Background of the Invention There has been, and is, a need within for example, the automotive industry, to reduce metal abrasion which occurs between moving engine components, which are conventionally lubricated with "filtered" motor oil. In the main, this abrasion is caused by ferrous (iron) particles or by-products produced by the continuous contact between moving engine parts during normal use. It has been well established that the metal-on- metal wear occurring within an internal combustion engine is related to the cleanliness of oil which lubricates the moving parts and the time limited additives which break down through the combustion of heat, as well as through oil contamination from the introduction of by-products.

The most common method of removing contamination from oil circuiated through a conventional internal combustion engine, is the utilization of an oil filter. Generally oil filters act by passing contaminated oil to the core of the filter and through a filtration media, generally paper, towards the outer internal surface of the filter housing.

Following contact with the internal surface of the filter housing, the oil, filtered to remove major contaminants, is directed upwardly to the top of the filter housing, from whence it passes back into the system.

Research has proven that "throw-away" conventional engine filters are efficient only to remove contaminants where they are of a size of 25 microns or greater, not withstanding whether these contaminants are ferrous or non ferrous. it is, however, the "ferrous" particles, that the present invention addresses and more particularly to those particles less than 25 microns in size.

Conventional oil changes fail to clear out the ferrous particles. When the oil is drained, the ferrous particles cling to the motor interior parts or collect on the oil pan.

When new oil is added it, in turn, picks up the ferrous particles and continues the wear cycle. Previously, the only way to break this cycle was to flush the engine on every oil change.

An investigation into the prior art has shown that considerable development in the use of magnets and generated magnetic fields has been undertaken, and as a result, numerous patents have been issued on structures that utilize previously well- known magnetic principles to assist in the removal or extraction of ferrous (iron) by- products produced by the continuous wearing of moving internal combustion engine parts, during normal vehicle operation.

U.S. Patents 5,273,193 and 5,085, 768 both to Murakami, disclose the use of a magnet to collect "splatter" generated in a tank during a welding process. The magnets effectively prevent metal particles from passing from the tank to, for example, a fuel pump.

The systems described by Murakami are not, however, adaptable for use in conjunction with disposable oil filters, and are concerned primarily with the incorporation of magnets within a filter housing. Magnets used in this way are high maintenance and generate increased costs, in view of the considerable time required to collect and clean them.

A prior system for use with disposable filters is disclosed in U.S. Patent 5,354,462 issued to Perritt in 1994. The magnetic filter is in the form of a strap and is mountable about an oil filter by means of a fastener or by magnetic attraction. The filter includes bar magnets spaced along the strap. The disclosed system is very expensive to manufacture because it requires the use of relatively high strength bar magnets.

Further, because of the vibration generated during engine operation, the straps tend to slip off the filter casing.

Summarv of the Invention The present invention provides a magnetic filter that is inexpensive, but effective to remove ferrous materials from a flowing or static fluid body. The invention provides a simple, reusable system that can be quickly and easily attached to any structure containing fluid to be filtered such as, for example, a conventional "throw away" automobile oil filter. Further, the invention provides a magnetic filter that can be attached to a housing and is resistant to removal by the effects of vibration.

Accordingly, a broad aspect of the present invention provides a reusable apparatus for the extraction of ferrous particles from a body of fluid within a housing, said apparatus being located adjacent said body of fluid in direct contact with said housing, but out of contact with said body of fluid, wherein said apparatus comprises a plurality of magnets incorporated within a sheet of resilient material, said sheet of resilient material being adapted to be mounted with its inner surface applied adjacent the outer surface of said housing and having applied to the inner surface a reuseable adhesive.

In accordance with another broad aspect of the present invention, there is provided a reusable apparatus for the extraction of ferrous particles from a body of fluid within a housing, said apparatus being located adjacent said body of fluid in direct contact with said housing, but out of contact with said body of fluid, wherein said

apparatus comprises at least one magnet secured in a cavity formed in the surface of a sheet of resilient material, said sheet of resilient material being adapted to be mounted with its inner surface applied adjacent the outer surface of said housing and having secured to the inner surface a tear resistant material.

In accordance with yet another broad aspect of the present invention, there is provided an apparatus for the extraction of ferrous material from a body of fluid within a housing, the housing having a diameter, said apparatus being located adjacent said body of fluid in direct contact with said housing, but out of contact with said body of fluid, wherein said apparatus comprises a plurality of magnets incorporated within a sheet of resilient material, the magnets each being selected such that their effective field of magnetism penetrates into the housing a distance equal to about 45 - 50% of the housing diameter.

Brief Description of the Drawings The invention will now be described, by way of example only, reference being made to the accompanying drawings in which: Figure 1 is a plan view of a first embodiment of the present invention, which utilizes an array of disk magnets, incorporated within a thin flexible matrix; Figure 2 is a sectional view along line 2-2 of Figure 1; Figure 3 is a plan view of a second embodiment of the present invention wherein the magnetic elements are in the form of bar magnets; Figure 4 is a side elevation view of the embodiment according to Figure 3;

Figure 5 is a plan view of a third embodiment of the present invention which utilizes a selected spacial arrangement of magnets; Figure 6 is a perspective view of another magnetic filter according to the present invention utilizing a sheet induced to have magnetic properties at selected points, the sheet being mounted on a structure; and Figure 7 is a sectional view through another magnetic filter according to the present invention.

Detailed Description of the Invention The device of the present invention may be adapted for use in any application where ferrous by-products are to be separated from a contaminated flow or body of fluid. While the device has been described hereinafter for use in conjunction with the conventional "throw away" automotive oil filter previously discussed, it also has application, for example, in conjunction with pipes having fluid passing therethrough or with filters for hydraulic systems.

The magnetic filter apparatus operates on the principle that a moderate magnetic field operating within the vicinity of the oil filter, will collect any size of ferrous material which has passed through the filter paper system forming the major component of the filter. By collecting the material and retaining the material within the oil filter, the continued circulation of the suspended ferrous particles in the filtered oil will be prevented, thus reducing subsequent metal-on-metal wear caused by the circulation of ferrous particles and ultimately offering extended engine life.

As will be appreciated from the following description of the various embodiments of the present invention, the filter apparatus according to the invention is designed to conveniently attach itself to the housing of any conventional oil filter for servicing motor

vehicle engines and can also be applied to industrial oil filter systems. Preferably, the device according to the invention is fitted to the side of the motor filter and is maintained in position on the metallic skin of the filter housing through magnetic attraction. It is to be understood that the device can be fitted with fasteners at its ends, such as, for example, snap attachments, to permit the fastening of the device to housings not made of ferrous material. Alternately, or in addition, adhesives can be used to fasten the device to a housing structure.

Referring to Figures 1 and 2, a magnetic filter device according to the present invention is shown wherein a relatively high density magnetic field is obtained by utilizing a number of strong disk magnets 10 suspended in a flexible sheet 11 formed of, for example, plastic, rubber or vinyl composition. To permit use of the filter device in an engine environment in a climate where the temperatures fall below freezing and operation of an engine results in large temperature fluctuations at the oil filter, the magnets are preferably formed of a material which is resistant to performance degradation in the temperature range of -40°F to 240"F and which are resistant to demagnetization by the effects of vibration. Suitable magnets for such environments are, for example, magnets formed of ceramic material or iron boron.

The magnet filter device can be wrapped around the outer circumference of the oil filter or other structure on which it is to be used, and as indicated above, be maintained in position through magnetic attraction. Since oil filters can vary in size, the size of the individual magnets 10, the number of magnets used, the strength of the magnets, and the spacing between magnets will be selected to suit specific applications.

It will be accepted that the final design parameters of the product would be dependent on the application and field of use. As an example, on the basis of automobile oil filters currently available, a disk magnet having a radius of under one

quarter of an inch is useful. As an example, a magnet for use with automobile oil filters has a magnetic intensity of preferably about 3,800 Gauss.

Figures 3 and 4 show another high density magnetic field filter which is generated in this case by the utilization of a number of equidistantly spaced bar magnets 12, again preferably of ceramic material or iron boron, which are embedded in or mounted on a flexible rectangular sheet 13 similar to that disclosed with regard to the embodiments of Figures 1 and 2. Again, the strength of the magnetic field can be augmented or decreased by adjustment of the number of magnets utilized and the individual strength of the magnets. This embodiment, however, differs from the previously described arrangement in that, unlike the disk system, the overall vertical pattern of the magnetic field cannot be readily varied.

As will be appreciated, this device is also designed to be applied to the outer surface of a conventional disposable oil filter or other structure containing a fluid to be filtered.

A further embodiment of the invention is shown in Figures 5 and 6. The arrangement shown optimizes the positioning of the magnets on the flexible sheet to maximize the magnetic field applied on the body of fluid to be filtered. This is achieved by substantially eliminating the formation of fields of demagnetization between the magnets.

A field of demagnetization will be formed where the magnetic fields induced by adjacent magnets overlap. In a field of demagnetization, the magnetic field is diminished as compared to an area in the field which is not overlapping. The magnetic filter of this embodiment uses a plurality of magnets 110 which can be disk magnets as shown or other forms, for example bar magnets. The magnets each have an intensity of, for example, at least about 500 Gauss, and preferably between about 1,500 to 5,000 Gauss. Magnets 110 are mounted in a flexible sheet 111 formed of any suitable

material. Magnets 110 are mounted on sheet 111 in any suitable way such as, for example, by use of adhesives to secure the magnets in cavities formed in the sheet or by injection molding of the sheet about the magnets.

In the preferred embodiment, the device is used on a housing containing fluid to be filtered, the magnets are each selected such that their effective field of magnetism penetrates to a distance of 1 - 60% and preferably 45 - 50% of the longest distance across the cross section of the housing (i.e. the diameter of the housing, where the housing has a circular cross section). The effective field of magnetism is defined as that field, when penetrating the housing and fluid at normal operating conditions, which is effective to attract ferrous particles having a size of less than 25 microns. Preferably, magnets 110 are closely positioned on sheet 111 but are spaced relative to one another to reduce the effects of demagnetization therebetween. In one embodiment, magnets 110 are positioned in a plurality of substantially parallel rows. The magnets in each row are aligned to define an axis. In Figure 5, three rows are shown defining axis 120a, 120b, 120c. The magnets in each row, for example row 120b, are each spaced at an angle a from the axis of the adjacent row, for example 120a and 120c. The value of a is between about 30O - 60° and preferably a is substantially 45". The spacing between magnets in the same row and between alternate rows is selected to be between about 30% to 70% of the longest distance across the cross section of the housing and preferably between about 35% to 50% of the longest distance across the cross section of the housing.

In a preferred embodiment of simplified construction as shown in Figure 6, the sheet 211 of the filtering apparatus is formed of a material, such as for example, a strontium ferrite powder-filled polymer, which is flexible and which can be magnetized at selected points 210 along the polymer sheet. In this embodiment, the problems associated with the mounting of the magnets on the sheet are avoided. The points to be magnetized can spaced from one another a suitable distance to minimize the formation of fields of demagnetization, as discussed with reference to Figure 5.

The filter magnet device of the present invention can be mounted on a structure for use in filtering fluid within the structure in any suitable way, such as by fasteners or by magnetic attraction. To facilitate installation, the filter of the preferred embodiment can be mounted by magnetic attraction.

Where the filter is mounted by fasteners or magnetic attraction and is located in an environment subject to vibration, the sheet may become dislodged from the housing to which it is attached. To avoid the filter from becoming dislodged by the effects of vibration, the flexible sheets 11, 13 and 111 of Figures 1 to 5 are preferably formed of a closed cell foam, such as for example an EPDM rubber foam.

In another embodiment, the positioning of the filter on a structure is maintained by treating the surface of the sheet with a slip resistant material. Preferably, the slip resistant material is a reusable adhesive, as opposed to a permanent adhesive, which is useful to form a bond between parts but which bond can be released at any time by application of force to separate the parts, the adhesive retaining its adhesive qualities over time and after formation and release of a bond. A suitable reusable adhesive is for example, a pressure sensitive adhesive composition, for example, NylobondTM or an acrylic based polymer PSC 5001 TM available from Polymer Science Corporation.

Pressure sensitive adhesives are those know to adhere a first part, to which the adhesive has been applied, to a second part by application of a light pressure but which is releasable to remove the first surface from the second surface by application of a force moving the first part away from the second part, in particular, by a peeling action.

The slip resistant material can be applied, by any suitable method, to the inner facing surface of any magnetic filter sheet, such as those shown in Figures 1 to 5. The slip resistant material can be used in combination with other securing means such as fasteners or magnetic attraction or, alternately, can be used as the primary means of securing a magnetic filter to a structure. Referring for example to Figure 6, treatment of the inner surface 222 of the flexible sheet 211 with a pressure sensitive adhesive 223 allows the sheet to be applied to a structure 224 and to resist slippage along the

surface of the structure. When desired, however, the sheet can be removed from the structure by a peeling action. The slip resistant material can alternately be a permanent adhesive. However, use of such a material can limit the reusability of the magnetic filter.

In another embodiment, shown in Figure 7, the magnetic filter is reinforced by providing a thin layer of substantially tear resistant material 150 over the surface of flexible sheet 111 over which is applied the slip resistant material 123. The tear resistant material can be, for example, fibreglass, polyester or nylon webbing. A preferred tear resistant material is the polyester fabric known as Reemay(E) which is resistant to degradation by many of the chemicals and the operating temperatures associated with automotive environments and to degradation by large temperature fluctuations. The webbing acts to prevent the matrix from tearing and/or the magnets 110 from being torn out of the cavities 151 in sheet 111 into which they are secured, for example during removal of the sheet from the housing onto which it is magnetically adhered. The tear resistant material is secured by unreleasable means, for example by a permanent adhesive or by heat welding, to the sheet 111.

Another layer of material 152, such as a foil or, preferably, a polycarbonate film, for example a LexanB film available from General Electric Company, can be applied to the opposite side of the sheet 111 for enhancing the appearance of and strengthening the device. A polycarbonate film is resistant to most chemicals associated with automotive environments, is capable of withstanding large temperature fluctuations with compromising its properties and will readily accept and retain printing inks. Material 152 is secured to sheet 111 by unreleasable means such as, for example, a permanent adhesive or heat welding.

In operation, as will be appreciated from the foregoing, ferrous particles normally suspended in the oil flowing through the filter are magnetically drawn to the internal side

or surface of the filter housing. The particles are held in this position and prevented from circulating with the oil.

As previously mentioned, the inventive structure described herein can be utilized in many other industrial applications, where ferrous particles suspended in a moving or stationary body of fluid have to be extracted. It will also be appreciated that while in the embodiments described, permanent or natural magnetic materials have been utilized, if higher magnetic strengths are required then conventional electro-magnets can be substituted.

The invention is therefore not intended to be restricted to the embodiments or applications described herein, but limited only by the scope of the appended claims.