CN219814899U - Locking assembly, locking mechanism and safety syringe with locking mechanism - Google Patents

Abstract

The utility model discloses a locking assembly, a locking mechanism and a safety syringe comprising the locking mechanism, wherein the locking assembly comprises a bracket, a sheath and a spring, the side surface of the bottom of the bracket is provided with a second bulge and a first bulge from bottom to top, the side surface of the upper end of the sheath is provided with a limiting part, a limiting opening and an elastic part from top to bottom in the axial direction, the lower half part of the bracket is arranged in the sheath in a matched manner and can axially move along the inside of the sheath, the spring is arranged in the sheath and sleeved outside the lower end of the bracket, the spring is used for jacking the spring of the bracket to abut against the first bulge and the sheath, the spring enables the second bulge to be buckled with the first bulge after moving to the limiting opening so as to lock the bracket and the sheath, so that a needle at the lower end of the syringe is always positioned in the sheath, the safety syringe comprises the syringe, a push rod and the locking mechanism, the whole structure of the locking assembly, the locking mechanism and the safety syringe is simple, the whole structure of the bracket and the sheath are difficult to loose after being locked, and good in locking effect.

Description

Locking assembly, locking mechanism and safety syringe with locking mechanism

Technical Field

The utility model belongs to the technical field of syringes, and particularly relates to a locking assembly, a locking mechanism and a safety syringe with the locking mechanism.

Background

Syringes are commonly used medical products, which require a targeted recovery or protective treatment of the needle after use to prevent injury to the individual by the needle. In order to avoid the injury of the needle, a syringe safety protection device and a locking mechanism are developed, the syringe safety protection device is triggered after the syringe is used, so that the needle is retracted into a sheath, and the positions of a bracket and the sheath are relatively fixed under the action of the locking mechanism, so that the needle after injection is not exposed outside any more. The existing locking mechanism has the defects of complex structure, more installation work parts and easy loosening and damage to cause the risk of exposing the needle again.

The inventor knows that there is the locking mechanism of improvement too in the relevant technical scheme, for example inner support and outer sleeve can set up the locking position of the backstop and slipping and lock the position in the circumference of the support separately while locking, for example the implementation form of the locking position can be set up a pair of backstop arms on the inner support, there are backstop positions on the outer sleeve at the same time, the backstop arm acts to realize the backstop; the slipping locking position can be provided with a pair of protruding blocks on the inner support, the protruding blocks and the retaining arms are alternately or alternately distributed, the outer sleeve is provided with a window which is axially distributed along the cylinder, and the protruding blocks are slidably clamped in the window, so that the slipping prevention of the support (namely the slipping is realized, the support is separated from the outer sleeve). However, according to the arrangement mode, the outer sleeve is required to be windowed, the manufacturing difficulty of the die is increased, the manufacturing wall thickness of the outer sleeve is thickened due to the fact that the outer sleeve is windowed, the bracket can be smoothly installed into the outer sleeve only by the aid of the tool clamp when the lug and the retaining arm are installed, and the installation work portion is increased. In addition, or in the related technical solutions known by the inventor, although the locking position is also provided, part of the locking position is very easy to loosen to cause slipping or retreating of the bracket or the jacket.

The term "lower or lower" in this disclosure means the end of the penetrating side pointing towards the front of the drug delivery device or the side or direction pointing towards the tip of the injection needle. The expression "above or upper" is contrary thereto.

It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the present disclosure and thus may include information that does not constitute prior art known to those of ordinary skill in the art.

Disclosure of Invention

The utility model aims to at least solve one of the technical problems in the prior art, and provides a locking assembly, a locking mechanism and a safety syringe with the locking mechanism.

The locking assembly of the present disclosure includes:

the side surface of the bracket is provided with a second bulge and a first bulge from top to bottom, and a channel or a containing space for installing the injector is arranged in the bracket;

the sheath is matched with the bracket main body, and the bracket main body can axially move in the sheath; the sheath is provided with an elastic piece and a limiting opening which is adjacent or not adjacent to the elastic piece and is used for locking the second bulge and/or the first bulge;

when the support and the sheath are far away from each other or only one side is far away from each other, the second bulge and/or the first bulge of the support sleeved in the sheath are completely or partially embedded into the limit opening, and the elastic piece is elastically abutted with the second bulge and/or the first bulge so as to realize locking between the support and the sheath.

The locking mechanism of the present disclosure includes:

the side surface of the bracket is provided with a second bulge and a first bulge from top to bottom, and a channel or a containing space for installing the injector is arranged in the bracket;

the protective sleeve is provided with an elastic piece and a limiting opening which is adjacent or not adjacent to the elastic piece and used for locking the second bulge and/or the first bulge, the bracket main body is mounted in a matched manner with the protective sleeve, and the bracket main body can axially move along the interior of the protective sleeve; the sheath and/or the bracket are/is also provided with a limiting piece which can enable the bracket to be clamped with and separated from the sheath;

the spring is sleeved between the bracket and the sheath, and two ends of the spring are respectively abutted against the first bulge and the sheath;

the limiting piece acts to separate the support from the sheath, when the support and the sheath are mutually far away or only one side is far away under the action of the spring, the second bulge and/or the first bulge of the support sleeved in the sheath are completely or partially embedded into the limiting opening, and the elastic piece is elastically abutted with the second bulge and/or the first bulge to realize locking between the support and the sheath.

In the present disclosure, the limiting member may be disposed on the support or the sheath, or the limiting member is disposed on the support and the sheath together, or the limiting member may have multiple manners of arrangement, for example, the limiting member adopts a snap-fit arrangement of convex-concave phase fastening, or other non-limiting multiple manners of implementation such as a snap-fit arrangement.

In the present disclosure, the limiting opening may be adjacent to the elastic member, or the limiting opening may be non-adjacent to the elastic member, so that the internal space and the mold opening cost may be saved when the limiting opening is adjacent to the elastic member.

In one embodiment of the locking mechanism of the present utility model, at least a part of the upper and lower end surfaces of the second protrusion is provided with a step or a groove, or the root of the second protrusion is in non-circular arc transition.

In one embodiment of the locking mechanism, the elastic piece elastically protrudes inwards, and the distal end of the elastic piece is abutted with the outer wall of the bracket passing through the cavity of the elastic piece or the non-circular arc root of the second bulge or the end face of the second bulge step or the groove.

In one embodiment of the locking mechanism of the utility model, the elastic piece forms an inclined part towards the inner part of the bracket or the protruding part of the core part of the bracket; when the second bulge is buckled with the limit opening or embedded or partially embedded, the distal end of the inclined part of the elastic piece is propped against the second bulge or a bracket area between the second bulge and the first bulge, and the first bulge is propped against the inclined part of the elastic piece, especially the proximal end of the inclined part of the elastic piece or the root of the inclined part.

In one embodiment of the locking mechanism of the present utility model, the back surface of the elastic member is further provided with a reinforcing rib which is flush with or does not protrude from the outer periphery of the sheath.

In one embodiment of the locking mechanism of the present utility model, a guide channel for moving the first protrusion and the second protrusion is provided on the inner wall of the sheath.

In one embodiment of the locking mechanism, the limiting piece protrudes outwards or inwards in the direction away from the core part of the sheath, and the bracket is provided with a buckling part which is opposite to the protruding or inwards concave direction of the limiting piece.

In one embodiment of the locking mechanism, the locking mechanism further comprises a bottom cover, the lower end of the sheath is integrally or detachably connected with the bottom cover, and a through hole for a needle head of the syringe to move through is formed in the middle of the bottom cover.

The safety syringe comprises the locking mechanism, the syringe and the push rod which can be axially and slidably loaded in the syringe barrel, the syringe can be loaded and limited in the bracket, the push rod can axially move along the inside of the syringe barrel, and when the push rod is pushed downwards to prop against the inner wall of the lower end of the syringe barrel, the limiting piece is separated from the bracket, so that the spring elastically resets and lifts the bracket;

in one embodiment of the safety syringe, the safety syringe further comprises a trigger piece, wherein the trigger piece is movably sleeved at the sleeved joint part of the bracket and the sheath; when the push rod axially moves along the inside of the barrel of the injector to prop against the inner wall of the lower end of the barrel of the injector, the push rod triggers the trigger piece to move downwards so that the limiting piece is separated from the bracket, and the spring resets and lifts the bracket.

In one embodiment of the safety syringe of the present utility model, the push rod has a pressing portion at an upper end thereof.

The locking assembly and the locking mechanism have the beneficial effects that:

according to the locking assembly and the locking mechanism disclosed by the utility model, the elastic piece and the limit opening are arranged at the upper end of the sheath, the first bulge and the second bulge are arranged on the bracket, the spring is arranged between the bracket and the sheath, the spring is used for jacking the bracket to enable the second bulge to be buckled or embedded or partially embedded after moving to the limit opening, so that the locking between the bracket and the sheath is realized, the buckling or embedding between the second bulge and the limit opening is relatively firm, the looseness is not easy, and the locking structure is relatively simple.

The locking assembly and the locking mechanism disclosed by the utility model unify locking backings into the same direction and the same side, so that the die opening cost and the tooling fixture process for arranging the locking backings at different positions are reduced, two bulges are arranged on the bracket, and the first bulge can be used for abutting against the spring so that the spring can be enclosed in the sheath, and the winding risk caused by exposing the spring in the prior art during release is different from that caused by exposing the spring in the prior art.

The safety syringe disclosed by the utility model can ensure that the needle at the lower end of the syringe is always positioned in the sheath by arranging the locking mechanism.

The features and advantages of the present utility model will be described in detail by way of example with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic view showing a locked state structure in which a stent and a sheath according to an embodiment of the present utility model are disengaged.

Fig. 2 is a front cross-sectional view of fig. 1 in accordance with one embodiment of the present utility model.

Fig. 3 is a schematic diagram of an initial state structure of an embodiment of the present utility model.

Fig. 4 is a front cross-sectional view of fig. 3 in accordance with one embodiment of the present utility model.

Fig. 5 is a schematic view of a jacket structure according to an embodiment of the present utility model.

Fig. 6 is a schematic view of a stent structure according to an embodiment of the present utility model.

Fig. 7 is a schematic view of a buckle structure according to an embodiment of the present utility model.

Fig. 8 is a schematic structural view of another embodiment of the present utility model.

Fig. 9 is a cross-sectional view taken along the B-B plane in fig. 8 of another embodiment of the present utility model.

Fig. 10 is a schematic view showing a locked state structure in which a stent and a sheath according to another embodiment of the present utility model are disengaged.

In the figure: 1-injection assembly, 2-support, 3-sheath, 4-spring, 5-trigger, 11-push rod, 12-syringe, 21-first boss, 22-second boss, 31-bottom cap, 32-stopper, 33-elastic member, 34-stopper.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. It will be apparent that the described embodiments are some, but not all, embodiments of the utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. In the description of the present utility model, it should be noted that, the azimuth or positional relationship indicated by the terms "inner", "outer", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship that is commonly put in use of the product of this application, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed", "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

The present utility model will be described in detail with reference to fig. 1 to 10 of the accompanying drawings.

Embodiment 1 referring to fig. 1, 2, 3, 4 and 5, this embodiment provides a locking assembly comprising:

a bracket 2, wherein a second protrusion 22 and a first protrusion 21 are arranged on the side surface of the bracket 2 from top to bottom, and a channel or accommodating space for installing the syringe 12 is arranged inside the bracket 2;

a sheath 3, the sheath 3 is mounted in cooperation with the body of the bracket 2 and the body of the bracket 2 can axially move inside the sheath 3; the sheath 3 is provided with an elastic piece 33 and a limit opening 34 which is adjacent to or not adjacent to the elastic piece 33 and is used for locking the second bulge 22 and/or the first bulge 21;

when the bracket 2 and the sheath 3 are far away from each other or only one of them is far away from each other, the second protrusion 22 and/or the first protrusion 21 of the bracket 2 sleeved in the sheath 3 are fully or partially embedded into the limit opening 34, and the elastic piece 33 is elastically abutted with the second protrusion 22 and/or the first protrusion 21 so as to realize locking between the bracket 2 and the sheath 3.

The embodiment also provides a locking mechanism, including:

the side surface of the bracket 2 is provided with a second bulge 22 and a first bulge 21 from top to bottom, and a channel or a containing space for installing the injector is arranged in the bracket; in practical use, the first protrusion 21 and the second protrusion 22 may be symmetrically disposed on the left and right sides of the lower portion of the support 2, or disposed in n directions of the lower side of the support 2 according to an included angle of 360/n, and the width and thickness of the second protrusion 22 and the first protrusion 21 are not limited, and may be the same or different, and the thickness may be the same or different.

The jacket 3, the upper end side of the jacket 3 is provided with a limiting piece 32 and an elastic piece 33 from top to bottom along the axial direction, a limiting opening 34 is reserved between the limiting piece 32 and the elastic piece 33, and part of the bracket 2 is mounted inside the jacket 3 in a matched manner and can axially move along the inside of the jacket 3;

the sheath 3 is provided with an elastic piece 33 and a limiting opening 34 adjacent or not adjacent to the elastic piece 33, the limiting opening 34 is used for locking the second bulge 22 and/or the first bulge 21, the bracket main body is matched with the sheath 3 and can axially move along the interior of the sheath 3; the limit opening 34 is adjacent to the elastic piece 33, so that the processing advantage and the processing cost advantage are better; when the limiting opening 34 is not adjacent to the elastic piece 33, the effect of the scheme can be completely realized. In actual use, the number of the elastic pieces 33 may be identical to that of the limiting openings 34, or may be inconsistent, so that the effect of the scheme can be achieved, for example, when the limiting openings 34 are provided in a plurality of ways, for example, when four limiting openings 34 are provided, the number of the elastic pieces 33 may be less than four, for example, two in opposite directions are provided, and the effect of the scheme can also be achieved; if in a certain embodiment, the first protrusion 21 and the second protrusion 22 are symmetrically disposed on the left and right sides of the lower portion of the bracket 2, and the limiting opening 34 may be disposed according to the corresponding position; or the first protrusion 21 and the second protrusion 22 are arranged in n directions of the lower side surface of the bracket 2 according to 360/n included angle, and the limit opening 34 can be correspondingly arranged.

The spring 4 is sleeved between the bracket 2 and the sheath 3, specifically, the spring 4 can be installed in the sheath 3 and sleeved outside the lower end of the bracket 2, and two ends of the spring 4 respectively abut against the first bulge 21 and the sheath 3;

the sheath 3 and/or the bracket 2 are also provided with a limiting piece 32, and the limiting piece 32 can enable the bracket 2 to be clamped with or separated from the sheath 3; when the limiting piece 32 acts to enable the support 2 and the sheath 3 not to be clamped any more, the spring 4 lifts the support 2 or the spring 4 lifts to enable the support 2 and the sheath 3 to move backwards, so that the second bulge 22 moves, the elastic piece 33 can be stretched in the moving process of the second bulge 22, the elastic piece 33 is enabled to elastically deform along the radial direction of the sheath 3 until the second bulge 22 is buckled or embedded with the limiting opening 34, and meanwhile the elastic piece 33 is clamped into the support 2 area between the second bulge 22 and the first bulge 21, so that locking between the support 2 and the sheath 3 is achieved.

In this embodiment, an opening or a window is provided at a corresponding position of the upper end of the sheath 3, and the limiting member 32 and the elastic member 33 are disposed in the opening or the window. Of course, the limiting member 32 and the elastic member 33 may be provided on the sheath 3 in other openings or non-openings, or in a windowed or non-windowed manner.

This solution can also be implemented when the second protrusions 22 and/or the first protrusions 21 are in close proximity to each other, or are integrally provided.

The inner wall of the sheath 3 is provided with guide channels for the movement of the first and second projections 21, 22, which are designed to facilitate the assembly between the sheath 3 and the stent 2.

In this embodiment of the disclosure, as shown in the accompanying drawings, the limiting members 32 are respectively disposed at corresponding positions of the support 2 and the sheath 3 in a buckling manner, and as shown in the accompanying drawings, the limiting openings 32 are disposed adjacent to the elastic members 33, so as to facilitate mold opening.

In the present disclosure, at least a part of the upper and lower end surfaces of the second protrusion 22 is provided with a step or a groove, or the root of the second protrusion 22 is in non-circular arc transition, or the included angle between the upper and lower end surfaces of the second protrusion 22 and the outer surface of the bracket 2 is an acute angle or a right angle; as shown in the drawing, in this embodiment, the included angle between the upper and lower end surfaces of the second protrusion 22 and the outer surface of the bracket 2 is a right angle; the elastic member 33 in the present disclosure protrudes elastically inward, and the distal end of the elastic member 33 abuts against the non-circular root of the second protrusion 22.

The elastic member 33 radially protrudes out of the bracket 2, or a portion of the elastic member 33 protruding or protruding toward the core of the bracket 2 forms an inclined portion; when the second protrusion 22 is buckled or embedded or partially embedded with the limiting opening 34, the distal end of the inclined part of the elastic piece 33 abuts against the second protrusion 22 or the bracket 2 area between the second protrusion 22 and the first protrusion 21, and the first protrusion 21 abuts against the inclined part of the elastic piece 33.

The back of the elastic member 33 is also provided with a reinforcing rib which is flush with the outer periphery of the sheath 3 or does not protrude beyond the outer periphery of the sheath 3. See in particular the accompanying drawings.

The inner wall of the sheath 3 is provided with guide channels for the movement of the first and second projections 21, 22 in order to facilitate the mounting of the stent 2 inside the sheath 3, which guide channels are not shown in the drawing.

In this embodiment, the limiting member 32 protrudes outwards or is recessed inwards in a direction away from the core of the sheath, and the bracket 2 is provided with a buckling part opposite to the protruding or recessed direction of the limiting member 32; the more preferable buckling surface of the buckling part of the limiting piece 32 and the bracket 2 is obliquely arranged, so that the buckling effect is better and the slipping is less easy; of course, other engagement manners are also possible, such as a manner in which the engaging portion of the bracket 2 protrudes radially outward when the stopper 32 protrudes radially inward.

The lower end of the sheath 3 is integrally connected with the bottom cover 31 or detachably connected with the bottom cover 31, wherein the detachable connection mode comprises various modes including but not limited to buckling or screwing, and the middle part of the bottom cover 31 is provided with a through hole for the needle of the syringe 12 to pass through.

When the limiting piece 32 is connected with the support 2, the spring 4 is in a compressed state, and when the push rod 11 pushes downwards until the limiting piece 32 is separated from the support 2 when the push rod abuts against the inner wall of the lower end of the barrel of the syringe 12, the spring 4 elastically resets and lifts the support 2.

The embodiment also discloses a safety syringe, which comprises an injection assembly 1 and the locking mechanism, wherein the injection assembly 1 comprises a syringe 12 and a push rod 11, the syringe 12 comprises a barrel and a needle head arranged at the bottom of the barrel, and a needle cap is arranged at the needle head or not; the injector 12 is arranged in a channel of the bracket 2, the push rod 11 is arranged in a cylinder of the injector 12 and can axially move along the inside of the cylinder of the injector 12, and when the push rod 11 is pushed downwards to prop against the inner wall of the lower end of the cylinder of the injector 12, the limiting piece 33 is separated from the bracket 2 so that the spring 4 elastically resets and lifts the bracket 2; further, the upper end of the push rod 11 is also provided with a pressing portion.

Referring to fig. 4, 6 and 7, in the present embodiment, the limiting member 32 protrudes outwards towards the direction away from the core of the sheath and forms a hook, the bracket 2 is provided with a concave groove, the hook and the slot are fastened when the limiting member 33 is installed on the bracket 2, the bracket 2 is provided with a containing slot 23, the trigger member 5 is installed in the containing slot 23, the lower end of the trigger member 5 corresponds to the fastening position of the hook and the slot, and when the push rod 11 moves downwards, the pressing portion at the top of the push rod 11 pushes the trigger member 5 to push down so that the hook is separated from the slot, and the sheath 3 is separated from the bracket 2.

The working process of the utility model comprises the following steps:

in the working process of the locking mechanism, in the initial state, the needle head of the injector 12 is positioned at the outer side of the sheath 3, the needle cap is sleeved at the outer side of the needle head, at the moment, the clamping hooks of the limiting parts 32 at the two sides of the upper end of the sheath 3 are buckled with the clamping grooves on the support 2, the support 2 tightly presses the spring 4 in the sheath 3, when the injector is needed to be used, the push rod 11 is pressed by hands, the push rod 11 is pushed to a certain distance to push the trigger piece 5 sleeved on the support 3 downwards, so that the trigger piece 5 pushes the clamping hooks of the limiting parts 32 away from the clamping grooves to separate the clamping hooks from each other, the support 2 moves upwards under the elastic action of the spring 4 until the second protrusions 22 are buckled with the corresponding limiting openings 34 on the sheath 3, and the locking of the sheath 3 and the support 2 is completed, and the needle head is retracted into the sheath 3.

Example 2

Referring to fig. 8 to 10, the present embodiment is similar to embodiment 1 except that the longitudinal section of the second protrusion 22 is triangular.

In the present utility model, the operation of the trigger 5 is just one way to disengage the holder 2 from the sheath 3, and the engagement and disengagement of the holder 2 and the sheath 3 may take many forms.

In the present utility model, the number, shape and spacing distance of the first protrusions 21 and the second protrusions 22 are not limited, and it is only required that the elastic member 33 is clamped in the area between the first protrusions 21 and the second protrusions 22 are clamped in the limiting opening 34 after the spring 4 lifts the bracket 2.

The foregoing description is only of the preferred embodiments of the present utility model, and is not intended to limit the scope of the utility model, but rather is intended to cover all equivalent structures as modifications within the scope of the utility model, either directly or indirectly, as may be contemplated by the present utility model.

Claims (10)

1. A locking assembly, comprising:

the syringe comprises a bracket (2), wherein a second bulge (22) and a first bulge (21) are arranged on the side surface of the bracket (2) from top to bottom, and a channel or a containing space for installing a syringe (12) is arranged inside the bracket (2);

the sheath (3) is matched with the main body of the bracket (2), and the main body of the bracket (2) can axially move inside the sheath (3); an elastic piece (33) and a limit opening (34) which is adjacent to or not adjacent to the elastic piece (33) and used for locking the second bulge (22) and/or the first bulge (21) are arranged on the sheath (3);

when the support (2) and the sheath (3) are far away from each other or only one of them is far away from each other, the second bulge (22) and/or the first bulge (21) of the support (2) sleeved in the sheath (3) are completely or partially embedded into the limit opening (34), and the elastic piece (33) is elastically abutted with the second bulge (22) and/or the first bulge (21) so as to realize locking between the support (2) and the sheath (3).

2. A locking mechanism comprising the locking assembly of claim 1, wherein:

a limiting piece (32) which can enable the bracket (2) to be clamped with and separated from the sheath (3) is further arranged on the sheath (3) or the bracket (2);

the novel anti-theft device is characterized by further comprising a spring (4), wherein the spring (4) is sleeved between the bracket (2) and the sheath (3), and two ends of the spring (4) are respectively abutted against the first bulge (21) and the sheath (3);

the limiting piece (32) acts to enable the support (2) to be separated from the sheath (3), when the support (2) and the sheath (3) are far away from each other or only one side of the support is far away from each other under the action of the spring (4), the second bulge (22) and/or the first bulge (21) of the support (2) sleeved in the sheath (3) are completely or partially embedded into the limiting opening (34), and the elastic piece (33) is elastically abutted with the second bulge (22) and/or the first bulge (21) to achieve locking between the support (2) and the sheath (3).

3. The locking mechanism of claim 2, wherein: at least one part of the upper end face and the lower end face of the second bulge (22) is provided with a step or a groove, or the root of the second bulge (22) is in non-circular arc transition.

4. The locking mechanism of claim 3, wherein: the elastic piece (33) is elastically inwards protruded, and the distal end of the elastic piece (33) is abutted with the non-circular root of the outer wall of the bracket (2) or the step or the groove end surface of the second bulge (22) passing through the cavity of the elastic piece.

5. The locking mechanism of claim 2, wherein: the part of the elastic piece (33) protruding towards the inside of the bracket (2) forms an inclined part; when the second bulge (22) is buckled with the limit opening (34) or embedded or partially embedded, the distal end of the inclined part of the elastic piece (33) is propped against the second bulge or the bracket (2) area between the second bulge (22) and the first bulge (21), and the first bulge (21) is propped against the proximal end of the inclined part of the elastic piece (33) or the root of the inclined part; the first protrusion (21) abuts against the inclined portion of the elastic member (33).

6. The locking mechanism of claim 2, wherein: the inner wall of the sheath (3) is provided with a guide channel for the movement of the first bulge (21) and the second bulge (22).

7. The locking mechanism of claim 2, wherein: the limiting piece (32) protrudes outwards or inwards in the direction away from the core part of the sheath (3), and the bracket (2) is provided with a buckling part which is opposite to the protruding or inwards concave direction of the limiting piece (32).

8. The locking mechanism of claim 2, wherein: the syringe is characterized by further comprising a bottom cover (31), wherein the lower end of the sheath (3) is integrally or detachably connected with the bottom cover (31), and a through hole for a needle head of the syringe (12) to pass through is formed in the middle of the bottom cover (31).

9. A safety syringe comprising a syringe (12) which can be loaded in a bracket and a push rod (11) which can be axially and slidably loaded in a barrel of the syringe (12), characterized in that the safety syringe further comprises a locking mechanism as claimed in any one of claims 2 to 8, wherein the push rod (11) can axially move along the inside of the barrel of the syringe (12), and when the push rod (11) moves downwards to abut against the inner wall of the lower end of the barrel of the syringe (12), a limiting piece (32) is separated from the bracket (2) so that the spring (4) elastically resets and lifts the bracket (2).

10. The safety syringe of claim 9, wherein: the device also comprises a trigger piece (5), wherein the trigger piece (5) is movably sleeved at the sleeved joint part of the bracket (2) and the sheath (3); when the push rod (11) axially moves to be abutted against the lower end of the inner wall of the cylinder of the injector (12) along the inner part of the cylinder of the injector (12), the push rod (11) triggers the trigger piece (5) to move downwards so that the limiting piece (32) is separated from the bracket (2).