Gas separation – With means securing or retaining separating media – Unit or cohesive sheet-like media in flow line or frame
Reexamination Certificate
2001-10-12
2004-05-25
Smith, Duane (Department: 1724)
Gas separation
With means securing or retaining separating media
Unit or cohesive sheet-like media in flow line or frame
C055S500000, C055S501000, C055S502000, C055S503000, C055S507000, C055S509000, C055S511000, C055S514000, C055S521000, C055S524000, C055SDIG003
Reexamination Certificate
active
06740136
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to a multiple element framing construction for making a frame about filter media to create a framed filter product that may be shaped for a specific application. In particular, the present invention is directed to such a framing construction and method of assembly whereby multiple frame components are assembled together so as to position and hold filtration media in place.
BACKGROUND OF THE INVENTION
Filter products typically include a quantity of filtration media and a frame that is not only sized and shaped to partially enclose and support the filtration media, but also sized and shaped so that the filter product can be inserted or supported in place based upon a particular application. Conventionally, filter frames have been constructed from multiple elements that are assembled together or connected to the filtration media, such as about its perimeter, so as to provide the support and application-specific filter frame. Such frame elements are known to be made from a variety of materials, including metals, plastics, and paperboard. In the case of a rectangular filter product, for example, a rectangular filtration media is surrounded at its four sides by frame pieces that may be connected at the comers and/or connected to the four side edges of the filtration media. The majority of the filtration media is thus capable of use for its filtering ability.
Moreover, these typical frame elements comprise three-dimensional elements that are sized and shaped to partially enclose the filtration media at its edges. The frame may comprise multiple pieces assembled by use of adhesive, welding, friction fit, snap fits, mechanical fasteners, or like. Otherwise, the entire frame or any selective portion thereof may be made integral. That is, a frame portion comprising multiple elements made together may be provided, such as, for example, by an injection molding process. In any case, the one or more frame elements must be assembled and connected with the filtration media by a selective assembly process. Such a selective assembly process requires manipulations of the elements for assembly.
Many types of filter products have also been developed for many different types of applications. Applications often are based in large part upon the characteristics of the filtrate and the carrier fluid and upon the support requirements of the system of the particular application. Filtering requirements may make it necessary to construct the filter products under construction specifications that ensure that all carrier fluid and filtrate must pass through the filter product. This may require appropriate sealing mechanisms between the frame and its system support, for example by one or more gaskets, and between the frame and the filtration media, for example by adhesive sealant. Such adhesive sealant may be provided as a bead extended along the entire frame at an interface between the frame and the filtration media. For example, a typical high-efficiency particulate air (HEPA) filter uses pleated filtration media sealed about its edges to a frame that is provided about its complete perimeter. Thus, the filtration media and frame provide a fluid tight assembly that prevents bypass of unfiltered carrier fluid.
Some filter products require frames that hold and support the filtration media in place. For example, the filtration material may be supported as pleated filtration media sized and shaped for a particular application. Such framing elements may be responsible for maintaining the pleats and supporting the filtration media in position (i.e. spacing and properly orienting the pleats of the filtration media). This supporting function may be done by frame elements having pleat shaped supports that can be provided to contact the filtration media along one or more of the edges of the pleated filtration media and/or at intermediate locations. That is, the pleat supporting element may be separate from the side edge frame elements. An example of such an element that is connected with the edge frame is described in U.S. Pat. No. 2,058,669 to Dollinger.
Other frame constructions support such a pleated filtration media in position from side edge support features that also connect the edges of the filtration media to the frame elements to make sure that substantially all carrier fluid and filtrate passes through the filtration media portion of the filter product. As examples, U.S. Pat. No. 4,617,122 to Kruse et al, Japanese published unexamined application Hei 9-276637 and French published application no. 795656 describe rectangular edge frames having pleat shaped supporting features for supporting parallel spaced side edges of pleated filtration media and a hold down frame having cooperating features for meshing with those of the frame to hold the filtration media in position. The Kruse et al and Japanese references disclose, in particular, that such pleat supporting features comprise a pleat shaped surface formed as a ledge adjacent to and extending along a side wall of the supporting frame or the hold down frame, respectively, with the other frame component having a similarly defined edge. The French reference discloses such a pleat shaped surface that comprises the upper edge of its frame element and a lower edge of its hold down frame.
The cooperating side edge supporting features of these prior art filter frames effectively support the pleated filtration media along a pair of spaced side edges, and these supporting features further pinch or crimp the spaced edges of the filtration media. However, such pinching or crimping structures tend to crush the media along the filtration media edges, which crushing can produce powdered media and/or dislodged particulate material contained in the media (from filtration media granules, such as carbon) that can become lost from the filtration media. Also, such a pinching or crimping action tends to cause the filtration media to shift inward from the pinched or crimped edges, which shifting can cause the filtration media to become loose or not effectively supported at edge portions.
Also, some filter products, including those of the type having filtration media supporting features for pleats, are designed to provide for replaceable filtration media. Typically, the filtration media is accessible by removing one or more of multiple frame portions from another. That is, a frame element, such as might include a pleat supporting feature, may be removed so as to permit the filtration media to be removed. Then, a new quantity of filtration media may be supported in position followed by reassembling the frame elements to create a filter product with new filtration media. The aforementioned Kruse et al US patent, Japanese published application and French published application disclose the possibility of removing and replacing the filtration media.
SUMMARY OF THE PRESENT INVENTION
The present invention overcomes the deficiencies and shortcomings of the prior art by providing a filter product having filtration media combined with a multi-component frame assembly that can effectively support the filtration media in place proximal to its edges and in accordance with its desired orientation and wherein the assembly can be selectively taken apart to provide access to the filtration media by way of a releasable lock connection. Preferably, a snap-fit releasable locking system is incorporated within the frame design.
Moreover, the present invention provides for the supporting of the filtration media proximal to its edges and to preferably at least slightly compress the filtration media proximal to its edges so as to effectively seal the filtration media with the frame components. Specifically, support features are preferably provided from plural cooperating components so that the support features work together in a meshing relationship to support and preferably compress the filtration media and to sealingly connect the filtration media to the frame.
The present invention is particularly applicable to filtration media comprising pleated filtrati
3M Innovative Properties Company
Bond William J.
Greene Jason M.
Griswold Gary L.
Smith Duane
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