Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2001-03-28
2002-03-05
Schwartz, Christopher P. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140150
Reexamination Certificate
active
06352249
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application Nos. 2000-94916 and 2000-253274 filed on Mar. 30, 2000 and Aug. 24, 2000, respectively, are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a fluid-filled vibration-damping device which has a fluid chamber or chambers filled with a non-compressible fluid. More particularly, the present invention is concerned with a pneumatically operated fluid-filled vibration-damping device which includes a fluid chamber partially defined by one of opposite surfaces of an elastic oscillating plate and an oscillating air chamber partially defined by the other surface of the elastic oscillating plate, and which is operable by applying a suitable air pressure change to the oscillating air chamber so that the vibration damping device exhibits desirably controlled damping characteristics thereof.
2. Description of the Related Art
As one type of a vibration damper such as a vibration damping bushing or a vibration damping mount, for flexibly connecting two members in a vibration system or mounting one of the two members on the other member in a vibration damping fashion, there is known a pneumatically operated fluid-filled vibration damping device, as disclosed in Japanese Laid-Open Publication No. JP-A-10-184770. Such a known pneumatically operated fluid-filled vibration damping device includes: a first and a second mounting members, which are spaced apart from each other; an elastic body elastically connecting the first and second mounting members and partially defining a primary fluid chamber filled with a non-compressible fluid; a flexible diaphragm partially defining an auxiliary fluid chamber filled with the non-compressible fluid and having a variable volume; a partition member fixed to the second mounting member such that the primary fluid chamber is disposed on one of opposite sides of the partition member and the auxiliary fluid chamber is disposed on the other side of the partition member; means for defining a first orifice passage for fluid communication between the primary and auxiliary fluid chambers; and an elastic oscillating plate partially defining on one of opposite sides thereof the pressure receiving chamber and on the other side thereof an oscillating air chamber, to which a suitably controlled periodic change of an air pressure is applied to the oscillating air chamber so that the elastic oscillating plate is oscillated by an oscillating force having a frequency corresponding to the frequency of the vibration to be damped. This type of the vibration-damping device is capable of controlling its vibration damping characteristics by adjusting the frequency or other factors of the periodic change of the air pressure applied to the oscillating air chamber. Therefore, this type of the vibration damping device has been suitably applied to vibration dampers such as an engine mount, which require to damp input vibrations whose frequencies and other factors are variable.
As is understood from the above-indicated publication, the known vibration damping device uses a disk-like shaped rubber elastic plate as the elastic oscillating plate which is oscillated to transmit the oscillating force caused by the periodic change of the air pressure in the oscillating air chamber to the primary fluid chamber to cause a pressure change of the fluid in the primary fluid chamber. The rubber elastic plate is fixedly supported at its peripheral portion by a member on the side of the second mounting member, and the first orifice member is disposed radially outwardly of the rubber plate for fluid communication between the primary and auxiliary fluid chambers.
In the known vibration damping device, the rubber elastic plate is desirably required to have a relatively large area so that the vibration damping device exhibits a high damping effect even in the case where the vibration to be damped has a relatively large vibrational energy.
However, the known vibration damping device constructed as described above needs to leave a space for disposing the first orifice passage at the radially outward portion of the rubber elastic plate, making it difficult to increase a diameter of the rubber elastic plate, resulting in difficulty in obtaining a sufficiently large area of the elastic rubber plate within a limited tolerable range of the outer diameter of the vibration damper.
Moreover, the rubber elastic plate whose diameter is increased to provide a sufficiently large area thereof is prone to be oscillated with a relatively large amplitude at its central portion. This may cause interference between the rubber elastic plate and other members incorporated within the vibration damper, resulting in deterioration of damping capacity of the device, generation of noises, and undesirable damages of the rubber elastic plate and the other members. In order to avoid the above-indicated interference between the rubber elastic plate and the other incorporated members, the vibration-damping device is inevitably made large in size.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a pneumatically operated fluid-filled vibration damping device which has a novel structure suitable for obtaining a sufficiently large area of an elastic oscillating plate while limiting the size of the device, and suitable for limiting an amount of maximum displacement of the elastic oscillating plate upon oscillation thereof.
The above and other objects of this invention may be attained according to the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. It is to be understood that the principle of the invention is not limited to those modes of the invention and combinations of the technical features, but may otherwise be recognized based on the thought of the present invention that disclosed in the whole specification and drawings or that may be recognized by those skilled in the art in the light of the disclosure in the whole specification and drawings.
(1) A fluid-filled vibration damping device comprising: a first and a second mounting member which are spaced apart from each other; an elastic body elastically connecting the first and second mounting members and partially defining a primary fluid chamber filled with a non-compressible fluid; a flexible diaphragm partially defining an auxiliary fluid chamber filled with the non-compressible fluid and whose volume is variable; a first partition wall fixed to the second mounting member and partially defining the primary fluid chamber on one of opposite sides thereof and the auxiliary fluid chamber on the other side thereof; a first orifice passage formed at a central portion of the first partition wall for fluid communication between the primary and auxiliary fluid chamber; and an elastic oscillating plate having an annular or a cylindrical shape and disposed radially outwardly of the orifice passage so as to continuously extend in a circumferential direction thereof, the elastic oscillating plate partially defining the primary fluid chamber on one of opposite sides thereof and an oscillating air chamber on the other side thereof, the oscillating air chamber being applied with a periodic change of an air pressure so as to apply to the elastic oscillating plate an oscillating force whose frequency is corresponding to that of vibrations to be damped, whereby the vibration damping device exhibits an active damping effect with respect to the vibrations to be damped.
In the fluid-filled vibration damping device constructed according to the present mode of the invention, the first orifice passage is formed in the central portion of the first partition wall and the annular or cylindrical elastic oscillating plate is disposed radially outwardly of the first orifice passage, making it possible to increase a diameter of the el
Ichikawa Hiroyuki
Muramatsu Atsushi
Beyer Weaver & Thomas LLP
Schwartz Christopher P.
Tokai Rubber Industries Ltd.
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