Note: Descriptions are shown in the official language in which they were submitted.
2~ a7726
- FUEL/WATER SEPARATOR FILTER WITHOUT FLOW
DIVERTERS AND METHOD OF MAKING SAME
Background of the Invention
1. Field of the Invention
This invention relates generally to a replaceable filter assembly for a
spin-on coalescing filter in which the filter element is suspended at a
clearance from the bottom of the housing without the use of flow
diverters, springs, washers, or the like, and more particularly, to an
improved replaceable filter assembly.
2. Description of Related Art
Conventional spin-on fuel filters are used to separate contaminants,
such as unwanted water, from fuel systems. The typical spin-on fuel filter
utilizes the centripetal forces of the fluids to separate water from fuel oil,
lubricating oil, diesel fuel, or the like. The known fuel filter has a
cylindrical outer container in which an annular or cylindrical filter
element is disposed coaxially. The unfiltered fuel enters the top portion of
the container through an upper plate having a number of holes. The fuel
then flows radially inward through the filter element to the middle of the
filter where there is a threaded filter outlet concentric with the
longitudinal axis of the filter. Alternatively, the filter inlet and outlet may
be reversed such that the flow is radially outward through the filter
element. In either event, water droplets fall to the bottom of the filter
container where they are collected in a bowl removably connected thereto
21 87726
by threads. A typical spin-on filter of this type is described in U.S. Patent
No. 4,6.26,348 to Stone, for example.
There have been several different techniques for mounting the
filter element inside the filter. In all cases, however, it is necessary to seal5 the filter element to the upper plate through which the fuel enters, in
order to isolate the inlet and outlet flow paths.
In one known method for mounting the filter element, a
compression spring is disposed between the bottom of the filter element
and the base of the outer container. The filter is thereby urged against the
10 upper plate by the spring. Such an assembly is described, e.g., in U.S.
Patent Nos. 3,434,601 to Barth et al., 4,253,954 to Midkiff et al., and 4,292,179
to Stone et al. This method is considered disadvantageous for several
reasons. First, the provision of the compression spring makes the filter
more difficult to assemble and more expensive, reducing the mass-
15 producibility of the device. Second, the provision of the spring or otherbiasing means takes up vital space inside the filter, thus reducing the
efficiency of the filter. The biasing means also makes replacement of the
filter more difficult. Finally, in many situations, the use of a biasing
means necessitates the provision of flow diverters to help channel the
20 flow of the fuel and/or removed water. These flow diverters, which can
take the form of ribs, make the machining process more complex and
expensive.
An alternative method of securing the filter onto the filter head by
supporting the filter at its bottom is disclosed in U.S. Patent No. 4,740,299
25 to Popoff et al. In several of the embodiments disclosed in this patent, a
plastic annular threaded ring is provided in a bottom portion of the outer
housing. In general, the ring spaces the filter element from the bottom of
the housing, has threads for attaching the collection bowl to the filter, and
may also direct contaminant flow into the collection bowl. In one specific
30 embodiment of Popoff et al., the bottom end cap of the filter rests on top of the threaded ring and the collection bowl engaged therewith. As the
21 ~7726
collec~ion bowl is threaded onto the ring, the collection bowl abuts against
a seal E?rovided in the lower end cap of the filter; the lower end cap has
radial ridges forming contaminant flow paths to the collection bowl (see
Fig. 6 of Popoff et al.). In another embodiment, the annular threaded ring
5 is a support ring provided with outwardly facing threads for engaging the
inwardly facing threads on a collection bowl. The support ring also has
radial ribs projecting upward from the ring, which support the bottom of
the~lower end cap and form contaminant flow channels between the ribs
(see Fig. 11). Use of such a spacer ring reduces the area available for
10 contaminant flow and water collection, and thereby reduces the efficiency
of the filter. Moreover, even if radial ribs are added to the ring to provide
the necessary flow paths, these ribs increase the cost and complexity of the
machining the filter.
A filter that suffers from similar disadvantages as Popoff et al. is
15 described in U.S. Patent No. 5,362,389 to Hardison et al. In Hardison et al., the outer housing is provided with two turned-in portions, one near the
top and the other near the bottom. Disposed in abutment with the turned-
in portions are ring-shaped members which have inwardly facing threads.
The upper ring-shaped member threads onto the filter head, and the
20 containment bowl threads onto the lower ring-shaped member. The filter
end caps are provided with radial ribs which fit into grooves in the ring-
shaped members. These ribs, like the ribs in Popoff et al., form flow
channels therebetween. Thus, the upper ring-shaped member secures the
upper end cap of the filter onto the filter head when they are threaded
25 onto the filter head, and the lower ring-shaped member secures the lower
end cap of the filter from below.
Like Popoff et al., the arrangement in Hardison et al. fixes the filter
element at both ends and provides ribs for structural and flow diversion
purposes. Hardison et al., shares some of the problems associated with
30 Popoff et al., and suffers from additional deficiencies. First, the machining required to manufacture the various annular members with both radial
21 87726
ribs an,d threads is very complex. Complex machining increases both the
time and the cost required to produce the element. Moreover, the ring-
shaped members and the filter end caps of Hardison et al. are solely in
contact where the radial ribs of the latter fit into the grooves of the former
5 The compressive load produced when the ring-shaped members are
threaded onto the filter head and the collection bowl is not evenly
distributed to the filter end caps, but instead is transmitted only at the ribs,thereby localizing the compressive load and increasing the risk of failure.
Furthermore, by providing ribs as flow diverters, more of the internal
10 space of the filter housing is occupied, and therefore less fuel can be
filtered or less space is available for water collection.
Another method of mounting the filter element involves fixing the
filter element in a cantilever fashion, thereby leaving a clearance between
the bottom of the filter element and the inner floor of the container.
15 Different ways of suspending the filter are described in U.S. Patent Nos.
3,485,380 to Offer et al. and 5,171,430 to Beach et al., for example.
In Offer et al., a flange of the filter end cap is held tightly against the
upper seal, which is in turn held tightly against the top plates. The flange,
seal, and plates are held together by a ratchet retaining ring. The ring is
20 placed around a tubular neck, which protrudes from the upper plate, after
the seal and flange are attached. The ratchet ring has radially inwardly
extending fingers which dig into the tubular neck after the ring is placed
on the neck, so as to positively hold the filter element in position against
the seal, and positively compress the seal. The ring is preferably made of
25 spring steel. In other words, Offer et al. employs essentially a radial leaf
spring to secure the filter end cap to the seal and the seal to the plate. This
technique is not desirable because the machining of this ratchet retaining
ring is difficult, and the forcing of it into place makes the assembly process
slow and expensive. In addition, Offer et al. relies solely upon the
30 resilience of the ratchet ring to hold the flange, seal, and plates together.
21 87726
Beach et al. discloses various filters in which the filter shell is
formed, from plastic by both injection and blow molding. The upper end
cap of the filter element has tabs which rest on a shoulder that projects
from the interior of the filter shell. The filter is thus supported in a
5 cantilever manner by the shoulder formed in the shell. Since the outer
container in Beach et al. is made out of plastic, it is difficult to manufacturethe outer container to have the inwardly projecting support shoulder. In
an alternative embodiment in Beach et al., the filter element is secured to
the bottom of the outer container with an adhesive or similar means.
The foregoing review of prior art demonstrates that there is a need
for a replaceable fuel filter assembly that is.less expensive and easier to
manufacture than prior filters, and avoids the use of flow diverters,
washers, or springs to increase the efficiency and capacity of the filter,
while at the same time facilitating replacement of spent filters.
15 Summary of the Invention
The invention solves the above and other problems, and avoids the'
disadvantages and drawbacks of the above-described art by providing a
filter element supported solely in a cantilever fashion by a support
member, thereby leaving a clearance between the base of the outer housing
20 and the lower end cap of the filter element. By utilizing this type of
structure, the invention maximizes the space available for filtration and
water collection, and is thus more efficient than previous filter designs.
The invention does not require the provision of flow diverters, washers,
springs, or the like, thereby simplifying and reducing the cost of mass
25 production.
More specifically, these features are achieved by providing a filter
assembly with a generally cylindrical metal housing having a top portion
and a bottom portion. A metal plate may be welded to the top portion of
the container for added strength. A hole in the top portion of the housing
30 communicates with an interior portion of the filter assembly, and has
- ; 21 87726
threads at its inner surface for replaceably mounting the filter assembly. A
filter e}ement supported inside the housing includes an upper end cap and
a lower end cap fixedly attached to a filter medium. An inner fuel
chamber is disposed inside the filter element, while an outer fuel chamber
5 is disposed between the filter element and the metal housing. A support
member is attached between the top portion of the container and the
upper end cap, thereby suspending the filter element from the metal plate
at a clearance from the bottom of the housing. No elements are disposed
in the clearance spacc bctwccn thc lowcr cnd cap of thc filtcr and thc basc
10 of the outer housing. The support member also seals the hole and inner
fuel chamber from the outer fuel chamber.
In a first embodiment of the invention, the support member is
chemically bonded between the top portion of the metal housing and the
upper end cap. The support member preferably may be made of rubber or
15 similar material such as nylon, plastic, or open-celled rubber foam. The
hole in the top portion of the housing may be formed by a downwardly
depending cylindrical projection of the metal plate. A surface of the
support member may be chemic~lly bonded to a surface of the metal plate
in a position radially outward from the cylindrical projection. This
20 embodiment is superior to the method disclosed in Offer et al., for
example, because chemical bonding is less expensive than machining and
applying a retaining ring. Moreover, assembly of the invention is made
easier by using a chemical bonding agent or adhesive especially suited for
the filter environment of the invention, e.g. ethyl cyanoacrylate, rather
25 than having to cast the ring and then force the ring into place. The
invention thus greatly enhances the mass-producibility of the product.
In a second embodiment of the invention, the support member may
be mechanically locked between top portion of the housing and the upper
end cap. The support member may form a mechanical screw lock made
30 from metal or plastic having outwardly facing threads engaging the
inwardly facing threads formed on the inner surface of the hole in the top
21 ~7726
portion of the container. The upper end cap also has inwardly facing
threads, disposed on its inner circumferential surface. These threads also
engage the outwardly facing threads of the screw lock. During assembly,
the screw lock may have a chemical applied to the threads, so that the filter
5 may be installed or removed without the screw lock being unthreaded
from the housing or upper end cap. By providing this type of structure,
relative motion of llle plale and top end cap (witll respcct to tlle screw
lock) is prevented.
In a third embodiment of the invention, the support member may
10 be both chemically bonded and mechanically attached to the top portion of
the housing, while the upper end cap may be mechanically attached to the
support member. The support member preferably may be made of a
resilient material such as rubber, nylon, plastic or open-celled rubber foam.
As in the first embodiment, the hole in the top portion of the housing
15 may be formed by a downwardly depending cylindrical projection of a
welded, metal plate. At a lower portion of the cylindrical projection, the
diameter of the projection increases, so as to form a lip extending radially
outwardly. The lip positively engages the support member and holds the
resilient element support onto the plate. A chemical bonding agent of the
20 invention may be applied between the support member and the plate. The
support member may be provided with a recess for receiving part of the
upper end cap. The recess may be smaller than the inner portion of the
upper end cap, so as to form an interference fit when the end cap is press-
fit into the element support. A chemical bonding agent also may be
25 applied to the recess before the end cap is press-fit therein.
An advantageous method of making the various embodiments of
the invention also is disclosed herein.
21 ~7726
Brief Description of the Drawings
Fig. 1 is a partial sectional view of a first embodiment of the
invention illustrating a filter element suspended in a filter housing by a
support member chemically bonded to the filter element and housing.
Fig. 2 is a partial sectional view of a second embodiment of the
invention illustrating a filter element suspended in a filter housing by a
su~2port member mechanically locked to the filter element and housing.
Fig. 3 is a partial sectional view of a third embodiment of the
invention illustrating a filter element suspended in a filter housing by a
support member employing both chemical bonding and mechanical
locking techniques.
Fig. 4 is an enlarged view of portion IV of Fig. 1 better illustrating
the support member of the invention.
Fig. 5 is an enlarged sectional view of the support member of the
Fig. 3 embodiment.
Detailed Description
Referring to Fig. 1, the first embodiment of the invention will be
described. The filter design has an outer housing that may be constructed
from a drawn metal container 2 and an upper plate 5 made from stamped
metal. Appropriate metals include cold rolled steel and the like. Plate 5 is
welded to a top filter cover having an annular recess (not shown) in which
a filter gasket 20 is retained in a conventional manner. The cover and
filter housing are connected together by a double seamed seal (not
explicitly shown) typical of those employed in conventional oil filters. A
rubber element support 6 is chemically bonded, e.g., by an adhesive of the
type discussed below, to at least the bottom of plate 5 near a cylindrical
projection 9 which downwardly depends from plate 5. Projection 9 forms
a central opening 30 having inward facing threads 7 formed on its inner
surface for screwing the filter on and off of the engine.
21 ~7720
The upper and lower end caps 10, 11 of the filter element 3 are
preferakly made from drawn metal and are fixedly connected to filter
element 3 by e.g., using any well known adhesive, such as plastisol.
Element support 6 is provided with two mounting surfaces 6-1 and 6-2 for
connecting the support to the housing and filter element. Specifically,
upper end cap 10 is ch~mil ~lly bonded to mounting surface 6-1, while
element support 6 is chemically bonded to plate 5 at mounting surface 6-2.
Asbest shown in Fig. 4, mounting surface 6-1 may take the form of a
squared-off groove comprising two essentially flat annular surfaces 6-la, 6-
lb, which are orthogonal to one another. The groove receives an inner
portion of the upper end cap and may be connected to the end cap at one or
both of the mounting surfaces 6-la, 6-lb by an adhesive, described
subsequently, especially suited for the filter environment of the invention.
Mounting surface 6-2 includes a top substantially flat annular surface 6-2a
and a cylindrical surface 6-2b; surface 6-2b snugly receives the projection 9,
thus positioning a portion of the bottom surface of plate 5 (adjacent to or
near projection 9) opposite mounting surface 6-2a. Adhesive of the type
described below also may be applied to fixedly connect the support 6 to the
plate 5 at one or both of the surfaces 6-2a, 6-2b.
In this way, element support 6 suspends the filter element 3 from
plate 5 and supports it in the housing. Filter element 3 is thus suspended
from filter cover 5 in a cantilevered manner leaving a clearance space 12
between bottom end cap 11 and the bottom of filter container 2 for water
and contaminants to flow to the collection bowl. There are no springs,
washers, or other elements disposed between the bottom of the filter
container and the filter element. By leaving enough clearance in the space
12 beneath the filter element 3, the volume of outer fuel chamber 40 may
be increased significantly, and the filter operates more efficiently.
Element support 6 also serves to seal outer fuel chamber 40 from
inner fuel chamber 50 disposed below central opening 30. The only
communication between the two fuel chambers is a path through filter
21 87726
element 3, which ensures that all of the fuel will be filtered and no fuel
will circumvent filter element 3.
Special adhesives are required for chemically bonding element
support 6, because the adhesive must be able to withstand being soaked in
the fuel oil (or other medium being filtered), which might tend to dissolve
conventional bonding agents. In a laboratory experiment, a conventional
filter element was chemically bonded to a metal container and a rubber
element support with an adhesive composed of ethyl cyanoacrylate. The
bonded assembly was then soaked in No 2 diesel fuel for 1000 hours. 350
hours of the test included fuel flowing at 90 gallons per hour. Subsequent
to the 1000-hour soaking period, the element support continued to fixedly
and permanently connect the filter element to the metal plate. Other
adhesives that should work satisfactorily include one part epoxies, two
part epoxies, and two part urethanes. One part epoxies usually include a
blend of epoxy resin and a diglycidal ether of bisphenol A ("DGEBPA").
Two part epoxies would include the resin blend of the single component
epoxy, as well as a curing agent, typically a polyalkyl amine or an aliphatic
amine. Using a suitable mixture of the resin blend and the curing agent, as
is known in the art, causes curing to begin at room temperature. The two
part urethane consists of an isocyanate part (typically a mixture of
modified methylene diphenyl isocyanate or urethane prepolymer) and a
resin part (typically a blend of polyols, fillers, catalysts, and other
additives). Again, using a suitable mixture of the isocyanate and resin
parts will start curing at room temperature.
Threaded screw part 1, which may be formed from a suitable plastic
such as nylon, is connected to the bottom of filter container 2 by
conventional glue or similar known means. Threaded part 1 is annular
and has outwardly facing threads 8 for engaging corresponding threads on
a conventional, removable collection bowl (not shown). A central
opening in part 1 (not shown) leads to the collection bowl.
21 ~7726
The fuel filter operates to separate contaminants, such as unwanted
water, from fuel systems in the generally known manner, as follows.
Unfiltered fuel enters the top portion of the container through a number
of inlet holes (not shown) disposed in upper plate 5 around the periphery
5 of central opening 30. These holes may be in fluid communication with
either the inner or outer fuel chamber 50 or 40. Presuming that the inlet
holes communicate with the outer chamber 40, the fuel then flows radially
inward through filter element 3 to the inner fuel chamber 50 in the
middle of filter element 3. The filtered fuel is conducted from the inner
10 fuel chamber though central outlet opening 30 to the engine. The
undesirable contaminants such as water, which are heavier than the fuel,
fall to the bottom of outer chamber 40 or are trapped by the filter medium.
The contaminants pass through clearance space 12 into the opening in the
threaded part 1, which leads to the collection bowl. Alternatively, the filter
15 inlet and outlet may be reversed such that the flow is radially outward
through the filter element. That is, unfiltered fuel may enter filter
container 2 through the central opening 30, pass into the inner fuel
chamber 50, flow radially outwardly through filter element 3 into outer
fuel chamber 40, and be forced out through one or more holes (not shown)
20 in plate 5 which surround central opening 30. In this case, at least one
opening must be provided in the central portion of lower end cap 11 for
the contaminants to flow through, and the outer chamber 40 should be
sealed from the clearance space 12.
Referring now to Fig. 2, the second embodiment of the invention
25 will be described. Like parts have the same reference numerals as in the
previous embodiment, and a description of these parts will not be
repeated. Similarly, the operation of the second embodiment of the
invention is substantially similar to that of the first embodiment.
Upper plate 205 is preferably constructed from drawn steel, and is
30 provided with inwardly facing female threads 215. Upper end cap 210 is
made preferably from molded plastic, and is also provided with inwardly
21 87726
facing female threads 216. As with the first embodiment, the upper end
cap 210, is fixedly attached to the filter medium, and the element support
206 is fixedly attached between the upper plate 205 and the upper end cap
210. However, in this embodiment, female threads 216 of upper end cap
5 210 engage with outwardly facing male threads 217 provided on element
support 206, which forms a mechanical screw lock. Similarly, female
threads 215 of uppcr platc 205 also cllgage t]lC malc tllrcads of clcmcnt
support 206. Thus, instead of providing element support 206 with two
separate mounting surfaces, as in the previous embodiment, the male
10 threads 217 of element support 206 form the mounting surfaces upon
which both upper end cap 210 and plate 205 are secured.
Element support 206 is not only provided with male threads 217, but
also has inwardly facing female threads 221, which engage outwardly
facing threads provided on the filter head (not shown) to replaceably
15 mount the filter on the engine. During the assembly of the filter, a known
chemical, such as LOCTITE may be applied to threads 215, 216, and/or 217
so that filter element 3 may be installed or removed without support 206
being unthreaded from the plate or top end cap. Since relative motion
between support 206, plate 205, and end cap 210 is prevented by the
20 chemical, filter element 3 may be attached onto or detached from upper
end cap 210 without dislodging either plate 205 or top end cap 210, and
filter installation and removal is made significantly easier. ~~~ ~`
Referring now to Fig. 3, the third embodiment of the invention will
be described. Like parts have the same reference numerals as in the
25 previous embodiments, and a description of these parts will not be
repeated. Again, the operation of the third embodiment of the invention
is substantially similar to that of the first embodiment described above.
In this embodiment, a combination of mechanical locking and
chemical bonding features are used to suspend the filter element from the
30 housing. In particular, the element support is fixedly attached to the
housing by a mechanical feature and an adhesive of the invention, while
21 ~7726
13
the upper end cap may be fixed to the element support solely by a
mechan~ical lock. The details of each connection are described below.
With respect to the connection to the filter housing, in a manner
similar to the first embodiment, upper plate 305 is provided with a
5 downwardly depending cylindrical projection 309 which defines a central
opening 330. At a lower portion of cylindrical projection 309, the outer
diameter of the projection increases to form a circumferential lip 315 that
extends radially outward from cylindrical projection 309. Element support
306 is snugly fitted over lip 315 to form an interference fit, i.e., lip 315
10 positively engages into rubber element support 306, to fixedly secure the
element support to the plate mechanically.. Element support 306 may also
be chemically bonded (using an adhesive of the type described above) at its
mounting surface 306-2, shown better in Fig. 5, to upper plate 305 adjacent
to the cylindrical projection 309 of plate 305. The dual mechanical-
15 chemical bonding of element support 306 to plate 305 ensures that theelement support remains securely fixed to the plate.
The filter element is mechanically fixed to element support in the
following manner. As shown best in Fig. 5, element support 306 is
provided with an upper annular shoulder 311 and a lower annular
20 shoulder 313. Shoulders 311 and 313 have a greater thickness than the
remainder of element support 306, thereby forming a recess or mounting
groove 312 therebetween. Mounting groove 312 is adapted to receive
downturned rim 310-1 of upper end cap 310; that is, rim 310-1 is
inlel~erellce or press-fit into mounting groove 312. Optionally, a chemical
25 adhesive of the invention may also be applied to the interface between rim
310-1 and groove 312, to assist in fixedly securing the end cap to the
element support.
A suitable method of making the invention applicable to all three
embodiments is described as follows. First, the upper plate is welded or
30 otherwise fixed to the cover, which forms the top portion of the filter
container. The element support is then attached by threading or adhesive
21 ~7726
14
or both, to the plate/cover sub-assembly. Separately, the threaded screw
part, which is designed to receive a collection bowl, is glued onto the
bottom of the filter container. Meanwhile, the filter element is made by
attaching the end caps to the filter medium. The filter element is then
5 attached in the appropriate manner (depending upon the embodiment,
either chemic~lly, mechanically, or both) to the plate/cover/element
support sub-assembly. Finally, the filter container is placed over and
sealed to the upper plate and cover, and suitable gaskets are installed.
As described above, the invention provides an inexpensive, easy-to-
10 manufacture fuel filter in which the filter element is supported solely bythe element support in a cantilever fashion. No retaining rings or biasing
means are used to support the filter element. The invention also does not
require the use of ribs as either structural supports or as flow diverters.
Thus, the invention is particularly adapted for use as replacement filters
15 for original equipment. The spent filter cartridge may be unthreaded and
removed from the filter head and replaced with a new filter cartridge of
the type described above.
Numerous changes may be made without departing from the scope
or spirit of the invention, which is limited solely by the appended claims.
20 For example, rim 310-1 is depicted in Fig. 3 as being a downturned rim.
However, the invention may instead utilize an upturned rim, as well as
any other configuration. In addition, the precise shape of the element
support is immaterial; the irregularly shaped element support of Fig. 1
may be replaced by an annular element support having a simple
25 rectangular or square cross section, or some other polygonal shape.
