Lockup device for torque converter

1. A lock-up device for a torque converter, the lock-up device disposed between a front cover coupled to an engine-side member and a torque converter body, the lock-up device configured to directly transmit a torque from the front cover to a turbine of the torque converter body, the lock-up device comprising:

a clutch portion configured to transmit the torque from the front cover to an output side;

an output rotary member coupled to the turbine, the output rotary member rotatable relatively to the clutch portion;

a plurality of first elastic members for elastically and rotation-directionally coupling the clutch portion and the output rotary member; and

a dynamic damper device coupled to a member of a power transmission path from the clutch portion to the output rotary member, the dynamic damper device configured to attenuate variation in rotational speed, wherein

the dynamic damper device includes

a damper plate having a plurality of circumferentially extending first openings, the damper plate configured to be rotated together with the output rotary member,

a pair of inertia members disposed on both axial sides of the damper plate, the pair of inertia members rotatable relatively to the damper plate, each of the inertia members having circumferentially extending second openings located to oppose the first openings, and

a plurality of second elastic members accommodated in the first openings and the second openings, the second elastic members elastically coupling the damper plate and the pair of inertia members.

2. The lock-up device recited in claim 1 , wherein

each of the inertia members has an annular shape, and

the damper plate has a spigot part, the spigot part contacted to one of inner peripheral surfaces of the inertia members to radially position the inertia members.

3. The lock-up device recited in claim 1 , further comprising:

an intermediate member for causing at least two of the plural first elastic members to act in a series-like manner, the intermediate member rotatable relatively to the clutch portion and the output rotary member, wherein

the damper plate is coupled to the intermediate member.

4. The lock-up device recited in claim 1 , further comprising:

a pair of lid members, each of the pair of lid members disposed axially outside each of the pair of inertia members to close the second openings.

5. The lock-up device recited in claim 4 , wherein

the damper plate has a plurality of circumferentially extending elongated holes located circumferentially between or among the plural first openings, and

the lock-up device further comprises a plurality of coupling members, the coupling members axially passing through the elongated holes, the coupling members coupling the pair of inertia members and the pair of lid members.

6. The lock-up device recited in claim 5 , wherein the

first openings and the elongated holes of the damper plate are disposed on a common circle.

7. The lock-up device recited in claim 1 , wherein the dynamic damper device includes a hysteresis torque generating mechanism, the hysteresis torque generating mechanism configured to generate a first hysteresis torque in a low rotational speed range and generate a second hysteresis torque larger than the first hysteresis torque in middle to high rotational speed ranges.

8. The lock-up device recited in claim 7 , wherein the hysteresis torque generating mechanism includes

a slider configured to be rotated together with the inertia members, the slider radially movable with respect to the inertia members, the slider having a rotation-directionally extending slide surface, and

a contact member configured to be rotated together with the damper plate, the contact member configured to be contacted to the slide surface of the slider in the low rotational speed range to restrict a relative torsion angular range thereof with respect to the inertia members to a first angular range, the contact member configured to be contacted to the slide surface of the slider in the middle rotational speed range including a first rotational speed higher than a second rotational speed in the low rotational speed range to restrict the relative torsion angular range thereof with respect to the inertia members to a second angular range narrower than the first angular range, the contact member configured to be contacted to the slide surface of the slider in the high rotational speed range including a third rotational speed higher than the first rotational speed in the middle rotational speed range to prevent relative torsional rotation thereof with respect to the inertia members.

9. The lock-up device recited in claim 8 , wherein the slider has a lock part on a rotation-directional middle of the slide surface thereof to enable the contact member to be fitted thereto.