FIELD OF THE INVENTION

This invention relates to a hydraulic valve, and more particularly but not exclusively, to a hydraulic valve for large diameter pipes.

BACKGROUND TO THE INVENTION

Large diameter pipes are used in many applications, including conveying fluids over large distances. A problem with said large diameter pipes is that the large diameter, and consequent large inner area of a pipe, requires large forces on the sealing / closing member / plunger to open and close valves in such pipes.

The problem has been addressed by providing a large diameter valve including an actuator, in the form of a hydraulic cylinder, with multiple pistons coaxially aligned on a piston rod. A pressure difference is created over the pistons and as a result of the multiple pistons, the surface area, and the resultant force exerted by the pressure difference, is increased for each additional piston. The cylinder actuates a sealing member which engages a rim, in the form of a valve seat, at the inlet of a valve in the closed position. A problem with this type of large diameter valve is that relatively high static pressure is constantly exerted on the sealing member / closing plunger from the inlet while the valve is in the closed position. OBJECT OF THE INVENTION

It is an object of this invention to provide a hydraulic valve which, at least partially, alleviates some of the problems associated with the prior art. SUMMARY OF THE INVENTION

In accordance with this invention there is provided a hydraulic valve comprising:

- a valve body having an inlet, an outlet and a passage for conveying fluid between the inlet and outlet;

- the passage having an annular inlet; and

- a closure member having an annular wall for closing the annular inlet and movable between an open position wherein the annular inlet is open and a closed position wherein the annular wall closes the annular inlet.

The annular wall may be a cylindrical wall;

The closure member is movable between the open position and the closed position by an actuator in the form of a hydraulic cylinder.

The hydraulic cylinder may include a deflection member, the deflection member defining at least one opening therein to allow for pressure equalisation on either side of the deflection member. The hydraulic cylinder includes a piston in the cylinder. Alternatively, the hydraulic cylinder may include a diaphragm in the cylinder.

The piston or diaphragm divides the cylinder into two chambers.

The closure member is attached to the piston or diaphragm by a central axis.

The central axis may include a biasing means. The biasing means may be a spring.

The hydraulic cylinder further may include at least one bearing provided with sealing means. More preferably the hydraulic cylinder may include two bearings. Most preferably, the hydraulic cylinder may include three bearings. A plurality of bearing may also be provided for. The bearing or bearings may be attached to the central axis of the hydraulic cylinder by spokes. The sealing means may be cup seals.

The cylindrical wall is attached to the axis by spokes. The hydraulic valve allows fluid flow in both directions.

The hydraulic valve includes at least one bearing provided with sealing means in the form of cup seals.

The hydraulic valve may have a diameter ranging from 40 to 1200 mm. The hydraulic valve further may have a pressure rating from 1000 kPa to 4000 kPa. The hydraulic valve may be provided with an anti-cavitation member.

The anti-cavitation member may extend at least partially across the annular inlet. The anti-cavitation member may define openings therein, so as to direct fluid flow through the openings and facilitate pressure reduction and/or regulation in the valve.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below by way of example only and with reference to the drawings in which:

Figure 1 is a schematic sectional view of a prior art hydraulic valve;

Figure 2 is a schematic sectional view of a hydraulic valve according to a first embodiment of the invention showing a closure member in the closed position;

Figure 3 is a schematic sectional view of the hydraulic cylinder of Figure 2 showing the closure member in the open position; Figure 4 is a schematic cross sectional view of a cylinder and valve body;

Figure 5 is a schematic cross sectional view of a closure member;

Figure 6 is a schematic cross sectional view of the cylinder and valve body of figure 4 and the closure member of figure 5;

Figure 7 is a schematic longitudinal sectional view of a hydraulic valve according to a second embodiment of the invention showing a closure member in the closed position;

Figure 8 is a schematic longitudinal sectional view of a hydraulic valve according to a third embodiment of the invention showing a closure member in the closed position;

Figure 9 is a schematic cross sectional view of a hydraulic valve according to a fourth embodiment of the invention showing a closure member in the open position, and also showing the direction of fluid flow in a first direction;

Figure 10 is a schematic cross sectional view of the hydraulic valve of

Figure 9, showing the direction of fluid flow in a second direction;

Figure 1 1 is a schematic cross sectional view of the hydraulic valve according to a fifth embodiment of the invention showing a closure member in the closed position;

Figure 12 is a schematic cross sectional view of the hydraulic valve of

Figure 11 , showing the closure member in the open position;

Figure 13 is a schematic cross sectional view of the hydraulic valve according to a sixth embodiment of the invention showing a closure member in the closed position; and

Figure 14 is a schematic cross sectional view of the hydraulic valve of

Figure 13, showing the closure member in the open position.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference to the drawings, in which like features are indicated by like numerals, a hydraulic valve is generally indicated by reference numeral 1.

Figure 1 depicts a prior art valve. The prior art valve has a body with an inlet and an outlet. An actuator consisting of a two coaxial hydraulic cylinders is attached to a closure member in the form of a disc. The actuator moves the disc from the open position wherein the inlet in uncovered to a closed position wherein the inlet is covered by the disc. Multiple pistons are necessary to create sufficient closing force opposing the opening force and retain the disc in the closed position. When the disc closes the inlet, a force acts on the disc as a result of the pressure at the inlet. Pressure differences are created over the multiple pistons to create sufficient force to move the closure member to the closed position. A hydraulic valve according to the invention is shown in Figures 2 to 14, wherein Figures 2 to 3 show a first embodiment of the present invention and Figures 7 to 14 show alternative embodiments of the present invention.

The hydraulic valve 1 , as shown in Figures 1 and 2, includes a valve body 2 having an inlet 3, an outlet 4 and a passage 5 for conveying fluid between the inlet 3 and outlet 4. The passage has an annular inlet 6 and the valve includes a closure member 7. The closure member has an annular wall 8 for closing the annular inlet 6 and is movable between an open position wherein the annular inlet 6 is open and a closed position wherein the annular wall 8 closes the annular inlet 6.

An actuator 9 in the form of a hydraulic cylinder 9 is located in the valve body 2. The hydraulic cylinder 9 is suspended within the valve body 2 by rib-like spokes 10 extending from the valve body 2 to the hydraulic cylinder 9. A piston 11 mounted on an axis 12 divides the hydraulic cylinder 9 into two chambers (13 and 14), a chamber on the inlet side 13 and a chamber on the outlet side 14. The piston has two back to back cup seals. A first control channel 15 extends into the inlet side chamber 13 and a second control channel 16 extends into the outlet side chamber 14. The piston includes a central extrusion 17 extending towards the inlet side. The extrusion 17 abuts a seal 18 which seals off the inlet side chamber 13.

A pressure difference may be created over the piston 1 1 using control channels (1 5 and 16), wherein channel 15 is a low pressure (LP) outlet side and channel 16 is a high pressure (HP) inlet side. The area of the piston 11 , which is exposed to the pressure difference, is greater on the outlet side chamber 14 than on the inlet side chamber 13 because of the central extrusion 17. This causes the actuator 9 to be biased towards the closed position. In other words, it is easier to move the closure member 7 towards the inlet 3 than moving it away from the inlet 3.

The pressure difference may be created, for example, by installing a line 19 from the inlet HP 3 to the second control channel 16 and another line 20 from the LP outlet 4 to the first control channel 15. This utilises the normal drop in pressure which occurs over any hydraulic valve and creates a pressure difference wherein the actuator 9 is biased to move the closure member 7 towards the closed position. A manual or automatic release valve 21 for controlling the expulsion of fluid from the end 22 of the line 19 is added to the line 19. When the release valve 21 is opened so that fluid is expelled from the end 22, pressure in the line 19 drops and consequently pressure in the outlet side chamber 14 also drops. This biases the actuator to move the closure member 7 towards the open position. This, therefore, allows an operator or regulating pilot valve to actuate the movement of the valve 1 by controlling the amount of expelled fluid through the release valve 21 . The closure member 7 includes an annular or peripheral wall 8. In the current embodiment of the invention, the annular wall 8 is in the form of an open cylinder which is attached to a hub 23 by spokes. The closure member 7 is attached to the axis 12 of the actuator 9 through the hub 23 with a nut fastened to a threaded end. As a result of the closure member 7 being an open cylinder with spokes, fluid is free to flow through the closure member 7 in the axial direction. The closure member 7 is movable between an open position (wherein the annular inlet 6 is open and fluid can freely flow from the inlet 3 through the annular inlet 6 into the passage 5) and a closed position (wherein the annular wall 8 closes the annular inlet 6 and prevents fluid from entering the passage 5)

The projected area of the closure member 7 in the axial direction is smaller than the radial projected area of the annular wall 8 thereof. In the closed position, the relatively high inlet supply pressure has no opening force on the annular wall 8, as the inlet pressure is also present on the rear end annular wall 8. The projected area of the closure member 7 in the axial direction is also significantly smaller than the disc shaped closure member of the prior art, thereby resulting in smaller forces acting on the actuator 9 when the closure member 7 is in the closed position (Figure 2).

Further embodiments of the present invention are shown in Figures 7 to 14. In low inlet supply pressure applications, as illustrated in Figure 8, the available surface area could be insufficient to open the hydraulic valve 1 fully. In order to resolve this problem, the diameter of piston central extrusion 17 is enlarged. This will then provide additional surface area for effecting opening cycles.

In other applications in which an initial high static inlet supply pressure (against the closure member 7 in the closed position) drops to a very low dynamic supply pressure, as is commonly experienced in long gravity supply and pumping supply lines), the dynamic pressure as is fed into the outlet side chamber 14 via second control channel 16 for purposes of closing the closure member 7, could be further assisted by the addition of a biasing means in the form of a spring 24, as is illustrated in Figure 7. Should high flow velocities be encountered in an application, the annular wall 8 may cause undesired turbulence and vibration. For such reason, a deflection means 26 is installed onto the extension of the axis 12 as per Figure 7. The deflection member 26 will not form a water tight seal with the closure member 7, thereby permitting equalisation of the pressure on the deflection member 26. Special ports (openings) are provided in deflection member 26 in order to ensure pressure equilibrium between the two surfaces of the deflection member 26.

Figure 9 shows the operation of the hydraulic valve 1 in an open position, wherein the fluid flows in a first direction, namely from the inlet 3 to the outlet 4, by entering the annular inlet 6, followed by the passage 5 and then exiting the valve 1 via the outlet 4.

Figure 10 shows an alternative embodiment from the one above. In this application, where a very high pressure differential is experienced, the direction of fluid flow through the valve 1 is reversed. That is, the left hand opening (previously the inlet 3) is now used as the outlet 4 and vice versa. In the present application, the valve 1 will tend to remain stationary when in the closed position, with no pressure in the two chambers (13 and 14) and only a small closing force on the axis 12. Control channel 15 is used to pressurise chamber 13 with the available inlet supply pressure. This will then open the closure member 7 when the opposing closing force acting on the piston 1 1 in chamber 13 is simultaneously reduced by means of an external add-on pilot valve control circuit.

Should high differential pressures in the above "reverse flow" application be experiences across the valve 1 , which exceeds a ratio of 4:1 , an anti- cavitation member 28 will be utilised. Further, in applications of very high flow velocity and differential pressure conditions, a further bearing 30 (Figure 8), supported by spokes, is added to ensure the continued alignment of the entire actuator 9 and closure member 7.

It is, therefore, envisaged that the invention will provide a hydraulic valve 1 , which is simpler and more cost efficient than the prior art. It is further envisaged that the invention will provide a hydraulic valve 1 with reduced opening forces on large diameter valve inlets 3. This allows the use of a smaller diameter piston assembly. The smaller piston assembly allows for a more streamlined flow pattern over the actuator 9. The increased peripheral area also results in a lower frictional head loss.

The fluid, which could be either a liquid or a gas, is only permitted to flow around the outer surface of the hydraulic cylinder, i.e. in the passage 5 and not through the internal area, as is the case in respect of several prior art valves, e.g. Ainsworth sleeve type DAM outlet valves and Honeywell Braukman model D 06 F pressure reducing valves.

The result is that opening forces acting on the closure member 7, would now require far less opposing closing forces for purposes of countering said opening forces, so as to keep the closure member 7 closed. This, therefore, results in a substantially reduces actuator 9 size, which, in turn, results in a much smaller overall hydraulic valve 1.

In yet a further alternative embodiment of the present invention, as is shown in Figures 1 1 to 14, the hydraulic valve 1 is in the form of an oblique globe valve. The valve 1 includes a valve body 2 having an inlet 3, an outlet 4 and a passage 5 for conveying fluid between the inlet 3 and outlet 4. The passage also has an annular inlet 6 and the valve includes a closure member 7. The closure member has an annular wall 8 for closing the annular inlet 6 and is movable between an open position wherein the annular inlet 6 is open and a closed position wherein the annular wall 8 closes the annular inlet 6. An actuator 9 in the form of a hydraulic cylinder 9 is substantially located in the valve body 2, however, in the present embodiment of the invention, the actuator 9 is located to one side of the body 2, and is not in line with the body as in the previous embodiments. The actuator 9 is further placed at an angle relative to the valve body 2.

The valve body 2 consists of two sections, the first section substantially defining the passage 5 and the second section adapted to engage with the actuator 9. The first section of the body 2, now curves inwards towards the actuator 9, so as to form a flange pair 34, in order to define the annular inlet 6 between the body 2 (more specifically this flange pair) and the actuator 9. The actuator 9 is now no longer suspended within the valve body 2 by rib-like spokes 10 extending from the valve body 2 to the hydraulic cylinder 9 (as per previous embodiments), but is now attached to the valve body 2 by means of nut-and-bolt fasteners 36.

The actuator, in the form of a hydraulic cylinder 9, includes a piston 1 1 (as per Figures 1 1 and 12); however, the piston can alternatively be replaced with a diaphragm 32 (as per the Figures 13 and 14). The diaphragm 32 is a "rolling" diaphragm, whereby the annular wall 8 is moved between the fully closed and fully open positions. The diaphragm 32 or piston 1 mounted on the axis 12 also divides the hydraulic cylinder 9 into two chambers (13 and 14), a chamber on the passage side 3 and a chamber on the body side 14. As in previous embodiments, a first control channel extends into the passage side chamber and a second control channel extends into the body side chamber. The pressure regulation is the same as in previous embodiments.

In the present embodiment of the invention, the passage 5 is not defined around the hydraulic cylinder, but is defined substantially by the first section of the valve body 2, to a side of the actuator 9. Fluid will therefore flow from the inlet 3 and into the annular inlet 6. The fluid will then pass the annular inlet 6, flow past the actuator 9, whereafter it will exit the valve 1 via the outlet 4. The present invention therefore also finds application in reducing the size of diaphragm actuated control valves.

The invention is not limited to the precise details as described herein. For example, instead of the closure member having a cylindrical wall, a wall forming any closed shape, for example a square, hexagonal, octagonal or triangular wall, may be used. Further, the valve actuator assembly could also be fitted to a cast 90° angle Globe or Oblique Globe type valve body.