WO2017093765A1

WO2017093765A1 - Improvements in fluid control devices

Info

Publication number: WO2017093765A1
Application number: PCT/GB2016/053825
Authority: WO
Inventors: Thomas HOULIHAN; Philip ELTON
Original assignee: Hydralectric Group Ltd
Current assignee: Hydralectric Group Ltd
Priority date: 2015-12-04
Filing date: 2016-12-05
Publication date: 2017-06-08
Anticipated expiration: 2018-06-04
Also published as: GB2547408A; GB201521455D0

Abstract

A hose assembly is provided with a cellular internal structure comprising an array of thin-walled partitions (12) within an outer tube (11). The partitions (12) divide up the interior volume of the tube (11) into a series of symmetrically arranged pockets (14) around a central passageway (13). The central passageway (13) is to convey an incompressible fluid, such as water. The pockets (14) contain a compressible fluid, such as air. The partitions (12) are of resiliently flexible material so as to permit the passageway (13) to expand if the pressure of the fluid contained therein increases. Expansion of the passageway (13) in this manner is balanced by an increase in the pressure of the fluid within the pockets (14). The tube (11) is surrounded by an outer reinforcing layer (17) to limit the extent of its possible expansion.

Description

Improvements in fluid control devices

This invention relates to fluid control devices, for example such as are to be found in domestic mains water supply systems.

The invention provides a hose assembly with a passageway therethrough for carrying a substantially incompressible fluid such as water under pressure, wherein the passageway is capable of expanding under increased pressure of the fluid contained therein, and wherein the assembly comprises means providing spring biassing force for opposing expansion of the passageway, and means for limiting the extent of its expandability.

By way of example, embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view through a form of conduit for a hose assembly according to the invention,

Figure 2 is a cross-sectional view of the conduit of Figure 1 incorporated in a hose assembly,

Figure 3 shows the conduit of Figure 1 at normal working pressure, and

Figure 4 shows the conduit of Figure 1 at maximum working pressure.

It is often necessary to make provision for pressure increases in supply systems for fluids such as water, due to their incompressible nature, For example, where a domestic mains water supply is to be boosted by a pump, pressure can build up in the supply line downstream of the non-return valve on the pump outlet due to repeated minor activations of the pump. The conventional way of alleviating potential problems from such pressure rises is to include an expansion chamber in the downstream line. The present invention recognises the possibility of a neater solution and proposes instead a hose assembly that is able to function as a normal supply line whilst allowing a limited degree of controlled expansion.

A preferred form of hose assembly comprises a conduit 10 having a cellular-like construction. The conduit 10 is elongate and has a constant cross-section, as seen in Figure 1. The conduit 10 comprises an outer cylindrical tube 11 with an array of thin-walled internal partitions 12 dividing up the interior volume into discrete sections. The conduit 10 is made of suitable elastomeric material so as to be resiliently flexible. In its preferred form, the conduit 10 is formed out of a single material in an extrusion process.

In this case, the conduit 10 has three partitions 12 arranged symmetrically around its longitudinal axis. The partitions 12 are shaped so that in their at-rest state (as seen in Figure 1), they combine together to define a generally circular central passageway 13 extending along the longitudinal axis of the conduit 10. This is the path along which the incompressible fluid, typically water, is intended to be conveyed. The three partitions 12 combine with the outer tube 11 to form three elongate pockets 14. These pockets 14 are to contain compressible fluid, preferably the same in each case and conveniently, air at normal atmospheric pressure. The incompressible fluid in the central passageway 13 is thus effectively surrounded by the three pockets 14 of compressible fluid.

The partitions 12 are shaped here with a fillet radius 18 at their junctions with the tube 11. The purpose of this configuration is to facilitate the mode of flexure of the partitions 12 and in particular, to enable them to "fold back" towards the innner wall of the tube 11 at extreme pressure (as seen in Figure 4). As seen in Figure 2, the conduit 10 is intended to be incorporated into a hose assembly of the kind that is conventionally used in fluid supply lines, eg for connections to pump outlets. The conduit 10 is seen here with a standard form of pipe connector fitting 15 swaged on to it at each end. It will be seen how the partitions 12 have been stretched over the spigot 16 of each pipe connector fitting 15 in order to provide fluid-tight communication with the bore 19 of each fitting for conveyance of (incompressible) fluid through the hose assembly via the central passageway 13 of the conduit 10.

It is important that the swaging process is effective in sealing the partitions 12 against the tube 11, in order to seal off the (compressible) fluid within each of the pockets 14. This is necessary to provide a body of compressible fluid capable of providing a counterbalancing pressure to the pressure of the fluid in the passageway 13. Also seen in Figure 2 is that the hose assembly comprises an outer reinforcing layer 17 extending around the outer circumference of the conduit 10. The reinforcing layer 17 is important, because it acts to constrain the conduit 10 in the sense of creating a limit to its expandability both axially and radially outwardly. For this purpose, the reinforcing layer 17 is in the known form of a sleeve of braided steel wire. In known manner, this form of reinforcing layer 17 does not hamper the resilient flexibility of the conduit 10. As noted above, Figure 1 shows the conduit 10 in its at-rest state. It will be in this state when there is no pressure in the passageway 13. In use in a hose assembly, there will normally be pressure in the passageway 13, from the (incompressible) fluid which it conveys. This fluid pressure will tend to flex the partitions 12 outwardly against the pressure of the (compressible) fluid contained within the pockets 14. Flexure of the partitions 12 will occur in this manner until an equilibrium position is reached in which the pressure in the passageway 13 is balanced by the pressure in the pockets 14. Figure 3 shows how the configuration of the partitions 12 has changed when the fluid in the passageway 13 has risen to normal working pressure. It will be noted that the volume of the passageway 13 has effectively increased, at the expense of the pockets 14, whose volume has decreased.

Flexing of the partitions 12 is able to continue in this manner and accommodate further rises in fluid pressure in the passageway 13, until the extreme condition of the conduit 10 shown in Figure 4 is reached. Here, the partitions 12 have flexed to practically their furthest extent, with the compression of the fluid in the pockets 14 providing a maximum amount of counterbalance to the pressure of the fluid in the passageway 13. The hose assembly described above can be used as a direct replacement for a standard hose. Although the passageway 13 in the conduit 10 described above is of a smaller bore (at normal working pressure) than a standard hose, it is nevertheless anticipated that this will be sufficient to be able to cope with fluid flow rates that are normally to be expected. It is thus anticipated that it will be possible to produce hose assemblies that have essentially the same overall external profile as a standard hose.

It will be understood that the hose assembly design described above could be adapted in many different ways. For example, the internal partitioning of the conduit could be varied in terms of its configuration and/or the number, disposition and extent of the pocket or pockets of compressible fluid. Also, the pockets could be filled with compressible fluid at pressures above normal atmospheric.

Claims

1. A hose assembly with a passageway therethrough for carrying a substantially incompressible fluid such as water under pressure, wherein the passageway is capable of expanding under increased pressure of the fluid contained therein, and wherein the assembly comprises means providing spring biassing force for opposing expansion of the passageway, and means for limiting the extent of its expandability.

2. A hose assembly as claimed in claim 1 wherein the conduit includes one or more pockets of compressible fluid such as air, with said one or more pockets providing or at least contributing to said spring biassing force.

3. A hose assembly as claimed in claim 2 wherein said one or more pockets extend the length of the conduit.

4. A hose assembly as claimed in claim 3 wherein said one or more pockets are arranged generally around the passageway.

5. A hose assembly as claimed in claim 4 wherein said one or more pockets are arranged symmetrically about the longitudinal axis of the conduit.

6. A hose assembly as claimed in claim 5 wherein there are three pockets.

7. A hose assembly as claimed in any one of claims 2 to 6 wherein the conduit is formed as an integral piece.

8. A hose assembly as claimed in claim 7 wherein the conduit is formed from elastomeric material.

9. A hose assembly as claimed in claim 8 wherein the conduit is formed in an extrusion process.

10. A hose assembly as claimed in any preceding claim wherein the expandability limiting means acts to limit expansion of the passageway transverse to its longitudinal axis.

11. A hose assembly as claimed in any preceding claim wherein the expandability limiting means acts to limit expansion of the passageway along its longitudinal axis.

12. A hose assembly as claimed in any preceding claim wherein said expandability limiting means comprises an external reinforcement layer.

13. A hose assembly as claimed in claim 12 wherein the external reinforcement layer is such as to allow the assembly to be resiliently flexible.