U.S. patent application number 09/737900 was filed with the patent office on 2001-04-26 for fuel filter including slow release additive.
Invention is credited to Martin, Harold R. JR., Stehouwer, David M..
Application Number | 20010000400 09/737900 |
Document ID | / |
Family ID | 23303296 |
Filed Date | 2001-04-26 |
United States Patent
Application |
20010000400 |
Kind Code |
A1 |
Martin, Harold R. JR. ; et
al. |
April 26, 2001 |
Fuel filter including slow release additive
Abstract
This invention relates to a fuel filter for use with internal
combustion engines. The fuel filter includes a fuel additive that
can be released into fuel. The rate of release for the fuel can be
controlled. In one form the fuel additive can be released a
substantially constant rate to maintain a uniform level of fuel
additive in the fuel. Use of the present invention provides a fuel
filter having an extended life span that is longer than fuel
filters typically used with combustion engines.
Inventors: |
Martin, Harold R. JR.;
(Cookeville, TN) ; Stehouwer, David M.;
(Cookeville, TN) |
Correspondence
Address: |
James B. Myers Jr.
Woodard, Emhardt, Naughton, Moriarty and McNett
Bank One Center/Tower
111 Monument Circle, Suite 3700
Indianapolis
IN
46204-5137
US
|
Family ID: |
23303296 |
Appl. No.: |
09/737900 |
Filed: |
December 15, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09737900 |
Dec 15, 2000 |
|
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09333556 |
Jun 16, 1999 |
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Current U.S.
Class: |
210/198.1 |
Current CPC
Class: |
F02M 25/00 20130101;
B01D 37/025 20130101; F02M 37/32 20190101; B01D 27/00 20130101 |
Class at
Publication: |
210/198.1 ;
210 |
International
Class: |
B01D 015/00 |
Claims
erformance and/or fuel efficiency. Under certain conditions fuel is
circulated through the fuel injection where it becomes heated. The
heated fuel can be recirculated through the fuel filter. Since the
fuel has already been through the fuel filter, no additional
additive may be needed. Thus, when the fuel is sufficiently warm,
thermostat 164 can close and prevent the addition of the fuel
additive to the heated fuel. As an additional benefit, tablets 42
can include an anti-gelling agent for diesel fuel. Thermostat 164
can operate to open in response to cool or cold fuel. The
anti-gelling additives can be released on a need-release basis into
the fuel to enhance engine performance in cold weather. Fuel filter
110 can also include, but is not required to include, one or more
baffle plates 150. Similar to the design of fuel filter 10, baffle
plates 150 are positioned in inner chamber 40 adjacent to opening
144 in upper wall 162. Referring now to FIG. 4, another embodiment
of the present invention is illustrated. The basic filter
components of filter 210 are the same as those of filter 10, and
accordingly, the same reference numbers have been used for the
basic components. Alternative and additional components are
referenced with a two hundred prefix designation. Located within
filter 210 is a cap 236 and base plate 34. Cap 236 includes a
double wall structure 267 that includes a semi-permeable membrane
wafer sandwiched therebetween. Cap 236 includes inner surface 252.
Inner surface 252 includes a unitary upper wall 262, which defines
centrally therein an orifice 263. The inner surface 252 includes
molded thereon a small annular lip 264 which serves as a retainer
for circular plate 265. Plate 265 functions as a second wall in
cooperation with upper wall 262 to hold in position therebetween a
substantially cylindrical diffusion or osmotic wafer 248. The
preferred material for diffusion wafer 248 is a microporous
polymer, co-polymer or block copolymer including, but not limited
to: polyethylene glycol or polyvinyl acetate and mixtures thereof.
Plate 265 defines centrally therein an opening 266, which is
aligned with opening orifice 263. This combination permits the
gradual migration of fuel into inner chamber 240 to contact tablets
42. Osmotic wafer 248 is positioned between the fuel additive and
the outlet aperture 30 through which the filtered fuel containing
the fuel additive flows on toward the engine (not shown). Use of
the semi-permeable membrane in the form of membrane 248 permits
only a gradual migration of a portion of fuel in filter chamber 14
into inner chamber 240. This provides a slow release of the fuel
additive composition into the fuel to maintain a substantially
constant level of fuel additive in the fuel system. In FIG. 5 there
is illustrated yet another embodiment of the present invention. The
basic filter components of filter 310 are the same as those of
filter 10, and accordingly, the same reference numbers have been
used for the basic components. Alternative and additional
components are referenced with a three hundred prefix designation.
Filter 310 includes base plate 334 having a lower wall portion 338.
Lower wall portion 338 includes orifice 344 formed therethrough
which provides fluid communication between inner chamber 340 and
filter chamber 314. Lower wall 338 also can include an axially
protruding tapered diffusion tube 348. Diffusion tube 348 defines a
tapered diffusion passageway for orifice 344 that extends
therethrough and establishes a passageway of fluid communication
between the inner chamber 340 and filter chamber 314. Preferably
upper wall 362 of cap 336 includes at least one air vent opening
346. In one alternative form, outlet endplate 332 can include a
substantially circular, hollow vent tube 372 extending obliquely
therefrom and adapted to extend from outlet endplate 332 through
air vent opening 346 to provide fluid communication between region
370 that is proximate to inlet 328 and inner chamber 340. In an
alternative form, the outlet end plates does not include vent tube
372, and air vent opening 346 can vent into the interior region 337
of filter chamber 14. In operation after all the air in inner
chamber 340 has escaped through air vent opening 346, a portion of
the fuel mixture in inner chamber 340 could flow out air vent
opening 346 into interior region 337 and out outlet 30, preferably
at a substantially lower flow rate than fuel flows from annular
space 35 through filter element 16 and out outlet 30. In FIG. 6
there is illustrated an alternative embodiment of a fuel filter 410
for use with the present invention. Fuel filter 410 includes a fuel
additive in a single large tablet or cartridge 442. While it is
possible to include fuel additive cartridge 442 in either of FIG. 1
or FIGS. 3-5, the use of smaller coated tablets is preferred. By
the use of smaller tablets, a larger mass of the fuel additive can
be loaded into the inner chamber without any particular regard to
the size or shape of the chamber. While the foregoing description
provided several embodiments for controlling the release of a fuel
additive composition into fuel, it will be understood that the
inner housing assembly can be formed to include a variety of
structures and openings to allow migration of fuel into the inner
chamber. In preferred embodiments, the inner chamber provides a
quiescent region inside filter chamber where a source of a fuel
additive surrounded by a portion of the fuel flowing through the
fuel filter is protected from the typical fluid forces acting on
the fuel in the filter. The present invention provides a method of
enhancing the operation of an internal combustion engine. In one
form, the enhancement is provided by controlling the release of a
fuel additive into fuel. The controlled released of the additive
maintains a constant, uniform concentration of additive in the
fuel. In preferred embodiments, the additive is released in a
controlled manner to maintain a substantially uniform concentration
of additive in the fuel despite the varying amount of fuel that is
recirculated through the fuel filter. Use of the present invention
decreases the maintenance time and costs, enhances engine
performance and increases fuel efficiency. In another form, the
invention enhances the usable and/or effective lifespan of fuel
filters by providing fuel additives that effectively inhibit the
formation of resinous material such as vanishes and asphaltenes and
help breakup or disperse such material that has been deposited on
fuel handling components. According to the present invention, a
diffusion tube, diffusion orifice, and baffles may be used to slow
the release of the fuel additive into the fuel. The coating on the
fuel additive also limits the rate of additive that is dissolved in
the fuel. These mechanical and chemical arrangements may be used
with a plurality of smaller fuel additive pellets, with a larger
tablet, or with a singular, large cartridge of fuel additive. In an
alternative embodiment of the present invention, a semipermeable
membrane wafer is sandwiched between an upper wall and a retaining
plate to provide a slow release means for the mechanism due to the
composition of the wafer. This mechanical arrangement may be used
with a plurality of smaller tablets or larger tablets or some other
form of fuel additives. Further, a thermostat can be included with
the openings for each embodiment to provide a need-release feature
for the present invention. The thermostat opens in response to fuel
that exhibits a temperature level within a predetermined
temperature range and permits migration of fuel into the inner
chamber. While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is
considered to be illustrative and not restrictive in character, it
is understood that only the preferred embodiments have been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
What is claimed is:
1. A fuel filter for filtering fuel and adapted to release a fuel
additive into said fuel at a controlled rate, said fuel filter
assembly comprising: a housing assembly including an inlet and an
outlet for fuel and defining an filter chamber; a filter element
disposed within said filter chamber and positioned between said
inlet and said outlet for fuel; a source of a fuel additive
disposed within said interior chamber; and a slow release means for
controlling the rate of release of the fuel additive into said
fuel, said slow release means positioned between said source of
fuel additive and said fuel outlet.
2. The fuel filter assembly of claim 1 wherein said source of a
fuel additive includes a plurality of soluble fuel additive
pellets.
3. The fuel filter assembly of claim 2 wherein said soluble fuel
additive pellets are coated with a hydrocarbon insoluble
coating.
4. The fuel filter assembly of claim 1 wherein the slow release
means includes a hydrocarbon insoluble coating.
5. The fuel filter assembly of claim 1 wherein the slow release
means includes a diffusion orifice.
6. The fuel filter assembly of claim 1 wherein the slow release
means includes baffles.
7. The fuel filter assembly of claim 1 wherein the slow release
means includes a semipermeable membrane.
8. The fuel filter assembly of claim 1 wherein said slow release
means includes a thermostatically controlled orifice.
9. A fuel filter for filtering fuel and adapted to release a fuel
additive into said fuel, said fuel filter comprising: an outer
housing assembly defining a filter chamber, an inlet and an outlet
for fuel; a filter element disposed within said filter chamber and
positioned between said inlet and said outlet for fuel; an inner
housing assembly positioned within said filter chamber, said inner
housing assembly defining an inner chamber in fluid communication
with said filter chamber; a source of a fuel additive disposed
within said inner chamber; and a diffusion controlled orifice
positioned between said source of fuel additive and said fuel
outlet.
10. The fuel filter of claim 9 wherein said fuel additive is coated
with a hydrocarbon insoluble coating.
11. The fuel filter of claim 9 further including at least one
baffle plate positioned between said orifice and said source of
fuel additive.
12. The fuel filter of claim 9 wherein said diffusion controlled
orifice includes a thermostat.
13. The fuel filter of claim 9 wherein said diffusion controlled
orifice includes a semipermeable membrane.
14. A fuel filter for filtering fuel and adapted to release a fuel
additive into said fuel, said fuel filter comprising: an outer
housing assembly defining a filter chamber, an inlet and an outlet
for fuel; a filter element disposed within said filter chamber and
positioned between said inlet and said outlet for fuel; an inner
housing assembly positioned within said filter chamber, said inner
housing assembly defining an inner chamber in fluid communication
with said filter chamber; a source of a fuel additive disposed
within said inner chamber; and at least one baffle plate positioned
between said source of fuel additive and said fuel outlet.
15. The fuel filter of claim 14 wherein said fuel additive is
coated with a hydrocarbon insoluble coating.
16. The fuel filter of claim 14 wherein said inner housing assembly
includes a thermostat.
17. A fuel filter for filtering fuel and adapted to release a fuel
additive into said fuel, said fuel filter comprising: an outer
housing assembly defining a filter chamber, an inlet and an outlet
for fuel; a filter element disposed within said filter chamber and
positioned between said inlet and said outlet for fuel; an inner
housing assembly positioned within said filter chamber, said inner
housing assembly defining an inner chamber in fluid communication
with said filter chamber; a source of a fuel additive disposed
within said inner chamber; and a semipermeable membrane positioned
between said source of fuel additive and said fuel outlet.
18. The fuel filter of claim 17 wherein said fuel additive is
coated with a hydrocarbon insoluble coating.
19. The fuel filter of claim 17 wherein said inner housing assembly
includes a thermostat.
20. A method of releasing a fuel additive into fuel, said method
comprising the steps of: providing a fuel filter containing a fuel
additive, said fuel filter positioned between a source of fuel and
an internal combustion engine; contacting a portion of said fuel
additive with a portion of said fuel to provide a fuel composition
comprising fuel additive dissolved in said portion of said fuel;
and allowing said fuel composition to admix with said fuel.
21. The method of claim 20 wherein said fuel additive is coated
with a hydrocarbon insoluble coating.
22. The method of claim 20 wherein said allowing includes
positioning a diffusion control orifice between said fuel
composition and said fuel.
23. The method of claim 20 wherein said allowing includes
positioning at least one baffle plate between said fuel composition
and said fuel.
24. The method of claim 20 wherein said allowing includes allowing
said fuel composition to diffuse into said fuel when said fuel
exhibits a temperature level within a predetermined temperature
range.
Description
FIELD OF THE INVENTION
1. The present invention relates generally to a fuel filter for use
with internal combustion engines, for example, but not limited to
diesel engines in commercial vehicles. More specifically, the
present invention is directed to a fuel filter containing a fuel
additive that can be released into fuel and a method of releasing
the additive into the fuel.
BACKGROUND OF THE INVENTION
2. Fuel filters are necessary components used to protect combustion
engines by filtering out contaminants and thereby preventing damage
to the engine and other downstream components such as valves, fuel
injectors, fuel lines and related components. Fuel can entrain a
wide variety of contaminants from a number of sources. Frequently
fuel oxidizes and forms resinous materials such as asphaltenes
commonly referred to as varnishes. Bacteria can grow in fuel,
particularly fuel that contains moisture. The growing bacteria
forms a "slime" on inner surfaces of fuel tanks, fuel lines and
fuel filters. The slime often sloughs off the surfaces and fuel
transports the free slime through the fuel lines. The fuel filter
filters out the varnishes and bacteria; however, in the process the
varnish and bacteria block the fuel filter element. The blocked
filter exhibits a reduced fuel flow and increases the pressure
differential across the filter element, thereby reducing engine
performance and fuel efficiency. To maintain engine performance and
reliability, the fuel filters must be replaced, often as frequently
as every 2,000 to 4,000 vehicle miles. For many vehicles,
particularly commercial trucks that travel hundreds or even
thousands of miles a month, this significantly increases vehicle
maintenance and operating costs and can reduce reliability.
3. Fortunately, the formation of varnishes and bacteria growth can
be inhibited by adding fuel additives such as antioxidants and
biocides to the fuel. Dispersants can be added to break up and
dissolve some of the existing material clogging the filters and
other fuel related components. To be effective, the additives must
be constantly maintained in the fuel. This is often difficult.
Unlike other fluid systems, such as the coolant and oil systems,
the fuel system does not re-circulate all of the fluid. Therefore,
the additives must be continuously added to the fuel at a
controlled rate.
4. It is difficult to maintain a constant or desired level of an
additive in the fuel. Typically an operator adds a bottled additive
to the vehicle fuel tank with each fuel fill-up. While many bottled
fuel additives are commercially available, often operators do not
consistently add the additive with each fill-up. The additive might
not be readily available or the operator may forget to include the
additive. When the additive is added to the fuel tank, it does not
always form a homogeneous mixture with the fuel. Fuel tanks do not
include reliable methods for mixing fuel. Generally operators rely
upon the turbulence created during a fill-up and by vehicle motion
to mix the additive and fuel. Furthermore, the additive
concentration in the fuel may vary, depending upon the amount of
fuel added-assuming a set amount of additive is added with each
fill-up.
5. The following references provide a background for filters in
general that contain additives.
6. Davis in U.S. Pat. No. 5,372,942 describes a pressurized fuel
filter having an additive embedded in wax; the wax/additive
composition dissolves when contacted with fuel. Additional additive
is only added when a portion of the fuel becomes clogged and the
fuel level in the filter rises to contact and dissolve additional
amounts of the wax/additive composition.
7. Lefebvre in U.S. Pat. No. 5,591,330 discloses an oil filter that
includes a thermoplastic material having oil oxidation and
acidification additives. The hot oil recirculating through the
engine and the filter dissolves that thermoplastic material thereby
releasing the additives into the oil.
8. Hudgens in U.S. Pat. No. 5,662,799 discloses a coolant filter
for recirculating coolant. The coolant filter includes a
supplemental coolant additive (SCA) and a release means to maintain
the concentration of SCA already dissolved in the recirculating
coolant fluid.
9. One of the design challenges addressed by the present invention
is how to control the release of fuel additive into the fuel. The
present invention solves this challenge in several ways, each of
which is believed to be a novel and unobvious solution. The
solution avoids the undesirable side effects, which have already
been described and can be exploited to increase the maintenance
interval, increase the fuel filter life span and enhance engine
performance and fuel efficiency.
SUMMARY OF THE INVENTION
10. In one form the present invention provides a fuel filter for
filtering fuel and adapted to release a fuel additive into the fuel
at a controlled rate. The fuel filter comprises a housing assembly
including an inlet and an outlet for fuel and defining an interior
chamber; a filter element disposed within the interior chamber; a
source of fuel additive disposed within the interior chamber; and a
slow release means for controlling the rate of release of the fuel
additive into the fuel. The slow release means is positioned
between the source of fuel additive and the fuel outlet.
11. In another form the present invention provides a fuel filter
for filtering fuel and adapted to release a fuel additive into the
fuel. The fuel filter comprises an outer housing assembly defining
a filter chamber, an inlet and an outlet for fuel; a filter element
disposed within the filter chamber and positioned between the inlet
and the outlet for fuel; an inner housing assembly positioned
within the filter chamber, the inner housing assembly defining an
inner chamber in fluid communication with the filter chamber; a
source of a fuel additive disposed within the inner chamber; and a
diffusion controlled orifice positioned between the source of fuel
additive and the fuel outlet.
12. In another form the present invention provides a method of
releasing a fuel additive into fuel. The method comprises:
providing a fuel filter containing a fuel additive, the fuel filter
positioned between a source of fuel and an internal combustion
engine; contacting a portion of the fuel additive with a portion of
the fuel to provide a fuel composition comprising fuel additive;
and allowing the fuel composition to admix with the fuel.
13. One object of the present invention is to provide an improved
fuel filter containing a fuel additive.
14. Further objects, features and advantages of the present
invention shall become apparent from the detailed drawing and the
descriptions provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
15. FIG. 1 is a front elevational view in full section of one form
of a fuel filter according to the present invention.
16. FIG. 2 is a top plan view of a baffle plate for use with the
fuel filter of FIG. 1.
17. FIG. 3 is a front elevational view in full section of an
alternative embodiment of a fuel filter comprising a thermostat
according to the present invention.
18. FIG. 4 is a front elevational view in full section of an
alternative embodiment of a fuel filter comprising a semipermeable
membrane according to the present invention.
19. FIG. 5 is a front elevational view in full section of another
embodiment of a fuel filter according to the present invention.
20. FIG. 6 is a front elevational view in full section of yet
another embodiment of a fuel filter comprising a fuel additive
briquette according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
21. For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will, nevertheless, be understood
that no limitation of the scope of the invention is thereby
intended. Any alterations and further modifications in the
described processes, systems, or devices and any further
applications of the principles of the invention as described herein
are contemplated as would normally occur to one skilled in the art
to which the invention relates.
22. Referring to FIG. 1, there is illustrated a fuel filter 10
according to one embodiment of the present invention. The
illustrated embodiment of filter 10 is intended to include basic
components in a construction that is typical of such fuel filters
with the exception of the fuel additive and the slow-release means
associated with the fuel additive. The basic components of filter
10 include housing 12 defining a filter chamber 14, filter element
16 disposed within the filter chamber 14, drain opening 18 having
an externally threaded wall 19, and cap 20 having internal threads
adapted to matingly engage externally threaded wall 19.
23. Housing 12 includes a closed base end 22 and an open outlet end
24, which is crimped to the outer edge periphery of nut plate 26.
The crimped combination creates a filter house assembly 23. Nut
plate 26 provides the inlet openings 28 for fuel to enter filter
10. Internally threaded outlet aperture 30, which is defined by nut
plate 26, provides the flow exit for the filtered fuel.
24. Filter element 16 is supported on one end by outlet end plate
32 and on an opposite end by base plate 34. Filter element 16 is
bonded to end plate 32 to form a fluid tight seal. Fuel enters
filter chamber 14 through inlet 28 and flows to annular space 35.
From annular space 35, fuel flows radially inward through filter
element 16 into an interior region 37, then out through opening 39
of outlet 30. From outlet 30, fuel flows to a combustion engine,
which can include an carburetor system or fuel injection system
(not shown).
25. Base end plate 34 provides a support and a seat for filter
element 16, as well as for the components associated with the
present invention, including the filter additive which is provided
in the form of a plurality of tablets or pellets 42. In the
embodiment illustrated by filter 10 base plate 34 is spaced from
housing 12 by spring 41.
26. The foregoing description of the basic filter components and
construction of fuel filter 10 is provided with regard to FIG. 1
and is applicable to the filter elements depicted in FIGS. 3-6.
Accordingly the same reference numerals will be used for the same
components. The differences between filters illustrated in FIGS. 1
and 3-6 are embodied in the structures that house a plurality of
coated pellet tablets 42.
27. Referring to FIG. 1, fuel filter 10 includes cap 36 and base
plate 34, which matingly join together to form inner chamber 40.
Cap 36 is substantially cylindrical and includes an upper portion
43 sized to have an outside diameter smaller than the inside
diameter of filter chamber 14. Cap 36 includes an annular shelf 45
and an upper wall portion 62. Annular shelf 45 provides support for
filter element 16 and is adapted to form a fluid tight seal with
the lower portion of filter element 16. Upper wall portion 62
includes orifice 44, which provides fluid communication between
inner chamber 40 and inner region 37. The upper wall portion can
also include at least one, preferably two, vent openings 46. Upper
wall 62 includes an axially protruding tapered diffusion tube 48.
Diffusion tube 48 defines a tapered diffusion passageway for
orifice 44, which extends therethrough and establishes a passageway
of fluid communication between the inner chamber 40 and inner
region 37.
28. Referring additionally to FIG. 2, there is illustrated a
typical baffle plate 50 for use with the present invention. Cap 36
can include, but is not required to include, at least one,
preferably a plurality, of baffle plates 50. Each baffle plate 50
includes a plurality of openings 51 formed therethrough. Baffle
plate 50 is spaced from diffusion tube 48. In preferred
embodiments, cap 36 includes three baffle plates 50 spaced from
each other; each baffle plate individually bonded about its
peripheral edge to inner surface 52 of cap 36. It will be
appreciated that in alternative forms cap 36, which includes at
least one baffle plate 50, need not include a diffusion control
orifice or the diffusion tube 48. When thus provided, cap 36 has an
opening providing fluid communication with filter chamber 12 and
includes a sufficient number of baffle plates 50 to slow the flow
of fuel into inner chamber 40 and/or to control the rate of release
of the fuel additive. Further, a plurality of baffle plates 50 can
be provided to reduce turbulence in inner chamber 44. Preferably,
each baffle plate 50 is spaced from an adjacent baffle plate to
misalign the plurality of openings 51 in the adjacent baffle
plates.
29. As is illustrated in FIG. 1, cap 36 seats on base plate 34 and
forms an inner housing 43 assembly that defines inner chamber 40.
The only openings into inner chamber 40 are the diffusion orifice
44 and vent openings 46. Inner chamber 40 is substantially filled
with a fuel additive composition, which is illustrated in a form of
a tablet 42. It is understood that the fuel additive composition
can be provided in a variety of shapes and sizes, including cubic,
cylindrical, and spherical. Typically, tablets 42 are provided in a
cubic shape to fill the inner chamber 40.
30. Fuel from filter chamber 12 in filter 10 migrates through the
diffusion orifice 44 into an inner chamber 40. Fuel in inner
chamber 40 contacts the outer coating 47 of fuel additive tablet
42. Fuel then diffuses through the coating 47 to contact the fuel
additive composition, which dissolves in the fuel to provide a fuel
composition comprising the dissolved additive. The fuel composition
diffuses back through coating 47 into inner chamber 40. The fuel
composition mixes with fuel in inner chamber 40.
31. The fuel system is unlike the coolant and oil systems used with
internal combustion engines because in some duty cycles the fuel
system does not recirculate a significant portion of fluid.
Therefore, under these conditions, the majority of fuel entering
into filter chamber 14 has not been recirculated through filter 10
and for all practical purposes does not include any dissolved
additive. While not intending to be bound by any theory, it is
believed that the concentration of dissolved additive in the fuel
composition in inner chamber 40 is vastly greater than the
concentration of dissolved additive in the fuel in filter chamber
14 outside inner chamber 40. This concentration difference is
significantly greater than would be expected in a recirculating
fluid system. This concentration difference creates a stronger
driving force for the fuel composition to migrate from inner
chamber 40 into filter chamber 40. In preferred embodiments, baffle
plate 50 and/or diffusion orifice 44 are provided to inhibit or
reduce the flow of fuel into and out from inner chamber 40. This
increases the useful lifespan of fuel filter 10 and controls the
rate of release of the fuel additive composition into the fuel.
32. Inner chamber 40 provides a substantially quiescent region
inside filter chamber 12 that does not experience the currents
created by fuel flowing through filter 10. As the concentration of
dissolved fuel additive in inner chamber 40 increases relative to
concentration of the fuel additive in filter chamber 12, the fuel
composition migrates or diffuses from inner chamber 40 into filter
chamber 12 in an effort to achieve equilibrium. The fuel
composition comprising the dissolved additive and the fuel diffuses
through diffusion tube 48 and diffusion orifice 44 that defines a
restricted opening for the migration of the higher concentration
solution out of the inner chamber 40 and mixes with fuel in filter
chamber 14.
33. The fuel additives for use in this invention can be of liquid
or solid form. Two or more fuel additives can be combined to form a
fuel additive composition. The fuel additive(s) can be compounded
with a suitable polymer either for providing a solid or semisolid
material such as tablet 42 or form for providing a matrix to
control the rate of release of the additive into the fuel. The fuel
additive can further include a wide variety of binders, compounding
agents and mold release agents. When the additive is provided in
liquid form, it is preferable, but not required, to combine the
liquid fuel additive with a suitable agent to form a solid or
semisolid material. As used herein, the term fuel additive includes
any commercially known and/or commonly used fuel additive that
imparts beneficial properties to the fuel and/or the engine and
related fuel-handling components. Common classes of fuel additives
include: antioxidants, antiwear agents, cetane improvers, corrosion
inhibitors, demulsifiers, detergents, dispersants, flow improvers,
lubricity agents, and metal deactivators.
34. Tablets 42 of fuel additive include an outer hydrocarbon
insoluble coating 47, which encases the fuel additive composition
tablet 42. The hydrocarbon insoluble coating is selected to be
substantially insoluble in hydrocarbon fuel mixtures, yet be
permeable to the fuel to allow the fuel to penetrate the coating
and contact the fuel additive. A portion of the fuel additive
dissolves in the fuel to provide a fuel composition that includes
the dissolved fuel additive. The coating may be a hard coating or a
soft pliable coating. In general, any coating material can be used
with this invention, provided the coating allows fuel access to the
fuel additive composition and does not harm downstream fuel
systems, fuel injectors, valves and related engine components.
35. Typical and preferred coating materials are commercial
available polymers co-polymers and block copolymers including, but
not limited to: polyethylene glycol or polyvinyl acetate and
mixtures thereof. Preferably the coating is selected to provide an
effective rate of release of the additive into the fuel. By
effective rate of release, it will be understood that the additive
is released at a concentration sufficient to provide beneficial
properties to the fuel and related fuel-handling components.
36. In other embodiments, the fuel additive can be embedded within
a solid matrix. The matrix can be either hydrocarbon soluble or
hydrocarbon insoluble. If the matrix material is hydrocarbon
insoluble, the fuel must be able to penetrate the matrix and
contact the fuel additive. It is particularly advantageous to embed
a liquid fuel additive in a solid matrix. This provides one means
of controlling the rate the additive is released into fuel.
37. One alternative design of FIG. 1 includes replacing the
plurality of coated tablets 42 with a fewer number of much larger
pellets or tablets. By reducing the total surface area of the fuel
additive for a specific mass of fuel additive composition, the
additive composition dissolves at a slower rate.
38. Referring now to FIG. 3, an alternative embodiment of the
present invention is illustrated. As has been previously mentioned,
the basic filter components of filter 110 are the same as those of
filter 10, and accordingly, the same reference numbers have been
used for the basic components. Alternative and additional
components are referenced with a one hundred prefix designation.
Located within filter I 10 is cap 136 and base plate 34. Cap 136
includes opening 144 formed therethrough. Opening 144 can be
provided in the form of a diffusion orifice that is defined by a
diffusion tube 148. Thermostat 164 is provided in opening 144.
Thermostat 164 is adapted to control the flow of fuel into inner
chamber 40 and can be selected from a wide variety of commercially
available thermostats. For example, a wax type thermostat can be
adapted for use in the present invention. In preferred operation,
the thermostat opens in response to a temperature level of fuel in
filter 110. When opened, the thermostat allows passage of fuel into
inner chamber 40. The thermostat 164 can be adapted to open in
response to either fuel that is sufficiently warm or fuel that is
sufficiently cool.
39. In one preferred embodiment, thermostat 164 opens in response
to fuel that is sufficiently warm. Fuel additives providing
additional benefits to warm fuel can be released on an as-needed
release basis. For example, antioxidants and dispersants can be
added to the warm fuel to inhibit the deposition of resinous
material on filter element 16. Dispersions can be provided to
suspend or dissolve the resinous material, which are eventually
burned in an engine (not shown). In alternative embodiments, the
thermostat 164 opens when fuel in filter 110 is sufficiently cool.
Cool fuel can be indicative of a recently filled tank or of fuel
that has not been recirculated through the fuel filter. In either
case, the cool fuel may require additional additives to enhance
engine performance and/or fuel efficiency. Under certain conditions
fuel is circulated through the fuel injection where it becomes
heated. The heated fuel can be recirculated through the fuel
filter. Since the fuel has already been through the fuel filter, no
additional additive may be needed. Thus, when the fuel is
sufficiently warm, thermostat 164 can close and prevent the
addition of the fuel additive to the heated fuel.
40. As an additional benefit, tablets 42 can include an
anti-gelling agent for diesel fuel. Thermostat 164 can operate to
open in response to cool or cold fuel. The anti-gelling additives
can be released on a need-release basis into the fuel to enhance
engine performance in cold weather.
41. Fuel filter 110 can also include, but is not required to
include, one or more baffle plates 150. Similar to the design of
fuel filter 10, baffle plates 150 are positioned in inner chamber
40 adjacent to opening 144 in upper wall 162.
42. Referring now to FIG. 4, another embodiment of the present
invention is illustrated. The basic filter components of filter 210
are the same as those of filter 10, and accordingly, the same
reference numbers have been used for the basic components.
Alternative and additional components are referenced with a two
hundred prefix designation. Located within filter 210 is a cap 236
and base plate 34. Cap 236 includes a double wall structure 267
that includes a semi-permeable membrane wafer sandwiched
therebetween.
43. Cap 236 includes inner surface 252. Inner surface 252 includes
a unitary upper wall 262, which defines centrally therein an
orifice 263. The inner surface 252 includes molded thereon a small
annular lip 264 which serves as a retainer for circular plate 265.
Plate 265 functions as a second wall in cooperation with upper wall
262 to hold in position therebetween a substantially cylindrical
diffusion or osmotic wafer 248. The preferred material for
diffusion wafer 248 is a microporous polymer, co-polymer or block
copolymer including, but not limited to: polyethylene glycol or
polyvinyl acetate and mixtures thereof. Plate 265 defines centrally
therein an opening 266, which is aligned with opening orifice 263.
This combination permits the gradual migration of fuel into inner
chamber 240 to contact tablets 42. Osmotic wafer 248 is positioned
between the fuel additive and the outlet aperture 30 through which
the filtered fuel containing the fuel additive flows on toward the
engine (not shown). Use of the semi-permeable membrane in the form
of membrane 248 permits only a gradual migration of a portion of
fuel in filter chamber 14 into inner chamber 240. This provides a
slow release of the fuel additive composition into the fuel to
maintain a substantially constant level of fuel additive in the
fuel system.
44. In FIG. 5 there is illustrated yet another embodiment of the
present invention. The basic filter components of filter 310 are
the same as those of filter 10, and accordingly, the same reference
numbers have been used for the basic components. Alternative and
additional components are referenced with a three hundred prefix
designation. Filter 310 includes base plate 334 having a lower wall
portion 338. Lower wall portion 338 includes orifice 344 formed
therethrough which provides fluid communication between inner
chamber 340 and filter chamber 314. Lower wall 338 also can include
an axially protruding tapered diffusion tube 348. Diffusion tube
348 defines a tapered diffusion passageway for orifice 344 that
extends therethrough and establishes a passageway of fluid
communication between the inner chamber 340 and filter chamber
314.
45. Preferably upper wall 362 of cap 336 includes at least one air
vent opening 346. In one alternative form, outlet endplate 332 can
include a substantially circular, hollow vent tube 372 extending
obliquely therefrom and adapted to extend from outlet endplate 332
through air vent opening 346 to provide fluid communication between
region 370 that is proximate to inlet 328 and inner chamber 340. In
an alternative form, the outlet end plates does not include vent
tube 372, and air vent opening 346 can vent into the interior
region 337 of filter chamber 14. In operation after all the air in
inner chamber 340 has escaped through air vent opening 346, a
portion of the fuel mixture in inner chamber 340 could flow out air
vent opening 346 into interior region 337 and out outlet 30,
preferably at a substantially lower flow rate than fuel flows from
annular space 35 through filter element 16 and out outlet 30.
46. In FIG. 6 there is illustrated an alternative embodiment of a
fuel filter 410 for use with the present invention. Fuel filter 410
includes a fuel additive in a single large tablet or cartridge 442.
While it is possible to include fuel additive cartridge 442 in
either of FIG. 1 or FIGS. 3-5, the use of smaller coated tablets is
preferred. By the use of smaller tablets, a larger mass of the fuel
additive can be loaded into the inner chamber without any
particular regard to the size or shape of the chamber.
47. While the foregoing description provided several embodiments
for controlling the release of a fuel additive composition into
fuel, it will be understood that the inner housing assembly can be
formed to include a variety of structures and openings to allow
migration of fuel into the inner chamber. In preferred embodiments,
the inner chamber provides a quiescent region inside filter chamber
where a source of a fuel additive surrounded by a portion of the
fuel flowing through the fuel filter is protected from the typical
fluid forces acting on the fuel in the filter.
48. The present invention provides a method of enhancing the
operation of an internal combustion engine. In one form, the
enhancement is provided by controlling the release of a fuel
additive into fuel. The controlled released of the additive
maintains a constant, uniform concentration of additive in the
fuel. In preferred embodiments, the additive is released in a
controlled manner to maintain a substantially uniform concentration
of additive in the fuel despite the varying amount of fuel that is
recirculated through the fuel filter. Use of the present invention
decreases the maintenance time and costs, enhances engine
performance and increases fuel efficiency. In another form, the
invention enhances the usable and/or effective lifespan of fuel
filters by providing fuel additives that effectively inhibit the
formation of resinous material such as vanishes and asphaltenes and
help breakup or disperse such material that has been deposited on
fuel handling components.
49. According to the present invention, a diffusion tube, diffusion
orifice, and baffles may be used to slow the release of the fuel
additive into the fuel. The coating on the fuel additive also
limits the rate of additive that is dissolved in the fuel. These
mechanical and chemical arrangements may be used with a plurality
of smaller fuel additive pellets, with a larger tablet, or with a
singular, large cartridge of fuel additive. In an alternative
embodiment of the present invention, a semipermeable membrane wafer
is sandwiched between an upper wall and a retaining plate to
provide a slow release means for the mechanism due to the
composition of the wafer. This mechanical arrangement may be used
with a plurality of smaller tablets or larger tablets or some other
form of fuel additives. Further, a thermostat can be included with
the openings for each embodiment to provide a need-release feature
for the present invention. The thermostat opens in response to fuel
that exhibits a temperature level within a predetermined
temperature range and permits migration of fuel into the inner
chamber.
50. While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is
considered to be illustrative and not restrictive in character, it
is understood that only the preferred embodiments have been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
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