Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
The present invention relates to pressure vessels,
and more particularly to pressure vessels of the type com-
prising a rigid casing having axially aligned ports at its
respective ends and a deformable separator dividing the
vessel into two variable volume fluid chambers communicat-
ing respectively wlth the ports. The deformable separator
i8 in the form of a bladder having a closed lower end and
a mouth with a peripheral bead. The bladder is attached at
its mouth to an annular supporting member disposed inwardly
of and fixed to the casing.
TRE PRIOR ART
Known armular supporting members are of the thick
or thin-walled construction. In the first type of annular
supporting member a groove is cut deep in the thick-walled
annular supporting member and accommodates the bead of the
bladder therein. In the second type of construction the
bead is actually molded on the end of the thin-walled annular
supporting member. Examples of the first type of construc-
tion in United States Patent No. 2,394,401 (Overbeke) and
3,168,907 (Mercier, et al.), and of the second type in my
United States Patents Nos. 3,946,759 and 3,830,259.
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~,
It has also been proposed to clamp the bladder
between a supporting member of thin-walled construction and
the casing, ~ust below the bead on the bladder which is then
received in an annular groove in a hook-like portion of
the supporting member as disclosed in United States Patent
No. 3,948,287 (Sugimura, et al.). Such clamping of the
bead occurs precisely where traction and flexure forces on the
bladder are greatest and is a cause of considerable fatigue
shortening the service life of the bladder.
SUMMARY OF THE INVENTION
A principal object of the present invention is to
provide a pressure vessel having an annular supporting
member of the thin-walled type having a specially formed
hook-lik~ portion coacting with a complemental bead on the
deformable separator which combineto insure trouble-free
securement of the deformable separator with consequent
long service life. A further object of the invention is
the provision of a pressure vessel which can be mass produced
at low costs.
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The present invention provides for a pressure
vessel comprising a casing of rigid material having two closed
ends with axially aligned ports and an internal vertical planar
wall, a deformable separator disposed inside said casing be-
tween said ports to define variable volume fluid chambers on
either side of said separator, said separator having a mouth and
an annular ~ead therealong, an annular separator supporting
member fixed to the internal vertical planar wall of said casing,
said supporting member being of sheet material construction sub-
stantially thinner than said casing and including a substantially
cylindrical portion adapted to bear against the internal wall
of said casing, a smoothly curved hooklike portion defining a
radially outwardly opening groove for accommodating said bead
of said separator, a connecting zone between said substantially
cylindrical portion and said hooklike portion defining a wedge-
shaped space with said internal wall, said bead being clampingly
disposed within said wedge shaped space in compressed condition
to define a fluid-tight seal between said supporting member
and said casing; and an end portion at the end of said hooklike
portion remote from said connecting zone being radially spaced
from said internal wall of said casing a distance equal to or
greater than the undeformed wall thickness of said separator
so that the portion of said separator between said end portion
and said internal wall of said casing is not compressed by said
end portion, said bead including a thickened zone facing said
internal wall of said casing such that in undeformed condition
it is of greater radial extent than the radial depth of said
groove measured to theînternal wall of said casing, and said
radial depth of said groove having portions which are at least
two and one-half times the distance between said end portion
and said internal wall of said casing, said bead having a deep
cut-a-away zone facing said end portion of said separator suppor-
ting member so that said deep cut-away zone compensates for
said thickened zone and allows expansion therein of said bead
during compression of said thickened zone so as to prevent
pinching of said separator in the course of mounting it in said
casing.
7~
Owing to this construction the deformable
separator is free of substantial compression between the
rounded end of the supporting member and the casing,
that is, where traction and flexure forces are exerted in
operation. The deformable separator is thus protected from
fatigue which would otherwise be detrimental to its secure-
ment and service life. The rounded end of the supporting
member, which i5 preferably rolled, also protects the
deformable separator from tearing in the course of de-
formation and flexure.
The hooklike portion accommodates the bead and owing
to its considerable depth permits a thickened bead to be
used. During assembly the bead is compressed and bead
material is squeezed upwardly and flows into the wedge-shaped
space between the connecting zone and the casing, thereby
compressing the bead enclosed in the hooklike portion so as
to provide optimal securement.
The wedge-shaped space is sufficiently dimensioned so
that bead material may be amply accommodated without a risk
of shearing the deformable separator during assembly.
37 ~
Another feature or this arrangement i~ the pro~i~lon
Or a fluidtight seal between the annular æupporting means and
the casing to hermetically lsolate the flula chamber~ from each
other so that the mean~ for securing the annular supportlng
member to the casing need not ln~ure fluid tightne~æ.
Preferably the securing means ~or the supporting member
are bonding means, e.g. spot welds, a continuous weld or adhesive.
It is not necessary to insure systematlc inspection of the
contlnuity Or the welds or adhesive since the sealing function i8
perrormed by c4~pression of the bead in the wedge shaped space
the securing mean~ functioning merely to prevent axial shifting
Or the supporting member.
According to other features the hookllke portion has
slightly incllned rlank~ or opposed slope, a ~irst inclined
flank ad~oinlng the rounded end belng substantially perpendi-
cular to the centerline o~ the wall of the separator in lts
mean posltlon between lts rest posltion and its distended
position agaln~t the internal wall or the casing. The second
lnclined flank or the hookl~ne portion ad~oining the substan-
tlally cyllndrical portlon of the supporting member make~ an
angle with respect to a plane perpendicular to the axi~ Or
the vessel which i~ greater than the angle which the ~irst
inclined rlank makes with its plane~
Thus, preferably, the ~irst lnclined flank of the
hooklike portlon iB of flattened fru~toconical configuratlon.
According to still another preferred feature o~ the
present invention the radial extent o~ the first n ank is greater
than the distance between the radially outermost surface on the
rolled portion and the internal wall o~ the casing, whereby
the fir3t flank constltutes a retaining shoulder for the bead.
Owing to thls arrangement an excellent securement of
the separator is achleved sinre the first lncllned flank
pro~ideR a retaining shoulder substantlally perpendicular to
the ~ine along whlch traction forces are exerted on the
separator and in addltlon it asslsts the squeezing or flow of
excess bead material towar~s the wedge-shaped space durlng
mountlng, thanks to the more appreclable slope of the second
lnclined flank of the hooklike portion. In other words, the
rirst lncllned flank forms a bead retalnlng shoulder and the
second lnclined flank forms a slldeway for orlenting the
movement of excesR bead material towards the wedge-shaped
space.
Embodlments of pressure vessels according to the ln-
Yention are descrlbed hereinafter, by way o~ example, with
reierence to the accompanying drawings.
Brie~ Descri~tlon or the Drawings
Flgure 1 18 a longitudinal sectional view of a pressure
vessel embodylng the present inventlon ;
Figure 2 15 a fragmentary view on an enlarged scale
showlng the securement o~ the separator bead to the supportlng
member in the mounted pos~tlon ;
Figures3-6 show the several successive stages of the
mounting Or the separator in the caslng ;
Figures 7 and 8 show modi~led embodlments in whlch the
bonding means are spot welds and adhesive, respectively, and
Figure 9 ls a fragmentary Ylew of a modified embodiment
in which the rolled end of the annular supportlng member 18
a toroidal member dlstinct rrom the rest o~ the æupportlng
member.
Detailed Descriptlon Or the Preferred_Embodiment
Reierence will ~lrst be had to Flgures 1-6 wh~ch il-
lustrate by way of nonlimiting e~ample, an oil-gas type pressure
ves~el. m e pressure ~essel comprises a casing 10 of rigid
material, ~uch as steel, capable of withstanding the pres3ures
to which the pressure vessel ~ill be sub~ected ln use~
The caslng 10 comprlses a gererally cylindrical body
11 wlth closed ends 12 and 13. The closed end 12 has a fluid
port 14, for example an oil port, adapted to be connected to a
fluid coupler (not shown). The other closed end 13 has a fluid
port 15 for example a gas port, in whlch ls mounted a gas
charglng valve 16. Port~ 14 and 15 are ln axial allgnment.
~ore speci~icallg, the casing 10 comprlses flrst and
second opposed shell member~ lOA and lOB. The first shell
member~lnclu~es the closed end 12 and a long section llA of the
cyllndrlcal body 11. The sectlon llA ~as a sharp annular beveled
llp 27. The second shell member lOB lncludes the closed end 13
and a short sectlon llB of the cyllndrical body 11. The section
llB ha~ a sharp annular beveled lip 28 sllghtly spaced from the
be~eled llp 27 of the first section llA.
m e two shell members lOA and lOB are ~xed to each
other by an annular weld ~9 whlch extend~ inside the annular V-
shape~ notch deflned by the be~eled llps 27 and 28 Or sections
llA and llB.
A deformable separator 17 is p~sitioned inside caslng
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10~ the separator 17 being an elongate bladder of rubber or
similar material havlng comparable characteristics. The
bladder or separator 17 ls interposed between the ports 14
and 15 to define two varlable volume fluid chambers, l.e. a liquid
chamber l9 and a ga8 cha~ber 20.
The deformable bladder or separator 17 has at itB
lower end 21 a valve member 22 whlch cooperates with a valve
seat 23 deflned around l~quid port 14. The val~e member 22
preierably compri3es a cast steel or aluminlum dlsc at the
lower end ~l of the bladder or separator 17.
The bladder or separator 17 has a generally conlcal
sldewall 24 ilaring from the lower end 21 to a mouth 25 along
whlch i8 an annular bead. m e outer diameter of the mouth 25 is
substantlally equal to the internal dlameter of the caslng
10. The bead 25 ls attached to an annular supporting member 26
Or thin-walled or sheet material con truction, e,g. steel or
s~nthetic pl~stic material, mounted inwardly ad~acent the
cylindrical body ll. In the embodiment or Figures 1-6 the
thicknese of the supporting member 26 is less than hali the
thicknes~ or the caslng ll and may, ~or example, be one
quarter or one iiith or this thlckness.
Such a pressure vessel operates in a manner known per
se, as follows:
The port 14 i~ connected to a hydraul~c unl~ and gas
e.g. nitrogen, i8 supplied under pressure through valve 16
into chamber 20 untll the deiormable separator becomes dis-
tended and bears again~t the internal wall oi casing 10.
A stop cock (not shown) ls interposed between port 14 and the
hydraulic unit and when it is in open position the pressurized
liquid, e.g~ oil or water admitted through port 14 intO chamber
19 acts again~t separ~tor 17 to compress the gas ln chamber 20
causing the Yolume in chamber 20 to be reduced and llquid to
enter chamber 19. m e pressure vessel 1~ then in operative
condition. Oil contained in chamber 19 is, if necessary, con-
Yeyed to the hydraulic unlt by means of the pressu~ in the gas
chamber 20 actlng against the separator. When this happens,
the chamber 19 empties and lf lt ls completely emptied the
val~e member 22 beare æealingly agalnst valve seat 23 to close
off port 14.
The annular supporting member 26 i8 ~ixed, for in-
~tance~ by a weld 30 along the inner wall of shell member lOA,
sllghtly axially spaced from beveled lip 27.
The annular ~upportlng member 26 Or sheet material
has a ~ubstantially cylindrlcal portlon 31 the free end of which
i8 welded at 30, followed by a rillet or radiused connecting
zone 32 deflnlng a wedge-shaped annular space C with the inner
wall of the casing 11, then a hookllke p~rt1on 33 and flnally
a rounded or preferably rolled end portion 34.
AR indicated above the annular supporting member 26
which is of relat~vely rlgid material, such as steel or syn-
thetic plastic material, ls slightly flexible owing to its
unstiffened thin-walled construction along its cylindrical
portion 31, whereas its rolled portions 33 and 34 which are
7 ~
profiled are practically rigid. Alternatively, the cyllndrical
part 31 may be ~llghtly ~rustoconlcal before mountlng suppor-
tlng member 26 incasing 10 50 as to e~ert a slight prestress-
ing action at the time of as~embly.
The hookllke portion 33 comprises two slightly incllned
flanks o~ opposed slope, and flattened frustoconlcal con~igura-
tion, namely, a first lncllned M ank 35 adjoining rolled end 34
and a second lnclined flank 36 ad~oining connecting zone 32.
The lncllned flank 35 makes an angle A with a plane perpendic-
ular t~ the axl8 Or the caslng and the second inclined
flank 36 makes an angle B, greater than angle A, with such plane.
Preferably angle B is about t~ice aæ large a~ angle Ao
Further~ inclined flank 35 18 disposea perpendlcular
to the mean center llne posltlon D of the sldewall Or the
~eparator between the rest po81tlon (shown in phanto~ llnes
ln Figure 2) and a dlstended po#ltlon ln which the separator
bears againet the internal wall Or the casing 10.
Accordingly, the incllned flank 35 i8~ on the average,
dlsposed perpendicular to the llne along which the separator
i~ ten3ioned in operatlon and acts as a retalnlng shoulder ~or
bead 25, The other incllned flank 26 permlts sllding of the
bead material to orlent lts deformatlon lnto the wedge-space
space for accommodatlng the exce~s compressed bead m~terial.
The dlstance E between the rolled end portlon 34 of
the supporting member 26 and the lnternal wall of the cylln-
drlcal body 11 may be clearly viewed ln Figure 2 of the draw-
ingB. Thl6 dlstance ~ i8 substantially equal to the
-- 10 --
t
thickness o~ the bladder or separator 17 in it6 rest posltlon
so as to avoid any substantlal clamping or pinchlng ffl the
separator 17 at this point. me depth F of the hooklike portion
33 of the supporting member as measured from the internal wall
of the cylindrical body 11 ls selected to be equal to or
greater than two and one halr times the dlstance E. Preferably
the distance F ls between two and a half and three times the
dl~tance E.
me axlal height G of the hooklike portion 33 as
measured from the radlal outer limlt of the rolled edge 34
parallel to internal wall 11 i8 equal to or greaterthan the
dlfferencebet~een dlstances F and E.
Wlth further reference to Flgure 2, ~he annular
supporting member 18 shapea and dlmen~ioned to comply with
certain relationshlps to achie~e maxlmum holding of the bead
and thereby the entire separator.
In order to measure the varlous dimenslons or ~he
arrangement a Eieries Or llnes are drawn parallel to the mean
po~itlon D of the center llne Or the ~eparator sidewall.
These lines Ll, L2, L3, L4 and Ls are drawn a~ follows. 1ine L
is slmply the outer sur~ace of the separator 17 in its mean
position o~ the separator correspondlng to the mean positlon
D of the center line. 12 is drawn tangent to ~he radial
outermost surface on the rolled lower portlon 34. L3 i8
drawn parallel to center llne D at the Junctlon between the
beginnlng of the rolled lower end 34 and the lower flank 35
of the hooXlike portion. L4 ls drawn parallel to the center
llne D at the ~unction between the start of the 'ower flank 35
and the arcuate hooklike portlon 33. Flnally, L5 i8 drawn
parallel to the center line D from the radial innermost sur-
face of the hooklike portion 33. The distance between the lines
Ll and ~ i~ d~, the distance between L2 and ~ i8 d2, the
dlstance between L3 and L4 is d3, and the distance between
L4 and ~ 18 d4.
Accordlng to preferred embodimen~ of the invention
the distances dl, d2, d3 and d4 are chosen 80 that the follow-
relations a~e satlsfled :
~1) d2 ~ d
(2) d3 > d
(3) d4 ~ dl
Re~erence i6 next made to Figure 3 where the be~d 25
i8 illustrated in solid lines in itæ undeformed condition,
the internal wall of the cyllndrical body of the prssure
vesgel and the bead supporting member 26 being shown ln phan-
tom lines. It i8 seen that the contour of the bead 25 substan-
tlally mates with the inclined flanks 35 and 36 Or the hooklike
part 26 and has an extra thick zone S facing the inner wall 11
of the pres~ure vessel and a deep cut portion R facing t~
rolled lower end 34 of the supporting member. The additional
depth of deep cut portion R is substantially equal to the extra
thlckness of Zone S.
When assembling the pressure vessel, first, the bead
25 ls inserted in the correspondingly shaped hooklike port~on.
Then the ~ubassembly ~ade up of the supporting member 26 and
the bead 25 ~s introduced into the first shell member lOA ~the
beveled lip 27 of which is visible.] The engagement of the
subassembly past the rolled edge 34 has the combined effect
of the extra thick zone S compensating for the deep cut R and
squeezing the deformed bead m~terial 25A into the wedge-shaped
space C defined between the connec~ng zone 32 and the internal
wall of the casing 11 (~ee Figures 2 and 6). ~t should be
noted that the fillet or radiused zone 32 facllit~tes the
insertion of the cylindrical portion 31 into the Shell member lOA.
This deformation of the extra thick æone S of the
: bead 25 produce~ excellent holding of the bead 25 in the
~ hooklike portion of the supporting member without pinching
the separator or bladder 17 owing to the deep cut R facing
the lower rolled end. Fluidtightness between the chambers 19
and 20 is insured by the wedging of the deformad bead material
25A in the wedge-shaped space C.
It ~ill be appreciated that the flow of the bead
material into the free wedge-shaped space is favored by
frlction o.~ the casing 11 against the extra thick zone upon
assembly.
m e wedge-shaped space C is formed sufficiently large
for the bead material which M ows thereinto to be amply
accommodated without risking shearing of the separator or
bladder by the sharp edge of the beveled lip 27 when the
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7Y~
cylindrical portion 31 reaches the same.
To insert the subassembly comprised of the support-
ing member 26 and the bead 25 into the shell member 10A a
mandrel (not shown) is advantageously utilized. The mandrel
bears agiinst the upper end 31~ of the cylindrical portion 31
and abuts against beveled lip 27 o~ the shell member 10A when the
right predetermined position is attained, with the upper end 31t
longitudinally spaced inwardly from lip 27. When the subassembly
25-26 arrives in this position in the shell member 10A of the
casing, the upper end 31~ of the cylindrical portion 31 is then
welded to the internal wall of the casing at 30 with a continu-
ous weld as shown in Figures 1 and 2, or spot welds (as shown in
Figure 7). Then the s~ell member lOB is brought into position
on the shell member 10A and welded thereto as at 29.
It will be appreciated that the pressure vessel
according to the present invention enables mass production at
lower production costs with a considerable choice of casing and
supporting member materials whlle insuring the trouble-free
securement and long service life o~ the separator. It will be
noted that it is not necessary to machine grooves or slots in
the casing which are expensive and/or difficult operations
specially in synthetic materials and which weaken the casing and
thus require overdimensioning the casing thereby increasing their
weight and cost.
The slightly inclined first flank 35 of the flattened
~rustoconical configuration which is perpendicular to the mean
position of the center line o~ the separator or bladder 17
- 14 -
in the cour~e of operatlon, provides an extremely sturdy
securement of the bladder while the ~luidtightness i~
faultlessly insured bet~een chamber~ l9 and 20 by the en-
gagement oP the deformed bead material 25A wedged between
th~ connecting ~one 32 and the inner wall o~ the casing 11.
It 18 thus possible to avoid having to insure fluidtightness
by the Junction which secures the supporting member 26to the
casing. m e devlce of the in~entlon thus makes it possible
to spot weld the shell members together at spaced positions,
an operation which would not otherwise be permisslble.
According to a modifled embodiment shown in Figure 8,
which ~s generally similar to the prevlous embodiment, the
upper end of the cylindrical portion 31 of the supporting
member comprises an angled rim 37 whlch ~orms an annular recess
38 ~or a weld or a bead of adhesive 30. It should be noted
that the supporting member may, in the latter case, be rormed
Or synthetic material~ and there~ore admlts o~ the use of a
caslng ll o~ rein~orced plastlc material, Such a construction
i8 especlally interesting when the liquid to be used 18 hlghly
corrosive wlth respect to metals, when a coating is not deslr-
able on such a metal or where extremely high pressures are not to
be encountered.
In case the bonding means i5 an adhesive, the recess 38
makes it possible to apply the ~ame under excellent conditions
for drying and hardening, Such a recess or gutter 38 help
avoid dripping Or not yet dried adhesive into the bladder or
separator~
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~ n F~gure 8 the connecting zone 32' i8 frusto-
conical shape rather than radiused or filleted as in the
previous embodiments.
In Figure 9 instead of the rolled end portion of
the annular supporting member 40 belng fo~med in one piece
with the re~t of the supporting member 40 it is distinct
therefrom. The rolled lower end of the supporting member
- comprises a toroidal member 41 of preferably circular cross
section formed of yieldable material which is harder than
the bead ~ material. Accordlngly, when assembled, the bead
material tends to deform around the upper surface of the
toroidal member 41 as illustrated. Thus, unlike the previous
embodiments wherein the rolled end portlon depends from the
ad~oining lower or flrst flank, the toroidal member extends
upwardly relative to the surface of the long flank 42. The
toroidal member therefore tends to reinforce the holding capaci-
ty of the bead owlng to its convex upper surface compared to
prior art devices in which the surface of inclined portion
are generally concave, which concavity weakens the hold the
supporting member might otherwise provide. Finally, as
illustrated, lt is preferred to form the toroidal member 41
slightly offset on the free outer edge of the first flank 42
to prevent undue deformation of the bead for a given radius
of the rolled portion.
It will be recognized that variations of the
present pressure vessel may occur to those skilled in the
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art in light of the teachings hereofO Accordingly, the
invention is to be broadly construed wi~hin the scope
of the accompanying claims.
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