Self-locking device for a pen injector and pen injector

Abstract

The utility model discloses a self -locking device of pen type syringe, including pen body still include needle protection sleeve, and needle is placed in the inside of needle protection sleeve, and needle protection sleeve has the state of being able to slide along the axial of pen body of injection waiting and the locking state of locking along the axial of pen body, and push rod cover, push rod cover sets up on pen body, and the lateral wall of push rod cover sets up one self -locking piece at least, and self -locking piece can move to the position of avoidance to the inside of push rod cover to avoid the needle protection sleeve of being in the state of injection waiting, and self -locking piece can also move to the position of stop to the outside of push rod cover to stop the needle protection sleeve of being in the locking state. Self -locking piece can move to the position of stop through various ways, for example: through setting elastic piece and deforming, through the mode position displacement of sliding or rotating to the position of stop. The utility model discloses a self -locking device and the pen type syringe of being in can be convenient for patient to identify whether syringe is fired over.

Description

Technical Field

[0001] This utility model relates to a pre-filled pen injector, and more particularly to a self-locking device for a pen injector and a pen injector. Background Technology

[0002] A pen injector, also called an injection pen, is a pre-filled or refillable medication injection device that resembles a pen in appearance. It is used for diseases requiring regular self-injection, such as diabetes, growth hormone deficiency, and osteoporosis. Pen injectors are widely used by patients due to their portability and ease of injection.

[0003] Existing pen injectors have the following problems: After injection and when the slide returns to its original position, the pen injector will completely reset. Patients cannot quickly determine whether the pen injector in their hand has been used. This may lead to patients misusing the pen injector, which may not only waste the medication but also expose patients to the risk of infection by other bacteria or viruses, which is detrimental to their health. Summary of the Invention

[0004] Purpose of the utility model: The purpose of this utility model is to provide a self-locking device for a pen-type syringe that allows patients to easily identify whether the syringe has been fired, as well as the pen-type syringe itself.

[0005] Technical solution: Define the end used for injection as the injection end and the end used for holding as the holding end; define the direction closer to the injection end as downward and the direction closer to the holding end as upward.

[0006] The present invention discloses a self-locking device for a pen-type syringe, used to lock the pen-type syringe after injection. The pen-type syringe includes a pen body, one end of which has a needle to form an injection end, comprising: A needle protector is disposed at the injection end, with the needle placed inside the needle protector. The needle protector has a ready-to-inject state, capable of sliding along the axial direction of the pen body, and a locked state, capable of locking along the axial direction of the pen body; and... A push rod sleeve is disposed on the pen body. At least one self-locking member is provided on the side wall of the push rod sleeve. The self-locking member can move inward within the push rod sleeve to a clearance position to avoid the needle protective sleeve in the injection-ready state. The self-locking member can also move outward within the push rod sleeve to a stop position to stop the needle protective sleeve in a locked state. The self-locking member can move to the stop position in various ways, such as by deformation using an elastic element, or by displacement through sliding or rotation.

[0007] Furthermore, a self-locking sleeve is slidably disposed within the cavity of the push rod sleeve, and a self-locking pushing part corresponding to the self-locking member is disposed on the outer wall of the self-locking sleeve. The self-locking pushing part can push the self-locking member retracted into the push rod sleeve to a position protruding from the push rod sleeve.

[0008] Furthermore, it also includes: A sliding sleeve is disposed between the needle protective sleeve and the push rod sleeve, and is sleeved on the outside of the push rod sleeve. When the needle protective sleeve is in the injection-ready state, the sliding sleeve can slide away from the injection end. When the needle protective sleeve is in the locked state, the sliding sleeve and the self-locking member interfere along the central axis.

[0009] Furthermore, when the injection end abuts against the injection site, the needle protective sleeve in the injection state can slide from a first position close to the injection end to a second position away from the injection end; an elastic element is provided on the side of the sliding sleeve away from the needle protective sleeve, and the elastic element can drive the needle protective sleeve in the second position to return to the first position after the injection end leaves the injection position; the sliding sleeve is also provided with an elastic self-locking claw, and after the needle protective sleeve returns to its original position, the elastic self-locking claw interferes with the self-locking element.

[0010] Furthermore, the self-locking component is an elastic deformable arm, the push rod sleeve is provided with a self-locking groove, and the outer wall of the self-locking sleeve is provided with a self-locking protrusion for extending into the self-locking groove. When the self-locking sleeve slides along the axial direction of the pen body, the self-locking protrusion can deform the elastic deformable arm in the avoidance position to the stop position.

[0011] Furthermore, a self-locking guide block is provided at the bottom of the self-locking component.

[0012] A pen-type injector includes a pen body, one end of which has a needle to form an injection end, and also includes a self-locking device as described above for the pen-type injector.

[0013] Furthermore, an injection push rod is slidably disposed within the cavity of the push rod sleeve, and the injection push rod and the push rod sleeve are linked together so that when the injection push rod moves toward the injection end, the self-locking member switches from the avoidance position to the stop position.

[0014] Furthermore, it also includes a top cover, the injection push rod is hollow, the inner wall of the injection push rod is provided with several injection push plates, and an injection spring is provided in the cavity of the injection push rod. One end of the injection spring abuts against the top cover, and the other end of the injection spring abuts against the injection push plate. The injection spring is used to apply a force toward the injection end to the injection push rod during the injection process.

[0015] Furthermore, it also includes a guide post, one end of which is fixedly connected to the top cover, and the injection spring is sleeved on the outside of the guide post.

[0016] Beneficial effects: Compared with the prior art, this utility model has the following significant advantages: 1. After the patient removes the pen cap (not shown in this utility model), it prevents the injection needle of the pre-filled syringe from being directly exposed and accidentally injuring the patient; 2. Before injection, the self-locking part on the plunger sleeve is in the avoidance position, so that the needle protection sleeve is in the injection-ready state that can slide along the axis of the pen body, thereby allowing the needle to be exposed for injection; after the pen syringe has finished injecting, the needle protection sleeve is reset, the self-locking part of the plunger sleeve is in the stop position, the needle protection sleeve cannot slide away from the injection end again, and the injection needle cannot be exposed again, making it convenient for the patient to identify whether the pen syringe in their hand has been used. Attached Figure Description

[0017] Figure 1 This is a perspective view of the present invention.

[0018] Figure 2 This is an exploded view of the present invention.

[0019] Figure 3 This is a cross-sectional view of the present invention.

[0020] Figure 4 This is a perspective view of the present invention from a rear view after the pen body and needle tip protective cover have been removed.

[0021] Figure 5 This is a perspective view of the present invention from another angle after the pen body and needle tip protective cover are hidden.

[0022] Figure 6 This is a top view of the present invention with the pen body and needle tip protective sleeve removed.

[0023] Figure 7 This utility model is used when not injected along... Figure 6 A sectional view along the AA direction.

[0024] Figure 8 This utility model is used when not injected along... Figure 6 A cross-sectional view along the BB direction.

[0025] Figure 9 for Figure 7 Enlarged view at point C.

[0026] Figure 10 When this utility model is first inserted into the skin, along... Figure 6 A sectional view along the AA direction.

[0027] Figure 11 for Figure 10Enlarged view at point D.

[0028] Figure 12 In this utility model, when the injection pusher starts to drive the self-locking sleeve to move downwards, along... Figure 6 A cross-sectional view along the BB direction.

[0029] Figure 13 for Figure 12 Enlarged view at point E.

[0030] Figure 14 For this utility model, immediately after injection, along Figure 6 A sectional view along the AA direction.

[0031] Figure 15 for Figure 14 Enlarged view at point F.

[0032] Figure 16 After the sliding sleeve of this utility model is reset, along Figure 6 A sectional view along the AA direction.

[0033] Figure 17 for Figure 16 Enlarged view at point G.

[0034] Figure 18 This is a perspective view of the top cover in this utility model.

[0035] Figure 19 This is a perspective view of the injection plunger in this utility model.

[0036] Figure 20 This is a cross-sectional view of the injection plunger in this utility model.

[0037] Figure 21 This is a perspective view of the sliding sleeve in this utility model.

[0038] Figure 22 This is a cross-sectional view of the sliding sleeve in this utility model.

[0039] Figure 23 This is a perspective view of the first push rod sleeve in the first embodiment of this utility model.

[0040] Figure 24 This is a cross-sectional view of the first push rod sleeve in the first embodiment of this utility model.

[0041] Figure 25 This is a perspective view of the self-locking sleeve in this utility model.

[0042] Figure 26 This is a cross-sectional view of the self-locking sleeve at one angle in this utility model.

[0043] Figure 27 This is a cross-sectional view of the self-locking sleeve from another angle in this utility model.

[0044] Figure 28 This is a perspective view of the pen body in this utility model.

[0045] Figure 29 This is a perspective view of the needle tip protective sleeve in this utility model.

[0046] Figure 30 This is a cross-sectional view of the second push rod sleeve in the second embodiment of this utility model.

[0047] Wherein: 1. Injection push rod; 101. Push rod locking groove; 102. Injection push plate; 103. Drive groove; 2. Injection spring; 3. Top cover; 301. Guide post; 4. Sliding sleeve; 401. Spring support seat; 402. Elastic self-locking claw; 5. Outer spring; 6. First push rod sleeve; 601. First push sleeve deformable claw; 602. First locking inner protrusion; 603. First self-locking component; 604. First self-locking groove; 605. First self-locking guide block; 606. 607. First self-locking guide groove; 7. Self-locking sleeve; 701. Self-locking push part; 702. Self-locking protrusion; 703. Self-locking guide block; 704. Self-locking inner moving block; 8. Pen body; 9. Needle tip protective sleeve; 10. Second push rod sleeve; 1001. Second push sleeve deformable claw; 1002. Second locking inner protrusion; 1003. Second self-locking component; 1004. Second self-locking groove; 1005. Second self-locking guide block; 1006. Second needle support. Detailed Implementation

[0048] The technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0049] Example 1

[0050] See appendix Figures 1 to 28 This utility model provides a pen-type syringe, including a pen body 8 and a self-locking device. One end of the pen body 8 has a needle to form an injection end, and the end of the pen body 8 away from the injection end is a hand-held end. The self-locking device is disposed on the pen body 8.

[0051] Optionally, the pen body 8 contains an injection plunger 1. The pen-type syringe also includes a top cover 3. The injection plunger 1 is hollow, and its inner wall is provided with several injection push plates 102. An injection spring 2 is disposed within the cavity of the injection plunger 1. One end of the injection spring 2 abuts against the top cover 3, and the other end of the injection spring 2 abuts against the injection push plate 102. The optimal design for the injection push plate 102 is to be located at the end of the injection plunger 1 near the injection end, but the injection push plate 102 can also be located at any position within the cavity of the injection plunger 1, as long as the injection spring 2 can push the injection plunger 1.

[0052] Furthermore, the end of the pen body 8 near the hand-held end is detachably connected to the top cover 3. In this embodiment, the top cover 3 closes the end of the pen body 8 near the hand-held end; in other embodiments, the top cover 3 may not close the end of the pen body 8 near the hand-held end.

[0053] Optionally, the pen injector also includes a guide post 301, one end of which is fixedly connected to the top cover 3, and the injection spring 2 is sleeved on the outside of the guide post 301. The guide post 301 is used to guide the injection spring 2 to deform toward the injection end so as to push the injection plunger 1 to slide toward the injection end of the pen body 8.

[0054] See appendix Figures 1 to 28 The self-locking device is installed on the pen body 8 of the pen syringe to lock the pen syringe after injection, so that users can quickly distinguish whether the pen syringe has been used, thereby correctly disposing of pen syringes with unknown status and reducing drug waste. Please refer to the following for the specific structure of the self-locking device.

[0055] The self-locking device includes a needle protector sleeve 9 and a first push rod sleeve 6. The needle protector sleeve 9 is disposed at the injection end of the pen body 8, with the needle inside the needle protector sleeve 9. The needle protector sleeve 9 has an injection-ready state that can slide along the axial direction of the pen body 8, and a locked state that can be locked along the axial direction of the pen body 8. The first push rod sleeve 6 is disposed on the pen body 8, and at least one first self-locking member 603 is provided on the side wall of the first push rod sleeve 6. The first self-locking member 603 can move inward to a clearance position to avoid the needle protector sleeve 9 in the injection-ready state. The first self-locking member 603 can also move outward to a stop position to lock the needle protector sleeve 9 after stopping it.

[0056] As can be seen from the above structure, 1. After the patient removes the pen cap (not shown in this utility model), the needle protector 9 covers the injection needle of the pre-filled syringe, preventing the injection needle of the pre-filled syringe from being directly exposed and accidentally injuring the patient; 2. Before the pen syringe is injected, the first self-locking member 603 on the first push rod sleeve 6 is in the avoidance position, allowing the needle protector 9 to slide up and down along the central axis of the pen body 8, so that the needle can be exposed and inserted into the skin to complete the injection when needed; after the pen syringe is injected, the needle protector 9 is reset, and after the first self-locking member 603 of the first push rod sleeve 6 reaches the stop position, the needle protector 9 cannot slide away from the injection end again, and the injection needle cannot be exposed again, making it convenient for the patient to identify whether the pen syringe in their hand has been used.

[0057] For example, in this embodiment, two first self-locking members 603 are provided on the first push rod sleeve 6, and the two first self-locking members 603 are evenly arranged around the central axis of the first push rod sleeve 6. This allows the needle protective sleeve 9 to be subjected to uniform force and improves the working stability of the needle protective sleeve 9 in the locked state.

[0058] Optionally, in this embodiment, the first self-locking member 603 is an elastic deformable arm. In other embodiments, the first self-locking member 603 can move to the stop position in a variety of ways, such as by deforming by setting an elastic element, or by sliding or rotating to move to the stop position.

[0059] Optionally, a self-locking sleeve 7 is slidably disposed within the cavity of the first push rod sleeve 6. The outer wall of the self-locking sleeve 7 is provided with a self-locking pushing part 701 corresponding to the first self-locking member 603. The self-locking pushing part 701 can push the first self-locking member 603, which is retracted into the first push rod sleeve 6, to a position protruding from the first push rod sleeve 6. After the self-locking sleeve 7 and the first push rod sleeve 6 slide relative to each other, the self-locking pushing part 701 of the self-locking sleeve 7 pushes the first self-locking member 603 to deform away from the central axis, preventing the needle protector 9 from sliding away from the injection end again.

[0060] Furthermore, a first self-locking groove 604 is provided on the first self-locking member 603, and a self-locking protrusion 702 for extending into the first self-locking groove 604 is provided on the outer wall of the self-locking sleeve 7. When the self-locking sleeve 7 slides along the axial direction of the pen body 8, the self-locking protrusion 702 can deform the first self-locking member 603, which is in the avoidance position, to the stop position.

[0061] Furthermore, a first self-locking guide block 605 is provided at the bottom of the first self-locking member 603. The first self-locking guide block 605 is used to guide the self-locking pusher 701 along the axial sliding direction and assist the self-locking pusher 701 in pushing the first self-locking member 603.

[0062] Optionally, the first push rod sleeve 6 has a first self-locking guide groove 607, and the outer wall of the self-locking sleeve 7 is provided with a self-locking guide block 703. The self-locking guide block 703 extends into the first self-locking guide groove 607 to assist in guiding the self-locking sleeve 7 when it slides.

[0063] Optionally, a sliding sleeve 4 is also included. The sliding sleeve 4 is disposed between the needle protective sleeve 9 and the first push rod sleeve 6, and is sleeved on the outside of the first push rod sleeve 6. When the needle protective sleeve 9 is in the injection-ready state, the sliding sleeve 4 can slide away from the injection end. When the needle protective sleeve 9 is in the locked state, the sliding sleeve 4 interferes with the first self-locking member 603 along the central axis.

[0064] Optionally, when the injection end abuts against the injection site, the needle protective sleeve 9 in the injection state can slide from a first position close to the injection end to a second position away from the injection end; an elastic element is provided on the side of the sliding sleeve 4 away from the needle protective sleeve 9. In this embodiment, the elastic element is an outer spring 5. Several spring support seats 401 are provided on the outer wall of the sliding sleeve 4. One end of the outer spring 5 near the injection end abuts against the spring support seat 401, and the other end of the outer spring 5 abuts against other components in the injection pen. The outer spring 5 can drive the needle protective sleeve 9 in the second position to return to the first position after the injection end leaves the injection position.

[0065] Furthermore, the sliding sleeve 4 is also provided with an elastic self-locking claw 402. The elastic self-locking claw 402 is used to deform away from the central axis during the sliding sleeve 4 reset process. When the self-locking push part 701 pushes the first self-locking member 603 away from the central axis until the self-locking position, the first self-locking member 603 abuts against the inner wall of the sliding sleeve 4. During the sliding reset process of the sliding sleeve 4 towards the injection end, since the elastic self-locking claw 402 is elastic, the elastic self-locking claw 402 is also pushed and deformed away from the central axis, so as not to hinder the reset of the sliding sleeve 4. After the sliding sleeve 4 resets, the elastic self-locking claw 402 also resets to the initial state. At this time, along the central axis direction, the elastic self-locking claw 402 interferes with the first self-locking member 603 in the stop position, thereby realizing the interference self-locking of the first self-locking member 603 and the sliding sleeve 4, preventing the sliding sleeve 4 from sliding away from the injection end again.

[0066] Optionally, the injection plunger 1 is slidably disposed within the cavity of the first plunger sleeve 6. A plurality of self-locking inner moving blocks 704 are provided at the bottom of the self-locking sleeve 7, and a plurality of driving grooves 103 are provided on the injection plunger 1, with the self-locking inner moving blocks 704 extending into the driving grooves 103. Thus, when the injection plunger 1 injects, it drives the self-locking sleeve 7 to move towards the injection end, thereby pushing out the first self-locking member 603 through the self-locking pusher 701 on the self-locking sleeve 7. This causes the first self-locking member 603 to abut against the inner wall of the sliding sleeve 4, preventing the sliding sleeve 4 and the needle protective sleeve 9 from sliding away from the injection end again after the sliding sleeve 4 has moved towards the injection end and passed the first self-locking member 603. The movement of the self-locking sleeve 7 can be achieved without the need for an additional power component.

[0067] In addition, the first push rod sleeve 6 is also provided with a number of first push rod deformation claws 601. The number of first push rod deformation claws 601 are evenly arranged around the central axis. The first push rod deformation claws 601 elastically deform away from the central axis in their natural state. The inner side of each first push rod deformation claw 601 is provided with a number of first locking inner protrusions 602 for locking the injection push rod 1. The injection push rod 1 is provided with a number of push rod locking grooves 101 for cooperating with the first locking inner protrusions 602 to lock the injection push rod 1.

[0068] Before injection begins, the sliding sleeve 4 presses against the first push sleeve deformable claw 601, causing the first locking inner protrusion 602 to extend into the push rod locking groove 101 to lock the injection push rod 1. At this time, the injection spring 2 is in a compressed and energy-storing state, which can prevent the pen syringe from being accidentally activated. After injection begins, the sliding sleeve 4 slides towards the hand end under the push of the needle protective sleeve 9. The sliding sleeve 4 releases the pressure on the first push sleeve deformable claw 601, allowing the injection push rod 1 to move towards the injection end under the action of the injection spring 2 and pass over the first locking inner protrusion 602. That is, the injection spring 2 drives the injection push rod 1 to move, realizing drug injection and finally locking the needle protective sleeve 9.

[0069] It is worth noting that the first push rod sleeve 6 is provided with a first needle support seat 606 at one end near the injection end for supporting the pre-filled needle tube (not shown) to abut. The connection between the main body of the first push rod sleeve 6 and the first needle support seat 606 is an elastic element, which allows the present invention to adapt to the support distance requirements between pre-filled needle tubes of different specifications, thereby matching with pre-filled needle tubes of various specifications.

[0070] Example 2

[0071] See appendix Figure 30 And refer to the appendix Figures 1 to 29 The difference between the second embodiment and the first embodiment lies only in the different push rod sleeves. The second push rod sleeve 10 in the second embodiment has the following shape: The second push rod sleeve 10 is provided with several second push rod sleeve deformable claws 1001, which are evenly arranged around the central axis of the second push rod sleeve 10. In its natural state, the second push rod sleeve deformable claws 1001 elastically deform away from the central axis. Each second push rod sleeve deformable claw 1001 has several second locking inner protrusions 1002 on its inner side for locking the injection push rod 1. The second push rod sleeve deformable claw 1001 has an inwardly tapered portion extending towards the central axis at the end facing the injection end. The inwardly tapered portion is arc-shaped, and its function is as follows: to minimize interference with the sliding sleeve 4 during the initial assembly of this utility model, facilitating assembly. A second needle tube support seat 1006 is provided at the end of the second push rod sleeve 10 near the injection end for supporting the pre-filled needle tube. The connection between the main body of the second push rod sleeve 10 and the second needle tube support seat 1006 is an elastic element.

[0072] Optionally, the sidewall of the second push rod sleeve 10 is provided with a plurality of second self-locking members 1003 for deforming away from the central axis, and the second self-locking members 1003 are evenly distributed around the central axis; the end of the second push rod sleeve 10 near the injection end is provided with a second needle support seat 1006 for supporting the pre-filled needle tube (not shown) to abut, and the connection between the main body of the second push rod sleeve 10 and the second needle support seat 1006 is an elastic member; a second self-locking groove 1004 is provided on the second push rod sleeve 10 below the second self-locking member 1003 (defined as the direction towards the injection end as downward), and the second push rod sleeve 10 is provided with a second self-locking guide groove for guiding the self-locking sleeve 7; a second self-locking guide block 1005 is provided at the bottom of the second self-locking member 1003 for guiding the self-locking push part 701, and the guide surface of the second self-locking guide block 1005 for guiding is arc-shaped.

Claims

1. A self-locking device for a pen-type syringe, used to lock the pen-type syringe after injection, the pen-type syringe comprising a pen body, one end of the pen body having a needle to form an injection end, characterized in that: include: Needle protector (9), the needle protector (9) is disposed at the injection end, the needle is placed inside the needle protector (9), the needle protector (9) has an injection state in which it can slide along the axis of the pen body, and a locking state in which it is locked along the axis of the pen body. as well as, A push rod sleeve is disposed on the pen body. At least one self-locking member is provided on the side wall of the push rod sleeve. The self-locking member can move inward to the avoidance position to avoid the needle protection sleeve (9) in the injection state. The self-locking member can also move outward to the stop position to lock the needle protection sleeve (9) after stopping it.

2. The self-locking device for a pen-type syringe according to claim 1, characterized in that: A self-locking sleeve (7) is slidably disposed in the cavity of the push rod sleeve. The outer wall of the self-locking sleeve (7) is provided with a self-locking push part (701) corresponding to the self-locking member. The self-locking push part (701) can push the self-locking member that is retracted into the push rod sleeve to a position that protrudes from the push rod sleeve.

3. The self-locking device for a pen-type syringe according to claim 1, characterized in that: Also includes: The sliding sleeve (4) is disposed between the needle protective sleeve (9) and the push rod sleeve, and is sleeved on the outside of the push rod sleeve. When the needle protective sleeve (9) is in the injection-ready state, the sliding sleeve (4) can slide away from the injection end. When the needle protective sleeve (9) is in the locked state, the sliding sleeve (4) interferes with the self-locking component.

4. The self-locking device for a pen-type syringe according to claim 3, characterized in that: When the injection end abuts against the injection site, the needle protective sleeve (9) in the injection state can slide from a first position close to the injection end to a second position away from the injection end; the sliding sleeve (4) is provided with an elastic element on the side away from the needle protective sleeve (9), and the elastic element can drive the needle protective sleeve (9) in the second position to return to the first position after the injection end leaves the injection position. The sliding sleeve (4) is also provided with an elastic self-locking claw (402), and after the needle protective sleeve (9) is reset, the elastic self-locking claw (402) interferes with the self-locking element.

5. The self-locking device for a pen-type syringe according to claim 2, characterized in that: The self-locking component is an elastic deformable arm. The outer wall of the self-locking sleeve (7) is provided with a self-locking protrusion (702). When the self-locking sleeve (7) slides along the axial direction of the pen body, the self-locking protrusion (702) can deform the elastic deformable arm in the avoidance position to the stop position.

6. The self-locking device for a pen-type syringe according to claim 2, characterized in that: A self-locking guide block is provided at the bottom of the self-locking component.

7. A pen-type syringe, comprising a pen body having a needle to form an injection end, characterized in that: It also includes a self-locking device for the pen injector as described in any one of claims 1-6.

8. A pen-type syringe according to claim 7, characterized in that: The injection push rod (1) is slidably disposed in the cavity of the push rod sleeve. The injection push rod (1) and the push rod sleeve are linked together so that when the injection push rod (1) moves toward the injection end, the self-locking member switches from the avoidance position to the stop position.

9. A pen-type syringe according to claim 8, characterized in that: It also includes a top cover (3), the injection push rod (1) is hollow, the inner wall of the injection push rod (1) is provided with a plurality of injection push plates (102), the cavity of the injection push rod (1) is provided with an injection spring (2), one end of the injection spring (2) abuts against the top cover (3), the other end of the injection spring (2) abuts against the injection push plate (102), and the injection spring (2) is used to apply a force toward the injection end to the injection push rod (1) during the injection process.

10. A pen-type syringe according to claim 9, characterized in that: It also includes a guide post (301), one end of which is fixedly connected to the top cover (3), and the injection spring (2) is sleeved on the outside of the guide post (301).

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