Automatic injection pen capable of reducing injection speed

Abstract

The invention provides an automatic injection pen capable of slowing down injection speed, which comprises a shell, the shell is arranged along a longitudinal axis and is provided with a near end and a far end, a cavity for accommodating an injector is arranged in the shell, the injector comprises an injector body and a piston arranged in the injector body, and the piston is arranged in the cavity. An injection mechanism is arranged in a far-body-end containing cavity of the shell and comprises an injection push rod arranged at the bottom of the injector body in a sleeving mode and a driving mechanism driving the injection push rod to move axially, and a preset distance L is kept between the initial position of the injection push rod and a piston. The driving mechanism applies driving force to the injection push rod to enable the injection push rod to move in an accelerated mode and accumulate kinetic energy, the injection push rod breaks through static friction resistance when making contact with the piston by means of the kinetic energy, and injection can be completed as long as the driving force is larger than the dynamic friction resistance of the piston in the follow-up pushing process.

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 usually require proficient mastery of the injection angle and depth, and manual injection, resulting in certain differences in the drug injection effect due to the proficiency of the user. With the development of pharmaceutical technology, more and more chronic diseases are treated with cycle administration. The traditional injection method is cumbersome and complex, and patients may forget the usage steps before each injection, resulting in the drug being unable to exert its due effect.

[0003] The emergence of automatic injection devices provides an effective solution to this problem. People hope that the injection device is easy to operate, has high patient compliance, and has multi-dimensional feedback during the injection process, such as auditory, visual, and tactile. Patients can control the entire injection process by obtaining feedback signals, reducing anxiety and enhancing confidence; at the same time, the injection depth is stable and consistent, without the need for patients to adjust, and the needle tip is avoided from being exposed before and after injection to cause fear to patients; the injection process does not require manual injection and the injection time is reasonable; after injection, it should also have functions such as anti-misoperation and / or anti-secondary use. At the same time, people pay more attention to personal privacy issues and put forward higher requirements for the miniaturization, portability, and usability of products. How to achieve the above functions and performance to meet market demand has attracted more and more attention from engineering and technical personnel.

[0004] Currently, the existing application No. 2023109385598 discloses an automatic injection pen, including a pre-filled syringe module. A guide groove is provided at the guide sleeve, and a wing-shaped structure corresponding to the guide groove is provided at the injection push rod. A shrapnel is provided at the trigger sleeve, and a rib position is provided at the corresponding wing-shaped structure. When the injection pen is in use, the shrapnel opens and the trigger sleeve moves downward, and 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 for injection.

[0005] However, for this disposable automatic injection pen, in order to ensure normal triggering, the compression spring of the injection pen needs to overcome the starting resistance of the triggering 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 too short an injection time and too fast an injection speed for such injection pens. An overly fast injection speed will cause more 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 the injection speed, comprising a housing 4, which is arranged along a longitudinal axis and has a proximal end and a distal end. A chamber for accommodating a syringe is provided in the housing 4. The syringe includes a syringe body 3 and a piston 32 disposed in the syringe body 3. An injection mechanism 5 is provided in the accommodation chamber at the distal end of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved on the bottom of the syringe body 3 and a driving mechanism 7 for driving the injection push rod 6 to move axially. It is characterized in that: the injection push rod 6 maintains a preset distance L from the piston 32 at the initial position. When the triggering mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to make it accelerate and accumulate kinetic energy. The injection push rod 6 breaks through its static friction resistance when contacting the piston 32 by virtue of this kinetic energy. During 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, so that the entire injection time is lengthened.

[0007] An automatic injection pen capable of slowing down the injection speed, comprising a housing 4, which is arranged along a longitudinal axis and has a proximal end and a distal end. A chamber for accommodating a syringe is provided in the housing 4. The syringe includes a syringe body 3 and a piston 32 disposed in the syringe body 3. An injection mechanism 5 is provided in the accommodation chamber at the distal end of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved on the bottom of the syringe body 3 and a driving mechanism 7 for driving the injection push rod 6 to move axially. It is characterized in that: the injection push rod 6 maintains a preset distance L from the piston 32 at the initial position. When the triggering mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to make it accelerate and accumulate kinetic energy. The injection push rod 6 breaks through its static friction resistance when contacting the piston 32 by virtue of this kinetic energy. During 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, so that the entire injection time is lengthened.

[0008] Furthermore, the auto-injector pen is provided with a stepped resistance system, and the stepped resistance system has: a driving mechanism 7 start resistance threshold F1, a piston 32 start resistance threshold F2, and a piston 32 smooth injection resistance threshold F3, where F1 < F3 < F2 is satisfied; the auto-injector pen is also provided with a dynamic energy management system, which includes: a pre-travel acceleration section, an energy release section, and a continuous control section. The pre-travel 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 contacts the piston 32, and the kinetic energy makes the system instantaneously output a force greater than F2. The continuous control section is that the driving force of all driving mechanisms is maintained in the range of F3 < driving force < F2. If there is no preset spacing between the injection push rod 6 and the piston 32, the initial driving force requirement of the driving mechanism 7 in the pre-travel acceleration section is reduced to be greater than the sum of F1 and F2, and all driving mechanisms 7 in the energy release section and the continuous control section are greater than F3, resulting in a shorter injection time.

[0009] In some embodiments, the spacing between the injection push rod 6 and the piston 32 is 3 - 30 mm. An overly long spacing will increase the length of the injector pen, and due to the overly long spacing, there will be a sense of impact during injection. An overly short spacing will result in a shorter injection time.

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

[0011] Furthermore, the elastic driving module is an injection spring. Since the driving force value of the spring is a linear relationship, it can reduce the maximum compression force value. A smaller change rate is beneficial for stable injection and is convenient for better controlling the driving force in the pre-travel acceleration section and the driving force in the continuous control section. If the maximum compression force value is very large at the beginning, it will be very difficult to adjust the force value during the injection process to be as small as possible and have as small a change rate as possible.

[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 at the moment when the injection push rod 6 contacts the piston 32 is greater than F2. 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, 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 accelerated for a period of time before contacting the piston 32 and has obtained a 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, effectively extending the injection time and reducing the injection pain.

[0013] In some embodiments, the syringe body 3 is sleeved with the needle protection sleeve 2. A needle is installed at the front end of the syringe body 3, 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 selectively axially displace relative to the housing 4 along the longitudinal axis. An injection mechanism 5 is provided at the end of the needle protection sleeve 2 away from the proximal end.

[0014] In some embodiments, the injection push rod 6 has an axial accommodation channel, and its inner wall forms a continuous guiding structure; the elastic driving die is coaxially nested in the guiding structure, and its compression deformation direction coincides with the movement axis of the injection push rod 6; through the constraint cooperation between the guiding structure and the inner wall of the push rod, the elastic driving die is pre-compressed and energy-stored 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 holder 10 runs through the injection spring. The spring holder 10 includes a spring guide rod structure 1011 disposed in the middle of the spring holder 10 and spring arms disposed on both sides of the spring holder 10. A catch 1012 is provided at the top end of the spring arm. The spring guide rod structure 1011 passes through the inside of the injection spring, such that one end of the injection spring abuts against the injection push rod 6, and the other end abuts against the spring holder 10. A guide sleeve 8 is sleeved outside the spring holder 10. 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 catch 1012. A guide groove 82 is also provided at the guide sleeve 8. A wing-shaped structure 61 corresponding to the guide groove 82 is provided at the injection push rod 6. A trigger sleeve 9 is sleeved outside the guide sleeve 8. The upper end of the trigger sleeve 9 abuts against the needle protection sleeve 2. A spring piece 91 is provided at 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 catch 1012. A rib 93 is provided at the trigger sleeve 9 corresponding to the wing-shaped structure 61. A return spring 11 is sleeved outside the trigger sleeve 9. During the use of the injection pen, when 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 catch 1012, causing the trigger sleeve 9 to move downward. The rib 93 pushes the wing-shaped structure 61, enabling the wing-shaped structure 61 to slide in the guide groove 82. The injection spring pushes the injection push rod 6 for injection. At the same time, the spring holder 10 moves downward, and the injection ends.

[0016] Advantages of the present invention: The present invention provides an automatic injection pen capable of slowing down the injection speed, including a housing 4. The housing 4 is arranged along a longitudinal axis and has a proximal end and a distal end. A chamber for accommodating a syringe is provided inside the housing 4. The syringe includes a syringe body 3 and a piston 32 disposed inside the syringe body 3. An injection mechanism 5 is provided in the chamber at the distal end of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved at the bottom of the syringe body 3, and a driving mechanism 7 for driving the axial movement of the injection push rod 6. The injection push rod 6 is initially positioned at a preset distance L from the piston 32. After the trigger mechanism is activated, the driving 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 relies on this kinetic energy to break through the static friction resistance when contacting the piston 32. During 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 lengthening the entire injection time. Description of the Drawings

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

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

[0019] Figure 3 is Figure 2 the partial enlarged view B of

[0020] Figure 4 The structural diagram of the guide sleeve of the automatic injection pen capable of slowing down the injection speed according to the present invention.

[0021] Figure 5 The structural diagram of the spring holder of the automatic injection pen capable of slowing down the injection speed according to the present invention.

[0022] Figure 6 The structural diagram of the trigger sleeve of the automatic injection pen capable of slowing down the injection speed according to the present invention.

[0023] Figure 7 The sectional view of the trigger sleeve of the automatic injection pen capable of slowing down the injection speed according to the present invention.

[0024] Description of main component markings

[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; elastic piece 91; first protrusion 92; rib position 93; spring holder 10; spring guide rod structure 1011; hook 1012; return spring 11. The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific embodiments Example 1:

[0026] Such as Figures 1-3As shown, an automatic injection pen capable of slowing down the injection speed includes a housing 4. The housing 4 is arranged along a longitudinal axis and has a proximal end and a distal end. A chamber for accommodating a syringe is provided inside the housing 4. The syringe includes a syringe body 3 and a piston 32 provided inside the syringe body 3. An injection mechanism 5 is provided in the chamber at the distal end of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved on the bottom of the syringe body 3, and a driving mechanism 7 for driving the axial movement of the injection push rod 6. The injection push rod 6 maintains a preset distance L from the piston 32 at the initial position. When the triggering mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to make it accelerate and accumulate kinetic energy. The injection push rod 6 breaks through its static friction resistance when contacting the piston 32 by virtue of this kinetic energy. During 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, so that the entire injection time is lengthened. The automatic injection pen is provided with a stepped resistance system, and its stepped resistance system has: a driving mechanism 7 starting resistance threshold F1, a piston 32 starting resistance threshold F2, and a piston 32 stable injection resistance threshold F3, where F1 < F3 < F2 is satisfied; the automatic injection pen is also provided with a dynamic energy management system, which includes: a pre-travel acceleration section, an energy release section, and a continuous control section. The pre-travel acceleration section is that 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 that at the moment when the injection push rod 6 contacts the piston 32, the kinetic energy makes the system instantaneously output a force greater than F2. The continuous control section is that 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-travel acceleration section is reduced to be greater than the sum of F1 and F2, and all driving mechanisms 7 in the energy release section and the continuous control section are greater than F3, resulting in a shorter injection time.

[0027] The distance between the injection push rod 6 and the piston 32 is 3 - 30 mm. An overly long distance will increase the length of the injection pen, and due to the long distance, there will be a sense of impact during injection. An overly short distance will result in a shorter 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 at the moment when the injection push rod 6 contacts the piston 32 is greater than F2. 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, 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 accelerated for a period of time before contacting the piston 32 and has obtained a 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 injection pain. The elastic driving module is an injection spring. Since the driving force value of the spring is a linear relationship, it can reduce the maximum compression force value. A smaller change rate is beneficial to stable injection, facilitating better control of the driving force in the pre-travel acceleration section and the driving force in the continuous control section. If the maximum compression force value is very large at the beginning, it will be very difficult to reduce the force value during the injection process and have a relatively small change rate.

[0028] Such as Figures 4-7As shown, the syringe body 3 is sleeved with the needle protection sleeve 2. A needle is installed at the front end of the syringe body 3, 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 selectively axially displace relative to the housing 4 along the longitudinal axis. An injection mechanism 5 is provided at the end of the needle protection sleeve 2 away from the proximal end. The injection push rod 6 has an axial accommodation channel, and its inner wall forms a continuous guiding structure; the elastic driving die is coaxially nested within the guiding structure, and its compression deformation direction coincides with the movement axis of the injection push rod 6; through the constraint cooperation between the guiding structure and the inner wall of the push rod, the elastic driving die is pre-compressed and energy is stored 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. A spring frame 10 penetrates through the injection spring. The spring frame 10 includes a spring guide rod structure 1011 provided in the middle of the spring frame 10 and spring arms provided on both sides of the spring frame 10. Hooks 1012 are provided at the top ends of the spring arms. The spring guide rod structure 1011 passes through the inside 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 guiding sleeve 8 is sleeved outside the spring frame 10. A platform structure 81 is provided at the upper part of the guiding sleeve 8. Before the injection pen is used, the platform structure 81 is engaged with the hook 1012. A guiding groove 82 is also provided at the guiding sleeve 8, and a wing-shaped structure 61 corresponding to the guiding groove 82 is provided at the injection push rod 6. A trigger sleeve 9 is sleeved outside the guiding sleeve 8. The upper end of the trigger sleeve 9 abuts against the needle protection sleeve 2. A spring piece 91 is provided at 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 at the trigger sleeve 9 corresponding to the wing-shaped structure 61. A return spring 11 is sleeved outside the trigger sleeve 9. During the use of the injection pen, the needle protection sleeve 2 pushes the trigger sleeve 9 downward. The spring piece 91 opens under the interaction between 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 within the guiding groove 82. The injection spring pushes the injection push rod 6 for injection. At the same time, the spring frame 10 moves downward, and the injection is completed.

[0029] Advantages of the present invention: The present invention provides an automatic injection pen capable of slowing down the injection speed, which includes a housing 4. The housing 4 is arranged along a longitudinal axis and has a proximal end and a distal end. A chamber for accommodating a syringe is provided inside the housing 4. The syringe includes a syringe body 3 and a piston 32 disposed inside the syringe body 3. An injection mechanism 5 is provided in the chamber at the distal end of the housing 4. The injection mechanism 5 includes an injection push rod 6 sleeved on the bottom of the syringe body 3, and a driving mechanism 7 for driving the axial movement of the injection push rod 6. The injection push rod 6 maintains a preset distance L from the piston 32 at the initial position. When the triggering mechanism is activated, the driving mechanism 7 applies a driving force to the injection push rod 6 to make it accelerate and accumulate kinetic energy. The injection push rod 6 breaks through its static friction resistance when contacting the piston 32 by virtue of this kinetic energy. During 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 lengthening the entire injection time.

[0030] The above embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. An automatic injection pen capable of slowing down injection speed, comprising a housing, the housing being arranged along a longitudinal axis and having a proximal end and a distal end, the housing being provided with a chamber for accommodating a syringe, the syringe comprising a syringe body and a piston arranged in the syringe body, an injection mechanism being provided in the distal end accommodating chamber of the housing, the injection mechanism comprising 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, characterized in that: The initial position of the injection push rod maintains a preset distance L with the piston. When the trigger mechanism is activated, the drive mechanism applies a driving force to the injection push rod to accelerate its movement and accumulate kinetic energy. The injection push rod breaks through the static friction resistance of the piston when it contacts the piston 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.

2. The automatic injection pen capable of slowing down the injection speed according to claim 1, characterized in that: The automatic injection pen is provided with a stepped resistance system, and the stepped resistance system has: a driving mechanism starting resistance threshold F1, a piston starting resistance threshold F2, and a piston smooth injection resistance threshold F3, wherein F1 < F3 < F2 is satisfied; 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 breaks away from the driving mechanism constraint and accelerates to accumulate kinetic energy. The energy release section is when the injection push rod and the piston contact at the moment, and the kinetic energy makes the system instantaneous output force 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.

3. The automatic injection pen capable of slowing down the 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 the injection speed according to claim 1, characterized in that: 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.

5. The automatic injection pen capable of slowing down the injection speed as claimed in claim 1, characterized in that: The elastic driving module is an injection spring.

6. The automatic injection pen capable of slowing down the injection speed as claimed in claim 4, 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 piston starting resistance, 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 piston starting resistance, and the driving force of the driving mechanism is auxiliary.

7. The automatic injection pen capable of slowing down the injection speed according to claim 6, characterized in that: The injection push rod has an axial accommodating channel, and its inner wall forms a continuous guiding structure; the elastic driving mold is coaxially nested in the guiding structure, and its compression deformation direction coincides with the movement axis of the injection push rod; through the constraint cooperation between the guiding structure and the inner wall of the push rod, the elastic driving mold is pre-compressed and stored in the push rod 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.

8. The automatic injection pen capable of slowing down the injection speed as claimed in claim 5, characterized in that: The injection spring is penetrated by a spring frame, and the spring frame 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, and a hook is arranged at the top of the elastic arm, and 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 arranged 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 also arranged at the guide sleeve, and a wing-shaped structure corresponding to the guide groove is arranged at the injection push rod. A trigger sleeve is arranged on the outer sleeve of the guide sleeve, and the upper end of the trigger sleeve abuts against the needle protection sleeve. A spring sheet is arranged at the trigger sleeve corresponding to the platform structure, and the inner wall of the spring sheet is provided with a first protrusion and abuts against the hook. The trigger sleeve is provided with a rib position corresponding to the wing-shaped structure, and the trigger sleeve outer sleeve is provided with a return spring. 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 and causes the trigger sleeve to move downward. 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 inject, and at the same time the spring frame moves downward, and the injection ends.

9. The automatic injection pen capable of slowing down the injection speed as claimed in 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 a mounting seat protruding from the syringe body is provided at the rear end, the mounting seat abuts against the inner wall of the needle protection sleeve, the needle protection sleeve can be selectively axially displaced relative to the shell along the longitudinal axis, and an injection mechanism is provided on the needle protection sleeve away from the proximal end.

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