Hydraulic vibration isolation device

A hydraulic vibration isolation device comprising:

• an inner cylinder;
• an outer cylinder surrounding the inner cylinder axially parallel thereto;
• a vibration-isolating base body made of rubber-like elastomer interposed between the inner cylinder and the outer cylinder;
• an intermediate cylinder disposed between the inner cylinder and the outer cylinder;
• a first liquid chamber and a second liquid chamber situated interposing the inner cylinder therebetween;
• a main orifice through which to put the first liquid chamber and the second liquid chamber into communication with each other;
• a first sub-orifice for flowing a liquid through a first rubber valve only from the first liquid chamber to second liquid chamber;
• and
• a second sub-orifice for flowing the liquid through a second rubber valve only from the second liquid chamber to the first liquid chamber;
• wherein said intermediate cylinder includes a pair of ring-like fitting peripheral walls at axially both ends thereof, to which the outer cylinder is fitted, and a pair of joining walls situated to interpose the inner cylinder and disposed radially inwardly of the fitting peripheral walls to interconnect the pair of fitting peripheral walls;
• said vibration-isolating base body connects inner surfaces of the pair of joining walls and an outer peripheral surface of the inner cylinder opposed to the inner surfaces thereby to delimit the first liquid chamber and the second liquid chamber in the circumferential direction;
• end walls made of rubber-like elastomer are provided between the pair of fitting peripheral walls and the inner cylinder to form chamber walls of the first liquid chamber and the second liquid chamber at axial ends thereof;
• a first orifice-forming part in pressure contact with the inner peripheral surface of the outer cylinder is provided on a side of an outer surface of at least one of the pair of joining walls, and a second orifice-forming part in pressure contact with the inner peripheral surface of the outer cylinder is provided on a side of an outer surface of the other of the pair of joining walls;
• at least one of the first orifice-forming part and the second orifice-forming part is defined with a first sub-orifice channel extending in the circumferential direction, thereby forming the first sub-orifice between the first sub-orifice channel and the inner peripheral surface of the inner cylinder;
• at least one of the first orifice-forming part and the second orifice-forming part is defined with a second sub-orifice channel extending in the circumferential direction, thereby forming the second sub-orifice between the second sub-orifice channel and the inner peripheral surface of the inner cylinder;
• the first orifice-forming part and the second orifice-forming part are provided with respective fitting recessed portions extending in the circumferential direction;
• a first main orifice-forming member having a first main orifice channel on its outer peripheral surface communicating through a first opening with the first liquid chamber is disposed within the first liquid chamber, and a second main orifice-forming member having a second main orifice channel on its outer peripheral surface communicating through a second opening with the second liquid chamber is disposed within the second liquid chamber;
• the first main orifice-forming member and the second main orifice-forming member are provided, at respective circumferentially both ends, with fitting protrusions, the fitting protrusions being fitted in the fitting recessed portions and disposed to be spanned between the first and the second orifice-forming parts within the liquid chambers;
• the first main orifice-forming member and the second main orifice-forming member are at their respective outer peripheral surfaces in pressure contact with the inner peripheral surface of the outer cylinder, and the first main orifice channel and the second main orifice channel communicate with each other and are interconnected at the first orifice-forming part, whereby to form the main orifice.