US3253517A - Transducer - Google Patents

Description

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May 31, 1966 A 7' TOR/VE YS United States Patent() 3,253,517 TRANSDUCER James W. .lohn and Frederick R. Watson, Rochester, N .Y., assignors' to Eastman Kodak Company, Rochester, NY., a corporation of New Jersey Filed July 29, 1963, Ser. No. 298,300 Claims. (Cl. 9213) The present invention relates to a transducer and, more particularly, to a valve actuator suitable for converting pneumatic or hydraulic pressure into rotary motion.

In the art of pneumatic or hydraulic operated actuators most of the equipments are complex, physically large and unreasonably expensive compared to the equipment operated. This is particularly true when the equipment being operated is a simple rotary valve. In some instances the actuator exceeds the cost of the valve by 2,000%. Moreover, available actuators usually have undesirable hysteresis loss characteristics because of complex linkages and the like that preclude their use for accurate valve modulation. Also because of the complexity of the parts in presently available actuators, the cost of maintenance is economically prohibitive.

Therefore, a primary object of our invention is to provide a simple, reliable, economical transducer.

A more specic object of our invention is to provide a simple and reliablepressure operated valve actuator arranged to have an absolute minimum of hysteresis loss characteristics.

ln accordance with our invention a cylinder has placed therein a piston driveable a predetermined stroke in accordance with the pressure differential thereacross. Although the piston may be actuated by any fluid, including air and hydraulic fluid, we will refer to it hereinafter as a hydraulically operated system. The piston of one embodiment of this hydraulically operated system contains a central aperture having a helical inner surface suitable for engaging a helical drive shaft. The stroke of the piston is arranged so that at least a portion of the drive shaft is continuously engaged by the helical surface of the piston aperture whereby longitudinal movement of the piston rotates the shaft. The outer end of the shaft is provided with a socket or the like for engaging the device, such as a valve stem, which is to be operated. The piston itself is non-rotatably secured to the opposite end of the cylinder by means which is adjustable to control its initial angle of attack.

The subject matter which is regarded `as our invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, as to its organization and operation together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing in which:

FIG. 1 is a simplified top plan View of the transducer of our invention;

FIG. 2 is a cross-sectional view taken along line 2-2 o f FIG. l showing one embodiment of the present invennon; and

FIG. 3 is a cross sectional view taken along line 3-3 of FIG. 2.

Referring now to the drawing, wherein like numbers refer to similar parts, we have shown in FIG. 1 an end plate having a tapped fluid aperture 11 therethrough and mounting feet 12 thereon. Coaxial with the end plate 10 is a guide shaft 14 having an adjustable guide key or yoke 15 secured therearound with the guide key being provided with a tangential slot 16 engageable by locking assembly 18 illustrated as a bolt and lock washer arrangement. Thus the guide shaft 14 is securable in a plurality of angular positions in accordance with the set- Patented May 3l, 1966 ICC of bolts 22 to tightly secure the annular sleeve 24 therebetween. Because of the fact that we usually prefer to maintain pressure in the system to assure predetermined location of a piston 26 within the cylinder we have also provided sealing means in the form of O-rings 28. at each end of the annular sleeve 24. Obviously, other means such as gaskets or lsealing by solder, or glues could be used in place of the O-rings 28. As is apparent from the above enumerated parts, fluid pressure is provided selectively by a fluid supply means 29 to the apertures 11 and 21 to regulate the position and force obtained by the piston 26.

The piston 26 is provided with similar fluid seal means in the form of O-rings 30 resulting in a hydraulic seal between the outer surface of the piston 26 and the inner surface of the sleeve 24. At such times as air is the fluid utilized for moving the piston 26, a felt wick 32 also is provided in the outer surface of the piston 26 to continuously lubricate the surfaces being engaged by the O-rings 30 to both facilitate motion of the piston 26 and to assure a minimum of fluid loss. As illustrated, the piston 26 is fabricated from two pieces of machined metal. However, we contemplate that most of these pistons 26 will be cast, as in the case of similar parts of internal combustion engines.

A central axial portion of the piston 26 is provided with a recess 33 in what lmay be termed its leading surface. In a preferred form of our invention, this recess is partially lled with a coaxial plastic or metal insert 34 having a helically grooved inner recess surface 35 which matingly engages a coaxial helical drive shaft 36. As indicated in the drawing, the shaft 36 terminates at 37 to provide space for movement of the piston 26 toward the end plate 2li whereupon the shaft substantially lls the recess defined by the surfaces 35. A simple molding technique is to carefully center the shaft 36 in the recess 33 and then mold the insert 34. Of course, the surfaces must be prepared so that the insert adheres to the recess 33, and not to the shaft 36. Knurling and lubricants will accomplish suitable adhesive deferential as will the use of press lit pins protruding from the inner surface of the recess 33j In order to prevent excessive size in the cylinder of our invention, we prefer that the full stroke of the piston 26 accomplish no more than rotation of the shaft 36 during a two inch stroke' of the piston 26. Such rotation is more than adequate for operating many valves, of a standard type often used in bathrooms today.

The drive shaft 36 is rotatably supported in a pair of coaxial thrust ball bearings shown at 38 with a collar 40 therebetween being secured to the shaft 36 to prevent longitudinal movement thereof. The collar 40 is compressed between the thrust ball bearings 38 by a cap 41 secured to the end plate 20 by bolts indicated at 43. O-rings 42 prevent loss in the region of the thrust bearings 38 of fluid from the chamber within the cylinder. The outer end of the shaft 36 is provided with a socket 44 arranged to mate with the end of a valve stem 46 or the like.

At the other end of the cylinder the guide shaft 14 is integrally connected to a bifurcated guide yoke 48 which engages flat outer surface portions 49 of the central portion 50 of the piston 26. The mating curved surface of the yoke 48 is shown more clearly in FIG. 3. By using a bifurcated guide yoke 43, fluid is able to llow to and from the region of the aperture 11 and the space near the end 51 of the central portion 50. Since the yoke 48 is open at the sides between the bifurcations, no fluid is trapped between the yoke and the piston 26. Thus vaporlock is prevented. Similarly a bleeder port 52 is provided in the end 51 of the central portion 50 leading from the recess 35 to the chamber between the piston 26 and the end plate 20 to facilitate motion of the piston 26 relative to the shaft 36 without excessive build-up of pressure or vacuum in the system. Depending on the tolerances of the above mentioned molding technique, the bleeder port 52 may be omitted. f

When the angle of attack of the yoke 48 is established in accordance with a proper setting of the valve stem 46, the yoke 1S and the locking assembly 18 is tightened in place and another lock nut 53 is tightened to assure a tight engagement between the bifurcated guide yoke 4S and an additional seal means in the form of an O-ring 54. Thus the yoke 4S is positioned and secured to the end plate i0 to prevent further rotation of the piston 26 during its driving of the shaft 36. A stroke upper limit bolt 56 is also provided to limit the stroke of the piston 26 between the end plates 1G and 20 in accordance with yits adjustment. When proper adjustment is attained, as by driving the bolt S6 further into the recess of the yoke 4S, this bolt 56 is also locked in place by a lock nut 58. This results in a precise control of the maximum opening of valve which may be quite critical when controlling gas llow.

While we have shown and described a particular embodiment of the present invention, other modifications may occur to those skilled in the art. For instance, this simple and economical transducer may be used in many applications such as Windshield wiper blade drives, limited stroke rotary feed mechanisms and the like. Of course, transducers should be sized in accordance with work function. We intend, therefore, to have the appended claims cover all modications which fall Within the true spirit and scope of our invention.

We claim:

1. A transducer suitable for hydraulically operating a rotatable valve, comprising:

a cylinder provided with liuid ports near each end;

a piston residing within the cylinder and movable longitudinally therein, said piston having a central recess open at only one end whereby there is no fluid passage therethrough;

positioning means secured to one end of said cylinder and co-operating with said piston to prevent rotation during longitudinal motion thereof;

a locking arrangement for said positioning means including an adjustable key member n onrotatably secured thereto which key is tangentially positionable according to the tolerances of the valve and is securable by a locking assembly;

a coaxial helical drive shaft extending from the other end of the cylinder a sucient distance to have at least a portion thereof continuously reside within a mating helical cavity provided in the center of the L0 central recess of said piston, said drive shaft being rotatably supported in thrust bearing means whereby it will respond to longitudinal motion of said piston by rotation without longitudinal movement; and

socket means coupled to an external portion of said drive shaft for rotatably driving the valve.

2. A transducer suitable for hydraulically operating a rotatable valve, comprising:

a cylinder provided with lluid ports at each end and otherwise sealed to contain fluid therein;

a piston having no passage therethrough residing within said cylinder and movable longitudinally therein in response to fluid pressure differential thereacross;

means secured to one end of said cylinder and cooperating with said piston to prevent rotation thereof;

socket means rotatably coupled to a central external portion of said cylinder for rotatably driving the valve; and

a pair of members coaxial with said piston consisting of a helical drive shaft and a coaxial mating helical recess and arranged to have at least a portion of the shaft reside in the recess during all positions of said piston, one of said pair being non-rotatably secured to said piston and the other of said pair being nonrotatably secured to said socket means, whereby longitudinal movement of said piston will drivingly rotate said socket means, the recess being provided with a bleeder vent communicating with the portion of said cylinder containing the drive shaft.

3. A rotary actuator comprising:

a cylinder provided with fluid ports at each end forselectively admitting fluid thereto;

a piston movable longitudinally in said cylinder in response to relative lluid pressures acting thereon and having a central helical cavity;

a yoke secured within one end of said cylinder and engaging said piston to prevent rotation thereof:

a helical shaft mating with and rotatable by the helical cavity of said piston;

drive means external to said cylinder and drivably by said helical shaft; and

means for securing said yoke in a plurality of positions to establish the initial position of said piston.

4. A rotary actuator as in claim 3 wherein a means is provided to establish the maximum stroke of said piston in accordance with the requirements of the drive means.

5. A rotary actuator as in` claim 3 provided with a bleeder vent communicating between a closed end of the helical cavity and the portion of said cylinder housing said helical shaft.

Refercnees Cited by the Examiner UNITED STATES PATENTS 1,179,893 4/1916 Buckman 92-31 X 1,781,189 ll/l930 Nilson et al 92-31 X 1,951,030 3/1934 Nardone 91-53 2,055,674 9/1936 Smith 92-33 2,117,225 5/1938 Stein 92-33 2,800,885 7/1957 Panissidi 92-13 2,974,646 3/1961 Miller et al 92-33 3,146,681 9/1964 Sheesley 92-13 3,160,077 12/1964 Ribeiro 92-13 SAMUEL LEVINE, Primary Examiner.

RICHARD B. WILKINSON, Examiner.

H. G. SHIELDS, I. C. COHEN, Assistant Examiners.

Claims (1)

1. 2. A TRANSDUCER SUITABLE FOR HYDRAULICALLY OPERATING A ROTATABLE VALVE, COMPRISING: A CYLINDER PROVIDED WITH FLUID PORTS AT EACH END AND OTHERWISE SEALED TO CONTAIN FLUID THEREIN; A PISTON HAVING NO PASSAGE THERETHROUGH RESIDING WITHIN SAID CYLINDER AND MOVABLE LONGITUDINALLY THEREIN IN RESPONSE TO FLUID PRESSURE DIFFERENTIAL THEREACROSS; MEANS SECURED TO ONE END OF SAID CYLINDER AND COOPERATING WITH SAID PISTON TO PREVENT ROTATION THEREOF; SOCKET MEANS ROTATABLY COUPLED TO A CENTRAL EXTERNAL PORTION OF SAID CYLINDER FOR ROTATABLY DRIVING THE VALVE; AND A PAIR OF MEMBERS COAXIAL WITH SAID PISTON CONSISTING OF A HELICAL DRIVE SHAFT AND A COAXIAL MATING HELICAL RECESS AND ARRANGED TO HAVE AT LEAST A PORTION OF THE SHAFT RESIDE IN THE RECESS DURING ALL POSITIONS OF SAID PISTON, ONE OF SAID PAIR BEING NON-ROTATABLY SECURED TO SAID PISTON AND THE OTHER OF SAID PAIR BEING NONROTATABLY SECURED TO SAID SOCKET MEANS, WHEREBY LONGITUDINAL MOVEMENT OF SAID PISTON WILL DRIVINGLY ROTATE SAID SOCKET MEANS, THE RECESS BEING PROVIDED WITH A BLEEDER VENT COMMUNICATING WITH THE PORTION OF SAID CYLINDER CONTAINING THE DRIVE SHAFT.

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