Bacterial filter and vacuum negative pressure unit

Abstract

The application relates to the technical field of vacuum negative pressure unit, in particular to a bacteria filter and a vacuum negative pressure unit. The bacteria filter comprises a cylinder, an air inlet pipe, an air outlet pipe, a first cylindrical filter core, a second cylindrical filter core, a plugging head and an axial moving assembly. When the second cylindrical filter core is located at a first position, the second cylindrical filter core and the first cylindrical filter core overlap in the axial direction, and the plugging head plugs the lower end opening of the first cylindrical filter core. When the second cylindrical filter core is located at a second position, the second cylindrical filter core and the first cylindrical filter core are staggered in the axial direction, and the plugging head is separated from the lower end opening of the first cylindrical filter core. Through the cooperation of the first cylindrical filter core, the second cylindrical filter core, the plugging head and the axial moving assembly, when the suction amount is small, the filtering path can be prolonged, and the filtering effect is improved. When the suction amount is large, the filtering path can be shortened, and the passing efficiency of the suction gas is improved.

Description

Technical Field

[0001] This invention relates to the field of vacuum negative pressure unit technology, specifically to a bacterial filter and a vacuum negative pressure unit. Background Technology

[0002] Medical vacuum negative pressure units are an important component of hospital negative pressure suction systems, typically including components such as vacuum pumps and vacuum tanks. The vacuum pump draws gas from the tubing, creating a negative pressure environment in the vacuum tank, and then provides negative pressure suction conditions to the terminal via a piping network. Because the suctioned gas may carry bacteria, microorganisms, or other contaminants, a bacterial filter is usually installed in the suction tubing of the medical vacuum negative pressure unit to filter the suctioned gas and prevent contaminants from entering the vacuum pump and subsequent exhaust tubing.

[0003] Existing bacterial filters mainly consist of a cylinder, an inlet pipe, an outlet pipe, and a filter element installed inside the cylinder. During operation, under the negative pressure generated by the vacuum pump, gas is drawn in through the inlet pipe and enters the filter element. Under the pressure difference, the gas passes through the filter element, and finally, the filtered gas is discharged through the outlet pipe.

[0004] To ensure filtration accuracy, existing filters typically extend the filtration path to increase the contact time between the gas and the filter element, thereby enhancing the retention of bacteria and microorganisms. However, in actual operation, the negative pressure suction demand at the terminal of a vacuum negative pressure unit often changes. When the suction volume is small, a longer filtration path allows for more thorough filtration of the suction gas; but when the suction volume suddenly increases, the suction gas still needs to pass through the filter element along a longer path, which can easily increase gas flow resistance, reduce gas throughput, and thus affect the continuity and stability of the terminal negative pressure suction. Therefore, we propose a bacterial filter and a vacuum negative pressure unit to effectively address these shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a bacterial filter and a vacuum negative pressure unit to solve the problem mentioned in the background art that the bacterial filter adopts a fixed filtration path and is difficult to adapt to usage scenarios with large fluctuations in suction volume.

[0006] This invention is achieved through the following technical solution: a bacterial filter, comprising a cylinder, an inlet pipe, and an outlet pipe, and further comprising: The first cylindrical filter element is disposed inside the cylinder. The upper end of the first cylindrical filter element is connected to the air inlet pipe, and the lower end of the first cylindrical filter element is open. The second cylindrical filter element is coaxially sleeved on the outer periphery of the first cylindrical filter element; a ventilation cavity is formed between the second cylindrical filter element and the cylindrical body, and the ventilation cavity is connected to the air outlet pipe. A plugging head is fixed to the inner bottom of the second cylindrical filter element, and the plugging head is adapted to the lower opening of the first cylindrical filter element; An axial movement assembly is disposed inside the cylinder and its actuating end is connected to the second cylindrical filter element, for driving the second cylindrical filter element to move along its own axial direction between a first position and a second position; When the second cylindrical filter element is in the first position, the second cylindrical filter element and the first cylindrical filter element overlap each other in the axial direction, and the sealing head seals the lower opening of the first cylindrical filter element; When the second cylindrical filter element is in the second position, the second cylindrical filter element and the first cylindrical filter element are axially offset from each other, and the sealing head is disengaged from the lower end opening of the first cylindrical filter element.

[0007] In one embodiment, the first cylindrical filter element has a first air inlet hole on the upper part of its inner wall and a first exhaust hole on the lower part of its outer wall; the second cylindrical filter element has a second air inlet hole on the lower part of its inner wall and a second exhaust hole on the upper part of its outer wall.

[0008] In one embodiment, when the second cylindrical filter element is in the first position, the first exhaust port is aligned with the second air inlet port so that the drawn gas is filtered sequentially through the first cylindrical filter element and the second cylindrical filter element; when the second cylindrical filter element is in the second position, the inner peripheral wall of the second cylindrical filter element blocks the first exhaust port so that the drawn gas directly enters the second cylindrical filter element for filtration.

[0009] In one embodiment, the axial movement assembly includes a linear drive structure and a sleeve; the linear drive structure is disposed inside the cylinder, the actuating end of the linear drive structure is connected to the sleeve, and the second cylindrical filter element is disposed inside the sleeve.

[0010] In one embodiment, the second cylindrical filter element is rotatably connected to the inside of the sleeve, and a linkage rotating structure is provided between the second cylindrical filter element and the first cylindrical filter element. The linkage rotating structure is used to make the second cylindrical filter element rotate around its own axis when it moves axially.

[0011] In one embodiment, the inner wall of the second cylindrical filter element is provided with a plurality of vent holes, and the outer wall of the second cylindrical filter element is provided with a plurality of exhaust holes; an exhaust port corresponding to each exhaust hole is provided on the side wall of the sleeve.

[0012] In one embodiment, when the second cylindrical filter element is in the first position, the air outlet is offset from the air outlet hole, and the drawn gas flows along the axial direction of the second cylindrical filter element; when the second cylindrical filter element is in the second position, the linkage rotating structure drives the second cylindrical filter element to rotate around its own axis so that the air outlet is aligned with the air outlet hole, and the drawn gas flows along the radial direction of the second cylindrical filter element.

[0013] In one embodiment, the linkage rotating structure includes a guide pin and a guide groove; the guide pin is disposed on the upper part of the inner sidewall of the second cylindrical filter element; the guide groove is disposed on the outer peripheral wall of the first cylindrical filter element, and the guide pin slides in the guide groove; the guide groove includes a straight segment and a spiral segment that are sequentially connected along the axial direction of the first cylindrical filter element.

[0014] In one embodiment, when the second cylindrical filter element is in the first position, the guide pin is located at the upper part of the straight section, at which time the first exhaust port and the second air inlet port are aligned with each other, and the exhaust port and the outlet port are offset from each other; when the second cylindrical filter element is in the third position between the first position and the second position, the guide pin is located at the lower part of the straight section, at which time the first exhaust port and the second air inlet port are offset from each other, and the exhaust port and the outlet port are offset from each other; when the second cylindrical filter element is in the second position, the guide pin is located in the spiral section, at which time the first exhaust port and the second air inlet port are offset from each other, and the exhaust port and the outlet port are aligned with each other.

[0015] The present invention also provides a vacuum negative pressure unit, including the bacterial filter described above.

[0016] Compared with the prior art, the present invention provides a bacterial filter and a vacuum negative pressure unit, which have the following beneficial effects: 1. The present invention, through the cooperation of the first cylindrical filter element, the second cylindrical filter element, the sealing head and the axial moving component, can switch the filtration path according to different suction volumes; when the suction volume is small, the filtration path can be extended to improve the filtration effect; when the suction volume is large, the filtration path can be shortened to improve the passage efficiency of the suction gas. 2. By providing a first air inlet, a first air outlet, a second air inlet, and a second air outlet, the present invention enables the gas to pass through the first cylindrical filter element in an upward-inward and downward-outward manner when the suction volume is small, and to pass through the second cylindrical filter element in a downward-inward and upward-outward manner, thereby further extending the flow path of the gas in the filter element, which is beneficial to improving the filtration effect of bacteria, microorganisms, and fine particulate matter. 3. The present invention, through the cooperation between the sleeve, the linkage rotating structure, the vent hole, the air outlet hole and the air outlet port, enables the gas to pass directly through the second cylindrical filter element in a radial flow manner from the inside to the outside when the suction volume is large, thereby further improving the air circulation efficiency of the filter element. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the filter element of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 2 Enlarged view of point B in the middle; Figure 5 This is a schematic diagram of the sleeve of the present invention; Figure 6 This is a schematic diagram of the first cylindrical filter element of the present invention; Figure 7 This is a schematic diagram of the second cylindrical filter element of the present invention; Figure 8 This is a schematic diagram of the gas flow path when the suction volume is small according to the present invention. Figure 9 This is a schematic diagram of the gas flow path when the suction volume is large according to the present invention.

[0018] In the diagram: 1. Cylinder body; 2. Inlet pipe; 3. Outlet pipe; 4. First cylindrical filter element; 5. Second cylindrical filter element; 6. Sealing head; 7. Axial movement assembly; 701. Linear drive structure; 702. Sleeve; 8. First inlet hole; 9. First exhaust hole; 10. Second inlet hole; 11. Second exhaust hole; 12. Vent hole; 13. Outlet hole; 14. Outlet; 15. Guide pin; 16. Guide groove. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figures 1 to 9 A bacterial filter includes a cylinder 1, an air inlet pipe 2, an air outlet pipe 3, a first cylindrical filter element 4, a second cylindrical filter element 5, a sealing head 6, and an axially moving assembly 7.

[0021] The first cylindrical filter element 4 is disposed inside the cylinder 1. The upper end of the first cylindrical filter element 4 is connected to the air inlet pipe 2, and the lower end of the first cylindrical filter element 4 has an opening. The second cylindrical filter element 5 is coaxially sleeved on the outer periphery of the first cylindrical filter element 4; a ventilation cavity is formed between the second cylindrical filter element 5 and the cylinder 1, and the ventilation cavity is connected to the air outlet pipe 3. The sealing head 6 is fixed to the inner bottom of the second cylindrical filter element 5, and the sealing head 6 is adapted to the lower opening of the first cylindrical filter element 4 to change the flow path of the drawn gas under different operating conditions.

[0022] In addition, the axial moving component 7 is disposed inside the cylinder 1 and its actuating end is connected to the second cylindrical filter element 5, which is used to drive the second cylindrical filter element 5 to move along its own axial direction between the first position and the second position, so that the second cylindrical filter element 5 can overlap or stagger with the first cylindrical filter element 4 in the axial direction.

[0023] Specifically, when the second cylindrical filter element 5 is in the first position, the second cylindrical filter element 5 and the first cylindrical filter element 4 overlap each other in the axial direction, and the sealing head 6 seals the lower opening of the first cylindrical filter element 4; at this time, the gas drawn into the first cylindrical filter element 4 through the air inlet pipe 2 needs to be filtered by the first cylindrical filter element 4 first, then further filtered by the second cylindrical filter element 5, and finally enters the ventilation chamber and is discharged through the air outlet pipe 3.

[0024] In this state, the drawn gas passes through the first cylindrical filter element 4 and the second cylindrical filter element 5 in sequence to achieve double-layer series filtration. The overall filtration path is longer, and the contact process between the gas and the filter material is more thorough. Therefore, it is more suitable for working conditions with small suction volume or high filtration accuracy requirements.

[0025] When the second cylindrical filter element 5 is in the second position, the second cylindrical filter element 5 and the first cylindrical filter element 4 are axially offset from each other, and the sealing head 6 is disengaged from the lower opening of the first cylindrical filter element 4. At this time, the suction gas that enters the first cylindrical filter element 4 through the air inlet pipe 2 can directly enter the inner cavity of the second cylindrical filter element 5 through the lower opening of the first cylindrical filter element 4, and then enter the ventilation chamber after being filtered by the second cylindrical filter element 5, and is discharged through the air outlet pipe 3.

[0026] In this state, the gas being drawn in can directly enter the second cylindrical filter element 5 for filtration. The filtration path is significantly shortened, the gas flow resistance is reduced, and the gas flow efficiency is improved. Therefore, it is more suitable for working conditions with large gas volume or high ventilation requirements.

[0027] In one embodiment, the first cylindrical filter element 4 and the second cylindrical filter element 5 may use the same filter material, and the inner and outer sidewalls of the first cylindrical filter element 4 and the second cylindrical filter element 5 are both breathable structures, so that the drawn gas can pass through the filter element radially from the inside to the outside.

[0028] When the suction volume is small, the first cylindrical filter element 4 and the second cylindrical filter element 5 overlap each other axially. The suction gas first passes through the first cylindrical filter element 4 from the inside to the outside, and then passes through the second cylindrical filter element 5 from the inside to the outside. Since the gas needs to pass through two layers of filter elements continuously, the overall filtration path is longer, and the contact between the gas and the filter media is more sufficient, which is beneficial to improving the bacterial filtration effect.

[0029] When the suction volume is large, the first cylindrical filter element 4 and the second cylindrical filter element 5 are axially offset from each other, and the sealing head 6 is disengaged from the lower opening of the first cylindrical filter element 4, so that the inner cavity of the first cylindrical filter element 4 and the inner cavity of the second cylindrical filter element 5 are directly connected; at this time, the suction gas can pass through the first cylindrical filter element 4 and the second cylindrical filter element 5 from the inside to the outside, that is, the first cylindrical filter element 4 and the second cylindrical filter element 5 both participate in the filtration work when they are axially offset.

[0030] Compared to the axially overlapping state, the staggered arrangement of the two filter elements creates a larger filtration range in the axial direction, increasing the actual flow area of ​​the drawn gas. This helps reduce gas flow resistance and improve the flow efficiency of the drawn gas. Furthermore, since the first cylindrical filter element 4 and the second cylindrical filter element 5 use the same filter material, their filtration performance is more consistent.

[0031] In another embodiment of this application, the first cylindrical filter element 4 can be used for coarse filtration and the second cylindrical filter element 5 can be used for fine filtration; in other embodiments, both can also use the same grade of filter media.

[0032] In this embodiment, a first air inlet 8 is provided on the upper part of the inner wall of the first cylindrical filter element 4, and a first exhaust 9 is provided on the lower part of the outer wall of the first cylindrical filter element 4. Filter media is detachably disposed in the wall of the first cylindrical filter element 4. When the gas is drawn through the first cylindrical filter element 4, it passes through the filter media in an upward-inward-outward manner.

[0033] The second cylindrical filter element 5 has a second air inlet 10 on the lower part of its inner wall and a second exhaust 11 on the upper part of its outer wall. Filter media is detachably installed in the wall of the second cylindrical filter element 5. When gas is drawn through the second cylindrical filter element 5, it passes through the filter media in a bottom-in, top-out manner.

[0034] When the second cylindrical filter element 5 is in the first position, the first exhaust port 9 is aligned with the second air inlet port 10, so that the drawn-in gas is filtered sequentially through the first cylindrical filter element 4 and the second cylindrical filter element 5. At this time, the drawn-in gas first enters the filter material area of ​​the first cylindrical filter element 4 through the first air inlet port 8, passing through the first cylindrical filter element 4 in an upward-inward-outward manner; then it enters the second air inlet port 10 through the first exhaust port 9, and then enters the filter material area of ​​the second cylindrical filter element 5, passing through the second cylindrical filter element 5 in a downward-inward-outward manner, and finally exits into the ventilation chamber through the second exhaust port 11. Figure 8 As shown.

[0035] In this path, the gas is first drawn in from the top and then out from the bottom, and then in from the bottom and out from the top, thus forming a more tortuous filtration path. This allows for more thorough contact between the gas and the filter material, which is beneficial for improving the filtration effect on bacteria.

[0036] When the second cylindrical filter element 5 is in the second position, it moves axially downward and is offset from the first cylindrical filter element 4. The inner circumferential wall of the second cylindrical filter element 5 blocks the first exhaust hole 9, thereby preventing the drawn-in gas from being discharged from the filter material area of ​​the first cylindrical filter element 4, so that the drawn-in gas can directly enter the second cylindrical filter element 5 for filtration. At this time, after the drawn-in gas enters the inner cavity of the first cylindrical filter element 4 through the air inlet pipe 2, it directly enters the interior of the second cylindrical filter element 5 through the lower opening of the first cylindrical filter element 4, and is then discharged after being filtered by the second cylindrical filter element 5.

[0037] In this path, the gas is directly drawn into the second cylindrical filter element 5, and filtration is completed using a shorter flow path, which can effectively reduce flow resistance and improve the flow efficiency of the gas.

[0038] In this embodiment, the axial movement component 7 includes a linear drive structure 701 and a sleeve 702. The linear drive structure 701 is disposed inside the cylinder 1, and its actuating end is connected to the sleeve 702. The second cylindrical filter element 5 is disposed inside the sleeve 702. In use, the linear drive structure 701 drives the sleeve 702 to move linearly along the axial direction, and the sleeve 702 then drives the second cylindrical filter element 5 to switch between a first position and a second position.

[0039] It should be added that the linear drive structure 701 can be a linear motor, cylinder, electric push rod, lead screw drive mechanism, manual push-pull mechanism, slider guide rail mechanism, or other drive structures that can realize the axial displacement of the second cylindrical filter element 5.

[0040] During the research and development process, it was found that, after adopting the above implementation method, when the suction volume is large, although the second cylindrical filter element 5 can be axially offset from the first cylindrical filter element 4, and the suction gas can be directly filtered into the second cylindrical filter element 5 by blocking the first exhaust hole 9, thereby shortening the filtration path, the suction gas still flows in the second cylindrical filter element 5 in a bottom-in, top-out manner, and the gas mainly enters the filter material area through a limited number of pores. Under the condition of large suction volume, it may still limit the passage efficiency of the suction gas, making it difficult to meet the requirements of large flow suction.

[0041] Therefore, the following design is proposed: The second cylindrical filter element 5 is rotatably connected to the inside of the sleeve 702. A linkage rotating structure is provided between the second cylindrical filter element 5 and the first cylindrical filter element 4. The linkage rotating structure is used to make the second cylindrical filter element 5 rotate around its own axis when moving along the axial direction.

[0042] The inner wall of the second cylindrical filter element 5 is provided with several rows of air holes 12, and the outer wall of the second cylindrical filter element 5 is provided with several exhaust holes 13; an air outlet 14 corresponding to each exhaust hole 13 is provided on the side wall of the sleeve 702.

[0043] Specifically, when the second cylindrical filter element 5 is in the first position, the air outlet 14 and the air outlet 13 are offset, and the suction gas flows along the axial direction of the second cylindrical filter element 5. Specifically, the suction gas first enters the filter material area of ​​the first cylindrical filter element 4 through the first air inlet 8, and passes through the first cylindrical filter element 4 in an upward-inward-outward manner. Subsequently, the suction gas enters the second air inlet 10 through the first exhaust port 9, then enters the filter material area of ​​the second cylindrical filter element 5, and passes through the second cylindrical filter element 5 in a downward-inward-outward manner, finally being discharged into the ventilation chamber through the second exhaust port 11. Figure 8 As shown.

[0044] Under this operating condition, the flow path is longer and the flow process is more tortuous, resulting in more thorough contact between the gas and the filter media, which is beneficial for improving the filtration effect on bacteria, microorganisms and fine particulate matter.

[0045] When the second cylindrical filter element 5 is in the second position, the linkage rotating structure drives the second cylindrical filter element 5 to rotate around its own axis, so that the air outlet 14 is aligned with the air outlet 13, and the sucked gas flows radially along the second cylindrical filter element 5; specifically, after the sucked gas enters the inner cavity of the first cylindrical filter element 4 through the air inlet pipe 2, it directly enters the interior of the second cylindrical filter element 5 through the lower end opening of the first cylindrical filter element 4, and enters its filter material area through the vent 12, then passes radially through the filter material from the inside to the outside, and is discharged through the air outlet 13 and the air outlet 14, as shown. Figure 9 As shown.

[0046] Under this condition, the gas being drawn in mainly completes filtration by radial flow within the second cylindrical filter element 5. This path is shorter and more direct, resulting in smoother gas flow within the second cylindrical filter element 5. Furthermore, the several rows of vent holes 12 on the inner wall of the second cylindrical filter element 5 provide more channels for the gas to enter the filter material area, thereby further improving the gas flow efficiency and ensuring the continuity and stability of the terminal negative pressure suction.

[0047] The following is an introduction to the linkage rotary structure: The linkage rotating structure includes a guide pin 15 and a guide groove 16; the guide pin 15 is disposed on the upper part of the inner side wall of the second cylindrical filter element 5; the guide groove 16 is disposed on the outer peripheral wall of the first cylindrical filter element 4, and the guide pin 15 slides in the guide groove 16. Through the guiding cooperation between the guide pin 15 and the guide groove 16, the second cylindrical filter element 5 can rotate when moving axially.

[0048] Specifically, the guide groove 16 includes a straight section and a spiral section that are sequentially connected along the axial direction of the first cylindrical filter element 4.

[0049] When the second cylindrical filter element 5 is in the first position, the guide pin 15 is located at the upper part of the straight section. At this time, the first exhaust hole 9 and the second air inlet 10 are aligned with each other, and the air outlet 13 and the air outlet 14 are staggered. The gas can be drawn through the first cylindrical filter element 4 and the second cylindrical filter element 5 in sequence by axial flow, and can pass through two layers of filtration. When the second cylindrical filter element 5 is located in the third position between the first position and the second position, the guide pin 15 is located at the lower part of the straight section. At this time, the first exhaust hole 9 and the second air inlet hole 10 are staggered, and the air outlet hole 13 and the air outlet 14 are staggered. The suction gas can pass through the second cylindrical filter element 5 in an axial flow manner and only pass through one layer of filtration. When the second cylindrical filter element 5 is in the second position, the guide pin 15 is located in the spiral section. At this time, the first exhaust hole 9 and the second air inlet hole 10 are staggered, and the air outlet 13 and the air outlet 14 are aligned with each other. The drawn gas can pass through the second cylindrical filter element 5 in a radial flow manner and only pass through one layer of filtration.

[0050] In other words, with the above structure, the bacterial filter has three working states in actual use: State 1: The second cylindrical filter element 5 is located in the first position. At this time, the guide pin 15 is located in the straight section of the guide groove 16. The second cylindrical filter element 5 and the first cylindrical filter element 4 overlap each other in the axial direction, and the air outlet 13 and the air outlet 14 are staggered.

[0051] In this state, the gas is drawn in using a double-layer filtration + axial flow method. That is, the gas is drawn in from the top and out from the bottom, or from the bottom and out from the top, and is filtered sequentially through the first cylindrical filter element 4 and the second cylindrical filter element 5. This makes the overall flow path of the gas drawn in longer and the filtration process more thorough. It is suitable for working conditions with small drawing volume and high filtration accuracy requirements.

[0052] State 2: The second cylindrical filter element 5 moves downward a certain distance from the first position until it blocks the first exhaust port 9, at which point it is in the third position. At this time, the guide pin 15 is still within the straight section, and the second cylindrical filter element 5 has not yet rotated, so the exhaust port 13 and the exhaust outlet 14 are still misaligned. At this time, the sucked gas directly enters the interior of the second cylindrical filter element 5 and continues to be filtered in the second cylindrical filter element 5 using a bottom-in, top-out method.

[0053] In this state, the gas is drawn in using a single-layer filtration + axial flow method, which shortens the filtration path and reduces the flow resistance, making it suitable for medium-volume drawing conditions.

[0054] In state three, the second cylindrical filter element 5 continues to move downwards until the second position. During this process, the guide pin 15 enters the spiral section of the guide groove 16 and drives the second cylindrical filter element 5 to rotate, aligning the air outlet 13 with the air outlet 14. At this time, the sucked gas directly enters the interior of the second cylindrical filter element 5 and passes through the filter material radially from the inside to the outside to complete the filtration.

[0055] In this state, the gas is drawn in using a single-layer filtration + radial flow method, which further shortens the gas flow path in the second cylindrical filter element 5, makes the flow direction more direct, and is more suitable for working conditions with a large suction volume.

[0056] With the above-mentioned linkage design, there is no need to set a separate drive source for the rotation of the second cylindrical filter element 5. A single axial drive combined with the guide structure can realize multi-stage state switching. Moreover, a forced timing linkage relationship is formed between the axial movement of the second cylindrical filter element 5 and its own rotation, thus avoiding the coordination and control problem between multiple drive sources and improving the consistency and stability of the overall action.

[0057] Example 2: This example also proposes a vacuum negative pressure unit, including the bacterial filter of Example 1.

[0058] Because this vacuum negative pressure unit uses the bacterial filter from Example 1, it can switch between different filtration states and gas flow patterns according to different suction requirements. Specifically: When the suction volume is small, a double-layer filtration + axial flow method is adopted, that is, the suction gas is filtered by passing through the first cylindrical filter element 4 and the second cylindrical filter element 5 in sequence in an axial flow manner, which helps to improve the filtration effect. When the suction volume is moderate, a single-layer filtration + axial flow method is adopted. That is, the suction gas no longer passes through the first cylindrical filter element 4, but directly enters the second cylindrical filter element 5 for axial flow filtration, which improves the passage capacity of the suction gas while ensuring a certain filtration effect. When the suction volume is large, a single-layer filtration + radial flow method is adopted, that is, the suction gas directly enters the interior of the second cylindrical filter element 5 and passes through the filter material radially from the inside to the outside. The flow path is the shortest and the flow mode is the most direct, which helps to improve the negative pressure suction efficiency.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bacterial filter, comprising a cylindrical body, an inlet pipe, and an outlet pipe, characterized in that, Also includes: The first cylindrical filter element is disposed inside the cylinder. The upper end of the first cylindrical filter element is connected to the air inlet pipe, and the lower end of the first cylindrical filter element is open. The second cylindrical filter element is coaxially sleeved on the outer periphery of the first cylindrical filter element; a ventilation cavity is formed between the second cylindrical filter element and the cylindrical body, and the ventilation cavity is connected to the air outlet pipe. A plugging head is fixed to the inner bottom of the second cylindrical filter element, and the plugging head is adapted to the lower opening of the first cylindrical filter element; An axial movement assembly is disposed inside the cylinder and its actuating end is connected to the second cylindrical filter element, for driving the second cylindrical filter element to move along its own axial direction between a first position and a second position; When the second cylindrical filter element is in the first position, the second cylindrical filter element and the first cylindrical filter element overlap each other in the axial direction, and the sealing head seals the lower opening of the first cylindrical filter element; When the second cylindrical filter element is in the second position, the second cylindrical filter element and the first cylindrical filter element are axially offset from each other, and the sealing head is disengaged from the lower end opening of the first cylindrical filter element.

2. The bacterial filter according to claim 1, characterized in that: The first cylindrical filter element has a first air inlet hole on the upper part of the inner side wall and a first exhaust hole on the lower part of the outer side wall. The second cylindrical filter element has a second air inlet hole on the lower part of its inner wall and a second exhaust hole on the upper part of its outer wall.

3. The bacterial filter according to claim 2, characterized in that: When the second cylindrical filter element is in the first position, the first exhaust port is aligned with the second air inlet port so that the drawn gas is filtered sequentially through the first cylindrical filter element and the second cylindrical filter element. When the second cylindrical filter element is in the second position, the inner peripheral wall of the second cylindrical filter element blocks the first exhaust hole, so that the drawn gas can directly enter the second cylindrical filter element for filtration.

4. The bacterial filter according to claim 3, characterized in that: The axial movement assembly includes a linear drive structure and a sleeve; The linear drive structure is located inside the cylinder, and the actuator of the linear drive structure is connected to the sleeve. The second cylindrical filter element is located inside the sleeve.

5. The bacterial filter according to claim 4, characterized in that: The second cylindrical filter element is rotatably connected to the inside of the sleeve. A linkage rotating structure is provided between the second cylindrical filter element and the first cylindrical filter element. The linkage rotating structure is used to make the second cylindrical filter element rotate around its own axis when it moves axially.

6. The bacterial filter according to claim 5, characterized in that: The inner wall of the second cylindrical filter element is provided with several rows of air vents, and the outer wall of the second cylindrical filter element is provided with several air discharge vents; an air outlet corresponding to each air discharge vent is provided on the side wall of the sleeve.

7. The bacterial filter according to claim 6, characterized in that: When the second cylindrical filter element is in the first position, the air outlet and the air hole are misaligned, and the drawn gas flows along the axial direction of the second cylindrical filter element. When the second cylindrical filter element is in the second position, the linkage rotating structure drives the second cylindrical filter element to rotate around its own axis so that the air outlet is aligned with the air outlet hole, and the drawn gas flows radially along the second cylindrical filter element.

8. The bacterial filter according to claim 7, characterized in that: The linkage rotary structure includes a guide pin and a guide groove; The guide pin is disposed on the upper part of the inner side wall of the second cylindrical filter element; the guide groove is disposed on the outer peripheral wall of the first cylindrical filter element, and the guide pin slides in the guide groove; The guide groove includes a straight section and a spiral section that are sequentially connected along the axial direction of the first cylindrical filter element.

9. The bacterial filter according to claim 8, characterized in that: When the second cylindrical filter element is in the first position, the guide pin is located at the upper part of the straight section. At this time, the first exhaust hole and the second air inlet are aligned with each other, and the air outlet and the air outlet are staggered. When the second cylindrical filter element is in the third position between the first position and the second position, the guide pin is located at the lower part of the straight section. At this time, the first exhaust port and the second air inlet port are offset from each other, and the air outlet port and the air outlet are offset from each other. When the second cylindrical filter element is in the second position, the guide pin is located in the spiral section. At this time, the first exhaust port and the second air inlet port are offset from each other, and the air outlet and the air outlet are aligned with each other.

10. A vacuum negative pressure unit, characterized in that, Includes the bacterial filter as described in any one of claims 1-9.

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