Note: Descriptions are shown in the official language in which they were submitted.
2105636
REUSABLE FILTER
Field of the Invention
The present invention is directed toward a filter, and in particular,
towards a reusable metal filter for filtration of fluids.
Background of the Invention
There has been a demand in industry, in view of environmental
concerns, for reusable filters. Previously filters were employed which had paper or
cotton filter elements which were disposed of after use. Reusable filters were
developed using metal filter elements, similar to the paper filters. In these filters,
10 randomly oriented metal fibres were pressed together form a filter element.
Because of the random orientation of the fibres, the filter did not offer uniform
filtration throughout the entire filter surface.
Woven metal cloth has been used to produce reusable filters. A metal
cloth filter element offers uniform filtration throughout the filter surface because of
15 the controlled weaving method employed in the cloth production. In previouslyknown filters the cloth has been flat wrapped, however, requiring frequent cleaning
and maintenance of the filters.
Summarv of the Invention
It has been discovered that a low maintenance, reusable filter can be
20 provided by using a woven metal cloth filter disposed in a pleated arrangement.
Pleating the metal cloth allows greater flow rates and greater effective surface area
for filtering activity over flat wrapped filters. The filter of the present invention can
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be used in engine oil and engine coolant filtration, as well as the filtration of glycol
and waste water.
According to a broad aspect of the present invention there is provided
a filter for filtration of fluids comprising:
a pleated metal filtering element supported on a first side thereof by a
first perforated support wall and on a second side thereof by a second perforated
support wall such that the filtering element is sandwiched between the first support
wall the second support wall and fluids flow through the first support wall to be
filtered through the filtering element and exit through the second support wall.According to further broad aspect of the present invention there is
provided a substantially cylindrical filter for filtration of fluids comprising:a pleated metal filtering element supported by an inner perforated tube
and an outer second perforated tube such that the filtering element is sandwiched
between the inner tube and the outer tube and fluids flow through a selected one of
the inner tube or outer tube to be filtered by the filtering element and exit through
the other of the inner tube or outer tube.
Brief Description of the Drawings
FIG. 1 is a perspective view of the filter of the present invention;
FIG. 2 is a cross-sectional view of the filter of the present invention;
FIG. 3 is an enlarged view of the filter element and supports as shown
in FIG. 2; and,
FIG. 4 is an exploded, sectional view of the filter of the present
invention.
Detailed Description of the Present Invention
As shown in Figure 1, the filter 10 of the preferred embodiment of the
present invention is of use in engine oil filtration and comprises a pleated metal filter
element 12 supported by an inner perforated tube 14 and an outer perforated tube
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16. In the preferred embodiment, metal filter element 12 is maintained in its pleated
arrangement by a pleated support 17. The filter element 12 and supports 14, 16
and 17 are maintained in position by a pair of end caps 24. A gasket 28 is
provided on each end cap 24 to effect sealing between the filter 10 and the housing
5 (not shown) in which it is disposed when in use.
As best shown in Figure 2, filter element 12 and pleated support 17 are
correspondingly pleated and fitted together in close contact with each other. In this
way, filter element 12 is supported by pleated support 17, against deformation by
the pressure of the fluid flow. Inner tube 14 and outer tube 16 closely sandwich the
10 pleated filter element 12 and support 17. In the preferred embodiment, the direction
of flow during filtering is intended to be through the filter from outside to the central
cavity of the filter, indicated generally at 22. To accommodate this direction of flow,
support 17 is positioned adjacent the inner tube 14.
The pleated support can be repositioned to support the filter cloth
15 against any selected direction of flow in the filtering system. According to the
invention, the pleated support will support the filter element against the flow of the
fluid. In a system where the direction of flow during filtering is intended to be
through the filter from the central cavity to the outside, the pleated support will be
positioned adjacent the outer tube. In a system where flow can be alternately in two
20 directions, a support can be provided on each side of the filter element. This is the
case in a system where fluid to be filtered flows in a first direction, while filter
cleaning takes place by back flushing a cleaning fluid in a reverse direction.
Metal filter element 12 is preferably formed from stainless steel woven
cloth. Stainless steel is able to withstand the temperature and flow pressures
25 normally found in engines and will not be easily corroded. It has been found that
a dutch twilled stainless steel cloth, having a pore size greater than about 1 micron
or dutch weave stainless steel cloth having a pore size of from 20 to 300 microns
are preferred. Uniform filtration across the entire filter surface is provided by use of
such a filter element. The filter element is pleated to increase the effective surface
30 area of the filter. In the preferred embodiment, the pleats are formed to have a
frequency of 1 to 10 pleats/inch.
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Pleated support 17 is preferably a metal mesh material. In the most
preferred embodiment, support 17 is formed from stainless steel mesh, although
other metals may be used. To provide optimum support for filter element 12, while
allowing optimum flow of liquid, a 60 mesh size dutch weave stainless steel support
5 is preferred.
Inner tube 14 and outer tube 16 are preferably formed from mild sheet
steel. However, in corrosive environments, inner tube 14 and outer tube 16 are
preferably formed from stainless steel. Inner 14 and outer 16 tubes are each
perforated to allow the flow of fluid through filter element 12, while supporting filter
element 12 against the force of the fluid flow. Inner 14 and outer 16 tubes further
act to provide an encasement for the filter 10 and protect the filter element 12 from
being damaged during use and cleaning. Perforations 18 on the inner tube 14 and
perforations 20 on the outer tube 16 are respectively sized and distributed
depending on the desired flow rate to provide optimum support for the filter while
15 minimizing hydraulic drag. In the preferred embodiment, inner tube 14 is provided
with perforations 18 of 1/4 inch diameter on 5/16 inch centres, while outer tube has
5/8 inch diameter perforations on 13/16 inch centres.
To maintain the filter element 12, support 17 and tubes 14 and 16 in
position, end caps 24 are provided which fit over each end of the filter without20 blocking access to central cavity 22. Preferably, the caps 24 have flanged edges
26 to extend a short distance over the edge of the inner 14 and outer 16 tubes. End
caps 24 are held in place on the filter by any suitable means, such as, for example,
by welding or crimping. Preferably, an adhesive, such as for example epoxy, is
used to secure end caps 24. Such an adhesive provides additional stability to filter
25 10 and prevents fluid from circumventing filtration by flowing between the cap and
the edge of the filter element.
Gasket 28 is provided on each end cap 24 to effect sealing between
filter 10 and the housing of the engine when in use. Gasket 28 is formed of a
suitable sealing material and selected to be resistant to break down by filtering fluids
30 and cleansing agents as known in the art, such as ethylene propylene dimethyl(EPDM) rubber or buna-nitrile. The gaskets 28 are attached to the end caps by
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means of suitable adhesives, such as for example, Black MaxTM 39050 of Loctite
and ProntoTM CA40H available from 3M. The adhesives are also selected to be
resistant to break down by filtering fluids and cleansing agents.
Referring now to Figure 4, the filter 10 of the preferred embodiment is
5 assembled by forming the filter element 12 into a longitudinally pleated tube and
sealing the side of the tube by a fuse welding the joint (not shown). Support mesh
17 is pleated in correspondence with the pleats of filter element 12 to form a
cylindrical tube. The side joint of the support mesh 17is also sealed by fusion
welding. The pleated filter element 12 is then fit over pleated support 17. The filter
10 element 12 and support mesh 17 may alternatively be pleated together in one
operation. The joints may then be fuse welded together in one operation. The
combination of filter element 12 and support 17 are fit over inner tube 14 with
support 17 in close contact with inner tube 14. Outer perforated tube 16 is slipped
over the assembled pleated combination adjacent the filter element 12. Gaskets 28
15 are attached to end caps 24 and end caps 24 are attached, by means of adhesives,
to the ends of the arranged combination of outer tube 16, filter element 12, support
17 and inner tube 14 to produce a complete, reusable filter 10.
In use, fluids to be filtered first pass through perforations 20 of outer
tube 16. Filtration is effected when the fluids next pass through the filter element
20 12. The fluids then pass through support material 17 and out through perforations
18 of inner tube 14 into central cavity 22 of the filter 10.
As the filter is used, particulate from the fluid is accumulated on the
outer surface of the filter element and especially in the depths of the pleats of the
filter element. As the pleats accumulate particulate, the fluid continues to flow
25 through the filter element by passing through the filter element at the peaks of the
pleats. Eventually the particulate will accumulate on the filter element to an extent
where the flow through the filter element is restricted and the filter will have to be
cleaned to remove the particulate and restore the effective filtering action of the
filter. Cleaning of the filter is effected by flushing or soaking the filter unit with
30 appropriate solvents to remove the particulate. The filter of the present invention
can undergo repeated cycles of use and cleaning.
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The filter of the present invention can be modified for special uses
aside from those previously discussed. The filter of the present invention can be
used to filter engine coolant or in the filtration of glycol or waste water. The size and
shape of the filter, as well as the material used to produce the filter, can be adapted
5 to be suitable for the particular system where use of the filter of the present
invention is desired.
It is to be understood that the pleated support is only required for
support of the metal filtration element. Thus, where the metal filtration element is
of a construction able to withstand the force of the fluid flow without being deformed
10 the support can be completely omitted from the filter. It has been found that metal
cloth having a pore size of greater than about 100 microns can be used without apleated support.
End caps and gaskets may be omitted from the filter, depending on the
design of the housing into which the filter is to be placed. Where the housing
15 provides for filter stability and/or sealing means the end caps and/or gaskets are not
required for the functioning of the filter.
It will be apparent that many other changes may be made to the
illustrative embodiments, while falling within the scope of the invention and it is
intended that all such changes be covered by the claims appended hereto.
