CN212914096U

CN212914096U - Automatic injector

Info

Publication number: CN212914096U
Application number: CN202022322096.7U
Authority: CN
Inventors: 倪世利; 孙小峰; 徐千贺; 李文政; 李志飞
Original assignee: Shandong Weigao Prefills Pharmaceutical Packaging Co Ltd
Current assignee: Shandong Weigao Prefills Pharmaceutical Packaging Co Ltd
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2021-04-09
Anticipated expiration: 2030-10-16

Abstract

The utility model discloses an automatic injector, include: the device comprises a shell, a needle protecting cover, a push rod, a sound tube, an inner tube, a release ring, a driving elastic element and a resetting elastic element. When the automatic injection syringe is used, the syringe is fixed in the shell, the needle head extends out of the front end of the shell, the needle shield can stretch and be connected to the shell, the needle shield can push the release ring to slide towards the rear end of the shell, after the release ring moves towards the rear end, the first clamping of the inner tube releases clamping and limiting on the push rod, and the push rod pushes the piston to inject liquid in the syringe to a part of a body needing injection under the action of the driving elastic piece, so that the aim of automatic injection is fulfilled. After the injection is finished, the sounding cylinder is separated from the limit of the inner tube and slides towards the rear end of the shell, so that a signal of finishing the injection is sent. The automatic injection syringe that this scheme provided can realize the automatic injection function of embedment cylinder in advance through eight spare parts, and for prior art, this scheme simple structure, part figure are few, the mechanism action principle is simple, the reliability is high.

Description

Automatic injector

Technical Field

The utility model relates to the technical field of medical equipment, especially, relate to an automatic injector.

Background

The automatic injector is a medical instrument which can automatically inject liquid medicine in a pre-filled injection cylinder into a patient body, and can meet the self-administration requirement of a user. The automatic injector is a medical apparatus of a patient self-use type, and because a general patient is not a professional medical worker, the automatic injector is generally required to have the characteristics of simplicity, easiness in use, high reliability, comfortable experience and the like, and can send out a prompt signal to help a user to confirm that the injection is finished after the injection is finished.

Prior automatic injectors, when used, typically achieve penetration and injection by simply pressing the forward end of the barrel against the site to be injected and requiring manual movement of the rearward end of the barrel. When the front end of the automatic injector is positioned at the injection site of a patient, the starting part on the automatic injector is pressed to activate the automatic injector, the needle can rapidly puncture the skin, and the medicine is automatically injected through the needle.

However, the existing automatic injector has a complex structure, a large number of internal parts, and is prone to product function failure, so that the product reliability is poor, and the product processing and assembling procedures are multiple, so that the product cost is high.

Therefore, how to improve the reliability of the automatic injector is a technical problem that needs to be solved by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides an automatic injector, which has a simple structure, high reliability, easy assembly and low cost.

In order to achieve the above object, the present invention provides the following technical solutions:

an autoinjector comprising: the device comprises a shell, a needle protecting cover, a push rod, a sound tube, an inner tube, a release ring, a driving elastic element and a resetting elastic element;

a needle cylinder fixing structure for fixing the needle cylinder is arranged in the shell, and an opening for extending the needle head is formed in the front end of the shell;

the release ring and the needle shield are sequentially arranged in the shell in a sliding manner from the rear end to the front end, the needle shield can extend out of the front end of the shell and can slide towards the rear end relative to the shell and push the release ring, and the reset elastic piece acts on the release ring and drives the release ring to push the needle shield to slide towards the front end of the shell; the shell is provided with a needle shield limiting structure for limiting the forward sliding distance of the needle shield relative to the shell;

the push rod is arranged in the shell in an axial sliding mode, the front end of the push rod is used for pushing a piston in the needle cylinder, the driving elastic piece acts on the push rod and drives the push rod to slide towards the front end of the needle cylinder, and a push rod limiting structure is arranged on the periphery of the push rod;

the sounding cylinder is sleeved on the periphery of the push rod in an axial sliding manner, the driving elastic piece acts on the sounding cylinder and drives the sounding cylinder to slide towards the rear end of the shell, the sounding cylinder is provided with a push rod limiting and matching structure, and a sounding cylinder limiting structure is arranged between the sounding cylinder and the inner tube;

the inner tube is fixed in the shell and sleeved on the periphery of the sounding barrel, the release ring is sleeved on the periphery of the inner tube in a sliding mode, the inner tube is provided with a first clamping clip capable of elastically moving along the radial direction, and the first clamping clip is deflected outwards along the radial direction under the action of the elasticity of the first clamping clip;

first clamping can radially inwards squint and pass through under the limiting displacement of the inner wall of release ring the spacing cooperation structure of push rod with the mutual joint of push rod limiting structure is spacing, it can to play a section of thick bamboo limiting structure limit under the supporting action of the outer wall of push rod play a section of thick bamboo with the relative slip of inner tube, the push rod can break away from behind the preset distance of sliding to the front end and to play a section of thick bamboo limiting structure's support.

Preferably, the rear end of the shell is provided with a signal structure for limiting impact with the sound tube.

Preferably, the signal structure is an end plate fixed to a rear end of the housing.

Optionally, the needle protection device further comprises a needle cap which is detachably connected with the front end of the needle protection cover.

Preferably, the rear end of the needle cap is provided with a hook claw which is used for being clamped with the rear end of the needle sheath, and the hook claw can exert a pulling force action towards the front end direction on the needle sheath.

Preferably, an anti-falling concave-convex matching structure is arranged between the inner ring of the needle cap and the circumferential direction of the needle shield cover.

Preferably, a needle cap limiting structure for limiting the needle cap to move towards the rear end relative to the housing is arranged between the housing and the needle cap.

Preferably, the syringe fixing structure is a syringe fixing cylinder fixed on the inner side of the shell, and a syringe clamping jaw used for being in limit fit with a front end shoulder of the syringe is arranged at the front end of the syringe fixing cylinder.

Preferably, the rear end of the needle cylinder fixing cylinder is provided with a support body which is used for being in limit fit with the rear end flange of the needle cylinder, and an elastic cushion block is arranged between the support body and the front end face of the rear end flange of the needle cylinder.

Preferably, a front end of the inner tube abuts against a rear end surface of a rear end flange of the cylinder, and a rear end of the inner tube abuts against a rear end of the housing.

Preferably, the rear end of the housing is provided with an annular protrusion coaxially matched with the rear end of the inner tube, and a rotation limiting structure for preventing the inner tube from rotating is arranged between the side wall of the housing and the inner tube.

Preferably, the push rod limiting and matching structure is an audio tube avoiding notch formed in the side wall of the audio tube, and the audio tube avoiding notch is arranged along the axial extension of the audio tube.

Preferably, sound a section of thick bamboo limit structure including set up in sound a section of thick bamboo lug and seting up in sound on the inner tube be used for with sound the spacing joint in section of thick bamboo lug inner tube card hole.

Preferably, the inner tube is provided with an inner tube avoiding slotted hole extending along the axial direction, the release ring is provided with a second clamping matched with the inner tube avoiding slotted hole in a sliding mode, the second clamping can interact with the sounding cylinder, and the outer side of the sounding cylinder is provided with a clamping limiting structure used for limiting the second clamping to move towards the rear end direction of the shell.

Preferably, the push rod is a hollow rod-shaped structure, the driving elastic part is a push rod spring arranged inside the push rod, and the push rod spring is arranged between the front end of the push rod and the rear end of the sound tube in a compression mode.

Preferably, a spring guide rod is slidably arranged inside the push rod, and the push rod spring is sleeved on the periphery of the spring guide rod.

Preferably, the return elastic member is a return spring which is disposed in compression between the release ring and the housing.

Preferably, the housing includes a front housing and a rear housing, the front housing being connected to a front end of the rear housing.

Preferably, the housing and the needle shield are each provided with an axially extending viewing window.

Preferably, the needle shield limiting structure comprises a first limiting step arranged on the inner wall of the housing and a second limiting step arranged on the outer wall of the needle shield.

The utility model provides an automatic injector's theory of operation as follows:

the automatic injector has a pre-filled and sealed syringe installed inside the casing, needle protected by needle sheath and capable of protecting the needle and the needle sheath.

When injection is needed, the needle sheath for protecting the needle head is taken down, then the shell is held by hands, the front end of the shell is aligned to the part of the body needing injection, the needle protecting cover is aligned to the part needing injection and is pressed by force, at the moment, the needle protecting cover overcomes the elasticity of the resetting elastic piece and drives the release ring to move towards the rear end relative to the shell together, and therefore the needle head can penetrate into the part needing injection. In the process that the release ring moves towards the rear end of the shell, the first clamping of the inner tube is separated from the limit of the inner wall of the release ring, so that the clamping of the push rod is limited, the push rod slides towards the front end of the needle cylinder under the action of the driving elastic part, and liquid in the needle cylinder is injected into a body through the needle head through the piston, so that automatic injection is realized.

In the push rod injection process, the outer wall of the push rod can provide a continuous supporting effect on the sound tube limiting structure, so that the relative fixation of the sound tube and the inner tube is ensured; and after the push rod slides for a preset distance, namely, after the push rod finishes injecting the liquid with the preset amount in the needle cylinder, the sounding cylinder limiting structure is separated from the support of the outer wall of the push rod, so that the sounding cylinder can slide towards the rear end of the shell under the action of the driving elastic part. The sound tube can prompt the user that the injection is finished through various modes such as sound production, light emission, impact vibration and the like in the sliding process or after the sound tube slides for a certain distance. The user only needs to pull the needle out of the body to complete the whole injection process.

The utility model discloses the scheme has following beneficial effect:

1) the automatic injector provided by the scheme can realize the automatic injection function of the pre-filled and sealed needle cylinder through eight parts, and compared with the automatic injector in the prior art, the automatic injector has the advantages of simple structure and less parts;

2) the scheme can realize the function of automatic injection by a pressing mode, and has simple mechanism action principle and high reliability;

3) the product is easy to assemble, the manual assembly cost is reduced, and the product yield is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic view of the overall external structure of an automatic injector according to an embodiment of the present invention;

fig. 2 is a schematic view of a first internal structure of an automatic injector according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a second internal structure of the automatic injector according to an embodiment of the present invention;

FIG. 4 is a schematic view of the position relationship between the needle cap, the needle cylinder and the needle sheath according to the embodiment of the present invention;

fig. 5 is a schematic structural view of a needle cap according to an embodiment of the present invention;

fig. 6 is a schematic diagram of the assembly of the needle cap and the front housing;

fig. 7 is a schematic axial limiting view of a needle shield and a front housing according to an embodiment of the present invention;

fig. 8 is a schematic axial limiting diagram of a needle shield and a needle cap according to an embodiment of the present invention;

fig. 9 is a schematic view of the positioning of the front housing and the syringe shoulder in an embodiment of the present invention;

fig. 10 is a schematic view illustrating a positional relationship between a cushion block and a rear flange according to an embodiment of the present invention;

fig. 11 is a schematic diagram of a position relationship between a cushion block and a front housing according to an embodiment of the present invention;

fig. 12 is a schematic view of an external structure of a push rod according to an embodiment of the present invention;

fig. 13 is a schematic view of a hollow structure of a push rod according to an embodiment of the present invention;

fig. 14 is a schematic view of an assembly structure of the push rod and the push rod spring according to an embodiment of the present invention;

fig. 15 is a schematic view of an external structure of a sound tube according to an embodiment of the present invention;

fig. 16 is a schematic view of an internal structure of the sound tube and the push rod assembly according to the embodiment of the present invention;

fig. 17 is a schematic view of an external structure of the sound tube and the push rod assembly according to the embodiment of the present invention;

fig. 18 is a schematic view of the outer structure of the inner tube according to the embodiment of the present invention;

fig. 19 is a schematic view of an assembly structure of the inner tube, the sound tube and the push rod according to an embodiment of the present invention;

FIG. 20 is a schematic view of an inner structure of the inner tube, the sound tube and the push rod assembly according to an embodiment of the present invention;

fig. 21 is a schematic view illustrating a positional relationship between an inner tube and a rear flange according to an embodiment of the present invention;

fig. 22 is a schematic view of the axial position limitation of the inner tube and the push rod in the embodiment of the present invention;

fig. 23 is a schematic view of the outer structure of a release ring according to an embodiment of the present invention;

fig. 24 is a schematic view of the inner structure of the release ring assembled with the inner tube and the push rod according to the embodiment of the present invention;

fig. 25 is an external view of the release ring assembled with the inner tube and the push rod according to the embodiment of the present invention;

fig. 26 is a schematic view of the release ring and the sounding barrel axial limit in the embodiment of the present invention;

fig. 27 is a schematic structural view of a push rod spring according to an embodiment of the present invention;

fig. 28 is a schematic structural view of a spring guide according to an embodiment of the present invention;

fig. 29 is a schematic structural view of a rear housing according to an embodiment of the present invention;

fig. 30 is a schematic view of an assembly structure of the rear housing and the inner tube according to an embodiment of the present invention;

fig. 31 is a schematic structural view of a return spring according to an embodiment of the present invention;

fig. 32 is a schematic view of an automatic injector according to an embodiment of the present invention after removal of the needle cap;

FIG. 33 is a schematic view of the needle shield in an embodiment of the invention shown after retraction to expose the needle;

fig. 34 is a schematic view of a first longitudinal section of an autoinjector in accordance with an embodiment of the present invention during use;

fig. 35 is a second longitudinal cross-sectional view of an automatic injector in accordance with an embodiment of the present invention during use;

fig. 36 is a third schematic longitudinal cross-sectional view of an autoinjector according to an embodiment of the present invention during use;

fig. 37 is a fourth schematic longitudinal cross-sectional view of an autoinjector embodiment of the present invention during use;

fig. 38 is a fifth longitudinal cross-sectional view of an autoinjector embodiment of the present invention during use;

fig. 39 is a sixth schematic longitudinal cross-sectional view of an autoinjector according to an embodiment of the present invention during use;

fig. 40 is a schematic longitudinal cross-sectional view of an automatic injector after use in accordance with an embodiment of the present invention;

fig. 41 is an enlarged partial longitudinal cross-sectional view of an automatic injector after use in accordance with an embodiment of the present invention.

The meaning of the individual reference numerals in fig. 1 to 41 is:

1-shell, 11-front shell, 12-rear shell, 13-observation window, 110-syringe fixing cylinder, 111-first limit step, 112-syringe clamping jaw, 113-elastic cushion block, 114-support body, 120-end plate, 121-annular bulge, 122-inner tube anti-rotation limit groove and 123-rear shell mounting ring groove;

14-needle cap, 141-needle sheath mounting hole, 142-needle cap anti-drop limiting part, 143-hook claw, 144-needle cap limiting structure and 145-needle cap inner cylinder;

2-a needle shield cover, 21-a needle shield cover anti-falling limiting part, 22-a second limiting step and 23-a needle shield cover inner ring bulge;

3-push rod, 31-push rod ring groove;

4-sound cylinder, 41-sound cylinder bump, 42-sound cylinder avoiding notch, 43-clamp limiting opening and 44-clamp avoiding opening;

5-inner tube, 51-inner tube anti-rotation bulge, 52-inner tube front end, 53-inner tube clamping hole, 54-inner tube avoiding slotted hole and 55-first clamp;

6-a release ring, 61-a rear end flange of the release ring, 62-a second clamp;

7-push rod spring, 71-spring guide rod and 711-guide rod end;

8-a return spring;

9-syringe, 91-needle, 92-needle sheath, 93-piston, 94-rear flange.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1 to 41, the present invention provides an automatic injector, including: the device comprises a shell 1, a needle protecting cover 2, a push rod 3, a sound tube 4, an inner tube 5, a release ring 6, a driving elastic element and a resetting elastic element. The automatic injector may be shipped as an injector including a prefilled syringe by previously assembling the prefilled syringe 9 into the housing 1 at the time of assembly.

The housing 1 is a main supporting and protecting component of the entire automatic injector, and is used for fixing components such as the needle cylinder 9 and the inner tube 5, and providing a space for installation and action for other components, the housing 1 may be designed into a hollow cylindrical structure as shown in fig. 1, of course, an ergonomic adapting structure which is more convenient for a human hand to hold may also be designed outside the housing 1, and a user holds the housing 1 to perform a pressing operation during injection. A syringe fixing structure for fixing the syringe 9 is arranged in the shell 1, and the front end of the shell 1 is provided with an opening for the needle head 91 to extend out; the inner side of the shell 1 is sequentially provided with a release ring 6 and a needle shield 2 in a sliding manner from the rear end to the front end, the needle shield 2 can extend out of the front end of the shell 1 and can slide towards the rear end relative to the shell 1 and push the release ring 6, and the reset elastic piece acts on the release ring 6 and drives the release ring 6 to push the needle shield 2 to slide towards the front end of the shell 1; the housing 1 is provided with a shield stop for limiting the forward sliding distance of the shield 2 relative to the housing 1. Preferably, the needle shield retainer comprises a first retaining step 111 disposed on the inner wall of the housing 1 and a second retaining step 22 disposed on the outer wall of the needle shield 2, as shown in fig. 7, and the needle shield retainer is used for preventing the needle shield 2 from being removed from the housing 1. Certainly, the needle shield limiting structure can also be designed into other shape structures, for example, the inner wall of the front section part of the shell 1 is designed into a tapered inner wall which is gradually reduced from the rear end to the front end, and the outer wall of the needle shield 2 is designed into a tapered outer wall matched with the outer wall, so that the needle shield 2 is prevented from being separated; or a limit stop pin and other structures are designed between the needle shield cover 2 and the inner wall of the shell 1, and the limit function can be achieved.

It should be noted that the front end in this embodiment refers to the end of the automatic injector that is used to inject towards the human body, i.e. the end of the automatic injector that extends out of the needle 91, and when the automatic injector does not contain the needle cylinder 9 and the needle 91, the front end refers to the end of the needle protecting cover 2 that extends out of the housing 1; the rear end in this version is opposite the front end, i.e. the other end of the auto-injector opposite the front end.

The push rod 3 is a main component for directly pushing the piston 93 to realize automatic injection, the push rod 3 is arranged inside the shell 1 in a sliding manner along the axial direction, the front end of the push rod 3 is used for pushing the piston 93 in the needle cylinder 9, the driving elastic part acts on the push rod 3 and drives the push rod 3 to slide towards the front end of the needle cylinder 9, so that the push rod 3 can automatically complete injection action under the elastic action of the driving elastic part, the driving elastic part and the push rod 3 can be kept in an initial assembly state under the limiting action of other components to prevent liquid medicine in the needle cylinder 9 from being pushed out by the push rod 3, the periphery of the push rod 3 is provided with a push rod limiting structure, and the push rod limiting structure is used for interacting with other components to keep the push rod 3 in the initial assembly.

The sound tube 4 is a main action component which sends out a prompt signal after the push rod 3 finishes injection, the sound tube 4 is sleeved on the periphery of the push rod 3 in a sliding mode along the axial direction, the driving elastic piece acts on the sound tube 4 and drives the sound tube 4 to slide towards the rear end of the shell 1, so that the sound tube 4 can achieve a signal prompt function under the elastic action of the driving elastic piece, and the driving elastic piece and the sound tube 4 can be kept in an initial assembly state under the limiting action of other components to avoid the sound tube 4 from sliding towards the rear end of the shell 1; the sound tube 4 is provided with a push rod limiting and matching structure; a sound tube limiting structure is arranged between the sound tube 4 and the inner tube 5 and used for keeping the relative position between the sound tube 4 and the inner tube 5 fixed in an initial assembly state.

It should be noted that the push rod 3 of the present invention can be designed as a solid or hollow rod-like structure, or a tubular structure, etc.; the drive elastic component can adopt spiral spring, stretch cord, metal shrapnel etc. preferably, push rod 3 in this scheme is hollow shaft-like structure, and the drive elastic component is for setting up in the inside push rod spring 7 of push rod 3, and push rod spring 7 compression arranges between the front end of push rod 3 and the rear end of a sound section of thick bamboo 4. Because the push rod spring 7 is in a compressed state, pressure towards the front end direction of the shell 1 can be applied to the push rod 3, pressure towards the rear end direction of the shell 1 can be applied to the sound tube 4, once the push rod 3 is separated from the axial limit of the inner tube 5, the push rod 3 can move towards the front end direction of the shell 1 under the elastic force action of the push rod spring 7, and meanwhile, the piston 93 is pushed to perform injection; once the sound tube 4 is separated from the axial limit of the inner tube 5, the sound tube 4 moves towards the rear end of the shell 1 under the action of the elastic force of the push rod 7 and sends out a prompt signal.

Preferably, the spring guide rod 71 is slidably disposed inside the push rod 3, the push rod spring 7 is sleeved on the outer periphery of the spring guide rod 71, the rear end of the push rod spring 7 abuts against the guide rod end 711 at the rear end of the spring guide rod 71, the front end of the push rod spring 7 abuts against the front end of the push rod 3, and the spring guide rod 71 serves as a guide member of the push rod spring 7, so that the push rod spring 7 can perform telescopic motion along the spring guide rod 71 in the processes of compression, reset and release, thereby reducing the twisting amount of the push rod spring 7 and ensuring smooth extension and retraction of the push rod spring 7.

The inner tube 5 is a tubular element fixed in position with respect to the casing 1 and able to provide a guide for the axial movement of the sound tube 4. The inner tube 5 can act together with the release ring 6 in an initial assembly state to fix the push rod 3 and the banger 4, and can release the push rod 3 after the release ring 6 moves to the rear end, thereby implementing an automatic injection function of the push rod 3. The inner tube 5 is fixed in the casing 1 inside and the periphery of a sound section of thick bamboo 4 is located to the cover, and the periphery of inner tube 5 is located to release ring 6 slip cover, and the inner tube 5 is equipped with can be along the first clamping 55 of radial elastic movement, and first clamping 55 is along radial outside skew under self elasticity effect to make first clamping 55 can in time relieve the axial fixity to push rod 3 after losing the limiting displacement of release ring 6, and then realize automatic injection.

When the automatic injector is in an initial assembly state, namely a state before injection, the release ring 6 is positioned to radially press the first clamp 55 towards the sound tube 4 and the push rod 3, namely, the first clamp 55 can radially and inwardly deviate under the limiting action of the inner wall of the release ring 6 and is mutually clamped and limited with the push rod limiting structure through the push rod limiting matching structure, so that the axial position of the push rod 3 is fixed by the first clamp 55, and the push rod 3 is prevented from axially moving before injection. Wherein, the push rod limiting structure can be designed into a pit structure, a groove structure or a sawtooth structure capable of axially limiting with the first clamp 55, and the like, and preferably, the push rod limiting structure in the present scheme is designed into a push rod ring groove 31 arranged around the periphery of the push rod 3, as shown in fig. 12 to 14. The push rod limiting and matching structure is used for providing an avoiding space for the clamping and matching of the first clamping device 55 and the push rod limiting structure, or is used for transmitting the clamping force of the first clamping device 55 to the push rod limiting structure. Preferably, the push rod limit fitting structure is an acoustic tube avoiding notch 42 opened in the side wall of the acoustic tube 4, and the acoustic tube avoiding notch 42 is arranged along the axial extension of the acoustic tube 4, as shown in fig. 15 and 17.

In addition, sound a section of thick bamboo limit structure can be restricted under the supporting role of the outer wall of push rod 3 and be sounded the relative slip of a section of thick bamboo 4 and inner tube 5, push rod 3 can break away from the support to a section of thick bamboo limit structure of sounding after sliding to the front end and predetermineeing the distance to make push rod 3 can relieve the axial fixity to a section of thick bamboo 4 of sounding after injecting predetermined volume liquid medicine or injecting and finishing, and then make the drive elastic component can push a section of thick bamboo 4 to 1 rear end of casing, send cue signal simultaneously. The sound tube limiting structure in the present scheme may be designed into a pin, a protrusion, a sawtooth, and the like, and preferably, the sound tube limiting structure in the present scheme includes a sound tube protrusion 41 disposed on an outer wall of the sound tube 4 and an inner tube locking hole 53 disposed on the inner tube 5 and used for limiting and locking with the sound tube protrusion 41, as shown in fig. 15 to 19.

It should be noted that, after the push rod 3 finishes injecting, the sound tube 4 can move towards the rear end of the housing 1 under the driving of the driving elastic element by removing the support of the sound tube limiting structure, and different types of prompt signals can be sent out in various ways in the moving process of the sound tube 4 or when the sound tube 4 moves to a specified position, so as to remind a user of finishing injecting. For example, the sound tube 4 and a structure at the rear end of the shell 1 can collide with each other and send out a sound prompt signal; or the sound prompt signal is sent out through the mutual friction between the sound tube 4 and the inner wall of the inner tube 5 in the backward moving process; or the rear end of the shell 1 is provided with a through hole and the sound tube 4 can slide out of the through hole, so that the hand of a user can be impacted and a tactile reminding signal can be generated; or a buzzer or a prompting lamp is triggered by the sound tube 4 when the sound tube slides to a certain position, so that sound or light prompting is realized, and the like. Preferably, this scheme adopts the mode of sound suggestion to remind the user that the injection finishes, and the rear end of casing 1 is equipped with and is used for hitting spacing signal structure with a sound section of thick bamboo 4. Specifically, the signal structure may be an end plate structure at the rear end of the housing 1, or a pressing sound-producing structure disposed at the rear end of the housing 1, or a metal sheet, etc. Preferably, the signal structure in this embodiment is an end plate 120 fixed to the rear end of the housing 1, as shown in fig. 29 and 30, when the push rod 3 finishes injecting, the sound tube 4 impacts the end plate 120 backwards, and simultaneously emits an impact sound, thereby alerting the user. In order to increase the impact sound and facilitate the auditory recognition of the user, in the present embodiment, the end plate 120 is designed to have a structure with a relatively high rigidity, such as a glass plate, a resin plate, a metal plate, or the like, or a metal sheet or a glass sheet with a relatively high rigidity is designed on the side where the end plate 120 and the sound tube 4 face each other, so that a crisp and easily recognizable prompt sound signal can be emitted when the two impact each other.

It should be noted that, in the automatic injector of the present embodiment that includes the pre-filled and sealed syringe 9 in the initial assembly state, in order to protect the needle 91 from being contaminated by the outside, the needle sheath 92 provided by the syringe 9 may be used to protect the needle 91, and other protection structures may be designed at the front end of the automatic injector to protect the needle sheath 92 and the needle 91 for the second time. Preferably, as shown in fig. 4, the present solution provides an autoinjector further comprising a needle cap 14, the needle cap 14 being detachably connected to the front end of the needle shield 2. Before an injection is required, the user can manually remove the needle cap 14, so that the needle shield 2 can be moved in the direction of the rear end of the housing 1 and expose the needle 91 or the needle sheath 92 under the pressing action.

Preferably, the rear end of the needle cap 14 is provided with a hook 143 for engaging with the rear end of the needle sheath 92, and the hook 143 can apply a pulling force to the needle sheath 92 in a front direction. As shown in fig. 4 and 5, the needle cap 14 is a tubular structure as a whole, a needle cap inner cylinder 145 penetrates through the inside of the needle cap 14, a needle sheath mounting hole 141 for accommodating the needle sheath 92 is formed in the inner ring of the needle cap inner cylinder 145, the front end of the needle cap inner cylinder 145 is fixedly connected with the front end of the needle cap outer cylinder or is designed to be an integral structure, one or more pairs of hooks 143 are arranged at the rear end of the needle cap inner cylinder 145, the hooks 143 are elastic hook-shaped structures extending from the side wall of the needle cap inner cylinder 143 to the inside of the needle sheath mounting hole 141, and in order to facilitate the hooks 143 to be clamped into the rear end of the needle sheath 92 during assembly, the rear end face of the hooks 143 is designed to be a guide inclined plane gradually approaching the center of the needle cap inner cylinder 145 from back to front as shown in fig. 4 and 5. When the automatic injector is assembled, the hook 143 can be engaged with the rear end face of the sheath 92 from the front end to the rear end, and when the automatic injector is used, the hook 143 can be used to apply a pulling force to the sheath 92 when the needle cap 14 is removed, so that the sheath 92 is separated from the needle 91. The hook 143 extends inward and toward the front end of the needle cap 14, so as to hook the needle sheath 92 more firmly, thereby ensuring effective removal of the needle sheath 92. In addition, a space for inserting the front end of the needle shield 2 is reserved between the outer cylinder of the needle cap 14 and the needle cap inner cylinder 145.

Preferably, an anti-disengagement concave-convex matching structure is arranged between the inner ring of the needle cap 14 and the circumferential direction of the needle shield 2, and before the injector is used, the anti-disengagement concave-convex matching structure can prevent the needle cap 14 from being accidentally separated from the shell 1 or the needle shield 2. Specifically, as shown in fig. 4, in the present embodiment, an anti-disengaging concave-convex matching structure is provided between the inner wall of the outer cylinder of the needle cap 14 and the outer wall of the needle shield 2, the anti-disengaging concave-convex matching structure specifically includes a needle cap anti-disengaging limiting part 142 and a needle shield anti-disengaging limiting part 21, the needle cap anti-disengaging limiting part 142 shown in fig. 4 is a convex structure, and the needle shield anti-disengaging limiting part 21 is a concave structure matched with the needle cap anti-disengaging limiting part, which may be interchanged, that is, the needle cap anti-disengaging limiting part 142 is a concave structure, and the needle shield anti-disengaging limiting part 21 is a convex structure, which may also play the role of. Of course, the utility model discloses can also set up anticreep unsmooth cooperation structure between needle cap inner tube 145 and needle shield 2, this text is no longer repeated.

Preferably, a needle cap limiting structure 144 for limiting the movement of the needle cap 14 relative to the housing 1 in the rear end direction is arranged between the housing 1 and the needle cap 14. As shown in fig. 5 and 6, the needle cap limiting structure 144 is specifically designed as a convex structure fixed at the rear end of the outer cylinder of the needle cap 14, the front end of the housing 1 is designed with a groove structure matched with the convex structure, when the needle cap 14 is installed at the front end of the housing 1, the needle cap limiting structure 144 is matched with the groove structure, which can not only limit the needle cap 14 from moving towards the rear end relative to the housing 1, but also limit the needle cap 14 from rotating along the circumferential direction relative to the housing 1.

As shown in fig. 9, preferably, the syringe fixing structure is a syringe fixing cylinder 110 fixed inside the housing 1, a syringe clamping jaw 112 for being in limit fit with a front end shoulder of the syringe 9 is arranged at the front end of the syringe fixing cylinder 110, a main body of the syringe 9 is accommodated inside the syringe fixing cylinder 110, the front end shoulder of the syringe 9 abuts against the syringe clamping jaw 112, and during injection, the syringe 9 can be stably fixed in the syringe fixing cylinder 110 without shaking, and the rear end flange 94 of the syringe 9 is prevented from being broken to press the syringe 9 out of the housing 1. Of course, the syringe fixing structure in the present invention can also be designed to be fixed on the syringe fixing ring or the syringe fixing step and other structures inside the casing 1, and will not be described herein.

As shown in fig. 10 and 11, preferably, the rear end of the syringe fixing barrel 110 is provided with a support 114 for engaging with the rear end flange 94 of the syringe 9 in a limited manner, and an elastic cushion 113 is provided between the support 114 and the front end surface of the rear end flange 94 of the syringe 9. The main function is to provide an elastic support for the needle cylinder 9 during the injection process, so as to avoid the breakage of the glass needle cylinder 9 caused by the overlarge thrust released instantly.

Preferably, the front end of the inner tube 5 abuts against the rear end surface of the rear end flange 94 of the cylinder 9, and the rear end of the inner tube 5 abuts against the rear end of the housing 1. So set up, the inner tube 5 is fixed in the casing 1 through the butt effect at both ends inside to for syringe 9 provides stable support. Further preferably, as shown in fig. 18 and 21, the front end 52 of the inner tube 5 abuts against the rear flange 94 of the needle cylinder 9, the front end 52 of the inner tube may be designed as a resilient support leg structure, and the front end 52 of the inner tube will continuously press against the rear flange 94 to provide a stable pressure, so that the rear flange 94 of the needle cylinder 9 can always press against the resilient pad 113, and the rear flange 94 is prevented from being damaged.

Preferably, the rear end of the housing 1 is provided with an annular protrusion 121 coaxially matched with the rear end of the inner tube 5, and a rotation limiting structure for preventing the inner tube 5 from rotating is arranged between the side wall of the housing 1 and the inner tube 5. Specifically, annular protrusion 121 is used for guaranteeing that inner tube 5 does not rock in casing 1 to for release ring 6 and sound parts such as a section of thick bamboo 4 provide firm sliding support, can also be used for guaranteeing the axiality of inner tube 5 and casing 1, at this moment, when playing a section of thick bamboo 4 and moving to the rear end of casing 1, sound the rear end of a section of thick bamboo 4 and can strike annular protrusion 121's preceding terminal surface, thereby send the striking sound signal in order to realize the suggestion. The rotation limiting structure ensures that the inner tube 5 cannot rotate relative to the housing 1. The rotation limiting structure may be designed in various structural forms, for example, a limiting block structure is arranged between the side wall of the housing 1 and the inner tube 5, or a limiting groove structure is arranged, or the outer profile of the end section of the inner tube 5 is designed in a non-circular structure such as a square, an ellipse, etc., and the rotation of the inner tube 5 is limited by the profile fitting, etc. Preferably, in the present embodiment, the inner wall of the housing 1 is designed with an inner tube anti-rotation limiting groove 122, which may be designed as a T-shaped notch groove, and the front end of the inner tube 5 is designed with an inner tube anti-rotation protrusion 51 correspondingly matched with the inner tube anti-rotation limiting groove, as shown in fig. 29 and 30.

It should be noted that the housing 1 of the automatic injector provided by the present invention may be designed as an integral structure, or may be designed as a split structure, for example, it is divided into two or more sections of tubular structures, preferably, as shown in fig. 1, the housing 1 includes a front housing 11 and a rear housing 12, and the front housing 11 is connected to the front end of the rear housing 12. The front housing 11 mainly provides mounting support for the pre-filled syringe 9 and ensures that the shield 2 maintains a stable axial movement, and the rear housing 12 mainly provides mounting space for the inner tube 5 and other components such as the return spring. Specifically, the front housing 11 and the rear housing 12 can be fixed by a plurality of means, such as screw connection, snap connection, etc., and preferably, the present solution is designed with a rear housing mounting ring groove 123 at the front end of the rear housing 12 for connecting and fixing the front housing 11, as shown in fig. 29. Further preferably, the autoinjector that this scheme provided is when leaving the factory as semi-manufactured goods, casing 1 is the components of a whole that can function independently design, syringe assembly manufacturer assembles the cylinder 9 of embedment in advance in casing 1 again, then connect front casing 11 and back casing 12 fixed, in order to avoid user's reuse syringe, this scheme still has the structure of preventing tearing open in front casing 11 and back casing 12 junction design, for example adopt sticky fixed mode, or adopt interference fit mode, or design both junctions for the disposable connection structure of easy rupture, can't be in the same place again after tearing open, etc..

Preferably, in order to facilitate the user to observe the pushing situation of the push rod 3, the housing 1 and the needle shield 2 are both provided with an observation window 13 extending along the axial direction, i.e. hollow openings opened on the side walls of the housing 1 and the needle shield 2. Of course, the utility model discloses in can also design observation window 13 for transparent lid structure, perhaps design the spare part and the cylinder 9 itself that lie in the cylinder 9 periphery such as casing 1, protecting needle shield 2 for transparent structure, also can the person of facilitating the use observe the injection condition.

The release ring 6 is a sliding part with a cylindrical structure, and the main function of the release ring is to limit the first clamp 55 of the inner tube 5 to bounce outwards in an initial assembly state, so as to ensure that the push rod 3 is fixed before injection, and when the release ring 6 moves towards the rear end direction of the shell 1 and the release ring 6 releases the radial limitation on the first clamp 55, the first clamp 55 can release the axial limitation on the push rod 3, so that the push rod 3 can realize automatic injection under the action of the push rod spring 7. Another function of the release ring 6 is to interact with the bang barrel 4 after the injection has been completed and returned to the initial axial position, thereby ensuring that the syringe is not reused.

When injection is needed, the needle shield 2 drives the release ring 6 to overcome the elastic force of the reset elastic element together, so that the release ring 6 slides towards the rear end direction of the shell 1, in order to facilitate the release ring 6 to slide relative to the inner tube 5, preferably, the inner tube 5 is provided with an inner tube avoiding groove hole 54 extending along the axial direction, the release ring 6 is provided with a second clamp 62 in sliding fit with the inner tube avoiding groove hole 54, the second clamp 62 can interact with the sound tube 4, and the outer side of the sound tube 4 is provided with a clamp limiting structure for limiting the second clamp 62 to move towards the rear end direction of the shell 1. Here, the second clip 62 may be designed as an elastic clip structure that can be elastically deformed in the radial direction, and the second clip 62 may interact with the sound tube 4 so as to abut against or rub against each other in the axial direction. After injection is finished, the sounding cylinder 4 moves to the rear end of the shell 1, the front end of the needle protecting cover 2 moves away from an injection part, at the moment, the release ring 6 moves towards the front end under the action of the reset elastic piece, and when the second clamp 62 of the release ring 6 moves to interact with the clamp limiting structure of the sounding cylinder 4, the release ring 6 cannot move towards the rear end of the shell 1 again due to the axial limiting function of the clamp limiting structure and the second clamp 62, so that secondary injection cannot be performed on the automatic injector, and the use safety is guaranteed. Wherein, the clip spacing structure can be designed into a plurality of structural forms, such as spacing hole structure, spacing saw tooth structure, spacing friction surface structure, etc., preferably, the present solution is designed with a clip spacing opening 43 on the side wall of the rattle barrel 4, as shown in fig. 15 to 17 and 26, as can be seen from the figure, in the initial assembly state, the clip spacing opening 43 is located at the front end of the second clip 62, therefore, the clip spacing opening 43 can not axially limit the second clip 62, after the injection is finished (shown in fig. 26), the second clip 62 moves towards the front end direction and is clipped in the clip spacing opening 43, at this moment, the inner edge of the rear end of the clip spacing opening 43 and the end face of the rear end of the second clip 62 abut against each other, thereby limiting the second clip 62 from moving towards the rear end of the housing 1 again. In addition, in order to facilitate the relative movement between the second clip 62 and the rattle cylinder 4, the present embodiment further includes a clip escape opening 44 formed in the side wall of the rattle cylinder 4, and as shown in fig. 15 to 17 and 26, the clip escape opening 44 is located in the rear end direction of the clip stopper opening 43.

It should be noted that the elastic resetting element is used as a retaining element for retaining the release ring 6 and the needle shield 2 in the initial axial position and a restoring element for restoring the release ring 6 and the needle shield 2 to the initial axial position after the injection is completed, the elastic resetting element can provide a continuous elastic action applied in the front end direction for the release ring 6, and specifically can adopt an elastic element such as a helical spring, an elastic rope or a metal elastic sheet, and preferably, the elastic resetting element is an elastic resetting spring 8, as shown in fig. 31, the elastic resetting spring 8 is arranged between the release ring 6 and the housing 1 in a compression manner. As shown in fig. 34, in this embodiment, a release ring rear end flange 61 for abutting against the return spring 8 is further provided at the rear end of the release ring 6, the front end of the return spring 8 abuts against the release ring rear end flange 61, the rear end of the return spring 8 abuts against the rear end inner wall of the rear housing 12, and the return spring 8 can be in a compressed state even in the initial assembly state.

The four parts of the needle cap 14, the needle shield 2, the front housing 11 and the elastic cushion block 113 described above form a retaining assembly of the front housing, and are mainly used for keeping the position of the fixed needle cylinder 9; the push rod 3, the bang tube 4, the inner tube 5, the release ring 6, the push rod spring 7, the spring guide rod 71, the return spring 8 and the rear shell 12 form a driving assembly of the rear shell, and are mainly used for realizing the function of driving injection.

It should be noted that each component of the automatic injector of the present invention can be made of various materials (for example, resin, metal, etc. commonly used in medical devices), and can also have different specifications and structures.

Referring to fig. 1 to 3 and 32 to 41, the whole using process of the automatic injector according to the present invention will be described.

Fig. 1 to 3 are a schematic view of the overall external structure of the auto-injector before use and two schematic longitudinal cross-sections, respectively, when the needle cap 14 of the auto-injector is also mounted at the front end of the housing 1. The front housing 11 is adapted to hold a syringe 9 containing a medicament, the syringe 9 may be a pre-filled syringe and have a needle 91 arranged at a front end of the syringe 9, in other embodiments the syringe 9 may be a medicament cartridge adapted to removably connect with the needle 91. The needle 91 is arranged open towards the front end of the front housing 11, the needle 91 being protected by a needle sheath 92, and the needle shield 2 projects out of the front end of the housing 1 and is able to protect the needle 91 and the needle sheath 92 in the initial assembled state prior to injection.

As shown in fig. 32, when preparing for injection, the needle cap 14 is removed to the front end, the front end of the needle shield 2 is exposed out of the housing 11, and the needle 91 is still shielded by the needle shield 2. Then, the housing 1 is held by hand, the front end of the housing 1 is aligned with the part of the body to be injected, the needle shield 2 is aligned with the part to be injected and pressed by force, at this time, the needle shield 2 is retracted towards the inside of the housing 1, and the needle 91 is exposed, so that the needle 91 can penetrate into the part to be injected. When the needle shield 2 is pushed backwards, the rear end surface of the needle shield 2 abuts against the front end of the release ring 6, the needle shield 2 overcomes the elastic force of the return spring 8 and drives the release ring 6 to move backwards relative to the housing 1 together and compress the return spring 8 until the second clips 62 of the release ring 6 abut against the inner tube escape slot 54 of the inner tube 5, as shown in fig. 33 to 35. Meanwhile, the inner ring protrusion 23 of the needle shield 2 abuts against the needle grip 112 inside the front case 11 to provide an auxiliary support for the shoulder at the front end of the needle cartridge 9.

In the process that the release ring 6 moves towards the rear end of the housing 1, the first clip 55 of the inner tube 5 is separated from the limit of the inner wall of the release ring 6, so as to release the clipping limit of the push rod 3, as shown in fig. 36 to 37, the push rod 3 slides towards the front end of the syringe 9 under the action of the push rod spring 7, and the liquid in the syringe 9 is injected into the body through the needle 91 through the piston 93, so that automatic injection is realized.

In the injection process of the push rod 3, the outer wall of the push rod 3 can provide a continuous supporting effect on the sound tube convex block 41, so that the relative fixation of the sound tube 4 and the inner tube 5 is ensured; when the push rod 3 slides for a predetermined distance, that is, after the push rod 3 has injected a predetermined amount of liquid into the syringe 9, the bang barrel protrusion 41 is separated from the support of the outer wall of the push rod 3, so that the bang barrel 4 can slide toward the rear end of the housing 1 under the action of the push rod spring 7. The sound tube 4 can prompt the user that the injection is finished through various modes such as sound production, light emission, friction, impact vibration and the like in the sliding process or after sliding for a certain distance, and the sound tube 4 and the annular protrusion 121 on the inner side of the end plate 120 of the rear shell 12 are mutually impacted to give a sound to prompt the completion of the injection in the scheme, as shown in fig. 38 and 39. The user need only pull the needle 91 out of the body to complete the injection procedure.

In addition, since the release ring 6 compresses the return spring 8 when pushed rearward, once the forward end of the shield 2 has been removed from the injection site, the release ring 6 loses its pushing force in the rearward direction and the release ring 6 is pushed by the return spring 8 in the forward direction, forcing the shield 2 back to the first stop step 111 of the forward housing 11, as shown in fig. 40. After the needle shield 2 returns to the initial axial position, the axial position of the rattle cylinder 4 moves a distance towards the rear end of the housing 1, so that the second clips 62 of the release ring 6 are clipped into the clip limiting openings 43 of the rattle cylinder 4, and the rattle cylinder 4 is axially limited by the clip limiting openings 43 and cannot move backwards again, as shown in fig. 40 and 41, so that the axial position of the needle shield 2 can be locked and the exposure of the needle 91 is avoided, that is, the automatic injector is prevented from being reused, and high use safety is ensured.

The utility model discloses the scheme has following beneficial effect:

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An autoinjector, comprising: the device comprises a shell (1), a needle protecting cover (2), a push rod (3), a sound tube (4), an inner tube (5), a release ring (6), a driving elastic element and a resetting elastic element;

a needle cylinder fixing structure for fixing the needle cylinder (9) is arranged in the shell (1), and an opening for the needle head (91) to extend out is formed in the front end of the shell (1);

the release ring (6) and the needle shield (2) are sequentially arranged on the inner side of the shell (1) in a sliding manner from the rear end to the front end, the needle shield (2) can extend out of the front end of the shell (1) and can slide towards the rear end relative to the shell (1) and push the release ring (6), and the reset elastic piece acts on the release ring (6) and drives the release ring (6) to push the needle shield (2) to slide towards the front end of the shell (1); the shell (1) is provided with a needle shield limiting structure for limiting the forward sliding distance of the needle shield (2) relative to the shell (1);

the push rod (3) is arranged in the shell (1) in an axially sliding mode, the front end of the push rod (3) is used for pushing a piston (93) in the needle cylinder (9), the driving elastic piece acts on the push rod (3) and drives the push rod (3) to slide towards the front end of the needle cylinder (9), and a push rod limiting structure is arranged on the periphery of the push rod (3);

the sounding cylinder (4) is sleeved on the periphery of the push rod (3) in an axially sliding manner, the driving elastic piece acts on the sounding cylinder (4) and drives the sounding cylinder (4) to slide towards the rear end of the shell (1), the sounding cylinder (4) is provided with a push rod limiting and matching structure, and a sounding cylinder limiting structure is arranged between the sounding cylinder (4) and the inner tube (5);

the inner pipe (5) is fixed in the shell (1) and sleeved on the periphery of the sound tube (4), the release ring (6) is sleeved on the periphery of the inner pipe (5) in a sliding mode, the inner pipe (5) is provided with a first clamping clip (55) capable of elastically moving along the radial direction, and the first clamping clip (55) is deflected outwards along the radial direction under the action of the elasticity of the first clamping clip;

first clamping (55) can be in along radial inside skew and pass through under the limiting displacement of the inner wall of release ring (6) the spacing cooperation structure of push rod with the mutual joint of push rod limiting structure is spacing, it can restrict under the supporting action of the outer wall of push rod (3) to sound a section of thick bamboo (4) with the relative slip of inner tube (5), push rod (3) can break away from behind the preset distance to the front end slip and to sound a section of thick bamboo limiting structure's support.

2. Auto-injector according to claim 1, characterized in that the rear end of the housing (1) is provided with a signal structure for limiting the impact with the sound tube (4).

3. An autoinjector according to claim 2, wherein said signal structure is an end plate (120) fixed to the rear end of the case (1).

4. An autoinjector according to claim 1, further comprising a needle cap (14), said needle cap (14) being removably connected to the forward end of said needle shroud (2).

5. An autoinjector according to claim 4, characterised in that the rear end of the cap (14) is provided with a catch (143) for interengaging with the rear end of the sheath (92), the catch (143) being capable of exerting a pulling force on the sheath (92) in a direction towards the front end.

6. An autoinjector according to claim 4, characterised in that an anti-slip male-female engagement formation is provided between the inner collar of the needle cap (14) and the periphery of the needle shroud (2).

7. An auto-injector according to claim 4, characterised in that a needle cap limiting structure (144) is provided between the housing (1) and the needle cap (14) for limiting the movement of the needle cap (14) in the direction of the rear end relative to the housing (1).

8. The automatic injector according to claim 1, characterized in that the syringe fixing structure is a syringe fixing barrel (110) fixed inside the housing (1), and the front end of the syringe fixing barrel (110) is provided with a syringe clamping jaw (112) for limiting and matching with the front end shoulder of the syringe (9).

9. The autoinjector of claim 8, wherein a support (114) for limit fitting with a rear flange (94) of the syringe (9) is provided at a rear end of the syringe fixing barrel (110), and an elastic cushion block (113) is provided between the support (114) and a front end face of the rear flange (94) of the syringe (9).

10. An autoinjector according to claim 1, wherein a forward end of the inner tube (5) abuts a rear end face of a rear end flange (94) of the barrel (9), and a rear end of the inner tube (5) abuts a rear end of the case (1).

11. An auto-injector according to claim 10, characterized in that the rear end of the housing (1) is provided with an annular protrusion (121) co-axially cooperating with the rear end of the inner tube (5), and a rotation-limiting structure for preventing the inner tube (5) from rotating is provided between the side wall of the housing (1) and the inner tube (5).

12. The automatic injector according to claim 1, characterized in that the push rod limit fitting structure is an rattle barrel avoiding notch (42) opened on the side wall of the rattle barrel (4), and the rattle barrel avoiding notch (42) is arranged along the axial extension of the rattle barrel (4).

13. The automatic injector according to claim 1, wherein the sound barrel limiting structure comprises a sound barrel convex block (41) arranged on the outer wall of the sound barrel (4) and an inner barrel clamping hole (53) arranged on the inner barrel (5) and used for limiting and clamping with the sound barrel convex block (41).

14. The autoinjector of claim 1, wherein the inner tube (5) is provided with an inner tube escape slot (54) extending in an axial direction, the release ring (6) is provided with a second clip (62) slidably fitted with the inner tube escape slot (54), the second clip (62) is capable of interacting with the rattle barrel (4), and a clip limiting structure for limiting the second clip (62) to move towards a rear end of the case (1) is provided on an outer side of the rattle barrel (4).

15. The autoinjector of claim 1, wherein the plunger (3) is a hollow rod-like structure, the drive spring is a plunger spring (7) disposed inside the plunger (3), and the plunger spring (7) is disposed in compression between a front end of the plunger (3) and a rear end of the bang barrel (4).

16. The automatic injector according to claim 15, characterized in that a spring guide rod (71) is slidably arranged inside the push rod (3), and the push rod spring (7) is sleeved on the outer periphery of the spring guide rod (71).

17. Auto-injector according to claim 1, characterized in that the return spring is a return spring (8), the return spring (8) being arranged in compression between the release ring (6) and the housing (1).

18. An auto-injector according to claim 1, characterised in that the housing (1) comprises a front housing (11) and a rear housing (12), the front housing (11) being connected to a forward end of the rear housing (12).

19. An autoinjector according to claim 1, wherein the housing (1) and the needle shroud (2) are each provided with an axially extending viewing window (13).

20. An autoinjector according to claim 1, wherein said shield retention means comprises a first retention step (111) provided on an inner wall of said case (1) and a second retention step (22) provided on an outer wall of said shield (2).