Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND ANI~ SUMMARY OF THE INVENTTON
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It h~s heretofore been the practice in the construction ~:
of piston assemblies for vehicle shock absorbers to utilize valving
arrangements of the single valve disc type and also of the multiple
valve disc type. A typical single valve disc piston arrangement
i6 shown in French Patent No. 2,146, 611, while a typical multiple
valve disc arrangement is shown in United States Letters Patent
No. 3,134, 460. Each of these valving arran~elnents has been subject -
~o e~rtain objections from shock absorl~er manufacturers ~nd it is a
:~ genoral objeot o~ tho pre~ent invontion to provide R new and improvod
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p:iston assembly which overcomes such objectionable character-
.istics oE both single-disc and multiple-disc plston valving
designs. In partic~llar, the use of single-clisc valvin~ re-
quires that both the rebound and eompression loading on the
valves he matehed. Consequently, i-t has been almost impossible
to proviAe accurate adjus-tment of the rebound loading of sueh
a shoek absorber design without ehanging the eompression load-
ing thereof. A related problem relates to the fatiguing o~
the valve parts whieh in turn results in eertain performanee
limitations in order to assure against premature valve failure.
Insofar as the multiple-dise valve arrangements
mentioned above, the pistons assoeiated therewith have been
found to be relatively expensive to manufaeture and although
permitting independent changes of the eompression and rebound
eontrol, such multiple-disc pis-ton valving, sueh as shown in
the aforementioned United States Letters Pate.nt No. 3,134 r 460
has been found to be objeetionable from the s-tandpoint that
the bleed eontrol on rebound and eompression eannot be ehanged
independently of one another. Beeause low speed control has
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beeome signifieantly more important in modern automotive
vehieles, sueh independent eontrol of the rebound and eompress-
ion loading on low, as well as high, veloeity piston movements
has beeome almost mandatory.
Broadly speaking, the present invention provides
~ a shock absorber assembly comprising: a pressure cylinder; a
-~ piston assembly reciprocably disposed in the cylinder; and a
:~ floating pis-ton member disposed with.in the cylinder, the floating
~ piston member dividing the cylinder into a fluid chamber and a
- pressurized gas chamber, a quantity of hydraulic damping fluid
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and t:he piston ass~ bly bcincl locatecl in the fluid chamber,
and a quanti.ty o~ press~lriæecl gcls beinc7 located in the
pressuri~.ed gas chan~er; the piston assembly comprising
first and second coaxially arranged piston members each
having radially i.nwardly c~d outwardly sets of axially extendin~ flcw
ports, a compression valve assembly disposed adjacent one
side oE one of the piston members, a rebound valve assembly
disposed adjacent one side of the other of the pis-ton members,
each of the compression and rebound valve assemblies compris-
ing at least one disc~like valve member movable toward andaway from associated valve seats, an intake valve assembly
disposed between the piston members for selectively controll-
ing fluid flow between certain of the flow ports of one of the
members and certain of the flow ports of the other of the
members, the intake valve assembly comprising first and
second disc-like intake valve members, one of the members being
cooperable with a valve seat on one of the piston members and
the other of the valve members being cooperable with a valve
seat on the other of the piston members, and a common spring
element interposed between and arranged coaxially cf the first
and second valve members for resiliently biasing the same toward
engagement with the associated of the valve seats, the compression,
rebound and intake valve assemblies comprising the entire valve
means for controlling fluid flow within the shock absorber where-
: by to permit changi.ng the rebound and compression characteristics
of the shock absorber solel~ by changing the appropriate of the
valve members.
Thus, the present invention is di.rected -toward a
new and improved pis-ton design which obvia-tes the aforementioned
objectionable features of prior art piston and pis-ton valving
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~les1~n~ tllro~l~h ~1~e l)rovision Or a pis~on assoml)1y con~prl~ln~ a
pnlr Or p1ston nlcmbcrs or bod1es which arc identical In cons~ruction
and hencc can bc madc to bc lntcrch~n~cablc. Vlsposcd bctwccn tl1e
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plston membcrs is a pair of intak~ valves which are resillcntly biascd
apart or ~oward en~a~emcnt with the piston mcmbers by means of a
sprlng disc located therebetwc(!n. A rebound valve assembly is
dlsposed adjacent one side of one of the piston members and consists
of one or ~ore valve discs and an associatecl orifice disc. In a
slmllar manner, a compression valve assembly is disposed adjacent
the opposite side of the other of the piston members and likewise
lncludes one or more valve discs and an associated orifice disc.
With this arrangement, it is possible to use rebound and compression
ortfice discs which are completely different and hence may be
adjusted independent of one another for modifying low speed control
during both rebound and compression. It is accordingly another
object of the invention to provide a new and improved piston design
îor use in automotive shock absorbers which compr1ses independent
rebound and compress ion bleeds which may be adjusted independently
of one another.
Another feature of the aforementioned construction
r~sides in the fact that the valve aiscs of the compression and
~bound valve assemblies may con~prise diîferent size and thickness
re discs (or valve discs of the same size and different thickness
o~ the a:me tl-lckness :Ind difrcrent si7es), wl~ereby the blovr-of~
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control s)f thc pl.ston m;ly bo contrvl]cd indcpendcnlly ot onc anolIIcr
durln~ botII rcbountl ~nd comprc~slon opcrt~tlon Or tho plston.
. I~nother ~c~ture of the prescnt Invcntlon reslclcs ln tho
fact that a spacer mcmber is disposed diractly adjacont the rcbound
and compression valvc dlscs, the thlclcnass of whlch sp~cer mcmbers
may be controlled so as to provide for further blow-o~f control.
it Is accordingly a further object of the present lnvention to provide
forblow-off control by varyln~ the numbe:r, sl~e ~both thlckness
and diameter) o~ the valve disc and the associated spacer me~bers.
~:~ It Is another object of the present inventlon to provide
a new and irnproved automotive shock absorber piston design of ~:
the above-described character wherein high speed control may be
efîected by controlling the size of the selected of the ~low par~s ~ .
In one of the piston members and similarly controlling the size of
selPcted of the flot,v ports in the other of the piston members.
A related prior art construction is shown in United
States Letters Patent No. 3,13~,460; ~herPin multiple piston
bodies are depicted In~Figure 4, however, one critlcal tiffemnce
between this prior art design and the present inventlon resides in
the fact that in the prior art piston, each piston body gives part of : .
the rebound control and part of tXe compression control, and it is
~ot possible to have an independent bleed control as i5 the case
wlththe present inventlon wherein one piston gives rebound control
and the other piston ~ives compresslon co~trol, It Is accordingly ~:
an addltional objcct or thc prcsent invention to provide a new and
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Improvcd plston de~ n ovcr the Rrrnn~emCnt shown In thc aforc-
mcntloncd Unitcù ~tatcs Lcttcrs l~atont No. 3,13~,~G0,
. tt l~ stlll slnothcr objcct Or thc prcscnt lnvcntion to
provltlc a new and improvccl vchicle shocls absorbcr piston clcsi~n
wherein a plurality of thc cornponents thereln are Intcrchangcable
~o as to minimize to the extreme the required toolln~ and resultant
man~lfacturing expenses.
OLher objects and advantages of the present invention
wlll become apparent from the following cletalled descriptiorl of
the preferred embodiments taken in conjunction with the accompany-
Ing drawings.
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- BRIEF DESCRIPTION C)F THE DRAWING
lFIgure 1 is a longitudinal cross-sectional view of a
typical automGtive vehicle shock absorber embodying the principles
of the present invention;
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Flgure 2 is an enlarged fragmentary cross-sectional
vlew of the piston assembly embodying the principles of the present
ll~vention and depicted in Figure 1; and
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Figure 3 is an exploded assembly view of the piston shown
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In ~igure 2.
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~; ; ESCRIPTION OF ~ PR~;-F ~K--D EME~ODI`,IE`IY
eferring now to Figure 1 o~ the drawing~ a shock
absorber unlt 10, in accordancc with one pre~erred embodiment oE
ehe present invention, is shown gener~lly as comprisin~ a pressure
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cylInclcr 12 tl;lving a reclprocal)lt piston as~cml~ly 1~ con~truetcd
In nccor~la~icc wi~h tha principlcs of thc pI~cscnt Invcntlon disposcd
thereIn. The assem~ly I4 Is mounted on one ond oî a recIproc~blc
plston rod 16 which has the opposite end thereof projcctlng axlally
outwardly irom the cylinder 12 and providcd with an end fitting 1~.
Thc oppositc end of tbe cylintler 12 is provitled with another end
~Ittlng 20, whereby the unit 10 may be operatlvely mounted between
the sprung and unsprung portlons of the associated vehicle for
damping relative movement therebetween, as is well known in the
art. The shock absorber unU 10 is provided with a dirt shield
assembly 22 which includes a cylindrical section 2~ arranged
coaxially of the piston rod 16 and spaced radially outwardiy from ~;
he outer periphery of the cylinder 12, as illustrated. The section
24 ls connected to the piston rod 16 by means of a generally cup-
shaped end member 26. ;~
The interior of the cylinder 12 is provided with a fluid
chamber 28 within which a quantity of hydraulic damping fluid is
located, and also with a pressurized gas chamber 30, the chambers
~8 and 30 bemg separated by a floating piston me~nber 32 in a
manner well known in the art.
Referring now in detail to the construction and operation
of tbe piston assemblg 1~ of the present invention, as best seen In
Flgure 2, the piston rod 16 is pro~Jided with a reduced dia~eter
end section 34 which is defIned by a generally radîally disposed
~houlder 36 and include~ an e~tern~lly tl~readcd terminal ead portion ~`
38 upon whIci1 a sult~ble nut 40 ls thread~bly recei~rcd ïor retainIng
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thc as~cm1)1y l~i ln itY opcrtltlvc ~ositlon UpUIl thc p1ston rod 16.
The pl~;ion .~,scInbly l~ comi~riscs a l)a1r of klentical pistor1 bocllc.;
or mcm~ers, onc of which ls klent1~led hy thc nmoral 42 anc1 the
othcr of wl1ich is idcntifie(l by like n-lmerals with a pr1me ~') surrix,
w1th the followin~ dcscription of the pistor1 body 42 bein~ applicablc
to both bodies ~2 and 42'. As best scen 1n Figure 2, -thc piston body
~2 ls provided with a Elrst plurality Or circumferent1a.11y spaced
ax1ally extending flow por$s 44 and with a second plurality of cir-
cumferentially spaced axially extending flow ports 46 that are located
radially inwardly from the flow ports 44. The upper side of the
piston body 42 defines an upper surace 48 which is ~ormed with
an annular valve seat 50 that is located radially between the flow
ports 44 and 46 and extends concentrically around the upper side
of the body 42. The lower side of the piston body 42 ls de~ined by
a bottom surface 52 which is in turn formed with a pair of coaxially
arranged radially inner and outer valYe seats 54 and 56. As illustrated,
the valve seat 54 is arranged generally axially below the valve seat
50, while the valve seat 56 is arranged radially outwardly from the
outer plurality o~ flow ports 44 It is to be noted thst in the assembly
14~ the piston body 421 is inverted relative to the piston body 42,
~srlth the result that the valve seafs 54' and 56' ex$end upwardly from
th~ plston body 42', as opposed to extending downwardly as is the
~ase with the piston body 42. The piston body 42 is formed with ~
~ntral annular opcnin~ 57 which is adaptcd to receive the reduced
d1ametcr end section 34 o~ the piston rod 16, with the body 42' being
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~orme~l witll an ldcn~lcal cenlrLIl opcnin~ 57' s~ntl l~cin~ nt~aptcd to
}lkcwi~c rcceivc tllc cn~l scetion 3~, with ~ ro~ult thilt thc pi~lon
bodles ~2, ~2' will bc coaxially arran~cd ~ith rcspcct to onc anvtller
In a manner bcst seen in I; igurc 2,
Dlsposed betwecn thc piston bodics 42, 42' Is a pair of
Intake valve discs 513 and 60 that are fabricated of a suitable spring
~teel material or the like and which are formed with central openings
62, 64, respectively, through which the piston rod end section 34
extends. The valve discs 58, 60 are adapted ~or engagement with
the valve seats 54, 56 and 54', 56', respectively and disposed
between the discs 58, 60 is a valYe spring disc 66 which is also
formed with a central opening 68 and comprises a plurality o~
circumferentially spaced radially extending undulations 70 (see
Flgure 3) ~vhich function to yieldably maintain the valve discs 58, .
60, operatively engaged with the associated valve seats of the piston
bodies 4û, 42. .
- I:)isposed centrally oi the valve discs 5~, 60 and the . :
: sprtng discs 56 is a central positioning spacer or spider, generally
d~signated hy the rlumeral 72. The spider 72 is fs:~rmed with a
central opening 74 through which the piston rod end section 3~ extends,
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and the spider 7~ cludes a pluraliiy (preferably three) of circum-
~eret~tially spaced radially outwardly extending arms 75, the radially
sutermost portions of which terminate adjacent the irlner periphf~ry
of the mcmbers 58, 60 and 66, whereby to limit ~novement Or these
members ln a radial plane. If deslred, an optional piston ring,
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r~prcscnl;ltIvcl,y Llcsi~natcLI l)y ~hc numcr~l 7II, ~nay hc ~rraLl~cll
radially o~ltwar(lly from ~hc valvc di~cs 58t G0 ;lnll sprin~ dlscs GG
and ndap~ed for sealillg en~agement with thc lnncr pcripllery of lhc
cylIntler 12 in a manncr wcll known ;n the art,
DIsposed acljacent the uppcr side of the plston body ~2
Is a compression valvf~ assembly 80 which comprises a pair of
6prlng steel or the like valve dlscs 82 and 8'L ~Nhich are forrned
with central openings 86, 88, respectively, through which the piston
rod end section 34 extends. Interposed between the underside of
the valve disc 84 and the valve seai 50 is an orifice disc 90 that is
formed with a central opening 92 ànd with a plurality of radially
Inwardly extending notches 94 around the outer periphery thereof.
As illustrated, the outer diameter of the valve discs 82, 8~ and the
orUlcè disc 90 are appro~cimately equal and are all slightly larger
In diameter and therefore project slightly radially outwardly beyond
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the valve seat 50, with the notches 94 being generally axially
-~ aligned with the valve seat S0, whereby to permit limited fluid f1OW
~b1eed) between the disc 90 and the valve seat 50.
Arranged dlrectly axially above the valve disc 82 is a
spacer ring 96 which is formed with a central op~rling 90 through
lch the plston rod end~ section 34 extends and arranged directly
above the spacPr ring 96~ is a support washer 100 which is formed
wlth a central opening lO2 and is positioncd directly against the
underslde o~ the shoulder 36, as Illustrated. As will hereinaft~r
b~ described In dctnil, the comprcssion val~te assembly 80 functions
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to c~nlrol lhe Ill~w Or Qukl pu.qsing ur~ward1y throu~l~ thc plur;lllly
~r porls ~iG ~f thc piston hody 42 ;IS tlle piston assoml)ly 1~ movcs
downw~rtlly (durin~,~ a comprcsslon strokc) witllln thc îluid chaml7cr
2~
A rebound valve assembly 10~1, which ;s similar in
eonstructton to the a~orcmentioncd compression valve assembly
80, ls disposed adjacent the underside of the piston bocly 42'. The
assembly 104 comprises a pair oî sprLng steel or the lilcc valve
disc~ 106 and 108 that are formed with central openings ~10 and
112, respectively, through which the pist~n rod end section 34
projects. Disposed interjacent the upper side of the valve disc 108
and the valve seat 50' is an orifice disc 114 whlch is also îormed
with a central opening 116 and a plurality of radially inwardly ~.
e~:tending, circumferentially spaced notches 118. A spacer ring
120 having a central opening 122 is located directly axially below
the valve disc 106 and a support washer 124 having a central opening
126 is located between the spacer ring 120 and the nut 40 which is
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` threaded on the end portion 38 of the piston rod 16 in a manner so
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~ as to maintam the support washers 124, 100, spacer rings 120, 96,
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v~h~e discs 106, 108, 82, 84, orifice discs li4, 90, piston bodies
~2, ~2' and spider 72 in a state of compression between the nut 40
- andthe shvulder 3
In operation of the shock absorber 10, during a com-
pr2ssion strvke, I,e. downward movement of the piston assembly
14 wlthEn thc cylindcr 12, oil flows upwardly through the plurality
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of ports 4~' in tl)e pi~ton llo(ly ~2' and opetls thc v;~lve dl.~3c G0, I. c.
blascs thc v~lvc dlsc ~û upw;lrdly orf rrom ~hc valvc scats 5~'t 5G'
ngalnst thc resist;lnce of thc spr Ing disc 68. Thc oil thcn ~lvw9
radlally inwarùly bctween thc outwardly projccting arms 76 of the
spidcr 72 ancl therea~tcr axially upwardly through the plurality of
flow ports 46 of thc plston body 42, Thcrea~ter, the fluid ~lows
radially outwardly between the upper side of the valve seat 50 and
l!he notches 9~ of the orifk:e disc 90 i~to the upper end of the fluid
chamber 28. At such time as the pressure acting on the valve discs
82, 84 reaches a predetermined magnitude, the discs 82, 84 will
be biased upwardly away from the valve seat 50 to permit it a greater
m~gnitude of fluid flow, i. e. during high speed movement of the
p5ston assembly 14.
I~uring a rebound stroke, io e. upward movement of the
pist~n assembly 14 within the cylinder 12, fluid Elows axially down-
wardly through the plurality of flow ports 44 of the piston 42 and
bi~ses the valve disc 58 away from the ~Jalve seats 54, 56, against
the resistance oE the spring disc 66. This nuid then flows axially
and radially between the out~irardly projecting arms 76 of the spider :
7~ and thereafter axially dowrlwardly through the plurality oE flow
- ports 46' of the piston body 42'. This nuid then flows between the
a~re seat 50' of the piston body ~L2' and the plurallty of notches
118 of the oriflce disc 114 Into the lower end of the fluid chamber ~:
2~. At such tlme as the pressure acting against the valve discs
106~ 108 reachcs a predetermined magnitude, the discs 106, 108
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wlll movc slwny rroln tllc v~llv~ .qc~tt 50', l.o. durin~ 1~i6h ~pco~l
piston movcmcnl, lo pcrmlt ;I prcdctcrmIIlcd ~rcatcr m~nitudc of
fluId flOw,
Onc particul~rly i~nportAnt fcature of thc prescnt ;
lnvcntIon rcsidcs In the fa.ct that the orificc dlscs 90, 114, may
be indepcndently changed or modifLed so as to control the low speed
operation of the shoclc absorber 10 and more particularly, so that
the rebound and compression characteristics may be changed in-
dependetItly of one another. Another feature of the present inventIon
resIdes In the fact that the valve discs 82, 84 and 106, 108 may be
varied to control the operational or performance characterlstics of
;~ the piston assembly 14. For example, the discs 82, 84 and 106,
108 may be changed by vary~ing the material, thickness, diameter
and¦or the number thereof in order to achieve the desired per-
formance. Additionally, the diameter and/or thickness of the spacer
rlDgs 96 and 120 may be varied so as to control the degree of blol,v~
off o~ the valve discs 82, 84 and 106, 108. Yet another feature of
the present invention resides in the fact that the cross-sectional
s~ze and/or number of the flow ports 44, 46 and 44', 46' may be
conYenienuy changed for varying the operational charncterist ics of
the piston assembly 14. For example, the flow ports 46' may be
~hanged to control the high speed rebound characteristics of the
assembly 14, while the flow ports 46 may be varied for controlling ~;
the hlgh specd compression characteristics of the assembly 14.
Yet anotllcr fc~turc of the present lnventlon rcsidcs in the fact that
~ large numbcr ot thP componcnts of thc ~ssembly 14 arc lntcr
;~ ~h~nge~ll)lc ~nd thus m~r be m~nut;lcturcd ~t si~nltic;~ntly rcduc~d
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tooli~ cxl-cnse~ or cx~lmplc, t~lC plF:~oll l~odlcu ~ ~n~3 ~IL2'
csln ~c lnLcrcllan~c!nl>lc, a.s can thc comprosslon and rcbo~ln~J
dl~cs and¦or the intakc valvc discs 58, 60, A furthcr feature of
the prescnt invention reskles in thc fact tllat the valve discs
Incorporatcd thcrcin are subjcetcd to si~nificantly lcss fati~1ue
than anala~ous prior art designs, with the~ reslllt that the
operational life of the piston asse~nbly 14 of the present inven-
tlon will be impro~red over such prior art designs. It is to be
slsted that while the piston assembly 14 has been shown in the
attached drawings and described above as being incorporated
in the pressurized-type shock absorber, the principles of the
present invention are not intended to be so limited, since the
present invention should find very satisfactory application in
multiple or two-tube type shock absorbers.
YVhile it will be apparent that the preferred ernbodi-
ment oI the invention disclosed is well calculated to f~llfill the
obJects above stated, it will be appreciated that the invention is
susceptible to modification, variation and change without departing
froD~ the pFoper scope or ~aiF me-ning of the subjoined claims.
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