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Патент USA US2404924

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July 30; 1946-
Filed Jan. 29, 1.943
28 Flq‘a'
Cowmsus FE. SAccHam
Patented July 30, 1946
‘Columbus R. Sacchini, Euclid, Ohio, assignor to
The Marquette Metal Products Company,
Cleveland, Ohio, a corporation of Ohio
Application January 29, 1943, Serial No. 473,911
3 Claims.
(01. 277-45)
This invention vrelates to a safety stop valve
mechanism or ?uid fuse arranged to be inter
?ow .of liquid from the pump to the damaged
section of the'conduit and thereby prevents ex
cessive loss of liquid from the system. Inac
cordance with the illustrated embodiments, the
posed in a ?uid pressure conduit between a
source of ?uid supply and a ?uid operated trans»
lating device and operable for controlling auto
sliding valve member de?nes one wall of vair-an
nular restricted metering ‘orifice of uniform width
in response to therate of ?ow of the ?uid. More
but of decreasing diameter in the direction of
particularly'the invention relates to a ?uid fuse
?uid ?ow and the frictional force of the ?owing
having means operable in response to the rate‘oi
fluid on the valve member tends to move the
?ow of ?uid through the fuse to stop-the ?ow if 10 member to a'closed position against the bias of
the rate‘of flow increases to a‘valueiindicative
a calibrated spring. In event the rate of ?uid
of abnormal ‘condition.
?ow increases above a value predetermined by
In vaccordance with the illustrated vembodi
the sizeof'the orifice'and the calibration of the
ments of the invention herein disclosed, the
spring, the frictional force of the ?uid on the
means responsive to the rate of ?uid ?ow for
movable valve member moves to a closed position
effecting stoppage of '?uidv?ow comprises rela
stopping further flow of ?uid through the fuse.
matically the ?ow of ‘?uid through the conduit
'tively movable valve members which operate .to
If the increased rate of ?ow of the liquid is
a closed positionin- response to the;force of ?uid
friction on' a wall oftan annularrestricted meter
due to the breaking of ‘a conduit, the bro-ken
conduit may be repaired ‘or isolated by suitable
ing‘orifice having a, gradually varying diameter, 20 valves and :the fuse reset to open position for
ire. a" tapered . annular ori?ce.
resumption of'normal operation of the system
The invention .is ' particularly ssuitable for use
since the fuse prevents the loss of an excessive
with ‘hydraulic systems wherein ‘a liquid under
amount of liquid. ‘To reset the fuse it is merely
pressure ;from a suitable ?uid .pressure appa~
necessary to stop the pump or otherwise relieve
ratus such ;as ‘a pump or storage-tank is' utilized 25 the pressure‘against thefuse'forxan instant. An
to effect ‘operation of a‘ mechanism at a consid
auxiliary valve is vautomatically rendered op—
erable :distancerfromthe source of ‘ ?uid pressure.
erable upon apredeterminabledrop in this pres~
One application: ofithis'type of. hydraulic system
sure to prevent'?ow of the liquidpast the fuse
and one with vwhichithe present invention may
until pressure is againapplie'd, so that, if the
be .readilycombined togreataadvantageis in the 30 pressure against the fuse is reduced before the
operation of-variousxmovable devices on'aircraft
break is repaired, .no bleeding or additional loss
such, .for example, as the retractable landing
of the liquid results.
gear. :In aircraft hydraulic ‘systems asuitable
An object of the invention is to provide ‘an
liquidysuchas oil, under high ‘pressure is sup
improved automatic stop valve mechanism or
plied ‘from a motor 'or engine ‘driven pump
?uid fuse.
through conduits to servoemotors which operate
Another object is to provide a ?uid fuse re
the landing gear mechanism or 'otherdevices.
sponsive only to the rate of ?uid ?ow for stop
While the aircraft is in ?ight, one or moreof
ping the ?ow.
tne conduits may become broken, as by-a defect
A correlative object is to provide a ?uid fuse
or shell ?re, resulting ‘in a loss of much if not
responsive only to the‘rate of ?uid ?ow, which
all of the ?uid in the system.- This loss renders
fuse is adapted to be readily inserted in the usual
repairs during the ?ight impossible and,.since
?uid supply conduits of common hydraulic sys
many essential control and navigational devices
maytderive their motivating force from the same
Another object is to provide a ?uid fuse which
hydraulic system, is apt to result in loss of the
can bereset without dismantling or disturbing
the . adjustment.
‘Breaking or puncturing of a conduit in .such
A correlative object is to providea ?uid fuse
aircraft hydraulic systems immediately causes an
whichcan be reset automatically from a point
increase in the rate of ?ow ‘of the liquid therein,
and, if the‘?uid fuse ‘of the present invention is 50 remotefrom the fuse but without opening a free
?uid path through the fuse.
incorporated in the system between the pump and
‘A further correlative object is to provide a
the pointof'leakage, the increase in the rate of
?uid fuse which can be ‘reset by relieving the
flow causes an increase in ‘the force of ?uid fric
pressure against the fuse without necessitating
tion on-ia: sliding valve'memberiwhich thereupon
moves'to. a closed'p‘osition :and'stops any-further 55 an auxiliary valve orother ‘means outside of the
fuse to prevent ?ow of ?uid through the fuse
upon reduction of supply pressure.
Still another object is to provide a ?uid fuse
of the above indicated character which is small
and compact, of rugged construction, and com
simple to manufacture.
Fig. 4), that is, an ori?ce of uniform width but
of gradually decreasing diameter in the direction
of ?uid ?ow. The plunger 30 has a generally
cylindrical upstream stem portion 32 of reduced
diameter and provided with ?uid venting “?ats,”
said stem portion 32 being slidably received
within a complementary longitudinal bore 34 in
Another object is to provide a ?uid fuse oper
able to a closed position due to friction of ?uid
a cut-off valve plunger 35 (to be described later).
A cylindrical downstream stem portion 36 of the
prises a small number of parts each of which is
10 plunger 30 passes through a central opening in
at a tapered annular metering ori?ce.
an axially movable spring guide 39.
Yet another object is to provide a ?uid fuse
The spring guide 39 is slidably received within
having means for readily adjusting its sensitivity
the opening 2! downstream from the valve seat
without disturbing the setting of its operating
surface 29 and is of generally rectangular trans~
verse cross section. As indicated in Fig. 5 the
Other objects and advantages will become ap
parent from the following speci?cation, wherein
cross section of the guide 39 deviates from a true
rectangle in that the shorter sides are curved to
reference is made to the drawing in which
conform with the inner wall of the housing ID
Fig. l is a diagrammatic representation of a
to de?ne therewith a pair of circular segmental
hydraulic control system incorporating the auto
matic ?uid fuse of this invention; Fig. 2 is an ele 20 ori?ces 49. The guide 39 operatively abuts an
annular shoulder 4| on the valve plunger 39 pro
vational view of the automatic ?uid fuse; Fig. 3
vided by a portion 36' of increased diameter be
is a longitudinal sectional view of the fuse of Fig.
tween the stem portion 36 and the central por
2; Figs. 4, 5, 6 and 7 are sectional views taken
tion 30'.
generally along lines 4-4, 5—5, 6—6 and 'l—‘l,
The valve plunger 39 is normally biased to fully
respectively, of Fig. 3, and Fig. 8 is a fragmentary 25
open position by a helical spring 42 interposed
longitudinal sectional view showing a modi?ca
between the guide 39 and a spring support 44
press ?tted or otherwise secured ?xedly in the
Referring to the drawing, a unitary tubular
counterbored portion 24 of the opening 2| against
body or housing [9 of the hydraulic fuse ll of
this invention has (e. g.) a hexagonal portion l2 30 the shoulder 26. The support 44 has a transverse
cross section similar to that of the guide 39 as
intermediate 9, pair of externally threaded cylin
shown in Fig. 6 and de?nes with the inner wall
drical end portions l4 and [5 which are adapted
of the housing I0 a pair of circular segmental
to be screwed respectively into complementary
ori?ces 45. The ends of the spring 42 rest re
tube couplings on spaced ends of suitable ?uid
supply conduits I6 as shown more or less dia 35 spectively in shouldered recesses provided by op
posing tubular end portions 39’ and 44' of the
grammatically in Fig. 1. The ?uid in the con
duits I6 normally ?ows freely through the fuses
guide 39 and the support 44, respectively which
end portions may be of circular section.
II from a pump !8 arranged to force ?uid from
The stem portion 36 of the valve plunger 39
a reservoir l9 to a plurality of hydraulic servo
motors 20 such as commonly used to actuate var 40 extends slidably through the central opening in
the support 44 and is threaded at its outer end to
ious subservient devices, e. g. retractable landing
receive an adjusting nut 46 which may be secured
gear mechanisms. Upon the occurrence of an
in adjusted position as by spot-Welding a washer
abnormal rate of ?uid ?ow through one of the
48 to the stem portion 36. The adjusted position
fuses H such as would occur upon the breaking
of the nut 46 determines the size of ori?ce 33
of a conduit beyond the fuse, the fuse operates
when the plunger 30 is in its normal open posi
automatically to stop further ?uid ?ow and con
sequent loss of ?uid. On military combat air
tion and, as will be described hereinafter, thus
determines the critical rate of ?uid ?ow which
craft, because of the great likelihood of enemy
causes the plunger 30 to move to its closed posi
?re severing the conduits I6 it is desirable that
the fuses H be spaced at short intervals to pro 50 tion. The rate of ?uid flow for which the ad
tect as completely as possible the ?uid system
justment is made can be stamped on the housing
from loss of ?uid. The protection afforded by
In to indicate the protective point of the fuse l i.
the fuses H when so arranged permits repairs to
The cut-off valve plunger 35 has a central
be made during ?ights, prevents total disability
frusto-conical portion 49 intermediate oppositely
of the hydraulic system by the breaking of a
extending stem portions 50 and 5| and the pe~
ripheral surface 52 thereof is arranged to seat
single conduit, and greatly reduces the ?re haz
ard which would result from leaking oil.
upon a complementary valve seat surface 54 pro
The tubular housing H] of the fuse H has its
vided at the inner end of a tubular cut-off valve
central opening 2| (Fig. 3) counterbored at both
seat member 55 slidably received Within the
1 ends as indicated at 22 and 24 to provide annular
counterbored portion 22 of the opening 2| against
shoulders 25 and 26, respectively. An inward pe
the shoulder 25. The valve seat member 55 is
ripheral projection 28 narrows the opening 2i in
suitably retained in position as by spinning over
termediate the ends of the housing I 9 and de?nes
the tapered end of the threaded portion [4 of the
a frusto-conical Valve seat surface 29 which
housing [0 as indicated at 56. The downstream
tapers inwardly or converges in the direction ‘of
stem portion 50 is a cylinder of lesser diameter
?uid ?ow indicated by the arrows. A valve
than the base of the frusto-conical portion 49 to
plunger 39 is provided at an enlarged central por
it is joined by a cylindrical portion 50’ of
tion 30' with a peripheral face portion 3| com
intermediate diameter and has the longitudinal
plementary to and adapted to seat upon the valve
bore 34 in which the stem portion 32 of the valve
seat surface 29 when the plunger 30 is moved to
plunger 39 is slidably received. The upstream
the right from the position in which shown.
stem portion 5| (see Fig. 7) has a cross section
When the plunger 39 is in its normal or open
similar to that of the spring guide 39 and is slid-V
position, shown in the drawing, the valve seat
ably received within the circular opening in the
surface 29 and the face portion 3| are spaced
valve seat member 55 and de?nes with the walls
apart to de?ne a tapered annular ori?ce 33 (see;
thereof a :pair :of :circular .isegmental orifices ‘58,
Fig.‘ '7.
A ihelical sspring $59 which is weaker than
the spring ‘4-2 :is ‘interposed between Ithe 'valve
rplungers :30 and 35 :and "normally biases Ithe
valve'vplunger 35 tozits ‘fully :closed position on
.the’valveseat member 555 as shown in vFig. 3.
.Theiends of =the.'spring >159 rest respectively in
annular shouldered recessesprovided :by the por
‘tapered gori?ce :33. If the pump .l.8 QShOUld :stop
‘The ‘operation of the ‘fluid ‘fuse will ‘be ex
be done-after the broken conduit ‘has‘been =re
for any reason, :the :trappedifluid pamrot :escape
since :the :valve :plunger .35 returns :to :its closed
vposition, :the spring 59 having-a su?icient'bias
.ing force to iclose ivthe ‘plunger 35 :against :the
hydraulic'headexisting‘when the pump l8iiS not
operating. Closure ‘of the valve plunger 135 :of
course permits opening of the ori?ce"*33 due "to
the'bias' ofithe spring '42 on'theplungeris?. Thus
tion 5.0’10'f the‘plunger 35~and~a similar portion ‘ the fuse l 1 maybe reset to normal position, after
it has operated, merely by the pilot o‘flthe plane
F32’ :between the stem portion ‘32 and 1the portion
stopping the ‘pump 'for'an instant, which may
530' ofthe valve plunger' 30.
plained by-considering-that a single'fuse II is
inserted in the conduits‘ 16 "between the vpump _;
1| 8 and the “hydraulic-cylinders "'29, 'l the operation
paired or' by-passed.
‘ It is thus seen that ‘no-manipulation-or 'dis
mantling of the fuse aH is-required"for resetting,
v'o‘f asystem lwith'moreithan one ‘fuse as illus
this operation'being performed by hydraulically
tratedin‘Fig. l'being apparent therefrom. ‘Fluid
pressuredue "to operation of vthe pump :exerted
acting means under the control of the ‘pilot.
on itheIfrusto-conical'portion '4-9 of the cut-off
'valvelplunger 35 causes the ‘plunger 35 to move
away from‘itsseate'd position on the seat mem
‘ber 5'55 against the bias of the spring 5-9 and
thereby-e?ec‘ts opening of an annular ori?ce be
tween tlie complementary surfaces 52 and 54.
‘FIuid‘is now free to flow from the pump l8
through the fuse I! to effect operation of any or
all of ethe-servo-motors ~20. ‘It should be noted
‘The fuse ‘H may-therefore be mounted'in-"any
position in "the system whether readily acces
sible or'not. Besides permitting quick re-usepf
the hydraulicsystem after-the breaking of'a'con
duit while still-in flight, the semi-automaticre
setting feature is extremely valuable ‘also ‘because
of the'possi-bility ‘of surges‘in :the system ‘:being
sufficiently :great 'to cause operation'of the fuse.
In such .event all ‘that need be ‘done isto *stop
or short circuit theipump ‘for an instant in order
'from'the drawing'that with the" plunger '35-0pen
and-the-plunger 230 in-its normal position are
'stricted fbut =unobstructed ?uid path exists
through the‘fuse I l '.
Due to the inertia of the moving parts of the
.to return the ‘fuse ,to its normal positionand
then to restart or recondition the pump and the
servo-motors 20 and-the-resistance of the mech
anisms operated thereby, the rate of flow of the ‘
?uid through the fuse II normally does not ex
factured by varying ‘the degree of‘taperofthe
‘complementary surfaces '29 and "3|. ‘By making
system is again ready foruse.
‘Fuses having various degrees .of sensitivity,
that is various speeds of response, 'can'be manu
the taper of these surfaces less gradual, the fuse
becomes more sensitive in its operation. For
use in systems subject to repeated surges, a fuse
broken or punctured conduit between the fuse
of low sensitivity is apt to be most suitable since
II and the servo-motors, however, the rate of
flow of ?uid through the fuse ll quickly exceeds 40 if the surge is not very great and ends before
the ori?ce 33 is closed resetting of the fuse is
the predetermined value. When the ?uid is ?ow
not required. The sensitivity of the fuse is also
ing through the tapered annular ori?ce 33 at a
dependent upon the rate of the springs 42 and
rate in excess of the predetermined Value, the
59: and thus a wide range of sensitivities is pos
frictional force resulting from the action of the
ceed a predetermined value.
In event of a
?uid on the conical surface 3| causes the valve ‘ ‘7 sible by various combinations of taper and spring
plunger 30 to move toward its closed position
against the bias of the spring 42. As the plunger
The rates of the springs 42 and 55 depend upon
the design of the respective? springs and thus
30 moves, the ori?ce 33 becomes smaller and the
fuses of various sensitivities‘ can be manufac
?uid friction correspondingly increases resulting
tured by choosing certain springs during assem
in further movement of the plunger 35 and
bly. Another method of predetermining sensi
eventual seating of the surface 3| on the surface
tivity during manufacture of the fuse is shown
39 with a snap action, closing the ori?ce 33 and
by the modi?ed construction of Fig. 8.
trapping all of the ?uid in the system between
In Fig. 8, wherein similar parts are referred to
the pump I8 and the fuse l i. As thus described,
the fuse H has performed its main function of 55 by the same numerals as in the other ?gures plus
190, the counterbored portion I24 of the opening
preventing excessive ?uid loss due to a broken
£21 in the housing H5! is threaded and receives
conduit. When two or more fuses are connected
a complementary threaded spring support I44.
in series in a conduit system, the sensitivity or
The threaded connection between the housing I I0
setting of the fuses may be chosen so that the
fuse closest to the broken conduit operates ?rst 00 and support Md provides a means for adjusting
the sensitivity of the fuse by varying the length
so that if possible a part only of the system may
and consequently the rate of the spring I42.
be shut off, much in the manner of overload
When the support M4 is in the proper position
protection commonly applied to electrical power
for the desired sensitivity, it may be suitably se
distribution systems.
After the valve plunger 30 has moved to its 65 cured against further rotation as by a locking
pin 65 inserted in a hole drilled through the coni
closed position, the ?uid trapped between the
cal end of the portion H5 and into the support
pump l8 and the fuse H is under high pressure
fill. If it should be desirable to provide for
and, so long as the pump [8 continues to oper—
ate, pressure on the portion 38' maintains the
plunger 33 in its closed position. Extensive ex
periments have shown that whereas the plunger
30 is retained in closed position due to ?uid
pressure, ?uid pressure has no effect on its closing
operation which is entirely dependent upon the
friction force of the ?uid passing through the 75
variation of the sensitivity of the fuse after manu
f acture, a suitable set screw may replace the look
ing pin 65 and be arranged for screwing through
a tapped opening in the portion H5 against the
support I44.
I claim:
1. In a ?uid fuse, a casing having a passage
extending therethrough from end to end, a valve
means comprising a frusto-conical valve seat sur
face in said passage intermediate its ends and
a valve plunger slidably mounted in said passage
for axial movement with respect to said casing,
said plunger having a frusto-conical face portion
complementary to and adapted to seat upon said
seat surface and when so seated closing the pas
sage through said casing, biasing means normally
biasing said face portion and said valve seat sur
face apart to de?ne a tapered annular ori?ce,
the biasing force of said biasing means being less
than the axial frictional force of said ?uid on
said face portion when ?uid ?ows at a rate above
a predetermined value through said tapered ori
?ce, whereby said ori?ce is closed by said fluid
friction when the rate of ?ow of ?uid through
means normally urging said face portion and said
valve seat apart to de?ne an annular ori?ce ta
pered in the direction of ?uid ?ow, the biasing
force of said biasing means being less than the
axial frictional. force of said ?uid on said face
portion when ?uid ?ows at a rate above a pre
determined value through said tapered ori?ce,
whereby said ori?ce is closed by said ?uid friction
when the rate of ?ow of ?uid exceeds said pre
determined value, and a second valve means con
tained within said passage in series with said
?rst valve means between said ?rst valve means
and said inlet, said second valve means being
normally biased to a closed position and movable
to an open position in response to ?uid pressure.
3. A ?uid fuse comprising a casing having a
passage extending therethrough from inlet to
outlet, a frusto-conical valve seat forming part
said ori?ce exceeds said predetermined value, and
of said passage located between said inlet and
a second valve means contained within said pas
sage in series with said ?rst mentioned valve 20 outlet and converging toward the outlet, a plung
er guided for axial movement in the passage
means, said second valve means being normally
and having a frusto-conical head portion com
biased to a closed position and movable to an
plementary to said seat and surrounded thereby
open position in response to ?uid pressure.
normally spaced suf?ciently near the seat so that
2. In a ?uid fuse, a casing having a passage
the head tends, to be moved against the seat by
extending therethrough from end to end, one
friction of ?uid en route through the passage to
end being an inlet and the other end being an
ward the outlet, a pair of springs of different
outlet for ?uid ?owing through said passage, a
valve means comprising a frusto-conical valve
strength acting oppositely axially on the plunger,
seat surface in said passage intermediate its ends
and a valve vplunger slidably mounted in said
passage for axial movement with respect to said
casing, said plunger having a frusto-conical face
portion complementary to and adapted to seat on
the stronger of . the springs normally maintaining
said valve seat surface and when so seated clos
ing the passage through said casing, biasing
the frusto-conical surfaces spaced apart as stated,
and a valve in the inlet normally closed by the
weaker of the two springs and opened by ?uid
pressure at the‘mlet.
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