This invention relates to a protection unit against ratbite on sewage pipes. CN 201 943 180 discloses a protection unit, to preventing rats from leaving a sewage system through openings in the end of the pipes being part of the sewage system.

The protection unit constitutes of a cylinder being opened upwards for being connected to a sewage pipe. Downwards and along the surface, a net structure is provided.

This protection unit is intended to prevent the possibility for rats to leave the end pipe in a sewage system.

Now it is a purpose with the invention to realise a protection unit, in particular to prevent rats or other pets, to leave a sewage system, especially by biting those edges existing in the sewage system.

The purpose is realised through a protection system defines in the preamble of claim 1, that is characterized in, that the protection unit is mounted on an edge of an end termination of a sewage pipe or on an edge forming a transition between two sewage pipes, where said sewage pipes having different diameters, said protection unit consists of a strengthening part covering the edge. In those cases where sewerage pipe that are connected to each other and having different diameters, thereby creating an edge, it is advantageous if, as stated in claim 2, that protection unit consist of a disk, said disk is formed as a ring with a hole, said ring having the same dimensions as the edge. In order to secure the free ends of a pipe in a sewage system it is expedient as stated in claim 3, that the disk has at least one downward pointing flange, that abuts against that part of the drainage surface, that contiguous the edge or, as stated in claim 4, that the disk is formed as a ring having two elastic flanges for providing a pressure against the drainage pipe or, as stated in claim 5, that the disk is formed as a ring having two flanges, each flange is provided with an inner self-cutting thread.

Expedient, as stated in claim 6, is the protection unit made in a metal or a metallic alloy.

The invention will now more fully be explained in connection with the drawing on which

Fig. 1 illustrates part of a pipe system in a sewage system, whereas Fig. 2 the pipe system on fig. 1 in cross section.

On the figures 1 denotes a funnel shaped pipe, being connected to a sewage pipe 2 that via an edge 8, is connected to a sewage pipe part 2a, having a bigger diameter than the sewage pipe 2.

The sewage pipe part 2a is connected to a sewage pipe 3. These sewage pipes can be manufactured in a plastic material, such as PVC or the like. To the end of funnel shaped pipe 1, a not shown sewage pipe can be connected, being formed of cement, clay or the like hard material. The non-shown sewage pipe can be fixes by use of a strap 9.

As it can be seen from fig. 2, the funnel shaped pipe 1 is connected to the sewage pipe by use of an annular seal (O-ring) and a strap 9a.

The sewage pipe 3 is connected to the sewage pipe part 2a by an annular seal 7. As it further can be seen, protrudes the free end of the sewage pipe 2 into the funnel shaped pipe 1.

This free end is terminated by an edge, that for inst. a pet such as a rat can bite in, and thereby bite hole in the sewage pipe, and on this way escape out of the sewage system.

To preventing this, is according to the invention, a metal ring 4 is fastened around the sewage pipes free end, that covers the edge of the sewage pipe, said metal ring being formed with downward going flanges. The metal ring is placed on the sewage pipes fee end by use of a press force or an inner self-cutting thread.

In the same way, the free end of the sewage pipe 3 can be provided by a metal ring 5.

The above mentioned edge 8 can also be protected against bite, simply to place a metal disk on the edge which could be done by use of an adhesive.

By the invention, an effective measure is provided in securing that rats cannot bite in pipes of a sewage system end thereby escaping from the sewage system.