WO2009043086A1

WO2009043086A1 - Valve assembly

Info

Publication number: WO2009043086A1
Application number: PCT/AU2008/001443
Authority: WO
Inventors: Paul C G Bode
Original assignee: TROUPERDALE Pty Ltd
Current assignee: TROUPERDALE Pty Ltd
Priority date: 2007-09-30
Filing date: 2008-09-29
Publication date: 2009-04-09
Anticipated expiration: 2010-03-30

Abstract

A valve assembly comprising a valve body having aligned body apertures and a first valve disc contained within the valve body, wherein the first valve disc has a disc aperture. An actuator effects rotation of the first valve disc relative to the valve body and results in the valve assembly moving between an open position wherein the disc aperture is aligned with the body apertures to define a flow path and a closed position wherein the disc aperture is offset from the body apertures to restrict the flow path.

Description

VALVE ASSEMBLY FIELD OF THE INVENTION

The present invention relates to valve assemblies, and more particularly to a rotatable disc valve assembly.

BACKGROUND OF THE INVENTION

Valves to control the flow of a fluid through various types of conduits have been employed for many years to provide an essential element of control over the flow rate. The valve may be used to open, close or partially obstruct the flow path.

The valve must be strong enough to withstand the pressure of the fluid built up in the conduit when the valve is closed to flow and when open should provide a relatively unrestricted flow path. Examples of such valves are of the gate, ball, plug, glob, piston and butterfly variety. The fluid whose flow rate is being controlled by the valve will often be of a highly corrosive and/or abrasive nature. This results in frequent maintenance or complete replacement of the valve being necessary which is a considerable expense to the end user and typically involves inconvenient downtime for the particular operating system. Many fluid flow systems transport slurries such as pulp, being wood pulp in water, which can bring about relatively rapid deterioration of many of the current valve designs. This is unacceptable to the plant operator as an efficient slurry handling system is crucial to maintaining a high operating efficiency. A valve design which is simple and effective in operation and which can provide improved wear-resistance, particularly to these kinds of severe conditions, will allow maintenance and replacement time and costs to be minimised and so will afford significant savings to the end user.

OBJECT OF THE INVENTION The object of the invention is to overcome or at least alleviate one or more of the above problems and to provide a simple and effective valve design as a useful commercial alternative. SUMMARY OF THE INVENTION

In a first aspect, although it need not be the only or indeed the broadest form, the invention resides in a valve assembly comprising:

(a) a valve body having aligned body apertures; (b) a first valve disc contained within the valve body wherein the first valve disc has a disc aperture; and (c) an actuator to effect rotation of the first valve disc relative to the valve body, wherein rotation of the first valve disc results in the valve assembly moving between an open position wherein the disc aperture is aligned with the body apertures to define a flow path and a closed position wherein the disc aperture is offset from the body apertures to restrict the flow path.

Preferably, the valve assembly further comprises a second valve disc, also having a disc aperture, contained within the valve body. Suitably, rotation of the first and second valve discs results in the valve assembly moving between an open position wherein the disc apertures are aligned with the body apertures to define a flow path and a closed position wherein the disc apertures are offset from the body apertures to restrict the flow path. Typically, the first and second valve discs are rotated in opposite clockwise or counter clockwise directions.

The or each disc aperture is formed in an area being half or less than half of the or each valve disc surface.

Preferably, the valve body comprises a first body plate and a second body plate having aligned body apertures.

The first body plate and/or the second body plate may have a split or break such that at least half of the plate surface can be lifted or removed in relation to the rest of the valve body.

Suitably, the actuator is selected from the group consisting of pneumatic, hydraulic, mechanical or electro-mechanical actuators. Preferably, the actuator is a pinion gear drive or a worm drive. In one preferred embodiment the pinion gear drive is located within a gear channel formed between the first valve disc and the second valve disc. Suitably, the gear channel may be formed by a cut away portion at the circumference of the first valve disc and the second valve disc.

If required, the cut away portion may be formed in only a portion of the circumference of the first and second valve discs.

Typically, the gear channel comprises gear teeth provided along its edges.

The gear teeth may be provided along the edges of only a portion of the gear channel. The gear channel may comprise one or more channel blocks.

In one embodiment, a disc sleeve separates the or each valve disc from the first and second body plate.

In one preferred embodiment the invention resides in a valve assembly comprising: (a) a valve body comprising a first body plate and a second body plate having aligned body apertures; (b) a first valve disc and a second valve disc located within the valve body, wherein each of the first and second valve discs have a disc aperture; and (c) a pinion gear or worm drive to effect simultaneous and opposite clockwise or counter clockwise rotation of the first and second valve discs relative to one another, wherein rotation of the first and second valve discs results in the valve assembly moving between an open position wherein the disc apertures are aligned with the body apertures to define a flow path and a closed position wherein the disc apertures are offset from the body apertures to restrict the flow path

Further features of the present invention will become apparent from the following detailed description. Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

BRIEF DESCRIPTION OF THE FIGURES

In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the accompanying figures wherein:

FIG 1 shows an exploded perspective view of a valve assembly according to an embodiment of the invention;

FIG 2 shows a sectional side view of the apparatus shown in FIG 1 ; FIG 3 shows a more detailed view of part of the apparatus shown in FIG 2;

FIG 4 shows a plan view of another embodiment of the valve assembly of the invention;

FIG 5 shows a sectional side view of the apparatus shown in FIG 4; and FIG 6 shows a plan view of a valve assembly according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have developed a valve assembly, one embodiment of which is shown in FIG 1. Valve assembly 100 comprises a valve body which is made up of joined first and second body plates 111 and

112, respectively. The two body plates are held together by fasteners 113.

Both first and second body plates 111 and 112 contain body aperture

114 which are defined by flanges 115 which also serves to form a sealing abutment with the flow inlet or outlet conduit, as appropriate. In use, body apertures 114 of the first and second body plates 111 and 112 are completely aligned. Conduit fasteners 116 are provided around flanges 115 to fix the conduit in place.

First and second body plates 111 and 112, when joined together by plate fasteners 113, define, between their inner surfaces, a valve chamber. The valve chamber contains first valve disc 130 and second valve disc 131 having first and second disc apertures 134 and 135, respectively. Also located within this valve chamber is gear channel 119 having gear teeth 133 and first channel blocks 120.

Pinion gear 140 sits within gear channel 119. A drive shaft 141 links pinion gear 140 to handle 142.

FIG 2 shows a sectional side view of the apparatus shown in FIG 1 with the direction of the conduit flow path indicated with arrows.

First and second body plates 111 and 112 can be seen to have inner plate surfaces 122 and 123, respectively, which define between them the valve chamber. First valve disc 130 and second valve disc 131 are in abutment at their outer surfaces with inner plate surfaces 122 and 123, respectively, and also contact each other at valve contact surface 132.

Gear channel 119 and gear teeth 133 are shown as running the length of FIG 2 for the sake of convenience in visualising the actuating mechanism but if the section was through the first and second disc apertures 134 and 135 then the gear teeth 133 would not normally be visible in a section view of that area. FIG 2 shows valve assembly 100 in a position such that first and second disc apertures 134 and 135 are in complete alignment with the body apertures 114 in first and second body plates 111 and 112. In other words the valve assembly 100 is shown in the open position to define the flow path indicated by the arrows. Gear channel 119 is formed by a cut away portion around the circumference of first and second valve discs 130 and 131 , as indicated in FIG 1. Gear teeth 133 project into gear channel 119 from the surface of both first and second valve discs 130 and 131. Pinion gear 140 engages with gear teeth 133 and, when actuated, moves along the space between the opposing rows of gear teeth 133 in gear channel 119.

FIG 3 shows a more detailed view of part of the apparatus shown in FIG 2. Pinion gear 140 is seen to have pinion teeth 144 which engage with gear teeth 133. The central portion 143 of pinion gear 140 receives drive shaft 141 to connect pinion gear 140 to handle 142. For the sake of clarity neither drive shaft 141 nor handle 142 are shown in FIG 3. The vertical axis of pinion gear 140 is seen to sit over the line formed by valve contact surface 132 so each row of gear teeth 133 connected to first or second valve discs 130 and 131 is equidistant from pinion teeth 144.

As can be seen in FIG's 1 and 2, body apertures 114 are formed within an area being half or less than half of the surface of first and second body plates 111 and 112, as seen in the view show in FIG 1. Likewise, first and second disc apertures 134 and 135 are formed within an area being half or less than half of the surface area of the first and second valve discs 130 and 131. The remaining surface of the first and second body plates 111 and 112 and first and second valve discs 130 and 131 are made of a continuous non-porous material. The first and second body plates 111 and 112 are arranged such that the body apertures 114 are always in alignment and so, when valve assembly 100 is in use, any restriction to the flow path which is required must be provided by the relative position of first and second valve discs 130 and

131 and, hence, their corresponding first and second disc apertures 134 and 135.

The first and second body plates 111 and 112 are in sealing contact at their circumference and may held in this position in a number of ways such as by fasteners 113 which may take the form of rivets, screws, pins, clamps and the like. Alternatively, adhesives or a pressure fit may be employed. To ensure a sealing contact a gasket such as an O-ring or washer may be placed between the abutting portions of first and second body plates 111 and 112.

The first and second body plates 111 and 112 may be manufactured from a wide range of materials such as high density cross-linked polymers, fibre reinforced polymers, ceramics, stainless steel, carbon steel, duplex steels, titanium, tungsten carbide, hastelloy® and stellite®. Materials which are relatively resistant to abrasion, corrosion and high temperatures are preferred for durability.

The flow conduit, both inlet and outlet portions, can be attached to surround each body aperture 114 and contact flanges 115 which may have a gasket, as described for the valve body plates, to ensure a sealing contact. The flow conduits may be held in place by conduit fasteners 116, adhesives or a pressure clamp fit which may take a form such as described above in relation to fasteners 113.

FIG 2 shows how the first and second body plates 111 and 112 join at their outer ends and how flanges 115 are placed to receive the conduits. First and second body plates 111 and 112 may have a flat surface with an extension or lip as shown in FIG 2 or, alternatively, may present a curvature or be shaped in some way such that they make contact at their circumference. The area between the inner plate surfaces 122 and 123, being the valve chamber, contains first and second valve discs 130 and 131 as well as gear channel 119. First and second valve discs 130 and 131 are in low friction sealing contact with the inner plate surfaces 122 and 123. First and second valve discs 130 and 131 may be manufactured from a wide range of materials such as high density cross-linked polymers, fibre reinforced polymers, ceramics, stainless steel, carbon steel, duplex steels, titanium, tungsten carbide, hastelloy® and stellite®. Materials which are relatively resistant to abrasion, corrosion and high temperatures are preferred for durability.

The first and second valve discs 130 and 131 are in contact and form a sealing contact along valve contact surface 132. The surfaces of first and second valve discs 130 and 131 which form this contact surface should be made from or coated with a low friction material to enable the discs to freely rotate relative to one another.

The first and second valve discs 130 and 131 and/or the first and second body plates 111 and 112 may be dimensioned such that sufficient pressure is provided on the inner surfaces of the body plates by the valve discs and between the valve discs themselves to hold the valve discs in place and ensure the sealing contact of all components under typical valve operating conditions.

As described previously, a portion of the circumference of the inner surface of first and second valve discs 130 and 131 is cut away to leave a track. Gear teeth 133 project from this cut away track on each valve disc.

Any form of projection which may engage with the projections of a pinion gear or the like may be suitable for use in the present invention. Gear teeth 133 may be formed integrally from or affixed to the valve discs and may, therefore, be made from materials which are the same or different to those described as suitable for manufacture of the valve discs. Pinion gear 140 and a portion of drive shaft 141 can be seen, in FIG

1 , to extend into the valve chamber. A small portion of the first and second body plates 111 and 112 must, therefore be cut away to accommodate the drive shaft 141. The drive shaft can be surrounded by an O-ring or other suitable gasket to ensure the sealing engagement of the two body plates is not interrupted.

FIG 1 shows the body apertures 114 and first and second disc apertures 134 and 135 in complete alignment. This is achieved when the first and second valve discs 130 and 131 are rotated independently in a clockwise and counter clockwise direction using pinion gear 140. This rotation motion is indicated in FIG 3 where the pinion teeth 144 of pinion gear 140 are seen to intermesh simultaneously with gear teeth 133 of both the first and second valve discs 130 and 131. It will be appreciated that if the pinion gear 140 is turning in, for example, a clockwise direction then the engagement of the pinion teeth 144 with gear teeth 133 will be such that while first valve disc 130 is driven upwards (as described looking directly at FIG 3) second valve disc 131 is driven downwards. When applied to the orientation shown in FIG 1 this would mean that first valve disc 130 is driven in a counter clockwise direction while second valve disc 131 is driven in a clockwise direction. In one general embodiment the gear channel may be formed from a circular assembly composed of two equal parts. One part of the circular assembly forms half the gear channel and will be in some manner connected at the circumference of the first valve disc while the second part is connected at the circumference of the second valve disc. When the two parts of the circular assembly are in place at the circumference of the valve discs they come together to form the gear channel, operating as previously described.

The operation of one embodiment of valve assembly 100 in opening and closing a flow path will now be described. As described above, first and second disc apertures 134 and 135 are formed within an area being half of the surface area of the first and second valve discs 130 and 131 while the remaining surface of the first and second body plates 111 and 112 and first and second valve discs 130 and 131 are made of a continuous solid material. This means that when the valve disc apertures are not in alignment with the body apertures then the valve discs are presenting a solid continuous surface to the body apertures and so the valve assembly 100 is closed to flow. Starting from a closed position, in which the disc apertures 134 and

135 may be at 180 degrees to the body apertures or at least in a position such that there is no overlap between the two sets of apertures, handle 142 is turned in either a clockwise or counter clockwise direction. This in turn causes pinion gear 140 to rotate due to its engagement with drive shaft 141. As pinion gear 140 rotates, attached pinion teeth 144 engage with and apply a force to, gear teeth 133 on first and second valve discs 130 and 131. This brings about the simultaneous rotation of first and second valve discs 130 and 131 in opposite clockwise or counter clockwise directions.

This rotation causes the first and second disc apertures 134 and 135 to move in like opposite clockwise or counter clockwise directions until they simultaneously start to overlap with individual portions of body apertures 114. A flow path, however, is not defined until the disc apertures 134 and 135 then begin to align with one another. At first only a slim oval shape will be presented as an open flow path and fluid flow would still be severely restricted. Further rotation of the valve discs, however, will bring about an increasing degree of overlap and so an increasingly large flow path. Eventually, the two disc apertures will be in complete alignment with the body apertures and a fully open flow path is created.

Channel blocks 120 and 121 (not visible in FIG 1 ) may be provided to limit the extent of rotation of first and second valve discs 130 and 131. For example, starting from a closed position, in which disc apertures 134 and 135 may be at 180 degrees to the body apertures 114, the pinion gear will be in contact with a channel block which may simply take the form of a large gear tooth or any other structure such that pinion gear 140 is unable to engage it with pinion teeth 144. Handle 142 is then turned such that pinion gear 140 turns to drive the first and second valve discs 130 and 131 in a direction to move the channel block away from pinion gear 140.

This direction of rotation continues until the two disc apertures 134 and 135 are in complete alignment with the body apertures 114 and the flow path is therefore in the open position. At this point the pinion gear 140 will contact a second channel block (120 or 121) and further rotation in the original direction to begin restricting the flow path again will be prevented.

Handle 142 must then be turned the opposite way to restrict or close the flow path and so the valve disc's movement is brought about by cycling between the two channel blocks. It will be appreciated that those of skill in the art will understand that the channel blocks could take different forms and achieve the same result. For example, there could be one channel block on each valve disc, spaced approximately 180 degrees apart or there could be pairs of channel blocks on the valve discs which would be adjacent in the closed or open position.

FIG 1 shows a pair of channel blocks 120. The disc and body apertures are in complete alignment at this point and it can be seen that the individual channel blocks 120 will prevent further rotation if handle 142 is turned in a counter clockwise direction. A second pair of channel blocks 121 (not visible in FIG 1) would be provided in a similar manner approximately 180 degrees around the circumference of the valve discs from channel blocks 120. This would limit motion between the open and closed positions as described above.

It should be understood that the disc apertures, and so the valve discs, do not necessarily have to move approximately 180 degrees between the open or fully aligned position and the closed position. Any angle of rotation which results in the flow path being blocked is suitable for the closed position and, depending on the exact size and placement of the various apertures this may be less than or greater than 180 degrees. In an alternative embodiment, the channel blocks take the form of latches which can be activated by insertion of a key into a keyhole formed within the valve body plates 111 and 112. Turning the key activates the latch and the valve discs, and hence the disc apertures, are locked into their present position.

In a further embodiment, the channel blocks may take the form of external apertures provided on an extension of the valve discs. When the valve assembly is in the open and/or closed position these external apertures are aligned such that a simple locking mechanism, for example a padlock, may be passed through them. This will prevent any further rotation of the valve discs relative to one another (since they rotate in opposite directions) and so will keep the valve assembly locked in the desired position.

In yet a further alternative embodiment, channel blocks or latches are not employed at all and instead the gear teeth 133 are only provided on a portion of the circumference of first and second valve discs 130 and 131 instead of along the entire circumference, as indicated in FIG 1 , or the cut away area forming the gear channel is only provided along a suitable portion of the circumference of the first and second valve discs. The gear teeth 133 should still be sufficient and appropriately placed to allow the full range of necessary rotational motion to achieve the closed and open flow path positions as described but beyond this the teeth may simply not be provided and pinion gear 140 cannot engage beyond this area.

It should be understood that the interlocking pinion gear 140 and gear teeth 133 system described is not the only actuating means to achieve rotation of the first and second valve discs 130 and 131 in opposite clockwise or counter clockwise positions. Any form of ring gear transmission assembly may be suitable so long as it can engage the one or more valve discs and effectively transfer the rotational torque from the gear to said valve discs.

FIG 4 shows a plan view of another general embodiment of the valve assembly of the invention wherein a worm drive is employed to effect rotation of the first and second valve discs 130 and 131. Worm 150 can be seen to sit in a portion of gear channel 119 and can be turned by handle 151. The mechanics of a worm drive are well known to a person of skill in the art and will not be described in detail here.

FIG 5 shows a sectional side view of the apparatus shown in FIG 4. Briefly, worm 150, which may take the form of a threaded screw, sits inside gear channel 119 within the valve chamber and runs parallel to the first and second valve discs 130 and 131. Its threads engage with teeth provided on first and second worm gears 152 and 153 which in turn engage first and second valve discs 130 and 131 , respectively, via worm teeth 154.

Turning worm handle 151 causes worm 150 to rotate and turn worm gears 152 and 153 via engagement with the worm teeth provided thereon.

As worm gears 152 and 153 turn, worm teeth 154 engage with gear teeth

133, previously described, and result in first and second valve discs 130 and

131 being rotated in opposite clockwise or counter clockwise directions.

In one embodiment, a worm drive as described above may be provided at both the top and bottom of the valve assembly (as shown in FIG 5) to rotate the valve discs in the forward and reverse directions or, alternatively, one reversible worm drive is employed.

Actuating means other than a handle which has to be manually turned are considered within the scope of the present invention. A person of skill in the art would understand, in light of the present disclosure that other actuators such as pneumatic, hydraulic and electro-mechanical actuators could be used to effect rotation of the valve disc(s) relative to the valve body.

One non-limiting example of a further type of actuator would be the use of a shutter bar type arrangement instead of the handle to drive shaft and pinion gear arrangement. This involves a shutter bar extending outwardly from the periphery of one of the valve discs. The shutter bar may be fixed to the valve disc or may be formed integrally and is accommodated within the valve assembly by an appropriate cut away portion of the valve body. In one embodiment this cut away portion of the valve body forms a circumferential slot in one valve body plate through which the shutter bar moves.

As the shutter bar is moved, either manually or indirectly through a further actuator, the valve disc is caused to rotate in a like clockwise or counter clockwise direction thereby causing the flow path to become open or closed in the manner previously described.

If there are two valve discs within the valve assembly then a cog or gear may be placed between the two situated within a gear channel and engaging teeth attached to both valve discs as previously discussed. The movement of the shutter bar and hence the attached valve disc would cause the cog or gear to move and this in turn would bring about simultaneous opposite clockwise or counter clockwise motion of the other valve disc. The shutter bar may be locked into place in either the open or closed valve assembly positions. Such an arrangement may be appropriate in low pressure flow conduit applications where a direct manual action is preferred.

Whatever particular actuating means is employed it will be understood that in one embodiment the invention resides in a valve assembly comprising:

(a) a valve body having aligned body apertures;

(b) a first valve disc contained within the valve body wherein the first valve disc has a disc aperture rotatable between an open and closed position; (c) an actuator to effect rotation of the first valve disc between an open position wherein the disc aperture is aligned with the body apertures and a closed position wherein the disc aperture is not in alignment with the body apertures.

In a preferred embodiment the valve assembly comprises a second valve disc contained within the valve body and having a disc aperture rotatable between an open and closed position. The actuator will effect rotation of both the first and second valve discs, simultaneously in an opposite clockwise or counter clockwise, between an open position wherein the disc apertures are aligned with each other and with the body apertures and a closed position wherein the disc apertures are not in alignment with each other and with the body apertures.

In the general embodiment shown in FIG 5 a first disc sleeve 160 is located between first body plate 111 and first valve disc 130 and a second disc sleeve 161 is located between second body plate 112 and second valve disc 131. These disc sleeves 160 and 161 will be made of a material that results in a low friction contact surface being formed between the valve body plates and the valve discs. This helps to ensure smooth and unrestricted rotation of the valve discs. Disc sleeves may be manufactured from high density cross linked polymers, stainless steels, ceramics, fibre reinforced polymers and the like. The use of disc sleeves is particularly beneficial when the materials chosen for construction of the valve body plates and valve discs would be likely to provide significant resistance to rotation of the valve discs.

The disc sleeves must not interfere with the alignment of the disc apertures and body apertures and so, in one embodiment, the disc sleeves are fixed i.e. they do not rotate relative to the body apertures and each disc sleeve is provided with an aperture which is in complete alignment with the body apertures. In an alternate embodiment the disc sleeves are connected such that they have apertures which are in complete alignment with the disc apertures and they rotate in a synchronised manner with the valve discs to ensure this alignment is maintained at all times. Alternatively, any of the valve contact surfaces, such as the body plates, valve discs or disc sleeves may be treated with a low friction surface coating using techniques including but not limited to filtered arc deposition (FAD), plasma activated chemical vapour deposition (PACVD), hybrid physical and chemical vapour deposition (PVD-CVD) to provide one or more low friction and highly wear resistant surfaces. This can aid in improved operation and increased lifetime of components.

Although the discussion up to this point has involved the use of apertures with a generally circular cross-sectional shape for both body and disc apertures it will be appreciated that other shapes and designs of apertures are considered appropriate. In principle, any shape of aperture which can connect with the conduit to provide good flow characteristics may be suitable. The shape of the actual flow conduit may, therefore, determine the shape of the various apertures.

In the embodiment shown in FIG 6, for example, the body apertures 114 are still generally circular in cross-sectional shape but the disc apertures have additional cut away portions 117 and 118. First body plate 111 is not shown in FIG 6, other than flange 115 and body aperture 114, so as to enable the valve disc apertures to be better visualised. The main portion of the disc apertures is still circular but the first valve disc 130 has a triangular- like cut away portion 117 (extending leftwards when looking at FIG 6) indicated by a solid line. Second valve disc 131 has a similar shape but with the thangular-like cut away 118 placed on the opposite (rightward extending) side of the circle so that the two disc apertures 134 and 135 are mirror images of each other. Since the second disc aperture cut away portion 118 would not strictly be visible in FIG 6 it has been indicated as a broken line. Solid arrows indicate how the disc apertures rotate in opposite clockwise and counter clockwise directions to then at least partly align between body apertures 114.

When the valve assembly is in the open position the circular portion of the two disc apertures will overlap and be completely aligned while the two triangular-like cut aways 117 and 118 extend out from the circular portion as indicated in FIG 6. This results in the total flow path size provided by the disc apertures being greater than that provided by the body apertures. This allows for fine control over and improvement of the flow characteristics of fluid through the valve assembly. This can result in less turbulence through the valve assembly which is particularly important in operating conditions of high fluid flow rates and/or the flow of highly abrasive or corrosive fluids.

A number of other shapes for the disc and/or body apertures can be contemplated in light of the present disclosure to improve the flow characteristics of fluid through the valve assembly. In one embodiment wherein both disc and body apertures are circular it can be beneficial to simply have the disc apertures of greater diameter than the body apertures.

It should be appreciated that although the embodiments discussed employ two valve discs (130 and 131) it is within the scope of the present invention to only use one valve disc. The valve assembly would operate in essentially the same manner as already described except for appropriate modifications to the pinion gear drive, worm drive or the like to only drive the rotation of one valve disc. Switching between the open and closed position would still involve overlap of the disc aperture with the body apertures with the difference being that as soon as the apertures overlap to any extent then the flow path is at least partially open. This means that, depending on whether the valve disc is rotated clockwise or counterclockwise, the flow will begin in an area biased towards one side or the other of the conduit. Although this design of using one valve disc will work adequately it is preferred to employ two valve discs as previously described. This is because the opposite rotation of the disc apertures results in the flow path becoming open only when the two disc apertures overlap which must occur in a centrally located position within the conduit/potential flow path. This provides advantages in improving the flow characteristics at all stages of opening the flow path. As discussed above this is particularly important in high flow and abrasive/corrosive media flow conditions as it results in less damage to the valve assembly and therefore maintenance and replacement costs are avoided or at least substantially delayed compared to other valves. Discussion thus far has also centred on embodiments of the valve body where there is a separate first and second body plate provided which are fastened or held together in some manner. It will be appreciated that the valve body plates may be integral, such as having been cut out of one piece of material and be hinged in some manner at one point to allow them to be opened and closed for insertion of the necessary working components. Thus discussion of a first and second body plate, as described herein, relates only to the fact that one portion of the body plate will be substantially adjacent the first valve disc and a second portion of the body plate will be substantially adjacent the second valve disc and does not limit the valve assembly to having two separate body plates.

In a further embodiment of the present invention, either or both of the body plates may be provided with a split or break along a central horizontal axis thereof. This may be held in place by means of a catch or latch and can be lifted or removed as desired to allow access to the internal components of the valve assembly. This means maintenance, such as removal of the worm or worm gear, can be carried out while the valve assembly is still connected in-line with the flow path. The portion of the body plate which can be lifted or removed will form a sealing contact with the rest of the body plate when put back into place.

Therefore, in one aspect, the includes a method of repairing leaks without complete disassembly of the valve or removal from the conduit including the steps of (a) providing the valve assembly with a split or break; and (b) removing the valve discs, gear assembly or other components requiring repair or replacement. So long as one valve disc remains misaligned with the valve body apertures or an insert can be added to achieve the same effect then the flow can be prevented while maintenance takes place.

The valve assembly provided by the present invention will be useful for a range of applications in the flow control of many fluids including but not limited to aqueous solutions, oils, slurries, corrosive fluids, chemical vapours, particulate gas streams and steam. Its design is particularly suitable to use in controlling slurry streams which can be extremely abrasive and corrosive to many current valve designs resulting in costly maintenance, replacement and operational downtime for the user. The present valve assembly, by its particular design, is better able to withstand these conditions to minimise the need for maintenance, replacement or operational downtime. This is particularly so when the fluid flow within the conduit contains highly abrasive materials due to the characteristics of the flow stream generated, as previously described.

Further, the valve assembly as described herein is a highly modular design and is capable of being adapted to accommodate several different material selections for different valve components.

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention.

Claims

1. A valve assembly comprising:

2. The valve assembly of claim 1 further comprising a second valve disc, having a disc aperture, contained within the valve body.

3. The valve assembly of claim 2 wherein rotation of the first and second valve discs results in the valve assembly moving between an open position wherein the disc apertures are aligned with the body apertures to define a flow path and a closed position wherein the disc apertures are offset from the body apertures to restrict the flow path.

4. The valve assembly of claim 3 wherein the first and second valve discs are rotated in opposite clockwise or counter clockwise directions.

5. The valve assembly according to any one of the preceding claims wherein the or each disc aperture is larger than the body apertures.

6. The valve assembly of claim 1 or claim 2 wherein the or each disc aperture is formed in an area being half or less than half of the or each valve disc surface.

7. The valve assembly of claim 1 or claim 2 wherein the or each disc aperture has a circular cross-sectional shape.

8. The valve assembly of claim 7 wherein the or each disc aperture has a circular cross-sectional shape with an additional cut away portion.

9. The valve assembly of claim 1 or claim 2 wherein the or each valve disc is manufactured from high density cross-linked polymer, ceramic, stainless steel, carbon steel, duplex steel, titanium, tungsten carbide, nickel alloy or cobalt-chromium alloy.

10. The valve assembly of claim 1 or claim 2 wherein the valve body comprises a first body plate and a second body plate having aligned body apertures.

11. The valve assembly of claim 1 or claim 10 wherein the body apertures are circular.

12. The valve assembly of claim 11 wherein the first body plate and/or the second body plate has a split or break such that at least half of the plate surface can be lifted or removed in relation to the rest of the valve body.

13. The valve assembly of claim 1 wherein the valve body is manufactured from high density cross-linked polymer, ceramic, stainless steel, carbon steel, duplex steel, titanium, tungsten carbide, nickel alloy or cobalt-chromium alloy.

14. The valve assembly of claim 1 or claim 2 wherein the actuator is selected from the group consisting of pneumatic, hydraulic, mechanical or electro-mechanical actuators.

15. The valve assembly of claim 14 wherein the actuator is a pinion gear drive or a worm drive.

16. The valve assembly of claim 15 wherein the pinion gear drive is located within a gear channel formed between the first valve disc and the second valve disc.

17. The valve assembly of claim 16 wherein the gear channel is formed by a cut away portion at the circumference of the first valve disc and the second valve disc.

18. The valve assembly of claim 17 wherein the cut away portion is formed in only a portion of the circumference of the first and second valve discs.

19. The valve assembly of claim 16 and claim 17 wherein the gear channel comprises gear teeth provided along the circumference of the first and second valve discs.

20. The valve assembly of claim 19 wherein the gear teeth are provided along the only a portion of the circumference of the first and second valve discs.

21. The valve assembly of claim 16 wherein the gear channel further comprises one or more channel blocks.

22. The valve assembly of claim 10 further comprising a disc sleeve separating the or each valve disc from the first and second body plate.

23. The valve assembly of claim 22 wherein the disc sleeve is manufactured from or coated with a low friction material.

24. The valve assembly of claim 1 or claim 3 wherein the flow path is suitable for the passage of aqueous solutions, oils, slurries, corrosive fluids, chemical vapours, particulate gas streams and steam.

25. A valve assembly comprising:

(a) a valve body comprising a first body plate and a second body plate having aligned body apertures;

(b) a first valve disc and a second valve disc located within the valve body, wherein each of the first and second valve discs have a disc aperture; and

(c) a pinion gear or worm drive to effect simultaneous and opposite clockwise or counter clockwise rotation of the first and second valve discs relative to one another, wherein rotation of the first and second valve discs results in the valve assembly moving between an open position wherein the disc apertures are aligned with the body apertures to define a flow path and a closed position wherein the disc apertures are offset from the body apertures to restrict the flow path.