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Патент USA US2405006

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July 369 îlgáìä .
Filed Jan. 27, 19444
2 Sheets-Sheet 1
July 30, i946,
Filed Jan.. 2'7", 1944
2 SheetsFSheet 2
Patented July 30, 1946
Benjamin N. Ashton, Kingston, N. Y., assignor to
^ Electrol Incorporated, Kingston, N. Y., a corpo
- ' ration of Delaware
Application January 27, 1944, Serial No. 519,844
6 Claims.
(Cl. 103-23)
This 'invention' relates to` improvements in
pumps and relates more particularly to continu
ously driven pumps suitable for supplying liquid
under pressure to hydraulic systems, such as, for
example, the hydraulic vsystems used in aircraft
for actuating retractable landing gear, folding
wings, Wing flaps and the like.
connected relationship until the pressure falls to
a predetermined lower value.
More particularly, pumps of the type embody
ing the present invention may include a plurality
of cooperating cylinders and pistons provided
with suitable intake and discharge ports through
which liquid may be drawn and discharged by
the action of the pistons. The pistons may be
The .pump óf vsuch a hydraulic system usually
is driven _by the aircraft engine and it delivers
reciprocated by means of a suitable drive mech
liquidunder pressure at all times during the op 10 anism such as a wobble plate that is actuated by
eration oí. the engine. Inasmuch as the various
means of a cam connected to and driven by the
hydraulically operated elements of the aircraft
are actuated intermittently, the continuously
engine so that upon rotation of the cam, the
pistons are successively advanced and retracted
supplied liquid under pressure must be diverted
in their respective cylinders.
and recirculated in order to avoid excessive pres
sure in_and damage to the hydraulic system.
' The liquid usually is V_diverted andlrecirculated
by means otadevice known as an unloading
valve, ¿whichfoperates -to bypass and return the
liquid to a reservoir or tothe inlet of the pump
when a predetermined pressure has been reached
in the system.
An object of the present invention is to pro
vide a pump that is responsive tov pressure in a
hydraulic system and is capable of maintaining
in the system a hydraulic pressure within a pre
determined relatively narrow range.
Another object of the invention is to provide a
The wobble plate may be supported upon a
piston member that is displaced by liquid pres
sure on one side thereof to disengage the wobble
.plate from the cam. -Liquid under pressure may
>be supplied to displace the piston by means of a
20 valve mechanism that Yis shifted to an open posi
tion by a predetermined iiuid pressure in the
hydraulic system and maintained in such open
position until the pressure in the system drops
a predetermined amount.
When the pressure in the system drops to a
predetermined value, the valve mechanism is re
set to discharge the liquid from behind the wobble
plate piston to permit the wobble plate to engage
`with the actuating cam and actuate the pump
continuously driven pump that automatically
ceases pumping when a predetermined liquid 30 pistons.
pressure is attainedin a hydraulic system, and
Pumps of the type described generally above
permit the unloading valve and associated con
resumes pumping upon a predetermined decrease
of the pressure in the system.
duits of prior systems to be eliminated inasmuch
A- further object of the invention is to .provide
as the pump functions both as a pump and a
a positive type of pump having continuously op 35. pressure control mechanism.
erated driving mechanism that is rendered in
For a better understanding of the present in
eiïective -to actuate the pumping elements when
vention, reference may be had to the accom
the pressure in >the system attains a predeter
panying drawings in which
mined maximum value and in which the pumping
Figure 1 is a view in longitudinal section of a
elements are rendered eiiective when the pres 40 typical form of a pump embodying the present
sure in the system falls below a predetermined
Figure 2 is an end view of the pump; and
Figure 3 is an enlarged showing of a portion
parent from the following description of typical
of the pressure-responsive valve of the pump.
forms of pumps embodying the present invention.
The form of pump chosen to illustrate the in
Pumps of the type embodying the present in
vention includes a generally cylindrical housing
vention include pumping elements that are ac
I0 having a circumferential iiange 10a at one end
tuated by a drive mechanism that is coupled to
thereof which abuts against a iiange Ila on the
and driven by a motor or an engine, for example,
end of a generally cylindrical pump body portion
an aircraft engine. The pump is provided with 50 ll. The pump body portion il, as illustrated, is
a pressure-responsive mechanism that is actu
` provided with a plurality oi’ cylindrical bores I lb
ated, upon attainment of a desired liquid pres
forming cylinders disposed around its periphery
sure in an associated hydraulic system, to dis
for receiving the cylindrical pistons l2. The
pump body portion ll is also provided with a
connect the drive mechanism completely from
Other objects of the invention will become ap
the _pumping elements and maintain such a dis
cylindrical recess llc forming another centrally
"iff: if...
with each of the pumping cylinders l Ib by means
cylindrical portion 28a of the member 28 is re
ceived in a cylindrical cavity 28h coaxial with the
of the inlet ports I ld.
At the left hand end of each of the bores iIb
is a bushing I3, forming a check valve seat, which
is threaded into the member I I and sealed there
lying the race 2‘Ic. The clamping member 28 may
be retained in position by means of a bolt 23
disposed cylinder therein which communicates
recess 26a and similarly inclined at an angle to
the axis of the shaft 22, with its flange 28h over
threaded intothe. .member 2S.
to by a suitable sealing ring |3a.» _--The cooperat
mutation on a ball member 3| mounted on
le ~and
a"shaft 32. The shaft 32 is slidably and rotat
ably mounted in the end of the pump body || and
extends axially of the cylindrical cavity ||c into
fthfe Cylinder L59. @The ball 3| is mounted on a
is normally urged toward its valveseat »i3by
means of a coil spring I5 interposed`bet'we`enïthef~
back of the plug I4 and the end closure cap IS
of the pump. When the plug |_4 is seated, it en
gages the sealing ring Iâî) 4and the face of the `
seat I3 inwardly of the ring I3 so that liquid pres
sure on the ring Iâhand the plug I4 provides a
reduced portionß‘gìd of the shaft 32 and is re
tained thereon by means of a nut 33. The wobble
plate 30 includes a pair of telescopically assem
. bled-disc-like members 30a and 3ûb having a
partially spherical aperture 35e therein for re
ceiving the ball 3|. The members _373e _and 30h
strong and complete séál _betweenthe plug I4
_. ..
a wobble plate 3D thatismcunted forP rotation
may consist of a cup-shaped element havirne‘ a
flat cr disc-like valve face |4a that cooperates
with a »sealing ring |3b mounted in a groove |36
in the valve seat I3. Each of the valve »pl-ugs I4
and theseatilì.
._ 'ïîhe outer race'f2'l‘a o_f ïthebeariugzjpngages
ing element`.o'r'.valvè}fplug I4 of the check ¿valve
have an inter?tting projection 3_Ild_a_nd_reces_s _38e
`.Asshown in Figure 24 the capl Ilì is‘generally
dis’o'ëlìlçe in plan and is provided ,with an annular
axially'd'irectedflange |80?l that abuts against the
ña?igeflIa ofthe pump body. vThe cap I6, the
pump'body II' and the casing Il! may be secured
together by means_ef va plurality- of bolts |1 pass
andare connected by means '_of 'a‘ series of 'bolts
35 _which extend through overlapping portions
ingA Ahrough the ,ñanges lila. |€a_ and threaded
threaded into an internally threaded portion' of
intolth'e -flange |641.-
of themembers 30a and 30D. - '
The wobble plate _30 is provided with a plurality
of radially extending openings 301‘ _for receiving
the studs 36. Eachfof thestuds 36 is Provided
with a reduced threaded ’portion 36a which is
the bores 30f.
j Escape of liquid from between ‘the cap i6 vand
`-: '
, "
The studs 36 -have Vgenerally spherical `heads>
the. flange IIa’ maybe prevented by means- of
36h that are received in transverse openings I2a
a suitable rubbery sealing ring or gasket I8 re
ceivedr in a groove IIe in Íthe pump body and en
in _the reduced end 'portions 1.21) ofthe pistons
I2 so that nutation ofthe wobble -plate '30 will
cause _the pistons“__|2_-to reciprocatein the cylin
gagíng the .flange IBG.' The pump cap I6 iS pro
vided with ananfnular flange _I Bb concentric with
Tìhëi flange 'lie re’ò'eîifedßslessp'pîcally inthe..
ders _`||b. ->'l'husjiupon'rotation‘ of the shaft 22,`
theïdr'" _'ng ¿ein 21 will-‘cause ,riut'auon'of the' wob
bie' pratëiaviändï ui'ëfîbis'tohswiu be‘ actuated to
Cylindrical. recessmeans'of
¿IIC .G_Lf îthe
‘al rmripbedy
ali‘ngrin'g‘or and
the' _liquid 'to' tlíeîhydraulic 'system'.f
ISmounted‘in an annular groove _läd 'in the nan‘ge
pressures vby the system by the pump', the cap
|6 of the pump is provided with- a valve -mecha.
nism which -controls the position of the `wobble
plate 30 and renders theyistons I2 'effective'or
ih_ë ‘flange- Iêd and an’i'uner concentric flange |5c
forming, 'a _cylin'd
„ riapurpose‘to' be described.
draw liquid into the‘cylinders Iflb -and discharge-Y lin-order- tó 'avoidwthè' development 'of excessive
|612; vThe annular space 2_9 between the flange ißc
and the ilange` Iëb‘ communicates with a dis
charge coupling Iâe inthe cap I6. The coupling
I_lìc is. adapted to be connected to a hydraulic .Sys
ineffective to pump, depending upon the pres
tem so that -the liquid forced from the cylinders
|_ lb> through the check valves I3, |4 into the cavity
sure in the system.
tem for use'in actuating various elements ccn
nected therewith.
’_I‘he valve, together with the inlet port |6f and
29___will be „delivered directly to the hydraulic sys
lï'h'e cylinder I__Ic >andthe space'2! within the
flange Iëb are'~conne~cted to an inlet coupling |6í
the discharge port |66 is disposed in a boss or a
thickened portion I_Bg on the cap I6 as shown in
Flgures'l and 3 of the drawings. The boss |69
in. the c'ap‘lûso that liquid _from a reservoir or
from the hydraulic system-:can ñow into the cyl
is provided with an axially extending bore -Iíïh
which terminates adjacent to thedischarge cou
pling IBe and is connected thereto by means of a
inder itc and tothe intake ports lld.
:The pistons i2 are actuated'by means of a shaft
annular valve seat 40 having a. tapered opening
small passage _|612 Within the bore _ISh'fis an
40a communicating with a-cylind'rical passage 4Gb
defining with the'upper face _of the member 40 a
22'thatis driven by a motor or engine. The shaft
is journaled in suitable anti-friction ~_bearings 23
¿ne 24 that are mounted in a portion lob or _the
sharp edged `'valve sea-t v_llllcjf'o?a ball valve 4|.
casing I3 of reduced diameter. In order to pre
andis maintained in- spaced relationship tothe
A sleeve member Y42 is ldisposed in the bore |671'
vent leakage around the shaft, an oil seal 25 of
member 4D by means of an annular spacer mein
conventional type may be interposed between ‘the
shaft and vthe portion lilb- Of the casing.
The -inner' end of the shaft 22 is provided with
accunter-balanced driving cam. For example,
the shaft 22 may be provided with a counter
balancing member 26 having an eccentric and in
clined arcuate recess 26a therein for receiving a
ber 43 of generally VL-shaped cross-section. ' 'v
The member 42 is provided »with an enlarged
internal bore 42a and a smaller passage 42h that
forms with the lower face of the member 4_2- a
sharp edged valve seat 42o for the ball "4|.-` -The
diameter of the passage 42h is somewhat greater
than the diameter of the passage '401).
roller-bearing’driving member 21.' The driving
member 2ï may include an outer' race 21a sup
ported by a plurality lof tapered roller bearings
2lb and an inner race member fìlc. i The inner
race Zic is clamped in the recess 26a onthe coun
' ` t
The ball 4| is normally-urged against theï-valve
seat 40o by means "of _a plunger-"44which ex
tends axially of the bore -I Gg? and is provided with
a reduced end- portion- 44a that ~projects through
passage 4_2?) andA _engages -_th`e "'ball." The
ter-'balancedmember 2S by means o_f'a flanged, _ the~
cup-shaped, clamping VAmember 28; The base or 75 plunger 44 -is also-provided with la-'i‘lamgeMb that
is engaged by a coil spring 45 extending between
the llange 44h and a member 46 threaded into the
outer end of the bore lIîg for adjusting the prese
sure exerted by the spring 45 on the ball 4I.
The members 40„43 and 42 are retained in ñxed
relationship by means of a tubular sleeve 41
threaded into the bore IIìh and retained in iixed
position by means of a lock sleeve 48 also thread
ed into the bore IBh.
square inch. When the pressure in the system
attains the desired value, the back pressure in
the system, acting through the passage |61' will
displace the ball 4I from the valve seat 40e
against the action of the spring 45. The spring
45 is adjusted or selected so that it will re
tain the ball 4I on the valve seat 40o until the
desired pressure is attained in the system. When
this pressure is attained, the spring 45 is com
The spring adjusting member 45 is provided 10 pressed and the ball 4I is displaced upwardly
as viewed in Figure 1, urging the ball against
with an internal flange 46a that closely receives
the valve seat 42o. Inasmuch as this valve seat
the plunger 44. A resilient sealing ring 49 is in
is of a greater diameter than the valve seat 40o,
terposed between the flange 46a and a ring 50
the effect of the pressure on the ball 4I is con
against which the spring 45 bears to prevent leak
siderably increased. Thus the diameter of the
age around the plunger 44. The adjusting mem
seat 42e may be such that the pressure in the
ber 46 may be locked in `adjusted position by
system»must drop to 900 lbs. per square inch
means of a lock nut 4Gb threaded on its exterior
before the spring 45 can return the ball 4I> to
and engaging a compressible gasket 45e received
the seat 40e.
in a recess |67’ at the end of the boss I6g.
The spacer member 43 is provided with one or ,A
more radially extending ports or passageways 43a
that communicate with a groove 42d in the outer
periphery of the member 42 and a passage 5| in
the cap member I6 communicating with the
space within the tubular member I6c in the in
terior of the cap I6.
The interior of the cylinder IIc and the space
between the flanges I6b and I6c are connected
with the interior of the sleeves 41 and 42 by means
of a passage 52 and a passage 41a through the
sleeve 41.
With the ball in its displaced position, liquid
flows through the passage 43a, the groove 42d
and the passage 5I into the Space between the
end of the plunger 32h and the annular flange
IEc. The liquid also flows through the passage
32o and 32d behind the piston 53, thereby urging
the piston to the left against the action of the
spring 54 and moving the wobble plate 30 out
of engagement with the drive member 21. In
the form of the invention illustrated, the wobble
plate 30 will engage the end of the pump body
portion II and will be rocked into a position
substantially perpendicular to the axis of the
shaft 32. This movement of the wobble plate
advances all of the pistons I2 to the left where
they are retained so long as the ballv 4I is dis
placed from the seat 40C.
When the pressure at the discharge port or
The valve construction and passages described
above are utilized to actuate a piston 53 that is
fixed to and carried by the shaft 32 and movable
axially of the cylinder IIc. The area of a face
of the piston 53 is greater than the combined
areas of the faces of the pistons I2. The piston
coupling |66 decreases sufñciently, the spring 45
53 is sealed to the cylinder I Ic by means of a
and plunger 44 displace the ball from the valve
rubber sealing ring 53a supported in a peripheral
seat 42o and return it tc engagement with the
groove 531) in the piston. The piston 53 and the
seat 400. In this position, the liquid behind the
shaft 32 are normally urged toward the right by
piston 53 flows through the passages 32d, 32o,
means of the spring 54 that engages the piston
the passage 5I, the passage 43a, the port 42h,
53 and the cap member I6 and encircles the shaft
through the ports 41a and 52 and into the cylin
32. The shaft 32 extends beyond the piston 53
and is reduced in size to form a piston 32h that 45 der IIc. This releases the pressure behind the
piston 53 and permits the spring 54 to move the
is slidably received within the tubular rmember
I6c. 'I’he piston 3217 is maintained in liquid tight
relation to the member I6c by means of a rubber
sealing ring 54 and is provided with an axial
bore 32o that intersects an inclined passage 32d
opening to the exterior of the shaft 32 at the
right hand side of the piston 53 so that liquid
flowing through the bores 32e and 32d will be
discharged into the space between the right hand
end of the cylinder I Ic and the piston 53. A suit
able sealing ring or gasket 55 may be interposed
between the cylinder IIc and the casing I0 and
encircling the shaft 32 to prevent leakage.
In operation, with the shaft 22 driven con
tinuously, the wobble plate 30 is nutated to re 60
ciprocate the pistons I2 in their respective cylin
piston to the right, thereby reengaging the wob
ble lplate 39 with the driving mechanism 21 and
causing a resumption of the pumping opera
The above described construction, therefore,
provides a pump which automatically cuts off at
a predetermined pressure and resumes pumping
at a lower predetermined pressure, thereby do
ing away with the necessity of providing a sep
arate unloading valve for a hydraulic system,
while assuring that the pressure in the hydraulic
system will remain within a. desired operating
While the invention has been described with
reference to a piston type of pump, it will be
understood that it may be utilized in conjunction
ders IIb.v Liquid is supplied through the cou
with other types of positive acting pumps.
plingf I6f to the cylinder IIc and is drawn into
Therefore, the form of the invention as de
the cylinders I Ib through the ports IId by means
scribed above should be considered as illustrative
of the pistons I2. As the pistons advance past
and not as limiting the scope of the following
the inlet ports IId, the liquid is forced out
through the check valves I3 and I4 into the
space 20 and` thence to the discharge coupling
I claim:
ISe. As the pistons retract, the check valves
1. An automatic cut-off pump comprising at
I3, I4 close and a reduced pressure is created 70 least one pump cylinder having an inlet and an
in the cylinders, thereby drawing the liquid into
outlet, a piston reciprocable in said cylinder to
the cylinders IId for subsequent discharge. As
draw liquid into said cylinder through said inlet
the pump continues to operate, the pressure of
and discharge liquid through said outlet, rotary
the liquid in the system is increased to a pre
driving means, a wobble plate actuated by said
determined value, for example, 1090 lbs. per 75 rotary driving means for reciprocating said pis
ton, and means responsive `to va predetermined
liquid ¿pressure :at .the outlet of said cylinder for
shifting said »wobble plate «out of »engagement with
said rotar-y driving means to render that `latter
able member, said means retaining said wobble
.plate in shifted position until the `pressure in
saidsystem .drops to ya predetermined `lower value.
5. An automatic cut-.oli pump .comprising at
ineffective to reciprocate »said piston, said `pres
least one .cylinder .having an inlet .and .an outlet,
sure .responsive'means being responsive .to a lower
pressure than said predetermined pressure to
a ,piston ,reciprooable in said .cylinder for `admit
ting liquid through ,said inlet into said .cylinder
and discharging liquid under 4pressure through
shiftsaid wobble plate into engagement with said
rotary driving means to render the latter «effec
tive 4to reciprocate said piston.
said outlet, a rotatable member having .a face .rin
10 clined to the axis .of .said cylinder, a wobble plate
liquid from `said outlet under pressure, Y.a ymtary
cam member ladjacent ,one end of said piston, a
connected to .said piston, .means supporting .and
urgingsa'id plate against said inclined face to re
ciprocate said piston upon rotation of said mein
ber, a piston on said supporting and urging
means, a .cylinder for said last-mentioned piston,
a valve >having a ¿first port connected with said
power transmitting element engaging said _piston
outlet .and the last-,mentioned cylinder, a sec
.2. An automatic .out-off pump comprising a
`cylinder having an 'in-let 'and an outlet, a piston
reciprocable in said cylinder to dra-w liquid linto
said cylinder ’through ysaid inlet and .discharge
and said cam member for reciprocating said pis
ton >in response to rotation of said cam, and means
responsive to a predetermined liquid pressure at
said outlet for moving ysaid power transmitting
element .out of .engagement Ywith said cani to ter
minate reciprocation .of said piston.
automatic cut-ofi ,pump Icomprising a
'pump body having >a plurality of substantially
@parallel cylinders radially spaced about the axis
of said body, pistons reciproca-ble -in said cylinders
¿for `drawing liquid into -said cylinders and dis
charging .'liquid yto a ihydraulic system, a driving
-memberhaving a vface inclined tothe axes of lsaid ‘
ond port connected with said last-.mentioned cyl
inder and said inlet, a Vvalve member for sealing
either of -said ports and means normally urging
said valve member into said first port, whereby
displacement of said valve member from said ñrst
port by liquid pressure >atsaid outlet admits .liquid
.to .said last-mentioned cylinder to `displace said
wobble plate from engagement with said inclined
face, and displacement of said valve memberirom
said second -port discharges liquid ’from said vlast
mentioned cylinder to Areengage said wobble plate
with said inclined face.
v6. An automatic .cut-olf pump comprising .a
body and said cylinders, and adjacent to Ithe
pump body having a substantially centrally .dis
end of each of said pistons, a wobble plate oper
ated by said .member interposed between said end
of each piston and said driving member, means
.urging said end of each piston'toward said driv~
.posed cylinder and a plurality .of substantially
ing member, means for rotating said driving
of said smaller cylinders, a larger piston in said
parallel smaller cylinders disposed radially out
wardly .of said centrally disposed cylinder, each
having an inlet and an outlet, a piston in each
centrally disposed cylinder, a Vshaft projecting
`member .and .said body relatively to cause nuta~
from said larger piston, 4a wobble-plate mounted
tion .of ¿said wobble ¿plate to reciprocate said pis
for nutation on said shaft and connected to .each
tons'in said cylinders, .and mea-ns responsive to a
tpredetermined pressure tin said hydraulic system (if) of the _pistons in said smaller cylinders, a rotat
able -driving member having an inclined face ad
«for shifting said wobble plate to move said ends
jacent >to said wobble plate for nutating the latter
vof said .pistons :into Aa plane substantially per
-to reciprocate said .pistons in said smaller cylinpendicular to theaxis‘of said -body to .render rela
ders, means urging .said >wobble-plate and large
4tive rotation 'of said body and said idriving mem
1 Vpiston toward said .driving member, a two-posi
:ber ineffective ïto reciprocate said pistons.
tion valve having -a ñrst port vconnecting said
¿4.,An :automatic vcut«o?f ¿pump comprising at
centrallydisposed cylinder with the outletsvof said
Vleast one 'cylinder having ¿an inlet .and an outlet,
smallerl .cylinders to deliver liquid under pressure
a :piston reciprdcable :in said .cylinder 'for ,ad-mit
yto »displace said larger piston in Opposition to
«ting .liquid 4through said inlet 'into -said cylinder
and discharging liquid under pressure through »_, -sai-d Avurging means, a second larger _port connect
Íing the centrally `disposed cylinder with said in
.said .'.outlet, .a rotatable Vmember having a face vin
lets -to discharge liquid from said .centrally dis
clined-to theaXis-oi said cylinder, a'wobb-le plate
posed ;cylinder to said inlets, a valve member .for
connected `to said piston, ymeans supporting and
sealing said Iports alternately, and means nor«urging said plate .against said inclined >face to
- ~, mally urging said valve member intosealing rela
reciprocate .said .piston .upon rotation .of said b.
tion with said yiirst port.
member, .and means responsive to a predeter
mined _pressure at said outlet for yshifting vsaid
-wobble plateout of engagement with _said rotat- .
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