Such air distributors or air spreaders are used in air treatment apparatuses and their purpose is to distribute the air downstreams of a fan outlet as evenly as possible, which will improve the utilization of the following functions of e. g. a cooling battery, a filter or a silencer.

In air treatment apparatuses very often centrifugal blowers are used, which have rearwardly bent blades due to their satisfactory performance in the form of a high efficiency and the possibility of using a high pressure. However, the speed profile directly downstreams of the outlet of the fan is very uneven and has a high maximal level. Due to this disadvantage it is fundamentally always necessary to use some form of balancing of the speed profile, before the air stream reaches the following functional units. Only in those instances, when the fan outlet leads directly into a straight duct, it is possible to not take the speed profile into consideration.

Certain functional units are particularly sensitive to an uneven speed profile along their front surface, i. e. cooling batteries, silencers, air dampers and filters. Also, as regards recovery units, i. e. rotating heat exchangers and fluid coupling batteries, great caution must be exercised. An uneven speed profile along the front surface of the respective functional unit means i. a. , that the pressure drop increases. This increase affects of course to the largest extent those functions, which normally have a large pressure drop for an even speed profile, i. e. cooling batteries, recovery units and certain types of filters. As regards cooling batteries that serious drawback is added, that the heat transfer will be severely impaired in certain parts of the

battery, which leads to lower cooling efficiency. Also, the risk of splash from the battery surface increases in those cases, when the battery is used in a wet environment. As regards silencers, the uneven speed profile and also the pressure drop increase expose certain parts of the open surface of the silencer to such a high air speed, that the inherent noise creation more or less eliminates the expected silencing. Filters, which are exposed to an uneven air speed, may also be damaged just because of mechanical reasons and hence loose the filtering characteristics entirely or partially.

In order to distribute the air downstreams of the fan outlet the presently used solution is to place a plane perforated plate in front of the outlet. The perforated plate is mounted on supports, which are fastened to the gable side of the apparatus at a distance, which varies depending on the size of the fan from about 200-400 mm. The mounting and the dismounting of such an air distributor are tedious, time consuming and expensive. The used fastening means may be undone due to vibrations, which also may cause noise creation. Depending on the perforation degree of the plate, the plate will provide a larger or smaller resistance to the air to pass in a straight direction through the plate. The resistance results in, that a portion of the air flow is angled with about 90° and escapes outwards through the open sides. It is true, that the plate subdivides the large axial air stream into partial streams, but all of them also have mainly axial directions and cannot cause any satisfactory distribution pattern. Another problem with such a solution is, that it is difficult to optimize the pressure drop across the plate and simultaneously keep the construction variations at a reasonable level. In order to obtain a reasonably acceptable speed balancing within a reasonable pressure drop area, it is necessary, for each fan size and apparatus size respectively, to construct an individually shaped distributor plate.

The present invention relates to an air distribution, which is directly connected to a fan outlet. The speed profile in the outlet is very uneven and the typical maximal speed is 12-20 m/s. The air stream is completely turbulent. The purpose of the air distributor is to distribute the flow evenly across the cross section of the adjacent functional unit. This cross section has a much larger cross-sectional area than the outlet from the fan. The speed reduction compared to the maximal speed is typically 3-4-fold. The air flow downstreams of the distributor is still turbulent.

The object is not to obtain a laminar flow. It is important for the usefulness of the air distributor, that the distribution is obtained with the least possible pressure drop. An acceptable loss is 30-60 Pa. The air distributor according to the invention must per se be able to stand possible mechanical forces, as regards its fastening and the materials used.

DE 3605539 describes an apparatus designed to introduce an air flow to a room, which apparatus comprises a plate, provided with a hole pattern and fastened in a frame all around, one side of the plate being covered by a fabric, which is fastened to the edge of the plate all around. The purpose of this construction is to unload the fabric with reversing air blows, the fabric being pressed against the plate without being damaged.

Regardless of the design of the hole pattern in the load receiving plate and the fabric respectively, a distribution can only take place within its own surface area.

The distribution of the air flow outwards into the following cross section of the apparatus will be very marginal. By placing the perforated plate in the hole in addition an unreasonably high press drop is obtained, which also means, that the performance of the fan in the form of efficiency and available pressure increase more or less will be lost.

The object of the present invention is to, to a great degree counteract and eliminate respectively these drawbacks and provide a generally advantageous air treatment apparatus, which develops the state of the art, in the functional field as well as other fields, e. g. relating to accident prevention, quick mounting and dismounting as well as exchanges.

These objects are attained according to the present invention by designing an air treatment apparatus of the type described in the introduction, mainly in such a way, as is set forth in the characterizing clause of claim 1. Thanks to the invention i. a. a radial distribution of the air, which escapes through the air distributor, is obtained in connection with the air distributor and consequently also a substantially better distribution pattern than before.

Additional characteristics and advantages of the invention are set forth in the following description, reference being made to the accompanying drawings, which show a few preferred but not limiting embodiments of the invention and in which: Fig 1 is a perspective view from above of an air treatment apparatus with an air distributor according to the invention in its resting position; Fig. 2 a corresponding view of the same apparatus with its air distributor not fully active; Fig. 3 a corresponding view of the same apparatus with its air distributor fully active; Fig. 4 a perspective view of an air distributor according to the invention with fastening means attached to the apparatus; and Fig. 5 a view of a modified air distributor according to the invention.

In the drawings an air treatment apparatus 1 is shown in its entirety. The apparatus usually has a parallelepipedic shape and is constructed according to a variable module system. In the shown embodiment a frame 2, which extends around the

edges of the apparatus, leaves one outer gable 3 completely open and to be connected to a refrigerating machine, a heat exchanger or the like (not shown).

Inside open gable 3 there is a space 4 having a certain depth, e. g. 0. 5-1 m, in the longitudinal direction of the apparatus. The purpose of the space is to provide an area for mounting an air distributor and to obtain a certain distance to said connectable parts in order to equilibrate the air stream. Space 4 is accessible from the side through a door or lid 5. The following sections, only shown from the outside, are provided: a fan section 6, an inspection section 7 with a door or a lid and an inlet section 8, to which an additional part 9, e. g. a filter, can be connected.

A side 10 of fan section 6 can be seen through gable 3. This side preferably is centrically provided with a rectangular fan outlet 11, through which the fan air stream is fed. This outlet is according to the invention provided with a thin, flexible air distributor 12 in the form of a rectangular fabric, a sheet or the like.

This distributor suitably is fastened, with its upper and lower edges 13 and 14 respectively, to upper and lower respectively edges 15 and 16 respectively of the fan outlet, whereas the side edges of the distributor are loose and not fastened to side 10. Between the fastening edges at the fan outlet the distributor is substantially longer than the fan outlet in the same direction, e. g. 10-50 %, preferably 20 %.

However, the distributor suitably has roughly the same width as the fan outlet, in some cases e. g. 5-20 % wider than the fan outlet.

The distributor suitably is made of a coated polyester fabric and is provided with holes 17, preferably arranged in a regular pattern, particularly circular and/or oval or rectangular oblong holes with arc-shaped ends. Within or outside the frame of a regular pattern the size, the number and/or the shape of the holes can vary, e. g. with larger and/or more holes in a direction towards the edge areas, particularly the fastening edge areas. The total hole surface can be 10-70 %, preferably about 40 %, of the entire surface of the distributor.

The preferred fastening method, shown in Fig. 4, for a distributor according to the invention comprises a fastening bracket or the like 18, which with one leg and the two legs 19 and 20 respectively e. g. is riveted or screwed into the material, which surrounds fan outlet 11. From the ends of the leg, which abut side 10 in a planar direction, bearing eyes 21 project in a perpendicular direction, in bearing holes 22 of which a through fastening rod 23 is mounted, the insertion position of which is secured by means of spring pins 27, which outside the bearing eyes are to be inserted into holes and grooves in the rod ends. Within the area of the rods the distributor is folded twice and end 24, folded backwards, is fastened to the distributor by means of a weld seam or the like 25, In this manner a very quick mounting and dismounting of a distributor is possible, since the rod simply only has to be inserted through the eye, obtained in this way, and the joining be secured by means of the spring pins. This joining is also excellent, since minimal operating stresses will be obtained and also an acceptable revolving capability around the rods and consequently an unlimited adaptability to various operating positions as well as a maximal life.

In Fig. 1 the apparatus and consequently also the air distributor is shown in an idle position. The distributor is then loosely suspended, surplus material being shaped into a soft enclosure. If space 4 is to be inspected, the distributor does not constitute a risk for the operators or the door as far as collision is concerned.

Thus, the maximally opened door might strike and push aside parts of the distributor without any damage. In this way a larger flexibility is obtained, when air treatment apparatuses in this technical field are constructed, particularly when it is considered necessary or suitable to use doors to be opened inwards, due to the overpressure in space 4. This means in practice, that the length of the apparatus can be shortened by 200-400 mm.

When the fan is started or a heavier air distribution fabric is chosen, e. g. with attached or inserted weights, in combination with a weaker fan, a bending outwards of the fabric is obtained in the form of half a heart, turned upside-down, in the cross section of the fabric (Fig. 2). Then the main portion of the air stream flowing through the fabric is directed forwards and somewhat upwards, whereas a smaller portion is directed downwards. The air escapes through the open sides mainly without hindrance, which is indicated by arrows 26. In case the chosen air distributor embodiment according to Fig. 2 is chosen for the main operation, this may also have en effect on the location of outlet 11, which consequently may be given a lower position than otherwise.

When the fan is run with full capacity and a lighter air distribution fabric is chosen in combination with a stronger fan (see Fig. 3) respectively, the cross section of the distribution fabric will be arc-shaped and the partial streams, which escape through the fabric will be directed radially outwards more evenly, side streams 26 simultaneously also in this case escaping without hindrance. In connection with a design or a phase according to Fig. 2 as well as ditto according to Fig. 3 the distributor according to the invention is self-adjusting between a minimal and a maximal pressure usage.

Thanks to the specific characteristics of such an air distributor according to the invention the pressure used by the fan can be used to provide an optimal form of air distribution having an air direction in the perpendicular direction along the entire length of the fan. When the fan is stopped, also that advantage is obtained, that the fan outlet is shut off, because the distributor fabric covers fan outlet 11, which enhances the security against an unintentional contact with the impeller, positioned behind the distribution fabric.

The invention is not limited to the embodiments, described above and shown in the accompanying drawings, which only are to be considered to be exemplifying and which can be modified and supplemented in an arbitrary way within the scope of the inventive idea and according to the enclosed claims. Thus, the air distributor can completely or partly be manufactured with a fabric, a net or the like, which is permeable per se. Also, the fabric can be subdivided into strips between its fastening areas, openings being obtained through the spaces between adjacent strips. Also, it is possible to fasten the fabric at vertical edges of the outlet opening, larger amounts of air being able to escape upwards and downwards without hindrance. Also, it is possible to provide the fabric with several, eyes arranged after each other, such a fabric being able to obtain different bending radii when fully loaded. Alternatively, two rods can be vertically mounted, e. g. at the lower outlet edge, and a plurality of mounting eyes above each other, and in this case the fabric will be placed behind the upper rod and be pulled with en eye onto the lower rod, which can be introduced into mounting eyes at one or several alternative levels. Also, in this way various bending radii and consequently various air distribution patterns can be obtained.