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Патент USA US3019781

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Feb. 6, 1962
Filed June 9, 1960
2 Sheets-Sheet 1
FIG. 2
Feb. 6, 1962
Filed June 9, 1960
2 Sheets-Sheet 2
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ited States
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3 ,0 l 9 ,7 7 l
Patented Feb. 6, 1962
the cylinders 13 and 14 for reasons that will become ap
William E. Heese, Old Saybrook, and Robert F. White,
Stonington, Conn, assignors to General Dynamics Cor
parent hereinafter,
Floating, pistons 35 and 36, slidably mounted in the
cylinders 29 and 30, carry sealing O-rings .37 and 38 in
grooves 30 and 40. Cylindrical recesses 41- and
poration, New York, N.Y., a corporation of Delaware 5 annular
42, having the same diameter as the cylinders 13 and 14,
Filed June 9, 1960, Ser, _No. 35,077
are cut out of the pistons v.85 and 36 to receive the inner
2 Claims. (Cl. 121—38)
ends of the racks15 and 16, thereby minimizing rockin
of the sliding members.
This invention relates to hydraulic actuators and, more
Three ?uid ports 43, 44 and 45 in the housing 10,
particularly, to an actuator having an output shaft‘ selec 10
adapted to be connected to fluid' supply and return ducts,
tively rotatable to three positively indexed angular posi
are joined *by ?uid passages to the cylinders 13, 14, 29
and 30. In particular, the port 43 is placed in ?uid com
Hydraulic rotary actuators, which have been adopted
munication with the outer ends of the larger diameter
for use with many mechanical devices, combine rugged
ness and reliability with high torque output when supplied 15 cylinders 29 and 30 by passages 46, 47 and 48 in the hous
ing 10; the port 44 is placed in ?uid communication with
with suitable hydraulic ?uid pressures. Ordinarily rotary
actuators positively index their output shafts at two an
, the outer ends of the smaller diameter cylinders 13 and
gular positions. Attempts to provide three position ‘rotary
14 by ?uid passages 49 and 50; and the port 45 is placed
in ?uid communication with (l) the other ends of the
unduly complicated and uneconomic devices of relatively 20 cylinders '14 and 30 at their junction by ?uid passage 51
and (2) with the other ends of the cylinders 13 and 29
great bulk.
at their junction by openings 52 and 53 in the inner ends
The present invention provides a simple compact hy
of the racks 16 and 15, respectively, and the chamber 27a.
draulic actuator rotating an output shaft to three posi
tively indexed angular positions with constant torque.
If desired, the ?uid passages may be formed by tubing
To this end, a preferred embodiment of the invention in 25 external to the housing 10.
The operation of the hydraulic rotary actuator will be
cludes a housing formed with two parallel ?rst- cylinders
actuators have met with little success, such units being
slidably receiving piston-like racks operatively engaging
readily understood by referring to the schem-aticdiagrams
a pinion driven output shaft.
of FIGURES 3, 4 and 5 which illustrate schematically
the three positions to which the output shaft 28 is indexed
Two larger cylinders in the
housing, slidably mounting ?oating pistons, extend from
the ?rst cylinders. Three ports communicating with the 30 positively by hydraulic ?uid pressure. In the particular
ends of the cylinders and their junctions are adapted to
embodiment of the invention described, the shaft 28 is
rotated with constant torque to positions at 0°, 90° or
be connected to ?uid supply and return ducts for rotating
180°, depending on the supply and return ?uid pressures
applied to the ports 43, 44 and 45. It will be understood
These and further advantages of the invention will be 35 that such positions are illustrative only and that the out
put shaft 28 could be rotated to any three ‘angular posi
more readily understood when the following description is
tions by varying the length of the racks 15 and 16 to add
read in connection with the accompanying drawings, in
or subtract a desired number of the teeth 25 and 26 en
gaging and rotating the pinion 27. Furthermore, the
FIGURE 1 is an elevation of a three position hydraulic
rotary actuator constructed in accordance with the prin 40 shaft 28 may be rotated through an angle greater than
the output shaft to a selected one of the three angular
ciples of the present invention;
FIGURE 2 is a longitudinal section of the actuator of
360° between adjacent positions, if desired.
Referring to FIGURE 3, which shows the output shaft
28 at 0° position, ?uid supply pressure, designated S, is
FIGURE 1 taken {along the view line 2—2 looking in the
applied to port 44 and a ?uid return, designated R, is pro
direction of the arrows; and
FIGURES 3, 4 and 5 illustrate the hydraulic actuator 45 vided at ports 43 and 45. With this arrangement, the
racks 15 and 16 are urged to positions most remote from
schematically in its three positively indexed angular posi
the plugs 21 and 22, carrying with them the ?oating pis
tons 35 and 36, and rotating the shaft 28 to 0°.
Referring to a typical embodiment of the invention in
When it becomes desirable to operate the shaft 28 to
greater detail with reference to the drawings, the hy
draulic rotary actuator shown in FIGURES 1 and 2 in 50 its 90° position as shown in FIGURE 4, ?uid supply pres
sure is applied to the ports 43 and 44 while a ?uid return _
cludes a housing 10 formed with suitable mounting ?anges
is provided at the port 45. Such a combination of ?uid
11 and 12. The housing 10 may be bolted to a valve
pressures urges the rack 15 and the ?oating piston 35 in
housing, for example, to control a three position valve.
A pair of parallel ?rst cylinders 13 and 14 provided in
opposition directions toward each other, and the same is
the housing 10 slidably receive piston-like racks 15 and 16 55 also true of the rack 16 and the piston 36. However,
since the larger diameter of the ?oating piston cylinders
carrying O-rings 17 and 18 in annular grooves 19 and 20,
provides areas upon which the supply pressure acts that
adjacent to their outer ends, for sealably engaging the
are greater than the areas subjected to supply pressure
cylinder walls. Threaded plugs 21 and 22 provided with
in connection with the racks, the pistons 35 and 36 are
suitable seals 23 and 24 respectively close the ends of
60 displaced to the inner ends of the cylinders 29 and 30,
the cylinders 13 and 14.
as show in FIGURE 4, and the ends of the racks 15 and
The racks 15 and 16 carry teeth 25 and 26 that opera
16 are displaced into the recesses 41 and 42. Accord
tively engage opposite sides of a pinion 27 mounted in a
ingly, the output shaft 28 will be rotated to its 90° posi
chamber 27a in the housing 10. An output shaft 28,
either secured to or integral with the pinion 27, is suitably
journaled in the housing 10 and extends therefrom in one 65, Finally, to rotate the output shaft 28 to its 180° posi
tion, as shown in FIGURE 5 (and also in FIGURE 2),
direction (as shown) or in both directions, if desired.
?uid supply pressure is applied to the ports 43 and 45
A pair of second cylinders 29 and 30 in the housing 10,
and a ?uid return provided for the port 44. The pressure
their ends closed by threaded plugs 31 and 32 carrying
appropriate seals 33 and 34, extend from the open ends 70 at the port 43 provides a greater total force on the outside of the ?oating pistons 35 and 36 than is applied to
of the cylinders 13 and 14 along their axes. The cylin
the inside surfaces thereof by the ?uid pressure at the
ders 29 and 30 have a somewhat greater diameter than
port 45 due to the smaller diameter of the cylinders 13
and 15. However, the ?uid pressure at the port 45 dis!
cation between the ?rst port and one end of each of the
?rst cylinders, two second cylinders formed in the hous
ing and extending from the other ends of the ?rst cylin
ders along their axes, the diameter of the second cylinders
being greater than that of the ?rst cylinders, two pistons
respectively slidably mounted in the second cylinders, sec
places the racks 15 and 16 ‘outwardly with precisely the
same force that urges the racks inwardly since the ?uid
pressure acts effectively against the same diameter cylinder
in both instances.
It will be apparent that the inventive hydraulic actua
ond ?uid passage means providing'?uid communication
tor provides a compact unit supplying constant torque
between the second port and the end of each of the sec
rotation of an output shaft to any ‘three selected angular
ond cylinders remote from the ?rst cylinder, and third
positions. The above described embodiment of the in 10 ?uid passage means providing ?uid communication be
tween the third port and the junctions of the ?rst and
vention is, of course, illustrative only and modi?cations
second cylinders.
thereof will occur to those skilled in the art. Therefore,
2. Apparatus as de?ned in claim 1, wherein a cylin
rical recess is formed in each of the pistons having the
the invention is not to be limited to the speci?c apparatus
disclosed herein but is to be de?ned by the appended
We claim:
15 same diameter ‘as the ?rst cylinder to receive one end of
each of the piston-like racks.
1. A three position rotary hydraulic actuator compris
ing a housing, an output shaft journaled in the housing, a
pinion in the housing on the shaft, ?rst, second and thirdv
?uid ports in the housing adapted to be subjected to
?uid pressure to control the angular position of the shaft,
two ?rst parallel cylinders formed in the housing, two
parallel piston-like racks engaging opposite sides of the
pinion and respectively slidably mounted in the ?rst cylin
ders, ?rst ?uid passage means providing ?uid communi 25
References Cited in the ?le of this patent
Crocker _______________ __ Apr. 5, 1927
Campbell _____________ __ May 26, 1931
Lenz _________________ __ Oct. 12, 1937
Vogel ________________ __ July 26, 1960
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