A high-precision syringe pump

Abstract

The application provides a high-precision injection pump, and belongs to the technical field of fluid delivery, which comprises a pump body support, a rotary valve and a lead screw, the pump body support is provided with a supporting plate, an upper support and a lower support, the upper support is vertically arranged at the upper end of the supporting plate, and the lower support is vertically arranged at the lower end of the supporting plate; the two ends of the lead screw are rotationally connected with the upper support and the lower support respectively, the lead screw is connected with a second stepping motor through a transmission mechanism; a lead screw nut is threadedly connected with the lead screw, the lead screw nut is connected with the piston of a syringe; and an elastic member is arranged between the lead screw and the upper support or the lower support. The high-precision injection pump is provided with the elastic member between the lead screw and the upper support or the lower support, the axial clearance of the lead screw is eliminated, the zero-clearance lead screw nut which can be radially contracted and the double-rail guide are combined, the precision of the lead screw transmission is guaranteed, and the accuracy and stability of liquid transmission are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid delivery, in particular to a high-precision syringe pump. BACKGROUND

[0002] In some experiments, such as the process of liquid chromatography analysis, a high-precision syringe is needed to deliver liquid, including sampling and sample dispensing processes. The driving of the syringe is generally achieved by using a driving mechanism or device, among which the syringe pump is most commonly used. In the case where the liquid delivery amount must be very accurate, the total amount is very small, the liquid delivery speed needs to be slow or constant for a long time, a high-precision syringe pump should be used to achieve this purpose.

[0003] In the prior art, a high-precision syringe pump is usually composed of a stepping motor, a lead screw, a nut support, etc. The nut reciprocates, the nut is connected to the piston of the syringe, the syringe contains the liquid medicine, and the high-precision, smooth and pulsation-free liquid delivery is achieved. In the traditional technology, the syringe pump injection mechanism adopts a single lead screw and a fixed lead screw nut mechanism. The lead screw nut is directly connected to the syringe piston, and the reciprocating movement of the syringe piston is driven by the rotation of the lead screw to achieve liquid injection.

[0004] At present, the main shortcomings of the traditional syringe pump are that the gap between the lead screw and the lead screw nut increases with time, which reduces the precision of the reciprocating movement of the syringe piston and cannot ensure constant infusion precision; the fixed lead screw nut cannot automatically compensate for wear and tear and can only be replaced periodically, increasing the cost of use.

[0005] In order to solve the problem of increasing gap, a Chinese invention patent with application number 20150734221.6 provides an automatic reversible liquid phase syringe pump, which comprises a pump body, a frame, a moving seat, a reversible stepping motor, a guide shaft, a transmission lead screw, a gap-eliminating nut assembly, a linear bearing, a syringe coupling screw, a linear transmission stepping motor, a synchronous pulley with a rim, a synchronous belt, and a synchronous pulley without a rim. The scheme solves the permanent precision fit between the nut and the lead screw by designing the nut to be tightened at any time under the action of the spring, thereby ensuring the precision and stability of the high-precision syringe pump during use.

[0006] However, the automatic reversible liquid phase syringe pump provided in the above technical solution only eliminates the gap between the nut and the lead screw. In actual use, in addition to the possible increase in the gap between the lead screw and the nut, the gap between the lead screw and the support will also increase, causing the lead screw to float in the axial direction and causing the precision of the lead screw and the nut to decrease during the reciprocating movement of the syringe piston. SUMMARY

[0007] Therefore, the present application aims to solve the technical problem of overcoming the precision decline of the high-precision injection pump in the prior art, thereby providing a high-precision injection pump capable of overcoming the above-mentioned defects.

[0008] To solve the above technical problems, the technical solutions provided by the present application are as follows:

[0009] A high-precision injection pump, comprising:

[0010] A pump body support;

[0011] A lead screw, both ends of which are rotatably installed in the pump body support through a first bearing and a second bearing, respectively, and which is connected to the second stepper motor;

[0012] A lead screw nut, which is threadedly connected to the lead screw and is connected to the piston of the syringe;

[0013] An elastic member, which is arranged between the first bearing and the pump body support or between the second bearing and the pump body support, one end of which abuts against the end face of the first bearing or the second bearing, and the other end of which abuts against the pump body support.

[0014] As an optional technical solution, the upper end of the lead screw is installed on the pump body support through the first bearing, the elastic member is arranged between the first bearing and the pump body support, and the second stepper motor is connected to the lower end of the lead screw.

[0015] As an optional technical solution, the present application further comprises:

[0016] A sliding block, which is fixedly installed with the lead screw nut, and a push rod connected to the sliding block, one end of the push rod extending out of the pump body support through a strip-shaped through hole formed in the pump body support and being connected to the piston of the syringe.

[0017] As an optional technical solution, the present application further comprises:

[0018] Two guide rods, which are fixedly connected to the pump body support, are arranged in parallel with the lead screw, and the sliding block is slidingly installed on the guide rods.

[0019] As an optional technical solution, one end of one of the two guide rods is fixedly connected to the pump body support;

[0020] One end of the other guide rod is fixedly connected to the pump body support, and the other end is inserted into a plug hole in the pump body support, and a gap is formed between the other end and the bottom wall of the plug hole.

[0021] As an optional technical solution, the present application further comprises:

[0022] The guide sleeve is fixedly installed on the sliding block, and the guide rod passes through the guide sleeve and is in sliding fit with the guide sleeve.

[0023] As an optional technical solution, the two guide rods are located in the same plane as the lead screw, and the two guide rods are symmetrically arranged on the two sides of the lead screw.

[0024] As an optional technical solution, the material of the nut is engineering plastic.

[0025] As an optional technical solution, further comprising:

[0026] The rotary valve is installed on the pump body support, and the rotary valve is arranged on the liquid path outside the syringe and communicates with the syringe.

[0027] The first stepping motor is installed on the pump body support, and the output shaft of the first stepping motor is coaxially arranged with the rotating shaft of the rotary valve.

[0028] The coupling is columnar, one end of the coupling is fixedly connected with the output end of the first stepping motor, and the other end of the coupling is inserted into the driving end of the rotary valve; the coupling is made of flexible material.

[0029] As an optional technical solution, the pump body support comprises:

[0030] The support plate, the upper support and the lower support are vertically arranged at the upper end and the lower end of the support plate.

[0031] The technical scheme of the present application has the following advantages:

[0032] 1. The high-precision injection pump provided by the present application comprises a pump body support, a lead screw, a nut and an elastic member. The two ends of the lead screw are rotatably installed in the pump body support through a first bearing and a second bearing respectively, and the lead screw is connected with a second stepping motor. The nut is threadedly connected with the lead screw, and the nut is connected with the piston of a syringe. The elastic member is arranged between the first bearing and the pump body support or between the second bearing and the pump body support, one end of the elastic member abuts against the end face of the first bearing or the second bearing, and the other end of the elastic member abuts against the pump body support.

[0033] As we know, a bearing usually comprises a moving ring and a stationary ring, and a ball is arranged between the moving ring and the stationary ring. In the case of long service time or insufficient accuracy of the bearing itself, a gap may be generated between the moving ring and the ball, and between the stationary ring and the ball. The gap may also cause the lead screw to have the possibility of moving up and down along the axial direction, thereby causing the movement of the nut to be not completely synchronized with the second stepping motor when the lead screw drives the nut to move up and down reciprocatingly.

[0034] And in the high precision syringe pump provided by the application, the elastic member is arranged between the first bearing or the second bearing and the pump body support, and the elastic member presses the first bearing or the second bearing, so that when the first bearing or the second bearing has the above-mentioned condition of increased gap, the elastic member can push the first bearing or the second bearing to move in the direction of extruding the lead screw, thereby making up for the up-and-down movement of the lead screw caused by the bearing gap. Therefore, the high precision syringe pump provided by the application has higher delivery precision, and the delivery process is more stable and accurate.

[0035] 2. The high precision syringe pump provided by the application, wherein the upper end of the lead screw is installed on the pump body support through the first bearing, the elastic member is arranged between the first bearing and the pump body support, and the second stepper motor is installed in linkage with the lower end of the lead screw.

[0036] In the above structure, when the elastic member is arranged on the first bearing at the upper end of the lead screw, compared with the spring arranged at the lower end of the lead screw, the elastic member does not need to overcome the gravity of the lead screw in the process of pressing the first bearing, so that the elastic force can be fully utilized to increase the thrust on the bearing, force the first bearing and the second bearing to extrude the push rod more tightly, further reduce the possibility of up-and-down movement of the lead screw, and improve the accuracy of the whole high precision syringe pump.

[0037] 3. The high precision syringe pump provided by the application, further comprising two guide rods, one end of another guide rod is fixedly connected with the pump body support, the other end is inserted into the insertion hole in the pump body support, and there is a gap between the other end and the bottom wall of the insertion hole.

[0038] In general, we think that the two guide rods are designed in the form of fixed installation at both ends, which has a more stable structure, and thus has a better guiding effect on the movement of the sliding block, making the movement of the sliding block more stable. However, through repeated tests by the inventor under high precision conditions, it is concluded that the design of one end of one of the guide rods in the form of suspension in the above structure is even better for the stability of the sliding block. The reason is that under high precision conditions, the existing machining precision is difficult to meet the precision requirements of the high precision syringe pump. Whether in the process of assembly or machining, it is possible to cause the positional error of the two guide rods, and when the parallelism of the two guide rods has an error, it is difficult to ensure that the movement of the sliding block meets the needs under high precision conditions. At this time, the movement of the sliding block is prone to a short-term seizure phenomenon between the two guide rods, thereby affecting the stability of the movement of the sliding block.

[0039] Therefore, in the above structure, one end of one of the guide rods is designed in the form of suspension, and the other end is designed in the form of fixed structure. When the sliding block has a seizure tendency, the guide rod has an axial displacement gap, which can effectively adapt to the movement of the sliding block in the guiding process, while ensuring that the lead screw lead accuracy is fully utilized.

[0040] 4. The high-precision injection pump provided by the application has the following advantages: the material of the screw nut is engineering plastic; the screw nut made of engineering plastic can be radially contracted, so that the screw nut and the screw rod are always in close contact, the transmission precision is kept accurate, and the constant output speed is ensured.

[0041] 5. The high-precision injection pump provided by the application further comprises a rotary valve, a first stepping motor and a coupling. The rotary valve is installed on the pump body support, and is arranged on the liquid path outside the syringe and communicates with the syringe. The first stepping motor is installed on the pump body support, and the output shaft of the first stepping motor is coaxially arranged with the rotating shaft of the rotary valve. The coupling is columnar, one end of the coupling is fixedly connected with the output end of the first stepping motor, and the other end of the coupling is inserted into the driving end of the rotary valve. The coupling is made of flexible material.

[0042] In the prior art, in order to ensure the assembly precision, the rotary valve of the high-precision injection pump is usually made of soft material. In this case, if the rotary valve is directly connected to the output shaft of the stepping motor, a large impact will be applied to the rotary valve, and the rotary valve will be worn out after a long time. In the high-precision injection pump provided by the application, the coupling is designed, and the coupling is made of flexible material. When the torque on the first stepping motor is transmitted to the driving end of the rotary valve, the coupling itself can buffer the torque to a certain extent, thereby reducing the impact of the first stepping motor on the coupling and prolonging the service life of the rotary valve and the entire high-precision injection pump. At the same time, the coupling is designed in a columnar shape, and the coupling is easier to twist in the length direction, thereby further improving the buffering capacity of the coupling to the torque.

[0043] In summary, compared with the injection pump in the prior art, the high-precision injection pump provided by the application effectively solves the problem of the screw rod shifting and affecting the conveying precision, and has the advantages of good self-adaptive guiding capability, long service life and the like. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0045] Figure 1 FIG. 1 is a sectional view of the high-precision injection pump of the application.

[0046] Figure 2 FIG. 2 is a first angle perspective view of the high-precision injection pump of the application.

[0047] Figure 3 Fig. 2 is a second perspective view of the high-precision injection pump of the present application.

[0048] Figure 4 Fig. 4 is a schematic view of the cooperation structure of the lead screw and the guide rod of the present application.

[0049] Figure 5 Fig. 6 is a schematic view of the mounting structure of the elastic member of the present application.

[0050] Figure 6 Fig. 8 is a schematic view of the mounting structure of the rotary valve of the present application.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] 1, support plate; 2, upper support; 3, lower support; 4, rotary valve; 5, first stepper motor; 6, syringe; 7, lead screw; 8, lead nut; 9, sliding block; 10, elastic member; 11, first bearing; 12, push rod; 13, connecting shaft; 14, guide rod; 15, guide sleeve; 16, coupling; 17, second stepper motor; 18, spring pressing plate; 19, first pulley; 20, second pulley; 21, transmission belt; 22, second bearing. DETAILED DESCRIPTION

[0053] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0054] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0055] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0057] The embodiment provides a high-precision injection pump, which comprises a pump body support, a rotary valve 4, a lead screw 7, a lead screw nut 8 and an elastic member 10. Figures 1-3 As shown in the figure, the high-precision injection pump comprises a pump body support, a rotary valve 4, a lead screw 7, a lead screw nut 8 and an elastic member 10.

[0058] The pump body support is provided with a support plate 1 arranged vertically, an upper support 2 is vertically arranged at the upper end of the support plate 1, and a lower support 3 is vertically arranged at the lower end of the support plate 1. The rotary valve 4 is arranged on the support plate 1, the rotary valve 4 is connected with a first stepping motor 5, and the rotary valve 4 is connected with the cavity of a syringe 6. The rotary valve 4 is driven to move by the first stepping motor 5, and the liquid path direction of the fluid is switched.

[0059] Referring to Figure 6 , the rotary valve 4, the first stepping motor 5 and the shaft coupling 16 are installed on the pump body support, the rotary valve 4 is arranged on the liquid path outside the syringe 6 and communicates with the syringe 6; the first stepping motor 5 is installed on the pump body support, the output shaft of the first stepping motor 5 is coaxially arranged with the rotating shaft of the rotary valve 4; the shaft coupling 16 is columnar, one end of the shaft coupling 16 is fixedly connected with the output end of the first stepping motor 5, and the other end of the shaft coupling 16 is inserted into the driving end of the rotary valve 4; the shaft coupling 16 is made of flexible material.

[0060] In the prior art, in order to ensure assembly precision, the rotary valve on the high-precision injection pump is usually made of soft material, in this case, if the rotary valve is directly connected to the output shaft of the stepping motor, a large impact will be applied to the rotary valve, and the rotary valve will be worn out after a long time. In the high-precision injection pump provided in the application, the shaft coupling 16 is designed, and the shaft coupling 16 is made of flexible material, at this time, when the torque on the first stepping motor 5 is transmitted to the driving end of the rotary valve 4, the shaft coupling 16 itself can buffer the torque to a certain extent, thereby reducing the impact of the first stepping motor 5 on the shaft coupling 16, and the service life of the rotary valve 4 itself and the whole high-precision injection pump is improved. At the same time, the shaft coupling 16 is designed in a columnar shape, and it is easier to twist in the length direction, and the buffering capacity of the shaft coupling 16 for the torque is further improved.

[0061] Referring to Figure 4 , the lead screw 7 is connected with the lower support 3 through the second bearing 22, and the second stepping motor 17 and the lead screw 7 are connected through a belt drive, that is, the driving end of the second stepping motor 17 is connected with the second pulley 20, the lower end of the lead screw 7 is connected with the first pulley 19, and the first pulley 19 and the second pulley 20 are connected through the transmission belt 21.

[0062] A screw rod 7 is rotatably connected between the upper support 2 and the lower support 3, and the screw rod 7 is connected with the second stepping motor 17 through a transmission mechanism. A screw nut 8 is threadedly connected on the screw rod 7, and the screw nut 8 is connected with the piston of the syringe 6. In use, the second stepping motor 17 drives the screw rod 7 to rotate, and the screw rod 7 drives the screw nut 8 to move up and down, and further drives the piston of the syringe 6 to move up and down. The liquid path is formed by the cooperation of the syringe 6 and the rotary valve 4, and the fluid is quantitatively output.

[0063] An elastic member 10 is arranged between the upper end of the screw rod 7 and the upper support 2. The elastic member 10 can eliminate the axial gap in the long-term use process, and ensure the precision of the transmission of the screw rod 7, and greatly improve the stability and sensitivity of the liquid transmission.

[0064] As shown in Figure 1 , 5 , the screw rod 7 is connected with the upper support 2 through the first bearing 11, and the elastic member 10 is arranged between the first bearing 11 and the upper support 2. Specifically, the elastic member 10 presses the first bearing 11, and the elastic member 10 is pressed in the upper support 2 through the spring pressing plate 18, so as to realize the axial gap elimination of the screw rod 7.

[0065] As shown in Figure 2 , the outer side of the screw nut 8 is connected with a sliding block 9, and one end of a push rod 12 is connected with the sliding block 9. A strip-shaped through hole is formed on the support plate 1 along the axial direction of the screw rod 7, and the other end of the push rod 12 passes through the strip-shaped through hole and is connected with the piston of the syringe 6 through a connecting shaft 13.

[0066] Two sliding holes are formed on the sliding block 9, and a guide rod 14 is slidably arranged in each sliding hole. The two guide rods 14 are parallel to the two sides of the screw rod 7, so as to ensure that the two guide rods 14 and the screw rod 7 are located in the same plane. One end of one guide rod 14 is fixedly connected with the upper support 2 and the lower support 3, and the other end of the other guide rod 14 is fixedly connected with the upper support 2 and the lower support 3. The floating setting process is inserted into the lower support 3, but the floating is not fixed, mainly to ensure the parallelism of the vertical movement guide in the assembly process. Because the single-axis guide has the tendency of torque torsion, the double-axis parallel assembly, and the screw rod 7 transmission and the two guide rods 14 are located in the same plane, the driving force generates the guide force at the same time without the transmission lock phenomenon. The double-axis setting with one end fixed and the other end floating can obviously eliminate this risk.

[0067] As shown in Figure 3 , 4As shown, a guide sleeve 15 is arranged in the sliding hole, the guide rod 14 slides through the guide sleeve 15, and the material of the guide sleeve 15 is engineering plastic. The guide sleeve 15 is arranged to facilitate the axial movement of the two guide rods 14, and realizes the self-lubricating movement of the guide rod 14. The linear guide sleeve 15 is in transition fit with the sliding block 9, and the linear guide sleeve 15 is in clearance fit with the guide rod 14. The two guide rods 14 move vertically up and down in the two linear guide sleeves 15.

[0068] Further, the material of the nut 8 is engineering plastic. The nut 8 made of engineering plastic can be radially contracted, so that the nut 8 and the screw rod 7 are always in close fit, realizing real-time dynamic clearance elimination during the movement of the screw rod 7, so as to maintain accurate transmission accuracy and ensure constant output speed.

[0069] Further, a coupling 16 is arranged between the rotary valve 4 and the first stepping motor 5, and the material of the coupling 16 is engineering plastic. The coupling 16 is in the form of a floating coupling 16, that is, the part connected with the first stepping motor 5 is fastened, and the other part is floating cantilever. In use, the output end of the rotary valve 4 is inserted into the coupling 16, realizing the protection of the rotary valve 4 during transmission.

[0070] In summary, in the present scheme, the axial clearance of the screw rod 7 is eliminated by arranging the elastic member 10 axially, and the real-time dynamic clearance elimination during the movement of the screw rod 7 is realized by arranging the nut 8 to be flexible, which improves the transmission accuracy as a whole. The linear guide sleeve 15 is embedded in the guide rod 14 during the guide movement, realizing self-lubricating maintenance. One guide rod 14 is fixedly arranged, and the other end of the other guide rod 14 is fixed and the other end is floating, which fully guarantees the parallelism of the vertical movement guide, increases the service life, and improves the reliability of use.

[0071] Obviously, the above embodiments are only examples for clear illustration, and are not limitations on the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A high precision syringe pump characterized by, Comprise: Pump body support; Screw rod (7), both ends of the screw rod (7) are rotatably installed in the pump body support through the first bearing (11) and the second bearing (22) respectively, the screw rod (7) is installed in linkage with the second stepper motor (17); Screw nut (8), threaded connection with the screw rod (7), the screw nut (8) is connected with the piston of the syringe (6); Elastic member (10), arranged between the first bearing (11) and the pump body support or between the second bearing (22) and the pump body support, one end of the elastic member (10) abuts on the end face of the first bearing (11) or the second bearing (22), the other end abuts on the pump body support; The upper end of the screw rod (7) is installed on the pump body support through the first bearing (11), the elastic member (10) is arranged between the first bearing (11) and the pump body support, and the second stepper motor (17) is installed in linkage with the lower end of the screw rod; Also comprising: Slide block (9), fixedly installed with the screw nut (8), the push rod (12) is connected to the slide block (9); one end of the push rod (12) extends out of the pump body support through the strip-shaped through hole formed in the pump body support and is connected with the piston of the syringe (6); Also comprising: Guide rod (14), having two; the guide rod (14) is fixedly connected with the pump body support; the guide rod is arranged in parallel with the screw rod (7); the slide block (9) is slidably installed on the guide rod (14); One end of one of the two guide rods (14) is fixedly connected and installed in the pump body support; The other end of the other guide rod (14) of the two guide rods (14) is fixedly connected with the pump body support, the other end is inserted into the insertion hole in the pump body support, and there is a gap between the other end and the bottom wall of the insertion hole.

2. The high precision syringe pump of claim 1, wherein, Also comprising: Guide sleeve (15), fixedly installed on the slide block (9); the guide rod (14) passes through the guide sleeve (15) and slidably cooperates with the guide sleeve (15).

3. The high precision syringe pump of claim 1, wherein, The two guide rods (14) are located in the same plane as the screw rod (7), and the two guide rods (14) are symmetrically arranged on both sides of the screw rod (7).

4. The high precision syringe pump of any one of claims 1-3, wherein, The material of the screw nut (8) is engineering plastic.

5. The high precision syringe pump of claim 1, wherein, Also comprising: Rotary valve (4), installed on the pump body support, the rotary valve (4) is arranged on the liquid path outside the syringe (6) and communicates with the syringe (6); First stepper motor (5), installed on the pump body support, the output shaft of the first stepper motor (5) is coaxially arranged with the rotating shaft of the rotary valve (4); Coupling (16), columnar, one end of the coupling (16) is fixedly connected with the output end of the first stepper motor (5), the other end is inserted into the driving end of the rotary valve (4); the coupling (16) is made of flexible material.

6. The high precision syringe pump of claim 1, wherein, The pump body support comprises: Support plate (1), upper support (2) and lower support (3), the upper support (2) is vertically arranged at the upper end of the support plate (1), and the lower support (3) is vertically arranged at the lower end of the support plate (1).

Images