WO2003069082A1

WO2003069082A1 - A barrier for preventing a rat from entering a sewage pipe

Info

Publication number: WO2003069082A1
Application number: PCT/DK2003/000092
Authority: WO
Inventors: Ernst Kragh; Torben Jensen
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-14
Filing date: 2003-02-13
Publication date: 2003-08-21
Anticipated expiration: 2004-08-14
Also published as: PL370769A1; DK174761B1; AU2003211856A1; EP1485541A1; DK200200226A

Abstract

A barrier serving for preventing a rat from entering a sewage pipe in the direction against the flow. The barrier comprises a first pivotal shutter (4) and a second pivotal shutter (5) located upstream of the first shutter (4). Both shutters (4,5) are forming an acute angle with the direction of flow when they are in a first angular position, in which at least the first shutter (4) is barring the aperture of the sewage pipe. From the first angular position, the first shutter (4) can be swung to a second angular position, in which it is clear of the aperture of the sewage pipe. The two shutters (4,5) are detachably locked to each other when they both are in their first angular position. The second shutter (5) is simultaneously detachably locked to a fixed stop (13) on the barrier. The rat can therefore not open the first shutter and thereby force the barrier. When the flow in the sewage pipe gets so strong that the rat cannot struggle its way upstream, the liquid pressure will force the second shutter (5) towards a second angular position in relation to the first shutter (4), whereby the locking engagement between the second shutter (5) and the stop (13) is released. Them, the liquid pressure is allowed to force the first shutter (4) to its second angular position, in which the liquid freely can flow through the sewage pipe but at such a force that the rat is not able to pass the barrier.

Description

A barrier for preventing a rat from entering a sewage pipe

The invention relates to a barrier for preventing vermin, such as a rat, from entering a sewage pipe in the direction against the flow and comprising a first shutter mounted on the barrier pivotally about a first axis and having a centre of gravity lying under the axis and pivotal between a first angular position in which the first shutter is forming an acute angle with the direction of flow and is at least substantially barring the aperture of the sewage pipe, and a second angular position in which the first shutter is at least substantially keeping the aperture clear.

Rats can cause great damage in a sewerage system by holing the sewage pipes or the joints between these pipes and hollowing the surrounding ground so that the pipes risk subsiding and becoming leaky. Via the sewerage system, the rats can furthermore travel great distances and spread over often large inhabited areas that then can become wasted to a considerable degree by the activities of the rats.

The migration of the rats in the sewerage system is therefore tried reduced by shutters placed in the sewage pipes with an inclination in the direction of the liquid flow in the pipes . The shutters serve for preventing the migration of the rats against the flow but not in the opposite direction.

However, it has turned out that these shutters constitute an effective means to control the rats. For the rats often move far away from their nest or habitat to look for food, or they are simply flushed through the pipes by strong liquid flows that periodically arise when it for example rains a lot.

The shutters prevent the rats from returning to their nests and regular habitats. Therefore, the population is scattered without possibility of normal contact between the individual individuals with the result that the opportunities of the population to breed are reduced to such an extent that the population eventually will die out.

Such a shutter is known from among others German patent publication DE 43 22 260 Al . However, this known shutter suffers the disadvantage that the rats are able to work the shutter open and then still travel against the flow.

In a first aspect of the invention, a barrier of the kind mentioned in the opening paragraph is provided that cannot be forced by e.g. a rat.

In a second aspect of the invention, a barrier of the kind mentioned in the opening paragraph is provided that cannot be opened by e.g. a rat .

In a third aspect of the invention, a barrier of the kind mentioned in the opening paragraph is provided that can be mounted over a passage of a sewage pipe in a well in a quick, easy and safe manner.

The novel and unique feature according to the invention, whereby this is achieved, is the fact that a second shutter is placed upstream of the first shutter, said second shutter being mounted on the barrier pivotally about a second axis and having a centre of gravity located under the axis, that at least one clasp is made on at least one of the two shutters, said clasp being arranged to cooperatively fasten the two shutters detachably together when the second shutter is in a first relative angular position in which it is forming a first angle with the first shutter, and to unfasten the two shutters from each other when the second shutter is swung towards a second relative angular position in which the second shutter is forming a second angle with the first shutter, which is smaller in relation to the first angle, that at least one first stop is made on the barrier, and that at least one second stop is made on the second shutter, which contact or is close to the at least one first stop when both shutters are in or near their first angular position and which is removed from the at least one first stop when the second shutter is swung towards its second angular position.

The first shutter bars the access to the second shutter in the direction against the flow when both shutters are in their first angular position. Therefore, a rat does not have a chance of manipulating the second shutter which is locked in the first position or near this position by one of the two opposite stop faces on the base and the second shutter respectively .

The first shutter is simultaneously locked to the thus locked second shutter by means of the clasp. The first shutter is therefore also locked in its first angular position or near this position. A rat is therefore not able to work or open the first shutter and thereby force the barrier.

In a preferred embodiment, the barrier furthermore comprises a base placed at an upper opening in the sewage pipe, that the first shutter is pivotally mounted on this base, that the second shutter is pivotally mounted on the first shutter, that the second axis is located at a distance under the first axis, and that the first stop is mounted on the base.

If a rat tries to swing the first shutter out of its first angular position to be able to force the barrier, the second shutter is lifted so that the first - and second stops hit each other and thereby lock the second shutter and thus the first shutter in their first angular positions or near these positions . According to the invention, the second shutter can be smaller than the first shutter, the second shutter not having to bar the aperture in itself but to function as lock to the first shutter in its first angular position. Thus, it is the first shutter that effectively bars the aperture of the sewage pipe in the first angular position of the shutters.

The mutual locking of the two shutters is released if the second shutter is swung from its first - to its second angular position by a sufficiently strong flow, whereby the first shutter now is allowed to swing from its first - to second angular position so that the aperture is cleared.

By a sufficiently strong flow is according to the invention meant a flow that is so strong that vermin are not able to struggle their way upstream. Even if both shutters are in their second position, vermin will therefore still not be able to pass the barrier.

When the above force of the flow in the sewage pipe has been reached, the shutters must however be able to easily swing out of their first angular position in direction towards their second angular position to thereby allow the liquid to flow unhindered through the sewage pipe .

According to the invention, the shutters can therefore be arranged with centres of gravity that are at such a distance from their respective swinging axes that the pressure of the liquid on the shutters exactly is able to easily lift their centres of gravity.

At smaller forces of flow in the sewage pipe the liquid must be able to pass the barrier while the shutters are in their first angular position in which they serve for preventing vermin forcing the barrier. Therefore, the shutters do not extend all the way down to the bottom of the sewage pipe in their first angular position but leave a suitable gap for passage of liquid at both shutters. However, the gaps must be so small that vermin cannot get through .

In order for the vermin not to be able to manage to manipulate the second shutter and thereby release the locking of the two shutters in their first angular position via the passage opening at the first shutter, this gap can advantageously be smaller than the one at the second shutter.

According to the invention, the base can be U-shaped with a body and two downwardly facing tabs and be provided with stops for the first shutter in the first - and second angular positions respectively of this shutter. On the base, a barrier plate can furthermore be mounted extending mainly from the body of the base to a point so close to the first shutter that the vermin cannot crawl over the shutter.

It is important that the barrier is positioned correctly in relation to the sewage pipe, that is so that the shutters are extending transversely in the pipe at the correct inclination in the direction of flow. For this purpose, the barrier according to the invention can be provided with guides adapted to corresponding guides in or at the mouth of the sewage pipe.

It is also important that the barrier is securely fixed in relation to the sewage pipe so that the vermin cannot move or lift the barrier and thereby be able to crawl under it.

Normally, the barrier is mounted in a well with a passage for the liquid in the sewage pipe. The barrier can then be provided with an eccentric for fixing the barrier against the interior wall of the well. The invention will be explained in greater details below, describing only exemplary embodiments with reference to the drawing, in which

Fig. 1 is a perspective end view of a barrier according to the invention,

Fig. 2 is a perspective view of the barrier in fig. 1 mounted in a fractionally shown well with a passage for a sewage pipe,

Fig. 3 is a top view of the barrier in fig. 2,

Fig. 4 is a longitudinal section of the barrier in fig. 2 in a first barring position,

Fig. 5 is a longitudinal section of the barrier in fig. 2 in a second barring position,

Fig. 6 is a longitudinal section of the barrier in fig. 2 in a position in which the barrier is released, and

Fig. 7 is a longitudinal section of the barrier in fig. 2 in a position in which the barrier is clear of the passage.

In the following it is assumed that the barrier according to the invention is mounted in a well over a passage for a sewage pipe in a sewerage system and that the vermin is a rat.

As seen in fig. 1, the barrier mainly is composed of a U- shaped base 1 having a horizontal body 2 with two downwardly facing tabs 3, and of a first shutter 4 and a second shutter 5 which, in the figure, is located behind the first shutter and therefore illustrated in dotted line.

The first shutter 4 has a flap 6 with two tabs 7 and is pivotally mounted on the base by means of a first swing shaft 8 journaled in the tabs 3 of the base and the tab 7 of the first shutter respectively.

The second shutter 5 has a flap 9 with two tabs 10 extending through slots 11 in the flap 6 of the first shutter and pivotally mounted on the first shutter 4 by means of a second swing shaft 12 journaled in the tabs 7 and 10 respectively of the first and second shutters.

On the body 2 of the base, a fixed first stop 13 is furthermore made whereas a second stop 14 is made on one of the flaps 10 of the second shutter. On same flap 10 is also made a hook 15 extending downwards from the slot 11 on the downstream face of the flap 6 of the first shutter. A fixed pin 16 serves for restricting the pivoting of the first shutter 4 towards the base 1.

Fig. 2 shows the barrier mounted in a well 17 with a passage 18 for a sewage pipe (not shown) connected to two sleeves 19 flushing with the passage.

On the body 2 of the base, a hook 20 is mounted for lowering or lifting the barrier when it is to be mounted in or removed from respectively the well 17. An eccentric 21 serves for fixing the barrier against the wall 22 of the well so that it cannot be moved or lifted by neither the liquid flow or the rat, whereby the rat, if occasion should arise, could get a chance to crawl under the barrier.

Fig. 3 is a top view of the well 17 in fig. 2 with the barrier mounted according to the invention. For supporting the base of the barrier, first and second seats 23 and 24 respectively are made in the well. The first seat 23 has a quadrangular contour and the second seat 24 an almost arrow-shaped contour. The body of the base has a first guide 25 fitting the first seat

23 and a second guide 26 fitting the second seat 24. Both guides are made as extensions of the body 2 of the base on both sides of the tabs 3.

When the barrier is to be mounted in the well, it is lowered by means of the hook 20 in such a way that the first guide 25 is embedded in the first seat 23 and the second guide 26 in the second seat 24, whereas the tabs 3 is extending a little along the sides of the passage. Thereby, the barrier is guided so that it will always be orientated quite correctly in relation to the passage and the direction of flow in this passage.

It is to be noted that the above-mentioned guidance on mounting of the barrier in the well only is to be taken as an example as many other ways of guiding the barrier correctly in place in the well are possible within the scope of the invention. The guidance can possibly be spared completely, it then being the installer who ensures that the barrier is mounted in correct position in the well.

In this case, four air holes 27 are furthermore made in the body 2 of the base, through which holes the passage 18 can communicate with open air via the well 17.

Figs. 4 - 7 show the different stages of the functioning of the barrier.

As shown, the swing shaft 8 of the first shutter 4 is located a distance above the passage 18 of the well 17. The first shutter 4 can therefore swing from the first angular position in fig. 4 to the second angular position in fig. 7, in which the shutter is swung completely free of the passage which thereby will allow fully passage of the liquid, for example contaminated water running in the sewer. The second angular position of the first shutter 4 is defined by the fixed pin 16 functioning as stop to the shutter, whereas its first angular position in this case is defined by the body 2 of the base and the upper end of the flap 6 of the first shutter, which will hit the body 2 when the shutter is in its first angular position.

A counterbalance 28 is fitted at the top of the first shutter.

The resultant centre of gravity of the weight of the first shutter and the counterbalance on the shutter is located under the swing shaft 8. The shutter will therefore always seek towards its first angular position when it is not loaded.

However, the centre of gravity is located so suitably far under the swing shaft 8 that the shutter only can swing out of its first angular position when it is loaded by exactly so strong a liquid pressure that a rat cannot struggle its way upstream.

As mentioned above, the second shutter 5 is pivotally mounted on the second swing shaft 12 journaled in the tabs 7 of the first shutter 4 at a distance below the first swing shaft 8. A second counterbalance 29 is fitted at the bottom of the shutter. The resultant centre of gravity of the weight of the second shutter and the counterbalance on the shutter will be under the swing shaft 12 of the shutter. The second shutter will therefore always seek towards the first angular position in fig. 4 when it is unloaded.

However, the centre of gravity is located at such a distance below the swing shaft 12 that the shutter will swing from its first angular position in direction towards the second angular position in fig. 6 when the liquid in the passage has reached the above-mentioned flow force at which the first shutter will tend to swing away from its first position. In their first angular positions, both shutters 4 and 5 are forming an acute angle with the direction of flow indicated by the arrow. The first shutter is for example forming an angle of between 30° and 60° with the direction of flow, whereas the second shutter for example is forming a somewhat larger angle of between 70° and 90° with the direction of flow.

The first angular position of the second shutter 5 is defined by its hook 15 which is extending via the slot 11 in the flap 6 of the first shutter to and contacting the downstream face of this flap, whereby the two shutters are locked in the mutual first angular position in figs. 4 and 5 against being able to swing to a greater angle in relation to each other, whereas the hook on the other side is made with a clearance to allow the second shutter to swing towards or to the smaller angle in figs. 6 and 7 in relation to the first shutter.

The first - and second stops 13 and 14 on the body 2 of the base and the tab 10 of the second shutter respectively are located at a short distance from each other in the case shown. If a rat tries to work the first shutter up from its first angular position to thereby be able to force the barrier, it will only be able to swing the shutter a small angle as the second shutter then is lifted so that its stop 14 will hit the stop 13 of the base, as shown in fig. 5.

The first shutter 4 is thus locked by the hook 15 to the second shutter 5 which in its turn is locked to the base when the stop 14 of the shutter hits the stop 13 of the base.

When liquid is running in the sewage pipe at the above force at which the rat is not able to struggle its way upstream, the second shutter 5 is swung from the angular position in figs. 4 and 5 to the second angular position in fig. 6 in relation to the first shutter 4. Thereby, the second stop 14 is swung free of the first stop 13, after which the flow now is allowed to swing the first shutter up to the angular position in fig. 7, in which the shutter is clear of the aperture of the passage which thus freely can be flown through by the liquid which however now is flowing at such a force that the rat cannot struggle its way upstream but normally is carried along by this flow.

A barrier plate 30 is extending from the body 2 of the base to close down to the flap 6 of the first shutter 4 near the swing shaft 8 of the shutter. The barrier plate prevents the rat from being able to force the barrier by crawling over the first shutter 4.

The first shutter 4 constitutes the primary protection against the rat being able to force the barrier. Therefore, it is extending over most of the cross section of the passage leaving a gap between the bottom edge of the shutter and the bottom of the passage. This gap allows the liquid to pass the passage freely at smaller forces of flow but it can however not be so large that the rat can squeeze through the gap.

A suitable size of the gap would be 8 - 10 mm in the first angular position in fig. 4 and a maximum of 15 mm in the slightly lifted angular position in fig. 5, in which the first shutter is detachably locked against further pivoting.

As appears from the above description, the second shutter almost functions as a lock keeping the first shutter detachably locked, in the first angular position in figs. 4 and 5 in relation to the said first shutter, against being swung to the second angular position in fig. 7, in which the passage is completely open.

The second shutter is therefore smaller than the first shutter, and the second gap 32 between the bottom edge of the second shutter and the bottom of the passage is also so much larger, for example 10 mm, than the first gap 31 between the bottom edge of the first shutter and the bottom of the passage that the rat will not be able to manipulate the second shutter via the first gap 31 to swing from the first to the second angular position so that the first shutter can be opened.

Claims

Patent claims

1. A barrier for preventing vermin, such as a rat, from entering a sewage pipe in the direction against the flow and comprising a first shutter (4) mounted on the barrier pivotally about a first axis and having a centre of gravity lying under the axis and pivotal between a first angular position in which the first shutter (4) is forming an acute angle with the direction of flow and is at least substantially barring the aperture of the sewage pipe, and a second angular position in which the first shutter (4) is at least substantially keeping the aperture clear characterized in that the barrier furthermore comprises a second shutter (5) placed upstream of the first shutter (4) and mounted on the barrier pivotally about a second axis and having a centre of gravity located under the axis, - at least one clasp (15) made on at least one of the two shutters and arranged to cooperatively fasten the two shutters (4; 5) detachably together when the second shutter (5) is in a first relative angular position in which it is forming a first angle with the first shutter (4), and to unfasten the two shutters (4;5) from each other when the second shutter (5) is swung towards or to a second relative angular position in which the second shutter is forming a second angle with the first shutter (4) , said second angle being smaller in relation to the first angle, at least one first stop (13) made on the barrier, and at least one second stop (14) made on the second shutter (5) , which contact or is close to the at least one first stop (13) when both shutters (4; 5) are in or near their first angular position and which is moved away from the at least one first stop (13) when the second shutter (5) is swung towards its second angular position.

2. A barrier according to claim 1, characterized in - that the barrier comprises a base (1) mounted at an upper opening in the sewage pipe, that the first shutter (4) is pivotally mounted on this base (1) , that the second shutter (5) is pivotally mounted on the first shutter (4) , that the second axis is located a distance below the first axis, and that the at least one first stop (13) is mounted on the base (1) .

3. A barrier according to claim 1 or 2 , characterized in that the second shutter (5) is smaller than the first shutter (4) .

4. A barrier according to claim 1, 2 or 3, characterized in that the centres of gravity of both shutters (4; 5) have such a distance from their respective axes that the flow in the sewage pipe is able to swing the shutters (4; 5) from their first angular position in direction towards their second angular position when the flow is sufficiently strong to prevent vermin from struggling their way up against the flow.

5. A barrier according to any of the claims 1 - 4, characterized in that the first shutter (4) is forming an angle of between 30° and 60° with the direction of flow, whereas the second shutter (5) is forming an angle of between 70° and 90° with the direction of flow when both shutters (4; 5) are in their first angular position.

6. A barrier according to any of the claims 1 - 5, characterized in that the bottom edge of the first shutter (4) has a smaller distance from the bottom of the sewage pipe than the bottom edge of the second shutter (5) when both shutters (4; 5) are in their first angular position.

7. A barrier to any of the claims 1 - 6, characterized in that the bottom edge of the first shutter (4) has a distance of maximum 15 mm from the bottom of the sewage pipe when the shutter (4) is in the first angular position or near this position.

8. A barrier to any of the claims 1 - 7, characterized in - that the base (1) has a U-shaped cross section and an elongated body (2) extending mainly horizontally and having two downwardly facing tabs (3), that the first shutter (4) is pivotally journaled in the two tabs (3), and - that the base (1) has a first stop (2,6) for the first shutter (4) in its first angular position and a second stop (16) for the first shutter in its second angular position.

9. A barrier to any of the claims 1 - 8, characterized in that the first shutter is made with a U-shaped cross section with a flap (6) and two tabs (7), and that the second shutter (5) is pivotally journaled in the two tabs (7) of the first shutter (4) .

10. A barrier to any of the claims 1 - 9, characterized in that the at least one clasp is a clasp (15) made on the second shutter (5) and extending behind this, shutter via a slot (11) in the first shutter (4) .

11. A barrier to any of the claims 1 - 10, characterized in that a barring plate (30) is made on the base (1) that is extending mainly from the body (2) of the base (1) to so close to the flap (6) of the first shutter (4) that the vermin are not allowed to pass .

12. A barrier to any of the claims 1 - 11, characterized in that the base (1) is made with guides (25,26) fitting corresponding guides (23,24) in or at the sewage pipe and cooperatively arranged to ensure that the barrier is mounted in a desired way at the upper opening of the sewage pipe.

13. A barrier to any of the claims 1 - 12, wherein the barrier is placed in a well (17) having a passage (18) for liquid in the sewage pipe, characterized in that the barrier is provided with a pivotal eccentric (21) for fixing the barrier against the wall (22) of the well (17) .