Patent Abstract:
A magnet assembly includes a ring shaped magnet having a face with an inner surface that is removably attachable to a ferrous metal housing of a fluid filter. The face has a plurality of circumferentially spaced pairs of poles that concentrate the magnetic strength of the magnet on the face and form magnetic loops in the filter housing to cause any ferrous metal particles in the fluid being circulated through the filter housing to be trapped against interior walls of the filter housing.

Full Description:
FIELD OF THE INVENTION 
     This invention relates to a magnet assembly for removing ferrous metal particles from fluids including particularly engine oil and hydraulic fluids. 
     BACKGROUND OF THE INVENTION 
     There are numerous filters on the market that are effective in keeping lubricating fluids such as engine oil for gasoline and diesel engines and hydraulic fluids used to drive various machinery free of most contaminants. However, many harmful ferrous metal particles of minute size are produced through normal wear that are not effectively removed by most filters. When the minute ferrous metal particles are allowed to flow freely through a lubrication or hydraulic fluid system, they will actually create more wear and more harmful ferrous metal particles. 
     In the past, numerous attempts have been made to use magnetic devices of various types to trap ferrous metal particles in a filter with varying degrees of success. However, there continues to be a need for a magnet assembly that is more effective in removing minute ferrous metal particles circulating through lubricating or hydraulic fluid filters. 
     SUMMARY OF THE INVENTION 
     The magnet assembly of the present invention is capable of removing virtually all minute ferrous metal particles that might otherwise freely circulate through lubricating or hydraulic fluid systems. 
     In accordance with one aspect of the invention, the magnet assembly includes a high strength disc shaped magnet that concentrates the magnetic strength on the face of the magnet giving the magnet a much higher magnetic face strength. 
     In accordance with another aspect of the invention, the high magnetic face strength of the magnet of the present invention forms magnetic loops in the ferrous metal walls of a fluid filter housing to cause the filter walls to collect and hold any ferrous metal particles in the fluid being circulated through the filter. 
     In accordance with another aspect of the invention, the inner surface of the magnet face has a conical taper that generally conforms to a rounded concave contour of the outer end wall of most canister type filter housings. 
     In accordance with another aspect of the invention, the magnet has a center hole to provide an opening for receipt of a nut on the outer end of some filters. 
     In accordance with another aspect of the invention, the magnet is contained within a cup-shaped plastic housing that provides some protection against breakage in the event that the magnet assembly is inadvertently dropped against a hard surface. Also, the housing covers the outer end of the magnet center hole preventing debris from entering the magnet assembly from the outside. 
     In accordance with another aspect of the invention, a ferrous metal disc may be placed in close proximity to the outer surface of the magnet face to aid in focusing the magnetic flux on the magnet face. 
     In accordance with another aspect of the invention, a friction pad may be interposed between the magnet assembly and outer end wall of the filter housing to prevent the magnet assembly from sliding sideways relative to the filter housing when the filter is mounted horizontally and is subject to high vibration while still permitting the magnet assembly to be peeled off the filter and reused over and over whenever the fluid is changed and the filter is replaced. 
     These and other objects, advantages, features and aspects of the present invention will become apparent as the following description proceeds. 
     To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but several of the various ways in which the principles of the invention may be employed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the annexed drawings: 
     FIG. 1 is a schematic perspective view partially broken away showing one form of magnet assembly in accordance with the present invention attached to the outer end wall of a conventional canister type oil filter; 
     FIG. 2 is a schematic perspective view of the magnet assembly of FIG. 1; 
     FIG. 3 is a vertical section through the magnet assembly of FIG. 2, taken generally along the plane of the line  3 — 3  thereof; 
     FIG. 4 is a top plan view of a flux concentration disc that is attached to the outer side of the magnet face; 
     FIG. 5 is a side elevation view of the flux concentration disc of FIG. 4; 
     FIG. 6 is a schematic perspective view showing how the concentration of magnetic fields on the face of the magnet of the present invention are focused directly to the filter housing and form magnetic loops therein that collect and hold ferrous metal particles against the interior walls of the filter housing; 
     FIG. 7 is a side elevation view, partly in section, showing a magnet assembly of the present invention attached to the outer end wall of a horizontally oriented filter; 
     FIG. 8 is a top plan view of a friction pad that may optionally be used to increase the friction between the outer end wall of the filter housing and magnet when the filter housing is oriented horizontally as shown in FIG. 7; and 
     FIG. 9 is a side elevation view of the friction pad of FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now in detail to the drawings, and initially to FIG. 1, there is shown one form of magnet assembly  1  in accordance with this invention attached to the outer end wall  2  of a canister type filter  3  commonly used for example to filter the lubricating oil of gasoline or diesel engines used to power automobiles, trucks, motorcycles, etc. The oil enters the filter  3  through a series of circumferentially spaced openings  4  at the inner end  5  of the filter and then passes through a suitable filter medium  6  before exiting the filter through a central discharge opening  7  as schematically shown in FIG.  1 . Such filters are effective in removing most contaminants from the fluid circulating through the filters, but not the minute ferrous metal particles that are produced through normal wear of such engine parts as piston rings, cylinder walls, bearing riding surfaces, etc. The magnet assembly  1  of the present invention will remove virtually all of these minute ferrous metal particles in the fluid by forming magnetic loops in the filter housing causing the filter housing to collect and hold the ferrous metal particles as described hereafter. 
     Referring now to FIGS. 2 and 3, magnet assembly  1  comprises a high strength magnet  10  made out of a slurry of various metals including for example neodymium iron boron. Magnet  10  is produced in a compression mold that forms the magnet into the desired disc shape. Once formed, the magnet is magnetized to provide a plurality of circumferentially spaced pairs of poles N and S on the face  11  of the magnet. In the embodiment disclosed herein, four uniformly spaced pairs of poles are provided around the face  11  of the magnet  10 . However, it will be appreciated that fewer or more pairs of poles may be provided depending on the required size and strength of the magnet. 
     Providing plural pairs or sets of circumferentially spaced poles on the magnet face  11  concentrate the magnetic strength on the magnet face. The magnetic fields between the poles are relatively short and are focused directly on the ferrous metal filter housing  12  to form magnetic loops  15  in the walls of the filter housing when the magnet assembly  1  is attached to the outer end wall  2  of the filter as schematically shown in FIG.  6 . These magnetic loops  15  in the filter housing  12  will attract and trap virtually all ferrous metal particles in the fluid circulating through the filter against the inside walls of the filter housing. 
     The inner side  18  of the magnet face  11  that engages the outer end wall  2  of the filter housing  12  may be provided with a 10° conical taper to generally conform to the concave rounded outer contour of most filter end walls. Also, a hole  19  is provided through the center of the magnet of a size for receipt of a nut  20  on the outer end of some filters as schematically shown in FIG.  7 . 
     The magnet  10  is contained within a cup-shaped plastic housing  21  that completely covers the outer edge  22  and outer side  23  of the magnet face  11  as schematically shown in FIGS. 3 and 7 to provide some protection to the magnet against breakage in the event the magnet assembly is inadvertently dropped on a hard surface, and to cover the outer end of the center opening  19  in the magnet to prevent debris from entering the opening from the exterior. Also a ferrous metal disc  25  that may be electroplated with tin may be positioned against the outer surface of the end wall  27  of the plastic housing  21  in close proximity to the outer side  23  of the magnet face  11  as schematically shown in FIGS. 3 and 7. Metal disc  25  (which is shown by itself in FIGS. 4 and 5) aids in focusing the magnetic flux on the magnet face  11  which forms the magnetic loops on the walls of the filter housing as previously described. 
     The magnetic force of the magnet  10  is sufficient to hold the metal disc  25  in place against the end wall  27  of the plastic housing  21 . However, a suitable adhesive may be used to permanently secure the metal disc  25  to the plastic housing end wall  27  if desired. Also, a decal  28  or the like made of a suitable material such as plastic or paper may be adhesively secured to the outer surface of the metal disc  25  to cover the metal disc as further shown in FIGS. 3 and 7. 
     To install the magnet assembly  1 , the inner side  18  of the magnet face  11  is simply placed against the outer end wall  2  of the filter housing  12  as schematically shown in FIGS. 1,  6  and  7 . The magnetic force of the magnet acting on the filter housing  12  is sufficient to hold the magnet assembly in place against the filter. However, if the filter is mounted horizontally as shown in FIG.  7  and is subject to high vibration, a friction pad  30  (shown by itself in FIGS. 8 and 9) may be placed between the magnet assembly  1  and filter end wall  2  to guard against the possibility of the magnet assembly sliding sideways on the filter housing. Friction pad  30  may be made out of a suitable plastic tape, and is in the shape of a ring with a center hole  31  similar to the shape of the magnet face  11 . One side  32  of friction pad  30  is coated with an aggressive pressure sensitive adhesive for secure attachment to the outer end wall  2  of the filter housing  12 . The other side  33  of the friction pad  30  is desirably coated with a less aggressive pressure sensitive adhesive to provide just enough frictional resistance with the inner side  18  of the magnet face  11  to prevent the magnet assembly from sliding sideways relative to the filter housing end wall, while still permitting the magnet assembly to be peeled off the filter and reused over and over with a new filter whenever the lubricating fluid is changed and the filter is replaced. Removable protective sheets  34  or the like may be used to cover both sides of the friction pad  30  as shown in FIGS. 8 and 9 to protect the friction pad from adhering to a surface until the protective sheets are removed. 
     Although the dimensions of the magnet may vary, in one embodiment of the invention, the magnet has an outer diameter of approximately 2.85 inches so that it will readily fit most standard oil filters having a diameter of between 2 inches and 6 inches. Also, the magnet has a thickness at its outer edge of approximately ½ inch, and a center hole diameter of approximately 1 inch. Moreover, the plastic housing  21  has a wall thickness of approximately 0.070 inch and the flux concentration disc  25  has a thickness of approximately 0.030 inch. 
     From the foregoing, it will be appreciated that the magnet assembly of the present invention, when used with an oil filter for an engine, will extend engine life and allow the engine to produce peak power over a longer period of time by removing virtually all of the ferrous metal particles in the oil. Also, the magnet assembly may be used to remove ferrous metal particles from fluid circulating through other types of filters as well including for example hydraulic fluid return line filters and the like. 
     Although the invention has been shown and described with respect to certain embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. In particular, with regard to the various functions performed by the above described components, the terms (including any reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed component which performs the function in the herein exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one embodiment, such feature may be combined with one or more other features of other embodiments as may be desired and advantageous for any given or particular application.

Technology Classification (CPC): 1