U.S. patent number 3,783,746 [Application Number 05/250,663] was granted by the patent office on 1974-01-08 for rotary actuator.
This patent grant is currently assigned to Greer Hydraulics, Inc.. Invention is credited to Alphonse A. Jacobellis.
United States Patent |
3,783,746 |
Jacobellis |
January 8, 1974 |
ROTARY ACTUATOR
Abstract
The invention relates to a rotary actuator of the type having a
movable vane positioned in an arcuate chamber and secured to and
extending radially outward from a shaft extending coaxially with
the axis of said arcuate chamber. The arcuate chamber forms a
central part of a substantially U-shaped chamber having a pair of
legs open at their outer end, each chamber receiving a deformable
bladder having a closed end adapted to react against opposed ends
of the vane, means being provided to permit fluid under pressure to
charge said bladders to effect expansion of one of the bladders for
consequent movement of said movable vane and the shaft to which it
is secured with resultant compression of the other bladder.
Inventors: |
Jacobellis; Alphonse A.
(Woodland Hills, CA) |
Assignee: |
Greer Hydraulics, Inc. (Los
Angeles, CA)
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Family
ID: |
26818610 |
Appl.
No.: |
05/250,663 |
Filed: |
May 5, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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120656 |
May 3, 1971 |
3680982 |
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Current U.S.
Class: |
92/121;
92/92 |
Current CPC
Class: |
F15B
15/08 (20130101) |
Current International
Class: |
F15B
15/00 (20060101); F15B 15/08 (20060101); F01c
009/00 () |
Field of
Search: |
;92/121,92 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schwadron; Martin P.
Assistant Examiner: Hershkovitz; Abe
Attorney, Agent or Firm: Colvin; Arthur B.
Parent Case Text
This application is a continuation-in-part of copending application
Ser. No. 120,656, filed May 3, 1971, now U.S. Pat. No. 3,680,982.
Claims
Having thus described my invention, what I claim as new and desire
to secure by Letters Patent of the United States is:
1. A rotary actuator comprising a casing having a substantially
U-shaped cavity therein, the mid-portion of said U-shaped cavity
being substantially arcuate, said U-shaped cavity having a pair of
legs positioned respectively on each side of said arcuate portion
of said U-shaped cavity and in substantially the same plane, each
of said legs being open at its outer end, and defining chambers
substantially circular in cross section, a shaft extending through
said casing coaxial with the axis of said arcuate portion, a vane
movably mounted in said arcuate portion defining a chamber on each
side of said vane, said chambers forming part of the chambers
defined by said legs, said vane being operatively connected to said
shaft and extending radially therefrom, a pair of bladders
positioned respectively in said chambers, each of said bladders
having an end portion with a closed end associated respectively
with opposed surfaces of said vane, each of said bladders being
conformed to effect movement of each of said end portions thereof
in an arcuate path in said arcuate portion of said U-shaped cavity,
for reaction of the closed end of the bladders against the opposed
surfaces of said vane, means to close the open end of each of said
chambers defined by said legs and to secure the end of said bladder
adjacent thereto in fixed position and means selectively to charge
each of said bladders, thereby to effect rotation of said shaft
when the associated bladder is charged with fluid under
pressure.
2. A rotary actuator comprising a casing having a substantially
arcuate cavity therein, a shaft extending through said casing
coaxial with the axis of said arcuate cavity, a vane in the form of
a segment of a toroid, having the ends of the segment defining
reaction seats, said vane being movably mounted in said cavity
defining a chamber on each side of said vane, said vane being
operatively connected to said shaft and extending radially
therefrom, a pair of bladders positioned respectively in said
chambers, each of said bladders having an end portion with a closed
end associated respectively with the reaction seats defined by the
opposed end surfaces of said vane, each of said bladders being
conformed to effect movement of each of said end portions thereof
in an arcuate path in said arcuate cavity, for abutment of the
closed end of the bladders against said reaction seats defined by
the opposed surfaces of said vane to effect rotation of said shaft
when the associated bladder is charged with fluid under
pressure.
3. The combination set forth in claim 2 in which the reaction seat
defined by each of the ends of said segment is in the form of a
cup-shaped recess.
4. The combination set forth in claim 2 in which the segment of a
toroid defining said vane is substantially circular in cross
section, said arcuate cavity is substantially circular in cross
section, the end surfaces of said vane extend substantially
radially with respect to the axis of said toroid.
5. A rotary actuator comprising a casing having a substantially
arcuate cavity therein, a shaft extending through said casing
coaxial with the axis of said arcuate cavity, a vane movably
mounted in said cavity defining a chamber on each side of said
vane, said vane being operatively connected to said shaft and
extending radially therefrom, said casing having a pair of parallel
chambers therein, each substantially circular in cross section
having an open outer end and an open inner end, said inner ends
being in communication respectively with the ends of the chambers
defined by said vane in said arcuate cavity, whereby said parallel
chambers and the chambers in said arcuate cavity define a
substantially U-shaped chamber extending in a plane perpendicular
to the axis of said shaft, a pair of bladders positioned
respectively in said chambers, each of said bladders having a body
portion positioned respectively in one of said pair of parallel
chambers, each of said bladders having an end portion with a closed
end extending respectively into the ends of said arcuate cavity and
associated respectively with opposed surfaces of said vane, each of
said bladders being conformed to effect movement of each of said
end portions thereof in an arcuate path in said arcuate cavity, for
reaction of the closed end of the bladders against the opposed
surfaces of said vane, means retaining the end of each of the
bladders remote from the closed end thereof in fixed position in
each of said pair of chambers and means selectively to charge each
of said bladders with fluid under pressure, to effect rotation of
said shaft when the associated bladder is charged.
6. The combination set forth in claim 5 in which means are provided
to close the open outer ends of each of said chambers.
7. The combination set forth in claim 5 in which each of said
bladders has a mouth remote from the closed end thereof, each mouth
having a radially extending annular flange, and means closing the
open outer end of each of said chambers and clamping the flange of
each of said bladders in a fixed position.
8. The combination set forth in claim 5 in which each of said
bladders has a mouth remote from the closed end thereof, each mouth
having a radially extending annular flange, a cap associated with
each of the open outer ends of each chamber, means to secure said
caps in fixed position and to clamp the flange of an associated
bladder against said outer end, each of said caps having a port to
which a source of fluid under pressure may be connected.
9. The combination set forth in claim 8 in which one of said ports
has a fitting to which a source of liquid under pressure may be
connected and the other of said ports has a fitting to which a
source of gas under pressure may be connected.
10. The combination set forth in claim 5 in which the body portion
of each of said bladders is substantially cylindrical and is
positioned respectively in each of said pair of parallel chambers
substantially coaxial with the longitudinal axis thereof, each of
the end portions of said bladders being bent inwardly with respect
to the longitudinal axis of the body portion in a plane parallel to
the plane of said U-shaped chamber, with the axis of each end
portion being substantially aligned with the axis of the arcuate
cavity, the wall thickness of at least the major portion of the
body portion being substantially uniform and the wall thickness of
the end portion being greater at its inner side than its outer
side, whereby when said bladders are charged with fluid under
pressure, the body portion will elongate in direction substantially
parallel to the longitudinal axis of the body portion and the end
portion will elongate in an arcuate path, the outer side of the end
portion stretching at a faster rate than the inner side.
11. A rotary actuator comprising a casing having a substantially
arcuate cavity therein, a shaft extending through said casing
coaxial with the axis of said arcuate cavity, said cavity having a
bore through which said shaft extends, an arcuate seat is provided
in said casing coaxial with the axis of said shaft, said shaft has
a coaxial hub rigid therewith, the ends of said shaft extending in
opposed directions from said hub, the latter resting on said seat,
a vane in the form of a segment of a toroid having its axis coaxial
with said shaft, said vane being movably mounted in said cavity
defining a chamber on each side of said vane, said vane being
operatively connected to said shaft and extending radially
therefrom, a pair of bladders positioned respectively in said
chambers, each of said bladders having an end portion with a closed
end associated respectively with opposed surfaces of said vane,
each of said bladders being conformed to effect movement of each of
said end portions thereof in an arcuate path in said arcuate
cavity, for reaction of the closed end of the bladders against the
opposed surfaces of said vane to effect rotation of said shaft when
the associated bladder is charged with fluid under pressure.
12. The combination set forth in claim 11 in which the inner
periphery of said vane has an arcuate surface of curvature
complementary to that of the peripheral surface of the hub, said
two surfaces being juxtaposed and means securely to retain said
vane in fixed position with respect to said hub.
13. The combination set forth in claim 11 in which the hub and the
arcuate surface of the vane each has an aligned radial bore and a
pin secured by force fit in said bores securely retains the vane in
fixed position with respect to said hub.
14. A rotary actuator comprising a casing comprising two
substantially identical sections defining a front and rear section,
each of said sections having a pair of parallel cavities and an
arcuate cross member each substantially semicircular in cross
section, said pair of parallel cavities and the associated arcuate
cavity defining a substantially U-shaped cavity, each of said
sections having an outwardly extending perimeter flange and an
abutment section between the pair of parallel cavities, said
sections when juxtaposed defining a substantially U-shaped chamber
substantially circular in cross section, with an arcuate cavity
being defined by the juxtaposed cross members, a gasket interposed
between the juxtaposed perimeter flanges, and an additional gasket
interposed between said abutment sections, means clamping said
sections together, the lower ends of said abutment sections being
arcuate and defining a seat, a bore coaxial with the arcuate cavity
defined by said arcuate cross members extending through said front
and rear sections and aligned with said seat, a shaft extending
through said bores coaxial with the axis of said arcuate cavity and
having a portion resting on said seat, a vane movably mounted in
said arcuate cavity defining a chamber on each side of said vane,
said vane being operatively connected to said shaft and extending
radially therefrom, a pair of bladders positioned respectively in
said chambers, each of said bladders having an end portion with a
closed end associated respectively with opposed surfaces of said
vane, each of said bladders being conformed to effect movement of
each of said end portions thereof in an arcuate path in said
arcuate cavity, for reaction of the closed end of the bladders
against the opposed surfaces of said vane to effect rotation of
said shaft when the associated bladder is charged with fluid under
pressure.
15. The combination set forth in claim 14 in which each of the
inner surfaces of said bore extending through said front and rear
sections has an annular recess coaxial with said bore, said shaft
has an enlarged diameter hub between its ends resting on said
arcuate seat, a pair of thrust washers encompass said shaft and
straddle said hub, said washers being seated respectively in said
annular recesses.
16. The combination set forth in claim 14 in which complementary
pins and recesses are provided in said perimeter flanges to align
said front and rear sections when they are juxtaposed.
17. The combination set forth in claim 14 in which said abutment
sections each has a recess therein and the additional gasket is
positioned in said recess.
18. The combination set forth in claim 14 in which one end of said
shaft protrudes beyond the outer surface of an associated plate, a
hub is secured to said protruding end of said shaft, said hub
having a radially extending stop finger and abutment means
positioned on the other surface of said plate to limit the arcuate
movement of said stop finger and said shaft.
19. A rotary actuator comprising a casing having a substantially
U-shaped cavity therein, said U-shaped cavity having a pair of legs
and an arcuate cross member connecting one end of each of said
legs, each of said legs being open at its other end, said arcuate
cavity being substantially circular in cross section and said legs
defining cylindrical chambers substantially circular in cross
section, a shaft extending through said casing coaxial with the
axis of said arcuate cross member, a vane movably mounted in the
chamber defined by said arcuate cross member, said vane being
operatively connected to said shaft and extending radially
therefrom, a pair of bladders positioned respectively in the
cylindrical chambers defined by each of said legs, each of said
bladders having an end portion with a closed end associated
respectively with opposed surfaces of said vane for reaction of the
closed ends of the bladders against the opposed surfaces of said
vane to effect rotation of said shaft when the associated bladder
is charged with fluid under pressure.
20. The combination set forth in claim 19 in which each of said
bladders has a mouth remote from the closed end thereof, each mouth
having a radially extending annular flange, a cap associated with
each of the open outer ends of each of the chambers defined by said
legs, means to secure said caps in fixed position and to clamp the
flange of an associated bladder against said outer end, each of
said caps having a port to which a source of fluid under pressure
may be connected.
Description
As conducive to an understanding of the invention, it is noted that
where an actuator utilizes a movable vane positioned in a casing
and which is connected to and extends radially from a rotary shaft
and which is subjected to the force imparted by the introduction of
fluid such as liquid under pressure into a cavity defined on one
side of the movable vane to effect rotary movement of the vane and
the shaft, by causing the fluid in a cavity defined on the other
side of the vane to be expelled from said cavity, leakage of fluid
between the free end of the vane and the adjacent surface of the
cylinder in which the vane is rotating, results in a high degree of
inefficiency of the unit.
Where, to prevent leakage, close tolerances are established between
the free edges of the vane and the associated surfaces of the
casing in which it is rotating, the cost of machining the edges of
the vane and the surface of the casing is extremely high and at
best leakage still occurs due to the requirement that sufficient
clearance be provided to permit free rotation of the vane.
Where, to prevent such leakage, bladders are provided on each side
of the vane so that upon expansion of one of the bladders force
will be exerted against the vane to move the latter, if the
majority of the force exerted by the expanding bladder is not
against the vane but is applied to the side wall of the casing in
which the bladder is positioned, inefficiency of operation will
result.
Where bladders are used and in the event of failure it is necessary
to completely disassemble the unit for replacement, the resultant
"down time" may have serious consequences.
It is accordingly among the objects of the invention to provide a
bladder operated rotary actuator which is relatively simple to
fabricate at relatively low cost and which will positively avoid
leakage from one side of the movable vane to the other without need
for machining or close tolerances being maintained and which may
readily be disassembled for replacement of the bladders in a
minimum period of time.
According to the invention these objects are accomplished by the
arrangement and combination of elements hereinafter described and
more particularly recited in the claims.
In the accompanying drawings in which are shown one or more of
various possible embodiments of the several features of the
invention.
FIG. 1 is a perspective view of the actuator.
FIG. 2 is a bottom plan view thereof taken along line 2--2 of FIG.
1.
FIG. 3 is a rear view taken along line 3--3 of FIG. 1.
FIG. 4 is a sectional view on an enlarged scale taken along line
4--4 of FIG. 3.
FIG. 5 is a sectional view taken along line 5--5 of FIG. 4.
FIG. 5A is a sectional view with parts broken away similar to FIG.
5 of another embodiment of the invention.
FIG. 6 is a sectional view taken along line 6--6 of FIG. 5.
FIG. 7 is a fragmentary detail view on an enlarged scale taken
along line 7--7 of FIG. 5.
FIG. 8 is a fragmentary detail view on an enlarged scale taken
along line 8--8 of FIG. 6.
FIG. 9 is a perspective view of one of the bladders used in the
actuator.
FIG. 10 is a longitudinal sectional view on a slightly smaller
scale taken along line 10--10 of FIG. 9.
FIG. 11 is a transverse sectional view taken along line 11--11 of
FIG. 10.
FIG. 12 is a fragmentary detail view on an enlarged scale taken
along line 12--12 of FIG. 4.
FIG. 13 is a perspective view of the front section of the actuator,
and
FIG. 14 is a perspective view of the movable vane of the
actuator.
Referring now to the drawings, the actuator 10 comprises a housing
formed from a front section 11 and a rear section 12.
As is clearly shown, the sections 11 and 12 are similar in
configuration and for simplicity, front section 11 will be
described in detail with corresponding elements of rear section 12
having the same reference numerals primed.
Thus, front section 11, referring to FIG. 13, has a substantially
U-shaped concavity 13, the parallel legs 14 of which are
semi-circular in cross section and are joined by a cross member 15
which is arcuate both in cross section and in plan view.
The section 11 has an outstanding flange 16 through which a series
of spaced openings 17 extend. Thus, when the flanges 16, 16' of
sections 11 and 12 are placed into juxtaposition with a gasket 18
intervening, and bolts 19 are passed through the aligned openings
17, 17' in flanges 16, 16' and through associated openings in
gasket 18, and nuts 21 are screwed on the ends of the bolts 19 and
tightened, the sections 11 and 12 will be securely retained
together as shown in FIG. 4 for example with the juxtaposed
semi-circular concavities 13, 13' of sections 11, 12 defining a
U-shaped housing that has two parallel chambers C-1, C-2 defined by
the associated pairs of juxtaposed legs 14, 14' joined by arcuate
cross members 15, 15' all of which are substantially circular in
cross section.
In order to align the front and rear sections 11 and 12, as shown
in FIGS. 5 and 7, the flange 16 of section 11 has a plurality of
outstanding pins 20 rigid therewith which extend through aligned
openings 20' in gasket 18 into associated sockets 20" in section
12.
As shown in FIGS. 4, 6 and 13, each section 11 and 12 has a bore 23
therethrough, said bores being longitudinally aligned when the
sections are secured together as above described.
The inner surfaces 22 of the upper central portion 24 (FIGS. 5, 6
and 13) of each of the sections 11, 12 are in juxtaposition with a
gasket 25 therebetween, the latter being positioned in a recess 25'
in such inner surface 22, said upper portions 24 being securely
retained together clamping the gasket 25 therebetween, by bolts 26
with nuts 27 screwed thereon.
The lower end 30 of each of the upper central portions 24 is
arcuate as shown in FIGS. 6 and 13 and when such central portions
24 are juxtaposed, said lower ends 30 define an arcuate seat 32 for
a hub 31.
As shown in FIGS. 4 and 6, a shaft 35 extends through the aligned
bores 23 and through a hub 31, the latter being secured to the
shaft as by pinning or being formed integrally with said shaft.
A pair of thrust washers 36 encompass shaft 35, straddling hub 31
as shown in FIG. 4, the washers being seated in annular recesses 37
coaxial with bores 23 (FIG. 6).
The shaft 35 has a pair of annular grooves 38 positioned
respectively on each side of hub 31 (FIG. 4) each groove 38
mounting an O-ring 39 to provide a rotary seal.
The ends of shaft 35 which protrude beyond sections 11, 12 are
rectangular in cross section as at 41, 42. As shown in FIG. 1, the
front section 11 has a central boss 43 formed integrally therewith,
having four radiating legs, two of which , designated by the
numeral 46, defining stop legs.
Referring to FIGS. 1, 4 and 6, the end 41 of shaft 35 extends
through the rectangular bore 47 of the hub 48 of a stroke indicator
and detent 49 the hub 48 being secured to end 41 by set screw 51.
Rotation of shaft 35, in the manner hereinafter described, is
limited by the abutment of the finger 52 of detent 49 against
adjustable set screws 53 screwed through the stop legs 46.
The rear section 12 as shown in FIGS. 3, 4 and 6 also has a central
boss 54 formed integrally therewith, the latter having a central
arcuate hub 55 through which the end 42 of shaft 35 extends and
four radiating mounting legs 56 each with a threaded opening 57 to
faciliate mounting of the actuator 10 to the casing of a valve (not
shown), for example, which is to be operated by the actuator.
In order to lubricate the hub 31, with respect to its seat 32, as
shown in FIGS. 5, 6, 8 and 13 for example, the inner surface 22 of
each of the upper central portions 24 of sections 11 and 12 has a
vertical groove 59, the lower end 61 of each of which is in
communication with the arcuate seat 32 for hub 31.
The upper end 62 of each groove 59 is inclined and meet at 62' so
that both grooves 59 are in communication with a transverse
threaded filling bore 63 extending through section 11, said bore 63
having a removable plug 64 screwed therein.
Rigid with hub 31 and extending radially therefrom is a torque arm
71 which as illustratively shown in FIG. 6 is cylindrical in cross
section and has one end positioned as by force fit into a radial
bore 72 in the hub 31.
The torque arm mounts a follower member or vane 73 which, as shown
in FIGS. 6 and 14, is a segment of a toroid and is substantially
cylindrical in cross section conforming to the cross section of the
arcuate cavity 33 (FIG. 6) defined by the juxtaposed cross members
15, 15' of the U-shaped concavities 14, 14'.
Thus, the vane 73 is of diameter just slightly smaller than that of
the arcuate cavity 33 as shown in FIG. 6 so that although the vane
will move freely in said cavity 33 there will be a minimum
clearance between the vane and the wall of cavity 33.
The vane 73 when viewed in vertical cross section with respect to
shaft 35, as shown in FIG. 5, has an arcuate inner end 74 of
curvature complementary to that of hub 31 so that said inner end 74
may fit snugly against the hub.
The outer end 75 of the vane 73 (FIG. 5) is also arcuate, of
curvature complementary to that of the inner surface of arcuate
cavity 33 and occupies an arc of approximately 85.degree..
More particularly the ends 76, 77 of the toroidal segment defining
the vane are cup-shaped and define reaction seats as will
hereinafter be described.
Although the vane 73 could be of any suitable rigid material, in
the illustrative embodiment shown it is molybdenum disulfide filled
nylon and has a bore 78 extending radially with respect to the axis
of the toroid and of diameter substantially the same as that of
torque arm 71 which is force fitted into bore 78.
Positioned in each of the chambers C-1, C-2 defined by the
juxtaposed sections 11, 12 on each side of the vane 73 is a bladder
83, 84 of resilient deformable material such as rubber or other
material having like characteristics.
Since the bladders 83, 84 are identical, only bladder 83 will be
described.
Referring to FIGS. 9 and 10, the bladder 83 has a cylindrical body
portion 85, having an open mouth 86 with an annular flange 87
extending radially outward therefrom. The lower end portion 88 of
the bladder has a rounded closed end 89 and such lower end portion
88 is bent or curved to extend arcuately with respect to the
longitudinal axis of the body portion 85. More particularly, the
axis of such end portion 88 extends at substantially an obtuse
angle with respect to the longitudinal axis of said body
portion.
As is clearly shown in FIGS. 5, 10 and 11, the wall of the
cylindrical body portion 85 of the bladder is of substantially
uniform thickness around its entire circumference from
substantially the mouth of the bladder to the arcuate portion 88 is
designated by the letter A.
The inner or concave side 91 of the wall of the bladder defined by
the concavity of the lower portion 88 of the bladder is of
progressively increasing thickness from the upper end 92 of such
inner side to substantially the central portion 93 of the closed
end of the bladder and then is of progressively reduced thickness
until it merges with the wall of the body portion 85 as at 94.
In addition, referring to FIG. 11, the thickness of the wall of the
arcuate portion 88 when viewed in cross section is maximum at the
mid portion 95 of the concave side 91 and substantially
progressively decreases along each side of said mid portion 95 of
the concave side 91 from such mid portion 95 to the mid portion 96
of the opposed outer convex side 97.
As a result of the foregoing construction of the bladder it is
apparent that the wall of the closed end 89 is relatively thick so
that it will withstand abrasion. Furthermore, since the wall
thickness of the outer convex side 97 of the end portion 88 is less
than that of the inner concave side 91, when the bladder expands,
the thinner wall of the outer side 97 will stretch at a faster rate
than the thicker wall of the inner side 91 so that the closed end
89 of the lower portion 88 of the bladder will tend to move in an
arcuate path against the seats defined by the cup-shaped ends 76,
77 of vane 73.
The bladders 83, 84 are mounted in the chambers C-1, C-2 as shown
in FIG. 5 so that the arcuate lower end portions 88 of the bladder
will be aligned with the portions of the arcuate cavity 33 on each
side of vane 73.
To this end, as shown in FIG. 12, the top surface 98 of each of the
parallel legs of the U-shaped housing defined by the juxtaposed
substantially semi-circular concavities 13, 13' has an annular
recess 101 positioned inwardly of the outer periphery thereof
defining an annular shoulder 102. A second annular recess 103 is
provided in said top surface, positined inwardly of shoulder 102
and of greater depth than recess 101 and defining an annular
shoulder 104 which has an annular groove 105 therein, the inner
edge 106 of which is beveled outwardly as shown. The mouth 107 of
each chamber C-1, C-2 defined by the juxtaposed concavities 13, 13'
is rounded as shown.
The flange 87 of each bladder has a thickened outer periphery, the
lower surface of which is triangular in cross section as at 108 as
shown in FIG. 10, with the apex of the triangle directed
downwardly. The upper surface of the thickened outer periphery is
also triangular in cross section as at 109 with the apex of the
triangle directed upwardly.
A bladder 83, 84 is positioned in each of the chambers C-1, C-2 as
shown in FIG. 5 with the inner or concave side 91 of each of the
bladders positioned adjacent the inner side of each chamber so that
the arcuate bottom or end portion 88 of each bladder will be
aligned with the arcuate cavity 33 of the U-shaped chamber. The
flange 87 is positioned so that the triangular lower surface 108
thereof is positioned in annular groove 105 as shown in FIG.
12.
Means are provided to clamp the flanges 87 of each of the bladders
against the top surface 98 of each chamber. Thus, a pair of
identical cap plates 111, 112 are provided. Referring to FIG. 1 for
example, each cap plate has a base 113 which is substantially
square in plan and has four bosses 114 rising from each corner
thereof, each having a bore 115 therethrough. In addition, the base
113 has a central hub 116 which has a threaded bore 117
therethough.
The square base 113 is of dimension corresponding to the dimension
of a flange 121 extending outwardly from the mouth 107 of each
chamber C-1, C-2, the top surface of said flanges 121 defining the
top surface 98 above referred to. More particularly the rectangular
flange 121 is formed by the juxtaposition of the two half flanges
121a shown in FIG. 13.
The underface of each base 113 (FIG. 12) has a cylindrical hub 124
depending therefrom defining an annular shoulder 125 which seats on
top surface 98 when the cylindrical hub 124 is positioned in
annular recess 101 with the periphery of the hub 124 seated on
shoulder 102. The undersurface of hub 124 adjacent the periphery
thereof has an annular groove 126 in the form of an inverted
triangle, to accommodate the upper triangular portion 109 of flange
87.
The thickness of the periphery of the flange 87 is greater than the
distance between the aligned recess 105 and groove 126, so that
when the cap 112 for example, is in seated position as shown in
FIG. 12, the periphery of the flange 87 will be compressed to fill
the region between annular recess 105 and groove 126, the body
portion 85 of each bladder being spaced inwardly from the wall W of
each chamber C-1, C-2.
To clamp the caps 111, 112 against flanges 121, a screw 131 is
passed through each of the openings 115 in bosses 114, into an
associated aligned threaded opening 132 in flange 121 as shown in
FIG. 12.
The actuator above described may be utilized to operate a three way
valve for example, which has a neutral position and two operating
positions on each side of the neutral position.
The actuator may be secured to the casing of the valve by securing
the hub 54 to a mounting plate on the valve by means of screws (not
shown) extending into the threaded openings 57. When so mounted,
the end 42 of shaft 35 would be coupled to the shaft of the
valve.
When the vane 73 is in the position shown in FIG. 5, the valve will
be in its neutral position. Assuming that both of the bladders 83,
84 are fully charged with a fluid such as oil through the ports 117
of caps 111, 112 so that the bladders are expanded and stretched
and completely fill the associated chambers C-1, C-2.
Under such fully charged condition of the bladders the closed ends
89 thereof will have moved against the cup-shaped seats 76, 77 of
the vane 73 as shown in broken lines in FIG. 5.
The actuator is now ready for operation. Assuming that it is
desired to rotate the shaft 35 in a counter-clockwise direction
from the neutral position shown in FIG. 5, a source of oil under
pressure is applied to the port 117 of cap 112 and the port 117 of
cup 111 is connected to a reservoir.
As the fluid under pressure enters port 117, the fully charged
bladder 84 will stretch and expand. Since the bladder 84 is already
engaging the wall of the chamber C-2 and the cup-shaped seat 77,
the only portion of the force exerted by the expanding bladder that
will have any effect will be that exerted by the end 89 thereof
against seat 77 of vane 73. Consequently, such force will tend to
cause the vane 73 and shaft 35 to rotate in a counterclockwise
direction, the oil in bladder 83 being expelled from port 117 of
cap 111 to the reservoir. As a result, the three way valve (not
shown) controlled by shaft 35 will be moved from neutral position
to an operating position. To either close the three way valve or
move it to its other operating position, it is merely necessary to
connect the source of fluid under pressure to port 117 of cap 111
and to connect the port 117 of cap 112 to the reservoir and reverse
the operation previously described.
As above noted, since the thickness of the wall of cylindrical body
portion 85 of the bladders is uniform, such body portion 85 will
stretch or elongage and contract in a direction parallel to the
longitudinal axis of the body portion 85.
As the wall thickness of the outer or convex side 97 of the end
portion 88 of the bladder is less than that of the inner or concave
side 91 thereof, the expansion of the bladder at the end portion 88
thereof will cause such end portion 88 to move in an arcuate path,
i.e., the outer side 97 will stretch at a greater rate than the
inner side 91.
As a result, the closed end 89 of the bladder 84 will remain
substantially centered on its seat 77 so that a substantial force
will be exerted against the vane 73 to effect rotation of shaft 35
with consequent application of relatively great torque from shaft
35 to the valve being operated.
In the absence of the unique bladder above described, if the
expansion of the bladder along its length was solely in a direction
parallel to the longitudinal axis of the bladder, the majority of
force exerted by the closed end 89 of the bladder would be against
the wall of the chamber C-2 approximately at "X" (FIG. 5) rather
than against the vane 73, with resultant inefficiency of the
device.
Furthermore, due to such substantial force being exerted by the end
89 of the bladder both against the wall of the chamber as at "X"
and the adjacent edge "Y" of the vane, it would tend to restrain
movement of the vane 73 further reducing the efficiency of the
device.
By reason of the fact that the bladders 83, 84 form completely
sealed chambers, in which the fluid under pressure is received,
leakage of fluid past the movable vane 73 is completely eliminated
and there is no need for precision machining of the interior of the
housing or the portions of the vane 73 adjacent thereto.
In the event that after long use, the bladders must be replaced,
this is readily accomplished by merely removing the caps 111, 112
and the old bladders and positioning a new set of bladders in the
chambers C-1, C-2 and replacing the caps.
If for any reason it is necessary to completely disassemble the
actuator, this may readily be accomplished by merely removing the
end caps 111, 112 and then releasing the nuts 21 on bolts 19.
In the embodiment above described, the bladders 83, 84 are both
precharged with oil. However, it is within the scope of the
invention to use a fluid such as gas under pressure to effect
actuation of the vane, or as shown in the embodiment of FIG. 5A to
have one of the bladders, i.e., bladder 84, precharged with gas
under pressure through valve 135 which is then retained closed and
have oil under pressure forced into the port 117 of cap 111.
To ready the embodiment of the actuator shown in FIG. 5A for
operation, the bladder 84 is precharged with gas under pressure and
the bladder 83 with oil under pressure so that the vane 73 will be
set to the neutral position shown in FIG. 5.
To rotate the shaft 35 in a counterclockwise direction from the
position shown in FIG. 5, where the bladder 84 is charged with gas
under pressure, it is merely necessary to open a valve connecting
port 117 of cap 111 to reservoir. As a result, the bladder 83 will
expand and the end 89 thereof will move in an arcuate path reacting
against seat 77 of vane 73. To rotate the shaft 35 in a clockwise
direction from the position shown in FIG. 5, where the bladder 84
is charged with gas under pressure, it is merely necessary to
connect port 117 of cap 111 to a source of oil under pressure
greater than that in bladder 84. As a result, the end 89 of bladder
83 will move in an arcuate path reacting against seat 76 of vane 73
to rotate shaft 35 and the bladder 84 will be compressed by
movement of seat 77 of vane 73 against end 89 of bladder 84 and end
89 will retract in an arcuate path.
It is apparent that the gas filled bladder 84 will act as a spring
which will extend and retract depending upon conditions of
operation.
It is further apparent with the constructions above described that
by reason of the fact that the fluid used to react against the vane
is wholly contained in the bladders, no contamination of the
interior of the unit will occur so that corrosion of the side wall
of the casing will be eliminated and in addition impurities in the
oil used to charge the bladders will not clog the shaft of the
actuator.
* * * * *