Field of the invention

The present invention relates to a filter for a raised ventilation flooring structure. The present invention further relates to a raised ventilation flooring structure comprising such a filter.

Background art

Ventilation systems providing a substantially vertical flow in a room, such as the systems developed by the applicant, and described in NL2025707, PCT/NL2021/050343 and NL2028139, have proven to greatly reduce the risk of germs and viruses spreading between persons occupying the same room, compared to Class A ventilation systems. This makes these vertical ventilation systems particularly interesting for implementing in classrooms, gyms, offices, and other spaces used by multiple people at the same time.

However, through use of these spaces, their floors will naturally be soiled by filth, including dust, debris such as sand, crumbs and any other material falling onto the floor, and even liquids from spills. Through the permeability of the floor, this filth can easily penetrate into the flooring system, where it is difficult to reach for cleaning up. When present in sufficient amounts, the filth can start to (partially) clog the floor, thereby negatively impacting the verticality of the flow from the floor. In NL2028139, the applicant already presented an improved flooring system in which the ingress of water and dirt into the space below the flooring panels is prevented. However, the thorough cleaning of the flooring panels and supporting structural elements themselves, which collect the dust and dirt, remained a laborious task.

It is an object of the invention to provide for easier thorough cleaning of raised flooring of ventilation systems.

Summary of the invention

Hereto, in a first aspect of the invention, a filter for collecting filth falling through a permeable surface of a raised ventilation flooring structure is provided, the filter comprising: a filter frame, having a width and a length that are substantially equal to a tile of the permeable surface of the raised ventilation flooring structure, said width and length defining a filter surface, a filter cloth, comprising a gas permeable fabric, which is held by the filter frame and spanning substantially the entire filter surface, and means for attachment adapted for attaching the filter frame to the raised ventilation flooring structure, such that, when attached, the filter surface is substantially parallel to the permeable floor surface at a predetermined vertical distance below the permeable floor surface. The filter cloth of the filter of the invention allows the filtering of an air flow that is used for ventilating a room, before the air flow passes through a raised and permeable floor of the room's ventilation system. It means that cleaner air is be provided into the living space of a room above the permeable floor. A verticality of the air flow is not altered as the filter and the permeable floor are substantially parallel. The filter of the invention further

SUBSTITUTE SHEET (RULE 26) provides means for attachment which allows its easy installation and fixing at a predetermined and substantially constant distance under the raised permeable floor.

In an embodiment, the filter cloth further comprises one or more filth reservoirs. With one or more filth reservoirs, the filter cloth further collects filth and therefore prevents it to fall in the space under the filter. Filth is stopped and maintained at a predetermined distance below the permeable floor surface, such that said filth remains within reach for a normal vacuum cleaner. As a result, normal cleaning operations of the floor will be sufficient to prevent filth from building up within the permeable floor surface and/or collecting in the space below said permeable floor surface.

In an embodiment, the gas permeable fabric is provided with one or more folds, wherein the one or more folds form the one or more filth reservoirs. Folds in the filter surface provide one or more recesses in the filter fabric, where a recess may collect a volume of filth corresponding to the volume of the recess.

In an embodiment, the one or more filth reservoirs are made of a gas tight material and are provided on or at an upper side of the gas permeable fabric, for collecting filth. When it is made of a gas tight material, the filth reservoir may collect more filth as most of the filth can not pass through the reservoir. As the filth reservoir is placed on an upper side or on the filter cloth, it contacts the filth first, before the filter cloth does and the filter cloth may be maintained clean.

In an embodiment, the one or more filth reservoirs are attached to an upper surface of the filter cloth, preferably with glue or thermal bonding. Manufacturing of the filter cloth of the invention is simple in that the filth reservoirs can be added to any filter cloth, as separate entities, using methods known to the person skilled in the art.

In an embodiment, the one or more filth reservoirs are located adjacent the filter cloth, at a minimal distance such that no contact exists between the filth reservoirs and the filter cloth. Filth reservoirs may be added at a distance from the filter cloth in order to collect filth while minimizing a contact of filth with the filter cloth. As a result, less filth passes through the filter cloth and/or less filth damages the filter cloth.

In an embodiment, each of the one or more filth reservoirs has a width and/or a length smaller than a width and/or a length of the filter cloth. The filth reservoirs may be minimized in size not to affect the flow of air through the ventilation flooring system, and provide just enough surface area to allow the collection of filth.

In an embodiment, at least one of the filth reservoirs is gutter-shaped, having a substantially V-shaped cross-section, wherein each leg wiz, wzz of the cross-section is between 7 and 14 mm, preferably between 9 and 11 mm, and a width w _z of the cross-section is between 12.3 and 19.1 mm, preferably between 17 and 19 mm. Having a gutter-shaped reservoir allows collection of a volume of filth. That filth is less likely to drop outside of the reservoir as it is maintained between the walls of the gutter. With such dimensions, efficient filth collection could be observed.

SUBSTITUTE SHEET (RULE 26) In an embodiment, at least one of the filth reservoirs has a cone-like shape. Cone-shaped reservoirs allow both the collection and the cleaning of filth, easily accessible in the volume of the cone by a vacuum cleaner at a distance from the cone.

In an embodiment, at least three filth reservoirs are provided, said filth reservoirs being evenly spaced over the filter surface. By providing evenly spaced filth reservoirs, more filth can be collected, and less damage may be done on the filter cloth.

In an embodiment, the filter frame comprises three or more connector elements adapted for attachment of the filter surface to a lower side of a permeable floor tile of the raised ventilation flooring structure. The filter frame can be easily supported by the permeable floor, using a reduced number of attachment means. As a result installation of the filter is simplified.

In an embodiment, the gas permeable fabric is F9 fabric, according to DIN EN 779:2012 and/or ISO 16890: 2016. The F9 fabric has a filtering efficiency of 95 to 98% , without requiring additional air-pressure for the air which has to pass therethrough. A filter cloth of the F9 fabric provides for highly efficient filtering of the air flow before it passes through the permeable filter. As a result, a very clean air flow ventilates the room. F9 fabric provides superior filtering for viruses, bacteria and other small particles such as pollen. However, tests of the claimed filters in a ventilation flooring as further described have shown that sufficient filtering can also be achieved with G3 fabric, at a much lower cost.

In a second aspect of the invention, a raised ventilation flooring structure is provided, the raised ventilation flooring structure comprising a permeable floor surface, and a floor frame, which floor frame is arranged to hold the permeable floor surface at a predetermined vertical distance from the floor of a room, wherein said flooring structure further comprises the filter of the first aspect of the invention, wherein the filter frame is attached to the raised ventilation flooring structure with the filter surface substantially parallel to the permeable floor surface at a predetermined vertical distance below the permeable floor surface in the floor frame. The raised ventilation structure of the invention comprising a filter surface which allows for cleaning of the air before it enters the room that requires ventilation. The directionality of the airflow is also not altered due to the filter having a similar orientation as the permeable floor. The structure is further ready to install, as the filter frame is already attached to the upper permeable floor. An additional benefit of providing the raised ventilation flooring structure with the filter, is that the filters together form a permeable layer under the permeable floor surface that has been found to act as a pressure equalizer, i.e. the filters let air flow through at a substantially equal rate over their entire (joint) surface. As a result thereof, the permeable floor surface itself does not need additional adjustments, such as a predetermined variation in through-holes and/or valves, to ensure a vertical air-flow entering the room at a substantially equal rate over the entire floor surface.

In an embodiment, the predetermined vertical distance d between the filter cloth and a bottom side of the permeable floor surface is at most 8 mm, preferably at most 7 mm, most preferably at most 6 mm. Tests have shown that the smaller the distance, the more sand can be removed from the filter surface by using a regular vacuum cleaner to clean the upper surface of the permeable flooring, as one would normally do to clean floors. During said tests, a flooring

SUBSTITUTE SHEET (RULE 26) system as presented in NL2028139 was provided with a filter surface and two series of tests were run, one with 20 grams of sand being provided onto the filter surface prior to vacuum cleaning, and one with 6 grams of sand being provided. From 8 mm distance and less, the amount of sand removed by vacuum cleaning became more and more satisfactory, with an optimum at 6 mm.

Brief description of the drawings

Embodiments of the present invention will be described by way of example, with reference to the attached drawings, in which:

Fig. 1 shows a perspective view of a room in which a raised ventilation flooring structure according to the invention has been installed,

Fig. 2 shows an enlarged sectional view of the raised ventilation flooring structure according to the invention,

Fig. 3A shows a perspective view of a filter cloth of the filter surface of the raised ventilation flooring structure according to a first embodiment of the invention,

Fig. 3B shows a perspective view of a filter cloth of the filter surface of the raised ventilation flooring structure according to a second embodiment of the invention,

Fig. 3C shows a perspective view of a filter cloth of the filter surface of the raised ventilation flooring structure according to a third embodiment of the invention,

Fig. 3D shows a perspective view of a filter cloth of the filter surface of the raised ventilation flooring structure according to a fourth embodiment of the invention,

Fig. 4 shows an illustration of the cleaning steps of a raised ventilation flooring structure according to the invention.

Description of embodiments

Fig. 1 shows a perspective view of a room 1 provided with a raised ventilation flooring structure 35 according the invention. The room 1 is made of a floor 2, a ceiling 7 and walls 3, 4, 5, 6 extending between the floor 2 and the ceiling 7. The floor 2 has a surface area L x w defined by a length L and a width w of the floor 2. The ceiling 7 is arranged at a height H above the floor 2. The room further comprises a lower gas permeable ceiling 8 arranged at a height H3 where H3 < H. The raised ventilation flooring structure 35 comprises a permeable floor surface 15 and a filter surface 25, both raised at a height above the floor 2. The permeable floor surface 15 and the filter surface 25 are positioned at heights Hl and H2, respectively, above the original floor, where H2 < Hi < H. A floor frame holds the permeable floor surface 15 at the distance Hi. The floor frame may comprise adjustable supports 20. Preferably the adjustable supports 20 are positioned at regular intervals so that a stability of the permeable floor surface 15 is ensured. In other embodiments the floor frame may comprise other means of maintaining the permeable

SUBSTITUTE SHEET (RULE 26) floor surface 15 at the predetermined height Hi. The filter surface 25 is held substantially parallel to the permeable floor surface 15 at the height H2 and attached to the permeable floor surface 15 via attachment means (not shown). An example of attachment means is shown in Fig. 2, comprising at least three connector elements 28, 29, 30. Both the permeable floor surface 15 and the filter surface 25 allow the passage of air to ventilate a room. The room 1 further comprises an air supply inlet and an air supply outlet (not shown) forming part of the room ventilation system. The air supply inlet forms the source of an air flow near the floor 2 directing the air flow in an upward direction 9 towards the lower gas permeable ceiling 8 through the raised ventilation flooring system 35. The air supply outlet is placed at or near the ceiling 7, for instance between the lower gas permeable ceiling 8 and the ceiling 7 for air to exit the room 1 along an exit direction 10. As known to the skilled person in the art, such ventilation systems may comprise one or more air filters (not shown) near the inlet, such as F9 fabric filters, according to DIN EN 779:2012, to filter the air prior to air arriving at the ventilation flooring structure. The permeable floor 15 covers the surface area of the original floor 2. Because it covers the original floor 2 and offers a walking surface in the room 1 to the individual 70 in the room 1, the permeable floor surface 15 constitutes a new and raised floor. The shown permeable floor surface 15 comprises a large tile 19 interrupted by a plurality of through-holes in the surface of the tile. The large tile comprising gas tight material or material with low gas permeability is made permeable through the provision of the through-holes, to allow sufficient passage of air. In other embodiments the permeable floor surface 15 may be made of a plurality of smaller tiles. In other embodiments, the tiles of the permeable floor surface may also comprise a gas tight material made permeable through the provision of through-holes. Alternatively gas tight tiles may be fit into a permeable floor surface by leaving one or more gaps between adjacent tiles, through which air can flow. A sufficient air flow for ventilation may also be provided in tiles of a gas permeable material by the provision of the through-holes. The through-holes are shown to be cross-shaped but it will be understood that other embodiments may have through-holes of any shape, such as a circular shape. The number of through holes per cm ² and/or size of the through holes shown may vary and is adapted as a function of a distance from the air supply inlet. Preferably the air entering the room and travelling upwards through the raised ventilation flooring system 35 has substantially the same flow rate over the whole surface area of the permeable floor 15 due to a substantially uniform hole pattern. This causes a vertical laminar air flow ventilating the room. The surface of the lower gas permeable ceiling 8 preferably comprises the same through hole pattern as the permeable floor surface 15. This allows the vertical laminar air flow to be maintained substantially vertical and laminar over the entire height of the room between the permeable floor surface 15 up to the original ceiling 7 near which the air exits the room.

Fig. 2 shows an enlarged sectional view of a raised flooring structure 35 of the invention installed on a floor 2 of the room. The raised ventilation flooring structure 35 comprises a permeable floor surface 15 and a filter surface 25 as shown in Fig. 1. The permeable floor surface 15 is held by adjustable supports 20 at the height H2 and comprises a plurality of through openings (eg 16, 17, 18) within the tile 19 of the permeable floor surface 15. The through openings have a dimension x _t0 that allow sufficient air flow. Preferably the dimension is chosen also allow the passage of filth and avoid that it clogs the openings. The filter surface 25 comprises a filter cloth 26 held by a filter frame 27 supporting the filter cloth 26. The filter cloth 26 may

SUBSTITUTE SHEET (RULE 26) comprise any material known to the person skilled in the art that provides gas permeability so that air may pass through it. A preferred filter cloth is a G3 or F9 filter cloth. The permeable floor surface 15 is supported by its frame 20, on the floor. The filter frame 27 is attached to the permeable floor 15 via a plurality of connector elements 28, 29, 30 extending between a top of the filter surface and a bottom of the permeable floor. The connector elements may be mushroom-shaped connector elements. Preferably the structure comprises at least three of the connector elements. The filter surface 25 further serves to collect filth falling down through the permeable floor surface 15. Filth comprises any of dry filth such as sand, paper, pencil shavings or wet filth such as spilled liquids. An exemplary situation is illustrated in which filth has traversed three through openings 16, 17, 18 to accumulate in filth stacks 40, 41, 42 on the filter surface 25 at areas Zi, Z2, Z3. The areas Zi, Z2, Z3 correspond to surface areas of the filter cloth 26 located at a vertical distance under the through-openings where the filth may fall and is collected. Due to a relatively small distance between the permeable surface and the filter surface, the probability that filth flies around is minimized and filth is mostly collected in the areas Zi, Z2, Z3.

Fig. 3A shows a perspective view of a filter cloth 26 of the filter surface of the raised ventilation flooring structure 35 according to a first embodiment of the invention. At areas Zi, Z2, Z3 which are arranged to be at strategic positions under locations where the filth traverses the upper permeable floor, the filter cloth 26 comprises strips of a gas tight material forming filth reservoirs 50, 51, 52. The strips have a length L _z and a width w _z that are preferably smaller than a length and/or width of the filter cloth 26. The reservoirs 50, 51, 52 are substantially flat as for the rest of the filter cloth 26. The gas tight material may be a rigid material such as plastics or metal. It is noted that in other embodiments the reservoirs may be have shapes that differ from strips, and may be adapted in shape depending on the surface area and shape of the through-openings in the permeable layer.

Fig. 3B shows a perspective view of a filter cloth 26 of the filter surface of the raised ventilation flooring structure 35 according to a second embodiment of the invention. At areas Zi, Z2, Z3 the filter cloth 26 comprises gutter-shaped filth reservoirs 53, 54, 55 having a substantially V-shaped cross-section and extending along a length of the filter cloth 26. The V- shaped cross section has a width w _z and comprises two legs of width wi _z and W2 _Z . The gutter shaped reservoirs are arranged in strips. It is noted that in other embodiments the gutter may be a substantially U-shaped gutter and/or not be strips. The filth reservoirs 53, 54, 55 comprise a gas tight material which may also be rigid such as plastics or metal. The gutter of the filth reservoirs 53, 54, 55 may extend slightly below a filth cloth 26 (not shown) or be held at a distance above the filter cloth 26 with or without contact point with the filter cloth 26.

Fig. 3C shows a perspective view of a filter cloth 26 of the filter surface of the raised ventilation flooring structure 35 according to a third embodiment of the invention. This embodiment shows an example where areas Zi, Z2, Z3 do not exceed a size of the corresponding through-openings. The filter cloth 26 comprises cone-like shaped filth reservoirs 56, 57, 58 regularly spaced on the filter cloth 26. The cone-shaped filth reservoirs have a substantially V- shaped cross section. The filth reservoirs 56, 57, 58 comprise a gas tight material which may also

SUBSTITUTE SHEET (RULE 26) be rigid such as plastics or metal. The gutter of the filth reservoirs 56, 57, 58 may extend slightly below a filth cloth 26 (not shown) or be held at a distance above the filter cloth 56, 57, 58 with or without contact point with the filter cloth 26.

Fig. 3D shows a perspective view of a filter cloth 26 of the filter surface of the raised ventilation flooring structure 35 according to a fourth embodiment of the invention. The filter cloth 26 is pleated and comprises a series of substantially parallel folds. The pleats or folds form a series of parallel and substantially V-shaped gutters. It is noted that in other embodiments the filter cloth 26 may comprise differently shaped gutters. The filter cloth 26 comprises at each V- shaped gutter a strip of a different material to form a filth collector gutters 59, 60, 61. The filth reservoirs 56, 57, 58 comprise a gas tight material which may also be rigid such as plastics or metal. It is noted that in other embodiments the reservoirs may be have shapes that differ from strips, and may be adapted in shape depending on the surface area and shape of the through- openings in the permeable layer.

Fig. 4 shows an illustration of the easy cleaning of a raised ventilation flooring structure according to the invention. The illustration shows the permeable floor surface 15 and the filter surface 25 arranged according to the invention. The filter surface 25 comprises a gutter-shaped filth reservoir having a width w _z , of which the bottom is at a vertical distance d under the bottom of a through-opening 16 of the permeable floor surface 15. In step 100 the permeable floor surface and the filter surface are arranged in the room to be substantially parallel. In step 110, a vacuum cleaner 65 serves to aspire the filth 80 that has accumulated into the filth reservoir. As shown in step 120 the reservoir is cleaned up, with the filth 80 aspired back through the through-opening into the vacuum cleaner 65.

SUBSTITUTE SHEET (RULE 26)