May 2, 1950
s, |_ MacDUFF
2,506,093
POWER STEERING APPARATUS FOR NOSE WHEELS
Filed June 5, 1947
'
Ql
2 Sheets-Sheet 1
M0
INVEN TOR.
dwarf/14cm”
M3W
A TTOENEY'
Patented May 1x950
' 2,506,093
UNITED STATES‘ PATENT OFFICE
2,506,093
POWER STEERING APPARATUS FOR NOSE
.
WHEELS
Stanley I. MacDu?', South Bend, Ind., assignor
to Bendix Aviation Corporation, South Bend,
Ind., a corporation of Delaware
Application J nine 5, 1947, Serial No. 752,737
2 Claims. (Cl. ISO-79.2)
2
This invention relates generally to steering ap
.
Valves 54 and 58 are located in conduits 50 and
paratus and more particularly to a steering
mechanism for the nose wheel of an aircraft.
‘ vOne of the important objects of the invention
resides in the provision of a power steering ap
paratus for the nose wheel of an aircraft in which
the power for steering is obtained from an open
hydraulic system and the control of this power is
through the medium of a closed hydraulic circuit.
52 respectively for manual control.
/
' The fluid motor 24 includes a cylinder 50 hav
ing a piston 60 therein, dividing the cylinder into
oppositely disposed chambers 62 and 64, con
nected to the conduits 36 and 40 respectively. A
piston rod 6| has one end ?xed to the piston 60
and its other end protruding beyond the end of
the cylinder.
An important object of the invention lies in the
‘
To control the ?ow in the open hydraulic sys
tem between the source and the motor 24 the
valve 26 is provided’. The valve comprises a body
provision of a hydraulic steering apparatus con
nected to a steered member in a manner to trans
mit motion thereto whereupon the cause produc
ing said motion is nulli?ed by the movement of
65, with a bore 86 therein. An inlet port 68, cyl
inder ports ‘It and ‘I2, and return port 14 are
15 formed in the body and open into the bore at
said member.
The above and other objects and features of
axially spaced positions therein. The bore 60 is
the invention will be apparent from the follow
recessed at 1B and/‘I8 to form valve seats 00 and
ing description of the apparatus taken in con
82 respectively on which co-axially arranged hol
nection with the accompanying drawings which
low valve members 84 and 86 normally seat to
form a part of this speci?cation, and in which:
cut off flow to the cylinder 58. A passage 88 con
Figure l exempli?es diagrammatically the ap
nects the recesses ‘I6 and 18 which are axially
paratus of the invention; and
spaced apart in the bore. A spring 90 is'inter
Figure 2 shows parts of the apparatus mounted
posed between the inner or adjacent ends of the
on a shock strut for guiding the nose wheel asso~
valve members so as to urge them in opposite di
ciated therewith.
The apparatus of Figure 1 comprises essential
ly a closed hydraulic system and an open hy
draulic system. The closed system includes a
transmitter unit I0, receiver unit I2, temperature
rections against the valve seats. For unseating
compensating mechanism I4, and conduits I8, I8,
28, and 22 interconnecting the aforementioned
30 valve members 84 and 06 respectively depending
the valve members a rod 92 is provided which ex
tends longitudinally through the bore and is
equipped with bushings 94 and 96 constituted to
engage one end of one or the other of the hollow
units and the mechanism. The open system in
cludes a fluid motor 24, valve 26, accumulator 28
for storing ?uid under pressure from a pump 30,
a ?uid reservoir 32, and a regulator valve 34 for 35
-- bypassing fluid to the reservoir when the ?uid
under pressure in the accumulator reaches a pre
determined value. One end of the motor is in
upon the direction of movement of the rod. The
rod is normally held in a position by spring 98 so
that the bushings 94 and 96 are out of engage
ment with the ends of the hollow valve members
to permit communication between the chambers
62 and 64 and the return port 14, via the interior
of the hollow valve members.
The transmitter unit I2 comprises a cylinder
communication with the accumulator through
I00
having a piston IOI therein, dividing the cyl
conduits 36 and 3t; and the other end of the 40
inder
into two chambers, one at each end thereof.
motor is in communication with the reservoir
The piston is provided with a rack I02, integral
through conduits 40 and 42. The valve 26 is in
therewith. A shaft I03 is rotatably carried by
terposed between conduits 36 and 38, and con
the cylinder in transverse relationship thereto
duits 40 and 42 respectively to control the now of
?uid to the ends of the motor. The regulator 45 and provided with gears I04 and I05 ?xed to op
posite ends of the shaft. A steering device or '
valve, which is of a type shown in my applica
wheel I06 is spllned or otherwise securely fas
tion for patent Serial Number 451,593, ?led July
tened to one end of a shaft I01 having a pinion
20, 1942, now Patent No. 2,420,890, dated May 20,
1947, is interposed between the conduit 28, and
gear I08 suitably secured thereto at the other
conduits 44 and 48, the latter conduits‘respec 50 end for driving engagement with gear I05 to
' tively, connecting the regulator valve to the out
let of pump 30 and to the conduit 42. Conduit
4i connects’the reservoir to the pump. Conduits
II and I2 interconnect the open and closed sys
tems for supplying ?uid to the latter as desired.
thereby impart reciprocal motion to piston IOI
through rotative motion of the wheel. A conduit
IIO connects the ends of the cylinder I00. A
bleed or centering valve I I2 is located in the con
duit I." for manual operation to thereby control
asoaoos '
3
ing a piston II6 reciprocally positioned therein
passage I42 but prevent ?ow in the opposite di
rection. A spring I66; is interposed between the
check valves I66 and I44 to urge them against
their seats. The manually controlled valves 64
and dividing the cylinder into two opposed cham
bers. The cylinder is formed with openings III
and 56 are arranged to normally disconnect the
closed hydraulic system from the source.
and I26 in its ends for connecting the receiver
with the transmitter through conduits I6, I8, 26
The shock strut I36 carried by an airplane,
not shown, comprises a pair of telescoping tubes
communication between the ends of cylinder I"
to permit centering the piston IUI therein.
The receiver unit includes a cylinder II4 hav
I16 and H2. The tube I'll is equipped with a
and 22. A piston rod I22 is integrally related to
the piston and extends through the ends or the 10 ?ange II4 for supporting the rotatable collar
H26. A bracket I16 is carried by the tube I'll
cylinder to thereby provide equal effective areas
for supporting the motor 24 and receiver I2. The
on the opposite sides of the piston. One end of
tube 572 is provided with a collar I'It securely
the piston rod I22 is formed at I24 to be fastened
iastened thereto against rotation. A scissors
to a lever I26. The lever is integral with a collar
I26 at one end and is rotatably carried by a shock 15 connection I86 connects the rotatable collar I24
to the collar Iii to allow for axial displacement
strut I30. The lever I26 is connected at its other
of the tubes relatlve‘to each other and to impart
end to the piston rod 6i or the ?uid motor. The
rotative movement to tube I12 about its axis to
cylinder Ht oi'the receiver is movable relative
thereby guide a nose wheel or steered member
to the piston H8. A lever Hi2 operatively ties
the cylinder Ii! and the rod t2 together so that 20 M2, carried by an axle I“ integral with tube I12.
Operation oi the apparatus is'as follows:
movement of the cylinder operates the valve
With the parts of the apparatus in the posi
members 84 and 8G. The lever use is fulcrumed
tion shown in Figure i. assume steering wheel
on a pin ltd carried by e linlr tilt supported by
M6 is rotated in a direction to move piston IOI
the valve body 65.
To compensate for pressure changes in the 25 to the left. This puts the ?uid in conduits I6
and i3, and in the upper end of the receiver
closed hydraulic system due to variation in tem
cylinder it under pressure. since the resistance
perature of the ?uid in the system the compen
, offered by the piston, which is drivably connect
sating mechanism id is provided. The temper
ed to the wheel through the aforementioned link
ature compensating mechanism per se is claimed
in my application Serial Number 704,261, filed 30 age, is greater than the resistance o?ered by the
cylinder which is operatively connected to the
Oct. 18, 1946. The mechanism includes a valve
member Mil seated in a passage Mi which com
municates conduits it and it with a reservoir
$42, the interior of which is divided, by a hex
valve rod 82, the latter is moved in response to
movement or the cylinder upwardly. That is,
upward movement of the cylinder pivots the
ible diaphragm M3, into an upper chamlmr 6418, 35 lever i232 about pin I38 which moves the rod
52 downwardly. Movement of the rod 82 down
into which air is pumped under pressure, and a
wardly carries busmng 94 with it into engage:
lower chamber I 45 in communication with pas
ment with one end of the hollow valve mem
sage I4i, whereby any change in volume of ?uid
ber 84. Initial engagement between the bush
in the system is accounted for in the reservoir
842. The valve member Mil has a stem M6 in 40 ing94 and the valve member 64 cuts o? com
munication between chamber 64 of the motor
team! with a head it'll, which is biased onto
and return port ‘id, through the hollow valve
a valve seat M8 located in the passage Hit, by
member, and continued movement of the rod
a spring hit, to thereby normally cut oil com;
downwardly unseats valve member 86 from seat
munication between the chamber its, and con
Bil to thereby counicate inlet port 58 with the
duits i5 and I8. The valve stem Mt has one
chamber 66, through passage 88 oi‘ the valve
end terminating in a passage E56 which con
body. At this
e chamber 62 is in communi
nects conduit Zll to conduit 22, to thereby sub
cation with return port ‘I4, via conduit 36, and
ject said one end of the valve stem to the fluid
the interior of hollow valve member 36. This
under pressure existing in the latter conduits.
A seal I52 encircles the valve stem to prevent 50 subjects piston 69 to a di?erential in pressure,
with the greater force acting in a direction to
leakage between the passage I50 and conduits
I6 and i8, axially along the valve stem. The ef~
move the piston downwardly, thereby rotating
the collar I28 which imparts rotation to the tube
iective annular area I54 of the valve head
I12 through the scissors connection “it, where
formed between the valve seat I48 and the valve
stem, and on which the pressure in lines I6 and 55 by wheel I82 is guided. Rotation of lever I26
in a clockwise direction by piston 60 also tends
I6 acts when the valve member is seated, is made
I46 on which the pressure in lines 20 and 22
to move receiver piston II6_ downwardly with
in the cylinder. but because of the incompressi
acts.
bility of the ?uid medium iii the ends of the
equal to the e?ective area we of the valve stem
As shown the spring H49 is selected to
exert a force on the valve member equal to sub
stantially one-half the total operating force re
cylinders II4 and I66, and, in the conduits 28
and-22, the receiver is moved downwardly as a
unit pivoting around pin I34. This returns rod
quired for the system. Actually, however, the
82 to the position shown in the ?gure. Spring
total force holding the valve member Mil on its
98 centers the rod 62 in the cylinder and the
seat is the summation of the force of spring I49
plus the pressure of the ?uid in chamber I45 65 valve member 64 is seated by'spring 90. This
arrangement provides a follow up system for cut
acting on the enlarged head I41 of the valve
ting oil the ?ow to the motor. To turn the
member. A check valve N50 is located in a pas
sage I62 which connects the chamber I45 to - nose wheel I62 back to its original position the
steering wheel is rotated in the opposite direc
conduits I6 and I8, to thereby permit the ?ow
of ?uid from the chamber to these conduits but 70 tion, that is, in a direction to cause movement
of piston IIII to the right. Since the operation
preclude ?ow in the opposite direction. The
of the apparatus in the other direction is iden
conduit 50 is connected into the passage I62 to
tical, a further discussion is believed unnecessary.
supply ?uid to the closed system when desired.
Although this invention hasbeen described in
A check valve I64 is interposed between the con
duit 60 and the passage I62 to permit flow into 75 connection with certain speci?c embodiments,
9,506,008
5
the principles are susceptible of numerous other
applications that will readily occur to persons
skilled in the art.
Having thus described the various features of
the invention, what I claim as new and desire
to secure by Letters Patent is:
I claim:
'
1. A hydraulically actuated power steering ap
paratus for an aircraft having a steering de
vice and a steered member, said apparatus com
-
6
normally closed position in which the motor is
cut oil‘ from said source to an open position
where communication-is established between the
source and the motor, a closed hydraulic system
including said steering device and a receiver unit
responsive to movement of said steering device,
a pair of conduits connecting the steering device
to said receiver unit, means providing a con
nection between the receiver unit and valve to
10 move the latter to open position to thereby con
prising a ?uid motor drivably connected to said
nect the /motor to said source, whereupon the
steered member, a source of ?uid under pressure
having a connection to said motor, a valve in
motor moves said steered member, means in the
closed hydraulic system for compensating for
pressure changes therein due to variations in
the connection, said valve shiftable from a.
normally closed position in which the motor is 15 temperature in ?uid and including a device in
cut off from said source to an open position
communication with one of said conduits and
v where communication is established between the
operative to effect release of the ?uid from said
source and the motor, a closed hydraulic sys
one conduit upon a temperature rise and force
tem including said steering device and a re
?uid thereinto upon a temperature drop, and
ceiver unit responsive to movement of said steer 20 means connecting the motor to the receiver for
ing device, a mechanical connection operatively
returning said valve to closed position upon
connecting the receiver unit to the valve to move
movement of the steered member.
the same to open position to thereby connect
STANLEY I. MACDUFF.
the motor to said source, whereupon the motor
REFERENCES CITED
moves said steeredv member, means in the closed 25
hydraulic system to compensate for pressure
The following references are of record in the
changes therein due to temperature variation
of the ?uid, and means connecting the motor
to the receiver for returning said valve to closed
?le of this patent:
position as the steered member is moved to 30 iNumber
thereby provide a follow up control.
2,252,660
2. A hydraulic actuated power steering ap
2,401,364
paratus for an aircraft having a steering device
2,418,325
and a steered member, said apparatus compris
2,424,233
ing a ?uid motor drivably connected to said 35
_
steered member, a source of ?uid under pressure
having a connection to said motor, a valve in
Number
the connection, said valve shittable from a
527,013
UNITED STATES PA'I‘ENTS
» Name
Date
Kuliko? ______ __._- Aug. 12, 1941
Mercier __________ __ June 4, 1946
Wassall et al _______ __ Apr. 1, 1947
Greenough ______ __ July 22, 1947
FOREIGN PATENTS
Country
‘
Date
Great Britain ______ _- Oct. 1, 1940