Damping device for torque converter

In a lock-up piston and damper device for a torque converter, a divider member is provided between the retainer plate and the lock-up piston for supporting springs of an internal circumference in series with springs of an external circumference, thereby obtaining a large torsion angle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a lock-up piston integrated damper device 
adapted for use in a torque converter with a lock-up mechanism for an 
automatic transmission for vehicles and more particularly to such a damper 
device of simple structure with a large torsion angle and with improved 
damping characteristics. 
2. Related Background Art 
In general, the torque converter realizes smooth running of the vehicle by 
power transmission through fluid, but increases the fuel consumption 
because of energy loss by fluid slippage. For avoiding such drawback, the 
recent torque converter is equipped with a lock-up mechanism. 
The lock-up mechanism is composed of a lock-up clutch having a friction 
face, wherein the fluid flow in the torque converter automatically varies 
(when the velocity of the vehicle exceeds a predetermined value), to press 
the friction face of a piston of the lock-up clutch against a front cover 
of the torque converter, thereby directly coupling the engine with the 
driven wheels. Thus the influence of the fluid slippage can be eliminated 
to improve the fuel consumption. 
Such torque converter is provided with a damper device, consisting of 
plural springs, in order to absorb the variation in the engine torque, 
resulting at the coupling and decoupling of the piston (lock-up piston) of 
the lock-up clutch with the front cover of the torque converter. 
A conventional damper device for the lock-up clutch, disclosed for example 
in the Japanese Patent Laid-Open Application No. 2-248751, is composed of 
a retaining plate and a side plate, fixed respectively on the external and 
internal circumferences in the radial direction of the piston. 
Also the Japanese Patent Laid-Open Application No. 64-75354 discloses a 
configuration in which the retaining plate and the side plate are 
integrally fixed with rivets. 
In such conventional damper devices, however, it has been difficult to 
obtain a large torsion angle, because the springs on the inner or internal 
and outer or external circumferences function in parallel manner or with a 
delay by a certain angle. 
For this reason the lock-up mechanism cannot be activated at a low vehicle 
velocity involving vibration and noises, and it has been difficult to 
improve the fuel consumption at such velocity. 
In lock-up clutches disclosed in Japanese Patent Laid-Open Application No. 
3-194247 and U.S. Pat. No. 5,246,399, the damper device is not integral 
with the lock-up piston. Therefore, an axial width of the damper device 
will be greater and the number of parts will increase. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a damper device, for use 
in the lock-up clutch, capable of providing a large torsion angle and 
exhibiting excellent damping characteristics, by causing serial function 
of plural springs on the internal circumference with those on the external 
circumference. 
The above-mentioned object can be attained, according to the present 
invention, by a damper device for use in a torque converter with a lock-up 
mechanism, including a lock-up clutch which is movable between a coupled 
state and a liberated state, and a torque converter body for power 
transmission by fluid, the damper device comprising: 
a lock-up piston of the input side; 
plural springs provided on an external circumference and an internal 
circumference of the lock-up piston; 
a retainer plate for retaining the springs on the external and internal 
circumferences; 
a divider member rotatably positioned between the lock-up piston and the 
retainer plate, for continuously retaining the springs on the external and 
internal circumferences; and 
an output member having a portion in impingement with the end faces of the 
springs on the internal or external circumference and connected to the 
output side. 
A large torsion angle can be obtained by positioning the divider member for 
serially coupling the springs of the external and internal circumferences, 
thereby causing serial function of the springs of the internal 
circumference and those of the external circumference.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Now the present invention will be explained in detail, with reference to 
the attached drawings. It is to be noted that the embodiments explained in 
the following are merely given as examples and by no means limit the 
present invention. In the attached drawings, mutually same parts are 
represented by same numbers. 
FIG. 1 is an axial cross-sectional view of a damper device 30, constituting 
a first embodiment of the present invention, in a liberated state of the 
lock-up clutch. 
The damper device 30 is provided with a retainer plate 13, which is fixed, 
at an end on the internal periphery, to an input piston (lock-up piston) 3 
by means of rivets 10 and supports springs 4 of an external circumference, 
and an output member or a clutch plate 8 which is fixed to a turbine hub 7 
by means of rivets 6. The rivets 10 fix the retainer plate 13 to the 
lock-up piston 3 in plural circumferential positions. 
The damper device 30 is further provided with a divider member 9 which is 
positioned between the lock-up piston 3 and the retainer plate 13 and is 
rendered circumferentially rotatable with respect to the lock-up piston 3 
and the rivets 10, and plural springs 4 of an external circumference and 
plural springs 5 of an internal circumference, respectively positioned in 
circumferential direction. These springs of the external and internal 
circumferences are composed of torsion springs. 
A friction member 2 is provided on the external face of the lock-up piston 
3. Thus, when the lock-up piston 3 is axially moved to come into contact 
with the internal face of a front cover 1, it is maintained in a coupled 
state with the front cover 1 across the friction member 2, whereby the 
torque is transmitted by direct coupling of the two. 
A turbine runner 14, constituting the output member of the torque converter 
unit, is fixed to the turbine hub 7 by the rivets 6. 
The retainer plate 13 is provided, at the end thereof at the external 
periphery, with spring supporting portions 13a for supporting the springs 
4 of the external circumference and end face torque transmitting portions 
13b for torque transmission by engagement with the springs 4 of the 
external circumference. Also the clutch plate 8 is provided, at an end 
thereof opposite to the side fixed to the turbine hub 7 by the rivets 6, 
with spring supporting portions 8a for supporting the springs 5 of the 
internal circumference and torque transmitting finger portions 8b for 
torque transmission by engagement with the springs 5 of the internal 
circumference. 
The divider member 9 is circumferentially movable with respect to the 
lock-up piston 3. However, as the rivets 10 fit in elongated holes 11 of 
the divider member 9 as shown in FIG. 2, the circumferential movement of 
the divider member 9 is limited by impingement of the rivet 10 on both 
ends of the elongated hole 11. Consequently, the divider member 9 is 
rendered rotatable only for a distance corresponding to the 
circumferential length of the elongated hole 11. 
The divider member 9 is provided, at the external side thereof, with torque 
transmitting finger portions 9b for torque transmission by engagement with 
the springs 4 of the external circumference, and, at the internal side 
thereof, with torque transmitting portions 9c for torque transmission by 
engagement with the springs 5 of the internal circumference. At the end at 
the internal periphery, there are provided spring supporting portions 9a 
for supporting the springs 5 of the internal circumference. 
In the first embodiment explained above, the torque is transmitted in a 
path through the lock-up (input) piston 3 directly coupled with the front 
cover 1 of the engine side through the friction member 2, the retainer 
plate 13, the springs 4 of the external circumference, the divider member 
9, the springs 5 of the internal circumference and the clutch plate 8 
constituting the output member. 
As will be apparent from the foregoing explanation, the springs of the 
external circumference and those of the internal circumference in the 
damper device are securely maintained in serial state, as the divider 
member supports these springs of the external and internal circumferences 
in continuous manner. 
In the following there will be explained a second embodiment of the present 
invention, with reference to FIG. 3. 
FIG. 3 is an axial cross-sectional view of a damper device 40, constituting 
a second embodiment of the present invention, in a liberated state of the 
lock-up clutch. 
The damper device 40 is provided with a retainer plate 16, which is fixed, 
at an end on the external periphery, to an input piston (lock-up piston) 3 
by means of rivets 10 and supports springs 5 of an internal circumference, 
and an output member 18. The rivets 10 fix the retainer plate 16 to the 
lock-up piston 3 in plural circumferential positions. 
The damper device 40 is further provided with a divider member 15 which is 
positioned between the lock-up piston 3 and the retainer plate 16 and is 
rendered circumferentially rotatable with respect to the lock-up piston 3 
and the rivets 10, and plural springs 4 of an external circumference and 
plural springs 5 of an internal circumference, respectively positioned in 
circumferential direction. These springs of the external and internal 
circumferences are composed of torsion springs. 
A friction member 2 is provided on the external face of the lock-up piston 
3. Thus, when the lock-up piston 3 is axially moved to come into contact 
with the internal face of a front cover 1, it is maintained in a coupled 
state with the front cover 1 across the friction member 2, whereby the 
torque is transmitted by direct coupling of the two. 
A turbine runner l4, constituting the output member of the torque converter 
unit, is fixed to the turbine hub 7 by the rivets 6. 
The retainer plate 16 is provided, at the end thereof on the internal 
periphery, with spring supporting portions 16a for supporting the springs 
5 of the internal circumference and torque transmitting portions 16c for 
torque transmission by engagement with the springs 5 of the internal 
circumference. 
The divider member 15 is circumferentially movable with respect to the 
lock-up piston 3. However, as the rivets 10 fit in elongated holes 21 of 
the divider member 15 as shown in FIG. 4, the circumferential movement of 
the divider member 15 is limited by impingement of the rivet 10 on both 
ends of the elongated hole 21. Consequently, the divider member 15 is 
rendered rotatable only for a distance corresponding to the 
circumferential length of the elongated hole 21. 
The divider member 15 is provided, at the external side thereof, with 
torque transmitting finger portions 15c for torque transmission by 
engagement with the springs 4 of the external circumference, and, at the 
internal side thereof, with torque transmitting portions 15b. At the end 
at the external periphery, there are provided spring supporting portions 
15a for supporting the springs 4 of the external circumferences. 
The output member 18 is fixed, by fixing portions 18b, to the external face 
of the turbine runner 14, and is provided with torque transmitting finger 
portions 18a, for torque transmission by engagement with the springs 4 of 
the external circumference. 
As will be apparent from the foregoing explanation, the springs of the 
external circumference and those of the internal circumference in the 
damper device are securely maintained in serial state, as the divider 
member supports these springs of the external and internal circumferences 
in continuous manner. 
In the second embodiment explained above, the torque is transmitted in a 
path through the lock-up (input) piston 3 directly coupled with the front 
cover 1 of the engine side through the friction member 2, the retainer 
plate 16, the springs 5 of the internal circumference, the divider member 
15, the springs 4 of the external circumference and the output member 8 at 
the output side. 
As explained in the foregoing, the first and second embodiments of the 
present invention provide a maximum damping characteristic, as the springs 
5 of the internal circumference and those 4 of the external circumference 
function serially through the divider member 9 or 15. 
Consequently the present invention provides the following advantages. 
The function of the springs of the internal circumference and those of the 
external circumference in serial manner allows to provide a large torsion 
angle, thereby ensuring damping characteristics of a wide angular range. 
It is therefore possible to improve the vibration attenuating effect, and 
to expand the lock-up range, thereby contributing to the reduction in the 
fuel consumption of the vehicle. 
Also the damper device of the present invention is compact because the 
divider member is positioned between the lock-up piston and the retainer 
plate, and is advantageous in cost since the number of component parts is 
maintained at a minimum. 
In the above-mentioned first and second embodiments, the lock-up piston is 
integrally provided with the damper device so that the number of the parts 
is decreased.