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Jan. 7, 1947. _
w, A, FLETCHER
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2,413,757
VALVE
Filed Jan. 5, 1944
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INVENTOR
%4%
BY
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114
WMH’”
ATTORN EYb
Patented Jan. 7, 1947
2,413,752
UNITED‘ STATES PATENT OFFICEVALVE
William A. Fletcher, Anderson, Ind., assignor to
General Motors Corporation, Detroit, Mich., a
corporation of Delaware
Application January 5, 1944, Serial No. 517,080
5 Claims. . .(Cl. 137-'—144)
1
2
.
This invention relates to a valve unit for con
trolling ?uid pressure in- an hydraulic servo-sys
tem which operates, for example, to control the
course of an airplane.
" > rection of the position of the steering apparatus
_ required to maintain the ‘course.
Further objects and advantages of the present
invention will be apparent from the following
'
It'is an object of the present invention to con
trol ?uid pressure in accordance with the value
,_
of a controlling force of relatively small mag
nitude, for example, the force of attraction upon a
movable armature of an electromagnet respon
sive to variations in voltages of small magnitude 10
Fig. 1 is‘ ahydraulic diagram including sec
tional views of valves embodying the present in
such as used in the automatic-pilot system of air- '
vention.
description, reference being had to ,the accom
panying drawings wherein a preferred embodi-_
ment of the present invention is clearly shown.
In the drawings:
,
Fig. 2 is a top view of the electrically operated
plane control. In the disclosed embodiment of
valve unit ‘embodying the present invention.
the invention, this object is accomplished by the
Fig. 3 is a view taken in the direction of ar
cooperation of a main valve for controlling the
discharge of ?uid from the high pressure line to 15 row 3 of Fig. 2.
Fig. 4 is a sectional view on line 4-4 of Fig. 3.
Fig. 5 is a view drawn to a- larger scale than
the low pressure side of the hydraulic system, an
hydraulic relay having a cylinder which receives
Figs. 2, 3 and 4 and is in part a side view looking
pressure ?uid from the high pressure line, a pis
in ‘the direction of arrow 5 of Fig. 4 and‘ is in
ton within the cylinder for applying ?uid pres
sure to force the main valve toward its seat, and 20 part a sectional view taken on line 5A-5A and
on line 5B-5B of Fig. 4.
.
-_
means for regulating the pressure in the cylin-J
Referring to Fig. 5, a base It) is provided with
der in accordance with the magnitude of the con
cylindrical portions ll each receiving a valve seat
trolling force and comprising a duct connecting
member l2 having a central bore l3. Body I0 is
the cylinder with the low pressure side and pass
ing through a pilot valve seat provided by the 25 provided with apertured ears l4‘ each for receiv
ing a screw not shown by which the body 10 may
main valve, a pilot valve whose movement toward
be secured to a plate [5, Fig. 1.
the pilot valve seat is opposed by the pressure of
Each cylindrical portion ll receives a valve
the ?uid escaping through the pilot valve seat,
guide l6 which receives a valve l'l. Each valve H
and means for applying to the pilot valve, a force
for urging it toward its seat. As the controlling 30 has a conically tapered lower end 18 adapted" to
_ engage the edge I!) of the valve seat 12. The valve
force is applied to urge the pilot valve toward its
seat, the pressure in the cylinder increases and . l1 has a portion 20 of reduced diameter providing
a shoulder at 2|. A passage 22 extends upwardly
the main valve approaches its seat to increase the
' thru the center of the valve l1 and connects with
pressure in the high-pressure line. The control
ling force continues to move the pilot valve with 35 a passage 23 terminating at the shoulder 2|, thus
providing communication between the exterior
the main valve until equilibrium status is reached
of the valve I1 and a chamber 24 within the valve
wherein the fluid pressure upon the pilot valve is
guide l6 which provides the cylinder with which ,
_ balanced by the controlling force and the weight
of the pilot valve and the ?uid pressure acting
upon the piston to ‘close the main valve balances
the ?uid pressure tending to open the main valve.
Thus the line pressure maintained by the main
the valve l'l cooperates as a piston. Valve 11 has .
40 another portion 25 of reduced diameter having
a sliding ?t within an aperture in the upper wall
of the valve guide I6. The portion 25 is provided
with a side passage 26 connecting with the .v'ver
valve depends upon the magnitude of the con
tical passage 21 which terminates at a conical
trolling force applied to move the pilot valve to 45 valve
seat 28 ‘for receiving the spherical lower
ward its seat.
end of a valve rod 29. To facilitate further-def
The present valve unit is useful particularlyin
scription, certain parts such as l2,.; l3, l1, 24-?and
an automatic-pilot system which provides a sig
29 which are in the left half of Fig. 5 are given
. nal or controlling force whose magnitude depends
the a?ix l and those in the right half of Fig.1.’: are
on the amount of deviation from a predetermined 50
course. The present valve unit provides for con
given the ailix r.
trol of operating pressure in accordance with the
magnitude of the signal. Therefore the hy
draulic servo-apparatus performs in accordance
with the magnitude of the signal to make the cor- 65
plate 3| is provided with apertures each for re-'
ceiving an annular ?ange I Go provided by the up
per wall of the valve guide [6 which ‘?ange sur
rounds the portion‘ 25 of the valve I 'l.- Plate 3| is
1
'
"i’i'w .
Screws 30 secure a plate 3| to the body I0.‘ 5 The
2,413,757
I
.
3
seat, the pressure in the cylinders 96 and 91 will
provided with a vertical ?ange 33 which provides
a mounting pad 34.
be equalized and there will be no movement of
the rack IIII and the shaft I93. The valves I1
-
Screws 35 and 36 secured to the mounting
plate 3| the laminated ‘core 49 of an electromag
net device which controls the rods 29. The core
remain in balanced position so long as the elec
tr'o-magnetic effects of the two coils H are the
same, the armature 59 being in symmetrical posi
49 includes a horizontal base 4I, two vertically
extending side-branches“ and a central branch
43. The branches 42 provide arcuate pole faces
44 concentric with the axis of. a shaft 45 which,
as'shown in Fig. 4, is supported by ball bearings
tion, that is, with its arm 58 being vertically lo
cated and with its arm 51 horizontally located as
shown in Fig. 5. The electrical apparatus for
10
46, retained by plates 41 screw threadedly engag
ing a frame 48 secured by screws 49 (Fig. 5) to
controlling the amount of current ?owing in the
coils ‘II is not shown, but it will be understood
by those skilled in the art of automatic controls
for aircraft that this apparatus operates, when
the core branches 42. Each screw 49 passes
through a hole 50 in the frame 48 said hole being
the airplane departs from a predetermined course,
substantially larger than the threaded portion of
tromagnet and decrease the magnetism of the
other electro-magnet as will result in movement
of the shaft I93 to such an extent that the plane
the screw.- Screw 49 passes through a non-mag
netizable spacer block 5I and threaded engages
a tapped hole 52 in a core branch 42.
_
‘
to cause such increase of magnetism of one elec
will be brought back into its course.
4
Normally when the electromagnetic effects of
20
laminated T-shaped armature 55 having side
magnets H are equal, the armature 56 will be
The shaft 45 is connected by pin 55 ‘with a
arms 51 and a downwardly extending arm 58 hav
ing an arcuate pole face 59 in close proximity
located with its arm 51 horizontal (Fig. 5) and
the valves I11 and I1r will be located the same
to an arcuate pole face 69 provided by the core
distance above their valve seats I21 and I21‘ as
arm 43, the pole faces 59 and 69 being concentric
shown in Figs. 1 and 5. The rods 29 exert equal
with the shaft 45._ The pole faces (H of the side
forces upon their seats 28 due to their own
arms 51 which are located in close proximity to
weights which are equal. The screws 84 are so
the pole faces 44 of the core branches 42 are con
adjusted as to provide the proper opening of the
centric with the axis of shaft 45.“ The gap be
valves I11 and I11‘ when the magnet coils H are
tween each of the pole faces 44 and the adja
in balance. Normally the flow of pressure ?uid
cent pole face 6| may be varied by turning a screw 30 through the high pressure inlets I3 to the low
62 threadedly received by a lug 63 provided by
pressure outlets H3 is equal, and valves I1 are
the frame 48. To make the adjustment the screw
located in the same distance above the seats I9
49 is loosened so as to permit motion between the
as shown in» Figs. land 5. Some pressure ?uid
block SI and the core 42 relative to the frame-48.
?ows through each chain of valve passages 22,
The screw 62 is turned inorder to push the block
23, 25, 21 and out through‘ a valve seat 28 under
5I and consequently the core branch 42 toward
neath the lower end of a rod '29. ‘When oil
the shaft 45 to reduce the gap between pole faces
is being pumped there is pressure upon the lower
44 and GI and the screw 62 maybe turned in the
ends of the rods su?icient to 'raise them up
opposite direction to permit the core 42 to move
against the screws 84,. and the valves I11 and HT
away from the shaft 45 due to the resiliency of 40 are elevated above their seats a distance sufficient
the core. After the adjustment of the gaphas
to give a certain low balanced pressure. The un
been made, the screw 62 is secured by lock nut
interrupted circulation of oil through passages
64 cooperating with a lock-washer 65, and the
22, 23, 2G, 21 provides for scavenging any‘ par
screw 49 is tightened.
'
I
.' ticles of dirt which might be present in the oil
‘Each core branch 42 is surrounded by a non
conducting spool 19 upon which an electro-mag
net coil 1 I is ‘wound. The spool 10 is urged against
the core base M by leaf spring 13 carrying a stud
14 received by a recess in lug 63 of a frame 48.
Pin 80 secures to shaft 45 the hub 8I, (Fig. 4)
of a walking beam lever 82, each end of which is
provided with a tubular portion 83 for receiving
theupper end of a valve rod 29 and for threadedly
in the cylinder 24, and prevents the accumula
tion of dirt particles in the cylinder. The total
pressure force acting upwardly on the valves I1
is balanced by the total pressure forcewithin the
cylinders 24 acting downwardly upon the valves
I1. The device (not shown) which is responsive
to deviation of the airplane from a predetermined
course will cause .current in one magnet H to
increase and the current in the other magnet
H to decrease depending on the direction of
deviation. Assuming that the left hand magnet
1I1 receives more current than the right hand
receiving a screw 84 for engaging the valve rod
- 29.‘ By turning the screw 84 the relation between
‘ the valve rod 29, the valve I1 and the lever 82
is-adjusted. The screw 84 is secured in the de
sired positions of adjustment by lock nut 85.
'
Referring to Fig. 1, a valve unit is submerged
. below the level 9I of pressure ?uid contained in a
magnet 1Ir, armature 56 will rotate slightly
counterclockwise to cause rod 291 to move down
Ill to increase the restriction between the lower end
Y. ‘tank v99. Submerged motor driven gear pumps
"':~~92:>and 93. force pressure fluid from the tank
of rod 291 and the adjacent valve seat 28. The
pressure in cylinder 241 increases and valve I11
moves down to increasev the restriction between
the lower end of valve I11 and the adjacent seat
65 I9, and thereby to increase the pressure in pas
sage I31. As valv'e I11 moves downarmature 56
zI??eproviding a rack IIlI meshing with a
moves counterclockwise to move the rod 291
through passages 94 and 95 vconnected respective
ly='-with cylinders 96 and 91 of hydraulic servo
motor which include pistons 99 and 99 connected
'
2 .fdndriving a shaft I03 for operating the
deviceet‘obe controlled which may be, for ex
<.>.-: ample;f”the steering apparatus of an airplane.
The passages 94 and 95 are connected by passages
I94 and I05 respectively with ports I31 and I31
~ provided by the left end valve seat I21 and the
.
right hand valve seat I21". When the valves I1 1
are in balanced portion as shown in Fig. 1, each
valve being elevated the same distance from its 75
againstthe pressure of fluid escaping at the ad
jacent seat 28. Equilibrium is established when
the total pressure, acting upwardly on the rod
291 equals the weight of the rod 291 plus the force
acting downwardly on the rod 291, which force is
due to the differential of the vmagnetic effects of
the magnet coils H. The greater this differen
tial, the. greater will be the total“ ?uid pressure
ane-n7 ‘
6
in the cylinder 24! to force the valve I'll down
against an equal total ?uid pressure acting up
wardly through the passage I31. Thus for each
.value of force applied magnetically to the rod 291,
to vary is counteracted by a movement of valve
Ill into a position of equilibrium such that the
pressure in passage I31 will remain constant so
‘ long as themagnetic di?erential’ioi the coils ‘Ill
there is' a corresponding value of total ?uid pres
sure in the passage I31.
As valve I'll moves toward closed position, valve
l'lr moves upwardly to e?ect a reduction in pres
sure in the passage I31‘. As pressure in cylin
and 1 Ir remains constant, regardless'of the quan
tity of ?uid moving from the, pump 92.
Obviously. the foregoing applies to the con
trol of pressure in passage l3r. Because the con
trol valves are not affected by rate of oil circula
' der 96 (Fig. 1) increases, pressure in- cylinder 10 tion, automatic control of the steering of the
91 decreases. Pistons 98 and‘ 99 move right to
plane is very sensitive to deviation from a pre
move the steering apparatus in such direction as
determined course.
'
to cause the airplane to return to the predeter
While the embodiment'of the present invention ‘
mined course. As the deviation frompredeter-l
as herein disclosed, constitutes a preferred form,
mined course diminishes, the current in the coil 15 it is ‘to be understood that other forms might be
,‘lll diminishes while the current in coil ‘Hr in
adopted, all coming within the scope of the claims
creases. Valve ill moves up toward the position .
which follow.
_
-
shown in Fig. 5 while valve "1' moves down to
What is claimed is as follows:
ward the position shown in Fig. 5. Pressure in
1. A valve unit for‘controlling ?uid pressure
cylinder 91 increases while pressure in cylinder 20 comprising, in combination, a pressure ?uid re
96 decreases. When these pressures are equal,
ceiving duct providing a valve seat, a main pres- '
movement of the pistons 98 and 99 ceases. When
sure relief valve cooperating with the seat for
the course of the plane has been restored to the '
controlling the discharge of ?uid from the duct,
predetermined course, the magnetic e?’ects of the
an hydraulic relay controlling the main valve and
coils ‘Ill and Hr are equal and the armature 5B is 25 including relatively movable cylinder and pis
, in normal position as shown in Figs. 3 and 5.
ton members, one of which is ?xed and the other
of which is connected with the main valve, a
The pistons remain in the position to the right
of the symmetrical positions shown in Fig; 1 so
long as the steering apparatus is adjusted to
.maintain the course. If the condition which re
quired movement of thepistons to the right of
symmetrical position diminishes in e?ect, the
adjustment of the steering apparatus would be
duct connecting the ?rst duct with the cylinder,
a duct for the discharge of ?uid from the cylin
30 der, means for controlling the discharge of ?uid
from the cylinder. through the second duct and
including a pilot valve 'seat movable with the
‘ main valve and a pilot valve cooperating with
'the pilot valve seat and receiving upon its face
35 the pressure of ?uid escaping from the cylinder
for urging the pilot valve away from its seat
and means for applying a controlling force to
the pilot valve to urge it toward its seat, where
greater than required to eifect the deviation from
course and there will be a deviation in the op
posite direction. When this occurs, coil ‘Hr will
receive more current than coil ‘Ill; and valve Ilr
will close while yalve I'll opens. Then the pres
sure in cylinder 91 exceeds‘ the pressure in cyl
by in equilibrium status, the pilot valve is in
inder 96 and the pistons move left until the steer 40 balance between the force urgingethe pilot valve
ing apparatus is so adjusted as to maintain the i
toward'its seat and the pressure ?uid force urg
predetermined course.
ing the pilot valve away from its seat and where
‘While the pistons 98 and 99 are moving in either -
by, the main valve is in balance between cylin-_
direction, there will be a tendency for a change
der pressure and fluid pressure acting against the
in operating pressure in cylinders 95 and 91, while Cl face of the main valve.
_
I
the magnetic di?erential remains constant. To
2. A valve unit for controlling a ?uid pressure
offset this the valves I ll and HT are automatical
in accordance with a controlling force and com
ly moved into positions for maintaining the pres- _
prising,
in combination, a pressure ?uid receiv
sure called for by the magnetic effects of the mag
ing duct, 2. control element, apparatus for main~
nets ‘HZ and 1|r. Assuming that the pressure 50 taining the control element in a normal posi
in passage I31 tends to increase above a certain
tion to obtain a corresponding normal ?uid pres
value corresponding to a certain magnetic dif
sure, in the duct and sensitive to the operation of
ferential, the pressure in cylinder 241 begins to in
a controlling force demanding pressure increase
crease, and the pressure acting on the lower end
for moving the element to obtain a pressure in
- of rod 291 begins to exceedthe total of the force 55 the duct corresponding to the magnitude of the
of gravity on the rod and the magnetically derived
controlling force, a main valve seat provided by
force acting thereon._ The rod 281 begins mov
the duct through which pressure ?uid can be dis
ing upwardly and the armature 56 begins to move
clockwise. Rod 2,91 begins moving up to decrease
' charged from the duct a member providing at
the restriction :at the adjacent seat 28, thereby
60 valve seat and providing, at the other end remote
reducing the pressure in cylinder 24!. Valve ill
moves up to reduce the pressure in passage _l3_l.
one end a main valve cooperating'with the main
from the main valve seat, a pilot valve seat, and
providing, intermediate its ends, a piston, a cyl
If the pressure in passage I31 tends to fall below
inder receiving the piston and guiding the move
the value which corresponds to a certain mag
ments of the valve, a‘ duct connecting the ?rst
netic differential, the pressure in cylinder 24! be
' duct with the cylinder whereby ?uid'pressure is
gins to decrease, and the pressure acting on the
applied to the piston to urge the main valve to
lower end of rod 291 begins to'fall below the total
ward its seat in opposition to ?uid pressure in
of the force of gravity and the magnetically de
the ?rst duct acting upon the main valve, a duct
rived force ‘acting thereon. The rod 291 begins ' providing for discharge of pressure ?uid from
moving-down and the armature 58 follows-it by a 70 the cylinder and terminating at the pilot valve
counterclockwise movement. The restriction at
seat, and a pilot valve positioned between the
seat 28 increases to cause pressure in cylinder 241
pilot valve seat and the control element and
to increase and to cause downward movement of ,
actuated away from its seat by the pressure of
valve I'll to increase pressure in passage I31.
?uid escaping through the seat from the cylin
Thus the tendency of the pressure in passage I31 75 der, the control element limiting said ?uid pres
" 8,418,767
,
sure actuated movement or the pilot valve away
from its seat thereby controlling the ?uid pres
sure acting upon‘jthe piston to urge the main
valve toward its seat whereby a certain pressure
is normally maintained in the ?rst duct when the
control element is in its normal position, and
whereby ‘a higher‘ pressure is maintained in the
'
8
-
sure in the ?rst duct to a certain normal value,
means for applying‘ a force to move the control
element to- decrease the gap between the pilot '
valve and its seat in order to cause the pres
sure‘ in the cylinder to increase whereby the
main valve moves toward its seat to increase the
pressure in the ?rst duct, movement of the con
trol element along with the pilot valve and main
valve continuing until equilibrium is established
controlling force urging the pilot valve toward
10 between the control force acting upon the control
its seat.’
element to‘ urge the pilot valve toward its seat,
3. A valve unit for controlling ?uid pressure
and the force of the pressure or the ?uid escap
in‘ accordance with control by opposing forces
ing from the cylinder through thepilot valve seat
and comprising, in combination, a pressure ?uid
and acting upon the pilot valve and between the
?rst duct depending on the magnitude of the
receiving duct a control element, apparatus sensi
pressure of the ?uid in the cylinder acting upon
tive to the action of two opposing forces for 15 the main valve to urge it toward its seat and the
maintaining the control element in a normal posi
pressure of the ?uid at the main valve seat act
. tion when the forces are equal and for moving the
ing upon the main valve, whereby a pressure
element from normal position when the forces
in the ?rst duct is established depending upon the
are unequal, a main valve seat provided by the
magnitude of the controlling force.
duct through which pressure ?uid can be dis 20
5. A valve unit for controlling ?uid pres
charged from the duct, a member providing at
sure in accordance with a controlling tome and
one end a main valve cooperating with the main
comprising, in combination, a pressure ?uid re
valve seat and providing, at the other end remote
ceiving duct a main valve seat provided by the
from the main valve seat, a pilot valve seat, and
duct for the discharge of pressure ?uid, a main
_ providing, intermediate its ends, a piston, a cyl 25 valve cooperating with the seat to limit the ?ow
inder receiving the piston and guiding the move
of ?uid therethrough, means for urging the main
ment of the valve, a duct connecting the ?rst
valve toward its seat and comprising a piston
duct with the cylinder whereby ?uid pressure is
provided by the. main valve and a cylinder receiv
applied to the piston to urge the main valve
ing the piston, a duct connecting the ?rst duct
30
toward its seat in opposition to ?uid‘ pressure
with the cylinder, a duct through the valve com
acting upon the main valve, a duct providing ~ municating with the cylinder and terminating in
for the discharge of pressure ?uid from the cyl
‘ a pilot valve seat at the end of said member re
inder and terminating at the pilot valve seat, and
mote from the ‘main valve portion, a pilot valve
a pilot valve positioned between the pilot valve.
facing said seat, a control element for'the pilot
35
seat and the control element and actuated away
valve normally, located so as to permit limited
from its seat by the pressure of ?uid escaping '
movement of the pilot'valve away from its seat
through the seat of the cylinder, the control ele
due to the pressure of the ?uid escaping from the
ment limiting said ?uid pressure actuated move
vcylinder through the pilot valve seat, thereby
ment of the pilot valve away from its seat there
by controlling the ?uid pressure acting upon the 40 limiting the escape of ?uid from the cylinder so
that a pressure is maintained therein such as to
piston to urge the main. valve toward its seat
, cause the main valve to‘ be located in a position
whereby a certain pressure is normally main
permitting such discharge through the main
tained in the ?rst duct when the control element
valve seat as to limit the pressure in the ?rst
is in its normal position, and whereby a‘higher
duct to a certain normal value, means for posi
pressure is maintained in the ?rst duct depend 45 tioning
the control element and sensitive to two
ing on the magnitude of the force differentia
urging the pilot valve toward its seat.
>
4. A valve unit for controlling ?uid pressure '
“ opposing forces which, when equal, cause the
‘in accordance with a controlling force and com
prising, in combination, a pressure ?uid receiv
ing duct, a main valve seat provided by .the duct
for the discharge of pressure ‘?uid, a main valve
cooperating with the seat to limit the ?ow of.
?uid therethrough, means for urging the main
valve toward its seat and comprising a piston
provided by the main valve and a cylinder receiv
ing the piston, a duct connecting the ?rst duct
with the cylinder, a duct through the valve com
municating with the cylinder and terminating
in a pilot valve seat at the end of said ,member
remote from the main valve portion, a pilot valve
facing said pilot valve seat, a control element for
the pilot valve normally located so as to permit
limited movement of the pilot valve awayfrorn
its seat due to the pressure of the ?uid escap
, ing from the cylinder throughthe pilot valve
seat, thereby limiting the escape of ?uid from
the cylinder so that a pressure is maintained
therein such as to cause the" main valve to be
located in‘ a position permitting such discharge 70
through the main valve seat as to limit the pres
control element to be-maintained in its normal
position, said means being operable in response
to a force differential demanding pressure in
crease in the ?rst duct to move the control ele
ment to decrease the gap between the pilot valve
and its seat in order to cause the pressure in
the cylinder to increase whereby the‘ main valve
moves toward its seat to increase the‘pressure
in the ?rst duct, movement of the control ele
ment‘along with the pilot valve and main valve -
continuinguntil equilibrium is established be
tween the .force differential acting upon the con
trol element to urge the pilot valve toward its
seat and the force of the pressure of the ?uid
escaping from the cylinder through the pilot
valve seat and acting upon the pilot valve and
between the pressure of the ?uid in the cylinder
acting upon the main valve to urge it toward its
seat and the pressure of the ?uid at the main
valve seat acting upon the main valve, whereby a
pressure in the ?rst duct is established depend
ing upon the magnitude of the force differential.
WILLIAM A. rmz'rcrma.
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