A biosafety cabinet

Abstract

This invention relates to the field of medical device technology, and in particular to a biosafety cabinet, comprising a cabinet body, a lower chamber for housing automated testing equipment, and an upper chamber arranged above the lower chamber; an air supply device is provided in the upper chamber, with its air inlet communicating with the upper chamber and its air outlet communicating with the lower chamber; an air inlet communicating with the outside is provided on the top or periphery of the upper chamber; the side wall of the lower chamber includes at least one cabinet door for sealing the lower chamber, the cabinet door being a shell, the inner cavity of the shell forming a return air channel, and a first ventilation structure being provided on the inner side of the shell, the first ventilation structure communicating with the bottom of the lower chamber and the return air channel; a second ventilation structure being provided on the top of the shell, the second ventilation structure communicating with the return air channel and the upper chamber; the inner cavity of the cabinet door shell forming a return air channel is large and does not require additional air ducts, ensuring that the airflow in the lower chamber for housing automated equipment can flow evenly and fully.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a biosafety cabinet. Background Technology

[0002] In medical testing procedures such as blood tests, the application of automated equipment brings numerous advantages. First, automated equipment can quickly and accurately complete complex testing tasks, reducing errors that may be caused by human operation and improving the reliability and consistency of test results. Second, automated systems can operate continuously, without being limited by the time and intensity of manual operation, significantly enhancing the laboratory's testing capabilities. Furthermore, automated equipment can integrate multiple testing modules, enabling one-stop multi-item testing, improving the overall work efficiency of the laboratory. The application of automated testing equipment in the medical field is becoming increasingly widespread.

[0003] Biochemical tests, such as blood tests, often require a sterile environment, necessitating the placement of the corresponding automated testing equipment within a biosafety cabinet. Biosafety cabinets require precise airflow control to maintain a sterile environment. Biosafety cabinets housing automated testing equipment are larger than standard biosafety cabinets, and the automated equipment generates heat during operation. Maintaining a suitable temperature and ensuring uniform and sufficient airflow within the cabinet is crucial for biosafety cabinets housing automated equipment.

[0004] Chinese utility model patent CN215087236U discloses an energy-saving biosafety cabinet, including a cabinet body and a filtration system. The cabinet body has an air inlet and an air outlet connecting its working area. The filtration system includes an air supply component connected to the air inlet, an air outlet component connected to the air outlet, and a fan. A return pipe is connected between the air supply component and the air outlet component, and a one-way valve is installed on the return pipe. Under the operation of the filtration system, the gas in the working area inside the cabinet circulates. The hot airflow discharged from the air outlet component returns to the air supply component through the return pipe, and then returns to the cabinet again through the air supply component, thus maintaining a stable temperature inside the biosafety cabinet.

[0005] However, biosafety cabinets used to set up automated testing equipment are large in size and require high airflow during air exchange. They use return pipes to transport air into the cabinet, which requires the return pipes to be large and the air inlets of the return pipes to be distributed in a small range, making it difficult to ensure that the airflow inside the cabinet is uniform and sufficient. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the existing biosafety cabinets circulate the air inside the cabinet to the air inlet through the manifold, and the air inlet distribution range of the return pipe is small, making it difficult to ensure uniform and sufficient airflow inside the cabinet.

[0007] To address the aforementioned technical problems, the present invention aims to provide a biosafety cabinet, comprising a cabinet body, wherein the cabinet body has a lower chamber for housing automated detection equipment and an upper chamber arranged above the lower chamber; the upper chamber is provided with an air supply device, the air inlet of the air supply device is connected to the upper chamber, the air outlet of the air supply device is connected to the lower chamber, and the top or periphery of the upper chamber is provided with an air inlet connecting to the outside.

[0008] The side wall of the lower chamber includes at least one cabinet door for sealing the lower chamber. The cabinet door is a shell, and the inner cavity of the shell forms a return air channel. The inner side of the shell is provided with a first ventilation structure, which connects the bottom of the lower chamber with the return air channel. The top of the shell is provided with a second ventilation structure, which connects the return air channel with the upper chamber.

[0009] As a preferred embodiment, the biosafety cabinet includes a static pressure chamber and a first filter plate. The static pressure chamber is installed in the upper part of the cabinet cavity, and the chamber wall of the static pressure chamber divides the cabinet cavity into the upper chamber and the lower chamber.

[0010] The air outlet of the air supply device is connected to the inner cavity of the static pressure box. The lower end of the static pressure box has a first air outlet. The first filter plate is disposed in the upper part of the lower chamber to block the first air outlet.

[0011] As a preferred embodiment, the upper end of the static pressure box is provided with a second air outlet, and the upper end of the static pressure box is connected to a second filter plate for sealing the second air outlet;

[0012] The filtration pressure of the first filter plate is the same as that of the second filter plate.

[0013] As a preferred embodiment, the biosafety cabinet further includes a control system, a temperature sensor is provided in the lower chamber, and a flow control valve is provided in the second air outlet. The flow control valve, the temperature sensor, and the air supply device are all electrically connected to the control system.

[0014] When the temperature sensor reading is too high, the control system controls the flow control valve to increase its speed and the air supply device to increase its air supply power; when the temperature sensor reading is too low, the control system controls the flow control valve to decrease its speed and the air supply device to decrease its air supply power.

[0015] As a preferred embodiment, a wind speed sensor is provided in the lower chamber, the wind speed sensor is arranged below the first filter plate, and the wind speed sensor is electrically connected to the control system;

[0016] When the wind speed sensor reading is too low, the control system controls the air supply device to increase the air supply power; when the wind speed sensor reading is too high, the control system controls the air supply device to decrease the air supply power.

[0017] As a preferred embodiment, the air outlet direction of the air supply device is inclined toward the first filter plate.

[0018] As a preferred embodiment, the upper part of the lower chamber is provided with a diffuser plate, which is arranged below the first filter plate, and the diffuser plate is provided with a plurality of diffuser holes at intervals.

[0019] As a preferred embodiment, a third filter plate for sealing the air inlet is provided at the air inlet.

[0020] As a preferred embodiment, a magnetic sealing ring is fixed to one end of the cabinet door opposite to the door frame, and the magnetic sealing ring is attracted to the door frame.

[0021] As a preferred embodiment, the first ventilation structure consists of multiple return air holes distributed in the lower inner part of the housing.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The biosafety cabinet of the present invention includes a cabinet body, the cabinet body having a lower chamber for placing automated testing equipment and an upper chamber arranged above the lower chamber; an air supply device is provided in the upper chamber, the air inlet of the air supply device is connected to the upper chamber, and the air outlet of the air supply device is connected to the lower chamber; an air inlet connected to the outside is provided on the top or periphery of the upper chamber; the side wall of the lower chamber includes at least one cabinet door for sealing the lower chamber, the cabinet door being a shell, the inner cavity of the shell forming a return air channel, the inner side of the shell having a first ventilation structure, the first ventilation structure connecting the bottom of the lower chamber to the return air channel; the top of the shell having a second ventilation structure, the second ventilation structure connecting the return air channel to the upper chamber; in this application, the cabinet door is set as a shell, the inner cavity of the shell forming a return air channel, the return air channel being large and not requiring additional air ducts, ensuring that the airflow in the lower chamber for placing automated equipment can flow evenly and fully. Attached Figure Description

[0024] Figure 1 This is a front view of the biosafety cabinet of the present invention;

[0025] Figure 2 for Figure 1 Sectional view along the AA direction;

[0026] Figure 3 for Figure 1 Cross-sectional view along the BB direction;

[0027] Figure 4This is a side view of the biosafety cabinet of the present invention;

[0028] Figure 5 for Figure 4 Cross-sectional view along the CC direction;

[0029] Figure 6 This is a structural diagram of the cabinet door;

[0030] Figure 7 for Figure 6 Cross-sectional view along the DD direction;

[0031] Figure 8 for Figure 7 Enlarged view of a section at point E in the middle;

[0032] In the diagram, 1. Cabinet body, 12. Upper chamber, 121. Air inlet, 13. Cabinet door, 131. Return air duct, 132. Return air vent, 133. Inner panel, 134. Outer panel, 135. Long slot, 2. Fan, 3. Static pressure box, 31. Box body, 311. First air outlet, 312. Second air outlet, 32. Flange plate, 41. First filter plate, 42. Second filter plate, 43. Third filter plate, 5. Diffuser plate, 6. Magnetic sealing ring. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. It should be understood that the terms "first," "second," etc., are used in this invention to describe various information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this invention, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information.

[0035] like Figures 1 to 8As shown, a preferred embodiment of the biosafety cabinet of the present invention includes a cabinet body 1. The cabinet body 1 has a lower chamber for placing automated testing equipment and an upper chamber 12 arranged above the lower chamber. An air supply device is provided in the upper chamber 12. The air inlet of the air supply device is connected to the upper chamber 12, and the air outlet of the air supply device is connected to the lower chamber. An air inlet 121 connecting to the outside is provided on the top or periphery of the upper chamber 12. The side wall of the lower chamber includes at least one cabinet door 13 for sealing the lower chamber. The cabinet door 13 is a shell. The inner cavity of the shell forms a return air channel 131. A first ventilation structure is provided on the inner side of the shell. The first ventilation structure connects the bottom of the lower chamber with the return air channel 131. A second ventilation structure is provided on the top of the shell. The second ventilation structure connects the return air channel 131 with the upper chamber 12. By setting the cabinet door 13 as the shell, the inner cavity of the shell forms a return air channel 131. The return air channel 131 is large and does not require additional air ducts, ensuring that the airflow in the lower cavity used to house the automated equipment can flow evenly and fully.

[0036] The first ventilation structure consists of multiple return air holes 132 dispersed on the lower inner side of the housing. The second ventilation structure is a long groove 135 formed on the upper part of the cabinet door 13, extending along the width of the cabinet door 13. The long groove 135 can be located on the top wall or the upper side wall of the cabinet door 13. In this embodiment, the cabinet door 13 includes a square frame, an inner panel 133 located inside the square frame, and an outer panel 134 located outside the square frame. The inner panel 133 is made of 304 stainless steel, and each return air hole 132 is located on the lower part of the 304 stainless steel. The 304 stainless steel has strong durability and corrosion resistance, ensuring the durability of the cabinet door 13. The outer panel 134 is made of cold-rolled steel with powder coating, ensuring the cabinet door 13 is aesthetically pleasing and rust-proof. The inner panel 133 and the square frame, as well as the outer panel 134 and the square frame, are connected by snap-fit ​​connections. The inner panel 133, the outer panel 134, and the square frame together form a return air channel 131. The return air vents 132 are square holes 10 mm long and 40 mm wide, and the return air vents 132 are distributed in a matrix.

[0037] To ensure the airtightness of the cabinet door 13 after it is closed, in this embodiment, a magnetic sealing ring 6 is fixed to the end of the cabinet door 13 opposite to the door frame, and the magnetic sealing ring 6 is attracted to the door frame. Specifically, all cabinet doors 13 are outward-opening. The biosafety cabinet includes a door frame disposed inside the cabinet body 1 and arranged opposite to the cabinet door 13. The door frame is made of ferromagnetic material. The periphery of the cabinet door 13 is provided with a groove that matches the contour of the door frame. A sealing ring is inserted into the groove, and a magnetic strip is embedded in the sealing ring. When the cabinet door 13 is closed, the magnetic strip attracts the door frame, so that the sealing ring is tightly attached to the door frame, ensuring the sealing effect of the biosafety cabinet. The sealing ring is made of soft polyvinyl chloride with good flexibility and elasticity.

[0038] In this embodiment, the cabinet 1 is a cuboid, and cabinet doors 13 are provided on the left, right, and rear sides of the cabinet 1. Each cabinet door 13 is a shell with a first ventilation structure and a second ventilation structure. This further improves the distribution range of the return air vents 132.

[0039] In this embodiment, the biosafety cabinet includes a static pressure chamber 3 and a first filter plate 41. The static pressure chamber 3 is installed in the upper part of the cabinet cavity, and the chamber wall of the static pressure chamber 3 divides the cabinet cavity into an upper chamber 12 and a lower chamber. The air outlet of the air supply device is connected to the inner cavity of the static pressure chamber 3. The lower end of the static pressure chamber 3 has a first air outlet, and the first filter plate 41 is arranged in the upper part of the lower chamber to block the first air outlet. Specifically, the air supply device is a fan 2, and there are four fans 2 arranged at intervals around the periphery of the static pressure box 3. The air outlet of the fan 2 is equipped with a trumpet-shaped diffusion structure with a diffusion angle of 10°. After the four air supply devices draw in air, the air outlet of the fan 2 blows into the static pressure box 3 at a diffusion angle of 10 degrees. This design ensures that air reaches all areas inside the static pressure box 3, improving the uniformity of airflow. The first filter plate 41 is a high-efficiency filter with high filtration accuracy. Under the resistance of the high-efficiency filter, the air entering the static pressure box 3 has increased pressure inside the static pressure box 3, making the air more evenly distributed inside the static pressure box 3. The air inside the static pressure box 3 passes through the first filter plate 41 through pressure and becomes clean air.

[0040] To ensure that clean air is evenly distributed throughout the lower chamber, in this embodiment, a diffuser plate 5 is provided at the upper part of the lower chamber. The diffuser plate 5 is arranged below the first filter plate 41, and multiple diffuser holes are spaced apart on the diffuser plate 5. The clean air undergoes secondary diversion through the diffuser plate 5, making it more evenly distributed throughout the chamber, ensuring air quality and circulation effect within the lower chamber. The diffuser plate 5 ensures that the clean air can be smoothly dispersed, avoiding the generation of eddies or turbulence, and further improving the uniformity and stability of the airflow.

[0041] Due to height restrictions in the installation area, the height of the biosafety cabinet needs to be controlled within a certain range. Furthermore, the lower chamber, serving as the working area, needs to be as high as possible, while the upper chamber 12 should be as low as possible. Therefore, the fan 2, acting as the air supply device, needs to be small in size, capable of overcoming significant resistance, and possess a certain airflow. This type of fan 2 is not only compact but can also provide at least 2500 cubic meters per hour of airflow under resistance conditions of 350 to 400 Pascals. The selection of this type of fan 2 ensures that the required airflow is achieved within a limited space while overcoming the overall resistance of the equipment. In this embodiment, the static pressure box 3 includes a box body 31 with its opening facing downwards. The lower edge of the box body 31 is provided with a flange plate 32 extending horizontally outwards. The edge of the flange plate 32 is connected to the inner side wall of the cabinet 1, thereby connecting the static pressure box 3 to the cabinet 1. The fan 2 is installed outside the side wall of the box body 31 and is located on the flange plate 32. If the air outlet of the fan 2 is arranged horizontally, the air blown out from the fan 2 needs to be blocked by the box wall of the static pressure box 3 and then turned back to the first filter plate 41. This is not conducive to the efficient downward flow of the gas in the static pressure box 3 through the first filter plate 41. Moreover, when the air outlet is arranged horizontally, the air inlet of the fan 2 will be vertically opposite to the flange plate 32. This will result in the distance between the air inlet of the fan 2 and the flange plate 32 being too close, which is not conducive to air intake. In this embodiment, the air outlet direction of the air supply device is arranged at an angle towards the first filter plate 41. Specifically, the air outlet of fan 2 is inclined downwards at 5°, and the air inlet of fan 2 is also inclined relative to the flange plate 32. This improves the air intake efficiency of fan 2, and the air blown by fan 2 is inclined downwards onto the first filter plate 41, which improves the filtration efficiency of the first filter plate 41. In this embodiment, the air inlet of fan 2 is arranged downwards, and the air inlet of fan 2 is spaced vertically from the flange plate 32. This is because when the air inlet of fan 2 is downwards, the axial direction of the impeller of fan 2 is arranged vertically, so the diameter direction of the impeller is close to horizontal. This makes the distance between the highest point of fan 2 and the flange plate smaller, thus avoiding excessively high installation height of the impeller and further reducing the overall height of the biosafety cabinet of the present invention. In addition, the inclined arrangement of fan 2 allows the air inlet of fan 2 to be arranged at an angle to the flange plate 32, avoiding the narrow air intake space caused by the air inlet of fan 2 and the flange plate 32 being directly opposite each other, which is conducive to smooth air intake of fan 2.

[0042] In this embodiment, four air supply devices are provided, all of which are fans 2. The four air supply devices are respectively arranged on the left front side, left rear side, right rear side, and right front side of the housing 31, so that the gas in all parts of the lower chamber can flow back smoothly and efficiently. This improves the efficiency of air circulation inside the entire cabinet 1. This distribution method also helps to reduce the existence of airflow dead zones in local areas of the lower chamber.

[0043] In this embodiment, a third filter plate 43 is provided at the air inlet 121 to block the air inlet 121. The third filter plate 43 is a primary filter, and its filtration accuracy is lower than that of the first filter plate 41, thus achieving primary filtration of the intake air. When each fan 2 is running, under the action of the fan 2, the airflow in the lower chamber flows back to the upper chamber 12 through the return air channel 131. At the same time, the outside air flows into the upper chamber 12 from the air inlet 121 after being filtered by the third filter plate 43. The outside air and the return air are mixed and then enter the static pressure box 3 under the action of the fan 2. The upper end of the static pressure box 3 is provided with a second air outlet 312, and the upper end of the static pressure box 3 is connected to a second filter plate 42 for blocking the second air outlet 312. The filtration pressure of the first filter plate 41 is the same as that of the second filter plate 42.

[0044] During the operation of the biosafety cabinet, part of the gas in the static pressure chamber 3 flows to the lower chamber through the first filter plate 41, and the other part flows to the outside through the second air outlet 312. The ratio of the amount of gas flowing into the lower chamber to the amount of gas flowing out to the outside is the same as the ratio of the cross-sectional areas of the first and second air outlets 312. The gas flowing out of the working room from the second air outlet 312 is filtered by the second filter plate 42, preventing the outflow of microorganisms; the gas blowing into the lower chamber from the second air outlet 312 is filtered by the first filter plate 41, meeting the gas cleanliness requirements of the working chamber. By setting the ratio of the cross-sectional areas of the first and second air outlets 312, the flow rate of the mixed gas in the static pressure chamber 3 to the lower chamber can be controlled, thereby controlling the air exchange rate in the working chamber and regulating the flow rate and temperature of the gas in the working chamber.

[0045] The following describes the ventilation process of the biosafety cabinet of the present invention in detail, taking as an example that the air volume blown into the static pressure box 3 by each fan 2 is 100 cubic meters and the cross-sectional area ratio of the first air outlet and the second air outlet 312 is 7:3. 70 cubic meters of gas entering the static pressure box 3 is filtered by the first filter plate 41 to form a first portion of clean gas. This first portion of clean gas enters the lower chamber. Since the volume of the lower chamber is constant, as the first portion of clean gas flows from the upper part of the lower chamber to the lower part of the lower chamber, the original equal amount of gas in the lower chamber flows into the return air channel 131 through the return air hole 132 and then through the return air channel 13... 1. The air flows into the upper chamber 12, meaning the return flow of the original gas in the lower chamber is also 70 cubic meters. The air output of each fan 2 is 100 cubic meters, and the air intake also needs to be 100 cubic meters. Therefore, 30 cubic meters of fresh air flow into the upper chamber 12 from the air inlet 121. The 30 cubic meters of fresh air mixes with the 70 cubic meters of return air and enters the static pressure box 3. The gas circulates repeatedly, realizing the circulation and renewal of the gas in the lower chamber, thereby maintaining the gas temperature in the lower chamber. Through the above analysis, it can be seen that the amount of clean gas flowing out of the cabinet 1 from the second air outlet 312 is equal to the amount of fresh air flowing into the lower chamber from the air inlet 121.

[0046] To regulate the gas temperature in the lower chamber, this embodiment of the biosafety cabinet also includes a control system. A temperature sensor is installed in the lower chamber, and a flow control valve is installed in the second air outlet 312. The flow control valve, temperature sensor, and air supply device are all electrically connected to the control system. When the temperature sensor reading is too high, the control system increases the flow control valve and the air supply device's power output. Increasing the flow control valve increases the ratio of the cross-sectional area of ​​the second air outlet 312 to the first air outlet, thereby increasing the ratio of the amount of clean gas discharged outside the cabinet to the amount of clean gas flowing into the lower chamber. Simultaneously, it increases the power of the air supply device. The ratio of clean gas in the lower chamber to clean gas flowing out of cabinet 1 decreases, but the total gas volume increases. Therefore, the total amount of clean gas flowing into the lower chamber remains constant, thus maintaining a constant air exchange rate in the lower chamber. Since the amount of fresh gas entering the lower chamber from air inlet 121 is equal to the amount of clean gas flowing out of cabinet 1 from the second air outlet 312, the proportion of fresh air in the mixed gas in the static pressure box 3 increases, thereby achieving temperature regulation of the mixed gas in the static pressure box 3. When the temperature sensor reading is low, the control system controls the flow control valve to reduce its speed and controls the air supply device to reduce its air supply power.

[0047] Furthermore, a wind speed sensor is installed in the lower chamber, which is located below the first filter plate 41. Both the wind speed sensor and the air supply device are electrically connected to the control system. When the test value of the wind speed sensor is too low, the control system controls the air supply device to increase the air supply power. When the test value of the wind speed sensor is too high, the control system controls the air supply device to decrease the air supply power.

[0048] Specifically, without changing the opening of the flow regulating valve, increasing the operating power of fan 2 can increase the air exchange volume, while decreasing the operating power of fan 2 can reduce the air exchange volume, thereby achieving the regulation of the airflow velocity in the lower chamber.

[0049] In summary, the biosafety cabinet of the present invention includes a cabinet body 1. The cabinet body 1 has a lower chamber for housing automated testing equipment and an upper chamber 12 arranged above the lower chamber. An air supply device is provided in the upper chamber 12, with its air inlet communicating with the upper chamber 12 and its air outlet communicating with the lower chamber. An air inlet 121 communicating with the outside is provided on the top or periphery of the upper chamber 12. The side wall of the lower chamber includes at least one cabinet door 13 for sealing the lower chamber. The cabinet door 13 is a shell, and the inner cavity of the shell forms a return air channel 131. The inner side of the cabinet is provided with a first ventilation structure, which connects the bottom of the lower chamber to the return air channel 131; the top of the cabinet is provided with a second ventilation structure, which connects the return air channel 131 to the upper chamber 12; in this application, the cabinet door 13 is set as the cabinet, and the inner cavity of the cabinet forms the return air channel 131. The return air channel 131 is large and does not require additional air ducts, ensuring that the airflow in the lower chamber used to house the automated equipment can flow evenly and fully; thus meeting the requirements for the stable operation of the automated equipment in the biosafety cabinet and the conduct of biochemical experiments.

[0050] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A biosafety cabinet, characterized in that, The system includes a cabinet (1), which has a lower chamber for placing automated testing equipment and an upper chamber (12) arranged above the lower chamber. The upper chamber (12) is equipped with an air supply device, the air inlet of which is connected to the upper chamber (12), the air outlet of which is connected to the lower chamber, and the top or periphery of the upper chamber (12) is provided with an air inlet (121) that connects to the outside. The lower chamber has a side wall including at least one cabinet door (13) for sealing the lower chamber. The cabinet door (13) is a shell. The inner cavity of the shell forms a return air channel (131). The inner side of the shell is provided with a first ventilation structure, which connects the bottom of the lower chamber with the return air channel (131). The top of the shell is provided with a second ventilation structure, which connects the return air channel (131) with the upper chamber (12). The biosafety cabinet includes a static pressure box (3) and a first filter plate (41). The static pressure box (3) is installed in the upper part of the cabinet cavity. The box wall of the static pressure box (3) divides the cabinet cavity into the upper chamber (12) and the lower chamber. The air outlet of the air supply device is connected to the inner cavity of the static pressure box (3). The lower end of the static pressure box (3) has a first air outlet. The first filter plate (41) is disposed in the upper part of the lower chamber to block the first air outlet. The upper end of the static pressure box (3) is provided with a second air outlet (312), and the upper end of the static pressure box (3) is connected to a second filter plate (42) for sealing the second air outlet (312). The filtration pressure of the first filter plate (41) is the same as that of the second filter plate (42). The ratio of the amount of gas flowing into the lower chamber of the static pressure box (3) to the amount of gas flowing out to the outside is the same as the ratio of the cross-sectional area of ​​the first air outlet and the second air outlet (312). The biosafety cabinet also includes a control system. A temperature sensor is provided in the lower chamber. A flow control valve is provided in the second air outlet (312). The flow control valve can adjust the ratio of the cross-sectional area of ​​the second air outlet (312) to that of the first air outlet. The flow control valve, the temperature sensor, and the air supply device are all electrically connected to the control system. When the temperature sensor reading is too high, the control system controls the flow control valve to increase its speed and the air supply device to increase its air supply power. When the temperature sensor reading is too low, the control system controls the flow control valve to decrease its speed and the air supply device to decrease its air supply power, so as to keep the total amount of clean gas flowing into the lower chamber constant.

2. The biosafety cabinet according to claim 1, characterized in that, A wind speed sensor is provided in the lower chamber. The wind speed sensor is arranged below the first filter plate (41). The wind speed sensor is electrically connected to the control system. When the wind speed sensor reading is too low, the control system controls the air supply device to increase the air supply power; when the wind speed sensor reading is too high, the control system controls the air supply device to decrease the air supply power.

3. The biosafety cabinet according to claim 1, characterized in that, The air outlet direction of the air supply device is inclined toward the first filter plate (41).

4. The biosafety cabinet according to claim 1, characterized in that, The upper part of the lower chamber is provided with a diffuser plate (5), which is arranged below the first filter plate (41). The diffuser plate (5) is provided with a plurality of diffuser holes at intervals.

5. The biosafety cabinet according to claim 1, characterized in that, A third filter plate (43) for sealing the air inlet (121) is provided at the air inlet (121).

6. The biosafety cabinet according to claim 1, characterized in that, A magnetic sealing ring (6) is fixed at one end of the cabinet door (13) opposite to the door frame, and the magnetic sealing ring (6) is attracted to the door frame.

7. The biosafety cabinet according to claim 1, characterized in that, The first ventilation structure consists of multiple return air holes (132) distributed on the lower inner side of the housing.

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