Apparatus for damping fluctuations of torque

A composite flywheel wherein a primary mass is rotatable by the engine of a motor vehicle and can transmit torque to a secondary mass--which serves to rotate the clutch plate of a friction clutch--by way of several sets of coil springs and a planetary transmission. A friction clutch serves to oppose certain angular movements of the primary and secondary masses relative to each other, and a slip clutch is provided to limit the magnitude of the torque which can be transmitted by the planetary transmission.

BACKGROUND OF THE INVENTION 
The invention relates to apparatus for damping the fluctuations (such as 
vibrations and/or peaks) of torque which is being transmitted between a 
plurality of rotary masses, for example, in a composite flywheel wherein a 
first or primary mass or flywheel is rotatable with as well as relative to 
a second or secondary mass or flywheel, or vice versa. 
More particularly, the invention relates to improvements in apparatus which 
can be utilized with advantage to oppose undesirable stray movements (such 
as vibratory movements, abrupt accelerations or abrupt decelerations) of 
one or more parts which receive torque from a crankshaft, a camshaft or 
another rotary output element of a prime mover (such as the combustion 
engine of a motor vehicle) and which serve to transmit torque to an input 
element (such as the pressure plate or the clutch disc of a friction 
clutch) which, in turn, transmits torque to one or more rotary input 
elements of one or more driven assemblies (e.g., a manual, automated or 
automatic change-speed transmission, a differential, a light generator, an 
air conditioning system, a constituent of a power steering mechanism 
and/or others). 
It is well known to provide the power train of a motor vehicle with a 
vibration damping system which is called a composite flywheel and employs 
two coaxial masses or flywheels (including a primary mass which is 
attached to the output element of the engine and a secondary mass which 
can transmit torque to a transmission, e.g., by way of a suitable clutch) 
which are rotatable with each other as well as relative to each other 
against the resistance of a damping device or other suitable means for 
yieldably opposing rotation of the primary and secondary masses relative 
to each other. 
It is also known to employ a damping mechanism which includes a planetary 
transmission (hereinafter called planetary for short) and energy storing 
means acting in the circumferential direction of the primary and secondary 
masses. An advantage of a planetary between the primary and secondary 
masses of a torsional vibration damping apparatus (as used herein, the 
term "torsional vibration" is intended to embrace all undesirable stray 
movements which should not be transmitted from the primary to the 
secondary mass of a composite flywheel or an analogous vibration damping 
apparatus or system, e.g., in the power train between the engine and the 
wheels of a motor vehicle, such as might be caused for example by inertia, 
inaccurate centering and/or for other reasons) is that the planetary can 
eliminate or weaken the influence of fluctuations of torque resulting from 
the inertia of rotating masses and/or from the damping of transmitted 
torque. Otherwise stated, the planetary can exert a beneficial influence 
upon the behavior of a torsional vibration damping apparatus as a result 
of appropriate selection of the transmission ratio. 
For example, a presently known torsional vibration damping apparatus which 
is to be effective between two masses or flywheels adapted to rotate about 
a common axis with as well as relative to each other is designed to 
enhance the comfort of the occupant(s) of a motor vehicle in that its 
energy storing means (e.g., a coil spring or a set of coil springs) is 
designed in such a way that its spring rate or stiffness is reduced at 
least within the first stage or portion of its characteristic curve. This 
can be readily achieved if the energy storing means employs a series of 
coil springs. Furthermore, such energy storing means can be utilized in 
conjunction with two masses which are rotatable relative to each other and 
which can effect a change of the moment of inertia as a function of 
movement; this can result in a reduction (or even elimination) of peaks 
(if any) of transmitted torque. Thus, it is possible to equip the power 
train of a motor vehicle with a composite flywheel which is specifically 
designed and particularly well suited for use in a specific make of a 
motor vehicle. 
The kinematics of a planetary which operates between the primary and 
secondary masses of a composite flywheel can be selected to exert a 
beneficial influence upon the composite flywheel as well as upon the 
entire power train within a wide range of the magnitudes of transmitted 
torque. For example, if the planetary is designed in such a way that its 
input side is being acted upon by mutually opposing damping forces in the 
free mass, it is possible to reduce the peaks of torque acting upon the 
output element (such as a camshaft or a crankshaft) of an engine. 
Furthermore, the planetary can reduce undesirable accelerations of RPM at 
the output side, i.e., at the side which is remote from the prime mover 
and serves to transmit torque to a transmission, e.g., by way of a 
friction clutch or any other suitable clutch. This, in turn, prolongs the 
useful life of various auxiliary aggregates (such as the aforementioned 
light generator (dynamo), the air conditioning system, the pump of the 
power steering mechanism and others) which receive motion from the output 
element of the engine downstream of the flywheel. 
To summarize, available torsional vibration damping apparatus of the above 
outlined character can take advantage of three important expedients or 
principles, namely friction, velocity-related damping, and acceleration 
related damping. 
In certain presently known torsional vibration damping apparatus, the 
primary mass is rotatable relative to at least one carrier forming part of 
a planetary and mounting at least one planet pinion which meshes with a 
sun gear or sun wheel and an internal gear or wheel. One of the primary 
and secondary masses of such apparatus is provided with an abutment which 
acts upon the energy storing means of the apparatus between the primary 
and secondary masses whereby the energy storing means bears upon an 
intermediate mass (e.g., a mass including the sun gear, the planet 
carrier(s) and the internal gear). The parameters of movement of the 
intermediate mass vary as a function of variations of the extent and 
direction of angular displacements of the primary and secondary masses 
relative to each other. 
FIGS. 3 and 4 of German patent No. 31 39 658 C2 illustrate a torsional 
vibration damping apparatus wherein the primary mass is provided with a 
friction lining and is fixedly secured to a sun gear on a hub of a 
secondary mass. The planetary which includes the sun gear further 
comprises a planet carrier which is secured to the hub and has limited 
freedom of movement relative to the friction lining. The planet pinions 
which are mounted on the carrier mesh with the sun gear as well as with an 
internal gear on one or more covering panels for the hub. The internal 
gear can turn relative to the hub. The panels have windows for discrete 
springs of the energy storing means. 
In the just described conventional torsional vibration damping apparatus, 
torque which is being transmitted to the primary mass is transmitted to 
the sun gear by way of the friction lining. In the event of fluctuations 
of transmitted torque, the planet pinions rotate relative to the sun gear 
and relative to the internal gear to thus effect a change in the angular 
position of the aforementined panels relative to the hub. This entails a 
stressing of the springs, i.e., the energy storing means is caused to 
store energy. 
By properly selecting the ratio of the planetary, the extent of deformation 
of the springs in the windows of the panels can be selected in such a way 
that it is more satisfactory than in a torsional vibration damping 
apparatus which does not employ a planetary, i.e., wherein the springs of 
the energy storing means are stressed to an extent which is directly 
proportional to the extent of angular movement of the primary and 
secondary masses relative to each other. It has been found that the 
stressing of springs, which form part of the energy storing means, by way 
of a planetary is much more effective to reduce or to eliminate the 
influence of undesirable fluctuations of transmitted torque. However, the 
just described torsional vibration damping apparatus also exhibit a 
serious drawback, namely the mass moment of inertia at the output side is 
small which affects the ability of the patented apparatus to counteract or 
absorb pronounced fluctuations of transmitted torque. 
A torsional vibration damping apparatus which can counteract more 
pronounced fluctuations of torque and is installed between the primary and 
secondary masses of such apparatus (e.g., a twin-mass flywheel) is 
disclosed, for example, in German patent No. 36 30 398 C2. This rather 
rudimentary apparatus merely employs a set of springs which are stressed 
to a greater or lesser extent, depending upon the magnitude of the angle 
of rotation of the primary and secondary masses relative to each other. A 
drawback of such apparatus is that their ability to absorb or counteract 
fluctuations of torque is rather limited though they are capable of 
absorbing some of the fluctuations regardless of their magnitude. 
A comparison of torsional vibration damping apparatus which merely employ a 
set of springs with those which employ energy storing means in conjunction 
with planetaries indicates that those using planetaries exhibit at least 
some important advantages including the following: 
If the primary mass receives torque so that it begins to rotate relative to 
the secondary mass (or vice versa), the primary mass transmits a first 
portion of the torque to the secondary mass whereas the remaining second 
portion of such torque is transmitted to the aforementioned intermediate 
mass (which can include the sun gear, the planet carrier and the internal 
gear of the planetary). The ratio of the first and second portions of the 
torque being transmitted by the primary mass (as concerns the magnitudes 
and the directions of action of the first and second portions of the 
torque) is dependent upon the construction of the planetary and the manner 
in which the planetary is operatively connected with the primary and/or 
with the secondary mass. It is possible to design and install the 
planetary in such a way that the magnitude of the first and/or the second 
portion of the engine torque being transmitted by an apparatus employing a 
planetary exceeds the torque being transmitted to the primary mass. 
However, by mounting the springs of the energy storing means in two sets 
one of which damps the fluctuations (if any) of the first portion of 
transmitted torque and the other of which damps the fluctuations of the 
second portion of transmitted torque, it is possible to ensure that the 
torque being transmitted by the secondary mass a least approximates the 
torque being transmitted to the primary mass. The two sets of springs of 
the energy storing means do not undergo any pronounced deformation but can 
effect a desirable "smoothing" of the respective portions of the torque 
being transmitted by the primary mass, i.e., the fluctuations of the 
torque being transmitted by the secondary mass are or can be much less 
pronounced than those of the torque being transmitted to and by the 
primary mass. Moreover, the inertia of the secondary and intermediate 
masses does not greatly affect the quality of the damping action provided 
that the magnitudes of the first and second portions of the torque being 
transmitted by the primary mass are substantial. On the other hand, if the 
magnitudes of the two portions of the torque being transmitted from the 
primary mass (a) directly to the secondary mass and (b) to the 
intermediate mass are relatively small, the difference between the RPM of 
the secondary mass and the RPM of the intermediate mass is very pronounced 
with the result that the springs undergo a substantial deformation and the 
inertia of the secondary and intermediate masses appears to be much 
greater. 
The above enumerated experiences with conventional torsional vibration 
damping apparatus employing a planetary would indicate that the planetary 
and its connection with at least one of the primary and secondary masses 
should be selected with a view to ensure a pronounced damping of the 
fluctuations of transmitted torque prior to the transmission of the thus 
influenced torque to the part or parts being driven by the secondary mass. 
This holds true irrespective of which of the masses (other than the 
intermediate mass) acts as a primary mass or a secondary mass. It is to be 
borne in mind that the ratio of a planetary changes when a vehicle is 
coasting, i.e., if the normally secondary mass serves to transmit torque 
to the normally primary mass because, in lieu of transmitting motion from 
the sun gear, to the internal gear the planet pinions then transmit motion 
from the internal gear to the sun gear (or the other way around). 
OBJECTS OF THE INVENTION 
An object of the invention is to provide a torsional vibration damping 
apparatus which is simpler, longer-lasting and more reliable than 
heretofore known apparatus. 
Another object of the invention is to provide a novel and improved 
combination of a planetary with the primary and secondary masses of a 
composite flywheel. 
A further object of the invention is to provide a novel and improved 
combination of a planetary and energy storing means in a composite 
flywheel. 
An additional object of the invention is to provide a novel and improved 
combination of a planetary, of energy storing means and the primary mass 
of a composite flywheel. 
Still another object of the invention is to provide a novel and improved 
combination of a planetary, energy storing means and the secondary mass of 
a composite flywheel. 
A further object of the invention is to provide a novel and improved 
composite flywheel which is suited for use in the power trains of motor 
vehicles as a superior substitute for conventional composite flywheels 
with or without planetaries. 
Another object of the invention is to provide a torsional vibration damping 
apparatus which can exert a beneficial influence upon the engine of a 
motor vehicle. 
An additional object of the invention is to provide a novel and improved 
power train for use in a motor vehicle between the engine and the wheels. 
Still another object of the invention is to provide a novel and improved 
method of reducing or eliminating undesirable fluctuations of torque which 
is being transmitted to the primary mass of a composite flywheel wherein 
the connection between the primary and secondary masses comprises energy 
storing means and a planetary. 
SUMMARY OF THE INVENTION 
One feature of the invention resides in the provision of a torsional 
vibration damping apparatus which comprises first and second masses 
rotatable with and relative to each other about a common axis, means for 
transmitting torque between the first and second masses including energy 
storing means acting in a circumferential direction of the first and 
second masses and a planetary, and means for limiting the magnitude of the 
torque which is transmittable between the first and second masses. The 
apparatus can further comprise means for connecting one of the first and 
second masses to a rotary component of a prime mover (e.g., to the 
crankshaft or camshaft of a combustion engine), and means for connecting 
the other of the first and second masses with a rotary component of a 
driven arrangement, e.g., with a rotary component of a manual, automated 
or automatic change-speed transmission in a motor vehicle. 
Another feature of the invention resides in the provision of a torsional 
vibration damping apparatus which comprises a rotary torque transmitting 
first component, a torque receiving second component which is rotatable 
with and relative to the first component about a common axis, means for 
transmitting torque between the first and second components, and means for 
limiting the magnitude of torque which is transmittable from one of the 
first and second components to the other of the first and second 
components (and more specifically between a (first) mass or flywheel 
forming part of the first component and a (second) mass or flywheel 
forming part of the second component). 
The means for transmitting torque between the first and second components 
comprises (a) energy storing means and (b) a planetary including at least 
one planet carrier which is rotatable about the common axis relative to 
the first component, at least one planet pinion rotatably mounted on the 
at least one carrier, an internal gear which is coaxial with the at least 
one carrier and meshes with the at least one pinion, and a sun gear which 
meshes with the at least one pinion. One of the first and second 
components is provided with means for stressing the energy storing means 
in response to rotation of the components relative to each other. The 
aforementioned first and second masses are rotatable at a plurality of 
speeds and relative to each other in clockwise and counterclockwise 
directions, and the energy storing means is installed in at least one of 
the first and second components to react against at least one of the first 
and second masses and to bear against at least one intermediate mass 
forming part of the planetary and being rotatable about the common axis at 
a velocity which is dependent upon the aforementioned speed and upon the 
direction of rotation of at least one of the first and second masses 
relative to the other of the first and second masses. The intermediate 
mass can include the sun gear, the at least one planet carrier and/or the 
internal gear of the planetary. 
The at least one pinion of the planetary can be installed and utilized in 
such a way that it is operative to establish a connection between one of 
the first and second masses on the one hand and the other two masses on 
the other hand. The energy storing means of such apparatus can be arranged 
to couple one of the first and second masses with the at least one 
intermediate mass. 
Alternatively, the energy storing means can operate between the first and 
second masses and the at least one pinion then couples the at least one 
intermediate mass with at least one of the first and second masses. 
Still further, the at least one pinion can couple one of the first and 
second masses with the at least one intermediate mass and the energy 
storing means then operates between the first and second masses. 
The internal gear can form part of one of the first and second masses, and 
the at least one intermediate mass can include the at least one planet 
carrier. 
Alternatively, one of the first and second masses can include the at least 
one carrier and the at least one intermediate mass then includes the 
internal gear. 
One of the first and second masses can define a recess for a portion at 
least of the planetary. Such portion of the planetary can include the 
internal gear and the at least one planet carrier. The recess can include 
an at least partially closed chamber for a supply of grease, oil or other 
suitable viscous (such as highly viscous) material. Such apparatus can 
further include means for at least partially sealing the chamber against 
the escape of viscous material. The planetary can comprise a plurality of 
pinions which are spaced apart from each other in the circumferential 
direction of the first and second components, and the at least one carrier 
can include portions which are spaced apart from each other in the 
direction of the common axis; the pinions and the internal gear can be 
disposed between the spaced-apart portions of the at least one carrier. 
Such spaced-apart portions of the at least one carrier can form part of 
the aforementioned sealing means for the chamber. The at least one carrier 
can include a first part which is remote from and a second part which is 
nearer to the common axis, the first part can be confined in one of the 
first and second masses, and the aforementioned spaced-apart portions of 
the at least one carrier can be closely adjacent that one of the first and 
second masses which confines the second part of the at least one carrier. 
That one of the first and second masses which defines the recess can 
include a ring which surrounds the chamber, and the sealing means can 
include a substantially plate-like portion of such ring. The sealing means 
can further comprise a substantially plate-like wall which extends from 
the ring substantially radially inwardly toward the common axis between 
the chamber and the other of the first and second masses. 
One of the first and second masses has a side which confronts the other of 
the first and second masses, and the apparatus can further comprise means 
for locating such other mass against axial movement relative to the one 
mass. The locating means can be borne by one of the first and second 
masses and can comprise at least one friction ring located at a 
predetermined radial distance from the common axis. 
The planetary has a first portion which is more distant from and a second 
portion which is nearer to the common axis and is provided with at least 
one projection. Such apparatus can further comprise a friction generating 
device which is provided on one of the first and second masses and has at 
least one socket receiving the at least one projection with a 
predetermined play in a circumferential direction of the first and second 
components. The at least one carrier can form part of the second portion 
of the planetary. 
The apparatus can comprise a friction generating device which is disposed 
between one of the first and second masses and a portion of the planetary, 
as seen in the direction of the common axis. Such friction generating 
device can comprise a diaphragm spring and a friction disc which is 
engaged by the diaphragm spring. The portion of the planetary can include 
the sun gear. 
At least a portion of the energy storing means can be confined in a chamber 
provided in one of the first and second masses, and this one of the first 
and second masses can be provided with at least one abutment for the 
energy storing means. The latter can react against such at least one 
abutment to bear against the at least one carrier of the planetary. The 
aforementioned recess for a portion at least of the planetary is adjacent 
the chamber for the energy storing means, and such recess is also adjacent 
the other of the first and second masses. The chamber can extend in the 
direction of the common axis as well as in a circumferential direction of 
the two components, and the chamber can further receive a portion of the 
planetary; such portion of the planetary can include the internal gear and 
the at least one pinion. One of the first and second masses can be 
provided with a wall which extends substantially radially of the common 
axis and cooperates with a portion of the planetary to at least 
substantially seal the chamber; such portion of the planetary can include 
the at least one pinion. The at least one carrier of the planetary can be 
mounted on that one of the first and second masses which is provided with 
the chamber, and the apparatus can further comprise a bearing for the 
other of the first and second masses; such bearing can be provided on the 
at least one carrier. 
The at least one carrier of the planetary can rotatably mount one of the 
first and second masses. 
It is preferred to install a bearing between at least two of the first, 
second and intermediate masses in order to maintain such two masses in 
predetermined positions relative to each other (as seen radially of the 
common axis). The at least one planet carrier can form part of the 
intermediate mass, and one of the first and second masses can include a 
hub which is coaxial with the other of the first and second masses; the 
bearing can be disposed between the at least one carrier and the hub. The 
arrangement can be such that the bearing is disposed between a hub which 
is carried by the first mass and a support which is provided on the second 
mass. 
The bearing can constitute an antifriction bearing which includes at least 
one annulus of spherical or other suitable rolling elements, a first race 
which surrounds a hub of one of the at least two masses, and a second race 
which is surrounded by the other of the at least two masses. The at least 
two masses can be provided with means for holding the bearing against 
movement in the direction of the common axis relative to the hub and 
relative to the other of the at least two masses. A thermal insulator can 
be installed between one of the first and second races of the bearing and 
the respective one of the at least two masses. Such insulator can have a 
substantially L-shaped cross-sectional outline. 
Alternatively, the bearing can constitute a friction bearing. Such friction 
bearing can be provided between a hub of the first mass and a support 
forming part of or provided on the second mass and extending substantially 
radially of the common axis. 
Regardless of whether the bearing is a friction bearing or an antifriction 
bearing, it can be provided between a hub of the first mass and a radially 
inner portion of the second mass. The hub can include a larger-diameter 
portion more distant from the radially inner portion of the second mass 
and a smaller-diameter portion which is surrounded by the bearing and by 
the radially inner portion of the second mass. Such bearing is or can be 
narrow as seen radially of the common axis, i.e., the smaller-diameter 
portion of the hub can be closely adjacent the radially inner portion of 
the second mass (as seen in a direction radially of the common axis). 
The sun gear of the planetary can surround and can be centered by the 
bearing. 
The energy storing means can comprise one or more coil springs, for 
example, one or more arcuate coil springs. If the number of the coil 
springs is small, each such coil spring can have a length which is a 
multiple (e.g., a large multiple) of the diameters of its convolutions. If 
the energy storing means comprises a relatively large number of coil 
springs, the diameter of a convolution of each such relatively short coil 
spring can be a substantial fraction (e.g., one half or even more) of the 
axial length of the spring. For example, the energy storing means can 
comprise a plurality of coil springs which are disposed end-to-end, which 
operate in series, and which extend in the circumferential direction of 
the first and second components. 
The planetary can be disposed at a first radial distance from the common 
axis, and the energy storing means can be disposed at a greater second 
radial distance from such axis. 
The energy storing means tends to move radially of and away from the common 
axis under the action of centrifugal force in response to rotation of the 
first and second components, and the apparatus can further comprise at 
least one wear-resistant member (e.g., an arcuate trough or shroud) which 
is provided in at least one of the components in the path of radially 
outward movement of the energy storing means. 
The planetary can be designed in such a way that it comprises a plurality 
of stages or ratios. For example, the at least one pinion can include a 
first portion which meshes with the internal gear, and a different second 
portion which is coaxial with the first portion and meshes with the sun 
gear. 
If the first component is arranged to receive torque from a prime mover 
which is designed to transmit a predetermined maximum torque, the torque 
limiting means of the improved apparatus can be operative to permit the 
transmission of a torque which at least matches the predetermined maximum 
torque. 
The at least one carrier of the planetary can form part of the torque 
limiting means. Furthermore, the at least one carrier of the planetary can 
be connected with the torque limiting means. The latter can be arranged to 
rotate with the at least one carrier. 
The torque limiting means can be installed to frictionally engage one of 
the first and second masses, particularly the first mass. 
If one of the first and second masses has a chamber for a portion of or for 
the entire energy storing means, and if one of the first and second masses 
carries or includes a wall which bounds a portion of such chamber, the 
torque limiting means can be constructed, assembled and installed to 
cooperate with such wall. For example, the wall can be of one piece with 
the respective mass, and such mass could be constituted by the first mass. 
The torque limiting means can comprise at least one friction lining and/or 
at least one resilient element which is stressed in the direction of the 
common axis. Such resilient element can comprise or constitute a diaphragm 
spring. The resilient element of the torque limiting means can bear upon a 
wall bounding a portion of the aforementioned chamber which contains a 
supply of viscous material. 
The apparatus can comprise a first friction generating device which forms 
part of or constitutes the torque limiting means, and at least one 
additional friction generating device which operates between two of the 
first, second and intermediate masses. The torque limiting means can be 
disposed at a greater first and the at least one additional friction 
generating device can be disposed at a lesser second radial distance from 
the common axis. 
For example, the improved apparatus can comprise a friction generating 
device which operates between the first and second components to oppose 
rotation of such components relative to each other, at least after the two 
components complete a predetermined angular movement relative to each 
other. A form-locking connection can be provided between such friction 
generating device and one of the first and second masses, particularly 
between the friction generating device and the second mass. Such 
form-locking connection can be designed to establish a predetermined 
extent of movability between the friction generating device and one of the 
first and second masses. 
The improved apparatus can also comprise means for shielding the planetary 
against overstressing. Such shielding means can comprise at least one stop 
which operates in parallel with the planetary. The shielding means can 
consist of or contain a resilient material, e.g., an elastomeric material. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved torsional 
vibration damping apparatus itself, however, both as to its construction, 
its mode of operation and the mode of assembling and installing the same, 
together with numerous additional important features and advantages 
thereof, will be best understood upon perusal of the following detailed 
description of certain presently preferred specific embodiments with 
reference to the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIGS. 1 and 2 illustrate a torsional vibration damping apparatus which 
constitutes a composite flywheel having a rotary torque transmitting first 
component 3 and a rotary torque receiving second component 46 which is 
rotatable with as well as relative to the component 3 about a common axis 
54. The component 3 includes a first flywheel or mass 1 (hereinafter 
called mass, first mass or primary mass), and the component 46 includes a 
second flywheel or mass 45 (hereinafter called mass, second mass or 
secondary mass). The mass 1 carries or is of one piece with a starter gear 
2 which meshes with a starter pinion (not shown in FIGS. 1 and 2). 
The radially inner portion of the primary mass 1 is affixed to a hub 4 by a 
set of threaded fasteners 5. These fasteners further serve to secure the 
hub 4 to the rotary output element (such as a camshaft or a crankshaft) of 
a combustion engine in a passenger car, a truck or another motor vehicle, 
as well as to connect the hub with a sun gear or sun wheel 7 of a 
planetary and also with a flange 8. The planetary further comprises a 
two-piece planet carrier 9 the disc-shaped parts or portions of which are 
disposed at the opposite sides of the sun gear 7 (as seen in the direction 
of the axis 54); this carrier 9 constitutes an intermediate mass 50 which 
is flanked by the masses 1 and 45 (again as seen in the direction of the 
axis 54). FIG. 2 shows that the right-hand portion of the planet carrier 9 
(i.e., of the intermediate mass 50) extends radially inwardly all the way 
to the smaller-diameter portion of the external surface of the flange 8. 
The left-hand portion of the carrier 9 (as viewed in FIG. 2) has a 
radially inner or innermost part which carries a set of projections 10 
extending with play (as seen in the circumferential direction of the 
components 3 and 46) into the recesses 12 of a friction generating device 
13. The device 13 is located between the primary mass 1 and the sun gear 
7, as seen in the direction of the axis 54, and comprises at least one 
diaphragm spring 15, an intermediate ring 16 and a friction disc 17. The 
diaphragm spring 15 is stressed in the direction of the axis 54; it reacts 
against the planetary and bears upon the ring 16 so that the latter urges 
the friction disc 17 against that side of the primary mass 1 which faces 
away from the engine of the motor vehicle. 
The means for connecting the two portions of the planet carrier 9 to each 
other comprises a set of hollow sleeve-like shafts 18 which are disposed 
at the same radial distance from the axis 54 and each of which mounts a 
discrete pinion 20 of the planetary. The axes of the shafts 18 are 
parallel to the axis 54 and each such shaft has a radially outwardly 
extending collar 21 engaging the outer side of the left-hand portion of 
the carrier 9 (as viewed in FIG. 2). The shafts 18 are tapped and their 
internal threads mate with the external threads of fasteners 22 having 
heads which abut the exposed side of the right-hand portion of the carrier 
9 (as viewed in FIG. 2). This ensures that the two portions of the carrier 
9 are maintained at a desired axial distance from each other and the 
shafts 18 can rotatably support the respective pinions 20. Each such 
pinion meshes with the sun gear 7 and with an internal gear 24 of the 
planetary. The latter is mounted in the radially outer section of the 
carrier 9 and is affixed to a ring 26 by threaded fasteners 25. The ring 
26 surrounds the internal gear 24 as well as the radially outermost parts 
of the two portions of the planet carrier 9. 
The internal gear 24 is provided with several (for example, three) 
equidistant cutouts or windows 27 which are disposed radially outwardly of 
the pinions 20 and extend in the circumferential direction of the 
components 3 and 46. These windows receive three sets 28 of arcuate coil 
springs 30 which constitute an energy storing means cooperating with the 
planetary to form therewith a system or means for the transmission of 
torque between the masses 1 and 45. 
Each of the illustrated sets 28 comprises at least three coil springs 30 
and each such set is confined between a pair of mobile abutments 31 
normally bearing against the adjacent shoulders 32 in the respective 
window 27. In other words, the abutments 31 can stress the springs 30 of 
the respective sets 28 when they are caused to move away from the 
respective shoulders 32. The springs 30 of each set 28 are separated from 
each other by shoes 33 which are slidable along the internal surface of 
the ring 26. 
It is within the purview of the invention to replace each set 28 of several 
discrete relatively short coil springs 30 with a single elongated arcuate 
coil spring which has end convolutions normally abutting the two shoulders 
32 in the respective window 27 of the internal gear 24. The axial length 
of each such relatively long coil spring can be a multiple (even a very 
large multiple) of the diameter of any of its convolutions. On the other 
hand, the diameter of a convolution of each of the illustrated relatively 
short coil springs 30 can be a rather substantial fraction (e.g., 25% or 
50%) of its axial length. If each window 27 receives a single relatively 
long arcuate coil spring, such spring tends to move radially outwardly 
under the action of centrifugal force when the components 3 and 46 are 
caused to rotate, whereby the radially outer portions of at least some 
(median) convolutions of such elongated coil spring tend to bear against 
the internal surface of the radially outwardly adjacent part (such as the 
ring 26). This ring can constitute an equivalent of the wear-resistant 
linings disclosed in commonly owned U.S. Pat. No. 4,946,420 granted Aug. 
7, 1990 to Johann Jackel for "Apparatus for damping torsional vibrations". 
This patent (the disclosure of which is incorporated herein by reference) 
further discloses the advantages of employing elongated coil springs which 
are properly curved or bent or arched prior to insertion into a composite 
flywheel so that their curvature (prior to insertion) matches or at least 
approximates the required curvature subsequent to completion of the 
inserting operation. The patent to Jackel further describes and shows the 
manner of affixing one mass of a composite flywheel to the rotary output 
element of a prime mover (such as a combustion engine), as well as the 
manner of securing the other mass of the composite flywheel to a rotary 
input element of a change-speed transmission, e.g., by way of a friction 
clutch. 
The illustrated coil springs 30 are held against direct contact with the 
internal surface of the ring 26 by the shoes 33 each of which includes a 
radially inner portion extending between a pair of neighboring springs 30 
and a radially outer portion abutting the internal surface or being close 
to such internal surface. The abutments 31 can also have radially outer 
portions which actually contact or are adjacent the internal surface of 
the ring 26. 
Regardless of whether the ring 26 is engaged by the convolutions of coil 
springs or by shoes, there develops a frictional hysteresis which is a 
function of the centrifugal force and is effective in parallel with the 
springs 30 or with the aforementioned longer arcuate coil springs. 
Regardless of whether the energy storing means comprises the illustrated 
sets 28 of several springs 30 each or longer arcuate coil springs, the 
springs can be dimensioned in such a way that they are installed in 
unstressed or practically unstressed condition. Such mounting in 
unstressed or practically unstressed condition is facilitated if the 
energy storing means comprises relatively long curved springs which are 
adequately arched prior to installation in the windows 27. 
It is also possible to provide the springs 30 with flats of the type 
disclosed in published German patent application No. 44 06 826 and in the 
corresponding United States Letters Patent the disclosure of which is 
incorporated herein by reference. 
The springs 30 of the three sets 28 further extend into recesses or windows 
35 provided in each of the two portions of the two-piece carrier 9 at 
opposite sides of the windows 27 in the gear 24. The abutments 31 at the 
longitudinal ends of the sets 28 of coil springs 30 can engage the 
shoulders 36 at the longitudinal ends of the windows 35 in the two 
portions of the carrier 9 so that the springs 30 are compelled to store 
energy (or additional energy) when the internal gear 24 and the carrier 9 
are caused to turn relative to each other in either direction. The 
reference characters 38 denote in FIGS. 1 and 2 composite windows or 
channels each of which includes a centrally located window 27 of the 
internal gear 24 and two windows 35 provided in the two portions of the 
carrier 9 at opposite sides of the respective window 27. Each such 
composite window or channel 38 receives a set 28 of end-to-end arranged 
coil springs 30. 
The means for sealing the channels or chambers or compartments 38; for the 
sets 28 comprises a first plate-like sealing element 40 which (in the 
embodiment of FIGS. 1 and 2) is of one piece with the ring 26 and extends 
radially inwardly toward the axis 54. The radially inner portion of the 
sealing element 40 is located at the friction generating device 13. The 
other sides of the channels or chambers or compartments 38 are sealed by 
another plate-like sealing element 42 which is secured to the ring 26 and 
extends between the inner side of the secondary mass 45 and the adjacent 
portion of the planet carrier 9 all the way to the flange 8. The ring 26 
and the two plate-like sealing elements 40, 42 together constitute a 
sealing device or sealing means 43 which defines a chamber or compartment 
44, and such chamber or compartment is at least partially filled with a 
viscous material, such as a highly viscous oil or grease. 
The chamber or compartment 44 is provided in the secondary mass 45 which 
latter thus confines or at least partially receives the two-piece planet 
carrier 9, the planet pinions 20, the sun gear 7 and the internal gear 24 
of the planetary as well as the springs 30 of the three sets 28 together 
constituting the energy storing means of the improved torsional vibration 
damping apparatus. This secondary mass 45 is fixedly secured to the ring 
26, and these two parts 26, 45 together constitute the second component 46 
of the composite flywheel. This component 46 can constitute the flywheel 
(counterpressure plate) of a friction clutch which serves to transmit 
torque to the input element of a variable-speed transmission or another 
driven arrangement in a motor vehicle. Reference may be had again to the 
aforementioned U.S. Pat. No. 4,946,420 which illustrates a suitable 
friction clutch 7 having a counterpressure plate 4 (corresponding to the 
component 46 in FIGS. 1 and 2 of the present case) which is provided with 
a friction surface 4a engageable by the adjacent friction linings of a 
clutch disc 9. Such friction surface can be provided on the right-hand 
side of the mass 45 (as viewed in FIG. 2). 
The constituents 7, 9, 20 and 24 of the planetary in the torsional 
vibration damping apparatus of FIGS. 1 and 2 are held in proper positions 
by the ring 26 and the plate-like sealing elements 40, 42. Another 
friction generating device 47 is provided to hold the ring 26 against 
undesirable axial movements, and such friction generating device comprises 
a friction ring 48 which is stressed in the direction of the axis 54 to 
operate between the mass 1 and the sealing element 40. The friction 
generating device 47 including the friction ring 48 can be said to 
constitute a means for locating the ring 26 in an optimum axial position 
between the masses 1 and 45; such friction generating device ensures the 
development of a basic friction as soon as the intermediate mass 50 tends 
to turn relative to the primary mass 1 and/or vice versa. The magnitude or 
intensity of friction which is being generated by the device 47 depends on 
the distance of the friction ring 48 from the common axis 54 of the masses 
1 and 45, i.e., upon the effective "friction radius" of the device 47. 
The operation of the torsional vibration damping apparatus of FIGS. 1 and 2 
is as follows: 
If the primary mass 1 receives torque from the output element of a prime 
mover which drives the hub 4, the latter rotates the sun gear 7 which 
causes the planet pinions 20 to rotate about the axes of the respective 
shafts 18 because, at such time, the internal gear 24 is still held 
against rotation about the axis 54. Therefore, the rotating planet pinions 
20 cause their carrier 9 to turn about the axis 54. This entails a 
division or breaking up of the torque which is being transmitted by the 
primary mass 1 into a first portion (first partial torque) which is being 
transmitted to the pinions 20 and thence to the carrier 9 (intermediate 
mass 50), and a second portion (second partial torque) which is being 
transmitted to the internal gear 24. For example, if the torque which is 
being transmitted by the primary mass 1 causes the sun gear 7 to rotate in 
a clockwise direction (as viewed in FIG. 1), the aforementioned first 
partial torque is effective to initiate a rotation of the planet pinions 
20 in a counterclockwise direction and the pinions 20 cause the carrier 9 
to turn in a clockwise direction. 
The two portions of the torque being transmitted by the primary mass 1 
oppose each other and each of these portions can be greater than the 
torque which is being applied to the mass 1. However, such portions of the 
torque are superimposed upon each other when they are transmitted to the 
secondary mass 45 so that the torque being transmitted by the mass 45 to a 
clutch disc or another rotary element (plus the losses due, for example, 
to friction developing in the improved apparatus) matches or closely 
approximates the torque being transmitted to the primary mass 1. However, 
the torque which is being transmitted by the secondary mass 45 is at least 
substantially free of undesirable fluctuations or variations because such 
irregularities are absorbed by the springs 30 of the three sets 28 
constituting the energy storing means acting between the planet carrier 9 
(intermediate mass 50) and the internal gear 24 of the planetary. The 
energy storing means including the sets 28 of coil springs 30 permits an 
angular displacement of the internal gear 24 and the carrier 9 relative to 
each other to an extent which depends upon the extent of deformation 
(stressing) of the coil springs 30. 
The function of the energy storing means including the three sets 28 of the 
coil springs 30 in the torsional vibration damping apparatus of FIGS. 1 
and 2 is as follows: When the carrier 9 is caused (by the planet pinions 
20) to turn relative to the internal gear 24 as a result of the 
transmission of torque from the primary mass 1 to the sun gear 7, the 
shoulders 36 of the carrier 9 cause the abutments 31 at the trailing ends 
of the sets 28 to move away from the respective shoulders 32 of the 
internal gear 24 so that the springs 30 are compelled to store energy and 
the shoes 33 slide along the internal surface of the ring 26. The extent 
of deformation of the coil springs 30 is determined by the selected ratio 
of the planetary, i.e., by the ratio of teeth on the sun gear 7 to the 
teeth in the gear 24. 
The chamber 44 in the secondary mass 45 is at least partially filled with a 
preferably highly viscous material, and such viscous material is displaced 
in the chamber 44 not only because the planet pinions 20 rotate about the 
axes of the respective hollow shafts 18 relative to the sun gear 7 as well 
as relative to the internal gear 24 but also as a result of the 
deformation (stressing) of the coil springs 30. As the teeth of the 
rotating pinions 20 penetrate into the tooth spaces between the external 
teeth of the sun gear 7 and between the internal teeth of the gear 24, 
they displace viscous material in the direction of the axis 54, i.e., 
toward the adjacent sides of the two portions of the carrier 9. Due to 
rotation of the components 3 and 46 about the axis 54, the viscous 
material which has been displaced by the teeth of the pinions 20 tends to 
advance radially outwardly along the inner sides of the two portions of 
the carrier 9. Deformation (stressing) of the springs 30 in the channel 38 
entails a movement of the spring convolutions nearer to each other as well 
as a movement of the shoes 33 in each set 28 toward each other (in the 
circumferential direction of the chamber 38), and this also entails a 
displacement of viscous material in the direction of the axis 54, i.e., 
toward the adjacent inner sides of the sealing elements 40 and 42. The 
rate at which the viscous material is being displaced by the teeth of the 
pinions 20 and by the coil springs 30 increases in response to increasing 
rotational speed of the pinions, and this results in an increasing 
resistance of viscous material to such displacement. In other words, the 
damping action of the viscous material increases proportionally with the 
rotational speed of the pinions 20 about their respective axes relative to 
the internal gear 24. 
If the means for transmitting torque between the primary and secondary 
masses 1 and 45 includes the transmission including the parts 7, 9, 20 and 
24, this leads to the generation of pronounced partial torques (first and 
second portions of torque being transmitted by the mass 1). The phase or 
stage during which the internal gear 24 does not rotate in response to 
rotation of the pinions 20 by the sun gear 7 is very short, i.e., the 
interval during which the primary mass 1 rotates relative to the secondary 
mass 45 and the carrier 9 is short or very short. This, in turn, entails 
that the damping action of viscous material in the chambers 38 and 44 is 
of short duration, i.e., the percentage of damping action furnished by the 
viscous medium in comparison to the damping action of the coil springs 30 
is rather small. Therefore, the quality or intensity of the damping action 
of the apparatus which is shown in FIGS. 1 and 2 is not overly affected if 
the internal gear 24 and/or the planet pinions 20 are installed externally 
of the chamber 44, such as in a recess 51 which is provided in one of the 
masses 1 and 45. 
When the pinions 20 complete that angular movement about the axes of the 
respective hollow shafts 18, i.e., relative to the internal gear 24, which 
is necessary to move (against the opposition of the springs 30) the 
projections 10 on the left-hand portion (as viewed in FIG. 2) of the 
carrier 9 the full length of the sockets 12 of the friction generating 
device 13, any further angular displacement of the carrier 9 under the 
action of the pinions 20 causes the friction ring 17 to slide relative to 
the mass 1 or the intermediate ring 16 to slide relative to the friction 
ring 17 and the mass 1. In either event, the friction ring 17 opposes 
rotation of the carrier 9 relative to the mass 1 and can cause a 
deceleration of the carrier or prevents any further rotation of the 
carrier. The percentage of the thus established hysteresis upon the 
torsional vibration damping action is dependent upon the design and 
dimensioning of the planetary. Thus, if the ratio of the planetary is such 
that the carrier 9 tends to carry out large angular movements relative to 
the primary mass 1, this results in a longer-lasting frictional damping 
action of the friction generating device 13. On the other hand, if the 
ratio of the planetary is such that the planetary causes the establishment 
of large partial torques, and if the friction generating device 13 employs 
a rather strong diaphragm spring 15 (i.e., a diaphragm spring which is 
installed in a highly compressed or stressed condition, as seen in the 
direction of the axis 54), it is possible to regulate the torsional 
vibration damping operation with a higher degree of accuracy and 
reliability. 
In the apparatus of FIGS. 1 and 2, the friction ring 48 of the locating 
means 47 on the primary mass 1 is in uninterrupted frictional engagement 
with the adjacent sealing element 40, i.e., with the ring 26. This means 
that the locating means 47 opposes each and every angular displacement of 
the masses 1 and 45 relative to each other. 
If the functions of the components 3 and 46 are reversed, i.e., if the 
vehicle whose engine normally drives the primary mass 1 is coasting, the 
wheels drive the secondary mass 45 which causes the ring 26 to rotate the 
internal gear 24 which rotates the planet pinions 20 about the axes of 
their respective shafts 18 so that the pinions roll along the external 
teeth of the sun gear 7. Rotation of the sun gear 7 is shared by the mass 
1 which transmits torque to the output element of the engine. It will be 
appreciated that the ratio of the planetary is different when the vehicle 
is coasting because the internal gear 24 then causes the pinions 20 to 
rotate the sun gear 7 whereas, when the sun gear 7 is driven by the 
primary mass 1 (i.e., by the engine), the pinions 20 are caused to rotate 
the internal gear 24. The reason is that the number of internal teeth of 
the gear 24 is different from the number of external teeth of the gear 7. 
When the relative speeds are rather high, it is advisable to install the 
parts of the planetary in the chamber 44, i.e., in the component 46. An 
advantage of such mounting is that the magnitude of the speed at which one 
of the masses 1, 45 turns relative to the other of these masses cannot 
influence the sealing action for the supply of viscous medium within the 
sealing means 43 because all parts (40, 42, 26) of such sealing means 
rotate with the mass 45. 
The ring 26 constitutes a means for fixedly securing the internal gear 24 
to the secondary mass 45 (by way of the fasteners 25 and additional 
fastener means (see FIG. 2) securing the ring 26 to the mass 45). 
The provision of the planetary renders it possible to establish a number of 
locations for the mounting of friction generating means because there are 
numerous pairs of parts which are adjacent and can turn relative to each 
other. 
If the ratio of the planetary is such that it causes the generation of 
large partial torques, the friction generating device 13 can employ a 
strong diaphragm spring 15 the bias of which can be selected with a high 
degree of accuracy. If the partial torques are small or relatively small 
but the angular speeds are high, it is presently preferred to employ a 
weaker diaphragm spring 15 (the bias of which cannot or need not be 
regulated with a high degee of accuracy) and to rely on longer distances 
of operation or effectiveness of the friction generating device 13. 
Depending upon the exact design of the improved torsional vibration damping 
apparatus, the energy storing means (such as the springs 30 or their 
equivalents) can be installed to operate between the masses 1 and 45 or 1 
and 50 or 45 and 50 or between the parts of the planetary or between one 
or more selected parts of the planetary and the mass 1 and/or 45. 
Referring to FIG. 3, there is shown a portion of a torsional vibration 
damping apparatus which constitutes a first modification of the 
aforedescribed apparatus of FIGS. 1 and 2. A difference between the two 
apparatus is that the energy storing means including the springs 30 shown 
in FIG. 3 operates between the primary mass 1 and the planet carrier 9 
which is centered on the hub 4 by a suitable bearing 60 (e.g., an 
antifriction bearing with one or more annuli of balls or other sitable 
rolling elements between an inner race surrounding the hub and an outer 
race surrounded by the radially inner portion of the carrier 9). 
Connectors 61 in the form of pins, rivets or the like are provided to 
secure the carrier 9 to the secondary mass 45. The median portions of the 
connectors 61 (of which only one can be seen in FIG. 3) are surrounded by 
the sleeve-like shafts 18 for the planet pinions 20. The connectors 61 
have first end portions welded to the carrier 9 and second end portions 
anchored in the mass 45. Intermediate portions of the connectors 61 have 
shoulders which maintain the collars 21 of the shafts 18 in abutment with 
the adjacent sides of the respective planet pinions 20. The shafts 18 need 
not be provided with internal threads. The flywheel 1 has a radially 
inwardly extending portion or wall 62 which is adjacent the right hand 
sides of the pinions 21 to hold the pinions in abutment with the collars 
21 of the respective shafts 18. 
The pinions 20 mesh with the sun gear 7 which is affixed to the hub 4 
(i.e., to the primary mass 1), and these pinions further mesh with the 
internal gear 24 which is adjacent the radially outermost portion of the 
wall 62 and is located within the confines of the mass 1. 
The apparatus of FIG. 3 further comprises a friction generating device 13 
which operates between the mass 1 and the planet carrier 9. One or more 
additional friction generating devices (not shown) can be provided between 
pairs of neighboring parts which can turn relative to each other, e.g., 
between the wall 62 and the secondary mass 45. 
The chamber 44 in the apparatus of FIG. 3 is defined by the primary mass 1 
(i.e., the component 3) and its radially extending wall 62, and such 
chamber is at least partially filled with a supply of viscous material. 
The planet pinions 20 cooperate with the internal gear 24 and with the sun 
gear 7 to reduce the likelihood of undesired escape of viscous material 
from the chamber 44. This chamber further receives the sets 28 of the coil 
springs 30 constituting the energy storing means in the apparatus of FIG. 
3. As already described in connection with FIGS. 1 and 2, the viscous 
material in the chamber 44 can furnish a damping action which is 
proportional with the rotational speed. A major part of the sealing action 
for the confined viscous material is furnished by the component 3, i.e., 
by the primary mass.1 and its radially inwardly extending wall 62. 
When the component 3 is driven by the output element of a prime mover, the 
primary mass 1 initially turns relative to the secondary mass 45 of the 
component 46 about ther common axis 54. A first portion of the torque 
which is transmitted by the primary mass 1 is being applied to the planet 
pinions 20 and thence to the internal gear 24. The second portion of such 
torque is being applied to the carrier 9 via connectors 61. This entails 
the development of an angular movement between the carrier 9 and the 
primary mass 1, i.e., the springs 30 of the sets 28 are caused to store 
energy. 
The internal gear 24 constitutes the intermediate mass 50 of the apparatus 
which is shown in FIG. 3. The two portions of transmitted torque are 
superimposed upon each other to furnish a resultant torque which is 
transmitted to the secondary mass 45 of the component 46 by way of the 
connectors 61. The same as in the apparatus of FIGS. 1 and 2, the 
direction of action of the torque being transmitted to the primary mass 1 
of FIG. 3 is counter to the direction of action of partial torque at the 
pinions 20 and the internal gear 24 but the same as the direction of 
action of partial torque being applied to the carrier 9. 
FIG. 4 illustrates a portion of an apparatus which constitutes a 
modification of the torsional vibration damping apparatus of FIG. 3. An 
important difference between these apparatus is that the capacity of the 
chamber 44 in the component 3 of FIG. 4 is selected with a view to 
accommodate the sets 28 of coil springs 30 but not the internal gear 24 
and the pinions 20 of the planetary. The parts 20 and 24 are received in a 
chamber, recess or compartment 51 at the right-hand side of the planet 
carrier 9 (as viewed in FIG. 4). The compartment 51 is adjacent the 
chamber 44, as seen in the direction of the common axis 54 of the 
components 3 and 46. 
The embodiment of FIG. 4 can be put to use when the ratio of the planetary 
is such that the angular speed of the pinions 20 is low so that the 
damping action of such pinions in combination with the viscous material in 
the chamber 44 is relatively weak or plain negligible. It is to be 
recalled that the damping action of the confined viscous material is 
dependent upon the rotational speed of the planet pinions. 
The reference numerals shown in FIGS. 3 and 4 but not specifically 
mentioned in connection with the descriptions of the apparatus shown in 
FIGS. 3 and 4 denote parts which are identical with or clearly analogous 
to the similarly referenced parts of the apparatus shown in FIGS. 1 and 2. 
This also holds true for the embodiments which will be described with 
reference to FIGS. 5 through 15. 
FIG. 5 shows schematically certain component parts of a further torsional 
vibration damping apparatus wherein the sets 28 of springs (such as the 
coil springs 30 in the apparatus of FIGS. 1 and 2) are installed to 
operate between the primary mass 1 of the component 3 and the carrier 9 
for the planet pinions 20 of the planetary. The pinions 20 mesh with the 
centrally located sun gear 7 and with the internal gear 24 which is 
connected with the secondary mass 45 of the component 46. The carrier 9 
constitutes the intermediate mass 50 and is accelerated by one of the two 
partial torques transmitted by the primary mass 1 when the latter is 
driven by the output element of a prime mover. 
The right-hand portion of FIG. 15 shows a clutch disc 90 which forms part 
of a friction clutch between the apparatus of FIG. 5 and a change-speed 
transmission and which is rotated by the mass 45 when the friction surface 
at the right-hand side of the mass 45 is engaged by a friction lining of 
the clutch disc 90, e.g., under the action of an axially reciprocable 
pressure plate corresponding to the pressure plate 8 in FIG. 1 of U.S. 
Pat. No. 4,946,420 to Jackel. 
FIG. 6 illustrates a portion of a torsional vibration damping apparatus 
wherein, in contrast to the apparatus of FIG. 5, the sets 28 of springs 
constituting the energy storing means operate between the primary flywheel 
1 of the component 3 and the internal gear 24 of the planetary. The 
internal gear 24 is rigid with the secondary mass 45 of the component 46. 
The carrier 9 again constitutes the intermediate mass 50 and supports a 
set of pinions 20 which mesh with the internal gear 24 as well as with a 
sun gear 7 of the planetary. The sun gear 7 is coaxial with and is secured 
to the primary mass 1. The intermediate mass 50 (carrier 9) is borne by 
the pinions 20 and is acceleratable by one of the two portions of torque 
being transmitted by the component 3. 
FIG. 7 illustrates certain details of a further torsional vibration damping 
apparatus which constitutes an additional modification of the previously 
described apparatus. Thus, the sets 28 of springs forming part of the 
energy storing means are installed to operate between the internal gear 24 
and the carrier 9 of the planetary, i.e., between the internal gear 24 and 
the secondary mass 45 which is rigid with the carrier 9. It will be seen 
that, in contrast to the construction and operation of the previously 
described apparatus, the energy storing means including the sets 28 of 
springs shown in FIG. 7 operates at the output side of the apparatus. The 
carrier 9 forms part of the component 46 (i.e., of the mass 45), and the 
internal gear 24 constitutes the intermediate mass 50 which is coupled to 
the primary mass 1 by the energy storing means. The sun gear 7 is affixed 
to and coaxial with the primary mass 1. 
In the apparatus of FIG. 8, the sun gear 7 of the planetary is affixed to 
the primary mass 1 of the component 3, and the carrier 9 of the planetary 
is affixed to or constitutes the secondary mass 45 of the component 46. 
The energy storing means including the sets 28 of coil springs or other 
suitable resilient elements is installed to operate between the primary 
mass 1 and the secondary mass 45, i.e., between the mass 1 and the planet 
carrier 9. Thus, and in contrast to the embodiment of FIG. 7, the energy 
storing means including the sets 28 is installed to operate at the input 
side of the torsional vibration damping apparatus of FIG. 8. 
The improved apparatus can utilize several energy storing means, for 
example, a first energy storing means at the input side (as shown in FIGS. 
1 to 6 and 8) and a second energy storing means at the output side (as 
shown in FIG. 7). The basic mode of operation of all of the aforedescribed 
apparatus is the same. Thus, the torque being transmitted to the primary 
mass 1 is split into two partial torques one of which is branched off to 
the secondary mass 45 and the other of which is branched off to the 
intermediate mass 50. The latter can include or be constituted by the 
internal gear 24 of by the planet carrier 9. The two partial torques are 
merged into an output torque which is transmitted by the secondary mass 
45. Due to the provision of one or more energy storing means, the two 
partial torques effect an angular movement of the primary and secondary 
masses 1, 45 relative to each other and the fluctuations of torque being 
transmitted to the input mass 1 are either reduced or eliminated due to 
the action of the planetary, due to the action of the energy storing means 
as well as due to the action of one or more friction generating devices. 
Referring to FIG. 9, there is shown a portion of a further torsional 
vibration damping apparatus wherein the hub 4 is surrounded by the inner 
race of a schematically illustrated antifriction bearing 60 having an 
outer race which is surrounded by a radially inwardly extending wall or 
support 62 carried by the secondary mass 45. The outer race of the bearing 
60 is directly surrounded by one or more thermal insulators 65 which 
reduce or prevent the transfer of heat from the secondary mass 45 (which 
is assumed to constitute the counterpressure plate of a friction clutch 
and is heated as a result of slippage of friction linings of the clutch 
disc relative to the pressure plate and/or counterpressure plate) to the 
races and to the rolling elements 63 of the bearing 60. The thermal 
insulator 65 can constitute a circumferentially complete part or a 
composite part and can have a substantially L-shaped cross-sectional 
outline. 
The wall or support 62 can form part of or (as actually shown in FIG. 9) 
can be affixed to the secondary mass 45. 
The hub 4 has an external shoulder which cooperates with the radially 
outermost portion of the flange 8 to maintain the inner race of the 
antifriction bearing 60 in the illustrated optimal axial position relative 
to the thermal insulator 65, wall or support 62 and hub 4. The outer race 
of the bearing 60 is held in a desired axial position by a radially 
inwardly extending portion of the wall or support 62 and by one leg of the 
thermal insulator 65 which is recessed into the radially inner portion of 
the part 62. 
An advantage of the bearing 60 is that it ensures an optimal axial 
positioning of the pinions 20, internal gear 24 and sun gear 7 of the 
planetary relative to each other without the development of unbalanced 
masses in spite of the need for some play between the teeth of the pinions 
20 on the one hand and those of gears 7,24 the other hand, 
FIG. 10 illustrates a portion of a torsional vibration damping apparatus 
which differs from the apparatus of FIG. 9 in that the antifriction 
bearing 60 is installed between the hub 4 and the right-hand portion (as 
viewed in FIG. 10) of the two-piece carrier 9 for the pinions 20 of the 
planetary. The right-hand portion of the carrier 9 has a ring-shaped 
radially inner part 70 which surrounds the thermal insulator 65 and 
maintains it in a proper radial and axial position relative to the outer 
race of the bearing 60 including the rolling. elements 63 and further 
having an inner race which is held in a selected axial position by an 
external shoulder of the hub 4 and the flange 8. The just described 
mounting of the bearing 60 again ensures that no unbalanced masses develop 
when the planet pinions 20 mesh with and roll along the internal gear 24 
and the sun gear 7 of the planetary. 
FIG. 11 illustrates a rudimentary (friction) bearing 60 in an apparatus 
which, in other respects, is similar to or practically identical with the 
apparatus of FIG. 9 or 10. The wall or support 62 of the apparatus which 
is shown in FIG. 11 extends radially inwardly, and its radially innermost 
portion constitutes a collar 71 which forms part of the friction bearing 
and slidably engages the adjacent portion 67 of the external surface of 
the hub 4 which is located between the sun gear 7 and the flange 8. The 
bearing 60 of FIG. 11 is designed to establish a metal-to-metal contact 
between the wall or support 62 and the hub 4. However, it is possible (and 
often desirable) to insert a ring (e.g., a plastic ring, not shown) 
between the collar 71 and the surface 67 of the hub 4. 
It will be noted that the friction bearing 60 of FIG. 11 has a minimal 
(negligible) width as measured radially of the common axis of the masses 1 
and 45. Otherwise stated, the wall or support 62 of the secondary mass 45 
is closely (immediately) adjacent the hub 4. 
FIG. 12 shows a portion of an apparatus wherein the hub 4 is relatively 
thin and includes a larger-diameter portion within the primary mass 1 and 
a smaller-diameter portion surrounded by an antifriction bearing 60 which, 
in turn, is surrounded by the radially inwardly extending wall or support 
62 of the secondary mass 45 as well as by the radially inner portion of 
the sun gear 7. The illustrated bearing 60 of FIG. 12 can be replaced by 
an antifriction bearing having a width (as measured radially of the common 
axis of the masses 1 and 45) which is a small fraction of width of the 
illustrated bearing, or by an even thinner friction bearing. All that 
counts is to provide a bearing which can prevent the development of 
unbalanced masses when the planetary using the meshing pinions 20 and 
gears 7, 24 is in use. This is accomplished by ensuring that the relative 
positions of the component parts of the planetary (as seen radially of the 
common axis of the masses 1 and 45) do not change at all or do not change 
beyond a permissible extent. 
Referring to FIG. 13, there is shown an apparatus wherein the carrier 9 of 
the planetary forms part of the primary mass 1 which is rigidly connected 
to or of one piece with the radially inwardly extending wall 62. The 
shafts for the planet pinions 20 are constituted by rivets 22 each having 
one end portion anchored in the mass 1 and another end portion anchored in 
the wall 62. The inner sides of the mass 1 and wall 62 rather closely 
surround the sets 28 of energy storing elements forming part of the energy 
storing means acting between the internal gear 24 and the mass 1. The 
pinions 9 mesh with the internal gear 24 and with the sun gear 7 which, in 
this embodiment of the improved apparatus, is bolted, riveted or otherwise 
non-rotatably affixed to the secondary mass 45. The sets 28 of coil spings 
forming part of the energy storing means are disposed radially outwardly 
of the pinions 20 which, in turn, are installed radially outwardly of the 
friction generating device 13. 
The reference character 72 denotes a wear-resistant liner no shield which 
is installed in the chamber of the primary mass 1 radially outwardly of 
the sets 28 of coil springs forming part of the energy storing means. As 
already pointed ou hereinbefore, the energy storing means tends to move 
radially outwardly under the action of centrifugal force and to rub 
against the radially outwardly adjacent part or parts when the springs of 
such energy storing means are forced to slide relative to the parts which 
cause the springs to store energy in response to angular movements of the 
primary mass 1 and the secondary mass 45 relative to each other. Reference 
may be had to the published German patent application No. 37 45 117 and to 
corresponding United States Letters Patent the disclosure of which is 
incorporated herein by reference. 
In view of its rigid connection with the secondary mass 45, the sun gear 7 
of the planetary shown in FIG. 13 can be considered as a part of the 
component including the mass 45. 
The planetary which is utilized in the apparatus of FIG. 13 has two stages. 
This is due to the fact that each pinion 20 includes a first portion 
meshing with the internal gear 24 and a different second portion meshing 
with the sun gear 7. The number of teeth on the second portion of each 
pinion 20 is greater than the number of teeth on the first portion which 
is coaxial with the second portion. The ratios of the planetary can differ 
to a desired extent depending upon the relationship between the numbers of 
teeth on the first and second portions of the pinions 20. The overall 
ratio of the planetary of FIG. 13 is assumed to have been increased by 
1.3. 
The bearing 60 is installed between the hub of the primary mass 1 and the 
radially inner portion of the secondary mass 45 of the apparatus which is 
shown in FIG. 13. The function and the advantages of such bearing are the 
same as those described in connection with the embodiments shown in FIGS. 
1 to 12. 
The apparatus of FIG. 14 is similar to that of FIG. 13 but it further 
comprises a torque limiting means 73 in the form of a slip clutch 
operating between the primary mass 1 and the carrier 9 for the pinions 20 
of the planetary. Each such pinion is or can be constructed in the same 
way as described in connection with the apparatus of FIG. 13. The carrier 
9 in the apparatus of FIG. 14 is a separately produced part which is 
disposed between the primary mass 1 and the wall 62 of the latter and 
carries rivets 22 serving as shafts for the pinions 20. The torque 
limiting means (slip clutch) 73 includes two friction linings 74, one 
between the mass 1 and the left-hand portion of the carrier 9 and the 
other between the wall 62 and the right-hand portion of the carrier 9. The 
friction linings 74 are optional, i.e., the two halves or portions of the 
composite carrier 9 can bear directly against the inner side of the 
primary mass 1 and against the left-hand side of the wall 62. The torque 
limiting means or slip clutch 73 further comprises a diaphragm spring 75 
which reacts against the wall 62 and bears against the right-hand lining 
74; this causes the shafts 22 (one shown in the form of a rivet) to urge 
the left-hand lining against the mass 1 through the medium of the 
left-hand portion of the carrier 9. The bias of the diaphragm spring 75 in 
the direction of the common axis of the mass 1 and the other masses 
determines the slip torque, i.e., the limit of the magnitude of torque 
being transmittable from the primary mass to the secondary mass of the 
apparatus of FIG. 14. The illustrated diaphragm spring 75 is installed in 
such a way that its radially outer portion reacts against the wall 62 and 
that its radially inner portion bears against the adjacent friction lining 
74, i.e., against the right-hand portion of the carrier 9. 
An important advantage of the slip clutch 73 (an equivalent of such slip 
clutch is preferably installed in each embodiment of the improved 
apparatus) is that it protects the apparatus against excessive stresses 
such as excessive peak loads which could develop, for example, in the 
event of resonance. It is preferred to select the maximum torque which is 
transmissible before the slip clutch 73 becomes active in such a way that 
it at least matches the maximum permissible torque of the engine which 
drives the primary mass 1. 
The chamber 44 which is defined by the mass 1 and its wall 62 is at least 
partially filled with a supply of viscous material. The slip clutch 
(torque limiting means) 73 can serve the additional function of 
constituting a sealing means for the chamber 44 or of contributing to a 
sealing action which prevents uncontrolled escape or expulsion of viscous 
medium from the chamber 44. This renders it possible to eliminate the need 
for a stopper in the opening 76; such opening can serve as a means for 
permitting the introduction of viscous material into the chamber 44. 
However, it is also possible to employ a suitable stopper or other sealing 
means, such as the stopper 76a shown in FIG. 13. It is to be noted that 
the stopper 76a of FIG. 13 can constitute an optional component part of 
the respective apparatus because the consistency of the viscous material 
(e.g., grease) can be readily selected in such a way that it does not 
exhibit any (or any appreciable) tendency to flow radially inwardly toward 
the opening or openings (such as the opening 76 in the apparatus of FIG. 
14). 
The apparatus of FIG. 15 is practically identical with the apparatus of 
FIG. 14 except that it employs a planetary with simpler (single-stage) 
pinions 20. Thus, the ratio of the planetary in the apparatus of FIG. 15 
is determined by the relations between the numbers of teeth on the 
internal gear 24 and the sun gear 7. The apparatus of FIG. 15 also employs 
a torque limiting means in the form of a slip clutch 73 disposed radially 
outwardly of a friction generating device 13. 
FIGS. 14 and 15 show that the carrier 9 of the planetary can cooperate with 
the slip clutch 73; in fact, this carrier can be said to form part of the 
torque limiting means. Such torque limiting means 73 operates between the 
primary mass 1 and the intermediate mass (carrier 9). It is also possible 
to provide torque limiting means which operates between the intermediate 
mass 50 and the secondary mass 45 and/or between the primary and secondary 
masses or between the intermediate mass and the secondary mass, or to 
provide a plurality of torque limiting means (e.g., one between the 
primary and intermediate masses as shown in FIGS. 14 and 15 and another 
between the primary and secondary masses). 
It is normally preferred to employ at least one torque limiting means which 
employs one or more friction linings (such as 74); this renders it 
possible to more accurately select the friction coefficient of a slip 
clutch. 
In each of the illustrated embodiments of the improved torsional vibration 
damping apparatus, the friction clutch 13 and/or an equivalent friction 
clutch can be constructed, assembled and installed in such a way that it 
is effective during each and every stage or only during certain stages of 
angular movement of the primary and secondary masses relative to each 
other. For example, and as actually shown in the drawings, the friction 
clutch 13 can be designed in such a way that it becomes effective upon 
completion of certain initial angular displacement of the primary and 
secondary masses 1 and 45 relative to to each other (depending upon the 
length of the projection 10 and recess 12, as seen in the circumferential 
direction of the components 3 and 46). 
It is often desirable to employ a friction generating device which is 
form-lockingly connected (if necessary with a preselected play) to the 
secondary mass 45. 
Furthermore, it is also often desirable to provide means for shielding the 
planetary against overstressing. Such shielding means can comprise one or 
more stops which are designed to operate in parallel with the planetary. 
The shielding means may (but need not) contain a resilient material (e.g., 
a suitable elastomeric material which is capable of absorbing shocks). 
The improved torsional vibration damping apparatus can be utilized in 
existing models of motor vehicles as a superior substitute for presently 
employed composite flywheels. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of the above outlined 
contribution to the art of torsional vibration damping apparatus and, 
therefore, such adaptations should and are intended to be comprehended 
within the meaning and range of equivalence of the appended claims.