Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02678454 2009-07-20
FLUID FILTER WITH PRESSURE RELIEF VALVE
Field of the Invention
[0001] The present invention relates to fluid filters, and more
particularly, a fluid filter
having a pressure relief valve to provide an accurate visual indicator as to
the remaining life of
a filter element.
Background of the Invention
[0002] It is well known t.o utilize fuel filter assemblies to filter
fuel for a combustible
engine of a motor vehicle. Such fuel filter assemblies comprise a variety of
different
orientations of the fuel filter assembly. For example, it is known to utilize
sideways,
downwardly, and upwardly mounted canisters having a paper filter media
enclosed in the
canister. With respect to upwardly mounted fuel assemblies, prior art
filtration devices have
been known to. draw fuel into the filter assembly by use of a pump on the
outlet side of the
filter assembly. The fuel is directed downward into a lower chamber of the
filter assembly
wherein the fuel flow proceeds upward into an upper filter chamber of the
filter assembly. The
fuel may then be contained and sealed by a transparent filter cover or closure
and a filter
mount which may separate the lower chamber from the upper chamber.
[0003] Within the filter chamber of the filter assembly, the filter
assembly may provide
a filter canister comprised of a filter media circling a central filter tube
that is contained by
filter end caps at the top and bottom of the filter media. The end caps are
sealed to the edges
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of the filter media to preclude any possible leak paths at the ends of the
filter canister. The
filter media typically comprises a porous paper material that may be pleated
or concentrically
wound so as to direct the fluid through the filter media. The filter media
removes and retains
undesirable contaminants within and on the media.
L3004] As fluid enters the filter chamber, the fuel level rises and
passes through from
the outside to the inside of the filter media. The fuel then flows downward
into a central
passage located along the central axis of the canister. The central passageway
is in
communication with a fuel outlet wherein the fuel passes outwardly from the
filter assembly.
[0005] During the filtering process, the fuel is either drawn into the
filter chamber by a
vacuum or pushed into the filter chamber by pressure until the fuel finds a
path throuethe
filter media. As the fuel flows through the filter, dirt and other
contaminants larger than the
porous openings in the filter media, are trapped and retained by the filter
media. These
contaminants plug or clog the porous holes in the filter media and restrict or
close the paths
used by the flowing fuel. The fuel is then forced to seek other open and less
restrictive flow
openings which are available above the level of the fuel by climbing the
height of the filter and
accessing the clean areas of the filter media. This process of clogging and
climbing continues
until the filter media is completely immersed in the flowing fuel.
[0006] Even though the filter media may be completely immersed in the
flowing fluid,
the incoming fuel continues to pass through the filter media. It is not until
the filter media
becomes greatly clogged that the filter media needs to be replaced. This is a
problem since the
user generally views the height of the fuel in the filter chamber to see if
the filter media is
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clogged. If the filter media is completely immersed in fuel, the user
generally believes that the
filter media needs to be replaced. Therefore, this type of system may lead to
premature
-replacement of the filter media.
[0007] It would be desirable to provide a fuel filter assembly that
provides an accurate
indication as to the remaining usefulness of the filter media.
Summary of the Invention
[0008] The present invention provides a fluid filter assembly
that provides an accurate
indication of the remaining usefulness of a filter element. The present
invention provides a
vertical, transparent housing having a fuel inlet for communicating fluid into
the housing and a
fluid outlet for communicating fluid downstream of said housing. A filter
element is disposed
within the housing between the fluid inlet and the fluid outlet for filtering
the fluid. A means
for maintaining and relieving a predetermined level of pressure across the
filter element
provides an accurate visual indicator as to whether the filter element needs
replacement.
[0009] Preferably, the maintaining and relieving means provides a
divider that is
connected to the filter element and extends between a housing wall and an
unfiltered side of
the filter element. The divider divides the housing into an outer region and
an inner region,
wherein the outer and inner regions are in communication at a lower portion of
the housing.
A relief valve is in communication with a filtered side and the unfiltered
side of the filter
element and is located in the top of the filter element in the outer region of
the housing. The
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relief valve opens when the pressure across the filter element exceeds the
predetermined
pressure level thereby raising the level of fluid in the outer region of the
housing and indicating
that the filter element needs replacement. A segment of filter media may be
adjacently mounted
to the relief valve to filter any unfiltered fluid that passes through the
relief valve to the filtered
side of the filter element.
[0010] Alternatively, the maintaining and relieving means may provide a
restrictive
filter media integrally connected to the filter element. The restrictive
filter media prevents the
flow of fluid through the restrictive filter media until the pressure across
the filter element
reaches the predetermined pressure level thereby causing the fluid in the
housing to rise and
indicating that the filter element needs replacement.
[0010a] The present invention also provides a filter cartridge,
comprising:
a substantially cylindrical filter media adapted to allow fluid to pass from
an
exterior of said filter media to an interior of said filter media, said filter
media having an upper
end and a lower end;
a divider positioned adjacent to said exterior of said filter media, the
divider
having an upper end and an open lower end, wherein said upper end is connected
to said upper
end of said filter media; and
a pressure relieving structure disposed at said upper end of said filter
media, and
said pressure relieving structure opening when a predetermined pressure level
is established
across said filter media to maintain said predetermined pressure across said
filter media.
[0010b] The present invention further provides a filter
cartridge, comprising:
a substantially cylindrical filter media adapted to allow fluid to pass from
an
exterior of said filter media to an interior of said filter media, said filter
media having an upper
end and a lower end;
a top cap disposed at said upper end of said filter media and connected to
said
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filter media;
a bottom cap disposed at said lower end of said filter media and having an
opening adapted to receive a fluid outlet;
a divider positioned adjacent to said exterior of said filter media, said
divider
having an upper end connected to said top cap and an open lower end, and said
divider defining
an interior region between the outside of said filter media and an inner
surface of said divider
and an exterior region adjacent to the outer surface of said divider, wherein
said interior region
and said exterior region are in communication at said open lower end of said
divider; and
a pressure relieving structure disposed at an upper end of said filter media,
and
said pressure relieving structure opening when a predetermined pressure level
is established
across said filter media, said pressure relieving structure allowing said
fluid and/or air/vapor to
pass therethrough when the pressure across said filter media reaches a
predetermined level,
wherein the release of said pressure allows the level of said fluid to rise
within a housing of the
fluid filter assembly.
[0010c] The present invention still further provides a filter
cartridge, comprising:
a substantially cylindrical filter media adapted to allow fluid to pass from
an
exterior of said filter media to an interior space at least partially defined
by said filter media;
a top cap disposed at said upper end of said interior space and connected to
said
filter media;
a bottom cap disposed at said lower end of said interior space and having an
opening adapted to receive a fluid outlet; and
a divider positioned adjacent to said exterior of said cylindrical filter
media, said
divider having an upper end connected to said top cap and an open lower end,
and said divider
defining an interior region between the outside of said cylindrical filter
media and an inner
surface of said divider and an exterior region adjacent to the outer surface
of said divider,
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wherein said interior region and said exterior region are in communication at
said open lower
end of said divider,
said top cap having a pressure relieving structure that opens when a
predetermined pressure level is established across said filter media, said
pressure relieving
structure allowing said fluid and/or air/vapor to pass theretluough when the
pressure across said
filter media reaches a predetermined level, wherein the release of said
pressure allows the level
of said fluid to rise within a housing of the fluid filter assembly.
Brief Description of the Drawings
[0011] The description herein makes reference to the
accompanying drawings wherein
like referenced numerals refer to like parts throughout several views and
wherein:
[0012] Fig. 1 is a schematic drawing showing the fluid flow path and
the normal rising
fluid path of a prior art fiiel filter assembly.
[0013] Fig. 2 is a schematic drawing showing the rising fluid level in
the fluid filter
assembly of the present invention.
[0014] Fig. 3 is a schematic drawing showing a segment of filter media
being utilized
above a relief valve of the present invention.
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[0015] Fig. 4 is a schematic drawing showing a segment of filter
media being utilized
underneath the relief valve of the present invention.
[0016] Fig. 5 is a schematic drawing of a hang down fluid filter
assembly of the present
invention.
[0017] Fig. 6 is a schematic drawing showing a restrictive media being
utilized as a
relief valve in the fluid filter assembly of the present invention.
[0018] Fig. 7 is a bottom view of the filter element of the
present invention.
[0019] Fig. 8 is a sectional view of the filter element of the
present invention taken in
the direction of arrows 9-9 in Fig. 8.
[0020] Fig. 9 is an exploded view of the relief valve shown in the top
of the filter
element of the present invention.
[0021] Fig. 10 is a sectioned perspective view of the relief valve
shown in the top of
the filter element of the present invention.
Description of the Preferred Embodiment
[0022] Referring to the drawings, the present invention will now
be described in detail
with reference to the preferred embodiment.
[0023] Fig. 2 shows a fluid filter assembly 10 of the present invention
in its preferred
form. The fluid filter assembly 10 is best suited for filtering and processing
diesel fuel, but the
fluid filter assembly 10 may also be utilized with other fluids, such as
.gasoline, oil, water,
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antifreeze, etc. The fluid filter assembly 10 is mounted vertically upright
and provides a
closed housing 12 having a lower fluid storage chamber 16, and an upper filter
chamber
17, the outer housing of which is preferably made of transparent plastic. A
fluid inlet 14
is in communication with the lower fluid storage chamber 16, which is in
communication
with the upper chamber 17 through a passageway 15. A filter element 20 is
housed
within the upper chamber 17 of the housing 12 for filtering a fluid 19 to a
fluid outlet 18.
The fluid inlet 14 delivers fluid 19 into the housing 12 so that the fluid 19
may pass
through the filter element 20 and out the fluid outlet 18. A relief valve 38
mounted in the
top of the filter element 20 opens when the pressure level across the filter
element 20
reaches a predetermined level. A relief valve filter 40 filters fluid 19 that
passes through
the relief valve 38. Preferably, the relief valve filter 40 is mounted below
the relief valve
38, as shown in Fig. 4, but alternatively, the relief valve filter may be
mounted above the
relief valve 38, as shown in Fig 3.
[0024] To filter contaminants from the fluid 19, the filter element 20
is fabricated
from a pleated porous paper material. The filter element 20 encircles a
central filter tube
22 and is contained by a top and bottom end cap 24, 26, respectively, as seen
in Figs. 2
and 7-11. The top and bottom end caps, 24, 26 are sealed to the edges of the
filter
element 20 to preclude any possible leak paths at the ends of the filter
element 20. A
flexible seal 28 is provided on the bottom end cap 26 of the filter element 20
to create a
seal between the central filter tube 22 and an inner core 43 of the filter
element 20 and
ensure that unfiltered fluid 19 does not leak into or escape through the fluid
outlet 18.
The filter element 20 is preferably pleated or concentrically wound but may
also be
arranged in any of the ways known to one familiar with
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filtration construction so as to direct the fluid 19 through the filter
element 20. In addition, the
filter element 20 may be fabricated from a hydrophobic filter material to
filter out water from
the fluid 19.
{0025] The portion of the housing 12 between the filter element 20 and
an outer wall
37 of the upper filter chamber 17 of the housing 12 is preferably divided by a
substantially
frusto-conical divider 30. The divider 30 has a top portion 32 that is either
integrally or
sealedly connected to the top end cap 24 of the filter element 20. The divider
30 also has a
bottom portion 33 that extends downward toward the bottom of the filter
element 20, while
also tapering or flaring outward away from the filter element 20. It should be
noted that the
present invention is not limited to a frusto-conical divider 30, but rather,
the divider may also
be substantially cylindrical wherein the bottom portion of the divider may
extend downward
substantially parallel to the filter element 20. In both embodiments, the
divider 30 essentially
divides the upper chamber 17 of the housing 12 into an inner portion or
regioin 34 and an
outer portion or region 36. The inner portion 34 is the space contained
between the outside or
unfiltered side of the filter element 20 and the inner surface of the divider
30. The outer
portion 36 is the space contained between the outer surface of the divider 30
and the inner
surface of the outer wall 37 of the upper chamber 17 of the housing 12. The
inner and outer
portions 34, 36 remain in fluid communication at the bottom portion of the
upper filter
chamber 17 of the housing 12.
[0026] In order to maintain and relieve the pressure in the
upper chamber 17 of the
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housing 12, a relief valve 38 is mounted in the top end cap 24 of the filter
element 20. The top
end cap 24 is fabricated from a thin metallic material having a shape
complementary to the top
of the filter element 20. The top end cap 24 has a substantially circular
configuration with
sidewalls 39 that extend downward from its periphery to sealingly connect to
and cover the
top of the-filter element 20. The top end cap 24 also has a centrally located
recessed portion
41 which is received by and complementarily engages the inner core 43 of the
filter element
20.
[0027] The recessed portion 41 of the top end cap 24 is formed by two
layers of thin
metallic material. A first inner layer 45 is integrally connected to the
sidewalls 39 and the
portion of the top end cap 24 that extends over the top of the filter element
20. A second
outer layer of the recessed portion 41 is formed by a substantially
cylindrical cup that is
connected to and complementarily engages the inner layer 45 of the recessed
portion 41. The
inner layer 45 of the recessed portion 41 has a raised portion 49 relative to
the outer layer 47.
The outer layer 47 has four apertures 51 that extend therethrough and align
directly under the
raised portion 49 of the inner layer 45 of the recessed portion 41. A sheet of
filter media 53
lies between the inner layer 45 and the outer layer 47 of the recessed portion
41 so as to
cover the four apertures 51 extending through the otter layer 47.
[0028] The raised portion 41 of the inner layer 45 provides two
apertures 55, 57
extending therethrough. The larger of the two apertures 55 receives a flexible
valve member
58 having an inverted mushroom-shaped configuration. The stem portion 59 of
the
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mushroom-shaped configuration is disposed within the larger aperture 55. The
head portion
61 of the flexible member 58 extends across the underside of the raised
portion 49 of the inner
layer 45 such that the head portion 61 of the flexible member 58 covers the
smaller aperture
37. The smaller aperture 57 acts as a port such that when the pressure level
across the filter
element 20 reaches a predetermined level, the head portion 61 of the flexible
member 58 flexes
away from the smaller aperture 57 thereby allowing fluid 19 and/or air/vapor
from the
unfiltered side of the filter element 20 to pass through the smaller aperture
57. Fluid 19 will
only pass through the smaller aperture 57 after all of the air/vapor has first
passed through the
smaller aperture 57. The fluid 19 and/or air/vapor passes through the sheet of
filter media 53
and through the four apertures 51 in the outer layer 47 of the recessed
portion 41 to the
filtered side of the filter element 20. Although the patentable subject matter
may be limited to
a relief valve 38 having the structure defined above, Applicants consider the
invention to
include any relief valve 38 having a structure that provides for the release
of fluid 19 and/or
air/vapor at a predeteimined pressure level.
[0029] The relief valve 38 is normally closed until the pressure level
across the filter
element 20 exceeds a predetermined level. When the relief valve 33 is closed,
the air/vapor
within the outer portion 36 of the housing 12 is trapped thereby forcing the
fluid level in the
outer portion 36 to be lower than the fluid level in the inner portion 34.
This occurs because
as long as the filter element 20 is not clogged, air/vapor and fluid 19 within
the inner portion
34 will pass through the filter element 20 at a pressure less than the
pressure level in which the
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relief valve 38 is to open. Once the pressure across the filter element 20
exceeds the
predetermined level due to the filter element being sufficiently clogged, the
relief valve 38
opens and allows air/vapor and/or fluid 19 to pass from the outer portion 36
of the housing 12
to the inner core 43 of the filter element 20.
[0030] In a secondary embodiment of the fluid filter assembly 10', a
restrictive filter
media section 42 of the filter media 20' is either integrally formed on the
top of the filter media
20' or is attached to the upper portion of the filter media 20', as shown in
Fig 6. The
restrictive section 42 of the filter media 20' acts in the same manner as the
relief valve 38 and
the relief valve filter 40 of the preferred embodiment, but the secondary
embodiment does not
require the divider 30. The restrictive section 42 of the filter media 20'
only allows air/vapor
and/or fluid 19 to pass through the restrictive section 42 once the pressure
level across the
filter element 20 exceeds a predetermined level. This ensures that the fluid
level within the
housing 12 will remain at a level below the restrictive filter media 42. Once
the predetermined
pressure level is reached, air/vapor and/or fluid is allowed to pass through
the restrictive filter
media 42 thereby raising the fluid level and providing a visual indicator that
the filter element
20' needs replacement.
[0031] In yet another embodiment of the present invention, a divider
30" and a relief
valve 38" may be utilized in conjunction with a hang down fluid filter
assembly 10", as shown
in Fig. 5. The structure in this embodiment is similar to that of the
preferred embodiment in
that the divider 30" is sealedly connected to a top end cap 24". The divider
30" extends
CA 02678454 2009-07-20
downward along the bottom portion of the filter element 20 while flaring
outward from the
filter element 20. A relief valve filter (although not shown in Fig. 5 but
similar to that shown
in Figs. Band 4) is mounted in a portion of the central filter tube 22. The
relief valve filter is
incorporated with the relief valve 38" to prevent any unfiltered fluid 19 from
entering fluid
outlet 18". The relief valve 38" in the hang down fluid filter assembly 10"
works in the same
manner as the preferred embodiment. The divider 30" forms an outer portion 34"
and an
inner portion 32" of the housing 12" wherein the trapped air in the outer
portion 34" forces
the fluid level in the outer portion 34" to be lower than the fluid level in
the inner portion
32". This allows the filter element 20 to become completely clogged before
reaching the
predetermined pressure level that will open the relief valve 38". Once the
relief valve 38"
opens, air/vapor passes through the relief valve 38" thereby allowing the
fluid level in the
outer portion 34" to rise and provide a visual indicator that the filter
element 20 needs
replacement.
[0032] In operation, the prior art device functions as depicted in
Figs. 1. Fluid 19
enters the fluid inlet 14 of the fluid filter assembly 10 and accumulates
within the lower
chamber 16 of the housing 12. Fluid flows through the passageway 15 leading to
the upper
filter chamber 17 wherein an unfiltered fluid level is established within the
upper filter chamber
17. The fluid 19 is drawn into the filter chamber 17 by vacuum (as most
commonly occurs in
diesel fuel filters) or forced by low pressure (as seen in oil, antifreeze or
many other filters)
until it finds a path through the filter element 20. As the filter element 20
becomes partially
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clogged, the restriction increases temporarily overcoming the surface tension
of fluid covering
the unused pores of the filter 20 element and causing a temporary flow of
air/vapor through
the filter element 20. As the air/vapor passes, it creates a void on the
outside of the filter
element 20, and the fluid level rises to fill the void. The new fluid level
allows flow through
clean and unused pores of the filter element 20, and the restriction through
the filter element
20 reestablishes itself at a fluid level as previously described. Once the
fluid level establishes
itself, the surface tension of the fluid 19 across the remaining pores of the
filter media 20
prevents the flow of air/vapor through the filter element 20 until, once
again, the restriction
increases to a level in which air/vapor is forced through the filter element
20. This process
continues as dirt and other contaminants in the fluid 19, larger than the
openings in the filter
element 20, are trapped and retained by the filter element 20 as the fluid 19
passes through the
filter element 20. These contaminants plug or clog the holes in the filter
media 20 and restrict
and/or close the paths used by the flowing fluid 19. The fluid 19 is forced to
seek other open
and less restrictive fluid openings that are above the level of the fluid 19,
and therefore, the
fluid 19 climbs up the height of the filter element 20 and uses the clean
areas of the filter
element 20. The process of clogging and climbing continues until the filter
element 20 is
completely immersed in the flowing fluid 19. When the fluid level reaches the
top of the upper
filter chamber 17, this has generally been a visible indication to the user to
change the filter
element 20. The problem with changing the filter element 20 at this point is
that the filter
element 20 still allows for the passage of fluid 19 through the filter element
20 even when the
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fluid level has risen to the top of the filter chamber 17. Therefore, if the
filter element 20 is
changed immediately upon the fluid level rising to the top of the filter
chamber 17, then the
filter element 20 is being replaced prematurely.
[0033] During the operation of the preferred embodiment of the present
invention,
fluid 19 enters the fluid filter assembly 10 and the upper filter chamber 17
in the same way as
described in the prior art. However, by employing the divider 30 and
incorporating the preset
relief valve 38 in the top end cap 24, the fluid level can be made to rise
approximately in
proportion to the plugging rate of the fuel element 20. This gives an accurate
visual indicator
as to the remaining life of the filter element 20. In so doing, the incoming
fluid 19 and
air/vapor initially behave as similarly described in the prior art. When the
fluid level
approaches the bottom of the divider 30, the fluid 19 continues to rise
between the filter
element 20 and the inside surface of the divider 30, which was previously,
defined as the inner
portion of the housing 12, but the fluid 19 does not rise between the outer
surface of the
divider 30 and the outer wall of the housing 12, which was previously defined
as the outer
portion of the housing 12. This is because the trapped air/vapor in the outer
portion 36 of the
housing 12 prevents the rise of fluid 19 into the outer portion of the housing
12.
[0034] As to the inner portion 34 of the housing 12, fluid 19 and
air/vapor move
through the filter element 20 in a usual manner. The fluid level continues to
rise between the
filter element 20 and the inside surface of the divider 30 as the filter
element 20 becomes more
clogged. This continues until the fluid 19 has risen to the full or nearly
full height of the filter
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element 20, as previously described. Once the filter element 20 is completely
saturated, the
pressure differential across the filter element 20 begins to increase with the
increased clogging
of the filter element 20. Once this pressure differential reaches a
predetermined level,
preferably 5" Hg, the relief valve 38 may open, and vapor/air may flow through
the relief valve
38 while fluid flows through the filter element 20 since both present the same
amount of
resistance to flow. As the pressure differential across the filter media 22
begins to exceed the
5" Hg point, the relief valve 38 becomes the preferred flow path since its
pressure differential
is fixed at 5" Hg. Since air/vapor is closest to the relief valve 38, the
air/vapor flows through
the relief valve 38 first, and the fluid 19 follows. The fluid level begins to
rise in the outer
portion 36 of the housing 12, thereby providing a visual indicator to the
operator that the filter
element 22 is plugged. The relief valve filter 40 provided in the fluid path
of the relief valve
38 ensures that the fluid 19 that passes through the relief valve 38 is
filtered. Once the user
sees that the fluid level in the outer portion 36 of the housing 12 has risen
to the top of the
upper filter chamber 17, the user knows to replace the filter element 20.
[0035] In operation,. the secondary embodiment, as depicted in Fig. 6,
works in a
similar manner as described in the preferred embodiment. The fluid level rises
within the filter
chamber 17, until it reaches the restrictive filter media 42 on the filter
media 20. When the
fluid level reaches the restrictive media 42, the pressure differential across
the filter media 20'
must rise to a preferred level of 5" Hg in order for the air/vapor and fluid
19 to pass through
the restrictive media 42. The fluid level stops at a point just below the
restrictive media 42
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level. At that point, air/vapor and fluid 19 pass through the restrictive
media 42, thus
allowing the fluid level to rise within the filter chamber 17 of the fluid
filter assembly 10' . The
user may then use the risen fluid level as an indicator that the filter media
20' needs to be
replaced.
10036] In operation, the alternative embodiment depicted in Fig. 5
works in exactly the
same manner as described in the preferred embodiment. The only difference in
the
embodiment depicted in Fig. 5 is that the housing 12" is upside down, but the
fluid level
responds in the same manner as described in the preferred embodiment.
[0037] While the invention has been described in connection with what
is presently
considered to be the most practical and preferred embodiment, it is to be
understood that the
invention is not to be limited to the disclosed embodiments, but on the
contrary, it is intended
to cover various modifications and equivalent arrangements included within the
scope of
the appended claims, the scope is to be accorded the broadest interpretation
so as to encompass
all such modifications and equivalent structures as is permitted under the
law.
[0038]
