Abstract:
Air-conditioning device includes a holder which is to be arranged against the wall of the room and is provided with a top wall, front wall, side walls, base and rear wall. An opening for the supply of fresh air form the environment is arranged in the rear wall. An air-inlet opening for the air from the room is arranged in the base, while an air-outlet opening is arranged on the top side. The supply of fresh air and inlet opening emerge in a first chamber in which a fan is arranged. A HEPA filter is connected to this chamber. A control device is provided in order to control the ratio between the fresh air flowing in and the air from the room in question.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an air-conditioning device. 
     DESCRIPTION OF THE RELATED ART 
     Such an air-conditioning device is known from French patent publication 2,208,098. This document describes a device which takes up a very large amount of space and, moreover, has such a high weight that it has to be placed on the floor of a room. This device is intended not only for ventilation but also for the displacement of heat, i.e. for introducing heat or cold into the room in question. Consequently, it is necessary to arrange a radiator or the like therein. 
     Increasingly, society will no longer accept the noise and odour pollution resulting from ever increasing volumes of traffic. This means both road and air traffic. Regulations relating to acceptable sound levels inside houses are becoming increasingly strict, so that there is an ever increasing need to carry out sound-insulating measures. Although such measures are easy to carry out in technical terms, they present the problem of limited ventilation. 
     The authorities are defining ever more clearly the requirements which are to be satisfied by ventilation in a room, and if these requirements cannot be met, building permits and the like may be refused. 
     Hithereto, ventilation has been achieved with the aid of sound-proofing boxes. The use of ventilators and other mechanical air-displacement means allows optimum ventilation to be ensured under all conditions. However, this entails large devices as described in French patent 2,208,098. Other examples of particularly complex, large devices of this nature are to be found in American patent 5,225,176 and PCT application WO 95/30862. 
     Particularly when retrofitting additional ventilation features after a room has been sound-insulated, it is impossible to use the devices shown in these publications, for their bulk is such that their installation requires major alterations, which will not be acceptable to existing residents. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide an air-conditioning device which can be of compact design and which does not entail any significant further increase in noise in the room in question. Moreover, it is important for a device of this nature to filter out harmful or undesirable substances as far as possible, while it is also intended that it should be possible to retrofit such a device in residences, offices and the like. Moreover, it is important that the mechanical displacement of air should take place as efficiently as possible, so that the device itself can be as efficient as possible. 
     Moreover, it is also sought to provide optimum filtering, i.e. to be able to filter out even very fine particles, such as soot particles. 
     This object is achieved in an air-conditioning device as described above, by means of the characterizing features of claim  1 . 
     The arrangement of the invention allows a particularly compact design. Installing the mechanical air-displacement means, such as ventilators, makes it possible to overcome a relatively great pressure difference across the filter, i.e. a relatively dense filter can be used, making it possible to filter out even small particles, such as soot particles. Moreover, it has been found that the arrangement according to the invention produces particularly little noise while allowing particularly compact external dimensions. A level of approximately 25 dba for the filter is given as a non-limiting example. 
     Arranging the inlet opening in the base, in contrast to the device described in French patent 2,208,098, results in a more natural ventilation and makes it possible to limit the sound pressure further. 
     In a preferred embodiment, the control means may comprise mechanical control means, such as a flap assembly. This flap assembly controls the effective cross section of the inlet opening and of the opening for fresh air. Preferably, the flap assembly is designed in such a manner that the total cross-sectional area, through which air flows, of these two openings remains essentially the same in each position. Moreover, it is possible to provide the mechanical air-displacement means, such as a ventilator, with an electronic control unit, which makes it possible to control the flow rate through the air-conditioning device according to the invention. 
     According to a further variant of the invention, further mechanical air-displacement means are present. 
     By influencing the flow rate brought about by the two mechanical air-displacement means both in the absolute sense and with respect to one another, it is possible to provide very accurate control which is optimally adapted to the prevailing conditions, with the result that an optimally low power consumption is obtained. 
     This power consumption can be limited still further by designing at least one of the said air-displacement means as ventilators which are provided with DC motors. 
     According to a further advantageous embodiment of the invention, the outlet opening is arranged in a top surface which lies at a short distance below the free ends of its delimiting side, front and rear walls. The result is a further reduction in the sound pressure. Moreover, it has proven advantageous to arrange the mechanical air-displacement means for the inlet-outlet opening path as close as possible to the outlet opening and as far as possible from the inlet opening. The device according to the present invention can be retrofitted particularly advantageously in residences and will preferably be arranged at a reasonable height, in order, as far as possible, to avoid draught. The compact device according to the present invention allows this to take place in a simple manner. 
     Access to the filter, which will have to be cleaned periodically, is simple if the front wall of the holder is arranged so as to be at least partially removable. The filter may comprise any material which is known in the prior art. This filter may also comprise a combination of different layers. An example which may be mentioned is a so-called HEPA filter combined with a layer of activated carbon material. A filter of this nature may be arranged so that it is folded up inside the housing in question. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail below with reference to exemplary embodiment which are depicted in the drawings, in which: 
     FIG. 1 shows a partially cut away, perspective view of the air-conditioning device according to the invention; 
     FIG. 2 shows a side view, in cross section, of the device in accordance with FIG. 1; 
     FIG. 3 shows a cut away perspective view of a further variant of the air-conditioning device according to the invention; 
     FIG.  4 . shows a side view, in cross section, of the device in accordance with FIG. 3; and 
     FIG. 5 shows a detail of the device in accordance with FIGS. 3 and 4 which provides further details of the control means. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The air-conditioning device according to the invention is denoted overall by  1  in FIGS. 1 and 2. It is attached to wall  2  of a room by means of attachment means, which are not shown in more detail. This wall is the outside wall, and a hole  3  for supplying fresh air via the feed opening  9  for fresh air, which is arranged in the rear wall  23  of device  1 , runs through this wall. 
     The device moreover comprises two opposite side walls  4  and a top wall  5  and base  6 . A removable cover  13  is arranged on the front side. An inlet opening  7  is arranged in base  6 , while top wall  5  is at a lower level than the top edge of rear wall  23 , side walls  4  and cover  13 , which edge is denoted by  25 . Between inlet opening  7  and outlet opening  8 , there is, firstly, a filter  10  and, then, a ventilator comprising a blade wheel  14  and a DC motor  15 . The DC motors which are used here make it possible to improve the efficiency by at least 50% by comparison with the AC motors which are known in the prior art. Moreover, such motors, for example 24-volt motors, are very easy to control and the efficiency does not decline drastically in the relatively low load range. It has been found that optimum ventilation can be obtained at a very log power level. A power level of between, for example, 6 and 40 watts has been found to be a realistic level for each of the ventilators. In the vicinity of inlet opening  7 , a further ventilator, comprising a blade wheel  16  and a motor  17 , is arranged in feed opening  9  for fresh air. This latter ventilator is arranged in first chamber  11 , while the ventilator comprising the components  14  and  15  is positioned in a second chamber  12 . 
     A coarse filter which prevents moisture and coarse contaminating substances from the environment from entering may be arranged in feed opening  9 . Moreover, the ventilator which is connected to said feed opening may be arranged sideways in the box. 
     The various walls may be lined with a sound-proofing material, such as a blister padding  24 . 
     A control unit  18  is arranged on one of the side walls, which control unit, on the one hand, is connected to each of the ventilators, and, on the other hand, is provided with a control panel  19  and is also provided with a mains power supply, which is diagrammatically denoted by  20 . 
     The filter described above is a folded filter structure on which a panel of activated carbon  22  is arranged. The folded filter structure comprises a filter layer of impregnated HEPA material  21 , between which a further layer  30  of activated carbon is arranged. A filter of this nature is able to filter both larger dust particles (larger than approximately 2.5 μm) and very fine dust particles(smaller than 0.3 μm). It has been found that smaller dust particles, in particular, may be very harmful to health. 
     This filter assembly is designed as a cartridge, so that it is easy to replace. 
     A grate which is formed inductively and has sound-proofing properties may be arranged both downstream of the ventilator  14 ,  15  and in the inlet opening  7 . 
     EXAMPLE 
     A height of approximately 40 cm, a depth of approximately 13 cm and a width of approximately 22 cm may be mentioned as possible dimensions for the air-conditioning device shown here. Such dimensions make it possible to achieve a circulation flow rate of approximately 150 m 3 /h and a ventilation flow rate of 75 m 3 /h, which according to Dutch standards is sufficient to provide optimum ventilation for a room of approximately 15 m 2 . 
     It has been found that the use of DC motors and controlled operation of these motors using control unit  18  make it possible to achieve a very low power consumption combined with optimum ventilation. It is even possible to operate motor  16  so as to pump air out of the room under stormy or other exceptional weather conditions. By varying the action of the various ventilators with respect to one another, it is always possible to provide optimum adaptation to the prevailing conditions. Control panel  19  may comprise a number of buttons, but it is also possible for it to be provided with a (light−) sensitive cell which is influenced by a remote control unit (not shown in more detail). It is possible to programme the device in such a manner that it is operated according to a number of fixed programmes, so that the user cannot completely disrupt the device. 
     By arranging the inlet and outlet openings essentially in the horizontal plane, on the one hand draught is as far as possible prevented and, on the other hand, the sound pressure is limited as far as possible. An inlet opening which lies in the vertical plane, as is customary in the prior art, will entail a higher noise level. 
     Apart from the filter which is shown here, further filters may be present. Consideration may be given, in particular, to a filter in feed opening  9 . 
     It will be understood that FIGS. 1 and 2 merely show an exemplary embodiment of the invention and that numerous variants are possible. Thus it is possible, for example, to use a radial arrangement instead of the axial blade wheel  14  which is shown. The same applies to blade wheel  16 . 
     FIGS. 3-5 show a variant of the air-conditioning device according to the invention. This device is denoted overall by  31  and is designed to be arranged against a wall  32 . In this wall  32 , which delimits a room or the like from the environment, there is a hole  33  for supplying fresh air via the feed opening  39 , which is arranged in the rear wall  53  of the device  31 . 
     The device moreover comprises two walls  34  which lie opposite one another and a top wall  35  and base  36 . A removable cover  43  is arranged on the front side. An inlet opening  37  is arranged in the base  36 , while the top wall  35  is provided with an outlet opening  38 . A filter  40  is arranged between the inlet opening  37  and outlet opening  38 . A buffer chamber  42  is delimited beneath this filter  40 . This buffer chamber  42  opens out at the outlet of a ventilator housing  44 . A ventilator motor  45 , which may comprise the DC motor  15  described above, is arranged in this ventilator housing. A blade wheel  46  is backwardly curved is also provided. The rotational speed of the blade wheel  46  is set by means of a control unit  48 . A power supply cable is denoted by  50 . 
     Part of the ventilator housing  44  projects into first chamber  41 . This chamber is provided with a sound-insulating lining  45 . Moreover, an inlet opening  37  which is arranged in base  36  and a feed opening  39  for fresh air, as described above, open out into the first chamber  41 . The inlet opening  37  for fresh air may be closed off with the aid of tilting flap  55 . The feed opening  39  for fresh air is controlled with the aid of two slide plates  68 ,  69  each provided with an opening  70 . These slide plates are able to move with respect to one another. The maximum diameter is established if the openings  70  lie one above the other, and as the openings move away from one another the size of the opening will become increasingly smaller but will continue to lie in the centre, so that the increase in noise is limited as far as possible. 
     In addition to a control button for control unit  48 , the device in accordance with FIGS. 3-5 is provided with a control button  60 . In the present case, this button is present on two sides and is connected by means of a rigid rod  59  which is connected to both buttons. Pins  61 ,  62  are present, in different angular positions, on each of the control buttons  60 . Pin  61  engages in the cam track  71  of a slide plate  58 . This slide plate  58  is provided with a central slot for accommodating rod  59 . By rotating button  60 , slide  58  is moved to and for by the engagement between slot  71  and pin  61 . As a result, via connection  57 , tilting flap  55 , which is arranged pivotably, is actuated at pivot  56 . 
     Slide  63  is moved to and for in a corresponding manner by the action of pin  62  in cam track  72 . Connection  64  is coupled to rocker arm  65 , which by means of a pin is pivotably connected to a fixed part of the housing. This rocker arm moves pins  66  and  67  in opposite directions. Pin  66  is connected to slide  69 , while pin  67  is connected to slide  68 . 
     The shape of the cam track  71 ,  72  and the position of the pins  61 ,  62  is selected to be such that the control ensures that the total area of flow of the inlet opening  37  and the feed opening  39  for fresh air remains essentially constant. As a result, it is possible, depending on the conditions, to supply exclusively fresh air or, for example in the event of disasters, to shut off the system entirely from the outside world. In both cases, and also in all other intermediate cases, the flow resistance to which the ventilator is subject is equal and the noise performance can be optimized. 
     Using a backwardly curved blade wheel makes it possible to design the outlet of the ventilator housing  44  so as to extend across the entire width of the housing, so that the air speed is limited and the noise pollution is reduced in this way. In the embodiment in accordance with FIGS. 3-5, it is also preferred to use an HEPA filter, and more particularly in accordance with standard EU 9/10. 
     The above text merely describes two embodiments of the present invention. It will be understood by the person skilled in the art that numerous further variant are possible without departing from the scope of the present application.