A quantitative injection device and an emergency injection pen including it

Abstract

This utility model relates to the field of medical device manufacturing technology, and in particular to a quantitative injection mechanism and an emergency injection pen including the same. The quantitative injection mechanism includes an activation rod, an inner body, and a PFS assembly. The activation rod is provided with an upper radial extension limiting structure and a lower radial extension limiting structure. The inner body is sleeved around the activation rod, and a radial rebound blocking structure is formed on it. The PFS assembly includes a syringe barrel, a piston, and an injection needle. In the initial state, the upper extension limiting structure and the radial rebound blocking structure are interlocked, restricting the axial displacement freedom of the activation rod, and the piston is in the initial position inside the syringe barrel; when the emergency injection pen is triggered, the upper extension limiting structure and the radial rebound blocking structure are unlocked due to disengagement, and the activation rod moves downward under the action of driving force to push the piston; as the piston slides, the liquid is sprayed out through the injection needle until the lower radial extension limiting structure contacts the syringe barrel.

Description

Technical Field

[0001] This utility model relates to the field of medical device manufacturing technology, and in particular to a quantitative injection mechanism and an emergency injection pen including the same. Background Technology

[0002] In the field of medical injection, precise control of drug dosage is directly related to treatment efficacy and patient safety, especially in emergency situations, where dosage deviation can seriously affect the success rate of treatment. Traditional emergency injection pens mainly rely on manual injection by the operator. Due to the lack of a precise quantitative mechanism, dosage control is significantly affected by factors such as the force and speed of human operation, making it difficult to guarantee a constant dosage for a single injection.

[0003] Pre-filled syringes (PFS) simplify the usage process and reduce the risk of contamination by pre-filling medication, but they still have technical shortcomings in terms of quantitative injection functionality. Currently, most PFS-based quantitative emergency injection pens on the market use mechanical linkage structures for dosage control. However, such structures require extremely high precision in manufacturing processes. Even minor machining deviations or assembly errors in components can be amplified during use, leading to malfunctions in the linkage mechanism and consequently affecting dosage control accuracy. This results in a deviation between the actual injection dose after triggering and the preset value, failing to meet the stringent requirements of dosage accuracy and consistency in clinical treatment. Therefore, developing a new quantitative injection mechanism that overcomes these shortcomings and ensures a constant injection dose per action has become an urgent technical problem to be solved. Utility Model Content

[0004] This utility model discloses a quantitative injection mechanism, which aims to solve the problems of inaccurate dosage control and complex structure of existing emergency injection pens, and achieves high-precision quantitative injection by optimizing the mechanical structure.

[0005] This utility model relates to a quantitative injection mechanism, which includes an excitation rod, an inner body, and a PFS component.

[0006] An upper radial extension limiting structure and a lower radial extension limiting structure are provided at intervals along the axial direction of the excitation rod.

[0007] The inner body is fitted around the excitation rod, and a radial rebound blocking structure for locking the upper radial extension limiting structure is formed near its top.

[0008] The PFS component includes a syringe barrel, a piston, and an injection needle;

[0009] In the initial state, the axial displacement freedom of the upper extension limiting structure is restricted by the blocking force from the radial rebound blocking structure, and the piston is in the initial position inside the syringe barrel.

[0010] When the emergency injection pen is triggered, the upper outer limiting structure separates from the radial rebound blocking structure, and the trigger rod moves downward under the driving force to push the piston to compress the liquid medicine in the syringe. As the piston slides, the liquid medicine is sprayed out through the injection needle until the lower radial outer limiting structure contacts the syringe barrel, completing the quantitative injection.

[0011] As a further improvement to the technical solution disclosed in this utility model, the lower radially extending limiting structure includes M arc-shaped limiting bodies. The arc-shaped limiting bodies extend radially from the circumferential outer wall of the excitation rod. When M≥2, the multiple arc-shaped limiting bodies are evenly distributed circumferentially around the central axis of the excitation rod. The tail end of the syringe barrel has an annular stop flange that abuts against the arc-shaped limiting bodies.

[0012] As a further improvement to the technical solution disclosed in this utility model, the arc-shaped limiting body and the excitation rod are integrally formed. The perpendicularity tolerance between the annular stop flange and the axis of the syringe barrel does not exceed 0.05mm.

[0013] As a further improvement to the technical solution disclosed in this utility model, the inner cavity of the inner body is formed with a guide groove that is adapted to the arc-shaped limiting body, and the fit tolerance between the arc-shaped limiting body and the guide groove is controlled within ±0.03mm.

[0014] As a further improvement to the technical solution disclosed in this utility model, the axial distance between the lower radial extension limiting structure and the lower radial extension limiting structure is L1, and the axial distance from the initial position of the piston to the bottom of the syringe barrel is L2, which satisfies the relationship: L1=(0.95-1.05)L2.

[0015] As a further improvement to the technical solution disclosed in this utility model, the radially extending limiting structure includes N built-in limiting protrusions. The built-in limiting protrusions extend radially from the circumferential outer wall of the excitation rod. The radially rebound blocking structure includes N radially rebound arms. The radially rebound arms are formed by cutting and removing material from the circumferential outer wall of the inner body, and adjacent to their free ends, external limiting protrusions are formed to match the built-in limiting protrusions; and N≥1.

[0016] Furthermore, this utility model also discloses an emergency injection pen, which includes the aforementioned quantitative injection mechanism.

[0017] The quantitative injection mechanism disclosed in this utility model works in the following three stages:

[0018] Initial locking phase: The upper radially extended limiting structure and the radially rebound blocking structure form a mechanical interlock, restricting the axial movement of the trigger rod through a blocking force. At this time, the piston is in the initial position inside the syringe barrel, the liquid is sealed in the barrel, and the entire mechanism is in a ready-to-trigger state;

[0019] Triggering Phase: When the emergency injection pen is triggered, the radial rebound blocking structure undergoes elastic deformation (e.g., opens outward), thus disengaging from the upper radial extension limiting structure. At this time, the trigger rod begins to move axially downward under the action of a pre-stored driving force (e.g., the elastic force released by a compression spring);

[0020] Injection phase: During the downward movement of the excitation rod, its lower end contacts the piston and applies axial thrust, pushing the piston to slide downward along the inner wall of the syringe. During this process, the pressure of the liquid in the syringe increases due to volume compression, and the liquid is ejected through the injection needle. When the lower radial extension limiting structure comes into contact with the syringe barrel, the downward movement of the excitation rod is terminated, the piston stops sliding, and the quantitative injection is completed.

[0021] In practical applications, the quantitative injection mechanism disclosed in this utility model can achieve at least the following beneficial technical effects, specifically:

[0022] 1) The upper and lower radially extending limiting structures, spaced apart, work in conjunction with the inner body and syringe barrel to form a precise injection stroke control mechanism. The upper radially extending limiting structure is locked by the radial rebound blocking structure to ensure the stability of the initial state; when triggered, the excitation rod moves downward, and when the lower radially extending limiting structure comes into contact with the syringe barrel, the excitation rod stops moving, thus precisely limiting the axial movement distance of the excitation rod. The displacement of the piston is directly related to the downward movement distance of the excitation rod, thereby precisely controlling the movement stroke of the piston in the syringe barrel, ensuring that the volume of drug discharged each time is consistent, and achieving precise quantification.

[0023] 2) The inner body is fitted around the excitation rod, and the radial rebound blocking structure near its top and the upper radial extension limiting structure are closely matched. In the initial state, the axial displacement of the excitation rod is completely restricted, so as to avoid the excitation rod moving down prematurely due to accidental force and prevent the drug liquid from being discharged prematurely, causing dosage deviation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional schematic diagram of the emergency injection pen disclosed in this utility model.

[0026] Figure 2 yes Figure 1 Side view.

[0027] Figure 3 yes Figure 2 AA sectional view.

[0028] Figure 4 This is a schematic diagram of the quantitative injection mechanism disclosed in this utility model (i.e.) Figure 3 (A magnified view of part of I).

[0029] Figure 5 This is a three-dimensional schematic diagram of the excitation rod in the quantitative injection mechanism disclosed in this utility model.

[0030] Figure 6 This is a three-dimensional schematic diagram of the inner body of the quantitative injection mechanism disclosed in this utility model.

[0031] Figure 7 yes Figure 6 Side view.

[0032] Figure 8 yes Figure 7 CC section view.

[0033] Figure 9 yes Figure 7 DD sectional view.

[0034] Figure 10 yes Figure 4 A magnified view of part II.

[0035] Figure 11 yes Figure 4 BB cross-sectional view.

[0036] 1-Actuation rod; 11-Upper radial extension limiting structure; 111-Built-in limiting protrusion; 12-Lower radial extension limiting structure; 121-Arc-shaped limiting body; 2-Inner body; 21-Radial rebound blocking structure; 211-Radial rebound arm; 2111-External limiting protrusion; 22-Guide groove; 3-Outer body; 4-PFS assembly; 41-Injector syringe barrel; 411-Annular stop flange; 42-Piston; 43-Injection needle. Detailed Implementation

[0037] In the description of this utility model, it should be understood that the terms "left", "right", "front", "rear", "upper", "lower", etc., indicate the position or positional relationship based on the position or positional relationship shown in the drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, or be constructed and operated in a specific position, and therefore should not be construed as a limitation of this utility model.

[0038] An emergency injection pen is a portable automated injection device designed specifically for emergency medical scenarios. It is used to quickly and accurately administer emergency medications (such as adrenaline and insulin) to patients. Its core function is to complete puncture and medication delivery within a short time. The quantitative injection mechanism, as the core component of the emergency injection pen, directly affects the accuracy, reliability, and safety of medication injection in emergency situations.

[0039] The quantitative injection mechanism disclosed in this utility model will be further described in detail below with reference to specific embodiments, such as... Figures 1-4 As shown, the quantitative injection mechanism mainly consists of several parts, including the excitation rod 1, the inner body 2, the outer body 3, and the PFS component 4.

[0040] like Figure 5 As shown, the excitation rod 1 is simultaneously formed with an upper radially extending limiting structure 11 and a lower radially extending limiting structure 12, which are spaced apart along their axial direction by a set distance. The upper radially extending limiting structure 11 consists of two axially symmetrical built-in limiting protrusions 111. The lower radially extending limiting structure 12 consists of two axially symmetrical arc-shaped limiting bodies 121. Both the built-in limiting protrusions 111 and the arc-shaped limiting bodies 121 are formed by radially extending from the circumferential outer wall of the excitation rod 1.

[0041] like Figures 6-8 As shown, a radial spring-loaded blocking structure 21 is formed near its top end at a predetermined distance. The radial spring-loaded blocking structure 21 consists of two axially symmetrical radial spring-loaded arms 211. The radial spring-loaded arms 211 are formed by cutting and removing material from the circumferential outer wall of the inner body 2, and near its free end, an external limiting protrusion 2111 is formed to match the aforementioned built-in limiting protrusion 111.

[0042] like Figure 3 As shown, the PFS assembly 4 includes a syringe barrel 41, a piston 42, and an injection needle 43. The tail of the syringe barrel 41 has an annular stop flange 411 that abuts against the arc-shaped limiting body 121.

[0043] Initial locking phase: The radial rebound arm 211 is restricted by the binding force applied by the outer body 3 and cannot freely tilt outward. The upper radial extension limiting structure 11 (built-in limiting protrusion 111) and the radial rebound blocking structure 21 (external limiting protrusion 2111) interlock, restricting the axial movement of the excitation rod 1 (e.g., Figure 10 (as shown in the diagram); the piston 42 is in the initial position of the syringe barrel 41, and the medicine is pre-filled in the syringe barrel 41;

[0044] Triggering Phase: When the emergency injection pen is triggered, the circumferential restraint force applied to the radial rebound arm 211 is released; after the restraint force disappears, the radial rebound arm 211 tilts and expands outward on its own due to the radial component force applied by the built-in limiting protrusion 111. The external limiting protrusion 2111 disengages from the built-in limiting protrusion 111, and the axial movement restriction of the trigger rod 1 is released; the trigger rod 1 moves rapidly downward along the axial direction due to the axial thrust, and at the same time, the arc-shaped limiting body 121 used to limit the final stroke moves synchronously in response;

[0045] Injection stage: During the downward movement of the trigger rod 1, the piston 42 is pushed to compress the liquid medicine in the syringe; as the piston 42 continues to slide, the liquid medicine is sprayed out through the injection needle 43 until the arc-shaped limit body 121 abuts against the annular stop edge 411, thus completing the quantitative injection.

[0046] By adopting the above technical solution, on the one hand, the spaced-integrated built-in limiting protrusions 111 and arc-shaped limiting bodies 121 work together with the inner body 2, the outer body 3, and the syringe barrel 41 to form a precise injection stroke control mechanism. The built-in limiting protrusions 111 are locked by the external limiting protrusions 2111 to ensure the stability of the initial state; after being triggered, the excitation rod 1 moves downward, and when the arc-shaped limiting body 121 abuts against the annular stop edge 411, the excitation rod 1 stops moving, thus precisely limiting the axial movement distance of the excitation rod 1. The displacement of the piston 42 is directly related to the downward movement distance of the excitation rod 1, thereby precisely controlling the movement stroke of the piston 42 in the syringe barrel 41, ensuring that the volume of drug discharged each time is consistent, and achieving precise quantification; on the other hand, the excitation rod 1, the inner body 2, and the outer body 3 are sequentially assembled in a direction from the inside to the outside. The built-in limiting protrusion 111 near the top of the excitation rod 1 is mechanically interlocked with the external limiting protrusion 2111 near the top of the inner body 2. In the initial state, the axial displacement freedom of the excitation rod 1 is completely restricted, so as to avoid the excitation rod 1 moving down prematurely due to accidental force and prevent the drug liquid from being discharged prematurely, causing dosage deviation.

[0047] like Figure 5 As shown, the excitation rod 1 preferably adopts an integral injection molding process, and the built-in limiting protrusion 111 and the arc-shaped limiting body 121 are formed synchronously in the same injection molding process, which helps to ensure the positional accuracy and structural integrity of both.

[0048] As described above, the quantitative injection mechanism limits the stroke of the piston 42 by the contact between the arc-shaped limiting body 121 and the annular stop flange 411, thereby controlling the injection dosage. If the perpendicularity of the annular stop flange 411 is insufficient, the actuator rod 1 will inevitably tilt when it moves downward, resulting in a deviation in the stroke of the piston 42 and causing the actual injection dosage to deviate from the preset value. Therefore, as a further optimization of the above technical solution, the perpendicularity tolerance between the annular stop flange 411 and the syringe barrel 41 is no more than 0.05 mm. This ensures that the piston 42 moves precisely and consistently each time the actuator rod 1 moves downward to the limiting position, ensuring a constant volume of injected medication and achieving high-precision quantitative injection.

[0049] like Figures 6-9 As shown, a guide groove 22 is formed in the inner cavity of the inner body 2 to fit with the arc-shaped limiting body 121. In actual design, it is recommended that the fit tolerance between the arc-shaped limiting body 121 and the guide groove 22 be controlled within ±0.03mm. In this way, on the one hand, the guide groove 22 fits tightly with the arc-shaped limiting body 121, playing a precise guiding role during the downward movement of the excitation rod 1, limiting the radial offset of the excitation rod 1, ensuring its linear axial movement, and thus stabilizing the sliding path of the piston 42 in the syringe barrel 41; on the other hand, the wobbling amplitude of the excitation rod 1 during movement is significantly reduced, effectively avoiding the problem of abnormal fluctuations in drug pressure caused by the wobbling of the excitation rod 1, ensuring that the drug is output at a stable flow rate during injection, thereby further improving the accuracy and safety of quantitative injection.

[0050] Finally, it should be noted that, as Figure 3 As shown, the axial distance between the built-in limiting protrusion 111 and the arc-shaped limiting body 121 is L1, and the axial distance from the initial position of the piston 42 to the bottom of the syringe barrel 41 is L2. The stroke of the trigger rod 1 is determined by L1, while L2 directly affects the volume of drug discharged. Therefore, by limiting the ratio between L1 and L2, for example, L1 and L2 satisfy the relationship: L1 = (0.95-1.05)L2. In this way, not only can the complete discharge of drug be ensured, improving drug utilization, but also the piston 42 can be guaranteed to push the preset volume of drug when the trigger rod 1 completes its downward stroke. This ensures that the error in the volume of drug injected each time can be controlled within a very small range, and the accuracy of drug dosage is achieved.

[0051] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A metered dose injection mechanism characterized by, It includes an excitation rod, an inner body, and a PFS assembly; An upper radial extension limiting structure and a lower radial extension limiting structure are provided at intervals along the axial direction of the excitation rod; The inner body is sleeved around the excitation rod, and a radial rebound blocking structure for locking the upper radial extension limiting structure is formed near its top. The PFS component includes a syringe barrel, a piston, and an injection needle; In the initial state, the axial displacement freedom of the upper extended limiting structure is restricted by the blocking force from the radial rebound blocking structure, and the piston is in the initial position inside the syringe barrel. When the emergency injection pen is triggered, the upper extended limiting structure disengages from the radial rebound blocking structure, and the trigger rod moves downward under the driving force to push the piston to compress the liquid medicine in the syringe. As the piston slides, the liquid medicine is sprayed out through the injection needle until the lower radial extended limiting structure comes into contact with the syringe barrel.

2. The metered dose injection mechanism of claim 1, wherein, The lower radially extended limiting structure includes M arc-shaped limiting bodies; the arc-shaped limiting bodies are formed by radially extending from the circumferential outer wall of the excitation rod; and when M≥2, the multiple arc-shaped limiting bodies are evenly distributed circumferentially around the central axis of the excitation rod; the tail of the syringe barrel is formed with an annular stop edge that abuts against the arc-shaped limiting bodies.

3. The metered dose injection mechanism of claim 2, wherein, The arc-shaped limiting body and the excitation rod are integrally formed; the perpendicularity tolerance between the annular stop edge and the axis of the syringe barrel does not exceed 0.05mm.

4. The metered dose injection mechanism of claim 2, wherein, The inner cavity of the inner body is formed with a guide groove that is adapted to the arc-shaped limiting body, and the fit tolerance between the arc-shaped limiting body and the guide groove is controlled within ±0.03mm.

5. The metered dose injection mechanism of claim 1, wherein, The axial distance between the lower radial extension limiting structure and the lower radial extension limiting structure is L1, and the axial distance from the initial position of the piston to the bottom of the syringe barrel is L2, which satisfies the relationship: L1=(0.95-1.05)L2.

6. The metered dose injection mechanism of any of claims 1-5, wherein, The radially extended limiting structure includes N built-in limiting protrusions; the built-in limiting protrusions are formed by radially extending from the circumferential outer wall of the excitation rod; the radially rebound blocking structure includes N radially rebound arms; the radially rebound arms are formed by cutting and removing material from the circumferential outer wall of the inner body, and an external limiting protrusion adapted to the built-in limiting protrusions is formed near its free end; and N≥1.

7. An auto-injection pen, characterized in that Includes the quantitative injection device as described in any one of claims 1-6.

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