Stunning device for killing small animals or fish

[0001] This invention relates to apparatus which can be used to stun, or slaughter, small animals and fish. In particular, the invention relates to pneumatically operated apparatus.

[0002] Processing of animals for food usually involves the initial slaughter of the animal. In the processing of larger animals such as cattle, this is typically done by a blow to an animal's head using a pneumatically- or cartridge-powered gun with a captive bolt or piston in place of a projectile.

[0003] Processing of some fishes also requires slaughter as an initial step in the process. For example, salmon are typically “stunned” by a blow to the head before processing as food. In many instances, the blow is applied with a simple club, there being no readily available apparatus for the procedure. Smaller animals such as rabbits are similarly stunned by a blow to the head, there again being no readily available apparatus suitable for use with animals of this size.

[0004] Any apparatus must be capable of delivering a blow to the head of an animal or fish in such a way that stunning can be done humanely. For most processing needs, the apparatus must also be capable of delivering blows quickly and repetitively so that large numbers of animals or fish can be processed.

[0005] Pneumatically powered apparatus is used for larger animals because it meets the needs set out in the previous paragraph. However, such apparatus is not suitable for use with smaller animals or fish. Smaller hand-held pneumatic devices are known-for example, pneumatically powered nail guns-but these are not suitable for use as a fish or animal stunning device because of their configurations. Such devices are nevertheless capable of delivering an adequate force.

[0006] The object of the invention is to provide a stunning device that can be used for the rapid and repetitive stunning of small animals or fish and that utilizes pneumatic power.

[0007] In a broad format, the invention provides an animal or fish stunning device comprising:

[0008] a pneumatically-powered piston assembly comprising a piston retractably extendable from an open ended cylinder included in said assembly;

[0009] a support for said piston assembly including a base member, wherein said piston assembly is positioned with respect to said base member to define a space between said base member and said cylinder open end for receiving a head of an animal or fish, and wherein said piston can extend partially into said space; and

[0010] a trigger for activating extension of said piston when said trigger is contacted by the head of said animal or fish when positioned in said space.

[0011] The operating principle of the stunning device according to the invention is that that the animal or fish is killed by a blow to the head administered by the piston of the device. The action is initiated by insertion of the animal's or fish's head into the space between the base member of the support for the piston assembly and the open end of the cylinder whereby contact with a trigger activates the piston. The trigger and cylinder are configured such that when the piston is activated, it strikes the animal or fish just behind and/or between the eyes. This impact is sufficient to kill the animal or fish due to the shock to the brain.

[0012] A design feature of the device is that when activated, the piston extends only once and then retracts. Removal of the animal or fish resets the trigger so that the device can be immediately used to stun another animal or fish.

[0013] The piston assembly of devices according to the invention is advantageously pivotally mounted to the support so that the distance between the base member and the open end of the cylinder can be adjusted to allow use with differently sized animals and fishes. The piston assembly can be either fixed in a particular position or mounted such that some degree of movement is possible. This allows for automatic adjustment of the distance between the base member and the open end of the cylinder when differently sized individuals of the same species of animal or fish are to be slaughtered.

[0014] The mounting of the piston assembly to the support is typically such that the assembly can be demounted to allow cleaning of both components. Devices advantageously include guide plates to facilitate insertion of the head of the animal or fish into the space between the base member of the support and the open end of the cylinder. Preferably, the distance between guide plates at each side of the entrance to the device is adjustable. Advantageously, the entire device can be dismantled for cleaning of all components.

[0015] The support for the piston assembly advantageously comprises a planar base member and planar side members. Alternatively, the support can be a framework of elongate members.

[0016] The pneumatic operation of the piston is typically effected by incorporating apparatus commonly known as a “nail gun” in the piston assembly of devices according to the invention. As such guns are typically capable of repetitive firing on activation, devices include a mechanism which allows only a single extension of the piston. This will be explained in greater detail below. However, it will be appreciated by one of skill in the art of the manufacture of such devices that the pneumatically-operated piston can be any suitable assembly including a purpose-built assembly.

[0017] Devices according to the invention can be used with small animals and are particularly suited for use with animals having a weight of 2 to 7 kg. With regard to fishes, devices can be conveniently used with fish having a weight of up to about 7 kg such as salmon, trout and sea bass. Devices are most particularly suited for the stunning of salmon during the commercial processing thereof.

[0018] With devices according to the invention, animals or fish to be processed can be rapidly and efficiently stunned with minimal risk of injury to the operator. Furthermore, as triggering is effected by the head of the animal or fish, both hands of the operator can be used to guide the head of the animal or fish into the device. An additional advantage of devices according to the invention is that the external appearance of the animal or fish is not affected by the killing process. This is particularly important for sale of whole fish. The quality of fish is also enhanced through more rapid and humane killing at the point of harvest.

[0019] Having broadly described the invention, stunning devices will now be exemplified with reference to the drawings briefly described hereafter.

[0020]FIG. 1 is a perspective view of a device according to the invention.

[0021]FIG. 2 is a side view of the device shown in FIG. 1 with portions of the support for the piston assembly omitted.

[0022]FIG. 3 is a side view of another device according to the invention with a side member of a support assembly omitted to expose features of the device.

[0023]FIG. 4 is a side view of the support assembly of the device shown in FIG. 3 with components omitted to expose adjustment and release mechanisms.

[0024]FIG. 5 is a detailed view of the adjustable mounting for a guide plate.

[0025] The same item number has been used for features appearing in more than one drawing.

[0026] The devices depicted in the figures are designed for the stunning of adult salmon in the commercial processing thereof. However, it will be appreciated that with appropriate reconfiguration, the device can be adapted for use with other fishes or animals.

[0027] In FIGS. 1 and 2, there is shown device 1 comprising piston assembly 2 and support assembly 3. To first deal with the support assembly, this comprises a planar base member 4 and planar side members 5 and 6 linked by a cross-piece 7. In FIG. 2, side member 6 has been omitted so that other features of the device can be seen. Support assembly 3 further includes guide plates 8 and 9 that are adjustably fixed to side members 5 and 6, respectively. Taking guide plate 9 as an example, fixing is via a shaft 10 extending from an end of the guide plate, which shaft can be locked—typically via a threaded stud—into a collar 11 on side member 6. Base member 4 has fixed thereto a chin plate 12 which aids proper positioning of the head of the fish in the device as will be explained below.

[0028] Turning to piston assembly 2, this is pivotally mounted to an axle 13 extending between side members 5 and 16 to which rails at each side of the assembly are connected. One of these rails is item 14 of FIG. 2 which is the rail furthest the viewer. The rail at the other side of the piston assembly has been omitted to again allow features of the assembly to be seen. Pivoting of piston assembly 2 is limited in movement away from base member 4 by adjusting screw 15 in cross-piece 7 which contacts a tab 16 extending from the assembly. The minimum distance between open ended cylinder 17 from which the piston of the piston assembly extends and chin plate 12 is set by an adjusting screw 18 on the piston assembly which contacts a tab 19 projecting inwardly from side member 6. Adjusting screw 18 and tab 19 are shown in phantom in FIG. 2. It will be appreciated from FIG. 2 that with adjusting screws 15 and 18 set as shown, some pivoting of piston assembly 2 is still possible. That is, the piston assembly can pivot until tab 16 contacts the end of adjusting screw 15. This allows adjustment of the distance between cylinder 17 and chin plate 12 to compensate for differently sized fish.

[0029] Cylinder 17 is essentially a sleeve mounted to a standard pneumatic gun 20, the particular gun in the example being a Max Model No. NF510 manufactured by Max Co., Ltd, Tokyo, Japan. The cylinder bore is indicated by the dashed lines in FIG. 2. The normal piston of the gun is replaced with a sealed hollow stainless steel cylinder of about 100 mm in length. The end of the piston that extends from the cylinder has a convex curvature to minimise damage to fish to be stunned which could occur with a piston having a flat extremity. The cylinder has mounted at its open end a head plate 21, with an appropriate aperture therein to allow passage of the piston, to further aid positioning of a fish in the device.

[0030] The trigger of device I comprises a contact plate 22 adjustably linked to a pivot frame 23 which has a pushrod 24 extending therefrom for contacting the activating button 25 of pneumatic gun 20. Pushrod 24 is also acted on by a pneumatic pushrod 26 that disengages pushrod 24 from button 25 during operation of the device. This will be explained below. The position of contact plate 22 relative to the head 27 of a fish positioned in the device can be set by adjusting the angle between the contact plate and pivot frame 23 via adjusting screw 28. Pivot frame 23 is biased to a pre-firing position as shown in FIG. 2 by spring 29 with the position adjustable via a stop screw 30. The movement of pushrod 24 is limited by a stop screw 31 and the pushrod is biased to the button 25 contact position shown in FIG. 2 via spring 32. The piston assembly also includes a five-way valve 33, the function of which will be described below.

[0031] Device components such as the support assembly 3 are typically fabricated from a corrosion resistant metals material. A preferred material is stainless steel. The support assembly of the exemplified device has a length of about 370 mm, a width of about 185 mm, and a height of about 205 mm. The pneumatic nail gun component 20 of the piston assembly utilizes a normal air supply of 3.0 to 5.0 bar and typically operates at 3.5 bar. The device is suitable for stunning fish such as salmon of 2 to 7 kg.

[0032] Operation of device 1 will now be described. To stun a fish, the head 27 thereof is positioned in the space between head plate 21 and chin plate 12 aided by guide plates 8 and 9. Movement of fish head 27 further into this space ultimately results in the nose 34 of the fish meeting contact plate 22 which causes pushrod 31 to depress button 25 of pneumatic gun 20. The piston then extends from cylinder 17 by up to about 30 mm thereby contacting the head of the fish. To prevent multiple firing of the gun (which would result in excessive damage to the fish), pushrod 24 is stopped by stop screw 31 so that depression of button 25 is only to an initial (single fire) position. To allow immediate retraction of the piston, pushrod 24 is disengaged from button 25 by pneumatic pushrod 26. The latter pushrod is activated by five-way valve 33 which senses a drop of pressure on firing of the gun to extend the piston with air being diverted to the pushrod. On removal of the stunned fish, contact plate 22 and pushrod 24 are returned to the positions shown in FIG. 2 under the action of springs 29, and 32, respectively.

[0033] The device is then ready for repetition of the foregoing procedure.

[0034] Device 1 is typically fixed to a horizontal surface, such as a bench top, for use. However, it will be appreciated that the device can be used in any orientation.

[0035] In a variant of the device exemplified above, the pneumatic pushrod 26 and five-way valve 33 can be replaced by a spring-extended double acting cylinder arrangement, thus avoiding the need for the five-way valve.

[0036] A variant of the device shown in FIGS. 1 and 2 is depicted in FIGS. 3 and 4. With reference to FIG. 3, there is shown device 35 comprising piston assembly 36 and support assembly 37. The support assembly 37 is essentially the same as support assembly 3 of the device described above. Differences will be discussed below.

[0037] The piston assembly 36 includes a standard pneumatic gun 38 which in this case is a Max Model No. NF352-ST/16-50 obtainable from Max Co., Ltd, Tokyo, Japan. As this gun has a shorter barrel than the gun used in the FIGS. 1 and 2 device, a sleeve 39 is mounted between gun 38 and cylinder 40, which cylinder 40 is similar to cylinder 17 of the FIGS. 1 and 2 device. In the present case, the piston within cylinder 40 is solid and is connected to the piston of gun 38 by a solid rod not shown in the figure. The piston is grooved at its upper end, which groove has an o-ring therein. The o-ring prevents slippage of the piston in between firings of the gun. These details are again not shown in the figure.

[0038] The trigger mechanism of device 35, and the operation thereof, is the same as the trigger mechanism of the FIG. 1 and 2 device. One difference in the operation of the gun, however, is that there is a supply of air to the body of gun 38 which air acts on the underside of the gun piston to aid retraction of the piston after firing. This supply of air is from a branch line 41 of the air line 42 from five-way valve 43 to the pushrod 44 that is the equivalent of pushrod 26 of the FIGS. 1 and 2 device. Consequently, after the gun is fired, there is a momentary supply of air through line 42 and hence then to the gun body via line 41 to aid cylinder retraction.

[0039] Device 35 further includes a pressure relieve valve 43a which receives air from a compressor. The device typically operates at 5.0 bar.

[0040] Device 35 also has a cover, shown in phantom as 45 in FIG. 3, secured to support assembly 37 by a spring clip on each side of the device, one of which spring clips is shown at 46. The device has two guide plates like those of the FIGS. 1 and 2 device but of the same length. One of the guide plates, 47 of FIG. 3, is hinged at its mid-point 48 with the distal half 49 biased away from the centre of the device. When the device is mounted close to a wall with guide plate 47 on the side of the device closest the wall, the distal half 49 will contact the wall thereby closing any gap between the device and the wall. This prevents a fish entering the gap between the device and the wall. The distance between the guide plates can be adjusted by the independent setting of each plate by a mechanism to be explained in detail below.

[0041] The angle of chin plate 50 of device 35 can be adjusted. The chin plate is pivotally mounted to the base 51 of support assembly 37 at 52. A spring-loaded pin at the distal end of the chin plate is received in one of the notches in a notched plate 53 on a side wall of the support assembly.

[0042] Greater detail of adjustment mechanisms is presented in FIGS. 4 and 5. In FIG. 4, there is shown the base member 51 and a side member 54 of support assembly 37. A support rail 55 for gun 38 is pivotally mounted at 56 to side member 54. The position of the gun is adjustable by virtue of adjusting screw 57.

[0043] To aid cleaning of the device, piston assembly 36 can be pivoted out of support assembly 37 once cover 45 has been removed. To allow this, a boss 58 at the end of adjusting screw 57 can be released from a clasp 59 therefor by virtue of a lever 60 acted on by an over-centre spring which normally retains the clasp about boss 58.

[0044] Adjusting screw 57 is adjacent side wall 54. The upper end of the screw has a tee-piece 61. This tee-piece cannot rotate when the adjusting screw is locked in position and cover 45 is in situ. Consequently, movement generated by operation of gun 38 does not alter the setting of rail 55 and hence the position of cylinder 40 relative to base member 51 (see FIG. 3).

[0045] When lever 60 is in the released position-which can only occur when cover 45 is removed—the lever lies across spring clip 62, the complement of spring clip 46 of FIG. 3. Consequently, the cover cannot be refitted. This prevents use of the device when adjusting screw 57 is not properly latched. Spring clips 46 and 62 can be interlinked so that blocking of only one clip prevents operation of both clips.

[0046] A mechanism for the adjustable mounting of a guide plate to side member 54 is shown at 63 of FIG. 4 and in more detail in FIG. 5, the latter being an exploded view. FIG. 5 shows a shaft 64 which projects from the end of the guide plate within the support assembly (see FIG. 3). This shaft is received in a boss 65 on a side wall of the support assembly. Shaft 64 includes a plurality of grooves 66 into one of which a spring loaded plate 67 can drop when the shaft is in boss 65. This locks shaft 64 in a particular position and thus sets the position of the attached guide plate relative to the side walls of the support assembly. Lifting plate 67 via tab 68 allows repositioning of the shaft and hence the guide plate.

[0047] The device illustrated in FIG. 3 is operated in the same manner as the FIGS. 1 and 2 device.

[0048] It will be appreciated that many changes can be made to the stunning devices and use thereof as exemplified above without departing from the broad ambit and scope of the invention.

[0049] The term “comprise”, or variants thereof such as “comprising” or “comprised”, is used herein to denote the inclusion of a stated integer or integers, unless is the context of usage an exclusive interpretation of the term is required.