CA1297507C - Fluid filled vibration isolator having plural tunable dynamic stiffnesses - Google Patents
Fluid filled vibration isolator having plural tunable dynamic stiffnessesInfo
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- CA1297507C CA1297507C CA000535911A CA535911A CA1297507C CA 1297507 C CA1297507 C CA 1297507C CA 000535911 A CA000535911 A CA 000535911A CA 535911 A CA535911 A CA 535911A CA 1297507 C CA1297507 C CA 1297507C
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Abstract
FLUID FILLED VIBRATION ISOLATOR HAVING
PLURAL TUNABLE DYNAMIC STIFFNESSES
Richard P. Thorn Erie, Pennsylvania Abstract of the Disclosure A fluid filled vibration isolator having several dynamic stiffness levels at different amplitudes in a low frequency range is provided. The vibration isolator has opposed chambers in continuous fluid communication via an elongate main inertia track passageway and a main decoupler which cooperate with auxiliary inertias extending in fluid parallel relation with the main inertia passageway and in fluid series relation with the main decoupler to provide a low frequency small amplitude dynamic stiffness which is capable of being independently tuned relative to the low frequency large amplitude maximum dynamic damping stiffness.
PLURAL TUNABLE DYNAMIC STIFFNESSES
Richard P. Thorn Erie, Pennsylvania Abstract of the Disclosure A fluid filled vibration isolator having several dynamic stiffness levels at different amplitudes in a low frequency range is provided. The vibration isolator has opposed chambers in continuous fluid communication via an elongate main inertia track passageway and a main decoupler which cooperate with auxiliary inertias extending in fluid parallel relation with the main inertia passageway and in fluid series relation with the main decoupler to provide a low frequency small amplitude dynamic stiffness which is capable of being independently tuned relative to the low frequency large amplitude maximum dynamic damping stiffness.
Description
~Z97507 . ,.', .' FLUID ~ILLED VIBRATION ISOLATOR HAVING
PLURAL TUNABLE DYNAMIC STIFFNESSES
Richard P. Thorn Erie, Pennsylvania Field of the Invention The present invention relates to fluid filled vibration isolators, and more particularly, the present invention relates to fluid filled vibration isolator~ of the - type having inertia track pas~ageways and decouplers.
'.' Background of the Invention Fluid filled vibration isolators are being used to mount engines and transmission3 in modern automobiles. A
typical fluid filled vibration isolator includes a flexible wall hou~ing which is divided interiorly by a partition to form opposed chambers in fluid communication with one another via an elongate main inertia track passageway. In response to vibrations, fluid is alternately pressurized in the chamber~ and oscillate~ in the inertia track passageway.
In operation, this type vibration isolator provides a minimum dynamic stiffness, or notch in the dynamic ~tiffness curve, followed by a peak in the dynamic stiffness curve, at low excitation frequencies (about 10-15 Hertz) at large amplitudes (- about 1.0 mm.). Maximum dynamic damping stiffne~ typically occurs between the notch and the peak in I ~a~
the stiffness curve and is desirable to control engine bounce.
To render the inertia track passageway inactive during small amplitude dynamic excltations occurring over a broad frequency spectrum, i.e. up to about 200 Hertz, and at small amplitudes (less than about 0.1 mm.) the aforedescribed mounts preferably are provided with so-called decouplers.
When decouplers are combined with inertia track passageways, a small amplitude dynamic stiffne3s minimum, or notch in the stiffneqs curve, occurs at high frequencies,-i.e. about 150-200 Hertz. This dynamic operating characteristic is desirable to control engine firing di~turbances. Thus, a rluid filled vibration isolator having both an inertia track passageway and a decoupler has both of the aforementioned dynamic operating characteristics, i.e., a low frequency large amplitude mirimum dynamic stiffness and maximum dynamic damping stiffness, and a high frequency small amplitude minimum dynamic stiffnesQ.
Fluid filled vibration isolators of the aforedescribed inertia track and decoupler type can be tuned to a certain extent by incorporating any of various means ln the design of the isolator, ~uch as varying the length to effective diameter ratio of the inertia track passageway, varying the compliance of the chamber walls, varying decoupler design and cage configuration, etc. By utilizing one or more of these de~ign techniques, a designer can ad~ust the aforementioned dynamic operating characteristics to some extent to accommodate vibrations occurring in critical frequency regirns.
~ 1297507 There are certain applications in which it is de~irable for a fluid filled vibration isolator of the aforedescribed inertia track and decoupler type to be tuned so that it has one or more additional regions of relatively low dynamic stiffness followed by a peak in dynamic stiffness to accommodate vibrations occurring in one or more critical frequency ranges and amplitudes of vibration across the mount.
For instance, in certain automobiles, particularly those having four cylinder engines, it is desirable for a fluid filled vibration isolator to have a region of either minimum effective dynamic stiffness or maximum dynamic damping stiffness at small input amplitude-s in the low frequency range in order to accommodate certain noises generated or resonances excited by engine idle disturbanceq. Heretofore, however, it has been difficult to provide a fluid filled vibration isolator capable of accommodating simultaneously these dynamic operating requirements because of the limitation~ and incompatibility of known tuning techniques.
Objectq of the Invention With the foregoing in mind, it is a primary object of the present invention to provide, in a fluid filled vibration isolator having a main inertia track passageway and `~
a decoupler, a novel auxiliary inertia means cooperable to provide certain desirable independently tunable dynamic operating characteristicq.
Another object of the present invention is to provide an improved f1uid filled vibration iso1ator whicù has . 1 3 1297S~)7 ~. ' , ;.
desirable low frequency ~mall amplitude dynamic characteristics located in a region which is relatively close to a region of low frequency high amplitude maximum dynamic damping stiffness.
A further object of the present invention is to provide an improved fluid filled vibration isolator which has desirable dynamic stiffnesses at both low frequency large amplitude excitation inputs and high frequency small amplitude excitation inputs yet which can also be provided with either a small amplitude maximum dynamic damping stiffness or a minimum dynamic stiffness in a selected low frequency range close to the frequency of maximum large amplitude dynamic damping stiffness.
.. , , I
Summary of the Invention . .
More specifically, in the present invention, a fluid filled vibration isolator of the type having a pair of chambers in fluid communication with one another via an elongate main inertia track passageway and having a main decoupler is provided with auxiliary inertia means cooperable with the main inertia track passageway and the main decoupler to provide a desirable small amplitude dynamic stiffness capable of being located by design relatively close to the low frequency large amplitude maximum dynamic damping stiffness region. The auxiliary inertia means may be provided either by an auxiliary fluid slug dispo~ed in fluid parallel relation with the main inertia track passageway and in fluid series relation with the decoupler, or by a ~Z97507 similarly arranged non-fluid mass, each movable relative to the chambers in response to alternating relative pressurization thereof. In several embodiments, the auxiliary fluid slug i~ provided by one or more conduits which extend in opposite directions from the decoupler and which may have one or more auxiliary decouplers operatively associated therewith. In other embodiments, the main decoupler may have one or more conduits and chambers formed therein both to provide fluid slugs and to contain the auxiliary decouplers. The main decoupler may also carry non-fluid inertia means movable relative to the decoupler and to the chambers.
;, Brief Description of the Drawin~s The foregoing and other objects, features and ¦ advantages of the preqent invention should become apparent from the following description when taken in con~unction with the accompanying drawings, in which:
FIG. 1 is a transverse sectional view of a fluid filled vibration isolator embodying the present invention;
FIG. 2 is a sectional view taken on line 2-2 of FIG. 1;
FIG. 3 is an enlarged fragmentary sectional view of one modified embodiment of the present invention;
FIG. 4 is a plan view taken on line 4-4 of FIG. 3;
FIG. 5 is a view, similar to FIG. 3, but of another ¦ modified embodiment of the present invention;
FIG. 6 is a view, similar to FIGS. 3 and 5, but of a furthe modlfled embodiment of the present lnvention;
~,_ ~Z97S()7 FIG. 7 i~ an enlarged fragmentary sectional view of another modified embodiment of the present invention;
FIG. 8 is a plan view taken on lrregular line 8-8 of FIG. 7;
. FIG. 9 is a view, similar to FIG. 7, but of a further modified embodiment of the present inYention;
FIG. 10 is a view, similar to FIGS. 7 and 9, but of a still further modified embodiment of the pre~ent invention;
FIGS. 11A and 12A are typical curves plotting dynamic stiffness relative to frequency for a conventional fluid filled vibration isolator; ~
FIGS. 11B and 12B are curves similar to FIGS. 11A
and 12A but illustrating certain dynamic operating characteristics of a fluid filled vibration isolator embodying the present invention; and FIGS. 11C and 12C are curves similar to FIGS. 11B
and 12B but illustrating the effects on dynamic characteristics of changing certain dimenqional relations in the vibration isolator of the present invention.
Description of_the Preferred Embodiments Referring now to the drawings, FIG. 1 illustrates a fluid filled vibration isolator 10 which embodies the present invention. The vibration isolator 10 is adapted to be connected by suitable means, such as upper and lower mounting studs 12 and 13, respectively, to and between relatively movable structures, such an automobile engine and frame.
When mounted in a conventional manner, the upstanding stud 12 is connec~ed to the engine, and the depending ~tud 13 is connected to the frame. In some cases an inverted installation is preferred. As will be discuqsed, the vibration isolator 10 accommodates vibrations between the engine and frame in a particular novel manner.
. In the illustrated embodiment, the vibration isolator 10 includes a lower stamped metal cup 14 from which the mounting stud 13 dependq and an overlying upper cap assembly 15 from which the mounting stud 12 projects. The upper cap assembly 15 include~ a solid central metal core 15a to which the mounting qtud 12 is secured and which is movably connected to a shaped rigid tubular metal wall 15b by means of an annular frusto-conical flexible elastomeric wall 15c bonded to and extending between the central core 15a and the tubular wall 15c. The cap assembly 15 cooperates with the cup 14 to define therebetween a hollow cavity which is intended to be filled with fluid, but which is not shown filled for sake of clarity.
The fluid cavity iq horizontally divided internally by a partitlon 20 extending transversely with respect to the longitudinal path of movement of the mounting stud 12. The partition 20 divides the fluid cavity into an upper, or primary, Pluid chamber 21 above the partition 20, and a lower, or secondary, fluid chamber 22, below the partition 20.
The upper fluid chamber 21 is rendered fluid tight by virtue of the construction of the upper cap assembly 15. The lower fluid chamber 22 is rendered fluid tight by a flexible wall, or dlaphragm~ oi elastomerlc material 23 which i 9 disposed ~297SC~7 between the partition 20 and the vented bottom 14b of the cup 14.
For the purpose of developing a low frequency maximum dynamic damping stiffness at large amplitude input excitations, a main inertia track passageway 30 is provided.
As be~t seen in FIG. 2, the main inertia track passageway 30 is located alongside the partition 20 and has openings 30a, 30b at opposite ends providing fluid communication between the upper fluid chamber 21 and the lower fluid chamber 22, respectively. In the illustrated embodiment, the main inertia track passageway 30 is elongate and arcuate, and i9 formed in a plate 30c which is fastened to the partition 20, as by welding. As well known in the art, the main inertia track passageway 30 has a predetermined length to effective diameter ratio between openings 30a, 30b determined by variouq design considerations but which may, and preferably is, at least about 5:1 to about 30:1. The main inertia track passageway 30 cooperateq with fluid contained in the chambers 21 and 22 upon alternating relative pressurization of the fluid therein to cause fluid to oscillate in the main inertia track passageway 30 and thereby provide a desirable damping action under relatively large amplitude low frequency input excitations.
To decouple, i.e. to render substantially inactive, the inertia track passageway 30 for low frequency small amplitude input excitationq, main decoupler means is provided.
In the embodiment illustrated in FIG. 1, the main decoupler means Lncludes a circular disc-type decoupler element 31 ~2975~37 mounted in a cage 32 below the partition 20. The cage 32 surrounds the decoupler disc 31 below the underside of the partition 20 and determines both the vertical limits of translation of the disc 31 and its peripheral clearance, the magnitudes of both of which are quite small and determined by factors known to those skilled in the art.
For the purpose of causing the main decoupler disc 31 to oscillate in its cage 32 in response to relative alternate pressurization of fluid in the chambers 21, 22, opposite sides 31a, 31b of the decoupler disc 31 are exposed to the upper and lower fluid chambers 21, 22 respectively via upper and lower ports 33a, 33b, respectively. In the illustrated embodiment, the upper port 33a is formed in the partition 20, and the lower port 33b is formed in the decoupler cage 32. The main decoupler disc 31 cooperates with the main inertia track passageway 30 to provide in the vibration isolator 10, both the aforementioned low frequency maximum dynamic damping stiffness at large excitation input amplitudes and high frequency minimum dynamic stiffness at small excitation input amplitudes, as well known in the art.
For instance, a vibration isolator of this general type exhibits the typical dynamic operating characteristics illustrated in FIGS. llA and 12A, having a low frequency ,~
maximum dynamic damping stiffness at about 12-14 Hz., and a high frequency minimum dynamic s-tiffness at a much higher frequency, i.e., above about 150 Hertz (not shown).
A more detailed discussion of the theory of opera-tion of fluid filled fibration isolators may be found in an article entitled "A New Generation of Engine Mounts", by Marc Bernuchon, SAE Technical Paper Series 840259, 1984.
To limit upward motion of the cap assembly 15 relative to the cup 14 in the unloaded assembled condition illustrated, snubber means is provided. To this end, a convex retainer plate 25 extends transversely across the upper portion of the upper fluid chamber 21. The retainer plate 25 has a central aperture 25a which receives an elas-tomeric annular snubber 27 that is internally reinforced by a plate 28 and fastened to the bottom of the central core 18 by the head of the mounting stud 12. The snubber 27 engages the underside of the retainer plate 25 around its aperture 25a to limit the upward displacement of the cap 15 both in a static unloaded condition as assembled and illus-trated, and in a dynamic condition, as when the engine movesaway from the frame.
To enable the vibration isolator 10 to be assembled readily, the decoupler cage 32 is captured in a recess formed in the plate 30c in which the main passageway 30 is stamped.
In addition, the partition 20, retainer plate 25, lower flexible chamber wall 23, and spacers, are received about their peripheries in an annular recess provided between an -~v -- 10 --h lZ~7SU~ I
inturned flange 15' on the cap wall 15b and an outturned flange 14' of the cup 14. The cap flange 15' is crimped about the periphery of the cup flange 14' to complete the assembly and to render it fluid tight. Th~q may also be made as an integral drawn extension of the plate 30c.
. In the conventional fluid filled vibration isolator the ports between the decoupler disc and fluid chambers, such as the ports 33a, 33b, generally have a large cross-sectional areas and short lengths. For instance, the area of either port may be, and preferably is, at least about 80 percent of - the transverse cross-sectional area of the decoupler disc.
The length of the port is determined by the thickness of the structure in which it is formed, and usually this is about the thickness of the partition 20. Accordingly, with conventional fluid filled vibration isolators having decouplers, the lengths of the ports between the fluid chambers and the decoupler is quite short relative to its diameter, or cross-sectional area. This produces dynamic operating characteri~tics such as discussed above and such as illustrated in FIGS. 11A and 12A in the low frequency regime.
In accordance with the present invention, it has been determined that certain highly desirable dynamic effects can be achieved by incorporating within a fluid filled vibration isolator of the aforedescribed type, auxiliary inertia means having a predetermined inertia, which is less than the inertia of the fluid in the main inertia track passageway, yet which is movable relative to the chambers in response to relative alternate pressurization of fluid i ~Z97507 therein. The auxiliary inertia means cooperates with the fluid in the main inertia track passageway and with the decoupler to provide a ~elecked level of dynamic stiffnes~, or damping, at a predetermined input excitation frequency and am?litude. As will be diqcus~ed, the frequency range and the amplitude ~ensitivity of a vibration isolator incorporating the present invention can be tuned substantially independently of the dynamic operating characteristics resulting from the interaction of the main inertia track passageway and main decoupler.
In the embodiment illustrated in FIG. 1, the aforedescribed effects are Drovided by a pair of conduits 40a, 40b extending in opposite directions from opposite sides of the decoupler 31 to define a like pair of fluid slugs S1, S2. In the illustrated embodiment, the upper conduit 40a is formed integral with the partition 20 and confronts the upper surface 31a of the decoupler disc 31 via the port 33a. The lower conduit 40b extends into the lower chamber 22a from the lower surface 31b of the decoupler disc 31 and is in fluid communication therewith via the port 33b. Preferably the lower conduit 40b is formed integral with the decoupler cage 32, and has a series of peripheral notches 40' in its lower edge for permitting fluid flow in the event the lower flexible wall 23 engages the lower end of the conduit 40b in the course of operation of the vibration isolator 10.
In the embodiment of FIG. 1, both the upper conduit 40a and the lower conduit 40b are of the same length and cross-sectional area, which is preferably circular, such as illustrated In FIG. Z, and the conduits 40a, 40b are flaired 1 ~
~ ~Z975(37 in the zone of the port~ 33a, 33b adjacent the decoupler di~c 31. The fluid slug S1 defined by the upper conduit 40a extends between the topside 31a of the decoupler disc 31 and the upper chamber 21, and the fluid slug S2 defined by the lower conduit 40b extends between the underside 31b of the decoupler disc 31 and the lower fluid chamber 22. Thus, for purpo~es of explanation, the fluid slu~s S1 and S2 can be regarded as extending in fluid parallel relation with the fluid contained in the main inertia track passageway and in fluid serie~ relation with the decoupler disc 31. The combined inertias of the fluid slugs S1, S2 is less than that of the inertia of the fluid slug in the main inertia track passageway, preferably being less than about 50 percent thereof. This conduit configuration provides balanced flow conditions on opposite side~ of the decoupler disc 31 and is, therefore, highly desirable.
In operation, the vibration isolator 10 retains the conventional low frequency large amplitude and high frequency small amplitude dynamic operating characteristics discussed above. In addition, however, it exhibits an additional low frequency small ~mplitude minimum dynamic ~tiffness followed by peak damping stiffness characteristic, which is capable of ¦ being tuned independently of the large amplitude low j frequency maximum dam~ing stiffness. In the embodiment of FIG. 1, the low frequency small amplitude maximum dynamic I damping stiffness is located relatively close to the low frequency large amplitude maximum dynamic damping stiffness.
The dynamic operating characteristics of the vibratio isolator 10 may est be ob served by re f ere nce to l lZ97S07 FIGS. 11B and 12B wherein dynamic stiffne~s is plotted relative to frequency for a vibration isolator constructed in accordance with the teaching~ of the present invention. The dot-dash curve, representing the low frequency large amplitude dynamic operating conditions, is of conventional shape and exhibits a maximum dynamic damping stiffness at a relatively low frequency for a + 1.0 mm. input excitation amplitude. These curve~ compare favorably with the corresponding curves in FIGS. 1lA and 12A for the same + 1.0 mm. amplitude. However, in the low frequency range, for ~mall amplitude input excitations as indicated by the 0.25 and 0.1 millimeter curves in FIGS. 11B and 12B, the present invention provides dynamic damping stiffness maximums which are located close to the large amplitude dynamic damping stiffne~s maximums, i.e. at about 25 to 30 Hz. for idle absorption. These curves are to be compared with the corresponding curves in FIGS. 1lA and 12A, wherein for small I s amplitude input excitations, the curves are relatively flat in the low frequency range indicating low stiffness and insignificant damping.
The locations and magnitudes of the small amplitude high frequency minimum dynamic stiPfnesses are essentially unaffected by the ~tructure of the present invention. Thus, they have been omitted from the curves in FIGS. 11A-12C.
The length to diameter ratio of the conduits 40a, 40b relative to the maln Inertia track passageway 30 ~ :
I
~ I
l!
determines the magnitudes of the masses of the fluid slugs S1, S2 and thus determines dynamic operating characteristics of the vibration isolator 10. In the embodiment illustrated in FIG. 1, each conduit, quch as the upper conduit 40a, has a predetermined length to diameter ratio which is smaller than the correQponding ratio of the main inertia track passageway 30 and provides a smaller fluid inertia. For example, both conduits 40a and 40b combined have a length to diameter ratio, and hence effective inertia, which is in a range of about 15 to about 20 DerCent of the corresponding length to diameter ratio, and hence fluid inertia, of the main inertia track passageway 30 between its end openings 30a, 30b.
The dynamic operating characteristics of the isolator 10 may be varied to some extent by varying the length to diameter ratio of either, or both, of the conduits 40a, 40b to tune the isolator 10. By way of example, a doubling of the diameter of each conduit 40a, 40b, while maintaining their lengths constant, causes the low frequency small amplitude maximum dynamic damping stiffness to be shifted to slightly higher frequency levels without significantly affecting the low frequency large amplitude maximum dynamic damping stiffness level and frequency. Such shifting may be observed by comparing FIGS. 11C and 12C, corresponding to an isolator having a doubled cross-sectional conduit area, with the corresponding curves llB and 11C
corresponding to the conduit size relations discussed above.
If desired, one or the other of the conduits 40a, 40b may be omitted and some teneficial efrects retained, although it has been determined that a fluid filled vibration iqolator having only a single conduit exhiblts leqs well defined dynamic operating characteristics than those illustrated in FIGS. 11B-12C.
In the illustrated embodiments, both conduits 40a, 40b are ri8id and are dimensioned so as not normally to be engaged by either the snubber 27 or the diaphragm 23 in the normal course of operation of the vibration isolator 10. In certain applications, however, it may be desirable for the lengths of the conduits 40a, 40b to be increased. In such event, the conduit~ 40a, 40b may be fabricated of a flexible tubular elastomeric material which is readily displaceable in response to engagement by either the snubber 27 or diaphragm 23 and which, therefore, i9 capable of being moved aside in response to extreme excursions of the snubber 27 or the diaphragm 23 in response to unusual loadir.g or operating conditions. Such elastomeric tubes may be molded of various shape~, such as the shape of the decoupler cage 32, and clamped in place in a similar manner to provide both the upper and lower conduits.
The embodiment illustrated in FIG. 1 is designed to provide a single additional region of maximum dynamic damping stiffness at small input excitation amplitudes in the low frequency range. If it is desired to provide several regions of maximum dynamic damping stiffness in that range for small amplitude input excitations, modified embodiments of the present invention are provided. In these modified embodiments~ a plurality of ~xiliary inertia mean5 are I lZ~7S07 providcd in fluid series relation with the main decoupler and in fluid parallel relation with the main inertia track passageway, and decoupler means are provided for selectively controlling fluid flow therein.
In a first modified embodiment illustrated in ~IGS. 3 and 4, the decoupler assembly includes identical upper and lower shells 50, 51 confined between the partition 20 and inertia track plate 30c in the manner illustrated.
Each ~hell, such as the upper shell 50, has a central elongate upper conduit portion 50a which is surrounded by an array of outer upper conduit portions 50b-50e. See FIG. 4.
In like manner, the lower shell 51 has a similar arrangement of conduits 51b-51d arranged in like manner about the lower central conduit 51a. The shells 50 and 51 are configured in the manner illustrated in FIG. 3 to provide therebetween a decoupler cage 53 which, in the present instance, has a short cylindrical shape. An annular decoupler 54 is mounted in the cage 53 and is interposed between the upper and lower sections of the outer array of conduits 50b-50e and 51b-51e.
In like manner, a circular decoupler disc 55 is mounted centrally of the annular decoupler 54 between the upper and lower central conduit sections 50a and 51a. In the illustrated embodiment, the height, or thickness, of the decoupler cage 53 is constant and is selected relative to the thickness of the annular decoupler 54 to limit the extent of its translatory movement in the vertical direction. The central decoupler disc 55 is thinner than the annular decoupler 5~ and, therefore, ~ves through a greater dist-nce relative to the decoupler cage 53 and relative to the annular decoupler 54~ Thus, a means is provided for limiting the extent of translation of each of the decouplers 54 and 55 with respect to its associated conduits.
With this structure, the central conduits 50a, 51a and the decoupler disc 55 have a predetermined length to diameter ratio and function much like the conduits and decoupler in the embodiment of FIG. 1 to provide the aforedescribed dynamic operating characteristics of the present invention. In addition, however, in this embodiment the array of upper and lower outer conduits 50b-50e, 51b-51e, surrounding the central upper and lower conduits provide an additional fluid passageway providing an effective fluid ~lug which has an inertia that is smaller than provided by the main passageway 30 but larger than provided by the central conduits 50a, 51a. Since the magnitude of translation of the annular decoupler 54 i9 less than that of the circular decoupler disc 55, the annular decoupler 54 blocks flow through the outer conduits at smaller input excitation amplitudes than the inner decoup]er disc 55 associated with the central conduit. A~ a result, in this embodiment, essentially two different auxiliary fluid masses may be active, or inactive, depending on input excitation amplitude.
For instance, at small input excitations, both decouplers 54 and 55 simply oscillate in the cage 53. As the input excitations increase in amplitude, the annular decoupler 54 blocks flow in the outer array of conduits 50b-50e, 51b-51e, while permitting flow to continue in the central conduits 50a, 51a. However, as the amplitude increases further, the central decoupler disc 55 blocks flow through the central conduits so that all flow through the auxiliary decoupler conduitq iq arrested and the main inertia pasqageway 30 is coupled. Thus, in this embodiment multiple regions of desirable dynamic stiffness characteristics, such as discussed above, may be provided at different relatively low frequency locations and at different relatively small input amplitudes. While in the embodiment of FIG. 3, the outer conduits are of the same size and length, it should be apparent that depending upon the dynamic effects desired, either the number of conduits, thèir lengths, and~or their shapes may be varied to achieve desired tuning effects as - discussed heretofore.
:~ Rather than utilizing the thickness of the decoupler cage relative to the decoupler disc to limit the extent of translation of the central decoupler disc in FIG. 3, the annular decoupler element 54 itself may be provided with decoupler motion limiting means~ To this end, as best seen in FIG. 5, a modified embodiment is provided which is similar to the embodiment of FIG. 3, but wherein the annular decoupler element 54 has an inner peripheral recess 54a which receive~ an outwardly projecting flange 55a of a central decoupler disc 55. The height or axial thicknes~s of the reces~ 54a in the annular decoupler element 54 determines the extent of translatory movement of the inner decoupler disc 55. The central portion of the inner decoupler disc 55 is thinner than the annular decoupler element 54 but thicker than the annular flange 55a. As a result, the inner section ~ lza7su7 can both translate and flex rel~t~ve to the annular element 54 and thereby bottom against confronting conduit seat~ 50~, 51'. The function of the embodiment in FIG. 5 is similar to that of the embodiment of FIG. 3 but provides better motion control of the central element and more positive sealing.
FIG. 6 illustrates a further modification of the present invention wherein a single flexible decoupler disc 56 is mounted in the cage 53 between the upper and lower shells 50 and 51. In this embodiment, however, a continuous decoupler disc 56 is molded of elastomeric material and has a relatively thin flexible circular central portion 56a confronting the central conduits 50a, 51a and has an enlarged outer peripheral bead portion 56b located ad~acent the inner peripher~ of the cage 53. The decoupler disc 56 also has a plurality of protrusions 56c, 56d which are located on oppo~ite sides thereof and which are aligned with the upper and lower conduit sections, such as the conduits 50b, 51b, 50d, 51d, respectively. With thi~ structure, the decoupler disc 56 oscillates in a planar manner in the cage 53 in respon~e to sma]l amplitude input excitations to block flo~
through the outer array of conduits. However, as the m~gnitude of input excitations increases, the decoupler disc 56 balloons centrally due to its reduced thickness in its central region 56a. This enables the protrusions 55c, 56d more positively to block flow through their associated conduits and the ali~ned central portion 56a of the decouoler disc 56 to block flow through the central conduit sections 50a, 51a. The embodiment Or FIG. 6 funotlons In much the ~0 12975~7 same manner as the embodiments of FIGS. 3~5, but with a simpler and quieter structure.
In the preceding embodimentq, the main decoupler is constrained for translation in a cage, and the auxiliary inertia means are provided by one or more fluid columns or slugs extending in opposite directions from the cage. If desired, however, other means may be provided for mounting the main decoupler, and the auxiliary inertia means may be provided by non-fluid masses. To this end, the embodiments of FIGS. 7-10 are provided.
Referring now to FIG. 7, the vibration isolator illustrated in fragmentary cross-section is like in construction to the isolator 10 but has a central circular bore 20a in its partition 20. A main, or high frequency, decoupler element 60 is mounted in the bore 20a for translation between the upper and lower fluid chambers 21 and 22. As best seen in FIG. 8, the decoupler 60 has a ~ spool-like configuration with vertically spaced upper and - lower peripheral flange~ 60a, 60b extending radially outward from its cylindrical body portion 60c which is slidably received in the bore 20a with a clearance therebetween providing a fluid flow passage. The outer peripheries of the flanges 60a, 60b have bulbous shapes and confront upper and lower marginal surfaces of the partition 20 around the bore 20a. The axial spacing between the flanges 60a, 60b, and the thickness of the partition 20 around the bore 20a determines the extent of the vertical movement of the decoupler 60.
j Preferabl the amount o~ the vertioal mo~ement i~ limited to l 21 ~ 1297507 a small magnitude consi~tent with the amplitudes of expected higher frequency motion across the mounting. Typically this total motion is less than about 1.0 mm.
In this embodiment, upper and lower fluid conduit portions 61a, 61b, respectively, are provided centrally within the higher frequency decoupler 60 and open into an enlarged auxiliary, cr lower frequency, decoupler cage 62 located centrally within the main decoupler 60. A circular auxiliary decoupler disc 63 is mounted in the decoupler cage 62 for vertical translation between opposed confronting annular seating surfaces 62a, 62b of the decoupler cage 62.
The spacing between the seating surfaces 62a, 62b is greater than the motion clearance for the main decoupler 60 and determines the limits of translation of the auxiliary decoupler 63 in its cage 62 consistent with the lower frequency vibration levels. In the present invention, the limits of movement of the auxiliary decoupler disc 63 are greater than the limits of translatory movement of the main decoupler 60, and both can be adjusted to meet specific vibratory levels at the respective fluid inertia resonances.
In operation, small amplitude input excitations cause both the main and auxiliary decouplers to oscillate, producing a relatively high frequency fluid resonance. As the amplitude of the input excitations increases, however, the main decoupler 60 blocks flow through the bore 20a while the auxiliary decoupler 63 continues to oscillate, producing a lower frequency fluid resonance. Further increases in input excitation amplitudes cause the auxiliary decoupler 63 to bottom and thereby block flow through the conduits 61a, ~ 12975a~7 61b causing the main inertia track to become active. A~ a result, in this embodiment, the dynamic effect produced i3 similar to that provided by the embodiments of FIGS. 3-6.
Preferably, the auxiliary decoupler disc 63 is of a material having a den~ity corresponding to the density of the working fluid contained within the fluid chambers 21, 22. If desired, however, the dynamic operating characteristics of the vibration isolator can be varied by utilizing materials of different densities relative to the working fluid. Since the main decoupler 60 is preferably molded of elastomeric material, it can stretch, so that the auxiliary decoupler 63 can simply be pushed into the decoupler cage 62 through either of the conduits 61a or 61b.
In the embodiment of FIG. 7, opposed fluid slugs in the conduits 61a, 61b and the swept volume of decoupler body 60 provide the required auxiliary inertia mean~. If desired, however, embodiments may be provided having non-fluid inertia mean~. To this end, a main decoupler 65, FIG. 9, having an outer configuration ~imilar to the decoupler 60, is mounted for tran~lation in a bore 20a in a partition 20. The decoupler 65 has a central through bore 65' providing fluid communication between the upper fluid chamber 21 and the lower fluid chamber 22. A non_fluid mass, such as a cylindrical pin 66, is slidably received in the bore 65' and i~ sized relative thereto to provide a fluid flow clearance therebetween. Opposite ends of the pin 66 are provided with enlarged heads 67, 68 each having annular surfaces 67a, 68a, 12975(,~7 respectively, confronting upper and lower annular surfaces 65a, 65b on opposite sides of the main decoupler 65 around its bore 65'. Preferably, the pin heads 67, 68 have convex : end surfaces 67', 68', as illustrated, and the pin 66 is molded of a material having a density corresponding to the . . density of the working fluid in the fluid chambers 21, 22.
. In this embodiment, the limits of translation of : the auxiliary decoupler 66 relative to the main decoupler 65 are determined by the axial spacing between the pin head surfaces 67a, 68a and their respective main decoupler surfaces 65a, 65b. Such spacings are greater than the qpacing between the upper and lower flanges of the main decoupler 65 relative to the thickness of the partition 20.
As a result, the pin heads 67, 68 close off fluid flow in the main decoupler bore 65' at relatively large input excitation amplitudes while the main decoupler flanges close off fiuid flow in the main decoupler bore 20a at smaller input ............... excitation amplitudes. It should be apparent, therefore, . that the embodiment of FIG. 9 functions in much the same manner as the embodiment of FIC. 7 to provide desired dynamic . operating characteristics.
In the embodiment of FIG. 9, the auxiliary decoupler 66 is preferably molded of plastic or like materials, but may be of a denser material, such as metal depending on the inertia desired. The pin heads 67 and 68 are sized and shaped so as to be capable of being inserted axially through the bore 65', the inherent elasticity of the main decoupler 65 per=itting it t~ stretch during such I ~4 1 ~2975~7 assembly. If desired, the pin 66 may be made in two pieces for easy a~sembly. Should it be desired to augment further the inertia of the auxiliary decoupler 66, an embodiment, such as illustrated in FIG. 10, may be provided wherein opposed pin heads 69 and 70 may be formed around very high den~ity masses, such a~ lead di~cs, 71, 72. Other than for these differences, the structure and function of the embodiment of FIG. 10 is essentially the same as the embodiment of FIG. 9.
In view of the foregoing, it should be apparent that the present invention now provides an improved fluid filled vibration i olator which is designed to provide plural regions of desirable dynamic stiffness levels at predetermined frequency and amplitude locations, such as at low frequency small amplitude input excitations. This is accomplished utilizing relatively simple, yet rugged, structures capable of being manufactured efficiently by high speed mass production techniques. Moreover, the desired dynamic operating characteristics can be obtained without sacrificing to a significant extent the conventional dynamic operating characteristics of a fluid filled vibration isolator of the type having an inertia track passageway and decoupler.
While preferred embodiments of the present invention have been described in detail, various modifications, alteratLon~ and changes may be made without departing from the spirit and scope of the present invention as defln d in the appended claims.
~5
PLURAL TUNABLE DYNAMIC STIFFNESSES
Richard P. Thorn Erie, Pennsylvania Field of the Invention The present invention relates to fluid filled vibration isolators, and more particularly, the present invention relates to fluid filled vibration isolator~ of the - type having inertia track pas~ageways and decouplers.
'.' Background of the Invention Fluid filled vibration isolators are being used to mount engines and transmission3 in modern automobiles. A
typical fluid filled vibration isolator includes a flexible wall hou~ing which is divided interiorly by a partition to form opposed chambers in fluid communication with one another via an elongate main inertia track passageway. In response to vibrations, fluid is alternately pressurized in the chamber~ and oscillate~ in the inertia track passageway.
In operation, this type vibration isolator provides a minimum dynamic stiffness, or notch in the dynamic ~tiffness curve, followed by a peak in the dynamic stiffness curve, at low excitation frequencies (about 10-15 Hertz) at large amplitudes (- about 1.0 mm.). Maximum dynamic damping stiffne~ typically occurs between the notch and the peak in I ~a~
the stiffness curve and is desirable to control engine bounce.
To render the inertia track passageway inactive during small amplitude dynamic excltations occurring over a broad frequency spectrum, i.e. up to about 200 Hertz, and at small amplitudes (less than about 0.1 mm.) the aforedescribed mounts preferably are provided with so-called decouplers.
When decouplers are combined with inertia track passageways, a small amplitude dynamic stiffne3s minimum, or notch in the stiffneqs curve, occurs at high frequencies,-i.e. about 150-200 Hertz. This dynamic operating characteristic is desirable to control engine firing di~turbances. Thus, a rluid filled vibration isolator having both an inertia track passageway and a decoupler has both of the aforementioned dynamic operating characteristics, i.e., a low frequency large amplitude mirimum dynamic stiffness and maximum dynamic damping stiffness, and a high frequency small amplitude minimum dynamic stiffnesQ.
Fluid filled vibration isolators of the aforedescribed inertia track and decoupler type can be tuned to a certain extent by incorporating any of various means ln the design of the isolator, ~uch as varying the length to effective diameter ratio of the inertia track passageway, varying the compliance of the chamber walls, varying decoupler design and cage configuration, etc. By utilizing one or more of these de~ign techniques, a designer can ad~ust the aforementioned dynamic operating characteristics to some extent to accommodate vibrations occurring in critical frequency regirns.
~ 1297507 There are certain applications in which it is de~irable for a fluid filled vibration isolator of the aforedescribed inertia track and decoupler type to be tuned so that it has one or more additional regions of relatively low dynamic stiffness followed by a peak in dynamic stiffness to accommodate vibrations occurring in one or more critical frequency ranges and amplitudes of vibration across the mount.
For instance, in certain automobiles, particularly those having four cylinder engines, it is desirable for a fluid filled vibration isolator to have a region of either minimum effective dynamic stiffness or maximum dynamic damping stiffness at small input amplitude-s in the low frequency range in order to accommodate certain noises generated or resonances excited by engine idle disturbanceq. Heretofore, however, it has been difficult to provide a fluid filled vibration isolator capable of accommodating simultaneously these dynamic operating requirements because of the limitation~ and incompatibility of known tuning techniques.
Objectq of the Invention With the foregoing in mind, it is a primary object of the present invention to provide, in a fluid filled vibration isolator having a main inertia track passageway and `~
a decoupler, a novel auxiliary inertia means cooperable to provide certain desirable independently tunable dynamic operating characteristicq.
Another object of the present invention is to provide an improved f1uid filled vibration iso1ator whicù has . 1 3 1297S~)7 ~. ' , ;.
desirable low frequency ~mall amplitude dynamic characteristics located in a region which is relatively close to a region of low frequency high amplitude maximum dynamic damping stiffness.
A further object of the present invention is to provide an improved fluid filled vibration isolator which has desirable dynamic stiffnesses at both low frequency large amplitude excitation inputs and high frequency small amplitude excitation inputs yet which can also be provided with either a small amplitude maximum dynamic damping stiffness or a minimum dynamic stiffness in a selected low frequency range close to the frequency of maximum large amplitude dynamic damping stiffness.
.. , , I
Summary of the Invention . .
More specifically, in the present invention, a fluid filled vibration isolator of the type having a pair of chambers in fluid communication with one another via an elongate main inertia track passageway and having a main decoupler is provided with auxiliary inertia means cooperable with the main inertia track passageway and the main decoupler to provide a desirable small amplitude dynamic stiffness capable of being located by design relatively close to the low frequency large amplitude maximum dynamic damping stiffness region. The auxiliary inertia means may be provided either by an auxiliary fluid slug dispo~ed in fluid parallel relation with the main inertia track passageway and in fluid series relation with the decoupler, or by a ~Z97507 similarly arranged non-fluid mass, each movable relative to the chambers in response to alternating relative pressurization thereof. In several embodiments, the auxiliary fluid slug i~ provided by one or more conduits which extend in opposite directions from the decoupler and which may have one or more auxiliary decouplers operatively associated therewith. In other embodiments, the main decoupler may have one or more conduits and chambers formed therein both to provide fluid slugs and to contain the auxiliary decouplers. The main decoupler may also carry non-fluid inertia means movable relative to the decoupler and to the chambers.
;, Brief Description of the Drawin~s The foregoing and other objects, features and ¦ advantages of the preqent invention should become apparent from the following description when taken in con~unction with the accompanying drawings, in which:
FIG. 1 is a transverse sectional view of a fluid filled vibration isolator embodying the present invention;
FIG. 2 is a sectional view taken on line 2-2 of FIG. 1;
FIG. 3 is an enlarged fragmentary sectional view of one modified embodiment of the present invention;
FIG. 4 is a plan view taken on line 4-4 of FIG. 3;
FIG. 5 is a view, similar to FIG. 3, but of another ¦ modified embodiment of the present invention;
FIG. 6 is a view, similar to FIGS. 3 and 5, but of a furthe modlfled embodiment of the present lnvention;
~,_ ~Z97S()7 FIG. 7 i~ an enlarged fragmentary sectional view of another modified embodiment of the present invention;
FIG. 8 is a plan view taken on lrregular line 8-8 of FIG. 7;
. FIG. 9 is a view, similar to FIG. 7, but of a further modified embodiment of the present inYention;
FIG. 10 is a view, similar to FIGS. 7 and 9, but of a still further modified embodiment of the pre~ent invention;
FIGS. 11A and 12A are typical curves plotting dynamic stiffness relative to frequency for a conventional fluid filled vibration isolator; ~
FIGS. 11B and 12B are curves similar to FIGS. 11A
and 12A but illustrating certain dynamic operating characteristics of a fluid filled vibration isolator embodying the present invention; and FIGS. 11C and 12C are curves similar to FIGS. 11B
and 12B but illustrating the effects on dynamic characteristics of changing certain dimenqional relations in the vibration isolator of the present invention.
Description of_the Preferred Embodiments Referring now to the drawings, FIG. 1 illustrates a fluid filled vibration isolator 10 which embodies the present invention. The vibration isolator 10 is adapted to be connected by suitable means, such as upper and lower mounting studs 12 and 13, respectively, to and between relatively movable structures, such an automobile engine and frame.
When mounted in a conventional manner, the upstanding stud 12 is connec~ed to the engine, and the depending ~tud 13 is connected to the frame. In some cases an inverted installation is preferred. As will be discuqsed, the vibration isolator 10 accommodates vibrations between the engine and frame in a particular novel manner.
. In the illustrated embodiment, the vibration isolator 10 includes a lower stamped metal cup 14 from which the mounting stud 13 dependq and an overlying upper cap assembly 15 from which the mounting stud 12 projects. The upper cap assembly 15 include~ a solid central metal core 15a to which the mounting qtud 12 is secured and which is movably connected to a shaped rigid tubular metal wall 15b by means of an annular frusto-conical flexible elastomeric wall 15c bonded to and extending between the central core 15a and the tubular wall 15c. The cap assembly 15 cooperates with the cup 14 to define therebetween a hollow cavity which is intended to be filled with fluid, but which is not shown filled for sake of clarity.
The fluid cavity iq horizontally divided internally by a partitlon 20 extending transversely with respect to the longitudinal path of movement of the mounting stud 12. The partition 20 divides the fluid cavity into an upper, or primary, Pluid chamber 21 above the partition 20, and a lower, or secondary, fluid chamber 22, below the partition 20.
The upper fluid chamber 21 is rendered fluid tight by virtue of the construction of the upper cap assembly 15. The lower fluid chamber 22 is rendered fluid tight by a flexible wall, or dlaphragm~ oi elastomerlc material 23 which i 9 disposed ~297SC~7 between the partition 20 and the vented bottom 14b of the cup 14.
For the purpose of developing a low frequency maximum dynamic damping stiffness at large amplitude input excitations, a main inertia track passageway 30 is provided.
As be~t seen in FIG. 2, the main inertia track passageway 30 is located alongside the partition 20 and has openings 30a, 30b at opposite ends providing fluid communication between the upper fluid chamber 21 and the lower fluid chamber 22, respectively. In the illustrated embodiment, the main inertia track passageway 30 is elongate and arcuate, and i9 formed in a plate 30c which is fastened to the partition 20, as by welding. As well known in the art, the main inertia track passageway 30 has a predetermined length to effective diameter ratio between openings 30a, 30b determined by variouq design considerations but which may, and preferably is, at least about 5:1 to about 30:1. The main inertia track passageway 30 cooperateq with fluid contained in the chambers 21 and 22 upon alternating relative pressurization of the fluid therein to cause fluid to oscillate in the main inertia track passageway 30 and thereby provide a desirable damping action under relatively large amplitude low frequency input excitations.
To decouple, i.e. to render substantially inactive, the inertia track passageway 30 for low frequency small amplitude input excitationq, main decoupler means is provided.
In the embodiment illustrated in FIG. 1, the main decoupler means Lncludes a circular disc-type decoupler element 31 ~2975~37 mounted in a cage 32 below the partition 20. The cage 32 surrounds the decoupler disc 31 below the underside of the partition 20 and determines both the vertical limits of translation of the disc 31 and its peripheral clearance, the magnitudes of both of which are quite small and determined by factors known to those skilled in the art.
For the purpose of causing the main decoupler disc 31 to oscillate in its cage 32 in response to relative alternate pressurization of fluid in the chambers 21, 22, opposite sides 31a, 31b of the decoupler disc 31 are exposed to the upper and lower fluid chambers 21, 22 respectively via upper and lower ports 33a, 33b, respectively. In the illustrated embodiment, the upper port 33a is formed in the partition 20, and the lower port 33b is formed in the decoupler cage 32. The main decoupler disc 31 cooperates with the main inertia track passageway 30 to provide in the vibration isolator 10, both the aforementioned low frequency maximum dynamic damping stiffness at large excitation input amplitudes and high frequency minimum dynamic stiffness at small excitation input amplitudes, as well known in the art.
For instance, a vibration isolator of this general type exhibits the typical dynamic operating characteristics illustrated in FIGS. llA and 12A, having a low frequency ,~
maximum dynamic damping stiffness at about 12-14 Hz., and a high frequency minimum dynamic s-tiffness at a much higher frequency, i.e., above about 150 Hertz (not shown).
A more detailed discussion of the theory of opera-tion of fluid filled fibration isolators may be found in an article entitled "A New Generation of Engine Mounts", by Marc Bernuchon, SAE Technical Paper Series 840259, 1984.
To limit upward motion of the cap assembly 15 relative to the cup 14 in the unloaded assembled condition illustrated, snubber means is provided. To this end, a convex retainer plate 25 extends transversely across the upper portion of the upper fluid chamber 21. The retainer plate 25 has a central aperture 25a which receives an elas-tomeric annular snubber 27 that is internally reinforced by a plate 28 and fastened to the bottom of the central core 18 by the head of the mounting stud 12. The snubber 27 engages the underside of the retainer plate 25 around its aperture 25a to limit the upward displacement of the cap 15 both in a static unloaded condition as assembled and illus-trated, and in a dynamic condition, as when the engine movesaway from the frame.
To enable the vibration isolator 10 to be assembled readily, the decoupler cage 32 is captured in a recess formed in the plate 30c in which the main passageway 30 is stamped.
In addition, the partition 20, retainer plate 25, lower flexible chamber wall 23, and spacers, are received about their peripheries in an annular recess provided between an -~v -- 10 --h lZ~7SU~ I
inturned flange 15' on the cap wall 15b and an outturned flange 14' of the cup 14. The cap flange 15' is crimped about the periphery of the cup flange 14' to complete the assembly and to render it fluid tight. Th~q may also be made as an integral drawn extension of the plate 30c.
. In the conventional fluid filled vibration isolator the ports between the decoupler disc and fluid chambers, such as the ports 33a, 33b, generally have a large cross-sectional areas and short lengths. For instance, the area of either port may be, and preferably is, at least about 80 percent of - the transverse cross-sectional area of the decoupler disc.
The length of the port is determined by the thickness of the structure in which it is formed, and usually this is about the thickness of the partition 20. Accordingly, with conventional fluid filled vibration isolators having decouplers, the lengths of the ports between the fluid chambers and the decoupler is quite short relative to its diameter, or cross-sectional area. This produces dynamic operating characteri~tics such as discussed above and such as illustrated in FIGS. 11A and 12A in the low frequency regime.
In accordance with the present invention, it has been determined that certain highly desirable dynamic effects can be achieved by incorporating within a fluid filled vibration isolator of the aforedescribed type, auxiliary inertia means having a predetermined inertia, which is less than the inertia of the fluid in the main inertia track passageway, yet which is movable relative to the chambers in response to relative alternate pressurization of fluid i ~Z97507 therein. The auxiliary inertia means cooperates with the fluid in the main inertia track passageway and with the decoupler to provide a ~elecked level of dynamic stiffnes~, or damping, at a predetermined input excitation frequency and am?litude. As will be diqcus~ed, the frequency range and the amplitude ~ensitivity of a vibration isolator incorporating the present invention can be tuned substantially independently of the dynamic operating characteristics resulting from the interaction of the main inertia track passageway and main decoupler.
In the embodiment illustrated in FIG. 1, the aforedescribed effects are Drovided by a pair of conduits 40a, 40b extending in opposite directions from opposite sides of the decoupler 31 to define a like pair of fluid slugs S1, S2. In the illustrated embodiment, the upper conduit 40a is formed integral with the partition 20 and confronts the upper surface 31a of the decoupler disc 31 via the port 33a. The lower conduit 40b extends into the lower chamber 22a from the lower surface 31b of the decoupler disc 31 and is in fluid communication therewith via the port 33b. Preferably the lower conduit 40b is formed integral with the decoupler cage 32, and has a series of peripheral notches 40' in its lower edge for permitting fluid flow in the event the lower flexible wall 23 engages the lower end of the conduit 40b in the course of operation of the vibration isolator 10.
In the embodiment of FIG. 1, both the upper conduit 40a and the lower conduit 40b are of the same length and cross-sectional area, which is preferably circular, such as illustrated In FIG. Z, and the conduits 40a, 40b are flaired 1 ~
~ ~Z975(37 in the zone of the port~ 33a, 33b adjacent the decoupler di~c 31. The fluid slug S1 defined by the upper conduit 40a extends between the topside 31a of the decoupler disc 31 and the upper chamber 21, and the fluid slug S2 defined by the lower conduit 40b extends between the underside 31b of the decoupler disc 31 and the lower fluid chamber 22. Thus, for purpo~es of explanation, the fluid slu~s S1 and S2 can be regarded as extending in fluid parallel relation with the fluid contained in the main inertia track passageway and in fluid serie~ relation with the decoupler disc 31. The combined inertias of the fluid slugs S1, S2 is less than that of the inertia of the fluid slug in the main inertia track passageway, preferably being less than about 50 percent thereof. This conduit configuration provides balanced flow conditions on opposite side~ of the decoupler disc 31 and is, therefore, highly desirable.
In operation, the vibration isolator 10 retains the conventional low frequency large amplitude and high frequency small amplitude dynamic operating characteristics discussed above. In addition, however, it exhibits an additional low frequency small ~mplitude minimum dynamic ~tiffness followed by peak damping stiffness characteristic, which is capable of ¦ being tuned independently of the large amplitude low j frequency maximum dam~ing stiffness. In the embodiment of FIG. 1, the low frequency small amplitude maximum dynamic I damping stiffness is located relatively close to the low frequency large amplitude maximum dynamic damping stiffness.
The dynamic operating characteristics of the vibratio isolator 10 may est be ob served by re f ere nce to l lZ97S07 FIGS. 11B and 12B wherein dynamic stiffne~s is plotted relative to frequency for a vibration isolator constructed in accordance with the teaching~ of the present invention. The dot-dash curve, representing the low frequency large amplitude dynamic operating conditions, is of conventional shape and exhibits a maximum dynamic damping stiffness at a relatively low frequency for a + 1.0 mm. input excitation amplitude. These curve~ compare favorably with the corresponding curves in FIGS. 1lA and 12A for the same + 1.0 mm. amplitude. However, in the low frequency range, for ~mall amplitude input excitations as indicated by the 0.25 and 0.1 millimeter curves in FIGS. 11B and 12B, the present invention provides dynamic damping stiffness maximums which are located close to the large amplitude dynamic damping stiffne~s maximums, i.e. at about 25 to 30 Hz. for idle absorption. These curves are to be compared with the corresponding curves in FIGS. 1lA and 12A, wherein for small I s amplitude input excitations, the curves are relatively flat in the low frequency range indicating low stiffness and insignificant damping.
The locations and magnitudes of the small amplitude high frequency minimum dynamic stiPfnesses are essentially unaffected by the ~tructure of the present invention. Thus, they have been omitted from the curves in FIGS. 11A-12C.
The length to diameter ratio of the conduits 40a, 40b relative to the maln Inertia track passageway 30 ~ :
I
~ I
l!
determines the magnitudes of the masses of the fluid slugs S1, S2 and thus determines dynamic operating characteristics of the vibration isolator 10. In the embodiment illustrated in FIG. 1, each conduit, quch as the upper conduit 40a, has a predetermined length to diameter ratio which is smaller than the correQponding ratio of the main inertia track passageway 30 and provides a smaller fluid inertia. For example, both conduits 40a and 40b combined have a length to diameter ratio, and hence effective inertia, which is in a range of about 15 to about 20 DerCent of the corresponding length to diameter ratio, and hence fluid inertia, of the main inertia track passageway 30 between its end openings 30a, 30b.
The dynamic operating characteristics of the isolator 10 may be varied to some extent by varying the length to diameter ratio of either, or both, of the conduits 40a, 40b to tune the isolator 10. By way of example, a doubling of the diameter of each conduit 40a, 40b, while maintaining their lengths constant, causes the low frequency small amplitude maximum dynamic damping stiffness to be shifted to slightly higher frequency levels without significantly affecting the low frequency large amplitude maximum dynamic damping stiffness level and frequency. Such shifting may be observed by comparing FIGS. 11C and 12C, corresponding to an isolator having a doubled cross-sectional conduit area, with the corresponding curves llB and 11C
corresponding to the conduit size relations discussed above.
If desired, one or the other of the conduits 40a, 40b may be omitted and some teneficial efrects retained, although it has been determined that a fluid filled vibration iqolator having only a single conduit exhiblts leqs well defined dynamic operating characteristics than those illustrated in FIGS. 11B-12C.
In the illustrated embodiments, both conduits 40a, 40b are ri8id and are dimensioned so as not normally to be engaged by either the snubber 27 or the diaphragm 23 in the normal course of operation of the vibration isolator 10. In certain applications, however, it may be desirable for the lengths of the conduits 40a, 40b to be increased. In such event, the conduit~ 40a, 40b may be fabricated of a flexible tubular elastomeric material which is readily displaceable in response to engagement by either the snubber 27 or diaphragm 23 and which, therefore, i9 capable of being moved aside in response to extreme excursions of the snubber 27 or the diaphragm 23 in response to unusual loadir.g or operating conditions. Such elastomeric tubes may be molded of various shape~, such as the shape of the decoupler cage 32, and clamped in place in a similar manner to provide both the upper and lower conduits.
The embodiment illustrated in FIG. 1 is designed to provide a single additional region of maximum dynamic damping stiffness at small input excitation amplitudes in the low frequency range. If it is desired to provide several regions of maximum dynamic damping stiffness in that range for small amplitude input excitations, modified embodiments of the present invention are provided. In these modified embodiments~ a plurality of ~xiliary inertia mean5 are I lZ~7S07 providcd in fluid series relation with the main decoupler and in fluid parallel relation with the main inertia track passageway, and decoupler means are provided for selectively controlling fluid flow therein.
In a first modified embodiment illustrated in ~IGS. 3 and 4, the decoupler assembly includes identical upper and lower shells 50, 51 confined between the partition 20 and inertia track plate 30c in the manner illustrated.
Each ~hell, such as the upper shell 50, has a central elongate upper conduit portion 50a which is surrounded by an array of outer upper conduit portions 50b-50e. See FIG. 4.
In like manner, the lower shell 51 has a similar arrangement of conduits 51b-51d arranged in like manner about the lower central conduit 51a. The shells 50 and 51 are configured in the manner illustrated in FIG. 3 to provide therebetween a decoupler cage 53 which, in the present instance, has a short cylindrical shape. An annular decoupler 54 is mounted in the cage 53 and is interposed between the upper and lower sections of the outer array of conduits 50b-50e and 51b-51e.
In like manner, a circular decoupler disc 55 is mounted centrally of the annular decoupler 54 between the upper and lower central conduit sections 50a and 51a. In the illustrated embodiment, the height, or thickness, of the decoupler cage 53 is constant and is selected relative to the thickness of the annular decoupler 54 to limit the extent of its translatory movement in the vertical direction. The central decoupler disc 55 is thinner than the annular decoupler 5~ and, therefore, ~ves through a greater dist-nce relative to the decoupler cage 53 and relative to the annular decoupler 54~ Thus, a means is provided for limiting the extent of translation of each of the decouplers 54 and 55 with respect to its associated conduits.
With this structure, the central conduits 50a, 51a and the decoupler disc 55 have a predetermined length to diameter ratio and function much like the conduits and decoupler in the embodiment of FIG. 1 to provide the aforedescribed dynamic operating characteristics of the present invention. In addition, however, in this embodiment the array of upper and lower outer conduits 50b-50e, 51b-51e, surrounding the central upper and lower conduits provide an additional fluid passageway providing an effective fluid ~lug which has an inertia that is smaller than provided by the main passageway 30 but larger than provided by the central conduits 50a, 51a. Since the magnitude of translation of the annular decoupler 54 i9 less than that of the circular decoupler disc 55, the annular decoupler 54 blocks flow through the outer conduits at smaller input excitation amplitudes than the inner decoup]er disc 55 associated with the central conduit. A~ a result, in this embodiment, essentially two different auxiliary fluid masses may be active, or inactive, depending on input excitation amplitude.
For instance, at small input excitations, both decouplers 54 and 55 simply oscillate in the cage 53. As the input excitations increase in amplitude, the annular decoupler 54 blocks flow in the outer array of conduits 50b-50e, 51b-51e, while permitting flow to continue in the central conduits 50a, 51a. However, as the amplitude increases further, the central decoupler disc 55 blocks flow through the central conduits so that all flow through the auxiliary decoupler conduitq iq arrested and the main inertia pasqageway 30 is coupled. Thus, in this embodiment multiple regions of desirable dynamic stiffness characteristics, such as discussed above, may be provided at different relatively low frequency locations and at different relatively small input amplitudes. While in the embodiment of FIG. 3, the outer conduits are of the same size and length, it should be apparent that depending upon the dynamic effects desired, either the number of conduits, thèir lengths, and~or their shapes may be varied to achieve desired tuning effects as - discussed heretofore.
:~ Rather than utilizing the thickness of the decoupler cage relative to the decoupler disc to limit the extent of translation of the central decoupler disc in FIG. 3, the annular decoupler element 54 itself may be provided with decoupler motion limiting means~ To this end, as best seen in FIG. 5, a modified embodiment is provided which is similar to the embodiment of FIG. 3, but wherein the annular decoupler element 54 has an inner peripheral recess 54a which receive~ an outwardly projecting flange 55a of a central decoupler disc 55. The height or axial thicknes~s of the reces~ 54a in the annular decoupler element 54 determines the extent of translatory movement of the inner decoupler disc 55. The central portion of the inner decoupler disc 55 is thinner than the annular decoupler element 54 but thicker than the annular flange 55a. As a result, the inner section ~ lza7su7 can both translate and flex rel~t~ve to the annular element 54 and thereby bottom against confronting conduit seat~ 50~, 51'. The function of the embodiment in FIG. 5 is similar to that of the embodiment of FIG. 3 but provides better motion control of the central element and more positive sealing.
FIG. 6 illustrates a further modification of the present invention wherein a single flexible decoupler disc 56 is mounted in the cage 53 between the upper and lower shells 50 and 51. In this embodiment, however, a continuous decoupler disc 56 is molded of elastomeric material and has a relatively thin flexible circular central portion 56a confronting the central conduits 50a, 51a and has an enlarged outer peripheral bead portion 56b located ad~acent the inner peripher~ of the cage 53. The decoupler disc 56 also has a plurality of protrusions 56c, 56d which are located on oppo~ite sides thereof and which are aligned with the upper and lower conduit sections, such as the conduits 50b, 51b, 50d, 51d, respectively. With thi~ structure, the decoupler disc 56 oscillates in a planar manner in the cage 53 in respon~e to sma]l amplitude input excitations to block flo~
through the outer array of conduits. However, as the m~gnitude of input excitations increases, the decoupler disc 56 balloons centrally due to its reduced thickness in its central region 56a. This enables the protrusions 55c, 56d more positively to block flow through their associated conduits and the ali~ned central portion 56a of the decouoler disc 56 to block flow through the central conduit sections 50a, 51a. The embodiment Or FIG. 6 funotlons In much the ~0 12975~7 same manner as the embodiments of FIGS. 3~5, but with a simpler and quieter structure.
In the preceding embodimentq, the main decoupler is constrained for translation in a cage, and the auxiliary inertia means are provided by one or more fluid columns or slugs extending in opposite directions from the cage. If desired, however, other means may be provided for mounting the main decoupler, and the auxiliary inertia means may be provided by non-fluid masses. To this end, the embodiments of FIGS. 7-10 are provided.
Referring now to FIG. 7, the vibration isolator illustrated in fragmentary cross-section is like in construction to the isolator 10 but has a central circular bore 20a in its partition 20. A main, or high frequency, decoupler element 60 is mounted in the bore 20a for translation between the upper and lower fluid chambers 21 and 22. As best seen in FIG. 8, the decoupler 60 has a ~ spool-like configuration with vertically spaced upper and - lower peripheral flange~ 60a, 60b extending radially outward from its cylindrical body portion 60c which is slidably received in the bore 20a with a clearance therebetween providing a fluid flow passage. The outer peripheries of the flanges 60a, 60b have bulbous shapes and confront upper and lower marginal surfaces of the partition 20 around the bore 20a. The axial spacing between the flanges 60a, 60b, and the thickness of the partition 20 around the bore 20a determines the extent of the vertical movement of the decoupler 60.
j Preferabl the amount o~ the vertioal mo~ement i~ limited to l 21 ~ 1297507 a small magnitude consi~tent with the amplitudes of expected higher frequency motion across the mounting. Typically this total motion is less than about 1.0 mm.
In this embodiment, upper and lower fluid conduit portions 61a, 61b, respectively, are provided centrally within the higher frequency decoupler 60 and open into an enlarged auxiliary, cr lower frequency, decoupler cage 62 located centrally within the main decoupler 60. A circular auxiliary decoupler disc 63 is mounted in the decoupler cage 62 for vertical translation between opposed confronting annular seating surfaces 62a, 62b of the decoupler cage 62.
The spacing between the seating surfaces 62a, 62b is greater than the motion clearance for the main decoupler 60 and determines the limits of translation of the auxiliary decoupler 63 in its cage 62 consistent with the lower frequency vibration levels. In the present invention, the limits of movement of the auxiliary decoupler disc 63 are greater than the limits of translatory movement of the main decoupler 60, and both can be adjusted to meet specific vibratory levels at the respective fluid inertia resonances.
In operation, small amplitude input excitations cause both the main and auxiliary decouplers to oscillate, producing a relatively high frequency fluid resonance. As the amplitude of the input excitations increases, however, the main decoupler 60 blocks flow through the bore 20a while the auxiliary decoupler 63 continues to oscillate, producing a lower frequency fluid resonance. Further increases in input excitation amplitudes cause the auxiliary decoupler 63 to bottom and thereby block flow through the conduits 61a, ~ 12975a~7 61b causing the main inertia track to become active. A~ a result, in this embodiment, the dynamic effect produced i3 similar to that provided by the embodiments of FIGS. 3-6.
Preferably, the auxiliary decoupler disc 63 is of a material having a den~ity corresponding to the density of the working fluid contained within the fluid chambers 21, 22. If desired, however, the dynamic operating characteristics of the vibration isolator can be varied by utilizing materials of different densities relative to the working fluid. Since the main decoupler 60 is preferably molded of elastomeric material, it can stretch, so that the auxiliary decoupler 63 can simply be pushed into the decoupler cage 62 through either of the conduits 61a or 61b.
In the embodiment of FIG. 7, opposed fluid slugs in the conduits 61a, 61b and the swept volume of decoupler body 60 provide the required auxiliary inertia mean~. If desired, however, embodiments may be provided having non-fluid inertia mean~. To this end, a main decoupler 65, FIG. 9, having an outer configuration ~imilar to the decoupler 60, is mounted for tran~lation in a bore 20a in a partition 20. The decoupler 65 has a central through bore 65' providing fluid communication between the upper fluid chamber 21 and the lower fluid chamber 22. A non_fluid mass, such as a cylindrical pin 66, is slidably received in the bore 65' and i~ sized relative thereto to provide a fluid flow clearance therebetween. Opposite ends of the pin 66 are provided with enlarged heads 67, 68 each having annular surfaces 67a, 68a, 12975(,~7 respectively, confronting upper and lower annular surfaces 65a, 65b on opposite sides of the main decoupler 65 around its bore 65'. Preferably, the pin heads 67, 68 have convex : end surfaces 67', 68', as illustrated, and the pin 66 is molded of a material having a density corresponding to the . . density of the working fluid in the fluid chambers 21, 22.
. In this embodiment, the limits of translation of : the auxiliary decoupler 66 relative to the main decoupler 65 are determined by the axial spacing between the pin head surfaces 67a, 68a and their respective main decoupler surfaces 65a, 65b. Such spacings are greater than the qpacing between the upper and lower flanges of the main decoupler 65 relative to the thickness of the partition 20.
As a result, the pin heads 67, 68 close off fluid flow in the main decoupler bore 65' at relatively large input excitation amplitudes while the main decoupler flanges close off fiuid flow in the main decoupler bore 20a at smaller input ............... excitation amplitudes. It should be apparent, therefore, . that the embodiment of FIG. 9 functions in much the same manner as the embodiment of FIC. 7 to provide desired dynamic . operating characteristics.
In the embodiment of FIG. 9, the auxiliary decoupler 66 is preferably molded of plastic or like materials, but may be of a denser material, such as metal depending on the inertia desired. The pin heads 67 and 68 are sized and shaped so as to be capable of being inserted axially through the bore 65', the inherent elasticity of the main decoupler 65 per=itting it t~ stretch during such I ~4 1 ~2975~7 assembly. If desired, the pin 66 may be made in two pieces for easy a~sembly. Should it be desired to augment further the inertia of the auxiliary decoupler 66, an embodiment, such as illustrated in FIG. 10, may be provided wherein opposed pin heads 69 and 70 may be formed around very high den~ity masses, such a~ lead di~cs, 71, 72. Other than for these differences, the structure and function of the embodiment of FIG. 10 is essentially the same as the embodiment of FIG. 9.
In view of the foregoing, it should be apparent that the present invention now provides an improved fluid filled vibration i olator which is designed to provide plural regions of desirable dynamic stiffness levels at predetermined frequency and amplitude locations, such as at low frequency small amplitude input excitations. This is accomplished utilizing relatively simple, yet rugged, structures capable of being manufactured efficiently by high speed mass production techniques. Moreover, the desired dynamic operating characteristics can be obtained without sacrificing to a significant extent the conventional dynamic operating characteristics of a fluid filled vibration isolator of the type having an inertia track passageway and decoupler.
While preferred embodiments of the present invention have been described in detail, various modifications, alteratLon~ and changes may be made without departing from the spirit and scope of the present invention as defln d in the appended claims.
~5
Claims (16)
1. In a fluid filled vibration isolator having a pair of variable volume chambers for containing a working fluid adapted to be relatively pressurized alternately in response to vibrations, a main inertia track passageway with ports at opposite ends providing fluid communication between the chambers and thereby providing a low frequency maximum dynamic damping stiffness at a large amplitude excitation input, and main decoupler means in fluid communication with the chambers for deactivating the main inertia track passageway at small amplitude excitation inputs while providing a high frequency minimum dynamic stiffness, the improvement comprising auxiliary inertia means movable relative to said chambers in response to said relative alternate pressurization of said fluid in said chambers said auxiliary inertia means including an auxiliary conduit in fluid communication with at least one of said chambers and said main decoupler means, and said inertia is provide by a fluid slug contained in said conduit and movable therein in response to said alternate relative pressurization of said fluid in said chambers, and said auxiliary conduit has opposed portions extending in opposite directions with respect to said main decoupler means and opening into both said fluid chambers for providing a pair Or fluid slugs on opposite sides of said main decoupler means, said auxiliary inertia means having an inertia which is less than the inertia of the fluid in said main inertia track passageway for cooperating with the fluid in said main inertia track passageway and with said main decoupler means to provide a selected level of dynamic stiffness at predetermined small amplitude low frequency input excitations.
2. A vibration isolator according to claim 1 wherein said auxiliary conduit is provided in said main decoupler means, and including at least one auxiliary decoupler carried by said main decoupler means and movable therein relative to its conduit for controlling fluid flow therein in response to said relative fluid pressurization in said chambers.
3. A vibration isolator according to claim 1 wherein said auxiliary inertia means is provided by a non-fluid element carried by said main decoupler means and movable in opposite directions relative thereto in response to said alternate relative pressurization of fluid in said chambers.
4. A vibration isolator according to claim 1 wherein said main decoupler means has a bore providing fluid communication between said chambers, and including auxiliary decoupler means mounted in said bore for translation in opposite directions between said chambers and controlling flow through said bore, and including means for limiting translation of said auxiliary decoupler means and said main decoupler means relative to said chambers and relative to one another.
5. A vibration isolator according to claim 4 wherein said decoupler translation limiting means permits said main decoupler means to move relative to said chambers a smaller distance than it permits said auxiliary decoupler means to move relative to said main decoupler means.
6. A vibration isolator according to claim l wherein said main inertia track passageway has a predetermined length to diameter ratio, and said auxiliary inertia track passageway means has a length to diameter ratio which is less than that of said main inertia track passageway.
7. A vibration isolator according to claim 6 wherein the length to diameter ratio of said auxiliary inertia track passageway means provides a fluid inertia which is less than about 50 percent of the corresponding inertia Or the fluid in said main inertia track passageway.
8. A vibration isolator according to claim 1 wherein said auxiliary inertia track passageway means includes a conduit having opposed portions extending into said chambers from opposite sides of said main decoupler and a plurality of other conduits extending between said fluid chambers, and auxiliary decoupler means operatively associated with said other conduits for selectively controlling fluid flow therein in response to selected excitation input amplitudes.
9. A vibration isolator according to claim 1 wherein said auxiliary inertia track passageway means includes a plurality of conduits extending in fluid parallel relation with one another, said auxiliary decoupler means includes a plurality of decouplers operatively associated with each of said conduits for controlling fluid flow therein, and including means for limiting the translation of each decoupler to a predetermined extent relative to each conduit and relative to said main decoupler means to provide amplitude sensitive coupling and decoupling.
10. In a fluid filled vibration isolator including a pair of variable volume chambers on opposite sides of a partition therein for containing a working fluid adapted to be relatively pressurized alternately in response to vibrations, a main inertia track passageway with ports at opposite ends providing fluid communication between the chambers and thereby providing a first region of maximum dynamic damping stiffness at a first relatively low frequency large amplitude excitation input, and a main decoupler movably mounted relative to said partition and in fluid communication with the chambers for deactivating the main inertia track passageway at small amplitude input excitations and for providing a second region of minimum dynamic stiffness at a second relatively high frequency small amplitude excitation input, the improvement comprising auxiliary inertia passageway means providing fluid communication between said chambers and said main decoupler, said auxiliary inertia passageway means being in fluid patallel relation with said main inertia track passageway and in fluid series relation with said main decoupler, said auxiliary inertia passageway containing a fluid mass having an inertia less than the inertia of the fluid contained in said main passageway, said auxiliary inertia track passageway cooperating with the main decoupler and the main inertia track passageway to provide at least a second region of maximum dynamic damping stiffness at a predetermined relatively low frequency and small amplitude input excitation.
11. A vibration isolator according to claim 10 wherein said auxiliary inertia track passageway includes a plurality of conduits arranged in fluid parallel relation with one another and in fluid series relation with said main decoupler, said main decoupler being cooperable with said conduits to block fluid flow through at least one thereof in response to input excitation amplitudes of a predetermined magnitude and to block flow through others in response to input excitation amplitudes of a different magnitude.
12. A vibration isolator according to claim 11 wherein said plurality of conduits are arranged in an array in parallel relation between said chambers and have opposed portions on opposite sides of said main decoupler means, one of said conduits being located centrally in said array and being operatively associated with said main decoupler means for effecting said selected control of fluid flow in said conduits in response to input excitations of selected different amplitudes.
13. A vibration isolator according to claim 12 wherein said auxiliary decoupler means includes an annulus operatively associated with said plurality of other ones of said conduits for controlling flow therein, and said main decoupler includes a disc located centrally of said annulus and operatively associated with said one central conduit.
14. A vibration isolator according to claim 13 including means for permitting said central decoupler disc to translate relative to said one central conduit an amount greater than the amount said annulus translates with respect to its associated conduits in said array.
15. A vibration isolator according to claim 12 including a flexible decoupler disc having an enlarged peripheral rim and a plurality of protrusions on opposite sides thereof operatively associated with said plurality of conduits for effecting said flow blocking action.
16. A vibration isolator according to claim 10 wherein the inertia of the fluid in said auxiliary inertia track passageway is less than about 50 percent of the inertia of the fluid in said main inertia track passageway.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US88698186A | 1986-07-16 | 1986-07-16 | |
| US06/886,981 | 1986-07-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1297507C true CA1297507C (en) | 1992-03-17 |
Family
ID=25390201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000535911A Expired - Lifetime CA1297507C (en) | 1986-07-16 | 1987-04-29 | Fluid filled vibration isolator having plural tunable dynamic stiffnesses |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6330624A (en) |
| CA (1) | CA1297507C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114562536A (en) * | 2022-01-24 | 2022-05-31 | 宁波拓普集团股份有限公司 | Semi-active suspension |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6018003B2 (en) * | 2013-03-26 | 2016-11-02 | 株式会社ブリヂストン | Vibration isolator |
| US10544851B2 (en) * | 2017-02-23 | 2020-01-28 | Ford Global Technologies, Llc | Vehicular vibration isolation system and apparatus |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60113835A (en) * | 1983-11-22 | 1985-06-20 | Bridgestone Corp | Vibro-isolating device |
| CA1226230A (en) * | 1983-11-23 | 1987-09-01 | Richard A. Muzechuk | Hydraulic-elastomeric mount |
| JPS60132145A (en) * | 1983-12-19 | 1985-07-15 | Bridgestone Corp | Vibration isolator |
| JPS60179541A (en) * | 1984-02-27 | 1985-09-13 | Nissan Motor Co Ltd | Liquid charged power unit mount device |
| DE3407553A1 (en) * | 1984-03-01 | 1985-09-05 | Continental Gummi-Werke Ag, 3000 Hannover | HYDRAULIC DAMPED ELASTIC BEARING IN PARTICULAR FOR THE DRIVE ENGINE IN MOTOR VEHICLES |
| JPH0754131B2 (en) * | 1984-09-07 | 1995-06-07 | 株式会社ブリヂストン | Anti-vibration device |
| FR2592114B1 (en) * | 1985-12-24 | 1989-12-29 | Hutchinson Sa | IMPROVEMENTS ON HYDRAULIC ANTIVIBRATORY SUPPORTS |
-
1987
- 1987-04-29 CA CA000535911A patent/CA1297507C/en not_active Expired - Lifetime
- 1987-07-16 JP JP17609787A patent/JPS6330624A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114562536A (en) * | 2022-01-24 | 2022-05-31 | 宁波拓普集团股份有限公司 | Semi-active suspension |
| CN114562536B (en) * | 2022-01-24 | 2024-05-17 | 宁波拓普集团股份有限公司 | Semi-active suspension |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6330624A (en) | 1988-02-09 |
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