Anti-vibration device

An anti-vibration device comprising:

• a tubular first attachment member that is coupled to any one of a vibration generating part and a vibration receiving part, and a second attachment member that is coupled to the other thereof;
• an elastic body that couples the first attachment member and the second attachment member to each other;
• and
• a partition member that partitions a liquid chamber in the first attachment member into a main liquid chamber having the elastic body in a portion of a partition wall thereof, and an auxiliary liquid chamber,
• wherein the partition member includes
• a membrane that forms a portion of the partition wall of the main liquid chamber, and
• an orifice passage that extends from the main liquid chamber toward the auxiliary liquid chamber,
• the orifice passage includes a main liquid chamber-side passage that is located on the main liquid chamber side and an auxiliary liquid chamber-side passage that extends from the main liquid chamber-side passage toward the auxiliary liquid chamber,
• the main liquid chamber-side passage and the auxiliary liquid chamber-side passage extend in a circumferential direction and are disposed at mutually different radial positions,
• a flow direction in the main liquid chamber-side passage and a flow direction in the auxiliary liquid chamber-side passage are opposite to each other when liquid flows through the orifice passage,
• a channel cross-sectional shape in at least one passage of the main liquid chamber-side passage and the auxiliary liquid chamber-side passage is a laterally long flat shape that is short in an axial direction along a central axis of the first attachment member and long in a radial direction, and
• a ratio of a radial size to an axial size in the one passage is larger than the ratio in the other passage of the main liquid chamber-side passage and the auxiliary liquid chamber-side passage.