Electric pipettor
By combining the rigid coupling of the synchronous pulley set and the lead screw with the sensor assembly, the problem of insufficient accuracy of electric pipettes is solved, realizing high-precision and high-repeatability pipetting operations, and meeting the needs of automated experiments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- BAIQUAN JUXING (BEIJING) TECH CO LTD
- Filing Date
- 2025-05-12
- Publication Date
- 2026-04-14
AI Technical Summary
Existing electric pipettes suffer from insufficient accuracy. Direct-drive motors or gear transmissions are prone to piston displacement deviation due to mechanical clearance and wear. After long-term use, the backlash increases, causing return error. Furthermore, they lack digital feedback.
The system employs a rigid coupling between a synchronous pulley set and a lead screw, and eliminates the risk of gear backlash and wear through synchronous belt drive. Combined with a sensor assembly, it directly monitors the piston position for feedback, thereby improving accuracy and repeatability.
It achieves high-precision and highly repeatable pipetting operations, eliminates mechanical errors, enhances the digital control capabilities of the pipette, and adapts to automated experimental processes.
Smart Images
Figure CN224114000U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of pipette technology, specifically to an electric pipette. Background Technology
[0002] As a core laboratory tool, the accuracy and reliability of pipettes directly affect experimental results. Currently, mainstream pipetting techniques can be divided into traditional manual pipettes and electric pipettes. Manual pipettes rely on the operator manually pressing the piston, with liquid volume controlled by spring return and mechanical limit. Accuracy is significantly affected by the operator's force and speed, and prolonged operation can easily lead to fatigue, resulting in liquid residue or volume deviation. They also lack digital feedback and cannot be adapted to automated experimental workflows. Most existing electric pipettes use motors to drive the piston movement, partially solving the uncertainty of manual operation, but still suffer from insufficient accuracy: direct-drive motors or gear transmissions are prone to piston displacement deviation due to mechanical backlash and wear, and long-term use can lead to increased backlash and hysteresis errors. Utility Model Content
[0003] The technical problem to be solved by this utility model is to overcome the existing defects and provide an electric pipette. Through the rigid coupling of the synchronous wheel set and the lead screw, the lead screw transmission has high precision, which greatly improves the accuracy and repeatability of pipetting operations and can effectively solve the problems in the background art.
[0004] To achieve the above objectives, this utility model provides the following technical solution: an electric pipette, comprising a housing and a pipette body disposed on one side of the lower surface of the housing, a motor disposed on the other side of the lower surface of the housing, the output shaft of the motor passing through the interior of the housing and connected to a small synchronous pulley, a small synchronous pulley and a large synchronous pulley being rotatably disposed inside the housing, a synchronous belt being disposed between the small synchronous pulley and the large synchronous pulley, a lead screw coaxially mounted on the lower side of the large synchronous pulley, a lead screw nut being threadedly connected to the outer side of the lead screw, the lead screw nut being slidably disposed inside the pipette body, a piston rod being fixedly mounted on the lead screw nut, a pipette head mounting component being disposed on the lower surface of the pipette body, and the piston rod being slidably disposed within the pipette head mounting component.
[0005] As a preferred technical solution of this utility model, a sensor assembly for detecting the position of the piston is provided inside the gun body.
[0006] As a preferred embodiment of this utility model, the sensor assembly includes a counter disposed on the upper side of the gun body, and a counting block corresponding to the counter is fixedly disposed on the large synchronous wheel.
[0007] As a preferred embodiment of this invention, the sensor assembly includes a range sensor disposed on the upper side of the gun body, with the detection end of the range sensor facing the upper surface of the lead screw nut.
[0008] As a preferred embodiment of this utility model, the inner surface of the gun body is provided with a plurality of grooves, and the sensor assembly includes a proximity switch installed in the groove for detecting the position of the lead screw nut.
[0009] As a preferred technical solution of this utility model, a sensing plate is provided on the side of the lower surface of the lead screw nut away from the piston rod, and a sensor corresponding to the sensing plate is provided on the lower side of the gun body.
[0010] As a preferred technical solution of this utility model, an annular ejector head is provided on the lower inner side of the gun body. The ejector head has a T-shaped cross-section, and the bottom end of the ejector head extends out of the gun body and is slidably disposed on the outside of the gun head mounting piece. A spring is provided inside the gun body, and the spring is disposed on the lower side of the ejector head and sleeved on the outside of the piston rod.
[0011] As a preferred technical solution of this utility model, a rotating shaft is fixedly installed on the lower surface of the center of the large synchronous pulley, a bearing is installed inside the cover, the bearing is installed on the outside of the rotating shaft, and the rotating shaft is connected to the lead screw through a coupling.
[0012] As a preferred embodiment of this utility model, an O-ring is fixedly provided on the lower inner side of the gun body, and the O-ring is sleeved on the outer side of the piston rod.
[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: by rigidly coupling the synchronous pulley set and the lead screw, the rotation of the motor is converted into the linear motion of the piston rod for liquid aspiration and dispensing operations, eliminating the risks of gear backlash and wear, and the lead screw transmission has high precision, which greatly improves the accuracy and repeatability of pipetting operations; at the same time, by setting a sensor assembly to detect the piston position, the absolute position of the piston rod can be directly monitored and fed back, which can further improve the accuracy of the pipette. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of this utility model;
[0015] Figure 2 This is a schematic diagram of the internal structure of this utility model.
[0016] In the diagram: 1. Cover, 2. Gun body, 3. Gun head, 4. Motor, 5. Sensor, 6. Small synchronous pulley, 7. Synchronous belt, 8. Bearing, 9. Sensor plate, 10. Gun head retraction component, 11. Gun head mounting component, 12. Large synchronous pulley, 13. Coupling, 14. Lead screw, 15. Piston rod, 16. O-ring, 17. Spring, 18. Counter, 19. Counting block, 20. Distance sensor, 21. Proximity switch. Detailed Implementation
[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0018] Please see Figure 1-2 This utility model provides a technical solution: an electric pipette, including a cover 1 and a gun body 2 disposed on one side of the lower surface of the cover 1. The cover 1 is a metal or high-strength plastic shell, which isolates external dust and liquid splashes and protects the internal precision transmission system.
[0019] The lower surface of the gun body 2 is provided with a gun head mounting part 11, and the gun head 3 is mounted on the gun head mounting part 11.
[0020] A motor 4 is installed on the other side of the lower surface of the cover 1. The output shaft of the motor 4 passes through the interior of the cover 1 and is connected to a small synchronous pulley 6. A small synchronous pulley 6 and a large synchronous pulley 12 are rotatably mounted inside the cover 1. A synchronous belt 7 is installed between the small synchronous pulley 6 and the large synchronous pulley 12. The motor 4 can drive the large synchronous pulley 12 to rotate via the small synchronous pulley 6 and the synchronous belt 7. The rubber material of the synchronous belt 7 reduces vibration and noise, and reduces wear by more than 50% compared to gear transmission. Simultaneously, the synchronous belt 7 can eliminate backlash errors in gear transmission.
[0021] A lead screw 14, coaxial with the large synchronous pulley 12, is mounted on its lower side. A lead screw nut is threaded onto the outer side of the lead screw 14 and slides up and down inside the gun body 2. A piston rod 15 is fixedly mounted on the lower surface of the lead screw nut and slides within the gun head mounting part 11. When the large synchronous pulley 12 rotates, it drives the lead screw 14 to rotate. The lead screw 14, through the lead screw nut, drives the piston rod 15 to rise and fall, performing liquid suction and discharge operations. Through the rigid coupling between the synchronous pulley assembly and the lead screw, the rotation of the motor is converted into the linear motion of the piston rod 15 for liquid suction and discharge operations, eliminating the risks of gear backlash and wear. Moreover, the lead screw transmission has high precision, greatly improving the accuracy and repeatability of the pipetting operation.
[0022] An O-ring 16 is fixedly installed on the lower inner side of the gun body 2. The O-ring 16 is fitted onto the outside of the piston rod 15, forming a sealed cavity with the gun head mounting part 11 and the gun head 3, improving sealing performance and maintaining a leak-free state for a longer period after liquid absorption. The O-ring 16 is made of fluororubber. Corrosion-resistant O-rings 16 (such as FFKM) maintain elasticity in acid / alkali environments, with a liquid leakage rate ≤0.1μL within 4 hours. Additionally, a PTFE coating can be applied to the surface of the O-ring 16 to reduce the movement resistance of the piston rod 15 and extend the life of the sealing ring.
[0023] The pipette body 2 is equipped with a sensor assembly for detecting the piston position. It directly monitors the absolute position of the piston rod and provides feedback, which can further improve the accuracy of the pipette.
[0024] In Example 1, the sensor assembly includes a counter 18 mounted on the upper side of the gun body 2. A counting block 19 corresponding to the counter 18 is fixedly mounted on the large synchronous wheel 12. The counter 18 can be a photoelectric or Hall sensor, and the counting block 19 can be a reflector or metal. Each rotation of the large synchronous wheel 12 triggers the counter 18 once by the counting block 19, and the displacement of the piston rod 15 is calculated by accumulating the number of pulses. This method is low-cost and suitable for general accuracy scenarios (error ≤ 0.5%), achieving low-cost displacement monitoring through pulse counting. It also exhibits strong anti-interference capabilities; the photoelectric / Hall signal is unaffected by oil or magnetic fields, making it suitable for complex laboratory environments.
[0025] In Example 2, the sensor assembly includes a ranging sensor 20 disposed on the upper inner side of the gun body 2. The ranging sensor 20 is preferably a laser ranging sensor, with its detection end facing the upper surface of the lead screw nut, directly detecting displacement changes on the upper surface of the lead screw nut. Laser ranging offers high accuracy and is suitable for ultra-micro volume pipetting needs such as single-cell manipulation. Sensor data is directly fed back to the motor controller, allowing for dynamic compensation of mechanical errors (such as belt tension and temperature deformation).
[0026] In embodiment three, the inner surface of the gun body 2 is provided with several grooves. The sensor assembly includes a magnetic or capacitive proximity switch 21 installed in the groove for detecting the position of the lead screw nut. Detecting the position of the lead screw nut, i.e., the position of the piston rod 15, allows for the preset liquid suction / discharge endpoint position, avoiding overshoot risk and improving operational safety. Furthermore, the number of proximity switches can be increased or decreased as needed to flexibly adapt to different liquid transfer ranges.
[0027] The housing 1 contains a controller for controlling the motor 4 and the sensor assembly. This controller is preferably a commonly used microcontroller or PLC controller, such as an Arduino series microcontroller or a Siemens S7 series PLC controller.
[0028] In a preferred embodiment, a sensing element 9 is provided on the lower surface of the lead screw nut, away from the piston rod 15. A sensor 5 corresponding to the sensing element 9 is provided on the lower side of the gun body 2, and the sensor 5 is connected to the controller. The sensor 5 can be photoelectric or electromagnetic, such as a photoelectric sensor or a Hall sensor. When the sensing element 9 moves down with the piston rod 15 to the position of the sensor 5, it triggers a home calibration signal. The initial position of the piston rod 15 is automatically calibrated each time the system starts, eliminating accumulated errors. If the sensing element 9 fails to trigger a signal within a specified time, the system can determine that the transmission is abnormal and issue an alarm.
[0029] The controller, motor 4, sensor assembly, and sensor 5 are all powered by the pipette's built-in battery. The battery can be a commonly used type of battery in existing technology, such as a lithium-ion battery.
[0030] The controller, motor 4, sensor assembly and sensor 5 used in this application are all commonly used electronic components in the prior art. Their specific structure, working principle, control method and circuit connection are all well known technologies and will not be described in detail here.
[0031] In a preferred embodiment, a ring-shaped ejector head 10 is provided on the lower inner side of the gun body 2. The ejector head 10 has a T-shaped cross-section, and its bottom end protrudes from the outside of the gun body 2 and is slidably positioned on the outside of the gun head mounting component 11. A spring 17 is provided inside the gun body 2, positioned below the ejector head 10 and sleeved on the outside of the piston rod 15. When the piston rod 15 descends to its end, it pushes the ejector head 10 downward to eject the gun head; when it ascends, the spring 17 resets the ejector head 10. This design eliminates the need for an additional motor or button, automatically ejecting the gun using piston movement, simplifying the operation process.
[0032] In a preferred embodiment, a rotating shaft is fixedly installed on the lower surface of the center of the large synchronous pulley 12, a bearing 8 is installed inside the cover 1, the bearing 8 is installed on the outside of the rotating shaft, the rotating shaft is connected to the lead screw 14 through the coupling 13, and the bearing 8 is pre-coated with long-life grease, so no regular maintenance is required.
[0033] Action flow:
[0034] Install the electric pipette and pipette tip 3, prepare the container solution, and after powering on, it will automatically return to the origin (without the pipette tip immersed in the liquid surface). When the sensor plate 9 moves down to the point where the sensor 5 lights up, it will stop.
[0035] When a suction command is received (the nozzle is immersed in the liquid), the motor rotates forward, and the piston rod moves upward to the set distance and then stops (moving to the discharge position).
[0036] When a drain command is received, the motor rotates forward, and the piston rod moves downward to a set distance and then stops, draining the liquid from the nozzle.
[0037] When the electric pipette stops midway after aspiration, without any discharge, it can remain leak-free for more than 4 hours.
[0038] After the pipette tip has finished draining, (the ultra-high precision electric pipette moves to the pipette tip storage position) the piston rod continues to move downwards, retracting the pipette tip.
[0039] The parts not disclosed in this utility model are all prior art, and their specific structures, materials, and working principles will not be described in detail. Although embodiments of this utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this utility model, the scope of which is defined by the appended claims and their equivalents.
Claims
1. An electric pipette, comprising a housing (1) and a pipette body (2) disposed on one side of the lower surface of the housing (1), characterized in that: A motor (4) is provided on the other side of the lower surface of the cover (1). The output shaft of the motor (4) passes through the inside of the cover (1) and is connected to the small synchronous pulley (6). The small synchronous pulley (6) and the large synchronous pulley (12) are rotatably arranged inside the cover (1). A synchronous belt (7) is provided between the small synchronous pulley (6) and the large synchronous pulley (12). A lead screw (14) coaxial with the large synchronous pulley (12) is installed on the lower side of the large synchronous pulley (12). A lead screw nut is threaded on the outside of the lead screw (14). The lead screw nut is slidably arranged inside the gun body (2). A piston rod (15) is fixedly installed on the lead screw nut. A gun head mounting part (11) is provided on the lower surface of the gun body (2). The piston rod (15) is slidably arranged inside the gun head mounting part (11).
2. The electric pipette according to claim 1, characterized in that: The gun body (2) is equipped with a sensor assembly for detecting the position of the piston.
3. The electric pipette according to claim 2, characterized in that: The sensor assembly includes a counter (18) disposed on the upper side of the gun body (2), and a counting block (19) corresponding to the counter (18) is fixedly disposed on the large synchronous wheel (12).
4. The electric pipette according to claim 2, characterized in that: The sensor assembly includes a range sensor (20) disposed on the upper inner side of the gun body (2), with the detection end of the range sensor (20) facing the upper surface of the lead screw nut.
5. An electric pipette according to claim 2, characterized in that: The inner surface of the gun body (2) is provided with several grooves, and the sensor assembly includes a proximity switch (21) installed in the groove for detecting the position of the lead screw nut.
6. The electric pipette according to claim 1, characterized in that: A sensor plate (9) is provided on the lower surface of the lead screw nut away from the piston rod (15), and a sensor (5) corresponding to the sensor plate (9) is provided on the lower side of the gun body (2).
7. An electric pipette according to claim 1, characterized in that: The gun body (2) has an annular ejector head (10) on its lower inner side. The ejector head (10) has a T-shaped cross-section and its bottom end protrudes from the gun body (2) and is slidably disposed on the outside of the gun head mounting part (11). A spring (17) is disposed inside the gun body (2). The spring (17) is disposed on the lower side of the ejector head (10) and sleeved on the outside of the piston rod (15).
8. An electric pipette according to claim 1, characterized in that: A rotating shaft is fixedly installed on the lower surface of the center of the large synchronous pulley (12). A bearing (8) is installed inside the cover (1). The bearing (8) is installed on the outside of the rotating shaft. The rotating shaft is connected to the lead screw (14) through a coupling (13).
9. An electric pipette according to any one of claims 1-8, characterized in that: An O-ring (16) is fixedly installed on the lower inner side of the gun body (2), and the O-ring (16) is sleeved on the outside of the piston rod (15).