Liquid-sealed antivibration device

A liquid-sealed antivibration device comprising:

• a cup-shaped main body fitting having an open top, said main body fitting being adapted to be connected to a support supporting a vibration source;
• a boss fitting arranged inboard of the main body fitting in its axial center part, said boss fitting being adapted to be connected to the vibration source;
• a vibration-isolating base of rubber elastomer interconnecting the main body fitting and the boss fitting, said vibration-isolating base being deformed in accordance with vibrations from the vibration source via the boss fitting;
• a diaphragm of a rubber membrane connected to the open top of the main body fitting to close the open top;
• a partition plate member partitioning an interior room enclosed by the main body fitting, the boss fitting, the vibration-isolating base, and the diaphragm, into a main liquid chamber on the boss fitting side and a subsidiary chamber on the diaphragm side, wherein a liquid is sealed in the interior room, said partition plate member including an elastic membrane at its central part, said main liquid chamber and said subsidiary chamber communicating through a first orifice disposed at a periphery of the elastic membrane;
• and
• a central plate provided over the elastic membrane and partitioning the subsidiary chamber into a first subsidiary chamber on the diaphragm side and a second subsidiary chamber on the elastic membrane, said central plate having a single second orifice for muffled sound through which the first subsidiary chamber and the second subsidiary chamber communicate, wherein the liquid moves between the main liquid chamber and the first subsidiary chamber through the first orifice and between the first subsidiary chamber and the second subsidiary chamber through the second orifice as the vibration-isolating base is deformed due to vibrations from the vibration source, wherein an opening as the second orifice, which the orifice member has on its central plate section, is made eccentric at an opposite side to the location of a communication Part from the first orifice at an outer circumferential Part of the orifice member to the first subsidiary chamber,
• said liquid-sealed antivibration device further comprising a cylindrical member to which the diaphragm is bonded by vulcanization, said cylindrical member being fastened to an upper extremity of the main body fitting and covered with a rubber portion, wherein the central plate further comprises a blocking wall portion formed outward from the periphery of the central plate, said blocking wall attaching the cylindrical member and forming the first orifice in a ring shape between the blocking wall and the partitioning plate member, wherein the blocking wall has an opening through which the first subsidiary chamber and the first orifice communicate.

A liquid-sealed antivibration device comprising a cylindrical main body fitting assuming a generally cup shape and having an open top, a boss fitting arranged inboard of the main body fitting in its axial center part, a vibration-isolating base of rubber elastomer interconnecting a lower part of the main body fitting and the boss fitting, a diaphragm of a rubber membrane connected to the main body fitting at its upper extremity so as to cover the open top, an interior room enclosed by the cylindrical main body fitting, the boss fitting, the vibration-isolating base, and the diaphragm and sealed with a liquid, and a partition element arranged between the vibration-isolating base and the diaphragm to compart the interior room into a main liquid chamber on the boss fitting side and a first subsidiary chamber on the diaphragm side, both chambers communicating through an orifice with each other,

• wherein the partition element includes a partition plate member having an elastic membrane at the central part of the partition plate member and an orifice member disposed on the first subsidiary chamber side so as to contact with a peripheral edge portion of the elastic membrane in an opposed manner thereto;
• a first orifice of a generally ring shape is formed by the orifice member, an outer peripheral portion of the partition plate member and a cylindrical rubber portion linking to the diaphragm;
• a space enclosed by a central plate section of the orifice member and a top surface of the partition plate member is formed as a second subsidiary liquid chamber;
• the central plate section of the orifice member is formed with an opening as a second orifice for a muffled sound communicating from the first subsidiary chamber to the second subsidiary chamber, wherein the first orifice is formed in such that a part of its circumferential path enclosed by outer peripheral portions of the partition plate member and the orifice member and the cylindrical rubber portion is closed by a blocking wall portion;
• the blocking wall portion is formed by a part of the orifice member and a rubber portion adhered by vulcanization to the partition plate member.

A liquid-sealed antivibration device comprising:

• a cup-shaped main body fitting having an open top, said main body fitting being adapted to be connected to a support supporting a vibration source;
• a boss fitting arranged inboard of the main body fitting in its axial center part, said boss fitting being adapted to be connected to the vibration source;
• a vibration-isolating base of rubber elastomer interconnecting the main body fitting and the boss fitting, said vibration-isolating base being deformed in accordance with vibrations from the vibration source via the boss fitting;
• a diaphragm of a rubber membrane connected to the open top of the main body fitting to close the open top;
• a partition plate member partitioning an interior room enclosed by the main body fitting, the boss fitting, the vibration-isolating base, and the diaphragm, into a main liquid chamber on the boss fitting side and a subsidiary chamber on the diaphragm side, wherein a liquid is sealed in the interior room, said partition plate member including an elastic membrane at its central part, said main liquid chamber and said subsidiary chamber communicating through a first orifice disposed at a periphery of the elastic membrane;
• a central plate provided over the elastic membrane and partitioning the subsidiary chamber into a first subsidiary chamber on the diaphragm side and a second subsidiary chamber on the elastic membrane, said central plate having a second orifice for muffled sound through which the first subsidiary chamber and the second subsidiary chamber communicate, wherein the liquid moves between the main liquid chamber and the first subsidiary chamber through the first orifice and between the first subsidiary chamber and the second subsidiary chamber through the second orifice as the vibration-isolating base is deformed due to vibrations from the vibration source;
• and
• a cylindrical member to which the diaphragm is bonded by vulcanization, said cylindrical member being fastened to an upper extremity of the main body fitting and covered with a rubber portion,
• wherein the central plate further comprises a blocking wall portion formed outward from the periphery of the central plate, said blocking wall attaching the cylindrical member and forming the first orifice in a ring shape between the blocking wall and the partitioning plate member, wherein the blocking wall has an opening through which the first subsidiary chamber and the first orifice communicate.