CN110404141B

CN110404141B - Full-automatic micro-injection device

Info

Publication number: CN110404141B
Application number: CN201910705144.XA
Authority: CN
Inventors: 田忠秋
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-08-01
Filing date: 2019-08-01
Publication date: 2021-07-30
Anticipated expiration: 2039-08-01
Also published as: CN110404141A

Abstract

A full-automatic microinjection device, the needle head replacing mechanism is equipped with n injection needles in a manner of being centrosymmetric with the sun axis; the needle changing mechanism is switched between a first movement state in the lower position and a second movement state in the upper position, the first movement state being: the needle head replacing mechanism rotates to replace the included angle alpha; the second motion state: the needle head replacing mechanism idles; the micro-injection mechanism is simultaneously in driving connection with the injector and the needle head replacement mechanism, and in the upper position, the micro-injection mechanism can drive the injection piston to move downwards from the upper limit position to the lower limit position and simultaneously drive the needle head replacement mechanism to complete a second motion state; in the lower position, the micro-injection mechanism can drive the injection piston to move upwards from the lower limit position to the upper limit position and simultaneously drive the needle replacing mechanism to complete the first motion state.

Description

Full-automatic micro-injection device

Technical Field

The invention relates to the technical field of microinjection, in particular to a full-automatic microinjection device.

Background

Microinjection has been widely used in the treatment of diabetes, gynecological clinical, and ophthalmic diseases, and is also commonly used in ICU wards, because of its advantages of small injection amount, high injection precision, adjustable injection amount, and easy absorption by patients.

The obligation personnel in the ICU branch of academic or vocational study are when carrying out the injection of trace liquid medicine, often will carry out accurate, trace, even, the injection that lasts to the liquid medicine, but present injection method is all through the manual self-injection of medical staff, because different medical staff's self technique and experience are different, can lead to the fact different influences to the injection result, aggravate medical staff's work greatly, even when can not guarantee to inject, if medical staff's error, then can cause the secondary injury to the patient health, in the long run, just increased medical staff's work burden.

In the treatment of diabetes, there are two needs: continuous trace administration is carried out at ordinary times; ② large dose administration before meal. Each patient injected with insulin uses the disposable injection device 2-3 times a day, and uses 60-90 discarded syringe needles in 1 month. During the injection process of the diabetes medicine, even after the injection process is used, the needle head can bring human body cells into the pen core, infectious cells can return into the needle head, and the virus can be spread by needle stick injury caused by the needle heads at two ends. The risk of needle stick injuries also extends to downstream workers, such as garbage handlers, cleaning personnel, incinerators, and the general public.

The prior art takes little comprehensive consideration and is generally a micro-injector. For example, in order to solve the technical problem that the traditional injection cannot ensure the accuracy of the injection amount of liquid medicine, the micro-injection pump device (CN109675142A, 20190426) in ICU department in hunan elegance hospital of southern and central university drives the stepping motor 18 to rotate, the stepping motor 18 drives the gear rod 38 to rotate, the gear disc 37 meshed and connected with the gear rod 38 rotates along with the gear rod and drives the lead screw 33 to rotate, the half nut 32 fixed on the U-shaped sliding block 34 moves in parallel along the axial direction of the lead screw under the rotation of the lead screw 33, the U-shaped sliding block 34 horizontally slides on the guide rod 30 and pulls the round sleeve 27 to contract, and the push-pull seat 13 pushes the injection handle of the injector 15 under the pulling of the round sleeve 27, thereby completing the continuous micro-injection of the injector 15. The problem of microinjection is only solved, but the problem of frequent needle replacement is not solved.

Therefore, designing a micro-injection device capable of automatically replacing a new needle, automatically protecting an old needle and automatically injecting is a difficult problem which needs to be solved urgently in the industry.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a fully automated microinjection apparatus, which can automatically perform microinjection, and simultaneously automatically replace a new needle and protect an old needle, thereby completely performing microinjection automation.

The object of the invention is achieved in that a fully automatic microinjection device comprises an injector having a barrel and an injection piston which is a watertight sliding fit in the barrel between an upper limit position and a lower limit position, comprises

The needle head replacing mechanism is provided with n injection needles in a central symmetry manner by a sun shaft, wherein n is a natural number more than or equal to 3; the needle changing mechanism is switched between a first motion state at a lower position and a second motion state at an upper position, and at the lower position, the needle changing mechanism moves down a safety distance, the first motion state: the needle head replacing mechanism rotates to replace the included angle alpha,

is not usedThe injection needle is aligned with the needle cylinder; in the upper position, the unused injection needle) is water-tightly interfaced with the barrel, a second movement state: the needle head replacing mechanism idles;

the micro-injection mechanism is simultaneously in driving connection with the injector and the needle head replacement mechanism, and in the upper position, the micro-injection mechanism can drive the injection piston to move downwards from the upper limit position to the lower limit position and simultaneously drive the needle head replacement mechanism to complete a second motion state; in the lower position, the micro-injection mechanism can drive the injection piston to move upwards from the lower limit position to the upper limit position and simultaneously drive the needle replacing mechanism to complete the first motion state.

Further, the needle head replacement mechanism comprises a sun gear, at least n planetary gears and a gear ring, wherein the at least n planetary gears are fixed on the planet carrier plate, and n is a natural number which is more than or equal to 3; the sun gear is fixedly connected with the sun shaft, and the n injection needles are respectively coaxially arranged on the planet carrier plate in a telescopic way with the planet gear 22.

Further, the micro-injection mechanism comprises a worm, a first turbine and a second turbine, wherein the first turbine and the second turbine are respectively meshed with two sides of the worm; the first turbine is fixedly connected with a driving nut, the driving nut is in spiral fit with an injection screw rod, the injection screw rod is integrally connected with an injection piston, and the second turbine is fixedly connected with the sun shaft.

Further, the needle head replacing mechanism is arranged in the needle head bin shell, the inner wall of the needle head bin shell is provided with a telescopic stop pin over against the gear ring, the telescopic stop pin is connected with an electromagnetic opening and closing device, the electromagnetic opening and closing device enables the telescopic stop pin to be switched between an extending position and a retracting position, the telescopic stop pin abuts against the outer cylindrical surface of the gear ring and stops the gear ring at the extending position, and the telescopic stop pin retracts to the inner wall of the needle head bin shell at the retracting position.

Further, the first motion state specifically is: the telescopic stop pin abuts against the outer cylindrical surface of the gear ring to stop the gear ring, so that the gear ring is fixed, and the sun gear rotates to drive the planet rack plate, the planet gear and the injection needle to rotate; the second motion state is: the unused injection needle is in watertight butt joint with the needle cylinder, so that the planet rack plate is fixed, the sun gear rotates to drive the gear ring to rotate, and the gear ring rotates to realize idle running of the needle head replacing mechanism.

Furthermore, the middle part of the sun shaft is connected with a telescopic adjusting mechanism, and the telescopic adjusting mechanism is switched between an extension position and a contraction position to drive the needle head replacing mechanism to be switched between an upper position and a lower position.

Furthermore, the sun shaft comprises an upper sun half shaft and a lower sun half shaft which are disconnected, the telescopic adjusting mechanism comprises an upper half butt joint part and a lower half butt joint part, the upper half butt joint part is connected with the upper sun half shaft, the lower half butt joint part is connected with the lower sun half shaft, and the lower half butt joint part slides in the guide groove of the sliding frame in a guiding manner; the upper half butt joint part and the lower half butt joint part are provided with electromagnetic opening and closing devices.

Further, the bottom of the needle cylinder is in threaded connection with a lower valve seat, the lower valve seat is integrally connected with a conical butt joint part, the conical butt joint part comprises an inner cone and an outer cylinder, an insertion part is formed between the inner cone and the outer cylinder, an elastic body is arranged in the insertion part, and a positioning groove is formed in the outer wall of the inner cone; the injection needle comprises a conical sleeve, the inner wall of the conical sleeve is provided with a positioning rib, and the unused injection needle is in watertight butt joint with the needle cylinder: the inner cone is inserted into the conical sleeve of the injection needle until the positioning rib is pressed into the positioning groove, and simultaneously, the top of the conical sleeve is pressed into the elastic body in a liquid-tight manner.

The injection frame comprises an outer sheath and a shaft support which are integrally connected, the top of the syringe needle cylinder is fixedly connected with an upper guide seat in a watertight manner, and the upper guide seat and the lower valve seat are fixed in the outer sheath through fixing blocks respectively; the middle part of the sun shaft is fixed in the shaft support.

Furthermore, the lower valve seat is provided with a first one-way valve, the needle cylinder is provided with a liquid inlet at the lower limit position, an exhaust port at the upper limit position, and the liquid inlet is also provided with a second one-way valve.

The fully-automatic micro-injection device aims at solving the technical problems of automatically replacing a new needle, automatically protecting an old needle and automatically injecting, and adopts the following technical means:

1) the needle head replacing mechanism is cooperated with the downward and upward injection actions of the injection piston

The needle head replacing mechanism 20 adopts a planetary gear mechanism, each planetary gear is coaxially provided with an injection needle, the needle head replacing mechanism has two motion states, namely a first motion state, when the injection needle is in watertight butt joint with the needle cylinder, the planet rack plate and the planetary gears are not moved, the sun gear rotates to drive the gear ring to rotate, and idle rotation is realized; at the moment, the injection piston descends to finish liquid discharging by injection; in the second motion state, the needle replacing mechanism moves downwards by a safe distance L, the gear ring is fixed, the sun gear rotates to drive the planet carrier plate and the planet gear to rotate through a replacing included angle alpha,

at the moment, the injection piston moves downwards to finish the return liquid suction;

2) the micro-injection mechanism 30 achieves the cooperative coordination of the above actions

The micro-injection mechanism is characterized in that a stepping motor drives a worm, the worm is simultaneously driven and meshed with a first turbine and a second turbine, the first turbine drives a driving nut, the driving nut and an injection screw form a screw-nut pair, and the driving nut drives the injection screw and the injection piston to realize the descending or ascending of the injection piston. Meanwhile, the second turbine drives the sun shaft to realize two motion states of the needle head replacing mechanism.

The invention not only considers the problem of the intramuscular injection of the injector, but also considers the problem of the replacement of the needle head of the injector for each injection, greatly improves the automation degree of the micro-injection device by the mutual cooperative match of the two structures, reduces the labor intensity for frequently changing the needle head of the micro-injection with high frequency, and is particularly suitable for the micro-injection of the diabetes treatment and the requirement of the frequent micro-injection of an ICU chamber.

Drawings

FIG. 1 is a front sectional view of a fully automated microinjection apparatus according to the present invention in an injection state.

FIG. 2 is a front sectional view of a fully automated microinjection apparatus of the present invention in a needle change position.

Fig. 3 is a front cross-sectional view of a fully automated microinjection apparatus of the present invention replacing a new set of unused needles.

Reference numerals in the above figures:

1 first button, 2 second buttons, 3 injection racks, 4 outer sheaths, 5 first one-way valves, 6 telescopic stop pins and 7 second one-way valves

11 syringes, 12 injection pistons, 13 upper guide seats, 14 piston screw rods, 15 conical butt joint parts, 16 elastic bodies, 18 lower valve seats and 19 positioning grooves

20 needle changing mechanism, 21 sun gear, 22 planet gear, 23 ring gear, 24 planet carrier plate, 25 sun shaft, 26 injection needle, 27 placing hole, 28 ring-shaped blocking rib and 29 needle chamber shell

30 microinjection mechanism, 31 worm, 32 first worm gear, 33 second worm gear, 34 drive nut

40 telescopic adjusting mechanism, 41 upper half butt joint part, 42 lower half butt joint part, 43 sliding frame, 44 guide groove, 45 electromagnetic opening and closing device, 46 permanent magnet and 47 electromagnet

15.1 inner cone, 15.2 outer cone, 15.3 inserting part, 47.1 iron core and 47.2 coil

26.1 needle, 26.2 needle seat, 26.3 taper sleeve, 26.4 positioning part and 26.5 annular convex rib

29.1 left half wall, 29.2 right half wall, 29.3 needle outlet hole, 29.4 needle hole cover

Detailed Description

The following detailed description of the embodiments of the present invention is provided in connection with the accompanying drawings, but is not intended to limit the scope of the invention.

As shown in the figure, the fully automatic micro-injection device comprises an injector, the injector comprises a syringe 11 and an injection piston 12, and the injection piston 12 is at an upper limit position P in the syringe 11₁And a lower limit position P₂The upper guide seat 13 is fixedly connected with the top of the needle cylinder 11 in a watertight and sealed way, the bottom of the needle cylinder 11 is connected with a lower valve seat 18 in a threaded way, and the lower valve seat 18 is integrally connected with a conical butt joint part 15; the upper guide seat 13 and the lower valve seat 18 are respectively fixed in the outer sheath 4 of the injection frame 3 through fixing blocks. The conical butt joint part 15 comprises an inner cone 15.1 and an outer cylinder 15.2, an insertion part 15.3 is formed between the inner cone 15.1 and the outer cylinder 15.2, and an elastic body 16 is arranged in the insertion part 15.3. The injection piston 12 is integrally connected to a piston screw 14. The injection needle 26 comprises a needle head 26.1 and a needle seat 26.2, the needle seat 26.2 comprises a conical sleeve 2 which is integrally connected from top to bottom6.3, a detent 26.4 and an annular bead 26.5. The inner hole of the conical sleeve 26.3 is matched with the inner cone 15.1 in a same taper way. Inner cone 15.1 is inserted into conical sleeve 26.3 of the injection needle, while the top of conical sleeve 26.3 is pressed liquid-tightly into elastomer 16. The lower valve seat 18 is provided with a one-way valve 5, and the lower limit position P of the needle cylinder 11₂Is provided with a liquid inlet and an upper limit position P₁An exhaust port is arranged, and a check valve 5 is arranged at the liquid inlet.

The needle replacing mechanism 20 is arranged below the injector, and the injection piston 12 and the needle replacing mechanism 20 are respectively connected with the micro-injection mechanism 30 in a driving way. The micro-injection mechanism 30 is fixed to the injection rack 3.

The needle changing mechanism 20 includes a sun gear 21, at least n planetary gears 22 and a ring gear 23, at least n planetary gears 22 are fixed on a planet carrier plate 24, and n is a natural number greater than or equal to 3. The sun gear 21, planet gears 22, ring gear 23 and planet gear mechanism of the planet carrier plate 24 are arranged in a needle magazine housing 29. Sun gear 21 is fixedly connected to sun shaft 25. The planet carrier plate 24 is provided with injection needles 26 coaxially and telescopically with the planet gears 22, so that adjacent injection needles 26 have a changing angle alpha therebetween,

specifically, the planet carrier plate 24 is provided with a placing hole 27 coaxially with the planet gear 22, the top opening of the placing hole 27 is provided with an annular blocking rib 28, a spring is arranged inside the placing hole, and the positioning part 26.4 is in clearance fit with the placing hole 27, so that the coaxial positioning of the injection needle 26, the placing hole 27 and the planet gear 22 is completed. The annular rib 26.5 of the injection needle 26 is forcibly pressed into the annular blocking rib 28 at the top of the placing hole 27, the top of the spring is abutted against the bottom of the annular rib 26.5 of the injection needle 26, so that the injection needle 26 is switched between a normal position and a pressing-down position, the annular rib 26.5 is abutted against the annular blocking rib 28 at the normal position, the bottom of the annular rib 26.5 is abutted against the spring to a limit compression position at the pressing-down position, and the needle head extends out of the needle head bin shell 29. The needle changing mechanism 20 has two motion states, the first motion state is that the gear ring 23 is fixed, and the sun gear 21 rotates to drive the planet carrier plate to rotate.

The micro-injection mechanism 30 comprises a worm 31, a first worm wheel 32 and a second worm wheel 33, wherein the first worm wheel 32 and the second worm wheel 33 are respectively meshed with two sides of the worm 31; the first worm gear 32 is fixedly connected to a drive nut 34, and the drive nut 34 is in threaded engagement with the piston screw 14. The inner hole of the second turbine 33 is connected with the sun shaft 25 through a key. The worm 31 is connected with a stepping motor through a coupler.

The sun shaft 25 includes sun upper and sun lower half shafts that are disconnected. A telescoping adjustment mechanism 40 is connected to the middle of sun shaft 25, and telescoping adjustment mechanism 40 causes needle exchange mechanism 20 to switch between the upper and lower positions. The telescopic adjusting mechanism 40 comprises an upper half butt joint part 41 and a lower half butt joint part 42, wherein the upper half butt joint part 41 is connected with the upper sun half shaft, and the lower half butt joint part 42 is connected with the lower sun half shaft 25.2. The lower half butting portion 42 is guided and slid in a guide groove 44 of a sliding frame 43, and the sliding frame 43 is integrally supported by a shaft. The upper half butt joint part 41 and the lower half butt joint part 42 comprise an electromagnetic opening and closing device 45, specifically, the electromagnetic opening and closing device 45 comprises at least one permanent magnet 46 arranged on the upper half butt joint part 41 and an electromagnet 47 arranged on the lower half butt joint part 42 corresponding to the permanent magnet, the electromagnet 47 comprises an iron core 47.1 and a coil 47.2, the coil 47.2 is powered by a control circuit, when the coil is powered in the forward direction, the electromagnet 47 generates magnetism the same as the magnetic pole of the permanent magnet 46 to generate repulsive force, the lower half butt joint part 42 can be bounced to the lower end of the guide groove 44, the telescopic adjusting mechanism 40 is located at an extension position, at the moment, the lower half butt joint part 42 drives the sun lower half shaft and the needle replacing mechanism 20 to move downwards, the injection needle 26 is separated from the lower valve seat 14, the sun shaft 25 is in an extension state, and a planet carrier of the needle replacing mechanism 20 can rotate to replace the new injection needle 26. When the coil is electrified reversely, the electromagnet 47 generates magnetism opposite to the magnetic pole of the permanent magnet 46 to generate attraction force, the permanent magnet 46 attracts the iron core 47.1 to attract the upper half butt joint part 41 and the lower half butt joint part 42 together, and the telescopic adjusting mechanism 40 is in a contraction position, so that the sun lower half shaft moves upwards, and the new injection needle 26 is connected with the lower valve seat 18 in a watertight and plugging manner.

The needle exchange mechanism 20 is switched between the upper and lower positions by the action of the telescopic adjustment mechanism 40. The inner wall of the needle head bin shell 29 is provided with a pin mounting hole right facing the gear ring 23, a telescopic stop pin 6 is arranged in the pin mounting hole, the telescopic stop pin 6 is connected with an electromagnetic opening and closing device, the electromagnetic opening and closing device enables the telescopic stop pin 6 to be switched between an extending position and a retracting position, the telescopic stop pin 6 abuts against the outer cylindrical surface of the gear ring to stop the gear ring 23 at the extending position, and the telescopic stop pin 6 retracts into the pin mounting hole at the retracting position.

When the needle replacing mechanism 20 is at the lower position, the telescopic stop pin 6 extends out to abut against the outer wall of the gear ring, and the gear ring 23 is stopped, so that the needle replacing mechanism 20 is changed into a first motion state, the gear ring 23 is fixed, the sun gear 21 rotates, and the planet carrier plate 24 is driven to rotate by a replacing included angle alpha. When the needle replacing mechanism 20 is at the upper position, a new injection needle 26 is in watertight plug-in connection with the lower valve seat 18, and the telescopic stop pin 6 retracts, so that the needle replacing mechanism 20 is changed into a second motion state, the planet carrier plate 24 is not moved, the sun gear 21 rotates, and the gear ring 23 is driven to rotate. The rotation of the sun gear 21 is caused by the rotation of the worm 31 to actuate the driving of the second worm gear 33, the rotation of the worm 31 simultaneously actuates the first worm gear 31, and the rotation of the first worm gear 31 and the driving nut 34 drives the piston screw 14 and the injection piston 12 to move downwards, thereby completing the micro-injection work.

The injection frame 3 is provided with a first button 1 and a second button 2, and the first button 1 is connected with a telescopic adjusting mechanism 40 and a telescopic stop pin 6. The second button 2 switch is connected to the micro-injection mechanism 30. The first button 1 is a sliding button, the first button 1 sliding between an injection position, a rest position and a needle replacement position. The rest position is located at the midpoint of the injection position and the needle replacement position.

For protecting the used injection needle and replacing the new injection needle, because the injection needle contacts the blood and body fluid of the patient, the used injection needle belongs to the medical contamination, preferably, the upper wall of the needle bin cover 29 comprises a telescopic left half wall 29.1 and a telescopic right half wall 29.2, the lower wall of the needle is provided with a needle extending hole 29.3, the lower wall of the needle bin cover 29 is movable up and down (not shown), after n injection needles in the needle bin shell 29 are used, a needle hole cover 29.3 is covered, the lower wall is moved up, the conical sleeve 26.3 of the injection needle 26 is pressed down by the upper wall, the needle 26.1 is forcibly pressed into the needle seat 26.2, the left half wall 29.1 and the right half wall 29.2 are removed, and the injection needle 26 is respectively taken away and thrown into a medical garbage special box. The fully automated microinjection apparatus may be reused by cleaning the needle cartridge housing 29 and reinserting a new needle 26.

The action of the fully automated microinjection apparatus is as follows:

the fully automated microinjection apparatus automatically performs two functions: firstly, an injection function; namely, the injection action of the piston moving downwards and the liquid inlet action of the piston moving upwards; the needle head is automatically replaced, and the function is completed at the same time when the piston moves upwards. The needle replacement mechanism 20 is switched between an upper position, in which a microinjection function is performed, and a lower position, in which an automatic needle replacement function is performed. The needle changing mechanism 20 has two motion states, the first motion state is that the gear ring 23 is fixed, and the sun gear 21 rotates to drive the planet carrier plate to rotate. The first motion state corresponds to an automatic needle change function and a down position. The second motion state is that the planet carrier plate 24 is stationary and the sun gear 21 rotates, driving the ring gear 23 to rotate. The second motion state corresponds to an injection function and an up position.

The specific operation is as follows:

when the first push button 1 is slid to the needle replacement position, the coil is energized in the forward direction, the sun shaft 25 is extended, and the injection needle 26 is separated from the lower valve seat 18. At the same time, the telescopic stop pin 6 is actuated to the extended position. When the first button 1 slides to a needle replacing position, the second button 2 is activated, the second button 2 is pressed, the micro-injection mechanism 30 is started, the worm 31 is driven by the stepping motor to rotate anticlockwise, the worm 31 simultaneously drives the first turbine 32 and the second turbine 33 to rotate respectively, the needle replacing mechanism 20 is driven by the second turbine 33 to move according to a first motion state, finally, the needle replacing mechanism rotates through a replacing included angle alpha, meanwhile, the first turbine 33 drives the driving nut 34 to rotate, and the driving nut 34 drives the piston screw rod 14 to ascend to the upper limit position of the needle cylinder;

when the first button 1 slides to an injection position, the coil is electrified reversely, the sun shaft 25 is in a shortened state, the sun shaft 25 drives a new injection needle 26 to be plugged in the lower valve seat 18 upwards in a watertight manner, and when the first button 1 slides to the injection position, the second button 2 is activated, the second button 2 is pressed to start the micro-injection mechanism 30, the worm 31 is driven by the stepper motor to rotate clockwise, the worm 31 simultaneously drives the first turbine 32 and the second turbine 33 to rotate respectively, the needle replacing mechanism 20 is driven by the second turbine 33 to move according to a second motion state, and the gear ring 23 idles; meanwhile, the first turbine 32 drives the driving nut 34 to rotate, and the driving nut 34 drives the piston screw rod 14 to move downwards to the lower limit position of the needle cylinder, so that micro-injection work is completed. The second button 2 is required because of the manual penetration into the muscle prior to injection.

The first push button 1 is slid to the rest position and if the first push button 1 is slid from the injection position to the rest position, the control mechanism actuates the telescopic adjustment mechanism 40 such that the telescopic adjustment mechanism 40 is in the extended position. In addition, the power supply of the stepping motor and the first button is stopped, and the full-automatic micro-injection device is in a non-operating state. At this point, a new needle 26 may be replaced.

The full-automatic micro-injection device utilizes the same worm to drive the two turbines simultaneously, the worm rotates clockwise, the piston descends, the gear ring idles to complete the injection function, the worm piston rotates anticlockwise to move upwards while the planet carrier plate rotates to complete the needle head replacement function, the injection function and the needle head replacement function are completed by the cooperation of the same micro-injection mechanism, and the automation degree of the micro-injection device is greatly improved.

Claims

1. A fully automated microinjection device comprises an injector, which comprises a syringe (11) and an injection piston (12), the injection piston (12) being in an upper limit position (P) in the syringe (11)₁) And a lower limit position (P)₂) Is in water-tight sliding fit and is characterized by comprising

The needle head replacing mechanism (20), n injection needles (26) are arranged in the needle head replacing mechanism (20) in a centrosymmetric manner through a sun shaft (25), and n is a natural number which is more than or equal to 3; the needle changing mechanism (20) is switched between a first movement state in a lower position, in which the needle changing mechanism (20) is moved down by a safety distance (L), and a second movement state in an upper position, the first movement state: the needle changing mechanism (20) rotates through a changing included angle alpha,

aligning the unused injection needle (26) with the barrel (11); in the upper position, the unused injection needle (26) is in water-tight abutment with the needle cylinder (11), the second movement state: the needle changing mechanism (20) idles;

a micro-injection mechanism (30), said micro-injection mechanism (30) driving the connecting syringe and the needle changing mechanism (20) simultaneously, in the upper position, said micro-injection mechanism (30) being capable of driving the injection piston from the upper limit position (P)₁) Move down to the lower extreme position (P)₂) Simultaneously driving the needle replacing mechanism (20) to complete the second motion state; in the lower position, the micro-injection mechanism (30) is able to drive the injection piston from a lower limit position (P)₂) Move up to the upper limit position (P)₁) Simultaneously, the needle changing mechanism (20) is driven to complete the first motion state.

2. A fully automated microinjection apparatus according to claim 1, wherein the needle changing mechanism (20) comprises a sun gear (21), at least n planetary gears (22) and a ring gear (23), at least n planetary gears (22) being fixed to a carrier plate (24), n being a natural number equal to or greater than 3; the sun gear (21) is fixedly connected with the sun shaft (25), and the n injection needles (26) are respectively coaxially arranged on the planet carrier plate (24) in a telescopic way with the planet gear (22).

3. The fully automated microinjection apparatus according to claim 2, wherein the microinjection mechanism (30) comprises a worm (31), a first worm wheel (32), and a second worm wheel (33), the first worm wheel (32) and the second worm wheel (33) being engaged with both sides of the worm (31), respectively; the first turbine (32) is fixedly connected with a driving nut (34), the driving nut (34) is in screw fit with the injection screw rod (14), the injection screw rod (14) is integrally connected with the injection piston (12), and the second turbine (33) is fixedly connected with the sun shaft (25).

4. A fully automated microinjection apparatus according to claim 3, wherein the needle changing mechanism is disposed in the needle magazine housing (29), the inner wall of the needle magazine housing (29) is provided with a retractable stopping pin (6) facing the gear ring (23), the retractable stopping pin (6) is connected to an electromagnetic opening/closing device, the electromagnetic opening/closing device switches the retractable stopping pin (6) between an extended position in which the retractable stopping pin (6) abuts against the outer cylindrical surface of the gear ring to stop the gear ring (23) and a retracted position in which the retractable stopping pin (6) retracts into the inner wall of the needle magazine housing (29).

5. The fully automated microinjection device according to claim 4, wherein the first motion state is in particular: the telescopic stop pin (6) abuts against the outer cylindrical surface of the gear ring to stop the gear ring (23) so that the gear ring (23) is fixed, and the sun gear (21) rotates to drive the planet rack plate (24), the planet gear (22) and the injection needle (26) to rotate; the second motion state is: the unused injection needle (26) is in watertight butt joint with the needle cylinder (11) so that the planet carrier plate (24) is fixed, the sun gear (21) rotates to drive the gear ring (23) to rotate, and the gear ring (23) rotates to realize idle rotation of the needle head replacing mechanism (20).

6. A fully automated microinjection apparatus according to any one of claims 2 to 5, wherein a retractable adjustment mechanism (40) is connected to the central portion of the sun shaft (25), and the retractable adjustment mechanism (40) is switched between the extended position and the retracted position, thereby switching the needle changing mechanism (20) between the upper position and the lower position.

7. The fully automated microinjection device according to claim 1, wherein the sun shaft (25) comprises a sun upper half shaft and a sun lower half shaft which are disconnected, the retractable adjustment mechanism (40) comprises an upper half abutment (41) and a lower half abutment (42), the upper half abutment (41) is connected to the sun upper half shaft, the lower half abutment (42) is connected to the sun lower half shaft, and the lower half abutment (42) is slidably guided in the guide groove (44) of the carriage (43); the upper half butt joint part (41) and the lower half butt joint part (42) are provided with electromagnetic opening and closing devices (45).

8. A full automatic micro-injection device according to claim 3, characterized in that the bottom of the syringe (11) is connected with a lower valve seat (18) by screw threads, the lower valve seat (18) is integrally connected with a conical butt joint part (15), the conical butt joint part (15) comprises an inner cone (15.1) and an outer cone (15.2), a plug-in part (15.3) is formed between the inner cone (15.1) and the outer cone (15.2), an elastic body (16) is arranged in the plug-in part (15.3), and a positioning groove (19) is arranged on the outer wall of the inner cone (15.1); the injection needle (26) comprises a conical sleeve (26.3), the inner wall of the conical sleeve (26.3) is provided with a positioning rib (17), and the unused injection needle (26) is in watertight butt joint with the needle cylinder (11) and comprises the following components: the inner cone (15.1) is inserted into the conical sleeve (26.3) of the injection needle until the positioning ribs (17) are pressed into the positioning grooves (19), and simultaneously the top of the conical sleeve (26.3) is pressed into the elastomer (16) in a fluid-tight manner.

9. The full-automatic micro-injection device according to claim 8, which comprises an injection frame (3), wherein the injection frame (3) comprises an outer sheath (4) and a shaft support which are integrally connected, an upper guide seat (13) is fixedly connected to the top of the injector syringe (11) in a water-tight manner, and the upper guide seat (13) and a lower valve seat (18) are respectively fixed in the outer sheath (4) through fixing blocks; the middle part of the sun shaft is fixed in the shaft support.

10. A fully automatic microinjection device according to claim 8, wherein the lower valve seat (18) is provided with a first check valve (5), the needle cylinder (11) being in the lower limit position (P)₂) Is provided with a liquid inlet at an upper limit position (P)₁) An exhaust port is arranged at the position, and a second one-way valve (7) is also arranged at the liquid inlet.