Vibration damping apparatus

Apparatus for damping vibrations between the crankshaft of the engine and the clutch plate of the friction clutch of a motor vehicle has a first flywheel which is driven by the crankshaft, a second flywheel which is rotatable relative to the first flywheel and can rotate the clutch plate, and a torque transmitting unit between the flywheels. The unit employs one or more dampers in an annular chamber of the first flywheel and a slip clutch on the other flywheel. The output element of the damper or dampers is a flange-like device which constitutes a diaphragm spring and transmits torque to an axially stressed resilent disc which forms part of the slip clutch. The disc is riveted to the second flywheel and is adjacent an axially stressed resilient diaphragm seal which engages the first flywheel to seal the chamber from the atmosphere.

BACKGROUND OF THE INVENTION 
The invention relates to improvements in apparatus for damping vibrations 
between the driving and driven (primary and secondary) components of power 
trains. More particularly, the invention relates to improvements in 
apparatus which can be utilized to damp vibrations between the rotary 
output elements of engines and rotary input elements of transmissions in 
motor vehicles. 
Vibration damping apparatus of the above outlined character normally 
comprise a first or primary flywheel which is connectable to the output 
element (e.g., a crankshaft) of an internal combustion engine, a second or 
secondary flywheel which is coaxial with and is rotatable relative to the 
first flywheel and is connectable to the rotary input element of a 
variable speed transmission, and means for transmitting torque between the 
flywheels. Certain presently preferred torque transmitting means include a 
torsionally elastic damper in series with a slip clutch which employs a 
flange-like torque transmitting device. The flange-like device is stressed 
in the axial direction of the flywheels and transmits torque from the 
damper to the slip clutch. 
It is also known to provide one of the flywheels with a chamber which is at 
least partially filled with a viscous fluid and serves to receive a 
portion of the torque transmitting means. The means for stressing the 
flange-like torque transmitting device is carried by the other flywheel, 
and the other flywheel can transmit torque to the input element of the 
transmission by way of an engageable friction clutch. Such design ensures 
that friction heat which is generated during engagement or disengagement 
of the friction clutch is less likely to affect the condition of the 
confined viscous fluid and the operation of those parts of the torque 
transmitting means which are confined in the aforementioned chamber of the 
one flywheel. 
Vibration damping apparatus of the afore-described character are described, 
for example, in German patent application No. 39 09 892 of Johann Jackel 
(published Oct. 12, 1989). Such apparatus exhibit a number of desirable 
advantages. However, the cost of presently known vibration damping 
apparatus is relatively high, primarily (or to a large extent) because the 
assembly of their parts constitutes a complex and time-consuming 
procedure. 
OBJECTS OF THE INVENTION 
An object of the invention is to provide a vibration damping apparatus 
which is simpler and more compact than, but at least as reliable as, 
heretofore known apparatus. 
Another object of the invention is to provide a vibration damping apparatus 
whose useful life is longer than that of conventional apparatus. 
A further object of the invention is to provide a vibration damping 
apparatus which can be utilized with particular advantage in the power 
trains of motor vehicles and can be assembled in a simple and time-saving 
manner. 
An additional object of the invention is to provide a novel and improved 
method of assembling certain constituents of the above outlined vibration 
damping apparatus. 
Still another object of the invention is to provide the vibration damping 
apparatus with novel and improved torque transmitting means between its 
primary and secondary components, particularly between a first flywheel 
which receives torque from an engine and a second flywheel which can 
transmit torque to a transmission, preferably by way of a friction clutch 
or the like. 
A further object of the invention is to provide the vibration damping 
apparatus with novel and improved means for reliably sealing the chamber 
for the supply of viscous fluid. 
Another object of the invention is to provide the vibration damping 
apparatus with novel and improved means for properly stressing and 
mounting the device which transmits torque between the damper or dampers 
and the slip clutch(es) of the means for transmitting torque between the 
primary and secondary components of the apparatus. 
An additional object of the invention is to provide a novel and improved 
connection between the slip clutch(es) and the secondary component of the 
above outlined vibration damping apparatus. 
A further object of the invention is to provide a power train which 
embodies the above outlined vibration damping apparatus. 
Still another object of the invention is to provide a vehicle which 
embodies the above outlined vibration damping apparatus. 
An additional object of the invention is to provide a vibration damping 
apparatus which occupies a minimal amount of space between the output 
element of an engine and the input element of a variable speed 
transmission in a motor vehicle. 
Another object of the invention is to provide the above outlined apparatus 
with novel and improved means for preventing overheating of certain 
sensitive constituents, particularly of the primary component and of the 
means for transmitting torque between the primary and secondary 
components. 
A further object of the invention is to provide an apparatus which 
constitutes an improvement over and a further development of apparatus of 
the type disclosed in commonly owned U.S. Pat. No. 5,030,167 granted Jul. 
9, 1991 to Jackel for "Apparatus for damping torsional vibrations". 
SUMMARY OF THE INVENTION 
The invention is embodied in an apparatus for damping vibrations in a power 
train between an engine and a transmission in a vehicle. The improved 
apparatus comprises at least two components which are rotatable relative 
to each other about a common axis and include a first component 
connectable with the engine (e.g., with the crankshaft of an internal 
combustion engine) and a second component which is connectable with the 
transmission (e.g., with the input shaft of a variable speed 
transmission), and means for transmitting torque between the first and 
second components. The torque transmitting means includes at least one 
torsionally elastic damper and a slip clutch in series with the damper. 
The slip clutch comprises a device which resembles a diaphragm spring and 
serves for transmission of torque between the damper and the slip clutch, 
means for stressing the device in the axial direction of the first and 
second components including two radially offset abutments which flank the 
device and are rotatable with one of the components. The other component 
has a preferably annular chamber which can accommodate the damper and/or 
the slip clutch and is at least partially filled with a viscous fluid 
(e.g., an oil or a paste). The chamber includes a sealed radially 
outermost portion and a radially inner portion, and the device has a 
radially outer portion. The torque transmitting means further comprises a 
diaphragm type seal for the radially inner portion of the chamber and a 
torque transmitting disc. The disc and the seal are interposed between the 
one component and the radially outer portion of the device. 
The two components preferably constitute the flywheels of a composite 
flywheel. 
It is presently preferred to employ a diaphragm seal and/or a disc which is 
resilient in the axial direction of the two components. The seal is or can 
be axially stressed between the disc and the one component. A friction 
lining (e.g., a friction ring) can be interposed between the device and 
the radially outer portion of the disc. The seal can extend radially 
outwardly beyond the disc. 
The apparatus can further comprise at least one antifriction bearing 
between the first and second components, and one of the two abutments can 
be provided with means for maintaining the at least one bearing in a 
predetermined position as seen in the axial direction of the first and 
second components. Such maintaining means can comprise an annular disc. 
The torque transmitting means can further comprise means (e.g., one or more 
rivets) for connecting the seal and the disc to the one component. Such 
rivet or rivets can be used to connect the aforementioned annular disc 
(maintaining means), the radially inner portion of the device, the seal 
and the disc to the one component. 
The at least one antifriction bearing preferably comprises a first race, a 
second race and at least one annulus of spheres, barrels or other suitable 
rolling elements between the two races. The apparatus can further comprise 
an enclosure which confines one of the races and has portions extending 
substantially radially of the two components and overlying the other race, 
and an energy storing member (e.g., a diaphragm spring) which reacts 
against the disc and bears against one portion of the enclosure. The one 
race is preferably an outer race which surrounds the other race of the at 
least one antifriction bearing. 
The disc and/or the seal can extend radially inwardly beyond the radially 
inner portion of the device and radially inwardly beyond the 
aforementioned maintaining means of the one abutment. 
The torque transmitting means can further comprise means for coupling the 
disc to the seal. Such coupling means can comprise at least one male 
coupling member extending substantially in the axial direction of the two 
components, and at least one female coupling member having a socket for 
the at least one male coupling member. One of the male and female coupling 
members is provided on the disc, and the other of the male and female 
coupling members is provided on the seal. 
The one abutment can comprise first and second disc-shaped portions which 
flank the radially inner portion of the device. The torque transmitting 
means of such apparatus can further comprise means for connecting the two 
disc-shaped portions of the one abutment to each other. These disc-shaped 
portions of the one abutment are or can be axially offset relative to the 
other abutment so that the device is stressed axially of the two 
components between the two disc-shaped portions and the other abutment. 
The torque transmitting means of such apparatus can further comprise means 
for axially movably but non-rotatably coupling the disc to one of the 
disc-shaped portions, and such coupling means can comprise at least one 
male coupling member extending substantially axially of the two components 
and at least one female coupling member having a socket for the at least 
one male coupling member. One of these male and female coupling members is 
provided on the disc, and the other of the male and female coupling 
members is provided on the one disc-shaped portion of the one abutment. 
One of the two disc-shaped portions can include means (such as the 
respective coupling member or members) for centering the device. 
The seal can extend radially beyond one of the two disc-shaped portions 
which form part of the one abutment and is preferably disposed between the 
one component and the one disc-shaped portion. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved vibration 
damping apparatus itself, however, both as to its construction and its 
mode of operation, together with additional 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 drawing.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring first to FIG. 1, there is shown an apparatus 1 which can be 
utilized in the power train of a motor vehicle to damp vibrations between 
the output element (e.g., a crankshaft) of an internal combustion engine 
and the input element (e.g., a shaft) of a variable speed transmission in 
the vehicle. The arrangement is preferably such that an engageable 
friction clutch is interposed between the apparatus of FIG. 1 and the 
input shaft of the transmission. Reference may be had, for example, to 
commonly owned U.S. Pat. No. 4,723,463 granted Feb. 9, 1988 to Reik et al. 
for "Assembly for taking up and compensating for torque-induced shocks" 
which shows an engine, the output element of the engine, a variable speed 
transmission and its input element, as well as a friction clutch with a 
clutch plate mounted on the input element of the transmission. 
The vibration damping apparatus 1 of FIG. 1 comprises a composite flywheel 
2 which has a plurality of coaxial rotary components. FIG. 1 shows two 
components 3, 4 each of which can be said to constitute a flywheel. The 
component 3 is connectable to the output element of the engine by one or 
more screws, bolts or other suitable fasteners (one shown by broken lines, 
as at 50), and the component 4 is connectable to the cover or housing of 
the friction clutch. As mentioned above, the clutch plate of the friction 
clutch can transmit torque to the input element of the variable speed 
transmission. 
The apparatus 1 further comprises an assembly or means for transmission of 
torque between the components 3, 4 of the composite flywheel 2, and such 
torque transmitting means comprises at least one torsionally elastic 
damper 5 (FIG. 1 shows a single damper) and at least one slip clutch 18 
(FIG. 1 shows a single slip clutch) in series with the damper 5. The 
damper 5 is designed to permit but to yieldably oppose a certain angular 
displacement of the component 4 relative to the component 3 and/or vice 
versa. An antifriction roller bearing 6 is installed between the radially 
inner portions of the components 3 and 4. 
The radially outer portion of the component 3 constitutes a housing 
including two sheet-metal sections or walls 8, 9 and defining an annular 
chamber 7 which is at least partially filled with a viscous fluid 51, 
e.g., a lubricant having the consistency of oil or that of a paste or 
grease). The damper 5 is installed in the radially outermost portion or 
compartment 40 of the chamber 7. Such radially outermost portion of the 
chamber 7 is sealed by a welded seam 10 between the abutting faces of the 
sections or walls 8 and 9. Thus, the seam 10 performs the dual function of 
fixedly connecting the sections 8, 9 to each other and of sealing the 
compartment 40 from the surrounding atmosphere. 
The section 8 of the housing for the chamber 7 is adjacent the engine when 
the apparatus 1 is installed in the power train between the engine and the 
transmission of a vehicle, and this section includes a centrally disposed 
protuberance 11 extending toward the transmission and being surrounded by 
the inner race 6b of the antifriction bearing 6. The outer race 6a 
surrounds the inner race 6b of the bearing 6, and such bearing further 
comprises at least one annulus (only one shown) of spherical, 
barrel-shaped, needle-shaped or otherwise configurated rolling elements. 
FIG. 1 shows a single spherical rolling element 6c. A washer-like retainer 
12 is secured to the protuberance 11 and overlies the radially inner 
portion of the inner race 6b to prevent any rightward axial movements of 
the bearing 6. The retainer 12 can be secured to the protuberance 11 by 
the aforementioned fasteners 50 which secure the component 3 to the output 
element of the engine. 
The section 9 of the housing for the chamber 7 of the component 3 has an 
external ring-shaped shoulder 13 which is surrounded by a ring-shaped 
starter gear 14'. This gear is welded or otherwise fixedly secured to the 
section 9, as at 14a. 
The radially inner portion of the annular chamber 7 between the sections 8, 
9 of the housing which forms part of the component 3 is sealed by a 
diaphragm type seal 14 (hereinafter called seal or diaphragm seal) which 
extends radially outwardly toward and is overlapped by and is in sealing 
engagement with the radially innermost portion 9a of the section 9. The 
seal 14 is adjacent the respective side of the component 4 and extends 
radially inwardly all the way to the antifriction bearing 6. 
The slip clutch 18 is also installed in the chamber 7 of the component 3, 
the same as a friction generating device 15 which operates between the 
components 3, 4 and is disposed between the radially inner portion 8a of 
the section 8 and the antifriction bearing 6. The illustrated friction 
generating device 15 surrounds the protuberance 11 which latter is of one 
piece with or is rigidly affixed to the radially inner portion 8a of the 
section 8. 
The torque transmitting output element of the damper 5 is a flange-like 
metallic device 16 which resembles a diaphragm spring and has a radially 
inner or main portion 17 constituting the input element of the slip clutch 
18. The latter is designed to determine the maximum torque which can be 
transmitted between the components 3, 4 of the composite flywheel 2, i.e., 
the maximum torque which can be transmitted between the output element of 
the engine and the input element of the variable speed transmission when 
the friction clutch between the component 4 and the input element of the 
transmission is engaged. The connection between the slip clutch 18 and the 
component 4 is a force-locking connection. 
The device 16 is installed between two abutments 19, 20 which are offset 
relative to each other in the radial direction of the composite flywheel 
2. Thus, the abutment 19 is nearer to and the abutment 20 is more distant 
from the common axis of the components 3, 4 and the flywheel 6. The 
abutments 19, 20 cooperate to stress the device 16 in the axial direction 
of the composite flywheel 2. Thus, when properly installed between the 
components 3 and 4, the diaphragm spring like device 16 is flat or 
exhibits a less pronounced conicity than in unstressed condition prior to 
its mounting in the vibration damping apparatus 1. 
The device 16 comprises the aforementioned radially inner or main portion 
17 and a set of substantially radially outwardly extending arms or prongs 
21 which alternate with the energy storing elements 41 (preferably in the 
form of coil springs) of the damper 5 in the compartment 40 of the annular 
chamber 7. When the vibration damping apparatus 1 is properly assembled, 
the radially outer part 17a of the main portion 17 bears against the 
abutment 20 (which forms part of the component 4), and the radially inner 
part 17b of the main portion 17 is located between the abutment 19 and a 
diaphragm-like disc 29 of the slip clutch 18. The radially inner part 17b 
of the main portion 17 of the device 16 then reacts against the abutment 
19. The abutment 19 includes a disc-shaped radially outer portion 22 which 
is actually engaged by the radially inner part 17b of the main portion 17, 
and a radially inner portion 23 which is secured to the component 4 by a 
set of connecting means in the form of rivets 24 (only one shown in FIG. 
1). The radially inner portion 23 of the abutment 19 can be said to 
constitute or resemble an annular disc and serves as a means for 
maintaining the antifriction bearing 6 in a predetermined axial position 
relative to the protuberance 11 of the component 3. This bearing extends 
into a ring-shaped recess in the radially inner portion of the component 
4. The rivets 24 serve as a means for connecting the component 4 with the 
radially inner portion 23 of the abutment 19, with the disc 29 of the slip 
clutch 18 and with the diaphragm seal 14 for the radially inner portion of 
the annular chamber 7. The portions 22, 23 of the abutment 19 are axially 
offset relative to each other and are integral with a substantially 
S-shaped intermediate portion 25 which is adjacent the internal surface of 
main portion 17 of the device 16. The portion 25 can be said to constitute 
a means for centering the device 16 between the section 8 of the component 
3 and the component 4. A friction ring 26 is installed between the 
radially inner part 17 b of the main portion 17 and the radially outer 
portion 22 of the abutment 19. 
As mentioned above, the other abutment 20 for the device 16 forms part of 
the component 4 and is located radially outwardly of the abutment 19. It 
is presently preferred to provide the component 4 with an abutment 20 
which consists of two or more arcuate sections or portions together 
forming a composite ring-shaped projection and alternating with 
substantially radially extending passages 20a confronting the right-hand 
side of the diaphragm seal 14. The purpose of the passages 20a is to 
permit circulation of cool atmospheric air which withdraws heat from the 
component 4 and thus prevents overheating of the seal 14 and of the 
contents (including 5, 15, 18, 51) of the annular chamber 7. The component 
4 is heated during engagement or disengagement of the friction clutch, 
namely when the friction surface 28 at the right-hand side of the 
component 4 slides relative to the adjacent friction lining of a clutch 
plate forming part of the friction clutch and having a hub mounted on and 
serving to rotate the input element of the variable speed transmission 
when the friction clutch is engaged. 
The passages 20a between the sections or portions of the abutment 20 
communicate with substantially axially parallel holes or ports 27 which 
are provided in the component 4 radially inwardly of the friction surface 
28, as well as with a clearance or gap 33 between the outer side of the 
section 9 and the adjacent radially outer portion of the component 4. 
The slip clutch 18 further comprises a friction lining 30 which is 
installed between the radially outer part 17a of main portion 17 of the 
device 16 and the adjacent radially outermost portion of the diaphragm 
like disc 29. The device 16 can turn relative to the component 4 and/or 
vice versa when the main portion 17 is compelled to turn relative to the 
friction lining 30 (if the latter is affixed (e.g., bonded) to the disc 
29) or when the disc 29 can turn relative to the lining 30 (if the latter 
is bonded to the main portion 17 of the device 16). 
As already mentioned hereinabove, the radially inner portions of the disc 
29 and seal 14 are non-rotatably connected to the component 4 by rivets 
24. To this end, the disc 29 and the seal 14 extend radially inwardly 
beyond the main portion 17 of the device 16 and overlie the right-hand 
side of the radially inner portion 23 of the abutment 19. 
The disc 29 and the diaphragm spring 14 are preferably made of spring steel 
and are preferably stressed during installation in the apparatus 1. An 
advantage of a springy disc 29 and of a springy seal 14 is that these 
parts do not undergo permanent deformation when the assembly of the 
apparatus 1 is completed. The radially outermost portion of the seal 14 
bears against and thus sealingly engages the radially innermost portion 9a 
of the section 9. It is presently preferred to employ a seal 14 which is 
thinner than the disc 29. For example, the thickness of the seal 14 can be 
between 0.15 and 0.25 mm, and the thickness of the disc 29 can be between 
0.4 and 0.7 mm. The relatively thin seal 14 is readily deformable in the 
axial direction of the composite flywheel 2; this ensures that the 
radially inner portion 9a of the section 9 and the radially outermost 
portion of the seal 14 generate a relatively small amount of friction when 
the component 3 (i.e., the section 9) is caused to turn relative to the 
component 4 (i.e., the seal 14) and/or vice versa. 
The disc 29 and the friction lining 30 transmit at least a certain amount 
of torque, namely the torque between the radially outer part 17a of the 
main portion 17 of the device 16 and the component 4 of the composite 
flywheel 2. The disc 29 shields the seal 14 from deformation by the axial 
force which is transmitted by the main portion 17 of the device 16. The 
seal 14 is located and can be clamped between the abutment 20 of the 
component 4 and the disc 29. The rivets 24 (which non-rotatably connect 
the disc 29 with the component 4) ensure that the seal 14 need not 
participate in transmission of torque so that the seal is not subjected to 
any torsional or like deforming stresses which could affect its sealing 
action. The feature that the seal 14 is shielded from torsional and other 
non-axial stresses ensures the establishment of a highly satisfactory 
sealing action between the radially outermost portion of the seal 14 and 
the radially innermost portion 9a of the section 9. 
The inclination of that portion of the disc 29 which is adjacent the 
right-hand side of the main portion 17 of the device 16 is different from 
the inclination of the adjacent portion of the seal 14. This results in 
the establishment of a narrow wedge-like clearance or space 31 which 
narrows radially outwardly. Moreover, the left-hand side of the disc 29 is 
slightly spaced apart from the main portion 17 of the device 16 so that 
these parts also define a wedge-like clearance or gap 32. The 
aforementioned clearance or gap 33 (which communicates with the passages 
20a) is open to the atmosphere in the region of the starter gear 14 so 
that streams of cooling air can circulate from the ports 27, through the 
passages 20a and through the clearance 33 when the component 4 is in 
rotary motion. At such time, the component 4 draws cool atmospheric air 
into its ports 27. The ports 27, the passages 20a and the clearances 31, 
32, 33 ensure that the annular chamber 7 and the viscous fluid 51 therein 
are not affected by heat which is generated at the friction surface 28 of 
the component 4 during engagement or disengagement of the friction clutch, 
i.e., when the surface 28 moves relative to the adjacent friction lining 
of the clutch plate forming part of the friction clutch. The friction 
lining 30 (e.g., a friction ring) is preferably made of a material which 
is a poor conductor of heat; this also contributes to satisfactory thermal 
insulation of the component 3 from the component 4. 
Prior to being installed between the device 16 and the component 4, the 
radially outer portions of the seal 14 and disc 29 constitute hollow 
conical frusta. At such time, the radially outermost portions of the parts 
14 and 29 are located to the right of the positions which are shown in 
FIG. 1. Deformation of the seal 14 and disc 29 take place in response to 
the application of rivets 24. The same holds true for the resilient 
diaphragm spring like device 16. 
The outer race 6a of the antifriction bearing 6 is confined in a two-piece 
enclosure 34 which has installed in the aforementioned annular recess of 
the component 4 and includes portions 35 which overlie the respective end 
faces of the inner race 6b radially outwardly of the retainer 12. The 
enclosure 34 serves as a means for thermally insulating the bearing 6 from 
the component 4. Energy storing members in the form of diaphragm springs 
36 are provided to bias the portions 35 of the enclosure 34 against the 
respective end faces of the inner race 6b. This ensures that the lubricant 
for the rolling elements 6c is confined in the annular space between the 
races 6a and 6b. 
The radially innermost portion 37 of the disc 29 extends radially inwardly 
beyond the portions 22, 25, 23 of the abutment 19 and overlaps the 
left-hand diaphragm spring 36; the left-hand diaphragm spring 36 reacts 
against the portion 37 and bears against the respective radially inwardly 
extending portion 35 of the enclosure 34. 
The radially innermost portion of the seal 14 also extends radially 
inwardly of the abutment 19 and has axially parallel male coupling members 
in the form of prongs 38 which are received in complementary sockets 39 of 
the radially innermost portion 37 of the disc 29. The portion 37 can be 
said to constitute a female coupling member which cooperates with the male 
coupling members or prongs 38 to ensure that the seal 14 and the disc 29 
cannot turn relative to each other. The radially innermost portion of the 
seal 14 is preferably provided with radially extending slots which 
alternate with the male coupling members 38, and such male coupling 
members are simply bent out of the general plane of the seal 14 so that 
they can enter the adjacent sockets 39 when the radially innermost 
portions of the seal 14 and disc 29 are placed next to each other 
preparatory to application of the rivets 24. The just described coupling 
between the radially innermost portions of the seal 14 and disc 29 
constitutes a reliable form-locking connection which facilitates accurate 
positioning of these parts relative to each other as well as relative to 
the abutment 19, device 16 and abutment 20 of the component 4 prior to 
application of the rivets 24. 
The radially outermost portion or compartment 40 of the chamber 7 is 
subdivided into arcuate portions, one for each of the several arcuate 
energy storing coil springs 41 of the damper 5. Subdivision of the 
compartment 40 into arcuate portions for discrete coil springs 41 can be 
effected by providing the sections 8, 9 with inwardly extending depressed 
portions (one shown at 9b) which provide room for the radially outwardly 
extending legs 21 of the device 16. The projections (including that shown 
at 9a) and the arms 21 alternate with the springs 41 so that each such 
spring is caused to store energy when the sections 8, 9 of the component 3 
are caused to turn relative to the device 16 and/or vice versa. The manner 
of stressing the springs of a damper in an annular chamber of one flywheel 
of a composite flywheel in a vibration damping apparatus for use in the 
power train between the engine and the transmission of a motor vehicle is 
fully described and shown in numerous United States and foreign patents 
and in numerous United States and foreign patent applications of the 
assignee of the present application. 
The compartment 40 of the annular chamber 7 contains arcuate shrouds or 
shields 42 which are installed between the radially outermost portions of 
the springs 41 and the adjacent portions of internal surfaces of the 
sections 8, 9. The hardness of the material of the shrouds 42 (each 
arcuate portion of the compartment 40 can contain a discrete shroud) 
preferably exceeds the hardness of the material of the sections 8, 9. The 
purpose of such shrouds is to shield the sections 8 and 9 from extensive 
wear when the apparatus 1 is in actual use, i.e., when the component 3 is 
rotated and the springs 41 tend to move radially outwardly under the 
action of centrifugal force. The quantity of viscous fluid 51 in the 
chamber 7 is selected in such a way that at least a portion of each spring 
41 is contacted by viscous fluid when the component 3 is caused to rotate 
so that the viscous fluid is forced into the radially outermost portion 40 
of the chamber 7 under the action of centrifugal force. 
The housing including the sections 8, 9 and the springs 41 can be 
constructed and mounted, and the damper 5 and certain other units of the 
apparatus 1 can operate, in a manner as disclosed in the aforementioned 
published German patent application No. 39 09 892. 
An important advantage of the improved vibration damping apparatus is that 
the radially inner portion of the chamber 7 can be sealed by a very thin 
diaphragm seal 14 which is not subjected to the deforming action of the 
diaphragm spring like or flange like torque transmitting device 16. The 
seal 14 is acted upon by the torque transmitting disc 29 which causes it 
to bear upon the radially innermost portion 9a of the section 9 with a 
force that is necessary to confine the viscous fluid 51 in the chamber 7. 
The disc 29 transmits torque between the device 16 and the component 4, 
i.e., such torque need not be transmitted by the seal 14 so that the 
latter is not subjected to any torsional or other stresses which could 
affect its useful life and/or its sealing action at 9a. 
The device 16 is axially stressed in such a way that it bears against the 
ring-shaped friction lining 26 rather than against the median portion of 
the disc 29 (note the clearance or gap 32). Thus, though the disc 29 
receives torque from the device 16 via preferably ring-shaped friction 
lining 30, it need not take up the axial stresses which are applied by the 
radially inner portion 17b of the main portion 17. This contributes to 
compactness of the vibration damping apparatus because the seal 14 as well 
as the disc 29 can be made of thin or extremely thin spring steel sheet 
stock or a similar resilient material. 
Though it is possible, to modify the design of the improved vibration 
damping apparatus by mounting the abutment 19 on the component 3, it is 
presently preferred to provide the chamber 7 in that component (3) of the 
composite flywheel 2 which is connectable to the output element of the 
engine. 
The device 16 can be modified in a number of ways without departing from 
the spirit of the invention. For example, the recesses between the arms 21 
(each such recess receives one of the coil springs 41) can be replaced by 
windows, i.e., the arms 21 can constitute partitions between a set of 
neighboring windows each of which is dimensioned to receive a coil spring 
or another suitable energy storing element of the damper 5 or an analogous 
damper. The main portion 17 of the device 16 preferably constitutes a 
one-piece washer-like (ring-shaped body). 
The component 3 constitutes the input element of the damper 5, i.e., the 
inwardly extending portions (see the portion 9b) of its walls 8, 9 can 
directly engage and stress the springs 41 of the damper. The device 16 
constitutes the output element of the damper 5 and connects the latter in 
series with the slip clutch 18 including the disc 29. The slip clutch 18 
established a force-locking connection between the device 16 and the 
component 4. 
The utilization of a resilient disc 29 and of a resilient seal 14 
constitutes an additional advantageous feature of the improved apparatus. 
Thus, by utilizing parts 14 and 29 which are resilient in the axial 
direction of the components 3 and 4, one ensures that neither of these 
parts undergoes permanent deformation during assembly of the vibration 
damping apparatus 1 as well as that such parts remain resilient when the 
apparatus is in actual use. Permanent deformation of the seal 14 would 
affect its sealing action. This seal is installed between the disc 29 and 
the component 4 and is stressed in the axial direction to ensure the 
establishment of reliable and long-lasting sealing engagement with the 
radially innermost portion 9a of the section 9 of the housing for the 
chamber 7. By coupling the seal 14 for rotation with the disc 29, one 
ensures that the seal 14 need not take up any torsional or other stresses 
which would adversely affect its shape and hence its sealing action. More 
specifically, the seal 14 is subjected only to axial stresses but is not 
acted upon in the circumferential direction of the components 3 and 4. 
The purpose of the friction lining 30 is to ensure the establishment of an 
optimal moment of friction between the device 16 and the component 4, 
i.e., to ensure highly predictable operation of the slip clutch 18. The 
lining 30 can constitute a one-piece ring or it can be assembled of 
several discrete sections. 
The feature that the seal 14 extends radially outwardly beyond the disc 29 
is desirable and advantageous because this ensures that the magnitude of 
friction between the radially outermost portion of the seal 14 and the 
radially innermost portion 9a of the section 9 is within an optimal range, 
i.e., that the wear upon the seal 14 during angular movement relative to 
the section 9 and/or vice versa is within acceptable limits. 
The rivets 24 are preferably installed close to the outer race 6a of the 
antifriction bearing 6. As mentioned above, these rivets perform a number 
of important functions, namely of connecting the component 4 with the 
abutment 19, with the disc 29 and with the seal 14. At the same time, the 
rivets 24 enable the abutment 19 to cooperate with the abutment 20 in 
maintaining the device 16 in axially stressed condition as well as of 
axially stressing the disc 29 and the seal 14, of ensuring the 
establishment of optimal frictional engagement between the friction lining 
30 and the device 16 (or disc 29), and the establishment of optimal 
frictional engagement between the seal 14 and the section 9. 
FIG. 2 shows a portion of a modified vibration damping apparatus 101. All 
such constituents of the apparatus 101 which are identical with or clearly 
analogous to corresponding constituents of the apparatus 1 of FIG. 1 are 
denoted by similar reference characters plus 100. The radially inner 
portion 116a of the main portion of the diaphragm spring like torque 
transmitting device 116 is disposed between the disc-shaped radially outer 
portion 122 of the abutment 119 and the disc-shaped radially outer portion 
143a of a washer 143 which can be said to constitute a separately produced 
part of the composite abutment 119. The means for fixedly connecting the 
washer 143 to the other (main) part of the abutment 119 includes rivets 
144 which preferably form an annulus and alternate with rivets 124 for 
connection of the abutment 119 to the second component 104 of the 
composite flywheel 102. The rivets 144 render it possible to secure the 
washer 143 to the main part of the composite abutment 119 and to 
simultaneously assemble the disc-shaped portions 122, 143a of such 
composite abutment with the device 116 to thus obtain a preassembled unit 
which can be more readily assembled with the component 104 before the 
latter is assembled with the component 103 and bearing 106. 
When the making of the subassembly is completed, i.e., when the rivets 144 
connect the washer 143 with the main portion of the composite abutment 119 
and the radially inner portion 116a of the device 116 is located between 
the disc-shaped portions 122 and 143a, that part of the device 116 which 
is located radially outwardly of the disc-shaped portions 122, 143a 
assumes a shape which is shown by broken lines, as at 145. At such time, 
the device 116 is maintained in partly stressed condition. Such initial 
stressing of the device 116 (during making of the subassembly including 
the composite abutment 119 and the device 116) ensures that the device 116 
need not undergo extensive additional axial stressing during assembly of 
the component 103, namely during making of the welded seam 110 which 
connects the housing sections 108, 109 to each other and simultaneously 
seals the radially outermost portion or compartment 140 of the annular 
chamber 107. In other words, the section 109 need not subject the device 
116 to a pronounced axial stress during attachment of the section 109 to 
the section 108 of the component 103. Initial stressing of the device 116 
(i.e., while the device 116 assumes the shape 145 as a result of making of 
the subassembly including the composite abutment 119 and the device 116) 
suffices to ensure convenient introduction of the arms 121 into the 
compartment 140 of the chamber 107 so that the arms 121 alternate with the 
coil springs 141 of the torsionally elastic damper 105 in the chamber 107. 
The radially outer portions of the springs 141 in the compartment 140 are 
adjacent arcuate shrouds 142, at least one in each arcuate portion of the 
compartment 140. The arms 121 of the device 116 facilitate proper 
installation of the springs 141 and/or shrouds 142 in the respective 
arcuate portions of the compartment 140. This renders it possible to 
expedite the assembly of the vibration damping apparatus 101. 
The radially innermost portion 122a of the composite abutment 119 serves to 
maintain the bearing 106 in a predetermined axial position relative to the 
central axial protuberance 111 of the component 103. This radially 
innermost portion 122a bears against the adjacent portion 135 of the 
enclosure 134 for the outer race 106a of the bearing 106. The latter is 
but need not be identical with or similar to the antifriction bearing 6 of 
FIG. 1. The radially innermost portion 122a of the composite abutment 119 
can carry the left-hand diaphragm spring 136 which bears against the 
adjacent radially inwardly extending portion 135 of the enclosure 134. To 
this end, the internal surface of the portion 122a is provided with an 
annular shoulder 122b for the radially outermost portion of the adjacent 
diaphragm spring 136. A thin washer 138 is provided at the left-hand side 
of the innermost portion 122a to overlie the radially outermost portion of 
the diaphragm spring 136 so that the latter is compelled to contact the 
shoulder 122b and is properly centered and otherwise positioned prior to 
attachment of the composite abutment 119 to the component 104, i.e., prior 
to application of the rivets 124. This simplifies the assembly of the 
vibration damping apparatus 101. 
The washer 138 can constitute the radially innermost portion of a blank 
(made of thin spring steel sheet stock) which is converted into the 
diaphragm seal 114 for the radially inner portion of the chamber 107. The 
radially outermost portion of the washer 138 is clamped between the washer 
143 and the radially innermost portion 122a of the composite abutment 119. 
The radially outermost port of the diaphragm seal 114 bears against the 
radially innermost portion 109a of the substantially radially extending 
housing section 109. The radially inner portion 114a of the seal 114 is 
clamped between the adjacent radially extending surface 104a of the 
component 104 and the washer 143 of the composite abutment 119. 
The disc 129 is installed between the seal 114 and the device 116, and its 
radially innermost portion includes radially inwardly extending male 
coupling member 129a in the form of prongs, lugs or teeth which extend 
into radially extending sockets provided in the radially outermost portion 
or female coupling member 143b of the washer 143. The form-locking 
connection or coupling including the male coupling member 129a and the 
female coupling member 143b ensures that the disc 129 shares the angular 
movements of the composite abutment 119 but is movable axially of the 
washer 143. Such coupling further serves as a means for centering the disc 
129 on the washer 143 of the composite abutment 119. The male coupling 
members 129a serve to transmit to the washer 143 (and hence to the 
composite abutment 119 and component 104) that portion of torque which is 
being transmitted by the disc 129. 
A friction lining 126 is installed between the radially outermost portion 
122 of the abutment 119 and the adjacent side of the device 116. A further 
friction lining 130 is disposed between the device 116 and the disc 129. 
The shape of the disc 129 and seal 114 in the fully assembled vibration 
damping apparatus 101 departs, in unstressed condition. When the disc 129 
and the seal at least slightly, from the shape which these parts assume 
114 are unstressed or are not fully stressed, their portions between the 
abutment 120 of the component 104 and the device 116 (while the device 116 
is free to assume the shape 145) are substantially or exactly parallel to 
the adjacent portion of the device 116. 
The transfer of heat from the component 104 to the component 103 and its 
chamber 107 is reduced to an acceptable value by streams of air which are 
caused to enter the ports 127 of the component 104, thereupon flow through 
the radial passages 120a between the portions of the abutment 120, and 
leave the apparatus 101 through the clearance or gap 133. 
An advantage of the subassembly which includes the composite abutment 119 
(with its disc-shaped portion or washer 143), the rivets 144 and the 
device 116 is that the latter is subjected to some axial stressing prior 
to further assembly of the vibration damping apparatus 101. Thus, and as 
already explained hereinabove, the making of the welded seam 110 between 
the sections 108, 109 of the component 103 can be carried out without 
extensive additional stressing of the device 116 by the section 109. This 
simplifies the assembly of the component 103, i.e., the establishment of a 
rigid connection between the sections 108 and 109. In addition, the 
subassembly including the composite abutment 119, the rivets 144 and the 
device 116 facilitates rapid and predictable assembly of the damper 105, 
i.e., the installation of springs 141 and shroud 142 in the corresponding 
portions of the compartment 140, i.e., in the radially outermost portion 
of the annular chamber 107. 
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 my contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the appended 
claims.