Patent Publication Number: US-8523970-B2

Title: Portable air filter

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention is directed toward a portable air filter. The invention is further directed toward a portable filter unit including the air filter. The invention is also directed toward a carriage for the air filter. 
     2. Background Art 
     Portable, on-ground, air filters that take in air to be filtered through a wall of a cylindrical filter, and eject the filtered air from an open end of the cylindrical filter, or an outlet portion in the cylindrical wall of the filter, are well known. Such filters are not however well adapted for filtering air in active workplaces where there is a lot of dust and debris in the air, particularly where the dust and debris in the air is localized in the workplace. The known filters are not readily or easily portable so they can be easily located where the worst air conditions are located in the workplace and/or easily repositioned when the location of the worst air conditions change. The known filters are also not equipped with means to easily distribute the filtered air where needed. They are further not equipped to easily collect the air from specific areas in need of filtering. 
     SUMMARY OF THE INVENTION 
     It is the purpose of the present invention to provide a portable air filter that can be easily moved and repositioned when needed. It is another purpose of the present invention to provide an air filter that can be adapted to move air through the air filter in either direction. It is another purpose of the present invention to provide an air filter unit, including the air filter, that can easily distribute the filtered air where needed or collect the air to be filtered from a specific work area. It is a further purpose of the present invention to provide an air filter unit that can be used without a filter to move air some distance to or from the filter unit as required. It is a further purpose of the present invention to provide an air filter unit that includes a carriage for the air filter that is adjustable to be able to mount the air filter in various positions depending on its location and use. It is another purpose of the present invention to provide an air filter unit that has an efficient collector hood for collecting air from a work area. It is still another purpose of the present invention to provide a carriage for an air filter. 
     In accordance with the present invention, the air filter of the present invention has a rigid, perforated, shell having an open end and a closed end with a blower unit connected to the open end. The blower unit is preferably detachably connected to the shell. The shell is preferably cylindrical in shape. The blower unit has a through duct with an inlet end and an outlet end. There is an impellor in the duct and a motor to rotate the impellor. A Hepa filter is mounted inside, and adjacent, the shell. In normal use, the fan pulls air through the perforated shell and the Hepa filter into the interior space of the Hepa filter to clean the air and then directs it from the interior space into the inlet of the duct and out the duct outlet. 
     The air filter forms part of an air filter unit. The filter unit can include elongate, flexible, tubing which can be detachably connected to the duct outlet in the blower unit. Connecting means are provided on the blower unit and on the ends of the tubing for connecting the tubing to the blower unit. The tubing can be a single length of tube or several tubes serially connected together. A second blower unit can be provided for connection to the free end of the tubing or for connection between adjacent tubes if needed to efficiently move the air. The air filter unit, with the tubing, is primarily used to filter the air in a work area, normally passing the air through the shell, and its filter, into its interior, out the blower unit, and through the tubing back to the work area. The filter unit can also be used in reverse to collect and pass air from a work area through the tubing, the blower unit on the air filter, the filter, and the shell. The filter could be omitted when passing air in either direction and then the filter unit is used to just move air efficiently in either direction without filtering it. When collecting air from a localized work area using the tubing, the unit could be provided with a collecting hood having an enlarged inlet and a smaller outlet connected to one end of the tubing. 
     The air filter unit includes a carriage for carrying the air filter. The carriage has a frame with a bottom support and a top support for receiving the air filter. The carriage has wheels on the bottom support and a handle on the top support by means of which the carriage, with the air filter thereon, can be moved. The carriage has a leg means and short intermediate support means. The leg means can be used to support the frame, and carried air filter, by the wheels and the leg means at an angle to the ground. The frame can also be supported on its bottom support with the frame, and air filter, upright. And the frame, with the air filter, can be horizontal on the ground supported at its front end by the short intermediate support and the wheels. 
     The invention is particularly directed toward an air filter, the air filter having a shell, the shell comprising a perforated, tubular wall, a first end wall at one end of the tubular wall closing the one end, and a second end wall at the other end of the tubular wall having an opening. A tubular Hepa filter is removably mounted within the shell adjacent the perforated wall. The air filter has a blower unit having a through duct, the duct having duct openings at its two ends, a fan in the duct, and a motor for rotating the fan. The blower unit is mounted, preferably detachably, on the second end wall with the duct passing through the opening in the second end wall to have the one duct opening inside the filter whereby rotation of the fan moves air from outside the air filter through the air filter between the perforated wall and the duct, the air passing through the filter. 
     The invention is further directed toward an air filter unit employing the air filter and flexible tubing connectable to the other duct opening to direct air to or from the air filter to a desired location. 
     The invention is also directed toward a carriage for supporting the air filter on the carriage, the carriage having means allowing the carriage, and the carried air filter, to be positioned in one of several different positions as may be needed in the work area and for transporting the air filter to and from the work area and also about the work area as may be needed when using the air filter. The carriage preferably forms part of the filter unit. 
    
    
     
       DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side view, partially cut-away, of the filter unit. Comprising the air filter and the carriage, in an upright position on the ground; 
         FIG. 2  is a side view of the filter unit at an angled position on the ground; 
         FIG. 3  is a partial cross-sectional view of the upper part of the air filter taken along line  3 - 3  in  FIG. 1 ; 
         FIG. 4  is an enlarged view of detail ‘A’ in  FIG. 3 ; 
         FIG. 5  is a partial cross section view, similar to  FIG. 4  of another embodiment of the invention. 
         FIG. 6  is a schematic view showing part of the filter unit with a flexible duct and a wand; 
         FIG. 7  is a schematic view showing part of the filter unit with a second blower unit; 
         FIG. 8  is a schematic view showing part of the filter unit with branch lines; 
         FIG. 9  is a side view, in partial cross-section showing part of the filter unit with a collector hood; and 
         FIG. 10  is a schematic view showing a number of units arrange in an air capture cleaning configuration. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The filter unit  1  of the present invention, as shown in  FIGS. 1-4 , has an air filter  3  with a rigid, shell  5 . The shell  5  is preferably cylindrical in shape, as shown, although other shapes could be used. The shell  5  has a tubular wall  6  defining with perforations  7 . One end of the wall  6  is closed with an end wall  8 . The other end of the shell  6  has an end wall  9  with a central opening  11  therein. 
     The air filter  3  includes a blower unit  13  that is mounted to the shell  5  adjacent its end wall  9 . The blower unit  13  has a through duct  15  with duct openings  17 ,  19  at the ends of the duct. Duct opening  17  is normally the inlet to the duct  15  and duct opening  19  is normally the outlet from the duct  15 . A fan  20 , and an electric motor  21  for rotating the fan  21 , are mounted in the duct  15 . The duct  15  can have a collar  22  with end walls  23 ,  24  near the duct openings  17 ,  19 . The blower unit  13  is preferably detachably mounted on the other, open end of the shell  5  with the duct  15  passing through the opening  11  in the end wall  9  of the shell  5  to locate the inlet duct opening  17  within the shell  5 . The end wall  23  of the collar  22  on the duct  15  sits on the end wall  9  of the shell  5  to locate the blower unit  13  on the shell  5 . Cooperating connectors on the blower unit  13  and shell  5  detachably connect the blower unit  13  to the shell  5 . The connectors can comprise a first, male, connector member  25  on the collar  22  of the blower unit  13  adjacent the end wall  23  and a second, female, connector member  25 A on the shell  5  adjacent the end wall  9 . The connector members  25 ,  25   a  could be cooperating clasp members but any well known two-part connectors could be used to detachably connect the blower unit  13  to the shell  5 . Suitable seals (not shown) are employed between the duct  15  on the blower unit  13  and the end wall  9  of the shell  5  to provide an air-tight connection. 
     The air filter  3  employs a Hepa filter  27  having a tubular shape with a relatively thick wall as shown in  FIG. 4 . The Hepa filter  27  is preferably cylindrical and the wall of the filter is formed by outer and inner cylindrical wire mesh walls  31 ,  33  held together, one within the other, by annular end walls  35 . The space between the walls  31 ,  33  is filled with Hepa filtering material  37 . The Hepa filter  27  is mounted within the perforated shell  5  with the outer wall  31  of the filter adjacent the inner surface of the shell wall  6 . The Hepa filter  27  is retained adjacent the shell wall  6  by the end walls  8 ,  9 . One of the end walls  8 ,  9  is made removable to allow insertion/removal of the filter  27  within the shell  5 . The duct opening  17  on the duct  15  in the blower unit  13  is positioned within central space  39  within the Hepa filter  27 . 
     If desired, a sheath  45  of flexible filtering material can envelope the shell  5  to pre-filter the air passing through the shell  5  and the Hepa filter  27 . The sheath  45  is removable to clean it for reuse. The sheath can be made of suitable fabric material. The ends of the sheath can be elastic. 
     A relatively short outlet duct  47  of generally rigid, yet bendable, material can be mounted to the duct  15  at the duct opening  19  at the outer end of the blower unit  13 . The inner end  48  of the outlet duct  47  has a rigid collar  49  sized to fit over the duct  15  and abut the end wall  24  of the collar  22  on the duct  15 . The outer diameter of the inner end  48  of the duct  47  is preferably the same as the outer diameter of the collar  22  on the blower unit  13 . Clasp members  25  on the collar  22  will clamp on clasp members  25 A on the duct  47  to detachably connect the duct  47  in place on the blower unit  13 . The outlet duct  47  can be initially manipulated to direct the air from the blower unit  13  in the desired direction. A pressure gage (not shown) can be provided on the blower unit to measure the drop in pressure signifying that the pre-filter sheath is getting clogged and needs replaced and/or cleaning. 
     The filter unit  1  includes a carriage  51  to hold the air filter  3 . The carriage  51 , as shown in  FIGS. 1 and 2 , has an elongate frame  53  with a bottom support  55  on the bottom, front of the frame, receiving the bottom end wall  8  of the shell  5  of the air filter  3 . There is also an upper support  57  on the upper, front of the frame  53  spaced from the bottom support  55 . The supports  55 ,  57  are shaped to partly cradle the air filter  3  to support it on the carriage. Straps  59  extending from the frame  53  of the carriage  51 , adjacent the upper support  57 , can be used to hold air filter  3  on the supports  55 ,  57 . 
     The carriage  51  has a pair of wheels  61  mounted on the frame  53  adjacent the bottom support  55 . The wheels  61  could instead be mounted on the bottom support  55  adjacent the frame  53 . In either case, the wheels are positioned just behind and just above the bottom support  55  so that the wheels  61  do not touch the ground when the carriage  51  is upright but do touch the ground when the carriage  51  is tilted forwardly. A single swivel wheel  63  can be mounted on the frame  53  near the upper support  57 . The swivel wheel  63  can be pivoted from an inoperative position, close to the frame  53 , to an operative position where it is spaced farther from the frame  53 . 
     The carriage  51  carries leg means  64  in the form of a pair of support legs  65 , one on each side of the frame  53 , the legs pivoted by pivots  67  at their upper end to the frame  53  near the upper support  57 . The legs  65  are joined, near the pivots  67 , by a short u-shaped brace  69  that, when the legs  65  are detachably held inoperative against the frame  53 , is angled downwardly and slightly forwardly. The brace  69  normally extends past the inoperative swivel wheel  63  when the wheel  63  is in its inoperative position adjacent the frame  53 . The wheel  63  extends past the brace  69  when pivoted to an operative position. A handle  71  extends from the upper end of the frame  53 . While the leg means have been described as a pair of legs, one on each side of the frame, other leg arrangements can be used. 
     The filter unit  1  can be wheeled where needed by one person using the wheels  61  and the handle  71  of the carriage  51 . The carriage  51  can position the held air filter  3  in an upright position with the blower unit  13  on top, as shown in  FIG. 1 , when the carriage is standing on its flat, bottom support  55  on the ground. The carriage  51  can also position the air-filter  3  in a generally horizontal position if needed, close to the ground, when resting on its rear wheels  61  and the u-shaped brace  67  carried by the legs  65  on the frame  53 . If it is desired to reposition the air filter while in the horizontal position, the swivel wheel  63  can be employed to extend just past the brace  67  and the carriage can be rolled where needed on the wheels  61 ,  63  while in the horizontal position. The carriage  51  can also position the air filter  3  at an angle to the ground, if needed, as shown in  FIG. 3 . The legs  65  on the frame  53  are swung out away from the frame to be nearly transverse to the frame. Suitable stop means (not shown) limit the outward swing of the legs. With the legs  65  swung out, the carriage rests on the legs  65  and the wheels  61  at a preferred angle of about forty five degrees. The angle can range between about thirty five and fifty five degrees. The angled position of the air filter  3  makes it easier to position the outlet duct  47  in the direction you wish the air to flow from the unit. 
     The filter unit  1  can be used to clean the air in a room using the Hepa filter  27 , and, if desired or needed, the pre-filter  45 . A room might, for example, be undergoing renovations and there could be a lot of dust in the air in the room. In use, the filter unit  1  is wheeled into the room and set up in the best position to be out of the way of the workers while being able to filter the air. The fan  20  in the air filter  3  is then operated to draw room air into the unit through the perforations  7  in the wall  6  of the shell  5  and through the Hepa filter  27  into the center of the shell, out through the open end  9  of the shell through the blower unit  13 , and back into the room from the outlet duct  47 . The air, in passing through the filter unit, passes through the pre-filter sheath  45  outside the shell  5 , if the sheath is used, and then through the Hepa filter  27 , to remove the dust particles. Air is drawn in from all around the shell. The filter unit  1  can be utilized when it is on the ground resting on the back wheels  61  and the brace  67 ; when it is upright standing on the bottom support  55  on the frame  53 , or when it is resting on the legs  65  and wheels  61  at an angle to the ground. 
     In a preferred embodiment, as shown in  FIG. 5 , the air filter  3 A employs a rigid, cylindrical, tubular shell  5 A having inner and outer perforated walls  6 A,  6 B. The inner and outer walls  6 A,  6 B are joined at one end by the open end wall  9 A of the shell and at their other ends by the closed end wall (not shown). The inner and outer walls  6 A,  6 B are spaced apart to form an annular storage space  75 . The open end wall  9 A is removable to provide access to the space  75 . Filter medium  76 , in the form of granular material, either loose, or loosely encased in a porous sack  77  can be inserted into the space  75  to fill it up. The Hepa filter  27  is mounted next to the surface of the inner wall  6 B. The granular filter medium  76  can be designed to remove one or more specific, unwanted, contaminate elements from the air. An outer filter sheath  45  can still be used with this embodiment to pre-filter the air. 
     The unit  1  can employ elongate, flexible, tubing  80  to transport the filtered air to a desired location as shown in  FIG. 7 . The tubing  80  is lightweight and can be of the type supported by an internal coil of wire. The tubing  80  can be a single length of tube  81  where one end of the tube  81  is provided with male clasp member  25  and the other end of the tube is provided with female clasp member  25 A. The tube  81  can be attached on the outlet end of the generally rigid, short, outlet duct  47  by locating the tube end with female clasp member  25 A adjacent the outlet end of duct  47  which would carry male clasp member  25 . Alternatively, and preferably, the tube  81  can connect directly to the opening  19  of the duct  15  on the blower unit  13  with clasps  25 ,  25 A, the tube  81  replacing the duct  47 . The tube  81  would be located with its end carrying female clasp member  25 A adjacent the blower unit  13  carrying male clasp  25  at its end. 
     A support wand  83 , as shown in  FIG. 6 , can be attached to a portion of the tubing  80  near its unattached, open end  84  so that the operator can manipulate the open end  84  of the tube  81  with the wand  83  to a desired position. The wand can have an open, rigid, cradle-type frame  85  for the tube  81  with spaced apart straps  87  forming slings to hold the tube  81  in the frame  85 . The frame  85  has a handle  89  for manipulating the wand and thus the attached tube. 
     While the tubing  80  has been shown as a single tube  81 , it can comprise two or more tubes  81 A,  81 B,  81 C serially connected together. If needed, a second blower unit  13 A can be inserted between adjacent tubes  81 A,  81 B or  81 B,  81 C as shown in  FIG. 7 , to boost the air flow through the tubing. Again, detachable connectors such as clasps  25 ,  25 A connect the tubing, or the tubes  81 A,  81 B, etc. and the second blower unit  13 A, if needed, together. Each tube  81 ,  81 A, etc has a male connector at one end and a female connector at the other end. 
     Branch units could also be employed to distribute air from the filter unit  1 . For example a y-fitting  93  could be attached, via its stem  95  to the end of the tube  81  as shown in  FIG. 8  and a blower unit  13 E,  13 F could be attached in each branch  97 ,  99  of the y-fitting  93 . A tube  81 E,  81 F could lead from each blower unit  13 E,  13 F to a different location in the room. 
     The filter unit  1  is normally used for filtering and normally has the fan  21  draw air through the duct  15  from duct opening  17  to  19 . The blower unit  13  is mounted to have the duct opening  17  within the shell  5  to draw air out of the shell  5  into the blower unit and out of the filter unit. The filter unit can also be used without a filter to move air out of the room, using tubing  80  connected to the duct opening  19  of the blower unit  13 , if it is desired to ventilate the room or to under pressure the room for any reason. If desired or required however, the blower unit  13  can be reversed, locating duct opening  17  outside of shell  5 , and duct opening  19  within the shell  5  to draw air into the shell from the blower unit. In this configuration, the filter unit can be used with a filter to filter the air and return it to the room from the shell. The filter unit can also be used without a filter, and with tubing  80  now connected to duct opening  17  of the blower unit, to draw air into the room from outside the room to overpressure the room, if required for any reason. 
     The filter unit  1  can have a collector hood  105  for use with the tubing  80  and the air filter  3 . The collector hood  105  would be used to collect the air to be cleaned to direct it to the air filter  3  via the flexible tubing  80  connected to the blower unit  13 . The hood  105 , as shown in  FIG. 9 , would have a large air inlet  107 , about one to two square feet in area, on one side  109  of the hood and a small air outlet  111 , less than one square foot in area, on the opposite side  113 , of the hood. The hood  105  tapers down from the inlet  107  to the outlet  111 . The outlet  111  is cylindrical and a standard size to receive one end of the flexible tubing  80  used. The other end of the tubing  80  would be connected to the blower unit  13  on the air filter  3 . If needed, a booster blower unit  13 H could be inserted between the tubing  80  and the hood  105  as shown. The blower unit  13 H would have been set up to draw air into the tubing  80  from the collector hood  105  either by reversing the motor to change the direction of rotation of the fan or by changing the position of the blower unit relative to the hood. The collector hood  105  and the flexible tubing  80  would have co-operating connectors such as clasp members  25 ,  25 A for detachably connecting the tubing to the collector hood or for detachably connecting both the tubing  80  and the hood  105  to the booster blower unit  13 H. 
     When drawing the air into the collector hood  105 , since the hood tapers down from the inlet  107  to the outlet  111 , there is usually turbulence at the inlet  107  of the hood and a cloud of dust often surrounds the inlet of the hood. To minimize the dust cloud, and make air collection more efficient, the hood  105  can be modified by providing it with a double wall,  121 ,  123  which walls define a collecting channel  125  between them. Rim inlet openings  129  are provided in the outer wall  123 , and in the inner wall  121  as well, if needed, adjacent the rim  131  of inlet  107  to collect the dust cloud surrounding the inlet rim of the hood. The inner wall  121  ends short of the outer wall  123  at the outlet end of the hood providing an outlet  133  from the interior of the inner wall  121 . As the blower unit on the air filter, or the blower unit  13 H adjacent the hood  105 , draws air into the hood through the inlet  107 , as shown by the solid arrows, it also draws in the dust cloud that forms about the inlet  107  due to turbulence. The dust cloud air is drawn in through the rim inlet openings  129  as shown by the broken arrows and travels to the outlet  111  through the channel  125 . As the dust cloud air leaves the channel  125  just short of the outlet  111 , and passing the outlet  133  of the inner wall  121 , it combines with the air drawn in through the inlet  107  and the passage  135  formed by inner wall  121 , and the mixed air stream flows out of the hood, through the blower  13 H if used, and through the tubing  80  to the air filter (not shown). If desired, adjustable closure means  137  can be associated with each rim inlet opening  129  to adjust its size as needed. The closure means  137  can comprise slidable plates  139  that can mounted on the outer wall  123 , in suitable guide means (not shown), to slide over the rim inlet openings  129  to limit their size of as needed. Other closure means can be employed. While the hood has been provided with inlet openings  129  to collect the dust cloud about the hood inlet, other means can be employed to collect the dust cloud. 
     A plurality of filter units  1 K,  1 L,  1 M, etc. can be used in a large room area  141  to seal off a portion  143  of the room area to capture and clean the air  145  in the sealed-off portion as shown in  FIG. 10 . The units would be employed in an upright position and spaced apart and arranged like a fence  147  to separate the portion  143  to be cleaned from the remainder of the room area  141 .