Note: Descriptions are shown in the official language in which they were submitted.
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MAGNETIC FILTER AND MAGNETIC FILTERING ASSEMBLY
FIELD OF THE INVENTION
The invention relates to a magnetic device for extracting ferrous particles
from a body of
fluid. More particularly, the present invention is directed to a high strength
magnetic device
that is suitable for use within a housing, conduit or the like through which
fluids flow. The
invention also relates to an assembly utilizing the magnetic d.evice for the
extraction of
ferrous particles from a body of fluid.
BACKGROUND OF THE INVENTION
In industry, it is frequently necessary to remove ferrous particulate
contaminants from
liquids, such as, for example, lubricating oils, coolant fluids, water, fuels,
pump fluids and
hydraulic fluids. The use of magnets for this purpose has long been
recognized. Attempts
have been made to provide a device in which a rod-type magnetic assembly is
placed within a
cylindrical vessel through which fluid flows, including the devices disclosed
in US Patent
No.'s 4,026,805; 4,176,065, 4,450,075; and 4,883,591. These devices operate on
the
principle that ferrous particles adhere to the magnetic assembly by magnetic
attraction and
are thereby isolated from the body of fluid.
The devices indicated above, and other similar devices, however, collectively
present a
number of drawbacks. For example, they may utilize low strength magnets, may
not offer
ease of cleaning, or may be constructed of non-ferrous metal that may allow a
dangerous
electrical build-up and transfer. In addition, none of the previously
disclosed devices are
suitable for use with gearbox applications, as they generate a magnetic field
around the entire
magnetic device including one from the tip resulting in the magnetization of
the ferrous gear
or shaft and trapping of ferrous contaminants thereon.
Previous assemblies that employ magnetic rods for fluid treatment often
include screens,
baffles or rings so that there is a resultant restriction to fluid flow. These
assemblies require
complex bypass systems including pressure release valves. Furthermore, many
previous
devices result in essentially laminar flow of fluid along the length of the
magnetic rod such
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that filtration of the fluid is inefficient. Finally, some of the previously
disclosed devices are
designed for specific uses and as such are not adaptable to a variety of
systems for which
extraction of ferrous particulate contaminants is desired.
SUMMARY OF THE INVENTION
The present invention provides a reusable high strength magnetic device for
the removal of
ferrous particulate contaminants from a body of fluid. The device can be
removably installed
within the interior of a wide variety of fluid containing systems, such as,
for example oil
filters, fuel reservoirs, hydraulic pumps, gearboxes, and gas lines. The
device is easy to clean
and is resistant to corrosion. The magnetic device creates a rnagnetic field
radially about it
but does not generate a magnetic field about its long axis, beyond at least
one end of the
device.
Further, the invention provides a magnetic filter assembly that results in
turbulent flow of
fluid around the magnetic device such that the fluid is forced to come in full
contact with the
magnetic field resulting in full filtration of the ferrous contar.ninants. In
one embodiment, the
assembly generates a spiral fluid flow path. The spiral flow offers a
reasonably long flow
path in a compact device. In addition, the assembly has an iriternal cross
sectional area that
tends not to restrict the flow path of the fluid or require bypass systems
including pressure
release valves.
Accordingly, a broad aspect of the present invention provides a reusable
magnetic device for
the extraction of ferrous particles from a body of fluid, wherein the device
comprises a
plurality of magnets and soft ferrous metal spacers arranged in an alternating
sequence to
form a stack, adjacent magnets being arranged with like poles facing, a non-
magnetic and
non-ferrous end piece terminally disposed at a first end of the stack, and a
non-magnetic
housing that contains the magnets, the spacers and the end piece.
In accordance with another broad aspect of the invention there is provided a
reusable
magnetic device for the extraction of ferrous particles from a. body of fluid,
wherein the
device comprises a plurality of magnets and soft ferrous metal spacers
arranged in an
alternating sequence to form a stack, adjacent magnets being arranged with
like poles facing,
a non-magnetic and non-ferrous end piece terminally disposed at a first end of
the stack and a
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non-magnetic housing that contains the magnets, the spacers and the end piece,
the end piece
being selected such that a magnetic field is not present at the terminal tip
of housing adjacent
the end piece, and means for removeably attaching the rod inside a vessel
containing the body
of fluid on the housing at a second end opposite the first end.
In accordance with yet another broad aspect of the invention., there is
provided a magnetic
filter assembly for the extraction of ferrous particles from a body of fluid
comprising a
magnetic rod including a plurality of magnets and soft ferrous metal spacers
arranged in an
alternating sequence to form a stack, adjacent magnets being arranged with
like poles facing,
a non-magnetic and non-ferrous end piece terminally disposed at a first end of
the stack, and
a non-magnetic housing that contains the magnets, the spacers and the end
piece, the end
piece being selected such that a magnetic field is not present at the terminal
tip of housing
adjacent the end piece; and a cylindrical vessel within which the magnetic rod
is removeably
mounted, the vessel having fluid inlet adjacent its first end and a fluid
outlet adjacent its
second end.
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 perspective view of a magnetic device according to the present
invention with
the housing partially cut away to expose the magnets.
Figure 2 is a sectional view along line 2-2 of Figure 1.
Figure 3 is a perspective view of a magnetic device according to the present
invention
wherein the device is in operative position within a fluid filter.
Figure 4 is a perspective view of a magnetic device according to the present
invention
wherein the device is in operative position within a fluid reservoir.
Figure 5 is a perspective view, partially in section of a magnetic filter
assembly according to
the present invention.
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Figure 6 is a sectional view along line 6 - 6 of Figure 5.
Figure 7 is a sectional view through another magnetic filter assembly
according to the present
invention.
Figure 8 is a perspective view, partially cut away of another magnetic device
according to the
present invention.
DETAILED DESCRIPTION OF THE LNVENTION
Referring to Figures 1 and 2 there is illustrated a magnetic device 1 in
accordance with an
embodiment of the present invention wherein a relatively high magnetic field
is obtained by
utilizing a stack of strong disc magnets 2 and soft metal disc spacers 3. The
stack of magnets
and spacers are arranged in alternating positions along the length of the
stack with a spacer
positioned between each adjacent set of magnets in series. The magnets each
are positioned
with like poles facing each other through the intervening spacers. Preferably,
a spacer is
positioned at each end of the stack. The spacers can have approximately the
same diameter
as the magnets to facilitate stacking. In this arrangement, magnetic fields 4
generated from
adjacent like poles confront each other at the middle of the intervening
spacer thereby
creating longitudinally compressed magnetic fields of increased penetration.
The stack may
be comprised of any number of magnets and spacers.
While any type of magnet may be used, it is preferred that rare-earth magnets
are used to
maximize the magnetic force of the assembly. For most applications, a
vibration resistant,
high heat, rare-earth magnet is preferred such as, for example, a neodymium
boron magnet.
It is required that the spacers are made, of ferrous materials in order that
the spacer extends
the magnetic field surface area and assists in redirecting the i.ields.
Although the spacers may
be of a variety of soft ferrous metal constructions, the use of cold rolled
iron is preferred.
Cold rolled iron provides low resistance to the magnetic fielci while also
being highly
magnetic.
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While a cylindrical magnet/spacer shape is preferred for strength and ease of
handling, it will
be appreciated that shape of the spacers and magnets may vary from that
described here. The
use of components of solid construction, however, provides for the greatest
field strength.
5 To substantially reduce the magnetic fields at an end of the device, a non-
ferrous end-piece is
attached at one end of the stack. In this manner, the device may be easily
cleaned of adhering
particles by simply wiping any particles magnetically attached thereto to the
end of the device
from which they will fall off. The end-piece can be of a variety of materials
including wood,
copper and plastic. Preferably, the end piece is shaped similarly to the
magnets to facilitate
assembly. If it is desirable that both ends be without magnetic field, an end-
piece can be
placed at both ends of the stack, as shown.
The stack of magnets 2, spacers 3 and end-piece 5 are contained within a
housing 6. Housing
6 is formed of a non-magnetic material resistant to damage n the environment
in which the
magnetic device is to be used. A particularly useful material for forming the
housing is
stainless steel since it is resistant to both corrosion and impact damage in
many
environments. In addition, because of the strength of stainless steel the
housing can be very
thin-walled. Thereby reducing interference with the magnetic fields.
Housing 6 in the illustrated embodiment includes a sidewall 6a and a pair of
end plugs 6b.
The sidewall is formed of, for example, stainless steel tubing; and the end
plugs are welded
into place. End plugs 6b can also be secured by other means such as adhesives
or snap rings.
Of course, the housing can be constructed of other materials such as plastics,
as previously
noted.
Housing 6 can be any shape and size. Preferably, housing 6 closely surrounds
the magnets.
It has been found that a cylindrical form is most useful as it works best with
fluid flow
therepast.
To reduce damage both to the housing and to the magnets by vibration,
preferably the
magnets 2, spacers 3 and end pieces 5 are secured together by adhesive. In
addition, adhesive
can be applied between the internal parts 2, 3 and 5 and housing 6.
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As the device will be utilized within a fluid containing apparatus, attachment
means for
securing the device to such an apparatus is provided. The attachment means may
vary
depending on the application, and can include, for example, a threaded rod 7
for engagement
into a threaded aperture or fastener or a magnet for magnetic attachment to
apparatus
constructed of ferrous materials. In any case, the attachment means is firmly
attached to one
end of the magnetic device, such as, for example, by welding, or adhesive
attachment to
housing 6.
Figures 3 and 4 exemplify the use of the magnetic device wit:hin different
types of fluid
containing apparatus. Figure 3 shows a magnetic device 1 a according to the
present
invention within the core of a fluid filter 8, such as an oil filter. In this
case, device 1 a
includes a magnetic base 10, including a strong magnet secured within a
cavity, attached at
one end of the housing to secure the device by magnetic attraction to the
metal bottom 11 of
the filter. In this example, fluid flows into the core of the filter from the
top of the filter and
out through the barrier filtration media 9. To maximize the efficiency of the
magnetic
filtration, the magnetic device is centrally located within the core. Because
the magnetic
filter removes ferrous contaminants before they encounter the barrier filter,
the barrier filter
does not become clogged with such contaminants and therefore the usefulness of
the barrier
filter is increased. Furthermore, while the barrier filter may not retain
particles below a
certain size, the magnetic filtration is not size-dependent. The overall
efficiency of the
filtration system is therefore greatly improved with use of the magnetic
filter.
Having a magnetic attachment to the filter, magnetic device l a can be
removed, cleaned and
installed in another or same filter. Wiping accumulated debris to end 1'
opposite magnetic
base 10 cleans the device. End 1', having a copper end-piece therein, does not
have a
magnetic field associated therewith. At end 1' any debris caan be wiped off
easily without
having to overcome magnetic attractive forces.
Figure 4 demonstrates the placement of a magnetic device 1 according to the
present
invention within a fluid reservoir 13. In this case, device 1 is placed
directly in front of the
fluid outlet 14 of the reservoir so as to magnetically attract particles
flowing past the device
and into outlet 14. The device is secured, by threaded connection, to an
elongate rod 15. The
rod can be any desired length suitable to position device 1 in a selected
location within a
reservoir. Rod 15 and device 1 are inserted through a port in. the reservoir
wall. A bolt 16 is
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attached to a threaded portion 17 on the rod to secure the rod and the device
within the
reservoir. Of course, to avoid the use of an extension rod, magnetic device 1
could have been
elongated. However, this would increase cost.
Referring to Figures 5 and 6 there is illustrated a magnetic filtering
assembly. The assembly
includes a cylindrical vessel 19 in which a magnetic rod lb, such as that
described above, is
positioned. The vessel can be formed of any material resistaant to damage by
the fluids to be
passed therethrough. Common materials are aluminum, stainless steel and
plastics. The
vessel has an inlet 20 and an outlet 21 connected to sidewall portions of the
vessel and
positioned to be offset from the central axis 19x of the vessel. The inlet is
positioned near the
bottom of the vessel and the outlet is positioned near the top of the vessel.
Fluid enters the
vessel though the inlet and is deflected by the vessel sidewal:l and the
magnetic rod to flow in
a spiral fashion through the vessel. As the fluid travels upwards through the
vessel towards
the outlet, it continues to flow in a spiral around the rod until it leaves
the vessel through the
outlet. This circular flow of the fluid around the rod creates turbulence in
the fluid flow and
effectively increases the path length by which fluid is required to travel
through the vessel
and past the rod as compared to previous filtering assemblies. wherein laminar
flow of fluid
was common. Consequently, the efficiency of the magnetic filtration is
increased.
Preferably, rod lb is positioned generally concentrically within the vessel.
To provide for
easy removal and replacement of the rod for cleaning, the rod is secured to a
removable cap
23. The cap can be secured to the vessel by threaded engagement or other means
such as
quick couplers. To remove the rod, the cap is removed and the rod being
attached to the cap
is removed with the cap. The rod is stabilized within the vessel by insertion
into an
indentation 24 in the lower end of the vessel.
In use, vessel 19 is connected into a fluid flow conduit between a supply pipe
25 and an exit
pipe 26. To permit removal or opening of the vessel, valves 27 are provided in
the supply
pipe and the exit pipe to shut off the flow of fluid. To provicle for taking
the vessel off line
while the fluid continues to flow through the fluid flow conduit, preferably a
bypass pipe 28
is installed between supply pipe 25 and exit pipe 26. Valve 29 controls the
flow of fluid
through bypass pipe 28.
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Inlet 20 is selected to have a cross sectional area about equal to or greater
than the cross
sectional area of the supply pipe connected to the inlet, such that there is
no restriction to
fluid flow into the vessel. In addition, there is no restriction to flow
through the vessel.
Preferably, outlet 21 has a cross sectional area about equal to or greater
than the cross section
area of the inlet.
Another magnetic filtering assembly according to the present invention is
shown in Figure 7.
The assembly includes a vessel 30 and a magnetic rod 1 similar to that
described in Figure 1.
The vessel includes an inlet 32 at its first end and an outlet 34 at its
opposite end. Each of the
inlet and outlet include a quick coupler for easy connection into a fluid flow
conduit. A first
baffle 36 is mounted within the vessel adjacent the inlet and a second baffle
38 is connected
adjacent the outlet. Baffles 36, 38 are generally conical including apertures
39 formed
therethough. Baffles 36, 38 tend to create turbulence in fluid flowing
therepast and increases
the amount of fluid passing through the strong magnetic field generated close
to rod 1. The
total open area of the apertures on each baffle are about equal to or greater
than the cross
sectional area of the inlet, such that no resistance to flow is created by
passing through the
baffle.
Baffle 36 includes a central threaded aperture 40 though which rod 1 is passed
and engaged
by threaded portion 41 on an end of the rod. Rod I is stabilized by insertion
into an
indentation 42 at the center of baffle 38.
To access rod I for cleaning vessel includes a threaded cap 43a at one end. To
facilitate
assembly, a cap 43b can form the opposite end of the vessel and be secured by
welding,
threaded engagement or other means. Magnetic filtering assemblies according to
the present
invention can be installed in-line for a variety of applications.
With reference to Figure 8, because of the strong magnets in a device 1
according to the
present invention, the device can sometimes be magnetically attracted to
various parts of a
ferrous tank in which it is positioned. This can inhibit placement to and
removal of the
device from the tank. Therefore, in one embodiment, a spacing sleeve 44 is
positioned
around the device. The sleeve has large openings 46 to permit flow of fluid
therethrough and
into contact with device 1. However, sleeve 44 is formed of a rigid, non-
magnetic material
such as plastic or stainless steel and maintains spacing between surrounding
surfaces and the
device so that strong magnetic attraction therebetween cannot be established.
Sleeve 44 can
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be secured to the rod in any desired way. In the illustrated ernbodiment,
sleeve 44 includes
an end wall 48 with a centrally located aperture 50 therethrough. Aperture 50
is inserted over
threaded rod 7 prior to installation of the device in a fluid container.
