Damper

1. A damper comprising:

a first rotating element that is rotatable around a rotation center;

a second rotating element that is rotatable around the rotation center;

an elastic element that elastically expands and contracts in response to relative rotation of the first rotating element and the second rotating element; and

a limiter provided in the first rotating element, wherein

the limiter includes

a lining plate having a first sliding surface which faces a first direction along an axial direction of the rotation center and is surface-hardened,

a first cover plate having a second sliding surface which is in contact with the first sliding surface and a first abutting surface which is positioned radially outside the rotation center from the second sliding surface and faces a second direction opposite to the first direction,

a second cover plate having an outer edge part which has a second abutting surface that abuts against the first abutting surface and is coupled to the first cover plate, and an inner edge part which projects radially inward from the outer edge part and is positioned away from the lining plate on a side opposite to the first cover plate, and

a biasing member which is provided between the inner edge part and the lining plate and presses the first sliding surface against the second sliding surface,

in a case where a value of a difference in torque between the lining plate and the first cover plate is equal to or greater than a predetermined value, the first sliding surface slides with

the second sliding surface so that the lining plate and the first cover plate relatively rotate around the rotation center, and

the second sliding surface is, in a free state of the first cover plate, inclined with respect to the first abutting surface towards the second direction on a radially inward side of the second sliding surface.

2. The damper according to claim 1 , wherein

the lining plate has a third sliding surface which faces the second direction and is surface-hardened, and

the limiter has a pressure plate which has a fourth sliding surface that is in contact with the third sliding surface, is provided between the lining plate and the biasing member, and rotates integrally with the first cover plate around the rotation center in a case where the value of the difference in torque between the lining plate and the first cover plate is equal to or greater than the predetermined value so that the fourth sliding surface slides with the third sliding surface.

3. The damper according to claim 1 , wherein the lining plate has an annular portion having the first sliding surface, and a projecting portion that projects radially inward from the annular portion,

the second rotating element has a first arm that projects radially outward and a second arm different from the first arm that projects radially outward,

the projecting portion has a first stopper that faces one direction in a circumferential direction of the rotation center and limits rotation of the second rotating element to the other direction in the circumferential direction with respect to the first rotating element by abutting against the first arm, and a second stopper that faces the other direction in the circumferential direction and limits rotation of the second rotating element to the one direction in the circumferential direction with respect to the first rotating element by abutting against the second arm, and

the lining plate is provided with a cutout portion which is recessed radially outward between the first stopper and the second stopper, and is opened radially inward.

4. The damper according to claim 3 , wherein

a hardness of the projecting portion is lower than a hardness of the annular portion.

5. The damper according to claim 1 , wherein

a radially inner edge of the second sliding surface is a curved edge or a chamfered edge.

6. The damper according to claim 1 , wherein

a radially outer edge of the first sliding surface is a curved edge or a chamfered edge.

7. The damper according to claim 1 , wherein

a thickness of the lining plate in the axial direction is thinner than a thickness of the first cover plate in the axial direction.

8. The damper according to claim 1 , wherein

in a free state of the first rotating element, an angle of the second sliding surface inclined with respect to the first abutting surface is 1° to 10°.

9. The damper according to claim 1 , wherein

the lining plate has a third sliding surface which faces the second direction and is surface-hardened,

the lining plate has an annular portion having the third sliding surface, and a projecting portion that projects radially inward from the annular portion,

the second rotating element has a first arm that projects radially outward and a second arm different from the first arm that projects radially outward,

the projecting portion has a first stopper that faces one direction in a circumferential direction of the rotation center and limits rotation of the second rotating element to the other direction in the circumferential direction with respect to the first rotating element by abutting against the first arm, and a second stopper that faces the other direction in the circumferential direction and limits rotation of the second rotating element to the one direction in the circumferential direction with respect to the first rotating element by abutting against the second arm, and

the lining plate is provided with a cutout portion which is recessed radially outward between the first stopper and the second stopper, and is opened radially inward.

10. The damper according to claim 1 , wherein

the lining plate has a third sliding surface which faces the second direction and is surface-hardened, and

a radially outer edge of the third sliding surface is a curved edge or a chamfered edge.