Damper

1. A damper, comprising:

a cylinder in which a working fluid is sealed;

a piston slidably fitted into the cylinder and configured to partition an inside of the cylinder into a first cylinder chamber and a second cylinder chamber;

a piston rod in which one end side is connected to the piston and an other end side extends to an outside of the cylinder;

a first passage in which the working fluid flows out from one of the cylinder chambers due to movement of the piston;

a second passage provided in parallel to the first passage;

a first damping force generation mechanism provided in the first passage to generate a damping force;

an annular case member having a bottomed cylindrical shape which penetrates a shaft-shaped member and has at least a portion of the second passage formed inside, wherein a recess is formed on a bottom part of the annular case member;

an annular disc which is disposed above the recess and penetrates the shaft-shaped member and is disposed to face the bottom part of the annular case member to be able to be bent so as to enter the recess by the working fluid in the annular case member;

a first chamber communicating with the first cylinder chamber and a second chamber communicating with the second cylinder chamber which are provided by the annular disc partitioning the inside of the annular case member;

a first through hole provided in the recess formed on the bottom part of the annular case member and configured to communicate with the second chamber;

a bypass passage provided in parallel to the first through hole and configured to allow communication between the first chamber and the second cylinder chamber; and

a second damping force generation mechanism provided in the bypass passage and configured to open a valve thereof when a pressure inside the first chamber reaches a predetermined pressure to generate a damping force.

2. The damper according to claim 1 , wherein the annular disc is of a floating type which is biased by a spring means.

3. The damper according to claim 1 , wherein the annular disc is of a clamp type which is partially clamped.

4. The damper according to claim 1 , wherein

the second damping force generation mechanism is disposed outside the annular case member to face the bottom part, and

a second through hole is provided in the bottom part to face the second damping force generation mechanism.

5. The damper according to claim 4 , wherein the first through hole is provided on an outer side of the second through hole in the bottom part.

6. The damper according to claim 4 , wherein the first through hole is provided on an inner side of the second through hole in the bottom part.

7. The damper according to claim 1 , wherein

valve opening of the first damping force generation mechanism is adjusted by a pressure of a case chamber, and

an introduction orifice is provided between the first passage and the case chamber.

8. The damper according to claim 7 , wherein a plurality of the introduction orifices are provided in series.

9. The damper according to claim 1 , wherein the recess has a shape in which a width in a radial direction of the recess becomes smaller as a depth increases.

10. The damper according to claim 1 , wherein the recess has a stopper surface recessed in an axial direction of the annular case member.

11. The damper according to claim 10 , wherein a cross section of the stopper surface in a plane including a central axis of the bottom part of the annular case member has a constant arc shape regardless of a circumferential position.

12. The damper according to claim 1 , wherein the first through hole is formed at a deepest bottom position of the recess.