Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2002-09-27
2004-10-05
Graham, Matthew C. (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140110, C267S035000
Reexamination Certificate
active
06799753
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Applications No. 2001-303106 filed on Sep. 28, 2001, and No. 2002-027362 filed on Feb. 4, 2002, each including the specification, drawings and abstract, are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a fluid-filled elastic mount adapted to exhibit a vibration-damping effect on the basis of flows of a fluid filling a fluid chamber thereof, and more particularly to such a fluid-filled elastic mount that is novel in construction and that is suitably usable as an engine mount, a body mount or other mounts for use in automotive vehicles.
2. Description of the Related Art
A suspension-type fluid-filled elastic mount is known as one type of an elastic mount interposed between two members of a vibration system for flexibly connecting these two members in a vibration-damping or isolating fashion. As disclosed in JP-A-63-167142 and JP-A-4-334625, the known suspension-type fluid-filled elastic mount elastically supports a vibrative member, e.g., a power unit of an automotive vehicle, with respect to a subject member whose vibration is to be damped, e.g., a body of the vehicle, by suspending the vibrative member from the subject member.
FIG. 24
shows an example of the known suspension-type fluid-filled elastic mount, by way of example, in which a first mounting member
150
attachable to the power unit and a second mounting member
152
attachable to the body are elastically connected with each other by a tapered rubber elastic body
156
disposed between the first mounting member and a lower open-end portion of a vertically extending cylindrical portion
154
of the second mounting member
152
into which the first mounting member
150
is inserted so as to extend into the cylindrical portion
154
for fluid-tightly closing the lower open-end portion of the cylindrical portion
154
of the second mounting member
152
. An axially upper end portion of the cylindrical portion
154
of the second mounting member
152
is fluid-tightly closed by a flexible layer
158
, whereby a fluid chamber
160
is formed between and defined by the rubber elastic body
156
and the flexible layer
158
. A partition member
162
is disposed within the fluid chamber
160
so as to extend in a radial direction perpendicular to an axial direction of the cylindrical portion
154
of the second mounting member
152
, and is fixedly supported at its peripheral portion by the second mounting member
152
, so that the fluid chamber
160
is fluid-tightly divided by the partition member
162
into two sections, namely, a pressure-receiving chamber
164
partially defined by the rubber elastic body
156
and an equilibrium chamber
166
partially defined by the flexible layer
158
. The pressure-receiving chamber
164
and the equilibrium chamber
166
are held in fluid communication with each other through an orifice passage
168
.
With such a known suspension-type fluid-filled elastic mount installed in position, a static load or weight of the vibrative member, e.g, the power unit, is applied between the first mounting member
150
and the second mounting member
152
in the axial direction, and a vibrational load is primarily applied between the first and second mounting members
150
,
152
in the axial direction, as well. Thus, the known suspension-type fluid-filled elastic mount is tuned to be able to exhibit a damping effect based on resonance or flows of the fluid through the orifice passage
168
exclusively to vibrations applied thereto in the axial direction.
However, the known suspension-type fluid-filled elastic mount may possibly be subjected to vibrations applied thereto in the radial directions perpendicular to the axial direction, depending upon a state of installation thereof. If the suspension-type fluid-filled elastic mount is used as an engine mount for an automotive vehicle, for example, the engine mount may be subjected to vibrational loads applied between the first mounting member
150
and the second mounting member
152
in the radial directions, e.g., in a driving or a longitudinal direction of the vehicle and/or in a transverse direction of the vehicle, when the vehicle is accelerated, runs over steps, goes through corners, or experiences any other possible driving conditions. Actually, the known suspension-type fluid-filled elastic mount has not been sufficiently examined in its damping capability with respect to vibrations applied thereto in the radial directions.
In view of the above, the present inventors have conducted extensive studies and researches on damping characteristics of the known suspension-type fluid-filled elastic mount upon application of vibrations thereto in the radial directions, and it has been revealed that the known suspension-type fluid-filled elastic mount is incapable of exhibiting a desired damping effect with respect to vibrations applied thereto in the radial directions. Especially, the suspension-type elastic mount is prone to experience considerable deterioration of its damping capability at around a higher frequency range of input vibrations corresponding to an acceleration noise range of 300-500 Hz.
SUMMARY OF THE INVENTION
It is therefore one object of this invention to provide a suspension-type fluid-filled elastic mount novel in construction and capable of exhibiting an improved damping capability with respect to vibrations applied thereto in a radial direction perpendicular to its axial direction, without deteriorating its damping capability with respect to vibrations applied thereto in the axial direction and its manufacture efficiency due to increase in the number of components or the like.
In an attempt to solve the conventionally experienced problem, the present inventors have been conduced a further extensive study of the suspension-type fluid-filled elastic mount. In the suspension-type fluid-filled elastic mount, the elastic body has a generally frusto-conical shape, and is bonded at its central portion to the first mounting member and at its peripheral portion to the lower open-end portion of the cylindrical portion of the second mounting member, so that the central portion of the elastic body protrudes into an interior space of the cylindrical portion of the second mounting member by a relatively large distance, thereby effectively reducing or preventing occurrence of tensile stress in the elastic body when the elastic mount is installed in position and a static load, e.g., the weight of the power unit acts on the elastic body. When the suspension-type fluid-filled elastic mount constructed as described above is subjected to vibrations applied thereto in radial directions perpendicular to the axial direction, the central portion of the elastic body is forced to be moved back and force or displaced reciprocatively in the radial or diametric directions within the fluid chamber. As a result, an annular region defined by and between the central portion of the elastic body and the cylindrical portion of the second mounting member opposed to the central portion of the elastic body in the radial directions, experiences a volume variation in a circumferential direction thereof, thus causing flows of the fluid in the circumferential direction within the annular region. In view of the above, the present inventors have concluded that the suspension-type fluid-filled elastic mount may suffer from considerable increase in the spring constant based on resonance effect of the fluid flowing through the annular region, upon application of vibrations whose frequency range is higher than a resonance frequency of the fluid flowing through the annular region.
In the light of the above described conclusion, the present inventors have conducted still a further extensive study and research of the suspension-type fluid-filled elastic mount, and then have developed a suspension-type fluid-filled elastic mount according to the present invention. There will be described presently preferred modes of the
Hashimoto Fumiaki
Okanaka Takehiro
Beyer Weaver & Thomas LLP
Tokai Rubber Industries Ltd.
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