U.S. patent application number 15/606790 was filed with the patent office on 2017-09-14 for auxilliary reservoir for a liquid system.
The applicant listed for this patent is Hamilton Sundstrand Corporation. Invention is credited to Lance R. Bartosz, George E. Wilmot, JR..
Application Number | 20170261267 15/606790 |
Document ID | / |
Family ID | 44787293 |
Filed Date | 2017-09-14 |
United States Patent
Application |
20170261267 |
Kind Code |
A1 |
Bartosz; Lance R. ; et
al. |
September 14, 2017 |
AUXILLIARY RESERVOIR FOR A LIQUID SYSTEM
Abstract
A liquid system for circulating a liquid through a circulation
loop includes a liquid pump, a primary liquid reservoir and an
auxiliary liquid reservoir. The liquid pump pressurizes liquid
within the circulation loop. The primary liquid reservoir has a
primary variable volume expandable to accommodate volumetric
expansion of pressurized liquid up to a threshold volume. The
auxiliary liquid reservoir has an auxiliary variable volume
expandable only after the threshold volume is exceeded up to a
maximum volume.
Inventors: |
Bartosz; Lance R.; (Granby,
MA) ; Wilmot, JR.; George E.; (East Granby,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hamilton Sundstrand Corporation |
Charlotte |
NC |
US |
|
|
Family ID: |
44787293 |
Appl. No.: |
15/606790 |
Filed: |
May 26, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12760723 |
Apr 15, 2010 |
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15606790 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64D 2013/0614 20130101;
B64D 2013/0674 20130101; F28D 15/043 20130101; F25D 17/02 20130101;
B64D 13/00 20130101; A47F 3/04 20130101; F28D 15/00 20130101; B64D
2013/0629 20130101 |
International
Class: |
F28D 15/04 20060101
F28D015/04; F25D 17/02 20060101 F25D017/02 |
Claims
1. A liquid system for circulating a liquid through a circulation
loop, the liquid system comprising: a liquid pump for pressurizing
liquid within the circulation loop to circulate the pressurized
liquid through the circulation loop so that the pressurized liquid
transfers heat to and from locations along the circulation loop,
the pressurized liquid within the circulation loop having a volume
that varies due to thermal expansion from an initial volume to a
threshold volume, and from the threshold volume to a maximum
volume; a primary liquid reservoir in fluid communication with the
circulation loop and having a primary variable volume expandable in
response to volumetric expansion of the pressurized liquid due to
thermal expansion up to the threshold volume; and an auxiliary
liquid reservoir in fluid communication with the circulation loop
and having an auxiliary variable volume expandable in response to
volumetric expansion of the pressurized liquid due to thermal
expansion only after the threshold volume of the pressurized liquid
is exceeded and expandable up to the maximum volume; wherein the
liquid fills the liquid system, and air is omitted from the liquid
system.
2. The liquid system of claim 1 wherein the primary variable volume
accommodates volumetric expansion of the liquid across operating
pressures of the liquid pump up to a threshold pressure.
3. The liquid system of claim 2 wherein the auxiliary variable
volume accommodates volumetric expansion of the liquid above the
threshold pressure up to a maximum pressure.
4. The liquid system of claim 3 and further comprising: a relief
valve connected to the circulation loop and configured to open
above the maximum pressure.
5. The liquid system of claim 3 wherein the auxiliary liquid
reservoir comprises a spring-charged bellows having a spring with a
spring force that yields above the threshold pressure.
6. The liquid system of claim 5 wherein the primary liquid
reservoir comprises a bootstrap reservoir.
7. The liquid system of claim 6 wherein the liquid pump and the
primary liquid reservoir are packaged in a common housing and the
auxiliary liquid reservoir is packaged in a separate housing.
8. The liquid system of claim 6 wherein the primary liquid
reservoir includes a level sensor for determining a volume of fluid
within the primary liquid reservoir.
9. The liquid system of claim 1 and further comprising: a liquid
load connected to the liquid pump through the circulation loop;
wherein the liquid load imparts a thermal input to the pressurized
liquid.
10. A liquid system comprising: a circulation loop; a liquid pump
configured to pressurize liquid within the circulation loop wherein
the liquid fills and circulates through the circulation loop to
transfer heat to and from locations along the circulation loop, and
air is omitted from the circulation loop; a primary reservoir in
fluid communication with the circulation loop and configured to
expand in volume in response to volumetric expansion of the liquid
due to thermal expansion under pressure within the circulation loop
up to a threshold pressure; and an auxiliary reservoir in fluid
communication with the circulation loop and configured to expand in
volume in response to volumetric expansion of the liquid due to
thermal expansion only after the threshold pressure is exceeded;
wherein activations of the primary reservoir and the auxiliary
reservoir in response to volumetric expansion of the liquid due to
thermal expansion are staged such that utilization of volumetric
capacity of the auxiliary reservoir occurs only after volumetric
capacity of the primary reservoir is maxed out.
11. The liquid system of claim 10 and further comprising: a liquid
load connected to the liquid pump through the circulation loop;
wherein the liquid load imparts a thermal input to the liquid.
12. The liquid system of claim 11 wherein the auxiliary reservoir
comprises a spring charged bellows having a spring with a spring
force that yields above the threshold pressure.
13. The liquid system of claim 12 wherein the primary reservoir
comprises a bootstrap reservoir integrated into a housing of the
fluid pump, and the auxiliary reservoir is packaged in a separate
housing.
14. The liquid system of claim 12 wherein the primary reservoir
includes a level sensor for determining a volume of fluid within
the primary reservoir.
15. The liquid system of claim 10 wherein the auxiliary reservoir
expands to a maximum volume after the primary reservoir expands to
a threshold volume.
16. A method of accommodating expanding liquid in a closed fluid
circulation loop, the method comprising: circulating pressurized
liquid in a closed fluid circulation loop using a pump, wherein the
liquid transfers heat to and from locations along the closed fluid
circulation loop, and wherein the pressurized liquid fills the
closed fluid circulation loop and air is omitted from the closed
fluid circulation loop; expanding a volume of a primary reservoir
connected to the closed fluid circulation loop up to a threshold
volume in response to thermal expansion of the pressurized liquid
to a threshold level; and sequentially expanding a volume of an
auxiliary reservoir connected to the closed fluid circulation loop
up to a maximum volume in response to thermal expansion of the
pressurized fluid from the threshold level to a maximum level.
17. The method of claim 16 wherein the volume of the primary
reservoir is expanded to a threshold pressure and the volume of the
auxiliary reservoir is expended after the threshold pressure is
reached.
18. The method of claim 17 wherein the step of expanding the volume
of the primary reservoir comprises expanding a bootstrap reservoir
integrated with the pump.
19. The method of claim 18 wherein the step of expanding the volume
of the auxiliary reservoir comprises expanding a bellows-type
reservoir having a spring that yields at the threshold pressure.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation of U.S. application Ser.
No. 12/760,723 filed Apr. 15, 2010 for "AUXILLIARY RESERVOIR FOR A
LIQUID SYSTEM" by Lance R. Bartosz and George E. Wilmot, Jr. The
aforementioned U.S. application Ser. No. 12/760,723 is hereby
incorporated by reference in their entirety.
BACKGROUND
[0002] The present invention relates to liquid circulation systems
and more particularly to reservoirs for liquid cooling systems used
in aircraft.
[0003] Modern aircraft include many complex systems that include
liquid circulation systems, such as environmental control systems,
galley cooling systems and electronics systems. These systems are
interconnected through a network that circulates various fluids and
gases between the systems using components such as valves, pumps
and electric motors. Some of these liquid systems generate heat
that is carried away by other fluid systems to be dumped overboard
from the aircraft. For example, the components are controlled by
power electronics that consume large amounts of electric power and
therefore generate heat that must be removed. Typical cooling
systems used in these liquid systems involve closed loops that
circulate a liquid coolant, such as a mixture of water and glycol,
through heat exchangers using pumps.
[0004] The cooling systems are subject to temperature extremes
ranging from the extreme cold of the upper atmosphere to the high
temperatures generated within the systems. The liquid coolant
therefore undergoes wide ranging temperature changes, which varies
the volume of the liquid coolant due to thermal expansion. In order
to absorb the volumetric expansion of the coolant throughout the
operating cycle of the system, liquid cooling systems are provided
with accumulators or reservoirs that provide an overflow volume.
The reservoir holds a volume of coolant when temperatures are hot
and the coolant is expanded. The reservoir returns the coolant to
circulation when the coolant cools and contracts. In order to
reduce the size of the cooling system and the space occupied in the
aircraft, the reservoir is often incorporated into a package with
the pump. For example, bootstrap reservoirs use pump inlet and
outlet pressures to adjust the reservoir volume with system
pressure changes. Furthermore, the capacity of the reservoir is
typically sized for the requirements of a particular cooling system
and aircraft platform. As such, redesign or scaling of
pump-integrated accumulators is not a cost-effective option when
designing liquid systems for new aircraft platforms.
SUMMARY
[0005] The present invention is directed to a liquid system for
circulating a liquid through a circulation loop, such as liquid
cooling loops used in aircraft. The liquid system comprises a
liquid pump, a primary liquid reservoir and an auxiliary liquid
reservoir. The liquid pump pressurizes liquid within the
circulation loop. The primary liquid reservoir has a primary
variable volume expandable to accommodate volumetric expansion of
pressurized liquid up to a threshold volume. The auxiliary liquid
reservoir has an auxiliary variable volume expandable only after
the threshold volume is exceeded up to a maximum volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows a schematic of a liquid cooling system having a
liquid load, a pump and reservoir package and an auxiliary
reservoir of the present invention.
[0007] FIG. 2 shows a diagrammatic illustration of the pump and
reservoir package and the auxiliary reservoir of FIG. 1.
DETAILED DESCRIPTION
[0008] FIG. 1 shows a schematic of liquid system 10 having pump
package 12, liquid loads 14, 16 and 18, and auxiliary reservoir 20.
Pump package 12 includes pump 22, primary reservoir 24 and valve
26. Liquid loads 14 and 16 include heat exchangers 28 and 30,
respectively, and liquid load 14 includes check valve 32 and
diverter valve 34. Liquid load 18 includes cooling circuits 36A and
36B (which include evaporators 38A and 38B and condensers 40A and
40B, respectively), pressure sensor 42 and temperature sensor 44.
Liquid loads 14, 16 and 18 and auxiliary reservoir 20 are connected
to pump package 12 with liquid lines 46A-46F.
[0009] Liquid system 10 comprises a system for circulating fluid
through a closed circulation loop. For example, system 10 may
comprise a cooling system integrated into an aircraft environmental
control system (ECS) that circulates a cooling fluid. As such,
system 10 is typically incorporated into an aircraft airframe.
Liquid loads 14, 16 and 18 represent areas or spaces within the
airframe that demand different levels and types of cooling. For
example, liquid load 18 comprises a pressurized cargo bay portion
of the airframe where aircraft electronics, such as power
electronics or avionics, are stored. Liquid loads 14 and 16
comprise unpressurized regions of the airframe such as pack bays
where ECS equipment is stowed. However, any space within an
aircraft, such as the cabin, may be connected to system 10. Liquid
system 10 provides a fluid medium that transfers heat to and from
various places within system 10.
[0010] Pump 22 of pump package 12 pressurizes a cooling fluid
within loop lines 46A-46F. The fluid flows from pump package 12 to
liquid load 18 through line 46A. Cooling circuits 36A and 36B of
liquid load 18 are in thermal communication with lines 46A and 46B
through evaporators 38A and 38B, and with lines 48A and 48B through
condensers 40A and 40B. Although two circuits are shown, additional
circuits may be added as provided by design requirements. Cooling
fluid in lines 48A and 48B is heated by circulating through hot
electronics (or heat exchangers in thermal communication with the
electronics) and cooled by circulating through cooled heat
exchangers in communication with ram air ducts (not shown).
Evaporators 38A and 38B unload heat from system 10 and condensers
40A and 40B impart the heat into lines 48A and 48B for removal from
circuits 36A and 36B by the ram air ducts. Thus, the fluid of
system 10 is cooled by circuits 36A and 36B before flowing into
liquid loads 14 and 16 through line 46C.
[0011] The pack bays of liquid loads 14 and 16 contain
environmental control systems that provide conditioned air to
passenger areas of the aircraft cabin. Fluid line 46E connects
liquid load 16 in parallel with liquid load 14. The chilled cooling
fluid of system 10 absorbs heat from heat exchangers 28 and 30,
through which a separate fluid flows in lines 50 and 52,
respectively. Liquid system 10 may include other systems that dump
heat to or take heat from fluid of lines 46A-46D either directly or
through conduction. For example, system 10 may be linked to galley
cooling systems of the aircraft between liquid loads 18 and 14.
Examples of various liquid loads used in conjunction with liquid
circulation loops are described in U.S. Pat. No. 4,550,573, which
is assigned to United Technologies Corporation, and U.S. Pat. Nos.
6,415,595 and 7,334,422, which are assigned to Hamilton Sundstrand
Corporation, all of which are incorporated by reference. In
exemplary embodiments, a liquid circulates through a closed loop
system that transfers and removes heat from the system.
[0012] System 10 includes various other components, including
valves and sensors, for maintaining operation of system 10. Valves
32 and 34 operate to bring liquid loads 14 and 16 into fluid
communication with liquid system 10 properly. Diverter valve 34 can
be closed to bypass loads 14 and 16 such as for safety, maintenance
or performance issues. Check valve 32 prevents fluid within lines
46A-46E from flowing backwards through system 10. Relief valve 26,
which may be placed anywhere along fluid lines 46A-46D, allows
fluid to escape from line 46D when pressure within system 10
exceeds a maximum pressure. Pressure sensor 42 and temperature
sensor 44 provide input signals to an aircraft controller to
monitor the performance of system 10. For example, the speed of
pump 22 can be adjusted based on the pressures and temperatures of
system 10. Also, sensors 42 and 44 allow calculations to be
performed to determine fluid levels in system 10.
[0013] Reservoir 24 comprises a variable enclosed volume that
allows the fluid within system 10 to expand. For example, cooling
fluid within system 10 retains heat from liquid loads 14-18, which
thermally expands the fluid. Furthermore, ambient heat from
atmospheric conditions expands the volume of the fluid within
system 10. The thermal expansion of the fluid exceeds the total
system volume provided by lines 46A-46F and pump 22. Specifically,
system 10 operates optimally when fluid fills the system and air is
omitted from the system. Thus, when the fluid expands, reservoir 24
provides extra system volume that adjusts so system 10 is always
operating optimally. Without a reservoir, thermal expansion of the
fluid would increase the pressure of system 10 to operate valve 26.
Fluid would thus be expelled from system 10 as valve 26 opens at
the maximum pressure. However, the expelled fluid would be lost
such that upon a reduction in the temperature of the fluid, system
10 would not be full and would be operating below optimum
conditions. Reservoir 24 thus allows system 10 to operate optimally
during widely varying ranges of conditions. Thus, the capacity of
reservoir 24 is closely matched to the expected operating
conditions of system 10 and the particular liquid loads to which
system 10 is connected.
[0014] It is sometimes desirable to change the configuration of
system 10. For example, more cooling loops, similar to circuits 36A
and 36B, may be added to liquid load 18. These loads may require
system 10 to carry a greater volume of cooling fluid, as might be
needed for greater lengths of fluid lines or for increases in
cooling performance. Additionally, the configuration of system 10
may change as system 10 is incorporated into a different aircraft
airframe. It is, however, desirable to maintain system 10 as close
as possible to original design specifications to avoid the need to
have to recertify existing components to performance and safety
specifications. In particular, it is difficult to redesign pump
package 12 because pump 22 and reservoir 24 are incorporated into a
single housing, as is described in more detail with reference to
FIG. 2. Thus, it is not possible to simply expand the capacity of
reservoir 24 without redesigning pump package 12. Auxiliary
reservoir 20 of the present invention provides system 10 with
additional volumetric capacity beyond what is provided by reservoir
24. Auxiliary reservoir 20 can be linked into system 10 along any
portion of lines 46A-46E. Thus, system 10 can be reconfigured and
repackaged for easy incorporation into other airframes.
Furthermore, the construction of pump package 12 need not be
disturbed to do so. Auxiliary reservoir 20 is also designed to not
disturb the performance of reservoir 24 until auxiliary capacity is
needed, as is described with reference to FIG. 2.
[0015] FIG. 2 shows a diagrammatic illustration of pump package 12,
separate auxiliary reservoir 20, pump 22, primary reservoir 24,
liquid load 14 and valve 26. Auxiliary reservoir 20 includes
housing 54, bellows 56, spring 58 and cap 60. Pump package 12
includes housing 62, reservoir cylinder 64, piston 66, inlet
chamber 68, outlet chamber 70 and level sensor 71. FIG. 2 is shown
to illustrate the present invention including the various volumes
within each component and is not shown to scale.
[0016] Low pressure system fluid F.sub.LP enters liquid load 14
through fluid line 46C after having passed through liquid load 18
(FIG. 1). Within liquid load 14, F.sub.LP is in thermal
communication with heat exchanger 28 (FIG. 1) whereby heat is
absorbed into fluid F.sub.LP. After passing through liquid load 14,
low pressure fluid F.sub.LP is ready to be re-circulated through
system 10 to continue the cycle of heat removal. Low pressure fluid
F.sub.LP flows from liquid load 14 to pump package 12 through
liquid line 46D. Along the way to pump package 12, fluid F.sub.LP
passes valve 26 and auxiliary reservoir 20 and exerts pressure on
valve 26 and reservoir 20 commensurate with system pressure at that
point. As discussed below, valve 26 and reservoir 20 open at
specific pressures to ensure functionality of system 10. As shown
in FIG. 2, auxiliary reservoir 20 is shown in an evacuated state
where no fluid is stored.
[0017] At pump package 12, low pressure fluid F.sub.LP enters inlet
chamber 68 within housing 62. Specifically, low pressure fluid
F.sub.LP enters cylinder 64 where piston 66 exerts atmospheric
pressure P.sub.A on chamber 68. The lowest pressure within system
10 occurs at inlet chamber 68. As pressure within system 10 rises
due to increased temperature of fluid F.sub.LP, fluid within inlet
chamber 68 exerts a force on piston 66. Fluid continues into pump
22 from chamber 68. Within pump 22, the fluid becomes pressurized
using any conventional compression means. For example, pump 22 may
comprise rotary vane pump or a centrifugal pump. Furthermore, pump
22 may comprise a tandem pump unit for reasons of redundancy and
safety.
[0018] Fluid pressurized within pump 22 is discharged into outlet
chamber 70. High pressure fluid F.sub.HP exerts a force on piston
66 such that pressurization of reservoir 24 is provided by
operation of pump 22. Thus, primary reservoir 24 comprises a
bootstrap reservoir as is known in the art. For example, U.S. Pat.
No. 4,691,739 to Gooden describes a typical bootstrap reservoir
configuration. Although described with respect to an integrated
pump and bootstrap-charged reservoir, any pump reservoir
combination may be used. For example, an integrated pump and
gas-charged reservoir is described in U.S. Pat. No. 4,906,166,
which is assigned to Sundstrand Corporation. In yet other
embodiments, pump 22 and primary reservoir 24 are not integrated.
In any embodiment, the highest pressure in system 10 occurs at the
outlet of pump 22, which is outlet chamber 70 for the described
embodiment. From outlet chamber 70, high pressure fluid F.sub.HP
leaves reservoir 24 and enters fluid line 46A for circulation
through system 10 and returning to liquid load 14 as low pressure
fluid F.sub.LP.
[0019] As heat accumulates in low pressure fluid F.sub.LP due to
system operation and increases in ambient temperature, the volume
of F.sub.LP increases. System 10 is designed to operate fully
charged, i.e. with no empty space in lines 46A-46E or pump 22. As
such, volumetric expansion of F.sub.LP due to temperature increases
causes the pressure within system 10 to increase. Primary reservoir
24 and auxiliary reservoir 20 provide extra volumetric capacity to
system 10 to accommodate thermal expansion of fluid F.sub.LP. In
particular, primary reservoir 24 and auxiliary reservoir 20 provide
active or real-time increases in system capacity so that system 10
is always fully charged. Furthermore, activation of primary
reservoir 24 and auxiliary reservoir 20 is staged such that
utilization of the volumetric capacity of auxiliary reservoir 20
occurs only after the volumetric capacity of primary reservoir 24
is maxed out.
[0020] As pressure within system 10 rises, pressure within inlet
chamber 68 rises, overcoming atmospheric pressure P.sub.A and
pressure of high pressure fluid F.sub.HP on piston 66. Piston 66
thus rises (as shown in FIG. 2) within cylinder 64 such that more
space within cylinder 64 is allocated to inlet chamber 68 and less
space is allocated to outlet chamber 70. Level sensor 71 provides
input to a system controller that indicates the position of piston
55 and/or the liquid level in cylinder 64. The input can be
referenced with pressure and temperature data sensed by pressure
sensor 42 and temperature sensor 44 (FIG. 1) to verify operation of
system 10. However, piston 66 can only traverse cylinder 64 until
piston flange 72 engages cylinder stops 74. At such point, the
volumetric capacity of primary reservoir 24 becomes maxed out, or
reaches a threshold level where utilization of auxiliary reservoir
20 is initiated. Thus, primary reservoir 24 has an operating range
extending from the minimum operating pressure of system 10 to a
pressure below the maximum operating pressure of system 10. Upon
initiation of system 10, pressure at inlet chamber 68 will rise to
the minimum system operating pressure. Atmospheric pressure P.sub.A
and the pressure of high pressure fluid F.sub.HP will maintain
piston 66 in a collapsed or fully downward position within cylinder
64, insofar as the liquid level in the primary reservoir 24 will
allow. As system 10 increases operating temperature above the
minimum due to operating or ambient conditions, piston 66 rises
until the threshold pressure is reached.
[0021] Auxiliary reservoir 20 comprises a spring-charged reservoir
in which spring 58 biases the position of cap 60 against housing
54. Spring 58 maintains the volumetric capacity within housing 54,
the space between cap 60 and fluid line 46F, closed until the
threshold pressure is reached. Spring 58 pushes downward on cap 60
such that low pressure fluid F.sub.LP is not able to enter housing
54 through line 46F. Spring 58 has a spring force set to yield at
or above the threshold pressure of primary reservoir 24. Thus,
spring 58 will not allow cap 60 to move, making the volumetric
capacity within housing 54 unavailable, until the threshold level
is exceeded and the volumetric capacity of primary reservoir 24 is
full. As auxiliary reservoir 20 fills with fluid, bellows 56
expands and cap 60 rises within housing 54. Bellows 56 comprises a
flexible metal sleeve that hermetically seals low pressure fluid
F.sub.LP within housing 54, preventing the fluid from moving to the
back side of cap 60. Cap 60 can continue to retreat until spring 58
is fully compressed. At such point, system 10 reaches its maximum
volumetric capacity, as both primary reservoir 24 and auxiliary
reservoir 20 are full. After reservoirs 20 and 24 fill up, any
further increase in volume of low pressure fluid F.sub.LP will
cause valve 26 to release fluid from system 10. Valve 26 may
comprise any pressure relief valve as is know in the art. System 10
returns to lower operating pressures in reverse order, with
auxiliary reservoir 20 emptying completely before primary reservoir
24 reduces fluid volume. Spring 58 ensures that any fluid within
housing 54 is recharged into lines 46A-46F for circulation through
the system 10.
[0022] In other embodiments, auxiliary reservoir 20 may comprise a
gas-charged reservoir where the back side of cap 60 within housing
54 is charged with a compressible gas that acts as a spring force.
Auxiliary reservoir 20 may also be provided with additional
features such as de-aeration and bleed ports, level sensors,
temperature sensors and pressure sensors. However, auxiliary
reservoir 20 need not have a dedicated level sensor so long as
reservoir 24 is provided with level sensor 71. For example,
auxiliary reservoir 20 can be sized to provide volume for the
extreme upper limit of the operating pressure range of system 10.
Thus, auxiliary reservoir 20 need only be engaged by system 10 a
small amount of time. When level sensor 71 indicates primary
reservoir 24 is at full capacity, a system controller will be able
to determine that auxiliary reservoir 20 went into use. After
returning to pressures within the operating range of primary
reservoir 24, the system controller can verify fluid levels in
system 10 by rechecking data from level sensor 71, pressure sensor
42 and temperature sensor 44. If fluid levels are indicated as
being low, the controller can determine that pressures within
system 10 exceeded the maximum pressure such that valve 26 was
activated and fluid was lost. Thus, a system operator can be
alerted by the controller to the fact that system 10 may need
maintenance.
[0023] Auxiliary reservoir 20 increases the volumetric fluid
capacity of system 10 without interfering with the installation or
operation of system 10 and pump package 12. Auxiliary reservoir 20
can be spliced into fluid line 46D at any position. Any space
within an airframe available may be used to accommodate auxiliary
reservoir 20. Thus, the addition of additional cooling demands,
such as an additional cooling circuit being connected to liquid
load 18, can be easily accommodated. Furthermore, the packaging of
pump 22 and 24 need not be disturbed to increase capacity of system
10. System 10, including auxiliary reservoir 20, can be filled by
simply filling system 10 with fluid until valve 26 releases fluid
such that all air is purged from system 10, as would be done
without auxiliary reservoir 20. The timing of the activation of
auxiliary reservoir 20 allows pump package 12 to function as if
auxiliary reservoir 20 were not part of the system when operating
below the threshold level. Thus, the pumping performance of pump 22
will remain unaffected below the threshold level.
[0024] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *