Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-12-01
2001-11-06
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S219000
Reexamination Certificate
active
06311963
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid-filled vibration damping device which exhibits a vibration damping effect based on flows of a non-compressible fluid enclosed therein, and which is particularly suitable for use as, e.g., automotive-vehicle engine mounts, body mounts, and differential mounts.
2. Related Art Statement
There is known a fluid-filled vibration damping device as a sort of vibration damping connecting or supporting device that is interposed between constituent members of a vibration transmitting system. The fluid-filled vibration damping device includes a first mounting member; a second mounting member including a tubular portion having an end open toward the first mounting member, the first and second mounting members being spaced from, and opposed to, each other; and an elastic rubber body which elastically connects the first and second mounting members to each other, and which fluid-tightly closes the open end of the tubular portion of the second mounting member and cooperates with the tubular portion to define a fluid chamber filled with a non-compressible fluid. When a vibrational load is applied to the vibration damping device, it exhibits a vibration damping effect based on flows of the fluid in the fluid chamber, in particular, resonance of the fluid.
Meanwhile, there has been proposed another fluid-filled vibration damping device which includes, in addition to the above-indicated members, a working or umbrella-shaped member which is supported by the first mounting member such that the umbrella member extends, in the fluid chamber, in a direction substantially perpendicular to a central axis of the tubular portion of the second mounting member, and thereby divides the fluid chamber into two divided chambers which are located on opposite sides of the umbrella member, respectively, and which are communicated with each other via a fluid-flow restricting passage defined by at least the umbrella member.
To the second fluid-filled vibration damping device including the umbrella member, a main vibrational load is applied in a direction in which the first and second mounting members are opposed to each other, i.e., a direction parallel to the central axis of the tubular portion of the second mounting member. Upon application of the main vibrational load to the vibration damping device, the umbrella member is reciprocatively moved in the fluid chamber, so that the fluid flows through the fluid-flow restricting passage. The vibration damping device can exhibit a vibration damping effect based on the flows of the fluid through the restricting passage, in particular, the resonance of the fluid.
However, even in the second fluid-filled vibration damping device, the vibration damping effect based on the flows of the fluid through the restricting passage defined by the umbrella member is not satisfactory yet and, in some cases, the vibration damping device cannot exhibit a low dynamic spring effect to a desirable degree.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a fluid-filled vibration damping device which has an improved structure for exhibiting an excellent vibration damping effect based on flows of a non-compressible fluid enclosed in a fluid chamber.
The present invention provides a fluid-filled 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 (16). Any technical feature which includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to that technical 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 combinations thereof are just examples to which the present invention is by no means limited. Rather, the concept of the present invention should be construed based on the overall description of the specification and the drawings.
(1) According to a first feature of the present invention, there is provided a fluid-filled vibration damping device comprising a first mounting member; a second mounting member including a tubular portion having an end open toward the first mounting member, the first and second mounting members being spaced from, and opposed to, each other; an elastic rubber body which elastically connects the first and second mounting members to each other, and which fluid-tightly closes the open end of the tubular portion of the second mounting member and cooperates with the tubular portion to define a fluid chamber filled with a noncompressible fluid; and a working member which is supported by the first mounting member such that the working member extends, in the fluid chamber, in a direction substantially perpendicular to a central axis of the tubular portion of the second mounting member, and thereby divides the fluid chamber into two divided chambers which are located on opposite sides of the working member, respectively, and which are communicated with each other via a fluid-flow restricting passage defined by at least the working member, the elastic rubber body including at least one thin portion which is located on a side of one of the two divided chambers and which is thinner than a remaining portion of the rubber body so as to be more easily elastically deformable than the remaining portion.
In the fluid-filled vibration damping device according to the first feature (1), the elastic rubber body includes at least one more easily elastically deformable thin portion which is located on the side of one of the two divided chambers which are communicated with each other by the fluid-flow restricting passage. Accordingly, when a vibrational load is input to the vibration damping device and the working member is reciprocatively or periodically moved in the fluid chamber, the thin portion is more easily elastically deformed to permit a relative change between respective volumes of the two divided chambers. That is, the fluid is permitted to flow in more amount through the restricting passage. Therefore, the present vibration damping device can exhibit a higher vibration damping effect based on the flows of the fluid through the restricting passage.
The fluid-flow restricting passage may be defined by, and between, respective opposed portions of an outer circumferential surface of the working member and an inner circumferential surface of the fluid chamber, or may additionally include at least one through-hole formed through the thickness of the working member. The shape or structure of the working member is by no means limited. For example, the working member may have a circular, an elliptical, or a polygonal outer periphery or contour.
Otherwise, an outer circumferential surface of the working member may be covered with an elastic rubber layer. The means or structure used for attaching the working member to the first mounting member is by no means limited. For example, the first mounting member may include an integral support axial portion which projects from the remaining portion of the first member into the fluid chamber, and the working member may be fixed by, e.g., caulking to a free end portion of the axial portion that projects in the fluid chamber. The shape of the elastic rubber body is by no means limited, and may be determined depending upon, e.g., vibration damping characteristics the vibration damping device is required to have. For example, the elastic rubber body may have a thick disc-like shape, and the tubular portion of the second mounting member may be fixed to an outer circumferential surface of the disc-like rubber body. Alternatively, the rubber body may have a frustoconical shape or a thick-walled tapered tubular shape that projects from the tubular portion of the second mounting member in an outward direction away from the open end of the tubular portion. In the latter ca
Kato Kazuhiko
Suzuki Tatsuya
Hurr & Brown
Oberleitner Robert J.
Tokai Rubber Industries Ltd.
Williams Thomas J.
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