CA1212886A - Anti-cavitation valve assembly - Google Patents
Anti-cavitation valve assemblyInfo
- Publication number
- CA1212886A CA1212886A CA000486370A CA486370A CA1212886A CA 1212886 A CA1212886 A CA 1212886A CA 000486370 A CA000486370 A CA 000486370A CA 486370 A CA486370 A CA 486370A CA 1212886 A CA1212886 A CA 1212886A
- Authority
- CA
- Canada
- Prior art keywords
- valve member
- valve
- liquid
- flow
- outlet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007788 liquid Substances 0.000 claims abstract description 54
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 230000002250 progressing effect Effects 0.000 claims 1
- 238000007789 sealing Methods 0.000 claims 1
- 150000002500 ions Chemical class 0.000 description 6
- 230000002093 peripheral effect Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- JOFWLTCLBGQGBO-UHFFFAOYSA-N triazolam Chemical compound C12=CC(Cl)=CC=C2N2C(C)=NN=C2CN=C1C1=CC=CC=C1Cl JOFWLTCLBGQGBO-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/12—Actuating devices; Operating means; Releasing devices actuated by fluid
- F16K31/36—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor
- F16K31/40—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor
- F16K31/406—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor acting on a piston
- F16K31/408—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor acting on a piston the discharge being effected through the piston and being blockable by an electrically-actuated member making contact with the piston
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K25/00—Details relating to contact between valve members and seats
- F16K25/04—Arrangements for preventing erosion, not otherwise provided for
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Details Of Valves (AREA)
- Lift Valve (AREA)
Abstract
ANTI-CAVITATION VALVE ASSEMBLY
Abstract of Disclosure The valve assembly for the control of flow of liquid from a source of liquid at high pressure to a place of use has at least one restrictive orifice adjacent a movable valve member and valve seat to provide pressure drops in series in the liquid each of which pressure drops is of a magnitude sufficient to maintain the liquid pressure above the vapor pressure of the liquidity the inlet of the valve assembly so that cavitation does not occur. The restrictive orifice varying in flow area automatically in direct proportion to the variable flow area between said movable valve member and the valve seat.
Abstract of Disclosure The valve assembly for the control of flow of liquid from a source of liquid at high pressure to a place of use has at least one restrictive orifice adjacent a movable valve member and valve seat to provide pressure drops in series in the liquid each of which pressure drops is of a magnitude sufficient to maintain the liquid pressure above the vapor pressure of the liquidity the inlet of the valve assembly so that cavitation does not occur. The restrictive orifice varying in flow area automatically in direct proportion to the variable flow area between said movable valve member and the valve seat.
Description
8E~
This invention relates to valves for controlling liquid flow and, more particularly, to a valve assembly having anti-cavitation means.
In heretofore known valves, such as pilot operated, modulating solenoid valves, a phenomenon called cavitation can occur where the valve is utilized to control flow of non-degassed liquids. Cavitation is produced when a liquid has flashed to form local cavities or bubbles which there-after collapse. Flashing occurs when the pressure of the liquid falls below the vapor pressure, and bubble collapse occurs when the pressure of the liquid returns to a value above its vapox pressure. This process of cavitation causes erosion, noise and impedes liquid flow, as well as producing a drop in efficiency of fluid machinery. It has been found in valve assemblies that the rapid pressure drop across the open valve is at times of such a magnitude that the liquid pressure drops below the vapor pressure and hence results in cavitation. A cavitation condition is of particular concern in pilot operated, modulating valves which operate to temperatures of 1000F and pressures of 10,000 psi or greater and have frequent valve open and close cyclic operation. The difficulty of obviating cavitation in pilot operated, modulating valves is that the construction of such valves limits movements to relatively small distances as compared with on-off valves of conventional desi~nO This undesirable cavitation phenomenon is substantially minimized in the valve assembly according to this invention.
It is, therefore, an object oE the present invention to provide a valve assembly for the control of liquid flow wherein cavitation is substantially minimized. It is another object of this invention to provide a valve assembly Eor the
This invention relates to valves for controlling liquid flow and, more particularly, to a valve assembly having anti-cavitation means.
In heretofore known valves, such as pilot operated, modulating solenoid valves, a phenomenon called cavitation can occur where the valve is utilized to control flow of non-degassed liquids. Cavitation is produced when a liquid has flashed to form local cavities or bubbles which there-after collapse. Flashing occurs when the pressure of the liquid falls below the vapor pressure, and bubble collapse occurs when the pressure of the liquid returns to a value above its vapox pressure. This process of cavitation causes erosion, noise and impedes liquid flow, as well as producing a drop in efficiency of fluid machinery. It has been found in valve assemblies that the rapid pressure drop across the open valve is at times of such a magnitude that the liquid pressure drops below the vapor pressure and hence results in cavitation. A cavitation condition is of particular concern in pilot operated, modulating valves which operate to temperatures of 1000F and pressures of 10,000 psi or greater and have frequent valve open and close cyclic operation. The difficulty of obviating cavitation in pilot operated, modulating valves is that the construction of such valves limits movements to relatively small distances as compared with on-off valves of conventional desi~nO This undesirable cavitation phenomenon is substantially minimized in the valve assembly according to this invention.
It is, therefore, an object oE the present invention to provide a valve assembly for the control of liquid flow wherein cavitation is substantially minimized. It is another object of this invention to provide a valve assembly Eor the
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control of liquid flow which is less subject to erosion and quieter in operation than heretofore known liquid flow control valves. It is a further object of this invention to provide liquid flow control valve assembly which provides relatively free flow of liquid'therethrough.
In view of the foregoing, the present invention contemplates a novel valve assembly for controlling the flow of liqùid'which in its broadest aspect comprises a body portion having a liquid inlet communicating with a source of liquid' and a liquid outlet for passing liquid'from the valve assembly and at least one valve seat disposed between said inlet and said outlet. A movable valve member is disposed in the body portion for reciprocative movement between a position again'st said'valve seat to prevent flow of li~uid'from said inlet to said'outlet and a fully open position away from said valve seat to allow flow of liquid from the inlet to the outlet. A port means is located between said in'let and the valve seat which coacts with the movable valve member to provide a variable restriction to liquid'flow which is directly proportional to the variable flow area between said movable valve member and the valve seat.
In a narrower aspect of this'invention, the port means includes a stationary sleeve within'which the movable valve member is'disposed for reciprocative movement toward and away from said valve seat and which sleeve has a plurality of circum-ferentially spaced first openings, the flow areas of which varyin'size with the posit'ions of the movable valve member away from the valve seat. The port means further includes a bore in'the body portion spaced downstream of the valve seat and an extension of the movable valve member which projects beyond the valve seat into said'bore and for slidable movement relative thereto. The extension of the movable valve is constructed so that at least one second opening is defined between the end of the bore and the extension, and which second openin~ varies in size in direct proportlon to the distances of the movable valve member away from the valve seat. The first and second openings provide, in co-operation with the coaction of the movable valve member and valve seat, a series of pressure drops of relatively small magnitude to prevent, at each point, the liquid pressure falling below the vapor pressure of the liquid at the inlet of the valve body, thus, substantially min'imizing the possibilïty of producing the phenomenon known as cavitatioh.
A feature of the present invention is'that the movable valve member is a disc which is'slid`able in~a stationary sleeve and has a first and second reduced diameter portions, the first reduced diameter portion being adapted to seat or engage the valve seat, while the second reduced diameter portioh has a diametral notch in'the end thereof to form, with the end of the bore in'which it'is'slidably disposed, variable orifices or openings for the last in'the series of pressure drops of the liquid'in'flowing from the inlet to the outlet.
In a second embodiment of this inventioh, the stationary sleeve is'dimensioned so that it is`spaced from the fir'st reduced diameter portioh of the disc to form an annular space in'which a helical spring is disposed, the spacing between 25' the coils forming a plurality of restricted orif'ices or openings.
The spring is'connected to the disc so that, as the disc moves, the space between the spring coils vary in'size. Thus, the plurality of parallel openings vary in'flow area in'direct proportion to the change in the distance of the first reduced diameter portion of the disc from a seated posit'ion against the valve seat.
~2~
The invention will be more fully understood from the following detailed description thereof which considered in connection with the accompanying drawings wherein two embodiments of the invention are illustrated by way of example and in which:
Fig. 1 is a view in'cross section of a valve assembly according to a first embodiment of this invention for the control of liquid flow;
Fig. 2 is an enlarged fragmentary portion of a portion of the valve assembly shown in Fig'. l; and 0 Fig. 3 is an enlarged fragmentary portion of the valve assembly, similar to Fig. 2, showing a second embodiment of the present invention.
Now, referring to the drawings and more particularly to Figs. l and 2, the reference number 10 generally designates the valve assembly according to a first embodiment of this invention. It is'to be understood, while the valve assembly 10 is shown and will be described as a pilot operated, modulating, solenoid liquid'flow control valve assembly, the invention is not necessarily limited thereto. While the invention is'particuIarly desirable for pilot operated moduIating types of valves, it is' not limited thereto~ Therefore, the invention is shown and described in a pilot operated, moduIating, solenoid'liquid flow control valve assembly only for illustration purposes; that the invention has application to many types of liquid'flow control valves, particularly those that operate under high liquid temperatures and pressures and where valve movements are restricted to very small dis'tances, without departure from the scope and spirit'of this'invention.
The valve assembly 10 shown in'Figs. 1 and ~ briefly comprises a valve body 12 having a liquid'passageway 1~ which p~
has at one end an inlet port 16 and at the opposite end an outlet port 18. A main valve seat 20 is formed in passageway 14 between inlet and outlet ports 16 and 18. The portion oE
passageway 14 upstream from valve seat 20 will be identified as inlet passageway 14a, while the downstream portion of passageway 14 will be referred to as outlet passageway 14b.
A main movable valve member 22 (sometimes referred herein as a "main'disc") is mounted for reciprocative movement within' valve body 12 to posit'ions where the movable valve member is' abutting valve seat 20 and hence prevents flow of liquid through passageway 14 and a fully open posit'ion where the movable valve member is spaced away from valve seat 20 a miximum dis'tance.
Since valve assembly 10 is a pilot operated, modulating type valve, a pilot valve 24 is'mounted for reciprocative movement within'a bore in main valve member 22. In addition, the valve assembly 10 has an electromagnetic'assembly or solenoid motor 26 for controlling the operation of the pilot valve 24 and hence main valve member 22. The electromagnetic'assembly 26 is supported on a bonnet assembly 28 which is'conneGted and forms part of valve body 12. The bonnet assembly 2a generally comprises an elongated, non-magnetic', tubu-lar member 30 posi-tioned at an open end 32 within'a generally cylindric'al portion 34 of valve body 12, which portion 34 extends~angularly with respect to a valve portion 36 through which extends passageway 14. The tubular member 30 is'mounted in'valve portion 34 in spaced relation to valve seat 20 and coaxial therewith.
In operation of valve assembly 10, liquid'in'passage-way 14 supplied thereto through inlet port 16 from~a source of supply (not shown), enters the valve through bleed passageways 25 and 26 so that inlet pressure acts on all surfaces of piIot valve 24 and main dlsc 22, thus permitting spring 42 and return spring 44 to urge or bias pilot valve 24 and Inain movable valve member 22, respectively, in a seated or closed position, as shown. When it is'desired to open main movable valve member 22, the solenoid 26 is energized by a suitable source of electrical power (not shown). The magnetic flux lines thus generated upon energization cause pilot armature 38 to axially move again'st the force of a return spring 44.
This axial movement of pilot armature 38 against the bia'sing force of spring 44, also unseats pilot valve 24 without acting on the main'movable valve member 22 because of the lost motion provided between pin 48 and its associated slot 46 and pin 49 and its associa'ted slot 50 in~armature 38~ Continued energ-iz'ation and axial movement unseats main'movable valve member 22 to the full open position, assisted by the pressure dif'ferential across main'valve member 22. This'pressure differential across main valve member 22 is'caused by the opening or unseating of pilot valve 2'4 which communicates the interior of the valve with the outlet p~rt 18 and -thus effects a reduction in liquid pressure-acting a~ain'st the main'valve member surfaces in'a direction toward valve seat 20. Therefore, with inlet liquid'pressure still acting again'st the surface 52 via'bleed passageway 25 in'a stationary sleeve 56, and the pressure on the opposite surfaces of main'valve member 2~
reduced, a resuItant force is exerted on main valve member 22 in a direction to unseat the latter. Once liquid'pressure equilibrium across main'valve member 22 is'reached, any change in liquid inlet or outlet pressure will change the differential pressure across the main valve member and cause it's movement in response to such pressure dif'~erential. The large sudden pressure drop o~ the liquid as it flows past valve seat 20 into outlet passagway 14b and the resultant cavitation is avoided in valve assembly 10 in accordance with the present invention as hereinafter fully described.
As bes~ shown in Figure 2, valve assembly 10, main valve member 22 has a cylindrical portion 58, a first reduced diameter portion 60 and second reduced diameter portion 62 which has an end shaped and dimensioned to seat against valve seat 20. The main movable valve member 22 also has a third reduced diameter portion 64 and an enlarged diameter end portion or extension 66. The stationary sleeve 56, which is disposed between open end 32 of tubular member 30 and the valve seat 20, is so formed and dimensioned that the peripheral surfaces o~ portions 58 and 60 of main valve member 22 slidably engage the interior surface of sleeve 56. The valve seat 20 is formed along the inner edge of a ring element 68 which is suitably secured in housing or body portion 12 of valve assembly 10.
The interior surface of ring element 68 has a counterbored 2~ portion 70 which forms an enlarged diameter, inner annular surface and a reduced diameter, inner annular surface 74.
The inner annular surface 74 slidably engages the outer peripheral surface of enlarged diameter portion 66 of main disc 22. The second and third reduced diameter portions 6 and 64, enlarged portion 66 and annular surface of counter-bored portion 70 define an annular secondary inlet chamber 76. The end of enlarged portion 66 of main disc 22 has a diametral notch or groove 78 therein. This groove 78 co~
acts with upper peripheral edge portion 80 of inner annular surface 74 to define variable flow area orifices or outlets communicating annular inlet chamber 76 with outlet passage-way 14b.
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The stationar~ sleeve 56 has a reduced diameter end portion ~2, the inner surface of which slidably engages first reduced diameter portion 60 of main valve member 22.
The interstices between the main disc portion 60 and the inner surface of sleeve 56 is sealed by an O-ring seal 81 while the interstices between the adjacent surfaces of portion 58 of main disc 22 and sleeve 56 are sealed by an O-ring 83. ~ plurality of circumferentially spaced ports 84 are provided in reduced diameter end portion 82. These ports 34 coact with the end edge 86 of first reduced diameter end portion 60 of main disc 22 to provide variable flow area orifices or outlets communicating inlet passage-way 14a with the annulus 88 formed by the reduced diameter end portion 82 of sleeve 56, the end of ring element 6~, and reduced diameter portions 60 and 62 of main disc 22.
In operation, the orifices defined by ports 84 and end edge 86 of main valve member 22 function as first stage variable flow area restrictions upstream of valve seat 20.
The orifices defined by groove 78 and edge portion 80 form second stage variable flow area restricl:ions downstream of valve seat 20. The first and second stage variable flow area restrictions are so sized in relation to the total predetermined pressure drop of the liquid from inlet passageway l~a to outlet passageway 14b that at each stage and at valve seat 20 a pressure drop is achieved without the liquid falling below its vapor pressure and hence avoids the phenomenon known as cavitation. The total flow area at the first and second stages varies in direct proportional ~elationship to the movement of main valve member 22 toward and away from seat 20. Thus, valve assembly 10 automatically effects the avoidance of cavitation as changes _g _ :~,J :
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in the pressure differential between the liquid in inlet passageway 14a and in outlet passageway 14b occur and cause modulation of main'valve member 22.
In Fig. 3 a portion of a valve assembly 90 is shown, which assembly constitutes~a second embodiment of this'inven-tion. Valve assembly 90 essentially differs from valve assembly 10 in that the fir'st stage variable flow area restrictions are defined by a helic'ally wound spring 92 in'stead of the coaction between first reduced diameter portion 60 of the main'valve member 22 and ports 84 in'stationary sleeve 56 as has been disclosed for valve assembly 10.
Accordingly, parts of valve assembly 90, similar to parts of valve assembly 10, will be identif'ied by the same reference number with the suffix A added thereto.
As shown in Fig'. 3, the stationary sleeve 56A does not have a reduced diameter portion 82 as does stationary sleeve-56, but is'of substantia'lly uniform diameter to form an annulus 94 between its inner surface and the outer peripheral surface of first reduced diameter portion 60A. In annulus 94 is disposed helical sprin~ 92 which is'preferably formed from wire of rectangular cross-section. The spring is'so dimensioned and assembled that as main'valve member or main'disc 22 moves between it's fully open and closed posit'ions, the space 96 between next adjacent coil's increase and decrease in'direct proportion to the movement of main'valve member 22A~ The spaces 96 form variable flow area restriction orif'ices which function to con~unicate inlet passageway 14aA, via'ports 84A, with space, in annulus 9~, formed~between the inner surface of the coils of spring 92 and outer surface of first reduced portion 60A of main'disc 22A and annulus 88A.
The valve assembly 90 is operationally the same as valve assembly 10 in that it provides for a controlled, sequential pressure drops of the liquid flowing from inlet passageway 14aA and outlet passageway 14bA in'sequential or series stages such that at each stage and at valve seat 20A
the liquid does not drop below its vapor pressure and hence obviates cavitation.
It is'believed now readily apparent that the present invention provides a novel valve assembly for non-degassed liquid's wherein'the possibility of cavitation is greatly minim'ized or wholly eliminated. It is'a valve assembly which is quiet in operation and has a relatively long operative life by reason of being less subject to erosion and damage. The invention also provides a pilot operated modulating valve wherein cavitation is'obviated.
It is'not the in'kention hereof to restrict applications of the invention by the figures and description thereof, but rather it'should be understood that the present disclosure is' to illustrate the concepts and principles of the present inven-tion and that changes or alterations thereto obvious tG oneskilled in'the art wouId still come within'the scope of this' disclosure. Also, it'should be understood that the figures are deliberately not drawn to scale and are exaggerated in'some respects for clarity. Therefore, although the preferred embodi-' ments of the valve assembly of this'invention have been disclosed, it'shouId be obvious that the present dis'closure is'made by' way of example only and that varia'tions are possible without departing from the subject matter coming' within'the scope of the following claims, which claims are regarded as the invention.
A
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control of liquid flow which is less subject to erosion and quieter in operation than heretofore known liquid flow control valves. It is a further object of this invention to provide liquid flow control valve assembly which provides relatively free flow of liquid'therethrough.
In view of the foregoing, the present invention contemplates a novel valve assembly for controlling the flow of liqùid'which in its broadest aspect comprises a body portion having a liquid inlet communicating with a source of liquid' and a liquid outlet for passing liquid'from the valve assembly and at least one valve seat disposed between said inlet and said outlet. A movable valve member is disposed in the body portion for reciprocative movement between a position again'st said'valve seat to prevent flow of li~uid'from said inlet to said'outlet and a fully open position away from said valve seat to allow flow of liquid from the inlet to the outlet. A port means is located between said in'let and the valve seat which coacts with the movable valve member to provide a variable restriction to liquid'flow which is directly proportional to the variable flow area between said movable valve member and the valve seat.
In a narrower aspect of this'invention, the port means includes a stationary sleeve within'which the movable valve member is'disposed for reciprocative movement toward and away from said valve seat and which sleeve has a plurality of circum-ferentially spaced first openings, the flow areas of which varyin'size with the posit'ions of the movable valve member away from the valve seat. The port means further includes a bore in'the body portion spaced downstream of the valve seat and an extension of the movable valve member which projects beyond the valve seat into said'bore and for slidable movement relative thereto. The extension of the movable valve is constructed so that at least one second opening is defined between the end of the bore and the extension, and which second openin~ varies in size in direct proportlon to the distances of the movable valve member away from the valve seat. The first and second openings provide, in co-operation with the coaction of the movable valve member and valve seat, a series of pressure drops of relatively small magnitude to prevent, at each point, the liquid pressure falling below the vapor pressure of the liquid at the inlet of the valve body, thus, substantially min'imizing the possibilïty of producing the phenomenon known as cavitatioh.
A feature of the present invention is'that the movable valve member is a disc which is'slid`able in~a stationary sleeve and has a first and second reduced diameter portions, the first reduced diameter portion being adapted to seat or engage the valve seat, while the second reduced diameter portioh has a diametral notch in'the end thereof to form, with the end of the bore in'which it'is'slidably disposed, variable orifices or openings for the last in'the series of pressure drops of the liquid'in'flowing from the inlet to the outlet.
In a second embodiment of this inventioh, the stationary sleeve is'dimensioned so that it is`spaced from the fir'st reduced diameter portioh of the disc to form an annular space in'which a helical spring is disposed, the spacing between 25' the coils forming a plurality of restricted orif'ices or openings.
The spring is'connected to the disc so that, as the disc moves, the space between the spring coils vary in'size. Thus, the plurality of parallel openings vary in'flow area in'direct proportion to the change in the distance of the first reduced diameter portion of the disc from a seated posit'ion against the valve seat.
~2~
The invention will be more fully understood from the following detailed description thereof which considered in connection with the accompanying drawings wherein two embodiments of the invention are illustrated by way of example and in which:
Fig. 1 is a view in'cross section of a valve assembly according to a first embodiment of this invention for the control of liquid flow;
Fig. 2 is an enlarged fragmentary portion of a portion of the valve assembly shown in Fig'. l; and 0 Fig. 3 is an enlarged fragmentary portion of the valve assembly, similar to Fig. 2, showing a second embodiment of the present invention.
Now, referring to the drawings and more particularly to Figs. l and 2, the reference number 10 generally designates the valve assembly according to a first embodiment of this invention. It is'to be understood, while the valve assembly 10 is shown and will be described as a pilot operated, modulating, solenoid liquid'flow control valve assembly, the invention is not necessarily limited thereto. While the invention is'particuIarly desirable for pilot operated moduIating types of valves, it is' not limited thereto~ Therefore, the invention is shown and described in a pilot operated, moduIating, solenoid'liquid flow control valve assembly only for illustration purposes; that the invention has application to many types of liquid'flow control valves, particularly those that operate under high liquid temperatures and pressures and where valve movements are restricted to very small dis'tances, without departure from the scope and spirit'of this'invention.
The valve assembly 10 shown in'Figs. 1 and ~ briefly comprises a valve body 12 having a liquid'passageway 1~ which p~
has at one end an inlet port 16 and at the opposite end an outlet port 18. A main valve seat 20 is formed in passageway 14 between inlet and outlet ports 16 and 18. The portion oE
passageway 14 upstream from valve seat 20 will be identified as inlet passageway 14a, while the downstream portion of passageway 14 will be referred to as outlet passageway 14b.
A main movable valve member 22 (sometimes referred herein as a "main'disc") is mounted for reciprocative movement within' valve body 12 to posit'ions where the movable valve member is' abutting valve seat 20 and hence prevents flow of liquid through passageway 14 and a fully open posit'ion where the movable valve member is spaced away from valve seat 20 a miximum dis'tance.
Since valve assembly 10 is a pilot operated, modulating type valve, a pilot valve 24 is'mounted for reciprocative movement within'a bore in main valve member 22. In addition, the valve assembly 10 has an electromagnetic'assembly or solenoid motor 26 for controlling the operation of the pilot valve 24 and hence main valve member 22. The electromagnetic'assembly 26 is supported on a bonnet assembly 28 which is'conneGted and forms part of valve body 12. The bonnet assembly 2a generally comprises an elongated, non-magnetic', tubu-lar member 30 posi-tioned at an open end 32 within'a generally cylindric'al portion 34 of valve body 12, which portion 34 extends~angularly with respect to a valve portion 36 through which extends passageway 14. The tubular member 30 is'mounted in'valve portion 34 in spaced relation to valve seat 20 and coaxial therewith.
In operation of valve assembly 10, liquid'in'passage-way 14 supplied thereto through inlet port 16 from~a source of supply (not shown), enters the valve through bleed passageways 25 and 26 so that inlet pressure acts on all surfaces of piIot valve 24 and main dlsc 22, thus permitting spring 42 and return spring 44 to urge or bias pilot valve 24 and Inain movable valve member 22, respectively, in a seated or closed position, as shown. When it is'desired to open main movable valve member 22, the solenoid 26 is energized by a suitable source of electrical power (not shown). The magnetic flux lines thus generated upon energization cause pilot armature 38 to axially move again'st the force of a return spring 44.
This axial movement of pilot armature 38 against the bia'sing force of spring 44, also unseats pilot valve 24 without acting on the main'movable valve member 22 because of the lost motion provided between pin 48 and its associated slot 46 and pin 49 and its associa'ted slot 50 in~armature 38~ Continued energ-iz'ation and axial movement unseats main'movable valve member 22 to the full open position, assisted by the pressure dif'ferential across main'valve member 22. This'pressure differential across main valve member 22 is'caused by the opening or unseating of pilot valve 2'4 which communicates the interior of the valve with the outlet p~rt 18 and -thus effects a reduction in liquid pressure-acting a~ain'st the main'valve member surfaces in'a direction toward valve seat 20. Therefore, with inlet liquid'pressure still acting again'st the surface 52 via'bleed passageway 25 in'a stationary sleeve 56, and the pressure on the opposite surfaces of main'valve member 2~
reduced, a resuItant force is exerted on main valve member 22 in a direction to unseat the latter. Once liquid'pressure equilibrium across main'valve member 22 is'reached, any change in liquid inlet or outlet pressure will change the differential pressure across the main valve member and cause it's movement in response to such pressure dif'~erential. The large sudden pressure drop o~ the liquid as it flows past valve seat 20 into outlet passagway 14b and the resultant cavitation is avoided in valve assembly 10 in accordance with the present invention as hereinafter fully described.
As bes~ shown in Figure 2, valve assembly 10, main valve member 22 has a cylindrical portion 58, a first reduced diameter portion 60 and second reduced diameter portion 62 which has an end shaped and dimensioned to seat against valve seat 20. The main movable valve member 22 also has a third reduced diameter portion 64 and an enlarged diameter end portion or extension 66. The stationary sleeve 56, which is disposed between open end 32 of tubular member 30 and the valve seat 20, is so formed and dimensioned that the peripheral surfaces o~ portions 58 and 60 of main valve member 22 slidably engage the interior surface of sleeve 56. The valve seat 20 is formed along the inner edge of a ring element 68 which is suitably secured in housing or body portion 12 of valve assembly 10.
The interior surface of ring element 68 has a counterbored 2~ portion 70 which forms an enlarged diameter, inner annular surface and a reduced diameter, inner annular surface 74.
The inner annular surface 74 slidably engages the outer peripheral surface of enlarged diameter portion 66 of main disc 22. The second and third reduced diameter portions 6 and 64, enlarged portion 66 and annular surface of counter-bored portion 70 define an annular secondary inlet chamber 76. The end of enlarged portion 66 of main disc 22 has a diametral notch or groove 78 therein. This groove 78 co~
acts with upper peripheral edge portion 80 of inner annular surface 74 to define variable flow area orifices or outlets communicating annular inlet chamber 76 with outlet passage-way 14b.
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The stationar~ sleeve 56 has a reduced diameter end portion ~2, the inner surface of which slidably engages first reduced diameter portion 60 of main valve member 22.
The interstices between the main disc portion 60 and the inner surface of sleeve 56 is sealed by an O-ring seal 81 while the interstices between the adjacent surfaces of portion 58 of main disc 22 and sleeve 56 are sealed by an O-ring 83. ~ plurality of circumferentially spaced ports 84 are provided in reduced diameter end portion 82. These ports 34 coact with the end edge 86 of first reduced diameter end portion 60 of main disc 22 to provide variable flow area orifices or outlets communicating inlet passage-way 14a with the annulus 88 formed by the reduced diameter end portion 82 of sleeve 56, the end of ring element 6~, and reduced diameter portions 60 and 62 of main disc 22.
In operation, the orifices defined by ports 84 and end edge 86 of main valve member 22 function as first stage variable flow area restrictions upstream of valve seat 20.
The orifices defined by groove 78 and edge portion 80 form second stage variable flow area restricl:ions downstream of valve seat 20. The first and second stage variable flow area restrictions are so sized in relation to the total predetermined pressure drop of the liquid from inlet passageway l~a to outlet passageway 14b that at each stage and at valve seat 20 a pressure drop is achieved without the liquid falling below its vapor pressure and hence avoids the phenomenon known as cavitation. The total flow area at the first and second stages varies in direct proportional ~elationship to the movement of main valve member 22 toward and away from seat 20. Thus, valve assembly 10 automatically effects the avoidance of cavitation as changes _g _ :~,J :
,'' _' ,:
..~
in the pressure differential between the liquid in inlet passageway 14a and in outlet passageway 14b occur and cause modulation of main'valve member 22.
In Fig. 3 a portion of a valve assembly 90 is shown, which assembly constitutes~a second embodiment of this'inven-tion. Valve assembly 90 essentially differs from valve assembly 10 in that the fir'st stage variable flow area restrictions are defined by a helic'ally wound spring 92 in'stead of the coaction between first reduced diameter portion 60 of the main'valve member 22 and ports 84 in'stationary sleeve 56 as has been disclosed for valve assembly 10.
Accordingly, parts of valve assembly 90, similar to parts of valve assembly 10, will be identif'ied by the same reference number with the suffix A added thereto.
As shown in Fig'. 3, the stationary sleeve 56A does not have a reduced diameter portion 82 as does stationary sleeve-56, but is'of substantia'lly uniform diameter to form an annulus 94 between its inner surface and the outer peripheral surface of first reduced diameter portion 60A. In annulus 94 is disposed helical sprin~ 92 which is'preferably formed from wire of rectangular cross-section. The spring is'so dimensioned and assembled that as main'valve member or main'disc 22 moves between it's fully open and closed posit'ions, the space 96 between next adjacent coil's increase and decrease in'direct proportion to the movement of main'valve member 22A~ The spaces 96 form variable flow area restriction orif'ices which function to con~unicate inlet passageway 14aA, via'ports 84A, with space, in annulus 9~, formed~between the inner surface of the coils of spring 92 and outer surface of first reduced portion 60A of main'disc 22A and annulus 88A.
The valve assembly 90 is operationally the same as valve assembly 10 in that it provides for a controlled, sequential pressure drops of the liquid flowing from inlet passageway 14aA and outlet passageway 14bA in'sequential or series stages such that at each stage and at valve seat 20A
the liquid does not drop below its vapor pressure and hence obviates cavitation.
It is'believed now readily apparent that the present invention provides a novel valve assembly for non-degassed liquid's wherein'the possibility of cavitation is greatly minim'ized or wholly eliminated. It is'a valve assembly which is quiet in operation and has a relatively long operative life by reason of being less subject to erosion and damage. The invention also provides a pilot operated modulating valve wherein cavitation is'obviated.
It is'not the in'kention hereof to restrict applications of the invention by the figures and description thereof, but rather it'should be understood that the present disclosure is' to illustrate the concepts and principles of the present inven-tion and that changes or alterations thereto obvious tG oneskilled in'the art wouId still come within'the scope of this' disclosure. Also, it'should be understood that the figures are deliberately not drawn to scale and are exaggerated in'some respects for clarity. Therefore, although the preferred embodi-' ments of the valve assembly of this'invention have been disclosed, it'shouId be obvious that the present dis'closure is'made by' way of example only and that varia'tions are possible without departing from the subject matter coming' within'the scope of the following claims, which claims are regarded as the invention.
Claims (7)
1. A valve assembly for the control of flow of liquid comprising:
a) a body portion having a liquid inlet communicating with a source of liquid and liquid outlet for passing liquid from the valve assembly;
b) at least one valve seat in the body portion disposed between said inlet and said outlet;
c) an axially movable cylindrical valve member having (i) a seat engaging portion disposed in the body portion for reciprocative movement between a position against said valve seat to prevent flow of liquid from said inlet to said outlet and a fully open position away from said valve seat to allow flow of liquid from said inlet to said outlet;
(ii) a second flow controlling cylindrical portion on the inlet side of the seat engaging portion and having a diameter greater than the seat engaging portion to define together with the body portion a first chamber; and (iii) a third flow controlling cylindrical portion on the outlet side of the seat engaging portion having a diameter smaller than the seat engaging portion to define together with the body portion a second chamber separated from the first chamber by the valve seat and its seat engaging portion;
d) port means disposed between said inlet and the first chamber and coacting with the second flow controlling portion of movable valve member to provide a variable restriction to liquid flow into the first chamber which automatically varies in flow area in direct proportion to the variable flow area between said movable seat engaging portion and the valve seat; and e) second port means disposed between the outlet and the second chamber and coacting with the third flow controlling portion of the movable valve member to provide a variable restriction to liquid flow out of the second chamber which automatically varies in flow area in direct proportion to the variable flow area between the movable seat engaging portion and the valve seat of such magnitude that cavitation in the liquid does not occur.
a) a body portion having a liquid inlet communicating with a source of liquid and liquid outlet for passing liquid from the valve assembly;
b) at least one valve seat in the body portion disposed between said inlet and said outlet;
c) an axially movable cylindrical valve member having (i) a seat engaging portion disposed in the body portion for reciprocative movement between a position against said valve seat to prevent flow of liquid from said inlet to said outlet and a fully open position away from said valve seat to allow flow of liquid from said inlet to said outlet;
(ii) a second flow controlling cylindrical portion on the inlet side of the seat engaging portion and having a diameter greater than the seat engaging portion to define together with the body portion a first chamber; and (iii) a third flow controlling cylindrical portion on the outlet side of the seat engaging portion having a diameter smaller than the seat engaging portion to define together with the body portion a second chamber separated from the first chamber by the valve seat and its seat engaging portion;
d) port means disposed between said inlet and the first chamber and coacting with the second flow controlling portion of movable valve member to provide a variable restriction to liquid flow into the first chamber which automatically varies in flow area in direct proportion to the variable flow area between said movable seat engaging portion and the valve seat; and e) second port means disposed between the outlet and the second chamber and coacting with the third flow controlling portion of the movable valve member to provide a variable restriction to liquid flow out of the second chamber which automatically varies in flow area in direct proportion to the variable flow area between the movable seat engaging portion and the valve seat of such magnitude that cavitation in the liquid does not occur.
2. The apparatus of claim 1 wherein said port means is a stationary sleeve within which the movable valve member is disposed for reciprocative movement relative thereof, said sleeve having a plurality of circumferentially spaced openings, the flow areas of which vary in size with the positions of the movable valve member away from said valve seat.
3. The apparatus of claim 1 wherein said port means comprises a stationary sleeve surrounding and radially spaced from the movable valve member to define therebetween an annular space, the sleeve has a plurality of circumferentially spaced openings, and a helical spring disposed in said annular space and connected to the movable valve member so that as the latter moves, the coils of the spring move toward and away from each other to thereby provide a plurality of flow passages from said inlet to the outlet which vary in flow area proportionally to the open positions of the movable valve member.
4. In a pilot operated, modulating valve assembly a) a valve body portion having an inlet and outlet port;
b) an axially movable main valve member in the body portion having at least four coaxial cylindrical co-portions the first three of which have successively reduced diameters progressing from the inlet to the outlet ports followed by a fourth cylindrical portion having a diameter larger than the smallest of the first three;
c) said valve body portion having sleeve portions slidably receiving the first and fourth cylindrical portions of the valve member in guiding relationship and a valve seat disposed adjacent the second cylindrical portion;
d) said valve member having a disc carried by the second cylindrical portion to engage the valve seat in sealing relationship;
e) said body portion defining first and second chambers surrounding the second and third cylindrical portions, said chambers being separated by the disc;
f) first port means defined by the sleeve portions of the body portion and the first cylindrical portion of the valve member to connect the inlet port to the first chamber; and g) second port means defined by one of the sleeve portions and the fourth cylindrical portion of the valve member to connect the second chamber to the outlet, whereby unseating the disc establishes at least three sequential pressure drops from the inlet port to the first chamber across the face of the disc to the second chamber and from the second chamber to the outlet.
b) an axially movable main valve member in the body portion having at least four coaxial cylindrical co-portions the first three of which have successively reduced diameters progressing from the inlet to the outlet ports followed by a fourth cylindrical portion having a diameter larger than the smallest of the first three;
c) said valve body portion having sleeve portions slidably receiving the first and fourth cylindrical portions of the valve member in guiding relationship and a valve seat disposed adjacent the second cylindrical portion;
d) said valve member having a disc carried by the second cylindrical portion to engage the valve seat in sealing relationship;
e) said body portion defining first and second chambers surrounding the second and third cylindrical portions, said chambers being separated by the disc;
f) first port means defined by the sleeve portions of the body portion and the first cylindrical portion of the valve member to connect the inlet port to the first chamber; and g) second port means defined by one of the sleeve portions and the fourth cylindrical portion of the valve member to connect the second chamber to the outlet, whereby unseating the disc establishes at least three sequential pressure drops from the inlet port to the first chamber across the face of the disc to the second chamber and from the second chamber to the outlet.
5. The apparatus of claim 4 wherein said first port means comprises a stationary sleeve in the body portion surrounding and radially spaced from the movable valve member to define therebetween an annular space, the sleeve having a plurality of circumferentially arranged openings; and a helical spring disposed in the annular space and connected to the movable valve member so that as the latter moves the coils of the spring move toward and away from each other to thereby provide a plurality of flow passages upstream of said valve seat which vary in flow area in direct proportion to the distance the movable valve member is away from said valve seat.
6. The apparatus of claim 5 wherein said helical spring has a polygonal shape in cross section.
7. The apparatus of claim 4 wherein the fourth cylindrical portion is notched in its surface facing the outlet to form a flow path from the second chamber which increases in size in direct proportion to the disc movement away from the valve seat.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8512298A FR2565660B1 (en) | 1985-08-12 | 1985-08-12 | ANTICAVITATION VALVE ASSEMBLY |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1212886A true CA1212886A (en) | 1986-10-21 |
Family
ID=9322178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000486370A Expired CA1212886A (en) | 1985-08-12 | 1985-07-05 | Anti-cavitation valve assembly |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1212886A (en) |
| DE (1) | DE3524728C2 (en) |
| FR (1) | FR2565660B1 (en) |
| GB (1) | GB2177780B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3901032C1 (en) * | 1989-01-14 | 1990-02-08 | Danfoss A/S, Nordborg, Dk | |
| DE4416279A1 (en) * | 1994-05-07 | 1995-11-16 | Grau Gmbh | magnetic valve |
| JP3662159B2 (en) | 2000-02-16 | 2005-06-22 | 株式会社テージーケー | Solenoid driven pilot valve |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB822147A (en) * | 1955-02-08 | 1959-10-21 | Hattersley Ormskirk Ltd | An improved fluid control valve |
| GB806643A (en) * | 1955-08-31 | 1958-12-31 | Swiss Gas Stove Co Solothurn | Improvements in and relating to a device for regulating the quantity of a flowing medium discharged from a nozzle |
| US3151628A (en) * | 1961-05-01 | 1964-10-06 | Marquardt Corp | Flow regulator |
| US3521852A (en) * | 1966-12-12 | 1970-07-28 | Thomas S Gillis Jr | Throttle and shutoff valve |
| US3880399A (en) * | 1974-04-01 | 1975-04-29 | Fisher Controls Co | Multistage noise reducing flow control valve |
| US4041982A (en) * | 1976-01-09 | 1977-08-16 | Kieley & Mueller, Inc. | Double wall plug control valve |
| GB1569261A (en) * | 1976-10-20 | 1980-06-11 | Serck Industries Ltd | Fluid control valve |
| CH624196A5 (en) * | 1977-08-17 | 1981-07-15 | Ernst Franz Voegeli | Solenoid valve |
| DE2846294A1 (en) * | 1978-04-19 | 1979-10-31 | Crane Co | LOW-NOISE BARRIER |
| FR2431646A1 (en) * | 1978-07-21 | 1980-02-15 | Verdelet Alain | Tap for high pressure liquid feed - has plunger obturator of which tapered shaft traverse flanged washers form anti-cavitation chambers |
| US4407327A (en) * | 1981-04-24 | 1983-10-04 | Dresser Industries, Inc. | Flow control valve |
| FR2530772B1 (en) * | 1982-07-23 | 1986-01-31 | Rech Realisa Regulation | ELECTROMAGNETICALLY CONTROLLED VALVE FOR HIGH PRESSURE FLUID |
| US4699351A (en) * | 1984-07-11 | 1987-10-13 | Target Rock Corporation | Pressure responsive, pilot actuated, modulating valve |
-
1985
- 1985-07-05 CA CA000486370A patent/CA1212886A/en not_active Expired
- 1985-07-11 DE DE19853524728 patent/DE3524728C2/en not_active Expired - Fee Related
- 1985-07-19 GB GB8518310A patent/GB2177780B/en not_active Expired
- 1985-08-12 FR FR8512298A patent/FR2565660B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| GB8518310D0 (en) | 1985-08-29 |
| DE3524728C2 (en) | 1997-05-07 |
| GB2177780B (en) | 1989-11-22 |
| FR2565660A1 (en) | 1985-12-13 |
| GB2177780A (en) | 1987-01-28 |
| DE3524728A1 (en) | 1987-01-15 |
| FR2565660B1 (en) | 1990-08-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |