Liquid-filled type vibration damping structure

Abstract

A liquid-filled type vibration damping structure consisting of a liquid-filled vibration isolator and a bracket member in which the liquid-filled vibration isolator comprises first and second frames each to be mounted on a vibration source side such as power unit and on a vehicle body side, a resilient member provided between the first and second frames, a baffle member secured on the first frame and dividing the internal space surrounded by the resilient member, a diaphragm and one of the frames into two liquid chambers, said baffle member further having a ring-shaped orifice portion so as to damp a low frequency band vibration through the orifice portion. The liquid-filled vibration isolator further comprises a movable plate placed within an enclosure formed between the baffle member and at least one auxiliary plate having an aperture at the center thereof respectively so as to communicate with the two liquid chamber and to damp a high frequency band vibration, and at least one mass body attached to the resilient member. With this construction, the residual frequency peak of a first vibration transmission characteristic caused by the movable plate according to the prior art can be effectively cancelled by a bottoming frequency of a second vibration transmission characteristic due to the mass body and the resilient member, in accordance with the adjustment of the angle of inclination of the bracket member and the mass body, thereby preventing a booming sound or confined sound inside a vehicle from occuring and obtaining quietness inside the vehicle.