Patent Publication Number: US-6989051-B2

Title: Portable air filtration system

Description:
RELATED APPLICATIONS 
   This application is related to co-pending U.S. Pat. application Ser. No. 10/647,482 entitled “Portable Air Filtration System Utilizing A Conductive Coating And A Filter For Use Therein” which is commonly assigned and was filed on the same date as the present application. Each application is directed to a different invention. 
   TECHNICAL FIELD 
   The subject invention generally relates to a portable air filtration system for filtering air. The portable air filtration system of the subject invention is primarily for use in vehicles but may also be used to filter air in rooms of commercial and residential buildings. 
   BACKGROUND OF THE INVENTION 
   Air filtration systems are known in the art. Many of these air filtration systems utilize ionization to enhance efficiency of a filter used within the air filtration system. The air filtration systems of the prior art are deficient for a variety of reasons. 
   One example of a prior art air filtration system is disclosed in U.S. Pat. No. 4,940,470 to Jaisinghani et al. With particular reference to  FIG. 1  of the &#39;470 patent, this air filtration system is deficient because the electrode E, a ground electrode, is positioned downstream from the filter F. As such, the filter F is disposed within the electric field that is established between the ionizing wires W and the electrode E. Ultimately, this particular air filtration system presents a safety hazard as the filter F may be exposed to arcing that occurs in the electric field. The filter F may catch fire, destroy the air filtration system, and be dangerous to users of the air filtration system. 
   A further example of a prior art air filtration system is disclosed in U.S. Pat. No. 5,403,383 also to Jaisinghani et al. With particular reference to  FIG. 1  of the &#39;383 patent, this air filtration system is deficient for the same reason identified above with respect to the &#39;470 patent. That is, the ground electrode  106  is positioned downstream from the filter  114  such that the filter  114  is disposed within the electric field that is established between the ionizing wires  110  and the ground electrode  106 . This position of the ground electrode  106  presents the same safety issues described above, i.e., exposure of the filter  114  to arcing in the electric field. However, the air filtration system disclosed in the &#39;383 patent is also deficient because it requires two electrodes that are separate from one another, a control electrode  104  and a downstream ground electrode  106 , for sufficient ionization. The requirement for this additional componentry is unnecessary. Therefore, the design for this air filtration system is not optimized and is unnecessarily expensive. 
   Finally, many of the air filtration systems of the prior art are deficient in that they are not sufficiently portable. That is, many air filtration systems are heavy, bulky, and awkward. For example, many air filtration systems do not include a handle for conveniently carrying the air filtration system from vehicle to vehicle or from room to room. Other air filtration systems include a filter housing that is constructed of a metal which tends to add weight to the air filtration system and makes it heavy to carry. 
   Due to the various deficiencies associated with the air filtration systems of the prior art, including those described above, it is desirable to provide a novel air filtration system that is safe, portable, and has simplified componentry yet still achieves enhanced filtration of particles from air. 
   SUMMARY OF THE INVENTION 
   A portable air filtration system for filtering air is disclosed. The air filtration system includes a filter housing, an intake fan, an ionizing mechanism, a filter media, and an electrode. More specifically, the filter housing includes an air inlet and an air outlet and defines a filtration chamber between the air inlet and the air outlet. The intake fan is disposed within the filter housing to move the air through the filtration chamber by drawing the air in through the air inlet and dispelling the air out through the air outlet. The ionizing mechanism, which is disposed between the intake fan and the air outlet, ionizes particles within the air to a negative charge. The filter media is disposed between the ionizing mechanism and the air outlet for entrapping the particles. 
   The electrode is disposed between the ionizing mechanism and the filter media. As a result, an electric field is established between the ionizing mechanism and the electrode adjacent to the filter media. Therefore, the filter media is not within the electric field. In addition, the electrode is electrically-connected to ground and to the filter media. The negative charge of the particles that are entrapped within the filter media is dissipated through the electrode. 
   Accordingly, the subject invention provides a novel air filtration system that is safe. More specifically, because the filter media is not within the electric field, the filter media is not exposed to any arcing within the electric field and is not susceptible to catching fire. Furthermore, the air filtration system of the subject invention eliminates the need for a separate control electrode and ground electrode. Instead, this air filtration system simplifies the required componentry by integrating the control electrode and the ground electrode into a single electrode. This single electrode provides a plane for establishing the electric field with the ionizing mechanism and also provides a ground for dissipating charges in the filter media. It is also advantageous that the air filtration system of the subject invention is portable. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
       FIG. 1  is a perspective view of a portable air filtration system of the subject invention; 
       FIG. 2  is a perspective view of an alternative embodiment of the portable air filtration system illustrating adjustable louvers as an air outlet; 
       FIG. 3  is a partially cross-sectional perspective view of the portable air filtration system; and 
       FIG. 4  is a schematic representation of the portable air filtration system illustrating flow of air across an ionizing mechanism, an electric field, an electrode, and a filter media. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a portable air filtration system is generally disclosed at  10 . For descriptive purposes only, the portable air filtration system  10  of the subject invention is hereinafter referred to as the filtration system  10 . 
   Preferably, the filtration system  10  is used to filter air in a vehicle. In such an embodiment, the filtration system  10  can be placed on a floor, on a seat, or on any other suitable surface within the vehicle. As such, the filtration system  10  can be adapted to be secured on the surface by a standard safety restraint system, i.e., a seatbelt. However, the filtration system  10  of the subject invention may also be used to filter air in rooms of commercial and residential buildings. 
   Although not required, it is most preferred that the filtration system  10  include a handle  12  that is integrated into the filter housing  14 . The handle  12  enhances the portability of the filtration system  10 . As such, the filtration system  10  is mobile and can be conveniently moved from vehicle to vehicle or from room to room. As disclosed in  FIG. 3 , the handle  12  can be integrated into a filter housing  14  simply by being a recess within the filter housing  14  that can be accessed by a hand. Alternatively, although not disclosed in the Figures, the handle  12  can be integrated into the filter housing  14  by extending, either in a fixed manner or in a pivotable manner, from the filter housing  14 . 
   Referring particularly to  FIGS. 3 and 4 , the filtration system  10  includes a filter housing  14 , an intake fan  16 , an ionizing mechanism  18 , a filter media  20 , and an electrode  22 . Each of these components are described additionally below. 
   The filter housing  14  includes an air inlet  24  and an air outlet  26 . The filter housing  14  also defines a filtration chamber  28  between the air inlet  24  and the air outlet  26 . As schematically represented in  FIG. 4 , the air flows through the filtration chamber  28  where particles which are typically present in the air, such as dust, lint, pollen, allergens, and the like, are filtered. It is preferred that the filter housing  14  is plastic. That is, it is preferred that the filter housing  14  is made from a non-metal material that is either a thermoplastic or thermosetting polymeric material. To further enhance the transportability of the filtration system  10 , the filtration system  10  is compact with the filter housing  14  having approximate dimensions of 390×190×170 mm. These dimensions can vary. However, the filtration system  10  of the subject invention provides a high level of clear air delivery rate (CADR) for such a compact unit. 
   Referring to one preferred embodiment disclosed in  FIG. 1 , the air inlet  24  is further defined as inlet louvers  30  and the air outlet  26  is further defined as outlet louvers  32 . Both the inlet louvers  30  and the outlet louvers  32  are defined within the filter housing  14 . 
   Referring to the most preferred embodiment of the subject invention, as disclosed in  FIG. 2 , at least one of the inlet louvers  30  and the outlet louvers  32  are adjustable. With the filtration system  10  disclosed in  FIG. 2 , only the outlet louvers  32  are adjustable. Although it is not disclosed in the Figures, it is possible for the inlet louvers  30  to be adjustable also. 
   The controllability, i.e., the ability to manipulate an angle, of the outlet louvers  32 , is important so air exhausted out from the filtration system  10  can be targeted at a level where most occupants of a vehicle inhale and exhale. It is estimated that this level is achieved by angling the outlet louvers  32  approximately 60° upward, assuming the filtration system  10  is positioned on the seat of the vehicle. The range of angle for the outlet louvers  32  is typically 60° to 90°. 
   Referring to  FIG. 3 , the intake fan  16  is disposed within the filter housing  14 . The intake fan  16  moves the air through the filtration chamber  28  by drawing the air in through the air inlet  24  and dispelling the air out through the air outlet  26 . Preferably, the intake fan  16  is a centrifugal fan. It is also preferred that a speed of the intake fan  16  can be controlled such that users of the filtration system  10  can select a desired amount of filtering with a desired amount of noise level. As such, it is preferred that the filtration system  10  include an adjustment knob  34  that can be adjusted from low to high to control the speed of the intake fan  16 . Clearly, increasing the speed of the intake fan  16  draws more air in through the air inlet  24  to be filtered but produces more noise, and vice versa. 
   Furthermore, although it is not required, the filtration system  10  preferably incorporates a pre-filter  36  between the air inlet  24  and the intake fan  16 . The pre-filter  36 , typically an activated carbon pre-filter, is primarily used to absorb odors present in the air as the air is drawn in through the air inlet  24 . 
   The ionizing mechanism  18  is disposed between the intake fan  16  and the air outlet  26 . In this position, the ionizing mechanism  18  ionizes the particles within the air to a negative charge, i.e. a negative state. Preferably, the ionizing mechanism  18  is further defined as a plurality of ionizing needles. More specifically, in the most preferred embodiment of the subject invention as disclosed in  FIG. 3 , the plurality of ionizing needles is further defined as a first  38 , second  40 , third  42 , and fourth  44  ionizing needle. Any suitable number of ionizing needles can be utilized without varying the scope of the subject invention. 
   The filtration system  10  includes a high voltage power supply  46 . The high voltage power supply  46  of the filtration system  10  is electrically-connected to the ionizing mechanism  18  and is electrically-connected to an energy source of the vehicle. For example, as disclosed in  FIGS. 1 and 2 , the filtration system  10  includes an adapter  48 . The adapter  48  extends from the high voltage power supply  46 . This adapter  48  is designed to insert into a cigarette lighter, or other port, in the vehicle and to tap into the energy source, such as a 12V battery, of the vehicle. It is preferred that the filtration system  10  also includes a circuit that incorporates a unique shut-off feature to protect a charge of the battery of the vehicle. There is also a DC—DC power converter incorporated into the circuit for supplying power to the filtration system  10 . If the filtration system  10  of the subject invention is to be used in the rooms of commercial and residential buildings, then the high voltage power supply  46  of the filtration system  10  is operatively connected to an electrical system of the building, and a different adapter is utilized to plug into an electrical outlet. 
   To effectively ionize the particles within the air, the high voltage power supply  46  supplies a high voltage, approximately −15 kV, to the ionizing mechanism  18 . However, this high voltage is at a very low amperage, less than 1 milliamp, such that less than 10 W of power is required overall. 
   The filter media  20  is disposed between the ionizing mechanism  18  and the air outlet  26 . Ultimately, the filter media  20  entraps the particles yet allows the air to pass through the filtration system  10 . As described additionally below, the filter media  20  is an electrically-enhanced filter (EEF) media and preferably can be removed from the filter housing  14  for replacement purposes over time. With particular reference to the Figures, the filter media  20  includes an upstream side  50  and a downstream side  52 . The upstream side  50  faces the air inlet  24  and the downstream side  52  faces the air outlet  26 . Several different filter media  20  are suitable for use in the filtration system  10  of the subject invention including, but not limited to, woven filter media, non-woven filter media, and cellular filter media. 
   The electrode  22  is disposed between the ionizing mechanism  18  and the. filter media  20  to establish an electric field between the ionizing mechanism  18  and the electrode  22 . The electric field that is established is adjacent to the filter media  20 . That is, the filter media  20  is not actually within the electric field. As such, the particles within the air are ionized upstream of the filter media  20  and no fire and/or other safety hazard is present with the filtration system  10  of the subject invention. 
   The electric field has a distance D, defined between the ionizing mechanism  18  and the electrode  22 , that has been optimized to control an ionization current applied to the particles and to prevent ozone generation, which is an additional deficiency associated with the air filtration systems of the prior art. The distance D has been optimized to range from 35 to 60, preferably from 40 to 50, mm. 
   As disclosed schematically in  FIG. 4 , the electrode  22  is electrically-connected to ground  54 . The electrode  22  is also electrically-connected to the filter media  20  for dissipating, i.e., bleeding, the negative charge of the particles that become entrapped within the filter media  20 . More specifically, the electrode  22  is electrically-connected to the upstream side  50  of the filter media  20 . Therefore, the negative charge of the particles entrapped with the filter media  20  is dissipated through the upstream side  50 . For the negative charge of the particles entrapped within the filter media  20  to dissipate to ground  54  through the electrode  22 , it is important that the filter media  20  be slightly conductive. That is, although the filter media  20  is ‘relatively’ dielectric and is, therefore, a poor conductor as compared to the conductivity of the electrode  22 , the filter media  20  still must possess some degree of conductivity for the charge to dissipate to ground  54  through the electrode  22 . 
   As described above, the electrode  22  is electrically-connected to the filter media  20 . To establish this electrical connection, it is preferred that the electrode  22  is in direct contact with the filter media  20 . However, it is to be understood that the electrode  22  is not required to be in direct contact with the filter media  20  for the electrical connection to be present. Instead, the electrode  22  may be spaced from the filter media  20  and may be indirectly electrically-connected to the filter media  20  in any other suitable manner such as, for example, relying on additional componentry. 
   With the electrode  22  in this position, i.e., upstream of the filter media  20 , and with the electrode  22  electrically-connected to both ground  54  and the filter media  20 , the electrode  22  is able to perform two functions. First, the electrode  22  of the subject invention provides a plane for establishing the electric field with the ionizing mechanism  18 , which is normally the function of a discrete control electrode that is separate from a ground electrode. Secondly, the electrode  22  of the subject invention provides a ground  54  for dissipating charges present in the filter media  20 , which is normally the function of a discrete ground electrode that is separate from a control electrode. Because the electrode  22  of the subject invention integrates the function of the two separate electrodes present in the prior art, the filtration system  10  of the subject invention has simplified componentry. 
   Referring particularly to  FIGS. 3 and 4 , the electrode  22  is further defined as a conductive grid  56 . The conductive grid  56 , functioning as the electrode  22 , is electrically-connected to the upstream side  50  of the filter media  20 . The conductive grid  56  can be metallic, i.e., a conductive metal, or conductive plastic. The most preferred conductive grid  56  is aluminum. The conductive grid  56  is adhesively bonded to the filter media  20 . For example, a chemical adhesive that is conductive can be used to adhere and therefore electrically-connect the conductive grid  56  to the filter media  20 . The electrode  22 , and more specifically the conductive grid  56 , can be electrically-connected to the filter media  20  in any other suitable manner including, but not limited to, using electrically conductive connectors and fasteners between the electrode  22  and the filter media  20 . In an alternative embodiment of the subject invention, the electrode  22  is further defined as a conductive coating that is applied to the filter media  20 . In this embodiment, the conductive coating is more specifically applied to the upstream side  50  of the filter media  20 . 
   The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.