BACKGROUND OF THE INVENTION When connecting smaller branch lines to sewer or stormwater mains it is known to use rubber sealing rings. These may be fitted for example between the outside of the incoming pipe and the inside of a receiving aperture in the wall of a manhole. In order to form a fluid tight seal against the inside of the aperture and the pipe various types of internal expansion hoops and clamps are used. Generally however the devices currently employed do not provide sufficient sealing force against the irregular and rough concrete surface of the aperture. Existing clamps also tend to be time consuming and difficult to install.

SUMMARY OF THE INVENTION It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly a sealing ring is disclosed for connecting a stormwater or sewer pipe into an aperture, said ring having inner and outer facing surfaces which in an undeformed configuration of the ring are adapted to fit respectively over the outer circumference of said pipe and into said aperture and said ring further including means for axially deforming an internal circumferential portion of the ring located between the inner and outer surfaces whereby said inner and outer surfaces are displaced to seal against said pipe and aperture.

Preferably said means for deforming comprise a plurality of compression members arranged around the circumference of the ring.

Preferably said means for deforming further comprise axially spaced annular plates or chain links with threaded rods or bolts extending therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS Currently preferred examples of the invention will now be described with reference to the attached drawings in which:- figures 1 and 2 are schematic perspective end views of a sealing ring according to this concept, figure 3 is a cross-sectional view along the lines A-A of figure 1, figure 4 shows a connection between a branch sewer pipe and a manhole housing using the sealing ring of figure 1, figure 5 is a cross-sectional view along the lines B-B of figure 4, figure 6 is an end view of a sealing ring according to a second embodiment of the invention, figure 7 is a detailed perspective view of part of the ring outer edge shown in figure 6, figure 8 is a detailed edge view of part of the ring of figure 6, and figure 9 is a perspective view of a modified form of chain link for use with the sealing ring of figure 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to figures 1 to 3 the ring indicated generally as 1 is preferably made from any suitable form of chemically inert and elastically deformable material such as natural rubber. The inside surface 2 with this embodiment may be rounded in the axial direction and in the undeformed configuration shown is dimensioned to slide over the outside of a sewer pipe or the like. The outer surface 3A of the ring is dimensioned for a sliding fit into a pipe receiving aperture of a manhole housing. One outer edge of the ring is formed into a bead 3B of larger diameter which in a position of use as described later bears up against the outside of the manhole housing around the aperture. An annular steel plate 4 is also fitted radially just inside the bead 3B and on installation forms an outer exposed face of the ring. Threaded rods 5 extend through the plate 4 with nuts 6 fitted thereon.

In the cross-section of figure 3 the ring is seen to have a second internal annular steel plate 7 spaced from plate 4.

These plates 4 and 7 are thus positioned one on each side of ring material 8 which forms the inner and outer sealing surfaces 2 and 3A referred to earlier. The threaded rods 5 are anchored to the internal plate 7 and extend out through apertures in the external plate 4. By turning down the nuts 6 on the rods 5 it will thus be seen that the material 8 between the plates is compressed in the axial direction as shown by arrows C. This results in the surfaces 2 and 3A being deformed inwardly and outwardly as indicated by the broken lines.

In use the ring in its undeformed configuration is push fitted between the inside of an aperture 9 in a manhole housing 10 and the outside of a sewer pipe 11 as shown in figures 4 and 5. As mentioned earlier the ring is located in the aperture 9 so that the bead 3B rests up against the outside of the manhole housing and the nuts 6 are exposed.

Once the ring is in place the nuts are tightened as required to progressively deform the surfaces 2 and 3A to tightly grip and seal against the inside of the aperture 9 and the pipe 11.

The second embodiment of the invention shown in figures 6 to 8 works in a similar manner to the ring of figures 1 to 5 except for the omission of the bead 3B. The main components here that correspond in function to those of figures 1 to 5 are indicated by the same numbers which however are primed (') to distinguish them.

To enable a large range of pipe sizes to be economically catered for this ring 1'is formed from a commercially available length of square section rubber moulding (say for example 40 mm x 40 mm) in which the ends thereof have been vulcanised or otherwise secured together. By varying the length and cross-section of the rubber moulding used a wide range of different sized rings can be economically formed.

This avoids the requirement with the first embodimnent of having to mould a separate ring for each size of pipe. With this second embodiment the inside and outside surfaces 2' and 3A'of the ring are preferably straight in the axial direction. The clamping mechanism in this case comprises a circumferential series of chain links 12, 13 on opposite sides of the ring. The links are stepped at each end to interfit and are joined by stainless steel bolts 14 with nuts 6'threaded thereon. Preferably the links are formed from a glass filled nylon such as that sold under the trade name"Duramid N61520BK-104"by Edplas Pty. Ltd. of Sydney NSW. The size and shape of the links for each side are preferably standardised for economy of manufacture with the number being fitted varying according to ring diameter.

Preferably the links 12 on the inner concealed bolt head side of an installation are formed with parallel ribs 15 which abut the sides of the bolt head to prevent rotation.

The links 13 on the opposite exposed side are flat around the nuts 6'to enable the application of a wrench.

Tightening the nuts 6'causes the material 8'between the links 12,13 to compress in the axial direction whereby the surfaces 2'and 3A'deform inwardly and outwardly to seal in a similar manner to the first embodiment.

A variation of the aformentioned chain links is shown in figure 9. In this case the central portion 16 is thickened to a centre ridge 17. This additional thickness of material serves to increase the rigidity of the link and its resistance to gradual outward deformation over time when the ring is compressed.

It will thus be appreciated that this invention at least in the form of the embodiments described provides a novel and improved sealing ring for sewer and stormwater drainage systems. Clearly however the examples disclosed are only the currently preferred forms of the invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the shape and configuration of the sealing surfaces, the design of the compression mechanism and the material used for constructing the ring may be changed according to application.