Abstract:
A V-type filter frame is disclosed for receiving a filter media pack. The V-type filter frame is arranged to be mounted to a filter bank grid and includes first and second gable plates and a front plate coupled thereto. The gable plates each include an abutment surface extending outwardly from an outer surface arranged to abut a filter bank grid when mounted thereto. A filter frame assembly and a method for assembling a filter bank are also disclosed.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to filter assemblies for removing particles from an air flow, and more particularly to a filter frame for receiving a media pack, a filter frame assembly, and a method of securing a filter frame assembly to a filter bank. 
       BACKGROUND OF THE INVENTION 
       [0002]    Filter assemblies comprising media packs disposed in a frame structure are known. A media pack is typically formed from a sheet of filter media, e.g. a fiberglass sheet, or a nonwoven polyester sheet or membrane media or combinations thereof or the like, which is pleated to increase the effective filtering area of the filter body, and provided with cover plates. To provide mechanical support and/or to combine a plurality of media packs, the media pack is typically arranged in a frame structure. 
         [0003]    A prior art filter frame for receiving several media packs is shown in U.S. Pat. No. 6,955,696, which discloses a filter frame comprising two gable plates, which have male connection elements, and two frame beams having female connection elements, which are interconnected with the male connection elements of the gable plates. Thereby a square frame is formed which supports the media packs. In other words, the media packs rest on the frame beams and on support structures of the gable plates. However, that structure requires a high rigidity of the two frame beams and a high stiffness of the media pack due to the small contact area with the frame. It would be desired to be able to mitigate these requirements. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present invention to provide a filter frame that eliminates, or at least reduces the drawbacks mentioned above. 
         [0005]    The object is achieved by a filter frame according to the present invention as defined in claim  1  of the appended claims. The object is also achieved by a filter frame assembly as defined in claim  13  and a method of assembling a filter bank as defined in claim  14  of the appended claims. 
         [0006]    Thus, in accordance with a first aspect of the present invention there is provided a V-type filter frame for receiving a filter media pack and arranged to be mounted to a filter bank grid. The V-type filter frame comprises first and second gable plates and a front plate which is coupled to the gable plates. The gable plates each comprises a front edge portion, located upstream an airflow, and an opposite rear edge portion, located downstream an airflow, and an inner surface, facing the inner clean side of the filter assembly, and an outer surface, facing the outer soiled side of the filter assembly. The gable plates further comprises an abutment surface extending outwardly from said outer surface. This abutment surface is arranged to abut a filter bank grid when mounted thereto. The provision of an abutment surface on the gable plate ensures that the forces acting on the filter frame, originating from the air flow through the filter media, can be transmitted by the gable plates directly to the filter bank grid. Many previously known filter frame assemblies are constructed such that the forces are transmitted from the filter media to the gable plates and then forwarded to a front plate and only then to the filter bank grid. That solution makes heavy demands on the adhesive coupling between the gable plates and the front plate which in a worst case scenario could break and in any case there is a immediate risk of air flow leakage between the gable plates and the front plate, which of course is inconvenient in a filter assembly. By directing the forces acting on the gable plate directly to the filter bank grid, as it is done by the present invention, this risk is minimized and the sealing properties of the front plate can be maintained at all times. 
         [0007]    In accordance with an embodiment of the V-type filter frame, the abutment surface is provided in the form of a flange extending along said outer surface. 
         [0008]    In accordance with an embodiment of the V-type filter frame, the abutment surface is provided in the form of a flange extending along at least one side edge of the gable plate. 
         [0009]    In accordance with an embodiment of the V-type filter frame, the gable plate has at least one V-shaped plate portion extending between a front edge portion and an opposite rear edge portion of the gable plate, with the mouth of the V shaped portion facing the front edge portion, said at least one V-shaped portion being defined by a channel arranged to receive a gable of a media pack. 
         [0010]    In accordance with an embodiment of the V-type filter frame, the front plate comprises a sealing surface arranged to abut a filter bank grid. The provision of a sealing surface on the front plate ensures optimal sealing properties between the filter bank grid and the filter frame. 
         [0011]    In accordance with an embodiment of the V-type filter frame, the sealing surface of the front plate is arranged to be substantially flush with the abutment surface of the gable plate. This means that while the gable plates will carry the main loads occurring during use of the filter assembly, the front plate will still carry a minor amount of the loads such that sealing between front plate and filter bank grid can be is ensured. 
         [0012]    In accordance with an embodiment of the V-type filter frame, a sealing member is provided at the sealing surface of the front plate. 
         [0013]    In accordance with an embodiment of the V-type filter frame, the sealing member comprises a compressible sealing strip. 
         [0014]    In accordance with an embodiment of the V-type filter frame, the sealing surface of the front plate is arranged outwardly adjacent the abutment surface of the gable plate. 
         [0015]    In accordance with an embodiment of the V-type filter frame, the front plate is coupled to the gable plates by means of a snap-lock element. A mechanical locking element such as a snap-lock will allow a person working with the mounting of the filter assembly to handle the frame assembly even before an adhesive has been supplied thereto. 
         [0016]    In accordance with an embodiment of the V-type filter frame, the front plate is coupled to the gable plates by means of an adhesive. The provision of an adhesive has a number of advantages. Among others, the adhesive provides excellent sealing properties such that no air can escape between the gable plates and the front plate. Further, it holds the gable plates and the front plate together. In combination with the snap-lock element, the mere presence of an adhesive in the space between gable plates and front platewill ensure that the snap-lock element cannot snap out of its locked position, thereby increasing the rigidity of the structure. 
         [0017]    In accordance with an embodiment of the V-type filter frame, a rear plate is engaged with rear edge portions of the first and second gable plates by means of a snap lock element. Similar to the use of snap-lock element between the front plate and gable plates, this makes the structure easier to handle during assembly. 
         [0018]    In accordance with second aspect of the present invention, a filter frame assembly comprising a filter frame as described herein and at least one media pack arranged in the filter frame is provided. 
         [0019]    In accordance with third aspect of the present invention, a method of assembling a filter bank is provided. The method comprises the following steps: 
         [0020]    providing a filter bank grid comprising at least one opening for a filter frame; 
         [0021]    providing a V-type filter frame comprising a front plate and first and second gable plates mounted to the front plate, wherein said gable plates comprises an abutment surface extending outwardly from an outer surface thereof and wherein the front plate comprises a sealing surface; 
         [0022]    providing a media pack in the filter frame; 
         [0023]    mounting said filter frame with media pack to the filter bank grid such that the abutment surface of the gable plates and the sealing surface of the front plate abut the filter bank grid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The invention will now be described in more detail and with reference to the appended drawings in which: 
           [0025]      FIG. 1   a  is a schematic exploded view of an embodiment of a filter assembly according to the invention; 
           [0026]      FIG. 1   b  is a perspective view of the filter assembly of  FIG. 1   a;    
           [0027]      FIGS. 2   a - 2   f  are schematic views of filter frame parts of the filter assembly. 
           [0028]      FIG. 3  is a schematic cross-section of filter frame parts according to the invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0029]    According to an embodiment of the filter assembly  100 , it comprises an embodiment of the filter frame  102 , and several, in this embodiment six, media packs  104  carried by the filter frame  102  whereby the media packs  104  have been shown separately in  FIG. 1   a  for reasons of clarity. The media packs  104  can be of any suitable kind, but typically each media pack  104  comprises a sheet of filter media  106 , which has been pleated to an accordion shape in order to increase the effective filtering area of the filter body, and backing nets  108  containing the pleated sheet of filter media  106 . Backing nets  108  are arranged to let air pass through the filter media  106 , or even arranged to guide the passing air in a preferred direction and optimized for low pressure drop thereover. 
         [0030]    The filter frame  102  comprises a front plate  110 , two gable plates  112 , and a rear plate  114 , embodied by three separate plate elements  116 . The front plate  110  is rectangular and comprises a peripherally extending rim  118 , and parallel ribs  120  extending between opposite ends  122 ,  124  of the front plate  110 . The front plate  110  has a groove  126  at each of the ends  122 ,  124 . Each groove  126  extends along a respective portion of the rim  118  at an inside thereof, and adjacent thereto. The gable plates  112  are arranged at the opposite ends  122 ,  124  of the front plate  110 . Each gable plate  112  has a front edge portion  128 , which has been received in the groove  126 . Each gable plate  112  extends perpendicular to the front plate  110 , and rearwards therefrom. The media packs  104  are plate shaped and extend obliquely substantially in the direction of the air flow from the front plate  110 , although they extend close to perpendicular to the front plate  110 . The media packs  104  are arranged side by side, leaning alternately to one side and to the other side, thereby forming a zigzag structure. More particularly, they are arranged in pairs, each pair forming a V shape, such that the mouth of the V shape faces the front plate  110 . A front edge  132  of each media pack  104  abuts against one of the ribs  120 , and apertures  130  between the ribs  120  are aligned with the mouths of the V shapes. Each gable plate  112  has three V-shaped portions  134  extending between the front edge portion  128  and an opposite rear edge portion  136  of the gable plate  112 , with the mouth of each V-shaped portion  134  facing the front edge portion  128 . The V-shaped portions  134  are joined along a minor fraction of their length, extending from the mouth towards the other end, while there are gaps between them along a major part of their length. Reinforcing elements  154  may be provided extending between two adjacent V-shaped portions to further increase the structural rigidity of the gable plate  112 . These reinforcing elements  154  can also serve as grips when handling the gable plates  112  or (semi-) assembled filter frame assemblies  100 . Each V-shaped portion  134  is defined by a channel, having side walls  138 . Each V-shaped channel has received gable portions, or side edge portions,  140  of two media packs  104 . Of course, it is also possible within the scope of the appended claims for the gable plates  112  to have additional or less than three V-shaped portions, such as one, two, four or more. Also, the gable plates  112  may not have V-shaped portions at all but may for example be provided in the form of covering having a trapezoid shape or similar without openings between adjacent pairs of media packs. Each plate element  116  of the rear plate  114  covers rear edge portions  142  of two media packs  104  forming a V-shape. The plate elements  116  each extend between, and are attached to, a respective fraction of the rear edge portion  136  of each gable plate  112 . Consequently, the front plate  110 , the gable plates  112 , and the rear plate  114  support each other to form a strong filter frame  102 , which carries the media packs  104 . 
         [0031]    An important part of the filter frame structure is the engagement between the gable plates  112  and the front plate  110 . As mentioned above, each one of the gable plates  112  has been received in a respective groove  126  of the front plate  110 . In order to secure a proper engagement between the front plate  110  and the gable plates  112 , each gable plate is provided with a retainment member  144 , and the front plate  110  is provided with a complementary retainment member  146  for each gable plate  112 . The retainment member  144  of each gable plate  112  comprises a snap-lock element  148  at either side of the gable  112 , and more particularly at each end of the front edge portion  128 , at a side edge  129 ,  131  of the gable plate  112 . The snap-lock element  148  comprises a resilient tongue  152 , which extends perpendicular or at an angle to a front edge of the gable plate, and which has a shoulder  156 . The complementary retainment member  146  comprises a recess  158 , which is arranged at the rim  118  of the front plate  110 . The shoulder  156  has been received in the recess  158 . Thereby the gable plate  112  is in fixed engagement with the front plate  110 . However, in order to further enhance the stability of the engagement, the retainment member  144  further comprises three protrusions  160 , which protrude from the front edge portion  128  perpendicular to the primary extension of the gable plate  112 . The protrusions  160  are distributed along the length of the front edge portion  128 . The complementary retainment member  146  further comprises three notches  162 , which are arranged at the rim  118  of the front plate  110 , one notch at each respective protrusion. The protrusions  160  have been received in the notches  162 . Each protrusion  160  is wedge-shaped, and each notch  162  is V-shaped. The sizes of the protrusions  160  and the notches  162  are such that they are connected to each other in a press fit when the gable plate  112  is inserted into engagement with the front plate  110 . The snap-lock elements  148  and the press fit connection between the protrusions  160  and notches  162  ensure a reliable coupling between the gable plates  112  and the front plate  110  even without the use of any adhesives such that the filter frame can be handled, e.g. lifted and moved around, without the need of any temporary securing means or similar. It should be noted that as regards the retainment member  144 , the number of protrusions  160  can range from zero to several, and the number of snap-lock elements  148  can range from zero to several as well. It is desired to have at least one snap-lock element or protrusion, and it is preferred to have two snap in elements with the shown placement and at least one protrusion. 
         [0032]    In  FIG. 3  it is shown that the gable plates  112  each comprises an abutment surface  184  near the front edge portion  128 . This abutment surface  184  is intended to bear against a filter bank grid  200 , made for example from steel beams, when mounted thereto. The front plate  110  is provided with a sealing surface  186  having a sealing member  188 , here in the form of a sealing strip made from polyurethane or similar. The sealing surface  186  is flush with the abutment surface  184  when the gable plates  112  are mounted to the front plate  110  such that both surfaces will bear against the filter bank grid when mounted thereto. It should be noted that in  FIG. 3 , for reasons of clarity, the abutment surface  184  of the gable plate  112  and sealing surface  186  of the front plate  110  is not yet in contact with the filter bank grid  200 . Instead,  FIG. 3  shows a position where the sealing member  188  barely touches the grid  200 . It is also possible, and sometimes preferable, to arrange the sealing surface  186  of the front plate  110  forwardly displaced relative the abutment surface  184 . If, for example, a thick and/or less compressible sealing member  188  is used, too much load may be transferred to the front plate  110  if the sealing surface  186  and abutment surface  184  are arranged flush with each other. By arranging the sealing surface  186  somewhat forwardly displaced relative the abutment surface  184 , the abutment surface  186  will reach the front surface of grid  200  earlier, thus not requiring excessive compression of the sealing member  188 . As will be described below, the filter frame assembly is to be fastened by means of clamps or similar that firmly squeeze the filter frame assembly against the filter bank grid  200 . When this is done the sealing member  188  will be compressed and the abutment surface  184  of the gable plate will bare against the filter bank grid  200  in a load absorbing manner. This results in that the forces originating from the air flowing through the filter media will be transmitted directly from the media pack  104  to the gable plates  112  and thereafter to the filter bank grid and only a minor part of these forces, if any at all, will be transmitted to the filter bank grid by the front plate  110 . This is favorable since the connection and sealing between the front plate  110  and gable plates  112  will not be exposed to any substantial stress thereby avoiding air leakage between them. The abutment surface  184  is here executed in the form of a flange running the whole width of a front part of an outer side of the gable plate  112  as well as on the side edges  129 ,  131 . This ensures uniform load transfer and good sealing properties between sealing surface  186  and the filter bank grid  200 . Other forms of execution of the flange are of course possible, for example in order to increase structural stability of the flange. 
         [0033]    The filter frame is assembled as follows. The front plate  110 , comprising the grooves  126  at the two opposite ends  122 ,  124  thereof is provided. The first and second gable plates  112  are provided and mounted at the front plate  110 . For each gable plate  112  the mounting includes inserting a front edge portion  128  of the gable plate  112  into a respective groove  126 , and forcing the retainment member  144  into engagement with the corresponding retainment member  146  of the front plate  110 . Thereby a part of the filter frame  102  which is ready to receive the media packs  104  has been assembled. In order to complete the assembling process to a complete filter assembly  100 , the next step thus is to mount the media packs  104  including backing nets  108 , and then the plate elements  116  of the rear plate  114  are mounted, wherein they are forced into engagement with the rear edge portions  136  such that snap-lock elements  192  of the gable plates  112  snaps into a locking position in the corresponding part in each rear plate  116 . As mentioned earlier, the filter assembly is now ready to be handled and could for example be transported to a different location without the necessity of any temporary securing means or similar. And then, in a last step of assembling the filter frame, an adhesive is used to seal and fixate the filter frame  102 . The mere presence of adhesive in the spaces between the different constructional details will prevent the snap-lock elements from leaving their locked position, which adds rigidity to the structure even before the adhesive has cured. Obviously, curing will further increase rigidity and stability of the structure by bonding the gable plates  112  and the front plate  110  together. Since the retainment member  144  will be glued into engagement with the corresponding retainment member  146  the snap-lock connection and press fit connection respectively will become even stronger. Other modes of mounting are obviously also possible, such as intermediate supply of adhesive. 
         [0034]    Thereafter, the filter frame assembly is inserted and secured to the filter bank grid  200 , typically the filter frame assembly is clamped to the filter bank grid  200  by means of a plastic or metal clamp which is fixed to the filter bank grid by means of a bolt and a fly nut or similar. Thereby, the filter frame assembly can be tightly squeezed between the clamp and the grid  200  without the use of through bolts or similar that would jeopardize tightness of the construction. When doing so, both the abutment surface  184  of the gable plate  112  and the sealing surface  186  of the front plate  110  are pressed against the filter bank grid  200  such that sealing is assured. When in use, the forces acting on the filter media  106  due to the air flow therethrough will be transmitted directly from the gable plates  112  to the filter bank grid  200  and no major forces will be transmitted from the gable plates  112  to the front plate  110  such that the sealing properties between the gable plates  112  and the front plate  110  can be maintained at all times. 
         [0035]    Finally, it is realized that the use of structure of the present invention with retainment members  144 ,  146  is a more user-oriented solution than known prior art constructions since it allows for a user to handle the frame assembly without the need of any temporary securing means or similar before the adhesive has been added and allowed to cure. Further, the provision of an abutment surface on the gable plate and a sealing surface on the front plate provides a construction with increased load bearing capacity while at same time improving sealing properties of the filter frame assembly. It should also be noted that the positions of the retainment member and the complimentary retainment member could be altered, e.g. the snap-lock could just as well be arranged on the front edge of the gable plate and the protrusion on the side edge of the gable plate and the corresponding goes for the complimentary parts of the front plate.