Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to an apparatus for electrically stunning animals
to be slaughtered, in particular pigs, comprising two endless conveyors, said
conveyors being operable to run parallel to each other and at a synchronized
rate and being positioned to form a substantially V-shaped passage way between
the operating surfaces thereof, as well as a pair of electrodes or sets of
electrodes, said electrodes or sets of electrodes being insulated with respect
to each other and being adapted to extend into said V-shaped passage way, said
electrodes furthermore being adapted to engage the head of the animal to be
stunned and to clear said passage way, and comprising furthermore means opera-
tive to make zero in principle the speed difference between the electrodes
and the conveyors upon closure of the current circuit between said electrodes
or said sets of electrodes, respectively.
A similar apparatus has been described in our older Dutch patent appli-
cation 79.03681 published November 10, 1980, which patent application per se
constitutes a further development of the apparatus according to our Dutch patent
application 77.05519 published November 18, 1978.
In both instances, the electrodes or sets of electrodes, respectively,
are arranged in a spaced relationship to each other in the direction of convey-
ance. Consequently the animal transported by the conveyors will first be en-
gaged by the first electrode or first set of electrodes, respcctlvely, passing
over the head of the animal while onJy upon engagcmellt betweell the second elec-
trode of the second set of elcctrodes, respectively, a current wlll start
to flow, initially at slight intensity for determining whether a proper con-
tact has been made or not and upon determining a proper contact a jolt of
current of sufficient intensity to cause the stunning.
Like it has been explained already in the older Dutch patent applica-
tion 79.03681 when stunning one has to take care that no improper or insufficient
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current passage occurs because such a current passage will lead to damaging the
animal to be slaughtered. The current passage required for the stunning should
pass directly through the head of the animal at the correct potential and the
correct intensity. When such current passage is not obtained or it is insuf-
ficient, arbitrary muscular contractions will occur causing bone breakage and
internal bleedings respectively. The meat of such an animal will then be
classified in a lower quality class.
When stunning with the aid of manually operated stunning means there
are utilized stunning rods which may be made to engage the head of the animal
either in the longitudinal direction or in a direction transverse thereto.
The percentage of animals that may not be considered to be of prime quality be-
cause of internal bleedings and bone breakage, respectively, is relatively low
and amounts to only some animals per one thousand thereof. The manual stunning
presents, however, the draw back that upon increasing production the drop out
percentage increases too because the operators performing the manual stunning
will then be subjected to a greater stress.
For avoiding the situation that the animal to be stunned is only uncon-
scious and hence seems to be stunned but has not been stunned in reality it is
desired to use a higher voltage than would be safe for the operators. Most
of the above-mentioned considerations have only become apparont after Filing
the above-mentioned Dutch patent application 77.05519.
The application of the latter apparatus in practice was conducive to
a higher drop out percentage than that occurring in manual stunning. As a
consequence thereof there has been a assiduous search for finding further
improvements such as the provision of a damping device for damping the movements
of the electrodes in the proposition according to our Dutch patent application
79.03678, published November 10, 1980, the maintenance of a fixed distance
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between the electrodes according to our Dutch patent application 79.03680
published November 10, 1980 and the joint movement of the electrodes and the
animal according to the above-mentioned Dutch patent application 79.03681.
Although these improvements were conducive to a decrease of the drop out per-
centages such decrease was not sufficient.
The object of the invention accordingly is to provide an apparatus in
which the occurrence of drop out will be lower than that in manual stunning.
Surprisingly this object is now attained in that the two electrodes or
sets of electrodes, respectively, are or have been arranged side by side in the
passage way and said electrodes or sets of electrodes, respectively, are of
such a shape and have been mounted in such a manner that they are operative to
engage the sides of the head of the animal substantially at the same time.
The electrodes are thus not positioned anymore in a consecutive manner but side
by side so that the current will pass transversely through the brains of the
animal. When applying the consecutive electrode arrangement the animal could
already become disquieted upon being engaged by the first electrodes. This
situation is now prohibited. In the present arrangement the animal will be
engaged by both the electrodes substantially at the same time. Thereupon a
sensing current of low voltage will start to flow, said current registering
whether the proper resistance is presented or not. Every kind of animal pre-
sents its own specific resistance so that it is therefor possible to determine
whether the animal is e.g. a pig or not on the basis o~ this current. When a
current connection between the electrodes is established in this manner, this
being the case when the electrodes engage the head of the animal in the pro-
per way, the main current is switched in and the stunning occurs.
It is very surprising that in this way an automatic stunning may
be attained at a drop out percentage that is not only lower than that in the
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older propositions for automatic stunning but also lower than that in manual
stunning particularly in manually stunning with electrodes placed on the head
in a transverse manner. While maintaining the proper quality, that is to say
at an equally low drop out percentage, the production may now be increased
considerably.
Thus, in accordance with a broad aspect of the invention, there is
provided an apparatus for electrically stunning animals to be slaughtered,
comprising: two endless conveyors, said conveyors being operable to run paral-
lel to each other and at a synchronized rate and being positioned to form a
substantially V-shaped passageway between the operating surfaces thereof; a
pair of electrodes carried by a movable frame, said electrodes being insulated
with respect to each other and being adapted to extend into said V-shaped
passageway, said electrodes being further adapted to engage the head of the
animal to be stulmed and to clear said passageway; and means for moving said
movable frame, said means being adaptable to move said movable frame at said
synchronized rate, the two electrodes being arranged side by side in said
passageway, said electrodes being of such a shape and mounted in such a manner
that they are operative to engage the sides of the head of the animal substan-
tially at the same time.
Preferably the apparatus is constructed in such a manner that the two
electrodes COllSiSt of two plates, thc outor edgcs of which are substuntinlly
parallel to each other and run at closc proximity to the pertaining operating
surfaces of said conveyors and the edges oE which facing each other diverge from
the lower ends thereof in upward direction up to about half the height of said
plates whereupon by means of a curvature said latter edges merge into a conver-
ging portion. When applying this shape there will be excluded the danger that
the animal will put its head into the gap between one electrode and one con-
veyor. The animal will seek the
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space between the two electrodes whereby the snout of the animal will seek
more or less unintentionally the correct position with respect to the
electrodes so thzt these electrodes will pass across the sides of the snout
and head. The current will then be switched in at the correct moment while
using optionally, apart from the above mentioned sensing current~ an
adjustable time relay so that the current will pass with certainty
transversely through the brains at the correct position. When the stunning
jolt of current is switched in a movement is imparted to the electrodes e.g.
in the way like described in the Dutch patent application 79.03681 so that
the proper contact will remain assured. The difference in velocity between
the conveyors and the frame will then be reduced substantially to zero.
Preferably, when viewed in the direction of conveyance, the
electrodes have been mounted or shaped in such a V-shaped or arcuate manner,
respectively, that the parts of said two electrodes or sets of electrodes
respectively at closest distance from each other extend also farthest to the
front in the direction of conveyance. It is preferred that this V-shape or
arcuate shape is most pronounced and half the height of the electrodes. This
shape is the most favourable for catching the head of the animal in the most
appropriate way.
The invention will now be elucidated in detail with refcrellce t~
the drawings.
Figure 1 shows a side elevation, partially in cross section, along
the line I-I in Figure 2 of the apparatus according to the invention.
Pigure 2 shows a cross section along the line II-II in Figure 1
With reference to Figure 1 there have been shown two conveyors 1 and
2, said conveyors being positioned to form a substantially V-shaped passage
way between which conveyors the animals may be transported in a way known per
se,
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Gn the top of the frame 3 of the apparatus, said frame only being
indicated schematically in Figure 2 there is a frame 4 said latter frame
being fastened to the former one. Said frame 4 comprises lower and upper
channel members, the flanges of which facing each other are provided with
V-shaped rail surfaces 5 and 6 for the runners 7 of a
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frame 8.
In said frame 8 two electrodes 9 and 10 are rotatably
mounted on a shaft 11 which electrodes are hingedly coupled
to a damped spring 13, by means of a rod 12 said spring being hingedly
fastened in the frame 8 at 14. In a way not shown but known per se
the electrodes 9 and 10 are insulated with respect to each other on
the shaft 11 as well as with respect to the frame 8. In a way not
shown the electrodes have been further connected to current conduc-
tors.
On top of the frame there is a support 15 in which there
has been fastened a hydraulic cylinder 16 inc].uding a motor driven
pump 17 coupled thereto. The piston rod ].8 of the cylinder 16
has been coupled by means of a lever 19 to the frame 4 and to the
fra~e 8 at 20 and at 21, respectively. A movement of the piston rod
to the right handside will be conducive to a movement of the frame
8 together with the electrodes in the direction of conveyance.
The el.ectrodes 9 and 10 possess outer side edges 22, 23
running parallel to the operating surfacesof the conveyorsl and 2
and at close proximi.ty thereof.
The inner edges facing each other possess diverging lower
portions 24 and 25 merging by means of a curvature 26, 27 into
converging portions 28, 29, the latter merging fi.nally into parallel
edge portions 30
In hori.zontal cross section each one of the electrodes
is curved, tlle strongest curvature being present at the level oF the
portion 26 or 27 respectively. This curvature is such that, when
viewed in the directlon oF conveyance, the etlges 26 and 27 , respec-
tively, will be present in Front oF the edges 22, 23 and will pre-
ferably form part of an arc. In the lower portion and in the upper
portion, that is to say the portions having diverging eclges 24, 25
and converging edges 28, 29, respectively, this curvature may be
less pronounced. It is conceivable to use an embodiment in which,
when viewed From below, the lower portions of the electrodes
constitute flat planes positioned to Form together a V-shaped
border line , said planes either maintaining said V-shaped
though at a change of the angle or merging into a curvature.
