US3702091A - Valve actuator means - Google Patents

Abstract

Improved fluid-operated valve actuator means for rotating a valve shaft in opposite directions through a given angle (preferably, 90* in the case of a quarter-turn valve). The invention is characterized by the provision of cam means connected with the output shaft and arranged in a chamber between a pair of freely movable operating pistons. When one end of the chamber is pressurized, the corresponding piston applies an operating force to the cam to rotate the cam and the output shaft through the given angle. In one embodiment, reversing valve means are provided for reversing the ends of the chamber that are pressurized and vented, respectively. In a second embodiment, one end of the chamber is alternately pressurized and vented, respectively, to achieve the desired rotation of the output shaft, the other end of the piston being enlarged to define a pressure fluid reservoir operable to return the output shaft to its initial position. In a third embodiment, spring means assist in returning the output shaft to its initial position.

Description

[451 Nov. 7, 1972 [54] VALVE ACTUATOR MEANS [72] Inventor:

[73] Assignees: Societe Argenton; Societe Anonyme,

Luxemburg, Luxembourg [22] Filed: April 27, 1970 [21] Appl. No.: 32,121

Jean Viaud, Paris, France [30] Foreign Application Priority Data April 28, 1969 France ..6913427 [52] US. Cl ..92/73, 91/399 [51] Int. Cl ..F01b 1/02 [58] Field of Search ......92/73, 68, 138

[56] References Cited UNITED STATES PATENTS 3,614,913 10/1971 Clark ..92/138 1,774,087 8/1930 Dunn ..92/73 2,614,540 10/1952 Morton ..92/73 FOREIGN PATENTS OR APPLICATIONS 602,982 3/1960 ltaly ..92/73 Primary Examiner-Paul E. Maslousky Attorney-Lawrence E. Laubscher [57] ABSTRACT Improved fluid-operated valve actuator means for rotating a valve shaft in opposite directions through a given angle (preferably, 90 in the case of a quartertum valve). The invention is characterized by the provision of cam means connected with the output shaft and arranged in a chamber between a pair of freely movable operating pistons. When'one end of the chamber is pressurized, the corresponding piston applies an operating force to the cam to rotate the cam and the output shaft through the given angle. In one embodiment, reversing valve means are provided for reversing the ends of the chamber that are pressurized and vented, respectively. In a second embodiment, one end of the chamber is alternately pressurized and vented, respectively, to achieve the desired rotation of the output shaft, the other end of the piston being enlarged to define a pressure fluid reservoir operable to return the output shaft to its initial position. In a third embodiment, spring means assist in returning the output shaft to its initial position.

1 Claim, 4 Drawing Figures PME'N'TEDnnv 11912 3,702,091

SHEET 1 OF 3 TQM V1 mu! INVENTOR.

v A'TTDWY VALVE ACTUATOR MEANS This invention relates generally to automatic actuator means for quarter-turn valves, and more particu larly to valves which are operated by rotating the axis of the valve by a quarter turn, said actuator means being of the pressure fluid (gas or liquid) type.

Valve actuator means controlled by a fluid under pressure are known in the prior art, said actuator means including one or more pistons operable in a cylinder as controlled by a solenoid-operated control valve. However, most of these known devices are rather cumbersome. Generally, the rod of the piston (or pistons) is linked bilaterally with the axis of the valve, and therefore the apparatus must have large dimensions so as to be able to perform the maximum effort corresponding with the starting phase. The known actuator systems are further complicated in that there are no means for correction of the resistant torque of the valve, and such a correction system does not accurately conform to the variations of the resisting torque.

The primary object of the present invention is to provide a small actuator, using an arrangement permitting its adaption to all the resisting torques encountered during operation. The actuator means can furthermore be used on various types of valves by simply changing one member (specifically, a cam member) to which the force bringing about the rotation of the valve is applied.

A more specific object of the invention is to provide valve actuator means including, in a cylinder, a pair of free pistons that engage, by direct unilateral contact, a cam between the two of them, said cam being mounted on the valve control shaft in an eccentric fashion with respect to said shaft, so as to bring about the rotation of this shaft in one direction or the other when the pressurized fluid is introduced at one or the other extremity of the cylinder.

A further object of the invention is to provide valve actuator means including one or more of the following features:

a. A supplementary pressure (pneumatic or liquid) fluid reservoir is provided in one of the ends of the cylinder, and a small-diameter conduit alternately connects this end of the cylinder to the other end and to atmosphere, respectively, with the help of a pressureresponsive valve means so as to make it possible very progressively to establish sufficient return pressure on the end of the reservoir in order to obtain a single-action actuator;

b. A spring is introduced between one of the ends of the cylinder and the corresponding piston so as to provide a single-action actuator;

c. The profile of the cam corresponds to the variable effort which the valve requires for its operation depending upon the different positions of the valve member relative to its seat; and

d. The cam is provided with a very hard metal belt and the surface of each piston in contact with the cam is provided with an added self-lubricating portion consisting of hard substance.

Other objects and advantages of the invention will become apparent from a study of the following specification, along with several forrns of implementation, given here simply by way of example, without any limitations, and represented schematically in the attached drawings where:

FIG. 1 is an axial cross-section view of a valve actuator according to the present invention;

FIGS. 2 and 3 are axial cross-sectional views of two additional embodiments of the invention; and

FIG. 4 is a schematic view of the cam means used in a valve actuator according to the invention.

The valve actuator according to FIG. 1 essentially involves a cylindrical housing 1 in which are mounted two free pistons 2 and 3. Between these pistons there is arranged a cam member 4 which, for simplicity, is illustrated as having a circular configuration. The cam is secured to the control shaft 5 of a valve member (not shown). The center of the cam is eccentric with respect to the valve control shaft. The housing includes openings 6 and 7 which alternately conduct the pressure fluid through ducts 8 and 9 to the extremities of the chamber of housing 1 in accordance with the position of the solenoid-operated reversing valve means.

The two pistons 2 and 3 are freely supported in the cylinderv for longitudinal and rotational movement. Since there are no guide means, the periphery of each piston presents a rather large surface consisting of two annular flange portions 10 between which is provided a groove 11 for receiving packing means (not shown).

In operation, the cam 4 which operates the valve shaft rolls with a certain friction on the opposed surfaces 12, 12 of the pistons. In order to prevent wear and tear, the pistons are provided with a self-lubricating substance or they may have, on surfaces 12, an added disk consisting of hard self-lubricating substance, or a roller may be mounted in the center of the surfaces 12 to reduce the friction coefficient and to increase the yield.

The operation of the apparatus is very simple. The orifices 6 and 7 are connected in a known manner with the pressure source and sump (or vent), respectively, via conventional-solenoid reversing valve means. As the pressure fluid is supplied via orifice 6, the outside air is driven out through orifice 7. During the displacement in the direction of arrow F, for example, piston 2 pushes cam 4 which is forced to turn as a result of the eccentric position of its pivoting axis and the shaft 5 of the valve is consequently rotated. The operation of the solenoid reversing valve causes the shaft of valve 5 to turn in the opposite direction.

It is apparent that when the actuator is not under the influence of the moving fluid, the two pistons are entirely'free since they are not connected to the cam by a small rod, a rack, or any other connection, or to each other. One important consequence of this is that the actuator is automatically disconnected when it is no longer under the influence of the moving fluid, thus permitting very easy manual operation of the valve shaft (for emergency purposes, for example). In effect, the automatic actuator according to the invention can, in the known manner, present a shaft output end on the other side of the valve with respect to the cylinder so as to permit manual control of the valve in case the actuator does not function. While, for simplicity, the mechanical indicator of the position of the valve, as well as the possible contactors for the remote indication or remote registration of the position of the valve,

have not been illustrated, it should be mentioned that one of the advantages of this actuator is that it permits placement of the elements inside the actuator while keeping its size small.

According to the modification of the invention shown in FIG. 2, the actuator is designed to function in a single acting way when only one of the pistons is in direct contact with the source of pressure fluid. This arrangement is particularly advantageous when the valve, controlled by the actuator, does not require a holding torque to maintain the valve in the open or closed position. The housing .1 has been noticeably extended on one side to define a reservoir 13' on this side of the cylinder which is larger than the chamber 14' on the other side, when the pistons are, respectively, in the two extreme positions. Furthermore, a small-diameter conduit 15' connects reservoir 13 to chamber 14' through a pressure-responsive retaining valve consisting of a ball 16' which normally closes a small opening 17' communicating with chamber 14'.

Ball. 16', in its other extreme position, closes off a seat 18' made on a drill hole 19' leading to atmosphere. The ball thus' causes chamber 13' to be alternately connected with atmosphere and with chamber 14', respectively.

As we can see, the purpose of this arrangement is to avoid giving the actuator large dimensions. In effect, if

we use a spring or an additional compressed-air reservoir, it may be accomplished that, during the first stroke, it is necessary to use force not only to operate the valve but also to compress the spring or the return fluid. Furthermore, when a compressed'fluid is used for the return, the stored pressure energy must be sufficiently large that there will not be too great a pressure drop at the end of the return stroke.

The device operates as follows. Assume that the pistons are in the extreme right-hand position compressed air is introduced through inlet 20. The entire assembly then moves to the left, and since the cylindrical elements close the opening 17, the air which is in chamber 13' is driven out through conduit and escapes into the atmosphere through opening 19'. At the end of the stroke, the opening 17' is uncovered. The ball is projected toward its upper seat 18', and space 13' is filled progressively with compressed air in a relatively slow manner through conduit 15 which has a small diameter. In this way the fluid introduced at chamber l3'practically does not offer any resistance to the stroke of the pistons at the end of the operation.

At this moment, the controlled valve is completely opened or closed and the compressed air continues to arrive through inlet going to chamber 14', and it continuesto move toward chamber 13' through conduit 15' until the pressure is the same in chambers 13' and 14'. At this moment, the assembly is in balance under pressure and the valve is immobilized in its extreme position.

If the influx of, air through inlet 20 is terminated and inlet 20'. is placed in communication with the atmosphere, the compressed air accumulated in chamber 13 pushes the mobile device toward the right up to the other extreme position. Of course, a little bit of compressed air escapes through conduit 15' but this is of no importance to the operation because this conduit has a small diameter, calculated in such a manner that its flow speed will be small with respect to the speed of the piston.

On the other hand,.since chamber 13' is much larger than chamber 14', the compressed air accumulated in chamber 13 hasa' volume sufficient to cause the device to perform the return stroke without a very noticeable pressure drop. After the end of this opera-- tion, the two chambers 13' and 14 are at atmospheric pressure and we once again have equilibrium. It must be noted that, in certain cases involving quarter-turn valves, which are rather rare, by the way, it is necessary to exert an effortwhenthe two chambers are in communication with the atmosphere in order to keep the valve in position. Inthis case, it is easy to provide a spring on one side, exerting just the right complementary action necessary to keep the device butting against the other side of the cylinder. When the valve is in the other position, .the pistons may be provided with different diameters so as to obtain a differential effect when the two chambers 13' and 14 are under pressure; this. differential effect here applies the mobile assembly against a stop. Naturally, in the, case of the simple action, one can use a spring to bring about the return stroke.

FIG. 3 is a schematic illustration of such a version. For this purpose, cylinder 1" has been enlarged, as in the earlier case, so as to constitute sufficient space at 13" for one or more springs ,21", spring 21" being supported in a recess 22" contained in the piston 2", for example.In this case, there is only one pressure fluid inlet 20", with the fluid here working on piston 3".

The operation is alsovery simple in this case and the nozzle is connected alternately to the pressure source and to the air, respectively, with the help of a solenoidoperated control valve. Thus, when piston 3" has been moved toward the left due to the action of the fluid, as indicated in FIG. 3, spring 21" has been compressed. At that moment, it suffices to place inlet 20" in contact with atmosphere in order to have spring 21" expand, pushing the entire assembly toward the right, which causes the cam 4", and, consequently, valve shaft 5" to turn. While only one spring has been illustrated, it is obvious that several springs could be used, if desired.

In the schematic illustrations of FIGS. 1-3, the cam has been illustrated as having a circular configuration. In fact, it is preferable to have a cam with a profile corresponding to the variable effort required by the valve or its operation.

The profile of the cam can be calculated in a practically exact manner. In effect, for a constant air pressure, the force exerted on the cam is constant in terms of force and direction. The variation of the rotation torque is a function only of the point where the cam rubs on the moving piston. It thus suffices to say that the moving torque, which is a function of the position of the contact point of the cam is equal to the resisting torque of the valve which in turn is a function of its angle or rotation. Furthermore, it is also easy empirically to determine the best profile for the cam by successive approximations.

FIG. 4 shows such a cam, said cam being formed of light metal and including a belt in the form a plate spring 23 whose two extremities 24are clamped on a cavity 25 contained in the cam. The dot-dash line illustrates the zones of contact 26 of the cam with the pistons.

Of course, the versions-described above and shown in the attached drawings are given here only by way of simple examples without any restrictions, and it is apparent that one could modify the shape, arrangement,

nature, and mounting of its elements in any suitable fashion without deviating from the inventive concepts.

' What is claimed is:

1. Valve actuator means for rotating a valve operating shaft alternately in opposite directions through a given angle of less than 180, respectively, comprising a. piston and cylinder means including (1) a housing (1) containing a longitudinally extending cylindrical chamber, said housing including side and end walls; and (2) a pair of spaced pistons (2, 3) mounted for independent free reciprocatory movement longitudinally of said chamber, respectively;

b. a cam member (4) arranged in said chamber between said pistons, said cam member being contained in a plane colinear with the longitudinal axis of said chamber and having a non-circular cam profile designed to effect a desired non-uniform operation of the pistons, the profile surface of said cam member including a layer of hard metal (23);

. a valve operating shaft (5) journalled in said housing side wall and extending at one end within said chamber, said shaft being normal to said longitudinal plane and laterally offset from the longitudinal axis of said cylindrical chamber, said cam member being eccentrically arranged relative to and rigidly connected with said valve operating shaft; and

. means for supplying pressure fluid to a first end of said chamber between a first one of said pistons and the corresponding end wall to force said first piston into operating engagement with the surface of said cam member and thereby rotate said cam member in one direction through said given angle.

Claims (1)

1. Valve actuator means for rotating a valve operating shaft alternately in opposite directions through a given angle of less than 180*, respectively, comprising a. piston and cylinder means including (1) a housing (1) containing a longitudinally extending cylindrical chamber, said housing including side and end walls; and (2) a pair of spaced pistons (2, 3) mounted for independent free reciprocatory movement longitudinally of said chamber, respectively; b. a cam member (4) arrangEd in said chamber between said pistons, said cam member being contained in a plane colinear with the longitudinal axis of said chamber and having a noncircular cam profile designed to effect a desired non-uniform operation of the pistons, the profile surface of said cam member including a layer of hard metal (23); c. a valve operating shaft (5) journalled in said housing side wall and extending at one end within said chamber, said shaft being normal to said longitudinal plane and laterally offset from the longitudinal axis of said cylindrical chamber, said cam member being eccentrically arranged relative to and rigidly connected with said valve operating shaft; and d. means for supplying pressure fluid to a first end of said chamber between a first one of said pistons and the corresponding end wall to force said first piston into operating engagement with the surface of said cam member and thereby rotate said cam member in one direction through said given angle.

Images