Note: Descriptions are shown in the official language in which they were submitted.
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IITl.E: P~S"U~E RESIST~I~TT ~CCUI~L~TOR DEVICE
AI~D METHOD OF l~ .ING Sr~
EACKGROU~D O.' T~E INVENTIO~
EIEI~ OF T~-IE II~TION
The present invention is in the field of aceumul.ltor
aevi.ces and rel~tes more partieularly to an aceurnulato
deviee ~Jhich comprises a pressure vessel having an oil
port at its lower end, a cap rr.ember at lts upper end, a
gas eharging valve assembly mounted in the eap rnember and
an inlerior bladder assembly~ IJhieh divides the vessel into
t.~lo chambe~s in communication respeetlvely with the oil
port and thP ~as eharJing valve asseinbly.
THE PRIOR ART
With the proGressively increasing use of hydraulic
accumulator devices for energy storage and for pulsation
dampening as ~ell as other uses,inereasing emphasis has
been plaeed upon eonstructing such aeeurlulators in a
manner i.n wh~ieh they may be eeonomieally manufaetured and
yet provide a high de~ree of resistance to the precsures
ZO to whieh they are sub~'ected in use. l~no~n aceumulators
ean be n~anufactured by a proeedure ~hieh i.nvolves forming
threat3ed eonnectlorls on the press~ire -~essel and on the
cap rr.er~ber u-~ed to clo e one end tl-lereof Such de~.ices
a'ter ~sse~:ic~ and ~ith the intraciueti)n bet:Jeen the
assembled parts o~ ~ppr:,priate O-rin~s or like gaC~eting
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are capable Or ~iths-tanding nigh pressures without danger
oI axial separati^n of the cap from the pressure vessel.
~owever, it ~ill be readily rec~gnizea that the aperPti3n
of f3rming the pressure vecsel and the cap as by 2 forging
operation and subsequently r.~achi.ni.ng the nece~sar~J threaded
connections ~n the n~ted components is an extrerrely costly
one li.miting the r~nge of uses with whlch the accurnulat~r
rslay be ec~nornically ernployed.
Numerous me3nC have been suggested for effecti~ely
uniting the cap member over the open end of the pressure
vessel to effect a pressure resistant connection between
such parts. Such means have included rolli.ng steps wherein
the metal of the components are deformed into an inter-
locking enga~ement. By way of example, of a means of
connecting such components by rolling or spinning,reference
is made to U.S. Patent 4~2~0,533. As will be readily understood
by tho6e skilled in the metal forming art h~-~ever~ rolling
or spinning to define sharp bends or interc~nnections is
limite~ to metals ~f relatively small thicknes~ and thus
accumulators form~d in such manner are n3t suited to high
pressure operation. hdditionall.y~ the roll forming of
metals about shqr~ bend lines o~ten effects cry~taliz~ti.on
of the r.~_tals in the derormed areaC .ith re~ultant lea~en nC
o~ the metallic structures.
~ furt!ler me~l!od in c~r.~mon uce Jor connecti.ll~ the cap
carnponents ~r an accurr!ula ,r t~ the pressure -~e~sel
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3~componen-t involves an assernbling of the noted parts and
the formatian of a weld between the outer wall portion
of the vessel and the down~Jardly directed surface of the
cap. However, in high pressure operations, the weld
connection particularly at its interface with the ou-ter
wall porti~ns of the pressure vessel has been known to
shear or separate with resultant leakage, and under
extreme conditions, the cap may be blown clear of its
connection to the pressure vessel.
SUM~RY OF THE INVENqION
The present invention r~ay be summarized as directed
to an improved accumulator device and method of making
same characterized in that the components of the
accumulator na~ely, the pressure vessel, the bladder
assembly and the cap member are interconnected by a series
of three annular welds. Importantly, to the resistance of
the assembly to radial and axial f~rces resulting from the
high pressure, two of such welds are effected bet~een the
cap member and pressure vessel, one being the essentially
conventional exterisr weld and another being a continuous
annular interior ~Jeld between the upper edge of the vessel
and interior ~ide wall portion of the cap. Such construction
pr~v-ldes a far higher degree of iadial and axial precsure
re~istance l;han the conventi~nal single exterior weld
construct ion.
An important aspect of the invention re~ides in the
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provi.sion of a mounting skirt weldingly c^nnected to the
interior of the pressure vessel and utilized as the support
for the bladder assembly. Such mounting skirts are known
per se. Ho~ever, in accordance with the instant invention
the uppermost end of the skirt is caused to extend a
distance above the open mouth po.rtlon of the pressure
vessel, whereby there is de~ined bet.ween the i.nterior surface
of the cap and the up~ardly extending end portion of the skirt
of the bladder assembly, an annular trough for the formation
of the interior weld. The provision of such trough acts to
prevent the flow of ~Jeld material into the interior of the
bladder with resultant damage or destruction of the bladder.
The invention is further directed to a novel method
of manufacturing a high pressure resistant vessel in
accordance with which method access to the t~eld area formed
interiorly of the devi.ce is effected through the aperture
i.n the cap which will support the gas charging valve assembly~
In accordance with a further aspect of the method the
cap member may be applied in an initially.cylindrical
configuration of ~Jall thickness preferably substantially
close to tile wall thi.c~ness of the pressure vessel and
thereafter s~un or formed into the part nemispherical
configuration typically employed in accumulator device ,
It i.s to be not.ed that the f~rmation by spinning or rolling
doe~ not require the production of any sharp berlds whereby
such operation is suitable for use l/~ith thick ~/alled
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materials and does n~t result in metal crystalization
pr~blems .
It is accord ingly sn ob ject of the invention to
provide a n vel h-.~h pressure resistant accurnulator device
A further objiect of the invention is the provision
oI an accumu]at~r device of the type described ~;rherein
a cap member, t.hich will carry the gas chargin~ valve
assembly, is secured to the pressure vessel by two
annular ~Jeld connections thus greatly increas ing the
resistance to separation ~f the cap from the vessel and
hence increasing the pressure capability thereof.
Still a further 3bject of the inven-tion i,5 the
provis ion of a method of manufacturing a high pressure
resistant hydraulic accumulator device ~rhich includes
the step of effecting an interior weld bet.~een the cap
member and the upper end of the pressure vessel, such
interior ~eld being effec ted through an opening in the cap
member which ultimately carries the gas charging valve
assembly
Still a further ohject of the invention is the
provision of a method of rnaking an accumulator ~3evice as
descr-, bed ~hi.ch includes the step ;~ f for ning the cap
nernber to i~s end c~nfi~,uration after the cap has been
eldin~ly connected by bo-th an ini.erior arl~3 e~teri~r ~eld
to the body of the prescure vessel.
Thus, in accordance with one aspect of the present
invention there is provided an accumulator device comprising
a pressure vessel including a closed end having an oil port
and an open end, said open end terminating in an upwardly
directed edye portion, a bladder subassembly mounted in said
open end~ said sub-assembly including an axially elongated
metallic mounting skirt having a bladder fixedl~ secured to
one end thereof, said mounting skirt being disposed within
said vessel with said one end nearest said closed end of
said vessel, at least a portion of the outer wall portion
of said skirt intimately engaging the inner wall portion
of said vessel adjacent said open end, said skirt including
an upper end portion e~tending above said open end of said
vessel, a cap member having an opening ~or the reception of
a gas charging valve, said cap member being positioned in
closing relation of said open end, said cap member including
a depending skirt outwardly lapping said open end, said cap
member including a downwardly directed edge portion, said
upper end portion of said skirt, edge portion of said vessel,
~0 and inner wall portion of said cap member to~ether defining
an annular trough, a first continuous annular weld connection
formed between said mounting skirt and said vessel at
engaging portions thereof, a second continuous annular weld
connectio~ received within said annular trough and connecting
said edge portion and the inner wall portion of said cap
member and a third continuous annular weld connection
formed between said edge portion of said cap member and
outer wal~ portion of said vessel.
In accordance with a further aspect of the present
invention there is provided a method of fabricating a
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pressure reslstant accumulator device which includes a
pressure vessel having a closed end including an oil port,
and an open end having an upwardly directed edge, a bladder
assembly including a metallic mounting skirt, and a cap
member having an opening for the reception of a gas charginy
assembly, said cap member including a depending skirt
terminating in a downwardly directed edge, which comprises
the steps of so inserting said mounting skirt into said
vessel that an upper end portion of said skirt ex-tends above
said open end of said vessel, forming a first continuous
annular weld connection between said moun-ting skirt and
said vessel, causing said skirt of said cap member to be
mounted over said open end of said vessel with said upper
end portion of said skirt, edge portion of said vessel,
and inner wall portion of said cap member together defining
an annular trough forming a second continuous annular
connection within said annular trough and connecting said
edge portion and the inner wall portion of said cap member,
and forming a third continuous annular weld connection
between said edge portion of said cap and outer wall portion
of said vessel.
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In order to attain these ob~ects and such other
objects as may be hereinafter pointed out reference is
made to the accompznying drawings in which:
Fig. 1 is a vertical section21 view thraugh ~
pressure vessel in accord2nce with the invention in a
partly finished c~ndition.
Fig. 2 is a magnified fragmentary section of
the pressure vessel of Fig. 1 in finished condition.
Fig. 3 is a fragmentary vertical section sirl~ilar
to the section of Fig, 2 of a further e~nbodiment of the
invention.
Referring now to the drawings there is shown in
Fig. 1 a partially finished a~cumulator device which
includes a pressure vessel 10 having an oil port 11 at
its lower end, an internally threaded nipple 12 being
provided to enable the vessel to be connected to the
hydraulic line of a system incorporating the accumulat~r.
The pressure vessel 10 includes an open mouth portion
defined by the upwardly directed end face or upper edge 13
of the pressure vessel. Preferably~ the eAterior ~rall
portion 14 ~f the pressure vessel includes an cnnular groove
or recess 15 adj~cent the upper end of tne vessel fnr
purp~ses which l'rill appear hereina~'ter,
The device includes a bladder assembly 16, s~id
assembly including a retainer Member or skirt of metallic
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~aterial 17 on which is supported a elastomeric bladder
member 18. The bladder member 18 may include at its
lower end lg~ a ri~ld button 20 kno~rn per se, which
button functions in the distended condition of the bladder
to seat against the oil port 11 and seal the same. The
skirt 17 may include in~ardly directed flange 21 on
~Jhich is mounted b~ a carlbine~ b~nding and adhesion
proQess, a thickened rim porti~n 22 of the bladder.
The accumulator device includes a cap member or
sub-assembly 23 ~hich will ultimately carry the gas
charging valve assembly 24 (see Fi~. 2).
There will now be described the sequence of steps
employed to convert or asse~nble the elements hereinabove
described to the finished accumulator assembly illustrated
in ~ig. 2. As an initial step, the bladder assembly 16
is inserted through the open mouth or end 13 of the
pressure vessel in such manner that the uppermost edge
25 of the skirt 17 extends a short distance "d" above the
level of the upper edge 13 of the pressure vessel. With
the skirt 17 thus positioned relative t~ the pressure
vesse~ an annular resistance ~eld Ir-l is .or~ed bet:~een
the skirt 17 and the vessel in the area in registry ~ith
the groove 15 ~ ~ne p,essure vessel. The purpose of
providing the groove or recess 15 i~ to le~ve a rel2tively
thin ~etal ~all sect~on 15' in the pressure vessel.
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Preferably the thickness of the wall porti~n 15' ~f the
pres~ure vessel aligned with the groove 1~ is substantially
identical of the wall thickness of the skirt 17 t~ facilitate
the formation of a resistance weld.
After the bladder assembly 15 has been connected to
t.he vessel 10, the cap member 3 s slee~ed o~er the end
13 of the vessel to the positian shown in Figs. 1 and 2
With the parts positioned as shawn~ a second continuous
annular ,Jeld W-2 is effected between -the upper edge 13
of the pressure vessel and the interior wall porti~n 26
of the cap assemb]y 23.
~ s will be apparent from an irlspection of Figs. 1
and 2, by virtue of the upper end 25 of the skirt extending
above the edge 13 of the pre~sure vesselg there is defined
between the cap 23 and the skirt 17 an annular trough T
for reception of the ~Jeld W-2~ This trough assures that
debris from the formation of the weld W-2 will not fall
into the interior o~ the bladder with possible consequent
damage either immediately from burning or subsequently
~ from the presence of metallic particles. Optionally, and
as 2 further precauti.on agair.~st danage to the bladder, the
same may be filled ~ith water during formation of the
~r~eld W-2.
~ inally, the ~,ield W-3 is forr:ed, the sarne being a
continuous annular ~eld l~hi.ch lin~s the (~.Jn~ardly
directe~ e2ge ?~ of the cap 23 with the e~terior wall
portion 29 of the pressure vessel 10. It will be
understood that -the sequence of formation of the welds
~-2 and ~J-3 is op~ional,
After the parts have been connecteci in the manner
hereinbefore described~ the cap member 23 may be deformed
in~ardly to the configuration shown in Fig. 2 which
cperation lrill result in the format~or of a part hemi-
sp~leric portion 30 having a narro~Jed central gas port 31,
The gas charging fitting 24 may be connected as by wéld
32 to the gas charg~ng port 31 completing the a~sembly of
the accumulat3r device,
~ en the completed accumulator is under pressure, the
portions of the welds W-2 and W-3 bonded to the exterior wall
29 of the pressure vessel and the inner wall sur.ace 26 of
the cap 23 will be subjected to shearing forces and the
portianC of the ~Jelds IJ-2 and W-3 bonded to the end 13 of t~e
pressure vessel and the end 28 of the cap 23 ~ill be subjected
to tension forces, ~ne effectiveness af the retention areas
subjected to tension forces to prevent separation of the cap
fram the pressu~e vessel is far rT~eater ~han the effective-
ness of the retention ~reas subjected to shearing forces,
~:cc-,rdingTl~, an accu"ulatc)r of the typP hOvlng 2 C2p secured by
t~lo lelds to a she:ll or pressure vessel c-n ~!ithst2nd far
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higher pressure before separation of` the cap I'rom the
shell than an accumulator of the same type wi-th but a
single weld to h~ld the cap and the shell together.
In the embodirnent af Fig. 3 ~jherein like part~
have been given li~e reference numerals~ the ssle
dif'ferences bett!Jeen the first descri.bed embodiment
resides in the fac~ that the cap rnember 23 a has
already been preformed to its part spheri.cal configura-
tion, The cap member 23 a includes a gas charging port
31 q of relatively large diameter. Additionally~ the
uppermost end 25 a of the skirt 17 a is inclined up-
wa.rdly and radially inwardly toward the gas charging
port.
By providing the components in the configurati~ns
noted, it is possible with the embodiment of Fig. 3 to
effect the weld W-2 by inserting a l~7elding rod through
the gas charging port 31 A in the direction illustrated
by the arrow 33. The bent or inclined configuration Or
the upper p~rtisn 25 a of the ski,rt provides additional
clearance for insertion of the welding mechanism.
~ s will be apparent t~ th~se skilled in the art
numerous variakions in -the described construction and
sequence of metho~ steps mab~ be r.ade ~Jithout depzring
Irom the spirit of the invent'on. ~!ccsrdingly, the
~ame i.s to be broadly csnstrued ~Jithin the scope of the
appended claims.
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