An automatic injection pen capable of slowing down injection speed

Abstract

The present invention proposes an automatic injection pen capable of slowing down the injection speed, comprising a shell, which is arranged along a longitudinal axis and has a proximal end and a distal end. The shell is provided with a chamber for accommodating a syringe, the syringe comprising a syringe body and a piston arranged in the syringe body, and an injection mechanism is provided in the distal end accommodating chamber of the shell. The injection mechanism comprises an injection push rod sleeved with the bottom of the syringe body, and a driving mechanism for driving the injection push rod to move axially. The initial position of the injection push rod maintains a preset distance L with the piston. When the trigger mechanism is activated, the driving mechanism applies a driving force to the injection push rod to accelerate it and accumulate kinetic energy. The injection push rod breaks through the static friction resistance of the piston when it contacts it by virtue of this kinetic energy. In the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston to complete the injection.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and more specifically, to an automatic injection pen capable of slowing down the injection speed. Background Art

[0002] Traditional injection devices typically require manual manipulation of the needle insertion angle and depth, resulting in varying drug delivery effectiveness depending on the user's skill level. With the advancement of pharmaceutical technology, more and more chronic conditions are being treated with periodic dosing. Traditional injection methods are cumbersome and complex, and patients often forget the correct steps before each injection, resulting in the drug not being able to achieve its intended effect.

[0003] The emergence of automatic injection devices offers an effective solution to this problem. They demand simple operation, high patient compliance, and multi-dimensional feedback during the injection process, such as auditory, visual, and tactile. This feedback allows patients to control the entire injection process, reducing anxiety and boosting confidence. Furthermore, the device should have consistent needle insertion depth, eliminating the need for patient adjustment, and avoid exposing the needle tip before and after injection, which could cause fear in patients. Manual injections should be unnecessary, and injection time should be reasonable. After the injection is complete, the device should also have features such as anti-accidental touch and / or anti-reuse protection. At the same time, concerns about personal privacy are increasing, leading to higher demands for product miniaturization, portability, and usability. Achieving these functions and performance to meet market demands is currently attracting increasing attention from engineers and technicians.

[0004] Currently, the existing application number 2023109385598 discloses an automatic injection pen, including a prefilled syringe module, a guide groove is provided on the guide sleeve, a wing-shaped structure corresponding to the guide groove is provided on the injection push rod, a spring is provided on the trigger sleeve, and a rib position is provided at the corresponding wing-shaped structure. When the injection pen is in use, the spring is opened and causes the trigger sleeve to move downward. The trigger slope of the rib position pushes the wing-shaped structure so that the wing-shaped structure can slide in the guide groove, and the injection spring pushes the injection push rod to perform injection.

[0005] However, in order to ensure that the disposable automatic injection pen can be triggered normally, the compression spring of the injection pen needs to overcome the starting resistance of the trigger mechanism and the starting resistance of the rubber stopper in the glass tube at the same time. Therefore, the initial force of the compression spring of the injection pen is often too large, resulting in the injection time of this type of injection pen being too short and the injection speed being too fast. Too fast an injection speed will cause greater pain to the user. Summary of the Invention

[0006] In view of this, the present invention provides an automatic injection pen capable of slowing down injection speed, comprising a housing 4 arranged along a longitudinal axis and having a proximal end and a distal end. The housing 4 defines a chamber for accommodating a syringe, the syringe comprising a syringe body 3 and a piston 32 disposed within the syringe body 3. An injection mechanism 5 is disposed within the distal end accommodating chamber of the housing 4. The injection mechanism 5 comprises an injection pushrod 6 sleeved with the bottom of the syringe body 3, and a drive mechanism 7 for driving the injection pushrod 6 axially. The invention is characterized in that: the injection pushrod 6 initially maintains a preset distance L from the piston 32. When the trigger mechanism is activated, the drive mechanism 7 applies a driving force to the injection pushrod 6 to accelerate its movement and accumulate kinetic energy. With this kinetic energy, the injection pushrod 6 overcomes the static friction resistance of the piston 32 upon contact. In subsequent pushing processes, the driving force only needs to be greater than the kinetic friction resistance of the piston 32 to complete the injection, thereby extending the entire injection time.

[0007] An automatic injection pen capable of slowing down injection speed comprises a housing 4 arranged along a longitudinal axis and having a proximal end and a distal end. The housing 4 comprises a chamber for accommodating a syringe, the syringe comprising a syringe body 3 and a piston 32 disposed within the syringe body 3. An injection mechanism 5 is disposed within the distal end accommodating chamber of the housing 4. The injection mechanism 5 comprises an injection push rod 6 sleeved with the bottom of the syringe body 3 and a drive mechanism 7 for driving the injection push rod 6 axially. The invention is characterized in that: the injection push rod 6 initially maintains a preset distance L from the piston 32. When the trigger mechanism is activated, the drive mechanism 7 applies a driving force to the injection push rod 6 to accelerate its movement and accumulate kinetic energy. The injection push rod 6, with this kinetic energy, overcomes the static friction resistance of the piston 32 upon contact. In the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston 32 to complete the injection, thereby extending the entire injection time.

[0008] Furthermore, the automatic injection pen is equipped with a stepped resistance system, which has: a starting resistance threshold F1 for the drive mechanism 7, a starting resistance threshold F2 for the piston 32, and a stable injection resistance threshold F3 for the piston 32, where F1 < F3 < F2. The automatic injection pen is also equipped with a dynamic energy management system, which includes: a pre-stroke acceleration section, an energy release section, and a continuous control section. The pre-stroke acceleration section is when the driving force of all drive mechanisms is greater than F1, and the injection plunger 6 breaks away from the constraints of the drive mechanism 7 and accelerates to accumulate kinetic energy. The energy release section is when the injection plunger 6 and the piston 32 contact, and the kinetic energy causes the system's instantaneous output force to be greater than F2. The continuous control section is when the driving force of all drive mechanisms is maintained in the range of F3 < driving force < F2. If no preset distance is set between the injection plunger 6 and the piston 32, the initial driving force requirement of the drive mechanism 7 in the pre-stroke acceleration section is reduced to greater than the sum of F1 and F2. The driving force of the drive mechanism 7 in the energy release section and the continuous control section is greater than F3, resulting in a shorter injection time.

[0009] In some embodiments, the distance between the injection push rod 6 and the piston 32 is 3-30 mm. A too long distance will increase the length of the injection pen, and due to the too long distance, there will be a sense of impact during injection. A too short distance will shorten the injection time.

[0010] Furthermore, by adjusting the distance between the injection push rod 6 and the piston 32, the driving force of the elastic drive module in the pre-stroke acceleration section is greater than F1, and the driving force generated by the accumulated elastic potential energy in the continuous control section is maintained at F3 < driving force < F2, and the movement speed of the piston 32 moves according to the preset speed.

[0011] Furthermore, the elastic driving module is an injection spring. Since the driving force of the spring is in a linear relationship, the maximum compression force can be reduced. A smaller rate of change is conducive to stable injection and facilitates better control of the driving force of the pre-stroke acceleration section and the driving force of the continuous control section. If the maximum compression force is large at the beginning, it will be difficult to adjust the force value of the injection process to the smallest possible rate of change.

[0012] In some embodiments, the distance between the injection push rod 6 and the piston 32 is adjusted according to the difference between F2 and F3. When the distance between the injection push rod 6 and the piston 32 is reduced, the driving force of the driving mechanism 7 is greater than F2 when the injection push rod 6 contacts the piston 32. At this time, the driving force of the driving mechanism 7 is mainly used to overcome the starting resistance of the piston 32, and the kinetic energy of the injection push rod 6 is auxiliary, thereby achieving a relatively long injection time; when the distance between the injection push rod 6 and the piston 32 is increased, the injection push rod 6 has been accelerated for a period of time before the moment the injection push rod 6 contacts the piston 32, and has obtained relatively large kinetic energy. At this time, the driving force of the driving mechanism 7 is less than F2. At this time, the kinetic energy of the injection push rod 6 is mainly used to overcome the starting resistance of the piston 32, and the driving force of the driving mechanism 7 is auxiliary. The driving force of the driving mechanism 7 is closer to F3, thereby effectively extending the injection time and reducing the pain of injection.

[0013] In some embodiments, the syringe body 3 is sleeved with the needle protection sleeve 2, the front end of the syringe body 3 is equipped with a needle, and the rear end is a mounting seat 31 protruding from the syringe body 3, the mounting seat 31 abuts against the inner wall of the needle protection sleeve 2, the needle protection sleeve 2 can be selectively axially displaced relative to the housing 4 along the longitudinal axis, and the needle protection sleeve 2 is provided with an injection mechanism 5 away from the proximal end.

[0014] In some embodiments, the injection push rod 6 has an axial accommodating channel, and its inner wall forms a continuous guide structure; the elastic driving mold is coaxially nested in the guide structure, and its compression deformation direction coincides with the movement axis of the injection push rod 6; through the constraint cooperation between the guide structure and the inner wall of the push rod, the elastic driving mold is pre-compressed and stores energy during the no-load stroke of the push rod, and the stored energy is converted into a uniform propulsion force along the axis of the push rod.

[0015] In some embodiments, a spring frame 10 is passed through the injection spring, and the spring frame 10 includes a spring guide rod structure 1011 arranged in the middle of the spring frame 10 and elastic arms arranged on both sides of the spring frame 10. A hook 1012 is provided at the top of the elastic arm. The spring guide rod structure 1011 passes through the interior of the injection spring, so that one end of the injection spring abuts against the injection push rod 6 and the other end abuts against the spring frame 10; a guide sleeve 8 is sleeved on the outside of the spring frame 10, and a platform structure 81 is provided on the upper part of the guide sleeve 8. Before the injection pen is used, the platform structure 81 is engaged with the hook 1012. A guide groove 82 is also provided on the guide sleeve 8, and a wing-shaped structure 61 corresponding to the guide groove 82 is provided on the injection push rod 6. The outer cover of the guide sleeve 8 is provided with a contact The trigger sleeve 9 has an upper end that abuts against the needle protection sleeve 2. A spring piece 91 is provided on the trigger sleeve 9 corresponding to the platform structure 81. A first protrusion 92 is provided on the inner wall of the spring piece 91 and abuts against the hook 1012. A rib 93 is provided on the trigger sleeve 9 corresponding to the wing-shaped structure 61. A return spring 11 is provided on the outer sleeve of the trigger sleeve 9. When the injection pen is in use, the needle protection sleeve 2 pushes the trigger sleeve 9 downward. The spring piece 91 opens under the interaction of the first protrusion 92 and the hook 1012, causing the trigger sleeve 9 to move downward. The rib 93 pushes the wing-shaped structure 61 so that the wing-shaped structure 61 can slide in the guide groove 82. The injection spring pushes the injection push rod 6 to perform injection. At the same time, the spring frame 10 moves downward, and the injection is completed.

[0016] Beneficial effects of the present invention: The present invention proposes an automatic injection pen capable of slowing down the injection speed, comprising a shell 4, which is arranged along a longitudinal axis and has a proximal end and a distal end. The shell 4 is provided with a chamber for accommodating a syringe, the syringe comprising a syringe body 3 and a piston 32 arranged in the syringe body 3, and an injection mechanism 5 is provided in the distal end accommodating chamber of the shell 4. The injection mechanism 5 comprises an injection push rod 6 sleeved with the bottom of the syringe body 3, and a driving mechanism 7 for driving the injection push rod 6 to move axially. The initial position of the injection push rod 6 maintains a preset distance L with the piston 32. When the trigger mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to accelerate it and accumulate kinetic energy. The injection push rod 6 breaks through the static friction resistance of the piston 32 when it contacts it by virtue of the kinetic energy. In the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston 32 to complete the injection, thereby extending the entire injection time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an exploded view of the entire injection pen of the present invention.

[0018] Figure 2 This is a cross-sectional view of the entire injection pen of the present invention.

[0019] Figure 3 for Figure 2 A partial enlarged view of B.

[0020] Figure 4 This is a structural diagram of the guide sleeve of the automatic injection pen capable of slowing down the injection speed of the present invention.

[0021] Figure 5 This is a structural diagram of the spring frame of the automatic injection pen capable of slowing down the injection speed of the present invention.

[0022] Figure 6 This is a structural diagram of the trigger sleeve of the automatic injection pen capable of slowing down the injection speed of the present invention.

[0023] Figure 7 This is a cross-sectional view of the trigger sleeve of the automatic injection pen capable of slowing down the injection speed of the present invention.

[0024] Main component marking instructions

[0025] Needle protection sleeve 2; syringe body 3; mounting seat 31; piston 32; housing 4; injection mechanism 5; injection push rod 6; wing-shaped structure 61; drive mechanism 7; guide sleeve 8; platform structure 81; guide groove 82; trigger sleeve 9; spring piece 91; first protrusion 92; rib position 93; spring frame 10; spring guide rod structure 1011; hook 1012; return spring 11.

[0026] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0027] Example 1:

[0028] like Figure 1-3As shown, an automatic injection pen capable of slowing down the injection speed includes a housing 4 arranged along a longitudinal axis and having a proximal end and a distal end. The housing 4 is provided with a chamber for accommodating a syringe, the syringe comprising a syringe body 3 and a piston 32 disposed within the syringe body 3. An injection mechanism 5 is disposed within the distal end accommodating chamber of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved with the bottom of the syringe body 3 and a drive mechanism 7 for driving the injection push rod 6 to move axially. The injection push rod 6 initially maintains a preset distance from the piston 32. L, when the trigger mechanism is activated, the drive mechanism 7 applies a driving force to the injection push rod 6 to accelerate it and accumulate kinetic energy. The injection push rod 6 breaks through the static friction resistance of the piston 32 by virtue of this kinetic energy. In the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston 32 to complete the injection, thereby extending the entire injection time. The automatic injection pen is provided with a stepped resistance system, which has: a driving mechanism 7 startup resistance threshold F1, a piston 32 startup resistance threshold F2, and a piston 32 stable injection resistance threshold F3, where F1 is satisfied. < F3 < F2; the automatic injection pen is also provided with a dynamic energy management system, which includes: a pre-stroke acceleration section, an energy release section, and a continuous control section. The pre-stroke acceleration section is when the driving force of all driving mechanisms is greater than F1, the injection push rod 6 breaks away from the constraint of the driving mechanism 7 and accelerates to accumulate kinetic energy. The energy release section is at the moment when the injection push rod 6 and the piston 32 contact, and the kinetic energy makes the instantaneous output force of the system greater than F2. The continuous control section is when the driving force of all driving mechanisms is maintained in the range of F3 < driving force < F2. If there is no preset distance between the injection push rod 6 and the piston 32, the initial driving force requirement of the driving mechanism 7 in the pre-stroke acceleration section is reduced to greater than the sum of F1 and F2. The driving force of all driving mechanisms 7 in the energy release section and the continuous control section is greater than F3, resulting in a shorter injection time.

[0029] The distance between the injection push rod 6 and the piston 32 is 3-30 mm. A distance that is too long will increase the length of the injection pen, and due to the distance being too long, there will be a sense of impact during injection. A distance that is too short will shorten the injection time. Different distances are set according to different situations. The distance between the injection push rod 6 and the piston 32 is adjusted according to the difference between F2 and F3. When the distance between the injection push rod 6 and the piston 32 is reduced, the driving force of the driving mechanism 7 is greater than F2 when the injection push rod 6 contacts the piston 32. At this time, the driving force of the driving mechanism 7 is mainly used to overcome the starting resistance of the piston 32, and the kinetic energy of the injection push rod 6 is used as an auxiliary, so as to achieve a relatively long injection time. When the distance between the injection push rod 6 and the piston 32 is increased, the injection push rod 6 is adjusted to the distance between the injection push rod 6 and the piston 32. Before the rod 6 contacts the piston 32, the injection push rod 6 has been accelerated for a period of time and has obtained relatively large kinetic energy. At this time, the driving force of the driving mechanism 7 is less than F2. At this time, the kinetic energy of the injection push rod 6 is mainly used to overcome the starting resistance of the piston 32, and the driving force of the driving mechanism 7 is supplementary. The driving force of the driving mechanism 7 is closer to F3, thereby effectively extending the injection time and reducing the pain of injection. The elastic driving module is an injection spring. Since the driving force value of the spring is a linear relationship, the maximum compression force value can be reduced. A smaller change rate is conducive to stable injection and facilitates better control of the driving force of the pre-stroke acceleration section and the driving force of the continuous control section. If the maximum compression force value is large at the beginning, it is difficult to adjust the force value of the injection process to be as small as possible and the change rate is as small as possible.

[0030] like Figure 4-7As shown, the syringe body 3 is sleeved with the needle protection sleeve 2, the front end of the syringe body 3 is equipped with a needle, and the rear end is a mounting seat 31 protruding from the syringe body 3, the mounting seat 31 abuts against the inner wall of the needle protection sleeve 2, and the needle protection sleeve 2 can selectively shift axially along the longitudinal axis relative to the shell 4, and the needle protection sleeve 2 is provided with an injection mechanism 5 away from the proximal end, and the injection push rod 6 has an axial accommodating channel, and its inner wall forms a continuous guide structure; the elastic drive mold is coaxially nested in the guide structure, and its compression deformation direction coincides with the movement axis of the injection push rod 6; the elastic drive mold is pre-compressed and stored in the no-load stroke of the push rod through the constraint cooperation between the guide structure and the inner wall of the push rod, and the stored energy is converted into a uniform propulsion force along the axis of the push rod, and a spring frame 10 is passed through the injection spring, and the spring frame 10 includes a spring frame arranged in the spring The spring guide rod structure 1011 in the middle of the frame 10 and the elastic arms arranged on both sides of the spring frame 10, the top of which is provided with a hook 1012, the spring guide rod structure 1011 passes through the interior of the injection spring, so that one end of the injection spring abuts against the injection push rod 6 and the other end abuts against the spring frame 10; the outside of the spring frame 10 is sleeved with a guide sleeve 8, the upper part of the guide sleeve 8 is provided with a platform structure 81, when the injection pen is used, the platform structure 81 is engaged with the hook 1012, the guide sleeve 8 is further provided with a guide groove 82, the injection push rod 6 is provided with a wing-shaped structure 61 corresponding to the guide groove 82, the guide sleeve 8 is provided with a trigger sleeve 9, the upper end of the trigger sleeve 9 abuts against the needle protection sleeve 2, the trigger sleeve 9 is provided with a spring piece 91 corresponding to the platform structure 81, the inner wall of the spring piece 91 is provided with a first protrusion 92 and abuts against the hook 1012, The trigger sleeve 9 is provided with a rib 93 at a position corresponding to the wing-shaped structure 61. The trigger sleeve 9 is provided with a return spring 11 on its outer sleeve. When the injection pen is in use, the needle protection sleeve 2 pushes the trigger sleeve 9 downward. The spring piece 91 opens under the interaction of the first protrusion 92 and the hook 1012, causing the trigger sleeve 9 to move downward. The rib 93 pushes the wing-shaped structure 61 so that the wing-shaped structure 61 can slide in the guide groove 82. The injection spring pushes the injection push rod 6 to perform injection. At the same time, the spring frame 10 moves downward, and the injection is completed.

[0031] Beneficial effects of the present invention: The present invention proposes an automatic injection pen capable of slowing down the injection speed, comprising a shell 4, wherein the shell 4 is arranged along the longitudinal axis and has a proximal end and a distal end, wherein the shell 4 is provided with a chamber for accommodating a syringe, wherein the syringe comprises a syringe body 3 and a piston 32 arranged in the syringe body 3, and an injection mechanism 5 is provided in the distal end accommodating chamber of the shell 4, wherein the injection mechanism 5 comprises an injection push rod 6 sleeved with the bottom of the syringe body 3, and a driving mechanism 7 for driving the injection push rod 6 to move axially, wherein the initial position of the injection push rod 6 maintains a preset distance L with the piston 32, and when the trigger mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to accelerate it and accumulate kinetic energy, and the injection push rod 6 breaks through the static friction resistance of the piston 32 when it contacts it by virtue of the kinetic energy, and in the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston 32 to complete the injection, thereby extending the entire injection time.

[0032] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An autoinjector pen capable of slowing down injection speed, comprising a housing arranged along a longitudinal axis and having a proximal end and a distal end; a chamber disposed within the housing for accommodating a syringe, the syringe comprising a syringe body and a piston disposed within the syringe body; an injection mechanism disposed within the distal end accommodating chamber of the housing, the injection mechanism comprising an injection plunger sleeved with a bottom portion of the syringe body; and a drive mechanism for axially moving the injection plunger, characterized in that: The injection push rod maintains a preset distance L from the piston at its initial position. When the drive mechanism is started, the drive mechanism applies a driving force to the injection push rod to accelerate it and accumulate kinetic energy. The injection push rod breaks through the static friction resistance of the piston when it contacts it with the kinetic energy. In the subsequent pushing process, the driving force only needs to be greater than the dynamic friction resistance of the piston to complete the injection. Specifically, by adjusting the distance between the injection push rod and the piston, the driving force of the elastic drive module in the pre-stroke acceleration section is greater than F1, and the driving force generated by the accumulated elastic potential energy in the continuous control section is maintained at F3 < driving force < F2, and the movement speed of the piston moves according to the preset speed.

2. The automatic injection pen capable of slowing down injection speed according to claim 1, characterized in that: The automatic injection pen is equipped with a stepped resistance system, which has: a drive mechanism startup resistance threshold F1, a piston startup resistance threshold F2, and a piston stable injection resistance threshold F3, where F1 < F3 < F2; the automatic injection pen is also equipped with a dynamic energy management system, which includes: a pre-stroke acceleration section, an energy release section, and a continuous control section. The pre-stroke acceleration section is when the driving force of all drive mechanisms is greater than F1, the injection push rod breaks away from the drive mechanism constraints and accelerates to accumulate kinetic energy. The energy release section is when the injection push rod and the piston contact, and the kinetic energy causes the system's instantaneous output force to be greater than F2. The continuous control section is when the driving force of all drive mechanisms is maintained in the range of F3 < driving force < F2.

3. The automatic injection pen capable of slowing down injection speed according to claim 1, characterized in that: The distance between the injection push rod and the piston is 3-30 mm.

4. The automatic injection pen capable of slowing down injection speed according to claim 1, characterized in that: The elastic driving module is an injection spring.

5. The automatic injection pen capable of slowing down injection speed according to claim 1, characterized in that: The distance between the injection push rod and the piston is adjusted according to the difference between F2 and F3. When the distance between the injection push rod and the piston is reduced, the driving force of the driving mechanism is greater than F2 when the injection push rod contacts the piston, and the driving force of the driving mechanism is mainly used to overcome the starting resistance of the piston, and the kinetic energy of the injection push rod is auxiliary. When the distance between the injection push rod and the piston is increased, the injection push rod stores energy before the injection push rod contacts the piston, and the driving force of the driving mechanism is less than F2. The kinetic energy of the injection push rod is mainly used to overcome the starting resistance of the piston, and the driving force of the driving mechanism is auxiliary.

6. The automatic injection pen capable of slowing down the injection speed according to claim 5, characterized in that: The injection push rod has an axial accommodating channel, the inner wall of which forms a continuous guide structure; the elastic drive mold is coaxially nested in the guide structure, and its compression deformation direction coincides with the movement axis of the injection push rod; through the constraint cooperation between the guide structure and the inner wall of the push rod, the elastic drive mold is pre-compressed and stores energy during the no-load stroke of the push rod, and the stored energy is converted into a uniform propulsion force along the axis of the push rod.

7. The automatic injection pen capable of slowing down injection speed according to claim 4, characterized in that: The injection spring is provided with a spring frame, which includes a spring guide rod structure arranged in the middle of the spring frame and elastic arms arranged on both sides of the spring frame. A hook is provided at the top of the elastic arm. The spring guide rod structure passes through the injection spring, so that one end of the injection spring abuts against the injection push rod and the other end abuts against the spring frame; a guide sleeve is sleeved on the outside of the spring frame, and a platform structure is provided on the upper part of the guide sleeve. Before the injection pen is used, the platform structure is engaged with the hook, and a guide groove is further provided on the guide sleeve. A wing-shaped structure corresponding to the guide groove is provided on the outer shell of the guide sleeve. A trigger sleeve is provided on the outer shell of the guide sleeve, and the upper end of the trigger sleeve abuts against the needle protection sleeve. A spring piece is provided at the corresponding platform structure of the trigger sleeve. The inner wall of the spring piece is provided with a first protrusion and abuts against the hook. The trigger sleeve is provided with a rib at a position corresponding to the wing-shaped structure, and a return spring is provided on the outer sleeve of the trigger sleeve. When the injection pen is in use, the needle protection sleeve pushes the trigger sleeve downward, and the spring sheet opens under the interaction between the first protrusion and the hook, causing the trigger sleeve to move downward. The rib pushes the wing-shaped structure so that the wing-shaped structure can slide in the guide groove, and the injection spring pushes the injection push rod to perform injection. At the same time, the spring frame moves downward, and the injection is completed.

8. The automatic injection pen capable of slowing down injection speed according to claim 1, characterized in that: The syringe body is sleeved with the needle protection sleeve. A needle is installed at the front end of the syringe body, and the rear end is a mounting seat protruding from the syringe body. The mounting seat abuts against the inner wall of the needle protection sleeve. The needle protection sleeve can be selectively displaced axially relative to the shell along the longitudinal axis. The needle protection sleeve is provided with an injection mechanism away from the proximal end.

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