An automated injection device suitable for pre-filled syringes

Abstract

This invention discloses an automatic injection device suitable for pre-filled syringes, comprising a cap, outer shell, inner shell, inner tube, rotating support, nozzle, needle buckle, piston rod, syringe, first spring, and second spring. The medication is pre-installed in the automatic injection device according to the type and volume of the drug to be injected. In emergencies and harsh environments, it enables self-rescue and mutual rescue for individuals without medical expertise. Larger doses of medication can be administered intramuscularly with a single-person, one-button operation. This invention is not only highly adaptable to various environments (resistant to bumps and contamination), but also has a self-locking function to prevent leakage of the syringe due to improper operation. Furthermore, the automatic injection device is truly unusable after a single injection, avoiding secondary contamination and accidental injury.

Description

Technical Field

[0001] This invention relates to automated injection devices, and more specifically to an automated injection device suitable for pre-filled syringes. Background Technology

[0002] Currently, most commercially available injectable drugs can only be administered by professional medical personnel. Even for professional medical personnel, it is difficult to administer them safely in emergency or harsh environments such as bumpy rides, shaking, or contamination.

[0003] Home-use syringes for hormone medications, such as the "syringe structure" described in Chinese patent CN101282754B, can be used for insulin injection and can be operated by patients or their families. However, these home-use syringes for hormone medications all have short needles, are injected subcutaneously, and are used for very small doses. Furthermore, these syringes do not have a locking or self-explosion function after single use and can be reused, which raises certain safety concerns.

[0004] There is an urgent need in this field to develop an automatic injection device suitable for pre-filled syringes, which can be used for self-rescue and mutual rescue in emergency situations and harsh environments. By adding an automatic injection device to the pre-filled syringe, it is possible to administer intramuscular injections of drugs with a wide range of dosages to people without medical backgrounds. The device can be operated by a single person with one button (including self-injection and injection of others). The device must not only be highly adaptable to the environment (resistant to bumps, pollution, etc.), but also be disposable and cannot be reused to avoid secondary pollution and accidental injury. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides an automated injection device suitable for pre-filled syringes. It features small size, compact structure, and a self-locking function to prevent drug leakage from the syringe due to improper operation. In emergency situations and harsh environments, it can assist personnel without medical expertise in automatically injecting medication.

[0006] The technical solution of the present invention is: an automatic injection device suitable for pre-filled syringes, comprising a cap, an outer shell, an inner shell, an inner tube, a rotating support, a nozzle, a needle tube buckle, a piston rod, a syringe, a first spring, and a second spring;

[0007] The cap includes a cap shell, the top of which is sealed and the bottom opening is open. On the circumferential surface of the cap shell, there are two symmetrical cap limiting planes machined from top to bottom. The bottom end of the cap limiting plane is machined into a cap limiting hook. The hook body of the cap limiting hook protrudes outward and the upper surface is the hook surface.

[0008] The inner center of the top surface of the cap housing is provided with an unlocking cylinder for moving downward to open the piston claw, and the top end of the first spring is located inside the unlocking cylinder.

[0009] The outer shell includes an outer cylindrical shell and an inner cylindrical shell, which are fixedly connected by a support frame. The upper half of the outer cylindrical shell has two symmetrical outer shell limiting planes machined from top to bottom on its circumferential surface. When the cap is inserted into the outer cylindrical shell, the cap limiting plane and the outer shell limiting plane match and fit together to restrict the cap's rotation. At the same time, a cap limiting hook is provided at the corresponding outer shell limiting plane. The hook of the cap limiting hook protrudes inward and its lower surface is the hook surface, so that after the cap limiting hook and the outer shell limiting hook engage, the cap's upward movement is restricted.

[0010] The top of the inner cylindrical tube of the outer shell is provided with a piston claw, which can lock the top of the piston rod and press against the bottom end of the first spring. When the tube cap is inserted into the inner cylindrical tube of the outer shell, the tube cap moves downward under force, and the unlocking cylinder can open the piston claw to release the bottom end of the first spring and the top of the piston rod, so that the bottom end of the first spring is sleeved on the top of the piston rod and pushes the piston rod downward.

[0011] The bottom of the outer shell is also provided with an inner shell positioning corner groove;

[0012] The inner shell is cylindrical in shape. A limiting protrusion is provided on the outer surface of the middle part of the inner shell along the circumferential direction. A positioning corner protrusion of the inner shell is also provided above the limiting protrusion. The part of the inner shell above the limiting protrusion can be fitted and fixed into the outer shell from bottom to top. The positioning corner protrusion and the positioning corner groove of the inner shell can match and fit together.

[0013] The inner shell has a rotating bracket limiting groove and a needle buckle limiting groove machined on the cylindrical part above the limiting protrusion ring; the rotating bracket limiting groove is a slightly curved groove opened along the circumferential direction, and there are two symmetrical grooves on the circumferential surface; the needle buckle limiting groove is an axial groove opened from the top downward, and there are two symmetrical grooves on the circumferential surface.

[0014] The inner shell has symmetrical inner tube track grooves on both sides of the cylindrical part below the limiting protrusion ring, arranged from top to bottom.

[0015] The bottom of the inner shell is also provided with a nozzle snap-fit ​​part;

[0016] The rotating bracket is cylindrical in shape, and symmetrical inner cylinder limiting grooves are provided on two sides of the circumference of the rotating bracket. The inner cylinder limiting groove is composed of an inclined straight groove and a vertical groove. The inclined straight groove is inclined downward at the head end and upward at the tail end. The top end of the vertical groove is connected to the tail end of the inclined straight groove as a whole, and the height of the head end of the inclined straight groove is higher than the height of the bottom end of the vertical groove.

[0017] Two rotating bracket limiting protrusions are symmetrically arranged on the circumferential surface of the rotating bracket. The two rotating bracket limiting protrusions can be embedded in the two rotating bracket limiting grooves in a one-to-one correspondence to restrict the axial movement of the rotating bracket.

[0018] Two needle buckle limiting wing movable grooves are symmetrically opened on the circumferential surface of the rotating bracket, allowing the needle buckle limiting wing of the needle buckle to pass through without restricting the movement of the needle buckle limiting wing;

[0019] The needle tube buckle is ring-shaped and can be fitted onto the top of the syringe to fix the syringe. Symmetrical needle tube buckle limiting wings protrude outward on both sides of the circumference of the needle tube buckle. After passing through the needle tube buckle limiting wing movable groove on the rotating bracket, the two needle tube buckle limiting wings are inserted into the two needle tube buckle limiting grooves one by one to restrict the rotation of the needle tube buckle. After the needle tube buckle that fixes the syringe is installed, the top of the syringe can contact the bottom of the inner cylindrical tube of the outer shell. The piston end of the piston rod fixed in the inner cylindrical tube of the outer shell can extend into the syringe. After the piston rod moves downward, it can squeeze the liquid in the syringe to flow out.

[0020] The inner tube is integrally connected to the upper part, the middle part and the lower part of the inner tube; the upper part of the inner tube includes two symmetrically arranged vertical plates, the bottom of the two vertical plates are connected to form an annular bottom, and each of the two vertical plates is provided with an inner tube limiting protrusion on its outer surface. The two inner tube limiting protrusions can be inserted into the two inner tube limiting grooves on the rotating bracket one by one, and the initial position is located at the head end of the inclined straight groove of the inner tube limiting groove.

[0021] The inner diameter of the middle part of the inner tube is smaller than that of the upper part of the inner tube, so that a stepped surface is formed at the connection between the upper part and the middle part of the inner tube. The second spring is sleeved on the outside of the syringe. The top of the second spring is pressed against the bottom surface of the syringe buckle, and the bottom of the second spring is pressed against the stepped surface. When the inner tube is pushed inward along the axial direction, the second spring is compressed. At the same time, the inner tube body limiting protrusion slides upward in a straight line along the inclined straight groove, and the rotating bracket rotates accordingly. When the inner tube body limiting protrusion reaches the end of the inclined straight groove, it stops, and at the same time, the needle of the syringe inserted in the inner tube is exposed. When the inner tube is released, the second spring is stretched, pushing the inner tube downward. At the same time, the inner tube body limiting protrusion moves downward in a straight line along the vertical groove. When the inner tube body limiting protrusion reaches the bottom of the vertical groove, it stops, and the needle of the syringe is buried in the inner tube again.

[0022] The inner tube is provided with two symmetrical inner tube track sliders on the lower outer surface of the inner tube. The two inner tube track sliders can be fitted into the two inner tube track grooves on the inner shell in a one-to-one correspondence, restricting the inner tube to slide only up and down along the axial direction.

[0023] The nozzle is detachably snapped into the nozzle snap-fit ​​part at the bottom of the inner shell, thus sealing the bottom of the inner shell.

[0024] Furthermore, it also includes a cap locking protection mechanism, which includes two downward-protruding cap limiting posts located at the bottom of the cap housing and two movable grooves for the cap limiting posts located at the top of the rotating bracket.

[0025] When the inner cylinder limiting protrusion is located at the head end of the inclined straight groove of the inner cylinder limiting groove, the bottom surface of the cap limiting post at the bottom of the cap housing abuts against the top of the rotating bracket where there is no movable groove for the cap limiting post, and the cap is restricted and cannot move downward; when the inner cylinder limiting protrusion moves to the tail end of the inclined straight groove, the rotating bracket rotates accordingly, and the movable grooves for the cap limiting posts rotate one by one to below the two cap limiting posts at the bottom of the cap housing, and the cap is unrestricted and can move downward.

[0026] The cap locking mechanism prevents the cap from being pressed under normal placement, thus preventing accidental operation. Only after the nozzle is removed, the inner tube is pressed, and the rotating bracket is in place can the cap be pressed normally, allowing the medication to be injected.

[0027] Furthermore, it also includes an inner tube locking protection mechanism, wherein the inner tube locking protection mechanism is provided with slider protrusions on the two inner tube track sliders and slider protrusion slots on the two inner tube track grooves;

[0028] When the inner tube's limiting protrusion moves downward to the bottom of the vertical groove, the two sliding protrusions engage with their corresponding slots, preventing the inner tube from sliding upward again. This ensures that the inner tube cannot retract after injection, rendering the auto-injector unusable, and the needle is covered internally, protecting personnel from injury during the recovery process.

[0029] Furthermore, the unlocking cylinder is internally provided with a first spring top limiting sleeve and a first spring sleeve rod. The top of the first spring is sleeved on the first spring sleeve rod and located inside the first spring top limiting sleeve to prevent the first spring from slipping off.

[0030] The beneficial effects of this invention are as follows: By selecting a pre-filled needle of appropriate specifications, pre-filling the required medication, and simply adding an automatic injection device to the pre-filled needle, when a person needs to inject the medication, they only need to remove the cap, hold the inner tube perpendicular to the skin at the injection site, and press the inner tube against the skin. The inner tube retracts, exposing the syringe needle. The inner tube drives the rotating support to rotate. Once it reaches the limit position, the needle inserts into the skin. At this point, pressing the cap releases the first spring, which pushes the piston rod, slowly and evenly completing the automatic injection. Afterward, the needle is removed, and the inner tube is released. The inner tube automatically extends, completely covering the needle, protecting the person from injury. At this point, the inner tube is jammed and cannot retract, preventing the automatic injection device from being reused, thus avoiding secondary contamination and accidental injury caused by repeated use.

[0031] The device is small in size and compact in structure, yet its pre-filled capacity is not small. It also features a self-locking function to effectively prevent leakage of the syringe due to improper operation. In emergency situations and under adverse conditions such as shaking, vibration, or contamination, it can achieve single-person, one-button trigger automatic injection, preventing accidental needle injury and contamination to other personnel. Attached Figure Description

[0032] Figure 1(a) is a front view of the overall appearance of the automatic injection device suitable for pre-filled syringes;

[0033] Figure 1(b) is a side view of the overall appearance of the automated injection device suitable for pre-filled syringes;

[0034] Figure 1(c) is a cross-sectional view along the AA direction in Figure 1(b);

[0035] Figure 1(d) is a view of the automatic injection device after the outer shell and inner shell have been removed;

[0036] Figure 1(e) is a schematic diagram of the overall three-dimensional structure of an automatic injection device suitable for pre-filled syringes;

[0037] Figure 2(a) is a top view of the cap;

[0038] Figure 2(b) is a cross-sectional view along the BB direction in Figure 2(a);

[0039] Figure 2(c) is the front view of the cap;

[0040] Figure 3(a) is a front view of the outer shell;

[0041] Figure 3(b) is a cross-sectional view along the AA direction in Figure 3(a);

[0042] Figure 3(c) is a top view of the outer shell;

[0043] Figure 4(a) is a front view of the inner shell;

[0044] Figure 4(b) is a cross-sectional view along the DD direction in Figure 4(a);

[0045] Figure 5 This is a schematic diagram of the rotating support structure;

[0046] Figure 6(a) is a front view of the inner tube;

[0047] Figure 6(b) is a cross-sectional view along the AA direction in Figure 6(a);

[0048] Figure 7(a) is a three-dimensional view of the needle tube buckle;

[0049] Figure 7(b) is a top view of the needle tube buckle;

[0050] Figure 7(c) is a cross-sectional view along the AA direction in Figure 7(b);

[0051] Figure 8(a) is a front view of the nozzle;

[0052] Figure 8(b) is a cross-sectional view of the nozzle;

[0053] Figure 9 This is a schematic diagram of the piston rod structure.

[0054] In the diagram: 1 is the cap, 2 is the outer shell, 3 is the inner shell, 4 is the inner tube, 5 is the rotating bracket, 6 is the nozzle, 7 is the needle tube buckle, 8 is the piston rod, 9 is the syringe, 10 is the first spring, and 11 is the second spring.

[0055] 101 is the cap shell, 102 is the cap limiting plane, 103 is the cap limiting hook, 104 is the unlocking cylinder, 105 is the cap limiting post, 106 is the first spring sleeve rod, and 107 is the first spring top limiting cylinder.

[0056] 201 is the outer cylindrical shell, 202 is the inner cylindrical shell, 203 is the support bridge, 204 is the piston claw, 205 is the outer shell limiting plane, 206 is the outer shell limiting hook, and 207 is the inner shell positioning corner groove.

[0057] 301 is a limiting protrusion ring, 302 is an inner shell positioning corner protrusion, 303 is a rotating bracket limiting groove, 304 is a needle tube buckle limiting groove, 305 is an inner tube track groove, 306 is a slider protrusion groove, and 307 is a nozzle snap-fit ​​part.

[0058] 401 is the upper part of the inner tube, 402 is the middle part of the inner tube, 403 is the lower part of the inner tube, 404 is the inner tube body limiting protrusion, 405 is the inner tube track groove, 406 is the inner tube track slider, and 407 is the slider protrusion.

[0059] 501 is the inner cylinder limiting groove, 502 is the rotating bracket limiting protrusion, 503 is the needle tube buckle limiting wing movable groove, and 504 is the tube cap limiting post movable groove.

[0060] 701 is a needle tube retaining wing;

[0061] 801 is the top of the piston rod, and 802 is the piston end. Detailed Implementation

[0062] The present invention will now be further described with reference to the accompanying drawings.

[0063] As shown in Figures 1(a), 1(b), 1(c), 1(d), and 1(e), an automatic injection device suitable for pre-filled syringes includes a cap 1, an outer shell 2, an inner shell 3, an inner tube 4, a rotating bracket 5, a nozzle 6, a needle tube buckle 7, a piston rod 8, a syringe 9, a first spring 10, and a second spring 11.

[0064] As shown in Figures 2(a), 2(b), and 2(c), the cap 1 includes a cap housing 101. The top of the cap housing 101 seals the bottom opening. Two symmetrical cap limiting planes 102 are machined from top to bottom on the circumferential surface of the cap housing 101. The bottom end of the cap limiting plane 102 is machined into a cap limiting hook 103. The hook of the cap limiting hook 103 protrudes outwards, and its upper surface is a hook surface. An unlocking cylinder 104 for downward movement to open the piston claw is provided at the center of the inner side of the top surface of the cap housing 101. The top end of the first spring 10 is located inside the unlocking cylinder 104. Preferably, the unlocking cylinder 104 contains a first spring top limiting cylinder 107 and a first spring sleeve rod 106. The top of the first spring 10 is sleeved on the first spring sleeve rod 106 and located inside the first spring top limiting cylinder 107 to prevent the first spring from slipping out.

[0065] As shown in Figures 3(a), 3(b), and 3(c), the outer shell 2 includes an outer cylindrical tube 201 and an inner cylindrical tube 202, which are fixedly connected by a support bridge 203. Symmetrical outer shell limiting planes 205 are machined from top to bottom on both sides of the upper half of the outer cylindrical tube 201. When the cap 1 is inserted into the outer cylindrical tube 201, the cap limiting plane 102 and the outer shell limiting plane 205 match and fit together to restrict the cap's rotation. Simultaneously, a cap limiting hook 206 is provided at the corresponding location on the outer shell limiting plane 205. The hook of the cap limiting hook 206 protrudes inwards, and its lower surface is the hook face, allowing the cap limiting hook 103 and the outer shell limiting hook 206 to engage and restrict the cap's upward movement. A piston claw 204 is provided at the top of the inner cylindrical tube 202 of the outer shell. The piston claw 204 can lock the top 801 of the piston rod 8 and can also press against the bottom end of the first spring 10. When the cap 1 is inserted into the inner cylindrical tube 201 of the outer shell, the cap moves downward under force. The unlocking cylinder 104 can open the piston claw 204 to release the bottom end of the first spring 10 and the top 801 of the piston rod, so that the bottom end of the first spring 10 is sleeved on the top 801 of the piston rod and pushes the piston rod 8 downward. The bottom of the outer shell 2 is also provided with an inner shell positioning corner groove 207.

[0066] As shown in Figures 4(a) and 4(b), the inner shell 3 is cylindrical. A limiting protrusion 301 is provided on the outer surface of the middle part of the inner shell 3 along the circumferential direction. Above the limiting protrusion 301, there is also an inner shell positioning corner protrusion 302. The part of the inner shell 3 above the limiting protrusion 301 can be fitted and fixed inside the outer shell 2 from bottom to top, and the inner shell positioning corner protrusion 302 and the inner shell positioning corner groove 207 can match and position. The cylindrical part of the inner shell 3 above the limiting protrusion 301 is machined with a rotating bracket limiting groove 303 and a needle tube buckle limiting groove 304. The rotating bracket limiting groove 303 is a slightly curved groove opened along the circumferential direction, and there are two symmetrical grooves on the circumferential surface. The needle tube buckle limiting groove 304 is an axial groove opened from the top downwards, and there are two symmetrical grooves on the circumferential surface. The inner shell 3 has symmetrical inner tube track grooves 305 arranged from top to bottom on both sides of the cylindrical part below the limiting protrusion ring 301. The bottom of the inner shell 3 is also provided with a nozzle locking part 307.

[0067] like Figure 5As shown, the rotating bracket 5 is cylindrical in shape. Symmetrical inner cylinder limiting grooves 501 are formed on both sides of the circumference of the rotating bracket 5. Each inner cylinder limiting groove 501 consists of an inclined straight groove and a vertical groove. The inclined straight groove slopes downwards at its head and upwards at its tail. The top of the vertical groove is integrated with the tail of the inclined straight groove, and the height of the head of the inclined straight groove is higher than the height of the bottom of the vertical groove. Two rotating bracket limiting protrusions 502 are symmetrically arranged on the circumference of the rotating bracket 5. These two protrusions 502 can be fitted into the two rotating bracket limiting grooves 303, respectively, to restrict the axial movement of the rotating bracket. Two needle buckle limiting wing movable grooves 503 are also symmetrically formed on the circumference of the rotating bracket 5, allowing the needle buckle limiting wing 701 of the needle buckle 7 to pass through without restricting its movement.

[0068] As shown in Figures 7(a), 7(b), and 7(c), the needle tube buckle 7 is annular and can be fitted onto the top of the syringe 9 to fix the syringe. Symmetrical needle tube buckle limiting wings 701 protruding outwards are provided on both sides of the circumference of the needle tube buckle 7. The two needle tube buckle limiting wings 701 pass through the needle tube buckle limiting wing movable groove 503 on the rotating bracket 5 and are inserted one-to-one into the two needle tube buckle limiting grooves 304, restricting the rotational movement of the needle tube buckle. After the needle tube buckle 7 is installed and the syringe 9 is fixed, the top of the syringe 9 can contact the bottom of the inner cylindrical tube 202 of the outer shell 2. The piston end 802 at the bottom of the piston rod 8, fixed inside the inner cylindrical tube 202 of the outer shell, can extend into the syringe 9. After the piston rod 8 moves downwards, it can squeeze the liquid out of the syringe 9.

[0069] As shown in Figures 6(a) and 6(b), the inner tube 4 is integrally connected from the upper part 401, the middle part 402, and the lower part 403. The upper part 401 of the inner tube includes two symmetrically arranged vertical plates. The bottoms of the two vertical plates are connected to form an annular bottom, and each of the two vertical plates has an inner tube limiting protrusion 404 on its outer surface. The two inner tube limiting protrusions 404 can be inserted into the two inner tube limiting grooves 501 on the rotating bracket 5 in a one-to-one correspondence. The initial position is located at the head end of the inclined straight groove of the inner tube limiting groove 501. The inner diameter of the middle part 402 of the inner tube is smaller than the inner diameter of the upper part 401 of the inner tube, so that a stepped surface 405 is formed at the junction of the upper part 401 and the middle part 402 of the inner tube. The second spring 11 is sleeved on the outside of the syringe 9. The top of the second spring 11 is pressed against the bottom surface of the needle tube buckle 7, and the bottom of the second spring 11 is pressed against the stepped surface 405. When the inner tube is pushed inward along the axial direction, the second spring 11 is compressed. At the same time, the inner tube body limiting protrusion 404 slides upward in a straight line along the inclined straight groove, and the rotating bracket 5 rotates accordingly. When the inner tube body limiting protrusion 404 reaches the end of the inclined straight groove, it stops, and at the same time, the needle of the syringe 9 inserted in the inner tube 4 is exposed. When the inner tube is released, the second spring stretches, pushing the inner tube downwards. Simultaneously, the inner tube's limiting protrusion 404 moves linearly downwards along the vertical groove. It stops when the inner tube's limiting protrusion 404 reaches the bottom of the vertical groove, and the needle of the syringe 9 is re-embedded inside the inner tube 4. Symmetrical inner tube track sliders 406 are provided on both sides of the outer surface of the lower part 403 of the inner tube. The two inner tube track sliders 406 can be fitted one-to-one into the two inner tube track grooves 305 on the inner shell 3, restricting the inner tube 4 to slide only axially up and down.

[0070] As shown in Figures 7(a), 7(b), and 7(c), the nozzle 6 is detachably snapped into the nozzle snap-fit ​​part 307 at the bottom of the inner housing 3, thus sealing the bottom of the inner housing 3.

[0071] Preferably, the automatic injection device for pre-filled syringes in this embodiment further includes a cap locking protection mechanism. This mechanism includes two downward-protruding cap limiting posts 105 located at the bottom of the cap housing 101 and two cap limiting post movable grooves 504 located at the top of the rotating bracket 5. When the inner cylinder limiting protrusion 404 is located at the head end of the inclined straight groove of the inner cylinder limiting groove 501, the bottom surface of the cap limiting post 105 at the bottom of the cap housing 101 abuts against the top of the rotating bracket 5 where there are no cap limiting post movable grooves 504, thus restricting the cap 1 from moving downwards. When the inner cylinder limiting protrusion 404 moves to the tail end of the inclined straight groove, the rotating bracket 5 rotates accordingly, and the cap limiting post movable grooves 504 rotate to a position below the two cap limiting posts 105 at the bottom of the cap housing 101, allowing the cap 1 to move downwards without restriction. This cap locking protection mechanism prevents the cap from being pressed under normal placement, ensuring safe operation by personnel. After removing the nozzle, pressing the inner tube, and rotating the support into place, the cap can be pressed normally, and the medication can begin to be injected.

[0072] Preferably, the automatic injection device for pre-filled syringes in this embodiment further includes an inner tube locking protection mechanism. This mechanism comprises slider protrusions 407 on the two inner tube track sliders 406 and slider protrusion slots 306 on the two inner tube track grooves 305. When the inner tube limiting protrusion 404 moves downward to the bottom of the vertical groove, the two slider protrusions 407 engage with the two slider protrusion slots 306, preventing the inner tube 4 from sliding upward again. This ensures that the inner tube cannot retract after injection, preventing the automatic injector from being reused, and that the needle is covered internally, protecting personnel from injury during item recovery.

[0073] When using this device, select a pre-filled syringe of appropriate size, pre-fill the required medication, and simply attach an automatic injection device to the outside of the pre-filled syringe. When the user needs to inject the medication, simply remove the cap, hold the inner tube perpendicular to the skin at the injection site, and press the inner tube against the skin. The inner tube retracts, exposing the syringe needle. The inner tube then rotates the rotating support until it reaches the limit position, at which point the needle inserts into the skin. Pressing the cap releases the first spring, which in turn pushes the piston rod, slowly and evenly completing the automatic injection. Afterward, remove the needle and release the inner tube. The inner tube automatically extends, completely covering the needle to protect the user from injury. At this point, the inner tube is jammed and cannot retract, rendering the automatic injection device unusable.

[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An automatic injection device suitable for pre-filled syringes, characterized in that: It includes a cap (1), an outer shell (2), an inner shell (3), an inner tube (4), a rotating bracket (5), a nozzle (6), a needle tube buckle (7), a piston rod (8), a syringe (9), a first spring (10), and a second spring (11); The cap (1) includes a cap shell (101), the top of the cap shell (101) is sealed with a bottom opening, and the cap shell (101) has two symmetrical sides on the circumferential surface with cap limiting planes (102) processed from top to bottom. The bottom end of the cap limiting plane (102) is processed into a cap limiting hook (103), and the hook body of the cap limiting hook (103) protrudes outward and the upper surface is the hook surface. The inner center of the top surface of the cap housing (101) is provided with an unlocking cylinder (104) for moving downward to open the piston claw, and the top end of the first spring (10) is located inside the unlocking cylinder (104). The outer shell (2) includes an outer cylindrical shell (201) and an inner cylindrical shell (202), which are fixedly connected by a support bridge (203). The outer cylindrical shell (201) and the inner cylindrical shell (202) are machined from top to bottom on two symmetrical sides of the upper half of the outer cylindrical shell (201). The cap (1) is inserted into the outer cylindrical shell (201). At the same time, the cap limiting plane (102) and the outer shell limiting plane (205) match and fit together to restrict the rotation of the cap. At the same time, the cap limiting hook (103) is provided with an outer shell limiting hook (206) at the corresponding outer shell limiting plane (205). The hook body of the outer shell limiting hook (206) protrudes inward and the lower surface is the hook surface, so that after the cap limiting hook (103) and the outer shell limiting hook (206) are engaged, the cap is restricted from moving upward. The top of the inner cylindrical tube (202) of the outer shell is provided with a piston claw (204). The piston claw (204) can lock the top of the piston rod (801) of the piston rod (8) and the piston claw (204) can press against the bottom end of the first spring (10). When the cap (1) is inserted into the inner cylindrical tube (201) of the outer shell, the cap is forced to move downward. The unlocking cylinder (104) can open the piston claw (204) to release the bottom end of the first spring (10) and the top of the piston rod (801), so that the bottom end of the first spring (10) is sleeved on the top of the piston rod (801) and pushes the piston rod (8) downward. The bottom of the outer shell (2) is also provided with an inner shell positioning corner groove (207); The inner shell (3) is cylindrical in shape. A limiting protrusion (301) is provided on the outer surface of the middle part of the inner shell (3) along the circumferential direction. An inner shell positioning corner protrusion (302) is also provided above the limiting protrusion (301). The part of the inner shell (3) above the limiting protrusion (301) can be fitted and fixed in the outer shell (2) from bottom to top. The inner shell positioning corner protrusion (302) and the inner shell positioning corner groove (207) can match and position fit together. The inner shell (3) has a rotating bracket limiting groove (303) and a needle buckle limiting groove (304) machined on the cylindrical part above the limiting protrusion ring (301); the rotating bracket limiting groove (303) is a slightly curved groove opened along the circumferential direction, and there are two symmetrical grooves on the circumferential surface; the needle buckle limiting groove (304) is an axial groove opened from the top downward, and there are two symmetrical grooves on the circumferential surface. The inner shell (3) has symmetrical inner tube track grooves (305) arranged from top to bottom on both sides of the cylindrical part below the limiting protrusion ring (301); The bottom of the inner shell (3) is also provided with a nozzle snap-fit ​​part (307); The rotating bracket (5) is cylindrical in shape. The inner cylinder limiting groove (501) is symmetrically provided on both sides of the circumference of the rotating bracket (5). The inner cylinder limiting groove (501) is composed of an inclined straight groove and a vertical groove. The inclined straight groove is inclined with the head end pointing downward and the tail end pointing upward. The top end of the vertical groove is connected to the tail end of the inclined straight groove as a whole, and the height of the head end of the inclined straight groove is higher than the height of the bottom end of the vertical groove. Two rotating bracket limiting protrusions (502) are symmetrically arranged on the circumferential surface of the rotating bracket (5). The two rotating bracket limiting protrusions (502) can be embedded in the two rotating bracket limiting grooves (303) one to one to restrict the axial movement of the rotating bracket. Two needle buckle limiting wing movable grooves (503) are symmetrically opened on the circumferential surface of the rotating bracket (5) for the needle buckle limiting wing (701) of the needle buckle (7) to pass through without restricting the movement of the needle buckle limiting wing (701). The needle buckle (7) is ring-shaped and can be fitted onto the top of the syringe (9) to fix the syringe. The two sides of the circumference of the needle buckle (7) are provided with needle buckle limiting wings (701) protruding outward. The two needle buckle limiting wings (701) pass through the needle buckle limiting wing movable groove (503) on the rotating bracket (5) and are inserted into the two needle buckle limiting grooves (304) respectively to restrict the rotation of the needle buckle. After the needle buckle (7) that fixes the syringe (9) is installed, the top of the syringe (9) can contact the bottom of the inner cylindrical tube (202) of the outer shell (2). The piston end (802) of the piston rod (8) fixed in the inner cylindrical tube (202) of the outer shell can extend into the syringe (9). After the piston rod (8) moves downward, it can squeeze the liquid in the syringe (9) to flow out. The inner tube (4) is integrally connected from the upper part (401), the middle part (402) and the lower part (403) of the inner tube; the upper part (401) of the inner tube includes two symmetrically arranged vertical plates, the bottom of the two vertical plates are connected to form an annular bottom, and each of the two vertical plates has an inner tube limiting protrusion (404) on its outer surface. The two inner tube limiting protrusions (404) can be inserted into the two inner tube limiting grooves (501) on the rotating bracket (5) in a corresponding manner, and the initial position is located at the head end of the inclined straight groove of the inner tube limiting groove (501); The inner diameter of the middle part (402) of the inner tube is smaller than the inner diameter of the upper part (401) of the inner tube, so that a stepped surface (405) is formed at the connection between the upper part (401) and the middle part (402) of the inner tube. The second spring (11) is sleeved on the outside of the syringe (9). The top of the second spring (11) is pressed against the bottom surface of the syringe buckle (7), and the bottom of the second spring (11) is pressed against the stepped surface (405). When the inner tube is pushed inward along the axial direction, the second spring (11) is compressed, and at the same time the inner tube body limiting protrusion (40) is closed. 4) Slide upwards along the inclined straight groove, and the rotating bracket (5) rotates accordingly. When the inner cylinder limiting protrusion (404) reaches the end of the inclined straight groove, it stops, and at the same time, the needle of the syringe (9) inserted in the inner tube (4) is exposed. Release the inner tube, the second spring is stretched, and the inner tube is pushed downwards. At the same time, the inner cylinder limiting protrusion (404) moves downwards along the vertical groove. When the inner cylinder limiting protrusion (404) reaches the bottom of the vertical groove, it stops, and the needle of the syringe (9) is buried in the inner tube (4) again. The lower part (403) of the inner tube is provided with two symmetrical inner tube track sliders (406) on the outer surface. The two inner tube track sliders (406) can be embedded in the two inner tube track grooves (305) on the inner shell (3) in a one-to-one correspondence, restricting the inner tube (4) to slide up and down along the axial direction only. The nozzle (6) is detachably snapped into the nozzle snap-fit ​​part (307) at the bottom of the inner shell (3) to close the bottom of the inner shell (3); It also includes a cap locking protection mechanism, which includes two downward protruding cap limiting posts (105) located at the bottom of the cap housing (101) and two cap limiting post movable grooves (504) opened at the top of the rotating bracket (5); When the inner cylinder limiting protrusion (404) is located at the head end of the inclined straight groove of the inner cylinder limiting groove (501), the bottom surface of the cap limiting post (105) at the bottom of the cap housing (101) presses against the top of the rotating bracket (5) where there is no cap limiting post movable groove (504), and the cap (1) is restricted and cannot move downward; when the inner cylinder limiting protrusion (404) moves to the tail end of the inclined straight groove, the rotating bracket (5) rotates accordingly, and the cap limiting post movable groove (504) rotates one by one to the bottom of the two cap limiting posts (105) at the bottom of the cap housing (101), and the cap (1) is unrestricted and can move downward; It also includes an inner tube locking protection mechanism, wherein the inner tube locking protection mechanism is provided with slider protrusions (407) on two inner tube track sliders (406) and slider protrusion slots (306) on two inner tube track grooves (305); When the inner cylinder limiting protrusion (404) moves downward to the bottom of the vertical groove, the two slider protrusions (407) are engaged in the two slider protrusion slots (306) in a corresponding manner, restricting the inner tube (4) from sliding upward again.

2. An automatic injection device suitable for pre-filled syringes according to claim 1, characterized in that: The unlocking cylinder (104) is provided with a first spring top limiting cylinder (107) and a first spring sleeve (106) inside. The top of the first spring (10) is sleeved on the first spring sleeve (106) and located inside the first spring top limiting cylinder (107).

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