The invention relates to a fish stunning apparatus and a method for using said fish stunning apparatus.

Background of the invention.

The fish farming industry has grown into a large industry, and Norway sold more than 1 ,45 million tons fish and shellfish in 2019, having av value of about 71.7 billion Norwegian kroner. The producers are mainly professional firms, and the industry is subjected to many regulations, both to ensure food safety, but also to ensure fish welfare.

The handling of the fish generally, but particularly shortly before slaughtering, is important to achieve the best food quality, as stress reduces the quality of the fish meat. Further, slaughtering fish is subjected to strict regulations due to fish welfare. Before cutting a major blood vessel of the fish and draining the blood from the fish to ensure its dead, it must be unconscious. This is to avoid unnecessary suffering if the fish where conscious and killed alone by cutting a major blood vessel.

Several attempts has been generated for stunning the fish, for instance as described in WO 2005089558 or WO 2008148455. Both these devices uses a stunning apparatus hitting the head of the fish as it passes through the device.

However, both the known stunning devices have quite a limited capability for handling of fish of different size. When handling fish having a size out of the given range, the fish may not be in the correct position when hit by the stunning apparatus, and the hit may not be on the optimal position of the fish. The stunning may thus be insufficient, or too powerful, whereby the fish is not only stunned but also crushed, and pieces offish and fish blood may prevent the device from operating optimal.

The main object of the present invention is to develop a stunning apparatus suitable for handling fish of different size at an acceptable rate, and further that the apparatus should stun each fish precisely. Another object is that the fish, once leaving the apparatus should be prepared for further processing. All regulations and considerations regarding fish welfare and food processing should of course be met.

The invention

The invention relates to a fish stunning apparatus a method for using said fish stunning apparatus as stated in the independent claims. Further advantageous features are stated in the dependent claims.

The fish stunning apparatus comprises: at least one fish stunning device and at least one fish guide.

The fish stunning device incudes; a striker. The striker comprises a cylinder, and a piston with a connected piston rod. The piston is arranged in the cylinder to move the piston rod between a retracted position and an extended position.

The fish stunning device further includes a trigger mechanism connected to the striker and arranged to trigger the striker to extend the piston rod to the extended position.

The fish guide has an entrance and an exit. The fish guide further comprises an exit ramp, the exit ramp is an extension of a U-shaped lower part of the fish guide. The exit ramp is stretching from a bend in the U-shaped lower part to the exit. The exit ramp has an angle relative to the rest of the U-shaped lower part of between 25 and 45 degrees.

The fish stunning device is pivotally arranged relative to the fish guide between an open position not limiting the fish guide and a closed position whereby an end of the piston rod in its extended position is at a predetermined distance from a bottom of the fish guide. Further a fish in the fish guide may activate the trigger mechanism when the fish stunning device is in the closed position.

The trigger mechanism may further include an activator, meaning a trigger or other device arranged to initiate the trigger mechanism based on some sort of external input, in this case the presence of a fish in a particular position. Examples of such activators is mechanical activators that is activated by a fish touching or pressing on the activator, or sensors such as photocells, a laser or similar.

By the expression trigger mechanism, it is herein meant a mechanism for initiating a further action in this case the extension of the piston rod. The trigger mechanism can preferably be an electrical mechanism or a mechanical mechanism, but hydraulic or pneumatic mechanisms may also be used.

The fish guide can be a sloped channel where a fish will slide from the entrance towards the exit. The fish guide can have a width that is smaller than the expected length of the fish to prevent the fish from sliding sideways. The cross-section of the fish guide is preferably U-shaped which will keep the fish in and upright position. At the bottom of the U-shaped fish guide, being the bottom of the U-shape, a number of holes or a slit may preferably be arranged to drain of any water in the fish guide.

By the word "bend" it is herein meant a position wherein the fish guide changes direction, such as a curve, kink, break, elbow or the similar.

The fish guide may have sides which are designed to keep fish of a wide size range upright. This is particularly enabled by designing the sides in two parts, a lower part being the sides of the U-shape and an upper part arranged at a distance above the lower part. The upper part is spring biased towards the center of the fish guide, which makes each side act as a blade spring and act towards the surface of the fish, when larger fish pass through.

The fish stunning device can further be equipped with guide/stop plates arranged in the fish guide when the fish stunning device is in the closed position, and will help positioning and holding the fish in place for the stroke.

The guide/stop plates are arranged along the sides of the fish guide when the fish stunning device are in the closed position. In embodiments where the fish guide comprises both upper side parts as described above, and guide/stop plates, the upper side parts of the fish guide are preferably not extending along the exit ramp of the fish guide, and the guide/stop plates may protrude beyond the upper side parts extending the sides of the fish guide towards the exit. The guide/stop plates may be arranged on the outer side of the upper side parts.

The distance between the guide/stop plates may be reduced towards the exit, creating a more narrow fish guide. This will contribute to hold the fish upright, and also to stop the fish in the correct position for being stunned. The activator mentioned above can be a part of such guide/stop plates and formed to stop the fish when the fish stunning device is in the closed position, in addition to activate the trigger mechanism. The activator may for instance be arranged between the ends of the stop/guide plates, and thus the stop/guide plates and the activator creates a blockage in the fish guide, once the stunning apparatus are in closed position.

The fish preferably enters the fish guide swimming head first from a water filled reservoir, and will thus enter the fish guide head first and belly down. Water can be strained from the fish inside the fish guide. As the fish guide is arranged to keep the fish upright, the fish will enter the stunning device in a known orientation.

The cylinder and the piston can preferably be pneumatic, but hydraulic or electric mechanisms may also be used.

When the fish stunning device is in its open position it is not limiting the fish guide. By not limiting the fish guide it is meant that fish can pass through the fish guide without being effected by the fish stunning device.

The fish stunning device including the striker and trigger mechanism is pivotably arranged so that it can pivot relative to the fish guide. The fish stunning device can be arranged in such a way by equipping it with an arm that is connected to a frame of the fish guide, for instance via a hinge. An actuator such as a piston-cylinder assembly can be arranged to pivot the fish stunning device around a pivoting axis of the hinge between the open and the closed position. When the fish stunning device is in closed position, an end of the piston rod in its extended position is at a predetermined distance from a bottom of the fish guide. When there is a fish in the fish guide, the piston rod will strike the head of the fish, and the fish becomes stunned. The distance from the bottom of the fish guide, to the end of the piston rod when the piston rod is in its extended position, will depend on the expected size of the fish. The expected size of the fish is therefore decisive for the distance between the fish guide and the stunning device in closed position, as the end of the piston rod should be sufficiently close to the bottom of fish guide to hit the head of the fish with sufficient strength. If the distance is too large, the fish will not be sufficiently stunned, and if the distance is too narrow, the piston rod will crush the head of the fish. The distance between the stunning device and the fish guide may thus be adjustable.

Further, when the stunning device is in closed position, parts of the stunning device, such as an activator and/or guide/stop plates may prevent the fish in the fish guide from sliding through the fish stunning apparatus, and hold the fish in correct position for stunning. The positions of these parts, and their distance from the bottom of the fish guide when the stunning device is in closed position, will depend on the expected size of the fish, as described above for the position of the end of the piston rod.

Further a fish in the fish guide activates the trigger mechanism when the fish stunning device is in the closed position.

A camera can be installed above a table or conveyor placed after the stunner. The signal from the camera may be transferred to a screen or a computer whereby fish coming from the stunner can be detected and traced. A fish that is not properly stunned can therefore be detected. If the rate of fish not properly stunned increase over an acceptable threshold limit, then the entrance to the fish guide can be closed, and an alarm initiated. The computer may be including analysis programs at least including convolutional neural networks, A sensor or camera may also be arranged in the fish guide before the stunning device. The sensor and/or camera may be associated with a control system, and arranged to control if the fish sliding in the fish guide has the desired orientation (head first and belly down). Based on the outcome of said control, the control system is arranged to inhibit the trigger mechanism and pivot the fish stunning device to the open position if the fish does not have the desired orientation.

The fish stunning apparatus has several advantages compared to the existing stunning apparatuses. One advantage is that since the fish stunning device is pivotable relative to the fish guide, jammed fish can easily be removed. This is because access to the whole fish guide is possible when the fish stunning device is pivoted into its open position. Maintenance of the fish stunning device is also easier since there will be room to access the fish stunning device from the side facing the fish guide. The same goes for cleaning, inspections and making adjustments.

Testing has shown that the front of the fish, including a potentially open mouth with sharp teeth, has a tendency to stick to the activator or trigger mechanism after the stunning cycle, in stunners according to prior art. Another benefit of the present invention, pivoting the assembly of trigger and striker upwards, is that this will release the fish from the trigger mechanism, so the fish slides out easily after stunning.

The fish guide further comprises an exit ramp. The exit ramp is an extension of the U-shaped lower part of the fish guide, and positioned opposite the end of the piston rod, when the stunning device is in its closed position. The exit ramp is stretching from a bend in the U-shaped lower part to the exit. The exit ramp has an angle relative to the rest of the U-shaped lower part of between 25 and 45 degrees.

The advantage of the exit ramp is that a fish, which is thickest around the middle, also will be supported at the front (the head region) from below when it is the position where it is to be stunned by the striker. Another advantage of pivoting the stunning device, being an assembly of trigger and striker, is that it allows for an optimal shape of the exit ramp to guide and support the head of the fish during stunning, while allowing the height of the opening between the exit ramp and the trigger assembly in the open position to be higher, than the height between the fish guide and the striker and trigger assembly, upstream of the bend between the lower part of the fish guide and the exit ramp. This allows for applicability for a wide range of fish species and with a wide range of sizes within each species.

The striker can further be built up as follows. The cylinder can comprise a first cylinder chamber between the piston and a top of the cylinder and a second cylinder chamber between the piston and a bottom of the cylinder.

The piston rod is connected to the piston and extends out of the bottom of the cylinder. The piston rod has a first longitudinal part extending from the piston and a second longitudinal part extending from the first part and to the end of the piston rod. The first part has a larger cross section or diameter than the second part of the piston rod.

The striker can further comprise a piston rod sleeve extending from the bottom of the cylinder and towards the end of the piston rod. The piston rod sleeve can comprise a gasket sealing around the second part of the piston rod, and a port penetrating the piston rod sleeve between the gasket and the bottom of the cylinder. The port can be in fluid communication with the second cylinder chamber.

The first part of the piston rod is arranged to reduce the cross-sectional area where air can flow from the second cylinder chamber to the port when the first part of the piston rod enters the piston rod sleeve while extending the piston rod. The speed of the piston rod is, due to this, reduced towards the end of the extension. The first part of the piston rod has a length equal to or less than half the length of the travel of the piston rod from the extended to the retracted position. The striker described above has the advantage that an air-cushioning effect occurs as the piston approaches the bottom of the cylinder.

This air-cushioning effect reduces noise and vibration from the machine, in comparison with known machines.. In addition, it is a good protection against impact occurring if the striker is triggered when there is no fish inside the machine to receive the stroke.

The machine has a higher success rate of stunning fish correctly on a wide range of fish sizes, than other known machines. The reason for this, is likely that the striker can deliver a higher kinetic energy, and the air cushioning absorbs this kinetic energy over a longer length in the end of the stroke. A fish with a soft head or a head with a low inertia, will therefore receive a comparably smaller portion of the total kinetic energy delivered by the striker, to that of a fish with a hard head or a head with high inertia. The striker pressure can therefore be adjusted to stun big fish with less risk of damaging small fish.

A yieldable plate can be arranged between the piston rod and the fish. The yieldable plate is arranged so that the piston rod hits the yieldable plate in its extended position. Thereby the yieldable plate delivers a stroke to the head of the fish. The yieldable plate may be a part of the stunning device, and pivoted together with the piston rod from open to closed position.

The yieldable plate can be arranged in a position and orientation so that the end of the piston rod hits the yieldable plate on its travel from the retracted position to the extended position. Since the plate is yieldable it will give in and move together with the piston rod to deliver a stroke to the head of the fish. The plate can be yieldable by being flexible in itself or by being flexibly supported in its position.

The advantage of the yieldable plate is that the stroke to the fish's head is distributed out over a larger area so that there is less external visible damage to the fish. The yieldable plate will also assist in keeping the fish in place for the stroke and reducing wiggling room for the fish.

The fish stunning apparatus can comprise a closing device in the fish guide, arranged to shift between an open position wherein a single fish can pass into the fish guide and a closed position.

The advantage of this is that if there is more than one fish that is to be stunned and the more than one fish attempts to enter the fish guide simultaneous the closing device can help avoiding jamming of fish in the fish guide.

The fish stunning apparatus may comprise a device to cut a major blood vessel of the fish. The device can be arranged to be activated after the striker is activated.

The device to cut a major blood vessel of the fish can be arranged to extend into the fish guide through a slit in sides or a bottom of the fish guide. The device can be a knife that extends in through said slit to cut a major blood vessel and retracts after doing so.

A major blood vessel is preferably a major blood vessel in the throat area of the fish.

The invention also relates to a method for stunning a fish by using the fish stunning apparatus. The method comprises the following steps: a) pivoting the fish stunning device to the closed position b) allowing a fish to enter the entrance of the fish guide, c) sliding the fish along the fish guide, d) guiding the fish into a stunning position, so that the fish activates the trigger mechanism, e) striking the head of the fish by extending the piston rod so that it transfers a stroke to the head of the fish, and f) pivoting the fish stunning device from the closed position to the open position so that the fish exits the fish guide. Step a) and b) may also be in reverse order, depending on the selected timing of the cycle after the first fish has passed.

The stunning apparatus may comprise an activator, whereby a front part of the fish in a stunning position may touch the activator and thereby activate the trigger mechanism.

Fish can enter the fish guide for instance by swimming from a water filled volume over an overflow of water into the fish guide, where the water is s filtered/drained off.

The fish guide can be sloping so that the fish can slide by gravity from the entrance towards the exit.

Fish exiting the fish guide can enter a subsequent process, possible via a conveyor or another fish guiding device.

The order of the steps is not fixed to the order described above, and several step may be performed simultaneously.

The method can further comprise the step of cutting a major blood vessel of the fish after the fish is stunned. The cutting of a major blood vessel can happen in the same location as the fish is stunned.

A further step can be included where a sensor or camera and an associated control system are arranged in the fish guide, before the stunning device, and controls if the fish sliding in the fish guide has the desired orientation (head first and belly down). Based on the outcome of said control, the control system inhibits the trigger mechanism and pivots the fish stunning device to the open position if the fish does not have the desired orientation so that the fish can exit the stunning apparatus. If the fish have the correct orientation, the control system will not inhibit the trigger mechanism, and the fish will be stunned. The advantage of such a step is that one can avoid fish with the wrong orientation being injured instead of stunned.

In the description relative terms such as front, top, center, bottom, side, lower, upper, downward, upward, outward, sideward, vertical, and horizontal etc. are all related to a stunning apparatus as described above in a installed position i.e. when mounted and ready for use.

The particular features, structures or characteristics described throughout the specification may be combined in any suitable manner in one or more embodiments.

The invention will in the following be described with an example given to illustrate the invention, and should not be used to interpret the invention, as it is defined in the enclosed claims, restrictive.

Description of preferred embodiments of the invention

The invention will in the following be described with the help of the enclosed Figures, showing a preferred embodiment of a fish stunning apparatus. The different parts of the figures are not necessarily to scale in relation to each other, as the figure is merely for illustrating the invention.

The invention will in the following be described with reference to the enclosed Figures, where

Fig. 1 shows a fish stunning apparatus comprising four fish stunning devices and four fish guides.

Fig. 2 shows a section of the fish stunning apparatus in detail having one of the fish stunning devices pivoted into the closed position relative to the fish guide.

Fig. 3a shows a fish stunning device pivoted into the closed position.

Fig. 3b shows a fish stunning device pivoted into the open position.

Fig. 4 shows the striker in longitudinal cross section. Fig. 5 shows the striker in the same position as in Fig. 4, in perspective, partly in cross section. Fig. 6 shows the fish stunning device seen from the fish guide.

Reference numbers _

1 Fish stunning apparatus _

10 Fish stunning device _

11 Striker _

12 Cylinder _

13 First cylinder chamber _

15 Top of the cylinder _

16 Bottom of the cylinder _

19 Piston _

20 Piston rod _

21 Hinge _

22 Actuator _

23 Guide/stop plate (on the fish stunning device) _

24 First longitudinal part of piston rod _

25 Second longitudinal part of piston rod _

26 End of piston rod _

27 Piston rod sleeve _

28 Port _

29 Gasket _

30 Trigger mechanism _

31 Activator _

40 Fish guide _

41 Entrance _

42 Exit _

43 Closing device _

44 Water drain _

45 U-shaped lower part of fish guide _

46 Side offish guide _

47 Slit _

48 Exit ramp _

49 Bend (in U-shaped lower part of fish guide / starting point of exit ramp)

50 Height adjustment handle

An embodiment of the invention will now be described with reference to the figures.

Fig. 1 shows a fish stunning apparatus 1 comprising four fish stunning devices 10 and four fish guides 40, arranged in parallel on a common frame. Fish will enter the fish guide 40 through the entrances 41 and slide by gravity down the fish guides 40. Water will also flow into the entrance 41 and be separated from the fish through openings on the low side/bottom of the fish guide 40. Water exits the fish stunning apparatus 1 through a water drain 44. A closing device 43 is arranged near the entrance of each fish guide 40 to make sure only one fish at the time is sliding further down the fish guide 40 towards the exit 42.

The stunning devices 10 is arranged so that it can strike a fish in a stunning position between the exit 42 and the closing device 43. Each stunning device 10 is connected to the fish guide 40 via the hinge 21 and is pivoted between an open position and a closed position by the actuator 22. Fish sliding down the fish guide 40 will be stopped by the fish stunning device 10 when the fish stunning device 10 is in the closed position.

The closed and the open position of the fish stunning device 10 is defined as follows: Open position - the fish stunning device 10 is not limiting flow of fish through the fish guide 40. Closed position - the piston rod 20 is at a predefined position from the bottom of the fish guide 40 when extended. Furthermore, the fish stunning device 10 is also preventing fish from passing through the fish guide when the fish stunning device 10 is in the closed position.

The height between the stunner device and the fish guide can be simultaneously adjusted for all devices assembled in parallel on the common frame, by adjusting the height adjustment handle 50. In one embodiment, it is possible to install an actuator to adjust this mechanism and to use a control system for instance connected to a camera system that traces the fish after it has left the stunner, to find and adjust to the optimum height adjustment during operation. Such a control system may also be adjusted according to the expected size of the fish.

Fig. 2 shows the fish stunning device 10 from the side. The stunning device comprises a striker 11 and a trigger mechanism 30 with an activator 31 which in this embodiment is shown as a plate arranged at the end of the fish guide 40. The stunning device further comprises guide/stop plates 23 which will move between the closed and open position when the stunning device pivots. When the fish stunning device 10 is in the closed position the guide/stop plates 23 and trigger 30 will be arranged to create a blockage in the fish guide stopping the fish and holding it upright while it is being stunned.

The fish guide 40 is U-shaped having a bottom and walls 45, 46. A slit 47 is shown in Fig. 2 between a lower U-shaped part 45 of the fish guide 40 and upper sides 46 of the fish guide. The upper sides 46 are spring biased towards the center of the fish guide, and the slits 47 lets the side 46 bend so that it is able to keep fish of a wide size range upright.

Further the fish guide comprises an exit ramp 48, being an extension of the U- shaped lower part of the fish guide. The exit ramp 48 is stretching from a bend, shown as a kink 49, in the U-shaped lower part, and has an angle x relative to the rest of the U-shaped lower part between 24 and 45 degrees, shown as 40 degrees. The exit ramp 48 which will support the fish from below while the fish is stunned.

Fig. 3a and 3b shows the fish stunning device 10 separated from the fish guide 40. In Fig. 3a the fish stunning device 10 is pivoted into its closed position, and the actuator 22 is shown in retracted position. In Fig. 3b the fish stunning device 10 is in its open position, tilted up to allowing a fish to pass, and the actuator 22 is shown in its extended position. As shown in Fig 3b, the guide/stop 23 plates will be pivoted upwards when the stunning device is in open position.

Fig. 4 shows the striker 11 in section. The striker comprises a cylinder 12 having a top 15 and a bottom 16, and a piston 19 with a connected piston rod 20. The cylinder comprises a first cylinder chamber 13 between the piston 12 and the top 15 of the cylinder, and a second chamber (not shown) between the piston 19 and the bottom 16 of the cylinder. The piston rod 20 has a first longitudinal part 24 extending from the piston 12 and a second longitudinal part 25 extending from the first part and to the end 26 of the piston rod. The striker further comprises a piston rod sleeve 27 extending from the bottom 16 of the cylinder, arranged around the second part 25 of piston rod. The piston rod sleeve 27 comprises a gasket sealing 29 around the second part of the piston rod and a port 28 penetrating the piston rod sleeve 27 between the gasket 29 and the bottom 16 of the cylinder. The port is in fluid communication with the second cylinder chamber.

In Fig. 4 the striker is shown in the lower most position towards the bottom 16 of the cylinder 12 and consequently the piston rod 20 is in the extended position. Due to the position of the piston 19 only the first cylinder chamber 13 is visible.

The cylinder piston assembly 12, 19 is a pneumatic system. Pressurized air is accumulated in a compartment (not shown) and rapidly released into the first cylinder chamber 13 to extend the piston rod 20 with sufficient force to stun a fish. The piston 19 is returned to retract the piston rod 20 by letting pressurized air into a second cylinder chamber (not shown) below the piston 19. The air is entering the second cylinder chamber through the port 28 via a piston rod sleeve 27 above a gasket 29.

The sequence of extending and retracting the piston rod 20 is initiated by a fish sliding down the fish guide 40 pushing on the activator 31 while the fish stunning device 10 is in the closed position. This activates the trigger mechanism 30 connected to the striker 11. After or while the piston rod 20 is retracting, the fish stunning device 10 is pivoted into its open position so that the stunned fish can exit the fish guide 40.

The striker 11 has a cushioning mechanism to avoid too hard stroked against small fishes. The cushioning mechanism reduces the force and speed of the piston rod 20 towards the end of the stroke (the extended position). The cushioning effect is achieved by reducing the cross-sectional area from which air can evacuate from inside of the cylinder 12 below the piston 19 as the piston 19 is approaching the bottom 16 of the cylinder 12. The reduction of cross-sectional area for air to exit is achieved by giving the first part 24 of the piston rod 20 a larger diameter, so that when the first part 24 enters the piston rod sleeve 27 it reduces the area where air can flow compare to when the second part 25 of the piston rod occupies the piston rod sleeve 27. Consequently, the pressure increases in the second cylinder chamber and the speed and force of the piston rod 20 is gradually reduced towards the extended position.

Fig. 5 Shows the striker 11 in a different view but in the same configuration as in figure 4.

Fig. 6 shows the fish stunning device 10 from what will normally be below i.e. in an angle from the fish guide 40.

The example above is only given to illuminate the invention, and obvious modifications and alternative should be included in the scope of invention as defined by the claims.