U.S. patent application number 16/139686 was filed with the patent office on 2019-01-24 for ecology fuel return systems.
The applicant listed for this patent is Hamilton Sundstrand Corporation. Invention is credited to Richard J. Carpenter, Ethan Flow, Kevin Gibbons, Charles E. Reuter, Lubomir A. Ribarov, Leo J. Veilleux, JR..
Application Number | 20190024588 16/139686 |
Document ID | / |
Family ID | 53886818 |
Filed Date | 2019-01-24 |
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United States Patent
Application |
20190024588 |
Kind Code |
A1 |
Carpenter; Richard J. ; et
al. |
January 24, 2019 |
ECOLOGY FUEL RETURN SYSTEMS
Abstract
A shut-off valve includes a float and a negative G control
component. The float is configured to occlude a tank outlet at a
first fluid level and 1 G and unocclude the tank outlet at a second
fluid level and 1 G. The negative G control component is
operatively connected to the float to limit fluid, e.g. liquid or
gas, communication between a tank outlet and an ejector pump during
negative G events. An ecology fuel return system includes a tank,
an ejector pump, a float, and a negative G control component, as
described above. The tank has an inlet and an outlet. The inlet is
configured to be in fluid communication with components of an
engine. The ejector pump is in fluid communication with the tank
outlet and is configured to pump fuel from the tank to a fuel pump
inlet of an engine.
Inventors: |
Carpenter; Richard J.;
(Gales Ferry, CT) ; Gibbons; Kevin; (Torrington,
CT) ; Reuter; Charles E.; (Granby, CT) ;
Ribarov; Lubomir A.; (West Hartford, CT) ; Veilleux,
JR.; Leo J.; (Wethersfield, CT) ; Flow; Ethan;
(Windsor, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hamilton Sundstrand Corporation |
Charlotte |
NC |
US |
|
|
Family ID: |
53886818 |
Appl. No.: |
16/139686 |
Filed: |
September 24, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15460681 |
Mar 16, 2017 |
10082084 |
|
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16139686 |
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|
14340275 |
Jul 24, 2014 |
9624835 |
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15460681 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y10T 137/7436 20150401;
F05D 2260/601 20130101; F02C 9/263 20130101; Y10T 137/0826
20150401; F16K 31/22 20130101; Y10T 137/7442 20150401; F05D
2300/507 20130101; F05D 2220/323 20130101; F02C 7/232 20130101;
Y10T 137/0898 20150401; F01D 17/141 20130101; F02C 9/26 20130101;
Y10T 137/7323 20150401; F01D 17/145 20130101 |
International
Class: |
F02C 7/232 20060101
F02C007/232; F02C 9/26 20060101 F02C009/26; F01D 17/14 20060101
F01D017/14 |
Claims
1. A shut-off valve comprising: a float configured to occlude a
tank outlet at a first fluid level and 1 G and unocclude the tank
outlet at a second fluid level and 1 G; and a negative G control
component operatively connected to the float to limit fluid
communication between a tank outlet and an ejector pump during
negative G events.
2. A shut-off valve as recited in claim 1, wherein the negative G
control component includes a slosh plate disposed proximate to the
float surrounding at least a portion of the float, wherein the
slosh plate is configured to concentrate fluid between the slosh
plate and the float during a negative G event to damp a
displacement of the float against a negative G event force.
3. A shut-off valve as recited in claim 2, wherein a surface area
of the slosh plate between a top of the float and the slosh plate
is smaller than a collection area of the slosh plate.
4. An ecology fuel return system, comprising: a tank having an
inlet and an outlet, wherein the inlet is configured to be in fluid
communication with components of an engine for recovery of fuel; an
ejector pump in fluid communication with the outlet of the tank,
wherein the ejector pump is configured to pump fuel from the tank
to a fuel pump inlet of an engine; a float configured to occlude a
tank outlet at a first fluid level and 1 G and unocclude the tank
outlet at a second fluid level and 1 G; and a negative G control
component operatively connected to the float to limit fluid
communication between the tank inlet and the ejector pump during
negative G events.
5. An ecology fuel return system as recited in claim 4, wherein the
negative G control component includes a slosh plate operatively
connected to the tank between the inlet and the float, wherein the
slosh plate is configured to concentrate fluid between the slosh
plate and the float during a negative G event to damp a
displacement of the float against a negative G event force.
6. An ecology fuel return system as recited in claim 5, wherein a
surface area of the slosh plate between a top of the float and the
slosh plate is smaller than a collection area of the slosh plate at
a bottom of the tank.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/460,681, filed Mar. 16, 2017, which is a
divisional application of U.S. patent application Ser. No.
14/340,275, filed Jul. 24, 2014. The contents of both of the
above-referenced applications are incorporated by reference herein
in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to fuel return systems, and,
in particular, to valves in fuel return systems.
2. Description of Related Art
[0003] Traditional ecology fuel return systems can be found in gas
turbine engines, for example, in gas turbine engines used in
aircraft. A traditional ecology fuel return system is generally
configured to remove a certain known amount of jet fuel from the
engine's fuel manifolds, for example, fuel nozzle/injector
manifolds, engine fuel supply lines, and the like, upon engine
shutdown. Upon engine startup, the jet fuel from the ecology fuel
return system is returned to the engine's fuel pump inlet via an
ejector pump to be injected in the combustor thus providing stable
engine idle operations. Ecology fuel return systems can minimize
the amount of fuel left over in the engine's fuel system after
engine shutdown, thus minimizing the possibility for any liquid
fuel and/or any gaseous fuel vapor leaks into the environment. In
addition, ecology fuel return systems can also prevent any
potential coking of the fuel manifold nozzles and injectors by
scavenging the "left-over" liquid fuel from the system upon engine
shut-down. Finally, ecology fuel return systems can drain the
combustor of any unused fuel upon engine shut-down thus preventing
any smoke exhaust from the engine upon engine start-up and
potentially causing some localized undesirable fuel-rich conditions
in the combustor (i.e., "hot spots").
[0004] Traditional ecology fuel return systems can sometimes
experience instability. For example, there is a potential for air
leakage into the aircraft's fuel system under some circumstances,
such as negative G events that can occur during some flight
maneuvers. The air entrained in the fuel could interfere with
normal operation of the engines.
[0005] Such conventional methods and systems have generally been
considered satisfactory for their intended purposes. However, there
is still a need in the art for systems and methods that allow for
improved ecology fuel return systems. The present invention
provides a solution for these problems.
SUMMARY OF THE INVENTION
[0006] A shut-off valve includes a float and a negative G control
component. The float is configured to occlude a tank outlet at a
first fluid level and 1 G and unocclude the tank outlet at a second
fluid level and 1 G. The negative G control component is
operatively connected to the float to limit fluid communication
between a tank outlet and an ejector pump during negative G
events.
[0007] The negative G control component can include a biasing
component. The biasing component can be configured to apply a
biasing force to the float. The biasing force can be greater than a
pre-determined negative G event force and less than the buoyancy
force of the float at 1 G. In an occluded position the biasing
force of the biasing component can be greater or equal to the
buoyancy force of the float at 1 G. In an unoccluded position the
biasing force of the biasing component can be less than the
buoyancy force of the float at 1 G.
[0008] The biasing component can include a spring operatively
connected to a top portion of the float. The biasing component can
include a spring retaining feature operatively connected to the
spring opposing the float. It is also contemplated that the biasing
component can include a magnet and a corresponding target, wherein
one of the magnet and the target can be fixedly connected to the
float. One of the magnet and the target can be fixedly connected to
a magnet retaining feature.
[0009] The biasing component can include a counterweighted lever,
wherein the counterweighted lever includes a lever arm and an
opposing ballast with a pivot point therebetween. The
counterweighted lever can include a spring operatively connected to
the lever arm for loading the lever arm against a top portion of
the float.
[0010] In embodiments, the negative G control component includes a
slosh plate disposed proximate to the float surrounding at least a
portion of the float. The slosh plate can be configured to
concentrate fluid between the slosh plate and the float during a
negative G event to damp the displacement of the float against a
negative G event force.
[0011] In another aspect, the negative G control component can
include a check valve in fluid communication with the float. The
check valve can be configured to block fluid flow from a tank
outlet to an ejector pump during negative G events. The check valve
can include a poppet configured to translate between a first and a
second position along a valve axis. In the first position, at 1 G
or greater, the poppet can be in an unoccluded position. In the
second position, the mass force of the poppet can be less than a
pre-determined negative G event force such that the poppet is in an
occluded position to block fluid flow to the ejector pump.
[0012] An ecology fuel return system includes a tank, an ejector
pump, a float, and a negative G control component, as described
above. The tank has an inlet and an outlet, wherein the inlet is
configured to be in fluid communication with components of an
engine for recovery of fuel. The ejector pump is in fluid
communication with the outlet of the tank and is configured to pump
fuel from the tank to a fuel pump inlet of an engine.
[0013] In embodiments including the slosh plate, as described
above, the slosh plate can be connected to the tank between the
inlet and the float. It is contemplated that the ecology fuel
return system can include a boost pump in fluid communication with
the ejector pump. The boost pump can be configured to induce fuel
flow through the ejector pump from a fuel pump inlet of an
engine.
[0014] These and other features of the systems and methods of the
subject invention will become more readily apparent to those
skilled in the art from the following detailed description of the
preferred embodiments taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] So that those skilled in the art to which the subject
invention appertains will readily understand how to make and use
the devices and methods of the subject invention without undue
experimentation, preferred embodiments thereof will be described in
detail herein below with reference to certain figures, wherein:
[0016] FIG. 1A is a schematic cross-sectional view of an exemplary
embodiment of an ecology fuel return system constructed in
accordance with the present disclosure, showing the biasing
component as a spring and the float in an occluded position under
positive G forces;
[0017] FIG. 1B is a schematic cross-sectional view of the ecology
fuel return system of FIG. 1A, showing the float in an unoccluded
position under positive G forces;
[0018] FIG. 1C is a schematic cross-sectional view of the ecology
fuel return system of FIG. 1A, showing the float in an occluded
position under negative G forces;
[0019] FIG. 2 is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
tank with a sloped bottom;
[0020] FIG. 3A is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
biasing component as a magnet and a target, and the float in an
occluded position under positive G forces;
[0021] FIG. 3B is a schematic cross-sectional view of the ecology
fuel return system of FIG. 3A, showing the float in an unoccluded
position under positive G forces;
[0022] FIG. 3C is a schematic cross-sectional view of the ecology
fuel return system of FIG. 3A, showing the float in an occluded
position under negative G forces;
[0023] FIG. 4A is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
biasing component as a counterweighted lever and the float in an
occluded position under positive G forces;
[0024] FIG. 4B is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the float in an unoccluded
position under positive G forces;
[0025] FIG. 4C is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the float in an occluded
position under negative G forces;
[0026] FIG. 5 is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
biasing component as a counterweighted lever with a slotted pivot
connecting the lever to the float;
[0027] FIG. 6A is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
slosh plate and the float, where the float is in an occluded
position under positive G forces;
[0028] FIG. 6B is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the float in an unoccluded
position under positive G forces;
[0029] FIG. 6C is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the float in an occluded
position under negative G forces;
[0030] FIG. 7A is a schematic cross-sectional view of a portion of
another exemplary embodiment of an ecology fuel return system
constructed in accordance with the present disclosure, showing the
check valve and the poppet in an unoccluded position and the float
in an occluded position under positive G forces;
[0031] FIG. 7B is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the check valve and the
poppet in an unoccluded position and the float in an unoccluded
position under positive G forces; and
[0032] FIG. 7C is a schematic cross-sectional view of the ecology
fuel return system of FIG. 4A, showing the check valve and the
poppet in an occluded position and the float in an unoccluded
position under negative G forces.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Reference will now be made to the drawings wherein like
reference numerals identify similar structural features or aspects
of the subject disclosure. For purposes of explanation and
illustration, and not limitation, a perspective view of an
exemplary embodiment of an ecology fuel return system in accordance
with the disclosure is shown in FIG. 1A and is designated generally
by reference character 100. Other embodiments of ecology fuel
return systems in accordance with the disclosure, or aspects
thereof, are provided in FIGS. 1B-7C, as will be described. The
systems and methods of the invention can be used to reduce the
entrainment of continuous airflow into the fuel system, for example
during negative G loading events, such as during aircraft maneuvers
and turbulence, where the tank is driven to accelerate against
gravity.
[0034] As shown in FIG. 1A, an ecology fuel return system 100
includes a tank 102, an ejector pump 104, a boost pump 110, and a
shut-off valve 105 with a float 106 and a negative G control
component 108. Tank 102 has an inlet 112, an outlet 114 and a vent
103. Vent 103 prevents pressurization of and a vacuum in tank 102.
A vacuum in tank 102 can prevent fluid flow, e.g. liquid and/or gas
flow, when valve 105 opens. Inlet 112 is configured to be in fluid
communication with components of an engine (not shown) for recovery
of fuel. Ejector pump 104 is in fluid communication with outlet 114
of tank 102 and is configured to pump fuel from tank 102 to a fuel
pump inlet of the engine (not shown). Boost pump 110 is in fluid
communication with ejector pump 104. Boost pump 110 is configured
to induce fuel flow through ejector pump 104 from the fuel pump
inlet of the engine.
[0035] With reference to FIGS. 1A-C, float 106 is configured to
occlude tank outlet 114 at a first fluid level and 1 G, shown in
FIG. 1A, and unocclude tank outlet 114 at a second fluid level and
1 G, shown in FIG. 1B. FIGS. 1A and 1B are examples of float 106
positions during positive G scenarios. Negative G control component
108 is operatively connected to float 106 to limit fluid
communication between tank inlet 112 and/or vent 103, and ejector
pump 104 during negative G events, for example the negative G event
shown in FIG. 1C.
[0036] With continued reference to FIGS. 1A-1C, negative G control
component 108 includes a biasing component 116 shown as a spring.
Biasing component 116, e.g. spring, also includes a spring
retaining feature 120 operatively connected to spring 116 opposing
float 106. Spring 116 is configured to apply a biasing force
F.sub.bias to float 106. Spring 116 is operatively connected to a
top portion 118 of float 106 and to spring retaining feature 120.
The direction of biasing force F.sub.bias is indicated
schematically by a downward pointing arrow in FIGS. 1A-1C.
[0037] As shown in FIG. 1A, biasing force F.sub.bias of spring 116
is greater or equal to a buoyancy force F.sub.B of float 106 at a
first fluid level and 1 G. The direction of buoyancy force F.sub.B
of float 106 is indicated schematically by an upward pointing arrow
on the right-hand side, as oriented in FIGS. 1A-1C. The direction
of the G force, F.sub.G, is indicated schematically by a downward
pointing arrow on the left-hand side as oriented in FIG. 1A. Those
skilled in the art will readily appreciate that proper sizing of
this design results in sizing float 106 so that as the fluid level
in tank 102 increases, its buoyancy force F.sub.B can overcome
biasing force F.sub.bias of spring 116.
[0038] With reference now to FIG. 1B, as the fluid level in tank
102 increases, biasing force F.sub.bias of spring 116 becomes less
than buoyancy force F.sub.B of float 106 at 1 G. The direction of G
force F.sub.G is indicated schematically by a downward pointing
arrow on the left-hand side, as oriented in FIG. 1B. As float 106
rises, it further compresses spring 116 and moves to an unoccluded
position. This increases the force limiting the movement of float
106, and, therefore also limits the resulting float 106
displacement. In the unoccluded position, float 106 does not block
fluid communication through shut-off valve 105 to ejector pump 104.
Fluid travels from tank inlet 112, through shut-off valve 105, as
indicated by the two inward pointing arrows, to tank outlet 114,
and to ejector pump 104.
[0039] Referring now to FIG. 1C, ecology fuel return system 100 is
shown in a negative G event. The negative G event causes a negative
G force F.sub.-G. The direction of negative G force F.sub.-G is
indicated schematically by an upward pointing arrow on the
left-hand side, as oriented in FIG. 1C. This negative G force, in
traditional ecology fuel return systems, with the aircraft in its
normal flight attitude, tends to cause fluid in a tank and a float
to move upwards, allowing air to flow from the tank to be drawn
into a pump and into a corresponding engine. In ecology fuel return
system 100, biasing force F.sub.bias of spring 116 is greater than
negative G event force F.sub.-G so that when buoyancy force F.sub.B
of float 106 decreases due to the fluid moving out from under float
106, biasing force F.sub.bias of spring 116 overcomes negative G
event force F.sub.-G and forces float 106 to an occluded position
covering tank outlet 114 and reducing the air ingestion via ejector
pump 104. Ecology fuel return system 100 allows the fluid level to
be above shut-off valve opening 124, such that float 106 will be
partially submerged leaving more residual fluid in tank 102 at
shut-off. Those skilled in the art will readily appreciate that a
small amount of fuel remaining in tank 102 after engine shut-off
tends to ensure minimal air entrapment in the fuel supply lines
upon engine re-start, helping to avoid any discontinuous fuel
supply to the engine's fuel injectors. It is contemplated that in
some applications residual fluid in tank 102 can be reduced by
sloping the bottom of tank 102 towards shut-off valve opening 124
and outlet 114, as described below with respect to FIG. 2.
[0040] As shown in FIG. 2, ecology fuel return system 100 is shown
with a shut-off valve opening 124 closer to a bottom 123 of tank
102. Bottom 123 of tank 102 also includes a slope 122 towards
shut-off valve opening 124 and outlet 114. Sloped tank bottom 123
limits the accumulated fluid volume in tank 102 at shut-off. The
angle and overall shape of slope 122 are such that the remaining
fuel volume is minimized. Those skilled in the art will readily
appreciate that by reducing the amount of fuel volume left over in
the ecology fuel tank after engine shut-off a smaller ecology fuel
tank can be used, therein reducing the overall weight of the
system, fuel spill potential and release of fuel vapors can be
reduced, therein mitigating potential environmental impact, and the
propensity for visible exhaust smoke during cold engine re-start
can be reduced. It is contemplated that there are a variety of
suitable geometric configurations for tank bottom 123 that can be
used.
[0041] Now with reference to FIGS. 3A-3C, another exemplary
embodiment of an ecology fuel return system 200 is shown. Ecology
fuel return system 200 is similar to ecology fuel return system
100, except that a negative G control component 208 of system 200
includes a biasing component 216 that is a magnet 226 and a
corresponding target 228 instead of a spring. Magnet 226 is
connected to float 206 and target 228 is connected to a magnet
retaining feature 220. Those skilled in the art will readily
appreciate that magnet 226 can alternatively be connected to magnet
retaining feature 220 and target 228 can be connected to float 206.
It is also contemplated that magnet 226 and its respective target
228 can be oriented in a variety of suitable positions and have a
variety of suitable geometric shapes, as needed for a given
application.
[0042] As shown in FIG. 3A, a biasing force F.sub.bias of biasing
component 216, e.g. a latching force F.sub.latch of magnet 226 and
target 228, is greater or equal to a buoyancy force F.sub.B of
float 206 at a first fluid level and a G force F.sub.G, e.g. 1 G,
similar to ecology fuel return system 100 shown in FIG. 1A. The
direction of G force F.sub.G is indicated schematically by a
downward pointing arrow on the left-hand side, as oriented in FIGS.
3A and 3B. The direction of latching force F.sub.latch is indicated
schematically by a downward pointing arrow in FIGS. 3A-3C. The
direction of buoyancy force F.sub.B is indicated schematically by
an upward pointing arrow on the right-hand side, as oriented in
FIGS. 3A-3C. Those skilled in the art will readily appreciate that
magnet 226, e.g. permanent magnet, and target 228, e.g.
magnetically permeable target, are brought close enough in
proximity in order to induce a magnetic attraction force, e.g.
F.sub.latch, large enough to close float 206 and/or to keep float
206 closed.
[0043] With reference now to FIG. 3B, as the fluid level in tank
202 increases, latching force F.sub.latch of magnet 226 and target
228 becomes less than buoyancy force F.sub.B of float 206 at a
second fluid level and 1 G, similar to ecology fuel return system
100 shown in FIG. 1B. As the fluid level in tank 202 rises,
buoyancy force F.sub.B of float 206 overcomes latching force
F.sub.latch of magnet 226 and target 228 and float 206 moves into
an unoccluded position, similar to unoccluded position described
above with respect to FIG. 1B. Because F.sub.latch only acts in
close proximity between magnet 226 and target 228, once latching
force F.sub.latch is overcome there is no additional load on float
206 as there is with float 106 of ecology fuel return system
100.
[0044] Referring now to FIG. 3C, a negative G event, similar to the
negative G event described above with respect to ecology fuel
return system 100, is shown. In ecology fuel return system 200,
latching force F.sub.latch of magnet 226 and target 228 is greater
than negative G event force F.sub.-G, the direction of which is
indicated schematically by an upward pointing arrow, in order to
overcome negative G event force F.sub.-G, similar to biasing force
F.sub.bias of spring 116 as described above with respect to FIG.
1C. Ecology fuel return system 200 with the magnet design also
allows the fluid level to be above opening 224 of shut-off valve
205, as described above with respect to ecology fuel return system
100. Those skilled in the art will readily appreciate that residual
fluid in tank 202 can be reduced by having the latching distance
between magnet 226 and target 228 kept to a minimum. It is also
contemplated that the residual fluid can be reduced by sloping the
bottom of tank 202 toward opening 224 and outlet 214, and/or having
opening 224 of shut-off valve 205 closer to the bottom of tank 202,
similar to tank 102 shown in FIG. 2.
[0045] As shown in FIGS. 4A-4C, another embodiment of an ecology
fuel return system 300 is shown. Ecology fuel return system 300 is
similar to ecology fuel return system 100, except that a negative G
control component 308 of system 300 includes a biasing component
316 that is a counterweighted lever. Biasing component 316, e.g.
counterweighted lever, includes a lever arm 326 and an opposing
ballast 328 with a pivot point 330 therebetween. A coil spring at
pivot point 330 operatively connects to lever arm 326 for loading
lever arm 326 against a top portion 318 of float 306.
[0046] Referring now to FIG. 4A, a biasing force F.sub.bias of
counterweighted lever 316, the direction of which is indicated
schematically by a downward pointing arrow in FIGS. 4A-4C, is
greater or equal to a buoyancy force F.sub.B of float 306, the
direction of which is indicated schematically by an upward pointing
arrow in FIGS. 4A-4C, at a first fluid level and a G force F.sub.G,
e.g. 1 G, similar to ecology fuel return system 100 shown in FIG.
1A. The direction of G force F.sub.G is indicated schematically by
a downward pointing arrow on the left-hand side, as oriented in
FIGS. 4A and 4B. At this position, counterweighted lever 316 is
nearly in force-balance about pivot point 330 with a slight bias
provided by the coil spring to keep lever arm 326 in contact with
float 306.
[0047] With reference now to FIG. 4B, as the fluid level in tank
302 increases, the biasing force F.sub.bias of counterweighted
lever 316 becomes less than buoyancy force F.sub.B of float 306 at
1 G and float 306 moves into an unoccluded position, similar to
ecology fuel return system 100 shown in FIG. 1B, described above.
Similar to ecology fuel return system 100, the spring load on the
coil spring also increases as the fluid level in tank 302
increases, but by a smaller magnitude since it is contributing only
the force required to offset the counter weight at a zero G force.
This reduced spring load reduces the buoyancy force F.sub.B
required to move float 306 to an occluded position, reducing the
size of float 306 required.
[0048] Referring now to FIG. 4C, a negative G event is shown. The
negative G event is similar to the negative G event shown and
described with respect to FIG. 1C. The direction of negative G
force F.sub.-G is indicated schematically by an upward pointing
arrow. In ecology fuel return system 300, a torque about pivot
point 330 fixed to tank 302 is generated to keep float 306 in the
closed position during the negative G event. Ecology fuel return
system 300 also allows the fluid level to be above shut-off valve
opening 324, similar to ecology fuel return system 100 described
above. It is contemplated that residual fluid left in tank 302 can
be reduced by sloping the bottom of tank 302 toward shut-off valve
opening 324 and outlet 314, and/or having shut-off valve opening
324 closer to the bottom of tank 302, similar to tank 102 shown in
FIG. 2.
[0049] As shown in FIG. 5, counterweighted lever 316 includes a
slotted pivot 334 instead of the coil spring to operatively connect
lever arm 326 and float 306. Those skilled in the art will readily
appreciate that slotted pivot 334 may tend to cause counterweighted
lever 316 to be susceptible to positive G events that drive float
306 to close when it may need to be open to drain tank 302. For
example, additional lateral displacement of tank 302 may cause
internal fluid displacement that could cause float 306 to rise,
potentially ingesting air even when under positive G forces. Those
skilled in the art will readily appreciate that internal baffles
(not shown) may be used to limit such displacement. System 300 with
slotted pivot 334 also decreases the number of degrees of freedom
(DOF) by one (in the z-direction, i.e., in/out of the page as
oriented in FIG. 5). Movements in the horizontal (x-direction) and
vertical (y-direction), indicated schematically by the axis arrows
on the left-hand side as oriented in FIG. 5, are allowed. System
300 with coil spring , shown in FIGS. 4A-4C, allows 3 DOF in the
x-, y-, and z-directions.
[0050] As shown in FIGS. 6A-C, another embodiment of an ecology
fuel return system 400 is shown. Ecology fuel return system 400 is
similar to ecology fuel return system 100, except that negative G
control component 408 does not include a biasing component, e.g.
spring 116, as shown and described above with respect to FIGS.
1A-1C. Instead, negative G control component 408 includes a slosh
plate 416 disposed proximate to float 406 surrounding at least a
portion of float 406. Slosh plate 416 is connected to tank 402
between an inlet, not shown, but similar to inlet 112, and float
406. Those skilled in the art will readily appreciate that ecology
fuel return system 400 has no moving parts except for float 406,
therefore advantageously reducing the possible failure modes.
[0051] Referring now to FIG. 6A, float 406 is in a similar position
as described above with respect to FIG. 1A. Float 406, however,
does not include a biasing component. Therefore, a buoyancy force
F.sub.B of float 406 does not have to overcome any additional force
in order to provide fluid flow to the ejector pump, not shown, at a
G force F.sub.G, e.g. 1 G. The direction of G force F.sub.G is
indicated schematically by a downward pointing arrow on the
left-hand side, as oriented in FIGS. 6A and 6B. Ecology fuel return
system 400 also allows the fluid level to be above an opening 424
of shut-off valve 405, similar to ecology fuel return system 100
described above. It is contemplated that residual fluid left in
tank 402 can be reduced by sloping the bottom of tank 402 towards
shut-off valve opening 424 and outlet 414, and/or having shut-off
valve opening 424 closer to the bottom of tank 402, similar to tank
102 shown in FIG. 2.
[0052] As shown in FIG. 6B, as the fluid level in tank 402
increases, buoyancy force F.sub.B of float 406 at 1 G increases and
float 406 moves into an unoccluded position above opening 424 of
shut-off valve 405, similar to ecology fuel return system 100 shown
in FIG. 1B, described above. The direction of buoyancy force
F.sub.B is indicated schematically by an upward pointing in FIGS.
6A-6B. It is contemplated that a top of float 418 may contact slosh
plate 416, but that top of float 418 can be shaped in a way as to
permit the fluid to flow between it and slosh plate 416. For
example, it is contemplated that, the top of float 418 may have any
continuous smooth geometrical shape that allows free contact
between the top of float 418 and slosh plate 416, such as
spherical, concave, convex, linear, or the like.
[0053] Now with reference to FIG. 6C, a negative G event is shown.
The negative G event is similar to the negative G event shown and
described with respect to FIG. 1C. Slosh plate 416 is configured to
concentrate fluid between slosh plate 416 and float 406 during the
negative G event to damp the displacement of float 406 against a
negative G event force F.sub.-G. The direction of negative G force
F.sub.-G is indicated schematically by an upward pointing arrow on
the left-hand side, as oriented in FIG. 6C. The surface area of
slosh plate 416 where top of float 418 and slosh plate 416 meet is
smaller than the collection area of slosh plate 416 near the bottom
of tank 402. During a negative G event, this difference assists in
concentrating the fluid volume as it displaces into slosh plate
416. The volume of fluid concentrated under slosh plate 416 and the
resulting momentum of that fluid provides a force F.sub.fluid to
limit float 406 displacement and drive float 406 back to the
occluded position directly above opening 424 of shut-off valve 405.
The amount of fluid volume displaced and the velocity of the
displaced fluid limits the duration of force F.sub.fluid. The
direction of force F.sub.fluid is indicated schematically by a
downward pointing arrow. Those skilled in the art will readily
appreciate that float 406 and fluid may initially displace together
during the negative G event, potentially allowing a temporary
ingestion of air into fuel system 400.
[0054] As shown in FIGS. 7A-7C, another embodiment of an ecology
fuel return system 500 is shown. Ecology fuel return system 500 is
similar to ecology fuel return system 100, except that a negative G
control component 508 does not include a biasing component, e.g.
spring 116, as shown and described above with respect to FIGS.
1A-1C. Instead, negative G control component 508 is a check valve
in fluid communication with a float 506. Negative G control
component 508, e.g. check valve, includes a poppet 526 configured
to freely translate along a valve axis A. Poppet 526 is configured
to translate between a first unoccluded position, shown in FIGS. 7A
and 7B, and a second occluded position, shown in FIG. 7C. Check
valve 508 is configured to block fluid flow from a tank outlet 514
to an ejector pump 504 during negative G events. Ejector pump 504
is similar to ejector pump 104, described above. It is contemplated
that a boost pump, similar to boost pump 110, while not shown, can
be in fluid communication with ejector pump 504.
[0055] Now with reference to FIG. 7A, in a first position, at a
first fluid level and at 1 G or greater, poppet 526 is in an
unoccluded position. Float 506 is in a similar occluded position,
above and opening 524 of shut-off valve 505, as described above
with respect to FIG. 1A. Float 506, however, does not include a
biasing component, e.g. spring 116. Therefore, a buoyancy force
F.sub.B of float 506 does not have to overcome any additional force
in order to provide fluid flow to ejector pump 504 at a G force
F.sub.G, e.g. 1 G. The direction of G force F.sub.G is indicated
schematically by downward pointing arrows on the left-hand side, as
oriented in FIGS. 7A and 7B. The direction of buoyancy force
F.sub.B is indicated schematically by an upward pointing arrow on
the right-hand side, as oriented in FIGS. 7A-7B.
[0056] As shown in FIG. 7B, as the fluid level in tank 502
increases, buoyancy force F.sub.B of float 506 at 1 G or greater
increases and float 506 moves into an unoccluded position, similar
to ecology fuel return system 100 shown in FIG. 1B, described
above. Poppet 526 remains in an unoccluded position to allow fluid
to flow to ejector pump 504.
[0057] Now with reference to FIG. 7C, a negative G event is shown.
The negative G event is similar to the negative G event shown and
described with respect to FIG. 1C. The direction of a negative G
force F.sub.-G is indicated schematically by upward pointing arrows
on the left-hand side, as oriented in FIG. 7C. Float 506, however
does not have any biasing component, for example spring 116, or a
damping component, e.g. slosh plate 416, thus float 506 is
sensitive to the influence of external loads as shut-off valve 505
operates with low-to-no force margin to keep it closed. Therefore,
float 506 is forced upwards, as oriented in FIG. 7C, and remains in
an unoccluded position during a negative G event. During a negative
G event, poppet 526 is also forced upwards, as oriented in FIG. 7C,
and seats in valve inlet 528, sealing valve inlet 528 and
preventing flow from tank outlet 514 to ejector pump 504.
[0058] Those skilled in the art will readily appreciate that poppet
526 can have a variety of suitable sizes and shapes, but generally
should be large enough to allow for an adequate sealing surface,
and small enough to minimize drag effects on poppet 526 that could
prevent it from seating properly in valve inlet 528. It is
contemplated that poppet 526 can be made of a dense material, such
that poppet 526 has a sufficient momentum during a negative G event
to properly seal valve inlet 528. Those skilled in the art will
readily appreciate that by minimizing the actuation distance, e.g.
the distance poppet 526 needs to travel along valve axis A from a
full open position, shown in FIG. 7A, to full closed position,
shown in FIG. 7C, the amount of air that can be ingested by ejector
pump 504 during the closing of valve inlet 528 at the beginning of
the negative G event tends to be reduced. It is also contemplated
that a poppet guide can be designed to prevent any movement of
poppet 526 in unintended alternate directions, e.g. directions at
an angle with respect to valve axis A. Those skilled in the art
will also readily appreciate that because poppet 526 is essentially
unrestricted along valve axis A, contact surfaces of poppet 526 can
be designed to minimize or eliminate negative effects caused by
poppet vibration.
[0059] The methods and systems of the present disclosure, as
described above and shown in the drawings, provide for ecology fuel
return systems with superior properties including reduced air
ingestion into the engine's main fuel lines during negative G
events. Reduced airflow into the engine's main fuel lines, in turn,
can reduce fuel coking and plugging of fuel injectors and nozzles,
which increases the possibility that the engine will operate at
full power and efficiency, reduce fuel pump degradation, reduce the
possibility of fuel cavitation in the main fuel pump, and reduce
the possibility of in-flight shut-downs. While the apparatus and
methods of the subject disclosure have been shown and described
with reference to preferred embodiments, those skilled in the art
will readily appreciate that changes and/or modifications may be
made thereto without departing from the spirit and scope of the
subject disclosure.
* * * * *