Pipette and pipetting method

Abstract

The application discloses a pipette and a pipetting method. The pipette comprises a housing, a driving mechanism, a plunger rod, a first sleeve and a second sleeve. The first sleeve is connected with the housing and has a sliding cavity. At least the front end of the plunger rod is inserted into the sliding cavity of the first sleeve and is in sliding fit with the first sleeve. The driving mechanism has a transmission member, and the driving mechanism is installed on the housing. The transmission member is directly or indirectly connected with the rear end of the plunger rod and is used for driving the plunger rod to move along the longitudinal direction of the plunger rod. The second sleeve is sleeved outside the first sleeve and is in sliding fit with the first sleeve. The front end of the second sleeve has an ejection part, and the rear end of the second sleeve corresponds to the transmission member. The application can accurately and reliably perform the operation of withdrawing the gun head and does not need to increase special operation steps.

Description

Technical Field

[0001] This invention belongs to the field of experimental or detection technology, specifically relating to pipettes and pipetting methods. Background Technology

[0002] A pipette is a device used for the quantitative transfer of liquids, usually in conjunction with a three-dimensional moving mechanism to quantitatively aspirate and transfer liquids.

[0003] In many applications, especially in biological applications such as micropipettes, such as pretreatment and filling equipment for chemiluminescence analyzers and nucleic acid extractors, disposable pipette tips are usually required due to the hazardous nature of the liquid being pipetted, its difficulty in cleaning, or its convenience.

[0004] Currently, the market for pipettes is almost entirely dominated by imported products. The main body of these pipettes is made of stainless steel, and the internal movement is driven by a gear and rack. The internal structure of existing pipettes means that the tip retraction stroke is relatively short, requiring the spring force to retract the tip. If the tip size is not consistent, there is a high probability that the tip will not be able to retract.

[0005] Existing pipettes often fail to completely remove the pipette tip, resulting in unreliable operation and affecting pipetting efficiency, as well as posing safety hazards during operation. Summary of the Invention

[0006] The purpose of this invention is to provide a pipette and a pipetting method. This invention can accurately and reliably perform pipette tip withdrawal without requiring any special operating steps.

[0007] This invention provides a pipette, comprising: a housing, a drive mechanism, a stopper rod, a first sleeve, and a second sleeve;

[0008] The first sleeve is connected to the housing and has a sliding cavity inside;

[0009] At least the front end portion of the plug rod is inserted into the sliding cavity of the first sleeve and slides in cooperation with the first sleeve;

[0010] The drive mechanism has a transmission component, which is mounted on the housing. The transmission component is directly or indirectly connected to the rear end of the piston rod, and is used to drive the piston rod to move along its longitudinal direction.

[0011] The second sleeve is fitted over the first sleeve and slides in conjunction with the first sleeve. The front end of the second sleeve has an ejector portion, and the rear end of the second sleeve corresponds to the transmission component.

[0012] In one embodiment, the transmission component includes a moving block, a push rod, and an elastic element;

[0013] The rear end of the stopcock is connected to the moving block;

[0014] The housing has a first through hole, the push rod passes through the first through hole and slides in the first through hole, and an elastic element is provided between the housing and the push rod;

[0015] The lower end of the push rod corresponds to the upper end of the second sleeve.

[0016] In one embodiment, the drive mechanism includes a motor, a lead screw, and a lead nut;

[0017] The output shaft of the motor is connected to the lead screw, and the lead screw is engaged with the lead nut;

[0018] The movable block is fixedly connected to the nut;

[0019] The housing is provided with a guide rail, and the moving block slides in conjunction with the guide rail.

[0020] In one embodiment, a positioning strip integrally formed with the main body is provided on the housing, the guide rail is fixed on the positioning strip and the guide rail is arranged in the same direction as the positioning strip; the side of the moving block is a slider, which slides in cooperation with the guide rail.

[0021] In one embodiment, the plug rod includes a main rod and a connector. The main rod is made of ceramic material, and the connector is fixed to the rear end of the main rod. A first groove is provided on the outer wall of the rear end of the main rod, and an insertion hole is provided in the middle of the connector. A second groove is provided on the inner wall of the insertion hole of the connector. The first groove and the second groove correspond to each other, and a positioning rubber ring is provided between the first groove and the second groove.

[0022] In one embodiment, a sealing seat is provided at the rear end of the first sleeve, and a receiving groove is provided on the inner wall of the sealing seat, and a sealing ring is provided in the receiving groove.

[0023] The sealing ring has a first end and a second end along the axial direction;

[0024] The inner diameter of the first end of the sealing ring is larger than the inner diameter of the second end. The inner wall of the second end of the sealing ring is attached to the outer wall of the plug rod. There is a fitting gap between the inner wall of the first end of the sealing ring and the outer wall of the plug rod. A sealing ring is provided between the outer wall of the sealing ring and the sealing seat.

[0025] In one embodiment, the closure seat includes a first seat body and a second seat body, the first seat body and the second seat body being engaged together, and the receiving groove being formed between them;

[0026] The sealing rings are two in number, including a first sealing ring and a second sealing ring; a third groove and a fourth groove are provided on the outer wall of the sealing ring, the third groove is close to the first end of the sealing ring, the fourth groove is close to the second end of the sealing ring, and the depth of the third groove in the circumferential direction is less than the depth of the fourth groove in the circumferential direction.

[0027] The first sealing ring is placed in the third groove, and the second sealing ring is placed in the fourth groove. The diameter of the first sealing ring is smaller than the diameter of the second sealing ring.

[0028] The sealing ring extends from the fourth groove toward its second end to form a cylindrical end, the outer diameter of which gradually decreases toward the outward end.

[0029] In one embodiment, the stopper rod has the same diameter at least in the middle section region;

[0030] The rear end of the first sleeve is provided with a sealing seat, the inner wall of the sealing seat is provided with a receiving groove, and a sealing ring is provided in the receiving groove;

[0031] A tail cavity is formed between the front end region of the sealing ring on the sealing seat and the plug rod, and a vent pipe is provided on the sealing seat, which communicates with the tail cavity.

[0032] In one embodiment, a first protrusion and a second protrusion are provided at the front end of the first sleeve, and a third protrusion is provided at the front end of the second sleeve; the first protrusion and the second protrusion are spaced apart along the axial direction of the first sleeve, and the first protrusion and the second protrusion protrude outward in the circumferential direction relative to the outer wall of the main body portion of the first sleeve at that location, and the third protrusion protrudes inward in the circumferential direction relative to the inner wall of the main body portion of the second sleeve at that location.

[0033] The present invention also provides a pipetting method, the method comprising the following steps:

[0034] The front end of the first sleeve is aligned with the rear end of the gun head, and the rear end of the gun head is fitted into the front end of the first sleeve.

[0035] The rear end of the nozzle is engaged with the front end of the first sleeve;

[0036] The pipette tip is guided to the position where the liquid is to be transferred through the first tubing;

[0037] The drive mechanism drives the plunger rod to move along its axial direction to its rear end to draw liquid through its transmission part, and drives the plunger rod to move along its axial direction to its front end to discharge liquid, thus completing the liquid transfer operation.

[0038] The drive mechanism continues to move forward, pushing the second sleeve towards its front end. The front end of the second sleeve abuts against the rear end of the gun head, causing the gun head to gradually detach from the first sleeve, thus completing the removal of the gun head.

[0039] The technical solution provided by this invention has the following advantages and effects:

[0040] In this invention, the first sleeve is connected to the housing, and at least the front end of the stopper rod is inserted into the sliding cavity of the first sleeve to achieve liquid aspiration and dispensing, thus realizing the function of pipetting. Disposable pipette tips are required during pipetting. In this invention, the process of attaching and removing the pipette tip is as follows: the pipette moves forward as a whole, the front end of the first sleeve is inserted into the rear end of the pipette tip, and the pipette tip and the first sleeve are locked together by a certain amount of interference fit. The driving device drives the stopper rod to move backward through the transmission component, aspirating liquid through the pipette tip. The driving device then drives the stopper rod to move forward through the transmission component, dispensing liquid through the pipette tip. After dispensing, the driving device continues to move forward and presses against the rear end of the pipette tip through the second sleeve, withdrawing the pipette tip from the front end of the first sleeve. The removal operation of the pipette tip is very reliable and accurate, and does not require any extra actions from the mechanism; the removal of the pipette tip is smooth. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall structure of the pipette described in this invention;

[0042] Figure 2 This is an anatomical view of the pipette described in this invention after the first panel has been removed.

[0043] Figure 3 This is a structural diagram of the frame in the pipette of the present invention;

[0044] Figure 4 This is an exploded view of the pipette described in this invention.

[0045] Figure 5 This is an exploded view of a partial structure of the pipette described in this invention.

[0046] Figure 6 This is an exploded view of the lower part of the pipette structure described in this invention.

[0047] Figure 7 This is a cross-sectional view of a partial structure of the lower part of the pipette described in this invention;

[0048] Figure 8 for Figure 7 A magnified view of a portion of the image;

[0049] Figure 9 An enlarged view of the moving part;

[0050] Figure 10An enlarged view of the first side of the pusher component;

[0051] Figure 11 An enlarged view of the second side of the pusher component;

[0052] Figure 12 This is an enlarged view of the stop;

[0053] Figure 13 This is a schematic diagram of the process of removing the pipette tip from the pipette described in this invention;

[0054] Explanation of reference numerals in the attached figures:

[0055] 10. Housing; 11. Frame; 111. Positioning strip; 112. Guide rail; 113. Left frame; 114. Right frame; 115. Top frame; 116. Bottom frame; 118. First through hole; 119. Second through hole; 12. First panel; 13. Second panel; 14. Pressure plate; 15. Ribbon cable; 16. Circuit board; 17. Upper limit stage; 18. Lower limit stage.

[0056] 20. Drive mechanism; 21. Motor; 22. Lead screw; 23. Nut; 231. Cylindrical part; 232. Plate-shaped connecting part; 24. Moving block; 241. Slider; 242. Main body; 2421. Mounting hole; 2422. Notch; 24221. Step; 24222. Flange; 24223. Arc-shaped clearance notch; 2423. Side end face; 243. Side plate.

[0057] 25. Pushing component; 251. Rod; 252. Connecting plate; 2521. Protruding strip; 2522. Relief groove.

[0058] 26. Push rod; 261. Rod body; 262. Pressure plate; 263. Stop; 2631. Center hole; 2632. Guide bar; 2633. Connecting piece; 2634. Guide piece.

[0059] 27. Elastic components,

[0060] 30. Plug rod; 31. Main rod; 311. First groove; 32. Connector; 321. Second groove; 322. Insertion hole; 323. Vent hole; 33. Positioning rubber ring; 34. Annular groove.

[0061] 40. First sleeve; 41. Sliding cavity; 42. Sealing seat; 421. First seat body; 4211. Guide groove; 422. Second seat body; 423. Receiving groove; 424. Sealing ring; 425. Fitting clearance; 426. Third groove; 427. Fourth groove; 428. Cylindrical end; 429. Third through hole; 43. First sealing ring; 44. Second sealing ring; 45. Tail cavity; 46. Vent pipe; 471. First protrusion; 472. Second protrusion; 473. Fourth protrusion; 474. Fifth protrusion; 475. Annular groove; 481. Rear end protrusion ring; 482. Third sealing ring.

[0062] 50. Second sleeve; 51. Ejector part; 52. Third protrusion part; 53. Upper sleeve.

[0063] 60. Fixing hole

[0064] 70. Gun tip. Detailed Implementation

[0065] To facilitate understanding of the present invention, specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0066] Unless otherwise specified or defined, the terms "first," "second," etc., used in this document are for distinguishing names only and do not represent a specific number or order.

[0067] Unless otherwise stated or defined, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0068] It should be noted that in this article, "fixed to" or "connected to" can mean directly fixed to or connected to a component, or indirectly fixed to or connected to a component.

[0069] like Figures 1 to 13 As shown, the pipette includes: a housing 10, a drive mechanism 20, a stopper rod 30, a first sleeve 40, and a second sleeve 50;

[0070] The first sleeve 40 is connected to the housing 10 and has a sliding cavity 41 inside;

[0071] The front end of the plug rod 30 is inserted into the sliding cavity 41 of the first sleeve 40 and slides in cooperation with the first sleeve 40.

[0072] The drive mechanism 20 has a transmission component. The drive mechanism 20 is mounted on the housing 10. Its transmission component is directly or indirectly connected to the rear end of the stopper rod 30 and is used to drive the stopper rod 30 to move in its longitudinal direction. In this embodiment, the transmission component includes components such as a nut 23, a moving block 24, and a push rod 26. The structure of these components will be described in detail later.

[0073] The second sleeve 50 is sleeved outside the first sleeve 40 and slides in cooperation with the first sleeve 40. The front end of the second sleeve 50 has an ejector part 51, and the rear end of the second sleeve 50 corresponds to the transmission member. When the gun head 70 is retracted, the ejector part 51 abuts against the rear end of the gun head 70.

[0074] Please focus on combining Figures 1 to 4 As shown, the housing 10 provides support for the entire pipette. In use, the housing 10 is fixed to a three-dimensional moving robotic arm and moved by the robotic arm. The housing 10 includes a frame 11, a first panel 12, and a second panel 13. The frame 11 includes a left side frame 113, a right side frame 114, a top side frame 115, and a bottom side frame 116, which are integrally formed. The first panel 12 and the second panel 13 are respectively connected to the front and rear surfaces of the frame 11, forming a mounting cavity between the first panel 12 and the second panel 13. The drive mechanism 20 and the circuit board 16 are installed in this mounting cavity. The circuit board 16 is used to control the movement of the drive mechanism, etc.

[0075] The drive mechanism 20 includes a motor 21, a lead screw 22, and a lead screw nut 23; the transmission components include a moving block 24, a push rod 26, and an elastic element 27; please pay close attention to the following: Figures 2 to 4 As shown, the output shaft of the motor 21 is connected to the lead screw 22. When the motor 21 is working, it drives the lead screw 22 to rotate. The lead screw 22 engages with the lead nut 23, and the moving block 24 is fixedly connected to the lead nut 23. Since the lead nut 23 is threadedly engaged with the lead screw 22, when the lead screw 22 rotates, the lead nut 23 translates along its axial direction. This structure can convert the rotational motion of the motor 21 into the translational motion of the lead nut 23. The motor 21 can be a stepper motor to more accurately control the stroke of the lead nut 23. In this embodiment, the lead screw 22 can be a ball screw. When the motor 21 is working, the lead screw 22 drives the lead nut 23 to translate, which in turn drives the moving block 24 to move up and down. When the output shaft of the motor 21 rotates in the forward direction, the moving block 24 translates upward; when the output shaft of the motor 21 rotates in the reverse direction, the moving block 24 translates downward. By changing the rotational direction of the output shaft of the motor 21, the direction of the up and down translation of the moving block 24 can be changed.

[0076] A positioning strip 111 integrally formed with the main body is provided on the frame 11. The guide rail 112 is fixed to the positioning strip 111, and the guide rail 112 is arranged in the same direction as the positioning strip 111. The side of the moving block 24 is a slider 241, which slides in engagement with the guide rail 112. The slider 241 slides in engagement with the guide rail 112, and the guide rail 112 ensures the straightness of the moving block 24 during translation. An upper limit platform 17 and a lower limit platform 18 are provided on the upper part of the positioning strip 111, which can limit the vertical position of the slider 241.

[0077] Please focus on combining Figure 2 , Figure 4 , Figure 5 , Figure 6 and Figure 7As shown, the plug rod 30 includes a main rod 31 and a connector 32. The main rod 31 is made of ceramic material, and the connector 32 is fixed to the rear end of the main rod 31. A first groove 311 is provided on the outer wall of the rear end of the main rod 31. The connector 32 has an insertion hole 322 in the middle, and a second groove 321 is provided on the inner wall of the insertion hole 322 of the connector 32. The first groove 311 and the second groove 321 correspond to each other, and a positioning rubber ring 33 is provided between the first groove 311 and the second groove 321. During the pipetting process, liquid retention can cause corrosion and adhesion at the mating parts between the stopper rod 30 and the first sleeve 40. Therefore, the main rod 31 of the stopper rod 30 is made of ceramic material, which can reduce the impact of chemical liquids on the fitting accuracy between the stopper rod 30 and the first sleeve 40, and reduce corrosion and adhesion between them. Furthermore, the stopper rod 30 adopts a split structure, and the connector 32 can be made of materials such as stainless steel. This structure facilitates the connection and fixation of the rear end of the stopper rod 30 and avoids damage to the stress-bearing parts at the rear end of the stopper rod 30, thus affecting its service life (ceramic materials are prone to damage and breakage). To achieve the connection between the ceramic main rod 31 and the stainless steel connector 32, the rear end of the main rod 31 is inserted into the insertion hole 322 at the front end of the connector 32, and a first groove 31 is provided on the outer wall of the rear end of the main rod 31. 1. A second groove 321 is provided on the inner wall of the insertion hole 322 of the connector 32. The positioning rubber ring 33 is engaged between the first groove 311 and the second groove 321, which connects the main rod 31 and the connector 32. The positioning rubber ring 33 has a buffering effect, which can achieve the purpose of soft connection between the main rod 31 and the connector 32, so as to reduce the impact force on the ceramic material main rod 31 during the translation of the slider 241, further avoid damage to the main rod 31, and improve its service life. During the installation process, since the positioning rubber ring 33 has a certain sealing effect, in order to solve the air venting problem when the rear end of the main rod 31 is inserted into the insertion hole 322 of the connector 32, an exhaust hole 323 is provided on the connector 32. When the main rod 31 and the connector 32 are connected and installed, the air inside the connector 32 can be vented through the exhaust hole 323.

[0078] The rear end of the connector 32 is in the shape of an "I" and its outer wall is provided with an annular groove 34. The plug rod 30 can be fixed through the annular groove 34. The fixing structure of the plug rod 30 is further described below:

[0079] Please focus on combining Figure 5 , Figure 9 , Figure 10 , Figure 11As shown, the movable block 24 includes a main board body 242 and a side plate body 243 located on the first side of the main board body 242. The main board body 242 is horizontal and the side plate body 243 is vertical. The main board body 242 is provided with mounting holes 2421 along the vertical direction. The nut 23 has a cylindrical part 231 and a plate-shaped connecting part 232. The cylindrical part 231 of the nut 23 is fitted into the mounting hole 2421 of the movable block 24. After the fixing screw (not shown in the figure) passes through the fixing hole 60, it connects the plate-shaped connecting part 232 of the nut 23 to the main board body 242 of the movable block 24. After the fixing screw (not shown in the figure) passes through the fixing hole 60, it connects the side plate body 243 on the first side of the movable block 24 to the slider 241, and the slider 241 cooperates with the guide rail 112.

[0080] Please focus on combining Figure 5 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown, a notch 2422 is provided on the second side of the main body 242 of the movable block 24, opposite to the direction of the first side. The notch of the notch 2422 faces the second side. The upper part of the notch 2422 is larger than the lower part, forming a step 24221. A flange 24222 is formed below the step 24221. The annular groove 34 of the connector 32 of the plug rod 30 is engaged above the notch 2422, and the annular groove 34 of the connector 32 is engaged at the flange 24222. At this time, after the fixing screw (not shown in the figure) passes through the fixing hole 60, the pusher 25 is fixedly connected to the main body 242 of the movable block 24, thereby closing the notch of the notch 2422 and engaging the connector 32 of the plug rod 30 at the notch 2422, thus realizing the connection between the rear end of the plug rod 30 and the movable block 24. An arc-shaped clearance notch 24223 is provided on the side plate 243 near the main plate 242 to facilitate the passage of the nut 23.

[0081] Below the pusher 25 is a rod 251. A connecting plate 252 is provided on the side near the main body 242. The connecting plate 252 has a fixing hole 60 to facilitate fixing to the main body 242 with fixing screws. A protrusion 2521 is provided on the side of the connecting plate 252 near the main body 242. The protrusion 2521 corresponds to the notch. When the connecting plate 252 is fixed to the fixing hole 60 on the side end face 2423 of the main body 242, the protrusion 2521 is stuck in the notch and can prevent the pusher 25 from tilting. This structure can be fixed with a single fixing screw and avoids the pusher 25 from shifting relative to the main body 242. An arc-shaped relief groove 2522 is provided on the side of the connecting plate 252 away from the main body 242 to facilitate the fixing of the fixing screw.

[0082] The push rod 26 includes a rod body 261, with a pressure plate 262 at the lower end and a stop 263 at the upper end. The stop 263 has a central hole 2631. An elastic element 27 (i.e., a helical spring) is sleeved on the rod body 261, and the upper end of the rod body 261 is inserted into the central hole 2631 of the stop 263 and fixed therein. A first through hole 118 and a second through hole 119 are provided on the lower frame 116 of the housing 10. The push rod 26 passes through the first through hole 118 and slides in cooperation with it. The elastic element 27 is located between the housing 10 and the push rod 26. The rear end of the stop rod 30 is connected to the moving block 24, passes through the second through hole 119, and extends out of the housing 10.

[0083] An upper sleeve 53 is provided at the upper end of the second sleeve 50. The pressure plate 262 at the lower end of the rod body 261 of the push rod 26 corresponds to the upper sleeve 53 at the upper end of the second sleeve 50. When the push rod 26 moves down, the pressure plate 262 at its lower end pushes the upper sleeve 53 at the upper end of the second sleeve 50, thereby pushing the second sleeve 50 down through the upper sleeve 53.

[0084] Please focus on combining Figure 4 , Figure 6 , Figure 7 and Figure 8As shown, a sealing seat 42 is provided at the rear end of the first sleeve 40. The sealing seat 42 includes a first seat body 421 and a second seat body 422. The first seat body 421 and the second seat body 422 are engaged and form the receiving groove 423 between them. The sealing seat 42 is fixedly connected to the housing 10 through the first seat body 421. A third through hole 429 is provided at the center of the first seat body 421 to facilitate the passage of the plug rod 30. A sealing ring 424 is provided within the receiving groove 423. The sealing ring 424 has a first end and a second end along the axial direction. The inner diameter of the first end of the sealing ring 424 is larger than the inner diameter of the second end. The inner wall of the second end of the sealing ring 424 is attached to the outer wall of the plug rod 30. There is a fitting gap 425 between the inner wall of the first end of the sealing ring 424 and the outer wall of the plug rod 30. A sealing ring is provided between the outer wall of the sealing ring 424 and the sealing seat 42. Specifically, there are two sealing rings, including a first sealing ring 43 and a second sealing ring 44. A third groove 426 and a fourth groove 42 are provided on the outer wall of the sealing ring 424. 7. The third groove 426 is close to the first end of the sealing ring 424, and the fourth groove 427 is close to the second end of the sealing ring 424. The depth of the third groove 426 in the circumferential direction is less than the depth of the fourth groove 427 in the circumferential direction. The first sealing ring 43 is placed in the third groove 426, and the second sealing ring 44 is placed in the fourth groove 427. The diameter of the first sealing ring 43 is less than the diameter of the second sealing ring 44. The sealing ring 424 extends from the fourth groove 427 towards its second end to form a cylindrical end 428, the outer diameter of which gradually decreases towards the outward end. A rear end protrusion ring 481 is provided at the rear end of the first sleeve 40, and a third sealing ring 482 is fitted on the rear end protrusion ring 481. The third sealing ring 482 achieves the seal between the rear end of the first sleeve 40 and the sealing seat 42.

[0085] In this embodiment, the inner hole of the sealing ring 424 adopts an inwardly inclined structure, and the bottom surface can be slightly interference-fitted with the plug rod 30. There is a fitting gap between the inner wall of the first end of the sealing ring 424 and the outer wall of the plug rod 30. This inclined surface design reduces the contact area between the sealing ring 424 and the plug rod 30, reduces the friction between the contact surfaces, and effectively extends the service life. Meanwhile, the lower edge of the sealing ring 424 is tightly wrapped by the second sealing ring 44. With the accumulation of movement over a long period of time, there may be slight wear at the contact point between the lower edge of the sealing ring 424 and the sealing ring 44. Since the outer diameter of the cylindrical end 428 gradually decreases towards the outward end, the second sealing ring 44 tends to move downwards. The lower side of the second sealing ring 44 is tightly against the inner wall of the second seat 422. Furthermore, due to the inward elastic force of the second sealing ring 44, the sealing upper sleeve 612 is effectively ensured to always fit seamlessly with the plug rod 30. In addition, the sealing ring 424 is made of a high-molecular polymer plastic, which has wear-resistant, self-lubricating, elastic, and easy-to-process properties, thus ensuring the airtightness of the inner cavity of the pipette syringe barrel 617. A first elastic collar 613 is also provided between the sealing ring 424 and the sealing seat 42, further ensuring gas sealing.

[0086] Except for a small portion at the front end, the plug rod 30 has a uniform diameter for most of its length. A tail cavity 45 is formed between the front end of the sealing ring 424 on the sealing seat 42 and the plug rod 30. A vent pipe 46 is provided on the sealing seat 42, and the vent pipe 46 communicates with the tail cavity 45. When the plug rod 30 moves up and down, the volume of air in the tail cavity 45 changes accordingly. By connecting the vent pipe 46 to a detection element, the amount of liquid being absorbed or discharged can be determined by observing the change in the volume of the tail cavity 45 when the plug rod 30 moves.

[0087] A guide groove 4211 is provided on the first seat 421. A guide strip 2632 is provided on the first side of the stop 263. The guide strip 2632 is inserted into the guide groove 4211 and cooperates with the guide groove 4211. When the stop 263 slides up and down, the guide strip 2632 on its side plays a guiding role. A connecting piece 2633 is provided on the second side of the stop 263. The end of the connecting piece 2633 near the second side is bent to form a guide piece 2634. The guide piece 2634 is close to the inner side of the frame 11. When the stop 263 slides up and down, the frame 11 plays a certain limiting role for the stop 263.

[0088] A first protrusion 471, a second protrusion 472, a fourth protrusion 473, and a fifth protrusion 474 are provided at the front end of the first sleeve 40, and a third protrusion 52 is provided at the front end of the second sleeve 50. The first protrusion 471, the second protrusion 472, the fourth protrusion 473, and the fifth protrusion 474 are arranged sequentially at intervals along the axial direction of the first sleeve 40. Specifically, an annular groove 475 is formed at the front end of the first sleeve 40, and the first [protrusion 471] is formed at the rear end and the front end of the annular groove 475, respectively. The first protrusion 471 and the second protrusion 472 protrude outward in the circumferential direction relative to the outer wall of the front end and / or rear end of the main body portion of the first sleeve 40 at that location. The fourth protrusion 473 is located at the front end of the second protrusion 472, and the fifth protrusion 474 is located at the front end of the fourth protrusion 473, and the diameter of the fourth protrusion 473 is larger than the diameter of the fifth protrusion 474. The third protrusion 52 protrudes inward in the circumferential direction relative to the inner wall of the front end and / or rear end of the main body portion of the second sleeve 50 at that location. In this embodiment, the processing method of the third protrusion 52 is as follows: firstly, an "I"-shaped slot is opened at the front end of the second sleeve 50, and two opposing corner pieces are formed at the front end of the second sleeve 50. When the first sleeve 40 is inserted into the second sleeve 50 and the corner pieces are located between the first protrusion 471 and the second protrusion 472, the two corner pieces are pressed into the space between the first protrusion 471 and the second protrusion 472, and the two corner pieces form the third protrusion 52. At this time, the third protrusion 52 can only move in the area between the first protrusion 471 and the second protrusion 472.

[0089] Please focus on combining Figure 13 As shown, the usage process of the pipette described in this embodiment of the invention is as follows:

[0090] The three-dimensional moving robotic arm moves the pipette described in this embodiment downwards, aligning the first sleeve 40 with the pipette tip 70. The robotic arm continues to move the pipette downwards, inserting the front end of the first sleeve 40 into the pipette tip 70. There is a certain degree of interference fit between the pipette tip 70 and the fifth protrusion 474 of the first sleeve 40. The rear end of the pipette tip 70 is limited by the fourth protrusion 474. The state at this time is as follows: Figure 12 As shown on the left side; before the gun head 70 is taken out, the elastic element 27 retracts under pressure. Due to the action of the elastic element 27, the impact force of the gun head 70 on the first sleeve 40 is buffered, making the force of the gun head 70 on the rear mechanism more gentle, especially reducing the impact on the first sleeve 40, motor 21, and three-dimensional moving robotic arm.

[0091] The three-dimensional moving robotic arm drives the pipette described in this embodiment to move, and carries the pipette tip 70 to the position where the liquid is to be pipetted;

[0092] The motor 21 rotates in the forward direction, and the nut 23 drives the stopper rod 30 to move upward through the moving block 24 to draw liquid;

[0093] After the liquid is aspirated, the three-dimensional moving robotic arm moves the pipette described in this embodiment to the discharge position;

[0094] Motor 21 rotates in the opposite direction, and nut 23 drives stopper rod 30 to move down through moving block 24 to drain liquid;

[0095] Motor 21 continues to rotate in the opposite direction, nut 23 continues to move downward, and push rod 26 pushes second sleeve 50 downward. The front end of second sleeve 50 abuts against the rear end of gun head 70, causing gun head 70 to gradually disengage from first sleeve 40, completing the removal of gun head 70. The state at this time is as follows: Figure 12 As shown on the right.

[0096] The above embodiments are not an exhaustive list based on the present invention, and there may be many other embodiments not listed. Any substitutions and improvements made without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A pipette, characterized in that, include: Housing, drive mechanism, piston rod, first sleeve, second sleeve; The first sleeve is connected to the housing and has a sliding cavity inside; At least the front end portion of the plug rod is inserted into the sliding cavity of the first sleeve and slides in cooperation with the first sleeve; The drive mechanism has a transmission component, which is mounted on the housing. The transmission component is directly or indirectly connected to the rear end of the piston rod, and is used to drive the piston rod to move along its longitudinal direction. The second sleeve is fitted outside the first sleeve and slides in conjunction with the first sleeve. The front end of the second sleeve has an ejector part, and the rear end of the second sleeve corresponds to the transmission component. The rear end of the first sleeve is provided with a sealing seat, the inner wall of the sealing seat is provided with a receiving groove, and a sealing ring is provided in the receiving groove; The sealing ring has a first end and a second end along the axial direction; The inner diameter of the first end of the sealing ring is larger than the inner diameter of the second end. The inner wall of the second end of the sealing ring is attached to the outer wall of the plug rod. There is a fitting gap between the inner wall of the first end of the sealing ring and the outer wall of the plug rod. A sealing ring is provided between the outer wall of the sealing ring and the sealing seat. The closure seat includes a first seat body and a second seat body, the first seat body and the second seat body are engaged and the receiving groove is formed between them; The sealing rings are two in number, including a first sealing ring and a second sealing ring; a third groove and a fourth groove are provided on the outer wall of the sealing ring, the third groove is close to the first end of the sealing ring, the fourth groove is close to the second end of the sealing ring, and the depth of the third groove in the circumferential direction is less than the depth of the fourth groove in the circumferential direction. The first sealing ring is placed in the third groove, and the second sealing ring is placed in the fourth groove. The diameter of the first sealing ring is smaller than the diameter of the second sealing ring. The sealing ring extends towards its second end at the fourth groove and forms a cylindrical end, the outer diameter of which gradually decreases towards the outward end. As the outer diameter of the cylindrical end gradually decreases towards the outward end, the second sealing ring tends to move downwards, and the lower side of the second sealing ring is in close contact with the inner wall of the second seat.

2. The pipette as described in claim 1, characterized in that, The transmission component includes a moving block, a push rod, and an elastic element; The rear end of the stopcock is connected to the moving block; The housing has a first through hole, the push rod passes through the first through hole and slides in the first through hole, and an elastic element is provided between the housing and the push rod; The lower end of the push rod corresponds to the upper end of the second sleeve.

3. The pipette as described in claim 2, characterized in that, The drive mechanism includes a motor, a lead screw, and a lead nut; The output shaft of the motor is connected to the lead screw, and the lead screw is engaged with the lead nut; The movable block is fixedly connected to the nut; The housing is provided with a guide rail, and the moving block slides in conjunction with the guide rail.

4. The pipette as described in claim 3, characterized in that, The housing is provided with a positioning strip integrally formed with the main body, the guide rail is fixed on the positioning strip and the guide rail is arranged in the same direction as the positioning strip; the side of the moving block is a slider, which slides in cooperation with the guide rail.

5. The pipette according to any one of claims 1 to 4, characterized in that, The plunger includes a main rod and a connector, and the main rod is made of ceramic material; A first groove is provided on the outer wall of the rear end of the main rod, and an insertion hole is provided in the middle of the connector. A second groove is provided on the inner wall of the insertion hole of the connector. The first groove and the second groove correspond to each other, and a positioning rubber ring is provided between the first groove and the second groove. The connector is fixed to the rear end of the main rod by the positioning rubber ring.

6. The pipette according to any one of claims 1 to 4, characterized in that, The plug rods have the same diameter at least in the middle section region; The rear end of the first sleeve is provided with a sealing seat, the inner wall of the sealing seat is provided with a receiving groove, and a sealing ring is provided in the receiving groove; A tail cavity is formed between the front end region of the sealing ring on the sealing seat and the plug rod, and a vent pipe is provided on the sealing seat, which communicates with the tail cavity.

7. The pipette according to any one of claims 1 to 4, characterized in that, A first protrusion and a second protrusion are provided at the front end of the first sleeve, and a third protrusion is provided at the front end of the second sleeve. The first protrusion and the second protrusion are spaced apart along the axial direction of the first sleeve, and the first protrusion and the second protrusion protrude outward in the circumferential direction relative to the outer wall of the main body of the first sleeve at that location, and the third protrusion protrudes inward in the circumferential direction relative to the inner wall of the main body of the second sleeve at that location.

8. A pipetting method based on the pipette of claim 1, characterized in that, The method includes the following steps: The front end of the first sleeve is aligned with the rear end of the gun head, and the rear end of the gun head is fitted into the front end of the first sleeve. The rear end of the nozzle is engaged with the front end of the first sleeve; The pipette tip is guided to the position where the liquid is to be transferred through the first tubing; The drive mechanism drives the plunger rod to move along its axial direction to its rear end to draw liquid through its transmission part, and drives the plunger rod to move along its axial direction to its front end to discharge liquid, thus completing the liquid transfer operation. The drive mechanism continues to move forward, pushing the second sleeve towards its front end. The front end of the second sleeve abuts against the rear end of the gun head, causing the gun head to gradually detach from the first sleeve, thus completing the removal of the gun head.

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