VALVE ASSEMBLY FOR HIGH-PRESSURE FLUID RESERVOIR
CROSS-REFERENCE TO RELATED APPLICATION(S)
[001] This application claims the benefit of U.S. Provisional Application Serial
No. 61/171,548 filed April 22, 2009, the entire contents of which is hereby
incorporated by reference.
TECHNICAL FIELD
[002] The present invention relates to a valve assembly for controlling fluid flow to
and from a high-pressure reservoir.
BACKGROUND OF THE INVENTION
[003] Valves are employed in a multitude of industries to control flow of liquids
and/or gases. One application for such control valves appears in vehicles with stored
fuel to control a vehicle's evap orative emissions resulting from gasoline vapors
escaping from the vehicle's fuel system. Evaporative emissions of modern vehicles are
strictly regulated in many countries. To prevent fuel vapors from venting directly to
the atmosphere, a majority of vehicles manufactured since the 1970's include
specifically designed evaporative emissions systems. Additionally, in recent years
vehicle manufacturers began developing fully sealed fuel delivery to their engines.
[004] In a typical evaporative emissions system, vented vapors from the fuel
system are sent to a purge canister containing activated charcoal. The activated
charcoal used in such canisters is a form of carbon that has been processed to make it
extremely porous, creating a very large surface area available for adsorption of fuel
vapors and/or chemical reactions. During certain engine operational modes, with the
help of specifically designed control valves, the fuel vapors are adsorbed within the
canister. Subsequently, during other engine operational modes, and with the help of
additional control valves, fresh air is drawn through the canister, pulling the fuel vapor
into the engine where it is burned.

SUMMARY OF THE INVENTION
[005] An embodiment of the invention is a valve assembly for controlling fluid
flow between a first reservoir and a second reservoir. The valve assembly includes a
relief valve arranged inside the housing and configured to open the first fluid flow path
when a pressure inside the first reservoir is above a first predetermined pressure value.
[006] 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
[007] Figure 1 is a cross-sectional view of a valve assembly configured for
controlling fuel vapor flow between a fuel tank and a purge canister, with the valve
shown in a closed state, according to one embodiment of the invention;
[008] Figure 2 is a cross-sectional view of the valve assembly shown in Figure 1,
with a first flow path between the fuel tank and the purge canister shown in an open
state;
[009] Figure 3 is a cross-sectional view of the valve assembly shown in Figure 1,
with a second flow path between the fuel tank and the purge canister shown in an open
state;
[0010] Figure 4 is a cross-sectional view of the valve assembly shown in Figure 1,
with a third flow path between the fuel tank and the purge canister shown in an open
state when the fuel tank is under pressure; and
[0011] Figure 5 is across-sectional view of the valve assembly shown in Figure 1,
with a third flow path between the fuel tank and the purge canister shown in an open
state when the fuel tank is under vacuum.
DETAILED DESCRIPTION OF THE INVENTION

[0012] Referring to the drawings wherein like reference numbers correspond to like
or similar components throughout the several figures, Figure 1 illustrates a vehicle,
schematically represented by numeral 10. Vehicle 10 includes a fuel tank 12 configured
as a reservoir for holding fuel to be supplied to an internal combustion engine 13 via a
fuel delivery system which typically includes a fuel pump (not shown), as understood by
those skilled in the art. Vehicle 10 also includes a controller 14 that is configured to
regulate the operation of engine 13 and its fuel delivery system. Fuel tank 12 is
operatively connected to an evaporative emissions control system 16 that includes a
purge canister 18 adapted to collect fuel vapor emitted by the fuel tank 12 and to
subsequently release the fuel vapor to engine 13. Controller 14 is also configured to
regulate the operation of evaporative emissions control system 16 in order to recapture
and recycle the emitted fuel vapor. In addition, controller 14 is adapted to regulate the
operation of valve assembly 20, i.e., to selectively open and close the valve, in order to
provide over-pressure and vacuum relief for the fuel tank 12
[0013] Evaporative emissions control system 16 includes a valve assembly 20. Valve
assembly 20 is configured to control a flow of fuel vapor between the fuel tank 12 and
the purge canister 18. Although valve assembly 20 as shown is located between fuel
tank 12 and purge canister 18, nothing precludes locating the valve assembly in a
different position, such as between the purge canister 18 and the engine 13. Valve
assembly 20 includes a housing 22, which retains all internal components of the valve
assembly in a compact manner. Housing 22 connects to fuel tank 12 via a connector
24, and to the purge canister via a connector 26. Housing 22 accommodates a relief
valve 28. Relief valve 28 includes a piston 30, which may be formed from a suitable
chemically-resistant material such as an appropriate plastic or aluminum. Relief valve
28 may also include a compliant seal 32, which may be formed from a suitable
chemically-resistant elastomeric material. Seal 32 may be an inward-sloped dynamic
pressure seal, i.e., such that the seal's outer edge or lip is angled toward a central axis
Y1. In operation, seal 32 makes initial contact with the housing 22 along the seal's
angled outer edge. After the initial contact with housing 22, the outer edge of seal 32
deflects to conform to the housing and hermetically closes a passage 34. The inward

slope of the seal's outer edge provides enhanced control of fuel vapor flow at small
openings between seal 32 and housing 22.
[0014] Piston 30 and seal 32 may be combined into a unitary piston assembly via an
appropriate manufacturing process such as overmolding, as understood by those skilled
in the art. Piston 30 and seal 32 are urged to close passage 34 by a spring 36. As
shown in Figure 2, relief valve 28 is configured to facilitate opening a first fuel vapor
flow path being traversed by the fuel vapor flowing in a direction from the fuel tank 12
toward the purge canister 18, represented by an arrow 38, when the fuel tank 12 is
above a first predetermined pressure value. The first predetermined pressure value is
preferably a positive number, representing an extreme or over-pressure condition of
fuel tank 12.
[0015] The over-pressure condition of fuel tank 12 may depend on design
parameters typically specified according to appropriate engineering standards and
commonly includes a factor of safety to preclude operational failure of the fuel tank.
Pressure in the fuel tank 12 may vary in response to a number of factors, such as the
amount and temperature of the fuel contained therein. The first predetermined pressure
value may be established based on the design parameters of the fuel tank 12 and of the
engine's f uel delivery system, as well as based on empirical data acquired during testing
and development.
[0016] Valve assembly 20 also includes a solenoid assembly 40 arranged inside
housing 22, and adapted to receive electrical power from a vehicle alternator or from
an energy-storage device (not shown), and be triggered or energized by a control signal
from controller 14. Solenoid assembly 40 includes an armature 42, a solenoid spring
44, and a coil 46, as understood by those skilled in the art. Solenoid spring 44 is
configured to generate a force sufficient to urge armature 42 out of the solenoid
assembly 40, when the solenoid assembly is not energized. Coil 46 is configured to
energize solenoid assembly 40, and to withdraw armature 42 into the solenoid assembly
by overcoming the biasing force of spring 44.
[0017] Valve assembly 20 additionally may include a flow restrictor 50. Flow
restrictor 50 is arranged inside the housing 22, and includes a piston 52 which may be

formed from a suitable chemically-resistant material such as an appropriate plastic or
aluminum. Flow restrictor 50 also includes a compliant seal 54, which may be formed
from a suitable chemically-resistant rubber. Seal 54 is an inward-sloped dynamic
pressure seal, i.e., such that the seal's outer edge or Up is angled toward a central axis
Y2. In operation, seal 54 makes initial contact with the housing 22 along the seal's
angled outer edge. After the initial contact with housing 22, the outer edge of seal 54
deflects to conform to the housing and to hermetically close a passage 56. The inward
slope of the seal's outer edge provides enhanced control of fuel vapor flow at small
openings between seal 54 and housing 22.
[0018] Similar to the piston 30 and seal 32 above, piston 52 and seal 54 may be
combined into a unitary piston assembly via an appropriate manufacturing process such
as overmolding. Piston 52 and seal 54 are urged to close passage 56 by the action of a
spring 58. In the embodiment shown in Figure 1, flow restrictor 50 is configured to be
normally closed via the extension of armature 42 under the urging of solenoid spring 44
in the absence of the control signal from controller 14. Referring back to Figure 2, the
normally closed position of the flow restrictor, combined with the opening of relief
valve 28 (as described above), also facilitates the opening of the first flow fuel vapor
flow path represented by arrow 38.
[0019] As shown in Figure 3, passage 56 is exposed when armature 42 is withdrawn
into solenoid assembly 40 in response to the solenoid assembly being energized by the
control signal from controller 14. Spring 58 is compressed by the force of the flow of
fuel vapor, and the flow restrictor 50 is pushed out of the way by the vapor flow to
thereby facilitate the opening of passage 56. Exposing passage 56 opens a second fuel
vapor flow path to be traversed by the fuel vapor flowing in the direction from the fuel
tank 12 toward the purge canister 18, represented by arrow 60. Fuel vapor flows in the
direction represented by arrow 60 when a rate of fluid flow from fuel tank 12 to purge
canister 18 is greater than a predetermined reference value in order to open passage 56.
[0020] The rate of fluid flow from fuel tank 12 may vary in response to a number
of factors, such as the amount, temperature and pressure of the fuel contained therein.
The predetermined reference value of the rate of fluid flow may be set at, for example,

approximately 260 liters per minute (LPM), but may also be established in relation to a
higher or a lower predetermined reference value. The reference value is typically
predetermined or established in accordance with operating parameters of a particular
engine's f uel delivery system, as understood by those skilled in the art. The
predetermined rate of fluid flow, however, must be sufficiendy high to compress spring
58 and thereby expose passage 56, and the rate of spring 58 should therefore be
selected accordingly.
[0021] Piston 52 and seal 54 are urged to close passage 56 by a spring 58. Relief
valve 28 is configured to open a third fuel vapor flow path represented by arrow 62A,
as shown in Figure 4, and arrow 62B, as shown in Figure 5. Arrow 62A represents the
third fuel vapor flow path being traversed by the fuel vapor flowing in the direction
from the fuel tank 12 toward the purge canister 18, and arrow 62B represents the third
fuel vapor flow path being traversed by the fuel vapor flowing in a direction from the
purge canister 18 toward the fuel tank 12. Fuel vapor flows in the direction
represented by arrow 62B when the rate of the fluid flow from fuel tank 12 to purge
canister 18 is below the first predetermined reference value.
[0022] As shown in Figure 4, passage 64 is exposed when armature 42 is withdrawn
into solenoid assembly 40 in response to the solenoid assembly being energized by the
control signal from controller 14. The force of the flow of fuel vapor in the third fuel
vapor flow path 62A is insufficient to compress spring 58. Spring 58 is thus permitted to
extend and urge the flow restrictor 50 to close passage 56 while at the same time
exposing passage 64. In this example, the third fuel vapor flow path represented by
arrow 62A is opened when the rate of fluid flow is lower than the predetermined
reference value of approximately 260 LPM, but may also be established in relation to a
higher or a lower reference value. However, to expose passage 64, the rate of fluid
flow in the third fuel vapor flow path should be incapable of compressing spring 58;
therefore, the rate of spring 58 should be selected accordingly.
[0023] As noted above, relief valve 28 is additionally configured to open the third
fuel vapor flow path being traversed by the fuel vapor flowing in the direction
represented by arrow 62B when the fuel tank 12 is below a second predetermined

pressure value (shown in Figure 5). The first predetermined pressure value is greater
than the second predetermined pressure value. While the first predetermined pressure
value is preferably a positive number, representing an extreme or over-pressure
condition of fuel tank 12, the second predetermined pressure value is preferably a
negative number i.e., signifying that the fuel tank 12 is under a vacuum. This vacuum
in the fuel tank 12 is sufficient to overcome the force of spring 44, and thereby expose
passage 64 to open the third fuel vapor flow path. Spring 44 is specifically designed to
permit opening of the third fuel vapor flow path at a specific vacuum set point of the
fuel tank 12. As such, the rate of solenoid spring 44 generates a force that is sufficient
to close passage 64 when the fuel tank 12 is at positive pressure, but is insufficient to
close the same passage when the fuel tank is under vacuum.
[0024] In the embodiments shown in Figures 1 through 5, valve assembly 20 also
includes a cover 66, which in this example is configured as a single-piece component.
Cover 66 locates relative to the housing 22 with the aid of a flange 22A nesting inside a
channel 66A. Cover 66 engages and interconnects with housing 22 via tabbed extensions
68 that are configured to provide a snap-fit against the housing. Valve assembly 20
additionally includes a static seal 70 adapted to hermetically seal cover 66 against
housing 22. As shown in Figures 1-5, and as understood by those skilled in the art, seal
70 is of an O-ring type.
[0025] 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 valve assembly 20 configured for controlling fluid flow between a first
reservoir 12 and a second reservoir 18, the valve assembly 20 comprising:
a relief valve 28 configured to open a first fluid flow path 38 when a pressure
inside the first reservoir 12 is above a first predetermined pressure value.
2. The valve assembly 20 according to claim 1, further comprising a solenoid
assembly 40 configured to open a second fluid flow path 60 when a rate of the fluid flow
from the first reservoir 12 to the second reservoir 18 is above a predetermined reference
value.
3. The valve assembly 20 according to claim 2, further comprising a flow
restrictor 50 configured to open a third fluid flow path 62 when the rate of the fluid flow
from the first reservoir 12 to the second reservoir 18 is below the predetermined reference
value, and when the pressure inside the first reservoir 12 is below a second predetermined
pressure value
4. The valve assembly 20 according to claim 3, further comprising a housing
22 including the first 38, second 60, and third 62 fluid flow paths, wherein the relief
valve 28, the solenoid assembly 40, and the flow restrictor 50 are arranged inside the
housing 22.
5. The valve assembly 20 according to claim 3, wherein the first
predetermined pressure value is greater than the second predetermined pressure value.
6. The valve assembly 20 according to claim 3, wherein the solenoid
assembly 40 includes an armature 42 configured to selectively open and close the flow
restrictor 50, a solenoid spring 44 configured to generate a force sufficient to close the
restrictor 50 by displacing the armature 42, and a coil 46 configured to energize the
armature 42, overcome the solenoid spring 44, and thereby open the restrictor 50.

7. The valve assembly 20 according to claim 6, wherein the coil 46 is
configured to overcome the solenoid spring 44 when the rate of the fluid flow is below
the predetermined reference value.
8. The valve assembly 20 according to claim 6, wherein the solenoid spring
44 is configured to generate a force sufficient to close the third fluid flow path 62 when
the pressure inside the first reservoir 12 is a positive value, but insufficient to close the
third fluid flow path 62 when the pressure inside the first reservoir 12 is a negative value.
9. The valve assembly 20 according to claim 3, further comprising a spring
58 configured to urge the flow restrictor 50 to open, wherein the flow restrictor 50 is
configured to be normally closed.
10. The valve assembly according to claim 3, wherein at least one of the relief
valve 28 and the flow restrictor 50 includes an inward-sloped pressure seal 54 configured
to seal the corresponding relief valve 28 and the flow restrictor 50 against the housing 22.
11. The valve assembly 20 according to claim 3, further comprising a cover
66 configured to retain the relief valve 28, the flow restrictor 50, and the solenoid
assembly 40 inside the housing 22.
12. The valve assembly 20 according to claim 11, wherein the cover 66
engages and interconnects with the housing 22 via a snap-fit
13. The valve assembly 20 according to claim 11, further comprising a static
seal 70 configured to seal the cover 66 against the housing 22.
14. The valve assembly according to claim 13, wherein the static seal 70 is an
O-ring type seal.
15. A valve assembly 20 configured for controlling fluid flow between a first
reservoir 12 and a second reservoir 18, the valve assembly 20comprising:

a relief valve 28 configured to open a first fluid flow path 38 when the pressure
inside the first reservoir 12 is above a first predetermined pressure value;
a solenoid assembly 40 configured to open a second fluid flow path 60 when a
rate of the fluid flow from the first reservoir 12 to the second reservoir 18 is above a
predetermined reference value; and
a flow restrictor 50 configured to open a third fluid flow path 62 when the rate of
the fluid flow from the first reservoir 12 to the second reservoir 18 is below the
predetermined reference value, and when the pressure inside the first reservoir 12 is
below a second predetermined pressure value, wherein the first predetermined pressure
value is greater than the second predetermined pressure value.
16. The valve assembly 20 according to claim 15, further comprising:
a housing 22 including the first 38, second 60, and third 62 fluid flow paths,
wherein the relief valve 28, the solenoid assembly 40, and the flow restrictor 50 are
arranged inside the housing 22; and
a cover configured to retain the relief valve, the flow restrictor, and the solenoid
assembly inside the housing.
17. The valve assembly 20 according to claim 15, wherein the solenoid
assembly 40 includes an armature 42 configured to selectively open and close the flow
restrictor 50, a solenoid spring 44 configured to generate a force sufficient to close the
restrictor 50 by displacing the armature 42, and a coil 46 configured to energize the
armature 42, overcome the solenoid spring 44, and thereby open the restrictor 50.
18. The valve assembly according to claim 17, wherein the coil 46 is
configured to overcome the solenoid spring 44 when the rate of the fluid flow is below
the predetermined reference value, and the solenoid spring 44 is configured to generate a
force sufficient to close the third fluid flow path 62 when the first reservoir 12 is at
- positive pressure, but insufficient to close the third fluid flow path 62 when the first
reservoir 12 is at negative pressure.

19. The valve assembly 20 according to claim 15, further comprising a spring
58 configured to urge the flow restrictor 50 to open, wherein the flow restrictor 50 is
configured to be normally closed.
20. The valve assembly 20 according to claim 15, wherein at least one of the
relief valve 28 and the flow restrictor 50 includes an inward-sloped pressure seal 54
configured to seal the corresponding relief valve 28 and the flow restrictor 50 against the
housing 22.

A valve assembly 20 is disclosed for controlling fluid flow between two
reservoirs 12 and 18. The valve assembly 20 includes a relief valve 28 arranged inside
the housing 22 and configured to open a first fluid flow path 38 when the first reservoir
12 is above a first predetermined pressure value.