Vibration isolating apparatus

DETAILED DESCRIPTION Accordingly, an object of the present invention is to provide a vibration isolating apparatus which is capable of obtaining an effective attenuating effect in a wide range of frequencies, thereby overcoming the above-described drawback of the conventional art.
To this end, in accordance with the present invention, there is provided a vibration isolating apparatus comprising: a first cylindrical member supported by one of a vibration producing portion and a vibration receiving portion; a second cylindrical member supported by the other of the vibration producing portion and the vibration receiving portion; a liquid chamber provided between the first cylindrical member and the second cylindrical member and partitioned into a main liquid chamber and an auxiliary liquid chamber; a resilient diaphragm serving as a partition wall of the auxiliary liquid chamber and adapted to expand or shrink the auxiliary liquid chamber; an orifice member interposed between the first cylindrical member and the second cylindrical member, the orifice member having therein an orifice constituted by a passage which has a rectangular cross section with its long side portion formed to be not less than two times a short side portion thereof, the orifice allowing the main liquid chamber and the auxiliary liquid chamber to communicate with each other; a pair of electrode plates provided in opposing long side portions of the passage, respectively; and an electrorheological fluid which is filled in the liquid chamber and whose viscosity changes with the magnitude of an electric field applied thereto.
In the present invention having the above-described arrangement, vibrations are absorbed by resistance occurring when the electrorheological fluid passes through the aforementioned passage, in the same way as a generally employed vibration isolating apparatus in cases where the electrode plates are not energized.
In addition, if a different electric field is produced by the electrode plates, the viscosity of the electrorheological fluid changes in correspondence with that electric field, so that the passage resistance at the orifice changes