Abstract:
A filter fan includes a basic housing with a frame, wherein the frame is equipped with a quick fastening device in the form of spring-elastic clips. In order to prevent air and/or moisture from penetrating into a housing, the frame extends continuously and without openings around a circumference. The clips are molded onto the frame.

Description:
BACKGROUND OF THE APPLICATION 
     1. Field of the Invention 
     The present invention relates to a filter fan with a basic housing with a frame, wherein the frame is equipped with a quick fastening device in the form of spring-elastic clips. 
     2. Description of the Related Art 
     Filter fans are used to ventilate switch cabinets, electronic control devices and computers which are inserted into a corresponding opening in a housing wall, such as that of a switch cabinet. The filter fans have a blower in order to draw ambient air into the housing, wherein the housing is additionally equipped with air outlet slits. In order to prevent contamination of the electronic devices in the housing, the filter fan has a filter device, for example, a replaceable filter mat. 
     A filter fan of this type is known from EP 0 439 667 B1, wherein the filter fan has a basic housing with a frame. Quick fastening devices are provided on the frame in the form of spring-elastic clips, in order to insert the filter fan without additional screws or other mounting devices and without tools into a housing opening, and there to latch into place in the housing opening with the aid of the spring-elastic clips. 
     However, a disadvantage here is that the spring-elastic clips are cut out of the side walls or the frame of the basic housing of the filter fan, so that during operation of the filter fan, unfiltered air can be sucked in through these side openings into the interior of the housing, for example, a computer housing. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a filter fan of the type named in the introduction in which the intake of unfiltered air is avoided. 
     This object is attained, in accordance with the present invention, the frame extends continuously and without openings around its circumference and the clips are molded onto the frame. 
     With a filter fan designed in accordance with the invention, the quick fastening devices in the form of spring-elastic clips are not cut out of a section of a side wall or a frame of the basic housing of the filter fan, but are moulded onto the outer side of the frame, or on the side walls. Preferably, the filter fan or its basic housing consists of a plastic, injection-moulded part, so that when the frame is produced, the additional clips can already be moulded or formed on it as a single piece with the frame. Here, the clips are arranged virtually on the outer side on frame, and for example point outwards in a recess in a mounting wall when the filter fan is mounted. Furthermore, the frame is designed in such a manner that it extends continuously around the circumference of the filter fan, for example as a single component. 
     It is understood that the filter fan can additionally be equipped in the known manner with a filter mat and/or a blower and/or air guidance devices or the like. Naturally, slats which act as air guidance devices can also be constructed so that they can be pivoted. In principle, it is possible that only one single clip or several spring-elastic clips, preferably of the type described below, can be arranged on the frame. 
     The advantage of the invention is that due to the additional forming of spring-elastic clips on the frame of the filter fan, no further openings are present in the side outer walls, and the frame is essentially designed to run continuously and without openings around the circumference of the filter fan. As a result, unfiltered air is effectively prevented from penetrating, for example into a computer housing. Equally, no water can penetrate through the side walls into the interior of the filter, and a filter mat can therefore no longer become saturated with moisture. 
     The form of the filter fan can here be selected as required according to the invention; however, the filter fan is preferably rectangular, circular or oval. 
     The filter fan has essentially been described above in connection with switch cabinets, electronic control devices, computers or similar. However, it is possible to also use filter fans of this type in all other fields of technology, such as filter fans which are inserted into an opening of a construction site in order to ventilate an interior room of a building. In this case, the housing of the filter fan can be made of metal. 
     Particularly when mounting onto computer housing, switch cabinets or similar, the housing of which usually consists of thin-walled metal and/or plastic, it is recommended that a gap between an upper edge of a clip and a wall surface which forms a mounting wall contact edge which extends around be between one and four millimetres in size. In order to mount the filter fan, the basic housing is inserted into a prepared recess in the mounting wall, wherein the dimensions of the recess in the mounting wall correspond approximately to the outer dimensions of the frame of the basic housing. When the basic housing is inserted into the recess in the mounting wall, the spring-elastic clips are pressed down in the direction of the frame, or of its side walls. When the frame with its mounting wall contact edge has been brought into contact on the wall surface which borders the recess in the mounting wall, the spring-elastic clips spring back into their original position, and virtually lock the basic housing to the mounting wall. In order to release the filter fan, the spring-elastic clips can be pressed down with a suitable tool, such as a screwdriver, in order to be able to pull the basic housing back out of the recess. With the gap described above, the filter fan can, for example, be used on a thin-walled housing of a computer. 
     In order to position the spring-elastic clips, it is recommended that they be arranged on an upper and/or a lower side of a quadratic or rectangular filter fan, on one corner section in each case. In this way, the filter fan can for example be fastened to a housing in a simple manner with just two clips on the upper or lower side or with four clips on the upper or lower side. In principle, the clips can also be arranged on a right-hand side and a left-hand side of the filter fan. 
     Furthermore, the clips can be arranged on a right-hand side wall and/or a left-hand side wall of the filter fan, and in principle also on all four side walls. If only one clip is provided for each side wall of the housing, it should preferably be arranged in the center, in order to achieve symmetrical retaining forces. 
     For improved sealing of the filter fan inserted into a recess of the mounting wall, a sealing means is applied to the mounting wall contact edge in order to prevent air and/or moisture from penetrating between the mounting wall contact edge and a housing wall or mounting wall. In particular, the sealing means is designed in the form of a rubber seal made of a material which is suitable for this purpose, which is inserted into a groove which extends continuously around the mounting wall contact edge. The rubber seal can also be glued into place. 
     With regard to the form of the clips, it is recommended that they be triangular or rectangular. Here, the form, thickness and dimensions of the clips can be selected by persons familiar in the art depending on the quantity of the clips and their positions, as well as on the retaining forces required, i.e., essentially depending on the form and size of the filter fan. 
     In order to increase the ventilation performance, several filter fans with clips and frames constructed according to the invention can be inserted into an appropriately sized recess in the mounting wall. For this purpose, connection elements are provided which can in particular be latched together in each case with the clips of two adjacent filter fans, in order to attain a detachable connection between adjacent filter fans. Here, the connection element can be designed in any way required. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the drawing: 
         FIG. 1  is a vertical sectional view of a filter fan; 
         FIG. 2  is a view from the front onto the filter fan; 
         FIG. 3  is rear view of the filter fan with wing-type clips for quick fastening of the filter fan to a mounting wall; 
         FIG. 4  is a top view onto the frame of the filter fan with the wing-type clips; 
         FIG. 5  is an enlarged view of a section of the frame of the filter fan with a wing-type clip; 
         FIG. 6  is a further top view onto the frame of the filter fan with the wing-type clip; 
         FIG. 7  shows a filter fan in cross-section; and 
         FIG. 8  is a plan view of a filter fan. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The filter fan  100  shown in  FIGS. 1 to 3  includes a basic housing  10  with a blower carrier  101  which contains a blower  102  driven by an electric motor. The rear wall of the blower carrier  101 , which is open, is closed by means of a protective grid  106  ( FIG. 3 ). A frame  11  is preferably molded on the basic housing  10 . With a quadratic or rectangular filter fan  100 , the frame  11  consists of four side walls  14 ,  15 ,  20 ,  21  ( FIG. 8 ). 
     The basic housing  10  has on its front side a design support  103  with air guidance devices, for example in the form of slats  104  ( FIGS. 1 and 2 ). The design support  103  on the basic housing  10  holds a filter mat  105  for filtering the air which travels through the filter fan  100 . The filter fan  100  is made of one or more plastic injection moulded parts and/or of metal parts. The designed retainer  103  is preferably detachably connected with the basic housing  10  via a circumferentially extending seal  22 , in order to be able to replace the filter mat  105  ( FIG. 1 ). 
     When installed, the filter fan  100  with its basic housing  10  is arranged in a recess  23  in a mounting wall  24 , e.g. of a switch cabinet ( FIG. 1 ). 
     In order to fasten the filter fan  100  in a detachable manner in the recess  23  of the mounting wall  24 , the filter fan  100  is inserted into the recess  23  as shown by the arrow X ( FIG. 7 ). Here, the wing-type, spring-elastic clips  12  which are moulded on the frame  11 , as shown by the double arrow X 1 , can be slightly bent towards the center of the recess  23 . The clips  12  are preferably molded as a single piece with the side sections  14 ,  15 ,  20 ,  21  of the frame  11  ( FIGS. 3 ,  4 ,  5 ,  6  and  7 ). 
     As soon as the filter fan  100  has been pushed far enough into the recess  23 , the clips  12  spring back into their original position and lock the filter fan  100  into its inserted position. In order to remove the filter fan  100 , the clips  12  can be pressed gently back towards the inside. 
     In order to affix the filter fan  100  to a metal or plastic housing of, for example, a computer or a switch cabinet, the distance or gap  13  between an upper edge  25  of a clip  12  and a mounting wall contact edge of the basic housing  10  is preferably selected to be within a range of between one and four millimeters. 
     Here, the clips  12  can either be arranged in each case on a corner section  16 ,  17 ,  18 ,  19 , as shown on the frame  11  in  FIG. 8  on the top left-hand side, or in the center on a side wall  14 ,  15 ,  20 ,  21  as shown in  FIG. 8  on the lower right-hand side. The clips  12  can also be distributed freely as required on the frame  11 . The clips  12  can be formed in any way required, but are preferably triangular or rectangular. The clips  12  are not formed out of the wall material of the frame  11 , but are molded on ( FIG. 6 ), so that the side walls  14 ,  15 ,  20 ,  21  of the frame  11  form closed wall surfaces. 
     The number of clips  12  can be selected as required, as can their arrangement on the frame  11 . As well as arranging the clips  12  in the corner sections  16 ,  17 ,  18 ,  19 , clips  12  can also be provided in the central side wall sections of the frame  11 . At least two clips  12  should be provided on opposite side walls of the frame  11 . The clips  12  preferably are of the same material as the frame  11 , but the clips have a spring-elastic design as a result of which the clip  12  can spring back into place after the pressure applied to the clips is removed. 
     In order to seal the filter fan  100  when mounted, i.e. when the mounting wall contact edge or the basic housing  10  is essentially flush in contact with its surface on the mounting wall  24 , a rubber seal  22  which runs continuously around the filter fan  100  is provided. The seal  22  is made of a plastic material suitable for this purpose. In particular, the rubber seal  22  is glued into a groove in order to prevent air and/or moisture from entering between the filter fan  100  and the mounting wall  24 . 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.