CN108404257B

CN108404257B - Safety insulin needle

Info

Publication number: CN108404257B
Application number: CN201810117903.6A
Authority: CN
Inventors: 张洪杰; 王兴国
Original assignee: Beipu Medical Technology Co ltd
Current assignee: Beipu Medical Technology Co ltd
Priority date: 2018-02-06
Filing date: 2018-02-06
Publication date: 2023-06-30
Anticipated expiration: 2038-02-06
Also published as: WO2019153556A1; CN108404257A

Abstract

The invention discloses a safe insulin needle which comprises a sheath, a needle tube, a safe sheath and a needle seat, wherein the needle tube is arranged on a central shaft of the needle seat and distributed along the central shaft, an assembling cavity is formed at the lower part of the needle seat, the lower end of the needle tube extends into the assembling cavity, a needle tube assembling base is formed at the upper part of the needle seat, the upper end of the needle tube extends upwards to the upper part of the needle tube assembling base, the outer part of the needle seat is sleeved with the safe sheath, and a locking structure is formed between the inner wall of an inner cavity of the safe sheath and the outer wall of the needle seat. The technical effects are as follows: the product has simple and practical integral structure, small volume, compact matching degree among all parts, further simplified assembly process and one-time assembly. The locking structure of the product is stable, and the clockwise, anticlockwise and axial locking can be realized simultaneously, so that the safety coefficient of the product is effectively improved.

Description

Safety insulin needle

Technical Field

The invention relates to the technical field of medical instruments, in particular to a safe insulin needle, and particularly relates to a mechanical connecting structure of the safe insulin needle.

Background

Comparison document, application number: 201420663437.9, filing date: 2014.11.10 patentees: the utility model discloses a disposable safe self-destroying insulin needle, which is characterized in that a needle seat is arranged in an insulin needle body, the needle seat is integrally cylindrical, the cavity of the cylindrical needle seat is hollow, a needle tube substrate is arranged in the cavity of the needle seat, the needle tube substrate divides the cavity of the needle seat into an upper independent space and a lower independent space, internal threads are distributed on the inner wall of the lower independent space, a spring fixing column is arranged at the center position of the upper surface of the needle tube substrate, the lower section of the spring fixing column is positioned in the upper independent space, a needle tube is arranged at the needle tube substrate, one end of the needle tube penetrates through the needle tube substrate, extends upwards after penetrating through the spring fixing column positioned at the center position of the needle tube substrate, the other end of the needle tube penetrates through the needle tube substrate and extends downwards into the lower independent space, both ends of the needle tube are in a stab tip shape, at least one elastic sheet is distributed on the inner wall of the independent space at the upper part of the needle tube, the elastic sheet is obliquely arranged on the inner wall of the inner cavity of the needle tube, one end of the elastic sheet is connected with the inner wall of the inner cavity of the needle tube, the other end of the elastic sheet is suspended, the suspended end points to the upper surface of the needle tube substrate and is close to the center, a spring is sleeved outside the spring fixing column, one end of the spring downwards props against the upper surface of the needle tube substrate, the other end of the spring upwards props against the safety sheath, a safety clamping seat is sleeved at the upper end of the needle seat, the lower end of the safety clamping seat and the upper end of the needle seat are mutually sleeved, the upper end of the safety clamping seat is provided with a safety sheath, the whole safety clamping seat is cylindrical, the inner cavity of the safety clamping seat is hollow, an annular limiting part is formed at the inner edge of the opening at the upper end of the safety clamping seat, the whole safety sheath is also cylindrical, the inner cavity of the safety sheath is hollow, the outer edge of the opening of the lower end of the safety sheath forms an annular limit bulge matched with the annular limit part, the annular limit bulge is positioned in a cavity of the safety clamping seat below the annular limit part, the upper end face of the annular limit bulge can downwards prop against the lower end face of the annular limit part, the outer edge of the opening of the lower end of the safety sheath and the inner edge of the opening of the upper end of the safety clamping seat are mutually limited and sleeved, the outer part of the spring is sleeved with a self-destroying seat, the self-destroying seat is integrally cylindrical, the inner cavity of the self-destroying seat is hollow, the outer diameter of the upper section of the self-destroying seat is smaller than the outer diameter of the lower section of the self-destroying seat, an annular limit step is formed between the upper section of the self-destroying seat and the lower section of the self-destroying seat, the outer diameter of the self-destroying seat is larger than the diameter of the inner cavity of the safety sheath, the outer diameter of the self-destroying seat is smaller than or equal to the diameter of the inner cavity of the safety sheath, the end face of the annular limit step is propped against the end face of the lower end of the safety sheath, the outer wall of the self-destroying seat is formed with an annular bulge matched with an elastic sheet, the outer diameter of the self-destroying seat is perpendicular to the upper end of the needle tube, the upper end of the needle tube is perpendicular to the upper end of the needle tube is provided with a closed, and the upper end of the needle tube is perpendicular to the upper end of the needle tube.

The existing similar products can realize the safe self-destruction function, but the product has larger volume and higher cost due to the structural limitation.

Disclosure of Invention

The invention aims to provide a safe insulin needle, which consists of four main body parts, has simple assembly procedures and assembly structures and has stable working state. The product has small volume and low cost, realizes the safety function with lower cost, and overcomes the defects and shortcomings in the prior art.

In order to achieve the above object, in the embodiment of the invention, a safety insulin needle is disclosed, which comprises a sheath, a needle tube, a safety sheath and a needle seat, wherein the needle tube is arranged on a central shaft of the needle seat and distributed along the central shaft, an assembling cavity is formed at the lower part of the needle seat, the lower end of the needle tube extends into the assembling cavity, a needle tube assembling base is formed at the upper part of the needle seat, the upper end of the needle tube extends upwards to the upper part of the needle tube assembling base, the outer part of the needle seat is sheathed with the safety sheath, a locking structure in a three-dimensional space is formed between the inner wall of the inner cavity of the safety sheath and the outer wall of the needle seat, and the outer part of the safety sheath is sheathed with the sheath, and a lateral rotation preventing structure is formed between the inner wall of the inner cavity of the sheath and the outer wall of the safety sheath.

A method of using a safety insulin needle, as shown in fig. 13 to 32, the steps of the method of using are as follows:

the safety insulin needle is screwed into the insulin pen clockwise, the internal thread of the needle seat assembly cavity is matched with the external thread at the end part of the insulin pen, and in the clockwise rotation process, the limit step and the limit plane are driven to be gradually contacted and finally meshed, so that the safety sheath is prevented from being pulled out when the sheath is pulled out;

at the moment, the convex points of the safety sheath are in interference fit with the lower convex points of the needle seat, and the convex points are positioned below the lower convex points and used for preventing the safety sheath from upwards moving without any person;

after injection is completed, the safety sheath is rotated anticlockwise to be in place, so that the end face of the limit step is separated from the limit plane;

then, the safety sheath is pulled upwards, the convex points finally upwards pass through the upper convex points, at the moment, the upper convex points form temporary reverse limiting positions for the convex points, and the limiting rings upwards prop against the limiting blocks and are used for limiting the upward displacement of the safety sheath;

at the moment, the safety sheath is rotated clockwise, and the limit convex strips easily slide into the locking area through the transition inclined plane;

the two sides of the locking area are respectively formed with an anti-reverse platform and a blocking piece, and the limiting convex strips cannot rotate in the clockwise direction and the anticlockwise direction under the limiting action of the anti-reverse platform and the blocking piece;

on axis direction, the plane of the lower terminal surface of spacing sand grip is spacing by spacing platform, and the spacing collar is spacing by the stopper, and at this moment, safety sheath is in order, reverse rotation and upper and lower displacement are all spacing, can't remove and accomplish the auto-lock, and above-mentioned needle tubing is wrapped up by safety sheath is complete, and safety protection function is triggered.

The invention discloses a safe insulin needle, which has the technical effects that: the product has simple and practical integral structure, small volume, compact matching degree among all parts, further simplified assembly process and one-time assembly. The locking structure of the product is stable, and the clockwise, anticlockwise and axial locking can be realized simultaneously, so that the safety coefficient of the product is effectively improved.

Drawings

FIG. 1 is a schematic diagram of the structure of the present invention.

Fig. 2 is a schematic view of the jacket structure of the present invention.

FIG. 3 is a schematic cross-sectional view of the present invention.

Fig. 4 is a schematic view of the structure of the safety sheath of the present invention.

Fig. 5 is a perspective view of the safety shield of the present invention.

FIG. 6 is a schematic cross-sectional view of an embodiment of the safety sheath of the present invention.

Fig. 7 is a partial enlarged view of G in fig. 6.

Fig. 8 is a schematic view of the original locking state of the safety sheath and the needle seat.

Fig. 9 is a schematic view showing the structure of the needle holder of the present invention.

Fig. 10 is a partial enlarged view of H in fig. 9.

Fig. 11 is a first cross-sectional view of the assembled original locked state of the safety shield and the needle hub.

Fig. 12 is a perspective view of the hub of the present invention.

Fig. 13 is a first usage state diagram of the present invention.

Fig. 14 is a second usage state diagram of the present invention.

Fig. 15 is a second cross-sectional view of the safety shield assembled with the hub in an original state.

Fig. 16 is a perspective cross-sectional view of fig. 14.

Fig. 17 is a partial enlarged view of fig. 16 at a.

Fig. 18 is a third usage state diagram of the present invention.

Fig. 19 is a fourth usage state diagram of the present invention.

Fig. 20 is a perspective cross-sectional view of fig. 19.

Fig. 21 is a partial enlarged view at B in fig. 20.

Fig. 22 is a fifth usage state diagram of the present invention.

Fig. 23 is a partial enlarged view of fig. 22 at C.

FIG. 24 is a schematic view showing a process state of the limit protrusion passing through the transition slope.

Fig. 25 is a partial enlarged view of D in fig. 24.

Fig. 26 is a sixth usage state diagram of the present invention.

Fig. 27 is a perspective view of fig. 25.

Fig. 28 is a partial enlarged view of fig. 27 at E.

FIG. 29 is a schematic view showing the state that the limit protruding strip is locked in the locking area.

Fig. 30 is a partial cross-sectional view of the final locked condition of the safety shield and the needle hub.

Fig. 31 is a partial enlarged view of F in fig. 30.

Fig. 32 is a schematic view of the safety protection state of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1, in an embodiment of the present invention, a safety insulin needle is disclosed, which is distinguished from the prior art in that: the needle tube 2 is arranged on a central shaft of the needle base 4 and distributed along the central shaft, an assembling cavity 41 is formed at the lower part of the needle base 4, the assembling cavity 41 is used for abutting an insulin pen 7, the lower end of the needle tube 2 extends into the assembling cavity 41, a needle tube assembling base 46 is formed at the upper part of the needle base 4, the upper end of the needle tube 2 extends upwards to the upper part of the needle tube assembling base 46, a safety sheath 3 is sleeved outside the needle base 4, a locking structure is formed between the inner cavity inner wall of the safety sheath 3 and the outer wall of the needle base 4, the needle tube at the upper part of the needle base 4 can be completely covered in the final state of the safety sheath 3, the final position between the safety sheath 3 and the needle base 4 is relatively fixed, a sheath 1 is sleeved outside the safety sheath 3, an anti-lateral rotation structure is formed between the inner cavity inner wall of the sheath 1 and the outer wall of the safety sheath 3, and the needle tube 3 can be covered in the original state of the product.

In the specific implementation, as shown in fig. 2, the sheath 1 is formed by an upper part and a lower part, the inner cavity of the sheath 1 is hollow, the upper part of the sheath 1 is cone-shaped, the lower part of the sheath 1 is cylindrical, the diameter of the lower edge of the upper part of the sheath 1 is smaller than that of the lower part of the sheath 1, an annular positioning step 12 is formed at the joint of the upper part and the lower part of the sheath 1, a plurality of outer ring vertical strips 11 are formed on the inner cavity wall of the lower part of the sheath 1, and the top end of the upper part of the sheath 1 is closed.

In the specific implementation, as shown in fig. 3 and 4, the safety sheath 3 is formed by an upper portion and a lower portion, the inner cavity of the safety sheath 3 is hollow, the upper portion and the lower portion of the safety sheath 3 are both cylindrical, the diameter of the upper portion of the safety sheath 3 is smaller than that of the lower portion of the safety sheath 3, an annular platform 36 is formed at the connection position of the upper portion and the lower portion of the safety sheath 3, the annular platform 36 is matched with the positioning step 12, the annular platform 36 is propped against the positioning step 12 upwards, a plurality of protruding positioning strips 32 are distributed at the outer wall of the lower portion of the safety sheath 3, a vacancy surface 31 is formed at the outer wall between the adjacent positioning strips 32, the vacancy surface 31 is matched with the outer ring vertical strips 11 in a one-to-one correspondence manner, the vacancy surface 31 is in interference fit with the outer ring vertical strips 11, the plurality of positioning strips 32 are distributed on the outer wall surface of the lower portion of the safety sheath 3 in an annular equidistant manner, when the sheath 1 is assembled with the safety sheath 3, a relatively stable assembly structure is realized through interference fit between the upper end of the outer ring vertical strips 11, a needle penetrating hole 37 is formed at the top end of the upper end of the safety sheath 3, and the needle penetrating through the needle penetrating hole 37.

In the specific implementation, as shown in fig. 5, the safety sheath 3 is formed by an upper portion and a lower portion, the inner cavity of the safety sheath 3 is hollow, a plurality of protruding inner ring vertical bars 33 and at least one positioning vertical bar 35 are distributed on the inner cavity wall of the lower portion of the safety sheath 3, the inner ring vertical bars 33 and the positioning vertical bars 35 are annularly distributed on the inner cavity wall of the lower portion of the safety sheath 3, wherein a limit step 351 is formed at the lower end of the positioning vertical bar 35 in a way of deviating to one side, a pointed cone with a guiding function is formed at the lower end of the positioning vertical bar 35, and the limit step 351 is convexly distributed on the inner cavity wall of the lower portion of the safety sheath 3.

In a specific implementation, as shown in fig. 6, the safety sheath 3 is formed by an upper portion and a lower portion, the inner cavity of the safety sheath 3 is hollow, the inner wall of the inner cavity of the upper portion of the safety sheath 3 is provided with a limit protruding strip 38, the limit protruding strip 38 is provided with a protruding point 381, a plane 382 is formed at the lower end face of the limit protruding strip 38, and the limit protruding strip 38 is distributed in parallel with the axial direction of the safety sheath 3.

In the specific implementation, as shown in fig. 7, the inner wall of the inner cavity of the safety sheath 3 is provided with a limit ring 34 distributed in an annular shape, and the limit ring 34 is arranged in a convex shape on the inner wall of the inner cavity.

In the specific implementation, as shown in fig. 8, a plurality of limiting vertical bars 44 and at least one limiting bar 45 are distributed on the outer wall of the assembly cavity 41, the limiting vertical bars 44 and the limiting bars 45 are all in convex distribution on the outer wall of the assembly cavity 41, the limiting vertical bars 44 are matched with the inner ring vertical bars 33, the limiting bars 45 are matched with the positioning vertical bars 35, the lower ends of the limiting bars 45 form limiting planes 451 matched with the limiting steps 351, when the assembly is performed, the inner ring vertical bars 33 and the positioning vertical bars 35 are inserted from gaps between the limiting vertical bars 44 and the limiting bars 45, the safety sheath 3 rotates laterally, the limiting steps 351 are inserted below the limiting planes 451, the limiting steps 351 are propped against the limiting planes 451 upwards, and locking assembly of the original state between the safety sheath 3 and the needle seat is realized.

In specific implementation, as shown in fig. 9 and 10, a slide 6 matched with the limit raised strip 38 is formed at the outer wall of the needle tube assembling base 46, a lower protruding point 51 and an upper protruding point 42 which are distributed up and down are provided on the surface of the slide 6, a convex transition inclined plane 47 is provided on one side of the upper end of the slide 6, a locking area 49 is formed on one side of the transition inclined plane 47, a convex blocking block 50 is formed on one side of the locking area, the locking area 49 is located between the transition inclined plane 47 and the blocking block 50, an anti-reverse platform 471 is formed on the inner side of the transition inclined plane 47, the anti-reverse platform 471 and the inner side wall of the blocking block 50 on both sides of the locking area 49 are both flat walls, the inner side walls on both sides are used for limiting the limit raised strip 38, a limit platform 52 is formed on the lower end of the locking area 49, a plane 382 on the lower end of the limit raised strip 38 is used for limiting the axial displacement of the safety sheath 3, the slide 6 and the locking area 49 are alternately distributed at the outer wall of the needle tube assembling base 46, and a locking area 49 is provided between adjacent slide 6.

In particular, as shown in fig. 9, a stopper 48 protruding from the outer wall of the needle tube assembly base 46 is provided at the lower edge of the locking area 49, and the stopper 48 is matched with the stopper 34 to block the upward displacement of the stopper 34.

In the specific implementation, as shown in fig. 11 and 12, the needle holder 4 is composed of a needle tube assembly base 46 positioned at the upper part and an assembly cavity 41 positioned at the lower part, the outer diameter of the needle tube assembly base 46 is smaller than that of the assembly cavity 41, the connection part of the needle tube assembly base 46 and the assembly cavity 41 forms an annular needle holder platform 43, and as shown in fig. 12, an inner spiral 53 is formed on the inner cavity inner wall of the assembly cavity 41.

In use, as shown in fig. 13 to 32, the safety insulin needle is screwed into the end of the insulin pen 7 clockwise, in the process, the sheath 1 drives the safety sheath 3 to rotate simultaneously, simultaneously triggers the limit steps 351 to be inserted below the limit planes 451 and realize mutual engagement, the safety sheath is prevented from being pulled out when the sheath is pulled out, the safety sheath is assembled into the assembling cavity at the lower part of the needle seat 4 through the threaded structure, the convex points 381 and the lower convex points 51 of the safety sheath are in interference fit, the convex points 381 are positioned below the lower convex points 51, the lower convex points 51 are used for blocking the convex points 381, the safety sheath is prevented from moving upwards without any person, double protection is realized, as shown in fig. 16, after the injection is completed, the safety sheath is rotated anticlockwise to be in place, so that the limit steps 351 are separated from the limit planes 451, then, the safety sheath is pulled upwards, the protruding point 381 finally passes through the upper protruding point 42, the limit ring 34 is positioned below the bottom limit block 48 and is propped against the limit block 48 upwards, at this time, the safety sheath is rotated clockwise, the lower section of the limit protruding strip 38 can laterally pass through the transition inclined plane 47 in a homeotropic manner and fall into the locking area 49, under the limitation of the anti-reversion platform 471 and the blocking block 50, the lower section of the limit protruding strip 38 cannot rotate in the positive and negative (clockwise and anticlockwise) directions, the plane 382 at the lower end of the limit protruding strip 38 is downwards limited by the limit platform 52 in the axial direction, meanwhile, the limit ring 34 is upwards limited by the limit block 48, at this time, the lateral rotation and the vertical displacement of the safety sheath are both limited and locked, the aim of final self-locking is fulfilled, at this time, the upper end of the needle tube is completely covered in the safety sheath, and the starting of the safety protection function is completed.

The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described above. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.

Claims

1. Safety insulin needle, its characterized in that: the needle tube comprises a needle tube (2), a safety sheath (3) and a needle seat (4), wherein the needle tube (2) is arranged on a central shaft of the needle seat (4) and distributed along the central shaft, an assembly cavity (41) is formed at the lower part of the needle seat (4), the lower end of the needle tube (2) extends into the assembly cavity (41), a needle tube assembly base (46) is formed at the upper part of the needle seat (4), the upper end of the needle tube (2) extends upwards to the upper part of the needle tube assembly base (46), the safety sheath (3) is sleeved outside the needle seat (4), and a locking structure is formed between the inner wall of an inner cavity of the safety sheath (3) and the outer wall of the needle seat (4);

the safety sheath (3) is composed of an upper part and a lower part, the inner cavity of the safety sheath (3) is hollow, at least one positioning vertical bar (35) is distributed on the inner wall of the inner cavity of the lower part of the safety sheath (3), wherein the lower end of the positioning vertical bar (35) is deviated to one side to form a limiting step (351), and the limiting step (351) is distributed in a protruding mode on the inner wall of the inner cavity of the lower part of the safety sheath (3);

the safety sheath (3) is composed of an upper part and a lower part, the inner cavity of the safety sheath (3) is hollow, a limit convex strip (38) is arranged on the inner wall of the inner cavity of the upper part of the safety sheath (3), a convex point (381) is arranged on the limit convex strip (38), a plane (382) is formed at the lower end face of the limit convex strip (38), and the limit convex strip (38) and the axial direction of the safety sheath (3) are distributed in parallel;

the inner wall of the inner cavity of the safety sheath (3) is provided with a limit ring (34) which is distributed annularly, and the limit ring (34) is arranged in a convex shape on the inner wall of the inner cavity;

the top end of the upper part of the safety sheath (3) is provided with a needle penetrating hole (37);

at least one limit strip (45) is distributed on the outer wall of the assembly cavity (41), the limit strips (45) are distributed in a protruding mode on the outer wall of the assembly cavity (41), the limit strips (45) are matched with the positioning vertical strips (35), and a limit plane (451) matched with the limit steps (351) is formed at the lower end of the limit strips (45);

the needle tube assembling base is characterized in that a slideway (6) matched with the limit convex strips (38) is formed at the outer wall of the needle tube assembling base (46), a lower convex point (51) and an upper convex point (42) which are distributed up and down are arranged on the surface of the slideway (6), a convex transition inclined plane (47) is arranged at one side of the upper end of the slideway (6), a locking area (49) is formed at one side of the transition inclined plane (47), a convex blocking block (50) is formed at one side of the locking area, the locking area (49) is positioned between the transition inclined plane (47) and the blocking block (50), an anti-reversion platform (471) is formed at the inner side of the transition inclined plane (47), the anti-reversion platforms (471) at the two sides of the locking area (49) and the inner side walls of the blocking block (50) are flat walls, the inner side walls at the two sides are used for limiting the limit convex strips (38), a limit platform (52) is formed at the lower end of the locking area (49), the limit platform (52) is used for being matched with a plane (382) at the lower end of the limit convex strip (38), the slideway (6) and the locking area (49) are distributed alternately at the outer wall of the needle tube assembling base (46), and the locking area (6) is provided with a locking area between the locking area (49) and the needle tube alternately;

and a limiting block (48) protruding out of the outer wall of the needle tube assembly base (46) is arranged at the lower edge of the locking area (49), and the limiting block (48) is matched with the limiting ring (34) and used for blocking the limiting ring (34) from upwards displacing.

2. The safety insulin needle according to claim 1, wherein: the needle seat (4) is composed of a needle tube assembly base (46) positioned at the upper part and an assembly cavity (41) positioned at the lower part, the outer diameter of the needle tube assembly base (46) is smaller than that of the assembly cavity (41), an annular needle seat platform (43) is formed at the joint of the needle tube assembly base (46) and the assembly cavity (41), and an inner thread (53) is formed on the inner cavity wall of the assembly cavity (41).

3. The use method of the safe insulin needle is characterized in that: the using method comprises the following steps:

the safety insulin needle is screwed into the insulin pen clockwise, the internal thread (53) of the assembling cavity (41) of the needle seat (4) is matched with the external thread at the end part of the insulin pen, and in the clockwise rotation process, the limit step (351) is driven to gradually touch and finally mesh with the limit plane (451) so as to prevent the safety sheath from being pulled out when the sheath (3) is pulled out;

at the moment, the convex point (381) of the safety sheath is in interference fit with the lower convex point (51) of the needle seat, and the convex point (381) is positioned below the lower convex point (51) and used for preventing the safety sheath from upwards moving without any person;

after injection is completed, the safety sheath is rotated anticlockwise to be in place, so that the end face of the limit step (351) is separated from the limit plane (451);

then, the safety sheath is pulled upwards, the convex point (381) finally upwards passes through the upper convex point (42), at the moment, the upper convex point (42) forms temporary reverse limit on the convex point (381), and the limit ring (34) upwards abuts against the limit block (48) for limiting the upward displacement of the safety sheath;

at this time, the safety sheath is rotated clockwise, and the limit convex strips (38) slide into the locking areas (49) through the transition inclined planes (47) easily;

the two sides of the sliding locking area (49) are respectively provided with an anti-reverse platform (471) and a blocking block (50), and the anti-reverse platform (471) and the blocking block are respectively arranged on the two sidesUnder the limiting action of the block (50), the limit convex strips (38) cannot rotate in the clockwise direction and the anticlockwise direction;

on the axis direction, the plane (382) of the lower end face of the limit convex strip (38) is limited by the limit platform (52), the limit ring (34) is limited by the limit block (48), at this time, the safety sheath is limited in the forward and reverse rotation and up and down displacement, self-locking cannot be completed in a moving way, the needle tube is completely wrapped by the safety sheath, and the safety protection function is triggered.