The invention relates to a conduit that includes means for sealing an axial gap between components of conduit .

Background

The control of a fluid passing along a conduit is usually by means of a valve. A valve comprises a moveable member whose position is adjusted to adjust the free passage of flow along the conduit.

The invention is particularly but not exclusively relevant to a form of valve used to regulate the flow of water of water passing along a drain as described in WO 2009/136200 (Hymetrics), "Method and Apparatus for

Diverting Flowing Water from a Conduit". This describes a conduit with a rotatable section between upstream and downstream fixed sections of the conduit, and with seals to prevent leakage. The conduit is of circular cross- section. The rotatable section includes an aperture whose circumferential position is varied by rotation about the axis of the conduit to allow the elevation of the

aperture to be varied and thereby allow a variable portion of the flow in the drain to discharge through the aperture. This type of apparatus is designed to control the flow of water in drains and sewers.

One approach to sealing a circumferential gap is to use lip-seals or O-rings. These require precise

dimensions between the fixed and rotating parts to ensure the gap is always within the mechanical tolerances of the seal. This precision is costly to achieve, particularly for apparatus of large diameter. Furthermore, the flow in drains carries grit and other debris. This tends to collect in the grooves that house lip-seals or O-rings and thereby impede the effectiveness of the seal by limiting its elastic range or destroying the material of the seal by abrasion. This invention does not make use of lip-seals or 0- rings. Instead, it relates to the application of rings of compression packing. Compression packings are typically woven to form square cross-section of a composite fibre over an elastic core. The fibres may for example be tightly woven cross-plait of aramid fibres and

PTFE/graphite yarn to provide an abrasion-resistant low friction seal with good compression/recovery capable of sealing across out-of-true (low tolerance) gap

geometries. Such compression packings are flexible; cut lengths can be easily formed into rings to provide a circumferential seal.

Compression packings are compressed against the surfaces to be sealed. Pressure applied to one side of a packing is transmitted to all surfaces through the bulk elasticity of its core. Thus, a packing ring squeezed axially will exert radial and axial pressures on the confining surfaces of the space in which the packing is housed. It is this pressure that makes the compression packing an effective seal.

When using a compression packing it is important to restrain the forces that are transmitted by compression of the packing. These forces tend to expand the space in which the packing is housed. If the housing expands, compression relaxes and the seal can leak.

An object of this invention is to provide a rigid housing for a compression packing located for example at each end of a rotatable section of a circular conduit. Summary of the Invention

According to the present invention there is provided a conduit with a rotatable section between upstream and downstream fixed sections of the conduit, and comprising a sealing assembly for sealing gaps at the axial ends of the rotatable section, each gap being an axial gap between a cylindrical end portion of the rotatable section and an adjacent cylindrical end portion of one of the fixed sections of the conduit, the sealing assembly comprising :

- a stator flange fixed around the circumference of the end portion of each of the fixed sections of conduit, leaving a short length of the end portion protruding; - a rotor flange fixed around the circumference of the end portion at each end of the rotatable section, leaving a short length of the end portion protruding;

- two compression packings, each one being arranged between a stator flange and a rotor flange so as to cover the protruding short lengths of the opposed end portions and to cover the axial gap between the opposed end portions ;

- two compression bands, one arranged around each of the compression packings, and being adapted to compress the compression packing radially; and

- restraining means for resisting relative axial movement of the static sections of the conduit.

The restraining means may comprise one or more tie bars connected at their ends to the static sections of the conduit. Such a tie bar may extend within the

conduit, for example along the longitudinal axis of the conduit. Alternatively the tie bar or tie bars may be outside the conduit, connected at their ends to the static sections of the conduit for example by curved sections of the tie bar, or being connected to the stator flanges .

The compression packings support the weight of the rotatable section, unless the weight is taken by other means. With a small-scale rotatable section it may be satisfactory to rely only on the compression packings to support the weight, whereas with a larger-scale rotatable section there may be benefits in providing an additional means to support the weight. For example the rotatable section may be supported on rollers arranged below it.

As an option, the rotatable section may be pivotably connected to one or more link bars that are also

pivotally connected to a drive bar that is pivotably supported with its axis of rotation parallel to that of the rotatable section. Such a drive bar may be used to actuate rotation of the rotatable section, where the maximum angle of rotation is less than 180°. Where the drive bar is above the rotatable section the link bars and the drive bar may be arranged to support the weight of the rotatable section and its contents.

The present invention also provides means for controlling flow along a flow path by use of such a conduit as part of the flow path.

Brief Description of the Drawings

The invention will now be further and more

particularly described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of conduit of the invention, partly in pre-assembled form;

Figure 2 shows a perspective view of a modification of the conduit of Figure 1 ;

Figure 3 shows a perspective view of a modification of the conduit of figure 2 ;

Figure 4 shows a perspective view of the conduit of figure 3, after rotation of the rotatable section;

Figure 5 shows a perspective view of a modification of the conduit of figure 3; and

Figure 6 shows a cross-sectional view through the

modification to the conduit of figure 1.

Description of the Invention

Referring now to figure 1, this shows a perspective view of a conduit 10 which includes a rotatable section

11 between fixed sections 12. The rotatable section 11 and the fixed sections 12 are cylindrical tubes, with the same external diameters and the same internal diameters, and are arranged on a common axis such that there are narrow axial gaps 13 (only one is shown) at each end of the rotatable section 11, between the opposed ends of the rotatable section 11 and the fixed sections 12. The rotatable section 11 is supported on two pairs of rollers 72 (shown in figure 6) to ensure that as the rotatable section 11 is turned it remains coaxial with the

longitudinal axis of the conduit 10. The fixed sections

12 and the rollers 72 are connected together by a chassis (not shown) to ensure that the rollers 72 maintain true alignment with the axis of the conduit 10. As described in WO 2009/136200, the rotatable section 11 defines a discharge aperture 14. On either side of each gap 13 there are external flanges 15 and 16 welded to the rotatable section 11 and to the fixed sections 12 respectively, such that the centre of each gap 13 is located approximately mid-way between a pair of flanges 15 and 16. The gap between a pair of flanges 15 and 16 is substantially equal to the axial width of a packing ring 17, such that when packing rings 17 are inserted between the pair of flanges 15 and 16, they span the gap 13 between the rotatable section 11 and the adjacent fixed sections 12 of the conduit; and when pressed in a radially inward direction into the space between the flanges 15 and 16, the packing ring 17 comes in contact with the outer surfaces of the rotatable section 11 and the adjacent fixed section 12 of the conduit 10 adjacent to the gap 13. The radial compression of the packing ring 17 is achieved using an adjustable steel strap 18 provided with a screw adjuster 19.

In figure 1 the packing ring 17 and the steel strap 18 are shown in the assembled position at the left-hand end, and are shown in the pre-assembled state at the right-hand end. After insertion of the packing ring 17 between the flanges 15 and 16, the steel strap 18 is connected around the packing ring 17 and the screw adjuster 19 is adjusted to provide radial compression. (Although referred to as a ring, as is clear from the right-hand end of figure 1 the packing ring 17 consists of a length of packing material equal to the

circumference of the cylindrical tube 11 or 12.) The packing ring 17 seals onto the outer surfaces of the rotatable section 11 and of the adjacent fixed section 12, and also seals onto the opposed faces of the flanges 15 and 16. The flanges 15 and 16 are preferably sealed onto the rotatable section 11 and the fixed section 12 by welding, to further reduce the possibility of leakage. A wide range of materials are suitable for the packing ring 17. By way of example suitable packing rings might comprise: cross-plaited aramid yarns impregnated with PTFE; cross-plaited aramid and PTFE/graphite yarn, combined with a central core of temperature-resistant elastomer; or cross-plaited PTFE with a graphite

lubricant around a silicone rubber core. Radial compression of the packing ring 17 causes it to exert axial force on the flanges 15 and 16 and

consequently on the rotatable section 11 and on the adjacent fixed section 12. If the same degree of

compression is applied to both packing rings 17, the axial forces on the rotatable section 11 will balance and there will be no tendency for it to be displaced in an axial direction However, the axial forces acting on the fixed sections 12 will tend to force them apart, widening the gaps 13 and so reducing the compression of the packing rings 17 and reducing the sealing effect. To resist this, the fixed sections 12 are, in this embodiment, connected by a restraining strut or struts 20.

In principle the restraining strut may be either internal or external. A simple form of internal

restraining strut is a rod or tube that extends along the axis of the conduit 10 between one fixed section 12 and the other (e.g. strut 74 of figure 6) . At each end this would be attached to the inside wall of the fixed section 12 by one or more radial arms or a spider. This would have the benefit of allowing unimpeded 360° rotation of the rotatable section 11. However, the strut and the radial arms are located in the flow path where any debris carried by the flow may attach and accumulate.

In the embodiment as shown in figure 1 there are external struts 20. The external struts 20 extend between the fixed sections 12, and are shaped to pass over the flanges 15 and 16 and be attached directly to the

external surface of the fixed sections 12 for example by welding. To ensure all sections of the conduit 10 remains coaxial, the struts 20 are fixed at positions on

diametrically opposite sides of the axis. If a discharge chute (equivalent to the discharge chute 76 of figure 6) were attached to the discharge aperture 14, rotation of the rotatable section 11 would be impeded by these external struts 20, but in the application described in WO 2009/136200 such limited angular rotation is

sufficient .

The portions of the fixed sections 12 that project beyond the fixed flanges 16 act as spigots that can be flanged or flexibly connected to upstream and downstream sections of pipework.

In a modification the separation of the flanges 15 and 16 might correspond to the width of a plurality of packing rings 17. For example three packing rings 17 might fit between the flanges 15 and 16. The width of the adjustable steel strap 18 would be just less than the separation of the flanges 15 and 16, as in the embodiment of figure 1, so that in this case the steel strap 18 compresses all three packing rings 17 at once. Although the rotatable section 11 was described as being supported by rollers 72, in some cases the seals (that is to say the packing rings 17 and the steel straps 18) provide sufficient support for the rotatable section 11, so that rollers are not necessary and can be omitted.

Referring now to figure 2 there is shown a conduit 30 which is a modification of the conduit 10 of figure 1, the same components being referred to by the same

reference numerals. In the conduit 30 the rotatable section 11 with its flanges 15 locates between fixed sections 12, so there are narrow axial gaps 13 (only one is shown) . Large rectangular flanges 32 are welded to the fixed sections 12 (in place of the flanges 16), and the packing rings 17 (not shown) and the steel straps 18

(only one is shown) locate between the flanges 15 and the rectangular flanges 32. The left-hand end is shown before insertion of the packing ring 17, so that the gap 13 is visible . The fixed flanges 32 form side-panels of a chassis with tie-bars 33 joined directly to the flanges 32. As with the conduit 10 of figure 1, the portions of the fixed sections 12 that project beyond the fixed flanges 32 act as spigots that can be flanged or flexibly

connected to upstream and downstream sections of

pipework. The tie-bars 33 may provide mountings for rollers that ensure true alignment with the axis of the conduit 30 is maintained. The embodiments of figure 1 and figure 2 are shown in the context of a rotatable overflow valve as described in WO 2009/136200. It will be appreciated that the invention is applicable in other contexts. For example the downstream end of the conduit might be closed off, that is to say the downstream fixed section 12 might be sealed, so that all the liquid flowing into the upstream fixed section 12 must emerge through the discharge aperture 14. Turning the rotatable section 11 about a horizontal axis (as shown in the figures) enables the discharge aperture 14 to send the overflowing liquid either to the left or to the right, which may communicate with different outlets. In another application the discharge aperture 14 may be substantially circular, and communicate directly with an outlet pipe sealed to the rotatable section 11, so that the outlet pipe in

conjunction with the rotatable section 11 form a T or L junction. The longitudinal axis of the conduit 10 can, in this case, have any orientation. The rotatable seals constituted by the packing rings 17 and the steel straps 18 consequently enable the direction of the outlet pipe to be changed. In this application use of an internal restraining strut (e.g. strut 74) would be particularly appropriate, i.e. a strut that extends through the conduit 10 between the inlet fixed section 12 and the sealed fixed section 12 at the other end. At each end the strut would be attached to the respective fixed section 12. This would allow unimpeded 360° rotation of the rotatable section 11.

Referring now to figure 3 there is shown a conduit 40 which is a modification to the conduit 30 of figure 2, the same components being referred to by the same

reference numerals. In the conduit 40, the rotatable section 11 is supported by packing rings 17 (not shown) and steel straps 18 which fit between flanges 15 and rectangular flanges 41 that are linked by tie-bars 33, in the same manner as described above. The flanges 41 differ from the flanges 32 of figure 2 in extending a greater distance above the rotatable section 11. In the conduit 40 the rotatable section 11 is provided with two pairs of projecting lugs 42 (only one of which is visible in the figure), one at each end. The lugs 42 of each pair are fixed to the outside of the rotatable section 11, by welding, at diametrically opposite positions, a short distance in from the flange 15. Each lug 42 is pivotally connected by a link pin 43 to a pair of curved linking arms 44, and the upper ends of that pair of curved linking arms 44 are pivotally connected by a link pin 43 to one end of a cross beam 46. The opposite end of the cross beam 46 is similarly connected by curved linking arms 44 to the diametrically opposite lug 42, the straight-line distance between the link pins 43 at the opposite ends of the cross beam 46 being equal to the straight-line distance between the link pins 43 in the corresponding pair of lugs 42. The link pins 43 joining the curved linking arms 44 to a cross beam 46 and to a pair of lugs 42 are at the corners of a parallelogram.

Each cross beam 46 is fixed, by welding, to a drive shaft 48 which extends through bearings 50 mounted in the flanges 41 directly above the axis of rotation of the rotatable section 11. One end of the drive shaft 48 is provided with splines 52, so it can be driven by an external drive mechanism (not shown) . Hence the weight of the rotatable section 11 and its contents are supported by the bearings 50, the load being transmitted through the two cross beams 46 and the curved linking arms 44.

The rotatable section 11 can be turned by turning the drive shaft 48, so as to raise or lower the discharge aperture 14. As shown in figure 4, in one extreme of the rotation of the drive shaft 48 the discharge aperture 14 is near the upper side of the rotatable section 11 and the curved linking arms 44 on the left-hand side (as shown) come up against the outer surface of the rotatable section 11. Starting from the position shown in figure 4, by turning the drive shaft 48 clockwise the rotatable section 11 can be turned to the position shown in figure 3, and can be turned even further, eventually reaching another extreme in which the curved linking arms 44 on the right-hand side (as shown) would come up against the outer surface of the rotatable section 11. Hence the discharge aperture 14 can be raised and lowered, the rotatable section 11 being rotatable through an angle of about 45° in either direction from the position shown in figure 3. It will be appreciated that at every position of the drive shaft 48 the angle of the crossbar 46 from the horizontal is the same as the angle from the

horizontal of the diametral line between a pair of lugs 42. Thus the conduit 40 ensures the weight of the rotatable section 11 is carried by bearings 50 that are well clear of the water. Consequently the packing rings 17 do not have to carry that weight. However they do have to resist any sideways forces on the rotatable section 11, for example due to water flowing out through the discharge aperture 14.

Referring now to figure 5 there is shown a conduit 60 which is a modification to the conduit 40 of figures 3 and 4, the same components being referred to by the same reference numerals. In the conduit 60, the rotatable section 11 is supported between fixed rectangular flanges 61 that are linked by tie-bars 33, in the same manner as described above. The flanges 61 differ from the flanges 41 of figure 3 in extending a greater distance above the rotatable section 11.

The conduit 60 differs from the conduit 40 in that the lugs 42 are connected to the ends of the crossbars 46 by curved linking bars 64 each of which extends upwardly above the point at which it is connected to the crossbar 46, and at its upper end is pivotally connected by a pin 43 to a secondary crossbar 66 which is pivotally mounted at its midpoint by a stub shaft 68 fixed to the flange 61 directly above the drive shaft 48.

In most respects the conduit 60 operates in exactly the same way as the conduit 40. However in this case sideways forces on the rotatable section 11 are taken by the linking bars 64, the crossbar 46 and the secondary crossbar 66.

In a modification to the conduit 60, the positions of the drive shaft 48 and the stub shafts 68 may be interchanged, so the crossbars 46 are supported by stub shafts 68, and the secondary crossbar 66 is supported by the drive shaft 48. This operates in the same way.

Referring now to figure 6, this shows a conduit 70 which is a modification of the conduit 10 of figure 1, the same components being referred to by the same

reference numerals. In the conduit 70, the fixed sections 12 of tube are connected by an internal strut 74 with a spider 75 at each end, the spiders 75 being welded to the inside of the fixed sections 12 of tube. The rotatable section 11 is supported by rollers 72. The conduit 70 is also provided with an external discharge chute 76 welded to the outside of the rotatable section 11 to direct the liquid that flows out of the discharge aperture 14. This conduit 70 operates in the same manner as described above .

It will be appreciated that a conduit of the

invention may incorporate features shown in other

conduits. For example in each of the conduits 10, 30, 40 and 50 the rotary section 11 may incorporate a discharge chute 76 as shown in figure 6. As another example, a conduit may be supported by rollers 72 but be turned by a mechanism comprising a drive shaft 48, a pivoted crossbar 46 and a linking bar 44 connected to a projecting lug 42. As another example a conduit may be supported by a mechanism comprising a pivoted crossbar 46, a linking bar 44 or 64, and a projecting lug 42 (for example as shown in figures 3 and 4 or figure 5), but be turned by a different mechanism such as a linear actuator linked to another projecting lug.