Torque absorbing device

A torque absorbing device includes a hub member having a flange portion, plate members disposed around a hub portion of the hub member so as to be positioned opposite the flange portion in the axial direction, a plurality of torsion members elastically interconnecting the hub member and the plate members in the circumferential direction of the disc, and a plurality of seat members each of which is disposed among each of the torsion members, the plate members and the hub member. Each seat member has one side face portion contacting the circumferential end surface of each of the torsion members and the other side face portion contacting the plate members and the flange portion of the hub member. The other face portion is provided with a projected holding portion held on the flange portion of the hub member so as not to be able to move relative to the hub member and a guide portion nipping the flange portion of the hub member in the axial direction of the disc.

FIELD OF THE INVENTION 
The present invention relates to a torque absorbing device, and more 
particularly to a torque variation absorbing device which transmits input 
torque from a plate to a hub member through a plurality of torsion members 
which absorb the input torque. 
BACKGROUND OF THE INVENTION 
A conventional torque absorbing device is disclosed in, for example, 
Japanese Patent Application Laid-Open Publication Nos. 58 (1983)-187623, 
and 59 (1984)-26625, and Japanese Utility-Model Application Laid-Open 
Publication No. 59 (1984)-166030. This torque absorbing device includes a 
hub member having a flange portion and plate members which are disposed 
around a hub portion of the hub member so as to be opposite to the flange 
portion. Each of the plate members and the flange portion of the hub 
member have a plurality of window portions each of which extends in the 
circumferential direction of the disc. The plate members are disposed so 
that their window portions overlap the window portions of the flange 
portion of the hub member. The hub member and the plate members are 
elastically connected to each other in the circumferential direction of 
the disc through a plurality of torsion members which are each disposed in 
the overlapped window portions so that an input torque is transmitted from 
the plate members to the hub member through the torsion members while 
being absorbed by a flexible contraction of each torsion member. In this 
conventional torque absorbing device, a seat member is disposed among an 
axial end surface of each of the torsion members, circumferential end 
surfaces of the window portions of the plate members, and the flange 
portion of the hub member. A supporting portion having a flange shape is 
formed on an edge portion of each window portion of the plate members and 
the seat members are prevented from relative movement with regard to the 
plate members by the supporting portions and the circumferential surfaces 
and the circumferential end surfaces of the window portions. 
In the above known torque absorbing device, however, the seat members are 
not prevented from relative movement with respect to the hub member. 
Therefore, in the case where, for example, the torsion members are 
contracted by the torque through the plate members, the seat members 
located in the input side keep contacting the circumferential end surfaces 
of the window portions of the plate members in order to prevent movement. 
On the other hand, the seat members located in the output side are 
separated from the circumferential end surfaces of the window portions of 
the plate members. As a result, the seat members located in the output 
side can be moved with the torsion members in the diametrical and axial 
direction of the device by centrifugal force and the like. Accordingly, 
the seat members located in this movable side are pressed to the plate 
members and this movement of the seat members may cause wear. 
A need exists, therefore, for a torque absorbing device which overcomes the 
above drawback. 
It would be desirable to provide a torque absorbing device in which the 
wear of the seat member caused by the plate members is prevented. 
SUMMARY OF INVENTION 
To address at least these needs, the present invention provides according 
to one aspect a torque absorbing device which includes a hub member having 
a flange portion, plate members disposed around a hub portion of the hub 
member so as to be opposite to the flange portion in the axial direction, 
a plurality of torsion members elastically connected between the hub 
member and the plate members in the circumferential direction of the disc 
and a plurality of seat members each of which is disposed among each of 
the torsion members, the plate members and the hub member. Each of the 
seat members has one side face portion in contact with the circumferential 
end surface of each of the torsion members and the other side face portion 
in contact with the plate members and the flange portion of the hub 
member. The other face portion is provided with a projected holding 
portion held on the flange portion of the hub member so as not to be able 
to move relative to the hub member and a guide portion nipping the flange 
portion of the hub member in the axial direction of the disc. 
According to another aspect of the invention, a torque absorbing device 
includes a hub member having a radially extending flange portion and a hub 
portion, plate members disposed around the hub portion on opposite sides 
of the flange portion, a plurality of torsion members elastically 
interconnecting the hub member and the plate members in the 
circumferential direction to absorb torque created during relative 
rotational movement between the hub member and the plate members, and a 
seat member positioned at each end of each respective torsion member. Each 
seat member has a first side face contacting the end of the respective 
torsion member and an oppositely facing second side face, with the second 
side face of each seat member having a projecting holding portion which is 
received in recesses provided in the flange portion and the plate members 
to hold the seat member on the hub member and the plate members in 
circumferential and diametrical directions. 
In accordance with another aspect of the invention, a torque absorbing 
device includes a hub member having a radially extending flange portion 
and a hub portion, plate members disposed around the hub portion on 
opposite sides of the flange portion, a plurality of torsion members 
elastically interconnecting the hub member and the plate members in a 
circumferential direction to absorb torque created during relative 
rotational movement between the plate members and the hub member, and a 
seat member positioned at each end of each respective torsion member. Each 
seat member possesses a first side face contacting the end of the 
respective torsion member and an oppositely facing second side face. The 
second side face of each seat member has a pair of projecting guide 
portions between which is pinched the flange portion of the hub member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1 and FIG. 2, a torque absorbing device A of the present 
invention is applied to a clutch disc of a frictional clutch which is 
disposed between the engine (not shown) and the transmission (not shown) 
of an automobile. A plurality of plate springs 8 having waves are fixed to 
an outer circumferential portion of a disc plate 2 at regular intervals in 
the circumferential direction by rivets 9. A pair of circular facings 
(frictional members) 6A, 6B which are held between a flywheel (not shown) 
of the engine and a pressure plate (not shown) by a spring force are fixed 
as an input member to side faces of the plate springs 8 by rivets 7 to 
thereby sandwich the plate springs 8 therebetween. An input shaft (not 
shown) of the transmission is inserted as an output member into a hole of 
a hub portion 11 of a hub member 1. The rotation of the hub member 1 is 
transmitted to the input shaft through a spline engagement. 
As shown in FIG. 1 and FIG. 2, the torque absorbing device A includes the 
hub member 1 having the hub portion 11 and a flange portion 12, the disc 
plate 2, a sub plate 3 and three torsion members 5. The flange portion 12 
extends radially outwardly from the outer circumferential portion of the 
hub portion 11. The disc plate 2 and the sub plate 3 are disposed around 
the hub portion 11 of the hub member 1 so as to be positioned on opposite 
sides of the flange portion 12 in the axial direction, and thereby 
sandwich the flange portion 12 of the hub member 1 therebetween. The three 
torsion members 5 elastically interconnect the hub member 1 and the plates 
2, 3 in the circumferential direction of the device. 
In this embodiment, each of the torsion members 5 is comprised of a first 
coil spring 51 having a relatively larger diameter and a second coil 
spring 52 whose diameter is smaller than that of the first coil spring 51. 
The smaller coil spring 52 is disposed in the first coil spring 51 so as 
to be parallel with the first coil spring 51. Of course, each of the 
torsion members 5 need not necessarily be comprised of two coil springs 
and it is possible to employ a torsion member consisting of a single coil 
spring. Furthermore, it is possible to use an elastic member such as 
rubber and the like as a torsion member. 
Three windows 21, 31 are formed on the disc plate 2 and the sub plate 3 at 
regular intervals. These windows 21, 31 extend in the circumferential 
direction and are disposed on a concentric circle. Three notches 13 which 
extend in the circumferential direction and which are located on the same 
concentric circle are formed on the flange portion 12 of the hub member 1 
at the same regular intervals. The notches 13 and the windows 21, 31 
overlap one another in the circumferential direction with every two 
overlapping windows 21, 31 and every one overlapping notch 13 forming a 
group. Each of the torsion members 5 is disposed in one of the three 
groups of notches and windows under a condition in which the torsion 
member 5 is contracted by a predetermined amount. Seat members 53, 54 are 
disposed adjacent the axial end portions of the torsion members 5, the 
circumferential end portions of the notches 13 and the circumferential end 
portions of the windows 21, 31 so as to be pressed on the circumferential 
end portions of the notches 13 and the windows 21, 31 by the spring force 
of the torsion members 5. 
As shown in FIG. 2, FIG. 3 and FIG. 4, the outer circumferential portions 
of the windows 21, 31 have a general arc shape (see FIG. 3) and are 
provided with first edge portions 21a, 31a, respectively (see FIGS. 2 and 
4). The first edge portions 21a, 31a are formed by bending and have a 
flange shape that projects in the axial direction and extends in the 
circumferential direction to at least partially surround the radial outer 
portions of the torsion members 5 on opposite sides. 
The inner circumferential portions of the window portions 21, 31 have a 
generally straight shape (see FIG. 3) and are provided with third edge 
portions 21c, 31c, respectively (see FIGS. 2 and 4). The third edge 
portions 21c, 31c are formed by bending and have a flange shape that 
projects in the axial direction and extends in the circumferential 
direction to surround the radial inner portions of the torsion members 5. 
the seat members 53, 54 and the torsion members 5 are prevented from 
jumping out of the window portions 21, 31 by these first and third edge 
portions 21a, 31a, 21c, 31c under the condition that the torsion members 5 
are contracted. 
As seen with reference to FIGS. 3 and FIG. 4, second edge portions 21b, 31b 
are formed on the portions of the disc plate 2 and the sub plate 3 
respectively which are adjacent to the circumferential end portions of the 
outer circumferential portions of the window portions 21, 31. The second 
edge portions 21b, 31b are formed by drawing to project in the axial 
direction of the disc and to form a space between the flange portion 12 of 
the hub member 1 and the plates 2, 3. These spaces open into the window 
portions 21, 31. The second edge portions 21b, 31b are successive to the 
first edge portions 21a, 31a, whereby the strength of the first edge 
portions 21a, 31a against the load applied to the first edge portions 21a, 
31a due to the contraction of the torsion members 5 and the centrifugal 
force applied to the torsion members 5 is improved. 
As shown in FIG. 3 to FIG. 9, one side face (i.e., a first side face) 53a, 
54a of the seat members 53, 54 which contacts the axial end portions of 
the torsion members 5 have outer flat surfaces as well as inner flat 
surfaces that project from the outer flat surfaces. The outer flat 
surfaces contact the axial end portions of the first coil springs 51 and 
the inner fiat surfaces contact the axial end portions of the second coil 
springs 52. 
The opposite side face (i.e., a second side face) 53b, 54b of the seat 
members 53, 54 contacts the circumferential end portions of the notches 13 
of the flange portion 12 of the hub member 1 at the center portion in the 
axial direction of the disc. The side faces 53b, 54b of the seat members 
53, 54 also contact the circumferential end portions of the windows 21, 31 
of the plates 2, 3 at both outer portions in the axial direction of the 
disc. 
On the radial inner portions of the second faces 53b, 54b, holding portions 
53c, 54c are formed as seen in FIGS. 6, 7 and 9. These holding portions 
53c, 54c have a semi-circular cross-sectional shape, project toward the 
circumferential end portions of the notches 13 and the windows 21, 31, and 
project in the axial direction of the disc. On the other hand, a pair of 
guide portions 53d, 54d which project toward the circumferential end 
portions of the notches 13 and the windows 21, 31 are formed on each of 
the radial outer portions of the second side faces 53b, 54b as seen in 
FIGS. 6-8. Each pair of guide portions 53d, 54d extends in parallel with 
the side face of the flange portion 12 in the diametrical direction. 
On the radial inner portions of the circumferential end portions of the 
notches 13 of the flange portion 12 of the hub member 1 and the windows 
21, 31 of the plates 2, 3, concave portions 13a, 21d, 31d are formed which 
have the same cross-sectional shape (i.e., half circle or semi-circle) as 
the holding portions 53c, 54c so as to be opposite to the holding portions 
53c, 54c. The holding portions 53c, 54c are positioned in the concave 
portions 13a, 21d, 31d so that the seat members 53, 54 are held on the hub 
member 1, the disc plate 2, and the sub plate 3 in the circumferential and 
diametrical directions of the disc. In this embodiment, the 
cross-sectional shape of the holding portion 53c (54c) is a half circle or 
semi-circle, but it is possible to utilize a holding portion having other 
cross-sectional shapes so long as the concave portion 13a (21d, 31d) has 
the same cross-sectional shape as the holding portion to thereby hold the 
seat member 53 (54). Furthermore, the flange portion 12 of the hub member 
1 is nipped held between each pair of guide portions 53d, 54d in the axial 
direction of the disc and each pair of guide portions 53d, 54d is disposed 
in the spaces formed by the second edge portions 21b, 31b. Thus, the seat 
members 53, 54 are supported by the hub member 1, the disc plate 2 and the 
sub plate 3 in the axial direction of the disc. 
The above-described embodiment of the torque absorbing device operates as 
follows. When the clutch is connected, torque is transmitted to the disc 
plate 2 and the sub plate 3 through the facings 6A, 6B. The torque which 
is transmitted to the plates 2, 3 is further transmitted to the 
transmission through the torsion members 5 and the hub member 1. At this 
time, the hub member 1 and the plates 2, 3 are rotated relative to one 
another with a predetermined torsion characteristic while the torsion 
members 5 are contracted in response to the value of the applied torque. 
Thus, an absorbing affect with respect to the torque transmission is 
obtained. The torque absorbing device A is provided with a hysteresis 
mechanism comprising a first thrust plate 10a, a second thrust plate 10b 
and a dish spring 10c. The first thrust plate 10a is disposed around the 
hub portion 11 of the hub member 1 between the disc plate 2 and the flange 
portion 12 of the hub member 1. The second thrust plate 10b is disposed 
around the hub portion 11 of the hub member 1 between the sub plate 3 and 
the flange portion 12 of the hub member 1. Hence, the hysteresis 
characteristics are added to the torsion characteristics when the hub 
member 1 and the plates 2, 3 are rotated relative to one another. As a 
result, a damping affect with respect to torque transmission from the 
plates 2, 3 to the hub member 1 is obtained. By way of example, when each 
of the torsion members 5 is contracted by torque which is applied from 
left side in the circumferential direction in FIG. 3, the second side face 
53b of each of the seat members 53 contacts the respective circumferential 
end portions of the plates 2, 3 which are located at the input side (left 
side in FIG. 3) and is separated from the respective circumferential end 
portions of the notches 13 of the flange portion 12 of the hub member 1 
which is located at the input side (left side in FIG. 3). The second side 
face 54b of each of the seat members 54 contacts the circumferential end 
portions of the notch portions 13 of the flange portion 12 of the hub 
member 1 which is located at the output side (right side in FIG. 3) and is 
separated from each of the circumferential end portions of the plates 2, 3 
located at the output side (right side in FIG. 3). At this time, each of 
the seat members 53 is prevented from moving relative to the plates 2, 3 
in the circumferential, diametrical and axial directions of the device by 
the engagement between each of the holding portions 53c and each of the 
concave portions 21d, 31d, the engagement between each of the guide 
portions 53d and each of the second edge portions 21b, 31b, and each of 
the first edge portions 21a, 31a. Furthermore, each of the seat members 54 
is prevented from moving relative to the hub member 1 in the 
circumferential, diametrical and axial directions of the device by the 
engagement between each of the holding portions 54c and each of the 
concave portions 13a and the fact that the flange portion 12 of the hub 
member 1 is nipped by each of the guide portions 54d. 
The flange portion 12 of the hub member 1 is provided with three holes 12a 
which are formed between the adjacent notches 13. Thus, the stress which 
is applied from each of the holding portions 53c to the flange portion 12 
is efficiently dispersed. As a result, the strength of the flange portion 
12 of the hub member 1 is maintained and therefore it is possible to 
reduce the thickness of the flange portion 12. 
As mentioned above, when the torsion members 5 are contracted, the seat 
members (in the above description, the seat members 54) which are movable 
relative to the disc plate 2 and the sub plate 3 are prevented from moving 
by the hub member 1. Hence, these seat members are not pressed on the disc 
plate 2 and the sub plate 3 and therefore are prevented from wearing. 
Furthermore, since the seat members 53, 54 are prevented from moving 
relative to the hub member 1 by the holding portions 53c, 54c and the 
guide portions 53d, 54d, it is possible to dispose the torsion members 5, 
including the seat members 53, 54, in the notch portions 13, each of whose 
outer circumferential portions is opened. As a result, it is not necessary 
to form window portions on the flange portion 12 of the hub member 1 and 
so the weight of the hub member 1 is decreased. 
FIG. 10 shows a partly expanded sectional view of a second embodiment of 
the present invention. In FIG. 10, the same parts as compared with FIG. 3 
are identified by the same reference numerals as those utilized in FIG. 3. 
In this second embodiment, the windows 21', 31' and the notches 13' have a 
fan shape. Both circumferential end surfaces of each of the windows 21', 
31' and the notches 13' have an inclination of a predetermined angle C 
with respect to the flat surfaces of the second side faces 53b, 54b of the 
seat members 53, 54 so as to form a space therebetween. Thus, the seat 
members 53, 54 are rotatable around the holding portions 53c, 54c in the 
circumferential direction with regard to the flange portions 12 of the hub 
member 1, the disc plate 2 and the sub plate 3. In the situation where the 
seat members 53, 54 are rotated, the seat members 53, 54 are supported by 
the holding portions 53c, 54c and the concave portions 13a, 21d, 31d in 
the diametrical direction of the disc and are supported by the guide 
portions 53d, 54d in the axial direction of the disc. 
As shown in FIG. 10, the first coil spring 51 is provided with first wound 
portions 51a and a second wound portion 51b. The first wound portions 51a 
extend a certain distance toward the center portion from both axial end 
portions on which a seat portion 51c is formed. Both first wound portions 
51a have the same number of windings and the same pitch. The second wound 
portion 51b is located between both first wound portions 51a and has a 
pitch smaller than that of the first wound portions 51a. In this 
embodiment, the second coil spring 52 has an equal or constant pitch 
throughout, but it is possible to change the pitch of the second coil 
spring 52 in the same manner as the first coil spring 51. As mentioned 
above, since the first coil spring 51 having different pitches is 
symmetrical in the axial direction, even if the first coil spring 51 is 
installed on the hub member 1, the disc plate 2 and the sub plate 3 in 
either axial direction, the unbalance of the weight does not occur. Thus, 
it is possible to easily install the torsion member 5 on the hub member 1, 
the disc plate 2 and the sub plate 3 so that excessive man-hour time in 
assembling is prevented. Also, erroneous assembling is avoided. In this 
embodiment, the other structures are the same as the above mentioned first 
embodiment. 
When the clutch is connected, torque is transmitted from the disc plate 2 
and the sub plate 3 to the hub member 1, through the torsion members 5. At 
this time, the hub member 1 and the plates 2, 3 are rotated relative to 
one another with the torsion characteristics shown in FIG. 11 while the 
torsion members 5 are contracted in response to the degree or amount of 
applied torque. As shown in FIG. 11, the torsion members 5 are contracted 
in response to the torque. In the area D of the torsional angle shown in 
FIG. 11, the torsion members 5 are contracted more or less and thereby the 
seat members 53, 54 are rotated with the predetermined angle C to contact 
circumferential end surfaces of each of the windows 21 ', 31', and the 
notches 13' have an inclination of a predetermined angle C with respect to 
the flat surfaces of the second side faces 53b, 54b of the seat members 
53, 54. As a result, the torsion characteristic K1 is obtained and the 
torque transmission of the torque value based on the torsion 
characteristic K1 is realized. In the area E of the torsion angle shown in 
FIG. 11, the first wound portion 51a and the second wound portion 51b of 
each of the first coil springs 51 and each of the second coil springs 52 
are contracted. Consequently, the torsion characteristic K2 is obtained 
and the torque transmission of the torque value based on the torsion 
characteristic K2 is realized. Furthermore, in the area F of the torsion 
angle shown in FIG. 11, the first wound portion 51a of each of the first 
coil springs 51 is completely contracted and the second wound portion 51b 
of each of the first coil springs 51 and each of the second coil springs 
52 are contracted. Thereby, the torsion characteristic K3 is obtained and 
the torque transmission of the torque value based on the torsion 
characteristic K3 is realized. 
As mentioned above, in this second embodiment, when the torsion members 5 
are contracted, the seat members 53, 54 are rotated relative to the disc 
plate 2, the sub plate 3 and the flange portion 12 of the hub member 1 in 
the circumferential direction of the disc. Thus, the torsion 
characteristic K1 due to the rotation of the seat members 53, 54 is 
obtained before the torsion characteristics K2, K3 due to the contraction 
of the torsion members 5. Accordingly, multistage torsion characteristics 
are obtained without various torsion members 5 and so it is possible to 
reduce the number of parts and simplify the structures. 
As also mentioned above, according to the present invention, the seat 
members which are movable relative to the plate members are prevented from 
moving relative to the hub member in the diametrical and the axial 
directions of the disc by the engagement between the holding portions and 
the flange portion of the hub member and the engagement between the guide 
portions and the flange portion of the hub member. Therefore, when the 
torsion members are contracted, the seat members are not pressed on the 
plate members and so it is possible to prevent the seat members from 
wearing. Furthermore, since it is possible to form a space for receiving a 
torsion member on the flange portion of the hub member by a notch portion, 
it is possible to decrease the weight of the hub member. 
The principles, preferred embodiments and modes of operation of the present 
invention have been described in the foregoing description. The invention 
which is intended to be protected herein should not, however, be construed 
as limited to the particular forms disclosed, as these are to be regarded 
as illustrative rather than restrictive. Variations and changes may be 
made, and equivalents employed, by those skilled in the art without 
departing from the spirit of the present invention. Accordingly, it is 
expressly intended that all such variations, changes and equivalents which 
fall within the spirit and scope of the present invention as defined in 
the claims be embraced thereby.