Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1997-08-04
2001-09-25
Graham, Matthew C. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S152000
Reexamination Certificate
active
06293532
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to devices for controlling dynamic vibration. Specifically, it relates to elastomer and fluid containing apparatus for control of vibration between a member and structure.
BACKGROUND OF THE INVENTION
Fluid and elastomer apparatus, i.e., hydraulic mountings, isolators, and dampers include a fluid which augments the isolation and/or damping characteristics that may be achieved within elastomer mountings alone. This augmentation may take the form of adding additional tuned damping or tuned inertial effects. Fluid mountings are generally described in LORD® Technical Article LL-2166 entitled “Understanding Hydraulic Mounts for Improved Vehicle Noise, Vibration and Ride Qualities” by W. C. Flower. Commonly assigned U.S. Pat. No. 4,811,919 to Jones describes an inertial-type fluid mounting which incorporates a volume compensator.
Other examples of elastomer and fluid apparatus may be found in commonly assigned U.S. Pat. Nos. 5,540,549 and 5,501,434 to McGuire, 5,413,320 to Herbst, 5,374,039 to Schmidt et al., 5,197,692 to Jones et al., and 5,127,607 to McGuire. Fluid isolators, which are a subset of general fluid apparatus, are, in essence, tunable passive devices which use a fluid mass to create inertial forces which are used in conjunction with spring or elastic forces to tune the isolator dynamic characteristics relative to the frequency of vibratory input.
U.S. Pat. No. 4,236,607 to Halwes describes a vibration isolator having a tuning mass including a liquid which generates amplified counter-inertial forces. Notably, Halwes suffers from the problem that it cannot adequately compensate for temperature differentials which cause expansion of the fluid therein. Further, it may be difficult to obtain enough fluid mass in the straight-through inertia track design as described in Halwes. Further, there is a lack of tuneability in Halwes. Furthermore, the pockets formed in elastomer to receive lugs
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in Halwes may act as stress concentrators which may adversely effect rubber fatigue. Simply, it may be advantageous to have a larger surface area to reduce rubber stresses within the part. Optionally, it may be desirable to lower the length of the isolator.
SUMMARY OF THE INVENTION
Therefore, in light of the advantages and drawbacks of the prior art, the present invention is an apparatus, such as a fluid isolator, for attaching between a vibrating member and a structure. Preferably, the apparatus is an isolator which utilizes “tuned inertia” effects to cancel vibration. In one aspect of the invention, the fluid apparatus comprises an inner member, an outer member, and an elastomer element flexibly interconnecting them, a first operating chamber including a first moveable wall portion defined by the elastomer element, and a second operating chamber including a second moveable wall portion defined by an axially moveable piston. A passageway interconnects the first and second operating chambers, and a fluid contained therein oscillates in response to relative movements between the inner and outer members. A spring flexibly suspends the axially moveable piston such that dynamic motion between said inner and outer member displaces said piston and spring.
According to another preferable aspect, the inner member includes a hollow cavity which houses both the piston and spring. The piston is statically displaceable in response to temperature buildup within said isolator or dynamic perturbations due to relative movement of fluid between the operating chambers. In accordance with another aspect, the stiffness of said spring is changed to adjust a resonant parameter within said isolator. Optionally, the piston mass itself or an additional tuning mass mounted on the piston may be adjusted to accomplish tuning of a resonant parameter of the apparatus.
In a preferred embodiment, a rolling diaphragm is operative with said piston and dynamically displaceable in response to relative movement between said inner and outer members. In a space saving aspect, the passageway is an inertia track having a “tuned inertia” and includes a helical shape. The passageway assembly preferably seats against a peripheral seal formed on the rolling diaphragm to position and seal same. Alternatively, the piston may be suspended from an elastomer member or part of a metal bellows.
It is an advantage in one aspect of the present invention that a separate volume compensator is not required.
It is an advantage in one aspect of the present invention that a the effective tuned mass may be easily tuned without rebonding.
It is an advantage in one aspect of the present invention that a compact configuration may be obtained.
It is an advantage in another aspect of the present invention that a the effective volume stiffness of one of the chambers may be easily tuned without rebonding.
The above-mentioned and further aspects, advantages and characteristics of the present invention will become apparent from the accompanying descriptions of the preferred embodiments, claims, and attached drawings which follow.
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Flower, Wallace C.; Lord Corporation. “Understanding Hydraulic Mounts for Improved Vehicle Noise, Vibration and Ride Qualities”; May 15-17, 1985, LL 2166.
Lord Aerospace. “Fluidlastic Technology. Shock and Motion Control”; 1991, PB 6310.
Gnibus Michael M.
Graham Matthew C.
Lord Corporation
Wayland Randall S.
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