Abstract:
A fluted filter element may include one or more bridging elements to provide resistance to telescoping of the layers of the fluted filter element. The bridging elements are attached to one or both of the filter faces via adhesives, and/or mechanical means, and may also take the form of one or more beads of adhesive applied across one or both ends of the filter element. The adhesive beads may include a flexible element, such as a string, or strip of material embedded in the adhesive bead.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Patent Application No. 60/761,203, filed Jan. 23, 2006, which is incorporated by reference in its entirety herein. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to fluid filters, and more particularly to the construction and use of filter elements having alternating layers of a face sheet material and a corrugated filter material, with the alternating layers forming substantially longitudinally oriented flutes for passage of a fluid to be filtered. 
     BACKGROUND OF THE INVENTION 
     Filter apparatuses of the type used for filtering particulate matter from fluid sometimes include a filter housing having an inlet for receiving the fluid with entrained particulate matter, and an outlet for delivering filtered fluid to a device needing fluid that is free of particulate matter. For example, a filter may be provided at the air inlet of an engine or an air compressor to remove dust, water, or other particulate matter that could cause damage to the engine or compressor if it were not removed from the air entering the engine or compressor. 
     In such filters, the bulk of the particulate matter is typically removed by a filter element that is installed within the filter housing in such a manner that the fluid must flow through the filter element, in traveling from the inlet to the outlet of the filter. The filter element typically includes a filter pack of porous filter material, which removes particulate matter from the fluid. Over time, the filter pack of the filter element becomes plugged or coated with particulate matter, necessitating removal and replacement of the filter element, in order for the filter element to continue in its function of supplying particulate-free fluid at the outlet of the filter. 
     A seal arrangement is provided at a juncture of the filter element in the housing, so that the fluid to be filtered cannot bypass the filter element while passing through the filter. Specifically, in one commonly utilized prior approach to providing a fluid filter, the filter element includes a media pack, a mounting flange attached to the inlet end of the media pack, and a seal support frame, which includes an annular axial extension thereof that projects axially from the outlet end of the media pack for supporting a seal. The seal is configured to seal radially and/or axially against the inner surface of the housing. 
     The seal support frame, of such prior filter apparatuses, typically includes integral webs extending completely across the outlet end of the media pack. These webs are sometimes provided for the purpose of resisting pressure forces acting on the media pack, which could cause the center of the media pack to bow outward in a downstream direction. It is heretofore been believed, by those having skill in the art, that such seal support frames having integral webs extending completely across the outlet face of the media pack were particularly necessary in media packs formed by stacking or coiling layers of corrugated filter material for a so-called “fluted filter,” in order to prevent the center of the filter media pack from telescoping in a downward direction under maximum rated inlet fluid pressure, particularly where the media pack is saturated with dirt or moisture. U.S. Pat. Nos. 6,190,432 and 6,610,117 to Gieseke, et al. disclose filter packs having seals attached to axially extending annular portions of a seal support frame which includes integral webs extending completely across the face of a media pack. 
     Having the seal mounted on an axially extending annular extension of a seal support frame, as has been done in the past, together with the space occupied by the webs at the outlet end of the filter pack, undesirably consume a significant portion of the volume inside of the housing, and in some instances cause the housing to be larger than it would have to be if the webbed, axially extending, seal support frame could be eliminated. 
     It is desirable, therefore, to provide an improved filter element, and filter apparatus in a form which better utilizes the volume inside of the cavity of the filter housing, while still providing means for precluding telescoping of the filter element. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides an improved filter element and filter apparatus, through use of a filter element having alternating layers of a face sheet material and a corrugated filter material, with the alternating layers forming substantially longitudinally oriented flutes that extend axially from a first end to a second end of the filter element, with the filter element further having one or more bridging elements attached directly to either or both of the first and second end of the filter element and joining adjacent layers of the filter element together. The bridging element provides resistance to telescoping of the layers of the filter element when the filter element is subjected to operating pressure differentials. 
     The bridging elements are attached to one or both of the filter faces via adhesives, and/or mechanical means. 
     In one form of the invention, one or more beads of adhesive are applied across one or both ends of the filter element. The adhesive may be any appropriate adhesive for use in the operating environment, including, for example, hot melt adhesives, or single or multiple part urethanes or epoxy. 
     In some forms of the invention, a bridging element may include a flexible element, such as a string, or strip of material embedded in an adhesive bead. The strip of material may take a variety of appropriate forms, including an amorphous, multiple parallel or twisted strands. Multiple separate strings or flexible elements may also be embedded in a common adhesive bead. 
     In other forms of the invention, the bridging element includes a rigid supporting part attached directly to one or both ends of the filter element. The rigid supporting part may be held in place by beads of adhesive applied beneath, or encapsulating the rigid supporting part. The rigid supporting part may include features such as outwardly extending posts, tabs, barbs, or other appropriate mechanical features for retaining the rigid supporting part on one of the ends of the filter element. For example, a rigid supporting part may take the form of a molded plastic cross, or web-like structure attached to an end of the filter element by beads of adhesive. Mechanical attachment features, such as barbed posts, may also be used for attaching the rigid supporting part to an end of the filter element. In embodiments of the invention utilizing a rigid supporting part with mechanical attachment features, the rigid supporting part may also be attached to an end of the filter element by an adhesive, in addition to the mechanical attachment features. 
     The invention may also take the form of a method for improving resistance of a fluted filter element to telescoping, through attachment of a bridging element, according to the invention, to one or both ends of the filter element. 
     Other aspects, objectives, and advantages of the invention will be apparent from the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective illustration of an exemplary embodiment of a filter element, according the invention, including a bridging element extending across one of the end faces of the filter element. 
         FIG. 2  is a perspective, schematic, illustration of the manner of forming a fluted filter medium according to the invention. 
         FIGS. 3 and 4  are perspective illustrations showing other embodiments of a filter element, according to the invention, including a bridging element having a rigid part extending across the face of the filter element. 
         FIGS. 5A-5E  are detailed illustrations of mechanical attachments extending from a rigid part, of a bridging element according to the invention, for rigid parts of the type shown in  FIGS. 3 and 4 . 
         FIG. 6  shows an exemplary embodiment of a filter apparatus, according to the invention, including a filter element having a bridging element attached to one end thereof. 
     
    
    
     While the invention will be described in connection with certain embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a first exemplary embodiment of the invention in the form of a filter element  10  having a media pack  12 . Referring to  FIG. 2 , the media pack is formed from a coil of alternating face sheets  14  and corrugated sheets  16  joined together to form a coil  18  of fluted filter material. 
     As shown in  FIG. 1 , the media pack  12  is wound around a longitudinal axis  20 , with the media pack  12  extending from a first end  22  to a second end  24  of the filter element  10 . It is noted that although the first and second ends  22 ,  24  of the filter element  10  of the exemplary embodiment are substantially flat and axially facing, in other embodiments of the invention, one or both of the first and second ends  22 ,  24  of the filter element  10  may take some other shape, such as rounded, spherical, conical, undulating, or other shapes appropriate to the design of the particular embodiment of the invention. 
     As shown in  FIG. 1 , the exemplary embodiment of the filter element  10  further includes a bridging element  26  having four beads of adhesive  28  extending across the first end  22  of the filter element  10 , and joining adjacent layers of the media pack  12  together across the first end  22  of the filter element  10 . In the exemplary embodiment shown in  FIG. 1 , the bridging element further includes strands of string  30  embedded in the beads of adhesive  28 . In other embodiments of the invention, it may be desirable and appropriate to utilize the beads of adhesive  28  without the embedded strings  30 . 
     It is noted, that although the exemplary embodiment of the filter element  10  shown in  FIG. 1  includes a bridging element  26  attached to only the first end  22  of the filter element, in other embodiments of the invention a bridging element, according to the invention, may be attached to either or both of the first and second ends  22 ,  24  of the filter element  10 . 
     As shown in  FIGS. 3 and 4 , in other embodiments of the invention, bridging elements  32 ,  34  may included a rigid part  36 ,  38  attached directly to one or both of the first and second ends  22 ,  24  of the filter element  10 . The rigid part may include straight legs extending across the end of the filter element, as shown in the rigid part  36  of  FIG. 3 , and in other embodiments of the invention, a rigid part  38 , as shown in  FIG. 4 , may include legs which are curved. In other embodiments of the invention, rigid parts, according to the invention, may include a combination of straight or curved legs, or other shapes having portions thereof extending at least partially across an end  22 ,  24  of the filter element  10  to bridge and join together adjacent layers of the media pack  12 . 
     In some embodiments of the invention, a bridging element, having a rigid part, such as those shown in  FIGS. 3 and 4 , may be joined to an end of the filter element  10  by an adhesive. The adhesive may be applied continuously or intermittently to a facing surface of the rigid part and/or the end of the filter element  10 , or in some embodiments, may encapsulate all or portions of the rigid part  34 ,  36 . 
     As shown in  FIGS. 5A-5E , a rigid part  40  may also include a mechanical attachment  42  projecting from the remainder of the rigid part  40  for engaging open ends of the flutes at one of the first or second ends  22 ,  24  of the filter element. Such mechanical attachments  42  may be utilized with or without beads of adhesive in various embodiments of the invention. Preferably, however, such mechanical attachments  42  would generally be used in conjunction with either continuous or intermittent beads of adhesive in the same manner as described above in regard to the description of the embodiment shown in  FIGS. 3 and 4 . 
     As will be understood, by those having skill in the art, the mechanical attachments  42  may take any appropriate form, such as the right circular cylindrical shaped posts shown in  FIGS. 5A and 5B , the rectangular cross-shaped tabs  42  shown in  FIGS. 5C and 5D , and may further include barbs  44 , as shown in  FIG. 5E . 
       FIG. 6  shows an exemplary embodiment of a filter apparatus  46 , according to the invention which includes a filter element  10 , as described above, inserted into a filter housing  48 , and sealed thereto by a seal member  50  which seals the juncture of the filter element  10  and the housing  48 . By the use of a bridging element  26 , according to the invention, a filter apparatus  46  is provided with a filter element  10  which is resistant to telescoping of the adjoining layers of the filter media pack  12  under pressure from the fluid flowing through the filter apparatus  46 . The bridging element  26  avoids the unnecessary complexity and wastage of space within the housing  48  attendant to use of the seal support members having integral webs extending across the face of the filter element in filter apparatuses prior to the invention. 
     The invention may be practiced in the form of a method for providing additional resistance to telescoping of a filter element, and/or a method for constructing a filter element having improved resistance to telescoping. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventor(s) for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor(s) expect skilled artisans to employ such variations as appropriate, and the inventor(s) intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.