Magnetic attachment for a filter

A plurality of magnets are detachably attached to the exterior of the cylindrical casing of a liquid filter unit to attract and capture ferromagnetic particles from the fluid, particles too small to be captured by the basic filtering element but large enough to cause further harm if allowed to remain free in the liquid. The magnets are magnetized such that their ends are north or south poles and shaped so that the ends are in close, positive contact with the casing. The attachment apparatus comprises springs interconnecting the magents and links and springs to position the magnets in the lengthwise direction of the casing.

BACKGROUND OF THE INVENTION 
1. FIELD 
The subject invention is in the field of filters used for removing 
particles from liquid flowing through the filters. More particularly it is 
in the field of filters intended for use with liquids in which 
ferromagnetic particles are entrained or suspended, such as the 
lubricating oil in internal combustion engines. Such particles are worn 
off the ferromagnetic parts of the engine during use and entrained in the 
lubricating liquid. The filters commonly used in the lubrication systems 
of internal combustion engines capture some of the particles and thus 
prevent them from possibly causing further wearing of the lubricated parts 
but it is well known in the art that filters able to capture the particles 
at the small end of the size range of such particles by filtering action 
are too cumbersome and expensive to be commercially successful. It is 
known to be possible to capture the smaller ferromagnetic particles by 
placing magnetic components in the filters as shown in the known prior art 
to the subject invention. 
2. PRIOR ART. 
Filters incorporating magnetic elements for the purpose of capturing 
ferromagnetic particles too small to be captured by the filtering elements 
are shown in the following patents: 
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U.S. Pat. Nos. British 
2,014,800 2,980,257 557,214 
2,838,179 3,840,045 
2,860,787 4,450,075 German 
4,629,558 478,770 
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None of the prior art apparatus for removing small ferromagnetic particles 
from lubricating oil are known to be commercially successful. One of the 
primary reasons for this lack of success is believed to be that the cost 
of the filters incorporating the magnetic means could not be justified in 
terms of tangible evidence of the economic benefits of using them. 
Therefore, the problem leading to the subject invention was provision of 
filtering apparatus which effectively captures small ferromagnetic 
particles in liquids and which does so at less cost than the known prior 
art apparatus provided for that purpose. Accordingly it is an objective of 
the subject invention to provide apparatus for capturing ferromagnetic 
particles in liquids, the cost of using such apparatus to be minimal. It 
is evident from the following descriptions that the cost minimization is 
achieved in part because the apparatus is reusable, being transferable 
from filter to filter and therefore a second objective of the subject 
invention is that it be separable from the filter apparatus with which it 
is used and repeatedly reusable on other filters. 
SUMMARY OF THE INVENTION 
The invention comprises a plurality of magnets detachably attached to the 
exterior of the conventional oil filters used on internal combustion 
engines. The effects of the magnets penetrate the casing of a filter and 
cause ferromagnetic particles entrained in the fluid flowing through the 
filter to be attracted to the inner surface of the casing and thus 
captured, preventing their further circulation in the lubricating liquid 
in the engine and thereby augmenting the function of the filter. In a 
preferred embodiment the magnets are rectangular segments of a cylinder 
with the inside diameter of the cylinder slightly smaller than the outside 
diameter of the cylindrical casing of the filter. The magnets are held 
against the casing by attachment apparatus described below, with the 
inside diameter surfaces of the magnets nested against the surface of the 
casing. The magnets are located spaced apart in a line around the casing. 
The ends of each magnet contact the casing because of the diameter 
difference stated above. The magnets are located relative to each other 
and held in place by tension springs interconnecting them. Clips and 
additional springs are used to position the springs and magnets at a 
position along the length of the casing and to maintain them in that 
position. The magnets are magnetized so that the ends of each magnet 
contacting the casing are a north and a south pole. The magnetic fields of 
the magnets attract and capture ferromagnetic particles in the liquid in 
the filter, particles too small to be captured by the filter itself but 
large enough to cause further engine wear if allowed to continue to 
circulate with the lubricating liquid.

DETAILED DESCRIPTION OF THE INVENTION 
The invention comprises a plurality of magnets detachably attachable to the 
exterior of a filter used, for example, in the lubricating system of an 
internal combustion engine. The fields of the magnets attract and capture 
ferromagnetic particles in the lubricating liquid too small to be captured 
by the filter apparatus itself but large enough to cause additional wear 
of parts if allowed to continue circulating with the fluid. FIG. 1 
illustrates an oil filter of the type used on internal combustion engines, 
the filter being fitted with the subject invention. The invention 
comprises a plurality of permanent magnets, of which magnet 11 is typical. 
The magnets are interconnected by a plurality of springs, spring 12 being 
typical and positioned in series around the exterior of the casing 13 of 
the filter. The ring of magnets is positioned lengthwise of the filter by 
pluralities of links and springs described in more detail below, link 14 
and spring 15 being typical. 
The function of the invention is shown in FIG. 2, a sectional view taken at 
2--2 in FIG. 1. As shown, the magnets are curved to conform to the 
cylindrical shape of the filter casing. However, the inner radius r of 
each magnet is smaller than the radius R of the external surface of the 
casing. As a result the magnets contact the casing at their ends, ends 17 
and 18 being typical. The magnets are magnetized such that their ends are 
north and south poles respectively as indicated by the letters S and N on 
each magnet. 
With the magnets positioned as described their fields attract and capture 
deposits of ferromagnetic particles, deposit 19 being typical, thus 
serving the primary purpose of the invention. 
FIG. 3 illustrates a magnet in detail. The magnet 11 is a rectangular block 
curved as shown in FIG. 2. Tabs 20 and 21 are used for interconnection of 
the magnets by springs and tabs 22 and 23 are used in locating the magnets 
in a position lengthwise of the filter. 
FIG. 4 illustrates an interconnection spring 12. Hooks 24 and 25 are 
inserted through holes in the appropriate tabs on the magnets, hole 26 
(FIG. 3) being typical, and closed to prevent inadvertent detachment of 
the springs from the magnets. The magnets are thus connected in series. 
FIG. 5 illustrates the springs and related apparatus used in positioning 
the series of magnets lengthwise on the filter casing. The apparatus 
comprises pluralities of springs and links, spring 27 and link 28 being 
typical, and a ring 29 positioned at the center (not visible) of bottom 30 
(FIG. 1). Hook 31 on link 28 is inserted through hole 32 (FIG. 3) and 
closed to prevent inadvertent disconnection. Hook 33 on spring 27 is 
similarly connected to tab 23 (FIG. 3) and hook 34 is connected to ring 
29. With the apparatus thus connected the magnets are installed on the 
filter by placing the series of magnets around the casing, extending the 
interconnecting springs in the process and sliding the ring of magnets 
toward the top end 35 (in FIG. 1) until hook(s) 36 of link(s) 28 hook over 
rim 37 (in FIG. 1), stretching spring(s) 27 in the process. The magnets 
are thus in position to serve their stated purpose. The cost of using the 
same magnets to assist the filtering action on many filters is lower than 
providing equivalent magnets in each filter. 
It is believed to be clear from this description that the invention meets 
it objectives. The apparatus is transferable from filter to filter and 
thus provides the supplementary filtering benefits at costs lower than the 
cost of providing supplementary filtering capability in each filter. 
It is also believed to be understandable by those skilled in the art that 
while one embodiment of the invention is described herein, other 
embodiments and modifications of the one described are possible within the 
scope of the invention which is limited only by the appended claims.