VENT VALVE
BACKGROUND
a. Field of Invention
[001] The invention relates generally to a vent valve assembly, including a fill limit vent
valve assembly that is capable of preventing overfilling of a fuel tank and reducing fuel carry-
over during dynamic conditions.
b. Description of Related Art
[002] Fuel level responsive vent valves are conventionally used in vehicle fuel tanks. Vent
valves may employ a float which may close a venting orifice under certain conditions. The
venting orifice of the vent valve may remain open when the fuel is below a certain level and may
close when the fuel reaches the valve. Vent valves may thereby control fuel tank ventilation to
prevent overpressure and vacuum conditions in the fuel tank. Vent valves (i.e., fuel shutoff or
"fill limit" vent valves) may also thereby prevent vapor flow when the fuel level in the fuel tank
reaches a predetermined level in order to create a pressure head within the fuel tank and filler
pipe to operate automatic shutoff and may also prevent liquid fuel from sloshing out of the
venting orifice.
[003] Conventional vent valves may perform at various degrees of effectiveness under
static conditions and dynamic conditions (e.g., during refueling). There is a desire for a vent
valve that is capable of allowing a faster drain of liquid fuel from the vicinity of the venting
orifice in order to prevent residual liquid from being carried into the air stream and out of the
vent valve (i.e., reducing liquid carry-over during dynamic conditions).
SUMMARY
[004] A vent valve assembly comprising a housing, a first venting orifice, a float, and a
second venting orifice is provided. In an embodiment, the vent valve assembly includes a ball-
stop configured to close the second venting orifice to facilitate a pressure differential between the
housing and the fuel tank.

[005] Various features of this invention will become apparent to those skilled in the art
from the following detailed description, which illustrates embodiments and features of this
invention by way of non-limiting examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[006] Embodiments of the invention will now be described, by way of example,with
reference to the accompanying drawings, wherein:
[007] Fig. 1 is a schematic view of a vehicle fuel system employing a valve in accordance
with an embodiment of the invention.
[008] Fig. 2 is a cross-sectional view of a valve in accordance with an embodiment of the
invention.
[009] Fig. 3 is a cross-sectional view of a portion of the valve of Fig. 2, a cone, in
accordance with an embodiment of the invention.
DETAILED DESCRIPTION
[0010] Reference will now be made in detail to embodiments of the present invention,
examples of which are illustrated in the accompanying drawings. While the invention will be
described in conjunction with the embodiments, it will be understood that they are not intended
to limit the invention to these embodiments. On the contrary, the invention is intended to cover
alternatives, modifications and equivalents, which may be included within the spirit and scope of
the invention as embodied in or defined by the appended claims.
[0011] Referring now to Fig. 1 which illustrates a schematic view of a vehicle fuel system,
a fill limit vent valve 10 may be generally mounted in the fuel tank 12 of a vehicle fuel system.
The vehicle fuel system may include a recirculation line 13, a fill cup 15, and a refueling nozzle
17. The vehicle fuel system may also include a fill pipe 14 for introducing fuel into the fuel tank
12 and a vapor recovery system (e.g., vapor canister) 16 to which fuel vapor is vented from the
tank 12 through valve 10 and vent line 18. When the fuel level in the tank 12 is below valve 10,
valve 10 may be open and may provide high volume venting of fuel vapor to vapor recovery
system 16. When liquid fuel reaches valve 10, valve 10 may respond by closing, thereby
shutting off flow to the vapor recovery system 16.

[0012] Referring now to Fig. 2, housing 20 may be provided to house an internal valve
mechanism for valve 10. Housing 20 may be cylindrical or generally cylindrical in shape.
Housing 20 may be molded, for example, from a fuel-resistant plastic, and if desired, may be
mounted in a wall of fuel tank 12. Housing 20 may define a plane (e.g., collar) 22 for allowing
vapor to flow into housing 20 around a float 24 and out first venting orifice 26, as described
further below. When the fuel level reaches a predetermined level at the bottom of housing 20,
vapor flow may be stopped from flowing from the bottom of housing 20. At the predetermined
fuel level, vapor may only flow through a second venting orifice 28.
[0013] First venting orifice 26 may be provided for venting of vapor within valve 10 to
vent recovery system 16. As described below, first venting orifice 26 may be temporarily closed
under certain fuel conditions. When first venting orifice 26 is closed, pressure inside housing 20
may increase, causing pressure in the fuel tank 12 to also increase and eventually shut-off fuel
filling from a fuel pump (not shown).
[0014] The internal valve mechanism of valve 10 may comprise a float 24, seal 30, and
resilient member 32. Float 24 may be provided for closing first venting orifice 26 when the level
of fuel in housing 20 reaches a select or predetermined level. Float 24 may be movable within
housing 20 in order to move up and down in response to the level of fuel in fuel tank 12. In an
embodiment, when the fuel level is at about ¾ of the height of float 24, float 24 may float. Float
24 may be configured and sized so as to move freely up and down in a controlled manner within
housing 20.
[0015] Seal 30 may be provided for closing first venting orifice 26 when the level of fuel
in housing 20 reaches a select or predetermined level. Seal 30 may be connected to float 24.
[0016] Resilient member 32 may be provided for supplying a force (e.g., spring force) to
move float 24 when the level of fuel in housing 20 reaches a select or predetermined level, so
that float 24 may have a range of spring-based motion. In an embodiment, resilient member 32
may comprise a spring. The float 24 and resilient member 32 are biased to closed (i.e., first
venting orifice 26 is closed by float 24) in the presence of a liquid buoyant force. Without the
presence of a liquid (e.g., fuel), float 24 is designed to be heavier than the force of resilient
member 32 so that float 24 may move to an open position (i.e., first venting orifice 26 is open
and is not closed by float 24).

[0017] Second venting orifice 28 may be provided for venting of vapor when the fuel level
in housing 20 reaches a select or predetermined level, such that first venting orifice 26 may be
closed. Accordingly, fuel vapor may continue to vent from housing 20 through second venting
orifice 28. Once the pressure differential between the housing 20 and the fuel tank 12 is
substantially equalized, the weight of float 24 may cause float 24 to move down and open first
venting orifice 26. An operator may then be able to "trickle fill" an additional amount of fuel
under these circumstances. Second venting orifice 28 may be located near the top of housing 20.
Second venting orifice 28 may be in series with first venting orifice 26. Second venting orifice
26 may be smaller in diameter than first venting orifice 26. For example, in an embodiment,
second venting orifice 28 may be between approximately 1.5 and 3 mm in diameter. Because
second venting orifice 28 may be smaller than first venting orifice 26 or because second venting
orifice 26 may be closed, a pressure differential may develop between fuel tank 12 and the
interior of housing 20 during refueling. This pressure differential may cause liquid fuel to enter
the bottom of housing 20, thereby causing float 24 to rise and close first venting orifice 26,
which opens to the vent recovery system 16. The stopping of vapor flow through first venting
orifice 26 can cause the pressure of fuel tank 12 to rise, causing the fuel level to rise in fill pipe
14. When the refueling nozzle 17 is reached, refueling may be shut-off. This method for fuel
shut-off may be generally referred to as "dip tube shut off." In order to prevent operator "trickle-
fill," in which operators attempt to add additional fuel into fuel tank 12 after initial shut-off, the
size of second venting orifice 28 maybe relatively small in comparison to the size of first
venting orifice 26. Second venting orifice 28 may even be closed in an embodiment under
certain conditions. For example, in an embodiment, second venting orifice 28 may be closed
when a vehicle is in a stopped position. The period of time between each "trickle-fill" may be
determined by the size of second venting orifice 28. Accordingly, modification to the size of
second venting orifice 28 may either decrease or increase the period of time between shut-off
clicks during trickle-fill. For some applications, it may be desirable to provide a smaller second
venting orifice 28 since the longer it takes to permit pressure equalization between housing 20
and fuel tank 12, the less "trickle-fill" may be allowed during refueling. If second venting orifice
28 is closed, some pressure may be retained in fuel tank 12 which may help limit "trickle-fill."
[0018] Second venting orifice 28 may be provided to reduce carryover during dynamic
conditions (e.g., refueling) by preventing residual liquid (e.g., fuel) from being carried into the

vapor stream and carried out of the vent valve 10. In order to better allow gravity to remove
liquid (e.g., fuel) from the inside of housing 20, the vapor must be allowed to replace the
escaping liquid. Accordingly, second venting orifice 28 may allow vapor to replace the escaping
liquid providing a quicker drain of liquid. To provide for a quicker drain of fluid from housing
20, the size of second venting orifice 28 may be of an increased size than is desirable for
controlling "trickle-fill." In other words, the desired size of second venting orifice 28 for
improving drainage of fluid from housing 20 (in order to prevent residual liquid from being
carried into the vapor stream) may be counterbalanced by the desired size of second venting
orifice 28 for controlling "trickle-fill."
[0019] Stop 36 may be configured to close second venting orifice 28 to facilitate a
pressure differential between the housing 20 and the fuel tank 12. Stop 36 may therefore modify
the size of second venting orifice 28 and optimize the size of second venting orifice 28
depending upon whether second venting orifice 28 is being used to control "trickle-fill" or is
being used to improve drainage of fuel from housing 20 in order to prevent residual liquid from
being carried into the vapor stream. For example, second venting orifice 28 may be larger during
dynamic conditions (e.g., refueling) because the means 34 for closing the second venting orifice
28 may not be engaged. The larger size of second venting orifice 28 may allow liquid (e.g., fuel)
to drain faster under dynamic conditions by allowing a greater amount of vapor to enter housing
20 and more quickly remove liquid from inside housing 20. During static (i.e., non-dynamic)
conditions, means 34 for closing second venting orifice 28 may be engaged in order to close
second venting orifice 28. The closing of second venting orifice 28 may facilitate a pressure
differential between fuel tank 12 and the interior of housing 20 in order to assist with controlling
"trickle-fill."
[0020] Stop 36 may be disposed above second venting orifice 28. Stop 36 may comprise
steel. In an embodiment, stop 36 may comprise a ball-stop. Stop 36 may be generally spherical
in shape. If stop 36 is spherical, it may move easily when a vehicle is in motion. Stop 36 may
be configured in size and shape so as to close second venting orifice 28. In an embodiment, stop
36 may be approximately between about 8.7 mm and about 12.7 mm (i.e., about u/32 and about
V2 inches) in diameter.
[0021] Cone 38 may be provided for housing stop 36. Cone 38 may define second venting
orifice 28. Cone 38 may be configured in size and shape so as to retain stop 36. In an

embodiment, cone 38 may be configured in size and shape so as to cause stop 36 to return to the
center of cone 38 when the vehicle in which valve 10 is used is not moving. Cone 38 may
comprise nylon or an acetal resin engineering plastic such as that sold by DuPont under the brand
name DELRIN®. Referring now to Fig. 3, a cross-sectional view of a cone 38 is illustrated. In
the illustrated embodiment, cone 38 may be approximately 0.875 mm in cross-sectional width
and may define a top orifice 42 of approximately 0.625 mm in diameter. Cone 38 may be
approximately 1.50 mm in height and may define an interior height 44 of approximately 0.75
mm. The interior bottom 46 of cone 38 may taper radially inwardly at an approximately 5° angle
a toward an internal orifice 48 of approximately 0.100 mm in width. In an embodiment, angle a
may range between approximately 3° and 10°. The distance from the top 50 of cone 38 to a
midpoint 52 of second venting orifice 28 maybe approximately 1.125 mm. Although these
measurements are described in detail, it is understood by those of ordinary skill in the art that
numerous other measurements may be used in connection with cone 38 and remain within the
spirit and scope of the invention.
[0022] If desired, a third venting orifice 40 may be included in housing 20 for permitting
venting of fuel tank 12 at certain pressures in valve 10. Third venting orifice 40 may be in
parallel with second venting orifice 28, and may include a head valve (not shown) for opening
third venting orifice 40 at selected pressures in valve 10. For example, third venting orifice 40
may be opened to vent fuel tank 12 at tank pressures above fill conditions.
[0023] The foregoing descriptions of specific embodiments of the present invention have
been presented for purposes of illustration and description. They are not intended to bg
exhaustive or to limit the invention to the precise forms disclosed, and various modifications and
variations are possible in light of the above teaching. The embodiments were chosen and
described in order to explain the principles of the invention and its practical application, to
thereby enable others skilled in the art to utilize the invention and various embodiments with
various modifications as are suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the claims and their equivalents.

We Claim:
1. A vent valve assembly (10) at least partially disposed within an interior of a fuel
tank (12), the vent valve assembly (10) comprising:
a housing (20), the housing (20) defining a chamber;
a first venting orifice (26) located in the housing (20) for venting of vapor from
the housing (20);
a float (24) disposed within the chamber configured to close the first venting
orifice (26) when the level of fuel in the housing (20) reaches a predetermined level;
a second venting orifice (28) in fluid communication with the chamber, the
second venting orifice (28) for venting of the vapor from the housing (20) or for allowing vapor
to enter the housing (20); and
a stop (36) configured to close the second venting orifice (28) to facilitate a
pressure differential between the housing (20) and the fuel tank (12).
2. A vent valve assembly (10) in accordance with claim 1, wherein the housing (20)
includes a plane (22) for allowing vapor to flow into the housing around the float (24) and out
the first venting orifice (26).
3. A vent valve assembly (10) in accordance with claim 1, wherein the float (24)
closes the first venting orifice (26) in response to a predetermined level of fuel through an
increased buoyancy force.
4. A vent valve assembly (10) in accordance with claim 1, wherein the first venting
orifice (26) is connected to a vapor recovery system (16).
5. A vent valve assembly (10) in accordance with claim 1, further comprising a seal
(30) connected to the float (24) for closing the first venting orifice (26) when the level of fuel in
the housing (20) reaches a predetermined level.
6. A vent valve assembly (10) in accordance with claim 1, wherein the second
venting orifice (28) is located at or near the top of the housing (20).

7. A vent valve assembly (10) in accordance with claim 1, wherein the second
venting orifice (28) is in series with the first venting orifice (26).
8. A vent valve assembly (10) in accordance with claim 1, wherein the second
venting orifice (28) is smaller in diameter than the first venting orifice (26).
9. A vent valve assembly (10) in accordance with claim 1, wherein the second
venting orifice (28) is between approximately 1.5 and 3 mm in diameter.
10. A vent valve assembly (10) in accordance with claim 1, wherein the stop (36) is
disposed above the second venting orifice (28).
11. A vent valve assembly (10) in accordance with claim 1, wherein the stop (36)
comprises steel.
12. A vent valve assembly (10) in accordance with claim 1, wherein the stop (36) is
spherical.
13. A vent valve assembly (10) in accordance with claim 1, further comprising a cone
(38) for housing the stop (36).
14. A vent valve assembly (10) in accordance with claim 13, wherein the cone (38)
comprises nylon or an acetal resin engineering plastic.
15. A vent valve assembly (10) in accordance with claim 10 wherein the interior
bottom (46) of the cone (38) tapers radially inwardly at an angle (a) between approximately 3° to
10°.
16. A vent valve assembly (10) in accordance with claim 1, further comprising a
resilient member (32) for providing a spring force to move the float (24).
17. A vent valve assembly (10) in accordance with claim 1, further comprising a third
venting orifice (40) disposed in the housing (20).
18. A vent valve assembly (10) in accordance with claim 17, wherein the third
venting orifice (40) is in parallel with the second venting orifice (28).

19. A vent valve assembly (10) in accordance with claim 18, wherein the third
venting orifice (40) includes a head valve for opening the third venting orifice (40) at selected
pressures in the vent valve assembly (10).
20. A vent valve assembly (10) at least partially disposed within an interior of a fuel
tank (12), the vent valve assembly (10) comprising:
a housing (20), the housing (20) defining a chamber;
a first venting orifice (26) located in the housing (20) for venting of vapor from
the housing (20);
a means for closing the first venting orifice (26) when the level of fuel in the
housing (20) reaches a predetermined level;
a means for providing a spring force to activate the means for closing the first
venting orifice (26) when the level of fuel in the housing (20) reaches a predetermined level;
a second venting orifice (28) in fluid communication with the chamber, the
second venting orifice (28) for venting of the vapor from the housing (20) or for allowing vapor
to enter the housing (20); and
a means for closing the second venting orifice (28) to facilitate a pressure
differential between the housing (20) and the fuel tank (12).
21. A vent valve assembly (10) in accordance with claim 20, wherein the means for
closing the second venting orifice (28) comprises a ball (36) disposed in a cone (38).
22. A vent valve assembly (10) at least partially disposed within an interior of a fuel
tank (12), the vent valve assembly (10) comprising:
a housing (20), the housing (20) defining a chamber;
a first venting orifice (26) located in the housing (20) for venting of vapor from
the housing (20) to a vapor recovery system (16);
a float (24) disposed within the chamber, the float (24) including a seal (30)
configured to close the first venting orifice (26) through an increased buoyancy force when the
level of fuel in the housing (20) reaches a predetermined level;

a second venting orifice (28) located at or near the top of the housing (20),
wherein the second venting orifice (28) is in fluid communication with the chamber, is in series
with the first venting orifice (26), and is smaller in diameter than the first venting orifice (26);
a ball-stop (36) disposed above the second venting orifice (28) and configured to
close the second venting orifice (28) to facilitate a pressure differential between the housing (20)
and the fuel tank (12); and
a third venting orifice (40) disposed in the housing (20), the third venting orifice
(40) in parallel with the second venting orifice (28) and including a head valve for opening the
third venting orifice (40) at selected pressures in the vent valve assembly (10),
wherein the housing (20) includes a plane (22) for allowing vapor to flow into the
housing (20), around the float (24), and out the first venting orifice (26).

ABSTRACT

A vent valve assembly (10) at least partially disposed
within an interior of a fuel tank (12) is provided. The
vent valve assembly (10) comprises a housing (20), a
first venting orifice (26), a float (24) configured to
close the first venting orifice (26) when the level of
fuel in the housing (20) reaches a predetermined level,
a second venting orifice (28), and a stop (36)
configured to close the second venting orifice (28) to
facilitate a pressure differential between the housing
(20) and the fuel tank (12).