Abstract:
A collecting electrode element for an electrostatic air cleaner with a reduced weight can be constructed with a lightweight conductive core sandwiched between particle collection layers which are supported and stabilized by a rigid frame. The conductive core may be conductive foil, conductive film, conductive ink, or conductive glue. The particle collecting layers may be flexible open-cell foam such as melamine which may be compressed between opposing frame elements. The frame may leave most and preferably at least 90% of the surface of the particle collecting layers exposed. The frame may have opposing frame elements secured to each other at a compressed area of the particle-collecting layers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0001]    The present invention relates to an electrode device such as an electrostatic air filter. More particularly, the present invention relates to a light weight collector electrode capable of collecting airborne particles, such as dust, before becoming saturated and in need of disposal or cleaning. 
       2. Description of the Related Technology 
       [0002]    US Patent Publication No. 2015/0323217 entitled “Electronic Air Cleaners and Associated Methods” is expressly incorporated by reference herein and shows an electrostatic air cleaner with collecting electrodes that have an internal conductive portion sandwiched between collecting portions of open-cell, porous material. The prior art discloses that melamine foam may be used which is not flammable and has good porosity for collecting large amounts of dust. The prior art discloses that the internal conductive portion may be a metal plate, metal grid, a conductive film, or conductive ink. A drawback to the use of conductive film or ink is that it is not a rigid structure that will support otherwise flexible melamine foam. The prior art disclose that a rigid collecting material or a metal plate must have considerable thickness to be sufficient to keep all structures solid and rigid. Such structures may lead to heavy and expensive collecting electrodes. Typical electronic air cleaners contain a plurality of collecting electrodes. 
         [0003]    In addition it is not practical and is wasteful to dispose of expensive metal plates. 
         [0004]    It may be labor intensive and expensive to replace heavy collecting electrode assemblies due to inconvenient. Light-weight and inexpensive internal conductive parts like conductive film cannot support the collecting electrodes. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to provide lightweight, disposable, collecting electrode structures with sufficient rigidity to be used in electrostatic air cleaners. 
         [0006]    A collecting electrode structure may include a rigid frame made of inexpensive plastic material. The rigid frame may be lightweight. The frame may include similar parts secured to two layers of porous, open-cell material with a conducting layer there between. This frame may define openings that expose most of the porous, open-cell material to the air. The exposed areas of the porous open-cell material may serve as the dust collection sites. The open-cell material may be a flexible structure which may be squeezed between two complementary frame parts under sufficient force. The frames may firmly hold the porous open-cell flexible material. The total thickness of the collecting electrode structure at the frame may advantageously be the same as the thickness of two layers of the porous open-cell material with a conducting layer there between. 
         [0007]    According to an advantageous feature, a lightweight frame made of inexpensive plastic material may be used. The frame may have two similar parts between which the porous, open-cell material may be secured. The frame may define openings to expose most of the porous, open-cell material to the air for dust collection. Due to the open-cell flexible structure, the porous material may be squeezed between the two frame parts and be firmly kept by them. The electrode&#39;s total thickness is defined by the total thickness of the two parts together with any compressed open cell material and conductive layer, preferably will be the same as the collection portion thickness, i.e., two uncompressed layers of open-cell material with a conductive layer therebetween. 
         [0008]    A collecting electrode element may have a first particle collecting layer having a porous external surface, a conductive layer adjacent to said first particle collecting layer on a side of said first particle collecting layer opposite of said porous external surface, a second particle collecting layer having a first side adjacent to a side of said conductive layer opposite said first particle collecting layer and having a porous external surface on a side of said second particle collecting layer opposite and said conductive layer, and a rigid frame supporting said particle collecting layers. 
         [0009]    The rigid frame may have a first frame element on the side of the first particle collecting layer having a porous external surface and a second frame element. 
         [0010]    The frame elements may be configured to define open areas exposing most of the sides of the first and second particle collecting layers having porous external surfaces. The open areas may expose at least 90% of the sides of said particle collecting layers having the porous external surfaces, i.e., a portion of the first particle collecting layer and a corresponding portion of the second particle collecting layer. The thickness of the frame elements and corresponding compressed particle collection layers may be equivalent to the thickness of uncompressed first particle collecting layer plus the thickness of compressed second particle collecting layer. The conductive layer may be a conductive film, a conductive foil, conductive ink, or conductive glue. 
         [0011]    Various objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components. 
         [0012]    Moreover, the above objects and advantages of the invention are illustrative, and not exhaustive, of those that can be achieved by the invention. Thus, these and other objects and advantages of the invention will be apparent from the description herein, both as embodied herein and as modified in view of any variations which will be apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows an exploded view of a dust-collecting electrode. 
           [0014]      FIG. 2  schematically illustrates an assembled dust-collecting electrode. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Before the present invention is described in further detail, it is to be understood that the invention is not limited to the particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
         [0016]    Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. 
         [0017]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary methods and materials are described herein. 
         [0018]    It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
         [0019]    All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed. 
         [0020]    An electrostatic device may operate as an electrostatic air cleaner as a standalone device, integrated into an HVAC system or otherwise deployed. For example, according to one configuration an electrostatic air cleaner may be provided with a face size of 2′×2′. Such an air cleaner may have approximately 20 collecting electrode elements. Each collecting electrode element may be dimensioned to span the face of the cleaner (corresponding to 24″) and a depth of 4″ to 8″. By way of example a set of 20 collecting electrode elements which are 24″×8″ and made of steel sheets may weigh 40 pounds or more. 
         [0021]    The weight of the collecting electrodes may be reduced substantially by reducing the weight of the inner conductive layer. 
         [0022]      FIG. 1  shows an exploded view of components of a collecting electrode element  101  with reduced weight. The collecting electrode element  101  may include plastic frame elements  105  and  106 , collection layers  102  and  104 , and an internal conductive portion  103 . 
         [0023]    Advantageously the plastic frame elements  105  and  106  are sufficiently rigid to support and stabilize the collection layers  102  and  104  made of flexible material like an open cell foam. The frame elements  105  and  106  may have large openings ensuring that most of the external surface of the collecting layers  102 ,  104  are exposed for dust collection function. The internal conductive layer  103  may be made of an inexpensive, lightweight conductive material like conductive film, conductive glue, or conductive ink. The latter may be simply sprayed or applied to a surface of the outer collecting layer(s)  102  and/or  104 . 
         [0024]      FIG. 2  shows a schematic of a collecting electrode  101  as assembled. Two plastic frames  105  and  106  may be attached to each other. The outer collection layers  102  and  104  may be squeezed between the frames  105  and  106 . Collection layers  102  and  104  and conducting layer  103  are sandwiched together by the frame elements  105 ,  106 . 
         [0025]    The collection layers  102  and  104  may be flexible sheets made of porous open-cell foam, such as melamine each with a thickness of about 4 mm. When compressed the thickness of the collections layers may be reduced dramatically for example to 1 mm each. When the collection layers  102 ,  104  are compressed between the plastic frame elements  105 ,  106 , the width of the assembly may be only slightly larger than the width of the two plastic frame elements  105 ,  106 . 
         [0026]    The collecting electrode assembly may have the same thickness as two uncompressed layers of open-cell 4 mm thick foam together (i.e., 8 mm). 
         [0027]    The plastic frame elements  105 ,  106  may have a width of about 6 mm in order to create a rather strong structure. By way of example the collecting electrode element has the same overall dimensions as in the example above (i.e., 20 collector elements, 8″ by 24″), the weight of all 20 collecting electrode elements totaling about 1.25 lbs. 
         [0028]    Taking into account that plastic is substantially cheaper than metal, one can appreciate the total weight and cost savings that the present invention may offer. 
         [0029]    At the same time, about 90% of the collection surface area of the porous dust-collecting portion is exposed for dust collection. 
         [0030]    It should be taken into account that the collecting electrodes are exposed to substantial air velocity. Front or tail surfaces perpendicular to the general direction of air flow present resistance to air flow and induce turbulence. It is possible to reduce the resistance and induced turbulence by providing the collecting electrode assemblies with more aerodynamic front and tail portions. According to an embodiment, the front portion may be rounded. According to an embodiment, the tail portion may be tapered. 
         [0031]    The techniques, processes and apparatus described may be utilized to control operation of any device and conserve use of resources based on conditions detected or applicable to the device. 
         [0032]    The invention is described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention. 
         [0033]    Thus, specific apparatus for and methods of a dust collecting electrode have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure. Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.