GB1570945A

GB1570945A - Valves

Info

Publication number: GB1570945A
Application number: GB1192777A
Authority: GB
Original assignee: Demangel Vence SA
Current assignee: Demangel Vence SA
Priority date: 1976-03-22
Filing date: 1977-03-22
Publication date: 1980-07-09
Also published as: ES457078A1; CH601706A5; BE852745A; CA1051407A; NL7703110A; DE2712447A1; FR2345645B1; FR2345645A1

Description

(54) IMPROVEMENTS RELATING TO VALVES (71) We, DEMANGEL -VENCE s.a.

(Société Ardennaise de Forge) of 34 rue de l'Abreuvoir 08106 - Charleville Merzieres, France, a French Company, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to valves. It is concerned with the type of valve described in French Patent No. 2186611, which comprises two rigid shells and an elastic membrane disposed between them and substantially co-planar with their opposed peripheral surfaces. The first shell has inlet and outlet ports open to the membrane over zones which can be mutually isolated. The second shell defines a control cavity closed by this membrane and connected by a permanently open passage with the inlet port and by a pilot passage with the outlet port.

The latter is strengthened by a grille for supporting said membrane.

This known valve has a number of drawbacks. For example, pressure losses are significant and cause malfunctioning at low pressures. Also, because of the need to use a very thin membrane, it is impossible to use the same one for a wide range of operating pressures, for example, from g/cm2 to Kg/cm2. A compromise between the mechanical resistance required of the membrane and its elasticity is practially impossible to achieve. Furthermore, leakage between the inlet and outlet is inevitable, the membrane not applying itself perfectly against the dividing element between inlet and outlet when the pressures are substantially equal. Also, the valve is limited in dimensions, particularly in the sections of the fluid passages, and in the pressures at which it can be used, by the essential but apparently irreconcilable requirements of resistance and deformation of the membrane.

The object of the present invention is to remedy these problems and to control efficiently the circulation of a gas or liquid. One preferred embodiment enables control of circulation of a liquid charged with solid particles to be achieved and avoids impulses when there are abrupt variations in pressure.

According to the present invention there is provided a valve comprising two rigid shells and an elastic membrane disposed between them and substantially coplanar with their opposed peripheral surfaces, the first shell providing inlet and outlet ports open to said membrane over zones which can be mutually separated, the second shell defining a control cavity closed by this membrane and connected by a permanently open passage with the inlet port and by a pilot passage to the outlet port, the latter being provided with fluid permeable means for supporting said membrane, the inlet and outlet zones being separated by a substantially straight dividing wall with a rib for cooperating with the membrane and projecting towards the second shell, and this rib, in a plane transverse to said wall and parallel to a reference plane defined by the axes of said ports, having a profile with rounded shoulders and, in a plane longitudinal with said wall and perpendicular to said reference plane, having a profile in which each extremity has an inflexion and merges tangentially mto the peripheral surface where the first shell is joined to said membrane and the second shell.

In a preferred form the rib projects proud of said peripheral surface of the first shell, the longitudinal profile of this rib being rectilinear with S-shaped curves at each end.

In another preferred form, the longitudinal profile of the rib is curved concavely towards the second shell. The maximum depth of the concavity of the rib, is between 1/lOth and 1/20th of the span of the control cavity opposite the rib. In this case, the second shell is formed asymetrically the control cavity being deeper opposite the outlet port than opposite the inlet port.

For a better understanding of the present invention some constructional forms will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section of a first valve according to the invention, the sectional plane being a plane of symmetry passing through the inlet and outlet3 Figure 2 is a section on the line II-II of Figure 1, Figure 3 is a plan view of the valve of Figure 1, as viewed in the direction of the arrow F, Figure 4 is a sectional view, corresponding to Figure 1, showing a valve with different inlet and outlet ports, Figure 5 is a sectional view, similar to Figure 1, showing another form of valve, Figure 6 is a section on the line VI-VI of Figure 5, Figure 7 is a partial plan view of the valve of Figure 5, as viewed in the direction of the arrow F, and Figure 8 is a section on the line VIII-VIII of Figure 7.

As in French Patent No. 21866L1, which generally relates to the form of valve which is the subject of the present Application, the valve comprises two rigid shells 1 and an elastic membrane or diaphragm disposed between them. This membrane is clamped by its periphery between the opposed surfaces 4 and 5 around the perimeters of the shells, which surfaces are parallel and virtu- ally coplanar, being separated only by the thickness of the membrane. This damping may be achieved by means of bolts, for example, and a perfect seal around the edge of the membrane can be obtained.The shell 1 has circular inlet and outlet ports 6 and 7 which are open to the membrane 3 at zones 8 and 9, and they can be mutually isolated as described below.

The shell 2 defines a control cavity 10 closed by this membrane. However, the cavity is connected to the inlet port 6 by a permanently open passage ii and to the outlet port by a pilot passage 12. By controlling the cross-sectional area of this pilot passage the pressure differential between the inlet port and the cavity 10 can be governed, and consequently the defcrmatioll of the membrane and the flow of fluid between the two ports 6 and 7.

To support the membrane 3 when the pressures are equalised between the inlet port 6 and the cavity lO. which pressures will be greater than that at the port 7, a grille 13 is mounted in the shell 1 acrnss the zone 9 and substantially flush with the surface 4.

In this first embodiment and as shown clearly in Figures 1 and 3, the zones 8 and 9 are of generally isosceles trapezoidal shape, with rounded corners, the long bases 8a and 9a being straight and parallel to one another on either side of a dividing wall 14. This wall is part of the shell 1 and separates the ports 6 and 7. The bases 8a and 9a are each longer than the diameter of the orifices 15 and 16 defined by the upper ends of the ports 6 and 7, where they will join to pipes or conduits, and the opposed portions 8b and 9b are rounded and concentric with these orifices.

It will be seen that there is a significant enlargement in cross-section of the port 6 between the orifice 15 and the associated zone 8 and, for the port 7, between the orifice 16 and the zone 9. This promotes flow of fluid between the two ports. The diverging sections are achieved by making the walls 17 and 18 of the inlet and outlet ports slope from orifices 15 and 16 progressively outwardly to the zones 8 and 9 to avoid turbulence and cavitation of the fluid.

The dividing wall 14 spans the cavity 10 and the deformable width of the membrane 3 (Figure 2) is much larger than the diame ter of the orifices 15 and 16 of the ports.

Thus with a relatively small deformation the membrane can distort sufficiently to make the area of passage 19 between the wall 14 and the deformed membrane 3a (Figure 2) at least equal to the area of the orifice 15 of the inlet port 6.

Thanks to the shape of the zones 8 and 9, to the slope of the walls 17, 18, to the presence cf 2 lengtely dividing wall 14 and to the surface provided by the membrane 3 deformable both in the transverse direction Figure 2) and in the longitudinal direction Figure 1), there is practically no loss of pressure, and the same membrane can serve operationally a considerable range of pressures. Figure 3 shows by the oval broken line 20 the outer boundary to which the BÇ3!1lbralle is defoahle, which boundary corresponds to the internal limit of the clamped periphery of the membrane between the shells.

The means described above enable flow without loss of pressure, but they are not sufficient to ensure a perfect sealed closure.

This is achieved ksy means to be described below.

lNle dividing wail 14 presents a rib 21 (Figures 1 and 2) which projects slightly proud of the surface 4 of the shell 1 into the cavity 10 of the shell 2. This provides a sup porting ridge for the membrane 3, putting it under light tension when it is closed, as may be seem from the full lines of Figure 2.

The transverse profile of the rib 21 (Figure 1), extending parallel to the reference plane defined by the axes 22 and 23 of the ports, has a central part 21a flanked at the edges of the zones 8 and 9 by rounded shoulders 21b and 21c.

The longitudinal profile of the rib 21, extending perpendicularly to this reference plane, has a straight central part 21d and, at each end where it joins the surface 4, a shallow S-shaped curve. In the example shown, each S-curve comprises a point of inflexion 21e to the outer side of which there is a substantially circular arcuate portion 21f merging into the surface 4, and to the inner side of which there is substantially parabolic portion 21g merging into the rectilinear portion 21d.

When the pressures in the inlet port 6 and the cavity 10 are equal, the membrane 3 tends to revert from its deformed position 3a towards its rest position, which should be co-planar with the surface 4. However the membrane cannot achieve this in practice and abuts against the rib 21. The weak internal tension which exists in the membrane is sufficient to ensure a fluid-tight seal along the zone of contact.

It is mentioned above that the walls 17 and 18 are shaped to obtain a progressive widening from the orifices 15 and 16 to the zones 8 and 9. More precisely, the portions 1 7a and 1 8a of these walls which define the dividing wall 14 are convergent towards the cavity 10 in order to ease the flow of fluid; the angle 'a' which they each subtend in relation to the plane of the surface 4 should be between 45" and 80". An advantage of this shape is that instead of the axes 22 and 23 of the ports being perpendicular to the surface 4 (as in Figure 1) they can be significantly inclined as shown in Figure 4. This can make it easier to connect the valve into the circuit it is intended to control.

The zone 9 has an area considerably greater than that of the outlet orifice 16 and this makes mounting the grille 13 no great problem. The grille covers substantially the whole of the zone 9, and its shape being indicated by 24 in Figure 3. The holes 25 can be punched, drilled or otherwise formed perpendicular to the plane of the grille, and the total area provided by these holes can be greater than the area of the orifice 16.

Figures 2 and 3 show that the crosssectional area of the permanent passage 11 between the inlet port 6 and the cavity 10 is less than the cross-sectional area of the pilot passage 12. Thus any excess fluid in the cavity 10 can be very easily bled out, which allows the counter pressure in the cavity to be regulated with precision and stability.

Such regulation is achievable by means of a pilot device 26 (Figure 2) associated with a branch from the passage 12 between the cavity 10 and the outlet port 7. This pilot device may be, for example, a manually operable tap, a float-operated valve, an electrically operated valve, or a thermostatically or electronically controlled device.

It is also easy to adapt the valve to make timed responses. It suffices in effect to determine the correspondance between the cross-sectional area of the permanent passage 11 and the capacity of the cavity 10.

In the further embodiment illustrated in Figures 5 - 8, many of the elements are identical and so are referenced correspondingly.

The particular point in this further embodiment is that the dividing wall 14 presents a projecting rib 31 with a different profile.

The transverse profile of the rib 31 (Figure 5), extending parallel to the plane of symmetry defined by the axes 22 and 23 of the ports, has a central part 31a flanked at the edges of the zones 8 and 9 by rounded shoulders 31b and 31c.

The longitudinal profile of this rib 31 (Figure 6) extending perpendicularly to said plane of symmetry, has a central curved portion 3 1d which is concave to the cavity 10.

In other words, the rib 31 is set back into the shell 1 and does not project proud of the surface 4.

Preferably, the rib curves in a circular arc (Figure 6) and its maximum depth H is advantageously between 1/10 and 1/20 of the span L of the cavity 10, this span being taken between the points where the rib 31 joins the surface 4.

In this further embodiment, the shell 2 is made asymmetric, having greater depth opposite the outlet port 7 than opposite the inlet port 6.

Thus, in the plane of symmetry, as seen in Figure 5, the interior profile of the shell 2 has a curved portion 31a merging sub span tially tangentially into the surface 5 and convex towards the inlet port 6. Preferably the curved portion 32a is a circular arc with a radius of curvature R2 centred at a point on the side of the surface 5 opposite to the ports 6 and 7.

The interior profile of the shell 2 (Figure 5) has another curved portion 32b opposite the outlet port 7, and it is concave towards that port. Preferably, the curved portion 32b is a circular arc with a radius of curvature RI centred at a point on the same side of the surface 5 as the ports 6 and 7.

These curved portions 32a and 32b merge directly one into the other at a point of inflexion, or there could be an intermediate rectilinear portion to which they are tangential.

The interior profile of the shell 2 is also curved perpendicularly to said plane of symmetry (Figure 6), preferably in a circular arc 32c concave towards the opposite shell 1. Thus it has a centre of curvature situated on the same side of the surface 5 as the ports 6and7.

The interior wall of the shell 2 causes the membrane 3 to flex asymmetrically when the pressure in the cavity 10 allows the membrane to lift clear of the rib, thus establishing communication between the ports 6 and 7 and allowing fluid, with minimal pressure loss, to flow from the inlet port 6, through the grille 13, and into the outlet port 7. The concavity of the rib 31 ensures that there is no restriction of the passage for fluid and that it will flow smoothly.

The permanent fluid passage 11 opens into the cavity 10 in a different manner from Figure 1 for it delivers more below the inlet port 6 than directly opposite the rib 31. Preferably the distance d of the delivery end of the passage 11 (Figure 5) from the rib 31 is substantially equal to one third of the distance D between the rib and the corresponding extremity of the cavity 10, measured in the plane of symmetry.

In the example shown, the passage 11 is formed (Figure 8) by an elbow 1 lea drilled in the periphery of the first shell 1 and by a groove 1 1b in the surface 5 of the second shell 2, the elbow 1 la opening into the groove 1 lib through a hole in the membrane 3.

This particular arrangement of the passage 11 combined with the specific form of the interior surface of the cavity 10 overcomes the problem of impulse shocks, because when there are abrupt changes of pressure, the membrane 3 deforms evenly in a progressive manner.

These improved valves can be used in any circuit carrying liquid under pressure, and are particularly useful in the chemical field.

WHAT WE CLAIM IS: 1. A valve comprising two rigid shells and an elastic membrane disposed between them and substantially coplanar with their opposed peripheral surfaces, the first shell providing inlet and outlet ports open to said membrane over zones which can be mutually separated, the second shell defining a control cavity closed by this membrane and connected by a permanently open passage with the inlet port and by a pilot passage to the outlet port, the latter being provided with fluid permeable means for supporting said membrane, the inlet and outlet zones being separated by a substantially straight dividing wall with a rib for cooperating with the membrane and projecting towards the second shell, and this rib, in a plane transverse to said wall and parallel to a reference plane defined by the axes of said ports, having a profile with rounded shoulders and, in a plane longitudinal with said wall and perpendicular to said reference plane, having a profile in which each extremity has an inflexion and merges tangentially into the peripheral surface where the first shell is joined to said membrane and the second shell.

2. A valve as claimed in claim 1, wherein the rib projects proud of said peripheral surface of the first shell, the longitudinal profile of this rib being rectilinear with S-shaped curves at each end.

3. A valve as claimed in claim 2, wherein each S-shaped curve has a point of inflection to one side of which there is a substantially parabolic portion where the curve joins the rectilinear portion and to the other side of which there is a substantially circular portion where it joins the peripheral surface.

4. A valve as claimed in claim 1, wherein the longitudinal profile of the rib is curved concavely towards the second shell.

5. A valve as claimed in claim 4, wherein the concave curve is substantially circular arc.

6. A valve as claimed in claim 4 or 5, wherein the maximum depth of the concavity of the rib is between 1/10 and 1/20 of the span of the control cavity opposite the rib.

7. A valve as claimed in claim 4, 5 or 6, wherein the second shell is formed asymmetrically, the control cavity being deeper opposite the outlet port than opposite the inlet port.

8. A valve as claimed in claim 7, wherein the interior profile of the second shell has, in the reference plane, a curved portion, preferably a circular arc, sub span tially tangential to the peripheral junction surface, this curved portion being opposite the entry port and convex towards it.

9. A valve as claimed in claim 7 or 8, wherein the interior profile of the second shell has, in the reference plane, a curved portion, preferably a circular arc, opposite the outlet port and concave towards it.

10. A valve as claimed in claim 7, 8 or 9 wherein interior profiles of the second shell, perpendicular to the reference plane, are curved, preferably in circular arcs, concavely towards the first shell.

11. A valve as claimed in anyone of claims 4 to 10 wherein the permanent passage between the entry port and the control cavity opens into the second shell opposite the entry port and nearer to the rib than to the extremity of the control cavity.

12. A valve as claimed in claim 11, wherein, measured parallel to the reference plane the delivery end of said permanent passage is substantially at one third of the distance between the rib and the corresponding extremity of the control cavity from the rib.

13. A valve as claimed as in any preceding claim wherein each port is divergent towards the membrane and the membrane and rib are such that the passage they can

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 6and7. The interior wall of the shell 2 causes the membrane 3 to flex asymmetrically when the pressure in the cavity 10 allows the membrane to lift clear of the rib, thus establishing communication between the ports 6 and 7 and allowing fluid, with minimal pressure loss, to flow from the inlet port 6, through the grille 13, and into the outlet port 7. The concavity of the rib 31 ensures that there is no restriction of the passage for fluid and that it will flow smoothly. The permanent fluid passage 11 opens into the cavity 10 in a different manner from Figure 1 for it delivers more below the inlet port 6 than directly opposite the rib 31. Preferably the distance d of the delivery end of the passage 11 (Figure 5) from the rib 31 is substantially equal to one third of the distance D between the rib and the corresponding extremity of the cavity 10, measured in the plane of symmetry. In the example shown, the passage 11 is formed (Figure 8) by an elbow 1 lea drilled in the periphery of the first shell 1 and by a groove 1 1b in the surface 5 of the second shell 2, the elbow 1 la opening into the groove 1 lib through a hole in the membrane 3. This particular arrangement of the passage 11 combined with the specific form of the interior surface of the cavity 10 overcomes the problem of impulse shocks, because when there are abrupt changes of pressure, the membrane 3 deforms evenly in a progressive manner. These improved valves can be used in any circuit carrying liquid under pressure, and are particularly useful in the chemical field. WHAT WE CLAIM IS:

1. A valve comprising two rigid shells and an elastic membrane disposed between them and substantially coplanar with their opposed peripheral surfaces, the first shell providing inlet and outlet ports open to said membrane over zones which can be mutually separated, the second shell defining a control cavity closed by this membrane and connected by a permanently open passage with the inlet port and by a pilot passage to the outlet port, the latter being provided with fluid permeable means for supporting said membrane, the inlet and outlet zones being separated by a substantially straight dividing wall with a rib for cooperating with the membrane and projecting towards the second shell, and this rib, in a plane transverse to said wall and parallel to a reference plane defined by the axes of said ports, having a profile with rounded shoulders and, in a plane longitudinal with said wall and perpendicular to said reference plane, having a profile in which each extremity has an inflexion and merges tangentially into the peripheral surface where the first shell is joined to said membrane and the second shell.

offer to fluid between the ports is at least equal to the minimal cross-section of the ports.

14. A valve as claimed in any preceding claim, wherein the angle subtended between the wall of each port adjacent the dividing wall and the membrane in its relaxed state is between 45" to 800, whereby the axis of each port can be perpendicular or inclined relatively to the membrane.

15. A valve as claimed in any preceding claim, wherein the permeable supporting means for the membrane covers the outlet port adjacent the membrane and the total area of holes in such means is at least equal to the minimum cross-sectional area of the outlet port.

16. A valve as claimed in any preceding claim, wherein the cross-sectional area of the permanent passage is less than the cross-sectional area of the pilot passage.

17. A valve as claimed in any preceding claim, wherein the capacity of the control cavity and the cross-sectional area of the permanent passage are related as a function of the response time selected for control.

18. A valve substantially as hereinbefore described with reference to Figures 1 to 3, Figure 4, or Figures 5 to 8 of the accompanying drawings.