WO1988001705A1

WO1988001705A1 - Fluid control valve

Info

Publication number: WO1988001705A1
Application number: PCT/AU1987/000303
Authority: WO
Inventors: Allen James Lowrie
Original assignee: Allen James Lowrie
Priority date: 1986-09-04
Filing date: 1987-09-04
Publication date: 1988-03-10

Abstract

A fluid control valve comprising a valve body (1) and a fluid flow passage (37) passing through the valve body. The fluid flow passage (37) includes an orifice (43) surrounded by a valve seat (35). A diaphragm (2) is moveable into and out of engagement with the valve seat for respectively closing and opening the orifice. An annular protrusion (83) is provided on the valve seat (35) and the diaphragm is deformed by the annular protrusion (83) when in engagement with the valve seat (35). The valve seat serves to limit the extent to which the annular protrusion can impress into the diaphragm and so protects the diaphragm from excessive degeneration. The embodiment disclosed is a spring loaded normally closed, solenoid operated, fine adjustment, easy maintenance dosing valve suitable for medical applications, with a diaphragm having a spigot (63) of larger diameter than the orifice (43).

Description

"FLUID CONTROL VALVE"

THIS INVENTION relates to a fluid control valve of the type having a diaphragm which co-operates with a valve seat in the valve to control flow of fluid through the valve.

Control valves of the type described above are commonly prone to leakage arising from degeneration of the diaphragm as a consequence of the diaphragm moving into and out of engagement with the valve seat over an extended period of time.

The present invention seeks to provide a novel and useful fluid control valve so constructed as to reduce the likelihood of valve leakage.

In one form the invention resides in a fluid control valve comprising a valve body, a fluid flow passage passing through the valve body, the fluid flow passage including an orifice surrounded by a valve seat, a diaphragm moveable into and out of engagement with the valve' seat for respectively closing and opening the orifice, and an annular protrusion provided on the valve seat, the diaphragm being deformed by the annular protrusion when in engagement with the valve seat.

Preferably the cross-sectional dimension of the annular protrusion in the plane of the valve seat is significantly smaller than the corresponding dimension of the valve seat. Because of this feature, the valve seat provides a relatively large seating area for the diaphragm and the annular protrusion facilitates secure sealing. The valve seat limits the extent to which the annular protrusion can deform the diaphragm when it is impressed into the diaphragm and so protects the diaphragm from excessive degeneration.

Preferably, the annular protrusion is located adjacent the inner periphery of the valve seat.

Preferably, the , annular protrusion has a cross-sectional shape which converges in the direction away from the valve seat to present a sharp edge to the diaphragm.

Preferably, the diaphragm includes a central portion which is stiffened so as to undergo no significant flexing movement as the diaphragm moves into and out of engagement with the valve seat, the central portion being of a size relative to the orifice so as to cover the orifice when the diaphragm is in engagement with the valve seat. The central portion is preferably stiffened by thickening of the central portion on the side thereof opposite to the valve seat. Preferably, said thickening is provided by a projecting portion extending from the plane of the diaphragm in the direction away from the valve seat, said projection portion being secured to an actuating means for moving the diaphragm into and out of engagement with the valve seat.

Preferably, the actuating means includes means for biassing the diaphragm into engagement with the valve seat. The actuating means may be an electro-mechanical device including a plunger operable by a solenoid for moving the diaphragm into and out of engagement with the valve seat. With such an arrangement, the plunger is preferably provided with a recess which receives the projecting portion of the diaphragm.

Preferably, the diaphragm is provided with a thickened rim portion at the outer periphery thereof, and the valve further includes means for clampingly engaging said thickened rim portion for supporting the diaphragm for movement into and out of engagement with the valve seat. The clamping means preferably includes a projecting annular ridge portion for deforming said rim portion to facilitate retention of the diaphragm in the clamped condition. The annular ridge portion is preferably disposed on the side of the rim portion of the diaphragm opposite to the valve seat.

Preferably, said clamping engagement of the rim portion of the diaphragm is between a surface provided on the valve body and a clamping ring, portion of the clamping ring being received against a further surface of the valve body to limit the extent of movement of the clamping ring towards said surface and thereby limit the clamping force applied to the rim portion of the diaphragm.

In another form the invention resides in a diaphragm as constructed as set forth in any one of the preceding paragraphs.

This invention will be better understood in the light of the following description of one specific embodiment thereof. The description is made with reference to the accompanying drawings wherein:-

Fig. 1 is a sectional elevation of the fluid control valve;

Fig- 2 is an end elevation of the fluid control valve;

Fig. 3 is a side elevation of Fig. 1;

Fig. 4 is an enlarged fragmentary view of the valve, showing the diaphragm in engagement with the vale seat;

Fig. 5 is a view similar to Fig. 4 except that the valve is shown out of engagement with the valve seat; and

Fig. 6 is a section along the line b-b of Fig. 3.

The embodiment is directed towards a fluid control valve having a diaphragm actuated by an electro-mechanical device.

The fluid control valve comprises a body ϊ having a control chamber 33 therein. One wall of the control chamber is defined by a diaphragm 2. The body is preferably formed of polypropylene and the diaphragm formed of santoprene to enable use with aggressive fluids.

The ..body 1 contains a passage 37 for fluid flow from an inlet 39 to an outlet 41 and is provided with a central boss portion 25 which houses the central control chamber 33 interposed between the inlet and outlet of the passage. The boss portion 25 forms a- well having a central axis 27 disposed orthogonally to the central longitudinal axis 38 of the passage. The chamber is located centrally within the well and is circumscribed by an intermediate boss 69. The chamber is provided with an entry port 43 which communicates with the inlet 39 of the passage, and an exit port 45 which communicates with the outlet 41 of the passage. The chamber 33 houses a fixed valve seat 35 described in more detail later.

The electro-mechanical device for actuating the diaphragm includes a solenoid 36 which is adapted to be fitted to the body 1 such that its actuating end is received within the well and its other end projects outwardly therefrom in coaxial alignment with the central axis 27 of the well. The solenoid is housed within a cup-shaped cover 9 which is intimately accommodated at its open end within the socket formed by the well.

The solenoid 36 is provided with an encapsulated coil 7 which is fixedly mounted to a central stem 10 disposed co-axially with the central axis 27. The stem is maintained in position within the cover^" 9 by- means of a threaded tube nut 11.which forms a sleeve about the end of the stem and which may be threadedly engaged within a threaded aperture provided at the end of the cover. The coil 7 is concentrically mounted towards the inner end 47 of the stem such that a central axial recess is provided therein. The inner end 47 of the stem is formed with a spigotted portion to define an annular region at the terminal end of the recess, so as to accommodate an annular stem nose piece 4. The nose piece 4 is adapted to be threadedly mounted within the recess upon the spigotted portion of the stem end 47. The stem 10 is formed with a central longitudinal bore 55 which is adapted to accommodate one end of a compression spring 6. The bore is axially threaded along a substantial portion thereof to threadingly receive a grub screw 12 which forms a stop for the other end of the spring. The axial location of the grub screw within the bore may be adjusted by means of a screw driver of the like to vary the tension of the spring.

The stem nose piece 4 itself is provided with a central bore 48 which accommodates a plunger in the form of armature 5 of the solenoid to allow relative axial movement thereof with respect to the coil and stem.

The stem nose piece 4 is formed with an enlarged annular head 59 at its outer end which defines an intermediate shoulder 57 adjacent the outer end of the coil 7. The head 59 is externally threaded to screw into the correspondingly internally threaded intermediate boss 69 and consequently mount the inner end of the ^* solenoid to the well of the main boss portion 25. To facilitate mounting of the cover 9 to the boss portion 25, retain the nose piece and guide the magnetic flux through the armature, a coil cheek 8 is fitted within the well. The cheek plate is provided with a central collar portion 61 and a central aperture 62 co-axially aligned with the central axis 27 of the solenoid and well. The collar portion 61 is adapted to engage the intermediate shoulder 57 of the stem nose piece 4 and retain the same in axial relationship with the control chamber 33. The outer circumference of the coil cheek 8 is threaded to screw into the correspondingly internally threaded boss portion 25. The coil cheek 8 is provided with an outer spigot portion 65 which abuts the inner end of the coil 7 and forms an annular recess in conjunction with the outer end of the boss portion 25 to accommodate the open end of the cover 9.

The armature 5 is provided with an inner recess 53 which is co-axially aligned with the central axis of the bore 55 and which confronts the same at the inner end of the armature so as to accommodate the other end of the spring 6. Consequently, the spring operates to maintain an axial force on the armature biasing the same towards the control chamber 33. The outer end of the armature 5 is provided with an aperture 54 to securely receive a central plug 63 formed integrally with the diaphragm 2 disposed within the central chamber 33. The plug 63 is of a larger diameter than the orifice 43, as best seen in Figs. 4 and 5.

The valve seat 35 is disposed • centrally of the intermediate boss 69 in coaxial arrangement with the central, axis 27 of the well. The valve seat forms an inner boss concentric with the intermediate boss 69 and defines a central orifice provided in the entry port 43 of the passage 37 into the chamber 33.

The inner circumference of the intermediate boss 69 is stepped to define an inner annular recessed seat 71 having a radially disposed stopper portion 73 to seat the outer periphery of the diaphragm 2, and an intermediate shoulder 75 of slightly larger diameter than the recessed seat 71, to accommodate a clamping ring 3. The diaphragm 2 is formed with a thickened rim portion 77 around its outer periphery and an annular portion 78 extending between the rim 77 and the central plug 63. The rim portion 77 fits within the recess seat 71 to abut against the stopper portion 73 so that axial movement of the rim portion towards the seat is opposed. The clamping ring portion 3 is provided with a sufficient radial extent to overlie the other side of the rim portion of the diaphragm, and is formed with an axially projecting ridge portion 79 to engage the rim portion of the diaphragm and partially penetrate the same in response to the application of an axial force applied thereto against the rim. The clamping ring portion 3 is held into engagement with the rim portion 77 and the inner shoulder 75 by a retaining means which comprises the outer end of the enlarged head portion 59 of the stem nose piece 4. Consequently, axial force towards the rim portion 77 may be applied to the clamping ring portion by axial movement of the stem nose piece 4 towards the stopper portion 73. The penetration of the ridge 79 of the clamping ring 3 into the rim portion 77 of the diaphragm, effectively opposes radial movement of the rim portion from its clamped engagement between the stopper portion 73 and the clamping ring 3. Consequently, the diaphragm 2 is mounted in the body 1 to confront the valve seat 33 and the orifice provided therein. The shoulder 75 serves to limit the extent to which the clamping ring 3 can press against the rim portion 77 of the diaphragm. This limitation serves to ensure that the diaphragm rim portion is compressed sufficiently to ensure that the ridge portion 79 penetrates the diaphragm rim while not impeding flexing movement of the annular portion 78. The valve seat 35 is formed with an annular seating portion 81 circumscribing the orifice of the entry port. The seating portion 81 is formed with a generally planar face disposed substantially orthogonally to the central axis or marginally offset therefrom, which is confronted by the central portion of the diaphragm. The seating portion is also provided with an axially projecting annular protrusion 83 (hereinafter called a puddle flange) which has a transverse dimension in a direction parallel to the face significantly smaller than the corresponding dimension of the face. Because of the relatively large contact area of seating portion 81, there is little likelihood of the seating portion cutting into the diaphragm.

The diaphragm is particularly disposed such that the central portion thereof • can be moved in conjunction with the axial movement of the armature 5 to engage the planar face of the seating portion in sealing engagement therewith and thus close the valve, and to disengage the same and thus open the valve. In the present embodiment, the provision of the compression spring 6 within the armature and stem normally biases the diaphragm into engagement with the seating portion of the valve seat effecting closure of the valve. Consequently upon energisation of the coil, the armature is retracted within the recess of the coil to open the valve.

The puddle flange 83 particularly facilitates secure sealing of the contacting portion of the diaphragm against the seating portion of the valve seat, but does not cause degeneration of the contacting portion as the depth to which the puddle flange can be impressed into the diaphragm is limited by the planar seating portion 81.

Electrical energy is provided to energise the coil through wires 87 which enter the solenoid via a side boss 85 provided on the cover 9.

The operation of the valve will now be described in further detail.

When the encapsulated coil 7 is energised a magnetic field grows through stem 10, tube nut 11, cover 9, coil cheek 8, armature 5 and back to stem 10. The armature 5, being a moving part, is attracted to the stem 10 thus lifting the diaphragm 2 from the -valve seat 35 in body 1 and permitting fluid flow from the inlet 39 to the outlet 41 of the passage 37. The armature 5 moves in the magnetic field because the surrounding item, stem nose piece 4 is made from brass and has little or no magnetic permeability. The magnetic flux concentration at the face 10a of the stem 10 is at a maximum (with very little fringing) due to the presence of a copper "shading ring" 19 embedded therein, which is, in effect, . a single turn coil. This ring 19 will have an induced current (from the magnetic field) which will produce its own magnetic field in the form of a tore (or ring) which focuses the main magnetic field.

When the coil is de-energised, the armature 5 is returned to its normal position under influence of the spring 6 and so the diaphragm is returned into sealing engagement with the valve seat.

Because of the construction of the diaphragm, there is little likelihood of fracture lines or planes developing in the diaphragm as the diaphragm moves into and out of engagement with the valve seat. In any event, because the centre plug 63 in the diaphragm 2 is of a larger diameter than the orifice, the valve will continue to function even if the flexing portion of the diaphragm 2 (being the annular portion 78) should rupture, thus giving a "fail safe" condition. Corrosion of parts of the valve may, however, commence should such a rupture occur as only an intact diaphragm provides a barrier against aggressive fluids.

The spring adjusting screw 12 permits the valve to be "fine-tuned" into different pressure ranges (even from super-atmospheric to sub-atmospheric pressures) by adjusting tension on the spring 6.

Tube nut 11 locates the encapsulated coil centrally thus ensuring no trapped lead wires, provide an adequate air space for coil heat dissipation and holds the whole assembly together.

The assembly design permits the quick and easy removal of the "wet end" of the valve for maintenance whilst leaving the coil and cover intact in installation. Applications of the solenoid valve include it operating primarily as a "dosing valve" to selectively admit a metered quantity of fluid into a mainstream fluid.

The diaphragm or clamp 3, stem nose piece 4, armature 5 and stem 10 could all be gold plated to ensure against corrosion if the diaphragm should rupture. This feature would be most desirable in applications in the medical area.

It should be appreciated that the scope of the present invention is not limited to the particular embodiment described herein. For instance, the solenoid operation could be replaced by a fluid pressure actuator or other actuating system.

Claims

THE CLAIMS defining the invention are as follows:

1. A fluid control valve comprising a valve body, a fluid flow passage passing through the valve body, the fluid flow passage including an orifice surrounded by a valve seat, a diaphragm moveable into and out of engagement with the valve seat for respectively closing and opening the orifice, and an annular protrusion provided on the valve seat, the diaphragm being deformed by the annular protrusion hen-in engagement with the valve seat. a

2. A fluid control valve according to claim 1 wherein the cross-sectional dimension of the annular protrusion in the plane of the valve seat is significantly smaller than the corresponding dimension of the valve seat.

3. A fluid control valve according to claim 2 wherein the annular protrusion is located adjacent the inner periphery of the valve seat.

4. A fluid control valve according to claim 3 wherein the portion of the valve seat to the side of the annular protrusion is substantially planar.

5. A fluid control valve according to any one of the preceding claims wherein the annular protrusion has a cross-sectional shape which converges in the direction away from the valve seat to present a sharp edge to the diaphragm.

6. A fluid control valve according to any one of the preceding claims wherein the diaphragm includes a central portion which is stiffened so as to undergo no significant flexing movement as the diaphragm moves into and out of engagement with the valve seat, the central portion being of a size relative to the orifice so as to cover the orifice when the diaphragm is in engagement with the valve seat.

7. A fluid control valve according to claim 6 wherein said central portion is stiffened by thickening of the central portion on the side thereof opposite to the val-v seat.

8. A fluid control valve according to claim 7 wherein said thickening is provided by a projecting portion extending from the plane of the diaphragm in the direction away from the valve seat, said projecting portion being secured to an actuating means for. moving the diaphragm into and out of engagement with the valve seat.

9. A fluid control valve according to claim 8 wherein said actuating means includes means for biassing the diaphragm into engagement with the valve seat.

10. A fluid control valve according to claim 8 or 9 wherein the actuating means is an electro-mechanical device including a plunger operable by a solenoid for moving the diaphragm into and out of engagement with the valve seat.

11. A fluid control valve according to claim 10 wherein said plunger is provided with a recess which receives the projecting portion of the diaphragm.

12. A fluid control valve according to any one of the preceding claims wherein the diaphragm is provided with a thickened rim portion at the outer periphery thereof, and wherein means are provided for clampingly engaging said thickened rim portion for supporting the diaphragm for movement into and out of engagement with the valve seat.

13. A fluid control valve according to claim 12 wherein said clamping means includes a projecting annular ridge portion for deforming said rim portion to facilitate retention of the diaphragm in position.

14. A fluid control valve according to claim 13 wherein said annular ridge portion is disposed on the side of the rim portion of the diaphragm opposite to the valve seat.

15. A fluid control valve according to claim 12, 13 or ,14 wherein said rim portion of the diaphragm is clampingly engaged between a surface provided on the valve body and a clamping ring, portion of the clamping ring being received against a further surface of the valve body thereby to limit the clamping force applied to the rim portion of the diaphragm.

16. A fluid control valve according to claim 15 wherein said annular ridge is provided on the clamping ring.

17. A fluid control valve substantially as hereindescribed with reference to the accompanying drawings.

18. A diaphragm for a fluid control valve, the diaphragm being constructed as set forth in any one of the preceding claims.

19. A diaphragm for a fluid control valve substantially as hereindescribed with reference to the accompanying drawings.