Special pneumatic quantity adjusting structure for metering pump

Abstract

The utility model relates to the technical field of metering pumps, and discloses a special pneumatic quantity adjusting structure for a metering pump, which comprises an air cylinder, a piston arranged in the air cylinder, the piston is fixedly connected with one end of a push rod, a reset rod is slidably connected in the other end of the push rod, the reset rod is fixedly connected with an adjusting rod, and a positioning calibration device is arranged on the reset rod. The push rod is provided with a negative pressure cavity in a cavity used for being connected with the reset rod in a sliding mode, negative pressure is formed in the negative pressure cavity through an air pump so that inward suction force can be provided for the reset rod, a return spring is arranged on the negative pressure cavity and provides outward sliding force for the reset rod, and an electromagnet is further arranged at the position, in the negative pressure cavity, of the push rod. The reset rod is attracted in the push rod under the double attraction action of the negative pressure cavity and the electromagnet, the negative pressure cavity is communicated with the outside during power failure, the air pressure rises, the electromagnet loses the electromagnetic attraction force, the reset rod rapidly descends under the action of the return spring, and the flow of the metering pump returns to zero.

Description

Technical Field

[0001] This utility model relates to the field of metering pump technology, specifically a pneumatic regulating structure for metering pumps. Background Technology

[0002] In industrial production, precise fluid delivery is crucial. Metering pumps, as core equipment for achieving precise fluid delivery, are widely used in various industries such as chemical, pharmaceutical, water treatment, and food processing. In these industries, with the continuous optimization of production processes and the gradual improvement of product quality requirements, more stringent requirements are being placed on the accuracy, stability, and response speed of metering pump flow regulation.

[0003] Patent publication number CN103362769B discloses a metering pump with an integral eccentric wheel stroke adjustment mechanism. By controlling the lifting and lowering of the hollow shaft, the eccentricity of the eccentric wheel can be adjusted, thereby changing the stroke of the metering pump and realizing stepless adjustment of the metering pump. On this basis, the lifting and lowering of the hollow shaft can be controlled by the adjusting rod to achieve precise control of the metering pump flow.

[0004] There are various methods for controlling the raising and lowering of the adjusting rod, including lead screws, linear motors, or cylinders. Analysis of these methods reveals the following drawbacks in existing technologies: lead screws or motors have slow response speeds, while cylinders have low adjustment precision; during power outages, if the control solenoid valves or other electrical components of the cylinder lose power and cannot maintain their original state, the cylinder may also lose control of the adjusting rod, failing to maintain the set position and potentially causing a series of safety issues; during water and power outages, a return spring is required to reset the adjusting rod to the zero-stroke position of the metering pump. Existing return springs are repeatedly compressed during the up-and-down movement of the adjusting rod, affecting their lifespan. Utility Model Content

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this utility model provides a pneumatic adjustment structure specifically for metering pumps, which has the advantages of fast response speed, high adjustment accuracy, automatic reset in the event of power failure, and long service life. It solves the problems of difficulty in balancing response speed and adjustment accuracy, lack of power failure safety protection mechanism, and short life of reset spring.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, this utility model provides the following technical solution:

[0009] A pneumatic adjustment structure for a metering pump includes a cylinder, a piston inside the cylinder, one end of a push rod fixedly connected to the piston, a reset rod slidably connected inside the other end of the push rod, an adjustment rod fixedly connected to the reset rod, and a positioning calibration device provided on the reset rod.

[0010] The push rod has a negative pressure chamber inside the cavity for sliding connection of the reset rod. A negative pressure is formed in the negative pressure chamber by an air pump to provide an inward suction force for the reset rod. A return spring is provided on the negative pressure chamber to provide an outward sliding force for the reset rod. An electromagnet is also provided on the push rod at the position of the negative pressure chamber. The end of the reset rod near the electromagnet is made of magnetic material.

[0011] Under the combined attraction of the negative pressure chamber and the electromagnet, the reset rod is tightly attracted to the push rod during normal operation. When the power is off, the negative pressure chamber is connected to the outside air pressure, and the electromagnet loses its electromagnetic attraction force. Under the action of the return spring, the reset rod descends rapidly, causing the metering pump flow to return to zero.

[0012] Preferably, a No. 1 air port is provided below the cylinder, and the No. 1 air port is connected to an air pump through a No. 1 air supply pipe; a No. 2 air port is provided above the cylinder, and the No. 2 air port is connected to an air pump through a No. 2 air passage pipe.

[0013] The push rod is provided with a No. 3 air port inside the cylinder, which is connected to the negative pressure chamber. A No. 4 air port is provided above the cylinder. The No. 3 air port is connected to the No. 4 air port through a No. 3 air pipe. The No. 4 air port is connected to a No. 4 air supply pipe.

[0014] An electromagnetic valve is installed on the fourth air supply pipe. The fourth air supply pipe is connected to the middle section of the first air supply pipe. When the power is off, the air valve inside the electromagnetic valve opens, and the negative pressure chamber is connected to the lower space inside the cylinder through the first and fourth air supply pipes. Under the negative pressure of the negative pressure chamber, the air pressure below the cylinder is reduced, making the piston descend more rapidly.

[0015] Preferably, the positioning calibration device includes a spur gear mounting base fixedly connected to the reset rod, on which spur gears are fixed. The positioning calibration device also includes a positioner, which is fixedly mounted on a housing that is fixedly connected to the cylinder housing. A gear is fixed on the positioner shaft of the positioner, and the gear meshes with the spur gears. During the lifting and lowering of the reset rod, the spur gears and the gears drive the positioner shaft to rotate, thereby obtaining the precise position of the reset rod.

[0016] Preferably, the positioner has a control panel located outside the housing.

[0017] Preferably, the push rod has two sealing rings on the contact surface through the cylinder housing.

[0018] Preferably, the solenoid valve includes a plug and an electromagnetic generator. The plug is made of a magnetic adsorption material. When energized, the plug provides an adsorption force to the electromagnetic generator, causing the electromagnetic generator to block the No. 4 gas supply pipe. A spring is provided between the plug and the electromagnetic generator. When the power is off, the spring pushes the electromagnetic generator to move, keeping the No. 4 gas supply pipe unobstructed.

[0019] Preferably, the cavity inside the push rod for sliding the reset rod is a sliding cavity, the negative pressure cavity is located at one end of the sliding cavity near the inside of the push rod, the diameter of the negative pressure cavity is smaller than the diameter of the sliding cavity, and the electromagnet is located at the stepped opening of the sliding cavity and the negative pressure cavity;

[0020] An electromagnetic coil is installed inside the electromagnet, and a magnetic adsorption material is provided at the end of the reset rod.

[0021] Preferably, a gas filter is provided at the connection between the No. 1 gas supply pipe and the No. 4 gas supply pipe. The gas filter is used to filter impurities and moisture in the gas to prevent impurities from entering the negative pressure chamber and cylinder and affecting the normal operation of the equipment.

[0022] Preferably, the No. 3 vent pipe is a pipe with bending and expansion function, which can adapt to the use requirements of high pressure and low pressure environments.

[0023] The wall of the No. 3 vent pipe adopts a multi-layer composite structure, with the inner layer being a polytetrafluoroethylene (PTFE) material layer. This PTFE material layer has good chemical stability and a low coefficient of friction, which can prevent corrosion caused by gas flowing in the pipe and reduce gas flow resistance.

[0024] The middle layer is a high-strength steel wire braided layer, which is woven from multiple steel wires. It can effectively enhance the pressure resistance of the No. 3 vent pipe and prevent it from breaking under high pressure.

[0025] The outer layer is a chloroprene rubber material layer, which has good flexibility and weather resistance, and can protect the internal structure from the influence of external environmental factors.

[0026] (III) Beneficial Effects

[0027] Compared with the prior art, this utility model provides a pneumatic regulating structure for metering pumps, which has the following advantages:

[0028] 1. This metering pump features a dedicated pneumatic regulating structure. It incorporates two sliding push rods and a reset rod. A return spring, necessary during power outages, is installed within the sliding cavity of the push rod and reset rod. The portion of the sliding cavity containing the return spring, i.e., the negative pressure cavity, is kept under negative pressure. During normal operation, this negative pressure attracts the reset rod, causing it to retract within the push rod. Simultaneously, an electromagnet enhances the stability of the reset rod's attraction. During power outages, the solenoid valve opens, eliminating the negative pressure in the negative pressure cavity. Simultaneously, the electromagnet loses its magnetic force, and under the action of the return spring, the reset rod slides downwards, returning the metering pump's stroke to zero. This structure, with the return spring located within the sliding cavity, prevents reciprocating compression of the spring during normal operation, reducing energy loss and extending the spring's lifespan.

[0029] 2. This metering pump features a dedicated pneumatic regulating structure. It connects the negative pressure chamber to the first air supply pipe via air inlet No. 3, air pipe No. 3, air inlet No. 4, and air supply pipe No. 4. During normal operation, the fourth air supply pipe is disconnected from the first air supply pipe under the action of the solenoid valve. During a power outage, the fourth air supply pipe connects to the space below the cylinder via the first air supply pipe. The negative pressure within the negative pressure chamber reduces the air pressure in the space below the cylinder, causing the piston to slide downwards along the push rod. Simultaneously, the reset rod slides downwards relative to the push rod, and the electromagnet releases its attraction to the reset rod. Under this triple action, the regulating rod descends faster during a power outage. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the pneumatic metering adjustment structure for metering pumps of this utility model.

[0031] Figure 2 This is a cross-sectional view of the pneumatic regulating structure for metering pumps according to this utility model.

[0032] Figure 3 This is a partially enlarged cross-sectional view of the piston, push rod, and reset rod of the pneumatic metering adjustment structure for the metering pump of this utility model.

[0033] Figure 4 This is a schematic diagram of the positioning and calibration device for the pneumatic metering adjustment structure of the metering pump of this utility model.

[0034] Figure 5 This is a schematic diagram of the air delivery pipe for the pneumatic metering pump of this utility model.

[0035] Figure 6 This is a cross-sectional view of the air delivery pipe of the pneumatic metering adjustment structure for the metering pump of this utility model.

[0036] In the diagram: 1. Cylinder; 2. Positioning and calibration device; 3. Piston; 4. Push rod; 5. Reset rod; 6. Adjusting rod; 9. Solenoid valve;

[0037] 21. Spur gear mounting base; 22. Spur gear; 23. Gear; 24. Positioner; 25. Control panel;

[0038] 41. Negative pressure chamber; 42. Electromagnet;

[0039] 71. Air inlet No. 1; 72. Air inlet No. 2; 73. Air inlet No. 3; 74. Air inlet No. 4;

[0040] 81. Gas Pipeline No. 1; 82. Gas Pipeline No. 4;

[0041] 91. Plug; 92. Electromagnetic generator. Detailed Implementation

[0042] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0043] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0044] In addition, a fixed connection refers to a connection in which parts or components are fixed and there is no relative movement; a transmission connection refers to a connection in which mechanical motion or torque is transmitted to other working parts through a transmission component; a sliding connection refers to a connection in which two objects are in contact but not fixed and can slide relative to each other; and a rotational connection refers to a connection in which two objects are in contact but not fixed and can rotate relative to each other.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] Example 1:

[0047] This embodiment provides a dedicated pneumatic regulating structure for metering pumps, which has the following technical features.

[0048] Please see Figure 1-6 A pneumatic adjustment structure for metering pumps includes a cylinder 1, a piston 3 inside the cylinder 1, one end of a push rod 4 fixedly connected to the piston 3, a reset rod 5 slidably connected inside the other end of the push rod 4, an adjustment rod 6 fixedly connected to the reset rod 5, and a positioning calibration device 2 on the reset rod 5.

[0049] The push rod 4 has a negative pressure chamber 41 in the cavity for sliding connection of the reset rod 5. The negative pressure chamber 41 is formed by an air pump to provide an inward suction force for the reset rod 5. A return spring is provided on the negative pressure chamber 41 to provide an outward sliding force for the reset rod 5. An electromagnet 42 is also provided on the push rod 4 at the position of the negative pressure chamber 41. The end of the reset rod 5 near the electromagnet 42 is made of magnetic material.

[0050] Under the dual attraction of the negative pressure chamber 41 and the electromagnet 42, the reset rod 5 is tightly attracted to the push rod 4 during normal operation. When the power is off, the negative pressure chamber 41 is connected to the outside air pressure and the electromagnet 42 loses its electromagnetic attraction force. Under the action of the return spring, the reset rod 5 descends rapidly, so that the flow of the metering pump returns to zero.

[0051] Further, a No. 1 air port 71 is provided below the cylinder 1, and the No. 1 air port 71 is connected to the air pump through the No. 1 air supply pipe 81. A No. 2 air port 72 is provided above the cylinder 1, and the No. 2 air port 72 is connected to the air pump through the No. 2 air passage pipe.

[0052] The push rod 4 is provided with a No. 3 air port 73 inside the cylinder 1. The No. 3 air port 73 is connected to the negative pressure chamber 41. The No. 4 air port 74 is provided above the cylinder 1. The No. 3 air port 73 is connected to the No. 4 air port 74 through the No. 3 air pipe. The No. 4 air port 74 is connected to the No. 4 air supply pipe 82.

[0053] A solenoid valve 9 is installed on the fourth air supply pipe 82. The fourth air supply pipe 82 is connected to the middle section of the first air supply pipe 81. When the power is off, the air valve inside the solenoid valve 9 opens, and the negative pressure chamber 41 is connected to the lower space inside the cylinder 1 through the first air supply pipe 81 and the fourth air supply pipe 82. Under the negative pressure of the negative pressure chamber 41, the air pressure below the cylinder 1 is reduced, so that the piston 3 descends more rapidly.

[0054] Furthermore, the positioning calibration device 2 includes a spur gear mounting base 21 fixedly connected to the reset rod 5, on which a spur gear 22 is fixed. The positioning calibration device 2 also includes a positioner 24, which is fixedly mounted on a housing that is fixedly connected to the outer shell of the cylinder 1. A gear 23 is fixed on the positioner shaft of the positioner 24, and the gear 23 meshes with the spur gear 22. During the lifting and lowering of the reset rod 5, the spur gear 22 and the gear 23 drive the shaft of the positioner 24 to rotate, thereby obtaining the precise position of the reset rod 5.

[0055] It should be noted that the positioner 24 is a rotary encoder. An encoder is a rotary sensor that converts rotary displacement into a series of digital pulse signals. Inside the rotary encoder is a photoelectric code disk with a central shaft. The code disk is engraved with ring-shaped light and dark lines. Through photoelectric transmitting and receiving devices, four sets of sine wave signals can be obtained, which are combined into A, B, C, and D. Each sine wave is 90 degrees out of phase. By inverting the C and D signals and superimposing them on the A and B phases, the signal stability can be enhanced. In addition, a Z-phase pulse is output for each revolution to represent the zero position reference position. The forward and reverse rotation of the encoder can be determined by the phase difference between the A and B phases. Combined with the Z-phase pulse, the zero position reference can be determined, thereby monitoring the number of revolutions and angle of the gear rotation in real time.

[0056] Furthermore, the locator 24 has a control panel 25 located outside the housing.

[0057] Furthermore, the push rod 4 has two layers of sealing rings on the contact surface that passes through the housing of cylinder 1.

[0058] Furthermore, the solenoid valve 9 includes a plug 91 and an electromagnetic generator 92. The plug 91 is made of magnetic adsorption material. When energized, the plug 91 provides an adsorption force to the electromagnetic generator 92, causing the electromagnetic generator 92 to block the No. 4 gas supply pipe 82. A spring is installed between the plug 91 and the electromagnetic generator 92. When de-energized, the spring pushes the electromagnetic generator 92 to move, keeping the No. 4 gas supply pipe 82 unobstructed.

[0059] It should be noted that magnetic adsorption materials include iron, cobalt, nickel, and other magnetic alloys, such as silicon steel sheets, which are silicon-iron alloys with a silicon content of 0.5%-4.5%.

[0060] Furthermore, the cavity inside the push rod 4 for sliding the reset rod 5 is a sliding cavity, and the negative pressure cavity 41 is located at one end of the sliding cavity near the inside of the push rod 4. The diameter of the negative pressure cavity 41 is smaller than the diameter of the sliding cavity, and the electromagnet 42 is located at the stepped opening of the sliding cavity and the negative pressure cavity 41.

[0061] An electromagnetic coil is installed inside the electromagnet 42, and a magnetic adsorption material is installed at the end of the reset rod 5.

[0062] It should be noted that magnetic adsorption materials include iron, cobalt, nickel, and other magnetic alloys, such as silicon steel sheets, which are silicon-iron alloys with a silicon content of 0.5%-4.5%.

[0063] It should be noted that the electromagnetic coil is connected to the power supply, and the No. 1 air supply pipe 81 and the No. 2 air supply pipe are connected to different air pumps. The two air pumps are connected to the same power supply as the electromagnet 42 and the plug 91.

[0064] Furthermore, a gas filter is installed at the connection between the No. 1 gas supply pipe 81 and the No. 4 gas supply pipe 82. The gas filter is used to filter impurities and moisture in the gas to prevent impurities from entering the negative pressure chamber 41 and the cylinder 1, which would affect the normal operation of the equipment.

[0065] Furthermore, the No. 3 vent pipe is designed to be flexible and expandable, enabling it to adapt to both high-pressure and low-pressure environments.

[0066] The wall of the No. 3 vent pipe adopts a multi-layer composite structure. The inner layer is a polytetrafluoroethylene (PTFE) material layer. This PTFE material layer has good chemical stability and low friction coefficient, which can prevent corrosion caused by gas flowing in the pipe and reduce gas flow resistance.

[0067] The middle layer is a high-strength steel wire braided layer, which is woven from multiple steel wires. It can effectively enhance the pressure resistance of the No. 3 vent pipe and prevent it from breaking under high pressure.

[0068] The outer layer is made of neoprene rubber, which has good flexibility and weather resistance, and can protect the internal structure from the influence of external environmental factors.

[0069] The lifting principle of piston 3 in cylinder 1: The air pump introduces high-pressure gas into the space above cylinder 1 (the space above piston 3 in cylinder 1) through the second air pipe. The air pump also extracts gas from the space below cylinder 1 (the space below piston 3 in cylinder 1) through the first air pipe 81, creating a negative pressure that causes piston 3 to slide downwards. Piston 3 then drives the reset rod 5 and adjusting rod 6 to slide downwards. The air pump also extracts gas from the space above cylinder 1 through the second air pipe, creating a negative pressure that causes piston 3 to slide downwards. The air pump then introduces high-pressure gas from the space below cylinder 1 through the first air pipe 81, causing piston 3 to slide upwards. Piston 3 then drives the reset rod 5 and adjusting rod 6 to slide upwards.

[0070] The principle of return to position during power failure: When power fails, regardless of the position of piston 3, the negative pressure chamber 41 is connected to the fourth air supply pipe 82 through the third air supply pipe. After the power failure, the plug 91 in the fourth air supply pipe 82 loses its magnetic force, causing the electromagnetic generator 92 to slide under the action of the spring, opening the passage of the fourth air supply pipe 82, thus connecting the negative pressure chamber 41 to the space below cylinder 1. The air pressure in the negative pressure chamber 41 rises rapidly, causing the reset rod 5 to slide downward relative to the push rod 4 under the action of the return spring. The air pressure in the space below cylinder 1 drops, causing the push rod 4 to slide downward. After the power failure, the electromagnet 42 loses its magnetic force, reducing the upward attraction force on the reset rod 5. Under the action of these three factors, the reset rod 5 descends rapidly, thereby bringing the stroke of the metering pump to zero through the adjusting rod 6.

[0071] In summary, this dedicated pneumatic regulating structure for metering pumps, by setting two mutually sliding push rods 4 and reset rods 5, incorporates a return spring, which is required during power outages, within the sliding cavity of the push rods 4 and reset rods 5. The portion of the sliding cavity containing the return spring, i.e., the negative pressure cavity 41, is set with negative pressure. During normal operation, this negative pressure attracts the reset rod 5, causing it to retract within the push rod 4. Simultaneously, an electromagnet 42 enhances the stability of the attraction to the reset rod 5. During power outages, the solenoid valve opens, eliminating the negative pressure in the negative pressure cavity 41. Simultaneously, the electromagnet 42 loses its magnetic force, and under the action of the return spring, the reset rod 5 slides downwards, returning the metering pump stroke to zero. This structure, with the return spring located within the sliding cavity, prevents reciprocating compression of the spring during normal operation, reducing energy loss and extending the spring's lifespan.

[0072] This metering pump features a dedicated pneumatic regulating structure. By using air inlet 73, air pipe 3, air inlet 74, and air supply pipe 82, the negative pressure chamber 41 is connected to the air supply pipe 81. During normal operation, the air supply pipe 82 is disconnected from the air supply pipe 81 under the action of the solenoid valve 9. When power is off, the air supply pipe 82 connects to the space below the cylinder 1 through the air supply pipe 81. The negative pressure in the negative pressure chamber 41 reduces the air pressure in the space below the cylinder 1, causing the piston 3 to drive the push rod 4 to slide downward. At the same time, the reset rod 5 slides downward relative to the push rod 4, and the electromagnet 42 releases its attraction to the reset rod 5. Under the triple action, the speed at which the regulating rod 6 descends during power failure is accelerated.

[0073] 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 said element.

[0074] Although embodiments of the present 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 present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pneumatic regulating structure for metering pumps, characterized in that, Includes a cylinder (1), a piston (3) is provided inside the cylinder (1), the piston (3) is fixedly connected to one end of a push rod (4), a reset rod (5) is slidably connected inside the other end of the push rod (4), the reset rod (5) is fixedly connected to an adjusting rod (6), and a positioning calibration device (2) is provided on the reset rod (5); The push rod (4) has a negative pressure chamber (41) in the cavity for sliding connection of the reset rod (5). The negative pressure chamber (41) is formed by an air pump to provide an inward suction force to the reset rod (5). A return spring is provided on the negative pressure chamber (41) to provide an outward sliding force to the reset rod (5). An electromagnet (42) is also provided on the push rod (4) at the position of the negative pressure chamber (41). The end of the reset rod (5) near the electromagnet (42) is made of magnetic material.

2. The pneumatic regulating structure for a metering pump according to claim 1, characterized in that, A first air port (71) is provided below the cylinder (1), and the first air port (71) is connected to the air pump through a first air supply pipe (81). A second air port (72) is provided above the cylinder (1), and the second air port (72) is connected to the air pump through a second air supply pipe. The push rod (4) is provided with a No. 3 air port (73) inside the cylinder (1), the No. 3 air port (73) is connected to the negative pressure chamber (41), the No. 4 air port (74) is provided above the cylinder (1), the No. 3 air port (73) is connected to the No. 4 air port (74) through the No. 3 air pipe, and the No. 4 air port (74) is connected to the No. 4 air supply pipe (82); A solenoid valve (9) is installed on the fourth gas pipe (82), and the fourth gas pipe (82) is connected to the middle section of the first gas pipe (81).

3. The pneumatic regulating structure for a metering pump according to claim 2, characterized in that, The positioning calibration device (2) includes a straight tooth mounting base (21) fixedly connected to the reset rod (5), and a straight tooth (22) fixed on the straight tooth mounting base (21). The positioning calibration device (2) also includes a locator (24), which is fixedly mounted on a housing that is fixedly connected to the housing of the cylinder (1). A gear (23) is fixed on the locator shaft of the locator (24), and the gear (23) meshes with the straight tooth (22). During the lifting and lowering process of the reset rod (5), the spur tooth (22) and the gear (23) drive the shaft of the locator (24) to rotate, thereby obtaining the precise position of the reset rod (5).

4. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, The locator (24) has a control panel (25) on its exterior.

5. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, The push rod (4) has two sealing rings on the contact surface that passes through the housing of the cylinder (1).

6. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, The solenoid valve (9) includes a plug (91) and an electromagnetic generator (92). The plug (91) is made of magnetic adsorption material. When the power is on, the plug (91) provides an adsorption force to the electromagnetic generator (92) so that the electromagnetic generator (92) blocks the No. 4 gas pipe (82). A spring is provided between the plug (91) and the electromagnetic generator (92). When the power is off, the spring pushes the electromagnetic generator (92) to move so that the No. 4 gas pipe (82) remains unobstructed.

7. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, The cavity inside the push rod (4) for sliding the reset rod (5) is a sliding cavity. The negative pressure cavity (41) is located at one end of the sliding cavity near the inside of the push rod (4). The diameter of the negative pressure cavity (41) is smaller than the diameter of the sliding cavity. The electromagnet (42) is located at the stepped opening of the sliding cavity and the negative pressure cavity (41). An electromagnetic coil is provided inside the electromagnet (42), and a magnetic adsorption material is provided at the end of the reset rod (5).

8. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, A gas filter is provided at the connection between the No. 1 gas pipe (81) and the No. 4 gas pipe (82). The gas filter is used to filter impurities and moisture in the gas to prevent impurities from entering the negative pressure chamber (41) and the cylinder (1) and affecting the normal operation of the equipment.

9. The pneumatic regulating structure for a metering pump according to claim 3, characterized in that, The No. 3 vent pipe is a pipe with bending and expansion functions, which can adapt to the use requirements of high pressure and low pressure environments. The pipe wall of the No. 3 vent pipe adopts a multi-layer composite structure, with an inner layer of polytetrafluoroethylene material, a middle layer of high-strength steel wire braided layer, which is woven from multiple steel wires, and an outer layer of neoprene rubber material.

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