Patent Application
20060196823
This invention relates to a method and apparatus for adhering a filter media to a plastic member such as a fuel filter diverter.
Filter assemblies include a filter media to filter debris from a fluid. Filter medias are often bonded to a structural component by using a heat curable adhesive material such as plastisol. In some filter applications, such as automotive fuel filters, a heat sensitive filter media is used. One typical heat sensitive filter media is constructed from polyester, which tends to degrade in structural integrity and performance when it has been subjected to heat of 325° F. or more. Plastisol is typically cured by heating the plastisol along with the fuel filter diverter and filter media in a relatively long oven, which exposes the heat sensitive filter media to higher than desired temperatures.
Hot melt glues and epoxies can be used to secure the heat sensitive filter media to the fuel filter diverter to obviate the need for an oven. It is desirable to utilize a plastic fuel filter diverter for various reasons. However, current hot melt glues and epoxies that are compatible with suitable plastics for fuel filter diverters are not able to withstand the chemicals that are typically present in fuel filter applications.
Therefore, what is needed is an apparatus and method of securing a heat sensitive filter media to a plastic structure, such as a fuel filter diverter, without damaging the heat sensitive media.
The present invention provides a filter assembly including a plastic base and a metal member secured to the plastic base. In the example of a fuel filter assembly, the plastic base may be provided by a fuel filter diverter, which may also include an integrated center tube. A filter media is secured to the metal member with a heat-curable adhesive material, such as plastisol. The metal member acts as an end disc for the filter media.
The plastic base may be over-molded around the metal member, or the metal member may be secured to the plastic base subsequent to its forming.
The heat-curable adhesive material is dispensed in a desired manner. For example, the heat-curable adhesive material may be dispensed directly onto the metal member. The filter media is arranged on the metal member with the heat-curable adhesive material arranged between the filter media and metal member.
Induction heating is used to generate localized heat in the metal member to heat and cure the heat-curable adhesive material. In this manner, the filter media, which may include a heat sensitive polyester, is not subjected to damaging levels of heat.
Accordingly, the present invention provides a method and apparatus that secures a heat sensitive filter media to a plastic structure without damaging the filter media.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A filter assembly 10, and more specifically a fuel filter assembly, is shown in
In the example shown, the diverter 20 is constructed from a plastic material. A center tube 22 extends from the diverter 20 toward the outlet tube 16. The center tube 22 is integrally formed with a base 29 of the diverter 20. A filter media 24 having a central opening 23 is supported by the diverter 20 with the center tube 22 arranged within the central opening 23.
The housing 12 includes a case 26 and a cover 28 that is secured to the case 26 in a known manner. A first side 30 on the base 29 of the diverter 20 is sealed against a bottom of the case 26 to fluidly separate flow through the inlet and return tubes 14 and 18. The diverter 20 is typically sealed against the case 26 with a load exerted on the diverter 20 by the cover 28. An opening 31 in the diverter 20 allows flow of fluid to the return tube 18.
The filter media 24 is sealed between a second side 32 on the base 29 and the cover 28 using an adhesive material 38, typically plastisol. In this manner, fluid is prevented from circumventing the filter media 24. In fuel filter applications, the filter media 24 is typically constructed from a material that includes polyester, which is heat sensitive. The filter media 24 may be constructed from primarily polyester, or the filter media 24 may be constructed from a cellulose substrate having a polyester layer. The integrity and performance of polyester typically degrades when exposed to temperatures of approximately 325° F. or greater.
Adhesive material such as plastisol cannot be cured using conventional ovens when used in conjunction with polyester-containing filter media since the polyester will be subject to temperatures of 325° F. or greater. To this end, the inventive filter assembly 10 incorporates a structure that is suitable for use with an inductive heating system. An inductive heating system will not expose the polyester-containing filter media to high temperatures. A metal member or metal disc 36 is utilized adjacent to the adhesive material 38. The metal disc 36 is excited by the inductive heating system thereby generating localized heat to cure the adhesive material 38.
In a first example embodiment, the diverter 20 is molded over a metal disc 36, which is best shown in
In another example embodiment, a metal disc 46 includes multiple holes 48 and multiple dimples 50, which act as stand-offs. The metal disc 46 includes an aperture 52 for accommodating the center tube 22. Adhesive material 38 is arranged between the second side 32 and the metal disc 46. The dimples 50 space the metal disc 46 from the second side 32 providing a cavity 54 filled with the adhesive material 38. Adhesive material 38 is also arranged on the metal disc 46 opposite the cavity 54 and onto which an end of the filter media 24 is embedded. An annular lip 56 of the base 29 contains the adhesive material 38 in a desired area and locates the filter media 24 in a desired manner.
An inductive heating system 58 is schematically shown in
An end of the filter media 24 is embedded into the adhesive material 38 adjacent to the metal disc 36 or 46, as indicated at block 70. The metal disc 36 or 46 is inductively heated, as indicated at block 72, to cure the adhesive material 38.
Referring to
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For example, the metal discs 36 and 46 may be different shapes than shown. For that reason, the following claims should be studied to determine the true scope and content of this invention.
