Visual inspection and sorting system for fresh soybean sorting

Abstract

The invention discloses a visual inspection and sorting system for fresh soybean sorting, which comprises a control device, a vibration sequencing device, a belt conveying device, a visual acquisition device and an airflow nozzle, and is characterized in that the vibration sequencing device and the airflow nozzle are respectively positioned at the feeding end and the discharging end of the belt conveying device; a first conveying channel is arranged on a corrugated plate of the vibration sequencing device; a plurality of annular division bars are arranged on a transparent belt of the belt conveying device, a second conveying channel is formed between the division bars, a surface cleaning device is arranged below the transparent belt, a first visual collecting device is arranged above the position close to the output end of the transparent belt, and a second visual collecting device is arranged on the inner side of an annular space defined by the transparent belt. The visual collection device transmits collected information to the control device, the collected information is processed by the control device, and the airflow nozzle is controlled to classify the fresh soybeans. The system is high in execution response speed and accurate, the airflow pressure of the airflow nozzles is consistent, leakage blowing or mistaken blowing is reduced, and the sorting effect under the high-flux condition is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fresh soybean sorting, and more particularly to a visual inspection and sorting system for fresh soybean sorting. Background Art

[0002] In recent years, the consumption demand for fresh soybeans has gradually increased, and fresh soybeans have higher requirements for overall quality, mainly including size, color, etc. After the fresh soybeans are harvested, they need to be strictly sorted for quality to remove pod materials and impurities that do not meet the requirements.

[0003] At present, the equipment for color sorting of fresh soybeans often adopts flat belt conveyor. The soybeans are spread on the flat belt by the front equipment, and are transported at high speed by the flat belt. They are thrown out at the output end of the conveyor belt by inertia. At the same time, a visual acquisition device is set above the throwing position, and the collected image information is transmitted to the control device in real time. Due to the fast conveying speed of soybeans, the visual acquisition device and the air flow nozzle are located in the same area. The collected fresh soybean information is quickly transmitted to the control device for classification judgment, and then the actuator is controlled to perform the air blowing action. Such a setting method often puts forward high requirements on the processing speed and has a high hardware cost. At the same time, since the airflow nozzle device for classification is also one of the core components of fresh soybean sorting, its main function is to remove unqualified materials and impurities from the whole through high-speed airflow injection, so as to realize the sorting of fresh soybean pod materials. The existing conveying equipment makes the distribution position of materials on it relatively disordered. Since the particle size of impurities and unqualified pod materials is different from that of qualified materials, if the diameter of the airflow nozzle outlet is larger than the material particle size, the high-pressure gas blown out will bring out the materials next to the impurities, which will reduce the production of qualified materials; if the airflow nozzle outlet diameter is small and the distance between adjacent outlets is large, impurities and unqualified materials will not be blown away, reducing the sorting efficiency and quality of fresh soybeans. At the same time, due to the poor boundary sense of the materials on the conveying flat belt, the airflow nozzle outlet position is relatively fixed, and the airflow at the airflow nozzle outlet is divergent, resulting in more misblowing, which seriously affects the sorting accuracy of fresh soybeans. Summary of the invention

[0004] In view of the fact that the visual acquisition and air flow nozzle in the prior art are simultaneously located above the material throwing trajectory, higher requirements are put forward on the data processing speed and the response capability of the actuator, resulting in high hardware costs. At the same time, there are technical problems such as low air blowing accuracy of the air flow nozzle and weak pulse jet air flow pressure. The present invention provides a visual inspection and sorting system for soybean sorting, in which dividing strips are arranged on the conveyor belt and upper and lower visual acquisitions are performed, and air blowing is performed at the throwing trajectory. By optimizing the air nozzle structure, leaking or misblowing is reduced, and the air flow pressure is consistent, thereby improving the sorting effect under high throughput conditions.

[0005] The technical solutions adopted are as follows:

[0006] A visual inspection and sorting system for sorting fresh soybeans, comprising a control device and a vibration sorting device electrically connected to the control device, a belt conveyor device, a visual collection device, and an airflow nozzle, wherein the vibration sorting device is arranged at the feeding end of the belt conveyor device, and the airflow nozzle is arranged at the output end of the belt conveyor device. The vibration sorting device comprises a corrugated plate, and a plurality of first conveying channels arranged along the conveying direction are arranged on the corrugated plate. The belt conveyor device comprises an annular transparent belt, and a plurality of longitudinally arranged annular partitions are arranged on the conveying surface of the transparent belt, and a second conveying channel is formed between two adjacent partitions, and the width of the second conveying channel is slightly larger than that of the soybeans. The widest size of the pod, the first conveying channel and the second conveying channel are in one-to-one correspondence front to back; a surface cleaning device for cleaning the second conveying channel is provided at the lower rotation part of the transparent belt, and the surface cleaning device is electrically connected to the control device; a fill light and a first visual collection device are provided above the output end of the transparent belt, and a second visual collection device is provided inside the annular space surrounded by the transparent belt, the first visual collection device and the second visual collection device synchronously collect information of the upper and lower surfaces of the fresh soybeans, and transmit the collected information to the control device, and the control device classifies the fresh soybeans according to the collected information by controlling the airflow nozzle.

[0007] Furthermore, the first visual acquisition device and the second visual acquisition device are arranged opposite to each other in an upper and lower position, and synchronously acquire information of the upper and lower surfaces of the same fresh soybean, and synchronously transmit the information to the control device for processing.

[0008] Furthermore, a plurality of groups of first visual acquisition devices are arranged in a front-to-back manner along the conveying direction of the transparent belt, and a plurality of groups of second visual acquisition devices are arranged in a front-to-back manner in the annular space formed by the transparent belt. The plurality of groups of first visual acquisition devices and the plurality of groups of second visual acquisition devices are arranged in a one-to-one correspondence or staggered manner.

[0009] Preferably, the partition bar is a transparent partition bar with a herringbone-shaped cross section.

[0010] Furthermore, the air flow nozzle includes a nozzle body, one end face of the nozzle body is provided with a plurality of air inlets, and the other end face thereof is provided with a plurality of air outlets arranged in a line and corresponding one-to-one with the second conveying channel, the jet direction of the air outlet is 30° to 90° with the soybean throwing path, the air inlet and the air outlet are connected one-to-one through a smooth air flow channel, the front end of the air flow channel is provided with a contraction tube, a throat and a gradually expanding tube in sequence along the air flow direction, both ends of the throat are transitioned to the contraction tube and the gradually expanding tube by arcs, and the outlet end of the gradually expanding tube extends to the air outlet with a constant inner diameter.

[0011] Furthermore, the airflow nozzles are arranged in two front and rear groups side by side along the soybean throwing path, a grading partition is provided below the soybean throwing path, and the two groups of airflow nozzles are respectively located on both sides of the grading partition.

[0012] Furthermore, the inner diameter of the throat is 1 mm, the length of the throat is 0.5 to 1 times the inner diameter of the throat, the length of the contraction tube is 3 to 5 times the inner diameter of the throat, the tapering angle of the contraction tube is 30° to 45°, and the expansion angle of the expansion tube is 8° to 12°.

[0013] Preferably, the inner diameter of the air inlet is 4 mm, and the inner diameter of the air outlet is 2-3 mm.

[0014] Preferably, two rows of staggered air inlets are provided on the air inlet end surface of the nozzle body.

[0015] Further preferably, the surface cleaning device includes a cleaning brush, a support rod, a guide slide groove, a first crank, a second crank and a rotating servo, the cleaning brush is provided with bristles corresponding one to one with the second conveying channel on the transparent belt, the support rod is vertically arranged on the lower end surface of the cleaning brush and penetrates the guide slide groove up and down, the guide slide groove is vertically fixed under the transparent belt, one end of the first crank is hinged to the outer side of the lower end of the support rod, the other end of the first crank is hinged to one end of the second crank, the other end of the second crank is rotationally connected to the rotating servo, and a crank-connecting rod mechanism is formed between the rotating servo, the first crank, the second crank and the support rod.

[0016] The technical solution of the present invention has the following advantages:

[0017] A. The system of the present invention adopts a transparent belt structure with a plurality of annular conveying channels. The materials are laid flat on the first conveying channel after vibration sorting, and then fall on the corresponding second conveying channel in sequence. Due to the transparent structure of the second conveying channel, the first visual acquisition device and the second visual acquisition device arranged above and below directly correspond to collect the upper and lower side information of the fresh soybean pods in the same area, and transmit it to the control device. After processing, the air flow channel located in the throwing area is controlled to perform air blowing classification. The visual acquisition device and the air flow nozzle are located in two different areas, which can well alleviate the relationship between data processing and execution response, have relatively low requirements for hardware processing, and can achieve high-throughput processing efficiency.

[0018] B. The present invention arranges a contraction tube, a throat tube and a gradually diverging tube in the air flow channel of the air flow nozzle, so that the air flow direction at the nozzle outlet edge and the middle area remains consistent, and the pressure is uniform, and an air atomization effect is formed at each air outlet. Combined with each transparent conveying channel, the air flow can be accurately applied to the middle area of ​​the fresh soybean pods, and the explosive atomized air flow is more conducive to improving the sorting effect under high throughput conditions.

[0019] C. The present invention is provided with two groups of air flow nozzles, which can classify different defects. The multi-layer air inlet is arranged so that the number of air outlets corresponds to the number of air inlets, thereby reducing the distance between the air outlets, and there is no obvious difference between adjacent air outlet channels, so that the material rejection angle can be relatively consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a front view of the overall structure of the system provided by the present invention;

[0022] Figure 2 yes Figure 1 A three-dimensional diagram of the structure shown;

[0023] Figure 3a It is a principle diagram of a hierarchical detection system composed of a group of first visual acquisition devices, a group of second visual acquisition devices and two groups of airflow nozzles provided by the present invention;

[0024] Figure 3b It is a principle diagram of a hierarchical detection system composed of two groups of first visual acquisition devices, two groups of second visual acquisition devices and two groups of airflow nozzles provided by the present invention;

[0025] Figure 4is a three-dimensional diagram of the airflow nozzle provided by the present invention;

[0026] Figure 5 yes Figure 4 Perspective view shown;

[0027] Figure 6 yes Figure 4 The intake end view is shown;

[0028] Figure 7 yes Figure 6 AA section view shown;

[0029] Figure 8 yes Figure 6 The BB section view is shown;

[0030] Fig. 9 yes Figure 1 A view of the surface cleaning device shown in;

[0031] Fig.10 It is a FLUENT simulation pressure cloud diagram of the gas nozzle of the present invention.

[0032] The symbols provided in the figure are explained as follows:

[0033] 1-Power supply; 2-Vibration motor

[0034] 3-Corrugated board

[0035] 31-First conveying channel

[0036] 4-Transfer conveying chute

[0037] 5-Conveyor motor

[0038] 6- Transparent belt

[0039] 61- second conveying channel, 62- partition bar

[0040] 7-Rack

[0041] 8-Surface cleaning device

[0042] 81-Cleaning Brush

[0043] 811-Brush

[0044] 82-support rod, 83-guide slot, 84-first crank, 85-second crank

[0045] 86-Rotate the servo

[0046] 9-air flow nozzle, 9a-first air flow nozzle, 9b-second air flow nozzle

[0047] 91-Nozzle body

[0048] 92-Airflow channel

[0049] 921-contracting tube, 922-throat tube, 923-expanding tube

[0050] 10-control device; 11-first visual acquisition device; 12-finished product discharge port

[0051] 13- grading partition; 14- second visual acquisition device; 15- defect discharge port.

[0052] a-air inlet, b-air outlet; c-soybean throwing path. DETAILED DESCRIPTION

[0053] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] like Figure 1 and Figure 2As shown, the present invention provides a visual inspection and sorting system for sorting fresh soybeans, comprising a control device 10 and a vibration sorting device electrically connected to the control device 10, a belt conveyor device, a visual collection device, and an airflow nozzle 9, wherein the vibration sorting device is arranged at the feed end of the belt conveyor device, and the airflow nozzle 9 is arranged at the output end of the belt conveyor device. The vibration sorting device comprises a vibration motor 2 and a corrugated plate 3, wherein a plurality of first conveying channels 31 arranged along the conveying direction are arranged on the corrugated plate 3, and a transfer conveying chute 4 is connected to the outlet end of the corrugated plate, and a corrugated groove is also arranged on the transfer conveying chute 4; the belt conveyor device comprises a conveying motor 5 and an annular transparent belt 6, wherein the conveying motor 5 drives the transparent belt 6 to perform annular conveying, and a plurality of annular partitions 62 arranged along the conveying direction are arranged on the conveying surface of the transparent belt 6, and a second conveying channel 61 is formed between two adjacent partitions 62, and the partitions 62 are preferably transparent partitions with a herringbone cross section. The width of the second conveying channel 61 is slightly larger than the widest dimension of the bean pod, and the first conveying channel 31 and the second conveying channel 61 correspond one to one in front and back; a surface cleaning device 8 for cleaning the second conveying channel 61 is provided at the lower turning point of the transparent belt 6, and the surface cleaning device 8 is electrically connected to the control device 10; a fill light and a first visual collection device 11 are provided above the output end of the transparent belt 6, and the fill light (not shown in the figure) is provided inside the first visual collection device 11 to illuminate the collection area, and a second visual collection device 14 is provided inside the annular space surrounded by the transparent belt 6, and the first visual collection device 11 and the second visual collection device 14 synchronously collect information of the upper and lower surfaces of the fresh soybeans, and transmit the collected information to the control device 10, and the control device 10 classifies the fresh soybeans by controlling the airflow nozzle 9 according to the collected information. Of course, multiple visual collection devices can also be provided along the conveying direction of the transparent belt, such as Figure 3b As shown, two front and rear groups of first visual acquisition devices are arranged above the transparent belt, and two front and rear groups of second visual acquisition devices corresponding thereto are arranged in the annular area formed by the transparent belt. Of course, the first visual acquisition devices and the second visual acquisition devices arranged above and below can also be staggered. By using multiple independent groups of visual acquisition devices, cameras and spectra with corresponding performances can be selected according to different collected data, so as to collect multi-dimensional data of fresh soybeans, realize the collection and data processing of different information data such as the inside and outside of fresh soybeans, quickly complete the detection of various defects of fresh soybeans, and control the airflow nozzles to perform classification according to the fullness, size, maturity, etc. of the pods.

[0055] like Figure 1As shown, in the present invention, the first visual acquisition device 11 and the second visual acquisition device 14 are arranged in an upper and lower relative manner, respectively arranged on the upper and lower sides of the transparent belt 6, to synchronously acquire information on the upper and lower sides of the same fresh soybean, and synchronously transmit the information to the control device 10 for processing. The present invention arranges two visual acquisition devices and airflow nozzles in two different areas, moves the visual acquisition device forward to the conveying position of the transparent belt, and performs multi-dimensional visual acquisition of the material on the transparent belt. The airflow nozzle as the execution component is located at the output end of the transparent belt, and the collected fresh soybean data is directly transmitted to the control device, and then the collected visual data is pre-processed, analyzed and classified by the data analysis and processing module in the control device, and the signal of the fresh soybean with defects is transmitted to the airflow nozzle of the execution component, which can well ease the relationship between data processing and execution response, has relatively low requirements for hardware processing, and can achieve high-throughput processing efficiency.

[0056] like Figures 4 to 7 As shown, the airflow nozzle 9 includes a nozzle body 91 and an airflow channel 92 arranged inside the nozzle body 91. One end face of the nozzle body 91 is provided with a plurality of air inlets a, and the other end face thereof is provided with a plurality of air outlets b arranged in a line and corresponding one to one with the second conveying channel 61. The jet direction of the air outlets b is 30° to 90°, preferably 60°, with respect to the soybean throwing path. The air inlets a and the air outlets b are connected one to one through a smooth airflow channel 92. The front end of the airflow channel 92 is provided with a contraction tube 921, a throat 922 and a gradually expanding tube 923 in sequence along the airflow direction. Both ends of the throat 922 are transitioned to the contraction tube 921 and the gradually expanding tube 923 in circular arcs. The outlet end of the gradually expanding tube 923 extends to the air outlet b with a constant inner diameter. As shown Figure 3a and Figure 3b As shown, the airflow nozzles 9 in the present invention are provided with two groups, and two groups are arranged side by side along the soybean delivery path c, namely the first airflow nozzle 9a and the second airflow nozzle 9b. A grading partition 13 is provided below the soybean delivery path c. The two groups of airflow nozzles 9 are respectively located on both sides of the grading partition 13. The first airflow nozzle 9a and the second airflow nozzle 9b perform different pod classifications. For example, the first airflow nozzle 9a performs the removal of fresh soybeans with external defects, and the second airflow nozzle 9b performs the removal of fresh soybeans with internal defects. Of course, it is not limited to the two functions mentioned above. The provision of two rows of airflow nozzles can significantly improve the removal efficiency of defective materials and avoid problems such as leakage and blowing. Of course, more than three groups of airflow nozzles can be provided, which will not be repeated here.

[0057] For the airflow nozzle, in the present invention, the inner diameter of the throat 922 is preferably set to 1 mm, the length of the throat 922 is 0.5 to 1 times the inner diameter of the throat 922, the length of the contraction tube 921 is 3 to 5 times the inner diameter of the throat 922, the contraction angle of the contraction tube 921 is 30° to 45°, and the expansion angle of the expansion tube 923 is 8° to 12°. The inner diameter of the preferred air inlet a is 4 mm, and the inner diameter of the preferred air outlet b is 2 to 3 mm.

[0058] The present invention has carried out the air pressure simulation test on the air flow nozzle, such as Fig.10 The grayscale image of the pressure cloud map shown in the figure shows that the outlet pressure of the airflow nozzle of the present invention is uniform and has good directional consistency, and there is no obvious pressure difference between adjacent airflow channels. In practical application, an air atomization effect is formed at each air outlet, and combined with each transparent conveying channel, the airflow can be accurately applied to the middle area of ​​the fresh soybean pods. The explosive atomized airflow is more conducive to improving the sorting effect under high throughput conditions. The blown airflow is not limited to one point, but an area on the pod, and will not cause any damage to the pod.

[0059] In order to make the air outlets b correspond to each soybean throwing path c one by one and avoid technical problems such as misblowing, the present invention provides at least two rows of air inlets a arranged in a staggered manner on the air inlet end surface of the nozzle body 91. Figure 4 Two rows of staggered air inlets a are arranged in the middle. Since the inner diameter of the air outlet is smaller than that of the air inlet a, the air outlet b is distributed in a straight line. This distribution method is suitable for the case where the distance between two adjacent second conveying channels is small.

[0060] like Fig. 9 As shown, the surface cleaning device 8 adopted in the present invention includes a cleaning brush 81, a support rod 82, a guide chute 83, a first crank 84, a second crank 85 and a rotating servo 86. The cleaning brush 81 is provided with bristles 811 which correspond one to one with the second conveying channel 61 on the transparent belt 6. The support rod 82 is vertically arranged on the lower end surface of the cleaning brush 81 and penetrates the guide chute 83 up and down. The guide chute 83 is vertically fixed below the transparent belt 6. One end of the first crank 84 is hinged to the outer side of the lower end of the support rod 82, and the other end of the first crank 84 is hinged to one end of the second crank 85. The other end of the second crank 85 is rotationally connected with the rotating servo 86. A crank-connecting rod mechanism is formed between the rotating servo 86, the first crank 84, the second crank 85 and the support rod 82. The rotation of the servo engine 86 drives the second crank 85 to rotate, and the second crank drives the first crank 84 to rotate, thereby driving the cleaning brush to move up and down along the guide groove, driving the cleaning brush to move up, and making the bristles contact with the second conveying channel on the lower bottom surface of the transparent belt, so that the second conveying channel can be cleaned in real time during the operation of the transparent belt.

[0061] Of course, the surface cleaning device 8 in the present invention can also adopt a fan suction method. By setting a main pipe connected to the fan suction port, a number of suction nozzles corresponding to the second conveying channel on the lower side of the transparent belt are set on the main pipe. The second conveying channel can also be cleaned through the suction action of the suction nozzles.

[0062] Anything not described in the present invention is applicable to the prior art.

[0063] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A visual inspection and sorting system for sorting fresh soybeans, comprising a control device (10) and a vibration sorting device electrically connected to the control device (10), a belt conveyor device, a visual collection device, and an air flow nozzle (9), wherein the vibration sorting device is arranged at the feed end of the belt conveyor device, and the air flow nozzle (9) is arranged at the output end of the belt conveyor device, characterized in that: The vibration sorting device comprises a corrugated plate (3), on which a plurality of first conveying channels (31) are arranged along a conveying direction; the belt conveying device comprises an annular transparent belt (6), on the conveying surface of the transparent belt (6) a plurality of annular spacers (62) arranged in a longitudinal direction are arranged, and a second conveying channel (61) is formed between two adjacent spacers (62), the width of the second conveying channel (61) is slightly larger than the widest dimension of the bean pod, and the first conveying channel (31) and the second conveying channel (61) correspond to each other front to back; a lower rotating portion of the transparent belt (6) is provided with a cleaning device for cleaning the second conveying channel (61) is provided with a surface cleaning device (8), the surface cleaning device (8) being electrically connected to the control device (10); a fill light and a first visual collection device (11) are provided above the output end of the transparent belt (6); a second visual collection device (14) is provided inside the annular space surrounded by the transparent belt (6); the first visual collection device (11) and the second visual collection device (14) synchronously collect information of the upper and lower surfaces of the fresh soybeans, and transmit the collected information to the control device (10); the control device (10) performs classification of the fresh soybeans by controlling the airflow nozzle (9) according to the collected information.

2. The visual inspection and sorting system for sorting fresh soybeans according to claim 1, characterized in that: The first visual acquisition device (11) and the second visual acquisition device (14) are arranged opposite to each other in an upper and lower position, and synchronously acquire information on the upper and lower surfaces of the same fresh soybean, and synchronously transmit the information to the control device (10) for processing.

3. The visual inspection and sorting system for sorting fresh soybeans according to claim 2, characterized in that: A plurality of groups of first visual acquisition devices (11) are arranged in a front-to-back manner along the conveying direction of the transparent belt (6), and a plurality of groups of second visual acquisition devices (14) are arranged in a front-to-back manner in the annular space formed by the transparent belt (6). The plurality of groups of the first visual acquisition devices (11) and the plurality of groups of the second visual acquisition devices (14) are arranged in a one-to-one correspondence or staggered manner.

4. The visual inspection and sorting system for sorting fresh soybeans according to claim 1, characterized in that: The partition bar (62) is a transparent partition bar with a herringbone-shaped cross section.

5. The visual inspection and sorting system for sorting fresh soybeans according to claim 1, characterized in that: The air flow nozzle (9) comprises a nozzle body (91), wherein one end face of the nozzle body (91) is provided with a plurality of air inlets (a), and the other end face of the nozzle body (91) is provided with a plurality of air outlets (b) arranged in a line and corresponding one to one with the second conveying channel (61), wherein the jetting direction of the air outlets (b) is 30° to 90° with respect to the soybean throwing path (c), wherein the air inlets (a) and the air outlets (b) are connected one to one via a smooth air flow channel (92), wherein a contraction tube (921), a throat tube (922) and a gradually expanding tube (923) are sequentially provided at the front end of the air flow channel (92) along the air flow direction, wherein both ends of the throat tube (922) are transitioned to the contraction tube (921) and the gradually expanding tube (923) in the form of arcs, and the outlet end of the gradually expanding tube (923) extends to the air outlet (b) with a constant inner diameter.

6. The visual inspection and sorting system for sorting fresh soybeans according to claim 5, characterized in that: The airflow nozzles (9) are arranged in two groups, front and rear, along the soybean throwing path (c). A grading partition (13) is provided below the soybean throwing path (c). The two groups of airflow nozzles (9) are respectively located on both sides of the grading partition (13).

7. The visual inspection and sorting system for sorting fresh soybeans according to claim 5, characterized in that: The inner diameter of the throat (922) is 1 mm, the length of the throat (922) is 0.5 to 1 times the inner diameter of the throat (922), the length of the contraction tube (921) is 3 to 5 times the inner diameter of the throat (922), the tapering angle of the contraction tube (921) is 30° to 45°, and the tapering angle of the gradually expanding tube (923) is 8° to 12°.

8. The visual inspection and sorting system for sorting fresh soybeans according to claim 7, characterized in that: The inner diameter of the air inlet (a) is 4 mm, and the inner diameter of the air outlet (b) is 2 to 3 mm.

9. The visual inspection and sorting system for sorting fresh soybeans according to claim 7, characterized in that: The air inlet end surface of the nozzle body (91) is provided with two rows of air inlets (a) arranged in a staggered manner.

10. According to the visual inspection and sorting system for sorting fresh soybeans according to any one of claims 1 to 9, the surface cleaning device (8) comprises a cleaning brush (81), a support rod (82), a guide chute (83), a first crank (84), a second crank (85) and a rotating steering gear (86), the cleaning brush (81) is provided with bristles (811) which correspond one-to-one with the second conveying channel (61) on the transparent belt (6), the support rod (82) is vertically arranged on the lower end surface of the cleaning brush (81) and is vertically arranged. The guide groove (83) runs through the guide groove (83), and the guide groove (83) is vertically fixed below the transparent belt (6). One end of the first crank (84) is hinged to the outer side of the lower end of the support rod (82), and the other end of the first crank (84) is hinged to one end of the second crank (85). The other end of the second crank (85) is rotationally connected with the rotating steering gear (86). A crank-connecting rod mechanism is formed between the rotating steering gear (86), the first crank (84), the second crank (85) and the support rod (82).

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