A laboratory fume hood

Abstract

The application discloses a laboratory fume hood, comprising a cabinet body, an exhaust fan, at least one set of tracking type air suction assembly, at least one interception suction port and a target detection sensor. The at least one set of tracking type air suction assembly is arranged on the side wall of the cabinet body and close to the operation port, and the tracking type air suction assembly comprises a main connecting pipe, a secondary connecting pipe and a multi-angle adjustable negative pressure suction nozzle arranged on the secondary connecting pipe. The multi-angle adjustable negative pressure suction nozzle can independently rotate around at least two non-parallel axes in space to change the orientation of the air suction port. The at least one interception suction port is arranged on the operation table top of the cabinet body and is located on the inner side of the operation port to form a bottom intercepted airflow in the area between the two arms of the operator. The target detection sensor is used to sense the position of the operator. Compared with the prior art, the application has the beneficial effects that the capture efficiency is improved, the invalid air suction and airflow self-disturbance are reduced, the airflow barrier of the operation port is maintained stable, and the operator's face breathing area is more effectively protected.

Description

Technical Field

[0001] This invention belongs to the field of fume hood technology, and specifically relates to a laboratory fume hood. Background Technology

[0002] Fume hoods are critical equipment in laboratories to ensure the safety of operators. Their working principle is to create negative pressure inside the hood by using an exhaust fan to draw away harmful gases generated during the experiment from the exhaust vent on the rear wall, while fresh air is introduced from the room through the operating port, forming a main airflow barrier from front to back to prevent toxic gases from escaping from the hood and protect the respiratory safety of operators.

[0003] In practical use, operators need to insert their arms into the operating opening to conduct experiments. The arm itself, as a blunt object, disrupts the original orderly airflow after being inserted into the cabinet, creating vortex zones behind and to the sides of the arm. Some harmful gases can easily escape outwards along these vortex zones, directly impacting the operator's facial breathing area, posing a serious safety threat.

[0004] Therefore, in order to address the aforementioned technical problems, it is necessary to provide a laboratory fume hood. Summary of the Invention

[0005] The purpose of this invention is to provide a laboratory fume hood that can solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides a laboratory fume hood, including a cabinet body and an exhaust fan, and further including at least one set of tracking suction components, at least one intercepting suction port, and a target detection sensor; at least one set of tracking suction components is disposed on the side wall of the cabinet body and near the operating port, the tracking suction components including a main connecting pipe, a secondary connecting pipe, and a multi-angle adjustable negative pressure nozzle mounted on the secondary connecting pipe; the multi-angle adjustable negative pressure nozzle can rotate independently in space around at least two non-parallel axes to change the direction of the suction port; at least one intercepting suction port is opened on the operating surface of the cabinet body, the intercepting suction port is located inside the operating port, and is used to form a bottom intercepting airflow in the area between the operator's arms; the target detection sensor is used to sense the operator's position or arm movements; the multi-angle adjustable negative pressure nozzle and the intercepting suction port are connected to the exhaust fan through pipes, the pipes are provided with a controlled valve, and both the controlled valve and the multi-angle adjustable negative pressure nozzle change their working state according to the signal from the target detection sensor.

[0007] In one or more embodiments of the present invention, the multi-angle adjustable negative pressure nozzle includes a housing, a stator, a rotor, and a negative pressure tube; the stator is fixed to the inner wall of the housing, the rotor is fixed to the negative pressure tube, the negative pressure tube is rotatably connected to the inside of the housing, and the stator drives the rotor to rotate, forcing the negative pressure tube to rotate 360° around its own axis.

[0008] In one or more embodiments of the present invention, the multi-angle adjustable negative pressure nozzle further includes a second negative pressure tube, the front end of the first negative pressure tube is provided with a ball groove, and a ball matching the ball groove is fixedly connected to the second negative pressure tube; the ball and the ball groove are rotatably engaged to form a kinematic pair that only allows the second negative pressure tube to perform up and down pitching motion relative to the first negative pressure tube, wherein the axis of the pitching motion is not parallel to the axis of the 360° rotation.

[0009] In one or more embodiments of the present invention, a slip ring is rotatably connected to the inner wall of the outer shell, and an electric push rod is hinged between the slip ring and the second negative pressure tube; the electric push rod drives the second negative pressure tube to pitch around the center of the ball groove by extension and retraction, so as to cover different suction ranges.

[0010] In one or more embodiments of the present invention, a horizontally extending air guide ridge is provided on the rear wall of the cabinet opposite to the operating port; an upper exhaust air area is formed above the air guide ridge and a lower exhaust air area is formed below the air guide ridge; an independent exhaust port adjustment mechanism is installed at the opening of the upper exhaust air area and the lower exhaust air area to dynamically distribute the upper and lower exhaust air volume.

[0011] In one or more embodiments of the present invention, the target detection sensor includes an ultrasonic sensor for detecting the operator's state; it also includes a temperature sensor and a VOC sensor disposed inside the cabinet; when the VOC sensor detects a signal exceeding a threshold, the exhaust port adjustment mechanism of the lower exhaust zone increases its opening, and at the same time, the controlled valve of the intercepting suction port opens.

[0012] In one or more embodiments of the present invention, the interception suction port is a linear slit opened on the operating table, and its bottom is connected to the exhaust fan through an air supply pipe II, and an electromagnetic valve III is installed on the air supply pipe II.

[0013] In one or more embodiments of the present invention, the upper and lower ends of the main connecting pipe are rotatably connected to the cabinet through bearing two, and the lower end of the main connecting pipe is connected to the gas supply pipe one through a rotary joint.

[0014] In one or more embodiments of the present invention, the multi-angle adjustable negative pressure nozzle and the secondary connecting tube are detachably connected.

[0015] In one or more embodiments of the present invention, the secondary connecting pipes are distributed vertically along the main connecting pipe, and each secondary connecting pipe is equipped with a solenoid valve.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: it can actively identify airflow disturbances caused by the operator's arm intervention and directionally capture the gas escaping around the arm; it can intercept the dynamic pocket area between the two arms at the source; it can perform stratified exhaust according to the rising, sinking or mixing movement trend of polluted gas; it can reduce ineffective exhaust and airflow self-disturbing while improving the capture efficiency, maintain the stability of the airflow barrier at the operating port, and thus more effectively protect the operator's facial breathing area. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a laboratory fume hood according to one embodiment of the present invention. Figure 1 ;

[0019] Figure 2 This is a schematic diagram of the structure of a laboratory fume hood according to one embodiment of the present invention. Figure 2 ;

[0020] Figure 3 This is a partial cross-sectional view of a laboratory fume hood according to an embodiment of the present invention;

[0021] Figure 4 for Figure 3 Schematic diagram of the structure at point A in the middle;

[0022] Figure 5 This is a schematic diagram of the structure of a tracking suction assembly in one embodiment of the present invention;

[0023] Figure 6 This is a cross-sectional view of a multi-angle adjustable negative pressure suction nozzle according to an embodiment of the present invention;

[0024] Figure 7 for Figure 6 Schematic diagram of the structure at point B.

[0025] Explanation of key figure labels:

[0026] 1. Cabinet; 2. Exhaust fan; 3. Air guide ridge; 4. Upper exhaust zone; 5. Lower exhaust zone; 6. Exhaust outlet adjustment mechanism; 7. Tracking suction assembly; 8. Main connecting pipe; 9. Secondary connecting pipe; 10. Solenoid valve one; 11. Multi-angle adjustable negative pressure nozzle; 12. Housing; 13. Stator; 14. Rotor; 15. Negative pressure pipe one; 1501. Ball groove; 16. Bearing one; 17. Negative pressure pipe two; 1701. Ball; 18. Electric push rod; 19. Slip ring; 20. Rubber protective sleeve; 21. Bearing two; 22. Drive motor; 23. Rotary joint; 24. Air supply pipe one; 25. Solenoid valve two; 26. Interception suction port; 27. Air supply pipe two; 2701. Solenoid valve three; 28. Air supply pipe three; 29. ​​Ultrasonic sensor; 30. Temperature sensor; 31. VOC sensor. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0028] like Figures 1-2 As shown, a laboratory fume hood according to one embodiment of the present invention includes a cabinet body 1 and an exhaust fan 2 installed on the top of the cabinet body 1. An operating opening is formed on the front side of the cabinet body 1 for the operator to reach in and perform experimental operations. An operating cavity is formed inside the cabinet body 1 for placing experimental glassware, reagent containers, or heating devices. The exhaust fan 2 is used to create a main airflow within the cabinet body 1 that enters through the operating opening and exits towards the rear and top of the cabinet body 1, thus confining harmful gases inside the cabinet body 1 and discharging them through the exhaust system.

[0029] A guide ridge 3 is provided on the rear wall of cabinet 1, opposite the operating port. The guide ridge 3 is preferably a strip-shaped protrusion extending laterally along the width of cabinet 1, and its cross-section can be triangular, arc-shaped, trapezoidal, or wedge-shaped with a smoothly rounded leading edge. An upper exhaust zone 4 is formed above the guide ridge 3, and a lower exhaust zone 5 is formed below it. Both the upper and lower exhaust zones 4 and 5 are provided with exhaust openings, and both openings are equipped with an exhaust port adjustment mechanism 6. The exhaust port adjustment mechanism 6 can be an electric louvered valve, an electric flap valve, a sliding baffle, or a servo-driven opening adjustment plate, which dynamically distributes the upper and lower exhaust volumes by changing the effective flow area of ​​the upper and lower exhaust ports.

[0030] Specifically, the guide ridge 3 is used to form a passive stratification boundary at the rear of the cabinet 1. When there is a lighter, hotter airflow inside the cabinet, the hotter airflow tends to rise and enter the upper exhaust zone 4 along the guide ridge 3; when there is a denser organic solvent vapor or cold, heavy gas inside the cabinet, these gases are more likely to flow along the vicinity of the tabletop and enter the lower exhaust zone 5 below the guide ridge 3. The guide ridge 3 divides the airflow path through solid protrusions, allowing pollutant air masses of different densities and temperatures to obtain a clearer flow direction boundary at the rear wall. The advantage of setting the guide ridge 3 is that it can reduce the mutual entrainment and mixing of light and heavy airflows at the rear wall, allowing the suction energy of the exhaust fan 2 to be more concentrated on the pollutant air masses at the corresponding height.

[0031] like Figures 1-5 As shown, a set of tracking suction components 7 are respectively installed on both sides of the cabinet 1 near the operation port. The tracking suction components 7 cooperate with the target detection sensors installed inside the cabinet 1. The target detection sensors include an ultrasonic sensor 29, as well as a temperature sensor 30 and a VOC sensor 31. The ultrasonic sensor 29 can be installed on the upper edge, side wall, or inner top plate of the cabinet 1 near the operation port, with its detection direction facing the area where the operator's arm enters, to obtain the change in distance between the operator's arm or body and the cabinet 1. The temperature sensor 30 can be a thermocouple, thermistor, or infrared temperature sensor to detect whether there is a hot plume generated by the heating experiment inside the cabinet 1. The VOC sensor 31 can be a PID photoionization detector, metal oxide semiconductor gas sensor, or electrochemical organic gas sensor to detect the concentration of volatile organic compounds.

[0032] Each set of tracking suction components 7 is equipped with multiple independently adjustable multi-angle negative pressure nozzles 11, which can be adjusted according to the actual position of the operator's arms so that the nozzles are always aimed at the escaping air areas on both sides of the arms for targeted suction. At the same time, an intercepting suction port 26 extending in the left and right direction is opened in the middle of the operating table near the operating port. The intercepting suction port 26 is located directly below the semi-enclosed area formed after the operator's arms are inserted, and is used to intercept and suck up the escaping air in the area from the bottom.

[0033] There are two sets of tracking suction components 7, located on the left and right sides of the cabinet 1 respectively. Each set faces the area where the operator's arms might enter. Each set of tracking suction components 7 includes a main connecting pipe 8, multiple auxiliary connecting pipes 9, and a multi-angle adjustable negative pressure nozzle 11 mounted on the auxiliary connecting pipes 9. The main connecting pipe 8 is arranged vertically, and its upper and lower ends are rotatably connected to the cabinet 1 via bearings 21. Bearings 21 can be installed in bearing seats inside the side wall of the cabinet 1. The bearing seats are fixed to the frame of the cabinet 1 by screws, riveting, or welding, allowing the main connecting pipe 8 to rotate relative to the cabinet 1 while maintaining a sealed connection.

[0034] The lower end of the main connecting pipe 8 is connected to the first air supply pipe 24 via a rotary joint 23. The first air supply pipe 24 is further connected to the third air supply pipe 28, and the output end of the third air supply pipe 28 is connected to the exhaust fan 2. The rotary joint 23 is used to solve the problems of pipe entanglement and seal failure when the main connecting pipe 8 rotates. When the main connecting pipe 8 adjusts its angle with the tracking suction assembly 7, the rotary joint 23 maintains the continuity of the internal negative pressure channel, so that the nozzle orientation adjustment and negative pressure delivery do not interfere with each other.

[0035] The cabinet 1 is equipped with a drive motor 22 for driving the main connecting pipe 8 to rotate.

[0036] Multiple auxiliary connecting pipes 9 are spaced apart along the vertical direction of the main connecting pipe 8, and each auxiliary connecting pipe 9 is connected to the main connecting pipe 8. The auxiliary connecting pipes 9 can be short straight pipes, bends, or branch pipes with locally enlarged diameter sections. One end is fixedly or detachably connected to the main connecting pipe 8, and the other end is equipped with a multi-angle adjustable negative pressure nozzle 11. Each auxiliary connecting pipe 9 is equipped with a solenoid valve 10, which is used to individually control the opening and closing of the corresponding height nozzle. With this setting, the system can open only one or more multi-angle adjustable negative pressure nozzles 11 adjacent to the operator's arm, based on the actual height of the operator's arm, avoiding ineffective airflow consumption caused by all nozzles being open simultaneously. In actual use, when the sensor detects that the operator's arm is mainly at the middle height, the solenoid valves 10 on the upper and lower auxiliary connecting pipes 9 can be closed, opening only the middle auxiliary connecting pipe 9, concentrating the negative pressure at the location most likely to dissipate.

[0037] Specifically, based on the installation height of each multi-angle adjustable negative pressure nozzle 11 and its corresponding capture function, they can be divided into upper zone nozzles, middle zone nozzles, and lower zone nozzles. The setting height of the middle zone nozzle corresponds to the main height range of the operator's arm when the operator's arm is inserted into the cabinet 1 for experimental operations, and its suction port is configured to face the escaping areas on both sides of the operator's arm. When the operator's arm blocks the main airflow from front to back inside the cabinet 1, some polluting gas easily overflows along the outside of the arm or the gap between the arm and the edge of the operating port. The middle zone nozzle, through the selective opening of the solenoid valve 10 and the adjustment of the azimuth and pitch angles of the multi-angle adjustable negative pressure nozzle 11, can directly point to this core escaping area, thereby pinpointing and intercepting the escaping gas caused by the arm's obstruction.

[0038] The upper suction nozzle is located above the middle suction nozzle, with its inlet tilted upwards relative to the horizontal direction, or adjusted to a tilted position facing the area above the arm under the control of the controller. After the operator's arm is inserted into the cabinet 1, the arm itself will partially obstruct the original main airflow, and some gas will be diverted upwards by the disturbance of the arm, possibly escaping along the upper part of the operating port or near the operator's chest and abdomen. The upper suction nozzle, through its higher position and upward tilted suction direction, can assist in capturing this rising diverted gas, so that polluted gas that might have escaped beyond the upper edge of the arm is drawn into the secondary connecting pipe 9 before entering the operator's breathing zone.

[0039] The lower suction nozzle is located below the middle suction nozzle, with its intake tilted downwards relative to the horizontal direction, or adjusted by the controller to be tilted towards the area near the work surface. There is usually a narrow gap between the operator's arm and the work surface, allowing denser organic solvent vapors or contaminant gases that settle due to arm disturbance to easily adhere to the work surface and roll towards the operator's intake along this gap. The lower suction nozzle, with its lower position and downward tilt, can capture the settling gases that divert along the arm and may adhere to the work surface, reducing the chance of slow diffusion of contaminant gases within the work surface boundary layer.

[0040] Through the coordinated operation of the upper, middle, and lower suction nozzles, the tracking suction assembly 7 forms a layered, three-dimensional capture zone across the entire height range where the operator's arm might be present. Specifically, the middle suction nozzle is responsible for targeted capture of the core escaping air areas on both sides of the arm; the upper suction nozzle is responsible for supplementing the capture of rising and diverted air after arm disturbance; and the lower suction nozzle is responsible for supplementing the capture of descending air below the arm and near the work surface. This layered arrangement ensures that the tracking suction assembly 7 does not merely create a localized negative pressure at a single height, but rather forms a continuous, complementary capture zone around the operator's arm. This improves the completeness of capturing contaminated air near the operating port without increasing the overall exhaust volume, and further reduces the risk of escaping due to operator arm intervention.

[0041] Preferably, the upper, middle, and lower suction nozzles can each correspond to different default pitch angle ranges. For example, the default pitch angle of the upper suction nozzle can be set to 5° to 35° upwards, the default pitch angle of the middle suction nozzle can be set to -10° to 10° relative to the horizontal direction, and the default pitch angle of the lower suction nozzle can be set to 5° to 35° downwards. After receiving the arm position signal from the ultrasonic sensor 29, the controller can prioritize opening the middle suction nozzle, which is closest to the arm height, and selectively open the upper or lower suction nozzle based on the detection results of the temperature sensor 30 and the VOC sensor 31. When the temperature sensor 30 detects an increase in the thermal plume, the controller increases the opening ratio of the upper suction nozzle; when the VOC sensor 31 detects an increase in the concentration of heavy organic vapors, the controller increases the opening ratio of the lower suction nozzle.

[0042] A quick-connector is provided between the secondary connecting pipe 9 and the main connecting pipe 8. The quick-connector can be a snap-fit, threaded, or clamp-type connection, and a fluororubber sealing ring is provided at the connection point. This detachable structure facilitates the cleaning, replacement, or disinfection maintenance of the multi-angle adjustable negative pressure nozzle 11, and is especially suitable for experimental environments where organic solvent crystals, dust particles, or corrosive condensates are easily adhered.

[0043] like Figures 1-7 As shown, the multi-angle adjustable negative pressure nozzle 11 includes a housing 12, a stator 13, a rotor 14, and a negative pressure tube 15. The housing 12 is preferably cylindrical, with its rear end connected to the auxiliary connecting pipe 9. Its interior forms a mounting cavity to accommodate the stator 13, rotor 14, and negative pressure tube 15. The stator 13 is fixed to the inner wall of the housing 12, and the rotor 14 is fixed to the outer periphery of the negative pressure tube 15. The negative pressure tube 15 is rotatably connected inside the housing 12 via a bearing 16. The stator 13 and rotor 14 constitute a drive structure similar to a brushless motor or torque motor. When the stator 13 is energized, it generates a rotating magnetic field, driving the rotor 14 to rotate the negative pressure tube 15 360° around its own axis.

[0044] By using stator 13 and rotor 14 to make the suction nozzle itself a controllable rotating component, the suction port can select the most suitable direction according to the change of arm position. Since the negative pressure pipe 15 can remain stationary after being adjusted, its suction direction forms a stable angle with the main airflow direction in the cabinet, which will not continuously tear the airflow barrier of the operating port like a periodically oscillating suction nozzle, thus reducing the self-interference phenomenon of the suction nozzle.

[0045] Negative pressure tube 15 is rotatably connected to negative pressure tube 17 at its front end. A ball groove 1501 is provided at the front end of negative pressure tube 15, and a ball 1701 matching the ball groove 1501 is fixedly connected to negative pressure tube 17. The ball 1701 is embedded in the ball groove 1501, forming a rotational fit between the two and maintaining internal airflow. To ensure that negative pressure tube 17 only moves up and down relative to negative pressure tube 15, the ball groove 1501 can be provided with a limiting groove, guide rib, or a corresponding limiting plane. The ball 1701 is provided with a corresponding limiting pin, guide notch, or anti-rotation surface, restricting lateral sway and free roll of this kinematic pair, allowing only negative pressure tube 17 to rotate around a pitch axis that is not parallel to the axis of negative pressure tube 15. In other words, the multi-angle adjustable negative pressure nozzle 11 simultaneously possesses azimuth and pitch angle adjustment capabilities, enabling independent rotation around at least two non-parallel axes.

[0046] A slip ring 19 is rotatably connected to the inner wall of the outer casing 12. An electric push rod 18 is hinged between the slip ring 19 and the negative pressure tube 17. One end of the electric push rod 18 is hinged to the slip ring 19, and the other end is hinged to the negative pressure tube 17. When the electric push rod 18 extends, it pushes the negative pressure tube 17 to tilt to one side around the center of the ball groove 1501; when the electric push rod 18 retracts, the negative pressure tube 17 swings back in the opposite direction. The function of the slip ring 19 is that when the negative pressure tube 15 drives the negative pressure tube 17 to rotate 360°, the electric push rod 18 can rotate synchronously without twisting or jamming, thus ensuring that the pitch adjustment mechanism can work normally at any azimuth angle. This structure decouples the rotation action from the pitch action, allowing the nozzle to first adjust its orientation according to the left and right position of the arm, and then adjust the pitch angle according to the height and depth of the arm, ultimately making the air inlet accurately point to the air escape area around the arm.

[0047] Preferably, the front end of the negative pressure tube 17 can be provided with a funnel-shaped, duckbill-shaped, or elliptical flat-mouth suction port. The funnel-shaped suction port is suitable for expanding the close-range collection area, the duckbill-shaped suction port is suitable for forming a thin layer of suction flow close to the table surface, and the elliptical flat-mouth suction port is suitable for forming a strip-shaped collection area along the outside of the arm.

[0048] Furthermore, the inlet is made of a flexible, corrosion-resistant material, such as fluororubber or silicone rubber, and has multiple miniature shape-adjusting elements embedded circumferentially inside. By controlling the extension and retraction of the shape-adjusting elements at different positions, the inlet can be switched between the three aforementioned forms.

[0049] The shape adjustment element is preferably a miniature airbag segment or a shape memory alloy wire. When using miniature airbag segments, each segment is evenly distributed circumferentially around the inlet, and the local expansion or contraction of the inlet is achieved by independently controlling the inflation volume of each segment. When using shape memory alloy wire, each wire is woven or embedded circumferentially around the inlet, and its temperature is adjusted by controlling the current flowing through each wire, thereby controlling the amount of contraction and achieving precise control of the inlet shape. Regardless of the driving method used, the shape adjustment element is automatically controlled by the controller based on signals from the target detection sensor, ensuring that the inlet shape matches the current operating conditions.

[0050] In practical use, when the ultrasonic sensor 29 detects the operator's arm being inserted, the suction inlet of the middle zone nozzle automatically switches to an oval flat opening to perform a strip-like tracking and capture along the arm; when the temperature sensor 30 detects an increase in the upper temperature, the suction inlet of the upper zone nozzle automatically switches to a trumpet shape to expand the capture area for the rising hot airflow; when the concentration signal detected by the VOC sensor 31 exceeds the threshold and the temperature is normal, the suction inlet of the lower zone nozzle automatically switches to a duckbill shape and leans down close to the table surface to form a thin, ground-level suction flow.

[0051] The elliptical, flat-mouthed suction inlet forms a narrow negative pressure band along the arm's extension direction, achieving precise tracking and capture along the outer side of the arm with a relatively small suction volume, avoiding the problem of suction power dissipating in all directions with traditional circular inlets. The trumpet-shaped suction inlet increases the front-end capture area, adapting to the diffusion characteristics of rising hot airflow. The duckbill-shaped suction inlet forms a high-speed, thin-layer suction flow close to the table surface, forming a staged relay capture of descending gas in the vertical direction with the intercepting suction inlet 26. Thus, the tracking suction assembly 7 achieves two-dimensional adaptive adjustment from position to shape, optimizing capture efficiency under various operating conditions while reducing energy waste caused by ineffective suction.

[0052] A rubber protective sleeve 20 matching the negative pressure tube 17 is installed on the outer casing 12. The rubber protective sleeve 20 can be made of silicone rubber, fluororubber or solvent-resistant elastomer. It is used to cover the moving gap between the negative pressure tube 17 and the outer casing 12 to prevent corrosive vapors, droplets or dust from entering the drive mechanism, and at the same time to prevent the operator's hands from accidentally contacting the moving parts.

[0053] like Figures 3-4As shown, the interceptor suction port 26 is located on the operating surface of cabinet 1, inside the operating opening. The interceptor suction port 26 is a linear slit extending along the width of cabinet 1, its bottom connected to the third air supply pipe 28 via the second air supply pipe 27. A solenoid valve 2701 is installed on the second air supply pipe 27. The width of the linear slit can be 3mm to 20mm, and its length can cover the main area between the operator's arms, or it can be formed by multiple short slit segments arranged at intervals. The interceptor suction port 26 is located inside the operating opening rather than deep within cabinet 1 because when the operator's arms are inserted into the fume hood, a semi-enclosed pocket area is formed between the torso, arms, and the operating surface. This pocket area is located in front of the operator's chest and abdomen, close to the operating surface below and near the breathing zone above. Traditional rear exhaust airflow has difficulty penetrating this area, and the side nozzles are easily blocked by the arms. The interceptor suction port 26, located below this pocket area, can intercept the harmful gas at its source before it rises along the torso, guiding the pollutants into the second air supply pipe 27 and expelling them.

[0054] The mechanism of action of the interceptor suction port 26 differs from that of the side-tracking suction assembly 7. The tracking suction assembly 7 targets and captures localized escaping gases around the arm and near the operating vessel, while the interceptor suction port 26 intercepts the source of the pocket area dynamically formed after the operator's body intervenes. Combined, the area near the operating port on the cabinet 1 no longer relies solely on a single front-to-back airflow barrier, but instead forms multi-directional supplementary capture along the sides of the arm, above the arm, and under the tabletop. Especially when the operator's arms partially block the side-inhalation airflow, the interceptor suction port 26 can still create a downward or diagonally downward interception flow line between the arms, reducing the risk of contaminants rising along the chest and abdomen into the breathing zone.

[0055] Both air supply pipe 1 (24) and air supply pipe 2 (27) are connected to air supply pipe 3 (28), and the output end of air supply pipe 3 (28) is connected to exhaust fan 2. Solenoid valve 2 (25) is installed on air supply pipe 1 (24), and solenoid valve 3 (2701) is installed on air supply pipe 2 (27). Solenoid valve 2 (25) controls the on / off state of the branch containing the tracking suction assembly 7, and solenoid valve 3 (2701) controls the on / off state of the branch containing the intercepting suction port 26. Through the coordinated operation of solenoid valve 2 (25), solenoid valve 3 (2701), and solenoid valve 1 (10) on each auxiliary connecting pipe 9, the system can change the negative pressure distribution under different experimental conditions. For example, when the sensor only detects the operator approaching but does not detect a significant VOC signal, the tracking suction component 7 can be opened at a low degree to allow the nozzle to be positioned in advance and establish a weak trapping airflow; when the VOC concentration increases, the intercepting suction port 26 is opened and the opening of the lower exhaust zone 5 is increased to allow heavy or near-table-side escaping gases to be intercepted and discharged preferentially; when the temperature sensor 30 detects a significant hot airflow, the opening of the upper exhaust zone 4 is increased to prevent the hot plume from accumulating in the upper part of the cabinet 1 and escaping.

[0056] To convert sensor signals into suction nozzle actions and exhaust distribution actions, a controller is installed inside the cabinet 1 or in a control box outside the cabinet 1. The controller can be a microcontroller, PLC, or embedded control board. Its input terminals are electrically connected to the ultrasonic sensor 29, temperature sensor 30, and VOC sensor 31, and its output terminals are electrically connected to the stator 13, electric push rod 18, solenoid valve 10, solenoid valve 25, solenoid valve 2701, and exhaust port adjustment mechanism 6. The controller uses the distance signal from the ultrasonic sensor 29 to determine whether the operator is approaching, whether their arm is inside, and the approximate spatial position of the arm; it uses the signal from the temperature sensor 30 to determine whether there is rising hot airflow inside the cabinet; and it uses the signal from the VOC sensor 31 to determine whether there is organic vapor or other pollutants that require enhanced capture.

[0057] In use, the echo distance of the ultrasonic sensor 29 is first filtered, for example using moving average, median filtering, or Kalman filtering, to reduce momentary misjudgments caused by operator sleeve movements, glass door reflections, or laboratory glassware reflections. When the ultrasonic sensor 29 detects that the distance to the operator is less than a preset threshold, such as 300mm to 800mm, the controller determines that the operator is about to perform an operation and pre-drives the tracking suction assembly 7 to unfold. At this time, the stator 13 drives the rotor 14 to rotate the first negative pressure tube 15 to the corresponding azimuth angle, and the electric push rod 18 adjusts the pitch angle of the second negative pressure tube 17, so that the suction inlet of the multi-angle adjustable negative pressure nozzle 11 faces the position where the operator's arm is expected to enter. This pre-positioning action occurs before the operator's arm is fully inside the cabinet 1, so when the operator begins actual operation, the local capture airflow has already been established, avoiding the first escape of contaminants before they are captured.

[0058] When the VOC sensor 31 detects a signal exceeding a preset threshold, the controller controls the exhaust port adjustment mechanism 6 of the lower exhaust zone 5 to increase its opening, and simultaneously opens the solenoid valve 2701 on the gas supply pipe 27, enabling the interceptor suction port 26 to operate. The basis for this control logic is that the lower exhaust zone 5 has an independently adjustable exhaust port adjustment mechanism 6, and the interceptor suction port 26 has an independently controlled solenoid valve 2701. Both mechanisms work together to enhance the suction capacity near the work surface and inside the operating port area when VOC concentration increases. Since many organic solvent vapors are denser than air, their initial escape path often follows the work surface or slowly rises between the operator's arms. The increased opening of the lower exhaust zone 5, combined with the opening of the interceptor suction port 26, allows pollutants to be directly discharged in the early stages of diffusion, reducing their chance of entering the main operating space.

[0059] When the temperature sensor 30 detects that the temperature gradient or local temperature rise inside the cabinet exceeds a preset threshold, the controller controls the exhaust port adjustment mechanism 6 of the upper exhaust zone 4 to increase the opening. Hot airflow generated by heating plates, alcohol lamps, water baths, or reaction vessels tends to rise. If fixed downward or uniform exhaust is still used, the hot plume is easily concentrated at the top of the cabinet 1 or forced to roll back. In this embodiment, the temperature sensor 30 identifies the hot airflow and enhances its discharge through the upper exhaust zone 4, causing the hot plume to be drawn away along the guide ridge 3. If both the temperature sensor 30 and the VOC sensor 31 give a high response, the controller can maintain a certain opening in both the upper exhaust zone 4 and the lower exhaust zone 5, and dynamically allocate the exhaust volume according to the strength ratio of the two signals, thereby adapting to mixed conditions such as heating volatile solvents.

[0060] Preferably, the controller stores multiple operating modes, including normal mode, heating mode, heavy air mode, and mixed mode. In normal mode, the tracking suction component 7 operates at low power, and the exhaust port adjustment mechanism 6 maintains a basic opening. In heating mode, the opening of the upper exhaust zone 4 increases, and the suction nozzle faces upwards from the heat source or above the operator's arm. In heavy air mode, the opening of the lower exhaust zone 5 increases, the intercepting suction port 26 opens, and the suction nozzle faces the escaping area near the work surface. In mixed mode, the controller simultaneously adjusts the opening of the upper and lower exhaust zones according to the weights of the temperature signal and the VOC signal.

[0061] The working process of this invention can be understood as a continuous airflow relay path: when the operator approaches the operating port, the ultrasonic sensor 29 first detects the distance change, and the controller drives the multi-angle adjustable negative pressure nozzle 11 to adjust its azimuth and pitch angles accordingly. After the nozzle is adjusted to the correct position, it remains stationary, ensuring that the air intake is stably pointed towards the area around the arm where escaped gas may occur. Because the nozzle does not perform periodic sweeping, it causes minimal disturbance to the main airflow within the cabinet 1, thus maintaining the original airflow barrier from the outside to the inside at the operating port. During the experiment, if harmful gases are present near the arm, the tracking suction assembly 7 will draw away the gases through the negative pressure pipe 17, negative pressure pipe 15, auxiliary connecting pipe 9, main connecting pipe 8, rotary joint 23, and air supply pipe 24. If a pocket area is formed between the operator's arms, the intercepting suction port 26 will provide bottom interception airflow at the tabletop, and the pollutants in the area will be discharged through the air supply pipe 27. The remaining pollutants that move towards the rear of the cabinet 1 with the main airflow are divided into upper and lower paths at the guide ridge 3, and are discharged by the upper exhaust area 4 and the lower exhaust area 5 respectively.

[0062] Compared with the prior art, the present invention has at least the following beneficial effects: the operator's position is detected by ultrasonic sensor 29, hot airflow is detected by temperature sensor 30, and VOC emission is detected by VOC sensor 31; the nozzle orientation is achieved by stator 13 and rotor 14 driving negative pressure pipe 15, and nozzle pitch is achieved by ball groove 1501, ball 1701, and electric push rod 18; bottom interception is achieved by interception suction port 26, air supply pipe 27, and solenoid valve 2701; upper and lower exhaust distribution is achieved by guide ridge 3, upper exhaust zone 4, lower exhaust zone 5, and exhaust port adjustment mechanism 6. Therefore, the present invention can actively adapt to the dynamic emission path formed after the operator's arm intervention, improving local pollutant capture efficiency and reducing ineffective exhaust energy consumption while maintaining the stability of the airflow barrier at the cabinet opening.

[0063] After the operator's arm is inserted into the cabinet, a tracking suction assembly 7, a multi-angle adjustable negative pressure nozzle 11, an intercepting suction port 26, and an upper and lower partitioned exhaust structure are installed to address the vortex zone, rising diversion zone, sinking wall-attached zone, and dynamic pocket zone formed by the arm's turbulence. Using target detection sensors such as an ultrasonic sensor 29, the position of the operator's arm is sensed. The multi-angle adjustable negative pressure nozzle 11 can adjust the direction of the suction port and maintain static suction after adjustment, ensuring the nozzle is stably pointed towards the area around the arm where harmful gases are most likely to escape. This transforms the vortex dispersion zone, which is difficult to control after being disturbed by the arm in traditional fume hoods, into a localized area that can be directionally captured, reducing the risk of harmful gases rushing towards the operator's facial breathing area along the sides or back of the arm.

[0064] Meanwhile, this invention features an intercepting suction port 26 on the inner side of the operating surface near the operating opening. This port generates bottom-intercepting airflow within the semi-enclosed pocket area formed between the operator's arms, torso, and the operating surface. It draws in and intercepts polluting gases at the source before they rise along the operator's chest and abdomen, overcoming the limitations of traditional rear-wall exhaust and side-suction systems that struggle to reach this dynamic blind spot. This structure is particularly suitable for scenarios involving two-handed operation, prolonged arm obstruction of the main airflow, or diffusion of organic solvent vapors near the operating surface, significantly reducing the possibility of pollutants escaping from the front of the operating opening.

[0065] Furthermore, this invention divides the rear exhaust area of ​​the cabinet into an upper exhaust zone 4 and a lower exhaust zone 5 via a guide ridge 3, and adjusts the upper and lower exhaust volumes respectively via an exhaust port adjustment mechanism 6, allowing hot air, organic solvent heavy gases, and conventional pollutant gases to be received and discharged by the corresponding exhaust zones according to their movement trends. Combined with the detection signals from the temperature sensor 30 and the VOC sensor 31, the system can automatically adjust the nozzle orientation, the opening and closing of the interceptor nozzle, and the upper and lower exhaust ratio according to different experimental conditions such as heating, heavy gas, and mixing, thereby avoiding the problem of poor adaptability of fixed exhaust methods to different pollutant forms.

[0066] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0067] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A laboratory fume hood, comprising a cabinet body and an exhaust fan, characterized in that, Also includes: At least one set of tracking suction components is disposed on the side wall of the cabinet and near the operation port. The tracking suction components include a main connecting pipe, a secondary connecting pipe and a multi-angle adjustable negative pressure nozzle installed on the secondary connecting pipe. The multi-angle adjustable negative pressure nozzle can rotate independently in space around at least two non-parallel axes to change the direction of the inhalation port. At least one intercepting suction port is provided on the operating table of the cabinet. The intercepting suction port is located inside the operating port and is used to form a bottom intercepting airflow in the area between the operator's arms. Target detection sensors are used to sense the operator's position or arm movements; The multi-angle adjustable negative pressure nozzle and the interception suction port are connected to the exhaust fan through a pipeline. A controlled valve is installed on the pipeline. Both the controlled valve and the multi-angle adjustable negative pressure nozzle change their working state according to the signal from the target detection sensor.

2. The laboratory fume hood according to claim 1, characterized in that, The multi-angle adjustable negative pressure nozzle includes a housing, a stator, a rotor, and a negative pressure tube. The stator is fixed to the inner wall of the outer casing, the rotor is fixed to the negative pressure pipe, the negative pressure pipe is rotatably connected to the inside of the outer casing, and the stator drives the rotor to rotate, forcing the negative pressure pipe to rotate 360° around its own axis.

3. The laboratory fume hood according to claim 2, characterized in that, The multi-angle adjustable negative pressure nozzle also includes a second negative pressure tube. The front end of the first negative pressure tube is provided with a ball groove, and a ball that matches the ball groove is fixedly connected to the second negative pressure tube. The sphere and the spherical groove rotate together to form a kinematic pair that allows the second negative pressure pipe to pitch up and down relative to the first negative pressure pipe. The axis of the pitching motion is not parallel to the axis of the 360° rotation.

4. The laboratory fume hood according to claim 3, characterized in that, A slip ring is rotatably connected to the inner wall of the outer shell, and an electric push rod is hinged between the slip ring and the second negative pressure pipe. The electric push rod extends and retracts, driving the negative pressure tube to pitch around the center of the ball groove to cover different suction ranges.

5. The laboratory fume hood according to claim 1, characterized in that, A horizontally extending airflow guide ridge is provided on the rear wall of the cabinet opposite the operating port; an upper exhaust air area is formed above the airflow guide ridge, and a lower exhaust air area is formed below it. The openings of both the upper and lower exhaust zones are equipped with independent exhaust port adjustment mechanisms for dynamically distributing the upper and lower exhaust volumes.

6. The laboratory fume hood according to claim 5, characterized in that, The target detection sensor includes an ultrasonic sensor for detecting the operator's state; It also includes a temperature sensor and a VOC sensor installed inside the cabinet; When the VOC sensor detects a signal exceeding a threshold, the exhaust port adjustment mechanism in the lower exhaust zone increases its opening, and at the same time, the controlled valve of the intercepting suction port opens.

7. The laboratory fume hood according to claim 1, characterized in that, The interception suction port is a linear slit opened on the operating table, and its bottom is connected to the exhaust fan through the second air supply pipe. The second air supply pipe is equipped with a third solenoid valve.

8. The laboratory fume hood according to claim 1, characterized in that, The upper and lower ends of the main connecting pipe are rotatably connected to the cabinet through bearing two, and the lower end of the main connecting pipe is connected to the gas supply pipe one through a rotary joint.

9. The laboratory fume hood according to claim 1, characterized in that, The multi-angle adjustable negative pressure nozzle and the auxiliary connecting tube are detachably connected.

10. The laboratory fume hood according to claim 1, characterized in that, The secondary connecting pipes are distributed vertically along the main connecting pipe, and each secondary connecting pipe is equipped with a solenoid valve.

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