Large precision syringe pump

Abstract

The utility model discloses a large -scale precision injection pump, including motor, screw rod, connecting nut, cylinder and pump piston, connecting nut is connected with screw rod, connecting nut moves along screw rod axial direction through guide mechanism, pump piston is connected with connecting nut and extends into cylinder, be equipped with inlet and outlet liquid hole on the cylinder still, including shaft coupling, support bearing and screw rod bearing seat, motor drives screw rod rotation through shaft coupling, screw rod is connected with screw rod bearing seat through support bearing, the utility model has simple structure, can realize continuous stable liquid outlet, and high measurement precision, work reliability higher advantage.

Description

Technical Field

[0001] This utility model relates to the field of fluid transport technology, specifically a large precision injection pump. Background Technology

[0002] Existing precision-metering syringe pumps use a motor to drive a lead screw, which in turn drives a nut that is threaded to it to move up and down. The nut in turn drives a piston that extends into the cylinder to move up and down, thus achieving the intake and exhaust of fluid. They are generally used in laboratory settings such as medical and biological experiments. However, they have low pressure resistance, small capacity, and short lifespan, and cannot be used in large-capacity, high-pressure industrial applications.

[0003] In existing industrial applications, peristaltic pumps and diaphragm pumps are generally used for fluid transport. A peristaltic pump consists of a driver, a pump head, and a hose. The driver provides power, the pump head enables fluid transport, and the hose is the channel for transporting fluid. The driver drives the impeller inside the pump head to rotate, and the pressure blocks on the impeller squeeze the hose in sequence, causing the hose to deform at the contact point, thereby pushing the fluid forward. As the impeller continues to rotate, the pressure blocks leave the squeezed part of the hose, the hose returns to its original shape, creating a vacuum, and the fluid is drawn into the hose. This cycle repeats to achieve fluid transport.

[0004] A diaphragm pump consists of a drive mechanism and a diaphragm. The drive mechanism drives the diaphragm to move back and forth, changing the volume of the cylinder to draw in and discharge liquid. When the diaphragm pump moves to one side of the drive mechanism, the working chamber in the cylinder will draw in liquid under negative pressure. When the diaphragm moves to the other side, it will discharge the liquid.

[0005] Peristaltic pumps and diaphragm pumps, due to their structural design, allow fluid to flow in a pulsed manner, making it impossible to achieve continuous liquid delivery, and they also have low metering accuracy. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a large precision injection pump that has a simple structure, can achieve continuous and stable liquid output, has high metering accuracy, high operational reliability, and is suitable for large-capacity and high-flow-rate applications.

[0007] The technical solution adopted by this utility model to solve its technical problem is:

[0008] A large precision injection pump includes a motor, a lead screw, a connecting nut, a cylinder, and a pump piston. The connecting nut is connected to the lead screw and moves axially along the lead screw via a guide mechanism. The pump piston is connected to the connecting nut and extends into the cylinder. The cylinder has inlet and outlet holes. The pump is characterized by further including a coupling, a support bearing, and a lead screw bearing seat. The motor drives the lead screw to rotate via the coupling, and the lead screw is connected to the lead screw bearing seat via the support bearing.

[0009] In high-capacity, high-flow-rate applications, the rotation of the lead screw drives the connecting nut and pump piston to move, resulting in significant thrust and pull. The coupling effectively isolates the axial force from being directly transmitted to the motor, preventing motor damage and increasing its lifespan. It also absorbs vibrations and shocks generated during motor start-up and shutdown, protecting both the motor and the lead screw. The support bearing ensures the stability of the lead screw's rotation while reducing axial force transmission, further extending the motor's lifespan. The combination of the coupling and support bearing is suitable for the continuous and stable infusion requirements of high-capacity, high-flow-rate applications, ensuring high-precision flow control.

[0010] The motor described in this invention is a stepper motor, and the lead screw is a ball screw; it is suitable for applications requiring high precision and high performance.

[0011] The support bearing described in this utility model is a thrust bearing, an angular contact bearing, or a tapered roller bearing; it is suitable for heavy-duty and high-precision applications.

[0012] The motor described in this utility model is connected to the coupling via a reducer; the reducer can reduce the speed and increase the torque to meet the requirements of low-speed operation, and improve the load capacity and control accuracy.

[0013] The cylinder body of this utility model is covered by a pump housing, and the cylinder body, the lead screw bearing seat and the pump housing are fixedly connected.

[0014] This invention also includes a limit detection mechanism, comprising an upper limit detection sensor, a lower limit detection sensor, and a detection strip. The upper and lower limit detection sensors are mounted on the pump housing, and the detection strip moves up and down synchronously with the pump piston. The detection strip cooperates with the upper and lower limit detection sensors. During the up-and-down movement of the pump piston, the detection strip moves up and down, and by cooperating with the upper and lower limit detection sensors, it monitors whether the pump piston has moved to the limit position. This effectively prevents the impact of drive mechanism failure on the liquid extraction or injection volume, ensuring accurate control of the liquid flow rate.

[0015] The pump housing of this utility model is provided with a guide groove arranged along the moving direction of the pump piston, and the guide mechanism is slidably engaged with the guide groove.

[0016] The guiding mechanism includes a guide bracket and a guide bearing. The guide bracket moves axially with the connecting nut and the pump piston. The guide bearing is installed at one end of the guide bracket and rolls with the guide groove. The guide bearing ensures that the connecting nut can move axially along the lead screw while reducing friction.

[0017] The connecting nut outer fixing sleeve of this utility model has a limiting sleeve. The upper end of the connecting nut extends radially outward to form a connecting boss. The upper end face of the limiting sleeve abuts against the lower end face of the connecting boss.

[0018] The limiting sleeve has an upper limiting sleeve section and a lower limiting sleeve section. The outer diameter of the upper limiting sleeve section is smaller than the outer diameter of the lower limiting sleeve section. A guide bracket limiting surface is formed between the upper limiting sleeve section and the lower limiting sleeve section.

[0019] The guide bracket has a bracket through hole, and the guide bracket is fitted onto the upper section of the limiting sleeve through the bracket through hole. The upper end face of the guide bracket abuts against the lower end face of the connecting boss, and the lower end face of the guide bracket abuts against the limiting surface of the guide bracket.

[0020] The upper section of the limiting sleeve has a front outer limiting plane on the front side and a rear outer limiting plane on the rear side, and the front outer limiting plane and the rear outer limiting plane are symmetrically arranged.

[0021] The bracket has a front inner limiting plane on the front side of the perforated inner wall and a rear inner limiting plane on the rear side of the inner wall. The front inner limiting plane and the rear inner limiting plane are symmetrically arranged.

[0022] The front inner limiting plane cooperates with the front outer limiting plane, and the rear inner limiting plane cooperates with the rear outer limiting plane; to achieve the limiting of the guide bracket, the structure is simple and easy to install, so that the guide bracket can move up and down synchronously with the pump piston, while ensuring that the guide bracket can only move axially and not rotate circumferentially, further ensuring the stability of the pump piston's axial movement.

[0023] The pump housing of this invention is integrally molded; it has high structural strength and is easy to assemble.

[0024] The cylinder body of this utility model is also provided with a cleaning hole; the cylinder body adopts a through-sleeve structure, the upper end of the cylinder body is fixed with an upper end cover by fasteners, and the lower end is fixed with a lower end cover by fasteners; the cleaning hole is provided to realize the cleaning of the cylinder body, and the upper end cover and the lower end cover are provided to facilitate the installation, disassembly and maintenance of the cylinder body.

[0025] The beneficial effects of this invention are as follows: In large-capacity, high-flow-rate applications, the rotation of the lead screw drives the connecting nut and pump piston to move, resulting in significant thrust and pull. The coupling effectively isolates the axial force from being directly transmitted to the motor, preventing motor damage and increasing its service life. It also absorbs vibrations and impacts generated during motor start-up and shutdown, protecting the motor and lead screw. The support bearing ensures the stability of the lead screw rotation, reduces the transmission of axial force, and extends the motor's service life. The coupling and support bearing are suitable for the continuous and stable infusion requirements of large-capacity, high-flow-rate applications, ensuring high-precision flow control. The reducer reduces speed and increases torque, meeting low-speed operation requirements and improving load capacity and control accuracy. During the pump piston's up-and-down movement, the detection strip moves up and down. The detection strip, in conjunction with the upper and lower limit sensors, monitors whether the pump piston has reached its limit position, effectively preventing drive mechanism malfunctions from affecting the liquid extraction or injection volume and ensuring accurate liquid flow control. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the syringe pump.

[0027] Figure 2 This is a front view of the overall structure of the syringe pump.

[0028] Figure 3 yes Figure 2 Sectional view of AA.

[0029] Figure 4 This is a schematic diagram of the hidden pump housing structure of an injection pump.

[0030] Figure 5 This is a front view of the hidden pump housing structure of the injection pump.

[0031] Figure 6 yes Figure 5 BB section view.

[0032] Figure 7 This is a schematic diagram of the pump casing structure.

[0033] Figure 8 This is a schematic diagram of the guide support structure.

[0034] Figure 9 This is the main view of the limiting sleeve structure.

[0035] Figure 10 This is a schematic diagram of the limiting sleeve structure.

[0036] Figure 11 This is a schematic diagram of the limiting sleeve structure from another angle.

[0037] Appendix label: Motor-1;

[0038] Reducer-2;

[0039] Coupling-3;

[0040] Pump housing-4, guide groove-401;

[0041] Lead screw bearing housing-501, support bearing-502;

[0042] Lead screw-6;

[0043] Connecting nut-7, connecting boss-701;

[0044] Pump piston-8, upper outer section of piston-801, middle outer section of piston-802, lower outer section of piston-803, upper slot-804, upper inner wall section-805, lower inner wall section-806, inner limiting surface-807;

[0045] Limiting sleeve-9, upper section of limiting sleeve-901, front outer limiting plane-9011, rear outer limiting plane-9012, lower section of limiting sleeve-902, guide bracket limiting surface-903, circumferential limiting plate-904;

[0046] Guide bracket-10, bracket perforation-1001, front inner limit plane-10011, rear inner limit plane-10012, detection strip-1002, guide shaft-1003, guide bearing-1004;

[0047] Cylinder body-11, inlet / outlet port-1101, cleaning port-1102;

[0048] Top cover -12;

[0049] Lower end cap -13;

[0050] Upper limit detection sensor-1401, lower limit detection sensor-1402;

[0051] Sensor mounting plate -15;

[0052] Housing base-16. Detailed Implementation

[0053] The present invention will now be described in conjunction with the accompanying drawings and embodiments.

[0054] As shown in the attached figure, a large precision injection pump includes a motor 1, a reducer 2, a coupling 3, a support bearing 502, a lead screw bearing seat 501, a lead screw 6, a connecting nut 7, a cylinder body 11, and a pump piston 8. The motor 1 is connected to the reducer 2. The output shaft of the reducer 2 drives the lead screw 6 to rotate via the coupling 3. The motor is connected to a controller. The lead screw 6 is connected to the lead screw bearing seat 501 via the support bearing 502. The connecting nut 7 is connected to the lead screw 6 and moves axially along the lead screw 6 via a guide mechanism. The pump piston 8 is connected to the connecting nut 7 and extends into the cylinder body 11. The cylinder body 11 has inlet and outlet ports 1101.

[0055] In high-capacity, high-flow-rate applications, the rotation of the lead screw 6 drives the connecting nut 7 and the pump piston 8 to move, resulting in significant thrust and pull. The coupling 3 effectively isolates the axial force from being directly transmitted to the motor 1, preventing damage to the motor 1 and increasing its service life. It also absorbs vibrations and impacts generated during motor start-up and shutdown, protecting both the motor 1 and the lead screw 6. The support bearing 502 ensures the stability of the lead screw 6's rotation while reducing the transmission of axial force, extending the motor's service life. The combination of coupling 3 and support bearing 502 is suitable for the continuous and stable infusion requirements of high-capacity, high-flow-rate applications, ensuring high-precision flow control. The reducer 2 reduces the rotational speed and increases the torque, meeting the needs of low-speed operation and improving load capacity and control accuracy.

[0056] The motor 1 is a stepper motor, and the lead screw 6 is a ball screw; it is suitable for applications requiring high precision and high performance.

[0057] The support bearing 502 is a thrust bearing, an angular contact bearing, or a tapered roller bearing; it is suitable for heavy-duty and high-precision applications.

[0058] In this embodiment, the support bearings 502 are arranged in pairs.

[0059] The cylinder body 11 is fitted with a pump housing 4, and the cylinder body 11, the lead screw bearing seat 501, and the pump housing 4 are fixedly connected.

[0060] In this embodiment, the top of the pump housing 4 is provided with a shaft through hole for the output shaft of the reducer 2 to pass through. The reducer 2 is fixed to the top of the pump housing 4, and the output shaft of the reducer 2 is inserted into the shaft through hole and connected to the coupling 3 in the pump housing 4.

[0061] This embodiment also includes a limit detection mechanism, which comprises an upper limit detection sensor 1401, a lower limit detection sensor 1402, and a detection strip 1002. The upper limit detection sensor 1401 and the lower limit detection sensor 1402 are mounted on the pump housing 4 and are connected to the controller. The detection strip 1002 moves up and down synchronously with the pump piston 8 and cooperates with the upper limit detection sensor 1401 and the lower limit detection sensor 1402. During the up and down movement of the pump piston 8, the detection strip 1002 moves up and down. By cooperating with the upper limit detection sensor 1401 and the lower limit detection sensor 1402, the detection strip 1002 monitors whether the pump piston 8 has moved to the limit position, which can effectively prevent the impact of drive mechanism failure on the liquid extraction or injection volume and ensure the accurate control of liquid flow rate.

[0062] In this embodiment, the front side of the pump housing is set as an open structure, and a sensor fixing plate is provided at the opening on the front side of the pump housing. The two ends of the sensor fixing plate are fixedly connected to the pump housing respectively. An upper limit detection sensor 1401 is installed at the upper end of the sensor fixing plate, and a lower limit detection sensor 1402 is installed at the lower end.

[0063] In this embodiment, the upper limit detection sensor 1401 and the lower limit detection sensor 1402 are photoelectric sensors, and the detection strip 1002 is in sensing cooperation with the upper limit detection sensor 1401 and the lower limit detection sensor 1402.

[0064] The pump housing 4 has a guide groove 401 provided on the inner wall along the moving direction of the pump piston 8, and the guide mechanism is slidably engaged with the guide groove 401.

[0065] The guiding mechanism includes a guide bracket 10 and a guide bearing 1004. The guide bracket 10 moves axially with the connecting nut 7 and the pump piston 8. One end of the guide bracket 10 is fixedly connected to a guide shaft 1003, and the guide bearing 1004 is sleeved on the guide shaft. The inner ring of the guide bearing 1004 is fixedly connected to the guide shaft 1003, and the outer ring of the guide bearing 1004 is in rolling contact with the guide groove 401. The guide bearing 1004 ensures that the connecting nut 7 can move axially along the lead screw 6 while reducing friction.

[0066] The connecting nut 7 is fitted with a limiting sleeve 9. The upper end of the connecting nut 7 extends radially outward to form a connecting boss 701. The upper end face of the limiting sleeve 9 abuts against the lower end face of the connecting boss 701.

[0067] The limiting sleeve 9 is provided with an upper limiting sleeve section 901, a lower limiting sleeve section 902 and a circumferential limiting plate 904. The outer diameter of the upper limiting sleeve section 901 is smaller than the outer diameter of the lower limiting sleeve section 902. A guide bracket limiting surface 903 is formed between the upper limiting sleeve section 901 and the lower limiting sleeve section 902. The outer periphery of the lower limiting sleeve section 902 extends downward along the axial direction to form the circumferential limiting plate 904.

[0068] The guide bracket 10 has a bracket through hole 1001. The guide bracket 10 is fitted onto the upper section 901 of the limiting sleeve through the bracket through hole 1001. The upper end face of the guide bracket 10 abuts against the lower end face of the connecting boss 701, and the lower end face of the guide bracket 10 abuts against the guide bracket limiting surface 903.

[0069] This design achieves the limiting of the guide bracket 10, has a simple structure, is easy to install, and enables the guide bracket 10 to move up and down synchronously with the pump piston 8.

[0070] The upper section 901 of the limiting sleeve has a front outer limiting plane 9011 on the front side and a rear outer limiting plane 9012 on the rear side. The front outer limiting plane 9011 and the rear outer limiting plane 9012 are symmetrically arranged.

[0071] The bracket through-hole 1001 has a front inner limiting plane 10011 on the front side of the inner wall and a rear inner limiting plane 10012 on the rear side of the inner wall. The front inner limiting plane 10011 and the rear inner limiting plane 10012 are symmetrically arranged.

[0072] The front inner limiting plane 10011 is in contact with the front outer limiting plane 9011, and the rear inner limiting plane 10012 is in contact with the rear outer limiting plane 9012; this ensures that the guide bracket 10 can only move axially and cannot rotate circumferentially, further ensuring the stability of the axial movement of the pump piston 8.

[0073] In this embodiment, the limiting sleeve 9 is detachably connected to the connecting boss 701 of the connecting nut 7 via fasteners.

[0074] The outer surface of the pump piston 8 is axially formed with an upper outer section 801, a middle outer section 802, and a lower outer section 803. The outer diameter of the upper outer section 801 is smaller than that of the middle outer section 802, and the outer diameter of the middle outer section 802 is smaller than that of the lower outer section 803. A horizontally set upper limit surface is formed between the upper outer section 801 and the middle outer section 802. The circumferential limit plate 904 of the limiting sleeve 9 is sleeved on the upper outer section 801. The lower end face of the circumferential limit plate 904 abuts against the upper limit surface. The upper end face of the upper outer section 801 is connected to the lower end face of the limiting sleeve 9. The outer diameter of the lower outer section 803 matches the inner diameter of the cylinder 11. A sealing ring is provided between the lower outer section 803 and the inner wall of the cylinder 11.

[0075] The pump piston 8 has an axially oriented upper slot 804, which is open at the top and sealed at the bottom. The lead screw 6 passes through the connecting nut 7 and is inserted into the upper slot 804 of the pump piston 8.

[0076] The inner wall of the upper slot 804 forms an upper inner wall section 805 and a lower inner wall section 806. The inner diameter of the upper inner wall section 805 is larger than the inner diameter of the lower inner wall section 806. An inner limiting surface 807 is formed between the upper inner wall section 805 and the lower inner wall section 806.

[0077] The lower end face of the connecting nut 7 abuts against the inner limiting surface 807, and the upper section 805 of the inner wall of the pump piston 8 is fixedly connected to the outer wall of the connecting nut.

[0078] The bottom of the pump piston 8 is sealed to ensure the suction and sealing of the injection pump, enabling the liquid to be drawn into the cylinder 11. The lower section of the inner wall of the slotted upper section 804 has a small inner diameter, which further ensures the stability and sealing of the pump piston 8 as it moves up and down in the cylinder 11.

[0079] In this embodiment, the detection strip 1002 is installed at one end of the guide bracket 10; the guide bracket 10 moves axially to drive the detection strip 1002 to move up and down with the pump piston 8.

[0080] The cylinder body 11 is also provided with a cleaning hole 1102; the cylinder body 11 adopts a through sleeve structure, the upper end of the cylinder body 11 is fixed with an upper end cover 12 by fasteners, and the lower end is fixed with a lower end cover 13 by fasteners; the cleaning hole 1102 is provided to realize the cleaning of the cylinder body 11, and the upper end cover 12 and the lower end cover 13 are provided to facilitate the installation, disassembly and maintenance of the cylinder body.

[0081] In this embodiment, the liquid inlet / outlet hole 1101 is opened on the lower end cover 13, and the cleaning hole 1102 is opened on the upper end cover 12. The cleaning hole 1102 includes a cleaning water inlet and a cleaning water outlet. The cleaning water inlet is connected to an inlet pipe, and the cleaning water outlet is connected to an outlet pipe. The cleaning liquid enters the cylinder 11 from the inlet pipe to clean the cylinder 11, and then flows out from the outlet pipe.

[0082] In this embodiment, the upper end cover 12 is detachably and fixedly connected to the pump housing 4 by fasteners, the lower end cover 13 is detachably and fixedly connected to the housing base 16 by fasteners, and the housing base 16 is detachably and fixedly connected to the lower end of the pump housing 4 by fasteners; the structure is simple and easy to assemble.

[0083] In this embodiment, bolts are used as fasteners, which are easy to install and disassemble.

[0084] The pump inlet and outlet ports 1101 of the cylinder body 11 are connected to an inlet pipe and an outlet pipe. An inlet control solenoid valve is installed at the inlet pipe and an outlet control solenoid valve is installed at the outlet pipe. The inlet control solenoid valve and the outlet control solenoid valve are respectively connected to the controller.

[0085] The pump housing 4 is integrally molded; it has high structural strength and is easy to assemble.

[0086] In this embodiment, the size of the cylinder can be changed according to the actual capacity requirements.

[0087] In this embodiment, the controller is either an MCU-based controller or a PLC controller.

[0088] The large precision injection pump in this embodiment is used in a hypochlorous acid disinfectant generating device. The hypochlorous acid disinfectant generating device prepares hypochlorous acid disinfectant by mixing water, stock solution and carbon dioxide. The large precision injection pump is used to provide a precise metering of stock solution to the hypochlorous acid disinfectant generating device. This large precision injection pump is not only suitable for hypochlorous acid disinfectant generating devices, but also applicable to other occasions with large capacity, large flow rate requirements and high liquid delivery accuracy requirements.

[0089] When using this utility model:

[0090] 1. The controller controls motor 1 to work. The motor shaft of motor 1 rotates forward, driving the lead screw 6 to rotate forward via reducer 2 and coupling 3 (at this time, the inlet control solenoid valve is open and the outlet control solenoid valve is closed). The forward rotation of lead screw 6 drives the connecting nut 7 to move upward in the pump housing 4, drawing liquid into the cylinder 11 along the inlet pipe and inlet / outlet hole 1101. The controller controls the motor shaft of motor 1 to rotate in reverse, driving the lead screw 6 to rotate in reverse via reducer 2 and coupling 3 (at this time, the inlet control solenoid valve is closed and the outlet control solenoid valve is open). The reverse rotation of lead screw 6 drives the connecting nut 7 to move downward in the cylinder 11, pushing liquid out from the inlet / outlet hole 1101 and outlet pipe. During this process, the detection strip 1002 moves up and down with the pump piston 8. When the detection... When the detection bar 1002 moves downward to the position of the lower limit detection sensor 1402, the lower limit detection sensor 1402 senses the detection bar 1002 and feeds a signal back to the controller. When the detection bar 1002 moves upward to the position of the upper limit detection sensor 1401, the upper limit detection sensor 1401 senses the detection bar 1002 and feeds a signal back to the controller. When the detection bar 1002 can reach the position of either the lower limit detection sensor 1402 or the upper limit detection sensor 1401, it indicates that there are problems such as motor stepping inaccuracy, encoder failure, or drive circuit issues. The controller will then stop the motor to prevent the liquid delivery volume from not meeting the requirements.

[0091] 2. During the operation of the injection pump, high-pressure cleaning fluid enters the cylinder from the inlet pipe to clean the cylinder, and the cleaning fluid is discharged from the outlet pipe after cleaning.

Claims

1. A large precision injection pump, comprising a motor, a lead screw, a connecting nut, a cylinder, and a pump piston, wherein the connecting nut is connected to the lead screw and moves axially along the lead screw via a guide mechanism; the pump piston is connected to the connecting nut and extends into the cylinder; the cylinder has inlet and outlet ports, characterized in that: It also includes a coupling, a support bearing, and a lead screw bearing housing. The motor drives the lead screw to rotate via the coupling, and the lead screw is connected to the lead screw bearing housing via the support bearing.

2. A large precision injection pump according to claim 1, characterized in that: The motor is a stepper motor, and the lead screw is a ball screw.

3. A large precision injection pump according to claim 1 or 2, characterized in that: The support bearing is a thrust bearing, an angular contact bearing, or a tapered roller bearing.

4. A large precision injection pump according to claim 1 or 2, characterized in that: The motor is connected to the coupling via a reducer.

5. A large precision injection pump according to claim 1 or 2, characterized in that: The cylinder body is fitted with a pump housing, and the cylinder body, the lead screw bearing seat, and the pump housing are fixedly connected.

6. A large precision injection pump according to claim 5, characterized in that: It also includes a limit detection mechanism, which comprises an upper limit detection sensor, a lower limit detection sensor, and a detection strip. The upper and lower limit detection sensors are mounted on the pump housing, and the detection strip moves up and down synchronously with the pump piston. The detection strip cooperates with the upper and lower limit detection sensors.

7. A large precision injection pump according to claim 5, characterized in that: The pump housing is provided with a guide groove arranged along the direction of pump piston movement, and the guide mechanism is slidably engaged with the guide groove. The guiding mechanism includes a guide bracket and a guide bearing. The guide bracket moves axially with the connecting nut and the pump piston. The guide bearing is installed at one end of the guide bracket and rolls with the guide groove.

8. A large precision injection pump according to claim 7, characterized in that: The outer fixing sleeve of the connecting nut has a limiting sleeve, and the upper end of the connecting nut extends radially outward to form a connecting boss. The upper end face of the limiting sleeve abuts against the lower end face of the connecting boss. The limiting sleeve has an upper limiting sleeve section and a lower limiting sleeve section. The outer diameter of the upper limiting sleeve section is smaller than the outer diameter of the lower limiting sleeve section. A guide bracket limiting surface is formed between the upper limiting sleeve section and the lower limiting sleeve section. The guide bracket has a bracket through hole, and the guide bracket is fitted onto the upper section of the limiting sleeve through the bracket through hole. The upper end face of the guide bracket abuts against the lower end face of the connecting boss, and the lower end face of the guide bracket abuts against the limiting surface of the guide bracket. The upper section of the limiting sleeve has a front outer limiting plane on the front side and a rear outer limiting plane on the rear side, and the front outer limiting plane and the rear outer limiting plane are symmetrically arranged. The bracket has a front inner limiting plane on the front side of the perforated inner wall and a rear inner limiting plane on the rear side of the inner wall. The front inner limiting plane and the rear inner limiting plane are symmetrically arranged. The front inner limiting plane cooperates with the front outer limiting plane, and the rear inner limiting plane cooperates with the rear outer limiting plane.

9. A large precision injection pump according to claim 5, characterized in that: The pump housing is integrally molded.

10. A large precision injection pump according to claim 1, 2, 6, 7, 8, or 9, characterized in that: The cylinder body is also provided with a cleaning hole; the cylinder body adopts a through-sleeve structure, and the upper end of the cylinder body is fixed with an upper end cover by fasteners, and the lower end is fixed with a lower end cover by fasteners.

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