A dead fish detection and cleaning robot for deep-sea cages

Abstract

The present invention discloses a dead fish detection and cleaning robot for deep-sea cages, which relates to the deep-sea aquaculture and underwater robot operation fields. Ski jumps are respectively arranged on both sides of the entrance of the collection box, and propeller propellers are arranged at the drainage port of the collection box. The drainage port of the propeller propeller and the dead fish collection port are diagonally distributed in the longitudinal direction. When the water flow in the collection box is discharged under the action of the propeller propeller, a negative pressure is formed, and the external water flow is sucked into the dead fish collection port, driving the dead fish at the bottom of the cage to enter the collection port and jump up along the ski jump board and fall into the two sides of the collection box; the waterproof pan-tilt camera and the waterproof binocular camera can monitor the collection operation status in real time. The disclosed technical solution offsets the reverse thrust generated during drainage, greatly improves the motion stability of the underwater robot operation, and has little effect on the fish living at the bottom of the cage, so that the fishing operation of dead fish minimizes the interference to normal aquaculture.

Description

Technical Field

[0001] The invention relates to the field of deep-sea aquaculture and underwater robot operation, and in particular to a dead fish detection and cleaning robot used for deep-sea cages. Background Art

[0002] As my country's marine fishery develops from offshore to deep blue, the demand for underwater robots is increasing. The existing underwater robots used in marine aquaculture are mainly used to detect whether the cages are damaged, observe the aquaculture organisms and monitor the water quality, but the problem of fishing and cleaning the sediments of sick and dead aquaculture organisms has not been solved. If the sick and dead aquaculture organisms in the cages are not removed in time, organic matter will be produced. These organic matter will be decomposed by corrupt anaerobic bacteria at the bottom to produce toxic substances, which will cause great harm to the surviving farmed fish. The toxic gases such as hydrogen sulfide and ammonia produced by decay and deterioration will enter the water body and cause the water quality to deteriorate. At the same time, a large amount of organic matter provides nutrition for pathogens, which take the opportunity to multiply in large numbers, aggravate the disease of fish and threaten the living environment of farmed fish.

[0003] Chinese invention patent 2020116212528, unattended multifunctional underwater robot for deep-sea cages, discloses an unattended multifunctional underwater robot for deep-sea cages. It includes a robot body, a brush-type cage cleaning system, a dead fish collection system, and a cage hole repair system. The robot body includes a robot body shell, a visual system, a robot motion system, and a control system. The visual system, the robot motion system, the control system, and the cage hole repair system are all arranged on the robot body shell. It is used for the maintenance and hole repair of deep-sea cages, cleaning of attachments on the cages, monitoring of the growth status and living environment of farmed organisms in the cages, and fishing and cleaning of sick and dead farmed organisms in the cages. However, the dead fish collection system of the invention only uses the central rod and the collection blades arranged at intervals along the annular outer wall of the central rod. The central rod is driven by a motor to rotate, and the blades on the central rod roll the dead fish into the collection box, thereby realizing the collection of dead fish. The reverse thrust cannot be offset, which greatly affects the fish living at the bottom of the cage, which is not conducive to normal breeding.

[0004] Difficulties in solving technical problems: Traditionally, the cleaning of sick and dead fish mainly relies on divers carrying nets to dive and salvage fish. The single catch is small, the labor intensity is high, and the risk is high. It is not suitable for cleaning operations in large deep-sea aquaculture cages. Domestic underwater fishing robots are mostly used to capture small organisms such as sea cucumbers and sea urchins. Sick and dead fish have smooth surfaces and large bodies, making them difficult to catch and recycle.

[0005] Significance: The dead fish detection and cleaning robot for deep-sea cages can not only complete the cleaning and recovery of dead fish, but also monitor the integrity of the nets. It can completely replace the work of divers, reduce the workload of aquaculture workers, and reduce aquaculture costs. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the disclosed embodiment of the present invention provides a dead fish detection and cleaning robot for deep-sea cages. The technical solution is as follows:

[0007] According to a first aspect of the disclosed embodiments of the present invention, there is provided a dead fish detection and cleaning robot for deep-sea cages, comprising a control unit, a power management unit, and a symmetrically arranged power unit, the dead fish detection and cleaning robot for deep-sea cages also comprising:

[0008] A fishing unit, the fishing unit comprising: a collecting box, ski jumps are respectively arranged on both sides of the entrance of the collecting box, a propeller propeller is arranged at the drainage port of the tail plate of the collecting box, the drainage port of the propeller propeller and the collecting port are diagonally distributed in the longitudinal direction, when the water flow in the collecting box is discharged under the action of the propeller propeller, and negative pressure is formed, the external water flow is sucked into the collecting port, driving the sick and dead fish at the bottom of the net cage to enter the collecting port and jump up along the ski jump board and fall into both sides of the inside of the collecting box;

[0009] The observation and lighting unit comprises: four underwater lighting lamps arranged above the collection box, a waterproof pan-tilt camera and a waterproof binocular camera arranged above the deflector cover.

[0010] In one embodiment, the fishing unit also includes: a deflector cover, which is a channel structure, and the distance between a pair of side walls of the channel structure gradually decreases from the inlet to the outlet. An aluminum round tube is welded at the lower end of the deflector cover to reduce friction with the net.

[0011] In one embodiment, the power unit comprises:

[0012] A waterproof motor, which is arranged on a side surface of the inner protective plate of the crawler and fixed by bolts;

[0013] The crawler moves synchronously with the rotating end of the waterproof motor through a connecting piece.

[0014] In one embodiment, the connector comprises:

[0015] A driving wheel connected to the rotating end of the waterproof motor;

[0016] A crawler connecting bracket, wherein the crawler connecting bracket is connected to the load-bearing plate, the towing plate, the outer crawler protection plate, the inner crawler protection plate and the buoyancy block;

[0017] A driven wheel, the driven wheel is arranged on the inner side protection plate of the crawler and rotates relative to the collection box, and the crawler is meshed with the driving wheel and the driven wheel;

[0018] The load-bearing plate, the load-bearing wheel is arranged at the lower end of the crawler connection bracket and fits with the inner side of the crawler;

[0019] The towing plate is arranged at the upper end of the crawler track connecting bracket and is in contact with the inner side of the crawler track.

[0020] In one embodiment, a drain pipe is provided at the drain outlet of the collection box, a propeller propeller is provided in the drain pipe, and a fish shield is installed at one end of the drain pipe close to the collection box.

[0021] In one embodiment, the observation and illumination unit further comprises:

[0022] An underwater lighting lamp, wherein the underwater lighting lamp is disposed above the collecting box through a top frame, and the light of the underwater lighting lamp is aimed at the forward direction and the backward direction of the robot;

[0023] A waterproof PTZ camera, wherein the PTZ camera is disposed above the collection box through a top frame;

[0024] A waterproof binocular camera is arranged on the upper part of the shroud and is aimed at the forward direction of the robot.

[0025] In one embodiment, the outlet of the collection box is movably connected to a collection box outlet plate, and the collection box outlet plate is connected to the collection box socket via a pin.

[0026] The lighting control module, the fishing control module and the travel control module are all integrated on the circuit board.

[0027] The technical solution provided by the embodiments disclosed in the present invention may have the following beneficial effects: by using underwater robots, it is possible to replace aquaculture workers to complete the salvage of sick and dead fish, collect environmental data of aquaculture water bodies, improve the environment and quality of cage aquaculture water bodies, and effectively protect the marine ecosystem, and achieve sustainable development of fisheries, which is of great significance to the country's promotion of traditional fisheries from offshore to deep blue, specifically:

[0028] First, the shape of the collection box is different from that of the traditional box. It was optimized after calculation using hydrodynamic software during design. A one-way door controlled by a servo is added at the entrance of the collection box. Water flow baffles are set on both sides of the entrance of the collection box. A ski jump is added in the middle of the collection box, so that sick and dead fish can jump up along the ski jump under the drive of the water flow after entering the collection box and fall into the area below the water outlet of the collection box. The shape of the collection box adopts an inverted trapezoidal design. As the collection amount gradually increases, sick and dead fish will gradually fall to the bottom of the box along both sides of the collection box; the top of the collection box is approximately parallel to the ski jump, so that the flow field distribution in the collection box is more reasonable, which is more conducive to the collection of sick and dead fish. At the same time, the collection box is made of acrylic material as a whole, which has good transparency. The waterproof pan-tilt camera fixed on the top frame can monitor the recovery operation status in real time.

[0029] Second, a waterproof motor is used as the actuator of the underwater robot. The waterproof motor drives the driving wheel to rotate to make the crawler run. Considering that the underwater robot of the present invention mainly crawls on the net at the bottom of the cage, it does not need vertical freedom and does not use a propeller propeller as the robot motion actuator.

[0030] Third, the modular design of the power unit is easy to disassemble and repair. The protective plates on both sides of the track can prevent foreign objects from entering the track walking mechanism and affecting the movement performance of the underwater robot. In addition, it can also protect the net to prevent the sharp parts of the track and baffle from scratching the net;

[0031] Fourth, two underwater lights are arranged at the front of the robot, and two underwater lights are arranged at the rear of the robot. They are connected to the top frame through a collar. The four lights are arranged at a certain angle to ensure that the underwater robot has a good field of view when operating. A waterproof pan-tilt camera is arranged on the top frame, which can fully monitor the robot's surrounding environment and the operation process inside the collection box. A waterproof binocular camera is placed on the front side of the collection box and on the top of the shroud. It is fixed to the shroud with bolts and is used to identify sick and dead fish and for visual positioning;

[0032] Fifth, the control unit controls the walking speed of the underwater robot by adjusting the motor speed. When the speeds of the motors on both sides are different, the underwater robot can complete the bow turning action. The control unit is mainly composed of end covers, pressure-resistant shells, control panels, other electronic components and watertight plugs. The control unit is placed in a pressure-resistant cabin, which is cylindrical in shape, has good pressure resistance and can effectively reduce resistance during travel. The control unit circuit is connected to the power units, propeller thrusters, fishing unit servos and power management units on the left and right sides through watertight plugs and cables;

[0033] Sixth, the power management unit is placed in the pressure cabin. It mainly consists of end covers, pressure-resistant shells, transformers, other electronic components and watertight plugs. The power management unit and the control unit are arranged independently, which can effectively reduce the interference between strong and weak electricity and improve the accuracy of electronic devices.

[0034] Seventh, the collection unit is placed in the middle of the underwater robot, and the propeller thruster and the sick and dead fish collection port are arranged diagonally in the longitudinal direction, forming a height difference that is conducive to fishing operations. The tail suction pipe drainage port opens to the left and right sides, which can offset the reverse thrust generated during drainage, greatly improving the motion stability of the underwater robot operation, and has little impact on the fish living at the bottom of the cage, so that the sick and dead fish fishing operation will have the least interference with normal breeding.

[0035] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0037] Figure 1 1 is a first structural schematic diagram of the robot for detecting and cleaning dead fish in deep-sea cages of the present invention;

[0038] Figure 2 2 is a second structural schematic diagram of the robot for detecting and cleaning dead fish in deep-sea cages of the present invention;

[0039] Figure 3 is a partial structural schematic diagram of the power unit of the present invention;

[0040] Figure 4 is a schematic structural diagram of the collection unit of the present invention;

[0041] Figure 5 is a partial cross-sectional view of a collection box of the present invention;

[0042] Figure 6 It is a schematic diagram of the bottom structure of the collection box of the present invention;

[0043] Figure 7 It is a schematic diagram of the structure of the collecting unit part of the present invention;

[0044] Figure 8 It is a schematic structural diagram of the underwater lighting fixture of the present invention;

[0045] Reference numerals:

[0046] In the figure:

[0047] 1. Inner track protection plate; 2. Outer track protection plate;

[0048] 3 tracks; 4 fairings;

[0049] 5. Waterproof binocular camera; 6. Collection box;

[0050] 7 angle steel; 8 control unit;

[0051] 9 underwater lighting; 10 power management unit;

[0052] 11 middle frame; 12 waterproof motor;

[0053] 13 waterproof PTZ camera; 14 top frame;

[0054] 15 driven wheel; 16 load-bearing plate;

[0055] 17 buoyancy block; 18 track connection bracket;

[0056] 19 towing board; 20 driving wheel;

[0057] 21 steering gear and the baffle it drives; 22 drainage pipe;

[0058] 23 tail board; 24 ski jump board;

[0059] 25 inner side panel of the collection box; 26 collection port;

[0060] 27 hinge; 28 collection box bottom plate;

[0061] 29 Collection box jack; 30 Propeller thruster;

[0062] 31 fish shield; 32 welded round tube at the bottom of the deflector;

[0063] 33 underwater lighting fixture a; 34 underwater lighting fixture b;

[0064] 35 underwater lighting fixture fixing clamp c; 36 underwater lighting fixture fixing collar. DETAILED DESCRIPTION

[0065] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0066] The technical solution provided by the disclosed embodiment of the present invention relates to a dead fish detection and cleaning robot for deep-sea cages, and particularly to the field of deep-sea aquaculture and underwater robot operations. In the related art, if the dead and sick farmed organisms in the cages are not removed in time, organic matter will be produced. These organic matters are decomposed by corrupt anaerobic bacteria at the bottom to produce toxic substances, which cause great harm to the surviving farmed fish. Toxic gases such as hydrogen sulfide and ammonia produced by decay and deterioration enter the water body, causing water quality deterioration. At the same time, a large amount of organic matter provides nutrition for pathogens, which take the opportunity to multiply in large numbers, aggravate the disease of fish, and threaten the living environment of farmed fish. Based on this, the technical solution disclosed in the present invention provides a dead fish detection and cleaning robot for deep-sea cages. The robot designed in this article is suitable for large offshore aquaculture cages and deep-sea areas with large wave intensity. It can reduce the labor intensity and danger of fishing and reduce the cost of recovering and catching dead and sick fish.

[0067] like Figures 1 to 8 As shown, the sick and dead fish detection and cleaning robot for deep-sea cages described in the present invention includes five major unit modules, namely a power unit, an observation and lighting unit, a control unit, a power management unit, and a collection unit.

[0068] The power unit includes waterproof motors on both sides and the crawler motion mechanism driven by them. Specifically, it includes the inner protective cover 1 of the crawler, the outer protective cover 2 of the crawler, the crawler 3, the driven wheel 15, the load-bearing plate 16, the crawler connection bracket 18, the buoyancy block 17, the towing plate 19, the driving wheel 20, the waterproof motor 12 and other auxiliary parts. When the underwater robot falls into the net cage, the control unit upper computer sends a control command, which is transmitted to the lower computer through the umbilical cable. The lower computer then sends a command to control the operation of the waterproof motor. The motor then drives the driving wheel 20 to drive the crawler 3 to walk on the net. When walking to the corner of the net cage and turning, the waterproof motors 12 on both sides rotate differentially or reversely to enable the underwater robot to achieve bow turning movement. The inner track protection cover 1, the outer track protection cover 2, the load-bearing plate 16 and the towing plate 19 are connected by bolts through the track connecting bracket 18, the waterproof motor 13 is fixed on the inner side plate of the track, and the rotating shaft is connected to the driving wheel through a key to transmit power.

[0069] The observation and lighting unit includes two cameras, four underwater lights and fixed connectors. Specifically, it includes four underwater lights placed on the top frame of the robot, a waterproof pan-tilt camera 13, and a waterproof binocular camera 5 at the collection port. The two underwater lights on the front side of the robot are mainly used to enhance the light brightness in the robot's forward direction, facilitate the identification of sick and dead fish and the observation of the cage environment, and provide a good field of view for the waterproof binocular camera 5 placed at the collection port 26 to observe the fishing of sick and dead fish in real time;

[0070] It should be further pointed out that the waterproof PTZ camera 13 is fixed to the top frame 14 by bolts, and the observation field is wider, and the waterproof binocular camera 5 is fixed to the guide cover 4 above the collection port of the robot collection unit by bolts;

[0071] It should be further pointed out that the underwater lighting lamp is fixed on the top frame through the underwater lighting lamp fixing ring 33, the underwater lighting lamp fixing clamp a34, the underwater lighting lamp fixing clamp b35, and the underwater lighting lamp fixing clamp c36. The underwater lighting lamp fixing clamp a34 and the underwater lighting lamp fixing clamp b35 are connected and fixed by screws, and the underwater lighting lamp fixing clamp b35 and the underwater lighting lamp fixing clamp c36 are fixed by bolts and the angle between the two is adjustable, which can be manually adjusted according to the underwater environment and light intensity. The two underwater lighting lamps at the tail create lighting conditions for monitoring the operation effect of the sick and dead fish catching robot. It is used together with the waterproof pan-tilt camera 13 arranged on the top frame. The waterproof pan-tilt camera 13 transmits the video image in the collection box 6 to the upper computer screen in real time. The shore-based operator can confirm whether the sick and dead fish are fully collected and the collection status through the video image. In addition, it can also cooperate with the designed algorithm to autonomously judge whether the collection is full. The waterproof binocular camera 5 is placed above the guide cover 4. Its main function is to capture the environmental information of the robot's forward direction in real time and autonomously identify sick and dead fish, perform visual positioning, and ensure that it does not hit the net, avoid damaging the net, and cause farmed fish to escape and cause property losses. In addition, the patency of the collection port 26 can also be observed. When the collection port is blocked by oversized sick and dead fish, making it impossible to continue the operation, first try to move the baffle 21 driven by the waterproof steering gear to push the large-sized sick and dead fish away from their original position. If the blockage cannot be cleared, control the underwater robot to return to the shore for further processing.

[0072] The fishing unit includes a shroud 4 at the front of the robot, a collection box 6 in the middle, a propeller propeller 30, and a drain pipe 22 at the tail. Specifically, it includes a shroud 4, a round tube 32 below the shroud, a steering gear and a baffle 21 driven by the steering gear, a drain pipe 22, a tail plate 23 on the collection box, a ski jump 24, a side plate 25 in the collection box, a collection port 26 of the collection box, a hinge 27, a bottom plate 28 of the collection box, a jack 29 of the collection box, a propeller propeller 30, and a fish shield 31. The specific implementation method is as follows: the lighting and camera unit transmits the video image to the lower computer of the control unit 8 through a cable, and the lower computer then transmits the video signal to the upper computer through a composite umbilical cable. The shore-based operator can perform sick and dead fish fishing operations through manual remote control or the upper computer autonomously running the program. First, turn on the steering engine, control the steering engine to rotate the baffle 21 driven by it counterclockwise to be parallel to the bottom of the net box, then turn on the propeller propeller 30, the propeller propeller 30 starts to rotate, the water flow in the collection box 6 is quickly discharged, forming a negative pressure, the water flow at the deflector 4 and the collection box inlet 26 is sucked in, and the surrounding water body flows to the collection box inlet, and finally the flowing water drives the sick and dead fish at the bottom of the net box into the collection box 44, completing the collection of sick and dead fish. An aluminum round tube 32 is installed below the deflector 4 to prevent scratching the net, and the edges of the deflector 4 are also rounded to make the contact part with the net smooth and free of hooks. A hollow hemispherical fish shield 31 is installed at the drainage pipe outlet of the collection box, which is better than the flat fish shield, and can effectively prevent sick and dead fish from being sucked at the flat fish shield, affecting the drainage efficiency of the propeller propeller and reducing the collection efficiency. The drainage pipe 22 opens to both sides at the same time to offset the thrust generated by the water flow. The observation and lighting unit in the collection box transmits the video images in the collection box to the host computer in real time, and the host computer uses this to determine whether the sick and dead fish are fully collected. If they are fully collected, the propeller propeller is turned off and the steering gear is driven to rotate the baffle 21 driven by it clockwise to be perpendicular to the bottom surface of the net cage. At this time, the entrance of the collection box is closed, and the sick and dead fish detection and cleaning robot starts to return. The sick and dead fish detection and cleaning robot returns to the starting point of the operation autonomously and is lifted by the winch. When the robot is hoisted to 50cm from the ground, the staff pulls out the pin connecting the collection box bottom plate jack and the collection box jack 29, and the collection box bottom plate 28 is opened. At this time, the sick and dead fish and the water in the collection box will fall under the action of gravity and fall into the collection tube prepared in advance. At this point, the single sick and dead fish collection task is completed. The sick and dead fish detection and cleaning robot can repeat the operation many times until all sick and dead fish are cleaned.

[0073] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the disclosure disclosed herein. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

[0074] It should be understood that the present disclosure is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure should be limited by the appended claims.

Claims

1. A dead fish detection and cleaning robot for deep-sea cages, comprising a control unit, a power management unit and a symmetrically arranged power unit, characterized in that: The dead fish detection and cleaning robot for deep-sea cages also includes: A fishing unit, the fishing unit comprising: a collecting box (6), water flow baffles (25) symmetrically arranged on both sides of a collecting port (26) of the collecting box (6), the collecting box (6) being provided with a drainage port (23), a propeller propeller (30) being arranged in the drainage port (23), the drainage port (23) and the collecting port (26) of the collecting box being diagonally distributed in the longitudinal direction, when the water flow in the collecting box is discharged under the action of the propeller propeller (30) and negative pressure is formed, the external water flow is sucked into the collecting port (26), driving the sick and dead fish at the bottom of the net cage to enter the collecting port and then jump upwards along the ski jump (24) and fall into both sides of the inside of the collecting box (6); An observation and lighting unit, the observation and lighting unit comprising: an underwater lighting lamp (9), the underwater lighting lamp being arranged on a top frame (14) and arranged on the upper part of the collection box (6), the light of the underwater lighting lamp being aimed at the forward direction and the backward direction of the robot; A waterproof pan-tilt camera (13), wherein the waterproof pan-tilt camera (13) is arranged above the collection box (6) via a top frame (14); A waterproof binocular camera (5), wherein the waterproof binocular camera (5) is arranged at the front side of the collection box (6) and is aimed at the forward direction of the robot; The fishing unit further comprises: a guide cover (4), the guide cover (4) being a channel structure, the distance between a pair of side walls of the channel structure gradually decreasing from an inlet to an outlet, an aluminum round tube (32) being welded to the lower end of the guide cover (4) to reduce friction with the net; The power unit comprises: A waterproof motor (12), the waterproof motor (12) being arranged on a side surface of the inner side protection plate (1) of the crawler track; A crawler belt (3), wherein the crawler belt (3) moves synchronously with the rotating end of the waterproof motor (12) via a connecting piece; The connecting piece comprises: A driving wheel (20), the driving wheel (20) being connected to a rotating end of the waterproof motor (12); a crawler track connecting bracket (18), the crawler track connecting bracket (18) being connected to a load-bearing plate (16), a towing plate (19), an outer crawler track protection plate (2), an inner crawler track protection plate (1) and a buoyancy block (17); a driven wheel (15), the driven wheel (15) being arranged on the inner crawler track protection plate (1) and rotating relative to the collection box (6), the crawler track (3) being meshed with the driving wheel (20) and the driven wheel (15); A load-bearing plate (16), the load-bearing plate (16) being arranged at the lower end of the crawler track connecting bracket (18) and being in contact with the crawler track (3); A towing plate (19), wherein the towing plate (19) is arranged on the upper end of the crawler track connecting bracket (18) and is in contact with the crawler track (3).

2. A dead fish detection and cleaning robot for deep sea cages according to claim 1, characterized in that: A drainage pipe (22) is provided at the drainage outlet of the collection box, a propeller propeller (30) is provided in the drainage pipe (22), and a fish shield (31) is installed at one end of the drainage pipe (22) close to the collection box.

3. The dead fish detection and cleaning robot for deep-sea cages according to claim 1, characterized in that: The outlet of the collection box (6) is movably connected to a collection box outlet plate (28), and the collection box outlet plate (28) is connected to the collection box socket (29) via a pin.

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