Stunning device for animals for slaughter

Abstract: A device for stunning animals for slaughter, such as pigs, sheep and the like. Prior to slaughter of the animal a stunning treatment takes place, wherein a current pulse is carried through the head of the animal. Use is made for this purpose of two electrodes which are pressed from two opposite sides against the head of the animal. After the electrodes have been thus pressed on, a current is passed through the electrodes whereby the animal is stunned. In this respect the device according to the invention has the special feature that the electrodes have in substantially vertical direction an independent first translation degree of freedom.

Description: The invention relates to a device for stunning animals for slaughter, such as pigs and sheep, by means of a current pulse through the head, comprising two electrodes for pressing with a desired pressure from either side against the head of an animal, which electrodes are carried by a frame in a way such that they have in substantially vertical direction an independent first translation degree of freedom, allowing corresponding movements of the electrodes during said current pulse. Such a device is known from e.g. BE-A-902 574. The structure according to this prior art reference allows for a vertical movement of the electrodes. The device according to the invention is characterised in that the electrodes have in horizontal direction an independent second translation degree of freedom, the directions of which first and second degrees of freedom define a plane lying in lengthwise direction of an animal for treating, allowing corresponding movements of the electrodes during said current pulse; and in that the device comprises a restrainer for carrying an animal for slaughter. It is noted that the restrainer, that can e.g. can be embodied as a conveyor, immobilizes the animal, so that the animal lies sedately on the restrainer. The current pulse flowing through the head of an animal via the electrodes has the effect of causing an abrupt upward movement of the head of the animal. The two translation degrees of freedom of the electrodes compensate for this movement, which, contrary to the mentioned prior art reference, can in no way be compensated for by the mobility of the body of the animal. The structure according to the invention ensures that the electrodes are held with complete reliablity in the desired pressed-on position during the whole time during which the current flow through the head takes place. It is noted that a stunning device is known from NL-A-7904935 wherein the electrodes are suspended for swinging. Because they can swing in a vertical plane the electrodes have two coupled degrees of freedom, one horizontal and one vertical. In the freely suspended situation the horizontal degree of freedom dominates, while the vertical degree of freedom is dependent on the horizontal degree of freedom and corresponds to a second order effect. This construction according to the prior art is therefore not capable of following the actual movement of the head of an animal during passage of the current pulse, whereby the desired press-on reliability of the electrodes cannot be guaranteed. The structure according to the above-described basic principal of the invention allows the electrode to be movable in a substantially vertical plane. It is noted that WO-A-93/16599 discloses an apparatus for electrically stunning animals to be slaughtered. Use is made of a carrier bearing at leat one electrode. This electrode configuration is by means of control means movable in a swiveling fashion. Therefore, these electrodes have no independent first and second translation degrees of freedom in substantially vertical and horizontal directions, respectively. It can occur under given conditions that the upward directed movement of the head also has a lateral component. In order to also ensure in such a case that press-on of the electrodes is maintained, the electrodes can advantageously be movable independently of each other. It has been found that the said involuntary movement of the head during passage of the current pulse takes place substantially round a pivot centre line situated in a region in the back zone of the animal. It can be assumed that this imaginary pivot centre line lies at roughly the same position for animals of comparable length. This offers, for the best possible following of the movement of the head, the possibility that the electrodes are movable round a centre line substantially coinciding with the pivot centre line around which the head of an animal for stunning moves as a result of passage of the current pulse. Alternatively the electrodes can be disposed for swivelling. Always a condition here of course is that the electrodes can be pressed with a desired force against the head of the animal prior to passage of the current pulse. The electrodes can for instance be carried by coil springs. In order to enable, as stated above, a lateral motion of the electrodes a particular embodiment can have the special feature that the electrodes have a third translation degree of freedom. This degree of freedom does not have to be independent. In the case of a swivelling movement of the electrodes it must preferably be prevented that sliding of the electrodes occurs relative to the contact surface with the head. For this purpose the device can have the feature that the electrodes are rotatable round a centre line lying in a horizontal plane and substantially transversely of the lengthwise direction of an animal for stunning, and thus have a rotation degree of freedom. The electrodes can further be carried by arms which can be swivelled round the said pivot centre line, in which case the electrodes do not have to be pivotable relative to these arms. The desired rotation can also be achieved by coupling the electrodes to coil springs. The invention will now be elucidated with reference to the annexed drawing, wherein: figure 1 shows a schematic front view of a device according to the invention in a first embodiment; and figure 2 shows a partly broken away perspective view of a second embodiment. Reference is first made to figure 1. Two side guide members 1, 2 restrict the freedom of the head of the animal, as described in the cited Netherlands patent application 92 00104. Use is made for this purpose of a cylinder 3 which, under the influence of a control system (not shown), can vary in length counter to the spring force of two springs 4, 5 which are connected to a schematically designated frame 6. The ends of cylinder 3 are connected respectively to a guide 7 and 8, which guides can be guided over a guide rod 9 connected to the frame. The side guide members 1, 2 are connected respectively to the guides 7, 8. It will be apparent that cylinder 3 can be of the single-action type, presses the side guide members 1, 2 toward each other in its energized situation and that the springs 4, 5 serve for re-setting to the rest position. The guide rod 9 further bears a guiding 10 guided slidably thereover. This guiding 10 is coupled via springs 11, 12 to the guide rod 9. Because the meeting point 13 of the springs 11, 12 is connected in the manner shown in the figure to the guide rod 9, they thus define a rest position of the guiding in relation to the guide rod 9. The guiding 10 thus reciprocally movable counter to the force of the springs 11, 12 supports a frame 14 which via hinges 15, 16 bears arms 19, 20 carrying electrodes 17, 18. These arms 19, 20 can be swivelled by means of a cylinder 21 which can likewise be controlled by way of means (not drawn) between a position in which the electrodes 17, 18 press with a desired force against the head 22 of an animal for stunning and a second position in which the electrodes are free. The frame 14 is supported for up and downward movement by the guiding 10 via a guide 23 slidable over a guide rod 24 which is connected to guiding 10. Guide 23 is coupled via a spring 25 to the horizontal guiding 10 and supports via a spring 26 the frame 14. If desired, spring 26 can be replaced by a rigid coupling. In the above described manner the desired horizontal and vertical movement of the electrodes 17, 18 is guaranteed. Figure 2 shows a pig 27 which is carried by a so-called restrainer 28. A pig 27 for treating lies sedately on this restrainer embodied as a conveyor belt and is transported lying thereon at a determined speed. When the head 22 of the pig has reached the electrodes 17, 18 pressing of these electrodes in tipped form against head 22 takes place by energizing the cylinder 21. By way of means such as a hydraulic cylinder (not shown) a carriage 29, which carries the electrodes 17, 18 by means of a frame 30, is driven at the same speed as restrainer 28. The electrodes 17, 18 can thus follow the pig 27 during the stunning treatment. It will be apparent that the time for which the carriage 29 must move along with the pig corresponds with the time for which the current pulse must be passed through the electrodes 17, 18. Carriage 29 is guided rollably in rails 31, 32 extending parallel to restrainer 28. The frame 30 is pivotally supported by a second frame 32 which is in turn pivotally supported by carriage 29. The frame 32 can swivel relative to the carriage under the influence of a cylinder 33 which is coupled on one side to the frame 32 and on the other side to a protrusion 34 on carriage 29. The swivel frame 30 has an upward protruding part with horizontal arm 35, which arm is connected via a second cylinder 36 to the carriage 29. It is noted for the sake of completeness that control of cylinders 3, 21, 33, 36 and the drive cylinder for the reciprocating movement of carriage 29 are not drawn. Also dispensed with is drawing of the electrical unit which provides the passage of a current pulse via the electrodes 17, 18. As remarked above, the carriage 29 is moved along with the pig 27 prior to passage of the current pulse through electrodes 17, 18. The cylinder 36 is placed in a fixed position while cylinder 33 is controlled such that it can operate as a spring. As a result of the construction shown the electrodes 17, 18 are movable in a substantially vertical plane round a pivot centre line 37. This is the centre line around which the head 22 of the animal will move owing to contraction of the neck muscles during passage of the current pulse. This construction ensures that the electrodes 17, 18 remain pressed in the correct manner against the head and ensures the quality of the stunning. After the stunning operation has been performed the cylinder 33 is placed in a fixed position and cylinder 36 is energized to pull toward it the arm 35, whereby the lower part of the frame 30 with the electrodes 17, 18 is folded upward. In this situation the device is ready for stunning of the following pig and the carriage 29 can move back to its starting position. Connected to the first frame 30 are curved plates 38, 39 which serve during delivery of an animal 27 to correctly position the head 22 in relation to the electrodes 17, 18. As shown in figure 2, the aligning plates 38, 39 have for this purpose a form such that they together form a generally funnel-shaped outer surface, whereby a correct positioning of the head 22 facing to the front is always ensured. Attention is drawn to the fact that the aligning plates 38, 39 can be the electrodes themselves, in which case the electrodes 17, 18 and the associated support and control construction could be omitted. It is however pointed out in this respect that, given present insights, it is recommended to choose the shape of the electrodes 17, 18 such that at least the outer portion of the skin of the head 22 is slightly penetrated to ensure an optimal passage of current. To this end the electrodes can have tips, have a sharp edge or have a number of sharp portions disposed for instance in a ring.

Claims: Device for stunning animals (27) for slaughter, such as pigs and sheep, by means of a current pulse through the head (22), comprising two electrodes (17, 18) for pressing with a desired pressure from either side against the head (22) of an animal (27), which electrodes (17, 18) are carried by a frame (6) in a way such that they have in substantially vertical direction an independent first translation degree of freedom, allowing corresponding movements of the electrodes (17, 18) during said current pulse, characterized in that the electrodes (17, 18) have in horizontal direction an independent second translation degree of freedom, the directions of which first and second degrees of freedom define a plane lying in lengthwise direction of the animal (27) for treating, allowing corresponding movements of the electrodes (17, 18) during said current pulse; and in that the device comprises a restrainer (28) for carrying an animal (27) for slaughter. Device as claimed in claim 1, characterized in that the electrodes (17, 18) are movable independently of each other. Device as claimed in claim 1, characterized in that the electrodes (17, 18) are movable round a centre line substantially coinciding with the pivot centre line around which the head (22) of an animal (27) for stunning moves as a result of passage of the current pulse, allowing corresponding movements of the electrodes (17, 18) during said current pulse. Device as claimed in claim 1, characterized in that the electrodes (17, 18) are disposed for swivelling, allowing corresponding movements of the electrodes (17, 18) during said current pulse. Device as claimed in claim 1, characterized in that the electrodes (17, 18) have a third translation degree of freedom, allowing corresponding movements of the electrodes (17, 18) during said current pulse. Device as claimed in claim 1, characterized in that the electrodes (17, 18) are rotatable round a centre line lying in a horizontal plane and substantially transversely of the lengthwise direction of an animal (27) for stunning, and thus have a rotation degree of freedom, allowing corresponding movements of the electrodes (17, 18) during said current pulse.

Inventors: PARDIJS HENDRIK JAN, TE DORSTHORST WILHELMUS ANTONI, PARDIJS, HENDRIK JAN, TE DORSTHORST, WILHELMUS ANTONIUS BERNARDUS
Applicants: STORK RMS BV, STORK R.M.S. B.V.
Application year: 1993
Main classification: A22B3
IPC codes: A22B3