WO1997022395A1

WO1997022395A1 - Filter having magnetic components and method of manufacturing same

Info

Publication number: WO1997022395A1
Application number: PCT/US1996/020691
Authority: WO
Inventors: Clyde H. Bachand; Richard Kurtz
Original assignee: Filtertek Inc.
Priority date: 1995-12-19
Filing date: 1996-12-19
Publication date: 1997-06-26
Also published as: CA2241029A1; BR9612087A; EP0956135A1; EP0956135A4; JP2000502284A; AU1352297A

Abstract

A filter (10) comprised of a housing (12) having an inlet (14) and an outlet (16), the inlet (14) and outlet (16) defining a fluid path through the filter (10) and a filter medium (18) located in the fluid flow path. Fluid flowing in through the inlet (14) is directed through the filter medium (18). Molded directly to the surface of the filter medium is a polymer bonded magnetic material (20) positioned such that fluid flowing through the filter (10) is directed over the polymer-bonded magnetic material (20).

Description

FILTER HAVING MAGNETICCOMPONENTS AND METHODOFMANUFACTURING SAME

BACKGROUND OF THE INVENTION

This invention relates generally to fluid filters, and more particularly to fluid filters equipped with a magnetic component that acts to trap and remove contaminants from the fluid being filtered.

Fluid filters are generally capable of removing contaminants having particle sizes above a given minimum size, while smaller particles pass through the filter medium. A balance must be struck between the lower size limit of retained particles and the flow rate allowed by the filter, because as the filter medium is constructed to retain smaller particles, the speed with which fluid flows through the medium is reduced. Therefore, it is simply not possible to remove all contaminants at practical rates of flow. Metallic contaminants cause particular concern, because they may be very small, yet cause damage to the mechanism the filter is intended to protect. In, for example, an automotive engine, it is very important to remove minute metallic contaminants from the circulating lubricating oil to prevent damage to the internal engine components.

Additionally, normal engine operation continually causes the production of additional metallic contaminants. The filter medium necessary to retain such metallic contaminants would cause excessive back pressure, and therefore, these fine metallic contaminants must be removed by another means.

One alternative means of removing fine metallic particles from the fluid passing through the filter is to include a magnetic element in the filter that attracts and traps the metallic contaminants that exhibit magnetic attraction, such as iron and steel, either before or after they pass through the filter medium. Various attempts have been made to incorporate a magnetic component in a filter. Prior art magnetic filters that have included a magnetic element have generally done so by including some type of a bar magnet inside the filter assembly. For example, U.S. Patent No. 3,279,607 issued October 18, 1966 to Michaelson discloses an automotive oil filter having one or more bar magnets disposed in one or more folds of the filter material, spaced equally around the circumference of the filter housing. Similarly, U.S. Patent No. 4,501,660, issued February 26, 1985 to Hebert relates to an oil filter having a magnetized helical coil disposed in the central core of the filter assembly. An externally-attached magnetic element is disclosed by U.S. Patent No. 5,282,963, issued February 1, 1994 to Hull, et al . A magnetic element sized to fit over the end of an oil filter housing is attached to the filter housing by magnetic attraction to metallic elements of the housing and filter.

Similarly, U.S. Patent No. 5,354,462 issued October 11, 1994 to Perritt relates to a strap that fastens around the outside of an oil filter housing to hold in place magnetic elements. U.S. Patent No. 2,893,561, issued March 7, 1958 to Duzich relates to sheets of filter element material having small particles of magnetic material dispersed throughout the material or attached to the surface by impregnating the sheet with a polyvinyl acetate bonding agent.

These and other filters have inherent disadvantages, either in that they complicate the manu acturing process, cause increased back-pressure, or in that the magnetic elements are not correctly placed relative to the fluid flow path so as to maximize the fluid contact with the magnetic element, and hence the removal of magnetically-attractive contaminants.

SUMMARY OF THE INVENTION

The instant invention overcomes the problems of the prior art by strategically placing the magnetic elements directly in the fluid flow path through the filter, and they are simple to manufacture. The filter element of the invention may be enclosed within a disposable or reusable housing, or it may simply fit into a recess provided in the apparatus through which the fluid is circulated, for example an engine block. In one embodiment of the invention, the filter comprises : a) a filter housing having an inlet and outlet defining a fluid flow path; b) a filter medium located in the fluid flow path between the inlet and outlet; and c) a polymer-bonded magnetic material comprising at least one compounded magnetic filler and at least one polymeric binder, said polymer-bonded magnetic material molded onto a surface of the filter medium, such that a fluid passing through the filter is directed over the magnetic material.

Preferred embodiments include a series of "dots" of magnetic material placed on the surface of the filter medium in a pattern that covers a portion of the surface, or a grid pattern that acts to stiffen and support the filter medium, in addition to the magnetic contaminant removal function.

Alternatively, the polymer-bonded magnetic material may act as a spacer between two or more layers of filter material. In yet another alternative, the polymer-bonded magnetic material may extend through the filter medium. Numerous other possibilities exist for the size and shape of the polymer bonded magnetic material, within the scope of the present invention.

In another preferred embodiment, the filter comprises-. a) a thermoplastic filter housing having an inner wall, the inner wall of the housing impregnated with a compounded magnetic filler, and an inlet and an outlet defining a fluid flow path through the filter; and b) a filter medium disposed between the inlet and outlet such that a fluid flowing therethrough passes through the filter medium, and such that fluid is in communication with the housing inner wall.

The inner surface of the housing is rendered magnetic by such a construction, providing for a great deal of fluid contact with the magnetic elements of the filter, maximizing removal of magnetically-attractive contaminants. In yet another embodiment, a filter element comprises : a) a filter medium; b) the filter medium retained and supported by a molded thermoplastic frame impregnated with at least one compounded magnetic filler, such that the polymer-bonded magnetic material is placed in the fluid flow path. In one preferred embodiment, the filter element comprises : a) a substantially cone-shaped frame, having an open base and a vertex; b) a filter medium supported by a plurality of ribs connecting the vertex and the open base; and c) a polymer-bonded magnetic cap over-molded to the vertex of the cone-shaped frame.

Other embodiments of the filter element include a flat, disk-shaped element, a cylinder shape, or any other shape required by a given application.

In another preferred embodiment, the filter includes a magnetic "anti-drain-back valve" to prevent the fluid being filtered from draining back out of the filter when the fluid is no longer under pressure, i.e. "reverse-flow. " The anti- drain-back valve consists of a flap constructed from neoprene, or another suitable material, that covers the filter inlet on the inside of the filter housing. When the fluid is under pressure, i.e., being forced through the filter, the flap is lifted by the force exerted by the fluid, allowing the fluid to flow into the filter. When the pressure is removed, the flap seals the inlet from the inside of the housing, preventing reverse-flow of the unfiltered fluid. The flap is impregnated with a compounded magnetic filler, rendering the flap magnetic. As the fluid flows into the filter it is directed over the magnetic flap, thereby removing magnetically-attractive contaminants from the fluid. The method of manufacturing the filters of the claimed invention comprises using insert injection molding techniques and equipment to deposit molten thermoplastic resin material impregnated with at least one compounded magnetic filler on the filter medium in a designated pattern or to create the thermoplastic resin frame, cap or other magnetic- impregnated element. The magnetic filler may then be magnetized and magnetically oriented during the molding process, before or after the thermoplastic resin has set, according to methods well-known to those in the art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a filter having polymer- bonded magnetic material molded to the surface of the filter medium.

FIG. 2 is a plan view of a transmission filter medium and grid framework comprising a polymer-bonded magnetic material. FIG. 2A is cross-section of the transmission filter medium and grid framework of FIG. 2 in a folded, operational relationship.

FIG. 3 is a cross-sectional view of a filter having a thermoplastic housing, the wall of which is impregnated with a compounded magnetic filler.

FIG. 4 is a cross-sectional view of a filter having a housing, the inner wall of which is coated with a polymer-bonded magnetic material. FIG. 5 is cross-sectional view of a cone-shaped filter element having a magnetic frame.

FIG. 6 is a cross-sectional view of a cone-shaped filter element having a magnetic cap affixed to the frame. FIG. 7 is a plan view of a disk-shaped filter element with a magnetic fra e. FIG. 8 is a plan view of a disk-shaped filter element having a magnetic cap affixed to the frame.

FIG. 9 is a cross-sectional view of a filter including an anti-drain-back valve. FIG. 10 is a plan view of a cylindrical filter element having a magnetic frame. DETAILED DESCRIPTION OF THE DRAWINGS

AND PREFERRED EMBODIMENTS OF THE INVENTION

Figures 1-10 show ten different embodiments of filters and/or filter elements embodying the present invention. Referring to Fig. 1, the filter 10 of one preferred embodiment of the invention is comprised of a housing 12, having an inlet 14 and an outlet 16, the inlet 14 and outlet 16 defining a fluid flow path through the filter 10, and a filter medium 18 located in the fluid flow path.

Fluid flowing in through the inlet 14 is directed through the filter medium 18. Molded directly to the surface of the filter medium 18 is a polymer-bonded magnetic material 20 positioned such that a fluid flowing through the filter 10 is directed over the polymer- bonded magnetic material 20. In the embodiment depicted in Fig. 1, the polymer-bonded magnetic material 20 is in the shape of a circular deposit, although other forms are contemplated within the scope of the invention, including a series of such deposits spaced at intervals across the surface of the filter medium 18.

Referring to Figs. 2 and 2A, a second preferred embodiment of the invention is shown, wherein the filter is for an automotive transmission, such as shown in U.S. Patent No. 4,828,694, incorporated herein by reference. The transmission filter includes a housing (not shown) and a filter medium 17 which folds to form an envelope 19. An inlet hole 21 is cut in the filter medium 17, which is adjacent an inlet in the housing (not shown) . Placed within the envelope 19 of the filter medium 17 is a polymer-bonded magnetic material 23 in the shape of a grid pattern 23 that acts to support the filter medium 17 and prevent the collapse of the envelope 19. In this embodiment, the grid 23 will also attract and trap magnetically-attractive contaminants as the fluid flowing through the filter passes over the polymer- bonded magnetic material.

Referring to Fig. 3, a third embodiment of the filter of the invention is shown, wherein the filter 30 includes a housing 32 with an inner wall 33, an inlet 34, and an outlet 36, the inlet 34 and the outlet 36 defining a fluid flow path through the filter 30, such that a fluid flowing through the filter 30 is in communication with the inner wall 33, and a filter medium 38 located in the fluid flow path. The inner wall 33 of the housing 32 is impregnated with a compounded magnetic filler, rendering the inner wall 33 magnetic. An alternative form of this embodiment is depicted in Fig. 4, wherein the filter 40 includes a housing 42 with an inner wall 43, an inlet 44 and an outlet 46 defining a fluid flow path through the housing 42, and a filter medium 48 located in the fluid flow path. The inner wall 43 is coated with a polymer-bonded magnetic material 45. Fluid flowing through the filter 40 is in communication with the inner wall 43 and, thus, with the polymer-bonded magnetic material 45 coating the inner wall 43.

Referring to Fig. 5, a fifth embodiment of the filter 50 includes a cone-shaped frame 52, having a base ring 53, a vertex 54 and ribs 55 connecting the base ring 53 with the vertex 54 and supporting a filter medium 56. In this embodiment, the frame 52 is constructed from a molded thermoplastic resin impregnated with a compounded magnetic filler. The fluid passing through the filter medium 56 is directed over the frame 52, and any magnetically-attractive contaminants are removed by contact with the magnetic filler- impregnated frame.

Referring to Fig. 6, which depicts a sixth embodiment of the invention, the frame 62 is not impregnated with a magnetic filler, but instead, a cap 64 constructed from a polymer-bonded magnetic material is affixed to the vertex 66 of the frame 62 placing the cap 64 in the fluid flow path through the filter. Fluid flowing through the filter passes over the cap 64, thereby removing magnetically-attractive contaminants from the filter.

Referring to Fig. 7, depicted is a seventh embodiment of the present invention comprising a filter element 70, generally in the shape of a disc, having a ring- shaped frame 72, a hub 73 and ribs 74 connecting the frame 72 with the hub 73. A filter medium 76 is supported by the frame 72, the hub 73, and the ribs 74. At least a portion of the frame 72, ribs 73 and/or hub 74 are constructed from a molded thermoplastic resin impregnated with a compounded magnetic filler, rendering that portion of the structure magnetic.

Fluid passing through the filter is directed over the frame 72, ribs 73 and/or hub 74, thereby trapping and retaining magnetically-attractive contaminants. An alternative is depicted in Fig. 8, where the frame 82 is not impregnated with the magnetic compound, but a cap 84 molded to the hub 86 is impregnated with a compounded magnetic filler. Fluid flowing through the filter is directed over the magnetic cap 86, removing magnetically-attractive contaminants from the fluid as the fluid passes over the cap 86. Fig. 9 depicts a ninth embodiment of the invention, wherein the filter 90 incorporates an anti-drain-back valve 92. The anti-drain-back valve 92 comprises a polymeric flap impregnated with a compounded magnetic filler, positioned so as to cover the inner opening of the filter inlet 95. As the fluid enters the inlet 95, the fluid passes over the magnetic- impregnated polymeric flap 92, thus removing and retaining magnetically-attractive contaminants.

Fig. 10 depicts a tenth embodiment of the invention, wherein the filter 100 includes a cylindrical frame 102, the frame 102 defining an inlet 104 and an outlet 106. The frame 102 is molded from a polymeric material impregnated with a compounded magnetic filler. Fluid passing through the filter 100 contacts the frame 102, and any magnetically-attractive contaminants are removed from the fluid by contact with the magnetic filler-impregnated frame 102.

The filter medium may comprise any type of known filter medium, such as woven materials and non-woven materials. Examples of suitable materials include polyester felt; phenolic resin-impregnated polyester felt; a woven screen made from nylon, polyester, or polypropylene; filter membrane material; paper; and phenolic resin-impregnated paper. The polymer-bonded magnetic materials used in the invention consist of a compounded magnetic filler and a polymeric binder. Exemplary magnetic materials include barium ferrite, strontium ferrite, isotropic neodymiu -iron-boron, anisotropic neodymium-iron-boron, samarium-cobalt and hybrid materials formed from mixtures of the foregoing. Exemplary polymeric binders include Nylon 6, Nylon 4/6, Nylon 6/6, Nylon 6/10, Nylon 12, polyphenylene sulfide, polypropylene, polyethylene and nitrile rubber. Although the invention has been described by reference to several illustrative embodiments, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not intended to be limited to the details disclosed herein but is to be accorded the full scope of the claims set forth below.

Claims

We claim :

1. A filter having magnetic components, comprising: a) a filter housing, having an inlet and outlet defining a fluid flow path; b) a filter medium located in the fluid flow path between the inlet and outlet; and c) a polymer-bonded magnetic material comprising at least one compounded magnetic filler and at least one polymeric binder, said polymer-bonded magnetic material molded onto a surface of the filter medium, such that a fluid passing through the filter is directed over the magnetic material.

2 The filter of claim 1 wherein the filter is an oil filter.

3. The filter of claim 1 wherein the filter is an automotive transmission filter

4. The filter of claim 1, wherein the polymer-bonded magnetic material is molded onto a surface of the filter medium m a grid pattern.

5. The filter of claim 1, wherein the polymer-bonded magnetic material is molded onto the filter medium to form discrete deposits of polymer-bonded magnetic material spaced at intervals across a surface of the filter medium.

6 The filter of claim 1 wherein the filter medium comprises a woven material

7. The filter of claim 1 wherein the filter medium comprises a non-woven material .

8. The filter of claim 1 wherein the filter medium comprises at least one of the following: polyester felt, phenolic resin-impregnated polyester felt, woven nylon screen, woven polyester screen, woven polypropylene screen, filter membrane, paper and phenolic resin-impregnated paper.

9. The filter of claim 1 wherein the polymeric binder comprises at least one of the following: Nylon 6, Nylon 4/6, Nylon 6/6, Nylon 6/10, Nylon 12, polyphenylene sulfide, polypropylene, polyethylene and nitrile rubber.

10. The filter of claim 1, wherein the compounded magnetic filler comprises at least one of the following: barium ferrite, strontium ferrite, isotropic neodymium-iron-boron, anisotropic neodymium-iron-boron, samarium-cobalt and hybrids thereof.

11. A filter having a valve mechanism to prevent reverse-flow of a fluid passing through the filter, wherein said valve is constructed of a polymer- bonded magnetic material.

12. A filter having magnetic components comprising: a) a filter housing having an inlet and an outlet defining a fluid flow path through the housing; b) a filter medium supported by a frame, wherein the filter medium is located in the fluid flow path between said inlet and outlet; and c) wherein at least a portion of said frame is molded from a thermoplastic resin impregnated with a compounded magnetic filler, located such that a fluid passing through the filter medium passes over the magnetic portion of the frame.

13. The filter of claim 12, wherein said magnetic filler comprises at least one of the following: barium ferrite, strontium ferrite, isotropic neodymium- iron-boron, anisotropic neodymium-iron-boron, samarium-cobalt and hybrids thereof.

14. A filter having magnetic components, comprising: a) a thermoplastic filter housing having a wall, said wall having magnetic properties, and an inlet and an outlet defining a fluid flow path through the filter; and b) a filter medium disposed between the inlet and outlet such that a fluid flowing therethrough passes through the filter medium, and such that the fluid is in communication with the wall, to thereby remove magnetically-attractive contaminants from the fluid.

15. The filter of claim 14 wherein the wall is impregnated with a compounded magnetic filler

16. The filter of claim 15 wherein an inner surface of the wall is coated with a polymer-bonded magnetic material .

17. A filter element having magnetic properties, comprising: a) a filter medium; b) said filter medium retained and supported by a molded thermoplastic frame, at least a portion of said frame impregnated with at least one compounded magnetic filler and said filter medium defining a fluid flow path through the filter medium such that a fluid flowing through the filter element is directed over the frame.

18. The filter element of claim 17 wherein a) said frame is substantially cone-shaped, having an open base and a yertex; b) said filter medium is supported by a plurality of ribs connecting the vertex and the open base.

19. A filter element having magnetic properties, comprising: a) a filter medium; b) said filter medium retained and supported by a molded thermoplastic frame, said frame and said filter medium defining a fluid flow path through the filter medium; and c) a polymer-bonded magnetic material comprising at least one compounded magnetic filler and at least one polymeric binder, said polymer-bonded magnetic material attached to said frame, located such that the polymer-bonded magnetic material is placed in said fluid flow path.

20. The filter element of claim 19 wherein a) said frame is substantially cone-shaped, having an open base and a vertex; b) said filter medium is supported by a plurality of ribs connecting the vertex and the open base; and c) said polymer-bonded magnetic material is a cap over-molded to the vertex of the cone-shaped frame.

21. The filter element of claim 17, wherein said filter element is in the shape of a flat disk.

22. The filter element of claim 19, wherein said filter element is in the shape of a flat disk.

23. A method of manufacturing a filter having magnetic components, comprising the steps of: a) enclosing a filter medium having a surface, in an injection mold having mold cavities that correspond to a desired pattern; b) injecting a molten thermoplastic resin into the injection mold, said thermoplastic resin impregnated with a compounded magnetic filler; c) depositing said thermoplastic resin directly on the surface of the filter medium in the desired pattern.

24. The method of claim 23 further comprising the steps of magnetically orienting the polymer-bonded magnetic material during the injection molding process by application of a magnetic field to the mold cavities of the injection mold containing the filter medium.

25. The method of claim 24, further comprising the steps of: a) providing electromagnets in communication with the mold cavities of the injection mold; and b) passing an electrical current through the electromagnets after injecting the thermoplastic resin into the mold, to thereby magnetize and magnetically orient the compounded magnetic filler.

26. The method of claim 23 further comprising the steps of magnetically-orienting the polymer-bonded magnetic material after molding by subjecting the filter medium carrying the polymer-bonded magnetic material to a magnetic field after the injection molding is completed.

27. A method of removing magnetically-attractive contaminants from a flowing fluid comprising the steps of :

(a) passing the flowing fluid through a filter comprising a filter medium having polymer-bonded magnetic material molded onto a surface of the filter medium, said polymer-bonded magnetic material comprising at least one compounded magnetic filler and at least one polymeric binder, the filter medium located in the fluid flow path; and

(b) the magnetic material attracting and retaining said magnetically-attractive contaminants within the filter.