US2315775A

US2315775A - Control valve

Info

Publication number: US2315775A
Application number: US393032A
Authority: US
Inventors: Arcey Alfred C D
Original assignee: MASON NEILAN REGULATOR CO
Current assignee: MASON NEILAN REGULATOR CO; MASON-NEILAN REGULATOR Co
Priority date: 1941-05-12
Filing date: 1941-05-12
Publication date: 1943-04-06
Anticipated expiration: 1960-04-06

Description

April 6, i943.

A. C. DARCEY CONTROL VALVE Filed May 12, 1941 I NVEN 1: R: ALFRED 0.1) ARCEY Patented Apr. 6, 1943 CONTROL VALVE Alfred C. DArcey, Milton, Mass., asslmor to Mason-Neilanltegulator 00., Boston, Mass, a voluntary trust of Massachusetts Application May 12, 1941, Serial No. 393,032

15 Claims. (CL 137-139) This invention relates to valves for the con trol of fluids and particularly concerns an im-" provement in control valves of the type wherein a rotary valve member is employed to govern flow 4 through the valve and wherein the valve member is operated by a motor driven reciprocating mem-- ber in response to variations in the value of a power medium.

More specifically, the invention is adapted for use in connection with butterfly valves in which a rotatably mounted valve disc or flapper is positioned in respect to a valve port by means of a reciprocatable element, such as the stem of. a diaphragm or piston, and the invention relates particularly to improved means for converting the reciprocatory movement of the motor stem to a predetermined rotary movement of the flapper, whereby improved results in valve operation may be obtained, especially under conditions of high temperature. y

In connection with many kinds of process control, it may become necessary for butterfly valves to be subjected to widely varied temperature conditions, and it is not unusual for the valve body, through which the controlled fluid flows, and for the operating parts immediately associated there-' with to be subjected to temperature changes of 1000 F. or more. Where accurate control is demanded, therefore, the valve must .be adapted to function satisfactorily throughout a wide range of temperature variation.

To provide satisfactory operation under exacting conditions of process control, it is desirable that lost motion of the working parts be substantially eliminated in order that the port opening may be varied in accordance with the demand of the system, and further in order that an undesirable fluttering of the valve disc or flapper, resulting from lost motion, be avoided. I have found, however, that where lost motion is reduced to a minimum the operation of the valve is impaired .by reason of temperature changes. In valves of standard construction, it has become the practice to use certain well-known materials for the essential valve parts which have become v standardized by the trade because of their wear and corrosive resisting properties. A type of material commonly required is stainless steel and, therefore, it has been the practice to manufacture certain parts, such as the flapper stem or shaft, of a form of stainless steel suitable to the conditions. When it is noted that the coefiicient of expansion of stainless steel is substantially .00001 inch, per inch of shaft length, per degree F. of temperature change, it will be understood that a 10-inch length oi shaft subjected to a 1000 F. rise in temperature will increase its length by inch. For example, in a valve having 9. diaphragm or piston travel of 2 inches for imparting a turn to the flapper between closed and full open Positions, the error developed in the rotary position of the flapper {in respect to the reciprocatory position of the stem would be approximately 5 per cent. In other words, when the diaphragm or piston is at a given position in its range of travel, as determined by a condition responsive instrument or the like, the rotary position or the flapper will have an error of substantially 4 degrees which may seriously affect the accuracy of control, particularly when there is little or no flow demand, as when the valve is operating close to or on its seat. Furthermore, the parts may be subjected to considerable strain and the flapper may have a tendency to stick and thus impair the operation of the valve.

It is an object of this invention to provide a valve which will function equally well under low and high temperature conditions.

It is another object of this invention to provide a valve which will have substantially no lost motion, so that the valve opening demanded by the motor is strictly adhered to by the flapper.

It is still another object of this invention to provide means, in conjunction with a simple form of mechanism, whereby a given linear movement of a motor driven element imparts proportional rotary movement to a flapper irrespective-oi tern perature changes, and whereby the flapper is free to rotate between full open and closed positions to provide the port opening required in exact accordance with the demand. 4

It is still a further object of this invention to provide a ,valve which is not subjected to additional stresses due to the thermal expansion of valve parts.

These and other objects of my invention will be more fully understood from the'following description when taken in connectionwith the accompanying drawing in which:

Fig. 1 is a vertical section of a butterfly valve embodying my invention, the flapper being shown in closed position; i

Fig. 2 is an enlarged view, partially in section, of a portion of the mechanism shown in Fig. 1;

Fig. 3 is a horizontal section taken on line 3-4 of Fig. 1; and

Fig. 4 is a view similar to Fig. 3 showing the flapper in partially open position.

Having reference to the drawing, there ---is shown at In a butterfly valve body of standard flanged construction which is adapted for connection with piping, not shown, in which fluid flow is to be governed. The body It, is provided with the usual inlet and outlet chambers II and I2 respectively which, as herein shown, are connected by a port defined by semi-circular seating portions l3 and I4 disposed at opposite sides of the port. Means for controlling flow through the port may be in the form of a flapper l5, comprising a disc shaped member having an enlarged portion l1, through which is an opening for receiving a flapper shaft i6 which may be secured to the flapper by means of pins IS. The shaft I3 projects into a recess 26 at the lower end of the body having a closure plug 2|, and extends through a bore 22 with which the upper portion 23 of the body is provided, suitable guide bushings 24 and 25 respectively being supplied within which the shaft is free to rotate. A collar 26 is set. into the lower portion of the flapper at the axis of the shaft |3 which engages the upper surface of the guide bushing 25 and serves to determine the vertical position of the flapper within the port. The parts are preferably so arranged that when the flapper I6 is in closed position, as shown in Figs. 1 and 3, the circumferential edges of two opposite side faces of the flapper engage the seating portions l3 and I4 to provide a relatively tight shut-ofi.

Secured to the upper portion 23 of the body by means of studs 30 is an air cooled bonnet 3| having a cylindrical portion 32 which projects into a corresponding recess in the body portion and serves to center the bonnet in respect to the axis of shaft l3. Located axially of the bonnet 3| is an opening through which the shaft l6 extends, said opening being enlarged at 33 to receive suitable packing 34 and a gland 35 with its gland nut 36, the last mentioned member being threaded into a cylindrical extension 31 with which the bonnet 3| is provided. The gland nut 36 is centered in an opening 38 in the lower portion of an intermediate yoke 40 which is recessed to receive the cylindrical extension 31 and is secured to the bonnet 3| by a flange 21, with which the bonnet is provided, and by studs 4|.

The intermediate yoke 46 supports a cylindrical spring case 50, herein shown integral therewith, having a flange at its upper end to which a motor generally indicated at 52 is secured by studs 53. The motor 52 may comprise a pair of flanged members 54 and 55 and 9. diaphragm 56 secured at its edge between the flanges by means of bolts 51. Engaging the lower side of the diaphragm is a button 53 having a centrally disposed boss 59 which is threaded to the reduced end 60 of a diaphragm stem 6|, the latter being provided with a combined stem guide and spacer 62 which is slidably mounted in a suitable opening in a boss 63 on the lower diaphragm chamber member 54. Within the spring case 50 is a multiple spring 64 which is retained between an upper spring button 65 and a,lower spring button 66, the former being enga'ged by a thrust bearing race member 61 which is in, turn engaged by the stem guide 62 and the latter being threaded on a sleeve member 68, more fully hereinafter to be described, within which =the diaphragm stem 6| is slidably mounted and which together with its flange 69 serves as a thrust member for the lower spring button 66. Suitable stops for limiting the movement of the diaphragm 55 are provided by the diaphragm button boss 59, which engages the boss 63 on the lower chamber member 54 to limit its downward movement, and by upper race member 61, which engages the lower surface of chamber member 54 to limit its upward movement. The upper diaphragm chamber member 55 and diaphragm 56 serve to define a pressure chamber to which operating fluid under pressure may be admitted through a suitable pipe connection I0, it being understood that the diaphragm is biased downwardly on an increase in pressure and is biased upwardly on a decrease in pressure under the influence of the spring 64. While I have herein described a form of reciprocating motor, it will be understoodthat any well-known type of motor may be employed for the purpose of affording a reciprocating motion to the stem 6| in response to changes in controlled condition value.

Means for translating a reciprocatory movement of the diaphragm stem 6| to a predetermined rotary movement of the flapper shaft It may be in the form of a cylindrical member 15 having an opening therein within which the lower end of the valve stem is received. The cylindrical member 15, which may be conveniently referred to as a motion translating member, is rotatably mounted in a guide member 16 at the juncture of the intermediate yoke 40 and the spring case 50, and is provided with ball bearings 11, of which the flange 69, referred to above, forms the upper race member, and a washer 13 in the guide member 16 forms the lower race member. The motipn translating member 15 is provided with a pair of oppositely disposed semi-spiral slots 18 through which pins 13 secured to the stem 6| extend, the outer ends of the pins being received within vertical slots 80 formed in the intermediate yoke member 46. The spiral slots 18 are so arranged that when the stem 6| moves between its uppermost position and its lowermost position, under the influence of changes in pressure in the diaphragm chamber as opposed by the spring 64, the cylindrical member 15 together with the spring assembly,

, including multiple spring 64 and associated spring buttons 65 and 66, is rotated The lower end of the cylindrical member is connected with the shaft l8, in a manner to be described, so that when the stem BI is at the lower end of its travel, the flapper disc l5 engages the seats l3 and I4 and the valve is closed, and when the stem moves to the upper end of its travel, the flapper is rotated 90 to its open position to provide maximum flow through the valve body I0.

I have found that this construction is a practical means for transmitting movement from the reciprocating stem 6| to the rotary shaft l6 without substantial lost motion between theparts. Furthermore, adequate power may be delivered to the flapper by a relatively light motor for, by means of the slot-pin arrangement, a considerable mechanical advantage may be afforded in favor of the motor. Furthermore, I

have found that a flapper member positioned in this manner does not flutter under turbulent flow conditions as is characteristic of many types of construction due to 10st motion defects.

In practice, I preferably use a relatively large pitch on the cylindrical member for the purpose of obtaining a considerable mechanical advantage in favor of the motor 50 that small unit variations of diaphragm pressure will be responded to. Because of the multiplication of power, there is a possibility of damaging either the flapper, or shaft, or both, unless the downward movement of the diaphragm is limited when the flapper seats. It has been the practice, therefore, when the valve i assembled, to apply pressure to the diaphragm until it reaches its lower limit of travel as determined by the engagement of diaphragm boss 59 with lower chamber member boss 63. With the shaft I8 at the rotary position corresponding to the vertical position of the diaphragm stem iii, the flapper I is adjusted in relation to the shaft until it is tightly in contact with the port seats [3 and I4. The flapper is then secured to the shaft by the pins IS. The parts are preferably so arranged that the pins 19 are not at the ends of the spiral slots 18 both when the flapper is seated and when it is in open position in order that the diaphragm steps may serve as the sole limits of diaphragm movement.

While the construction hereinabove described is a practical mean of operating the flapper by a reciprocating motor without lost motion, it does not lend itself to temperature changes. When the shaft I8 is rigidly secured to the cylindrical member 15, the established relative position of the parts is varied by changes in temperature due to the expansion and contraction of the shaft as hereinabove set forth. In the example citedabove, if the mean average temperature of a -inch length of shaft is raised 1000 F. a a. inch increase of stem length will move the cylinder in relation to the diaphragm stem BI and will rotate the cylinder 15 and with it the shaft l8 and flapper IS in a. counterclockwise direction, as viewed in Figs. 3 and, 4, thus, varying the position of the flapper in respect to the diaphragm stem. If the flapper is in its seated position, as shown in Fig. 3, it will be rotated substantially 4 /2 degrees to a position corresponding to that indicated in Fig. 4 wherein the valve, herein disclosed, is shown substantially at a 4% degree opening. Therefore, while the valve can be closed-by the motor under certain temperature conditions as, for

example, the temperature at which the valve is assembled, it cannot be closed by the motor under higher temperature conditions and a flow varying with the increase in temperature will occur. Thus, when the process demand calls for a control of flow requiring the valve to be at or in close proximity to its seat, the valve will fail to function as intended and undesirable results will be obtained.

In order to overcome the difficulties outlined above, I provide a splined connection, more clearly shown in Fig. 2, between the flapper shaft l8 and the cylindrical member I5 in the form of oppositely disposed slots 85, provided in the wall of the shaft in parallel with the shaft axis. and key members 86 correspondingly placed on I per, such as lever arms, links and the like, and

the inner wall of the cylindrical member which A are adapted to be received within the slots in the shaft. The key members make a close sliding fit with the slots so that while no torsional lost motion is permitted, the parts are free to have independent axial movement without imparting rotary movement to the cylindrical member and flapper. By means of this arrangement, I have eliminated both the compressional and torsional stress which would otherwise occur under changes in temperature of the controlled fluid. I regard this arrangement combined with the cylindrical member 15 as an important development in the art, for I am able to obtain a direct straight-through connection from the motor stem iii to the flapper shaft l8, the parts being axially aligned and of compact, simple (5 construction. This device may be designed for any mechanical advantage required by the flow conditions, without a tendency to over-stress the parts or to vary the rotary position of the flapper in respect to the reciprocatory position of the motor stem. Furthermore, I have avoided the use of a plurality of pivotally mounted members for operatively connecting the motor to the flaptherefore, have eliminated the lost motion effects which are inherent to devices of that type.

While I have herein described in detail a preferred form of device embodying my invention, it is to be understood that the individual parts may be modified without departing from the spirit of the invention as defined in the, appended claims. 1

I claim:

1. In a valve forgoverning the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in responseto'variations in magnitude of a power medium, a. rotatable valve member cooperating with said port, a rotatable driven member in operative connection with said valve member, a rotatable nonreciprocatory motion translating member in opera ative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement of the latter, and means providing for axial expansion of at least one of said rotatable members while maintaining the rotary position established by the power device.

2. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in response to variations in magnitude of a power medium, a rotatable valve member cooperating with said port,

- a rotatable driven member in operative connection with said valve member, a rotatable nonreciprocatory motion translating member in operative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement of the latter, and means providing for axial expansion of said driven member while maintaining the rotary position established by the power device.

3. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in response to vari-,

ations in magnitude of a power medium, a rotati able valve member cobperating with said port, a rotatable driven member in operative connection with said valve member, a rotatable nonreciprocatory motion translating member in operative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement of the latter, and means between said motion translating member and said driven member providing for axial expansion of said driven member while maintaining its rotary position as established by the power device.

4. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in response to variations in magnitude of a power medium, a rotatable valve member cooperating with said port, a rotatable driven member in operative connection with said valve member, a rotatablenons ations in magnitude of a power medium, a rotatable valve member cooperating with said port, a rotatable driven member in operative connection with said valve member, a rotatable nonreciprocatory motion translating member in operative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement of the latter, and means including a key and slot connection providing for axial expansion of said members while maintaining the rotary position established by the power device.

6. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having anon-rotatable reciprocatory element movable in response to variaticns in magnitude of a power medium, a rotatable flapper cooperating with said port, a driven member rotatable about its longitudinal axis connected with said flapper, and a rotatable nonreciprocatory motion translating member in operative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement-of the latter, one of said members having a slot therein disposed in parallel with the axis thereof and another or said members having a part in engagement with said slot forming'an axially sliding rotary driving connection providing for axial expansion of said members.

7. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in response to variations in magnitude of a power medium, a driven member having a longitudinal axis about which it is adapted to rotate, a valve member rotatable with said driven member to govern flow through said port, a rotatable non-reciprocatory motion translating member having an axis aligned with the axis of said driven member in operative con-' ncction both with said reciprocatory element and said driven member for converting linear movement of the former to rotary movement of the latter, and means providing for axial expansion of at least one of said rotatable members while maintaining the rotary position established by the power device.

8. In a valve for governing the flow of fluids having a body defining a passage including a port, a power device having a non-rotatable reciprocatory element movable in response to variations in magnitude of a power medium, a driven member having a longitudinal axis about which it is adapted to rotate, a valve member rotatable with said driven member to govern flow through said port, a rotatable non-reciprocatory motion translating member in operative connection both with said reciprocatory element and with said driven member for converting linear movement of the former to rotary movement of the latter, the axes of said reciprocatory element and rotatviding for axial expansion of at least one of said rotatable members in respect to another.

able members being coincident, and means pro- 9. In a valve for governing the flow of fluids having a body defining a passage including a port, the combination with a power device and a rotatable valve cooperating with said port, of means for transmitting movement from said power device to said valve, including, a reciprocatory member operated by said power device, a rotatable driven member in operative connection with said valve, and a rotatable cylindrical member into which said reciprocatory member and said driven member extend,-one of said members having a spiral slot therein, another of said members having a part cooperating with said slot and the other of said members being in operative connection with said cylindrical member whereby linear movement of said reciprocatory member is converted to rotary movement of said driven member, and means providing for axial expansion of at least one of said rotatable members while maintaining the rotary position established by the power device.

10. In a butterfly valve for controlling the flow of fluids having a body defining a fluid passage including a port, the combination with an element reciprocatable in response to variations in operating pressure, a support on said valve body on which said element is mounted having a slot therein extending longitudinally in the direction of movement of said element, and a part carried by said element extending transversely of the axis of movement thereof, of a plurality of members, including, a flapper member rotatable to control the flow of fluid, a rotatable shaft member in operative connection with the flapper member to impart rotary motion thereto, a member in operative connection with the shaft having a slot therein positioned adjacent to the first slot but being inclined relatively thereto, the

part carried by said reciprocatable element engaging within said two slots whereby movement of the element will cause said part carried thereby to move longitudinally along said slots and thereby rotate the shaft member, and means providing for axial expansion of one of said plu rality of rotatable members in respect to another while maintaining the rotary position established by said operating pressure responsive element.

11. In a butterfly valve for governing the flow of fluids including a body defining a port having oppositely disposed semi-circular seating portions, a power device including a reciprocatory element movable in response to changes in operating pressure, a non-rotatable stem reciprocated by said power device, a flapper rotatable for engagement with said seating portions to effect closure of said port, a rotatable shaft to which said flapper is secured, a rotatable non-reciprocatory motion translating member in operative connection with said stem and with said shaft for converting linear movement of the former to rotary movement of the latter, and means providing for expansion of said rotatable shaft while maintaining the position of the flapper in respect to said port which is established by the power device.

12. In a butterfly valve for governing the flow of fluids having a body defining a passage including a port, a power device including a reciprocating element movable in response to variations in fluid operating pressure, a stem reciprocated by said element, a flapper rotatable to govern flow through said port, a rotatable shaft to which said flapper is secured having an axis coincident with the axis of said stem, a motion translating member comprising a rotatable cylinder having an axis coincident with the axes of said stem and shaft one end of which is associated with said stem and the other end of which isassociated with said shaft, a yoke secured to said body on which said power device is mounted having a slot therein extending longitudinally in the direction of movement of said stem, said cylinder having aslot in the wall thereof positioned adjacent said first slot but inclined relative thereto, a part carried by said stem engaging within said two slots whereby linear movement of the stem will cause said partcarried thereby to move longitudinally along said slots and thereby rotate the cylinder, and a rotary driving connection between said cylinder and said shaft including means providing for axial expansion of said shaft while maintaining the rotary shaft position established by the power device.

13. In a butterfly valve for governing the flow of fluids having a body defining a passage including a port, a power device including a reciprocating element movable in response to variaaticns in fluidoperatlng pressure, a stem reciprocated by said element, a flapper rotatable to govern flow through said port, a. rotatable shaft to which said flapper is secured having an axis coincident with the axis of said stem, a motion translating membercomprising a rotatable cylinder having an axis coincident with the axes adjacent said first slot but inclined relative thereto, a part carried by said stem engaging within said two slots whereby linear movement of the stem will cause said part carried thereby to move longitudinally along said slots and thereby rotate the cylinder, said cylinder and shaft comprising a pairof rotary driving memhers one of whi'ch has a slot in parallel with the axis thereof and the other of which has a part which cooperates with said slot to provide for axial expansion of said shaft.

14. In a butterfly valve for governing the flow of fluids having a body defining a port, a power device including a structure deflning a pressure chamber one wall of which is formed by a flexible diaphragm, yielding means urging said diaphragm in a direction opposed by pressure in said chamber, a stem reciprocated by said diaphragm, a flapper rotatable to effect closure of said port, a rotatable shaft to which said flapper is secured, a motion translating member in operative connection with said stem and with said shaft for converting linear movement of the former to rotary movement of the latter, a stop for limiting the valve closing movement of said diaphragm to a position at which said port is closed by said flapper, and means provided for expansion of said rotatable shaft while maintaining the position of the flapper in respect to said port which is established by said diaphragm.

15. In a butterfly valve for governing the flow of fluids including a body defining a port having oppositely disposed semi-circular seating portions, apower device including a structure defining a pressure chamber one wall of which is formed by a flexible diaphragm, yielding means urging said diaphragm in a direction opposed by pressure in said chamber, a stem reciprocated by said diaphragm, a flapper rotatable for engagement with said seating portions to effect closure of said port, a rotatable shaft to which said flapper is secured, a motion translating member in operative connection with said stem and with said shaft for converting linear movement of the former to rotary movement of the latter, a stop for limiting the valve closing movement of said diaphragm to a position at which said seating portions are engaged by said flapper, and means provided for expansion of said rotatable shaft while maintaining the position of the flapper in respect to said port which is established by said diaphragm.

ALFRED C. DARCEY.