High-precision plunger pump with back clearance eliminating function

Abstract

The invention discloses a high-precision plunger pump with a back clearance eliminating function. The high-precision plunger pump comprises a control assembly, a pump head assembly and a plunger assembly. The control assembly comprises a motor and a supporting frame arranged on the motor, and the motor is connected with a lead screw. The pump head assembly comprises a cavity and a spacer ring, and a movable groove allowing the plunger rod to move is formed in the cavity. The plunger assembly comprises a connecting base and a plunger rod, the plunger rod is connected to the end, close to the spacer ring, of the connecting base, a lead screw connecting part is arranged at the end, away from the spacer ring, of the connecting base, a gap groove is formed in the lead screw connecting part in the radial direction, an annular groove is formed in the lead screw connecting part in the circumferential direction in a concave mode, and a first O-shaped ring is arranged in the annular groove in a sleeved mode. A guide hole seat is arranged beside the connecting seat, a guide shaft is arranged on the guide hole seat in a penetrating mode, and the guide shaft can be fixed in the first receding groove through the cavity. Due to the arrangement of the first O-shaped ring and the gap groove, the lead screw connecting part can be tightly attached to the thread of the lead screw, the return stroke difference of the lead screw and nut pair can be greatly reduced, and meanwhile the first O-shaped ring plays a role in abrasion compensation.

Description

Technical Field

[0001] The invention relates to the field of plunger pump technology, in particular to a high-precision plunger pump with a backlash elimination function. Background Art

[0002] In traditional technology, when using a plunger pump, it usually moves a certain distance when switching between suction and discharge (that is, when the nut changes its direction of movement) to eliminate the influence of backlash (also known as return difference). This operation seems simple, but it will add a series of invalid actions to the working sequence of the equipment, affecting the efficiency of the equipment. In addition, pump movement means liquid movement. In order to deal with this part of the liquid discharged to eliminate the return difference, some valves or flow channels are usually set up separately to achieve it, or switching and discharge actions are added. This not only interrupts the continuity of the equipment movement, but also increases the complexity and cost of the system. If the return difference is not eliminated, the pipetting accuracy will be poor, and there is a problem that it is difficult to improve both accuracy and system efficiency at the same time.

[0003] In the prior art, an anti-backlash plunger pump is disclosed, in which a lower nut, a nut spring, and a slider constitute an anti-backlash screw nut pair, the nut spring is in a compressed state, the spring force causes the lower nut to be subjected to a downward force, and the threaded slider is subjected to an upward force, so that the screw thread and the lower nut threaded slider are always in a fit state, reducing the return difference caused by the reverse process of the screw. However, under this structure, the teeth of the lower nut will wear after being used for a certain period of time, and the wear will cause precision errors, thereby affecting the suction and discharge accuracy of the plunger pump. In addition, the pump head is directly fixed to the bracket by screws, and the alignment between the pump head and the bracket is relatively inconvenient.

[0004] Therefore, it is necessary to design a new technical solution to solve the above problems. Summary of the invention

[0005] In view of this, the present invention aims at the deficiencies in the prior art, and its main purpose is to provide a high-precision plunger pump with a backlash elimination function, wherein a clearance groove penetrating the screw rod connecting part is opened in the radial direction of the screw rod connecting part, an annular groove is concavely arranged in the circumferential direction of the screw rod connecting part, a first O-ring for pressing the screw rod connecting part against the screw rod is sleeved in the annular groove, and the arrangement of the first O-ring and the clearance groove enables the screw rod connecting part to press against the screw thread of the screw rod, in which case the return stroke difference of the screw rod nut pair can be greatly reduced, and at the same time, when the thread of the screw rod connecting part is worn, the clamping force of the first O-ring can also make the screw rod connecting part It fits closely to the screw thread of the lead screw, plays a role in wear compensation, has an ingenious structural design, and is provided with a guide shaft and a guide hole seat, which limits the shaking of the connecting seat when it moves up and down, and thus limits the shaking of the plunger rod, so that the plunger rod maintains a vertical posture when entering and exiting the cavity, reducing the error between the theoretical calculated pipetting volume and the actual pipetting volume, and improving the pipetting accuracy of the plunger pump; and, the cavity is fixed to the end of the support frame away from the motor by screws passing through the spacer ring, and the cavity can fix the guide shaft in the first avoidance groove, so that the guide shaft can provide positioning for the installation of the pump head assembly, which is convenient for the assembly of the pump head assembly and the fixing of the guide shaft.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A high-precision plunger pump with backlash elimination function, comprising a control component, a pump head component and a plunger component;

[0008] The control assembly includes a motor and a support frame arranged on the motor, the motor is connected to a screw rod, the support frame is provided with a through slot extending vertically, and the screw rod is located in the through slot;

[0009] The pump head assembly includes a cavity and a spacer ring, wherein a movable groove for the plunger rod to move is arranged in the cavity, the spacer ring covers the movable groove and the through groove and is provided with an escape hole for the plunger rod to pass through, and the cavity is fixed to the end of the support frame away from the motor by screws passing through the spacer ring;

[0010] The plunger assembly can be movably arranged in the through groove, and the plunger assembly includes a connecting seat and a plunger rod, the plunger rod is connected to one end of the connecting seat close to the spacer ring, and the end of the plunger rod away from the connecting seat extends into the movable groove, and the end of the connecting seat away from the spacer ring is provided with a screw connecting part, and the screw connecting part is connected to the screw, and a clearance groove penetrating the screw connecting part is radially opened on the screw connecting part, and an annular groove is circumferentially recessed on the screw connecting part, and a first O-ring for pressing the screw connecting part against the screw is sleeved in the annular groove, and a guide hole seat is provided on the side of the connecting seat, and a guide shaft is passed through the guide hole seat, and a first avoidance groove for the guide hole seat to movably avoid is provided on the side of the through groove, and the end of the guide shaft away from the motor passes through the spacer ring and abuts against the bottom of the cavity, and the cavity can fix the guide shaft in the first avoidance groove.

[0011] As a preferred solution, the control component also includes a photoelectric switch, a shielding piece cooperating with the photoelectric switch is arranged on the side of the connecting seat, a second avoidance groove for the shielding piece to move around is opened on the side of the through groove, and the photoelectric switch is arranged on the support seat and extends into the second avoidance groove.

[0012] As a preferred solution, a sealing assembly is provided between the outer periphery of the plunger rod and the movable groove, and a first groove is recessed upwardly from the bottom of the cavity. Correspondingly, a protrusion matching the first groove is convexly provided on the top of the spacer ring, and the protrusion abuts against the first groove and fixes the sealing assembly to the cavity.

[0013] As a preferred embodiment, a second groove is formed on the top of the support frame on the outer periphery of the through groove, and correspondingly, an annular protrusion matching the second groove is formed on the bottom of the spacer ring, the bottom of the annular protrusion abuts against the second groove, and a third groove is formed upwardly in the annular protrusion, and the end of the connecting seat close to the spacer ring can extend into the third groove.

[0014] As a preferred embodiment, the sealing assembly includes a second O-ring, a sealing ring, a first sealing gasket and a second sealing gasket arranged in sequence, the sealing ring has a through hole, an annular extension portion extends from the end of the sealing ring away from the spacer ring, the second O-ring is sleeved outside the annular extension portion, a fourth groove is recessed on the top of the annular convex portion, and the first sealing gasket and the second sealing gasket are located in the fourth groove.

[0015] As a preferred solution, the outer periphery of the spacer ring is aligned with the outer periphery of the cavity.

[0016] As a preferred solution, a fifth groove is recessed at one end of the connecting seat close to the spacer ring, the plunger rod is inserted into the fifth groove, an annular groove is provided on the outer periphery of the plunger rod, a glue injection hole connected to the annular groove is provided on the outer periphery of the connecting seat, and the plunger rod is fixed in the fifth groove by structural glue.

[0017] As a preferred solution, a sixth groove is recessed downwardly at the bottom of the first avoidance groove, the guide shaft is inserted into the sixth groove, and the cavity can fix the guide shaft in the sixth groove.

[0018] As a preferred solution, a threaded hole matching the screw rod is provided in the screw rod connecting portion, and a third avoidance groove is opened upward at the top of the threaded hole, and the third avoidance groove extends into the connecting seat.

[0019] As a preferred solution, two clearance grooves are arranged perpendicularly and intersectingly, and the clearance groove passes through the threaded hole. Two annular grooves are arranged along the axial spacing of the screw connecting part, and correspondingly, two first O-rings are provided.

[0020] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0021] The main point is that a clearance groove penetrating the screw rod connection part is opened in the radial direction of the screw rod connection part, an annular groove is concavely arranged in the circumferential direction of the screw rod connection part, and a first O-ring for pressing the screw rod connection part against the screw rod is sleeved in the annular groove. The arrangement of the first O-ring and the clearance groove enables the screw rod connection part to press against the screw thread of the screw rod. In this case, the return stroke difference of the screw rod nut pair can be greatly reduced. At the same time, when the teeth of the screw rod connection part are worn, the clamping force of the first O-ring can also make the screw rod connection part press against the screw thread of the screw rod, thereby playing a role in wear compensation. The structural design The design is ingenious, and a guide shaft and a guide hole seat are provided, which limit the shaking of the connecting seat when it moves up and down, and then limit the shaking of the plunger rod, so that the plunger rod maintains a vertical posture when entering and exiting the cavity, reducing the error between the theoretical calculated pipetting volume and the actual pipetting volume, and improving the pipetting accuracy of the plunger pump; and the cavity is fixed to the end of the support frame away from the motor by screws passing through the spacer ring. The cavity can fix the guide shaft in the first avoidance groove, so that the guide shaft can provide positioning for the installation of the pump head assembly, which is convenient for the assembly of the pump head assembly and the fixing of the guide shaft.

[0022] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional schematic diagram of a preferred embodiment of the present invention;

[0024] Figure 2 It is an exploded schematic diagram of a preferred embodiment of the present invention;

[0025] Figure 3 It is a cross-sectional schematic diagram of a preferred embodiment of the present invention;

[0026] Figure 4 is another cross-sectional schematic diagram of a preferred embodiment of the present invention;

[0027] Figure 5 It is a schematic exploded view of the plunger assembly of a preferred embodiment of the present invention.

[0028] Description of the accompanying drawings:

[0029] 10. Control components 11. Motor

[0030] 12. Support frame 121. Through slot

[0031] 122. First avoidance slot 123. Second avoidance slot

[0032] 124, second groove 125, sixth groove

[0033] 13. Screw rod 14. Photoelectric switch

[0034] 20. Pump head assembly 21. Cavity

[0035] 211, movable groove 212, first groove

[0036] 213, connecting hole 22, spacer ring

[0037] 221, avoidance hole 222, raised part

[0038] 223, annular protrusion 224, third groove

[0039] 225, fourth groove 30, plunger assembly

[0040] 31. Connecting seat 311. Screw connecting part

[0041] 312, clearance groove 313, annular groove

[0042] 314, guide hole seat 315, fifth groove

[0043] 316, glue injection hole 317, threaded hole

[0044] 318, third avoidance groove 32, plunger rod

[0045] 321, annular groove 33, first O-ring

[0046] 34. Guide shaft 35. Shielding sheet

[0047] 40. Sealing assembly 41. Second O-ring

[0048] 42. Sealing ring 421. Through hole

[0049] 422, annular extension portion 43, first sealing gasket

[0050] 44. Second sealing gasket. DETAILED DESCRIPTION

[0051] First of all, it should be noted that in the description of the present invention, the terms "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0052] Please refer to Figures 1 to 5 As shown, it shows the specific structure of a preferred embodiment of the present invention, including a control component 10, a pump head component 20 and a plunger component 30.

[0053] The control assembly 10 includes a motor 11 and a support frame 12 disposed on the motor 11, the motor 11 is connected to a screw rod 13, the support frame 12 is provided with a through slot 121 extending vertically therethrough, and the screw rod 13 is located in the through slot 121;

[0054] The pump head assembly 20 includes a cavity 21 and a spacer ring 22. The cavity 21 is provided with a movable groove 211 for the plunger rod 32 to move. The spacer ring 22 covers the movable groove 211 and the through groove 121 and is provided with an escape hole 221 for the plunger rod 32 to pass through. The cavity 21 is fixed to the end of the support frame 12 away from the motor 11 by screws passing through the spacer ring 22.

[0055] The plunger assembly 30 can be movably arranged in the through groove 121. The plunger assembly 30 includes a connecting seat 31 and a plunger rod 32. The plunger rod 32 is connected to the end of the connecting seat 31 close to the spacer ring 22. The end of the plunger rod 32 away from the connecting seat 31 extends into the movable groove 211. The end of the connecting seat 31 away from the spacer ring 22 is provided with a screw connecting part 311. The screw connecting part 311 is connected to the screw 13. The screw connecting part 311 is radially provided with a gap groove 312 that penetrates the screw connecting part 311. The screw connecting part A circular groove 313 is recessed circumferentially around 311, and a first O-ring 33 is sleeved in the circular groove 313 for pressing the screw connecting portion 311 against the screw 13. A guide hole seat 314 is arranged on the side of the connecting seat 31, and a guide shaft 34 is passed through the guide hole seat 314. A first avoidance groove 122 is provided on the side of the through groove 121 for the guide hole seat 314 to move around. The end of the guide shaft 34 away from the motor 11 passes through the spacer ring 22 and abuts against the bottom of the cavity 21. The cavity 21 can fix the guide shaft 34 in the first avoidance groove 122.

[0056] See also Figure 2 and Figure 3 As shown, the motor 11 is provided with a rotating shaft, the screw rod 13 is tightly sleeved outside the rotating shaft, the control component 10 also includes a photoelectric switch 14, a shielding piece 35 cooperating with the photoelectric switch 14 is provided on the side of the connecting seat 31, and a second avoidance groove 123 for the shielding piece 35 to move around is opened on the side of the through groove 121, and the photoelectric switch 14 is arranged on the support seat and extends into the second avoidance groove 123; in this embodiment, the motor 11 is a stepping motor.

[0057] See also Figure 2 and Figure 3 As shown, a sealing assembly 40 is arranged between the outer periphery of the plunger rod 32 and the movable groove 211, and a first groove 212 is concavely arranged upwardly at the bottom of the cavity 21, and correspondingly, a convex portion 222 matching the first groove 212 is convexly arranged at the top of the spacer ring 22, and the convex portion 222 abuts against the first groove 212 and fixes the sealing assembly 40 to the cavity 21;

[0058] Specifically, a second groove 124 is formed on the top of the support frame 12 at the outer periphery of the through groove 121, and correspondingly, an annular convex portion 223 matching the second groove 124 is formed on the bottom of the spacer ring 22, the bottom of the annular convex portion 223 abuts against the second groove 124, and a third groove 224 is formed upwardly in the annular convex portion 223, and the end of the connecting seat 31 close to the spacer ring 22 can extend into the third groove 224; the sealing assembly 40 includes a second O-ring 41, a sealing ring 42, a first sealing gasket 43 and a second sealing gasket 44 which are sequentially arranged, the sealing ring 42 has a through hole 421, an annular extension portion 422 is extended from the end of the sealing ring 421 away from the spacer ring 22, the second O-ring 41 is sleeved outside the annular extension portion 422, a fourth groove 225 is formed on the top of the annular convex portion 223, and the first sealing gasket 43 and the second sealing gasket 44 are located in the fourth groove 225;

[0059] In this embodiment, the outer circumference of the spacer ring 22 and the outer circumference of the cavity 21 are both circular, and the outer circumference of the spacer ring 22 is aligned with the outer circumference of the cavity 21. The cavity 21 is provided with one or two connecting holes 213 for the entry and exit of liquid.

[0060] See also Figure 4 and Figure 5As shown, a fifth groove 315 is recessed at one end of the connecting seat 31 close to the spacer ring 22, the plunger rod 32 is inserted into the fifth groove 315, an annular groove 321 is provided on the outer periphery of the plunger rod 32, a glue injection hole 316 communicating with the annular groove 321 is provided on the outer periphery of the connecting seat 31, the plunger rod 32 is fixed in the fifth groove 315 by structural glue, a sixth groove 125 is recessed downward at the bottom of the first avoidance groove 122, the guide shaft 34 is inserted into the sixth groove 125, and the cavity 21 can fix the guide shaft 34 in the sixth groove 125;

[0061] Specifically, a threaded hole 317 matching the threaded rod 13 is disposed in the threaded rod connecting portion 311 , and a third avoidance groove 318 is opened upward at the top of the threaded hole 317 , and the third avoidance groove 318 extends into the connecting seat 31 .

[0062] In the present embodiment, the gap grooves 312 are provided with two arranged perpendicularly, and the gap grooves 312 pass through the threaded hole .07, and the annular grooves 313 are provided with two. The two annular grooves 313 are arranged along the axial spacing of the screw connecting part 311, and correspondingly, the first O-rings 33 are provided with two; the guide shaft 34 and the guide hole seat 314 are provided with two symmetrically arranged, so that the sliding of the connecting seat 31 is smoother, and the plunger rod 32 cannot rotate and can only enter and exit the cavity 21 vertically along the straight direction, so that the volume of the liquid displaced by the plunger rod 32 entering the cavity 21 is a standard cylindrical shape, and the actual liquid displacement volume converted by the displacement of the plunger rod 32 is accurate. Without this structure, the posture of the plunger rod 32 when entering the cavity 21 may rotate and tilt, but the calculation is still based on the vertical entry calculation, and the actual volume of the liquid displaced by the plunger rod 32 will have a greater deviation from the theoretical calculated volume; and the connecting seat 31 is made of plastic material, so that the screw connecting part 311 can undergo a large elastic deformation.

[0063] The working principle of this embodiment is described in detail:

[0064] The stepper motor 11 is used as a driving element to drive the screw rod 13 to rotate. The screw rod 13 and the screw rod connecting part 311 are combined into a screw rod 13 nut pair. When the screw rod 13 rotates forward and backward, since there are two guide hole seats 314 on the connecting seat 31 that are sleeved on the guide shaft 34, the connecting seat 31 cannot rotate but moves linearly up and down. The connecting seat 31 and the plunger rod 32 are connected as a whole. When the connecting seat 31 moves up and down, the plunger rod 32 connected together will be driven to move up and down together. The up and down movement of the plunger rod 32 will cause the volume occupied by the plunger rod 32 in the movable groove 211 of the cavity 21 to change, so that the liquid in the cavity 21 is sucked into or discharged from the cavity 21, completing the function of quantitative pipetting.

[0065] The design emphasis of the present invention is:

[0066] The main point is that a clearance groove penetrating the screw rod connection part is opened in the radial direction of the screw rod connection part, an annular groove is concavely arranged in the circumferential direction of the screw rod connection part, and a first O-ring for pressing the screw rod connection part against the screw rod is sleeved in the annular groove. The arrangement of the first O-ring and the clearance groove enables the screw rod connection part to press against the screw thread of the screw rod. In this case, the return stroke difference of the screw rod nut pair can be greatly reduced. At the same time, when the teeth of the screw rod connection part are worn, the clamping force of the first O-ring can also make the screw rod connection part press against the screw thread of the screw rod, thereby playing a role in wear compensation. The structural design The design is ingenious, and a guide shaft and a guide hole seat are provided, which limit the shaking of the connecting seat when it moves up and down, and then limit the shaking of the plunger rod, so that the plunger rod maintains a vertical posture when entering and exiting the cavity, reducing the error between the theoretical calculated pipetting volume and the actual pipetting volume, and improving the pipetting accuracy of the plunger pump; and the cavity is fixed to the end of the support frame away from the motor by screws passing through the spacer ring. The cavity can fix the guide shaft in the first avoidance groove, so that the guide shaft can provide positioning for the installation of the pump head assembly, which is convenient for the assembly of the pump head assembly and the fixing of the guide shaft.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-precision plunger pump with backlash elimination function, comprising a control component, a pump head component and a plunger component; characterized in that: The control assembly includes a motor and a support frame arranged on the motor, the motor is connected to a screw rod, the support frame is provided with a through slot extending vertically, and the screw rod is located in the through slot; The pump head assembly includes a cavity and a spacer ring, wherein a movable groove for the plunger rod to move is arranged in the cavity, the spacer ring covers the movable groove and the through groove and is provided with an escape hole for the plunger rod to pass through, and the cavity is fixed to the end of the support frame away from the motor by screws passing through the spacer ring; The plunger assembly can be movably arranged in the through groove, and the plunger assembly includes a connecting seat and a plunger rod, the plunger rod is connected to one end of the connecting seat close to the spacer ring, and the end of the plunger rod away from the connecting seat extends into the movable groove, and the end of the connecting seat away from the spacer ring is provided with a screw connecting part, and the screw connecting part is connected to the screw, and a clearance groove that penetrates the screw connecting part is radially opened on the screw connecting part, and an annular groove is circumferentially recessed on the screw connecting part, and a first O-ring for pressing the screw connecting part against the screw is sleeved in the annular groove, and a guide hole seat is provided on the side of the connecting seat, and a guide shaft is passed through the guide hole seat, and a first avoidance groove for the guide hole seat to movably avoid is provided on the side of the through groove, and the end of the guide shaft away from the motor passes through the spacer ring and abuts against the bottom of the cavity, and the cavity can fix the guide shaft in the first avoidance groove.

2. A high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: The control component also includes a photoelectric switch, a shielding piece cooperating with the photoelectric switch is arranged on the side of the connecting seat, a second avoidance groove is opened on the side of the through groove for the shielding piece to move around, and the photoelectric switch is arranged on the support seat and extends into the second avoidance groove.

3. A high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: A sealing assembly is arranged between the outer periphery of the plunger rod and the movable groove, and a first groove is concavely arranged upwardly at the bottom of the cavity. Correspondingly, a protrusion matching the first groove is convexly arranged at the top of the spacer ring, and the protrusion abuts against the first groove and fixes the sealing assembly to the cavity.

4. A high-precision plunger pump with backlash elimination function according to claim 3, characterized in that: A second groove is formed on the top of the support frame at the outer periphery of the through groove. Correspondingly, an annular convex portion matching the second groove is convexly formed on the bottom of the spacer ring. The bottom of the annular convex portion abuts against the second groove. A third groove is concave upwardly in the annular convex portion. The end of the connecting seat close to the spacer ring can extend into the third groove.

5. A high-precision plunger pump with backlash elimination function according to claim 4, characterized in that: The sealing assembly includes a second O-ring, a sealing ring, a first sealing gasket and a second sealing gasket which are arranged in sequence. The sealing ring has a through hole. An annular extension portion extends from the end of the sealing ring away from the spacer ring. The second O-ring is sleeved outside the annular extension portion. A fourth groove is recessed on the top of the annular convex portion. The first sealing gasket and the second sealing gasket are located in the fourth groove.

6. A high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: The outer circumference of the spacer ring is aligned with the outer circumference of the cavity.

7. A high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: A fifth groove is recessed at one end of the connecting seat close to the spacer ring, and the plunger rod is inserted into the fifth groove. An annular groove is provided on the outer periphery of the plunger rod, and a glue injection hole connected to the annular groove is provided on the outer periphery of the connecting seat. The plunger rod is fixed in the fifth groove by structural glue.

8. The high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: The bottom of the first avoidance groove is recessed downwardly to form a sixth groove, the guide shaft is inserted into the sixth groove, and the cavity can fix the guide shaft in the sixth groove.

9. The high-precision plunger pump with backlash elimination function according to claim 1, characterized in that: A threaded hole matching the screw rod is arranged in the screw rod connecting part, and a third avoidance groove is opened upwardly at the top of the threaded hole, and the third avoidance groove extends into the connecting seat.

10. A high-precision plunger pump with backlash elimination function according to claim 9, characterized in that: The two clearance grooves are arranged to intersect each other vertically, and the clearance groove passes through the threaded hole. The two annular grooves are arranged at an axial distance along the screw connecting part. Correspondingly, two first O-rings are provided.

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