WO2007068971A1

WO2007068971A1 - Rodent trap

Info

Publication number: WO2007068971A1
Application number: PCT/GB2006/050424
Authority: WO
Inventors: Andrew J. Brigham
Original assignee: Rentokil Initial Plc
Priority date: 2005-12-12
Filing date: 2006-12-01
Publication date: 2007-06-21
Also published as: GB0525268D0

Abstract

The present invention provides? for a rodent trap (10) , comprising a housing (12) having first and second openings (18a, 18b) providing access to a chamber (20) located within said housing. First and second detection means (32a, 32b) are provided adjacent said openings respectively, and arranged to detect the presence of a rodent. A timing means is provided which is arranged to be initiated when one of said detection means detects the presence of a rodent. Further, there are provided first and second closure means (22a, 22b) associated with said first and second openings respectively and arranged to be triggered by way of the detection means to prevent escape from said chamber, said closure means being arranged to be triggered when both said first and second detection means detect the presence of a rodent, within a period as determined by said timing means. The trap is arranged to receive extermination means operable to exterminate said rodent subsequent to activation of said closure means.

Description

RODENT TRAP

The present invention relates to a rodent trap and particularly, but not exclusively, to a rodent trap for the humane trapping and/or extermination of a rodent.

The many known methods of rodent control include the use of poisons resulting in the extermination of the rodent, the use of a trap to trap the rodent for the purpose of release in an area remote from the location of capture, or the simultaneous trapping and extermination of the rodent.

These methods however exhibit disadvantages. In particular, the use of poisonous substances has the drawback that animals (such as domestic pets or livestock), or indeed humans, may unintentionally ingest the poisonous substance. Also, there will typically be poisonous residues left by rodents exterminated using poison, and these poisonous residues are likely to be detrimental to the environment. Further, there are certain environments where the use of poison is impractical, or even forbidden (e.g. in food-preparation environments).

Of the other type of rodent control (i.e. traps), probably the most popular method is the use of a spring-loaded trap in combination with bait. When a rodent attempts to obtain the bait a spring-loaded arm/lever is triggered to trap and (usually) exterminate the rodent simultaneously. However, such traps may inadvertently be triggered by humans or domestic animals causing failure of their intended purpose and possible injury to, for example, the domestic pet concerned. Also, such traps can be unsanitary because blood (and possibly other bodily fluids) and/ or bacteria may be released into the environment and may be passed from the trapped rodent to the trap, and from there may be passed onto to a user setting the trap.

Further, such traps are considered to be inhumane as they often only injure the rodent, or trap the rodent by a limb, and thus cause the rodent pain and a possibly drawn-out death. There are also known rodent control devices which operate using a combination of the above methods of poisoning and trapping. These types of devices comprise a housing in which is located bait which has been poisoned and which acts to lure the rodent into the housing. The housing is configured so as to prevent the rodent escaping and so once the rodent has consumed the poisonous bait and been exterminated, its body is retained within the housing. Such devices are suitable for use in commercial environments having large areas where operator visits to each trap (to empty the trap) are infrequent and where it is necessary to conceal the body of the rodent from the surrounding environment.

However, these methods also suffer some of the same drawbacks as the other rodent control method implementing poison as mentioned above (i.e. the use of poison in an environment where food is prepared creates a risk that food will become contaminated).

The use of poisons in rodent control methods also suffers the drawback that many types of rodent have developed resistance to the poisons used against them.

The present invention seeks to provide for a rodent trap having advantages over known such rodent traps/rodent control methods.

According to an aspect of the present invention, there is provided a rodent trap, comprising: a housing having first and second openings providing access to a chamber located within said housing; first and second detection means adjacent said openings respectively, and arranged to detect the presence of a rodent; timing means arranged to be initiated when one of said detection means detects the presence of a rodent; first and second closure means associated with said first and second openings respectively and arranged to be triggered by way of the detection means to prevent escape from said chamber, said closure means being arranged to be triggered when both said first and second detection means detect the presence of a rodent, within a period as determined by said timing means; the trap being arranged to receive extermination means operable to exterminate said rodent subsequent to activation of said closure means.

An advantage of such a rodent trap is that a rodent exterminated therein eliminates the requirement for poison and so avoids the associated drawbacks. Further, such a rodent trap retains the body of an exterminated rodent therein for disposal at a later time by an operator.

Preferably, said housing is configured to allow opening thereof.

Further said housing comprises a base portion and a lid portion, said lid portion and base portion arranged to cooperate to enclose a volume which forms said chamber.

In particular said lid portion and base portion are hingedly attached to each other.

Advantageously edges of contact between said base portion and lid portion are provided with a sealing member to form a seal between the base portion and lid portion of said housing when the housing is in a closed state.

If required said first and second detection means comprise electro-optic detection means.

Also said electro-optic detection means comprises an infrared detection means.

Alternatively first and second detection means comprise a pressure sensor arranged to output a detection signal when a rodent exerts pressure thereon. Conveniently said pressure sensor is arranged to output said detection signal only when a pressure equivalent to a rodent weight of >70 grams is exerted on said pressure sensor.

Preferably said first and second closure means comprise a door mechanism comprising first and second doors moveable between an open position thereby allowing a rodent access to said chamber by means of said openings, and a closed position where said openings are blocked and escape from said chamber is prevented.

Further said doors are pivotable between said open and closed positions about an axis perpendicular to the plane of said doors.

In particular said rodent trap further comprises a catch means arranged to act upon said door mechanism to retain said doors in said open position when said rodent trap is in an untriggered state,

Advantageously said catch means is arranged to disengage from said door mechanism to release said doors, thereby allowing them to move to said closed position, when said detection means detects the presence of a rodent in said trap.

If required said door mechanism further comprises a rod connected to said doors and extending therebetween along the length of said housing, said rod defining an axis about which the doors are arranged to pivot.

Also said catch means is arranged to engage with said rod to retain said doors in an open position in said untriggered state of said trap, and to disengage said rod to allow said doors to move to said closed position when said detection means detects the presence of a rodent in said trap.

Conveniently said rodent trap further comprises biasing means arranged to urge said doors to said closed position. Preferably said biasing means comprises a beam torsion spring.

Alternatively said biasing means comprises a spiral spring.

Alternatively said biasing means comprises a compression spring.

Alternatively said biasing means comprises a tension spring.

Further peripheral edges of said doors are configured to form a seal between the peripheral edges thereof and the periphery of said openings when said doors are in said closed position.

In particular said extermination means comprises electrical means operable to electrocute a rodent trapped in said trap.

Advantageously said extermination means comprises a source of poisonous gas.

If required said extermination means further comprises a means arranged to introduce said poisonous gas into said chamber.

Also, the rodent trap is arranged to receive a gas canister for the storage of said poisonous gas.

Conveniently said means arranged to introduce poisonous gas into said chamber comprises: a gas release valve having an inlet means arranged to engage with an outlet means of said gas canister, said gas release valve being provided with an orifice which allows fluid communication between said gas release valve and said chamber; and means for releasing said poisonous gas from said gas canister.

Conveniently said means for releasing said poisonous gas from said gas canister comprises a piercing member, said piercing member and said outlet means being relatively moveable towards and away from each other, and said piercing member being arranged to pierce said outlet means of said gas canister to allow poisonous gas to be released therefrom .

Preferably said means for releasing said poisonous gas from said gas canister further comprises an actuation means arranged to provide for relative movement between said piercing member and said gas canister before and after piercing of said gas canister.

Further said actuation means is also arranged to disengage said catch means from said door mechanism when said detection means detects the presence of a rodent in said trap.

In particular said actuation means comprises an electric motor.

An advantage associated with a motorised actuation means is that the triggering of the trap is conducted under the control of the motor. Controlling the triggering of a rodent trap in such a manner eliminates the possibility of inadvertent triggering of the rodent trap, for instance in

"spring-loaded" traps where a jolt to such a trap can trigger the trap.

Advantageously said housing comprises locating means configured to receive said gas canister and to prevent closure of said housing if said gas canister is incorrectly located.

According to another aspect of the present invention there is provided a rodent trap triggering arrangement for use in relation to a rodent trap comprising a gas canister and operable to initiate relative movement between a piercing member and the gas canister for the release of gas from the canister into a chamber of the rodent trap, the triggering arrangement further being arranged to activate closure means for the chamber. Preferably said triggering arrangement member further comprises a gas release valve having an inlet means arranged to engage with a gas canister, said gas release valve being provided with an orifice which allows fluid communication between said gas release valve and a chamber of a rodent trap.

In particular said piercing member is located adjacent said gas release valve.

Advantageously the means driving said relative movement is also arranged to disengage a catch means from said closure means so as to allow for the operation thereof.

If required, said actuation means comprises an electric motor.

Conveniently, said rodent trap triggering arrangement further comprises control circuitry arranged to receive signals from detectors located within said rodent trap and arranged to control operation of said rodent trap based upon signals received from said detectors.

Preferably upon release of said gas from the canister into a chamber of the rodent trap, a direction of said relative movement is reversed.

According to another aspect of the present invention there is provided a rodent trap, comprising: a gas canister operable to release a gas into a chamber of said rodent trap when pierced by a piercing member located adjacent said gas canister, said piercing member being arranged to pierce said gas canister subsequent to activation of closure means serving to block openings which provide access to said chamber, wherein a housing of said rodent trap is configured to allow opening thereof to enable a user to replace said gas canister, and said housing is provided with locating means serving to prevent closure of said housing if a gas canister is incorrectly located. Preferably said housing is formed with first and second openings providing access to said chamber located within said housing.

Said rodent trap can further comprise first and second detection means adjacent said openings respectively, and arranged to detect the presence of a rodent.

In particular said rodent trap further comprises timing means arranged to be initiated when one of said detection means detects the presence of a rodent.

Advantageously said rodent trap further comprises first and second closure means associated with said first and second openings respectively and arranged to be triggered by way of detection means to prevent escape from said chamber, said closure means being arranged to be triggered when both said first and second detection means detect the presence of a rodent, within a period as determined by said timing means.

If required said locating means comprises a recess formed in an underside of an upper housing portion of said housing.

According to a further aspect of the present invention there is provided a rodent trap, comprising: a housing having first and second openings providing access to a chamber located within said housing; detection means arranged to detect the presence of a rodent within the chamber; first and second closure means associated with said first and second openings respectively and arranged to prevent escape from said chamber upon detection of a rodent within said chamber by said detection means; gas supply means arranged to release gas into said chamber when a rodent is trapped therein, and including a gas flow regulator arranged to provide a predetermined gas release rate into said chamber in order to maintain a gas concentration level within said chamber at a level sufficient to overwhelm said rodent. According to another aspect of the present invention there is provided a resilient catch release mechanism comprising: a rotor provided with teeth on a peripheral edge thereof; a latch member having an opening therein presenting a surface with a toothed portion for engagement with the teeth of said rotor; a movable catch member; biasing means arranged to act upon said catch member in a biasing direction and to cause said catch member to abut said latch thereby preventing further movement of the catch in the biasing direction, said abutment causing the teeth of the said toothed portion of the latch to mesh with the teeth of the rotor such that rotation of said rotor causes movement of said latch from abutment with said catch member so as to release said catch member to move in the biasing direction, and so as to allow for disengagement of said teeth of the said toothed portion of the latch from the teeth of the rotor, so as to allow relative movement therebetween.

Preferably, said opening comprises a recess.

Further, said recess is substantially circular with a radius greater than that of said rotor.

Alternatively, said opening comprises an aperture.

If required, said aperture is substantially circular with a radius greater than that of said rotor.

Conveniently, said catch member is movable in a pivoting manner.

Preferably said latch comprises a cam member.

If required said catch member comprises a cam follower.

Conveniently said biasing means comprises a beam torsion spring.

Alternatively said biasing means comprises a spiral spring. in a further alternative said biasing means comprises a compression spring.

In another alternative said biasing means comprises a tension spring.

The present invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which:

Fig. 1a illustrates a first perspective view of a rodent trap in an untriggered state according to the present invention;

Fig. 1b illustrates a first perspective view of a rodent trap in a triggered state according to the present invention;

Fig. 2a illustrates a second perspective view of a rodent trap in an untriggered state according to the present invention;

Fig. 2b illustrates a second perspective view of a rodent trap in a triggered state according to the present invention;

Fig. 3a illustrates a perspective view of a rodent trap in an open, untriggered state according to the present invention;

Fig. 3b illustrates a perspective view of a rodent trap in an open, triggered state according to the present invention;

Fig. 4a illustrates a cross-sectional side view of the rodent trap of Fig. 2a viewed in the direction A-A;

Fig. 4b illustrates a cross-sectional side view of the rodent trap of Fig. 2b viewed in the direction B-B; Fig. 5a illustrates a side view of operational parts of a rodent trap in an untriggered state according to the present invention;

Fig. 5b illustrates the rodent trap of Fig. 5a with a cutter means housing removed;

Fig. 6a illustrates a perspective view of the operational parts of Fig. 5a;

Fig. 6b illustrates a cross-sectional side view of the rodent trap of Fig. 6a viewed in the direction C-C;

Fig. 6c illustrates a cross-sectional side view of the rodent trap of Fig. 2a viewed in the direction D-D;

Fig. 7a illustrates a side view of operational parts of a rodent trap in a triggered state according to the present invention;

Fig. 7b illustrates the rodent trap of Fig. 7a with a cutter means housing removed;

Fig. 8a illustrates a perspective view of the operational parts of Fig. 7a;

Fig. 8b illustrates a cross-sectional side view of the rodent trap of Fig. 8a viewed in the direction E-E;

Fig. 8c illustrates a cross-sectional side view of the rodent trap of Fig, 2b viewed in the direction F-F; and

Figs. 9a-9f illustrate cross-sectional side views of a locking mechanism suitable for controlling operation of doors, and particularly suitable for controlling the operation of rodent trap doors in the present invention.

As mentioned, Fig. 1 illustrates a rodent trap 10 in an untriggered state. The rodent trap 10 comprises a generally elongate housing 12 which is formed from an upper housing portion 14a and a lower housing portion 14b. Upper and lower housing portions 14a, 14b are connected by means of a hinge arrangement 16 provided in the region of adjacent longitudinal edges of the housing portions 14a, 14b. With such a configuration, the upper housing portion 14a and lower housing portion 14b combine to resemblea "clam-shell" which is elongate in the direction of the hinge. The provision of said hinge 16 allows said housing 12 to be opened to gain access to the interior thereof.

The contacting edges of said upper and lower housing portions 14a, 14b are arranged such that when the rodent trap 10 is in a closed condition, such edges are in sealing engagement with one another.

At opposing end faces of the housing 12, there is located a first opening 18a and a second opening (not shown - see Fig. 2a) which are in communication and provide access to a chamber 20 located within said housing 12. The first opening 18a and the second opening allow a rodent to access the chamber 20 of said rodent trap 10.

The rodent trap of Fig. 1a is shown (as mentioned above) in an untriggered state, i.e. closure means (not shown) of said rodent trap 10 are in an open position thereby allowing a rodent to enter/exit the chamber by way of the first opening 18a.

However, Fig. 1b illustrates the rodent trap 10 of the present invention in a triggered state. The features illustrated in Fig. 1 b which correspond to features already described are denoted by like reference numerals and so are not discussed further.

When said rodent trap 10 is in said triggered state, closure means serve to cover said first opening 18a and said second opening (not shown) in order to prevent a rodent trapped within the rodent trap 10 from escaping. Fig. 1b illustrates first closure means 22a in a closed position serving to cover said first opening 18a. A corresponding second closure means (not shown) is located at an opposing end of said rodent trap 10 and serves to cover said second opening (not shown).

The perspective view of Fig. 2a illustrates the rodent trap 10 (i.e. in an untriggered state) as viewed from an opposite direction. Again, the features in Fig. 2a which correspond to features already described are denoted by like reference numerals and will not be discussed further.

In this alternative view of the rodent trap of Fig. 1a, second opening 18b can be seen. As discussed above, the second opening 18b is located at an opposite end to the first opening 18a and so the second opening 18b provides access to the chamber 20 from an opposite end to first opening 18a.

The upper housing portion 14a is provided with first and second locking means 24a, 24b which are located adjacent the longitudinal edge of said upper housing portion 14a remote from said hinge 16. Such first and second locking means 24a, 24b are arranged to engage with corresponding holes for receiving said locking means (not shown) located in said lower housing portion 14b in order to prevent opening of said housing 12, The first and second locking means 24a, 24b are configured to receive a key 26 which is arranged to lock/unlock said housing 12.

In the illustrated embodiment, the first and second locking means 24a, 24b are located adjacent the ends of said housing 12, but in alternative arrangements, there may be any number of locking means located at any position on the housing 12. Also, in the illustrated embodiment, the first and second locking means 24a, 24b are located in said upper housing portion 14a, and the holes for receiving said locking means are located in said lower housing portion 14b. However, in an alternative arrangement, these positions may be reversed. Of course, other types of suitable locking arrangements will be evident to the person skilled in the art. Also illustrated in Fig. 2a is a display means 28 located in said upper housing portion 14a which serves to inform an operator of the condition of said rodent trap (e.g. untriggered state, triggered state, fault, etc.). The display means 28 comprises a Light Emitting Diode (LED), which is arranged to convey necessary information by means of different combinations of pulses or colours. Of course, in alternative arrangements, the display means 28 may comprise a Liquid Crystal Display (LCD) or may be used in combination with (or be replaced with) a device to convey said information audibly, or may comprise any suitable means for conveying such information to an operator.

Fig. 2b illustrates the rodent trap 10 of the present invention in the same view as that of Fig. 2a, but in this figure the rodent trap 10 is in a triggered state. As such, the second closure means 22b can be seen covering second opening 18b.

Fig. 3a illustrates the rodent trap 10 as viewed from the same angle as in Fig. 2a, but illustrates the internal features of the rodent trap 10 in a condition opened about its hinge arrangement 16.

Fig. 3a clearly illustrates many of the operational parts of the rodent trap 10 of the present invention, the illustrated operational parts comprising: first and second closure means 22a, 22b which are arranged to move from an open position (as shown in Fig. 3a when the rodent trap 10 is in an untriggered state) to a closed position where such closure means 22a, 22b operate to cover said first and second openings 18a, 18b respectively; pressure pads 32a, 32b located in a floor of said chamber 20 adjacent the first and second openings 18a, 18b respectively and arranged to detect the presence of a rodent when said rodent steps thereon; control means 34 arranged to receive a detection signal from said pressure pads 32a, 32b and operable to initiate a triggering and extermination process of said rodent trap 10; motor and gearbox 36, one operation of which involves the release of the said first and second closure means 22a, 22b from said open position to a closed position in response to a control signal received from said control means 34; a motor mounting plate 38 which is arranged to connect said motor and gearbox 36 with a cutter means housing 40; a gas release block 42 located at an end of said cutter means housing 40 remote from said motor mounting plate 38 and being open at an end thereof remote from said motor mounting plate 38; and a gas canister 44, an outlet end of which is engageable with said open end of said gas release block 42.

The operational parts of the rodent trap 10 (apart from pressure pads 32a, 32b) are arranged in a longitudinal manner along one side of said housing

12 adjacent to said chamber 20. In the illustrated embodiment, the operational parts of the rodent trap 10 are located in the lower housing portion 14b along the side of the lower housing portion 14b remote from said hinge 16.

Fig. 3a also illustrates holes 30a, 30b which are provided in said lower housing portion 14b and which are configured to receive said locking means 24a, 24b. Thus, when said rodent trap 10 is in a closed condition, locking means 24a, 24b are received in holes 30a, 30b respectively and said rodent trap 10 can be locked by using key 26 to rotate said locking means 24a, 24b to engage with locking features (not shown) located in said holes 30a, 30b.

In the present embodiment the gas canister 44 has a neck portion (not shown) at the outlet end thereof, and which is provided with a screw thread such that it can be received in a threaded open end of said gas release block 42 for releasable engagement therewith.

The upper housing portion 14a is provided with a locating means 46 which is configured to engage and/or receive said gas canister 44 when said rodent trap 10 is in said closed condition. The locating means 46 is arranged to prevent closing of the trap if the gas canister 44 is incorrectly engaged with said gas release block 42, and so requires full threaded engagement of the gas canister 44 and gas release block 42 before closure of the trap is possible.

Fig. 3b illustrates the rodent trap 10 of the present invention in the same view as that of Fig. 3a, but in a triggered state. As such, the first and second closure means 22a, 22b can be seen covering said first and second openings respectively.

Fig. 4a illustrates a cross-sectional side view of the rodent trap of Fig. 2a viewed in the direction A-A and features in this figure which correspond to features already described are denoted by like reference numerals and will not be discussed further.

Here there is illustrated a locking mechanism controllable by said motor and gearbox 36 and which is arranged to lock the first closure means 22a and second closure means (not shown) in an open state when the rodent trap 10 is in said untriggered state. Upon operation of said motor and gearbox 36, the locking mechanism is operable to release said first closure means 22a and second closure means to trigger said rodent trap 10 such that said first and second closure means move to their closed state.

The locking mechanism is spaced from said motor mounting plate 38 by means of a spacer 48 (the function of which will be discussed later). A rotor 50 is mounted upon a rotatable shaft 52 which extends from motor and gearbox 36 and which is rotatable under the control of said motor and gearbox 36. Said rotor 50 is generally cylindrical in shape and is coaxially mounted upon said shaft 52. The curved surface of said rotor 50 is provided with teeth, the peaks and troughs of which are oriented parallel with an axis of said rotor 50.

The locking mechanism further comprises a latch 54 which is in the form of a cam. The latch 54 is mounted coaxially upon said rotor 50 and is provided with teeth over part of a meshing surface thereof. Such teeth are arranged to engage with the teeth of said rotor. However, as stated above, the meshing surface of said latch 54 is only provided with teeth over some of its surface. When the rodent trap 10 is in the untriggered state in a normal orientation, the latch 54 is arranged such that the cam depends from said shaft 52. The teeth of the meshing surface of said latch 54 upstand from the meshing surface in this configuration to engage with the teeth at the portion of the rotor 50 facing downwards. The remaining meshing surface of the latch 54 is smooth and does not engage with the rotor 50. The teeth of said latch 54 are urged into meshing engagement with the teeth of the rotor 50 by means of door release catch 56. Door release catch 56 comprises a cam follower which is biased in an upwards direction and acts upon a tip of said cam forming said latch 54 to urge the teeth of the latch 54 into such engagement with the teeth of the rotor 50. The operation of the locking mechanism is described briefly below and will be described in more detail later in relation to Figs. 9a to 9f.

Door release catch 56 is mounted upon door beam 58 which comprises a rod arranged longitudinally in said rodent trap 10. The ends of the rod forming door beam 58 are received in end walls of said lower housing portion 14b, and said door beam is arranged to rotate about its longitudinal axis. Mounted at each end of door beam 58 are said first closure means

22a and said second closure means (not shown) which, in the illustrated embodiment, are in the form of doors. Thus, the first and second closure means are arranged to pivot from said open position to said closed position (and back) with the rotation of said door beam 58. A beam torsion spring (not shown) is located adjacent to said door beam 58 and is arranged with an axis thereof parallel to the longitudinal axis of said door beam 58. Each end of said beam torsion spring abuts with an edge of said first and second closure means respectively and is arranged to urge said first and second closure means to said closed position. Such biasing causes said door release catch 56 which is mounted upon said door beam

58, extends therefrom and thus is pivotable thereabout, to provide an upward biasing force. A tip of said door release catch 56 which abuts the tip of said cam forming said latch 54 is thus urged upwards by the action of said beam torsion spring (not shown). Therefore, the door release catch 56 exerts an upwardly directed force on said latch 54 and said latch 54 exerts a downwardly directed force on said door release catch 56. When the door release catch 56 abuts the latch 54 in such a manner, any further upward pivoting motion is prevented and so the first and second closure means are effectively "locked" into the open position.

When the presence of a rodent is detected, shaft 52 rotates through the action of said motor and gearbox 36. The rotor 50 rotates with said shaft 52 and (through engagement of the teeth of the latch 54 with those of the rotor 50) the latch 54 also rotates. As the latch 54 rotates it will eventually no longer abut the tip of said door release catch 56 and two events will occur: (i) since the door release catch 56 is free to pivot and thus the door beam 58 is free to rotate, the beam torsion spring (not shown) forces said first and second closure means to the closed position; and (ii) the teeth of the latch 54 will no longer engage with those of the rotor 50 because the force urging the two sets of teeth into engagement has been removed, and so the non-meshing surface of the latch 54 will now rest upon the top of the rotor 50 and the latch 54 will be freely moveable about said rotor 50 such that the tip of the latch 54 will return, under the action of gravity, to its downwardly facing position.

Fig. 4b illustrates a cross-sectional side view of the rodent trap of Fig. 2b viewed in the direction B-B. However, it illustrates a similar view to that of Fig. 4a and merely differs in that the rodent trap 10 is illustrated in a triggered state.

As can be seen from Fig. 4b, the door release catch 58 does not abut the latch 54, and the latch hangs freely from the rotor 50.

In Fig. 5a there are illustrated the major operational parts of the rodent trap. Such operational parts of the rodent trap are illustrated in side view with the housing of the rodent trap removed to aid clarity. As stated above, the rodent trap is in an untriggered state and so the first and second closure means 22a, 22b are in the open positions. The first and second closure means 22a, 22b are mounted at opposite ends of said door beam 58, the ends of which are arranged to be received in the end faces of said lower housing portion 14b to allow the door beam 58 to rotate about its longitudinal axis. Such an arrangement allows said first and second closure means 22a, 22b to pivot between the open and closed positions. The beam torsion spring 60 is located parallel with said door beam 58 and arranged to act upon said first and second closure means 22a, 22b to urge such closure means to the closed position.

Of course, it will be apparent to the person skilled in the art that other suitable means may be used to perform the same function as the beam torsion spring 58, e.g. compression or tension helical springs, etc.

There is also illustrated gas outlet orifice 62 formed in said gas release block 42. The gas outlet orifice 62 is configured to release gas received in said gas release block 42 from said gas canister 44 to said chamber of said rodent trap when the rodent trap is triggered.

Fig. 5b illustrates the operational parts of Fig. 5a but with the cutter means housing 40 and gas release block 42 removed.

A bearing 64 is located adjacent said spacer 48 and operates to allow the shaft and the associated rotor 50 to rotate freely. At an end of said shaft remote from the motor and gearbox 36 there is provided a cylindrical cutter 66 including a piercing blade which comprises a section of said shaft which narrows to a pointed tip. The cylindrical cutter 66 is arranged to move reciprocally in a longitudinal direction coaxial with said shaft and such motion is controlled by the operation of said motor and gearbox 36. The means by which rotational movement of said motor and gearbox 36 is translated to a longitudinal movement of said cylindrical cutter 66 will described in relation to a later figure. Here there is further illustrated a neck portion 68 of said gas canister 44 which is provided with a screw thread 70 for releasable engagement with a corresponding screw thread provided within said gas release block (not shown).

The rodent trap is also shown here in an untriggered state and the tip of the cylindrical cutter 66 is located adjacent an end face of the neck portion 68 of said gas canister 44. However, when rodent trap is triggered, the cylindrical cutter 66 moves longitudinally toward the end face of the neck portion 68 of the gas canister 44 and eventually the pointed tip of the cylindrical cutter 66 will pierce the gas canister 44 causing gas to be released therefrom.

In Fig. 6a, the operational parts of the rodent trap as illustrated previously in Fig. 5a are now illustrated in a perspective view and, in addition, pressure pads 32a, 32b are shown in their relative positions. Again, the housing of the rodent trap is not shown to aid clarity.

Fig. 6b illustrates a cross-sectional side view of the rodent trap of Fig. 6a viewed in the direction C-C. Those features in Fig. 6b which correspond to features already described are denoted by like reference numerals and will not be discussed further.

A captive nut 72 is located within said cutter means housing 40 and is connected to said shaft 52. An end of said cylindrical cutter 66 remote from the pointed tip (i.e. the end of the cylindrical cutter 66 closest to the motor and gearbox 36) is arranged for reception within said captive nut 72. This end of the cylindrical cutter 66 comprises a threaded shaft which is received within a corresponding thread formed in said captive nut 72. A mid-section of said cylindrical cutter 66 comprises a square shaft arranged to sit within guides in said cutter means housing 40 which prevent rotation of said cylindrical cutter 66 with rotation of said shaft 52. As a result, as the shaft/captive nut assembly rotates, such motion is translated to a longitudinal movement of the cylindrical cutter 66. Of course, the direction of travel of the cylindrical cutter 66 (i.e. towards/away from the gas canister 44) will depend on the direction of rotation of the shaft /captive nut assembly and, ultimately, the direction of rotation of the motor and gearbox 36.

A cutter seal 74 is provided within said cutter means housing 40 and is mounted around the shaft of said cylindrical cutter 66. The cutter seal 74 is arranged to prevent gas escaping from said gas release block 42 into the body of the operational mechanism. In the illustrated embodiment the cutter seal 74 is preferably an "O-ring" seal, but alternative seals will, of course, be apparent to a person skilled in the art.

An additional seal is also provided in the gas release block 42. This gas canister seal 76 is located on an innermost face of the gas release block and is arranged to abut (and form a gas-tight seal with) an end of said gas canister 44 when the gas canister 44 is engaged with the gas release block 42. This seal prevents gas from escaping from the gas release block 42 between the threaded internal surface of the gas release block 42 and the threaded surface 70 of the gas canister 44.

Fig. 6c illustrates a cross-sectional side view of the rodent trap of Fig. 2a viewed in the direction D-D. In this figure, the operational part of the rodent trap 10 is shown in-situ in the housing 12 of the rodent trapiO.

The operational parts of the rodent trap as illustrated in Fig. 7a are identical to those previously identified in Fig. 5a, This figure merely differs in that the operational parts are shown in a triggered state of the rodent trap.

Fig. 7b illustrates the same operational parts as Fig. 7a but with the cutter means housing 40 and gas release block 42 removed. In this figure, the pointed tip of the cylindrical cutter 66 has pierced the end of the gas canister 44 and is hidden within the neck portion 68 of said gas canister 44. In Fig. 8a, the operational parts of the rodent trap as illustrated previously in Fig. 7a are now illustrated in a perspective view and, in addition, pressure pads 32a, 32b are shown in their relative positions. Again, the housing of the rodent trap is not shown to aid clarity.

The cross-sectional side view of Fig. 8b (viewed along the line E-E of Fig. 8a) illustrates the operational parts of the rodent trap when in a triggered state. This figure is similar to Fig. 6b and differs only in that the first and second closure means 22a, 22b are shown in the closed position, and in that the tip of the cylindrical cutter 66 has pierced the end of the gas canister 44 and is located in the neck portion 68 of the gas canister 44.

Gas (which is stored under pressure in the gas canister 44) is allowed to escape from a hole produced when the cylindrical cutter 66 pierces the end of the gas canister 44. Such escaping gas fills a chamber within said gas release block 42 and is vented from the gas release block 42 by way of gas outlet orifice 62. The gas outlet orifice 62 is arranged in fluid communication with said chamber (not shown) of the rodent trap such that ejected gas 78 can disperse within the chamber.

Fig. 8c illustrates a cross-sectional side view of the rodent trap of Fig. 2b viewed in the direction F-F. In this figure, the operational part of the rodent trap 10 is shown in-situ in the housing 12 of the rodent trapiO.

A description of the operation of the rodent trap 10 will now follow under numbered steps and shall commence from an already triggered state of the rodent trap 10,

(i) A key 26 is used to unlock said locking means 24a, 24b located in the upper housing portion 14a of the rodent trap 10. (ii) The housing 12 is free for opening by said operator and is opened by lifting said upper housing portion 14a from the lower housing portion 14b and allowing the two parts of the housing to open about said hinge 16. (iii) A rodent located within the chamber 20 of the rodent trap 10 and which triggered the previous operation of the rodent trap 10 is removed for later disposal by the operator.

(iv) The old gas canister 44 (i.e. the "spent" canister) is unscrewed from the gas release block 42 and removed for disposal, (v) The rodent trap 10 is set by pulling the first and second closure means 22a, 22b upwards. The rotation of the first and second closure means 22a, 22b about their pivot point (i.e. the door beam

58) to the open position will also cause rotation of said door beam 58 about its longitudinal axis. The rotation of the door beam 58 in turn causes rotation of the door release catch 56 from its upstanding position. As the door release catch 56 pivots around it eventually comes into contact with the latch 54 which is freely hanging from rotor 50. As the door release catch 56 pivots further it will push the latch 54 away from it thus causing the latch to begin to pivot about rotor 50. As the rotation continues the door release catch 56 will eventually be extending in a substantially horizontal direction and will allow the latch 54 to rotate about the shaft 50 in the opposite direction to which it was pushed and so the tip of the latch 54 will fall under gravity back to its start position such that the latch 54 hangs from the rotor 50. Upon release of the closure means 22a, 22b by the operator, the beam torsion spring 60 acts to urge the closure means 22a, 22b to the closed position and, as a result, the tip of the door release catch 56 will come into contact with the tip of the latch 54 and urge the latch 54 upwards such that the teeth provided in the latch 54 move into engagement with the teeth provided around said rotor 50. The tip of the door release catch 56 abuts the tip of the latch 54 and further movement of the door release catch 56 is thereby prevented. Such abutment of latch 54 and door release catch 56 acts to "lock" the first and second closure means 22a, 22b in the open position, (vi) A new gas canister 44 is screwed into the gas release block 42. (vii) The housing 12 of the rodent trap 10 is closed and locked, (viii) When a rodent enters the chamber 20 of the rodent trap 10 via either of said openings 18a, 18b, its presence is detected by the pressure pads 32a, 32b. In the present embodiment, the pressure pads 32a, 32b are arranged to send a detection signal to said control means 34 only when the rodent touches both pressure pads 32a, 32b within 15 seconds. Upon this condition being met, the pressure pads 32a, 32b send a detection signal to said control means 34 which, in turn, activates said motor and gearbox 36.The shaft 52 rotates under the action of the motor and gearbox 36 to which it is connected. Such rotation causes rotation of the rotor 50 which is mounted upon the shaft 52 and sits within bearing 64. The spacer 48 is provided to ensure that the bearing/rotor assembly is held in the correct position. This timing arrangement ensures that the rodent is entirely within the chamber 20 before the trap is triggered.

(ix) The rotation of the rotor 50 drives (by means of its teeth meshing with those of the latch 54) the latch 54 and causes the latch 54 to rotate. As the latch 54 rotates it moves from abutment with the door release catch 56 and thereby releases said door release catch 56.

(x) With the release of the mechanism which was constraining it, the beam torsion spring 60 is then free to cause the first and second closure means 22a, 22b and the door beam 58 to rotate, and so the first and second means 22a, 22b move to their closed positions and serve to cover the openings 18a, 18b of the rodent trap 10 thereby preventing the rodent from escaping,

(xi) The motor and gearbox 36 continue to drive the rotor 50 around which, in turn, drives the rotation of the captive nut 72 attached thereto. As described above, the end of the cylindrical cutter 66 closest to said motor and gearbox 36 comprises a threaded shaft which engages with a threaded bore of said captive nut 72. The mid-portion of the cylindrical cutter 66 comprises a square shaft which is arranged to sit within guides located in the cutter means housing 40 which are arranged to prevent said cylindrical cutter 66 from rotating. As the captive nut 72 rotates, this motion is translated (by means of the respective threads) to a longitudinal motion of the cylindrical cutter 66 towards the end of the gas canister 44. (xii) The cylindrical cutter 66 is driven through the chamber in the gas release block 42 and a pointed tip thereof eventually pierces the end of the gas canister 44 connected to the gas release block, (xiii) Gas escapes into the chamber within the gas release block from the hole formed in the end of the gas canister 44 by means of the pointed tip of the cylindrical cutter 66. (xiv) Cylindrical cutter 66 continues to be driven into the gas canister 44 until the shaft of the cylindrical cutter 66 abuts a stall plate (not shown in the figures). When such contact has been made, the motor stalls and power to it is cut. (xv) The gas released into the chamber of the gas release block 42 exits this chamber by means of gas outlet orifice 62 and fills chamber 20, thus raising the gas concentration level within the chamber to the desired level (i.e. to a level suitable to overwhelm and exterminate the trapped rodent). The rate of gas release from the gas outlet orifice 62 is dependent upon a number of factors, e.g. pressure at which gas is stored in the gas canister 44, etc., but is most importantly controlled by the shape of the gas outlet orifice 62. (xvi) Once the gas has been expelled from gas canister 44, the motor and gearbox 36 are reversed and the cylindrical cutter 66 is drawn backwards out of the cylinder. An important feature of the locking mechanism which allows this reverse rotation is in the provision of teeth only over part of the inner peripheral surface of the latch 54. As soon as the latch 54 is no longer in abutment with the door release catch 56, the teeth of the latch 54 fall from engagement with those of the rotor 50 and the latch 54 hangs freely from the rotor 50. Thus, reverse rotation of the rotor 50 is possible because its teeth are no longer in engagement with those of the latch 54. (xvii) The display means 28 located in said housing 12 displays that the rodent trap 10 has been triggered and can be arranged to display an "all-clear" signal when the extermination process has been completed. At this stage, the operator can then open the rodent trap 10 and the above steps of the operation can be repeated.

Figs. 9a-9f illustrate cross-sectional side views of a locking mechanism suitable for controlling operation of doors, and particularly suitable for controlling the operation of rodent trap closure means in the present invention. Reference numerals corresponding to those used previously for the various components comprising the closure means locking mechanism will be used in the subsequent description of this door locking mechanism.

Fig. 9a illustrates a locking mechanism 78 in a "locked" position and which comprises a rotor 50 mounted upon a shaft 52 and arranged to rotate with rotation of said shaft 52. The rotor 52 is provided with teeth 80 in a peripheral edge thereof. The locking mechanism 78 further comprises a latch 54 and a door release catch 56 mounted on a door beam 58. The configuration and operation of the locking mechanism 78 correspond to the locking mechanism as described above as a feature of said rodent trap.

In Fig. 9b, the shaft 52 is shown rotating in a clockwise direction as denoted by arrow A1. The rotor 50 also rotates in the same direction as the shaft 52. The meshing of the teeth of the rotor 50 with teeth 82 of the latch 54 cause the latch 54 to rotate in a direction denoted by arrow A2 (which is the same direction of rotation as the shaft 52 and rotor 50).

Eventually, and as illustrated by Fig. 9c, the latch 54 rotates such that it no longer abuts the door release catch 56, and the door release catch 56 is free to pivot under the action of the rotation of door beam 58 (and beam torsion spring (not shown)) in a direction denoted by arrow B2. The rotor 50 continues to rotate in a direction denoted by arrow A1 and, because the door release catch 56 no longer provides an upwardly acting force on the latch 54 the teeth 82 thereof are caused to disengage from those teeth 80 of the rotor 50, and so the latch 54 is free to rotate about said rotor 50 and rotates (under the action of gravity) in a direction denoted by arrow B1. As the rotor 50 is no longer in meshing engagement with the latch 54 it is free to rotate in an opposite direction denoted by arrow C1 as shown in Fig. 9d.

Figs. 9e and 9f relate to a "locking" action of said locking mechanism 78 and, in Fig. 9e the door release catch 56 is illustrated being urged back to its start position (i.e. such that it extends substantially horizontally from said door beam 58). This direction of rotation to urge said door release catch 56 to its start position is denoted by means of arrow D2. As the door release catch 56 rotates, its tip will push against an end of said latch 54 and thus cause said latch to rotate about said rotor 50 in a direction denoted by arrow D1. When the door release catch 56 reaches the substantially horizontal position, the latch 54 is allowed to rotate in a direction denoted by arrow E1 under the action of gravity back to a position where it hangs substantially vertically from said rotor 50. Release of the door release catch 56 at this point will allow the door release catch 56 to rotate slightly in a clockwise direction as denoted by arrow E2. The tip of the door release catch 56 will be caused to abut the tip of the latch 54 and thus force the latch 54 upwards such that its teeth 82 engage with those teeth 80 of the rotor 50. The locking mechanism is thus returned to its

"locked" position.

In the above described embodiment of the rodent trap, the described means for detecting the presence of a rodent within the chamber of the rodent trap relates to pressure pads. However, in an alternative embodiment, the pressure pads may be replaced by electro-optical detection means for detecting the presence of a rodent within the trap. In particular, such electro-optical detection means may be an infra-red emitter and detector which are operable to send a detection signal to said control means when an infra-red beam emitted by said emitter and received by said detector is broken by the passage of a rodent therethrough. The use of pressure pads in the present invention provides for selective triggering of said rodent trap. The pressure pads can be set to cause a detection signal to be sent to said control means only when a rodent greater than a certain weight (e.g. >70 grams) passes over said pressure pads. Thus, the trap will not be inadvertently triggered by, for instance, a small bird which enters the trap.

In the above embodiment the overall length of the chamber of the rodent trap is 50cm. However, this length may be altered depending upon the type of rodent which is to be trapped using the above described apparatus.

In the above embodiment it is specified that the rodent must touch both pressure pads within 15 seconds for the trap to be triggered. However, a different time delay may be incorporated depending upon the overall length of the trap and/or the type of rodent to be trapped and/or exterminated.

The type of gas used in the gas canister in the above described rodent trap is carbon-dioxide (CO2). Of course, any other type of gas (e.g. carbon- monoxide or nitrogen) which is suitable in overwhelming and exterminating rodents may be used.

The above disclosed rodent trap is arranged to provide a gas concentration of at least 80% gas within said chamber, and for such a concentration to be sustained for at least two minutes in order to overwhelm and exterminate a rodent trapped therein. However, other gas concentrations and periods for which such concentrations are sustained will be evident to those skilled in the art.

In the above embodiment, the first and second closure means may be provided with chamfered leading edges which allow said closure means to easily slot into recesses around said first and second openings respectively when the first and second closure means move to said closed position. Such chamfered edges provide a "self-finding" mechanism for said closure means.

The rodent trap of the present invention may also be provided with inclined floor sections in the bottom of said chamber arranged such that the floor inclines towards the centre of the chamber from each end. Such a feature will allow any water (or other liquid) which enters said chamber (e.g. when the device is used in an outdoor environment) to drain from said chamber by running towards said openings and draining therethrough, or through holes formed in the floor of said chamber adjacent said openings.

The rodent trap of the present invention may, in an alternative arrangement, also be provided with fixing means to allow said rodent trap to be fixed to the ground.

In a further alternative arrangement, the gas canister may be moved towards a stationary cutter means to cause piercing thereof.

In yet another alternative arrangement, the rodent trap is not configured to exterminate a rodent and merely serves to trap said rodent

Alternatively, the motor and gearbox are replaced with suitable means for controlling the locking/unlocking of the closure means, and a solenoid having a sharpened end which is arranged to pierce the gas canister under control of said control means.

In another alternative arrangement, the gas canister may be replaced with a piston driven gas supply means of which the piston is operable under the influence of the motor and gearbox.

In an illustrative example of the present invention, said orifice of said gas release valve is configured to allow a gas flow rate of between 5 litres/ minute and 40 litres/minute. Such a flow rate is affected by a number of factors relating to the characteristics of the orifice. In one particular illustrative example, the diameter of the orifice may be between 0.1mm and 1mm.

Claims

1. A rodent trap, comprising: a housing having first and second openings providing access to a chamber located within said housing; first and second detection means adjacent said openings respectively, and arranged to detect the presence of a rodent; timing means arranged to be initiated when one of said detection means detects the presence of a rodent; first and second closure means associated with said first and second openings respectively and arranged to be triggered by way of the detection means to prevent escape from said chamber, said closure means being arranged to be triggered when both said first and second detection means detect the presence of a rodent, within a period as determined by said timing means; the trap being arranged to receive extermination means operable to exterminate said rodent subsequent to activation of said closure means.

2. A rodent trap according to Claim 1, wherein said housing is configured to allow opening thereof.

3. A rodent trap according to Claim 2, wherein said housing comprises a base portion and a lid portion, said lid portion and base portion arranged to cooperate to enclose a volume which forms said chamber.

4. A rodent trap according to Claim 3, wherein said lid portion and base portion are hingedly attached to each other.

5. A rodent trap according to Claim 3 or Claim 4, wherein edges of contact between said base portion and lid portion are provided with a sealing member to form a seal between the base portion and lid portion of said housing when the housing is in a closed state.

6. A rodent trap according to any one or more of the preceding claims, wherein said first and second detection means comprise electro-optic detection means.

7. A rodent trap according to Claim 6, wherein said electro-optic detection means comprises an infrared detection means.

8. A rodent trap according to any one or more of Claims 1 to 5, wherein said first and second detection means comprise a pressure sensor arranged to output a detection signal when a rodent exerts pressure thereon.

9. A rodent trap according to Claim 8, wherein said pressure sensor is arranged to output said detection signal only when a pressure equivalent to a rodent weight of >70 grams is exerted on said pressure sensor.

10. A rodent trap according to any one or more of the preceding claims, wherein said first and second closure means comprise a door mechanism comprising first and second doors moveable between an open position thereby allowing a rodent access to said chamber by means of said openings, and a closed position where said openings are blocked and escape from said chamber is prevented.

11. A rodent trap according to Claim 10, wherein said doors are pivotable between said open and closed positions about an axis perpendicular to the plane of said doors.

12. A rodent trap according to Claim 10 or Claim 11 , and further comprising a catch means arranged to act upon said door mechanism to retain said doors in said open position when said rodent trap is in an untriggered state.

13. A rodent trap according to Claim 12, wherein said catch means is arranged to disengage from said door mechanism to release said doors, thereby allowing them to move to said closed position, when said detection means detects the presence of a rodent in said trap.

14. A rodent trap according to any one or more of Claims 10 to 13, wherein said door mechanism further comprises a rod connected to said doors and extending therebetween along the length of said housing, said rod defining an axis about which the doors are arranged to pivot.

15. A rodent trap according to Claim 14, wherein said catch means is arranged to engage with said rod to retain said doors in an open position in said untriggered state of said trap, and to disengage said rod to allow said doors to move to said closed position when said detection means detects the presence of a rodent in said trap.

16. A rodent trap according to any one or more of Claims 10 to 15, further comprising biasing means arranged to urge said doors to said closed position.

17. A rodent trap according to Claim 16, wherein said biasing means comprises a beam torsion spring.

18. A rodent trap according to Claim 16, wherein said biasing means comprises a spiral spring.

19. A rodent trap according to Claim 16, wherein said biasing means comprises a compression spring.

20. A rodent trap according to Claim 16, wherein said biasing means comprises a tension spring.

21. A rodent trap according to any one or more of Claims 10 to 20, wherein peripheral edges of said doors are configured to form a seal between the peripheral edges thereof and the periphery of said openings when said doors are in said closed position.

22. A rodent trap according to any one or more of the preceding claims, wherein said extermination means comprises electrical means operable to electrocute a rodent trapped in said trap.

23. A rodent trap according to any one or more of Claims 1 to 21 , wherein said extermination means comprises a source of poisonous gas.

24. A rodent trap according to Claims 23, wherein said extermination means further comprises a means arranged to introduce said poisonous gas into said chamber.

25. A rodent trap according to Claim 24, and arranged to receive a gas canister for the storage of said poisonous gas.

26. A rodent trap according to Claim 25, wherein said means arranged to introduce poisonous gas into said chamber comprises: a gas release valve having an inlet means arranged to engage with an outlet means of said gas canister, said gas release valve being provided with an orifice which allows fluid communication between said gas release valve and said chamber; and means for releasing said poisonous gas from said gas canister.

27. A rodent trap according to Claim 26, wherein said means for releasing said poisonous gas from said gas canister comprises a piercing member, said piercing member and said outlet means being relatively moveable towards and away from each other, and said piercing member being arranged to pierce said outlet means of said gas canister to allow poisonous gas to be released therefrom .

28. A rodent trap according to Claim 27, wherein said means for releasing said poisonous gas from said gas canister further comprises an actuation means arranged to provide for relative movement between said piercing member and said gas canister before and after piercing of said gas canister.

29. A rodent trap according to Claim 28, wherein said actuation means is also arranged to disengage said catch means from said door mechanism when said detection means detects the presence of a rodent in said trap.

30. A rodent trap according to Claim 28 or Claim 29, wherein said actuation means comprises an electric motor.

31. A rodent trap according to any one or more of Claims 25 to 30, wherein said housing comprises locating means configured to receive said gas canister and to prevent closure of said housing if said gas canister is incorrectly located.

32. A rodent trap triggering arrangement for use in relation to a rodent trap comprising a gas canister and operable to initiate relative movement between a piercing member and the gas canister for the release of gas from the canister into a chamber of the rodent trap, the triggering arrangement further being arranged to activate closure means for the chamber,

33. A triggering arrangement according to Claim 32, and further comprising a gas release valve having an inlet means arranged to engage with a gas canister, said gas release valve being provided with an orifice which allows fluid communication between said gas release valve and a chamber of a rodent trap.

34. A triggering arrangement according to Claim 33, wherein said piercing member is located adjacent said gas release valve.

35. A triggering arrangement according to any one or more of Claims 32 to 34 wherein the means driving said relative movement is also arranged to disengage a catch means from said closure means so as to allow for the operation thereof.

36. A triggering arrangement according to any one or more of Claims 32 to 34, wherein said actuation means comprises an electric motor.

37. A triggering arrangement according to any one of more of Claims 32 to

36, further comprising control circuitry arranged to receive signals from detectors located within said rodent trap and arranged to control operation of said rodent trap based upon signals received from said detectors.

38. A triggering arrangement according to any one or more of Claims 32 to

37, wherein upon release of said gas from the canister into a chamber of the rodent trap, a direction of said relative movement is reversed.

39. A rodent trap, comprising: a gas canister operable to release a gas into a chamber of said rodent trap when pierced by a piercing member located adjacent said gas canister, said piercing member being arranged to pierce said gas canister subsequent to activation of closure means serving to block openings which provide access to said chamber, wherein a housing of said rodent trap is configured to allow opening thereof to enable a user to replace said gas canister, and said housing is provided with locating means serving to prevent closure of said housing if a gas canister is incorrectly located.

40. A rodent trap according to Claim 39, wherein said housing is formed with first and second openings providing access to said chamber located within said housing.

41. A rodent trap according to Claim 40, further comprising first and second detection means adjacent said openings respectively, and arranged to detect the presence of a rodent.

42, A rodent trap according to Claim 37, further comprising timing means arranged to be initiated when one of said detection means detects the presence of a rodent.

43. A rodent trap according to Claim 42, comprising first and second closure means associated with said first and second openings respectively and arranged to be triggered by way of detection means to prevent escape from said chamber, said closure means being arranged to be triggered when both said first and second detection means detect the presence of a rodent, within a period as determined by said timing means.

44. A rodent trap according to any one or more of Claims 39 to 43, wherein said locating means comprises a recess formed in an underside of an upper housing portion of said housing.

45. A rodent trap, comprising: a housing having first and second openings providing access to a chamber located within said housing; detection means arranged to detect the presence of a rodent within the chamber; first and second closure means associated with said first and second openings respectively and arranged to prevent escape from said chamber upon detection of a rodent within said chamber by said detection means; gas supply means arranged to release gas into said chamber when a rodent is trapped therein, and including a gas flow regulator arranged to provide a predetermined gas release rate into said chamber in order to maintain a gas concentration level within said chamber at a level sufficient to overwhelm said rodent.

46. A rodent trap according to Claim 45, wherein said housing is configured to allow opening thereof.

47. A rodent trap according to Claim 46, wherein said housing comprises a base portion and a lid portion, said lid portion and base portion arranged to cooperate to enclose a volume which forms said chamber.

48, A rodent trap according to Claim 47, wherein said lid portion and base portion are hingedly attached to each other.

49. A rodent trap according to Claim 46 or Claim 47, wherein edges of contact between said base portion and lid portion are provided with a sealing member to form a seal between the base portion and lid portion of said housing when the housing is in a closed state.

50. A rodent trap according to any one or more of the preceding claims, wherein said first and second detection means comprise electro-optic detection means.

51. A rodent trap according to Claim 50, wherein said electro-optic detection means comprises an infrared detection means.

52. A rodent trap according to any one or more of Claims 45 to 49, wherein said first and second detection means comprise a pressure sensor arranged to output a detection signal when a rodent exerts pressure thereon.

53. A rodent trap according to Claim 52, wherein said pressure sensor is arranged to output said detection signal only when a pressure equivalent to a rodent weight of >70 grams is exerted on said pressure sensor.

54. A rodent trap according to any one or more of Claims 45 to 53, wherein said first and second closure means comprise a door mechanism comprising first and second doors moveable between an open position thereby allowing a rodent access to said chamber by means of said openings, and a closed position where said openings are blocked and escape from said chamber is prevented.

55. A rodent trap according to Claim 54, wherein said doors are pivotable between said open and closed positions about an axis perpendicular to the plane of said doors.

56. A rodent trap according to Claim 54 or Claim 55, and further comprising a catch means arranged to act upon said door mechanism to retain said doors in said open position when said rodent trap is in an untriggered state.

57. A rodent trap according to Claim 56, wherein said catch means is arranged to disengage from said door mechanism to release said doors, thereby allowing them to move to said closed position, when said detection means detects the presence of a rodent in said trap.

58. A rodent trap according to any one or more of Claims 54 to 57, wherein said door mechanism further comprises a rod connected to said doors and extending therebetween along the length of said housing, said rod defining an axis about which the doors are arranged to pivot.

59. A rodent trap according to Claim 58, wherein said catch means is arranged to engage with said rod to retain said doors in an open position in said untriggered state of said trap, and to disengage said rod to allow said doors to move to said closed position when said detection means detects the presence of a rodent in said trap.

60. A rodent trap according to any one or more of Claims 54 to 59, further comprising biasing means arranged to urge said doors to said closed position.

61. A rodent trap according to Claim 60, wherein said biasing means comprises a beam torsion spring.

62. A rodent trap according to Claim 60, wherein said biasing means comprises a spiral spring.

63. A rodent trap according to Claim 60, wherein said biasing means comprises a compression spring.

64. A rodent trap according to Claim 60, wherein said biasing means comprises a tension spring.

65. A rodent trap according to any one or more of Claims 54 to 64, wherein peripheral edges of said doors are configured to form a seal between the peripheral edges thereof and the periphery of said openings when said doors are in said closed position.

66. A rodent trap according to any one or more of Claims 45 to 65, and arranged to receive a gas canister for the storage of said gas.

67. A rodent trap according to Claim 66, wherein said gas flow regulator is arranged to engage with an outlet means of said gas canister, said gas flow regulator being provided with an orifice which allows fluid communication between said gas flow regulator and said chamber; and means for releasing said gas from said gas canister.

68. A rodent trap according to Claim 67, wherein said means for releasing said gas from said gas canister comprises a piercing member, said piercing member and said outlet means being relatively moveable towards and away from each other, and said piercing member being arranged to pierce said outlet means of said gas canister to allow gas to be released therefrom .

69. A rodent trap according to Claim 68, wherein said means for releasing said gas from said gas canister further comprises an actuation means arranged to provide for relative movement between said piercing member and said gas canister before and after piercing of said gas canister.

70. A rodent trap according to Claim 69, wherein said actuation means is also arranged to disengage said catch means from said door mechanism when said detection means detects the presence of a rodent in said trap.

71. A rodent trap according to Claim 69 or Claim 70, wherein said actuation means comprises an electric motor.

72. A rodent trap according to any one or more of Claims 66 to 71 , wherein said housing comprises locating means configured to receive said gas canister and to prevent closure of said housing if said gas canister is incorrectly located.

73. A resilient catch release mechanism comprising: a rotor provided with teeth on a peripheral edge thereof; a latch member having an opening therein presenting a surface with a toothed portion for engagement with the teeth of said rotor; a movable catch member; biasing means arranged to act upon said catch member in a biasing direction and to cause said catch member to abut said latch thereby preventing further movement of the catch in the biasing direction, said abutment causing the teeth of the said toothed portion of the latch to mesh with the teeth of the rotor such that rotation of said rotor causes movement of said latch from abutment with said catch member so as to release said catch member to move in the biasing direction, and so as to allow for disengagement of said teeth of the said toothed portion of the latch from the teeth of the rotor, so as to allow relative movement therebetween.

74. A mechanism according to Claim 73, wherein said opening comprises a recess.

75. A mechanism according to Claim 74, wherein said recess is substantially circular with a radius greater than that of said rotor.

76. A mechanism according to Claim 73, wherein said opening comprises an aperture.

77. A mechanism according to Claim 76, wherein said aperture is substantially circular with a radius greater than that of said rotor.

78. A mechanism according to any one or more of Claims 73 to 77, wherein said catch member is movable in a pivoting manner.

79. A mechanism according to any one or more of Claims 73 to 78, wherein said latch comprises a cam member.

80. A mechanism according to Claim 79, wherein said catch member comprises a cam follower.

81. A mechanism according to any one or more of Claims 73 to 80, wherein said biasing means comprises a beam torsion spring.

82. A mechanism according to any one or more of Claims 73 to 80, wherein said biasing means comprises a spiral spring.

83. A mechanism according to any one or more of Claims 73 to 80, wherein said biasing means comprises a compression spring.

84. A mechanism according to any one or more of Claims 73 to 80, wherein said biasing means comprises a tension spring.

85. A rodent trap substantially as hereinbefore described with reference to, or as illustrated in, Figures 1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b, 6c or 8c of the accompanying drawings.

86. A rodent trap triggering arrangement substantially as hereinbefore described with reference to, or as illustrated in, Figures 3a, 3b, 5a, 5b, 6a, 6b, 6c, 7a, 7b, 8a, 8b or 8c of the accompanying drawings. A resilient catch release mechanism substantially as hereinbefore described with reference to, or as illustrated in, Figures 4a, 4b, 5a, 5b, 6a, 6b, 6c_; 7a, 7b, 8a, 8b, 8c or 9a to 9f of the accompanying drawings.