U.S. patent application number 09/351508 was filed with the patent office on 2002-06-27 for speed-adaptive dynamic-vibration absorber.
Invention is credited to BOCKING, JORG, ECKEL, HANS-GERD, OBERLE, RAINER.
Application Number | 20020078791 09/351508 |
Document ID | / |
Family ID | 7873764 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020078791 |
Kind Code |
A1 |
ECKEL, HANS-GERD ; et
al. |
June 27, 2002 |
SPEED-ADAPTIVE DYNAMIC-VIBRATION ABSORBER
Abstract
A speed-adaptive dynamic-vibration absorber for a shaft
rotatable about an axis, including a hub part on which at least one
inertial mass is provided. The at least one inertial mass, starting
from a middle position in which its center of gravity is the
greatest distance from the axis, is moveable back and forth
relative to the hub part along a path of motion in deflection
positions in which the distance of the center of gravity of the at
least one inertial mass changes with respect to the middle
position, the path of motion having a radius of curvature which
changes at least section-by-section with increasing deflection of
the inertial mass out of the middle position.
Inventors: |
ECKEL, HANS-GERD;
(LAUDENBACH, DE) ; OBERLE, RAINER; (HIRSCHBERG,
DE) ; BOCKING, JORG; (DARMSTADT, DE) |
Correspondence
Address: |
KENYON & KENYON
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
7873764 |
Appl. No.: |
09/351508 |
Filed: |
July 12, 1999 |
Current U.S.
Class: |
74/574.4 |
Current CPC
Class: |
Y10T 74/2131 20150115;
F16F 15/145 20130101 |
Class at
Publication: |
74/574 |
International
Class: |
F16F 015/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 1998 |
DE |
198 31 160.5 |
Claims
What is claimed is:
1. A speed-adaptive dynamic-vibration absorber for a shaft
rotatable about an axis, comprising: at least one inertial mass;
and a hub part with which the at least one inertial mass is movably
connected, the at least one inertial mass, having a middle position
in which the distance between the center of gravity of the inertial
mass and the axis is at a maximum, the inertial mass being moveable
back and forth relative to the hub part along a path of motion in
deflection positions in which the distance of the center of gravity
of the at least one inertial mass changes with respect to the
middle position; wherein the path of motion has a radius of
curvature which changes at least sectionally with increasing
deflection of the inertial mass from the middle position.
2. The speed-adaptive dynamic-vibration absorber as recited in
claim 1, wherein radius of curvature decreases at least sectionally
with increasing deflection of the inertial mass out of the middle
position.
3. The speed-adaptive dynamic-vibration absorber as recited in
claim 2, wherein the radius of curvature decreases
continuously.
4. The speed-adaptive dynamic-vibration absorber as recited in
claim 1, further comprising a plurality of inertial masses
circumferentially arrayed about the axis.
5. The speed-adaptive dynamic-vibration absorber as recited in
claim 2, further comprising a plurality of inertial masses
circumferentially arrayed about the axis.
6. The speed-adaptive dynamic-vibration absorber as recited in
claim 3, further comprising a plurality of inertial masses
circumferentially arrayed about the axis.
7. The speed-adaptive dynamic-vibration absorber as recited in
claim 4, wherein circumferentially adjacent inertial masses are
rounded off at ends facing one another, and are loosely in contact
with one another, regardless of the deflection.
8. The speed-adaptive dynamic-vibration absorber as recited in
claim 1, wherein the radius of curvature of the path of motion in
the middle position is determined by the formula 14 R = k L x 2 ,L
being the distance of curvature midpoint from the axis, x being the
order of the exciting vibration and k being a factor in the range
from 0.8 to 1.2.
9. The speed-adaptive dynamic-vibration absorber as recited in
claim 2, wherein the radius of curvature (R) of the path of motion
(B) in the middle position is determined by the formula 15 R = k L
x 2 ,where L is the distance of curvature midpoint (M) from the
axis, x is the order of the exciting vibration and k is a factor in
the range from 0.8 to 1.2.
10. The speed-adaptive dynamic-vibration absorber as recited in
claim 4, wherein the radius of curvature (R) of the path of motion
in the middle position is determined by the formula 16 R = k L x 2
,where L is the distance of curvature midpoint from the axis, x is
the order of the exciting vibration and k is a factor in the range
from 0.8 to 1.2.
11. The speed-adaptive dynamic-vibration absorber as recited in
claim 8, wherein k lies in the range from 0.8 to 0.999 or 1.001 to
1.2.
12. The speed-adaptive dynamic-vibration absorber as recited in
claim 8, wherein the path of motion has the shape of a cycloid
section.
13. The speed-adaptive dynamic-vibration absorber as recited in
claim 11, wherein the path of motion has the shape of a cycloid
section.
14. The speed-adaptive dynamic-vibration absorber as recited in
claim 8, wherein the path of motion lies in a field which is
bounded on the one hand by a circle whose radius of curvature (R)
is determined by the formula 17 R = k L x 2 ,where k=1.2, and on
the other hand by a cycloid (Z) whose radius of curvature (R) in
the middle position is determined by the formula 18 R = k L x 2
,where k=0.8.
15. The speed-adaptive dynamic-vibration absorber as recited in
claim 11, wherein the path of motion lies in a field which is
bounded on the one hand by a circle whose radius of curvature (R)
is determined by the formula 19 R = k L x 2 ,where k=1.2, and on
the other hand by a cycloid (Z) whose radius of curvature (R) in
the middle position is determined by the formula 20 R = k L x 2
,where k=0.8.
16. The speed-adaptive dynamic-vibration absorber as recited in
claim 11, wherein the path of motion lies in a field which is
bounded on the one hand by a circle whose radius of curvature (R)
is determined by the formula 21 R = k L x 2 ,where k=1.2, and on
the other hand by a cycloid (Z) whose radius of curvature (R) in
the middle position is determined by the formula 22 R = k L x 2
,where k=0.8.
17. The speed-adaptive dynamic-vibration absorber as recited in
claim 13, wherein the path of motion in a first section adjacent to
the middle position lies in a first region of the field, the first
region being bounded on one hand by a circle whose radius of
curvature (R) is determined by the formula 23 R = k L x 2 ,where
k=1.0, and on the other hand by the circle (K) whose radius of
curvature (R) is determined by the formula 24 R = k L x 2 ,where
k=1.2.
18. The speed-adaptive dynamic-vibration absorber as recited in
claim 17, wherein the path of motion in a second section, which is
adjacent to the first section, lies in a second region of the
field, the second region being bounded on one hand by the circle
whose radius of curvature (R) is determined by the formula 25 R = k
L x 2 ,where k=1.0, and on the other hand by the cycloid (Z) whose
radius of curvature (R) in the middle position is determined by the
formula 26 R = k L x 2 ,where k=0.8.
19. The speed-adaptive dynamic-vibration absorber as recited in
claim 1, wherein the at least one inertial mass is supported in the
hub part by axially parallel bolts that are rotatable about a bolt
axis, the bolts being allocated to first rolling paths of the hub
part and second rolling paths of the inertial mass.
20. The speed-adaptive dynamic-vibration absorber as recited in
claim 4, wherein the at least one inertial mass is supported in the
hub part by axially parallel bolts that are rotatable about a bolt
axis, the bolts being allocated to first rolling paths of the hub
part and second rolling paths of the inertial mass.
21. The speed-adaptive dynamic-vibration absorber as recited in
claim 8, wherein the at least one inertial mass is supported in the
hub part by axially parallel bolts that are rotatable about a bolt
axis, the bolts being allocated to first rolling paths of the hub
part and second rolling paths of the inertial mass.
22. The speed-adaptive dynamic-vibration absorber as recited in
claim 20, wherein a point (P) exists, allocated to the inertial
mass, which shifts with the inertial mass along the path of motion,
and whose distance in the middle position of the inertial mass is
twice as great from the curvature midpoint, allocated to the middle
position, of the path of motion of the point (P) as the distance of
the point (P) from the bolt axis, and that the first and second
rolling paths are designed in such a way that, in each deflection
position, the bolt axis is located on the geometric center of an
imaginary connecting line between the curvature midpoint, allocated
to the middle position, and each point of the path of motion of the
point (P).
Description
FIELD OF THE INVENTION
[0001] The invention relates to a speed-adaptive dynamic-vibration
absorber for a shaft rotatable about an axis, including a hub part
on which at least one inertial mass is provided. The inertial mass,
starting from a middle position in the distance from its center of
gravity to the axis is at a maximum, is moveable back and forth
relative to the hub part along a path of motion in deflection
positions such that the distance of the center of gravity of the at
least one inertial mass changes with respect to the middle
position.
BACKGROUND OF THE INVENTION
[0002] Such a speed-adaptive dynamic-vibration absorber is
described in the German Patent 196 31 989 C1.
[0003] At shafts of periodically operating machines, e.g., at the
crank shaft of an internal combustion engine, torsional vibrations
occur which are superimposed on the rotational motion, the
frequency of, the torsional vibrations changing with the rotational
speed of the shaft. To reduce these torsional vibrations,
dynamic-vibration absorbers can be provided. They are described as
speed-adaptive when they can cancel torsional vibrations over a
larger speed range, ideally over the entire speed range of the
machine. The principle underlying torsional vibration cancellers is
that, due to centrifugal force, the inertial masses endeavor to
circle the axis at the greatest distance possible when a rotary
motion is initiated. Torsional vibrations which are superimposed on
the rotary motion lead to a pendulum-like relative movement of the
inertial masses. The dynamic-vibration absorber has a natural
frequency f.sub.absorber proportional to the rotational speed, so
that torsional vibrations having frequencies which are proportional
in the same manner to the shaft rotational speed n (in revolutions
per second), can be canceled over a large speed range. Expressed
mathematically, f.sub.absorber=x*n where x is the order of the
exciting vibration. For example, in the case of a four-cylinder
four-stroke engine, this has the value x=2. In the known
dynamic-vibration absorber, the inertial masses move relative to
the hub part in a purely translatory manner on circular paths of
motion. However, the known speed-adaptive dynamic-vibration
absorber has the disadvantage that it is still not possible to
achieve optimum canceling effectiveness over the entire speed range
and load range.
SUMMARY OF THE INVENTION
[0004] The object of the present invention is to attain improved
canceling effectiveness over a wide speed range and load range.
[0005] This objective is achieved in a speed-adaptive
dynamic-vibration absorber of the type indicated above, in that the
path of motion has a radius of curvature which changes at least
section-by-section with increasing deflection of the inertial mass
out of the middle position.
[0006] This design according to the invention permits improved
canceling effectiveness. At the same time, the speed-adaptive
dynamic-vibration absorber can be better adapted to the torsional
vibrations to be canceled. The teaching of the present invention
opens up a great, previously unknown leeway in the design of the
dynamic-vibration absorber, permitting considerable improvement in
absorbing dynamic vibrations.
[0007] Particularly effective absorption of dynamic vibrations is
achieved, in that the radius of curvature decreases at least
section-by-section with increasing deflection of the inertial mass
out of the middle position.
[0008] According to one particularly advantageous refinement, the
radius of curvature decreases continuously. In this manner, the
path of motion receives a curvature which can be represented by a
strictly monotonically increasing function.
[0009] Particularly effective dynamic-vibration absorption is also
attained by providing a plurality of inertial masses adjacent in
the circumferential direction.
[0010] Particularly large inertial masses can be provided on a
small installation space if the inertial masses, adjacent in the
circumferential direction, are rounded off at the ends facing one
another, and are loosely in contact with one another, regardless of
the deflection.
[0011] Further improvement is achieved, in that the radius of
curvature of the path of motion in the middle position is
determined by the formula 1 R = k L x 2 ,
[0012] where L is the distance of the curvature midpoint from the
axis, x is the order of the exciting vibration and k is a factor in
the range from 0.8 to 1.2. In this context, the curvature midpoint
represents the point of rotation of the inertial mass. The order x
of the exciting vibration indicates the relationship between the
vibrational frequency and the rotational speed (in revolutions per
second). For example, in the case of a four-cylinder, four-stroke
engine, x=2 is for the dominantly exciting firing order. Optimized
vibrational damping can be achieved under the most varied
conditions by varying k in the indicated range.
[0013] Advantageously, k lies in the range from 0.8 to 0.999 or
1.001 to 1.2.
[0014] Vibrational damping can be further improved by providing the
path of motion with the shape of a cycloid section. A cycloid is a
curve which develops when a circle rolls along on a straight line.
A point fixedly joined to the circle at a distance from its
midpoint describes a curve, composed of congruent pieces, as the
circle rolls along on the straight line.
[0015] The tuneability of the dynamic-vibration absorber is further
improved, in that the path of motion lies in a field which is
bounded on the one hand by a circle whose radius of curvature is
determined by the formula 2 R = k L x 2 ,
[0016] where k=1.2, and on the other hand by a cycloid whose radius
of curvature in the middle position is determined by the formula 3
R = k L x 2 ,
[0017] where k=0.8.
[0018] In this context, the circle and the cycloid are arranged in
such a way that their paths coincide in the middle position. Good
dynamic-vibration absorption can be attained by this arrangement of
the paths of motion of the inertial masses located in a centrifugal
force field. In this manner, it is possible to achieve a
deflection-independent duration of the pendulum swing of the
inertial masses that are moveable relative to the hub part. Thus,
for example, in addition to the non-linearity of the swinging
inertial masses, hydrostatic and hydrodynamic effects resulting
from a lubricant can also be largely compensated.
[0019] In addition, the path of motion in a first section adjacent
to the middle position can lie in a first region of the field, the
first region being bounded on one hand by a circle whose radius of
curvature is determined by the formula 4 R = k L x 2 ,
[0020] where k=1.0, and on the other hand by the circle whose
radius of curvature is determined by the formula 5 R = k L x 2
,
[0021] where k=1.2. At the same time, the circles are arranged in
such a way that their paths coincide in the middle position.
[0022] According to a further aspect of this inventive idea, the
path of motion in a second section, which is adjacent to the first
section, lies in a second region of the field, the second region
being bounded on one hand by the circle whose radius of curvature
is determined by the formula 6 R = k L x 2 ,
[0023] where k=1.0, and on the other hand by the cycloid whose
radius of curvature in the middle position is determined by the
formula 7 R = k L x 2 ,
[0024] where k=0.8. The circle and the cycloid are arranged in such
a way that their paths coincide in the middle position. This design
of the path of motion, which is different region-by-region, opens
up new possibilities for further optimizing the damping under the
most varied conditions.
[0025] According to one advantageous refinement of the invention,
the at least one inertial mass is supported in the hub part by
axially parallel bolts that are rotatable about a bolt axis, the
bolts being allocated to first rolling paths (i.e., rolling curves)
of the hub part and second rolling paths of the inertial mass.
[0026] In a further embodiment based on this invention, given an
identical formation of the rolling paths of the inertial mass and
the hub part, a point exists, allocated to the inertial mass, which
shifts with the inertial mass along the path of motion, and whose
distance in the middle position of the inertial mass is twice as
great from the curvature midpoint, allocated to the middle
position, of the path of motion of the point as the distance of the
point from the bolt axis. The first and second rolling paths are
designed in such a way that, in each deflection position, the bolt
axis is located on the geometric center of an imaginary connecting
line between the curvature midpoint, allocated to the middle
position, and each point of the path of motion of the point. By
this means, it is specified how the rolling paths upon which the
bolts roll are to be constructed in order to achieve good
vibrational damping.
BRIEF DESCRIPTION OF THE DRAWING
[0027] FIG. 1: is a front view of a speed-adaptive
dynamic-vibration absorber constructed according to the principles
of the invention;
[0028] FIG. 2: is a cross-sectional view taken through a
speed-adaptive dynamic-vibration absorber;
[0029] FIG. 3: is a schematic representation of the paths of motion
executed by elements of the invention in the course of
operation;
[0030] FIG. 4: illustrates an inertial mass according to the
present invention;
[0031] FIG. 5: shows an enlarged segment of the inertial mass from
FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIG. 1 shows a speed-adaptive dynamic-vibration absorber for
a shaft (not shown) rotatable about an axis 1, the
dynamic-vibration absorber having a hub part 2 and a number of
inertial masses 3 adjacent in the circumferential direction. For
each inertial mass 3, hub part 2 has in each case two mounting
supports 4 adjacent in the circumferential direction to support
inertial masses 3 on hub part 2.
[0033] Each mounting support 4 is formed by an opening 5 in hub
part 2 and a bolt 6 accommodated therein. Bolt 6, whose
longitudinal axis runs parallel to axis 1 of hub part 2, extends
into an opening 7 formed in particular as a cut-out in inertial
mass 3.
[0034] Hub part 2 has a rolling path 8 bordering opening 5, and
inertial mass 3 has a rolling path 9 bordering opening 5. Rolling
paths 8, 9 and bolt 6 are formed and arranged in such a way that
inertial mass 3, starting from a middle position in which the
distance of its center of gravity to the axis 1 is at a maximum, is
moveable back and forth relative to hub part 2 along a path of
motion B in deflection positions. During such a pendulum motion of
inertial masses 3 taking place in the centrifugal force field, the
center of gravity of inertial masses 3 in the deflection positions
approaches axis 1. During a movement of inertial masses 3 between
the deflection positions, bolts 6 hob on rolling paths 8, 9 which
are inversely curved. Rolling path 8 in the hub part points in the
direction of axis 1, while rolling path 9 in inertial mass 3 points
outwardly away from axis 1.
[0035] In response to a torsional vibration superimposed on a
rotational motion, inertial masses 3 are moved from their mid
position, shown in FIG. 1, relative to hub part 2 along curved path
of motion B. In so doing, each inertial mass 3 carries out a
translatory movement relative to hub part 2, so that each point of
rigid inertial mass 3, particularly its center of gravity, shifts
along an identical path of motion B.
[0036] In addition, in openings 7, inertial masses 3 have guideways
10 lying opposite rolling paths 9, so that openings 7 assume the
shape of a U which is directed away from axis 1. Corresponding
guideways 11 are formed in mounting support 4 of hub part 2, as
well (shown in phantom in FIG. 1).
[0037] The circumferentially adjacent inertial masses are rounded
off at the ends facing one another, and loosely contact one another
independently of the deflection.
[0038] The cross-section along axis 1 shown in FIG. 2 further
elucidates the arrangement and mounting of inertial masses 3 on hub
part 2. In the specific embodiment shown in FIG. 2, inertial masses
3 are adjacently arranged in pairs axially on both sides of hub
part 2.
[0039] Rolling paths 8, 9 are components of inserts 12, 13 which
are undetachably accommodated in openings 5 and 7 of hub part 2 and
inertial mass 3, respectively. Inserts 12, 13 can also be loosely
inserted into openings 5 and 7 at first, and be bonded at openings
5 and 7 and inserts 12 and 13, respectively by subsequent molding
of layer 14, 15 bearing guideways 10, 11.
[0040] The section of hub part 2 having mounting supports 4 is
enclosed by caps 16 that are sealed off with respect to hub part 2,
so that a chamber 17 is formed. This is filled to a small extent
with a lubricant. Lubricating liquids such as lubricating oils or
lubricating grease can be considered as lubricants.
[0041] FIGS. 3, 4 and 5 schematically clarify more precisely the
formation of path of motion B according to the invention. Path of
motion B of a point P of inertial mass 3 has a radius of curvature
R in the middle position of inertial mass 3. Radius of curvature R
of path of motion B in the middle position is determined by the
formula R=k L/x.sup.2, L being the distance of curvature midpoint M
from axis 1, x being the order of the exciting vibration and k
being a factor in the range from 0.8 to 1.2. In this context, k is
preferably different from 1.
[0042] The radius of curvature changes with increasing deflection
of inertial mass 3 out of the middle position into the deflection
position and, in so doing, decreases (radius of curvature R').
Consequently, the curvature of path of motion B increases. The
curvature increases continuously and can be described by a
monotonic function. Path of motion B can have the shape of a
cycloid section Z. A cycloid is a curve which develops when a
circle rolls along on a straight line. A point fixedly joined to
the circle at a distance from its middle point describes a curve,
composed of congruent pieces, as the circle rolls off on the
straight line. The formation of the paths of motion of the inertial
masses according to the present invention permits a particularly
good tuneability of the dynamic-vibration absorber.
[0043] Furthermore, path of motion B lies in the region of a field
F which, on one hand, is bounded by a circle K whose radius of
curvature R is determined by the formula 8 R = k L x 2 ,
[0044] where k=1.2, and on the other hand by a cycloid Z whose
radius of curvature R in the middle position is determined by the
formula 9 R = k L x 2 ,
[0045] where k=0.8. At the same time, the circle and the cycloid
are arranged in such a way that their paths coincide in the middle
position, and the initial curvature of cycloid Z corresponds to the
curvature of a circular path K, where k=0.8.
[0046] The damping action is further improved, in that path of
motion B in a first section, adjacent to the middle position, lies
in a first region of field F, the first region being bounded on one
hand by a circle whose radius of curvature is determined by the
formula 10 R = k L x 2 ,
[0047] where k=1.0, and on the other hand by circle K whose radius
of curvature is determined by the formula 11 R = k L x 2 ,
[0048] where k=1.2. The circles are arranged in such a way that
their paths coincide in the middle position. In a second section
which is contiguous to the first section, path of motion B then
runs in a second region of field F, the second region being bounded
on one hand by the circle whose radius of curvature is determined
by the formula 12 R = k L x 2 ,
[0049] where k=1.0, and on the other hand by cycloid Z whose radius
of curvature R in the middle position is determined by the formula
13 R = k L x 2 ,
[0050] where k=0.8. The circle and cycloid Z are arranged, such
that their paths coincide in the middle position (the circle
dividing field F into two regions is not shown in FIG. 3). The
formation of the path of motion, differing section-by-section,
opens up new possibilities for further optimizing the damping
action under the most varied conditions.
[0051] Inertial mass 3 executes a purely translatory movement
relative to hub part 2. This is achieved by supporting each
inertial mass 3 in axially parallel bolts 6, such a support also
being described as a parallel bifilar or double suspension. Since,
in addition, inertial mass 3 is a rigid body, each point P
allocated to inertial mass 3 performs an identical movement along
path of motion B running through the respective point P.
[0052] Rolling paths 8, 9 of the hub part and of inertial mass 3
are constructed as follows. Beginning from a point P--which is
allocated to inertial mass 3, shifts with inertial mass 3 along
path of motion B and whose distance in the middle position of
inertial mass 3 is twice as great from curvature midpoint M,
allocated to the middle position, of the path of motion of point P
as the distance of point P from axis 20 of bolt 6. First and second
rolling paths 8, 9 are designed such that, in each deflection
position, bolt axis 20 is located on the geometric center of an
imaginary connecting line V between curvature midpoint M allocated
to the middle position, and each point of path of motion B of point
P. The spatial design of first and second rolling paths 8, 9 can be
derived from this position of bolt axis 20, the rolling paths in
each case being set apart from bolt axis 20 by bolt radius r.
* * * * *