A speed-adjustable handheld pipette

Abstract

A speed-adjustable handheld pipette comprises an upper shell and an intermediate shell. A liquid volume adjustment sleeve is sleeved on the inner side of the upper shell. A driven sleeve is inserted into the other end of the liquid volume adjustment sleeve. An internal thread is provided on the bottom inner wall of the driven sleeve. A speed adjustment unit is provided in the intermediate shell. The speed adjustment unit comprises a throttling device arranged at the top of the internal volume of an upper control chamber. The throttling device can rotate relative to the upper control chamber to change the cross-sectional area of ​​the first upper opening of the discharge channel connected to the upper control chamber.

Description

Technical Field

[0001] The invention relates to a speed-adjustable pipette, in particular to a speed-adjustable handheld pipette, and belongs to the technical field of analytical chemistry. Background Art

[0002] Handheld pipettes are particularly used in laboratories for measuring liquids, with the liquid being drawn in and out of the pipette tip. The operator presses a pressure cap to change the volume of the air cushion. In air-cushion-type handheld pipettes, a gas plunger is integrated into the pipette and communicates with at least one pipette tip. The air cushion is reciprocated by the plunger, allowing working fluids or reagents to be drawn into and discharged from the pipette tip. The device for removably attaching at least one pipette tip is conical, facilitating the aspiration of working fluids or reagents.

[0003] The pipette tip is detachably connected to the handheld pipette, allowing it to be replaced after use, thus avoiding contamination of the reagents caused by using different working solutions or reagents. The pipette tip is a standard component on the market and is made of corrosion-resistant plastic. In some special applications, metal materials are used.

[0004] The prior art patent with publication number CN101912794A describes a pipette. When a reagent or working liquid is sucked, the driving device is pressed, and the driving device drives the lifting rod to move downward along the corresponding guide sleeve. The lifting rod acts on the end face of the plunger, causing the plunger to move downward to change the cavity volume of the displacement device. At the same time, the plunger return spring is compressed and is in a compressed state. When the tip of the suction tube contacts the working liquid or reagent, the plunger moves upward under the action of the plunger return spring, and the working liquid or reagent is sucked into the tip of the suction tube by utilizing the negative pressure principle. However, there is a very small possibility that the working liquid or reagent is sucked into the displacement device with the pipette. Usually, the plunger is under the action of the return spring. If no force is applied to the plunger, the plunger will move up too quickly, causing a large amount of working fluid or reagent to be sucked into the tip of the pipette. At this time, the liquid has a certain kinetic energy. Under low conditions, the liquid will splash into the displacement device and adhere to the inner wall of the cavity of the displacement device. When the liquid is transparent, it is difficult for the operator to find the adhesion of the reagent or working fluid to the inner wall of the cavity; even if the adhesion of the inner wall of the cavity is found, it will bring corresponding cleaning workload, which is not conducive to the continuity of the extraction of the working fluid or reagent; at the same time, in the next aspiration process, the reagent attached to the inner wall of the cavity will be transported to the pipette tip as the plunger moves down, causing contamination of the reagent or working fluid and affecting the analysis of the experimental results. Summary of the Invention

[0005] The object of the present invention is to provide a speed-adjustable handheld pipette, which is equipped with a variable throttling device to control the return speed of the plunger rod at different aspiration amounts, thereby preventing the working fluid from entering the pipette gun and causing contamination during the extraction of different working fluids or reagents, thereby affecting the analysis of experimental results; by setting the variable throttling device to have different plunger rod upward movement speeds at different aspiration amounts, not only can the contamination of the pipette device by splashing during reagent extraction be prevented, but the aspiration efficiency can also be improved; at the same time, the variable throttling device can realize the rapid upward movement of the plunger rod at smaller aspiration amounts, thereby improving the reagent aspiration efficiency.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] The present invention provides a handheld pipette, comprising an upper shell, an intermediate shell and a lower shell, wherein a liquid volume adjusting sleeve is sleeved on the inner side of the upper shell, and the liquid volume adjusting sleeve can be rotatably moved relative to the upper shell, and the liquid volume adjusting sleeve can be fixed in the upper shell by means of an axis limit of a bearing or a limiting boss, etc., and an adjusting roller is integrally connected to the end of the liquid volume adjusting sleeve extending out of the upper shell, and a driven sleeve is sleeved on the other end of the liquid volume adjusting sleeve, and one end of the driven sleeve has a diameter smaller than the inner diameter of the liquid volume adjusting sleeve, so that the driven sleeve is inserted into the other end of the liquid volume adjusting sleeve, and the driven sleeve and the liquid volume adjusting sleeve rotate together to transmit the torque during the adjustment process; an adjusting nut is sleeved on the inner side of the driven sleeve, and the adjusting nut rotates with the driven sleeve; a non-rotatable sleeve of the lead screw nut is arranged on the driving rod, and the driving rod can slide up and down relative to the lead screw nut, and a boss is provided on the driving rod to engage with the lead screw nut The lower end surface of the driven sleeve abuts, an external thread is provided at the bottom of the driven sleeve, and the mechanical counter adjusts the counting by meshing with the external thread through a gear set, and an internal thread is provided on the bottom inner wall of the driven sleeve, and a speed adjustment unit is provided in the intermediate shell, and the speed adjustment unit includes an upper control chamber and a lower control chamber formed by a piston fixedly sleeved on the plunger rod, and at least one discharge channel and at least one inflow channel connected to the upper control chamber and the lower control chamber, and a throttling device is provided at the top of the internal volume of the upper control chamber, which can rotate relative to the upper control chamber to change the cross-sectional area of ​​the first upper opening of the discharge channel connected to the upper control chamber, so that at different aspiration amounts, the discharge channel is controlled to have different flow capacities to achieve different plunger rod upward movement speeds, which can not only prevent the contamination of the handheld pipette by splashing during reagent extraction, but also improve the aspiration efficiency of the handheld pipette.

[0008] Furthermore, the intermediate shell and the upper shell are sealed and connected, preferably by means of threaded connection, clamping, bonding, etc.; the lower shell and the intermediate shell are sealed and connected, preferably by means of threaded connection, clamping, bonding, etc.; the bottom of the lower shell is fixedly connected to a displacement device, a cavity is formed in the displacement device to cooperate with the plunger rod, and a suction head is connected to the bottom of the displacement device, which is preferably a KG series suction head produced by KIRGEN.

[0009] Furthermore, the handheld pipette also includes an upper cover plate and a lower cover plate arranged in the intermediate shell, the upper cover plate and the movable piston form the upper control chamber, and the lower cover plate and the movable piston form the lower control chamber, and the upper cover plate and the lower cover plate are sealed and arranged in the intermediate shell. In order to facilitate the installation of the upper cover plate and the lower cover plate, the upper cover plate and the lower cover plate can be installed by threaded connection, clamping, bonding, etc., and any method suitable for sealing the upper cover plate and the lower cover plate with the intermediate shell in the prior art can be applied.

[0010] Furthermore, the at least one inflow channel is arranged in the plunger rod, and a one-way valve is provided in the inflow channel to prevent the fluid in the upper control chamber from flowing into the lower control chamber through the inflow channel during the upward movement of the plunger rod. The one-way valve can adopt a ball valve design with a spring, and other valve forms that realize one-way flow in the prior art can be applied to the inflow channel. The second upper opening of the inflow channel located in the plunger rod is located in the upper control chamber, and the second lower opening of the inflow channel located in the plunger rod is located in the lower control chamber; preferably, the second upper opening and the second lower opening are arranged adjacent to the piston, so as to ensure that the upper control chamber and the lower control chamber have a smaller axial length, and the axial lengths of the upper control chamber and the lower control chamber are set, which can ensure that when the handheld pipette is at the maximum scale or maximum suction volume, the second upper opening of the inflow channel is located on the lower side of the upper cover plate, and the second lower opening of the inflow channel is located on the upper side of the lower cover plate, so that the second upper opening and the second lower opening are located in the corresponding upper control chamber or lower control chamber regardless of how the suction volume is adjusted, thereby preventing the second upper opening and the second lower opening from falling out of the control chamber during the movement of the plunger rod, causing liquid leakage.

[0011] Furthermore, at least one inflow channel can be arranged in the peripheral wall of the intermediate shell, and the second upper opening of the inflow channel located in the peripheral wall of the intermediate shell is located in the upper control chamber, and the second lower opening of the inflow channel located in the peripheral wall of the intermediate shell is located in the lower control chamber; the second upper opening is adjacent to the lower side of the upper cover plate, and the second lower opening is adjacent to the upper side of the lower cover plate. Such an arrangement can make full use of the volume of the upper control chamber and the lower control chamber, reduce the axial length of the upper control chamber and the lower control chamber, so that the second upper opening and the second lower opening are located in the corresponding upper control chamber or the lower control chamber regardless of how the suction amount is adjusted, and prevent the second upper opening and the second lower opening from being located in the same control chamber during the movement of the plunger rod. For example, when the plunger rod moves up, the position of the second upper opening is set lower, which easily causes the second upper opening to be connected to the lower control chamber, thereby closing the fluid in the upper control chamber and forming a rigid volume, causing the plunger rod to be unable to move up to complete the predetermined reagent absorption.

[0012] Furthermore, at least one discharge channel can be provided in the peripheral wall of the intermediate shell, and the first upper opening of the discharge channel located in the peripheral wall of the intermediate shell is located in the upper control chamber, and the first lower opening of the discharge channel located in the peripheral wall of the intermediate shell is located in the lower control chamber. The inflow channel and the discharge channel can be formed by 3D printing or by setting a seal after drilling in the intermediate shell; the first upper opening is adjacent to the lower side of the upper cover plate, and the first lower opening is adjacent to the upper side of the lower cover plate. Such an arrangement can make full use of the volume of the upper control chamber and the lower control chamber, reduce the axial length of the upper control chamber and the lower control chamber, so that the first upper opening and the first lower opening are located in the corresponding upper control chamber or the lower control chamber regardless of how the aspiration amount is adjusted, and prevent the first upper opening and the first lower opening from being located in the same control chamber during the movement of the plunger rod. For example, when the plunger rod moves upward, the position of the first upper opening is set too low, which easily causes the first upper opening to communicate with the lower control chamber, thereby closing the fluid in the upper control chamber and forming a rigid volume, which makes it impossible for the plunger rod to move upward to complete the predetermined reagent aspiration. A throttling device is provided at the first upper opening, and the throttling device is rotatable relative to the upper control chamber.

[0013] Furthermore, the throttling device is in the shape of a circular ring, and a gear ring is provided on the inner upper part of the throttling device. An opening portion is provided on the side wall of the throttling device located below the gear ring. The throttling device is driven to rotate in the upper control chamber via a transmission device, and the flow area between the first opening and the upper control chamber is changed through the opening portion to limit the flow of the discharge channel, thereby realizing the adjustment of the upward movement speed of the plunger rod.

[0014] Furthermore, the transmission device includes multiple gears and a first gear shaft and a second gear shaft. The gear at the upper end of the first gear shaft is connected to the internal thread of the driven sleeve; the first gear shaft receives the adjustment torque through the gear at the upper end of the first gear shaft and rotates, driving the second gear shaft to rotate, and the lower end gear of the second gear shaft engages with the ring gear of the throttling device, driving the throttling device to rotate in the upper control chamber. By associating the throttling device with the adjustment of the suction amount, the flow area between the throttling device and the first upper opening is changed when adjusting the suction amount of the handheld pipette, so that different fluid flow areas can be achieved for different suction amounts. When the handheld pipette is controlled to a maximum suction amount, the plunger rod moves upward faster under the action of the plunger spring, and the maximum suction amount is easier to enter the displacement device. Therefore, when the maximum suction amount is set, a smaller flow area is provided, which slows down the upward movement of the plunger rod and prevents the reagent from splashing into the displacement device. When the handheld pipette is controlled to a smaller suction amount, since the level of the sucked reagent is farther than the displacement device, the throttling device can be controlled to rotate at a smaller suction amount, resulting in a larger flow area, accelerating the upward movement of the plunger rod and reducing the time for sucking the reagent. The throttling device is associated with the suction amount adjustment through the transmission device, so that the suction amount and the opening of the throttling device correspond one to one, without the need for a separate throttling device adjustment, which is both convenient and quick.

[0015] Furthermore, since the level of the absorbed reagent is farther than the displacement device when the aspiration volume is smaller, it can be set within a smaller aspiration volume range to always maintain the maximum flow area. When it is within a larger aspiration volume range, since the throttling device has limited the upward movement speed of the plunger rod, the splashing of the reagent during aspiration is well suppressed. When it is set within the maximum aspiration volume range, the throttling device limits the first upper opening to always be at the minimum position; when it is within the intermediate aspiration volume range, the opening portion of the throttling device is controlled to have a setting that decreases as the aspiration volume increases. The throttling device limits the flow area of ​​the first upper opening. When the suction volume is in a smaller range, the flow area of ​​the opening portion of the throttling device is always at a maximum value as the suction volume increases, and the opening portion of this section has a rectangular shape; when the suction volume is adjusted to an intermediate range, the flow area of ​​the opening portion of the throttling device is in a decreasing state as the suction volume increases, and the opening portion of this section has a trapezoidal shape. It can be understood that other shapes of the opening portion that can be reduced, such as triangle, cone, and semi-ellipse, are all possible; when the suction volume is adjusted to a larger range, the flow area of ​​the opening portion of the throttling device is always at a minimum value as the suction volume increases.

[0016] Furthermore, by adjusting the transmission ratio of the transmission device, when the suction amount is minimum, the first upper opening is located at the rightmost side of the opening portion, and when the suction amount is maximum, the first upper opening is located at the leftmost side of the opening portion.

[0017] Furthermore, the larger suction volume range is greater than or equal to two-thirds of the maximum suction volume of the handheld pipette, the intermediate suction volume range is less than two-thirds of the maximum suction volume of the handheld pipette and greater than one-third of the maximum suction volume of the handheld pipette, and the smaller suction volume range is less than or equal to one-third of the maximum suction volume of the handheld pipette.

[0018] The technical effects of the present invention are fully described in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0021] Figure 3 yes Figure 1 A partial enlarged schematic diagram of point B in the middle;

[0022] Figure 4 It is a structural diagram of the throttling device in the present invention;

[0023] Figure 5 It is a schematic diagram of the expansion of the throttling device in the present invention. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1-5 A schematic diagram of the overall structure of the handheld pipette is shown, which is used to illustrate the technical features of the improvements related to the present application. As for other technical features of the handheld pipette, such as the limiting device of the driving rod and the plunger rod, they are not related to the improvements related to the present application and are not displayed.

[0026] Reference Figure 1 and Figure 2The present invention provides a handheld pipette, comprising an upper shell 1, an intermediate shell 2 and a lower shell 3. A liquid volume regulating sleeve 11 is sleeved on the inner side of the upper shell 1. The liquid volume regulating sleeve 11 can rotate and move relative to the upper shell 1. The liquid volume regulating sleeve 11 can be fixed in the upper shell 1 by means of an axis limiting bearing or a limiting boss. An adjusting roller 12 is integrally connected to one end of the liquid volume regulating sleeve 11 extending out of the upper shell, and a driven sleeve 13 is sleeved on the other end of the liquid volume regulating sleeve 11. The diameter of one end of the movable sleeve 13 is smaller than the inner diameter of the liquid quantity regulating sleeve 11, so that the driven sleeve 13 is inserted into the other end of the liquid quantity regulating sleeve 11, and the driven sleeve 13 and the liquid quantity regulating sleeve 11 rotate together to transmit the torque during the adjustment process; an adjusting nut 14 is sleeved on the inner side of the driven sleeve 13, and the adjusting nut 14 rotates together with the driven sleeve 13; a non-rotatable sleeve of the lead screw nut 15 is set on the driving rod 4, and the driving rod 4 can slide up and down relative to the lead screw nut 15, and a convex The platform 41 abuts against the lower end surface of the lead screw nut 15, and the bottom of the driven sleeve 13 is provided with an external thread. The mechanical counter 5 adjusts the counting by meshing with the external thread through a gear set. The inner wall of the bottom of the driven sleeve 13 is provided with an internal thread. A speed adjustment unit is provided in the intermediate housing 2, and the speed adjustment unit includes an upper control chamber 22 and a lower control chamber 24 separated by a piston 23 fixedly sleeved on the plunger rod 7, and at least one discharge channel 26 and at least one inflow channel 27 connected to the upper control chamber and the lower control chamber. A throttling device 28 is provided at the top of the internal volume of the upper control chamber 22, and the throttling device 28 can rotate relative to the upper control chamber 22 to change the cross-sectional area of ​​the first upper opening of the discharge channel 26 connected to the upper control chamber, so that at different aspiration amounts, the discharge channel is controlled to have different flow capacities to achieve different plunger rod upward movement speeds, which can not only prevent the contamination of the handheld pipette by splashing during reagent extraction, but also improve the aspiration efficiency of the handheld pipette.

[0027] Furthermore, the intermediate shell 2 is sealedly connected to the upper shell 1, preferably by means of threaded connection, clamping, bonding, etc.; the lower shell 3 is sealedly connected to the intermediate shell 2, preferably by means of threaded connection, clamping, bonding, etc.; the bottom of the lower shell 1 is fixedly connected to a displacement device 31, and a cavity is formed in the displacement device 31 to cooperate with the plunger rod 7, and a suction head is connected to the bottom of the displacement device 31, which is preferably a KG series suction head produced by KIRGEN.

[0028] Furthermore, the handheld pipette also includes an upper cover plate 21 and a lower cover plate 25 arranged in the intermediate shell 2, the upper cover plate 21 and the movable piston 23 form the upper control chamber 22, and the lower cover plate 25 and the movable piston 23 form the lower control chamber 24, the upper cover plate 21 and the lower cover plate 25 are sealed and arranged in the intermediate shell 2, in order to facilitate the installation of the upper cover plate 21 and the lower cover plate 25, the upper cover plate 21 and the lower cover plate 25 can be installed by threaded connection, clamping, bonding and other installation methods, and any method suitable for sealing connection between the upper cover plate 21 and the lower cover plate 25 and the intermediate shell 2 in the prior art can be applied.

[0029] Furthermore, the at least one inflow channel 27 is arranged in the plunger rod 7, and a one-way valve 30 is provided in the inflow channel 27 to prevent the fluid in the upper control chamber 22 from flowing into the lower control chamber 24 through the inflow channel 27 during the upward movement of the plunger rod 7. The one-way valve 30 can be designed as a ball valve with a spring, and other valve forms that realize one-way flow in the prior art can be applied to the inflow channel 27. The second upper opening of the inflow channel 27 located in the plunger rod 7 is located in the upper control chamber 22, and the second lower opening of the inflow channel 27 located in the plunger rod 7 is located in the lower control chamber 24; preferably, the second upper opening and the second lower opening are arranged adjacent to the piston 23, so as to ensure that the upper control chamber 22 and the lower control chamber 24 have a smaller axial length, and the axial lengths of the upper control chamber 22 and the lower control chamber 24 are set, which can ensure that when the handheld pipette is at the maximum scale or maximum suction volume, the second upper opening of the inflow channel is located on the lower side of the upper cover plate 21, and the second lower opening of the inflow channel is located on the upper side of the lower cover plate, so that the second upper opening and the second lower opening are located in the corresponding upper control chamber 22 or the lower control chamber 24 regardless of how the suction volume is adjusted, thereby preventing the second upper opening and the second lower opening from falling out of the control chamber during the movement of the plunger rod 7, causing liquid leakage.

[0030] Furthermore, at least one inflow channel 27 can be provided in the peripheral wall of the intermediate housing, the second upper opening of the inflow channel 27 located in the peripheral wall of the intermediate housing is located in the upper control chamber 22, and the second lower opening of the inflow channel 27 located in the peripheral wall of the intermediate housing is located in the lower control chamber 24; the second upper opening is adjacent to the lower side of the upper cover plate 21, and the second lower opening is adjacent to the upper side of the lower cover plate 25. This arrangement can make full use of the volume of the upper control chamber 22 and the lower control chamber 24, reducing the volume of the upper control chamber 22 and the lower control chamber 24. The axial length of the second upper opening and the second lower opening is arranged so that no matter how the aspiration amount is adjusted, they are located in the corresponding upper control chamber 22 or the lower control chamber 24, thereby preventing the second upper opening and the second lower opening from being located in the same control chamber during the movement of the plunger rod 7. For example, when the plunger rod 7 moves upward, the position of the second upper opening is set too low, which easily leads to the second upper opening being connected to the lower control chamber 24, thereby closing the fluid in the upper control chamber 22 and forming a rigid volume, which makes it impossible for the plunger rod 7 to move upward to complete the predetermined reagent aspiration.

[0031] Furthermore, at least one discharge channel 26 can be provided in the peripheral wall of the intermediate housing 2, wherein the first upper opening 261 of the discharge channel 26 located in the peripheral wall of the intermediate housing 2 is located in the upper control chamber 22, and the first lower opening of the discharge channel 26 located in the peripheral wall of the intermediate housing is located in the lower control chamber 24. The discharge channel 26 can be formed by 3D printing or by setting a seal after drilling in the intermediate housing; the first upper opening 261 is adjacent to the lower side of the upper cover plate 21, and the first lower opening is adjacent to the upper side of the lower cover plate 25. This arrangement can make the best use of the upper control chamber 22 and the lower control chamber 24. The volume of the upper control chamber 22 and the lower control chamber 24 is reduced, so that the first upper opening and the first lower opening are located in the corresponding upper control chamber 22 or lower control chamber 24 regardless of how the aspiration amount is adjusted. This prevents the first upper opening and the first lower opening from being located in the same control chamber during the movement of the plunger rod 7. For example, when the plunger rod 7 moves upward, the first upper opening is positioned too low, which can easily cause the first upper opening to communicate with the lower control chamber 24, thereby sealing the fluid in the upper control chamber 22 and forming a rigid volume, which prevents the plunger rod 7 from moving upward to complete the predetermined reagent aspiration. A throttling device 28 is provided at the first upper opening 261, and the throttling device 28 can rotate relative to the upper control chamber 22.

[0032] Furthermore, the throttling device 28 is in a circular ring shape, and a gear ring 281 is provided on the inner upper part of the throttling device 28. An opening portion 282 is provided on the side wall of the throttling device 28, which is located below the gear ring 281. The throttling device 28 is driven to rotate in the upper control chamber 22 via a transmission device, and the flow area between the first opening 261 and the upper control chamber 22 is changed through the opening portion 282 to limit the flow of the discharge channel, thereby realizing the adjustment of the upward movement speed of the plunger rod 7.

[0033] Further, refer to Figure 3 The transmission device includes multiple gears and a first gear shaft 61 and a second gear shaft 62. The gear at the upper end of the first gear shaft 61 is connected to the internal thread of the driven sleeve 13; the first gear shaft 61 receives the adjustment torque through the gear at the upper end of the first gear shaft 61 and rotates, driving the second gear shaft 62 to rotate, and the lower end gear of the second gear shaft 62 is engaged with the ring gear 281 of the throttling device 28, driving the throttling device 28 to rotate in the upper control chamber 22. By associating the throttling device with the adjustment of the suction volume, the flow area between the throttling device and the first upper opening 261 is changed when adjusting the suction volume of the handheld pipette, thereby achieving different fluid flow areas for different suction volumes. When the handheld pipette is controlled to a maximum suction volume, the plunger rod 7 moves upward faster under the action of the plunger spring, and the maximum suction volume is more easily entered into the displacement device 31. Therefore, when the maximum suction volume is set, a smaller flow area is provided, which slows down the upward movement of the plunger rod 7 and prevents the reagent from splashing into the displacement device 31. When the handheld pipette is controlled to a smaller suction volume, since the level of the sucked reagent is farther than the displacement device 31, the throttling device can be controlled to rotate at a smaller suction volume, thereby having a larger flow area, accelerating the upward movement of the plunger rod and reducing the time it takes to suck the reagent. The throttling device 28 is associated with the suction volume adjustment through the transmission device, so that the suction volume and the opening of the throttling device correspond one to one, eliminating the need for separate adjustment of the throttling device 28, which is both convenient and quick.

[0034] Further, refer to Figure 5 Since the level of the absorbed reagent is farther than the displacement device 31 when the aspiration volume is small, it can be set within a small aspiration range to always maintain the maximum flow area. When it is in a large aspiration range, since the throttling device 28 has limited the upward movement speed of the plunger rod 7, the splashing of the reagent during aspiration is well suppressed. When it is set within the maximum aspiration range, the throttling device 28 limits the first upper opening 261 to always be at the minimum position; when it is in the middle aspiration range, the opening portion 282 of the throttling device 28 is controlled to have a setting that decreases as the aspiration volume increases. Figure 5The throttling device 28 limits the flow area of ​​the first upper opening 261 when the suction amount is different. When the suction amount is smaller, the flow area of ​​the opening 282 of the throttling device 28 is always at the maximum value as the suction amount increases. Figure 5 The A section in the figure indicates that the opening of the section has a rectangular shape. When the suction volume is adjusted to the intermediate suction volume range, the opening 282 of the throttling device 28 is set to a decreasing flow area as the suction volume increases, such as Figure 5 The B section in FIG. 2 shows that the opening 282 of the section has a trapezoidal shape. It is understood that other opening shapes that can be reduced, such as triangle, cone, and semi-ellipse, are also possible. When the suction volume is adjusted to a larger suction volume range, the opening 282 of the throttling device 28 is always at the minimum flow area as the suction volume increases, such as Figure 5 As shown in section C of .

[0035] Furthermore, by adjusting the transmission ratio of the transmission device, when the suction amount is minimum, the first upper opening 261 is located at the rightmost side of the opening 282 , and when the suction amount is maximum, the first upper opening 261 is located at the leftmost side of the opening 282 .

[0036] Furthermore, the larger suction volume range is greater than or equal to two-thirds of the maximum suction volume of the handheld pipette, the intermediate suction volume range is less than two-thirds of the maximum suction volume of the handheld pipette and greater than one-third of the maximum suction volume of the handheld pipette, and the smaller suction volume range is less than or equal to one-third of the maximum suction volume of the handheld pipette.

[0037] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A speed-adjustable handheld pipette, characterized in that: The cam is provided with a plurality of springs, each of which is connected to the cam body by a plurality of springs, and the plurality of springs are connected to the cam body by a plurality of springs. an upper control chamber and a lower control chamber, at least one discharge channel and at least one inflow channel communicating with the upper and lower control chambers, a throttling device being provided at the top of the internal volume of the upper control chamber, the throttling device being driven to rotate in the upper control chamber via a transmission device, changing the flow area of ​​the first upper opening communicating with the discharge channel in the upper control chamber, thereby controlling the discharge channel to have different flow capacities and realizing different upward movement speeds of the plunger rod at different suction volumes; the throttling device being in the shape of a circular ring, a gear ring being provided at the upper inner portion of the throttling device, an opening being provided at the side wall of the throttling device at the lower portion of the gear ring, the opening being composed of three sections, namely, a section with a smaller suction volume, a section with an intermediate suction volume, and a section with a larger suction volume, the section with a trapezoidal opening, and a one-way valve being provided in the inflow channel; In the relatively small suction range, as the suction increases, the flow area restricted by the opening of the throttling device is always at its maximum value; In the middle suction range, as the suction volume increases, the flow area restricted by the opening of the throttling device is in a decreasing state; In the larger suction range, as the suction increases, the flow area restricted by the opening of the throttling device is always at a minimum value; The transmission device includes multiple gears and a first gear shaft and a second gear shaft. The gear at the upper end of the first gear shaft is connected to the internal thread of the driven sleeve; the first gear shaft receives the adjustment torque through the gear at the upper end of the first gear shaft and rotates, driving the second gear shaft to rotate, and the lower end gear of the second gear shaft is engaged with the ring gear of the throttling device.

2. The speed-adjustable handheld pipette according to claim 1, wherein: The at least one inflow channel is disposed within the plunger rod.

3. The speed-adjustable handheld pipette according to claim 1, wherein: The second upper opening of the inflow channel in the plunger rod is located in the upper control chamber, the second lower opening of the inflow channel in the plunger rod is located in the lower control chamber, and the second upper opening and the second lower opening are arranged adjacent to the piston.

4. The speed-adjustable handheld pipette according to claim 1, wherein: The at least one inflow channel is arranged in the peripheral wall of the intermediate shell, the second upper opening of the inflow channel in the peripheral wall of the intermediate shell is located in the upper control chamber, and the second lower opening of the inflow channel in the peripheral wall of the intermediate shell is located in the lower control chamber.

5. The speed-adjustable handheld pipette according to claim 4, wherein: The second upper opening is adjacent to the lower side of the upper cover plate, and the second lower opening is adjacent to the upper side of the lower cover plate.

6. The speed-adjustable handheld pipette according to claim 1, wherein: In the smaller suction amount section and the larger suction amount section, the flow area of ​​the first upper opening restricted by the opening portion remains unchanged as the suction amount is adjusted.

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