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Патент USA US2412277

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Dec. 10, 1946. I -
c. c. s..|_E CLAfR
Filed May 28; 1945
s ‘Sheets-Sheet - 1
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‘ G‘ 6. 6%;
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A ttorneys.
Dec. 10,1946.
0. c. 5. LE CLA?lBL r
Filed May 28, .1943
5 Sheets-Sheejt 2
v. .
Dec. 10, 1946.
c. (3.5. LE ICLYAIR
. ‘2,412,277
.Filed May 28, 194.3
‘ s Sheets-Sheet 3
, (821,11
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Patented Dec. 10, 1946
, 2,412,277
Camille Clare Sprankling Le Clair,
Acton,‘ London, England
' Application .May 28, 1943, SerialNo. 488,935
In Great Britain June 5, 1942
4 Claims;
plicable to the damping. of the movementsof' a, '
This, invention relates. to. hydraulic. damping
devices, of the general'type comprising two tele
scopically arranged members, one,. or both, of.
member oscillatably, mounted. upon. the fuselage.
of an aircraft and towhichone endoflatow ropev
is secured, the object of‘ the dampingdevice being;
to ‘absorb, the inertia energy» transmitted‘ through
the, said member and. to. causevthelmemberito
which maybe connected to a member, ormem
bers, whose movements are to be damped, 'andla
piston which is adapted to displace-the liquid in
the circuitfromone side to theother of the piston.
Ar hydraulic damping, device. according terms
invention, comprises a main» or. operating; cylinder
which isadapted to be-operably connected to an
take up. new positions gradually» without shock,
andwithout surge. _
Brie?y, vthis construction. comprises two head
10 ers one of. which: is’ connected» to, an‘ oscillating\
member, the headers, being. arrangedlat, opposite
anchorage, or to the‘ member whose” movements.
areyto. be damped, a main or operating piston,
which is slidable withinthe cylinder and is adapt
ends of an operating ormainwcylinder in which.‘
is slidable an outer or. main. piston! connected to,
an outer. tube. fastened to. a: ?xed- anchorage ‘on,
ed to be operably connected to the saidmember
or said anchorage and-to displace-liquid from-‘one
the fuselage. Thew telescopic: movements. of, the’
cylinder and outer tube and, pistonpdueto the
oscillation of the said member, cause thelliquidl
in. the cylinder. to; berdisplaced, the liquid circuit
being. completed through a-transfer tube ‘and’.
thereof and which is so constructeduandarranged
thatthemagnitude of the damping. actionis'de 20 the. displacement ofl liquid from onersid'e. tovthe
other, of‘. the piston. being resisted by spring.
pendent primarily upon the resistance: offered
loaded Or inherently-resilientvalves asdescribed.
by said. means to. the flow of. liquid and .notupon
above,‘ said valves being,‘- arranged. adjacent tothe
the viscosity of theliquid.
sideof the'piston to'the opposite side; andwmeans
which is adapted to resist. the transfer of liquid.
from one side of the piston tothe. other side
It is. to be understood. that the‘
anchorage rte-t
opposite endsv oftheitransfertubep
ferredto above may. be a. fixed or movable an» 25
The said liquid-transfer resisting‘ means may
consist of a valvea-dapted to» open‘ and close‘an‘
ori?ce through. which the: displacement of- the
liquid from the operatingcylinder. takes place, the
changes upon the liquid.
rating that when the valve is on‘ its seat, little
or no load is applied by the spring, and when the
damping effect, is substantially proportional to
of'liquid through one or ‘more ori?ces.
As a modi?cation, use may/be'made of a disc
oscillatably mounted~ upon the fuselageof anair
craft and to. whicnone endjof‘ a glider tow rope.
valve is lifted to the fullextent the load appliedv _
the rapidity of displacement of the liquid or, in
other words, of the‘ piston. The e?ect of vis
cosity is therefore‘ substantially negligible‘. The
energy absorption is provided, by the work done
by the liquid in forcing itself past the valve
against the force of the controlling spring, this
being in contradistinction to known means where
in the energy absorption is due‘ to the viscous flow
One constructional: form of‘ the‘ invention,
adapted to’ damp‘ the movements of‘ ‘a member,
said valve being loaded by a spring of such. a
is such as to exert the maximum desiredresist
ance to the ?ow of liquid through the said ori
?ce. In this manner, the force opposing the
movement of the piston in its cylinder, i', e., the
Means, acting, as. a pressure accumulator, are
also provided for compensatingfor the di?ferene
tial displacement, of‘ the operating, piston- and
for putting. the liquidund'er‘initial pressure‘ and?
‘compensating for the. effect~ of“ temperature.
secured, is hereinafter described',,by_ .WayFof,
example,v with reference to the ‘accompanying
drawings, whereon:
Fig. 1- is a sectional elevation‘ of" the upper part
of'the device;
Fig.‘ 1A is a sectionalelevation of the bottom
part1 oith'e' device; and.
_ Fig; 2 is-anv outside elevation thereof;
Referring to the drawings‘:
The object of: the device is. to absorb the in,
ertia; energy transmitted‘ through. the said" mem
ber oscillatably mounted upon the fuselage and
to; cause the member to take upv new positions.
gradually andwithoutshock or surge.
The device comprises/an operating; cylinder I‘,
valve ?xed at the centre and free at thev edge, 50 on to‘ the‘ upper end of which is secureda tubular
upper header 2 ?tted‘ at the top with a. hollow
the said valve‘ having sui?cient inherent resil
cap 3- having‘ an apertured bottom, wall 4; ‘The
iency and resistance to perform‘the function re
quired without using a, separate spring.
The constructionallform‘of the invention which
will‘ be‘ described hereinafter‘ is particularly ap
bottom end‘. of" the’ said cylinder, is, fitted within,
a bottom head‘er‘i whichv is described. herein
.The bottom end of an inner tube 6 is
?xed in a seating provided in the bottom header
that when the valve is on its seat, little or no load .
is applied by the spring, and when the valve is ,
and its upper end is provided with an inverted
cup ‘I having a hole 8 in its end wall. An ac
lifted to the full extent the load applied is such as ~
cumulator piston 9 comprising a metal-reinforced
to exert the maximum desired resistance to the
rubber sealing member II] having two sealing
edges H and I2 is slidably arranged in the inner
?ow of liquid through the apertured collar 39.
The guide comprises an inwardly extending stem '
44 on one side of the shoulder and an outwardly
extending stem 45 which is screwed into the outer ‘
‘ tube 6 and is normally forced downwards there
in by means of a number of coaxial coil springs
I3 disposed in the tube between the piston 9 and
wall of the valve'box. Bythis construction, the
the said cup 1_ The bottom end of the lower
most spring I3 is seated in a cup l4 bearing
initial loading of the valve spring 4| can be ad
justed by screwing the valve guide 43 inwards or
against the piston 9 against which thesaid seal
‘ outwards and a lock nut 46 on the screwed part
ing member is clamped by a clamping member’ "
of the guide serves. to ?x the latter in any of its
' l5 mounted upon a rod-like extension I6 of the ,
adjusted positions. The holes 39 in the said disc
valve seat 31 are adapted to be closed by a large
?at valve 41 which is arranged'at the opposite
side of the seat in a lateral cavity'48 provided in
piston and forced against the sealing member.
by nuts I5A.
The said cup I4 is slidably ‘guided _ \
in the tube ‘6 and the upper end of the springis
arranged in an inverted, apertured cup I ‘I slid-‘- " - ‘the bottom header and in communication with
able in the tube.
Each of the other springs 13“ ‘
is ?tted at its lower end in an apertured, slidable .
the interior'of the body 28 of the header. A coil
spring 49 of light rating-is arranged in the‘said
cup MA with an upwardly-directed skirt, and
at its upper end in a similar cupIlA witha
lightly on to its seat so as to "close the" holes
cavity and acts to press the ?at va1ve4'l relatively
downwardly directed skirt. The top‘ cup-HA‘ of
the upper spring bears against the cap ‘I atcthe
top of the inner tube 6. '
The advantage of this arrangement is that by
using a plurality of springs, the length/diameter
ratio of the individual springs may be sochosen
that the spring is free from any appreoiable'tend
ency to lateral buckling. Should su’ch buckling .
occur, a large and indeterminate frictional com
ponent would be" superimposed on the'normal
action of the spring, By this arrangement, a
long, relatively narrow spring which would be
ing the same degree of resiliency as the single
An outer tube I8 is slidable through the open-'
ing in the end of the hollow cap 4 in the end
ber sealing member 52, having two sealing edges;
53 and '54, being arranged 'invthe skirtypartof'
the cup and secured therein by a clamping mem-'
ber 55 ?xed by an apertured cover 56 closing
the end of the cup. Thesaid sealing inembervacts
seriously unstable laterally is replaced by a num- ~
ber of laterally stable relatively short springs have
33 in the valve seat. >When lifted oil its seat"
the valve is guided by ribs 48!} in‘ the cavity ~48.‘_
An operating piston 58 is ?tted‘on the bottom,
end of the outer tube I8 and comprisesapiston
part 5| which is of cup form and is slidable- in’,
the operating cylinder I, a metal-reinforced rub
to prevent oil leakage past the piston along- the
'The top header 2‘ is provided’ with a: lateral
cavity'5l, which communicates withthe interior’
of the header above the top of operating cynn:
der I andis closed by‘arvalve box 58 similar ‘in
constructionto the ‘bottom valve box 36 and also‘
of'the top, header 2, a metal-reinforced rubber 4.0» containing identical‘ valve, valve ‘seat and spring".
sealing memberI9 having two sealing edges. 29
mechanisms 48a, 41a, _3'Ia,“4|a and 49a. The;
and 2| being, arranged in the cap. and ?xed there
in by a clamping member 22 and a cover 23 closingv
springs 49 and 4% are adapted to load thevalvesl,
the end of the cap. The cover is formed with. an
loaded. The interiors of the top and bottom .valve
4,5.1 boxes
36 and 58 are'connected by a transfer tube
annular recess surrounding the tube and packed
with dirt excluding packing 24. such as .felt. 'A'
cap 25 comprisinga forked connecting member
26 is ?xed in the upper end of the outer tube I8,
and is pivotally connected to a suitable ?xed part‘
of the aircraft (not shown).
The bottom header 5 is of box form and it com
prises a lower passage 27 forming the seating vfor
the bottom end of the inner tube 6 and, before
41 and 41a at a lesspressurethanjthe piston 9,, is
59. The hole 6i]v in the cap 25 at the top of the’
outer tube I8 acts in conjunction'with,thejhole
8 in the cap ‘I on the inner tubetoput the‘inrf
teriorof the latter above thepiston 9 in ‘come '
50-' munication
with atmosphere.
In operation, theoscillation of ‘the: said me'm-If
ber 32; see. Fig. 2, pivotallyattaohed to; the ibbt? 7
tom ‘header. 5 causes the latter, the .lbperating
the latter is'?tted, communicating 'at itstop end 55. cylinder. I, the top header 2, the, inner tube. sane '
with the interior of the hollow body part. 28, ‘ the accumulator ‘piston 9, the two. valve‘ boxes
which is of greater area. The bottom of the said
36'a'nd 58 and ‘they transfer tube 59tobemoved
passage 27 is closed by a plug 29 formed externally "
relatively to theouter tube I8 and operating pis-i
with a fork 3!] to which a member 3| on an oscil
ton 50. The annular spacebetween the cylinder
lating lever 32 is pivotally attached, as shown in 60 land the outer tube, the-headers, the valve‘
Fig. 2. An oil inlet 33, ?tted with a ?ller nipple
boxes, the transfer tube and the inner, tube’are
34, communicates with the said passage 21v and
filled with a suitable liquid,~rsuch as ‘oil; [Assume
the latter also communicates with a transverse
ing that the oscillating member 32 is moved:
passage 35 leading to a valve box 36'which is se- .
downwards from the position OX, liquid on§top
cured to: a lateralface of the bottom header. A . of the ‘operating piston 58 is transferred sup’:
valve seat 31 is held between the contacting faces
wards in. the cylinder I and through the top
of the bottom header and valve box, the said seat
header and, after having forced the ?oW-rresiste
being in the form of a disc, which is provided with
ing valve 48a off its seat ‘31a, ?ows through the
a number of holes 38, and with a central apertured
transfer tube 59 into the bottom valve box 36.
collar: 39 extending into the valve box. A. ?at 70. The liquid forces the larger ?at valve 41, in the
valve 49, guided for’ movement towards and from
bottom valve box off itsseat and is transferred
the end of the collar 39, is normally pressed
through the holes'38 in the valve seat 31into
on to the said end by a'coil spring 4I arranged
the space 28 in the bottom header around the:
‘ between the flat valve and’ a shoulder '42 on a
inner tube and into the cylinder I below-the
valve guide 43. The spring’ 4| is of such a rating ' operating piston 59. ‘Owing'to the ldi?erencejinf V
thel outertpiston 31 the volumef-off' liquidiudi'splace‘d
between; the end; of-n said ' operating;v cylinder: and‘
adjacent end‘? of? said transfer- conduit,.. sovthat
above the piston‘ is‘ less. than: that: entering‘ the
cylinder! below. This’ deficiency is: made- up‘ by
piston must'fi-rsti open onefof’i said’ valves , before
the: areaeofi the: annular? spaces above». and ‘below
liquid displaced in saidloperating-cylinder by said
the" springepressed'; accumulatorrpiston: displac
it‘v can» enter' said‘l'transfer conduit, a‘ piston rod
mg: the: necessary- quantity: of? make-‘up liquid
which projects through one end of said‘; operating
cylinder and which serves to- connect said‘ ‘oper
fromlthe inn'ertube?linto the bottom; header and
ating‘ pistoln‘rtos arr- anchorage or to- a! member
whose" movements are to be damped; and‘, resil
takes place when the oscillating’ memberv 3211s 10 ient means for compensating» forfthedi?brential
action 1 of said‘ operating piston - and; f ‘or the ~ effect
rocked inthe.v oppositedireotion; the inner' tube
thencerinto. the valverb-on andithroughthe holes ,
38 below the operating piston 56% a
of- temperature changes‘ ofltheg' liquid? byv main‘;
taining the liquid under-‘pressure, said ‘resilient
?itheni receiving, theiexc'essv liquidi displacedfbelow
the-operating piston"; vi'aivthe passage, 35.:
means com-prising a‘ spring-pressed. accumulator
spring-loaded inner piston~z9 ' functions as‘v an‘. ac
cumul'ator piston‘ an'd'I acts‘, to‘: put‘:- the ‘liquid in
piston slidable' in‘ a‘ liquid-containing‘ cylinder
the‘ tube 6% un derr' initial : pressure-auditor-compare
which communicatesiat one; ‘end? with.‘v said transi
fer‘v conduit between said passageways and-i‘said'
?ow-resisting valvesin said‘: headers,‘ said: oper
saterfori'any changes‘. in thet'emperature: of: the
liquid; asswell as . actingi asnai liquid’ volume. com
ating' piston» beingi tubular'and being-i slidably
' 3.,
It will be appreciated that the reverse action 20 mounted upon said- liquid-containing cylinder;- >
‘ 2. A damping; vdevice of; the class: described;
taltes'ip'lacev when»- the' oscillating member rocks
comprising an Operating cylinder having an oper
ating piston therein and provided at each end
in the opposite direction from the position OY in
which case liquid is displaced from below the '
with a hollow header, a passageway in each of
operating piston above it. In both cases, the
damping action is brought about by the resistance
o?ered to the transfer of the liquid from above
(or below) to below (or above) the operating pis
ton 5!!‘ by the said smaller ?at valves 48a and
40, which are loaded by the springs Ma and 4|‘.
By this means, the magnitude of the damping
action is dependent primarily upon the force
exerted by the valve loading and not upon the
viscosity of the liquid. In other words, the energy
said headers communicating with the interior of
said operating cylinder, a transfer ‘conduit con
necting said passageways in the two headers, a
flow-resisting valve disposed in each of said pas
sageways between the end of said operating cyl
inder and adjacent end of said transfer conduit,
so that liquid displaced in said operating cylinder
by said piston must ?rst open one of said valves
before it can enter said transfer conduit, a piston
rod which projects through one end of said oper
ating cylinder and which serves to connect said
absorption is provided by the work done by the
liquid in forcing itself past the valve Mia or 49
against the opposing force of the loading spring
operating piston to an anchorage or to a member
Ma or M, in contradistinction to known damp
ing means wherein the energy absorption is due
whose movements are to be damped, and resilient ,
,means for compensating for the differential ac
tion of said operating piston and for the effect
40 1of temperature changes of the liquid by maintain
ing the liquid under pressure, each of said ?ow
In the event of the loss of liquid from the
to the viscous flow of liquid through one or more
device by leakage, for‘. example, the piston 9
resisting valves being adapted to open and close '
might‘ be thrust so far downwards by its springs
that the end of its extension 16 would act as a
stop and engage with the cap 29, thus prevent
ing the edges II and i2 of the sealing ring it
becoming disengaged from the bore of the inner
anaperture in a valve seat, said valve seat also
being formed with a number of holes adapted to
tube 6.
1' be opened and closed by a non-return valve nor
mally held closed by a spring applying less pres
sure to said non-return valve than the pressure
created by said resilient means, each of said non
return valves acting to allow liquid displaced into
It will be understood that the damping device
is equally applicable to the damping of the move £30 said transfer conduit from one end of said op
erating cylinder by said operating piston .to ?ow
ments of two members each movable relatively'to
into the opposite end of said operating cylinder.
the other. The device can also be arrangedlhorin
3. A damping device of the class described,
zontally or at any other angle to the vertical,
comprising an operating cylinder having an op
and the oscillating member 32 can obviously be
connected to the operating piston and the bottom ‘ '
erating piston therein and provided at each end
header 5 to a ?xed anchorage.
with a hollow header, a tube on which said oper
ating piston is mounted projecting out of the de
In order to vent air from the device when the
vice through one of said headers and which is
latter is being ?lled with liquid, the headers 2
provided with means wherebyit may be attached
and 5 are respectively provided with screwed air
vent valves 6! and 62. As the device is usually 60 to an anchorage or to a member whose move
ments are to be damped, said header at the op
?lled with liquid under high pressure supplied
posite end of said operating cylinder being pro
through the nipple 34, a spring-loaded liquid re
vided with means whereby it may be attached to
lief valve 63 is ?tted to the valve box 58.
the member whose‘ movements are to be damped
It will be obvious that the invention is adapted
or to an anchorage, a passageway in each of said
to be used for purposes other than that specif
headers communicating with the interior of said
ically described above.
operating cylinder, a transfer conduit connecting
I claim:
said passageways in the two headers, a ?ow-re
1. A damping device of the class described, com
sisting valve disposed in each of said passageways
prising an operating cylinder having an operat
between the end of said operating cylinder and
ing piston therein and provided at each end with
adjacent end of said transfer conduit, so that
a hollow header, a passageway in each of said
liquid displaced in said operating cylinder by said
headers communicating with the interior of said
piston must ?rst open one of said valves before
operating cylinder, a transfer conduit connecting
it can enter said transfer conduit, and resilient
said passageways in the two headers, a ?ow-re
sisting valve disposed in each of said passageways 75 means mounted within a cylinder adapted to be
rtelescoped into said tube for compensating for the
differential actionof said operating piston and
for the effect of temperatureychangesof the liquid
silient means comprising. ‘a , spring-pressed 3001i;
mulator piston slidable in a liquid-containing cyl-if
inder mounted within said operating cylindervand
by maintaining the liquid under pressure.
' ,4. A damping device ‘of theclass described,
communicating at one end with said transfer con;
comprising an operating cylinder having an op
sisting valves in said headers, said operating pis
ton being tubular and being slidably mounted
upon said liquid-containing cylinder, and atue
bular piston rod mounting said operating piston
erating piston therein and provided at each end
with: a hollow header, a passageway in ‘each; of
said headers communicating With the interiorv of
said operating cylinder, a transfer conduitcon
nesting said vpassageways in the two headers, a
?ow-resisting valve disposed in each of said pas- '
sageways between the end of said operating cyl
inder and adjacent end of said transfer conduit,
so that liquid displaced in said operating cylin
der by said, piston must ?rst open one of said
valves before it can enter said transfer conduit,
duit between said passageways and said ?ow-reg ~
and telescoping over said liquid-containing cyl
inder, said tubular piston rod projecting outof
' the device through, one of said headers and being
provided with means whereby it may be attached,
to an anchorage or to a member whose move‘
ments are to be damped, said headers at thevop
posite end of'said operating cylinder being-pro
vided‘ with means whereby it maybe attachedito
resilient means for compensating for the di?er- ~
the member whose movements are-to be damped
ential action of said operating piston and for
or to an anchorage.
the e?eotof temperature changes of the liquid
by maintaining the liquid under pressure, said re
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