US3926211A

US3926211A - Fluid flow control valve

Info

Publication number: US3926211A
Application number: US467100A
Authority: US
Inventors: Bernard Graham Maclarty
Original assignee: Phoenix Valve Manufacturers Ltd
Current assignee: Phoenix Valve Manufacturers Ltd; Zimco Industries Pty Ltd
Priority date: 1973-05-08
Filing date: 1974-05-06
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: DE2421600A1; ES426059A1; BR7403698D0; CA999210A; IL44764A; FR2229002B1; IT1012185B; IL44764A0; GB1463873A; ZA733118B; CH586363A5; JPS5031431A; FR2229002A1; AU6868974A

Abstract

A fluid flow control valve is disclosed in which the movable element of the valve is in the form of a spool mounted in a casing by means of two rolling diaphragms. The spool is hollow and a fixed cross-bar passes through it. In one form, the spool carries a valve closure member and the outlet is in the centre of the cross-bar. In another form, the cross-bar carries the closure member and the valve outlet is an axial bore leading from the hollow interior of the spool. The valve inlet leads to the annular chamber defined between the casing, the spool and the diaphragms. The areas of the end walls of the annular chamber are different to one another and are chosen so that an inlet pressure derived force acts on the spool to reduce the out of balance forces which act thereon due to the provision of the outlet. A modification which acts as a flushing valve is also disclosed.

Description

llnited States Patent 119 MacLarty Dec. 16, 1975 FLUID FLOW CONTROL VALVE 2,861,587 11/1958 Hursen 137/494 Inventor: Bernard Graham MacLarty 3,270,757 9/1966 Engler l37/505.38 X

Bedfordvlew South Afnca Primary ExaminerMartin P. Schwadron [73] Assignee: Phoenix Valve Manufacturers Assistant Examiner-Robert J Miller Limited, Durban, South Africa 22 Filed: May 6, 1974 [57] ABSTRACT A fluid flow control valve is disclosed in which the [21] Appl. No. 467,100 movable element of the valve is in the form of a spool mounted in a casing by means of two rolling dia- [30] Foreign Application Priority Data phragms. The spool is hollow and a fixed cross-bar May 8,1973 South Africa 73/3118 Passes through one form, the Spool Carries a valve closure member and the outlet is in the centre of 52 s CL 137 94; 75 13750525 the cross-bar. In another form, the crossbar carries 51 int. 01 F16K 31/365; F16K 31/385 the Closure member and the valve Outlet is an axial 5 Field f Search 137/494 497, 4842, 4846 bore leading from the hollow interior of the spool. The

137/4844, 5 5 5 501, 50518 valve inlet leads to the annular chamber defined be- 505 505 5 5 5 5 5 50525 tween the casing, the spool and the diaphragms. The 488 492 4925, 505 251, 282, 496 areas of the end walls of the annular chamber are different to one another and are chosen so that an inlet 5 References Cited pressure derived force acts on the spool to reduce the UNITED STATES PATENTS out of balance forces which act thereon due to the 815 917 3/1906 d 137/505 18 provision of the outlet. A modification which acts as a y 973,609 /1910 Abrams 1 137/505.25 flushing valve also dlsclosed. 1,978,398 10/1934 Becker 1. l37/505.25 10 Claims, 5 Drawing Figures 76 0 I6 6 g l0 0 A 44 46 o 34 do Z5 50 II 64 a 1 L U.S. Patent De c.16,1975 Sheet2of4 3,926,211

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U.S. Patent Dec. 16, 1975 Sheet 3 of4 3,926,211

F/CJ

US. Patent Dec. 16,1975 Sheet 401-4 3,926,211

FICA

FLUID FLOW CONTROL VALVE This invention relates to fluid flow control valves.

According to one aspect of the present invention there is provided a fluid flow control valve comprising a casing and a movable valve element in the casing, in which valve the inlet of the valve leads to a chamber bounded externally by said casing and internally by said element, that wall which forms one end of said chamber having an area different to that of the wall which fonns the other end of the chamber, and an outlet from the valve, the difference in area between said end walls being a function of the area of said outlet, and both walls being movable relatively to the casing.

According to a further aspect of the present invention there is provided a fluid flow control valve comprising a casing, an inlet leading into said casing, a movable valve element in said casing, first and second means sealing between said element and said casing, such means being spaced apart in the direction in which said element is capable of movement and, to gether with said casing and said element, bounding a pressure chamber into which said inlet leads, the valve element having a hollow interior which communicates with said chamber and there being a valve outlet lead ing from said hollow interior, said element having a position in which said outlet is closed and being capable of movement from said position to open the valve, and the area of one end wall of said chamber, over which area the pressure in said chamber is effective, being different to the area of the other end wall of said chamber, over which the pressure in said chamber is effective, and the difference being such as to provide on said element a force tending to reduce the out of balance effect arising from the provision of said outlet.

Embodiments of the invention will now be described, by way of the example, with reference to the accompanying drawings, in which:

FIG. -l is a vertical section through a pressure reducing valve according to one embodiment of the invention;

FIG. 2 is a vertical section through a pressure reducing valve according to another embodiment of the invention;

FIG. 3 is a vertical section of the valve of FIG. 1 modified for use as a flushing valve;

FIG. 4 is a section on line IVIV of FIG. 1; and FIG. 5 is a section on line VV of FIG. 3.

Referring firstly to FIGS. 1 and 4, reference numeral generally indicates a pressure reducing valve comprising a casing 12 which includes a main part 14 and upper and

lower end caps

16 and 18. An inlet structure 20 includes a non-retum ball valve 22, a union 24, and an elbow 26 provided with a filter screen 28. The free end of the elbow 26 is provided with an inlet connection 30. The structure 20 will be described in more detail subsequently.

The valve 10 further includes a movable valve element 32 which is supported by a pair of

rolling diaphragms

34 and 36. The element 32 is shown in simplified form in FIG. 3.

The

diaphragms

34 and 36 seal between the element 32 and the casing 12 and are spaced apart in the direction in which the element 32 is capable of moving. Together with the casing 12 and element 32, the diaphragms bound a generally annular pressure chamber 38 into which the inlet 40 formed in the casing 12 2 leads. The element 32 bounds the chamber 38 internally and the casing 12 bounds the chamber 38 externally.

The valve element 32 comprises a main part 42 formed with two diametrically opposed slots 44. The upper end 46 of the part 42 is closed and over this end is fitted a retaining ring 48 for the inner periphery of the diaphragm 34 and an internally threaded locking ring 50 for urging the ring 48 into clamping engagement with the diaphragm 34. The rings 48 and 50 can be integral in which case the ring 50 is not threaded but simply fits over the end 46 and secured by swaging.

At its lower end, the main part 42 is formed with an externally threaded spigot 52 above which there is a rib 54, the slots 44 dividing the spigot and rib into two arcuate portions. A sealing ring 56 is clamped between the rib 54 and a seat element 58 which is screwed onto the spigot 52. The lower end of the element 58 is externally threaded and a retaining ring 60 for the inner periphery of the diaphragm 36 is fitted over the threaded portion of the element 58. An internally threaded locking ring 62 is threaded onto the element 58 and urges the ring 60 against the diaphragm 36. If the rings 60 and 62 are integral, they would be secured by swaging and not by threading.

A cross-member 64 extends across the casing 12 and passes through the slots 44. The member 64 is formed with a core 66 which is within the element 32 and within which is mounted a valve closure member 68. The member 68 co-operates with a seat 70 which encircles the upper end of the valve outlet constituted by a bore 72 in the element 58.

The outlet union of the valve is shown at 74 and a spring 76 acts between the end cap 16 and the end 46. The chamber bounded by the end cap 16 can be closed so that air trapped therein acts as a cushion for the element 32.

The diameter (D1) of the end cap 16 is less than the diameter (D2) of the end cap 18. The end portions of the element 32 are also of different diameters. Thus the ring 48 is of smaller diameter than the ring 60, these two rings determining the effective diameter of the end walls of the chamber 38 as will be discussed in more detail below.

Turning now to the structure 20, this comprises an externally threaded inlet portion 78 having a bellshaped bore within which there are ribs 80. These ribs prevent the ball 22 from closing-off flow of water into the valve through the structure 20.

The elbow 26 includes an external flange 82 over which a locking ring 84, forming part of the union 24, is slipped and threaded onto the portion 78 to hold the elbow in place. An O-ring seals between the portion 78 and flange 82. A seat element 86 for the ball 22 is located between an internal shoulder of the portion 78 and the holding ring 88 of the filter screen 28 which ring is itself against a shoulder of the elbow 26. The element 86 has a central aperture which the ball 22 enters should water tend to flow from the valve 10 to the elbow 26.

The inlet connection 30 comprises a locking ring 90 threaded onto the free end of the elbow 26 and an in ternally threaded spigot 92 held against the elbow 26 by the ring 90.

If desired, an airtight inlet (not shown) may be provided so that the chamber within the cap 16 may be opened and a liquid, such as water, may be introduced into the chamber whereby the volume of the chamber is reduced. The gas in the reduced volume chamber serves to bias and cushion the element 32 without the use of the spring 76 but can act in conjunction with the spring.

When the valve is closed, that is, the member 68 is in engagement with the seat 70, water at inlet pressure is confined within the annular pressure chamber 38 with which the hollow interior of the element 32 communicates. Within said hollow interior, certain surfaces are subjected to inlet pressure and the resultant forces act in opposition to one another in tending to move the element 32 towards and away from the closure member 68. By virtue of the provision of the outlet bore 72, the area on which inlet pressure acts to create a valve opening force is less than the area on which fluid pressure acts to create a valve closing force. The

diaphragms

34 and 36 are subjected to pressure subsisting in the chamber 38 (which is inlet pressure and hence forces are created which act in opposite directions on the element 32. It will be understood that, by virtue of the difference in diameters D1 and D2 and the differ ence in diameter of the rings 48 and 60, the effective area of the end wall constituted by the diaphragm 36 is greater than the effective area of the end wall constituted by diaphragm 34.

In use of the valve, back pressure at the outlet acts on the element 32 and displaces it, against the action of the spring 76, to the position in which the valve is closed. When the pressure drops at the outlet, for example, because a tap downstream of the hot water geyser to which the valve is connected has been opened, the force exerted by the spring 76 exceeds that exerted by the back pressure. The element 32 thus moves (downwardly as viewed in FIG. 1) so that the seat element 72 moves away from the member 68; Upon the tap being closed, back pressure is recreated and the valve closes. The force exerted by the spring 76 is the main factor in determining the back pressure which must be attained before the valve closes.

The inlet pressure to which a valve connected to the mains supply is subjected varies widely during the day as the demand for water rises and falls. By appropriate selection of the relative magnitudes of those areas which are subjected to inlet pressure, it is possible to influence the back pressure required to close the valve.

If the difference in area between the walls constituted by the diaphragms exactly equals the area of the outlet bore 72, then all inlet pressure derived forces on the element 32 are balanced and the pressure at which the valve closes is independent of inlet pressure.

If the difference in areas is slightly greater than the area of the bore 72 then, with increasing inlet pressure, there is an increasing force tending to open the valve. In these circumstances, the back pressure required to close the valve rises with inlet pressure. Conversely, where the difference in areas is slightly less than the area of the bore 72 then, with increasing inlet pressure, there is an increasing inlet pressure derived force tending to close the valve. Thus, under these conditions, the back pressure required to close the valve steadily decreases with increasing inlet pressure.

The amount by which said difference in areas can itself differ from the area of the bore 72 depends to some extent on the fluctuations which can be expected in inlet pressure, to some extent on the size of the spring 76 which can be used, and further on the magnitude of the pressure for which the valve is designed. If great variations in inlet pressure or high inlet pressures, are

4 to be expected, then only a small percentage difference, say, up to 2/2% above or below parity between the difference in areas and the area of the outlet 72 can be accommodated. If, on the other hand, only small inlet pressure variations and low inlet pressures are expected, this percentage can be increased to, say, 5%.

Referring now to FIG. 2, reference numeral generally indicates a pressure reducing valve according to another embodiment of the invention. For ease of reference, identical parts of the valves 10 and 100 are denoted by like. reference numerals.

The valve 100 is similar to the valve 10 except that the valve closure member 68 is now carried by the element 32 and the outlet bore 72 is provided in the crossmember 64.

The outlet bore 72 communicates with a transverse passage 102 which leads through the wall of the main casing part 14. A chamber 104 is defined between the cap 18 and the element 32 and a conduit leads from the passage 102 to the chamber 104.

The element 32 of this valve is of somewhat simpler construction than that described above and includes a main part 106, in which diametrically opposed slots for receiving the member 64 are provided, and two

end caps

108 and 110. The diaphragm 34 is clamped between the part 106 and cap 108, and similarly the dia phragm36 is clamped between the cap 110 and the part 106. The closure member 68 forms part of the cap 110 which is castellated at 1 12 to prevent the chamber 104 being cut-off from the passage 102 when the valve is fully open (as shown).

This valve operates in the same manner as valve 10.

Turning now to FIGS. 3 and 5, this valve is a modification of the valve of FIG. 1 and where applicable like parts have been correspondingly referenced. In this valve, the cross member 64 is at right angles to the inlet 40 and the outlet union 74 is at the upper end of the casing 12 instead of at the lower end. Hence the cap 18 becomes an upper cap and the cap 16 a lower cap which, together with the element, bounds a chamber 114. The chamber 114 is connected by a passage 1 16 to the inlet passage upsteam of the inlet 40 and there is a manually operable e.g. push button, valve 118 in the passage 116.

An outlet passage 120 having a flow regulating needle 122 therein leads from the chamber 1 14 to an outlet chamber 124. A spring 126 urges the element to the position in which the valve is closed.

The element 32 is diagrammatically shown and comprises a main part 128, closure cap 130 and end rings 132. The upper ring 132 is castellated at 134 to ensure that in the fully open position shown the passage 120 is not cut-off from the chamber 124. In the same way as in the abovedescribed embodiments, the part 128 is formed with slots (running front to rear in the drawing) which place the hollow interior of the element 32 in communication with the pressure chamber which encircles the element 32 and into which the inlet 40 opens.

In use, when there is no pressure in the chamber 124 or in the chamber 114, the spring 126 holds the valve in the closed condition. For the reasons explained in detail with reference to FIG. 1, inlet pressure does not exert any resultant force on the element 32, or if there is a resultant force the magnitude of this is closely controlled. When the valve 118 is opened, the pressure in the chamber l14 increases and a pressure derived force is exerted on the element 32. This force overcomes the force exerted by the spring 126 and the element 32 moves to open the valve. Once the valve 118 closes, the pressure in the chamber 114 begins to decrease as leakage occurs through the passage 120. Eventually the force exerted by the spring overcomes the force exerted by the water under pressure in the chamber 114 and the valve closes. The rate of flow along the passage 120, and hence the time that the valve takes to close, depends on the setting of the needle 122.

If desired, the spring 126 can be omitted and the difference in areas of the ends of the chamber 38 with respect to the area of the bore 72 so chosen that there is on the element 32 an inlet pressure derived force urging the element in the closing direction i.e. against the force exerted by the pressure in the chamber 114.

The connection between the hollow interior of the valve element 32 (and which is in communication with the outlet chamber 124 via the bore 124.1 and the inlet 40) is best seen in FIG. 5. It will be noted from this that communication is via the part-cylindrical gap between the

parts

14 and 128 and the slots 44.

I claim:

1. A fluid flow control valve comprising a casing, an inlet leading into said casing, a movable valve element in said casing, first and second means sealing between said element and said casing, such means being spaced apart in the direction in which said element is capable of movement and, together with said casing and said element, bounding a pressure chamber into which said inlet leads, the valve element having a hollow interior and there being an outlet from said hollow interior of the valve element which outlet reduces the area of the movable element on which inlet pressure acts in one direction and which opens into an outlet path leading to the exterior of the valve, said pressure chamber communicating with said outlet path by way of said outlet and said hollow interior, a valve closure member for closing-off said outlet, and said element having a position in which said member closes said outlet to prevent flow from said hollow interior to said outlet path and being capable of movement from said position to establish communication between said hollow interior and said outlet path thereby to open the valve, and the area of one end wall of said chamber, over which area inlet pressure is effective, being different to the area of the other end wall of said chamber over which inlet pressure is effective, and the difference providing a differential area subjected to inlet pressure which compensates for the reduction in inlet pressure subjected area arising from the provision of said outlet.

2. A valve according to claim 1, in which each of said first and second means is constituted by a diaphragm having its inner periphery secured to said element and its outer periphery to said casing.

3. A valve according to claim 1, in which said outlet is constituted by a bore formed in said element and extending from said hollow interior in the direction in which the element is capable of movement.

4. A valve according to claim 3, in which said element includes diametrically opposed slots and a fixed cross-member extends through the element by way of the slots, there being a valve closure member carried by said cross-member and cooperating with said outlet.

5. A valve according to claim 1, in which said element includes diametrically opposed slots and a fixed cross-member extends through the element by way of the slots, said outlet being constituted by a passage in said cross-member and there being a valve closure member carried by said element for closing-off communication between said passage and said hollow interior.

6. A valve according to claim 1, in which said outlet has an area such that said difference in areas equals said area of said outlet so that said element is unaffected by variations in inlet pressure.

7. A valve according to claim 1, in which said outlet has an area such that said difference in areas is more or less than said area of said outlet whereby a force de rived from inlet pressure is exerted on said element which force varies with inlet pressure.

8. A valve according to claim 1, in which one face of said element is in communication with said outlet so that the element is subjected to back pressure at said outlet and a further face of said element is subjected to a force opposing the force exerted thereon by the back pressure.

9. A valve according to claim 8, and including a coil spring for exerting the opposing force.

10. A valve according to claim 1, and comprising spring means for exerting on said element a force tending to move it to the closed position, and a chamber the pressure in which exerts a force tending to move the element to the open position, an inlet to said chamber, a valve for temporarily connecting this chamber to a source of pressure fluid, and a bleed passage from said chamber so that the pressure therein drops over a period of time.

Claims

4. A valve according to claim 3, in which said element includes diametrically opposed slots and a fixed cross-member extends through the element by way of the slots, there being a valve closure member carried by said cross-member and co-operating with said outlet.

7. A valve according to claim 1, in which said outlet has an area such that said difference in areas is more or less than said area of said outlet whereby a force derived from inlet pressure is exerted on said element which force varies with inlet pressure.