Damper disk assembly

A clutch disk assembly 1 includes an output rotary member 4, an intermediate member 3, first springs 7, a damper 8, plates 12 and 13, and third springs 5. The intermediate member 3 is disposed radially outside the output rotary member 4. The first springs 7 are arranged between the output rotary member 4 and the intermediate member 3, and are circumferentially compressed when a hub and the intermediate member 3 rotate relatively to each other in a first stage of relative rotary displacement. A damper 8 is disposed between the output rotary member 4 and the intermediate member 3, and includes second springs 10 that are not compressed in the first stage of relative rotary displacement but are compressed in a second stage of relative rotary displacement. The torsion angle corresponding to the second stage is larger than a torsion angle corresponding to the first stage. The plates 12 and 13 are arranged on the axial side of the intermediate member 3. The third springs 5 circumferentially and elastically couple the intermediate member 3 to the plates 12 and 13. The above configuration suppresses a jumping phenomenon between the first and second stages.

BACKGROUND OF THE INVENTION 
A. Field of the Invention 
The invention relates to a damper disk assembly, and particularly a damper 
disk assembly for transmitting a torque and for absorbing and damping a 
torsional vibration. 
B. Description of the Background Art 
A clutch disk assembly used in a clutch mechanism in, for example, an 
automotive vehicle has a clutch function for releasable engagement with a 
flywheel, and also has damper capabilities that allow it to dampen 
torsional vibration. The clutch disk assembly includes a clutch coupling 
portion (friction surface portions), input plates fixed to the clutch 
coupling portion, a hub disposed radially inside the input plates, and 
elastic members elastically coupling the input plates to a flange of the 
hub in a circumferential direction. When the clutch coupling portion is 
biased toward the flywheel, torque is transmitted from the flywheel. 
Torque is transmitted to the hub via the elastic members, and then is 
output to a shaft extending from the transmission. When variations in 
torque of the engine are transmitted to the clutch disk assembly, relative 
rotation occurs between the input plates and the hub. As a result, the 
elastic members are circumferentially compressed. The clutch disk assembly 
further includes a friction mechanism that is arranged between the input 
plates and the hub for generating a frictional resistance when the 
relative rotation occurs therebetween. The friction mechanism includes a 
plurality of washers and a biasing member. 
In a clutch disk assembly of a hub-separated type, the flange is separated 
from the hub, and is used as an intermediate member. The hub and the 
intermediate member are circumferentially coupled together by elastic 
members having a lower rigidity. In this clutch disk assembly, a maximum 
torsional angle between the input plates and the hub can be increased, and 
torsional characteristics can have first and second stages of low and high 
rigidities, respectively. 
In a torsional vibration system defined by the clutch disk assembly, the 
transmission and other members, normal vibrations in rotation speed of the 
engine continuously cause collisions between gear teeth of connecting 
gears in the transmission, and thereby cause noises. For reducing the 
torsional vibration and associated gear noises, it is necessary to provide 
the elastic members with a reduced spring constant so that there is a low 
rigidity in the first dampening stage. However, for damping the torsional 
vibration such as a low frequency vibration, which causes a much larger 
angle of relative rotation in the clutch disk assembly, it is necessary to 
increase a spring constant of the elastic members functioning in the 
second stage of dampening. In the conventional device having such 
characteristics, a jumping phenomenon occurs. In other words, the 
operation angle jumps over the region in the first stage and enters the 
second stage, for example, when a torque variation is supplied during 
idling. The jumping phenomenon is caused by oscillations in the 
transmission of the inertia with respect to, the elastic members that are 
provided in the clutch disk assembly for the second stage of the dampening 
characteristics. This causes gear collision to a much higher extent than 
the normal gear collision due to excessive rotational variations. 
SUMMARY OF THE INVENTION 
One object of the present invention is to suppress a jumping phenomenon 
that sometimes occurs between first and second stages of dampening in a 
damper mechanism. 
Another object of the present invention is to provide a simple structure 
that can provide an intermediate rigidity between stages of the torsion 
vibration dampening in a damper mechanism. 
In accordance with one aspect of the present invention, a damper disk 
assembly includes a hub and first circular plate member disposed radially 
outside the hub. A first elastic member is operably disposed between the 
hub and the first circular plate member. The first elastic member is 
configured for circumferential compression in response to relative rotary 
displacement between the hub and the first circular plate member in a 
first stage of the relative rotary displacement. A damper is disposed 
between the hub and the first circular plate member. The damper has a 
second elastic member configured such that the second elastic member 
undergoes compression in a second stage of the relative rotary 
displacement but generally does not undergo compression in the first stage 
of the relative rotary displacement. A torsion angle corresponding to the 
second stage is larger than a torsion angle corresponding to the first 
stage. A second circular plate member is axially opposed to the first 
circular plate member and a third elastic member circumferentially and 
elastically couples the first and second circular plate members together. 
The third elastic member has a spring constant larger than that of the 
first elastic member and that of the second elastic member. 
In the above damper disk assembly, the first elastic member is 
circumferentially compressed between the hub and the first circular plate 
member when the hub and the second circular plate member rotate relatively 
to one another through a small torsion angle. When the torsion angle 
increases, the second elastic member is circumferentially compressed 
between the hub and the first circular plate member so that 
characteristics of a high rigidity are exhibited. When the torsion angle 
further increases, the third elastic member is circumferentially 
compressed between the first and second circular plate members so that 
characteristics having a further high rigidity are exhibited. Since the 
damper disk assembly described above can provide an intermediate rigidity 
owing to the operation of the second elastic member between the operations 
of the first and second third elastic members, the jumping phenomenon due 
to the vibration during idling can be suppressed. 
Preferably, the damper further includes an intermediate member engaged with 
the second elastic member and is circumferentially spaced from the hub by 
the first torsion angle. 
Accordingly, when the first elastic member is compressed through the first 
torsion angle, the second elastic member comes into contact with the 
intermediate member, and the second elastic member is circumferentially 
compressed thereafter. 
Preferably, the first circular plate member supports the circumferentially 
opposite ends of the second elastic member. The intermediate member 
supports circumferentially opposite ends of the second elastic member. The 
intermediate member is circumferentially spaced from the hub by the first 
torsion angle. 
Preferably, a gap corresponding to the second torsion angle is larger than 
a gap corresponding to the first torsion angle. The gap corresponding to 
the second torsion angle is formed circumferentially between the hub and 
the first circular plate member. 
Accordingly, when the torsion angle between the hub and the second circular 
plate member exceeds the second torsion angle, the second elastic member 
is no longer compressed, and thereafter the third elastic member will be 
compressed between the intermediate member and the second circular plate 
member. In the damper disk assembly, since the second elastic member is 
not compressed in the third stage, breakage or damage to the second 
elastic member can be suppressed. 
Preferably, the hub is provided with a plurality of first teeth that extend 
radially outward. The intermediate member is provided at its inner 
periphery with a plurality of second teeth circumferentially spaced from 
the first teeth by the first torsion angle, respectively. The first 
circular plate member is provided at its inner periphery with a plurality 
of third teeth circumferentially spaced from the first teeth by a second 
torsion angle, respectively, and the second torsion angle is larger than 
the first torsion angle. 
Accordingly, stop portions between the hub and the intermediate member are 
defined by the first and second teeth. Stop portions between the hub and 
the first circular plate member are defined by the first and third teeth. 
Since the stop portions are formed of gear teeth that can come into 
circumferential contact with each other, the structure can be simple. 
Preferably, the intermediate member has a plate-like shape formed with an 
annular portion, and an engagement portions that extends radially outward 
from the annular portion engaging circumferentially opposite ends of the 
second elastic member. The intermediate member further includes a 
plurality of second teeth extending radially inward from the annular 
portion. 
Accordingly, the intermediate member has the plate-like form, and the 
respective portions thereof have bent structures so that the whole 
structure can be simple. 
Preferably, the second elastic member is formed with a pair of springs 
located at axially offset positions for parallel operation between the 
intermediate member and the first circular plate member. 
Since the second elastic member is formed of the pair of springs located at 
the axially shifted positions, a relatively large rigidity can be produced 
in the second stage. 
In accordance with another aspect of the present invention, a damper 
disposed between first member and a second member the first and second 
members being relatively rotatable with respect to one another within a 
predetermined angle. The damper includes a pair of seats that extend 
axially, and engage the first member for allowing transmission of a torque 
therebetween. A pair of elastic members are disposed between the paired 
seats, and located next to each other with respect to an axial direction 
of the first and second members. A plate having an annular portion is 
engaged with the second member for allowing transmission of a torque 
therebetween. A receiver portion extends from the annular portion for 
receiving the pair of seats and the pair of elastic members. 
The damper is formed of the paired seats, the paired elastic members and 
the plate, and thus has a simple structure. In particular, the damper 
includes the paired elastic members at the axially shifted positions, and 
the paired seats are arranged on the circumferentially opposite sides of 
the elastic members. Therefore, the damper can exhibit a relatively high 
rigidity. 
Preferably, the receiver portion is formed with a pair of contact portions 
that contact respective circumferentially outer sides of the seats. 
Therefore, the plate transmits the torque through the paired contact 
portions to the paired seats and the paired elastic members. 
Preferably, the receiver portion has a projecting portion that extends 
radially outward from the annular portion. The projecting portion is 
configured to support the paired seats and the paired elastic members from 
a first axial side thereof. The projecting portion is further formed with 
a pair of contact portions extending axially from the circumferentially 
opposite sides of the projected portion. 
In the damper, the projecting portion extends from the annular portion, and 
the paired contact portions extend from the projecting portion. The paired 
contact portions have simple structures formed, for example, by bending 
them with respect to the projecting portion. 
Preferably, the receiver portion further has a holding portion extending 
axially from the radially outer side of the projected portion and 
supporting radially outer sides of the paired elastic members and the 
paired seats. 
In the damper, the holding portion extends from the projected portion, and 
supports the radially outer sides of the paired elastic members and the 
paired seats. The holding portion has a simple structure formed by bending 
the same with respect to the projected portion. 
Alternatively, a cap is engaged with the first member. The cap is immobile 
toward a second axial side with respect to the first member, and the cap 
supports the second axial sides of the paired elastic members and the 
paired seats. 
In the alternate configuration of the damper, the cap restricts movement of 
the paired elastic members and the paired caps toward the second axial 
side. 
Preferably, the paired contact portions extend over the entire axial length 
of the paired seats and the plate further has a restricting portion 
extending circumferentially from the axial ends of the paired contact 
portions. The plate is disposed on the second axial side with respect to 
the paired elastic members and the paired seats. 
In the damper, the restricting portion restricts the movement of the paired 
elastic members and the paired seats toward the second axial side. The 
restricting portion is formed by bending the same with respect to the 
contact portion, and thus has a simple structure. Further, the paired 
seats, the paired elastic members and the plate in the damper can be 
handled as a preassembly in a cassette form, which allows easy attachment 
to associated elements. 
Preferably, the paired elastic members are coil springs and each of the 
paired seats has a main body extending in the axial direction and fitted 
portions extending from the main body. The fitted portions extend into the 
paired elastic members, respectively. 
In the damper, the coil springs are axially retained by the fitted portions 
of the paired seats, where the paired seats extend into the springs such 
that interference between the coil springs is suppressed. 
The damper according to the present invention is formed of the paired seat, 
the paired elastic members and the plate, and thus has a simple structure. 
In particular, the paired elastic members are located at the axially 
shifted positions, and the paired seats are arranged on the 
circumferentially opposite sides of the elastic member pair. Therefore, 
the damper can exhibit a relatively high rigidity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First Embodiment 
FIGS. 1 and 2 show a clutch disk assembly 1 in accordance with one 
embodiment of the invention. The clutch disk assembly 1 is used in a 
clutch mechanism in an automotive vehicle. A flywheel (not shown) is 
disposed on the left side of the clutch disk assembly 1 in FIG. 1, and a 
transmission (not shown) is disposed on the right side in FIG. 1. In the 
following description, the left side in FIG. 1 is referred to as a "first 
axial side", and the right side in FIG. 1 is referred to as a "second 
axial side". 0--0 in FIG. 1 represents a rotation axis of the clutch disk 
assembly 1. A rotation direction R1 in FIG. 2 is a direction of rotation 
of the flywheel and the clutch disk assembly 1, and a rotation direction 
R2 is a reverse direction. 
The clutch disk assembly 1 is basically formed of an input rotary member 2, 
an intermediate member 3, an output rotary member 4, third springs 5, 
fourth springs 6, second springs 10 and a damper 8. The input rotary 
member 2 is a member receiving a torque from the flywheel (not shown). The 
output rotary member 4 in this embodiment is a hub that is configured for 
connection to the shaft (not shown) of a transmission (not shown) such 
that the output rotary member 4 may slide in an axial direction (along the 
axis 0--0) but rotates together with the shaft. The intermediate member 3 
is disposed between the input rotary member 2 and the output rotary member 
4. The third and fourth springs 5 and 6 are provided for circumferentially 
and elastically coupling the input rotary member 2 and the intermediate 
member 3 together. First springs 7 are provided for circumferentially and 
elastically coupling the intermediate member 3 and the output rotary 
member 4 together. The damper 8 is a mechanism disposed between the output 
rotary member 4 and the intermediate member 3 in parallel with the first 
springs 7, as is more clearly shown in FIG. 1. 
Structures of various portions of the clutch disk assembly 1 will be 
described below more in detail. 
The input rotary member 2 is basically formed of a friction portion 11 
(clutch disk), a first plate 12 and a second plate 13. 
The friction portion 11 is an annular member disposed near a friction 
surface of the flywheel. The friction portion 11 is basically formed of a 
pair of facings and a cushioning plate. 
First and second plates 12 and 13 are circular or annular, and are axially 
spaced apart from each other by a predetermined distance. The outer 
peripheral portions of the first and second plates 12 and 13 are fixed 
together by a plurality of pins 15 that are circumferentially spaced from 
each other. Thereby, the first and second plates 12 and 13 are spaced from 
each other by a constant axial distance, and rotate together as a single 
unit. The cushioning plate is fixed to the outer peripheral portion of the 
first plate 12 by rivets 14. 
The first plate 12 is provided with first receiver portions 19 which are 
circumferentially equally spaced from each other. Each first receiver 
portion 19 shaped to extend in the axial direction (as shown in FIG. 1), 
and includes first contact portions 20 (in phantom lines in FIG. 1) at its 
circumferentially opposite sides. The first contact portions 20 are 
circumferentially opposed to each other. The first plate 12 is also 
provided with a plurality of second receiver portions 21 that are spaced 
apart from one another in the circumferential direction. Each second 
receiver portion 21 is formed to extend slightly toward the first axial 
side, and has second contact portions 22 at circumferentially opposite 
sides thereof (shown in phantom lines in FIG. 1). The second contact 
portions 22 are circumferentially opposed to each other to contact 
opposite ends of the spring 6. 
The second plate 13 is provided with a plurality of first receiver portions 
23 which are circumferentially equally spaced from one another. The first 
receiver portions 23 are formed to correspond to the first receiver 
portions 19, respectively, and each have first contact portions 24 at its 
circumferentially opposite ends thereof. The second plate 13 is further 
provided with a plurality of second receiver portions 25 arranged in the 
circumferential direction. The second receiver portions 25 are formed to 
correspond to the second receiver portions 21, respectively, and each has 
second contact portions 26 at circumferentially opposite ends thereof. The 
first receiver portions 19 and 23 are longer in the circumferential and 
radial directions than the second receiver portions 21 and 25. 
An annular bushing 16 is arranged on the inner periphery of the first plate 
12. The bushing 16 is supported rotatably on the outer peripheral surface 
of a hub 56 of the output rotary member 4. Thereby, the input and output 
rotary members 2 and 4 are radially positioned with respect to each other. 
The bushing 16 is in contact with the surfaces, on the first axial side, 
of a flange 57 and outer teeth 58, as is described below. 
The intermediate member 3 is a circular or annular member disposed axially 
between the first and second plates 12 and 13. The intermediate member 3 
is larger in axial thickness than the first and second plates 12 and 13. 
The intermediate member 3 is provided with circumferentially extending 
first windows or apertures 29 as shown in FIG. 2. The first windows 29 are 
formed to correspond to the first receiver portions 19 and 23 in the 
plates 12 and 13. The intermediate member 3 is further provided with a 
plurality of second windows 30 disposed at space apart locations in the 
circumferential direction. The second windows 30 correspond to the second 
receiver portions 21 and 25. 
The third springs 5 are disposed in the first windows 29. Each third spring 
25 is a combination of large and small coil springs 5a and 5b. The 
circumferentially opposite ends of each third spring 5 are in contact with 
the circumferentially opposite ends of the first window 29 and the first 
contact portions 20 and 24 of the plates 12 and 13. The third springs 5 
are prevented from moving radially outward and axially outward by the 
receiver portions 19 and 23. 
The fourth springs 6 are disposed in the second windows 30, respectively. 
Each fourth spring 6 is a coil spring as can be seen from FIG. 2. The 
circumferentially opposite ends of the fourth spring 6 are in contact with 
the circumferentially opposite ends of the corresponding second window 30. 
The circumferentially opposite ends of the fourth spring 46 are spaced 
from the contact portions 22 and 26 by torsion angles of (.theta..sub.3 
-.theta..sub.2), respectively, as indicated in the schematic drawing FIG. 
6. 
The intermediate member 3 is provided at its outer periphery with a 
plurality of circumferential recesses 69. Each recess 69 extends in the 
circumferential direction, and the pins 15 extend through the recesses 69, 
respectively. Each pin 15 is spaced from each of the circumferentially 
opposite ends of the corresponding recess 69 by a fourth torsion angle 
(.theta..sub.4 -.theta..sub.2). 
The intermediate member 3 is provided with third windows 31 that are 
located between adjacent first windows 29 and radially inward from the 
second windows 30. Each third window 31 has a nearly rectangular form 
extending in the circumferential direction. 
The intermediate member 3 is provided at its inner peripheral portion with 
a cylindrical portion 17 extending toward the first axial side. The 
cylindrical portion 17 is provided with a plurality of second inner teeth 
70 that extend radially inward. Each second inner tooth 70 has an R1-side 
surface 71 (its forward side in the rotating direction R1), and has an 
R2-side surface 72 (its rearward side). 
The output rotary member 4 is basically formed of a cylindrical boss 56 
extending in the axial direction. The boss 56 extends through the central 
apertures of the plates 12 and 13. The boss 56 is formed with a flange 57 
extending radially outward. The flange 57 has many features which 
correspond to, and interacts with features of the cylindrical portion 17 
of the intermediate member 3. The flange 57 is formed with a plurality of 
outer circumferential teeth 58 that extend radially outward. The outer 
circumferential teeth 58 extend circumferentially between the second inner 
circumferential teeth 70 defining a gap therebetween, the gap being a 
predetermined angle measured from corresponding circumferential sides of 
the teeth 58 and the teeth 70, as shown in FIG. 3. On a side corresponding 
to the rotational direction R1 of each of the outer circumferential teeth 
58 a surface 59 is formed. Further, on a side corresponding to the 
rotational direction R2 a surface 60 is defined on the teeth 58. An outer 
circumferential edge of the flange 57 is formed with to diametrically 
opposing recesses 62. The outer circumferential teeth 58 are formed 
between the recesses 62. Circumferential sides of the recesses 62 are 
formed with contacting portions 63. 
In the next section, a damper 8 is described. The damper 8 includes a plate 
9 and a second spring 10. The plate 9 is an annular member as shown in 
FIGS. 1 and 3, and is disposed between a first plate 12 and the 
intermediate member 3. The plate 9 is formed with an annular member 34 and 
an engagement portion 35. An inner circumferential edge of the annular 
member 34 is formed with a plurality of the first inner circumferential 
teeth 39 extending radially inward. The first inner circumferential teeth 
39 are wider in circumferential direction than the second inner 
circumferential teeth 70, and extend beyond circumferential sides of the 
second inner circumferential teeth 70. Also the first inner 
circumferential teeth 39 extend between the outer circumferential teeth 
58, and are configured to contact in circumferential direction, the outer 
circumferential teeth 58 in response to relative rotation therebetween. 
The rotational direction side R1 of the first inner circumferential teeth 
39 are formed with a surface 40, and the rotational direction side R2 is 
formed with a surface 41. 
A gap of a first torsional angle .theta..sub.1 is defined between the outer 
circumferential teeth 58 and the first inner circumferential teeth 39 on 
both circumferential sides (when there is no torque applied to the clutch 
disc assembly). The gap corresponding to the first torsional angle 
.theta..sub.2 is provided between the R1 side surface 59 of the outer 
circumferential teeth 58 and the R2 side surface 41 of the first inner 
circumferential teeth 39. The same gap having an angle .theta..sub.1 is 
defined between the R2 side surface 60 of the outer circumferential teeth 
58 and the R1 side surface 40 of the first inner circumferential teeth 39. 
A gap having the second torsional angle .theta..sub.2 is formed between the 
outer circumferential teeth 58 and the second inner circumferential teeth 
70 on both circumferential sides thereof. Specifically, the gap with the 
second torsional angle .theta..sub.2 is provided between the R1 side 
surface 59 of the outer circumferential teeth 58 and the R2 side surface 
72 of the second inner circumferential teeth 70. As well, a gap with the 
second torsional angle .theta..sub.2 is defined between the R2 side 
surface 60 of the outer circumferential teeth 58 and the R1 side surface 
71 of the second inner circumferential teeth 70 respectively. 
It should be understood that the various angles .theta..sub.1, and 
.theta..sub.2, are relative angles that change in response to the relative 
rotation of the various gear teeth. In FIG. 3, the clutch disk assembly is 
in a state where there is no torque applied. In this condition, the first 
torsional angle .theta..sub.1, on the R1 side of each tooth 39 is larger 
than the angle .theta..sub.1, the R2 side of the teeth 39, with respect to 
the surfaces of the outer circumferential teeth 58. Further, as in FIG. 3, 
the second torsional angle .theta..sub.2 is larger on the R1 side of each 
of the gear teeth 70 that on R2 side of each of the gear teeth 70, with 
respect to the outer circumferential teeth 58. Further, the combined 
angular measurement of the two second torsional angles .theta..sub.2 on 
each side of any one gear tooth 70 is larger than a corresponding 
combination of to first torsional angles .theta..sub.1. 
Also, the forth torsional angle .theta..sub.4 described above is larger 
than the third torsional angle .theta..sub.3 and the third torsional angle 
.theta..sub.3 and the forth torsional angle .theta..sub.4 each larger than 
the second torsional angle .theta..sub.2 respectively. 
Further, an inner circumferential portion of the plate 9 extends between a 
bushing 16 and the cylindrical portion 17 in axial direction. A friction 
washer 92 is disposed between the annular portion 34 of the plate 9 and a 
surface edge on an engine side of the cylindrical portion 17. The friction 
washer 92 is a member that generates friction resistance between the plate 
9 and the intermediate rotational member 3 when undergoing relatively 
rotation. The friction washer 92 has a high friction coefficient the same 
as a second friction member 76, described below, and is disposed between 
the plate 9 and the cylindrical portion 17 by a biasing member 77 
described below. 
The engagement portion 35, which is depicted in FIGS. 2, 3, 4 and 5, 
supports the second spring 10, and each engagement portion 35 includes a 
protrusion 36, contacting portions 37 and holding portion 38. A plural 
number of the protrusions 36 are formed, the protrusions 36 extend 
radially outward from the annular portion 34. The holding portions 38 
extend radially outward from a radial outer edge of the protrusions 36. 
The contacting portions 37 and the holding portions 38 are bent such that 
extend in an axial direction toward the intermediate member 3. A 
predetermined space is defined by the protrusions 36, contacting portions 
37 and holding portions 38 within the engagement portions 35. The 
predetermined space coincides with the third window 31 of the intermediate 
member 3. 
In each third window 31 and the corresponding engagement portion 35, there 
are arranged a pair of seats 46 and the pair of second springs 10. The 
second springs 10 are coil springs as shown in FIG. 4, and are disposed at 
the axially spaced positions, respectively. One of the paired second 
springs 10 is located within the engagement portion 35, and the other is, 
disposed in the third window 31. 
The seats 46 support the circumferentially opposite ends of the paired 
second springs 10, and also function as members for axially positioning 
the paired second springs 10. Each seat 46 has a rectangular main body 48 
extending in the axial direction. The main bodies 48 are in contact with 
the circumferentially opposite ends of each second spring 10. The 
circumferentially outer side of the main body 48 of each seat 46 is 
supported by the engagement portion 35 and the third window 31. The seat 
46 is provided with fitting portions 49 extending from the main body 48 
into the second springs 10, respectively. The fitting portion 49 prevents 
disengagement of the second spring 10 from the seat 46, and axially 
positions the same. Therefore, axial interference between the paired 
second springs 10 is suppressed. 
A cap 51 is engaged with the intermediate member 3 for supporting the 
paired second springs 10 and the paired seats 46 from the second axial 
side. As can be seen in FIGS. 4 and 5, the cap 51 is made of a plate 
material that is deformed to the shape depicted. The cap 51 includes a 
holding portion 52 engaged with the sides of the pair of second springs 10 
and the pair of seats 46 from the second axial side. Engagement portions 
53 extend from the holding portion 52 toward the first axial side, and 
extend on circumferentially opposite sides of the third window 31, i.e., 
between the circumferentially opposite edges of the third window 31 and 
the circumferentially outer side surfaces of the seats 46, respectively. 
Further, engagement portions 54 extend circumferentially away from each 
other and are in contact with the surface of the intermediate member 3 on 
the first axial side. The engagement portions 54 prevent the cap 51 from 
moving toward the first axial side with respect to the intermediate member 
3. As a result, the holding portion 52 of the cap 51 restricts the 
movement of the paired second springs 10 and the paired seats 46 toward 
the second axial side. 
With reference now to FIG. 1, the assembly includes a first friction member 
74 that is an annular member in contact with the surface of the flange 57 
on the second axial side. The first friction member 74 is biased toward 
the flange 57 by a first biasing member 75 disposed between the first 
friction member 74 and the inner peripheral portion of the second plate 
13. 
A second friction member 76 is an annular member that is in contact with 
the surface, on the second axial side, of the inner peripheral portion of 
the intermediate member 3. The second friction member 76 has engagement 
arms 78 that are engaged relatively non-rotatable with respect to the 
second plate 13. The first and second friction members 74 and 76 are 
engaged circumferentially non-rotatably but axially movably with respect 
to one another. Thus, the first and second friction members 74 and 76 
rotate together with the input rotary members 2, i.e., plates 12 and 13. A 
frictional resistance is generated between the first friction member 74 
and the flange 57 and is smaller than that occurring between the second 
friction member 76 and the intermediate member 3. 
The first, second, third and fourth springs 7, 10, 5 and 6 have the spring 
constants, each of which is smaller than that of the preceding one, with 
respect to the order given above. 
The damper 8 can be attached to the intermediate member 3 and the output 
rotary member 4 from the first axial side. For this attachment, the caps 
51, the paired seats 46 and the paired second springs 10 are attached in 
advance to the plate 9. Then, the caps 51 and other members supported on 
the plate 9 are fitted into the third windows 31 in the intermediate 
member 3. 
FIG. 6 is a mechanical circuit diagram of the damper mechanism of the 
clutch disk assembly 1. This figure represents relationships between the 
various members during the torsion transmission through the damper in one 
direction. As can be seen from the figure, the damper 8 permits enhanced 
dampening characteristics not found-in the prior art. Further, the clutch 
disk assemblies 1 can be manufactured with or without the damper 8 
depending on the required characteristics. 
A torque transmitting operation of the clutch disk assembly 1 will be 
described below. 
When the friction portion 11 of the input rotary member 2 is pressed 
against the flywheel (not shown), the clutch disk assembly 1 is supplied 
with a torque. The torque is transmitted successively through the first 
and second plates 12 and 13, third springs 5, intermediate member 3, 
paired second springs 10 and output rotary member 4. The torque is 
transmitted from the output rotary member 4 to the shaft (not shown) 
extending from the transmission (not shown). 
When a torque variation of the engine is transmitted to the clutch disk 
assembly 1, torsional vibration, i.e., relative rotation occurs between 
the input rotary members 2 and the output rotary member 4 so that the 
third, fourth, second and first springs 5, 6, 10 and 7 are compressed. 
The torsion operation of the clutch disk assembly 1 will now be described 
below with reference to a characteristic diagram of FIG. 7. In the 
following description, it is assumed that the input rotary members 2 are 
fixed to another stationary device (in operation they would be engaged 
with a flywheel), and the output rotary member 4 is twisted in the 
rotating direction R2 relatively to the input rotary members 2. Before the 
outer teeth 58 come into contact with the first inner teeth 39 and 
therefore the torsion angle is smaller than the first torsion angle 
.theta..sub.1, the first springs 7 are primarily compressed in the 
circumferential direction so that a characteristic of a low rigidity is 
exhibited. In this first stage, a small frictional resistance occurs 
between the first friction member 74 and the flange 57 of the output 
rotary member 4. When relative rotary displacement between the input 
rotary member 2 and the output rotary member 4 increases such that the 
torsion angle therebetween increases to the first torsion angle 
.theta..sub.1, the outer teeth 58 come into contact with the first inner 
teeth 39. Thereafter the first springs 7 and the paired second springs 10 
are compressed in parallel between the output rotary member 4 and the 
intermediate member 3 in a second stage (see FIG. 7). In the second stage, 
the torsion angle is in a range between the angle .theta..sub.1 and the 
angle .theta..sub.2. In the second stage, each pair of the second springs 
10 is compressed. Therefore, a characteristic of a relatively high 
rigidity is exhibited. While the torsion angle is between the angle 
.theta..sub.1 and the angle .theta..sub.2, the friction washer 92 slides 
between the plate. 9 and the intermediate member 3, and produces a large 
frictional resistance. Therefore, a characteristic of intermediate 
rigidity and a high hysteresis torque is exhibited in an intermediate 
region between the torsion angle .theta..sub.1 and the angle 
.theta..sub.2. When the torsion angle reaches the second torsion angle 
.theta..sub.2, the outer teeth 58 come into contact with the second inner 
teeth 70, and thereafter the first and second springs 7 and 10 are no 
longer able to undergo further compression. Thus, the relative rotation 
between the output rotary member 4 and the intermediate member 3 stops, 
and thereafter the relative rotation further occurs with respect to the 
input rotary members 2 in a third stage, as in indicated in FIG. 7. 
Therefore, the third springs 5 are compressed, and sliding occurs between 
the intermediate member 3 and the second friction member 76. As a result, 
characteristics of high rigidity and large hysteresis torque are exhibited 
in a region between the torsion angles .theta..sub.2 and the angle 
.theta..sub.3, in the third stage. The fourth springs 6 start to be 
compressed at the torsion angle .theta..sub.3, and thereafter a 
characteristic of a further increased rigidity is exhibited. When the pins 
15 come into contact with the edges of recesses 69 at the torsion angle 
.theta..sub.4, respectively, the relative rotation between the output 
rotary member 4 and the input rotary member 2 stops. 
According to the torsion characteristics described above, the 
characteristic of a low rigidity and a small hysteresis torque is 
exhibited in the first stage where the, displacement is in a range smaller 
than the first torsion angle .theta..sub.1. Therefore, gear noises during 
idling are suppressed. The characteristics of an intermediate rigidity is 
exhibited in the second stage between the angles .theta..sub.1 and angle 
.theta..sub.2, i.e., the region between the regions of the low and high 
rigidities. Therefore, the jumping phenomenon is suppressed. Particularly, 
the friction washer 92 causes a large friction, i.e., a high hysteresis 
torque in this intermediate region (second stage). This can effectively 
prevent the jumping phenomenon. 
In this embodiment, the characteristic of an intermediate rigidity is 
achieved by the damper 8, which is formed of the plate 9, paired second 
springs 10 and paired seats 46 and thus has a simple structure. 
The engagement portion 54 is engaged with a cavity 3a formed at the 
intermediate member 3 as shown in FIG. 4. However, alternatively, the 
cavity 3a may be eliminated, and the engagement portion 54 may be in 
contact with the end surface of the intermediate member 3 on the first 
axial side. 
Second Embodiment 
The clutch disk 1 shown in FIGS. 8 to 11 have the substantially same 
structure as the foregoing embodiment except for the damper 8. There are 
slight differences between the damper 8 in the first embodiment and the 
damper 8' in this second embodiment and therefore, only the damper 8' will 
be described below. 
A plate 9' (similar to the plate 9 in the first embodiment) includes an 
annular portion 84 and a plurality of engagement portions 85 similarly to 
the foregoing embodiment. An annular reinforcing plate 90 is fixed to the 
inner peripheral portion of the plate 9' by rivets 91. The reinforcing 
plate 90 is fixed to the surface on the second axial side, and is in 
contact with the surfaces of the cylindrical portion 17 of the 
intermediate member 3 and the flange 57 on the first axial side. The 
reinforcing plate 90 has teeth similar to those of the plate 9', and can 
be in contact with the outer teeth on the hub side together with the plate 
9'. Owing to increase in contact area between the teeth, wear and breakage 
are suppressed. In particular, the plate 9' has strength increased by the 
reinforcing plate 90. 
In each engagement portion 85, a projected portion 86 extends radially 
outward from the annular portion 84. Contact portions 87 extend axially 
from the circumferentially opposite ends of the projected portion 86. The 
paired contact portions 87 extend through the third window 31 in the 
intermediate member 3, and have the axial tip ends that are bent to extend 
circumferentially inward toward each other. These tip ends of the contact 
portions 87 are welded together to form an axial holding portion 89. The 
paired second elastic members and the paired seats 46 have the same 
structures as those in the first embodiment. In this second embodiment, 
the axial holding portion 89 of the plate 9' is employed instead of the 
cap in the foregoing embodiment for restricting the movement of the paired 
second springs 10 and the paired seats 46 toward the second axial side. 
Each contact portion 87 has a shorter radial width than the seat 46. Each 
edge of the third window 31 is in contact with a corresponding portion of 
each seat 46. Therefore, the third window 31 and the contact portion 87 
engage a central portion of a corresponding seat 46. 
The structure of the first inner teeth of the annular portion 84 as well as 
the relationship of the first inner teeth with respect to the other 
members are the same as those in the foregoing embodiment, and therefore 
will not be discussed below. 
This embodiment can achieve excellent effects similarly to those of the 
foregoing first embodiment. 
The invention is not restricted to the clutch disk assembly, and may be 
employed in other power transmitting devices. 
According to the damper disk assembly of the invention, an intermediate 
rigidity can be exhibited by the operation of the second elastic member 
between the operations of the first and third elastic members. Therefore, 
the jumping phenomenon that may be caused by vibration during idling can 
be suppressed. 
In the damper disk assembly according to the invention, the intermediate 
member forming the damper has a plate-like form, and respective portions 
thereof are formed by bending, thus providing a simple structure.