Rotary drum air filter
This invention relates to air filters of the rotary drum type wherein air to be cleaned is moved into contact with and through the exterior surface of the rotary drum and then interiorly of the drum, and from where the air is typically recirculated in the plant or building. 
     In recent years it is become increasingly important to increase the filter capacity of a system in order to effect better cleaning of the air and to meet increasingly stringent government standards. With this in mind, it has brought to the forefront the need for a compact rotary filter with increased air filtering capacity. This invention provides such a compact filter with increased air filtering capacity by providing an increased surface area on the rotary drum by providing an undulating peripheral surface with peaks and valleys. This is accomplished by the rotary drum being formed of a plurality of side-by-side substantially circular filter media support members, which project radially outwardly from and are supported by an underlying cylindrical framework, and wherein each of the circular support members has opposing sloping sides arranged in radially outwardly converging relationship. Thus, filter media placed on such supporting surface serves for substantially increasing the surface area for filtration of the air. 
     It is an important feature of this invention to provide a rotary drum filter which is of modular construction. This modular construction utilizes a plurality of arcuate support segments adapted to be circularly arranged for forming the circular support members to thus facilitate forming the rotary drum filter of the desired size and length. 
     It is also a feature of this invention to provide in a rotary drum filter of the type described a suction cleaning device stationarily positioned and wherein a plurality of nozzles extend into the valleys of the rotary drum filter for effecting removal of the collected waste from the filter media on the drum. 
    
    
     Some of the objects and advantages of the invention having been stated, other objects and advantages will appear as the description proceeds, when taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a perspective view of the rotary drum filter assembly in a typical type of installation; 
     FIG. 2 is a fragmentary perspective view taken generally looking in the direction of arrow 2 of FIG. 1; 
     FIG. 3 is an enlarged fragmentary view of the drive arrangement for the rotary drum taken substantially along line 3--3 of FIG. 2; 
     FIG. 4 is a partially exploded perspective view of one-half of the rotary drum filter of FIG. 1 with the filter media removed from the surface thereof; 
     FIG. 5 is a cross-sectional view through the filter drum with the media removed; 
     FIG. 6 is another sectional view taken along line 6--6 of FIG. 5; 
     FIG. 7 is an enlarged partially exploded view taken along line 7--7 of FIG. 6; 
     FIG. 8 is a fragmentary view of the drive means alongside one end of the rotary filter drum; 
     FIG. 9 is a fragmentary view of one of the suction nozzles and illustrating the yieldable mounting arrangement thereof; 
     FIG. 10 is a partially exploded perspective view illustrating the manner in which the bands of pliable filter media are positioned in surrounding relation to the circular support members; and 
     FIG. 11 is a fragmentary view illustrating the manner in which the filter media may be secured by engaging circular bands in the valley portions of the drum. 
    
    
     Referring now to the drawings, reference numeral 10 broadly designates the air filter drum assembly which is illustrated as being supportingly mounted by a pair of end standards 11 and 11a. As illustrated, the standard 11a is positioned on the opposite side of a wall W from the other standard 11 so that one end of the filter drum extends through an opening in the wall. A suction fan F suitably provided adjacent the wall W serves for causing air to be moved into engagement with the surface of the rotary drum and through the interior thereof for effecting the desired filtration of the air. 
     For imparting rotation to the filter drum assembly 10, an internal ring gear 12 is provided on the open end of the filter drum as best seen in FIG. 2. A motive drive means 13 is suitably supported from end support 11a and has a pinion gear 14 cooperating with the ring gear 12 for imparting the desired rotation to the filter drum. As best seen in FIG. 8, a pivoted plate 15 suitably supports the motive means 13 so that the weight of the motive means 13 serves for yieldably maintaining the pinion gear 14 in contact with the ring gear 12. 
     Referring now particularly to FIGS. 4 and 6, the construction of filter media supporting modular units 21 is shown wherein each modular unit comprises a plurality of interconnected side-by-side arcuate support segments 22 each having sloping opposite sides arranged in radially outwardly converging relationship. As illustrated, each modular unit 21 has three arcuate support segments 22, with eight modular units shown being circularly arranged so as to collectively define a plurality of side-by-side substantially circular support members projecting radially outwardly. The modular units 21 are interconnected as by welding or the like. Each of the modular units 21 has the main portion thereof defined by perforated material such as screen wire 23, which has the inner and outer peripheral portions thereof secured by a surrounding framework 24, the framework 24 thus serving to provide the desired rigidity to the modular units. 
     To mountingly support each of the modular units 21 a skeletal framework 30 of generally cylindrical form is provided to which the modular units are secured. As shown, this cylindrical framework 30 broadly takes the form of a pair of spaced annular members 31 and 31a suitably interconnected with each other by a hollow shaft 32 and a plurality of radial spoke members 33 interconnecting the shaft 32 with the circular annular members 31, 31a. 
     Referring now to FIGS. 7 and 10 in particular, it will be noted that an annular band of filter media 40 is provided for covering the circular support members, the annular band having overlapping end portions 40a and 40b  desirably having attached thereto suitable strips 41 of Velcro material for effecting fastening of the overlapping end portions to each other. To further secure the filter media 40 on the circular support members, annular retaining bands 50 are provided for engaging the filter media in the valley portions thereof (FIG. 11). These retaining bands 50 are provided with suitable adjustment means 51 for effecting the desired tautness thereof. 
     In order to effectively clean the filter media 40, suction means is provided. As illustrated in FIG. 1, the suction means may take the form of a suitable blower 60 having a conduit 61 communicatively connecting a pair of manifold heads 62, each having a plurality of nozzles 63 carried thereby. The nozzles 63 are illustrated, are of tapered construction so as to be positioned within the valleys formed by the circular support members. Typically, the suction may be effective at all times, but may if desired be operable intermittently, dependent on the conditions of the air in the area that the rotary filter drum is to accommodate. 
     As illustrated in FIG. 9, the suction nozzles are yieldably mounted so as to move away from the filter media 40 in the event that an obstruction is present on the surface of the filter media. This yieldable mounting is accomplished by providing a hinge type mounting means 70 with the nozzles 63 being mounted on an upper component 71 thereof. A suitable stop 72 extends downwardly from the hinge component 71 to rest against a lower hinge component 73. As illustrated in dotted lines in FIG. 9, in the event an obstruction is encountered the nozzles 63 will move upwardly so as to permit the obstruction to move underneath the free end of the nozzles and thus permit the nozzles to thereafter quickly return to its original position. 
     For facilitating the side-by-side arrangement of a plurality of assembled modular units as noted earlier, each assembled circular modular unit has its own hollow shaft 32. As illustrated in FIG. 7, an internal coupling shaft 80 is provided with opposite ends being received within the confines of the hollow shaft 32 of adjacent assembled modular units and suitably connected therewith by cross pins 83. In a similar manner the ends of the assembled modular units are provided with coupling shafts 80a mounted for rotation in the upstanding brackets 11 and 11a. 
     It will thus be seen that there has been provided a rotary drum air filter wherein the filter drum is of modular construction to facilitate providing the desired size filter drum for accommodating the environmental conditions of the area to be served. 
     In the drawings and specification there has been set forth a preferred embodiment of the invention and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.