US3091427A - Diaphragm valves - Google Patents

Description

y 8, 1963 H. w. BOTELER 3,091,427

DIAPHRAGM VALVES Filed Oct. 10; 1961 s Sheets-Sheet 1 INVENTOR. HENRY W. BOTELER ATTORN Y y 8, 1963 H. w. BOTELER 3,091,427

DIAPHRAGM VALVES Filed Oct. 10, 1961 3 Sheets-Shea HENRY w BOTELER ATTORNEY y 28, 1963 H. w. BOTELER 3,091,427

DIAPHRAGM VALVES Filed Oct. 10, 1961 3 Sheets-Sheet 3 42 M II F 76 I 30 4O 26 2 n -I I I 2 u 24 24 54 I -94 W r511 46 l8 n y 38 I I J 66 38 38b I 27 INVENTOR. HENRY W. BOTELER F IG. 4

ATTORNEY United States Patent 3,691,427 DIAPHRAGM VALVES Henry W. Boteler, East Greenwich, 11.1., assignor to Grinnell Corporation, Providence, R1, a corporation of Delaware Filed Oct. 10, 1961, Ser. No. 144,215 9 Claims. (iCl. ESL-77) This invention relates to improvements in diaphragm valves. More particularly it has to do with a diaphragm valve in which the flow passageway through the valve body is substantially straight and in which the diaphragm is of the type having a deeply bulged center portion extending, in the valve closed position, from an opening on one side of the body across the passageway and into seating engagement with the opposite side thereof.

For many years diaphragm valves as above-described have been popular because of the fact that their flow passageways are free from the interruptions and sudden changes in direction which characterize the more common weir-type diaphragm valves and globe valves.

In this same period, however, chemically inert plastic materials such as polytetrafluoroethylene have been widely employed for diaphragms in weir-type diaphragm valves because of their ability to resist corrosion by the fluids being handled.

The diificulty has been that although these inert plastics have been sulficiently durable, when formed into the shapes of diaphragms for valves of the weir-type, to withstand repeated flexing without rupture, formation of these plastics into diaphragms for weir-less valves has resulted in such severe distortion of certain areas of the deeply bulged diaphragm center portions that rupture occurs after a relatively small number of valve operations.

More particularly, in valves of the weir-less or substantially weir-less type, the diaphragm (which has hitherto been formed of rubber or rubber-like material in these valves) has accomplished closure by being pressed against a seating band on the body which has one end on the diaphragm opening flange surface on one side of the diaphragm opening and extends over the rim of the diaphragm opening, down a sloping wall portion to the bottom of the passageway, then up an opposite sloping wall portion to its other end on the diaphragm opening flange surface on the opposite side of the diaphragm opening. Whereas this pressing against the seating band on the sloping walls and on the bottom of the passageway has been accomplished by a compressor behind the diaphragm at these areas, it has not been possible to have the compressor also overlie the seating at the corner formed by the sloping walls and the diaphragm opening flange or to overlie the ends of the seating on this flange itself. The reason for this is that to close the valve the advance of the compressor toward the seating (in a direction along the diaphragm opening axis) achieves an adequate squeeze of the sloping sides of the diaphragm center portions against the sloping walls only after an amount of advance substantially greater than that required to squeeze adequately the diaphragm against the ends of the seating which are perpendicular to such axis; and it has not been found possible to overlie the seating ends with compressor portions which do not begin to squeeze the diaphragm thereagainst until after the diaphragm central portion has been partially squeezed. In other words the type of construction of these valves does not lend itself to the critical forming of a compressor which will begin to squeeze different portions of the diaphragm at different points in the compressor advance and which will have squeezed all portions equally at the end of the advance. Attempts along these lines have either failed or have been prohibitively expensive.

Patented May 28, 1963 "ice The solution to this problem has been to mold the rubber or rubber-like diaphragm so that without any distortion the deeply bulged cone-shaped central portion does not reach the bottom of the passageway and so that substantial stretching of the diaphragm material by the advance of the compressor is required to close the valve. This stretching draws the portions of the diaphragm which are adjacent to the opening flange and to the rim of the opening tightly enough against the seating at these locations to achieve a closure, and compressor portions overlying these diaphragm portions have been omitted. However, while this stretching technique has been satisfactory for weir-less diaphragm valves when resilient rubber or rubber-like diaphragms have been used, diaphragms made from certain of the chemically inert plastics will not recover their original molded shape after an initial stretching which is severe enough to accomplish valve closure in the manner described. The result of this is that subsequent closures cannot be achieved or that the diaphragms lose their imperviousness to the liquids controlled by the valve after such stretching.

I have discovered, however, that these difficulties are overcome to a surprising and unexpected degree when such a weir-less diaphragm valve is provided with a plastic diaphragm which is formed with sufiicient material in the bulged center portion so that this portion substantially engages the seating without stretching when the compressor is moved to close the valve and which diaphragm is provided with a separate reinforced backing cushion of rubber or rubber-like material having its center portion located between the compressor and the diaphragm and having its periphery clamped between the diaphragm periphery and the bonnet.

Unlike the bulged center portion of the plastic diaphragm the bulged center portion of the backing cushion is formed sufficiently short so that it must be stretched substantially by the compressor during valve closing to reach the point where it begins to squeeze the center of the plastic diaphragm against the seating. This stretching presses the plastic diaphragm firmly against the seating at the ends thereof where the compressor does not overlie these ends, but at the same time the plastic diaphragm is not itself stretched appreciably and therefore rupture is prevented.

This combination of an unstretching plastic diaphragm with a stretching reinforced rubber-like backing cushion is made possible in a preferred embodiment of the invention by a novel structure with which the diaphragm, backing cushion and compressor are connected together. Thus, in substantially all types of diaphragm valves, including the weir-less types, some connection is required between the diaphragm exposed to the fluid and the compressor so that when the compressor is withdrawn to open the valve it positively pulls the diaphragm with it. Experience has shown that the fluid pressure alone cannot be relied upon to move the diaphragm away from the seat to open position, and in some services this pressure is actually negative, that is, below atmospheric. The novel structure referred to comprises in general a connecting member which is secured to the center of the plastic diaphragm, which passes slidably through the center of the backing cushion and which is secured to the compressor. In accordance with a preferred embodiment of this invention a special lost-motion arrangement is provided where the connecting member is secured to the compressor so that a space exists between the plastic diaphragm and the backing cushion when both have their central bulged portions extending fully toward the seating and the backing cushion is unstretched. Thereafter tight closing of the valve is accomplished by moving the compressor to stretch the backing cushion into this space and into firm engagement with the plastic diaphragm. This stretching of the backing cushion squeezes the diaphragm at the ends of the seating and this firm engagement squeezes the diaphragm at the center of the seating.

A very beneficial result of this connecting arrangement is that the diaphragm and backing cushion can be installed in the valve without stretching the backing cushion or distorting the diaphragm or both during such installation. Thus, during assembly of a valve or replacement of a diaphragm the peripheries of the diaphragm and of the backing cushion must be registered between the bonnet and body flanges with each other and with these flanges. The above-referred-to special lost-motion connection enables the diaphragm and backing cushion to be installed without the distortion and stretch which would make such registering extremely difflcult.

Accordingly, it is an object of the present invention to provide a diaphragm valve of the weir-less, or sub stantially Weir-less, type having a diaphragm of chemically inert plastic material which is so formed that when it is extended into engagement with its seating it is substantially unstretched and further having a backing cushion [of rubber or rubber-like material which is so formed kind described in which the lost-motion connection passes s'lidable through the backing cushion and permits the backing cushion to move to a location spaced from the diaphragm.

Another object is to provide a diaphragm valve of the kind described in which in one position the backing cushion is substantially unstretched in a location spaced from the diaphragm and in which the diaphragm is at the same time substantially undistorted. Another object is to provide a diaphragm valve of the kind described in which the lost-motion connection has a novel structure associated with a side surface of the compressor for preventing rotation of the connection with respect thereto.

Another object is to provide a diaphragm valve of the kind described in which the plastic diaphragm has its thickness change in a novel way and in which the backing cushion has a diaphragm-engaging surface conforming to this change.

Other objects will appear hereafter.

The best modes in which it is contemplated applying the principles of the invention are shown in the accompanying drawings, but these are merely illustrative for it is intended that the patent shall cover by suitable expression in the appended claims whatever of patentable novelty exists in the invention disclosed.

In the drawings:

FIGURE 1 is a cross-sectioned side elevation view of a weir-less diaphragm valve embodying the present invention, the valve being shown with the diaphragm extended to the seating and with the backing cushion extended toward the diaphragm but not stretched;

FIGURE 2 is a view like FIG. 1 but showing the backing cushion stretched and squeezing the diaphragm against the seating to close the valve;

FIGURE 3 is a cross-sectioned end elevation view taken on line 3--3 of FIG. 2;

FIGURE 4 is a cross-sectioned end elevation view taken on line 4-4 of FIG. 5; and

FIGURE 5 is a view like FIG. 1 but showing the valve in open position.

Referring more particularly to the drawings the valve shown has a body 10 having a passageway 12 extending therethrough between the opposite end openings 14 and 16. These openings are provided with outstanding flanges 18 by which the valve body may be secured in a fluid handling piping system in the usual manner, for example by being bolted to corresponding pipe flanges. The passageway 12 is substantially straight and of substantially cylindrical cross-section throughout its length. However, midway between the ends of the passageway the body 10 is provided with a side opening 22 which is substantially circular and is surrounded by an annular flange 24 lying in a plane 26 parallel to the passageway 12. From the flange 24 the interior walls of the body converge inwardly and at the sides of the body merge substantially tangentially with the cylindrical walls of the passageway. The points of tangency are indicated by number 27 (see FIGS. 3 and 4).

The flange 24 surrounding the body opening 22 provides a clamping surface for the peripheral rim of a closure element combination which comprises a rubber or rubber-like resilient backing cushion member 28 and a relatively inert plastic diaphragm member 30 therefor. These members have registered peripheral portions 32 and 34, respectively, lying in planes parallel to and on one side of plane 26. They also have registered central bulged portions 36 and 38, respectively, extending to the other side of plane 26 so that the bulged central portion 38 of the plastic diaphragm member extends into and blocks the flow passageway 12. More specifically the peripheral portions 32 and 34 are clamped to the rim flange 24 by a corresponding flange 40 on the lower end and of a bonnet housing 42 which is secured to the body by means of nut and bolt assemblies 44, as shown. Tightening of the honnet flange 40 against the body flange 24 sealingly clamps the peripheral portions against the body flange 24 and thereby prevents fluid in the passageway 12 from escaping to the exterior of the valve and from entering the interior of the bonnet.

The resilient backing cushion member 28 and the inert plastic diaphragm member 30 each has the sloping sides of its bulged central portion thin enough to enable flexing of these sides into the configuration shown in FIGS. 4 and 5 when the compressor 46, to which the diaphragm combination is secured, is drawn open into the interior of the bonnet 42 by actuating mechanism 48 mounted thereon.

This withdrawal of the bulged central portions of the diaphragm combination out of the flow passageway 12 serves to open the valve, and conversely the operation of the actuating mechanism 48 to advance the compressor 46 towards the flow passageway 12 extends the central portions of the closure element combination first to the position of FIG. 1 and then by further advance of the compressor 46 to the position of FIGS. 2 and 3. In this latter position the bulged central portion of the plastic diaphragm member is pressed firmly against the body to close the valve.

FIG. 1 illustrates the shapes of the closure element combination members prior to any substantial deformation of them by the actuating mechanism 48. In other words the resilient backing cushion member 28 which conveniently may be formed of synthetic rubber is molded in the shape shown in FIG. 1. Similarly the inert plastic diaphragm member 30 which is also preferably a molded structure (for example, molded polytetrafluoroethylene) is preferably initially formed With shape illustrated in FIG. 1.

Thus, in accordance with this invention, although plastic diaphragm member 30 is molded in a shape which substantially matches the interior body wall surfaces, the re -51 of the compressor fits the interior surface of the resilient backing cushion member when the compressor has been advanced to stretch the resilient backing cushion member into firm contact with the interior of the plastic diaphragm member. Thus by operation of the actuating mechanism 48 (in this case turning of the hand wheel 52) the resilient backing cushion member is stretched until this member is in complete contact with the interior surface of the plastic diaphragm member. Thereafter further operation of the actuating mechanism causes the resilient backing cushion member 28 to squeeze the plastic diaphragm member tightly against the body walls.

In this manner the portions of the plastic diaphragm member which extended around the corner 54 formed by the sloping body walls and the body rim flange 24 are, by the stretching action of the resilient backing cushion member, pressed tightly against the body at this corner at the same time that the bulged central portion of the plastic diaphragm member is pressed into firm contact with the tapered body wall, and all of this is accomplished without stretching the plastic diaphragm member which actually forms the seal with the body.

In the embodiment of the invention shown in the drawings the plastic diaphragm member and the plastic backing cushion member are molded in the respective shapes shown in FIG. 1. In such case there is no distortion of any kind of the diaphragm or backing cushion in the positions of these members shown in FIG. 1.

It will be understood, however, that the diaphragm member and the backing cushion member could be molded in the respective shapes they assume in other valve positions and still be within the invention. Thus the flexing distortion of the bulges in these members must be distinguished from the stretching of these bulges. Even if both the diaphragm and backing cushion were molded with their bulges in a flexed position the flexing of these bulges to a position like FIG. 1 would involve a flexing not stretching. However, in accordance with this invention further advance of the compressor from its FIG. 1 position to close the valve would then involve stretching of the backing cushion member but would involve only further flexing of the diaphragm member.

Withdrawal of the plastic diaphragm member, and therefore of the resilient diaphragm member, is accomplished in this preferred construction by a lost-motion connection in which a stud 56 has its head 58 imbedded in the central thickened portion 60 of the plastic diaphragm member at the end of the bulge and has its shank 62 extending out of the interior surface of the plastic diaphragm member, along the axis 64 of the diaphragm and backing cushion member bulges, through an opening 66 in the resilient backing cushion member 28 and into a cavity 68 in the compressor. The stud shank 62 is threaded at its end and is by these threads secured to a nut 70 which lies loosely within the cavity 68 and which is free to move therein along the bulge axis. It is prevented from rotating, however, by a set screw 72 extending into the cavity to a point adjacent to a flat 74 on the nut 70, and the lower end 75 of the compressor through which the stud shank passes to reach the cavity limits the movement of the nut in that direction.

With this arrangement the plastic diaphragm member is not compelled to remain in intimate contact with the resilient backing cushion member. During the initial valve opening movements the plastic diaphragm member 30 is permitted to retain its molded shape if it tends to do so, but when the compressor 46 is withdrawn above the position shown in FIG. 1 the stud connection of the compressor to the plastic diaphragm member flexes the plastic diaphragm member, for example, eventually to the position shown in FIGS. 4 and 5.

With respect to the actuating mechanism 48, the compressor 46 is connected by a pin 76 to the lower end of a thread spindle 78 which is threadedly engaged in a rotatable bushing 80 journalled in an opening 82 in the upper end of the bonnet 42. The handwheel 52 is in turn connected to the portion of the bushing 80 which extends through the bonnet opening 82 and the rotation of the bushing is assured by a thrust bearing 84 between the interior bonnet surface 86 around the bonnet opening 82 and a flange 87 on the bushing.

Thus, when the handwheel 52 is rotated the bushing 80 is in turn rotated, and the threaded spindle (which is prevented from rotation by the sliding engagement of compressor arms 88 on vertical webbs 90 formed on the interior bonnet walls) moves up and down with respect to the bushing, handwheel and bonnet and thereby accomplishes the compressor movement required for the valve operation.

The connection between the spindle 78 and the compressor 46 is provided by a hub 92 which is formed on the compressor and which has a recess 94 communicating with the smaller cavity 68. A heavy disc 96 resting on the shoulder 98 formed by the difference in the diameters of the recess 94 and the cavity 68 is engaged by the lower end of the spindle when the valve is being closed. The pin 76 passing through the end of the spindle fits loosely in journal openings 100 on either side of the hub 92. This loose fit assures that the closing force exerted on the compressor by the spindle is exerted through the disc and not through the pin 76.

It is apparent that the stud 56 connecting the closure element combination to the compressor 46 must extend far enough below the compressor (when the nut 70' is at the bottom of the cavity 68) to accommodate the different lengths of the central bulged portions of the resilient backing cushion member and of the plastic diaphragm member. When the stud has this length the plastic diaphragm member is free to assume its molded shape if it is urged to do so by the forces acting on it, and at the same time the resilient backing cushion member is also free to assume its molded shape.

The compressor cavity 68 must extend upwardly far enough so that when the plastic diaphragm member engages the seating on the bottom of the body passageway the compressor is free to move downwardly with respect to the nut 70 until the resilient backing cushion member 28 is pressed firmly against the interior surface of the plastic diaphragm member 30.

As is illustrated in the drawings, the central bulged diaphragm portion is made up of three parts. The first part, 38a, extends from the clamped peripheral portion 34 and is substantially uniform in thickness. The second part, 3812, extends from the first part and increases in thickness, and the third part, 60, is substantially thicker than the other two and forms a bulge portion tip.

The reason for this novel configuration is to assure that the rolling flexing of the diaphragm will take place in the part 38a as shown in FIGS. 4 and 5.

The exterior surface of the bulged backing cushion portion is shaped to conform to the shape of the interior diaphragm surface when the backing cushion has been advanced by the compressor into engagement with the diaphragm to close the valve.

I claim:

1. A diaphragm valve comprising:

(1) a body having:

(A) a passageway therethrough,

(B) an opening on one side of said passageway,

(C) a flange around said opening,

(D) a diaphragm seating on the surface of said passageway,

(II) a flexible diaphragm having:

(A) a peripheral portion mounted on said flange,

(B) a central bulged portion which in one position of the valve:

(1) extends into said opening,

(2) engages said seating, (3) is substantially unstretched,

(III) a stretchable, fiexible resilient backing cushion member having:

(A) a peripheral portion mounted on said diaphragm peripheral portion, (B) a central bulged portion which in said one valve position:

(1) extends into said diaphragm bulged portion, (2) is spaced from said diaphragm central bulged portion, (3) is substantially unstretched,

(IV) means engaging said backing cushion bulged portion for moving said backing cushion bulged portion into engagement with said diaphragm central bulged portion and for squeezing said diaphragm and backing cushion central bulged portions between said means and said seating in the region of said passageway,

whereby said diaphragm is pressed against said seating in the region of said flange by stretching said backing cushion central bulged portion and is pressed against said seating in the region of said passageway by said squeezing.

2. A diaphragm valve according to claim 1 in which:

(I) said backing cushion engaging means comprises a compressor. 3. A diaphragm valve according to claim 1 in which: (I) said backing cushion engaging means comprises a compressor, I (II) said central bulged backing cushion portion has a concave side with an end wall,

(III) said compressor engages said end wall of said backing cushion concave side in said one valve position.

4. A diaphragm valve according to claim 1 in which:

(I) said backing cushion engaging means comprises a compressor,

(II) said diaphragm has embedded therein means for connecting said diaphragm to said compressor.

5. A diaphragm valve according to claim 4 in which said connecting means includes means for providing relative movement between said compressor and said diaphra'grn. I

6. A diaphragm valve according to claim 4 in which said connecting means comprises a stud having:

(I) one end embedded in said diaphragm,

(II) a central portion extending slidably through said backing cushion,

(HI) the other end secured to said compressor by a lost motion connection.

7. A diaphragm valve according to claim 1 in which:

(I) said diaphragm central bulged portion has:

(A) an internal surface, (B) a first sloping side wall part which:

(1) extends from said peripheral portion, (2) has a predetermined substantially uniform thickness, (C) a second sloping side wall part which:

(1) extends from said first part, (2) increases in thickness away from said first part, (D) a third end Wall part which:

( 1) forms a bulge portiontip, (2) is substantially thicker than said predetermined thickness,

(II) said backing cushion central bulged portion has an external surface which conforms to the said internal surface of said diaphragm central bulged portion when said backing cushion bulged portion is in said engagement with said diaphragm central bulged portion.

8. A diaphragm valve according to claim 1 in which said diaphragm seating extends from the flange on one side of said opening to the flange on the opposite side of said opening.

No references cited.

Claims (1)

1. A DIAPHRAGM VALVE COMPRISING: (I) A BODY HAVING: (A) A PASSAGEWAY THERETHROUGH, (B) AN OPENING ON ONE SIDE OF SAID PASSAGEWAY, (C) A FLANGE AROUND SAID OPENING, (D) A DIAPHRAGM SEATING ON THE SURFACE OF SAID PASSAGEWAY, (II) A FLEXIBLE DIAPHRAGM HAVING: (A) A PERIPHERAL PORTION MOUNTED ON SAID FLANGE, (B) A CENTRAL BULGED PORTION WHICH IN ONE POSITION OF THE VALVE: (1) EXTENDS INTO SAID OPENING, (2) ENGAGES SAID SEATING , (3) IS SUBSTANTIALLY UNSTRETCHED, (III) A STRETCHABLE, FLEXIBLE RESILIENT BACKING CUSHION MEMBER HAVING: (A) A PERIPHERAL PORTION MOUNTED ON SAID DIAPHRAGM PERIPHERAL PORTION, (B) A CENTRAL BULGED PORTION WHICH IN SAID ONE VALVE POSITION: (1) EXTENDS INTO SAID DIAPHRAGM BULGED PORTION, (2) IS SPACED FROM SAID DIAPHRAGM CENTRAL BULGED PORTION, (3) IS SUBSTANTIALLY UNSTRETCHED, (IV) MEANS ENGAGING SAID BACKING CUSHION BULGED PORTION FOR MOVING SAID BACKING CUSHION BULGED PORTION INTO ENGAGEMENT WITH SAID DIAPHRAGM CENTRAL BULGED PORTION AND FOR SQUEEZING SAID DIAPHRAGM AND BACKING CUSHION CENTRAL BULGED PORTIONS BETWEEN SAID MEANS AND SAID SEATING IN THE REGION OF SAID PASSAGEWAY, WHEREBY SAID DIAPHRAGM IS PRESSED AGAINST SAID SEATING IN THE REGION OF SAID FLANGE BY STRETCHING SAID BACKING CUSHION CENTRAL BULGED PORTION AND IS PRESSED AGAINST SAID SEATING IN THE REGION OF SAID PASSAGEWAY BY SAID SQUEEZING.

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