Field of the Invention

The present invention relates to the field of traps for rats and other rodents and in particular relates to traps for use in sewage systems.

Background of the Invention

A number of traps are known in the art. Types are known using poison for killing rodents and further a number of traps are known that are poison free. The poison free traps generally fall in two categories, these being mechanical traps and electrical traps.

Electrical traps are characterised by the killing mechanism being an electrical shock device almost instantly killing the rodent. Mechanical traps are

characterised by killing means that strikes the rodent and almost instantly kills the rodent. The killing means in mechanical traps are normally spring driven or gas pressure driven.

When operating a trap in a sewage system, the trap will normally be fixed in relation to a downstream sewage pipe or possibly to the sewage manhole wall. This means that a reduction of the flow area or an increase in flow resistance of the sewage pipe is introduced and a potential risk of clogging the pipe is hereby introduced.

Traditional traps have the disadvantage that they are difficult or impossible to install in older sewage systems, which is a paradox, as these sewage systems often are those in most need of rodent control. Sewage systems with a reduced flow capacity will also be difficult for the traditional traps to operate in as the increase in flow resistance will significantly reduce the sewage system basic function. Often there is a desire to frequently flush the sewage system and, in such circumstances, the traditional traps will have disadvantages. The flushing will in many instances remove the traps from their location, and risk blocking the outlet.

Additionally, the traditional methods are focused on killing rodents moving downstream to the manhole, thereby failing to kill the rodents that are living upstream to the manhole.

Object of the Invention

The objective of the present invention is to provide a rodent trap that will allow for a decreased obstruction of the sewage pipe and hence reduce the risk of clogging of the sewage system.

Description of the Invention

A first aspect of the present invention relates to a method for positioning a rodent trap in a sewage system, the method comprises the steps of:

- attaching one end of a support line to a rodent trap;

- lowering the rodent trap down a manhole in the sewage system by means of the support line, and keeping an end of the support line above the manhole;

- positioning the rodent trap in contact with the benching of the bottom part of the manhole; and

- tightening the support line, thereby providing a substantially vertical upwards force on the rodent trap and attaching the other end of the support line in the upper part of the manhole.

A second aspect of the invention relates to a method for positioning a rodent trap in a sewage system comprising the steps of:

- attaching one end of a support line to a rodent trap; - lowering the rodent trap down a manhole in the sewage system by means of the support line, and keeping an end of the support line above the manhole;

- positioning the rodent trap in contact with the benching of the bottom part of the manhole; and

- tightening the support line and attaching the other end of the support line in the upper part of the manhole, thereby providing a substantially vertical upwards force on the rodent trap; wherein the step of tightening the support line is performed such that only 5-90% of the weight of the rodent trap is carried by the support line.

By positioning the rodent trap in contact with the benching of the bottom part of the manhole, it is ensured that the sewage residue present in the water will not enter the killing device and the killing device will therefore be less prone to operational failure. The sewage pipes running through the manhole via an open channel will, as the free flow diameter is maintained to its full extent, be less prone to clogging and therefore a reduced amount of cleaning of the sewage system and the trap is required.

The supporting line has two purposes. It is used as means for lowering the rodent trap into contact with the benching of the bottom part of the manhole. Thereby, no personnel need to enter the manhole during the installation.

Furthermore, the supporting line is used to retain the rodent trap at a desired position. This is necessary, as a major part of the benching is sloped. The supporting line may e.g. be a rope or a wire.

In one or more embodiments, the method further comprises the step of mounting means adapted for preventing rats from entering the manhole through its outlet. Such means may e.g. be a device as disclosed in EP1828498, hereby incorporated by reference. The device comprises a jacket, a first gate plate, and a locking device. The jacket is adapted for mounting in a manhole pipe outlet, and the first gate plate is pivotally arranged inside the jacket. The locking device is arranged in connection to the first gate plate, where furthermore a second gate plate may be pivotally arranged at a distance from the first gate plate, inside the jacket and in communication with the first gate plate by means of a connection assembly. The jacket may have a shape substantially corresponding to the inner shape of the manhole pipe outlet and has an extent covering more than half of the circumference of said manhole pipe outlet. This method step secures that only the rats in a specific area, upstream to the manhole, has access to the manhole and rodent trap. In one or more embodiments, the method further comprises the step of mounting means adapted for preventing rats from entering the manhole through one or more of its inlets.

In one or more embodiments, the step of tightening the support line is performed such that a part of the weight of the rodent trap is carried by the support line. In one or more embodiments, the step of tightening the support line is performed such that only a part of the weight of the rodent trap is carried by the support line. If a manhole is flooded, air may be trapped within the rodent trap, thereby giving buoyancy to said trap. Hence, a certain weight is needed to keep the rodent trap in place under flooding of the manhole. In one or more embodiments, the rodent trap comprises a counterweight plate extending below its housing. It is then the counterweight plate that is positioned in contact with the benching of the bottom part of the manhole. The weight of the counterweight plate is preferably at least 3 kg, such as within the range of 3-15 kg, e.g. at least 4 kg, such as within the range of 4-14 kg, e.g. at least 5 kg, such as within the range of 5-13 kg, e.g. at least 6 kg, such as within the range of 6-12 kg, e.g. at least 7 kg, such as within the range of 7-1 1 kg, e.g. at least 8 kg, such as within the range of 8-10 kg, e.g. at least 9 kg. In one or more embodiments, the rodent trap, e.g. the housing, may comprise one or more counterweights to counteract the buoyancy of said rodent trap during flooding of the manhole. Such counterweights may have a weight of 1 -5 kg each. In one or more embodiments, the step of tightening the support line is performed such that 5-90% of the weight of the rodent trap is carried by the support line, such as 10-85%, e.g. 15-80%, such as 20-75%, e.g. 25-70%, such as 30-65%, e.g. 35-50%, such as 40-45%.

In one or more embodiments, the rodent trap comprises:

- a housing with a channel with a rodent entry opening, and a first opening in the upper wall leading to a chamber with defining walls and positioned above said channel; and

- a mechanical and/or electrical killing device positioned within the chamber; wherein the housing is mounted to a counterweight plate extending below said housing;

wherein the counterweight plate is positioned into contact with the benching of the bottom part of the manhole.

In one or more embodiments, the chamber is with air tight defining walls, and wherein the chamber is sized and configured to hold an air pocket of a size suitable to withstand water reaching the killing means of the mechanical and/or electrical killing device when the rodent trap is positioned at least 4 meters below the water level of a body of water, such as within the range of 4-6 meters, e.g. at least 5 meters below the water level of a body of water, such as within the range of 5-7 meters, e.g. at least 6 meters below the water level of a body of water, such as within the range of 6-8 meters, e.g. at least 7 meters below the water level of a body of water, such as within the range of 7-9 meters.

In one or more embodiments, the housing is mounted to the counterweight plate such that the channel will incline at an angle of within 5-40 degrees relative to the counterweight plate. This angle range is important, as a killed rodent, such as a rat, is thereby able to fall out of the channel, and will be washed away with the flowing sewage water. In one or more embodiments, the channel will incline at an angle of within 5-40 degrees relative to the counterweight plate, such as within 10-35 degrees, e.g. within 15-30 degrees, such as within 20-25 degrees. A third aspect relates to a rodent trap for being positioned in contact with the benching of the bottom part of a manhole in a sewage system, the rodent trap comprising:

- a housing with a channel with a rodent entry opening, and a first opening in the upper wall leading to a chamber with defining walls and positioned above said channel; and

- a mechanical and/or electrical killing device positioned within the chamber; wherein the housing is mounted to a counterweight plate extending below said housing.

Advantageously the killing device is a gas cartridge operated device. Such device has shown to be appropriate for such installation. Other types of killing devices may however also be used without limiting the scope of the invention. The gas cartridge operated device has the advantage of being usable in ATEX areas without the risk of igniting gas or flammable fluid.

Advantageously a signal indicating the activation of the killing device is

transmitted wirelessly to a receiving device located at top of the sewage manhole. Hereby electrical connections between the killing device and a communication device, placed at a distance from the killing device, may be avoided. The communication device eventually has a radio module enabling the device to send SMS messages to a computer.

In one or more embodiments, a window is positioned in a closed end of the channel, which makes the channel appear as an open-ended channel. This configuration allows the rat to see through the tunnel to the other side of the trap, whereby it will not hesitate to enter the trap.

In one or more embodiments, a pressure sensor is positioned within the chamber. A signal indicating the pressure within the chamber may, in one or more embodiments, be transmitted (by the pressure sensor or a separate signalling means) wirelessly to a receiving device located at top of the sewage system enabling SMS communication to a computer or other devices.

A fourth aspect relates to a method for catching rodents in a sewage system comprising the steps of:

- releasably attaching a rodent trap to an elongate positioning pole;

- attaching one end of a support line to said rodent trap;

- lowering the rodent trap down a manhole in the sewage system by means of the positioning pole, and keeping an end of the support line above the manhole;

- positioning the rodent trap on the benching of the bottom part of the manhole;

- attaching the other end of the support line in the upper part of the manhole; and

- releasing the positioning pole from the rodent trap, and withdrawing the positioning pole from the manhole.

A fifth aspect relates to a rodent trap for being positioned in contact with the benching of the bottom part of a manhole in a sewage system, the rodent trap comprising:

- a housing with a channel with a rodent entry opening, and a first opening in the upper wall leading to a chamber with defining walls and positioned above said channel;

- a mechanical and/or electrical killing device positioned within the chamber; and

- one or more counterweights to counteract the buoyancy of said rodent trap during flooding of the manhole.

As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

The invention is described in more detail in the following detailed description of a preferred embodiment, with reference to the figures.

Description of the Drawing

Figure 1 is a cross-sectional view of a manhole, wherein a rodent trap is mounted in accordance with various embodiments of the invention;

Figure 2 is a perspective view of a rodent trap in accordance with various embodiments of the invention;

Figure 3 is a cross-sectional view of a rodent trap in accordance with various embodiments of the invention;

Figure 4 is a perspective view of a housing of a rodent trap in accordance with various embodiments of the invention; and

Figure 5 is a perspective view of a counterweight plate of a rodent trap in accordance with various embodiments of the invention.

Detailed Description of the Invention

Figure 1 is a cross-sectional view of a manhole 200, wherein a rodent trap 100 has already been positioned into contact with the benching 210 of the bottom part of the manhole 200. The support line 300 is attached with one end to the rodent trap 100, e.g. via a coupling unit 500 as shown in Figure 4, and at the other end to a fixating tool 400 in the upper part of the manhole 200. The mounting and fixating tool may be provided with fastening means (not shown), e.g. in the shape of a clamp or cleat, to releasably fasten the support line 300 to the fixating tool 400. The coupling unit 500 may comprise a spring, such as a helical spring, such that by tightening the support line 300 and fastening it to the fixating tool 400, the spring in the coupling unit 500 will ensure that the rodent trap 100 is always subjected to a substantially vertical pull.

Figure 2 is a perspective view of a rodent trap 100, where the housing 1 10 is mounted to a counterweight plate 120 extending below said housing 1 10. Figure 3 is a cross-sectional view of the rodent trap shown in Figure 2. The housing 1 10 is mounted to the counterweight plate 120 such that the channel 11 1 will incline at an angle of about 30 degrees relative to the counterweight plate 120. The channel 1 1 1 has a rodent entry opening 1 12, and an opening in the upper wall leading to a chamber 114 with defining walls and positioned above said channel 1 1 1. A mechanical killing device 1 15 is positioned within the chamber 1 14. The killing device 1 15 is a gas driven device, where a killing piston is provided inside a housing. Upon triggering of a trigger mechanism within the channel 1 1 1 , the killing piston will propagate into the channel 11 1 with a significant force and hit the rodent that has activated the trigger mechanism. The rodent is attracted to the channel 11 1 by bait present behind the trigger mechanism. Other types of traps or killing devices may however also be used.

Figure 5 is a perspective view of an exemplary counterweight plate 120 of a rodent trap in accordance with various embodiments of the invention. The counterweight plate 120 is here shown with a vertically extending mounting plate 122 adapted for receiving the front of the housing. A cut-out or slot 124 is shown in the mounting plate 122 to provide access to the rodent entry opening 1 12 of the housing 110, when the housing 1 10 is mounted thereto.