U.S. patent application number 10/115387 was filed with the patent office on 2003-10-09 for tuned mass damper with translational axis damping.
Invention is credited to Boyd, James H., Davis, Toren S., Koehler, David R..
Application Number | 20030188941 10/115387 |
Document ID | / |
Family ID | 28673763 |
Filed Date | 2003-10-09 |
United States Patent
Application |
20030188941 |
Kind Code |
A1 |
Davis, Toren S. ; et
al. |
October 9, 2003 |
TUNED MASS DAMPER WITH TRANSLATIONAL AXIS DAMPING
Abstract
A tuned mass damper includes a container having first and second
inside wall portions, and a proof mass disposed within the
container. Multiple pairs of oppositely directed bellows containing
damping fluid are connected between the wall portions and the mass
to permit motion of the mass along primary axes. A spring is
connected in series with each pair of bellows. The spring has a
diameter substantially less than a diameter of the corresponding
pair of bellows so that the spring and bellows allow translational
movement of the mass about an axis other than the primary axes.
Inventors: |
Davis, Toren S.; (Peoria,
AZ) ; Koehler, David R.; (Glendale, AZ) ;
Boyd, James H.; (Phoenix, AZ) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.
101 COLUMBIA ROAD
P O BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Family ID: |
28673763 |
Appl. No.: |
10/115387 |
Filed: |
April 3, 2002 |
Current U.S.
Class: |
188/379 |
Current CPC
Class: |
F16F 7/10 20130101; F16F
15/02 20130101; F16F 7/104 20130101; F16F 13/00 20130101 |
Class at
Publication: |
188/379 |
International
Class: |
F16F 007/10 |
Claims
The invention claimed is:
1. A tuned mass damper comprising: a container having inner walls;
a mass disposed within the container; a first pair of oppositely
directed fluid containment assemblies each comprising a cup-shaped
member and an expandable bellows connected to the mass to define a
fluid chamber containing a damping fluid, the first pair of
oppositely directed fluid containment assemblies permitting motion
of the mass along a first axis; a second pair of oppositely
directed fluid containment assemblies each comprising a cup-shaped
member and an expandable bellows connected to the mass to define a
fluid chamber containing a damping fluid, the second pair of
oppositely directed fluid containment assemblies permitting motion
of the mass along a second axis; first and second springs connected
in series with the first pair of fluid containment assemblies for
biasing the first pair of containment assemblies between opposite
inner walls of the container, the first and second springs each
having an outside diameter less than an inside diameter of the
cup-shaped members to allow translational deflection of the mass
about an axis other than the first axis; and third and fourth
springs connected in series with the second pair of fluid
containment assemblies for biasing the second pair of containment
assemblies between opposite inner walls of the container, the third
and fourth springs each having an outside diameter less than an
inside diameter of the cup-shaped members to allow translational
deflection of the mass about an axis other than the second
axis.
2. The tuned mass damper as defined in claim 1, wherein each of the
first, second, third, and fourth springs each has an outer diameter
substantially less than the inside diameter of the cup-shaped
members.
3. The tuned mass damper as defined in claim 1, wherein each of the
first, second, third, and fourth springs are disposed within
recesses provided in the cup-shaped members.
4. The tuned mass damper as defined in claim 1, wherein the mass
has a first channel extending between the first pair of oppositely
directed fluid containment assemblies for allowing damping fluid to
pass between fluid chambers, and a second channel extending between
the second pair of oppositely directed fluid containment assemblies
for allowing damping fluid to pass between fluid chambers.
5. The tuned mass damper as defined in claim 1, wherein the
cup-shaped members each comprise a conical section.
6. The tuned mass damper as defined in claim 1 further comprising
an adjustable tuning screw connected to one of said springs to
allow adjustment of the spring constant.
7. The tuned mass damper as defined in claim 1, wherein the damper
is mounted on a spacecraft.
8. A tuned mass damper comprising: a container having first,
second, third, and fourth inner walls; a mass disposed within the
container; a first pair of oppositely directed fluid containment
assemblies each comprising a cup-shaped member and an expandable
bellows connected to the mass to define a fluid chamber containing
a damping fluid, the first pair of oppositely directed fluid
containment assemblies permitting motion of the mass along a first
axis; a second pair of oppositely directed fluid containment
assemblies each comprising a cup-shaped member and an expandable
bellows connected to the mass to define a fluid chamber containing
a damping fluid, the second pair of oppositely directed fluid
containment assemblies permitting motion of the mass along a second
axis; first and second springs connected in series with the first
pair of fluid containment assemblies for biasing the first pair of
containment assemblies between the first and second inner walls of
the container, the first and second springs each having an outside
diameter substantially less than an inside diameter of the
cup-shaped members to allow translational deflection of the mass
about an axis other than the first axis; and third and fourth
springs connected in series with the second pair of fluid
containment assemblies for biasing the second pair of containment
assemblies between the third and fourth inner walls of the
container, the third and fourth springs each having an outside
diameter substantially less than an inside diameter of the
cup-shaped members to allow translational deflection of the mass
about an axis other than the second axis.
9. The tuned mass damper as defined in claim 8, wherein the mass
has a first channel extending between the first pair of oppositely
directed fluid containment assemblies for allowing damping fluid to
pass between fluid chambers, and a second channel extending between
the second pair of oppositely directed fluid containment assemblies
for allowing damping fluid to pass between fluid chambers.
10. The tuned mass damper as defined in claim 8, wherein the
cup-shaped members each comprise a conical section.
11. The tuned mass damper as defined in claim 8 further comprising
an adjustable tuning screw connected to one of said springs to
allow adjustment of the spring constant.
12. The tuned mass damper as defined in claim 8, wherein the damper
is mounted on a spacecraft.
13. A tuned mass damper comprising: a container having first and
second inner walls; a mass disposed within the container; a first
fluid containment assembly comprising a first bellows and a first
cup-shaped member connected to the mass to define a first fluid
chamber containing a damping fluid; a second fluid containment
assembly comprising a second bellows and a second cup-shaped member
connected to the mass to define a second fluid chamber containing a
damping fluid, the first and second fluid containment assemblies
permitting motion of the mass along a first axis; and a first
spring connected in series between the first inner wall of the
container and the first cup-shaped member, said first spring having
an outer diameter less than an inner diameter of the first
cup-shaped member so that the first spring and first bellows allow
translational deflection of the mass about an axis other than the
first axis.
14. The tuned mass damper as defined in claim 13 further comprising
a second spring connected in series between the second inner wall
of the container and the second cup-shaped member, said second
spring having an outer diameter less than an inner diameter of the
second cup-shaped member so that the second spring and second
bellows allow translational deflection of the mass about an axis
other than the first axis.
15. The tuned mass damper as defined in claim 13, wherein the first
and second cup-shaped members each includes a conical section.
16. The tuned mass damper as defined in claim 13, wherein the mass
has a channel extending between the first and second fluid chambers
for allowing damping fluid to pass therethrough.
17. The tuned mass damper as defined in claim 13 further comprising
an adjustable tuning screw connected to the first spring to allow
adjustment of the spring constant.
18. The tuned mass damper as defined in claim 13, wherein the
damper is mounted on a spacecraft.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to damping devices
and, more particularly, relates to a tuned mass damper for damping
oscillations and vibrations which occur in structures, such as
those found on spacecraft satellites.
[0002] Certain types of structures oscillate when subjected to
vibratory excitations. Examples of vibration excitable structures
include reflectors, solar arrays, and booms for carrying equipment,
all of which are commonly found on spacecraft satellites which are
subjected to thermal shocks and other vibratory excitations that
may cause the structure to vibrate at a predetermined frequency.
Vibratory oscillations of these and other structures can cause
inaccuracy in equipment associated therewith and, thus, it is
desirable to damp vibrations in certain structures.
[0003] Conventional tuned mass dampers generally employs a spring
positioned proof mass mounted in a container of damping fluid. The
spring stiffness and the mass are chosen to have substantially the
same frequency of oscillation of the structure and damper device
combination so that, upon oscillation, the vibrating structure
provides an input to the damper. Due to the damper arrangement, the
mass vibrates one hundred eighty degrees (180.degree.) out of phase
with the vibrating structure. As a consequence, the tuned mass
damper essentially absorbs a substantial portion of the energy of
the vibrating structure and cancels the structure motion at the
predetermined frequency so that the tuned mass damper and structure
begin to vibrate at two slightly different off-resonant
frequencies. As a consequence of the resultant damping, the
displacement of the vibrating structure is substantially
reduced.
[0004] Many conventional tuned mass dampers employ a proof mass
that is limited to damping vibrations in a single axis. One
approach to providing multiple-axes damping is disclosed in U.S.
Pat. No. 5,775,472, entitled "MULTI-AXIS TUNED MASS DAMPER," the
disclosure of which is hereby incorporated herein by reference. The
aforementioned approach employs a single mass mounted for motion in
two or three axes and supported by springs chosen to provide a
frequency of vibration in each axis. In each orthogonal axis, a
pair of oppositely directed expandable bellows containing a damping
fluid are connected between wall portions of a generally
cylindrical cup-shaped housing and the mass to permit motion of the
mass along the designated axis. While multiple pairs of bellows and
springs are arranged to achieve damping in multiple orthogonal
axes, the spring and bellows design of the above-described tuned
mass damper offers limited translational movement of the mass.
[0005] It is therefore desirable to provide for a tuned mass damper
which permits large translational deflections of the proof mass. In
particular, it is desirable to provide for a multi-axes tuned mass
damper which allows extended movement of the mass in directions
transverse to the individual primary orthogonal damping axes.
SUMMARY OF THE INVENTION
[0006] The present invention provides for a multiple axes tuned
mass damper which permits extended transverse movement of a proof
mass. The tuned mass damper includes a container having inner walls
and a mass disposed within the container. The damper has a first
pair of oppositely directed fluid containment assemblies each
including a cup-shaped containment member and an expandable bellows
connected to the mass to define a fluid chamber containing a
damping fluid. The first pair of oppositely directed fluid
containment assemblies permit motion of the mass along a first
axis. The damper also has a second pair of oppositely directed
fluid containment assemblies each including a cup-shaped
containment member and an expandable bellows connected to the mass
to define a fluid chamber containing a damping fluid. The second
pair of oppositely directed fluid containment assemblies permits
motion of the mass along a second axis. First and second springs
bias the first pair of fluid containment assemblies between
opposite inner walls of the container. The first and second springs
each have an outside diameter less than an inside diameter of the
cup-shaped containment members to allow translational deflection of
the mass about an axis other than the first axis. Third and fourth
springs bias the second pair of fluid containment assemblies
between opposite inner walls of the container. The third and fourth
springs each have an outside diameter less than an inside diameter
of the cup-shaped containment members to allow translational
deflection of the mass about an axis other than the second
axis.
[0007] These and other features, advantages and objects of the
present invention will be further understood and appreciated by
those skilled in the art by reference to the following
specification, claims and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In the drawings:
[0009] FIG. 1 is a perspective view of a three-axis tuned mass
damper mounted on a spacecraft boom according to the present
invention;
[0010] FIG. 2 is a cross-sectional view of the tuned mass damper
shown in FIG. 1 taken through the X-Y plane;
[0011] FIG. 3 is an enlarged view of section III of FIG. 2; and
[0012] FIG. 4 is an alternative cross-sectional view of section III
of FIG. 2 showing the addition of an adjustable tuning screw for
adjusting the stiffness of the spring.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to FIGS. 1 and 2, a three-axes tuned mass damper
is generally shown designated by reference numeral 10. The tuned
mass damper 10 is shown mounted to a structure, such as a large
boom assembly 12 on a satellite spacecraft. The spacecraft boom
assembly 12 may tend to oscillate when subjected to shock or other
vibratory excitations. The tuned mass damper 10 is mounted to the
boom assembly 12 and oriented to damp a substantial portion of the
energy of the boom assembly 12 to thereby reduce the vibratory
motion of the boom assembly 12.
[0014] The tuned mass damper 10 includes a generally cubical
housing 14 having six outwardly protruding caps 20a-20f provided in
each of the six respective side walls. The housing 14 may
alternately be configured in various other shapes. Each of caps
20a-20f covers the end portion of one of six corresponding
spring-biased fluid containment assemblies having expandable
bellows and cup-shaped containment members which are spring-biased
against inner walls of the cups 20a-20f and oriented to provide
vibration damping about three primary axes, namely the orthogonal
X-axis, Y-axis, and Z-axis. Also shown positioned on top of the
tuned mass damper 10 are a pair of Frangibolt.TM. or equivalent
launch locks 16 and 18 which may be used to rigidly support the
tuned mass damper proof mass 50 during spacecraft launch.
[0015] The tuned mass damper 10 is shown in FIG. 2 taken through a
central cross section along the X-Y plane. The tuned mass damper 10
includes a movable proof mass 50 suspended substantially centrally
within housing 14. Proof mass 50 is an inertial mass that may
include Tungsten, for example. A first pair of spring-biased
cup-shaped fluid containment members 22a and 22b each having a
conical section are located on opposite sides of mass 50 aligned in
the X-axis. A second pair of spring-biased cup-shaped fluid
containment members 22c and 22d each having a conical section are
aligned in the Y-axis, and positioned on opposite sides of the
proof mass 50. Fluid containment members 22a and 22b are sealingly
connected to the mass 50 by way of expandable bellows 24a and 24b
which together form damping fluid chambers 32a and 32b,
respectively. Likewise, fluid containment members 22c and 22d are
sealingly connected to proof mass 50 by way of expandable bellows
24c and 24d to form damping fluid chambers 32c and 32d,
respectively. It should be appreciated that the tuned mass damper
10 further includes a third pair of spring-biased cup-shaped fluid
containment members (not shown) each having a conical section and
disposed on opposite sides of proof mass 50 and aligned in the
Z-axis for providing damping about the Z-axis.
[0016] The cup-shaped fluid containment members 22a-22d each have a
conical section extending outward to a lip 23 spaced at a
predetermined distance from the interior wall of housing 14. The
fluid chambers 32a-32d defined by the fluid containment members
22a-22d, bellows 24a-24d, and mass 50 contain damping fluid. The
expandable bellows 24a-24d expand and contract to allow the
cup-shaped fluid containment members 22a-22d to translate along the
primary X-axis and Y-axis. The fluid chambers 32a-32d are filled
with a damping fluid that is selected based on the damping
frequency characteristics. Proof mass 50 has three individual
passages 60a, 60b, and 60c extending therethrough. Passage 60a
allows damping fluid to flow between fluid chambers 32a and 32b.
Passage 60b allows damping fluid to flow between fluid chambers 32c
and 32d. Passage 60c allows fluid to flow between the remaining two
fluid chambers (not shown) aligned in the Z-axis.
[0017] Springs 26a-26d are shown as helical coil springs connected
at opposite ends to connectors, including outer connectors 30a-30d
and inner connectors 28a-28d, respectively. Outer connectors
30a-30d abut against the inner walls of the outer caps 20a-20d,
respectively. The inner connectors 28a-28d are fixed in place to
the respective cup-shaped fluid containment members 22a-22d. The
springs 26a-26d are centrally located within the conical section
opening in the cup-shaped containment members 22a-22d and are
spaced from the inner walls of members 22a-22d. Thus, the springs
26a-26d and containment members 22a-22d are configured to allow
substantial transverse movement of the fluid containment members
22a-22d such that the mass 50 is able to move extensively in
multiple directions.
[0018] Referring to FIG. 3, an enlarged portion of the tuned mass
damper 10 is further illustrated which further shows one of the
fluid containment assemblies including spring-biased cup-shaped
fluid containment member 22d and expandable bellows 24d connected
to proof mass 50 to define the damping fluid chamber 32d. The
helical coil spring 26d has an outside diameter D.sub.s
substantially smaller than the inside diameter D.sub.c of the
cup-shaped fluid containment member 22d taken at lip 23d. By
placing the spring 25d inside the central conical section of
cup-shaped containment member 22d and spacing the spring 26d a
sufficient distance from member 22d, the spring 26d is allowed to
bend sideways without interference with containment member 22d so
that member 22d can move transversely. As the mass 50 moves in the
horizontal direction about the X-axis, the vertical bellows 24c and
24d are distorted to the left and right and spring 26d bends so as
to allow for large transverse movement of the cup-shaped
containment member 22d without interference from spring 26d.
[0019] By configuring the bias spring 26d with an outer diameter
D.sub.s substantially less than the inside diameter D.sub.c of the
containment member 22d, the spring-biased containment member 22d is
allowed to move a substantial distance transverse to the primary
Y-axis. During transverse movement, the spring 26d bends laterally,
while the expandable bellows 24d expands and deforms laterally to
allow for the transverse motion. The amount of transverse movement
may be selected as a function of the lateral stiffness of the
spring 26d, effective length of the spring 26d, and lateral
stiffness of the expandable bellows 24d. Thus, the tuned mass
damper 10 of the present invention advantageously provides for
damping while allowing extended movement transverse to the primary
X-axis and Y-axis.
[0020] The tuned mass damper 10 is configured to damp oscillations
primarily at predetermined frequencies. According to one
embodiment, tuned mass damper 10 may be configured to provide
different predetermined frequency responses along each of the
X-axis, Y-axis, and Z-axis. Alternatively, the frequency response
in two or all three of the X-axis, Y-axis, and Z-axis may be
identical. It should be appreciated that in order to tune the tuned
mass damper 10 to a predetermined frequency, the mass 50, length
and stiffness of bias springs 26a-26d, stiffness of the expandable
bellows 24a-24d, and damping fluids are chosen to achieve the
predetermined frequency. Additionally, the lateral stiffness of the
expandable bellows 24a-24d and springs 26a-26d that move in the
transverse direction should also be taken into consideration. While
the tuned mass damper 10 is shown in FIG. 2 and described in
connection with two orthogonal pairs of spring-biased fluid
containment assemblies for damping vibrations in two orthogonal
axes, it should be appreciated that the present invention applies
to both two-axes and three-axes damping.
[0021] The tuned mass damper 10 may further be configured to
include an adjustable tuning screw 70 as shown in FIG. 4, according
to another embodiment. The adjustable tuning screw 70 is threaded
to include a helical channel 72 for engaging the inner surface of
spring 26d. The effective length of spring 26d can be varied by
turning screw 70 via screw head 74 to move the turning screw 70
inward or outward. In effect, the effective length of the spring
26d extends the distance from the end of the tuning screw 70 to
inner connector 28d. This enables the frequency response of the
tuned mass damper 10 to be adjusted simply by turning the
adjustable tuning screw 70 coupled to the cup-shaped fluid
containment member 22d to adjust the number of turns of spring 26d
that provide bias. Once the tuned mass damper 10 has been tuned and
mounted on the desired structure, such as a boom on a spacecraft,
vibrations of the structure in the X-axis, Y-axis, and Z-axis
direction will be countered by one hundred eighty degrees
(180.degree.) out of phase motion of the mass 50, thus extracting
energy from the boom motion and causing the boom and damper 10 to
oscillate at two slightly different frequencies. Since the tuned
mass damper 10 has absorbed a substantial portion of the energy,
the boom displacement becomes much smaller and effectively is
damped out by the damping fluid.
[0022] Accordingly, the tuned mass damper 10 of the present
invention provides for a multiple axes damper which effectively
damps vibrations of the structure to which it is attached along the
primary axes and further allows for extended transverse movement of
the mass 50 and fluid containment assemblies. The tuned mass damper
10 allows for transverse motion of the expandable bellows 24a-24d
and proof mass 50 such that the motion is not limited severely by
the arrangement of the spring-biased fluid containment members and
bellows. It should be appreciated that the present invention allows
for damping of vibrations about at least two or more axes.
[0023] It will be understood by those who practice the invention
and those skilled in the art, that various modifications and
improvements may be made to the invention without departing from
the spirit of the disclosed concept. The scope of protection
afforded is to be determined by the claims and by the breadth of
interpretation allowed by law.
* * * * *