GB2269006A - A swirl diffuser - Google Patents

Abstract

A swirl diffuser comprises a deflector unit 2 and, downstream thereof, a perforated cover grille. The deflector unit 2 comprises a central boss and outer body 8. A plurality of radially arranged inclined deflector vanes 10 deflect air flowing through the apparatus. The cover grille is of sheet steel, 1 mm gauge, perforated by identical openings, which are circular, and 5 mm in diameter. The openings take up 50% of the area of the grille. The grille has a front wall 18, from each edge of which extends a narrow side wall 20. The grill is hinged to or a push-fit onto the unit 2, and is square. When fitted adjacent a corner or wall of a room, the portion(s) nearest thereto may be covered by a baffle between the grille and the unit 2. <IMAGE>

Description

VENTILATION APPARATUS This invention relates to ventilation apparatus. The invention relates in particular to so-called swirl diffusers which have inclined vanes set in a radial array.

When air passes through a swirl diffuser it is deflected outwardly in a turbulent manner which aids rapid mixing, in a room.

EP-A-128485 describes a swirl diffuser for use as the floor outlet of a ventilation system, the diffuser having an air deflector with inclined vanes, and a grid over the air deflector. The grid is a substantial part having concentric rings, between which air can pass. The rings are connected by ribs, which are inclined so as not to interfere with the air eddy, passing through the circular apertures between the rings of the grid. It is stated in EP-A-128485 that the arrangement of rings and ribs is such as not to interfere with the eddy. The geometry of the grid, in particular the substantial depth of the rings and, consequently, of the circular apertures, is such that it may be expected that an eddy will be maintained within the air, as it flows in a direction generally axial to the diffuser.Thus the swirling air flow will be substantially unidirectional, directed into the central zone of the room. This will be undesirable in many situations, especially in confined spaces with people present. As a result of this directionality, and also because the central region of the grid does not have circular apertures, there does not appear to be the possibility of air from the room being drawn into the diffuser by an induction effect, which could lead to the advantageous pre-mixing of room air and fresh air, within the diffuser. Rather, mixing of the fresh air with room air would only appear to be possible after the fresh air has left the diffuser.

In accordance with the present invention there is provided ventilation apparatus for use as a room outlet of an air flow pathway, in order to deflect air from a confined flow condition, along the pathway, to a dispersed condition, in the room, the apparatus cpmprising a deflector unit having a plurality of spaced deflector vanes arranged in a generally radial configuration about an axis, but inclined to that axis, thereby to discharge with air in directions transverse to that axis, and a cover grille over the deflector unit, the cover grille having openings whose minimum width exceeds their depth.

Preferably the minimum width of the openings exceeds their depth by a factor of at least 2, most preferably, at least 4.

Preferably, the openings comprise at least 20% of the area of the grille, most preferably, at least 40%.

Preferably, the openings constitute not more than 80% of the area of the grille, most preferably, not more than 60%.

Suitably, the grille may be a plate with perforations. The thickness of the plate may suitably be in the region 0.5-2mm.

Preferably, the minimum width of the openings may be in the range 1-20mm, preferably 3-lOmm.

Suitably, the openings are circular. Thus, in accordance with the present invention, their diameter exceeds their depth.

Very good results have been achieved by the use of a plate, having a thickness of about lmm, circular perforations 5mm in diameter, with 50% of the area of the plate constituted by the openings.

Preferably, the grille is detachable from the deflector unit, for example being hinged thereto, or a push fit thereon. Suitably the grille and/or the deflector unit has means for locating baffle members therebetween, in order to alter the flow conditions. For example, if ventilating apparatus in accordance with the invention is to be fitted adjacent to the corner of a room, it may be desirable to cover the quadrant of the ventilating apparatus which is nearest to the corner, so that all of the output of the apparatus is usefully directed.

Suitably, the grille may be of stepped form, having a front wall, which may suitably be planar, and narrow side walls, also with openings, such that when the grille is located over the deflector unit, the front wall is spaced from the outlet of the deflector unit and air may exit through the grille, via the openings in the side walls.

It has surprisingly been found that the provision of such a grille does not have a detrimental effect on the operation of the deflector unit; and may in certain circumstances be beneficial. For example, preliminary tests indicate that when the deflector unit is generally square in front elevation (as is preferred), the provision of such a grille may enhance the flow conditions adjacent to the corners thereof, in making flow from these regions more consistent with flow from elsewhere.

When apparatus in accordance with the present invention is in use, in air-conditioning apparatus, air exits from the apparatus in peripheral directions, generally transverse to the deflector unit. Moreover, the construction of the apparatus suitably enables room air to be drawn into the apparatus, through the central region of the grille, by an induction effect. Thus, the process of mixing fresh air with room air starts within the apparatus. Air exits the apparatus in a highly turbulent, swirling manner, giving further rapid mixing within the room, without the air being blown into the room as a deeply penetrating column.

The manner in which the apparatus of the present invention achieves good mixing, whilst avoiding draught effects, makes it particularly suitable for use in cramped environments, for example as an air outlet in a railway carriage.

In accordance with a second aspect of the present invention there is provided air-conditioning apparatus comprising a ventilating apparatus in accordance with the first aspect of the present invention. Suitably, the ventilating apparatus serves as a room outlet located in a wall or ceiling of a room.

A grille for use in apparatus in accordance with the present invention can be manufactured easily and cheaply, as compared with the grid described in EP-A-128485.

Within the technical parameters mentioned above, there is considerable freedom in designing suitable grilles, and they may be made in such a way that they effectively screen from view the somewhat unsightly deflector units located beneath them. For such reasons, as well as for the technical benefits of the apparatus in accordance with the present invention, the apparatus may find applications in high specification offices in which architects and designers may previously have been reluctant to specify swirl diffusers.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows ventilation apparatus in front elevation, partially cut away; and Fig. 2 shows the ventilation apparatus of Fig. 1, half in cross section and half in side elevation.

The ventilation apparatus comprises a deflector unit 2 and, downstream thereof, a perforated cover grille 4.

The deflector unit 2 comprises a central boss 6, an outer body 8, generally circular in section and, secured between the boss 6 and the body 8, a plurality of deflector vanes 10. The deflector vanes are generally radially arranged about the boss but are inclined, so that air leaves the deflector unit in directions approximately shown by the arrows B in Fig. 2.

On the downstream side of the deflector unit the outer body is flared outwards at 12, leading to a rectangular face wall 14, having a step 16 around its periphery to serve as locating and retaining means for the grille 4.

The cover grille 4 is of sheet steel, lmm gauge, perforated by identical openings, which are circular, and 5mm in diameter. For convenience and clarity, only a small proportion of the openings is shown in the drawings.

The openings take up 50% of the area of the grille. The grille has a front wall 18, from each edge of which extends a narrow side wall 20, the side walls having been formed by bending the sheet. The side walls 20 are perforated in the same manner as the front wall.

The grille is removably located in place using the resilience of the grille material, the side walls being displaced slightly inwardly so that their free edge regions engage within the step 16. It will be observed in Fig. 2 that when the grille is located, a narrow portion of each side wall projects beyond the step, so that air can exit through these portions of the side walls, as well as through the front wall. Once the grille has been removed, a baffle plate may be retained on the inside of the grille (by means not shown), to enable a portion of the grille to be blanked off. For example, three quadrants may suitably be blanked off when the apparatus is to be placed near a corner of a room; or two quadrants may be blanked off when the apparatus is to be located in a ceiling, near a wall.In each case regions are blanked off in order to prevent air exiting the apparatus towards a wall or ceiling.

In use, the apparatus is located at the end of ducting of air conditioning apparatus, and forms the outlet into a room. It will normally be located in a ceiling. Air travelling along the ducting in the direction shown by the arrows A is deflected transversely.

By an induction effect, room air is drawn into the apparatus via the central region of the grille, as indicated by the arrows C. The room air and the fresh air mix within the unit and the mixture is expelled transversely, in a turbulent swirling manner, in the directions indicated by the arrows B.

Surprisingly, the grille 4 has not been found in preliminary tests to have any detrimental effect on the functioning of the apparatus, despite only 50% of the grille being free area, through which air can pass.

Indeed, preliminary tests have shown that the presence of the grille may have a beneficial effect on the functioning of the apparatus. A deflector unit of rectangular configuration may tend to give poor flow conditions from its corners. However, the apparatus as shown in the drawing appears to provide a more even flow distribution, around its entire periphery.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims (20)

1. Ventilation apparatus for use as a room outlet of an air flow pathway, in order to deflect air from a confined flow condition, along the pathway, to a dispersed condition, in the room, the apparatus comprising a deflector unit having a plurality of spaced deflector vanes arranged in a generally radial configuration about an axis, but inclined to that axis, thereby to discharge air in directions transverse to that axis, and a cover grille over the deflector unit, the cover grille having openings whose minimum width exceeds their depth.

2. Apparatus according to Claim 1, wherein the minimum width of the openings exceeds their depth by a factor of at least 4.

3. Apparatus according to Claim 1 or Claim 2, wherein the openings comprise at least 20% of the area of the grille.

4. Apparatus according to any preceding claim, wherein the openings constitute not more than 80% of the area of the grille.

5. Apparatus according to any preceding claim, wherein the grille is a plate with perforations.

6. Apparatus according to Claim 5, wherein the thickness of the plate is in the region 0.5 to 2.0 mm.

7. Apparatus according to any preceding claim, wherein the minimum width of the openings is in the range 1 mm to 20 mm.

8. Apparatus according to any preceding claim, wherein the openings are circular.

9. Apparatus according to any preceding claim, wherein the grille is detachable from the deflector unit.

10. Apparatus according to any preceding claim, wherein the grille and/or the deflector unit has means for locating baffle members therebetween, in order to alter the flow conditions.

11. Apparatus according to any preceding claim, wherein the grille is of stepped form, having a front wall and narrow side walls which include openings, such that when the grille is located over the deflector unit, the front wall is spaced from the outlet of the deflector unit and air may exit through the grille, via the openings in the side walls.

12. Apparatus according to any preceding claim, wherein the apparatus is arranged such that, in use, air exits from the apparatus in peripheral directions, generally transverse to the deflector unit.

13. Apparatus according to any preceding claim, wherein the apparatus is arranged such that, in use, room air is drawn into the apparatus, through a central region of the grille, by an induction effect.

14. Air conditioning apparatus comprising a ventilation apparatus according to any of Claims 1 to 13.

15. Apparatus according to Claim 14, wherein the apparatus serves as a room outlet located in a wall or ceiling of a room.

16. A cover grille for a ventilation apparatus, the cover grille having openings whose minimum width exceeds their depth.

17. A cover grille according to Claim 16, the cover grille having any feature of the cover grille described in any of Claims 1 to 13.

18. Ventilation apparatus substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.

19. Air conditioning apparatus substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.

20. A cover grille substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.