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Патент USA US2411315

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Nov. 19, 1946.
B, 'N_ ASHTON
2,411,315
METAL BELLOWS ACCUMULATOR
Filed Oct. 27, 1944
10
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19
12a
INVENTOR.
‘ 5:40AM” Alla/717v”
AfJUfF/VEKY’
Patented Nov. 19, n 1946
2,411,315
‘UNITED STATES PATENT OFFICE
2,411,315
METAL BELLOWS ACCUMULATOR
Benjamin N. Ashton, Kingston,\N. Y., assignor to
Electrol Incorporated,
poration of Delaware Kingston, N. Y., a cor
Application October 27, 1944, Serial No. 560,702
5 Claims. (01. 138—31)
This invention relates to accumulators for use
in hydraulic systems for-aircraft, for example,
which are“ utilized to control the operation of
retractable landing gears, wing ?aps, and the
like.
The accumulators heretofore provided usually
consist of a tank or receptacle capable of with
standing high pressures and which is provided
with a resilient diaphragm usually formed of rub
A further object of the invention is to provide
a metallic bellows type of accumulator for a hy
draulic pressure system in which the bellows is
protected against damage by means of liquid
trapped in the accumulator, when the pressure of
the gas and the hydraulic ?uid are unequal.
Other objects of the invention will become ap
parent from the following description of a typical
form of accumulator embodying the present in_
berized fabric dividing the receptacle into two 10
vention.
Accumulators of the type embodying the pres
ent invention may suitably consist of a hollow cy
sure of‘ the ‘hydraulic ?uid in the other chamber
chambers. A gas under pressure is supplied to
one of the chambers in order to oppose the pres
whch is connected to the hydraulic system. -
Inasmuch as the pressure in the hydraulic sys
tem ?uctuates, the capacity of the hydraulic ?uid
receiving chamber of the accumulator varies in
order to store excess liquid and to accumulate
pressure liquid which may be utilized to operate
the mechanical elements associated with the sys
tem and to smooth the ?uctuations of pressure
inthe system.
lindrical receptacle provided with a metallic bel
lows, such as a “Sylphon” bellows, having a free
end provided with a valve member that cooperates
with a valve seat in the end of the cylinder and
a valve seat spaced axially from the end of the
cylinder. The valve member is adapted to en
gage the valve seat at the end of the cylinder
upon expansion of, the bellows to a predeter
mined point, whereby liquid‘ will be trapped in
>
the space between the bellows and the rece'p- .
tacle, thereby preventing bursting of the bellows H
When the volume of the ?uid in the accumu
lator varies during the operation of the hydraulic
system, the diaphragm is ?exed back and’ forth
with the result that it ultimately is weakened and
a leak may develop which permits mixing of the
compressed gas with the liquid. Also, if the gas
pressure or liquid pressure in the system drops,
under the gas pressure therein.
The valve member on the bellows also is
adapted to engage the other valve seat to limit
the extent of the compression of the bellows and
also to trap liquid around the bellows, so that
the bellows will not ‘collapse upon decrease of the
the diaphragm may be expanded to such an ex
tent that‘it is ruptured or damaged.
It has been proposed heretofore to provide
valves in the accumulators that will prevent the
complete escape of liquid from the accumulator,
air pressure therein or the generation of an ex
a’ cessively high ?uid pressure in the hydraulic sys
tem.
so that a bellows or a diaphragm will be sup- r.
ported by trapped liquid even if the liquid pres
sure in the system should drop to zero.
Accumulators of the type embodying the pres
ent invention are protected against damage vby
variations in the pressures of the‘ pressure gas
and the hydraulic ?uid, and thus, if desired, the
accumulator can be preloaded with hydraulic
?uid when placing it into operation without the
All of the above described accumulators have
the disadvantage of being dii?cult to pre-load
either with hydraulic ?uid or with gas under 40 bellows being damaged. Thereafter, gas under
pressure can be introduced in order to charge the
system to the desired operating pressure. Simi
pressure without damage to the accumulator, for
the reason that it is di?icult to charge both cham
bers of the accumulators simultaneously to equal
pressure during/the installation of the accumu
lator.
larly, the accumulator may be charged with‘ gas
under pressure before‘ it has been brought up to
the operating pressure of the hydraulic system
without exploding or rupturing the bellows,
-
An object of the invention is to provide an
accumulator that can be‘ preloaded with hydraulic
For a better understanding of the present in
vention, reference may be had ‘0, the accompanying drawing in which the single figure is: a view
?uid without danger of damaging the accumu
lator.
.
-
Another object of the invention is to provide
an accumulator having a ?exible metallic bel
lows and safety control valves which prevent
damage to the bellows by variations in pressure
of the hydraulic ?uid and the gas in the accu
mulator.
I
)
50
in vertical section of a typical form of accumu
lator embodying the present invention.
The form of accumulator chosen for purposes
illustration includes a cylinder I0 formed of a
55
generally, cylindrical and cup-shaped receptacle
member I I which receives telescopically‘, and is
threaded onto, a second generally cup-shaped'cy
3,411,315
susceptible to considerable modification and that
lindrical element l2. The edge of the member ll
the type and’ shape oi the bellows, as well as the
construction or the tank, can be varied widely
abuts against a shoulder In on the lower cylinder
memberv l2 when the two elements H and I2 are
without departing from the invention. There
connected. JLeakage between the elements It and
II is prevented by means 01- a suitable gasket or
fore, the form of the invention described above
sealing ring it. The member II ls provided with
a port I; therethrough that is threaded internal
ly in order to permit it to be coupled with a hy
limiting the scope of the following claims.
should be considered as illustrative and not as
I claim:
7
.
1. An accumulator for hydraulic systems com
, draulic system, not shown.
The cylindrical cup-shaped element I2 is also 10 prising a hollow, tubular cylinder having closure
provided wlth‘a central opening I! for receiving -
an annular bushing 18 which projects outwardly
from a disk-like ?anged base is secured to the
lower end 01’ a metallic bellows IS. _The bellows
members at its opposite ends, means in one oi.’
said closure members for connecting said cylim
der to a hydraulic system; an expansible and \
compressible metallic bellows having one end
I! may be 01' the “Sylphon” type or any other 15 secured to the other closure member and hav
ing a ‘free end expansible toward said one of
equivalent contractable and expansible metallic.
.said closure members, means for introducing a
bellows construction. The bushing l6 may be
gas into the interior ‘of said bellows, a valve seat
threaded into the opening I! and is provided with
\ an annular groove Ida for receiving a rubbery
sealingring 20.
An air check valve‘2 I. is mounted in the bush
member insaid cylinder disposed outwardly of
20 said bellows, and a valve member 'on said free
ing ii to permit gas under pressure to be intro‘- -
end‘ of said bellows engageable with said valve
seat member upon compression of said bellows
to trap hydraulic ?uid between said cylinder and
duced into the interior of the bellows IS.
said bellows and prevent collapsev of said bellows. '
The upper end of the bellows I9 is provided with
2. An accumulator for hydraulic systems com
a disk-like plate '22 which has an annular groove 25
prising a hollow, tubular cylinder having closure
23 in a raised or thickened portion 22a of the
members at its opposite ends, means in‘ one of
plate for receiving a rubbery toroidal ring 24 in,
said closure members for connecting said cylin
its upper surface. The ring 24 cooperates with
der to a hydraulic system, an expansible and
the inner end lie of the receptacle member II
to form a check valve for preventing escape oi’ 30 compressible metallic bellows having one end se
cured to the other closure member and having
liquid from between the bellows l9 and the cyl
a free end expansible toward said one closure
inder l?‘through‘ the port ll.
v
member, means for introducing a. gas into the
. interior ‘of said bellows, cooperating valve and
valve seat formed by the upper edge l2b of the 35 valve seat members carried by, said one closure ‘
The plate 22 projects laterally beyond the pe
' riphery oi! the bellows l9 and cooperates with a
member l2 and.a_ toroidal, rubbery sealing ring
25 ‘mounted-‘in a groove or recess .l2c therein.
‘When the bellows I9 is compressed by an increase
member and said ‘free end of said bellows, said
\ valve and valve seat members being engageable
‘upon expansion of said bellows for trapping hy
draulic ?uid between said cylinder and said bel
- in pressure in the hydraulic system, the edge of
- the plate member22 engages the rubbery ring 40 lowsvto prevent overexpansion of said bellows, a
second valve seat member in said cylinder dis; '
25 and the valve seat 12b, thereby preventing the
pressure of the liquid in the space between the
bellows VI! and the member l2 from exceeding the
pressure within the bellows l9.
,
posed outwardly .of said bellows, and a valve
member on said free end of said bellows engage
. able with said second valve seat member upon
In operation, the accumulator may be connect-, 45 compression of said bellows to trap hydraulic
?uid between said cylinder and said bellows and
ed to the hydraulic system through the port ll,
prevent collapse of said bellows.
‘ and the pressure in the system may be built up,
3. An accumulator for hydraulic systems com
thereby compressing the bellows I9 until the plate
prising a hollow, tubular cylinder, having closure
. member 22 engages the seat I21: and the rubbery
members at opposite ends, a hollow expansible
ring 25. Under these conditions, the exterior of
and contractible metallic bellows secured in one
the bellows will not be subjected to any greater
’ pressure than that required to compress it to
such a condition that the plate 22 engages the \
valve seat Hi), and accordingly, the bellows will
not be damaged. After this condition has been
attained, gas under pressure may be introduced
_ through the air check valve 2l'ulnto the bellows
end of said cylinder and having a free end mov
able toward one of said‘closure members upon
expansion of said bellows, means forming a port
in said one closure member for connection with
said hydraulic system, an annular valve seat
encircling said port, a valve seat member within
until a desired‘ gas pressure is provided within v said cylinder spaced axially from said one closure
and disposed radially outward of said bellows,
the bellows. If this gas pressure materially ex
,_ ceeds the pressure in the hydraulic system, the 60 and a valve member carried by said free endv
plate member 22 will beforced against the end‘
lie of thecylinder ID, with the result that liquid
is trapped between the bellows I9 and the wall of
. the cylinder I0,-and the pressure of the gas is
resisted by the trapped liquid.
’
From the preceding description, it will be ap
parent that a metal bellows accumulator has
of said bellows and engageable. with said valve
seats to trap hydraulic ?uid between said bellows
and said cylinder upon contraction and expan
sion of said bellows to predetermined limits.
4. An accumulator forhydraulic systems com
prising a hollow, tubular cylinder, having closure
members at opposite ends, a hollow expansible
and‘ oontractible metallic bellows secured in one
been provided in which the bellows will not be
damaged by wide pressure differentials on its ~l end of said cylinder and having a free end mov
opposite sides and in which the bellows is pro
tected against damage ‘during the period when it ,
is being assembled in the hydraulic system and
charged or preloaded to its desired operating pres
sure.
able toward one of said closure members upon
expansion of said bellows, means forming a port
in said one closure for connection with said
hydraulic system, a plate member on the free
end of said bellows, an annular groove in said
It will be understood that the accumulator is 75 plate member substantially concentric with said
2,411,315
,
a
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port and of greater diameter than said port, a
rubbery, toroidal ring in and projecting from said
groove, and movable with said plate member into
and out of engagement with said one closure, _
a member within said cylinder providing an an
6
members at its opposite ends, a hollow, expansible
and contractible metallic bellows, having one end -
secured adjacent one end of said cylinder and
its opposite end free to‘ expand' toward and con
tract away froni the end closure at the opposite
nular vvalve seat spaced axially from said one
end of said cylinder, means including‘ a port in
end closure and disposed outwardly of said bel
the last-mentioned closure for connecting the
lows, an annular groove in said annular valve
cylinder to a hydraulic system, a valve seat in
seat, a second rubbery, toroidal ring in and pro
said cylinder disposed outwardly of said bellows,
jecting from said groove, said plate member be 10 a groove in said valve seat, a rubbery sealing
ing engageable with said end closure and said
member in and projecting slightly :from said
valve seat and said second ring to trap hydraulic
groove, and a valve member on said free end of
?uid between said bellows and said cylinder upon
said bellows engageable with said sealing member
contraction and expansion of said bellows to
and said valve seat upon contraction of said
predetermined limits.
15 bellows.
5. An accumulator for hydraulic systems com
BENJAMIN N. ASHTON.
prising a hollow, tubular cylinder having closure
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