Vibration isolator with a diaphragm in a side wall

A vibration isolater for absorbing vibrations of different frequencies from a vibration-generating source, comprising:

• a hollow cylindrical member having therein a main liquid chamber to which the vibrations are transmitted;
• first-limiting passage constituting means for constituting a first limiting passage having one end communicating with said main liquid chamber;
• first-auxiliary-liquid-chamber constituting means for constituting a first auxiliary liquid chamber communicating with another end of said first limiting passage and capable of undergoing expansion and shrinkage;
• second-limiting-passage constituting means for constituting a second limiting passage having one end communicating with said main liquid chamber;
• second-auxiliary-wall constituting means disposed in said hollow cylindrical member and provided with an air chamber in an expandable and shrinkable second auxiliary liquid chamber which is formed within a side wall thereof communicating with another end of said second limiting passage via a diaphragm;
• and
• negative-pressure means communicating with said air chamber for fixing said diaphragm so as to prevent the expansion and shrinkage of said second auxiliary liquid chamber.

A vibration isolator for absorbing and attenuating vibrations from a vibration-generating portion, comprising:

• a mounting member connected to one of said vibration-generating portion and a vibrating-receiving portion;
• a hollow cylindrical member connected to the other one of said vibration-generating portion and said vibrating-receiving portion;
• a resilient member connected to said mounting member, and resilient member being disposed to close one opening of said hollow cylindrical member and being adapted to be deformed during the occurrence of the vibrations;
• a first diaphragm for closing another opening of said hollow cylindrical member;
• a partition member disposed at an inner side of said hollow cylindrical member, said partition member partitioning an inner space of said hollow cylindrical member;
• an expandable and shrinkable main liquid chamber disposed within said hollow cylindrical member between said resilient member and said partition member;
• a first auxiliary liquid chamber disposed within said hollow cylindrical member between said first diaphragm and said partition member;
• a first limiting passage connecting said main liquid chamber and said first auxiliary liquid chamber thereby allowing communication with each other;
• a first air chamber disposed facing a side of said first diaphragm opposite to a side thereof where said first auxiliary liquid chamber is disposed;
• a second auxiliary liquid chamber formed within a side wall of said hollow cylindrical member;
• a second diaphragm constituting a part of a partition wall of said second auxiliary liquid chamber;
• a second air chamber disposed on a side of said second diaphragm opposite to a side thereof where said second auxiliary liquid chamber is disposed, said second air chamber being arranged such that when an interior thereof is set under negative pressure, said second air chamber causes said second diaphragm to be brought into close contact with an inner wall surface thereof causing said second air chamber to virtually disappear and preventing the movement of said second diaphragm;
• a second limiting passage connecting said main liquid chamber and said second auxiliary liquid chamber thereby allowing communication with each other;
• negative-pressure means for setting the interior of said second air chamber under negative pressure;
• and
• control means for controlling said negative-pressure means by causing said negative-pressure means to be actuated in correspondence with at least one of a vehicle speed and an engine speed of a vehicle.