Safe injection device

Abstract

The utility model provides a safety injection device which comprises an injector and a safety device. The safety device comprises a protective outer sleeve, a mounting inner sleeve and an elastic piece; the mounting inner sleeve is used for accommodating and fixing an injector, and the mounting inner sleeve is arranged in the protective outer sleeve in a sliding manner; a first locking mechanism for locking the mounting inner sleeve at the injection position and a second locking mechanism for locking the mounting inner sleeve at the protection position are arranged between the mounting inner sleeve and the protection outer sleeve; an unlocking excitation piece for unlocking the first locking mechanism is arranged on a piston rod of the injector; the elastic piece applies reset force for moving from the injection position to the protection position to the mounting inner sleeve; a plurality of first guide pieces are formed on the periphery of the protective jacket; a guide support is arranged on the piston rod and comprises a second guide part in sliding fit with the first guide part. Bending deformation of the piston rod is limited through the sliding guiding structure composed of the first guiding piece and the second guiding piece, and the problem that the piston rod is broken due to improper force application is effectively solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of medical equipment, and in particular relates to a safe injection device. Background Art

[0002] In the medical field, syringes are disposable items to avoid cross infection. To prevent the needle from accidentally injuring the user or the syringe from being reused after use, a special safety device is usually installed on the syringe to automatically activate the safety device to cover and protect the needle after the injection is completed. On the one hand, it can prevent accidental injury by the needle, and on the other hand, it can also prevent the syringe from being reused, thereby improving the safety of the syringe.

[0003] However, currently there is a kind of slender prefilled syringe. Since its piston rod is relatively slender and the liquid medicine in the syringe is relatively viscous, it is difficult to push the piston rod and a greater force is required for pushing. If the force is applied in an improper direction during the pushing process, the piston rod may bend and break, affecting the injection efficiency. Utility Model Content

[0004] In view of the above shortcomings of the prior art, the purpose of the utility model is to provide a safe injection device which is easy to use and has a piston rod that is not easy to break. The device can cover and protect the needle of the syringe after the injection is completed to avoid accidental needle injury and the syringe being reused.

[0005] In order to achieve the above-mentioned object and other related objects, the utility model provides a safety injection device, comprising a syringe and a safety device; the safety device comprises a protective outer sleeve, a mounting inner sleeve and an elastic member; the mounting inner sleeve is used to accommodate and fix the syringe, and the mounting inner sleeve is slidably arranged in the protective outer sleeve along its axial direction; a first locking mechanism for locking the mounting inner sleeve in an injection position and a second locking mechanism for locking the mounting inner sleeve in a protection position are arranged between the mounting inner sleeve and the protective outer sleeve; the syringe comprises a syringe barrel, a needle assembly, a piston and a piston rod; the piston seals and slides in the syringe barrel, and the lower end of the piston rod extends into the syringe barrel It is fixedly connected to the piston; an unlocking trigger piece for unlocking the first locking mechanism is provided on the piston rod; when the first locking mechanism is unlocked, the elastic piece applies a reset force to the installation inner sleeve to move from the injection position to the protection position; a plurality of first guide pieces are formed on the outer periphery of the protective outer sleeve; a guide bracket is provided on the piston rod, and the guide bracket includes a second guide piece that slides with the first guide piece in the axial direction of the piston rod; the utility model utilizes the guide structure formed by the first guide piece and the second guide piece to limit the bending deformation of the piston rod, effectively improves the stability of the piston rod during the injection process, and avoids the problem of the piston rod breaking due to improper force application.

[0006] Preferably, the guide bracket includes a booster head coaxially mounted on the piston rod, and the second guide member is provided with the booster head; the utility model utilizes the booster head to increase the contact area with the operator's hand, thereby reducing the difficulty of pushing the piston rod.

[0007] Preferably, the protective outer sleeve comprises an outer sleeve body and an elastic member mounting seat located at the upper end of the outer sleeve body; the elastic member mounting seat is used to mount the elastic member; the mounting inner sleeve comprises an inner sleeve body and a syringe fixing seat located at the upper end of the inner sleeve body, and the syringe fixing seat is used to fix the outer flange of the syringe barrel; the inner sleeve body of the mounting inner sleeve is located in the elastic member, and the two ends of the elastic member are respectively abutted against the bottom surface of the elastic member mounting seat and the bottom surface of the syringe fixing seat; since the mounting inner sleeve is relatively fixed to the syringe barrel of the syringe, when the injection of the syringe is completed, the mounting inner sleeve will move from the injection position to the protection position under the action of the elastic member, so that the needle of the syringe is retracted from the outside of the protective outer sleeve into the protective outer sleeve, and is shielded and protected by the protective outer sleeve, which not only avoids the needle of the syringe from stabbing people, but also effectively prevents the used syringe from being reused to cause cross infection.

[0008] Preferably, an inner limiter is formed on the bottom surface of the elastic member mounting seat to prevent the elastic member from entering the outer sleeve body, so as to ensure the accuracy of the installation position of the elastic member.

[0009] Preferably, the first locking mechanism includes a first locking claw located on the syringe fixing seat and a second locking claw located on the elastic member mounting seat; the first locking claw cooperates with the second locking claw to limit the upward movement of the mounting inner sleeve to stabilize the mounting inner sleeve at the injection position, ensuring that the syringe can successfully complete the push injection work.

[0010] Preferably, an unlocking block is provided on the second locking claw; when the unlocking trigger member squeezes the unlocking block, the second locking claw rotates in a direction away from the piston rod axis to disengage from the first locking claw; at this time, the external force on the piston rod is cancelled, and the inner sleeve can be installed to move upward to a protective position under the resetting action of the elastic member to allow the needle assembly of the syringe to retract into the protective outer sleeve.

[0011] Preferably, the second locking mechanism includes a stop-retraction protrusion located on the outer wall of the lower end of the inner sleeve body and a stop-retraction opening located on the outer wall of the outer sleeve body; the stop-retraction protrusion and the stop-retraction opening cooperate to lock the installed inner sleeve in the protection position, which can not only prevent the installed inner sleeve from being separated from the protective outer sleeve, but also prevent the installed inner sleeve from moving back to the injection position to cause the needle assembly of the syringe to leak out.

[0012] Preferably, a guide groove extending along the axial direction of the piston rod is provided on the outer wall of the inner sleeve body, and a guide claw slidingly matched with the guide groove is provided on the outer sleeve body; a gap forming a stop opening is provided between the guide claw and the elastic member mounting seat; the cooperation between the guide claw and the guide groove can effectively ensure the movement stability of the installed inner sleeve.

[0013] Preferably, a guide block is provided on the guide claw; when the anti-retraction protrusion squeezes the guide block of the guide claw, the guide claw rotates in a direction away from the piston rod axis to ensure that the anti-retraction protrusion can smoothly pass over the guide claw and enter the anti-retraction mouth.

[0014] Preferably, a handle is formed on the elastic member mounting seat to support the index finger and middle finger of the operator during the injection process.

[0015] As described above, a safety injection device of the utility model has the following beneficial effects:

[0016] 1) The safety injection device of the utility model has two states, namely, an injection state and a protection state; in the injection state, the first locking claw of the installation inner sleeve cooperates and locks with the second locking claw of the protective outer sleeve, so that the installation inner sleeve is in the injection position; at this time, the elastic member is compressed to store energy, and the needle assembly of the syringe extends out of the protective outer sleeve; when injection is required, it is only necessary to pull out the needle sleeve of the syringe, so that the needle of the syringe is exposed and inserted into the corresponding position, and then press the piston rod of the syringe to perform the push injection work; in the later stage of push injection, the unlocking release member on the piston rod contacts the unlocking inclined surface on the second locking claw, so that the second locking claw swings in a direction away from the axial direction of the piston rod to disengage from the first locking claw; after completing the push injection work, the operator releases the piston rod, and the installation inner sleeve will move up relative to the protective outer sleeve under the action of the elastic member until the stop protrusion of the installation inner sleeve is stuck in the stop mouth of the protective outer sleeve; at this time, the installation inner sleeve is in the protection position, and the needle of the syringe is retracted into the protective outer sleeve, and is shielded and protected by the protective outer sleeve, which not only avoids the problem of accidental injury by the needle, but also avoids the secondary use of the syringe.

[0017] 2) The guide structure formed by the first guide piece formed on the outer periphery of the protective sleeve and the second guide piece on the piston rod can not only effectively ensure the axial stability of the piston rod during the injection process, but also limit the bending deformation of the piston rod, thereby avoiding the breakage of the piston rod due to improper force during the injection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A perspective view of a safety injection device.

[0019] Figure 2 A vertical cross-sectional view of the syringe.

[0020] Figure 3An exploded view of the installation.

[0021] Figure 4 Schematic diagram of the unlocking trigger installed on the guide bracket.

[0022] Figure 5 It is a vertical cross-sectional view of the safety injection device before injection.

[0023] Figure 6 Isometric cross-section view of the safety injection device at the end of injection.

[0024] Figure 7 It is a vertical cross-sectional view of the safety injection device in the protection state.

[0025] Figure 8 Schematic diagram of the coordination between the protective outer sleeve and the inner sleeve for installation.

[0026] Fig. 9 A top view of the protective jacket.

[0027] Fig.10 Isometric cutaway view of a protective jacket.

[0028] Fig.11 Isometric section view of the inner sleeve being installed.

[0029] Description of Reference Numerals

[0030] Syringe 1, syringe 11, outer flange 111, needle assembly 12, needle 121, needle cover 122, piston 13, piston rod 14, safety device 2, protective jacket 21, jacket body 211, elastic member mounting seat 212, inner limit member 2121, claw support member 213, vertical slide groove 214, handle 215, inner sleeve 22 installation, inner sleeve body 221, guide slide groove 2211, syringe fixing seat 222, flange fixing block 2221, elastic member 23, protective sleeve 24, first locking claw 31, second locking claw 32, unlocking block 321, stop protrusion 41, stop mouth 42, guide claw 43, guide block 431, unlocking trigger member 5, guide bracket 6, booster head 61, vertical slide rod 62. DETAILED DESCRIPTION

[0031] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0032] See also Figures 1 to 11It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the utility model without affecting the effects and purposes that can be achieved by the utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the utility model without substantially changing the technical content.

[0033] like Figure 1 and Figure 5 As shown, the safety injection device involved in the utility model comprises a syringe 1 and a safety device 2. When the syringe 1 completes the injection, the safety device 2 will be automatically activated to cover and protect the needle of the syringe 1 to prevent the needle of the syringe 1 from stabbing a person or the syringe 1 from being reused. For the convenience of description, in the following embodiments, the axial direction of the syringe 1 in the vertical state is defined as the up and down direction.

[0034] Specifically, the structure of the syringe 1 is as follows Figure 2 As shown, it includes a syringe 11, a needle assembly 12, a piston 13 and a piston rod 14; the upper end of the syringe 11 is an open end, and an outer flange 111 is formed at the open end; the lower end of the syringe 11 is a liquid medicine inlet and outlet end, and the liquid medicine inlet and outlet end is used to install the needle assembly 12; the needle assembly 12 includes a needle 121 and a needle cover 122, and the needle cover 122 is used to cover the needle 121 to protect the needle 121; the piston 13 axially slides in the syringe 11 in a sealed manner, and the lower end of the piston rod 14 extends into the syringe 11 and is fixedly connected to the piston 13, so that the liquid medicine can be sucked into or discharged from the syringe 11 by only pushing and pulling the piston rod 14.

[0035] The structure of the safety device 2 is as follows: Figure 3 , Figure 5 and Figure 7As shown, it comprises a protective outer sleeve 21, an installation inner sleeve 22 and an elastic member 23, wherein the elastic member 23 is preferably a spring; the installation inner sleeve 22 is used to accommodate and fix the syringe barrel 11 of the syringe 1, and the installation inner sleeve 22 is slidably arranged in the protective outer sleeve 21 along its axial direction; a first locking mechanism for locking the installation inner sleeve 22 in the injection position and a second locking mechanism for locking the installation inner sleeve 22 in the protection position are arranged between the installation inner sleeve 22 and the protective outer sleeve 21; when the first locking mechanism is unlocked, the installation inner sleeve 22 will be reset by the elastic member 23 The injection position automatically moves to the protection position; when the inner sleeve 22 is installed in the injection position, the needle assembly 12 of the syringe 1 thereon is located outside the protective outer sleeve 21, so that the operator can push the liquid medicine; when the inner sleeve 22 is installed in the protection position, the needle assembly 12 of the syringe 1 thereon is retracted into the protective outer sleeve 21 to shield and protect the needle assembly of the syringe 1; in addition, the unlocking action of the first locking mechanism can be triggered by the unlocking trigger member 5 on the piston rod 14, so that the first locking mechanism can automatically complete the unlocking action in the later stage of push injection.

[0036] In order to prevent the piston rod 14 from bending and breaking during the injection process, Figure 4 , Figure 8 , Fig. 9 and Fig.10 As shown, a plurality of first guide members are formed on the outer periphery of the protective sleeve 21; a guide bracket 6 is provided on the piston rod 14, and the guide bracket 6 includes a second guide member that slides with the first guide member in the axial direction of the piston rod; one of the first guide member and the second guide member is a vertical slide groove 214, and the other is a vertical slide rod 62; through the cooperation between the vertical slide groove 214 and the vertical slide rod 62, not only the stability of the piston rod 14 in the pushing process can be guaranteed, but also the breakage problem of the piston rod 14 caused by improper force during the pushing process can be avoided, thereby ensuring the smooth completion of the pushing operation; in this embodiment, the first guide member is preferably a vertical slide groove 214, and the second guide member is a vertical slide rod 62 that slides with the vertical slide groove 214.

[0037] Furthermore, if Figure 4 The guide bracket 6 includes a booster head 61 formed at the top of each vertical slide rod 62; the booster head 61 is detachably arranged on the piston rod 14, and the top surface of the booster head 61 is larger than the cross-sectional area of ​​the piston rod 14, so that the booster head 61 is used to increase the contact area with the operator's hand and reduce the difficulty of pushing the piston rod 14; in addition, the top surface of the booster head 61 is provided with an anti-slip part, which is an anti-slip pad or an anti-slip groove to avoid slipping during the pushing process.

[0038] It is understandable that the unlocking trigger 5 can be directly set on the piston rod 14 or on the guide bracket 6, and there is no limitation on this. In this embodiment, the unlocking trigger 5 is preferably set on the guide bracket 6 and is integrally formed with the guide bracket 6.

[0039] See also Figure 6 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 The protective outer sleeve 21 includes an outer sleeve body 211 and an elastic member mounting seat 212 formed at the upper end of the outer sleeve body 211, and the elastic member mounting seat 212 is used to mount the elastic member 23; the inner sleeve 22 includes an inner sleeve body 221 and a syringe fixing seat 222 formed at the upper end of the inner sleeve body 221, and the syringe fixing seat 222 is used to fix the outer flange 111 of the syringe barrel 11; when the inner sleeve 22 is installed in the protective outer sleeve 21, the two ends of the elastic member 23 are respectively abutted against the bottom surface of the elastic member mounting seat 212 and the bottom surface of the syringe fixing seat 222; in addition, in order to ensure the sliding stability of the inner sleeve 22 in the protective outer sleeve 21, a guide groove 2211 is provided on the outer wall of the inner sleeve body 221, and a guide claw 43 cooperating with the guide groove 2211 is provided on the outer wall of the outer sleeve body 211; in this embodiment, the guide groove 2211 is preferably set to 2, and the two guide grooves 2211 are symmetrically arranged.

[0040] In a preferred embodiment, if Fig.11 As shown, the syringe fixing seat 222 is a groove structure that can accommodate the outer flange 111, and a plurality of flange fixing blocks 2221 are formed on the inner side wall of the syringe fixing seat 222. The flange fixing blocks 2221 cooperate with the groove bottom of the syringe fixing seat 222 to form a flange clamping groove that clamps the outer flange 111; the flange fixing blocks 2221 are provided with guiding inclined surfaces to guide the outer flange 111 to smoothly enter the flange clamping groove; of course, the outer flange 111 can also be directly fixed in the syringe fixing seat 222 by other means such as screws.

[0041] In a preferred embodiment, if Fig.10 As shown, the bottom surface of the elastic member mounting seat 212 is formed with an inner limit member 2121 that contacts the inner ring of the elastic member. The setting of the inner limit member 2121 can prevent the elastic member 23 from mistakenly entering the outer sleeve body 211, thereby ensuring the accuracy of the installation position of the elastic member 23.

[0042] The preferred structure of the first locking mechanism is as follows Figure 6 , Figure 7 , Fig.10 and Fig.11As shown, it includes a first locking claw 31 and a second locking claw 32 located on the elastic member mounting seat 212; the upward movement of the mounting inner sleeve 22 is limited by the cooperation between the first locking claw 31 and the second locking claw 32, thereby ensuring that the mounting inner sleeve 22 can be stably located at the injection position; wherein, the first locking claw 31 is an inner claw, and the second locking claw 32 is an outer claw; the second locking claw 32 is a cantilever structure, which is arranged on the top of the elastic member mounting seat 212 through a claw support 213; in addition, an unlocking block 321 is provided on the second locking claw 32, and an unlocking inclined surface is provided on the unlocking block 321, so that when the unlocking trigger member 5 squeezes the unlocking inclined surface of the unlocking block 321, the second locking claw 32 can rotate in a direction away from the piston rod axis to disengage from the first locking claw 31, thereby completing the unlocking action of the first locking mechanism; in this embodiment, there are two groups of first locking mechanisms, and the two groups of first locking mechanisms are symmetrically arranged.

[0043] The preferred structure of the second locking mechanism is as follows Figure 6 , Figure 7 , Fig.10 and Fig.11 , which includes a stop-retraction protrusion 41 located on the outer wall of the lower end of the inner sleeve body 221 and a stop-retraction opening 42 located on the outer wall of the outer sleeve body 211; when the inner sleeve 21 is installed and moves upward relative to the protective outer sleeve 21 under the resetting action of the elastic member 23, the stop-retraction protrusion 41 can enter the stop-retraction opening 42; in this way, the inner sleeve 22 can be locked in the protection position by utilizing the cooperation between the stop-retraction protrusion 41 and the stop-retraction opening 42, which can not only prevent the inner sleeve 22 from being separated from the protective outer sleeve 21, but also prevent the inner sleeve 21 from moving back to the injection position to expose the needle 121 of the syringe 1.

[0044] In a preferred embodiment, if Fig.10 and Fig.11 As shown, there are two stop protrusions 41, and the setting positions of the two stop protrusions 41 correspond to the setting positions of the two guide grooves 2211 one by one; at this time, in order to avoid interference between the guide claw 43 and the stop protrusion 41, the guide claw 43 needs to be a cantilever structure, and a guide block 431 is provided on the guide claw 43; specifically, a window corresponding to the guide groove 2211 is provided on the outer wall of the jacket body 211, and the guide claw 43 is provided at the bottom of the window, and the guide claw 43 is between the top of the window and the top of the window. There is a gap between the inner sleeve 21 and the protective outer sleeve 21 to form a stop opening 42; in this way, when the inner sleeve 21 is installed and moves upward relative to the protective outer sleeve 21 under the resetting action of the elastic member 23, the stop protrusion 41 on the inner sleeve 21 squeezes the guide block 431 of the guide claw 43, so that the guide claw 43 rotates in the direction away from the piston rod axis; when the stop protrusion 41 passes over the guide claw 43 and enters the stop opening 42, the guide claw 43 is reset to prevent the inner sleeve 21 from moving back to the injection position to expose the needle 121 of the syringe 1.

[0045] Of course, the top of the window can also extend to the elastic member mounting seat 212. At this time, the gap between the guide claw 43 and the elastic member mounting seat 212 is the stop opening 42. In this way, the contact area between the stop protrusion 41 and the top surface of the stop opening 42 can be increased, effectively ensuring the engagement stability of the stop protrusion 41 and the stop opening 42.

[0046] like Figures 8 to 10 As shown, there are two vertical slide grooves 214, and the two vertical slide grooves 214 and the two guide claws 43 are arranged alternately in the circumferential direction; wherein, the top end of the vertical slide groove 214 extends upward and is connected to the two claw supports 213 at the same time, and a handle 215 is formed on the part of the vertical slide groove 214 located on the two claw supports 213 to support the operator's index finger and middle finger during the injection process.

[0047] like Figure 1 and Figure 5 As shown, a protective sleeve 24 is detachably provided at the bottom end of the protective outer cover 21 , and the protective sleeve 24 is used to shield and protect the needle assembly 12 of the syringe 1 .

[0048] like Figure 5 As shown, when the operator needs to inject the drug solution, the pre-filled syringe 1 must be inserted as a whole into the mounting inner sleeve 22 of the safety device 2. During this process, the outer flange 111 on the syringe 1 will squeeze the guiding slope of the flange fixing block 2221, causing the flange fixing block 2221 to deform. When the outer flange 111 passes over the deformed flange fixing block 2221 and enters the flange slot, the flange fixing block 2221 will reset to limit the outer flange 111, thereby fixing the syringe 1 in the mounting sleeve 22 of the safety device 2; then install the guide bracket 6 on the piston rod 14, so that the vertical slide bar 62 of the guide bracket 6 cooperates with the vertical slide groove 214 outside the protective sleeve 21, and completes the preparation work before injection.

[0049] When in use, the protective cover 24 and the needle cover 122 are removed in sequence to expose the needle 121 of the syringe 1; the operator's index finger and middle finger are supported on the handle 215, and the guide bracket 6 is pressed to inject the drug; Figure 6 As shown, when the drug injection reaches the end, the unlocking release member 5 squeezes the unlocking inclined surface of the unlocking block 321, causing the second locking claw 32 to rotate away from the piston rod axis to disengage from the first locking claw 31, completing the unlocking action of the first locking mechanism.

[0050] like Figure 7As shown, after the drug injection is completed, the unlocking release member 5 contacts the first locking claw 31, and the first locking mechanism is in the unlocked state; at this time, the guide bracket 6 is released, and the installation inner sleeve 22 will move upward relative to the protective outer sleeve 21 under the resetting action of the elastic member 23, so that the needle 121 of the syringe 1 is gradually retracted into the protective outer sleeve 1; when the installation inner sleeve 22 moves to the position where the stop protrusion 41 and the stop opening 42 cooperate, the installation inner sleeve 22 moves to the protection position; at this time, the needle 121 of the syringe 1 is completely in the protective outer sleeve 1; the cooperation of the stop protrusion 41 and the stop opening 42 can not only prevent the installation inner sleeve 22 from being separated from the protective outer sleeve 21, but also prevent the installation inner sleeve 21 from moving back to the injection position to expose the needle 121 of the syringe 1 to avoid secondary use.

[0051] In summary, the utility model effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A safety injection device, comprising a syringe (1) and a safety device (2); the safety device (2) comprising a protective outer sleeve (21), a mounting inner sleeve (22) and an elastic member (23); the mounting inner sleeve (22) is used to accommodate and fix the syringe (1), and the mounting inner sleeve (22) is slidably arranged in the protective outer sleeve (21) along its axial direction; a first locking mechanism for locking the mounting inner sleeve (22) in an injection position and a second locking mechanism for locking the mounting inner sleeve (22) in a protection position are provided between the mounting inner sleeve (22) and the protective outer sleeve (21). The locking mechanism is as follows: the syringe (1) comprises a syringe barrel (11), a needle assembly (12), a piston (13) and a piston rod (14); the piston (13) is sealingly slidable in the syringe barrel (11), and the lower end of the piston rod (14) extends into the syringe barrel (11) and is fixedly connected to the piston (13); an unlocking trigger (5) for unlocking the first locking mechanism is provided on the piston rod (14); when the first locking mechanism is unlocked, the elastic member (23) applies a reset force to the mounting inner sleeve (22) to move from the injection position to the protection position; the characteristics are as follows: A plurality of first guide members are formed on the outer periphery of the protective sleeve (21); a guide bracket (6) is provided on the piston rod (14), and the guide bracket (6) includes a second guide member that is slidably matched with the first guide member in the axial direction of the piston rod.

2. A safe injection device according to claim 1, characterized in that: The guide bracket (6) comprises a booster head (61) coaxially mounted on the piston rod (14), and the second guide member is arranged on the booster head (61).

3. A safety injection device according to claim 1 or 2, characterized in that: The protective outer sleeve (21) comprises an outer sleeve body (211) and an elastic member mounting seat (212) located at the upper end of the outer sleeve body (211); the elastic member mounting seat (212) is used to mount the elastic member (23); the mounting inner sleeve (22) comprises an inner sleeve body (221) and a syringe fixing seat (222) located at the upper end of the inner sleeve body (221); the syringe fixing seat (222) is used to fix the outer flange (111) of the injection barrel (11); the inner sleeve body (221) of the mounting inner sleeve (22) is located in the elastic member (23), and the two ends of the elastic member (23) are respectively in contact with the bottom surface of the elastic member mounting seat (212) and the bottom surface of the syringe fixing seat (222).

4. A safety injection device according to claim 3, characterized in that: The bottom surface of the elastic member mounting seat (212) is formed with an inner limiting member (2121) for preventing the elastic member (23) from entering the outer sleeve body (211).

5. A safe injection device according to claim 3, characterized in that: The first locking mechanism comprises a first locking claw (31) located on the syringe fixing seat (222) and a second locking claw (32) located on the elastic member mounting seat (212); the first locking claw (31) cooperates with the second locking claw (32) to limit the upward movement of the mounting inner sleeve (22).

6. A safety injection device according to claim 5, characterized in that: The second locking claw (32) is provided with an unlocking block (321); when the unlocking trigger (5) presses the unlocking block (321), the second locking claw (32) rotates in a direction away from the piston rod axis to disengage from the first locking claw (31).

7. A safety injection device according to claim 5, characterized in that: The second locking mechanism comprises a stop-retraction protrusion (41) located on the outer wall of the lower end of the inner sleeve body (221) and a stop-retraction opening (42) located on the outer wall of the outer sleeve body (211); The stop-retraction protrusion (41) cooperates with the stop-retraction opening (42) to lock the installation inner sleeve (22) at the protection position.

8. A safe injection device according to claim 7, characterized in that: The outer wall of the inner sleeve body (221) is provided with a guide groove (2211) extending in the axial direction of the piston rod, and the outer sleeve body (211) is provided with a guide claw (43) slidably matched with the guide groove (2211); a gap is provided between the guide claw (43) and the elastic member mounting seat (212) to form a stop opening (42).

9. A safety injection device according to claim 8, characterized in that: The guide claw (43) is provided with a guide block (431); when the stop protrusion (41) presses the guide block (431) on the guide claw (43), the guide claw (43) rotates in a direction away from the piston rod axis.

10. A safe injection device according to claim 3, characterized in that: The elastic member mounting seat (212) is provided with a handle (215).

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