Automatic injection device

Abstract

An automatic injection device is disclosed. The syringe includes a barrel for containing the fluid, a needle arranged at a proximal end of the barrel, and a movable plunger rod movable within the barrel. The automatic injection device includes a syringe retaining assembly for retaining the syringe; and a syringe driving assembly including a housing and a driving mechanism releasably arranged in the housing. The driving mechanism includes a movable body moveable after the driving mechanism is released, a first driving spring and a second driving spring, wherein the second driving spring is configured to drive the barrel of the syringe to move proximally to insert the needle of the syringe into an injection site of a target, and the first driving spring is configured to drive the movable plunger rod to move proximally to carry out injection; and the first and second driving springs have different spring stiffnesses.

Description

AUTOMATIC INJECTION DEVICECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to Chinese Patent Application No. 202410544116.5 filed April 30, 2024, the disclosure of which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTIONField of the Invention

[0002] The present disclosure generally relates to the technical field of medical instruments. In particular, the present disclosure relates to a reusable automatic injection device.Description of Related Art

[0003] Some illnesses necessitate regular injections of drugs or products, for instance on a daily basis. In order to simplify the treatment, there have been some automatic injection devices (also called "self-injectors") that can load and drive syringes, such as pre-filled syringes, to allow patients to inject by themselves.

[0004] Self-injection capacity has always been the crucial driving force for developing automatic injection devices. As patients typically have no special injection skills, these automatic injection devices must be simple and safe to use. For example, it is generally required that the automatic injection device shall ensure insertion of a needle into a correct depth and ensure injection of a correct dose of products (that is, complete injection is required), and that the needle shall not be exposed before and after use to prevent any accidental needle-stick injury, or the like.

[0005] The existing automatic injection devices have some defects. For example, some automatic injection devices are disposable automatic injection devices, which may lead to high use costs; some automatic injection devices only use a single spring to complete both procedures of needle insertion and injection, which is difficult to balance the needle insertion speed and the injection speed; some automatic injection devices do not have a function of dose adjustment, thus unable to meet the injection requirements of the patients well; some automatic injection devices cannot shield the needle of the syringe well before or after use, which tends to result in contamination of the injected medications or accidental needle-stick injury; and so on.

[0006] Therefore, there is a demand to modify the existing automatic injection devices.

[0007] It should be noted that the subject matter claimed in the present application is not limited to the fields as described above, to only solving any shortcomings as mentioned above, and to embodiments that are only used or operated in the above-mentioned environments. Rather, this background is provided only to illustrate an exemplary technical field in which some embodiments described in the present application may be implemented.SUMMARY OF THE INVENTION

[0008] An object of the present disclosure is to solve one or more of the problems existing in the automatic injection devices in the prior art and realize other additional advantages.

[0009] The present disclosure provides an automatic injection device for automatically injecting a fluid in a syringe into an injection site of a target. The syringe comprises a barrel for containing the fluid, a needle arranged at a proximal end of the barrel, and amovable plunger rod movable axially in the barrel, wherein the movable plunger rod is capable of being driven toward the proximal end of the barrel to inject the fluid in the barrel into the injection site of the target via the needle. The automatic injection device comprises: a syringe retaining assembly for accommodating and retaining the syringe; and a syringe driving assembly including a housing and a driving mechanism releasably arranged in the housing. The driving mechanism comprises a movable body which can move after the driving mechanism is released, a first driving spring and a second driving spring, wherein the second driving spring is configured to drive the barrel of the syringe to move proximally to insert the needle of the syringe into an injection site of a target, and the first driving spring is configured to drive the movable plunger rod of the syringe to move proximally to carry out injection; and wherein the first driving spring and the second driving spring have different spring stiffnesses.

[0010] Here, it is particularly important to note that the syringe is not a part of the automatic injection device according to the present disclosure.

[0011] In the automatic injection device according to the present disclosure, by providing a first driving spring and a second driving spring for the driving mechanism of the syringe driving assembly and by selecting different spring stiffnesses for the first driving spring and the second driving spring according to actual conditions, not only can the universality of the driving mechanism be improved, but also the needle insertion speed and the injection speed of the syringe can be well balanced.

[0012] According to an embodiment of the present disclosure, the first driving spring has a spring stiffness smaller than that of the second driving spring. This enables the needle of the syringe to be inserted into an injection site of a target at a high speed toalleviate the pain of the target, and enables the syringe to have a low injection speed to meet the injection requirements.

[0013] According to an embodiment of the present disclosure, the housing of the syringe driving assembly includes an outer housing and an inner housing fixedly positioned inside the outer housing, wherein a distal end of the inner housing is provided with a spring- loaded pivotable locking element configured to releasably lock the driving mechanism in the inner housing.

[0014] According to an embodiment of the present disclosure, the pivotable locking element comprises a locking body, a torsion spring for spring-loading the locking body, and a pivoting shaft for installation of the torsion spring and allowing the locking body to pivot about it, wherein the locking body comprises two legs positioned at an angle to each other, an end portion of a first leg of the two legs includes a first protrusion and a second protrusion extending towards both sides respectively along a direction substantially perpendicular to both of an extending direction of the first leg and an extending direction of the pivoting shaft, wherein a distal end of the movable body of the driving mechanism includes a hook portion, and wherein the first protrusion is formed as a locking portion capable of releasably hooking the hook portion, and the second protrusion is formed as an unlocking portion.

[0015] According to an embodiment of the present disclosure, the movable body of the driving mechanism comprises two energy storage rods spaced apart from each other and a connecting element for fixedly connecting the two energy storage rods, wherein the two energy storage rods are configured to enable the movable body to move distally to compress the first driving spring and the second driving spring to enable them to store elastic potential energy respectively.

[0016] According to an embodiment of the present disclosure, the connecting element is disposed near the distal ends of the two energy storage rods and comprises a bottom wall and a connecting plate extending distally from an outer periphery of the bottom wall, and wherein the movable body comprises a spring strut extending distally from a central position of the bottom wall of the connecting element, the first driving spring is fitted over the spring strut, and the hook portion of the movable body is disposed at a distal end of the spring strut.

[0017] According to an embodiment of the present disclosure, the movable body further comprises a first driving element extending proximally from the bottom wall of the connecting element, and the first driving element is configured to drive the movable plunger rod of the syringe proximally under the driving of the first driving spring.

[0018] According to an embodiment of the present disclosure, the driving mechanism further comprises a first retaining element and a second retaining element for retaining the second driving spring, wherein the first retaining element and the second retaining element retain the second driving spring near proximal ends of the two energy storage rods, and wherein the first retaining element is configured to drive the barrel of the syringe proximally under the driving of the second driving spring after the driving mechanism is released to insert the needle of the syringe into the injection site of the target, and the second retaining element is fixedly disposed in the inner housing.

[0019] According to an embodiment of the present disclosure, the automatic injection device comprises an unlocking lever configured to push the second protrusion of the locking body of the pivotable locking element distally, so that the locking body pivots about the pivoting shaft to disengage the first protrusion from the hook portion of the movable body of the driving mechanism.

[0020] According to an embodiment of the present disclosure, the syringe driving assembly further comprises a dose adjusting mechanism, wherein the dose adjusting mechanism comprises an adjusting gear, a driven gear assembly in meshed connection with the adjusting gear, a screw connected to the driven gear assembly and including a threaded section, and an adjusting nut fitted over the threaded section of the screw in an axially movable manner.

[0021] According to an embodiment of the present disclosure, the driven gear assembly comprises a driven gear, and an extension rod fixedly connected with the driven gear and including a cavity, wherein the screw further comprises a first section located at a distal side of the threaded section and a second section located at a proximal side of the threaded section, and wherein the first section of the screw is configured to be inserted into the cavity of the extension rod in such a way that it is capable of moving axially but unable to rotate relative to the extension rod, while a proximal end of the second section of the screw is configured to be always abutted against a selected component of the syringe retaining assembly. By such configuration, no matter whether the selected component moves or not during operation, the dose adjusting mechanism always takes the position where the selected component is located after the needle is inserted into the target as the reference point or the injection zero point, so that the to-be-injected dose having been adjusted is not affected by any change of the position of the selected component.

[0022] According to an embodiment of the present disclosure, an elastic pressing element is provided in the cavity of the driven gear assembly to enable the proximal end of the second section of the screw to be always abutted against the selected component.

[0023] According to an embodiment of the present disclosure, the adjusting gear is configured to be of a cylindrical shape and includes an outer peripheral surface and aninner peripheral surface, wherein the inner peripheral surface of the adjusting gear is provided with internal teeth, and the driven gear is provided with external teeth, and the internal teeth and the external teeth are in meshed connection.

[0024] According to an embodiment of the present disclosure, the movable body of the driving mechanism includes a dose control element, and the adjusting nut is positioned at a proximal side of the dose control element and includes a stopper for stopping the dose control element from moving proximally.

[0025] According to an embodiment of the present disclosure, the adjusting nut further comprises an adjusted-dose indicating element. This endows the automatic injection device according to the present disclosure with better visibility.

[0026] According to an embodiment of the present disclosure, the dose adjusting mechanism further comprises a dose display element including a rectangular body and an elongated opening provided in the rectangular body, wherein the rectangular body is provided with a plurality of dose display scales, and wherein the adjusted-dose indicating element is capable of being exposed from the elongated opening and is movable within the elongated opening. The adjusted-dose indicating element of the adjusting nut may be adjusted to align with one of the dose display scales to set the desired injection dose, which is helpful for convenient operation.

[0027] According to an embodiment of the present disclosure, the housing of the syringe driving assembly has a visual window, in which the dose display element is presented.

[0028] According to an embodiment of the present disclosure, the visual window has a length larger than that of the dose display element. This enables the dose display element to be always presented in the visual window regardless of whether it moves during dose adjustment.

[0029] According to an embodiment of the present disclosure, the dose control element comprises an injection indication mark for indicating whether injection has been completed.

[0030] According to an embodiment of the present disclosure, the syringe retaining assembly comprises a housing and a syringe retaining mechanism accommodated in the housing of the syringe retaining assembly, wherein the syringe retaining mechanism comprises a syringe retaining element for retaining the syringe, a needle shielding element for shielding the needle of the syringe, and a compressible coil spring disposed between the syringe retaining element and the needle shielding element, and wherein the coil spring has an initial state, in which the coil spring is in an extended state so that the needle shielding element is capable of shielding the needle of the syringe, and a compressed state, in which the coil spring is contracted to allow the needle of the syringe to extend out of the needle shielding element.

[0031] According to an embodiment of the present disclosure, the syringe retaining mechanism further comprises a depth adjusting mechanism for adjusting an insertion depth of the needle of the syringe in the target, the depth adjusting mechanism comprising a depth adjusting element and a depth limiting element, wherein the depth limiting element is configured as a stopper fixedly disposed on the syringe retaining element, and the depth adjusting element includes a plurality of steps with different heights and is mounted on the syringe retaining element at a proximal side of the depth limiting element in such a way that it is rotatable and does not limit axial movement of the syringe retaining element.

[0032] According to an embodiment of the present disclosure, the needle shielding element of the syringe retaining assembly comprises an elongated trigger element, whichis capable of releasing the driving mechanism of the syringe driving assembly after the elongated trigger element moves distally by a predetermined distance.

[0033] According to an embodiment of the present disclosure, the automatic injection device further comprises a needle cap removing assembly with a needle cap removing element, the needle cap removing element including a housing and a needle cap removing member disposed at a central position of the housing of the needle cap removing element, wherein the housing of the needle cap removing element is capable of being fitted over the syringe retaining assembly, and the needle cap removing member is capable of hooking an end surface of the needle cap of the syringe mounted inside the syringe retaining assembly.

[0034] According to an embodiment of the present disclosure, the needle cap removing member comprises a plurality of elastic fingers distributed along a circumference and a central cavity surrounded by the plurality of elastic fingers, wherein each elastic finger comprises a hook portion extending radially inward, and wherein the needle cap of the syringe is capable of extending into the central cavity of the needle cap removing member to allow the hook portion of each elastic finger of the needle cap removing member to hook the end surface of the needle cap.

[0035] According to an embodiment of the present disclosure, the needle cap removing assembly further comprises a snap assembly for releasably snapping the needle cap removing assembly onto the housing of the syringe retaining assembly, the snap assembly comprising a pair of spring-loaded snap elements, and wherein each snap element comprises a hook portion, and the housing of the syringe retaining assembly is provided with a protrusion mated with the hook portion of each snap element. The snap assemblycan prevent the needle cap removing assembly from being accidentally removed from the automatic injection device.

[0036] According to an embodiment of the present disclosure, each snap element includes an elongated body, the hook portion disposed at a first end of the elongated body, and a torsion spring disposed at a second end of the elongated body opposite to the first end, wherein the housing of the needle cap removing element includes a pair of openings, and the pair of snap elements are arranged in the pair of openings in a spring loaded manner respectively, with the hook portions facing inside of the housing of the needle cap removing element.

[0037] According to an embodiment of the present disclosure, the needle cap removing assembly further comprises a needle cap releasing assembly for releasing the needle cap accommodated in the central cavity of the needle cap removing member, the needle cap releasing assembly is configured to at least partially extend into the central cavity of the needle cap removing member, and the needle cap releasing assembly is configured to deflect each elastic finger of the needle cap removing member outward when it moves towards the inside of the needle cap removing element, thereby disengaging the hook portion of each elastic finger from the end surface of the needle cap.

[0038] According to an embodiment of the present disclosure, the needle cap releasing assembly comprises a needle cap releasing element and a retaining element for retaining the needle cap releasing element in the housing of the needle cap removing element in an axially movable manner, wherein the needle cap releasing element comprises a first section for releasing the needle cap, a second section sleeved with a compressible spring element, and a third section for retaining the spring element, the first section being configured to at least partially extend into the central cavity of the needle cap removingmember and deflect each elastic finger of the needle cap removing member outward when it moves toward the inside of the needle cap removing element, and wherein the retaining element is fitted over the second section of the needle cap releasing element. Such a configuration makes it possible to easily release the needle cap accommodated in the central cavity of the needle cap removing member by moving the needle cap releasing element towards the inside of the needle cap removing element, and the operation is very simple.

[0039] According to an embodiment of the present disclosure, the retaining element of the needle cap releasing assembly comprises a cylindrical body and a pair of elastic fingers disposed opposite to each other on the cylindrical body, and each elastic finger of the retaining element of the needle cap releasing assembly comprises a hook portion extending outward for retaining the retaining element of the needle cap releasing assembly together with the needle cap releasing element inside the housing of the needle cap removing element.

[0040] According to an embodiment of the present disclosure, the spring element is located within the retaining element of the needle cap releasing assembly and is supported between a bottom wall of the retaining element of the needle cap releasing assembly and an end surface of the third section of the needle cap releasing element.

[0041] It should be noted that aspects of the present disclosure described for one embodiment can be included in other different embodiments, although they are not specifically described for the other different embodiments. In other words, all embodiments and / or features of any embodiments can be combined in any way and / or combination as long as they are not contradictory with each other.BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to easily understand the above and other features and advantages of the present disclosure, the present disclosure will be described in more detail with reference to the specific embodiments shown in the attached drawings. These drawings depict only typical embodiments of the present disclosure and are therefore not to be considered as limiting the scope of the present disclosure, in which:

[0043] Figs, la and lb are perspective views of an automatic injection device as viewed from different perspectives according to an embodiment of the present disclosure;

[0044] Fig. 1c is an exploded view of the automatic injection device of Figs, la and lb;

[0045] Fig. Id is a sectional view of the automatic injection device of Figs, la and lb;

[0046] Figs. 2a and 2b are perspective views of the automatic injection device as viewed from different perspectives according to an embodiment of the present disclosure, in which a housing of the automatic injection device is removed to show its internal structure;

[0047] Fig. 3 is a schematic perspective view of a syringe used in cooperation with the automatic injection device according to an embodiment of the present disclosure;

[0048] Figs. 4a and 4b are perspective views of an outer housing of a syringe driving assembly as viewed from different perspectives according to an embodiment of the present disclosure;

[0049] Figs. 5a-5c are perspective views of an inner housing of the syringe driving assembly as viewed from different perspectives according to an embodiment of the present disclosure;

[0050] Figs. 6a and 6b are perspective views of a fastening element as viewed from different perspectives according to an embodiment of the present disclosure;

[0051] Fig. 7 is a perspective view of a driving mechanism of the syringe driving assembly according to an embodiment of the present disclosure;

[0052] Figs. 8a and 8b are perspective views of a movable body of the driving mechanism as viewed from different perspectives according to an embodiment of the present disclosure;

[0053] Fig. 8c is a perspective view of the movable body of Figs. 8a and 8b when loaded with a first driving spring;

[0054] Figs. 9a and 9b are perspective views of a first retaining element for a second driving spring of the driving mechanism, as viewed from different perspectives, according to an embodiment of the present disclosure;

[0055] Figs. 10a and 10b are perspective views of a second retaining element for the second driving spring of the driving mechanism, as viewed from different perspectives, according to an embodiment of the present disclosure;

[0056] Fig. 11 is a perspective view of the driving mechanism of Fig. 7 when locked by a spring-loaded pivotable locking element;

[0057] Figs. 12a and 12b are perspective views of the spring-loaded pivotable locking element according to an embodiment of the present disclosure;

[0058] Fig. 12c is a partial enlarged view showing that the spring-loaded pivotable locking element shown in Figs. 12a and 12b is mounted in the inner housing shown in Figs. 5a to 5c;

[0059] Fig. 12d is a perspective view showing that the driving mechanism is locked in the inner housing by the spring-loaded pivotable locking element;

[0060] Fig. 13a is a perspective view of an unlocking element for unlocking the spring- loaded pivotable locking element of Figs. 12a and 12b to release the driving mechanism according to an embodiment of the present disclosure;

[0061] Fig. 13b is a partial enlarged view of the unlocking element of Fig. 13a;

[0062] Fig. 13c is a perspective view showing that the unlocking element of Fig. 13a is unlocking the spring-loaded pivotable locking element of Figs. 12a and 12b;

[0063] Fig. 14 is a perspective view of a dose adjusting mechanism according to an embodiment of the present disclosure;

[0064] Figs. 15a and 15b are perspective views of an adjusting gear as viewed from different perspectives according to an embodiment of the present disclosure;

[0065] Fig. 16a is a perspective view of a driven gear shaft according to an embodiment of the present disclosure, in which a non-circular inner cavity of the driven gear shaft is shown;

[0066] Fig. 16b is a perspective view of an adjusting screw according to an embodiment of the present disclosure, in which a non-circular first rod portion located at an end of the adjusting screw is shown;

[0067] Fig. 16c is a sectional view showing that the non-circular first rod portion of the adjusting screw of Fig. 16b is axially movably inserted into the non-circular inner cavity of the driven gear shaft of Fig. 16a;

[0068] Fig. 17 is a perspective view of an adjusting nut according to an embodiment of the present disclosure;

[0069] Fig. 18 is a perspective view of a dose display element according to an embodiment of the present disclosure;

[0070] Fig. 19 is a perspective view showing that the dose display element of Fig. 18 is axially movably arranged in a window of the outer housing of Fig. 4b;

[0071] Figs. 20a and 20b are perspective views of a syringe retaining assembly as viewed from different perspectives according to an embodiment of the present disclosure;

[0072] Figs. 21a-21c are perspective views of a housing of the syringe retaining assembly as viewed from different perspectives according to an embodiment of the present disclosure;

[0073] Fig. 22 is a perspective view of a syringe retaining mechanism of the syringe retaining assembly according to an embodiment of the present disclosure;

[0074] Figs. 23a and 23b are perspective views of a syringe retaining element of the syringe retaining mechanism as viewed from different perspectives according to an embodiment of the present disclosure;

[0075] Fig. 24 is a perspective view of a needle shielding element for shielding a needle of the syringe according to an embodiment of the present disclosure;

[0076] Figs. 25a and 25b are perspective views of a depth adjusting element for adjusting the insertion depth of the needle of the syringe, as viewed from different perspectives, according to an embodiment of the present disclosure;

[0077] Fig. 26 is a perspective view of a mounting element for rotatably mounting the depth adjusting element on the syringe retaining element according to an embodiment of the present disclosure;

[0078] Fig. 27 is a perspective view of an operating element for rotating the depth adjusting element of Figs. 25a and 25b according to an embodiment of the present disclosure;

[0079] Fig. 28 is a perspective view of a limiting element for stopping the syringe retaining assembly within the housing of the syringe retaining assembly of Figs. 21a to 21c according to an embodiment of the present disclosure;

[0080] Figs. 29a and 29b are perspective views of the syringe retaining assembly having the limiting element, in which the housing of the syringe retaining assembly is removed;

[0081] Fig. 30 is a perspective view of a needle cap removing assembly for removing a needle cap of the syringe according to an embodiment of the present disclosure;

[0082] Fig. 31 is a perspective view showing that the needle cap removing assembly of Fig. 30 is mounted on the needle cap of the syringe, in which other components of the automatic injection device are removed;

[0083] Fig. 32 is a sectional view of the needle cap removing assembly of Fig. 30;

[0084] Figs. 33a and 33b are perspective views of a needle cap removing element of the needle cap removing assembly as viewed from different perspectives;

[0085] Fig. 34 is a perspective view showing a snap assembly for releasably snapping the needle cap removing assembly onto the housing of the syringe retaining assembly and a needle cap releasing assembly for releasing the needle cap according to an embodiment of the present disclosure;

[0086] Fig. 35 is a perspective view of an axially movable needle cap releasing element of the needle cap releasing assembly of Fig. 34;

[0087] Fig. 36 is a perspective view of a retaining element for retaining the movable needle cap releasing element of Fig. 35 on the needle cap removing element in an axially movable manner.

[0088] It is to be understood that like numeral references refer to like elements throughout. In the drawings, for the sake of clarity, the sizes of certain features may be modified and not drawn to scale.DETAILED EMBODIMENTS

[0089] The present disclosure will be described below with reference to the drawings, in which several embodiments of the present disclosure are shown. It should be understood, however, that the present disclosure may be implemented in many different ways, and is not limited to the example embodiments described below. In fact, the embodiments described hereinafter are intended to make a more complete disclosure of the present disclosure and to adequately explain the scope of the present disclosure to a person skilled in the art. It should also be understood that, the embodiments disclosed herein can be combined in various ways to provide many additional embodiments.

[0090] It should be understood that the wording in the specification is only used for describing particular embodiments and is not intended to define the present disclosure. All the terms used in the specification (including technical and scientific terms) have the meanings as normally understood by a person skilled in the art, unless otherwise defined. For the sake of conciseness and / or clarity, well-known functions or constructions may not be described in detail.

[0091] The singular forms “a / an” and “the” as used in the specification, unless clearly indicated, all contain the plural forms. The words “comprising”, “containing” and “including” used in the specification indicate the presence of the claimed features, but do not preclude the presence of one or more additional features. The wording “and / or” as used in the specification includes any and all combinations of one or more of the items listed.

[0092] In the specification, when an element is referred to as being “on”, “attached” to,“connected” to, “coupled” with, or “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present.

[0093] In the specification, the terms "first", "second" or "third" are used only for convenience of description and are not intended to be limiting. Any technical features represented by "first", "second" or "third" are interchangeable.

[0094] In the specification, words describing spatial relationships such as “up”, “down”, “forth”, “back”, “top”, “bottom” and the like may describe a relation of one feature to another feature in the drawings. It should be understood that these terms also encompass different orientations of the apparatus in use or operation, in addition to encompassing the orientations shown in the drawings. For example, when the apparatus shown in the drawings is turned over, the features previously described as being “below” other features may be described to be “above” other features at this time. The apparatus may also be otherwise oriented (rotated 90 degrees or at other orientations) and the relative spatial relationships will be correspondingly altered.

[0095] In the specification, the term "automatic" is used to indicate that at least some operations of a syringe (for example, insertion of a needle of the syringe into an injection site, injection of a fluid in the syringe into the injection site, or at least some of the similar operations) are carried out using a syringe driving assembly of an automatic injection device according to the present disclosure without being manually implemented by a user.

[0096] In the specification, the term "proximal" refers to the side facing or close to the injection site of a target when injection is performed using the automatic injection deviceaccording to the present disclosure, while "distal" refers to the side opposite to the"proximal" (i.e. , the side facing away or remote from the injection site of the target).

[0097] Referring to Figs, la to Id, an automatic injection device 10 according to an embodiment of the present disclosure is shown, which can be used to automatically inject a fluid (for example, a liquid medication or other fluids) in a syringe 20 into an injection site of a target (for example, living patients such as humans or animals, or other inanimate injected objects). The automatic injection device 10 is a reusable automatic injection device, and it only needs to place a new syringe 20 therein at each injection.

[0098] The syringe 20 may be a pre-filled syringe that has been filled with fluids, a pre- fillable syringe that can be filled with fluids before injection, or other suitable types of syringes. As shown in Fig. 3, the syringe 20 may include a barrel 21 for containing a fluid, a needle (not shown in Fig. 3) disposed at a proximal end of the barrel 21, and a movable plunger rod 22 that can be inserted into the barrel 21 from a distal end of the barrel 21 opposite to the proximal end and can move axially within the barrel 21. The distal end of the barrel 21 may include a flange 26 extending radially outward. The movable plunger rod 22 can be driven at least towards the proximal end of the barrel 21 so as to discharge the fluid in the barrel 21 and inject it into the injection site of the target via the needle. As for the pre-fillable syringe, the movable plunger rod 22 can also be pulled towards the distal end of the barrel 21 to suck fluids into the barrel 21 of the syringe. A distal end of the movable plunger rod 22 may be provided with a flange 23 extending radially outward from a body of the movable plunger rod. The movable plunger rod 22 can be pushed or pulled by means of the flange 23 to discharge the fluid in the barrel 21 or suck the fluid into the barrel 21. A proximal end of the movable plunger rod 22 opposite to the distal end may be provided with a plug (not shown in the figure). The syringe 20 may further include a needle cap 24 for shielding the needle of the syringe toavoid needle-stick injury to the user. The needle cap 24 has an end surface 25 facing the barrel 21 of the syringe.

[0099] Returning to Figs, la to Id, the automatic injection device 10 may at least include a syringe driving assembly 100 and a syringe retaining assembly 300. The syringe retaining assembly 300 may be configured to be loaded with and retain the syringe 20 therein. The syringe driving assembly 100 may be configured to drive the barrel 21 of the syringe 20 to insert the needle of the syringe 20 into an injection site of a target, and may be configured to drive the movable plunger rod 22 of the syringe 20 to inject the fluid in the syringe 20 into the injection site of the target. The syringe driving assembly 100 and the syringe retaining assembly 300 may be connected to each other (e.g., by snap connection, threaded connection, or in other suitable ways) to form the automatic injection device 10, for example, in a pen shape or other suitable shapes. In some embodiments according to the present disclosure, the automatic injection device 10 may further include a needle cap removing assembly 500. The needle cap removing assembly 500 may be configured to remove the needle cap 24 from the syringe 20 at least before injection. In some embodiments, the needle cap removing assembly 500 may also be configured to retain the removed needle cap 24 during injection, which can prevent the removed needle cap 24 from being accidentally discarded, rolling off the workbench, or contaminating other articles; and the needle cap removing assembly 500 may also be configured to mount the removed needle cap 24 onto the syringe 20 again after injection to shield the needle of the used syringe 20, which can avoid the accidental needle-stick injury that may be caused in the process of discarding the used syringe 20.

[0100] Referring to Figs. 4a to 19, the specific structure of the syringe driving assembly100 will first be described.

[0101] The syringe driving assembly 100 may include a housing and a driving mechanism 150 releasably disposed in the housing (as shown in Fig. 7). In order to facilitate assembly, in some embodiments according to the present disclosure, the housing of the syringe driving assembly 100 may include an outer housing 110 and an inner housing 130 fixedly positioned within the outer housing 110. In this embodiment, the driving mechanism 150 may be releasably disposed in the inner housing 130.

[0102] As shown in Figs. 4a and 4b, the outer housing 110 may have a generally cylindrical body 111. The body 111 may have a circular, elliptical, quadrilateral crosssection or a cross-section in other shapes. A proximal end (being the "lower end" in Figs. 4a and 4b) of the outer housing 110 may be provided with an opening 112. The inner housing 130 may extend from the opening 112 into the body 111. A distal end (being the "upper end" in Figs. 4a and 4b) of the outer housing 110 opposite to the proximal end may be provided with a limiting element 113 for limiting the inner housing 130. The limiting element 113 may extend radially inward from the body 111 to prevent the inner housing 130 from moving out of the distal end of the outer housing 110. The limiting element 113 may include an opening 114, which may allow at least a portion of the inner housing 130 (for example, a shaft portion 145 of the inner housing 130 shown in Figs. 5a and 5b) to protrude from the distal end of the outer housing 110 to cooperate with a fastening element (for example, a fastening element 30 shown in Figs. 6a and 6b) to thereby fix the outer housing 110 and the inner housing 130 together. An inner surface of the body 111 of the outer housing 110 may be provided with ribs 115 extending along the body 111. The ribs 115 may be cooperated with guide grooves 136 provided on the inner housing 130 so as to guide insertion of the inner housing 130 and prevent the inner housing 130 from rotating within the outer housing 110. In some embodiments according to the present disclosure, the body 111 of the outer housing 110 may further include avisual window 116. A dose display element 250 of the syringe driving assembly 100 may be presented in the visual window 116, which will be described in detail below.

[0103] As shown in Figs. 5a to 5c, the inner housing 130 may include a cylindrical portion 131 at its proximal end (being the “lower end” in Figs. 5a and 5b) and a top wall 132 at a distal end (being the “upper end” in Figs. 5a and 5b) opposite to the proximal end. The cylindrical portion 131 and the top wall 132 may be connected to each other through two or more connecting pieces 133, which may extend between the cylindrical portion 131 and the top wall 132 and be spaced apart from each other in a circumferential direction of the cylindrical portion 131. In the embodiment shown in Figs. 5a to 5c, two connecting pieces 133 are provided, which are spaced apart from each other by 180 degrees. In some embodiments, in order to increase the strength of the connecting pieces 133, one or more annular connectors 134 for connecting the two or more connecting pieces 133 may be further provided between the cylindrical portion 131 and the top wall 132. In some embodiments, an inner surface of each connecting piece 133 may be provided with a rib 147 extending along part of a length of the connecting piece 133. The rib 147 may be used to guide the driving mechanism 150 and prevent the driving mechanism 150 from rotating inside the inner housing 130, which will be described in detail below.

[0104] When the inner housing 130 is fixed inside the outer housing 110, the cylindrical portion 131 of the inner housing 130 can protrude from the proximal end of the outer housing 110 (as shown in Fig. 1c). The cylindrical portion 131 may be provided with an L- shaped connecting groove 135, which may include a first open groove extending along an axial direction of the cylindrical portion 131 and a second groove connected with the first groove and extending along a circumferential direction of the cylindrical portion 131. The cylindrical portion 131 may be inserted into a housing of the syringe retaining 1assembly 300 (as shown in Figs. 21a and 21b) and can connect the syringe driving assembly 100 with the syringe retaining assembly 300 via snap-fitting of the L-shaped connecting groove 135 with a connecting protrusion 311 provided inside the housing 310 of the syringe retaining assembly 300. In other embodiments, the cylindrical portion 131 may not include the L-shaped connecting groove 135, for example, the cylindrical portion131 may include a thread provided on an outer surface thereof, thereby forming a threaded connection with the housing of the syringe retaining assembly 300. Other connection means may also be envisaged.

[0105] The guide grooves 136 may be provided on the outer surface of the cylindrical portion 131 of the inner housing 130 and on an outer surface of the at least one annular connector 134. As mentioned above, upon insertion of the inner housing 130 into the outer housing 110, the guide grooves 136 may receive the ribs 115 provided on the inner surface of the body 111 of the outer housing 110 and allow the ribs 115 to slide therein, so as to guide the insertion of the inner housing 130 and prevent the inner housing 130 from rotating inside the outer housing 110.

[0106] With continued reference to Figs. 5a and 5b, in an embodiment according to the present disclosure, the top wall 132 may be used to support a first driving spring 151 of the driving mechanism 150 (as shown in Fig. 7) to be described in detail below. A distal end of the first driving spring 151 may be abutted against the top wall 132. The top wall132 may include a hole 137 through the top wall 132. The hole 137 may allow a spring strut 170 (to be described in detail below) of the driving mechanism 150 for retaining the first driving spring 151 to extend through. In the embodiment shown in Figs. 5a and 5b, below the top wall 132 may also be provided a spring strut 138 suspended from the top wall 132. The first driving spring 151 of the driving mechanism 150 may be fitted over the spring strut 138. The spring strut 138 may include an inner cavity 139 communicatingwith the hole 137 of the top wall. The spring strut 170 of the driving mechanism 150 may extend through the inner cavity 139 of the spring strut 138 of the inner housing 130 and protrude out of the hole 137 of the top wall 132. In order to facilitate the insertion of the spring strut 170 of the driving mechanism 150, the spring strut 138 of the inner housing 130 may include a plurality of elastic fingers 140, which may be distributed around the inner cavity 139.

[0107] In the embodiment shown in Figs. 5a to 5c, a locking element mounting portion 141, where a locking element 190 (as shown in Figs. 12a and 12b) for releasably locking the driving mechanism 150 is to be mounted, may be provided above the top wall 132. The locking element mounting portion 141 may include two legs 142 and a space 143 between the two legs 142. The locking element 190 shown in Figs. 12a and 12b may be positioned within the space 143. The two legs 142 may each have a stop lug 144 extending outward in a direction perpendicular to the two legs 142. The stop lugs 144 may be in interference with the limiting element 113 of the outer housing 110 to prevent the inner housing 130 from moving out of the distal end of the outer housing 110.

[0108] A shaft portion 145 may be disposed above the locking element mounting portion 141. As described above, the shaft portion 145 can protrude from the distal end of the outer housing 110 through the opening 114 of the limiting element 113 of the outer housing 110, so as to cooperate with the fastening element to fasten the outer housing 110 and the inner housing 130 together. The shaft portion 145 may be provided with a cavity 146, and the fastening element 30 shown in Figs. 6a and 6b may extend into the cavity 146 and be snap-connected with the shaft portion 145, thereby fastening the outer housing 110 and the inner housing 130 together. Specifically, as shown in Figs. 6a and 6b, the fastening element 30 may include a circular base portion 31 and a rod portion 32 extending from the base portion 31 towards one side. A free end of the rod portion 32 isprovided with a tapered head portion 33 in the shape of a mushroom, wherein the tapered head portion 33 includes a snap portion 34 having a diameter larger than that of the rod portion 32. After the tapered head portion 33 of the fastening element 30 extends into the cavity 146 of the shaft portion 145, the snap portion 34 of the head portion 33 can form a snap-fitting with the proximal end surface of the cavity 146, thereby achieving a snap connection with the shaft portion 145. In order to enable the head portion 33 of the fastening element 30 to extend into the cavity 146 more easily, the rod portion 32 of the fastening element 30 may be configured to be formed of two elastic fingers spaced apart from each other. Inside the cavity 146, the two elastic fingers can be elastically deformed to approach each other, while after the head portion 33 of the fastening element 30 extends beyond the cavity 146 and goes out of the proximal end of the cavity 146, the two elastic fingers may return to their original shapes. In other embodiments, the rod portion 32 of the fastening element 30 may be formed of only a single element, and in this embodiment, the head portion 33 of the fastening element 30 may be configured as a compressible and resilient elastic portion. In addition, in the embodiment shown in Figs. 5a and 5b, an outer periphery of the shaft portion 145 is provided with external threads, but the present disclosure is not limited to this, and the outer periphery of the shaft portion 145 may not include external threads.

[0109] Referring to Figs. 7 to 12d, the specific structure of the driving mechanism 150 of the syringe driving assembly 100 will be described in detail.

[0110] The driving mechanism 150 may include a movable body 160 that can move after the driving mechanism is released, a first driving spring 151 and a second driving spring 152. In embodiments according to the present disclosure, the second driving spring 152 may be configured to drive the barrel 21 of the syringe 20 to move proximally to insert the needle of the syringe 20 into an injection site of a target, while the first driving spring151 may be configured to drive the movable plunger rod 22 of the syringe 20 to move proximally to perform injection (i.e. , injecting the fluid in the barrel 21 of the syringe 20 into an injection site of a target through the needle). As shown in Fig. 7, the first driving spring 151 and the second driving spring 152 may be configured as compressible coil springs, wherein when the first driving spring 151 and the second driving spring 152 are compressed, the first driving spring 151 and the second driving spring 152 accumulate elastic potential energy; and after the driving mechanism 150 is released, the first driving spring 151 and the second driving spring 152, which have accumulated elastic potential energy, can extend proximally to drive the movable plunger rod 22 and the barrel 21 of the syringe 20 to move proximally, respectively.

[0111] Referring to Figs. 8a and 8b, the movable body 160 of the driving mechanism 150 may include two energy storage rods 161 spaced apart from each other, and a connecting element 162 for fixedly connecting the two energy storage rods 161. The two energy storage rods 161 are configured to enable the movable body 160 to be movable distally, so as to compress the first driving spring 151 and the second driving spring 152 to accumulate elastic potential energy respectively. An outer surface of each energy storage rod 161 (i.e., the surface facing away from the other energy storage rod 161) may be provided with a guide groove 166 extending between a proximal end and a distal end of the energy storage rod 161. When the movable body 160 of the driving mechanism 150 is mounted inside the inner housing 130, the guide groove 166 can receive the rib 147 provided on the inner surface of each connecting piece 133 of the inner housing 130 and enable the movable body 160 of the driving mechanism 150 to move along the rib 147. A portion of the guide groove 166 can penetrate through the thickness of the energy storage rod 161 to thereby form a through groove 167, with a closed end surface 168 being formed at the proximal end of the energy storage rod 161. The distal end of each energy storagerod 161 is provided with a hook portion 169 extending outward. The hook portion 169 may be hooked against a top portion of the rib 147 of each connecting piece 133 to define the maximum distance that the movable body 160 moves proximally relative to the inner housing 130 and prevent the movable body 160 from moving out of the proximal end of the inner housing 130.

[0112] The connecting element 162 may be disposed near the distal ends of the two energy storage rods 161. The connecting element 162 may include a bottom wall 163, and a connecting plate such as an arc-shaped connecting plate 164 that extends distally from a substantially outer periphery of the bottom wall 163. The arc-shaped connecting plate 164 is fixedly mounted between the two energy storage rods 161. An outer peripheral surface of the arc-shaped connecting plate 164 may be provided with two dose control elements 165 spaced apart from each other for controlling the moving distance of the movable body 160 of the driving mechanism 150, thereby controlling the injected dose. One of the dose control elements 165 may be provided with an injection indication mark 1650 for indicating whether the injection is completed or not. The injection indication mark 1650 may be displayed in the visual window 116 of the body 111 of the outer housing 110.

[0113] The movable body 160 may further include the spring strut 170 extending distally from a substantially central position of the bottom wall 163 of the connecting element 162. As shown in Fig. 8c, the first driving spring 151 may be fitted over the spring strut 170 and a proximal end of the first driving spring 151 may be abutted against the bottom wall 163. When the movable body 160 is moved distally by pushing the two energy storage rods 161, the bottom wall 163 can compress the first driving spring 151 to allow it to accumulate elastic potential energy. A distal end of the spring strut 170 may be provided with a hook portion 171. After the movable body 160 of the driving mechanism150 is moved distally to a predetermined position, the locking element 190 shown in Figs.12a and 12b may releasably hook the hook portion 171 of the spring strut 170 (as shown in Fig. 11) to lock the driving mechanism 150 inside the inner housing 130. The locking element 190 can be unlocked to release the driving mechanism 150. After the driving mechanism 150 is released, the first driving spring 151, which has accumulated elastic potential energy, can extend proximally to drive, via the bottom wall 163, the movable body 160 to move proximally.

[0114] The movable body 160 may further include a first driving element 172 extending proximally from the bottom wall 163 of the connecting element 162. The first driving element 172 may be configured to be substantially cylindrical. The first driving element 172 may include a proximal end surface 173. The proximal end surface 173 may be abutted against the flange 23 of the movable plunger rod 22 of the syringe 20 to move the movable plunger rod 22 proximally under the drive of the first driving spring 151 after the driving mechanism 150 is released, to carry out injection.

[0115] Referring to Figs. 9a and 9b and Figs. 10a and 10b, the driving mechanism 150 may further include a first retaining element 175 and a second retaining element 176 for retaining the second driving spring 152. The first retaining element 175 and the second retaining element 176 can retain the second driving spring 152 near the proximal ends of the two energy storage rods 161 (as shown in Figs. 7 and 11).

[0116] As shown in Figs. 9a and 9b, the first retaining element 175 may include a bottom wall 177. A distal end surface 1771 of the bottom wall 177 may be abutted against the proximal end of the second driving spring 152, while a proximal end face 1772 of the bottom wall 177 may be abutted against the flange 26 of the barrel 21 of the syringe 20, such that the barrel 21 can be moved proximally under the drive of the second driving spring 152 after the driving mechanism 150 is released, thereby fulfilling insertion of theneedle of the syringe 20 into an injection site of a target. An outer periphery of the bottom wall 177 may be provided with two ribs 179 facing each other. The two ribs 179 may be placed in the through grooves 167 of the two energy storage rods 161, respectively. A proximal end surface 1791 of each rib 179 may be abutted against the closed end surface 168 of the through groove 167 of the energy storage rod 161, so that when the energy storage rod 161 move distally, the first retaining element 175 is also moved distally to compress the second driving spring 152. The first retaining element 175 may further include a plurality of fingers 180 extending distally from the bottom wall 177. Each finger 180 includes a hook portion 181 extending radially outward. When the driving mechanism 150 is released and the first retaining element 175 moves proximally by a predetermined distance, the hook portions 181 may be hooked against the cylindrical portion 131 of the inner housing 130 to prevent the first retaining element 175 from moving out of the inner housing 130. The bottom wall 177 may also include an opening 182. The first driving element 172 of the movable body 160 can move through the opening 182 to drive the movable plunger rod 22 of the syringe 20.

[0117] The second retaining element 176 may be fixed inside the inner housing 13. As shown in Figs. 10a and 10b, the second retaining element 176 may include a bottom wall 183 for abutting against the distal end of the second driving spring 152 and a plurality of ribs 184 extending proximally from the bottom wall 183. The bottom wall 183 of the second retaining element 176 prevents the second driving spring 152 from moving distally. Two ribs facing each other of the plurality of ribs 184 of the second retaining element 176 may be placed in the through grooves 167 of the two energy storage rods 162, so that after the driving mechanism 150 is released, the movable body 160 of the driving mechanism (including the two energy storage rods 161) can move axially relative to the second retaining element 176. Likewise, the bottom wall 183 of the secondretaining element 176 may further include an opening 186. The first driving element 172 of the movable body 160 can move through the opening 186 to drive the movable plunger rod 22 of the syringe 20.

[0118] In an embodiment according to the present disclosure, the first driving spring 151 and the second driving spring 152 are configured to have different spring stiffnesses, so that the first driving spring 151 and the second driving spring 152, which have accumulated elastic potential energy, can generate driving forces of different magnitudes and thus different driving speeds after being released. In some cases, it is desired that the needle of the syringe be inserted into an injection site of a target at a relatively high speed to alleviate the pain of the target, and the syringe have a relatively low injection speed to meet the injection requirements. Therefore, the first driving spring 151 according to the present disclosure may have a spring stiffness lower than that of the second driving spring 152, which enables the automatic injection device according to the present disclosure to produce a better injection experience and injection effect. However, the present disclosure is not limited to this. As required (for example, in some cases, it may be desired that the needle be inserted into the target at a relatively low speed to protect the needle and the syringe have a relatively high injection speed to complete the injection as soon as possible), the first driving spring 151 may also have a spring stiffness higher than that of the second driving spring 152. By providing a first driving spring and a second driving spring for the driving mechanism 150 according to the present disclosure and selecting different spring stiffnesses for the first driving spring and the second driving spring according to actual conditions, not only the universality of the driving mechanism 150 can be improved, but also the needle insertion speed and injection speed of the syringe can be well balanced.

[0119] As mentioned above, the driving mechanism 150 can be releasably locked inside the inner housing 130 via the locking element 190. Figs. 12a and 12b illustrate the specific structure of the locking element 190 according to an embodiment of the present disclosure. In this embodiment, the locking element 190 may be configured as a spring- loaded pivotable locking element. The locking element 190 may include a locking body 191, a torsion spring 192 for spring-loading the locking body 191, and a pivoting shaft 193 for installation of the torsion spring 192 and allowing the locking body 191 to pivot about it. As shown in Figs. 12c and 12d, the locking element 190 may be mounted in the space 143 of the locking element mounting portion 141 of the inner housing 130, and both ends of the pivoting shaft 193 may be fixed to the two legs 142 of the locking element mounting portion 141, respectively.

[0120] The locking body 191 may include two legs 194. The two legs may be positioned at an angle to each other, for example, in a substantially L-shaped arrangement. An end portion of one of the legs 194 of the locking body 191 may include a first protrusion 195 and a second protrusion 196 extending towards both sides respectively in a direction substantially perpendicular to both of the extending direction of the leg 194 and the extending direction of the pivoting shaft 193. As shown in Fig. 11, the first protrusion 195 may be formed as, for example, a hook-shaped locking portion for releasably hooking the hook portion 171 of the spring strut 170 of the driving mechanism 150 to lock the driving mechanism 150 inside the inner housing 130. The second protrusion 196 may be formed as an unlocking portion. When the second protrusion 196 is pushed distally, the locking body 191 may pivot about the pivoting shaft 193 to disengage the first protrusion 195 from the hook portion 171 of the spring strut 170, thereby releasing the driving mechanism 150.

[0121] Referring to Figs. 13a to 13c, in an embodiment according to the present disclosure, an unlocking element (e.g., an unlocking lever 40) may be used to unlock the locking element 190. Specifically, the unlocking lever 40 may include an elongated body 41 and an abutting portion 42 provided at a distal end of the elongated body 41. When the unlocking lever 40 is pushed distally, the abutting portion 42 of the unlocking lever 40 may be abutted against the second protrusion 196 of the locking body 191 and push the second protrusion 196 (as shown in Fig. 13c), so that the locking body 191 pivots about the pivoting shaft 193 to disengage the first protrusion 195 from the hook portion 171 of the spring strut 170. In an embodiment according to the present disclosure, the unlocking lever 40 may further include a spring element 43. In an initial state, the spring element 43 biases the unlocking lever 40 proximally to prevent the unlocking lever 40 from accidentally unlocking the locking element 190.

[0122] Referring to Fig. 14, in an embodiment according to the present disclosure, the syringe driving assembly 100 may further include a dose adjusting mechanism 200 for adjusting and setting a desired dose of fluid injected by the automatic injection device into a target. The dose adjusting mechanism 200 may include an adjusting gear 210, a driven gear assembly 220 in meshed connection with the adjusting gear 210, a screw 230 connected to the driven gear assembly 220 and including a threaded section, and an adjusting nut 240 fitted over the threaded section of the screw 230 in an axially movable manner.

[0123] As shown in Figs. 15a and 15b, the adjusting gear 210 may be configured as a cylinder, which may include an outer peripheral surface 211 and an inner peripheral surface 212. The inner peripheral surface 212 of the adjusting gear 210 is provided with internal teeth for meshed connection with external teeth provided on an outer surface of the driven gear assembly 220 to thereby drive the driven gear assembly 220 to rotate. Theouter peripheral surface 211 of the adjusting gear 210 may be provided with a plurality of ribs 213 for increasing the roughness of the outer peripheral surface 211 of the adjusting gear 210, so that the adjusting gear 210 can be rotated more easily by the user to perform adjustment. The adjusting gear 210 may be rotatably mounted on the distal portion of the outer housing 110 of the syringe driving assembly 100 by use of the fastening element 30 shown in Figs. 6a and 6b. In order to facilitate installation of the adjusting gear 210, the adjusting gear 210 may include a bottom wall 214 provided at an end, and the bottom wall 214 includes an opening 215, a diameter of which may be larger than that of the rod portion 32 of the fastening element 30 but smaller than that of the base portion 31 of the fastening element 30, so that only the rod portion 32 of the fastening element 30 can extend through the opening 215 to connect the adjusting gear 210, the outer housing 110 and the inner housing 130 together.

[0124] Referring to Fig. 16a, the driven gear assembly 220 may include a driven gear221 and an extension rod 222 fixedly connected with the driven gear 221. The outer peripheral surface of the driven gear 221 is provided with external teeth for meshed connection with the internal teeth on the inner peripheral surface 211 of the adjusting gear 210. When the adjusting gear 210 rotates, the driven gear 221 together with its extension rod 222 may be rotated accordingly. The driven gear 221 and the extension rod222 may be formed as two independent components or may be formed integrally. The extension rod 222 includes a cavity 223 for receiving at least a portion of the screw 230. The cavity 223 of the extension rod 222 may be of a non-circular shape (for example, oval, polygonal, or other irregular shapes).

[0125] Referring to Fig. 16b, the screw 230 may include a threaded section 231, a first section 232 located at a first side (i.e., a distal side) of the threaded section 231 and configured to be inserted into the cavity 223 of the extension rod 222, and a second section233 located at a second side (i.e., a proximal side) of the threaded section 231. The first section 232 of the screw 230 may have a non-circular shape matching with the cavity 223 of the extension rod 222, so that after the first section 232 is received in the cavity 223 of the extension rod 222, the screw 230 cannot rotate relative to the extension rod 222 but only rotate together with the extension rod 222.

[0126] In an embodiment according to the present disclosure, the first section 232 of the screw 230 is configured to be axially movably inserted into the cavity 223 of the driven gear assembly 220 (referring to Fig. 16c), and a proximal end of the second section 233 of the screw 230 is configured to be always abutted against a selected component of the syringe retaining assembly 300 (for example, an abutting portion 333 of the syringe retaining element 331 to be described below) (referring to Fig. 2b). By such configuration, no matter whether the selected component moves or not (for example, moving to positions corresponding to different needle insertion depths) during operation (for example, during needle insertion), the dose adjusting mechanism 200 always takes the position where the selected component is located after the needle is inserted into the target, as a reference point or an injection zero point (since the axial movement of the screw 230 can automatically compensate for the moving distance of the selected component), so that the to-be-injected dose having been adjusted is not affected by any change of the position of the selected component. An elastic pressing element (for example, a compressible coil spring) may be provided in the cavity 223 of the driven gear assembly 220, so that the proximal end of the second section 233 of the screw 230 is always abutted against the selected component.

[0127] The adjusting nut 240 is fitted over the threaded section 231 of the screw 230, so that the adjusting nut 240 can move axially along the threaded section 231 of the screw 230 when the screw 230 rotates. As shown in Fig. 17, the adjusting nut 240 may includetwo stop portions 241 extending oppositely along the radial direction of the adjusting nut240. When assembled in the automatic injection device 10, the screw 230 may be disposed between the two dose control elements 165 shown in Fig. 7, and the adjusting nut 240 is positioned at a proximal side of the dose control elements 165 (as shown in Fig. 2b). After the adjusting nut 240 is adjusted to an appropriate injection dose position, the movable body 160 of the driving mechanism 150 moves proximally until the two dose control elements 165 of the movable body 160 are respectively abutted against the two stop portions 241 of the adjusting nut 240. At this time, the movable body 160 can no longer move proximally and the automatic injection device 10 completes the injection of a predetermined dose.

[0128] In an embodiment according to the present disclosure, the adjusting nut 240 may further include an adjusted-dose indicating element 242. The adjusted-dose indicating element 242 may be configured as a protrusion extending in a direction substantially perpendicular to the extending direction of the two stop portions 241. The adjusted-dose indicating element 242 may be used in conjunction with the dose display element 250 shown in Fig. 18. The dose display element 250 may include a rectangular body 251 and an elongated opening 252 provided in the rectangular body 251. The dose display element 250 may be positioned on the threaded section 231 of the screw 230 in a manner of not interfering with the rotation of the screw 230. The adjusted-dose indicating element 242 of the adjusting nut 240 may be exposed from the elongated opening 252 of the dose display element 250 and is movable inside the elongated opening 252. The rectangular body 251 of the dose display element 250 may include a plurality of dose display scales 253, such as a plurality of dose display scales for displaying 0 ml to 1.0 ml. The adjusted- dose indicating element 242 of the adjusting nut 240 may be adjusted to align with one of the dose display scales to set the desired injection dose, which is helpful for convenientoperation. In order to facilitate the observation of the preset injection dose, as described above and as shown in Fig. 19, the entire dose display element 250 may be presented in the visual window 116 of the outer housing 110 of the syringe driving assembly 100. In addition, as mentioned above, in the embodiment where the first section 232 of the screw 230 is configured to be axially movably inserted into the cavity 223 of the driven gear assembly 220, the dose display element 250 can move inside the visual window 116 along with the movement of the screw 230. Therefore, it is particularly advantageous that the length of the visual window 116 may be set to be larger than that of the dose display element 250, so that the dose display element 250 can always be presented in the visual window 116.

[0129] The dose adjusting mechanism 200 according to the present disclosure can perform adjustment in the following manner to reach the desired injection dose: the adjusting gear 210 is rotated in a predetermined direction so that the driven gear assembly 220 and the screw 230 connected therewith are rotated accordingly; the rotation of the screw 230 causes the adjusting nut 240 to move axially on the threaded section 231 of the screw 230 until the adjusting nut 240 moves to the desired injection dose.

[0130] Next, referring to Figs. 20a to 29b, the specific structure of the syringe retaining assembly 300 will be described in detail.

[0131] The syringe retaining assembly 300 may include a housing 310 (see Figs. 21a to 21c) and a syringe retaining mechanism 330 (see Fig. 22) accommodated in the housing 310. The housing 310 may be substantially cylindrical. A distal end of the housing 310 may be configured to have substantially the same shape as the proximal end of the outer housing 110 of the syringe driving assembly 100, and may receive the cylindrical portion 131 of the inner housing 130 of the syringe driving assembly 100. An inner surface of the housing 310 is provided with one or more connection protrusions 311 at a position nearthe distal end of the housing 310. The connection protrusions 311 can get access into theL-shaped connecting groove 135 of the inner housing 130 of the syringe driving assembly 100 to form a snap-fitting thereby to connect the syringe driving assembly 100 and the syringe retaining assembly 300 with each other. The proximal end of the housing 310 may be provided with a proximal flange 312 extending radially inward for preventing the syringe retaining mechanism 330 from moving out of the proximal end of the housing 310. In some embodiments, the housing 310 may further include an observation window 316 to allow the user to observe the injection process. Compared with the other existing automatic injection devices, the automatic injection device 10 according to the present disclosure can have better visibility.

[0132] As shown in Fig. 22, the syringe retaining mechanism 330 may include a syringe retaining element 331 for retaining the syringe 20, and a needle shielding element 350 for shielding the needle of the syringe 20 when injection is not performed. A compressible coil spring 351 may be disposed between the syringe retaining element 331 and the needle shielding element 350. In the initial state, the coil spring 351 is in an extended state, enabling the needle shielding element 350 to shield the needle of the syringe 20; while in the compressed state, the coil spring 351 may be contracted so the needle of the syringe 20 can protrude from the needle shielding element 350 and be inserted into the injection site of the target.

[0133] As shown in Figs. 23a and 23b, the syringe retaining element 331 may be configured as a retaining sleeve having a cavity 337. The syringe 20 may be accommodated in the retaining sleeve. The syringe retaining element 331 may include a distal flange 332, and the flange 26 of the barrel 21 of the syringe 20 may be abutted against at least a portion of the distal flange 332 of the syringe retaining element 331 (as shown in Fig. 29b), so that the syringe 20 cannot extend out of the cavity 337 of thesyringe retaining element 331. The distal flange 332 of the syringe retaining element 331 may be provided with an abutting portion 333. The proximal end of the second section 233 of the screw 230 of the dose adjusting mechanism 200 may be abutted against the abutting portion 333 (as shown in Fig. 2b).

[0134] The syringe retaining element 331 may also include a proximal flange 334. The distal end of the coil spring 351 may be abutted against the proximal flange 334 of the syringe retaining element 331. Between the distal flange 332 and the proximal flange 334 of the syringe retaining element 331, two intermediate flanges 335 may also be provided. The two intermediate flanges 335 are spaced apart at a certain distance along the extending direction of the syringe retaining element 331, and the two intermediate flanges 335 may have substantially the same structure.

[0135] As shown in Fig. 24, the needle shielding element 350 may have a cylindrical body 352 with two open ends. When no injection is performed, the needle of the syringe 20 can be shielded by the cylindrical body 352 to prevent accidental needle-stick injury. A distal end of the cylindrical body 352 may comprise a first flange 353. A proximal end of the coil spring 351 may be abutted against the first flange 353 of the cylindrical body 352. In the embodiment shown in Fig. 24, the cylindrical body 352 may further include a second flange 354 spaced apart from the first flange 353 at a certain distance. The second flange 354 may be abutted against the proximal flange 312 of the housing 310, so that the needle shielding element 350 as well as the entire syringe retaining mechanism 330 cannot move out of the proximal end of the housing 310. In some embodiments, the cylindrical body 352 may not include the second flange 354; instead, a proximal surface of the first flange 353 is made to be abutted against the proximal flange 312 of the housing 310 to thereby prevent the needle shielding element 350 as well as the entire syringe retaining mechanism 330 from moving out of the proximal end of the housing 310.

[0136] The needle shielding element 350 may further include an elongated trigger element 355 (e.g., an elongated trigger sheet) extending distally from the first flange 353 of the cylindrical body 352. A distal end of the elongated trigger element 355 may be aligned with the proximal end of the unlocking lever 40 shown in Fig. 13a (as shown in Fig. 2a), so that when the needle shielding element 350 together with its elongated trigger element 355 moves distally, the elongated trigger element 355 can be abutted against and push the unlocking lever 40 distally to unlock the locking element 190. After the locking element 190 is unlocked, the driving mechanism 150 of the syringe driving assembly 100 can be released to automatically insert the needle of the syringe 20 into an injection site of a target and automatically inject the fluid in the syringe 20 into the target at a predetermined dose. However, it should be noted that in the initial state, the distal end of the elongated trigger element 355 is spaced apart from the proximal end of the unlocking lever 40 shown in Fig. 13a at a certain distance, so that the unlocking lever 40 may not be moved during the initial movement of the needle shielding element 350 and the elongated trigger element 355, and only after the needle shielding element 350 moves a sufficient predetermined distance towards the injection site of the target, the elongated trigger element 355 is abutted against and push the unlocking lever 40 distally. In addition, in order not to interfere with the elongated trigger element 355 of the needle shielding element 350, the intermediate flanges 335 of the syringe retaining element 331 may each be provided with an opening 336, as shown in Figs. 22 and 23a. The elongated trigger element 355 of the needle shielding element 350 can extend through the opening 336.

[0137] In an embodiment according to the present disclosure, the syringe retaining mechanism 330 may include a depth adjusting mechanism 340 for adjusting the insertion depth of the needle. The depth adjusting mechanism 340 may be disposed or mounted onthe syringe retaining element 331, and may include a depth adjusting element 341 and a depth limiting element 342 used in cooperation with the depth adjusting element 341.

[0138] In an embodiment according to the present disclosure, the depth limiting element 342 may be configured as a stopper (for example, a stopping rib shown in Fig. 23b) fixedly provided on the syringe retaining element 331, and may be provided in the vicinity of and below the distal intermediate flange of the two intermediate flanges 335 of the syringe retaining element 331.

[0139] As shown in Figs. 25a and 25b, the depth adjusting element 341 may include a body 343. The body 343 may have a substantially circular arc shape, so that it can be snugly disposed on the syringe retaining element 331. The body 343 may be mounted on the syringe retaining element 331 in a snap-fit manner by use of a mounting element 60 shown in Fig. 26 and is located at a proximal side of the depth limiting element 342 (below the depth limiting element 342 as shown in Fig. 22). The body 343 is mounted to be rotatable about the syringe retaining element 331, and is mounted to allow the syringe retaining element 331 to move axially relative to the body 343 of the depth adjusting element 341 (i.e., the axial movement of the body 343 is not restricted). In the initial state, as shown in Fig. 22, the body 343 may be supported on the proximal intermediate flange of the two intermediate flanges 335 of the syringe retaining element 331.

[0140] A distal end of the body 343 of the depth adjusting element 341 is provided with a plurality of steps 344, such as four steps shown in Fig. 25a. The plurality of steps 344 have different heights (for example, gradually decreasing heights as shown in Fig. 25a), so that the insertion depth defined by each step 344 is different from that defined by the other steps 344, when cooperating with the depth limiting element 342. Specifically, the initial spacing distance between each step 344 and the depth limiting element 342 may correspond to the insertion depth of the needle. As the plurality of steps 344 have differentheights, the initial spacing distances between the plurality of steps 344 and the depth limiting element 342 all differ from each other. Upon adjustment, the body 343 of the depth adjusting element 341 may be rotated to align one of the steps 344 with the depth limiting element 342, thereby selecting a desired insertion depth. During insertion of the needle, the driving mechanism 150 of the syringe driving assembly 100 may drive the syringe retaining element 331 together with the syringe 20 therein to move proximally until the depth limiting element 342 is abutted against the step 344 aligned therewith. At this time, the needle is inserted into the target at a desired depth. In addition, in this embodiment and as mentioned above, when the first section 232 of the screw 230 of the dose adjusting mechanism 200 is configured to be axially movably inserted into the cavity 223 of the driven gear assembly 220 and the proximal end of the second section 233 of the screw 230 is configured to be always abutted against the abutting portion 333 of the syringe retaining element 331 of the syringe retaining assembly 300, although the abutting portion 333 of the syringe retaining element 331 may move by different distances at different insertion depths, the dose adjusting mechanism 200 always takes the position where the abutting portion 333 is located after the needle is inserted into the target, as the reference point or the injection zero point, so the to-be-injected dose having been adjusted is not affected by any change of the position of the abutting portion 333.

[0141] In order to facilitate rotation of the body 343 of the depth adjusting element 341 to adjust the insertion depth or select a desired insertion depth, the depth adjusting mechanism 340 may include an operating element 345 (for example, an operating handle shown in Fig. 27). The operating element 345 may be fixedly connected with the body 343 of the depth adjusting element 341. For this purpose, the body 343 of the depth adjusting element 341 may include a mounting portion 346 for installation of the operating element 345. The mounting portion 346 may be formed integrally with the body343 and may have any suitable shape. In addition, returning to Figs. 20a to 21a, in order to expose the operating element 345 for adjustment, the housing 310 of the syringe retaining assembly 300 may be provided with an adjustment opening 313 extending along a circumferential direction of the housing. The operating element 345 may extend out of the adjustment opening 313 and may move in the circumferential direction within the adjustment opening 313 to rotate the body 343 of the depth adjusting element 341. The adjustment opening 313 may be provided with depth indication marks 314 (for example, numbers "4", "5", "6" and "8" shown in Fig. 20a), so that the user can select the desired insertion depth more intuitively.

[0142] Further, as shown in Fig. 28, in an embodiment according to the present disclosure, in order to prevent the syringe retaining mechanism 330 from moving out of the distal end of the housing 310, the syringe retaining assembly 300 may include a limiting element 360. The limiting element 360 may be fixed inside the housing 310 of the syringe retaining assembly 300 at a position near the distal end via a fixing element (e.g., a screw) to limit the syringe retaining mechanism 330 within the housing 310. Figs. 29a and 29b show the cooperation of the limiting element 360 with the syringe retaining mechanism 330.

[0143] Next, referring to Figs. 30 to 36, the specific structure of the needle cap removing assembly 500 will be described in detail.

[0144] In an embodiment according to the present disclosure, the needle cap removing assembly 500 may include a needle cap removing element 510. As shown in Figs. 33a and 33b, the needle cap removing element 510 may include a housing 511 and a needle cap removing member 512 disposed at a central position of the housing 511. The shape of the housing 511 may be adapted to the shape of the proximal portion of the housing 310 of the syringe retaining assembly 300, so that the housing 511 can be fitted over theproximal portion of the housing 310 of the syringe retaining assembly 300 (as shown inFigs, la and Id). The needle cap removing member 512 may include a plurality of elastic fingers 513 distributed along a circumference (for example, four elastic fingers 513 shown in Fig. 33b) and a central cavity 514 surrounded by the plurality of elastic fingers 513. Each elastic finger 513 includes a hook portion 515 extending radially inward. When the needle cap removing assembly 500 is fitted over the automatic injection device equipped with the syringe 20, the needle cap removing member 512 of the needle cap removing element 510 can extend into the needle shielding element 350 shown in Figs. 29a and 29b, and the needle cap 24 of the syringe 20 can extend into the central cavity 514 of the needle cap removing member 512, so that the hook portion 515 of each elastic finger 513 of the needle cap removing member 512 can hook the end surface 25 of the needle cap 24 (see Figs.31 and 32). In this way, when the needle cap removing assembly 500 is removed, the needle cap 24 can be removed from the syringe 20 by means of the hook portions 515 of the needle cap removing member 512. After the needle cap 24 is removed from the syringe 20, injection may be performed. During injection, the needle cap 24 can be held in the needle cap removing assembly 500, which prevents the needle cap 24 from being accidentally discarded, rolling off the workbench, or contaminating other articles.

[0145] In an embodiment according to the present disclosure, in order to prevent the needle cap removing assembly 500 from being accidentally removed from the automatic injection device 10, the needle cap removing assembly 500 may include a snap assembly 520 for releasably snapping the needle cap removing assembly 500 onto the automatic injection device 10 (in particular, snapping the needle cap removing assembly 500 onto the housing 310 of the syringe retaining assembly 300 of the automatic injection device 10).

[0146] As shown in Fig. 34, the snap assembly 520 may include a pair of spring-loaded snap elements 521. Each snap element 521 may have an elongated body, a hook portion 522 disposed at a first end of the body, and a torsion spring 523 disposed at a second end opposite to the first end of the body. The pair of snap elements 521 may be mounted on the housing 511 of the needle cap removing element 510 facing each other. To this end, the housing 511 of the needle cap removing element 510 may include a pair of openings 516 for receiving the pair of snap elements 521. The pair of openings 516 are arranged on both sides of the housing 511 facing each other. The pair of snap elements 521 are arranged in the pair of openings 516 of the housing 511 in a spring-loaded manner, with the hook portions 522 facing the inside of the housing 511 (see Fig. 30). In the initial state, the first ends of the pair of snap elements 521 where the hook portions 522 are located approach each other under the action of the torsion springs 523 (see Fig. 30). When a pressing force is applied to the second ends of the pair of snap elements 521, the pair of snap elements 521 can overcome the elastic force of the torsion spring 523 to move away from each other.

[0147] Accordingly, in order for cooperation with the snap assembly 520, as shown in Figs. 20b and 21c, the housing 310 of the syringe retaining assembly 300 may be provided with a protrusion 315 for cooperation with the hook portion 522 of the snap element 521. When the needle cap removing assembly 500 is fitted over the housing 310 of the syringe retaining assembly 300, the hook portions 522 of the snap elements 521 may be hooked against the protrusions 315, so that the needle cap removing assembly 500 cannot be accidentally removed from the syringe retaining assembly 300. When there is a need to remove the needle cap removing assembly 500 from the syringe retaining assembly 300, the user may actively apply a pressing force to the second ends of the pair of snap elements 521 to make the pair of snap elements 521 move away from each other, whichmay result in disconnection of the hook portions 522 from the protrusions 315. In order to facilitate application of the pressing force, as shown in Figs. 30 and 34, a pressing portion 524 may be provided on an outer side of the second end of each snap element 521. The user may put his fingers on the pressing portions 524 to carry out pressing operation.

[0148] In an embodiment according to the present disclosure, the needle cap removing assembly 500 is further configured to mount the needle cap 24 held therein onto the syringe 20 again after injection, so as to shield the needle of the used syringe 20, which can avoid accidental needle-stick injury that may be caused during the discarding of the used syringe 20. To this end, the needle cap removing assembly 500 may be re-fitted over the housing 310 of the syringe retaining assembly 300 of the automatic injection device 10 to mount the needle cap 24 onto the used syringe 20 again. After the needle cap 24 is mounted on the used syringe 20 again, in order to release the needle cap 24 from the needle cap removing assembly 500, the needle cap removing assembly 500 may be provided with a needle cap releasing assembly 530.

[0149] The needle cap releasing assembly 530 may be configured to at least partially extend into the central cavity 514 of the needle cap removing member 512 of the needle cap removing element 510, and the needle cap releasing assembly 530 may be configured to deflect each elastic finger 513 of the needle cap removing member 512 outward when it moves toward the inside of the needle cap removing element 510, thereby disengaging the hook portion 515 of each elastic finger 513 from the end surface 25 of the needle cap 24 to release the needle cap 24. For this purpose, the housing 511 of the needle cap removing element 510 may be provided with a channel 517 for accommodating the needle cap releasing assembly 530. The channel 517 is configured to lead to the central cavity514, so that the needle cap releasing assembly 530 can at least partially extend into the central cavity 514 via the channel 517.

[0150] Referring to Figs. 34 to 36, in an embodiment according to the present disclosure, the needle cap releasing assembly 530 may include a needle cap releasing element 531, and a retaining element 532 for retaining the needle cap releasing element 531 in the housing 511 of the needle cap removing element 510 (in particular, in the channel 517 of the housing 511) in an axially movable manner.

[0151] As shown in Fig. 35, the needle cap releasing element 531 may include a first section 533 for releasing the needle cap, a second section 534 sleeved with a compressible spring element 535, and a third section 536 for retaining the spring element 535, wherein an outer diameter of the second section 534 is smaller than those of the first section 533 and the third section 536.

[0152] The first section 533 of the needle cap releasing element 531 is configured to at least partially extend into the central cavity 514 of the needle cap removing member 512 of the needle cap removing element 510, and during movement of the first section 533 towards the inside of the needle cap removing element 510, each elastic finger 513 of the needle cap removing member 512 is deflected outward, which results in disengagement of the hook portion 515 of each elastic finger 513 from the end surface 25 of the needle cap 24 to thereby release the needle cap 24.

[0153] In the embodiment shown in Figs. 32 and 35, the first section 533 of the needle cap releasing element 531 is of a cylindrical shape, and includes a first portion 5331 having a first outer diameter and a second portion 5332 having a second outer diameter greater than the first outer diameter. Between the first portion 5331 and the second portion 5332 may be provided an inclined transitional portion 5333. Correspondingly, as shown in Fig. 32, each elastic finger 513 of the needle cap removing member 512 of the needlecap removing element 510 may include a first portion 5131 having a first inner diameter and a second portion 5132 having a second inner diameter smaller than the first inner diameter. In some cases, each elastic finger 513 may further include a third portion 5133 having a third inner diameter smaller than the second inner diameter, and the hook portion 515 may be disposed at an end of the third portion 5133. The second outer diameter of the second portion 5332 of the first section 533 of the needle cap releasing element 531 may be substantially equal to the first inner diameter of the first portion 5131 of each elastic finger 513, and the first outer diameter of the first portion 5331 of the first section 533 of the needle cap releasing element 531 may be substantially equal to the second inner diameter of the second portion 5132 of each elastic finger 513. In the initial state, the second portion 5332 of the first section 533 of the needle cap releasing element 531 only extends into the central cavity surrounded by the first portions 5131 of the plurality of elastic fingers 513, and does not extend into the central cavity surrounded by the second portions 5132 of the plurality of elastic fingers 513. When the needle cap 24 needs to be released, the needle cap releasing element 531 is pushed distally so that the second portion 5332 of the first section 533 of the needle cap releasing element 531 gets access into the central cavity surrounded by the second portions 5132 of the plurality of elastic fingers 513. As the second outer diameter of the second portion 5332 of the first section 533 of the needle cap releasing element 531 is larger than the second inner diameter of the second portion 5132 of each elastic finger 513, the second portion 5332 of the first section 533 of the needle cap releasing element 531 may deflect each elastic finger 513 outward, thereby disengaging the hook portion 515 of each elastic finger 513 from the end surface 25 of the needle cap 24.

[0154] The retaining element 532 may be fitted over the second section 534 of the needle cap releasing element 531. As shown in Fig. 36, the retaining element 532 may include acylindrical body 5321 and a pair of elastic fingers 5322 disposed opposite to each other on the body 5321. Each elastic finger 5322 has a hook portion 5323 extending outward. Correspondingly, as shown in Fig. 33a, a wall surface of the housing 511 of the needle cap removing element 510 that forms the channel 517 is provided with a pair of rectangular openings 518 for cooperation with the hook portions 5323 of the pair of elastic fingers 5322. When the retaining element 532 extends into the channel 517, the hook portions 5323 of the pair of elastic fingers 5322 may be hooked in the pair of rectangular openings 518 to retain the needle cap releasing element 531 in the channel 517 of the housing 511 of the needle cap removing element 510.

[0155] Further, as shown in Fig. 32, the spring element 535 may be located within the retaining element 532 and supported between a bottom wall 5324 of the retaining element 532 and an end surface 5361 of the third section 536 of the needle cap releasing element531. An outer diameter of the third section 536 of the needle cap releasing element 531 is smaller than an inner diameter of the retaining element 532, so that the third section 536 of the needle cap releasing element 531 can also extend into the retaining element532. Accordingly, the needle cap releasing element 531 can move towards the inside of the needle cap removing element 510 to release the needle cap accommodated therein.

[0156] Next, a method for using the automatic injection device 10 according to the present disclosure will be described in detail.

[0157] When automatic injection is required, the use method may include the following steps: a. First, inserting the syringe 20 loaded with fluids such as medication, together with the needle cap 24, into the syringe retaining assembly 300 of the automatic injection device 10, wherein in the case where the automatic injection device 10 includes the needle cap removing assembly 500, the needle cap 24 of the syringe may be inserted into thecentral cavity 514 of the needle cap removing member 512 of the needle cap removing assembly 500, so that the hook portion 515 of each elastic finger 513 of the needle cap removing member 512 is hooked against the end surface of the needle cap 24; b. connecting the syringe retaining assembly 300 and the syringe driving assembly 100; c. adjusting and setting a desired injection dose via the dose adjusting mechanism 200 as required, wherein the dose adjustment is accomplished by rotating the adjusting gear 210 of the dose adjusting mechanism 200 to move the adjusting nut 240 on the screw 230 until the adjusting nut 240 moves to a position corresponding to the desired injection dose; d. adjusting and setting the desired insertion depth of the needle of the syringe in the target via the depth adjusting mechanism 340 as required, wherein the insertion depth adjustment is accomplished by moving the operating element 345 of the depth adjusting mechanism 340 until the operating element 345 is moved to a position corresponding to the desired insertion depth; e. removing the needle cap 24, wherein in the case where the automatic injection device 10 includes the needle cap removing assembly 500, the needle cap 24 is removed by removing the needle cap removing assembly 500 from the automatic injection device 10, and in this case, the removed needle cap 24 is held in the needle cap removing assembly 500; f. abutting the proximal end of the syringe retaining assembly 300 of the automatic injection device 10 against the injection position of the target, and pushing the automatic injection device 10 towards the injection position of the target, wherein in this process, the elongated trigger element 355 of the needle shielding element 350 moves distally and unlocks the locking element 190 of the syringe driving assembly 100, so that the driving mechanism 150 of the syringe driving assembly 100 is released, thereby automaticallyinserting the needle of the syringe 20 into the injection site of the target with the set insertion depth and automatically injecting the fluid in the syringe 20 into the target with the set injection dose via the driving mechanism 150.

[0158] It should be noted that the above steps 1-1) to 1-6) can be implemented in any suitable order, and one or more of the above steps 1-1) to 1-6) may be omitted. For example, either one or both of steps 1-3) and 1-4) may be performed before step 1-1). Alternatively, when no adjustment is required, either one or both of steps 1-3) and 1-4) may be directly omitted.

[0159] After the injection is completed, the needle cap 24 may be fitted over the needle of the syringe 20 again to prevent accidental needle-stick injury. Then, the syringe driving assembly 100 and the syringe retaining assembly 300 may be disconnected to discard the used syringe 20. In the embodiment where the automatic injection device 10 includes the needle cap removing assembly 500, the used syringe 20 may be discarded by the following steps:

[0160] 2-1) mounting the needle cap removing assembly 500 to the proximal end of the syringe retaining assembly 300, so that the needle cap 24 accommodated in the central cavity 514 of the needle cap removing member 512 of the needle cap removing assembly 500 is mounted onto the syringe 20 again;

[0161] 2-2) disconnecting the syringe driving assembly 100 from the syringe retaining assembly 300 and taking the syringe driving assembly 100 away, then grasping the syringe retaining assembly 300 with the syringe 20 facing downward (at this time, the needle cap removing assembly 500 is located above the syringe retaining assembly 300), and placing the syringe retaining assembly 300 over a recycling device (such as a trash can);

[0162] 2-3) moving the needle cap releasing element 531 towards the inside of the needle cap removing element 510 of the needle cap removing assembly 500 (i.e., moving downward) so that each elastic finger 513 of the needle cap removing member 512 is deflected outwards thereby to release the needle cap 24. At this time, the syringe 20 together with the needle cap 24 moves out of the needle cap removing assembly 500 and the syringe retaining assembly 300 by gravity and falls into the recycling device.

[0163] After the used syringe 20 is discarded, the driving mechanism 150 of the syringe driving assembly 100 can be spring-loaded again by pushing the energy storage rods 161 distally (i.e., towards the side where the adjusting gear 210 is mounted). In the process of pushing the energy storage rods 161 distally, the first driving spring 151 is compressed first, and then the second driving spring 152 together with the first driving spring 151 is compressed until the hook portion 171 of the spring strut 170 of the driving mechanism 150 moves to the vicinity of the locking element 190 and is hooked by the first protrusion 195 of the locking element 190. At this time, the driving mechanism 150 of the syringe driving assembly 100 has been loaded. The energy storage rods 161 may be vertically abutted against a solid surface (for example, a horizontal desktop) to push the energy storage rods 161 distally.

[0164] Although the exemplary embodiments of the present disclosure have been described, those skilled in the art should understand that multiple changes and modifications may be made to the exemplary embodiments without substantively departing from the spirit and scope of the present disclosure. Accordingly, all the changes and modifications are encompassed within the protection scope of the present invention as defined by the claims. The present disclosure is defined by the appended claims, and equivalents of these claims are also included in the scope of the present disclosure.

Claims

CLAIMS1. An automatic injection device for automatically injecting a fluid in a syringe into an injection site of a target, the syringe comprising a barrel for containing the fluid, a needle disposed at a proximal end of the barrel, and a movable plunger rod movable axially in the barrel, wherein the movable plunger rod is capable of being driven towards the proximal end of the barrel to inject the fluid in the barrel into the injection site of the target via the needle, wherein the automatic injection device comprises: a syringe retaining assembly for accommodating and retaining the syringe; and a syringe driving assembly including a housing and a driving mechanism releasably disposed in the housing, the driving mechanism including a movable body capable of moving after the driving mechanism is released, a first driving spring, and a second driving spring, wherein the second driving spring is configured to drive the barrel of the syringe to move proximally to insert the needle of the syringe into the injection site of the target, and the first driving spring is configured to drive the movable plunger rod of the syringe to move proximally to perform injection; wherein the first driving spring and the second driving spring have different spring stiffnesses.

2. The automatic injection device according to claim 1, wherein the first driving spring has a spring stiffness smaller than that of the second driving spring.

3. The automatic injection device according to claim 1, wherein the housing of the syringe driving assembly includes an outer housing and an inner housing fixedly positioned inside the outer housing, wherein a distal end of the inner housing is provided with a spring-loaded pivotable locking element configured to releasably lock the driving mechanism in the inner housing.

4. The automatic injection device according to claim 3, wherein the pivotable locking element comprises a locking body, a torsion spring for spring-loading the locking body, and a pivoting shaft for installation of the torsion spring and allowing the locking body to pivot about it, wherein the locking body comprises two legs positioned at an angle to each other, an end portion of a first leg of the two legs includes a first protrusion and a second protrusion extending towards both sides respectively along a direction substantially perpendicular to both of an extending direction of the first leg and an extending direction of the pivoting shaft, wherein a distal end of the movable body of the driving mechanism includes a hook portion, and wherein the first protrusion is formed as a locking portion capable of releasably hooking the hook portion, and the second protrusion is formed as an unlocking portion.

5. The automatic injection device according to claim 4, wherein the movable body of the driving mechanism comprises two energy storage rods spaced apart from each other and a connecting element for fixedly connecting the two energy storage rods, wherein the two energy storage rods are configured to enable the movable body to move distally to compress the first driving spring and the second driving spring to allow them to store elastic potential energy respectively.

6. The automatic injection device according to claim 5, wherein the connecting element is disposed near the distal ends of the two energy storage rods and comprises a bottom wall and a connecting plate extending distally from an outer periphery of the bottom wall, and wherein the movable body comprises a spring strut extending distally from a central position of the bottom wall of the connecting element, the first driving spring is fitted over the spring strut, and the hook portion of the movable body is disposed at a distal end of the spring strut.

7. The automatic injection device according to claim 6, wherein the movable body further comprises a first driving element extending proximally from the bottom wall of the connecting element, and the first driving element is configured to drive the movable plunger rod of the syringe proximally under the driving of the first driving spring.

8. The automatic injection device according to claim 4, wherein the driving mechanism further comprises a first retaining element and a second retaining element for retaining the second driving spring, wherein the first retaining element and the second retaining element retain the second driving spring near proximal ends of the two energy storage rods, and wherein the first retaining element is configured to drive the barrel of the syringe proximally under the driving of the second driving spring after the driving mechanism is released to insert the needle of the syringe into the injection site of the target, and the second retaining element is fixedly disposed in the inner housing.

9. The automatic injection device according to claim 4, wherein the automatic injection device comprises an unlocking lever configured to push the second protrusion of the locking body of the pivotable locking element distally, so that the locking body pivots about the pivoting shaft to disengage the first protrusion from the hook portion of the movable body of the driving mechanism.

10. The automatic injection device according to claim 1, wherein the syringe driving assembly further comprises a dose adjusting mechanism, wherein the dose adjusting mechanism comprises an adjusting gear, a driven gear assembly in meshed connection with the adjusting gear, a screw connected to the driven gear assembly and including a threaded section, and an adjusting nut fitted over the threaded section of the screw in an axially movable manner.

11. The automatic injection device according to claim 10, wherein the driven gear assembly comprises a driven gear, and an extension rod fixedly connected with the drivengear and including a cavity, wherein the screw further comprises a first section located at a distal side of the threaded section and a second section located at a proximal side of the threaded section, and wherein the first section of the screw is configured to be inserted into the cavity of the extension rod in such a way that it is capable of moving axially but unable to rotate relative to the extension rod, while a proximal end of the second section of the screw is configured to be always abutted against a selected component of the syringe retaining assembly.

12. The automatic injection device according to claim 11, wherein an elastic pressing element is provided in the cavity of the driven gear assembly to enable the proximal end of the second section of the screw to be always abutted against the selected component.

13. The automatic injection device according to claim 11, wherein the adjusting gear is configured to be of a cylindrical shape and includes an outer peripheral surface and an inner peripheral surface, wherein the inner peripheral surface of the adjusting gear is provided with internal teeth, and the driven gear is provided with external teeth, and the internal teeth and the external teeth are in meshed connection.

14. The automatic injection device according to claim 10, wherein the movable body of the driving mechanism includes a dose control element, and the adjusting nut is positioned at a proximal side of the dose control element and includes a stopper for stopping the dose control element from moving proximally.

15. The automatic injection device according to claim 14, wherein the adjusting nut further comprises an adjusted-dose indicating element.

16. The automatic injection device according to claim 15, wherein the dose adjusting mechanism further comprises a dose display element including a rectangular body and an elongated opening provided in the rectangular body, wherein the rectangular body is provided with a plurality of dose display scales, and wherein the adjusted-dose indicatingelement is capable of being exposed from the elongated opening and is movable within the elongated opening.

17. The automatic injection device according to claim 16, wherein the housing of the syringe driving assembly has a visual window, in which the dose display element is presented.

18. The automatic injection device according to claim 17, wherein the visual window has a length larger than that of the dose display element.

19. The automatic injection device according to claim 14, wherein the dose control element comprises an injection indication mark for indicating whether injection has been completed.

20. The automatic injection device according to claim 1, wherein the syringe retaining assembly comprises a housing and a syringe retaining mechanism accommodated in the housing of the syringe retaining assembly, wherein the syringe retaining mechanism comprises a syringe retaining element for retaining the syringe, a needle shielding element for shielding the needle of the syringe, and a compressible coil spring disposed between the syringe retaining element and the needle shielding element, and wherein the coil spring has an initial state, in which the coil spring is in an extended state so that the needle shielding element is capable of shielding the needle of the syringe, and a compressed state, in which the coil spring is contracted to allow the needle of the syringe to extend out of the needle shielding element.

21. The automatic injection device according to claim 20, wherein the syringe retaining mechanism further comprises a depth adjusting mechanism for adjusting an insertion depth of the needle of the syringe in the target, the depth adjusting mechanism comprising a depth adjusting element and a depth limiting element, wherein the depth limiting element is configured as a stopper fixedly disposed on the syringe retainingelement, and the depth adjusting element includes a plurality of steps with different heights and is mounted on the syringe retaining element at a proximal side of the depth limiting element in such a way that it is rotatable and does not limit axial movement of the syringe retaining element.

22. The automatic injection device according to claim 20, wherein the needle shielding element of the syringe retaining assembly comprises an elongated trigger element, which is capable of releasing the driving mechanism of the syringe driving assembly after the elongated trigger element moves distally by a predetermined distance.

23. The automatic injection device according to claim 1, wherein the automatic injection device further comprises a needle cap removing assembly having a needle cap removing element, the needle cap removing element including a housing and a needle cap removing member disposed at a central position of the housing of the needle cap removing element, wherein the housing of the needle cap removing element is capable of being fitted over the syringe retaining assembly, and the needle cap removing member is capable of hooking an end surface of the needle cap of the syringe mounted inside the syringe retaining assembly.

24. The automatic injection device according to claim 22, wherein the needle cap removing member comprises a plurality of elastic fingers distributed along a circumference and a central cavity surrounded by the plurality of elastic fingers, wherein each elastic finger comprises a hook portion extending radially inward, and wherein the needle cap of the syringe is capable of extending into the central cavity of the needle cap removing member to allow the hook portion of each elastic finger of the needle cap removing member to hook the end surface of the needle cap.

25. The automatic injection device according to claim 22, wherein the needle cap removing assembly further comprises a snap assembly for releasably snapping the needlecap removing assembly onto the housing of the syringe retaining assembly, the snap assembly comprising a pair of spring-loaded snap elements, and wherein each snap element comprises a hook portion, and the housing of the syringe retaining assembly is provided with a protrusion mated with the hook portion of each snap element.

26. The automatic injection device according to claim 25, wherein each snap element has an elongated body, the hook portion disposed at a first end of the elongated body, and a torsion spring disposed at a second end of the elongated body opposite to the first end, wherein the housing of the needle cap removing element includes a pair of openings, and the pair of snap elements are arranged in the pair of openings in a spring loaded manner respectively, with the hook portions facing inside of the housing of the needle cap removing element.

27. The automatic injection device according to claim 24, wherein the needle cap removing assembly further comprises a needle cap releasing assembly for releasing the needle cap accommodated in the central cavity of the needle cap removing member, the needle cap releasing assembly is configured to at least partially extend into the central cavity of the needle cap removing member, and the needle cap releasing assembly is configured to deflect each elastic finger of the needle cap removing member outward when it moves towards the inside of the needle cap removing element, thereby disengaging the hook portion of each elastic finger from the end surface of the needle cap.

28. The automatic injection device according to claim 27, wherein the needle cap releasing assembly comprises a needle cap releasing element and a retaining element for retaining the needle cap releasing element in the housing of the needle cap removing element in an axially movable manner, wherein the needle cap releasing element comprises a first section for releasing the needle cap, a second section sleeved with acompressible spring element, and a third section for retaining the spring element, the first section being configured to at least partially extend into the central cavity of the needle cap removing member and deflect each elastic finger of the needle cap removing member outward when it moves toward the inside of the needle cap removing element, and wherein the retaining element is fitted over the second section of the needle cap releasing element.

29. The automatic injection device according to claim 28, wherein the retaining element of the needle cap releasing assembly comprises a cylindrical body and a pair of elastic fingers disposed opposite to each other on the cylindrical body, and each elastic finger of the retaining element of the needle cap releasing assembly comprises a hook portion extending outward for retaining the retaining element of the needle cap releasing assembly together with the needle cap releasing element inside the housing of the needle cap removing element.

30. The automatic injection device according to claim 29, wherein the spring element is located within the retaining element of the needle cap releasing assembly and is supported between a bottom wall of the retaining element of the needle cap releasing assembly and an end surface of the third section of the needle cap releasing element.

Images