A modular pipette driven by a DC brushless servo system and its control method

Abstract

This invention discloses a modular pipette driven by a DC brushless servo system and its control method, relating to the field of pipette technology. The modular pipette driven by a DC brushless servo system and its control method provided by this invention use a DC brushless servo system to drive the pipette. The drive control system can feed back the speed parameters of the DC brushless motor according to different scenario requirements, enabling it to drive the DC brushless motor to operate at a first preset speed, so that the modular pipette can complete the aspiration / discharge action; or the drive control system can drive the DC brushless motor to operate at a second preset speed, so as to drive the pipetting consumable unloading unit, so that the modular pipette can complete the pipetting consumable unloading action.

Description

Technical Field

[0001] This invention relates to the field of pipette technology, and more specifically to a modular pipette driven by a DC brushless servo system and its control method. Background Technology

[0002] In biochemical testing and / or experiments, the transfer of small amounts of liquid between different containers is involved. While manual methods can be used to transfer small amounts of sample solution or other liquids, the accuracy of this transfer heavily relies on the operator's experience. Furthermore, manual operation can pose safety risks to operators in scenarios with contamination risks. With technological advancements, more automated equipment has entered this field. Compared to other methods, automated equipment offers advantages such as high consistency in liquid transfer volume, good continuity, and controllable quality. Automated modular pipettes have been designed to meet the needs of automated liquid transfer scenarios within equipment. These types of pipettes typically also feature small size and the ability to be installed in multiple sets in parallel.

[0003] Research on pipette solutions for precise volume control began as early as the 1970s and 80s. US patent application US4369665A designed a handheld pipette device and a corresponding control circuit for precise control of small volume pipetting. It also incorporated two limit stop devices to restrict the piston rod's range of motion. It's important to note that this application explicitly specifies the pipette's drive motor as a stepper motor. US patent application US4586546A, filed in October 1984, disclosed a pipette with a drive motion system. This design places the pipette within a coordinate axis system capable of lateral and longitudinal movement. Driven by a stepper motor, it achieves different positions and aspiration / transfer effects. It's important to note that this disclosed pipette is not a modular pipette, making it unsuitable for the high integration requirements of modern automated equipment that demand modular designs for different functional modules. Furthermore, this type of pipetting results in variations in volume between different sample wells, leading to higher maintenance costs. US Patent Application US5507193A designed a non-handheld modular pipette, providing insights for the design of modular pipettes in subsequent automated equipment. US Patent US7314598B2 was the earliest and most comprehensive protector of a modular pipette design, disclosing a scheme for parallel liquid transfer using multiple sets of this type of pipette. In this scheme, the drive motor for the modular pipette is a stepper motor. When the drive pulse signal is activated, it can use disposable consumables connected to the pipette to aspirate or expel liquid. Each pipette module is equipped with a pressure sensor, which is optimally connected to the pipette's piston cylinder to achieve pipette level detection and control of the insertion depth of the pipette consumables. Based on this, Godconn designed a stepper motor-driven modular pipetting device, Cavro ADP. A large gear reduction transmission mechanism connects the stepper drive motor and the pipette plunger, achieving a drive accuracy of 25 nL / step. This type of pipette is commonly found in various medical devices. Domestic manufacturers have also adopted stepper motors in their designs to compete with these pipettes. These include the ADP1000 designed by Shenzhen Daken, which uses a stepper motor to drive a lead screw and nut to drive the plunger, and integrates an encoder to achieve closed-loop control, enabling more accurate position control. Many patent documents also explicitly state that their drive motors are stepper motors. Chinese utility model patent CN204314318U discloses a scheme for using a stepper motor to drive a pulley for pipetting, and CN212255375U also discloses a scheme for using a stepper motor to drive the pipette's lead screw, etc.

[0004] Because stepper motors were researched early in modular pipettes, most manufacturers have adopted them as the drive source in their pipette designs. However, the original design intent of stepper motors was to control the motor rotor using a predetermined step angle. While this design ensures accuracy, its operating speed is severely limited. Stepper motors have a minimum number of steps required, and to achieve the set speed, a reduction gear is typically configured to increase the drive torque. Stepper motor drive force usually has redundant design, making it unsuitable for sudden load changes, such as blockages, which can reduce the reliability of stepper motor operation. Furthermore, stepper motors suffer from high power consumption and generate significant waste heat. Currently, pipettes designed for compactness typically use only one drive motor. However, pipettes operate under complex conditions, with varying motor requirements across different steps. The stepper motors currently used are ill-suited to these diverse scenarios. For example, pipettes need to perform rapid aspiration / dissipation actions as well as high-torque unloading of pipetting consumables. To reliably unload consumables, high-ratio reduction gears are necessary to achieve greater torque. For instance, Tiken's pipette design features a large-diameter gear transmission mechanism, complicating the system design. On the other hand, using ordinary stepper motors struggles to guarantee speed during aspiration / dissipation. Some domestic manufacturers have addressed this by simplifying the connection between the pipette and consumables, but overly loose connections result in poor sealing, compromising pipetting accuracy and posing a risk of dripping due to external forces during transfer. Therefore, research into pipette drive sources is essential to better adapt modular pipettes to demanding conditions such as long-term, precise pipetting operations. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by providing a modular pipette driven by a brushless DC servo system and its control method. The invention employs a brushless DC servo system to drive the pipette, and the drive control system can provide feedback on the rotational speed parameters of the brushless DC motor according to different scenario requirements, enabling it to drive the brushless DC motor to operate at a first preset speed, thus allowing the modular pipette to complete aspiration / discharge actions; or the drive control system can drive the brushless DC motor to operate at a second preset speed, thereby driving the pipetting consumable unloading unit to allow the modular pipette to complete the pipetting consumable unloading action.

[0006] The technical solution adopted in this invention is as follows:

[0007] A modular pipette driven by a DC brushless servo system includes a drive control system, a pipetting module, a consumable loading / unloading module, and a transmission module. The drive control system can act on the pipetting module and the consumable unloading module respectively through the transmission module. The drive control system includes a drive module and a control module. The control module is signal-connected to the drive module, and the drive module is electrically connected to a DC brushless motor. The drive module can drive the DC brushless motor to act on the pipetting module at a first preset speed to enable the pipetting module to perform aspiration / discharge actions. The drive module can also drive the DC brushless motor to act on the consumable unloading module at a second preset speed to enable the consumable unloading module to perform pipetting consumable unloading actions.

[0008] Furthermore, the first preset rotational speed is 8-500 times the second preset rotational speed.

[0009] Furthermore, the first preset speed is 85%-100% of the maximum allowable operating speed of the brushless DC motor.

[0010] Furthermore, when the first preset speed is running, the input power of the brushless DC motor fluctuates, and the torque output of the brushless DC motor changes by no more than 40%.

[0011] Furthermore, the drive control system also includes a sensing module, which is signal-connected to the control module. The sensing module and the control module transmit collected data values, and the control module can transmit control signals to the drive module based on the collected data values ​​transmitted by the sensing module.

[0012] Furthermore, the sensing module includes a current detection unit, which can collect current data values ​​of at least two phase windings in the brushless DC motor. The current detection unit is signal-connected to the control module, and the control module can transmit control signals to the drive module based on the current data values ​​transmitted by the current detection unit.

[0013] Furthermore, the sensing module includes an encoding sensing unit, which can collect position information data of the permanent magnet rotor in the brushless DC motor. The encoding sensing unit is signal-connected to the control module, and the control module can transmit control signals to the drive module based on the position information data transmitted by the encoding sensing unit.

[0014] A modular pipette control method driven by a DC brushless servo system includes the following steps:

[0015] Pipetting steps: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate at a first preset speed. The lead screw rotates together with the motor shaft of the brushless DC motor through a coupling. The sliding component on the lead screw drives the plunger to move relative to the pipetting consumable connection part. When the plunger moves towards the pipetting consumable connection part, the volume of the pipetting cavity formed between the plunger and the pipetting consumable connection part decreases, and the dispensing action is performed. When the plunger moves away from the pipetting consumable connection part, the volume of the pipetting cavity formed between the plunger and the pipetting consumable connection part increases, and the aspiration action is performed.

[0016] Unloading steps: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate forward at a second preset speed. The lead screw rotates together with the motor shaft of the brushless DC motor through a coupling. The sliding component on the lead screw moves toward the unloading abutment. After the sliding component abuts against the unloading abutment, it acts on the unloading abutment, causing the unloading abutment to move toward the direction of the pipetting consumable. At the same time, the unloading abutment drives the unloading sleeve to move relative to the pipetting consumable connection part, and causes the unloading sleeve to abut against the pipetting consumable. It continues to move until the unloading sleeve is flush with or almost flush with the lower part of the sealing connection end of the pipetting consumable connection part. The pipetting consumable that is abutted falls off from the sealing connection end of the pipetting consumable connection part, completing the unloading of the pipetting consumable.

[0017] Reset Procedure: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate in the opposite direction. The lead screw rotates with the brushless DC motor through the coupling. The slider assembly moves away from the unloading abutment until it no longer acts on the unloading abutment. The unloading abutment is reset by the reset element, which drives the unloading sleeve to reset, exposing the sealing connection end. The sealing connection end can now be used to connect to a new pipetting consumable.

[0018] Furthermore, the first preset speed is 8-500 times the second preset speed, and / or the first preset speed is 85%-100% of the maximum allowable operating speed of the brushless DC motor, and / or when the first preset speed is running, the input power of the brushless DC motor fluctuates, and the torque output of the brushless DC motor does not change by more than 40%.

[0019] Furthermore, the sensing module is signal-connected to the control module. The control module can adjust the speed of the brushless DC motor based on the data transmitted by the sensing module and send a control signal to the drive module, so that the drive module drives the brushless DC motor to rotate at a predetermined speed. The sensing module includes a current detection unit and / or an encoding sensing unit. The current detection unit can collect the current data values ​​of at least two phase windings in the brushless DC motor, and the encoding sensing unit can collect the position information data of the permanent magnet rotor in the brushless DC motor.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] 1. This invention employs a DC brushless servo system to drive the pipette. The drive control system can feed back the rotational speed parameters of the DC brushless motor according to different scenario requirements, enabling it to drive the DC brushless motor to operate at a first preset speed so that the modular pipette can complete the aspiration / discharge action; or the drive control system can drive the DC brushless motor to operate at a second preset speed so that the pipetting consumable unloading unit can drive the modular pipette to complete the pipetting consumable unloading action. Optimally, the first preset speed is 8-500 times the second preset speed, and the first preset speed is 85%-100% of the maximum allowable operating speed of the DC brushless motor. This can adapt to different scenario operating requirements and accommodate different needs for high-speed and high-torque operation.

[0022] 2. The pipette used in this invention has a drive control system that can drive the pipette drive motor to run at a first preset speed with fluctuating input power, and ensure that the output torque changes by no more than 40%. This allows for stable control of the pipette's operation. Through negative feedback closed-loop control of the current detection unit and the encoding sensing unit, precise control of the motor's operation is achieved, which can significantly reduce the waste heat generated when the pipette is used in medical equipment. Furthermore, the independent setting of the current detection unit can meet the requirements of easy maintenance, such as simple problem localization, and there is no need to worry about the interference problems that may exist with integrated settings.

[0023] 3. The drive control system used in this invention can know the current execution state of the pipette and, based on this state, make the modular pipette operate in one of the following modes:

[0024] The drive control system can drive the brushless DC motor to run at a first preset speed so that the modular pipette can complete the aspiration / discharge action; the drive control system can also drive the brushless DC motor to run at a second preset speed so that the pipetting consumable unloading unit can drive the modular pipette to complete the pipetting consumable unloading action, and also reliably ensure the pipette's differentiated operation requirements for different scenarios, and the implementation method is simple and reliable. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the DC brushless servo system and the modular pipette it drives, provided by the present invention.

[0026] Figure 2 This is a schematic diagram of the internal structure of the pipette of the present invention;

[0027] Figure 3 This is a schematic block diagram of the DC brushless servo system driver of the present invention;

[0028] Figure 4 This is a schematic diagram of the DC brushless motor control and drive circuit of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating the rotation principle of the permanent magnet rotor of the brushless DC motor of the present invention.

[0030] Figure 6 This is a schematic diagram of a DC brushless servo system circuit according to the present invention;

[0031] Figure 7 This is a schematic diagram of another DC brushless servo system circuit according to the present invention;

[0032] Figure 8 This is a schematic diagram of the operating range of the brushless DC motor of the present invention;

[0033] Figure 9 This is a schematic diagram of the structure of the correction element of the present invention.

[0034] In the diagram, the markings are as follows: 10-Housing, 100-Pipette consumables, 101-DC brushless motor, 102-Coupling, 103-Pipette consumable connection, 104-Pipette consumable unloading part, 105-Lead screw, 106-Slider assembly, 107-Plug rod, 20-Drive control system, 201-Sensing module, 202-Control module, 203-Drive module, 2022-Current detection unit, 2023-Encoding sensing unit, 401-Sealed connection end, 331-Clamping component, 332-Correction element, 333-Plug rod cap, 502-Unloading connection. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] Example 1

[0038] A modular pipette driven by a DC brushless servo system, such as Figure 2 , Figure 9As shown, the system includes a drive control system 20, a pipetting module, a consumable loading / unloading module, and a transmission module. The drive control system 20 can act on the pipetting module and the consumable unloading module respectively through the transmission module. The drive control system 20 includes a drive module 203 and a control module 202. The control module 202 is signal-connected to the drive module 203, and the drive module 203 is electrically connected to the DC brushless motor 101. The drive module 203 can drive the DC brushless motor 101 to act on the pipetting module at a first preset speed, so that the pipetting module can complete the aspiration / discharge action. The drive module 203 can also drive the DC brushless motor 101 to act on the consumable unloading module at a second preset speed, so that the consumable unloading module can complete the unloading action of the pipetting consumable 100. The pipetting module includes a stopper rod 107, a pipetting consumable 100 connecting portion, and a pipetting consumable 100. One end of the pipetting consumable 100 connecting portion is matched with the stopper rod 107, and the other end is detachably connected to the pipetting consumable 100. At least one end of the stopper rod 107 is inserted into the interior of the pipetting consumable 100 connecting portion. The consumable loading and unloading module includes an unloading abutment and an unloading sleeve. The unloading sleeve is wrapped around the outer wall of the pipetting consumable 100 connecting portion. The unloading abutment can... The transmission module drives the unloading sleeve to move relative to the connection part of the pipetting consumable 100. The transmission module includes a lead screw 105 and a sliding assembly. The lead screw 105 is connected to the DC brushless motor 101 through a coupling 102. The lead screw 105 is provided with a slider assembly 106. The plug rod 107 is connected to the slider assembly 106. The slider assembly 106 can abut against the unloading abutment and, driven by the DC brushless motor 101, drives the unloading abutment to slide relative to the housing 10.

[0039] The drive control system 20 further includes a sensing module 201, which is signal-connected to the control module 202. The sensing module 201 and the control module 202 transmit collected data values. The control module 202 can transmit control signals to the drive module 203 based on the collected data values ​​transmitted by the sensing module 201.

[0040] The sensing module 201 includes a current detection unit 2022, which can collect the current data values ​​of at least two phase windings in the brushless DC motor 101. The current detection unit 2022 is connected to the control module 202, and the control module 202 can transmit control signals to the drive module 203 based on the current data values ​​transmitted by the current detection unit 2022.

[0041] The sensing module 201 includes an encoding sensing unit 2023, which can collect position information data of the permanent magnet rotor in the brushless DC motor 101. The encoding sensing unit 2023 is connected to the control module 202, and the control module 202 can transmit control signals to the drive module 203 based on the position information data transmitted by the encoding sensing unit 2023.

[0042] One end of the lead screw 105 is connected to the body via a connecting bearing to form a bearing end, and the other end is connected to the DC brushless motor 101 via a coupling 102 to form a cantilever end. The cantilever end of the lead screw 105 connected to the coupling 102 passes through a mounting hole on the housing 10 and matches the coupling 102, forming an annular gap between the lead screw 105 and the mounting hole. More preferably, this annular gap has a minimum clearance size range of 0.5-2.5 mm, thus ensuring that even with a certain axial load, friction between the lead screw 105 and the housing 10 is not possible, making the operation of the lead screw 105 more reliable. This design also avoids problems such as excessive internal stress caused by constraints at both ends of the lead screw 105. One end of the lead screw 105 is connected to the housing 10 via a connecting bearing. There are two connecting bearings, but more can be used. Multiple connecting bearings are used to ensure higher reliability in axial load sharing. If only one connecting bearing is set at the bearing end, the axial load will be borne solely by this connecting bearing when the pipetting consumable 100 is unloaded, which may easily lead to safety and reliability problems such as the connecting bearing being pulled apart or the inner ring being pulled out.

[0043] The stopper rod 107 and the slider assembly 106 are adjustablely connected via a correction element 332 with elastic properties. Specifically, the stopper rod 107 can be made of ceramic, plastic, or other materials, with non-metallic materials being the most preferred. A stopper rod cap 333 is provided at the end of the stopper rod 107; this cap may be made of a different material than the stopper rod 107, such as copper or aluminum. One end of the stopper rod 107 is adjustablely connected to the drive device via the correction element 332 with elastic properties, while the other end is at least partially inserted into the interior of the pipetting consumable connection portion 103. Under the action of the drive device, the stopper rod 107 can reciprocate linearly along the axial direction of the pipetting consumable connection portion 103. When the stopper rod 107 moves relative to the pipetting consumable, it can create a suction effect. A clamping member 331 is provided at the correction element 332 to provide pre-tightening force to the correction element 332. The elastic properties of the correction element 332 can meet the needs of scenarios requiring adjustment, and the clamping element 331 provides clamping force to ensure that the plug rod 107 is tightly connected to the plug rod connector without wobbling. Due to possible deviations caused by machining or assembly errors of components, or deviations due to internal stress, the plug rod axis L2 and the slide rail axis L1 may not be parallel, resulting in a possible skew in different directions. In existing designs, because this deviation is relatively small, some designers choose motors with larger torque or transmission structures with larger transmission ratios to overcome the difference in driving force caused by this type of deviation. However, this design has many problems in scenarios requiring high pipetting accuracy. In this embodiment, a correction element 332 is introduced into the connection between the slider assembly 106 and the plug rod 107. This element is a spring element with a predetermined clamping force and stiffness coefficient, and it has elastic deformation capability, thus ensuring that the connection position has... The possibility of self-adjustment exists because as the slider assembly 106 moves downward, the non-parallelism deviation will generate different forces at different positions at the connection between the slider assembly 106 and the stopper rod 107. These different forces will be converted into differences in the deformation of the spring at different positions. Therefore, as the slider assembly 106 moves downward, the non-parallelism is compensated by the different deformations of the spring. Thus, the pipette has the function of self-correcting the non-parallelism of the stopper rod 107 during reagent operation. This will improve the problem of increased friction caused by non-parallelism. Of course, in actual use, there are many reasons for non-parallelism, not limited to the types mentioned above. Non-parallelism itself may also be generated dynamically, or due to usage time or number of disassemblies.

[0044] The coupling 102 and the brushless DC motor 101 are located outside the housing 10, and the drive motor is constrained to the housing 10 by a mounting block. The brushless DC motor 101 includes a motor shaft protruding from the motor body. The brushless DC motor 101 is connected to the mounting block 13 by a motor connecting screw, and the motor shaft passes through the mounting block 13 and is inserted into the shaft coupling hole of the coupling 102. The coupling 102 includes a first coupling portion for connecting the brushless DC motor 101 and a second coupling portion for connecting the lead screw 105. The first coupling portion can be connected to the brushless DC motor 101 through its shaft coupling hole, and the second coupling portion can be connected to the drive mechanism through its shaft coupling hole. The coupling 102 is provided with a bore diameter adjustment unit. The bore diameter adjustment unit includes an adjustment hole and an adjustment screw. The adjustment hole extends radially from the outer wall of the coupling 102 to the shaft coupling hole, and the adjustment screw is threadedly connected to the adjustment hole. The DC brushless motor 101 or lead screw 105 can be restricted or released by controlling the insertion depth of the adjusting screw along the adjusting hole. The mounting block 13 also includes a through-hole for detachable connection between the mounting block 13 and the housing 10 via a connecting screw. Specifically, both the coupling 102 and the DC brushless motor 101 are located outside the housing 10, and the mounting notch also reduces the longitudinal dimension of the pipette, ensuring a compact design.

[0045] Example 2

[0046] A modular pipette driven by a DC brushless servo system, such as Figure 1The diagram shows the DC brushless servo system and its driven modular pipette provided by this invention. Because each pipette has an independent drive motor, the modular pipette is more suitable for precise multi-sample transfer operations. While multi-row pipettes driven by a single drive motor may have variations in pipetting volume, modular pipettes can achieve sequential aspiration and dispensing by being connected in parallel, reducing the risk of contamination between adjacent liquids during operation. Therefore, designing a modular pipette is essential. The modular pipette of this invention has a basically flat housing 10, with its thickness much smaller than its width and / or length, and a basic cubic shape, such as a cuboid. A DC brushless motor 101 is disposed at one end of the housing 10, which is connected to the internal structure of the housing 10 via a coupling 102. The DC brushless motor 101 is fixedly connected to the housing 10 via a mounting block 13. Optimally, a notch is provided on the housing 10, and both the DC brushless motor 101 and the coupling 102 are arranged at the notch to achieve a compact structure and a smaller span for the internal lead screw 105. Opposite to the brushless DC motor 101, a pipetting consumable connection portion 103, at least partially extending beyond the housing 10, is disposed at the other end of the housing 10. The pipetting consumable connection portion 103 can be configured as a rotating body, such as a cylindrical body, containing an airflow channel inside. A pipetting consumable unloading portion 104, at least partially surrounding the pipetting consumable connection portion 103, is also disposed outside the pipetting consumable connection portion 103. The pipetting consumable unloading portion 104 includes a cylindrical structure that can surround the outside of the pipetting consumable connection portion 103. The pipetting consumable unloading portion 104 is connected via the brushless DC motor. The drive of 101 enables relative axial movement with respect to the pipetting consumable connection 103, thereby generating a resisting effect on the pipetting consumable 100. This allows the same brushless DC motor 101 to meet the different operating conditions of the pipette. The drive control system 20 includes a control module 202 that is electrically connected to the brushless DC motor 101 to output the drive for its rotational motion. It also includes a sensing module 201 that can sense different parameters, thereby enabling adaptive drive of the brushless DC motor 101.To meet the demands of high torque output and high-speed operation in both pipetting and unloading scenarios, the control module 202 includes a storage unit that stores the motor speed corresponding to the scenario. The drive module 203 drives the brushless DC motor 101 to operate at a first preset speed, enabling the pipetting module to complete the aspiration / discharge action. Since the viscosity of the transferred liquid is generally not very high, the output torque of the brushless DC motor 101 does not need to be too high. Therefore, the first preset speed output by the drive module 203 can be very high to achieve rapid pipetting, thus minimizing the problem of liquid sticking to the pipette wall caused by slow pipetting speed. Here, the first preset speed is 85%-100% of the maximum allowable operating speed of the brushless DC motor 101. For example, when the maximum allowable speed is 35000... At this speed, the first preset rotational speed can be selected between 29750-35000 r / min. If the maximum allowable rotational speed is higher, the corresponding first preset rotational speed can also be higher, for example, the maximum rotational speed can be 40000 r / min, 50000 r / min, etc. If the maximum allowable rotational speed is lower, the first preset rotational speed can also be lower, for example, the maximum rotational speed can be 30000 r / min, 20000 r / min, 10000 r / min, 6000 r / min, or even 3000 r / min, etc. There is no limitation here. The ratio of the first preset rotational speed to the maximum rotational speed should not be less than 85% in order to ensure high-speed pipetting efficiency. On the other hand, it can also ensure that the liquid receives sufficient driving force during pipetting, thereby avoiding problems such as residue adhesion to the wall that exist at lower speeds. After the aspiration / dissipation operation is completed, when it is necessary to unload the pipetting consumable 100, the drive module 203 can drive the DC brushless motor 101 to run at a second preset speed so that the consumable unloading module can complete the unloading action of the pipetting consumable 100. At this time, the DC brushless motor 101 needs to apply a resisting force to the pipetting consumable unloading part 104. In order to ensure a good sealing connection between the pipetting consumable 100 and the pipetting consumable connection part 103, the pipetting consumable unloading part 104 needs to apply a sufficiently large unloading force. This requires the DC brushless motor 101 to output a considerable torque. If a stepper motor is used, a reduction mechanism is needed to achieve this. High torque output, and the brushless DC motor 101 of the present invention only needs to operate at a second speed much lower than the first preset speed to output sufficient resistance force. Here, the first preset speed is 8-500 times the second preset speed, for example, it can be a multiple of 10, 15, 20, 30, 50, 75, 80, 90, 100, 130, 150, 190, 220, 300, 350, 400, 500, etc. Of course, in some scenarios of lower speed brushless DC motor 101, the first preset speed is more than eight times the second preset speed to ensure sufficient torque to apply force to the pipetting consumable unloading part 104.

[0047] Figure 2The schematic diagram illustrates the internal structure of the pipette of the present invention. A DC brushless motor 101 is connected to a lead screw 105 within the housing 10 via a coupling 102. The lead screw 105 has a predetermined thread pitch, which can be determined based on the pipetting accuracy. A slider assembly 106 is connected to the lead screw 105. A guide rail for the slider assembly 106 is arranged substantially parallel to the axis of the lead screw 105, allowing the slider assembly 106 to slide along the axial direction of the lead screw 105. The slider assembly 106 crosses the guide rail... The other end is connected to a stopper rod 107, which is at least partially inserted into the internal cavity of the pipetting consumable connection part, forming a piston-like motion structure. Driven by the slider assembly 106, the stopper rod 107 can reciprocate within the cavity of the pipetting consumable connection part, thereby realizing the aspiration and discharging action of liquid. A contact head of the pipetting consumable unloading part 104 is arranged at the lowest position inside the housing 10. When it is necessary to unload the pipetting consumable 100, the DC brushless motor 101 drives the lead screw 105 to rotate. The DC brushless motor 101 can first move at a speed greater than... The slide block 106 rotates at a relatively high speed, and when it contacts the contact tip, the brushless DC motor 101 operates at a second preset speed. This provides a sufficiently large push-out driving force. Of course, the second preset speed is not necessarily a constant speed; it can be a decreasing or increasing speed, or even a speed fluctuating within a certain range. This is not limited here. This allows for the rapid and reliable unloading of the pipette consumable 100. To ensure the compactness and rationality of the pipette structure, the control elements of the control module 202, the drive circuit elements of the drive module 203, and the circuit elements of the sensing module 201 are all mounted on the same pipette circuit backplate 200. The circuit backplate 200 has a structure similar to the shape of the pipette and also has a notch. It can completely cover the internal structure of the pipette and is connected to the internal frame of the housing 10 by screws. This also satisfies the characteristics of easy disassembly and maintenance. The side plate of the housing 10 can be connected to its outside, thus forming a closed internal space that meets the requirements of cleanliness and electromagnetic shielding.

[0048] Figure 3This is a circuit schematic diagram of a portion of the DC brushless servo system of the present invention. The sensing module 201 includes a sensing signal processor, which is electrically connected to different sensor units. The air pressure sensor is in airflow communication with the internal cavity of the pipetting consumable connection part 103, and can sense the pressure changes caused by the movement of the plunger 107. For example, it can be used with a pipette to detect the liquid level. When the pipette contacts the liquid surface or is inserted below the liquid surface, a large positive and negative pressure fluctuation will be generated inside the cavity of the pipetting consumable connection part 103. This fluctuation is amplified by the circuit amplifier and can be recognized by the signal processing unit. Then, the liquid level position can be determined by analyzing the pressure curve. However, a pressure sensor can also assist in accurate pipetting. Generally, the working principle of an air-displacement pipette determines its basic properties as an inertial system. When the plunger 107 moves rapidly to the designated position, a negative pressure is generated in the chamber. Under the action of external atmospheric pressure, the liquid is forced into the pipetting consumable 100. By detecting the internal pressure change through a pressure sensor, the completion of the pipetting process can be determined more accurately, and the pipetting end time can be given more precisely. This also highlights the importance of a reliable and sealed connection between the pipetting consumable 100 and the pipetting consumable connection 103. If the connection is unreliable, the pipette may lose its pipetting precision. In some scenarios, a photoelectric sensor sensing unit is installed on the slider assembly 106 to limit the extreme positions of the slider assembly 106's movement, ensuring the reliability of the plunger 107's movement. Additionally, the photoelectric sensor can also detect whether the pipetting consumable is correctly connected. A temperature sensor can detect the ambient temperature. Temperature sensors can also be installed in areas with strict temperature control requirements, thus protecting critical components. Ambient temperature detection also provides optimal operating parameters for the pipette. The sensing module 201 can contain more sensor units; this is not a limitation. The sensing module is signal-connected to the control module 202, meeting the intelligent operation requirements of the pipette. The control module 202 performs signal processing and calculations, outputting control commands for the final operation of the brushless DC motor 101. These control commands are transmitted to the drive module 203 via circuitry. The circuit elements within the drive module 203 parse the control commands into the conduction control sequence of the circuit elements, ultimately loading them onto the drive phase windings of the brushless DC motor 101 to complete the drive control of the brushless DC motor 101. The position of the permanent magnet rotor during the operation of the brushless DC motor 101 can be fed back through the coded sensing unit, forming a closed-loop control.

[0049] Figure 4This is a schematic diagram of the control drive circuit for a brushless DC motor 101. The control module 202 can output control signals through signal output terminals P1, P2, and P3. Here, it can output pulse control waves with adjustable pulse width and / or frequency. When the required drive current is small, the duty cycle of the control wave can be adjusted to a very small value. The control waveform at P1 is connected to the base of transistor Q1, and after being inverted by inverter R1, it is applied in reverse to the base of transistor Q4. This forms a reliable interlocking structure, meaning that in this design, transistors Q1 and Q4 can never be turned on at the same time. Similarly, Q2 and Q5, and Q3 and Q6 are designed similarly, except that different inverters R2 and R3 are used for connection in the circuit. The driving voltage VDD can apply different driving currents to the magnetic pole windings of the brushless DC motor 101 when different transistors are turned on. The specific structure of the brushless DC motor is not described in detail here. Only the stator winding magnetic poles of the brushless DC motor 101 with different windings are schematically shown as three sets of windings A, B, and C. When the stator windings are intermittently energized in turn, the permanent magnet rotor will generate a following rotational motion in the magnetic field formed by the windings, thereby realizing the following rotation of the permanent magnet rotor.

[0050] Figure 5 This diagram illustrates the rotation principle of the permanent magnet rotor in the DC brushless motor 101 of the present invention. To enable the permanent magnet rotor to rotate within the range of 0°-60°, Figure 4 The PWM modulation signal output from P1 is input to the base of Q1. After being inverted by an inverter, the opposite control signal is applied to the base of Q4, thus achieving reliable interlocking between Q1 and Q4. The control signal output from P2 is shown as the low-level cutoff signal during the control period of phase A. After being inverted, the base of Q5 is given a high-level conduction signal, while phase C is in a floating state with no current. The rotation drive in other angle ranges is similar to the principle of 0°-60° and will not be described in detail here. In this control mode, only the duty cycle of the PWM pulse signal needs to be controlled to increase the speed of the brushless DC motor 101.

[0051] Figure 6The illustration shows the drive current detection unit of the brushless DC motor 101 of the present invention. In this embodiment, the current detection unit 2022 can be integrated on the integrated circuit board. The motor drive part adopts the MOSFET half-bridge drive method to drive the brushless DC motor 101. The principle will not be described in detail. The drive current acquisition method uses Hall sensors to collect the three-phase drive current and feed it back to the control board for closed-loop control. After receiving the current magnitude in the phase path, the control board adjusts the motor control signal to make the brushless DC motor 101 run smoothly. The encoding sensing unit 2023 uses a magnetic encoder to output an absolute position signal to the control board. The control board can accurately track the exact position of the brushless DC motor 101 based on the position signal output by the encoding sensing unit 2023. Here, the encoding sensing unit 2023 can divide the rotation circumference of the permanent magnet rotor into a scheme containing, for example, 1024 points, which can achieve precise position detection and control. In this embodiment, the current sensor can of course be arranged to collect only two phases, while the third phase can be obtained through theoretical calculation. This is not limited here. Both the encoding sensing unit 2023 and the current detection unit 2022 are connected to the control module 202, so that the entire drive control presents a closed loop. This also allows for timely and accurate matching of drive power, resulting in lower power consumption of the pipette.

[0052] Figure 8 This is a schematic diagram of the operating range of the brushless DC motor 101 of the present invention. The correlation characteristics between the rated speed and output torque of the motor under different input power are shown by the decreasing curve in the figure. Therefore, in order to adapt to different scenarios of pipette, the pipette of the present invention can obtain different torque outputs by changing the operating speed range of the brushless DC motor 101. The drive module 203 can drive the brushless DC motor 101 to run at a first preset speed so that the pipetting module can complete the aspiration / discharge action (high speed and low torque state); or the drive module 203 can drive the brushless DC motor 101 to run at a second preset speed so as to drive the pipetting consumable unloading part 104 so that the consumable loading and unloading module can complete the pipetting consumable unloading action (high torque and low speed state). In order to ensure the reliability of the operation of the brushless DC motor 101, the first preset speed is 85%-100% of the maximum speed. The first speed should not be too small mainly because sufficient negative pressure needs to be generated during pipetting to ensure the aspiration and discharge speed, and at the same time, it can also avoid the risk of contamination caused by liquid adhering to the wall due to the speed being too small. When the first preset speed is running, the input power of the brushless DC motor 101 fluctuates, but its torque output does not change by more than 40%. As a pipette, the input power of the brushless DC motor 101 can fluctuate when the output power is fixed. However, in order to meet the needs of stable and precise pipetting, the torque output of the brushless DC motor 101 should not change by more than 40% when running at the first preset speed.

[0053] To verify the advantages of the pipette of this invention, long-term aspiration / dispensing operations were conducted. After the temperature rose and stabilized, the final stable temperature was compared. The stable temperature of the DC brushless motor 101 of this invention was about 35°C, while the stable temperature of the Tiken stepper motor under the same conditions was about 70°C. This directly proves that precise speed control for different scenarios is beneficial to the design of precise pipettes and avoids the accumulation of waste heat in the instrument using the DC brushless motor 101, which would affect the experimental accuracy.

[0054] Example 3

[0055] Example 3 replaces the implementation of the current detection unit 2022 in Example 2, and is a replacement solution for Example 2; further explanation: identical components will not be described again here, such as... Figure 7 As shown in the attached figure, the magnitude of the voltage caused by the current in the sampling resistor can also be used to feed back the magnitude of the current in the circuit. In the A-phase circuit, the two ends of the voltage divider resistor R11 are connected to the positive and negative ends of the comparator respectively, and the comparison result is fed back to the control system through the negative feedback line. Similarly, the currents of the other two phases can be obtained and fed back using R12 and R13. Of course, voltage divider detection points can also be set in only two phase circuits, while the third phase can be obtained through theoretical calculation.

[0056] Example 4

[0057] A modular pipette control method driven by a DC brushless servo system, such as Figure 2 , Figure 9 As shown, it includes the following steps:

[0058] Pipetting steps: The control module 202 transmits a control signal to the drive module 203, which drives the brushless DC motor 101 to rotate at a first preset speed. The lead screw 105 rotates together with the motor shaft of the brushless DC motor 101 through the coupling 102. The sliding component on the lead screw 105 drives the stopper rod 107 to move relative to the pipetting consumable 100 connection. When the stopper rod 107 moves toward the pipetting consumable 100 connection, the volume of the pipetting cavity formed between the stopper rod 107 and the pipetting consumable 100 connection decreases, and a discharging action is performed. When the stopper rod 107 moves away from the pipetting consumable 100 connection, the volume of the pipetting cavity formed between the stopper rod 107 and the pipetting consumable 100 connection increases, and a suction action is performed.

[0059] Unloading steps: The control module 202 transmits a control signal to the drive module 203. The drive module 203 drives the DC brushless motor 101 to rotate forward at a second preset speed. The lead screw 105 rotates together with the motor shaft of the DC brushless motor 101 through the coupling 102. The sliding component on the lead screw 105 moves towards the unloading abutment. After the sliding component abuts against the unloading abutment, it acts on the unloading abutment, causing the unloading abutment to move in the direction of the pipetting consumable 100. At the same time, the unloading abutment drives the unloading sleeve to move relative to the connection part of the pipetting consumable 100, and causes the unloading sleeve to abut against the pipetting consumable 100. It continues to move until the unloading sleeve is flush or almost flush with the lower part of the sealing connection end 401 of the connection part of the pipetting consumable 100. The abutted pipetting consumable 100 falls off from the sealing connection end 401 of the connection part of the pipetting consumable 100, completing the unloading of the pipetting consumable 100.

[0060] Reset Steps: Control module 202 transmits control signals to drive module 203, drive module 203 drives brushless DC motor 101 to rotate in the opposite direction, lead screw 105 rotates together with brushless DC motor 101 through coupling 102, slider assembly 106 moves away from unloading abutment until it no longer acts on unloading abutment, unloading abutment drives unloading sleeve to reset through reset element, exposing sealing connection end 401, sealing connection end 401 can now be used to connect with new pipetting consumable 100.

[0061] The first preset speed is 8-500 times the second preset speed; the first preset speed is 85%-100% of the maximum allowable operating speed of the brushless DC motor 101; when the first preset speed is running, the input power of the brushless DC motor 101 fluctuates, and the torque output of the brushless DC motor 101 does not change by more than 40%.

[0062] The sensing module 201 is signal-connected to the control module 202. The control module 202 can adjust the speed of the brushless DC motor 101 based on the data transmitted by the sensing module 201, and send a control signal to the drive module 203, so that the drive module 203 drives the brushless DC motor 101 to rotate at a predetermined speed. The sensing module 201 includes a current detection unit 2022 and / or an encoding sensing unit 2023. The current detection unit 2022 can collect the current data values ​​of at least two phase windings in the brushless DC motor 101, and the encoding sensing unit 2023 can collect the position information data of the permanent magnet rotor in the brushless DC motor 101.

[0063] The drive control system 20 can know the current execution state of the pipette, which can be liquid aspiration, liquid dispensing, liquid level detection, unloading pipetting consumables, etc. It can be combined with the detection results of Hall position sensing unit, pressure sensing unit, etc. to make a comprehensive judgment. Based on the state, the drive control system 20 makes the modular pipette operate in one of the following modes. It should be noted that the drive control system 20 may store multiple operating modes. Under the premise that the drive control system 20 knows the current execution state, the drive control system 20 will operate in one of the two modes. When the drive control system 20 detects that the current execution state is rapid aspiration / dissipation, the drive control system 20 can drive the DC brushless motor 101 to run at a first preset speed so that the pipetting module can complete the aspiration / dissipation action, thus ensuring pipetting efficiency and reducing the risk of contamination on the pipetting wall; when the drive control system 20 detects that the current execution of the pipetting consumable unloading action is in the state where the slider assembly 106 in the pipette contacts the pipetting unloading part, the drive control system 20 can drive the DC brushless motor 101 to run at a second preset speed so that the pipetting consumable unloading part 104 can drive the consumable loading and unloading module to complete the pipetting consumable unloading action. Finally, the drive control system 20 continuously outputs drive to complete the corresponding action. Of course, the drive control system 20 can also know that the current state of the pipette is other states, such as the following pipetting state. In this case, the speed output by the control system may be related to the downward speed of the entire pipette driven by the Z-axis DC brushless motor 101. Alternatively, it may be the state in which the pipetting consumable is unloading but the slider assembly 106 has not contacted the pipette unloading part. In this case, the speed of the motor output by the control system may be close to or the same as the first preset speed to ensure that the unloading speed of the entire pipetting consumable 100 is faster.

[0064] This article uses specific embodiments to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0065] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0066] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A modular pipette driven by a DC brushless servo system, characterized in that, The system includes a drive control system, a pipetting module, a consumable loading / unloading module, and a transmission module. The drive control system can act on the pipetting module and the consumable unloading module respectively through the transmission module. The drive control system includes a drive module and a control module. The control module is signal-connected to the drive module, and the drive module is electrically connected to a brushless DC motor. The drive module can drive the brushless DC motor to act on the pipetting module at a first preset speed, so that the pipetting module can complete the aspiration / discharge action. The drive module can also drive the brushless DC motor to act on the consumable unloading module at a second preset speed, so that the consumable unloading module can complete the unloading action of the pipetting consumables. The first preset speed is... The second preset speed is 8-500 times; the first preset speed is 85%-100% of the maximum allowable operating speed of the DC brushless motor; the pipetting module includes a stopper rod and a pipetting consumable connection part, and the transmission module includes a lead screw and a slider assembly; the lead screw is provided with a slider assembly, the stopper rod is connected to the slider assembly, one end of the stopper rod is adjustablely connected to the slider assembly through a correction element with elastic properties, and the other end is at least partially inserted into the interior of the pipetting consumable connection part; the correction element is provided with a clamping element at the end connected to the stopper rod relative to the correction element, and the clamping element provides clamping force to ensure that the stopper rod is connected to the slider assembly without shaking.

2. The modular pipette driven by a DC brushless servo system as described in claim 1, characterized in that, When the first preset speed is running, the input power of the brushless DC motor fluctuates, and the torque output of the brushless DC motor changes by no more than 40%.

3. The modular pipette driven by a DC brushless servo system as described in claim 1, characterized in that, The drive control system also includes a sensing module, which is signal-connected to the control module. The sensing module and the control module transmit collected data values. The control module can transmit control signals to the drive module based on the collected data values ​​transmitted by the sensing module.

4. The modular pipette driven by a DC brushless servo system as described in claim 3, characterized in that, The sensing module includes a current detection unit, which can collect current data values ​​of at least two phase windings in the brushless DC motor. The current detection unit is connected to the control module, and the control module can transmit control signals to the drive module based on the current data values ​​transmitted by the current detection unit.

5. The modular pipette driven by a DC brushless servo system as described in claim 3, characterized in that, The sensing module includes an encoding sensing unit, which can collect position information data of the permanent magnet rotor in the brushless DC motor. The encoding sensing unit is connected to the control module, and the control module can transmit control signals to the drive module based on the position information data transmitted by the encoding sensing unit.

6. A modular pipette control method driven by a DC brushless servo system, applied to the modular pipette as described in any one of claims 1-5, characterized in that, Includes the following steps: Pipetting steps: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate at a first preset speed. The lead screw rotates together with the motor shaft of the brushless DC motor through a coupling. The slider assembly on the lead screw drives the plunger to move relative to the pipetting consumable connection part. When the plunger moves towards the pipetting consumable connection part, the volume of the pipetting cavity formed between the plunger and the pipetting consumable connection part decreases, and the dispensing action is performed. When the plunger moves away from the pipetting consumable connection part, the volume of the pipetting cavity formed between the plunger and the pipetting consumable connection part increases, and the aspiration action is performed. Unloading steps: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate forward at a second preset speed. The lead screw rotates together with the motor shaft of the brushless DC motor through a coupling. The slider assembly on the lead screw moves toward the unloading abutment. After the slider assembly abuts against the unloading abutment, it acts on the unloading abutment, causing the unloading abutment to move toward the direction of the pipetting consumable. At the same time, the unloading abutment drives the unloading sleeve to move relative to the pipetting consumable connection part, and causes the unloading sleeve to abut against the pipetting consumable. It continues to move until the unloading sleeve is flush with or almost flush with the lower part of the sealing connection end of the pipetting consumable connection part. The pipetting consumable that is abutted falls off from the sealing connection end of the pipetting consumable connection part, completing the unloading of the pipetting consumable. Reset Procedure: The control module transmits a control signal to the drive module, which drives the brushless DC motor to rotate in the opposite direction. The lead screw rotates with the brushless DC motor through the coupling. The slider assembly moves away from the unloading abutment until it no longer acts on the unloading abutment. The unloading abutment is reset by the reset element, which drives the unloading sleeve to reset, exposing the sealing connection end. The sealing connection end can now be used to connect to a new pipetting consumable.

7. The modular pipette control method driven by a DC brushless servo system as described in claim 6, characterized in that, The first preset speed is 8-500 times the second preset speed, and / or the first preset speed is 85%-100% of the maximum allowable operating speed of the brushless DC motor, and / or when the first preset speed is running, the input power of the brushless DC motor fluctuates, and the torque output of the brushless DC motor does not change by more than 40%.

8. The modular pipette control method driven by a DC brushless servo system as described in claim 6, characterized in that, The sensing module is signal-connected to the control module. The control module can adjust the speed of the brushless DC motor based on the data transmitted by the sensing module and send a control signal to the drive module, so that the drive module drives the brushless DC motor to rotate at a predetermined speed. The sensing module includes a current detection unit and / or an encoding sensing unit. The current detection unit can collect the current data values ​​of at least two phase windings in the brushless DC motor, and the encoding sensing unit can collect the position information data of the permanent magnet rotor in the brushless DC motor.

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