Liquid-sealed type vibration isolator

A liquid-sealed type vibration isolator comprising:

• a first fixture to be fixed to one of a vibration source side and a support side;
• a second fixture to be fixed to the other one of the vibration source side and the support side;
• a vibration-isolating base member made of an elastomer interposed between the first fixture and the second fixture;
• a main liquid chamber having liquid sealed therein and a chamber wall thereof defined partly of the vibration-isolating base member;
• at least one auxiliary liquid chamber having liquid sealed therein and a chamber wall thereof defined partly of a diaphragm formed of an elastomeric membrane;
• a first orifice flow channel configured to communicate the main liquid chamber and either one of the auxiliary liquid chambers;
• a second orifice flow channel tuned to a higher frequency range than the first orifice flow channel and configured to communicate any two of the main liquid chamber and the auxiliary liquid chambers;
• a partitioning member configured to partition the main liquid chamber and any one of the auxiliary liquid chambers and formed with the second orifice flow channel;
• and
• a valve member formed of an elastomeric membrane for opening and closing the second orifice flow channel,
• wherein the partitioning member includes a valve housing chamber configured to house and hold the valve member in a part of the second orifice flow channel so as to be orthogonal to the direction of flow in the flow channel,
• the valve member is held at an outer peripheral portion thereof between wall surfaces of the valve housing chamber, and includes inside the outer peripheral portion thereof a flexible membrane portion configured to be subjected to flexural deformation by the liquid flow in the second orifice flow channel and thereby close an opening of the second orifice flow channel to the valve housing chamber provided in the partitioning member, and
• the membrane portion includes a communication hole configured to bring the second orifice flow channel into communication at a position not being overlapped with the opening of the partitioning member to open the second orifice flow channel in a state in which the membrane portion is apart from the opening.