Fluid transmission device

1. A fluid transmission device capable of transmitting power between a first rotating element and a second rotating element by kinetic energy of a fluid and capable of transmitting power between the first rotating element and the second rotating element via a lock-up clutch, the fluid transmission device comprising:

a first damping mechanism including a rotating body disposed in a path for transmitting power between the first rotating element and the second rotating element via the lock-up clutch for restraining variations in rotation of the second rotating element, and

a coupling mechanism configured to release the first damping mechanism from the first rotating element and the second rotating element when the lock-up clutch is released and couple the first damping mechanism to the first rotating element and the second rotating element when the lock-up clutch is engaged, wherein

the lock-up clutch comprises a movable element mounted on the second rotating element and movable in a direction of an axial line toward the coupling mechanism to couple the first damping mechanism between the first rotating element and the second rotating element through the movable element when the lock-up clutch is engaged, the axial line being a center of rotation of the second rotating element, and

the first damping mechanism further includes a support supporting the rotating body freely rotatable independently of at least the second rotating element when the lock-up clutch is disengaged.

2. The fluid transmission device according to claim 1 , wherein the lock-up clutch further comprises:

a first friction member disposed on the first rotating element; and

a second friction member disposed on the movable element,

wherein engagement of the lock-up clutch is a state in which power transmission between the first friction member and the second friction member is enabled,

wherein release of the lock-up clutch is a state in which power transmission between the first friction member and the second friction member is blocked,

wherein the first damping mechanism is apart from the first friction member and the second friction member when the lock-up clutch is released, and

wherein the first damping mechanism is coupled to the first friction member and the second friction member when the lock-up clutch is engaged.

3. The fluid transmission device according to claim 2 , further comprising a second damping mechanism configured to couple the movable element and the second rotating element, and restrain the variations in rotation of the second rotating element,

wherein the movable element is rotatable with respect to the second rotating element about the axial line.

4. The fluid transmission device according to claim 3 , wherein the first damping mechanism comprises:

a ring, which is the rotating body, mounted on the first rotating element through the support, the ring being rotatable about the axial line; and

a mass body mounted on the ring and pivotable in the direction of rotation of the ring,

wherein the ring moves away from the first friction member and the second friction member when the lock-up clutch is released, and

wherein the ring is coupled to the first friction member and the second friction member when the lock-up clutch is engaged.

5. The fluid transmission device according to claim 4 , wherein the mass body is disposed outside the ring in a radial direction about the axial line.

6. The fluid transmission device according to claim 4 , wherein the mass body is disposed inside the ring in the radial direction about the axial line.

7. The fluid transmission device according to claim 2 , wherein the first damping mechanism comprises:

a ring, which is the rotating body, mounted on the first rotating element through the support, the ring being rotatable about the axial line; and

a mass body mounted on the ring and pivotable in the direction of rotation of the ring,

wherein the ring moves away from the first friction member and the second friction member when the lock-up clutch is released, and

wherein the ring is coupled to the first friction member and the second friction member when the lock-up clutch is engaged.

8. The fluid transmission device according to claim 7 , wherein the mass body is disposed outside the ring in a radial direction about the axial line.

9. The fluid transmission device according to claim 7 , wherein the mass body is disposed inside the ring in the radial direction about the axial line.

10. A fluid transmission device capable of transmitting power between a first rotating element and a second rotating element by kinetic energy of a fluid and capable of transmitting power between the first rotating element and the second rotating element via a lock-up clutch, the fluid transmission device comprising:

a first damping mechanism disposed in a path for transmitting power between the first rotating element and the second rotating element via the lock-up clutch for restraining variations in rotation of the second rotating element, and

a coupling mechanism configured to release the first damping mechanism from the first rotating element and the second rotating element when the lock-up clutch is released and couple the first damping mechanism to the first rotating element and the second rotating element when the lock-up clutch is engaged, wherein

the lock-up clutch comprises:

a movable element mounted on the second rotating element and movable in a direction of an axial line, which is a center of rotation of the second rotating element;

a first friction member disposed on the first rotating element; and

a second friction member disposed on the movable element,

engagement of the lock-up clutch is a state in which power transmission between the first friction member and the second friction member is enabled,

release of the lock-up clutch is a state in which power transmission between the first friction member and the second friction member is blocked,

the first damping mechanism is apart from the first friction member and the second friction member when the lock-up clutch is released,

the first damping mechanism is coupled to the first friction member and the second friction member when the lock-up clutch is engaged,

the first damping mechanism comprises:

a ring mounted on the first rotating element so as to be rotatable about the axial line; and

a mass body mounted on the ring and pivotable in the direction of rotation of the ring,

the ring moves away from the first friction member and the second friction member when the lock-up clutch is released, and

the ring is coupled to the first friction member and the second friction member when the lock-up clutch is engaged.

11. The fluid transmission device according to claim 10 , further comprising a second damping mechanism configured to couple the movable element and the second rotating element, and restrain the variations in rotation of the second rotating element,

wherein the movable element is rotatable with respect to the second rotating element about the axial line.

12. The fluid transmission device according to claim 10 , wherein the mass body is disposed outside the ring in a radial direction about the axial line.

13. The fluid transmission device according to claim 10 , wherein the mass body is disposed inside the ring in the radial direction about the axial line.

14. A fluid transmission device capable of transmitting power between a first rotating element and a second rotating element by kinetic energy of a fluid, the first rotating element being coupled to an input rotating shaft and the second rotating element being coupled to an output rotating shaft, the fluid transmission device comprising:

a lock-up clutch coupled to the second rotating element and the output rotating shaft, the lock-up clutch being configured to couple the first rotating element and the second rotating element to transmitting power from the input rotating shaft to the output rotating shaft through the lock-up clutch;

a damper including

a damping mechanism disposed in a path for transmitting power between the first rotating element and the second rotating element through the lock-up clutch for restraining variations in rotation of the second rotating element, and

a support for the damping mechanism, the support being configured to be freely rotatable independently of at least the output rotating shaft around a rotation axis of the input and output rotating shafts;

a coupling mechanism configured to release the damping mechanism from the first rotating element and the second rotating element when the lock-up clutch is released and couple the damping mechanism to the first rotating element and the second rotating element when the lock-up clutch is engaged.