Patent ID: 8282086
Filing Date: 2012-10-09
Classification: B60K,F16F

Abstract:
1. A vibration isolator comprising: a first attaching member connected to one of a vibration-producing part and a vibration-receiving part; a second attaching member connected to the other of the vibration-producing part and the vibration-receiving part; an elastic body arranged between the first attaching member and the second attaching member; a main fluid chamber which is filled with a fluid with the elastic body being used as a part of partition and the internal volume of which changes along with the elastic deformation of the elastic body; a sub-fluid chamber which is filled with the fluid and the internal volume of which is capable of increasing and decreasing; a first restriction passage which causes the main fluid chamber and the sub-fluid chamber to communicate with each other; a second restriction passage which causes the main fluid chamber and the sub-fluid chamber to communicate with each other and has fluid flow resistance smaller than that of the first restriction passage, wherein a part on the main fluid chamber side of the first restriction passage is formed as a common orifice part forming a part of the second restriction passage; a cylinder chamber which is provided between the main fluid chamber and the sub-fluid chamber and is filled with the fluid; a plunger member which divides the cylinder chamber into an orifice space which forms a part of the second restriction passage and communicates with the sub-fluid chamber and a pressurization space isolated from the second restriction passage, and is capable of moving between a predetermined opening position and closing position along the expanding/contracting direction of the orifice space and the pressurization space; an orifice opening which is provided so as to face to the orifice space to cause the orifice space to communicate with the second restriction passage; an urging member for urging the plunger member to the opening position side to decrease the pressurization space; a fluid pressure releasing path for allowing the fluid in the pressurization space to flow out into the orifice space or the sub-fluid chamber when the plunger member is returned to the opening position by the urging force of the urging member; a check valve which is arranged between the main fluid chamber and the pressurization space and is capable of allowing the fluid to flow out only in one direction between the main fluid chamber and the pressurization space along with a fluid pressure change in the main fluid chamber; a shaft accommodating hole provided in the plunger member so as to penetrate in the expanding/contracting direction; and a holder member for a valve element of the check valve, which is provided with a guide shaft inserted in the shaft accommodating hole so as to be relatively slidable, the width of a first opening along the opening longitudinal direction of the orifice opening in parallel with the expanding/contracting direction being set so as to be narrower than the width of a second opening along the opening transverse direction intersecting with the opening longitudinal direction, the plunger member closing the orifice opening when being moved to the closing position against the urging force of the urging member by the fluid pressure in the pressurization space, and opens the orifice opening when being returned to the opening position by the urging force of the urging member, and when the maximum tilt angle of the plunger member with respect to the expanding/contracting direction, which is calculated according to a difference between the inside diameter of the shaft accommodating hole and the outside diameter of the guide shaft, is taken as qMAX, a difference DMIN between the inside diameter of the cylinder chamber and the outside diameter of the plunger member is set so that any portion on the outer peripheral surface of the plunger member keeps a clearance of 0 mm or larger between the outer peripheral surface of the plunger member and the inner peripheral surface of the cylinder chamber in a state in which the plunger member tilts at the maximum tilt angle qMAX.