Vibration isolation device

1. A vibration isolation device comprising:

a cylindrical first mounting member connected to one of a vibration generating unit and a vibration receiving unit and a second mounting member connected to the other thereof;

an elastic body connecting the first mounting member and the second mounting member; and

a partition member which partitions a liquid chamber in the first mounting member into a main liquid chamber including the elastic body as a part of a partition wall thereof and a sub liquid chamber, wherein

the partition member includes:

a membrane which forms a part of the partition wall of the main liquid chamber; and

a first orifice passage which communicates with the main liquid chamber and opens toward the sub liquid chamber,

a flow resistance of a liquid in a portion positioned on the main liquid chamber side and a flow resistance of a liquid in a portion positioned on the sub liquid chamber side are different from each other in the first orifice passage,

the first orifice passage is constituted by a first orifice groove positioned on the main liquid chamber side and extending in a circumferential direction, a second orifice groove positioned on the sub liquid chamber side and extending in the circumferential direction, and a connection hole, and

the connection hole connects in a radial direction an end portion on one side in the circumferential direction of the first orifice groove and an end portion on one side in the circumferential direction of the second orifice groove, the end portion on the one side in the circumferential direction of the first orifice groove and the end portion on the one side in the circumferential direction of the second groove being disposed at equivalent circumferential positions.

2. The vibration isolation device according to claim 1 , wherein the flow resistance of the liquid in the portion positioned on the main liquid chamber side is higher than the flow resistance of the liquid in the portion positioned on the sub liquid chamber side in the first orifice passage.

3. The vibration isolation device according to claim 2 , wherein the partition wall includes:

an intermediate chamber positioned on a side opposite to the main liquid chamber with the membrane sandwiched therebetween and having the membrane as a part of a partition wall thereof; and

a second orifice passage which is configured to allow the intermediate chamber and the sub liquid chamber to communicate with each other.

4. The vibration isolation device according to claim 3 , wherein an opening portion of the second orifice passage on the intermediate chamber side faces the membrane.

5. The vibration isolation device according to claim 4 , wherein the first orifice passage opens toward the intermediate chamber, and an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

6. The vibration isolation device according to claim 3 , wherein

the first orifice passage opens toward the intermediate chamber, and

an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

7. The vibration isolation device according to claim 1 , wherein the flow resistance of the liquid in the portion positioned on the sub liquid chamber side is higher than the flow resistance of the liquid in the portion positioned on the main liquid chamber side in the first orifice passage.

8. The vibration isolation device according to claim 7 , wherein the partition wall includes:

an intermediate chamber positioned on a side opposite to the main liquid chamber with the membrane sandwiched therebetween and having the membrane as a part of a partition wall thereof; and

a second orifice passage which is configured to allow the intermediate chamber and the sub liquid chamber to communicate with each other.

9. The vibration isolation device according to claim 8 , wherein an opening portion of the second orifice passage on the intermediate chamber side faces the membrane.

10. The vibration isolation device according to claim 9 , wherein

the first orifice passage opens toward the intermediate chamber, and

an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

11. The vibration isolation device according to claim 8 , wherein the first orifice passage opens toward the intermediate chamber, and an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

12. The vibration isolation device according to claim 1 , wherein the partition wall includes:

an intermediate chamber positioned on a side opposite to the main liquid chamber with the membrane sandwiched therebetween and having the membrane as a part of a partition wall thereof; and

a second orifice passage which is configured to allow the intermediate chamber and the sub liquid chamber to communicate with each other.

13. The vibration isolation device according to claim 12 , wherein an opening portion of the second orifice passage on the intermediate chamber side faces the membrane.

14. The vibration isolation device according to claim 13 , wherein

the first orifice passage opens toward the intermediate chamber, and

an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

15. The vibration isolation device according to claim 14 , wherein

the first orifice passage opens toward the intermediate chamber, and

an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

16. The vibration isolation device according to claim 13 , wherein a cross-sectional area of the intermediate chamber in a direction perpendicular to the opening direction in which the second orifice passage opens toward the intermediate chamber is larger than a flow path cross-sectional area of a portion of the first orifice passage on the intermediate chamber side.

17. The vibration isolation device according to claim 12 , wherein

the first orifice passage opens toward the intermediate chamber, and

an opening direction thereof intersects an opening direction in which the second orifice passage opens toward the intermediate chamber.

18. The vibration isolation device according to claim 17 , wherein a cross-sectional area of the intermediate chamber in a direction perpendicular to the opening direction in which the second orifice passage opens toward the intermediate chamber is larger than a flow path cross-sectional area of a portion of the first orifice passage on the intermediate chamber side.

19. The vibration isolation device according to claim 12 , wherein a cross-sectional area of the intermediate chamber in a direction perpendicular to the opening direction in which the second orifice passage opens toward the intermediate chamber is larger than a flow path cross-sectional area of a portion of the first orifice passage on the intermediate chamber side.

20. The vibration isolation device according to claim 12 , wherein a portion of the first orifice passage on the intermediate chamber side is formed as a passage of which a flow path length is larger than a flow path diameter.