Fluid-filled type vibration damping device

A fluid-filled type vibration damping device comprising:

• a first fluid chamber and a second fluid chamber respectively filled with non-compressible fluid and which experience relative pressure fluctuations during vibration input;
• an orifice passage through which the first fluid chamber and the second fluid chamber communicate with one another;
• an outside orifice member having a passage hole that defines an outside peripheral wall face of the orifice passage;
• an inside orifice member arranged inserted into the passage hole of the outside orifice member from one opening thereof and defining an inside peripheral wall face of the orifice passage;
• the orifice passage defined by a cylindrical gap formed between inside and outside peripheral faces of the outside orifice member and the inside orifice member;
• and
• an actuator adapted to adjust an insertion distance of the inside orifice member into the outside orifice member,
• wherein a passage length of the orifice passage is variable through adjustment with the actuator of the insertion distance of the inside orifice member into the outside orifice member,
• wherein the actuator is composed of an electric motor that is arranged such that a rotational driving force generated by the electric motor is applied to the inside orifice member via a screw mechanism as a reciprocating drive force to make an insertion/withdrawal displacement of the inside orifice member with respect to the outside orifice member,
• wherein the screw mechanism comprises an external thread member rotated by the electric motor and an internal thread portion provided on the inside orifice member, and the screw mechanism is provided with interlocking portions for preventing a rotation of the inside orifice member with respect to the outside orifice member, while permitting the insertion/withdrawal displacement of the inside orifice member with respect to the outside orifice member, and
• wherein a tuning frequency of the orifice passage is variable by changing the passage length of the orifice passage without changing a distance of the cylindrical gap between the inside and outside peripheral faces of the outside orifice member and the inside orifice member over an entire length of the orifice passage.