Abstract:
A filter element is particularly suitable as a “green” filter element because all of its parts are flammable for disposal of after use by incineration. The filter element has an annular pleated filter media, hard resinous end seals and compressible gaskets bonded directly to the end seals. In accordance with one embodiment, both the end seals and gaskets are applied to the ends of the filter media by sequential steps in an injecting molding machine. In accordance with another embodiment, the gasket is molded to the end cap to form an integral assembly and the end cap is then fixed to the filter media by adhesive or by heat bonding.

Description:
This application is a divisional application of U.S. patent application Ser. No. 10/319,278, filed Dec. 16, 2002, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to improvements in end cap and gasket assemblies for filter elements, and more particularly, to techniques for securing end caps and gaskets to one another and to filter media. 
     BACKGROUND OF THE INVENTION 
     Green filter elements are filter elements comprised of flammable components allowing the filter elements to be disposable by incineration after use. Green filter elements do not contain metal components. Since by law, used lubricating oil from internal combustion engines is 100% recycled, it is also now becoming the practice to recycle lubricating oil filters by completely incinerating used filter elements including the oil trapped therein. Preferably, there is no waste other than ash. Consequently, filters such as cartride filters, now completely avoid metal components. 
     Cartride filters currently use an injected end cap to seal the ends of annular filter media and a felt gasket which is adhered to the end cap with adhesive. This is a two step process which results in increased cost due to extended production time, manual handling of filter elements and questionable seal quality. Since filter elements are produced by the millions, relatively slight reductions in cost per unit can result in substantial production savings which in turn further encourage the production of “green” filter elements, thus reducing the environmental burden of filter elements. 
     SUMMARY OF THE INVENTION 
     In view of the aforementioned considerations, the present invention is directed to a filter element comprising a pleated annular filter media of flammable material having a first end and a second end. An end cap of relatively hard, resinous, flammable material is molded integral with at least one of the ends of the pleated annular filter media and an annular gasket of relatively soft resinous material, which is also flammable, is molded directly onto the relatively hard end cap so as to provide a filter element which is disposable after use by incineration. In more specific aspects of the invention, the hard resinous material is NYLON® (polyamide) or polypropylene and the gasket is rubber. 
     In alternative embodiments, the end cap is heat sealed or attached with an adhesive to one or both ends of the pleated annular filter media. 
     The present invention is also directed to a process for producing a filter element wherein the process comprises mounting a pleated annular filter media of flammable material in an injection molding machine having outlets for resinous material aligned with at least one end of the filter media. An amount of hardenable, flammable resinous material is injected into the ends of the annular pleated filter media to form end caps that seal the ends of the filter media, the hardenable resinous material having after it is injected, end surfaces which face axially with respect to the filter media. Annular deposits of flammable gasket material are then injected directly onto the end surfaces of the end caps, the gasket material forming a bond with the hardenable flammable resinous material of the end caps, whereby a filter element is provided which is disposable after use by incineration. 
     In a further aspect of the process, the hardenable resinous material is NYLON® or polypropylene and the gasket material is nitrile rubber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1A  is a side perspective view of a first embodiment of a filter element configured in accordance with the principles of the present invention; 
         FIG. 1B  is a side perspective view of a second embodiment of a filter element configured in accordance with the present invention; 
         FIG. 2  is a side view showing an annular pleated filter media disposed for alignment with a first station an injection molding machine arrangement prior to injecting relatively hard material for end caps and ejecting relatively soft material for gaskets. 
         FIG. 3  is a side view similar to  FIG. 2  showing sealing material being injected by the injection molding machine into the ends of the annular pleated filter media to form end caps; 
         FIG. 4  is a side view showing gaskets being molded by the injection molding machine onto the end caps; 
         FIG. 5  is a side view showing the completely formed filter element being ejected from its support which has been indexed through the injection molding machine assembly; 
         FIG. 6  is a perspective view of a third embodiment of an end cap and gasket arrangement according to the present invention; 
         FIG. 7  is a perspective view of a fourth embodiment of an end cap and gasket arrangement according to the present invention; 
         FIG. 8  is a side elevation of a portion of an injection molding machine for producing the end cap of  FIGS. 6 and 7 , and 
         FIG. 9  is a side elevation of an injection molding machine for molding a gasket onto the end cap of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1A , there is shown a filter element  10  configured in accordance with the principles of the present invention, wherein the filter element comprises an annular pleated filter media  12  having first and second ends  14  and  16  respectively, which ends are sealed by first and second end caps  18  an  20  respectively. The end caps  18  and  20  prevent fluid, such as for example, lubricating oil from flowing out of the first and second ends  14  and  16 , respectively of the filter media  12 . The end caps  18  and  20  are annular to leave access to a hollow core  24  within the filter media  12  so that fluid passing radially through the filter media  12  in either direction has an outlet or inlet. The end caps  18  and  20  have axially facing exposed surfaces  26  and  28  which face away from the filter media  12 . Bonded directly to the axially facing end surfaces  26  and  28  are gaskets  30  and  32 , respectively. 
     The seals  18  and  20  are made of a material such as NYLON® or polypropylene which is relatively hard and inflexible upon setting, whereas the gaskets  30  and  32  are made of a compressible and deformable elastic material, such as nitrile rubber, which deforms upon abutting a surface with which it must seal. 
       FIG. 1B  discloses a second embodiment of the invention wherein gaskets  30 ′ and  32 ′ have a smaller radial width than the gaskets  30  and  32  of  FIG. 1A . In both embodiments, the gaskets are molded directly to the end caps  18  and  20 . 
     The aforediscussed three components of the filter element  10 , i.e. the filter media  12 , the end caps  18  and  20  and the gaskets  30  and  32  are flammable. Accordingly, after use, when the filter media  12  is saturated with oil, the entire filter element  10  can be incinerated in a facility such as a steam generating power plant to destroy the residual lubricating oil so that the oil does not contaminate the soil or ground water, which is a possibility if the filter element is disposed of in a landfill. 
     Referring now to  FIGS. 2-5 , an arrangement  40  of injection molding machines has a first station  41  with first injection heads  42  for injecting hardenable sealing materials into the first ends  14  and  16  of the filter media  12  and a second station  43  with second injection heads  44  for subsequently molding gasket materials onto the end caps  18  and  20  formed by the hardenable sealing materials of the annular pleated filter media. The heads  42  each have an annular opening  50  for injecting material, such as NYLON® (polyamide) or polypropylene, into the ends  14  and  16  of the filter media  12  and the heads  44  each have an annular head  52  for molding the annular ring of gasket material, such as nitrile rubber, onto the seals. The filter media  12  is restrained within a surrounding support  54  as it is indexed through the injection molding arrangement  40 . 
     As is seen in  FIG. 3 , the heads  42  first inject material for the annular end caps  18  and  20  into the ends  14  and  16  of the filter media  12  to seal the ends of the filter media. The first molding openings  50  are configured to produce end caps  18  and  20  with the flat surfaces  26  and  28 . 
     Referring now to  FIG. 4 , after the first molding opening  50  form the end caps  18  and  20 , the second molding openings  52  eject a soft material such as nitrile rubber for the gaskets  28  and  30  onto the flat surfaces  26  and  28  of the end caps. The material forming the gaskets  30  and  32  bonds with the material of the end caps  26  and  28  so that the gaskets are adhered to the end caps to form an integral structure which is leak proof and reliable. As seen in  FIG. 5 , the molding machine  40  then ejects the now complete filter element  10  axially from the support  54  in a form ready for shipment to customers. 
     The two-shot molding process for the end caps  18  and  20  and the gaskets  30  and  32  can be done in three ways, the first being to have a first horizontal molding machine for injecting the material for the end cap  18  and a second horizontal machine, next to the first machine for ejecting the material for the gaskets  30  and  32  with the filter media  12  being indexed from one machine to the next and then ejected from the line as a complete filter element  10 . The second way is to have the material for the end caps  18  and  20  injected horizontally from a horizontal molding machine and the material for the gasket  30  and  32  ejected vertically from a vertical molding machine. The third way is to have both molding machines oriented vertically. 
     While  FIGS. 2-5  show the end caps  18  and  20  and gaskets  30  and  32  being formed simultaneously on both ends of the filter media  12 , this injection molding operation may be performed by molding end caps and gaskets on the first end  14  of the filter media 180° and then forming end caps and gaskets on the second end  16  of the filter media. 
     Alternatively, a separate set of injection molding machines can be in tandom with a first set of machines to mold end caps and gaskets on the second end of the filter media  12 . 
     The process illustrated in  FIGS. 2-5  produces complete filter elements  10  in two hands-off steps which is a faster and substantially more efficient process than the present practice of hot plate welding end caps to the ends of the filter media  12 , and then gluing gaskets thereto. 
     Referring now to  FIGS. 6-9 , a third and fourth embodiment of the invention molds the gaskets  30  and  30 ′ respectively to the end cap  18  prior to molding the end cap to the filter media  12  so as to form an integral end cap/gasket assembly  70 . The end cap/gasket assembly  70  is then fixed to the ends  14  and  16  of the filter media  12  by adhesive or heat sealing (hot plate welding) to form a “green” filter element. As with the first and second embodiments of  FIGS. 1A and 1B , the gaskets  30  and  30 ′ are preferably made of a rubber material, such as nitrile rubber, while the end caps  18  are made of a resinous material which after molding is hard. Preferable materials for the end cap  18  are polypropylene or polyamide materials. 
       FIG. 8  discloses molding of an end cap  18  wherein a material such as NYLON® (polyamide) is ejected into a die comprising a base plate  60  and a shaping die  62  from annular inlet  50 ′ in a first injection head  42 ′. The molded end cap  18  is then indexed to a second injection head  44 ′ ( FIG. 9 ) where a soft material, such as rubber or nitrile rubber, is ejected by inlets  52 ′ molded directly onto the end cap  18  in a configuration determined by a shaping die  64 . Alternatively, both the material for the end cap  18  and the material for the gaskets  30  or  30 ′ may be dispensed sequentially at the same molding machine station by moving the molding heads  42 ′ and  44 ′ or by combining the molding material inlets  50 ′ and  52 ′ in a single molding head. In still another approach, the end cap and gasket materials could by dispensed the same inlets. 
     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.