| 摘要 |
A main liquid chamber communicates with a first auxiliary liquid chamber and a second auxiliary liquid chamber via a first limiting passage and a second limiting passage, respectively. The first and second auxiliary liquid chambers are located adjacent first and second air chambers via first and second diaphragms, respectively. As a solenoid valve is changed over, the second air chamber is made to communicate with the negative pressure of an engine or the with atmospheric pressure. The second liquid chamber is disposed in a hollow cylindrical member. When frequencies of vibrations are below a predetermined frequency, the negative pressure of the engine is transmitted to the second air chamber, causing the second diaphragm to be brought into close contact with and fixed to an inner wall of the second air chamber. As a result, a liquid passing through the first limiting passage absorbs the vibrations. When the frequencies of the vibrations become high, the first limiting passage becomes incapable of absorbing the vibrations, and the atmospheric pressure is imparted to the second air chamber. For this reason, the second diaphragm becomes deformable, so that the liquid passes through the second limiting passage to absorb the vibrations. In addition, a third auxiliary liquid chamber and accompanying third limiting passage can be provided to absorb high-frequency vibrations. The length of this third limiting passage is made shorter than that of the second limiting passage and the resonance of the liquid in the third limiting passage is made higher than that in the second limiting passage.
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