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Nov. 12, 1946.
J_ W, KELLY
HYDRAULIC SYSTEM
Filed Feb. 9. 1943
»
`
2,410,978
Patented Nov. 12, 1946 ,
2,410,978
UNITED` STATES PA'rl-:Nrforrlcg, j
HYDRAULIC SYSTEM
John 'william Kelly, La canada, Calif., assigner;
t'o Adel Precision Products Corp., a corporation
of California
Application February 9, 1943, Serial No. «l='i'5,3Il1__A
9 Claims.
(Cl. (iO-54.5)
1
2
This invention relates to hydraulic control sys
tems for aircraft and more particularly pertains
to a manually operated hydraulic control system
claimed, and illustrated by way of example in the
accompanying' drawing; in which:
which is especially adapted for operating the
throttles of aircraft engines or other aircraftA
controls or mechanisms subject to manipulation
through the medium of such a system, rather
than mechanical means or power operated hy
.
»
Fig, 1 is a semi-schematic view of `a hydraulic
control systemembodying my invention withr all
valves closed `and »the ymotor unit hydraulically
locked against movement from exterior forces;
Fig. 2 is a‘semi-schematic view corresponding
to Fig. 1 but showing the’thermal expansion relief
draulic systems.
valves as whenv opened to relieve excess pressure
A primary object of this inventionis to pro 10 to the reservoir; '
'
>
vide a. highly efficient system of the character l ‘
Fig.`3 is a semi-schematic view corresponding
described wherein a hydraulic motor or driven
unit having a novel arrangement of valves char
acterized by thermal expansion, thermal con
traction and hydraulic locking functions is corn
bined in such manner with a hand operated hy
draulic pump unit including a source of supply
of hydraulic fluid, and a novel arrangement of
thermal expansion and thermal contraction re
to Figs. 1 and 2 but showing the contraction
relief valve as when opened due to contraction of
the fluid in the system, to allow a compensating
amount of fiuidto be induced into the system
from the reservoir.
‘
'
Referring to thefdrawing~ more specifically, it
is seen that a hydraulic-control means and system
embodying the inventionV hereof generally in
lief valves coacting with corresponding valves in 20 cludes a motor unit A, a drive or power transmis'
the motorI unit, that under all temperature and
sion means B operated thereby to actuate an air
operating conditions the motor unit will instantly
plane engine throttle or other airplane control,
and exactly respond to a corresponding operation
not shown, a manually operable master or pump
of thepump unit to the end that a greater nicety
unit C, fluid transmission lines D and E opera
and accuracy of control will be assured;
'
Another object of my invention is to provide 'a
hydraulic control system of the character de
scribed in which the motor and pump units'are
similarly constructed of but few parts, certain
of which are interchangeable to facilitate vre
placement and servicing operations, said units
being exceptionally small and compact and light
as to weight and subject to ready installation in
small compass as is highly desirable in aircraft,
25 tively connecting the pump and» motor units, a
manually operable means F for actuating the
pump unit; and a reservoir G yconnected with the
pump unit for thermal relief compensation pur
poses responsive` to the automatic. operation of
30 valvular means coacting in said motor and pump
units under temperature variations in the system
to maintain the proper volume of fluid therein,
as willbe hereinafter-,more fully described.
As here provided the'motor unit A comprises a
also characterized by “built-in" control and 35 hydraulic cylindery Ivr in which a piston 2 is recip
thermal relief valves in an arrangement which
rocally mountedand- operatively'connected by
assures the desired temperature compensation
means of a pistonrod 3 with the power transmis
sion or drive means B; -Bleed ports 4v are pro
vided adjacenttlie 'ends‘of this cylinder and are
and synchronization of the two units.
Yet another object of this invention is to pro
.
~
vide in a system such as describeda motor unit 40 closedï by mean‘smof zp'l'ugs` 5.
wherein two valves serve as a hydraulic locking
Associatedlwithßthe cylinder I is a body mem,ber 6 having fluid transmission ports l and 8
means, as return valves and also as automatic
opening on an outer facek thereof andv connected,
thermal contraction relief yvalves in coaction with
to the lines D and E respectively. Leading from
thermal contraction relief valves in the pump
45 the ports 'I and 8 through the body member 6 into
unit, to the end that the number of valves, unit
parts, the weight as Well as the cost of the units
are materially reduced and the system therefore
greatly simplified and rendered more reliable of
performance. y
'
With the foregoing objects in> view, together
with such other objects and advantages as'may
subsequently appear, the invention resides in the
parts and ‘in the combination, construction ,and
opposite ends of lthecylinder I are ,cylinder ports »
9 and I0 affording-the transmission of pressure
fluid to‘the -cylinder Vandthe discharge of return
fluid from the motorunit to the ypump unit, »also
50 a thermal compensation flow of fluid to and from
said cylinder.
¿
.
'
-
- Provided intermediate the ends of the cylinder
ports 9 and IIl'are valveseats I I for spring loaded
check valves I2f'and I3 arranged to seat in a
arrangement of parts hereinafter described and 55 direction towardfthefports 1 and 8 so as to hy
2,410,978
4
a pump piston 25 which is subject to manual
operation in either direction by means of the op
draullcally lock the piston 2 to maintain it in
any position to which it is moved. These valves
are adapted to be unseated by the operating fluid
pressure transmitted through the ports 1 and 8,
and will also be opened when thermal contraction
erating means F in the form of a lever 26 pivoted
as at 21 on a bracket 28 on the cylinder 22.
Associated with the cylinder 22 is a. pump unit
body member 29 having a reservoir port 3|! con
of the fluid in the system takes place as will be
nected to the reservoir G by means of a line 3l.
hereinafter more 'fully described.
.
,
Extending thrOugh the body member- 29 from the
As a means for controlling the valves I2 an
ends of the cylinder 22 to the reservoir port 30
I3. a valve actuating piston I4 is reciprocally
are contraction relief ports 32. Valve seats 33
mounted in a cylinder portion I5 provided in the 10 for spring loaded check valves 34 are provided
body member 6. This cylinder portion has end
ports I6 and I1 opening into the cylinder ports
9 and I0 at points between thervalve seats Il and
in the ports 32 at points spaced inwardly from
the juncture of the ports 30 and 32, the valves
the ports 1 and 8.
reservoir port 30 and thereby being seated by
being arranged to seat in a direction toward the
. »
The valve actuating piston I4 is provided with 15 the pressure of the operating fluid transmitted
rod-like valve actuating members I2' and I3’
from the cylinder 22 through the ports 32. The
extending from opposite sides thereof through
springs 35 for the valves 34 are of such tension
the end ports I6 and I1 for engaging and unseat
that when thermal contraction of the fluid in the
lng the valves I2 and I3. The valve actuating
system beyond a predetermined extent takes
piston I4 and members I2'` and I3' thereon are 20 place, the valves 34 will open and a volume com
arranged so that normally the `_valves I2 and I3
pensating amount of fluid from the reservoir G
are seated, but when pressure fluid is transmitted
will be induced into the system, the valves I2
from the pump unit C, through one of the lines
and I3 in the motor unit opening at this time to
D and E, for example line `l?, the piston I4 is
allow for similar volume compensation in the
moved to the left causing member I2' to open 25
motor
unit.
valve I2, while the pressure of the operating
Also provided in the pump unit body member
fluid opens valve I3. Fluid pressure transmitted
29 are thermal expansion relief ports 36 which
past the valve I3 in the cylinder port IIl is effec
are arranged to communicate the reservoir port
tive in the cylinder I to move the piston 2 to the
with the ends of the cylinder 22 through por
left, while return fluid from the cylinder I is dis 30 tions of the relief ports 32, the ports 36 by-pass
charged through the port 9 past the open valve
ing the valves 34. In the expansion relief ports
I2 into line D and back to the pump unit C.
Upon cessation of transmission of pressure fluid
through line E, the movement of the motor pis
ton 2 ceases and the valve actuating piston as
sumes its neutral position allowing valve I2 to
close; valve I3 having closed with the cessation
36 are valve seats 31 for spring loaded check
valves 38 arranged to seat toward the cylinder
35 22 and to unseat toward the reservoir port. The
spring means 39 for seating _the valves 38 exerts
a force greater than the pressure ofthe operat
ing fluid derived by manipulation'V of the pump
piston, but will yield and allow the expansion re
of transmission of operating pres/sure. With both
valves thus closed the motor pistón 2 is hydrau
lief valves 38 to open when the fluid in the sys
tem under thermal expansion exceeds a` prede
lically locked against >movement and the airplane
control operated thereby‘ls therefore maintained
in the position into which it, is moved by the
motor unit. The piston 2 of the driven unit is
always locked in a position corresponding to that
which the driving piston 25.occupies at any given
time. Therefore the operator knows that the
operated airplane control' occupies a position cor
responding to that to which he has adjusted
the lever 26.
.
'
Built into the motor unit A is a thermal ex
pension compensating means coacting with simi
termined working pressure derived fromV the
pump unit, thereby relieving to the reservoir G
excess volume resulting from such thermal ex
pansion.
The expansion relief valves I9 in the motor
unit open substantially simultaneously with the
opening of the expansion relief valves 38 in the
pump unit, thereby making the desired expansion
50 compensation in the two units and the lines D
and E connected thereto.
lar means in the pump unit C and comprising
thermal expansion relief .ports I8 and spring
loaded expansion relief valves I9. The relief
With reference to Fig. 1 lt is seen that my con
trol system is in normal condition as when no
thermal expansion or contraction is taking place
and the pump and motor units are at rest with
ports I8 extend in the body member I so as to 55 the motor unit hydraulically locked by reason of
by-pass fluid under thermal expansion from the
the valves I2 and I3 therein being closed to the
ends of the motor cylinder I around the valves
outlet of fluid from the cylinder I. When the
I2 and I3 into the fluid transmission ports 1 and
system is in this condition it is apparent that
8. Valve seats 20 are provided inthe expansion
the operator may move the pump piston in either
relief ports I5 so that the valves. I9 -will seat in 60 direction to direct operating pressure to move
a, direction toward the cylinder I, beingv seated
the motor piston in correspondence to the move
by the springs 2| ltherefor. These springs have
ment of the pump piston.
a tension such that the valves I9 will not bei
Following the predetermined movement of the
opened by the normal pressure of the operating 65 motor piston the valves I2 and I3 will close as
fluid in the ports 9 and I0, but will yield and
hereinbefore explained and effect a hydraulic
allow the valves to open whenthe pressure of
locking of the motor unit.
the fluid in ports 9 and I0 and cylinder> I, under
The reservoir G may if desired be pressurized
thermal expansion, exceeds f a predetermined
to a predetermined extent so that the fluid in
pressure beyond that requiredto'rproperly oper
the entire system will be under a pressure which
70
reduces the tendency of intaking air into the sys
ate the motor unit piston 2.
The master or pump unit C_ as here provided.
is similar tothe motor :unit A and comprises a
pump cylinder 22 having fluid transmission ports
23 and 24 at its ends `to which ports the lines
D and E are connected. In the cylinder 22 is 75
tem but does not change the thermal expansion
and contraction functions which are performed
in the same manner as hereinbefore described.
When thermal expansion of the fluid produces
2,410,978
6
a pressure beyond the normal or predetermined`
lief ports extending through said pump unit'body
pump unit working pressure, the valves I9 in the ’ '
member from the ends of said pump cylinder to
said reservoir port, spring loaded contraction
motor unit and the corresponding valves 38 inthe
pump unit open responsive to this expansion pres
relief, valves arranged to vOpen fsaid' contraction
sure, as indicated in Fig. 2, thereby relieving ex- ,
relief >portslonly responsive to said predetermined ‘
cess pressure in the system into the reservoir G.
contraction of fluid in the system Awhereby'fluld
from said source of .supply will be induced
through said reservoir port into said cylinders
and the lines therebetween, fluid yexpansion re
As shown in Fig. 3, when contraction of the
fluid in the system-takes place toa predetermined
extent as determined by the force ofthe springs
seating the valves I2 and I3 in the motor unit
andthe springs seating the valves 34 in the pump;
unit, the valves I2, I3 and 3_4 will Open thereby
4inducing into the system an amount of fluid to
compensate for the volume loss incidentfto such
contraction of the fluid.
'
It is now seen that the thermal compensating
10
lief ports in said pump unit body member `ar-V'
ranged' to'by-pass fluid around said contraction'
relief valves from saidy pump` cylinder into 'said
reservoir port; and spring loaded‘expansionv re
lief valves arranged'in the last named expansion
Ll5 relief ports to openr only when the' pressure- of ' `
provisions hereof make possible asubstantially
uniform volume and pressure in the system under
varying temperatures thereby assuring exact and
the fluid in the motor and pump units and said'
lines under thermal expansion exceeds said pre-`
determined >working pressure ofthe operating
fluid in the system.
'
.
>
‘
'
instant response of the motor unit to the pump 20
2. vIn a closed hydraulic control system, a mo
unit.
,
'
- Itor 'unit cylinder, a piston reciprocable in said
f While I have shown and described a specific
cylinder, a drive means operated by said piston,
embodiment >of my invention I do not limit my
a, body member associated with said cylinder,
cylinder ports leading through said body mem
self to the exact details of construction set forth,
and the invention embraces such changes, modi
ilcations and equivalents of the parts and their
ber from' an'outer surface thereof to’ opposite'
ends of said cylinder, valves intermediate theVK
formation and arrangement as come within the
' ends of said ports and closing toward the outer
purview ofthe appended claims.
ends of said ports to normally provide a hydraulic
I claim:
1. In a hydraulic control system, a motor unit .
cylinder, a piston reciprocable in said cylinder,
a drive means operated by.> said piston, a bodyk
member associated with said' cylinder, cylinder
lock for said piston, >springs normallyseating
said valves and yielding to allow they valves to
open responsive tov pressure of loperating fluid
transmitted to'said ports as well as when' a pre
determined thermal `contraction of the fluid in
the system takes place whereby in the latter in
stance fluid will be induced into said cylinder, a
portsfleading through said body memberfrom
an outersurface thereof to opposite ends of said
cylinder, valves intermediate the ends of said
cylinder 'portion in said body member having end
ports and closing toward the outer ends of said
ports 'opening into said cylinder ports between
ports t0 normally provide a hydraulic lock for
the outer ends of the latter and said valves; a
said piston, springs normally seating said valves
valve actuating piston movable from a neutral
and yielding to allow the valves to open yrespon 40 position into a valve actuating position responsive
sive to pressure of operating fluid transmitted
to the transmission of 4operating fluid to said cyl
to said ports, as well as when a predetermined
inder portion through either of said cylinder
thermal contraction of the fluid lin the system
ports and either of said end ports, valve actuat
takes place whereby in the latter instance fluid
ing members operating upon movement of said
will be induced into said cylinder, a cylinder por 45 valve actuating piston into an actuating position
tion in said body member having end ports open
to unseat one of said valves to allow return fluid.
ing into said- cylinder ports between the vouter
to >flow from said motor unit cylinder and one
ends of the' latter’ï‘andisaid valves, a valve actuat
of said cylinder ports, thermal expansion relief
ing piston movable from a neutral position into
ports arranged to by-pass iluid past said valves
a valve actuating position responsive to the trans 50 from'the ends of said cylinder into the outer ends
mission of operating fluid to said cylinder por- '
'of` said cylinder ports,y spring loaded expansion
tion through either of said cylinder ports and
relief valves arranged in said relief ports to lbe
,either of said end ports, valve vactuating mem- v
unseated only when the pressure of the fluid'-
bers operating upon movement of said valve ac
`under thermal expansion exceeds a predeter
. tuating piston into an actuating position to un
mined working pressure'of the fluid transmitted
.to said motor unit, a pump unit, andtwo fluid
seat one of said valves to allow return fluid to
flow from said motor unit cylinder and one of
said y cylinder ports, thermal expansion relief
ports arranged in said body member to by-pass
supply and withdrawal conduits connected with
said pump unit, one of said conduitsv communi
cating with one of saiddcylinder ports, and the
fluid around said valves from the ends of said 60 other4 of said conduits communicating with the
cylinder into the outer ends of said cylinder
other of said cylinder ports, and a source of sup
ports, spring loaded expansion relief valves ar
ply of fluid under pressure connected in said sys
ranged in said relief ports to be unseated only
tem to receive fluid therefrom and introduce
when the pressure of the fluid under thermal
fluid thereto responsive to thermal expansion and
expansion exceeds a predetermined workingpres
contraction of the fluid in the system.
sure of the fluid transmitted to said motor unit,
3. In a closed hydraulic control system, a hy
a pump unit cylinder, iluid transmission lines
draulic motor unit, a body member associated
between the ends of said pump unit cylinder and
the outer ends of said motor unit cylinder ports,
a pump piston in said pump unit, means for re
ciprocating said pump piston, a pump unit body
member associated with said pump cylinder, a
reservoir port in said pump unit body member,
.a source of supply of hydraulic fluid connected
therewith, operating ports leading through said
body member from an outer surface -thereof to
70 vsaid motor unit, valves in said ports arranged
to seat toward the outer ends of the ports to pro
vide a hydraulic lock for said motor unit,l springs
seating said valves and yielding to allow the
valves to open responsive to the pressure of op
with said reservoir port, thermal contraction re- 75 erating fluid transmitted to said operating portsv
,
2,410,978
body member from an outer surface `thereof for
conveying fluid to and from said motor unit,
valves in'said ports arranged to seat »toward the
responsive valve operating means in; said body
outer ends of said ports, springs seating ’said
member subject'to movement for unseating the 5 valves and yielding to allow the valves toppen
valve in one of the operating ports when operat
responsive 1 to the pressurey of operating fluid
ing fluid is transmitted to the other port and
transmitted to said operating ports as well as
releasing the valve in said one port upon cessa--`
when a predetermined' thermal-contraction of
tion lof the transmission of operating fluid to said
fluid takes place in they system, afluld responsive
other port, thermal expansion relief ports ar
valve-operating means in said body member sub
ranged to by-pass fluid past said valves from said 10 ject to movement‘for unseating the valve inf‘one
motor unit to the outer ends of said operating'
of said ports when operating pressure is trans
ports, spring loaded expansion relief valves ar-v
mitted
to the other port and for releasing the Y
ranged to be unseated and open said relief ports
valve in said one port upon cessation of the trans
only when the pressure ofthe fluid under ther
mission ofoperating pressure to said other port,
mal expansion exceeds the> predetermined work
thermall expansion relief ports arrangedin said`
ing pressure of the fluid transmitted to said mo-`
body member to -by-pass fluid around said valves
tor unit, a pump unit, two fluid supply and with
from- said motor unit to the outer ends of said
drawal conduits connected with said pump unit,A
operating ports, spring loaded expansion relief
one of said conduits communicatingwith one of
valves arranged in said relief ports to be unseated
said cylinder ports and the other of said- con 20 when the pressure of the fluid under thermal
duits communicating withthe other of said cyl
expansion exceeds a predetermined pressure, a
inder ports; and a source of supply of fluid under
pump unit cylinder, fluid transmission lines con
pressure connected in said system to receive fluid
necting said operating ports with said pump unit
therefrom and introduce fluid thereto responsive
cylinder, a pump unit piston in said cylinder,
to thermal expansion and contraction of the fluid 25 means for reciprocating said piston, a pump unit
in the system.
,
,
body member associated with said cylinder, a res.
as well as when, a predetermined thermal con
traction of fluid takes placeV in the system, a fluid"
4. In a closed hydraulic control system, a m0
ervoir port in said pump unit body member, a res
tor unit cylinder, a, piston reciproca-ble in said
ervoir fluid under a predetermined pressure con
cylinder, a drive means operated by said piston,
nected to said reservoir port and applying pres
a body member associated with said cylinder, 30 sure to the fluidthroughout the system, thermal
cylinder ports leading through said body member
contraction relief ports in said pump unit body
from an outer surface thereof to opposite ends
member affording communication between said
of said cylinder, valves intermediate the ends
cylinder and said reservoir port, spring loaded
of said ports and closing toward the outerends
contraction relief valves arranged in the last
of said ports to normally provide a hydraulic lock 35 named contraction ports to open responsive to
for said piston, springs normally seating said
a predetermined contraction of fluid in the sys
valves and yielding to` allow the valves to open
tem, fluid expansion relief ports in said pump
responsive to pressure of operating fluid trans
unit body member for by-passlng fluid around
mitted to said ports as well as when a predeter
the contraction relief valves in said pump unit
mined thermal contraction of the fluid in the 40 body member to said reservoir port, and spring
system takes place whereby in the latter instance
loaded expansion relief valves in the last named
fluid will be induced into said cylinder, a cylinder
expansion relief ports arranged to open when
portion in said body member having end ports
the pressureA of fluid in the system under ther
opening into said cylinder ports between the - mal expansion exceeds a predetermined pressure.
outer ends of the latter and said valves; a valve
6. In a closed hydraulic system of the kind de
actuating piston movable from a neutral posi
scribed, a hydraulic motor unit comprising a dou
tion into a valve actuating position responsive
ble -acting piston, a hydraulic pump unit com
to the transmission of operating fluid lto said cyl
prising a double acting piston, conduit lines for
inder portion through either of said cylinder 50 transmitting fluid under pressure from the pump
ports and either of said end ports, valve actuat
unit to the motor unit to~operate the piston cf
ing members operating upon movement of said
the latter in either direction, a closed fluid pres
valveactuating piston into actuating positions
sure supplyi reservoir in fluid communication
to unseat one or the` other of said valves to allow
with said system, a set of two-way thermal relief
return fluid to flow from said motor unit cylin
between said reservoir and both ends of
der and one or the other of said cylinder ports, 55 valves
one of said cylinders and a set of two Way ther
thermal expansion relief ports for by-passing
mal relief valves between both ends of the other
fluid past one or the other of said' valves from
of said cylinders and the‘conduits connected
said cylinder to the outer end of one or the other
of said cylinder ports, spring loaded expansion
7. In a closed-circuit hydraulic motion-trans
relief valves aranged in said expansion relief port 00 mitting
apparatus, a driving unit comprising a
to be unseated only when pressure of the system
closed cylinder having a double acting piston
fluid under thermal expansion exceeds a prede
mounted for reciprpcation therein, a driven unit
termined pressure, a pump unit, two fluid supply
having a corresponding cylinder and piston, a
and withdrawal conduits connected with said 65 pair of conduits connecting the ends of the driv
pump unit, one of said conduits communicating
thereto.
`
`
ing unit cylinder with the ends of the driven‘unit
with one of said cylinder ports, and the other
cylinder, a reservoir connected with both ends
of said conduits communicating with the other
of one of said cylinders and utilizable to impose
of said cylinder ports; and a source of supply
a predetermined pressure on said apparatus, a
of iluid under pressure connected in said system
pressure responsive locking valve structure be»
to receive fluid therefrom and introduce fluid 70 tween said units constructed and arranged to
thereto responsive to thermal expansion and con
lockvthe driven piston at a position correspond
traction of the fluid in the system.
ing to that which the driving piston occupies-at
5. In a closed hydraulic control system, a hy
any given time, a two-way thermal relief valve
draulic motor unit, a body member associated 75 mechanism between said reservoir and one of
therewith, operating ports leading through the
2,410,973
said units, and a. two-way thermal relief valve
mechanism between said units.
8. In a closed hydraulic system of the kind
described, a hydraulic motor unit comprising
a cylinder containing a double acting piston, a
hydraulic pump unit comprising a cylinder con 5
taining a double acting piston, conduits connect
ing the ends of said pump unit cylinders with
the corresponding ends of said motor unit cyl
9. In hydraulic apparatus, a source of hy
draulic pressure, a pair of conduits leading from
said source of pressure to opposite ends,of a dou
ble acting hydraulic motor, means to control vde
livery of said hydraulic pressure to said conduits,
a locking valve means comprising a, pair of op
positely disposed valves and an actuating element
therefor interposed between said conduits and
said motor and operative normally to prevent
inder. a closed ñuid pressure supply reservoir 10
movement of said motor in theabsence of the
connected to said conduits, a set of two-way
application of operating pressure through said
thermal relief valves between said reservoir and
conduits
and simultaneously operative to accom
both ends of said pump cylinder and a set of
modate fluid flow incident to thermal contrac
two-way thermal relief valves between both ends
of the other of said cylinders and the conduits 15 tion of the fluid in said motor, and an oppositely
disposed thermal relief valve associated with
connected to them, and a locking valve struc
each of said locking valves constructed and ar
ture arranged to lock the piston in adjusted po
ranged to accommodate fluid ñow incident to the
sition in said other cylinder, said locking valve
thermal expansion of fluid in said motor.
structure including said last named set of ther
mal relief valves.
20
JOHN WILLIAM KELLY.
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