Multifunctional automatic sample injector

Abstract

The invention relates to the technical field of liquid chromatography, in particular to a multifunctional automatic sampler. Comprising a pump, a three-way piece, a sample injection valve, a chromatographic column, a detector, a sample injection assembly and a sample introduction device, the pump is communicated with the three-way piece, the three-way piece, the chromatographic column, the sample injection assembly and the sample introduction device are connected to the sample injection valve, and the end, away from the sample injection valve, of the chromatographic column is communicated with the detector; a first quantitative loop and a second quantitative loop are connected in the sample injection valve; switching the sample injection valve, and controlling two ends of the first quantitative loop to be communicated with the sample injection assembly and the sample introduction device respectively or communicated with the pump and the chromatographic column respectively; when the two ends of the first quantitative loop are communicated with the sample introduction assembly and the sample introduction device, the two ends of the second quantitative loop are respectively communicated with the pump and the chromatographic column; when the two ends of the first quantitative loop are respectively communicated with the pump and the chromatographic column, the two ends of the second quantitative loop are communicated with the sample introduction assembly and the sample introduction device; the cost is reduced, the sample injection is rapid, and the use error-tolerant rate of the high performance liquid chromatograph is improved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid chromatography, in particular to a multifunctional automatic sample injector. Background Art

[0002] As one of the important modules of liquid chromatography, the injection accuracy, injection repeatability and sample residue of the autosampler are certainly important parameter indicators. However, with the widening of the application scope of HPLC, more sample detection volume has prompted faster injection speed to become the next trend in the development of instruments. At the same time, with the rapid development of the analytical instrument industry and the increasingly accelerated pace of work, higher sample analysis efficiency has also become an important indicator for users to evaluate instruments. Therefore, a higher fault tolerance rate of the instrument has become a new goal pursued by practitioners in related industries.

[0003] For the solution of fast injection, some instrument manufacturers focus on improving the completion speed of each step in the injection process, such as increasing the moving speed of the injection needle, speeding up the injection needle cleaning process, etc. Although this method can improve the injection speed to a certain extent, too fast movement may reduce the service life of various instrument accessories; some instrument manufacturers use dual injection valves and dual injection needles to achieve fast injection by switching flow paths. The main disadvantage is that the dual injection valve-dual injection needle instrument is more expensive, and compared with the single injection valve-single injection needle, it increases the potential failure points of the instrument.

[0004] At the same time, as for the fault tolerance of high-performance liquid chromatography, more samples need to be tested and more experimental operators are competing for their posts. The probability of many newcomers making mistakes in the process of testing many samples will increase significantly. Therefore, a higher instrument fault tolerance will greatly reduce system abnormalities caused by human error, thereby greatly improving the efficiency of analysis and detection. For this, some instrument manufacturers have added many prompt functions to the workstation, such as the amount of mobile phase, the minimum sample amount estimation, etc.; some instrument manufacturers have reduced and simplified the instrument operation steps to reduce the efficiency reduction caused by the operator's difficulty in using the instrument and lack of proficiency in use. As for the automatic sampler, the most common problem is that the target sample bottle is placed in the wrong position due to operator negligence, which will result in no sample at the target position during injection, causing some bubbles to enter the liquid chromatography system, thereby affecting the analysis results of subsequent samples; the sample tray specifications may also be used incorrectly, resulting in the injection needle mistakenly piercing the edge of the sample tray during the injection process, which will cause irreversible damage to the injection needle, such as bending and clogging, which will ultimately lead to a reduction in the efficiency of sample analysis and detection.

[0005] Therefore, there is an urgent need to provide a multifunctional automatic sample injector, which, compared with the existing technology, can reduce costs, speed up sample injection, and improve the error tolerance of high performance liquid chromatograph use. Summary of the invention

[0006] The invention solves the technical problems existing in the prior art and provides a multifunctional automatic sample injector.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A multifunctional automatic sampler, comprising a pump, a three-way piece, an injection valve, a chromatographic column, a detector, an injection assembly and a sample introduction device, wherein the pump is connected to the three-way piece, the injection valve is respectively connected to the three-way piece, the chromatographic column, the injection assembly and the sample introduction device, and one end of the chromatographic column away from the injection valve is connected to the detector; the injection valve is internally connected to a first quantitative ring and a second quantitative ring;

[0009] Switch the injection valve to control the two ends of the first quantitative loop to be connected to the injection assembly and the sample introduction device respectively or to be connected to the pump and the chromatographic column respectively; when the two ends of the first quantitative loop are connected to the injection assembly and the sample introduction device, the two ends of the second quantitative loop are connected to the pump and the chromatographic column respectively; when the two ends of the first quantitative loop are connected to the pump and the chromatographic column respectively, the two ends of the second quantitative loop are connected to the injection assembly and the sample introduction device.

[0010] Further, the injection valve is a two-position ten-way injection valve, which includes a first interface, a second interface, a third interface, a fourth interface, a fifth interface, a sixth interface, a seventh interface, an eighth interface, a ninth interface and a tenth interface, the first quantitative loop is connected between the third interface and the ninth interface, the second quantitative loop is connected between the first interface and the fifth interface, the second interface is connected to the chromatographic column, the fourth interface is connected to the injection assembly, the sixth interface and the eighth interface are both connected to the three-way piece, the tenth interface is connected to the sample introduction device, and the seventh interface is blocked with a plug.

[0011] Furthermore, the three-way piece is provided with a first connection port, a second connection port and a third connection port, the first connection port is communicated with the pump, the second connection port is communicated with the eighth port, and the third connection port is communicated with the sixth port.

[0012] Furthermore, the pipe connecting the second connection port and the eighth interface and the pipe connecting the third connection port and the sixth interface are of the same length.

[0013] Furthermore, the detector is connected to a waste liquid box at one end away from the chromatographic column.

[0014] Furthermore, the injection assembly includes a motor, a fixed frame, an L-shaped plate, a threaded rod, a slider and an injection needle, the motor and the L-shaped plate are fixedly connected to the fixed frame, the threaded rod is rotatably connected between the L-shaped plate and the fixed frame, the motor drives the threaded rod to rotate, the slider is threadedly connected to the threaded rod, and when the threaded rod rotates, the slider moves along the vertical direction of the threaded rod, and the injection needle is connected to the slider.

[0015] Furthermore, the slider is fixedly connected to a clamping block, the injection needle is connected to the clamping block, a detection rod is passed through the clamping block, the upper end of the detection rod passes through the clamping block and is connected to a baffle, and a spring is fixedly connected between the baffle and the clamping block.

[0016] Furthermore, the lower end of the detection rod is fixedly connected to a baffle plate, the baffle plate is provided with a through hole, and the injection needle is inserted into the through hole.

[0017] Furthermore, the upper wall of the clamping block is fixedly connected to a U-shaped plate, an indicator light is set on the side wall of the U-shaped plate, an optocoupler switch is provided inside the U-shaped plate, the optocoupler switch is connected in series to the conduction circuit of the indicator light, and the baffle is used to cover the optocoupler switch to control whether the optocoupler switch is turned on, and the indicator light is electrically connected to the controller.

[0018] Furthermore, the controller is electrically connected to the motor, and the controller receives the current signal of the motor. The controller is provided with a maximum operating current value. When the motor is rotating, if the current value received by the controller is always less than or equal to the maximum operating current value, it indicates that the injection needle has not been mis-pierced. If the current value received by the controller is greater than the maximum operating current value, it indicates that the injection needle has been mis-pierced.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention can complete rapid injection using a single injection valve and a single injection needle. Compared with the traditional double injection valve and double injection needle, it not only saves costs, but also achieves rapid injection, improves the processing rate of the injector, and has fewer potential failure points.

[0021] (2) The present invention only needs to switch the injection valve once each time the injection-analysis function is implemented. Compared with the conventional injection method, which requires switching the injection valve at least twice, the service life of the injection valve is increased, or even doubled.

[0022] (3) In the present invention, two quantitative loops are arranged in the same injection valve. When one of the quantitative loops is analyzing, the other quantitative loop is performing the injection operation. After the analysis is completed, the injection valve is switched once, and the quantitative loop that has completed the injection can be switched to the analysis mode, and the quantitative loop that has completed the analysis can be switched to the injection mode at the same time, thereby achieving simultaneous injection and analysis, and improving the analysis and detection efficiency.

[0023] (4) The present invention also has the functions of detecting an empty bottle at the target sample bottle position and alarming for mispuncture of the injection needle, which effectively improves the fault tolerance of the high performance liquid chromatograph and effectively reduces system abnormalities caused by human negligence or misoperation, thereby greatly improving the analysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram showing the first quantitative loop injection and the second quantitative loop analysis of the present invention.

[0025] Figure 2 It is a schematic diagram showing the first quantitative loop analysis and the second quantitative loop injection of the present invention.

[0026] Figure 3 Schematic diagram of the sample injection assembly of the present invention.

[0027] Description of reference numerals:

[0028] 1. Pump; 101. Outlet; 2. Tee; 21. First connection port; 22. Second connection port; 23. Third connection port; 3. Injection valve; 31. First interface; 32. Second interface; 33. Third interface; 34. Fourth interface; 35. Fifth interface; 36. Sixth interface; 37. Seventh interface; 38. Eighth interface; 39. Ninth interface; 310. Tenth interface; 4. First quantitative loop; 5. Second quantitative loop; 6. Chromatographic column; 61. Inlet mouth; 62, liquid outlet; 7, detector; 71, detection inlet; 72, detection outlet; 8, waste liquid box; 9, injection assembly; 91, motor; 92, timing belt; 93, indicator light; 94, injection needle; 95, detection rod; 96, spring; 97, baffle; 98, fixing bracket; 99, L-shaped plate; 910, threaded rod; 911, slider; 912, clamping block; 913, baffle; 914, U-shaped plate; 10, sample introduction device; 11, sample bottle. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. It should be noted that the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] like Figure 1 As shown, the present invention provides a multifunctional automatic sampler, including a pump 1, a three-way piece 2, an injection valve 3, a first quantitative loop 4, a second quantitative loop 5, a chromatographic column 6, a detector 7, a waste liquid box 8, an injection component 9, a sample introduction device 10 and a sample bottle 11. The pump 1 is connected to the three-way piece 2, the three-way piece 2 is connected to the injection valve 3, the injection valve 3 is also connected to the chromatographic column 6, the injection component 9 and the sample introduction device 10 respectively, the chromatographic column 6 is connected to the detector 7, the detector 7 is connected to the waste liquid box 8, and the sample bottle 11 is arranged corresponding to the injection component 9.

[0031] The pump 1 is provided with an outlet 101, the tee piece 2 is provided with a first connection port 21, a second connection port 22 and a third connection port 23, the outlet 101 of the pump 1 is connected with the first connection port 21 through a pipeline, the injection valve 3 is a two-position ten-way injection valve, the injection valve 3 is provided with a first interface 31, a second interface 32, a third interface 33, a fourth interface 34, a fifth interface 35, a sixth interface 36, a seventh interface 37, an eighth interface 38, a ninth interface 39 and a tenth interface 310, the second connection port 22 of the tee piece 2 is connected with the eighth interface 38 through a pipeline, the third connection port 23 of the tee piece 2 is connected with the sixth interface 36 through a pipeline, the third interface 33 and The ninth interface 39 is connected through the first quantitative ring 4, and the first interface 31 and the fifth interface 35 are connected through the second quantitative ring 5; the chromatographic column 6 is provided with a liquid inlet 61 and a liquid outlet 62, the liquid inlet 61 of the chromatographic column 6 is connected to the second interface 32 through a pipeline, the detector 7 is provided with a detection inlet 71 and a detection outlet 72, the liquid outlet 62 of the chromatographic column is connected to the detection inlet 71 of the detector 7 through a pipeline, and the detection outlet 72 of the detector 7 is connected to the waste liquid box 8 through a pipeline; the tenth interface 310 is connected to the sample introduction device 10 through a pipeline, and the fourth interface 34 is connected to the injection assembly 9 through a pipeline; the seventh interface 37 is blocked with a plug.

[0032] The pipeline connecting the second connection port 22 of the tee 2 and the eighth interface 38 and the pipeline connecting the third connection port 23 of the tee 2 and the sixth interface 36 are configured to be pipelines of the same length.

[0033] Injection valve 3 Figure 1 When the connection relationship is shown, that is, the first interface 31 is connected to the second interface 32, the third interface 33 is connected to the fourth interface 34, the fifth interface 35 is connected to the sixth interface 36, the seventh interface 37 is connected to the eighth interface 38, and the ninth interface 39 is connected to the tenth interface 310, one end of the first quantitative loop 4 is connected to the sample introduction device 10, the other end of the first quantitative loop 4 is connected to the injection assembly 9, one end of the second quantitative loop 5 is connected to the outlet 101 of the pump 1, and the other end of the second quantitative loop 5 is connected to the liquid inlet 61 of the chromatographic column 6. At this time, the first quantitative loop 4 is in the injection state and the second quantitative loop 5 is in the analysis state; wait Figure 1 After the status analysis is completed, the injection valve 3 is controlled to switch to Figure 2 In the state shown, that is, the first interface 31 is connected to the tenth interface 310, the second interface 32 is connected to the third interface 33, the fourth interface 34 is connected to the fifth interface 35, the sixth interface 36 is connected to the seventh interface 37, and the eighth interface 38 is connected to the ninth interface 39. At this time, one end of the first quantitative loop 4 is connected to the outlet 101 of the pump 1, and the other end of the first quantitative loop 4 is connected to the liquid inlet 61 of the chromatographic column 6, one end of the second quantitative loop 5 is connected to the injection assembly 9, and the other end of the second quantitative loop 5 is connected to the sample introduction device 10. At this time, the first quantitative loop 4 is in the state of being divided. The first quantitative ring 4 and the second quantitative ring 5 are in the analysis state and the second quantitative ring 5 is in the injection state; the injection valve 3 is controlled to switch once, so that the first quantitative ring 4 and the second quantitative ring 5 can be switched between the injection and analysis states, so that the first quantitative ring 4, which was in the injection state in the previous state, enters the analysis state after switching, and then the second quantitative ring 5 is switched to the injection state. Each time the switch is made, there is a quantitative ring that has completed the injection, which can realize fast injection. While one of the quantitative rings is analyzing, the other quantitative ring is in the injection state, which saves the injection time and thus improves the working efficiency of the injector.

[0034] like Figure 3As shown, the injection assembly 9 includes a fixing frame 98, a motor 91, a synchronous belt 92, an indicator light 93, an injection needle 94, a detection rod 95, a spring 96 and a baffle 97. The motor 91 is fixedly connected to the lower wall of the fixing frame 98. The lower wall of the fixing frame 98 is fixedly connected to an L-shaped plate 99. The L-shaped plate 99 includes a short portion and a long portion that are integrally connected. The short portion is arranged parallel to the fixing frame 98, and one end of the long portion away from the short portion is fixedly connected to the lower wall of the fixing frame 98. The fixing frame 98 is penetrated by a threaded rod 910, and the threaded rod 910 is rotatably connected to the fixing frame 98. The upper end of the threaded rod 910 extends The fixing frame 98 is extended outward, the lower end of the threaded rod 910 is rotatably connected to the short part, a slider 911 is sleeved on the outside of the threaded rod 910, the slider 911 is threadedly connected to the threaded rod 910, the slider 911 slides between the fixing frame 98 and the short part, and a limit rod (not shown in the figure) is also penetrated on the slider 911, the upper end of the limit rod is fixedly connected to the fixing frame 98, and the lower end of the limit rod is fixedly connected to the short part. The limit rod is set to ensure that the slider 911 can slide in the vertical direction during the rotation of the threaded rod 910; the side wall of the slider 911 is fixedly connected to the clamping block 912, and the clamping block 912 is penetrated by an inlet The sample needle 94 is provided with a detection rod 95 on the clamping block 912, the upper end of the detection rod 95 is fixedly connected to a baffle 97, the baffle 97 is in the shape of a "few", the detection rod 95 is slidably connected relative to the clamping block 912, the baffle 97 extends out of the upper wall of the clamping block 912, the lower wall of the baffle 97 is fixedly connected to a spring 96, the lower wall of the spring 96 is fixedly connected to the upper wall of the clamping block 912, the upper wall of the clamping block 912 is fixedly connected to a U-shaped plate 914, the side wall of the U-shaped plate 914 is fixedly connected to an indicator light 93, an optical coupler switch is provided on the inner wall of the U-shaped plate 914, and the optical coupler switch is connected in series to the conduction circuit of the indicator light 93 On the way, the vertical part of the right side of the baffle 97 is deeply set inside the U-shaped plate 914, and the indicator light 93 is connected to the controller; the lower end of the detection rod 95 is integrally connected to the baffle 913, and the baffle 913 is provided with a perforation, and the injection needle 94 is set corresponding to the perforation, and the injection needle 94 extends into the perforation; the sample bottle 11 is located below the injection component 9, and the bottle mouth of the sample bottle 11 is set corresponding to the injection needle 94; the synchronous belt 92 is sleeved on the output end of the motor 91 and the upper end of the threaded rod 910 extending out of the fixed frame 98. When the motor 91 is started, the threaded rod 910 can be driven to rotate under the action of the synchronous belt 92.

[0035] When the slider 911 is located at the uppermost position of the L-shaped plate 99, it is the initial state of the injection needle 94. When the injection needle 94 is in the initial state, the lower end of the injection needle 94 is located inside the perforation of the baffle 913, and the lower end of the injection needle 94 is flush with the lower end of the baffle 913; when the injection needle 94 is in the initial state, the distance between the lower end of the baffle 913 and the bottle mouth of the sample bottle 11 is a first set distance, and the driving motor 91 rotates to move the slider 911 downward by a second set distance, which is slightly larger than the first set distance. When the baffle 913 contacts the bottle mouth of the sample bottle 11, the detection rod 95 will stop The slider 911 continues to move downward, so that the clamping block 912 moves downward relative to the baffle 97, so that the spring 96 is stretched, so that the vertical portion on the right side of the baffle 97 slides out from the inside of the U-shaped plate, so that it cannot block the optical coupling switch. The optical coupling switch receives light and turns on, so that the indicator light 93 lights up, indicating that there is a sample bottle 11 below. If there is no sample bottle below, the baffle 813 will continue to move with the slider 911, and the baffle 97 always blocks the optical coupling switch, and the indicator light 93 is in an off state. Whether the indicator light 93 is on can be used to determine whether a sample bottle 11 is placed correspondingly below the injection assembly 9.

[0036] The controller is electrically connected to the motor 91, and the controller receives the current signal of the motor 91. The controller is provided with a maximum operating current value. When the motor 91 is rotating, if the current value of the motor 91 received by the controller is always less than or equal to the maximum operating current value, it proves that the injection needle 94 has not been mis-pierced. When the current value of the motor 91 received by the controller is greater than the maximum operating current value, it indicates that the injection needle 94 has been mis-pierced.

[0037] The present invention can complete rapid injection using a single injection valve 3-single injection needle 94. Compared with the traditional double injection valve 3-double injection needle 94, it not only saves costs, but also realizes rapid injection, improves the processing rate of the injector, and has fewer potential failure points; each time the injection-analysis function is realized, the injection valve 3 only needs to be switched once, compared with the conventional injection method that requires switching the injection valve 3 at least twice, so that the service life of the injection valve 3 is increased, or even doubled; two quantitative loops are arranged in the same injection valve 3, when one of the quantitative loops is analyzing, the other quantitative loop is performing the injection operation, and after the analysis is completed, the injection valve 3 is switched once, and the quantitative loop that has completed the injection can be converted to the analysis mode, and the quantitative loop that has completed the analysis is simultaneously converted to the injection mode, thereby realizing the simultaneous execution of injection and analysis, and improving the analysis and detection efficiency.

[0038] The present invention also has the functions of empty bottle detection at the position of the target sample bottle 11 and mis-puncture alarm of the injection needle 94, which effectively improves the fault tolerance of the high performance liquid chromatograph and effectively reduces system abnormalities caused by human negligence or misoperation, thereby greatly improving the analysis efficiency.

[0039] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A multifunctional automatic sample injector, characterized in that: The invention comprises a pump, a three-way piece, an injection valve, a chromatographic column, a detector, an injection assembly and a sample introduction device, wherein the pump is connected to the three-way piece, the injection valve is respectively connected to the three-way piece, the chromatographic column, the injection assembly and the sample introduction device, and one end of the chromatographic column away from the injection valve is connected to the detector; the injection valve is internally connected to a first quantitative ring and a second quantitative ring; Switch the injection valve to control the two ends of the first quantitative loop to be connected to the injection assembly and the sample introduction device respectively or to be connected to the pump and the chromatographic column respectively; when the two ends of the first quantitative loop are connected to the injection assembly and the sample introduction device, the two ends of the second quantitative loop are connected to the pump and the chromatographic column respectively; when the two ends of the first quantitative loop are connected to the pump and the chromatographic column respectively, the two ends of the second quantitative loop are connected to the injection assembly and the sample introduction device.

2. A multifunctional automatic sample injector according to claim 1, characterized in that: The injection valve is a two-position ten-way injection valve, which includes a first interface, a second interface, a third interface, a fourth interface, a fifth interface, a sixth interface, a seventh interface, an eighth interface, a ninth interface and a tenth interface, the first quantitative loop is connected between the third interface and the ninth interface, the second quantitative loop is connected between the first interface and the fifth interface, the second interface is connected to the chromatographic column, the fourth interface is connected to the injection assembly, the sixth interface and the eighth interface are both connected to the three-way piece, the tenth interface is connected to the sample introduction device, and the seventh interface is blocked with a plug.

3. A multifunctional automatic sample injector according to claim 2, characterized in that: The three-way piece is provided with a first connection port, a second connection port and a third connection port, the first connection port is communicated with the pump, the second connection port is communicated with the eighth port, and the third connection port is communicated with the sixth port.

4. A multifunctional automatic sample injector according to claim 3, characterized in that: The pipe connecting the second connection port and the eighth interface and the pipe connecting the third connection port and the sixth interface are of the same length.

5. A multifunctional automatic sample injector according to claim 1, characterized in that: The detector is connected to a waste liquid box at one end away from the chromatographic column.

6. A multifunctional automatic sample injector according to claim 1, characterized in that: The injection assembly includes a motor, a fixed frame, an L-shaped plate, a threaded rod, a slider and an injection needle. The motor and the L-shaped plate are fixedly connected to the fixed frame. The threaded rod is rotatably connected between the L-shaped plate and the fixed frame. The motor drives the threaded rod to rotate. The slider is threadedly connected to the threaded rod. When the threaded rod rotates, the slider moves along the vertical direction of the threaded rod. The injection needle is connected to the slider.

7. A multifunctional automatic sample injector according to claim 6, characterized in that: The slider is fixedly connected to a clamping block, the injection needle is connected to the clamping block, a detection rod is passed through the clamping block, the upper end of the detection rod passes through the clamping block and is connected to a baffle, and a spring is fixedly connected between the baffle and the clamping block.

8. A multifunctional automatic sample injector according to claim 7, characterized in that: The lower end of the detection rod is fixedly connected to a baffle plate, a through hole is arranged on the baffle plate, and the injection needle is inserted into the through hole.

9. A multifunctional automatic sample injector according to claim 8, characterized in that: The upper wall of the clamping block is fixedly connected to the U-shaped plate, an indicator light is set on the side wall of the U-shaped plate, an optocoupler switch is provided inside the U-shaped plate, the optocoupler switch is connected in series to the conduction circuit of the indicator light, the baffle is used to cover the optocoupler switch, so as to control whether the optocoupler switch is turned on, and the indicator light is electrically connected to the controller.

10. The multifunctional automatic sample injector according to claim 8, characterized in that: The controller is electrically connected to the motor, and receives the current signal of the motor. The controller is provided with a maximum operating current value. When the motor is rotating, if the current value received by the controller is always less than or equal to the maximum operating current value, it indicates that the injection needle has not been mis-pierced. If the current value received by the controller is greater than the maximum operating current value, it indicates that the injection needle has been mis-pierced.

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