IL107447A - Electrical diaphragm valve - Google Patents

Description

107447/3 Electrical Diaphragm Valve Aran Engineering Development Ltd tt"i>3 mivai ^ij>» pN Netafim Irrigation Equipment & Drip Systems Kibbutz Hatzerim 1973 1973 o>->-*n The inventor: Youval KATZMAN C. 90484 - 1 - 107447/2 FIELD OF THE INVENTION This invention relates to electrical valves such as are used, for instance, in automatic sprinklers and the like.

BACKGROUND OF THE INVENTION Electrical valves such as are connected in the water inlet feed of a garden sprinkler are typically solenoid operated. Such valves include a sealing means which is opened by a linear armature which itself is actuated by a solenoid. Such valves are supplied normally closed: the closure itself being effected by means of a spring mechanism. Thus, in effect, the force of the solenoid overcomes the spring bias in order to open the valve.

A disadvantage with such valves, as is known, is that in order to maintain the valve in an open state, electrical energy must be constantly supplied for actuating the solenoid.

Electrical valves are also known wherein the solenoid is replaced by a conventional electrical motor. A major advantage of using an electrical motor over the use of the solenoid is that power need be supplied to the motor only in order to open and close the valve: there being no need to supply current to the motor once an equilibrium position of the valve has been achieved. - 2 - 107447/2 Notwithstanding the obvious advantages of using a motor-operated valve over a solenoid-operated valve, there exists a difficulty in conforming such motor-operated valves to existing installations. Specifically, installations which assume the use of solenoid-operated valves are so constructed that energy is provided only in order to open the valve and to maintain it in the open state, whereupon disconnecting the power supply causes the valve to return to the closed position under the influence of the spring bias.

Regardless as to whether the operating mechanism is solenoid or motor operated, such valves are typically provided with a fluid inlet passage extending into a recess within which there is provided an "0" ring, whereby, when a closure member in the form of a rod is inserted into the "0" ring, the fluid inlet passage is sealed, thereby closing the valve. Such an arrangement represents a conventional piston-type valve which is characterized by the fact that the force acting on the piston head is exactly equal to the area of the piston multiplied by the pressure of the fluid acting thereon. This is distinct from diaphragm-type valves which, when open, are subjected to a greater force than the closure force, owing to the increased area upon which the fluid pressure is exerted. The additional area is an inevitable consequence of the need to provide for buckling of the diaphragm, thereby requiring that the area of the diaphragm extends beyond the area of the fluid inlet passage which is to be sealed.

This having been said, there are disadvantages associated with piston valves. First, the closure force must take into account frictional forces between the piston rod and the "0" ring and is therefore always somewhat greater than the theoretical minimum described above. Secondly, in time, owing to wear and tear, the piston rod abrades the inside surface of the "O" ring, thereby causing the valve to leak.

Such leakage is, of course, avoided in diaphragm valves, as are also the frictional forces. On the other hand, the additional surface area of the diaphragm, thereby requiring an increased enclosure force, is sufficiently disadvantageous to militate against their use in preference to piston-type valves, notwithstanding the disadvantages of the latter.

It would clearly be desirable somehow to overcome the sole disadvantage associated with diaphragm valves whereby the maximum closure force would be equal to the fluid pressure multiplied by the area of the fluid inlet, whilst enjoying all the other advantages associated with diaphragm valves over piston-type equivalents.

In diaphragm valves, the diaphragm itself is disposed between the fluid inlet to be sealed and a closure member having a surface area greater than that of the inlet passage. The valve is closed by forcing the closure member against the diaphragm, so as to distort the diaphragm on to the fluid inlet, thereby sealing the valve. If the closure member is operated via an electrical motor, then one way to apply sufficient force to the closure member would be to employ a correspondingly powerful motor. However, it is usually a requirement to miniaturize, as much as possible, the motor in order to reduce the valve size, as well as its cost. Miniature motors are usually incompatible with the requirement to provide a high closure force. Therefore, a transmission mechanism must be employed in order to increase the effective motor force. However, this can only be done at the expense of increasing the velocity ratio of the mechanism, thereby resulting in slow operation of the valve. During the time which is thus taken for the valve to close, fluid leakage occurs and this is unsatisfactory.

SUMMARY OF THE INVENTION It is an objection to provide a diaphragm valve in which the drawbacks associated with hitherto-proposed valves are substantially reduced or eliminated. - 4 - 107447/2 It is a further object of the invention to provide such a valve which is motor-operated and which can be substituted for existing solenoid-operated valves in installations constructed therefor.

According to a broad aspect of the invention, there is provided a diaphragm valve comprising a valve casing; inlet and outlet ports of said casing; an inner wall surface of said casing; one of said ports opening into said wall surface and having a peripheral valve seating formed in said wall surface; a flexible diaphragm juxtaposed with respect to said wall surface; a toggle member mounted in said casing and rotatable about a pivot axis thereof between first and second positions; a pair of spaced apart abutment members forming part of or associated with said toggle member and adapted to bear on a first surface of said diaphragm with a first of said abutment members juxtaposed with respect to said valve seating, and externally actuated drive means for pivotally displacing said toggle member into opening and closing said one port; the arrangement being such that fluid pressure generated between said wall surface and spaced apart locations of a second and opposite surface of said diaphragm pivotally displaces said toggle member in opposite senses whereby displacement in one sense results in said first abutment member sealingly biasing said diaphragm against said valve sealing.

Preferably, the operating means includes an electric motor coupled to the toggle member via a transmission system comprising a pair of gear wheels, such that several rotations of the electric motor are required in order to operate the toggle member. The speed of operation of the valve is increased by arranging for the transmission system to apply an impulse to the toggle member, whenever it is desired to change the state of the valve from open to closed, or vice versa.

Preferably, the motor is operated by a source of d.c. power and is coupled to the toggle member and is responsive to a first polarity voltage 2 pulse for urging the toggle member into the first position and is responsive to a second polarity voltage pulse for urging the toggle member into the second position. A switching circuit is connected to the motor for decoupling the electrical d.c. motor from the source of d.c. electrical power only when it is required to urge the toggle member from the second position to the first position.

BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how the same may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 shows schematically a detail of a diaphragm valve according to the invention wherein fluid flows in a first direction and the valve is fully closed; Fig. 2 shows schematically a detail of a valve according to the invention wherein fluid flows in a second direction and the valve is fully closed; Fig. 3 shows schematically a detail of the valve illustrated in Fig. 1 in an intermediate, partially open position; Figs. 4a and 4b show graphically a comparison of respective energy profiles for the valves shown in Figs. 1 and 2, and prior art piston and diaphragm valves; Fig. 5 shows a partial sectional elevation of a detail of a valve according to the invention, having a motor-operated toggle' member; Fig. 6 is a perspective view of the arrangement shown in Fig. 5; Figs. 7a, 7b and 7c show a detail of the toggle member illustrated in 107447/2 Fig. 8 shows a further detail of the toggle member illustrated in Fig. 5; Fig. 9 shows schematically an alternative embodiment of the invention employing an unbalanced toggle member; Fig. 10 is a sectional view of a closed diaphragm valve employing a operating mechanism according to the invention; Fig. 11 is a cross-sectional view of the valve shown in Fig. 10 through section XI - XI; Fig. 12 is a sectional view of the valve shown in Fig. 10 when open; ■■ and Fig. 13 is a cross-sectional view of the valve shown in Fig. 12 through the section ΧΪΪΪ - ΧΪΪΪ.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Figs. 1 and 2, there is shown schematically a detail of a valve depicted generally as 1, comprising a casing 2 (only part of which is shown) having an inlet port 3, an outlet port 4 and an inner wall surface 5 surrounding the outlet port 4. Thus, in the configuration shown in Fig. 1, the outlet port 4 opens into the wall surface 5 so as to define a peripheral valve seating 11 formed in the wall surface 5 and depending from which is a fluid inlet 12 into which fluid flows from the inlet port 3 in a first direction depicted by arrow A. In the configuration shown in Fig. 2, the inlet port 3 opens into the wall surface 5 so as to define the peripheral valve seating 11, depending from which is the fluid inlet 12 into which fluid flows towards the outlet port 4 in a second direction depicted by arrow B (Fig. 2).

In both configurations, a flexible rubber diaphragm 13 is disposed above the valve seating 11 and is acted upon within an area of the fluid inlet - - 12 by a first end 14 of toggle member 15 which constitutes a closure member which is free to rotate about a pivot axis 16 thereof under the action of a motor M, constituting an external drive means. The first end 14 of the toggle member 15 contacts the diaphragm 13 via a first abutment member 17 whilst a second end 18 of the toggle member 15 opposite the first end 14 thereof contacts the diaphragm 13 via a second abutment member 19 spaced apart from the first abutment member 17. The toggle member 15 is balanced in that the pivot axis 16 is equidistant from the first and second ends 14 and 18, respectively. The abutment members 17 and 19 may, if desired, be formed integral with the toggle member 15.

In either of the two situations depicted in Figs. 1 and 2, fluid pressure generated between the wall surface 3 and a lower surface of the diaphragm 13 below the second abutment member 19, tends to pivotally displace the toggle member 15 so as to apply a closing force to the first abutment member 17 into sealingly biasing the diaphragm 13 against the valve seating 11. When the first abutment member 17 acts upon the diaphragm 13 with sufficient force to seal the valve seating 11, the maximum closure or opening, as the case may be, force is close to the fluid pressure P multiplied by the cross-sectional area A of the fluid inlet 12. Thus, specifically, in the situation shown in Fig. 1, when the valve is sealed, fluid acts upwards in the direction of arrow A so that the force acting on the underside of the diaphragm 13 is equal to P.A. This, then, is the closure force which must be applied by the toggle member 15 in order to close the valve.

On the other hand, in the situation shown in Fig. 2, when the valve is sealed, no fluid flows through the fluid inlet 12 and the pressure thus acting on the underside of the diaphragm 13 within the area A of the fluid inlet 12 is zero. However, a pressure P still acts on the remaining area of the diaphragm 13, and impinges against a distorted area thereof within the 107447/2 vicinity of the valve seating 11, thereby tending to lift the diaphragm 13 from the valve seating 11. At the same time, owing to the presence of fluid between the wall surface 3 and the diaphragm 13, the pressure P is applied to the second abutment member 19 which exerts a force against the second end 18 of the toggle member 15. This more than counteracts the tendency for the toggle member 15 to lift from the valve seating 11 owing to the fact that the area of the second abutment member 19 to which the pressure P is applied exceeds that of the distorted area 17 of the diaphragm. Thus the opening force which must be applied against the toggle member 15 in order to open the valve 1 is still very nearly equal to P.A.

The arrangement shown in Figs. 1 and 2, therefore, provides for the use of a diaphragm valve wherein the closure or opening force is proportional to the cross-sectional area of the inlet passage (as is the case for piston valves) as opposed to an enlarged area of the diaphragm, as is the case in hitherto-proposed valves employing diaphragms. On the other hand, since a diaphragm is employed, frictional forces and cylinder abrasion, typically associated with piston valves, are avoided.

Fig. 3 shows an intermediate state in the arrangement shown in Fig. 1 prior to complete closure thereof. Thus, the toggle member 15 is in a partially rotated position such that the flexible diaphragm 13 does not completely engage the valve seating 11 such that fluid seeps through the opening as shown by the arrow F. As the flexible diaphragm 13 approaches the valve seating 11, the resultant opening will become diminished in cross-section so that the fluid pressure across the opening increases. Consequently, the fluid pressure of the fluid remaining inside the housing is greater than P but since it is uniformly distributed over the complete area of the diaphragm 13 within the housing, and since furthermore the toggle member 15 is balanced, the net force on the two abutment members 17 and 19 is equal. Thus, only when the abutment member 17 completely depresses the diaphragm 13 into sealing engagement with the valve seating 11, the residual fluid pressure within the housing is negligible whilst the fluid pressure outside the housing in the direction of the arrow A is equal to P. This pressure acts only on the area of the diaphragm 13 in contact with the valve seating 11 whose cross-sectional area is A. Thus, at the moment of actual closure, the force which must be applied on to the abutment member 17 in order to seal the valve is exactly equal to the product of P.A, as noted above.

Reference is now made to Fig. 4a of the drawings which compares graphically the force required for closing the valve shown in Fig. 1 with the corresponding forces required when a conventional diaphragm or piston valve is employed. Thus, the upper curve designated D represents the situation when a conventional diaphragm is employed. In this case, the diaphragm must be anchored around the periphery of the valve seating, the effective area of the diaphragm is somewhat greater than the minimal area A of the valve seating itself. Consequently, the initial force required to close the valve is high since if the additional area of the diaphragm is ΔΑ then the initial force required to close such a valve is P.(A + ΔΑ).

However, as the valve is closed, the effect of the peripheral area of the diaphragm diminishes until the point when the diaphragm is sealingly engaged with the valve seating, whereupon the area of the diaphragm to which pressure is applied is exactly equal to A being the area of the valve seating. At this point, the force required to maintain the valve closed is exactly equal to the product of P.A as shown in the upper curve D.

In contrast, a piston valve always "sees" a cross-sectional area equal to A and, therefore, a constant force equal to P.A is required to close a piston valve as shown by the straight line P. - 10 - 107447/2 The lower curve designated I in Fig. 4a relates to the invention.

When the valve is fully open, pressure P is uniformly applied to the whole of the lower surface of the diaphragm 13 and, consequently, the force which is applied to the abutment member 17, tending to maintain the valve open, is exactly counter-balanced by the closing force applied to the abutment member 19. Consequently, the force which must be applied to the toggle member 15 in order to urge the abutment member 17 downwards so as to close the valve is initially zero. As the valve closes, the situation is as shown in the intermediate position of the valve in Fig. 3. In this position, the pressure of the fluid applied to the abutment member 17 increases relative to that applied to the abutment member 19 because the effective opening into the housing shown by arrow F decreases as the valve closes and, therefore, by Pascal's principle the pressure distribution will be in inverse proportion to the cross-sectional area. Consequently, an increasing force must steadily be applied to the toggle member 15 until the valve is finally closed, whereupon the closure force required to maintain the valve closed is exactly equal to the product of P.A.

It will thus be appreciated that the maximum closure force associated with a conventional diaphragm valve is greater than that required by either a piston valve or by a diaphragm valve according to the invention. Furthermore, whilst it is true that the maximum closure force required by the valve shown in Fig. 1 is exactly equal to that of a conventional piston valve, the actual energy required to close the respective valves is equal to the respective areas under the curves P and I shown in Fig. 4a. From this, it can be qualitatively determined that the overall energy required to close the valve shown in Fig. 1 is a little more than 50% of the overall energy required to close a conventional piston valve. Since the power rating of the motor which is used to rotate the toggle member 15 into the closed position is a function of the total energy requirement, it will thus be understood that - 11 - 107447/2 a motor having a lower power rating may be used to close the valve shown in Fig. 1 than would be necessary to close an equivalent piston valve.

When fluid flows in the opposite direction through the valve as in the situation shown in Fig. 2 of the drawings, then again when the valve is fully open pressure P is applied equally to both of the abutment members 17 and 19 since the toggle member 15 is balanced and the area of the diaphragm underneath each of the abutment members is equal. However, when the valve starts to close, the fluid pressure P is applied to the complete area of the diaphragm underneath the abutment member 19 but to a steadily diminishing area of the diaphragm underneath the abutment member 17 until, when the valve is fully closed, a net differential force equal to the product of P.A is applied to the abutment member 19 so as to maintain the valve closed. In such a configuration, as the toggle member 15 is rotated in a counter-clockwise direction so as to close the valve, the fluid pressure P applied to the abutment member 19 itself closes the valve and no force is therefore required by the motor which is coupled to the toggle member 15. This is shown in Fig. 4b by the curve designated I which represents the closure force required by the motor (shown in Fig. 5) in order to close the valve. It will thus be seen that the closure force commences at zero and actually decreases from zero to a value equal to - PA.

The curve marked P shows the equivalent situation when a piston valve is used. In this case, the initial closing force is equal to P.A equal to the pressure P of the fluid acting on the piston multiplied by the cross-sectional area A of the valve seating. However, when the valve is fully closed, no fluid acts on the piston and the effective fluid pressure is therefore now equal to zero. Thus, as shown in Fig. 4b, the closure force required for a piston valve equivalent to the arrangement shown in Fig. 2 decreases from an initial value of P.A to zero. - 12 - 107447/2 When a conventional diaphragm valve is employed, then the initial closure force is again equal to Ρ(Α+ΔΑ) and this also decreases until the valve is fully closed. In this situation, the peripheral area ΔΑ of the diaphragm surrounding the now closed valve seating is still subject to a pressure of P and, consequently, a net residual closure force equal to Ρ.ΔΑ is still required by the motor in order to maintain the valve closed as shown by the curve D in Fig. 4b.

Figs. 5 and 6 show sectional and perspective views of the operating mechanism according to the invention within a change-over valve, a detail 20 of which is illustrated having first and second fluid inlets 24 and 21 depending from corresponding valve seatings 22. and 23.

Disposed above the valve seatings 22 and 23 is a flexible diaphragm 25 operated on within corresponding areas of the fluid inlets 24 and 21 by respective abutment members 26 and 27 which are reciprocally depressed by a balanced toggle member 28 free to perform limited rotation . about a pivot axis 29 thereof.

In the situation shown in Fig. 5, a first end 30 of the toggle member 28 pushes the abutment member 26 against the diaphragm 25, thereby distorting the diaphragm 25 so that it covers the valve seating 22 and seals the fluid inlet 24. Whilst this obtains, the diaphragm 25 is clear of the valve seating 23, thereby allowing fluid to flow through the inlet passage 21 into the valve (or vice versa).

On the other hand, when the toggle member 28 is rotated about its pivot axis 29 in a clockwise direction, the pressure of the fluid in the fluid inlet 24, acting on the underside of the diaphragm 25 and hence on the abutment member 26, allows the diaphragm 25 to lift off the valve seating 22, thereby allowing fluid to flow once more through the fluid inlet passage 24. As the toggle member 28 is rotated further, the second end 31 thereof - 13 - 107447/2 forces the abutment member 27 against the diaphragm 25 in the vicinity of the valve seating 23, so as to seal the second inlet passage 21.

Referring to Fig. 6 of the drawings, there is shown a detail of a transmission system depicted generally as 35, for coupling an electric motor 36 to the toggle member 28 so as to rotate the toggle member 28 about its pivot axis 29. The transmission system 35 comprises a small diameter gear wheel 37 mounted on a shaft 38 of the motor 36, for engaging a relatively large gear wheel 39 adapted for rotation about a central pivot axis 40 supported between end bearings 41 (only one of which is visible in the figure).

The gear wheel 39 is provided in a periphery thereof with an arcuate slot 42 having opposing ends 43 and 44. The toggle member 28 is provided on either side of the pivot axis 29 with an upwardly depending armature 45 and 46 defining therebetween a substantially U-shaped hollow 47 in which there is disposed a cylindrical boss 48 eccentrically mounted on a first end 49 of a crank 50, having a second end 51 disposed within the arcuate slot 42.

Consequently, as the gear wheel 39 rotates, one end 43 or 44 of the arcuate slot 42 (depending on the direction of rotation of the gear wheel 39) impinges on the second end 51 of the crank 50, thereby rotating the crank and with it the cylindrical boss 48. Owing to the eccentric rotation 48 of the latter, there is imposed a lateral force on the inside surface of one of the armatures 45 or 46, thereby rotating the toggle member 28 about its pivot axis 29.

Upon completion of a closing or opening operation, the corresponding end 43 or 44 of the arcuate slot 42 remains in contact with the second end 51 of the crank 50. The state of the valve may now be altered by rotating the motor shaft 38 in the opposite direction. During an initial rotation of the motor shaft 38, the gear wheel 39 will start to rotate at - 14 - -107447/1 relatively slow speed (compared with the rate of rotation of the motor shaft 38) but at high torque owing to the gear ratio between the two gear wheels 37 and 39, there being no force imposed upon the second end 51 of the crank 50 until the remote end of the arcuate slot 42 contacts the second end 51 of the crank 50 on its opposite side. By the time this happens, the motor 36 will have reached full speed and a significant kinetic energy will be applied to the gear wheel 39. Consequently, an impulse is applied to the crank 50, causing it to rotate very quickly and nearly instantaneously to change the state of the toggle member 28.

' Figs. 7a, 7b and 7c show schematically a detail of the toggle member 28 when the valve 20 partially illustrated in Figs. 5 and 6 is in an intermediate, open and closed position, respectively. In the intermediate position shown in Fig. 7a, the axis joining the center of the cylindrical boss 48 to the first end 49 of the crank 50 passes through the pivot axis 29 of the toggle member 28. In this situation, any natural tendency for the toggle member 28 to rotate in either direction, imparts a turning moment to the toggle member 28 since the turning axis of the toggle member 28, corresponding to the first end 49 of the crank, is displaced from the point of contact of the armatures 45 and 46 of the toggle member 28.

In the open position shown in Fig. 7b, the armature 46 imparts a force to the cylindrical boss 48 passing through the first end 49 of the crank 50. Likewise, in the closed position shown in Fig. 7c, the armature 45 imparts a force to the cylindrical boss 48 passing through the first end 49 of the crank 50. In either of these situations, any tendency for the toggle member 28 to counter rotate so as to close or open the valve 1, respectively, is prevented because the only force acting on the cylindrical boss 48 acts through the first end 49 of the crank about which the cylindrical boss rotates. - 15 - 107447/1 Referring now to Fig. 8, it is seen that the toggle member 28 further includes a pair of resiliently biased leaf spring members 55 within the U-shaped hollow 47 such that an initial rotation of the motor depresses the cylindrical boss 48 against one of the leaf spring members 55 thereby rotating the toggle member 28 into the first or second position. Continued rotation of the motor causes the cylindrical boss 48 to depress the leaf spring member 55 whilst not imparting any further rotation to the toggle member 28. In such an arrangement, the toggle member 28 is at least partially formed of molded plastics, the leaf springs 55 being also formed of plastics and riveted to respective internal surfaces of the armatures 45 and 46.

Fig. 9 shows schematically an alternative embodiment of the operating mechanism for use with the valve 1 having a single valve seating 11 depending from which there is a fluid inlet 12. An unbalanced toggle member 56 is provided having first and second ends 57 and 58, respectively for imparting a force to a rubber diaphragm 13, or for receiving a force applied thereby, via corresponding first and second abutment members 59 and 60. A pivot axis 61 of the toggle member 56 is not at its center, the distance from the first end 57 to the center 61 being twice the distance from the second end 58 thereto. Fluid is continuously applied at a pressure P through a fluid inlet 62 which remains permanently open, so as to apply a pressure P on to the diaphragm 13 and thereby on to the abutment member 60.

With the valve open, a pressure P is applied to the lower surfaces of both abutment members 59 and 60. If the toggle member 56 were balanced (as shown in Figs. 1 and 2), then equal torques proportional to P.A would be applied to the toggle member, the constant of proportionality being the length ½L of the lever arm between the pivot axis 61 and the abutment members 59 and 60. The torque thereby required to close the valve would be negligible whilst to open the valve, a torque equal to ½P.A.L would be - 16 - 107447/1 required, where P is the fluid pressure, A is the cross-sectional area of the abutment members and L is the total combined length of the two lever arms between the first and second ends 57 and 58 of the toggle member 56.

However, with the unbalanced toggle member 56 shown in Fig. 9, when the valve is open, the torque applied to toggle member 56 by the abutment member 59 is twice that which is applied by the abutment member 60, owing to the relationship between the two lever arms. In effect, there is therefore applied a constant net opening torque equal to ½P.A.L which must be overcome in order to close the valve. There is thus required a net closing torque of ½P.A.L which must be applied to the toggle member 56 so as to close the valve. Once the valve is closed, however, the fluid pressure P is no longer applied to the abutment member 59 and thus the only torque acting on the toggle member 56 is the closing torque ½P.A.L which must be completely overcome by applying a counter torque of equal magnitude to the toggle member 56.

It will thus be seen by comparing the two situations for a balanced and unbalanced toggle member 56 having an equal length L, that for the unbalanced toggle member the opening and closing torques are both smaller than the opening torque required for the balanced toggle member. It is, of course, true that the closing torque required for the balanced toggle member is negligible, but since the size of the motor which is required to rotate the toggle member is dependent on the maximum required torque, this means that a smaller, less powerful, motor can be employed for the unbalanced toggle member.

Whilst the features of the operating mechanism described above with reference to Figs. 1 to 9 of the drawings are of universal application, it is particularly desirable to incorporate these features within a valve such as is typically connected in the water inlet feed of a garden sprinkler and - 17 - 107447/1 wherein there is provided the further improvement that an electrical motor is provided for effecting opening and closure.

All of the previous Figures showing operation of the toggle member, be it balanced as in Figs. 1 and 2 or unbalanced as in Fig. 9, relate only to the manner in which the inlet or outlet, as the case may be, of the operating mechanism is closed by the diaphragm under operation of the toggle member.

Figs. 10 to 13 show various cross-sectional views of a water valve designated generally as 70 which is controlled by means of a diaphragm-operated operating mechanism according to the principles of the invention.

The valve 70 comprises a main inlet pipe 71 having an internally threaded end piece 72 for threadably attaching thereto a water inlet feed pipe. Similarly, an outlet 73 having an internally threaded end piece 74 permits connection thereto of a water outlet pipe. Although the valve 70 is shown in some significant detail, it will be readily appreciated that the valve itself is well known in the art and it is shown by way of illustration only in order to put the invention into perspective. Thus, those detailed components of the valve which are not essential to the invention itself will not be described in further detail.

The water inlet 71 and water outlet 73 present an annular valve seating 75 which, as shown in Fig. 10, is plugged by a seal 76 having a generally trapezoidal cross-section and being free to move vertically up and down, depending on the relative pressure on opposite surfaces thereof, under the restraint of a peripheral diaphragm 77. As will further be seen from Fig. 10, part of the water inlet 71 extends above the diaphragm 77 so as to produce a cylindrical control chamber 78 whose base is the upper surface of the seal 76 and whose top and side portions are formed by a valve casing 79 being formed of molded plastics. - 18 - 107447/1 Extending outwardly from a side of the valve control chamber 78 is a cylindrical tube 80, depending downwardly from which is a generally T-shaped connection which, at opposite ends thereof, has two downwardly extending tubes 81 and 82 (see Fig. 11) which, respectively, adjoin the water inlet 71 and the water outlet 73 so as to be subjected to the water inlet pressure and the water outlet pressure, respectively.

Also shown attached to a front of the tube 80 is a plug 83 which facilitates manufacture of the valve but is inconsequential to a proper understanding of its operation.

As shown more clearly in Fig. 11, the two tubes 81 and 82 connected, respectively, to the water inlet 71 and the water outlet 73 are alternately opened and closed by means of a flexible diaphragm 85 operated on by means of corresponding abutment member ends 86 and 87 under the control of a see-saw type rocker assembly 88 having internal springs 89 and being rotated by: means of an electric operating cam 90 all exactly as described in detail above with particular reference to Figs. 7a, 7b, 7c and 8 of the drawings. The rocker assembly 88 rotates about a pin 91 (constituting a pivot axis) as shown in Fig. 10. Likewise, the operating cam 90 is rotated about its own pivot axis 92 via a gear train 93 coupled to a motor 94. The motor 94 together with the rocker assembly 88 and its associated components are enclosed within a control chamber 95 having at a top extremity thereof a manually-rotatable override assembly 96 which protrudes through an aperture at the top of the valve housing 95, sealed by an "O"-ring 97 so that a downwardly depending protuberance 98 which is eccentrically fixed to a lower internal edge of the override assembly 96 resides within the gap 99 between the opposite internal surfaces of the rocker assembly 88.

Having described in detail the construction of the valve 70, its operation will now be explained.

- - In the situation shown in Figs. 10 and 11, the rocker assembly 88 is positioned such that the abutment member 86 forces the diaphragm 85 on to the tube 82 so as to cut off the control chamber 78 from the water outlet 73. At the same time, since the abutment member 86 ris lifted and the diaphragm 85 does not seal the tube 81, the latter connects the control chamber 78 to the water inlet Ί1. As a result, water flows in through the water inlet 71 around the annular lower surface of the main diaphragm 77 and fills the control chamber 78 from which it has no escape to the water outlet 73 on account of the tube 82 being closed. Therefore, water pressure builds up within the control chamber 78 and acts on the valve seal 76 so as to completely seal the valve seating 75. In this condition, as shown in Fig. 10, the water valve 70 is closed and no water flows from the water inlet 71 to the water outlet 73.

As shown in Figs. 12 and 13, when the status of the rocker assembly 88 is exchanged, then the abutment member 86 closes the diaphragm 85 on to the tube 81 thereby cutting off the water inlet 71 from the valve control chamber 78. At the same time, the armature pin 87 is lifted, thereby connecting the water control chamber 78 to the water outlet 73 via the now open tube 82.

As a result, water within the valve control chamber 78 (as shown in Fig. 10) now pours out of the water outlet 73 via the open tube 82 and water entering the water inlet 71 applies pressure around the periphery of the main diaphragm 77 so as to urge the valve seal 76 upward and thus open the valve 70, whereupon water pours freely from the water inlet 71 through to the water outlet 73. This continues to happen until the status of the rocker assembly 88 is again changed, whereby water pressure can again build up in the valve chamber 78 until it is uncompensated and forces the valve seal 76 down again so as to close the valve seating 75. - 20 - 107447/1 The manner in which the rocker assembly 88 is controlled by the electrical motor 94 has itself been described in detail above with particular reference to Figs. 3 and 4 as well as Figs. 7a, 7b and 8 of the drawings. Therefore its operation will not be repeated here.

However, for the sake of completeness, the operation of the override assembly 96 will now be explained. Rotation of the override assembly 96 between its two extremities forces the eccentrically mounted protuberance 98 to exert pressure against one or other of the inside surfaces of the rocker assembly 88 so as to force it to rotate about its pivot axis 92 into a corresponding position. Clearly, if the orientation of the override assembly 96 is such that the rocker assembly 88 would be disposed into the position already dictated by the cam 90, then the override assembly 96 has no effect. However, if in this situation the override assembly is rotated through 180°, the protuberance 98 exerts pressure to the opposite inside surface of the rocker assembly 88 causing the latter to rotate about its pivot axis 92 and thus change the state of the valve 70. Such movement is possible because, as explained in detail above with reference to Fig. 8 of the drawings, the cam 90 operates on the inside surface of the rocker assembly 88 via corresponding leaf springs. Thus, if the override assembly 96 is rotated into a position to override the effect of the cam 90, then the rocker assembly 88 will rotate with the result that the cam 90 will compress the leaf spring with which it makes contact. Thus, the override assembly 96 allows for manual override of the valve 70 in the event, for example, of a power failure which prevents automatic operation of the valve.

It will be appreciated that a simpler operating mechanism can be employed, albeit with less benefit, so as not to impart an impulse to the toggle member when it is desired to change its state. The gear ratio between the two gear wheels determines the velocity ratio of the transmission system and permits the size of the motor to be reduced. However, where size is not - 21 - 107447/1 at a premium, a larger motor could, if desired, be coupled directly to the shaft 40, in which case the second gear wheel 39 could be replaced by a pulley having an arcuate slot in a periphery thereof.

It will also be understood that the leaf spring members 55 can be formed of any suitable resilient material, such as metal for example, and riveted or otherwise secured to the armatures of the toggle member, as required.

Claims (16)

- 22 - 107447/1 CLAIMS:

1. A diaphragm valve comprising a valve casing; inlet and outlet ports of said casing; an inner wall surface of said casing; one of said ports opening into said wall surface and having a peripheral valve seating formed in said wall surface; a flexible diaphragm juxtaposed with respect to said wall surface; a toggle member mounted in said casing and rotatable about a pivot axis thereof between first and second positions; a pair of spaced apart abutment members forming part of or associated with said toggle member and adapted to bear on a first surface of said diaphragm with a first of said abutment members juxtaposed with respect to said valve seating, and externally actuated drive means for pivotally displacing said toggle member into opening and closing said one port; the arrangement being such that fluid pressure generated between said wall surface and spaced apart locations of a second and opposite surface of said diaphragm pivotally displaces said toggle member in opposite senses whereby displacement in one sense results in said first abutment member sealingly biasing said diaphragm against said valve sealing.

2. The valve according to Claim 1, wherein the outlet port opens into the wall surface of the casing and the inlet port is connected to a source of fluid pressure.

3. The valve according to Claim 1, wherein the inlet port opens into the wall surface of the casing and conveys fluid to the outlet port.

4. The valve according to Claim 1, including a first inlet port opening into the wall surface of the casing and a first outlet port and a second outlet port opening into the wall surface of the casing and a second inlet port, the first inlet port and the second outlet port having respective valve seatings at opposite ends of the toggle member so that when one of the valve seatings is sealed by the diaphragm the other valve seating is open, and vice versa. - 23 - 107447/1

5. The valve according to Claim 1, wherein the toggle member is balanced so that when the valve seating is open, an equal torque is applied to opposite ends of the toggle member.

6. The valve according to Claim 1, wherein the toggle member is unbalanced so that when : the valve seating is open, unequal torques are applied to opposite ends of the toggle member.

7. The valve according to Claim 1, wherein the drive means includes an electric motor.

8. The valve according to Claim 7, wherein the electric motor is configured to impart an impulse to the toggle member so as to rotate it about a pivot axis thereof and thereby move the toggle member from the first position to the second position, or vice versa.

9. The valve according to Claim 7, wherein the electric motor is coupled to the toggle, member via a transmission system having a high velocity ratio.

10. The valve according to Claim 9, wherein the transmission system comprises a first gear wheel connected to an axis of the electric motor and a second gear wheel having a greater number of teeth than the first gear wheel and being coupled to the pivot axis of the toggle member.

11. The valve according to Claim 10, wherein the transmission system further includes a crank coupled at a first end thereof to the pivot axis of the toggle member and having a second end disposed within an arcuate slot in a periphery of the second gear wheel, such that rotation of the second gear wheel causes one of opposing ends of the slot to impinge on the second end of the crank and apply an impulse thereto of sufficient magnitude to rotate the crank and thereby the toggle member to said first or second position. - 24 - 107447/1

12. The valve according to Claim 11, wherein: the toggle member is provided on either side of the pivot axis with an upwardly depending armature defining therebetween a substantially U-shaped hollow, and a cylindrical boss is eccentrically mounted on the first end of the crank, said cylindrical boss being disposed between the armatures of the toggle member and being dimensioned such that rotation of the crank imposes a lateral force on an inside surface of one of the armatures so as to rotate the toggle member about its pivot axis.

13. The valve according to Claim 12, wherein the electric motor is so configured that when the toggle member is in either the first or second position said lateral force acts through an axis of rotation of the cylindrical boss so that even if power to the motor is interrupted there is no tendency for counter rotation of the cylindrical boss.

14. The valve according to Claim 12, further including a pair of resiliently biased leaf spring members within said U-shaped hollow such that an initial rotation of the motor depresses the cylindrical boss against one of the leaf spring members thereby rotating the toggle member into the first or second position, whilst continued rotation of the motor causes the cylindrical boss to compress the leaf spring member.

15. The valve according to Claim 14, wherein the toggle member is at least partially formed of molded plastics.

16. The valve according to Claim 1, further including a manual override assembly coupled to the toggle member for rotating the toggle member into said first or second position regardless of the position of the drive means. For the Applicants, REINHOLD COHN AND PARTNERS 90484-2.spc/jjt/2f>. .19%