Exhaust system for medicine cleaning workshop

Abstract

The exhaust system for the medicine cleaning workshop comprises a process exhaust branch pipe, a general exhaust branch pipe, an exhaust fan and an air duct switching valve, and the process exhaust branch pipe and the general exhaust branch pipe are gathered through the air duct switching valve and connected to an inlet of the exhaust fan. The air duct switching valve has at least two working states: in the first working state, the process exhaust branch pipe is conducted, and the general exhaust branch pipe is blocked; and in the second working state, the general exhaust branch pipe is conducted, and the process exhaust branch pipe is blocked, through the structure, automatic switching between process exhaust and general exhaust can be achieved in the same exhaust system, and energy consumption and control complexity brought by a multi-fan system are avoided.

Description

Technical Field

[0001] This invention relates to the field of fresh air treatment technology, and more specifically, to an exhaust system for pharmaceutical cleanrooms. Background Technology

[0002] In cleanrooms of high-end manufacturing industries such as pharmaceuticals, integrated circuits, and flat panel displays, the operation of process equipment often necessitates significant process exhaust ventilation. For example, in pharmaceutical production workshops, when process equipment is running, process exhaust ventilation must be activated to remove harmful gases, dust, or excess heat generated, ensuring operator safety and product quality. Simultaneously, to maintain the necessary pressure gradient (positive or negative) between the cleanroom and the external environment or adjacent areas to prevent cross-contamination, a continuously operating general exhaust ventilation system is also required.

[0003] In existing technologies, to address the problem of energy waste, some ventilation systems focusing on energy recovery have emerged. For example, international publication number WO2021013048A1 discloses an energy-saving ventilation system utilizing process exhaust air. This system, by incorporating an exhaust air reuse device, aims to transfer the "usable process exhaust air" itself and / or its energy back to the production room and / or the fresh air unit inlet. Its technical approach mainly falls into two categories: one is to directly return clean, ambient-temperature exhaust air to the room after filtration through an independent "process exhaust air reuse unit," thereby reducing the amount of fresh air replenishment; the other is to install a first exhaust fan and parallel first and second exhaust ducts, and use valve switching to guide high-temperature or low-temperature process exhaust air to the fresh air inlet for direct mixing or indirect energy recovery through a heat recovery unit.

[0004] However, existing technologies based on the core concept of "energy recovery" have significant limitations when applied to scenarios such as pharmaceutical workshops, where the stability of operating conditions and system reliability are extremely important.

[0005] 1. System complexity and high cost: In order to achieve energy recovery, it is necessary to add independent recycling units, heat recovery units, complex parallel pipelines and multiple control valves, resulting in high initial investment, large space occupation and increased maintenance complexity.

[0006] 2. Inability to resolve pressure stability issues under intermittent exhaust conditions: The existing technology is designed based on the premise that process exhaust air is continuous and can be recycled. However, in pharmaceutical workshops, the start-up and shutdown of process equipment are common occurrences, leading to drastic fluctuations in process exhaust air volume, sometimes even dropping to zero. When process equipment is shut down and process exhaust stops, according to the existing technology system, the reuse unit or primary exhaust fan will cease operation, causing the room to lose necessary exhaust air and thus failing to maintain a stable pressure differential in the cleanroom, posing a significant risk of cross-contamination.

[0007] 3. Equipment Redundancy: In order to maintain workshop pressure even when process exhaust stops, in practice, it is necessary to connect an independent, continuously operating general exhaust system and its dedicated fan in parallel for this type of "energy recovery system". This essentially creates two parallel exhaust systems, resulting in equipment redundancy and wasted investment, which contradicts the original intention of energy conservation and emission reduction.

[0008] Therefore, there is an urgent need in this field for a new type of exhaust system that can fundamentally solve the problem of smooth connection between process exhaust and non-process exhaust conditions, and achieve system simplification and resource conservation while ensuring absolute stability of workshop pressure. Summary of the Invention

[0009] In view of this, in order to solve the problems of independent configuration of process equipment exhaust systems and general room exhaust systems in existing pharmaceutical cleanrooms, fan redundancy, inconsistent control, complex switching, and the risk of cross-contamination, this invention proposes a pharmaceutical cleanroom exhaust system with a compact structure that allows process exhaust and general exhaust to share a single exhaust fan, and has automatic duct switching capability and clean sealing performance. It enables precise switching between the two types of exhaust branch pipes under different working conditions, thereby significantly improving the operating efficiency and maintenance convenience of the exhaust system while meeting the cleanliness level control requirements.

[0010] An exhaust system for a pharmaceutical cleanroom includes:

[0011] Process exhaust branch pipes are used to connect to process equipment;

[0012] Typical exhaust branch pipes are used to connect cleanroom spaces;

[0013] Exhaust fan;

[0014] And a duct switching valve;

[0015] The process exhaust branch pipe and the general exhaust branch pipe are converged through the duct switching valve and connected to the inlet of the exhaust fan; the duct switching valve is configured to have at least two operating states:

[0016] In the first working state, the passage from the process exhaust branch pipe to the exhaust fan is opened, while the general exhaust branch pipe is blocked.

[0017] In the second operating state, the passage from the general exhaust branch pipe to the exhaust fan is opened, while the process exhaust branch pipe is blocked.

[0018] In some embodiments, the duct switching valve includes a housing having interfaces respectively communicating with the process exhaust branch pipe, the general exhaust branch pipe and the exhaust fan inlet; a first valve plate and a second valve plate rotatably disposed within the housing; and a driving device for driving the first valve plate and the second valve plate to rotate synchronously.

[0019] The first valve plate and the second valve plate are configured to be fixedly connected in an L-shape, and can be switched between the first working state and the second working state by the drive device.

[0020] Specifically, the first valve plate and the second valve plate are set at a fixed angle through a shared rotating shaft. When the first valve plate and the second valve plate rotate to open the exhaust path, the second valve plate rotates to the sealing position, thereby realizing the interlocking switching of the two passages inside the housing.

[0021] In some embodiments, the drive device is an electric actuator or a pneumatic actuator.

[0022] Specifically, the electric actuator is an electric valve head located outside the housing, with its output shaft connected to the rotating shaft, used to receive control signals and drive the first valve plate and the second valve plate to rotate to a predetermined angle.

[0023] In some embodiments, the duct switching valve further includes a limiting mechanism for limiting the rotation angle of the first valve plate and the second valve plate to ensure that it is accurately switched to the first working state or the second working state.

[0024] Specifically, the limiting mechanism includes a limiting block and a mechanical stop structure, which are respectively set on the rotating shaft or the housing structure to prevent the first valve plate and the second valve plate from rotating beyond the design angle.

[0025] In some embodiments, the duct switching valve further includes a sealing structure disposed between the inner wall of the housing and the closed edges of the first valve plate and the second valve plate, for forming a seal when the duct is blocked.

[0026] Specifically, the sealing structure is arranged along the inner wall of the housing to form a contact area with the contact surfaces of the first valve plate and the second valve plate, and makes sealing contact with them when the first valve plate and the second valve plate are closed to block gas leakage.

[0027] Furthermore, the sealing structure is an elastic sealing strip disposed on the closed edge of the first valve plate, the second valve plate, or the inner wall of the housing.

[0028] Specifically, the elastic sealing strip is made of EPDM rubber or silicone material and is fixed to the edge of the first valve plate, the second valve plate or the corresponding position of the housing by means of a slot, and has the ability to compress and deform to enhance the sealing effect.

[0029] In some embodiments, the first valve plate and the second valve plate maintain a blocking state on at least one of the process exhaust branch pipe and the general exhaust branch pipe at any position during their rotation stroke.

[0030] Specifically, the L-shaped structure ensures that at least one side of the first valve plate and the second valve plate is in contact with the air duct opening at any rotation angle, thus preventing both air ducts from being open at the same time.

[0031] In some embodiments, a controller is also included, which is signal-connected to the drive device of the air duct switching valve, and is used to control the air duct switching valve to automatically switch between the first working state and the second working state according to the operating state of the process equipment.

[0032] In some embodiments, the controller is also connected to a pressure sensor signal for detecting workshop pressure; the controller is configured to adjust the operating state of the duct switching valve according to the signal from the pressure sensor to maintain stable pressure in the cleanroom.

[0033] Specifically, the controller has built-in control logic that automatically controls the air duct switching valve to switch to the process exhaust passage when a process equipment start signal is detected; and returns to the normal exhaust passage when the equipment is shut down.

[0034] In some embodiments, the housing of the air duct switching valve is provided with an observation window or maintenance port.

[0035] Specifically, the observation window is a transparent viewing window structure located on the side wall of the housing, used for manually observing the position status of the valve plate or its internal operation without stopping the machine.

[0036] In some embodiments, the first valve plate and the second valve plate are made of corrosion-resistant materials and / or have an anti-condensation coating on their surfaces.

[0037] Specifically, the first valve plate and the second valve plate are made of 304 stainless steel or aluminum alloy, with a polytetrafluoroethylene anti-corrosion coating sprayed on the surface and a hydrophilic anti-condensation coating applied to adapt to the humid exhaust environment.

[0038] In some embodiments, the duct switching valve has a modular structure, and its housing, first valve plate, second valve plate, and drive device are detachably connected.

[0039] The beneficial effects of this invention are as follows: This invention proposes an exhaust system for pharmaceutical cleanrooms, including process exhaust branch pipes, general exhaust branch pipes, duct switching valves, exhaust fans, and controllers. The process exhaust branch pipes and general exhaust branch pipes converge and connect to the exhaust fan inlet via the duct switching valve, achieving the merging and sharing of two types of exhaust paths. The duct switching valve has an L-shaped linkage structure with a first valve plate and a second valve plate, synchronously controlled by an electric or pneumatic drive device, achieving interlocking switching between two operating states, ensuring that only one duct is connected at any given time, effectively preventing cross-flow and positive pressure backflow. The duct switching valve has a limiting mechanism and a sealing structure; the first and second valve plates form a mechanical stop and elastic fit at the rotating end, ensuring the accuracy and sealing of the duct switching action. The controller establishes a logical linkage relationship with the process equipment operating signals and the cleanroom differential pressure sensor, automatically adjusting the duct switching valve state according to equipment start / stop and differential pressure fluctuations, achieving on-demand exhaust and cleanroom isolation. While ensuring that process exhaust air is prioritized during equipment operation and general exhaust ventilation is automatically restored when the equipment is shut down, a single exhaust fan can meet both exhaust needs, significantly reducing system equipment configuration and energy consumption, and improving the reliability and resource utilization efficiency of cleanroom operation. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0041] Figure 2 This is an AA cross-sectional view of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0042] Figure 3 This is a schematic sectional view (AA) of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0043] Figure 4 This is a schematic diagram of the connection structure between the first valve plate, the second valve plate, and the drive device of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0044] Figure 5 This is a partially enlarged schematic diagram of point C of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0045] Figure 6 This is a partially enlarged schematic diagram of point D of the exhaust system for a pharmaceutical cleanroom according to the present invention.

[0046] Explanation of main component symbols

[0047] 10 process exhaust branch pipes;

[0048] Typical exhaust branch pipe 20;

[0049] 30 exhaust fan;

[0050] Duct switching valve 40;

[0051] Housing 50; First valve plate 51; Second valve plate 52; Drive device 53; Limiting mechanism 54; Limiting block 55; Sealing structure 56; Mechanical stop structure 57; Elastic sealing strip 58; Rotating shaft 59;

[0052] Controller 60.

[0053] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation Example 1:

[0054] Traditional pharmaceutical cleanroom exhaust systems generally suffer from the following limitations in unifying the treatment of process exhaust and general exhaust: Firstly, multi-channel exhaust systems typically rely on separate fans and exhaust branch pipes, resulting in complex system structures, high energy consumption, and an inability to achieve unified control and intelligent linkage between the two air ducts. Secondly, common valve switching structures mostly employ manual valve assemblies or non-interlocking dampers, which present risks such as delayed switching response, path interference, and misoperation, especially during seasonal changes or frequent equipment start-ups and shutdowns, easily leading to operational hazards such as pressure fluctuations and cross-contamination in the clean area. Furthermore, the lack of dedicated interlocking structures and sealing mechanisms within the valves results in the risk of gas leakage or simultaneous conduction of both paths during air duct switching, severely impacting the stability of the clean environment and the operational reliability of the system.

[0055] To address the aforementioned issues, the applicant recognized the need to develop a structurally integrated and intelligently operated duct switching and exhaust system solution that simultaneously meets multiple technical requirements, including efficient duct switching, airtightness control, and automation integration.

[0056] like Figure 1 As shown, this application proposes an exhaust system for a pharmaceutical cleanroom, comprising:

[0057] Process exhaust branch pipe 10 is used to connect process equipment;

[0058] A standard exhaust branch pipe of 20mm is used to connect to the cleanroom space.

[0059] 30 exhaust fan;

[0060] And a duct switching valve 40;

[0061] The process exhaust branch pipe 10 and the general exhaust branch pipe 20 are converged and connected to the inlet of the exhaust fan 30 via the duct switching valve 40; the duct switching valve 40 is configured to have at least two operating states:

[0062] In the first working state, the passage from the process exhaust branch pipe 10 to the exhaust fan 30 is opened, while the general exhaust branch pipe 20 is blocked.

[0063] In the second working state, the passage from the general exhaust branch pipe 20 to the exhaust fan 30 is opened, while the process exhaust branch pipe 10 is blocked.

[0064] In the prior art, traditional exhaust systems often use branch control or multiple independent exhaust fans 30 to handle process exhaust and general exhaust separately, resulting in complex system structure, high energy consumption, and inconvenient switching. This application sets up an integrated duct switching valve 40 to converge the process exhaust branch pipe 10 and the general exhaust branch pipe 20 to the inlet of the same exhaust fan 30. By controlling the opening and closing of different airflow paths through two working states inside the duct switching valve 40, the purpose of flexibly and efficiently switching different exhaust channels in the same exhaust system is achieved.

[0065] like Figure 2-6 As shown, the duct switching valve 40 includes a housing 50 with interfaces that are respectively connected to the process exhaust branch pipe 10, the general exhaust branch pipe 20 and the inlet of the exhaust fan 30; a first valve plate 51 and a second valve plate 52 are rotatably disposed in the housing 50; and a driving device 53 is used to drive the first valve plate 51 and the second valve plate 52 to rotate synchronously.

[0066] The first valve plate 51 and the second valve plate 52 are configured to be fixedly connected in an L-shape, and can switch between the first working state and the second working state by being driven by the driving device 53.

[0067] Specifically, the first valve plate 51 and the second valve plate 52 are set at a fixed angle through a shared rotating shaft 59. When the first valve plate 51 rotates to open the exhaust path, the other second valve plate 52 rotates to the sealing position, thereby realizing the interlocking switching of the two passages inside the housing 50.

[0068] In the existing technology, most common air valves are single valve plate structures. If it is necessary to control the switching of multiple channels, multiple valves need to work together, which has problems such as complex control and asynchronous operation.

[0069] This application designs a valve plate structure with two L-shaped fixed connections and uses a common rotating shaft 59 for linkage drive, so that when one plate is opened, the other plate automatically closes, realizing the interlocking switching of the two air ducts under a single drive. The structure is compact, the response is fast, and the sealing is reliable.

[0070] The drive device 53 is an electric actuator or a pneumatic actuator.

[0071] Specifically, the electric actuator is an electric valve head located outside the housing 50, with its output shaft connected to the rotating shaft 59, used to receive control signals and drive the first valve plate 51 and the second valve plate 52 to rotate to a predetermined angle.

[0072] In the existing technology, some exhaust valves are driven manually or mechanically, which is inconvenient to operate and difficult to integrate with automation systems;

[0073] This application uses an electric valve actuator or pneumatic actuator as the driving mechanism, and receives the switching signal output by the controller 60 to achieve precise motion control of the first valve plate 51 and the second valve plate 52, which facilitates remote control and system linkage, and significantly improves the automation level of the exhaust system.

[0074] The air duct switching valve 40 also includes a limiting mechanism 54, which limits the rotation angle of the first valve plate 51 and the second valve plate 52 to ensure that they are accurately switched to the first working state or the second working state.

[0075] Specifically, the limiting mechanism 54 includes a limiting block 55 and a mechanical stop structure 57, which are respectively disposed on the rotating shaft 59 or the housing 50 structure, and are used to prevent the first valve plate 51 and the second valve plate 52 from rotating beyond the design angle.

[0076] In the existing technology, multi-plate linkage valves have the risk of valve plate rotation exceeding the limit, which may cause the air duct to fail to close completely or to open multiple passages by mistake, resulting in reduced exhaust efficiency or cross-contamination.

[0077] This application precisely limits the opening / closing angle of the valve plate structure by setting a limiting block 55 and a mechanical stop structure 57 on the rotating shaft 59 or the housing 50, ensuring that the first valve plate 51 and the second valve plate 52 are always in the predetermined position, effectively preventing malfunction or mechanical damage.

[0078] The air duct switching valve 40 also includes a sealing structure 56, which is disposed between the inner wall of the housing 50 and the closed edges of the first valve plate 51 and the second valve plate 52, for forming a seal when the air duct is blocked.

[0079] Specifically, the sealing structure 56 is arranged along the inner wall of the housing 50 to form a contact area with the contact surfaces of the first valve plate 51 and the second valve plate 52, and makes sealing contact with them when the first valve plate 51 and the second valve plate 52 are closed to block gas leakage.

[0080] In the prior art, poor sealing between the valve plate and the housing 50 is often caused by manufacturing errors, resulting in gas leakage and affecting the pressure stability of the clean environment;

[0081] This application provides an elastic sealing strip 58 between the inner wall of the housing 50 and the edges of the first valve plate 51 and the second valve plate 52, and forms a surface contact seal by means of compression and deformation, which improves the sealing performance when the air duct is blocked and effectively prevents airflow from passing through or cross-contamination.

[0082] Furthermore, the sealing structure 56 is an elastic sealing strip 58 disposed on the closed edge of the first valve plate 51 and the second valve plate 52 or on the inner wall of the housing 50.

[0083] Specifically, the elastic sealing strip 58 is made of EPDM rubber or silicone material and is fixed to the edge of the first valve plate 51, the second valve plate 52 or the corresponding position of the housing 50 by means of a slot, and has the ability to compress and deform to enhance the sealing effect.

[0084] In the prior art, some sealing strips have poor material versatility, are not firmly fixed, and are prone to aging and falling off. This application uses elastic sealing strips 58 made of EPDM rubber or silicone material, which are installed on the edge of the first valve plate 51, the second valve plate 52 or the sealing position of the housing 50 by means of a slot fixing method. They have good chemical corrosion resistance, high humidity resistance and reliable sealing performance, which enhances the service life and maintenance convenience of the overall device.

[0085] The first valve plate 51 and the second valve plate 52 maintain a blocking state on at least one of the process exhaust branch pipe 10 and the general exhaust branch pipe 20 at any position during their rotation stroke.

[0086] Specifically, the L-shaped structure ensures that at least one side of the first valve plate 51 and the second valve plate 52 is in contact with the air duct opening at any rotation angle, thus preventing both air ducts from being open at the same time.

[0087] In the prior art, the traditional two-ventilation-duct switching structure has the risk of opening at the same time in the middle position, which may cause gas mixing and disrupt the pressure difference in the clean area. This application, through the L-shaped valve plate structure design, ensures that at least one air duct is always sealed during the entire rotation stroke of the first valve plate 51 and the second valve plate 52, thereby avoiding the risk of simultaneous opening of air ducts from the structural nature and ensuring the stability of ventilation control in the clean room.

[0088] It also includes a controller 60, which is signal-connected to the drive device 53 of the air duct switching valve 40, and is used to control the air duct switching valve 40 to automatically switch between the first working state and the second working state according to the operating state of the process equipment.

[0089] In the prior art, most air duct switching requires manual switching or lacks linkage judgment with the operating status of process equipment, resulting in a delayed response. This application introduces an automatic controller 60, which can receive process equipment operating signals, intelligently judge and control the status of air duct switching valve 40, realize automatic linkage between equipment operation and exhaust switching, and improve the system response speed and control accuracy.

[0090] The controller 60 is also connected to a pressure sensor signal for detecting workshop pressure; the controller 60 is configured to adjust the working state of the air duct switching valve 40 according to the signal of the pressure sensor in order to maintain the pressure stability of the cleanroom.

[0091] Specifically, the controller 60 has built-in control logic that automatically controls the air duct switching valve 40 to switch to the process exhaust passage when a process equipment start signal is detected; and returns to the normal exhaust passage when the equipment is shut down.

[0092] In the prior art, differential pressure control in cleanrooms often requires an independent pressure setting system, which cannot be linked and optimized with the exhaust system. The controller 60 of this application simultaneously receives pressure sensor signals from the clean area and dynamically adjusts the valve status accordingly to ensure that the internal differential pressure of the cleanroom is stable within the set range, thereby achieving system optimization of exhaust and differential pressure control.

[0093] The housing 50 of the air duct switching valve 40 is provided with an observation window or maintenance port.

[0094] Specifically, the observation window is a transparent viewing window structure located on the side wall of the housing 50, used to manually observe the position status or internal operation of the first valve plate 51 and the second valve plate 52 without stopping the machine.

[0095] In the prior art, the air valve structure is closed and lacks a viewing window, making it inconvenient to check the valve plate status or the accumulation of internal contaminants during operation; this application sets a transparent observation window or maintenance port in the housing 50, so that maintenance personnel can observe the valve operation status in real time without stopping the machine, improving the timeliness of fault detection and maintenance efficiency.

[0096] The first valve plate 51 and the second valve plate 52 are made of corrosion-resistant materials and / or have an anti-condensation coating on their surfaces.

[0097] Specifically, the first valve plate 51 and the second valve plate 52 are made of 304 stainless steel or aluminum alloy, with a polytetrafluoroethylene anti-corrosion coating sprayed on the surface and a hydrophilic anti-condensation coating applied to adapt to the humid exhaust environment.

[0098] In the prior art, the exhaust medium often contains acids, alkalis or water vapor, which can easily corrode the valve body or cause condensation problems after long-term use, affecting the reliability of operation. This application achieves long-term adaptability to humid and corrosive gases by selecting stainless steel or aluminum alloy materials and spraying polytetrafluoroethylene and anti-condensation coating on the surface, thus extending the service life and ensuring operational stability.

[0099] The air duct switching valve 40 has a modular structure, and its housing 50, first valve plate 51, second valve plate 52 and drive device 53 are detachably connected.

[0100] In the prior art, the air valve assembly is assembled as a whole structure, which makes maintenance and replacement difficult. In this application, the housing 50, the drive device 53, the first valve plate 51 and the second valve plate 52 are designed as a detachable modular structure, which facilitates later installation, maintenance and replacement, and improves the maintainability and manufacturing versatility of the system.

[0101] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An exhaust system for a pharmaceutical cleanroom, characterized in that, include: Process exhaust branch pipes are used to connect to process equipment; Typical exhaust branch pipes are used to connect cleanroom spaces; Exhaust fan; And a duct switching valve; The process exhaust branch pipe and the general exhaust branch pipe are converged through the duct switching valve and connected to the inlet of the exhaust fan; the duct switching valve is configured to have at least two operating states: In the first working state, the passage from the process exhaust branch pipe to the exhaust fan is opened, while the general exhaust branch pipe is blocked. In the second operating state, the passage from the general exhaust branch pipe to the exhaust fan is opened, while the process exhaust branch pipe is blocked.

2. The exhaust system for pharmaceutical cleanrooms as described in claim 1, characterized in that, The duct switching valve includes a housing with interfaces respectively communicating with the process exhaust branch pipe, the general exhaust branch pipe and the exhaust fan inlet; a first valve plate and a second valve plate, which are rotatably disposed in the housing; and a driving device for driving the first valve plate and the second valve plate to rotate synchronously. The first valve plate and the second valve plate are configured to be fixedly connected in an L-shape, and can be switched between the first working state and the second working state by the drive device.

3. The exhaust system for pharmaceutical cleanrooms as described in claim 2, characterized in that, The driving device is an electric actuator or a pneumatic actuator.

4. The exhaust system for a pharmaceutical cleanroom as described in claim 2, characterized in that, The air duct switching valve also includes a limiting mechanism to limit the rotation angle of the first valve plate and the second valve plate, so as to ensure that it is accurately switched to the first working state or the second working state.

5. The exhaust system for a pharmaceutical cleanroom as described in claim 2, characterized in that, The air duct switching valve also includes a sealing structure disposed between the inner wall of the housing and the closed edges of the first valve plate and the second valve plate, for forming a seal when the air duct is blocked.

6. The exhaust system for a pharmaceutical cleanroom as described in claim 5, characterized in that, The sealing structure is an elastic sealing strip disposed on the closed edge of the first valve plate, the second valve plate, or the inner wall of the housing.

7. The exhaust system for a pharmaceutical cleanroom as described in claim 2, characterized in that, The first valve plate and the second valve plate maintain a blocking state on at least one of the process exhaust branch pipe and the general exhaust branch pipe at any position during their rotation stroke.

8. The exhaust system for a pharmaceutical cleanroom as described in claim 1, characterized in that, It also includes a controller, which is signal-connected to the drive device of the air duct switching valve, and is used to control the air duct switching valve to automatically switch between the first working state and the second working state according to the operating state of the process equipment.

9. The exhaust system for a pharmaceutical cleanroom as described in claim 8, characterized in that, The controller is also connected to a pressure sensor signal for detecting workshop pressure; the controller is configured to adjust the operating state of the air duct switching valve according to the signal from the pressure sensor in order to maintain stable pressure in the cleanroom.

10. The exhaust system for a pharmaceutical cleanroom as described in claim 2, characterized in that, The casing of the air duct switching valve is provided with an observation window or maintenance port.

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