Negative pressure vacuum pump

Abstract

The invention relates to the technical field of energy-saving vacuum pumps, in particular to a negative pressure vacuum pump which comprises a supporting assembly. The pump body comprises an air cylinder body fixed to the top of the support and a piston ring doing reciprocating motion in the air cylinder body. The air inlet assembly comprises an air inlet valve connected with the air inlet of the air cylinder body, an outer pipe fixed to the air inlet of the air inlet valve, a Venturi pipe fixed in the outer pipe and a composite filter element arranged in a Venturi pipe diverging pipe in a matched mode. By prolonging the time of gas in the composite filter element and adopting a'rough filtration-adsorption 'secondary protection system, the filtering efficiency is improved, the situation that pollutants enter the vacuum pump, friction resistance is increased, and energy consumption is increased is inhibited, and by greatly shortening the maintenance, replacement and replacement time of the gas inlet assembly, the shutdown time of the vacuum pump due to maintenance is shortened, and the service life of the vacuum pump is prolonged. And finally, the energy consumption of'starting impact current 'of restarting after shutdown and the starting probability of the standby pump are reduced, and the energy-saving effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of energy-saving vacuum pump technology, and in particular to a negative pressure vacuum pump. Background Technology

[0002] Negative pressure vacuum pumps are widely used in many fields such as industry, medicine, and laboratories. They extract gas from a closed space through mechanical or physical means to reduce the internal pressure and create a negative pressure environment. As a key component of negative pressure vacuum pumps, the air inlet filter has a crucial impact on the performance, service life, and operational stability of the vacuum pump.

[0003] Traditional negative pressure vacuum pumps use simple cylindrical shells and single filter media for their inlet filters, which typically means a sluggish filtration process. This affects the filter's efficiency and leads to poor maintenance. On the one hand, reduced filtration efficiency allows dust, oil mist, and other contaminants to enter the vacuum pump. These contaminants accumulate in the gaps between moving parts such as pistons, increasing frictional resistance and resulting in wasted electrical energy to overcome the extra friction. On the other hand, reduced efficiency and poor maintenance can lead to prolonged downtime due to maintenance, ultimately increasing the "start-up inrush current" energy consumption after restarting and the probability of using the backup pump, which is not conducive to energy conservation. This paper aims to design a new type of negative pressure vacuum pump to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above or prior art, the present invention is proposed.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a negative pressure vacuum pump, comprising,

[0007] Support components, including a bracket;

[0008] The pump body includes a cylinder body fixed to the top of a bracket, and piston rings that reciprocate inside the cylinder body.

[0009] The intake assembly comprises an intake valve connected with the intake port of the cylinder block, an outer pipe fixed on the intake port of the intake valve, a Venturi tube fixed inside the outer pipe, a composite filter element fitted inside the diverging tube of the Venturi tube, a base frame abutting against the bottom of the composite filter element, a spring abutting against the bottom of the base frame, a sealing ring abutting against the top of the composite filter element, and support rods in a ring array inserted inside the composite filter element.

[0010] The bottom of the spring abuts against the intake port of the intake valve, the bottom end of the support rod is fixed on the base frame, the top end of the support rod is fixed on the sealing ring, and the outer part of the sealing ring abuts against the joint between the diverging tube and the throat tube of the Venturi tube.

[0011] The exhaust assembly comprises an exhaust valve connected with the exhaust port of the cylinder block.

[0012] As a preferred scheme of the negative pressure vacuum pump, the support assembly further comprises protective covers fixed on both sides of the support frame and universal wheels fixed on the bottom of the support frame.

[0013] As a preferred scheme of the negative pressure vacuum pump, the pump body further comprises a piston rod fixed on the center of the piston ring and a guide frame sliding outside the piston rod, and the guide frame is fixed on the bottom port of the cylinder block.

[0014] As a preferred scheme of the negative pressure vacuum pump, the drive source further comprises a motor fixed on the support frame, a crank fixed on the drive shaft of the motor, and a connecting rod rotating on the crank, and the end of the connecting rod away from the crank is rotationally connected to the bottom end of the piston rod.

[0015] As a preferred scheme of the negative pressure vacuum pump, the composite filter element is in the shape of a frustum of a cone matching the inner cavity of the diverging tube of the Venturi tube, and the composite filter element comprises a melt-blown cloth filter element and an activated carbon filter paper filter element, wherein the activated carbon filter paper filter element is wrapped outside the melt-blown cloth filter element, the top port of the activated carbon filter paper filter element is covered by the bottom of the sealing ring, and the inner hole of the sealing ring is aligned with the top end of the melt-blown cloth filter element.

[0016] As a preferred scheme of the negative pressure vacuum pump, the exhaust assembly further comprises an aluminum alloy gas storage tank connected with the exhaust port of the exhaust valve and a pressure gauge fixed on the aluminum alloy gas storage tank, and the aluminum alloy gas storage tank is fixedly installed inside the support frame.

[0017] As a preferred scheme of the negative pressure vacuum pump, the intake valve and the exhaust valve are both of the one-way valve type.

[0018] As a preferred scheme of the negative pressure vacuum pump, the outer pipe and the Venturi tube are both made of transparent material.

[0019] The beneficial effects of the negative pressure vacuum pump of the application: through the use of the Venturi tube, the residence time of the gas in the composite filter element is prolonged, the filtering efficiency is significantly improved, the stable and efficient operation of the negative pressure vacuum pump is ensured, the melt-blown cloth and activated carbon filter paper are multi-layered, forming a "coarse filtration-adsorption" two-stage protection system, through the elastic force of the spring, the sealing ring is tightly abutted on the inner wall of the Venturi tube, facilitating the taking, placing, disassembling and replacing of the composite filter element, greatly shortening the maintenance and replacement time of the air inlet assembly. The above design can inhibit the entry of pollutants into the vacuum pump, increase the friction resistance and improve the invalid energy consumption, on the other hand, shorten the downtime of the vacuum pump due to maintenance, ultimately reduce the "start-up impact current" energy consumption after restarting and the probability of starting the standby pump, and achieve the energy-saving effect. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 It is a schematic diagram of the overall structure of the negative pressure vacuum pump.

[0022] Figure 2 It is a schematic diagram of the assembly of the cylinder body of the negative pressure vacuum pump.

[0023] Figure 3 It is a schematic diagram of the disassembly of the pump body structure of the negative pressure vacuum pump.

[0024] Figure 4 It is a schematic diagram of the air inlet assembly structure of the negative pressure vacuum pump.

[0025] Figure 5 It is a schematic diagram of the air inlet assembly structure of the negative pressure vacuum pump. Figure 4 It is a sectional view of A-A in the above.

[0026] Figure 6 It is a schematic diagram of the structure disassembly in the above. Figure 4

[0027] It is a simplified schematic diagram of the composite filter element structure. Figure 7

[0028] Figure 8 It is a schematic diagram of the assembly of the driving source of the negative pressure vacuum pump.

[0029] In the figure: 100, support assembly; 200, pump body; 300, driving source; 400, air inlet assembly; 500, exhaust assembly;

[0030] 101, bracket; 102, protective cover; 103, universal wheel;​

[0031] 201, cylinder body; 202, piston ring; 203, piston rod; 204, guide frame;

[0032] 301, motor; 302, crank; 303, connecting rod;

[0033] 401, air inlet valve; 402, outer tube; 403, Venturi tube; 404, composite filter element; 4041, melt-blown cloth filter element; 4042, activated carbon filter paper filter element; 405, chassis; 406, support rod; 407, sealing ring; 408, spring;

[0034] 501, exhaust valve; 502, aluminum alloy air tank; 503, pressure gauge. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] Reference Figures 1-8 For an embodiment of the present application, the embodiment provides a negative pressure vacuum pump, comprising a support assembly 100, which comprises a support 101, the support assembly 100 further comprises a protective cover 102 fixed on both sides of the support 101, and a universal wheel 103 fixed on the bottom of the support 101, wherein the protective cover 102 is used for protecting the equipment in operation, preventing external impact damage, and the universal wheel 103 can facilitate the transfer of the device, improving the convenience of use.

[0037] Further, referring to Figures 1-3 The negative pressure vacuum pump further comprises a pump body 200, which comprises a cylinder body 201 fixed on the top of the support 101, and a piston ring 202 reciprocating in the cylinder body 201.

[0038] In this embodiment, the working form of the vacuum pump is a reciprocating piston pump, by the piston ring 202 reciprocating in the cylinder body 201, thereby periodically changing the volume inside the cylinder body 201, achieving the effect of using negative pressure to remove air in the target when expanding the volume, and discharging the extracted gas from the cylinder body 201 when compressing the volume, thereby achieving the purpose of negative pressure vacuum.

[0039] Reference Figures 1-3The pump body 200 further comprises a piston rod 203 fixed at the center of the piston ring 202, and a guide frame 204 sliding outside the piston rod 203, the guide frame 204 being fixed at the bottom end of the cylinder body 201. In order to maintain the stability of the reciprocating movement of the piston ring 202, the direction of the piston rod 203 movement is limited by the guide frame 204, thereby reducing the wear of the piston ring 202 and the cylinder body when the piston ring 202 deviates, and improving the service life. In the embodiment, the piston ring 202 is made of oil-free self-lubricating material, and the inner surface of the cylinder body 201 has a hard layer with a hardness HV0.1>420, thereby achieving the effects of ensuring the sealing property and the service life of the product.

[0040] Further, referring to Figure 1 and Figure 8 The negative pressure vacuum pump further comprises a driving source 300, which comprises a motor 301 fixed on the bracket 101, a crank 302 fixed on the driving shaft of the motor 301, and a connecting rod 303 rotating on the crank 302, one end of the connecting rod 303 away from the crank 302 being rotationally connected to the bottom end of the piston rod 203. In the embodiment, the crank 302 and the connecting rod 303 constitute a common reciprocating driving structure form. When the motor 301 drives the crank 302 to rotate, the crank 302 drives the connecting rod 303 to make a circular motion, so that when the piston rod 203 is directionally limited by the guide frame 204, the piston ring 202 can be driven by the connecting rod 303 to make a reciprocating motion inside the cylinder body 201, thereby achieving the purpose of periodically changing the volume of the cylinder body 201.

[0041] Referring to Figures 4-6 The negative pressure vacuum pump further comprises an air inlet assembly 400, which comprises an air inlet valve 401 connected to the air inlet of the cylinder body 201, an outer pipe 402 fixed to the air inlet of the air inlet valve 401, a Venturi tube 403 fixed inside the outer pipe 402, a composite filter element 404 fitted inside the gradually expanding pipe of the Venturi tube 403, a bottom frame 405 abutting the bottom of the composite filter element 404, a spring 408 abutting the bottom of the bottom frame 405, a sealing ring 407 abutting the top of the composite filter element 404, and support rods 406 in the form of an annular array inserted inside the composite filter element 404.

[0042] The bottom of the spring 408 abuts the air inlet of the air inlet valve 401, the bottom end of the support rod 406 is fixed to the bottom frame 405, the top end of the support rod 406 is fixed to the sealing ring 407, and the outside of the sealing ring 407 abuts the junction of the gradually expanding pipe and the throat pipe of the Venturi tube 403.

[0043] In this embodiment, the composite filter element 404 is supported by a rigid structure composed of the support rod 406 and the chassis 405, so as to avoid serious deformation when being impacted by airflow, and further avoid air leakage. Further, the compression of the spring 408 by the air inlet structure of the air inlet valve 401 causes the chassis 405 to be compressed by the spring 408 towards the bottom end of the converging tube of the Venturi tube 403. The compression force is transmitted by the support rod 406, so that the sealing ring 407 is tightly abutted on the inner wall of the Venturi tube 403, thereby ensuring the air tightness between the composite filter element 404 and the Venturi tube 403, and facilitating the taking, placing, disassembling and replacing of the composite filter element 404.

[0044] It should be noted that the Venturi tube 403 is a mature existing technology. The Venturi tube 403 is composed of three structures, and the formal names of the three structures are converging tube (conical converging section), diverging tube (conical diverging section) and throat tube (cylindrical throat). In this embodiment, the converging tube (conical converging section) is located at the top inlet of the Venturi tube 403, that is, the horn tube away from the cylinder block 201. The converging tube is usually a conical tube with a cone angle of about 21°±2°. The function of the converging tube is to gradually accelerate the fluid and increase the flow rate when the fluid passes through the converging tube. According to Bernoulli's principle, the static pressure energy of the fluid is converted into kinetic energy, thereby causing the fluid pressure to decrease. The throat tube (cylindrical throat) is a short straight tube segment after the converging tube. The diameter of the throat tube is smaller than the diameter of the converging tube, and the length of the throat tube is equal to the diameter of the converging tube. The function of the throat tube is to make the flow rate of the fluid reach the maximum and the pressure reach the minimum at the throat tube. When measuring the flow rate, the flow rate of the fluid can be calculated by measuring the pressure difference between the throat tube and the inlet, combined with other parameters. The diverging tube (conical diverging section) is connected after the throat tube, that is, the horn tube close to the cylinder block 201. The diverging tube is conical, and the diffusion angle is generally 7°-15°. The function of the diverging tube is to gradually decelerate the fluid and reduce the flow rate when the fluid passes through the diverging tube. The kinetic energy is gradually converted into static pressure energy, and the fluid pressure gradually recovers, thereby reducing the turbulence and reducing the pressure head loss.

[0045] Further, the shape of the composite filter element 404 is a frustum of cone matched with the inner cavity of the diverging tube of the Venturi tube 403. The composite filter element 404 includes a melt-blown cloth filter element 4041 and an activated carbon filter paper filter element 4042. The activated carbon filter paper filter element 4042 is wrapped outside the melt-blown cloth filter element 4041. The top end of the activated carbon filter paper filter element 4042 is shielded by the bottom of the sealing ring 407, and the inner hole of the sealing ring 407 is aligned with the top end of the melt-blown cloth filter element 4041.

[0046] Referring to Figure 7, in order to facilitate understanding of the structure of the composite filter element 404, the actual reference object is combined for popularization description, in the embodiment, the composite filter element 404 can refer to the steamed dumpling food in the breakfast to understand the structure, which is composed of the outer cloth bag-shaped covering crust and the internal filling stuffing, the top end port of the covering crust is in the open state, the stuffing fills the covering crust and the top is flush with the top end opening of the covering crust, specific to the device, the activated carbon filter paper filter element 4042 is the cloth bag-shaped covering crust, the top end has an opening, the melt-blown cloth filter element 4041 is the filling stuffing, the top end is flush with the opening, the bottom end port of the sealing ring 407 is just sealed around the top end port of the activated carbon filter paper filter element 4042, the inner hole of the sealing ring 407 is aligned with the top end of the melt-blown cloth filter element 4041, that is, the top end of the melt-blown cloth filter element 4041 is exposed below the throat pipe bottom end port of the venturi tube 403 through the inner hole of the sealing ring 407, so the design makes the gas enter the throat pipe of the venturi tube 403, when flowing out, only can flow into the melt-blown cloth filter element 4041, in the embodiment, the melt-blown cloth is treated by electrostatic precipitation, the large particles are intercepted by electrostatic adsorption, the porous structure is matched to reduce the air inlet resistance, so that the vacuum extraction is more smooth; the activated carbon filter paper filter element 4042 is composed of coconut shell activated carbon impregnated filter paper, through the accurate grammage and pore size distribution design, the air inlet resistance increment is effectively controlled under the premise of ensuring the adsorption capacity, it is a major improvement on the performance of the traditional activated carbon filter element.

[0047] In this embodiment, the outer tube 402 is connected to the target for conduction. When the pump body 200 generates negative pressure in the above-mentioned communication pipeline, the gas in the target will be "pumped" into the gas inlet assembly 400 under the gas pressure. The gas will pass through the converging tube, the throat tube and the diverging tube of the Venturi tube 403 in turn. According to the above description, the converging tube of the Venturi tube 403 gradually accelerates the entering gas, and the flow rate increases. According to Bernoulli's principle, the static pressure energy is converted into kinetic energy, and the pressure is reduced. This characteristic can be used to preliminarily separate larger particulate impurities in the gas, so that they are more easily intercepted under the action of inertia. The flow rate of the gas is the largest and the pressure is the smallest at the throat tube, which can enhance the adsorption force of the fine impurities, and at the same time, a small amount of purification medium can be mixed with the gas to improve the preliminary purification effect, and it is also convenient for subsequent more accurate measurement of gas flow to master the filtration situation (here, a bypass pipeline needs to be connected to the side of the throat tube to form a three-way pipe, which is a common technology for using the Venturi tube 403, and will not be described here). The diverging tube gradually decelerates the gas, and the kinetic energy is converted into static pressure energy, and the pressure gradually recovers, reducing the turbulence and pressure head loss, so that the gas passes through the composite filter element 404 smoothly, prolonging the service life of the filter material, and enabling the gas to fully contact the filter material during the flow rate slowing process, thereby improving the filtration efficiency, and ultimately providing a cleaner gas inlet for the vacuum pump, reducing the wear and damage of impurities to the pump body. Through the use of the Venturi tube 403, the residence time of the gas in the composite filter element 404 is extended from the conventional 0.1s to 0.3s, significantly improving the adsorption efficiency of harmful gases. Through the above design, the composite filter element 404 realizes the multiple functions of flow rate regulation, particle filtration and adsorption enhancement, ensuring the stable and efficient operation of the negative pressure vacuum pump.

[0048] Referring to Figure 1 The negative pressure vacuum pump further comprises an exhaust assembly 500, which comprises an exhaust valve 501 connected with an exhaust port of the cylinder block 201.

[0049] The exhaust assembly 500 further comprises an aluminum alloy gas storage tank 502 connected with the exhaust outlet of the exhaust valve 501, and a pressure gauge 503 fixed on the aluminum alloy gas storage tank 502. The aluminum alloy gas storage tank 502 is fixedly installed in the interior of the support 101. The extracted gas is temporarily stored in the aluminum alloy gas storage tank 502, which can avoid leakage of harmful gas and cause secondary pollution on the one hand, and the high-pressure gas stored in the aluminum alloy gas storage tank 502 can also be used as a gas source for pneumatic equipment under safe conditions, thereby achieving energy reuse and realizing the purpose of energy saving.

[0050] In this embodiment, the intake valve 401 and the exhaust valve 501 are both one-way valves, and it is obvious that the intake valve 401 can only allow gas to flow into the inside of the cylinder block 201, and the exhaust valve 501 can only allow gas to flow out of the inside of the cylinder block 201, and it should be noted that the vacuum pump needs to maintain a high vacuum degree, and the sealing requirement will be very high, and in specific use, the device should select appropriate types of one-way valves to meet different air tightness requirements, for example, if a valve plate type one-way valve is used, at this time, the sealing of the valve plate and the valve plate of the intake and exhaust valve is very important, and the valve plate should use high-precision grinding process, and the valve plate should also be polished for 72 hours to achieve reliable air tightness.

[0051] Further, in order to improve the use convenience of the device, the intake filter, that is, the intake assembly 400 can adopt a transparent shell, so that the use state of the composite filter element 404 can be directly observed, and the effect of cleaning or replacing the composite filter element 404 in time can be achieved, at this time, the outer pipe 402 and the venturi tube 403 should be made of transparent materials, and in this embodiment, both can be made of high-transmittance, high-strength polycarbonate PC, acrylic PMMA or polypropylene PP, polyvinylidene fluoride PVDF materials, wherein when the thickness of both is greater than or equal to 5 mm, the radial pressure under a negative pressure environment of 0.15 MPa can be withstood, and at the same time, it is convenient for the operator to observe the pollution state of the composite filter element 404 from the outside 360°, and in implementation, observation marks can also be printed on the outer pipe 402, for example, three-color warning rings, green, yellow and red, are printed on the surface of the outer pipe 402, which correspond to filter cleanliness levels respectively, for example, green: differential pressure <100 Pa, normal; yellow: 100 Pa≤differential pressure <300 Pa, need to be cleaned; red: differential pressure ≥300 Pa, forced replacement, and a built-in LED ring lamp in the outer pipe 402 is matched, white constant, yellow flashing, red constant, so as to realize visual state early warning, of course, the above is only a relatively simple convenience measure that can be realized in implementation, and more accurate monitoring can also be realized through various sensors and visual devices, which all belong to the prior art and will not be described here.

[0052] In this embodiment, by improving the filtering efficiency, dust, oil mist and other pollutants can be effectively blocked from entering the inside of the pump, on the one hand, the problem of increased friction resistance caused by the accumulation of pollutants in the gap between the piston ring 202 and other moving parts can be reduced, and the pump body 200 can avoid consuming invalid electric energy to overcome the additional friction, so as to realize "resistance reduction and energy saving"; on the other hand, the inside air duct can be prevented from being blocked by pollutants, so as to ensure that the pumping efficiency is always at the designed peak value, and the low energy consumption caused by the need to prolong the running time due to the decrease of the pumping efficiency can be avoided, so as to achieve "efficiency improvement and energy saving".

[0053] In addition, by connecting the air inlet valve 401 to the air inlet structure, the compression of the spring 408 is facilitated, and the sealing ring 407 is tightly abutted on the inner wall of the Venturi tube 403 by the elastic force of the spring 408, thereby ensuring the air tightness between the composite filter element 404 and the Venturi tube 403, facilitating the taking, placing, disassembling and replacing of the composite filter element 404, greatly shortening the maintenance and replacement time of the air inlet assembly 400, reducing the long downtime of the vacuum pump due to maintenance, reducing the "start-up surge current" energy consumption after restarting and the probability of starting the standby pump, ultimately reducing the downtime / start-stop energy consumption, maintaining the optimal operating state of the vacuum pump with low resistance and low power consumption for a long time, and achieving the energy-saving goal of reducing the total power consumption.

[0054] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A negative pressure vacuum pump, characterized in that: include, Support assembly (100), which includes bracket (101); The pump body (200) includes a cylinder body (201) fixed to the top of the bracket (101) and a piston ring (202) reciprocating inside the cylinder body (201); The intake assembly (400) includes an intake valve (401) connected to the intake port of the cylinder block (201), an outer tube (402) fixed to the intake port of the intake valve (401), a venturi tube (403) fixed inside the outer tube (402), a composite filter element (404) fitted inside the venturi tube (403) diffuser, a base frame (405) abutting the bottom of the composite filter element (404), a spring (408) abutting the bottom of the base frame (405), a sealing ring (407) abutting the top of the composite filter element (404), and support rods (406) arranged in a ring array and inserted inside the composite filter element (404). The bottom of the spring (408) abuts against the air inlet of the intake valve (401), the bottom end of the support rod (406) is fixed to the base frame (405), the top end of the support rod (406) is fixed to the sealing ring (407), and the outside of the sealing ring (407) abuts against the junction of the diffuser and the throat of the venturi tube (403); and An exhaust assembly (500) includes an exhaust valve (501) connected to an exhaust port of the cylinder block (201).

2. The negative pressure vacuum pump as described in claim 1, characterized in that: The support assembly (100) also includes protective covers (102) fixed to both sides of the bracket (101) and casters (103) fixed to the bottom of the bracket (101).

3. The negative pressure vacuum pump as described in claim 2, characterized in that: The pump body (200) also includes a piston rod (203) fixed to the center of the piston ring (202) and a guide frame (204) sliding outside the piston rod (203), the guide frame (204) being fixed to the bottom port of the cylinder body (201).

4. The negative pressure vacuum pump as described in claim 3, characterized in that: It also includes a drive source (300), which includes a motor (301) fixed on a bracket (101), a crank (302) fixed on the drive shaft of the motor (301), and a connecting rod (303) rotating on the crank (302), with one end of the connecting rod (303) away from the crank (302) rotatably connected to the bottom end of the piston rod (203).

5. The negative pressure vacuum pump as described in claim 4, characterized in that: The composite filter element (404) is shaped like a frustum to match the inner cavity of the venturi tube (403). The composite filter element (404) includes a meltblown cloth filter element (4041) and an activated carbon filter paper filter element (4042). The activated carbon filter paper filter element (4042) covers the outside of the meltblown cloth filter element (4041). The top port of the activated carbon filter paper filter element (4042) is covered by the bottom of the sealing ring (407), and the inner hole of the sealing ring (407) is aligned with the top of the meltblown cloth filter element (4041).

6. The negative pressure vacuum pump as described in claim 5, characterized in that: The exhaust assembly (500) also includes an aluminum alloy gas tank (502) connected to the outlet of the exhaust valve (501) and a pressure gauge (503) fixed on the aluminum alloy gas tank (502), which is fixedly installed inside the bracket (101).

7. The negative pressure vacuum pump as described in claim 6, characterized in that: Both the intake valve (401) and the exhaust valve (501) are one-way valves.

8. The negative pressure vacuum pump as described in claim 7, characterized in that: Both the outer tube (402) and the venturi tube (403) are made of transparent material.

Images