FUEL VAPOR VENT VALVE WITH DYNAMIC PRESSURE RELIEF
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit if U.S. Provisional Patent Application
Serial No. 61/176,998, filed on May 11, 2009, the disclosure of which is hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The invention generally relates to a fuel vapor vent valve assembly, and
more specifically to an anti-trickle valve for the fuel vapor vent valve assembly.
BACKGROUND
[0003] Fuel storage systems for vehicles include a fuel tank. The fuel tank
includes an inlet, to which a filler pipe is attached, through which fuel is dispensed into
the tank. The fuel tank further includes an outlet, through which fuel is directed to an
engine. The fuel tank may further include a fuel vapor vent valve assembly, disposed
on a top wall of the fuel tank. The fuel vapor vent valve assembly provides an outlet to
vent fuel vapors from within an interior of the fuel tank.
[0004] During refueling of the fuel tank, operation of the vehicle, or as a result
of temperature change of the fuel, the vapor pressure within the tank may change, i.e.,
increase or decrease. The fuel vapor vent valve assembly vents the fuel vapor from
within the fuel tank to maintain a vapor head within a predetermined range when the
vapor pressure rises above the predetermined range. The fuel vapor vent valve
assembly may further include a liquid/vapor discriminator, commonly referred to as a
roll-over valve. The liquid/vapor discriminator is configured to allow the fuel vapors
to pass through the fuel vapor vent valve assembly during normal operating conditions,
but is configured to block fluid communication between the fuel tank and the fuel vapor
vent valve assembly when the fuel tank is oriented at an extreme angle or upside down,
such as in the event of a vehicular roll-over. The fuel tank may further include a

vacuum relief valve, which is configured to relieve a vacuum pressure from within the
fuel tank.
SUMMARY
[0005] A fuel vapor vent valve assembly for a fuel tank of a vehicle is provided.
The vent valve assembly includes a housing having an outlet, and defining an interior
opening. The interior opening is in fluid communication with the outlet. The fuel
vapor vent valve assembly further includes a liquid/vapor discriminator coupled to the
housing. The liquid/vapor discriminator is movable between an open position and a
closed position. When in the open position, the liquid/vapor discriminator allows fluid
communication between an interior of the fuel tank and the interior opening of the
housing. When in the closed position, the liquid/vapor discriminator prevents fluid
communication between the interior of the fuel tank and the interior opening of the
housing. The fuel vapor vent valve assembly further includes an anti-trickle valve
disposed within the interior opening of the housing. The anti-trickle valve opens and
closes fluid communication between the interior opening of the housing arid the
liquid/vapor discriminator to selectively allow fluid communication between the interior
opening of the housing and the interior of the fuel tank when the liquid/vapor
discriminator is in the open position. The anti-trickle valve includes a dynamic
pressure relief mechanism, which includes a movable element. The movable element
opens fluid communication between the interior opening of the housing and the
liquid/vapor discriminator in response to a change in motion, to vent vapor pressure
from the interior of the fuel tank.
[0006] An anti-trickle valve for a fuel vapor vent assembly of a fuel tank of a
vehicle is also provided. The anti-trickle valve includes a casing including an upper
portion and a lower portion. The upper portion defines an upper dynamic vapor
passage and an upper vacuum relief vapor passage. The lower portion defines a lower
dynamic vapor passage and a lower vacuum relief vapor passage. The upper portion
and the lower portion of the casing cooperate to define a first cavity in fluid
communication with the upper dynamic vapor passage and the lower dynamic vapor

passage, and a second cavity in fluid communication with the upper vacuum relief
vapor passage and the lower vacuum relief vapor passage. The anti-trickle valve
further includes a float disposed within the second cavity. The float seals against the
upper vacuum relief vapor passage when a vapor pressure in the fuel tank exceeds a
predetermined value. The float also withdraws from sealing engagement with the upper
vacuum relief vapor passage when a vacuum pressure from within the fuel tank falls
below the predetermined value to open fluid communication between the upper vacuum
relief vapor passage and the lower vacuum relief vapor passage. The anti-trickle valve
further includes a movable element disposed within the first cavity. The movable
element opens fluid communication between the upper dynamic vapor passage and the
lower dynamic vapor passage in response to a change in motion, to vent vapor pressure
from within the fuel tank during movement of the vehicle,
[0007] Accordingly, the movable element allows the anti-trickle valve to vent
fuel vapors from within the fuel tank in response to movement of the vehicle. As the
vapor pressure within the tank rises during operation of the vehicle, for example, by the
fuel sloshing and/or an increase in temperature of the fuel, the movable element moves
within the first cavity to open fluid communication between the upper dynamic vapor
passage and the lower dynamic vapor passage. Once the vehicle comes to rest, the
movable element moves back into sealing engagement with me lower dynamic vapor
passage to close fluid communication between the upper dynamic vapor passage and the
lower dynamic vapor passage.
[0008] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of the
best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is a schematic cross sectional view of a fuel vapor vent valve
assembly.

[0010] Figure 2 is an enlarged partial schematic cross sectional view of the fuel
vapor vent valve assembly, showing an anti-trickle valve in a first position.
[0011] Figure 3 is an enlarged partial schematic cross sectional view of the fuel
vapor vent valve assembly, showing the anti-trickle valve in a second position.
[0012] Figure 4 is a schematic perspective cross sectional view of the anti-
trickle valve when at rest and subjected to a vacuum pressure.
[0013] Figure 5 is a schematic perspective cross sectional view of the anti-
trickle valve during a change in motion and subjected to a positive vapor pressure.
DETAILED DESCRIPTION
[0014] Referring to the Figures, wherein like numerals indicate like parts
throughout the different views, a fuel vapor vent valve assembly is shown generally at
20. The fuel vapor vent valve assembly 20 is for a fuel tank 22 of a vehicle (not
shown). The fuel vapor vent valve assembly 20 controls the flow of vapors out of and
into the fuel tank 22 to regulate a vapor pressure head within an interior 21 of the fuel
tank 22. Accordingly, the fuel vapor vent valve assembly 20 releases fuel vapors
and/or air from within the fuel tank 22 to vent the fuel tank 22 and permits air flow into
the fuel tank 22 in response to a vacuum pressure within the fuel tank 22.
[0015] Referring to Figure 1, the fuel vapor vent valve assembly 20 includes a
housing 24. The housing 24 defines an outlet 26, a vapor port 28, and an interior
opening 30 in fluid communication with the outlet 26 and the vapor port 28. The outlet
26 may be, but is not required to be, connected to some other component, such as a vapor
canister (not shown). However, the outlet 26 is maintained at atmospheric pressure. Any
vapors vented from the fuel tank 22 are exhausted through the outlet 26. The vapor port
28 is in fluid communication with fuel tank 22. The interior opening 30 of the housing
24 is disposed between the outlet 26 and the vapor port 28.
[0016] The fuel vapor vent valve assembly 20 includes a liquid/vapor
discriminator 32a, 32b, commonly referred to as a roll-over valve. The liquid/vapor
discriminator 32a, 32b is coupled to the housing 24, adjacent to and in fluid
communication with the vapor port 28. Accordingly, the vapor port 28 connects the

interior opening 30 of the housing 24 and the liquid/vapor discriminator 32a, 32b. The
liquid/vapor discriminator 32a, 32b is movable between an open position and a closed
position. When in the open position, the liquid/vapor discriminator 32a, 32b allows
fluid communication, particularly vapor communication, between an interior of the fuel
tank 22 and the interior opening 30 of the housing 24. When in the closed position, the
liquid/vapor discriminator 32a, 32b is configured to prevent fluid communication,
including vapor communication, between the interior of the fuel tank 22 and the interior
opening 30 of the housing 24. The liquid/vapor discriminator 32a, 32b operates to
prevent liquid fuel spillage from the fuel tank 22 when the fuel tank 22 is disposed at
extreme angles or upside-down, such as during a roll-over event. The liquid/vapor
discriminator 32a, 32b may be designed and/or configured in any suitable manner tht
restricts liquid fuel from spilling from the fuel tank 22 when the fuel tank is disposed
at an extreme angle or upside down.
[0017] As shown, the fuel vapor vent valve assembly 20 includes a first
liquid/vapor discriminator 32a and a second liquid/vapor discriminator 32b. The first
liquid/vapor discriminator 32a and the second liquid/vapor discriminator 32b are
vertically offset from each other to open and/or close fluid communication between the
fuel tank 22 and the interior opening 30 of the housing 24 at different fuel levels within
the fuel tank 22. However, it should be appreciated that the fuel vapor vent assembly
need not include both the first liquid/vapor discriminator 32a and the second liquid/vapor
discriminator 32b. Furthermore, it should be appreciated that the first liquid/vapor
discriminator 32a and the second liquid/vapor discriminator 32b, need not both be
disposed in the housing 24, i.e, the first liquid/vapor discriminator 32a and the second
liquid/vapor discriminator 32b may be separate and independent units.
[0018] Referring also to Figures 2 through 4, the fuel vapor vent valve assembly
20 further includes an anti-trickle valve 34. The anti-trickle valve 34 is disposed within
the interior opening 30 of the housing 24. The anti-trickle valve 34 opens and closes
fluid communication between the interior opening 30 of the housing 24 and the first
liquid/vapor discriminator 32a when the first liquid/vapor discriminator 32a is in the
open position. The anti-trickle valve 34 opens and closes fluid communication,

particularly vapor communication, to selectively allow fluid communication, i.e., vapor
communication, between the interior opening 30 of the housing 24 and the interior of
the fuel tank 22.
[0019] The anti-trickle valve 34 operates to prevent overfilling of the fuel tank
22, particularly when a low vapor pressure exists within the fuel tank 22. For example,
during refueling of the fuel tank 22, when the second liquid/vapor discriminator 32b is
completely closed due to a rise in the incoming fuel level, the anti-trickle valve 34
blocks the vapor port 28 to the first liquid/vapor discriminator 32a to prevent "trickle
fill" of fuel into the fuel tank 22, and thereby prevent overfilling of the fuel tank 22.
[0020] The anti-trickle valve 34 includes a casing 36 defining a first cavity 38
and a second cavity 40 that is separate from the first cavity 38. The casing 36 may
include a bottom portion 42 and an upper portion 44, with the upper portion 44
securely affixed to the bottom portion 42. The upper portion 44 and the bottom portion
42 cooperate to define the first cavity 38 and the second cavity 40.
[0021] The casing 36 defines an upper dynamic vapor passage 46a, 46b and a
lower dynamic vapor passage 48. The upper dynamic vapor passage 46a, 46b is
configured for communicating vapor between the interior opening 30 of the housing 24
and the first cavity 38. The lower dynamic vapor passage 48 is configured for
communicating vapor between the first cavity 38 and the vapor port 28, and thereby to
the liquid/vapor discriminator 32a. As shown, the upper dynamic vapor passage 46a,
46b may include, but is not limited to, a first upper dynamic vapor passage 46a and a
second upper dynamic vapor passage 46b. The second upper dynamic vapor passage
46b is laterally offset and spaced from the first upper dynamic vapor passage 46a.
[0022] The casing 36 further defines an upper vacuum relief vapor passage 50
and a lower vacuum relief vapor passage 52a, 52b. The upper vacuum relief vapor
passage 50 is configured for communicating vapor between the interior opening 30 of
the housing 24 and the second cavity 40. The lower vacuum relief vapor passage 52a,
52b communicates vapor between the second cavity 40 and the vapor port 28, and
thereby to the liquid/vapor discriminator 32. As shown, the lower vacuum relief vapor
passage 52a, 52b may include, but is not limited to, a first lower vacuum relief vapor

passage 52a and a second lower vacuum relief vapor passage 52b. The second lower
vacuum relief vapor passage 52b is laterally offset and spaced from the first lower
vacuum relief vapor passage 52a.
[0023] As shown, the bottom portion 42 of the casing 36 defines the lower
dynamic vapor passage 48 and the lower vacuum relief vapor passage 52a, 52b, and the
upper portion 44 defines the upper dynamic vapor passage 46a, 46b and the upper
vacuum relief vapor passage 50. However, it should be appreciated that the casing 36
may be configured differently than as shown and described herein.
[0024] The anti-trickle valve 34 includes a dynamic pressure relief mechanism
54. The dynamic pressure relief mechanism 54 includes a movable element 56. The
movable element 56 is configured for opening fluid communication, particularly vapor
communication, between the interior opening 30 of the housing 24 and the vapor port
28, and more specifically with the liquid/vapor discriminator 32, in response to a
change in motion. The movable element 56 opens fluid communication in response to
movement of the vehicle to vent vapor pressure from the interior of the fuel tank 22
during movement of the vehicle. Accordingly, as vapor pressure builds during
movement of the vehicle, for example, by the mixing of the fuel with the air in the fuel
tank 22, or with an increased temperature of the fuel within the fuel tank 22, the
movable element 56 moves to open vapor communication between interior opening 30
of the housing 24 and the fuel tank 22 to vent the increased vapor pressure.
[0025] The movable element 56 is disposed within the first cavity 38. As
shown, the movable element 56 may include, but is not limited to, a spherical element.
For example, movable element 56 may include a stainless steel ball. However, it
should be appreciated that the movable element 56 may be configured other than shown
and described herein.
[0026] The casing 36 of the anti-trickle valve 34 includes a concave ramp 58.
More specifically, an upper surface 60 of the lower portion of the casing 36 defines the
concave ramp 58. The concave ramp 58 is concentric with the lower dynamic vapor
passage 48. As shown in Figure 4, the concave ramp 58 centers the movable element
56 over the dynamic vapor passage when the vehicle is at rest. As such, when there is

ball or the like. As shown, the upper vacuum relief vapor passage 50 includes a
circular port. As shown in Figure 5, the float 64 is configured to seal against the
circular port of the upper vacuum relief vapor passage 50 in response to the vapor
pressure from within the fuel tank 22 having a value greater than a selected vacuum
level, such as 0 kPa, to bias the float 64 upwards. Accordingly, when the vapor
pressure at the vapor port 28, and more specifically when the vapor pressure at the fuel
tank 22, is greater than 0 kPa in this example, the vapor pressure moves the float 64
into sealing engagement with the upper vacuum relief vapor passage 50 to block fluid
communication, particularly vapor communication, between the interior opening 30 of
the bousing 24 and the fuel tank 22. As shown in Figure 4, the float 64 is configured
to withdraw from sealing engagement with the circular port of the upper vacuum relief
vapor passage 50 in response to a vacuum pressure from within the fuel tank 22, which
draws the float 64 downwards to open fluid communication between the upper vacuum
relief vapor passage 50 and the lower vacuum relief vapor passage 52a, 52b.
Accordingly, when a selected vacuum pressure level, i.e., a pressure less than 0 kPa,
exists at the vapor port 28, and more specifically within the fuel tank 22, then the
vacuum pressure draws the float 64 vertically downward away from and out of sealing
engagement with the upper vacuum relief vapor passage 50, thereby opening fluid
communication, and particularly vapor communication, between the interior opening 30
of the housing 24 and the fuel tank 22 to permit air to enter the fuel tank 22 and fill the
vacuum.
[0030] As shown in Figures 4 and 5, the casing 36 may include a plurality of
ribs 66 radially spaced about and adjacent the lower vacuum relief vapor passage 52a,
52b. More specifically, the upper surface 60 of the lower portion of the casing 36
defines the ribs 66. The ribs 66 vertically space the float 64 from the lower vacuum
relief vapor passage 52a, 52b when the float 64 is drawn vertically downward by a
vacuum pressure. As such, the ribs 66 prevent the vacuum pressure from drawing the
float 64 downward into sealing engagement with the lower vacuum relief vapor passage
52.

[0031] Referring back to the embodiment in Figures 2 and 3, the housing 24
includes a ridge 68 disposed circumferentially about the vapor port 28, the lower
dynamic vapor passage 48 and the lower vacuum relief vapor passage 52a, 52b. It
should be appreciated that the ridge 68 may include any suitable shape, including but
not limited to, a circular shape or a rectangular shape.
[0032| The anti-trickle valve 34 is movable between a first position, shown in
Figure 2, and a second position, shown in Figure 3. When in the first position, the
anti-trickle valve 34 is disposed in sealing engagement with the ridge 68 to seal the
vapor port 28, the lower dynamic vapor passage 48 and the lower vacuum relief vapor
passage 52a, 52b from the interior opening 30 of the housing 24. When in the second
position, the anti-trickle valve 34 is vertically spaced from the ridge 68 to permit fluid
communication, and particularly vapor communication, around a periphery of the anti-
trickle valve 34 between the vapor port 28 and the outlet 26. The housing 24 may
define a plurality of flow channels (not shown) disposed about the periphery of the
casing 36 to facilitate fluid communication around the periphery of the anti-trickle valve
34.
[0033] The fuel vapor vent valve assembly 20 further includes a biasing device
70. The biasing device 70 is configured for biasing the anti-trickle valve 34 into the
first position. The biasing device 70 may include, but is not limited to, a coil spring or
the like. The biasing device 70 has a stiffness sufficient to resist movement of the anti-
trickle valve 34 when it responds to a vapor pressure from within the fuel tank 22
having a value less than a first predetermined value (e.g., less than 3 kPa).
Accordingly, if the vapor pressure within the fuel tank 22 and at the vapor port 28 is
less than 3 kPa, then the biasing device 70 maintains the anti-trickle valve 34 in the first
position. However, if the vapor pressure within the fuel tank 22 and at the vapor port
28 rises to above 3 kPa, then the pressure exerted on the anti-trickle valve 34 from the
vapor pressure is sufficient to move the biasing device 70, e.g., compress the coil
spring, and move the anti-trickle valve 34 into me second position. When in the second
position, large quantities of vapor from within me fuel tank 22 may escape in a short
amount of time.

[0034] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.

WE CLAIM
1. A fuel vapor vent valve assembly (20) for a fuel tank (22), the
fuel vapor vent valve assembly (20) comprising:
a housing (24) including an outlet (26) and defining an interior opening
(30) in fluid communication with the outlet (26);
a liquid/vapor discriminator (32a) coupled to the housing (24) and
movable between an open position and a closed position, wherein the liquid/vapor
discriminator (32a) allows fluid communication between an interior of the fuel tank (22)
and the interior opening (30) of the housing (24) in the open position, and the
liquid/vapor discriminator (32a) prevents fluid communication between the interior of
the fuel tank (22) and the interior opening (30) of the housing (24) in the closed
position; and
an anti-trickle valve (34) disposed within the interior opening (30) of the
housing (24) opens and closes fluid communication between the interior opening (30) of
the housing (24) and the liquid/vapor discriminator (32a) to selectively allow fluid
communication between the interior opening (30) of the housing (24) and the interior of
the fuel tank (22) when the liquid/vapor discriminator (32a) is in the open position;
wherein the anti-trickle valve (34) includes a dynamic pressure relief
mechanism (54) having a movable element (56) that opens fluid communication
between the interior opening (30) of the housing (24) and the liquid/vapor discriminator
(32a) in response to a change in motion of the moveable element (56) to vent vapor
pressure from the interior of the fuel tank (22).
2. A fuel vapor vent valve assembly (20) as set forth in claim 1
wherein the anti-trickle valve (34) includes a casing (36) defining a first cavity (38),
with the movable element (56) disposed within the first cavity (38).
3. A fuel vapor vent valve assembly (20) as set forth in claim 2
wherein the casing (36) defines an upper dynamic vapor passage (46a, 46b) and a lower

dynamic vapor passage (48), with the upper dynamic vapor passage (46a, 46b)
configured for communicating vapor between the interior opening (30) of the housing
(24) and the first cavity (38), and the lower dynamic vapor passage (48) configured for
communicating vapor between the first cavity (38) and the liquid/vapor discriminator
(32a).
4. A fuel vapor vent valve assembly (20) as set forth in claim 3
wherein the casing (36) includes a concave ramp (58) concentric with the lower
dynamic vapor passage (48) and configured for centering the movable element (56)
over the dynamic vapor passage when at rest, with the movable element (56) movable
upward along the concave ramp (58) in response to a change in motion to open fluid
communication between the upper dynamic vapor passage (46a, 46b) and the lower
dynamic vapor passage (48).
5. A fuel vapor vent valve assembly (20) as set forth in claim 4
wherein the movable element (56) includes a spherical element.
6. A fuel vapor vent valve assembly (20) as set forth in claim 5
wherein the movable element (56) includes a mass sufficient to resist movement up the
concave ramp (58) by vapor pressure having a value greater than a predetermined level.
7. A fuel vapor vent valve assembly (20) as set forth in claim 1
wherein the anti-trickle valve (34) includes a vacuum relief mechanism (62) that
provides fluid communication between the interior opening (30) of the housing (24) and
the liquid/vapor discriminator (32a) to relieve a vacuum pressure within the fuel tank
(22).
8. A fuel vapor vent valve assembly (20) as set forth in claim 7
wherein the casing (36) defines a second cavity (40) separate from the first cavity (38).

9. A fuel vapor vent valve assembly (20) as set forth in claim 8
wherein the vacuum relief mechanism (62) includes a float (64) disposed within the
second cavity (40).
10. A fuel vapor vent valve assembly (20) as set forth in claim 9
wherein the casing (36) defines an upper vacuum relief vapor passage (50) and a lower
vacuum relief vapor passage (52a, 52b), with the upper vacuum relief vapor passage
(50) configured for communicating vapor between the interior opening (30) of the
housing (24) and the second cavity (40), and the lower vacuum relief vapor passage
(52a, 52b) configured for communicating vapor between me second cavity (40) and the
liquid/vapor discriminator (32a).
11. A fuel vapor vent valve assembly (20) as set forth in claim 10
wherein the upper vacuum relief vapor passage (50) includes a circular port and the
float (64) includes a spherical element, wherein the float (64) is configured to seal
against the circular port of the upper vacuum relief vapor passage (50) in response to a
vapor pressure from within the fuel tank (22) exceeding a selected vacuum level, and
the float (64) is configured to withdraw from sealing engagement with the circular port
of the upper vacuum relief vapor passage (50) in response to a vacuum pressure from
within the fuel tank (22) less than the selected vacuum level, to open fluid
communication between me upper vacuum relief vapor passage (50) and the lower
vacuum relief vapor passage (52a, 52b).
12. A fuel vapor vent valve assembly (20) as set forth in claim 11
wherein the casing (36) includes a plurality of ribs (66) radially spaced about and
adjacent the lower vacuum relief vapor passage (52a, 52b).
13. A fuel vapor vent valve assembly (20) as set forth in claim 2
wherein the housing (24) defines a vapor port (28) interconnecting the interior opening
(30) and the liquid/vapor discriminator (32a).

14. A fuel vapor vent valve assembly (20) as set forth in claim 13
wherein the housing (24) includes a ridge (68) disposed circumferentially about the
vapor port (28), the lower dynamic vapor passage (48) and the lower vacuum relief
vapor passage (52a, 52b), wherein the anti-trickle valve (34) is movable between a first
position where the anti-trickle valve (34) is in sealing engagement with the ridge (68) to
seal the vapor port (28), the lower dynamic vapor passage (48) and the lower vacuum
relief vapor passage (52a, 52b) from the interior opening (30) of the housing (24), and
a second position where the anti-trickle valve (34) is spaced from the ridge (68) to
permit fluid communication around a periphery of the anti-trickle valve (34) between
the vapor port (28) and the outlet (26).
15. A fuel vapor vent valve assembly (20) as set forth in claim 14
further including a biasing device (70) configured for biasing the anti-trickle valve (34)
into the first position, and including a stiffness sufficient to resist movement of the anti-
trickle valve (34) in response to a vapor pressure from within the fuel tank (22) having
a value less than a predetermined level.

A fuel vapor vent valve assembly (20) includes an anti-triekle valve (34)
having a casing (36) defining a first cavity (38). A movable element (56) is disposed
within the first cavity (38). The casing (36) defines a lower dynamic vapot passage (48)
in fluid communication with an interior of a fuel tank (22). A concave ramp (58) is
disposed concentrically about the lower dynamic vapor passage (48), within the first
cavity (38). The movable element (56) moves upward along the concave ramp (58) in
response to a change in motion to open fluid communication through the lower dynamic
vapor passage (48) to vent vapor pressure from within the fuel tank (22) during
movement.