U.S. patent application number 11/346911 was filed with the patent office on 2007-01-25 for fuel tank venting arrangement.
Invention is credited to Ronald J. Donahue, J. David Kirk.
Application Number | 20070017918 11/346911 |
Document ID | / |
Family ID | 37056928 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070017918 |
Kind Code |
A1 |
Kirk; J. David ; et
al. |
January 25, 2007 |
Fuel tank venting arrangement
Abstract
A fuel tank for small internal combustion engines, the fuel tank
formed of a pair of lower and upper housing members which are
molded from a plastic material and are sealed to one another via
heat welding, for example, to define the interior volume of the
fuel tank. The lower housing member includes an integral vent tube
which extends substantially upwardly within the interior of the
fuel tank and includes an open end. The upper housing member
includes an integral baffle wall projecting downwardly therefrom
which defines a baffle chamber in which the upper end of the vent
tube is received. The lower housing member additionally includes an
integral fitting to which a vent conduit is attached, the fitting
in fluid communication with the vent tube. In use, fuel vapors are
vented from the fuel tank by passing into the baffle chamber and
thence into the open end of the vent tube and through the fitting
and vent conduit to a carbon canister or other containment
device.
Inventors: |
Kirk; J. David; (Fond Du
Lac, WI) ; Donahue; Ronald J.; (Fond Du Lac,
WI) |
Correspondence
Address: |
BAKER & DANIELS LLP;111 E. WAYNE STREET
SUITE 800
FORT WAYNE
IN
46802
US
|
Family ID: |
37056928 |
Appl. No.: |
11/346911 |
Filed: |
February 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60700779 |
Jul 20, 2005 |
|
|
|
60758505 |
Jan 12, 2006 |
|
|
|
Current U.S.
Class: |
220/563 |
Current CPC
Class: |
B60K 2015/03111
20130101; B60K 2015/03236 20130101; B60K 2015/03523 20130101; B60K
2015/0344 20130101; B60Y 2200/225 20130101; B60K 15/035 20130101;
A01D 34/82 20130101; B60K 15/077 20130101; B60K 2015/03547
20130101; F02M 25/0872 20130101 |
Class at
Publication: |
220/563 |
International
Class: |
B65D 88/12 20060101
B65D088/12 |
Claims
1. A fuel tank, comprising: at least two housing members joined to
one another to define an interior volume therebeween; an elongated
vent tube monolithically formed with one of said housing members
and extending therefrom within said interior volume.
2. The fuel tank of claim 1, wherein at least a portion of said
vent tube is oriented substantially vertically.
3. The fuel tank of claim 1, further comprising a fuel blocking
element associated with said vent tube, said fuel blocking element
substantially blocking the passage of liquid fuel therethrough into
said vent tube and allowing the passage therethrough of gaseous
fuel vapors when pressure in said fuel tank rises above atmospheric
pressure.
4. The fuel tank of claim 3, wherein said fuel blocking element
extends within said vent tube along a substantial portion of the
length of said vent tube.
5. The fuel tank of claim 1, wherein another of said housing
members includes a baffle wall disposed within said interior
volume, said baffle wall defining a baffle space, an end of said
vent tube disposed within said baffle space.
6. The fuel tank of claim 5, further comprising a fuel blocking
element associated with said vent tube, said fuel blocking element
at least one of: disposed within an open upper end of said vent
tube; disposed within said baffle space; and disposed around said
vent tube.
7. The fuel tank of claim 1, wherein said baffle wall extends along
a substantial portion of a length of said vent tube.
8. The fuel tank of claim 1, wherein said one housing member
includes a wall recessed into said interior volume to define a
recessed space exteriorly of said interior volume, said vent tube
extending from said wall into said interior volume.
9. The fuel tank of claim 8, wherein said one housing member
further includes a fitting monolithically formed therewith, said
fitting disposed within said recessed space and in fluid
communication with said vent tube.
10. The fuel tank of claim 1, wherein said fuel tank further
comprises a filler neck, said filler neck having a lower end
disposed within said interior volume and defining a maximum fuel
level within said fuel tank.
11. The fuel tank of claim 10, wherein said fuel tank further
comprises a vapor space defined therewithin above said lower end of
said filler neck.
12. The fuel tank of claim 1, wherein said fuel tank further
comprises a fuel tank cap, said fuel tank cap including a one-way
valve therein allowing passage of atmospheric air therethrough into
said fuel tank and preventing the passage of air therethrough from
said fuel tank to the atmosphere.
13. A fuel tank, comprising: at least two housing members joined to
one another to define an interior volume therebeween; an elongated
vent tube connected to one of said housing members and extending
therefrom within said interior volume; and a fuel blocking element
disposed within said vent tube and extending within said vent tube
along a substantial portion of a length of said vent tube, wherein
said fuel blocking element substantially blocks the passage of
liquid fuel therethrough into said vent tube and allows the passage
therethrough of gaseous fuel vapors when pressure in said fuel tank
rises above atmospheric pressure.
14. The fuel tank of claim 13, wherein said vent tube is
monolithically formed with one of said housing members.
15. The fuel tank of claim 13, wherein another of said housing
members includes a baffle wall disposed within said interior
volume, said baffle wall defining a baffle space, an end of said
vent tube disposed within said baffle space.
16. The fuel tank of claim 15, wherein said baffle wall extends
along a substantial portion of said vent tube.
17. The fuel tank of claim 13, wherein said one housing member
includes a wall recessed into said interior volume to define a
recessed space exteriorly of said interior volume, said vent tube
extending from said wall into said interior volume.
18. The fuel tank of claim 17, wherein said one housing member
further includes a fitting monolithically formed therewith, said
fitting disposed within said recessed space and in fluid
communication with said vent tube.
19. The fuel tank of claim 13, wherein said fuel tank further
comprises a fuel tank cap, said fuel tank cap including a one-way
valve therein allowing passage of atmospheric air therethrough into
said fuel tank and preventing the passage of air therethrough from
said fuel tank to the atmosphere.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit under Title 35,
U.S.C. .sctn. 119(e) of U.S. Provisional Patent Application Ser.
No. 60/700,779 entitled FUEL TANK VENTING ARRANGEMENT, filed on
Jul. 20, 2005, and U.S. Provisional Patent Application Ser. No.
60/______ entitled FUEL TANK VENTING ARRANGEMENT, filed on Jan. 12,
2006 (Attorney Docket Ref.: TEL0770-01).
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to small internal combustion
engines of the type which are used with lawnmowers, lawn and garden
tractors, other utility implements such as snow throwers and
generators, and in sport vehicles, for example. In particular, the
present invention relates to an arrangement for venting the fuel
tanks of such engines.
[0004] 2. Description of the Related Art
[0005] Small internal combustion engines include fuel tanks for
storing liquid fuel which is mixed with air in the carburetor of
the engine to provide a fuel/air mixture for combustion within the
engine. Typically, the fuel tank is made from metal or from an
injection-molded plastic, for example, and is mounted toward the
upper portion of the engine such that the liquid fuel within the
tank may flow by gravity into the fuel bowl of the carburetor.
Typically, the carburetor includes a float-type valve assembly for
metering a supply of liquid fuel from the fuel tank into the
carburetor float bowl.
[0006] It is known that some of the liquid fuel within the fuel
tank may vaporize responsive to heat from the running engine or
from warm ambient conditions, for example, to form fuel vapors in
the space above the liquid fuel. These fuel vapors must be vented
from the fuel tank to avoid over-pressurization of the fuel tank.
In many known fuel tanks, such vapors are vented directly into the
atmosphere through a space or pathway provided between the
cooperating threads of the fuel tank cap and the filler neck. Other
known fuel tanks employ various types of valve structures for
venting fuel vapors to a containment device such as a carbon
canister, for example, wherein the fuel vapors are consumed within
the engine when the engine is started.
[0007] One known fuel tank is made from an injection-molded
plastic, and includes a metal vent tube disposed within the
interior of the fuel tank. The lower end of the metal tube is
bonded to a metal fitting which is threaded into internal threads
of a boss which is molded within the lower wall of the fuel tank.
The upper end of the metal vent tube is disposed within a baffle
wall formed in the top wall of the fuel tank to prevent liquid fuel
from being splashed into the upper end of the vent tube, and a
conduit is attached to the metal fitting at the lower end of the
vent tube. In use, vapors within the fuel tank may pass into the
space within the baffle wall, into the upper end of the vent tube,
and thence downwardly through the vent tube, the fitting, and the
conduit to be vented externally of the fuel tank.
[0008] A problem with the foregoing arrangement is that the
threaded connection between the metal vent tube fitting and the
plastic threads of the fuel tank boss may not be sufficiently
durable, and could be prone to eventual leakage due to engine
vibrations or other external forces, for example. Also, the
foregoing arrangement requires several parts in addition to the
fuel tank itself, such as the metal vent tube and the metal
fitting, which add manufacturing steps and additional cost to
production of the fuel tank.
[0009] What is needed is a fuel tank having a venting arrangement
which is an improvement over the foregoing.
SUMMARY OF THE INVENTION
[0010] The present invention provides a fuel tank for small
internal combustion engines, the fuel tank formed of a pair of
lower and upper housing members which are molded from a plastic
material and are sealed to one another via heat welding, for
example, to define the interior volume of the fuel tank. The lower
housing member includes an integral vent tube which extends
substantially upwardly within the interior of the fuel tank and
includes an open end. The upper housing member includes an integral
baffle wall projecting downwardly therefrom which defines a baffle
chamber in which the upper end of the vent tube is received. The
lower housing member additionally includes an integral fitting to
which a vent conduit is attached, the fitting in fluid
communication with the vent tube. In use, fuel vapors are vented
from the fuel tank by passing into the baffle chamber and thence
into the open end of the vent tube and through the fitting and vent
conduit to a carbon canister or other containment device.
[0011] Additionally, the fitting of the lower housing member may be
provided within a recessed area of the lower housing member such
that the connection of the vent conduit to the fitting is hidden
from view and protected against external contacts which could
potentially disconnect the hose from the fitting. Also, the lower
housing member may include an additional recessed groove for
receipt of the vent conduit. The filler neck of the fuel tank is
integrally formed with the upper housing member and extends
downwardly within the interior volume of the fuel tank such that,
when fuel is filled into the fuel tank, a vapor space is defined in
the upper portion of the fuel tank in which fuel vapors may collect
and thence be vented from the fuel tank.
[0012] Advantageously, the vent tube and fitting are each
integrally formed with the lower housing member, and the baffle
wall and filler neck are integrally formed with the upper housing
member, thereby reducing the cost of production of the fuel tank
and eliminating the need for a plurality of separate components
associated with the venting arrangement, such as separate vent
tubes and fittings.
[0013] In one form thereof, the present invention provides a fuel
tank, including at least two housing members joined to one another
to define an interior volume therebeween; and an elongated vent
tube monolithically formed with one of the housing members and
extending therefrom within the interior volume.
[0014] In another form thereof, the present invention provides a
fuel tank, including at least two housing members joined to one
another to define an interior volume therebeween; an elongated vent
tube connected to one of the housing members and extending
therefrom within the interior volume; and a fuel blocking element
disposed within the vent tube and extending within the vent tube
along a substantial portion of a length of the vent tube, wherein
the fuel blocking element substantially blocks the passage of
liquid fuel therethrough into the vent tube and allows the passage
therethrough of gaseous fuel vapors when pressure in the fuel tank
rises above atmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention itself will be better understood by
reference to the following description of embodiments of the
invention taken in conjunction with the accompanying drawings,
wherein:
[0016] FIG. 1 is a perspective view of an exemplary implement,
shown herein as a lawnmower, which includes a small internal
combustion engine with which the fuel tank of the present invention
may be used;
[0017] FIG. 2 is a perspective top view of the fuel tank;
[0018] FIG. 3 is a perspective bottom view of the fuel tank;
[0019] FIG. 4 is a sectional view through the fuel tank, taken
along line 4-4 of FIG. 2;
[0020] FIG. 5 is a fragmentary view of a portion of the fuel tank
of FIG. 4, showing agitation of the fuel within the fuel tank;
[0021] FIG. 6 is a fragmentary view of a portion of the fuel tank
of FIG. 4, showing a one-way valve integrated into the fuel tank
cap;
[0022] FIG. 7 is a sectional view of a fuel tank in accordance with
another embodiment, showing the fuel tank in an upright
orientation; and
[0023] FIG. 8 is a sectional view of a fuel tank in accordance with
another embodiment, showing the fuel tank in an inverted
orientation.
[0024] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate preferred embodiments of the invention, and such
exemplifications are not to be construed as limiting the scope of
the invention any manner.
DETAILED DESCRIPTION
[0025] Referring to FIG. 1, an exemplary implement having an engine
with which the fuel tank of the present invention may be used is
shown as lawnmower 10. Lawnmower 10 generally includes deck 12
having wheels 14, and handle 16 extending upwardly from deck 12 to
allow lawnmower 10 to be moved about by an operator. Additionally,
lawnmower 10 includes a small one or two cylinder internal
combustion engine 18, which may be of the side valve or L-head
type, the overhead valve ("OHV") type, or the overhead cam ("OHC")
type, such as engines currently manufactured by Tecumseh Products
Company of Grafton and New Holstein, Wis. Generally, engine 18
includes a carburetor 20 for providing a fuel/air mixture for
combustion within engine 18 to drive the piston/connecting
rod/crankshaft assembly (not shown) of engine 18 to rotate a
cutting blade (not shown) beneath deck 12 of lawnmower 10.
[0026] Engine 18 additionally includes fuel tank 22 mounted thereto
for storing a volume of liquid fuel which is supplied to fuel bowl
24 of carburetor 20 in the manner described below. Typically,
carburetor 20 includes a float-type valve (not shown) within fuel
bowl 24 to meter a supply of liquid fuel from fuel tank 22 into
fuel bowl 24. Carburetor 20 may be of the type disclosed in U.S.
Pat. Nos. 6,152,431, 6,499,726, and 6,513,794, each assigned to the
assignee of the present invention, the disclosures of which are
incorporated herein by reference.
[0027] Referring to FIGS. 2-4, fuel tank 22 generally includes
lower housing member 26 and upper housing member 28. Lower housing
member 26 and upper housing member 28 are each single, monolithic
components including the various features described below, and
which may each be formed from an injection-molded plastic, such as
polyethylene, for example. Lower housing member 26 and upper
housing member 28 include mutually facing outer rim surfaces 30 and
32, respectively, which are in abutment with one another and are
secured to one another via heat welding, for example, to define an
interior volume 34 within fuel tank 22. In addition, outer rim
surfaces 30 and 32 may include suitable overlapping and/or
interlocking features. Although fuel tank 22 is shown and described
herein as including lower and upper housing members 26 and 28
joined to one another along a substantially horizontal interface,
fuel tank 22 could also be formed from left and right housing
members joined along a substantially vertical interface, for
example, or may be formed from any two or more housing members
which may be joined along an interface which is disposed at an
angle with respect to horizontal and vertical.
[0028] Upper housing member 28 generally includes top wall 36 with
side wall 38 depending therefrom. Upper housing member 28 also
includes filler neck 38 integrally/monolithically formed therewith
which is cylindrically-shaped and, as shown in FIG. 4, includes an
upper, threaded portion 40 disposed externally of fuel tank 22
within a recess 42 defined within top wall 36. Recess 42 includes
splash guard wall 44 to direct any spilled fuel in a desired
direction away from fuel tank 22. Filler neck 38 also includes a
lower, baffle portion 46 extending downwardly into interior volume
34 of fuel tank 22.
[0029] Fuel tank cap 50 includes inner threads 52 for threading
attachment to outer threads 54 of filler neck 50 to close fuel tank
22, wherein inner threads 52 of fuel tank cap 50 and outer threads
54 of filler neck 38 form a seal therebetween such that fuel vapors
within fuel tank 22 cannot escape through the foregoing threads.
Additionally, fuel tank cap 50 may optionally include an O-ring or
other seal member 55 for providing a seal between fuel tank cap 50
and filler neck 40. Thus, fuel tank cap 50 is of the "non-venting"
type in which fuel vapors cannot vent from internally of fuel tank
22 through fuel tank cap 50. In one embodiment, however, fuel tank
cap may include a one-way valve as described below with reference
to FIG. 6.
[0030] Upper housing member 28 additionally includes a vapor space
56 defined within interior volume 34 of fuel tank 22 above baffle
portion 46 of filler neck 40. In use, when a user fills liquid fuel
into fuel tank 22, air is trapped within vapor space 56 when the
level of fuel rises to the lower end, or just above the lower end,
of baffle portion 46 of filler neck 40. The air trapped within
vapor space 56 prevents additional fuel from entering vapor space
56, and thereafter, any additional liquid fuel filled into fuel
tank 22 rapidly fills up filler neck 40 to indicate to the user
that fuel tank 22 is full. In this manner, the level of baffle
portion 46 of filler neck 40 defines the maximum fill level for
fuel within fuel tank 22. Vapor space 56 also provides a volume of
air within fuel tank 22 in which vapors from the liquid fuel in
fuel tank 22 may collect.
[0031] Upper housing member 28 further includes baffle wall 58
extending therefrom, which is integrally/monolithically formed with
upper housing member 28. Baffle wall 58 may have a circular,
square, or other polygonal shape in cross-section, for example, and
generally protrudes downwardly from upper housing member 28 to a
form baffle recess or space 60 therein, the function of which is
described further below.
[0032] Lower housing member 26 generally includes a lower bottom
wall 62, an upper bottom wall 64, an intermediate wall connecting
lower and upper bottom walls 62 and 64, and side wall 68. Lower
bottom wall 62 and side wall 68 define a lowermost portion within
interior volume 34 of fuel tank 22. Fuel outlet fitting 70 is
integrally/monolithically formed within lower bottom wall 62 in
fluid communication with the lowermost portion of interior volume
34 of fuel tank 22, and a fuel conduit 72 (FIG. 3) may be attached
to fuel outlet fitting 70. In use, liquid fuel within fuel tank 22
drains by gravity through fuel outlet fitting 70 and passes through
fuel conduit 72 to fuel bowl 24 of carburetor 20. Fuel tank 22 may
also include a water trap (not shown) and/or a water-repellant
screen (not shown) mounted over the interior side of fuel outlet
fitting 70 of the type disclosed in U.S. Pat. No. 6,953,527,
assigned to the assignee of the present invention, the disclosure
of which is incorporated by reference. A plurality of brackets 73
may be formed integrally with, or otherwise attached to, lower
housing member 26 for mounting fuel tank 22 to engine 20.
[0033] Lower housing member 26 additionally includes a recessed
wall 74 projecting inwardly therein to define a concave or recess
space 76 in lower housing member 26, as well as vent tube 78 and
vent fitting 80 which are each integrally/monolithically formed
with lower housing member 26. Vent tube 78 is generally elongate in
shape, and extends generally upwardly from lower housing member 26
into the interior volume 34 of fuel tank 22 and upwardly into vapor
space 56. Upon attachment of lower housing member 26 to upper
housing member 28 in the manner described above, upper end 82 of
vent tube 78 is positioned generally within the baffle space 60
which is defined by baffle member 58 of upper housing member 28.
Typically, upper end 82 of vent tube 78 is disposed above the lower
end of baffle member 58, as shown in FIG. 5, such that baffle
member 58 prevents fuel from splashing into upper end 82 of vent
tube 78 when the fuel in fuel tank 22 is agitated, as discussed
below.
[0034] Vent fitting 80 projects into recess space 76 and is in
fluid communication with vent tube 78, and also includes at least
one, and preferably a plurality of, barbs 84 therealong for
press-fit attachment thereto of vent conduit 86. In this manner,
vent fitting 80 is advantageously located within recess space 76 of
lower housing member 26, such that the connection between vent
conduit 86 and vent fitting 80 is hidden from view and is protected
against external contacts or jostling which could potentially
disengage vent conduit 84 from vent fitting 80. Optionally, lower
housing member 26 may also include a recessed groove 88 (FIG. 3) in
which vent conduit 86 may be fitted to protect vent conduit 86 from
external contacts, for example.
[0035] Advantageously, vent tube 78 and vent fitting 80 are
integrally formed with lower housing member 26, thereby obviating
the need for additional parts such as a separate vent tube and vent
fitting, and also eliminating the need for a connection between a
separate vent tube and/or vent fitting with the fuel tank 22 which
might be prone to leakage.
[0036] Referring generally to FIGS. 2-4, operation of fuel tank 22
will now be described. After fuel tank 22 is filled with liquid
fuel, some of the liquid fuel may vaporize due to heat from engine
10 and/or from warm ambient conditions, and such vapors will
collect within vapor space 56 of fuel tank 22. Fuel vapors may
enter baffle space 60 and thence may pass into upper end 82 of vent
tube 78. Thereafter, the fuel vapors may pass through vent fitting
80 and vent conduit 82 into a carbon canister (not shown) or other
containment device, or may be vented directly to the carburetor.
Suitable arrangements for collecting and/or disposing of fuel
vapors which are vented from fuel tanks are disclosed in U.S.
patent application Ser. No. 10/656,305, entitled EMISSIONS CONTROL
SYSTEM FOR SMALL INTERNAL COMBUSTION ENGINES, filed on Sep. 4,
2003; U.S. patent application Ser. No. 11/035,655, entitled
EVAPORATIVE EMISSIONS CONTROL SYSTEM INCLUDING A CHARCOAL CANISTER
FOR SMALL INTERNAL COMBUSTION ENGINES, filed on Jan. 14, 2005; and
U.S. patent application Ser. No. 11/062,955, entitled EVAPORATIVE
EMISSIONS CONTROL SYSTEM FOR SMALL INTERNAL COMBUSTION ENGINES,
filed on Feb. 22, 2005, each assigned to the assignee of the
present invention, the disclosures of which are expressly
incorporated herein by reference.
[0037] Referring to FIG. 5, when the liquid fuel in fuel tank 22 is
agitated, such as during running of engine 22, baffle wall 58
advantageously prevents liquid fuel from entering upper end 82 of
vent tube 78 by blocking the liquid fuel in the manner illustrated
in FIG. 5. Specifically, because baffle wall 58 extends lower than
the upper end 82 of vent tube 78, liquid fuel is blocked from
entering the upper portion of baffle space 60 and the upper end 82
of vent tube 78. Optionally, baffle wall 58 may be elongated, as
represented at 58a in FIG. 4, wherein baffle wall 58a extends
downwardly from upper wall 36 of fuel tank 22 along a substantial
extent of the length of vent tube 78 to further prevent fuel from
being splashed into baffle space 60. For example, baffle wall 58a
may extend to approximately the depth of baffle portion 46 of
filler neck 40 to maintain a vapor/air space within baffle space 60
upon filling fuel into tank 22. In this embodiment, because baffle
wall 58a may extend beneath the level of fuel in tank 22, baffle
wall 58a may include a small vent hole (not shown) near upper wall
36 of fuel tank 22 to allow fuel vapors into baffle space 60 and
thence into vent tube 78.
[0038] Additionally, either in place of or in addition to baffle
wall 58, a fuel blocking element 90 may be positioned within baffle
space 60 to prevent the passage of liquid fuel into vent tube 78
when the fuel in fuel tank 22 is agitated and/or when fuel tank 22
is tipped. For example, as shown in FIG. 5, fuel blocking element
90 may be trapped between upper end 82 of vent tube 78, upper wall
36 of fuel tank 22, and baffle wall 58, or fuel blocking element 90
may have an annular shape and may be disposed between upper end 82
of vent tube 78 and baffle wall 58. Alternatively, fuel blocking
element 90 may be fitted within the open upper end 82 of vent tube
78. Fuel blocking element 90 may be made from an open-cell porous
material which blocks the passage of liquid fuel therethrough yet
allows the passage therethrough of gaseous fuel vapors. For
example, fuel blocking element 90 may be a foam-type material, or
alternatively, may be a porous plastic or porous fiber material of
the type available from Porex.RTM. Porous Products Group, a
division of Porex Corporation of Fairburn, Ga. (Porex.RTM. is a
registered trademark of Porex Technologies Corp.). Still further,
an anti-rollover valve (not shown) may be incorporated into baffle
space 60 and/or into the upper end 82 of vent tube 78 to prevent
liquid fuel from entering vent tube 78 when fuel tank 22 is tipped,
for example. One suitable anti-rollover valve is shown and
described in the above-incorporated U.S. patent application Ser.
No. 11/062,955.
[0039] Under atmospheric pressure conditions, fuel blocking element
90 additionally hinders the passage therethrough of gaseous fuel
vapors and air into vent tube 78. As described above, when a user
fills liquid fuel into fuel tank 22, air is trapped within vapor
space 56 when the level of fuel rises to the lower end, or just
above the lower end, of baffle portion 46 of filler neck 40. The
air trapped within vapor space 56 prevents additional fuel from
entering vapor space 56, and thereafter, any additional liquid fuel
filled into fuel tank 22 rapidly fills up filler neck to indicate
to the user that fuel tank 22 is full. Vapor space 56 also provides
a volume of air within fuel tank 22 in which vapors from the liquid
fuel in fuel tank 22 may collect. In use, if the tank 22 is under
conditions that generate the build-up of gaseous fuel vapors, the
porous construction of fuel blocking element 90 relieves pressure
to atmospheric conditions, whereby gaseous fuel vapors may vent
through vent tube 78, vent fitting 80, and vent conduit 82 into a
carbon canister (not shown) or other containment device, or may be
vent directly to carburetor 20.
[0040] As shown in FIG. 6, fuel tank cap 50 may optionally include
a one-way valve 94 to permit the flow of atmospheric air
therethrough into fuel tank 22, as described below. Valve 94 may be
in the form of a duck-bill or flapper-type valve, for example,
including stem portion 96 anchored to fuel tank cap 50 in a
suitable manner, and flap portion 98 in sealing engagement with
interior wall 100 of fuel tank cap 50 about a passage 102 extending
through fuel tank cap 50. Optionally, a porous element (not shown)
may be provided within passage 102 to trap particulate materials.
In use, as fuel drains from fuel tank 22 during operation of engine
18, atmospheric or make-up air may enter fuel tank 22 through valve
94 as illustrated by the arrows in FIG. 6, wherein vacuum produced
within interior volume 34 of fuel tank 22 as fuel drains therefrom
deflects flap portion 98 away from interior wall 100 of fuel tank
cap 50 to allow atmospheric or make-up air to pass therethrough
through passage 102. Also, if fuel tank 22 is substantially tipped
or is inverted, as shown in FIG. 8 and described below, such as in
connection with tipping lawn mower 10 or another implement with
which fuel tank 22 is used, for example, flap portion 98 of valve
94 sealingly engages interior wall 100 of fuel tank cap 50 to
prevent leakage of fuel through passage 102 in fuel tank cap 50.
When fuel tank cap 50 includes valve 94, pressure associated with
build-up of fuel vapors within fuel tank 22 may escape via vent
tube 78 as necessary.
[0041] Referring to FIGS. 7 and 8, a fuel tank 22 in accordance
with another embodiment is shown which, except as described below,
includes many elements similar to those of fuel tank 22 described
above, and identical references numerals have been used in FIGS. 7
and 8 to identify identical or substantially identical elements
therebetween. Fuel tank 104 includes a relatively planar bottom
wall as opposed to the stepped configuration of lower bottom wall
62, upper bottom wall 64, and transition wall 66 of fuel tank 22
described above. However, fuel tank 22 may also include a stepped
lower wall configuration similar to that of fuel tank 22, if
desired.
[0042] Fuel tank 104 includes vent tube 78 having an upper end
disposed within baffle space 60 of baffle wall 58 similar to fuel
tank 22. However, vent tube 78 of fuel tank 104 includes an
elongated porous fuel blocking element 108 disposed therewithin
which, as shown in FIGS. 7 and 8, may extend from the upper end of
vent tube 78 downwardly within vent tube 78 along a substantial
portion of the length of vent tube 78. Fuel blocking element 108
may be formed of the same or similar materials as fuel blocking
element 90 described above. As shown in FIG. 7, fuel blocking
element 108 includes a conical or sloped upper end portion 110
which may overlap the upper end of vent tube 78 such that any
liquid fuel which contacts upper end portion 110 of fuel blocking
element 108 will flow back down into the main volume of fuel within
fuel tank 104 before a substantial portion of the liquid fuel
enters the porous structure of fuel blocking element 108.
[0043] During normal operation of engine 18, fuel tank 104 is in an
upright orientation as shown in FIG. 7. In this orientation, fuel
blocking element 108 allows the passage of air and fuel vapors
therethrough but blocks the passage of liquid fuel through vent
tube 78 should any liquid fuel splash upwardly into vent space 60.
When lawnmower 10 or another implement with which engine 18 and
fuel tank 22 are used is tipped, such as to an inverted orientation
shown in FIG. 8 or to an angled orientation between the upright
orientation shown in FIG. 7 and the inverted orientation shown in
FIG. 8, the fuel within fuel tank 104 will move by gravity to the
upper end of fuel tank 104. However, in this orientation of fuel
tank 104, the fuel is blocked from leaking outwardly of filler neck
40 by fuel tank cap 50, which may include a one-way valve 94 as
described above with reference to FIG. 6. Also, fuel is prevented
from leaking outwardly of vent tube 78, as vent fitting 80 of vent
tube 78 will be above the level of fuel in tank 22. Fuel blocking
element 108 may be configured to extend within vent tube 78 along a
significant extent of the length of vent tube 78 to substantially
fill the interior of vent tube 78 and to obstruct fuel flow through
vent tube 78 such that, as shown in FIG. 8, the amount of fuel that
can collect in vent tube is minimized. In this manner, even when
fuel tank 104 is inverted, fuel blocking element 108 substantially
prevents liquid fuel from passing therethrough through vent tube
78.
[0044] In a further embodiment (not shown), fuel tank 22 or 104 may
include a horizontal baffle wall toward the upper portion thereof
which includes a plurality of openings therein to allow fuel to be
filled into the lower portion of the fuel tank beneath the baffle
wall. Such baffle wall would provide an additional barrier against
potential splashing of fuel into baffle pace 60 and/or vent tube
78.
[0045] While this invention has been described as having a
preferred design, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
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