Biological safety cabinet

Abstract

The application belongs to the technical field of experimental equipment, and particularly relates to a biological safety cabinet. The application aims to solve the problem that the existing biological safety cabinet has unstable descending wind speed, which affects the normal work of the biological safety cabinet. The biological safety cabinet is provided with a first control valve at a top air inlet. When the working voltage of a blowing unit is greater than or equal to a preset first voltage threshold, the first control valve is configured to be opened to the maximum opening. By adjusting the working voltage of the blowing unit, the rotating speed of the blowing unit is adjusted. When the working voltage of the blowing unit is less than the first voltage threshold, the blowing unit is configured to operate according to the first voltage. By adjusting the opening and closing angle of the first control valve, the first wind speed of the biological safety cabinet is adjusted. The application combines the two ways of adjusting the blowing unit and adjusting the opening and closing angle of the first control valve to adjust the first wind speed of the biological safety cabinet, so that excessive noise of the biological safety cabinet is avoided.

Description

Technical Field

[0001] This application belongs to the field of experimental equipment technology, specifically relating to a biosafety cabinet. Background Technology

[0002] Biosafety cabinets are designed to protect the operator, the laboratory environment, and the experimental materials from exposure to infectious aerosols and splashes that may be generated during the handling of infectious experimental materials such as primary cultures, bacterial and viral strains, and diagnostic specimens.

[0003] Biosafety cabinets can be classified into three main categories: Class I, Class II, and Class III, to meet different biological research requirements. Among them, Class II biosafety cabinets are currently the most widely used type. In Class II biosafety cabinets, such as the B2 model, clean air is completely exhausted to the outside after passing through the work area. During this process, clean air is replenished into the biosafety cabinet through the air inlet. In related technologies, the air inlet of the biosafety cabinet is normally open, and the airflow is adjusted by controlling the speed of the supply fan, thereby controlling the downward airflow velocity in the work area. For AC fans, when the operating voltage is lower than the set value, the AC fan generates higher noise. Therefore, the supply fan of the biosafety cabinet is usually set with a minimum operating voltage to ensure that the noise of the supply fan meets the noise requirements of the biosafety cabinet.

[0004] However, this setup can easily lead to excessively high descent airflow, causing instability in the descent airflow and affecting the normal operation of the biosafety cabinet. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the existing technology, namely the problem of unstable descent air velocity in existing biosafety cabinets affecting the normal operation of biosafety cabinets.

[0006] This application provides a biosafety cabinet, comprising: a cabinet body; the cabinet body enclosing a working area with a front opening, the cabinet body having a bottom air inlet below the front side of the working area, and an air outlet at the top of the working area; a top air inlet and an air outlet at the top of the cabinet body; a first control valve installed at the top air inlet, the first control valve being configured to control the opening or closing of the top air inlet; a first wind speed sensor disposed within the working area, the first wind speed sensor being used to detect a first wind speed blowing from the air outlet towards the working area; a first air duct and a second air duct forming within the cabinet body, the two ends of the first air duct being connected to the bottom air inlet and the air outlet, respectively; The two ends of the second air duct are respectively connected to the top air inlet and the air outlet; an air supply unit is installed at the end of the second air duct near the air outlet, the air supply unit including an air supply fan; the air supply unit is configured to determine the operating voltage of the air supply unit according to the first wind speed when the operating voltage of the air supply unit is greater than or equal to a preset first voltage threshold, and the first control valve is configured to open to the maximum opening; when the operating voltage of the air supply unit is less than the first voltage threshold, the air supply unit is configured to operate according to the first voltage, and the first control valve is configured to determine the opening angle of the first control valve according to the first wind speed, wherein the first voltage is greater than or equal to the first voltage threshold.

[0007] In the above-mentioned optional technical solutions for biosafety cabinets, when the first wind speed is less than the preset first target wind speed, the opening and closing angle of the first control valve increases; when the first wind speed is greater than the first target wind speed, the opening and closing angle of the first control valve decreases.

[0008] In the optional technical solutions of the above-mentioned biosafety cabinet, when the first wind speed is less than the preset first target wind speed, the operating voltage of the air supply unit increases; when the first wind speed is greater than the first target wind speed, the operating voltage of the air supply unit decreases.

[0009] In the optional technical solution of the above-mentioned biosafety cabinet, the first control valve includes a valve plate and a linear actuator, both of which are located inside the cabinet body; one end of the valve plate is hinged to the cabinet body on the side of the top air inlet, and the other end of the valve plate is hinged to the output end of the linear actuator, which is fixed relative to the cabinet body; when the output end of the linear actuator extends, the valve plate is sealed to the top air inlet, thus closing the top air inlet; when the output end of the linear actuator retracts, the valve plate rotates relative to the top air inlet, thus opening the top air inlet; the linear actuator is configured to determine the extension length of the output end of the linear actuator based on the first wind speed, thereby determining the opening and closing angle of the first control valve.

[0010] In the above-mentioned optional technical solutions for biosafety cabinets, a first sealing ring is provided on the edge of the top air inlet, and the first sealing ring abuts and seals against the top surface of the valve plate; an annular mounting groove is provided on the bottom surface of the top air inlet, and a second sealing ring is provided in the mounting groove, and the second sealing ring abuts and seals against the circumferential side surface of the valve plate.

[0011] In the optional technical solution of the above-mentioned biosafety cabinet, a trigger switch is provided between the valve plate and the cabinet body where the top air inlet is located; the biosafety cabinet is equipped with an alarm device; when the linear actuator is configured to drive the valve plate to seal the connection with the top air inlet, the trigger switch sends a closing signal; when the linear actuator is configured to drive the valve plate to seal the connection with the top air inlet and the trigger switch does not send a closing signal, the alarm device sends an alarm signal.

[0012] In the optional technical solutions of the above-mentioned biosafety cabinet, an air inlet filter is provided on the top surface of the top air inlet.

[0013] In the optional technical solution of the above-mentioned biosafety cabinet, there are two air supply units, which are arranged at intervals along the length of the cabinet and symmetrically distributed at opposite ends of the top air inlet; there are two first wind speed sensors, which are respectively located at both ends of the length of the cabinet; the air supply unit is configured to determine the operating voltage based on the first wind speed detected by the first wind speed sensor at the same end when the operating voltage of the air supply unit is greater than or equal to the first voltage threshold.

[0014] In the optional technical solution of the above-mentioned biosafety cabinet, the air outlet is connected to an outdoor exhaust pipe, and a second control valve is installed in the outdoor exhaust pipe. The second control valve is configured to control the opening or closing of the outdoor exhaust pipe. An exhaust unit is installed at one end of the first air duct near the air outlet. The exhaust unit includes an exhaust fan. When the first control valve is configured to open, the second control valve is configured to open. The exhaust unit is configured to start so that the gas drawn in by the bottom air inlet is discharged through the first air duct, the air outlet, and the outdoor exhaust pipe. The air supply unit is configured to start so that the gas drawn in by the top air inlet is blown to the working area through the second air duct and the air supply outlet.

[0015] In the optional technical solution of the above-mentioned biosafety cabinet, the air outlet is provided with a second wind speed sensor, which is used to detect the second wind speed blown out of the air outlet; the exhaust unit is configured to determine the operating voltage of the exhaust unit according to the second wind speed when the operating voltage of the exhaust unit is greater than or equal to a preset second voltage threshold; the second control valve is configured to open to the maximum opening; when the operating voltage of the exhaust unit is less than the second voltage threshold, the exhaust unit is configured to operate according to the second voltage, and the second control valve is configured to determine the opening angle of the second control valve according to the second wind speed, wherein the second voltage is greater than or equal to the second voltage threshold.

[0016] In the optional technical solution of the above-mentioned biosafety cabinet, a connecting port is provided between the first air duct and the second air duct, and a third control valve is provided in the connecting port. The third control valve is configured to open or close the connecting port to connect or disconnect the first air duct and the second air duct. The air outlet is connected to an indoor air outlet pipe, and a fourth control valve is provided in the indoor air outlet pipe. When the first control valve is configured to be open, the third control valve is configured to be closed, and the fourth control valve is configured to be closed. When the first control valve is configured to be closed, the third control valve is configured to be open, the second control valve is configured to be closed, and the fourth control valve is configured to be open. The exhaust unit and the air supply unit are configured to be activated. Under the action of the exhaust unit and the air supply unit, part of the gas drawn in by the bottom air inlet is blown to the working area through the first air duct, the second air duct, and the air supply outlet, and the other part of the gas drawn in by the bottom air inlet is discharged through the first air duct, the air outlet, and the indoor air outlet pipe.

[0017] Those skilled in the art will understand that the biosafety cabinet in this embodiment of the application has a first control valve installed at the top air inlet. When the operating voltage of the air supply unit is greater than or equal to a preset first voltage threshold, the first control valve is configured to open to its maximum opening. By adjusting the operating voltage of the air supply unit, the rotation speed of the air supply unit is adjusted, thereby adjusting the first airflow speed of the biosafety cabinet, making the adjustment of the first airflow speed rapid and quick. When the operating voltage of the air supply unit is less than the first voltage threshold, the air supply unit is configured to operate according to the first voltage. By adjusting the opening and closing angle of the first control valve, the first airflow speed of the biosafety cabinet is adjusted. This allows for flexible adjustment of the first airflow speed and avoids excessive noise caused by excessively low operating voltage of the air supply unit. This embodiment of the application combines adjusting the air supply unit and adjusting the opening and closing angle of the first control valve to adjust the first airflow speed of the biosafety cabinet, ensuring that the first airflow speed meets the first target airflow speed and also avoiding excessive noise from the biosafety cabinet, thus meeting the noise requirements of the biosafety cabinet. Attached Figure Description

[0018] The following description, with reference to the accompanying drawings, outlines alternative embodiments of the biosafety cabinet of this application. The drawings are as follows:

[0019] Figure 1 This is a schematic diagram of the principle structure of the biosafety cabinet provided in the embodiments of this application;

[0020] Figure 2 This is a schematic diagram of the structure of the biosafety cabinet provided in the embodiments of this application;

[0021] Figure 3 This is a schematic diagram of the gas flow direction in mode B2 of the biosafety cabinet provided in this application embodiment;

[0022] Figure 4 This is an explosion diagram of the biosafety cabinet provided in the embodiments of this application;

[0023] Figure 5 This is a side view of the biosafety cabinet provided in an embodiment of this application;

[0024] Figure 6 yes Figure 5 Sectional view of AA;

[0025] Figure 7 yes Figure 6 Enlarged schematic diagram of region P in the middle;

[0026] Figure 8 This is a schematic diagram of the gas flow direction in mode A2 of the biosafety cabinet provided in this application embodiment;

[0027] Figure 9 This is a schematic diagram of the gas flow direction in the A2 exhaust mode of the biosafety cabinet provided in this application embodiment;

[0028] Figure 10 This is a schematic diagram of the exhaust connector of the biosafety cabinet provided in the embodiments of this application.

[0029] In the attached diagram: 100: Cabinet; 101: Working area; 102: Bottom air inlet; 103: Air outlet; 104: Top air inlet; 1041: Air inlet filter; 1042: Mounting recess; 105: Air outlet; 110: First air duct; 111: Exhaust unit; 112: Exhaust filter; 113: Bottom air duct; 114: Rear air duct; 120: Second air duct; 121: Air supply unit; 122: Air supply filter; 130: Outer shell; 131: Outer side panel; 132: Bottom plate; 133: Top plate; 134: Front cover; 135: Glass door; 136: Drain tray; 140: Workbench; 150: Inner side panel; 160: Partition; 161: Connecting port; 210: Third control valve connecting port; 220: First control valve top air inlet; 221: Valve plate; 222: Linear actuator; 223: First sealing ring; 224: Second sealing ring; 230: Second control valve outdoor exhaust pipe; 240: Fourth control valve indoor exhaust pipe; 300: Outdoor exhaust pipe; 310: Outdoor exhaust fan; 400: Indoor exhaust pipe; 500: Exhaust connector; 501: First interface; 502: Second interface; 503: Third interface; 510: Exhaust hood; 520: Pipe body; 600: Support leg. Detailed Implementation

[0030] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0031] Secondly, it should be noted that in the description of the embodiments of this application, the terms "inner" and "outer" and other terms indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of this application.

[0032] Furthermore, it should be noted that, in the description of the embodiments of this application, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0033] Biosafety cabinets are designed to protect the operator, the laboratory environment, and the experimental materials from exposure to infectious aerosols and splashes that may be generated during the handling of infectious experimental materials such as primary cultures, bacterial and viral strains, and diagnostic specimens.

[0034] Biosafety cabinets can be divided into three main categories: Class I, Class II, and Class III, to meet different biological research requirements. Among them, Class II biosafety cabinets are currently the most widely used type. In Class II biosafety cabinets, the clean air is completely exhausted to the outside after passing through the work area. During this process, clean air is replenished into the biosafety cabinet through the air inlet. In related technologies, the air inlet of the biosafety cabinet is normally open. By controlling the speed of the supply fan, the air volume at the air inlet is adjusted, thereby controlling the downward air velocity in the work area. For AC fans, when the operating voltage is lower than the set value, the AC fan generates high noise. Therefore, the supply fan of the biosafety cabinet is usually set with a minimum operating voltage to ensure that the noise of the supply fan meets the noise requirements of the biosafety cabinet. However, this setting can easily lead to excessively high downward air velocity, resulting in unstable downward air velocity and affecting the normal operation of the biosafety cabinet.

[0035] In view of this, this application provides a biosafety cabinet with a first control valve at the top air inlet. When the operating voltage of the air supply unit is greater than or equal to a preset first voltage threshold, the air supply unit determines the operating voltage based on the first wind speed in the working area. At this time, the first control valve is configured to open to its maximum opening. When the operating voltage of the air supply unit is less than the first voltage threshold, the air supply unit is configured to operate according to the first voltage, and the third control valve is configured to determine the opening and closing angle of the first control valve based on the first wind speed. This configuration can ensure the stability of the first wind speed in the working area, avoid the first wind speed being too high or too low, meet the descent wind speed standard of the biosafety cabinet, and also avoid excessive noise caused by the air supply unit operating voltage being too low.

[0036] The optional technical solutions for the biosafety cabinets in the embodiments of this application are described below with reference to the accompanying drawings.

[0037] First, it should be noted that in this embodiment, the orientation is determined based on the installation location of the biosafety cabinet. The directional term "front" refers to the side of the biosafety cabinet with the front window, where the operator performs experiments on the workbench; the directional terms "back" and "behind" indicate the side away from the front window; the directional term "top" indicates the side away from the ground; and the directional term "bottom" indicates the side facing the ground. The Z-axis indicates the vertical direction.

[0038] Figure 1 This is a schematic diagram of the principle structure of the biosafety cabinet provided in the embodiments of this application.

[0039] Reference Figure 1 The biosafety cabinet of this application embodiment includes a cabinet body 100 and support legs 600. An air duct is formed inside the cabinet body 100 to guide gas to the work area 101 or exhaust it to the outside of the cabinet body 100. The support legs 600 are used to support the cabinet body 100. Four support legs 600 can be provided and fixed to the four top corners of the bottom of the cabinet body 100 respectively. The bottom end of the support legs 600 can also be provided with casters to facilitate the movement of the biosafety cabinet.

[0040] In this embodiment, the cabinet 100 encloses a working area 101 with a front opening. The front opening of the cabinet 100 serves as the front window of the biosafety cabinet, through which the operator operates within the working area 101. A bottom air inlet 101 is provided below the front of the working area 101 for drawing in gas. An air outlet 103 is provided at the top of the working area 101 for supplying gas into the working area 101. The top of the cabinet 100 also has a top air inlet 104 and an air outlet 105; the top air inlet 104 draws in indoor gas, and the air outlet 105 exhausts gas.

[0041] A first wind speed sensor is installed in the working area to detect the first wind speed blowing from the air outlet 103 into the working area. Since the air from the air outlet 103 blows downwards into the working area, the first wind speed is also referred to as the "descending wind speed".

[0042] The cabinet 100 forms a first air duct 110 and a second air duct 120. The two ends of the first air duct 110 are connected to the bottom air inlet 102 and the air outlet 105, respectively. In this way, the gas in the working area 101 enters the first air duct 110 through the bottom air inlet 102 and is discharged through the air outlet 105. The two ends of the second air duct 120 are connected to the top air inlet 104 and the air outlet 103, respectively. In this way, the gas drawn in by the top air inlet 104 enters the second air duct 120 and is sent into the working area 101 through the air outlet 103.

[0043] The top air inlet 104 is equipped with a first control valve 220, which is configured to control the opening or closing of the top air inlet 104. When the first control valve 220 is open, the top air inlet 104 is open, and indoor air can enter the second air duct 120 through the top air inlet 104. When the first control valve 220 is closed, the top air inlet 104 is closed.

[0044] Figure 2 This is a structural schematic diagram of the biosafety cabinet provided in an embodiment of this application. (Combined with...) Figure 2An air inlet filter 1041 is provided on the top surface of the top air inlet 104 to filter the gas entering the second air duct 120 from the top air inlet 104. For example, the air inlet filter 1041 can be a pre-filter.

[0045] Combined again Figure 1 An air supply unit 121 is installed at one end of the second air duct 120 near the air outlet 103. The air supply unit 121 provides power for the gas to enter the working area 101 through the air outlet 103. An air supply filter 122 is installed between the air supply unit 121 and the air outlet 103 to filter the gas entering the working area 101. The air supply unit 121 is configured to be activated when the biosafety cabinet is in use. The air supply unit 121 is activated during the use of the biosafety cabinet, that is, the air supply unit 121 is activated in all modes of the biosafety cabinet.

[0046] When the operating voltage of the air supply unit 121 is greater than or equal to a preset first voltage threshold, the air supply unit 121 is configured to determine its operating voltage based on a first air velocity. At this time, the first control valve 220 is configured to open to its maximum opening. This can be understood as follows: when the operating voltage of the air supply unit 121 is greater than or equal to the preset first voltage threshold, the first control valve 220 opens to its maximum opening, and the air supply unit 121 dynamically adjusts its operating voltage according to the first air velocity, thereby adjusting the rotational speed of the air supply unit 121, and consequently adjusting the first air velocity of the biosafety cabinet to ensure that the first air velocity of the biosafety cabinet meets the standard. It should be noted that the maximum opening of the first control valve 220 is a pre-set, relatively large opening angle.

[0047] In this embodiment, the operating voltage of the air supply unit 121 is negatively correlated with the first wind speed. When the first wind speed is less than a preset first target wind speed, the air supply unit 121 increases its operating voltage, thereby increasing its rotational speed; when the first wind speed is greater than the first target wind speed, the air supply unit 121 decreases its operating voltage, thereby decreasing its rotational speed. Of course, when the first wind speed is equal to the first target wind speed, the air supply unit 121 maintains its operating voltage, thereby ensuring that the first wind speed is equal to the first target wind speed.

[0048] When the operating voltage of the air supply unit 121 is less than the first voltage threshold, further reducing the operating voltage would cause it to generate excessive noise, failing to meet the noise requirements of the biosafety cabinet. Therefore, the air supply unit 121 is configured to operate at a first voltage, which is greater than or equal to the first voltage threshold. In other words, the air supply unit 121 maintains operation at the first voltage. At this time, the first control valve 220 is configured to determine its opening angle based on the first airflow velocity. This can be understood as follows: when the operating voltage of the air supply unit 121 is less than the first voltage threshold, the air supply unit 121 maintains a constant operating voltage, and the first airflow velocity of the biosafety cabinet is controlled by adjusting the opening angle of the first control valve 220.

[0049] The air supply unit 121 in this embodiment includes an air supply fan and a voltage regulating element. The voltage regulating element is electrically connected to the air supply fan and can regulate the operating voltage of the air supply fan, thereby adjusting the operating voltage of the air supply unit 121. The voltage regulating element can be a silicon controlled rectifier (SCR), which controls the voltage of the air supply fan by controlling the current; the voltage regulating element can also be a transformer, etc.

[0050] In this embodiment, the opening angle of the first control valve 220 is negatively correlated with the first wind speed. When the first wind speed is less than a preset first target wind speed, the opening angle of the first control valve 220 increases, thereby increasing the first wind speed; when the first wind speed is greater than the first target wind speed, the opening angle of the first control valve 220 decreases, thereby increasing the first wind speed. Of course, when the first wind speed equals the first target wind speed, the current opening angle of the third control valve 210 is maintained, thereby ensuring that the first wind speed equals the first target wind speed.

[0051] During the aforementioned adjustment of the first airflow rate, the first control valve 220 is configured to open the top air inlet 104, and the gas drawn in through the bottom air inlet 102 is discharged through the first air duct 110 and the air outlet 105; the air supply unit 121 is configured to start, and the gas drawn in through the top air inlet 104 is blown towards the working area 101 through the second air duct 120 and the air outlet 103. In this mode, all gas inside the biosafety cabinet is discharged, making it suitable for microbial experiments involving volatile toxic chemicals and radioactive elements as auxiliary agents.

[0052] In some possible implementations, two air supply units 121 are provided, arranged at intervals along the length of the cabinet 100. This arrangement of two air supply units 121 not only increases the power of airflow delivery but also helps to further improve the uniformity of airflow delivered downward to the working area 101. The two air supply units 121 are symmetrically distributed at opposite ends of the top air inlet 104, which further improves the uniformity of airflow.

[0053] Two first wind speed sensors are provided, and the two first wind speed sensors are respectively located at both ends of the cabinet 100 along its length; for example, a first wind speed sensor is set at the left end of the working area 101, and a first wind speed sensor is set at the right end of the working area 101. In this case, the air supply unit 121 on the left corresponds to the first wind speed sensor on the left, and the air supply unit 121 on the right corresponds to the first wind speed sensor on the right.

[0054] When the operating voltage of the air supply unit 121 is greater than or equal to the first voltage threshold, the air supply unit 121 is configured to determine its operating voltage based on the first wind speed detected by the first wind speed sensor at the same end. This can be understood as each air supply unit 121 operating independently. This configuration improves both the uniformity of airflow and the reliability of the biosafety cabinet; if one air supply unit 121 fails, the other air supply unit 121 can still operate. At this time, both third control valves 210 are opened to their maximum opening.

[0055] Therefore, in this embodiment of the biosafety cabinet, when the operating voltage of the air supply unit 121 is greater than or equal to a preset first voltage threshold, the first control valve 220 is configured to open to its maximum opening. By adjusting the operating voltage of the air supply unit 121, the rotation speed of the air supply unit 121 is adjusted, thereby adjusting the first airflow speed of the biosafety cabinet, making the adjustment of the first airflow speed rapid and quick. When the operating voltage of the air supply unit 121 is less than the first voltage threshold, the air supply unit 121 is configured to operate according to the first voltage. By adjusting the opening angle of the first control valve 220, the first airflow speed of the biosafety cabinet is adjusted. This allows for flexible adjustment of the first airflow speed and avoids excessive noise caused by an excessively low operating voltage of the air supply unit 121. This embodiment of the application combines adjusting the air supply unit 121 and adjusting the opening angle of the first control valve 220 to adjust the first airflow speed of the biosafety cabinet, ensuring that the first airflow speed meets the first target airflow speed and avoiding excessive noise from the biosafety cabinet, thus meeting the noise requirements of the biosafety cabinet.

[0056] The biosafety cabinet in this embodiment can be a B2 type biosafety cabinet. Therefore, an outdoor exhaust duct 300 is connected to the air outlet 105 to lead the gas discharged from the air outlet 105 to the outside. A second control valve 230 is installed inside the outdoor exhaust duct 300. The second control valve 230 is configured to control the opening or closing of the outdoor exhaust duct 300. When the second control valve 230 is open, the outdoor exhaust duct 300 is open; when the second control valve 230 is closed, the outdoor exhaust duct 300 is closed.

[0057] To power the exhaust air from the outlet 105, an exhaust unit 111 is installed at one end of the first air duct 110 near the outlet 105, thereby providing power for gas exhaust. An exhaust filter 112 is installed between the exhaust unit 111 and the outlet 105 to filter the exhaust gas. The exhaust unit 111 is configured to be activated when the biosafety cabinet is in use; that is, the exhaust unit 111 is activated in all modes of the biosafety cabinet.

[0058] Figure 3 This is a schematic diagram of the gas flow in mode B2 of the biosafety cabinet provided in this application embodiment. In the attached figure, arrow a (empty) represents clean gas; arrow b (filled) represents contaminated gas. (Combined with...) Figure 3 When the biosafety cabinet is in B2 mode, the first control valve 220 and the second control valve 230 are both configured to open; the exhaust unit 111 is activated to allow gas drawn in through the bottom air inlet 102 to be exhausted through the first air duct 110, the air outlet 105, and the outdoor exhaust pipe 300; the air supply unit 121 is activated to allow gas drawn in through the top air inlet 104 to be blown towards the work area 101 through the second air duct 120 and the air supply outlet 103. This mode of the biosafety cabinet can be used in microbial experiments where volatile toxic chemicals and radioactive elements are used as auxiliary agents.

[0059] In this embodiment of the application, a second wind speed sensor is provided at the air outlet 105. The second wind speed sensor is used to detect the second wind speed blown out of the air outlet 105.

[0060] When the operating voltage of the exhaust unit 111 is greater than or equal to a preset second voltage threshold, the exhaust unit 111 is configured to determine its operating voltage based on the second wind speed, and the second control valve 230 is configured to open to its maximum opening. This can be understood as follows: when the operating voltage of the exhaust unit 111 is greater than or equal to the second voltage threshold, the second control valve 230 opens to its maximum opening, and the second wind speed is adjusted by regulating the operating voltage of the exhaust unit 111, making the adjustment of the second wind speed rapid and quick.

[0061] In this embodiment, the operating voltage of the exhaust unit 111 is negatively correlated with the second wind speed. When the second wind speed is less than the preset second target wind speed, the exhaust unit 111 increases its operating voltage, thereby increasing its rotational speed; when the second wind speed is greater than the second target wind speed, the exhaust unit 111 decreases its operating voltage, thereby decreasing its rotational speed. Of course, when the second wind speed is equal to the second target wind speed, the exhaust unit 111 maintains its operating voltage, thereby ensuring that the second wind speed is equal to the second target wind speed.

[0062] When the operating voltage of the exhaust unit 111 is less than the second voltage threshold, the exhaust unit 111 is configured to operate according to the second voltage. When the second voltage is greater than or equal to the second voltage threshold, the second control valve 230 is configured to determine its opening angle based on the second airflow rate. This can be understood as follows: when the operating voltage of the exhaust unit 111 is less than the second voltage threshold, the exhaust unit 111 maintains a constant operating voltage. By adjusting the opening angle of the second control valve 230, the second airflow rate of the biosafety cabinet is controlled. This allows for flexible adjustment of the second airflow rate and avoids excessive noise caused by excessively low operating voltage of the exhaust unit 111.

[0063] The exhaust unit 111 of this embodiment includes a supply fan and a voltage regulating element. The voltage regulating element is electrically connected to the supply fan and can regulate the operating voltage of the exhaust fan, thereby adjusting the operating voltage of the exhaust unit 111. The voltage regulating element can be a silicon controlled rectifier (SCR), which controls the voltage of the supply fan by controlling the current; the voltage regulating element can also be a transformer, etc.

[0064] In this embodiment, the opening / closing angle of the second control valve 230 and the second wind speed are negatively correlated. When the second wind speed is less than the preset second target wind speed, the opening / closing angle of the second control valve 230 increases, thereby increasing the second wind speed; when the second wind speed is greater than the second target wind speed, the opening / closing angle of the second control valve 230 decreases, thereby increasing the second wind speed. Of course, when the second wind speed is equal to the second target wind speed, the current opening / closing angle of the second control valve 230 is maintained, thereby ensuring that the second wind speed is equal to the second target wind speed.

[0065] Therefore, the biosafety cabinet in this embodiment of the application adopts a combination of adjusting the exhaust unit 111 and adjusting the opening and closing angle of the control valve to adjust the second air speed of the biosafety cabinet, ensuring that all the gas in the biosafety cabinet is discharged, and also avoiding excessive noise from the biosafety cabinet, thus meeting the noise requirements of the biosafety cabinet.

[0066] To provide power for gas exhaust, an exhaust fan 310 is installed inside the outdoor exhaust duct 300. When the second control valve 230 is configured to open, the exhaust fan 310 is configured to start to improve exhaust efficiency and prevent outdoor air backflow into the biosafety cabinet. In the first mode, the exhaust fan 310 is configured to be off. Typically, the exhaust fan 310 is a laboratory fan, and adjusting the second airflow speed using the exhaust unit 111 is more convenient.

[0067] The following reference Figures 4 to 7 The structure and function of the first control valve 220 in this embodiment are described. Wherein, Figure 4 This is an explosion diagram of the biosafety cabinet provided in the embodiments of this application; Figure 5This is a side view of the biosafety cabinet provided in an embodiment of this application; Figure 6 yes Figure 5 Sectional view of AA; Figure 7 yes Figure 6 A magnified schematic diagram of region P in the middle.

[0068] like Figure 4 As shown, the first control valve 220 in this embodiment includes a valve plate 221 and a linear actuator 222, both of which are located inside the cabinet 100.

[0069] One end of the valve plate 221 is hinged to the cabinet 100 on the side of the top air inlet 104, and the other end of the valve plate 221 is hinged to the output end of the linear actuator 222. For example, the rear end of the valve plate 221 is hinged to the cabinet 100 on the side of the top air inlet 104. In this embodiment, the rear end of the valve plate 221 is hinged to the front side of the exhaust unit 111 housing; the bottom surface of the front end of the valve plate 221 is hinged to the output end of the linear actuator 222.

[0070] In this embodiment of the application, the linear driver 222 is fixed relative to the cabinet 100. For example, the side of the linear driver 222 away from its output end is fixed to the cabinet 100, so that the output end of the linear driver 222 can extend or retract relative to the cabinet 100.

[0071] The linear actuator 222 in this embodiment can extend or retract linearly, and can be a linear motor driver, a cylinder, a hydraulic cylinder, etc. When the output end of the linear actuator 222 extends, the valve plate 221 is sealed to the top air inlet 104, thus closing the top air inlet 104; when the output end of the linear actuator 222 retracts, the valve plate 221 rotates relative to the top air inlet 104, thus opening the top air inlet 104. The linear actuator 222 in this embodiment is configured to determine the extension length of the output end of the linear actuator 222 based on a first wind speed, thereby determining the opening and closing angle of the first control valve 220, and thus adjusting the first wind speed.

[0072] When the first wind speed is less than the preset first target wind speed, the extension length of the output end of the linear actuator 222 decreases, thereby increasing the opening and closing angle of the first control valve 220, thus increasing the first wind speed. When the first wind speed is greater than the first target wind speed, the extension length of the output end of the linear actuator 222 increases, and the opening and closing angle of the first control valve 220 decreases, thereby increasing the first wind speed. Of course, when the first wind speed is equal to the first target wind speed, the extension length of the output end of the linear actuator 222 is maintained, thereby maintaining the current opening and closing angle of the third control valve 210, thus ensuring that the first wind speed is equal to the first target wind speed.

[0073] In some possible implementations, multiple linear actuators 222 are provided, such as two. The multiple linear actuators 222 are arranged at intervals along the length direction of the valve plate 221 (corresponding to the X-axis direction in the figure). This arrangement helps to improve the driving force of the valve plate 221 and ensures that the valve plate 221 opens and closes smoothly. It can also improve the reliability of the first control valve 220. If one of the linear actuators 222 fails, the other linear actuators 222 can still drive the valve plate 221 to move.

[0074] Combination Figures 5 to 7 A first sealing ring 223 is provided on the edge of the top air inlet 104, and the first sealing ring 223 abuts against the top surface of the valve plate 221 for sealing. For example, the first sealing ring 223 has a side sealing strip, which provides a stable and reliable seal.

[0075] The bottom surface of the top air inlet 104 is provided with an annular mounting groove 1042, and a second sealing ring 224 is provided in the mounting groove 1042. The second sealing ring 224 abuts and seals against the circumferential side of the valve plate 221. The second sealing ring 224 can be an inflatable sealing ring. By inflating the inflatable sealing ring with air, it expands and achieves abutment and seal against the top surface of the valve plate 221.

[0076] In this embodiment, by setting a first sealing ring 233 and a second sealing ring 224, the edges of the valve plate 221 and the top air inlet 104 are doubly sealed, ensuring stable and reliable sealing and preventing air leakage when the first control valve 220 is closed.

[0077] In some possible implementations, a trigger switch is provided between the valve plate 221 and the cabinet 100 with the top air inlet 104. The trigger switch can be a magnetic switch, a limit switch, etc. The biosafety cabinet is equipped with an alarm device, which includes, but is not limited to, an audible alarm, a light alarm, and a display. The display issues an alarm signal by showing an alarm symbol.

[0078] When the linear actuator 222 is configured to drive the valve plate 221 into a sealed connection with the top air inlet 104, the trigger switch sends a closing signal, indicating that the valve plate 221 is closing the top air inlet 104. When the linear actuator 222 is configured to drive the valve plate 221 into a sealed connection with the top air inlet 104, and the trigger switch does not send a closing signal, it indicates that the first control valve 220 has malfunctioned, causing the valve plate 221 to fail to effectively close the top air inlet 104, and the alarm device sends an alarm signal.

[0079] This application embodiment improves the stability and reliability of the first control valve 220's closing operation by setting a trigger switch and an alarm device, thus avoiding air leakage at the top air inlet 104.

[0080] In some possible implementations, a pressure sensor is provided at the edge of the air inlet port of the air supply unit 121 to determine whether the air supply unit 121 is operating normally. When the air supply unit 121 is operating normally, the pressure sensor detects a negative pressure. When the air supply unit 121 is open but the first control valve 220 is not open, if the negative pressure detected by the pressure sensor is greater than or equal to a preset pressure, such as 100 Pa, the first control valve 220 is abnormal, and the alarm device issues an alarm signal. When the air supply unit 121 is open and the first control valve 220 is open, the negative pressure detected by the pressure sensor is less than or equal to the preset pressure, indicating that both the first control valve 220 and the air supply unit 121 are operating normally.

[0081] Figure 8 This is a schematic diagram of the gas flow direction in mode A2 of the biosafety cabinet provided in this application embodiment; Figure 9 This is a schematic diagram of the gas flow direction in the A2 exhaust mode of the biosafety cabinet provided in this application embodiment. In the figure, arrow a (without filling) represents clean gas; arrow b (with filling) represents contaminated gas.

[0082] The biosafety cabinet in this application embodiment not only has the aforementioned B2 mode, but also has an A2 mode and an A2 exhaust mode. The following describes its features in conjunction with... Figure 8 and Figure 9 The airflow direction of the biosafety cabinet in the A2 mode and the A2 exhaust mode of the embodiments of this application are described respectively.

[0083] like Figure 8 As shown, in this embodiment of the application, a connecting port 161 is provided between the second air duct 120 and the first air duct 110, allowing the second air duct 120 and the first air duct 110 to be connected through the connecting port 161. A third control valve 210 is installed in the connecting port 161. The third control valve 210 is configured to open or close, thereby connecting or isolating the first air duct 110 and the second air duct 120. When the third control valve 210 is configured to open, the first air duct 110 and the second air duct 120 are connected, and air in the second air duct 120 can enter the first air duct 110 and be delivered to the working area 101 via the air outlet 103; when the third control valve 210 is configured to close, the first air duct 110 and the second air duct 120 are isolated.

[0084] The air outlet 105 is connected to an indoor exhaust pipe 400, which is used to draw the gas discharged from the air outlet 105 into the room. Figure 10 This is a structural schematic diagram of the exhaust connector of the biosafety cabinet provided in an embodiment of this application. (Combined with...) Figure 2 , Figure 8 as well as Figure 10The biosafety cabinet in this embodiment of the application also includes an exhaust connector 500, which provides a connection structure for the indoor exhaust duct 400 and the outdoor exhaust duct 300. The exhaust connector 500 in this embodiment of the application has a first interface 501, a second interface 502 and a third interface 503. The first interface 501 is connected to the air outlet 105, the second interface 502 is connected to the outdoor exhaust duct 300, and the third interface 503 is connected to the indoor exhaust duct 400.

[0085] The exhaust connector 500 of this application embodiment includes an exhaust hood 510 and a pipe body 520. The exhaust hood 510 can be a rectangular cover with an opening at the bottom, and the bottom opening is a first interface 501. The exhaust hood 510 is sealed and installed on the top plate 133 of the cabinet 100. The bottom end of the pipe body 520 is fixed to the top of the exhaust hood 510. The top of the pipe body 520 forms a second interface 502 and a third interface 503 respectively. The opening direction of the second interface 502 is vertical, which facilitates the connection of the outdoor exhaust pipe 300. The opening direction of the third interface 503 is perpendicular to the opening direction of the second interface 502, which facilitates the connection and arrangement of the pipe.

[0086] In order to achieve on / off control of the indoor exhaust duct 400, combined with Figure 3 and Figure 4 A fourth control valve 240 is installed inside the indoor exhaust duct 400. The fourth control valve 240 is configured to control the opening or closing of the indoor exhaust duct 400. When the fourth control valve 240 is configured to be open, the indoor exhaust duct 400 is configured to be open; when the fourth control valve 240 is configured to be closed, the indoor exhaust duct 400 is configured to be closed.

[0087] When the first control valve 220 is configured to open, that is, when the biosafety cabinet is in B2 mode, the third control valve 210 is configured to close and the fourth control valve 240 is configured to close.

[0088] When the first control valve 220 is configured to be closed, the third control valve 210 is configured to be opened to connect the first air duct 110 and the second air duct 120; the second control valve 230 is configured to be closed, and the outdoor exhaust duct 300 is closed; the fourth control valve 240 is configured to be opened, and the indoor exhaust duct 400 is opened; the exhaust unit 111 and the air supply unit 121 are configured to be activated.

[0089] Combination Figure 8Under the action of the exhaust unit 111 and the supply unit 121, part of the gas drawn in through the bottom air inlet 102 enters the second air duct 120 through the first air duct 110 and the connecting port 161. The gas in the second air duct 120 is then blown towards the work area 101 through the supply port 103. The remaining part of the gas drawn in through the bottom air inlet 102 is discharged through the first air duct 110, the air outlet 105, and the indoor exhaust pipe 400. At this time, the biosafety cabinet operates in A2 mode, which can be used for standard microbiological experiments, etc. Optionally, 30% of the gas in the work area 101 is discharged through the indoor exhaust pipe 400, and 70% of the gas re-enters the work area 101 through the first air duct 110, the connecting port 161, the second air duct 120, and the supply port 103.

[0090] Combination Figure 9 When the biosafety cabinet is in A2 exhaust mode, when the first control valve 220 is configured to be closed, the third control valve 210 is configured to be opened to connect the first air duct 110 and the second air duct 120; the second control valve 230 is configured to be opened, and the outdoor exhaust pipe 300 is opened; the fourth control valve 240 is configured to be closed, and the indoor exhaust pipe 400 is closed; the exhaust unit 111, the air supply unit 121 and the exhaust fan 310 are all configured to be started.

[0091] Part of the air drawn in through the bottom air inlet 102 enters the second air duct 120 via the first air duct 110 and the connecting port 161. The air in the second air duct 120 is then blown towards the working area 101 through the air outlet 103. The remaining part of the air drawn in through the bottom air inlet 102 is discharged through the first air duct 110, the air outlet 105, and the outdoor exhaust pipe 300. Compared to mode B2, mode A2 with external exhaust has lower power consumption and is more energy-efficient.

[0092] The difference between A2 mode and A2 exhaust mode is that in the first mode, the gas in the outlet 105 is discharged into the room through the indoor exhaust pipe 400. The first mode can be applied to standard microbiological experiments, etc. In the second mode, the gas in the outlet 105 is discharged to the outside through the outdoor exhaust pipe 300. The second mode can be applied to microbiological experiments in which trace amounts of volatile toxic chemicals and trace amounts of radioactive elements are used as auxiliary agents.

[0093] Therefore, in this embodiment, the biosafety cabinet can operate in three modes, and the on / off states of the control valves and motors are detailed in Table 1:

[0094] Table 1

[0095] model Valve 1 Valve 2 Valve Three Valve 4 air supply unit Exhaust unit External exhaust fan A2 mode close close open open run run closure A2 External Discharge Mode close open open close run run run B2 mode open open close close run run run

[0096] It should be noted that A2 mode refers to the working mode of the A2 type biosafety cabinet, A2 exhaust mode refers to the working mode of the A2 exhaust type biosafety cabinet, and B2 mode refers to the working mode of the B2 type.

[0097] Therefore, the biosafety cabinet in this embodiment controls the direction of gas flow in the air duct by controlling four electrically controlled valves and three fans, so that the biosafety cabinet can be formed in different types to suit different experimental requirements, thereby improving the application range of the biosafety cabinet; the laboratory does not need to be equipped with two devices, which helps to reduce the installation space occupied and reduce costs.

[0098] The following is combined Figure 1 , Figure 2 , Figure 4 , Figure 5 as well as Figure 6 The structure of the cabinet in the embodiments of this application is described.

[0099] In some possible implementations, the first air duct 110 includes a connected bottom air duct 113 and a rear air duct 114. The bottom air duct 113 is located at the bottom of the working area 101, and the rear air duct 114 is located at the back of the working area 101. The front end of the bottom air duct 113 is connected to the bottom air inlet 102, and the rear air duct 114 is connected to the air outlet 105, thereby guiding the air entering from the front to the top. The second air duct 120 is located at the top of the working area 101, and the second air duct 120 is located in front of the rear air duct 114, facilitating the formation of a downward airflow that blows towards the working area 101. Through the above arrangement, the first air duct 110 and the second air duct 120 within the cabinet 100 have a compact structure.

[0100] The cabinet 100 in this embodiment includes: an outer shell 130, a workbench 140, an inner side panel 150, and a partition 160.

[0101] The outer casing 130 includes an outer side panel 131 with a front opening, a bottom plate 132, a top plate 133, and a front cover 134. The outer side panel 131 includes a back side plate and two side plates disposed on both sides of the back side plate. The bottom plate 132 and the top plate 133 are respectively fixed to the bottom and top of the outer side panel 131. The front cover 134 is fixed to the upper front side of the outer side panel 131 and is provided with control components such as an operation panel. A glass door 135 is provided below the front cover 134. The glass door 135 can slide along the length of both sides of the outer side panel 131 to open or close the front window. The top air inlet 104 and the air outlet 105 are both provided on the top plate 133 to facilitate the intake and exhaust of air. The bottom air inlet 102 is provided on the bottom plate 132, for example, the bottom air inlet 102 is provided on the front side of the bottom plate 132.

[0102] The workbench 140, inner side panel 150, and partition 160 are all installed inside the outer casing 130. The workbench 140 and inner side panel 150 enclose the working area 101. The workbench 140 and the base plate 132 are spaced apart to form a bottom air duct 113. A drip tray 136 is provided between the workbench 140 and the base plate 132 to collect condensate and other generated water.

[0103] The inner side panel 150 includes a rear side panel and two side panels disposed on both sides of the rear side panel. The rear side panel and the back side panel of the outer side panel 131 are spaced apart to form part of the back air duct 114.

[0104] A partition 160 is fixed between the inner side panel 150 and the top panel 133, and is fixedly connected to the top end of the inner side panel 150 and the top panel 133 respectively. A gap exists between the partition 160 and the back side panel of the outer side panel 131, forming part of the back air duct 114; a gap exists between the partition 160 and the front cover 134 to form a second air duct 120. A connecting port 161 connecting the first air duct 110 and the second air duct 120 is provided on the partition 160. The shape of the partition 160 is not limited in this embodiment, as long as sufficient space is provided for the second air duct 120 and the back air duct 114 to install a fan and a filter.

[0105] Thus, the back air duct 114 in this embodiment includes the gap between the partition 160 and the outer side panel 131, and the gap between the inner side panel 150 and the outer side panel 131.

[0106] It should be noted that the structure of the cabinet 100 is not limited to the above structure, as long as it can form the air duct structure in the embodiment of this application.

[0107] In summary, the biosafety cabinet of this embodiment has a first control valve 220 installed at the top air inlet 104. When the operating voltage of the air supply unit 121 is greater than or equal to a preset first voltage threshold, the first control valve 220 is configured to open to its maximum opening. By adjusting the operating voltage of the air supply unit 121, the rotation speed of the air supply unit 121 is adjusted, thereby adjusting the first airflow speed of the biosafety cabinet, making the adjustment of the first airflow speed rapid and quick. When the operating voltage of the air supply unit 121 is less than the first voltage threshold, the air supply unit 121 is configured to operate according to the first voltage. By adjusting the opening angle of the first control valve 220, the first airflow speed of the biosafety cabinet is adjusted. This allows for flexible adjustment of the first airflow speed and avoids excessive noise caused by excessively low operating voltage of the air supply unit 121. This embodiment combines adjusting the air supply unit 121 and adjusting the opening angle of the first control valve 220 to adjust the first airflow speed of the biosafety cabinet, ensuring that the first airflow speed meets the first target airflow speed and avoiding excessive noise from the biosafety cabinet, thus meeting the noise requirements of the biosafety cabinet.

[0108] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A biosafety cabinet, characterized in that, include: Cabinet; The cabinet encloses a working area with an opening at the front. A bottom air inlet is located below the front of the working area, and an air outlet is located at the top of the working area. A top air inlet and an air outlet are also located at the top of the cabinet. A first control valve is installed at the top air inlet, configured to control the opening or closing of the top air inlet. A first wind speed sensor is located within the working area, used to detect the wind speed blowing from the air outlet towards the working area. The cabinet contains a first air duct and a second air duct. The two ends of the first air duct are connected to the bottom air inlet and the air outlet, respectively. The two ends of the second air duct are connected to the top air inlet and the air outlet, respectively. An air supply unit is installed at the end of the second air duct near the air outlet, and the air supply unit includes an air supply fan. The air supply unit is configured to determine the operating voltage of the air supply unit based on the first wind speed when the operating voltage of the air supply unit is greater than or equal to a preset first voltage threshold, and the first control valve is configured to open to the maximum opening. When the operating voltage of the air supply unit is less than the first voltage threshold, the air supply unit is configured to operate according to the first voltage, and the first control valve is configured to determine the opening and closing angle of the first control valve according to the first wind speed, wherein the first voltage is greater than or equal to the first voltage threshold. The air outlet is connected to an outdoor exhaust pipe, and a second control valve is installed in the outdoor exhaust pipe. The second control valve is configured to control the outdoor exhaust pipe to open or close. An exhaust unit is installed at one end of the first air duct near the air outlet; the exhaust unit includes an exhaust fan. When the first control valve is configured to open, the second control valve is configured to open; the exhaust unit is configured to start so that the gas drawn in by the bottom air inlet is discharged through the first air duct, the air outlet and the outdoor exhaust pipe; the air supply unit is configured to start so that the gas drawn in by the top air inlet is blown to the working area through the second air duct and the air supply outlet. The air outlet is equipped with a second wind speed sensor, which is used to detect the second wind speed blowing out of the air outlet. The exhaust unit is configured to determine the operating voltage of the exhaust unit based on the second wind speed when the operating voltage of the exhaust unit is greater than or equal to a preset second voltage threshold; the second control valve is configured to open to its maximum opening. When the operating voltage of the exhaust unit is less than the second voltage threshold, the exhaust unit is configured to operate according to the second voltage, and the second control valve is configured to determine the opening and closing angle of the second control valve according to the second wind speed, wherein the second voltage is greater than or equal to the second voltage threshold; The first control valve includes a valve plate and a linear actuator, both of which are located inside the cabinet. One end of the valve plate is hinged to the cabinet on the side of the top air inlet, and the other end of the valve plate is hinged to the output end of the linear actuator. The linear actuator is fixed relative to the cabinet. When the output end of the linear actuator extends, the valve plate is sealed to the top air inlet to close the top air inlet; when the output end of the linear actuator retracts, the valve plate rotates relative to the top air inlet to open the top air inlet; the linear actuator is configured to determine the extension length of the output end of the linear actuator based on the first wind speed to determine the opening and closing angle of the first control valve.

2. The biosafety cabinet according to claim 1, characterized in that, When the first wind speed is less than the preset first target wind speed, the opening angle of the first control valve increases; when the first wind speed is greater than the first target wind speed, the opening angle of the first control valve decreases.

3. The biosafety cabinet according to claim 1, characterized in that, When the first wind speed is less than the preset first target wind speed, the operating voltage of the air supply unit increases; when the first wind speed is greater than the first target wind speed, the operating voltage of the air supply unit decreases.

4. The biosafety cabinet according to claim 1, characterized in that, The top air inlet is provided with a first sealing ring at its edge, and the first sealing ring abuts against the top surface of the valve plate to seal. The bottom surface of the top air inlet is provided with an annular mounting groove, and a second sealing ring is provided in the mounting groove. The second sealing ring abuts against the circumferential side of the valve plate for sealing.

5. The biosafety cabinet according to claim 1, characterized in that, A trigger switch is provided between the valve plate and the cabinet body where the top air inlet is located; the biosafety cabinet is equipped with an alarm device; When the linear actuator is configured to drive the valve plate to seal with the top air inlet, the trigger switch sends a closing signal; when the linear actuator is configured to drive the valve plate to seal with the top air inlet and the trigger switch does not send a closing signal, the alarm device sends an alarm signal.

6. The biosafety cabinet according to any one of claims 1-5, characterized in that, An air inlet filter is installed on the top surface of the top air inlet.

7. The biosafety cabinet according to any one of claims 1-5, characterized in that, There are two air supply units, which are arranged at intervals along the length of the cabinet and are symmetrically distributed at opposite ends of the top air inlet. There are two first wind speed sensors, and the two first wind speed sensors are respectively located at both ends of the cabinet in the length direction; The air supply unit is configured to determine its operating voltage based on a first wind speed detected by the first wind speed sensor at the same end of the air supply unit when the operating voltage of the air supply unit is greater than or equal to the first voltage threshold.

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