MAGNETIC FILTER ELEMENTS

ELEMENTS DE FILTRE MAGNETIQUES

English Abstract

A magnetic filter element has an elongate non-magnetic housing and a series of
magnets arranged in a column within the housing. Each magnet has a north pole
and a south
pole. The plurality of magnets is arranged with the north poles adjacent to
the south poles of
adjacent magnets. Non-magnetic spacer elements separate the plurality of
magnets in the
column.

Claims

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What is Claimed is:
1. A magnetic filter element, comprising:
an elongate non-magnetic housing;
a series of magnets arranged in a column within the housing, each magnet
having a
north pole and a south pole, the plurality of magnets being arranged with the
north poles
adjacent to the south poles of adjacent magnets; and
non-magnetic barrier separating the plurality of magnets in the column.
2. The magnetic filter element of claim 1, wherein the non-magnetic housing
comprises a
non-magnetic end cap that extends outward from the last magnet in the column
such that the
end cap forms a non-magnetic section at the end of the housing.
3. The magnetic filter element of claim 1, wherein the series of magnets are
spaced from a
mounting end of the housing to provide a non-magnetic section at the mounting
end of the
housing.
4. The magnetic filter element of claim 1, wherein the non-magnetic housing
comprises a
flange at a mounting end of the housing.
5. The magnetic filter element of claim 3, wherein the mounting end of the
housing
comprises external threads adjacent to the flange.
6. The magnetic filter element of claim 1, wherein a dipole moment of each
magnet is
parallel to the housing.
7. The magnetic filter element of claim 1, wherein a dipole moment of each
magnet is
perpendicular to the housing.
8. The magnetic filter element of claim 1, wherein the non-magnetic barrier is
a non-

7
magnetic spacer element.
9. The magnetic filter element of claim 1, wherein the non-magnetic barrier is
air.

Description

CA 02692316 2010-02-12
TITLE
[0001] Magnetic filter elements
FIELD
[0002] This relates to a magnetic filter element.
BACKGROUND
[0003] United States patent no. 6,143,171 (Van Aarsen) entitled "Magnetic
device for
treatment of fluids" describes a magnetic device that is used to remove
ferrous particles from
a fluid. The magnetic device has a series of magnets arranged in a column with
like poles
facing one another and separated by magnetically permeable discs.
SUMMARY
[0004] There is provided a magnetic filter element, comprising an elongate non-
magnetic
housing and a series of magnets arranged in a column within the housing. Each
magnet has a
north pole and a south pole. The plurality of magnets is arranged with the
north poles
adjacent to the south poles of adjacent magnets. Non-magnetic spacer elements
separate the
plurality of magnets in the column.
[0005] The non-magnetic housing may comprise a non-magnetic end cap that
extends
outward from the last magnet in the column such that the end cap forms a non-
magnetic
section at the end of the housing. The series of magnets may be spaced from a
mounting end
of the housing to provide a non-magnetic section at the mounting end of the
housing.
[0006] The non-magnetic housing comprises a flange at a mounting end of the
housing.
The mounting end of the housing may comprise external threads adjacent to the
flange.
[0007] A dipole moment of each magnet may be parallel or perpendicular to the
housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] These and other features will become more apparent from the following
description in which reference is made to the appended drawings, the drawings
are for the
purpose of illustration only and are not intended to be in any way limiting,
wherein:

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FIG. 1 is a side elevation view in section of a magnetic filter element.
FIG. 2 is a side elevation view in section of an alternative magnetic filter
element.
FIG. 3 and 4 are side elevation views of alternative housings.
FIG. 5 is a perspective view of a series of magnets.
FIG. 6 and 7 are side elevation views of alternative non-magnetic barriers.
DETAILED DESCRIPTION
[0009] A magnetic filter element, generally identified by reference numeral
10, will now
be described with reference to FIG. 1 through 7.
Structure and Relationship of Parts:
[0010] Referring to FIG. 1, magnetic filter element 10 has an elongate non-
magnetic
housing 12 and a series of magnets 14 arranged in a column within housing 12.
Preferably,
magnets 14 are rare earth magnets, such as NdFeB magnets, or other strong
magnets. As
shown in the depicted embodiment, magnets 14 may be sized to fit closely
within housing 12.
Preferably, housing 12 is a cylindrical housing, and, referring to FIG. 4,
magnets 14 are
shorter cylinders or puck shaped to fit within housing 12. Referring to FIG.
1, each magnet
14 has a north pole 16 and a south pole 18. Magnets 14 are arranged such that
north poles 16
and south poles 18 of adjacent magnets 14 are adjacent, and are separated by a
non-magnetic
barrier 20. Magnets 14 may be oriented such that their dipole moments are
parallel to
housing 12 as shown in FIG. 1, such that there is only one north/south
interface on each side
of magnets 14. In other words, if each magnet 14 is puck shaped, magnet 14
varies from
north to south along its height. Alternatively, referring to FIG. 2, the
dipole moment of each
magnet may be perpendicular to housing 12, such that magnets 14 vary along the
width rather
than their height. This results in two north/south interfaces for each side of
magnets 14, and
results in a more complex magnetic field pattern.
[0011] When opposite magnetic poles are adjacent, the magnetic field lines are
densely
positioned around the interface. This can be contrasted with magnetic field
lines when like
poles are adjacent, which extend perpendicular to each other out to infinity.
Opposite poles
result in a magnetic attraction that is very strong close to the interface of
the magnets, but

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3
tapers off quickly as one moves away from that interface. This can be used to
provide a
strong holding force on ferrous debris that is encountered in a liquid.
However, the debris
must get quite close to filter element 10 to be affected. As these opposed
poles are separated,
such as by non-magnetic barrier 20, the field lines move outward, such that
the strength of the
magnetic attraction close to the magnet is reduced somewhat, but extends
further outward.
Thus, there is a trade-off between the reach of the magnetic attraction, and
the strength of the
magnetic attraction. The size of the non-magnetic barrier 20 can be used to
select the desired
magnetic field. The design described herein is particularly useful in
situations where a
moving fluid is to be filtered, such as in engine lubrication systems,
hydraulic equipment or
other mechanical devices.
[0012] Non-magnetic barrier 20 may take different forms. For example, FIG. 6
shows a
non-magnetic spacer element 21, such as a disc, which may be composed of
various non-
magnetic materials and may have various thicknesses. Alternatively, non-
magnetic spacer
element 20 may be formed from a fluid. FIG. 7 depicts how this may be done by
providing
magnets 14 with protrusions 22 on the end of each magnet 14. The space may
then be filled
with a non-magnetic gas or liquid. While protrusions 22 may be magnetic, the
amount of
magnetic material will be small enough to minimize their effect on the
operation of filter
element 10.
[0013] In other embodiments, filter element 10 preferably has non-magnetic
portions at
one or both ends. Referring to FIG. 1, non-magnetic housing 12 may have a non-
magnetic
end cap 24 that extends outward from the last magnet 14 in the column such
that end cap 24
forms a non-magnetic section at the end of housing 12. This may be useful, for
example,
when cleaning a filter element, as the captured particles can be pushed toward
the non-
magnetic end where they are more easily removed. In addition, this may also
help avoid
inducing a magnetic dipole in the machinery that is close to end cap 24.
Similarly, there may
be a non-magnetic portion at a mounting end 26 of housing 12 formed by a non-
magnetic
element 27.
[0014] In order to install filter element 10, non-magnetic housing 12 may have
threads 28

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4
at mounting end 26 as shown in FIG. 3, a flange 30 as shown in FIG. 4, or
both. The
embodiment in FIG. 3 may be threaded into an aperture, while the embodiment in
FIG. 4
may be pin-connected into an aperture through holes 32.
Operation:
[0015] The embodiments shown in FIG.1 and 2 are assembled by providing a non-
magnetic housing 12. Magnets 14 are inserted into housing 12 to form non-
magnetic barriers
20 between each magnetic, and such that opposite poles are adjacent. End cap
24 and a non-
magnetic element 27 are provided, and the entire structure may be held
together by inserting a
threaded rod 34. As shown in FIG. 5, magnets 14 preferably have a central
aperture 35 to
facilitate this. Referring to FIG. 3 and 4, to facilitate installation,
housing 12 may have
threads 28, a flange 30, or both. Element 10 may then be installed such that
magnets 14 exert
a force on magnetic particles and debris in a fluid. Magnetic filter element
10 is particularly
useful for filtering moving fluids in relatively small spaces, and may be
inserted through an
aperture in a tank wall, such as in an engine lubrication system, hydraulic
equipment or other
mechanical devices.
[0016] To clean filter element 10, it is first removed from the fluid, and may
be wiped
clean by starting at the non-magnetic section at mounting end 26 and moving
toward non-
magnetic end cap 24. Alternatively, it may be pressure washed, or otherwise
cleaned as will
be recognized by those in the art.
[0017] In this patent document, the word "comprising" is used in its non-
limiting sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one element is present, unless the context clearly
requires that there
be one and only one of the elements.
[0018] The following claims are to be understood to include what is
specifically
illustrated and described above, what is conceptually equivalent, and what can
be obviously
substituted. Those skilled in the art will appreciate that various adaptations
and modifications

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of the described embodiments can be configured without departing from the
scope of the
claims. The illustrated embodiments have been set forth only as examples and
should not be
taken as limiting the invention. It is to be understood that, within the scope
of the following
claims, the invention may be practiced other than as specifically illustrated
and described.

Representative Drawing