Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2000-01-31
2002-06-18
Dickson, Paul N. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140130, C267S140150
Reexamination Certificate
active
06406010
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a fluid-filled active vibration damping device which actively damps the vibration of an object by controlling the pressure of non-compressible fluid filling a pressure receiving chamber of the damping device, and in particular to such a fluid-filled active vibration damping device which is suitably used as an engine mount or a vibration damper in an automotive vehicle.
2. Related Art Statement
For damping vibration (including noise due to the vibration) of an object to be damped, such as the body or other members of an automotive vehicle that are subject to vibration, there have been various vibration damping devices such as a vibration damping connector and a vibration damper. The vibration damping connector, such as an engine mount, is interposed between a vibration source and an object whose vibration is to be damped, in order to damp the vibration to be transmitted from the vibration source to the object. The vibration damper, such as a dynamic damper, is attached directly to the object to absorb or damp the vibration of the object.
In this background, there has been proposed a fluid-filled active vibration damping device, as an example of such a vibration damping device as described above, as disclosed in Japanese Patent Applications TOKU-KAI-HEI No. 2-42228 and No. 9-49541 and Japanese Patents No. 2510914 and No. 2510925. Such a fluid-filled active vibration damping device includes (a) an elastic body which is elastically deformed when a vibration is input to the damping device and which partially defines a pressure receiving chamber filled with a non-compressible fluid; (b) an oscillating body which partially defines the pressure receiving chamber; and (c) a drive device which oscillates the oscillating body, so as to control a pressure of the non-compressible fluid in the pressure receiving chamber. In this vibration damping device, the pressure of the non-compressible fluid in the pressure receiving chamber is so controlled as to adjust the vibration damping characteristics of the damping device and thereby exhibit an active vibration damping effect, or to generate a controlled oscillating force and thereby actively damp the vibration of an object.
Meanwhile, in the vibration damping device constructed as described above, it is required that an output member of the drive be connected to the oscillating body, in order to transmit the output force of the drive device to the oscillating body. To this end, it has conventionally been practiced, as disclosed in the above-indicated publications, that the output member of the drive device is directly fixed to the oscillating body with a bolt, by press-fitting, or by caulking.
However, each of the above-indicated fixing methods has the problem that to fix the output member to the oscillating body is cumbersome, and accordingly is not suitable for the mass production of vibration damping devices. In addition, when the output member is fixed to the oscillating body, external forces are applied to the oscillating body, so that a large deformation may be produced in the oscillating body or a large strain may be left in the same. This problem leads to decreasing the life expectancy of those elements or lowering the accuracy of assembling of the same. Moreover, the defective assembling of the output member and the oscillating body leads to unstable accuracy of the products, which in turn leads to unstable performance of the same. Furthermore, the above-indicated fixing methods cannot assure that the output member remains fixed to the oscillating body with a sufficiently great strength for a long period of use.
For example, the bolt-using fixing method has the problem that it needs the technique and control to maintain a constant bolt-fastening torque and, in some cases, needs a mechanism for locking a bolt-loosening preventing screw, and the problem that to screw the bolt is cumbersome and time-consuming. The press-fitting fixing method has the problem that it needs a high accuracy of control of dimensions of the elements, in order to obtain stably sufficiently great fixing strength and reliability, and the problem that each element needs a sufficiently great strength to stand the load applied thereto upon press-fitting. The caulking fixing method has the problem that it needs a large-size caulking device and the problem that each element needs a sufficiently great strength to stand the load applied thereto upon caulking. In each of the above-indicated fixing methods, external forces, such as screwing force or press-fitting force, are inevitably applied to the oscillating body and accordingly strains are left in the same, so that the accuracy of dimensions of the oscillating body and the life expectancy of the same may be lowered.
There is also known a vibration damping device which additionally includes (d) a flexible diaphragm which partially defines an equilibrium chamber which is provided on one of both sides of the oscillating body that is opposite to the other side thereof on which the pressure receiving chamber is provided, the equilibrium chamber being filled with the non-compressible fluid, a volume of the equilibrium chamber being changed by deformation of the flexible diaphragm; and (e) an orifice for fluid communication between the pressure receiving chamber and the equilibrium chamber. This damping device additionally exhibits a passive vibration damping effect based on the resonance of the fluid flowing through the orifice. In this case, since, the pressure receiving chamber and the equilibrium chamber, each filled with the non-compressible fluid, are provided on both sides of the oscillating body, respectively, it is very difficult to fix directly the output member of the drive device to the oscillating body, in view of not only the structure of the damping device but also the fixing operation itself.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a fluid-filled active vibration damping device including a novel drive-force transmitting structure which can transmit, with high durability and reliability, a drive force of a drive device to an oscillating body, and which can be simply constructed and assembled.
To this end, the present invention provides a fluid-filled active vibration damping device which has one or more of the technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (8). Any technical feature which includes another feature shall do so by referring, at the beginning, to the parenthesized sequential number given to that feature. Thus, two or more of the following technical features may be combined, if appropriate. Each technical feature may be accompanied by a supplemental explanation, as needed. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited. Rather, the concept of the present invention should be understood based on the entire description of the specification and the entire illustration of the drawings.
(1) According to a first feature of the present invention, there is provided a fluid-filled active vibration damping device, comprising an elastic body which is elastically deformed when a vibration is input to the damping device and which partially defines a pressure receiving chamber as a portion of a fluid chamber filled with a non-compressible fluid; an oscillating body which partially defines the pressure receiving chamber; a drive device which oscillates the oscillating body, so as to control a pressure of the non-compressible fluid in the pressure receiving chamber, the drive device comprising an output member which is formed independent of the oscillating body and which is movable in a direction of oscillation of the oscillating body; a first biasing device which biases the oscillating body toward the output member of the drive device; and a second biasing device which biases the output member of t
Goto Katsuhiro
Hagino Yoshihiko
Yano Katsuhisa
Yoshida Takashi
Burch Melody M.
Burr & Brown
Dickson Paul N.
Tokai Rubber Industries Ltd.
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