Note: Descriptions are shown in the official language in which they were submitted.
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CONICAL FILTER -
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a conical filter and in particular to a
conical
filter of fluted filter media for placement inline in a fluid stream, and a
method for
making the filter.
2. Description of the Prior Art
Fluid filters are used for a wide variety of applications. Fluid filters
typically
use a filter element inside of a housing having an inlet and an outlet so that
the fluid
passes through the filter media, thereby trapping particulate material.
Aerodynamic
conical filters are generally used for high velocity fluid flow applications,
such as
automobile air intake filters. In the past there has been little usage of
conical filters
mainly due to problems with size and effectiveness. Generally, these filters
have used
pleated filter media. With the pleated filters, straight through flow is not
possible.
1 S This causes high pressure differentials across the filter and flow
distribution problems.
To combat these problems, designers have generally increased the spacing
between
the pleats, thereby reducing the density of the filter media. This has reduced
the
effective life of the filters and has not solved the flow distribution
problem. These
filters have also had the added problem in that the filter media is not self
supporting.
Generally, rigid housings are required for use of these filters.
Another shortcoming with typical prior filter designs is unequal flow
distribution. Flow is often directed to a center portion of filters, thereby
loading the
filter unevenly. Portions of the filter may load over a much shorter interval,
thereby
requiring replacement of the filter element. However, if flow were directed
more
evenly over the entire filter, loading would be more uniform and more gradual,
so that
the filter life is extended.
An example of a conical filter is shown in U.S. Patent No. 5,106,397, issued
to
Ford Motor Company, April 21, 1992. In this patent, a pleated filter is used
to filter air
to an engine. To force air through the media, the top of each pleat is sealed
together so
that air cannot escape through gaps in the media. This allows an opening
between
each pleat for air to enter and flow down the pleat, through the media and out
the
inside center of the filter. In order to avoid restricting the incoming air,
the pleats must
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be apaced, thus limitinb tl:e amount of filtering media available tier
filtering. An ' .'
increase in filtering media results in an increase in pressure
differ°ntiai across the
fl l ttr.
European Patent Application FP-A-012513 shows is a filer element that has
a pleated Liltcr media and has portion:; of the opening hiocl:ed ofl~. Tile
pleated .nedia
is arranged to slope outwari in some embodiments.
U.S..~.. 2,~99,6U~1 snows Muted filter media in a cylindrical con.tiguration.
(t can be seen then, that ;:u~ improved conical filter is heeded which
provides
for increased filtering area without an accompanying high pressure
differential ;tcross
lU the Flter. Such a filter should also provide for improved Llow distribution
and even
loading over the entire tlltcr. 'Che present invention addresses these as well
as other
problems associated with conical fillers.
S'f.JI~IiI~L2RY OF THE INVENTION
16 The present invention is directed to a conical filter and in particular to
a
conical f Iter formed of fiuted filtering media.
In a preferred embodiment of the invention, the permeable filter media used in
the tI!tcr has comtgated sheets of filte.-ing material sealed to sheets of
filtering media
at a.lternatzno ends, :urtmi..ag Gllering Mutes, which can be rolled into a
conical shape.
20 The alternating ends of each flute arc sealed off such that the t7ttid
enters through t.l:e
dirty side of the flute and is forced through to the clean side such that the
pa,~ticulate
mate:ial i5 deposited onto the filtering media.
In a conical filter, the filter media is coiled in a spiraling configuration
about a
center winding portion, forming an upstream face and a downstream lace, such
that
2~ the filtering flutes are substantially parallel to the incoming fluid
flout. 1'h is allows
the dirty fluid to enter the filter media without making an abmpt directional
charge
<md, hence, reduces the pressure differential across the filter media..
Moreover,
because the fluid is allowed to enter the filtering media without making nn
abnlpt
directional change, it is not necvssaty to have spaces in between the
filtering flutes as
30 is necessary with pleated filters. Therefore, the present arrangezz~ent
allows for a
maYimtun filtering area for a given volume without a corresponding increase
i.n
pressure differential currently associated with the przor art devices and also
increases
the life of the f lter element.
AMENOEJ SHEET
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Another advantage of the conical shape is the distribution of particulate
across -
the filter. As the incoming dirty fluid hits the bullet-shaped face of the
conical filter,
the flow is pushed from the inner to the outer portion of the filter media
such that the
fluid flow across all portions of the filter is relatively even. This
distribution of
particulate further increases the filtering effectiveness and the effective
life of the filter
element.
The inline capability provides for a reduction in space with greater media
filtering area over presently used filter elements and housings.
The present invention also includes methods for making the conical filter.
According to a first method, the filter is made by providing a strip of fluted
filter media
having the plurality of fluted compartments formed therein. The filter media
is then
coiled about a mandrel. While the media is being coiled about the mandrel, a
bead of
sealant is applied to adjacent layers of the coil, thereby, closing off
alternate sections of
the fluted material. Before the sealant hardens, the coiled filter media is
placed on a
conical forming tool. By forcing the coiled filter media onto the conical
forming tool,
the center portion of the media is extruded longitudinally to form a conical
filter face.
The filter is then allowed to cool to a hardened state. According to a second
method,
the filter media is wound in a spiral, forming a conical filter face as the
filter media is
wound and the sealing bead is applied.
It can be appreciated that with the present invention, an increased filtering
area
can be accomplished without an accompanying increase in pressure differential.
Because of this, the present filter can accept higher fluid flows and has a
longer
effective life.
These features of novelty and various other advantages which characterize the
invention are pointed out with particularity in the claims annexed hereto and
forming a
part hereof. However, for a better understanding of the invention, its
advantages, and
the objects obtained by its use, reference should be made to the drawings
which form a
further part hereof, and to the accompanying descriptive matter, in which
there is
illustrated and described a preferred embodiment of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS _
In the drawings, wherein like reference letters and numerals indicate
corresponding elements throughout the several views:
Figure 1 shows a perspective view of fluted filter media for the filter
apparatus
according to the principles of the present invention;
Figures 2A-2B show diagrammatic views of the process of manufacturing the
filter media shown in Figure 1;
Figure 3 shows a detail perspective view of a layer of filter media for a
filter
according to the principles of the present invention;
Figure 4 shows a perspective view of the fluted filter media spiraled in a
cylindrical configuration according to the principles of the present
invention;
Figure 5 shows a detail perspective view of a portion of the spiraled fluted
filter media for the filter element shown in Figure 4;
Figure 6 shows a side elevational view of a first method of forming a conical
filter element on a conical forming support;
Figure 7 shows a second method of forming a conical filter element;
Figure 8 shows a side elevational view of a conical filter according to the
principles of the present invention;
Figure 9 shows a side elevational view of the conical filter shown in Figure 8
in combination with a filter housing;
Figure 10 shows a side elevational view of an alternate embodiment of the
invention wherein the filter is encased in its own housing and can be inserted
inline in
a fluid flow;
Figure 11 shows a side elevational view of a further alternate embodiment of
the present invention including a flow distribution vane;
Figure 12 shows a fluid velocity profile across the conical filter;
Figure 13 shows a side view of an alternate embodiment of the present
invention showing a fi~sto-conical filter; and
Figure 14 shows a side partial sectional view of the filter shown in Figure 13
and an associated housing.
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S
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and in particular to Figure 1, there is shown a
portion
of a layer of permeable fluted filter media, generally designated 22. The
fluted filter media
22 includes a multiplicity of flutes 24 which form a modified corrugated-type
material. The
flute chambers 24 are formed by a center fluting sheet 30 forming alternating
peaks 26 and
troughs 28 mounted between facing sheets 32, including a first facing sheet
32A and a second
facing sheet 32B. The troughs 28 and peaks 26 divide the flutes into an upper
row and lower
row. In the configuration shown in Figure 1, the upper flutes form flute
chambers 36 closed
at the downstream end, while upstream closed end flutes 34 are the lower row
of flute
chambers. The fluted chambers 34 are closed by first end bead 38 filling a
portion of the
upstream end of the flute between the fluting sheet 30 and the second facing
sheet 32B.
Similarly, a second end bead 40 closes the downstream end 36 of alternating
flutes 24.
Adhesive tacks 42 connect the peaks 26 and troughs 28 of the flutes 24 to the
facing sheets
32A and 32B. The flutes 24 and end beads 38 and 40 provide a filter element 22
which is
structurally self supporting without a housing.
During use, unfiltered fluid enters the flute chambers 36 which have their
upstream
ends open as indicated by the shaded arrows. Upon entering the flute chambers
36, the
unfiltered fluid flow is closed off by the second end bead 40. Therefore, the
fluid is forced
to proceed through the fluting sheet 30 or face sheets 32. As the unfiltered
fluid passes
through the fluting sheet 30 or face sheets 32, the fluid is filtered as
indicated by the
unshaded arrow. The fluid is then free to pass through the flute chambers 34,
which have
their upstream end closed and to flow through the downstream end out the
filter media 22.
With the configuration shown, the unfiltered fluid can filter through the
fluted sheet 30, the
upper facing sheet 32A or lower facing sheet 32B, and into a flute chamber 34
blocked on
its upstream side.
Referring now to Figures 2A-2B, the manufacturing process for fluted filter
media
which may be rolled to form filter elements, as explained hereinafter, is
shown. It can be
appreciated that when the filter media is spiraled, with adjacent layers
contacting one another,
only one facing sheet 32 is required as it can serve as the top for one fluted
layer and the
bottom sheet for another fluted layer. Therefore, it can be appreciated that
the fluted sheet
30 need be applied to only one facing sheet 32.
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As shown in Figure 2A, a first filtering media sheet is delivered from a
series _
of rollers to a crimping roller 44 forming a nip with a second opposed roller
45. In a
similar manner, a second sheet 32 is fed to the rollers 44 and 45. A sealant
applicator
47 applies a sealant 46 along the upper surface of the second sheet 32 prior
to
engagement between the crimping roller 44 and the opposed roller 45. As shown
in
Figure 2B, the first sheet 30 engages the corrugated surface of the roller 44,
and as it is
pressed between the opposed roller 45, takes on a corrugated or fluted
configuration
matching that of the corrugated roller 44. The troughs 28 have a sealant
applied at
their apex or are otherwise welded to the facing sheet 32 to form flute
chambers 34.
The sealant 46 forms first end bead 38 between the fluted sheet 30 and the
facing sheet
32. T'he resultant structure of the facing sheet 32 sealed at one edge to the
fluted sheet
30 is the layerable filter media 48, shown in Figure 3.
When forming a conical filter, a filter media spiral, as shown in Figure 4 is
formed. It can be appreciated that the filter media layer 48 having a single
backing
sheet 32 and a single end bead 38 shown in Figure 3 can be wound to form a
spiral
type cylindrical filter element, generally designated 52, shown in Figure 4
and shown
in greater detail in Figure 5. To form the spiral filter element 52, a bead of
sealant is
applied lengthwise on a mandrel 54. An end of the single sided fluted filter
media 48
is secured to the mandrel 54 via the bead of sealant. The single sided fluted
filter
media 48 is then rolled onto the mandrel 54 as a second end bead 40 along a
second
edge of the filter media is applied with the sealant applicator 47 to the
pleated side of
the single sided fluted filter media 48, as shown in Figure 4. As the pleated
filter
media 22 is rolled onto the mandrel 54, the second end bead 40 adheres to the
first
facing sheet 32 of the single sided fluted filter media 48, as shown in Figure
3. It can
be appreciated that when the filter media is wound onto the mandrel, with
adjacent
layers contacting and sealing peaks and troughs of flutes, only one facing
sheet is
required as it serves as the top layer for one flute and the bottom layer for
another flute.
Therefore, as the second end bead 40 adheres to the first facing sheet 32 the
downstream closed end flute 36 for the filter media spiral 52 is formed. When
the
required length of single sided fluted filter media 48 is rolled onto the
mandrel 54 such
that the diameter of the filter media spiral 52 is as required, an outer
sealing bead is
applied to the free end of the single sided fluted filter media 48. The free
end of the
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pleated filter media is then secured to the facing sheet 32 such that the free
end adheres -
to the filter media spiral 52.
The filter media is configured so that when filtering, dirty fluid, as
indicated by
the shaded arrows, enters the upstream open ended flute chambers 36 which have
their
upstream ends open. After entering the upstream open ended flute chambers 36,
the
unfiltered fluid engages the second end bead 40. Therefore, the fluid is
forced to
proceed through the fluting sheet 30. As the unfiltered fluid passes through
the fluting
sheet 30, the fluid is filtered as indicated by the unshaded arrow. The fluid
is then free
to pass through the downstream open end flute chambers 34, which have their
upstream end closed, and out the filter media 48. In addition, the u~ltered
fluid can
filter through the facing sheet 32 to the chambers 34.
The conical filters can be made by several manufacturing techniques. While
the sealant on the filter media spiral is still warm and pliable, the filter
is somewhat
moldable. In a first method, at this stage, the filter media spiral 52 is
pressed against a
conical forming tool 96, as shown in Figure 6, such that the filter media
spiral 52
forms a conical shaped element 62. The conical filter media spiral 52 is then
allowed
to remain on the conical forming tool until it reaches a hardened state and is
therefore
rigid. The conical filter element 62 is then removed from the conical forming
tool 96
and may be fitted with gasket seals 59.
It can be appreciated that the conical filter may also be made by the method
shown in Figure 7, wherein single-sided fluted filter media 48 is rolled onto
a mandrel
54. With the second manufacturing method, the mandrel moves axially relative
to the
sealant applicator 47. This causes the layer of single-sided filter media 48
to wind in a
spiraling configuration. The second end bead 40 is deposited by the sealant
applicator
which is held steady as the mandrel 54 and the already-wound filter media move
axially. In this manner, the second end bead 40 is at the leading face of the
conical
filter 62 which spirals outward to form a conical face. The second bead 40
seals the
adjacent layers of peaks and troughs of flutes so that only a single facing
sheet 32 is
required, as it serves as the top of one layer and the bottom of the next. It
can be
appreciated that the mandrel may be held axially stationary; however, this
requires that
both the sealant applicator 47 and the feed of the single-sided fluted filter
media 48
move axially relative to the mandrel so that a conical filter is formed.
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Referring now to Figure 8, there is shown a first embodiment of a conical
filter
60 having a conical filter element 62. The conical filter 60 includes an outer
skin for
filter housing 58 and a center plug 66. The filter 60 includes single sided
fluted filter
media 48, which is wound around the center plug 66. It can be appreciated that
the
S center plug 66 may be the mandrel upon which the filter media is wound, or
if the
mandrel has been removed, the center orifice may have a cap or cover. The
filter
element 62 has preferably been formed into a conical shape by the methods
described
above. The single sided fluted filter media 48 has alternating upstream closed
end
flutes 34 and upstream opened end flutes 36, as previously shown in Figures 1
and 5.
Viewing from the downstream side, there are alternating downstream closed end
flutes
36 and downstream opened end flutes 34. In a preferred embodiment, the outer
covering for the filter housing 58 includes gaskets 59, for placement of the
filter
element 62 into a housing 54.
Fluid cleaner housing 54, shown in Figure 9, is an existing housing for
automotive air filtering purposes. Preferably, the cleaner housing 54 is
constructed out
of molded plastic. The filter 60 is inserted into the inlet end of the cleaner
housing 54.
The filter 60 is held in place by a compression ring 68 which seals the gasket
59
between the upstream and downstream sections of the cleaner housing 54.
As the flow enters the cleaner housing 54, the conical shape of the upstream
face of the filter 60 forces the fluid from the inside of the conical filter
60 towards the
periphery of the face of the filter 60. This results in relatively even fluid
flow
distribution across the filter. This is accomplished without abrupt
directional changes
which also decreases pressure differential across the filter over the prior
art. After the
flow passes through the filter 60, it exits on the downstream side of the
filter 60 and
passes through the downstream side of the cleaner housing 54. More
particularly, as
the flow approaches the filter 60, it enters through an upstream open end
flute 36. As
the flow passes through the upstream opened end flute 36, it is forced by the
downstream closed end of flute 36 to pass through the wall of the flute 36
into a
downstream open ended flute 34. Particulate material which had been carried
into the
upstream opened end flute 36 will be deposited on the inside wall of the
upstream
opened end flute 36.
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An alternate preferred embodiment of the filter 70 is shown in Figure 10. The -
embodiment shown in Figure 10 has the filter 60 in a stand-alone housing 78.
This
embodiment is configured so that it can be adapted to other existing inline
filter
applications. More particularly, the stand alone housing 78, which is
preferably
constructed of molded plastic, is fitted with an inlet neck 92 and an outlet
neck 94 so
that the stand alone housing 78 can be fitted inline in a fluid stream.
Another alternate embodiment of the present invention, generally designated
80, is shown in Figure 11. A circular or annular vane or bafrle 82 is placed
at the inlet
opening of the filter housing 54. It can be appreciated that the vane 82
provides for
increased fluid flow at the outermost regions of the conical filter element
62, thereby
providing even distribution of fluid flow across the entire conical filter
element 62.
This embodiment, therefore provides for more even distribution of particulate
and
more uniform particulate loading. Hence, the filter element achieves an
extended life.
Referring now to Figures 13 and 14, there is shown a further embodiment of a
filter according to the present invention, generally designated 100. The
filter 100
includes a fivsto-conical shaped filter media element 102 and an associated
filter
housing 104. The filter media element 102 includes an upstream face 100 which
gives
the filter media 102 a frusto-conical configuration. The upstream face 110
includes a
central planar portion 112 and an annular outer sloping portion 114. The
sloping outer
portion is configured to slope outward and away from the central planar
portion which
is substantially transverse to the prevailing upstream flow. In addition, the
filter media
may include a downstream gasket 116 which is configured to seal against the
side of
the housing 104. It can be appreciated that although the filter 100 includes a
frusto-
conical filter media 102, the methods for making the filter remain unchanged
for those
shown in Figures 7 and 8. The filter media 102 may be placed on a frusto-
conical
form, while the sealant is still soft, to impart a frusto-conical shape.
Alternatively, the
filter media 102 may be wound with the mandrel remaining axially stationary
for the
first portion of the winding to provide the planar upstream central face I 12
and then
move axially during winding at the outer portion to provide the outer sloping
portion
of 114.
As shown in Figure 14, the housing 104 includes a substantially straight
housing wall 106. The straight wall 106 provides improved capacity for the
filter
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housing volume. it can be appreciated that with the wall 106 extending
substantially
parallel to the filter flutes and the prevailing direction of the flow, the
wasted space
between the outward sloping wall 106 and the outer portion of the filter is
minimized.
In the embodiment shown in Figure 14, the housing 104 includes an upstream
portion
5 120 and a downstream portion 122. The gasket 116 of the filter media forms a
downstream seal between the housing wall 106 and the filter media 102. The
housing
104 also includes an inlet portion 124 adapting to an upstream duct in an
outlet
portion 126 leading down to the downstream ductwork.
Referring now to Figure 12, there is shown a velocity profile graph across the
10 conical filter 80, shown in Figure 11. Figure 12 shows the varying exit
velocities of
the fluid flow, represented along the Y-axis, in relation to the fluid flow's
position as it
exits the filter, represented along the X-axis. As is evidenced by the graph,
fluid flow
across a conical filter of this type has a relatively uniform velocity profile
providing
the improvements and advantages described herein.
It is to be understood, however, that even though numerous characteristics and
advantages of the present invention have been set forth in the foregoing
description,
together with details of the structure and function of the invention, the
disclosure is
illustrative only, and changes may be made in detail, especially in matters of
shape,
size and arrangement of parts within the principles of the invention to the
full extent
indicated by the broad general meaning of the terms in which the appended
claims are
expressed.
