Damping mechanism

1. A damping mechanism that generates a damping force in response to a liquid flow formed between a first liquid chamber and second liquid chamber, comprising:

a partitioning member separating the first liquid chamber and the second liquid chamber; and

a flow passage formed in the partitioning member to connect the first liquid chamber and the second liquid chamber, the flow passage comprising an odd number of through-holes greater than three which penetrate the partitioning member and are connected in series,

wherein the through-holes comprise:

a first through-hole which penetrates the partitioning member;

a second through-hole which penetrates the partitioning member in parallel with the first through-hole; and

an intermediate through-hole or an odd number of intermediate through-holes which penetrates the partitioning member in parallel with the first and second through-holes,

wherein the damping mechanism further comprises:

a first communicating groove formed in a surface of the partitioning member facing the first liquid chamber to connect the first through-hole and the intermediate through-hole or one of the intermediate through-holes;

a second communicating groove formed in a surface of the partitioning member facing the second liquid chamber to connect the second through-hole and the intermediate through-hole or one of the intermediate through-holes;

a first closing member which blocks the communicating groove from communicating with the first liquid chamber; and

a second closing member which blocks the second communicating groove from communicating with the second liquid chamber.

2. The damping mechanism as defined in claim 1 , comprising a plurality of flow passages, each of which comprises the first through-hole, the first communicating groove, the intermediate through-hole or the intermediate through-holes, the second communicating groove, and the second through-hole, to connect the first liquid chamber and the second liquid chamber.

3. The damping mechanism as defined in claim 2 , wherein the partitioning member has an annular groove facing the first liquid chamber to connect the second through-holes, and the first closing member has a hole portion connecting the annular groove and the first liquid chamber.

4. The damping mechanism as defined in claim 2 , wherein the partitioning member has a circular cross-sectional shape having a center, the second through-holes are located closer to the center of the partitioning member than the first through-hole, the second closing member is formed in a circular shape coaxial with the partitioning member and having an outer periphery, and the first through-holes have openings to the second liquid chamber on an outside of the outer periphery of the second closing member.

5. The damping mechanism as defined in claim 1 , wherein the number of the intermediate through-holes is an odd number greater than three, the damping mechanism further comprises a first intermediate communicating groove or first intermediate communicating grooves formed in the partitioning member facing the first liquid chamber to connect two of the intermediate through-holes. the first intermediate communicating groove or the first intermediate communicating grooves being blocked by the first closing member from communicating with the first liquid chamber, and a second intermediate communicating groove or second intermediate communicating grooves formed in the partitioning member facing the second liquid chamber to connect two of the intermediate through-holes, the second intermediate communicating groove or the second intermediate communicating grooves being blocked by the second closing member from communicating with the second liquid chamber, and the intermediate through-holes are connected in series via the first and second intermediate communicating grooves.

6. The damping mechanism as defined in claim 5 , wherein the total number of the first communicating groove, the second communicating groove, and the intermediate communicating groove or the intermediate communicating grooves is defined as (N−1)/2, where the total number of the first through-hole, the second through-hole, and the intermediate through-holes is N.

7. The damping mechanism as defined in claim 1 , wherein the first closing member comprises a leaf valve which allows the communicating groove or the communicating grooves facing the first liquid chamber to communicate with the first liquid chamber as a pressure in the second liquid chamber increases with respect to a pressure in the first liquid chamber.

8. The damping mechanism as defined in claim 1 , wherein the second closing member comprises a leaf valve which allows the communicating groove or the communicating grooves facing the second liquid chamber to communicate with the second liquid chamber as a pressure in the first liquid chamber increases with respect to a pressure in the second liquid chamber.

9. The damping mechanism as defined in claim 1 , wherein the partitioning member comprises a piston accommodated in a cylinder of a hydraulic shock absorber so as to slide within the cylinder in a direction of a cylinder axis, and all of the through-holes are formed in the partitioning member in parallel with the cylinder axis.