1. Field of the Invention
The present invention relates to a vibration isolating device having a liquid chamber which is a space defined mainly by a vibration absorbing main body and a flexible membrane and in which a liquid is charged, the liquid chamber being divided into liquid sub-chambers which communicate through a passage, and a method for manufacturing the vibration isolating device.
2. Description of the Prior Art
Among the conventional vibration isolating devices of this kind, a vibration isolating device is well known which comprises an annular vibration absorbing main body made of an elastic material containing a natural rubber having a low loss factor and which is concave at the top thereof and also has attached on the outer circumference thereof a clamping ring to which a top plate is fixed by caulking, a receptacle having an arch-like sectional shape being attached on the inner bottom circumference of the vibration absorbing main body, and a flexible membrane disposed along the bottom surface of the receptacle and having the circumferential edge sandwiched between the receptacle and a bottom plate. There is formed in the top of the receptacle an orifice which provides communication between the liquid chamber formed above the concavity of the vibration absorbing main body and the liquid chamber between the receptacle and flexible membrane (Japanese Utility Model Provisional Publication No. 110344/82 and Japanese Patent Provisional Publication No. 70240/86).
The above mentioned conventional vibration isolating device is not of a so-called bush type structure having inner and outer cylinders, and its structure is not suitable for improving the damping effect by lengthening the orifice.