U.S. patent application number 14/709866 was filed with the patent office on 2016-11-17 for active system for bearing oil damper supply and vibration control.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is United Technologies Corporation. Invention is credited to Francis Parnin.
Application Number | 20160333736 14/709866 |
Document ID | / |
Family ID | 55970865 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160333736 |
Kind Code |
A1 |
Parnin; Francis |
November 17, 2016 |
ACTIVE SYSTEM FOR BEARING OIL DAMPER SUPPLY AND VIBRATION
CONTROL
Abstract
A bearing damping system includes a pump configured to pump a
fluid. The system further includes a variable position valve having
a plurality of open positions each configured to generate different
pressures in the fluid downstream from the variable position valve.
The system also includes a bearing assembly. The bearing assembly
includes a bearing housing. The bearing assembly also includes a
stationary bearing race positioned within the bearing housing. The
bearing assembly also includes a rotating bearing race spaced apart
from the stationary bearing race and configured to be attached to a
rotating component. A bearing element is disposed between the
stationary bearing race and the bearing housing. A fluid
compartment is defined by the space between the bearing housing and
the stationary race and is configured to receive the fluid from the
second conduit.
Inventors: |
Parnin; Francis; (Suffield,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Hartford |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
55970865 |
Appl. No.: |
14/709866 |
Filed: |
May 12, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16C 19/527 20130101;
F05D 2270/303 20130101; F16C 35/067 20130101; F05D 2240/50
20130101; F05D 2270/309 20130101; F01D 25/164 20130101; F05D
2270/334 20130101; F01D 25/20 20130101; F16C 2360/23 20130101; F05D
2260/96 20130101; F05D 2240/90 20130101; F16C 19/06 20130101; F05D
2220/32 20130101; F05D 2270/301 20130101; F16F 15/0237 20130101;
F05D 2240/54 20130101; F16C 27/045 20130101 |
International
Class: |
F01D 25/16 20060101
F01D025/16; F16C 39/04 20060101 F16C039/04; F16C 35/04 20060101
F16C035/04; F16C 19/52 20060101 F16C019/52; F16C 19/06 20060101
F16C019/06 |
Claims
1. A bearing damping system comprising: a pump configured to pump a
fluid through the system; a variable position valve connected to
the pump by a first conduit and having a plurality of open
positions each configured to generate a different flow of the fluid
downstream from the variable position valve; and a bearing assembly
connected to the variable position valve by a second conduit and
comprising: a bearing housing having an outer surface and an inner
surface, the bearing housing configured to be attached to a
stationary structure; a stationary bearing race having an outer
surface and an inner surface and positioned within the bearing
housing; a rotating bearing race having an outer surface and an
inner surface spaced apart from the stationary bearing race and
configured to be attached to a rotating component; a bearing
element disposed between the inner surface of the stationary
bearing race and the outer surface of the rotating bearing race;
and a fluid compartment defined by the space between the inner
surface of the bearing housing and the outer surface of the
stationary race and configured to receive the fluid from the second
conduit.
2. The bearing damping system of claim 1, wherein the variable
position valve comprises: a pressure regulating valve having an
adjustable diaphragm disposed between the first conduit and the
second conduit.
3. The bearing damping system of claim 1, wherein the variable
position valve comprises: a plate movably disposed within the
variable position valve to generate a plurality of flow areas
through the variable position valve.
4. The bearing damping system of claim 1, wherein the variable
position valve comprises: a sleeve disposed in the first conduit
wherein the sleeve has a plurality of orifices; and a poppet
movably disposed within the sleeve and configured to decrease a
flow area though the sleeve by blocking at least one orifice.
5. The bearing damping system of claim 1, wherein the variable
position valve is configured to restrict a flow of the fluid into
the fluid compartment when a fluid pressure into the compartment
exceeds a threshold pressure.
6. The bearing damping system of claim 1, wherein the variable
position valve is configured to increase a flow of the fluid into
the fluid compartment when the fluid pressure into the compartment
falls below a threshold pressure.
7. The bearing damping system of claim 1, and further comprising: a
controller configured to monitor a parameter and actuate the
variable position valve to maintain an optimum fluid pressure into
the fluid compartment, wherein the parameter monitored by the
controller is selected from the group consisting of: a stationary
structure vibration rate, a component rotation rate, a fluid
pressure in the first conduit, a fluid pressure in the second
conduit, a fluid pressure in the fluid compartment, a fluid
viscosity in the first conduit, a fluid viscosity in the second
conduit, a fluid viscosity in the fluid compartment, a fluid
temperature in the fluid compartment, a fluid temperature in the
first conduit, a fluid temperature in the second conduit, and
combinations thereof.
8. The bearing damping system of claim 1, and further comprising:
an accelerometer disposed on the stationary structure configured to
measure the stationary structure vibration rate.
9. A gas turbine engine comprising: a stationary section; a
rotating section joined to a shaft; a bearing housing having a
radially outer surface and a radially inner surface and attached to
the stationary section of the gas turbine engine; a stationary
bearing race having a radially outer surface and a radially inner
surface and spaced radially inward from the bearing housing; a
rotating bearing race having a radially outer surface and a
radially inner surface and spaced radially inward from the
stationary bearing race and attached to the shaft; a bearing
element disposed between the radially inner surface of the
stationary bearing race and the radially outer surface of the
rotating bearing race; a fluid compartment defined by the space
between the radially inner surface of the bearing housing and the
radially outer surface of the stationary race; a pump configured to
pump a fluid into the fluid compartment; and a variable position
valve having a plurality of open positions configured to generate a
plurality of fluid flows into the fluid compartment.
10. The gas turbine engine of claim 9, wherein the variable
position valve is disposed between the fluid compartment and the
pump.
11. The gas turbine engine of claim 9, wherein the variable
position valve regulates a flow of the fluid by increasing or
decreasing a size of a valve flow area.
12. The gas turbine engine of claim 11, wherein the variable
position is configured to increase the size of the valve flow area
when a fluid pressure into the fluid compartment falls below a
threshold pressure.
13. The gas turbine engine of claim 11, wherein the variable
position valve is configured to decrease the size of the valve flow
area when a fluid pressure into the fluid compartment exceeds a
threshold pressure.
14. The gas turbine engine of claim 10, and further comprising: a
controller that actuates the variable position valve based on a
parameter selected from the group consisting of: a stationary
structure vibration rate, a shaft rotation rate, a fluid pressure
between the pump and the variable position valve, a fluid pressure
between the variable position pump and the fluid compartment, a
fluid pressure in the fluid compartment, a fluid viscosity, a fluid
temperature, and combinations thereof.
15. The gas turbine engine of claim 14, wherein the stationary
structure vibration rate is measured by an accelerometer.
16. The gas turbine engine of claim 10, wherein the bearing element
is a ball or a roller.
17. A method of adjusting a stiffness of a fluid damped bearing,
the method comprising: pumping a fluid through a variable position
valve having a plurality of open positions; sensing a parameter
relating to a vibration rate of a rotating component; actuating a
variable position valve in response to the sensed parameter to
control a flow of a fluid; and routing the fluid from the variable
position valve to a fluid compartment formed between a bearing
housing and a stationary race of the fluid damped bearing.
18. The method of claim 17, wherein the parameter is selected from
the group consisting of: a stationary structure vibration rate, a
component rate of rotation, a fluid viscosity, a fluid temperature,
a fluid pressure, and combinations thereof.
19. The method of claim 17, and further comprising the step of:
reducing a flow of the fluid into the fluid damped bearing when a
fluid pressure into the compartment exceeds a threshold
pressure.
20. The method of claim 17, and further comprising the step of:
increasing the flow of the fluid when a fluid pressure into the
compartment falls below a threshold pressure.
Description
BACKGROUND
[0001] Gas turbine engines can include fluid damped bearings to
help maintain vibration and displacement of rotating components
within acceptable limits. Typically, these fluid damped bearings
are fed oil from the engine oil system and accept the oil at a
pressure generated by the system. Typical systems regulate fluid
flow to the fluid damped bearing with a valve that switches between
on and off positions. In some cases, however, alternating between
on and off positions exclusively can cause the oil flow rate to
stray from an optimal flow rate to a rate that is either too high
or too low. Either condition can lead to undesired vibration and
displacement of rotating components during operation of the gas
turbine engine. There is, accordingly, a need for a fluid damped
bearing system that can help maintain an optimum flow of fluid to
the fluid damped bearing during operation of the gas turbine
engine.
SUMMARY
[0002] According to one embodiment of this disclosure a bearing
damping system includes a pump configured to pump a fluid through
the system. The system further includes a variable position valve
connected to the pump by a first conduit and having a plurality of
open positions each configured to generate a different flow in the
fluid downstream from the variable position valve. The system also
includes a bearing assembly connected to the variable position
valve by a second conduit. The bearing assembly includes a bearing
housing having an outer surface and an inner surface. The bearing
housing is configured to be attached to a stationary structure. The
bearing assembly also includes a stationary bearing race having an
outer surface and an inner surface and is positioned within the
bearing housing. The bearing assembly also includes a rotating
bearing race having an outer surface and an inner surface spaced
apart from the stationary bearing race and configured to be
attached to a rotating component. A bearing element is disposed
between the inner surface of the stationary bearing race and the
outer surface of the rotating race. A fluid compartment is defined
by the space between the inner surface of the bearing housing and
the outer surface of the stationary race and is configured to
receive the fluid from the second conduit.
[0003] According to another embodiment of this disclosure a gas
turbine engine includes a stationary section and a rotating section
joined to a shaft. The gas turbine engine also includes a bearing
housing having a radially outer surface and a radially inner
surface. The bearing housing is attached to the stationary section
of the gas turbine engine. A stationary bearing race having a
radially outer surface and a radially inner surface is spaced
radially inward from the bearing housing. A rotating bearing race
having a radially outer surface and a radially inner surface is
spaced radially inward from the stationary bearing race and
attached to the shaft. A bearing element is disposed between the
radially inner surface of the stationary bearing race and the
radially outer surface of the rotating bearing race. A fluid
compartment is defined by the space between the radially inner
surface of the bearing housing and the radially outer surface of
the stationary race. The gas turbine engine also includes a pump
configured to pump a fluid into the fluid compartment. The gas
turbine engine further includes a variable position valve disposed
between the fluid compartment and the pump. The variable position
valve has a plurality of open positions configured to generate a
plurality of fluid flows within the fluid compartment.
[0004] According to yet another embodiment of the disclosure a
method of adjusting a stiffness of a fluid damped bearing includes
the step of pumping a fluid through a variable position valve
having a plurality of open positions. The method further includes
the step of sensing a parameter relating to a vibration rate of a
rotating component. The method also includes the step of actuating
a variable position valve in response to the sensed parameter to
control a flow of a fluid. The method additionally includes the
step of routing the fluid from the variable position valve to a
fluid compartment formed between a bearing housing and a stationary
race of the fluid damped bearing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a sectional view of a gas turbine engine.
[0006] FIG. 2 is a perspective sectional view of a ball bearing
including a fluid damper compartment.
[0007] FIG. 3 is a sectional view of the ball bearing taken along
line 2-2 from FIG. 2.
[0008] FIG. 4 is a schematic view of a bearing damping system with
a pressure regulating valve regulating fluid flow.
[0009] FIG. 5A is a schematic view of a bearing damping system with
a variable position valve regulating fluid flow in a first open
position.
[0010] FIG. 5B is a schematic view of a bearing damping system with
the variable position valve of FIG. 5A in a second open
position.
[0011] FIG. 6A is a schematic view of a bearing damping system with
an alternative variable position valve regulating fluid flow in a
first open position.
[0012] FIG. 6B is a schematic view of a bearing damping system with
the variable position valve of FIG. 6A in a second open
position.
[0013] FIG. 7 is a schematic view of a bearing damping system with
an electronically controlled variable position valve.
[0014] FIG. 8 is a schematic view of an alternative bearing damping
system having a valve disposed on a bypass line regulating fluid
flow.
[0015] FIG. 9 is a flow diagram showing a method of adjusting a
stiffness of a fluid damped bearing.
DETAILED DESCRIPTION
[0016] This disclosure is directed towards fluid damped bearings.
More particularly, this disclosure is directed towards regulating
the fluid pressure in fluid damped bearings.
[0017] FIG. 1 is a sectional view of gas turbine engine 10. Gas
turbine engine (or turbine engine) 10 includes a power core with
compressor section 12, combustor 14 and turbine section 16 arranged
in flow series between upstream inlet 18 and downstream exhaust 20.
Compressor section 12 and turbine section 16 are arranged into a
number of alternating stages of rotor airfoils (or blades) 22 and
stator airfoils (or vanes) 24.
[0018] In the turbofan configuration of FIG. 1, propulsion fan 26
is positioned in bypass duct 28, which is coaxially oriented about
the engine core along centerline (or turbine axis) C.sub.L. An
open-rotor propulsion stage 26 may also be provided, with turbine
engine 10 operating as a turboprop or unducted turbofan engine.
Alternatively, fan rotor 26 and bypass duct 28 may be absent, with
turbine engine 10 configured as a turbojet or turboshaft engine, or
an industrial gas turbine. Gas turbine engine 10 can also include
geared architecture such as a fan drive gear system.
[0019] In the two-spool, high bypass configuration of FIG. 1,
compressor section 12 includes low pressure compressor (LPC) 30 and
high pressure compressor (HPC) 32, and turbine section 16 includes
high pressure turbine (HPT) 34 and low pressure turbine (LPT) 36.
Low pressure compressor 30 is rotationally coupled to low pressure
turbine 36 via low pressure (LP) shaft 38, forming the LP spool or
low spool. High pressure compressor 32 is rotationally coupled to
high pressure turbine 34 via high pressure (HP) shaft 40, forming
the HP spool or high spool.
[0020] Flow F at inlet 18 divides into primary (core) flow F.sub.P
and secondary (bypass) flow F.sub.S downstream of fan rotor 26.
Primary flow F.sub.P is compressed in low pressure compressor 30
and high pressure compressor 32, and then mixed with fuel in
combustor 14 and ignited to generate hot combustion gas. The
combustion gas expands to provide rotational energy in high
pressure turbine 34 and low pressure turbine 36, driving high
pressure compressor 32 and low pressure compressor 30,
respectively. Expanded combustion gases exit through exhaust
section (or exhaust nozzle) 20, which can be shaped or actuated to
regulate the exhaust flow and improve thrust performance.
[0021] Low pressure shaft 38 and high pressure shaft 40 are mounted
coaxially about centerline C.sub.L, and rotate at different speeds.
Fan rotor (or other propulsion stage) 26 is rotationally coupled to
low pressure shaft 38. Each shaft is associated with at least one
bearing such as damped ball bearing 42 or damped roller bearing
44.
[0022] Turbine efficiency and performance depends on the overall
pressure ratio, defined by the total pressure at inlet 18 as
compared to the exit pressure of compressor section 12, for example
at the outlet of high pressure compressor 32, entering combustor
14.
[0023] FIG. 2 is a perspective sectional view of damped ball
bearing 42. Although FIG. 2 shows damped ball bearing 42, the
concepts described below are equally applicable to damped roller
bearing 44. FIG. 2 includes rotating race 46, which includes
rotating race radially inner surface 48 and rotating race radially
outer surface 50; bearing element 52, stationary race 54, which
includes stationary race radially inner surface 56 and stationary
race radially outer surface 58; bearing housing 60, which includes
bearing housing radially inner surface 62 and bearing housing
radially outer surface 64; and fluid compartment 66.
[0024] Low pressure shaft 38 defines a central rotational axis of
gas turbine engine 10. As stated above, low pressure shaft 38
drives rotation of propulsion fan 26, low pressure compressor 30,
and low pressure turbine 36 which define the LP spool. Although low
pressure shaft 38 is depicted in FIG. 2, this description can also
apply to high pressure shaft 40 which drives rotation of high
pressure compressor 32 and high pressure turbine 34 which define
the HP spool. Damped ball bearing 42 surrounds low pressure shaft
38. Damped ball bearing 42 helps to facilitate rotation of low
pressure shaft 38.
[0025] Rotating race 46 of damped ball bearing 42 is annularly
shaped and circumscribes low pressure shaft 38. Rotating race 46
includes rotating race radially inner surface 48 and rotating race
radially outer surface 50. Low pressure shaft 38 is joined to
rotating race inner surface 48. Rotating race radially outer
surface 50 interfaces with bearing element 52. As depicted in FIG.
2, bearing element 52 is a ball but in other embodiments bearing
element 52 can be a cylindrical roller or a tapered roller
bearing.
[0026] Stationary race 54 of damped ball bearing 42 circumscribes
and is spaced apart from rotating race 46. Stationary race 54
includes radially inner surface 56 and radially outer surface 58.
Stationary race radially inner surface 56 is spaced apart from
rotating race radially outer surface 50 and bearing element 52 is
disposed therebetween.
[0027] Bearing housing 60, of damped ball bearing 42, circumscribes
stationary race 54 and includes bearing housing radially inner
surface 62 and bearing housing radially outer surface 64. Bearing
housing radially inner surface 62 is joined to stationary race
radially outer surface 58. A space is formed between bearing
housing radially inner surface 62 and stationary race radially
outer surface 58 which defines fluid compartment 66. Bearing
housing radially outer surface 64 is joined to a non-rotating
stationary structure of gas turbine engine 10.
[0028] FIG. 3 is a sectional view of damped ball bearing 42 taken
along line 2-2 from FIG. 2. FIG. 3 additionally illustrates radial
extensions 68. Radial extensions 68 extend from the axial ends of
stationary race radially outer surface 58. Radial extensions 68 are
joined to bearing housing radially inner surface 62 and seal fluid
compartment 66. In other embodiments of damped ball bearing 42
radial extensions 68 can be replaced with piston rings or
O-rings.
[0029] In operation, low pressure shaft 38 rotates as core air flow
flows through gas turbine engine 10. Rotating race 46 rotates along
with low pressure shaft 38. The rotation is facilitated by bearing
elements 52. Bearing elements 52 also help to keep low pressure
shaft 38 in a proper position because they are sized to fit between
rotating race 46 and stationary race 54 so as to maintain contact
with both races 46 and 54.
[0030] As low pressure shaft 38 rotates, it can vibrate and impart
relatively strong forces radially outward from the central axis of
gas turbine engine 10. These forces are transmitted radially
outward to rotating race 46. The forces are then transmitted
radially outward to bearing elements 52. From bearing elements 52,
the forces are transmitted radially outward to stationary race
54.
[0031] Fluid compartment 66 is filled with a fluid such as engine
oil. The fluid is typically pressurized and has a low viscosity. As
an example, engine oil can be supplied to fluid compartment 66 at a
temperature ranging from approximately 93.3 degrees Celsius (200
degrees Fahrenheit) to approximately 140.5 degrees Celsius (285
degrees Fahrenheit). At these temperatures the viscosity of the oil
can range from approximately 5.8 centistokes to approximately 2.8
centistokes. Fluid 74 in fluid compartment 66 acts to dampen the
vibrational forces described above. The damping effect is
generated, in part, by the fluid in fluid compartment 66 being
squeezed from one location in compartment 66 to another as
stationary race 54 translates towards bearing housing 60 due to the
vibration of low pressure shaft 38. As a result of the damping
effect provided by the fluid, the severity of the vibrational
forces projecting radially outward to bearing housing 60 are
lessened. As a result, a less severe vibrational force is
translated radially outward from bearing housing 60 to other
structures in gas turbine engine 10 and the degree to which low
pressure shaft 38 vibrates is also lessened.
[0032] The degree to which fluid in fluid compartment 66 dampens
vibrations is a function of many factors. One factor is the amount
of fluid 74 in fluid compartment 66. The degree to which fluid
compartment 66 is filled with fluid 74 can be referred to as the
fill volume of fluid compartment 66. The amount of fluid 74 in
fluid compartment 66 is a function of the rate of flow of fluid 74
into compartment 66 as compared to the rate of flow of fluid 74 out
of compartment 66. The flow rate of fluid 74 into fluid compartment
66 is largely driven by the pressure of fluid 74 supplied to fluid
compartment 66. This pressure can be referred to as a feed
pressure.
[0033] If the feed pressure is too low, then the amount of fluid 74
in fluid compartment 66 will not be able to sufficiently absorb the
vibrational forces that are transmitted to it. These conditions
give rise to a soft damper. If, on the other hand, the feed
pressure of fluid 74 is too high, then the fluid compartment 66
will be over full and vibrational forces will be able to easily
translate through the fluid to bearing housing 60. These conditions
give rise to a stiff damper. A fluid feed pressure should be
maintained to keep fluid compart 66 at an optimum fill volume that
is between the soft and stiff damper conditions.
[0034] Fluid viscosity is another factor that is relevant to the
fluid's ability to dampen vibrations. The more viscous the fluid is
the less likely it is to be displaced too easily by vibrational
forces. If the fluid's viscosity is too high however, such that
fluid 74 does not move around in fluid compartment 66, then the
vibrational forces will translate through it. Fluid viscosity can
also be reduced during operation of low pressure shaft 38 if the
fluid supply temperature is elevated.
[0035] FIG. 4 is a schematic view of bearing damping system 70A.
FIG. 4 shows shaft 38, pump 72, fluid 74, first conduit 76,
variable position valve 78A, diaphragm 80, second conduit 82, third
conduit 84, and sensing line 86.
[0036] Pump 72 contains fluid 74 and is connected to first conduit
76. First conduit 76 leads away from pump 72 and connects to
variable position valve 78A. Variable position valve 78A includes
diaphragm 80. Second conduit 82 leads away from variable position
valve 78A, passes through bearing housing 60, and terminates in
fluid compartment 66. Third conduit 84 branches from first conduit
76 and leads to a component of gas turbine engine 10. Sensing line
86 is connected on one end to second conduit 82 and to the backside
of diaphragm 80 on another end.
[0037] In operation, fluid 74 is pumped through first conduit 76 by
pump 72. Pump 72 produces a continuous flow of fluid 74 through
bearing damping system 70A. The pressure of fluid 74 in first
conduit 76 can depend on the diameter of first conduit 76, flow
rate of fluid 74, viscosity of fluid 74, and the temperature of
fluid 74. Fluid 74 can flow into third conduit 84 which takes fluid
74 to other components of gas turbine engine 10 that require fluid
74 (e.g., for lubrication purposes). Fluid 74 that does not enter
third conduit 84 enters variable position valve 78A.
[0038] Variable position valve 78A is disposed between first
conduit 76 and second conduit 82. Variable position valve 78A has a
plurality of open positions. Each open position either contracts or
expands a flow area in variable position valve 78A for fluid 74 to
pass through in order to enter second conduit 82. The flow of fluid
74 through variable position valve 78A is reduced when fluid 74
passes through a flow area having a smaller diameter than first
conduit 76. Thus the flow of fluid 74 in second conduit 82 can be
controlled by alternating variable position valve 78A between the
plurality of open positions.
[0039] Variable position valve 78A as shown in in FIG. 4 is a
pressure sensing valve that includes diaphragm 80, which regulates
flow through valve 78A. Diaphragm 80 is pressure actuated. That is,
if a pressure on the back side of diaphragm 80 exceeds a threshold
value, then diaphragm 80 is actuated to constrict the flow area of
variable position valve 78A through which fluid 74 can pass. If, on
the other hand, the pressure on the back side of diaphragm 80 is
less than a threshold value, then diaphragm 80 is actuated to
expand the flow area that fluid 74 can pass through in variable
position valve 78A. In other embodiments of variable position valve
78A diaphragm 80 can be replaced with a poppet.
[0040] Communication of the fluid pressure to the back side of
diaphragm 80 is facilitated by sensing line 86. Sensing line 86 can
be connected to second conduit 82 or fluid compartment 66 on one
end and is connected to the back side of diaphragm 80 on the other
end. The fluid pressure in either second conduit 82 or fluid
compartment 66 will then be communicated to diaphragm 80 which is
actuated as described above to increase or decrease the flow area
in variable position valve 78A for fluid 74 to flow through.
[0041] After passing through variable position valve 78A, fluid 74
enters second conduit 82. Fluid 74 flows through second conduit 82
into fluid compartment 66. As stated above, variable position valve
78A controls the flow of fluid 74 that is fed into second conduit
82 and fluid compartment 66. In controlling the flow of fluid 74
variable position valve 78A can also control the pressure of fluid
74 downstream from valve 78A. For example the flow of fluid 74 can
be increased so as to increase the pressure of fluid 74 fed into
fluid compartment 66.
[0042] The flow of fluid 74 can also be decreased in order to
decrease the volume of fluid 74 within fluid compartment 66. By
decreasing the flow of fluid 74 into fluid compartment 66 the fluid
volume inside compartment 66 will decrease because fluid 74 exits
fluid compartment 66 during operation of gas turbine engine 10.
Thus, if the flow of fluid 74 is restricted, then incoming fluid
will not replace fluid that exited fluid compartment 66 at a fast
enough rate to maintain the fill volume of fluid compartment
66.
[0043] FIG. 5A is a schematic view of bearing damping system 70B
including variable position valve 78B. Variable position valve 78B
includes multiple orifice sleeve 88 having first plurality of
orifices 94, second plurality of orifices 95, and outlet 96. Poppet
91 and spring 100 are also shown. Combustor bleed gas 75 is also
shown.
[0044] Sleeve 88 is fastened within first conduit 76. As stated
above sleeve 88 includes first and second pluralities of orifices
94 and 95. As shown, each plurality of orifices is formed from a
group of three orifices. In other embodiments each plurality of
orifices 94 and 95 can include other plural numbers of orifices.
Outlet 96 is formed in an end of sleeve 88 near second conduit 82.
Poppet 91 is solid and is disposed within sleeve 88. Spring 100 is
attached to sleeve 88 near outlet 96 and to poppet 91. Sensing line
86 runs from second conduit 82 to the backside of poppet 91.
[0045] In operation, fluid 74 passes through bearing damping system
70B in much the same way as in bearing damping system 70A. One
difference between the two systems is that the feed pressure of
fluid 74 is controlled by variable position valve 78B in bearing
damping system 70B. In the embodiment shown in FIG. 5, variable
position valve 78B has two open positions and one closed position.
Variable position valve 78B is fully open in the first open
position. This is shown in FIG. 5A as poppet 91 is not blocking any
of first or second plurality of orifices 94 or 95. Thus, the flow
area through sleeve 88 is at a maximum.
[0046] FIG. 5B shows variable position valve 78B in the second open
position. As shown, in the second open position poppet 91 blocks
first plurality of orifices 94. As a result, the feed pressure and
flow of fluid 74 will be less than the pressure and flow of fluid
74 in first conduit 76. This is because the flow area through
sleeve 88 is decreased. If variable position valve 78B is in the
closed position, then second plurality of orifices 95 will be
blocked by poppet 91. As can be understood from the above
discussion, the feed pressure and flow of fluid 74 inside fluid
compartment 66 can be controlled by adjusting the position of
poppet 91 with respect to first and second plurality of orifices 94
and 95.
[0047] In other embodiments of variable position valve 78B
additional pluralities of orifices can be included on sleeve 88 in
order to increase the number of possible open positions in variable
position valve 78B. Additionally, the orifices forming first and
second pluralities of orifices 94 and 95 can be of uniform or
differing sizes. In still further embodiments, orifices can be
replaced with one or more elongated openings in sleeve 88. In that
case, poppet 91 can be actuated along the openings to continuously
increase or decrease the flow area through sleeve 88.
[0048] Variable position valve 78B can be actuated in many
different ways such as in response to an operating condition of gas
turbine engine 10. For example, actuation of variable position
valve 78B can be driven in response to a sensed pressure of
combustor bleed gas 75 in combustor 14. A pressure increase in
combustor 14 can lead to a higher rate of rotation in low pressure
turbine 36 which will cause low pressure shaft 38 to rotate faster
and potentially cause increased vibrations.
[0049] An increase in pressure of combustor bleed gas 75 can be
communicated to poppet 91 through sensing line 86, which is
connected to combustor 14 and the backside of poppet 91. The
pressure of combustor bleed gas 75 can cause poppet 91 to decrease
the flow area through sleeve 88 by blocking the orifices in sleeve
88. As poppet 91 is actuated to block the orifices, spring 100 is
compressed. If the pressure of combustor bleed gas 75 decreases,
then spring 100 will expand and cause poppet 91 to be actuated to
increase flow area through sleeve 88 by blocking fewer
orifices.
[0050] Based on the correlation of the pressure sensed in combustor
14 and the rotation of low pressure shaft 38, variable position
valve 78B can be configured to be actuated in order to adjust the
feed pressure into fluid compartment 66 to maintain optimal feed
pressure and fill volume in fluid compartment 66.
[0051] In addition to spring 100 actuating poppet 91 of variable
position valve 78B, poppet 91 can be actuated by a threaded screw
and bolt or by a magnet that is configured to generate a sufficient
magnetic force to actuate poppet 91.
[0052] FIG. 6A is a schematic view of bearing damping system 70C.
Bearing damping system 70C includes many of the same features as
bearing damping system 70B. One difference is variable position
valve 78C, which includes plate 89. Plate 89 is a solid plate.
Bearing damping system 70C also includes piston 92 plate, which is
connected to plate 89. Piston 92 plate is also connected to spring
100.
[0053] In operation, variable position valve 78C can be actuated to
one of a plurality of positions ranging from a fully open position
as illustrated in FIG. 6A to a fully closed position where plate 89
blocks flow of fluid 74 through variable position valve 78C. Thus,
actuating plate 89 decreases or increases the flow area through
variable position valve 78C, which determines the feed pressure of
fluid 74 into fluid chamber 66. Plate 89 can be actuated as
described above with respect to poppet 91. As shown in FIG. 6A
sensing line 86 communicates fluid pressure in second conduit 82 to
the backside of plate 89. As the pressure increases, plate 89 and
piston plate 92 are actuated down. This causes plate 89 to be
disposed between first conduit 76 and second conduit 82. As the
pressure in second conduit 82 increase, spring 100 is compressed.
If the pressure communicated by sensing line 86 decreases, then
spring 100 will not remain compressed and piston plate 92 as well
as plate 89 will be actuated up so as to increase the flow area
through variable position valve 78C. Variable position valve 78C
can, additionally, be actuated in a manner similar to that
described above with respect to variable position valve 78B. For
example, plate 89 can be actuated in response to a sensed pressure
in combustor 14 as described above with respect to bearing damping
system 70B.
[0054] FIG. 6B is a schematic view of bearing damping system 70C.
FIG. 6B shows all of the same components as FIG. 6A. As shown, a
portion of plate 89 is disposed between first conduit 76 and second
conduit 82. Thus, the flow area through variable position valve 70C
is decreased compared to the flow area though valve 70C shown in
FIG. 6A.
[0055] FIG. 7 is a schematic view of bearing damping system 70D.
Bearing damping system 70D includes electronic engine controller
102, position channel 104, pressure sensor 106, pressure feedback
channel 108, vibration sensor 110, stationary structure 112,
vibration data channel 114, temperature sensor 116, temperature
data channel 118, rotation sensor 120, and rotation data channel
122.
[0056] Plate 89 is disposed within variable position valve 78C as
described above with respect to FIGS. 6A and 6B. Electronic engine
controller 102 is disposed within gas turbine engine 10 and is
configured to receive and transmit data within bearing damping
system 70D. Electronic engine controller 102 includes position
channel 104, which communicates position commands to variable
position valve 78C and receives feedback on the position of plate
89. Pressure sensor 106 is disposed upstream of variable position
valve 78C and senses the pressure of fluid 74. The pressure data
sensed by pressure sensor 106 is communicated to electronic engine
controller 102 by pressure feedback channel 108. Vibration sensor
110 is mounted to stationary structure 112 and transmits vibration
data to electronic engine controller 102 by vibration data channel
114. Temperature sensor 116 is disposed near fluid compartment 66
and communicates temperature data to electronic engine controller
102 by temperature data channel 118. Rotation sensor 120 is
positioned near low pressure shaft 38 and communicates rotational
data to electronic engine controller 102 by rotation data channel
122.
[0057] In operation, plate 89 is actuated in response to a command
generated by electronic engine controller 102. Plate 89 can be
actuated in a manner similar to that described above with respect
to FIGS. 6A and 6B. Electronic engine controller 102 can also be
used to actuate diaphragm 80 of bearing damping system 70A or
poppet 91 of bearing damping system 70B described above.
[0058] Electronic engine controller 102 can be programed to
interpret vibration related parameters and send a command to
actuate variable position valve 78A, 78B, or 78C into any of the
open positions. Electronic engine controller 102 can also actuate
variable position valve 78A, 78B, or 78C into a closed position.
Electronic engine controller 102 can sense any one vibration
related parameter individually or any combination of vibration
related parameters discussed above simultaneously and issue an
actuation command accordingly.
[0059] Pressure sensor 106 can transmit pressure data of fluid 74
in first conduit 76 to electronic engine controller 102 by pressure
feedback channel 104. Electronic engine controller 102 can compare
that data to a programed schedule and send a position command to
variable position valve 78C by position channel 104. The position
command will cause variable position valve 78C to be actuated so as
to produce an optimal feed pressure in second conduit 82 or fluid
compartment 66. Position channel 104 can also communicate position
feedback data to electronic engine controller 102 so that
controller 102 will know what position variable position valve 78C
is in.
[0060] Pressure sensor 106 can also be disposed to be able to sense
the pressure of fluid 74 in second conduit 82 or fluid compartment
66. If electronic engine controller 102 determines that the
pressure at either location is too low, then electronic engine
controller 102 can send a command to open variable position valve
78A, 78B, or 78C to a greater degree by contracting diaphragm 80,
positioning poppet 91 to increase the flow area through sleeve 88,
or retracting plate 89 to increase the flow area through valve 78C.
Alternatively, if the pressure is too high, then electronic engine
controller 102 can send a command to close variable position valve
78A, 78B, or 78C to a greater degree by expanding diaphragm 80,
positioning poppet 91 to decrease flow through sleeve 88, or
actuating plate 89 to decrease the flow area through valve 78C.
[0061] Vibration sensor 110 is positioned on stationary structure
112. Vibration sensor 110 senses the extent to which stationary
structure 112 vibrates during operation of gas turbine engine 10.
Vibration sensor 110 can be an accelerometer. Vibration sensor 110
sends vibration data to electronic engine controller 102 by
vibration data channel 114. If electronic engine controller 102
determines that stationary structure 112 is vibrating too much,
then it can send a command to open or close variable position valve
78A, 78B, or 78C to a greater degree by contracting diaphragm 80 or
positioning poppet 91 to increase or decrease flow through sleeve
88, or by actuating plate 89 to increase or decrease the flow area
through variable position valve 78C.
[0062] Temperature sensor 116 is disposed near fluid compartment
66. Temperature sensor 116 measures the temperature of fluid 74
inside fluid compartment 66. As stated above, the temperature of
fluid 74 is relevant to its viscosity. Temperature sensor 116 sends
temperature data to electronic engine controller 102 by temperature
data channel 118. Electronic engine controller 102 can calculate
the viscosity of fluid 74 based on fluid type and fluid 74's
temperature. If electronic engine controller 102 determines that
fluid 74's viscosity is inadequate to provide damping, then it can
send a command to open or close variable position valve 78A, 78B,
or 78C. This way fluid 74 supply pressure can be adjusted to
compensate. Temperature sensor 116 can also be disposed so as to
sense a temperature of fluid 74 in first conduit 76 or second
conduit 82.
[0063] Rotation sensor 120 is disposed near low pressure shaft 38.
Rotation sensor 120 measures the rate of rotation of low pressure
shaft 38. Low pressure shaft 38's rate of rotation can be relevant
to bearing damping system 70A, 70B, 70C, or 70D in several
different ways. For example, at startup of gas turbine engine 10,
fluid in bearing damping system 70A, 70B, 70C, or 70D can be low.
This can result from pump 72 being an engine driven pump. If pump
72 is engine driven, then fluid will not be pumped into bearing
damping system 70A, 70B, 70C, or 70D when gas turbine engine 10 is
shut down. If electronic engine controller 102 senses that low
pressure shaft 38 has begun to rotate based on data from rotation
sensor 120, then it can send a command to open variable position
valve 78A, 78B, or 78C to a greater degree by contracting diaphragm
80, positioning poppet 91 to increase the flow area through sleeve
88, or retracting plate 89 to increase the flow area through valve
78C. This way flow of fluid 74 will be at its greatest magnitude
during engine start up.
[0064] In another example, if low pressure shaft 38 has a known
natural frequency, then electronic engine controller 102 can be
programmed to actuate variable position valve 78A or 78B as
described above to increase or decrease the flow of fluid 74 to
dampen any vibrations associated with reaching the natural
frequency of low pressure shaft 38. If bearing damping system 70A,
70B, 70C, or 70D is applied to high pressure shaft 40 these same
principles can apply to it.
[0065] FIG. 8 is a schematic view of bearing damping system 70E.
Bearing damping system 70E includes many of the same components as
bearing damping systems 70A, 70B, 70C, and 70D. Bearing damping
system 70E, however, differs in several respects. For example,
bearing damping system 70E includes variable position valve 78D and
bypass line 83.
[0066] In bearing damping system 70E fluid 74 is transported from
pump 72 to fluid compartment 66 by first conduit 76. Bypass line 83
branches off first conduit 76 and leads to variable position valve
78D and to other components of gas turbine engine 10.
[0067] In operation, the flow area in variable position valve 78D
can be adjusted to be one of a plurality of open positions ranging
from fully open to closed. When variable position valve 78D is
fully closed the flow of fluid 74 to fluid compartment 66 will be
at a maximum. As variable position valve 78D opens the flow area in
valve 78D increases. This results in fluid 74 flowing through
bypass line 83, which reduces the flow of fluid 74 into fluid
compartment 66. Variable position valve 78D can be actuated in any
of the manners described above with respect to variable position
valves 78A-78C.
[0068] FIG. 9 is a flow diagram showing method 124 for adjusting a
stiffness fluid damped bearing system 70A, 70B, 70C, 70D, or 70E.
As shown, method 124 includes pumping step 126, sensing step 128,
actuating step 130, and routing step 132. In pumping step 126 a
fluid is pumped through first conduit 76 through variable position
valve 78A, 78B, or 78C. In sensing step 128 a parameter relating to
a vibration rate of low pressure shaft 38 or high pressure shaft 40
is sensed. That parameter can be any parameter discussed above.
That parameter can be sensed, for example, by the pressure of fluid
74 being communicated to the back side of variable position valves
78A, 78B, or 78C as described above. The parameter can also be
sensed by one of the sensors described above communicating data to
electronic engine controller 102. In actuating step 130 variable
position valve 78A, 78B, or 78C is actuated as described above in
response to the sensed parameter. In routing step 132 fluid 74 is
routed to fluid compartment 66.
[0069] There are numerous reasons to use bearing damping system
70A, 70B, 70C, 70D, or 70E including the following non-limiting
reasons. First, by controlling the pressure and the flow of fluid
74, as described above, the damping effect of bearing damping
system 70A, 70B, 70C, 70D, or 70E can be optimized. Bearing damping
system 70A, 70B, 70C, 70D, or 70E works best when fluid 74 is at an
optimum supply pressure. That is, the volume of fluid 74 inside
fluid compartment 66 can be maintained so as not to be operating
under the soft or stiff conditions described above by using bearing
damping system 70A, 70B, 70C, 70D, or 70E. As an example fluid 74
can have pressure ranging from about 35 pounds per square inch
differential (psid) to about 100 psid. That is, the volume of fluid
74 inside fluid compartment 66 can be maintained so as not to be
operating under the soft or stiff conditions described above by
using bearing damping system 70A, 70B, 70C, 70D, or 70E.
[0070] Because variable position valves 78A, 78B, 78C, and 78D have
multiple open positions the flow of fluid 74 into fluid compartment
66 can be fine-tuned to keep the fluid volume inside compartment 66
in the optimum range during operation of gas turbine engine 10. For
example, variable position valves 78A, 78B, 78C, or 78D can be
actuated to increase the flow of fluid 74 if the fluid volume
inside fluid compartment 66 falls below a certain threshold value
causing the above referenced soft damper condition. The increase in
flow into fluid compartment 66 will increase the fluid volume
inside fluid compartment 66. Additionally, variable position valves
78A, 78B, 78C, or 78D can be actuated to decrease the flow of fluid
74 if the fluid volume inside fluid compartment 66 rises above a
certain threshold value causing the above referenced stiff damper
condition.
[0071] Additionally, the ability of variable position valves 78A,
78B, 78C, or 78D to keep damped bearing 42 at optimal conditions
can reduce the possibility of a blade rubbing event. Blade rubbing
can occur if low pressure shaft 38 vibrates enough to cause the tip
of one of the rotor blades to contact a stationary structure. This
can damage the blade and require unscheduled maintenance on gas
turbine engine 10.
[0072] Additionally, the rotor balance of gas turbine engine 10 can
change over time. That is, if the LP spool or HP spool was
initially balanced when it was installed into gas turbine engine
10, wear during operation can cause it to become unbalanced. The
ability of bearing damping system 70A, 70B, 70C, 70D, or 70E to
fine tune the pressure of fluid 74 in fluid compartment 66 however,
can account for balance changes in the rotation of the spool and
thus effectively dampen the vibrations.
Discussion of Possible Embodiments
[0073] The following are non-exclusive descriptions of possible
embodiments of the present invention.
[0074] A bearing damping system according to an exemplary
embodiment of the invention can optionally include, additionally
and/or alternatively, any one or more of the following features,
configurations and/or additional components: a pump configured to
pump a fluid through the system; a variable position valve
connected to the pump by a first conduit and having a plurality of
open positions each configured to generate different flows of the
fluid downstream from the variable position valve; and a bearing
assembly connected to the variable position valve by a second
conduit and including: a bearing housing having an outer surface
and an inner surface, the bearing housing configured to be attached
to a stationary structure; a stationary bearing race having an
outer surface and an inner surface and positioned within the
bearing housing; a rotating bearing race having an outer surface
and an inner surface spaced apart from the stationary bearing race
and configured to be attached to a rotating component; a bearing
element disposed between the inner surface of the stationary
bearing race and the outer surface of the rotating g bearing race;
and a fluid compartment defined by the space between the inner
surface of the bearing housing and the outer surface of the
stationary race and configured to receive the fluid from the second
conduit.
[0075] The bearing damping system of the preceding paragraph can
optionally include, additionally and/or alternatively, any one or
more of the following features, configurations and/or additional
components:
[0076] A further embodiment of the foregoing bearing damping
system, wherein the variable position valve comprises: a pressure
regulating valve that can have an adjustable diaphragm disposed
between the first conduit and the second conduit.
[0077] A further embodiment of the foregoing bearing damping
system, wherein the bearing system can include a plate movably
disposed within the variable position valve to generate a plurality
of flow areas through the variable position valve.
[0078] A further embodiment of the foregoing bearing damping
system, wherein the variable position valve can include a sleeve
disposed in the first conduit in which the sleeve can include a
plurality of orifices and a poppet movably disposed within the
sleeve and configured to regulate a flow area though the sleeve by
blocking at least one orifice.
[0079] A further embodiment of the foregoing bearing damping
system, wherein the variable position valve can be configured to
restrict a flow of the fluid into the fluid compartment when a
fluid supply pressure into the compartment exceeds a threshold
pressure.
[0080] A further embodiment of the foregoing bearing damping
system, wherein the variable position valve can be configured to
increase a flow of the fluid when the fluid supply pressure into
the fluid compartment falls below a threshold pressure.
[0081] A further embodiment of the foregoing bearing damping
system, wherein the system can further include a controller
configured to monitor a parameter and actuate the variable position
valve to maintain an optimum fluid pressure in the fluid
compartment, wherein the parameter monitored by the controller is
selected from the group consisting of: a stationary structure
vibration rate, a component rotation rate, a fluid pressure in the
first conduit, a fluid pressure in the second conduit, a fluid
pressure in the fluid compartment, a fluid viscosity in the first
conduit, a fluid viscosity in the second conduit, a fluid viscosity
in the fluid compartment, a fluid temperature in the fluid
compartment, a fluid temperature in the first conduit, a fluid
temperature in the second conduit, and combinations thereof.
[0082] A further embodiment of the foregoing bearing damping
system, wherein the system can further include an accelerometer
disposed on the stationary structure configured to measure the
stationary structure vibration rate.
[0083] A gas turbine engine according to an exemplary embodiment of
the invention can optionally include, additionally and/or
alternatively, any one or more of the following features,
configurations and/or additional components: a stationary section;
a rotating section joined to a shaft; a bearing housing having a
radially outer surface and a radially inner surface and attached to
the stationary section of the gas turbine engine; a stationary
bearing race having a radially outer surface and a radially inner
surface and spaced radially inward from the bearing housing; a
rotating bearing race having a radially outer surface and a
radially inner surface and spaced radially inward from the
stationary bearing race and attached to the shaft; a bearing
element disposed between the radially inner surface of the
stationary bearing race and the radially outer surface of the
rotating bearing race; a fluid compartment defined by the space
between the radially inner surface of the bearing housing and the
radially outer surface of the stationary race; a pump configured to
pump a fluid into the fluid compartment; and a variable position
valve having a plurality of open positions configured to generate a
plurality of fluid flows within the fluid compartment.
[0084] The gas turbine engine of the preceding paragraph can
optionally include, additionally and/or alternatively, any one or
more of the following features, configurations and/or additional
components:
[0085] A further embodiment of the foregoing gas turbine engine,
wherein the variable position valve can be positioned between the
pump and the fluid chamber.
[0086] A further embodiment of the foregoing gas turbine engine,
wherein the variable position valve can regulate a flow of the
fluid by increasing or decreasing a size of a valve flow area
[0087] A further embodiment of the foregoing gas turbine engine,
wherein the variable position can increase the size of the valve
flow area when the fluid supply pressure into the fluid compartment
falls below a threshold pressure.
[0088] A further embodiment of the foregoing gas turbine engine,
wherein the variable position valve can decrease the size of the
valve flow area when the fluid supply pressure into the fluid
compartment exceeds a threshold pressure.
[0089] A further embodiment of the foregoing gas turbine engine,
wherein the gas turbine engine can further include a controller
that actuates the variable position valve based on a parameter
selected from the group consisting of: a stationary structure
vibration rate, a shaft rotation rate, a fluid pressure between the
pump and the variable position valve, a fluid pressure between the
variable position pump and the fluid compartment, a fluid pressure
in the fluid compartment, a fluid viscosity, a fluid temperature,
and combinations thereof.
[0090] A further embodiment of the foregoing gas turbine engine,
wherein the stationary structure vibration rate can be measured by
an accelerometer.
[0091] A further embodiment of the foregoing gas turbine engine,
wherein the bearing element can be a ball or a roller.
[0092] A method of adjusting a stiffness of a fluid damped bearing
according to an exemplary embodiment of the invention can
optionally include, additionally and/or alternatively, any one or
more of the following steps: pumping a fluid through a variable
position valve having a plurality of open positions; sensing a
parameter relating to a vibration rate of a rotating component;
actuating a variable position valve in response to the sensed
parameter to control a flow of a fluid; and routing the fluid from
the variable position valve to a fluid compartment formed between a
bearing housing and a stationary race of the fluid damped
bearing.
[0093] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following steps or features:
[0094] A further embodiment of the foregoing method, wherein the
parameter can be selected from the group consisting of: a
stationary structure vibration rate, a component rate of rotation,
a fluid viscosity, a fluid temperature, a fluid pressure, and
combinations thereof.
[0095] A further embodiment of the foregoing method, wherein the
method can include the step of restricting a flow of the fluid into
the fluid damped bearing when the pressure inside the compartment
exceeds a threshold pressure.
[0096] A further embodiment of the foregoing method, wherein the
method can include the step of increasing the flow of the fluid
when the pressure falls below a threshold feed pressure.
[0097] 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.
* * * * *