Gas separation: processes – Solid sorption
Reexamination Certificate
2000-12-11
2002-12-10
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
Solid sorption
C095S143000, C096S135000, C096S153000, C055S385100, C055S512000
Reexamination Certificate
active
06491741
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to shaped adsorbent articles, filters utilizing the articles, and methods and assemblies of use. In particular, the invention relates to shaped adsorbent articles having projections extending from a main body of the article, filters utilizing the articles, and methods of use.
BACKGROUND OF THE INVENTION
Adsorbent filters have a variety of uses, including uses in electronic equipment and chemical manufacturing and storage. For example, in the computer industry, adsorbent filters are used within the housings or casings of electronic devices to protect the electronic components from contaminants, such as water vapor, acid gas, and volatile organic compounds. For example, disk drives often include adsorbent filters within the disk drive and/or provided over an opening in the disk drive housing to protect the drive components and the disks from contaminants, such as water vapor, hydrocarbons, and/or acid gas. Without such protection, these contaminants can lead to stiction, corrosion, and, in some instances, drive failure.
Typically, the adsorbent filter includes an adsorbent material, such as activated carbon or a desiccant, within the filter. In many conventional filters, the adsorbent material is typically provided as loose granular filter material or as filter material disposed on a polymer carrier. The presence of granular adsorbent material can produce particulate contamination, particularly if a covering around the filter material is cut or torn open. The addition of a polymer carrier reduces the density of the adsorbent material because of the presence of the carrier and/or air pockets in the adsorbent material. In addition, the polymer carrier/adsorbent material is typically punched or otherwise cut to form the desired shape, often loosening particles from the carrier which can then become contaminants. Compression molded adsorbents are described, for example, in U.S. patent application Ser. No. 08/819,851 now U.S. Pat. No. 5,876,487. However, compression molded adsorbents may, at least in some instances, provide obstruction to fluid flow and thereby substantially increase the pressure drop over a filter. Thus, there is a need for new materials and designs of adsorbent filters to increase filter efficiency and/or to prevent or reduce contamination by the adsorbent material itself.
SUMMARY OF THE INVENTION
Generally, the present invention relates to shaped adsorbent articles for use in adsorbent filters. In particular, the present invention includes articles, assemblies, and methods of use that have or use a shaped adsorbent article having at least one projection extending from a surface of the article to permit fluid flow, e.g., air flow, between a filter housing and the shaped adsorbent article. In some instances, the shaped adsorbent article is a molded or compression molded adsorbent article.
For example, a filter assembly may include a housing and a shaped adsorbent article disposed in the housing. The housing defines an internal volume and has first and second openings for flow of a fluid, such as air, into and out of the internal volume. The shaped adsorbent article has a plurality of projections extending from at least one surface of the article toward the housing to provide for flow of fluid between the shaped adsorbent article and the housing. The filter assembly may be used in a device, such as a computer disk drive, to filter air within and/or entering or exiting the device.
Another example is an adsorbent filter assembly having a housing, a diffusion channel defined in the housing, and a molded adsorbent article. The housing defines an internal volume and includes a first opening and a second opening with the diffusion channel extending from the first opening to the internal volume of the housing. The molded adsorbent article is disposed within the internal volume of the housing and has at least one surface with a plurality of projections extending from the surface toward the housing to provide for fluid flow between the article and the housing. In some instances, the assembly also includes a porous film disposed over the second opening and/or adhesive disposed on the housing to adhere the housing to a device, such as a computer disk drive.
Another example is an adsorbent filter assembly as described above, except the molded adsorbent article has a single projection extending from the surface toward the housing to provide for fluid flow between the article and the housing. The single projection may be centrally positioned on the surface of the molded adsorbent article, and may extend or expand over the entire surface. A single such projection may be disposed on each of two opposite surfaces of the molded adsorbent article.
Yet another example is a method of filtering a fluid. A fluid, such as air, flows through an inlet opening in a housing of a filter assembly. The fluid then flows across a shaped adsorbent article disposed within the housing. The shaped adsorbent article has at least one projection extending from at least one surface of the article to direct fluid flow between the projections and between the shaped adsorbent article and the housing. This method can be used to protect a computer disk drive from contaminants.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and the detailed description which follow more particularly exemplify these embodiments.
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Dahlgren Andrew C.
Garikipati Vijay
Logan Randy J.
Tuma Daniel L.
Donaldson & Company, Inc.
Spitzer Robert H.
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