widely, creating a downward-moving airflow pattern that extends a significant distance above the inlet opening 24 and is able to 'catch' potentially infectious material before it can move from one side of the desk to the other.

To maintain the aspect ratio needed for this flow pattern whilst also allowing a sufficient volume of air to be drawn, the duct 30 is divided into two (in this case) adjacent sections by a guide vane 34 which (in this embodiment) sits symmetrically between the two long side walls 36, 38 of the duct 30. This divides the duct into two side-by-side sections, thus doubling the aspect ratio of the air flow passage whilst maintaining substantially the same total cross-sectional area and depth. In this way, a sufficient volume of airflow can be ensured whilst maintaining its directionality, in a duct whose dimensions are small enough to fit unobtrusively into a desk or similar item of furniture. The guide vane 34 is shown as supported by a spar 40 which holds it in its central position and hinders dislocation or damage of the guide vane 34; this may or may not be necessary depending on the design and the material used for the duct 30 and guide vane 34.

As mentioned, the duct 30 leads to a plenum chamber 32 which can be conveniently located beneath the desk and out of sight. This can be connected to ducting 42 leading to the air extraction pump via one or more filters and UV treatment chambers to remove and/or eliminate infectious agents. A trim section 44 is fitted to the side of the duct 30 in order to provide a neat appearance and hide the cut slot 20. Figure 3 shows a relatively short length of duct 30 which may be suitable in some situations; in others, the duct 30 may be made longer or several such ducts may be placed in a line or other array. Longer ducts may include more than one spar 40, if required.

Figure 4 to 7 show a second embodiment. As opposed to the first embodiment of figures 1 to 3, this arrangement is suitable for retro-fitting to an existing item of furniture, in this case a table 50 such as a dining table for use in a home or a restaurant, or any other item of furniture with a substantially flat or level tabletop 52. As with the desk 10, the tabletop 52 is shown being supported by four legs 54, 56, 58 but may be supported in any other manner such as more or fewer legs, or a cantilever arrangement, or solid end pieces, or by affixing to another item or wall.

Instead of a slot through the tabletop 52, this embodiment includes an elongate plenum chamber 60 which sits on top of the tabletop 52, extending longitudinally along its centreline between people sitting on either side of the table. The plenum chamber 60 extends over an edge of the tabletop 52 to a pump arrangement 64 located alongside the table 50. As with the first embodiment, the air can be expelled from the pump arrangement 64 (after filtration and/or UV treatment) via one or more outlets 66 at floor level (as illustrated) or via a conduit to elsewhere, such as the exterior of the building in which the table 50 is located.

The plenum chamber 60 has an air inlet 68, shown in more detail in figures 6 and 7, which includes a substantially rectangular-section duct 70 extending upwardly from the plenum chamber 60 to the air inlet opening 68. The duct 70 is as described in relation to the first embodiment, and is thus narrow in one dimension and wide in another to allow air to be withdrawn from a central band along a significant part of the length of the table. As in the first embodiment, the duct 70 is divided into two (in this case) adjacent sections by a guide vane 72 which (in this embodiment) sits symmetrically between the two long side walls 74, 76 of the duct 70. The guide vane 72 is also shown as supported by a spar 78, which both holds the guide vane 72 in its central position, hindering dislocation or damage, and also creates a solid divide within the passageway to define separate internal passages to balance the air flow between the parts of the inlet which are furthest and nearest to the pump.

A trim section 80 is fitted to one end of the plenum chamber 60 in order to provide a neat appearance. Figure 7 shows a relatively short length of duct 70 which may be suitable in some situations; in others, the duct 70 may be made longer or several such ducts may be placed along the length of the plenum chamber 60. Longer ducts may include more than one spar 78, if required, and longer and/or multiple ducts 70 may be provided with separate internal flow passages within the plenum chamber 60 so that the airflow created by the pump 64 is evenly distributed between them.

The ducts 30, 70 of the above-described embodiments are shown as straight-sided but in practice may diverge slightly in the direction of air flow.

The features that also help create the necessary pattern of air flow include the substantially uninterrupted aerodynamic ducting with variable cross sectional area to the extraction fans, ensuring a smooth flow of air through from the array of nozzles and guide vanes, that create the vertical downdraught and produce an air barrier between each side of the device. The collected air is directed though a local or remote filtration and/or UV system to remove viruses. The extraction pump can be provided by twin multi-flow axial fans with a combined maximum flow of 490 m3/hr, and can be connected via 100mm dia. flexible ducting to a manifold and then to the ducting and intake with the vanes and nozzles. Other types and specifications of fans can be used as long as they have a high volume flow rate that is maintained with little back pressure from the reducing duct and nozzle arrangement. This should be adequate to maintain a flow rate of at least around 250-300m3/hr at the vent, taking into account the losses arising in the ducting and other flow passages.

Figures 8 and 9 show an inlet and duct 100 according to a further embodiment of the invention, which may be incorporated within the first or the second embodiments above. Two 226mm-long, 22mm-wide slots 102, 104 are defined either side of the central guide vane 106 and bounded by the side walls 108, 110. The upper parallel-sided part of the duct 100 is 55mm deep and is followed by a further 55mm deep section which widens longitudinally, thus maintaining substantially the same 22mm width (laterally) of the flow passages but offering less resistance to flow. At the base of this section, the end walls 112, 114 of the duct 100 become parallel again for a further 50mm and the side walls open up a little to widen the flow passages to 26mm each. Thus, the aspect ratio of the flow passages is between (55+55)/22, i.e. 5, and (55+55+50)/24, i.e. 6.7 (24mm being an average width of the flow passages).

The guide vane 106 is again supported by a spar 116 which in this instance extends vertically for part of the initial parallel-sided section of the duct 100.

The aspect ratio of the duct 30 below the inlet 24 creates the necessary airflow, as discussed above. The airflow is in the form of a downwardly-moving "air curtain" that descends into the inlet 24. For comparison, Figure 10 shows the airflow created by the arrangement disclosed in CN209463549U; the wide aperture 120 combined with a shallow duct 122 created merely as a result of the thickness of the desktop 124 gives an aspect ratio of between 1 and 2, and means that the airflow 126 is largely horizontal across the surface of the desktop 124 before descending into to duct 122.

Figures 11 & 12 provide a schematic illustration of the results of experiments which we have carried out as to the airflow pattern that is achieved. An aerosol spray was used to simulate the exhaled air of an individual sitting on one side of the desktop 130. This was sprayed from the approximate location 132 of the individual's mouth and nose, towards the location 134 of a hypothetical person sitting on the other side of the desktop 130. The general path of the aerosol spray 136 was visible and could be seen to move from one side of the desk to the other. Some dispersion is observed, but a significant amount of the spray reaches the other side.

Figure 12 shows the effect of activating the air pump of the present invention and drawing air into the inlet 138. The spray 136 is drawn down into the inlet 138, with a noticeable change in direction when it moves into the region 140 above the inlet 138. As a result, little or none reaches the location 134 of the hypothetical person sitting opposite. From this, we can conclude that the "wall" of air in the region 140 above the inlet 138 is moving downwards in a laminar flow.

Generally, the precise dimensions and detail shape of the opening can be tailored to a specific context, as can the flow rate. Increasing the power of the fans increases flow, but this also tends to creates a lower nozzle pressure (i.e. the below-atmospheric air pressure which draws the air in), and we have noted that the result of too low a pressure is that it tends to increases the air draw from the sides at the opening of the nozzles. The resulting edge turbulence narrows the effective size of the opening and in fact reduces the laminar flow from above. A degree of optimization may therefore be needed. Optimising the flow may also be achieved by adjusting the subdivision of the inlet, for example by providing more than the single central vane illustrated and described above, or by building the flow passageway from a number of narrower conduits, such as a collection of circular-section pipes arranged in an array.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims

CLAIMS1. An item of furniture, comprising a flat working surface and an elongate upwardly-directed air extraction inlet located on the working surface, the inlet leading to a flow passage that is subdivided into a plurality of narrower sub-passages, the sub-passages leading to an air pump arranged to draw air into the inlet.
2. An item of furniture according to claim 1 in which the flow passage is defined by side walls along the elongate length of the inlet and is subdivided by least one guide vane between the side walls, the guide vane being spaced from each of the side walls.
3. An item of furniture according to claim 1 or claim 2 in which the inlet is formed in the working surface and the flow passage extends through the working surface.
4. An item of furniture according to claim 1 or claim 2 in which the inlet is located above the working surface, and the flow passage includes a conduit resting on the working surface and leading towards an edge of the working surface.
5. An item of furniture according to any one of the preceding claims in which the flow passage includes a filter.
6. An item of furniture according to any one of the preceding claims in which the flow passage includes a UV light source directed at the air passing through the flow passage.
7. An item of furniture according to any one of the preceding claims in which the spacing between the subdivision and the nearest side wall of the inlet is no more than 30mm.
8. An item of furniture according to any one of the preceding claims in which the side walls of the inlet and the subdivision extend downwardly by at least 100mm.
9. An item of furniture according to any one of the preceding claims in which the space between the side walls of the inlet and the subdivision has an aspect ratio of at least 4 in its vertical section.
10. An item of furniture according to any one of the preceding claims, being a desk.ii.
An item of furniture according to any one of claims 1 to 6, being a table.
12. An item of furniture according to any one of the preceding claims, sized to allow use of the working surface from either of two elongate sides, in which the inlet is arranged along a centreline of the working surface between the two elongate sides.
13. An item of furniture according to any one of claims 1 to 11, sized to allow use of the working surface from either of two elongate sides, in which the inlet is offset from the centreline of the working surface between the two elongated sides to give one person more work area than the other.