US2973748A - Rotary actuators - Google Patents

Description

MalCh 7; 1961 G. H. LELAND ETAL v 2,973,748

ROTARY ACTUATORS Filed June 19, 1959 11E 5 GERALD H. aM/ and OL/VE/ F D4 W5, 0656/650 Units@ Se@ Preis ROTARY ACTUAToRs y Filed June 19, 1959, Ser. No. 821,447 4 claims. (Cl. 121-48) This inventionrelates to a rotary actuator and more particularly to a duid powered device for imparting stepwise rotary motion to an output shaft, however, the' invention is not necessarily so limited.

2. 22 and a cylindrical extension of the sleeve bearing 24. This bladder 34 is preferably molded so as to have a single open seam 36 in its outer periphery. This seam is sealed by compressing the adjacent marginal portions of the bladder between the end plate H14 and the adjacent end `of the housing member 12, the compressive force The present applicationk constitutes a continuation-inpart of the copencling application Serial No. 726,942, led April 7, 1958, by Gerald H. Leland and Oliver F. Davis for a Rotary Actuator. This copending application discloses a rotary actuator which is powered by fluid under y, pressure and which is characterized by a rotary output stroke which islarge in relation to the linearuid displacement in the actuator. vThe Adevice is also characterized by being small and compact in'view of the power transmitted. The present invention is the resultof eiforts to improve the means with which the propelling iluid is contained within the device.

An object of the present invention is to provide an improved iiuid receiving chamber construction for a fluid powered rotary actuator.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

In the drawing,

Figure l is a top plan View of the rotary actuator of this invention.

Figure 2 is a` sectional view taken substantially along the line 2-2of Figure 1.

Figure 3 is a sectional View taken substantially Ialong the line 3--3 of Figure 2. Y

Figure'4 is a sectional view like that of Figure 3 illus-` trating -a dilferent position for the rotary actuator.y

Figure 5 is a sectional View analogous to that of Figure 2 illustrating a modification. A

Referring to the drawing in greater detail, -a rotary actuator is illustrated in Figures l andZ. This rotary actuator comprises a generally cylindrical housing member 12 enclosed at one end by an end plate 14 'and lat the other end by a hub 16.` As best seen in Figurel, the end plate 1.4 is reenforced with radial ribs 15 so that it will have strength to contain a fluid under pressure. Bolts 18 secure the end plate 14 to one end of the housing member .12 and boltsZti secure the hub 1 6 to the opposite end of the housing member 12.A

A shaft 22 is journalled in the end plate 14 and in the hub 16 for. rotary movement about angaxis coincident with the geometric axis of the housing member' 12. For this purpose, sleeve bearings 24 and 26 are provided in thee'nd plate 14 and in the hub 1 6 respectively. The` shaft 22 has an intermediate spline portion 2S comprising parallel key ways which project outwardlyV beyond the periphery of the shaft.' Then shaft is secured against axialr movement by means'of washers 30 and. 312 engaging the opposite Tendsfof the spline portion. The washer 30 bears against `the sleeve bearing V24 while the washer 3,2 bears against an` inner surface of thehub 16. j

erally toroidal elastomeric bladder' 34 encircles the shaftV being supplied by the bolts 118. To facilitate assembly, the margins of the bladder at the seam 36 are beaded as illustrated and seated in complementary grooves in the end plate 14 and in the end of the housing member 12..

Provision for introduction of iluid into the bladder 34 is afforded by means of a passage 38 leading laterally into the end plate 14 and opening to the inner face thereof. -A tubular pin 40 penetrating the adjacent wall of the bladder 34 is press-fitted in the inner end of the passage 3'8. Within the bladder 34, this pin 40 has an annular outwardly projecting ange 42 compressingthe wall of the bladder 34 against the inner face of the end plate i4 to elfect a uid seal. The outer 4end ofthe passage 3S is provided with an internally threaded portion 44 for receipt of a suitable iittng.

Adjacent the bladder 34 is' an annular thrust plate 46 f journalled for sliding axial movement on the sleeve bearing 24. interposed between the thrust plate 46 and the bladder 34 are two annular shims or plates 48 and Si) Y encircling thesleeve bearing 24. The shim 48 has a central aperture larger than the diameter of thesleeveV bearing 24 so that play exists between this shim and the sleeve bearing. The same shim snugly tits the-inner Wall of the housing member 12'. The shim 50 has an outer diameter less than the inner diameter of the housing member 12 so that play exists between this shim and the housing member 12, however, this same shim has a central aperture snugly fitting the sleeve bea-ring 24. As a resultof this construction, the shims 48 and S0 collectively make a snug tit both with the inner wall of the housing member 12 and with the periphery of the sleeve bearing 24 while automatically compensating for any eccentricity between the housing member 12 `and the sleeve bearing 24. These two shims cooperate to prevent-extrusion of the'bladder 34 around the thrust plate 46 as Viiuid under pressure is introduced into the `bladder 34 to deliver thrust'y the plate 46, coacts with a parallel and adjacent annular plate.62 through the medium of ball elements 64, there being three ball elements 64 interposed between the plates 52 and 62 at 120 degree intervals.` As best seen in Figures 3 and 4, these ball elements 6,4 are caged or r trapped between opposing recesses 66 and 68 in the` plates` 52 and 62 respectively. The recesses 66 and 615 are inclined oppositely from the interface between the plates 52 and 62 and follow an arcuate path concentric with respect to the shaft 22. Referring to the position o-f the plates 52 and 62 illustrated in Figure 4, it will be observed that the application of an -axial thrust to the plate 52 will induce the ball" element between the plates 52 and 62 to roll toward the deep ends of the recesses 66 and 68. To accommodate such 'rolling movement,

`V`the Aplates, 52 and 62 are induced to rotate one relative to the other `about the axis of the shaft 22, such rotary motion bringing the plates 52 and 62 tothe relative position illustrated in Figure f3. It is thus apparent that an axial movement ofthe thrust plate 46 so as to compress ftheplates 52 :and 62 will be eifective to induce rotation `of the plate 52 relative to the plate 62.

Patented Mar. 7, i961.

groove 6i) in the The plate 52 is secured against rotation relative to the shaft 22 bymeans of a` hub portion 70 slidably engaging the spline portion 28 of the' shaft 22. The plate 62 is secured against rotation relative to the housing member 12 during the time that an axialv thrust is delivered thereto by means of av clutch disc 72 interposedv between the plate 62 and an adjacent shoulder 74 in the housing member 12. The arrangement is such that the plate 62 is rotatable in the housing member 12 when the bladder 34 is deflated, but is secured against rotation relative to the housing member 12 when fluid under pressure is introduced into the bladder 34.

Extending axially from the plate 62 is a cylindrical hub portion 76 which is engaged by a coil spring 78 anchored to the spline portion 2S of the shaft 22. This spring 78 biases the plate 62 relative to the plate 52 -to the position illustrated in Figure 4. Adjacent the spring 78 an annular detent wheel S slidably engages the spline portion 28 of the shaft 22. Notches in the periphery of the detent wheel 80 are engaged by a ball element 82 spring biased radially inwardly by a spring 84. Tension of the spring 84 is adjustable by means of a set screw 86 threadedly engaging the hub 16.

The notches in the periphery of the detent wheel 80 are spaced a distance corresponding -to the rotational movement induced by the recesses 66 and 68, which is substantially twice the arcuate length of each of the recesses. Hence, the central angle between adjacent notches in the detent wheel 80 is equal substantially to twice the central angle subtended by one of the recesses 66 or 68.

The operation is as follows: With the bladder 34 deilated and with the ball element 82 engaging one of the notches in the detent wheel 80, the spring 78 urges the plate 62 relative to the plate 52 so as to align the opposing recesses 66 and 68, as illustrated in Figure 4. Upon the introduction of uid under pressure into the bladder 34, an axial force is transmitted to the plate 62 which is restrained from rotation relative to the housing member 12 through pressured contact with the clutch disc 72. As the axial thrust increases, the plate 52 receives a rotational torque inducing it to rotate relative to the plate 62. This torque is transmitted to the spline portion 28 of the shaft 22 and, when this torque is great enough to force the ball element 82 out of its notch in the detent wheel 80, the plate 52 and shaft 22 rotate through an angle determined by the recesses 66 and 68. When the plate 52 has reached the extreme of its rotary movement relative to the plate 62, the ball element 82 engages a new notch in the detent wheel 80.k Upon subsequent reduction of the fluid pressure in the bladder 34, the plate 62 becomes free to rotate relative to the housing member 12 and the spring 78 restores the plate 62 to the relative position illustrated in Figure 4. This restoring movement causes the plates 52 and 62 to separate with the result that the bladder 34 is partially collapsed.

In View of this type of operation, it is apparent that repeated introduction of uid under pressure into the bladder 34 will produce a stepwise rotary movement of the output shaft 22 which may be used constructively in any desirable manner.

Figure 5 illustrates a modified uid powered rotary actuator 100 which embodies the present invention. This actuator is a dual unit constructed to actuate a shaft selectively in opposite directions. The housing for the dual actuator comprises generally two cylindrical housing members 102 and 104 secured to opposite sides of a central plate 106 by means of bolts 108. A toroidal bladder 112 is secured to each side of the plate 106 by compressing beaded marginal portions 110 of the bladders between the housing members and the surfaces of the plate 106. Provision for the introduction of fluid under pressure to the bladders 112 isaiforded byinlet conduits 114 located in the plane of the plate 106 and projecting laterally therein.

Two conduits 114 communicate with the bladder 112 to the left of the actuator, as viewed in Figure 5. One of these conduits serves as an inlet and the other serves as an outlet, suitable external valving, not shown, being employed to regulate the ow of fluid. Similar conduits communicating with the bladder to the right of the plate 106, as viewed in Figure 5, are located at degrees to those visible, hence are not visible in the illustration.

Communication from the conduits 114 to the interior of the bladders 112 is provided by tubular pins 116 presstted within the inner ends of the conduits 114 and penetrating to the interior of the bladders 112.. Inside the t' bladders the pins 116 are provided with outwardly projecting annular flanges 119 which compress the adjacent margins of the bladders against the plate 106.

A shaft 118 normal to the central plate 106 and passing centrally therethrough is journalled in the outer ends of the housing members 102 and 104. For this purpose, sleeve bearings 120 are provided in the ends of the housing members. These sleeve bearings may be a plastic, such as sintered nylon, or they may be any suitable metal having a low coeicient of friction in contact with the metal of the shaft 118. The central portion of the shaft 118 intermediate the ends of the housing members 102 and 104 is provided with outwardly projecting longitudinal key ways forming a spline 122.

A mechanism for converting axial movement induced by the bladders 112 to rotary movement of the shaft 118 substantially identical to that of the embodiment of Figures l and 2 is employed on each side of this dual actuator. For convenience, like parts of this mechanism are given like reference numerals with the letter' a added to differentiate the two embodiments. Thus, on each side of the dual actuator two opposing plates 52a and 62a separated by ball elements 64a are employed. The ball elements 64a are trapped in inclined arcuate recesses and are effective upon the application of axial pressure to the plate 52a to induce relative rotation between the plates. The plate 52a is secured to a hub 70a splined to the shaft 118. The plate 62a is biased by a spring 78a anchored to a `spline portion of the shaft 118. The plate 62a also coacts with an adjacent shoulder in the housing through the medium of a clutch lining 72a.

An axial thrust is transmitted from the toroidal bladder 112 to the conversion mechanism by means of an annular thrust plate 124 encircling the shaft 118 land separated from the adjacent plate 52a of the conversion mechanism by means of hall elements 126 which form a thrust bearing. As with theY embodiment of Figures 1 and 2, the bladders 112 are protected from extrusion around the thrust plates 124 by means of shims 48a and 50a interposed therebetween, the shims 48a snugly fitting the interior of the housing members and the shims 50a snugly fitting sleeve members 130 press-fitted in the plate 106 in surrounding relation to the splined portion of the shaft 118. In lieu of a caging member for the ball elements 126, flat spring members 128 are interposed between the shims 50a andthe thrust plates 124 on each side of the dual actuator. These springs preload the ball bearing 126 and also take up any play in the conversion mechanisms.

Rotary movement of the shaft 118 is regulated by a detent wheel 132 splined to the shaft 118 and situated within the interior of the plate 106. A plug 134 provided in the left side of the plate 106 as viewed in Figure 5, locks the detent wheel 132 in the interior of the plate 106. This detent wheel is provided with notches engaged by a suitable ball element analogous to the ball element 82 of the embodiment of Figures 1 and 2, the notches being spaced a distance proportionate to the rotary motion imparted to the shaft 118 by the conversion mechanism.

The'rotary conversion mechanism on one side of the dual actuator is designed to actuate the shaft in one direction and the conversion mechanism on the opposite side of the dual actuator is designed to rotate the shaft 118 in the opposite direction. Slippage permitted by each clutch lining 72a when the associated bladder 112 Vis not under pressure permits the two rota-ry conversion mechanisms to operate substantially independently. Thus one of the conversion mechanisms may be employed to repeatedly rotate the shaft 118 in a stepwise manner in a given directio-n without interference from lthe other conversion mechanism.

Although the preferred embodiment of the device has been described, it will be understood that within t-he purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

The invention having been thus described, the following is claimed:

1. In a iluid powered actuator device for imparting movement to a shaft, said device including a housing provided with a generally cylindrical chamber, said shaft passing axially through said chamber, and expansible means disposed in said chamber responsive to fluid under pressure for delivering an axial thrust, the improvement wherein said expansible means includes an elastomeric bladder having the shape substantially of a toroidal ring and having a continuous open seam in its outer periphery parallel to the plane thereof, said housing comprising two parts separable along a juncture occupying a plane normal to the axis of said cylindrical chamber, said bladder being disposedI in said chamber in encircling relation Vto' said shaft with its seam seated'in the juncture of said yseparable parts, means securing said parts in compressive engagement along said juncture to close the seam in said bladder, and means providing a fluid conduit passing through the wall of said housing into said bladder for delivery `of fluid under pressure thereto. f

2. In a iluid actuator device for imparting movement to a shaft selectively in opposite directions, said device including a pair of housing members each provided with `a cylindrical chamber and supported with their chambers 6 boring leading from each side thereof to the exterior of said device, a hollow pin press-fitted in each boring in said base member, there being one said pin projecting from each side of said base member and penetrating into the adjacent bladder, each said pin having an annular flange projecting therefrom within the adjacent bladder compressing the wall of the bladder against the side of the base member to effect a seal therewith.

3. In a lluid powered actuator device, a housing having a cylindrical cavity, a shaft journalled in said housing and passing axially through said cavity, an expansible toroidal bladder encircling said shaft adjacent one end of said cavity, means for conveying fluid under pressure to said bladder, and means enclosing said bladder and cooperating therewith to form an expansible chamber, said means comprising a pair of plates positioned for sliding axial movement in said cavity adjacent said bladder, and a sleeve surrounding said shaft and passing through said bladder, said plates having central apertures through which said sleeve passes, one plate having a central aperture snugly fitting said sleeve and having an outer pen'phery spaced from the cylindrical wall of said cavity, the other plate having a central aperture spaced from the periphery of said sleeve and rhaving an outer circular periphery snugly tting the cylindrical Wall of said cavity.

4. In a iiuid powered actuator device; a toroidal bladder, and means providing an expansible chamber for said bladder comprising a housing having a cylindrical chamber, said housingsupporting a cylindrical member extending coaxially into said chamber, said bladder being disposed in said 4chamber in surrounding relation to said cylindrical member, and a pair of adjacent plate members journalled for axial movement on said cylindrical member adjacent said bladder, said bladder being confined between said plate members and an end wall of said housing, one plate member having a central aperture snugly fitting said cylindrical member and an outer periphery spaced from the inner wall-of said cavity, the other plate member having a central aperture loosely tting said cylindrical member and an outer periphery snugly fitting the inner wall of said cavity, the construci tion and arrangement being such that said plate members cooperate t-o coniine said toroidal bladder While remaining free to move axially within -said chamber to accommod-ate expansion and contraction movements of said bladder.

References Cited in the tile of this patent Kendig L. Apr. 21, 1959

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